title: Cosmological Recombination

abstract:
  In this thesis we focus on studying the physics of cosmological recombination
and how the details of recombination affect the Cosmic Microwave Background
(CMB) anisotropies. We present a detailed calculation of the spectral line
distortions on the CMB spectrum arising from the Lyman-alpha and the lowest
two-photon transitions in the recombination of hydrogen (H), and the
corresponding lines from helium (He). The peak of these distortions mainly
comes from the Lyman-alpha transition and occurs at about 170 microns, which is
the Wien part of the CMB. The major theoretical limitation for extracting
cosmological parameters from the CMB sky lies in the precision with which we
can calculate the cosmological recombination process. With this motivation, we
perform a multi-level calculation of the recombination of H and He with the
addition of the spin-forbidden transition for neutral helium (He I), plus the
higher order two-photon transitions for H and among singlet states of He I. We
find that the inclusion of the spin-forbidden transition results in more than a
percent change in the ionization fraction, while the other transitions give
much smaller effects. Last we modify RECFAST by introducing one more parameter
to reproduce recent numerical results for the speed-up of helium recombination.
Together with the existing hydrogen `fudge factor', we vary these two
parameters to account for the remaining dominant uncertainties in cosmological
recombination. By using a Markov Chain Monte Carlo method with Planck forecast
data, we find that we need to determine the parameters to better than 10% for
He I and 1% for H, in order to obtain negligible effects on the cosmological
parameters.


title:
Evolutionary Construction of Geographical Networks with Nearly Optimal
  Robustness and Efficient Routing Properties

abstract:
  Robust and efficient design of networks on a realistic geographical space is
one of the important issues for the realization of dependable communication
systems. In this paper, based on a percolation theory and a geometric graph
property, we investigate such a design from the following viewpoints: 1)
network evolution according to a spatially heterogeneous population, 2)
trimodal low degrees for the tolerant connectivity against both failures and
attacks, and 3) decentralized routing within short paths. Furthermore, we point
out the weakened tolerance by geographical constraints on local cycles, and
propose a practical strategy by adding a small fraction of shortcut links
between randomly chosen nodes in order to improve the robustness to a similar
level to that of the optimal bimodal networks with a larger degree
$O(\sqrt{N})$ for the network size $N$. These properties will be useful for
constructing future ad-hoc networks in wide-area communications.

categories: physics.data-an cs.CG cs.NI physics.soc-ph


title: Transport and dynamical properties of inertial ratchets

abstract:
  In this paper we discuss the dynamics and transport properties of a massive
particle, in a time dependent periodic potential of the ratchet type, with a
dissipative environment. The directional currents and characteristics of the
motion are studied as the specific frictional coefficient varies, finding that
the stationary regime is strongly dependent on this parameter. The maximal
Lyapunov exponent and the current show large fluctuations and inversions,
therefore for some range of the control parameter, this inertial ratchet could
originate a mass separation device. Also an exploration of the effect of a
random force on the system is performed.


title: Hamiltonian Stationary Lagrangian Tori in Kaehler Manifolds

abstract:
  A Hamiltonian stationary Lagrangian submanifold of a Kaehler manifold is a
Lagrangian submanifold whose volume is stationary under Hamiltonian variations.
We find a sufficient condition on the curvature of a Kaehler manifold of real
dimension four that guarantees the existence of a family of small Hamiltonian
stationary Lagrangian tori.


title: Stationary Light Pulses in Cold Atomic Media

abstract:
  Stationary light pulses (SLPs), i.e., light pulses without motion, are formed
via the retrieval of stored probe pulses with two counter-propagating coupling
fields. We show that there exist non-negligible hybrid Raman excitations in
media of cold atoms that prohibit the SLP formation. We experimentally
demonstrate a method to suppress these Raman excitations and realize SLPs in
laser-cooled atoms. Our work opens the way to SLP studies in cold as well as in
stationary atoms and provides a new avenue to low-light-level nonlinear optics.


title:
Dynamics of Vesicle Formation from Lipid Droplet: Mechanism and
  Controllability

abstract:
  A coarse-grained model developed by Marrink et al. [J. Phys. Chem. B 111,
7812 (2007)] is applied to investigate vesiculation of lipid
[dipalmitoylphosphatidylcholine (DPPC)] droplets in water. Three kinds of
morphologies of micelles are found with increasing lipid droplet size. When the
initial lipid droplet is smaller, the equilibrium structure of the droplet is a
spherical micelle. When the initial lipid droplet is larger, the lipid ball
starts to transform into a disk micelle or vesicle. The mechanism of vesicle
formation from a lipid ball is analyzed from the self-assembly of DPPC on the
molecular level, and the morphological transition from disk to vesicle with
increasing droplet size is demonstrated. Importantly, we discover that the
transition point is not very sharp, and for a fixed-size lipid ball, the disk
and vesicle appear with certain probabilities. The splitting phenomenon, i.e.,
the formation of a disk/vesicle structure from a lipid droplet, is explained by
applying a hybrid model of the Helfrich membrane theory. The elastic module of
the DPPC bilayer and the smallest size of a lipid droplet for certain formation
of a vesicle are successfully predicted.


title: Geodesic Congruences in the Palatini f(R) Theory

abstract:
  We shall investigate the properties of a congruence of geodesics in the
framework of Palatini f(R) theories. We shall evaluate the modified geodesic
deviation equation and the Raychaudhuri's equation and show that f(R) Palatini
theories do not necessarily lead to attractive forces. Also we shall study
energy condition for f(R) Palatini gravity via a perturbative analysis of the
Raychaudhuri's equation.


title: A Rad-hard CMOS Active Pixel Sensor for Electron Microscopy

abstract:
  Monolithic CMOS pixel sensors offer unprecedented opportunities for fast
nano-imaging through direct electron detection in transmission electron
microscopy. We present the design and a full characterisation of a CMOS pixel
test structure able to withstand doses in excess of 1 MRad. Data collected with
electron beams at various energies of interest in electron microscopy are
compared to predictions of simulation and to 1.5 GeV electron data to
disentagle the effect of multiple scattering. The point spread function
measured with 300 keV electrons is (8.1 +/- 1.6) micron for 10 micron pixel and
(10.9 +/- 2.3) micron for 20 micron pixels, respectively, which agrees well
with the values of 8.4 micron and 10.5 micron predicted by our simulation.


title: Quantifying evolvability in small biological networks

abstract:
  We introduce a quantitative measure of the capacity of a small biological
network to evolve. We apply our measure to a stochastic description of the
experimental setup of Guet et al. (Science 296:1466, 2002), treating chemical
inducers as functional inputs to biochemical networks and the expression of a
reporter gene as the functional output. We take an information-theoretic
approach, allowing the system to set parameters that optimize signal processing
ability, thus enumerating each network's highest-fidelity functions. We find
that all networks studied are highly evolvable by our measure, meaning that
change in function has little dependence on change in parameters. Moreover, we
find that each network's functions are connected by paths in the parameter
space along which information is not significantly lowered, meaning a network
may continuously change its functionality without losing it along the way. This
property further underscores the evolvability of the networks.


title: Strong sums of projections in von Neumann factors

abstract:
  This paper presents necessary and sufficient conditions for a positive
bounded operator on a separable Hilbert space to be the sum of a finite or
infinite collection of projections (not necessarily mutually orthogonal), with
the sum converging in the strong operator topology if the collection is
infinite. A similar necessary condition is given when the operator and the
projections are taken in a type II von Neumann factor, and the condition is
proven to be also sufficient if the operator is "diagonalizable". A simpler
necessary and sufficient condition is given in the type III factor case.


title: Large thermomagnetic effects in weakly disordered Heisenberg chains

abstract:
  The interplay of different scattering mechanisms can lead to novel effects in
transport. We show theoretically that the interplay of weak impurity and
Umklapp scattering in spin-1/2 chains leads to a pronounced dip in the magnetic
field dependence of the thermal conductivity $\kappa$ at a magnetic field $B
\sim T$. In sufficiently clean samples, the reduction of the magnetic
contribution to heat transport can easily become larger than 50% and the effect
is predicted to exist even in samples with a large exchange coupling, J >> B,
where the field-induced magnetization is small. Qualitatively, our theory might
explain dips at $B \sim T$ observed in recent heat transport measurements on
copper pyrazine dinitrate, but a fully quantitative description is not possible
within our model.


title: Charge transport-mediated recruitment of DNA repair enzymes

abstract:
  Damaged or mismatched bases in DNA can be repaired by Base Excision Repair
(BER) enzymes that replace the defective base. Although the detailed molecular
structures of many BER enzymes are known, how they colocalize to lesions
remains unclear. One hypothesis involves charge transport (CT) along DNA
[Yavin, {\it et al.}, PNAS, {\bf 102}, 3546, (2005)]. In this CT mechanism,
electrons are released by recently adsorbed BER enzymes and travel along the
DNA. The electrons can scatter (by heterogeneities along the DNA) back to the
enzyme, destabilizing and knocking it off the DNA, or, they can be absorbed by
nearby lesions and guanine radicals. We develop a stochastic model to describe
the electron dynamics, and compute probabilities of electron capture by guanine
radicals and repair enzymes. We also calculate first passage times of electron
return, and ensemble-average these results over guanine radical distributions.
Our statistical results provide the rules that enable us to perform
implicit-electron Monte-Carlo simulations of repair enzyme binding and
redistribution near lesions. When lesions are electron absorbing, we show that
the CT mechanism suppresses wasteful buildup of enzymes along intact portions
of the DNA, maximizing enzyme concentration near lesions.


title: Mechanisms of receptor/coreceptor-mediated entry of enveloped viruses

abstract:
  Enveloped viruses enter host cells either through endocytosis, or by direct
fusion of the viral membrane envelope and the membrane of the host cell.
However, some viruses, such as HIV-1, HSV-1, and Epstein-Barr can enter a cell
through either mechanism, with the choice of pathway often a function of the
ambient physical chemical conditions, such as temperature and pH. We develop a
stochastic model that describes the entry process at the level of binding of
viral glycoprotein spikes to cell membrane receptors and coreceptors. In our
model, receptors attach the cell membrane to the viral membrane, while
subsequent binding of coreceptors enables fusion. The model quantifies the
competition between fusion and endocytotic entry pathways. Relative
probabilities for each pathway are computed numerically, as well as
analytically in the high viral spike density limit. We delineate parameter
regimes in which fusion or endocytosis is dominant. These parameters are
related to measurable and potentially controllable quantities such as membrane
bending rigidity and receptor, coreceptor, and viral spike densities.
Experimental implications of our mechanistic hypotheses are proposed and
discussed.


title: Maximal CP Violation Hypothesis and a Lepton Mixing Matrix

abstract:
  Maximal CP violation hypothesis is applied to a simple lepton mixing matrix
form U=V_{CKM}^\dagger U_{TB}, which has recently been speculated under an
ansatz that U becomes an exact tribimaximal mixing U_{TB} in a limit of the
quark mixing matrix V_{CKM} \to {\bf 1}. The prediction \tan^2 \theta_{12} =1/2
in the case of the exact tribimaximal mixing U=U_{TB} is onsiderably spoiled in
the speculated mixing U=V_{CKM}^\dagger U_{TB}. However, the application of the
hypothesis to the lepton sector can again recover the spoiled value to \tan^2
\theta_{12} \simeq 1/2 if the original Kobayashi-Maskawa phase convention for
V_{CKM} is adopted.


title:
Stellar Velocity Profiles and Line-Strengths out to Four Effective Radii
  in the Early-Type Galaxy NGC 3379

abstract:
  We describe a new technique to measure stellar kinematics and line-strengths
at large radii in nearby galaxies. Using the integral-field spectrograph SAURON
as a 'photon-collector', we obtain spectra out to four effective radii (Re) in
the early-type galaxy NGC 3379. By fitting orbit-based models to the extracted
stellar velocity profile, we find that ~40% of the total mass within 5 Re is
dark. The measured absorption line-strengths reveal a radial gradient with
constant slope out to 4 Re.


title: Universally Utility-Maximizing Privacy Mechanisms

abstract:
  A mechanism for releasing information about a statistical database with
sensitive data must resolve a trade-off between utility and privacy. Privacy
can be rigorously quantified using the framework of {\em differential privacy},
which requires that a mechanism's output distribution is nearly the same
whether or not a given database row is included or excluded. The goal of this
paper is strong and general utility guarantees, subject to differential
privacy.
  We pursue mechanisms that guarantee near-optimal utility to every potential
user, independent of its side information (modeled as a prior distribution over
query results) and preferences (modeled via a loss function).
  Our main result is: for each fixed count query and differential privacy
level, there is a {\em geometric mechanism} $M^*$ -- a discrete variant of the
simple and well-studied Laplace mechanism -- that is {\em simultaneously
expected loss-minimizing} for every possible user, subject to the differential
privacy constraint. This is an extremely strong utility guarantee: {\em every}
potential user $u$, no matter what its side information and preferences,
derives as much utility from $M^*$ as from interacting with a differentially
private mechanism $M_u$ that is optimally tailored to $u$.


title: Where are all the Young Stars in Aquila?

abstract:
  The high Galactic longitude end of the Aquila Rift comprises the large Aquila
molecular cloud complex, however, few young stars are known to be located in
the area, and only one is directly associated with the Rift. In contrast, the
Serpens star-forming region at the low Galactic longitude end of the Rift
contains hundreds of young stars. We review studies of the raw molecular
material and describe searches for young objects in the Aquila clouds. The
characteristics of the known young stars and associated jets and outflows are
also provided. Finally, we suggest some possible explanations for the dearth of
star formation in this gas-rich region and propose some future observations to
examine this mystery further.


title:
An Algorithm for Unconstrained Quadratically Penalized Convex
  Optimization

abstract:
  A descent algorithm, "Quasi-Quadratic Minimization with Memory" (QQMM), is
proposed for unconstrained minimization of the sum, $F$, of a non-negative
convex function, $V$, and a quadratic form. Such problems come up in
regularized estimation in machine learning and statistics. In addition to
values of $F$, QQMM requires the (sub)gradient of $V$. Two features of QQMM
help keep low the number of evaluations of the objective function it needs.
First, QQMM provides good control over stopping the iterative search. This
feature makes QQMM well adapted to statistical problems because in such
problems the objective function is based on random data and therefore stopping
early is sensible. Secondly, QQMM uses a complex method for determining trial
minimizers of $F$. After a description of the problem and algorithm a
simulation study comparing QQMM to the popular BFGS optimization algorithm is
described. The simulation study and other experiments suggest that QQMM is
generally substantially faster than BFGS in the problem domain for which it was
designed. A QQMM-BFGS hybrid is also generally substantially faster than BFGS
but does better than QQMM when QQMM is very slow.


title: Consistency of Random Survival Forests

abstract:
  We prove uniform consistency of Random Survival Forests (RSF), a newly
introduced forest ensemble learner for analysis of right-censored survival
data. Consistency is proven under general splitting rules, bootstrapping, and
random selection of variables--that is, under true implementation of the
methodology. A key assumption made is that all variables are factors. Although
this assumes that the feature space has finite cardinality, in practice the
space can be a extremely large--indeed, current computational procedures do not
properly deal with this setting. An indirect consequence of this work is the
introduction of new computational methodology for dealing with factors with
unlimited number of labels.


title:
Magnetic order, Bose-Einstein condensation, and superfluidity in a
  bosonic t-J model of CP^1 spinons and doped Higgs holons

abstract:
  We study the three-dimensional U(1) lattice gauge theory of a CP$^1$ spinon
(Schwinger boson) field and a Higgs field. It is a bosonic $t$-$J$ model in
slave-particle representation, describing the antiferromagnetic (AF) Heisenberg
spin model with doped bosonic holes expressed by the Higgs field. The spinon
coupling term of the action favors AF long-range order, whereas the holon
hopping term in the ferromagnetic channel favors Bose-Einstein condensation
(BEC) of holons. We investigate the phase structure by means of Monte-Carlo
simulations and study an interplay of AF order and BEC of holes. We consider
the two variations of the model; (i) the three-dimensional model at finite
temperatures, and (ii) the two-dimensional model at vanishing temperature. In
the model (i) we find that the AF order and BEC coexist at low temperatures and
certain hole concentrations. In the model (ii), by varying the hole
concentration and the stiffness of AF spin coupling, we find a phase diagram
similar to the model (i). Implications of the results to systems of cold atoms
and the fermionic $t$-$J$ model of strongly-correlated electrons are discussed.


title: Perturbations of Spacetime around a Stationary Rotating Cosmic String

abstract:
  We consider the metric perturbations around a stationary rotating Nambu-Goto
string in Minkowski spacetime. By solving the linearized Einstein equations, we
study the effects of azimuthal frame-dragging around the rotation axis and
linear frame-dragging along the rotation axis, the Newtonian logarithmic
potential, and the angular deficit around the string as the potential mode. We
also investigate gravitational waves propagating off the string and propagating
along the string, and show that the stationary rotating string emits
gravitational waves toward the directions specified by discrete angles from the
rotation axis. Waveforms, polarizations, and amplitudes which depend on the
direction are shown explicitly.


title:
Boosting the Accuracy of Finite Difference Schemes via Optimal Time Step
  Selection and Non-Iterative Defect Correction

abstract:
  In this article, we present a simple technique for boosting the order of
accuracy of finite difference schemes for time dependent partial differential
equations by optimally selecting the time step used to advance the numerical
solution and adding defect correction terms in a non-iterative manner. The
power of the technique is its ability to extract as much accuracy as possible
from existing finite difference schemes with minimal additional effort. Through
straightforward numerical analysis arguments, we explain the origin of the
boost in accuracy and estimate the computational cost of the resulting
numerical method. We demonstrate the utility of optimal time step (OTS)
selection combined with non-iterative defect correction (NIDC) on several
different types of finite difference schemes for a wide array of classical
linear and semilinear PDEs in one and more space dimensions on both regular and
irregular domains.


title:
Fast decay of the velocity autocorrelation function in dense shear flow
  of inelastic hard spheres

abstract:
  We find in complementary experiments and event driven simulations of sheared
inelastic hard spheres that the velocity autocorrelation function $\psi(t)$
decays much faster than $t^{-3/2}$ obtained for a fluid of elastic spheres at
equilibrium. Particle displacements are measured in experiments inside a
gravity driven flow sheared by a rough wall. The average packing fraction
obtained in the experiments is 0.59, and the packing fraction in the
simulations is varied between 0.5 and 0.59. The motion is observed to be
diffusive over long times except in experiments where there is layering of
particles parallel to boundaries, and diffusion is inhibited between layers.
Regardless, a rapid decay of $\psi(t)$ is observed, indicating that this is a
feature of the sheared dissipative fluid, and is independent of the details of
the relative particle arrangements. An important implication of our study is
that the non-analytic contribution to the shear stress may not be present in a
sheared inelastic fluid, leading to a wider range of applicability of kinetic
theory approaches to dense granular matter.


title: Analysis of spectral methods for the homogeneous Boltzmann equation

abstract:
  The development of accurate and fast algorithms for the Boltzmann collision
integral and their analysis represent a challenging problem in scientific
computing and numerical analysis. Recently, several works were devoted to the
derivation of spectrally accurate schemes for the Boltzmann equation, but very
few of them were concerned with the stability analysis of the method. In
particular there was no result of stability except when the method is modified
in order to enforce the posivity preservation, which destroys the spectral
accuracy. In this paper we propose a new method to study the stability of
homogeneous Boltzmann equations perturbed by smoothed balanced operators which
do not preserve positivity of the distribution. This method takes advantage of
the "spreading" property of the collision, together with estimates on
regularity and entropy production. As an application we prove stability and
convergence of spectral methods for the Boltzmann equation, when the
discretization parameter is large enough (with explicit bound).


title: Codes against Online Adversaries

abstract:
  In this work we consider the communication of information in the presence of
an online adversarial jammer. In the setting under study, a sender wishes to
communicate a message to a receiver by transmitting a codeword x=x_1,...,x_n
symbol-by-symbol over a communication channel. The adversarial jammer can view
the transmitted symbols x_i one at a time, and can change up to a p-fraction of
them. However, the decisions of the jammer must be made in an online or causal
manner. More generally, for a delay parameter 0<d<1, we study the scenario in
which the jammer's decision on the corruption of x_i must depend solely on x_j
for j < i - dn. In this work, we initiate the study of codes for online
adversaries, and present a tight characterization of the amount of information
one can transmit in both the 0-delay and, more generally, the d-delay online
setting. We prove tight results for both additive and overwrite jammers when
the transmitted symbols are assumed to be over a sufficiently large field F.
Finally, we extend our results to a jam-or-listen online model, where the
online adversary can either jam a symbol or eavesdrop on it. We again provide a
tight characterization of the achievable rate for several variants of this
model. The rate-regions we prove for each model are informational-theoretic in
nature and hold for computationally unbounded adversaries. The rate regions are
characterized by "simple" piecewise linear functions of p and d. The codes we
construct to attain the optimal rate for each scenario are computationally
efficient.


title:
Some physics of the two-dimensional $\mathcal{N}=(2,2)$ supersymmetric
  Yang-Mills theory: Lattice Monte Carlo study

abstract:
  We illustrate some physical application of a lattice formulation of the
two-dimensional $\mathcal{N}=(2,2)$ supersymmetric SU(2) Yang-Mills theory with
a (small) supersymmetry breaking scalar mass. Two aspects, power-like behavior
of certain correlation functions (which implies the absence of the mass gap)
and the static potential $V(R)$ between probe charges in the fundamental
representation, are considered. For the latter, for $R\lesssim1/g$, we observe
a linear confining potential with a finite string tension. This confining
behavior appears distinct from a theoretical conjecture that a probe charge in
the fundamental representation is screened in two-dimensional gauge theory with
an adjoint massless fermion, although the static potential for $R\gtrsim1/g$
has to be systematically explored to conclude real asymptotic behavior in large
distance.


title:
Extended GWS Model Using Left-Right Symmetry and Its Prediction on
  Neutrino Mass

abstract:
  We evaluate the predictions of the left-right symmetry model based on
$SU(2)\otimes U(1)$ gauge group with one bidoublet and one doublet Higgs fields
on the parity violation, charged leptons and neutrinos masses. Parity violation
in the weak interaction is due to the very large $M_{W_{R}}$ mass compare to
the $M_{W_{L}}$ mass. The charged leptons acquire a Dirac mass via ordinary
Higgs mechanism, meanwhile the neutrinos acquire a very small Dirac masses via
seesaw-like mechanism with values $m_{1}=0.000043$ eV, $m_{2}=0.008888$ eV,
$m_{3}=0.014948$ eV when $\rho=8.4\times 10^{-11}$, or m_{1}=0.000014$ eV,
$m_{2}=0.003032$ eV, $m_{3}=0.050990$ eV when $\rho=2.9\times 10^{-11}$.


title: Generating Random Networks Without Short Cycles

abstract:
  Random graph generation is an important tool for studying large complex
networks. Despite abundance of random graph models, constructing models with
application-driven constraints is poorly understood. In order to advance
state-of-the-art in this area, we focus on random graphs without short cycles
as a stylized family of graphs, and propose the RandGraph algorithm for
randomly generating them. For any constant k, when m=O(n^{1+1/[2k(k+3)]}),
RandGraph generates an asymptotically uniform random graph with n vertices, m
edges, and no cycle of length at most k using O(n^2m) operations. We also
characterize the approximation error for finite values of n. To the best of our
knowledge, this is the first polynomial-time algorithm for the problem.
RandGraph works by sequentially adding $m$ edges to an empty graph with n
vertices. Recently, such sequential algorithms have been successful for random
sampling problems. Our main contributions to this line of research includes
introducing a new approach for sequentially approximating edge-specific
probabilities at each step of the algorithm, and providing a new method for
analyzing such algorithms.


title:
Lp estimates for non smooth bilinear Littlewood-Paley square functions
  on R

abstract:
  In this work, some non smooth bilinear analogues of linear Littlewood-Paley
square functions on the real line are studied. These bilinear operators are
closely related to the bilinear Hilbert transforms and vector valued version of
these ones. Mainly we prove boundedness-properties in Lebesgue spaces for them.


title: Superconformal Indices for Orbifold Chern-Simons Theories

abstract:
  We calculate the superconformal indices of recently discovered
three-dimensional N=4,5 Chern-Simons-matter theories and compare them with the
corresponding indices of supergravity on AdS4 times orbifolds of S7. We find
perfect agreement in the large N and large k limit, provided that the twisted
sector contributions at the fixed loci of the orbifolds are properly taken into
account. We also discuss the index for the so-called "dual ABJM" proposal.


title: On the exact treatment of Time Dependent Self-Interaction Correction

abstract:
  We present a new formulation of the time-dependent self-interaction
correction (TDSIC). It is derived variationally obeying explicitly the
constraints on orthonormality of the occupied single-particle orbitals. The
thus emerging rather involved symmetry condition amongst the orbitals is dealt
with using two separate sets of (occupied) single-particle wavefunctions,
related by a unitary transformation. The double-set TDSIC scheme is well suited
for numerical implementation. We present results for laser-excited dynamics in
a 1D model for a molecule and in fully fledged 3D calculations.


title: Noise induced interference fringes in trapped ultracold bosonic gases

abstract:
  We study the dynamics of ultracold atoms trapped in optical double-well
potentials in presence of noise generated by an external environment. When
prepared in a Fock number state, the system shows phase coherence in the
averaged density profile obtained using standard absorption image techniques,
that disappears in absence of noise. This effect indicates that also in
many-body systems an external environment may enhance quantum coherence,
instead of destroying it.


title:
Molecular dynamics simulations of complex shaped particles using
  Minkowski operators

abstract:
  The Minkowski operators (addition and substraction of sets in vectorial
spaces) has been extensively used for Computer Graphics and Image Processing to
represent complex shapes. Here we propose to apply those mathematical concepts
to extend the Molecular Dynamics (MD) Methods for simulations with
complex-shaped particles. A new concept of Voronoi-Minkowski diagrams is
introduced to generate random packings of complex-shaped particles with tunable
particle roundness. By extending the classical concept of Verlet list we
achieve numerical efficiencies that do not grow quadratically with the body
number of sides. Simulations of dissipative granular materials under shear
demonstrate that the method complies with the first law of thermodynamics for
energy balance.


title: Exploring the consequences of pairing algorithms for binary stars

abstract:
  Knowledge of the binary population in stellar groupings provides important
information about the outcome of the star forming process in different
environments (see, e.g., Blaauw 1991, and references therein). Binarity is also
a key ingredient in stellar population studies, and is a prerequisite to
calibrate the binary evolution channels. In this paper we present an overview
of several commonly used methods to pair individual stars into binary systems,
which we refer to as pairing functions. These pairing functions are frequently
used by observers and computational astronomers, either for their mathematical
convenience, or because they roughly describe the expected outcome of the star
forming process. We discuss the consequences of each pairing function for the
interpretation of observations and numerical simulations. The binary fraction
and mass ratio distribution generally depend strongly on the selection of the
range in primary spectral type in a sample. The mass ratio distribution and
binary fraction derived from a binarity survey among a mass-limited sample of
targets is thus not representative for the population as a whole. Neither
theory nor observations indicate that random pairing of binary components from
the mass distribution, the simplest pairing function, is realistic. It is more
likely that companion stars are formed in a disk around a star, or that a
pre-binary core fragments into two binary components. The results of our
analysis are important for (i) the interpretation of the observed mass ratio
distribution and binary fraction for a sample of stars, (ii) a range of
possible initial condition algorithms for star cluster simulations, and (iii)
how to discriminate between the different star formation scenarios.


title: Tropical rational equivalence on R^r

abstract:
  We introduce an improved version of rational equivalence in tropical
intersection theory which can be seen as a replacement of chapter 8 of our
previous article arXiv:0709.3705v2. Using this new definition, rational
equivalence is compatible with push-forwards of cycles. Moreover, we prove that
every tropical cycle in R^r is equivalent to a uniquely determined affine
cycle, called its degree.


title:
Universal Critical Velocity for the Onset of Turbulence of Oscillatory
  Superfluid Flow

abstract:
  The critical velocity vc for the onset of turbulent drag of small spheres
oscillating in superfluid 4He is frequency dependent (omega/2pi from 100 Hz to
700 Hz) and is described by vc = 2.6sqrt(kappa*omega), where kappa is the
circulation quantum. A qualitative analysis based on a recent theory of the
onset of superfluid turbulence gives vc = sqrt(8*kappa*omega/beta), where beta
is of order 1 and depends on the coefficients of mutual friction. This agrees
well with the data and implies that vc is a universal critical velocity that is
independent of geometry, size, and surface properties of the oscillating body.
This is confirmed by comparing our data on spheres with vc obtained with other
oscillating structures by other groups. Numerical simulations indicate somewhat
larger critical velocity, above which a rapid increase in vortex length is
observed.


title: Non-local Realistic Theories and the Scope of the Bell Theorem

abstract:
  According to a widespread view, the Bell theorem establishes the untenability
of so-called 'local realism'. On the basis of this view, recent proposals by
Leggett, Zeilinger and others have been developed according to which it can be
proved that even some non-local realistic theories have to be ruled out. As a
consequence, within this view the Bell theorem allows one to establish that no
reasonable form of realism, be it local or non-local, can be made compatible
with the (experimentally tested) predictions of quantum mechanics. In the
present paper it is argued that the Bell theorem has demonstrably nothing to do
with the 'realism' as defined by these authors and that, as a consequence,
their conclusions about the foundational significance of the Bell theorem are
unjustified.


title:
Three-dimensional numerical simulations of the pulsar magentoshere:
  Preliminary results

abstract:
  We investigate the three-dimensional structure of the pulsar magnetosphere
through time-dependent numerical simulations of a magnetic dipole that is set
in rotation. We developed our own Eulerian finite difference time domain
numerical solver of force-free electrodynamics and implemented the technique of
non-reflecting and absorbing outer boundaries. This allows us to run our
simulations for many stellar rotations, and thus claim with confidence that we
have reached a steady state. A quasi-stationary corotating pattern is
established, in agreement with previous numerical solutions. We discuss the
prospects of our code for future high-resolution investigations of dissipation,
particle acceleration, and temporal variability.


title:
An in-depth view of the microscopic dynamics of Ising spin glasses at
  fixed temperature

abstract:
  Using the dedicated computer Janus, we follow the nonequilibrium dynamics of
the Ising spin glass in three dimensions for eleven orders of magnitude. The
use of integral estimators for the coherence and correlation lengths allows us
to study dynamic heterogeneities and the presence of a replicon mode and to
obtain safe bounds on the Edwards-Anderson order parameter below the critical
temperature. We obtain good agreement with experimental determinations of the
temperature-dependent decay exponents for the thermoremanent magnetization.
This magnitude is observed to scale with the much harder to measure coherence
length, a potentially useful result for experimentalists. The exponents for
energy relaxation display a linear dependence on temperature and reasonable
extrapolations to the critical point. We conclude examining the time growth of
the coherence length, with a comparison of critical and activated dynamics.


title:
Three-dimensional simulations of ion dynamics in the plasma of an
  Electron Cyclotron Resonance Ion Source

abstract:
  The ion production in an ECRIS is modelled using a particle-in-cell
Monte-Carlo collision code in a three-dimensional geometry. Only the heavy
particles (ions and atoms) are tracked, with the electron density determined
from the requirement of quasi-neutrality, and the electron temperature is a
free parameter. The electric fields in the plasma are assumed to be negligibly
small, and the ion confinement due to a "potential dip" is neglected. It is
found that experimentally observed features of ECRIS plasma are closely
reproduced by the code, including the charge-state-distributions of extracted
ion beams and sputtering patterns inside the source. The isotope anomaly is
observed for the mixture of 20Ne + 22Ne isotopes, and some explanation for the
effect is given. Possible connection between the wall-coating effect and
parameters of the fast atoms created in collisions of the ions with the walls
is discussed.


title:
Very simple FET amplifier with a voltage noise floor less than 1
  nV/sqrt(Hz)

abstract:
  A field-effect transistor (FET) amplifier for small voltage signals is
presented. Its design is elementary and the construction can be afforded by
anyone. Despite its simplicity, with a voltage noise less than 1 nV/sqrt(Hz),
it outperforms commercially available integrated FET amplifiers. The amplifier
has a gain flatness better than 1 dB over 1 MHz bandwidth; it can be employed
as a front-end for signal analyzers or signal recovery systems.


title:
Performance of the Imaging Fourier Transform Spectrometer with
  Photoconductive Detector Arrays: An Application for the AKARI Far-Infrared
  Instrument

abstract:
  We have developed an imaging Fourier transform spectrometer (FTS) for
space-based far-infrared astronomical observations. The FTS employs a newly
developed photoconductive detector arrays with a capacitive trans-impedance
amplifier, which makes the FTS a completely unique instrument. The FTS was
installed as a function of the far-infrared instrument (FIS: Far-Infrared
Surveyor) on the Japanese astronomical satellite, AKARI, which was launched on
February 21, 2006 (UT) from the Uchinoura Space Center. The FIS-FTS had been
operated for more than one year before liquid helium ran out on August 26,
2007. The FIS-FTS was operated nearly six hundreds times, which corresponds to
more than one hundred hours of astronomical observations and almost the same
amount of time for calibrations. As expected from laboratory measurements, the
FIS-FTS performed well and has produced a large set of astronomical data for
valuable objects. Meanwhile, it becomes clear that the detector transient
effect is a considerable factor for FTSs with photoconductive detectors. In
this paper, the instrumentation of the FIS-FTS and interesting phenomena
related to FTS using photoconductive detectors are described, and future
applications of this kind of FTS system are discussed.


title: Approximate Sparse Decomposition Based on Smoothed L0-Norm

abstract:
  In this paper, we propose a method to address the problem of source
estimation for Sparse Component Analysis (SCA) in the presence of additive
noise. Our method is a generalization of a recently proposed method (SL0),
which has the advantage of directly minimizing the L0-norm instead of L1-norm,
while being very fast. SL0 is based on minimization of the smoothed L0-norm
subject to As=x. In order to better estimate the source vector for noisy
mixtures, we suggest then to remove the constraint As=x, by relaxing exact
equality to an approximation (we call our method Smoothed L0-norm Denoising or
SL0DN). The final result can then be obtained by minimization of a proper
linear combination of the smoothed L0-norm and a cost function for the
approximation. Experimental results emphasize on the significant enhancement of
the modified method in noisy cases.


title: Origin of Middle-Infrared Peaks in Cerium Compounds

abstract:
  We have demonstrated that the middle-infrared (mid-IR) peaks in the optical
conductivity spectra of Ce$X_3$ ($X$ = Pd, Sn, In) can be explained by
first-principle band structure calculation with the spin-orbit interaction. The
mid-IR peak shapes in these materials are not identical to one another:
CePd$_3$, CeSn$_3$, and CeIn$_3$ have a triple-peak structure, double-peak
structure and broad single-peak structure, respectively. These peaks can be
theoretically explained by the optical transition from the occupied state to
the spin-orbit splitted Ce $4f$ state. This result indicates that the mid-IR
peaks originate from the simple band picture with the Ce $4f$ state near the
Fermi level, not from the conventional cf hybridization gap based on the
periodic Anderson model.


title:
Completely monotonic functions of positive order and asymptotic
  expansions of the logarithm of Barnes double gamma function and Euler's gamma
  function

abstract:
  We introduce completely monotonic functions of order
  $r>0$ and show that the remainders in asymptotic expansions of the logarithm
of Barnes double gamma function and Euler's gamma function give rise to
completely monotonic functions of any positive integer order.


title:
Semilinear ordinary differential equation coupled with distributed order
  fractional differential equation

abstract:
  System of semilinear ordinary differential equation and fractional
differential equation of distributed order is investigated and solved in a mild
and classical sense. Such a system arises as a distributed derivative model of
viscoelasticity and in the system identfica- tion theory. Also, the existence
and uniqueness of a solution to a general linear fractional differential
equation in the space of tempered distributions is given.


title:
Experimental verification of broadband cloaking using a volumetric cloak
  composed of periodically stacked cylindrical transmission-line networks

abstract:
  Cloaking using a volumetric structure composed of stacked two-dimensional
transmission-line networks is verified with measurements. The measurements are
done in a waveguide, in which an array of metallic cylinders is inserted
causing a short-circuit in the waveguide. The metal cylinders are cloaked using
a previously designed and simulated cloak that hides the cylinders and thus
enables wave propagation inside the waveguide.


title: Type IIB Flux Vacua from M-theory via F-theory

abstract:
  We study in detail some aspects of duality between type IIB and M-theory. We
focus on the duality between type IIB string theory on K3 x T^2/Z_2 orientifold
and M-theory on K3 x K3, in the F-theory limit. We give the explicit map
between the fields and in particular between the moduli of compactification,
studying their behavior under the F-theory limit. Turning on fluxes generates a
potential for the moduli both in type IIB and in M-theory. We verify that the
type IIB analysis gives the same results of the F-theory analysis. In
particular, we check that the two potentials match.


title:
Relativistic, QED, and finite nuclear mass corrections for low-lying
  states of Li and Be$^+$

abstract:
  Accurate results for nonrelativistic energy, relativistic, QED, and finite
nuclear mass corrections are obtained for $2^1S_{1/2}$, $3^1S_{1/2}$ and
$2^1P_{1/2}$ states of the Li atom and Be$^+$ ion. Our computational approach
uses the Hylleraas basis set with the analytic integration and recursion
relations. From comparison of experimental results for the isotope shifts to
theoretical predictions including nuclear polarizabilities, we obtain nuclear
charge radii for Li and Be isotopes.


title:
A Forward semi-Lagrangian Method for the Numerical Solution of the
  Vlasov Equation

abstract:
  This work deals with the numerical solution of the Vlasov equation. This
equation gives a kinetic description of the evolution of a plasma, and is
coupled with Poisson's equation for the computation of the self-consistent
electric field. The coupled model is non linear. A new semi-Lagrangian method,
based on forward integration of the characteristics, is developed. The
distribution function is updated on an eulerian grid, and the pseudo-particles
located on the mesh's nodes follow the characteristics of the equation forward
for one time step, and are deposited on the 16 nearest nodes. This is an
explicit way of solving the Vlasov equation on a grid of the phase space, which
makes it easier to develop high order time schemes than the backward method.


title: Non-minimal curvature-matter couplings in modified gravity

abstract:
  Recently, in the context of f(R) modified theories of gravity, it was shown
that a curvature-matter coupling induces a non-vanishing covariant derivative
of the energy-momentum, implying non-geodesic motion and, under appropriate
conditions, leading to the appearance of an extra force. We study the
implications of this proposal and discuss some directions for future research.


title: Stationary Metrics and Optical Zermelo-Randers-Finsler Geometry

abstract:
  We consider a triality between the Zermelo navigation problem, the geodesic
flow on a Finslerian geometry of Randers type, and spacetimes in one dimension
higher admitting a timelike conformal Killing vector field. From the latter
viewpoint, the data of the Zermelo problem are encoded in a (conformally)
Painleve-Gullstrand form of the spacetime metric, whereas the data of the
Randers problem are encoded in a stationary generalisation of the usual optical
metric. We discuss how the spacetime viewpoint gives a simple and physical
perspective on various issues, including how Finsler geometries with constant
flag curvature always map to conformally flat spacetimes and that the Finsler
condition maps to either a causality condition or it breaks down at an
ergo-surface in the spacetime picture. The gauge equivalence in this network of
relations is considered as well as the connection to analogue models and the
viewpoint of magnetic flows. We provide a variety of examples.


title: N-body simulations in modified Newtonian dynamics

abstract:
  We describe some results obtained with N-MODY, a code for N-body simulations
of collisionless stellar systems in modified Newtonian dynamics (MOND). We
found that a few fundamental dynamical processes are profoundly different in
MOND and in Newtonian gravity with dark matter. In particular, violent
relaxation, phase mixing and galaxy merging take significantly longer in MOND
than in Newtonian gravity, while dynamical friction is more effective in a MOND
system than in an equivalent Newtonian system with dark matter.


title:
Confining string beyond the free approximation: the case of random
  percolation

abstract:
  The random percolation model can be viewed as the dual of a well defined
confining gauge theory; since this theory, having no Monte Carlo dynamics at
all, is simple to simulate, it is possible to study the properties of the flux
tube with very high precision; we show it can be described by the effective
string picture. Our results are lattice regularisation independent, therefore
they are well defined also in the continuum limit, and, for the first time in a
gauge theory, it has been possible to determine the next-to-leading quantum
corrections throughout the computation of the T^6 coefficient of the Taylor
expansion of sigma(T). Furthermore, this coefficient results to be related to
the universal ratio T_c/\sqrt{sigma_0}.


title:
Isospin Dynamics in Heavy Ion Collisions: from Coulomb Barrier to Quark
  Gluon Plasma

abstract:
  Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium
nuclear interaction in regions away from saturation. In this report we present
a selection of new reaction observables in dissipative collisions particularly
sensitive to the symmetry term of the nuclear Equation of State (Iso-EoS). We
will first discuss the Isospin Equilibration Dynamics. At low energies this
manifests via the recently observed Dynamical Dipole Radiation, due to a
collective neutron-proton oscillation with the symmetry term acting as a
restoring force. At higher beam energies Iso-EoS effects will be seen in
Imbalance Ratio Measurements, in particular from the correlations with the
total kinetic energy loss. For fragmentation reactions in central events we
suggest to look at the coupling between isospin distillation and radial flow.
In Neck Fragmentation reactions important $Iso-EoS$ information can be obtained
from the correlation between isospin content and alignement. The high density
symmetry term can be probed from isospin effects on heavy ion reactions at
relativistic energies (few AGeV range). Rather isospin sensitive observables
are proposed from nucleon/cluster emissions, collective flows and meson
production. The possibility to shed light on the controversial neutron/proton
effective mass splitting in asymmetric matter is also suggested. A large
symmetry repulsion at high baryon density will also lead to an "earlier"
hadron-deconfinement transition in n-rich matter. A suitable treatment of the
isovector interaction in the partonic EoS appears very relevant.


title: Spin Needlets for Cosmic Microwave Background Polarization Data Analysis

abstract:
  Scalar wavelets have been used extensively in the analysis of Cosmic
Microwave Background (CMB) temperature maps. Spin needlets are a new form of
(spin) wavelets which were introduced in the mathematical literature by Geller
and Marinucci (2008) as a tool for the analysis of spin random fields. Here we
adopt the spin needlet approach for the analysis of CMB polarization
measurements. The outcome of experiments measuring the polarization of the CMB
are maps of the Stokes Q and U parameters which are spin 2 quantities. Here we
discuss how to transform these spin 2 maps into spin 2 needlet coefficients and
outline briefly how these coefficients can be used in the analysis of CMB
polarization data. We review the most important properties of spin needlets,
such as localization in pixel and harmonic space and asymptotic uncorrelation.
We discuss several statistical applications, including the relation of angular
power spectra to the needlet coefficients, testing for non-Gaussianity on
polarization data, and reconstruction of the E and B scalar maps.


title:
Lightlike Brane as a Gravitational Source of Misner-Wheeler-Type
  Wormhole

abstract:
  Consistent Lagrangian description of lightlike p-branes (LL-branes) is
presented in two equivalent forms - a Polyakov-type formulation and a dual to
it Nambu-Goto-type formulation. An important characteristic feature of the
LL-branes is that the brane tension appears as a non-trivial additional
dynamical degree of freedom. Next, properties of p=2 LL-brane dynamics (as a
test brane) in D=4 Kerr or Kerr-Newman gravitational backgrounds are discussed
in some detail. It is shown that the LL-brane automatically positions itself on
the horizon and rotates along with the same angular velocity. Finally, a
Misner-Wheeler-type of Reissner-Nordstroem wormhole is constructed in a
self-consistent electrically sourceless Einstein-Maxwell system in the D=4 bulk
interacting with a LL-brane. The pertinent wormhole throat is located precisely
at the LL-brane sitting on the outer Reissner-Nordstroem horizon with the
Reissner-Nordstroem mass and charge being functions of the dynamical LL-brane
tension.


title:
Numerical simulation of the magnetization of high-temperature
  superconductors: 3D finite element method using a single time-step iteration

abstract:
  We make progress towards a 3D finite-element model for the magnetization of a
high temperature superconductor (HTS): We suggest a method that takes into
account demagnetisation effects and flux creep, while it neglects the effects
associated with currents that are not perpendicular to the local magnetic
induction. We consider samples that are subjected to a uniform magnetic field
varying linearly with time. Their magnetization is calculated by means of a
weak formulation in the magnetostatic approximation of the Maxwell equations
(A-phi formulation). An implicit method is used for the temporal resolution
(Backward Euler scheme) and is solved in the open source solver GetDP. Picard
iterations are used to deal with the power law conductivity of HTS. The finite
element formulation is validated for an HTS tube with large pinning strength
through the comparison with results obtained with other well-established
methods. We show that carrying the calculations with a single time-step (as
opposed to many small time-steps) produce results with excellent accuracy in a
drastically reduced simulation time. The numerical method is extended to the
study of the trapped magnetization of cylinders that are drilled with different
arrays of columnar holes arranged parallel to the cylinder axis.


title:
The LVD Core Facility: a study of LVD as muon veto and active shielding
  for dark matter experiments

abstract:
  In this study we explore the possibility of using the existing structure of a
running experiment, the LVD supernova observatory at the INFN Gran Sasso
National Laboratory, as an active shield and veto for the muon-induced
background. In our vision LVD could become (without affecting in any way its
main purpose of SN neutrino telescope) a host for a relatively compact but
massive experiment looking for rare events. The empty volume that can be
obtained removing 2 modules from the most internal part of the detector is 2.1m
x 6.2m x 2.8m; we will call it LVD Core Facility (LVD-CF). We have evaluated
the active vetoing and shielding power of LVD, with a detailed MC simulation
(based on Geant4) of the detector and the rock that surrounds it. The results
show that the flux of neutrons that are not associated with a visible muon in
LVD is very low; it results reduced by a factor 50, equivalent to the one
present in a much deeper underground laboratory, i.e. Sudbury. Moreover we
present the results of on-going measurements about the gamma contamination
inside the LVD-CF: it is reduced by a factor greater than 10 with respect to
the one measured outside the LVD detector.


title:
Bulk etch rate measurements and calibrations of CR39 and Makrofol
  nuclear track detectors

abstract:
  We developed a new method for determining the bulk etch rate velocity based
on both cone height and base diameter measurements of the etched tracks. This
method is applied here for the calibration of CR39 and Makrofol nuclear track
detectors exposed to 158 A GeV In^{49+} and Pb^{82+} ions, respectively. For
CR39 the peaks corresponding to indium ions and their different fragments are
well separated from Z/beta = 7 to 49: the detection threshold is at REL ~ 50
MeV cm^2 g^{-1}, corresponding to a nuclear fragment with Z/beta = 7. The
calibration of Makrofol with Pb^{82+} ions has shown all peaks due to lead ions
and their fragments from Z/beta ~ 51 to 83 (charge pickup). The detection
threshold of Makrofol is at REL ~ 2700 MeV cm^2 g^{-1}, corresponding to a
nuclear fragment with Z/beta = 51.


title:
Powering via Cooling Pipes: an Optimized Design for an SLHC Silicon
  Tracker

abstract:
  Silicon trackers at the SLHC will suffer high radiation damage from particles
produced during the collisions, which leads to high leakage currents. Reducing
these currents in the sensors requires efficient cooling to -30 C. The large
heat of evaporation of CO2 and the low viscosity allows for a two-phase cooling
system with thin and long cooling pipes, because the small flow of liquid
needed leads to negligible temperature drops. In order to reduce the material
budget a system is proposed in which a large scale tracker requiring ca. 50 kW
of power is powered via 1-2 mm diameter aluminum cooling pipes with a length of
several m. These long cooling pipes allow to have all service connections
outside the tracking volume, thus reducing the material budget significantly.
The whole system is designed to have negligible thermal stresses. A CO2 blow
system has been designed and first tests show the feasibility of a barrel
detector with long ladders and disks at small radii leading to an optimized
design with respect to material budget and simplicity in construction.


title:
Quantum Logical Gates with Linear Quadripartite Cluster States of
  Continuous Variables

abstract:
  The concrete schemes to realize three types of basic quantum logical gates
using linear quadripartite cluster states of optical continuous variables are
proposed. The influences of noises and finite squeezing on the computation
precision are analyzed in terms of the fidelity of propagated quantum
information through the continuous variable cluster states. The proposed
schemes provide direct references for the design of experimental systems of
one-way quantum computer based on the cluster entanglement of amplitude and
phase quadratures of light.


title: Composite fermions in Electroweak Symmetry Breaking

abstract:
  If the electroweak symmetry is broken by some unspecified strong dynamics,
composite fermions may exist with definite transformation properties under
SU(2)_L x SU(2)_R/SU(2)_{L+R} and may play a role in giving masses by mixing to
all the standard quarks and leptons. Assuming this to be the case, we analyze
the role of Singlets, Doublets and Triplets in the ElectroWeak Precision Tests
and in Flavour Physics. Doublets and Triplets are generically disfavoured. In
the Singlet case, we specify the breaking patterns of the flavour group that
allow to keep the CKM picture of flavour physics and we discuss the effects of
the mixing between composite and elementary fermions. These mixings affect in
particular the rather peculiar LHC phenomenology of the composite fermions.


title: Quaternions and dynamics

abstract:
  We give a simple and self contained introduction to quaternions and their
practical usage in dynamics. The rigid body dynamics are presented in full
details. In the appendix, some more exotic relations are given that allow to
write more complex models, for instance, the one of a satellite with inertial
wheels and expressed in a non-inertial reference frame. As it is well known,
one nice advantage of quaternions over Euler angles, beside the usual
arguments, is that it allows to write down quite complex dynamics completely by
hand.


title: On the Geometric Principles of Surface Growth

abstract:
  We introduce a new equation describing epitaxial growth processes. This
equation is derived from a simple variational geometric principle and it has a
straightforward interpretation in terms of continuum and microscopic physics.
It is also able to reproduce the critical behavior already observed, mound
formation and mass conservation, but however does not fit a divergence form as
the most commonly spread models of conserved surface growth. This formulation
allows us to connect the results of the dynamic renormalization group analysis
with intuitive geometric principles, whose generic character may well allow
them to describe surface growth and other phenomena in different areas of
physics.


title:
Precise limits from lepton flavour violating processes on the Littlest
  Higgs model with T-parity

abstract:
  We recalculate the leading one-loop contributions to mu > e gamma and mu ->
eee in the Littlest Higgs model with T-parity, recovering previous results for
the former. When all the Goldstone interactions are taken into account, the
latter is also ultraviolet finite. The present experimental limits on these
processes require a somewhat heavy effective scale ~2.5 TeV, or the flavour
alignment of the Yukawa couplings of light and heavy leptons at the ~10% level,
or the splitting of heavy lepton masses to a similar precision. Present limits
on tau decays set no bounds on the corresponding parameters involving the tau
lepton


title:
An Upper Bound on the critical density for Activated Random Walks on
  Euclidean Lattices

abstract:
  We show the critical density for activated random walks on Euclidean lattices
is at most one.


title: A Magnetohydrodynamic Model for the Formation of Episodic Jets

abstract:
  Episodic ejection of plasma blobs have been observed in many black hole
systems. While steady, continuous jets are believed to be associated with
large-scale open magnetic fields, what causes the episodic ejection of blobs
remains unclear. Here by analogy with the coronal mass ejection on the Sun, we
propose a magnetohydrodynamical model for episodic ejections from black holes
associated with the closed magnetic fields in an accretion flow. Shear and
turbulence of the accretion flow deform the field and result in the formation
of a flux rope in the disk corona. Energy and helicity are accumulated and
stored until a threshold is reached. The system then loses its equilibrium and
the flux rope is thrust outward by the magnetic compression force in a
catastrophic way. Our calculations show that for parameters appropriate for the
black hole in our Galactic center, the plasmoid can attain relativistic speeds
in about 35 minutes.


title: Current non-conservation effects in $\nu$DIS diffraction

abstract:
  In the neutrino DIS diffraction the charged current non-conservation gives
rise to sizable corrections to the longitudinal structure function, $F_L$.
These corrections is a higher twist effect enhanced at small-$x$ by the rapidly
growing gluon density. The phenomenon manifests itself in abundant production
of charm and strangeness by longitudinally polarized W bosons of moderate
virtualities $Q^2\lsim m_c^2$.


title: Subfields of ample fields I. Rational maps and definability

abstract:
  Pop proved that a smooth curve C over an ample field K that has a K-rational
point has |K| many K-rational points. We strengthen this result by showing that
there are |K| many K-rational points that do not lie in a given proper
subfield, even after applying a rational map. As a consequence we gain insight
into the structure of existentially definable subsets of ample fields. In
particular, we prove that a perfect ample field has no existentially definable
proper infinite subfields.


title:
Planets in Stellar Clusters Extensive Search. V. Search for planets and
  identification of 18 new variable stars in the old open cluster NGC 188

abstract:
  We have undertaken a long-term project, Planets in Stellar Clusters Extensive
Search (PISCES), to search for transiting planets in open clusters. In this
paper we present the results for NGC 188, an old, rather populous cluster. We
have monitored the cluster for more than 87 hours, spread over 45 nights. We
have not detected any good transiting planet candidates. We have discovered 18
new variable stars in the cluster, bringing the total number of identified
variables to 46, and present for them high precision light curves, spanning 15
months.


title: Very-High Energy Gamma-Ray Flux Limits for Nearby Active Galactic Nuclei

abstract:
  Combining the results of targeted observations, H.E.S.S. has accumulated a
large amount of extra-galactic exposure at TeV energies. Due to its large field
of view a considerable part of the sky (0.6 sr) has been observed with high
sensitivity outside the targeted observation positions. Since this exposure
region contains little inherent bias, it is well suited for studies of
extra-galactic source populations. Given the correlation between ultra-high
energy cosmic rays and nearby extra-galactic objects recently claimed by the
Auger collaboration, this unbiased sky sample by H.E.S.S. is of interest since
it includes (besides the targeted sources) 63 AGN within 100 Mpc, for which
very-high energy gamma-ray flux limits are derived.


title: Optical manipulation of a single Mn spin in a CdTe-based quantum dot

abstract:
  A system of two coupled CdTe quantum dots, one of them containing a single Mn
ion, was studied in continuous wave and modulated photoluminescence,
photoluminescence excitation, and photon correlation experiments. Optical
writing of information in the spin state of the Mn ion has been demonstrated,
using orientation of the Mn spin by spin-polarized carriers transferred from
the neighbor quantum dot. Mn spin orientation time values from 20 ns to 100 ns
were measured, depending on the excitation power. Storage time of the
information in the Mn spin was found to be enhanced by application of a static
magnetic field of 1 T, reaching hundreds of microseconds in the dark. Simple
rate equation models were found to describe correctly static and dynamical
properties of the system.


title: Automatic Classification of Restricted Lattice Walks

abstract:
  We propose an experimental mathematics approach leading to the
computer-driven discovery of various structural properties of general counting
functions coming from enumeration of walks.


title:
Flux algebra, Bianchi identities and Freed-Witten anomalies in F-theory
  compactifications

abstract:
  We discuss the structure of 4D gauged supergravity algebras corresponding to
globally non-geometric compactifications of F-theory, admitting a local
geometric description in terms of 10D supergravity. By starting with the well
known algebra of gauge generators associated to non-geometric type IIB fluxes,
we derive a full algebra containing all, closed RR and NSNS, geometric and
non-geometric dual fluxes. We achieve this generalization by a systematic
application of SL(2,Z) duality transformations and by taking care of the
spinorial structure of the fluxes. The resulting algebra encodes much
information about the higher dimensional theory. In particular, tadpole
equations and Bianchi identities are obtainable as Jacobi identities of the
algebra. When a sector of magnetized (p,q) 7-branes is included, certain closed
axions are gauged by the U(1) transformations on the branes. We indicate how
the diagonal gauge generators of the branes can be incorporated into the full
algebra, and show that Freed-Witten constraints and tadpole cancellation
conditions for (p,q) 7-branes can be described as Jacobi identities satisfied
by the algebra mixing bulk and brane gauge generators.


title: Dual parametrization of GPDs versus the double distribution Ansatz

abstract:
  We establish a link between the dual parametrization of GPDs and a popular
parametrization based on the double distribution Ansatz, which is in prevalent
use in phenomenological applications. We compute several first forward-like
functions that express the double distribution Ansatz for GPDs in the framework
of the dual parametrization and show that these forward-like functions make the
dominant contribution into the GPD quintessence function. We also argue that
the forward-like functions $Q_{2 \nu}(x)$ with $\nu \ge 1$ contribute to the
leading singular small-$x_{Bj}$ behavior of the imaginary part of DVCS
amplitude. This makes the small-$x_{Bj}$ behavior of $\im A^{DVCS}$ independent
of the asymptotic behavior of PDFs. Assuming analyticity of Mellin moments of
GPDs in the Mellin space we are able to fix the value of the $D$-form factor in
terms of the GPD quintessence function $N(x,t)$ and the forward-like function
$Q_0(x,t)$.


title: Interstellar Extinction and Long-Period Variables in the Galactic Center

abstract:
  We use the Spitzer IRAC catalogue of the Galactic Center (GC) point sources
(Ramirez et al. 2008) and combine it with new isochrones (Marigo et al. 2008)
to derive extinctions based on photometry of red giants and asymptotic giant
branch (AGB) stars. This new extinction map extends to much higher values of Av
than previoulsy available. Our new extinction map of the GC region covers 2.0 x
1.4 degree (280 x 200 pc at a distance of 8 kpc). We apply it to deredden the
LPVs found by Glass et al. (2001) near the GC. We make period-magnitude
diagrams and compare them to those from other regions of different metallicity.
  The Glass-LPVs follow well-defined period-luminosity relations (PL) in the
IRAC filter bands at 3.6, 4.5, 5.8, and 8.0 micron. The period-luminosity
relations are similar to those in the Large Magellanic Cloud, suggesting that
the PL relation in the IRAC bands is universal. We use ISOGAL data to derive
mass-loss rates and find for the Glass-LPV sample some correlation between
mass-loss and pulsation period, as expected theoretically.The GC has an excess
of high luminosity and long period LPVs compared to the Bulge, which supports
previous suggestions that it contains a younger stellar population.


title: Detection of Dense Molecular Gas in Inter-Arm Spurs in M51

abstract:
  Spiral arm spurs are prominent features that have been observed in extinction
and 8$\mu$m emission in nearby galaxies. In order to understand their molecular
gas properties, we used the Owens Valley Radio Observatory to map the
CO(J=1--0) emission in three spurs emanating from the inner northwestern spiral
arm of M51. We report CO detections from all three spurs. The molecular gas
mass and surface density are M$_{H2} \sim3\times10^6$ M$_{\sun}$ and
$\Sigma_{H2} \sim$50 M$_{\sun}$ pc$^{-2}$. Thus, relative to the spiral arms,
the spurs are extremely weak features. However, since the spurs are extended
perpendicular to the spiral arms for $\sim$500 pc and contain adequate fuel for
star formation, they may be the birthplace for observed inter-arm HII regions.
This reduces the requirement for the significant time delay that would be
otherwise needed if the inter-arm star formation was initiated in the spiral
arms. Larger maps of galaxies at similar depth are required to further
understand the formation and evolution of these spurs and their role in star
formation - such data should be forthcoming with the new CARMA and future ALMA
telescopes and can be compared to several recent numerical simulations that
have been examining the evolution of spiral arm spurs.


title: Secondary Indexing in One Dimension: Beyond B-trees and Bitmap Indexes

abstract:
  Let S be a finite, ordered alphabet, and let x = x_1 x_2 ... x_n be a string
over S. A "secondary index" for x answers alphabet range queries of the form:
Given a range [a_l,a_r] over S, return the set I_{[a_l;a_r]} = {i |x_i \in
[a_l; a_r]}. Secondary indexes are heavily used in relational databases and
scientific data analysis. It is well-known that the obvious solution, storing a
dictionary for the position set associated with each character, does not always
give optimal query time. In this paper we give the first theoretically optimal
data structure for the secondary indexing problem. In the I/O model, the amount
of data read when answering a query is within a constant factor of the minimum
space needed to represent I_{[a_l;a_r]}, assuming that the size of internal
memory is (|S| log n)^{delta} blocks, for some constant delta > 0. The space
usage of the data structure is O(n log |S|) bits in the worst case, and we
further show how to bound the size of the data structure in terms of the 0-th
order entropy of x. We show how to support updates achieving various time-space
trade-offs.
  We also consider an approximate version of the basic secondary indexing
problem where a query reports a superset of I_{[a_l;a_r]} containing each
element not in I_{[a_l;a_r]} with probability at most epsilon, where epsilon >
0 is the false positive probability. For this problem the amount of data that
needs to be read by the query algorithm is reduced to O(|I_{[a_l;a_r]}|
log(1/epsilon)) bits.


title:
Solution to Satisfiability problem by a complete Grover search with
  trapped ions

abstract:
  The main idea in the original Grover search (Phys. Rev. Lett. 79, 325 (1997))
is to single out a target state containing the solution to a search problem by
amplifying the amplitude of the state, following the Oracle's job, i.e., a
black box giving us information about the target state. We design quantum
circuits to accomplish a complete Grover search involving both the Oracle's job
and the amplification of the target state, which are employed to solve
Satisfiability (SAT) problems. We explore how to carry out the quantum circuits
by currently available ion-trap quantum computing technology.


title: Lithium abundances in exoplanet-host stars : modelling

abstract:
  Aims. Exoplanet-host stars (EHS) are known to present superficial chemical
abundances different from those of stars without any detected planet (NEHS).
EHS are, on the average, overmetallic compared to the Sun. The observations
also show that, for cool stars, lithium is more depleted in EHS than in NEHS.
The aim of this paper is to obtain constraints on possible models able to
explain this difference, in the framework of overmetallic models compared to
models with solar abundances. Methods. We have computed main sequence stellar
models with various masses and metallicities. The results show different
behaviour for the lithium destruction according to those parameters. We compare
these results to the spectroscopic observations of lithium. Results. Our models
show that the observed lithium differences between EHS and NEHS are not
directly due to the overmetallicity of the EHS: some extra mixing is needed
below the convective zones. We discuss possible explanations for the needed
extra mixing, in particular an increase of the mixing efficiency associated
with the development of shear instabilities below the convective zone,
triggered by angular momentum transfer due to the planetary migration.


title:
Quantitative complementarity between local and nonlocal character of
  quantum states in a three-qubit system

abstract:
  Local or nonlocal character of quantum states can be quantified and is
subject to various bounds that can be formulated as complementarity relations.
Here, we investigate the local vs. nonlocal character of pure three-qubit
states by a four-way interferometer. The complete entanglement in the system
can be measured as the entanglement of a specific qubit with the subsystem
consisting of the other two qubits. The quantitative complementarity relations
are verified experimentally in an NMR quantum information processor.


title: Stellar ages from asteroseismology

abstract:
  Asteroseismology provides powerful means to probe stellar interiors. The
oscillations frequencies are closely related to stellar interior properties via
the density and sound speed profiles. Since these are tightly linked with the
mass and evolutionary state, we can expect to determine the age and mass of a
star from the comparison of its oscillation spectrum with predictions of
stellar models. Such a comparison suffers both from the problems we face when
modeling a particular star (as the uncertainties on global parameters and
chemical composition) and from our misunderstanding of processes at work in
stellar interiors (as the transport processes that may lead to core mixing and
affect the model ages). For stars where observations have provided precise and
numerous oscillation frequencies together with accurate global parameters and
additional information (as the radius or the mass if the star is in a binary
system, the interferometric radius or the mean density if the star is an
exoplanet host), we can also expect to better constrain the physical
description of the stellar structure and to get a more reliable age estimation.
After a survey of stellar pulsations, we present some seismic diagnostics that
can be used to infer the age of a star as well as their limitations. We then
illustrate the ability of asteroseismology to scrutinize stellar interiors on
the basis of a few exemples. In the years to come, extended very precise
asteroseismic observations are expected, in photometry or in spectroscopy, from
ground-based (HARPS, CORALIE, ELODIE, UVES, UCLES, SIAMOIS, SONG) or spatial
devices (MOST, CoRoT, WIRE, Kepler, PLATO). This will considerably enlarge the
sample of stars eligible to asteroseismic age determination and should allow to
estimate the age of individual stars with a 10-20% accuracy.


title:
Generic Variables in Acyclic Cluster Algebras and Bases in Affine
  Cluster Algebras

abstract:
  Let $Q$ be a finite quiver without oriented cycles and $\mathcal A(Q)$ be the
coefficient-free cluster algebra with initial seed $(Q,\textbf u)$. Using the
Caldero-Chapoton map, we introduce and investigate a family of generic
variables in $\Z[\textbf u^{\pm 1}]$ containing the cluster monomials of
$\mathcal A(Q)$. The aim of these generic variables is to give an explicit new
method for constructing $\Z$-bases in the cluster algebra $\mathcal A(Q)$.
  If $Q$ is an affine quiver with minimal imaginary root $\delta$, we
investigate differences between cluster characters associated to indecomposable
representations of dimension vector $\delta$. We define the notion of
\emph{difference property} which gives an explicit description of these
differences. We prove in particular that this property holds for quivers of
affine type $\tilde A$. When $Q$ satisfies the difference property, we prove
that generic variables span the cluster algebra $\mathcal A(Q)$. If $\mathcal
A(Q)$ satisfies some gradability condition, we prove that generic variables are
linearly independent over $\mathbb Z$ in $\mathcal A(Q)$. In particular, this
implies that generic variables form a $\Z$-basis in a cluster algebra
associated to an affine quiver of type $\tilde A$.


title: Visualizing some ideas about Godel-type rotating universes

abstract:
  This paper consists mostly of pictures visualizing ideas leading to Godel's
rotating cosmological model. The pictures are constructed according to concrete
metric tensor fields. Information about these are in the last chapters. The
main aim is to visualise ideas.


title:
Long-lived Charginos in the Focus-point Region of the MSSM Parameter
  Space

abstract:
  We analyse the possibility to get light long-lived charginos within the
framework of the MSSM with gravity mediated SUSY breaking. We find out that
this possibility can be realized in the so-called focus-point region of
parameter space. The mass degeneracy of higgsino-like chargino and two
higgsino-like neutralinos is the necessary condition for a long lifetime. It
requires the fine-tuning of parameters, but being a single additional
constraint in the whole parameter space it can be fulfilled in the Constrained
MSSM along the border line where radiative electroweak symmetry breaking fails.
In a narrow band close to the border line the charginos are long-lived
particles. The cross-sections of their production and co-production at the LHC
via electroweak interaction reach a few tenth of pb.


title: Extending CKKW-merging to One-Loop Matrix Elements

abstract:
  We extend earlier schemes for merging tree-level matrix elements with parton
showers to include also merging with one-loop matrix elements. In this paper we
make a first study on how to include one-loop corrections, not only for events
with a given jet multiplicity, but simultaneously for several different jet
multiplicities. Results are presented for the simplest non-trivial case of
hadronic events at LEP as a proof-of-concept.


title:
Local magnetization fluctuations in superconducting glasses resolved by
  Hall sensors

abstract:
  We report on magnetization measurements performed on a series of
Fe$_{x}$Ni$_{1-x}$Zr$_{2}$ superconducting metallic glasses with $0\leq
x\leq0.5$ using the Hall effect of a nearby 2-dimensional electron gas (2DEG)
in a GaAs/Al$_{0.33}$Ga$_{0.67}$As heterostructure as a local probe. The great
sensitivity of the Hall effect of the 2DEG in such heterostructure is exploited
to determine the magnetization of the superconductor due to the Meissner effect
and flux trapping. The data is used to determine the lower critical field
B$_{c1}$ of the superconductors as a function of temperature. Surprisingly
large fluctuations in the magnetization are also observed and attributed to the
presence of large flux clusters in the superconductor.


title: Spin states of the first four holes in a silicon nanowire quantum dot

abstract:
  We report measurements on a silicon nanowire quantum dot with a clarity that
allows for a complete understanding of the spin states of the first four holes.
First, we show control of the hole number down to one. Detailed measurements at
perpendicular magnetic fields reveal the Zeeman splitting of a single hole in
silicon. We are able to determine the ground-state spin configuration for one
to four holes occupying the quantum dot and find a spin filling with
alternating spin-down and spin-up holes, which is confirmed by
magnetospectroscopy up to 9T. Additionally, a so far inexplicable feature in
single-charge quantum dots in many materials systems is analyzed in detail. We
observe excitations of the zero-hole ground-state energy of the quantum dot,
which cannot correspond to electronic or Zeeman states. We show that the most
likely explanation is acoustic phonon emission to a cavity between the two
contacts to the nanowire.


title: Parabolic foliations on 3-manifolds

abstract:
  In the paper we prove that every closed orientable three-manifold admits a
parabolic foliation.


title: Classification of Fuchsian systems and their connection problem

abstract:
  We review the Deligne-Simpson problem, a combinatorial structure of middle
convolutions and their relation to a Kac-Moody root system discoverd by
Crawley-Boevey. We show with examples that middle convolutions transform the
Fuchsian systems with a fixed number of accessory parameters into fundamental
systems whose spectral type is in a finite set and we give an explicit
connection formula for solutions of Fuchsian differential equations without
moduli.


title: On the second Tate-Shafarevich group of a 1-motive

abstract:
  We prove finiteness results for Tate--Shafarevich groups in degree 2
associated with 1--motives, rely them to Leopoldt's conjecture, and present an
example of a semiabelian variety with an infinite Tate--Shafarevich group in
degree 2. We also establish an arithmetic duality theorem for 1--motives over
number fields which complements earlier results of Harari and Szamuely in this
direction.


title: Depinning of three-dimensional drops from wettability defects

abstract:
  Substrate defects crucially influence the onset of sliding drop motion under
lateral driving. A finite force is necessary to overcome the pinning influence
even of microscale heterogeneities. The depinning dynamics of three-dimensional
drops is studied for hydrophilic and hydrophobic wettability defects using a
long-wave evolution equation for the film thickness profile. It is found that
the nature of the depinning transition explains the experimentally observed
stick-slip motion.


title: Unifying disc-jet behaviour in X-ray binaries: an optical/IR approach

abstract:
  Synchrotron emission from jets produced by X-ray binaries can be detected at
optical and infrared (IR) frequencies. I show that optical/IR colour-magnitude
diagrams of the outbursts of nine X-ray binaries successfully separate thermal
disc emission from non-thermal jet emission, in both black hole and neutron
star sources. A heated single-temperature blackbody is able to reproduce the
observed relations between colour and magnitude, except when excursions are
made to a redder colour than expected, which is due to jet emission. The
general picture that is developed is then incorporated into the unified picture
of disc-jet behaviour in black hole X-ray binaries. At a given position of a
source in the X-ray hardness-intensity diagram, the radio, IR and optical
properties can be inferred. Similarly, it is possible to predict the X-ray and
radio luminosities and spectral states from optical/IR monitoring.


title:
Abnormal T-linear susceptibility and Phase diagram of
  BaFe$_{2-x}$Co$_x$As$_2$ single crystals

abstract:
  We study systematically transport, susceptibility and heat capacity for
BaFe$_{2-x}$Co$_x$As$_2$ single crystals. In the underdoped region, spin
density wave (SDW) transition is observed in both resistivity and
susceptibility. The magnetic susceptibility shows unusual T-linear dependence
above SDW transition up to 700 K. With Co doping, SDW ordering is gradually
suppressed and superconductivity emerges with a dome-like shape. Electrical
transport, specific heat and magnetic susceptibility indicate that SDW and
superconductivity coexist in the sample BaFe$_{2-x}$Co$_x$As$_2$ around x =
0.17, being similar with (Ba,K)Fe$_2$As$_2$. When x$>$0.34, the
superconductivity completely disappears. A crossover from non-Fermi-liquid
state to Fermi-liquid state is observed with increasing Co doping. A detailed
electronic phase diagram about evolution from SDW to superconducting state is
given.


title: Prospects for studies of high-energy solar cosmic rays with ATLAS

abstract:
  The ATLAS detector is intended to verify the standard model and to search for
new physics at the Large Hadron Collider (LHC, CERN). In addition to this
primary goal, it also allows detection of muons of cosmic rays. On the other
hand, unusual bursts of the muon intensity, which correlate with powerful solar
flares were recorded and investigated earlier at the Baksan Underground
Scintillation Telescope (BUST, INR, Russia) in period from 1981 to 2006 (~2.5
solar cycles). The nature of the muon bursts and their probable relation to the
solar cosmic rays is still not quite clear. ATLAS has an excellent muon system
allowing search for similar muon bursts. Within the next few years, when the
LHC and ATLAS should start to operate, an increase in the solar activity is
expected in the new 24th cycle. It increases the probability of finding the
muon bursts from powerful flares. Hence ATLAS has a good opportunity to verify
the relation of muon bursts to the solar cosmic rays.


title: The DMTPC detector

abstract:
  Directional detection of Dark Matter allows for unambiguous direct detection
of WIMPs as well as discrimination between various Dark Matter models in our
galaxy. The DMTPC detector is a low-pressure TPC with optical readout designed
for directional direct detection of WIMPs. By using CF4 gas as the active
material, the detector also has excellent sensitivity to spin-dependent
interactions of Dark Matter on protons.


title: Studying pion effects on the chiral phase transition

abstract:
  We investigate the chiral phase transition at finite temperatures and zero
chemical potential with Dyson-Schwinger equations. Our truncation for the
quark-gluon interaction includes mesonic degrees of freedom, which allows us to
study the impact of the pions on the nature of the phase transition. Within the
present scheme we find a five percent change of the critical temperature due to
the pion backreaction whereas the mean field character of the transition is not
changed.


title:
Negativity of the Coarse Grained Wigner Function as a Measure of Quantal
  Behavior

abstract:
  The negativity of a given state's Wigner function has been proposed as a
measure of quantumness of that state in a unipartite system. This otherwise
physically intuitive and useful phase-space measure however does not yield the
right correspondence principle limit, and also turns out to yield infinite
values for the infinite square well. We show that both these issues can be
sensibly resolved using coarse-graining of the Wigner function.


title:
Metallicities and Radial Velocities of Five Open Clusters Including a
  New Candidate Member of the Monoceros Stream

abstract:
  Near infrared spectra of 133 red giant stars from ten Galactic open clusters
and two Galactic globular clusters spanning 2.2 dex in metallicity and 11 Gyr
in age are presented. We combine this sample with ten clusters from Cole and
collaborators to investigate the Ca II triplet line strengths and their
relation to cluster metallicity and position along the red giant branch. We
show that characterizing the stellar surface gravity using Ks band photometry
(relative to the horizontal branch) taken from the Two Micron All-Sky Survey
allows for metallicity measurements at least as precise as those derived using
V or I band data. This has the great advantage that uniform photometry and
reliable astrometry is available for a large number of clusters. Using Ks band
photometry also reduces the effect of differential reddening within a given
cluster. We find no significant evidence for age or metallicity effects to the
linear Ca II triplet - metallicity relationship over the small range in
magnitudes studied when homogeneous reference metallicities are used. We derive
the first spectroscopic metallicity and new radial velocity estimates for five
open clusters: Berkeley 81, Berkeley 99, IC 1311, King 2, and NGC 7044. King 2
has an anomalous radial velocity compared with the local disk population. We
discuss the possibility that it is part of the Monoceros tidal stream.


title:
The Apparent "Angular Size - Frequency" Dependence in ~3000 Parsec-scale
  Extragalactic Jets

abstract:
  The upper envelope of the amplitude of the VLBI visibility function usually
represents the most compact structural pattern of extragalactic radio sources,
in particular, the "core-jet" morphologies. By fitting the envelope to a
circular Gaussian model in ~3000 parsec-scale core-jet structures, we find that
the apparent angular size shows significant power-law dependence on the
observing frequency (power index n = -0.95 pm 0.37). The dependence is likely
to result from synchrotron self-absorption in the inhomogeneous jet and not the
free-free absorption (n = -2.5), nor the simple scatter broadening (n leq -2).


title:
Preferential concentration vs. clustering in inertial particle transport
  by random velocity fields

abstract:
  The concept of preferential concentration in the transport of inertial
particles by random velocity fields is extended to account for the possibility
of zero correlation time and compressibility of the velocity field. It is shown
that, in the case of an uncorrelated in time random velocity field,
preferential concentration takes the form of a condition on the field history
leading to the current particle positions. This generalized form of
preferential concentration appears to be a necessary condition for clustering
in the uncorrelated in time case. The standard interpretation of preferential
concentration is recovered considering local time averages of the velocity
field. In the compressible case, preferential concentration occurs in regions
of negative divergence of the field. In the incompressible case, it occurs in
regions of simultaneously high strain and negative field skewness.


title:
Characterization of anisotropic nano-particles by using depolarized
  dynamic light scattering in the near field

abstract:
  Light scattering techniques are widely used in many fields of condensed and
sof t matter physics. Usually these methods are based on the study of the
scattered light in the far field. Recently, a new family of near field
detection schemes has been developed, mainly for the study of small angle light
scattering. These techniques are based on the detection of the light intensity
near to the sample, where light scattered at different directions overlaps but
can be distinguished by Fourier transform analysis. Here we report for the
first time data obtained with a dynamic near field scattering instrument,
measuring both polarized and depolarized scattered light. Advantages of this
procedure over the traditional far field detection include the immunity to
stray light problems and the possibility to obtain a large number of
statistical samples for many different wave vectors in a single instantaneous
measurement. By using the proposed technique we have measured the translational
and rotational diffusion coefficients of rod-like colloidal particles. The
obtained data are in very good agreement with the data acquired with a
traditional light scattering apparatus.


title: Understanding the sub-critical transition to turbulence in wall flows

abstract:
  Contrasting with free shear flows presenting velocity profiles with
inflection points which cascade to turbulence in a relatively mild way, wall
bounded flows are deprived of (inertial) instability modes at low Reynolds
numbers and become turbulent in a much wilder way, most often marked by the
coexistence of laminar and turbulent domains at intermediate Reynolds numbers,
well below the range where (viscous) instabilities can show up. There can even
be no unstable mode at all, as for plane Couette flow (pCf) or for Poiseuille
pipe flow (Ppf) that currently are the subject of intense research. Though the
mechanisms involved in the transition to turbulence in wall flows are now
better understood, statistical properties of the transition itself are yet
unsatisfactorily assessed. A review of the situation is given. An alternative
to the temporal theory of the transition to turbulence in terms of chaotic
transients in such globally subcritical flows is proposed, which invokes
spatio-temporal intermittence and the theory of first order (thermodynamic)
phase transitions.


title: Projective metrics and contraction principles for complex cones

abstract:
  In this article, we consider linearly convex complex cones in complex Banach
spaces and we define a new projective metric on these cones. Compared to the
hyperbolic gauge of Rugh, it has the advantage of being explicit, and easier to
estimate. We prove that this metric also satisfies a contraction principle like
Birkhoff's theorem for the Hilbert metric. We are thus able to improve existing
results on spectral gaps for complex matrices. Finally, we compare the
contraction principles for the hyperbolic gauge and our metric on particular
cones, including complexification of Birkhoff cones. It appears that the
contraction principles for our metric and the hyperbolic gauge occur
simultaneously on these cones. However, we get better contraction rates with
our metric.


title: Extremely Compact Massive Galaxies at 1.7<z<3

abstract:
  We measure and analyse the sizes of 82 massive (M >= 10^11 M_Sun) galaxies at
1.7<z<3 utilizing deep HST NICMOS data taken in the GOODS North and South
fields. Our sample provides the first statistical study of massive galaxy sizes
at z>2. We split our sample into disk-like (Sersic index n<=2) and
spheroid-like (Sersic index n>2) galaxies, and find that at a given stellar
mass, disk-like galaxies at z~2.3 are a factor of 2.6+/-0.3 smaller than
present day equal mass systems, and spheroid-like galaxies at the same redshift
are 4.3+/-0.7 times smaller than comparatively massive elliptical galaxies
today. We furthermore show that the stellar mass densities of very massive
galaxies at z~2.5 are similar to present-day globular clusters with values
~2x10^10 M_Sun kpc^-3


title:
DAOSPEC: an automatic code for measuring equivalent widths in
  high-resolution stellar spectra

abstract:
  DAOSPEC is a Fortran code for measuring equivalent widths of absorption lines
in stellar spectra with minimal human involvement. It works with standard FITS
format files and it is designed for use with high resolution (R>15000) and high
signal-to-noise-ratio (S/N>30) spectra that have been binned on a linear
wavelength scale. First, we review the analysis procedures that are usually
employed in the literature. Next, we discuss the principles underlying DAOSPEC
and point out similarities and differences with respect to conventional
measurement techniques. Then experiments with artificial and real spectra are
discussed to illustrate the capabilities and limitations of DAOSPEC, with
special attention given to the issues of continuum placement; radial
velocities; and the effects of strong lines and line crowding. Finally,
quantitative comparisons with other codes and with results from the literature
are also presented.


title: Random Complexes and l^2-Betti Numbers

abstract:
  Uniform spanning trees on finite graphs and their analogues on infinite
graphs are a well-studied area. On a Cayley graph of a group, we show that they
are related to the first $\ell^2$-Betti number of the group. Our main aim,
however, is to present the basic elements of a higher-dimensional analogue on
finite and infinite CW-complexes, which relate to the higher $\ell^2$-Betti
numbers. One consequence is a uniform isoperimetric inequality extending work
of Lyons, Pichot, and Vassout. We also present an enumeration similar to recent
work of Duval, Klivans, and Martin.


title:
Medium-modified evolution of multiparticle production in jets in
  heavy-ion collisions

abstract:
  The energy evolution of medium-modified average multiplicities and
multiplicity fluctuations in quark and gluon jets produced in heavy-ion
collisions is investigated from a toy QCD-inspired model. In this model, we use
modified splitting functions accounting for medium-enhanced radiation of gluons
by a fast parton which propagates through the quark gluon plasma. The leading
contribution of the standard production of soft hadrons is found to be enhanced
by the factor $\sqrt{N_s}$ while next-to-leading order (NLO) corrections are
suppressed by $1/\sqrt{N_s}$, where the nuclear parameter $N_s>1$ accounts for
the induced-soft gluons in the hot medium. The role of next-to-next-to-leading
order corrections (NNLO) is studied and the large amount of medium-induced soft
gluons is found to drastically affect the convergence of the perturbative
series. Our results for such global observables are cross-checked and compared
with their limits in the vacuum and a new method for solving the second
multiplicity correlator evolution equations is proposed.