title: SPAM over Internet Telephony and how to deal with it

abstract:
  In our modern society telephony has developed to an omnipresent service.
People are available at anytime and anywhere. Furthermore the Internet has
emerged to an important communication medium. These facts and the raising
availability of broadband internet access has led to the fusion of these two
services. Voice over IP or short VoIP is the keyword, that describes this
combination. The advantages of VoIP in comparison to classic telephony are
location independence, simplification of transport networks, ability to
establish multimedia communications and the low costs. Nevertheless one can
easily see, that combining two technologies, always brings up new challenges
and problems that have to be solved. It is undeniable that one of the most
annoying facet of the Internet nowadays is email spam. According to different
sources email spam is considered to be 80 to 90 percent of the email traffic
produced. The threat of so called voice spam or Spam over Internet Telephony
(SPIT) is even more fatal, for the annoyance and disturbance factor is much
higher. As instance an email that hits the inbox at 4 p.m. is useless but will
not disturb the user much. In contrast a ringing phone at 4 p.m. will lead to a
much higher disturbance. From the providers point of view both email spam and
voice spam produce unwanted traffic and loss of trust of customers into the
service. In order to mitigate this threat different approaches from different
parties have been developed. This paper focuses on state of the art anti voice
spam solutions, analyses them and reveals their weak points. In the end a SPIT
producing benchmark tool will be introduced, that attacks the presented anti
voice spam solutions. With this tool it is possible for an administrator of a
VoIP network to test how vulnerable his system is.


title:
Towards a complete census of young stars in the solar neighbourhood with
  SkyMapper

abstract:
  In this contribution we outline plans for identifying and characterising
numerous young, low-mass stars within 150 pc of the Sun using the new SkyMapper
telescope and Southern Sky Survey. We aim to learn more about the star
formation history of the solar neighbourhood over the past 5-50 Myr, the
dispersal processes involved, as well as testing pre-main sequence evolutionary
models and the universality of the stellar Inital Mass Function. Searching for
the dispersed halo of low-mass objects predicted to surround the Eta
Chamaeleontis cluster will be one of the first goals of the project.


title: Relaxation of a Single Knotted Ring Polymer

abstract:
  The relaxation of a single knotted ring polymer is studied by Brownian
dynamics simulations. The relaxation rate lambda_q for the wave number q is
estimated by the least square fit of the equilibrium time-displaced correlation
function to a double exponential decay at long times. The relaxation rate
distribution of a single ring polymer with the trefoil knot appears to behave
as lambda_q=A(1/N^)x for q=1 and lambda_q=A'(q/N)^x' for q=2 and 3, where
x=2.61, x'=2.02 and A>A'. The wave number q of the slowest relaxation rate for
each N is given by q=2 for small values of N, while it is given by q=1 for
large values of N. This crossover corresponds to the change of the structure of
the ring polymer caused by the localization of the knotted part to a part of
the ring polymer.


title:
Cooling Dynamics of a Gold Nanoparticle in a Host Medium Under Ultrafast
  Laser Pulse Excitation: A Ballistic-Diffusive Approach

abstract:
  We present a numerical model allowing to determine the electron and lattice
temperature dynamics in a gold nanoparticle under subpicosecond pulsed
excitation, as well as that of the surrounding medium. For this, we have used
the electron-phonon coupling equation in the particle with a source term linked
with the laser pulse, and the ballistic-diffusive equations for heat conduction
in the host medium. Our results show that the heat transfer rate from the
particle to the matrix is significantly smaller than the prediction of
Fourier's law. Consequently, the particle temperature rise is much larger and
its cooling dynamics is much slower than that obtained using Fourier's law,
which is attributed to the nonlocal and nonequilibrium heat conduction in the
vicinity of the nanoparticle. These results are expected to be of great
importance for interpreting pump-probe experiments performed on single
nanoparticles or nanocomposite media.


title: Finite-gap systems, tri-supersymmetry and self-isospectrality

abstract:
  We show that an n-gap periodic quantum system with parity-even smooth
potential admits $2^n-1$ isospectral super-extensions. Each is described by a
tri-supersymmetry that originates from a higher-order differential operator of
the Lax pair and two-term nonsingular decompositions of it; its local part
corresponds to a spontaneously partially broken centrally extended nonlinear
N=4 supersymmetry. We conjecture that any finite-gap system having antiperiodic
singlet states admits a self-isospectral tri-supersymmetric extension with the
partner potential to be the original one translated for a half-period. Applying
the theory to a broad class of finite-gap elliptic systems described by a
two-parametric associated Lame equation, our conjecture is supported by the
explicit construction of the self-isospectral tri-supersymmetric pairs. We find
that the spontaneously broken tri-supersymmetry of the self-isospectral
periodic system is recovered in the infinite period limit.

categories: hep-th cond-mat.other math-ph math.MP nlin.SI quant-ph


title: The Hochschild cohomology ring of the standard Podles quantum sphere

abstract:
  The cup and cap product in twisted Hochschild (co)homology is computed for
the standard quantum 2-sphere and used to construct a cyclic 2-cocycle that
represents the fundamental Hochschild class.


title:
Steady state entanglement in the mechanical vibrations of two dielectric
  membranes

abstract:
  We consider two dielectric membranes suspended inside a Fabry-Perot-cavity,
which are cooled to a steady state via a drive by suitable classical lasers. We
show that the vibrations of the membranes can be entangled in this steady
state. They thus form two mechanical, macroscopic degrees of freedom that share
steady state entanglement.


title: Optical spectra of the heavy fermion uniaxial ferromagnet UGe$_2$

abstract:
  We report a detailed study of UGe$_{2}$ single crystals using infrared
reflectivity and spectroscopic ellipsometry. The optical conductivity suggests
the presence of a low frequency interband transition and a narrow free-carrier
response with strong frequency dependence of the scattering rate and effective
mass. We observe sharp changes in the low frequency mass and scattering rate
below the upper ferromagnetic transition $T_C = 53 K$. The characteristic
changes are exhibited most strongly at an energy scale of around 12 meV (100
cm$^{-1}$). They recover their unrenormalized value above $T_C$ and for $\omega
>$ 40 meV. In contrast no sign of an anomaly is seen at the lower transition
temperature of unknown nature $T_x \sim$ 30 K, observed in transport and
thermodynamic experiments. In the ferromagnetic state we find signatures of a
strong coupling to the longitudinal magnetic excitations that have been
proposed to mediate unconventional superconductivity in this compound.


title:
Fine-scale statistics of temperature and its derivatives in convective
  turbulence

abstract:
  We study the fine-scale statistics of temperature and its derivatives in
turbulent Rayleigh-Benard convection. Direct numerical simulations are carried
out in a cylindrical cell with unit aspect ratio filled with a fluid with
Prandtl number equal to 0.7 for Rayleigh numbers between 10^7 and 10^9. The
probability density function of the temperature or its fluctuations is found to
be always non-Gaussian. The asymmetry and strength of deviations from the
Gaussian distribution are quantified as a function of the cell height. The
deviations of the temperature fluctuations from the local isotropy, as measured
by the skewness of the vertical derivative of the temperature fluctuations,
decrease in the bulk, but increase in the thermal boundary layer for growing
Rayleigh number, respectively. Similar to the passive scalar mixing, the
probability density function of the thermal dissipation rate deviates
significantly from a log-normal distribution. The distribution is fitted well
by a stretched exponential form. The tails become more extended with increasing
Rayleigh number which displays an increasing degree of small-scale
intermittency of the thermal dissipation field for both the bulk and the
thermal boundary layer. We find that the thermal dissipation rate due to the
temperature fluctuations is not only dominant in the bulk of the convection
cell, but also yields a significant contribution to the total thermal
dissipation in the thermal boundary layer. This is in contrast to the ansatz
used in scaling theories and can explain the differences in the scaling of the
total thermal dissipation rate with respect to the Rayleigh number.


title:
Near-Field Heat Transfer Percolation in Nanoparticles based Composite
  Media

abstract:
  Near-field radiative heat transfer is investigated in composite media
including nanoparticles. By modeling pair interactions only, the effective
thermal conductivity due to near field radiation is calculated based on a
thermal nodes model. We highlight the onset of a Near-Field percolation
occurring much earlier than the mechanical percolation at critical volume
fraction f=0.033. This 15 mechanism drastically increases the thermal
conductivity even at low volume fractions. It also indicates a simple
experimental protocol to prove Near-Field contact.


title:
The analysis of reactions $\pi N\to two mesons + N$ within reggeon
  exchanges. 2. Basic formulas for fit

abstract:
  We present technical aspects of the fitting procedure given in the paper V.V.
Anisovich and A.V. Sarantsev {\it The analysis of reactions $\pi N\to two
mesons + N$ within reggeon exchanges. 1. Fit and results.} (arxiv:0806.1601v1)


title:
Some Critical Issues for the "Equation-Free" Approach to Multiscale
  Modeling

abstract:
  The "equation-free'' approach has been proposed in recent years as a general
framework for developing multiscale methods to efficiently capture the
macroscale behavior of a system using only the microscale models. In this
paper, we take a close look at some of the algorithms proposed under the
"equation-free'' umbrella, the projective integrators and the patch dynamics.
We discuss some very simple examples in the context of the "equation-free''
approach. These examples seem to indicate that while its general philosophy is
quite attractive and indeed similar to many other approaches in concurrent
multiscale modeling, there are severe limitations to the specific
implementation proposed by the equation-free approach.


title:
Non-Fourier heat transport in metal-dielectric core-shell nanoparticles
  under ultrafast laser pulse excitation

abstract:
  Relaxation dynamics of embedded metal nanoparticles after ultrafast laser
pulse excitation is driven by thermal phenomena of different origins the
accurate description of which is crucial for interpreting experimental results:
hot electron gas generation, electron-phonon coupling, heat transfer to the
particle environment and heat propagation in the latter. Regardingthis last
mechanism, it is well known that heat transport in nanoscale structures and/or
at ultrashort timescales may deviate from the predictions of the Fourier law.
In these cases heat transport may rather be described by the Boltzmann
transport equation. We present a numerical model allowing us to determine the
electron and lattice temperature dynamics in a spherical gold nanoparticle core
under subpicosecond pulsed excitation, as well as that of the surrounding shell
dielectric medium. For this, we have used the electron-phonon coupling equation
in the particle with a source term linked with the laser pulse absorption, and
the ballistic-diffusive equations for heat conduction in the host medium.
Either thermalizing or adiabatic boundary conditions have been considered at
the shell external surface. Our results show that the heat transfer rate from
the particle to the matrix can be significantly smaller than the prediction of
Fourier's law. Consequently, the particle temperature rise is larger and its
cooling dynamics might be slower than that obtained by using Fourier's law.
This difference is attributed to the nonlocal and nonequilibrium heat
conduction in the vicinity of the core nanoparticle. These results are expected
to be of great importance for analyzing pump-probe experiments performed on
single nanoparticles or nanocomposite media.


title:
A view of the sub-mJy populations, modelling and perspectives for future
  deep surveys

abstract:
  We use deep multi-colour (UBVRIJK) images mostly taken in the framework of
the ESO Deep Public Survey (DPS) to optically identify and derive photometric
redshifts for a complete sample of 131 radio sources with S>0.4 mJy, observed
at both 1.4 and 5 GHz as part of the ATESP radio survey. The availability of
multi-wavelength radio and optical information is exploited to infer the
physical properties of the faint radio population. In particular we find that,
considering both early-type galaxies and quasars as sources with an active
nucleus, AGNs largely dominate our sample sub-mJy sample (78%). Further
radio/optical analysis of such AGN component has revealed a somewhat unexpected
class of flat/inverted-spectrum sources with low radio-to-optical ratios
(R<100), which are preferentially identified with early-type galaxies. Such
sources are quite compact (d<10-30 kpc), suggesting core-dominated radio
emission triggered by low luminosity AGNs. This intriguing class of objects
deserves further analysis, and new higher resolution radio observations are
currently under way. In parallel we are developing radio source models, for
both the AGN and the star-forming components of the sub-mJy radio pupulation.
Here we discuss the first results.


title: Heavy Vectors in Higgs-less models

abstract:
  One or more heavy spin-1 fields may replace the Higgs boson in keeping
perturbative unitarity up to a few TeV. By means of two prototype chiral models
for the heavy spin-1 bosons, a "composite" model or a "gauge" model, we discuss
if and how the sole exchange of the same fields can also account for the
ElectroWeak Precision Tests. While this proves impossible in the gauge model,
the composite model hints to a positive solution, which we exploit to constrain
the phenomenological properties of the heavy vectors.


title: Computable bounds for the discrimination of Gaussian states

abstract:
  By combining the Minkowski inequality and the quantum Chernoff bound, we
derive easy-to-compute upper bounds for the error probability affecting the
optimal discrimination of Gaussian states. In particular, these bounds are
useful when the Gaussian states are unitarily inequivalent, i.e., they differ
in their symplectic invariants.

categories: quant-ph math-ph math.MP physics.data-an


title:
Parity and Time-Reversal Breaking Effects on Resonant X-Ray Scattering
  at the Fe Pre-K-Edge in Magnetite

abstract:
  We study noncentrosymmetric effects on resonant x-ray scattering (RXS) in
magnetite. The noncentrosymmetry at A sites in spinel structure makes the 4p
states strongly hybridize with the 3d states through neighboring oxygen 2p
states, giving rise to the non-vanishing contribution of the dipole-quadrupole
(E1-E2) process in the RXS spectra. We substantiate this observation by
introducing a microscopic model of a FeO_4 cluster with multiplets and the 4p
band. We show that the hybridization changes its sign between two kinds of A
sites and accordingly the local amplitude from the E1-E2 process changes its
sign, resulting in non-vanishing RXS intensities at forbidden spots (002) and
(006) in the pre-edge region in agreement with the experiment. A large
dependence of the pre-edge intensity on the direction of the applied magnetic
field is predicted as a consequence of breaking both centrosymmetry and
time-reversal symmetry. Furthermore we analyze the intensity difference between
two opposite directions of the applied magnetic field at the allowed spot (222)
in connection with the experiment. We obtain the intensity difference of a
"dispersion" form, which resembles the observed spectra at the Mn pre-K-edge in
MnCr_2O_4 but is quite different from the observed one in magnetite. Although
the observed spectra are claimed to arise from "magnetoelectric" amplitude, we
argue that this claim has no ground.


title:
Atom-atom correlations and relative number squeezing in dissociation of
  spatially inhomogeneous molecular condensates

abstract:
  We study atom-atom correlations and relative number squeezing in the
dissociation of a Bose-Einstein condensate (BEC) of molecular dimers made of
either bosonic or fermionic atom pairs. Our treatment addresses the role of the
spatial inhomogeneity of the molecular BEC on the strength of correlations in
the short time limit. We obtain explicit analytic results for the
density-density correlation functions in momentum space, and show that the
correlation widths and the degree of relative number squeezing are determined
merely by the shape of the molecular condensate.


title:
A Direct Approach to the Electromagnetic Casimir Energy in a Rectangular
  Waveguide

abstract:
  In this paper we compute the leading order Casimir energy for the
electromagnetic field (EM) in an open ended perfectly conducting rectangular
waveguide in three spatial dimensions by a direct approach. For this purpose we
first obtain the second quantized expression for the EM field with boundary
conditions which would be appropriate for a waveguide. We then obtain the
Casimir energy by two different procedures. Our main approach does not contain
any analytic continuation techniques. The second approach involves the routine
zeta function regularization along with some analytic continuation techniques.
Our two approaches yield identical results. This energy has been calculated
previously for the EM field in a rectangular waveguide using an indirect
approach invoking analogies between EM fields and massless scalar fields, and
using complicated analytic continuation techniques, and the results are
identical to ours. We have also calculated the pressures on different sides and
the total Casimir energy per unit length, and plotted these quantities as a
function of the cross-sectional dimensions of the waveguide. We also present a
physical discussion about the rather peculiar effect of the change in the sign
of the pressures as a function of the shape of the cross-sectional area.


title: Particle dynamics on AdS_2 x S^2 background with two-form flux

abstract:
  Different aspects of particle dynamics on AdS_2 x S^2 background with
two-form flux are discussed. These include solution of equations of motion, a
canonical transformation to conformal mechanics and an N=4 supersymmetric
extension.


title: Sommerfeld corrections to type-II and III leptogenesis

abstract:
  We study thermal leptogenesis from decays of the electroweak triplets that
mediate neutrino masses in type-II and type-III see-saw. We find that
Sommerfeld corrections reduce the baryon asymmetry by ~30%, and that successful
leptogenesis needs triplets heavier than 1.6 TeV, beyond the discovery reach of
LHC.


title: Bayesian outlier detection in Capital Asset Pricing Model

abstract:
  We propose a novel Bayesian optimisation procedure for outlier detection in
the Capital Asset Pricing Model. We use a parametric product partition model to
robustly estimate the systematic risk of an asset. We assume that the returns
follow independent normal distributions and we impose a partition structure on
the parameters of interest. The partition structure imposed on the parameters
induces a corresponding clustering of the returns. We identify via an
optimisation procedure the partition that best separates standard observations
from the atypical ones. The methodology is illustrated with reference to a real
data set, for which we also provide a microeconomic interpretation of the
detected outliers.


title: Geodesically Complete Lorentzian Metrics on Some Homogeneous 3 Manifolds

abstract:
  In this work it is shown that a necessary condition for the completeness of
the geodesics of left invariant pseudo-Riemannian metrics on Lie groups is also
sufficient in the case of 3-dimensional unimodular Lie groups, and not
sufficient for 3-dimensional non unimodular Lie groups. As a consequence it is
possible to identify, amongst the compact locally homogeneous Lorentzian
3-manifolds with non compact (local) isotropy group, those that are
geodesically complete.


title:
Charge-memory effect in a polaron model: equation-of-motion method for
  Green functions

abstract:
  We analyze a single-level quantum system placed between metallic leads and
strongly coupled to a localized vibrational mode, which models a singlemolecule
junction or an STM setup. We consider a polaron model describing the
interaction between electronic and vibronic degrees of freedom and develop and
examine different truncation schemes in the equation-of-motion method within
the framework of non-equilibrium Green functions. We show that upon applying
gate or bias voltage, it is possible to observe charge-bistability and
hysteretic behavior which can be the basis of a charge-memory element. We
further perform a systematic analysis of the bistability behaviour of the
system for different internal parameters such as the electron-vibron and the
lead-molecule coupling strength.


title: Formulas for the amplitude of the van der Pol limit cycle

abstract:
  The limit cycle of the van der Pol oscillator, $\ddot{x}+ \epsilon (x^2-1)
\dot{x} + x =0$, is studied in the plane $(x,\dot{x})$ by applying the homotopy
analysis method. A recursive set of formulas that approximate the amplitude and
form of this limit cycle for the whole range of the parameter $\epsilon$ is
obtained. These formulas generate the amplitude with an error less than 0.1%.
To our knowledge, this is the first time where an analytical approximation of
the amplitude of the van der Pol limit cycle, with validity from the weakly up
to the strongly nonlinear regime, is given.


title: Friction and dilatancy in immersed granular matter

abstract:
  The friction of a sliding plate on a thin immersed granular layer obeys
Amonton-Coulomb law. We bring to the fore a large set of experimental results
which indicate that, over a few decades of values, the effective dynamical
friction-coefficient depends neither on the viscosity of the interstitial fluid
nor on the size of beads in the sheared layer, which bears out the analogy with
the solid-solid friction in a wide range of experimental parameters. We
accurately determine the granular-layer dilatancy, which dependance on the
grain size and slider velocity can be qualitatively accounted by considering
the rheological behaviour of the whole slurry. However, additional results,
obtained after modification of the grain surface by a chemical treatment,
demonstrate that the theoretical description of the flow properties of granular
matter, even immersed, requires the detailed properties of the grain surface to
be taken into account.


title: Data-Complexity of the Two-Variable Fragment with Counting Quantifiers

abstract:
  The data-complexity of both satisfiability and finite satisfiability for the
two-variable fragment with counting is NP-complete; the data-complexity of both
query-answering and finite query-answering for the two-variable guarded
fragment with counting is co-NP-complete.


title: Counterpropagating Two-Soliton Solutions in the FPU Lattice

abstract:
  We study the interaction of small amplitude, long wavelength solitary waves
in the Fermi-Pasta-Ulam model with general nearest-neighbor interaction
potential. We establish global-in-time existence and stability of
counter-propagating solitary wave solutions. These solutions are close to the
linear superposition of two solitary waves for large positive and negative
values of time; for intemediate values of time these solutions describe the
interaction of two counterpropagating pulses. These solutions are stable with
respect to perturbations in $\ell^2$ and asymptotically stable with respect to
perturbations which decay exponentially at spatial $\pm \infty$.}


title: CRISP Spectropolarimetric Imaging of Penumbral Fine Structure

abstract:
  We discuss penumbral fine structure in a small part of a pore, observed with
the CRISP imaging spectropolarimeter at the Swedish 1-m Solar Telescope (SST),
close to its diffraction limit of 0.16 arcsec. Milne-Eddington inversions
applied to these Stokes data reveal large variations of field strength and
inclination angle over dark-cored penumbral intrusions and a dark-cored light
bridge. The mid-outer part of this penumbra structure shows 0.3 arcsec wide
spines, separated by 1.6 arcsec (1200 km) and associated with 30 deg
inclination variations. Between these spines, there are no small-scale magnetic
structures that easily can be be identified with individual flux tubes. A
structure with nearly 10 deg more vertical and weaker magnetic field is seen
midways between two spines. This structure is co-spatial with the brightest
penumbral filament, possibly indicating the location of a convective upflow
from below.


title: D2 to D2

abstract:
  Starting from maximally supersymmetric (2+1)d Yang-Mills theory and using a
duality transformation due to de Wit, Nicolai and Samtleben, we obtain the
ghost-free Lorentzian 3-algebra theory that has recently been proposed to
describe M2-branes. Our derivation does not invoke any properties of
3-algebras. Being derivable from SYM, the final theory is manifestly equivalent
to it on-shell and should not be thought of as the IR limit that describes
M2-branes, though it does have enhanced R-symmetry as well as superconformal
symmetry off-shell.


title:
Toward a combination rule to deal with partial conflict and specificity
  in belief functions theory

abstract:
  We present and discuss a mixed conjunctive and disjunctive rule, a
generalization of conflict repartition rules, and a combination of these two
rules. In the belief functions theory one of the major problem is the conflict
repartition enlightened by the famous Zadeh's example. To date, many
combination rules have been proposed in order to solve a solution to this
problem. Moreover, it can be important to consider the specificity of the
responses of the experts. Since few year some unification rules are proposed.
We have shown in our previous works the interest of the proportional conflict
redistribution rule. We propose here a mixed combination rule following the
proportional conflict redistribution rule modified by a discounting procedure.
This rule generalizes many combination rules.


title: Ferrimagnetism of MnV_2O_4 spinel

abstract:
  The spinel MnV_2O_4 is a two-sublattice ferrimagnet, with site A occupied by
the Mn^{2+} ion and site B by the V^{3+} ion. The magnon of the system, the
transversal fluctuation of the total magnetization, is a complicated mixture of
the sublattice A and B transversal magnetic fluctuations. As a result, the
magnons' fluctuations suppress in a different way the manganese and vanadium
magnetic orders and one obtains two phases. At low temperature (0,T^*) the
magnetic orders of the Mn and V ions contribute to the magnetization of the
system, while at the high temperature (T^*,T_N), the vanadium magnetic order is
suppressed by magnon fluctuations, and only the manganese ions have non-zero
spontaneous magnetization. A modified spin-wave theory is developed to describe
the two phases and to calculate the magnetization as a function of temperature.
The anomalous $M(T)$ curve reproduces the experimentally obtained ZFC
magnetization.


title: Generalized synchronization of chaos in autonomous systems

abstract:
  We extend the concept of generalized synchronization of chaos, a phenomenon
that occurs in driven dynamical systems, to the context of autonomous
spatiotemporal systems. It means a situation where the chaotic state variables
in an autonomous system can be synchronized to each other but not to a coupling
function defined from them. The form of the coupling function is not crucial;
it may not depend on all the state variables nor it needs to be active for all
times for achieving generalized synchronization. The procedure is based on the
analogy between a response map subject to an external drive acting with a
probability p and an autonomous system of coupled maps where a global
interaction between the maps takes place with this same probability. It is
shown that, under some circumstances, the conditions for stability of
generalized synchronized states are equivalent in both types of systems. Our
results reveal the existence of similar minimal conditions for the emergence of
generalized synchronization of chaos in driven and in autonomous spatiotemporal
systems.


title:
Effect of feedback on the control of a two-level dissipative quantum
  system

abstract:
  We show that it is possible to modify the stationary state by a feedback
control in a two-level dissipative quantum system. Based on the geometric
control theory, we also analyze the effect of the feedback on the time-optimal
control in the dissipative system governed by the Lindblad master equation.
These effects are reflected in the function $\Delta_A(\vec{x})$ and
$\Delta_B(\vec{x})$ that characterize the optimal trajectories, as well as the
switching function $\Phi(t)$ and $\theta(t),$ which characterize the switching
point in time for the time-optimal trajectory.


title: A New Approach for Simulating Galaxy Cluster Properties

abstract:
  We describe a subgrid model for including galaxies into hydrodynamical
cosmological simulations of galaxy cluster evolution. Each galaxy construct- or
galcon- is modeled as a physically extended object within which star formation,
galactic winds, and ram pressure stripping of gas are modeled analytically.
Galcons are initialized at high redshift (z~3) after galaxy dark matter halos
have formed but before the cluster has virialized. Each galcon moves
self-consistently within the evolving cluster potential and injects mass,
metals, and energy into intracluster (IC) gas through a well-resolved spherical
interface layer. We have implemented galcons into the Enzo adaptive mesh
refinement code and carried out a simulation of cluster formation in a
LambdaCDM universe. With our approach, we are able to economically follow the
impact of a large number of galaxies on IC gas. We compare the results of the
galcon simulation with a second, more standard simulation where star formation
and feedback are treated using a popular heuristic prescription. One advantage
of the galcon approach is explicit control over the star formation history of
cluster galaxies. Using a galactic SFR derived from the cosmic star formation
density, we find the galcon simulation produces a lower stellar fraction, a
larger gas core radius, a more isothermal temperature profile, and a flatter
metallicity gradient than the standard simulation, in better agreement with
observations.


title: H\"older Regularity of Two-Dimensional Almost-Minimal Sets in $\R^n$

abstract:
  We give a different and probably more elementary proof of a good part of Jean
Taylor's regularity theorem for Almgren almost-minimal sets of dimension 2 in
$\R^3$. We use this opportunity to settle some details about almost-minimal
sets, extend a part of Taylor's result to almost-minimal sets of dimension 2 in
$\R^n$, and give the expected characterization of the closed sets $E$ of
dimension 2 in $\R^3$ that are minimal, in the sense that $H^2(E\setminus F)
\leq H^2(F\setminus E)$ for every closed set $F$ such that there is a bounded
set $B$ so that $F=E$ out of $B$ and $F$ separates points of $\R^3 \setminus B$
that $E$ separates.


title:
Planetesimal formation around the snow line in MRI-driven turbulent
  protoplanetary disks

abstract:
  The formation of planetesimals in protoplanetary disks due to collisional
sticking of smaller dust aggregates has to face at least two severe obstacles,
namely the rapid loss of material due to radial inward drift and particle
fragmentation due to destructive collisions. We present a scenario to
circumvent these two hurdles. Our dust evolution model involves two main
mechanisms. First, we consider a disk with a dead zone. In an almost laminar
region close to the midplane, the relative velocities of the turbulent
particles are comparatively small, which decreases the probability of
destructive particle collisions. Second, turbulence is not the only source of
violent relative particle velocities, because high radial drift speeds can also
lead to boulder fragmentation. For this reason, we focus additionally on the
snow line. Evaporation fronts can be associated with gas pressure maxima in
which radial drift basically vanishes. This implies that particle fragmentation
becomes even less likely. Our simulation results suggest that particles can
overcome the fragmentation barrier. We find that boulders of several 100 m can
form within only a few thousand years.


title: The radio spectrum and magnetic field structure of SNR HB3

abstract:
  Evidence for a spectral flattening of the supernova remnant (SNR) HB3
(G132.7+1.3) was recently claimed in literature based on previously published
total flux density data, and the flattening was further interpreted as the
discovery of thermal bremsstrahlung emission in the shell of HB3. A spectral
flattening has never been observed from any SNR before. Reliable observations
of HB3 at frequencies above 3000 MHz are crucial to confirm such a spectral
behaviour. We extracted 4800 MHz total intensity and polarisation data of HB3
from the Sino-German 6 cm polarisation survey of the Galactic plane made with
the Urumqi 25 m telescope, and analysed the spectrum of HB3, together with
Effelsberg data at 1408 MHz and 2675 MHz. We found an overall spectral index of
HB3 of alpha=-0.61+-0.06 between 1408 MHz and 4800 MHz, similar to the index at
lower frequencies. There is no spectral flattening at high frequencies. We
detected strong polarised emission from HB3 at 4800 MHz. Our 4800 MHz data show
a tangential field orientation in the HB3 shell.


title: Formation of dynamical structures in relativistic jets: the FRI case

abstract:
  Strong observational evidence indicates that all extragalactic jets
associated with AGNs move at relativistic speed up to 100 pc - 1 kpc scales
from the nucleus. At larger distances, reflecting the Fanaroff-Riley radio
source classification, we observe an abrupt deceleration in FR-I jets while
relativistic motions persist up to Mpc scale in FR-II. Moreover, VLBI
observations of some object like B2 1144+35, Mrk501 and M87 show limb
brightening of the jet radio emission at the parsec scale. This effect is
interpreted kinematically as due to the presence of a deboosted central spine
at high Lorentz factor and of a weakly relativistic external layer. In this
paper we investigate whether these effects can be interpreted by a breaking of
the collimated flow by external medium entrainment favored by shear
instabilities, namely Kelvin-Helmholtz instabilities. We examine in details the
physical conditions under which significant deceleration of a relativistic flow
is produced. We investigate the phenomenon by means of high-resolution
three-dimensional relativistic hydrodynamic simulations using the PLUTO code
for computational astrophysics. We find that the parameter of utmost importance
in determining the instability evolution and the entrainment properties is the
ambient/jet density contrast. We show that lighter jets suffer stronger slowing
down in the external layer than in the central part and conserve a central
spine at high Lorentz factor. Our model is verified by constructing synthetic
emission maps from the numerical simulations that compare reasonably well with
VLBI observations of the inner part of FR-I sources.


title: Effect of spatial structure on the evolution of cooperation

abstract:
  Spatial structure is known to have an impact on the evolution of cooperation,
and so it has been intensively studied during recent years. Previous work has
shown the relevance of some features, such as the synchronicity of the
updating, the clustering of the network or the influence of the update rule.
This has been done, however, for concrete settings with particular games,
networks and update rules, with the consequence that some contradictions have
arisen and a general understanding of these topics is missing in the broader
context of the space of 2x2 games. To address this issue, we have performed a
systematic and exhaustive simulation in the different degrees of freedom of the
problem. In some cases, we generalize previous knowledge to the broader context
of our study and explain the apparent contradictions. In other cases, however,
our conclusions refute what seems to be established opinions in the field, as
for example the robustness of the effect of spatial structure against changes
in the update rule, or offer new insights into the subject, e.g. the relation
between the intensity of selection and the asymmetry between the effects on
games with mixed equilibria.


title: Haar Shifts, Commutators, and Hankel Operators

abstract:
  Hankel operators lie at the junction of analytic and real-variables. We will
explore this junction, from the point of view of Haar shifts and commutators.
An decomposition of the commutator [H,b] into paraproducts is presented.


title: Instabilities in Thermal Gravity with a Cosmological Constant

abstract:
  It is shown that in quantum gravity at finite temperature, the effective
potential evaluated in the tadpole approximation can have a local minimum below
a certain critical temperature. However, when the leading higher order thermal
loop corrections are included, one finds that no static solution exists at high
temperature.


title:
Confidence Sets Based on Penalized Maximum Likelihood Estimators in
  Gaussian Regression

abstract:
  Confidence intervals based on penalized maximum likelihood estimators such as
the LASSO, adaptive LASSO, and hard-thresholding are analyzed. In the
known-variance case, the finite-sample coverage properties of such intervals
are determined and it is shown that symmetric intervals are the shortest. The
length of the shortest intervals based on the hard-thresholding estimator is
larger than the length of the shortest interval based on the adaptive LASSO,
which is larger than the length of the shortest interval based on the LASSO,
which in turn is larger than the standard interval based on the maximum
likelihood estimator. In the case where the penalized estimators are tuned to
possess the `sparsity property', the intervals based on these estimators are
larger than the standard interval by an order of magnitude. Furthermore, a
simple asymptotic confidence interval construction in the `sparse' case, that
also applies to the smoothly clipped absolute deviation estimator, is
discussed. The results for the known-variance case are shown to carry over to
the unknown-variance case in an appropriate asymptotic sense.


title: Three Modes of Metal-Enriched Star Formation in the Early Universe

abstract:
  Simulations of the formation of Population III (Pop III) stars suggest that
they were much more massive than the Pop II and Pop I stars observed today.
This is due to the collapse dynamics of metal-free gas, which is regulated by
the radiative cooling of molecular hydrogen. We study how the collapse of gas
clouds is altered by the addition of metals to the star-forming environment by
performing a series of simulations of pre-enriched star formation at various
metallicities. For metallicities below the critical metallicity, Z_cr, collapse
proceeds similarly to the metal-free case, and only massive objects form. For
metallicities well above Z_cr, efficient cooling rapidly lowers the gas
temperature to the temperature of the CMB. The gas is unable to radiatively
cool below the CMB temperature, and becomes thermally stable. For high
metallicities, Z >= 10^-2.5 Zsun, this occurs early in the evolution of the gas
cloud, when the density is still relatively low. The resulting cloud-cores show
little or no fragmentation, and would most likely form massive stars. If the
metallicity is not vastly above Z_cr, the cloud cools efficiently but does not
reach the CMB temperature, and fragmentation into multiple objects occurs. We
conclude that there were three distinct modes of star formation at high
redshift (z >= 4): a `primordial' mode, producing massive stars (10s to 100s
Msun) at very low metallicities (Z <= 10^-3.75 Zsun); a CMB-regulated mode,
producing moderate mass (10s of Msun) stars at high metallicites (Z >= 10^-2.5
Zsun at redshift z ~ 15-20); and a low-mass (a few Msun) mode existing between
those two metallicities. As the universe ages and the CMB temperature
decreases, the range of the low mass mode extends to higher metallicities,
eventually becoming the only mode of star formation. (Abridged)


title:
Nonlinear current-voltage behavior and electrically driven phase
  transition in charge frustrated LuFe2O4

abstract:
  Electric transport measurements of the charge frustrated LuFe2O4, in which
the charge ordering (CO) and electronic ferroelectricity are found, reveal
strong nonlinear electric conduction upon application of electrical field in
both single crystalline and polycrystalline samples. The threshold electric
fields (Et) in single crystalline LuFe2O4 are estimated respectively to be
about 60V/cm and 10V/cm with E parallel and perpendicular to the c-axis
direction. Experimental measurements also demonstrate that the I-V nonlinearity
increases quickly with lowering temperature. Furthermore, our in-situ TEM
investigations evidently reveal that the nonlinear I-V behavior is
intrinsically in correlation with a current driven charge ordering
insulator-metal transition, and the applied electrical field triggers a visible
CO collapse recognizable as the fading of satellite spots of the CO
modulations.


title: Self-Organization and Complex Networks

abstract:
  In this chapter we discuss how the results developed within the theory of
fractals and Self-Organized Criticality (SOC) can be fruitfully exploited as
ingredients of adaptive network models. In order to maintain the presentation
self-contained, we first review the basic ideas behind fractal theory and SOC.
We then briefly review some results in the field of complex networks, and some
of the models that have been proposed. Finally, we present a self-organized
model recently proposed by Garlaschelli et al. [Nat. Phys. 3, 813 (2007)] that
couples the fitness network model defined by Caldarelli et al. [Phys. Rev.
Lett. 89, 258702 (2002)] with the evolution model proposed by Bak and Sneppen
[Phys. Rev. Lett. 71, 4083 (1993)] as a prototype of SOC. Remarkably, we show
that the results obtained for the two models separately change dramatically
when they are coupled together. This indicates that self-organized networks may
represent an entirely novel class of complex systems, whose properties cannot
be straightforwardly understood in terms of what we have learnt so far.

categories: cond-mat.dis-nn cond-mat.stat-mech nlin.AO physics.soc-ph


title: Lindemann Parameters for solid Membranes focused on Carbon Nanotubes

abstract:
  Temperature fluctuations in the normal direction of planar crystals such as
graphene are quite violent and may be expected to influence strongly their
melting properties. In particular, they will modify the Lindemann melting
criterium. We calculate this modification in a self-consistent Born
approximation. The result is applied to graphene and its wrapped version
represented by single-walled carbon nanotubes (SWNTs). It is found that the
out-of-plane fluctuations dominate over the in-plane fluctuations. This makes
strong restrictions to possible Lindemann parameters. Astonishing we find that
these large out-of-plane fluctuations have only a small influence upon the
melting temperature.


title:
Curious Variables Experiment (CURVE). RZ LMi - the most active SU UMa
  star

abstract:
  We report extensive photometry of the frequently outbursting dwarf nova RZ
Leo Minoris. During two seasons of observations we detected 12 superoutbursts
and 7 normal outbursts. The V magnitude of the star varied in range from 16.5
to 13.9 mag. The superoutbursts occur quite regularly flashing every 19.07(4)
days and lasting slightly over 10 days. The average interval between two
successive normal outbursts is 4.027(3) days. The mean superhump period
observed during the superoutbursts is 0.059396(4) days (85.530(6) min). The
period of the superhumps was constant except for one superoutburst when it
increased with a rate of $\dot P/P_{\rm sh} = 7.6(1.9)\cdot 10^{-5}$. Our
observations indicate that RZ LMi goes into long intervals of showing permanent
superhumps which are observed both in superoutbursts and quiescence. This may
indicate that decoupling of thermal and tidal instabilities play important role
in ER UMa systems. No periodic light variations which can be connected with
orbital period of the binary were seen, thus the mass ratio and evolutionary
status of RZ LMi are still unknown.


title:
Phase Behavior of Poly(N-isopropylacrylamide) Nanogel dispersions:
  Temperature Dependent Particle Size and Interactions

abstract:
  The phase behavior of poly (N-isopropylacrylamide) nanoparticles dispersed in
aqueous medium is investigated as a function of temperature using static and
dynamic light scattering techniques. The diameter, d of the particles, as
determined by dynamic light scattering measurements on dilute dispersion showed
a decrease in size from 273 nm at 25C to 114 nm at 40C as function of
temperature with a sudden collapse of particle volume (volume phase transition)
at 32.4C. Further this nanoparticle dispersion is found to turn turbid beyond
volume phase transition. Static light scattering measurements on samples with
intermediate concentration and high concentration showed liquid-like order and
crystalline order respectively. The intensity of the Bragg peak of the
crystallized sample when monitored as a function of temperature showed crystal
to liquid transition at 26.2C and a fluid to fluid transition at 31C. The
occurrence of melting at a volume fraction of 0.85 and the absence of change in
number density across the fluid-to-fluid transition suggest that interparticle
interaction is repulsive soft-sphere below the volume phase transition. The
reported results on the phase behavior of poly(N-isopropylacrylamide) nanogel
suspensions are discussed in the light of the present results.


title: Bounds on the Sum Capacity of Synchronous Binary CDMA Channels

abstract:
  In this paper, we obtain a family of lower bounds for the sum capacity of
Code Division Multiple Access (CDMA) channels assuming binary inputs and binary
signature codes in the presence of additive noise with an arbitrary
distribution. The envelope of this family gives a relatively tight lower bound
in terms of the number of users, spreading gain and the noise distribution. The
derivation methods for the noiseless and the noisy channels are different but
when the noise variance goes to zero, the noisy channel bound approaches the
noiseless case. The behavior of the lower bound shows that for small noise
power, the number of users can be much more than the spreading gain without any
significant loss of information (overloaded CDMA). A conjectured upper bound is
also derived under the usual assumption that the users send out equally likely
binary bits in the presence of additive noise with an arbitrary distribution.
As the noise level increases, and/or, the ratio of the number of users and the
spreading gain increases, the conjectured upper bound approaches the lower
bound. We have also derived asymptotic limits of our bounds that can be
compared to a formula that Tanaka obtained using techniques from statistical
physics; his bound is close to that of our conjectured upper bound for large
scale systems.


title: Uncertainty relations in terms of Tsallis entropy

abstract:
  Uncertainty relations emerging from the Tsallis entropy are derived and
discussed. In particular we found a positively defined function that saturates
the so called entropic inequalities for entropies characterizing the physical
states under consideration.


title:
Synthesis and Microstructural Studies of Iron Based LaO1-xFxFeAs
  Superconducting Materials

abstract:
  We report on the synthesis and microstructural studies of fluorine based iron
doped superconductors. We have successfully synthesized the fluorine based new
superconducting material LaO1-xFxFeAs by choosing comparatively lower
temperature and longer synthesis duration. The superconducting transition
temperature that we have achieved is 27.5 K which is observed at doping level
of x=0.2. The structural microstructural characterizations have been done by
employing XRD, SEM and TEM techniques. The SEM and TEM micrographs reveal the
layered structure.


title:
Tailoring the atomic structure of graphene nanoribbons by STM
  lithography

abstract:
  The practical realization of nano-scale electronics faces two major
challenges: the precise engineering of the building blocks and their assembly
into functional circuits. In spite of the exceptional electronic properties of
carbon nanotubes only basic demonstration-devices have been realized by
time-consuming processes. This is mainly due to the lack of selective growth
and reliable assembly processes for nanotubes. However, graphene offers an
attractive alternative. Here we report the patterning of graphene nanoribbons
(GNRs) and bent junctions with nanometer precision, well-defined widths and
predetermined crystallographic orientations allowing us to fully engineer their
electronic structure using scanning tunneling microscope (STM) lithography. The
atomic structure and electronic properties of the ribbons have been
investigated by STM and tunneling spectroscopy measurements. Opening of
confinement gaps up to 0.5 eV, allowing room temperature operation of GNR-based
devices, is reported. This method avoids the difficulties of assembling
nano-scale components and allows the realization of complete integrated
circuits, operating as room temperature ballistic electronic devices.


title:
Low field extension for magnetometers (TinyBee) used for investigations
  on low-dimensional superconductors with Bc1 < 5G

abstract:
  In this article a simple and easy to install low magnetic field extension of
the SQUID magnetometer Quantum Design MPMS-7 is described. This has been
accomplished by complementing the MPMS-7 magnet control system with a
laboratory current supply for the low magnetic field region (B \leq 200G). This
hard- and software upgrade provides a significant gain in the magnetic field
accuracy up to an order of magnitude compared with the standard instrument's
setup and is improving the resolution to better than 0.01G below 40G. The field
control has been integrated into the Quantum Design MultiVu software for a
transparent and user-friendly operation of this extension. The improvements
achieved are especially useful, when low magnetic field strengths (B < 1G) are
required at high precision. The specific advantages of this application are
illustrated by sophisticated magnetic characterisation of lowdimensional
superconductors like Sc3CoC4 and SnSe2{Co({\eta}-C5H5)2}x.


title:
Flattening of Galaxies of Different Morphological Types in Subclusters
  of Coma

abstract:
  The dependence of flattening of galaxies on the density of galaxies in
subclusters selected around galaxies NGC4889, NGC4874 and NGC4839 in the Coma
cluster has been studied. The mean values of observed ratios of galaxy
diameters and histograms of their distributions indicate that in the central,
dense regions of subclusters E and S0 type galaxies are close to spheroidals.
Spiral galaxies in subcllusters are found with a hydrogen deficit that about 5
times exceeds the hydrogen deficit in spirals within the halo of the Coma
cluster. Most of spirals with a hydrogen deficit in the subcluster around NGC
4874 according to their 3-D coordinates are located closer to the south-east
edge of this subcluster near an extended gas filament in the x-ray region. This
may indicate over the move of this subcluster toward the central condensation
of faint galaxies in the Coma cluster for a possible merge with it.


title: Explicit solutions of division problems for matrices of polynomials

abstract:
  We present integral representations of solutions to division problems
involving matrices of polynomials in several complex variables. We also find
estimates of the polynomial degree of the solutions by means of careful degree
estimates of the so-called Hefer forms which are components of the
representations.


title: XPOL - the correlation polarimeter at the IRAM 30m telescope

abstract:
  XPOL, the first correlation polarimeter at a large millimeter telescope, uses
a flexible digital correlator to measure all four Stokes parameters
simultaneously, i.e. the total power I, the linear polarization components Q
and U, and the circular polarization V. The versatility of the backend provides
adequate bandwidth for efficient continuum observations as well as sufficient
spectral resolution (40 kHz) for observations of narrow lines. We demonstrate
that the polarimetry specific calibrations are handled with sufficient
precision, in particular the relative phase between the Observatory's two
orthogonally linearly polarized receivers. The many facets of instrumental
polarization are studied at 3mm wavelength in all Stokes parameters: on-axis
with point sources and off-axis with beam maps. Stokes Q which is measured as
the power difference between the receivers is affected by instrumental
polarization at the 1.5% level. Stokes U and V which are measured as cross
correlations are very little affected (maximum sidelobes 0.6% (U) and 0.3%
(V)). These levels critically depend on the precision of the receiver
alignment. They reach these minimum levels set by small ellipticities of the
feed horns when alignment is optimum (<~ 0.3"). A second critical prerequisite
for low polarization sidelobes turned out to be the correct orientation of the
polarization splitter grid. Its cross polarization properties are modeled in
detail. XPOL observations are therefore limited only by receiver noise in
Stokes U and V even for extended sources. Systematic effects set in at the 1.5%
level in observations of Stokes Q. With proper precautions, this limitation can
be overcome for point sources. Stokes Q observations of extended sources are
the most difficult with XPOL.


title: Mean value one of prime-pair constants

abstract:
  For k greater than 1 and r different from 0, let pi^k_{2r}(x) denote the
number of prime pairs (p,p^k+2r) with p not exceeding (large) x. By the
Bateman-Horn conjecture, the function pi^k_{2r}(x) should be asymptotic to
(2/k)C^k_{2r}li_2(x), with certain specific constants C^k_{2r}. Heuristic
arguments lead to the conjecture that these constants have mean value one, just
like the Hardy-Littlewood constants C_{2r} for prime pairs (p,p+2r). The
conjecture is supported by extensive numerical work.


title:
Hall effect and magnetoresistance in single crystals of
  NdFeAsO$_{1-x}$F$_{x}$

abstract:
  Hall effect and magnetoresistance have been measured on single crystals of
$NdFeAsO_{1-x}F_{x}$ with x = 0 ($T_c$ = 0 $ $K) and x = 0.18 ($T_c$ = 50 $
$K). For the undoped samples, strong Hall effect and magnetoresistance with
strong temperature dependence were found below about 150 K. The
magnetoresistance was found to be as large as 30% at 15 K at a magnetic field
of 9 T. From the transport data we found that the transition near 155 K was
accomplished in two steps: first one occurs at 155 K which may be associated
with the structural transition, the second one takes place at about 140 K which
may correspond to the spin-density wave like transition. In the superconducting
sample with $T_c$ = 50 $ $K, it is found that the Hall coefficient also reveals
a strong temperature dependence with a negative sign. But the magnetoresistance
becomes very weak and does not satisfy the Kohler's scaling law. These
dilemmatic results (strong Hall effect and very weak magnetoresistance) prevent
to understand the normal state electric conduction by a simple multi-band model
by taking account the electron and hole pockets. Detailed analysis further
indicates that the strong temperature dependence of $R_H$ cannot be easily
understood with the simple multi-band model either. A picture concerning a
suppression to the density of states at the Fermi energy in lowering
temperature is more reasonable. A comparison between the Hall coefficient of
the undoped sample and the superconducting sample suggests that the doping may
remove the nesting condition for the formation of the SDW order, since both
samples have very similar temperature dependence above 175 K.


title: Spontaneous CP-violation in the strong interaction at theta = pi

abstract:
  Spontaneous CP-violation in the strong interaction is analyzed at theta = pi
within the framework of the two-flavor NJL model. It is found that the
occurrence of spontaneous CP-violation at theta = pi depends on the strength of
the 't Hooft determinant interaction, which describes the effect of instanton
interactions. The dependence of the phase structure, and in particular of the
CP-violating phase, on the quark masses, temperature, baryon and isospin
chemical potential is examined in detail. When available a comparison to
earlier results from chiral perturbation theory is made. From our results we
conclude that spontaneous CP-violation in the strong interaction is an
inherently low-energy phenomenon. In all cases we find agreement with the
Vafa-Witten theorem, also at nonzero density and temperature. Meson masses and
mixing in the CP-violating phase display some unusual features as a function of
instanton interaction strength. A modification of the condition for charged
pion condensation at nonzero isospin chemical potential and a novel phase of
charged a_0 mesons are discussed.


title: The Arecibo Legacy Fast ALFA (ALFALFA) Extragalactic HI Survey

abstract:
  The Arecibo Legacy Fast ALFA (ALFALFA) survey is a program aimed at obtaining
a census of HI-bearing objects over a cosmologically significant volume of the
local universe. When complete in ~3-4 years, it will cover 7000 square degrees
of high latitude sky using the 305m telescope and the seven-beam Arecibo L-band
feed array (ALFA). As of May 1, 2008, almost 60% of the required observations
are complete and a catalog exists in preliminary form for 25% of the final sky
area. ALFALFA is detecting about twice as many HI sources as predicted based on
previously published HI mass functions and should deliver a final catalog of
>25000 extragalactic HI sources. ALFALFA will detect hundreds of galaxies with
HI masses less than 10**7.5 solar masses and similarly large numbers greater
than 10**10.3 Msun. Its centroiding accuracy allows for the immediate
identification of highly probably optical counterparts to each HI detection.
Fewer than 3% of all extragalactic HI sources, and < 1% of ones with HI masses
> 10**9.5 Msun cannot be identified with a stellar counterpart. The hundreds of
HI sources with observed line widths of 20-30 km/s include a population of
optically faint dwarf galaxies. The objects with highest HI masses exhibit a
range of morphologies, optical colors and surface brightnesses, but most appear
to be massive disk systems. The latter represent the population likely to
dominate future studies of HI at high redshift.


title: Experimental quantum key distribution with an untrusted source

abstract:
  The photon statistics of a quantum key distribution (QKD) source is crucial
for security analysis. In this paper, we propose a practical method, with only
a beam splitter and photodetector involved, to monitor the photon statistics of
a QKD source. By implementing in a Plug&Play QKD system, we show that the
method is highly practical. The final secure key rate is 52 bit/s, comparing to
78 bit/s when the source is treated as a trusted source.


title:
Possible two-gap superconductivity in NdFeAs(O,F) probed by
  point-contact Andreev-reflection spectroscopy

abstract:
  Systematic studies of the NdFeAsOF superconducting energy gap via the
point-contact Andreev-reflection (PCAR) spectroscopy are presented. The PCAR
conductance spectra show at low temperatures a pair of gap-like peaks at about
4 - 7 mV indicating the superconducting energy gap and in most cases also a
pair of humps at around 10 mV. Fits to the s-wave two-gap model of the PCAR
conductance allowed to determine two superconducting energy gaps in the system.
The energy-gap features however disappear already at T* = 15 to 20 K, much
below the particular Tc of the junction under study. At T* a zero-bias
conductance (ZBC) peak emerges, which at higher temperatures usually overwhelms
the spectrum with intensity significantly higher than the conductance signal at
lower temperatures. Possible causes of this unexpected temperature effect are
discussed. In some cases the conductance spectra show just a reduced
conductance around the zero-bias voltage, the effect persisting well above the
bulk transition temperature. This indicates a presence of the pseudogap in the
system.


title: Conference Summary: HI Science in the Next Decade

abstract:
  The atomic hydrogen (HI) 21cm line measures the gas content within and around
galaxies, traces the dark matter potential and probes volumes and objects that
other surveys do not. Over the next decade, 21cm line science will exploit new
technologies, especially focal plane and aperture arrays, and will see the
deployment of Epoch of Reionization/Dark Age detection experiments and Square
Kilometer Array (SKA) precursor instruments. Several experiments designed to
detect and eventually to characterize the reionization history of the
intergalactic medium should deliver first results within two-three years time.
Although "precision cosmology" surveys of HI in galaxies at z ~ 1 to 3 require
the full collecting area of the SKA, a coherent program of HI line science
making use of the unique capabilities of both the existing facilities and the
novel ones demonstrated by the SKA precursors will teach us how many gas rich
galaxies there really are and where they reside and will yield fundamental
insight into how galaxies accrete gas, form stars and interact with their
environment.


title: A Dirac Sea of Quantized Superluminal States in the Kerr-Newman Disk

abstract:
  We model the continuous material component of the Kerr-Newman disk as a
discrete distribution of superluminal particles undergoing quantized orbital
rotation with velocity $v/c = a/r$. By matching the discrete distribution in
the continuous limit with the Kerr disk densities, we derive the quantized
energy and momentum states of the superluminal orbits. We conclude that the
Kerr-Newman disk may be modeled as a Dirac sea of these superluminal states and
we identify possible excited states of the disk.


title: Superconductivity above 50 K in Tb$_{1-x}$Th$_{x}$FeAsO

abstract:
  We have successfully synthesized one member of LnFeAsO (Ln stands for
lanthanides) with Ln=Tb. By partial substitution of Tb$^{3+}$ by Th$^{4+}$,
superconductivity with onset $T_{c}$ up to 52 K was observed. In the undoped
parent compound, the magnetic moments of Tb$^{3+}$ ions order
antiferromagnetically (AFM) at $T_N$ of 2.5 K, and there exists an anomaly in
the resistivity at $T^*$ of about 124 K which corresponds to the structural
phase transition and/or AFM ordering of magnetic moments of Fe$^{2+}$ ions.
This anomaly is severely suppressed by Th doping, similar to the cases of F
doped LnFeAsO series. Thermopower measurements show that the charge carrier is
electron-like for both undoped and Th doped compounds, and enhanced thermopower
in Th doped samples was observed.


title:
Negative refraction in active and passive media: a discussion of various
  criteria

abstract:
  There are three widely-used conditions for characterizing negative refraction
in isotropic dielectric-magnetic materials. Here we demonstrate that whilst all
the different conditions are equivalent for purely passive media, they are
distinct if active media are considered. Further, these criteria can also be
applied to negative refraction in acoustic materials, where we might replace
the dielectric permittivity $\epsilon$ with a bulk modulus $\kappa$, and the
magnetic permeability $\mu$ with the mass density $\rho$.


title: Horizon surface gravity as 2d geodesic expansion

abstract:
  The surface gravity of any Killing horizon, in any spacetime dimension, can
be interpreted as a local, two-dimensional expansion rate seen by freely
falling observers when they cross the horizon. Any two-dimensional congruence
of geodesics invariant under the Killing flow can be used to define this
expansion, provided that the observers have unit Killing energy.


title: On the resonance eigenstates of an open quantum baker map

abstract:
  We study the resonance eigenstates of a particular quantization of the open
baker map. For any admissible value of Planck's constant, the corresponding
quantum map is a subunitary matrix, and the nonzero component of its spectrum
is contained inside an annulus in the complex plane, $|z_{min}|\leq |z|\leq
|z_{max}|$. We consider semiclassical sequences of eigenstates, such that the
moduli of their eigenvalues converge to a fixed radius $r$. We prove that, if
the moduli converge to $r=|z_{max}|$, then the sequence of eigenstates
converges to a fixed phase space measure $\rho_{max}$. The same holds for
sequences with eigenvalue moduli converging to $|z_{min}|$, with a different
limit measure $\rho_{min}$. Both these limiting measures are supported on
fractal sets, which are trapped sets of the classical dynamics. For a general
radius $|z_{min}|< r < |z_{max}|$, we identify families of eigenstates with
precise self-similar properties.


title: Is Teleportation a (quantum) mystery?

abstract:
  Since its discovery quantum teleportation has often been seen as a
manifestation, indeed the epitome, of the very paradoxical and mysterious
nature of quantum theory itself. It is commonly regarded as genuinely quantum
and essentially paradoxical. Although a common approach to teleportation
amongst physicists nowadays is a somewhat operational one, some researchers are
making an effort to deflate the above views.
  On the one hand, it was recently argued that the paradox of information
transfer taking place in teleportation is dissolved (Timpson, 2006) by
appealing the very notion of information. On the other hand, it was
demonstrated that some classical versions of teleportation retain its important
features, which hitherto were considered genuinely quantum (Cohen, 2003;
Collins&Popescu, 2002; Hardy, 1999; Mor, 2006; Spekkens, 2007).
  I will present a special version of a quantum teleportation protocol which is
in a sense split into classical and quantum steps. This description provides us
with a unified picture of teleportation in both domains. It will be explicitly
shown how classical teleportation is embedded in the quantum protocol.
Moreover, the classical step can be successfully accomplished even if the state
shared by the parties is completely disentangled [this is consistent with the
result obtained in (Wang, 2005)]. Yet, all the (apparent) paradoxical features
usually associated with quantum teleportation are clearly present in this step.
In particular, this demonstrates that entanglement cannot be ultimately
responsible and not necessary for the (paradoxical?) information transfer.
  Thus, even if one considers teleportation as mysterious, all its mysteries
are shifted from quantum domain into purely classical one.


title: Inelastic Scattering from Local Vibrational Modes

abstract:
  We study a nonuniversal contribution to the dephasing rate of conduction
electrons due to local vibrational modes. The inelastic scattering rate is
strongly influenced by multiphonon excitations, exhibiting oscillatory
behaviour. For higher frequencies, it saturates to a finite, coupling dependent
value. In the strong coupling limit, the phonon is almost completely softened,
and the inelastic cross section reaches its maximal value. This represents a
magnetic field insensitive contribution to the dephasing time in mesoscopic
systems, in addition to magnetic impurities.


title: Supermanifolds from Feynman graphs

abstract:
  We generalize the computation of Feynman integrals of log divergent graphs in
terms of the Kirchhoff polynomial to the case of graphs with both fermionic and
bosonic edges, to which we assign a set of ordinary and Grassmann variables.
This procedure gives a computation of the Feynman integrals in terms of a
period on a supermanifold, for graphs admitting a basis of the first homology
satisfying a condition generalizing the log divergence in this context. The
analog in this setting of the graph hypersurfaces is a graph supermanifold
given by the divisor of zeros and poles of the Berezinian of a matrix
associated to the graph, inside a superprojective space. We introduce a
Grothendieck group for supermanifolds and we identify the subgroup generated by
the graph supermanifolds. This can be seen as a general procedure to construct
interesting classes of supermanifolds with associated periods.


title:
Unusual electron correlations in NaxCoO2 due to the spin-state
  quasidegeneracy of cobalt ions

abstract:
  Recent studies exposed many remarkable properties of layered cobaltates
NaxCoO2. Surprisingly, many-body effects have been found to increase at
sodium-rich compositions of NaxCoO2 where one expects a simple, nearly free
motion of the dilute S=1/2 holes doped into a band insulator NaCoO2. Here we
discuss the origin of enigmatic correlations that turn a doped NaCoO2 into a
strongly correlated electronic system. A minimal model including orbital
degeneracy is proposed and its predictions are discussed. The model is based on
a key property of cobalt oxides - the spin-state quasidegeneracy of CoO6
octahedral complex - which has been known, e.g., in the context of an unusual
physics of LaCoO3 compound. Another important ingredient of the model is the
90-degree Co-O-Co bonding in NaxCoO2 which allows nearest-neighbor $t_{2g}-e_g$
hopping. This hopping introduces a dynamical mixture of electronic
configurations $t_{2g}^6, S=0$ and $t_{2g}^5e_g^1, S=1$ of neighboring cobalt
ions. We show that scattering of charge carriers on spin-state fluctuations
suppresses their coherent motion and leads to the spin-polaron physics at
$x\sim 1$. At larger doping when coherent fermionic bands are formed, the model
predicts singlet superconductivity of extended s-wave symmetry. The presence of
low-lying spin states of Co$^{3+}$ is essential for the pairing mechanism.
Implications of the model for magnetic orderings are also discussed.


title: From primordial $^4$He abundance to the Higgs field

abstract:
  We constrain the possible time variation of the Higgs vacuum expectation
value ($v$) by recent results on the primordial $^4$He abundance ($Y_P$). For
that, we improve the analytic models of the key-processes in our previous
analytic calculation of the primordial $^4$He abundance. Furthermore, the
latest results on the neutron decay, the baryon to photon ratio based on 5-year
WMAP observations and a new dependence of the deuteron binding energy on $v$
are incorporated.
  Finally, we approximate the weak freeze-out, the cross section of
photo-disintegration of the deuteron, the mean lifetime of the free neutron,
the mass difference of neutron and proton, the Fermi coupling constant, the
mass of the electron and the binding energy of the deuteron by terms of $v$, to
constrain its possible time variation by recent results on the primordial
$^4$He abundance: $|\frac{\Delta v}{v}| ~ \leq 1.5 \cdot 10^{-4}$.


title: f-Sum Rule and Unconventional Spectral Weight Transfer in Graphene

abstract:
  We derive and analyze the f-sum rule for a two-dimensional (2D) system of
interacting electrons whose behavior is described by the Dirac equation. We
apply the sum rule to analyze the spectral weight transfer in graphene within
different approximations discussed in the literature. We find that the sum rule
is generically dominated by inter-band transitions while other excitations
produce sub-leading behavior. The f-sum rule provides strong constraints for
theories of interacting electrons in graphene.


title: Activity-dependent stochastic resonance in recurrent neuronal networks

abstract:
  We use a biophysical model of a local neuronal circuit to study the
implications of synaptic plasticity for the detection of weak sensory stimuli.
Networks with fast plastic coupling show behavior consistent with stochastic
resonance. Addition of an additional slow coupling that accounts for the
asynchronous release of neurotransmitter results in qualitatively different
properties of signal detection, and also leads to the appearance of transient
post-stimulus bistability. Our results suggest testable hypothesis with regard
to the self-organization and dynamics of local neuronal circuits.


title:
Dynamical response to supernova-induced gas removal in spiral galaxies
  with dark matter halo

abstract:
  We investigate the dynamical response, in terms of disc size and rotation
velocity, to mass loss by supernovae in the evolution of spiral galaxies. A
thin baryonic disc having the Kuzmin density profile embedded in a spherical
dark matter halo having a density profile proposed by Navarro, Frenk & White is
considered. For a purpose of comparison, we also consider the homogeneous and
$r^{-1}$ profiles for dark matter in a truncated spherical halo. Assuming for
simplicity that the dark matter distribution is not affected by mass loss from
discs and the change of baryonic disc matter distribution is homologous, we
evaluate the effects of dynamical response in the resulting discs. We found
that the dynamical response only for an adiabatic approximation of mass loss
can simultaneously account for the rotation velocity and disc size as observed
particularly in dwarf spiral galaxies, thus reproducing the Tully-Fisher
relation and the size versus magnitude relation over the full range of
magnitude. Furthermore, we found that the mean specific angular momentum in
discs after the mass loss becomes larger than that before the mass loss,
suggesting that the mass loss would occur most likely from the central disc
region where the specific angular momentum is low.


title: Superconductivity induced by oxygen deficiency in Sr-doped LaOFeAs

abstract:
  We synthesized Sr-doped $La_{0.85}Sr_{0.15}OFeAs$ sample with single phase,
and systematically studied the effect of oxygen deficiency in the Sr-doped
LaOFeAs system. It is found that substitution of Sr for La indeed induces the
hole carrier evidenced by positive thermoelectric power (TEP), but no bulk
superconductivity is observed. The superconductivity can be realized by
annealing the as-grown sample in vacuum to produce the oxygen deficiency. With
increasing the oxygen deficiency, the superconducting transition temperature
($T_c$) increases and maximum $T_c$ reaches about 26 K the same as that in
La(O,F)FeAs. TEP dramatically changes from positive to negative in the
nonsuperconducting as-grown sample to the superconducting samples with oxygen
deficiency. While $R_H$ is always negative for all samples (even for Sr-doped
as grown sample). It suggests that the $La_{0.85}Sr_{0.15}O_{1-\delta}FeAs$ is
still electron-type superconductor.


title: Anyons from fermions with conventional two-body interactions

abstract:
  Emergent anyons are the key elements of the topological quantum computation
and topological quantum memory. We study a two-component fermion model with
conventional two-body interaction in an open boundary condition and show that
several subsets in the low-lying excitations obey the same fusion rules as
those of the toric code model. Those string-like non-local excitations in a
given subset obey mutual semionic statistics. We show how to peel off one of
such subset from other degenerate subsets and manipulate anyons in cold dipolar
Fermi atoms or cold dipolar fermionic heteronuclear molecules in optical
lattices by means of the established techniques.


title:
Formation and accretion history of terrestrial planets from runaway
  growth through to late time: implications for orbital eccentricity

abstract:
  Remnant planetesimals might have played an important role in reducing the
orbital eccentricities of the terrestrial planets after their formation via
giant impacts. However, the population and the size distribution of remnant
planetesimals during and after the giant impact stage are unknown, because
simulations of planetary accretion in the runaway growth and giant impact
stages have been conducted independently. Here we report results of direct
N-body simulations of the formation of terrestrial planets beginning with a
compact planetesimal disk. The initial planetesimal disk has a total mass and
angular momentum as observed for the terrestrial planets, and we vary the width
(0.3 and 0.5AU) and the number of planetesimals (1000-5000). This initial
configuration generally gives rise to three final planets of similar size, and
sometimes a fourth small planet forms near the location of Mars. Since a
sufficient number of planetesimals remains, even after the giant impact phase,
the final orbital eccentricities are as small as those of the Earth and Venus.


title: A direct road to Majorana fields

abstract:
  A concise discussion of spin-1/2 field equations with a special focus on
Majorana spinors is presented. The Majorana formalism which describes massive
neutral fermions by the help of two-component or four-component spinors is of
fundamental importance for the understanding of mathematical aspects of
supersymmetric and other extensions of the Standard Model of particle physics,
which may play an increasingly important role at the beginning of the LHC era.
The interplay between the two-component and the four-component formalism is
highlighted in an introductory way. Majorana particles are predicted both by
grand unified theories, in which these particles are neutrinos, and by
supersymmetric theories, in which they are photinos, gluinos and other states.


title: Stimulated scattering and lasing of intersubband cavity polaritons

abstract:
  We present a microscopic theory describing the stimulated scattering of
intersubband polariton excitations in a microcavity-embedded two-dimensional
electron gas. In particular, we consider the polariton scattering induced by
the spontaneous emission of optical phonons. Our theory demonstrates the
possibility of final-state stimulation for the scattering of such composite
excitations, accounting for the deviations from perfect bosonicity occurring at
high excitation densities. By using realistic parameters for a GaAs
semiconductor system, we predict how to achieve a quantum degenerate regime,
leading to ultralow threshold lasing without population inversion.


title: Group actions and Helly's theorem

abstract:
  We describe a connection between the combinatorics of generators for certain
groups and the combinatorics of Helly's 1913 theorem on convex sets. We use
this connection to prove fixed point theorems for actions of these groups on
nonpositively curved metric spaces. These results are encode d in a property
that we introduce called ``property $\FA_r$'', which reduces to Serre's
property $\FA$ when $r=1$. The method applies to $S$-arithmetic groups in
higher $\Q$-rank, to simplex reflection groups (including some non-arithmetic
ones), and to higher rank Chevalley groups over polynomial and other rings (for
example $\SL_n(\Z[x_1,..., x_d]), n>2$).


title: Macroscopically-Discrete Quantum Cosmology

abstract:
  To Milne's Lorentz-group-based spacetime and Gelfand-Naimark unitary
representations of this group we associate a Fock space of 'cosmological
preons'-quantum-theoretic universe constituents. Milne's 'cosmological
principle' relies on Lorentz invariance of 'age'--global time. We divide
Milne's spacetime into 'slices' of fixed macroscopic width in age, with
'cosmological rays' defined on (hyperbolic) slice boundaries-Fock space
attaching only to these exceptional universe ages. Each (fixed-age) preon
locates within a 6-dimensional manifold, one of whose 3 'extra' dimensions
associates in Dirac sense to a self-adjoint operator that represents preon
(continuous) local time, the operator canonically-conjugate thereto
representing preon (total) energy. Self-adjoint-operator expectations at any
spacetime-slice boundary prescribe throughout the following slice a
non-fluctuating 'mundane reality'- electromagnetic and gravitational potentials
'tethered' to current densities of locally-conserved electric charge and
energy-momentum. The ray at the upper boundary of a slice is determined from
the lower-boundary ray by branched slice-traversing Feynman paths that carry
(divergence-free) potential-depending action. A macroscopically-stable
positive-energy single-preon wave function identifies either with a
Standard-Model elementary particle or with a graviton. Within
intermediate-density universe regions such as the solar system, where
reproducible measurement is meaningful, special relativity--Poincar\'e
invariance-is accurate for spacetime scales far below that of Hubble and far
above that of Planck.


title: Transcendence of the Gaussian Liouville number and relatives

abstract:
  {\em The Liouville number}, denoted $l$, is defined by
$$l:=0.100101011101101111100...,$$ where the $n$th bit is given by
${1/2}(1+\gl(n))$; here $\gl$ is the Liouville function for the parity of prime
divisors of $n$. Presumably the Liouville number is transcendental, though at
present, a proof is unattainable. Similarly, define {\em the Gaussian Liouville
number} by $$\gamma:=0.110110011100100111011...$$ where the $n$th bit reflects
the parity of the number of rational Gaussian primes dividing $n$, 1 for even
and 0 for odd.
  In this paper, we prove that the Gaussian Liouville number and its relatives
are transcendental. One such relative is the number
$$\sum_{k=0}^\infty\frac{2^{3^k}}{2^{3^k2}+2^{3^k}+1}=0.101100101101100100101...,$$
where the $n$th bit is determined by the parity of the number of prime divisors
that are equivalent to 2 modulo 3.
  We use methods similar to that of Dekking's proof of the transcendence of the
Thue--Morse number \cite{Dek1} as well as a theorem of Mahler's \cite{Mahl1}.
(For completeness we provide proofs of all needed results.) This method
involves proving the transcendence of formal power series arising as generating
functions of completely multiplicative functions.


title:
Fully integrated transport approach to heavy ion reactions with an
  intermediate hydrodynamic stage

abstract:
  We present a coupled Boltzmann and hydrodynamics approach to relativistic
heavy ion reactions. This hybrid approach is based on the Ultra-relativistic
Quantum Molecular Dynamics (UrQMD) transport approach with an intermediate
hydrodynamical evolution for the hot and dense stage of the collision.
Event-by-event fluctuations are directly taken into account via the
non-equilibrium initial conditions generated by the initial collisions and
string fragmentations in the microscopic UrQMD model. After a (3+1)-dimensional
ideal hydrodynamic evolution, the hydrodynamical fields are mapped to hadrons
via the Cooper-Frye equation and the subsequent hadronic cascade calculation
within UrQMD proceeds to incorporate the important final state effects for a
realistic freeze-out. This implementation allows to compare pure microscopic
transport calculations with hydrodynamic calculations using exactly the same
initial conditions and freeze-out procedure. The effects of the change in the
underlying dynamics - ideal fluid dynamics vs. non-equilibrium transport theory
- will be explored. The freeze-out and initial state parameter dependences are
investigated for different observables. Furthermore, the time evolution of the
baryon density and particle yields are discussed. We find that the final pion
and proton multiplicities are lower in the hybrid model calculation due to the
isentropic hydrodynamic expansion while the yields for strange particles are
enhanced due to the local equilibrium in the hydrodynamic evolution. The
results of the different calculations for the mean transverse mass excitation
function, rapidity and transverse mass spectra for different particle species
at three different beam energies are discussed in the context of the available
data.


title:
Quantum corrections of the Dzyaloshinskii-Moriya interaction on the
  spin-1/2 AF-Heisenberg chain in an uniform magnetic field

abstract:
  We have investigated the ground state phase diagram of the 1D AF spin-1/2
Heisenberg model with the staggered Dzyaloshinskii-Moriya (DM) interaction in
an external uniform magnetic field $H$. We have used the exact diagonalization
technique. In the absence of the uniform magnetic field (H=0), we have shown
that the DM interaction induces a staggered chiral phase. The staggered chiral
phase remains stable even in the presence of the uniform magnetic field. We
have identified that the ground state phase diagram consists of four Luttinger
liquid, staggered chiral, spin-flop, and ferromagnetic phases.


title: Diffraction of fast atoms and molecules from surfaces

abstract:
  Prompted by recent experimental developments, a theory of surface scattering
of fast atoms at grazing incidence is developed. The theory gives rise to a
quantum mechanical limit for ordered surfaces that describes coherent
diffraction peaks whose thermal attenuation is governed by a Debye-Waller
factor, however, this Debye-Waller factor has values much larger than would be
calculated using simple models. A classical limit for incoherent scattering is
obtained for high energies and temperatures. Between these limiting classical
and quantum cases is another regime in which diffraction features appear that
are broadened by the motion in the fast direction of the scattered beam but
whose intensity is not governed by a Debye-Waller factor. All of these limits
appear to be accessible within the range of currently available experimental
conditions.


title:
Conservation laws and hierarchies of potential symmetries for certain
  diffusion equations

abstract:
  We show that the so-called hidden potential symmetries considered in a recent
paper [Gandarias M., Physica A, 2008, V.387, 2234-2242] are ordinary potential
symmetries that can be obtained using the method introduced by Bluman and
collaborators. In fact, these are simplest potential symmetries associated with
potential systems which are constructed with single conservation laws having no
constant characteristics. Furthermore we classify the conservation laws for
classes of porous medium equations and then using the corresponding conserved
(potential) systems we search for potential symmetries. This is the approach
one needs to adopt in order to determine the complete list of potential
symmetries. The provenance of potential symmetries is explained for the porous
medium equations by using potential equivalence transformations. Point and
potential equivalence transformations are also applied to deriving new results
on potential symmetries and corresponding invariant solutions from known ones.
In particular, in this way the potential systems, potential conservation laws
and potential symmetries of linearizable equations from the classes of
differential equations under consideration are exhaustively described. Infinite
series of infinite-dimensional algebras of potential symmetries are constructed
for such equations.


title:
Measurement of b-jet Shapes in Inclusive Jet Production in p pbar
  Collisions at sqrt{s} = 1.96 TeV

abstract:
  We present a measurement of the shapes of b-jets using 300 pb-1 of data
obtained with the upgraded Collider Detector at Fermilab (CDF II) in p pbar
collisions at center of mass energy sqrt{s}=1.96 TeV. This measurement covers a
wide transverse momentum range, from 52 to 300 GeV/c. Samples of heavy-flavor
enhanced jets together with inclusive jets are used to extract the average
shapes of b-jets. The b-jets are expected to be broader than inclusive jets.
Moreover, b-jets containing a single b-quark are expected to be narrower than
those containing a b bbar pair from gluon splitting. The measured b-jet shapes
are found to be significantly broader than expected from the PYTHIA and HERWIG
Monte Carlo simulations. This effect may arise from an underestimation of the
fraction of b-jets originating from gluon splitting in these simulations.


title:
Relativistic simulations of the phase-transition-induced collapse of
  neutron stars

abstract:
  An increase in the central density of a neutron star may trigger a phase
transition from hadronic matter to deconfined quark matter in the core, causing
it to collapse to a more compact hybrid-star configuration. We present a study
of this, building on previous work by Lin et al. (2006). We follow them in
considering a supersonic phase transition and using a simplified equation of
state, but our calculations are general relativistic (using 2D simulations in
the conformally flat approximation) as compared with their 3D Newtonian
treatment. We also improved the treatment of the initial phase transformation,
avoiding the introduction of artificial convection. As before, we find that the
emitted gravitational-wave spectrum is dominated by the fundamental
quasi-radial and quadrupolar pulsation modes but the strain amplitudes are much
smaller than suggested previously, which is disappointing for the detection
prospects. However, we see significantly smaller damping and observe a
nonlinear mode resonance which substantially enhances the emission in some
cases. We explain the damping mechanisms operating, giving a different view
from the previous work. Finally, we discuss the detectability of the
gravitational waves, showing that the signal-to-noise ratio for current or
second generation interferometers could be high enough to detect such events in
our Galaxy, although third generation detectors would be needed to observe them
out to the Virgo cluster, which would be necessary for having a reasonable
event rate.


title: Observational evidence for return currents in solar flare loops

abstract:
  Context: The common flare scenario comprises an acceleration site in the
corona and particle transport to the chromosphere. Using satellites available
to date it has become possible to distinguish between the two processes of
acceleration and transport, and study the particle propagation in flare loops
in detail, as well as complete comparisons with theoretical predictions.
  Aims: We complete a quantitative comparison between flare hard X-ray spectra
observed by RHESSI and theoretical predictions. This enables acceleration to be
distinguished from transport and the nature of transport effects to be
explored.
  Methods: Data acquired by the RHESSI satellite were analyzed using full sun
spectroscopy as well as imaging spectroscopy methods. Coronal source and
footpoint spectra of well observed limb events were analyzed and quantitatively
compared to theoretical predictions. New concepts are introduced to existing
models to resolve discrepancies between observations and predictions.
  Results: The standard thin-thick target solar flare model cannot explain the
observations of all events. In the events presented here, propagation effects
in the form of non-collisional energy loss are of importance to explain the
observations. We demonstrate that those energy losses can be interpreted in
terms of an electric field in the flare loop. One event seems consistent with
particle propagation or acceleration in lower than average density in the
coronal source.
  Conclusions: We find observational evidence for an electric field in flare
loops caused by return currents.


title: Gauss-Manin connection and t-adic geometry

abstract:
  We show that the de Rham cohomology of any separated and smooth rigid variety
over a field of Laurent series of characteristic zero carries a natural formal
meromorphic connection, which we call the Gauss-Manin connection. We compare it
with the Gauss-Manin connection of a proper and smooth variety over a curve,
and with the Gauss-Manin connection of the Milnor fibration at an isolated
complex hypersurface singularity.


title: On the connection between the Nekhoroshev theorem and Arnold Diffusion

abstract:
  The analytical techniques of the Nekhoroshev theorem are used to provide
estimates on the coefficient of Arnold diffusion along a particular resonance
in the Hamiltonian model of Froeschl\'{e} et al. (2000). A resonant normal form
is constructed by a computer program and the size of its remainder
$||R_{opt}||$ at the optimal order of normalization is calculated as a function
of the small parameter $\epsilon$. We find that the diffusion coefficient
scales as $D\propto||R_{opt}||^3$, while the size of the optimal remainder
scales as $||R_{opt}|| \propto\exp(1/\epsilon^{0.21})$ in the range
$10^{-4}\leq\epsilon \leq 10^{-2}$. A comparison is made with the numerical
results of Lega et al. (2003) in the same model.


title: Multiplicative Properties of the Slice Filtration

abstract:
  We show that the slice filtration introduced by Voevodsky is compatible in a
suitable sense with the symmetric monoidal structure in the category of motivic
symmetric T-spectra constructed by Jardine. It follows from this compatibility
that the zero slice of the sphere spectrum s_{0}(1) is a ring spectrum and that
for every symmetric T-spectrum X, and every integer n; the n-slice s_{n}(X) is
a module over s_{0}(1). In particular, if the base scheme is a field of
characteristic zero, we have that all the slices s_{n}(X) are big motives in
the sense of Voevodsky. We also get as a corollary that the smash product of
symmetric T-spectra induces pairings in the motivic Atiyah-Hirzebruch spectral
sequence.


title:
Schottky groups cannot act on $\mathbb{P}^{2n}_{\mathbb{C}}$ as
  subgroups of $PSL(2n+1,\Bbb{C})$

abstract:
  In this paper we look at a special type of discrete subgroups of
$PSL_{n+1}(\Bbb{C})$ called Schottky groups. We develop some basic properties
of these groups and their limit set when $n > 1$, and we prove that Schottky
groups only occur in odd dimensions, {\it i.e.}, they cannot be realized as
subgroups of $PSL_{2n+1}(\Bbb{C})$.


title: Heat trace asymptotics with singular weight functions

abstract:
  We study the weighted heat trace asymptotics of an operator of Laplace type
with Dirichlet boundary conditions where the weight function exhibits radial
blowup. We give formulas for the first few terms in the expansion in terms of
geometrical data.


title: High Longevity Microlensing Events and Dark Matter Black Holes

abstract:
  Gravitational microlensing has been employed to identify massive halo objects
by their amplification of distant sources; MACHO searches have studied event
times $2 h \lesssim t_0 \lesssim 2 y$ corresponding masses in the range
$10^{-6} M_{\odot} \lesssim M \lesssim 100 M_{\odot}$. We suggest that larger
masses up to $10^6 M_{\odot}$ are also of considerable interest. It has not
been excluded that there is a significant number of halo black holes with such
high masses as suggested by cosmological entropy considerations and potentially
detectable by high longevity microlensing events.


title:
The Thermodynamic Limit of Quantum Coulomb Systems. Part I. General
  Theory

abstract:
  This article is the first in a series dealing with the thermodynamic
properties of quantum Coulomb systems.
  In this first part, we consider a general real-valued function $E$ defined on
all bounded open sets of $\R^3$. Our aim is to give sufficient conditions such
that $E$ has a thermodynamic limit. This means that the limit
$E(\Omega_n)|\Omega_n|^{-1}$ exists for all `regular enough' sequence
$\Omega_n$ with growing volume, $|\Omega_n|\to\ii$, and is independent of the
considered sequence.
  The sufficient conditions presented in our work all have a clear physical
interpretation. In the next paper, we show that the free energies of many
different quantum Coulomb systems satisfy these assumptions, hence have a
thermodynamic limit.


title:
The Thermodynamic Limit of Quantum Coulomb Systems. Part II.
  Applications

abstract:
  In a previous paper, we have developed a general theory of thermodynamic
limits. We apply it here to three different Coulomb quantum systems, for which
we prove the convergence of the free energy per unit volume.
  The first system is the crystal for which the nuclei are classical particles
arranged periodically in space and only the electrons are quantum particles. We
recover and generalize a previous result of Fefferman. In the second example,
both the nuclei and the electrons are quantum particles, submitted to a
periodic magnetic field. We thereby extend a seminal result of Lieb and
Lebowitz. Finally, in our last example we take again classical nuclei but
optimize their position. To our knowledge such a system was never treated
before.
  The verification of the assumptions introduced in the previous paper uses
several tools which have been introduced before in the study of large quantum
systems. In particular, an electrostatic inequality of Graf and Schenker is one
main ingredient of our new approach.


title:
Image charge screening: a new approach to enhance magnetic ordering
  temperatures

abstract:
  We have tested the concept of image charge screening as a new approach to
enhance magnetic ordering temperatures and superexchange interactions in ultra
thin films. Using a 3 monolayer NiO(100) film grown on Ag(100) and an
identically thin film on MgO(100) as model systems, we observed that the Neel
temperature of the NiO film on the highly polarizable metal substrate is 390 K
while that of the film on the poorly polarizable insulator substrate is below
40 K. This demonstrates that screening by highly polarizable media may point to
a practical way towards designing strongly correlated oxide nanostructures with
greatly improved magnetic properties.