title: Evaluating backreaction with the peak model of structure formation

abstract:
  We evaluate the average expansion rate of a universe which contains a
realistic evolving ensemble of non-linear structures. We use the peak model of
structure formation to obtain the number density of structures, and take the
individual structures to be spherical. The expansion rate increases relative to
the FRW value on a timescale of 10-100 billion years, because the universe
becomes dominated by fast-expanding voids. However, the increase is not rapid
enough to correspond to acceleration. We discuss how to improve our treatment.
We also consider various qualitative issues related to backreaction.


title: A Kohn-Sham system at zero temperature

abstract:
  An one-dimensional Kohn-Sham system for spin particles is considered which
effectively describes semiconductor {nano}structures and which is investigated
at zero temperature. We prove the existence of solutions and derive a priori
estimates. For this purpose we find estimates for eigenvalues of the
Schr\"odinger operator with effective Kohn-Sham potential and obtain
$W^{1,2}$-bounds of the associated particle density operator. Afterwards,
compactness and continuity results allow to apply Schauder's fixed point
theorem. In case of vanishing exchange-correlation potential uniqueness is
shown by monotonicity arguments. Finally, we investigate the behavior of the
system if the temperature approaches zero.


title:
Milli-arcsecond astrophysics with VSI, the VLTI spectro-imager in the
  ELT era

abstract:
  Nowadays, compact sources like surfaces of nearby stars, circumstellar
environments of stars from early stages to the most evolved ones and
surroundings of active galactic nuclei can be investigated at milli-arcsecond
scales only with the VLT in its interferometric mode. We propose a
spectro-imager, named VSI (VLTI spectro-imager), which is capable to probe
these sources both over spatial and spectral scales in the near-infrared
domain. This instrument will provide information complementary to what is
obtained at the same time with ALMA at different wavelengths and the extreme
large telescopes.


title: Contribution of the HMPID detector to the high-pT physics at LHC

abstract:
  The LHC will deliver unexplored energy regimes for proton-proton and
heavy-ion collisions. As shown by the RHIC experiments, particle identification
over a large momentum range is essential to disentangle physics processes,
especially in the intermediate p$_T$ (1 $<p_{T}<5$ GeV/c) region. The novel
design of the High-Momentum Particle Identification Detector (HMPID), based on
large surface CsI photocathodes, is able to identify $\pi^{\pm}$, $K^{\pm}$,
$p$ and $\bar{p}$ in the momentum region where bulk medium properties and hard
scatterings interplay. Furthermore, measurement of resonance particles such as
the $\phi \to K^+K^-$ could provide information on the system evolution. The
HMPID layout and segmentation are optimized to study particle correlations at
high momenta describing the early phase and the dynamical evolution of the
collision. At LHC, the increased hard cross section will significantly be
enhanced compared to RHIC. Jet reconstruction via Deterministic Annealing can
address jet quenching and detailed measurements of jet properties. In this
paper, we present these selected topics from the possible HMPID contributions
to the physics goals of LHC.


title:
Field-induced charge-density-wave transitions in the organic metal
  $\alpha$-(BEDT-TTF)$_2$KHg(SCN)$_4$ under hydrostatic pressure

abstract:
  Successive magnetic-field-induced charge-density-wave transitions in the
molecular conductor $\alpha$-(BEDT-TTF)$_2$KHg(SCN)$_4$ are studied in the
hydrostatic pressure regime, in which the zero field charge-density wave
(CDW)state is completely suppressed. The orbital effect of the magnetic field
is demonstrated to restore the density wave, while the orbital quantization
induces different CDW states in different field intervals. In particular, we
have found that at certain field orientations the hysteretic first order
transitions between field-induced CDW subphases become visible at much higher
temperatures. This observation is very well in line with the existing theories
of field-induced CDW transitions.


title:
The running coupling from the four-gluon vertex in Landau gauge
  Yang-Mills theory

abstract:
  We consider the running coupling from the four-gluon vertex in Landau gauge,
SU($N_c$) Yang-Mills theory as given by a combination of dressing functions of
the vertex and the gluon propagator. We determine these functions numerically
from a coupled set of Dyson-Schwinger equations. We reproduce asymptotic
freedom in the ultraviolet momentum region and find a coupling of order one at
mid-momenta. In the infrared we find a nontrivial (i.e. nonzero) fixed point
which is three orders of magnitude smaller than the corresponding fixed point
in the coupling of the ghost-gluon vertex. This result explains why the
Dyson-Schwinger and the functional renormalization group equations for the two
point functions can agree in the infrared, although their structure is quite
different. Our findings also support Zwanziger's notion of an infrared
effective theory driven by the Faddeev-Popov determinant.


title: Microlensing probes the AGN structure of the lensed quasar J1131-1231

abstract:
  We present the analysis of single epoch long slit spectra of the three
brightest images of the gravitationally lensed system J1131-1231. These spectra
provide one of the clearest observational evidence for differential
micro-lensing of broad emission lines (BELs) in a gravitationally lensed
quasar. The micro-lensing effect enables us: (1) to confirm that the width of
the emission lines is anti-correlated to the size of the emitting region; (2)
to show that the bulk of FeII is emitted in the outer parts of the Broad Line
Region (BLR) while another fraction of FeII is produced in a compact region;
(3) to derive interesting informations on the origin of the narrow intrinsic
MgII absorption doublet observed in that system.


title: Spin Accumulation and Spin Relaxation in a Large Open Quantum Dot

abstract:
  We report electronic control and measurement of an imbalance between spin-up
and spin-down electrons in micron-scale open quantum dots. Spin injection and
detection was achieved with quantum point contacts tuned to have spin-selective
transport, with four contacts per dot for realizing a non-local spin-valve
circuit. This provides an interesting system for studies of spintronic effects
since the contacts to reservoirs can be controlled and characterized with high
accuracy. We show how this can be used to extract in a single measurement the
relaxation time for electron spins inside the dot ~ 300 ps and the degree of
spin polarization of the contacts P ~ 0.8.


title:
Labels discover physics: the development of new labelling methods as a
  promising research field for applied physics

abstract:
  Labels and tags are accompanying us in almost each moment of our life and
everywhere we are going, in the form of electronic keys or money, or simply as
labels on products we are buying in shops and markets. The label diffusion,
rapidly increasing for logistic reasons in the actual global market, carries
huge amount of information but it is demanding security and anti-fraud systems.
The first crucial point, for the consumer and producer safety, is to ensure the
authenticity of the labelled products with systems against counterfeiting and
piracy. Recent anti-fraud techniques are based on a sophisticated use of
physical effects, from holograms till magnetic resonance or tunnel transitions
between atomic sublevels. In this paper we will discuss labels and anti-fraud
technologies as a new and very promising research field for applied physics.


title:
Observing the Inverse melting of the vortex lattice in
  Bi$_2$Sr$_2$CaCu$_2$O$_8$ with point defects using Langevin simulations with
  vortex shaking

abstract:
  Langevin dynamics simulations of the vortex matter in the highly-anisotropic
high-temperature superconductor Bi$_2$Sr$_2$CaCu$_2$O$_8$ were performed. We
introduced point defects as a smoothened distribution of a random potential.
Both the electromagnetic and Josephson interactions among pancake vortices were
included. A special shaking and annealing process was introduced to let the
system approach the equilibrium configuration. We are able to see the inverse
melting transition from the Bragg-glass to the amorphous vortex glass state, in
agreement with recent experiments.


title: Space-time Vector Supersymmetry and Massive Spinning Particle

abstract:
  We construct the action of a relativistic spinning particle from a non-linear
realization of a space-time odd vector extension of the Poincar\'e group. For
particular values of the parameters appearing in the lagrangian the model has a
gauge world-line supersymmetry.{As a consequence of this local symmetry there
are BPS solutions in the model preserving 1/5 of the supersymmetries.} A
supersymmetric invariant quantization produces two decoupled 4d Dirac
equations.


title: Implicit regularization beyond one loop order: gauge field theories

abstract:
  We extend a constrained version of Implicit Regularization (CIR) beyond one
loop order for gauge field theories. In this framework, the ultraviolet content
of the model is displayed in terms of momentum loop integrals order by order in
perturbation theory for any Feynman diagram, while the Ward-Slavnov-Taylor
identities are controlled by finite surface terms. To illustrate, we apply CIR
to massless abelian Gauge Field Theories (scalar and spinorial QED) to two loop
order and calculate the two-loop beta-function of the spinorial QED.


title: Exotic (anti)ferromagnetism in single crystals of Pr6Ni2Si3

abstract:
  The ternary intermetallic compound Pr6Ni2Si3, is a member of a structure
series of compounds based on a triangular structure where the number of Pr
atoms in the prism cross section can be systematically varied. Pr6Ni2Si3
contains two distinct Pr lattice sites which result in complex interactions
between the magnetic ions. Extensive measurements of specific heat and
magnetization on single crystal samples indicate that Pr6Ni2Si3 orders with
both a ferromagnet and an antiferromagnet component, with ordering temperatures
of 39.6 K and ~ 32 K, respectively. The ferromagnetic component // c-axis is
accompanied by a large hysteresis, and the antiferromagnetic component,_|_
c-axis is accompanied by a spin-flop-type transition. More detailed
measurements, of the vector magnetization, indicate that the ferromagnetic and
the antiferromagnetic order appear independent of each other. These results not
only clarify the behavior of Pr6Ni2Si3 itself, but also of the other members of
the structure series, Pr5Ni2Si3 and Pr15Ni7Si10.


title:
Modeling magnetohydrodynamics and non equilibrium SoHO/UVCS line
  emission of CME shocks

abstract:
  We provide a guideline to interpret the UVCS emission lines (in particular O
VI and Si XII) during shock wave propagation in the outer solar corona. We use
a numerical MHD model performing a set of simulations of shock waves generated
in the corona and from the result we compute the plasma emission for the O VI
and Si XII including the effects of NEI. We analyze the radiative and spectral
properties of our model with the support of a detailed radiation model
including Doppler dimming and an analytical model for shocks, and, finally, we
synthesize the expected O VI 1032A line profile. We explain several spectral
features of the observations like the absence of discontinuities in the O VI
emission during the shock passage, the brightening of Si XII emission and the
width of the lines. We use our model also to give very simple and general
predictions for the strength of the line wings due to the ions shock heating
and on the line shape for Limb CMEs or Halo CMEs. The emission coming from
post-shock region in the solar corona roughly agrees with the emission from a
simple planar and adiabatic shock, but the effect of thermal conduction and the
magnetic field may be important depending on the event parameters. Doppler
dimming significantly influences the O VI emission while Si XII line brightens
mainly because of the shock compression. Significant shock heating is
responsible for the wide and faint component of the O VI line usually observed
which may be taken as a shock signature in the solar corona.


title:
Scalable continuous-variable entanglement of light beams produced by
  optical parametric oscillators

abstract:
  We show that scalable multipartite entanglement among light fields may be
generated by optical parametric oscillators (OPO). The tripartite entanglement
existent among the three bright beams produced by a single OPO -- pump, signal,
and idler -- is scalable to a system of many OPOs by pumping them in cascade
with the same optical field. This latter serves as an entanglement distributor.
The special case of two OPOs is studied, as it is shown that the resulting five
bright beams share genuine multipartite entanglement. In addition, the
structure of entanglement distribution among the fields can be manipulated to
some degree by tuning the incident pump power. The scalability to many fields
is straightforward, allowing an alternative implementation of a multipartite
quantum information network with continuous variables.


title:
Can We Improve the Preprocessing of Photospheric Vector Magnetograms by
  the Inclusion of Chromospheric Observations?

abstract:
  The solar magnetic field is key to understanding the physical processes in
the solar atmosphere. Nonlinear force-free codes have been shown to be useful
in extrapolating the coronal field upward from underlying vector boundary data.
However, we can only measure the magnetic field vector routinely with high
accuracy in the photosphere, and unfortunately these data do not fulfill the
force-free condition. We must therefore apply some transformations to these
data before nonlinear force-free extrapolation codes can be self-consistently
applied. To this end, we have developed a minimization procedure that yields a
more chromosphere-like field, using the measured photospheric field vectors as
input. The procedure includes force-free consistency integrals, spatial
smoothing, and -- newly included in the version presented here -- an improved
match to the field direction as inferred from fibrils as can be observed in,
e.g., chromospheric H$\alpha$ images. We test the procedure using a model
active-region field that included buoyancy forces at the photospheric level.
The proposed preprocessing method allows us to approximate the chromospheric
vector field to within a few degrees and the free energy in the coronal field
to within one percent.


title:
How bad is to be slow-reacting ? On the effect of the delay in response
  to a changing environment on a population's survival

abstract:
  We consider a simple-model population, whose individuals react with a certain
delay to temporal variations of their habitat. We investigate the impact of
such a delayed-answer on the survival chances of the population, both in a
periodically changing environment, and in the case of an abrupt change of it.
It is found that for population with low degree of mutation-induced
variability, being "slow-reacting" decreases the extinction risk face to
environmental changes. On the contrary, for populations with high mutation
amplitude, the delayed reaction reduces the survival chances.


title:
Comment on "Geoeffectiveness of halo coronal mass ejections" by N.
  Gopalswamy, S. Yashiro, and S. Akiyama

abstract:
  Comment on paper: Gopalswamy, N., S. Yashiro, and S. Akiyama (2007),
Geoeffectiveness of halo coronal mass ejections, J. Geophys. Res., 112, A06112,
doi:10.1029/2006JA012149
  Gopalswamy et al. [2007] studied the geoeffectiveness of halo coronal mass
ejections (CMEs) on the basis of solar observations during 1996-2005 and found
that the geoeffectiveness of 229 frontside halo CMEs was 71%. Recently for
observations of 305 frontside halo CMEs during 1997-2003 the geoeffectiveness
was found to be 40% [Kim et al., 2005]. Complex analysis of both solar and
interplanetary measurements showed that the geoeffectiveness of frontside halo
CMEs is likely to be about 50% [Yermolaev et al., 2005; Yermolaev and
Yermolaev, 2006]. Gopalswamy et al. [2007] did not discuss possible causes of
this difference and were limited only to the general words: "The reason for the
conflicting results (geoeffectiveness of CMEs ranging from 35% to more than
80%) may be attributed to the different definition of halo CMEs and
geoeffectiveness." So, here we shall present our point of view on high
geoeffectivenees of CME obtained in paper by Gopalswamy et al. [2007].


title: Horizons of radiating black holes in Einstein gauss-bonnet gravity

abstract:
  A Vaidya-based model of a radiating black-hole is studied in a 5-dimensional
Einstein gravity with Gauss-Bonnet contribution of quadratic curvature terms.
The structure and locations of the apparent and event horizons of the radiating
black hole are determined.


title: On Factorization Constraints for Branes in the H3+ Model

abstract:
  We comment on the brane solutions for the boundary H3+ model that have been
proposed so far and point out that they should be distinguished according to
the patterns regular/irregular and discrete/continuous. In the literature,
mostly irregular branes have been studied, while results on the regular ones
are rare. For all types of branes, there are questions about how a second
factorization constraint in the form of a b^{-2}/2-shift equation can be
derived. Here, we assume analyticity of the boundary two point function, which
means that the Cardy-Lewellen constraints remain unweakened. This enables us to
derive unambiguously the desired b^{-2}/2-shift equations. They serve as
important additional consistency conditions. For some regular branes, we also
derive 1/2-shift equations that were not known previously. Case by case, we
discuss possible solutions to the enlarged system of constraints. We find that
the well-known irregular continuous AdS_2 branes are consistent with our new
factorization constraint. Furthermore, we establish the existence of a new type
of brane: The shift equations in a certain regular discrete case possess a
non-trivial solution that we write down explicitly. All other types are found
to be inconsistent when using our second constraint. We discuss these results
in view of the Hosomichi-Ribault proposal and some of our earlier results on
the derivation of b^{-2}/2-shift equations.


title: Approximate Joint Measurability of Spin Along Two Directions

abstract:
  We study the existence of jointly measurable POVM approximations to two
non-commuting sharp spin observables. We compare two different ways to specify
optimal approximations.


title: Detection of new variable stars in the SMC cluster NGC 121

abstract:
  New candidate variable stars have been identified in the Small Magellanic
Cloud cluster NGC121, by applying both the image subtraction technique (ISIS,
Alard 2000) and the Welch & Stetson (1993) detection method to HST WFPC2
archive and ACS proprietary images of the cluster. The new candidate variable
stars are located from the cluster's Main Sequence up to Red Giant Branch.
Twenty-seven of them fall on the cluster Horizontal Branch and are very likely
RR Lyrae stars. They include the few RR Lyrae stars already discussed by Walker
& Mack (1988). We also detected 20 Dwarf Cepheid candidates in the central
region of NGC121. Our results confirm the "true" globular cluster nature of
NGC121, a cluster that is at the young end of the Galactic globulars' age
range.


title: On spectrum of vacuum energy

abstract:
  We discuss the problem of the spectral function of vacuum energy. In
traditional approach the ultraviolet divergencies of the vacuum energy are
cancelled by imposing relations between different quantum fields and their
masses. The emergent theories suggest that the microscopic degrees of the
underlying quantum vacuum add to the spectral function and their contribution
cancels the diverging zero point energy of quantum fields. Examples of the
spectral function of the vacuum energy in the condensed-matter systems with
relativity emerging at low energy are presented. In the Sakharov induced
gravity situation may be even more dramatic: only microscopic (Planck scale)
constituent fields contribute to the vacuum energy, while the diverging
zero-point energy of emergent quantum field (gravitational field) is missing.
On the other hand consideration of the fermionic condensed matter systems
suggests that emergent relativistic fermionic quasiparticles contribute in
conventional way as Dirac vacuum.


title:
Prospects for identified leading particle correlation at LHC and in
  ALICE

abstract:
  Azimuthal di-hadron correlations play important role in the characterization
of the medium created in heavy-ion collisions at RHIC. Moreover, as a novel
phenomenon, strong modification of the away-side correlation is observed in
Au+Au with respect to p+p collisions. Below the exclusive jet reconstruction
threshold at LHC, leading particle correlations will provide access to the
regime where hard scatterings and bulk medium properties can be simultaneously
studied. Leading particle correlations can be extended to very low transverse
momenta via the tracking and particle identification capabilities of ALICE, to
the coalescence and hydrodynamic domains. In preparation for the first p+p and
Pb+Pb collisions of LHC, we present prospects on leading particle correlations
with identified particles in ALICE.


title: Absence of time reversal symmetry breaking in La_{2-x}Sr_{x}CuO_{4}

abstract:
  We have performed zero-field muon spin rotation measurements on single
crystals of La_{2-x}Sr_{x}CuO_{4} to search for spontaneous currents in the
pseudo-gap state. By comparing measurements on materials across the phase
diagram, we put strict upper limits on any possible time-reversal symmetry
breaking fields that could be associated with the pseudo-gap. Comparison
between experimental limits and proposed circulating current states effectively
eliminates the possibility that such states exist in this family of materials.


title:
Temperature and momentum dependence of single-particle properties in hot
  asymmetric nuclear matter

abstract:
  We have studied the effects of momentum dependent interactions on the
single-particle properties of hot asymmetric nuclear matter. In particular, the
single-particle potential of protons and neutrons as well as the symmetry
potential have been studied within a self-consistent model using a momentum
dependent effective interaction. In addition, the isospin splitting of the
effective mass has been derived from the above model. In each case temperature
effects have been included and analyzed. The role of the specific
parametrization of the effective interaction used in the present work has been
investigated. It has been concluded that the behavior of the symmetry potential
depends strongly on the parametrization of the interaction part of the energy
density and the momentum dependence of the regulator function. The effects of
the parametrization have been found to be less pronounced on the isospin mass
splitting.


title:
Critical wetting of a class of nonequilibrium interfaces: A computer
  simulation study

abstract:
  Critical wetting transitions under nonequilibrium conditions are studied
numerically and analytically by means of an interface-displacement model
defined by a Kardar-Parisi-Zhang equation, plus some extra terms representing a
limiting, short-ranged attractive wall. Its critical behavior is characterized
in detail by providing a set of exponents for both the average height and the
surface order-parameter in one dimension. The emerging picture is qualitatively
and quantitatively different from recently reported mean-field predictions for
the same problem. Evidence is shown that the presence of the attractive wall
induces an anomalous scaling of the interface local slopes.


title:
High-precision determination of universal amplitude ratios for the q=3
  Potts model in 2d

abstract:
  Monte Carlo simulations and series expansion data for the energy, specific
heat, magnetization and susceptibility of the 3-state Potts model on the square
lattice are analyzed in the vicinity of the critical point in order to estimate
universal combinations of critical amplitudes.


title: Algebraic Modules and the Auslander--Reiten Quiver

abstract:
  Recall that an algebraic module is a KG-module that satisfies a polynomial
with integer coefficients, with addition and multiplication given by direct sum
and tensor product. In this article we prove that non-periodic algebraic
modules are very rare, and that if the complexity of an algebraic module is at
least 3, then it is the only algebraic module on its component of the (stable)
Auslander--Reiten quiver. We include a strong conjecture on the relationship
between periodicity and algebraicity.


title:
IR finiteness of the ghost dressing function from numerical resolution
  of the ghost SD equation

abstract:
  We solve numerically the Schwinger-Dyson (SD hereafter) ghost equation in the
Landau gauge for a given gluon propagator finite at k=0 (alpha_gluon=1) and
with the usual assumption of constancy of the ghost-gluon vertex ; we show that
there exist two possible types of ghost dressing function solutions, as we have
previously inferred from analytical considerations : one singular at zero
momentum, satisfying the familiar relation alpha_gluon+2 alpha_ghost=0 between
the infrared exponents of the gluon and ghost dressing functions(in short,
respectively alpha_G and alpha_F) and having therefore alpha_ghost=-1/2, and
another which is finite at the origin (alpha_ghost=0), which violates the
relation. It is most important that the type of solution which is realized
depends on the value of the coupling constant. There are regular ones for any
coupling below some value, while there is only one singular solution, obtained
only at a critical value of the coupling. For all momenta k<1.5 GeV where they
can be trusted, our lattice data exclude neatly the singular one, and agree
very well with the regular solution we obtain at a coupling constant compatible
with the bare lattice value.


title: Stability of RVB hole stripes in high-temperature superconductors

abstract:
  Indications of density-wave states in underdoped cuprates, coming from recent
STM (scanning tunneling microscopy) and Hall-resistance measurements, have
raised new concerns whether stripes could be stabilized in the superconducting
phase of cuprate materials, even in the absence of antiferromagnetism. Here, we
investigate this issue using state-of-the-art quantum Monte Carlo calculations
of a $t-J$ model. In particular we consider the stability of unidirectional
hole domains in a modulated superconducting background, by taking into account
the effect of tetragonal-lattice distortions, next-nearest neighbor hopping and
long-range Coulomb repulsion.


title: On the Tensor Products of Modules for Dihedral 2-Groups

abstract:
  Recall that an algebraic module is a KG-module that satisfies a polynomial
with integer coefficients, with addition and multiplication given by direct sum
and tensor product. In this article we prove that if L is a component of the
(stable) Auslander-Reiten quiver for a dihedral 2-group consisting of
non-periodic modules, then there is at most one algebraic module on L.


title: Spin - or, actually: Spin and Quantum Statistics

abstract:
  The history of the discovery of electron spin and the Pauli principle and the
mathematics of spin and quantum statistics are reviewed. Pauli's theory of the
spinning electron and some of its many applications in mathematics and physics
are considered in more detail. The role of the fact that the tree-level
gyromagnetic factor of the electron has the value g = 2 in an analysis of
stability (and instability) of matter in arbitrary external magnetic fields is
highlighted. Radiative corrections and precision measurements of g are
reviewed. The general connection between spin and statistics, the CPT theorem
and the theory of braid statistics are described.


title: Probability sum rules and consistent quantum histories

abstract:
  An example shows that weak decoherence is more restrictive than the minimal
logical decoherence structure that allows probabilities to be used consistently
for quantum histories. The probabilities in the sum rules that define minimal
decoherence are all calculated by using a projection operator to describe each
possibility for the state at each time. Weak decoherence requires more sum
rules. They bring in additional variables, that require different measurements
and a different way to calculate probabilities, and raise questions of
operational meaning. The example shows that extending the linearly positive
probability formula from weak to minimal decoherence gives probabilities that
are different from those calculated in the usual way using the Born and von
Neumann rules and a projection operator at each time.


title:
Schatten p-norm inequalities related to a characterization of inner
  product spaces

abstract:
  Let $A_1, ... A_n$ be operators acting on a separable complex Hilbert space
such that $\sum_{i=1}^n A_i=0$. It is shown that if $A_1, ... A_n$ belong to a
Schatten $p$-class, for some $p>0$, then 2^{p/2}n^{p-1} \sum_{i=1}^n
\|A_i\|^p_p \leq \sum_{i,j=1}^n\|A_i\pm A_j\|^p_p for $0<p\leq 2$, and the
reverse inequality holds for $2\leq p<\infty$. Moreover, \sum_{i,j=1}^n\|A_i\pm
A_j\|^2_p \leq 2n^{2/p} \sum_{i=1}^n \|A_i\|^2_p for $0<p\leq 2$, and the
reverse inequality holds for $2\leq p<\infty$. These inequalities are related
to a characterization of inner product spaces due to E.R. Lorch.


title: Dynamical randomness, information, and Landauer's principle

abstract:
  New concepts from nonequilibrium thermodynamics are used to show that
Landauer's principle can be understood in terms of time asymmetry in the
dynamical randomness generated by the physical process of the erasure of
digital information. In this way, Landauer's principle is generalized, showing
that the dissipation associated with the erasure of a sequence of bits produces
entropy at the rate $k_{{\rm B}}I$ per erased bit, where $I$ is Shannon's
information per bit.


title: Non Poissonian statistics in a low density fluid

abstract:
  Our interest goes to the collisional statistics in an arbitrary interacting
fluid. We show that even in the low density limit and contrary to naive
expectation, the number of collisions experienced by a tagged particle in a
given time does not obey Poisson law, and that conversely, the free flight time
distribution is not a simple exponential. As an illustration, the hard sphere
fluid case is worked out in detail. For this model, we quantify analytically
those deviations and successfully compare our predictions against molecular
dynamics simulations.


title:
Classification of solutions to the higher order Liouville's equation on
  R^{2m}

abstract:
  We classify the solutions to the equation (- \Delta)^m u=(2m-1)!e^{2mu} on
R^{2m} giving rise to a metric g=e^{2u}g_{R^{2m}} with finite total
$Q$-curvature in terms of analytic and geometric properties. The analytic
conditions involve the growth rate of u and the asymptotic behaviour of \Delta
u(x) as |x|\to \infty. As a consequence we give a geometric characterization in
terms of the scalar curvature of the metric e^{2u}g_{R^{2m}} at infinity, and
we observe that the pull-back of this metric to $S^{2m}$ via the stereographic
projection can be extended to a smooth Riemannian metric if and only if it is
round.


title: A Symmetry Breaking Model for X Chromosome Inactivation

abstract:
  In mammals, dosage compensation of X linked genes in female cells is achieved
by inactivation of one of their two X chromosomes which is randomly chosen. The
earliest steps in X-inactivation (XCI), namely the mechanism whereby cells
count their X chromosomes and choose between two equivalent X, remain
mysterious. Starting from the recent discovery of X chromosome colocalization
at the onset of X-inactivation, we propose a Statistical Mechanics model of
XCI, which is investigated by computer simulations and checked against
experimental data. Our model describes how a `blocking factor' complex is
self-assembled and why only one is formed out of many diffusible molecules,
resulting in a spontaneous symmetry breaking (SB) in the binding to two
identical chromosomes. These results are used to derive a scenario of
biological implications describing all current experimental evidences, e.g.,
the importance of colocalization.


title:
Strength stimuli on the quadriceps femoris influences the physiological
  tremor of the index finger

abstract:
  The influence of fatiguing stimuli applied to the quadriceps femoris on the
tremor of the index finger on sixteen healthy subjects has been investigated,
by measuring the acceleration and the electromyography activity of the extensor
digitorum at two different speeds. No significant changes in the basal
condition could be measured at 0.52 rad/s. However, at 1.05 rad/s the tremor
amplitude (12.23%, p<0.05) and the electromyography activity (20.19%, p<0.05)
increased in the time domain. In the frequential domain, the peak associated to
the acceleration increased in 26.30% (p<0.05), while the electromiography
activity experienced an increase of 81.34% (p<0.05). The largest change in
frequency took place in the range 7-17 Hz. The discussion of the results leads
to the conclusion that the supraespinal mechanism is responsible for the
measured effect.


title:
Ab initio study of transport properties in defected carbon nanotubes: an
  O(N) approach

abstract:
  A combination of ab initio simulations and linear-scaling Green's functions
techniques is used to analyze the transport properties of long (up to one
micron) carbon nanotubes with realistic disorder. The energetics and the
influence of single defects (mono- and di-vacancies) on the electronic and
transport properties of single-walled armchair carbon nanotubes are analyzed as
a function of the tube diameter by means of the local orbital first-principles
Fireball code. Efficient O(N) Green's functions techniques framed within the
Landauer-Buttiker formalism allow a statistical study of the nanotube
conductance averaged over a large sample of defected tubes and thus extraction
of the nanotubes localization length. Both the cases of zero and room
temperature are addressed.


title: On the cross-section peaks for a heavy quark bound state

abstract:
  We discuss the values of resonance peaks of the cross-section of a heavy
quark bound state obtained by means of a Green function method applied to a
Coulombic model and compare the result to the Upsilon and J/psi data.


title: On Hydrodynamic Correlations in Low-Dimensional Interacting Systems

abstract:
  Low-dimensional systems are an important field of current theoretical and
experimental research. Recent technological developments provide many possible
realizations of effectively one-dimensional systems. These devices promise to
give us access to a new range of phenomena. It is therefore very interesting to
develop theoretical methods specific for such systems to model their behavior
and calculate the correlators of the resulting theory. Incidentally, one such
method exists and is known as Bosonization. It can be applied to
one-dimensional systems and effectively describes low energy excitations in a
universal way. We use the example of a correlator known as the Emptiness
Formation Probability to show that Bosonization fails to describe some long
range correlators corresponding to large disturbances (the EFP measures the
probability for the ground state of the system to develop a region without
particles). We trace this failure to the fact that Bosonization is constructed
as a linear approximation of the full theory and we set up to develop a
collective description with the required non-linearity. The resulting scheme is
essentially a Hydrodynamic paradigm for quantum systems. We show how to
construct such a hydrodynamic description for a variety of exactly integrable
models and illustrate how it can be used to make new predictions. For the
special case of the spin-1/2 XY model we take advantage of the structure of the
model to express the EFP as a determinant of a very special type of matrix,
known as Toeplitz Matrix. We use the theory of Toeplitz determinants to
calculate the asymptotic behavior of the EFP in the XY model and discuss its
relation with the criticality of the theory.


title:
Triplet and Singlet Excitations in the Valence Bond Crystal Phase of
  Kagome Lattice Heisenberg Model

abstract:
  A proposed ground state for the Kagome Lattice Heisenberg Model (KLHM)
consists of a Valence Bond Crystal (VBC) with a 36-site unit cell. We calculate
the low-lying triplet and singlet excitations in the VBC phase for the
infinite-lattice model and for the 36-site cluster. For the infinite lattice,
the lowest triplet excitation is found to have a spin gap of approximately
$0.08 \pm 0.02 J$ and a bandwidth of only about $0.01 J$. For the 36-site
cluster, consisting of a single unit cell with periodic boundary conditions,
there are substantial finite-size effects: the spin gap there is estimated to
be approximately $0.2 J$, close to the exact diagonalization result of $0.164
J$. The triplet excitations attract one another and form many bound states in
the spin-singlet channel. We find a large number of such bound states for the
36-site cluster, many of which appear to lie below the spin gap, again in
agreement with the results from exact diagonalization.


title:
All-electron quantum Monte Carlo calculations for the noble gas atoms He
  to Xe

abstract:
  We report all-electron variational and diffusion quantum Monte Carlo (VMC and
DMC) calculations for the noble gas atoms He, Ne, Ar, Kr, and Xe. The
calculations were performed using Slater-Jastrow wave functions with
Hartree-Fock single-particle orbitals. The quality of both the optimized
Jastrow factors and the nodal surfaces of the wave functions declines with
increasing atomic number Z, but the DMC calculations are tractable and well
behaved in all cases. We discuss the scaling of the computational cost of DMC
calculations with Z.


title: Warming rays in cluster cool cores

abstract:
  We present a model of cosmic ray heating of clusters' cores that reproduces
the observed temperature distribution in clusters by using an energy balance
condition in which the emitted X-ray energy is supplied by the hadronic cosmic
rays, which act as warming rays (WRs). The temperature profile of the IC gas is
correlated with the WR pressure distribution and, consequently, with the
non-thermal emission (radio, hard X-ray and gamma-ray) induced by the
interaction of the WRs with the IC gas and magnetic field. The temperature
distribution of the IC gas in both cool-core and non cool-core clusters is
successfully predicted from the measured IC gas density distribution. Under
this contraint, the WR model is also able to reproduce the thermal and
non-thermal pressure distribution in clusters, as well as their radial entropy
distribution. The WR model provides other observable features: a correlation of
the pressure ratio (WRs to thermal IC gas) with the inner cluster temperature
T_{inner}, a correlation of the gamma-ray luminosity with T_{inner}, a
substantial number of cool-core clusters observable with the GLAST-LAT
experiment, a surface brightness of radio halos in cool-core clusters that
recovers the observed one, a hard X-ray emission from cool-core clusters that
is systematically lower than the observed limits and yet observable with the
next generation HXR experiments like Simbol-X. The specific theoretical
properties and the multi-frequency distribution of the e.m. signals predicted
in the WR model render it quite different from the other models proposed for
the heating of clusters' cool-cores. Such differences make it possible to prove
or disprove our model as an explanation of the cooling-flow problems on the
basis of multi-frequency observations of galaxy clusters.


title: Paschen is Partially Back

abstract:
  We present a discussion of the partial Paschen-Back (PB) effect in magnetic
Ap stars. An overview of the theory is illustrated with examples of how
splittings deviate non-linearly from the simple Zeeman picture; normally
forbidden ``ghost lines'' appear in strong fields. Resulting asymmetric stellar
Stokes profiles for a dipolar magnetic geometry are shown for the FeII 6149
line and it is established that PB lines may be subject to wavelength shifts.
Modelling of Stokes profiles in the PB regime opens exciting new diagnostics.


title: Numerical tests of AdS/CFT at strong coupling

abstract:
  We study various correlation functions (two and three point functions) in a
large $N$ matrix model of six commuting matrices with a numerical Monte Carlo
algorithm. This is equivalent to a model of a gas of particles in six
dimensions with a confining quadratic potential and logarithmic repulsions at
finite temperature, where we are measuring the leading order non-gaussianities
in the thermal fluctuations.
  This is a simplified model of the low energy dynamics of N=4 SYM at strong
coupling. We find strong evidence that the simplified matrix model matches with
the dual gravitational description of three point functions in the AdS/CFT
correspondence.


title:
Modelling the incomplete Paschen-Back effect in the spectra of magnetic
  Ap stars

abstract:
  We present first results of a systematic investigation of the incomplete
  Paschen-Back effect in magnetic Ap stars. A short overview of the theory is
followed by a demonstration of how level splittings and component strengths
change with magnetic field strength for some lines of special astrophysical
interest. Requirements are set out for a code which allows the calculation of
full Stokes spectra in the Paschen-Back regime and the behaviour of Stokes I
and V profiles of transitions in the multiplet 74 of FeII is discussed in some
detail. It is shown that the incomplete Paschen-Back effect can lead to
noticeable line shifts which strongly depend on total multiplet strength,
magnetic field strength and field direction. Ghost components (which violate
the normal selection rule on J) show up in strong magnetic fields but are
probably unobservable. Finally it is shown that measurements of the integrated
magnetic field modulus $H_s$ are not adversely affected by the Paschen-Back
effect, and that there is a potential problem in (magnetic) Doppler mapping if
lines in the Paschen-Back regime are treated in the Zeeman approximation.


title: Static perfect fluids with Pant-Sah equations of state

abstract:
  We analyze the 3-parameter family of exact, regular, static, spherically
symmetric perfect fluid solutions of Einstein's equations (corresponding to a
2-parameter family of equations of state) due to Pant and Sah and
"rediscovered" by Rosquist and the present author. Except for the Buchdahl
solutions which are contained as a limiting case, the fluids have finite radius
and are physically realistic for suitable parameter ranges. The equations of
state can be characterized geometrically by the property that the 3-metric on
the static slices, rescaled conformally with the fourth power of any linear
function of the norm of the static Killing vector, has constant scalar
curvature. This local property does not require spherical symmetry; in fact it
simplifies the the proof of spherical symmetry of asymptotically flat solutions
which we recall here for the Pant-Sah equations of state. We also consider a
model in Newtonian theory with analogous geometric and physical properties,
together with a proof of spherical symmetry of the asymptotically flat
solutions.


title: Scheme for adding electron-nucleus cusps to Gaussian orbitals

abstract:
  A simple scheme is described for introducing the correct cusps at nuclei into
orbitals obtained from Gaussian basis set electronic structure calculations.
The scheme is tested with all-electron variational quantum Monte Carlo (VMC)
and diffusion quantum Monte Carlo (DMC) methods for the Ne atom, the H2
molecule, and 55 molecules from a standard benchmark set. It greatly reduces
the variance of the local energy in all cases and slightly improves the
variational energy. This scheme yields a general improvement in the efficiency
of all-electron VMC and DMC calculations using Gaussian basis sets.


title: Four-nucleon system with $\Delta$-isobar excitation

abstract:
  The four-nucleon bound state and scattering below three-body breakup
threshold are described based on the realistic coupled-channel potential CD
Bonn + $\Delta$ which allows the excitation of a single nucleon to a $\Delta$
isobar. The Coulomb repulsion between protons is included. In the four-nucleon
system the two-baryon coupled-channel potential yields effective two-, three-
and four-nucleon forces, mediated by the $\Delta$ isobar and consistent with
each other and with the underlying two-nucleon force. The effect of the
four-nucleon force on the studied observables is much smaller than the effect
of the three-nucleon force. The inclusion of the $\Delta$ isobar is unable to
resolve the existing discrepancies with the experimental data.


title: Epitaxial graphene transistors on SiC substrates

abstract:
  This paper describes the behavior of top gated transistors fabricated using
carbon, particularly epitaxial graphene on SiC, as the active material. In the
past decade research has identified carbon-based electronics as a possible
alternative to silicon-based electronics. This enthusiasm was spurred by high
carbon nanotube carrier mobilities. However, nanotube production, placement,
and control are all serious issues. Graphene, a thin sheet of graphitic carbon,
can overcome some of these problems and therefore is a promising new electronic
material. Although graphene devices have been built before, in this work we
provide the first demonstration and systematic evaluation of arrays of a large
number of transistors entirely produced using standard microelectronics
methods. Graphene devices presented feature high-k dielectric, mobilities up to
5000 cm2/Vs and, Ion/Ioff ratios of up to 7, and are methodically analyzed to
provide insight into the substrate properties. Typical of graphene, these
micron-scale devices have negligible band gaps and therefore large leakage
currents.


title: Scalar form factors and nuclear interactions

abstract:
  The scalar-isoscalar term in the two-pion exchange $NN$ potential is
abnormally large and does not respect the hierarchy of effects predicted by
chiral perturbation theory. We argue that this anomaly is associated with
non-perturbative effects, which are also present in the $\pi N$ scalar form
factor.


title:
Analysis and interpretation of a fast limb CME with eruptive prominence,
  C-flare and EUV dimming

abstract:
  Coronal Mass ejections or CMEs are large dynamical solar-corona events. The
mass balance and kinematics of a fast limb CME, including its prominence
progenitor and the associated flare, will be compared with computed magnetic
structures to look for their origin and effect.
  Multi-wavelength ground-based and space-borne observations are used to study
a fast W-limb CME event of December 2, 2003, taking into account both on and
off disk observations. Its erupting prominence is measured at high cadence with
the Pic du Midi full H-alpha line-flux imaging coronagraph. EUV images from
space instruments are processed including difference imaging. SOHO/LASCO images
are used to study the mass excess and motions. A fast bright expanding coronal
loop is identified in the region recorded slightly later by GOES as a C7.2
flare, followed by a brightening and an acceleration phase of the erupting
material with both cool and hot components. The total coronal radiative flux
dropped by 5 percent in the EUV channels, revealing a large dimming effect at
and above the limb. The typical 3-part structure observed 1 hour later shows a
core shaped similarly to the eruptive filament/prominence. The total measured
mass of the escaping CME (1.5x10to16 g from C2 LASCO observations) definitely
exceeds the estimated mass of the escaping cool prominence material although
assumptions made to analyse the Ha erupting prominence, as well as the
corresponding EUV darkening of the filament observed several days before, made
this evaluation uncertain by a factor of 2. From the current free extrapolation
we discuss the shape of the magnetic neutral surface and a possible scenario
leading to an instability, including the small scale dynamics inside and around
the filament.


title:
Energetics and Structural Properties of Trapped Two-Component Fermi
  Gases

abstract:
  Using two different numerical methods, we study the behavior of two-component
Fermi gases interacting through short-range s-wave interactions in a harmonic
trap. A correlated Gaussian basis-set expansion technique is used to determine
the energies and structural properties, i.e., the radial one-body densities and
pair distribution functions, for small systems with either even or odd $N$, as
functions of the s-wave scattering length and the mass ratio $\kappa$ of the
two species. Particular emphasis is put on a discussion of the angular momentum
of the system in the BEC-BCS crossover regime. At unitarity, the excitation
spectrum of the four-particle system with total angular momentum L=0 is
calculated as a function of the mass ratio $\kappa$. The results are analyzed
from a hyperspherical perspective, which offers new insights into the problem.
Additionally, fixed-node diffusion Monte Carlo calculations are performed for
equal-mass Fermi gases with up to N=30 atoms. We focus on the odd-even
oscillations of the ground state energy of the equal-mass unitary system having
up to N=30 particles, which are related to the excitation gap of the system.
Furthermore, we present a detailed analysis of the structural properties of
these systems.


title: A greedy approach to sparse canonical correlation analysis

abstract:
  We consider the problem of sparse canonical correlation analysis (CCA), i.e.,
the search for two linear combinations, one for each multivariate, that yield
maximum correlation using a specified number of variables. We propose an
efficient numerical approximation based on a direct greedy approach which
bounds the correlation at each stage. The method is specifically designed to
cope with large data sets and its computational complexity depends only on the
sparsity levels. We analyze the algorithm's performance through the tradeoff
between correlation and parsimony. The results of numerical simulation suggest
that a significant portion of the correlation may be captured using a
relatively small number of variables. In addition, we examine the use of sparse
CCA as a regularization method when the number of available samples is small
compared to the dimensions of the multivariates.


title:
The Parsec-Scale Jets of the TeV Blazars H 1426+428, 1ES 1959+650, and
  PKS 2155-304: 2001-2004

abstract:
  We present Very Long Baseline Array (VLBA) observations of the TeV blazars H
1426+428, 1ES 1959+650, and PKS 2155-304 obtained during the years 2001 through
2004. We observed H 1426+428 at four epochs at 8 GHz, and found that its
parsec-scale structure consisted of a ~17 mJy core and a single ~3 mJy jet
component with an apparent speed of 2.09 +/- 0.53c. The blazar 1ES 1959+650 was
observed at three epochs at frequencies of 15 and 22 GHz. Spectral index
information from these dual-frequency observations was used to definitively
identify the core of the parsec-scale structure. PKS 2155-304 was observed at a
single epoch at 15 GHz with dual-circular polarization, and we present the
first VLBI polarimetry image of this source. For 1ES 1959+650 and PKS 2155-304,
the current observations are combined with the VLBA observations from our
earlier paper to yield improved apparent speed measurements for these sources
with greatly reduced measurement errors. The new apparent speed measured for
component C2 in 1ES 1959+650 is 0.00 +/- 0.04c (stationary), and the new
apparent speed measured for component C1 in PKS 2155-304 is 0.93 +/- 0.31c. We
combine the new apparent speed measurements from this paper with the apparent
speeds measured in TeV blazar jets from our earlier papers to form a current
set of apparent speed measurements in TeV HBLs. The mean peak apparent pattern
speed in the jets of the TeV HBLs is about 1c. We conclude the paper with a
detailed discussion of the interpretation of the collected VLBA data on TeV
blazars in the context of current theoretical models for the parsec-scale
structure of TeV blazar jets.


title:
New method to integrate 2+1 wave equations with Dirac's delta functions
  as sources

abstract:
  Gravitational perturbations in a Kerr black hole background can not be
decomposed into simple tensor harmonics in the time domain. Here, we make the
mode decomposition only in the azimuthal direction and discuss the resulting
(2+1)-dimensional Klein-Gordon differential equation for scalar perturbations
with a two dimensional Dirac's $\delta$-function as a source representing a
point particle orbiting a much larger black hole. To make this equation
amenable for numerical integrations we explicitly remove analytically the
singular behavior of the source and compute a global effective source for the
corresponding waveform.


title:
Construction of an Edwards' probability measure on
  $\mathcal{C}(\mathbb{R}_+,\mathbb{R})$

abstract:
  In this article, we prove that the measures $\mathbb{Q}_T$ associated to the
one-dimensional Edwards' model on the interval $[0,T]$ converge to a limit
measure $\mathbb{Q}$ when $T$ goes to infinity, in the following sense: for all
$s\geq0$ and for all events $\Lambda_s$ depending on the canonical process only
up to time $s$, $\mathbb{Q}_T(\Lambda_s)\rightarrow\mathbb{Q}(\Lambda_s)$.
Moreover, we prove that, if $\mathbb{P}$ is Wiener measure, there exists a
martingale $(D_s)_{s\in\mathbb{R}_+}$ such that $\mathbb{Q}(\Lambda_s)
=\mathbb{E}_{\mathbb{P}}(\mathbh{1}_{\Lambda_s}D_s)$, and we give an explicit
expression for this martingale.


title:
The Equation of a Light Leptonic Magnetic Monopole and its Experimental
  Aspects

abstract:
  The present theory is closely related to Dirac's equation of the electron,
but not to his magnetic monopole theory, except for his relation between
electric and magnetic charge. The theory is based on the fact, that the
massless Dirac equation admits a second electromagnetic coupling, deduced from
a pseudo-scalar gauge invariance. The equation thus obtained has the symmetry
laws of a massless leptonic, magnetic monopole, able to interact weakly. We
give a more precise form of the Dirac relation between electric and magnetic
charges and a quantum form of the Poincare first integral. In the Weyl
representation our equation splits into P-conjugated monopole and antimonopole
equations with the correct electromagnetic coupling and opposite chiralities,
predicted by P. Curie. Charge-conjugated monopoles are symmetric in space and
not in time (contrary to the electric particles), an important fact for the
vacuum polarization. Our monopoles are magnetically excited neutrinos, which
leads to experimental consequences. These monopoles are assumed to be produced
by electromagnetic pulses or arcs, leading to nuclear transmutations and, for
beta radioactive elements, a shortening of the life time and the emission of
monopoles instead of neutrinos in a magnetic field. A corresponding discussion
is given.


title:
Discrete approximation of a stable self-similar stationary increments
  process

abstract:
  The aim of this paper is to present a result of discrete approximation of
some class of stable self-similar stationary increments processes. The
properties of such processes were intensively investigated, but little is known
on the context in which such processes can arise. To our knowledge,
discretisation and convergence theorems are available only in the case of
stable L\'evy motions and fractional Brownian motions. This paper yields new
results in this direction. Our main result is the convergence of the random
rewards schema, which was firstly introduced by Cohen and Samorodnitsky, and
that we consider in a more general setting. Strong relationships with Kesten
and Spitzer's random walk in random sceneries are evidenced. Finally, we study
some path properties of the limit process.


title:
Filtration method characterizing the reversibility of colloidal fouling
  layers at a membrane surface: analysis through critical flux and osmotic
  pressure

abstract:
  A filtration procedure was developed to measure the reversibility of fouling
during cross-flow filtration based on the square wave of applied pressure. The
principle of this method, the apparatus required, and the associated
mathematical relationships are detailed. This method allows for differentiating
the reversible accumulation of matter on, and the irreversible fouling of, a
membrane surface. Distinguishing these two forms of attachment to a membrane
surface provides a means by which the critical flux may be determined. To
validate this method, experiments were performed with a latex suspension at
different degrees of destabilization (obtained by the addition of salt to the
suspension) and at different cross-flow velocities. The dependence of the
critical flux on these conditions is discussed and analysed through the osmotic
pressure of the colloidal dispersion.


title: $L^\infty$-Uniqueness of Generalized SCHR\"Odinger Operators

abstract:
  The main purpose of this paper is to show that the generalized Schr\"odinger
operator ${\cal A}^Vf={1/2}\Delta f+b\nabla f-Vf$, $f\in C_0^\infty(\R^d)$, is
a pre-generator for which we can prove its $L^\infty(\R^d,dx)$-uniqueness.
Moreover, we prove the $L^1(\R^d,dx)$-uniqueness of weak solutions for the
Fokker-Planck equation associated with this pre-generator.


title: On universality of algebraic decays in Hamiltonian systems

abstract:
  Hamiltonian systems with a mixed phase space typically exhibit an algebraic
decay of correlations and of Poincare' recurrences, with numerical experiments
over finite times showing system-dependent power-law exponents. We conjecture
the existence of a universal asymptotic decay based on results for a Markov
tree model with random scaling factors for the transition probabilities.
Numerical simulations for different Hamiltonian systems support this conjecture
and permit the determination of the universal exponent.


title:
Probing the Turbulence Dissipation Range and Magnetic Field Strengths in
  Molecular Clouds

abstract:
  We study the turbulent velocity dispersion spectra of the coexistent HCN and
HCO+ molecular species as a function of length scale in the M17 star-forming
molecular cloud. We show that the observed downward shift of the ion's spectrum
relative to that of the neutral is readily explained by the existence of an
ambipolar diffusion range within which ion and neutral turbulent energies
dissipate differently. We use these observations to evaluate this decoupling
scale and show how to estimate the strength of the plane-of-the-sky component
of the embedded magnetic field in a completely novel way.


title: Semiclassical theory of the quasi two-dimensional trapped Bose gas

abstract:
  We discuss the quasi two-dimensional trapped Bose gas where the thermal
occupation of excited states in the tightly confined direction is small but
remains finite in the thermodynamic limit. We show that the semiclassical
theory describes very accurately the density profile obtained by Quantum Monte
Carlo calculations in the normal phase above the Kosterlitz--Thouless
temperature T_KT, but differs strongly from the predictions of strictly
two-dimensional mean-field theory, even at relatively high temperature. We
discuss the relevance of our findings for analyzing ultra-cold-atom experiments
in quasi two-dimensional traps.


title:
Spitzer Uncovers Active Galactic Nuclei Missed by Optical Surveys in 7
  Late-type Galaxies

abstract:
  We report the discovery using Spitzers high resolution spectrograph of 7
Active Galactic Nuclei (AGN) in a sample of 32 late-type galaxies that show no
definitive signatures of AGN in their optical spectra. Our observations suggest
that the AGN detection rate in late-type galaxies is possibly 4 times larger
than what optical spectroscopic observations alone suggest. We demonstrate
using photoionization models with an input AGN and an extreme EUV-bright
starburst ionizing radiation field that the observed mid-infrared line ratios
cannot be replicated unless an AGN contribution, in some cases as little as 10%
of the total galaxy luminosity, is included. These models show that when the
fraction of the total luminosity due to the AGN is low, optical diagnostics are
insensitive to the presence of the AGN. In this regime of parameter space, the
mid-infrared diagnostics offer a powerful tool for uncovering AGN missed by
optical spectroscopy. The AGN bolometric luminosities in our sample range from
~3 X 10^41 - ~2 X 10^43 ergs s^-1, which, based on the Eddington limit,
corresponds to a lower mass limit for the black hole that ranges from ~3 X
10^3Mdot to as high as ~1.5 X 10^5Mdot. These lower mass limits however do not
put a strain on the well-known relationship between the black hole mass and the
host galaxy's stellar velocity dispersion established in predominantly
early-type galaxies. Our findings add to the growing evidence that black holes
do form and grow in low-bulge environments and that they are significantly more
common than optical studies indicate.


title:
Harnessing and control of optical rogue waves in supercontinuum
  generation

abstract:
  We present a numerical study of the evolution dynamics of ``optical rogue
waves'', statistically-rare extreme red-shifted soliton pulses arising from
supercontinuum generation in photonic crystal fiber [D. R. Solli et al. Nature
Vol. 450, 1054-1058 (2007)]. Our specific aim is to use nonlinear Schrodinger
equation simulations to identify ways in which the rogue wave dynamics can be
actively controlled, and we demonstrate that rogue wave generation can be
enhanced by an order of magnitude through a small modulation across the input
pulse envelope and effectively suppressed through the use of a sliding
frequency filter.


title: Protective Measurements

abstract:
  A review of protective measurements. Protective measurement is a method for
measuring an expectation value of an observable on a single quantum system. The
quantum state of the system can be protected by a potential, when the state is
a nondegenerate energy eigenstate with a known gap to neighboring states, or
via Zeno effect by frequent projection measurements.


title: Infrared singularities in Landau gauge Yang-Mills theory

abstract:
  We present a more detailed picture of the infrared regime of Landau gauge
Yang-Mills theory. This is done within a novel framework that allows one to
take into account the influence of finite scales within an infrared power
counting analysis. We find that there are two qualitatively different infrared
fixed points of the full system of Dyson-Schwinger equations. The first extends
the known scaling solution, where the ghost dynamics is dominant and gluon
propagation is strongly suppressed. It features in addition to the strong
divergences of gluonic vertex functions in the previously considered uniform
scaling limit, when all external momenta tend to zero, also weaker kinematic
divergences, when only some of the external momenta vanish. The second solution
represents the recently proposed decoupling scenario where the gluons become
massive and the ghosts remain bare. In this case we find that none of the
vertex functions is enhanced, so that the infrared dynamics is entirely
suppressed. Our analysis also provides a strict argument why the Landau gauge
gluon dressing function cannot be infrared divergent.


title:
Real forms of very extended Kac-Moody algebras and theories with eight
  supersymmetries

abstract:
  We consider all theories with eight supersymmetries whose reduction to three
dimensions gives rise to scalars that parametrise symmetric manifolds. We
conjecture that these theories are non-linear realisations of very-extended
Kac-Moody algebras for suitable choices of real forms. We show for the most
interesting cases that the bosonic sector of the supersymmetric theory is
precisely reproduced by the corresponding non-linear realisation.


title:
Clarifying the nature of the brightest submillimetre sources:
  interferometric imaging of LH850.02

abstract:
  We present high-resolution interferometric imaging of LH850.02, the brightest
850- and 1200-micron submillimetre (submm) galaxy in the Lockman Hole. Our
observations were made at 890 micron with the Submillimetre Array (SMA). Our
high-resolution submm imaging detects LH850.02 at >6-sigma as a single compact
(size < 1 arcsec or < 8 kpc) point source and yields its absolute position to
~0.2-arcsec accuracy. LH850.02 has two alternative radio counterparts within
the SCUBA beam (LH850.02N & S), both of which are statistically very unlikely
to be so close to the SCUBA source position by chance. However, the precise
astrometry from the SMA shows that the submm emission arises entirely from
LH850.02N, and is not associated with LH850.02S (by far the brighter of the two
alternative identifications at 24-micron). Fits to the optical-infrared
multi-colour photometry of LH850.02N & S indicate that both lie at z~3.3, and
are therefore likely to be physically associated. At these redshifts, the 24
micron--to--submm flux density ratios suggest that LH850.02N has an Arp220-type
starburst-dominated far-IR SED, while LH850.02S is more similar to Mrk231, with
less dust-enshrouded star-formation activity, but a significant contribution at
24-micron (rest-frame ~5-6 micron) from an active nucleus. This complex mix of
star-formation and AGN activity in multi-component sources may be common in the
high redshift ultraluminous galaxy population, and highlights the need for
precise astrometry from high resolution interferometric imaging for a more
complete understanding.


title: Quiescent H2 Emission From Pre-Main Sequence Stars in Chamaeleon I

abstract:
  We report the discovery of quiescent emission from molecular hydrogen gas
located in the circumstellar disks of six pre-main sequence stars, including
two weak-line T Tauri stars (TTS), and one Herbig AeBe star, in the Chamaeleon
I star forming region. For two of these stars, we also place upper limits on
the 2->1 S(1)/1->0 S(1) line ratios of 0.4 and 0.5. Of the 11 pre-main sequence
sources now known to be sources of quiescent near-infrared hydrogen emission,
four possess transitional disks, which suggests that detectable levels of H$_2$
emission and the presence of inner disk holes are correlated. These H$_2$
detections demonstrate that these inner holes are not completely devoid of gas,
in agreement with the presence of observable accretion signatures for all four
of these stars and the recent detections of [Ne II] emission from three of
them. The overlap in [Ne II] and H$_2$ detections hints at a possible
correlation between these two features and suggests a shared excitation
mechanism of high energy photons. Our models, combined with the kinematic
information from the H$_2$ lines, locate the bulk of the emitting gas at a few
tens of AU from the stars. We also find a correlation between H$_2$ detections
and those targets which possess the largest H$\alpha$ equivalent widths,
suggesting a link between accretion activity and quiescent H$_2$ emission. We
conclude that quiescent H$_2$ emission from relatively hot gas within the disks
of TTS is most likely related to on-going accretion activity, the production of
UV photons and/or X-rays, and the evolutionary status of the dust grain
populations in the inner disks.


title: [Ne V] Emission in Optically Classified Starbursts

abstract:
  Detecting Active Galactic Nuclei (AGN) in galaxies dominated by powerful
nuclear star formation and extinction effects poses a unique challenge. Due to
the longer wavelength emission and the ionization potential of Ne^3+, infrared
[Ne V] emission lines are thought to be excellent AGN diagnostics. However,
stellar evolution models predict Wolf-Rayet stars in young stellar clusters
emit significant numbers of photons capable of creating Ne^4+. Recent
observations of [Ne V] emission in optically classified starburst galaxies
require us to investigate whether [Ne V] can arise from star-formation activity
and not an AGN. In this work, we calculate the optical and IR spectrum of gas
exposed to a young starburst and AGN SED. We find: 1) a range of parameters
where [Ne V] emission can be explained solely by star-formation and 2) a range
of relative AGN to starburst luminosities that reproduce the [Ne V]
observations, yet leaves the optical spectrum looking like a starburst. We also
find infrared emission-line diagnostics are much more sensitive to the AGN than
optical diagnostics, particularly for weak AGN. We apply our model to the
optically classified, yet [Ne V] emitting, starburst galaxy NGC 3621. We find,
when taking the IR and optical spectrum into account, about 30 - 50% of the
galaxy's total luminosity is due to an AGN. Our calculations show that [Ne V]
emission is almost always the result of AGN activity. The models presented in
this work can be used to determine the AGN contribution to a galaxy's power
output.


title: Abundances of Planetary Nebula NGC2392

abstract:
  The spectra of the planetary nebula NGC2392 is reanalysed using spectral
measurements made in the mid-infrared with the Spitzer Space Telescope. The aim
is to determine the chemical composition of this object. We also make use of
IUE and ground based spectra. Abundances determined from the mid-infrared
lines, which are insensitive to electron temperature, are used as the basis for
the determination of the composition, which are found to differ somewhat from
earlier results. The abundances found, especially the low value of helium and
oxygen, indicate that the central star was originally of rather low mass.
Abundances of phosphorus, iron, silicon and chlorine have been determined for
the first time in this nebula. The variation of electron temperature in this
nebula is very clear reaching quite high values close to the center. The
temperature of the central star is discussed in the light of the high observed
stages of ionization. The nebular information indicates the spectrum of the
star deviates considerably from a blackbody.


title:
A new method to create initially mass segregated star clusters in virial
  equilibrium

abstract:
  Mass segregation stands as one of the most robust features of the dynamical
evolution of self-gravitating star clusters. In this paper we formulate
parametrised models of mass segregated star clusters in virial equilibrium. To
this purpose we introduce mean inter-particle potentials for statistically
described unsegregated systems and suggest a single-parameter generalisation of
its form which gives a mass-segregated state. We describe an algorithm for
construction of appropriate star cluster models. Their stability over several
crossing-times is verified by following the evolution by means of direct N-body
integration.


title:
The DEEP2 Galaxy Redshift Survey: The Red Sequence AGN Fraction and its
  Environment and Redshift Dependence

abstract:
  We measure the dependence of the AGN fraction on local environment at z~1,
using spectroscopic data taken from the DEEP2 Galaxy Redshift Survey, and
Chandra X-ray data from the All-Wavelength Extended Groth Strip International
Survey (AEGIS). To provide a clean sample of AGN we restrict our analysis to
the red sequence population; this also reduces additional colour-environment
correlations. We find evidence that high redshift LINERs in DEEP2 tend to
favour higher density environments relative to the red population from which
they are drawn. In contrast, Seyferts and X-ray selected AGN at z~1 show little
(or no) environmental dependencies within the same underlying population. We
compare these results with a sample of local AGN drawn from the SDSS. Contrary
to the high redshift behaviour, we find that both LINERs and Seyferts in the
SDSS show a slowly declining red sequence AGN fraction towards high density
environments. Interestingly, at z~1 red sequence Seyferts and LINERs are
approximately equally abundant. By z~0, however, the red Seyfert population has
declined relative to the LINER population by over a factor of 7. We speculate
on possible interpretations of our results.


title: Simulating galactic outflows with kinetic supernova feedback

abstract:
  Feedback from star formation is thought to play a key role in the formation
and evolution of galaxies, but its implementation in cosmological simulations
is currently hampered by a lack of numerical resolution. We present and test a
sub-grid recipe to model feedback from massive stars in cosmological smoothed
particle hydrodynamics simulations. The energy is distributed in kinetic form
among the gas particles surrounding recently formed stars. The impact of the
feedback is studied using a suite of high-resolution simulations of isolated
disc galaxies embedded in dark halos with total mass 10^{10} and 10^{12}
Msol/h. We focus in particular on the effect of pressure forces on wind
particles within the disc, which we turn off temporarily in some of our runs to
mimic a recipe that has been widely used in the literature. We find that this
popular recipe gives dramatically different results because (ram) pressure
forces on expanding superbubbles determine both the structure of the disc and
the development of large-scale outflows. Pressure forces exerted by expanding
superbubbles puff up the disc, giving the dwarf galaxy an irregular morphology
and creating a galactic fountain in the massive galaxy. Hydrodynamic drag
within the disc results in a strong increase of the effective mass loading of
the wind for the dwarf galaxy, but quenches much of the outflow in the case of
the high-mass galaxy.


title: Where do "red and dead" early-type void galaxies come from?

abstract:
  Void regions of the Universe offer a special environment for studying
cosmology and galaxy formation, which may expose weaknesses in our
understanding of these phenomena. Although galaxies in voids are observed to be
predominately gas rich, star forming and blue, a sub-population of bright red
void galaxies can also be found, whose star formation was shut down long ago.
Are the same processes that quench star formation in denser regions of the
Universe also at work in voids?
  We compare the luminosity function of void galaxies in the 2dF Galaxy
Redshift Survey, to those from a galaxy formation model built on the Millennium
Simulation. We show that a global star formation suppression mechanism in the
form of low luminosity "radio mode" AGN heating is sufficient to reproduce the
observed population of void early-types. Radio mode heating is environment
independent other than its dependence on dark matter halo mass, where, above a
critical mass threshold of approximately M_vir~10^12.5 M_sun, gas cooling onto
the galaxy is suppressed and star formation subsequently fades. In the
Millennium Simulation, the void halo mass function is shifted with respect to
denser environments, but still maintains a high mass tail above this critical
threshold. In such void halos, radio mode heating remains efficient and red
galaxies are found; collectively these galaxies match the observed space
density without any modification to the model. Consequently, galaxies living in
vastly different large-scale environments but hosted by halos of similar mass
are predicted to have similar properties, consistent with observations.


title:
Uncovering a pressure-tuned electronic transition in BiSrYCu2O8 using
  Raman scattering and x-ray diffraction

abstract:
  We report pressure tuned Raman and x-ray diffraction data of
Bi1.98Sr2.06Y0.68Cu2O8 revealing a critical pressure at 21 GPa with anomalies
in six physical quantities: electronic Raman background, electron-phonon
coupling, spectral weight transfer from high to low frequency, density
dependent behaviour of phonon and magnon frequencies, and a compressibility
change in the c-axis. For the first time in a cuprate, mobile charge carriers,
lattice, and magnetism all show anomalies at a distinct critical pressure in
the same experimental setting. Furthermore, the Raman spectral changes are
similar to that seen traversing the superconducting dome with doping,
suggesting that the critical pressure at 21 GPa is related to the much
discussed critical point at optimal doping.


title:
Symmetry Extensions and Their Physical Reasons in the Kinetic and
  Hydrodynamic Plasma Models

abstract:
  Characteristic examples of continuous symmetries in hydrodynamic plasma
theory (partial differential equations) and in kinetic Vlasov-Maxwell models
(integro-differential equations) are considered. Possible symmetry extensions
conditional and extended symmetries are discussed. Physical reasons for these
symmetry extensions are clarified.


title: Galaxy Concentrations are Trimodal

abstract:
  We have analysed the distribution of inclination-corrected galaxy
concentrations in the Sloan Digital Sky Survey. We find that unlike most galaxy
properties, which are distributed bimodally, the distribution of concentrations
is trimodal: it exhibits three distinct peaks. The newly-discovered
intermediate peak, which consists of early-type spirals and lenticulars, may
contain ~60% of the number density and ~50% of the luminosity density of M_r <
-17 galaxies in the local universe. These galaxies are generally red and
quiescent, although the distribution contains a tail of blue star-forming
galaxies and also shows evidence of dust. The intermediate-type galaxies have
higher apparent ellipticities than either disc or elliptical galaxies, most
likely because some of the face-on intermediate types are misidentified as
ellipticals. Their physical half-light radii are smaller than the radii of
either the disc or elliptical galaxies, which may be evidence that they form
from disc fading. The existence of a distinct peak in parameter space
associated with early-type spiral galaxies and lenticulars implies that they
have a distinct formation mechanism and are not simply the smooth transition
between disc-dominated and spheroid-dominated galaxies.


title: Family symmetries and the origin of fermion masses and mixings

abstract:
  Family symmetries are possibly the most conservative extension of the
Standard Model that attempt explanations of the pattern of fermion masses and
mixings. The observed large mixing angles in the lepton sector may be the first
signal for the presence of a non-Abelian family symmetry. We investigate the
possibilities of simultaneously explaining the observed pattern of masses of
the quarks (hierarchical masses and small mixing angles) and of the leptons
(near tri-bi-maximal mixing, thus large mixing angles). We show that such
contrasting observations can be achieved naturally via the seesaw mechanism,
whether in models with continuous or discrete family symmetries.
  We consider also in some detail the constraints on flavour changing neutral
currents arising from introducing a continuous family symmetry. We show that,
for a restricted choice of the flavon sector, continuous family symmetries are
consistent with even the most conservative limits both for the case of gauge
mediated supersymmetry breaking and the case of gravity mediated supersymmetry
breaking.


title: On positivity in T-equivariant K-theory of flag varieties

abstract:
  We prove some general results on the T-equivariant K-theory K_T(G/P) of the
flag variety G/P, where G is a semisimple complex algebraic group, P is a
parabolic subgroup and T$ is a maximal torus contained in P.
  In particular, we make a conjecture about a positivity phenomenon in K_T(G/P)
for the product of two basis elements written in terms of the basis of K_T(G/P)
given by the dual of the structure sheaf (of Schubert varieties) basis. (For
the full flag variety G/B, this dual basis is closely related to the basis
given by Kostant-Kumar.)
  This conjecture is parallel to (but different from) the conjecture of
Griffeth-Ram for the structure constants of the product in the structure sheaf
basis. We give explicit expressions for the product in the T-equivariant
K-theory of projective spaces in terms of these bases. In particular, we
establish our conjecture and the conjecture of Griffeth-Ram in this case.


title: The Elitzur-Vaidman Interaction-Free Measurements

abstract:
  The interaction-free measurements proposed by Elitzur and Vaidman (EV IFM) is
a quantum mechanical method to find an object that interacts with other systems
solely via its explosion without exploding it. In this method, an object can be
found without ``touching it'', i.e. without any particle being at its vicinity.


title: Computing L-series of hyperelliptic curves

abstract:
  We discuss the computation of coefficients of the L-series associated to a
hyperelliptic curve over Q of genus at most 3, using point counting, generic
group algorithms, and p-adic methods.


title:
AzTEC Millimetre Survey of the COSMOS Field: I. Data Reduction and
  Source Catalogue

abstract:
  We present a 1.1 mm wavelength imaging survey covering 0.3 sq. deg. in the
COSMOS field. These data, obtained with the AzTEC continuum camera on the James
Clerk Maxwell Telescope (JCMT), were centred on a prominent large-scale
structure over-density which includes a rich X-ray cluster at z = 0.73. A total
of 50 millimetre galaxy candidates, with a significance ranging from 3.5-8.5
sigma, are extracted from the central 0.15 sq. deg. area which has a uniform
sensitivity of 1.3 mJy/beam. Sixteen sources are detected with S/N > 4.5, where
the expected false-detection rate is zero, of which a surprisingly large number
(9) have intrinsic (de-boosted) fluxes > 5 mJy at 1.1 mm. Assuming the emission
is dominated by radiation from dust, heated by a massive population of young,
optically-obscured stars, then these bright AzTEC sources have FIR luminosities
> 6 x 10^12 L(sun) and star formation-rates > 1100 M(sun)/yr. Two of these nine
bright AzTEC sources are found towards the extreme peripheral region of the
X-ray cluster, whilst the remainder are distributed across the larger-scale
over-density. We describe the AzTEC data reduction pipeline, the
source-extraction algorithm, and the characterisation of the source catalogue,
including the completeness, flux de-boosting correction, false-detection rate
and the source positional uncertainty, through an extensive set of Monte-Carlo
simulations. We conclude with a preliminary comparison, via a stacked analysis,
of the overlapping MIPS 24 micron data and radio data with this AzTEC map of
the COSMOS field.


title:
Three Order Parameters in Quantum XZ Spin-Oscillator Models with
  Gibbsian Ground States

abstract:
  Quantum models on the hyper-cubic d-dimensional lattice of spin-1/2 particles
interacting with linear oscillators are shown to have three ferromagnetic
ground state order parameters. Two order parameters coincide with the
magnetization in the first and third directions and the third one is a
magnetization in a continuous oscillator variable. The proofs use a generalized
Peierls argument and two Griffiths inequalities. The class of spin-oscillator
Hamiltonians considered manifest maximal ordering in their ground states. The
models have relevance for hydrogen-bond ferroelectrics. The simplest of these
is proven to have a unique Gibbsian ground state.


title: Electric Fields in a Tokamak

abstract:
  With the establishment of vanishing net electrostatic fields in a toroidally
symmetric tokamak at equilibrium [R. W. Johnson, to appear in Phys. Rev. D],
one is left needing an explanation for the measurement of an apparent radial
electric field in experiments. Two scenarios are proposed, depending on the
type of measurement being considered. Indirect measurement via the radial
equation of motion for an impurity species possibly measures that species' net
radial viscous force, and direct measurement via the motional Stark effect
might reveal electric fields generated by the shifting of the toroidal magnetic
flux density.


title:
Gemini and Hubble Space Telescope Evidence for an Intermediate Mass
  Black Hole in omega Centauri

abstract:
  The globular cluster omega Centauri is one of the largest and most massive
members of the galactic system. However, its classification as a globular
cluster has been challenged making it a candidate for being the stripped core
of an accreted dwarf galaxy; this together with the fact that it has one of the
largest velocity dispersions for star clusters in our galaxy makes it an
interesting candidate for harboring an intermediate mass black hole. We measure
the surface brightness profile from integrated light on an HST}/ACS image of
the center, and find a central power-law cusp of logarithmic slope -0.08. We
also analyze Gemini GMOS-IFU kinematic data for a 5x5 arcsec field centered on
the nucleus of the cluster, as well as for a field 14 arcsecaway. We detect a
clear rise in the velocity dispersion from 18.6 km/s at 14 arcsec to 23 km/s in
the center. A rise in the velocity dispersion could be due to a central black
hole, a central concentration of stellar remnants, or a central orbital
structure that is radially biased. We discuss each of these possibilities. An
isotropic, spherical dynamical model implies a black hole mass of
4.0^{+0.75}_{-1.0} times 10^4 M_sun, and excludes the no black hole case at
greater than 99% significance. We have also run flattened, orbit-based models
and find similar results. While our preferred model is the existence of a
central black hole, detailed numerical simulations are required to confidently
rule out the other possibilities.


title: The AzTEC mm-Wavelength Camera

abstract:
  AzTEC is a mm-wavelength bolometric camera utilizing 144 silicon nitride
micromesh detectors. Herein we describe the AzTEC instrument architecture and
its use as an astronomical instrument. We report on several performance metrics
measured during a three month observing campaign at the James Clerk Maxwell
Telescope, and conclude with our plans for AzTEC as a facility instrument on
the Large Millimeter Telescope.


title: The nucleon magnetic moment in the epsilon-regime of HBChPT

abstract:
  The nucleon magnetic moment is calculated in the epsilon-regime of Heavy
Baryon Chiral Perturbation Theory to order epsilon^3, using the method of
collective variables to integrate nonperturbative pion zero modes.
Contributions containing multiple sources of zero modes enter, allowing for
charge-carrying zero mode pion fields that connect the sources. The result of
this calculation will allow for lattice QCD calculations involving nucleons to
systematically extract the leading low energy coefficients of Heavy Baryon
Chiral Perturbation Theory with electromagnetic interactions.


title: Black holes and universality classes of critical points

abstract:
  We argue that there exists an infinite class of conformal field theories in
diverse dimensions, having a universal ratio of the central charge c to the
normalized entropy density c'. The universality class includes all conformal
theories which possess a classical gravity dual according to the AdS/CFT
correspondence. From the practical point of view, the universality of c/c'
provides an explicit test which can be applied to determine whether a given
critical point may admit a dual description in terms of classical gravity.


title: Primordial black holes and the observed Galactic 511 keV line

abstract:
  The observed 511 keV line from the Galactic Bulge is a real challenge for
theoretical astrophysics: despite a lot of suggested mechanisms, there is still
no convincing explanation and the origin of the annihilated positrons remains
unknown. Here we discuss the possibility that a population of slowly
evaporating primordial black holes with the mass around $10^{16}-10^{17}$ g
ejects (among other particles) low--energy positrons into the Galaxy. In
addition to positrons, we have also calculated the spectrum and number density
of photons and neutrinos produced by such black holes and found that the
photons are potentially observable in the near future, while the neutrino flux
is too weak and below the terrestrial and extra--terrestrial backgrounds.
Depending on their mass distribution, such black holes could make a small
fraction or the whole cosmological dark matter.


title: Validation in Fusion Research: Towards Guidelines and Best Practices

abstract:
  Because experiment/model comparisons in magnetic confinement fusion have not
yet satisfied the requirements for validation as understood broadly, a set of
approaches to validating mathematical models and numerical algorithms are
recommended as good practices. Previously identified procedures, such as
verification, qualification, and analysis of error and uncertainty, remain
important. However, particular challenges intrinsic to fusion plasmas and
physical measurement therein lead to identification of new or less familiar
concepts that are also critical in validation. These include the primacy
hierarchy, which tracks the integration of measurable quantities, and
sensitivity analysis, which assesses how model output is apportioned to
different sources of variation. The use of validation metrics for individual
measurements is extended to multiple measurements, with provisions for the
primacy hierarchy and sensitivity. This composite validation metric is
essential for quantitatively evaluating comparisons with experiments. To mount
successful and credible validation in magnetic fusion, a new culture of
validation is envisaged.


title: Magnetic structure at zigzag edges of graphene bilayer ribbons

abstract:
  We study the edge magnetization of bilayer graphene ribbons with zigzag
edges. The presence of flat edge-state bands at the Fermi energy of undoped
bilayer, which gives rise to a strong peak in the density of states, makes
bilayer ribbons magnetic at the edges even for very small on-site electronic
repulsion. Working with the Hubbard model in the Hartree Fock approximation we
show that the magnetic structure in bilayer ribbons with zigzag edges is
ferromagnetic along the edge, involving sites of the two layers, and
antiferromagnetic between opposite edges. It is also shown that this magnetic
structure is a consequence of the nature of the edge states present in bilayer
ribbons with zigzag edges. Analogously to the monolayer case, edge site
magnetization as large as $m \approx0.2 \mu_{B}$ (per lattice site) even at
small on-site Hubbard repulsion $U \approx 0.3 {eV}$ is realized in nanometer
wide bilayer ribbons.


title:
Quantization of $r-Z$-quasi-Poisson manifolds and related modified
  classical dynamical $r$-matrices

abstract:
  Le $X$ be a $C^\infty$-manifold and $\g$ be a finite dimensional Lie algebra
acting freely on $X$. Let $r \in \ve^2(\g)$ be such that $Z=[r,r] \in
\ve^3(\g)^\g$. In this paper we prove that every quasi-Poisson
$(\g,Z)$-manifold can be quantized. This is a generalization of the existence
of a twist quantization of coboundary Lie bialgebras (\cite{EH}) in the case
$X=G$ (where $G$ is the simply connected Lie group corresponding to $\g$). We
deduce our result from a generalized formality theorem. In the case Z=0, we get
a new proof of the existence of (equivariant) formality theorem and so
(equivariant) quantization of Poisson manifold ({\it cf.} \cite{Ko,Do}). As a
consequence of our results, we get quantization of modified classical dynamical
$r$-matrices over abelian bases in the reductive case


title:
Strongly Consistent Model Order Selection for Estimating 2-D Sinusoids
  in Colored Noise

abstract:
  We consider the problem of jointly estimating the number as well as the
parameters of two-dimensional sinusoidal signals, observed in the presence of
an additive colored noise field. We begin by elaborating on the least squares
estimation of 2-D sinusoidal signals, when the assumed number of sinusoids is
incorrect. In the case where the number of sinusoidal signals is
under-estimated we show the almost sure convergence of the least squares
estimates to the parameters of the dominant sinusoids. In the case where this
number is over-estimated, the estimated parameter vector obtained by the least
squares estimator contains a sub-vector that converges almost surely to the
correct parameters of the sinusoids. Based on these results, we prove the
strong consistency of a new model order selection rule.


title: Versatile two-dimensional potentials for ultra-cold atoms

abstract:
  We propose and investigate a technique for generating smooth two-dimensional
potentials for ultra-cold atoms based on the rapid scanning of a far-detuned
laser beam using a two-dimensional acousto-optical modulator (AOM). We
demonstrate the implementation of a feed-forward mechanism for fast and
accurate control of the spatial intensity of the laser beam, resulting in
improved homogeneity for the atom trap. This technique could be used to
generate a smooth toroidal trap that would be useful for static and dynamic
experiments on superfluidity and persistent currents with ultra-cold atoms.


title:
Thermodynamic quantum crtical behavior in the anisotropic Kondo necklace
  model

abstract:
  The Ising-like anisotropy parameter $\delta$ in the Kondo necklace model is
analyzed using the bond-operator method at zero and finite temperatures for
arbitrary $d$ dimensions. A decoupling scheme on the double time Green's
functions is used to find the dispersion relation for the excitations of the
system. At zero temperature and in the paramagnetic side of the phase diagram,
we determine the spin gap exponent $\nu z\approx0.5$ in three dimensions and
anisotropy between $0\leq\delta\leq1$, a result consistent with the dynamic
exponent $z=1$ for the Gaussian character of the bond-operator treatment. At
low but finite temperatures, in the antiferromagnetic phase, the line of Neel
transitions is calculated for $\delta\ll1$ and $\delta\approx1$. For $d>2$ it
is only re-normalized by the anisotropy parameter and varies with the distance
to the quantum critical point QCP $|g|$ as, $T_N \propto |g|^{\psi}$ where the
shift exponent $\psi=1/(d-1)$. Nevertheless, in two dimensions, long range
magnetic order occurs only at T=0 for any $\delta$. In the paramagnetic phase,
we find a power law temperature dependence on the specific heat at the
\textit{quantum liquid trajectory} $J/t=(J/t)_{c}$, $T\to0$. It behaves as
$C_{V}\propto T^{d}$ for $\delta\leq 1$ and $\delta\approx1$, in concordance
with the scaling theory for $z=1$.


title: Algorithms for eps-approximations of Terrains

abstract:
  Consider a point set D with a measure function w : D -> R. Let A be the set
of subsets of D induced by containment in a shape from some geometric family
(e.g. axis-aligned rectangles, half planes, balls, k-oriented polygons). We say
a range space (D, A) has an eps-approximation P if max {R \in A} | w(R \cap
P)/w(P) - w(R \cap D)/w(D) | <= eps. We describe algorithms for
deterministically constructing discrete eps-approximations for continuous point
sets such as distributions or terrains. Furthermore, for certain families of
subsets A, such as those described by axis-aligned rectangles, we reduce the
size of the eps-approximations by almost a square root from O(1/eps^2 log
1/eps) to O(1/eps polylog 1/eps). This is often the first step in transforming
a continuous problem into a discrete one for which combinatorial techniques can
be applied. We describe applications of this result in geo-spatial analysis,
biosurveillance, and sensor networks.


title: Clifford modules and twisted K-theory

abstract:
  The purpose of this shord paper is to make the link between the fundamental
work of Atiyah, Bott and Shapiro (MR0167985/29/5250) and twisted K-theory
(MR0282363/43/8075). This link was implicit for a long time in the literature
(for the description of the real K-theory of spheres as an example) but was not
explicitly defined before.


title:
Bose-Einstein condensation in antiferromagnets close to the saturation
  field

abstract:
  At zero temperature and strong applied magnetic fields the ground sate of an
anisotropic antiferromagnet is a saturated paramagnet with fully aligned spins.
We study the quantum phase transition as the field is reduced below an upper
critical $H_{c2}$ and the system enters a XY-antiferromagnetic phase. Using a
bond operator representation we consider a model spin-1 Heisenberg
antiferromagnetic with single-ion anisotropy in hyper-cubic lattices under
strong magnetic fields. We show that the transition at $H_{c2}$ can be
interpreted as a Bose-Einstein condensation (BEC) of magnons. The theoretical
results are used to analyze our magnetization versus field data in the organic
compound $NiCl_2$-$4SC(NH_2)_2$ (DTN) at very low temperatures. This is the
ideal BEC system to study this transition since $H_{c2}$ is sufficiently low to
be reached with static magnetic fields (as opposed to pulsed fields). The
scaling of the magnetization as a function of field and temperature close to
$H_{c2}$ shows excellent agreement with the theoretical predictions. It allows
to obtain the quantum critical exponents and confirm the BEC nature of the
transition at $H_{c2}$.


title: Sums with multiplicative functions over a Beatty sequence

abstract:
  We study sums with multiplicative functions that take values over a
non-homogenous Beatty sequence. We then apply our result in a few special cases
to obtain asymptotic formulas such as the number of integers in a Beatty
sequence representable as a sum of two squares up to a given magnitude.


title: Every Minor-Closed Property of Sparse Graphs is Testable

abstract:
  Suppose $G$ is a graph with degrees bounded by $d$, and one needs to remove
more than $\epsilon n$ of its edges in order to make it planar. We show that in
this case the statistics of local neighborhoods around vertices of $G$ is far
from the statistics of local neighborhoods around vertices of any planar graph
$G'$ with the same degree bound. In fact, a similar result is proved for any
minor-closed property of bounded degree graphs.
  As an immediate corollary of the above result we infer that many well studied
graph properties, like being planar, outer-planar, series-parallel, bounded
genus, bounded tree-width and several others, are testable with a constant
number of queries, where the constant may depend on $\epsilon$ and $d$, but not
on the graph size. None of these properties was previously known to be testable
even with $o(n)$ queries.