title:
Spatial clustering in the ESO-Sculptor Survey: two-point correlation
  functions by galaxy type at redshifts 0.1 - 0.5

abstract:
  We calculate the spatial two-point auto and cross-correlation functions for
the 765 galaxies with Rc<21.5 and 0.1<z<0.51 in the ESO-Sculptor survey, and
explore the segregation effects among the populations of giant (early-type,
late spiral) and dwarf (dE, dI) galaxies. At separation of 0.3 h^-1 Mpc, pairs
of early-type galaxies dominate the clustering over all the other types of
pairs. At intermediate scales, 0.3-5 h^-1 Mpc, mixed pairs of dwarf and giant
galaxies contribute equally as pairs of giant galaxies, whereas the latter
dominate at ~10 h^-1 Mpc. We detect the signature of the transition between the
1-halo and 2-halo regimes which is expected in the scenario of galaxy formation
by hierarchical merging of dark matter halos. The early-type galaxies largely
outdo the late spiral galaxies in their 1-halo component, whereas the 2-halo
components of both giant populations are comparable. The dwarf galaxies have an
intermediate 1-halo component between the 2 giant galaxy types, and their
2-halo component is weak and consistent with null clustering. The present
analysis indicates that the early-type galaxies are preferentially located near
the centers of the most massive halos, whereas late spiral galaxies tend to
occupy their outskirts or the centers of less massive halos. This analysis also
unveils new results on the spatial distribution of dwarf galaxies: at the scale
at which they significantly cluster inside the halos (<0.3 h^-1 Mpc), they are
poorly mixed with the late spiral galaxies, and appear preferentially as
satellites of early-type galaxies.


title:
Moderate deviations and laws of the iterated logarithm for the local
  times of additive L\'{e}vy processes and additive random walks

abstract:
  We study the upper tail behaviors of the local times of the additive L\'{e}vy
processes and additive random walks. The limit forms we establish are the
moderate deviations and the laws of the iterated logarithm for the L_2-norms of
the local times and for the local times at a fixed site.


title: Anomalous distribution functions in sheared suspensions

abstract:
  We investigate velocity probability distribution functions (PDF) of sheared
hard-sphere suspensions. As observed in our Stokes flow simulations and
explained by our single-particle theory, these PDFs can show pronounced
deviations from a Maxwell-Boltzmann distribution. The PDFs are symmetric around
zero velocity and show a Gaussian core and exponential tails over more than six
orders of magnitude of probability. Following the excellent agreement of our
theory and simulation data, we demonstrate that the distribution functions
scale with the shear rate, the particle volume concentration, as well as the
fluid viscosity.


title: Radial-breathing-like phonon modes of double-walled carbon nanotubes

abstract:
  The radial-breathing-like phonon modes (RBLMs) of the double-walled carbon
nanotubes are studied in a simple analytical model, in which the interaction
force constants (FCs) can be obtained analytically from the continuous model.
The RBLMs frequencies are obtained by solving the dynamical matrix, and their
relationship with the tube radii can be obtained analytically, offering a
powerful experimental tool for determining precisely the radii of the
multi-walled carbon nanotubes.


title: Exact Hausdorff measure on the boundary of a Galton--Watson tree

abstract:
  A necessary and sufficient condition for the almost sure existence of an
absolutely continuous (with respect to the branching measure) exact Hausdorff
measure on the boundary of a Galton--Watson tree is obtained. In the case where
the absolutely continuous exact Hausdorff measure does not exist almost surely,
a criterion which classifies gauge functions $\phi$ according to whether
$\phi$-Hausdorff measure of the boundary minus a certain exceptional set is
zero or infinity is given. Important examples are discussed in four additional
theorems. In particular, Hawkes's conjecture in 1981 is solved. Problems of
determining the exact local dimension of the branching measure at a typical
point of the boundary are also solved.


title: The $\mu$-deformed Segal-Bargmann transform is a Hall type transform

abstract:
  We present an explanation of how the $\mu$-deformed Segal-Bargmann spaces,
that are studied in various articles of the author in collaboration with
Angulo, Echevarria and Pita, can be viewed as deserving their name, that is,
how they should be considered as a part of Segal-Bargmann analysis. This
explanation relates the $\mu$-deformed Segal-Bargmann transforms to the
generalized Segal-Bargmann transforms introduced by B. Hall using heat kernel
analysis. All the versions of the $\mu$-deformed Segal-Bargmann transform can
be understood as Hall type transforms. In particular, we define a
$\mu$-deformation of Hall's "Version C" generalized Segal-Bargmann transform
which is then shown to be a $\mu$-deformed convolution with a $\mu$-deformed
heat kernel followed by analytic continuation. Our results are generalizations
and analogues of the results of Hall.


title: Linear-programming Decoding of Non-binary Linear Codes

abstract:
  We develop a framework for linear-programming (LP) decoding of non-binary
linear codes over rings. We prove that the resulting LP decoder has the
`maximum likelihood certificate' property, and we show that the decoder output
is the lowest cost pseudocodeword. Equivalence between pseudocodewords of the
linear program and pseudocodewords of graph covers is proved. LP decoding
performance is illustrated for the (11,6,5) ternary Golay code with ternary PSK
modulation over AWGN, and in this case it is shown that the LP decoder
performance is comparable to codeword-error-rate-optimum hard-decision based
decoding.


title: Halo Assembly Bias in the Quasi-linear Regime

abstract:
  We address the question of whether or not assembly bias arises in the absence
of highly non-linear effects such as tidal stripping of halos near larger mass
concentrations. Therefore, we use a simplified dynamical scheme where these
effects are not modeled. We choose the punctuated Zel'dovich (PZ)
approximation, which prevents orbit mixing by coalescing particles coming
within a critical distance of each other. A numerical implementation of this
approximation is fast, allowing us to run a large number of simulations to
study assembly bias. We measure an assembly bias from 60 PZ simulations, each
with 512^3 cold particles in a 128h^-1 Mpc cubic box. The assembly bias
estimated from the correlation functions at separations < 5h^-1 Mpc for objects
(halos) at z=0 is comparable to that obtained in full N-body simulations. For
masses 4x10^11 h^-1 Mo the "oldest" 10% haloes are 3-5 times more correlated
than the "youngest" 10%. The bias weakens with increasing mass, also in
agreement with full N-body simulations. We find that that halo ages are
correlated with the dimensionality of the surrounding linear structures as
measured by the parameter (\lambda_1+\lambda_2+\lambda_3)/
(\lambda_1^2+\lambda_2^2+\lambda_3^2)^{1/2} where \lambda_i are proportional to
the eigenvalues of the velocity deformation tensor. Our results suggest that
assembly bias may already be encoded in the early stages of the evolution.


title: Quantum time uncertainty in Schwarzschild-anti-de Sitter black holes

abstract:
  The combined action of gravity and quantum mechanics gives rise to a minimum
time uncertainty in the lowest order approximation of a perturbative scheme, in
which quantum effects are regarded as corrections to the classical spacetime
geometry. From the nonperturbative point of view, both gravity and quantum
mechanics are treated on equal footing in a description that already contains
all possible backreaction effects as those above in a nonlinear manner. In this
paper, the existence or not of such minimum time uncertainty is analyzed in the
context of Schwarzschild-anti-de Sitter black holes using the isolated horizon
formalism. We show that from a perturbative point of view, a nonzero time
uncertainty is generically present owing to the energy scale introduced by the
cosmological constant, while in a quantization scheme that includes
nonperturbatively the effects of that scale, an arbitrarily high time
resolution can be reached.


title:
Anomalous heat conduction in a carbon nanowire: Molecular dynamics
  calculations

abstract:
  Heat conduction of a real quasi-one dimensional material, the finite length
carbon nanowire (CNW), inserted into the single-walled carbon nanotube (SWNT)
has been studied by the molecular dynamical (MD) method, in which both of the
longitudinal as well as transverse motions of the chain atoms in the SWNT have
been permitted. It is found that the thermal conductivity $\kappa $ of the
carbon nanowire is very high at room temperature, and diverges more likely with
the chain length logarithmically.


title: The distribution of H13CN in the circumstellar envelope around IRC+10216

abstract:
  H13CN J=8-7 sub-millimetre line emission produced in the circumstellar
envelope around the extreme carbon star IRC+10216 has been imaged at
sub-arcsecond angular resolution using the SMA. Supplemented by a detailed
excitation analysis the average fractional abundance of H13CN in the inner wind
(< 5E15 cm) is estimated to be about 4E-7, translating into a total HCN
fractional abundance of 2E-5 using the isotopic ratio 12C/13C=50.
Multi-transitional single-dish observations further requires the H13CN
fractional abundance to remain more or less constant in the envelope out to a
radius of about 4E16 cm, where the HCN molecules are effectively destroyed,
most probably, by photodissociation. The large amount of HCN present in the
inner wind provides effective line cooling that can dominate over that
generated from CO line emission. It is also shown that great care needs to be
taken in the radiative transfer modelling where non-local, and non-LTE, effects
are important and where the radiation field from thermal dust grains plays a
major role in exciting the HCN molecules. The amount of HCN present in the
circumstellar envelope around IRC+10216 is consistent with predicted
photospheric values based on equilibrium chemical models and indicates that any
non-equilibrium chemistry occurring in the extended pulsating atmosphere has no
drastic net effect on the fractional abundance of HCN molecules that enters the
outer envelope. It further suggests that few HCN molecules are incorporated
into dust grains.


title:
Stability of periodic travelling shallow-water waves determined by
  Newton's equation

abstract:
  We study the existence and stability of periodic travelling-wave solutions
for generalized Benjamin-Bona-Mahony and Camassa-Holm equations. To prove
stability, we use the abstract results of Grillakis-Shatah-Strauss and the
Floquet theory for periodic eigenvalue problems.


title: Guaranteed Accuracy for Conic Programming Problems in Vector Lattices

abstract:
  This paper presents rigorous forward error bounds for linear conic
optimization problems. The error bounds are formulated in a quite general
framework; the underlying vector spaces are not required to be
finite-dimensional, and the convex cones defining the partial ordering are not
required to be polyhedral. In the case of linear programming, second order cone
programming, and semidefinite programming specialized formulas are deduced
yielding guaranteed accuracy. All computed bounds are completely rigorous
because all rounding errors due to floating point arithmetic are taken into
account. Numerical results, applications and software for linear and
semidefinite programming problems are described.


title: Planar quark scattering at strong coupling and universality

abstract:
  We discuss scattering of fundamental matter in the planar and strong coupling
limit via the AdS/CFT correspondence, generalizing the recently proposed
calculation for adjoint matter due to Alday and Maldacena [arXiv:0705.0303].
Color decomposition of quark amplitudes is a key property allowing to repeat
the procedure in the case of fundamental matter and to derive the relation of
these strong coupling amplitudes to minimal area problems. We present the
results for two different D3-D7 systems, one is only conformal in the planar
limit and the other is exactly conformal. Our results suggest a universal
behavior of scattering amplitudes at strong coupling and planar limit (both for
gluons and quarks).


title:
Spectral properties of locally correlated electrons in a BCS
  superconductor

abstract:
  We present a detailed study of the spectral properties of a locally
correlated site embedded in a BCS superconducting medium. To this end the
Anderson impurity model with superconducting bath is analysed by numerical
renormalisation group (NRG) calculations. We calculate one and two-particle
dynamic response function to elucidate the spectral excitation and the nature
of the ground state for different parameter regimes with and without
particle-hole symmetry. The position and weight of the Andreev bound states is
given for all relevant parameters. We also present phase diagrams for the
different ground state parameter regimes. This work is also relevant for
dynamical mean field theory extensions with superconducting symmetry breaking.


title:
Detection of the Cherenkov light diffused by Sea Water with the ULTRA
  Experiment

abstract:
  The study of Ultra High Energy Cosmic Rays represents one of the most
challenging topic in the Cosmic Rays and in the Astroparticle Physics fields.
The interaction of primary particles with atmospheric nuclei produces a huge
Extensive Air Shower together with isotropic emission of UV fluorescence light
and highly directional Cherenkov photons, that are reflected/diffused
isotropically by the impact on the Earth's surface or on high optical depth
clouds. For space-based observations, detecting the reflected Cherenkov signal
in a delayed coincidence with the fluorescence light improves the accuracy of
the shower reconstruction in space and in particular the measurement of the
shower maximum, giving a strong signature for discriminating hadrons and
neutrinos, and helping to estimate the primary chemical composition. Since the
Earth's surface is mostly covered by water, the ULTRA (UV Light Transmission
and Reflection in the Atmosphere)experiment has been designed to provide the
diffusing properties of sea water, overcoming the lack of information in this
specific field. A small EAS array, made up of 5 particle detectors, and an UV
optical device, have been coupled to detect in coincidence both electromagnetic
and UV components. The detector was in operation from May to December, 2005, in
a small private harbor in Capo Granitola (Italy); the results of these
measurements in terms of diffusion coefficient and threshold energy are
presented here.


title: The mass distribution in Spiral galaxies

abstract:
  In the past years a wealth of observations has allowed us to unravel the
structural properties of the Dark and Luminous mass distribution in spirals. As
result, it has been found that their rotation curves follow, out their virial
radius, an Universal function (URC) made by two terms: one due to the
gravitational potential of a Freeman stellar disk and the other due to that of
a dark halo. The importance of the latter is found to decrease with galaxy
mass. Individual objects reveal in detail that dark halos have a density core,
whose size correlates with its central value. These properties will guide
$\Lambda$CDM Cosmology to evolve to match the challenge that observations
presently pose.


title:
A model for the study of the Shubnikov-de Haas and the integer quantum
  Hall effects in a two dimensional electronic system

abstract:
  Up to know all the experimental results concerning the integer and fractional
quantum Hall effect are related to semiconductor heterostructures (and more
recently with graphene). The common characteristic of all these systems is the
presence of a reservoir of electrons, which, in fact, in the initial stage is
the source of the electrons, providing the two-dimensional electron gas (2DES).
Then, any physical realization of a 2DES is necessarily embedded in a 3D
structure, which establishes the Fermi level. Hence, the 2DES appears to be an
open system. In this paper we present an analytical approach to the integer
quantum Hall effect (IQHE) and the Shubnikov-de Haas (SdH) phenomena in the
2DES, basing us in fundamental principles and showing the secondary role of the
localized electron states in both phenomena. In fact, we show that the IQHE is
a consequence of the fluctuations of electrons in the 2DES. Once we obtain the
density of states of the 2DES under the application of a magnetic field we
calculate both magnetoconductivities (diagonal and Hall) deducing them from the
Boltzman semiclassical equation. The model proposed reproduces both phenomena,
the width of the Hall plateaus (with the precision reached in the experimental
measurements, of the order of 10-8-10-9) and the corresponding minima of the
diagonal magnetoresistivity, and also the dependence with temperature of the
IQHE and SdH.


title:
Blocking a transition in a Free Choice net and what it tells about its
  throughput

abstract:
  In a live and bounded Free Choice Petri net, pick a non-conflicting
transition. Then there exists a unique reachable marking in which no transition
is enabled except the selected one. For a routed live and bounded Free Choice
net, this property is true for any transition of the net. Consider now a live
and bounded stochastic routed Free Choice net, and assume that the routings and
the firing times are independent and identically distributed. Using the above
results, we prove the existence of asymptotic firing throughputs for all
transitions in the net. Furthermore the vector of the throughputs at the
different transitions is explicitly computable up to a multiplicative constant.


title: Denjoy constructions for fibred homeomorphisms of the torus

abstract:
  We construct different types of quasiperiodically forced circle
homeomorphisms with transitive but non-minimal dynamics. Concerning the recent
Poincar\'e-like classification for this class of maps of Jaeger-Stark, we
demonstrate that transitive but non-minimal behaviour can occur in each of the
different cases. This closes one of the last gaps in the topological
classification. Actually, we are able to get some transitive quasiperiodically
forced circle homeomorphisms with rather complicated minimal sets. For example,
we show that, in some of the examples we construct, the unique minimal set is a
Cantor set and its intersection with each vertical fibre is uncountable and
nowhere dense (but may contain isolated points). We also prove that minimal
sets of the later kind cannot occur when the dynamics are given by the
projective action of a quasiperiodic SL(2,R)-cocycle. More precisely, we show
that, for a quasiperiodic SL(2,R)-cocycle, any minimal strict subset of the
torus either is a union of finitely many continuous curves, or contains at most
two points on generic fibres.


title:
Visible and dark matter in M 31 - II. A dynamical model and dark matter
  density distribution

abstract:
  In the present paper we derive the density distribution of dark matter (DM)
in a well-observed nearby disc galaxy, the Andromeda galaxy. From photometrical
and chemical evolution models constructed in the first part of the study (Tamm,
Tempel & Tenjes 2007 (arXiv:0707.4375), hereafter Paper I) we can calculate the
mass distribution of visible components (the bulge, the disc, the stellar halo,
the outer diffuse stellar halo). In the dynamical model we calculate stellar
rotation velocities along the major axis and velocity dispersions along the
major, minor and intermediate axes of the galaxy assuming triaxial velocity
dispersion ellipsoid. Comparing the calculated values with the collected
observational data, we find the amount of DM, which must be added to reach an
agreement with the observed rotation and dispersion data.
  We conclude that within the uncertainties, the DM distributions by Moore,
Burkert, Navarro, Frenk & White (NFW) and the Einasto fit with observations
nearly at all distances. The NFW and Einasto density distributions give the
best fit with observations.
  The total mass of M 31 with the NFW DM distribution is 1.19*10^12 M_sun, the
ratio of the DM mass to the visible mass is 10.0. For the Einasto DM
distribution, these values are 1.28*10^12 M_sun and 10.8. The ratio of the DM
mass to the visible mass inside the Holmberg radius is 1.75 for the NFW and the
Einasto distributions. For different cuspy DM distributions, the virial mass is
in a range 6.9-7.9*10^11 M_sun and the virial radius is ~150 kpc. The DM mean
densities inside 10 pc for cusped models are 33 and 16 M_sun pc^-3 for the NFW
and the Einasto profiles, respectively. For the cored Burkert profile, this
value is 0.06 M_sun pc^-3.


title: Visible and dark matter in M31 - I. Properties of stellar components

abstract:
  We construct a structural model of the Andromeda Galaxy, simultaneously
corresponding to observed photometrical and kinematical data and chemical
abundances. In this paper we present the observed surface brightness, colour
and metallicity distributions, and compare them to the model galaxy. In Paper
II (Tempel, Tamm & Tenjes 2007) we present similar data for the kinematics, and
derive the mass distribution of the galaxy. On the basis of U, B, V, R, I and L
luminosity distributions, we construct the model galaxy as a superposition of
four axially symmetric stellar components: a bulge, a disc, an inner halo and
an extended diffuse halo. By using far-infrared imaging data of M31 and a thin
dust disc assumption, we derive dust-free surface brightness and colour
distributions. We find the total absorption corrected luminosity of M31 to be
L_B = (3.3+/-0.7)x10^10 L_sun, corresponding to an absolute luminosity M_B =
-20.8+/-0.2 mag. Of the total luminosity, 41% (0.57 mag) is obscured from us by
the dust inside M31. Using chemical evolution models, we calculate
mass-to-light ratios of the components, correspoding to the colour indices and
metallicities. We find the total intrinsic mass-to-light ratio of the visible
matter to be M/L_B=3.1-5.8 M_sun/L_sun and the total mass of visible matter
M_vis =(10-19)x10^10 M_sun. The use of the model parameters for a dynamical
analysis and for determining dark matter distribution is presented in Paper II.


title:
Characteristics of the Wave Function of Coupled Oscillators in
  Semiquantum Chaos

abstract:
  Using the method of adiabatic invariants and the Born-Oppenheimer
approximation, we have successfully got the excited-state wave functions for a
pair of coupled oscillators in the so-called \textit{semiquantum chaos}. Some
interesting characteristics in the \textit{Fourier spectra} of the wave
functions and its \textit{Correlation Functions} in the regular and chaos
states have been found, which offers a new way to distinguish the regular and
chaotic states in quantum system.


title:
Fractal dimension and size scaling of domains in thin films of
  multiferroic BiFeO3

abstract:
  We have analyzed the morphology of ferroelectric domains in very thin films
of multiferroic BiFeO3. Unlike the more common stripe domains observed in
thicker films BiFeO3 or in other ferroics, the domains tend not to be straight,
but irregular in shape, with significant domain wall roughening leading to a
fractal dimensionality. Also contrary to what is usually observed in other
ferroics, the domain size appears not to scale as the square root of the film
thickness. A model is proposed in which the observed domain size as a function
of film thickness can be directly linked to the fractal dimension of the
domains.


title: Anderson Transitions

abstract:
  The physics of Anderson transitions between localized and metallic phases in
disordered systems is reviewed. The term ``Anderson transition'' is understood
in a broad sense, including both metal-insulator transitions and
quantum-Hall-type transitions between phases with localized states. The
emphasis is put on recent developments, which include: multifractality of
critical wave functions, criticality in the power-law random banded matrix
model, symmetry classification of disordered electronic systems, mechanisms of
criticality in quasi-one-dimensional and two-dimensional systems and survey of
corresponding critical theories, network models, and random Dirac Hamiltonians.
Analytical approaches are complemented by advanced numerical simulations.


title:
Runge-Lenz Vector, Accidental SU(2) Symmetry, and Unusual Multiplets for
  Motion on a Cone

abstract:
  We consider a particle moving on a cone and bound to its tip by $1/r$ or
harmonic oscillator potentials. When the deficit angle of the cone divided by
$2 \pi$ is a rational number, all bound classical orbits are closed.
Correspondingly, the quantum system has accidental degeneracies in the discrete
energy spectrum. An accidental SU(2) symmetry is generated by the rotations
around the tip of the cone as well as by a Runge-Lenz vector. Remarkably, some
of the corresponding multiplets have fractional ``spin'' and unusual
degeneracies.


title:
Nuclear matter with three-body forces from self-consistent spectral
  calculations

abstract:
  We calculate the equation of state of nuclear matter in the self-consistent
T-matrix scheme including three-body nuclear interactions. We study the effect
of the three-body force on the self-energies and spectral functions of nucleons
in medium.


title:
Electron-Positron Pair Loading and the Origin of the Upstream Magnetic
  Field in GRB Shocks

abstract:
  We investigate here the effects of plasma instabilities driven by rapid
electron/positron pair cascades, which arise in the environment of GRB sources
as a result of back-scattering of a seed fraction of the original spectrum. The
injection of electron/positron pairs induces strong streaming motions in the
ambient medium. One therefore expects the pair-enriched medium ahead of the
forward shock to be strongly sheared on length scales comparable to the
radiation front thickness. Using three-dimensional particle-in-cell
simulations, we show that plasma instabilities driven by these streaming
electron/positron pairs are responsible for the excitation of
near-equipartition, turbulent magnetic fields. Our results reveal the
importance of the electromagnetic filamentation instability in ensuring an
effective coupling between electron/positron pairs and ions, and may help
explain the origin of large upstream fields in GRB shocks.


title:
On the Hamiltonian structure of Hirota-Kimura discretization of the
  Euler top

abstract:
  This paper deals with a remarkable integrable discretization of the so(3)
Euler top introduced by Hirota and Kimura. Such a discretization leads to an
explicit map, whose integrability has been understood by finding two
independent integrals of motion and a solution in terms of elliptic functions.
Our goal is the construction of its Hamiltonian formulation. After giving a
simplified and streamlined presentation of their results, we provide a
bi-Hamiltonian structure for this discretization, thus proving its
integrability in the standard Liouville-Arnold sense.


title:
Quantum rotor description of the Mott-insulator transition in the
  Bose-Hubbard model

abstract:
  We present the novel approach to the Bose-Hubbard model using the
$\mathrm{U}(1)$ quantum rotor description. The effective action formalism
allows us to formulate a problem in the phase only action and obtain an
analytical formulas for the critical lines. We show that the nontrivial
$\mathrm{U}(1)$ phase field configurations have an impact on the phase
diagrams. The topological character of the quantum field is governed by terms
of the integer charges - winding numbers. The comparison presented results to
recently obtained quantum Monte Carlo numerical calculations suggests that the
competition between quantum effects in strongly interacting boson systems is
correctly captured by our model.


title: Density Matrix Renormalization for Model Reduction in Nonlinear Dynamics

abstract:
  We present a novel approach for model reduction of nonlinear dynamical
systems based on proper orthogonal decomposition (POD). Our method, derived
from Density Matrix Renormalization Group (DMRG), provides a significant
reduction in computational effort for the calculation of the reduced system,
compared to a POD. The efficiency of the algorithm is tested on the one
dimensional Burgers equations and a one dimensional equation of the Fisher type
as nonlinear model systems.


title:
Plurisubharmonic functions on the octonionic plane and Spin(9)-invariant
  valuations on convex sets

abstract:
  A new class of plurisubharmonic functions on the octonionic plane O^2= R^{16}
is introduced. An octonionic version of theorems of A.D. Aleksandrov and Chern-
Levine-Nirenberg, and Blocki are proved. These results are used to construct
new examples of continuous translation invariant valuations on convex subsets
of O^2=R^{16}. In particular a new example of Spin(9)-invariant valuation on
R^{16} is given.


title: Nonlinear Dirac equations on Riemann surfaces

abstract:
  We develop analytical methods for nonlinear Dirac equations. Examples of such
equations include Dirac-harmonic maps with curvature term and the equations
describing the generalized Weierstrass representation of surfaces in
three-manifolds. We provide the key analytical steps, i.e., small energy
regularity and removable singularity theorems and energy identities for
solutions.


title:
Backward stochastic differential equations with random stopping time and
  singular final condition

abstract:
  In this paper we are concerned with one-dimensional backward stochastic
differential equations (BSDE in short) of the following type: \[Y_t=\xi
-\int_{t\wedge \tau}^{\tau}Y_r|Y_r|^q dr-\int_{t\wedge \tau}^{\tau}Z_r
dB_r,\qquad t\geq 0,\] where $\tau$ is a stopping time, $q$ is a positive
constant and $\xi$ is a $\mathcal{F}_{\tau}$-measurable random variable such
that $\mathbf{P}(\xi =+\infty)>0$. We study the link between these BSDE and the
Dirichlet problem on a domain $D\subset \mathbb{R}^d$ and with boundary
condition $g$, with $g=+\infty$ on a set of positive Lebesgue measure. We also
extend our results for more general BSDE.


title: Direct observation of oxygen superstructures in manganites

abstract:
  We report the observation of superstructures associated with the oxygen
2p-states in two prototypical manganites using x-ray diffraction at the oxygen
K-edge. We determine the nature of the orderings and discuss our picture with
respect to novel theoretical models. In the stripe order system Bi0.31 Ca0.69
MnO3, hole-doped O states are found to be orbitally ordered, at the same
propagation vector as the Mn orbital ordering, but no evidence is found to
support a picture of oxygen charge stripes at this periodicity. In La 7/8 Sr
1/8 MnO3, we observe a 2p charge ordering described by alternating hole-poor
and hole-rich MnO planes that is consistent with recent predictions.


title: Separation Logic for Small-step Cminor

abstract:
  Cminor is a mid-level imperative programming language; there are
proved-correct optimizing compilers from C to Cminor and from Cminor to machine
language. We have redesigned Cminor so that it is suitable for Hoare Logic
reasoning and we have designed a Separation Logic for Cminor. In this paper, we
give a small-step semantics (instead of the big-step of the proved-correct
compiler) that is motivated by the need to support future concurrent
extensions. We detail a machine-checked proof of soundness of our Separation
Logic. This is the first large-scale machine-checked proof of a Separation
Logic w.r.t. a small-step semantics. The work presented in this paper has been
carried out in the Coq proof assistant. It is a first step towards an
environment in which concurrent Cminor programs can be verified using
Separation Logic and also compiled by a proved-correct compiler with formal
end-to-end correctness guarantees.


title:
Control of the Casimir force by the modification of dielectric
  properties with light

abstract:
  The experimental demonstration of the modification of the Casimir force
between a gold coated sphere and a single-crystal Si membrane by light pulses
is performed. The specially designed and fabricated Si membrane was irradiated
with 514 nm laser pulses of 5 ms width in high vacuum leading to a change of
the charge-carrier density. The difference in the Casimir force in the presence
and in the absence of laser radiation was measured by means of an atomic force
microscope as a function of separation at different powers of the absorbed
light. The total experimental error of the measured force differences at a
separation of 100 nm varies from 10 to 20% in different measurements. The
experimental results are compared with theoretical computations using the
Lifshitz theory at both zero and laboratory temperatures. The total theoretical
error determined mostly by the uncertainty in the concentration of charge
carriers when the light is incident is found to be about 14% at separations
less than 140 nm. The experimental data are consistent with the Lifshitz theory
at laboratory temperature, if the static dielectric permittivity of
high-resistivity Si in the absence of light is assumed to be finite. If the dc
conductivity of high-resistivity Si in the absence of light is included into
the model of dielectric response, the Lifshitz theory at nonzero temperature is
shown to be experimentally inconsistent at 95% confidence. The demonstrated
phenomenon of the modification of the Casimir force through a change of the
charge-carrier density is topical for applications of the Lifshitz theory to
real materials in fields ranging from nanotechnology and condensed matter
physics to the theory of fundamental interactions.


title:
A three-dimensional multidimensional gas-kinetic scheme for the
  Navier-Stokes equations under gravitational fields

abstract:
  This paper extends the gas-kinetic scheme for one-dimensional inviscid
shallow water equations (J. Comput. Phys. 178 (2002), pp. 533-562) to
multidimensional gas dynamic equations under gravitational fields. Four
important issues in the construction of a well-balanced scheme for gas dynamic
equations are addressed. First, the inclusion of the gravitational source term
into the flux function is necessary. Second, to achieve second-order accuracy
of a well-balanced scheme, the Chapman-Enskog expansion of the Boltzmann
equation with the inclusion of the external force term is used. Third, to avoid
artificial heating in an isolated system under a gravitational field, the
source term treatment inside each cell has to be evaluated consistently with
the flux evaluation at the cell interface. Fourth, the multidimensional
approach with the inclusion of tangential gradients in two-dimensional and
three-dimensional cases becomes important in order to maintain the accuracy of
the scheme. Many numerical examples are used to validate the above issues,
which include the comparison between the solutions from the current scheme and
the Strang splitting method. The methodology developed in this paper can also
be applied to other systems, such as semi-conductor device simulations under
electric fields.


title:
Effective low-dimensional Hamiltonian for strongly interacting atoms in
  a transverse trap

abstract:
  We derive an effective low-dimensional Hamiltonian for strongly interacting
ultracold atoms in a transverse trapping potential near a wide Feshbach
resonance. The Hamiltonian includes crucial information about transverse
excitations in an effective model with renormalized interaction between atoms
and composite dressed molecules. We fix all the parameters in the Hamiltonian
for both one- and two-dimensional cases.


title:
Reversibility, heat dissipation and the importance of the thermal
  environment in stochastic models of nonequilibrium steady states

abstract:
  We examine stochastic processes that are used to model nonequilibrium
processes (e.g, pulling RNA or dragging colloids) and so deliberately violate
detailed balance. We argue that by combining an information-theoretic measure
of irreversibility with nonequilibrium work theorems, the thermal physics
implied by abstract dynamics can be determined. This measure is bounded above
by thermodynamic entropy production and so may quantify how well a stochastic
dynamics models reality. We also use our findings to critique various modeling
approaches and notions arising in steady-state thermodynamics.


title:
Systematic errors in Gaussian Quantum Monte Carlo and a systematic study
  of the symmetry projection method

abstract:
  Gaussian Quantum Monte Carlo (GQMC) is a stochastic phase space method for
fermions with positive weights. In the example of the Hubbard model close to
half filling it fails to reproduce all the symmetries of the ground state
leading to systematic errors at low temperatures. In a previous work [Phys.
Rev. B {\bf 72}, 224518 (2005)] we proposed to restore the broken symmetries by
projecting the density matrix obtained from the simulation onto the ground
state symmetry sector. For ground state properties, the accuracy of this method
depends on a {\it large overlap} between the GQMC and exact density matrices.
Thus, the method is not rigorously exact. We present the limits of the approach
by a systematic study of the method for 2 and 3 leg Hubbard ladders for
different fillings and on-site repulsion strengths. We show several indications
that the systematic errors stem from non-vanishing boundary terms in the
partial integration step in the derivation of the Fokker-Planck equation.
Checking for spiking trajectories and slow decaying probability distributions
provides an important test of the reliability of the results. Possible
solutions to avoid boundary terms are discussed. Furthermore we compare results
obtained from two different sampling methods: Reconfiguration of walkers and
the Metropolis algorithm.


title:
Resonance phenomena in asymmetric superconducting quantum interference
  devices

abstract:
  Theory of self induced resonances in asymmetric two-junction interferometer
device is presented. In real devices it is impossible to have an ideal
interferometer free of imperfections. Thus, we extended previous theoretical
approaches introducing a model which contains several asymmetries: Josephson
current $\epsilon$, capacitances $\chi$ and dissipation $\rho$ presented in an
equivalent circuit. Moreover, non conventional symmetry of the order parameter
in high temperature superconducting quantum interference devices forced us to
include phase asymmetries. Therefore, the model has been extended to the case
of $\pi$-shift interferometers, where a phase shift is present in one of the
junctions.


title:
La $\mathrm{Z}_l$-cohomologie du mod\`ele de Deligne-Carayol est sans
  torsion

abstract:
  This article is the $\mathrm{Z}_l$-version of my paper "Monodromie du
faisceau pervers des cycles \'evanescents de quelques vari\'et\'es de Shimura
simples" in Invent. Math. 2009 vol 177 pp. 239-280, where we study the
vanishing cycles of some unitary Shimura variety. The aim is to prove that the
cohomology sheaves of this complexe are free so that, thanks to the main
theorem of Berkovich on vanishing cycles, we can deduce that the
$\mathrm{Z}_l$-cohomology of the model of Deligne-Carayol is free. There will
be a second article which will be the $\mathrm{Z}_l$ version of my paper
"Conjecture de monodromie-poids pour quelques vari\'t\'es de Shimura unitaires"
in Compositio vol 146 part 2, pp. 367-403. The aim of this second article will
be to study the torsion of the cohomology groups of these Shimura varieties.


title:
Ultracold collisions in magnetic fields: reducing inelastic cross
  sections near Feshbach resonances

abstract:
  We have carried out bound-state and low-energy quantum scattering
calculations on He + NH (triplet Sigma) in magnetic fields, with the NH
molecule in its n=1 rotationally excited states. We have explored the pattern
of levels as a function of magnetic field and identified the nearly good
quantum numbers in different regimes. We have used the bound-state calculations
to locate low-energy Feshbach resonances. When the magnetic field is used to
tune across such a resonance, the real and imaginary part of the scattering
length show asymmetric oscillations and peaks with amplitude between 1 and 3
Angstroms. The scattering length does not pass through a pole at resonance. The
resonant behavior is characterized by a complex resonant scattering length
a_res. The corresponding inelastic cross sections show troughs as well as peaks
near resonance. This may be important for efforts to achieve evaporative and
sympathetic cooling for molecules, because it offers the hope that inelastic
trap losses can be reduced by tuning close to a Feshbach resonance.


title: Pure state estimation and the characterization of entanglement

abstract:
  A connection between the state estimation problem and the separability
problem is noticed and exploited to find efficient numerical algorithms to
solve the first one. Based on these ideas, we also derive a systematic method
to obtain upper bounds on the maximum local fidelity when the states are
distributed among several distant parties.


title: Enumerating the Saneblidze-Umble diagonal terms

abstract:
  The author presents a computer implementation, calculating the terms of the
Saneblidze-Umble diagonals on the permutahedron and the associahedron. The code
is analyzed for correctness and presented in the paper, the source code of
which simultaneously represents both the paper and the program.


title: Orbital structure in N-Body models of barred galaxies

abstract:
  We study the orbital structure of a self-consistent N-body equilibrium
configuration of a barred galaxy constructed from cosmological initial
conditions. The value of its spin parameter L is near the observed value of our
Galaxy L=0.22. We classify the orbits in regular and chaotic using a
combination of two different methods and find 60% of them to be chaotic. We
examine the phase space using projections of the 4D surfaces of section for
test particles as well as for real N-body particles. The real particles are not
uniformly distributed in the whole phase space but they avoid orbits that do
not support the bar. We use frequency analysis for the regular orbits as well
as for the chaotic ones to classify certain types of orbits of our
self-consistent system. We find the main resonant orbits and their statistical
weight in supporting the shape of the bar and we emphasize the role of weakly
chaotic orbits in supporting the boxiness at the end of the bar.


title: Entanglement measures: state ordering vs local operations

abstract:
  A set of all states of a bi-partite quantum system can be divided into
subsets each of which contains states with the same degree of entanglement. In
this paper we address a question whether local operations (without classical
communication) affect the entanglement-induced state ordering. We show that
arbitrary unilocal channel (i.e., a channel that acts on one sub-system of a
bi-partite system only) might change the ordering for an arbitrary nontrivial
measure of entanglement. A slightly weaker result holds for the maximally
entangled states. In particular, the maximally entangled states might not
remain the most entangled ones at the output of a unilocal noise channel.


title: MSSM Effects in Top-antitop Production at the LHC

abstract:
  We report on a calculation of the effects of supersymmetry on the
cross-section for top-antitop production at LHC. A numerical study is carried
out for the ten benchmarks of the Snowmass accord. It is found that the higher
order effects involving supersymmetric particles in internal loops can be as
high as 6%, both for the cross-section and the (parity even) helicity
asymmetry, for one particular benchmark. For other benchmarks smaller but
nonetheless observable corrections are found.


title: Empirical constraints on vacuum decay in the stringy landscape

abstract:
  It is generally considered as self evident that the lifetime of our vacuum in
the landscape of string theory cannot be much shorter than the current age of
the universe. Here I show why this lower limit is invalid. A certain type of
``parallel universes'' is a necessary consequence of the string-landscape
dynamics and might well allow us to ``survive'' vacuum decay. As a consequence
our stringy vacuum's lifetime is empirically unconstrained and could be very
short. Based on this counter-intuitive insight I propose a novel type of
laboratory experiment that searches for an apparent violation of the
quantum-mechanical Born rule by gravitational effects on vacuum decay. If the
lifetime of our vacuum should turn out to be shorter than 6 x 10^{-13} seconds
such an experiment is sufficiently sensitive to determine its value with
state-of-the-art equipment.


title: Giant resonances of endohedral atoms

abstract:
  We demonstrate for the first time that the effect of fullerene shell upon
photoionization of the "caged" atom in an endohedral can result in formation of
Giant Endohedral Resonances or GER. This is illustrated by the concrete case of
Xe@C60 photoionization cross-section that exhibits at 17 eV a powerful
resonance with total oscillator strengths of about 25. The prominent
modification of the 5p6 electron photoionization cross-section of Xe@C60 takes
place due to strong fullerene shell polarization under the action of the
incoming electromagnetic wave and oscillation of this cross-section due to the
reflection of the photoelectron from Xe by the C60. These two factors transform
the smoothly decreasing 5p6 cross-section of Xe into a rather complex curve
with a powerful maximum for Xe@C60, with the oscillator strength being equal to
25! We present also the results for the dipole angular anisotropy parameter
that is strongly affected by the reflection of the photoelectron waves but not
modified by C60 polarization. The polarization of C60 is expressed via its
total photoabsorption cross-section. The reflection of the photoelectron is
taken into account in the frame of the so-called bubble potential that is a
spherical delta-type potential.


title:
Bulk Viscosity driven clusterization of quark-gluon plasma and early
  freeze-out in relativistic heavy-ion collisions

abstract:
  We introduce a new scenario for heavy ion collisions that could solve the
lingering problems associated with the so-called HBT puzzle. We postulate that
the system starts expansion as the perfect quark-gluon fluid but close to
freeze-out it splits into clusters, due to a sharp rise of bulk viscosity in
the vicinity of the hadronization transition. We then argue that the
characteristic cluster size is determined by the viscosity coefficient and the
expansion rate. Typically it is much smaller and independent of the total
system volume. These clusters maintain the pre-existing outward-going flow, as
a spray of droplets, but develop no flow of their own, and hadronize by
evaporation. We provide an ansatz for converting the hydrodynamic output into
clusters.


title:
Dirac-fermions and conductance-oscillations in (s,d)-wave
  superconductor/normal graphene junctions

abstract:
  We investigate quantum transport in a normal/superconductor graphene
heterostructure, including the possibility of an anisotropic pairing potential
in the superconducting region. We find that under certain circumstances, the
conductance displays an undamped, oscillatory behaviour as a function of
applied bias voltage. Also, we investigate how the conductance spectra are
affected by a d-wave pairing symmetry. These results combine unusual features
of the electronic structure of graphene with the unconventional pairing
symmetry found for instance in high-T_c superconductors.


title:
Relativistic nature of a magnetoelectric modulus of Cr_2O_3-crystals: a
  new 4-dimensional pseudoscalar and its measurement

abstract:
  Earlier, the magnetoelectric effect of chromium sesquioxide Cr_2O_3 has been
determined experimentally as a function of temperature. One measures the
electric field-induced magnetization on Cr_2O_3 crystals or the magnetic
field-induced polarization. From the magnetoelectric moduli of Cr_2O_3 we
extract a 4-dimensional relativistic invariant pseudoscalar
$\widetilde{\alpha}$. It is temperature dependent and of the order of
10^{-4}/Z_0, with Z_0 as vacuum impedance. We show that the new pseudoscalar is
odd under parity transformation and odd under time inversion. Moreover,
$\widetilde{\alpha}$ is for Cr_2O_3 what Tellegen's gyrator is for two port
theory, the axion field for axion electrodynamics, and the PEMC (perfect
electromagnetic conductor) for electrical engineering.


title:
Backlund Transformations and Darboux Integrability for Nonlinear Wave
  Equations

abstract:
  We prove that second-order hyperbolic Monge-Ampere equations for one function
of two variables are connected to the wave equation by a Backlund
transformation if and only if they are integrable by the method of Darboux at
second order. One direction of proof, proving Darboux integrability, follows
the implications of the wave equation for the invariants of the G-structure
associated to the Backlund transformation. The other direction constructs
Backlund transformations for Darboux integrable equations as solutions of an
involutive exterior differential system. Explicit transformations are given for
several equations on the Goursat-Vessiot list of Darboux-integrable equations.


title:
Time-resolved refractive index and absorption mapping of light-plasma
  filaments in water

abstract:
  By means of a quantitative shadowgraphic method, we performed a space-time
characterization of the refractive index variation and transient absorption
induced by a light-plasma filament generated by a 100 fs laser pulse in water.
The formation and evolution of the plasma channel in the proximity of the
nonlinear focus were observed with a 23 fs time resolution.


title:
On the role of twisted statistics in the noncommutative degenerate
  electron gas

abstract:
  We consider the problem of a degenerate electron gas in the background of a
uniformly distributed positive charge, ensuring overall neutrality of the
system, in the presence of non-commutativity. In contrast to previous
calculations that did not include twisted statistics, we find corrections to
the ground state energy already at first order in perturbation theory when the
twisted statistics is taken into account. These corrections arise since the
interaction energy is sensitive to two particle correlations, which are
modified for twisted anti-commutation relations.


title: Intrinsic tunneling in phase separated manganites

abstract:
  We present evidence of direct electron tunneling across intrinsic insulating
regions in sub-micrometer wide bridges of the phase separated ferromagnet
(La,Pr,Ca)MnO$_3$. Upon cooling below the Curie temperature, a predominantly
ferromagnetic supercooled state persists where tunneling across the intrinsic
tunnel barriers (ITBs) results in metastable, temperature-independent,
high-resistance plateaus over a large range of temperatures. Upon application
of a magnetic field, our data reveal that the ITBs are extinguished resulting
in sharp, colossal, low-field resistance drops. Our results compare well to
theoretical predictions of magnetic domain walls coinciding with the intrinsic
insulating phase.


title:
Measurement of the $\vec{\gamma} p \to K^+ \Lambda$ Reaction at Backward
  Angles

abstract:
  Cross sections for the $\gamma p \to K^+ \Lambda$ have been measured at
backward angles using linearly polarized photons in the range 1.50 to 2.37 GeV.
In addition, the beam asymmetry for this reaction has been measured for the
first time at backward angles. The $\Lambda$ was detected at forward angles in
the LEPS spectrometer via its decay to $p\pi^-$ and the K^+ was inferred using
the technique of missing mass. These measurements, corresponding to kaons at
far backward angles in the center-of-mass frame, complement similar CLAS data
at other angles. Comparison with theoretical models shows that the reactions in
these kinematics provide further opportunities to investigate the reaction
mechanisms of hadron dynamics.


title:
Josephson effect in thin-film superconductor/insulator/superconductor
  junctions with misaligned in-plane magnetic fields

abstract:
  We study a tunnel junction consisting of two thin-film s-wave superconductors
separated by a thin, insulating barrier in the presence of misaligned in-plane
exchange fields. We find an interesting interplay between the superconducting
phase difference and the relative orientation of the exchange fields,
manifested in the Josephson current across the junction. Specifically, this may
be written $I_\text{J}^\text{C} = (I_0+I_m ~ \cos\phi) \sin\Delta\theta$, where
I_0 and I_m are constants, and $\phi$ is the relative orientation of the
exchange fields while $\Delta\theta$ is the superconducting phase difference.
Similar results have recently been obtained in other S/I/S junctions coexisting
with helimagnetic or ferromagnetic order. We calculate the superconducting
order parameter self-consistently, and investigate quantitatively the effect
which the misaligned exchange fields constitute on the Josephson current, to
see if I_m may have an appreciable effect on the Josephson current. It is found
that I_0 and I_m become comparable in magnitude at sufficiently low
temperatures and fields close to the critical value, in agreement with previous
work. From our analytical results, it then follows that the Josephson current
in the present system may be controlled in a well-defined manner by a rotation
of the exchange fields on both sides of the junction. We discuss a possible
experimental realization of this proposition.


title: On Shokurov-type b-divisorial algebras of higher rank

abstract:
  The purpose of this paper is to lay the foundations for the theory of higher
rank b-divisorial algebras of Shokurov type. We develop techniques to deal with
such objects and propose two natural conjectures regarding Shokurov algebras
and adjoint algebras. We confirm these conjectures in the case of affine
curves.


title:
Relative abundances of cosmic ray nuclei B-C-N-O in the energy region
  from 10 GeV/n to 300 GeV/n. Results from ATIC-2 (the science flight of ATIC)

abstract:
  The ATIC balloon-borne experiment measures the energy spectra of elements
from H to Fe in primary cosmic rays from about 100 GeV to 100 TeV. ATIC is
comprised of a fully active bismuth germanate calorimeter, a carbon target with
embedded scintillator hodoscopes, and a silicon matrix that is used as the main
charge detector. The silicon matrix produces good charge resolution for protons
and helium but only partial resolution for heavier nuclei. In the present
paper, the charge resolution of ATIC was improved and backgrounds were reduced
in the region from Be to Si by using the upper layer of the scintillator
hodoscope as an additional charge detector. The flux ratios of nuclei B/C, C/O,
N/O in the energy region from about 10 GeV/nucleon to 300 GeV/nucleon obtained
from this high-resolution, high-quality charge spectra are presented, and
compared with existing theoretical predictions.


title: Consensus formation on adaptive networks

abstract:
  The structure of a network can significantly influence the properties of the
dynamical processes which take place on them. While many studies have been
devoted to this influence, much less attention has been devoted to the
interplay and feedback mechanisms between dynamical processes and network
topology on adaptive networks. Adaptive rewiring of links can happen in real
life systems such as acquaintance networks where people are more likely to
maintain a social connection if their views and values are similar. In our
study, we consider different variants of a model for consensus formation. Our
investigations reveal that the adaptation of the network topology fosters
cluster formation by enhancing communication between agents of similar opinion,
though it also promotes the division of these clusters. The temporal behavior
is also strongly affected by adaptivity: while, on static networks, it is
influenced by percolation properties, on adaptive networks, both the early and
late time evolution of the system are determined by the rewiring process. The
investigation of a variant of the model reveals that the scenarios of
transitions between consensus and polarized states are more robust on adaptive
networks.


title: HiRes Estimates and Limits for Neutrino Fluxes at the Highest Energies

abstract:
  The High Resolution Fly's Eye Experiment (HiRes) measures cosmic rays (CR) at
the highest energies using the air fluorescence technique. As data taking on
the Dugway Proving Grounds in Western Utah is finished, the HiRes data are
relevant for cosmogenic neutrinos in two different ways. We first use our best
fit to the measured HiRes CR spectrum together with a model of the
extragalactic CR sources to derive the expected cosmogenic neutrino and gamma
ray fluxes at Earth. We then use the HiRes data directly to set competitive
experimental limits on the electron and tau neutrino fluxes at the highest
energies.


title:
Transient termination of synaptically sustained spiking by stochastic
  inputs in a pair of coupled Type 1 neurons

abstract:
  We examine the effects of stochastic input currents on the firing behavior of
two excitable neurons coupled with fast excitatory synapses. In such cells
(models), typified by the quadratic integrate and fire model, mutual synaptic
coupling can cause sustained firing or oscillatory behavior which is
necessarily antiphase. Additive Gaussian white noise can transiently terminate
the oscillations, hence destroying the stable limit cycle. Further application
of the noise may return the system to spiking activity. In a particular noise
range, the transition times between the oscillating and the resting state are
strongly asymmetric. We numerically investigate an approximate basin of
attraction, A, of the periodic orbit and use Markov process theory to explain
the firing behavior in terms of the probability of escape of trajectories from
A


title:
OVRO N2H+ Observations of Class 0 Protostars: Constraints on the
  Formation of Binary Stars

abstract:
  We present the results of an interferometric study of the N2H+(1--0) emission
from nine nearby, isolated, low-mass protostellar cores, using the OVRO
millimeter array. The main goal of this study is the kinematic characterization
of the cores in terms of rotation, turbulence, and fragmentation. Eight of the
nine objects have compact N2H+ cores with FWHM radii of 1200 -- 3500 AU,
spatially coinciding with the thermal dust continuum emission. The only more
evolved (Class I) object in the sample (CB 188) shows only faint and extended
N2H+ emission. The mean N2H+ line width was found to be 0.37 km/s. Estimated
virial masses range from 0.3 to 1.2 M_sun. We find that thermal and turbulent
energy support are about equally important in these cores, while rotational
support is negligible. The measured velocity gradients across the cores range
from 6 to 24 km/s/pc. Assuming these gradients are produced by bulk rotation,
we find that the specific angular momenta of the observed Class 0 protostellar
cores are intermediate between those of dense (prestellar) molecular cloud
cores and the orbital angular momenta of wide PMS binary systems. There appears
to be no evolution (decrease) of angular momentum from the smallest prestellar
cores via protostellar cores to wide PMS binary systems. In the context that
most protostellar cores are assumed to fragment and form binary stars, this
means that most of the angular momentum contained in the collapse region is
transformed into orbital angular momentum of the resulting stellar binary
systems.


title:
On the smoothness of static multi-black hole solutions of
  higher-dimensional Einstein-Maxwell theory

abstract:
  Previous work has shown that static multi-black hole solutions of
higher-dimensional Einstein-Maxwell theory do not possess smooth horizons. We
show that the lack of smoothness is worse than previously demonstrated. We
consider solutions describing multiple black holes on a common axis. In five
dimensions, the metric is generically twice, but not three times, continuously
differentiable at the horizon. The Maxwell field is generically continuous, but
not differentiable, at the horizon. In more than five dimensions, the metric is
once, but not twice, continuously differentiable, and there is a
parallely-propagated curvature singularity at the horizon. The Maxwell field
strength is again continuous, but not differentiable, at the horizon.


title: Spicule emission profiles observed in \ion{He}{i} 10830 \AA

abstract:
  Off-the-limb observations with high spatial and spectral resolution will help
us understand the physical properties of spicules in the solar chromosphere
Spectropolarimetric observations of spicules in the \ion{He}{i} 10830 \AA\
multiplet were obtained with the Tenerife Infrared Polarimeter on the German
Vacuum Tower Telescope at the Observatorio del Teide (Tenerife, Spain). The
analysis shows the variation of the off-limb emission profiles as a function of
the distance to the visible solar limb. The ratio between the intensities of
the blue and the red components of this triplet $({\cal R}=I_{\rm blue}/I_{\rm
red})$ is an observational signature of the optical thickness along the light
path, which is related to the intensity of the coronal irradiation. We present
observations of the intensity profiles of spicules above a quiet Sun region.
The observable ${\cal R}$ as a function of the distance to the visible limb is
also given. We have compared our observational results to the intensity ratio
obtained from detailed radiative transfer calculations in semi-empirical models
of the solar atmosphere assuming spherical geometry. The agreement is purely
qualitative. We argue that future models of the solar chromosphere and
transition region should account for the observational constraints presented
here.


title:
Specific heat of a one-dimensional interacting Fermi system: the role of
  anomalies

abstract:
  We re-visit the issue of the temperature dependence of the specific heat C(T)
for interacting fermions in 1D. The charge component C_c(T) scales linearly
with T, but the spin component C_s (T) displays a more complex behavior with T
as it depends on the backscattering amplitude, g_1, which scales down under RG
transformation and eventually behaves as g_1 (T) \sim 1/\log T. We show,
however, by direct perturbative calculations that C_s(T) is strictly linear in
T to order g^2_1 as it contains the renormalized backscattering amplitude not
on the scale of T, but at the cutoff scale set by the momentum dependence of
the interaction around 2k_F. The running amplitude g_1 (T) appears only at
third order and gives rise to an extra T/\log^3 T term in C_s (T). This agrees
with the results obtained by a variety of bosonization techniques. We also show
how to obtain the same expansion in g_1 within the sine-Gordon model.


title:
Apoastron Shift Constraints on Dark Matter Distribution at the Galactic
  Center

abstract:
  The existence of dark matter (DM) at scales of few pc down to $\simeq
10^{-5}$ pc around the centers of galaxies and in particular in the Galactic
Center region has been considered in the literature. Under the assumption that
such a DM clump, principally constituted by non-baryonic matter (like WIMPs)
does exist at the center of our galaxy, the study of the $\gamma$-ray emission
from the Galactic Center region allows us to constrain both the mass and the
size of this DM sphere. Further constraints on the DM distribution parameters
may be derived by observations of bright infrared stars around the Galactic
Center. Hall and Gondolo \cite{hallgondolo} used estimates of the enclosed mass
obtained in various ways and tabulated by Ghez et al.
\cite{Ghez_2003,Ghez_2005}. Moreover, if a DM cusp does exist around the
Galactic Center it could modify the trajectories of stars moving around it in a
sensible way depending on the DM mass distribution. Here, we discuss the
constraints that can be obtained with the orbit analysis of stars (as S2 and
S16) moving inside the DM concentration with present and next generations of
large telescopes. In particular, consideration of the S2 star apoastron shift
may allow improving limits on the DM mass and size.


title:
Elliptic Flow, Initial Eccentricity and Elliptic Flow fluctuations in
  Heavy Ion Collisions at RHIC

abstract:
  We present measurements of elliptic flow and event-by-event fluctuations
established by the PHOBOS experiment. Elliptic flow scaled by participant
eccentricity is found to be similar for both systems when collisions with the
same number of participants or the same particle area density are compared. The
agreement of elliptic flow between Au+Au and Cu+Cu collisions provides evidence
that the matter is created in the initial stage of relativistic heavy ion
collisions with transverse granularity similar to that of the participant
nucleons. The event-by-event fluctuation results reveal that the initial
collision geometry is translated into the final state azimuthal particle
distribution, leading to an event-by-event proportionality between the observed
elliptic flow and initial eccentricity.


title:
On the Hawking radiation as tunneling for a class of dynamical black
  holes

abstract:
  The instability against emission of massless particles by the trapping
horizon of an evolving black hole is analyzed with the use of the
Hamilton-Jacobi method. The method automatically selects one special expression
for the surface gravity of a changing horizon. Indeed, the strength of the
horizon singularity turns out to be governed by the surface gravity as was
defined a decade ago by Hayward using Kodama's theory of spherically symmetric
gravitational fields. The theory also applies to point masses embedded in an
expanding universe, were the surface gravity is still related to Kodama-Hayward
theory. As a bonus of the tunneling method, we gain the insight that the
surface gravity still defines a temperature parameter as long as the evolution
is sufficiently slow that the black hole pass through a sequence of
quasi-equilibrium states.


title:
Effect of ferromagnetic contacts on spin accumulation in an all-metallic
  lateral spin-valve system: Semiclassical spin drift-diffusion equations

abstract:
  We study the effect of the ferromagnetic (FM) contacts on the spin
accumulation in the lateral spin valve system for the collinear magnetization
configurations. When an additional FM electrode is introduced in the
all-metallic lateral spin-valve system, we find that the transresistance can be
fractionally suppressed or very weakly influenced depending on the position of
the additional FM electrode, and relative magnitudes of contact resistance and
the bulk resistance defined over the spin diffusion length. Nonlocal spin
signals such as nonlocal voltage drop and leakage spin currents are independent
of the magnetization orientation of the additional FM electrode. Even when the
additional contact is nonmagnetic, nonlocal spin signals can be changed by the
spin current leaking into the nonmagnetic electrode.


title:
Examination of unitarity condition (positive definiteness of expression
  for transition probabilities) at three neutrino oscillations in vacuum

abstract:
  This work has shown that at strict fulfilment of condition $\Delta m^2_{1 3}
= \Delta m^2_{1 2} + \Delta m^2_{2 3}$ the expression for probability of $\nu_e
\to \nu_e$ transitions $P_{\nu_e \to \nu_e}(t)$ is positively defined at every
values of $\theta$ and $\beta$ while at any arbitrarily small deviation from
this condition it becomes negative. In order to make this expression for
probability transitions positively defined, it is necessary to put a limitation
on angle mixing $\beta$ at fixed value of $\theta= 32.45^o$ (i.e. the value for
$\beta$ must be $\beta \le 15^o \div 17^o$).


title:
Only n-Qubit Greenberger-Horne-Zeilinger States are Undetermined by
  their Reduced Density Matrices

abstract:
  The generalized n-qubit Greenberger-Horne-Zeilinger (GHZ) states and their
local unitary equivalents are the only states of n qubits that are not uniquely
determined among pure states by their reduced density matrices of n-1 qubits.
Thus, among pure states, the generalized GHZ states are the only ones
containing information at the n-party level. We point out a connection between
local unitary stabilizer subgroups and the property of being determined by
reduced density matrices.


title:
Momentum dependence of the electron-phonon coupling and self-energy
  effects in YBa_2Cu_3O_7 within the local density approximation

abstract:
  Using the local density approximation (LDA) and a realistic phonon spectrum
we determine the momentum and frequency dependence of $\alpha^2F({\bf
k},\omega)$ in YBa$_2$Cu$_3$O$_7$ for the bonding, antibonding, and chain band.
The resulting self-energy $\Sigma$ is rather small near the Fermi surface. For
instance, for the antibonding band the maximum of $Re \Sigma$ as a function of
frequency is about 7 meV at the nodal point in the normal state and the ratio
of bare and renormalized Fermi velocities 1.18. These values are a factor 3-5
too small compared to the experiment showing that only a small part of $\Sigma$
can be attributed to phonons. Furthermore, the frequency dependence of the
renormalization factor $Z({\bf k},\omega)$ is smooth and has no anomalies at
the observed kink frequencies which means that phonons cannot produce
well-pronounced kinks in stoichiometric YBa$_2$Cu$_3$O$_7$, at least, within
the LDA.


title:
A negative-U interpretation of the femto-second laser pulse induced
  crystallographic expansion of a cuprate HTSC material reported recently by
  Gedik et al

abstract:
  Gedik et al have very recently demonstrated using a pump/probe femto-second
laser technique that the c-axis lattice parameter of LaCuO4+d temporarily
becomes expanded by as much as 2.5% following pulsed laser optical excitation
at 1.55 eV. Access to an out-of-equilibrium metastable excited state is
observed to develop on a time scale of 30 ps. Subsequently the latter state
decays displaying a still longer half-life of just over 300 ps. Observation of
the temperature independence of this laser induced interstate transfer and of
the linear dependence of the production of the metastable population upon the
energy delivered per unit area by the initiating light pulse (beyond a key
threshold fluence) have been interpreted by Gedik et al within the framework of
standard p-to-d, O-to-Cu, charge transfer excitations. By contrast these same
data are reinterpreted here in terms of pumped local pairs, within a negative-U
scenario of cuprate HTSC behaviour long advocated by the current author. The
d8-to-d10 laser-induced augmentation in the negative-U state population
(10CuIII2-) brings marked c-axis expansion by virtue of (i) the local
electrostatic charge imbalance, (ii) the increased antibonding nature of the
electron double-loading d10(p6) configuration created at pair-receptive CuIII
coordination units, and (iii) the layered nature of the cuprate crystal
structure. The new observations are related through to Rohlers striking,
standard crystallographic observations, to the stripe domain formation, and to
previous pump/probe experiments.


title:
Technical aspects of an impact acceleration traumatic brain injury rat
  model with potential suitability for both microdialysis and PtiO2 monitoring

abstract:
  This report describes technical adaptations of a traumatic brain injury (TBI)
model-largely inspired by Marmarou-in order to monitor microdialysis data and
PtiO2 (brain tissue oxygen) before, during and after injury. We particularly
focalize on our model requirements which allows us to re-create some drastic
pathological characteristics experienced by severely head-injured patients:
impact on a closed skull, no ventilation immediately after impact, presence of
diffuse axonal injuries and secondary brain insults from systemic origin...We
notably give priority to minimize anaesthesia duration in order to tend to
banish any neuroprotection. Our new model will henceforth allow a better
understanding of neurochemical and biochemical alterations resulting from
traumatic brain injury, using microdialysis and PtiO2 techniques already
monitored in our Intensive Care Unit. Studies on efficiency and therapeutic
window of neuroprotective pharmacological molecules are now conceivable to
ameliorate severe head-injury treatment.


title:
Bright and dark excitons in an atom--pair filled optical lattice within
  a cavity

abstract:
  We study electronic excitations of a degenerate gas of atoms trapped in pairs
in an optical lattice. Local dipole-dipole interactions produce a long lived
antisymmetric and a short lived symmetric superposition of individual atomic
excitations as the lowest internal on-site excitations. Due to the much larger
dipole moment the symmetric states couple efficiently to neighbouring lattice
sites and can be well represented by Frenkel excitons, while the antisymmetric
dark states stay localized. Within a cavity only symmetric states couple to
cavity photons inducing long range interactions to form polaritons. We
calculate their dispersion curves as well as cavity transmission and reflection
spectra to observe them. For a lattice with aspherical sites bright and dark
states get mixed and their relative excitation energies depend on photon
polarizations. The system should allow to study new types of solid state
phenomena in atom filled optical lattices.


title:
Comments on ``Spin Connection Resonance in Gravitational General
  Relativity''

abstract:
  We comment on a recent article of M.W.Evans, Acta Physica Polonica B38 (2007)
2211. We point out that the equations underlying Evans' theory are highly
problematic. Moreover, we demonstrate that the so-called ``spin connection
resonance'', predicted by Evans, cannot be derived from the equation he used.
We provide an exact solution of Evans' corresponding equation and show that is
has definitely no resonance solutions.


title:
LISA observations of supermassive black holes: parameter estimation
  using full post-Newtonian inspiral waveforms

abstract:
  We study parameter estimation of supermassive black hole binary systems in
the final stage of inspiral using the full post-Newtonian gravitational
waveforms. We restrict our analysis to systems in circular orbit with
negligible spins, in the mass range $10^8\Ms-10^5\Ms$, and compare the results
with those arising from the commonly used restricted post-Newtonian
approximation. The conclusions of this work are particularly important with
regard to the astrophysical reach of future LISA measurements. Our analysis
clearly shows that modeling the inspiral with the full post-Newtonian waveform,
not only extends the reach to higher mass systems, but also improves in general
the parameter estimation. In particular, there are remarkable improvements in
angular resolution and distance measurement for systems with a total mass
higher than $5\times10^6\Ms$, as well as a large improvement in the mass
determination.


title: Emulating Non-Abelian Topological Matter in Cold Atom Optical Lattices

abstract:
  Certain proposed extended Bose-Hubbard models may exhibit topologically
ordered ground states with excitations obeying non-Abelian braid statistics. A
sufficient tuning of Hubbard parameters could yield excitation braiding rules
allowing implementation of a universal set of topologically protected quantum
gates. We discuss potential difficulties in realizing a model with a proposed
non-Abelian topologically ordered ground state using optical lattices
containing bosonic dipoles. Our direct implementation scheme does not realize
the necessary anisotropic hopping, anisotropic interactions, and low
temperatures.


title:
An application of linear programming duality to discrete Fourier
  analysis and additive problems

abstract:
  Suppose that f is a function from Z_p -> [0,1] (Z_p is my notation for the
integers mod p, not the p-adics), and suppose that a_1,...,a_k are some places
in Z_p. In some additive number theory applications it would be nice to perturb
f slightly so that Fourier transform f^ vanishes at a_1,...,a_k, while additive
properties are left intact. In the present paper, we show that even if we are
unsuccessful in this, we can at least say something interesting by using the
principle of the separating hyperplane, a basic ingredient in linear
programming duality.


title: Ordinary-derivative formulation of conformal low-spin fields

abstract:
  Conformal fields in flat space-time of even dimension greater than or equal
to four are studied. Second-derivative formulation for spin 0,1,2 conformal
bosonic fields and first-derivative formulation for spin 1/2,3/2 conformal
fermionic fields are developed. For the spin 1,3/2,2 conformal fields, we
obtain gauge invariant Lagrangians and the corresponding gauge transformations.
Gauge symmetries are realized by involving Stueckelberg fields and auxiliary
fields. Realization of global conformal boost symmetries is obtained. Modified
Lorentz and de Donder gauge conditions are introduced. Ordinary-derivative
Lagrangian of interacting Weyl gravity in 4d is obtained. In our approach, the
field content of Weyl gravity, in addition to conformal graviton field,
includes one auxiliary rank-2 symmetric tensor field and one Stueckelberg
vector field. With respect to the auxiliary tensor field, the Lagrangian
contains, in addition to other terms, the Pauli-Fierz mass term. Using the
ordinary-derivative Lagrangian of Weyl gravity, we discuss interrelation of
Einstein AdS gravity and Weyl gravity via breaking conformal gauge symmetries.
Also, we demonstrate use of the light-cone gauge for counting on-shell degrees
of freedom in higher-derivative conformal field theories.


title:
Proper motions of radiative knots in simulations of stellar jets - An
  alternative to pulsating inflow conditions

abstract:
  Elongated jets from young stellar objects typically present a nodular
structure, formed by a chain of bright knots of enhanced emission with
individual proper motions. Though it is generally accepted that internal shocks
play an important role in the formation and dynamics of such structures, their
precise origin and the mechanisms behind the observed proper motions is still a
matter of debate. Our goal is to study numerically the origin, dynamics, and
emission properties of such knots. Axisymmetric simulations are performed with
a shock-capturing code for gas dynamics, allowing for molecular, atomic, and
ionized hydrogen in non-equilibrium concentrations subject to
ionization/recombination processes. Radiative losses in SII lines are computed,
and the resulting synthetic emission maps are compared with observations. We
show that a pattern of regularly spaced internal oblique shocks, characterized
by individual proper motions, is generated by the pressure gradient between the
propagating jet and the time variable external cocoon. In the case of
under-expanded, light jets the resulting emission knots are found to move
downstream with the jet flow, with increasing velocity and decaying brightness
toward the leading bow shock. This suggests that the basic properties of the
knots observed in stellar jets can be reproduced even without invoking ad hoc
pulsating conditions at the jet inlet, though an interplay between the two
scenarios is certainly possible.


title: Weak productions of new charmonium in semi-leptonic decays of B_c

abstract:
  We study the weak productions of novel heavy mesons, such as
$\eta_c^{\prime}$, $h_c$, $h_c^{\prime}$, $\chi_{c0}^{\prime}$, X(3940),
Y(3940), X(3872), and Y(4260), in the semi-leptonic $B_c$ decays. Since there
is still no definite answer for the components of X(3940), Y(3940), X(3872),
Y(4260) so far, we will assign them as excited charmonium states with the
possible quantum numbers constrained by the current experiments. As for the
weak transition form factors, we calculate them in the framework of light-cone
QCD sum rules approach, which is proved to be a powerful tool to deal with the
non-perturbative hadronic matrix element. Our results indicate that different
interpretations of X(3940) can result in remarkable discrepancy of the
production rate in the $B_c$ decays, which would help to clarify the inner
structure of the X(3940) with the forthcoming LHC-b experiments. Besides, the
predicted large weak production rates of X(3872) and Y(3940) in $B_c$ decays
and the small semi-leptonic decay rate for $B_c \to Y(4260)$ all depend on
their quantum number $J^{PC}$ assignments. Moreover, the $S-D$ mixing of
various vector charmonium states in the weak decay of $B_c$ is also discussed
in this work. The future experimental measurements of these decays will test
the inner structures of these particles, according to our predictions here.


title:
Reaffirming the connection between the Galactic stellar warp and the
  Canis Major overdensity

abstract:
  We perform a critical re-analysis and discussion of recent results presented
in the literature which interpret the CMa overdensity as the signature of an
accreting dwarf galaxy or a new substructure within the Galaxy. Several issues
are addressed. We show that arguments against the ``warp'' interpretation are
based on an erroneous perception of the Milky Way. There is nothing anomalous
with colour--magnitude diagrams on opposite sides of the average warp mid-plane
being different. We witnessed the rise and fall of the blue plume population,
first attributed to young stars in a disrupting dwarf galaxy and now discarded
as a normal disc population. Similarly, there is nothing anomalous in the outer
thin+thick disc metallicities being low (-1<[Fe/H]<-0.5), and spiral arms (as
part of the thin disc) should, and do, warp. Most importantly, we show
unambiguously that, contrary to previous claims, the warp produces a stellar
overdensity that is distance-compatible with that observed in CMa.The CMa
over-density remains fully accounted for in a first order approach by Galactic
models without new substructures. Given the intrinsic uncertainties (concerning
the properties of the warp, flare and disc cutoff, the role of extinction and
degeneracy), minor deviations with respect to these models are not enough to
support the hypothesis of an accreted dwarf galaxy or new substructure within
the Milky Way disc.


title: Robust ultrafast currents in molecular wires through Stark shifts

abstract:
  A novel way to induce ultrafast currents in molecular wires using two
incident laser frequencies, $\omega$ and $2\omega$, is demonstrated. The
mechanism relies on Stark shifts, instead of photon absorption, to transfer
population to the excited states and exploits the temporal profile of the field
to generate phase controllable transport. Calculations in a
\emph{trans}-polyacetylene oligomer coupled to metallic leads indicate that the
mechanism is highly efficient and robust to ultrafast electronic dephasing
processes induced by vibronic couplings.


title: Shear Viscosity of Quark Matter

abstract:
  We consider the shear viscosity of a system of quarks and its ratio to the
entropy density above the critical temperature for deconfinement. Both
quantities are derived and computed for different modeling of the quark
self-energy, also allowing for a temperature dependence of the effective mass
and width. The behaviour of the viscosity and the entropy density is argued in
terms of the strength of the coupling and of the main characteristics of the
quark self-energy. A comparison with existing results is also discussed.


title: Qubit quantum channels: A characteristic function approach

abstract:
  A characterization of qubit quantum channels is introduced. In analogy to
what happens in the context of Bosonic channels we exploit the possibility of
representing the states of the system in terms of characteristic function. The
latter are functions of non-commuting variables (Grassmann variables) and are
defined in terms of generalized displacement operators. In this context we
introduce the set of Gaussian channels and show that they share similar
properties with the corresponding Bosonic counterpart.


title: Bose-Einstein Condensates in Strongly Disordered Traps

abstract:
  A Bose-Einstein condensate in an external potential consisting of a
superposition of a harmonic and a random potential is considered theoretically.
  From a semi-quantitative analysis we find the size, shape and excitation
energy as a function of the disorder strength. For positive scattering length
and sufficiently strong disorder the condensate decays into fragments each of
the size of the Larkin length ${\cal L}$. This state is stable over a large
range of particle numbers. The frequency of the breathing mode scales as
$1/{\cal L}^2$. For negative scattering length a condensate of size ${\cal L}$
may exist as a metastable state. These finding are generalized to anisotropic
traps.


title:
Fermi Surface and Magnetism in the Kondo lattice: A Continuum Field
  Theory Approach

abstract:
  We consider the Fermi surface inside the antiferromagnetic ordered region of
a Kondo lattice system in an arbitrary dimension higher than one. We establish
the existence of ${\rm AF_S}$, an antiferromagnetic phase whose Fermi surface
is ``small,'' in the sense that the local moments do not participate in the
Fermi-surface formation. This is in contrast to the ``large'' Fermi surface
that is typically assumed for heavy fermion metals. We extend our earlier work
to the case that the Fermi surface of the conduction electrons intersects the
antiferromagnetic Brillouin zone boundary. Our results provide a new
perspective on local quantum criticality. In addition, our results imply that,
for the ${\rm AF_S}$ phase, it is important to keep track of the dynamical
screening processes; we suggest that this effect is not captured in a recent
variational Monte-Carlo study of the Kondo lattice.


title: The uvbyHbeta Metallicity Calibration for G and K Dwarfs

abstract:
  The metallicity dependence of the primary indices of the uvby photometric
system for cooler dwarfs (Teff ~ 6500 K to 5000K) is investigated. The data
base for the analysis is composed of the overlap between a composite catalog of
selected, high-dispersion spectroscopic abundances for 1801 stars on the
metallicity scale of Valenti and Fischer (2005) and a merged catalog of
high-precision uvbyHbeta photometry for over 35,000 stars. While [Fe/H] for F
dwarfs is best estimated from m_1, with a modest dependence on c_1 as expected,
for hotter G dwarfs the pattern reverses and c_1 becomes the dominant index.
For cooler G dwarfs and K stars, the c_1 dominance continues, but a
discontinuity appears such that stars between (b-y) = 0.50 and 0.58 with [Fe/H]
>= +0.25 have m_1 and c_1 indices that classify them as subgiants, confirming
an earlier result based upon a much smaller sample. The reversal in the
sensitivity to m_1 and c_1 is traced, in part, to the metallicity sensitivity
of the (b-y) index. Moreover, (b-y) grows larger in a non-linear fashion for
stars above solar metallicity, leading to an overestimate of the reddening for
super-metal-rich stars from some standard intrinsic color relations. Based upon
successful tests using indices from synthetic spectra and the empirical trends
among the observations, metallicity calibrations tied to Hbeta rather than
(b-y) have been derived for [Fe/H] >= -1.0, generating dispersions among the
residuals ranging from 0.061 dex to 0.085 dex over the entire temperature range
of interest. The new calibrations have the added advantage of being
significantly less sensitive to errors in reddening than previous calibrations.


title:
On the existence of A-loops with some commutative inner mappings and
  others of order 2

abstract:
  The existence of A$_\rho$-loops, A$_\lambda$-loops and A$_\mu$-loops that are
neither extra loops nor CC-loops such that any two of their inner mappings
$R(x,y),L(x,y)$ and $T(x)$ commute while the other one is of order 2 is shown.


title:
On sparse representations of linear operators and the approximation of
  matrix products

abstract:
  Thus far, sparse representations have been exploited largely in the context
of robustly estimating functions in a noisy environment from a few
measurements. In this context, the existence of a basis in which the signal
class under consideration is sparse is used to decrease the number of necessary
measurements while controlling the approximation error. In this paper, we
instead focus on applications in numerical analysis, by way of sparse
representations of linear operators with the objective of minimizing the number
of operations needed to perform basic operations (here, multiplication) on
these operators. We represent a linear operator by a sum of rank-one operators,
and show how a sparse representation that guarantees a low approximation error
for the product can be obtained from analyzing an induced quadratic form. This
construction in turn yields new algorithms for computing approximate matrix
products.


title:
Sur la d\'efinissabilit\'e existentielle de la non-nullit\'e dans les
  anneaux

abstract:
  We investigate the rings in which the set of nonzero elements is
positive-existential (i.e. a finite union of projections of "algebraic" sets).
In the case of Noetherian domains, we prove in particular that this condition
is satisfied whenever the ring in question is not local Henselian, while it is
not satisfied for any excellent local Henselian domain which is not a field.
  As a byproduct, we obtain an answer to a question of Popescu on strong
approximation for Henselian pairs.


title: Generalized Landau-Pollak Uncertainty Relation

abstract:
  The Landau-Pollak uncertainty relation treats a pair of rank one projection
valued measures and imposes a restriction on their probability distributions.
It gives a nontrivial bound for summation of their maximum values. We give a
generalization of this bound (weak version of the Landau-Pollak uncertainty
relation). Our generalization covers a pair of positive operator valued
measures. A nontrivial but slightly weak inequality that can treat an arbitrary
number of positive operator valued measures is also presented.


title: Free resolutions over short local rings

abstract:
  The structure of minimal free resolutions of finite modules M over
commutative local rings (R,m,k) with m^3=0 and rank_k(m^2) < rank_k(m/m^2)is
studied. It is proved that over generic R every M has a Koszul syzygy module.
Explicit families of Koszul modules are identified. When R is Gorenstein the
non-Koszul modules are classified. Structure theorems are established for the
graded k-algebra Ext_R(k,k) and its graded module Ext_R(M,k).


title:
Critical Lines and Massive Phases in Quantum Spin Ladders with
  Dimerization

abstract:
  We determine the existence of critical lines in dimerized quantum spin
ladders in their phase diagram of coupling constants using the finite-size DMRG
algorithm. We consider both staggered and columnar dimerization patterns, and
antiferromagnetic and ferromagnetic inter-leg couplings. The existence of
critical phases depends on the precise combination of these patterns. The
nature of the massive phases separating the critical lines are characterized
with generalized string order parameters that determine their valence bond
solid (VBS) content.


title: Roughness of moving elastic lines - crack and wetting fronts

abstract:
  We investigate propagating fronts in disordered media that belong to the
universality class of wetting contact lines and planar tensile crack fronts. We
derive from first principles their nonlinear equations of motion, using the
generalized Griffith criterion for crack fronts and three standard mobility
laws for contact lines. Then we study their roughness using the self-consistent
expansion. When neglecting the irreversibility of fracture and wetting
processes, we find a possible dynamic rough phase with a roughness exponent of
$\zeta=1/2$ and a dynamic exponent of z=2. When including the irreversibility,
we conclude that the front propagation can become history dependent, and thus
we consider the value $\zeta=1/2$ as a lower bound for the roughness exponent.
Interestingly, for propagating contact line in wetting, where irreversibility
is weaker than in fracture, the experimental results are close to 0.5, while
for fracture the reported values of 0.55--0.65 are higher.


title:
Monte Carlo studies of supersymmetric matrix quantum mechanics with
  sixteen supercharges at finite temperature

abstract:
  We present the first Monte Carlo results for supersymmetric matrix quantum
mechanics with sixteen supercharges at finite temperature. The recently
proposed non-lattice simulation enables us to include the effects of fermionic
matrices in a transparent and reliable manner. The internal energy nicely
interpolates the weak coupling behavior obtained by the high temperature
expansion, and the strong coupling behavior predicted from the dual black hole
geometry. The Polyakov line takes large values even at low temperature
suggesting the absence of a phase transition in sharp contrast to the bosonic
case. These results provide highly non-trivial evidences for the gauge/gravity
duality.


title: Phantom cosmologies and fermions

abstract:
  Form invariance transformations can be used for constructing phantom
cosmologies starting with conventional cosmological models. In this work we
reconsider the scalar field case and extend the discussion to fermionic fields,
where the "phantomization" process exhibits a new class of possible accelerated
regimes. As an application we analyze the cosmological constant group for a
fermionic seed fluid.


title: The Poincar\'e Recurrence Problem of Inviscid Incompressible Fluids

abstract:
  Nadirashvili presented a beautiful example showing that the Poincar\'e
recurrence does not occur near a particular solution to the 2D Euler equation
of inviscid incompressible fluids. Unfortunately, Nadirashvili's setup of the
phase space is not appropriate, and details of the proof are missing. This note
fixes that.

categories: math.AP math-ph math.DS math.MP physics.flu-dyn


title:
Long-time stable HTSC DC-SQUID gradiometers with silicon dioxide
  passivation for measurements with superconducting flux transformers

abstract:
  In applications for high-Tc superconducting DC-SQUIDs such as biomagnetism,
nondestructive evaluation and the relaxation of magnetic nanoparticles, it is
important to maintain reliable sensor performance over an extended time period.
We designed and produced DC-SQUID gradiometers based on YBCO thin films which
are inductively coupled to a flux transformer to achieve a higher sensitivity.
The gradiometers are protected against ambient atmosphere and humidity by SiO2
and amorphous YBCO layers.
  The noise properties of the sensor in flip-chip configuration, especially in
unshielded environments, are shown. We present a comparison of TBCCO thin films
on buffered sapphire or LaAlO3 substrates for the flux transformer in shielded
and unshielded environments. We reach a low white field gradient noise of 72
fT/(cm sqrt(Hz)) with the TBCCO on LaAlO3 flux transformer. The electric
properties of the gradiometers (critical current IC, normal state resistance RN
and the transfer function VPhi) were measured over a period of one year and do
not show significant signs of degradation.


title: A Recurrence Theorem on the Solutions to the 2D Euler Equation

abstract:
  In this article, I will prove a recurrence theorem which says that any
$H^s(\mathbb{T}^2)$ (s>2) solution to the 2D Euler equation returns repeatedly
to an arbitrarily small $H^0(\mathbb{T}^2)$ neighborhood.


title: Segment Description of Turbulence

abstract:
  We propose a segment description for turbulent solutions to evolution
equations in an effort to develop an effective description rather than the
classical Reynolds average. The new description has connections with symbolic
dynamics and shadowing technique. The challenge of future study is how to
effectively implement the description numerically.


title:
A combinatorial basis for the free Lie algebra of the labelled rooted
  trees

abstract:
  The pre-Lie operad can be realized as a space T of labelled rooted trees. A
result of F. Chapoton shows that the pre-Lie operad is a free twisted Lie
algebra. That is, the S-module T is obtained as the plethysm of the S-module
Lie with an S-module F. In the context of species, we construct an explicit
basis of F. This allows us to give a new proof of Chapoton's results. Moreover
it permits us to show that F forms a sub nonsymmetric operad of the pre-Lie
operad T.


title: Shubnikov-de Haas oscillations in YBa_2Cu_4O_8

abstract:
  We report the observation of Shubnikov-de Haas oscillations in the underdoped
cuprate superconductor YBa$_2$Cu$_4$O$_8$ (Y124). For field aligned along the
c-axis, the frequency of the oscillations is $660\pm 30$ T, which corresponds
to $\sim 2.4$ % of the total area of the first Brillouin zone. The effective
mass of the quasiparticles on this orbit is measured to be $2.7\pm0.3$ times
the free electron mass. Both the frequency and mass are comparable to those
recently observed for ortho-II YBa$_2$Cu$_3$O$_{6.5}$ (Y123-II). We show that
although small Fermi surface pockets may be expected from band structure
calculations in Y123-II, no such pockets are predicted for Y124. Our results
therefore imply that these small pockets are a generic feature of the copper
oxide plane in underdoped cuprates.


title: Gamma Air Watch (GAW): the electronics and trigger concept

abstract:
  GAW proposes a new approach for the detection and measurement of the
Cherenkov light produced by GeV/TeV gamma rays traversing the Earth atmosphere
which imposes specific requirements on the electronics design. The focal
surface of the GAW telescope consists of a matrix of multi-anode
photomultipliers. The large number of active channels (of the order of 10^5)
makes it basically a large UV sensitive digital camera with high resolution
imaging capability. The limited amount of space available, due to the large
number of channels, requires a compact design with minimal distance between the
elements of the focal surface. The front-end electronics uses the single
photoelectron counting technique to capture the Cherenkov light. The data
acquisition is based on free-running data taking method. Self-triggering
capability for each telescope is assured by detecting an excess of active
pixels, in a 10ns time frame, inside overlapping trigger areas covering the
whole focal surface. In this paper we describe the GAW electronics, as well as
the trigger concept and implementation.