title: Formation of negative hydrogen ion in Positronium - Hydrogen collisions

abstract:
  The importance of the excited states of Positronium (Ps) in the formation
cross sections(both differential and total) of the negative hydrogen ion (H^-)
are investigated theoretically for the charge transfer reaction, Ps (n = 1, 2)
+ H --> e+ + H^- for a wide range of incident energies (e. g., threshold - 500
eV) . The calculations are performed in the frame work of a qualitative model,
the post collisional Coulomb Modified Eikonal Approximation (CMEA) . A
comparative study is also made between the capture from ground and excited
states of the Ps. The present CMEA model takes account of higher order effects
which is essential for a rearrangement process where the First Born type
Approximation (Coulomb Born for the ionic case) is not supposed to be adequate.
At low incident energies, the excited states of Ps (2s, 2p) are found to play a
dominant role in the H^- formation cross sections . Significant deviations are
noted between the present CMEA and the Coulomb Born (CBA) results even at very
high incident energies (e.g., Ei = 500 eV), indicating the importance of higher
order effects. At high incident energies the present CMEA differential cross
section (DCS) exhibits a double peak structure which is totally absent in the
CBA and could again be attributed to higher order effects.


title: Deeply Virtual Pseudoscalar Meson Production with CLAS

abstract:
  Deeply virtual meson scattering cross sections and asymmetries for the pi^0
and eta exclusive electroproduction in a very wide kinematic range of Q^2, t
and x_B have been measured with CLAS (JLab). Initial analysis is already
showing remarkable results. These data will help us to better understand the
transition from soft to hard mechanisms.


title: A simplified global solution for an advection-dominated accretion flow

abstract:
  When we model black hole accretion sources such as active galactic nuclei and
black hole X-ray binaries as advection-dominated accretion flows (ADAFs), it is
neccesary to use the global solution to the equations rather than the simpler
self-similar solution, since the latter is inaccurate in the region near the
black hole where most of the radiation is emitted. However, technically, it is
a difficult task to calculate the global solution because of the transonic
nature of the flow, which makes it a two-point boundary value problem. In this
paper we propose a simplified approach for calculating the global ADAF
solution. We replace the radial momentum equation by a simple algebraic
relation between the angular velocity of the gas and the Keplerian angular
velocity, while keeping all other equations unchanged. It is then easy to solve
the differential energy equations to obtain an approximate global solution. By
adjusting the free parameters, we find that for almost any accretion rate and
for $\alpha=0.1-0.3$ we can get good simplified global solutions. The predicted
spectra from the approximate solutions are very close to the spectra obtained
from the true global solutions.


title:
Statistics of gravitational potential perturbations: A novel approach to
  deriving the X-ray temperature function

abstract:
  Context. While the halo mass function is theoretically a very sensitive
measure of cosmological models, masses of dark-matter halos are poorly defined,
global, and unobservable quantities.
  Aims. We argue that local, observable quantities such as the X-ray
temperatures of galaxy clusters can be directly compared to theoretical
predictions without invoking masses. We derive the X-ray temperature function
directly from the statistics of Gaussian random fluctuations in the
gravitational potential.
  Methods. We derive the abundance of potential minima constrained by the
requirement that they belong to linearly collapsed structures. We then use the
spherical-collapse model to relate linear to non-linear perturbations, and the
virial theorem to convert potential depths to temperatures. No reference is
made to mass or other global quantities in the derivation.
  Results. Applying a proper high-pass filter that removes large enough modes
from the gravitational potential, we derive an X-ray temperature function that
agrees very well with the classical Press-Schechter approach on relevant
temperature scales, but avoids the necessity of measuring masses.
  Conclusions. TThis first study shows that and how an X-ray temperature
function of galaxy clusters can be analytically derived, avoiding the
introduction of poorly defined global quantities such as halo masses. This
approach will be useful for reducing scatter in observed cluster distributions
and thus in cosmological conclusions drawn from them.


title: Symmetric tensors and symmetric tensor rank

abstract:
  A symmetric tensor is a higher order generalization of a symmetric matrix. In
this paper, we study various properties of symmetric tensors in relation to a
decomposition into a sum of symmetric outer product of vectors. A rank-1
order-k tensor is the outer product of k non-zero vectors. Any symmetric tensor
can be decomposed into a linear combination of rank-1 tensors, each of them
being symmetric or not. The rank of a symmetric tensor is the minimal number of
rank-1 tensors that is necessary to reconstruct it. The symmetric rank is
obtained when the constituting rank-1 tensors are imposed to be themselves
symmetric. It is shown that rank and symmetric rank are equal in a number of
cases, and that they always exist in an algebraically closed field. We will
discuss the notion of the generic symmetric rank, which, due to the work of
Alexander and Hirschowitz, is now known for any values of dimension and order.
We will also show that the set of symmetric tensors of symmetric rank at most r
is not closed, unless r = 1.


title: Squeezed vacuum as a universal quantum probe

abstract:
  We address local quantum estimation of bilinear Hamiltonians probed by
Gaussian states. We evaluate the relevant quantum Fisher information (QFI) and
derive the ultimate bound on precision. Upon maximizing the QFI we found that
single- and two-mode squeezed vacuum represent an optimal and universal class
of probe states, achieving the so-called Heisenberg limit to precision in terms
of the overall energy of the probe. We explicitly obtain the optimal observable
based on the symmetric logarithmic derivative and also found that homodyne
detection assisted by Bayesian analysis may achieve estimation of squeezing
with near-optimal sensitivity in any working regime. Besides, by comparison of
our results with those coming from global optimization of the measurement we
found that Gaussian states are effective resources, which allow to achieve the
ultimate bound on precision imposed by quantum mechanics using measurement
schemes feasible with current technology.


title:
Crossover from Reptation to Rouse dynamics in the Extended
  Rubinstein-Duke Model

abstract:
  The competition between reptation and Rouse Dynamics is incorporated in the
Rubinstein-Duke model for polymer motion by extending it with sideways motions,
which cross barriers and create or annihilate hernias. Using the Density-Matrix
Renormalization-Group Method as solver of the Master Equation, the renewal time
and the diffusion coefficient are calculated as function of the length of the
chain and the strength of the sideways motion. These new types of moves have a
strong and delicate influence on the asymptotic behavior of long polymers. The
effects are analyzed as function of the chain length in terms of effective
exponents and crossover scaling functions.


title: High-fidelity readout of trapped-ion qubits

abstract:
  We demonstrate single-shot qubit readout with fidelity sufficient for
fault-tolerant quantum computation, for two types of qubit stored in single
trapped calcium ions. For an optical qubit stored in the (4S_1/2, 3D_5/2)
levels of 40Ca+ we achieve 99.991(1)% average readout fidelity in one million
trials, using time-resolved photon counting. An adaptive measurement technique
allows 99.99% fidelity to be reached in 145us average detection time. For a
hyperfine qubit stored in the long-lived 4S_1/2 (F=3, F=4) sub-levels of 43Ca+
we propose and implement a simple and robust optical pumping scheme to transfer
the hyperfine qubit to the optical qubit, capable of a theoretical fidelity
99.95% in 10us. Experimentally we achieve 99.77(3)% net readout fidelity,
inferring at least 99.87(4)% fidelity for the transfer operation.


title: Generalized Whac-a-Mole

abstract:
  We consider online competitive algorithms for the problem of collecting
weighted items from a dynamic set S, when items are added to or deleted from S
over time. The objective is to maximize the total weight of collected items. We
study the general version, as well as variants with various restrictions,
including the following: the uniform case, when all items have the same weight,
the decremental sets, when all items are present at the beginning and only
deletion operations are allowed, and dynamic queues, where the dynamic set is
ordered and only its prefixes can be deleted (with no restriction on
insertions). The dynamic queue case is a generalization of bounded-delay packet
scheduling (also referred to as buffer management). We present several upper
and lower bounds on the competitive ratio for these variants.


title: Proton Profile Function at 52.8 GeV

abstract:
  We present the results of a novel model-independent fit to elastic
proton-proton differential cross section data at $\sqrt s$ = 52.8 GeV. Taking
into account the error propagation from the fit parameters, we determine the
scattering amplitude in the impact parameter space (the proton profile
function) and its statistical uncertainty region. We show that both the real
and imaginary parts of the profile are consistent with two dynamical
contributions, one from a central dense region, up to roughly 1 fm and another
from a peripheral evanescent region from 1 to 3 fm.


title: Low-lying dipole resonance in neutron-rich Ne isotopes

abstract:
  Microscopic structure of the low-lying isovector dipole excitation mode in
neutron-rich $^{26,28,30}$Ne is investigated by performing deformed
quasiparticle-random-phase-approximation (QRPA) calculations. The particle-hole
residual interaction is derived from a Skyrme force through a Landau-Migdal
approximation. We have obtained the low-lying resonance in $^{26}$Ne at around
8.5 MeV. It is found that the isovector dipole strength at $E_{x}<10$ MeV
exhausts about 6.0% of the classical Thomas-Reiche-Kuhn dipole sum rule. This
excitation mode is composed of several QRPA eigenmodes, one is generated by a
$\nu(2s^{-1}_{1/2} 2p_{3/2})$ transition dominantly, and the other mostly by a
$\nu(2s^{-1}_{1/2} 2p_{1/2})$ transition. The neutron excitations take place
outside of the nuclear surface reflecting the spatially extended structure of
the $2s_{1/2}$ wave function. In $^{30}$Ne, the deformation splitting of the
giant resonance is large, and the low-lying resonance is overlapping with the
giant resonance.


title:
Observation of Ultra-narrow Electromagnetically Induced Transparency and
  Slow Light using Purely Electronic Spins in a Hot Atomic Vapor

abstract:
  Electromagnetically induced transparency (EIT) is observed in gaseous 4He at
room temperature. Ultra-narrow (less than 10 kHz) EIT windows are obtained for
the first time for purely electronic spins in the presence of Doppler
broadening. The positive role of collisions is emphasized through measurements
of the power dependence of the EIT resonance. Measurement of slow light opens
up possible ways to applications.


title: SN1987A Pulsar Velocity From Modified URCA Processes and Landau Levels

abstract:
  Using a recent estimate of the velocity of pulsars arising from neutrinos
emitted with modified URCA processes with electrons in Landua levels, and the
temperture of the protoneutron star created by SN1987A, derived from the energy
of the observed neutrinos, we predict the velocity of the resulting pulsar.


title: More on the Bernoulli and Taylor Formula for Extended Umbral Calculus

abstract:
  One delivers here the extended Bernoulli and Taylor formula of a new sort
with the rest term of the Cauchy type recently derived by the author in the
case of the so called $\psi$-difference calculus which constitutes the
representative for the purpose case of extended umbral calculus. The central
importance of such a type formulas is beyond any doubt. Recent publications do
confirm this historically established experience. Its links via umbrality to
combinatorics are known at least since Rota and Mullin source papers then up to
recently extended by many authors to be indicated in the sequel.


title:
Complex geometric optics for symmetric hyperbolic systems I: linear
  theory

abstract:
  We obtain an asymptotic solution for $\ep \to 0$ of the Cauchy problem for
linear first-order symmetric hyperbolic systems with oscillatory initial values
written in the eikonal form of geometric optics with frequency $1/\ep$, but
with complex phases. For the most common linear wave propagation models, this
kind on Cauchy problems are well-known in the applied literature and their
asymptotic theory, referred to as complex geometric optics, is attracting
interest for applications. In this work, which is the first of a series of
papers dedicated to complex geometric optics for nonlinear symmetric hyperbolic
systems, we develop a rigorous linear theory and set the basis for the
subsequent nonlinear analysis.


title: Preliminary Orbit of the Young Binary Haro 1-14c

abstract:
  Using the Keck Interferometer, we spatially resolved the orbit of the
pre-main sequence binary, Haro 1-14c, for the first time. We present these
interferometric observations along with additional spectroscopic radial
velocity measurements of the components. We performed a simultaneous orbit fit
to the interferometric visibilities and the radial velocities of Haro 1-14c.
Based on a statistical analysis of the possible orbital solutions that fit the
data, we determined component masses of M_1 = 0.96 (+0.27/-0.08) Msun and M_2 =
0.33 (+0.09/-0.02) Msun for the primary and secondary, respectively, and a
distance to the system of 111 (+19/-18) pc. The distance measurement is
consistent with the close distance estimates of the Ophiuchus molecular cloud.
Comparing our results with evolutionary tracks suggests an age of 3-4 Myr for
Haro 1-14c. With additional interferometric measurements to improve the
uncertainties in the masses and distance, we expect the low-mass secondary to
provide important empirical data for calibrating the theoretical evolutionary
tracks for pre-main sequence stars.


title:
Embedding A4 into SU(3)xU(1) flavor symmetry: Large neutrino mixing and
  fermion mass hierarchy in SO(10) GUT

abstract:
  We present a common explanation of the fermion mass hierarchy and the large
lepton mixing angles in the context of a grand unified flavor and gauge theory
(GUTF). Our starting point is a SU(3)xU(1) flavor symmetry and a SO(10) GUT, a
basic ingredient of our theory which plays a major role is that two different
breaking pattern of the flavor symmetry are at work. On one side, the dynamical
breaking of SU(3)xU(1) flavor symmetry into U(2)xZ_3 explains why one family is
much heavier than the others. On the other side, an explicit symmetry breaking
of SU(3) into a discrete flavor symmetry leads to the observed tribimaximal
mixing for the leptons. We write an explicit model where this discrete symmetry
group is A4. Naturalness of the charged fermion mass hierarchy appears as a
consequence of the continuous SU(3) flavor symmetry. Moreover, the same
discrete A4-GUT invariant operators are the root of the large lepton mixing,
small Cabibbo angle, and neutrino masses.


title: Thermo-Rotational Instability in Plasma Disks Around Compact Objects

abstract:
  Differentially rotating plasma disks, around compact objects, that are
imbedded in a ``seed'' magnetic field are shown to develop vertically localized
ballooning modes that are driven by the combined radial gradient of the
rotation frequency and vertical gradients of the plasma density and
temperature. When the electron mean free path is shorter than the disk height
and the relevant thermal conductivity can be neglected, the vertical particle
flows produced by of these modes have the effect to drive the density and
temperature profiles toward the ``adiabatic condition'' where
$\eta_{T}\equiv(dlnT/dz)/(dlnn/dz)=2/3$. Here $T$ is the plasma temperature and
$n$ the particle density. The faster growth rates correspond to steeper
temperature profiles $(\eta_{T}>2/3)$ such as those produced by an internal
(e.g., viscous) heating process. In the end, ballooning modes excited for
various values of $\eta_{T}$ can lead to the evolution of the disk into a
different current carrying configuration such as a sequence of plasma rings.


title:
Identified charged antiparticle to particle ratios near midrapidity in
  Cu+Cu collisions at sqrt(s) = 62.4 and 200 GeV

abstract:
  Antiparticle to particle ratios for identified protons, kaons and pions at
sqrt(s) = 62.4 and 200 GeV in Cu+Cu collisions are presented as a function of
centrality for the midrapidity region of 0.2 < eta < 1.4. No strong dependence
on centrality is observed. For the <pbar>/<p> ratio at <p_T> ~ 0.51 GeV/c, we
observe an average value of 0.50 +/- 0.003_(stat) +/- 0.04_(syst) and 0.77 +/-
0.008_(stat) +/- 0.05_(syst) for the 10% most central collisions of 62.4 and
200 GeV Cu+Cu, respectively. The values for all three particle species measured
at sqrt(s) = 200 GeV are in agreement within systematic uncertainties with that
seen in both heavier and lighter systems measured at the same RHIC energy. This
indicates that system size does not appear to play a strong role in determining
the midrapidity chemical freeze-out properties affecting the antiparticle to
particle ratios of the three most abundant particle species produced in these
collisions.


title: First Observations on Prefab Posets Whitney Numbers

abstract:
  We introduce a natural partial order in structurally natural finite subsets
of the cobweb prefabs sets recently constructed by the present author. Whitney
numbers of the second kind of the corresponding subposet which constitute
Stirling like numbers triangular array are then calculated and the explicit
formula for them is provided. Next, in the second construction we endow the set
sums of prefabiants with such an another partial order that their Bell like
numbers include Fibonacci triad sequences introduced recently by the present
author in order to extend famous relation between binomial Newton coefficients
and Fibonacci numbers onto the infinity of their relatives among whom there are
also the Fibonacci triad sequences and binomial like coefficients (incidence
coefficients included). The first partial order is F sequence independent while
the second partial order is F sequence dependent where F is the so called
admissible sequence determining cobweb poset by construction. An F determined
cobweb posets Hasse diagram becomes Fibonacci tree sheathed with specific
cobweb if the sequence F is chosen to be just the Fibonacci sequence. From the
stand-point of linear algebra of formal series these are generating functions
which stay for the so called extended coherent states of quantum physics. This
information is delivered in the last section.


title:
Complex geometric optics for symmetric hyperbolic systems II: nonlinear
  theory in one space dimension

abstract:
  This is the second part of a work aimed to study complex-phase oscillatory
solutions of nonlinear symmetric hyperbolic systems. We consider, in
particular, the case of one space dimension. That is a remarkable case, since
one can always satisfy the \emph{naive} coherence condition on the complex
phases, which is required in the construction of the approximate solution.
Formally the theory applies also in several space dimensions, but the
\emph{naive} coherence condition appears to be too restrictive; the
identification of the optimal coherence condition is still an open problem.


title:
Escort mean values and the characterization of power-law-decaying
  probability densities

abstract:
  Escort mean values (or $q$-moments) constitute useful theoretical tools for
describing basic features of some probability densities such as those which
asymptotically decay like {\it power laws}. They naturally appear in the study
of many complex dynamical systems, particularly those obeying nonextensive
statistical mechanics, a current generalization of the Boltzmann-Gibbs theory.
They recover standard mean values (or moments) for $q=1$. Here we discuss the
characterization of a (non-negative) probability density by a suitable set of
all its escort mean values together with the set of all associated normalizing
quantities, provided that all of them converge. This opens the door to a
natural extension of the well known characterization, for the $q=1$ instance,
of a distribution in terms of the standard moments, provided that {\it all} of
them have {\it finite} values. This question would be specially relevant in
connection with probability densities having {\it divergent} values for all
nonvanishing standard moments higher than a given one (e.g., probability
densities asymptotically decaying as power-laws), for which the standard
approach is not applicable. The Cauchy-Lorentz distribution, whose second and
higher even order moments diverge, constitutes a simple illustration of the
interest of this investigation. In this context, we also address some
mathematical subtleties with the aim of clarifying some aspects of an
interesting non-linear generalization of the Fourier Transform, namely, the
so-called $q$-Fourier Transform.


title: Longest paths in Planar DAGs in Unambiguous Logspace

abstract:
  We show via two different algorithms that finding the length of the longest
path in planar directed acyclic graph (DAG) is in unambiguous logspace UL, and
also in the complement class co-UL. The result extends to toroidal DAGs as
well.


title:
An Analytical Study in Coupled Map Lattices of Synchronized States and
  Travelling Waves, and of their Period-Doubling Cascades

abstract:
  Several theorems are demonstrated that determine the sufficient conditions
for the existence of synchronized states (periodical and chaotic) and also of
travelling waves in a CML. Also are analytically proven the existence of
period-doubling cascades for the mentioned patterns. The temporal state of any
oscillators are completely characterized. The given results are valid for a
number of arbitrary oscillators whose individual dynamics is ruled by an
arbitrary C^{2} function.


title:
Breakdown of integrability in a quasi-one-dimensional ultracold bosonic
  gas

abstract:
  We demonstrate that virtual excitations of higher radial modes in an atomic
Bose gas in a tightly confining waveguide result in effective three-body
collisions that violate integrability in this quasi-one-dimensional quantum
system and give rise to thermalization. The estimated thermalization rates are
consistent with recent experimental results in quasi-1D dynamics of ultracold
atoms.


title: Crowding at the Front of the Marathon Packs

abstract:
  We study the crowding of near-extreme events in the time gaps between
successive finishers in major international marathons. Naively, one might
expect these gaps to become progressively larger for better-placing finishers.
While such an increase does indeed occur from the middle of the finishing pack
down to approximately 20th place, the gaps saturate for the first 10-20
finishers. We give a probabilistic account of this feature. However, the data
suggests that the gaps have a weak maximum around the 10th place, a feature
that seems to have a sociological origin.


title: Lagrangian Floer theory on compact toric manifolds I

abstract:
  The present authors introduced the notion of \emph{weakly unobstructed}
Lagrangian submanifolds and constructed their \emph{potential function}
$\mathfrak{PO}$ purely in terms of $A$-model data in [FOOO2]. In this paper, we
carry out explicit calculations involving $\mathfrak{PO}$ on toric manifolds
and study the relationship between this class of Lagrangian submanifolds with
the earlier work of Givental [Gi1] which advocates that quantum cohomology ring
is isomorphic to the Jacobian ring of a certain function, called the
Landau-Ginzburg superpotential. Combining this study with the results from
[FOOO2], we also apply the study to various examples to illustrate its
implications to symplectic topology of Lagrangian fibers of toric manifolds. In
particular we relate it to Hamiltonian displacement property of Lagrangian
fibers and to Entov-Polterovich's symplectic quasi-states.


title: Magnetar-like Emission from the Young Pulsar in Kes 75

abstract:
  We report detection of magnetar-like X-ray bursts from the young pulsar PSR
J1846-0258, at the center of the supernova remnant Kes 75. This pulsar, long
thought to be rotation-powered, has an inferred surface dipolar magnetic field
of 4.9x10^13 G, higher than those of the vast majority of rotation-powered
pulsars, but lower than those of the ~12 previously identified magnetars. The
bursts were accompanied by a sudden flux increase and an unprecedented change
in timing behavior. These phenomena lower the magnetic and rotational
thresholds associated with magnetar-like behavior, and suggest that in neutron
stars there exists a continuum of magnetic activity that increases with
inferred magnetic field strength.


title:
Multi-Wavelength Constraints on the Day-Night Circulation Patterns of HD
  189733b

abstract:
  We present new Spitzer observations of the phase variation of the hot Jupiter
HD 189733b in the MIPS 24 micron bandpass, spanning the same part of the
planet's orbit as our previous observations in the IRAC 8 micron bandpass
(Knutson et al. 2007). We find that the minimum hemisphere-averaged flux from
the planet in this bandpass is 76 +/- 3% of the maximum flux; this corresponds
to minimum and maximum hemisphere-averaged brightness temperatures of 984 +/-
48 K and 1220 +/- 47 K, respectively. The planet reaches its maximum flux at an
orbital phase of 0.396 +/- 0.022, corresponding to a hot region shifted 20-30
degrees east of the substellar point. Because tidally locked hot Jupiters would
have enormous day-night temperature differences in the absence of winds, the
small amplitude of the observed phase variation indicates that the planet's
atmosphere efficiently transports thermal energy from the day side to the night
side at the 24 micron photosphere, leading to modest day-night temperature
differences. The similarities between the 8 and 24 micron phase curves for HD
189733b lead us to conclude that the circulation on this planet behaves in a
fundamentally similar fashion across the range of pressures sensed by these two
wavelengths. One-dimensional radiative transfer models indicate that the 8
micron band should probe pressures 2-3 times greater than at 24 micron,
although the uncertain methane abundance complicates the interpretation. If
these two bandpasses do probe different pressures, it would indicate that the
temperature varies only weakly between the two sensed depths, and hence that
the atmosphere is not convective at these altitudes. (abridged)


title:
Effective Batalin--Vilkovisky theories, equivariant configuration spaces
  and cyclic chains

abstract:
  Kontsevich's formality theorem states that the differential graded Lie
algebra of multidifferential operators on a manifold M is
L-infinity-quasi-isomorphic to its cohomology. The construction of the
L-infinity map is given in terms of integrals of differential forms on
configuration spaces of points in the upper half-plane. Here we consider
configuration spaces of points in the disk and work equivariantly with respect
to the rotation group. This leads to considering the differential graded Lie
algebra of multivector fields endowed with a divergence operator. In the case
of R^d with standard volume form, we obtain an L-infinity morphism of modules
over this differential graded Lie algebra from cyclic chains of the algebra of
functions to multivector fields. As a first application we give a construction
of traces on algebras of functions with star-products associated with
unimodular Poisson structures. The construction is based on the
Batalin--Vilkovisky quantization of the Poisson sigma model on the disk and in
particular on the treatment of its zero modes.


title: Horizontal Branch stars as AmFm/HgMn stars

abstract:
  Recent observations and models for horizontal branch stars are briefly
described and compared to models for AmFm stars. The limitations of those
models are emphasized by a comparison to observations and models for HgMn
stars.


title: Classification of the separable maps which preserve Werner states

abstract:
  We classify the completely-positive maps acting on two $d$-dimensional
systems which commute with all $U\otimes U$ unitaries, where $U\in SU(d)$. This
set of operations map Werner states to Werner states. We find a simple
condition for a map being implementable by stochastic local operations and
classical communication (SLOCC). We show that all PPT-preserving maps can be
implemented by SLOCC. This can be used to prove that the entanglement of Werner
states cannot be stochastically increased, even if we allow PPT entanglement
for free.


title: AGILE detection of a strong gamma-ray flare from the blazar 3C 454.3

abstract:
  We report the first blazar detection by the AGILE satellite. AGILE detected
3C 454.3 during a period of strongly enhanced optical emission in July 2007.
AGILE observed the source with a dedicated repointing during the period 2007
July 24-30 with its two co-aligned imagers, the Gamma-Ray Imaging Detector and
the hard X-ray imager Super-AGILE sensitive in the 30 MeV-50 GeV and 18-60 keV,
respectively. Over the entire period, AGILE detected gamma-ray emission from 3C
454.3 at a significance level of 13.8-$\sigma$ with an average flux (E$>$100
MeV) of $(280 \pm 40) \times 10^{-8}$ photons cm$^{-2}$ s$^{-1}$. The gamma-ray
flux appears to be variable towards the end of the observation. No emission was
detected by Super-AGILE in the energy range 20-60 keV, with a 3-$\sigma$ upper
limit of $2.3 \times 10^{-3}$ photons cm$^{-2}$ s$^{-1}$. The gamma-ray flux
level of 3C 454.3 detected by AGILE is the highest ever detected for this
quasar and among the most intense gamma-ray fluxes ever detected from Flat
Spectrum Radio Quasars.


title: How accurately can 21 cm tomography constrain cosmology?

abstract:
  There is growing interest in using 3-dimensional neutral hydrogen mapping
with the redshifted 21 cm line as a cosmological probe, as it has been argued
to have a greater long-term potential than the cosmic microwave background.
However, its utility depends on many assumptions. To aid experimental planning
and design, we quantify how the precision with which cosmological parameters
can be measured depends on a broad range of assumptions. We cover assumptions
related to modeling of the ionization power spectrum and associated
nonlinearity, experimental specifications like array layout and noise,
cosmological assumptions about reionization history and inter-galactic medium
(IGM) evolution, and assumptions about astrophysical foregrounds. We derive
simple analytic approximations for how various assumptions affect the results,
and find that ionization power modeling is most important, followed by array
layout (crudely, the more compact, the better). We also present an accurate yet
robust method for measuring cosmological parameters in practice, separating the
physics from the astrophysics by exploiting both gravitationally induced
clustering anisotropy and the fact that the ionization power spectra are rather
smooth functions that can be accurately fit by 7 phenomenological parameters.
For example, a future square kilometer array optimized for 21 cm tomography
could improve the sensitivity of the Planck CMB satellite to spatial curvature
and neutrino masses by up to two orders of magnitude, to Delta-Omega_k ~ 0.0002
and Delta m_nu ~ 0.007 eV, and give a 4 sigma detection of the spectral index
running predicted by the simpliest inflation models.


title: Localized Magnetic States in Graphene

abstract:
  We examine the conditions necessary for the presence of localized magnetic
moments on adatoms with inner shell electrons in graphene. We show that the low
density of states at the Dirac point, and the anomalous broadening of the
adatom electronic level,lead to the formation of magnetic moments for
arbitrarily small local charging energy. As a result, we obtain an anomalous
scaling of the boundary separating magnetic and non-magnetic states. We show
that, unlike any other material, the formation of magnetic moments can be
controlled by an electric field effect.


title: An extremely luminous X-ray outburst at the birth of a supernova

abstract:
  Massive stars end their short lives in spectacular explosions, supernovae,
that synthesize new elements and drive galaxy evolution. Throughout history
supernovae were discovered chiefly through their delayed optical light,
preventing observations in the first moments (hours to days) following the
explosion. As a result, the progenitors of some supernovae and the events
leading up to their violent demise remain intensely debated. Here we report the
serendipitous discovery of a supernova at the time of explosion, marked by an
extremely luminous X-ray outburst. We attribute the outburst to the break-out
of the supernova shock-wave from the progenitor, and show that the inferred
rate of such events agrees with that of all core-collapse supernovae. We
forecast that future wide-field X-ray surveys will catch hundreds of supernovae
each year in the act of explosion, and thereby enable crucial neutrino and
gravitational wave detections that may ultimately unravel the explosion
mechanism.


title:
HI aperture synthesis and optical observations of the pair of galaxies
  NGC 6907 and 6908

abstract:
  NGC 6908, a S0 galaxy situated in direction of NGC 6907, was only recently
recognized as a distinct galaxy, instead of only a part of NGC 6907. We present
21 cm radio synthesis observations obtained with the GMRT and optical images
and spectroscopy obtained with the Gemini North telescope of this pair of
interacting galaxies. From the radio observations we obtained the velocity
field and the HI column density map of the whole region containing the NGC
6907/8 pair, and by means of the Gemini multi-object spectroscopy we obtained
high quality photometric images and $5 {\AA}$ resolution spectra sampling the
two galaxies. By comparing the rotation curve of NGC 6907 obtained from the two
opposite sides around the main kinematic axis, we were able to distinguish the
normal rotational velocity field from the velocity components produced by the
interaction between the two galaxies. Taking into account the rotational
velocity of NGC 6907 and the velocity derived from the absorption lines for NGC
6908, we verified that the relative velocity between these systems is lower
than 60 km s$^{-1}$. The emission lines observed in the direction of NGC 6908,
not typical of S0 galaxies, have the same velocity expected for the NGC 6907
rotation curve. Some of them, superimposed on the absorption profiles, which
reinforces the idea that they were not formed in NGC 6908. Finally, the HI
profile exhibits details of the interaction, showing three components: one for
NGC 6908, another for the excited gas in the NGC 6907 disk and a last one for
the gas with higher relative velocities left behind NGC 6908 by dynamical
friction, used to estimate the time when the interaction started in $(3.4 \pm
0.6)\times10^7$ years ago.


title:
Instabilities of an anisotropically expanding non-Abelian plasma: 1D+3V
  discretized hard-loop simulations

abstract:
  Non-Abelian plasma instabilities play a crucial role in the nonequilibrium
dynamics of a weakly coupled quark-gluon plasma and they importantly modify the
standard perturbative bottom-up thermalization scenario in heavy-ion
collisions. Using the auxiliary-field formulation of the hard-loop effective
theory, we study numerically the real time evolution of instabilities in an
anisotropic collisionless Yang-Mills plasma expanding longitudinally in free
streaming. In this first real-time lattice simulation we consider the most
unstable modes, long-wavelength coherent color fields that are constant in
transverse directions and which therefore are effectively 1+1-dimensional in
spacetime, except for the auxiliary fields which also depend on discretized
momentum rapidity and transverse velocity components. We reproduce the
semi-analytical results obtained previously for the Abelian regime and we
determine the nonlinear effects which occur when the instabilities have grown
such that non-Abelian interactions become important.


title:
TRAPHIC - Radiative Transfer for Smoothed Particle Hydrodynamics
  Simulations

abstract:
  We present TRAPHIC, a novel radiative transfer scheme for Smoothed Particle
Hydrodynamics (SPH) simulations. TRAPHIC is designed for use in simulations
exhibiting a wide dynamic range in physical length scales and containing a
large number of light sources. It is adaptive both in space and in angle and
can be employed for application on distributed memory machines. The commonly
encountered computationally expensive scaling with the number of light sources
in the simulation is avoided by introducing a source merging procedure. The
(time-dependent) radiative transfer equation is solved by tracing individual
photon packets in an explicitly photon-conserving manner directly on the
unstructured grid traced out by the set of SPH particles. To accomplish
directed transport of radiation despite the irregular spatial distribution of
the SPH particles, photons are guided inside cones. We present and test a
parallel numerical implementation of TRAPHIC in the SPH code GADGET-2,
specified for the transport of mono-chromatic hydrogen-ionizing radiation. The
results of the tests are in excellent agreement with both analytic solutions
and results obtained with other state-of-the-art radiative transfer codes.


title: Strong-Field Electrodynamics

abstract:
  Strong-Field Electrodynamics (SFE) is Maxwell theory with a certain
Lorentz-covariant Ohm's law which uses only the electromagnetic degrees of
freedom. We show that SFE is {\it semi-dissipative}: while the dissipation rate
of the electromagnetic energy is non-negative, it can be exactly zero for
non-trivial electromagnetic fields.
  It appears that SFE is well-defined for arbitrary electromagnetic fields. It
should be possible to calculate the dissipative pulsar magnetosphere and
resolve the magnetic separatrix using SFE.
  We show that SFE reduces to Force-Free Electrodynamics (FFE) in the large
conductivity limit. In the regions where the ideal FFE 4-current is space-like,
SFE predicts small dissipative corrections. In the regions where the ideal FFE
4-current is time-like, SFE predicts a zero correction. This indicates that
bright pulsars radiate primarily from the magnetic separatrix.


title:
Numerical Simulations of a Spherically Symmetric Yang-Mills system on a
  de Sitter Manifold

abstract:
  In this paper we discuss the dynamics of the cosmological Bartnick-McKinnon
analogue with $n=1$ and $\Lambda=\Lambda_{reg}(n)$ . We derive boundary
conditions from energy considerations. Numerical simulations are carried out to
show the existence of a non-stationary solution.


title:
Group space scan of flavor symmetries for nearly tribimaximal lepton
  mixing

abstract:
  We present a systematic group space scan of discrete Abelian flavor
symmetries for lepton mass models that produce nearly tribimaximal lepton
mixing. In our models, small neutrino masses are generated by the type-I seesaw
mechanism. The lepton mass matrices emerge from higher-dimension operators via
the Froggatt-Nielsen mechanism and are predicted as powers of a single
expansion parameter \epsilon that is of the order of the Cabibbo angle
\theta_C\simeq 0.2. We focus on solutions that can give close to tribimaximal
lepton mixing with a very small reactor angle \theta_{13}\approx 0 and find
several thousand explicit such models that provide an excellent fit to current
neutrino data. The models are rather general in the sense that large leptonic
mixings can come from the charged leptons and/or neutrinos. Moreover, in the
neutrino sector, both left- and right-handed neutrinos can mix maximally. We
also find a new relation \theta_{13}\lesssim\epsilon^3 for the reactor angle
and a new sum rule \theta_{23}\approx\pi/4+\epsilon/\sqrt{2} for the
atmospheric angle, allowing the models to be tested in future neutrino
oscillation experiments.


title:
Letter for the pressure effects on the electrostatic polarizability and
  dispersive binding of off-center polarons in ionic and molecular systems

abstract:
  The question is raised about the pressure effects on the polarizability and
dispersive binding in ionic and molecular systems. As an example we take the
effect of hydrostatic pressure on the energy gap of phonon-coupled two-level
systems. Assuming a positive pressure coefficient for the gap, we predict a
gradual transition from small vibronic polarons to large polarons as the
pressure is increased at constant coupling energy of a two-level system.
Concomitantly, the universal dispersive binding degrades from strong at low
pressure to weak at high pressure as the system evolves from soft condensed
matter to hard condensed matter. Implications are discussed on the development
of stellar substance at the early stages of the Universe.


title:
Differentiable Conjugacy of Anosov Diffeomorphisms on Three Dimensional
  Torus

abstract:
  We consider two C^2 Anosov diffeomorphisms in a C^1 neighborhood of a linear
hyperbolic automorphism of three dimensional torus with real spectrum. We prove
that they are C^1+ conjugate if and only if the differentials of the return
maps at corresponding periodic points have the same eigenvalues.


title: Silicon-based nanochannel glucose sensor

abstract:
  Silicon nanochannel biological field effect transistors have been developed
for glucose detection. The device is nanofabricated from a silicon-on-insulator
wafer with a top-down approach and surface functionalized with glucose oxidase.
The differential conductance of silicon nanowires, tuned with source-drain bias
voltage, is demonstrated to be sensitive to the biocatalyzed oxidation of
glucose. The glucose biosensor response is linear in the 0.5-8 mM concentration
range with 3-5 min response time. This silicon nanochannel-based glucose
biosensor technology offers the possibility of high density, high quality
glucose biosensor integration with silicon-based circuitry.


title: Parameterized Algorithms for Partial Cover Problems

abstract:
  Covering problems are fundamental classical problems in optimization,
computer science and complexity theory. Typically an input to these problems is
a family of sets over a finite universe and the goal is to cover the elements
of the universe with as few sets of the family as possible.
  The variations of covering problems include well known problems like Set
Cover, Vertex Cover, Dominating Set and Facility Location to name a few.
Recently there has been a lot of study on partial covering problems, a natural
generalization of covering problems. Here, the goal is not to cover all the
elements but to cover the specified number of elements with the minimum number
of sets.
  In this paper we study partial covering problems in graphs in the realm of
parameterized complexity. Classical (non-partial) version of all these problems
have been intensively studied in planar graphs and in graphs excluding a fixed
graph $H$ as a minor. However, the techniques developed for parameterized
version of non-partial covering problems cannot be applied directly to their
partial counterparts. The approach we use, to show that various partial
covering problems are fixed parameter tractable on planar graphs, graphs of
bounded local treewidth and graph excluding some graph as a minor, is quite
different from previously known techniques. The main idea behind our approach
is the concept of implicit branching. We find implicit branching technique to
be interesting on its own and believe that it can be used for some other
problems.


title: The Globular Cluster Systems around NGC 3311 and NGC 3309

abstract:
  We present extensive new photometry in (g',i') of the large globular cluster
(GC) system around NGC 3311, the central cD galaxy in the Hydra cluster. Our
GMOS data cover a 5.5' field of view and reach a limiting magnitude i' = 26,
about 0.5 magnitude fainter than the turnover point of the GC luminosity
function. We find that NGC 3311 has a huge population of ~16, 000 GCs, closely
similar to the prototypical high specific frequency Virgo giant M87. The
color-magnitude distribution shows that the metal-poor blue GC sequence and the
metal-richer red sequence are both present, with nearly equal numbers of
clusters. Bimodal fits to the color distributions confirm that the blue
sequence shows the same trend of progressively increasing metallicity with GC
mass that has previously been found in many other large galaxies; the
correlation we find corresponds to a scaling of GC metallicity with mass of Z ~
M^0.6 . By contrast, the red sequence shows no change of mean metallicity with
mass, but it shows an upward extension to much higher than normal luminosity
into the UCD-like range, strengthening the potential connections between
massive GCs and UCDs. The GC luminosity function, which we measure down to the
turnover point at M_I = -8.4, also has a normal form like those in other giant
ellipticals. Within the Hydra field, another giant elliptical NGC 3309 is
sitting just 100" from the cD NGC 3311. We use our data to solve simultaneously
for the spatial structure and total GC populations of both galaxies at once.
Their specific frequencies are S_N (NGC 3311) = 12.5 +/- 1.5 and S_N (NGC 3309)
= 0.6 +/-0.4. NGC 3311 is completely dominant and entirely comparable with
other cD-type systems such as M87 in Virgo.


title:
Dark Matter Capture in the First Stars: a Power Source and Limit on
  Stellar Mass

abstract:
  The annihilation of weakly interacting massive particles can provide an
important heat source for the first (Pop. III) stars, potentially leading to a
new phase of stellar evolution known as a "Dark Star". When dark matter (DM)
capture via scattering off of baryons is included, the luminosity from DM
annihilation may dominate over the luminosity due to fusion, depending on the
DM density and scattering cross-section. The influx of DM due to capture may
thus prolong the lifetime of the Dark Stars. Comparison of DM luminosity with
the Eddington luminosity for the star may constrain the stellar mass of zero
metallicity stars; in this case DM will uniquely determine the mass of the
first stars. Alternatively, if sufficiently massive Pop. III stars are found,
they might be used to bound dark matter properties.


title:
Fundamental constants and their variability in theories of High Energy
  Physics

abstract:
  The Standard Model of particle physics and the theory of General Relativity
(GR) currently provide a good description of almost all phenomena of particle
physics and gravitation that have received controlled experimental tests.
However, the Standard Model contains many a priori variable parameters whose
values, and whose apparent (near-)constancy, have yet to receive a convincing
theoretical explanation. At the same time, GR may now require to be extended or
altered at the largest length scales, to account for the recent apparent
accelerated cosmological expansion. In this introductory review I present
theoretical aspects of the search for explanations of the values and possible
variations of fundamental ``constants'', focusing on the possibility of
unification of interactions. I also relate cosmological variations to
modifications of gravity both locally and cosmologically.

categories: physics.atom-ph astro-ph gr-qc hep-ph hep-th physics.gen-ph


title:
Dark matter content and internal dynamics of NGC 4697: NMAGIC particle
  models from slit data and planetary nebulae velocities

abstract:
  We present a dynamical study of NGC 4697, an almost edge-on,
intermediate-luminosity, E4 elliptical galaxy, combining new surface brightness
photometry, new as well as published long-slit absorption line kinematic data,
and published planetary nebulae (PNe) velocity data. The combined kinematic
data set extends out to ~= 5' ~= 4.5 R_e and allows us to probe the galaxy's
outer halo. For the first time, we model such a dataset with the new and
flexible Chi^2-made-to-measure particle code NMAGIC. We extend NMAGIC to
include seeing effects, introduce an efficient scheme to estimate the
mass-to-light ratio, and incorporate a maximum likelihood technique to account
for discrete velocity measurements. For modelling the PNe kinematics we use
line-of-sight velocities and velocity dispersions computed on two different
spatial grids, and we also use the individual velocity measurements with the
likelihood method, in order to make sure that our results are not biased by the
way we treat the PNe measurements. We generate axisymmetric self-consistent
models as well models including various dark matter halos. These models fit all
the mean velocity and velocity dispersion data with Chi^2/N<1, both in the case
with only luminous matter and in potentials including quite massive halos. The
likelihood analysis together with the velocity histograms suggest that models
with low density halos such that the circular velocity v_c ~< 200 km/s at R_e
are not consistent with the data. A range of massive halos with v_c ~= 250 km/s
at 5R_e fit the PN data best. To derive stronger results would require PN
velocities at even larger radii. The best fitting models are slightly radially
anisotropic; the anisotropy parameter beta ~= 0.3 at the center, increasing to
beta ~= 0.5 at radii >~ 2R_e.


title:
SKA Key science project: Radio observations of cosmic reionization and
  first light

abstract:
  I update the SKA key science program (KSP) on first light and cosmic
reionization. The KSP has two themes: (i) Using the 21cm line of neutral
hydrogen as the most direct probe into the evolution of the neutral
intergalactic medium during cosmic reionization. Such HI 21cm studies are
potentially the most important new window on cosmology since the discovery of
the CMB. (ii) Observing the gas, dust, star formation, and dynamics, of the
first galaxies and AGN. Observations at cm and mm wavelengths, provide an
unobscured view of galaxy formation within 1 Gyr of the Big Bang, and are an
ideal complement to the study of stars, ionized gas, and AGN done using near-IR
telescopes. I summarize HI 21cm signals, challenges, and telescopes under
construction. I also discuss the prospects for studying the pre-galactic
medium, prior to first light, using a low frequency telescope on the Moon. I
then review the current status of mm and cm observations of the most known
distant galaxies (z > 6). I make the simple argument that even a 10% SKA-high
demonstrator will have a profound impact on the study of the first galaxies. In
particular, extending the SKA to the 'natural' atmospheric limit (set by the
O_2 line) of 45 GHz, increases the effective sensitivity to thermal emission by
another factor four.


title: Cosmology With A Dark Refraction Index

abstract:
  We review Gordon's optical metric and the transport equations for the
amplitude and polarization of a geometrical optics wave traveling in a gravity
field. We apply the theory to the FLRW cosmologies by associating a refraction
index with the cosmic fluid. We then derive an expression for the accumulated
effect of a refraction index on the distance redshift relations and fit the
Hubble curve of current supernova observations with a non-accelerating
cosmological model. We also show that some observational effects caused by
inhomogeneities, e.g. the Sachs-Wolfe effect, can be interpreted as being
caused by an effective index of refraction, and hence this theory could extend
to other speed of light communications such as gravitational radiation and
neutrino fluxes.


title: The X-Ray Origin of Herbig AeBe Systems: New Insights

abstract:
  We present a statistical study of the X-Ray emission toward 22 Herbig AeBe
stars using the Chandra archive. We probe the origin of the X-Rays toward
Herbig stars: are they intrinsic? This question is addressed by correlations
between the physical stellar properties and the X-Ray emission. There is a weak
correlation between the continuum radio emission at lambda = 3.6cm and Lx,
which suggests that the X-Ray emission depends upon the source. On the other
hand, no correlation was found with the stellar rotational period, but that
only excludes solar-like magnetic activity as the origin of the X-Rays. Most
importantly, the X-Ray luminosity of Herbig AeBe stars have a different
distribution than T Tauri stars, suggesting X-Ray emission from an unseen late
type star companion can be ruled out with an 80% confidence level. This implies
that the Herbig AeBe stars must have magnetic activity. In addition, we report
the observation of five sources for the first time, three detections.


title: Helical CR Structures and Sub-Riemannian Geodesics

abstract:
  A helical CR structure is a decomposition of a real Euclidean space into an
even-dimensional horizontal subspace and its orthogonal vertical complement,
together with an almost complex structure on the horizontal space and a marked
vector in the vertical space. We prove an equivalence between such structures
and step two Carnot groups equipped with a distinguished normal geodesic, and
also between such structures and smooth real curves whose derivatives have
constant Euclidean norm. As a consequence, we relate step two Carnot groups
equipped with sub-Riemannian geodesics with this family of curves. The
restriction to the unit circle of certain planar homogeneous polynomial
mappings gives an instructive class of examples. We describe these examples in
detail.


title: The Jupiter Twin HD 154345b

abstract:
  We announce the discovery of a twin of Jupiter orbiting the slightly
metal-poor ([Fe/H] = -0.1) nearby (d = 18 pc) G8 dwarf HD 154345. This planet
has a minimum mass of 0.95 Jupiter masses and a 9.2 year, circular orbit with
radius 4.2 AU. There is currently little or no evidence for other planets in
the system, but smaller or exterior planets cannot yet be ruled out. We also
detect a ~ 9-year activity cycle in this star photometrically and in
chromospheric emission. We rule out activity cycles as the source of the radial
velocity variations by comparison with other cycling late-G dwarfs.


title:
Spitzer IRS Observations of Disks around Brown Dwarfs in the TW Hydra
  Association

abstract:
  Using SpeX at the NASA Infrared Telescope Facility and the Spitzer Infrared
Spectrograph, we have obtained infrared spectra from 0.7 to 30um for three
young brown dwarfs in the TW Hydra Association (~10 Myr), 2M J1207-3932, 2M
J1139-3159, and SS J1102-3431. The spectral energy distribution for 2M
J1139-3159 is consistent with a stellar photosphere for the entire wavelength
range of our data while the other two objects exhibit significant excess
emission at >5um. We are able to reproduce the excess emission from each brown
dwarf using our models of irradiated accretion disks. According to our model
fits, both disks have experienced a high degree of dust settling. We also find
that silicate emission at 10 and 20um is absent from the spectra of these
disks, indicating that grains in the upper disk layers have grown to sizes
larger than ~5um. Both of these characteristics are consistent with previous
observations of decreasing silicate emission with lower stellar masses and
older ages. These trends suggest that either 1) the growth of dust grains, and
perhaps planetesimal formation, occurs faster in disks around brown dwarfs than
in disks around stars, or 2) the radii of the mid-IR-emitting regions of disks
are smaller for brown dwarfs than for stars, and grains grow faster at smaller
disk radii. Finally, we note the possible detection of an unexplained emission
feature near 14um in the spectra of both of the disk-bearing brown dwarfs.


title: Artin HNN-extensions virtually embed in Artin groups

abstract:
  An Artin HNN-extension is an HNN-extension of an Artin group in which the
stable letter conjugates a pair of suitably chosen subsets of the standard
generating set. We show that some finite index subgroup of an Artin
HNN-extension embeds in an Artin group. We also obtain an analogous result for
Coxeter groups.


title: Lower bounds on entanglement measures from incomplete information

abstract:
  How can we quantify the entanglement in a quantum state, if only the
expectation value of a single observable is given? This question is of great
interest for the analysis of entanglement in experiments, since in many
multiparticle experiments the state is not completely known. We present several
results concerning this problem by considering the estimation of entanglement
measures via Legendre transforms. First, we present a simple algorithm for the
estimation of the concurrence and extensions thereof. Second, we derive an
analytical approach to estimate the geometric measure of entanglement, if the
diagonal elements of the quantum state in a certain basis are known. Finally,
we compare our bounds with exact values and other estimation methods for
entanglement measures.


title: Magnetism in Disordered Graphene and Irradiated Graphite

abstract:
  The magnetic properties of disordered graphene and irradiated graphite are
systematically studied using a combination of mean-field Hubbard model and
first-principles calculations. By considering large-scale disordered models of
graphene, I conclude that only single-atom defects can induce ferromagnetism in
graphene-based materials. The preserved stacking order of graphene layers is
shown to be another necessary condition for achieving a finite net magnetic
moment of irradiated graphite. Ab initio calculations of hydrogen binding and
diffusion and of interstitial-vacancy recombination further confirm the crucial
role of stacking order in $\pi$-electron ferromagnetism of proton-bombarded
graphite.

categories: cond-mat.mtrl-sci cond-mat.dis-nn cond-mat.mes-hall cond-mat.str-el


title: Tests of Lorentz symmetry using antihydrogen

abstract:
  Signals of CPT and Lorentz violation are possible in the context of
spectroscopy using hydrogen and antihydrogen. We apply the Standard-Model
Extension, a broad framework for Lorentz breaking in physics, to various
transitions in the hydrogen and antihydrogen spectra. The results show an
unsuppressed effect in the transition between the upper two hyperfine sublevels
of the ground state of these systems. We also discuss related tests in Penning
traps, and recent work on Lorentz violation in curved spacetime.


title: Midlife Crises in Dwarf Galaxies in the NGC 5353/4 Group

abstract:
  This third paper in a series about the dwarf galaxy populations in groups
within the Local Supercluster concerns the intermediate mass (2.1 x 10^13
solar) NGC 5353/4 Group with a core dominated by S0 systems and a periphery of
mostly spiral systems. Dwarf galaxies are strongly concentrated toward the
core. The mass to light ratio M/L_R=105 in solar units is a factor 3 lower than
for the two groups studied earlier in the series. The properties of the group
suggest it is much less dynamically evolved than those two groups of early type
galaxies. By comparison, the NGC 5353/4 Group lacks superluminous systems but
has a large fraction of intermediate luminosity galaxies; or equivalently, a
luminosity function with a flatter faint end slope. The luminosity function for
the NGC 5353/4 Group should steepen as the intermediate luminosity galaxies
merge. Evidence for the ongoing collapse of the group is provided by the
unusually large incidence of star formation activity in small galaxies with
early morphological types. The pattern in the distribution of galaxies with
activity suggests a succession of infall events. Residual gas in dwarfs that
enter the group is used up in sputtering events. The resolution of midlife
crises is exhaustion.


title:
Characterising through Erasing: A Theoretical Framework for Representing
  Documents Inspired by Quantum Theory

abstract:
  The problem of representing text documents within an Information Retrieval
system is formulated as an analogy to the problem of representing the quantum
states of a physical system. Lexical measurements of text are proposed as a way
of representing documents which are akin to physical measurements on quantum
states. Consequently, the representation of the text is only known after
measurements have been made, and because the process of measuring may destroy
parts of the text, the document is characterised through erasure. The
mathematical foundations of such a quantum representation of text are provided
in this position paper as a starting point for indexing and retrieval within a
``quantum like'' Information Retrieval system.


title: On the complexity of proper holomorphic mappings between balls

abstract:
  We make several new contributions to the study of proper holomorphic mappings
between balls. Our results include a degree estimate for rational proper maps,
a new gap phenomenon for convex families of arbitrary proper maps, and an
interesting result about inverse images.


title: Temperature dependent magnetization dynamics of magnetic nanoparticles

abstract:
  Recent experimental and theoretical studies show that the switching behavior
of magnetic nanoparticles can be well controlled by external time-dependent
magnetic fields. In this work, we inspect theoretically the influence of the
temperature and the magnetic anisotropy on the spin-dynamics and the switching
properties of single domain magnetic nanoparticles (Stoner-particles). Our
theoretical tools are the Landau-Lifshitz-Gilbert equation extended as to deal
with finite temperatures within a Langevine framework. Physical quantities of
interest are the minimum field amplitudes required for switching and the
corresponding reversal times of the nanoparticle's magnetic moment. In
particular, we contrast the cases of static and time-dependent external fields
and analyze the influence of damping for a uniaxial and a cubic anisotropy.


title: Radial distribution of RNA genome packaged inside spherical viruses

abstract:
  The problem of RNA genomes packaged inside spherical viruses is studied. The
viral capsid is modeled as a hollowed sphere. The attraction between RNA
molecules and the inner viral capsid is assumed to be non-specific and occurs
at the inner capsid surface only. For small capsid attraction, it is found that
monomer concentration of RNA molecules is maximum at the center of the capsid
to maximize their configurational entropy. For stronger capsid attraction, RNA
concentration peaks at some distance near the capsid. In the latter case, the
competition between the branching of RNA secondary struture and its adsorption
to the inner capsid results in the formation of a dense layer of RNA near
capsid surface. The layer thickness is a slowly varying (logarithmic) function
of the capsid inner radius. Consequently, for immediate strength of RNA-capsid
interaction, the amount of RNA packaged inside a virus is proportional to the
capsid {\em area} (or the number of proteins) instead of its volume. The
numerical profiles describe reasonably well the experimentally observed RNA
nucleotide concentration profiles of various viruses.


title:
On the role of the WNH phase in the evolution of very massive stars:
  Enabling the LBV instability with feedback

abstract:
  (abridged) We propose the new designation ``WNH'' for luminous Wolf-Rayet
(WR) stars of the nitrogen sequence with H in their spectra. These are commonly
called WNL stars (e.g., WN7h), but this new shorthand avoids confusion because
there are late-type WN stars without H and early-type WN stars with H. Clearly
differentiating WNH stars from H-free WN stars is critical when discussing
progenitors of Type Ib/c SNe and GRBs -- the massive WNH stars are not likely
SN progenitors, and are distinct from core-He burning WR stars. We show that
the masses of WNH stars are systematically higher than H-poor WR stars (both WN
and WC), with little overlap, while H mass fractions of luminous WNH stars
exceed those of LBVs. We favor the interpretation that the most luminous WNH
stars are still core-H burning, pre-LBVs. While on the main sequence, a star's
mass is reduced due to winds while its luminosity slowly rises, so the star
increases its Eddington factor and mass-loss rate, pushing it even closer to
the Eddington limit. With this feedback, observed masses and mass-loss rates of
WNH stars are a natural outcome near the end of core-H burning. Feedback from
the strong WNH wind itself then enables the instability seen later as an LBV.
Steadily climbing mass-loss rates also explain continuity in spectral traits
from O3 V to O3 If* to WNH.


title: Late-time observations of SN2006gy: Still Going Strong

abstract:
  Owing to its extremely high luminosity and long duration, SN2006gy radiated
more energy in visual light than any other known SN. Two hypotheses to explain
its high luminosity -- that it was powered by shock interaction with CSM as
implied by its Type IIn spectrum, or that it was fueled by radioactive decay
from a large mass of 56Ni synthesized in a pair-instability SN -- predicted
different late-time properties. Here we present observations of SN2006gy
obtained more than a year after discovery. We were unable to detect it at
visual wavelengths, but clear near-IR K and H-band detections show that it is
still at least as luminous as the peak of a normal SN II. We also present
spectra giving an upper limit to the late-time Ha luminosity of about 1e39
erg/s. Based on the weak late-time Ha, X-ray, and radio emission, combined with
the difficulty of explaining the shift to IR wavelengths, we can rule out
ongoing CSM interaction as the primary late-time power source. Instead, we
propose that the evolution of SN2006gy is consistent with one of two possible
scenarios: (1) A pair-instability SN plus modest CSM interaction, where the
radioactive decay luminosity shifts to the IR because of dust formation. (2) An
IR echo, where radiation emitted during peak luminosity heats a pre-existing
dust shell at radii near 1 light year, requiring the progenitor star to have
ejected another 10 Msun shell about 1500 yr before the SN.


title: Episodic Mass Loss and Pre-SN Circumstellar Envelopes

abstract:
  I discuss observational clues concerning episodic mass-loss properties of
massive stars in the time before the final supernova explosion. In particular,
I will focus on the mounting evidence that LBVs and related stars are
candidates for supernova progenitors, even though current paradigms place them
at the end of core-H burning. Namely, conditions in the immediate circumstellar
environment within a few 10$^2$ AU of Type IIn supernovae require very high
progenitor mass-loss rates. Those rates are so high that the only known stars
that come close are LBVs during rare giant eruptions. I will highlight evidence
from observations of some recent extraordinary supernovae suggesting that
explosive or episodic mass loss (a.k.a. LBV eruptions like the 19th century
eruption of Eta Car) occur in the 5-10 years immediately preceding the SN.
Finally, I will discuss some implications for stellar evolution from these SNe,
the most important of which is the observational fact that the most massive
stars can indeed make it to the ends of their lives with substantial H
envelopes intact, even at Solar metallicity.


title:
Superscaling Predictions for Neutral Current Quasielastic
  Neutrino-Nucleus Scattering

abstract:
  The application of superscaling ideas to predict neutral-current (NC)
quasielastic (QE) neutrino cross sections is investigated. Results obtained
within the relativistic impulse approximation (RIA) using the same relativistic
mean field potential (RMF) for both initial and final nucleons -- a model that
reproduces the experimental (e,e') scaling function -- are used to illustrate
the ideas involved. While NC reactions are not so well suited for scaling
analyses, to a large extent the RIA-RMF predictions do exhibit superscaling.
Independence of the scaled response on the nuclear species is very well
fulfilled. The RIA-RMF NC superscaling function is in good agreement with the
experimental (e,e') one. The idea that electroweak processes can be described
with a universal scaling function, provided that mild restrictions on the
kinematics are assumed, is shown to be valid.


title:
Eta Carinae and Nebulae Around Massive Stars: Similarities to Planetary
  Nebulae?

abstract:
  I discuss some observational properties of aspherical nebulae around massive
stars, and conclusions inferred for how they may have formed. Whether or not
these ideas are applicable to the shaping of planetary nebulae is uncertain,
but the observed similarities between some PNe and bipolar nebulae around
massive stars is compelling. In the well-observed case of Eta Carinae, several
lines of observational evidence point to a scenario where the shape of its
bipolar nebula resulted from an intrinsically bipolar explosive ejection event
rather than an interacting winds scenario occurring after ejection from teh
star. A similar conclusion has been inferred for some planetary nebulae. I also
briefly mention bipolar nebulae around some other massive stars, such as the
progenitor of SN 1987A and related blue supergiants.


title: Information flow between stock indices

abstract:
  Using transfer entropy, we observed the strength and direction of information
flow between stock indices. We uncovered that the biggest source of information
flow is America. In contrast, the Asia/Pacific region the biggest is receives
the most information. According to the minimum spanning tree, the GSPC is
located at the focal point of the information source for world stock markets.


title:
Violation of the Zeroth Law of Thermodynamics in Systems with Negative
  Specific Heat

abstract:
  We show that systems with negative specific heat can violate the zeroth law
of thermodynamics. By both numerical simulations and by using exact expressions
for free energy and microcanonical entropy it is shown that if two systems with
the same intensive parameters but with negative specific heat are thermally
coupled, they undergo a process in which the total entropy increases
irreversibly. The final equilibrium is such that two phases appear, that is,
the subsystems have different magnetizations and internal energies at
temperatures which are equal in both systems, but that can be different from
the initial temperature.


title: Detonation along laser generated micropinch for fast ignition

abstract:
  The proposed fast ignition of highly compressed deuterium-tritium (DT)
targets by petawatt lasers requires energy of about 100kJ. To lower the power
of the laser, it is proposed to accomplish fast ignition with two lasers, one
with lower power in the infrared, and a second one with high power in the
visible to ultraviolet region. The infrared laser of lower power shall by its
radiation pressure drive a large current in a less than solid density plasma
placed inside a capillary, while the second high power-shorter wave
length-laser shall ignite at one end of the capillary a magnetic field
supported thermonuclear detonation wave in a blanket made from solid DT along
the outer surface of the capillary. The other end of the capillary, together
with its DT blanket, is stuck in the DT target, where following the compression
of the target the detonation wave ignites the target.


title:
Bifurcation analysis of a normal form for excitable media: Are stable
  dynamical alternans on a ring possible?

abstract:
  We present a bifurcation analysis of a normal form for travelling waves in
one-dimensional excitable media. The normal form which has been recently
proposed on phenomenological grounds is given in form of a differential delay
equation. The normal form exhibits a symmetry preserving Hopf bifurcation which
may coalesce with a saddle-node in a Bogdanov-Takens point, and a symmetry
breaking spatially inhomogeneous pitchfork bifurcation. We study here the Hopf
bifurcation for the propagation of a single pulse in a ring by means of a
center manifold reduction, and for a wave train by means of a multiscale
analysis leading to a real Ginzburg-Landau equation as the corresponding
amplitude equation. Both, the center manifold reduction and the multiscale
analysis show that the Hopf bifurcation is always subcritical independent of
the parameters. This may have links to cardiac alternans which have so far been
believed to be stable oscillations emanating from a supercritical bifurcation.
We discuss the implications for cardiac alternans and revisit the instability
in some excitable media where the oscillations had been believed to be stable.
In particular, we show that our condition for the onset of the Hopf bifurcation
coincides with the well known restitution condition for cardiac alternans.


title: Hyperdiffusion as a Mechanism for Solar Coronal Heating

abstract:
  A theory for the heating of coronal magnetic flux ropes is developed. The
dissipated magnetic energy has two distinct contributions: (1) energy injected
into the corona as a result of granule-scale, random footpoint motions, and (2)
energy from the large-scale, nonpotential magnetic field of the flux rope. The
second type of dissipation can be described in term of hyperdiffusion, a type
of magnetic diffusion in which the helicity of the mean magnetic field is
conserved. The associated heating rate depends on the gradient of the torsion
parameter of the mean magnetic field. A simple model of an active region
containing a coronal flux rope is constructed. We find that the temperature and
density on the axis of the flux rope are lower than in the local surroundings,
consistent with observations of coronal cavities. The model requires that the
magnetic field in the flux rope is stochastic in nature, with a perpendicular
length scale of the magnetic fluctuations of order 1000 km.


title:
Shear transformation zone analysis of shear reversal during granular
  flow

abstract:
  Experimental measurements of the onset of granular flow are directly compared
to predictions of the "shear transformation zone" (STZ) theory of amorphous
plasticity. The STZ equations make it possible, on a coarse grained level, to
incorporate the anisotropy of the particle contact network and its dynamic
evolution including changes in the contact network direction under shear
reversal. The STZ theory and experiment show qualitative agreement in the
transient and steady state shear forces and velocity profiles during the start
of shear and shear reversal.

categories: cond-mat.stat-mech cond-mat.dis-nn cond-mat.mtrl-sci cond-mat.soft


title: A Comment or two on Holographic Dark Energy

abstract:
  It has, quite recently, become fashionable to study a certain class of
holographic-inspired models for the dark energy. These investigations have,
indeed, managed to make some significant advances towards explaining the
empirical data. Nonetheless, surprisingly little thought has been given to
conceptual issues such as the composition and the very nature of the implicated
energy source. In the current discourse, we attempt to fill this gap by the way
of some speculative yet logically self-consistent arguments. Our construction
takes us along a path that begins with an entanglement entropy and ends up at a
Hubble-sized gas of exotic particles. Moreover, our interpretation of the dark
energy turns out to be suggestive of a natural resolution to the
cosmic-coincidence problem.


title: ARQ for Network Coding

abstract:
  A new coding and queue management algorithm is proposed for communication
networks that employ linear network coding. The algorithm has the feature that
the encoding process is truly online, as opposed to a block-by-block approach.
The setup assumes a packet erasure broadcast channel with stochastic arrivals
and full feedback, but the proposed scheme is potentially applicable to more
general lossy networks with link-by-link feedback. The algorithm guarantees
that the physical queue size at the sender tracks the backlog in degrees of
freedom (also called the virtual queue size). The new notion of a node "seeing"
a packet is introduced. In terms of this idea, our algorithm may be viewed as a
natural extension of ARQ schemes to coded networks. Our approach, known as the
drop-when-seen algorithm, is compared with a baseline queuing approach called
drop-when-decoded. It is shown that the expected queue size for our approach is
$O(\frac1{1-\rho})$ as opposed to $\Omega(\frac1{(1-\rho)^2})$ for the baseline
approach, where $\rho$ is the load factor.


title:
FMR induced Josephson Current in a
  Superconductor/Ferromagnet/Superconductor Junction

abstract:
  We propose the phase dynamics induced by spin waves in a
superconductor/ferromagnet/superconductor (SC/FM/SC) Josephson junction. The
resistively shunted junction (RSJ) model, which describes the dynamics of
superconducting phase difference, is extended to include the spin wave
excitation by ferromagnetic resonance (FMR) using the gauge invariant phase
difference between two s-wave superconductors. The current-voltage
characteristics show step structures when the magnetization in FM is driven by
tuning the microwave frequency to FMR in the SC/FM/SC junction. The result
presents a new route to observe the spin wave excitation using the Josephson
effect.


title: Nanoscale field effect transistor for biomolecular signal amplification

abstract:
  We report amplification of biomolecular recognition signal in
lithographically defined silicon nanochannel devices. The devices are
configured as field effect transistors (FET) in the reversed source-drain bias
region. The measurement of the differential conductance of the nanowire
channels in the FET allows sensitive detection of changes in the surface
potential due to biomolecular binding. Narrower silicon channels demonstrate
higher sensitivity to binding due to increased surface-to-volume ratio. The
operation of the device in the negative source-drain region demonstrates signal
amplification. The equivalence between protein binding and change in the
surface potential is described.

categories: physics.bio-ph cond-mat.mtrl-sci cond-mat.other physics.chem-ph


title:
Thermodynamic similarity between the noncommutative Schwarzschild black
  hole and the Reissner-Nordstr\"om black hole

abstract:
  We study thermodynamic quantities and examine the stability of a black hole
in a cavity inspired by the noncommutative geometry. It turns out that
thermodynamic behavior of the noncommutative black hole is analogous to that of
the Reissner-Nordstr\"om black hole in the near extremal limit. Moreover, we
identify the noncommutative parameter with the squared electric charge with
some constants.


title: Meta-stable SUSY Breaking Model in Supergravity

abstract:
  We analyze a supersymmetry (SUSY) breaking model proposed by Intriligator,
Seiberg and Shih in a supergravity (SUGRA) framework. This is a simple and
natural setup which demands neither extra superpotential interactions nor an
additional gauge symmetry. In the SUGRA setup, the U(1)R symmetry is explicitly
broken by the constant term in the superpotential, and pseudo-moduli field
naturally takes non-zero vacuum expectation value through a vanishing
cosmological constant condition. Sfermions tend to be heavier than gauginos,
and the strong-coupling scale is determined once a ratio of sfermion to gaugino
masses is fixed.


title:
Accretion to Magnetized Stars through the Rayleigh-Taylor Instability:
  Global Three-Dimensional Simulations

abstract:
  We present results of 3D simulations of MHD instabilities at the accretion
disk-magnetosphere boundary. The instability is Rayleigh-Taylor, and develops
for a fairly broad range of accretion rates and stellar rotation rates and
magnetic fields. It manifests itself in the form of tall, thin tongues of
plasma that penetrate the magnetosphere in the equatorial plane. The shape and
number of the tongues changes with time on the inner-disk dynamical timescale.
In contrast with funnel flows, which deposit matter mainly in the polar region,
the tongues deposit matter much closer to the stellar equator. The instability
appears for relatively small misalignment angles, $\Theta\lesssim30^\circ$,
between the star's rotation and magnetic axes, and is associated with higher
accretion rates. The hot spots and light curves during accretion through
instability are generally much more chaotic than during stable accretion. The
unstable state of accretion has possible implications for quasi-periodic
oscillations and intermittent pulsations from accreting systems, as well as
planet migration.


title:
Doping and energy dependent microwave conductivity of kinetic energy
  driven superconductors with extended impurities

abstract:
  Within the framework of the kinetic energy driven superconducting mechanism,
the effect of the extended impurity scatterers on the quasiparticle transport
of cuprate superconductors in the superconducting state is studied based on the
nodal approximation of the quasiparticle excitations and scattering processes.
It is shown that there is a cusplike shape of the energy dependent microwave
conductivity spectrum. At low temperatures, the microwave conductivity
increases linearly with increasing temperatures, and reaches a maximum at
intermediate temperature, then decreases with increasing temperatures at high
temperatures. In contrast with the dome shape of the doping dependent
superconducting gap parameter, the minimum microwave conductivity occurs around
the optimal doping, and then increases in both underdoped and overdoped
regimes.


title:
Spin coefficients for four-dimensional neutral metrics, and null
  geometry

abstract:
  Notation for spin coefficients for metrics of neutral signature in four
dimensions is introduced. The utility and interpretation of spin coefficients
is explored through themes in null geometry familiar from (complex) general
relativity. Four-dimensional Walker geometry is exploited to provide examples
and the generalization of the real neutral version of Pleba\~nski's (1975)
second heavenly equation to certain Walker geometries given in Law and
Matsushita [16] is extended further.


title: Evidence for biological L\'evy flights stands

abstract:
  Edwards et al. [Nature 449, 1044-1048 (2007)] revisited well-known studies
reporting power-laws in the frequency distribution of flight duration of
wandering albatrosses, and concluded that no L\'evy process could model recent
observations with higher resolution. Here we show that this re-analysis suffers
from a conceptual misunderstanding, and that the new albatross data remain
consistent with a biological L\'evy flight.


title:
Approximating the ground state of fermion system by multiple determinant
  states: matching pursuit approach

abstract:
  We present a simple and stable numerical method to approximate the ground
state of a quantum many-body system by multiple determinant states. This method
searches these determinant states one by one according to the matching pursuit
algorithm. The first determinant state is identical to that of the Hartree-Fock
theory. Calculations for two-dimensional Hubbard model serve as a
demonstration.


title: Riemann Hypothesis may be proved by induction

abstract:
  The transformations of the sum identities for generalized harmonic and
oscillatory numbers, obtained earlier in our recent report [1], enable us to
derive the new identities expressed in terms of the corresponding square roots
of x. At least one of these identities may be applied to prove the Riemann
Hypothesis by induction. Additionally using this approach, the new series for
Euler's constant gamma has been found.


title: Relationships between magnetic foot points and G-band bright structures

abstract:
  Magnetic elements are thought to be described by flux tube models, and are
well reproduced by MHD simulations. However, these simulations are only
partially constrained by observations. We observationally investigate the
relationship between G-band bright points and magnetic structures to clarify
conditions, which make magnetic structures bright in G-band. The G-band
filtergrams together with magnetograms and dopplergrams were taken for a plage
region covered by abnormal granules as well as ubiquitous G-band bright points,
using the Swedish 1-m Solar Telescope (SST) under very good seeing conditions.
High magnetic flux density regions are not necessarily associated with G-band
bright points. We refer to the observed extended areas with high magnetic flux
density as magnetic islands to separate them from magnetic elements. We
discover that G-band bright points tend to be located near the boundary of such
magnetic islands. The concentration of G-band bright points decreases with
inward distance from the boundary of the magnetic islands. Moreover, G-band
bright points are preferentially located where magnetic flux density is higher,
given the same distance from the boundary. There are some bright points located
far inside the magnetic islands. Such bright points have higher minimum
magnetic flux density at the larger inward distance from the boundary.
Convective velocity is apparently reduced for such high magnetic flux density
regions regardless of whether they are populated by G-band bright points or
not. The magnetic islands are surrounded by downflows.These results suggest
that high magnetic flux density, as well as efficient heat transport from the
sides or beneath, are required to make magnetic elements bright in G-band.


title: Structured Semidefinite Representation of Some Convex Sets

abstract:
  Linear matrix Inequalities (LMIs) have had a major impact on control but
formulating a problem as an LMI is an art. Recently there is the beginnings of
a theory of which problems are in fact expressible as LMIs. For optimization
purposes it can also be useful to have "lifts" which are expressible as LMIs.
We show here that this is a much less restrictive condition and give methods
for actually constructing lifts and their LMI representation.


title: Detection of 6 K gas in Ophiuchus D

abstract:
  Cold cores in interstellar molecular clouds represent the very first phase in
star formation. The physical conditions of these objects are studied in order
to understand how molecular clouds evolve and how stellar masses are
determined. The purpose of this study is to probe conditions in the dense,
starless clump Ophichus D (Oph D). The ground-state (1(10)-1(11)) rotational
transition of ortho-H2D+ was observed with APEX towards the density peak of Oph
D. The width of the H2D+ line indicates that the kinetic temperature in the
core is about 6 K. So far, this is the most direct evidence of such cold gas in
molecular clouds. The observed H2D+ spectrum can be reproduced with a
hydrostatic model with the temperature increasing from about 6 K in the centre
to almost 10 K at the surface. The model is unstable against any increase in
the external pressure, and the core is likely to form a low-mass star. The
results suggest that an equilibrium configuration is a feasible intermediate
stage of star formation even if the larger scale structure of the cloud is
thought to be determined by turbulent fragmentation. In comparison with the
isothermal case, the inward decrease in the temperature makes smaller, i.e.
less massive, cores susceptible to externally triggered collapse.


title: Lens Mapping of Dark Matter Substructure with VSOP-2

abstract:
  Hierarchical clustering models of cold dark matter (CDM) predict that about
5% - 10% of a galaxy-sized halo with mass ~ 10^12 solar masses (M_sun) resides
in substructures (CDM subhalos) with masses <= 10^8 M_sun. To directly identify
such substructures, we propose to observe radio continuum emission from
multiply imaged QSOs using VSOP-2 with a high angular resolution.


title: Transient horizontal magnetic fields in solar plage regions

abstract:
  We report the discovery of isolated, small-scale emerging magnetic fields in
a plage region with the Solar Optical Telescope aboard Hinode.
Spectro-polarimetric observations were carried out with a cadence of 34 seconds
for the plage region located near disc center. The vector magnetic fields are
inferred by Milne-Eddington inversion. The observations reveal widespread
occurrence of transient, spatially isolated horizontal magnetic fields. The
lateral extent of the horizontal magnetic fields is comparable to the size of
photospheric granules. These horizontal magnetic fields seem to be tossed about
by upflows and downflows of the granular convection. We also report an event
that appears to be driven by the magnetic buoyancy instability. We refer to
buoyancy-driven emergence as type1 and convection-driven emergence as type2.
Although both events have magnetic field strengths of about 600 G, the filling
factor of type1 is a factor of two larger than that of type2. Our finding
suggests that the granular convection in the plage regions is characterized by
a high rate of occurrence of granular-sized transient horizontal fields.


title:
Multi-wavelength observations of Galactic hard X-ray sources discovered
  by INTEGRAL. II. The environment of the companion star

abstract:
  Context: The INTEGRAL mission has led to the discovery of a new type of
supergiant X-ray binaries (SGXBs), whose physical properties differ from those
of previously known SGXBs. Those sources are in the course of being unveiled by
means of multi-wavelength X-rays, optical, near- and mid-infrared observations,
and two classes are appearing. The first class consists of obscured persistent
SGXBs and the second is populated by the so-called supergiant fast X-ray
transients (SFXTs). Aims: We report here mid-infrared (MIR) observations of the
companion stars of twelve SGXBs from these two classes in order to assess the
contribution of the star and the material enshrouding the system to the total
emission.} Methods: We used data from observations we carried out at ESO/VLT
with VISIR, as well as archival and published data, to perform broad-band
spectral energy distributions of the companion stars and fitted them with a
combination of two black bodies representing the star and a MIR excess due to
the absorbing material enshrouding the star, if there was any. Results: We
detect a MIR excess in the emission of IGR J16318-4848, IGR J16358-4726, and
perhaps IGR J16195-4945. The other sources do not exhibit any MIR excess even
when the intrinsic absorption is very high. (abridged)


title: The conjugacy problem in right-angled Artin groups and their subgroups

abstract:
  We prove that the conjugacy problem in right-angled Artin groups (RAAGs), as
well as in a large and natural class of subgroups of RAAGs, can be solved in
linear-time. This class of subgroups contains, for instance, all graph braid
groups (i.e. fundamental groups of configuration spaces of points in graphs),
many hyperbolic groups, and it coincides with the class of fundamental groups
of ``special cube complexes'' studied independently by Haglund and Wise.


title:
Laser-fabricated porous alumina membranes (LF-PAM) for the preparation
  of metal nanodot arrays

abstract:
  We report on an efficient photonic-based method to prepare nanodot array of
functional materials, independently of the nature of the substrate.


title: Uncertainties in (E)UV model atmosphere fluxes

abstract:
  During the comparison of synthetic spectra calculated with two NLTE model
atmosphere codes, namely TMAP and TLUSTY, we encounter systematic differences
in the EUV fluxes due to the treatment of level dissolution by pressure
ionization. Systematic differences may occur due to a code-specific cutoff
frequency of the H I Lyman bound-free opacity. This is the case for TMAP and
TLUSTY. Both codes predict the same flux level at wavelengths lower than about
1500 A for stars with effective temperatures below about 30000K only, if the
same cutoff frequency is chosen.
  In the case of Sirius B, we demonstrate an uncertainty in modeling the EUV
flux reliably in order to challenge theoreticians to improve the theory of
level dissolution.
  The theory of level dissolution in high-density plasmas, which is available
for hydrogen only should be generalized to all species. Especially, the cutoff
frequencies for the bound-free opacities should be defined in order to make
predictions of UV fluxes more reliable.


title:
Multi-wavelength observations of Galactic hard X-ray sources discovered
  by INTEGRAL. I. The nature of the companion star

abstract:
  Context: The INTEGRAL hard X-ray observatory has revealed an emerging
population of highly obscured X-ray binary systems through multi-wavelength
observations. Previous studies have shown that many of these sources are
high-mass X-ray binaries hosting neutron stars orbiting around luminous and
evolved companion stars. Aims: To better understand this newly-discovered
population, we have selected a sample of sources for which an accurate
localisation is available to identify the stellar counterpart and reveal the
nature of the companion star and of the binary system. Methods: We performed an
intensive study of a sample of thirteen INTEGRAL sources, through
multi-wavelength optical to NIR photometric and spectroscopic observations,
using EMMI and SofI instruments at the ESO NTT telescope. We performed accurate
astrometry and identified candidate counterparts for which we give the optical
and NIR magnitudes. We detected many spectral lines allowing us to determine
the spectral type of the companion star. We fitted with stellar black bodies
the mid-infrared to optical spectral energy distributions of these sources.
From the spectral analysis and SED fitting we identified the nature of the
companion stars and of the binary systems. (abridged).


title: An Uneven Vacuum Energy Fluid as $\Lambda$, Dark Matter, MOND and Lens

abstract:
  Various TeVeS-inspired and f(R)-inspired theories of gravity have added an
interesting twist to the search for dark matter and vacuum energy, modifying
the landscape of astrophysics day by day. These theories can be together called
a {\bf N}on-{\bf u}niform Dark Energy fluid (a Nu-Lambda fluid or a ${\mathbf
V\Lambda}$ fluid); a common thread of these theories, according of an
up-to-date summary by HZL \cite{Halle}, is a non-uniform vector field,
describing an uneven vacuum energy fluid. The so-called "alternative" gravity
theories are in fact in the standard GR gravity framework except that the
cosmological "constant" is replaced by a non-trivial non-uniform vacuum energy,
which couples the effects of Dark Matter and Dark Energy together by a single
field. Built initially bottom-up rather than top-down as most gravity theories,
TeVeS-inspired theories are healthily rooted on empirical facts. Here I attempt
a review of some sanity checks of these fast-developing theories from galaxy
rotation curves, gravitational lensing and cosmic acceleration. I will also
discuss some theoretical aspects of the vacuum energy, and point out some
analogies with electromagnetism and the Casimir effect.


title:
Free Field Approach to Solutions of the Quantum Knizhnik-Zamolodchikov
  Equations

abstract:
  Solutions of the qKZ equation associated with the quantum affine algebra
$U_q(\hat{sl}_2)$ and its two dimensional evaluation representation are
studied. The integral formulae derived from the free field realization of
intertwining operators of $q$-Wakimoto modules are shown to coincide with those
of Tarasov and Varchenko.


title:
SYMPA, a dedicated instrument for Jovian Seismology. II. Real
  performance and first results

abstract:
  Context. Due to its great mass and its rapid formation, Jupiter has played a
crucial role in shaping the Solar System. The knowledge of its internal
structure would strongly constrain the solar system formation mechanism.
Seismology is the most efficient way to probe directly the internal structure
of giant planets. Aims. SYMPA is the first instrument dedicated to the
observations of free oscillations of Jupiter. Principles and theoretical
performance have been presented in paper I. This second paper describes the
data processing method, the real instrumental performance and presents the
first results of a Jovian observation run, lead in 2005 at Teide Observatory.
Methods. SYMPA is a Fourier transform spectrometer which works at fixed optical
path difference. It produces Doppler shift maps of the observed object.
Velocity amplitude of Jupiter's oscillations is expected below 60 cm/s. Results
Despite light technical defects, the instrument demonstrated to work correctly,
being limited only by photon noise, after a careful analysis. A noise level of
about 12 cm/s has been reached on a 10-night observation run, with 21 % duty
cycle, which is 5 time better than previous similar observations. However, no
signal from Jupiter is clearly highlighted.


title:
Measurement of two-halo neutron transfer reaction p($^{11}$Li,$^{9}$Li)t
  at 3$A$ MeV

abstract:
  The p(\nuc{11}{Li},\nuc{9}{Li})t reaction has been studied for the first time
at an incident energy of 3$A$ MeV delivered by the new ISAC-2 facility at
TRIUMF. An active target detector MAYA, build at GANIL, was used for the
measurement. The differential cross sectionshave been determined for
transitions to the \nuc{9}{Li} ground andthe first excited states in a wide
range of scattering angles. Multistep transfer calculations using different
\nuc{11}{Li} model wave functions, shows that wave functions with strong
correlations between the halo neutrons are the most successful in reproducing
the observation.


title:
Geometry of all supersymmetric four-dimensional ${\cal N}=1$
  supergravity backgrounds

abstract:
  We solve the Killing spinor equations of ${\cal N}=1$ supergravity, with four
supercharges, coupled to any number of vector and scalar multiplets in all
cases. We find that backgrounds with N=1 supersymmetry admit a null,
integrable, Killing vector field. There are two classes of N=2 backgrounds. The
spacetime in the first class admits a parallel null vector field and so it is a
pp-wave. The spacetime of the other class admits three Killing vector fields,
and a vector field that commutes with the three Killing directions. These
backgrounds are of cohomogeneity one with homogenous sections either
$\bR^{2,1}$ or $AdS_3$ and have an interpretation as domain walls. The N=3
backgrounds are locally maximally supersymmetric. There are N=3 backgrounds
which arise as discrete identifications of maximally supersymmetric ones. The
maximally supersymmetric backgrounds are locally isometric to either
$\bR^{3,1}$ or $AdS_4$.