title:
Hydrostatic pressure study of pure and doped La1-xRxAgSb2 (R = Ce, Nd)
  charge-density-wave compounds

abstract:
  The intermetallic compound LaAgSb2 displays two charge-density-wave (CDW)
transitions, which were detected with measurements of electrical resistivity
(rho), magnetic susceptibility, and X-ray scattering; the upper transition
takes place at T1 approx. 210 K, and it is accompanied by a large anomaly in
rho(T), whereas the lower transition is marked by a much more subtle anomaly at
T2 approx. 185 K. We studied the effect of hydrostatic pressure (P) on the
formation of the upper CDW state in pure and doped La1-xRxAgSb2 (R = Ce, Nd)
compounds, by means of measurements of rho(T) for P < 23 kbar. We found that
the hydrostatic pressure, as well as the chemical pressure introduced by the
partial substitution of the smaller Ce and Nd ions for La, result in the
suppression of the CDW ground state, e.g. the reduction of the ordering
temperature T1. The values of dT1/dP are approx. 2-4 times higher for the
Ce-doped samples as compared to pure LaAgSb2, or even La0.75Nd0.25AgSb2
Nd-doped with a comparable T1 (P=0). This increased sensitivity to pressure may
be due to increasing Ce- hybridization under pressure. The magnetic ordering
temperature of the cerium-doped compounds is also reduced by pressure, and the
high pressure behavior of the Ce-doped samples is dominated by Kondo impurity
scattering.


title: Attosecond Control of Ionization Dynamics

abstract:
  Attosecond pulses can be used to initiate and control electron dynamics on a
sub-femtosecond time scale. The first step in this process occurs when an atom
absorbs an ultraviolet photon leading to the formation of an attosecond
electron wave packet (EWP). Until now, attosecond pulses have been used to
create free EWPs in the continuum, where they quickly disperse. In this paper
we use a train of attosecond pulses, synchronized to an infrared (IR) laser
field, to create a series of EWPs that are below the ionization threshold in
helium. We show that the ionization probability then becomes a function of the
delay between the IR and attosecond fields. Calculations that reproduce the
experimental results demonstrate that this ionization control results from
interference between transiently bound EWPs created by different pulses in the
train. In this way, we are able to observe, for the first time, wave packet
interference in a strongly driven atomic system.


title:
Differential geometry of curves in Lagrange Grassmannians with given
  Young diagram

abstract:
  Curves in Lagrange Grassmannians appear naturally in the intrinsic study of
geometric structures on manifolds. By a smooth geometric structure on a
manifold we mean any submanifold of its tangent bundle, transversal to the
fibers. One can consider the time-optimal problem naturally associate with a
geometric structure. The Pontryagin extremals of this optimal problem are
integral curves of certain Hamiltonian system in the cotangent bundle. The
dynamics of the fibers of the cotangent bundle w.r.t. this system along an
extremal is described by certain curve in a Lagrange Grassmannian, called
Jacobi curve of the extremal. Any symplectic invariant of the Jacobi curves
produces the invariant of the original geometric structure. The basic
characteristic of a curve in a Lagrange Grassmannian is its Young diagram. The
number of boxes in its kth column is equal to the rank of the kth derivative of
the curve (which is an appropriately defined linear mapping) at a generic
point. We will describe the construction of the complete system of symplectic
invariants for parameterized curves in a Lagrange Grassmannian with given Young
diagram. It allows to develop in a unified way local differential geometry of
very wide classes of geometric structures on manifolds, including both
classical geometric structures such as Riemannian and Finslerian structures and
less classical ones such as sub-Riemannian and sub-Finslerian structures,
defined on nonholonomic distributions.


title:
Determination of localized conduction band-tail states distribution in
  single phase undoped microcrystalline silicon

abstract:
  We report on the phototransport properties of microstructurally well
characterized plasma deposited highly crystallized microcrystalline silicon
films. The steady state photoconductivity was measured on a wide
microstructural variety of single-phase undoped microcrystalline silicon films
as a function of temperature and light intensity. The band-tail parameter (kTc)
was calculated from the photoconductivity light intensity exponent values at
different temperatures for a range of quasi-Fermi energies. The localized tail
states distribution in the vicinity of conduction band edge of microcrystalline
silicon was estimated using the values of kTc. Our study shows that
microcrystalline silicon films possessing dissimilar microstructural attributes
exhibit different phototransport behaviors, which are linked to different
features of the density of states maps of the material.


title:
Spectral geometry, homogeneous spaces, and differential forms with
  finite Fourier series

abstract:
  Let G be a compact Lie group acting transitively on Riemannian manifolds M
and N. Let p be a G equivariant Riemannian submersion from M to N. We show that
a smooth differential form on N has finite Fourier series if and only if the
pull back has finite Fourier series on M


title:
Normal and anti Meyer-Neldel rule in conductivity of highly crystallized
  undoped microcrystalline silicon films

abstract:
  We have studied the electrical conductivity behavior of highly crystallized
undoped hydrogenated microcrystalline silicon films having different
microstructures. The dark conductivity is seen to follow Meyer Neldel rule
(MNR) in some films and anti MNR in others, which has been explained on the
basis of variation in the film microstructure and the corresponding changes in
the effective density of states distributions. A band tail transport and
statistical shift of Fermi level are used to explain the origin of MNR as well
as anti-MNR in our samples. The observation of MNR and anti MNR in electrical
transport behavior of microcrystalline silicon is discussed in terms of the
basic underlying physics of their origin and the significance of these
relationships.


title:
Fractional composition of large crystallite grains: a unique
  microstructural parameter to explain conduction behavior in single phase
  undoped microcrystalline silicon

abstract:
  We have studied the dark conductivity of a broad microstructural range of
plasma deposited single phase undoped microcrystalline silicon films in a wide
temperature range (15 - 450K) to identify the possible transport mechanisms and
the interrelationship between film microstructure and electrical transport
behavior. Different conduction behaviors seen in films with different
microstructures are explained in the context of underlying transport mechanisms
and microstructural features, for above and below room temperature
measurements. Our microstructural studies have shown that different ranges of
the percentage volume fraction of the constituent large crystallite grains
(Fcl) of the microcrystalline silicon films correspond to characteristically
different and specific microstructures, irrespective of deposition conditions
and thicknesses. Our electrical transport studies demonstrate that each type of
microcrystalline silicon material having a different range of Fcl shows
different electrical transport behaviors.


title: Search for \bar{B}^0\to\Lambda_c^+\bar{\Lambda}_c^- decay at Belle

abstract:
  We search for the doubly charmed baryonic decay
$\bar{B}^0\to\Lambda_c^+\bar{\Lambda}_c^-$, in a data sample of $520\times10^6$
$B{\bar B}$ events accumulated at the $\Upsilon(4S)$ resonance with the Belle
detector at the KEKB asymmetric e^+e^- collider. We find no significant signal
and set an upper limit of ${\cal
B}(\bar{B}^0\to\Lambda_c^+\bar{\Lambda}_c^-)<6.2\times10^{-5}$ at 90%
confidence level. The result is significantly below a naive extrapolation from
${\cal B}(B^-\to\Xi_c^0\bar{\Lambda}_c^)$ assuming a simple Cabibbo-suppression
factor of $|V_{cd}/V_{cs}|^2$. The small branching fraction could be attributed
to a suppression due to the large momentum of the baryonic decay products,
which has been observed in other charmed baryonic two-body B decays. trend
observed in other charmed baryonic two-body B decays.


title: Additivity of Spin^c Quantization under Cutting

abstract:
  A G-equivariant spin^c structure on a manifold gives rise to a virtual
representation of the group G, called the spin^c quantization of the manifold.
We present a cutting construction for S^1-equivariant spin^c manifolds, and
show that the quantization of the original manifold is isomorphic to the direct
sum of the quantizations of the cut spaces. Our proof uses Kostant-type
formulas, which express the quantization in terms of local data around the
fixed point set of the S^1-action.


title: Functional analysis via extensions of the band depth

abstract:
  The notion of data depth has long been in use to obtain robust location and
scale estimates in a multivariate setting. The depth of an observation is a
measure of its centrality, with respect to a data set or a distribution. The
data depths of a set of multivariate observations translates to a
center-outward ordering of the data. Thus, data depth provides a generalization
of the median to a multivariate setting (the deepest observation), and can also
be used to screen for extreme observations or outliers (the observations with
low data depth). Data depth has been used in the development of a wide range of
robust and non-parametric methods for multivariate data, such as non-parametric
tests of location and scale [Li and Liu (2004)], multivariate rank-tests [Liu
and Singh (1993)], non-parametric classification and clustering [Jornsten
(2004)], and robust regression [Rousseeuw and Hubert (1999)]. Many different
notions of data depth have been developed for multivariate data. In contrast,
data depth measures for functional data have only recently been proposed
[Fraiman and Muniz (1999), L\'{o}pez-Pintado and Romo (2006a)]. While the
definitions of both of these data depth measures are motivated by the
functional aspect of the data, the measures themselves are in fact invariant
with respect to permutations of the domain (i.e. the compact interval on which
the functions are defined). Thus, these measures are equally applicable to
multivariate data where there is no explicit ordering of the data dimensions.
In this paper we explore some extensions of functional data depths, so as to
take the ordering of the data dimensions into account.


title:
Linear Depenedences of Van Der Waals, Covalent and Valence Shell Radii
  of Atoms of Groups 1a - 8a on their Bohr Radii

abstract:
  An earlier finding that the van der waals radii are related to their de
broglie wavelengths for some non-metallic elements has been extended here to
show that in fact, they vary linearly with the ground state bohr radii for all
the elements of groups 1a to 8 a. Similarly, the valence shell radii and the
covalent radii are shown to be linearly dependent on the bohr radii. One table
of data and 5 figures have been provided here showing that all the above radii
are sums of two lengths, one of which is a multiple of the bohr radius and the
other, a positive or negative constant for each group of elements.


title: The hook fusion procedure and its generalisations

abstract:
  The fusion procedure provides a way to construct new solutions to the
Yang-Baxter equation. In the case of the symmetric group the fusion procedure
has been used to construct diagonal matrix elements using a decomposition of
the Young diagram into its rows or columns. We present a new construction which
decomposes the diagram into hooks, the great advantage of this is that it
minimises the number of auxiliary parameters needed in the procedure. We go on
to use the hook fusion procedure to find diagonal matrix elements
computationally and calculate supporting evidence to a previous conjecture.
  We are motivated by the construction of certain elements that allow us to
generate representations of the symmetric group and single out particular
irreducible components. In this way we may construct higher representations of
the symmetric group from elementary ones. We go some way to generalising the
hook fusion procedure by considering other decompositions of Young diagrams,
specifically into ribbons. Finally, we adapt our construction to the quantum
deformation of the symmetric group algebra known as the Hecke algebra.


title: Discovery of coherent millisecond X-ray pulsations in Aql X-1

abstract:
  We report the discovery of an episode of coherent millisecond X-ray pulsation
in the neutron star low-mass X-ray binary Aql X-1. The episode lasts for
slightly more than 150 seconds, during which the pulse frequency is consistent
with being constant. No X-ray burst or other evidence of thermonuclear burning
activity is seen in correspondence with the pulsation, which can thus be
identified as occurring in the persistent emission. The pulsation frequency is
550.27 Hz, very close (0.5 Hz higher) to the maximum reported frequency from
burst oscillations in this source. Hence we identify this frequency with the
neutron star spin frequency. The pulsed fraction is strongly energy dependent,
ranging from <1% (3-5 keV) to >10% (16-30 keV). We discuss possible physical
interpretations and their consequences for our understanding of the lack of
pulsation in most neutron star low-mass X-ray binaries. If interpreted as
accretion-powered pulsation, Aql X-1 might play a key role in understanding the
differences between pulsating and non-pulsating sources.


title: Probing for the Cosmological Parameters with PLANCK Measurement

abstract:
  We investigate the constraints on cosmological parameters especially for EoS
of dark energy, inflationary parameters, neutrino mass and curvature of
universe using simulated Planck data. Firstly we determine cosmological
parameters with current observations including ESSENCE, WMAP3, Boomerang-2K2,
CBI, VSA, ACBAR, SDSS LRG and 2dFGRS, and take best-fit model as the fiducial
model in simulations. In simulations we pay attention to the effects of
dynamical dark energy in determination of cosmological parameters. We add
simulated SNAP data to do all the simulations. Using present data, we find
Quintom dark energy model is mildly favored while \LambdaCDM remains a good
fit. In the framework of dynamical dark energy, the constraints on inflationary
parameters, m_{\nu} and \Omega_{K} become weak compared with the constraints in
\LambdaCDM. Intriguingly, we find that the inflationary models with a "blue"
tilt, which are excluded about 2\sigma in \LambdaCDM model, are well within
2\sigma region with the presence of the dynamics of dark energy. The upper
limits of neutrino mass are weakened by a factor of 2 (95% C.L.), say,
m_{\nu}<1.59 eV and m_{\nu}<1.53 eV for two forms of parametrization of the
equation of state of dark energy. The flat universe is a good fit to the
current data, namely, |\Omega_{K}|<0.03 (95% C.L.). With the simulated Planck
and SNAP data, dynamical dark energy and \LambdaCDM might be distinguished at
4\sigma. And uncertainties of inflationary parameters, m_{\nu} and \Omega_{K}
can be reduced obviously. We also constrain the rotation angle \Delta\alpha,
denoting possible cosmological CPT violation, with simulated Planck and CMBpol
data and find that our results are much more stringent than current constraint
and will verify cosmological CPT symmetry with a higher precision. (Abridged)


title:
Weyl functions, inverse problem and special solutions for the system
  auxiliary to the nonlinear optics equation

abstract:
  A Borg-Marchenko type uniqueness theorem (in terms of the Weyl function) is
obtained here for the system auxiliary to the N-wave equation. A procedure to
solve inverse problem is used for this purpose. The asymptotic condition on the
Weyl function, under which the inverse problem is uniquely solvable, is
completed by the new and simple sufficient condition on the potential, granting
the fulfillment of this asymptotic condition. The evolution of the Weyl
function is discussed and the solution of an initial-boundary value problem for
the N-wave equation follows. Explicit solutions of the system are obtained.
System with a shifted argument is treated.


title:
Distribution of periodic torus orbits and Duke's theorem for cubic
  fields

abstract:
  We study periodic torus orbits on spaces of lattices. Using the action of the
group of adelic points of the underlying tori, we define a natural equivalence
relation on these orbits, and show that the equivalence classes become
uniformly distributed. This is a cubic analogue of Duke's theorem about the
distribution of closed geodesics on the modular surface: suitably interpreted,
the ideal classes of a cubic totally real field are equidistributed in the
modular 5-fold SL_3(Z)\SL_3(R)/SO_3(R). In particular, this proves (a stronger
form of) the folklore conjecture that the collection of maximal compact flats
in SL_3(Z)\SL_3(R)/SO_3(R) of volume less than V becomes equidistributed as V
goes to infinity. The proof combines subconvexity estimates, measure
classification, and local harmonic analysis.


title: Integrability of a conducting elastic rod in a magnetic field

abstract:
  We consider the equilibrium equations for a conducting elastic rod placed in
a uniform magnetic field, motivated by the problem of electrodynamic space
tethers. When expressed in body coordinates the equations are found to sit in a
hierarchy of non-canonical Hamiltonian systems involving an increasing number
of vector fields. These systems, which include the classical Euler and
Kirchhoff rods, are shown to be completely integrable in the case of a
transversely isotropic rod; they are in fact generated by a Lax pair. For the
magnetic rod this gives a physical interpretation to a previously proposed
abstract nine-dimensional integrable system. We use the conserved quantities to
reduce the equations to a four-dimensional canonical Hamiltonian system,
allowing the geometry of the phase space to be investigated through Poincar\'e
sections. In the special case where the force in the rod is aligned with the
magnetic field the system turns out to be superintegrable, meaning that the
phase space breaks down completely into periodic orbits, corresponding to
straight twisted rods.


title:
Remark on fundamental groups and effective Diophantine methods for
  hyperbolic curves

abstract:
  We discuss how non-commutative fundamental groups could eventually contribute
to algorithms for finding rational points on hyperbolic curves.


title:
A variant of the Recoil Growth algorithm to generate multi-polymer
  systems

abstract:
  The Recoil Growth algorithm, proposed in 1999 by Consta et al., is one of the
most efficient algorithm available in the literature to sample from a
multi-polymer system. Such problems are closely related to the generation of
self-avoiding paths. In this paper, we study a variant of the original Recoil
Growth algorithm, where we constrain the generation of a new polymer to take
place on a specific class of graphs. This makes it possible to make a fine
trade-off between computational cost and success rate. We moreover give a
simple proof for a lower bound on the irreducibility of this new algorithm,
which applies to the original algorithm as well.


title:
The cosine law at the atomic scale: Toward realistic simulations of
  Knudsen diffusion

abstract:
  We propose to revisit the diffusion of atoms in the Knudsen regime in terms
of a complex dynamical reflection process. By means of molecular dynamics
simulation we emphasize the asymptotic nature of the cosine law of reflection
at the atomic scale, and carefully analyze the resulting strong correlations in
the reflection events. A dynamical interpretation of the accomodation
coefficient associated to the slip at the wall interface is also proposed.
Finally, we show that the first two moments of the stochastic process of
reflection non uniformly depend on the incident angle.


title: Flavour symmetry breaking and meson masses

abstract:
  The axial-vector Ward-Takahashi identity is used to derive mass formulae for
neutral pseudoscalar mesons. Flavour symmetry breaking entails non-ideal
flavour content for these states. Adding that the \eta^\prime is not a
Goldstone mode, exact chiral-limit relations are developed from the identity.
They connect the dressed-quark propagator to the topological susceptibility. It
is confirmed that in the chiral limit the \eta^\prime mass is proportional to
the matrix element which connects this state to the vacuum via the topological
susceptibility. The implications of the mass formulae are illustrated using an
elementary dynamical model, which includes an Ansatz for that part of the
Bethe-Salpeter kernel related to the non-Abelian anomaly. In addition to the
current-quark masses, the model involves two parameters, one of which is a
mass-scale. It is employed in an analysis of pseudoscalar- and vector-meson
bound-states. While the effects of SU(N_f=2) and SU(N_f=3) flavour symmetry
breaking are emphasised, the five-flavour spectra are described. Despite its
simplicity, the model is elucidative and phenomenologically efficacious; e.g.,
it predicts \eta-\eta^\prime mixing angles of ~ (-15 degrees) and \pi^0-\eta
angles of ~ 1 degree.


title:
Spiral Disk Opacity from Occulting Galaxy Pairs in the Sloan Digital Sky
  Survey

abstract:
  A spiral galaxy partially ovelapping a more distant elliptical offers an
unique opportunity to measure the dust extinction in the foreground spiral.
  From the Sloan Digital Sky Survey DR4 spectroscopic sample, we selected 83
occulting galaxy pairs and measured disk opacity over the redshift range z =
0.0-0.2 with the goal to determine the recent evolution of disk dust opacity.
The enrichment of the ISM changes over the lifetime of a disk and it is
reasonable to expect the dust extinction properties of spiral disks as a whole
to change over their lifetime. When they do, the change will affect our
measurements of galaxies over the observable universe.
  From the SDSS pairs we conclude that spiral disks show evidence of extinction
to ~2 effective radii. However, no evidence for recent evolution of disk
opacity is evident, due to the limited redshift range and our inability to
distinguish other factors on disk opacity such as the presence of spiral arms
and Hubble type. Such effects also mask any relation between surface brightness
and optical depth that has been found in nearby galaxies. Hence, we conclude
that the SDSS spectral catalog is an excellent way to find occulting pairs and
construct a uniform local sample. However, higher resolution than the SDSS
images is needed to disentangle the effects of spiral arms and Hubble type from
evolution since z = 0.2.


title: Molecular gas in high-velocity clouds: revisited scenario

abstract:
  We report a new search for 12CO(1-0) emission in high-velocity clouds (HVCs)
performed with the IRAM 30 m telescope. This search was motivated by the recent
detection of cold dust emission in the HVCs of Complex C. Despite a spatial
resolution which is three times better and sensitivity twice as good compared
to previous studies, no CO emission is detected in the HVCs of Complex C down
to a best 5 sigma limit of 0.16 K km/s at a 22'' resolution. The CO emission
non-detection does not provide any evidence in favor of large amounts of
molecular gas in these HVCs and hence in favor of the infrared findings. We
discuss different configurations which, however, allow us to reconcile the
negative CO result with the presence of molecular gas and cold dust emission.
H2 column densities higher than our detection limit, N(H2) = 3x10^{19} cm^{-2},
are expected to be confined in very small and dense clumps with 20 times
smaller sizes than the 0.5 pc clumps resolved in our observations according to
the results obtained in cirrus clouds, and might thus still be highly diluted.
As a consequence, the inter-clump gas at the 1 pc scale has a volume density
lower than 20 cm^{-3} and already appears as too diffuse to excite the CO
molecules. The observed physical conditions in the HVCs of Complex C also play
an important role against CO emission detection. It has been shown that the
CO-to-H2 conversion factor in low metallicity media is 60 times higher than at
the solar metallicity, leading for a given H2 column density to a 60 times
weaker integrated CO intensity. And the very low dust temperature estimated in
these HVCs implies the possible presence of gas cold enough (< 20 K) to cause
CO condensation onto dust grains under interstellar medium pressure conditions
and thus CO depletion in gas-phase observations.


title: Next-to-leading order corrections in exclusive meson production

abstract:
  We analyze in detail the size of next-to-leading order corrections to hard
exclusive meson production within the collinear factorization approach.
Corrections to the cross section are found to be huge at small xB and
substantial in typical fixed-target kinematics. With the models we take for
nucleon helicity-flip distributions, the transverse target polarization
asymmetry in vector meson production is strongly affected by radiative
corrections, except at large xB. Its overall size is very small for rho
production but can be large in the omega channel.


title:
Bose-Einstein study of position-momentum correlations of charged pions
  in hadronic Z0 decays

abstract:
  A study of Bose-Einstein correlations in pairs of identically charged pions
produced in e+e- annihilations at the Z0 peak has been performed for the first
time assuming a non-static emitting source. The results are based on the high
statistics data obtained with the OPAL detector at LEP. The correlation
functions have been analyzed in intervals of the average pair transverse
momentum and of the pair rapidity, in order to study possible correlations
between the pion production points and their momenta (position-momentum
correlations). The Yano-Koonin and the Bertsch-Pratt parameterizations have
been fitted to the measured correlation functions to estimate the geometrical
parameters of the source as well as the velocity of the source elements with
respect to the overall centre-of-mass frame. The source rapidity is found to
scale approximately with the pair rapidity, and both the longitudinal and
transverse source dimensions are found to decrease for increasing average pair
transverse momenta.


title:
Dynamical glass transition: critical temperature T_c and memory kernel
  in MD-simulated Ni_{0.8}Zr_{0.2}

abstract:
  We use molecular dynamics computer simulations to investigate a critical
temperature T_c for a dynamical glass transition as proposed by the
mode-coupling theory (MCT) of dense liquids in a glass forming
Ni_{0.8}Zr_{0.2}-system. The critical temperature T_c are analyzed from
different quantities and checked the consistency of the estimated values, i.e.
from (i) the non-vanishing nonergodicity parameters as asymptotic solutions of
the MCT equations in the arrested state, (ii) the ${\bf{g}}_m$-parameters
describing the approach of the melt towards the arrested state on the ergodic
side, (iii) the diffusion coefficients in the melt. The resulting T_c values
are found to agree within about 10%.


title: Warp diffusion in accretion discs: a numerical investigation

abstract:
  In this paper we explore numerically the evolution of a warped accretion
disc. Here, we focus here on the regime where the warp evolves diffusively. By
comparing the numerical results to a simple diffusion model, we are able to
determine the diffusion coefficient of the warp, $\alpha_2$, as a function of
the relevant disc parameters. We find that while in general the disc behaviour
is well reproduced by the diffusion model and for relatively large viscosities
the warp diffusion is well described by the linear theory (in particular
confirming that the warp diffusion coefficient is inversely proportional to
viscosity), significant non-linear effects are present as the viscosity becomes
smaller, but still dominates over wave-propagation effects. In particular, we
find that the inverse dependence of the diffusion coefficient on viscosity
breaks down at low viscosities, so that $\alpha_2$ never becomes larger than a
saturation value $\alpha_{\rm max}$ of order unity. This can have major
consequences in the evolution of systems where a warped disc is present. In
particular, it affects the location of the warp radius in the Bardeen-Petterson
effect and therefore the spin up (or spin down) of supermassive black holes in
the nuclei of galaxies. Additionally, we also find that while the rate of warp
diffusion does not depend significantly on the detailed viscosity formulation,
the rate of internal precession generated by the warp is strongly affected by
it. Such effects should be considered with care when modeling the evolution of
warped discs. This emphasises the need to test the above results using
different numerical schemes, and with higher resolution, in order to
investigate the degree to which numerical simulations are able to provide
accurate modeling of the complex fluid dynamics of warped discs. (Abridged)


title: N=2 supersymmetric unconstrained matrix GNLS hierarchies are consistent

abstract:
  We develop a pseudo-differential approach to the N=2 supersymmetric
unconstrained matrix (k|n,m)-Generalized Nonlinear Schroedinger hierarchies and
prove consistency of the corresponding Lax-pair representation
(nlin.SI/0201026). Furthermore, we establish their equivalence to the
integrable hierarchies derived in the super-algebraic approach of the
homogeneously-graded loop superalgebra sl(2k+n|2k+m)\otimes
C[{lambda},{lambda}^{-1}] (nlin.SI/0206037). We introduce an unconventional
definition of N=2 supersymmetric strictly pseudo-differential operators so as
to close their algebra among themselves.


title:
Janus particles with coupled electric and magnetic moments make a
  disordered magneto-electric medium

abstract:
  We demonstrate that by combining permanent electric and magnetic moments in
particles, it is possible to realize a new type of medium that allows for a
cross-correlation between electric and magnetic properties of matter, known as
magnetoelectric coupling. Magnetoelectric materials have so far been restricted
to systems that exhibit long-range order in their electric and magnetic
moments. Here, we show that a room-temperature, switchable magnetoelectric can
be realized that is naturally disordered. The building blocks are Tellegen
particles that orient in either an electric or a magnetic field.


title:
Coincidence measurement of residues and light particles in the reaction
  56Fe+p at 1 GeV per nucleon with SPALADIN

abstract:
  The spallation of $^{56}$Fe in collisions with hydrogen at 1 A GeV has been
studied in inverse kinematics with the large-aperture setup SPALADIN at GSI.
Coincidences of residues with low-center-of-mass kinetic energy light particles
and fragments have been measured allowing the decomposition of the total
reaction cross-section into the different possible de-excitation channels.
Detailed information on the evolution of these de-excitation channels with
excitation energy has also been obtained. The comparison of the data with
predictions of several de-excitation models coupled to the INCL4 intra-nuclear
cascade model shows that only GEMINI can reasonably account for the bulk of
collected results, indicating that in a light system with no compression and
little angular momentum, multifragmentation might not be necessary to explain
the data.


title:
Calculations of the Exciton Coupling Elements Between the DNA Bases
  Using the Transition Density Cube Method

abstract:
  Excited states of the of the double-stranded DNA model
(A)$_{12}\cdot$(T)_{12} were calculated in the framework of the exciton theory.
The off-diagonal elements of the exciton matrix were calculated using the
transition densities and ideal dipole approximation associated with the lowest
energy $\pi\pi^{*}$ excitations of the individual nucleobases obtained from
TDDFT calculations. The values of the coupling calculated with the transition
density cubes (TDC) and ideal-dipole approximation (IDA) methods were found
significantly different for the small inter-chromophore distances. It was shown
that the IDA overestimates the coupling significantly. The effects of the
structural fluctuations were incorporated by averaging the properties of the
excited states over a large number of conformations obtained from the MD
simulations.


title: Experimental realization of a quantum game on a one-way quantum computer

abstract:
  We report the first demonstration of a quantum game on an all-optical one-way
quantum computer. Following a recent theoretical proposal we implement a
quantum version of Prisoner's Dilemma, where the quantum circuit is realized by
a 4-qubit box-cluster configuration and the player's local strategies by
measurements performed on the physical qubits of the cluster. This
demonstration underlines the strength and versatility of the one-way model and
we expect that this will trigger further interest in designing quantum
protocols and algorithms to be tested in state-of-the-art cluster resources.


title: Complex Datasets and Inverse Problems. Tomography, Networks and Beyond

abstract:
  This book is a collection of papers dedicated to the memory of Yehuda Vardi.
Yehuda was the chair of the Department of Statistics of Rutgers University when
he passed away unexpectedly on January 13, 2005. On October 21--22, 2005, some
150 leading scholars from many different fields, including statistics,
telecommunications, biomedical engineering, bioinformatics, biostatistics and
epidemiology, gathered at Rutgers in a conference in his honor. This conference
was on ``Complex Datasets and Inverse Problems: Tomography, Networks, and
Beyond,'' and was organized by the editors. The present collection includes
research work presented at the conference, as well as contributions from
Yehuda's colleagues. The theme of the conference was networks and other
important and emerging areas of research involving incomplete data and
statistical inverse problems. Networks are abundant around us: communication,
computer, traffic, social and energy are just a few examples. As enormous
amounts of network data are collected in this information age, the field has
attracted a great amount of attention from researchers in statistics and
computer engineering as well as telecommunication providers and various
government agencies. However, few statistical tools have been developed for
analyzing network data as they are typically governed by time-varying and
mutually dependent communication protocols sitting on complicated
graph-structured network topologies. Many prototypical applications in these
and other important technologies can be viewed as statistical inverse problems
with complex, massive, high-dimensional and possibly biased/incomplete data.
This unifying theme of inverse problems is particularly appropriate for a
conference and volume dedicated to the memory of Yehuda. Indeed he made
influential contributions to these fields, especially in medical tomography,
biased data, statistical inverse problems, and network tomography.


title:
Global attraction to solitary waves for Klein-Gordon equation with mean
  field interaction

abstract:
  We consider a U(1)-invariant nonlinear Klein-Gordon equation in dimension one
or larger, self-interacting via the mean field mechanism. We analyze the
long-time asymptotics of finite energy solutions and prove that, under certain
generic assumptions, each solution converges (as time goes to infinity) to the
two-dimensional set of all ``nonlinear eigenfunctions'' of the form
$\phi(x)e\sp{-i\omega t}$. This global attraction is caused by the nonlinear
energy transfer from lower harmonics to the continuous spectrum and subsequent
dispersive radiation.


title: Peculiar acceleration

abstract:
  It has been proposed recently to observe the change in cosmological redshift
of distant galaxies or quasars with the next generation of large telescope and
ultra-stable spectrographs (the so-called Sandage-Loeb test). Here we
investigate the possibility of observing the change in peculiar velocity in
nearby clusters and galaxies. This ``peculiar acceleration'' could help
reconstructing the gravitational potential without assuming virialization. We
show that the expected effect is of the same order of magnitude of the
cosmological velocity shift. Finally, we discuss how to convert the theoretical
predictions into quantities directly related to observations.


title: The quasiparticle spectral function in doped graphene

abstract:
  We calculate the real and imaginary electron self-energy as well as the
quasiparticle spectral function in doped graphene taking into account
electron-electron interaction in the leading order dynamically screened Coulomb
coupling. Our theory provides the basis for calculating {\it all} one-electron
properties of extrinsic graphene. Comparison with existing ARPES measurements
shows broad qualitative agreement between theory and experiment. We also
calculate the renormalized graphene momentum distribution function, finding a
typical Fermi liquid discontinuity at k_F. We also provide a critical
discussion of the relevant many body approximations (e.g. RPA) for graphene.


title:
Quantum transport in semiconductor quantum dot superlattices:
  electron-phonon resonances and polaron effects

abstract:
  Electron transport in periodic quantum dot arrays in the presence of
interactions with phonons was investigated using the formalism of
nonequilibrium Green's functions. The self-consistent Born approximation was
used to model the self-energies. Its validity was checked by comparison with
the results obtained by direct diagonalization of the Hamiltonian of
interacting electrons and longitudinal optical phonons. The nature of charge
transport at electron -- phonon resonances was investigated in detail and
contributions from scattering and coherent tunnelling to the current were
identified. It was found that at larger values of the structure period the main
peak in the current -- field characteristics exhibits a doublet structure which
was shown to be a transport signature of polaron effects. At smaller values of
the period, electron -- phonon resonances cause multiple peaks in the
characteristics. A phenomenological model for treatment of nonuniformities of a
realistic quantum dot ensemble was also introduced to estimate the influence of
nonuniformities on current -- field characteristics.


title: Charge transport in arrays of PbSe nanocrystals

abstract:
  We report electrical transport measurements of arrays of PbSe nanocrystals
forming the channels of field effect transistors. We measure the current in
these devices as a function of source-drain voltage, gate voltage and
temperature. Annealing is necessary to observe measurable current after which a
simple model of hopping between intrinsic localized states describes the
transport properties of the nanocrystal solid. We find that the majority
carriers are holes, which are thermally released from acceptor states. At low
source-drain voltages, the activation energy for the conductivity is given by
the energy required to generate holes plus the activation over barriers
resulting from site disorder. At high source-drain voltages the activation
energy is given by the former only. The thermal activation energy of the
zero-bias conductance indicates that the Fermi energy is close to the
highest-occupied valence level, the 1Sh state, and this is confirmed by
field-effect measurements, which give a density of states of approximately
eight per nanocrystal as expected from the degeneracy of the 1Sh state.


title: Spatial effects on the speed and reliability of protein-DNA search

abstract:
  Strong experimental and theoretical evidence shows that transcription factors
and other specific DNA-binding proteins find their sites using a two-mode
search: alternating between 3D diffusion through the cell and 1D sliding along
the DNA. We consider the role spatial effects in the mechanism on two different
scales. First, we reconcile recent experimental findings by showing that the 3D
diffusion of the transcription factor is often local, i.e. the transcription
factor lands quite near its dissociation site. Second, we discriminate between
two types of searches: global searches and local searches. We show that these
searches differ significantly in average search time and the variability of
search time. Using experimentally measured parameter values, we also show that
1D and 3D search is not optimally balanced, leading to much larger estimates of
search time. Together, these results lead to a number of biological
implications including suggestions of how prokaryotes and eukaryotes achieve
rapid gene regulation and the relationship between the search mechanism and
noise in gene expression.


title: Quantum Walks on a Random Environment

abstract:
  Quantum walks are considered in a one-dimensional random medium characterized
by static or dynamic disorder. Quantum interference for static disorder can
lead to Anderson localization which completely hinders the quantum walk and it
is contrasted with the decoherence effect of dynamic disorder having strength
W, where a quantum to classical crossover at time $t_{c}\propto W^{-2}$
transforms the quantum walk into an ordinary random walk with diffusive
spreading. We demonstrate these localization and decoherence phenomena in
quantum carpets of the observed time evolution and examine in detail a dimer
lattice which corresponds to a single qubit subject to randomness.


title: Progressive star formation in the young SMC cluster NGC 602

abstract:
  NGC 602 is a young stellar cluster located in a peripheral region of the
Small Magellanic Cloud known as the wing. Far from the main body of the galaxy
and abutting the Magellanic Bridge, the SMC's wing is characterized by low gas
and stellar content. With deep optical imaging from the Advanced Camera for
Surveys (ACS) aboard the Hubble Space Telescope (HST), we have discovered an
extensive pre-Main Sequence (PMS) population, with stellar masses in the range
0.6-3 Solar masses. These low mass PMS stars formed coevally with the central
cluster about 4 Myr ago. Spitzer Space Telescope (Spitzer) images of the same
region from the Infrared Array Camera (IRAC) also reveal a population of Young
Stellar Objects (YSOs), some of which are still embedded in nebular material
and most of which likely formed even more recently than the young stars
detected with HST/ACS imaging. We infer that star formation started in this
region about 4 Myr ago with the formation of the central cluster and gradually
propagated towards the outskirts where star formation is presently ongoing.


title: The Quantum Hydrodynamics of the Sutherland Model

abstract:
  We show that the form of the chiral condition found by Abanov et al., in the
quantum hydrodyamics of the Sutherland model arises because there are two
distinct inner products with respect to which the chiral Hamitonian hermitian,
but only one with respect to which the full, non-chiral, Hamiltonian is
hermitian.


title:
Liquid elasticity length, universal dynamic crossovers and glass
  transition

abstract:
  We discuss two main universal dynamic crossovers in a liquid that correspond
to relaxation times of 1 ps and 10^{-7}--10^{-6} s. We introduce the concept of
liquid elasticity length $d_{\rm el}$. At room temperature, $d_{\rm el}$ is
several \AA in water and increases to 0.01 mm in honey and 1 mm in tar. We
discuss that on temperature decrease, $d_{\rm el}=d_{\rm m}$ and $d_{\rm el}=L$
correspond to the two dynamic crossovers, where $d_{\rm m}$ is the medium-range
order and L is system size. The second crossover defines all kinetic aspects of
the glass transition whereas ``thermodynamic'' glass transition is realized in
the limit of infinite system size only. One prediction of this picture is the
increase of viscosity with the size of macroscopic system, which we verify by
measuring the viscosity of honey.


title: The periodic standing-wave approximation: post-Minkowski computation

abstract:
  The periodic standing wave method studies circular orbits of compact objects
coupled to helically symmetric standing wave gravitational fields. From this
solution an approximation is extracted for the strong field, slowly
inspiralling motion of black holes and binary stars. Previous work on this
model has dealt with nonlinear scalar models, and with linearized general
relativity. Here we present the results of the method for the post-Minkowski
(PM) approximation to general relativity, the first step beyond linearized
gravity. We compute the PM approximation in two ways: first, via the standard
approach of computing linearized gravitational fields and constructing from
them quadratic driving sources for second-order fields, and second, by solving
the second-order equations as an ``exact'' nonlinear system. The results of
these computations have two distinct applications: (i) The computational
infrastructure for the ``exact'' PM solution will be directly applicable to
full general relativity. (ii) The results will allow us to begin supplying
initial data to collaborators running general relativistic evolution codes.


title:
Extracting signatures of quantum criticality in the finite-temperature
  behavior of many-body systems

abstract:
  We face the problem of detecting and featuring footprints of quantum
criticality in the finite-temperature behavior of quantum many-body systems.
Our strategy is that of comparing the phase diagram of a system displaying a
T=0 quantum phase transition with that of its classical limit, in order to
single out the genuinely quantum effects. To this aim, we consider the
one-dimensional Ising model in a transverse field: while the quantum S=1/2
Ising chain is exactly solvable and extensively studied, results for the
classical limit (infinite S) of such model are lacking, and we supply them
here. They are obtained numerically, via the Transfer-matrix method, and their
asymptotic low-temperature behavior is also derived analytically by
self-consistent spin-wave theory. We draw the classical phase-diagram according
to the same procedure followed in the quantum analysis, and the two phase
diagrams are found unexpectedly similar: Three regimes are detected also in the
classical case, each characterized by a functional dependence of the
correlation length on temperature and field analogous to that of the quantum
model. What discriminates the classical from the quantum case are the different
values of the exponents entering such dependencies, a consequence of the
different nature of zero-temperature quantum fluctuations with respect to
thermal ones.


title:
The anomalous Hall Effect and magnetoresistance in the layered
  ferromagnet Fe_{1/4}TaS_2: the inelastic regime

abstract:
  The large magnetic anisotropy in the layered ferromagnet Fe_{1/4}TaS_2 leads
to very sharp reversals of the magnetization $\bf M$ at the coercive field. We
have exploited this feature to measure the anomalous Hall effect (AHE),
focussing on the AHE conductivity $\sigma^A_{xy}$ in the inelastic regime. At
low temperature T (5-50 K), $\sigma^A_{xy}$ is T-independent, consistent with
the Berry-phase/Karplus-Luttinger theory. Above 50 K, we extract an inelastic
AHE conductivity $\sigma^{in}_{xy}$ that scales as the square of $\Delta\rho$
(the T dependent part of the resistivity $\rho$). The term $\sigma^{in}_{xy}$
clarifies the T dependence and sign-reversal of the AHE coefficient R_s(T). We
discuss the possible ubiquity of $\sigma^{in}_{xy}$ in ferromagnets, and ideas
for interpreting its scaling with $(\Delta\rho)^2$. Measurements of the
magnetoresistance (MR) reveal a rich pattern of behavior vs. T and field
tilt-angle. We show that the 2 mechanisms, the anisotropic MR effect and
field-suppression of magnons, account for the intricate MR behavior, including
the bow-tie features caused by the sharp reversals in $\bf M$.


title:
Effects of Axion-Photon Mixing on Gamma-Ray Spectra from Magnetized
  Astrophysical Sources

abstract:
  Astrophysical gamma-ray sources come in a variety of sizes and
magnetizations. We deduce general conditions under which gamma-ray spectra from
such sources would be significantly affected by axion-photon mixing. We show
that, depending on strength and coherence of the magnetic field, axion
couplings down to ~ 1/(10**13 GeV) can give rise to significant axion-photon
conversions in the environment of accreting massive black holes. Resonances can
occur between the axion mass term and the plasma frequency term as well as
between the plasma frequency term and the vacuum Cotton-Mouton shift. Both
resonances and non-resonant transitions could induce detectable features or
even strong suppressions in finite energy intervals of gamma-ray spectra from
active galactic nuclei. Such effects can occur at keV to TeV energies for
couplings that are currently allowed by all experimental constraints.


title: The prevalence of FRI radio quasars

abstract:
  We present deep, multi-VLA-configuration radio images for a set of 18
quasars, having redshifts between 0.36 and 2.5, from the 7C quasar survey.
Approximately one quarter of these quasars have FRI-type twin-jet structures
and the remainder are a broad range of wide angle tail, fat double, classical
double, core-jet and hybrid sources. These images demonstrate that FRI quasars
are prevalent in the universe, rather than non-existent as had been suggested
in the literature prior to the serendipitous discovery of the first FRI quasar
a few years ago, the optically powerful "radio quiet" quasar E1821+643. Some of
the FRI quasars have radio luminosities exceeding the traditional FRI / FRII
break luminosity, however we find no evidence for FRII quasars with
luminosities significantly below the break. We consider whether the existence
of such high luminosity FRI structures is due to the increasingly inhomogeneous
environments in the higher redshift universe.


title:
Stochastic Knapsack Problem Revisited: Switch-Over Policies and Dynamic
  Pricing

abstract:
  The stochastic knapsack has been used as a model in wide ranging applications
from dynamic resource allocation to admission control in telecommunication. In
recent years, a variation of the model has become a basic tool in studying
problems that arise in revenue management and dynamic/flexible pricing; and it
is in this context that our study is undertaken. Based on a dynamic programming
formulation and associated properties of the value function, we study in this
paper a class of control that we call switch-over policies -- start from
accepting only orders of the highest price, and switch to including lower
prices as time goes by, with the switch-over times optimally decided via convex
programming. We establish the asymptotic optimality of the switch-over policy,
and develop pricing models based on this policy to optimize the price
reductions over the decision horizon.


title: Influence of polymer-pore interactions on translocation

abstract:
  We investigate the influence of polymer-pore interactions on the
translocation dynamics using Langevin dynamics simulations. An attractive
interaction can greatly improve translocation probability. At the same time, it
also increases translocation time slowly for weak attraction while exponential
dependence is observed for strong attraction. For fixed driving force and chain
length the histogram of translocation time has a transition from Gaussian
distribution to long-tailed distribution with increasing attraction. Under a
weak driving force and a strong attractive force, both the translocation time
and the residence time in the pore show a non-monotonic behavior as a function
of the chain length. Our simulations results are in good agreement with recent
experimental data.


title: Automorphisms and derivations of free Poisson algebras in two variables

abstract:
  Let P be a free Poisson algebra in two variables over a field of
characteristic zero. We prove that the automorphisms of P are tame and that the
locally nilpotent derivations of P are triangulable.


title:
Discovery of Pulsations and a Possible Spectral Feature in the X-ray
  Emission from Rotating Radio Transient J1819-1458

abstract:
  PSR J1819-1458 is a rotating radio transient (RRAT) source with an inferred
surface dipole magnetic field strength of 5e13 G and a 4.26-s spin period. We
present XMM-Newton observations of the X-ray counterpart of this source, CXOU
J181939.1-145804, in which we identify pulsations and a possible spectral
feature. The X-ray pulsations are at the period predicted by the radio
ephemeris, providing an unambiguous identification with the radio source and
confirmation of its neutron star nature. The X-ray pulse has a 0.3-5 keV pulsed
fraction of 34% and is aligned with the expected phase of the radio pulse. The
X-ray spectrum is fit well by an absorbed blackbody with kT = 0.14 keV with the
addition of an absorption feature at 1 keV, with total absorbed flux of 1.5e-13
ergs/cm^2/s (0.3-5 keV). This absorption feature is well modeled by a Gaussian
or resonant cyclotron scattering model, but its significance is dependent on
the choice of continuum model. We find no evidence for any X-ray bursts or
aperiodic variability on timescales of 6 ms to the duration of the observation
and can place the most stringent limit to date of < 3e-9 ergs/cm^2/s on the
absorbed 0.3-5 keV flux of any bursts.


title:
A Practical Ontology for the Large-Scale Modeling of Scholarly Artifacts
  and their Usage

abstract:
  The large-scale analysis of scholarly artifact usage is constrained primarily
by current practices in usage data archiving, privacy issues concerned with the
dissemination of usage data, and the lack of a practical ontology for modeling
the usage domain. As a remedy to the third constraint, this article presents a
scholarly ontology that was engineered to represent those classes for which
large-scale bibliographic and usage data exists, supports usage research, and
whose instantiation is scalable to the order of 50 million articles along with
their associated artifacts (e.g. authors and journals) and an accompanying 1
billion usage events. The real world instantiation of the presented abstract
ontology is a semantic network model of the scholarly community which lends the
scholarly process to statistical analysis and computational support. We present
the ontology, discuss its instantiation, and provide some example inference
rules for calculating various scholarly artifact metrics.


title: Noncommutativity and theta-locality

abstract:
  In this paper, we introduce the condition of theta-locality which can be used
as a substitute for microcausality in quantum field theory on noncommutative
spacetime. This condition is closely related to the asymptotic commutativity
which was previously used in nonlocal QFT. Heuristically, it means that the
commutator of observables behaves at large spacelike separation like
$\exp(-|x-y|^2/\theta)$, where $\theta$ is the noncommutativity parameter. The
rigorous formulation given in the paper implies averaging fields with suitable
test functions. We define a test function space which most closely corresponds
to the Moyal star product and prove that this space is a topological algebra
under the star product. As an example, we consider the simplest normal ordered
monomial $:\phi\star\phi:$ and show that it obeys the theta-locality condition.


title: Luminosity volume test for compact steep spectrum radio sources

abstract:
  We apply the V/Vm test to a subsample of compact steep-spectrum sources from
a complete sample of radio sources selected at 2.7 GHz. We find that the <V/Vm>
has a value intermediate between those found for samples of extended
steep-spectrum sources and those of compact flat-spectrum sources. If the
sample is split into two further classes of sources having more steep and less
steep spectra, the <V/Vm> values for these then tally roughly with those found
for the extended steep-spectrum and compact flat-spectrum classes of sources.
Implications of this result are discussed.


title: Electrodynamics of moving magnetoelectric media: variational approach

abstract:
  Recently, Feigel has predicted a new effect in magnetoelectric media. The
theoretical evaluation of this effect requires a careful analysis of a dynamics
of the moving magnetoelectric medium and, in particular, the derivation of the
energy-momentum of the electromagnetic field in such a medium. Then, one can
proceed with the study of the wave propagation in this medium and derive the
mechanical quantities such as the energy, the momentum, and their fluxes and
the corresponding forces. In this paper, we develop a consistent
general-relativistic variational approach to the moving dielectric and magnetic
medium with and without magnetoelectric properties. The old experiments in
which the light pressure was measured in fluids are reanalysed in our new
framework.


title:
Antisymmetric-Tensor and Electromagnetic effects in an
  alpha'-non-perturbative Four-Dimensional String Cosmology

abstract:
  Starting from an exact (in the Regge slope alpha') functional method for a
bosonic stringy sigma-model, we investigate four-dimensional cosmological
string solutions in graviton, dilaton and antisymmetric tensor backgrounds,
compatible with world-sheet conformal invariance, and valid beyond perturbative
expansions in powers of alpha'. The antisymmetric tensor field, playing the
role of an axion in the four-dimensional target space time, leads to spatial
anisotropies of the emergent Robertson-Walker expanding Universe, and, upon
coupling the system to the electromagnetic field, it results in non-trivial
optical activity. Some estimates of the corresponding effects are made and
their relevance to current cosmology is briefly discussed.


title:
"Boundary blowup" type sub-solutions to semilinear elliptic equations
  with Hardy potential

abstract:
  Semilinear elliptic equations which give rise to solutions blowing up at the
boundary are perturbed by a Hardy potential. The size of this potential effects
the existence of a certain type of solutions (large solutions): if the
potential is too small, then no large solution exists. The presence of the
Hardy potential requires a new definition of large solutions, following the
pattern of the associated linear problem. Nonexistence and existence results
for different types of solutions will be given. Our considerations are based on
a Phragmen-Lindelof type theorem which enables us to classify the solutions and
sub-solutions according to their behavior near the boundary. Nonexistence
follows from this principle together with the Keller-Osserman upper bound. The
existence proofs rely on sub- and super-solution techniques and on estimates
for the Hardy constant derived in Marcus, Mizel and Pinchover.


title: pp Elastic Scattering at LHC in a Nucleon-Structure Model

abstract:
  We predict pp elastic differential cross sections at LHC at c.m. energy 14
TeV and momentum transfer range |t| = 0 - 10 GeV*2 in a nucleon-structure
model. In this model, the nucleon has an outer cloud of quark-antiquark
condensed ground state, an inner shell of topological baryonic charge (r ~
0.44F) probed by the vector meson omega, and a central quark-bag (r ~ 0.2F)
containing valence quarks. We also predict elastic differential cross section
in the Coulomb-hadronic interference region. Large |t| elastic scattering in
this model arises from valence quark-quark scattering, which is taken to be due
to the hard-pomeron (BFKL pomeron with next to leading order corrections). We
present results of taking into account multiple hard-pomeron exchanges, i.e.
unitarity corrections. Finally, we compare our prediction of pp elastic
differential cross section at LHC with the predictions of various other models.
Precise measurement of pp elastic differential cross section at LHC by the
TOTEM group in the |t| region 0 - 5 GeV*2 will be able to distinguish between
these models.


title:
Stability and instability of nonlinear defect states in the coupled mode
  equations -- analytical and numerical study

abstract:
  Coupled backward and forward wave amplitudes of an electromagnetic field
propagating in a periodic and nonlinear medium at Bragg resonance are governed
by the nonlinear coupled mode equations (NLCME). This system of PDEs, similar
in structure to the Dirac equations, has gap soliton solutions that travel at
any speed between 0 and the speed of light. A recently considered strategy for
spatial trapping or capture of gap optical soliton light pulses is based on the
appropriate design of localized defects in the periodic structure. Localized
defects in the periodic structure give rise to defect modes, which persist as
{\it nonlinear defect modes} as the amplitude is increased. Soliton trapping is
the transfer of incoming soliton energy to {\it nonlinear} defect modes. To
serve as targets for such energy transfer, nonlinear defect modes must be
stable. We therefore investigate the stability of nonlinear defect modes.
Resonance among discrete localized modes and radiation modes plays a role in
the mechanism for stability and instability, in a manner analogous to the
nonlinear Schr\"odinger / Gross-Pitaevskii (NLS/GP) equation. However, the
nature of instabilities and how energy is exchanged among modes is considerably
more complicated than for NLS/GP due, in part, to a continuous spectrum of
radiation modes which is unbounded above and below. In this paper we (a)
establish the instability of branches of nonlinear defect states which, for
vanishing amplitude, have a linearization with eigenvalue embedded within the
continuous spectrum, (b) numerically compute, using Evans function, the
linearized spectrum of nonlinear defect states of an interesting multiparameter
family of defects, and (c) perform direct time-dependent numerical simulations
in which we observe the exchange of energy among discrete and continuum modes.


title: V723 Cas (Nova Cassiopeiae 1995): MERLIN observations from 1996 to 2001

abstract:
  MERLIN observations of the unusually slow nova V723 Cas are presented. Nine
epochs of 6-cm data between 1996 and 2001 are mapped, showing the initial
expansion and brightening of the radio remnant, the development of structure
and the final decline. A radio light curve is presented and fitted by the
standard Hubble flow model for radio emission from novae in order to determine
the values of various physical parameters for the shell. The model is
consistent with the overall development of the radio emission. Assuming a
distance of 2.39 (+/-0.38) kpc and a shell temperature of 17000 K, the model
yields values for expansion velocity of 414 +/- 0.1 km s^-1 and shell mass of
1.13 +/- 0.04 * 10^-4 Msolar. These values are consistent with those derived
from other observations although the ejected masses are rather higher than
theoretical predictions. The structure of the shell is resolved by MERLIN and
shows that the assumption of spherical symmetry in the standard model is
unlikely to be correct.


title:
Efficiency of energy transfer in a light-harvesting system under quantum
  coherence

abstract:
  We investigate the role of quantum coherence in the efficiency of excitation
transfer in a ring-hub arrangement of interacting two-level systems, mimicking
a light-harvesting antenna connected to a reaction center as it is found in
natural photosynthetic systems. By using a quantum jump approach, we
demonstrate that in the presence of quantum coherent energy transfer and
energetic disorder, the efficiency of excitation transfer from the antenna to
the reaction center depends intimately on the quantum superposition properties
of the initial state. In particular, we find that efficiency is sensitive to
symmetric and asymmetric superposition of states in the basis of localized
excitations, indicating that initial state properties can be used as a
efficiency control parameter at low temperatures.


title:
Quaternion CR-submanifolds of a Locally Conformal Quaternion Kaehler
  Manifold

abstract:
  The purpose of the present paper is to study the differential geometric
properties of a quaternion CR-submanifold in a locally conformal quaternion
Kaehler manifold.


title: A threshold-improved narrow-width approximation for BSM physics

abstract:
  A modified narrow-width approximation that allows for O(Gamma/M)-accurate
predictions for resonant particle decay with similar intermediate masses is
proposed and applied to MSSM processes to demonstrate its importance for
searches for particle physics beyond the Standard Model.


title: Small-Angle CMB Temperature Anisotropies Induced by Cosmic Strings

abstract:
  We use Nambu-Goto numerical simulations to compute the cosmic microwave
background (CMB) temperature anisotropies induced at arcminute angular scales
by a network of cosmic strings in a Friedmann-Lemaitre-Robertson-Walker (FLRW)
expanding universe. We generate 84 statistically independent maps on a 7.2
degree field of view, which we use to derive basic statistical estimators such
as the one-point distribution and two-point correlation functions. At high
multipoles, the mean angular power spectrum of string-induced CMB temperature
anisotropies can be described by a power law slowly decaying as \ell^{-p}, with
p=0.889 (+0.001,-0.090) (including only systematic errors). Such a behavior
suggests that a nonvanishing string contribution to the overall CMB
anisotropies may become the dominant source of fluctuations at small angular
scales. We therefore discuss how well the temperature gradient magnitude
operator can trace strings in the context of a typical arcminute
diffraction-limited experiment. Including both the thermal and nonlinear
kinetic Sunyaev-Zel'dovich effects, the Ostriker-Vishniac effect, and the
currently favored adiabatic primary anisotropies, we find that, on such a map,
strings should be ``eye visible,'' with at least of order ten distinctive
string features observable on a 7.2 degree gradient map, for tensions U down to
GU \simeq 2 x 10^{-7} (in Planck units). This suggests that, with upcoming
experiments such as the Atacama Cosmology Telescope (ACT), optimal
non-Gaussian, string-devoted statistical estimators applied to small-angle CMB
temperature or gradient maps may put stringent constraints on a possible cosmic
string contribution to the CMB anisotropies.


title: How (Not) to Palatini

abstract:
  We revisit the problem of defining non-minimal gravity in the first order
formalism. Specializing to scalar-tensor theories, which may be disguised as
`higher-derivative' models with the gravitational Lagrangians that depend only
on the Ricci scalar, we show how to recast these theories as Palatini-like
gravities. The correct formulation utilizes the Lagrange multiplier method,
which preserves the canonical structure of the theory, and yields the
conventional metric scalar-tensor gravity. We explain the discrepancies between
the na\"ive Palatini and the Lagrange multiplier approach, showing that the
na\"ive Palatini approach really swaps the theory for another. The differences
disappear only in the limit of ordinary General Relativity, where an accidental
redundancy ensures that the na\"ive Palatini works there. We outline the
correct decoupling limits and the strong coupling regimes. As a corollary we
find that the so-called `Modified Source Gravity' models suffer from strong
coupling problems at very low scales, and hence cannot be a realistic
approximation of our universe. We also comment on a method to decouple the
extra scalar using the chameleon mechanism.


title: The IMF of simple and composite populations

abstract:
  The combination of a finite time-scale for star formation, rapid early
stellar evolution and rapid stellar-dynamical processes imply that the stellar
IMF cannot be inferred for any star cluster independently of its age (the
Cluster IMF Theorem). The IMF can nevertheless be constrained statistically by
evolving many theoretical populations drawn from one parent distribution and
testing these against observed populations. It follows that all known
well-resolved stellar populations are consistent with having been drawn from
the same parent mass distribution. The IMF Universality Hypothesis therefore
cannot be discarded despite the existence of the Cluster IMF Theorem. This
means that the currently existing star-formation theory fails to describe the
stellar outcome, because it predicts a dependency of the IMF on the physical
boundary conditions not observed. The IGIMF Theorem, however, predicts a
variation of galaxy-wide IMFs in dependence of the galaxy's star-formation rate
even if the IMF Universality Hypothesis is valid. This variation has now been
observed in SDSS galaxy data. Detailed analysis of the binary properties in the
very-low-mass star and brown dwarf (BD) mass regime on the one hand, and in the
stellar regime on the other, shows there to be a discontinuity in the IMF near
0.1Msun such that BDs follow a separate distribution function. Very recent
observations of the stellar population within 1pc of the nucleus of the MW do
suggest a top-heavy IMF, perhaps hinting at a variation of the star-formation
outcome with tidal field and temperature thereby violating the IMF Universality
Hypothesis under these physically extreme conditions. Another violation of this
hypothesis appears to emerge for extremely metal-poor stars such that the
primordial IMF appears to have been depleted in low-mass stars.


title: Lieb-Thirring inequalities with improved constants

abstract:
  Following Eden and Foias we obtain a matrix version of a generalised Sobolev
inequality in one-dimension. This allow us to improve on the known estimates of
best constants in Lieb-Thirring inequalities for the sum of the negative
eigenvalues for multi-dimensional Schroedinger operators.


title:
Global Properties of the Globular Cluster Systems of Four Spiral
  Galaxies

abstract:
  We present results from a wide-field imaging study of the globular cluster
(GC) systems of a sample of edge-on, Sb-Sc spiral galaxies ~7-20 Mpc away. This
study is part of a larger survey of the ensemble properties of the GC
populations of giant galaxies. We imaged the galaxies in BVR filters with
large-format CCD detectors on the WIYN 3.5-m telescope, to projected radii of
~20-40 kpc. For four galaxies (NGC 2683, NGC 3556, NGC 4157, and NGC 7331), we
quantify the radial distributions of the GC systems and estimate the total
number, luminosity- and mass-normalized specific frequencies (S_N and T), and
blue (metal-poor) fraction of GCs. A fifth galaxy (NGC 3044) was apparently too
distant for us to have detected its GC system. Our S_N for NGC 2683 is 2.5
times smaller than the previously-published value, likely due in part to
reduced contamination from non-GCs. For the spiral galaxies analyzed for the
survey to date, the average number of GCs is 170+/-40 and the weighted mean
values of S_N and T are 0.8+/-0.2 and 1.4+/-0.3. We use the survey data to
derive a relationship between radial exent of the GC system and host galaxy
mass over a factor of 20 in mass. Finally, we confirm the trend, identified in
previous survey papers, of increasing specific frequency of metal-poor GCs with
increasing galaxy mass. We compare the data with predictions from a simple
model and show that carefully quantifying the numbers of metal-poor GCs in
galaxies can constrain the formation redshifts of the GCs and their host
galaxies.


title:
On the Newtonian origin of the spin motive force in ferromagnetic atomic
  wires

abstract:
  We demonstrate numerically the existence of a spin-motive force acting on
spin-carriers when moving in a time and space dependent internal field. This is
the case of electrons in a one-dimensional wires with a precessing domain wall.
The effect can be explained solely by considering adiabatic dynamics and it is
shown to exist for both classical and quantum systems.


title: Anisotropic Cosmological Constant and the CMB Quadrupole Anomaly

abstract:
  There are evidences that the cosmic microwave background (CMB) large-angle
anomalies imply a departure from statistical isotropy and hence from the
standard cosmological model. We propose a LCDM model extension whose dark
energy component preserves its nondynamical character but wield anisotropic
vacuum pressure. Exact solutions for the cosmological scale factors are
presented, upper bounds for the deformation parameter are evaluated and its
value is estimated considering the elliptical universe proposal to solve the
quadrupole anomaly. This model can be constructed from a Bianchi I cosmology
with cosmological constant from two different ways: i) a straightforward
anisotropic modification of the vacuum pressure consistently with
energy-momentum conservation; ii) a Poisson structure deformation between
canonical momenta such that the dynamics remain invariant under scale factors
rescalings.


title: On the Ernst electro-vacuum equations and ergosurfaces

abstract:
  The question of smoothness at the ergosurface of the space-time metric
constructed out of solutions (E,phi) of the Ernst electro-vacuum equations is
considered. We prove smoothness of those ergosurfaces at which Re(E) provides
the dominant contribution to f=-(Re(E)+|phi|^2) at the zero-level-set of f.
Some partial results are obtained in the remaining cases: in particular we give
examples of leading-order solutions with singular isolated "ergocircles".


title:
Magnetic properties of Gd_xY_{1-x}Fe_2Zn_{20}: dilute, large, $\textbf
  {S}$ moments in a nearly ferromagnetic Fermi liquid

abstract:
  Single crystals of the dilute, rare earth bearing, pseudo-ternary series,
Gd_xY_{1-x}Fe_2Zn_{20} were grown out of Zn-rich solution. Measurements of
magnetization, resistivity and heat capacity on Gd_xY_{1-x}Fe_2Zn_{20} samples
reveal ferromagnetic order of Gd^{3+} local moments across virtually the whole
series ($x \geq 0.02$). The magnetic properties of this series, including the
ferromagnetic ordering, the reduced saturated moments at base temperature, the
deviation of the susceptibilities from Curie-Weiss law and the anomalies in the
resistivity, are understood within the frame work of dilute, $\textbf {S}$
moments (Gd^{3+}) embedded in a nearly ferromagnetic Fermi liquid
(YFe_2Zn_{20}). The s-d model is employed to further explain the variation of
$T_{\mathrm{C}}$ with x as well as the temperature dependences of of the
susceptibilities.


title:
On the spinor structure of the homogeneous and isotropic universe in
  closed model

abstract:
  The closed homogeneous and isotropic universe is considered. The bundles of
Weyl and Dirac spinors for this universe are explicitly described. Some
explicit formulas for the basic fields and for the connection components in
stereographic and in spherical coordinates are presented.


title:
A Constraint on Z_\odot from Fits of Isochrones to the Color-Magnitude
  Diagram of M67

abstract:
  The mass at which a transition is made between stars that have radiative or
convective cores throughout the core H-burning phase is a fairly sensitive
function of Z (particularly the CNO abundances). As a consequence, the ~4 Gyr,
open cluster M67 provides a constraint on Z_\odot (and the solar heavy-element
mixture) because (i) high-resolution spectroscopy indicates that this system
has virtually the same metal abundances as the Sun, and (ii) its turnoff stars
have masses just above the lower limit for sustained core convection on the
main sequence. In this study, evolutionary tracks and isochrones using the
latest MARCS model atmospheres as boundary conditions have been computed for
0.6-1.4 solar masses on the assumption of a metals mix (implying Z_\odot =
0.0125) based on the solar abundances derived by M. Asplund and collaborators
using 3-D model atmospheres. These calculations do not predict a turnoff gap
where one is observed in M67. No such difficulty is found if the analysis uses
isochrones for Z_\odot = 0.0165, assuming the Grevesse & Sauval (1998) mix of
heavy elements. Our findings, like the inferences from helioseismology,
indicate a problem with the Asplund et al. abundances. However, it is possible
that low-Z models with diffusive processes taken into account will be less
problematic.


title: A Map-Based Model of the Cardiac Action Potential

abstract:
  A discrete time model that is capable of replicating the basic features of
cardiac cell action potentials is suggested. The paper shows how the map-based
approaches can be used to design highly efficient computational models
(algorithms) that enable large-scale simulations and analysis of discrete
network models of cardiac activity.


title:
On some lower bounds on the number of bicliques needed to cover a
  bipartite graph

abstract:
  The biclique covering number of a bipartite graph G is the minimum number of
complete bipartite subgraphs (bicliques) whose union contains every edge of G.
  In this little note we compare three lower bounds on the biclique covering
number: A bound jk(G) proposed by Jukna & Kulikov (Discrete Math. 2009); the
well-known fooling set bound fool(G); the "tensor-power" fooling set bound
fool^\infty(G). We show jk \le fool le fool^\infty \le min_Q (rk Q)^2, where
the minimum is taken over all matrices with a certain zero/nonzero-pattern.
Only the first inequality is really novel, the third one generalizes a result
of Dietzfelbinger, Hromkovi\v{c}, Schnitger (1994).
  We also give examples for which fool \ge (rk)^{log_4 6} improving on
Dietzfelbinger et al.


title: Relating the thermodynamic arrow of time to the causal arrow

abstract:
  Consider a Hamiltonian system that consists of a slow subsystem S and a fast
subsystem F. The autonomous dynamics of S is driven by an effective
Hamiltonian, but its thermodynamics is unexpected. We show that a well-defined
thermodynamic arrow of time (second law) emerges for S whenever there is a
well-defined causal arrow from S to F and the back-action is negligible. This
is because the back-action of F on S is described by a non-globally Hamiltonian
Born-Oppenheimer term that violates the Liouville theorem, and makes the second
law inapplicable to S. If S and F are mixing, under the causal arrow condition
they are described by microcanonic distributions P(S) and P(S|F). Their
structure supports a causal inference principle proposed recently in machine
learning.


title: Clumping in the winds of O-type CSPNs

abstract:
  Recent studies of massive O-type stars present clear evidences of
inhomogeneous and clumped winds. O-type (H-rich) central stars of planetary
nebulae (CSPNs) are in some ways the low mass-low luminosity analogous of those
massive stars. In this contribution, we present preliminary results of our
on-going multi-wavelength (FUV, UV and optical) study of the winds of Galactic
CSPNs. Particular emphasis will be given to the clumping factors derived by
means of optical lines (Halpha and HeII4686) and "classic" FUV (and UV) lines.


title:
Simulations and interpretation of the 6-cm MERLIN images of the
  classical nova V723 Cas

abstract:
  We compare the predictions of simple models for the radio emission from
classical novae with the MERLIN radio observations of nova V723 Cas (Nova Cas
1995). Spherically symmetric and ellipsoidal radiative transfer models are
implemented in order to generate synthetic emission maps. These are then
convolved with an accurate representation of the uv coverage of MERLIN. The
parameters and geometry of the shell model are based on those returned by
fitting models to the observed light curve. This allows direct comparison of
the model images with the nine 6-cm MERLIN images of V723 Cas. It is found that
the seemingly complex structure (clumping, apparent rotation) evident in the
observations can actually be reproduced with a simple spherical emission model.
The simulations showthat a 24-h track greatly reduces the instrumental effects
and the synthetic radio map is a closer representation of the true (model) sky
brightness distribution. It is clear that interferometric arrays with sparse uv
coverage (e.g. MERLIN, VLBA) will be more prone to these instrumental effects
especially when imaging ring-like objects with time-dependent structure
variations. A modelling approach such as that adopted here is essential when
interpreting observations.


title:
The periodic table of n-categories for low dimensions I: degenerate
  categories and degenerate bicategories

abstract:
  We examine the periodic table of weak n-categories for the low-dimensional
cases. It is widely understood that degenerate categories give rise to monoids,
doubly degenerate bicategories to commutative monoids, and degenerate
bicategories to monoidal categories; however, to understand this correspondence
fully we examine the totalities of such structures together with maps between
them and higher maps between those. Categories naturally form a 2-category
{\bfseries Cat} so we take the full sub-2-category of this whose 0-cells are
the degenerate categories. Monoids naturally form a category, but we regard
this as a discrete 2-category to make the comparison. We show that this
construction does not yield a biequivalence; to get an equivalence we ignore
the natural transformations and consider only the {\it category} of degenerate
categories. A similar situation occurs for degenerate bicategories. The
tricategory of such does not yield an equivalence with monoidal categories; we
must consider only the categories of such structures. For doubly degenerate
bicategories the tricategory of such is not naturally triequivalent to the
category of commutative monoids (regarded as a tricategory). However in this
case considering just the categories does not give an equivalence either; to
get an equivalence we consider the {\it bicategory} of doubly degenerate
bicategories. We conclude with a hypothesis about how the above cases might
generalise for n-fold degenerate n-categories.


title:
Diversity-Multiplexing Tradeoff of Asynchronous Cooperative Diversity in
  Wireless Networks

abstract:
  Synchronization of relay nodes is an important and critical issue in
exploiting cooperative diversity in wireless networks. In this paper, two
asynchronous cooperative diversity schemes are proposed, namely, distributed
delay diversity and asynchronous space-time coded cooperative diversity
schemes. In terms of the overall diversity-multiplexing (DM) tradeoff function,
we show that the proposed independent coding based distributed delay diversity
and asynchronous space-time coded cooperative diversity schemes achieve the
same performance as the synchronous space-time coded approach which requires an
accurate symbol-level timing synchronization to ensure signals arriving at the
destination from different relay nodes are perfectly synchronized. This
demonstrates diversity order is maintained even at the presence of asynchronism
between relay node. Moreover, when all relay nodes succeed in decoding the
source information, the asynchronous space-time coded approach is capable of
achieving better DM-tradeoff than synchronous schemes and performs equivalently
to transmitting information through a parallel fading channel as far as the
DM-tradeoff is concerned. Our results suggest the benefits of fully exploiting
the space-time degrees of freedom in multiple antenna systems by employing
asynchronous space-time codes even in a frequency flat fading channel. In
addition, it is shown asynchronous space-time coded systems are able to achieve
higher mutual information than synchronous space-time coded systems for any
finite signal-to-noise-ratio (SNR) when properly selected baseband waveforms
are employed.


title: Light Curves of Radio Supernovae

abstract:
  We present the results from the on-going radio monitoring of recent type II
supernovae (SNe), including SNe 2004et, 2004dj, 2002hh, 2001em, and 2001gd.
Using the Very Large Array to monitor these supernovae, we present their radio
light-curves. From these data we are able to discuss parameterizations and
modeling and make predictions of the nature of the progenitors based on
previous research. Derived mass loss rates assume wind-established
circumstellar medium, shock velocity ~10,000 km/s, wind velocity ~10 km/s, and
CSM Temperature ~10,000 K.


title: One-Electron Physics of the Actinides

abstract:
  We present a detailed analysis of the one-electron physics of the actinides.
Various LMTO basis sets are analyzed in order to determine a robust bare
Hamiltonian for the actinides. The hybridization between f- an spd- states is
compared with the f-f hopping in order to understand the Anderson-like and
Hubbard-like contributions to itineracy in the actinides. We show that both
contributions decrease strongly as one move from the light actinides to the
heavy actinides, while the Anderson-like contribution dominates in all cases. A
real-space analysis of the band structure shows that nearest-neighbor hopping
dominates the physics in these materials. Finally, we discuss the implications
of our results to the delocalization transition as function of atomic number
across the actinide series.


title: Recent Type II Radio Supernovae

abstract:
  We present the results of radio observations, taken primarily with the Very
Large Array, of Supernovae 1993J, 2001gd, 2001em, 2002hh, 2004dj, and 2004et.
We have fit a parameterized model to the multi-frequency observations of each
supernova. We compare the observed and derived radio properties of these
supernovae by optical classification and discuss the implications.


title: DLAs and Galaxy Formation

abstract:
  Damped Lyman-alpha systems (DLAs) are useful probes of star formation and
galaxy formation at high redshift. We study the physical properties of DLAs and
their relationship to Lyman-break galaxies using cosmological hydrodynamic
simulations based on the concordance Lambda cold dark matter model. Fundamental
statistics such as global neutral hydrogen (HI) mass density, HI column density
distribution function, DLA rate-of-incidence and mean halo mass of DLAs are
reproduced reasonably well by the simulations, but with some deviations that
need to be understood better in the future. We discuss the feedback effects by
supernovae and galactic winds on the DLA distribution. We also compute the
[C_II] emission from neutral gas in high-z galaxies, and make predictions for
the future observations by ALMA and SPICA. Agreement and disagreement between
simulations and observations are discussed, as well as the future directions of
our DLA research.


title: Trace fields and commensurability of link complements

abstract:
  This paper investigates the strength of the trace field as a commensurability
invariant of hyperbolic 3-manifolds. We construct an infinite family of
two-component hyperbolic link complements which are pairwise incommensurable
and have the same trace field, and infinitely many 1-cusped finite volume
hyperbolic 3-manifolds with the same property. We also show that the
two-component link complements above have integral traces, but each has a
mutant with a nonintegral trace.


title:
Weighted-$L^\infty$ and pointwise space-time decay estimates for wave
  equations with potentials and initial data of low regularity

abstract:
  We prove weighted-$L^\infty$ and pointwise space-time decay estimates for
weak solutions of a class of wave equations with time-independent potentials
and subject to initial data, both of low regularity, satisfying given decay
bounds at infinity. The rate of their decay depends on the asymptotic behaviour
of the potential and of the data. The technique is robust enough to treat also
more regular solutions and provides decay estimates for arbitrary derivatives,
provided the potential and the data have sufficient regularity, but it is
restricted to potentials of bounded strength (such that $-\Delta-|V|$ has no
negative eigenvalues).


title:
Proper Motions of OH Masers and Magnetic Fields in Massive Star-Forming
  Regions

abstract:
  We present data of proper motions of OH masers in the massive star-forming
regions ON 1, K3-50, and W51 Main/South. OH maser motions in ON 1 are
consistent with expansion at approximately 5 km/s, likely tracing the expanding
ultracompact H II region. Motions in K3-50 are faster and may be indicating the
final stages of OH maser emission in the source, before the OH masers turn off
as the H II region transitions from the ultracompact to the compact phase. W51
South shows indications of aspherical expansion, while motions in W51 Main are
more difficult to interpret. Nevertheless, it appears that the relative
projected separation between W51 Main and W51 South is decreasing,
corresponding to an estimate of enclosed mass of at least 1500 solar masses,
consistent with estimates derived from millimeter-wavelength dust emission. We
confirm the ~20 mG magnetic fields previously seen in W51 Main, which may
represent the upper end of the density range allowable for 1665 MHz maser
emission. Magnetic field strengths and directions, obtained from Zeeman
splitting, in each source are consistent with values obtained in the first
epoch four to nine years ago.


title:
The generalized Abel-Plana formula with applications to Bessel functions
  and Casimir effect

abstract:
  One of the most efficient methods for the evaluation of the vacuum
expectation values for physical observables in the Casimir effect is based on
using the Abel-Plana summation formula. This enables to derive the renormalized
quantities in a manifestly cutoff independent way and to present them in the
form of strongly convergent integrals. However, applications of the Abel-Plana
formula, in its usual form, are restricted by simple geometries when the
eigenmodes have a simple dependence on quantum numbers. The author generalized
the Abel-Plana formula which essentially enlarges its application range. Based
on this generalization, formulae have been obtained for various types of series
over the zeros of combinations of Bessel functions and for integrals involving
these functions. It has been shown that these results generalize the special
cases existing in literature. Further, the derived summation formulae have been
used to summarize series arising in the direct mode summation approach to the
Casimir effect for spherically and cylindrically symmetric boundaries, for
boundaries moving with uniform proper acceleration, and in various braneworld
scenarios. This allows to extract from the vacuum expectation values of local
physical observables the parts corresponding to the geometry without boundaries
and to present the boundary-induced parts in terms of integrals strongly
convergent for the points away from the boundaries. As a result, the
renormalization procedure for these observables is reduced to the corresponding
procedure for bulks without boundaries. The present paper reviews these
results. We also aim to collect the results on vacuum expectation values for
local physical observables such as the field square and the energy-momentum
tensor in manifolds with boundaries for various bulk and boundary geometries.


title:
On the Use of Blanketed Atmospheres as Boundary Conditions for Stellar
  Evolutionary Models

abstract:
  Stellar models have been computed for stars having [Fe/H] = 0.0 and -2.0 to
determine the effects of using boundary conditions derived from the latest
MARCS model atmospheres. The latter were fitted to the interior models at both
the photosphere and at tau = 100, and at least for the 0.8-1.0 solar mass stars
considered here, the resultant evolutionary tracks were found to be nearly
independent of the chosen fitting point. Particular care was taken to treat the
entire star as consistently as possible; i.e., both the interior and atmosphere
codes assumed the same abundances and the same treatment of convection. Tracks
were also computed using either the classical gray T(tau,T_eff) relation or
that derived by Krishna Swamy (1966) to derive the boundary pressure. The
latter predict warmer giant branches (by ~150 K) at solar abundances than those
based on gray or MARCS atmospheres, which happens to be in good agreement with
the inferred temperatures of giants in the open cluster M67 from the latest
(V-K)-T_eff relations. Most of the calculations assumed Z=0.0125 (Asplund et
al.), though a few models were computed for Z=0.0165 (Grevesse & Sauval) to
determine the dependence of the tracks on Z_\odot. Grids of "scaled solar,
differentially corrected" (SDC) atmospheres were also computed to try to
improve upon theoretical MARCS models. When they were used as boundary
conditions, the resultant tracks agreed very well with those based on a
standard scaled-solar (e.g., Krishna Swamy) T(tau,T_eff) relation,
independently of the assumed metal abundance. Fits of isochrones to the C-M
diagram of the [Fe/H] = -2 globular cluster M68 were examined, as was the
possibility that the mixing-length parameter varies with stellar parameters.


title: Avalanche statistics and time-resolved grain dynamics for a driven heap

abstract:
  We probe the dynamics of intermittent avalanches caused by steady addition of
grains to a quasi-two dimensional heap. To characterize the time-dependent
average avalanche flow speed v(t), we image the top free surface. To
characterize the grain fluctuation speed dv(t), we use Speckle-Visibility
Spectroscopy. During an avalanche, we find that the fluctuation speed is
approximately one-tenth the average flow speed, and that these speeds are
largest near the beginning of an event. We also find that the distribution of
event durations is peaked, and that event sizes are correlated with the time
interval since the end of the previous event. At high rates of grain addition,
where successive avalanches merge into smooth continuous flow, the relationship
between average and fluctuation speeds changes to dv Sqrt[v].


title: A Parameterized Post-Friedmann Framework for Modified Gravity

abstract:
  We develop a parameterized post-Friedmann (PPF) framework which describes
three regimes of modified gravity models that accelerate the expansion without
dark energy. On large scales, the evolution of scalar metric and density
perturbations must be compatible with the expansion history defined by distance
measures. On intermediate scales in the linear regime, they form a
scalar-tensor theory with a modified Poisson equation. On small scales in dark
matter halos such as our own galaxy, modifications must be suppressed in order
to satisfy stringent local tests of general relativity. We describe these
regimes with three free functions and two parameters: the relationship between
the two metric fluctuations, the large and intermediate scale relationships to
density fluctuations and the two scales of the transitions between the regimes.
We also clarify the formal equivalence of modified gravity and generalized dark
energy. The PPF description of linear fluctuation in f(R) modified action and
the Dvali-Gabadadze-Porrati braneworld models show excellent agreement with
explicit calculations. Lacking cosmological simulations of these models, our
non-linear halo-model description remains an ansatz but one that enables
well-motivated consistency tests of general relativity. The required
suppression of modifications within dark matter halos suggests that the linear
and weakly non-linear regimes are better suited for making complementary test
of general relativity than the deeply non-linear regime.


title: Community Structure in Congressional Cosponsorship Networks

abstract:
  We study the United States Congress by constructing networks between Members
of Congress based on the legislation that they cosponsor. Using the concept of
modularity, we identify the community structure of Congressmen, as connected
via sponsorship/cosponsorship of the same legislation, to investigate the
collaborative communities of legislators in both chambers of Congress. This
analysis yields an explicit and conceptually clear measure of political
polarization, demonstrating a sharp increase in partisan polarization which
preceded and then culminated in the 104th Congress (1995-1996), when
Republicans took control of both chambers. Although polarization has since
waned in the U.S. Senate, it remains at historically high levels in the House
of Representatives.


title: The hardness of computing an eigenform

abstract:
  In this article, we give evidence that computing Fourier coefficients of the
Hecke eigenforms for composite indices is no easier than factoring integers. In
particular, we show that the existence of a polynomial time algorithm that,
given n, computes the n-th Fourier coefficient of a (fixed) Hecke eigenform
implies that we can factor most RSA moduli (numbers that are products of two
distinct primes) in polynomial time.


title: A Selberg integral for the Lie algebra A_n

abstract:
  A new q-binomial theorem for Macdonald polynomials is employed to prove an
A_n analogue of the celebrated Selberg integral. This confirms the g=A_n case
of a conjecture by Mukhin and Varchenko concerning the existence of a Selberg
integral for every simple Lie algebra g.


title:
Influence of exciton-exciton correlations on the polarization
  characteristics of the polariton amplification in semiconductor microcavities

abstract:
  Based on a microscopic many-particle theory we investigate the influence of
excitonic correlations on the vectorial polarization state characteristics of
the parametric amplification of polaritons in semiconductor microcavities. We
study a microcavity with perfect in-plane isotropy. A linear stability analysis
of the cavity polariton dynamics shows that in the co-linear (TE-TE or TM-TM)
pump-probe polarization state configuration, excitonic correlations diminish
the parametric scattering process whereas it is enhanced by excitonic
correlations in the cross-linear (TE-TM or TM-TE) configuration. Without any
free parameters, our microscopic theory gives a quantitative understanding how
many-particle effects can lead to a rotation or change of the outgoing
(amplified) probe signal's vectorial polarization state relative to the
incoming one's.