title: Flow, Ordering and Jamming of Sheared Granular Suspensions

abstract:
  We study the rheological properties of a granular suspension subject to
constant shear stress by constant volume molecular dynamics simulations. We
derive the system `flow diagram' in the volume fraction/stress plane
$(\phi,F)$: at low $\phi$ the flow is disordered, with the viscosity obeying a
Bagnold-like scaling only at small $F$ and diverging as the jamming point is
approached; if the shear stress is strong enough, at higher $\phi$ an ordered
flow regime is found, the order/disorder transition being marked by a sharp
drop of the viscosity. A broad jamming region is also observed where, in
analogy with the glassy region of thermal systems, slow dynamics followed by
kinetic arrest occurs when the ordering transition is prevented.


title: Frobenius polynomials for Calabi-Yau equations

abstract:
  We describe a variation of Dworks unit-root method to determine the degree
four Frobenius polynomial for members of a 1-modulus Calabi-Yau family over
$\mathbb{P}^1$ in terms of the holomorphic period near a point of maximal
unipotent monodromy. The method is illustrated on a couple of examples.


title: Formation and Evolution of W UMa Stars: Fallacies and Corrections

abstract:
  The period histograms of eclipsing binaries generated with ASAS data cannot
only be interpreted by orbital evolution. The eclipse probabilities, selection
effects and space distributions in the solar neighborhood should be considered
before any interpretations are made. Depending upon physical dimensions (total
mass and period) of the progenitor stars and the efficiency of angular momentum
loss (AML) mechanism, a newly formed W UMa type binary can be at any age up to
several Gyr, and evolution in the contact stage is controlled not only by
angular momentum and mass loss but also by mass transfer between the component
stars. Thus, mean life of contact stages should be about 1.6 Gyr. A different
time scale would cause inconsistencies.


title:
The role of the $qqqq\bar{q}$ components in the electromagnetic
  transition $\gamma^*N\to N^*(1535)$

abstract:
  The helicity amplitudes $A^{p}_{1/2}$ and $S^{p}_{1/2}$ for the
electromagnetic transition $\gamma^{*} N\to N^{*}(1535)$ are calculated in the
quark model that is extended to include the lowest lying $qqqq\bar{q}$
components in addition to the $qqq$ component. It is found that with admixture
of 5-quark components with a proportion of 20% in the nucleon and 25-65% in the
$N^{*}(1535)$ resonance the calculated helicity amplitude $A^{p}_{1/2}$
decreases at the photon point, $Q^{2}=0$ to the empirical range. The
$qqqq\bar{q}$ components contain $s\bar s$ pairs, which is consistent with the
substantial width for $N\eta$ decay of the $N^{*}(1535)$. The best description
of the momentum dependence of the empirical helicity amplitudes is obtained by
assuming that the $qqqq\bar{q}$ components are more compact than the $qqq$
component. However, this version of extended quark model still does not lead to
a satisfactory simultaneous description of both $A^{p}_{1/2}$ and $S^{p}_{1/2}$
although with significant improvement.


title: Spiral and Bar Instabilities Provoked by Dark Matter Satellites

abstract:
  We explore the secular dynamical evolution of an N-body model of M31 in the
presence of a population of 100 dark matter satellites over 10 Gyr. The
satellite population has structural and kinematic characteristics modelled to
follow the predictions of Lambda-CDM cosmological simulations. Vertical disk
heating is a small effect despite many interactions with the satellite
population with only a 20% increase in vertical velocity dispersion sigma_z and
the disk scale height z_d at the equivalent solar radius R = 2.5R_d . However,
the stellar disk is noticeably flared after 10 Gyr with z_d nearly doubling at
the disk edge. Azimuthal disk heating is much larger with sigma_R and sigma_z
both increasing by 1.7x. However, in a control experiment without satellites
dispersion increases by 1.5x suggesting that most of the effect is due to
heating through scattering off of spiral structure excited by swing-amplified
noise. Surprisingly, direct impacts of satellites on the disk can excite spiral
structure with a significant amplitude and in some cases impacts close to the
disk center also induce the bar instability. The large number of dark matter
satellite impacts expected over a galaxy's lifetime may be a significant source
of external perturbations for driving disk secular evolution.


title: In Search Of Graphane -- A two-dimensional hydrocarbon

abstract:
  The characteristic results by different diagnostics on a typical hydrogenated
diamond like carbon (HDLC) film synthesized directly in a capacitatively
coupled RF (13.56 MHz) discharge are described. The results show some typical
charecteric features of Graphane as predicted theoretically. First experimental
observation of GRAPHANE/GRAPHANE like structure embedded in the HDLC film is
described.


title: Relativistic Mean-Field Model with Scaled Hadron Masses and Couplings

abstract:
  Here we continue to elaborate properties of the relativistic mean-field based
model (SHMC) proposed in ref. [6] where hadron masses and coupling constants
depend on the $\sigma$-meson field. The validity of approximations used in [6]
is discussed. We additionally incorporate contribution of meson excitations to
the equations of motion. We also estimate the effects of the particle width. It
is demonstrated that the inclusion of the baryon-baryon hole and
baryon-antibaryon loop terms, if performed perturbatively, destroys the
consistency of the model.


title: Properties of $J/\psi$ at $T_c$: QCD second-order Stark effect

abstract:
  Starting from the temperature dependence of the energy density and pressure
from lattice QCD calculation, we extract the temperature dependence of the
electric and magnetic condensate near $T_c$. While the magnetic condensate
hardly changes across $T_c$, we find that the electric condensate increases
abruptly above $T_c$. This induces a small but an equally abrupt decrease in
the mass of $J/\psi$, can be calculated through the second-order Stark effect.
Combining the present result with the previously determined QCD sum rule
constraint, we extract the thermal width of $J/\psi$ above $T_c$, which also
increases fast. These changes can be identified as the critical behavior of
$J/\psi$ across $T_c$ associated with the phase transition. We find that the
mass shift and with broadening of $J/\psi$ at 1.05 $T_c$ will be around -100
MeV and 100 MeV respectively.


title:
The elliptic Hall algebra, Cherednick Hecke algebras and Macdonald
  polynomials

abstract:
  We show that the Hall algebra of the category of coherent sheaves on an
elliptic curve (or, equivalently, the algebra of unramified automorphic forms
for GL(n) for all n) is equal to the stable limit of spherical double affine
Hecke algebras for GL(k) as k goes to infinity. The two parameters correspond
to the size of the finite field and the modulus of the elliptc curve. Under
this isomorphism the Hecke operators are mapped to the Macdonald operators.
This allows us to give a geometric construction of Macdonald polynomials
(eigenvectors for the Macdonald operator) in terms of a suitable specialization
of Eisenstein series (eigenvectors for the Hecke operators).


title: Sensing Danger: Innate Immunology for Intrusion Detection

abstract:
  The immune system provides an ideal metaphor for anomaly detection in general
and computer security in particular. Based on this idea, artificial immune
systems have been used for a number of years for intrusion detection,
unfortunately so far with little success. However, these previous systems were
largely based on immunological theory from the 1970s and 1980s and over the
last decade our understanding of immunological processes has vastly improved.
In this paper we present two new immune inspired algorithms based on the latest
immunological discoveries, such as the behaviour of Dendritic Cells. The
resultant algorithms are applied to real world intrusion problems and show
encouraging results. Overall, we believe there is a bright future for these
next generation artificial immune algorithms.


title: Modeling of diffuse molecular gas applied to HD 102065 observations

abstract:
  Aims. We model a diffuse molecular cloud present along the line of sight to
the star HD 102065. We compare our modeling with observations to test our
understanding of physical conditions and chemistry in diffuse molecular clouds.
Methods. We analyze an extensive set of spectroscopic observations which
characterize the diffuse molecular cloud observed toward HD 102065. Absorption
observations provide the extinction curve, H2, C I, CO, CH, and CH+ column
densities and excitation. These data are complemented by observations of CII,
CO and dust emission. Physical conditions are determined using the Meudon PDR
model of UV illuminated gas. Results. We find that all observational results,
except column densities of CH, CH+ and H2 in its excited (J > 2) levels, are
consistent with a cloud model implying a Galactic radiation field (G~0.4 in
Draine's unit), a density of 80 cm-3 and a temperature (60-80 K) set by the
equilibrium between heating and cooling processes. To account for excited (J
>2) H2 levels column densities, an additional component of warm (~ 250K) and
dense (nH>10^4 cm-3) gas within 0.03 pc of the star would be required. This
solution reproduces the observations only if the ortho-to-para H2 ratio at
formation is 1. In view of the extreme physical conditions and the unsupported
requirement on the ortho-to-para ratio, we conclude that H2 excitation is most
likely to be accounted for by the presence of warm molecular gas within the
diffuse cloud heated by the local dissipation of turbulent kinetic energy. This
warm H2 is required to account for the CH+ column density. It could also
contribute to the CH abundance and explain the inhomogeneity of the CO
abundance indicated by the comparison of absorption and emission spectra.


title: IRS 13N: a new comoving group of sources at the Galactic Center

abstract:
  Context: The Galactic Center IRS 13E cluster is located ~3.2'' from SgrA*. It
is an extremely dense stellar association containing several Wolf-Rayet and
O-type stars, at least four of which show a common velocity. Only half an
arcsecond north from IRS 13E there is a complex of extremely red sources,
so-called IRS 13N. Their nature is still unclear. Based on the analysis of
their colors, there are two main possibilities: (1) dust embedded sources older
than few Myr, or (2) extremely young objects with ages less than 1Myr.
  Aims: We present the first proper motion measurements of IRS 13N members, and
additionally give proper motions of four of IRS 13E stars resolved in the
L'-band.
  Methods: The L'-band (3.8 micron) observations have been carried out using
the NACO adaptive optics system at the ESO VLT. Proper motions have been
obtained by linear fitting of the stellar positions extracted by StarFinder as
a function of time, weighted by positional uncertainties.
  Results: We show that six of seven resolved northern sources show a common
proper motion, thus revealing a new comoving group of stars in the central half
parsec of the Milky Way. The common proper motions of IRS 13E and IRS 13N
clusters are significantly (>5sigma) different. We also performed a fitting of
the positional data for those stars onto Keplerian orbits, assuming SgrA* as
the center of the orbit. Our results favor the very young stars hypothesis.


title: The Accelerated Recombination, and the ACBAR and WMAP data

abstract:
  We have investigated the deviation from the standard recombination process,
using the ACBAR 2008 and the WMAP 3 year data. In this investigation, we have
considered the possibility of the accelerated recombination as well as the
delayed recombination. We find that the accelerated recombination is as likely
as the delayed recombination, and there is some degeneracy between
$\epsilon_{\alpha}$ and \{$n_s$, $\log[10^{10}A_s]$, $H_0$\}.


title:
Discretization of transfer operators using a sparse hierarchical tensor
  basis - the Sparse Ulam method

abstract:
  The global macroscopic behaviour of a dynamical system is encoded in the
eigenfunctions of a certain transfer operator associated to it. For systems
with low dimensional long term dynamics, efficient techniques exist for a
numerical approximation of the most important eigenfunctions, cf. DeJu99a. They
are based on a projection of the operator onto a space of piecewise constant
functions supported on a neighborhood of the attractor - Ulam's method.
  In this paper we develop a numerical technique which makes Ulam's approach
applicable to systems with higher dimensional long term dynamics. It is based
on ideas for the treatment of higher dimensional partial differential equations
using sparse grids. We develop the technique, establish statements about its
complexity and convergence and present two numerical examples.


title: Moufang symmetry V. Triple closure

abstract:
  Triple closure of the infinitesimal translations of an analytic Moufang loop
is inquired. This property is equivalent to reductivity and relates Mal'tsev
algebras to the Lie triple systems.


title: Dynamic symmetry approach to entanglement

abstract:
  In this lectures I explain a connection between geometric invariant theory
and entanglement, and give a number of examples how this approach works.


title: Ferromagnetic to spin glass cross over in (La,Tb)_{2/3}Ca_{1/3}MnO_{3}

abstract:
  In the series La_{2/3-x}Tb_{x}Ca_{1/3}MnO_{3}, it is known that the
compositions are ferromagnetic for smaller values of x and show spin glass
characteristics at larger values of x. Our studies on the magnetic properties
of various compositions in the La_{2/3-x}Tb_{x}Ca_{1/3}MnO_{3} series show that
the cross over from ferromagnetic to spin glass region takes place above x ~
1/8. Also, a low temperature anomaly at 30 K, observed in the ac susceptibility
curves, disappears for compositions above this critical value of x. A mixed
phase region coexists in the narrow compositional range 0.1 <= x <= 0.125,
indicating that the ferromagnetic to spin glass cross over is not abrupt.


title: Brain architecture: A design for natural computation

abstract:
  Fifty years ago, John von Neumann compared the architecture of the brain with
that of computers that he invented and which is still in use today. In those
days, the organisation of computers was based on concepts of brain
organisation. Here, we give an update on current results on the global
organisation of neural systems. For neural systems, we outline how the spatial
and topological architecture of neuronal and cortical networks facilitates
robustness against failures, fast processing, and balanced network activation.
Finally, we discuss mechanisms of self-organization for such architectures.
After all, the organization of the brain might again inspire computer
architecture.


title: A supersymmetric Sawada-Kotera equation

abstract:
  A new supersymmetric equation is proposed for the Sawada-Kotera equation. The
integrability of this equation is shown by the existence of Lax representation
and infinite conserved quantities and a recursion operator.


title: Ekedahl-Oort strata in the supersingular locus

abstract:
  We give a description of the individual Ekedahl-Oort strata contained in the
supersingular locus in terms of Deligne-Lusztig varieties, refining a result of
Harashita.


title:
Bayesian considerations on the multiverse explanation of cosmic
  fine-tuning

abstract:
  The fundamental laws and constants of our universe seem to be finely tuned
for life. The various multiverse hypotheses are popular explanations for the
fine tuning. This paper reviews the four main suggestions on inference in the
presence of possible multiple universes and observer selection effects. Basic
identities from probability theory and previously unnoticed conditional
dependencies of the propositions involved are used to decide among the
alternatives. In the case of cosmic fine-tuning, information about the
observation is not independent of the hypothesis. It follows that the
observation should be used as data when comparing hypotheses. Hence, approaches
that use the observation only as background information are incorrect. It is
also shown that in some cases the self-sampling assumption by Bostrom leads to
probabilities greater than one, leaving the approach inconsistent. The "some
universe" (SU) approach is found wanting. Several reasons are given on why the
"this universe" (TU) approach seems to be correct. Lastly, the converse
selection effect by White is clarified by showing formally that the converse
condition leads to SU and its absence to TU. The overall result is that,
because multiverse hypotheses do not predict the fine-tuning for this universe
any better than a single universe hypothesis, the multiverse hypotheses fail as
explanations for cosmic fine-tuning. Conversely, the fine-tuning data does not
support the multiverse hypotheses.


title: Phase-coherent transport in InN nanowires of various sizes

abstract:
  We investigate phase-coherent transport in InN nanowires of various diameters
and lengths. The nanowires were grown by means of plasma-assisted molecular
beam epitaxy. Information on the phase-coherent transport is gained by
analyzing the characteristic fluctuation pattern in the magneto-conductance.
For a magnetic field oriented parallel to the wire axis we found that the
correlation field mainly depends on the wire cross section, while the
fluctuation amplitude is governed by the wire length. In contrast, if the
magnetic field is oriented perpendicularly, for wires longer than approximately
200 nm the correlation field is limited by the phase coherence length. Further
insight into the orientation dependence of the correlation field is gained by
measuring the conductance fluctuations at various tilt angles of the magnetic
field.


title:
Muon Anomalous Magnetic Moment and Lepton Flavor Violating Tau Decay in
  Unparticle Physics

abstract:
  We study effects of unparticle physics on muon g-2 and LFV tau decay
processes. LFV interactions between the Standard Model sector and unparticles
can explain the difference of experimental value of muon g-2 from the Standard
Model prediction. While the same couplings generate LFV tau decay, we found
that LFV coupling can be of O(0.1 ... 1) without conflict with experimental
bounds of LFV tau decay if the scaling dimension of unparticle operator d_{U} >
1.6.


title:
Rational points in periodic analytic sets and the Manin-Mumford
  conjecture

abstract:
  We present a new proof of the Manin-Mumford conjecture about torsion points
on algebraic subvarieties of abelian varieties. Our principle, which admits
other applications, is to view torsion points as rational points on a complex
torus and then compare (i) upper bounds for the number of rational points on a
transcendental analytic variety (Bombieri-Pila-Wilkie) and (ii) lower bounds
for the degree of a torsion point (Masser), after taking conjugates. In order
to be able to deal with (i), we discuss (Thm. 2.1) the semi-algebraic curves
contained in an analytic variety supposed invariant for translations by a full
lattice, which is a topic with some independent motivation.


title:
Jacobians among Abelian threefolds: a formula of Klein and a question of
  Serre

abstract:
  Let k be a field and f be a Siegel modular form of weight h \geq 0 and genus
g>1 over k. Using f, we define an invariant of the k-isomorphism class of a
principally polarized abelian variety (A,a)/k of dimension g. Moreover when
(A,a) is the Jacobian of a smooth plane curve, we show how to associate to f a
classical plane invariant. As straightforward consequences of these
constructions, when g=3 and k is a subfield of the complex field, we obtain (i)
a new proof of a formula of Klein linking the modular form \chi_{18} to the
square of the discriminant of plane quartics ; (ii) a proof that one can decide
when (A,a) is a Jacobian over k by looking whether the value of \chi_{18} at
(A,a) is a square in k. This answers a question of J.-P. Serre. Finally, we
study the possible generalizations of this approach for g>3.


title: Algebraic Pattern Matching in Join Calculus

abstract:
  We propose an extension of the join calculus with pattern matching on
algebraic data types. Our initial motivation is twofold: to provide an
intuitive semantics of the interaction between concurrency and pattern
matching; to define a practical compilation scheme from extended join
definitions into ordinary ones plus ML pattern matching. To assess the
correctness of our compilation scheme, we develop a theory of the applied join
calculus, a calculus with value passing and value matching. We implement this
calculus as an extension of the current JoCaml system.


title: Graphene Antidot Lattices - Designed Defects and Spin Qubits

abstract:
  Antidot lattices, defined on a two-dimensional electron gas at a
semiconductor heterostructure, are a well-studied class of man-made structures
with intriguing physical properties. We point out that a closely related
system, graphene sheets with regularly spaced holes ("antidots"), should
display similar phenomenology, but within a much more favorable energy scale, a
consequence of the Dirac fermion nature of the states around the Fermi level.
Further, by leaving out some of the holes one can create defect states, or
pairs of coupled defect states, which can function as hosts for electron spin
qubits. We present a detailed study of the energetics of periodic graphene
antidot lattices, analyze the level structure of a single defect, calculate the
exchange coupling between a pair of spin qubits, and identify possible avenues
for further developments.


title: The needlets bispectrum

abstract:
  The purpose of this paper is to join two different threads of the recent
literature on random fields on the sphere, namely the statistical analysis of
higher order angular power spectra on one hand, and the construction of
second-generation wavelets on the sphere on the other. To this aim, we
introduce the needlets bispectrum and we derive a number of convergence
results. Here, the limit theory is developed in the high resolution sense. The
leading motivation of these results is the need for statistical procedures for
searching non-Gaussianity in Cosmic Microwave Background radiation.


title:
Discovery of VHE gamma-rays from the high-frequency-peaked BL Lac object
  RGB J0152+017

abstract:
  Aims: The BL Lac object RGB J0152+017 (z=0.080) was predicted to be a very
high-energy (VHE; > 100 GeV) gamma-ray source, due to its high X-ray and radio
fluxes. Our aim is to understand the radiative processes by investigating the
observed emission and its production mechanism using the High Energy
Stereoscopic System (H.E.S.S.) experiment. Methods: We report recent
observations of the BL Lac source RGB J0152+017 made in late October and
November 2007 with the H.E.S.S. array consisting of four imaging atmospheric
Cherenkov telescopes. Contemporaneous observations were made in X-rays by the
Swift and RXTE satellites, in the optical band with the ATOM telescope, and in
the radio band with the Nancay Radio Telescope. Results: A signal of 173
gamma-ray photons corresponding to a statistical significance of 6.6 sigma was
found in the data. The energy spectrum of the source can be described by a
powerlaw with a spectral index of 2.95+/-0.36stat+/-0.20syst. The integral flux
above 300 GeV corresponds to ~2% of the flux of the Crab nebula. The source
spectral energy distribution (SED) can be described using a two-component
non-thermal synchrotron self-Compton (SSC) leptonic model, except in the
optical band, which is dominated by a thermal host galaxy component. The
parameters that are found are very close to those found in similar SSC studies
in TeV blazars. Conclusions: RGB J0152+017 is discovered as a source of VHE
gamma-rays by H.E.S.S. The location of its synchrotron peak, as derived from
the SED in Swift data, allows clearly classification it as a
high-frequency-peaked BL Lac (HBL).


title: In-medium QCD and Cherenkov gluons

abstract:
  The equations of in-medium gluodynamics are proposed. Their classical lowest
order solution is explicitly shown for a color charge moving with constant
speed. For nuclear permittivity larger than 1 it describes emission of
Cherenkov gluons resembling results of classical electrodynamics. The choice of
nuclear permittivity and Lorentz-invariance of the problem are discussed.
Effects induced by the transversely and longitudinally moving (relative to the
collision axis) partons at LHC energies are described.


title: Accelerator design concept for future neutrino facilities

abstract:
  This document summarizes the findings of the Accelerator Working Group (AWG)
of the International Scoping Study (ISS) of a Future Neutrino Factory and
super-beam Facility. The work of the group took place at three plenary meetings
along with three workshops, and an oral summary report was presented at the
NuFact06 workshop held at UC-Irvine in August, 2006. The goal was to reach
consensus on a baseline design for a Neutrino Factory complex. One aspect of
this endeavor was to examine critically the advantages and disadvantages of the
various Neutrino Factory schemes that have been proposed in recent years.


title: The rotating wind of the quasar PG 1700+518

abstract:
  It is now widely accepted that most galaxies undergo an active phase, during
which a central super-massive black hole generates vast radiant luminosities
through the gravitational accretion of gas. Winds launched from a rotating
accretion disk surrounding the black hole are thought to play a critical role,
allowing the disk to shed angular momentum that would otherwise inhibit
accretion. Such winds are capable of depositing large amounts of mechanical
energy in the host galaxy and its environs, profoundly affecting its formation
and evolution, and perhaps regulating the formation of large-scale cosmological
structures in the early Universe. Although there are good theoretical grounds
for believing that outflows from active galactic nuclei originate as disk
winds, observational verification has proven elusive. Here we show that
structures observed in polarized light across the broad H-alpha emission line
in the quasar PG 1700+158 originate close to the accretion disk in an electron
scattering wind. The wind has large rotational motions (~4,000 km/s), providing
direct observational evidence that outflows from active galactic nuclei are
launched from the disks. Moreover, the wind rises nearly vertically from the
disk, favouring launch mechanisms that impart an initial acceleration
perpendicular to the disk plane.


title: Regular and chaotic motion in elliptical galaxies

abstract:
  Here I review recent work, by other authors and by myself, on some particular
topics related to the regular and chaotic motion in elliptical galaxies. I show
that it is quite possible to build highly stable triaxial stellar systems that
include large fractions of chaotic orbits and that partially and fully chaotic
orbits fill different regions of space, so that it is important not to group
them together under the single denomination of chaotic orbits. Partially
chaotic orbits should not be confused with weakly fully chaotic orbits either,
and their spatial distributions are also different. Slow figure rotation (i.e.,
rotation in systems with zero angular momentum) seems to be always present in
highly flattened models that result from cold collapses, with the rotational
velocity diminishing or becoming negligibly small for less flattened models.
Finally, I comment on the usefulness and limitation of the classification of
regular orbits via frequency analysis.


title:
On the origin of clustering of frequency ratios in the atoll source 4U
  1636-53

abstract:
  A long discussion has been devoted to the issue of clustering of the kHz QPO
frequency ratios in the neutron star sources. While the distribution of ratios
inferred from an occurrence of a single QPO seems to be consistent with a
random walk, the distribution based on simultaneous detections of both peaks
indicates a preference of ratios of small integers. Based on the public RXTE
data we further investigate this issue for the source 4U 1636-53. Quality
factors and rms amplitudes of both the QPOs nearly equal to the points where
the frequencies are commensurable, and where the twin QPO detections cluster.
We discuss a connection of the clustering with the varying properties of the
two QPO modes. Assuming approximative relations for the observed correlations
of the QPO properties, we attempt to reproduce the frequency and ratio
distributions using a simple model of a random-walk evolution along the
observed frequency-frequency correlation. We obtain results which are in
qualitative agreement with the observed distributions.


title: Elliptic curves with all quadratic twists of positive rank

abstract:
  We observe that there are elliptic curves over number fields all of whose
quadratic twists must have positive rank, assuming the Birch-Swinnerton-Dyer
conjecture. We give a classification of such curves in terms of their local
behaviour, and characterise them in terms of the Galois action on the Tate
module. In particular, their existence shows that Goldfeld's conjecture does
not extend directly to elliptic curves over number fields.


title:
W Pair Production at the LHC - I. Virtual O(alpha_s^2) Corrections in
  the High Energy Limit

abstract:
  We present the result for the two-loop and the one-loop squared virtual QCD
corrections to the W boson pair production in the quark-anti-quark-annihilation
channel in the limit where all kinematical invariants are large compared to the
mass of the W boson. The infrared pole structure is in agreement with the
prediction of Catani's general formalism for the singularities of two loop
amplitudes.


title: The Nuclear Physics of Neutron Stars

abstract:
  A remarkable fact about spherically-symmetric neutron stars in hydrostatic
equilibrium - the so-called Schwarzschild stars - is that the only physics that
they are sensitive to is the equation of state of neutron-rich matter. As such,
neutron stars provide a myriad of observables that may be used to constrain
poorly known aspects of the nuclear interaction under extreme conditions of
density. After discussing many of the fascinating phases encountered in neutron
stars, I will address how powerful theoretical, experimental, and observational
constraints may be used to place stringent limits on the equation of state of
neutron-rich matter.


title:
Global classical solutions of the Vlasov-Darwin system for small initial
  data

abstract:
  A global-in-time existence theorem for classical solutions of the
Vlasow-Darwin system is given under the assumption of smallness of the initial
data. Furthermore it is shown that in case of spherical symmetry the system
degenerates to the relativistic Vlasov-Poisson system.


title:
Multiplicative cross-correlated noise induced escape rate from a
  metastable state

abstract:
  We present an analytical framework to study the escape rate from a metastable
state under the influence of two external multiplicative cross-correlated noise
processes. Starting from a phenomenological stationary Langevin description
with multiplicative noise processes, we have investigated the Kramers' theory
for activated rate processes in a nonequilibrium open system (one-dimensional
in nature) driven by two external cross-correlated noise processes which are
Gaussian, stationary and delta correlated. Based on the Fokker-Planck
description in phase space, we then derive the escape rate from a metastable
state in the moderate to large friction limit to study the effect of degree of
correlation on the same. By employing numerical simulation in the presence of
external cross-correlated additive and multiplicative noises we check the
validity of our analytical formalism for constant dissipation, which shows a
satisfactory agreement between both the approaches for the specific choice of
noise processes. It is evident both from analytical development and the
corresponding numerical simulation that the enhancement of rate is possible by
increasing the degree of correlation of the external fluctuations.

categories: cond-mat.soft cond-mat.other cond-mat.stat-mech physics.chem-ph


title: Global action-angle variables for the periodic Toda lattice

abstract:
  In this paper we construct global action-angle variables for the periodic
Toda lattice.


title: Noncommutative variations on Laplace's equation

abstract:
  As a first step at developing a theory of noncommutative nonlinear elliptic
partial differential equations, we analyze noncommutative analogues of
Laplace's equation and its variants (some of the them nonlinear) over
noncommutative tori. Along the way we prove noncommutative analogues of many
results in classical analysis, such as Wiener's Theorem on functions with
absolutely convergent Fourier series, and standard existence and non-existence
theorems on elliptic functions. We show that many many classical methods,
including the Maximum Principle, the direct method of the calculus of
variations, the use of the Leray-Schauder Theorem, etc., have analogues in the
noncommutative setting.


title:
Using Animated Textures to Visualize Electromagnetic Fields and Energy
  Flow

abstract:
  Animated textures can be used to visualize the spatial structure and temporal
evolution of vector fields at high spatial resolution. The animation requires
two time-dependent vector fields. The first of these vector fields determines
the spatial structure to be displayed. The second is a velocity field that
determines the time evolution of the field lines of the first vector field. We
illustrate this method with an example in magneto-quasi-statics, where the
second velocity field is taken to be the ExB drift velocity of electric
monopoles. This technique for displaying time-dependent electromagnetic fields
has three pedagogical advantages: (1) the continuous nature of the
representation underscores the action-by-contact nature of forces transmitted
by fields; (2) the animated texture motion shows the direction of
electromagnetic energy flow; and (3) the time-evolving field configuration
enables insights into Maxwell stresses.


title:
Search for CP Violation in Neutral D Meson Cabibbo-suppressed Three-body
  Decays

abstract:
  Using 385 fb^-1 of e^+e^- collision data collected at center-of-mass energies
around 10.6 GeV, we search for time-integrated CP violation in the singly
Cabibbo-suppressed decays D0/D0bar --> pi^- pi^+ pi^0 and D0/D0bar --> K^- K^+
pi^0. Our model-independent and model-dependent analyses show no evidence of CP
violation in these decays. The intermediate amplitudes include well-defined
flavor states [e.g., rho(770)^+- pi^-+, K*(892)^+- K^-+] and CP-odd eigenstates
[e.g., rho(770)^0 pi^0, phi(1020) pi^0]. With the null results of the previous
analyses for CP-even eigenstates D0/D0bar --> K^+ K^- and D0/D0bar --> pi^+
pi^-, we conclude that any CP violation in the singly Cabibbo-suppressed charm
decays occurs at a rate which is not larger than a few percent. These results
are in accord with the Standard Model predictions, and provide constraints on
some models beyond the Standard Model.


title: Smectic-C tilt under shear in Smectic-A elastomers

abstract:
  Stenull and Lubensky [Phys. Rev. E {\bf 76}, 011706 (2007)] have argued that
shear strain and tilt of the director relative to the layer normal are coupled
in smectic elastomers and that the imposition of one necessarily leads to the
development of the other. This means, in particular, that a Smectic-A elastomer
subjected to a simple shear will develop Smectic-C-like tilt of the director.
Recently, Kramer and Finkelmann [arXiv:0708.2024, Phys. Rev. E {\bf 78}, 021704
(2008)] performed shear experiments on Smectic-A elastomers using two different
shear geometries. One of the experiments, which implements simple shear,
produces clear evidence for the development of Smectic-C-like tilt. Here, we
generalize a model for smectic elastomers introduced by Adams and Warner [Phys.
Rev. E {\bf 71}, 021708 (2005)] and use it to study the magnitude of
Smectic-C-like tilt under shear for the two geometries investigated by Kramer
and Finkelmann. Using reasonable estimates of model parameters, we estimate the
tilt angle for both geometries, and we compare our estimates to the
experimental results. The other shear geometry is problematic since it
introduces additional in-plane compressions in a sheet-like sample, thus
inducing instabilities that we discuss.


title:
Molecular Dynamics Simulations of Temperature Equilibration in Dense
  Hydrogen

abstract:
  The temperature equilibration rate in dense hydrogen (for both T_{i}>T_{e}
and T_i<T_e) has been calculated with molecular dynamics simulations for
temperatures between 10 and 600 eV and densities between 10^{20}/cc to
10^{24}/cc. Careful attention has been devoted to convergence of the
simulations, including the role of semiclassical potentials. We find that for
Coulomb logarithms L>1, a model by Gericke-Murillo-Schlanges (GMS) [Gericke et
al., PRE 65, 036418 (2002)] based on a T-matrix method and the approach by
Brown-Preston-Singleton [Brown et al., Phys. Rep. 410, 237 (2005)] agrees with
the simulation data to within the error bars of the simulation. For smaller
Coulomb logarithms, the GMS model is consistent with the simulation results.
Landau-Spitzer models are consistent with the simulation data for L>4.


title: Hydrogen atom in Palatini theories of gravity

abstract:
  We study the effects that the gravitational interaction of $f(R)$ theories of
gravity in Palatini formalism has on the stationary states of the Hydrogen
atom. We show that the role of gravity in this system is very important for
lagrangians $f(R)$ with terms that grow at low curvatures, which have been
proposed to explain the accelerated expansion rate of the universe. We find
that new gravitationally induced terms in the atomic Hamiltonian generate a
strong backreaction that is incompatible with the very existence of bound
states. In fact, in the 1/R model, Hydrogen disintegrates in less than two
hours. The universe that we observe is, therefore, incompatible with that kind
of gravitational interaction. Lagrangians with high curvature corrections do
not lead to such instabilities.


title: Theoretical tools for atom laser beam propagation

abstract:
  We present a theoretical model for the propagation of non self-interacting
atom laser beams. We start from a general propagation integral equation, and we
use the same approximations as in photon optics to derive tools to calculate
the atom laser beam propagation. We discuss the approximations that allow to
reduce the general equation whether to a Fresnel-Kirchhoff integral calculated
by using the stationary phase method, or to the eikonal. Within the paraxial
approximation, we also introduce the ABCD matrices formalism and the beam
quality factor. As an example, we apply these tools to analyse the recent
experiment by Riou et al. [Phys. Rev. Lett. 96, 070404 (2006)].


title: Analysis of the Karmarkar-Karp Differencing Algorithm

abstract:
  The Karmarkar-Karp differencing algorithm is the best known polynomial time
heuristic for the number partitioning problem, fundamental in both theoretical
computer science and statistical physics. We analyze the performance of the
differencing algorithm on random instances by mapping it to a nonlinear rate
equation. Our analysis reveals strong finite size effects that explain why the
precise asymptotics of the differencing solution is hard to establish by
simulations. The asymptotic series emerging from the rate equation satisfies
all known bounds on the Karmarkar-Karp algorithm and projects a scaling
$n^{-c\ln n}$, where $c=1/(2\ln2)=0.7213...$. Our calculations reveal subtle
relations between the algorithm and Fibonacci-like sequences, and we establish
an explicit identity to that effect.


title:
On Casson-type instanton moduli spaces over negative definite
  four-manifolds

abstract:
  Recently Andrei Teleman considered instanton moduli spaces over negative
definite four-manifolds $X$ with $b_2(X) \geq 1$. If $b_2(X)$ is divisible by
four and $b_1(X) =1$ a gauge-theoretic invariant can be defined; it is a count
of flat connections modulo the gauge group. Our first result shows that if such
a moduli space is non-empty and the manifold admits a connected sum
decomposition $X \cong X_1 # X_2$ then both $b_2(X_1)$ and $b_2(X_2)$ are
divisible by four; this rules out a previously natural appearing source of
4-manifolds with non-empty moduli space. We give in some detail a construction
of negative definite 4-manifolds which we expect will eventually provide
examples of manifolds with non-empty moduli space.


title: Josephson junction detector of non-Gaussian noise

abstract:
  The measurement of higher order cumulants of the current noise generated by a
nonlinear mesoscopic conductor using a Josephson junction as on-chip detector
is investigated theoretically. The paper addresses the regime where the noise
of the mesoscopic conductor initiates activated escape of the Josephson
detector out of the zero-voltage state, which can be observed as a voltage
rise. It is shown that the deviations from Johnson-Nyquist noise can mostly be
accounted for by an effective temperature which depends on the second noise
cumulant of the conductor. The deviations from Gaussian statistics lead to
rather weak effects and essentially only the third cumulant can be measured
exploiting the dependence of the corrections to the rate of escape from the
zero-voltage state on the direction of the bias current. These corrections
vanish as the bias current approaches the critical current. The theory is based
on a description of irreversible processes and fluctuations in terms of state
variables and conjugate forces. This approach, going back to work by Onsager
and Machlup, is extended to account for non-Gaussian noise, and it is shown
that the thermodynamically conjugate force to the electric charge plays a role
similar to the counting field introduced in more recent approaches to describe
non-Gaussian noise statistics. The theory allows to obtain asymptotically exact
results for the rate of escape in the weak noise limit for all values of the
damping strength of the Josephson detector. Also the feedback of the detector
on the noise generating conductor is fully taken into account by treating both
coupled mesoscopic devices on an equal footing.


title: Current log-periodic view on future world market development

abstract:
  Applicability of the concept of financial log-periodicity is discussed and
encouragingly verified for various phases of the world stock markets
development in the period 2000-2010. In particular, a speculative forecasting
scenario designed in the end of 2004, that properly predicted the world stock
market increases in 2007, is updated by setting some more precise constraints
on the time of duration of the present long-term equity market bullish phase. A
termination of this phase is evaluated to occur in around November 2009. In
particular, on the way towards this dead-line, a Spring-Summer 2008 increase is
expected. On the precious metals market a forthcoming critical time signal is
detected at the turn of March/April 2008 which marks a tendency for at least a
serious correction to begin.
  In the present extended version some predictions for the future oil price are
incorporated. In particular a serious correction on this market is expected to
start in the coming days.


title: Gravitational Lens Systems to probe Extragalactic Magnetic Fields

abstract:
  The Faraday rotation measurements of multiply-imaged gravitational lens
systems can be effectively used to probe the existence of large-scale ordered
magnetic fields in lensing galaxies and galaxy clusters. The available sample
of lens systems appears to suggest the presence of a coherent large-scale
magnetic field in giant elliptical galaxies somewhat similar to the spiral
galaxies.


title:
Observability and Detectability of Linear Switching Systems: A
  Structural Approach

abstract:
  We define observability and detectability for linear switching systems as the
possibility of reconstructing and respectively of asymptotically reconstructing
the hybrid state of the system from the knowledge of the output for a suitable
choice of the control input. We derive a necessary and sufficient condition for
observability that can be verified computationally. A characterization of
control inputs ensuring observability of switching systems is given. Moreover,
we prove that checking detectability of a linear switching system is equivalent
to checking asymptotic stability of a suitable switching system with guards
extracted from it, thus providing interesting links to Kalman decomposition and
the theory of stability of hybrid systems.


title: Phase diagram of a solution undergoing inverse melting

abstract:
  The phase diagram of $\alpha$-cyclodextrin/water/4-methylpyridine solutions,
a system undergoing inverse melting, has been studied by differential scanning
calorimetry, rheological methods, and X-rays diffraction. Two different fluid
phases separated by a solid region have been observed in the high
$\alpha$-cyclodextrin concentration range ($c$$\geq$150 mg/ml). Decreasing $c$,
the temperature interval where the solid phase exists decreases and eventually
disappears, and a first order phase transition is observed between the two
different fluid phases.


title: Introductory lectures on the Effective One Body formalism

abstract:
  The Effective One Body (EOB) formalism is an analytical approach which aims
at providing an accurate description of the motion and radiation of coalescing
binary black holes. We present a brief review of the basic elements of this
approach.


title: Co-Accretion of Chondrules and Dust in the Solar Nebula

abstract:
  We present a mechanism for chondrules to stick together by means of
compaction of a porous dust rim they sweep up as they move through the dusty
nebula gas. It is shown that dust aggregates formed out of micron-sized grains
stick to chondrules, forming a porous dust rim. When chondrules collide, this
dust can be compacted by means of rolling motions within the porous dust layer.
This mechanism dissipates the collisional energy, compacting the rim and
allowing chondrules to stick. The structure of the obtained chondrule-dust
agglomerates (referred to as compounds) then consists of three phases:
chondrules, porous dust, and dust that has been compacted by collisions.
Subsequently, these compounds accrete their own dust and collide with other
compounds. The evolution of the compound size distribution and the relative
importance of the phases is calculated by a Monte Carlo code. Growth ends, and
a simulation is terminated when all the dust in the compounds has been
compacted. Numerous runs are performed, reflecting the uncertainty in the
physical conditions at the chondrule formation time. It is found that compounds
can grow by 1-2 orders of magnitudes in radius, upto dm-sizes when turbulence
levels are low. However, relative velocities associated with radial drift form
a barrier for further growth. Earlier findings that the dust sweep-up by
chondrules is proportional to their sizes are confirmed. We contrast two
scenarios regarding how this dust evolved further towards the densely packed
rims seen in chondrites.


title: Virtual bilepton effects in polarized Moller scattering

abstract:
  We investigate the indirect effects of heavy vector bileptons being exchanged
in polarized Moller scattering, at the next generation of linear colliders.
Considering both longitudinal and transverse beam polarization, and accounting
for initial-state radiation, beamstrahlung and beam energy spread, we discuss
how angular distributions and asymmetries can be used to detect clear signals
of virtual bileptons, and the possibility of distinguishing theoretical models
that incorporate these exotic particles. We then estimate 95% C.L. bounds on
the mass of these vector bileptons and on their couplings to electrons.


title: The quantization of the B=1 and B=2 Skyrmions

abstract:
  We propose to set the Skyrme parameters F_{\pi} and e such that they
reproduce the physical masses of the nucleon and the deuteron. We allow
deformation using an axially symmetric solution and simulated annealing to
minimize the total energy for the B=1 nucleon and B=$ deuteron. First we find
that axial deformations are responsible for a significant reduction (factor of
\approx 4) of the rotational energy but also that it is not possible to get a
common set of parameters F_{\pi} and e which would fit both nucleon and
deuteron masses simultaneously at least for m_{\pi}= 138 MeV, 345 MeV and 500
MeV. This suggests that either m_{\pi}>500 MeV or additional terms must be
added to the Skyrme Lagrangian.


title: Epsilon-measures of entanglement

abstract:
  We associate to every entanglement measure a family of measures which depend
on a precision parameter, and which we call epsilon-measures of entanglement.
Their definition aims at addressing a realistic scenario in which we need to
estimate the amount of entanglement in a state that is only partially known. We
show that many properties of the original measure are inherited by the family,
in particular weak monotonicity under transformations applied by means of Local
Operations and Classical Communication (LOCC). On the other hand, they may
increase on average under stochastic LOCC. Remarkably, the epsilon-version of a
convex entanglement measure is continuous even if the original entanglement
measure is not, so that the epsilon-version of an entanglement measure may be
actually considered a smoothed version of it.


title: Improved measurement of CP observables in B- --> D0_{CP} K- decays

abstract:
  We present a study of the decay B- -> D0_CP K- and its charge conjugate,
where D0_CP is reconstructed in both a non-CP flavor eigenstate and in CP
(CP-even and CP-odd) eigenstates, based on a sample of 382 million Y(4S) ->
BBbar decays collected with the BABAR detector at the PEP-II e+e- storage ring.
We measure the direct CP asymmetries A_CP\pm and the ratios of the branching
fractions R_CP\pm: A_CP+ = 0.27\pm 0.09(stat)\pm 0.04(syst), A_CP- =-0.09\pm
0.09(stat)\pm 0.02(syst), R_CP+ = 1.06\pm 0.10(stat)\pm 0.05(syst), R_CP- =
1.03\pm 0.10(stat)\pm 0.05(syst). We also express the results in terms of the
so called Cartesian coordinates x+, x-, and r^2: x+ = -0.09\pm 0.05(stat)\pm
0.02(syst)}, x- = 0.10\pm 0.05(stat)\pm 0.03(syst)}, r^2 = 0.05\pm
0.07(stat)\pm 0.03(syst)}. These results will help to better constrain the
phase parameter $\gamma=\arg(-V_{ud}V_{ub}^*/V_{cd}V_{cb}^*)$ of the
Cabibbo-Kobayashi-Maskawa quark mixing matrix.


title:
Reconciling Semiclassical and Bohmian Mechanics: III. Scattering states
  for continuous potentials

abstract:
  In a previous paper [J. Chem. Phys. 121 4501 (2004)] a unique bipolar
decomposition, Psi = Psi1 + Psi2 was presented for stationary bound states Psi
of the one-dimensional Schroedinger equation, such that the components Psi1 and
Psi2 approach their semiclassical WKB analogs in the large action limit. The
corresponding bipolar quantum trajectories, as defined in the usual Bohmian
mechanical formulation, are classical-like and well-behaved, even when Psi has
many nodes, or is wildly oscillatory. A modification for discontinuous
potential stationary stattering states was presented in a second paper [J.
Chem. Phys. 124 034115 (2006)], whose generalization for continuous potentials
is given here. The result is an exact quantum scattering methodology using
classical trajectories. For additional convenience in handling the tunneling
case, a constant velocity trajectory version is also developed.


title: A Nonlinear Model for Relativistic Electrons at Positive Temperature

abstract:
  We study the relativistic electron-positron field at positive temperature in
the Hartree-Fock-approximation. We consider both the case with and without
exchange term, and investigate the existence and properties of minimizers. Our
approach is non-perturbative in the sense that the relevant electron subspace
is determined in a self-consistent way. The present work is an extension of
previous work by Hainzl, Lewin, S\'er\'e, and Solovej where the case of zero
temperature was considered.


title:
Bifurcations, order, and chaos in the Bose-Einstein condensation of
  dipolar gases

abstract:
  We apply a variational technique to solve the time-dependent Gross-Pitaevskii
equation for Bose-Einstein condensates in which an additional dipole-dipole
interaction between the atoms is present with the goal of modelling the
dynamics of such condensates. We show that universal stability thresholds for
the collapse of the condensates correspond to bifurcation points where always
two stationary solutions of the Gross-Pitaevskii equation disappear in a
tangent bifurcation, one dynamically stable and the other unstable. We point
out that the thresholds also correspond to "exceptional points," i.e. branching
singularities of the Hamiltonian. We analyse the dynamics of excited condensate
wave functions via Poincare surfaces of section for the condensate parameters
and find both regular and chaotic motion, corresponding to (quasi-)
periodically oscillating and irregularly fluctuating condensates, respectively.
Stable islands are found to persist up to energies well above the saddle point
of the mean-field energy, alongside with collapsing modes. The results are
applicable when the shape of the condensate is axisymmetric.


title: Dominant Contribution in Pion Production Single-Spin Asymmetries

abstract:
  Working with a completely collinear twist-3 factorized cross-section formula,
we identify two largely dominant partonic sub-processes, which contribute to
the single-spin asymmetries in semi-inclusive pion production, in the region of
large pT and medium-large xF.


title: A Qualitative Modal Representation of Quantum Register Transformations

abstract:
  We introduce two modal natural deduction systems that are suitable to
represent and reason about transformations of quantum registers in an abstract,
qualitative, way. Quantum registers represent quantum systems, and can be
viewed as the structure of quantum data for quantum operations. Our systems
provide a modal framework for reasoning about operations on quantum registers
(unitary transformations and measurements), in terms of possible worlds (as
abstractions of quantum registers) and accessibility relations between these
worlds. We give a Kripke--style semantics that formally describes quantum
register transformations and prove the soundness and completeness of our
systems with respect to this semantics.


title:
Graphene Synthesis via the High Pressure - High Temperature Growth
  Process

abstract:
  We report on a new method for graphene synthesis and assessment of the
properties of the resulting large-area graphene layers. Graphene was produced
by the high pressure - high temperature growth from the natural graphitic
source by utilizing the molten Fe-Ni catalysts for dissolution of carbon. The
resulting large-area graphene flakes were transferred to the silicon - silicon
oxide substrates for the spectroscopic micro-Raman and scanning electron
microscopy inspection. The analysis of the G peak, D, T+D and 2D bands in the
Raman spectra under the 488-nm laser excitation indicate that the high pressure
- high temperature technique is capable of producing the high-quality
large-area single-layer graphene with a low defect density. The proposed method
may lead to a more reliable graphene synthesis and facilitate its purification
and chemical doping.


title: Multi-wavelength observations of a nearby multi-phase interstellar cloud

abstract:
  High-resolution spectroscopic observations (UV HST/STIS and optical) are used
to characterize the physical state and velocity structure of the multiphase
interstellar medium seen towards the nearby (170 pc) star HD102065, located
behind the tail of a cometary-shaped, infrared cirrus-cloud, in the area of
interaction between the Sco-Cen OB association and the Local Bubble. We analyze
interstellar components present along the line of sight by fitting multiple
transitions from CO, CH, CH+, C I, S I, Fe I, Mg I, Mg II, Mn II, P II, Ni II,
C II, N I, O I, Si III, C IV, and Si IV. The absorption spectra are
complemented by H I, CO and C II emission-line spectra, H$_2$ column-densities
derived from FUSE spectra, and IRAS images. Gas components of a wide range of
temperatures and ionization states are detected along the line of sight. Most
of the hydrogen column-density is in cold, diffuse, molecular gas at low LSR
velocity. This gas is mixed with traces of warmer molecular gas traced by H2 in
the J>2 levels, in which the observed CH+ must be formed. We also identify
three distinct components of warm gas at negative velocities down to -20 km/s.
The temperature and gas excitation are shown to increase with increasing
velocity shift from the bulk of the gas. Hot gas at temperatures of several
10^5 K is detected in the most negative velocity component in the
highly-ionized species. This hot gas is also detected in very strong lines of
less-ionized species (Mg II, Si II* and C II*) for which the bulk of the gas is
cooler. We relate the observational results to evidence for dynamical impact of
the Sco-Cen stellar association on the nearby ISM. We propose a scenario where
the cirrus cloud has been hit a few 10^5 yr ago by a supernova blast wave
originating from the Lower Centaurus Crux group of the Sco-Cen association.


title:
Exit problem of a two-dimensional risk process from the quadrant: Exact
  and asymptotic results

abstract:
  Consider two insurance companies (or two branches of the same company) that
divide between them both claims and premia in some specified proportions. We
model the occurrence of claims according to a renewal process. One ruin problem
considered is that of the corresponding two-dimensional risk process first
leaving the positive quadrant; another is that of entering the negative
quadrant. When the claims arrive according to a Poisson process, we obtain a
closed form expression for the ultimate ruin probability. In the general case,
we analyze the asymptotics of the ruin probability when the initial reserves of
both companies tend to infinity under a Cram\'{e}r light-tail assumption on the
claim size distribution.


title: The Flattening of Globular Clusters

abstract:
  In the three nearest luminous galaxies, the Milky Way System, the Andromeda
Galaxy and NGC 5128 the brightest globular clusters are rounder than the
faintest ones. On the other hand (contrary to some previous results) the
flattening of individual LMC clusters is found to be independent of their
luminosities. This suggests the possibility that the relationship between the
flattening and luminosity of clusters might depend on host galaxy luminosity.
No significant differences are found between the intrinsic flattening
distributions of Galactic old halo, Galactic young halo and Galactic bulge/disk
clusters. Such a dependence might perhaps have been expected if tidal forces
(which are largest at small Galactocentric distances) removed angular momentum
from globular clusters. The preliminary conclusion by Norris that clusters with
blue horizontal branches are more flattened than red HB clusters is not
confirmed by the larger data base that is now available. In other words there
is no evidence for the puzzling claimed correlation between the flattening and
the horizontal branch morphology of Galactic globular clusters.


title: Critical currents in graphene Josephson junctions

abstract:
  We study the superconducting correlations induced in graphene when it is
placed between two superconductors, focusing in particular on the supercurrents
supported by the 2D system. For this purpose we make use of a formalism placing
the emphasis on the many-body aspects of the problem, with the aim of
investigating the dependence of the critical currents on relevant variables
like the distance L between the superconducting contacts, the temperature, and
the doping level. Thus we show that, despite the vanishing density of states at
the Fermi level in undoped graphene, supercurrents may exist at zero
temperature with a natural 1/L^3 dependence at large L. When temperature
effects are taken into account, the supercurrents are further suppressed beyond
the thermal length L_T (~ v_F / k_B T, in terms of the Fermi velocity v_F of
graphene), entering a regime where the decay is given by a 1/L^5 dependence. On
the other hand, the supercurrents can be enhanced upon doping, as the Fermi
level is shifted by a chemical potential \mu from the charge neutrality point.
This introduces a new crossover length L* ~ v_F / \mu, at which the effects of
the finite charge density start being felt, marking the transition from the
short-distance 1/L^3 behavior to a softer 1/L^2 decay of the supercurrents at
large L. It turns out that the decay of the critical currents is given in
general by a power-law behavior, which can be seen as a consequence of the
perfect scaling of the Dirac theory applied to the low-energy description of
graphene.


title: Entropy of nonlinear black holes in quadratic gravity

abstract:
  Employing the Noether charge technique and Visser's Euclidean approach the
entropy of the nonlinear black hole described by the perturbative solution of
the system of coupled equations of the quadratic gravity and nonlinear
electrodynamics is constructed. The solution is parametrized by the exact
location of the event horizon and charge. Special emphasis in put on the
extremal configuration. Consequences of the second choice of the boundary
conditions, in which the solution is paramerized by the charge and the total
mass as seen by a distant observer is briefly examined.


title: A theoretical approach for Pareto-Zipf law

abstract:
  We suggest an analytical approach for Pareto-Zipf law, where we assume random
multiplicative noise and fragmentation processes for the growth of the number
of citizens of each city and the number of the cities, respectively.


title:
Vacuum polarization of massive spinor and vector fields in the spacetime
  of a nonlinear black hole

abstract:
  Building on general formulas obtained from the approximate renormalized
effective action, the stress-energy tensor of the quantized massive spinor and
vector fields in the spacetime of the regular black hole is constructed. Such a
black hole is the solution to the coupled system of nonlinear electrodynamics
and general relativity. A detailed analytical and numerical analysis of the
stress-energy tensor in the exterior region is presented. It is shown that for
small values of the charge as well as large distances from the black hole the
leading behavior of the stress-energy tensor is similar to that in the
Reissner-Nordstr\"om geometry. Important differences appear when the inner
horizon becomes close to the event horizon. A special emphasis is put on the
extremal configuration and it is shown that the stress-energy tensor is regular
inside the event horizon of the extremal black hole.


title: Increasing thermoelectric efficiency towards the Carnot limit

abstract:
  We study the problem of thermoelectricity and propose a simple microscopic
mechanism for the increase of thermoelectric efficiency. We consider the cross
transport of particles and energy in open classical ergodic billiards. We show
that, in the linear response regime, where we find exact expressions for all
transport coefficients, the thermoelectric efficiency of ideal ergodic gases
can approach Carnot efficiency for sufficiently complex charge carrier
molecules. Our results are clearly demonstrated with a simple numerical
simulation of a Lorentz gas of particles with internal rotational degrees of
freedom.


title: A Categorical Formulation of Superalgebra and Supergeometry

abstract:
  We reformulate superalgebra and supergeometry in completely categorical terms
by a consequent use of the functor of points. The increased abstraction of this
approach is rewarded by a number of great advantages. First, we show that one
can extend supergeometry completely naturally to infinite-dimensional contexts.
Secondly, some subtle and sometimes obscure-seeming points of supergeometry
become clear in light of these results, e.g., the relation between the
Berezin-Leites-Kostant and the de Witt-Rogers approaches, and the precise
geometric meaning of odd parameters in supergeometry. In addition, this method
allows us to construct in an easy manner superspaces of morphisms between
superobjects, i.e., the inner Hom objects associated with the sets of such
morphisms. The results of our work rely heavily and were inspired by the ideas
of V. Molotkov, who first outlined the approach extensively expounded here.


title: Frobenius algebras and skein modules of surfaces in 3-manifolds

abstract:
  For each Frobenius algebra there is defined a skein module of surfaces
embedded in a given 3-manifold and bounding a prescribed curve system in the
boundary. The skein relations are local and generate the kernel of a certain
natural extension of the corresponding topological quantum field theory. In
particular the skein module of the 3-ball is isomorphic to the ground ring of
the Frobenius algebra. We prove a presentation theorem for the skein module
with generators incompressible surfaces colored by elements of a generating set
of the Frobenius algebra, and with relations determined by tubing geometry in
the manifold and relations of the algebra.


title:
Reconciling Semiclassical and Bohmian Mechanics: II. Scattering states
  for discontinuous potentials

abstract:
  In a previous paper [J. Chem. Phys. 121 4501 (2004)] a unique bipolar
decomposition, Psi = Psi1 + Psi2 was presented for stationary bound states Psi
of the one-dimensional Schroedinger equation, such that the components Psi1 and
Psi2 approach their semiclassical WKB analogs in the large action limit.
Moreover, by applying the Madelung-Bohm ansatz to the components rather than to
Psi itself, the resultant bipolar Bohmian mechanical formulation satisfies the
correspondence principle. As a result, the bipolar quantum trajectories are
classical-like and well-behaved, even when Psi has many nodes, or is wildly
oscillatory. In this paper, the previous decomposition scheme is modified in
order to achieve the same desirable properties for stationary scattering
states. Discontinuous potential systems are considered (hard wall, step, square
barrier/well), for which the bipolar quantum potential is found to be zero
everywhere, except at the discontinuities. This approach leads to an exact
numerical method for computing stationary scattering states of any desired
boundary conditions, and reflection and transmission probabilities. The
continuous potential case will be considered in a future publication.


title:
Distribution of kilohertz QPO frequencies and their ratios in the atoll
  source 4U 1636-53

abstract:
  A recently published study on long term evolution of the frequencies of the
kilohertz quasi-periodic oscillations (QPOs) in the atoll source 4U 1636-53
concluded that there is no preferred frequency ratio in a distribution of twin
QPOs that was inferred from the distribution of a single frequency alone.
However, we find that the distribution of the ratio of actually observed pairs
of kHz QPO frequencies is peaked close to the 3/2 value, and possibly also
close to the 5/4 ratio. To resolve the apparent contradiction between the two
studies, we examine in detail the frequency distributions of the lower kHz QPO
and the upper kHz QPO detected in our data set. We demonstrate that for each of
the two kHz QPOs (the lower or the upper), the frequency distribution in all
detections of a QPO differs from the distribution of frequency of the same QPO
in the subset of observations where both the kHz QPOs are detected. We conclude
that detections of individual QPOs alone should not be used for calculation of
the distribution of the frequency ratios.


title:
Constraints and Stability in Vector Theories with Spontaneous Lorentz
  Violation

abstract:
  Vector theories with spontaneous Lorentz violation, known as bumblebee
models, are examined in flat spacetime using a Hamiltonian constraint analysis.
In some of these models, Nambu-Goldstone modes appear with properties similar
to photons in electromagnetism. However, depending on the form of the theory,
additional modes and constraints can appear that have no counterparts in
electromagnetism. An examination of these constraints and additional degrees of
freedom, including their nonlinear effects, is made for a variety of models
with different kinetic and potential terms, and the results are compared with
electromagnetism. The Hamiltonian constraint analysis also permits an
investigation of the stability of these models. For certain bumblebee theories
with a timelike vector, suitable restrictions of the initial-value solutions
are identified that yield ghost-free models with a positive Hamiltonian. In
each case, the restricted phase space is found to match that of
electromagnetism in a nonlinear gauge.


title: Simulating the Quantum Magnet

abstract:
  To gain deeper insight into the dynamics of complex quantum systems we need a
quantum leap in computer simulations. We can not translate quantum behaviour
arising with superposition states or entanglement efficiently into the
classical language of conventional computers. The final solution to this
problem is a universal quantum computer [1], suggested in 1982 and envisioned
to become functional within the next decade(s); a shortcut was proposed via
simulating the quantum behaviour of interest in a different quantum system,
where all parameters and interactions can be controlled and the outcome
detected sufficiently well. Here we study the feasibility of a quantum
simulator based on trapped ions [2]. We experimentally simulate the adiabatic
evolution of the smallest non-trivial spin system from the paramagnetic into
the (anti-)ferromagnetic order with a quantum magnetisation for two spins of
98%, controlling and manipulating all relevant parameters of the Hamiltonian
independently via electromagnetic fields. We prove that the observed transition
is not driven by thermal fluctuations, but of quantum mechanical origin, the
source of quantum fluctuations in quantum phase transitions [3]. We observe a
final superposition state of the two degenerate spin configurations for the
ferromagnetic and the antiferromagnetic order, respectively. These correspond
to deterministically entangled states achieved with a fidelity up to 88%. Our
work demonstrates a building block for simulating quantum spin-Hamiltonians
with trapped ions. The method has potential for scaling to a higher number of
coupled spins [2].


title: Measurement of Coulomb drag between Anderson insulators

abstract:
  We report observations of the Coulomb drag effect between two effectively 2-d
insulating a-Si_{1-x}Nb_{x} films. We find that there only exist a limited
range of experimental parameters over which we can measure a sizable
linear-response transresistivity (\rho_{d}). The temperature dependence of
\rho_{d} is consistent with the layers being Efros-Shklovskii Anderson
insulators provided that a 3-d density of states and a localization length
smaller than that obtained from the DC layer-conductivity are assumed.


title: The non-commutative $A$-polynomial of twist knots

abstract:
  The purpose of the paper is two-fold: to introduce a multivariable creative
telescoping method, and to apply it in a problem of Quantum Topology: namely
the computation of the non-commutative $A$-polynomial of twist knots.
  Our multivariable creative telescoping method allows us to compute linear
recursions for sums of the form $J(n)=\sum_k c(n,k) \hatJ (k)$ given a
recursion relation for $(\hatJ(n))$ a the hypergeometric kernel $c(n,k)$. As an
application of our method, we explicitly compute the non-commutative
$A$-polynomial for twist knots with -8 and 11 crossings. The non-commutative
$A$-polynomial of a knot encodes the monic, linear, minimal order
$q$-difference equation satisfied by the sequence of colored Jones polynomials
of the knot. Its specialization to $q=1$ is conjectured to be the better-known
$A$-polynomial of a knot, which encodes important information about the
geometry and topology of the knot complement. Unlike the case of the Jones
polynomial, which is easily computable for knots with 50 crossings, the
$A$-polynomial is harder to compute and already unknown for some knots with 12
crossings.


title: Pollution of single white dwarfs by accretion of many small asteroids

abstract:
  Extrapolating from the solar system's asteroid belt, we propose that
externally-contaminated white dwarfs without an infrared excess may be
experiencing continuous accretion of gas-phase material that ultimately is
derived from the tidal destruction of multiple small asteroids. If this
scenario is correct, then observations of metal-polluted white dwarfs may lead
to determining the bulk elemental compositions of ensembles of extrasolar minor
planets.


title: Notes on Measure and Integration

abstract:
  This text grew out of notes I have used in teaching a one quarter course on
integration at the advanced undergraduate level. My intent is to introduce the
Lebesgue integral in a quick, and hopefully painless, way and then go on to
investigate the standard convergence theorems and a brief introduction to the
Hilbert space of $L^2$ functions on the interval.
  The actual construction of Lebesgue measure and proofs of its key properties
are relegated to an appendix. Instead the text introduces Lebesgue measure as a
generalization of the concept of length and motivates its key properties:
monotonicity, countable additivity, and translation invariance.


title:
Black hole state counting in Loop Quantum Gravity: A number theoretical
  approach

abstract:
  We give a practical method to exactly compute black hole entropy in the
framework of Loop Quantum Gravity. Along the way we provide a complete
characterization of the relevant sector of the spectrum of the area operator,
including degeneracies, and determine the number of solutions to the projection
constraint analytically. We use a computer implementation of the proposed
algorithm to confirm and extend previous results on the detailed structure of
the black hole degeneracy spectrum.


title:
Discovery of magnetic fields in the very young, massive stars W601 (NGC
  6611) and OI 201 (NGC 2244)

abstract:
  Context: Recent spectropolarimetric observations of Herbig Ae/Be stars have
yielded new arguments in favour of a fossil origin for the magnetic fields of
intermediate mass stars. Aims: To study the evolution of these magnetic fields,
and their impact on the evolution of the angular momentum of these stars during
the pre-main sequence phase, we observed Herbig Ae/Be members of young open
clusters of various ages. Methods: We obtained high-resolution
spectropolarimetric observations of Herbig Ae/Be stars belonging to the young
open clusters NGC 6611 (< 6 Myr), NGC 2244 (~1.9 Myr), and NGC 2264 (~8 Myr),
using ESPaDOnS at theCanada-France-Hawaii Telescope. Results: Here we report
the discovery of strong magnetic fields in two massive pre-main sequence
cluster stars. We detected, for the first time, a magnetic field in a pre-main
sequence rapid rotator: the 10.2 Msun Herbig B1.5e star W601 (NGC 6611; v sin i
~ 190 km/s). Our spectropolarimetric observations yield a longitudinal magnetic
field larger than 1 kG, and imply a rotational period shorter than 1.7 days.
The spectrum of this very young object (age ~ 0.017 Myr) shows strong and
variable lines of He and Si. We also detected a magnetic field in the 12.1 Msun
B1 star OI 201 (NGC 2244; v sin i = 23.5 km/s). The Stokes V profile of this
star does not vary over 5 days, suggesting a long rotational period, a pole-on
orientation, or aligned magnetic and rotation axes. OI 201 is situtated near
the Zero-Age Main Sequence on the HR diagram, and exhibits normal chemical
abundances and no spectrum variability.


title:
Families of LDPC Codes Derived from Nonprimitive BCH Codes and
  Cyclotomic Cosets

abstract:
  Low-density parity check (LDPC) codes are an important class of codes with
many applications. Two algebraic methods for constructing regular LDPC codes
are derived -- one based on nonprimitive narrow-sense BCH codes and the other
directly based on cyclotomic cosets. The constructed codes have high rates and
are free of cycles of length four; consequently, they can be decoded using
standard iterative decoding algorithms. The exact dimension and bounds for the
minimum distance and stopping distance are derived. These constructed codes can
be used to derive quantum error-correcting codes.


title: Spontaneous Quantum Hall Effect in chiral d-density waves

abstract:
  We study the electromagnetic response of a chiral ${\rm d_{xy}+id_{x^2-y^2}}$
charge density wave state. Due to parity (${\cal P}$) and time reversal (${\cal
T}$) violation, Chern-Simons terms emerge in the effective action of the U(1)
gauge field. As a consequence electric and magnetic fields are coupled
providing the possibility of observing the Spontaneous Quantum Hall Effect i.e.
generation of Hall voltage via the sole application of an electric field. We
show how the Chern-Simons terms are induced and discuss the topological origin
of the quantization of Hall conductance.


title: Signs of analyticity in fermion scattering

abstract:
  We show that the signs of the leading irrelevant interactions for Dirac
fermions are constrained by the analytic structure of the S-matrix. If Regge
behavior obtains, negative signs indicate the presence of higher-spin bound
states that spoil the convergence of the dispersion integrals and drive the
corresponding operators relevant. For nucleon-nucleon scattering, the
negativity of some of the low-energy interactions signals the presence of a
spin-1 bound state: the deuteron. We connect the divergence of the dispersion
integral to the "Sommerfeld enhancement" of the cross-section for low-energy
scattering. We also discuss how this illuminates potential pitfalls in using
perturbative methods to understand the dependence of the low-energy nuclear
interaction on the masses of the light quarks. Finally, we suggest the
possibility of applying similar reasoning to the current-current operators in
the electroweak effective lagrangian, where no bound states spoil convergence
of the dispersion relations.


title:
The Petrov and Kaigorodov-Ozsv\'ath Solutions: Spacetime as a Group
  Manifold

abstract:
  The Petrov solution (for $\Lambda=0$) and the Kaigorodov-Ozsv\'ath solution
(for $\Lambda<0$) provide examples of vacuum solutions of the Einstein
equations with simply-transitive isometry groups. We calculate the boundary
stress-tensor for the Kaigorodov-Ozsv\'ath solution in the context of the
adS/CFT correspondence. By giving a matrix representation of the Killing
algebra of the Petrov solution, we determine left-invariant one-forms on the
group. The algebra is shown to admit a two-parameter family of linear
deformations a special case of which gives the algebra of the
Kaigorodov-Ozsv\'ath solution. By applying the method of non-linear
realisations to both algebras, we obtain a Lagrangian of Finsler type from the
general first-order action in both cases. Interpreting the Petrov solution as
the exterior solution of a rigidly rotating dust cylinder, we discuss the
question of creation of CTCs by spinning up such a cylinder. We show geodesic
completeness of the Petrov and Kaigorodov-Ozsv\'ath solutions and determine the
behaviour of geodesics in these spacetimes. The holonomy groups were shown to
be given by the Lorentz group in both cases.


title:
Crystals, quiver varieties and coboundary categories for Kac-Moody
  algebras

abstract:
  Henriques and Kamnitzer have defined a commutor for the category of crystals
of a finite-dimensional complex reductive Lie algebra that gives it the
structure of a coboundary category (somewhat analogous to a braided monoidal
category). Kamnitzer and Tingley then gave an alternative definition of the
crystal commutor, using Kashiwara's involution on Verma crystals, that
generalizes to the setting of symmetrizable Kac-Moody algebras. In the current
paper, we give a geometric interpretation of the crystal commutor using quiver
varieties. Equipped with this interpretation we show that the commutor endows
the category of crystals of a symmetrizable Kac-Moody algebra with the
structure of a coboundary category, answering in the affirmative a question of
Kamnitzer and Tingley.


title:
Chandra spectroscopy of the hot star beta Crucis and the discovery of a
  pre-main-sequence companion

abstract:
  In order to test the O star wind-shock scenario for X-ray production in less
luminous stars with weaker winds, we made a pointed 74 ks observation of the
nearby early B giant, beta Cru (B0.5 III), with the Chandra HETGS. We find that
the X-ray spectrum is quite soft, with a dominant thermal component near 3
million K, and that the emission lines are resolved but quite narrow, with
half-widths of 150 km/s. The forbidden-to-intercombination line ratios of Ne IX
and Mg XI indicate that the hot plasma is distributed in the wind, rather than
confined near the photosphere. It is difficult to understand the X-ray data in
the context of the standard wind-shock paradigm for OB stars, primarily because
of the narrow lines, but also because of the high X-ray production efficiency.
A scenario in which the bulk of the outer wind is shock heated is broadly
consistent with the data, but not very well motivated theoretically. It is
possible that magnetic channeling could explain the X-ray properties, although
no field has been detected on beta Cru. We detected periodic variability in the
hard (hnu > 1 keV) X-rays, modulated on the known optical period of 4.58 hours,
which is the period of the primary beta Cep pulsation mode for this star. We
also have detected, for the first time, an apparent companion to beta Cru at a
projected separation of 4 arcsec. This companion was likely never seen in
optical images because of the presumed very high contrast between it and beta
Cru in the optical. However, the brightness contrast in the X-ray is only 3:1,
which is consistent with the companion being an X-ray active low-mass
pre-main-sequence star. The companion's X-ray spectrum is relatively hard and
variable, as would be expected from a post T Tauri star.


title: Sparticles at the LHC

abstract:
  Sparticle mass hierarchies will play an important role in the type of
signatures that will be visible at the Large Hadron Collider. We analyze these
hierarchies for the four lightest sparticles for a general class of
supergravity unified models including nonuniversalities in the soft breaking
sector. It is shown that out of nearly $10^4$ possibilities of sparticle mass
hierarchies, only a small number survives the rigorous constraints of radiative
electroweak symmetry breaking, relic density and other experimental
constraints. The signature space of these mass patterns at the Large Hadron
Collider is investigated using a large set of final states including
multi-leptonic states, hadronically decaying $\tau$s, tagged $b$ jets and other
hadronic jets. In all, we analyze more than 40 such lepton plus jet and missing
energy signatures along with several kinematical signatures such as missing
transverse momentum, effective mass, and invariant mass distributions of final
state observables. It is shown that a composite analysis can produce
significant discrimination among sparticle mass patterns allowing for a
possible identification of the source of soft breaking. While the analysis
given is for supergravity models, the techniques based on mass pattern analysis
are applicable to wide class of models including string and brane models.


title: Metaplectic Tori over Local Fields

abstract:
  Smooth irreducible representations of tori over local fields have been
parameterized by Langlands, using class field theory and Galois cohomology.
This paper extends this parameterization to central extensions of such tori,
which arise naturally in the setting of nonlinear covers of reductive groups.


title: Quantum gravitational collapse: non-singularity and non-locality

abstract:
  We investigate gravitational collapse in the context of quantum mechanics. We
take primary interest in the behavior of the collapse near the horizon and near
the origin (classical singularity) from the point of view of an infalling
observer. In the absence of radiation, quantum effects near the horizon do not
change the classical conclusions for an infalling observer, meaning the horizon
is not an obstacle for him. However, quantum effects are able to remove the
classical singularity at the origin, since the wave function is non-singular at
the origin. Also, near the classical singularity, some non-local effects become
important. In the Schrodinger equation describing behavior near the origin,
derivatives of the wave function at one point are related to the value of the
wave function at some other distant point.


title: Planetary Systems in Binaries. I. Dynamical Classification

abstract:
  Many recent observational studies have concluded that planetary systems
commonly exist in multiple-star systems. At least ~20% of the known extrasolar
planetary systems are associated with one or more stellar companions. The
orbits of stellar binaries hosting planetary systems are typically wider than
100 AU and often highly inclined with respect to the planetary orbits. The
effect of secular perturbations from such an inclined binary orbit on a coupled
system of planets, however, is little understood theoretically. In this paper
we investigate various dynamical classes of double-planet systems in binaries
through numerical integrations and we provide an analytic framework based on
secular perturbation theories. Differential nodal precession of the planets is
the key property that separates two distinct dynamical classes of multiple
planets in binaries: (1) dynamically-rigid systems in which the orbital planes
of planets precess in concert as if they were embedded in a rigid disk, and (2)
weakly-coupled systems in which the mutual inclination angle between initially
coplanar planets grows to large values on secular timescales. In the latter
case, the quadrupole perturbation from the outer planet induces additional
Kozai cycles and causes the orbital eccentricity of the inner planet to
oscillate with large amplitudes. The cyclic angular momentum transfer from a
stellar companion propagating inward through planets can significantly alter
the orbital properties of the inner planet on shorter timescales. This
perturbation propagation mechanism may offer important constraints on the
presence of additional planets in known single-planet systems in binaries.


title:
An algorithmic complexity interpretation of Lin's third law of
  information theory

abstract:
  Instead of static entropy we assert that the Kolmogorov complexity of a
static structure such as a solid is the proper measure of disorder (or
chaoticity). A static structure in a surrounding perfectly-random universe acts
as an interfering entity which introduces local disruption in randomness. This
is modeled by a selection rule $R$ which selects a subsequence of the random
input sequence that hits the structure. Through the inequality that relates
stochasticity and chaoticity of random binary sequences we maintain that Lin's
notion of stability corresponds to the stability of the frequency of 1s in the
selected subsequence. This explains why more complex static structures are less
stable. Lin's third law is represented as the inevitable change that static
structure undergo towards conforming to the universe's perfect randomness.


title: PP-waves on Superbrane Backgrounds

abstract:
  In this paper we discuss a method of generating supersymmetric solutions of
the Einstein equations. The method involves the embedding of one supersymmetric
spacetime into another. We present two examples with constituent spacetimes
which support "charges", one of which was known previously and the other of
which is new. Both examples have PP-waves as one of the embedding constituents.


title:
Quantum theory of electron tunneling into intersubband cavity polariton
  states

abstract:
  Through a non-perturbative quantum theory, we investigate how the
quasi-electron excitations of a two-dimensional electron gas are modified by
strong coupling to the vacuum field of a microcavity. We show that the
electronic dressed states originate from a Fano-like coupling between the bare
electron states and the continuum of intersubband cavity polariton excitations.
In particular, we calculate the electron spectral function modified by
light-matter interactions and its impact on the electronic injection of
intersubband cavity polaritons. The domain of validity of the present
theoretical results is critically discussed. We show that resonant electron
tunneling from a narrow-band injector can selectively excite superradiant
states and produce efficient intersubband polariton electroluminescence.


title:
Magnetization depinning transition, anisotropic magnetoresistance and
  inplane anisotropy in two polytypes of La$_{2 / 3}$Sr$_{1 / 3}$MnO$_{3}$
  epitaxial films

abstract:
  The isothermal magnetoresistance [R($\theta$)] of [001] and [110] epitaxial
films of La$_{2 / 3}$Sr$_{1 / 3}$MnO$_{3}$ measured as a function of the angle
$\theta$ between current ($\vec{I}$) and magnetic field ($\vec{H}$), both in
the plane of the film, is measured at several temperatures between 10 and 300K.
The magnetic easy axis of these polytypes is intimately related to the
orientation of Mn - O - Mn bonds with respect to the crystallographic axis on
the plane of the substrate and energy equivalence of some of these axes. The
magnetization vector ($\vec{M}$) of the [001] and [110] type films is pinned
along the [110] and [001] directions respectively at low fields. A
magnetization orientation phase transition (MRPT) which manifests itself as a
discontinuity and hysteresis in $R(\psi)$ where $\psi$ is the angle between
$\vec{H}$ and the easy axis for the $\vec{H}$ below a critical value
$\vec{H}^*$ has been established. The boundary of the pinned and depinned phase
on the H-T plane has been established. The highly robust pinning of
magnetization seen in [110] films is related to their uniquely defined easy
axis. The isothermal resistance R$_\bot$ and R$_\|$ for $\vec{I} \bot \vec{H}$
and $\vec{I} \| \vec{H}$, respectively for both polytypes follows the
inequality R$_\bot >$ R$_\|$ for all ranges of fields ($0 \leq H \leq 3500Oe$)
and temperatures (10K - 300K). A full fledged analysis of the rotational
magnetoresistance is carried out in the framework of D\"oring theory for MR in
single crystal samples. Strong deviations from the predicted angular dependence
are seen in the irreversible regime of magnetization.


title: Meissner effect without superconductivity from a chiral d-density wave

abstract:
  We demonstrate that the formation of a chiral d-density wave (CDDW) state
generates a Topological Meissner effect (TME) in the absence of any kind of
superconductivity. The TME is identical to the usual superconducting Meissner
effect but it appears only for magnetic fields perpendicular to the plane while
it is absent for in plane fields. The observed enhanced diamagnetic signals in
the non-superconducting pseudogap regime of the cuprates may find an
alternative interpretation in terms of a TME, originating from a chiral
d-density wave pseudogap.


title:
Confirmation of the remarkable compactness of massive quiescent galaxies
  at z~2.3: early-type galaxies did not form in a simple monolithic collapse

abstract:
  Using deep near-infrared spectroscopy Kriek et al. (2006) found that ~45% of
massive galaxies at z~2.3 have evolved stellar populations and little or no
ongoing star formation. Here we determine the sizes of these quiescent galaxies
using deep, high-resolution images obtained with HST/NIC2 and laser guide
star-assisted Keck/AO. Considering that their median stellar mass is 1.7x10^11
Solar masses the galaxies are remarkably small, with a median effective radius
of 0.9 kpc. Galaxies of similar mass in the nearby Universe have sizes of ~5
kpc and average stellar densities which are two orders of magnitude lower than
the z~2.3 galaxies. These results extend earlier work at z~1.5 and confirm
previous studies at z>2 which lacked spectroscopic redshifts and imaging of
sufficient resolution to resolve the galaxies. Our findings demonstrate that
fully assembled early-type galaxies make up at most ~10% of the population of
K-selected quiescent galaxies at z~2.3, effectively ruling out simple
monolithic models for their formation. The galaxies must evolve significantly
after z~2.3, through dry mergers or other processes, consistent with
predictions from hierarchical models.


title:
For each $\alpha$ > 2 there is an infinite binary word with critical
  exponent $\alpha$

abstract: For each $\alpha > 2$ there is a binary word with critical exponent $\alpha$.


title: On local-to-global spectral sequences for the cohomology of diagrams

abstract:
  The aim of this paper is to construct and examine three candidates for
local-to-global spectral sequences for the cohomology of diagrams of algebras
with directed indexing. In each case, the $E^2$ -terms can be viewed as a type
of local cohomology relative to a map or an object in the diagram.


title: Manifestations of the Roton Mode in Dipolar Bose-Einstein Condensates

abstract:
  We investigate the structure of trapped Bose-Einstein condensates (BECs) with
long-range anisotropic dipolar interactions. We find that a small perturbation
in the trapping potential can lead to dramatic changes in the condensate's
density profile for sufficiently large dipolar interaction strengths and trap
aspect ratios. By employing perturbation theory, we relate these oscillations
to a previously-identified "roton-like" mode in dipolar BECs. The same physics
is responsible for radial density oscillations in vortex states of dipolar BECs
that have been predicted previously.


title: General Relativistic Effects in Atom Interferometry

abstract:
  Atom interferometry is now reaching sufficient precision to motivate
laboratory tests of general relativity. We begin by explaining the
non-relativistic calculation of the phase shift in an atom interferometer and
deriving its range of validity. From this we develop a method for calculating
the phase shift in general relativity. This formalism is then used to find the
relativistic effects in an atom interferometer in a weak gravitational field
for application to laboratory tests of general relativity. The potentially
testable relativistic effects include the non-linear three-graviton coupling,
the gravity of kinetic energy, and the falling of light. We propose
experiments, one currently under construction, that could provide a test of the
principle of equivalence to 1 part in 10^15 (300 times better than the present
limit), and general relativity at the 10% level, with many potential future
improvements. We also consider applications to other metrics including the
Lense-Thirring effect, the expansion of the universe, and preferred frame and
location effects.


title: Planet Formation by Concurrent Collapse

abstract:
  After reviewing the difficulties faced by the conventional theory of planet
formation (based upon the aggregation of microscopic dust particles), we
describe an alternative hypothesis. We propose that planets form by
gravitational collapse at the same time as the star about which they orbit.
This 'concurrent collapse' hypothesis avoids theoretical difficulties
associated with the conventional model and suggests satisfying explanations for
various poorly understood phenomena. We introduce new explanations for FU
Orionis outbursts seen in young stars, the discovery of exoplanets with
eccentric orbits and the existence of small rocky objects such as chondrules in
the solar system.


title:
Narrow associated QSO absorbers: clustering, outflows and the
  line-of-sight proximity effect

abstract:
  Using data from the Sloan Digital Sky Survey data release 3 (SDSS DR3) we
investigate how narrow (<700km/s) CIV and MgII quasar absorption line systems
are distributed around quasars. The CIV absorbers lie in the redshift range 1.6
< z < 4 and the MgII absorbers in the range 0.4<z<2.2. By correlating absorbers
with quasars on different but neighbouring lines-of-sight, we measure the
clustering of absorbers around quasars on comoving scales between 4 and 30Mpc.
The observed comoving correlation lengths are r_o~5h^-1Mpc, similar to those
observed for bright galaxies at these redshifts. Comparing with correlations
between absorbers and the quasars in whose spectra they are identified then
implies: (i) that quasars destroy absorbers to comoving distances of ~300kpc
(CIV) and ~800kpc (MgII) along their lines-of-sight; (ii) that >40% of CIV
absorbers within 3,000km/s of the QSO are not a result of large-scale
clustering but rather are directly associated with the quasar itself; (iii)
that this intrinsic absorber population extends to outflow velocities of order
12,000km/s; (iv) that this outflow component is present in both radio-loud and
radio-quiet quasars; and (v) that a small high-velocity outflow component is
observed in the MgII population, but any further intrinsic absorber component
is undetectable in our clustering analysis. We also find an indication that
absorption systems within 3,000km/s are more abundant for radio-loud than for
radio-quiet quasars. This suggests either that radio-loud objects live in more
massive halos, or that their radio activity generates an additional
low-velocity outflow, or both.