title:
Qualitative and quantitative features of orbits of massive particles and
  photons moving in Wyman geometry

abstract:
  The Wyman's solution depends on two parameters, the mass $M$ and the scalar
charge $\sigma$. If one fixes $M$ to a positive value, say $M_0$, and let
$\sigma^2$ take values along the real line it describes three different types
of spacetimes. For $\sigma^2 >0$ the spacetimes are naked singularities, for
$\sigma^2 = 0$ one has the Schwarzschild black hole of mass $M_0$ and finally
for $-M_0^2 \leq \sigma^2 < 0$ one has wormhole spacetimes. In the present
work, we shall study qualitative and quantitative features of orbits of massive
particles and photons moving in the naked singularity and wormhole spacetimes
of the Wyman solution. These orbits are the timelike geodesics for massive
particles and null geodesics for photons. Combining the four geodesic equations
with an additional equation derived from the line element, we obtain an
effective potential for the massive particles and a different effective
potential for the photons. We investigate all possible types of orbits, for
massive particles and photons, by studying the appropriate effective potential.
We notice that for certain values of $\sigma^2 >0$, there is an infinity
potential wall that prevents both massive particles and photons ever to reach
the naked singularity. We notice, also, that for certain values of $-M_0^2 \leq
\sigma^2 < 0$, the potential is finite everywhere, which allows massive
particles and photons moving from one wormhole asymptotically flat region to
the other. We also compute the radial timelike and null geodesics for massive
particles and photons, respectively, moving in the naked singularities and
wormholes spacetimes.


title: A connection between viscous profiles and singular ODEs

abstract:
  We deal with the viscous profiles for a class of mixed hyperbolic-parabolic
systems. We focus, in particular, on the case of the compressible Navier Stokes
equation in one space variable written in Eulerian coordinates. We describe the
link between these profiles and a singular ordinary differential equation in
the form $$ dV / dt = F(V) / z (V) . $$ Here $V \in R^d$ and the function F
takes values into $R^d$ and is smooth. The real valued function z is as well
regular: the equation is singular in the sense that z (V) can attain the value
0.


title: Groups that do and do not have context-sensitive word problem

abstract:
  We prove that a group has word problem that is a growing context-sensitive
language precisely if its word problem can be solved using a non-deterministic
Cannon's algorithm (the deterministic algorithms being defined by Goodman and
Shapiro). We generalise their results to find many examples of groups not
admitting non-deterministic Cannon's algorithms. This adds to the examples of
Kambites and Otto of groups separating context-sensitive and growing
context-sensitive word problems, and provides a new language-theoretic
separation result.


title: Direct Measurements, Acceleration and Propagation of Cosmic Rays

abstract:
  This paper summarizes highlights of the OG1 session of the 30th International
Cosmic Ray Conference, held in Merida (Yucatan, Mexico). The subsessions
(OG1.1, OG1.2, OG1.3, OG1.4 and OG1.5) summarized here were mainly devoted to
direct measurements, acceleration and propagation of cosmic rays.


title:
SZ effect from radio-galaxy lobes: astrophysical and cosmological
  relevance

abstract:
  We derive the SZ effect arising in radio-galaxy lobes that are filled with
high-energy, non-thermal electrons. We provide here quantitative estimates for
SZ effect expected from the radio galaxy lobes by normalizing it to the
Inverse-Compton light, observed in the X-ray band, as produced by the
extrapolation to low energies of the radio emitting electron spectrum in these
radio lobes. We compute the spectral and spatial characteristics of the SZ
effect associated to the radio lobes of two distant radio galaxies (3C294 and
3C432) recently observed by Chandra, and we further discuss its detectability
with the next generation microwave and sub-mm experiments with arcsec and $\sim
\mu$K sensitivity. We finally highlight the potential use of the SZE from
radio-galaxy lobes in the astrophysical and cosmological context.


title:
Quantum evolution across singularities: the case of geometrical
  resolutions

abstract:
  We continue the study of time-dependent Hamiltonians with an isolated
singularity in their time dependence, describing propagation on singular
space-times. In previous work, two of us have proposed a "minimal subtraction"
prescription for the simplest class of such systems, involving Hamiltonians
with only one singular term. On the other hand, Hamiltonians corresponding to
geometrical resolutions of space-time tend to involve multiple operator
structures (multiple types of dependence on the canonical variables) in an
essential way.
  We consider some of the general properties of such (near-)singular
Hamiltonian systems, and further specialize to the case of a free scalar field
on a two-parameter generalization of the null-brane space-time. We find that
the singular limit of free scalar field evolution exists for a discrete subset
of the possible values of the two parameters. The coordinates we introduce
reveal a peculiar reflection property of scalar field propagation on the
generalized (as well as the original) null-brane. We further present a simple
family of pp-wave geometries whose singular limit is a light-like hyperplane
(discontinuously) reflecting the positions of particles as they pass through
it.


title:
Radial velocity mapping of Paczy\'nski's star AW UMa: Not a contact
  binary

abstract:
  We present two-dimensional (radial velocity, orbital phase) spectroscopic
results for the very low mass-ratio close binary AW UMa which strongly indicate
that the spectroscopic mass ratio (q_sp = 0.10) does not agree with the
photometrically derived one and that the widely adopted contact binary model
appears to experience serious inconsistencies and limitations for this object.
AW UMa is compared with V566 Oph (q_sp = 0.26) which we found to behave
according to the contact model. Observed broadening functions of AW UMa can be
interpreted by a very strong limb darkening and/or non-solid body rotation of
the dominant primary component; the former assumption is unphysical while the
differential rotation is not supported by an apparent stability of localized,
dark features on the outer side of the primary. There are indications of the
existence of an equatorial belt encompassing the whole system. All deficiencies
in the interpretation and the discrepancy between the photometric and
spectroscopic mass ratio of AW UMa can be solved within a new model of AW UMa
where both components are detached and the system is submerged in a stream of
hot, optically thick matter which mimics the stellar contact. While the masses
and their ratio are correctly given by spectroscopy, the photometric picture is
heavily modified by the matter engulfing both stars in the equatorial plane.


title: A Relativistic Wave Equation for the Skyrmion

abstract:
  We propose a relativistically invariant wave equation for the Skyrme soliton.
It is a differential equation on the space $R^{1,3}\times S^3$ which is
invariant under the Lorentz group and isospin. The internal variable valued in
$SU(2)\approx S^3$ describes the orientation of the soliton. The mass of a
particle of spin and isospin both equal to $j={1\over 2},{3\over 2}...$ is
predicted to be $M=m\sqrt{1+K_2j(j+1)\over 1+K_1j(j+1)}$ which agrees with the
known spectrum for low angular momentum. The iso-scalar magnetic moment is
predicted to be $-{K_1\over 4m}{\mathbf \Sigma}$, where ${\mathbf \Sigma}$ is
the spin.


title:
Discovery of an open cluster with a possible physical association with a
  planetary nebula

abstract:
  We report the discovery of a new open cluster (OC) in the Galaxy at
$\ell=167.0^\circ$ and $b=-1.0^\circ$. Its field includes the planetary nebula
(PN) PK 167-0.1. We study the possible associations of the PN/OC pairs NGC
2818/NGC 2818A, NGC 2438/M 46 (NGC 2437), PK 6+2.5/NGC 6469, as well as of the
PN PK 167-0.1 with New Cluster 1. The analyses are based on near-infrared
colour-magnitude diagrams (CMDs) and stellar radial density profiles (RDPs).
NGC 6469 is located in a heavily contaminated bulge field. The CMD morphology,
especially for the latter two cases, is defined with a field star
decontamination algorithm applied to the 2MASS \jj, \hh, and \ks photometry.
Field decontamination for the OCs NGC 2818A and M 46 produced better defined
CMDs and more accurate cluster parameters than in the literature. Those pieces
of evidence point to M 46 as physically associated with the PN NGC 2438. The
same occurs for the OC NGC 2818A and the PN NGC 2818, however previous radial
velocity arguments indicate that they are not associated. The OC NGC 6469 does
not appear to be associated with the PN PK 6+2.5, which probably belongs to the
bulge. Finally, the distance of the OC New Cluster 1 is consistent with a
physical association with the PN PK 167-0.1.


title: The cluster category of a canonical algebra

abstract:
  We study the cluster category of a canonical algebra A in terms of the
hereditary category of coherent sheaves over the corresponding weighted
projective line X. As an application we determine the automorphism group of the
cluster category and show that the cluster-tilting objects form a cluster
structure in the sense of Buan-Iyama-Reiten-Scott. The tilting graph of the
sheaf category always coincides with the tilting or exchange graph of the
cluster category. We show that this graph is connected if the Euler
characteristic of X is non-negative, or equivalently, if A is of tame (domestic
or tubular) representation type.


title: Microwave-induced coupling of superconducting qubits

abstract:
  We investigate the quantum dynamics of a system of two coupled
superconducting qubits under microwave irradiation. We find that, with the
qubits operated at the charge co-degeneracy point, the quantum evolution of the
system can be described by a new effective Hamiltonian which has the form of
two coupled qubits with tunable coupling between them. This Hamiltonian can be
used for experimental tests on macroscopic entanglement and for implementing
quantum gates.


title: Muons and Neutrinos 2007

abstract:
  This paper is the written version of the rapporteur talk on Section HE-2,
muons and neutrinos, presented at the 30th International Cosmic Ray Conference,
Merida, Yucatan, July 11, 2007. Topics include atmospheric muons and neutrinos,
solar neutrinos and astrophysical neutrinos as well as calculations and
instrumentation related to these topics.


title:
Self-organizing patterns maintained by competing associations in a
  six-species predator-prey model

abstract:
  Formation and competition of associations are studied in a six-species
ecological model where each species has two predators and two prey. Each site
of a square lattice is occupied by an individual belonging to one of the six
species. The evolution of the spatial distribution of species is governed by
iterated invasions between the neighboring predator-prey pairs with species
specific rates and by site exchange between the neutral pairs with a
probability $X$. This dynamical rule yields the formation of five associations
composed of two or three species with proper spatiotemporal patterns. For large
$X$ a cyclic dominance can occur between the three two-species associations
whereas one of the two three-species associations prevails in the whole system
for low values of $X$ in the final state. Within an intermediate range of $X$
all the five associations coexist due to the fact that cyclic invasions between
the two-species associations reduce their resistance temporarily against the
invasion of three-species associations.


title: A Neyman-Pearson Approach to Universal Erasure and List Decoding

abstract:
  When information is to be transmitted over an unknown, possibly unreliable
channel, an erasure option at the decoder is desirable. Using
constant-composition random codes, we propose a generalization of Csiszar and
Korner's Maximum Mutual Information decoder with erasure option for discrete
memoryless channels. The new decoder is parameterized by a weighting function
that is designed to optimize the fundamental tradeoff between undetected-error
and erasure exponents for a compound class of channels. The class of weighting
functions may be further enlarged to optimize a similar tradeoff for list
decoders -- in that case, undetected-error probability is replaced with average
number of incorrect messages in the list. Explicit solutions are identified.
  The optimal exponents admit simple expressions in terms of the sphere-packing
exponent, at all rates below capacity. For small erasure exponents, these
expressions coincide with those derived by Forney (1968) for symmetric
channels, using Maximum a Posteriori decoding. Thus for those channels at
least, ignorance of the channel law is inconsequential. Conditions for
optimality of the Csiszar-Korner rule and of the simpler
empirical-mutual-information thresholding rule are identified. The error
exponents are evaluated numerically for the binary symmetric channel.


title:
Dihadron azimuthal correlations in Au+Au collisions at sqrt(s_NN)=200
  GeV

abstract:
  Azimuthal angle (Delta phi) correlations are presented for a broad range of
transverse momentum (0.4 < pT < 10 GeV/c) and centrality (0-92%) selections for
charged hadrons from di-jets in Au+Au collisions at sqrt(s_NN) = 200 GeV. With
increasing pT, the away-side Delta phi distribution evolves from a broad and
relatively flat shape to a concave shape, then to a convex shape. Comparisons
to p+p data suggest that the away-side distribution can be divided into a
partially suppressed head region centered at Delta phi ~ \pi, and an enhanced
shoulder region centered at Delta phi ~ \pi \pm 1:1. The pT spectrum for the
associated hadrons in the head region softens toward central collisions. The
spectral slope for the shoulder region is independent of centrality and trigger
pT . The properties of the near-side distributions are also modified relative
to those in p + p collisions, reflected by the broadening of the jet shape in
Delta phi and Delta eta, and an enhancement of the per-trigger yield. However,
these modifications seem to be limited to pT < 4 GeV/c, above which both the
dihadron pair shape and per-trigger yield become similar to p + p collisions.
These observations suggest that both the away- and near-side distributions
contain a jet fragmentation component which dominates for pT \ge 5GeV and a
medium-induced component which is important for pT \le 4 GeV/c. We also
quantify the role of jets at intermediate and low pT through the yield of
jet-induced pairs in comparison to binary scaled p + p pair yield. The yield of
jet-induced pairs is suppressed at high pair proxy energy (sum of the pT
magnitudes of the two hadrons) and is enhanced at low pair proxy energy. The
former is consistent with jet quenching; the latter is consistent with the
enhancement of soft hadron pairs due to transport of lost energy to lower pT.


title: RICAP-07: Summary comments

abstract:
  The Roma International Conference on Astroparticle Physics covered gamma-ray
astronomy, air shower experiments and neutrino astronomy on three successive
days. I organize my brief summary comments into four topics that cut across
these three techniques. They are detector calibration, galactic sources,
extra-galactic sources and cosmology.


title: Non-thermal emission from secondary pairs in close TeV binary systems

abstract:
  Massive hot stars produce dense ultraviolet (UV) photon fields in their
surroundings. If a very high-energy (VHE) gamma-ray emitter is located close to
the star, then gamma-rays are absorbed in the stellar photon field, creating
secondary (electron-positron) pairs. We study the broadband emission of these
secondary pairs in the stellar photon and magnetic fields. Under certain
assumptions on the stellar wind and the magnetic field in the surroundings of a
massive hot star, we calculate the steady state energy distribution of
secondary pairs created in the system and its radiation from radio to
gamma-rays. Under the ambient magnetic field, possibly high enough to suppress
electromagnetic (EM) cascading, the energy of secondary pairs is radiated via
synchrotron and single IC scattering producing radio-to-gamma-ray radiation.
The synchrotron spectral energy distribution (SED) is hard, peaks around X-ray
energies, and becomes softer. The IC SED is hard as well and peaks around 10
GeV, becoming also softer at higher energies due to synchrotron loss dominance.
The radio emission from secondary pairs is moderate and detectable as a
point-like and/or extended source. In X-rays, the secondary pair synchrotron
component may be dominant. At energies <10 GeV, the secondary pair IC radiation
may be the dominant primary gamma-ray emission and possibly detectable by the
next generation of instruments.


title:
Macroscopic dimension of the $\ell^p$-ball with respect to the
  $\ell^q$-norm

abstract:
  We show estimates of the "macroscopic dimension" of the $\ell^p$-ball with
respect to the $\ell^q$-norm.


title: Simplified measurement of the Bell parameter within quantum mechanics

abstract:
  We point out that, if one accepts the validity of quantum mechanics, the Bell
parameter for the polarization state of two photons can be measured in a
simpler way than by the standard procedure [Clauser, Horne, Shimony, and Holt,
Phys. Rev. Lett. 23, 880 (1969)]. The proposed method requires only two
measurements with parallel linear-polarizer settings for Alice and Bob at 0 and
45 degrees, and yields a significantly smaller statistical error for a large
Bell parameter.


title:
Generalized optical potential for weakly bound nuclei. I. Two-cluster
  projectiles

abstract:
  A generalized optical potential for elastic scattering induced by light
nuclei is calculated within the Feshbach projection operator method. The model
explicitly takes into account the contribution of the projectile break-up
continuum treated within a microscopic few-cluster model. In this work we
formulate the model, deriving an explicit expression for the optical potential,
and show ability of the model applying it to deuteron elastic scattering.


title: Exploring the quantum vacuum with cylinders

abstract:
  We review recent work on the Casimir interaction energy between cylindrical
shells. We include proposals for future experiments involving cylinders, such
us a null experiment using quasi-concentric cylinders, a cylinder in front a
conducting plate, and a cylindrical version of the rack and pinion powered by
Casimir lateral force. We also present an exact formula for the theoretical
evaluation of the vacuum interaction energy between eccentric cylindrical
shells, and describe improved analytical and numerical evaluations for the
particular case of concentric cylinders.


title: Soft X-ray Spectroscopy of the Cygnus Loop Supernova Remnant

abstract:
  The Cygnus X-ray Emission Spectroscopic Survey (CyXESS) sounding rocket
payload was launched from White Sands Missile Range on 2006 November 20 and
obtained a high resolution spectrum of the Cygnus Loop supernova remnant in the
soft X-rays. The novel X-ray spectrograph incorporated a wire-grid collimator
feeding an array of gratings in the extreme off-plane mount which ultimately
dispersed the spectrum onto Gaseous Electron Multiplier (GEM) detectors. This
instrument recorded 65 seconds of usable data between 43-49.5 \AA in two
prominent features. The first feature near 45 \AA is dominated by the He-like
triplet of \ion{O}{7} in second order with contributions from \ion{Mg}{10} and
\ion{Si}{9}-\ion{Si}{12} in first order, while the second feature near 47.5 \AA
is first order \ion{S}{9} and \ion{S}{10}. Fits to the spectra give an
equilibrium plasma at $\log(T)=6.2$ ($kT_e=0.14$ keV) and near cosmic
abundances. This is consistent with previous observations, which demonstrated
that the soft x-ray emission from the Cygnus Loop is dominated by interactions
between the initial blast wave with the walls of a precursor formed cavity
surrounding the Cygnus Loop and that this interaction can be described using
equilibrium conditions.


title: Metric fluctuations and the Weak Equivalence Principle

abstract:
  We describe space--time fluctuations by means of small fluctuations of the
metric on a given background metric. From a minimally coupled Klein--Gordon
equation we obtain within a weak-field approximation up to second order and an
averaging procedure over a finite space--time scale given by the quantum
particle in the non--relativistic limit a modified Schr\"odinger equation. The
dominant modification consists in an anomalous inertial mass tensor which
depends on the type of particle and on the fluctuation scenario. The scenario
considered in this paper is a most simple picture of spacetime fluctuations and
gives an existence proof for an apparent violation of the weak equivalence
principle and, in general, for a violation of Lorentz invariance.


title: Nonstandard Higgs Boson Decays

abstract:
  This review summarizes the motivations for and phenomenological consequences
of nonstandard Higgs boson decays, with emphasis on final states containing a
pair of non-Standard-Model particles that subsequently decay to Standard Model
particles. Typically these non-Standard-Model particles are part of a
``hidden'' sector, for example a pair of neutral Higgs bosons or a pair of
unstable neutralinos. We emphasize that such decays allow for a Higgs
substantially below the Standard Model Higgs LEP limit of 114 GeV. This in turn
means that the ``fine-tuning'' problems of many Beyond the Standard Model (BSM)
theories, in particular supersymmetric models, can be eliminated while
achieving excellent consistency with precision electroweak data which favor a
Higgs boson with mass below $100\gev$ and standard $WW$, $ZZ$, and top
couplings.


title:
Energy dependence of pi-zero production in Cu+Cu collisions at
  sqrt(s_NN) = 22.4, 62.4, and 200 GeV

abstract:
  Neutral pion transverse momentum (pT) spectra at mid-rapidity (|y| < 0.35)
were measured in Cu+Cu collisions at \sqrt s_NN = 22.4, 62.4, and 200 GeV.
Relative to pi -zero yields in p+p collisions scaled by the number of inelastic
nucleon-nucleon collisions (Ncoll) at the respective energies, the pi-zero
yields for pT \ge 2 GeV/c in central Cu+Cu collisions at 62.4 and 200 GeV are
suppressed, whereas an enhancement is observed at 22.4 GeV. A comparison with a
jet quenching model suggests that final state parton energy loss dominates in
central Cu+Cu collisions at 62.4 GeV and 200 GeV, while the enhancement at 22.4
GeV is consistent with nuclear modifications in the initial state alone.


title: Large attractors in cooperative bi-quadratic Boolean networks. Part II

abstract:
  Boolean networks have been the object of much attention, especially since S.
Kauffman proposed them in the 1960's as models for gene regulatory networks.
These systems are characterized by being defined on a Boolean state space and
by simultaneous updating at discrete time steps. Of particular importance for
biological applications are networks in which the indegree for each variable is
bounded by a fixed constant, as was stressed by Kauffman in his original
papers.
  An important question is which conditions on the network topology can rule
out exponentially long periodic orbits in the system. In this paper we consider
cooperative systems, i.e. systems with positive feedback interconnections among
all variables, which in a continuous setting guarantees a very stable dynamics.
In Part I of this paper we presented a construction that shows that for an
arbitrary constant 0<c<2 and sufficiently large n there exist n-dimensional
Boolean cooperative networks in which both the indegree and outdegree of each
for each variable is bounded by two (bi-quadratic networks) and which
nevertheless contain periodic orbits of length at least c^n.
  In this part, we prove an inverse result showing that for sufficiently large
n and for 0<c<2 sufficiently close to 2, any n-dimensional cooperative,
bi-quadratic Boolean network with a cycle of length at least c^n must have a
large proportion of variables with indegree 1. Such systems therefore share a
structural similarity to the systems constructed in Part I.


title: Subordinated discrete semigroups of operators

abstract:
  Given a power-bounded linear operator T in a Banach space and a probability F
on the non-negative integers, one can form a `subordinated' operator S = \sum_k
F(k) T^k. We obtain asymptotic properties of the subordinated discrete
semigroup (S^n: n=1,2,...) under certain conditions on F. In particular, we
study probabilities F with the property that S satisfies the Ritt resolvent
condition whenever T is power-bounded. Examples and counterexamples of this
property are discussed. The hypothesis of power-boundedness of T can sometimes
be replaced by the weaker Kreiss resolvent condition.


title:
Simultaneous measurements of electronic conduction and Raman response in
  molecular junctions

abstract:
  Electronic conduction through single molecules is affected by the molecular
electronic structure as well as by other information that is extremely
difficult to assess, such as bonding geometry and chemical environment. The
lack of an independent diagnostic technique has long hampered single-molecule
conductance studies. We report simultaneous measurement of the conductance and
the Raman spectra of nanoscale junctions used for single-molecule electronic
experiments. Blinking and spectral diffusion in the Raman response of both
para-mercaptoaniline and a fluorinated oligophenylyne ethynylene correlate in
time with changes in the electronic conductance. Finite difference time domain
calculations confirm that these correlations do not result from the conductance
modifying the Raman enhancement. Therefore, these observations strongly imply
that multimodal sensing of individual molecules is possible in these
mass-producible nanostructures.


title: A Limit on the Number Density of Bright z~7 Galaxies

abstract:
  We present a survey of bright optical dropout sources in two deep,
multiwavelength surveys comprising eleven widely-separated fields, aimed at
constraining the galaxy luminosity function at z~7 for sources at 5-10L*(z=6).
Our combined survey area is 225 arcmin^2 to a depth of J=24.2 (AB, 3 sigma) and
135 arcmin^2 to J=25.3 (AB, 4 sigma). We find that infrared data longwards of 2
microns is essential for classifying optical dropout sources, and in particular
for identifying cool Galactic star contaminants. Our limits on the number
density of high redshift sources are consistent with current estimates of the
Lyman break galaxy luminosity function at z=6.


title:
Are the black hole masses in Narrow Line Seyfert 1 galaxies actually
  small?

abstract:
  Narrow Line Seyfert 1 galaxies (NLS1s) are generally considered peculiar
objects among the broad class of Type 1 active galactic nuclei, due to the
relatively small width of the broad lines, strong X-ray variability, soft X-ray
continua, weak [OIII], and strong FeII line intensities. The mass M_BH of the
central massive black hole (MBH) is claimed to be lighter than expected from
known MBH-host galaxy scaling relations, while the accretion rate onto the MBH
larger than the average value appropriate to Seyfert 1 galaxies. In this
Letter, we show that NLS1 peculiar M_BH and L/L_Edd turn out to be fairly
standard, provided that the broad line region is allowed to have a disc-like,
rather than isotropic, geometry. Assuming that NLS1s are rather ``normal''
Seyfert 1 objects seen along the disc axis, we could estimate the typical
inclination angles from the fraction of Seyfert 1 classified as NLS1s, and
compute the geometrical factor relating the observed FWHM of broad lines to the
virial mass of the MBH. We show that the geometrical factor can fully account
for the "black hole mass deficit" observed in NLS1s, and that L/L_Edd is (on
average) comparable to the value of the more common broad line Seyfert 1
galaxies.


title: Planet Shadows in Protoplanetary Disks. I: Temperature Perturbations

abstract:
  Planets embedded in optically thick passive accretion disks are expected to
produce perturbations in the density and temperature structure of the disk. We
calculate the magnitudes of these perturbations for a range of planet masses
and distances. The model predicts the formation of a shadow at the position of
the planet paired with a brightening just beyond the shadow. We improve on
previous work on the subject by self-consistently calculating the temperature
and density structures under the assumption of hydrostatic equilibrium and
taking the full three-dimensional shape of the disk into account rather than
assuming a plane-parallel disk. While the excursion in temperatures is less
than in previous models, the spatial size of the perturbation is larger. We
demonstrate that a self-consistent calculation of the density and temperature
structure of the disk has a large effect on the disk model. In addition, the
temperature structure in the disk is highly sensitive to the angle of incidence
of stellar irradition at the surface, so accurately calculating the shape of
the disk surface is crucial for modeling the thermal structure of the disk.


title: Non-dipolar magnetic fields in Ap stars

abstract:
  An arbitrary initial magnetic field in an A star evolves into a stable
equilibrium. Simulations are presented of the formation of non-axisymmetric
equilibria consisting of twisted flux tubes meandering under the surface of the
star, and analytic arguments are given relating the stability and form of these
equilibria. These results may help to explain observations of Ap stars with
very non-dipolar fields. This work is also applicable to other essentially
non-convective stars such as white dwarfs and neutron stars.


title: Intrinsic Properties of Low-z SDSS Galaxies

abstract:
  Galaxies are seen from different viewing angles and their observed properties
change as a function of viewing angle. In many circumstances we would rather
know the intrinsic properties of galaxies - those properties that do not depend
on viewing angle. For a large sample of galaxies it is possible to recover the
intrinsic properties of galaxies, statistically, by looking for correlations
with galaxy inclination, and then applying a correction to remove those
dependencies. Studying the intrinsic properties of galaxies can give a
different impression of the galaxy population and help avoid the mistake of
connecting observed properties to quantities that don't depend on inclination
like halo mass.


title: Entanglement Entropy and Spatial Geometry

abstract:
  The entanglement entropy in a quantum field theory between two regions of
space has been shown in simple cases to be proportional to the volume of the
hypersurface separating the regions. We prove that this is true for a free
scalar field in an arbitrary geometry with purely spatial curvature and obtain
a complete asymptotic expansion for the entropy.


title: Finding Evidence for Massive Neutrinos using 3D Weak Lensing

abstract:
  In this paper we investigate the potential of 3D cosmic shear to constrain
massive neutrino parameters. We find that if the total mass is substantial
(near the upper limits from LSS, but setting aside the Ly alpha limit for now),
then 3D cosmic shear + Planck is very sensitive to neutrino mass and one may
expect that a next generation photometric redshift survey could constrain the
number of neutrinos N_nu and the sum of their masses m_nu to an accuracy of
dN_nu ~ 0.08 and dm_nu ~ 0.03 eV respectively. If in fact the masses are close
to zero, then the errors weaken to dN_nu ~ 0.10 and dm_nu~0.07 eV. In either
case there is a factor 4 improvement over Planck alone. We use a Bayesian
evidence method to predict joint expected evidence for N_nu and m_nu. We find
that 3D cosmic shear combined with a Planck prior could provide `substantial'
evidence for massive neutrinos and be able to distinguish `decisively' between
many competing massive neutrino models. This technique should `decisively'
distinguish between models in which there are no massive neutrinos and models
in which there are massive neutrinos with |N_nu-3| > 0.35 and m_nu > 0.25 eV.
We introduce the notion of marginalised and conditional evidence when
considering evidence for individual parameter values within a multi-parameter
model.


title: Chiral Gravity in Three Dimensions

abstract:
  Three dimensional Einstein gravity with negative cosmological constant
-1/\ell^2 deformed by a gravitational Chern-Simons action with coefficient
1/\mu is studied in an asymptotically AdS_3 spacetime. It is argued to violate
unitary or positivity for generic \mu due to negative-energy massive gravitons.
However at the critical value \mu\ell=1, the massive gravitons disappear and
BTZ black holes all have mass and angular momentum related by \ell M=J. The
corresponding chiral quantum theory of gravity is conjectured to exist and be
dual to a purely right-moving boundary CFT with central charges
(c_L,c_R)=(0,3\ell /G).


title:
The needle in the haystack - Where to look for more isolated cooling
  neutron stars

abstract:
  Context: Isolated cooling neutron stars with thermal X-ray emission remain
rarely detected objects despite many searches investigating the ROSAT data.
  Aims: We simulate the population of close-by young cooling neutron stars to
explain the current observational results. Given the inhomogeneity of the
neutron star distribution on the sky it is particularly interesting to identify
promising sky regions with respect to on-going and future searches.
  Methods: Applying a population synthesis model the inhomogeneity of the
progenitor distribution and the inhomogeneity of the X-ray absorbing
interstellar medium are considered for the first time. The total number of
observable neutron stars is derived with respect to ROSAT count rates. In
addition, we present sky maps of neutron star locations and discuss age and
distance distributions of the simulated neutron stars. Implications for future
searches are discussed.
  Results: With our advanced model we can successfully explain the observed
logN - logS distribution of close-by neutron stars. Cooling neutron stars will
be most abundant in the directions of rich OB associations. New candidates are
expected to be identified behind the Gould Belt, in particular in the
Cygnus-Cepheus region. They are expected to be on average younger and then
hotter than the known population of isolated cooling neutron stars. In
addition, we propose to use data on runaway stars to search for more
radio-quiet cooling neutron stars.


title: Halo Mergers, Galaxy Mergers, and Why Hubble Type Depends on Mass

abstract:
  In the CDM cosmological framework structures grow from merging with smaller
structures. Merging should have observable effects on galaxies including
destroying disks and creating spheroids. This proceeding aims to give a brief
overview of how mergers occur in cosmological simulations. In this regard it is
important to understand that dark matter halo mergers are not galaxy mergers; a
theory of galaxy formation is necessary to connect the two. Mergers of galaxies
in hydrodynamical simulations show a stronger dependence on mass than halo
mergers in N-body simulations. If one knows how to connect galaxies to dark
matter halos then the halo merger rate can be converted into a galaxy merger
rate. When this is done it becomes clear that major mergers are many times more
common in more massive galaxies offering a possible explanation of why Hubble
type depends on galaxy mass.


title:
Factorization of e+e- Event Shape Distributions with Hadronic Final
  States in Soft Collinear Effective Theory

abstract:
  We present a new analysis of two-jet event shape distributions in soft
collinear effective theory. Extending previous results, we observe that a large
class of such distributions can be expressed in terms of vacuum matrix elements
of operators in the effective theory. We match these matrix elements to the
full theory in the two-jet limit without assuming factorization of the complete
set of hadronic final states into independent sums over partonic collinear and
soft states. We also briefly discuss the relationship of this approach to
diagrammatic factorization in the full theory.


title: Viscous, Resistive Magnetorotational Modes

abstract:
  We carry out a comprehensive analysis of the behavior of the
magnetorotational instability (MRI) in viscous, resistive plasmas. We find
exact, non-linear solutions of the non-ideal magnetohydrodynamic (MHD)
equations describing the local dynamics of an incompressible, differentially
rotating background threaded by a vertical magnetic field when disturbances
with wavenumbers perpendicular to the shear are considered. We provide a
geometrical description of these viscous, resistive MRI modes and show how
their physical structure is modified as a function of the Reynolds and magnetic
Reynolds numbers. We demonstrate that when finite dissipative effects are
considered, velocity and magnetic field disturbances are no longer orthogonal
(as it is the case in the ideal MHD limit) unless the magnetic Prandtl number
is unity. We generalize previous results found in the ideal limit and show that
a series of key properties of the mean Reynolds and Maxwell stresses also hold
for the viscous, resistive MRI. In particular, we show that the Reynolds stress
is always positive and the Maxwell stress is always negative. Therefore, even
in the presence of viscosity and resistivity, the total mean angular momentum
transport is always directed outwards. We also find that, for any combination
of the Reynolds and magnetic Reynolds numbers, magnetic disturbances dominate
both the energetics and the transport of angular momentum and that the total
mean energy density is an upper bound for the total mean stress responsible for
angular momentum transport. The ratios between the Maxwell and Reynolds
stresses and between magnetic and kinetic energy densities increase with
decreasing Reynolds numbers for any magnetic Reynolds number; the lowest limit
of both ratios is reached in the ideal MHD regime.


title: Is SP BP?

abstract:
  The Survey Propagation (SP) algorithm for solving $k$-SAT problems has been
shown recently as an instance of the Belief Propagation (BP) algorithm. In this
paper, we show that for general constraint-satisfaction problems, SP may not be
reducible from BP. We also establish the conditions under which such a
reduction is possible. Along our development, we present a unification of the
existing SP algorithms in terms of a probabilistically interpretable iterative
procedure -- weighted Probabilistic Token Passing.


title: The Evolution of Primordial Circumstellar Disks

abstract:
  Circumstellar disks are an integral part of the star formation process and
the sites where planets are formed. Understanding the physical processes that
drive their evolution, as disks evolve from optically thick to optically thin,
is crucial for our understanding of planet formation. Disks evolve through
various processes including accretion onto the star, dust settling and
coagulation, dynamical interactions with forming planets, and
photo-evaporation. However, the relative importance and timescales of these
processes are still poorly understood. In this review, I summarize current
models of the different processes that control the evolution of primordial
circumstellar disks around low-mass stars. I also discuss recent observational
developments on circumstellar disk evolution with a focus on new Spitzer
results on transition objects.


title: How to use magnetic field information for coronal loop identification?

abstract:
  The structure of the solar corona is dominated by the magnetic field because
the magnetic pressure is about four orders of magnitude higher than the plasma
pressure. Due to the high conductivity the emitting coronal plasma (visible
e.g. in SOHO/EIT) outlines the magnetic field lines. The gradient of the
emitting plasma structures is significantly lower parallel to the magnetic
field lines than in the perpendicular direction. Consequently information
regarding the coronal magnetic field can be used for the interpretation of
coronal plasma structures. We extrapolate the coronal magnetic field from
photospheric magnetic field measurements into the corona. The extrapolation
method depends on assumptions regarding coronal currents, e.g. potential fields
(current free) or force-free fields (current parallel to magnetic field). As a
next step we project the reconstructed 3D magnetic field lines on an EIT-image
and compare with the emitting plasma structures. Coronal loops are identified
as closed magnetic field lines with a high emissivity in EIT and a small
gradient of the emissivity along the magnetic field.


title:
On the structure of scattering amplitudes in N=4 super Yang-Mills and
  N=8 supergravity

abstract:
  Exploiting singularities in Feynman integrals to get information about
scattering amplitudes has been particularly useful at one-loop in theories
where no triangles or bubbles appear. At higher loops the integrals possess
subtle singularities. In this paper we give these singularities a physical
interpretation and show how they turn tedious computations into purely
pictorial manipulations. We illustrate our methods with various examples from
the computation of four-particle amplitudes in N=4 super Yang-Mills and N=8
supergravity. Along the way we find clues towards an understanding i) of the
rung-rule as a consequence of infra-red singularities, ii) of the non rung-rule
integrals included in the basis as corrections to the rung-rule and iii) of the
coefficients - including signs - of these two types of contribution. The role
of corrections is to cancel unphysical singularities generically present in
rung-rule integrals. A further byproduct, coming from the fact such unphysical
singularities are located where conformal cross-ratios become unity, is the
possibility of understanding the dual conformal invariance ansatz for
constructing the basis of four-particle amplitudes in N=4 super Yang-Mills.


title:
Analyzing power in elastic scattering of the electrons off a spin-0
  target

abstract:
  We consider the analyzing power on a spin-0 nuclear target. This observable
is related to the imaginary part of the two-photon-exchange (box) diagram. We
consider the contributions of elastic and inelastic intermediate states. The
former requires knowledge of the elastic nuclear form factor, while the latter
uses the optical theorem as input. The elastic contribution scales as the
nuclear charge $Z$, while the inelastic contribution as the ratio of the atomic
number and nuclear charge, $A/Z$. We provide estimates for $^4$He and
$^{208}$Pb, in the kinematics of existing or upcoming experiments. In both
cases, we predict negative values of a few parts per million, and the dominant
contribution is due to inelastic contributions. The analyzing power can
contribute a substantial systematic error in parity-violating experiments.


title: Strong Suppression of Electrical Noise in Bilayer Graphene Nano Devices

abstract:
  Low-frequency 1/f noise is ubiquitous, and dominates the signal-to-noise
performance in nanodevices. Here we investigate the noise characteristics of
single-layer and bilayer graphene nano-devices, and uncover an unexpected 1/f
noise behavior for bilayer devices. Graphene is a single layer of graphite,
where carbon atoms form a 2D honeycomb lattice. Despite the similar
composition, bilayer graphene (two graphene monolayers stacked in the natural
graphite order) is a distinct 2D system with a different band structure and
electrical properties. In graphene monolayers, the 1/f noise is found to follow
Hooge's empirical relation with a noise parameter comparable to that of bulk
semiconductors. However, this 1/f noise is strongly suppressed in bilayer
graphene devices, and exhibits an unusual dependence on the carrier density,
different from most other materials. The unexpected noise behavior in graphene
bilayers is associated with its unique band structure that varies with the
charge distribution among the two layers, resulting in an effective screening
of potential fluctuations due to external impurity charges. The findings here
point to exciting opportunities for graphene bilayers in low-noise
applications.


title:
Monolayer sorption of neon in mesoporous silica glass as monitored by
  WAXS

abstract:
  We report measurements of the x-ray scattering intensity as mesoporous
glasses are filled with Neon. We outline a simple model to account for the
non-linear increase in the intensity of the first peak in a liquid-like
diffraction pattern as a monolayer is formed. This allows us to demonstrate an
approach for surface area determination which does not rely on thermodynamic
models, and is therefore complimentary to existing models.


title: Spitzer Mid-Infrared Spectroscopy of Distant X-ray Luminous AGN

abstract:
  We present mid-infrared spectroscopy of a sample of 16 optically faint
infrared luminous galaxies obtained with the Infrared Spectrograph (IRS) on the
Spitzer Space Telescope. These sources were jointly selected from Spitzer and
Chandra imaging surveys in the NDWFS Bootes field and were selected from their
bright X-ray fluxes to host luminous AGN. None of the spectra show significant
emission from polycyclic aromatic hydrocarbons (PAHs; 6.2um equivalent widths
<0.2um), consistent with their infrared emission being dominated by AGN. Nine
of the X-ray sources show 9.7um silicate absorption features. Their redshifts
are in the range 0.9<z<2.6, implying infrared luminosities of
log(L{IR})=12.5-13.6 solar luminosities. The average silicate absorption
strength is not as strong as that of previously targeted optically faint
infrared luminous galaxies with similar mid-infrared luminosities implying that
the X-ray selection favors sources behind a smaller column of Si-rich dust than
non-X-ray selection. Seven of the X-ray sources have featureless power-law
mid-IR spectra. We argue that the featureless spectra likely result from the
sources having weak or absent silicate and PAH features rather than the sources
lying at higher redshifts where these features are shifted out of the IRS
spectral window. We investigate whether there are any correlations between
X-ray and infrared properties and find that sources with silicate absorption
features tend to have fainter X-ray fluxes and harder X-ray spectra, indicating
a weak relation between the amount of silicate absorption and column density of
X-ray-absorbing gas.


title:
The Josephson relation for the superfluid density in the BCS-BEC
  crossover

abstract:
  The Josephson relation for the superfluid density is derived for a Fermi
superfluid in the BCS-BEC crossover. This identity extends the original
Josephson relation for Bose superfluids. It gives a simple exact relation
between the superfluid density $\rho_s$ and the broken-symmetry Cooper pair
order parameter $\Delta_0$ in terms of the infrared limit of the pair
fluctuation propagator. The same expression holds through the entire BCS-BEC
crossover, describing the superfluid density of a weak-coupling BCS superfluid
as well as the superfluid density of a Bose condensate of dimer molecules.


title: Flux pinning and phase separation in oxygen rich La2-xSrxCuO4+y system

abstract:
  We have studied the magnetic characteristics of a series of super-oxygenated
La2-xSrxCuO4+y samples. As shown in previous work, these samples spontaneously
phase separate into an oxygen rich superconducting phase with a TC near 40 K
and an oxygen poor magnetic phase that also orders near 40 K. All samples
studied are highly magnetically reversible even to low temperatures. Although
the internal magnetic regions of these samples might be expected to act as
pinning sites, our present study shows that they do not favor flux pinning.
Flux pinning requires a matching condition between the defect and the
superconducting coherence length. Thus, our results imply that the magnetic
regions are too large to act as pinning centers. This also implies that the
much greater flux pinning in typical La2-xSrxCuO4 materials is the result of
nanoscale inhomogeneities that grow to become the large magnetic regions in the
super-oxygenated materials. The superconducting regions of the phase separated
materials are in that sense cleaner and more homogenous than in the typical
cuprate superconductor.


title: A proof of the Gordon Conjecture

abstract:
  A combinatorial proof of the Gordon Conjecture: The sum of two Heegaard
splittings is stabilized if and only if one of the two summands is stabilized.


title:
Dynamical CP-Violation: A Supplement to the Kobayashi-Maskawa Matrix in
  the Standard Model

abstract:
  A possible supplementary mechanism of CP-violation to the Kobayashi-Maskawa
theory is considered in the context of dynamical symmetry breaking.


title:
Long Term Evolution of Magnetic Turbulence in Relativistic Collisionless
  Shocks

abstract:
  We study the long term evolution of magnetic fields generated by an initially
unmagnetized collisionless relativistic $e^+e^-$ shock. Our 2D particle-in-cell
numerical simulations show that downstream of such a Weibel-mediated shock,
particle distributions are approximately isotropic, relativistic Maxwellians,
and the magnetic turbulence is highly intermittent spatially, nonpropagating,
and decaying. Using linear kinetic theory, we find a simple analytic form for
these damping rates. Our theory predicts that overall magnetic energy decays
like $(\omega_p t)^{-q}$ with $q \sim 1$, which compares favorably with
simulations, but predicts overly rapid damping of short wavelength modes.
Magnetic trapping of particles within the magnetic structures may be the origin
of this discrepancy. We conclude that initially unmagnetized relativistic
shocks in electron-positron plasmas are unable to form persistent downstream
magnetic fields. These results put interesting constraints on synchrotron
models for the prompt and afterglow emission from GRBs.


title: Midisuperspace Supersymmetric Quantum Cosmology

abstract:
  We investigate the canonical quantization in the framework of N=1 simple
supergravity for the case of a very simple gravitational midisuperspace
described by Gowdy $T^3$ cosmological models. We consider supersymmetric
quantum cosmology in the mentioned midisuperspace, where a matrix
representation for the gravitino covector--spinor is used. The full Lorentz
constraint and its implications for the wave function of the universe are
analyzed in detail. We found that there are indeed physical states in the
midisuperspace sector of the theory in contrast to the case of minisuperspace
where there exist no physical states.


title: The Complexity of Power-Index Comparison

abstract:
  We study the complexity of the following problem: Given two weighted voting
games G' and G'' that each contain a player p, in which of these games is p's
power index value higher? We study this problem with respect to both the
Shapley-Shubik power index [SS54] and the Banzhaf power index [Ban65,DS79]. Our
main result is that for both of these power indices the problem is complete for
probabilistic polynomial time (i.e., is PP-complete). We apply our results to
partially resolve some recently proposed problems regarding the complexity of
weighted voting games. We also study the complexity of the raw Shapley-Shubik
power index. Deng and Papadimitriou [DP94] showed that the raw Shapley-Shubik
power index is #P-metric-complete. We strengthen this by showing that the raw
Shapley-Shubik power index is many-one complete for #P. And our strengthening
cannot possibly be further improved to parsimonious completeness, since we
observe that, in contrast with the raw Banzhaf power index, the raw
Shapley-Shubik power index is not #P-parsimonious-complete.


title: C_2 in Peculiar DQ White Dwarfs

abstract:
  White dwarfs (WDs) with carbon absorption features in their optical spectra
are known as DQ WDs. The subclass of peculiar DQ WDs are cool objects
(T_eff<6000 K) which show molecular absorption bands that have centroid
wavelengths ~100-300 Angstroms shortward of the bandheads of the C_2 Swan
bands. These "peculiar DQ bands" have been attributed to a hydrocarbon such as
C_2H. We point out that C_2H does not show strong absorption bands with
wavelengths matching those of the peculiar DQ bands and neither does any other
simple molecule or ion likely to be present in a cool WD atmosphere. The most
straightforward explanation for the peculiar DQ bands is that they are
pressure-shifted Swan bands of C_2. While current models of WD atmospheres
suggest that, in general, peculiar DQ WDs do not have higher photospheric
pressures than normal DQ WDs do, that finding requires confirmation by improved
models of WD atmospheres and of the behavior of C_2 at high pressures and
temperatures. If it is eventually shown that the peculiar DQ bands cannot be
explained as pressure-shifted Swan bands, the only explanation remaining would
seem to be that they arise from highly rotationally excited C_2 (J_peak>45). In
either case, the absorption band profiles can in principle be used to constrain
the pressure and the rotational temperature of C_2 in the line-forming regions
of normal and peculiar DQ WD atmospheres, which will be useful for comparison
with models. Finally, we note that progress in understanding magnetic DQ WDs
may require models which simultaneously consider magnetic fields, high
pressures and rotational excitation of C_2.


title: Twistorial maps between quaternionic manifolds

abstract:
  We introduce a natural notion of quaternionic map between almost quaternionic
manifolds and we prove the following, for maps of rank at least one: 1) A map
between quaternionic manifolds endowed with the integrable almost twistorial
structures is twistorial if and only if it is quaternionic. 2) A map between
quaternionic manifolds endowed with the nonintegrable almost twistorial
structures is twistorial if and only if it is quaternionic and
totally-geodesic. As an application, we describe the quaternionic maps between
open sets of quaternionic projective spaces.


title:
Edge states and the integer quantum Hall effect of spin-chiral
  ferromagnetic kagome lattice with a general spin coupling

abstract:
  The chiral edge states and the quantized Hall conductance (QHC) in the
two-dimensional kagom\'{e} lattice with spin anisotropies included in a general
Hund's coupling region are studied. This kagom\'{e} lattice system is periodic
in the $x$ direction but has two edges in the $y$ direction. Numerical results
show that the strength of the Hund's coupling, as well as the spin chirality,
affects the edge states and the corresponding QHC. Within the topological edge
theory, we give the expression of the QHC with the winding number of the chiral
edge states on the Riemman surface. This expression is also compaired with that
within the topological bulk theory and they are found to keep consistent with
each other.


title: Precision Measurement of Neutrino Oscillation Parameters with KamLAND

abstract:
  The KamLAND experiment has determined a precise value for the neutrino
oscillation parameter $\Delta m^{2}_{21}$ and stringent constraints on
$\theta_{12}$. The exposure to nuclear reactor anti-neutrinos is increased
almost fourfold over previous results to 2.44$\times10^{32}$ proton-yr due to
longer livetime and an enlarged fiducial volume. An undistorted reactor
$\bar{\nu}_{e}$ energy spectrum is now rejected at >5$\sigma$. Extending the
analysis down to the inverse beta decay energy threshold, and incorporating
geo-neutrinos, gives a best-fit at $\Delta m^{2}_{21}$=
$7.58^{+0.14}_{-0.13}(stat)^{+0.15}_{-0.15}(syst)\times10^{-5}$ eV$^{2}$ and
$\tan^2 \theta_{12}$=$0.56^{+0.10}_{0.07}(stat)^{+0.10}_{-0.06}(syst)$. Local
$\Delta \chi^2$-minima at higher and lower $\Delta m^{2}_{21}$ are disfavored
at >4$\sigma$. Combining with solar neutrino data, we obtain $\Delta
m^{2}_{21}$= $7.59^{+0.21}_{-0.21}\times10^{-5}$ eV$^{2}$ and $\tan^2
\theta_{12}$=$0.47^{+0.06}_{-0.05}$.


title: Counting lattice points in the moduli space of curves

abstract:
  We show how to define and count lattice points in the moduli space
$\modm_{g,n}$ of genus g curves with n labeled points. This produces a
polynomial with coefficients that include the Euler characteristic of the
moduli space, and tautological intersection numbers on the compactified moduli
space.


title: de Sitter Thermodynamics: A glimpse into non equilibrium

abstract:
  In this article is shown that the thermodynamical evolution of a
Schwarzschild de Sitter space is the evaporation of its black hole. The result
is extended in higher dimensions to Lovelock theories of gravity with a single
positive cosmological constant.


title:
Understanding the Paradoxical Effects of Power Control on the Capacity
  of Wireless Networks

abstract:
  Recent works show conflicting results: network capacity may increase or
decrease with higher transmission power under different scenarios. In this
work, we want to understand this paradox. Specifically, we address the
following questions: (1)Theoretically, should we increase or decrease
transmission power to maximize network capacity? (2) Theoretically, how much
network capacity gain can we achieve by power control? (3) Under realistic
situations, how do power control, link scheduling and routing interact with
each other? Under which scenarios can we expect a large capacity gain by using
higher transmission power? To answer these questions, firstly, we prove that
the optimal network capacity is a non-decreasing function of transmission
power. Secondly, we prove that the optimal network capacity can be increased
unlimitedly by higher transmission power in some network configurations.
However, when nodes are distributed uniformly, the gain of optimal network
capacity by higher transmission power is upper-bounded by a positive constant.
Thirdly, we discuss why network capacity in practice may increase or decrease
with higher transmission power under different scenarios using carrier sensing
and the minimum hop-count routing. Extensive simulations are carried out to
verify our analysis.


title: Characteristic varieties for a class of line arrangements

abstract:
  Let $\mathcal{A}$ be a line arrangement in the complex projective plane
$\mathbb{P}^2$, having the points of multiplicity $\geq 3$ situated on two
lines in $\mathcal{A}$, say $H_0$ and $H_{\infty}$. Then we show that the
non-local irreducible components of the first resonance variety
$\mathcal{R}_1(\mathcal{A})$ are 2-dimensional and correspond to parallelograms
$\mathcal{P}$ in $\mathbb{C}^2=\mathbb{P}^2 \setminus H_{\infty}$ whose sides
are in $\mathcal{A}$ and for which $H_0$ is a diagonal.


title: Lightlike Wilson loops from AdS/CFT

abstract:
  We investigate the lightlike limit of stationary spacelike string
configurations on a large class of five-dimensional asymptotically AdS
backgrounds. Specific examples include gravity duals which incorporate finite
't Hooft coupling, curvature-squared corrections, and chemical potentials. A
universal feature of these AdS/CFT models is that the string solution with
minimum action yields a lightlike Wilson loop whose leading behavior is
exponentially linear, rather than quadratic, in the width of the loop. Unless
there is a compelling reason for discarding the leading saddlepoint
contribution to the Wilson loop, following the proposal of Liu et. al. [2]
leads to zero jet-quenching parameter for all of these models.


title: Interference enhancement of Raman signal of graphene

abstract:
  Raman spectroscopic studies of graphene have attracted much interest. The
G-band Raman intensity of a single layer graphene on Si substrate with 300 nm
SiO2 capping layer is surprisingly strong and is comparable to that of bulk
graphite. To explain this Raman intensity anomaly, we show that in addition to
the interference due to multiple reflection of the incident laser, the multiple
reflection of the Raman signal inside the graphene layer must be also accounted
for. Further studies of the role of SiO2 layer in the enhancement Raman signal
of graphene are carried out and an enhancement factor of ~30 is achievable,
which is very significant for the Raman studies. Finally, we discuss the
potential application of this enhancement effect on other ultra-thin films and
nanoflakes and a general selection criterion of capping layer and substrate is
given.


title: Relative hyperbolicity and relative quasiconvexity for countable groups

abstract:
  We lay the foundations for the study of relatively quasiconvex subgroups of
relatively hyperbolic groups. These foundations require that we first work out
a coherent theory of countable relatively hyperbolic groups (not necessarily
finitely generated). We prove the equivalence of Gromov, Osin, and Bowditch's
definitions of relative hyperbolicity for countable groups.
  We then give several equivalent definitions of relatively quasiconvex
subgroups in terms of various natural geometries on a relatively hyperbolic
group. We show that each relatively quasiconvex subgroup is itself relatively
hyperbolic, and that the intersection of two relatively quasiconvex subgroups
is again relatively quasiconvex. In the finitely generated case, we prove that
every undistorted subgroup is relatively quasiconvex, and we compute the
distortion of a finitely generated relatively quasiconvex subgroup.


title: C$^{*}$-bialgebra defined by the direct sum of Cuntz-Krieger algebras

abstract:
  Let ${\sf CK}_{*}$ denote the C$^{*}$-algebra defined by the direct sum of
all Cuntz-Krieger algebras. We introduce a comultiplication $\Delta_{\phi}$ and
a counit $\epsilon$ on ${\sf CK}_{*}$ such that $\Delta_{\phi}$ is a
nondegenerate $*$-homomorphism from ${\sf CK}_{*}$ to ${\sf CK}_{*}\otimes {\sf
CK}_{*}$ and $\epsilon$ is a $*$-homomorphism from ${\sf CK}_{*}$ to ${\bf C}$.
From this, ${\sf CK}_{*}$ is a counital non-commutative non-cocommutative
C$^{*}$-bialgebra. Furthermore, C$^{*}$-bialgebra automorphisms, a tensor
product of representations and C$^{*}$-subbialgebras of ${\sf CK}_{*}$ are
investigated.


title: Stimulated emission of surface plasmon polaritons

abstract:
  We have observed laser-like emission of surface plasmon polaritons (SPPs)
decoupled to the glass prism in an attenuated total reflection setup. SPPs were
excited by optically pumped molecules in a polymeric film deposited on the top
of the silver film. Stimulated emission was characterized by a distinct
threshold in the input-output dependence and narrowing of the emission
spectrum. The observed stimulated emission and corresponding to it compensation
of the metallic absorption loss by gain enables many applications of
metamaterials and nanoplasmonic devices.


title: Modeling an efficient Brownian heat engine

abstract:
  We discuss the effect of subdividing the ratchet potential on the performance
of a tiny Brownian heat engine that is modeled as a Brownian particle hopping
in a viscous medium in a sawtooth potential (with or without load) assisted by
alternately placed hot and cold heat baths along its path. We show that the
velocity, the efficiency and the coefficient of performance of the refrigerator
maximize when the sawtooth potential is subdivided into series of smaller
connected barrier series. When the engine operates quasistatically, we
analytically show that the efficiency of the engine can not approach the Carnot
efficiency and, the coefficient of performance of the refrigerator is always
less than the Carnot refrigerator due to the irreversible heat flow via the
kinetic energy.


title:
Neutron-proton analyzing power at 12 MeV and inconsistencies in
  parametrizations of nucleon-nucleon data

abstract:
  We present the most accurate and complete data set for the analyzing power
Ay(theta) in neutron-proton scattering. The experimental data were corrected
for the effects of multiple scattering, both in the center detector and in the
neutron detectors. The final data at En = 12.0 MeV deviate considerably from
the predictions of nucleon-nucleon phase-shift analyses and potential models.
The impact of the new data on the value of the charged pion-nucleon coupling
constant is discussed in a model study.


title:
The physical structure of the point-symmetric and quadrupolar planetary
  nebula NGC 6309

abstract:
  We analyse the point-symmetric planetary nebula NGC 6309 in terms of its
three-dimensional structure and of internal variations of the physical
conditions to deduce the physical processes involved in its formation. We used
VLA-D 3.6-cm continuum, ground-based, and HST-archive imaging as well as long
slit high- and low-dispersion spectroscopy. The low-dispersion spectra indicate
a high excitation nebula, with low to medium variations of its internal
physical conditions. In the optical images, the point-symmetric knots show a
lack of [NII] emission as compared with similar features previously known in
other PNe. A rich internal structure of the central region is seen in the HST
images, resembling a deformed torus. Long slit high-dispersion spectra reveal a
complex kinematics in the central region. The spectral line profiles from the
external regions of NGC 6309 indicate expanding lobes (~40 km/s) as those
generally found in bipolar nebulae. Finally, we have found evidence for the
presence of a faint halo, possibly related to the envelope of the AGB-star
progenitor. Our data indicate that NGC 6309 is a quadrupolar nebula with two
pairs of bipolar lobes whose axes are oriented PA=40 and PA=76. Equatorial and
polar velocities for these two pairs of lobes are 29 and 86 km/s for the
bipolar system at PA=40 and 25 and 75 km/s for the bipolar system at PA=76.
There is also a central torus that is expanding at 25 km/s. Kinematical age for
all these structures is around 3700 to 4000 yr. We conclude that NGC 6309 was
formed by a set of well-collimated bipolar outflows (jets), which were ejected
in the initial stages of its formation as a planetary nebula. These jets carved
the bipolar lobes in the previous AGB wind and their remnants are now observed
as the point-symmetric knots tracing the edges of the lobes.


title: Collective states of interacting Fibonacci anyons

abstract:
  We show that chains of interacting Fibonacci anyons can support a wide
variety of collective ground states ranging from extended critical, gapless
phases to gapped phases with ground-state degeneracy and quasiparticle
excitations. In particular, we generalize the Majumdar-Ghosh Hamiltonian to
anyonic degrees of freedom by extending recently studied pairwise anyonic
interactions to three-anyon exchanges. The energetic competition between two-
and three-anyon interactions leads to a rich phase diagram that harbors
multiple critical and gapped phases. For the critical phases and their higher
symmetry endpoints we numerically establish descriptions in terms of
two-dimensional conformal field theories. A topological symmetry protects the
critical phases and determines the nature of gapped phases.


title: The Y(2175) State in the QCD Sum Rule

abstract:
  We study the mass of the state Y(2175) of J^{PC} = 1^{--} in the QCD sum
rule. We construct both the diquark-antidiquark currents (ss)(s_bar s_bar) and
the meson-meson currents (s_bar s)(s_bar s). We find that there are two
independent currents for both cases, and derive the relations between them. The
OPE convergence of these two currents is sufficiently fast, which enables us to
perform good sum rule analysis. Both the SVZ sum rule and the finite energy sum
rule lead to a mass around 2.3+-0.4 GeV, which is consistent with the observed
mass within the uncertainties of the present QCD sum rule. The coupling of the
four-quark currents to lower lying states such as \phi(1020) turns out to be
rather small. We also discuss possible decay properties of Y(2175) if it is a
tetraquark state.


title: Quantum information with Gaussian states

abstract:
  Quantum optical Gaussian states are a type of important robust quantum states
which are manipulatable by the existing technologies. So far, most of the
important quantum information experiments are done with such states, including
bright Gaussian light and weak Gaussian light. Extending the existing results
of quantum information with discrete quantum states to the case of continuous
variable quantum states is an interesting theoretical job. The quantum Gaussian
states play a central role in such a case. We review the properties and
applications of Gaussian states in quantum information with emphasis on the
fundamental concepts, the calculation techniques and the effects of
imperfections of the real-life experimental setups.
  Topics here include the elementary properties of Gaussian states and relevant
quantum information device, entanglement-based quantum tasks such as quantum
teleportation, quantum cryptography with weak and strong Gaussian states and
the quantum channel capacity, mathematical theory of quantum entanglement and
state estimation for Gaussian states.


title:
Twisted cyclic theory and an index theory for the gauge invariant KMS
  state on Cuntz algebras

abstract:
  This paper presents, by example, an index theory appropriate to algebras
without trace. Whilst we work exclusively with the Cuntz algebras the
exposition is designed to indicate how to develop a general theory. Our main
result is an index theorem (formulated in terms of spectral flow) using a
twisted cyclic cocycle where the twisting comes from the modular automorphism
group for the canonical gauge action on the Cuntz algebra. We introduce a
modified $K_1$-group of the Cuntz algebra so as to pair with this twisted
cocycle. As a corollary we obtain a noncommutative geometry interpretation for
Araki's notion of relative entropy in this example. We also note the connection
of this example to the theory of noncommutative manifolds.


title: Palatini f(R) Cosmology

abstract:
  We investigate the modified gravity theories in terms of the effective dark
energy models. We compare the cosmic expansion history and the linear growth in
different models. We also study the evolution of linear cosmological
perturbations in modified theories of gravity assuming the Palatini formalism.
We find the stability of the superhorizon metric evolution depends on models.
We also study the matter density fluctuation in the general gauge and show the
differential equations in super and sub-horizon scales.


title: Quotients by non-reductive algebraic group actions

abstract:
  Given a suitable action on a complex projective variety X of a non-reductive
affine algebraic group H, this paper considers how to choose a reductive group
G containing H and a projective completion of G x_H X which is a reductive
envelope in the sense of math.AG/0703131. In particular it studies the family
of examples given by moduli spaces of hypersurfaces in the weighted projective
plane P(1,1,2) obtained as quotients by linear actions of the (non-reductive)
automorphism group of P(1,1,2).


title: Finsleroid-regular space. Landsberg-to-Berwald implication

abstract:
  By performing required evaluations, we show that in the Finsleroid-regular
space the Landsberg-space condition just degenerates to the Berwald-space
condition (at any dimension number $N\ge2$). Simple and clear expository
representations are obtained. Due comparisons with the Finsleroid-Finsler space
are indicated.
  Keywords: Finsler metrics, spray coefficients, curvature tensors.


title:
Un scindage de l'application de Frobenius sur toute l'alg\`ebre des
  distributions de SL_2

abstract:
  We study a splitting of the Frobenius map on the whole algebra of
distributions of SL_2 (over a finite field) and its relation with the explicit
Frobenius descent on arithmetic D-modules over the projective line


title:
Sup-norm convergence rate and sign concentration property of Lasso and
  Dantzig estimators

abstract:
  We derive the $l_{\infty}$ convergence rate simultaneously for Lasso and
Dantzig estimators in a high-dimensional linear regression model under a mutual
coherence assumption on the Gram matrix of the design and two different
assumptions on the noise: Gaussian noise and general noise with finite
variance. Then we prove that simultaneously the thresholded Lasso and Dantzig
estimators with a proper choice of the threshold enjoy a sign concentration
property provided that the non-zero components of the target vector are not too
small.


title: Effective theory of fluctuating circulating currents in high-Tc cuprates

abstract:
  We derive an effective dissipative quantum field theory for fluctuating
orbital currents in clean $CuO_2$ sheets of high-$T_c$ cuprates, based on a
three-band model. The Coulomb repulsion term between $Cu$- and $O$-sites is
decoupled in terms of current operators representing horizontal and vertical
parts of circulating currents within each $CuO_2$ unit cell of the lattice. The
model has ordering of currents at finite temperatures. The dissipative kernel
in the model is of the form $|\omega|/|{\bf q}|$, indicating Landau damping.
Applications of the effective theory to other models are also discussed.


title: HST Snapshot Survey of Post-AGB Objects

abstract:
  The results from a Hubble Space Telescope (HST) snapshot survey of post-AGB
objects are shown. The aim of the survey is to complement existing HST images
of PPN and to connect various types of nebulosities with physical and chemical
properties of their central stars. Nebulosities are detected in 15 of 33
sources. Images and photometric and geometric measurements are presented. For
sources with nebulosities we see a morphological bifurcation into two groups,
DUPLEX and SOLE, as previous studies have found. We find further support to the
previous results suggesting that this dichotomy is caused by a difference in
optical thickness of the dust shell. The remaining 18 sources are classified as
stellar post-AGB objects, because our observations indicate a lack of
nebulosity. We show that some stellar sources may in fact be DUPLEX or SOLE
based on their infrared colors. The cause of the differences among the groups
are investigated. We discuss some evidence suggesting that high progenitor-mass
AGB stars tend to become DUPLEX post-AGB objects. Intermediate progenitor-mass
AGB stars tend to be SOLE post-AGB objects. Most of the stellar sources
probably have low mass progenitors and do not seem to develop nebulosities
during the post-AGB phase and therefore do not become planetary nebulae.


title:
X-ray Emissions from Three-dimensional Magnetohydrodynamic Coronal
  Accretion Flows

abstract:
  We calculate the radiation spectrum and its time variability of the black
hole accretion disk-corona system based on the three-dimensional
magnetohydrodynamic simulation. In explaining the spectral properties of active
galactic nuclei (AGNs), it is often assumed that they consist of a
geometrically thin, optically thick disk and hot, optically thin corona
surrounding the thin disk. As for a model of the corona, we adopt the
simulation data of three-dimensional, non-radiative MHD accretion flows
calculated by Kato and coworkers, while for a thin disk we assume a standard
type disk. We perform Monte Carlo radiative transfer simulations in the corona,
taking into account the Compton scattering of soft photons from the thin disk
by hot thermal electrons and coronal irradiation heating of the thin disk,
which emits blackbody radiation. By adjusting the density parameter of the MHD
coronal flow, we can produce the emergent spectra which are consistent with
those of typical Seyfert galaxies. Moreover, we find rapid time variability in
X-ray emission spectra, originating from the density fluctuation produced by
the magnetorotational instability in the MHD corona. The features of reflection
component including iron fluorescent line emission are also briefly discussed.


title:
Nonisomorphic curves that become isomorphic over extensions of coprime
  degrees

abstract:
  We show that one can find two nonisomorphic curves over a field K that become
isomorphic to one another over two finite extensions of K whose degrees over K
are coprime to one another.
  More specifically, let K_0 be an arbitrary prime field and let r and s be
integers greater than 1 that are coprime to one another. We show that one can
find a finite extension K of K_0, a degree-r extension L of K, a degree-s
extension M of K, and two curves C and D over K such that C and D become
isomorphic to one another over L and over M, but not over any proper
subextensions of L/K or M/K.
  We show that such C and D can never have genus 0, and that if K is finite, C
and D can have genus 1 if and only if {r,s} = {2,3} and K is an odd-degree
extension of F_3. On the other hand, when {r,s}={2,3} we show that genus-2
examples occur in every characteristic other than 3.
  Our detailed analysis of the case {r,s} = {2,3} shows that over every finite
field K there exist nonisomorphic curves C and D that become isomorphic to one
another over the quadratic and cubic extensions of K.
  Most of our proofs rely on Galois cohomology. Without using Galois
cohomology, we show that two nonisomorphic genus-0 curves over an arbitrary
field remain nonisomorphic over every odd-degree extension of the base field.


title:
The circular loop equation of a cosmic string with time-varying tension
  in de Sitter spacetimes

abstract:
  In this work the equation of circular loops of cosmic string possessing
time-dependent tension is studied in the de Sitter spacetime. We find that the
cosmic string loops with initial radius $r(t_{0})>0.707L$, L de Sitter radius,
should not collapse to form a black holes. It is also found that in the case of
$r(t_{0})<0.707L$ a loop of cosmic string whose tension depends on some power
of cosmic time can not become a black hole if the power is lower than a
critical value which is associated with the initial size of the loop.


title:
Continuous and measurable eigenfunctions of linearly recurrent dynamical
  Cantor systems

abstract:
  The class of linearly recurrent Cantor systems contains the substitution
subshifts and some odometers. For substitution subshifts and odometers
measure--theoretical and continuous eigenvalues are the same. It is natural to
ask whether this rigidity property remains true for the class of linearly
recurrent Cantor systems. We give partial answers to this question.


title:
Universal quantum computation with quantum-dot cellular automata in
  dephasing-free subspace

abstract:
  We investigate the possibility to have electron-pairs in dephasing-free
subspace (DFS), by means of the quantum-dot cellular automata (QCA) and
single-spin rotations, to carry out a high-fidelity and deterministic universal
quantum computation. We show that our QCA device with electrons tunneling two
dimensionally is very suitable for DFS encoding, and argue that our design
favors a scalable quantum computation robust to collective dephasing errors.


title: Multi-wavelength surveys towards the SKA pathfinders

abstract:
  In these proceedings I discuss various extragalactic surveys which will be
undertaken over the next few years and which will be complementary to any HI
and/or continuum surveys with the SKA-pathfinder telescopes. I concentrate on
the near-infrared public surveys which will be undertaken with the Visible and
Infrared Survey Telscope for Astronomy (VISTA), and in particular the VISTA
Deep Extragalactic Observations (VIDEO) survey which will provide the ideal
data set to combine with any deep SKA-pathfinder observations of the
extragalactic sky. After highlighting the links that the SKA pathfinders have
with the various VISTA surveys, I briefly describe an approved large area
survey to be carried out with the Herschel Space Observatory which has a large
scientific overlap with the SKA pathfinder telescopes.


title:
Necessary and sufficient conditions to be an eigenvalue for linearly
  recurrent dynamical Cantor systems

abstract:
  We give necessary and sufficient conditions to have measurable and continuous
eigenfunctions for linearly recurrent Cantor dynamical systems. We also
construct explicitly an example of linearly recurrent system with nontrivial
Kronecker factor and a trivial maximal equicontinuous factor.


title: Comment on "Anyonic braiding in optical lattices"

abstract:
  We point out some major technical and conceptual mistakes which invalidate
the conclusion drawn in "Anyonic braiding in optical lattices" by C. Zhang, V.
W. Scarola, S. Tewari, and S. Das Sarma published in PNAS 104, 18415 (2007).


title: Convex ordering for random vectors using predictable representation

abstract:
  We prove convex ordering results for random vectors admitting a predictable
representation in terms of a Brownian motion and a non-necessarily independent
jump component. Our method uses forward-backward stochastic calculus and
extends previous results in the one-dimensional case. We also study a geometric
interpretation of convex ordering for discrete measures in connection with the
conditions set on the jump heights and intensities of the considered processes.


title: Boltzmann bias grand canonical Monte Carlo

abstract:
  We derive an efficient method for the insertion of structured particles in
grand canonical Monte Carlo simulations of adsorption in very confining
geometries. We extend this method to path integral simulations and use it to
calculate the isotherm of adsorption of hydrogen isotopes in narrow carbon
nanotubes (2D confinement) and slit pores (1D confinement) at the temperatures
of 20 K and 77 K, discussing its efficiency by comparison to the standard path
integral grand canonical Monte Carlo algorithm. We use this algorithm to
perform multicomponent simulations in order to calculate the hydrogen isotope
selectivity for adsorption in narrow carbon nanotubes and slit pores at finite
pressures. The algorithm described here can be applied to the study of
adsorption of real oligomers and polymers in narrow pores and channels.


title: Passage of small black hole through the Earth. Is it detectable?

abstract:
  We examine the energy losses of a small black hole passing through the Earth,
and in particular, the excitations created in the frequency range accessible to
modern acoustic detectors. The dominating contributions to the effect are due
to the coherent sound radiation of the Cherenkov type and to the conversion of
black hole radiation into sound waves.


title: Optimal regularity for planar mappings of finite distortion

abstract:
  Let $f:\Omega\to\IR^2$ be a mapping of finite distortion, where
$\Omega\subset\IR^2 .$ Assume that the distortion function $K(x,f)$ satisfies
$e^{K(\cdot, f)}\in L^p_{loc}(\Omega)$ for some $p>0.$ We establish optimal
regularity and area distortion estimates for $f$. Especially, we prove that
$|Df|^2 \log^{\beta -1}(e + |Df|) \in L^1_{loc}(\Omega) $ for every $\beta <p.$
This answers positively well known conjectures due to Iwaniec and Martin
\cite{IMbook} and to Iwaniec, Koskela and Martin \cite{IKM}.


title:
Thermally activated charge carriers and mid-infrared optical excitations
  in quarter-filled CDW systems

abstract:
  The optical properties of the quarter-filled single-band CDW systems have
been reexamined in the model with the electron-phonon coupling related to the
variations of electron site energies. It appears that the indirect,
electron-mediated coupling between phase phonons and external electromagnetic
fields vanishes for symmetry reasons, at variance with the infrared selection
rules used in the generally accepted microscopic theory. It is shown that the
phase phonon modes and the electric fields couple directly, with the coupling
constant proportional to the magnitude of the charge-density wave. The
single-particle contributions to the optical conductivity tensor are determined
for the ordered CDW state and the related weakly doped metallic state by means
of the Bethe--Salpeter equations for elementary electron-hole excitations. It
turns out that this gauge-invariant approach establishes a clear connection
between the effective numbers of residual, thermally activated and bound charge
carriers. Finally, the relation between these numbers and the activation energy
of dc conductivity and the optical CDW gap scale is explained in the way
consistent with the conductivity sum rules.


title: Limited local electron-lattice coupling in manganites

abstract:
  (Pr,Ca)MnO3 is the archetypal charge-ordered manganite, but in
Pr0.48Ca0.52MnO3 we find (using convergent-beam electron diffraction and
dark-field images) that the superlattice period is locally incommensurate with
respect to the parent lattice, and that the superlattice orientation possesses
significant local variations. This suggests that local electron-lattice
coupling never overwhelmingly dominates the rich physics of manganites, even in
the most extreme scenarios that produce the largest colossal magnetoresistance
effects.


title: On the Distribution of the Adaptive LASSO Estimator

abstract:
  We study the distribution of the adaptive LASSO estimator (Zou (2006)) in
finite samples as well as in the large-sample limit. The large-sample
distributions are derived both for the case where the adaptive LASSO estimator
is tuned to perform conservative model selection as well as for the case where
the tuning results in consistent model selection. We show that the
finite-sample as well as the large-sample distributions are typically highly
non-normal, regardless of the choice of the tuning parameter. The uniform
convergence rate is also obtained, and is shown to be slower than $n^{-1/2}$ in
case the estimator is tuned to perform consistent model selection. In
particular, these results question the statistical relevance of the `oracle'
property of the adaptive LASSO estimator established in Zou (2006). Moreover,
we also provide an impossibility result regarding the estimation of the
distribution function of the adaptive LASSO estimator.The theoretical results,
which are obtained for a regression model with orthogonal design, are
complemented by a Monte Carlo study using non-orthogonal regressors.


title: Transversality and Lefschetz numbers for foliation maps

abstract:
  Let $F$ be a smooth foliation on a closed Riemannian manifold $M$, and let
$\Lambda$ be a transverse invariant measure of $F$. Suppose that $\Lambda$ is
absolutely continuous with respect to the Lebesgue measure on smooth
transversals. Then a topological definition of the $\Lambda$-Lefschetz number
of any leaf preserving diffeomorphism $(M,F)\to(M,F)$ is given. For this
purpose, standard results about smooth approximation and transversality are
extended to the case of foliation maps. It is asked whether this topological
$\Lambda$-Lefschetz number is equal to the analytic $\Lambda$-Lefschetz number
defined by Heitsch and Lazarov which would be a version of the Lefschetz trace
formula. Heitsch and Lazarov have shown such a trace formula when the fixed
point set is transverse to $F$.


title: Recursive Bias Estimation and $L_2$ Boosting

abstract:
  This paper presents a general iterative bias correction procedure for
regression smoothers. This bias reduction schema is shown to correspond
operationally to the $L_2$ Boosting algorithm and provides a new statistical
interpretation for $L_2$ Boosting. We analyze the behavior of the Boosting
algorithm applied to common smoothers $S$ which we show depend on the spectrum
of $I-S$. We present examples of common smoother for which Boosting generates a
divergent sequence. The statistical interpretation suggest combining algorithm
with an appropriate stopping rule for the iterative procedure. Finally we
illustrate the practical finite sample performances of the iterative smoother
via a simulation study. simulations.


title: Regular patterns in the acoustic spectrum of rapidly rotating stars

abstract:
  Context: Rapid rotation modifies the structure of the frequency spectrum of
pulsating stars, thus making mode identification difficult.
  Aims: We look for new forms of organisation for the frequency spectrum that
can provide a basis for mode identification at high rotation rates.
  Methods: Acoustic modes in uniformly rotating polytropic models of stars are
computed using a numerical code that fully takes the effects of rotation
(centrifugal distortion and Coriolis acceleration) into account. All low-degree
modes, l=0 to 3, with radial orders n=1-10 and 21-25 for N=3 polytropic models
and n=1-10 for N=1.5 polytropic models are followed from a zero rotation rate
up to 59 % of the break-up velocity.
  Results: We find an empirical formula that gives a good description of the
high-frequency range of the computed acoustic spectrum for high rotation rates.
Differences between this formula and complete eigenmode calculations are shown
to be substantially smaller than those obtained with a third order perturbative
method valid at low rotation rates.


title: Collective effects in central heavy-ion collisions

abstract:
  In-medium effects on transverse-mass distributions of quarks and gluons are
considered assuming a possible local equilibrium for colorless quark objects
(mesons and baryons) created in central A-A collisions. It is shown that the
average transverse momentum squared for these partons grows and then saturates
when the initial energy increases. Within the quark-gluon string model it leads
to the colliding energy dependence of hadron transverse mass spectra which is
similar to that observed in heavy ion collisions. Comparison with other
scenarios is given.


title:
On the scaling of probability density functions with apparent power-law
  exponents less than unity

abstract:
  We derive general properties of the finite-size scaling of probability
density functions and show that when the apparent exponent \tautilde of a
probability density is less than 1, the associated finite-size scaling ansatz
has a scaling exponent \tau equal to 1, provided that the fraction of events in
the universal scaling part of the probability density function is non-vanishing
in the thermodynamic limit. We find the general result that \tau>=1 and
\tau>=\tautilde. Moreover, we show that if the scaling function G(x) approaches
a non-zero constant for small arguments, \lim_{x-> 0} G(x) > 0, then
\tau=\tautilde. However, if the scaling function vanishes for small arguments,
\lim_{x-> 0} G(x) = 0, then \tau=1, again assuming a non-vanishing fraction of
universal events. Finally, we apply the formalism developed to examples from
the literature, including some where misunderstandings of the theory of scaling
have led to erroneous conclusions.


title: Spin waves in disordered magnetic systems

abstract:
  Long-wavelength spin waves in disordered magnetic systems have been
investigated. In the framework of the Heisenberg model with magnetic dipole and
exchange interactions between spins it is found that an additional longitudinal
spin wave mode appears. This mode is characterized by variations of the value
of the magnetic moment density. In order to analyse influence of the magnetic
disorder on spin wave dispersion relations, the special case of volume and
surface spin waves in the Damon-Eshbach (DE) geometry in films with magnetic
disorder is considered. It is revealed strong influence of the magnetic
disorder on surface spin waves, which consist of two branches -- the DE mode
and the longitudinal spin wave mode. Decrease of the ordering parameters leads
to a decrease of the initial frequency and the curve slope of the DE mode
dispersion curve and to an increase of the dispersion curve slope of the
longitudinal mode. If the spin noncollinearity is high, then the DE mode
dispersion assumes a curve with the backward character. It is found that the
dispersion relation of the longitudinal mode is weak temperature dependent. The
developed model can explain the observed double-peak structure of FMR spectra
in magnetic nanocomposites.


title: The diagonal cosets of the Heisenberg group

abstract:
  In this paper we study the diagonal cosets of the non-compact H4 WZW model.
Generalising earlier work by Antoniadis and Obers, we provide an exact
world-sheet description for several families of non-maximally symmetric
gravitational plane waves with background NS fluxes. We show that the
sigma-models that correspond to an asymmetric action of the gauge group
smoothly interpolate between singular and non-singular plane waves. We also
analyse the representations of the coset chiral algebra and derive the spectrum
of all the models.


title: (2+3) dimensional geometrical dual of the complex Klein-Gordon equation

abstract:
  In this paper it is shown that an equivalent to the complex Klein-Gordon
equation can be obtained from the (2+3) dimensional Einstein equations coupled
to a conserved energy momentum tensor. In an explicit toy model we give
matching conditions for what corresponds to the phase, the amplitude, and the
mass of the complex wave function.


title: Rational periodic points for quadratic maps

abstract:
  Let $K$ be a number field. Let $S$ be a finite set of places of $K$
containing all the archimedean ones. Let $R_S$ be the ring of $S$-integers of
$K$. In the present paper we consider endomorphisms of $\pro$ of degree 2,
defined over $K$, with good reduction outside $S$. We prove that there exist
only finitely many such endomorphisms, up to conjugation by ${\rm PGL}_2(R_S)$,
admitting a periodic point in $\po$ of order $>3$. Also, all but finitely many
classes with a periodic point in $\po$ of order 3 are parametrized by an
irreducible curve.


title: Extended silicate dust emission in PG QSOs

abstract:
  This paper addresses the origin of the silicate emission observed in PG QSOs,
based on observations with the Spitzer Space Telescope. Scenarios based on the
unified model suggest that silicate emission in AGN arises mainly from the
illuminated faces of the clouds in the torus at temperatures near sublimation.
However, detections of silicate emission in Type 2 QSOs, and the estimated cool
dust temperatures, argue for a more extended emission region.To investigate
this issue we present the mid-infrared spectra of 23 QSOs. These spectra, and
especially the silicate emission features at ~10 and ~18 mu can be fitted using
dusty narrow line region (NLR) models and a combination of black bodies. The
bolometric luminosities of the QSOs allow us to derive the radial distances and
covering factors for the silicate-emitting dust. The inferred radii are 100-200
times larger than the dust sublimation radius, much larger than the expected
dimensions of the inner torus. Our QSO mid-IR spectra are consistent with the
bulk of the silicate dust emission arising from the dust in the innermost parts
of the NLR.


title: Do superfluid instabilities prevent neutron star precession?

abstract:
  We discuss short wavelength (inertial wave) instabilities present in the
standard two-fluid neutron star model when there is sufficient relative flow
along the superfluid neutron vortex array. We demonstrate that these
instabilities may be triggered in precessing neutron stars, since the angular
velocity vectors of the neutron and proton fluids are misaligned during
precession. The presence of such an instability would render the standard,
solid body rotation, model for free precession inconsistent. Our results
suggest that the standard (Eulerian) slow precession that results for weak drag
between the vortices and the charged fluid (protons and electrons) is not
seriously constrained by the existence of the instability. In contrast, the
fast precession, which results when vortices are strongly coupled to the
charged component, is generally unstable. This implies that fast precession may
not be realised in astrophysical systems


title: Comment on the Neutrino-Mixing Interpretation of the GSI Time Anomaly

abstract:
  It is shown that neutrino mixing cannot explain the GSI time anomaly,
refuting recent claims in this direction. Addendum 1: Remarks on
arXiv:0801.1465. Addendum 2: Quantum effects in GSI nuclear decay.


title: Higgs bosons of a supersymmetric $U(1)'$ model at the ILC

abstract:
  We study the scalar Higgs sector of the next-to-minimal supersymmetric
standard model with an extra U(1), which has two Higgs doublets and a Higgs
singlet, in the light leptophobic $Z'$ scenario where the extra neutral gauge
boson $Z'$ does not couple to charged leptons. In this model, we find that the
sum of the squared coupling coefficients of the three neutral scalar Higgs
bosons to $ZZ$, normalized by the corresponding SM coupling coefficient is
noticeably smaller than unity, due to the effect of the extra U(1), for a
reasonable parameter space of the model, whereas it is unity in the
next-to-minimal supersymmetric standard model. Thus, these two models may be
distinguished if the coupling coefficients of neutral scalar Higgs bosons to
$ZZ$ are measured at the future International Linear Collider by producing them
via the Higgs-strahlung, $ZZ$ fusion, and $WW$ fusion processes.


title: Femtosecond Control of the Magnetization in Ferromagnetic Semiconductors

abstract:
  We develop a theory of collective spin dynamics triggered by ultrafast
optical excitation of ferromagnetic semiconductors. Using the density matrix
equations of motion in the mean field approximation and including magnetic
anisotropy and hole spin dephasing effects, we predict the development of a
light--induced magnetization tilt during ultra--short time intervals comparable
to the pulse duration. This femtosecond dynamics in the coherent temporal
regime is governed by the interband nonlinear optical polarizations and is
followed by a second temporal regime governed by the magnetic anisotropy of the
Fermi sea. We interpret our numerical results by deriving a
Landau--Gilbert--like equation for the collective spin, which demonstrates an
ultrafast correction to the magnetic anisotropy effective field due to second
order coherent nonlinear optical processes. Using the Lindblad semigroup
method, we also derive a contribution to the interband polarization dephasing
determined by the Mn spin and the hole spin dephasing. Our predicted
magnetization tilt and subsequent nonlinear dynamics due to the magnetic
anisotropy can be controlled by varying the optical pulse intensity, duration,
and helicity and can be observed with pump--probe magneto--optical
spectroscopy.


title: Ground State Energy of Current Carriers in Graphene

abstract:
  The ground state energy of current carriers in graphene considered as a
zero-gap semiconductor was calculated in the two-band approximation. The
condition of the electronic (hole) system stability in graphene was obtained.
The possibility of the zero-gap semiconductor-semimetal transition was
discussed.