title:
Relativistic quasiparticle time blocking approximation. Dipole response
  of open-shell nuclei

abstract:
  The self-consistent Relativistic Quasiparticle Random Phase Approximation
(RQRPA) is extended by the quasiparticle-phonon coupling (QPC) model using the
Quasiparticle Time Blocking Approximation (QTBA). The method is formulated in
terms of the Bethe-Salpeter equation (BSE) in the two-quasiparticle space with
an energy-dependent two-quasiparticle residual interaction. This equation is
solved either in the basis of Dirac states forming the self-consistent solution
of the ground state or in the momentum representation. Pairing correlations are
treated within the Bardeen-Cooper-Schrieffer (BCS) model with a
monopole-monopole interaction. The same NL3 set of the coupling constants
generates the Dirac-Hartree-BCS single-quasiparticle spectrum, the static part
of the residual two-quasiparticle interaction and the quasiparticle-phonon
coupling amplitudes. A quantitative description of electric dipole excitations
in the chain of tin isotopes (Z=50) with the mass numbers A = 100, 106, 114,
116, 120, and 130 and in the chain of isotones with (N=50) 88-Sr, 90-Zr, 92-Mo
is performed within this framework.
  The RQRPA extended by the coupling to collective vibrations generates spectra
with a multitude of '2q+phonon' (two quasiparticles plus phonon) states
providing a noticeable fragmentation of the giant dipole resonance as well as
of the soft dipole mode (pygmy resonance) in the nuclei under investigation.
The results obtained for the photo absorption cross sections and for the
integrated contributions of the low-lying strength to the calculated dipole
spectra agree very well with the available experimental data.


title:
Uniform Asymptotics in the Problem of Superfluidity of Classical Liquids
  in Nanotubes

abstract:
  In the preceding papers (see [1, 2]), the superfluidity of the classical
liquid was proved under the assumption that the parameters $N$ and $r$, where
$N$ is the particle number and $r$ it the capillary radius, tend respectively
to infinity and to zero so that $\frac 1N \ll \frac rR$, where $R$ is the
capillary length. In the present paper, this assumption is removed.


title: Multiples of integral points on elliptic curves

abstract:
  If $E$ is a minimal elliptic curve defined over $\ZZ$, we obtain a bound $C$,
depending only on the global Tamagawa number of $E$, such that for any point
$P\in E(\QQ)$, $nP$ is integral for at most one value of $n>C$. As a corollary,
we show that if $E/\QQ$ is a fixed elliptic curve, then for all twists $E'$ of
$E$ of sufficient height, and all torsion-free, rank-one subgroups
$\Gamma\subseteq E'(\QQ)$, $\Gamma$ contains at most 6 integral points.
Explicit computations for congruent number curves are included.


title: Surface-focused Seismic Holography of Sunspots: I. Observations

abstract:
  We present a comprehensive set of observations of the interaction of p-mode
oscillations with sunspots using surface-focused seismic holography. Maps of
travel-time shifts, relative to quiet-Sun travel times, are shown for incoming
and outgoing p modes as well as their mean and difference. We compare results
using phase-speed filters with results obtained with filters that isolate
single p-mode ridges, and further divide the data into multiple temporal
frequency bandpasses. The f mode is removed from the data. The variations of
the resulting travel-time shifts with magnetic-field strength and with the
filter parameters are explored. We find that spatial averages of these shifts
within sunspot umbrae, penumbrae, and surrounding plage often show strong
frequency variations at fixed phase speed. In addition, we find that positive
values of the mean and difference travel-time shifts appear exclusively in
waves observed with phase-speed filters that are dominated by power in the
low-frequency wing of the p1 ridge. We assess the ratio of incoming to outgoing
p-mode power using the ridge filters and compare surface-focused holography
measurements with the results of earlier published p-mode scattering
measurements using Fourier-Hankel decomposition.


title: The Valence Bond Glass phase

abstract:
  We show that a new glassy phase can emerge in presence of strong magnetic
frustration and quantum fluctuations. It is a Valence Bond Glass. We study its
properties solving the Hubbard-Heisenberg model on a Bethe lattice within the
large $N$ limit introduced by Affleck and Marston. We work out the phase
diagram that contains Fermi liquid, dimer and valence bond glass phases. This
new glassy phase has no electronic or spin gap (although a pseudo-gap is
observed), it is characterized by long-range critical valence bond correlations
and is not related to any magnetic ordering. As a consequence it is quite
different from both valence bond crystals and spin glasses.


title: Odd Entries in Pascal's Trinomial Triangle

abstract:
  The nth row of Pascal's trinomial triangle gives coefficients of (1+x+x^2)^n.
Let g(n) denote the number of such coefficients that are odd. We review Moshe's
algorithm for evaluating asymptotics of g(n) -- this involves computing the
Lyapunov exponent for certain 2x2 random matrix products -- and then analyze
further examples with more terms and higher powers of x.


title: Pure Exploration for Multi-Armed Bandit Problems

abstract:
  We consider the framework of stochastic multi-armed bandit problems and study
the possibilities and limitations of forecasters that perform an on-line
exploration of the arms. These forecasters are assessed in terms of their
simple regret, a regret notion that captures the fact that exploration is only
constrained by the number of available rounds (not necessarily known in
advance), in contrast to the case when the cumulative regret is considered and
when exploitation needs to be performed at the same time. We believe that this
performance criterion is suited to situations when the cost of pulling an arm
is expressed in terms of resources rather than rewards. We discuss the links
between the simple and the cumulative regret. One of the main results in the
case of a finite number of arms is a general lower bound on the simple regret
of a forecaster in terms of its cumulative regret: the smaller the latter, the
larger the former. Keeping this result in mind, we then exhibit upper bounds on
the simple regret of some forecasters. The paper ends with a study devoted to
continuous-armed bandit problems; we show that the simple regret can be
minimized with respect to a family of probability distributions if and only if
the cumulative regret can be minimized for it. Based on this equivalence, we
are able to prove that the separable metric spaces are exactly the metric
spaces on which these regrets can be minimized with respect to the family of
all probability distributions with continuous mean-payoff functions.


title: Soft X-ray spectral variability of AM Herculis

abstract:
  Polars (AM Herculis binaries) are a prominent class of bright soft X-ray
sources, many of which were discovered with ROSAT. We present a homogenous
analysis of all the pointed ROSAT PSPC observations of polars subdivided into
two papers that discuss the prototype polar AM Her in detail and summarize the
class properties of all other polars. We derive the high-state soft X-ray flux
and short-term spectral variability of AM Her using a new detector response
matrix and a confirmed flux calibration of the ROSAT PSPC below 0.28 keV. The
best-fit mean single-blackbody temperature and integrated bright-phase energy
flux of AM Her in its April 1991 high state are 27.2 +/- 1.0 eV and (2.6 +/-
0.6) x 10^-9 erg cm^-2s^-1, respectively. The total blackbody flux of a
multi-temperature model that fits both the soft X-ray and the fluctuating
far-ultraviolet components is Fbb = (4.5 +/- 1.5) x 10^-9 erg cm^-2s^-1. The
total accretion luminosity at a distance of 80 pc, Lbb = (2.1 +/- 0.7) x 10^33
erg s-1, implies an accretion rate of Mdot = (2.4 +/- 0.8) x 10^-10 Msun yr^-1
for an 0.78 Msun white dwarf. The soft X-ray flux displays significant
variability on time scales down to 200 ms. Correlated spectral and count-rate
variations are seen in flares on time scales down to 1 s, demonstrating the
heating and cooling associated with individual accretion events. Our spectral
and temporal analysis provides direct evidence for the blobby accretion model
and suggests a connection between the soft X-ray and the fluctuating
far-ultraviolet components.


title:
Measuring the Cosmic Microwave Background Radiation (CMBR) polarization
  with QUIET

abstract:
  A major goal of upcoming experiments measuring the Cosmic Microwave
Background Radiation (CMBR) is to reveal the subtle signature of inflation in
the polarization pattern which requires unprecedented sensitivity and control
of systematics. Since the sensitivity of single receivers has reached
fundamental limits future experiments will take advantage of large receiver
arrays in order to significantly increase the sensitivity. Here we introduce
the Q/U Imaging ExperimenT (QUIET) which will use HEMT-based receivers in chip
packages at 90(40) GHz in the Atacama Desert. Data taking is planned for the
beginning of 2008 with prototype arrays of 91(19) receivers, an expansion to
1000 receivers is foreseen. With the two frequencies and a careful choice of
scan regions there is the promise of effectively dealing with foregrounds and
reaching a sensitivity approaching 10$^{-2}$ for the ratio of the tensor to
scalar perturbations.


title: Soft X-ray in-flight calibration of the ROSAT PSPC

abstract:
  We present an in-flight calibration of the ROSAT PSPC using the incident
spectra of the hot white dwarf HZ43 and the polar AM Her. We derive an absolute
flux calibration of the PSPC using the accurately known soft X-ray spectrum of
HZ43. Corrections to the PSPC response matrix are derived from a comparison of
predicted and observed PSPC spectra of HZ43, supplemented by results for AM
Her. The calibration of the PSPC for photon energies E < 0.28 keV is found to
be accurate to better than 5% refuting earlier reports of a major
miscalibration. Our corrections to the detector response matrices remove
systematic residuals in the pulse height spectra of soft sources.


title: The diffuse X-ray emission from the Galactic center with Simbol-X

abstract:
  Similarly to the larger Galactic ridge, the Galactic center region presents a
hard diffuse emission whose origin has been strongly debated for the past two
decades: does this emission result from the contribution of numerous, yet
unresolved, discrete point sources ? Or does it originate in a truly diffuse,
hot plasma ?
  The Galactic center region (GC) is however different on many respects from
the outer parts of the Galaxy, which makes the diffuse emission issue at the
Galactic center unique. Although recent observations seem to favour a point
sources origin in the far Galactic ridge, the situation is still unclear at the
GC and new observations are required.
  Here we present results on the modeling of the truly diffuse plasma.
Interestingly, such a plasma would strongly affect the dynamics of orbiting
molecular clouds and thus the central engine activity. Discriminating between
the two hypothesis has thus become a crucial issue in the understanding of this
central region that makes the link between the inner small accretion disk and
the large scale Galactic dynamics. We investigate the new inputs we can expect
from Simbol-X on this matter.


title:
Nonhermitian Supersymmetric Partition Functions: the case of one bosonic
  flavor

abstract:
  We discuss the supersymmetric formulation of the nonhermitian $\beta = 2$
random matrix partition function with one bosonic flavor. This partition
function is regularized by adding one conjugate boson and fermion each. A
supersymmetric nonlinear $\sigma$-model for the resulting Goldstone degrees of
freedom is obtained using symmetry arguments only. For a Gaussian probability
distribution the same results are derived using superbosonization and the
complex orthogonal polynomial method. The symmetry arguments apply to any model
with the same symmetries and a mass gap, and demonstrate the universality of
the nonlinear $\sigma$-model.


title: A new code for radiation processes in high energy plasmas

abstract:
  Extreme objects such as X-ray binaries, AGN, or $\gamma$-ray bursters harbor
high energy plasmas whose properties are not well understood yet. Not only are
they responsible of the hard X- and $\gamma$-ray emission we observe but also
they have a strong influence on the main dynamics and energetics of these
objects themselves. Here we present a new kinetic code that solves the
evolution equations for particles and photons around compact objects. It
produces spectra that will be compared with observations from Simbol-X to
constrain the radiation and acceleration processes in these objects.


title: A note on magnetized coronae

abstract:
  X-ray binaries and AGN show observational evidence for magnetized hot
plasmas. Despite years of data, very little is known on these {\it coronae}
especially on the mechanisms responsible for their heating, and most models
simply assume their existence. However, understanding its properties has now
become a key issue of the AGN and microquasars modelling. Here we consider the
effect of a strong vertical magnetic field on the corona AGN and X-ray binaries
and show that its modeling (structure, heating) must be reconsidered. As a
first step, we present one mechanism that could extract energy from the
accretion disks and deposits it in the coronae: the {\it magnetic pumping


title: Spurious Eccentricities of Distorted Binary Components

abstract:
  I discuss the effect of physical distortion on the velocities of close binary
components and how we may use the resulting distortion of velocity curves to
constrain some properties of binary systems, such as inclination and mass
ratio. Precise new velocities for 5 Cet convincingly detect these distortions
with their theoretically predicted phase dependence. We can even use such
distortions of velocity curves to test Lucy's theory of convective gravity
darkening. The observed distortions for TT Hya and 5 Cet require the contact
components of those systems to be gravity darkened, probably somewhat more than
predicted by Lucy's theory but clearly not as much as expected for a radiative
star. These results imply there is no credible evidence for eccentric orbits in
binaries with contact components. I also present some speculative analyses of
the observed properties of a binary encased in a non-rotating common envelope,
if such an object could actually exist, and discuss how the limb darkening of
some recently calculated model atmospheres for giant stars may bias my resuts
for velocity-curve distortions, as well as other results from a wide range of
analyses of binary stars.


title:
Measurement of exclusive D meson decays to eta and eta' final states and
  SU(3) amplitude analysis

abstract:
  Using 281 pb^-1 of data collected with the CLEO-c detector, we present new
measurements of Cabibbo-suppressed decays of D0 and D+ mesons to eta and eta'
final states. We make first observations of D0-->eta'pi0, eta eta, eta eta',
and eta pi+ pi-, and find evidence for D+ --> eta pi+ pi0$, D+ --> eta' pi+ pi0
and D0 --> eta' pi+ pi-. We also report on improved measurements of D0-->eta
pi0, D+ --> eta pi+ and D+ --> etap' pi+. Using the measured two-body
Cabibbo-suppressed decays, we extract amplitudes for specific flavor topologies
and compare them to those from Cabibbo-favored decays.


title:
Model stars for the modelling of galaxies: $\alpha$-enhancement in
  stellar populations models

abstract:
  Stellar population (SP) models are an essential tool to understand the
observations of galaxies and clusters. One of the main ingredients of a SP
model is a library of stellar spectra, and both empirical and theoretical
libraries can been used for this purpose. Here I will start by giving a short
overview of the pros and cons of using theoretical libraries, i.e. model stars,
to produce our galaxy models. Then I will address the question on how
theoretical libraries can be used to model stellar populations, in particular
to explore the effect of $\alpha$-enhancement on spectral observables.


title:
Distributed Joint Source-Channel Coding for arbitrary memoryless
  correlated sources and Source coding for Markov correlated sources using LDPC
  codes

abstract:
  In this paper, we give a distributed joint source channel coding scheme for
arbitrary correlated sources for arbitrary point in the Slepian-Wolf rate
region, and arbitrary link capacities using LDPC codes. We consider the
Slepian-Wolf setting of two sources and one destination, with one of the
sources derived from the other source by some correlation model known at the
decoder. Distributed encoding and separate decoding is used for the two
sources. We also give a distributed source coding scheme when the source
correlation has memory to achieve any point in the Slepian-Wolf rate achievable
region. In this setting, we perform separate encoding but joint decoding.


title: Crab Waist Collision Studies for e+e- Factories

abstract:
  Numerical simulations have shown that the recently proposed "crab waist"
scheme of beam-beam collisions can substantially boost the luminosity of
existing and future electron-positron colliders. In this paper we describe the
crab waist concept and discuss potential advantages that such a scheme can
provide. We also present the results of beam-beam simulations for the two
currently proposed projects based on the crab waist scheme: the DAFNE upgrade
and the Super B-factory project.


title: The complexity of planar graph choosability

abstract:
  A graph $G$ is {\em $k$-choosable} if for every assignment of a set $S(v)$ of
$k$ colors to every vertex $v$ of $G$, there is a proper coloring of $G$ that
assigns to each vertex $v$ a color from $S(v)$. We consider the complexity of
deciding whether a given graph is $k$-choosable for some constant $k$. In
particular, it is shown that deciding whether a given planar graph is
4-choosable is NP-hard, and so is the problem of deciding whether a given
planar triangle-free graph is 3-choosable. We also obtain simple constructions
of a planar graph which is not 4-choosable and a planar triangle-free graph
which is not 3-choosable.


title:
OPE-RchiT matching at order alpha_s: hard gluonic corrections to
  three-point Green functions

abstract:
  In this work we push the matching between the QCD operator product expansion
(OPE) and resonance chiral theory (RchiT) to order alpha_s. To this end we
compute two- and three-point QCD Green functions (GFs) in both theories and
compare the results. GFs which are order parameters of chiral symmetry breaking
make this matching more transparent and thus we concentrate on those. On the
OPE side one needs to calculate the hard-gluon virtual corrections to the quark
condensate, and in particular for three-point GFs this computation was hitherto
missing. We also discuss the need for including the infinite tower of hadronic
states in the hadronic representation of the GF when non-analytic terms such as
logarithms are present in the OPE Wilson coefficients.


title:
Equilibrium and out of equilibrium phase transitions in systems with
  long range interactions and in 2D flows

abstract:
  In self-gravitating stars, two dimensional or geophysical flows and in
plasmas, long range interactions imply a lack of additivity for the energy; as
a consequence, the usual thermodynamic limit is not appropriate. However, by
contrast with many claims, the equilibrium statistical mechanics of such
systems is a well understood subject. In this proceeding, we explain briefly
the classical approach to equilibrium and non equilibrium statistical mechanics
for these systems, starting from first principles. We emphasize recent and new
results, mainly a classification of equilibrium phase transitions, new
unobserved equilibrium phase transition, and out of equilibrium phase
transitions. We briefly discuss what we consider as challenges in this field.


title:
Micro-Macro Modelling of an Array of Spheres Interacting Through
  Lubrication Forces

abstract:
  We consider here a discrete system of spheres interacting through a
lubrication force. This force is dissipative, and singular near contact: it
behaves like the reciprocal of interparticle distance. We propose a macroscopic
constitutive equation which is built as the natural continuous counterpart of
this microscopic lubrication model. This model, which is of the newtonian type,
relies on an elongational viscosity, which is proportional to the reciprocal of
the local fluid fraction. We then establish the convergence in a weak sense of
solutions to the discrete problem towards the solution to the partial
differential equation which we identified as the macroscopic constitutive
equation.


title:
Systematic study of the PDC speckle structure for quantum imaging
  applications

abstract:
  Sub shot noise imaging of weak object by exploiting Parametric Down Converted
light represents a very interesting technological development. A precise
characterization of PDC speckle structure in dependence of pump beam parameters
is a fundamental tool for this application. In this paper we present a first
set of data addressed to this purpose.


title:
Existence of travelling-wave solutions and local well-posedness of the
  Fowler equation

abstract:
  We study the existence of travelling-waves and local well-posedness in a
subspace of $C_b^1(\mathbb{R})$ for a nonlinear evolution equation recently
proposed by Andrew C. Fowler to study the dynamics of dunes.


title:
Minimal positive stencils in meshfree finite difference methods for the
  Poisson equation

abstract:
  Meshfree finite difference methods for the Poisson equation approximate the
Laplace operator on a point cloud. Desirable are positive stencils, i.e. all
neighbor entries are of the same sign. Classical least squares approaches yield
large stencils that are in general not positive. We present an approach that
yields stencils of minimal size, which are positive. We provide conditions on
the point cloud geometry, so that positive stencils always exist. The new
discretization method is compared to least squares approaches in terms of
accuracy and computational performance.


title: Quantum pseudo-randomness from cluster-state quantum computation

abstract:
  We show how to efficiently generate pseudo-random states suitable for quantum
information processing via cluster-state quantum computation. By reformulating
pseudo-random algorithms in the cluster-state picture, we identify a strategy
for optimizing pseudo-random circuits by properly choosing single-qubit
rotations. A Markov chain analysis provides the tool for analyzing convergence
rates to the Haar measure and finding the optimal single-qubit gate
distribution. Our results may be viewed as an alternative construction of
approximate unitary 2-designs.


title: Estimation and Test for Multidimensional Regression Models

abstract:
  This work is concerned with the estimation of multidimensional regression and
the asymptotic behaviour of the test involved in selecting models. The main
problem with such models is that we need to know the covariance matrix of the
noise to get an optimal estimator. We show in this paper that if we choose to
minimise the logarithm of the determinant of the empirical error covariance
matrix, then we get an asymptotically optimal estimator. Moreover, under
suitable assumptions, we show that this cost function leads to a very simple
asymptotic law for testing the number of parameters of an identifiable and
regular regression model. Numerical experiments confirm the theoretical
results.


title:
Constraining the Envelope Structure of L1527 IRS: Infrared Scattered
  Light Modeling

abstract:
  We model Spitzer Space Telescope observations of the Taurus Class 0 protostar
L1527 IRS (IRAS 04368+2557) to provide constraints on its protostellar envelope
structure. The nearly edge-on inclination of L1527 IRS, coupled with the highly
spatially-resolved near to mid-infrared images of this object and the detailed
IRS spectrum, enable us to constrain the outflow cavity geometry quite well,
reducing uncertainties in the other derived parameters. The mid-infrared
scattered light image shows a bright central source within a dark lane; the
aspect ratio of this dark lane is such that it appears highly unlikely to be a
disk shadow. In modeling this dark lane, we conclude that L1527 IRS is probably
not described by a standard TSC envelope with simple bipolar cavities. We find
it necessary to model the dark lane and central source as a modified inner
envelope structure. This structure may be due either to a complex wind-envelope
interaction or induced by the central binary. To fit the overall SED, we
require the central source to have a large near to mid-infrared excess,
suggesting substantial disk accretion. Our model reproduces the overall
morphology and surface brightness distribution of L1527 IRS fairly well, given
the limitations of using axisymmetric models to fit the non-axisymmetric real
object, and the derived envelope infall rates are in reasonable agreement with
some other investigations. IRAC observations of L1527 IRS taken 12 months apart
show variability in total flux and variability in the opposing bipolar
cavities, suggesting asymmetric variations in accretion. We also provide model
images at high resolution for comparison to future observations with current
ground-based instrumentation and future space-based telescopes.


title: Jahn-Teller Distortion in Bimetallic Oxalates

abstract:
  A C$_3$-symmetric crystal-field potential in the Fe(II)Fe(III) bimetallic
oxalates splits the L=2 Fe(II) multiplet into two doublets and a singlet. In
compounds that exhibit magnetic compensation, one of the doublets was predicted
to lie lowest in energy and carry a non-quenched orbital angular momentum $\pm
\ld $, where $\ld $ exceeds a threshold value. In a range of $\ld $, a
Jahn-Teller (JT) distortion increases the energy splitting of the low-lying
doublet and breaks the C$_3$ symmetry of the bimetallic planes around the
ferrimagnetic transition temperature. At low temperatures, the JT distortion
disappears in compounds that display magnetic compensation due to the
competition with the spin-orbit coupling. A comparison with recent measurements
provides strong evidence for this re-entrant, low-temperature JT transition and
a prediction for the normal, high-temperature JT transition. The size of the JT
distortion is estimated using first-principles calculations, which suggest that
the long-range ordering of smaller, non-C$_3$-symmetric organic cations can
eliminate magnetic compensation.


title: Dilepton measurements with CERES

abstract:
  We report on dilepton measurements for central Pb on Au collisions at the top
CERN SPS energy with the upgraded CERES experiment. The dilepton mass spectrum
of 2000 data with improved mass resolution shows an enhancement over the
expectation from hadron decays that is well described by a model including a
strong broadening of the $\rho$ spectral function. The measured excess yield
excludes the dropping mass scenario.
  We also report on the $\phi$ meson measured simultaneously both in the
$K^+K^-$ and in the dilepton decay channel for the first time in high energy
heavy-ion collisions. An excellent agreement is found between the rapidity
densities and the shape of the measured tranverse momentum spectrum. The data
rule out a possible enhancement of the $\phi$ yield in the leptonic over
hadronic channel by a factor larger than 1.6 at 95% CL. CERES results are in
agreement with NA49 results.


title: The Higgs as a Portal to Plasmon-like Unparticle Excitations

abstract:
  A renormalizable coupling between the Higgs and a scalar unparticle operator
O_U of non-integer dimension d_U<2 triggers, after electroweak symmetry
breaking, an infrared divergent vacuum expectation value for O_U. Such IR
divergence should be tamed before any phenomenological implications of the
Higgs-unparticle interplay can be drawn. In this paper we present a novel
mechanism to cure that IR divergence through (scale-invariant) unparticle
self-interactions, which has properties qualitatively different from the
mechanism considered previously. Besides finding a mass gap in the unparticle
continuum we also find an unparticle pole reminiscent of a plasmon resonance.
Such unparticle features could be explored experimentally through their mixing
with the Higgs boson.


title: Gromov-Witten theory of A_n-resolutions

abstract:
  We give a complete solution for the reduced Gromov-Witten theory of resolved
surface singularities of type A_n, for any genus, with arbitrary descendent
insertions. We also present a partial evaluation of the T-equivariant relative
Gromov-Witten theory of the threefold A_n x P^1 which, under a nondegeneracy
hypothesis, yields a complete solution for the theory. The results given here
allow comparison of this theory with the quantum cohomology of the Hilbert
scheme of points on the A_n surfaces. We discuss generalizations to linear
Hodge insertions and to surface resolutions of type D,E. As a corollary, we
present a new derivation of the stationary Gromov-Witten theory of P^1.


title:
Comment on "An Arrow of Time Operator for Standard Quantum Mechanics" -
  a sign of the time!

abstract:
  It is shown that the `arrow of time' operator, M_F, recently suggested by
Strauss et al., in arXiv:0802.2448v1 [quant-ph], is simply related to the sign
of the canonical `time' observable, T (apparently first introduced by Holevo).
In particular, the monotonic decrease of < M_F > corresponds to the fact that <
sgn T > increases monotonically with time. This relationship also provides a
physical interpretation of the property M_F < 1. Some further properties and
possible generalisations are pointed out, including to almost-periodic systems.


title:
Signal duration and the time scale dependence of signal integration in
  biochemical pathways

abstract:
  Signal duration (e.g. the time scales over which an active signaling
intermediate persists) is a key regulator of biological decisions in myriad
contexts such as cell growth, proliferation, and developmental lineage
commitments. Accompanying differences in signal duration are numerous
downstream biological processes that require multiple steps of biochemical
regulation. Here, we present an analysis that investigates how simple
biochemical motifs that involve multiple stages of regulation can be
constructed to differentially process signals that persist at different time
scales. We compute the dynamic gain within these networks and resulting power
spectra to better understand how biochemical networks can integrate signals at
different time scales. We identify topological features of these networks that
allow for different frequency dependent signal processing properties. Our
studies suggest design principles for why signal duration in connection with
multiple steps of downstream regulation is a ubiquitous control motif in
biochemical systems.


title: A Simple Distributed Antenna Processing Scheme for Cooperative Diversity

abstract:
  In this letter the performance of multiple relay channels is analyzed for the
situation in which multiple antennas are deployed only at the relays. The
simple repetition-coded decodeand- forward protocol with two different antenna
processing techniques at the relays is investigated. The antenna combining
techniques are maximum ratio combining (MRC) for reception and transmit
beamforming (TB) for transmission. It is shown that these distributed antenna
combining techniques can exploit the full spatial diversity of the relay
channels regardless of the number of relays and antennas at each relay, and
offer significant power gain over distributed space-time coding techniques.


title: The Opportunistic Transmission of Wireless Worms between Mobile Devices

abstract:
  The ubiquity of portable wireless-enabled computing and communications
devices has stimulated the emergence of malicious codes (wireless worms) that
are capable of spreading between spatially proximal devices. The potential
exists for worms to be opportunistically transmitted between devices as they
move around, so human mobility patterns will have an impact on epidemic spread.
The scenario we address in this paper is proximity attacks from fleetingly
in-contact wireless devices with short-range communication range, such as
Bluetooth-enabled smart phones. An individual-based model of mobile devices is
introduced and the effect of population characteristics and device behaviour on
the outbreak dynamics is investigated. We show through extensive simulations
that in the above scenario the resulting mass-action epidemic models remain
applicable provided the contact rate is derived consistently from the
underlying mobility model. The model gives useful analytical expressions
against which more refined simulations of worm spread can be developed and
tested.


title:
Measurements of a low temperature mechanical dissipation peak in a
  single layer of Ta2O5 doped with TiO2

abstract:
  Thermal noise arising from mechanical dissipation in oxide coatings is a
major limitation to many precision measurement systems, including optical
frequency standards, high resolution optical spectroscopy and interferometric
gravity wave detectors. Presented here are measurements of dissipation as a
function of temperature between 7 K and 290 K in ion-beam sputtered Ta2O5 doped
with TiO2, showing a loss peak at 20 K. Analysis of the peak provides the first
evidence of the source of dissipation in doped Ta2O5 coatings, leading to
possibilities for the reduction of thermal noise effects.


title:
Thin tubes in mathematical physics, global analysis and spectral
  geometry

abstract:
  A thin tube is an $n$-dimensional space which is very thin in $n-1$
directions, compared to the remaining direction, for example the
$\epsilon$-neighborhood of a curve or an embedded graph in $\R^n$ for small
$\epsilon$. The Laplacian on thin tubes and related operators have been studied
in various contexts, with different goals but overlapping techniques. In this
survey we explain some of these contexts, methods and results, hoping to
encourage more interaction between the disciplines mentioned in the title.


title: Power laws in zero-range processes on random networks

abstract:
  We study statistical properties of a zero-range process (ZRP) on random
networks. We derive an analytic expression for the distribution of particles
(also called node occupation distribution) in the steady state of the ZRP in
the ensemble of uncorrelated random graphs. We analyze the dependence of this
distribution on the node-degree distribution. In particular, we show that when
the degree distribution is tuned properly, one can obtain scale-free
fluctuations in the distribution of particles. Such fluctuations lead to a
power law in the distribution of particles, just like in the ZRP with the
hopping rate u(m)=1+b/m on homogeneous graphs.


title: Sous-groupes alg\'ebriques du groupe de Cremona

abstract:
  We give a complete classification of maximal algebraic subgroups of the
Cremona group of the plane and provide algebraic varieties that parametrize the
conjugacy classes.
  -----
  Nous donnons une classification compl\`ete des sous-groupes alg\'ebriques
maximaux du groupe de Cremona du plan et explicitons les vari\'et\'es qui
param\`etrent les classes de conjugaison.


title:
Designer Patterns: Flexible Control of Precipitation through Electric
  Currents

abstract:
  Precipitation patterns generated by A^{+}+B^{-} --> C type reaction-diffusion
processes are studied. It is shown both theoretically and experimentally that
the patterns can be controlled by an appropriately designed, time-dependent
electric current in the system. We describe examples of current dynamics
yielding periodic bands of prescribed wavelength, as well as more complicated
structures. The pattern control is demonstrated experimentally on the
reaction-diffusion-precipitation process 2AgNO_3+K_2Cr_2O_7 -->
Ag_2Cr_2O_7+2KNO_3 taking place in a gel.

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


title: The height of watermelons with wall

abstract:
  We derive asymptotics for the moments as well as the weak limit of the height
distribution of watermelons with p branches with wall. This generalises a
famous result of de Bruijn, Knuth and Rice on the average height of planted
plane trees, and results by Fulmek and Katori et al. on the expected value,
respectively the higher moments, of the height distribution of watermelons with
two branches.
  The asymptotics for the moments depend on the analytic behaviour of certain
multidimensional Dirichlet series. In order to obtain this information we prove
a reciprocity relation satisfied by the derivatives of one of Jacobi's theta
functions, which generalises the well known reciprocity law for Jacobi's theta
functions.

categories: math.CO cond-mat.stat-mech math-ph math.MP math.PR


title:
Classical dimers and dimerized superstructure in orbitally degenerate
  honeycomb antiferromagnet

abstract:
  We discuss the ground state of the spin-orbital model for spin-one ions with
partially filled $t_{2g}$ levels on a honeycomb lattice. We find that the
orbital degrees of freedom induce a spontaneous dimerization of spins and drive
them into nonmagnetic manifold spanned by hard-core dimer (spin-singlet)
coverings of the lattice. The cooperative ``dimer Jahn-Teller'' effect is
introduced through a magnetoelastic coupling and is shown to lift the
orientational degeneracy of dimers leading to a peculiar valence bond crystal
pattern. The present theory provides a theoretical explanation of nonmagnetic
dimerized superstructure experimentally seen in Li$_2$RuO$_3$ compound at low
temperatures.


title:
Proof(s) of the Lamperti representation of Continuous-State Branching
  Processes

abstract:
  This paper uses two new ingredients, namely stochastic differential equations
satisfied by continuous-state branching processes (CSBPs), and a topology under
which the Lamperti transformation is continuous, in order to provide
self-contained proofs of Lamperti's 1967 representation of CSBPs in terms of
spectrally positive L\'evy processes. The first proof is a direct probabilistic
proof, and the second one uses approximations by discrete processes, for which
the Lamperti representation is evident.


title: Exploring the infrared/radio correlation at high redshift

abstract:
  We have analysed the 24um properties of a radio-selected sample in the
Subaru-XMM/Newton Deep Field in order to explore the behaviour of the FIR/radio
relation at high redshifts. Statistically, the correlation is described by q24,
the ratio between the observed flux densities at 24um and 1.4GHz, respectively.
Using 24um data results in considerably more scatter in the correlation than
previous work using data at 60-70um. Nevertheless, we do observe a steady
correlation as a function of redshift, up to z~3.5, suggesting its validity
back to primeval times. We find q24 = 0.30 +/- 0.56 for the observed and q24 =
0.71 +/- 0.47 for the k-corrected radio sample, based on sources with 300uJy <
S(1.4GHz) < 3.2mJy and 24um detections. A suitable k-correction given by a
M82-like mid-IR template suggests no extreme silicate absorption in the bulk of
our radio sample. Using thresholds in q24 to identify radio-excess sources, we
have been able to characterise the transition from radio-loud AGN to
star-forming galaxies and radio-quiet AGN at faint (<1mJy) radio flux
densities. Our results are in broad agreement with previous studies which show
a dominant radio-loud AGN population at >1mJy. The rest-frame U-B colours of
the expected radio-excess population have redder distribution than those that
follow the correlation. This is therefore a promising way to select obscured
Type-2 AGN, with a radio loud nature, missed by deep X-ray observations.
Spectroscopic follow-up of these sources is required to fully test this method.


title: Universality class of fiber bundles with strong heterogeneities

abstract:
  We study the effect of strong heterogeneities on the fracture of disordered
materials using a fiber bundle model. The bundle is composed of two subsets of
fibers, i.e. a fraction 0<\alpha<1 of fibers is unbreakable, while the
remaining 1-\alpha fraction is characterized by a distribution of breaking
thresholds. Assuming global load sharing, we show analytically that there
exists a critical fraction of the components \alpha_c which separates two
qualitatively different regimes of the system: below \alpha_c the burst size
distribution is a power law with the usual exponent \tau=5/2, while above
\alpha_c the exponent switches to a lower value \tau=9/4 and a cutoff function
occurs with a diverging characteristic size. Analyzing the macroscopic response
of the system we demonstrate that the transition is conditioned to disorder
distributions where the constitutive curve has a single maximum and an
inflexion point defining a novel universality class of breakdown phenomena.


title: On Characteristic Polynomials of the Family of Cobweb Posets

abstract:
  This note is a response to one of problems posed by A.K. Kwasniewski in one
of his recent papers. Namely for the sequence of finite cobweb subposets, the
looked for explicit formulas for corresponding sequence of characteristic
polynomials are discovered and delivered here. The recurrence relation defining
arbitrary family of charactristic polynomials of finite cobweb posets is also
derived.


title: Gravitomagnetism in teleparallel gravity

abstract:
  The assumption that matter charges and currents could generate fields, which
are called, by analogy with electromagnetism, gravitoeletric and
gravitomagnetic fields, dates from the origins of General Relativity (GR). On
the other hand, the Teleparallel Equivalent of GR (TEGR), as a gauge theory,
seems to be the ideal scenario to define these fields, based on the gauge field
strength components. The purpose of the present work is to investigate the
nature of the gravitational electric and magnetic fields in the context of the
TEGR, where the tetrad formalism behind it seems to be more appropriated to
deal with phenomena related to observers.
  As our main results, we have obtained, for the first time, the exact
expressions for the gravito-electromagnetic fields for the Schwarzschild
solution that in the linear approximation become the usual expected ones. To
improve our understanding about these fields, we have also studied the geometry
produced by a spherical rotating shell in slow motion and weak field regime.
Again, the expressions obtained are in complete agreement with those of
electromagnetism.


title:
Casimir-Polder force between an atom and a dielectric plate:
  thermodynamics and experiment

abstract:
  The low-temperature behavior of the Casimir-Polder free energy and entropy
for an atom near a dielectric plate are found on the basis of the Lifshitz
theory. The obtained results are shown to be thermodynamically consistent if
the dc conductivity of the plate material is disregarded. With inclusion of dc
conductivity, both the standard Lifshitz theory (for all dielectrics) and its
generalization taking into account screening effects (for a wide range of
dielectrics) violate the Nernst heat theorem. The inclusion of the screening
effects is also shown to be inconsistent with experimental data of Casimir
force measurements. The physical reasons for this inconsistency are elucidated.


title: Repelling Random Walkers in a Diffusion-Coalescence System

abstract:
  We have shown that the steady state probability distribution function of a
diffusion-coalescence system on a one-dimensional lattice of length L with
reflecting boundaries can be written in terms of a superposition of double
shock structures which perform biased random walks on the lattice while
repelling each other. The shocks can enter into the system and leave it from
the boundaries. Depending on the microscopic reaction rates, the system is
known to have two different phases. We have found that the mean distance
between the shock positions is of order L in one phase while it is of order 1
in the other phase.


title: The cobordism class of the moduli space of polygons in $\mathbb{R}^3$

abstract:
  For any vector $r=(r_1,..., r_n)$, let $M_r$ denote the moduli space (under
rigid motions) of polygons in $\mathbb{R}^3$ with $n$-sides whose lengths are
$r_1,...,r_n$. We give an explicit characterization of the oriented
$S^1$-cobordism class of $M_r$ which depends uniquely on the length vector $r$.


title: Authentication over Noisy Channels

abstract:
  In this work, message authentication over noisy channels is studied. The
model developed in this paper is the authentication theory counterpart of
Wyner's wiretap channel model. Two types of opponent attacks, namely
impersonation attacks and substitution attacks, are investigated for both
single message and multiple message authentication scenarios. For each
scenario, information theoretic lower and upper bounds on the opponent's
success probability are derived. Remarkably, in both scenarios, lower and upper
bounds are shown to match, and hence the fundamental limit of message
authentication over noisy channels is fully characterized. The opponent's
success probability is further shown to be smaller than that derived in the
classic authentication model in which the channel is assumed to be noiseless.
These results rely on a proposed novel authentication scheme in which key
information is used to provide simultaneous protection again both types of
attacks.


title:
Inclusive 1-jet Production Cross Section at Small x in QCD: Multiple
  Interactions

abstract:
  We study corrections due to two Pomeron exchanges to the inclusive 1-jet
production cross section in the Regge limit of perturbative QCD for a finite
number of colors. By considering deep inelastic scattering on a weakly bound
two-nucleon system, we carefully follow the logic of the AGK cutting rules and
show, for the single inclusive cross section, that, due to the reggeization of
the gluon, modifications of the AGK cutting rules appear. As our main result,
we investigate and calculate the jet production vertex in the presence of a
two-Pomeron cut correction. Compared to previous studies, we find a novel
structure of the jet vertex which has not been considered before. We discuss a
few implications of this new piece.


title: Optimal Medium Access Protocols for Cognitive Radio Networks

abstract:
  This paper focuses on the design of medium access control protocols for
cognitive radio networks. The scenario in which a single cognitive user wishes
to opportunistically exploit the availability of empty frequency bands within
parts of the radio spectrum having multiple bands is first considered. In this
scenario, the availability probability of each channel is unknown a priori to
the cognitive user. Hence efficient medium access strategies must strike a
balance between exploring (learning) the availability probability of the
channels and exploiting the knowledge of the availability probability
identified thus far. For this scenario, an optimal medium access strategy is
derived and its underlying recursive structure is illustrated via examples. To
avoid the prohibitive computational complexity of this optimal strategy, a low
complexity asymptotically optimal strategy is developed. Next, the
multi-cognitive user scenario is considered and low complexity medium access
protocols, which strike an optimal balance between exploration and exploitation
in such competitive environments, are developed.


title: A general scheme for modeling gamma-ray burst prompt emission

abstract:
  We describe a general method for modeling gamma-ray burst prompt emission. We
find that for the burst to be produced via the synchrotron process unphysical
conditions are required -- the distance of the source from the center of the
explosion ($R_\gamma$) must be larger than $\sim 10^{17}$cm and the source
Lorentz factor $\gta 10^3$; for such a high Lorentz factor the deceleration
radius ($R_d$) is less than $R_\gamma$ even if the number density of particles
in the surrounding medium is as small as $\sim 0.1$ cm$^{-3}$. The result,
$R_\gamma > R_d$, is in contradiction with the early x-ray and optical
afterglow data. The synchrotron-self-Compton (SSC) process fares much better.
There is a large solution space for a typical GRB prompt emission to be
produced via the SSC process. The prompt optical emission accompanying the
burst is found to be very bright ($\lta$ 14 mag; for $z\sim2$) in the SSC
model, which exceeds the observed flux (or upper limit) for most GRBs.
Continuous acceleration of electrons can significantly reduce the optical flux
and bring it down to the observed limits. (Abridged)


title: Measures and their random reals

abstract:
  We study the randomness properties of reals with respect to arbitrary
probability measures on Cantor space. We show that every non-computable real is
non-trivially random with respect to some measure. The probability measures
constructed in the proof may have atoms. If one rules out the existence of
atoms, i.e. considers only continuous measures, it turns out that every
non-hyperarithmetical real is random for a continuous measure. On the other
hand, examples of reals not random for any continuous measure can be found
throughout the hyperarithmetical Turing degrees.


title: Scaling study of dynamical smeared-link clover fermions

abstract:
  We present a framework for phenomenological lattice QCD calculations which
makes use of a tree level Symanzink improved action for gluons and stout-link
Wilson fermions. We give details of our efficient HMC/RHMC algorithm and
present a scaling study of the low-lying N_f=3 baryon spectrum. We find a
scaling region that extends to a~<0.16fm and conclude that our action and
algorithm are suitable for large scale phenomenological investigations of
N_f=2+1 QCD. We expect this conclusion to hold for other comparable actions.


title: Nonsmoothable, locally indicable group actions on the interval

abstract:
  By the Thurston stability theorem, a group of C^1 orientation-preserving
diffeomorphisms of the closed unit interval is locally indicable. We show that
the local order structure of orbits gives a stronger criterion for
nonsmoothability that can be used to produce new examples of locally indicable
groups of homeomorphisms of the interval that are not conjugate to groups of
C^1 diffeomorphisms.


title: The Magnetohydrodynamics of Shock-Cloud Interaction in Three Dimensions

abstract:
  The magnetohydrodynamic evolution of a dense spherical cloud as it interacts
with a strong planar shock is studied, as a model for shock interactions with
density inhomogeneities in the interstellar medium. The cloud is assumed to be
small enough that radiative cooling, thermal conduction, and self-gravity can
be ignored. A variety of initial orientations (including parallel,
perpendicular, and oblique to the incident shock normal) and strengths for the
magnetic field are investigated. During the early stages of the interaction
(less than twice the time taken for the transmitted shock to cross the interior
of the cloud) the structure and dynamics of the shocked cloud is fairly
insensitive to the magnetic field strength and orientation. However, at late
times strong fields substantially alter the dynamics of the cloud, suppressing
fragmentation and mixing by stabilizing the interface at the cloud surface.
Even weak magnetic fields can drastically alter the evolution of the cloud
compared to the hydrodynamic case. Weak fields of different geometries result
in different distributions and amplifications of the magnetic energy density,
which may affect the thermal and non-thermal x-ray emission expected from
shocked clouds associated with, for example, supernovae remnants.


title: Descent Systems for Bruhat Posets

abstract:
  Let $(W,S)$ be a finite Weyl group and let $w\in W$. It is widely appreciated
that the descent set D(w)=\{s\in S | l(ws)<l(w)\} determines a very large and
important chapter in the study of Coxeter groups. In this paper we generalize
some of those results to the situation of the Bruhat poset $W^J$ where
$J\subseteq S$. Our main results here include the identification of a certain
subset $S^J\subseteq W^J$ that convincingly plays the role of $S\subseteq W$,
at least from the point of view of descent sets and related geometry. The point
here is to use this resulting {\em descent system} $(W^J,S^J)$ to explicitly
encode some of the geometry and combinatorics that is intrinsic to the poset
$W^J$. In particular, we arrive at the notion of an {\em augmented poset}, and
we identify the {\em combinatorially smooth} subsets $J\subseteq S$ that have
special geometric significance in terms of a certain corresponding torus
embedding $X(J)$. The theory of $\mathscr{J}$-irreducible monoids provides an
essential tool in arriving at our main results.


title: Variable-range Projection Model for Turbulence-driven Collisions

abstract:
  We discuss the probability distribution of relative speed $\Delta V$ of
inertial particles suspended in a highly turbulent gas when the Stokes numbers,
a dimensionless measure of their inertia, is large. We identify a mechanism
giving rise to the distribution $P(\Delta V) \sim \exp(-C |\Delta V|^{4/3})$
(for some constant $C$). Our conclusions are supported by numerical simulations
and the analytical solution of a model equation of motion. The results
determine the rate of collisions between suspended particles. They are relevant
to the hypothesised mechanism for formation of planets by aggregation of dust
particles in circumstellar nebula.


title: Quantum Anomalous Hall Effect in Hg$_{1-y}$Mn$_{y}$Te Quantum Wells

abstract:
  The quantum Hall effect is usually observed when the two-dimensional electron
gas is subjected to an external magnetic field, so that their quantum states
form Landau levels. In this work we predict that a new phenomenon, the quantum
anomalous Hall effect, can be realized in Hg$_{1-y}$Mn$_{y}$Te quantum wells,
without the external magnetic field and the associated Landau levels. This
effect arises purely from the spin polarization of the $Mn$ atoms, and the
quantized Hall conductance is predicted for a range of quantum well thickness
and the concentration of the $Mn$ atoms. This effect enables dissipationless
charge current in spintronics devices.


title:
Resurrecting the Red from the Dead: Optical Properties of BCGs in X-ray
  Luminous Clusters

abstract:
  We present measurements of surface brightness and colour profiles for the
brightest cluster galaxies (BCGs) in a sample of 48 X-ray luminous galaxy
clusters. These data were obtained as part of the Canadian Cluster Comparison
Project (CCCP). The Kormendy relation of our BCGs is steeper than that of the
local ellipticals, suggesting differences in the assembly history of these
types of systems. We also find that while most BCGs show monotonic colour
gradients consistent with a decrease in metallicity with radius, 25% of the
BCGs show colour profiles that turn bluer towards the centre (blue-cores). We
interpret this bluing trend as evidence for recent star formation. The excess
blue light leads to a typical offset from the red sequence of 0.5 to 1.0 mag in
(g'-r'), thus affecting optical cluster studies that may reject the BCG based
on colour. All of the blue-core BCGs are located within ~10 kpc of the peak in
the cluster X-ray emission. Furthermore, virtually all of the BCGs with recent
star formation are in clusters that lie above the Lx-Tx relation. Based on
photometry alone, these findings suggest that central star formation is a
ubiquitous feature of BCGs in dynamically relaxed cool-core clusters. This
implies that while AGNs and other heating mechanisms are effective at tempering
cooling, they do not full compensate for the energy lost via radiation.


title: Hubble Space Telescope Images of Red Mergers: How Dry are They?

abstract:
  Mergers between red galaxies are observed to be common in the nearby
Universe, and are thought to be the dominant mechanism by which massive
galaxies grow their mass at late times. These ``dry'' mergers can be readily
identified in very deep ground based images, thanks to their extended low
surface brightness tidal features. However, ground-based images lack the
required resolution to determine the morphologies of the merging galaxies, and
to measure the amount of dust and associated gas. We present HST/ACS and WFPC2
observations of a sample of 31 bulge-dominated red-sequence galaxies at z~0.1,
comprised of ongoing mergers, merger remnants, and undisturbed galaxies. Nearly
all galaxies have early-type morphologies and most are well-fit by r^1/4 law
surface brightness profiles. We find that only 10% of the galaxies show
evidence for the presence of dust. The amount of cold gas (or its upper limit)
is calculated from the mean color-excess, assuming a simple relation between
gas mass and dust mass. The gas mass is low for all galaxies, and we find that
Mgas/Mstellar < 3x10^-4. We infer that red mergers in the nearby Universe
mostly involve early-type galaxies containing little cold gas and dust. This
may imply that the progenitors were mostly devoid of gas and/or that feedback
mechanisms are very effective in preventing the gas to cool. The lack of gas in
these objects may also imply a relatively large fraction of binary black holes
in the centers of massive ellipticals.


title:
The Milky Way Rotation Curve and its Vertical Derivatives Inside the
  Solar Circle

abstract:
  We measure the Galactic rotation curve and its first two vertical derivatives
in the first and fourth quadrants of the Milky Way using the 21 cm VGPS and
SGPS. We find tangent velocities of the atomic gas as a function of galactic
longitude and latitude by fitting an analytic line profile to the edges of the
velocity profiles. The shape of the analytic profile depends only on the
tangent velocity and the velocity dispersion of the gas. We use two
complementary methods to analyze the tangent velocities: a global model to fit
typical parameter values and a local fitting routine to examine spatial
variations. We confirm the validity of our fitting routines by testing simple
models. Both the global and local fits are consistent with a vertical falloff
in the rotation curve of -22 +/- 6 km/s/kpc within 100 pc of the Galactic
midplane. The magnitude of the falloff is several times larger than what would
be expected from the change in the potential alone, indicating some other
physical process is important. The falloff we measure is consistent in
magnitude with that measured in the halo gas of other galaxies.


title:
The Fate of the First Galaxies. III. Properties of Primordial Dwarf
  Galaxies and their Impact on the Intergalactic Medium

abstract:
  In two previous papers, we presented simulations of the first galaxies in a
representative volume of the Universe. The simulations are unique because we
model feedback-regulated galaxy formation, using time-dependent,
spatially-inhomogeneous radiative transfer coupled to hydrodynamics. Here, we
study the properties of simulated primordial dwarf galaxies with masses <2x10^8
Msolar and investigate their impact on the intergalactic medium. While many
primordial galaxies are dark, about 100--500 per comoving Mpc^3 are luminous
but relatively faint. They form preferentially in chain structures, and have
low surface brightness stellar spheroids extending to 20% of the virial radius.
Their interstellar medium has mean density n_H~10--100 cm^-3, metallicity Z~
0.01--0.1 Zsolar and can sustain a multi-phase structure. With large scatter,
the mean efficiency of star formation scales with halo mass, <f_*> \propto
M_dm^2, independent of redshift. Because of feedback, halos smaller than a
critical mass, M_crit(z), are devoid of most of their baryons. More
interestingly, we find that dark halos have always a smaller M_crit(z) than
luminous ones. Metal enrichment of the intergalactic medium is inhomogeneous,
with only a 1%--10% volume filling factor of enriched gas with [Z/H]>-3.0 and
10%--50% with [Z/H]>-5.0. At z=10, the fraction of stars with metallicity
Z<10^-3 Zsolar is 10^-6 of the total stellar mass. Although detections of
high-redshift dwarf galaxies with the James Webb Space Telescope will be a
challenge, studies of their fossil records in the local Universe are promising
because of their large spatial density.


title: On IC 10 X-1, the Most Massive Known Stellar-Mass Black Hole

abstract:
  IC 10 X-1 is a variable X-ray source in the Local Group starburst galaxy IC
10 whose optical counterpart is a Wolf-Rayet (WR) star. Prestwich et al. (2007)
recently proposed that it contains the most massive known stellar-mass black
hole (23-34 M_sun), but their conclusion was based on radial velocities derived
from only a few optical spectra, the most important of which was seriously
affected by a CCD defect. Here we present new spectra of the WR star, spanning
one month, obtained with the Keck-I 10 m telescope. The spectra show a periodic
shift in the He II 4686 Ang. emission line as compared with IC 10 nebular lines
such as [O III] 5007 Ang. From this, we calculate a period of 34.93+/-0.04 hr
(consistent with the X-ray period of 34.40+/-0.83 hr reported by Prestwich et
al. 2007) and a radial-velocity semi-amplitude of 370+/-20 km/s. The resulting
mass function is 7.64+/-1.26 M_sun, consistent with that of Prestwich et al.
(2007) (7.8 M_sun). This, combined with the previously estimated (from spectra)
mass of 35 M_sun for the WR star, yields a minimum primary mass of 32.7+/-2.6
M_sun. Even if the WR star has a mass of only 17 M_sun, the minimum primary
mass is 23.1+/-2.1 M_sun. Thus, IC 10 X-1 is indeed a WR/black-hole binary
containing the most massive known stellar-mass black hole.


title:
21cm Absorption by Compact Hydrogen Disks Around Black Holes in
  Radio-Loud Nuclei of Galaxies

abstract:
  The clumpy maser disks observed in some galactic nuclei mark the outskirts of
the accretion disk that fuels the central black hole and provide a potential
site of nuclear star formation. Unfortunately, most of the gas in maser disks
is currently not being probed; large maser gains favor paths that are
characterized by a small velocity gradient and require rare edge-on
orientations of the disk. Here we propose a method for mapping the atomic
hydrogen distribution in nuclear disks through its 21cm absorption against the
radio continuum glow around the central black hole. In NGC 4258, the 21cm
optical depth may approach unity for high angular-resolution (VLBI) imaging of
coherent clumps which are dominated by thermal broadening and have the column
density inferred from X-ray absorption data, ~10^{23}/cm^2. Spreading the 21cm
absorption over the full rotation velocity width of the material in front of
the narrow radio jets gives a mean optical depth of ~0.1. Spectroscopic
searches for the 21cm absorption feature in other galaxies can be used to
identify the large population of inclined gaseous disks which are not masing in
our direction. Follow-up imaging of 21cm silhouettes of accelerating clumps
within these disks can in turn be used to measure cosmological distances.


title:
A spectral Galerkin method for the coupled Orr-Sommerfeld and induction
  equations for free-surface MHD

abstract:
  We develop and test spectral Galerkin schemes to solve the coupled
Orr-Sommerfeld (OS) and induction equations for parallel, incompressible MHD in
free-surface and fixed-boundary geometries. The schemes' discrete bases consist
of Legendre internal shape functions, supplemented with nodal shape functions
for the weak imposition of the stress and insulating boundary conditions. The
orthogonality properties of the basis polynomials solve the matrix-coefficient
growth problem, and eigenvalue-eigenfunction pairs can be computed stably at
spectral orders at least as large as p = 3,000 with p-independent roundoff
error. Accuracy is limited instead by roundoff sensitivity due to non-normality
of the stability operators at large hydrodynamic and/or magnetic Reynolds
numbers (Re, Rm > 4E4). In problems with Hartmann velocity and magnetic-field
profiles we employ suitable Gauss quadrature rules to evaluate the associated
exponentially weighted sesquilinear forms without error. An alternative
approach, which involves approximating the forms by means of
Legendre-Gauss-Lobatto (LGL) quadrature at the 2p - 1 precision level, is found
to yield equal eigenvalues within roundoff error. As a consistency check, we
compare modal growth rates to energy growth rates in nonlinear simulations and
record relative discrepancy smaller than $ 1E-5 $ for the least stable mode in
free-surface flow at Re = 3E4. Moreover, we confirm that the computed normal
modes satisfy an energy conservation law for free-surface MHD with error
smaller than 1E-6. The critical Reynolds number in free-surface MHD is found to
be sensitive to the magnetic Prandtl number Pm, even at the Pm = O(1E-5) regime
of liquid metals.


title: XXZ and Ising Spins on the Triangular Kagome Lattice

abstract:
  The recently fabricated two-dimensional magnetic materials Cu9X2(cpa)6.xH2O
(cpa=2-carboxypentonic acid; X=F,Cl,Br) have copper sites which form a
triangular kagome lattice (TKL), formed by introducing small triangles
(``a-trimers'') inside of each kagome triangle (``b-trimer''). We show that in
the limit where spins residing on b-trimers have Ising character, quantum
fluctuations of XXZ spins residing on the a-trimers can be exactly accounted
for in the absence of applied field. This is accomplished through a mapping to
the kagome Ising model, for which exact analytic solutions exist. We derive the
complete finite temperature phase diagram for this XXZ-Ising model, including
the residual zero temperature entropies of the seven ground state phases.
Whereas the disordered (spin liquid) ground state of the pure Ising TKL model
has macroscopic residual entropy ln72=4.2767... per unit cell, the introduction
of transverse(quantum) couplings between neighboring $a$-spins reduces this
entropy to 2.5258... per unit cell. In the presence of applied magnetic field,
we map the TKL XXZ-Ising model to the kagome Ising model with three-spin
interactions, and derive the ground state phase diagram. A small (or even
infinitesimal) field leads to a new phase that corresponds to a
non-intersecting loop gas on the kagome lattice, with entropy 1.4053... per
unit cell and a mean magnetization for the b-spins of 0.12(1) per site. In
addition, we find that for moderate applied field, there is a critical spin
liquid phase which maps to close-packed dimers on the honeycomb lattice, which
survives even when the a-spins are in the Heisenberg limit.


title: Evolution of the galaxy merger rate in model universes

abstract:
  We investigate the evolution of the galaxy merger rate predicted by two
semi-analytical galaxy formation models implemented on the Millennium
Simulation of dark matter structure growth. The fraction of merging galaxy
pairs at each time-step of the simulation is derived from the galaxy catalogues
obtained by the models and the results are compared with various observational
estimates of merger fractions taken from the literature. We find a good match
between the pair fractions derived from the simulation and the observed
counting of galaxy pairs obtained by different sources in the redshift range 0
< z < 1.2. The predicted evolution of the number of galaxy mergers per Gyr
grows with redshift as an exponential rate proportional to (1+z)^m, with m
ranging from 0.6 to 0.8 for 0 < z < 2, depending on the luminosity and mass
ratios of the merging galaxies. Our results are in agreement with recent
observational results that argue for a flat evolution in the fraction of galaxy
mergers since z ~ 1.2. The weak evolution predicted for the galaxy merger rate
in an hierarchical model universe shows that the mass assembly evolution of
galaxies through mergers does not follow the rapid evolution of the halo merger
rate obtained in previous studies.


title:
Asymptotic formula for the moments of Minkowski question mark function
  in the interval [0,1]

abstract:
  In this paper we prove the asymptotic formula for the moments of Minkowski
question mark function, which describes the distribution of rationals in the
Farey tree. The main idea is to demonstrate that certain a variation of a
Laplace method is applicable in this problem, hence the task reduces to a
number of technical calculations.


title:
MOST Spacebased Photometry of the Transiting Exoplanet System HD 189733:
  Precise Timing Measurements for Transits Across an Active Star

abstract:
  We have measured transit times for HD 189733b passing in front of its bright
(V = 7.67) chromospherically active and spotted parent star. Nearly continuous
broadband optical photometry of this system was obtained with the MOST
(Microvariability & Oscillations of STars) space telescope during 21 days in
August 2006, monitoring 10 consecutive transits. We have used these data to
search for deviations from a constant orbital period which can indicate the
presence of additional planets in the system that are as yet undetected by
Doppler searches. There are no transit timing variations above the level of
${\pm}45$ s, ruling out super-Earths (of masses $1 - 4 M_{\earth}$) in the 1:2
and 2:3 inner resonances and planets of 20 $M_{\earth}$ in the 2:1 outer
resonance of the known planet. We also discuss complications in measuring
transit times for a planet that transits an active star with large star spots,
and how the transits can help constrain and test spot models. This has
implications for the large number of such systems expected to be discovered by
the CoRoT and Kepler missions.


title:
On strongly controllable group codes and mixing group shifts: solvable
  groups, translation nets, and algorithms

abstract:
  The branch group of a strongly controllable group code is a shift group. We
show that a shift group can be characterized in a very simple way. In addition
it is shown that if a strongly controllable group code is labeled with Latin
squares, a strongly controllable Latin group code, then the shift group is
solvable. Moreover the mathematical structure of a Latin square (as a
translation net) and the shift group of a strongly controllable Latin group
code are closely related. Thus a strongly controllable Latin group code can be
viewed as a natural extension of a Latin square to a sequence space. Lastly we
construct shift groups. We show that it is sufficient to construct a simpler
group, the state group of a shift group. We give an algorithm to find the state
group, and from this it is easy to construct a stronlgy controllable Latin
group code.


title: Scaling theory of DNA confined in nanochannels and nanoslits

abstract:
  A scaling analysis is presented of the statistics of long DNA confined in
nanochannels and nanoslits. It is argued that there are several regimes in
between the de Gennes and Odijk limits introduced long ago. The DNA chain folds
back on itself giving rise to a global persistence length which may be very
large owing to entropic deflection. Moreover, there is an orientational
excluded-volume effect between the DNA segments imposed solely by the
nanoconfinement. These two effects cause the chain statistics to be intricate
leading to nontrivial power laws for the chain extension in the intermediate
regimes. It is stressed that DNA confinement within nanochannels differs from
that in nanoslits because the respective orientational excluded-volume effects
are not the same.


title: Quantum key distribution with an unknown and untrusted source

abstract:
  The security of a standard bi-directional "plug & play" quantum key
distribution (QKD) system has been an open question for a long time. This is
mainly because its source is equivalently controlled by an eavesdropper, which
means the source is unknown and untrusted. Qualitative discussion on this
subject has been made previously. In this paper, we present the first
quantitative security analysis on a general class of QKD protocols whose
sources are unknown and untrusted. The securities of standard BB84 protocol,
weak+vacuum decoy state protocol, and one-decoy decoy state protocol, with
unknown and untrusted sources are rigorously proved. We derive rigorous lower
bounds to the secure key generation rates of the above three protocols. Our
numerical simulation results show that QKD with an untrusted source gives a key
generation rate that is close to that with a trusted source.


title: A Review of Spin Determination at the LHC

abstract:
  Spin measurements are crucial in distinguishing major scenarios of TeV scale
new physics once it is discovered at the LHC. We give a brief survey of methods
of measuring the spin of new physics particles at the LHC. We focus on the case
in which a long lived massive neutral particle is produced at the end of every
cascade decay and escape detection. This is the case for R-parity preserving
supersymmetry, Little Higgs models with T-parity, extra-dimensional models with
KK-parity, and a large class of similar models and scenarios. After briefly
commenting on measuring spin by combining mass and rate information, we
concentrate on direct measurement by observing angular correlations among decay
products of the new physics particles. We survey a wide range of possible
channels, discuss the construction of possible correlation variables, and
outline experimental challenges. We also briefly survey the Monte-Carlo tools
which are useful in studying such correlations.


title: Summary of the workshop DUBNA-SPIN 07

abstract:
  During the five days of this workshop we had forty five hours of lectures, so
a tremendous amount of new information was delivered. I will be able only to
highlight some aspects of the numerous interesting topics, which were
discussed, leaving out many of them.


title: Zitterbewegung in Quantum Mechanics -- a research program

abstract:
  Spacetime Algebra (STA) provides unified, matrix-free spinor methods for
rotational dynamics in classical theory as well as quantum mechanics. That
makes it an ideal tool for studying particle models of zitterbewegung and using
them to study zitterbewegung in the Dirac theory. This paper develops a
self-contained dynamical model of the electron as a lightlike particle with
helical zitterbewegung and electromagnetic interactions. It attributes to the
electron an electric dipole moment oscillating with ultrahigh frequency, and
the possibility of observing this directly as a resonance in electron
channeling is analyzed in detail. A modification of the Dirac equation is
suggested to incorporate the oscillating dipole moment. That enables extension
of the Dirac equation to incorporate electroweak interactions in a new way.


title:
Temperature memory and resistive glassy behaviors of a perovskite
  manganite

abstract:
  This paper reports the observations of long-time relaxation, aging, and
temperature memory behaviors of resistance and magnetization in the
ferromagnetic state of a polycrystalline La0.7Ca0.3Mn0.925Ti0.075O3 compound.
The observed glassy dynamics of the electrical transport appears to be
magnetically originated and has a very close association with the magnetic
glassiness of the sample. Phase separation and strong correlation between
magnetic interactions and electronic conduction play the essential roles in
producing such a resistive glassiness. We explain the observed effects in terms
of a coexistence of two competing thermomagnetic processes, domain growth and
magnetic freezing, and propose that hole-doped perovskite manganites can be
considered as "resistive glasses".


title:
Zeta functions and monodromy for surfaces that are general for a toric
  idealistic cluster

abstract:
  In this article we consider surfaces that are general with respect to a 3-
dimensional toric idealistic cluster. In particular, this means that blowing up
a toric constellation provides an embedded resolution of singularities for
these surfaces. First we give a formula for the topological zeta function
directly in terms of the cluster. Then we study the eigenvalues of monodromy.
In particular, we derive a useful criterion to be an eigenvalue. In a third
part we prove the monodromy and the holomorphy conjecture for these surfaces.


title: Enumerating Palindromes and Primitives in Rank Two Free Groups

abstract:
  Let $F= < a,b>$ be a rank two free group. A word $W(a,b)$ in $F$ is {\sl
primitive} if it, along with another group element, generates the group. It is
a {\sl palindrome} (with respect to $a$ and $b$) if it reads the same forwards
and backwards. It is known that in a rank two free group any primitive element
is conjugate either to a palindrome or to the product of two palindromes, but
known iteration schemes for all primitive words give only a representative for
the conjugacy class. Here we derive a new iteration scheme that gives either
the unique palindrome in the conjugacy class or expresses the word as a unique
product of two unique palindromes. We denote these words by $E_{p/q}$ where
$p/q$ is rational number expressed in lowest terms. We prove that $E_{p/q}$ is
a palindrome if $pq$ is even and the unique product of two unique palindromes
if $pq$ is odd. We prove that the pairs $(E_{p/q},E_{r/s})$ generate the group
when $|ps-rq|=1$. This improves the previously known result that held only for
$pq$ and $rs$ both even. The derivation of the enumeration scheme also gives a
new proof of the known results about primitives.


title:
MOST detects variability on tau Bootis possibly induced by its planetary
  companion

abstract:
  (abridged) There is considerable interest in the possible interaction between
parent stars and giant planetary companions in 51 Peg-type systems. We
demonstrate from MOST satellite photometry and Ca II K line emission that there
has been a persistent, variable region on the surface of tau Boo A which
tracked its giant planetary companion for some 440 planetary revolutions and
lies ~68deg (phi=0.8) in advance of the sub-planetary point. The light curves
are folded on a range of periods centered on the planetary orbital period and
phase dependent variability is quantified by Fourier methods and by the mean
absolute deviation (MAD) of the folded data for both the photometry and the Ca
II K line reversals. The region varies in brightness on the time scale of a
rotation by ~1 mmag. In 2004 it resembled a dark spot of variable depth, while
in 2005 it varied between bright and dark. Over the 123 planetary orbits
spanned by the photometry the variable region detected in 2004 and in 2005 are
synchronised to the planetary orbital period within 0.0015 d. The Ca II K line
in 2001, 2002 and 2003 also shows enhanced K-line variability centered on
phi=0.8, extending coverage to some 440 planetary revolutions. The apparently
constant rotation period of the variable region and its rapid variation make an
explanation in terms of conventional star spots unlikely. The lack of
complementary variability at phi=0.3 and the detection of the variable region
so far in advance of the sub-planetary point excludes tidal excitation, but the
combined photometric and Ca II K line reversal results make a good case for an
active region induced magnetically on the surface of tau Boo A by its planetary
companion.


title: Beale-Kato-Majda type condition for Burgers equation

abstract:
  We consider a multidimensional Burgers equation on the torus $\mathbb{T}^d$
and the whole space $\Rd$. We show that, in case of the torus, there exists a
unique global solution in Lebesgue spaces. For a torus we also provide
estimates on the large time behaviour of solutions. In the case of $\Rd$ we
establish the existence of a unique global solution if a Beale-Kato-Majda type
condition is satisfied. To prove these results we use the probabilistic
arguments which seem to be new.


title: A Hardy field extension of Szemeredi's Theorem

abstract:
  In 1975 Szemer\'edi proved that a set of integers of positive upper density
contains arbitrarily long arithmetic progressions. Bergelson and Leibman showed
in 1996 that the common difference of the arithmetic progression can be a
square, a cube, or more generally of the form $p(n)$ where $p(n)$ is any
integer polynomial with zero constant term. We produce a variety of new results
of this type related to sequences that are not polynomial. We show that the
common difference of the progression in Szemer\'edi's theorem can be of the
form $[n^\delta]$ where $\delta$ is any positive real number and $[x]$ denotes
the integer part of $x$. More generally, the common difference can be of the
form $[a(n)]$ where $a(x)$ is any function that is a member of a Hardy field
and satisfies $a(x)/x^k\to \infty$ and $a(x)/x^{k+1}\to 0$ for some
non-negative integer $k$. The proof combines a new structural result for Hardy
sequences, techniques from ergodic theory, and some recent equidistribution
results of sequences on nilmanifolds.


title: A tunneling picture of dual giant Wilson loop

abstract:
  We further discuss a rotating dual giant Wilson loop (D3-brane) solution
constructed in Lorentzian AdS by Drukker et al. The solution is shown to be
composed of a dual giant Wilson loop and a dual giant graviton by minutely
examining its shape. This observation suggests that the corresponding
gauge-theory operator should be a k-th symmetric Wilson loop with the
insertions of dual giant graviton operators. To support the correspondence, the
classical action of the solution should be computed and compared with the
gauge-theory result. For this purpose we first perform a Wick rotation to the
Lorentzian solution by following the tunneling prescription and obtain
Euclidean solutions corresponding to a circular or a straight-line Wilson loop.
In Euclidean signature boundary terms can be properly considered in the
standard manner and the classical action for the Euclidean solutions can be
evaluated. The result indeed reproduces the expectation value of the k-th
symmetric Wilson loop as well as the power-law behavior of the correlation
function of dual giant graviton operators.


title:
On the approximability of the Maximum Agreement SubTree and Maximum
  Compatible Tree problems

abstract:
  This paper has been withdrawn by the corresponding author because the newest
version is now published in Discrete Applied Mathematics.


title: Quantum cohomology of the Hilbert scheme of points on A_n-resolutions

abstract:
  We determine the two-point invariants of the equivariant quantum cohomology
of the Hilbert scheme of points of surface resolutions associated to type A_n
singularities. The operators encoding these invariants are expressed in terms
of the action of the affine Lie algebra \hat{gl}(n+1) on its basic
representation. Assuming a certain nondegeneracy conjecture, these operators
determine the full structure of the quantum cohomology ring. A relationship is
proven between the quantum cohomology and Gromov-Witten/Donaldson-Thomas
theories of A_n x P^1. We close with a discussion of the monodromy properties
of the associated quantum differential equation and a generalization to
singularities of type D and E.


title: The dissociation of the J/psi by light mesons and chiral symmetry

abstract:
  The implication of chiral symmetry for the pion-induced dissociation of the
J/psi is examined in detail. It is shown how the low-energy dynamics of pions,
constrained by chiral symmetry, affect the dissociation cross-section. The
derived soft-pion theorem is then integrated into a Lagrangian model which
includes also abnormal parity content and chiral-symmetric form factors.
Dissociation by the rho meson is also considered.


title: Donaldson-Thomas theory of A_n x P^1

abstract:
  We study the relative Donaldson-Thomas theory of A_n x P^1, where A_n is the
surface resolution of a type A_n singularity. The action of divisor operators
in the theory is expressed in terms of operators of the affine algebra
\hat{gl}(n+1) on Fock space. Assuming a nondegeneracy conjecture, this gives a
complete solution for the theory. The results complete the comparison of this
theory with the Gromov-Witten theory of A_n x P^1 and the quantum cohomology of
the Hilbert scheme of points on A_n.


title:
The outer scale of turbulence in the magneto-ionized Galactic
  interstellar medium

abstract:
  We analyze Faraday rotation and depolarization of extragalactic radio point
sources in the direction of the inner Galactic plane to determine the outer
scale and amplitude of the rotation measure power spectrum. Structure functions
of rotation measure show lower amplitudes than expected when extrapolating
electron density fluctuations to large scales assuming a Kolmogorov spectral
index. This implies an outer scale of those fluctuations on the order of a
parsec, much smaller than commonly assumed. Analysis of partial depolarization
of point sources independently indicates a small outer scale of a Kolmogorov
power spectrum. In the Galaxy's spiral arms, no rotation measure fluctuations
on scales above a few parsecs are measured. In the interarm regions
fluctuations on larger scales than in spiral arms are present, and show power
law behavior with a shallow spectrum. These results suggest that in the spiral
arms stellar sources such as stellar winds or protostellar outflows dominate
the energy injection for the turbulent energy cascade on parsec scales, while
in the interarm regions supernova and super bubble explosions are the main
sources of energy on scales on the order of 100 parsecs.


title: Uniform (m)-condition and Strong Milnor fibrations

abstract:
  In this paper we study the Milnor fibrations associated to real analytic map
germs $\psi:(\mathbb{R}^{m},0) \to (\mathbb{R}^2,0)$ with isolated critical
point at $0\in \mathbb{R}^{m}$. The main result relates the existence of called
Strong Milnor fibrations with a transversality condition of a convenient family
of analytic varieties with isolated critical points at the origin $0\in
\mathbb{R}^{m}$, obtained by projecting the map germ $\psi$ in the family
$L_{-\theta}$ of all lines through the origin in the plane $\mathbb R^{2}.$


title:
Labelling Algorithms for Paired-domination Problems in Block and
  Interval Graphs

abstract:
  Let $G=(V,E)$ be a graph without isolated vertices. A set $S\subseteq V$ is a
paired-domination set if every vertex in $V-S$ is adjacent to a vertex in $S$
and the subgraph induced by $S$ contains a perfect matching. The
paired-domination problem is to determine the paired-domination number, which
is the minimum cardinality of a paired-dominating set. Motivated by a mistaken
algorithm given by Chen, Kang and Ng [ Paired domination on interval and
circular-arc graphs, Disc. Appl. Math. 155(2007),2077-2086], we present two
linear time algorithms to find a minimum cardinality paired-dominating set in
block and interval graphs. In addition, we prove that paired-domination problem
is {\em NP}-complete for bipartite graphs, chordal graphs, even split graphs.


title: Ellipticity and Ergodicity

abstract:
  Let $S=\{S_t\}_{t\geq0}$ be the submarkovian semigroup on $L_2(\Ri^d)$
generated by a self-adjoint, second-order, divergence-form, elliptic operator
$H$ with Lipschitz continuous coefficients $c_{ij}$. Further let $\Omega$ be an
open subset of $\Ri^d$. Under the assumption that $C_c^\infty(\Ri^d)$ is a core
for $H$ we prove that $S$ leaves $L_2(\Omega)$ invariant if, and only if, it is
invariant under the flows generated by the vector fields
$Y_i=\sum^d_{j=1}c_{ij}\partial_j$.


title:
Intersite 4p-3d hybridization in cobalt oxides: a resonant x-ray
  emission spectroscopy study

abstract:
  We report on strong dipole transitions to 3d orbitals of neighboring Co atoms
in the Co 1s x-ray absorption pre-edge. They are revealed by applying
high-resolution resonant x-ray emission spectroscopy (RXES) to compounds
containing CoO6 clusters. When contrasted to quadrupole local 1s3d excitations,
these non-local 1s3d transitions are identified by their energy dispersion and
angular dependence, their sensitivity to second-shell effects (i.e. the
connection mode of the CoO6 octahedra and the bond lengths), and an upwards
energy shift of 2.5 eV due to the poorer screening of the core hole. The
experiment reveals that the intensity of the non-local transitions gauges the
oxygen-mediated 4p-O-3d intersite hybridization. We propose a revised
interpretation of the pre-edges of transition metal compounds. Detailed
analysis of these new features in the pre-edge offers a unique insight in the
oxygen mediated metal-metal interactions in transition metal-based systems,
which is a crucial aspect in orbital ordering and related electronic and
magnetic properties. In addition, the exceptional resolving power of the
present 1s2p RXES experiment allows us to demonstrate the coherent second-order
nature of the underlying scattering process.


title: Heat Kernel and Essential Spectrum of Infinite Graphs

abstract:
  We study the existence and uniqueness of the heat kernel on infinite, locally
finite, connected graphs. For general graphs, a uniqueness criterion, shown to
be optimal, is given in terms of the maximal valence on spheres about a fixed
vertex. A sufficient condition for non-uniqueness is also presented.
Furthermore, we give a lower bound on the bottom of the spectrum of the
discrete Laplacian and use this bound to give a condition ensuring that the
essential spectrum of the Laplacian is empty.


title:
Equivalence of real Milnor's fibrations for quasi homogeneous
  singularities

abstract:
  We are going to use the Euler's vector fields in order to show that for real
quasi-homogeneous singularities with isolated critical value, the Milnor's
fibration in a "thin" hollowed tube involving the zero level and the fibration
in the complement of "link" in sphere are equivalents, since they exist.
Moreover, in order to do that, we explicitly characterize the critical points
of projection $\frac{f}{\|f\|}:S_{\epsilon}^{m}\setminus K_{\epsilon}\to
S^{1}$, where $K_{\epsilon}$ is the link of singularity.


title:
A Chord Diagrammatic Presentation of the Mapping Class Group of a Once
  Bordered Surface

abstract:
  The Ptolemy groupoid is a combinatorial groupoid generated by elementary
moves on marked trivalent fatgraphs with three types of relations. Through the
fatgraph decomposition of Teichm\"uller space, the Ptolemy groupoid is a
mapping class group equivariant subgroupoid of the fundamental path groupoid of
Teichm\"uller space with a discrete set objects. In particular, it leads to an
infinite, but combinatorially simple, presentation of the mapping class group
of an orientable surface.
  In this note, we give a presentation of a full mapping class group
equivariant subgroupoid of the Ptolemy groupoid of an orientable surface with
one boundary component in terms of marked linear chord diagrams, with chord
slides as generators and five types of relations. We also introduce a dual
version of this presentation which has advantages for certain applications, one
of which is given.


title: A comprehensive study of GRB 070125, a most energetic gamma ray burst

abstract:
  We present a comprehensive multiwavelength analysis of the bright, long
duration gamma-ray burst GRB 070125, comprised of observations in $\gamma$-ray,
X-ray, optical, millimeter and centimeter wavebands. Simultaneous fits to the
optical and X-ray light curves favor a break on day 3.78, which we interpret as
the jet break from a collimated outflow. Independent fits to optical and X-ray
bands give similar results in the optical bands but shift the jet break to
around day 10 in the X-ray light curve. We show that for the physical
parameters derived for GRB 070125, inverse Compton scattering effects are
important throughout the afterglow evolution. While inverse Compton scattering
does not affect radio and optical bands, it may be a promising candidate to
delay the jet break in the X-ray band. Radio light curves show rapid flux
variations, which are interpreted as due to interstellar scintillation, and are
used to derive an upper limit of $2.4 \times 10^{17}$ cm on the radius of the
fireball in the lateral expansion phase of the jet. Radio light curves and
spectra suggest a high synchrotron self absorption frequency indicative of the
afterglow shock wave moving in a dense medium. Our broadband modeling favors a
constant density profile for the circumburst medium over a wind-like profile
($R^{-2}$). However, keeping in mind the uncertainty of the parameters, it is
difficult to unambiguously distinguish between the two density profiles. Our
broadband fits suggest that \event is a burst with high radiative efficiency
($> 60 %$).


title: Limit distributions of two-dimensional quantum walks

abstract:
  One-parameter family of discrete-time quantum-walk models on the square
lattice, which includes the Grover-walk model as a special case, is
analytically studied. Convergence in the long-time limit $t \to \infty$ of all
joint moments of two components of walker's pseudovelocity, $X_t/t$ and
$Y_t/t$, is proved and the probability density of limit distribution is
derived. Dependence of the two-dimensional limit density function on the
parameter of quantum coin and initial four-component qudit of quantum walker is
determined. Symmetry of limit distribution on a plane and localization around
the origin are completely controlled. Comparison with numerical results of
direct computer-simulations is also shown.

categories: quant-ph cond-mat.stat-mech math-ph math.MP


title:
Quantum walks on circles in phase space via superconducting circuit
  quantum electrodynamics

abstract:
  We show how a quantum walk can be implemented for the first time in a quantum
quincunx created via superconducting circuit quantum electrodynamics (QED), and
how interpolation from quantum to random walk is implemented by controllable
decoherence using a two resonator system. Direct control over the coin qubit is
difficult to achieve in either cavity or circuit QED, but we show that a
Hadamard coin flip can be effected via direct driving of the cavity, with the
result that the walker jumps between circles in phase space but still exhibits
quantum walk behavior over 15 steps.


title:
Morita equivalent subalgebras of irrational rotation algebras and real
  quadratic fields

abstract:
  In this paper, we determine the isomorphic classes of Morita equivalent
subalgebras of irrational rotation algebras. It is based on the solution of the
quadratic Diophantine equations. We determine the irrational rotation algebras
that have locally trivial inclusions. We compute the index of the locally
trivial inclusions of irrational rotation algebras.


title:
Floer homotopy theory, realizing chain complexes by module spectra, and
  manifolds with corners

abstract:
  In this paper we describe and continue the study begun by the author, Jones,
and Segal, of the homotopy theory that underlies Floer theory. In that paper
the authors addressed the question of realizing a Floer complex as the celluar
chain complex of a CW -spectrum or pro-spectrum, where the attaching maps are
determined by the compactified moduli spaces of connecting orbits. The basic
obstructions to the existence of this realization are the smoothness of these
moduli spaces, and the existence of compatible collections of framings of their
stable tangent bundles. In this note we describe a generalization of this, to
show that when these moduli spaces are smooth, and are oriented with respect to
a generalized cohomology theory E^*, then a Floer E_* -homology theory can be
defined. In doing this we describe a functorial viewpoint on how chain
complexes can be realized by E -module spectra, generalizing the stable
homotopy realization criteria given earlier by the author, Jones, and Segal.
Since these moduli spaces, if smooth, will be manifolds with corners, we give a
discussion about the appropriate notion of orientations of manifolds with
corners.


title:
Conformal Supersymmetry Breaking and Dynamical Tuning of the
  Cosmological Constant

abstract:
  We propose "conformal supersymmetry breaking" models, which tightly relate
the conformal breaking scale (i.e. R-symmetry breaking scale) and the
supersymmetry breaking scale. The both scales are originated from the constant
term in the superpotential through the common source of the R-symmetry
breaking. We show that dynamical tuning between those mass scales significantly
reduces the degree of fine-tuning necessary for generating the almost vanishing
cosmological constant.


title: Markov Property of Continuous Dislocation Band Propagation

abstract:
  Tensile tests were carried out by deforming polycrystalline samples of
substitutional Al-2.5%Mg alloy at room temperature for a range of strain rates.
The Portevin-Le Chatelier (PLC) effect was observed throughout the strain rate
regime. The deformation bands in this region are found to be of type A in
nature. From the analysis of the experimental stress time series data we could
infer that the dynamics of type A dislocation band propagation is a Markov
process.


title: Covering Directed Graphs by In-trees

abstract:
  Given a directed graph $D=(V,A)$ with a set of $d$ specified vertices
$S=\{s_1,...,s_d\}\subseteq V$ and a function $f\colon S \to \mathbb{Z}_+$
where $\mathbb{Z}_+$ denotes the set of non-negative integers, we consider the
problem which asks whether there exist $\sum_{i=1}^d f(s_i)$ in-trees denoted
by $T_{i,1},T_{i,2},..., T_{i,f(s_i)}$ for every $i=1,...,d$ such that
$T_{i,1},...,T_{i,f(s_i)}$ are rooted at $s_i$, each $T_{i,j}$ spans vertices
from which $s_i$ is reachable and the union of all arc sets of $T_{i,j}$ for
$i=1,...,d$ and $j=1,...,f(s_i)$ covers $A$. In this paper, we prove that such
set of in-trees covering $A$ can be found by using an algorithm for the
weighted matroid intersection problem in time bounded by a polynomial in
$\sum_{i=1}^df(s_i)$ and the size of $D$. Furthermore, for the case where $D$
is acyclic, we present another characterization of the existence of in-trees
covering $A$, and then we prove that in-trees covering $A$ can be computed more
efficiently than the general case by finding maximum matchings in a series of
bipartite graphs.


title:
Separating surface magnetic effects in sunspot seismology: new
  time-distance helioseismic diagnostics

abstract:
  Time-distance helioseismic measurements in surface- and deep-focus geometries
for wave-paths that distinguish surface magnetic contributions from those due
to deeper perturbations beneath a large sunspot are presented and analysed.
Travel times showing an increased wave speed region extending down to about 18
Mm beneath the spot are detected in deep-focus geometry that largely avoids use
of wave field within the spot. Direction (in- or out-going wave) and surface
magnetic field (or focus depth) dependent changes in frequency dependence of
travel times are shown and identified to be signatures of wave absorption and
conversion in near surface layers rather than that of shallowness of sunspot
induced perturbations.