title: Studying the properties of the radio emitter in LS 5039

abstract:
  LS 5039 is an X-ray binary that presents non-thermal radio emission. The
radiation at $\sim 5$ GHz is quite steady and optically thin, consisting on a
dominant core plus an extended jet-like structure. There is a spectral turnover
around 1 GHz, and evidence of variability at timescales of 1 yr at 234 MHz. We
investigate the radio emitter properties using the available broadband radio
data, and assuming two possible scenarios to explain the turnover: free-free
absorption in the stellar wind, or synchrotron self-absorption. We use the
relationships between the turnover frequency, the stellar wind density, the
emitter location, size and magnetic field, and the Lorentz factor of the
emitting electrons, as well as a reasonable assumption on the energy budget, to
infer the properties of the low-frequency radio emitter. Also, we put this
information in context with the broadband radio data. The location and size of
the low-frequency radio emitter can be restricted to $\ga$ few AU from the
primary star, its magnetic field to $\sim 3\times 10^{-3}-1$ G, and the
electron Lorentz factors to $\sim 10-100$. The observed variability of the
extended structures seen with VLBA would point to electron bulk velocities $\ga
3\times 10^8$ cm s$^{-1}$, whereas much less variable radiation at 5 GHz would
indicate velocities for the VLBA core $\la 10^8$ cm s$^{-1}$. The emission at
234 MHz in the high state would mostly come from a region larger than the
dominant broadband radio emitter. We suggest a scenario in which secondary
pairs, created via gamma-ray absorption and moving in the stellar wind, are
behind the steady broadband radio core, whereas the resolved jet-like radio
emission would come from a collimated, faster, outflow.


title: Asymptotic Independence in the Spectrum of the Gaussian Unitary Ensemble

abstract:
  Consider a $n \times n$ matrix from the Gaussian Unitary Ensemble (GUE).
Given a finite collection of bounded disjoint real Borel sets $(\Delta_{i,n},\
1\leq i\leq p)$, properly rescaled, and eventually included in any
neighbourhood of the support of Wigner's semi-circle law, we prove that the
related counting measures $({\mathcal N}_n(\Delta_{i,n}), 1\leq i\leq p)$,
where ${\mathcal N}_n(\Delta)$ represents the number of eigenvalues within
$\Delta$, are asymptotically independent as the size $n$ goes to infinity, $p$
being fixed.
  As a consequence, we prove that the largest and smallest eigenvalues,
properly centered and rescaled, are asymptotically independent; we finally
describe the fluctuations of the condition number of a matrix from the GUE.


title: Self-organized criticality and adaptation in discrete dynamical networks

abstract:
  It has been proposed that adaptation in complex systems is optimized at the
critical boundary between ordered and disordered dynamical regimes. Here, we
review models of evolving dynamical networks that lead to self-organization of
network topology based on a local coupling between a dynamical order parameter
and rewiring of network connectivity, with convergence towards criticality in
the limit of large network size $N$. In particular, two adaptive schemes are
discussed and compared in the context of Boolean Networks and Threshold
Networks: 1) Active nodes loose links, frozen nodes aquire new links, 2) Nodes
with correlated activity connect, de-correlated nodes disconnect. These simple
local adaptive rules lead to co-evolution of network topology and -dynamics.
Adaptive networks are strikingly different from random networks: They evolve
inhomogeneous topologies and broad plateaus of homeostatic regulation,
dynamical activity exhibits $1/f$ noise and attractor periods obey a scale-free
distribution. The proposed co-evolutionary mechanism of topological
self-organization is robust against noise and does not depend on the details of
dynamical transition rules. Using finite-size scaling, it is shown that
networks converge to a self-organized critical state in the thermodynamic
limit. Finally, we discuss open questions and directions for future research,
and outline possible applications of these models to adaptive systems in
diverse areas.


title: Model independent constraints on the cosmological expansion rate

abstract:
  We investigate what current cosmological data tells us about the cosmological
expansion rate in a model independent way. Specifically, we study if the
expansion was decelerating at high redshifts and is accelerating now, without
referring to any model for the energy content of the universe, nor to any
specific theory of gravity. This differs from most studies of the expansion
rate which, e.g., assumes some underlying parameterised model for the dark
energy component of the universe. To accomplish this, we have devised a new
method to probe the expansion rate without relying on such assumptions.
  Using only supernova data, we conclude that there is little doubt that the
universe has been accelerating at late times. However, contrary to some
previous claims, we can not determine if the universe was previously
decelerating. For a variety of methods used for constraining the expansion
history of the universe, acceleration is detected from supernovae alone at >5
sigma, regardless of the curvature of the universe. Specifically, using a
Taylor expansion of the scale factor, acceleration today is detected at >12
sigma. If we also include the ratio of the scale of the baryon acoustic
oscillations as imprinted in the cosmic microwave background and in the large
scale distribution of galaxies, it is evident from the data that the expansion
decelerated at high redshifts, but only with the assumption of a flat or
negatively curved universe.


title: Power Spectrum in Krein Space Quantization

abstract:
  The power spectrum of scalar field and space-time metric perturbations
produced in the process of inflation of universe, have been presented in this
paper by an alternative approach to field quantization namely, Krein space
quantization [1,2]. Auxiliary negative norm states, the modes of which do not
interact with the physical world, have been utilized in this method. Presence
of negative norm states play the role of an automatic renormalization device
for the theory.


title: INTEGRAL and XMM-Newton observations of AX J1845.0-0433

abstract:
  AX J1845.0-0433 is a transient high-mass X-ray binary discovered by ASCA. The
source displays bright and short flares observed recently with INTEGRAL. The
transient behaviour and the bright and short flares are studied in order to
understand the accretion mechanisms and the nature of the source. Public
INTEGRAL data and a pointed XMM-Newton observation are used to study in details
the flaring and quiescent phases.
  AX J1845.0-0433 is a persistent X-ray binary with a O9.5I supergiant
companion emitting at a low 0.2-100 keV luminosity of ~1e35 erg/s with seldom
flares reaching luminosities of 1e36 erg/s. The most-accurate X-ray position is
R.A. (2000) =18h45m01s.4 and Dec. = -04deg33'57''.7 (uncertainty 2'').
Variability factors of 50 are observed on time scale as short as hundreds of
seconds. The broad-band high-energy spectrum is typical of wind-fed accreting
pulsars with an intrinsic absorption of NH=(2.6+/-0.2)e22 cm-2, a hard
continuum of Gamma=(0.7-0.9)+/-0.1 and a high-energy cutoff at Ecut=16+/-3 keV.
An excess at low energies is also observed fitted with a black body with a
temperature of kT=0.18+/-0.05 keV. Optically-thin and highly-ionised iron (Fe
XVIII-XIX) located near the supergiant star is detected during the quiescence
phase. The spectral shape of the X-ray continuum is constant. The flare
characteristics in contrast to the persistent quiescent emission suggest that
clumps of mass M~1e22 g are formed within the stellar wind of the supergiant
companion.


title: Search for light custodians in a clean decay channel at the LHC

abstract:
  Models of warped extra dimensions with custodial symmetry usually predict the
existence of a light Kaluza-Klein fermion arising as a partner of the
right-handed top quark, sometimes called light custodians which we will denote
$\tilde{b}_R$. The production of these particles at the LHC can give rise to
multi-W events which could be observed in same-sign dilepton channels, but its
mass reconstruction is challenging. In this letter we study the possibility of
finding a signal for the pair production of this new particle at the LHC
focusing on a rarer, but cleaner decay mode of a light custodian into a $Z$
boson and a $b$-quark. In this mode it would be possible to reconstruct the
light custodian mass.
  In addition to the dominant standard model QCD production processes, we
include the contribution of a Kaluza-Klein gluon first mode. We find that the
$\tilde{b}_R$ stands out from the background as a peak in the $b Z$ invariant
mass. However, when taking into account only the electronic and muonic decay
modes of the $Z$ boson and $b-$tagging efficiencies, the LHC will have access
only to the very light range of masses, $m_{\tilde{b}} = {\cal O} (500)$ GeV.


title:
A longitudinal component in massive gravitational waves arising from a
  bimetric theory of gravity

abstract:
  After a brief review of the work of de Paula, Miranda and Marinho on massive
gravitational waves arising from a bimetric theory of gravity, in this paper it
is shown that the presence of the mass generates a longi- tudinal component in
a particular polarization of the wave. The effect of this polarization on test
masses is performed using the geodesic deviation. A the end of this paper the
detectability of this particular polarization is also discussed, showing that
its angular dependence could, in princi- ple, discriminate such polarization
with respect the two ones of general relativity, if present or future detectors
will achieve a high sensitivity.


title: Connectivity and Critical Currents in Polycrystalline MgB2

abstract:
  Current transport in polycrystalline magnesium diboride is highly non-uniform
(percolative) due to the presence of secondary phases and also due to the
intrinsic anisotropy of the material. The influence of secondary phases on the
transport properties of MgB2 was investigated. Bulk samples were prepared from
a mixture of MgB2 and MgO powders by the ex-situ technique in order to vary the
MgO content systematically. The samples were characterized by resistive and
magnetization measurements. The reduced MgB2 fraction is modeled by a reduced
effective cross section (connectivity), which was assessed directly by the
experiments. The presence of MgO also increases the percolation threshold,
which reduces the zero resistivity (or irreversibility) field.


title: Modular difference logic is hard

abstract:
  In connection with machine arithmetic, we are interested in systems of
constraints of the form x + k \leq y + k'. Over integers, the satisfiability
problem for such systems is polynomial time. The problem becomes NP complete if
we restrict attention to the residues for a fixed modulus N.


title: Physics of ion beam cancer therapy: a multi-scale approach

abstract:
  We propose a multi-scale approach to understand the physics related to
ion-beam cancer therapy. It allows the calculation of the probability of DNA
damage as a result of irradiation of tissues with energetic ions, up to 430
MeV/u. This approach covers different scales, starting from the large scale,
defined by the ion stopping, followed by a smaller scale, defined by secondary
electrons and radicals, and ending with the shortest scale, defined by
interactions of secondaries with the DNA. We present calculations of the
probabilities of single and double strand breaks of DNA, suggest a way to
further expand such calculations, and also make some estimates for glial cells
exposed to radiation.


title:
Probing the complex environments of GRB host galaxies and intervening
  systems: high resolution spectroscopy of GRB050922C

abstract:
  The aim of this paper is to investigate the environment of gamma ray bursts
(GRBs) and the interstellar matter of their host galaxies. We use to this
purpose high resolution spectroscopic observations of the afterglow of
GRB050922C, obtained with UVES/VLT 3.5 hours after the GRB event. We found
that, as for most high resolution spectra of GRBs, the spectrum of the
afterglow of GRB050922C is complex. At least seven components contribute to the
main absorption system at z=2.1992. The detection of lines of neutral elements
like MgI and the detection of fine-structure levels of the ions FeII, SiII and
CII allows us to separate components in the GRB ISM along the line of sight.
Moreover, in addition to the main system, we have analyzed the five intervening
systems between z = 2.077 and z = 1.5664 identified along the GRB line of
sight. GRB afterglow spectra are very complex, but full of information. This
can be used to disentangle the contribution of the different parts of the GRB
host galaxy and to study their properties. Our metallicity estimates agree with
the scenario of GRBs exploding in low metallicity galaxies


title:
Intriguing magnetism of Fe monolayers on hexagonal transition-metal
  surfaces

abstract:
  Using first-principles calculations, we demonstrate that an Fe monolayer can
assume very different magnetic phases on hexagonal hcp (0001) and fcc (111)
surfaces of 4d- and 5d-transition metals. Due to the substrates' d-band
filling, the nearest-neighbor exchange coupling of Fe changes gradually from
antiferromagnetic (AFM) for Fe films on Tc, Re, Ru and Os to ferromagnetic on
Rh, Ir, Pd, and Pt. In combination with the topological frustration on the
triangular lattice of these surfaces the AFM coupling results in a 120-degree
Neel structure for Fe on Re and Ru and an unexpected double-row-wise AFM
structure on Rh, which is a superposition of a left- and right-rotating
90-degree spin spiral.


title:
A note on compact K\"ahler-Ricci flow with positive bisectional
  curvature

abstract:
  We show that for any solution to the K\"ahler-Ricci flow with positive
bisectional curvature on a compact K\"ahler manifold $M^n$, the bisectional
curvature has a uniform positive lower bound. As a consequence, the solution
converges exponentially fast to an K\"ahler-Einstein metric with positive
bisectional curvature as t tends to the infinity, provided we assume the
Futaki-invariant of $M^n$ is zero. This improves a result of D. Phong, J. Song,
J. Sturm and B. Weinkove in which they assumed the stronger condition that
Mabuchi K-energy is bounded from below.


title: Reaction mechanisms in 24Mg+12C and 32S+24Mg

abstract:
  The occurence of "exotic" shapes in light N=Z alpha-like nuclei is
investigated for 24Mg+12C and 32S+24Mg. Various approaches of superdeformed and
hyperdeformed bands associated with quasimolecular resonant structures with low
spin are presented. For both reactions, exclusive data were collected with the
Binary Reaction Spectrometer in coincidence with EUROBALL IV installed at the
VIVITRON Tandem facility of Strasbourg. Specific structures with large
deformation were selectively populated in binary reactions and their associated
$\gamma$-decays studied. The analysis of the binary and ternary reaction
channels is discussed.


title:
Primordial large-scale electromagnetic fields from
  Gravitoelectromagnetic Inflation

abstract:
  We investigate the origin and evolution of primordial electric and magnetic
fields in the early universe, when the expansion is governed by a cosmological
constant $\Lambda_0$. Using the gravitoelectromagnetic inflationary formalism
with $A_0=0$, we obtain the power of spectrums for large-scale magnetic fields
and the inflaton field fluctuations during inflation. A very important fact is
that our formalism is {\em naturally non-conformally invariant}.


title:
Physical ageing studied by a device allowing for rapid thermal
  equilibration

abstract:
  Ageing of organic glasses to the equilibrium liquid state is studied by
measuring the dielectric loss utilizing a microregulator where temperature is
controlled by means of a Peltier element. Compared to conventional equipment
the new device adds almost two orders of magnitude to the span of observable
ageing times. Data for five organic glass-forming liquids are presented. The
existence of an "inner clock" is confirmed by a model-free test showing that
the ageing of structure is controlled by the same material time that controls
the dielectric properties. At long times relaxation is not stretched, but
simple exponential, and there is no "expansion gap" between the limits of the
relaxation rates following up and down jumps to the same temperature.


title:
Hunting for Magnetars in High Mass X-ray Binaries. The Case of
  SuperGiant Fast X-Ray Transients

abstract:
  In this paper we summarize some aspects of the wind accretion theory in high
mass X-ray binaries hosting a magnetic neutron star and a supergiant companion.
In particular, we concentrate on the different types of interaction between the
inflowing wind matter and the neutron star magnetosphere that are relevant when
accretion of matter onto the neutron star surface is largely inhibited; these
include inhibition by the centrifugal and magnetic barriers. We show that very
large luminosity swings (~10^4 or more on time scales as short as hours) can
result from transitions across different regimes. This scenario is then applied
to the activity displayed by supergiant fast X-ray transients (SFXTs), a new
class of high mass X-ray binaries in our galaxy recently discovered with
INTEGRAL. According to this interpretation we argue that SFXTs which display
very large luminosity swings and host a slowly spinning neutron star are
expected to be characterized by magnetar-like fields. Supergiant fast X-ray
transients might thus provide a unique opportunity to detect and study
accreting magnetars in binary systems.


title:
Momentum dependence of the spin susceptibility in two dimensions:
  nonanalytic corrections in the Cooper channel

abstract:
  We consider the effect of rescattering of pairs of quasiparticles in the
Cooper channel resulting in the strong renormalization of second-order
corrections to the spin susceptibility in a two-dimensional electron system. We
use the Fourier expansion of the scattering potential in the vicinity of the
Fermi surface to find that each harmonic becomes renormalized independently.
Since some of those harmonics are negative, the first derivative of the spin
susceptibility is bound to be negative at small momenta, in contrast to the
lowest order perturbation theory result, which predicts a positive slope. We
present in detail an effective method to calculate diagrammatically corrections
to the spin susceptibility to infinite order.


title: Physics Results from the Argo-YBJ Experiment

abstract:
  The ARGO-YBJ experiment has been in stable data taking since November 2007 at
the YangBaJing Cosmic Ray Laboratory (Tibet, P.R. China, 4300 m a.s.l.). In
this paper we report a few selected results in Gamma-Ray Astronomy (Crab Nebula
and Mrk421 observations, search for high energy tails of GRBs) and Cosmic Ray
Physics (Moon and Sun shadow observations, proton-air cross section and
antiproton/proton preliminary measurements).


title:
The saturation scale and its x-dependence from Lambda polarization
  studies

abstract:
  The transverse polarization of forward Lambda hyperons produced in
high-energy p-A collisions is expected to display an extremum at a transverse
momentum around the saturation scale. This was first observed within the
context of the McLerran-Venugopalan model which has an x-independent saturation
scale. The extremum arises due to the k_t-odd nature of the polarization
dependent fragmentation function, which probes approximately the derivative of
the dipole scattering amplitude. The amplitude changes most strongly around the
saturation scale, resulting in a peak in the polarization. We find that the
observation also extends to the more realistic case in which the saturation
scale Q_s is x dependent. Since a range of x and therefore Q_s values is probed
at a given transverse momentum and rapidity, this result is a priori not
expected. Moreover, the measurement of Lambda polarization over a range of x_F
values actually provides a direct probe of the x dependence of the saturation
scale. This novel feature is demonstrated for typical LHC kinematics and for
several phenomenological models of the dipole scattering amplitude. We show
that although the measurement will be challenging, it may be feasible at LHC.
The situation at RHIC is not favorable, because the peak will likely be at too
low transverse momentum of the Lambda to be a trustworthy measure of the
saturation scale.


title:
Magnetic exchange interaction between rare-earth and Mn ions in
  multiferroic hexagonal manganites

abstract:
  We report a study of magnetic dynamics in multiferroic hexagonal manganite
HoMnO3 by far-infrared spectroscopy. Low-temperature magnetic excitation
spectrum of HoMnO3 consists of magnetic-dipole transitions of Ho ions within
the crystal-field split J=8 manifold and of the triangular antiferromagnetic
resonance of Mn ions. We determine the effective spin Hamiltonian for the Ho
ion ground state. The magnetic-field splitting of the Mn antiferromagnetic
resonance allows us to measure the magnetic exchange coupling between the
rare-earth and Mn ions.


title: Hard and Soft Spherical-Bound Stack decoder for MIMO systems

abstract:
  Classical ML decoders of MIMO systems like the sphere decoder, the
Schnorr-Euchner algorithm, the Fano and the stack decoders suffer of high
complexity for high number of antennas and large constellation sizes. We
propose in this paper a novel sequential algorithm which combines the stack
algorithm search strategy and the sphere decoder search region. The proposed
decoder that we call the Spherical-Bound-Stack decoder (SB-Stack) can then be
used to resolve lattice and large size constellations decoding with a reduced
complexity compared to the classical ML decoders.
  The SB-Stack decoder will be further extended to support soft-output
detection over linear channels. It will be shown that the soft SB-Stack decoder
outperforms other MIMO soft decoders in term of performance and complexity.


title:
On the opacity change required to compensate for the revised solar
  composition

abstract:
  Recent revisions of the determination of the solar composition have resulted
in solar models in marked disagreement with helioseismic inferences. The effect
of the composition change on the model is largely caused by the change in the
opacity. Thus we wish to determine an intrinsic opacity change that would
compensate for the revision of the composition. By comparing models computed
with the old and revised composition we determine the required opacity change.
Models are computed with the opacity thus modified and used as reference in
helioseismic inversions to determine the difference between the solar and model
sound speed. An opacity increase varying from around 30 per cent near the base
of the convection zone to a few percent in the solar core results in a
sound-speed profile, with the revised composition, which is essentially
indistinguishable from the original solar model. As a function of the logarithm
of temperature this is well represented by a simple cubic fit. The physical
realism of such a change remains debatable, however.


title:
Target mass corrections to matrix elements in nucleon spin structure
  functions

abstract:
  Target mass corrections to the twist-4 terms $\tilde f_2^{p,n,d}$ as well as
to the leading-twist $\tilde a_2$ are discussed.


title:
A stochastic epidemiological model and a deterministic limit for
  BitTorrent-like peer-to-peer file-sharing networks

abstract:
  In this paper, we propose a stochastic model for a file-sharing peer-to-peer
network which resembles the popular BitTorrent system: large files are split
into chunks and a peer can download or swap from another peer only one chunk at
a time. We prove that the fluid limits of a scaled Markov model of this system
are of the coagulation form, special cases of which are well-known
epidemiological (SIR) models. In addition, Lyapunov stability and settling-time
results are explored. We derive conditions under which the BitTorrent
incentives under consideration result in shorter mean file-acquisition times
for peers compared to client-server (single chunk) systems. Finally, a
diffusion approximation is given and some open questions are discussed.


title:
Terahertz wave generation via optical rectification from multiferroic
  BiFeO3

abstract:
  We detected broadband coherent terahertz (THz) emission from multiferroic
BiFeO3 after illuminating a high-quality bulk single ferroelectric domain
crystal with a ~100 fs optical pulse. The dependence of the emitted THz
waveform on the energy and polarization of the optical pulse is consistent with
the optical rectification mechanism of THz emission. The THz emission provides
a sensitive probe of the electric polarization state of BiFeO3, enabling
applications in ferroelectric memories and ferroelectric domain imaging. We
also report room-temperature THz optical constants of BiFeO3.


title:
Non-driven polymer translocation through a nanopore: computational
  evidence that the escape and relaxation processes are coupled

abstract:
  Most of the theoretical models describing the translocation of a polymer
chain through a nanopore use the hypothesis that the polymer is always relaxed
during the complete process. In other words, models generally assume that the
characteristic relaxation time of the chain is small enough compared to the
translocation time that non-equilibrium molecular conformations can be ignored.
In this paper, we use Molecular Dynamics simulations to directly test this
hypothesis by looking at the escape time of unbiased polymer chains starting
with different initial conditions. We find that the translocation process is
not quite in equilibrium for the systems studied, even though the translocation
time tau is about 10 times larger than the relaxation time tau_r. Our most
striking result is the observation that the last half of the chain escapes in
less than ~12% of the total escape time, which implies that there is a large
acceleration of the chain at the end of its escape from the channel.


title:
Baryon Number, Strangeness and Electric Charge Fluctuations in QCD at
  High Temperature

abstract:
  We analyze baryon number, strangeness and electric charge fluctuations as
well as their correlations in QCD at high temperature. We present results
obtained from lattice calculations performed with an improved staggered fermion
action (p4-action) at two values of the lattice cut-off with almost physical up
and down quark masses and a physical value for the strange quark mass. We
compare these results, with an ideal quark gas at high temperature and a hadron
resonance gas model at low temperature. We find that fluctuations and
correlations are well described by the former already for temperatures about
1.5 times the transition temperature. At low temperature qualitative features
of the lattice results are quite well described by a hadron resonance gas
model. Higher order cumulants, which become increasingly sensitive to the light
pions, however show deviations from a resonance gas in the vicinity of the
transition temperature.


title: Search for the K_S -> e+e- decay with the KLOE detector

abstract:
  We present the result of a direct search for the decay K_S -> e+e-, obtained
with a sample of e+e- -> phi -> K_S K_L events produced at DAFNE, the Frascati
phi-factory, for an integrated luminosity of 1.9 fb^-1. The search has been
performed using a pure K_S beam tagged by the simultaneous detection of a K_L
interaction in the calorimeter. Background rejection has been optimized by
using both kinematic and particle identification cuts. We find BR(K_S -> e+e-)
< 9x10^-9 at 90% CL, which improves by an order of magnitude on the previous
best limit.


title:
A constraint on antigravity of antimatter from precision spectroscopy of
  simple atoms

abstract:
  Consideration of antigravity for antiparticles is an attractive target for
various experimental projects. There are a number of theoretical arguments
against it but it is not quite clear what kind of experimental data and
theoretical suggestions are involved. In this paper we present straightforward
arguments against a possibility of antigravity based on a few simple
theoretical suggestions and some experimental data. The data are: astrophysical
data on rotation of the Solar System in respect to the center of our galaxy and
precision spectroscopy data on hydrogen and positronium. The theoretical
suggestions for the case of absence of the gravitational field are: equality of
electron and positron mass and equality of proton and positron charge. We also
assume that QED is correct at the level of accuracy where it is clearly
confirmed experimentally.


title:
K0 meson physics in the gravitation field: a constraint on the
  equivalence principle

abstract:
  K0-K0bar oscillations are extremely sensitive to the K0 and K0bar energy at
rest. Even assuming m_K0=m_K0bar, the energy is not granted to be the same if
gravitational effects on K0 and K0bar slightly differ. We consider various
gravitation fields present and, in particular, galactic fields, which provide a
negligible acceleration, but relatively large gravitational potential energy. A
constraint from a possible effect of this potential energy on the kaon
oscillations isfound to be
  |(m_g/m_i)_K0-(m_g/m_i)_K0bar| < 8 x 10^-13 atCL=90%.
  The derived constraint is competitive with other tests of universality of the
free fall. Other applications are also discussed.


title:
Gamma ray emission and stochastic particle acceleration in galaxy
  clusters

abstract:
  FERMI (formely GLAST) will shortly provide crucial information on
relativistic particles in galaxy clusters. We discuss non-thermal emission in
the context of general calculations in which relativistic particles (protons
and secondary electrons due to proton-proton collisions) interact with MHD
turbulence generated in the cluster volume during cluster mergers. Diffuse
cluster-scale radio emission (Radio Halos) and hard X-rays are produced during
massive mergers while gamma ray emission, at some level, is expected to be
common in galaxy clusters.


title:
Massive Black Hole Binary Inspirals: Results from the LISA Parameter
  Estimation Taskforce

abstract:
  The LISA Parameter Estimation (LISAPE) Taskforce was formed in September 2007
to provide the LISA Project with vetted codes, source distribution models, and
results related to parameter estimation. The Taskforce's goal is to be able to
quickly calculate the impact of any mission design changes on LISA's science
capabilities, based on reasonable estimates of the distribution of
astrophysical sources in the universe. This paper describes our Taskforce's
work on massive black-hole binaries (MBHBs). Given present uncertainties in the
formation history of MBHBs, we adopt four different population models, based on
(i) whether the initial black-hole seeds are small or large, and (ii) whether
accretion is efficient or inefficient at spinning up the holes. We compare four
largely independent codes for calculating LISA's parameter-estimation
capabilities. All codes are based on the Fisher-matrix approximation, but in
the past they used somewhat different signal models, source parametrizations
and noise curves. We show that once these differences are removed, the four
codes give results in extremely close agreement with each other. Using a code
that includes both spin precession and higher harmonics in the
gravitational-wave signal, we carry out Monte Carlo simulations and determine
the number of events that can be detected and accurately localized in our four
population models.


title: Heteroclinic Ratchets in a System of Four Coupled Oscillators

abstract:
  We study an unusual but robust phenomenon that appears in an example system
of four coupled phase oscillators. We show that the system can have a robust
attractor that responds to a specific detuning between certain pairs of the
oscillators by a breaking of phase locking for arbitrary positive detunings but
not for negative detunings. As the dynamical mechanism behind this is a
particular type of heteroclinic network, we call this a 'heteroclinic ratchet'
because of its dynamical resemblance to a mechanical ratchet.


title: (n-1)-st Koszul homology and the structure of monomial ideals

abstract:
  Koszul homology of monomial ideals provides a description of the structure of
such ideals, not only from a homological point of view (free resolutions, Betti
numbers, Hilbert series) but also from an algebraic viewpoint. In this paper we
show that, in particular, the homology at degree (n-1), with n the number of
indeterminates of the ring, plays an important role for this algebraic
description in terms of Stanley and irreducible decompositions.


title: Discontinuity growth of interval exchange maps

abstract:
  For an interval exchange map, the number of discontinuities of its iterates
either exhibits linear growth or is bounded. This dichotomy is used to prove
that the group of interval exchanges does not contain distortion elements,
giving examples of groups that do not act faithfully via interval exchanges. As
a further application of this dichotomy, a classification of centralizers in
the group of interval exchanges is given. This classification of centralizers
is used to compute the automorphism group of the interval exchange group.


title:
A Duality Approach to the Genealogies of Discrete Non-Neutral
  Wright-Fisher Models

abstract:
  Discrete ancestral problems arising in population genetics are investigated.
In the neutral case, the duality concept has proved of particular interest in
the understanding of backward in time ancestral process from the forward in
time branching population dynamics. We show that duality formulae still are of
great use when considering discrete non-neutral Wright-Fisher models. This
concerns a large class of non-neutral models with completely monotone (CM) bias
probabilities. We show that most classical bias probabilities used in the
genetics literature fall within this CM class or are amenable to it through
some `reciprocal mechanism' which we define. Next, using elementary algebra on
CM functions, some suggested novel evolutionary mechanisms of potential
interest are introduced and discussed.

categories: math.PR cond-mat.stat-mech math.ST q-bio.PE stat.TH


title: Partition relations for Hurewicz-type selection hypotheses

abstract:
  We give a general method to reduce Hurewicz-type selection hypotheses into
standard ones. The method covers the known results of this kind and gives some
new ones.
  Building on that, we show how to derive Ramsey theoretic characterizations
for these selection hypotheses.


title:
A method for estimating the interactions in dissipative particle
  dynamics from particle trajectories

abstract:
  We introduce a method for determining the functional form of the stochastic
and dissipative interactions in a dissipative particle dynamics (DPD) model
from projected phase space trajectories. The DPD model is viewed as a coarse
graining of a detailed dynamics that displays a clear time scale separation.
Based on the Mori-Zwanzig projection operator method we derive a consistency
equation for the stochastic interaction in DPD. The consistency equation can be
solved by an iterative boot strapping procedure. Combined with standard
techniques for estimating the conservative interaction, our method makes it
possible to reconstruct all the forces in a coarse grained DPD model. We
demonstrate how the method works by recreating the interactions in a DPD model
from its phase space trajectory. Furthermore, we discuss how our method can be
used in realistic systems with finite time scale separation.


title: Exclusive diffraction and Pomeron trajectory in ep collisions

abstract:
  The exclusive diffractive production of vector mesons and real photons in ep
collisions has been studied at HERA in a wide kinematic range. Here we present
the most recent experimental results together with a Regge-type model. We
deduce the Pomeranchuk trajectory (Pomeron) by analyzing the HERA data on
deeply virtual Compton scattering (DVCS), and then discuss its basic
properties, namely its apparent "hardness" and its "non-flat" behavior,
different from the claims of some authors.


title: Parameter counting in models with global symmetries

abstract:
  We present rules for determining the number of physical parameters in models
with exact flavor symmetries. In such models the total number of parameters
(physical and unphysical) needed to described a matrix is less than in a model
without the symmetries. Several toy examples are studied in order to
demonstrate the rules. The use of global symmetries in studying the minimally
supersymmetric standard model (MSSM) is examined.


title: Grain Alignment and CMB Polarization Studies

abstract:
  Polarized microwave emission from dust is an important foreground that may
contaminate polarized CMB studies unless carefully accounted for. Modeling of
polarization from dust requires a quantitative understanding of grain
alignment. I review the current status of grain alignment theory outlining
recent advances in quantitative description of the alignment. In particular, I
show that the grain-alignment theory is a predictive one, and its results
nicely match observations. Those indicate that the most important process of
alignment is related to radiative torques acting on irregular grains. The
recently developed analytical model of radiative torque alignment has proven to
be a very efficient tool for predicting the degree of grain alignment. We
expect the alignment theory to further mature before CMBPol flight, which would
ensure a better accounting for the dust-related polarization. At the same time,
CMBPol should provide the additional testing of grain alignment, clarifying the
reliability of polarimetry for tracing of magnetic field.


title:
Bose condensation of interacting gases in traps with and without optical
  lattice

abstract:
  We discuss effects of particle interaction on Bose condensation in
inhomogeneous traps with and without optical lattice. Interaction pushes normal
particles away from the condensate droplet, which is located in the center of
the trap, towards the periphery of the trap where the trapping potential is
large. In the end, the remaining normal particles are squeezed to a quasi-2D
shell around the condensate droplet thus changing the effective dimensionality
of the system. In the absence of the optical lattice the index in the
temperature dependence of the condensate density at the later stages of the
process is close to 2 with a weak dependence on the number of trapped
particles. In the presence of the lattice inside the trap this index acquires a
strong dependence on the number of particles inside the trap and gradually
falls from a 3D to a 2D value with an increase in the number of particles. This
change in index is explained by the lattice-driven spread of the condensate
droplet and the localization of the narrow band particles by the trap
potential.


title: Covalent Molecular Binding in a Susy Background

abstract:
  The Pauli Exclusion principle plays an essential role in the structure of the
current universe. However, in an exactly supersymmetric (susy) universe, the
degeneracy of bosons and fermions plus the ability of fermions to convert in
pairs to bosons implies that the effects of the Pauli principle would be
largely absent. Such a universe may eventually occur through vacuum decay from
our current positive vacuum energy universe to the zero vacuum energy universe
of exact susy. It has been shown that in such a susy universe ionic molecular
binding does exist but homonuclear diatomic molecules are left unbound. In this
paper we provide a first look at covalent binding in a susy background and
compare the properties of the homonuclear bound states with those of the
corresponding molecules in our universe. We find that covalent binding of
diatomic molecules is very strong in an exact susy universe and the interatomic
distances are in general much smaller than in the broken susy universe.


title:
Monomial ideals, almost complete intersections and the Weak Lefschetz
  Property

abstract:
  Many algebras are expected to have the Weak Lefschetz property though this is
often very difficult to establish. We illustrate the subtlety of the problem by
studying monomial and some closely related ideals. Our results exemplify the
intriguing dependence of the property on the characteristic of the ground
field, and on arithmetic properties of the exponent vectors of the monomials.


title: Polarized Tops from Stop Decays at the LHC

abstract:
  In supersymmetric models, scalar top quarks, or stops, generically have
parity-violating couplings to top quarks. As a result, tops produced in stop
decays should be polarized. In this paper, we will argue that this effect may
be observable at the LHC with realistic integrated luminosities, provided that
one of the stops is copiously produced and can decay to a top and a neutralino.
We define the "effective" stop mixing angle, which determines the degree of top
polarization, and discuss the prospects for a measurement of this angle at the
LHC. If some information about the neutralino mixing matrix is available, this
measurement can be used to constrain the mixing angle in the stop sector, one
of the most important ingredients in assessing the naturalness of electroweak
symmetry breaking in the MSSM.


title:
Luminous Red Galaxy Halo Density Field Reconstruction and Application to
  Large Scale Structure Measurements

abstract:
  The complex relationship between the galaxy density field and the underlying
matter field limits our ability to extract cosmological constraints from galaxy
redshift surveys. Our approach is to use halos rather than galaxies to trace
the underlying mass distribution. We identify Fingers-of-God (FOGs) and replace
multiple galaxies in each FOG with a single halo object. This removes the
nonlinear contributions of satellite galaxies, the one-halo term. We test our
method on a large set of high-fidelity mock SDSS Luminous Red Galaxy (LRG)
catalogs. We find that the aggressive FOG compression algorithm adopted in the
LRG P(k) analysis of Tegmark et al. (2006) leads to a ~10% correction to the
underlying matter power spectrum at k = 0.1 h/Mpc and ~40% correction at k=0.2
h/Mpc, thereby compromising the cosmological constraints. In contrast, the
power spectrum of our reconstructed halo density field deviates from the
underlying matter power spectrum by less than 1% for k less than 0.1 h/Mpc and
less than 4% for k less than 0.2 h/Mpc. The reconstructed halo density field
also removes the bias in the measurement of the redshift space distortion
parameter beta induced by the FOG smearing of the linear redshift space
distortions.


title:
Characterizing compact Clifford semigroups that embed into convolution
  and functor-semigroups

abstract:
  We study algebraic and topological properties of the convolution semigroups
of probability measures on a topological groups and show that a compact
Clifford topological semigroup $S$ embeds into the convolution semigroup $P(G)$
over some topological group $G$ if and only if $S$ embeds into the semigroup
$\exp(G)$ of compact subsets of $G$ if and only if $S$ is an inverse semigroup
and has zero-dimensional maximal semilattice. We also show that such a Clifford
semigroup $S$ embeds into the functor-semigroup $F(G)$ over a suitable compact
topological group $G$ for each weakly normal monadic functor $F$ in the
category of compacta such that $F(G)$ contains a $G$-invariant element (which
is an analogue of the Haar measure on $G$).


title: Parts and Wholes. An Inquiry into Quantum and Classical Correlations

abstract:
  ** The primary topic of this dissertation is the study of the relationships
between parts and wholes as described by particular physical theories, namely
generalized probability theories in a quasi-classical physics framework and
non-relativistic quantum theory.
  ** A large part of this dissertation is devoted to understanding different
aspects of four different kinds of correlations: local, partially-local,
no-signaling and quantum mechanical correlations. Novel characteristics of
these correlations have been used to study how they are related and how they
can be discerned via Bell-type inequalities that give non-trivial bounds on the
strength of the correlations.
  ** The study of quantum correlations has also prompted us to study a) the
multi-partite qubit state space with respect to its entanglement and
separability characteristics, and b) the differing strength of the correlations
in separable and entangled qubit states. Results include a novel classification
of multipartite (partial) separability and entanglement, strong constraints on
the monogamy of entanglement and of non-local correlations, and many new
entanglement detection criteria that are directly experimentally accessible.
  ** Because of the generality of the investigation these results also have
strong foundational as well as philosophical repercussions for the different
sorts of physical theories as a whole; notably for the viability of hidden
variable theories for quantum mechanics, for the possibility of doing
experimental metaphysics, for the question of holism in physical theories, and
for the classical vs. quantum dichotomy.


title:
Resolution-dependent mechanisms for bimodal switching-time distributions
  in simulated Fe nanopillars

abstract:
  We study the magnetization-switching statistics following reversal of the
applied field for three separate computational models representing the same
physical system, an iron nanopillar. The primary difference between the models
is the resolution of the computational lattice and, consequently, the intrinsic
parameters that must be rescaled to retain similarity to the physical system.
Considering the first-passage time to zero for the magnetization component in
the longitudinal (easy-axis) direction, we look for applied fields that result
in bimodal distributions of this time for each system and compare the results
to the experimental system. We observe that the relevant fluctuations leading
to bimodal distributions are different for each lattice resolution and result
in magnetization-switching behavior that is unique to each computational model.
Correct model resolution is thus essential for obtaining reliable numerical
results for the system dynamics.


title: TeV Scale Singlet Dark Matter

abstract:
  It is well known that stable weak scale particles are viable dark matter
candidates since the annihilation cross section is naturally about the right
magnitude to leave the correct thermal residual abundance. Many dark matter
searches have focused on relatively light dark matter consistent with weak
couplings to the Standard Model. However, in a strongly coupled theory, or even
if the coupling is just a few times bigger than the Standard Model couplings,
dark matter can have TeV-scale mass with the correct thermal relic abundance.
Here we consider neutral TeV-mass scalar dark matter, its necessary
interactions, and potential signals. We consider signals both with and without
higher-dimension operators generated by strong coupling at the TeV scale, as
might happen for example in an RS scenario. We find some potential for
detection in high energy photons that depends on the dark matter distribution.
Detection in positrons at lower energies, such as those PAMELA probes, would be
difficult though a higher energy positron signal could in principle be
detectable over background. However, a light dark matter particle with
higher-dimensional interactions consistent with a TeV cutoff can in principle
match PAMELA data.


title: Secluded U(1) below the weak scale

abstract:
  A secluded U(1) sector with weak admixture to photons, O(10^{-2}-10^{-3}),
and the scale of the breaking below 1 GeV represents a natural yet poorly
constrained extension of the Standard Model. We analyze g-2 of muons and
electrons together with other precision QED data, as well as radiative decays
of strange particles to constrain mass--mixing angle (m_V-\kappa) parameter
space. We point out that m_V = 214 MeV and \kappa^2 > 3\times 10^{-5} can be
consistent with the hypothesis of HyperCP collaboration, that seeks to explain
the anomalous energy distribution of muon pairs in the \Sigma^+ \to p
\mu^+\mu^- process by a resonance, without direct contradiction to the existing
data on radiative kaon decays. The same parameters lead to O({\rm few} \times
10^{-9}) upward correction to the anomalous magnetic moment of the muon,
possibly relaxing some tension between experimental value and theoretical
determinations of g-2. The ultra-fine energy resolution scan of e^+e^-\to
\mu^+\mu^- cross section and dedicated analysis of lepton spectra from K^+\to
\pi^+ e^+e^- decays should be able to provide a conclusive test of this
hypothesis and improve the constraints on the model.


title: Spontaneous flexoeffect in nanoferroics

abstract:
  Within the Landau-Ginsburg-Devonshire phenomenological approach we study the
ferroic nanosystems properties changes caused by the flexo-effect
(flexoelectric, flexomagnetic, flexoelastic) existing spontaneously due to the
inhomogeneity of order parameters. Exact solution for the spatially
inhomogeneous mechanical displacement vector allowing for flexo-coupling
contribution was found for nanowires and thin pills. Strong influence of
flexo-effect in nanorods and thin pills leads to the displacements of the atoms
resulting into the unit cell symmetry changes, which lead to the phase
transition temperature shift, as well as the flat geometry in radial direction
transforms into the saucer-like one. The new phenomena can be considered as
true manifestation of the spontaneous flexo-effect existence. It was shown that
flexo-effect leads to (a) the appearance of new linear and nonlinear
contribution and renormalization of coefficients before the order parameter
gradient, (b) essentially influences the transition temperature, piezoelectric
response and the spatial distribution of the order parameter, (c) results in
renormalization of extrapolation length in the boundary conditions.


title:
Kondo "underscreening" cloud: spin-spin correlations around a partially
  screened magnetic impurity

abstract:
  We consider the spatial spin correlations around a partially screened spin-1
magnetic moment in a metal exhibiting the underscreened Kondo effect. We find
that the underscreening of the impurity spin results in spatial spin
correlations that are more pronounced as compared to the fully screened Kondo
effect; their power-law decay is weaker because of characteristic logarithmic
corrections at large distances. The spin correlator also changes sign as a
function of distance to the impurity allowing for ferromagnetic correlations
between conduction electron spin density and the local moment. The numerical
findings are shown to be in agreement with the predictions deriving from an
effective ferromagnetic Kondo Hamiltonian.


title:
A Bohr-Sommerfeld quantization formula for quasinormal frequencies of
  AdS black holes

abstract:
  We derive a quantization formula of Bohr-Sommerfeld type for computing
quasinormal frequencies for scalar perturbations in an AdS black hole in the
limit of large scalar mass or spatial momentum. We then apply the formula to
find poles in retarded Green functions of boundary CFTs on $R^{1,d-1}$ and
$RxS^{d-1}$. We find that when the boundary theory is perturbed by an operator
of dimension $\Delta>> 1$, the relaxation time back to equilibrium is given at
zero momentum by ${1 \over \Delta \pi T} << {1 \over \pi T}$. Turning on a
large spatial momentum can significantly increase it. For a generic scalar
operator in a CFT on $R^{1,d-1}$, there exists a sequence of poles near the
lightcone whose imaginary part scales with momentum as $p^{-{d-2 \over d+2}}$
in the large momentum limit. For a CFT on a sphere $S^{d-1}$ we show that the
theory possesses a large number of long-lived quasiparticles whose imaginary
part is exponentially small in momentum.


title: Topology of positively curved 8-dimensional manifolds with symmetry

abstract:
  In this paper we show that a simply connected 8-dimensional manifold M of
positive sectional curvature and symmetry rank $\geq 2$ resembles a rank one
symmetric space in several ways. For example, the Euler characteristic of M is
equal to the Euler characteristic of S^8, H P^2 or C P^4. And if M is
rationally elliptic then M is rationally isomorphic to a rank one symmetric
space. For torsion-free manifolds we derive a much stronger classification. We
also study the bordism type of 8-dimensional manifolds of positive sectional
curvature and symmetry rank $\geq 2$. As an illustration we apply our results
to various families of 8-manifolds.


title:
The Importance of Radiative Feedback for the Stellar Initial Mass
  Function

abstract:
  We investigate the effect of radiative feedback on the star formation process
using radiation hydrodynamical simulations. We repeat the previous
hydrodynamical star cluster formation simulations of Bate et al., and Bate &
Bonnell, but we use a realistic gas equation of state and radiative transfer in
the flux-limited diffusion approximation rather than the original barotropic
equation of state.
  Whereas star formation in the barotropic simulations continued unabated until
the simulation was stopped, we find that radiative feedback essentially
terminates the production of new objects after roughly one local dynamical
time. Radiative feedback also dramatically decreases the propensity of massive
circumstellar discs to fragment and inhibits fragmentation of other dense gas
(e.g. filaments) close to existing protostellar objects. These two effects
decrease the numbers of protostars formed by a factor of approximately 4.
Whereas the original simulations produced more brown dwarfs than stars, the
radiative feedback results in a ratio of stars to brown dwarfs of approximately
5:1, in much better agreement with observations. Most importantly, we find that
although the characteristic stellar mass in the original calculations scaled
linearly with the initial mean Jeans mass, when radiative feedback is included
the characteristic stellar mass is indistinguishable for the two calculations.
We thus propose that the reason the observed initial mass function appears to
be universal is due to self-regulation of the star formation process by
radiative feedback. We present an analytic argument showing how a
characteristic mass may be derived that is relatively independent of initial
conditions such as the cloud's density. (Abridged)


title:
Tunable magnetic exchange interactions in manganese-doped inverted
  core/shell ZnSe/CdSe nanocrystals

abstract:
  Magnetic doping of semiconductor nanostructures is actively pursued for
applications in magnetic memory and spin-based electronics. Central to these
efforts is a drive to control the interaction strength between carriers
(electrons and holes) and the embedded magnetic atoms. In this respect,
colloidal nanocrystal heterostructures provide great flexibility via
growth-controlled `engineering' of electron and hole wavefunctions within
individual nanocrystals. Here we demonstrate a widely tunable magnetic sp-d
exchange interaction between electron-hole excitations (excitons) and
paramagnetic manganese ions using `inverted' core-shell nanocrystals composed
of Mn-doped ZnSe cores overcoated with undoped shells of narrower-gap CdSe.
Magnetic circular dichroism studies reveal giant Zeeman spin splittings of the
band-edge exciton that, surprisingly, are tunable in both magnitude and sign.
Effective exciton g-factors are controllably tuned from -200 to +30 solely by
increasing the CdSe shell thickness, demonstrating that strong quantum
confinement and wavefunction engineering in heterostructured nanocrystal
materials can be utilized to manipulate carrier-Mn wavefunction overlap and the
sp-d exchange parameters themselves.


title:
Gravitational Wave Recoil Oscillations of Black Holes: Implications for
  Unified Models of Active Galactic Nuclei

abstract:
  We consider the consequences of gravitational wave recoil for unified models
of active galactic nuclei (AGNs). Spatial oscillations of supermassive black
holes (SMBHs) around the cores of galaxies following gravitational wave (GW)
recoil imply that the SMBHs spend a significant fraction of time off-nucleus,
at scales beyond that of the molecular obscuring torus. Assuming reasonable
distributions of recoil velocities, we compute the off-core timescale of
(intrinsically type-2) quasars. We find that roughly one-half of major mergers
result in a SMBH being displaced beyond the torus for a time of 30 Myr or more,
comparable to quasar activity timescales. Since major mergers are most strongly
affected by GW recoil, our results imply a deficiency of type 2 quasars in
comparison to Seyfert 2 galaxies. Other consequences of the recoil oscillations
for the observable properties of AGNs are also discussed.


title: A unifying view of Gamma Ray Burst Afterglows

abstract:
  We selected a sample of 33 Gamma Ray Bursts (GRBs) detected by Swift, with
known redshift and optical extinction at the host frame. For these, we
constructed the de-absorbed and K-corrected X-ray and optical rest frame light
curves. These are modelled as the sum of two components: emission from the
forward shock due to the interaction of a fireball with the circum-burst medium
and an additional component, treated in a completely phenomenological way. The
latter can be identified, among other possibilities, as "late prompt" emission
produced by a long lived central engine with mechanisms similar to those
responsible for the production of the "standard" early prompt radiation. Apart
from flares or re-brightenings, that we do not model, we find a good agreement
with the data, despite of their complexity and diversity. Although based in
part on a phenomenological model with a relatively large number of free
parameters, we believe that our findings are a first step towards the
construction of a more physical scenario. Our approach allows us to interpret
the behaviour of the optical and X-ray afterglows in a coherent way, by a
relatively simple scenario. Within this context it is possible to explain why
sometimes no jet break is observed; why, even if a jet break is observed, it is
often chromatic; why the steepening after the jet break time is often shallower
than predicted. Finally, the decay slope of the late prompt emission after the
shallow phase is found to be remarkably similar to the time profile expected by
the accretion rate of fall-back material (i.e. proportional to t^{-5/3}),
suggesting that this can be the reason why the central engine can be active for
a long time.


title:
An EVLA search for water megamaser emission in the submm galaxy SMM
  J16359+6612 at z=2.5

abstract:
  Using the Expanded Very Large Array, we have conducted a search for 22.2 GHz
H2O megamaser emission in the strongly lensed submm galaxy, SMM J16359+6612 at
z=2.517. This object is lensed into three components, and after a correction
for magnification is applied to its submm-wavelength flux density, it is
typical of the bulk of the high-redshift, submm galaxy population responsible
for the 850 um extragalactic background (S(850um)~1 mJy). We do not detect any
H2O megamaser emission, but the lensing allows us to place an interesting
constraint on the luminosity of any megamasers present, L(H2O) < 5305 solar
luminosities for an assumed linewidth of 80 km/s. Because the far-infrared
luminosity in submm galaxies is mainly powered by star formation, and very
luminous H2O megamasers are more commonly associated with quasar activity, it
could be that blind searches for H2O megamasers will not be an effective means
of determining redshifts for less luminous members of the submm galaxy
population.


title: Constraining Spinning Dust Parameters with the WMAP Five-Year Data

abstract:
  We characterize spinning dust emission in the warm ionized medium by
comparing templates of Galactic dust and Halpha with the 5-year maps from the
Wilkinson Microwave Anisotropy Probe. The Halpha-correlated microwave emission
deviates from the thermal bremsstrahlung (free-free) spectrum expected for
ionized gas, exhibiting an additional broad bump peaked at ~40 GHz which
provides ~20% of the peak intensity. We confirm that the bump is consistent
with a modified Draine & Lazarian (1998) spinning dust model, though the peak
frequency of the emission is somewhat lower than the 50 GHz previously claimed.
This frequency shift results from systematic errors in the large-scale modes of
the 3-year WMAP data which have been corrected in the 5-year data release. We
show that the bump is not the result of errors in the Halpha template by
analyzing regions of high free-free intensity, where the WMAP K-band map may be
used as the free-free template. We rule out a pure free-free spectrum for the
Halpha-correlated emission at high confidence: ~27sigma for the nearly full-sky
fit, even after marginalizing over the CMB cross-correlation bias. We also
extend the previous analysis by searching the parameter space of the Draine &
Lazarian model but letting the amplitude float. The best fit for reasonable
values of the characteristic electric dipole moment and density requires an
amplitude factor of ~0.3. This suggests that small PAHs in the warm ionized
medium are depleted by a factor of ~3.


title: Simulation of large deviation functions using population dynamics

abstract:
  In these notes we present a pedagogical account of the population dynamics
methods recently introduced to simulate large deviation functions of dynamical
observables in and out of equilibrium. After a brief introduction on large
deviation functions and their simulations, we review the method of Giardin\`a
\emph{et al.} for discrete time processes and that of Lecomte \emph{et al.} for
the continuous time counterpart. Last we explain how these methods can be
modified to handle static observables and extract information about
intermediate times.


title: Measuring the Sources of the Intergalactic Ionizing Flux

abstract:
  We use a wide-field (0.9 square degree) X-ray sample with optical and GALEX
ultraviolet observations to measure the contribution of Active Galactic Nuclei
(AGNs) to the ionizing flux as a function of redshift. Our analysis shows that
the AGN contribution to the metagalactic ionizing background peaks around z=2.
The measured values of the ionizing background from the AGNs are lower than
previous estimates and confirm that ionization from AGNs is insufficient to
maintain the observed ionization of the intergalactic medium (IGM) at z>3. We
show that only sources with broad lines in their optical spectra have
detectable ionizing flux and that the ionizing flux seen in an AGN is not
correlated with its X-ray color. We also use the GALEX observations of the
GOODS-N region to place a 2-sigma upper limit of 0.008 on the average
ionization fraction fnu(700 A)/fnu(1500 A) for 626 UV selected galaxies in the
redshift range z=0.9-1.4. We then use this limit to estimate an upper bound to
the galaxy contribution in the redshift range z=0-5. If the z~1.15 ionization
fraction is appropriate for higher redshift galaxies, then contributions from
the galaxy population are also too low to account for the IGM ionization at the
highest redshifts (z>4).


title:
Galaxy evolution by color-log(n) type since redshift unity in the Hubble
  Ultra Deep Field

abstract:
  We explore the use of the color-log(n) plane (where n is the global Sersic
index) as a tool for subdividing the high redshift galaxy population in a
physically-motivated manner. Using a series of volume-limited samples out to
z=1.5 in the Hubble Ultra Deep Field (UDF) we confirm the correlation between
color-log(n) plane position and visual morphology observed locally and in other
high redshift studies in the color and/or structure domain. Via comparison to a
low redshift sample from the Millennium Galaxy Catalogue we quantify evolution
by color-log(n) type, accounting separately for the specific selection and
measurement biases against each. Specifically, we measure decreases in B-band
surface brightness of 1.57 +/- 0.22 mag/sq.arcsec and 1.65 +/- 0.22
mag/sq.arcsec for `blue, diffuse' and `red, compact' galaxies respectively
between redshift unity and the present day.


title:
GRB 080503: Implications of a Naked Short Gamma-Ray Burst Dominated by
  Extended Emission

abstract:
  We report on observations of GRB 080503, a short gamma-ray burst with very
bright extended emission (about 30 times the gamma-ray fluence of the initial
spike) in conjunction with a thorough comparison to other short Swift events.
In spite of the prompt-emission brightness, however, the optical counterpart is
extraordinarily faint, never exceeding 25 mag in deep observations starting at
~1 hr after the BAT trigger. The optical brightness peaks at ~1 day and then
falls sharply in a manner similar to the predictions of Li & Paczynski (1998)
for supernova-like emission following compact-binary mergers. However, a
shallow spectral index and similar evolution in X-rays inferred from Chandra
observations are more consistent with an afterglow interpretation. The extreme
faintness of this probable afterglow relative to the bright gamma-ray emission
argues for a very low-density medium surrounding the burst (a "naked" GRB),
consistent with the lack of a coincident host galaxy down to 28.5 mag in deep
HST imaging. Our observations reinforce the notion that short GRBs generally
occur outside regions of active star formation, but demonstrate that in some
cases the luminosity of the extended prompt emission can greatly exceed that of
the short spike, which may constrain theoretical interpretation of this class
of events. Because most previous BAT short bursts without observed extended
emission are too faint for this signature to have been detectable even if it
were present at typical level, conclusions based solely on the observed
presence or absence of extended emission in the existing Swift sample are
premature. (abridged)


title:
A robust morphological classification of high-redshift galaxies using
  support vector machines on seeing limited images. II. Quantifying
  morphological k-correction in the COSMOS field at 1<z<2: Ks band vs. I band

abstract:
  We quantify the effects of \emph{morphological k-correction} at $1<z<2$ by
comparing morphologies measured in the K and I-bands in the COSMOS area.
Ks-band data have indeed the advantage of probing old stellar populations for
$z<2$, enabling a determination of galaxy morphological types unaffected by
recent star formation. In paper I we presented a new non-parametric method to
quantify morphologies of galaxies on seeing limited images based on support
vector machines. Here we use this method to classify $\sim$$50 000$ $Ks$
selected galaxies in the COSMOS area observed with WIRCam at CFHT. The obtained
classification is used to investigate the redshift distributions and number
counts per morphological type up to $z\sim2$ and to compare to the results
obtained with HST/ACS in the I-band on the same objects from other works. We
associate to every galaxy with $Ks<21.5$ and $z<2$ a probability between 0 and
1 of being late-type or early-type. The classification is found to be reliable
up to $z\sim2$. The mean probability is $p\sim0.8$. It decreases with redshift
and with size, especially for the early-type population but remains above
$p\sim0.7$. The classification is globally in good agreement with the one
obtained using HST/ACS for $z<1$. Above $z\sim1$, the I-band classification
tends to find less early-type galaxies than the Ks-band one by a factor
$\sim$1.5 which might be a consequence of morphological k-correction effects.
We argue therefore that studies based on I-band HST/ACS classifications at
$z>1$ could be underestimating the elliptical population. [abridged]


title:
A Free Boundary Isoperimetric Problem in the Hyperbolic Space between
  parallel horospheres

abstract:
  In this work we investigate the following isoperimetric problem: to find the
regions of prescribed volume with minimal boundary area between two parallel
horospheres in hyperbolic 3-space (the area of the part of the boundary
contained in the horospheres is not included). We reduce the problem to the
study of rotationally invariant regions and obtain the possible isoperimetric
solutions by studying the behaviour of the profile curves of the rotational
surfaces with constant mean curvature in the hyperbolic space.


title: Introduction to the Minimal Model Program and the existence of flips

abstract:
  The first aim of this note is to give a concise, but complete and
self-contained, presentation of the fundamental theorems of Mori theory - the
nonvanishing, base point free, rationality and cone theorems - using modern
methods of multiplier ideals, Nadel vanishing, and the subadjunction theorem of
Kawamata. The second aim is to write up a complete, detailed proof of existence
of flips in dimension n assuming the minimal model program with scaling in
dimension n-1.


title: The noncommutative sine-Gordon breather

abstract:
  As shown in [hep-th/0406065], there exists a noncommutative deformation of
the sine-Gordon model which remains (classically) integrable but features a
second scalar field. We employ the dressing method (adapted to the
Moyal-deformed situation) for constructing the deformed kink-antikink and
breather configurations. Explicit results and plots are presented for the
leading noncommutativity correction to the breather. Its temporal periodicity
is unchanged.


title: Valence Bond States: Link models

abstract:
  An isotropic anti-ferromagnetic quantum state on a square lattice is
characterized by symmetry arguments only. By construction, this quantum state
is the result of an underlying valence bond structure without breaking any
symmetry in the lattice or spin spaces. A detailed analysis of the correlations
of the quantum state is given (using a mapping to a 2D classical statistical
model and methods in field theory like mapping to the non-linear sigma model or
bosonization techniques) as well as the results of numerical treatments
(regarding exact diagonalization and variational methods). Finally, the
physical relevance of the model is motivated. A comparison of the model to
known anti-ferromagnetic Mott-Hubbard insulators is given by means of the
two-point equal-time correlation function obtained i) numerically from the
suggested state and ii) experimentally from neutron scattering on cuprates in
the anti-ferromagnetic insulator phase.

categories: cond-mat.str-el cond-mat.stat-mech hep-th quant-ph


title: Bethe-Salpeter Equation -- The Origins

abstract:
  This article was originally written for scholarpedia.org. It describes the
origins and related background of Bethe-Salpeter equation.


title: Microdynamics in stationary complex networks

abstract:
  Many complex systems, including networks, are not static but can display
strong fluctuations at various time scales. Characterizing the dynamics in
complex networks is thus of the utmost importance in the understanding of these
networks and of the dynamical processes taking place on them. In this article,
we study the example of the US airport network in the time period 1990-2000. We
show that even if the statistical distributions of most indicators are
stationary, an intense activity takes place at the local (`microscopic') level,
with many disappearing/appearing connections (links) between airports. We find
that connections have a very broad distribution of lifetimes, and we introduce
a set of metrics to characterize the links' dynamics. We observe in particular
that the links which disappear have essentially the same properties as the ones
which appear, and that links which connect airports with very different traffic
are very volatile. Motivated by this empirical study, we propose a model of
dynamical networks, inspired from previous studies on firm growth, which
reproduces most of the empirical observations both for the stationary
statistical distributions and for the dynamical properties.


title: Toroidal Super-Heavy Nuclei in Skyrme-Hartree-Fock Approach

abstract:
  Within the self-consistent constraint Skyrme-Hartree-Fock+BCS model
(SHF+BCS), we found equilibrium toroidal nuclear density distributions in the
region of super-heavy elements. For nuclei with a sufficient oblate deformation
($Q_{20}\leq$ -200 b), it becomes energetically favourable to change the genus
of nuclear surface from 0 to 1, i.e., to switch the shape from a biconcave disc
to a torus. The energy of the toroidal (genus=1) SHF+BCS solution relative to
the compact (genus=0) ground state energy is strongly dependent both on the
atomic number Z and the mass number A. We discuss the region of Z and A where
the toroidal SHF+BCS total energy begins to be a global minimum.


title: Discovery of a Low-Mass Companion to the Solar-Type Star TYC 2534-698-1

abstract:
  Brown dwarfs and low-mass stellar companions are interesting objects to study
since they occupy the mass region between deuterium and hydrogen burning. We
report here the serendipitous discovery of a low-mass companion in an eccentric
orbit around a solar-type main sequence star. The stellar primary, TYC
2534-698-1, is a G2V star that was monitored both spectroscopically and
photometrically over the course of several months. Radial velocity observations
indicate a minimum mass of 0.037 M_solar and an orbital period of ~103 days for
the companion. Photometry outside of the transit window shows the star to be
stable to within ~6 millimags. The semi-major axis of the orbit places the
companion in the 'brown dwarf desert' and we discuss potential follow-up
observations that could constrain the mass of the companion.


title: Spectropolarimetry of Supernovae

abstract:
  Overwhelming evidence has accumulated in recent years that supernova
explosions are intrinsically 3-dimensional phenomena with significant
departures from spherical symmetry. We review the evidence derived from
spectropolarimetry that has established several key results: virtually all
supernovae are significantly aspherical near maximum light; core-collapse
supernovae behave differently than thermonuclear (Type Ia) supernovae; the
asphericity of core-collapse supernovae is stronger in the inner layers showing
that the explosion process itself is strongly aspherical; core-collapse
supernovae tend to establish a preferred direction of asymmetry; the
asphericity is stronger in the outer layers of thermonuclear supernovae
providing constraints on the burning process. We emphasize the utility of the
Q/U plane as a diagnostic tool and revisit SN 1987A and SN 1993J in a
contemporary context. An axially-symmetric geometry can explain many basic
features of core-collapse supernovae, but significant departures from axial
symmetry are needed to explain most events. We introduce a spectropolarimetry
type to classify the range of behavior observed in polarized supernovae.
Understanding asymmetries in supernovae is important for phenomena as diverse
as the origins of gamma-ray bursts and the cosmological applications of Type Ia
supernovae in studies of the dark energy content of the universe.


title: Improved lower bound on an Euclidean Ramsey problem

abstract:
  It was previously shown that any two-colour colouring of K(C_n) must contain
a monochromatic planar K_4 subgraph for n >= N^*, where 6 <= N^* <= N and N is
Graham's number. The bound was later improved to 11 <= N^* <= N. In this
article, it is improved to 13 <= N^* <= N.


title:
Resolution of two apparent paradoxes concerning quantum oscillations in
  underdoped high-$T_{c}$ superconductors

abstract:
  Recent quantum oscillation experiments in underdoped high temperature
superconductors seem to imply two paradoxes. The first paradox concerns the
apparent non-existence of the signature of the electron pockets in angle
resolved photoemission spectroscopy (ARPES). The second paradox is a clear
signature of a small electron pocket in quantum oscillation experiments, but no
evidence as yet of the corresponding hole pockets of approximately double the
frequency of the electron pocket. This hole pockets should be present if the
Fermi surface reconstruction is due to a commensurate density wave, assuming
that Luttinger sum rule relating the area of the pockets and the total number
of charge carriers holds. Here we provide possible resolutions of these
apparent paradoxes from the commensurate $d$-density wave theory. To address
the first paradox we have computed the ARPES spectral function subject to
correlated disorder, natural to a class of experiments relevant to the
materials studied in quantum oscillations. The intensity of the spectral
function is significantly reduced for the electron pockets for an intermediate
range of disorder correlation length, and typically less than half the hole
pocket is visible, mimicking Fermi arcs. Next we show from an exact transfer
matrix calculation of the Shubnikov-de Haas oscillation that the usual disorder
affects the electron pocket more significantly than the hole pocket. However,
when, in addition, the scattering from vortices in the mixed state is included,
it wipes out the frequency corresponding to the hole pocket. Thus, if we are
correct, it will be necessary to do measurements at higher magnetic fields and
even higher quality samples to recover the hole pocket frequency.


title:
Unconventional spin freezing and fluctuations in the frustrated
  antiferromagnet NiGa2S4

abstract:
  Muon spin rotation (muSR) experiments reveal unconventional spin freezing and
dynamics in the two-dimensional (2D) triangular lattice antiferromagnet
NiGa2S4. Long-lived disordered Ni-spin freezing (correlation time > 10-6 s at 2
K) sets in below T_f = 8.5 +- 0.5 K with a mean-field-like temperature
dependence. The observed exponential temperature dependence of the muon spin
relaxation above T_f is strong evidence for 2D critical spin fluctuations. Slow
Ni spin fluctuations coexist with quasistatic magnetism at low temperatures but
are rapidly suppressed for fields > 10 mT, in marked contrast with the
field-independent specific heat. The muSR and bulk susceptibility data indicate
a well-defined 2D phase transition at T_f, below which NiGa2S4 is neither a
conventional magnet nor a singlet spin liquid.


title: On dissociation of heavy mesons in a hot quark-gluon plasma

abstract:
  We compare two mechanisms for the dissociation of heavy mesons in an infinite
quark-gluon plasma: dynamic Debye screening and multiple scattering. Using the
uncertainty principle inspired by a Schrodinger-like equation, we find that the
criterion a_B\simeq1/\mu\simeq 1/(\alpha_{eff}^{1/2}T) with
\alpha_{eff}\equiv\alpha(N_c+{N_f\over2}) is parametrically true both for the
dissociation of fast moving heavy mesons with a size a_B due to dynamic Debye
screening as well as for mesons at rest in the medium. In contrast, we find
that the criterion for the dissociation of heavy mesons due to uncorrelated
multiple scattering is parametrically 1/a_B \simeq
[\gamma\alpha_{eff}\ln{1/\alpha_{eff}}]^{1/3}T. Therefore, multiple scattering
is a more efficient mechanism for the dissociation of heavy mesons in an
infinite hot plasma.


title:
The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies;
  Evolution and Lifetimes

abstract:
  (Abridged) The c2d Spitzer Legacy project obtained images and photometry with
both IRAC and MIPS instruments for five large, nearby molecular clouds. This
paper combines information drawn from studies of individual clouds into a
combined and updated statistical analysis of star formation rates and
efficiencies, numbers and lifetimes for SED classes, and clustering properties.
Current star formation efficiencies range from 3% to 6%. Taken together, the
five clouds are producing about 260 solar masses of stars per Myr. The star
formation surface density is more than an order of magnitude larger than would
be predicted from the Kennicutt relation used in extragalactic studies.
Measured against the dense gas probed by the maps of dust continuum emission,
the efficiencies are much higher, and the current stock of dense cores would be
exhausted in 1.8 Myr on average. The derived lifetime for the Class I phase is
0.44 to 0.54 Myr, considerably longer than some estimates. Similarly, the
lifetime for the Class 0 SED class, 0.10 to 0.16 Myr, is longer than early
estimates. The great majority (90%) of young stars lie within loose clusters
with at least 35 members and a stellar density of 1 solar mass per cubic pc.
Accretion at the sound speed from an isothermal sphere over the lifetime
derived for the Class I phase could build a star of about 0.25 solar masses,
given an efficiency of 0.3. Our data confirm and aggravate the "luminosity
problem" for protostars. Our results strongly suggest that accretion is time
variable, with prolonged periods of very low accretion. Based on a very simple
model and this sample of sources, half the mass of a star would be accreted
during only 7% of the Class I lifetime, as represented by the eight most
luminous objects.


title: Subnormal subalgebras of Leibniz algebras

abstract:
  Zassenhaus has proved that if U is a subnormal subalgebra of a
finite-dimensional Lie algebra L and V is a finite-dimensional irreducible
L-module, then all U-module composition factors of V are isomorphic. Schenkman
has proved that if U is a subnormal subalgebra of a finite-dimensional Lie
algebra L, then the nilpotent residual of U is an ideal of L. These useful
results generalise to Leibniz algebras.


title:
How to turn a scripting language into a domain specific language for
  computer algebra

abstract:
  We have developed two computer algebra systems, meditor [Jolly:2007] and JAS
[Kredel:2006]. These CAS systems are available as Java libraries. For the
use-case of interactively entering and manipulating mathematical expressions,
there is a need of a scripting front-end for our libraries. Most other CAS
invent and implement their own scripting interface for this purpose. We,
however, do not want to reinvent the wheel and propose to use a contemporary
scripting language with access to Java code. In this paper we discuss the
requirements for a scripting language in computer algebra and check whether the
languages Python, Ruby, Groovy and Scala meet these requirements. We conclude
that, with minor problems, any of these languages is suitable for our purpose.


title:
Top Quark Mass Measurement in the tt-bar All Hadronic Channel using a
  Matrix Element Technique in ppbar Collisions at sqrt s = 1.96 TeV

abstract:
  We present a measurement of the top quark mass in the all-hadronic channel
(\tt $\to$ \bb$q_{1}\bar{q_{2}}q_{3}\bar{q_{4}}$) using 943 pb$^{-1}$ of \ppbar
collisions at $\sqrt {s} = 1.96$ TeV collected at the CDF II detector at
Fermilab (CDF). We apply the standard model production and decay matrix-element
(ME) to $\ttbar$ candidate events. We calculate per-event probability densities
according to the ME calculation and construct template models of signal and
background. The scale of the jet energy is calibrated using additional
templates formed with the invariant mass of pairs of jets. These templates form
an overall likelihood function that depends on the top quark mass and on the
jet energy scale (JES). We estimate both by maximizing this function. Given 72
observed events, we measure a top quark mass of 171.1 $\pm$ 3.7 (stat.+JES)
$\pm$ 2.1 (syst.) GeV/$c^{2}$. The combined uncertainty on the top quark mass
is 4.3 GeV/$c^{2}$.


title: Heat kernel expansion in the covariant perturbation theory

abstract:
  Working within the framework of the covariant perturbation theory, we obtain
the coincidence limit of the heat kernel of an elliptic second order
differential operator that is applicable to a large class of quantum field
theories. The basis of tensor invariants of the curvatures of a gravity and
gauge field background, to the second order, is derived, and the form factors
acting on them are obtained in two integral representations. The results are
verified by the functional trace operation, by the short proper time
(Schwinger-DeWitt) expansions, as well as by the computation of the Green
function for the two-dimensional scalar field model.


title:
Transition from Pareto to Boltzmann-Gibbs behavior in a deterministic
  economic model

abstract:
  The one-dimensional deterministic economic model recently studied by
Gonzalez-Estevez et al. [Physica A 387, 4367 (2008)] is considered on a
two-dimensional square lattice with periodic boundary conditions. In this
model, the evolution of each agent is described by a map coupled with its
nearest neighbors. The map has two factors: a linear term that accounts for the
agent's own tendency to grow and an exponential term that saturates this growth
through the control effect of the environment. The regions in the parameter
space where the system displays Pareto and Boltzmann-Gibbs statistics are
calculated for the cases of von Neumann and of Moore's neighborhoods. It is
found that, even when the parameters in the system are kept fixed, a transition
from Pareto to Boltzmann-Gibbs behavior can occur when the number of neighbors
of each agent increases.

categories: q-fin.GN cond-mat.stat-mech nlin.AO physics.soc-ph


title:
Ground-state properties of interacting two-component Bose gases in a
  hard-wall trap

abstract:
  We investigate ground-state properties of interacting two-component Bose
gases in a hard-wall trap using both the Bethe ansatz and exact numerical
diagonalization method. For equal intra- and inter-atomic interaction, the
system is exactly solvable. Thus the exact ground state wavefunction and
density distributions for the whole interacting regime can be obtained from the
Bethe ansatz solutions. Since the ground state is a degenerate state with total
spin S=N/2, the total density distribution are same for each degenerate state.
The total density distribution evolves from a Gauss-like Bose distribution to a
Fermi-like one as the repulsive interaction increases. The distribution of each
component is N_i/N of the total density distribution. This is approximately
true even in the experimental situation. In addition the numerical results show
that with the increase of interspecies interaction the distributions of two
Tonks-Girardeau gases exhibit composite fermionization crossover with each
component developing N peaks in the strongly interacting regime.


title:
Radiative and non-perturbative corrections to the electron mass and the
  anomalous magnetic moment in the presence of an external magnetic field of
  arbitrary strength

abstract:
  Using the Ritus eingenfunction method we compute corrections to the electron
mass m_{0} in the presence of a moderate magnetic field eB ~ m_0^2. From this
we obtain an expression for the anomalous magnetic moment near the critic
field. For this we solved numerically the Schwinger-Dyson equations in the
rainbow approximation including all Landau levels without make any assumption
respect to the field strength.


title: Statistical ranking and combinatorial Hodge theory

abstract:
  We propose a number of techniques for obtaining a global ranking from data
that may be incomplete and imbalanced -- characteristics almost universal to
modern datasets coming from e-commerce and internet applications. We are
primarily interested in score or rating-based cardinal data. From raw ranking
data, we construct pairwise rankings, represented as edge flows on an
appropriate graph. Our statistical ranking method uses the graph Helmholtzian,
the graph theoretic analogue of the Helmholtz operator or vector Laplacian, in
much the same way the graph Laplacian is an analogue of the Laplace operator or
scalar Laplacian. We study the graph Helmholtzian using combinatorial Hodge
theory: we show that every edge flow representing pairwise ranking can be
resolved into two orthogonal components, a gradient flow that represents the
L2-optimal global ranking and a divergence-free flow (cyclic) that measures the
validity of the global ranking obtained -- if this is large, then the data does
not have a meaningful global ranking. This divergence-free flow can be further
decomposed orthogonally into a curl flow (locally cyclic) and a harmonic flow
(locally acyclic but globally cyclic); these provides information on whether
inconsistency arises locally or globally. An obvious advantage over the NP-hard
Kemeny optimization is that discrete Hodge decomposition may be computed via a
linear least squares regression. We also investigated the L1-projection of edge
flows, showing that this is dual to correlation maximization over bounded
divergence-free flows, and the L1-approximate sparse cyclic ranking, showing
that this is dual to correlation maximization over bounded curl-free flows. We
discuss relations with Kemeny optimization, Borda count, and Kendall-Smith
consistency index from social choice theory and statistics.


title:
X-Ray and high energy flares from late internal shocks of gamma-ray
  bursts

abstract:
  We study afterglow flares of gamma-ray bursts (GRBs) in the framework of the
late internal shock (LIS) model based on a careful description for the dynamics
of a pair of shocks generated by a collision between two homogeneous shells,.
First, by confronting the model with some fundamental observational features of
X-ray flares, we find some constraints on the properties of the pre-collision
shells that are directly determined by the central engine of GRBs. Second, high
energy emission associated with X-ray flares, which arises from synchrotron
self-Compton (SSC) emission of LISs, is investigated in a wide parameter space.
The predicted flux of high energy flares may reach as high as $\sim 10^{-8}\rm
erg cm^{-2}s^{-1}$, which is likely to be detectable with the Large Area
Telescope (LAT) aboard \textit{the Fermi Space Telescope}


title: Divisors on Rational Normal Scrolls

abstract:
  Let $A$ be the homogeneous coordinate ring of a rational normal scroll. The
ring $A$ is equal to the quotient of a polynomial ring $S$ by the ideal
generated by the two by two minors of a scroll matrix $\psi$ with two rows and
$\ell$ catalecticant blocks. The class group of $A$ is cyclic, and is infinite
provided $\ell$ is at least two. One generator of the class group is $[J]$,
where $J$ is the ideal of $A$ generated by the entries of the first column of
$\psi$. The positive powers of $J$ are well-understood, in the sense that the
$n^{\text{th}}$ ordinary power, the $n^{th}$ symmetric power, and the $n^{th}$
symbolic power all coincide and therefore all three $n^{th}$ powers are
resolved by a generalized Eagon-Northcott complex. The inverse of $[J]$ in the
class group of $A$ is $[K]$, where $K$ is the ideal generated by the entries of
the first row of $\psi$. We study the positive powers of $[K]$. We obtain a
minimal generating set and a Groebner basis for the preimage in $S$ of the
symbolic power $K^{(n)}$. We describe a filtration of $K^{(n)}$ in which all of
the factors are Cohen-Macaulay $S$-modules resolved by generalized
Eagon-Northcott complexes. We use this filtration to describe the modules in a
finely graded resolution of $K^{(n)}$ by free $S$-modules. We calculate the
regularity of the graded $S$-module $K^{(n)}$ and we show that the symbolic
Rees ring of $K$ is Noetherian.


title:
The Directional Dependence of the Lunar Cherenkov Technique for UHE
  Neutrino Detection

abstract:
  The LUNASKA (Lunar UHE Neutrino Astrophysics with the Square Kilometre Array)
project is a theoretical and experimental project developing the lunar
Cherenkov technique for the next generation of giant radio-telescope arrays.
This contribution presents our simulation results on the directional dependence
of the technique for UHE neutrino detection. In particular, these indicate that
both the instantaneous sensitivities and time-integrated limits from lunar
Cherenkov experiments such as those at Parkes, Goldstone, Kalyazin and ATCA are
highly anisotropic. We study the regions of the sky which have not been probed
by either these or other experiments, and present the expected sky coverage of
future experiments with the SKA. Our results show how the sensitivity of Lunar
Cherenkov observations to potential astrophysical sources of UHE particles may
be maximised by choosing appropriate observations dates and antenna-beam
pointing positions.


title: Non-Markovian Effects on the Geometric Phase

abstract:
  The geometric phases of a two-level atom interacting with non-Markovian
environments are calculated and the non-Markovian effects on the geometric
phases are discussed in this paper. Three kinds of methods that describe the
non-Markovian process, projection superoperator technique, memory kernel master
equation and post-Markovian master equation, are used in the discussions. The
results show that when the dissipation rate is large, the non-Markovian effects
change the geometric phase more strikingly than the small one.


title:
Status Report and Future Prospects on LUNASKA Lunar Observations with
  ATCA

abstract:
  LUNASKA (Lunar UHE Neutrino Astrophysics with the Square Kilometre Array) is
a theoretical and experimental project developing the lunar Cherenkov technique
for the next generation of giant radio-telescope arrays. Here we report on a
series of observations with ATCA (the Australia Telescope Compact Array). Our
current observations use three of the six 22m ATCA antennas with a 600 MHz
bandwidth at 1.2-1.8 GHz, analogue dedispersion filters to correct for the
typical night-time ionospheric dispersion, and state-of-the-art 2 GHz
FPGA-based digital pulse detection hardware. We have observed so as to maximise
the UHE neutrino sensitivity in the region surrounding the galactic centre and
to Centaurus A, to which current limits on the highest-energy neutrinos are
relatively weak.


title:
Calibration of photometry from the Gemini Multi-Object Spectrograph on
  Gemini North

abstract:
  All available observations of photometric standard stars obtained with the
Gemini Multi-Object Spectrograph at Gemini North in the period from August 2001
to December 2003 have been used to establish the calibrations for photometry
obtained with the instrument. The calibrations presented in this paper are
based on significantly more photometric standard star observations than usually
used by the individual users. Nightly photometric zero points as well as color
terms are determined. The color terms are expected to be valid for all
observations taken prior to UT 2004 November 21 at which time the Gemini North
primary mirror was coated with silver instead of aluminum. While the nightly
zero points are accurate to 0.02 mag or better (random errors), the accuracy of
the calibrations is limited by systematic errors from so-called "sky
concentration", an effect seen in all focal reducer instruments. We conclude
that an accuracy of 0.035 to 0.05 mag can be achieved by using calibrations
derived in this paper. The color terms are strongest for very red objects, e.g.
for objects with (r'-z')=3.0 the resulting z' magnitudes will be ~0.35 mag too
bright if the color term is ignored. The calibrations are of importance to the
large Gemini user community with data obtained prior to UT 2004 November 21, as
well as future users of achive data from this period in time.


title:
Magnetic Structure of Umbral Dots Observed with Hinode Solar Optical
  Telescope

abstract:
  High resolution and seeing-free spectroscopic observation of a decaying
sunspot was done with the Solar Optical Telescope aboard Hinode satellite. The
target was NOAA 10944 located in the west side of the solar surface from March
2 to March 4, 2007. The umbra included many umbral dots (UDs) with size of ~300
km in continuum light. We report the magnetic structures and Doppler velocity
fields around UDs, based on the Milne-Eddington inversion of the two iron
absorption lines at 6302 angstrom.
  The histograms of magnetic field strength(B), inclination angle(i), and
Doppler velocity(v) of UDs showed a center-to-limb variation. Observed at disk
center, UDs had (1)slightly smaller field strength (Delta B=-17 Gauss) and
(2)relative blue shifts (Delta v=28 m s-1) compared to their surroundings. When
the sunspot got close to the limb, UDs and their surroundings showed almost no
difference in the magnetic and Doppler values. This center-to-limb variation
can be understood by the formation height difference in a cusp-shaped
magnetized atmosphere around UDs, due to the weakly magnetized hot gas
intrusion. In addition, some UDs showed oscillatory light curves with multiple
peaks around 10 min, which may indicate the presence of the oscillatory
convection. We discuss our results in the frameworks of two theoretical models,
the monolithic model (Schussler & Vogler 2006) and the field-free intrusion
model (Spruit & Scharmer 2006).


title:
Resolution Trees with Lemmas: Resolution Refinements that Characterize
  DLL Algorithms with Clause Learning

abstract:
  Resolution refinements called w-resolution trees with lemmas (WRTL) and with
input lemmas (WRTI) are introduced. Dag-like resolution is equivalent to both
WRTL and WRTI when there is no regularity condition. For regular proofs, an
exponential separation between regular dag-like resolution and both regular
WRTL and regular WRTI is given.
  It is proved that DLL proof search algorithms that use clause learning based
on unit propagation can be polynomially simulated by regular WRTI. More
generally, non-greedy DLL algorithms with learning by unit propagation are
equivalent to regular WRTI. A general form of clause learning, called
DLL-Learn, is defined that is equivalent to regular WRTL.
  A variable extension method is used to give simulations of resolution by
regular WRTI, using a simplified form of proof trace extensions. DLL-Learn and
non-greedy DLL algorithms with learning by unit propagation can use variable
extensions to simulate general resolution without doing restarts.
  Finally, an exponential lower bound for WRTL where the lemmas are restricted
to short clauses is shown.