title:
Matter-Wave Solitons in the Presence of Collisional Inhomogeneities:
  Perturbation theory and the impact of derivative terms

abstract:
  We study the dynamics of bright and dark matter-wave solitons in the presence
of a spatially varying nonlinearity. When the spatial variation does not
involve zero crossings, a transformation is used to bring the problem to a
standard nonlinear Schrodinger form, but with two additional terms: an
effective potential one and a non-potential term. We illustrate how to apply
perturbation theory of dark and bright solitons to the transformed equations.
We develop the general case, but primarily focus on the non-standard special
case whereby the potential term vanishes, for an inverse square spatial
dependence of the nonlinearity. In both cases of repulsive and attractive
interactions, appropriate versions of the soliton perturbation theory are shown
to accurately describe the soliton dynamics.


title:
Wave turbulence on the surface of a ferrofluid submitted to a magnetic
  field

abstract:
  We report the observation of wave turbulence on the surface of a ferrofluid
mechanically forced and submitted to a static normal magnetic field. We show
that magnetic surface waves arise only above a critical field. The power
spectrum of their amplitudes displays a frequency-power law leading to the
observation of a magnetic wave turbulence regime which is experimentally shown
to involve a 4-wave interaction process. The existence of the regimes of
gravity, magnetic and capillary wave turbulence is reported in the phase space
parameters as well as a triple point of coexistence of these three regimes.
Most of these features are understood using dimensional analysis or the
dispersion relation of the ferrohydrodynamics surface waves.

categories: physics.class-ph cond-mat.stat-mech nlin.CD physics.flu-dyn


title: Small-scale instabilities in dynamical systems with sliding

abstract:
  We demonstrate with a minimal example that in Filippov systems (dynamical
systems governed by discontinuous but piecewise smooth vector fields) stable
periodic motion with sliding is not robust with respect to stable singular
perturbations. We consider a simple dynamical system that we assume to be a
quasi-static approximation of a higher-dimensional system containing a fast
stable subsystem. We tune a system parameter such that a stable periodic orbit
of the simple system touches the discontinuity surface: this is the so-called
grazing-sliding bifurcation. The periodic orbit remains stable, and its local
return map becomes piecewise linear. However, when we take into account the
fast dynamics the local return map of the periodic orbit changes qualitatively,
giving rise to, for example, period-adding cascades or small-scale chaos.


title:
Stochastic dynamics and mean field approach in a system of three
  interacting species

abstract:
  The spatio-temporal dynamics of three interacting species, two preys and one
predator, in the presence of two different kinds of noise sources is studied.
To describe the spatial distributions of the species we use a model based on
Lotka-Volterra equations. A correlated dichotomous noise acts on \beta, the
interaction parameter between the two preys, and a multiplicative white noise
affects directly the dynamics of each one of the three species. We study the
time behaviour of the three species in single site for different values of the
multiplicative noise intensity, finding noise-induced oscillations of the three
species densities with an anticorrelated behaviour of the two preys.
Afterwards, by considering a spatially extended system formed by a
two-dimensional lattice with N sites and applying a mean field approach, we get
the corresponding moment equations in Gaussian approximation. Within this
formalism we obtain the time behaviour of the first and second order moments
for different values of multiplicative noise intensity, with \beta(t) subject
to the same dichotomous noise source. Finally, we compare our results with
those obtained by using a coupled map lattice model, consisting of a time
discrete version of the Lotka-Volterra equations.


title: On right-angled Artin groups without surface subgroups

abstract:
  We study the class N of graphs, the right-angled Artin groups defined on
which do not contain surface subgroups. We prove that a presumably smaller
class N' is closed under amalgamating along complete subgraphs, and also under
adding bisimplicial edges. It follows that chordal graphs and chordal bipartite
graphs belong to N'.


title:
Pilotage des processus collaboratifs dans les syst\`emes PLM. Quels
  indicateurs pour quelle \'evaluation des performances ?

abstract:
  Les entreprises qui collaborent dans un processus de d\'eveloppement de
produit ont besoin de mettre en oeuvre une gestion efficace des activit\'es
collaborative. Malgr\'e la mise en place d'un PLM, les activit\'es
collaborative sont loin d'\^etre aussi efficace que l'on pourrait s'y attendre.
Cet article propose une analyse des probl\'ematiques de la collaboration avec
un syst\`eme PLM. A partir de ces analyses, nous proposons la mise en place
d'indicateurs et d'actions sur les processus visant \`a identifier puis
att\'enuer les freins dans le travail collaboratif. ----- Companies that
collaborate within the product development processes need to implement an
effective management of their collaborative activities. Despite the
implementation of a PLM system, the collaborative activities are not efficient
as it might be expected. This paper presents an analysis of the problems
related to the collaborative work using a PLM system, identified through a
survey. From this analysis, we propose an approach for improving collaborative
processes within a PLM system, based on monitoring indicators. This approach
leads to identify and therefore to mitigate the brakes of the collaborative
work.


title:
Exact solutions in the Dirac-Born-Infeld effective theory and the fate
  of tachyon

abstract:
  We show that the equation of motion from the Dirac-Born-Infeld effective
action of a general scalar field with some specific potentials admits exact
solutions after appropriate field redefinitions. Based on the exact solutions
and their energy-momentum tensors, we find that massive scalars and massless
scalars of oscillating modes in the DBI effective theory are not pressureless
generically for any possible momenta, which implies that the pressureless
"tachyon matter" forming at late time of the tachyon condensation process
should not really be some massive matter. It is more likely that the tachyon
field at late time behaves as a massless scalar of zero modes. At kinks, the
tachyon can be viewed as a massless scalar of a translational zero mode
describing a stable and static D-brane with one dimension lower. Near the
vacuum, the tachyon in regions without the caustic singularities can be viewed
as a massless scalar that has the same zero mode solution as a fundamental
string moving with a critical velocity. We find supporting evidences to this
conclusion by considering a DBI theory with modified tachyon potential, in
which the development of caustics near the vacuum may be avoided.


title: Moduli Spaces of Semistable Sheaves on Projective Deligne-Mumford Stacks

abstract:
  We introduce a notion of Gieseker stability for coherent sheaves on tame
Deligne-Mumford stacks with projective moduli scheme and some chosen generating
sheaf on the stack in the sense of Olsson and Starr \cite{MR2007396}. We prove
that this stability condition is open, and pure dimensional semistable sheaves
form a bounded family. We explicitly construct the moduli stack of semistable
sheaves as a finite type global quotient, and study the moduli scheme of stable
sheaves and its natural compactification in the same spirit as the seminal
paper of Simpson \cite{MR1307297}. With this general machinery we are able to
retrieve, as special cases, results of Lieblich \cite{MR2309155} and Yoshioka
\cite{MR2306170} about moduli of twisted sheaves and parabolic stability
introduced by Maruyama-Yokogawa in \cite{MR1162674}.


title:
Collaborative process control: Observation of tracks generated by PLM
  system

abstract:
  This paper aims at analyzing the problems related to collaborative work using
a PLM system. This research is mainly focused on the organisational aspects of
SMEs involved in networks composed of large companies, subcontractors and other
industrial partners. From this analysis, we propose the deployment of an
approach based on an observation process of tracks generated by PLM system. The
specific contributions are of two fold. First is to identify the brake points
of collaborative work. The second, thanks to the exploitation of generated
tracks, it allows reducing risks by reacting in real time to the incidents or
dysfunctions that may occur. The overall system architecture based on services
technology and supporting the proposed approach is described, as well as
associated prototype developed using an industrial PLM system.


title: Asymptotic behavior of self-affine processes in semi-infinite domains

abstract:
  We propose to model the stochastic dynamics of a polymer passing through a
pore (translocation) by means of a fractional Brownian motion, and study its
behavior in presence of an absorbing boundary. Based on scaling arguments and
numerical simulations, we present a conjecture that provides a link between the
persistence exponent $\theta$ and the Hurst exponent $H$ of the process, thus
sheding light on the spatial and temporal features of translocation.
Furthermore, we show that this conjecture applies more generally to a broad
class of self affine processes undergoing anomalous diffusion in bounded
domains, and we discuss some significant examples.


title: Fibrations and fundamental groups of Kaehler-Weyl manifolds

abstract:
  We extend the Siu--Beauville theorem to a certain class of compact
Kaehler--Weyl manifolds, proving that they fiber holomorphically over
hyperbolic Riemannian surfaces whenever they satisfy the necessary topological
hypotheses. As applications we obtain restrictions on the fundamental groups of
such Kaehler--Weyl manifolds, and show that in certain cases they are in fact
Kaehler.


title: St\"uckelino Dark Matter in Anomalous U(1)' Models

abstract:
  We study a possible dark matter candidate in the framework of a minimal
anomalous $U(1)'$ extension of the MSSM. It turns out that in a suitable
decoupling limit the St\"uckelino, the fermionic degree of freedom of the
St\"uckelberg multiplet, is the lightest supersymmetric particle (LSP). We
compute the relic density of this particle including coannihilations with the
next to lightest supersymmetric particle (NLSP) and with the next to next to
lightest supersymmetric particle (NNLSP) which are assumed almost degenerate in
mass. This assumption is needed in order to satisfy the stringent limits that
the Wilkinson Microwave Anisotropy Probe (WMAP) puts on the relic density. We
find that the WMAP constraints can be satisifed by different NLSP and NNLSP
configurations as a function of the mass gap with the LSP. These results hold
in the parameter space region where the model remains perturbative.


title: High Energy Studies of Pulsar Wind Nebulae

abstract:
  The extended nebulae formed as pulsar winds expand into their surroundings
provide information about the composition of the winds, the injection history
from the host pulsar, and the material into which the nebulae are expanding.
Observations from across the electromagnetic spectrum provide constraints on
the evolution of the nebulae, the density and composition of the surrounding
ejecta, the geometry of the systems, the formation of jets, and the maximum
energy of the particles in the nebulae. Here I provide a broad overview of the
structure of pulsar wind nebulae, with specific examples that demonstrate our
ability to constrain the above parameters. The association of pulsar wind
nebulae with extended sources of very high energy gamma-ray emission are
investigated, along with constraints on the nature of such high energy
emission.


title: Grothendieck Duality for Deligne-Mumford Stacks

abstract:
  We prove the existence of the dualizing functor for a separated morphism of
algebraic stacks with affine diagonal; then we explicitly develop duality for
compact Deligne-Mumford stacks focusing in particular on the morphism from a
stack to its coarse moduli space and on representable morphisms. We explicitly
compute the dualizing complex for a smooth stack over an algebraically closed
field and prove that Serre duality holds for smooth compact Deligne-Mumford
stacks in its usual form. We prove also that a proper Cohen-Macaulay stack has
a dualizing sheaf and it is an invertible sheaf when it is Gorenstein. As an
application of this general machinery we compute the dualizing sheaf of a tame
nodal curve.


title:
Spin-Dynamics of the antiferromagnetic S=1/2-Chain at finite magnetic
  Fields and intermediate Temperatures

abstract:
  We present a study of the dynamic structure factor of the antiferromagnetic
spin-1/2 Heisenberg chain at finite temperatures and finite magnetic fields.
Using Quantum-Monte-Carlo based on the stochastic series expansion and
Maximum-Entropy methods we evaluate the longitudinal and the transverse dynamic
structure factor from vanishing magnetic fields up to and above the threshold
$B_c$ for ferromagnetic saturation, as well as for high and for intermediate
temperatures. We study the field-induced redistribution of spectral weight
contrasting longitudinal versus transverse excitations. At finite fields below
saturation incommensurate low-energy modes are found consistent with zero
temperature Bethe-Ansatz. The crossover between the field induced ferromagnet
above $B_c$ and the Luttinger liquid below $B_c$ is analyzed in terms of the
transverse spin-dynamics. Evaluating sum-rules we assess the quality of the
analytic continuation and demonstrate excellent consistency of the
Maximum-Entropy results.


title: Disformal quintessence

abstract:
  A canonic scalar field minimally coupled to a disformal metric generated by
the field itself is considered. Causality and stability conditions are derived
for such a field. Cosmological effects are studied and it is shown that the
disformal modification could viably trigger an acceleration after a scaling
matter era, thus possibly alleviating the coincidence problem.


title: The accretion regime of LS 5039: 3-D SPH simulations

abstract:
  LS 5039 is a TeV gamma-ray binary with extended radio emission. It consists
of a compact object in the mildly eccentric (e=0.35), 3.9-day orbit around a
massive O star. The nature of the compact object is not yet established. In
this paper, assuming that the compact object is a black hole, we study the
accretion of O-star wind by the black hole, by performing three-dimensional
Smoothed Particle Hydrodynamics (SPH) simulations. In order to roughly emulate
the effect of the stellar radiation effectively canceling the stellar gravity,
we assume that the O star's gravity does not exert on the wind. The wind
particles are ejected with half the observed terminal velocity in a narrow
range of azimuthal and vertical angles toward the black hole, in order to
emulate the wind significantly slower than the terminal speed, and optimize the
resolution and computational efficiency of simulations. We find that the
mass-accretion rate closely follows the classical Bondi-Hoyle-Littleton
accretion rate, which is of the order of 10^{16}g/s around periastron. The
accretion rate at this level would provide jets enough power to produce the
gamma-rays detected by HESS. Since the accretion peak occurs near the
periastron passage, we need a strong gamma-ray absorption around periastron in
order for the microquasar scenario to be consistent with the observed orbital
modulation of the TeV gamma-ray flux.


title:
Characterization and collection of information from heterogeneous
  multimedia sources with users' parameters for decision support

abstract:
  No single information source can be good enough to satisfy the divergent and
dynamic needs of users all the time. Integrating information from divergent
sources can be a solution to deficiencies in information content. We present
how Information from multimedia document can be collected based on associating
a generic database to a federated database. Information collected in this way
is brought into relevance by integrating the parameters of usage and user's
parameter for decision making. We identified seven different classifications of
multimedia document.


title: Exploring high-intensity QED at ELI

abstract:
  We give a non-technical overview of QED effects arising in the presence of
ultra-strong electromagnetic fields highlighting the new prospects provided by
a realisation of the ELI laser facility.


title:
Enhancement of quasiparticle recombination in Ta and Al superconductors
  by implantation of magnetic and nonmagnetic atoms

abstract:
  The quasiparticle recombination time in superconducting films, consisting of
the standard electron-phonon interaction and a yet to be identified low
temperature process, is studied for different densities of magnetic and
nonmagnetic atoms. For both Ta and Al, implanted with Mn, Ta and Al, we observe
an increase of the recombination rate. We conclude that the enhancement of
recombination is not due to the magnetic moment, but arises from an enhancement
of disorder.


title:
Timelike Geodesic Currents in the Stationary, Axisymmetric, Force-free
  Magnetosphere of a Kerr Black Hole

abstract:
  The structural properties of geodesic currents in an ambient Kerr background
is studied from an analytical point of view. The geodesics in the congruence
correspond to charged particles that carry energy and angular momentum from the
black hole through the Blandford-Znajek mechanism. It is shown that the
resulting magnetosphere naturally satisfies the Znajek regularity condition.
Particular attention is paid here to the energy extracted by matter currents
rather than by electromagnetic Poynting fluxes.


title:
A d-bar-theoretical proof of Hartogs' extension theorem on
  (n-1)-complete spaces

abstract:
  Let X be a connected normal complex space of dimension n>=2 which is
(n-1)-complete, and let p: M -> X be a resolution of singularities. By use of
Takegoshi's generalization of the Grauert-Riemenschneider vanishing theorem, we
deduce H^1_{cpt}(M,O)=0, which in turn implies Hartogs' extension theorem on X
by the d-bar-technique of Ehrenpreis.


title: Dynamical simulation of lattice 4d N=1 SYM

abstract:
  The lattice provides a powerful tool to non-perturbatively investigate
strongly coupled supersymmetric Yang-Mills (SYM) theories. The pure SU(2) SYM
theory with one supercharge is simulated on large lattices with small Majorana
gluino masses down to about $am_{\tilde g}=0.068$ with lattice spacing $a\simeq
0.125$ fm. The gluino dynamics is simulated by the Two-Step Multi-Boson (TSMB)
and the Two-Step Polynomial Hybrid Monte Carlo (TS-PHMC) algorithms.
Supersymmetry (SUSY) is broken explicitly by the lattice and the Wilson term
and softly by the presence of a non-vanishing gluino mass. However, the
recovery of SUSY is expected in the infinite volume continuum limit by tuning
the bare parameters to the SUSY point in the parameter space. This scenario is
studied by the determination of the low-energy mass spectrum and by means of
lattice SUSY Ward-Identities (WIs).


title: W_{N+1}-constraints for singularities of type A_N

abstract:
  Using Picard--Lefschetz periods for the singularity of type $A_N$, we
construct a projective representation of the Lie algebra of differential
operators on the circle with central charge $h:=N+1$. We prove that the total
descendant potential $\D_{A_N}$ of $A_N$-singularity is a highest weight
vector. It is known that $\D_{A_N}$ can be interpreted as a generating function
of a certain class of intersection numbers on the moduli space of $h$-spin
curves. In this settings our constraints provide a complete set of recursion
relations between the intersection numbers. Our methods are based entirely on
the symplectic loop space formalism of A. Givental and therefore they can be
applied to the mirror models of symplectic manifolds.


title: Quasi-convex sequences in the circle and the 3-adic integers

abstract:
  In this paper, we present families of quasi-convex sequences converging to
zero in the circle group T, and the group J_3 of 3-adic integers. These
sequences are determined by an increasing sequences of integers. For an
increasing sequence \underline{a}=\{a_n\} of integers, put g_n=a_{n+1}-a_n. We
prove that:
  (a) the set \{0\}\cup\{\pm 3^{-(a_n+1)} : n\in N\} is quasi-convex in T if
and only if a_0>0 and g_n>1 for every n\in N;
  (b) the set \{0\}\cup\{\pm 3^{a_n} : n\in N\} is quasi-convex in the group
J_3 of 3-adic integers if and only if g_n>1 for every n\in N.
  Moreover, we solve an open problem of Dikranjan and de Leo by providing a
complete characterization of the sequences \underline{a} such that
\{0\}\cup\{\pm 2^{-(a_n+1)} : n\in N\} is quasi-convex in T. Using this result,
we also obtain a characterization of the sequences \underline{a} such that the
set \{0\}\cup\{\pm 2^{-(a_n+1)} : n\in N\} is quasi-convex in R.


title: Quantum scale invariance on the lattice

abstract:
  We propose a scheme leading to a non-perturbative definition of lattice field
theories which are scale-invariant on the quantum level. A key idea of the
construction is the replacement of the lattice spacing by a propagating
dynamical field -- the dilaton. We describe how to select non-perturbatively
the phenomenologically viable theories where the scale invariance is broken
spontaneously. Relation to gravity is also discussed.


title:
Entanglement entropy for a Dirac fermion in three dimensions: vertex
  contribution

abstract:
  In three dimensions there is a logarithmically divergent contribution to the
entanglement entropy which is due to the vertices located at the boundary of
the region considered. In this work we find the corresponding universal
coefficient for a free Dirac field, and extend a previous work in which the
scalar case was treated. The problem is equivalent to find the conformal
anomaly in three dimensional space where multiplicative boundary conditions for
the field are imposed on a plane angular sector. As an intermediate step of the
calculation we compute the trace of the Green function of a massive Dirac field
in a two dimensional sphere with boundary conditions imposed on a segment of a
great circle.


title: The Index of Hypoelliptic Operators on Foliated Manifolds

abstract:
  We present an index theorem for certain hypoelliptic differential operators
on foliated manifolds. Our proof is a development of Alain Connes tangent
groupoid proof of the Atiyah-Singer index theorem. The paper is largely
self-contained.


title: Mathieu functions computational toolbox implemented in Matlab

abstract:
  The Mathieu functions are used to solve analytically some problems in
elliptical cylinder coordinates. A computational toolbox was implemented in
Matlab. Since the notation and normalization for Mathieu functions vary in the
literature, we have included sufficient material to make this presentation self
contained. Thus, all formulas required to get the Mathieu functions are given
explicitly. Following the outlines in this presentation, the Mathieu functions
could be readily implemented in other computer programs and used in different
domains. Tables of numerical values are provided.


title: New views on bar pattern speeds from the NUGA survey

abstract:
  We present a review on bar pattern speeds from preliminary results in the
context of the Nuclei of Galaxies (NUGA) project. The large variety of
molecular circumnuclear morphologies found in NUGA is a challenging result that
implies the refinement of current dynamical models of galaxies.


title: GCRT J1742-3001: A New Radio Transient Towards the Galactic Center

abstract:
  We report the detection of a new transient radio source, GCRT J1742-3001,
located ~1 degree from the Galactic center. The source was detected ten times
from late 2006 to 2007 May in our 235 MHz transient monitoring program with the
Giant Metrewave Radio Telescope (GMRT). The radio emission brightened in about
one month, reaching a peak observed flux density of ~100 mJy on 2007 January
28, and decaying to ~50 mJy by 2007 May when our last monitoring observation
was made. Two additional faint, isolated 235 MHz detections were made in
mid-2006, also with the GMRT. GCRT J1742-3001 is unresolved at each epoch, with
typical resolutions of ~20 arcsec x 10 arcsec. No polarization information is
available from the observations. Based on nondetections in observations
obtained simultaneously at 610 MHz, we deduce that the spectrum of GCRT
J1742-3001 is very steep, with a spectral index less than about -2. Follow-up
radio observations in 2007 September at 330 MHz and 1.4 GHz, and in 2008
February at 235 MHz yielded no detections. No X-ray counterpart is detected in
a serendipitous observation obtained with the X-ray telescope aboard the Swift
satellite during the peak of the radio emission in early 2007. We consider the
possibilities that GCRT J1742-3001 is either a new member of an existing class
of radio transients, or is representative of a new class having no associated
X-ray emission.


title:
Fishing in Tidal Streams: New Radial Velocity and Proper Motion
  Constraints on the Orbit of the Anticenter Stream

abstract:
  We have obtained radial velocity measurements for stars in two,
widely-separated fields in the Anticenter Stream. Combined with SDSS/USNO-B
proper motions, the new measurements allow us to establish that the stream is
on a nearly circular, somewhat inclined, prograde orbit around the Galaxy.
While the orbital eccentricity is similar to that previously determined for the
Monoceros stream, the sizes, inclinations, and positions of the orbits for the
two systems differ significantly. Integrating our best fitting Anticenter
Stream orbit forward, we find that it is closely aligned along and lies almost
on top of a stream-like feature previously designated the "Eastern Banded
Structure". The position of this feature coincides with the apogalacticon of
the orbit. We tentatively conclude that this feature is the next wrap of the
Anticenter Stream.


title: Magic Fairy Tales as Source for Interface Metaphors

abstract:
  The work is devoted to a problem of search of metaphors for interactive
systems and systems based on Virtual Reality (VR) environments. The analysis of
magic fairy tales as a source of metaphors for interface and virtual reality is
offered. Some results of design process based on magic metaphors are
considered.


title: Pulse Areas in Multi-Soliton Propagation

abstract:
  The prospect of self-consistent propagation of more than two pulses
contemporaneously through multi-resonant media raises open questions: whether
soliton solutions exist, and whether a useful generalization of two-level pulse
Area can be found. We answer these questions positively for the case of four
pulses interacting in combined V and Lambda fashion with an idealized pair of
atomic D-lines.


title: Coalgebraic Automata Theory: Basic Results

abstract:
  We generalize some of the central results in automata theory to the
abstraction level of coalgebras and thus lay out the foundations of a universal
theory of automata operating on infinite objects.
  Let F be any set functor that preserves weak pullbacks. We show that the
class of recognizable languages of F-coalgebras is closed under taking unions,
intersections, and projections. We also prove that if a nondeterministic
F-automaton accepts some coalgebra it accepts a finite one of the size of the
automaton. Our main technical result concerns an explicit construction which
transforms a given alternating F-automaton into an equivalent nondeterministic
one, whose size is exponentially bound by the size of the original automaton.


title:
Power Spectra in a Zero-Range Process on a Ring: Total Occupation Number
  in a Segment

abstract:
  We study the dynamics of density fluctuations in the steady state of a
non-equilibrium system, the Zero-Range Process on a ring lattice. Measuring the
time series of the total number of particles in a \emph{segment} of the
lattice, we find remarkable structures in the associated power spectra, namely,
two distinct components of damped-oscillations. The essential origin of both
components is shown in a simple pedagogical model. Using a more sophisticated
theory, with an effective drift-diffusion equation governing the stochastic
evolution of the local particle density, we provide reasonably good fits to the
simulation results. The effects of altering various parameters are explored in
detail. Avenues for improving this theory and deeper understanding of the role
of particle interactions are indicated.


title: Homomorphisms of infinitely generated analytic sheaves

abstract:
  We prove that every homomorphism $\mathcal{O}^E_\zeta\to\mathcal{O}^F_\zeta$,
with $E$ and $F$ Banach spaces and $\zeta\in\mathbb{C}^m$, is induced by a
$\mathop{\mathrm{Hom}}(E,F)$-valued holomorphic germ, provided that $1\leq
m<\infty$. A similar structure theorem is obtained for the homomorphisms of
type $\mathcal{O}^E_\zeta\to\mathcal{S}_\zeta$, where $\mathcal{S}_\zeta$ is a
stalk of a coherent sheaf of positive $\mathfrak{m}_\zeta$-depth. We later
extend these results to sheaf homomorphisms, obtaining a condition on coherent
sheaves which guarantees the sheaf to be equipped with a unique analytic
structure in the sense of Lempert-Patyi.


title: Search for the decay B^+ --> K_S^0 K_S^0 pi^+

abstract:
  We search for charmless decays of charged B mesons to the three-body final
state K_S^0 K_S^0 pi+. Using a data sample of 423.7 fb^-1 collected at the
Upsilon(4S) resonance with the BABAR detector, corresponding to (465.1 +-
5.1)X10^6 BB-bar pairs, we find no significant signal and determine a 90%
confidence level upper limit on the branching fraction of 5.1X10^-7.


title: Identification and characterization of icosahedral metallic nanowires

abstract:
  We present and discuss an algorithm to identify and characterize the long
icosahedral structures (staggered pentagonal nanowires with 1-5-1-5 atomic
structure) that appear in Molecular Dynamics simulations of metallic nanowires
of different species subjected to stretching. The use of the algorithm allows
the identification of pentagonal rings forming the icosahedral structure as
well as the determination of its number, and the maximum length of the
pentagonal nanowire. The algorithm is tested with some ideal structures to show
its ability to discriminate between pentagonal rings and other ring structures.
We applied the algorithm to Ni nanowires with temperatures ranging between 4K
and 865K, stretched along the [100] direction. We studied statistically the
formation of pentagonal nanowires obtaining the distributions of the maximum
length and number of rings as function of the temperature. The pentagonal
nanowire maximum length distribution presents a peaked shape, with peaks locate
at fixes distances whose separa-tion corresponds to the distance between two
consecutive pentagonal rings.


title: Long period planets from dynamical relaxation

abstract:
  Recent imaging campaigns indicate the likely existence of massive planets (~
1-10 MJ) on ~1000 year orbits about a few percent of stars. Such objects are
not easily explained in most current planet formation models. In this Letter we
use ensembles of 100 N-body simulations to evaluate the potential for planet
scattering during relaxation of dynamically active systems to explain the
population of giant planets with projected separations up to a few 100 AU. We
find that such a mechanism could indeed be at play, and that statistical
samples of long period planets could place interesting constraints on early
stage planet formation scenarios. Results from direct imaging and microlensing
surveys are complementary probes of this dynamical relaxation process.


title: Ab initio determination of ion-traps in silver-doped chalcogenide glass

abstract:
  We present a microscopic picture of silver dynamics in GeSe$_{3}$:Ag glass
obtained from {\it ab initio} simulation. The dynamics of Ag is explored at two
temperatures, 300K and 700K. In the relaxed network, Ag occupies bond centers
between suitably separated host sites. At 700K, Ag motion proceeds via a
trapping-release dynamics, between "super traps" or cages consisting of
multiple bond-center sites in a small volume. Our work offers a first
principles identification of trapping centers invoked in current theories, with
a description of their properties. We compute the charge state of the Ag in the
network, and show that it is neutral if weakly bonded and Ag$^+$ if in a
trapping center.


title: Differential posets and Smith normal forms

abstract:
  We conjecture a strong property for the up and down maps U and D in an
r-differential poset: DU+tI and UD+tI have Smith normal forms over Z[t]. In
particular, this would determine the integral structure of the maps U, D, UD,
DU, including their ranks in any characteristic.
  As evidence, we prove the conjecture for the Young-Fibonacci lattice YF
studied by Okada and its r-differential generalizations Z(r), as well as
verifying many of its consequences for Young's lattice Y and the r-differential
Cartesian products Y^r.


title: Modeling Gamma-Ray Attenuation in High-Redshift GeV Spectra

abstract:
  We present two models for the cosmological UV background light, and calculate
the opacity of GeV gamma--rays out to redshift 9. The contributors to the
background include 2 possible quasar emissivities, and output from
star--forming galaxies as determined by recent a semi--analytic model (SAM) of
structure formation. The SAM used in this work is based upon a hierarchical
build-up of structure in a $\Lambda$CDM universe and is highly successful in
reproducing a variety of observational parameters. Above 1 Rydberg energy,
ionizing radiation is subject to reprocessing by the IGM, which we treat using
our radiative transfer code, CUBA. The two models for quasar emissivity
differing above z = 2.3 are chosen to match the ionization rates observed using
flux decrement analysis and the higher values of the line-of-sight proximity
effect. We also investigate the possibility of a flat star formation rate
density at z $>5$. We conclude that observations of gamma--rays from 10 to 100
GeV by Fermi (GLAST) and the next generation of ground based experiments should
confirm a strongly evolving opacity from $1<$ z $<4$. Observation of
attenuation in the spectra of gamma--ray bursts at higher redshift could
constrain emission of UV radiation at these early times, either from a flat or
increasing star-formation density or an unobserved population of sources.


title:
Fomalhaut's Debris Disk and Planet: Constraining the Mass of Fomalhaut b
  From Disk Morphology

abstract:
  Following the optical imaging of the exoplanet candidate Fomalhaut b (Fom b),
we present a numerical model of how Fomalhaut's debris disk is gravitationally
shaped by an interior planet. The model is simple, adaptable to other debris
disks, and can be extended to accommodate multiple planets. If Fom b is the
dominant perturber of the belt, then to produce the observed disk morphology it
must have a mass < 3 Jupiter masses. If the belt and planet orbits are
apsidally aligned, our model predicts a planet mass of 0.5 Jupiter masses. The
inner edge of the debris disk at 133 AU lies at the periphery of Fom b's
chaotic zone, and the mean disk eccentricity of 0.11 is secularly forced by the
planet, supporting predictions made prior to the discovery of Fom b. However,
previous mass constraints based on disk morphology rely on several
oversimplifications. We explain why our constraint is more reliable. It is
based on a global model of the disk that is not restricted to the planet's
chaotic zone boundary. Moreover, we screen disk parent bodies for dynamical
stability over the system age of 100 Myr, and model them separately from their
dust grain progeny; the latter's orbits are strongly affected by radiation
pressure and their lifetimes are limited to 0.1 Myr by destructive grain-grain
collisions. The single planet model predicts that planet and disk orbits be
apsidally aligned. Fom b's nominal space velocity does not bear this out, but
the astrometric uncertainties may be large. If the apsidal misalignment is
real, our upper mass limit of 3 Jupiter masses still holds. The belt contains
at least 3 Earth masses of solids that are grinding down to dust. Such a large
mass in solids is consistent with Fom b having formed in situ.


title:
The Ellipticities of Cluster Early-type Galaxies from z~1 to z~0: No
  Evolution in the Overall Distribution of Bulge-to-Disk Ratios

abstract:
  We have compiled a sample of early-type cluster galaxies from 0 < z < 1.3 and
measured the evolution of their ellipticity distributions. Our sample contains
487 galaxies in 17 z>0.3 clusters with high quality space-based imaging and a
comparable sample of 210 galaxies in 10 clusters at z<0.05. We select
early-type galaxies (elliptical and S0 galaxies) that fall within the cluster
R_{200}, and which lie on the red-sequence in the magnitude range -19.3 > M_B >
-21, after correcting for luminosity evolution. Our ellipticity measurements
are made in a consistent manner over our whole sample. We perform extensive
simulations to quantify the systematic and statistical errors, and find that it
is crucial to use PSF-corrected model fits. We find that neither the median
ellipticity, nor the shape of the ellipticity distribution of cluster
early-type galaxies evolves with redshift from z ~ 0 to z > 1. These results
are strongly suggestive of an unchanging overall bulge-to-disk ratio
distribution for cluster early-type galaxies over the last ~8Gyr. This result
contrasts with that from visual classifications which show that the fraction of
morphologically-selected disk-dominated early-type galaxies, or S0s, is
significantly lower at z>0.4 than at z~0. Taking the ellipticity measurements
and assuming, as in all previous studies, that the intrinsic ellipticity
distribution of both elliptical and S0 galaxies remains constant, then we
conclude from the lack of evolution in the observed early-type ellipticity
distribution that the relative fractions of ellipticals and S0s do not evolve
from z~1 to z=0 for a red-sequence selected samples of galaxies in the cores of
clusters of galaxies.


title:
Bino-driven Electroweak Baryogenesis with highly suppressed Electric
  Dipole Moments

abstract:
  It is conventional wisdom that successful electroweak baryogenesis in the
Minimal Supersymmetric extension of the Standard Model (MSSM) is in tension
with the non-observation of electric dipole moments (EDMs), since the level of
CP-violation responsible for electroweak baryogenesis is believed to generate
unavoidably large EDMs. We show that CP-violation in the bino-Higgsino sector
of the MSSM can account for successful electroweak baryogenesis without
inducing large EDMs. This observation weakens the correlation between
electroweak baryogenesis and EDMs, and makes the bino-driven electroweak
baryogenesis scenario the least constrained by EDM limits. Taking this
observation together with the requirement of a strongly first-order electroweak
phase transition, we argue that a bino-driven scenario with a light stop is the
most phenomenologically viable MSSM electroweak baryogenesis scenario.


title:
Dynamical Evolution of AGN Host Galaxies - Gas In/Out-Flow Rates in 7
  NUGA Galaxies

abstract:
  To examine the role of the host galaxy structure in fueling nuclear activity,
we estimated gas flow rates from several kpc down to the inner few 10 pc for
seven nearby spiral galaxies, selected from the NUGA sample (NUclei of
GAlaxies). We calculated gravitational torques from near-IR images and
determined gas in/out-flow rates as a function of radius and location within
the galactic disks, based on high angular resolution interferometric
observations of molecular (CO using PdBI) and atomic (HI using the VLA) gas.
The results are compared with kinematic evidence for radial gas flows and the
dynamical state of the galaxies (via resonances) derived from several different
methods. We show that gravitational torques are very efficient at transporting
gas from the outer disk all the way into the galaxies centers at ~100 pc;
previously assumed dynamical barriers to gas transport, such as the Corotation
Resonance of stellar bars, seem to be overcome by gravitational torque induced
gas flows from other non-axisymmmetric structures. The resulting rates of gas
mass inflow range from 0.01 to 50 solar masses per year and are larger for the
galaxy center than for the outer disk. Our gas flow maps show the action of
nested bars within larger bars for 3 galaxies. Non-circular streaming motions
found in the kinematic maps are larger in the center than in the outer disk and
appear to correlate only loosely with the in/out-flow rates as a function of
radius. We demonstrate that spiral gas disks are very dynamic systems that
undergo strong radial evolution on timescales of a few rotation periods (e.g. 5
times 10^8 yrs at a radius of 5 kpc), due to the effectiveness of gravitational
torques in redistributing the cold galactic gas.


title: A Natural Framework for Chaotic Inflation

abstract:
  We show that inflation with a quadratic potential occurs naturally in
theories where an axion-like field mixes with a 4-form. Such an axion is
massive, with the mass which arises from the mixing being protected by the
axion shift symmetry. The 4-form backgrounds break this symmetry spontaneously
and comprise a mini-landscape, where their fluxes can change by emission of
membranes. Inflation can begin when the 4-form dominates the energy density.
Eventually this energy is reduced by membrane emission and the axion can roll
slowly towards its minimum, as in the simplest version of chaotic inflation.


title:
Clean Kinematic Samples in Dwarf Spheroidals: An Algorithm for
  Evaluating Membership and Estimating Distribution Parameters When
  Contamination is Present

abstract:
  (abridged) We develop an algorithm for estimating parameters of a
distribution sampled with contamination, employing a statistical technique
known as ``expectation maximization'' (EM). Given models for both member and
contaminant populations, the EM algorithm iteratively evaluates the membership
probability of each discrete data point, then uses those probabilities to
update parameter estimates for member and contaminant distributions. The EM
approach has wide applicability to the analysis of astronomical data. Here we
tailor an EM algorithm to operate on spectroscopic samples obtained with the
Michigan-MIKE Fiber System (MMFS) as part of our Magellan survey of stellar
radial velocities in nearby dwarf spheroidal (dSph) galaxies. These samples are
presented in a companion paper and contain discrete measurements of
line-of-sight velocity, projected position, and Mg index for ~1000 - 2500 stars
per dSph, including some fraction of contamination by foreground Milky Way
stars. The EM algorithm quantifies both dSph and contaminant distributions,
returning maximum-likelihood estimates of the means and variances, as well as
the probability that each star is a dSph member. Applied to our MMFS data, the
EM algorithm identifies more than 5000 probable dSph members. We test the
performance of the EM algorithm on simulated data sets that represent a range
of sample size, level of contamination, and amount of overlap between dSph and
contaminant velocity distributions. The simulations establish that for samples
ranging from large (N ~3000) to small (N~30), the EM algorithm distinguishes
members from contaminants and returns accurate parameter estimates much more
reliably than conventional methods of contaminant removal (e.g., sigma
clipping).


title: The cosmology dependence of weak lensing cluster counts

abstract:
  We present the main results of a numerical study of weak lensing cluster
counting. We examine the scaling with cosmology of the projected-density-peak
mass function. Our main conclusion is that the projected-peak and the
three-dimensional mass functions scale with cosmology in an astonishingly close
way. This means that, despite being derived from a two-dimensional field, the
weak lensing cluster abundance can be used to constrain cosmology in the same
way as the three-dimensional mass function probed by other types of surveys.


title:
Superstatistical generalisations of Wishart-Laguerre ensembles of random
  matrices

abstract:
  Using Beck and Cohen's superstatistics, we introduce in a systematic way a
family of generalised Wishart-Laguerre ensembles of random matrices with Dyson
index $\beta$ = 1,2, and 4. The entries of the data matrix are Gaussian random
variables whose variances $\eta$ fluctuate from one sample to another according
to a certain probability density $f(\eta)$ and a single deformation parameter
$\gamma$. Three superstatistical classes for $f(\eta)$ are usually considered:
$\chi^2$-, inverse $\chi^2$- and log-normal-distributions. While the first
class, already considered by two of the authors, leads to a power-law decay of
the spectral density, we here introduce and solve exactly a superposition of
Wishart-Laguerre ensembles with inverse $\chi^2$-distribution. The
corresponding macroscopic spectral density is given by a $\gamma$-deformation
of the semi-circle and Mar\v{c}enko-Pastur laws, on a non-compact support with
exponential tails. After discussing in detail the validity of Wigner's surmise
in the Wishart-Laguerre class, we introduce a generalised $\gamma$-dependent
surmise with stretched-exponential tails, which well approximates the
individual level spacing distribution in the bulk. The analytical results are
in excellent agreement with numerical simulations. To illustrate our findings
we compare the $\chi^2$- and inverse $\chi^2$-class to empirical data from
financial covariance matrices.

categories: math-ph cond-mat.stat-mech math.MP nlin.SI


title: Magnetic Fields from Heterotic Cosmic Strings

abstract:
  Large-scale magnetic fields are observed today to be coherent on galactic
scales. While there exists an explanation for their amplification and their
specific configuration in spiral galaxies -- the dynamo mechanism -- a
satisfying explanation for the original seed fields required is still lacking.
Cosmic strings are compelling candidates because of their scaling properties,
which would guarantee the coherence on cosmological scales of any resultant
magnetic fields at the time of galaxy formation. We present a mechanism for the
production of primordial seed magnetic fields from heterotic cosmic strings
arising from M theory. More specifically, we make use of heterotic cosmic
strings stemming from M5--branes wrapped around four of the compact internal
dimensions. These objects are stable on cosmological time scales and carry
charged zero modes. Therefore a scaling solution of such defects will generate
seed magnetic fields which are coherent on galactic scales today.


title: Optical Images of an Exosolar Planet 25 Light Years from Earth

abstract:
  Fomalhaut is a bright star 7.7 parsecs (25 light years) from Earth that
harbors a belt of cold dust with a structure consistent with gravitational
sculpting by an orbiting planet. Here, we present optical observations of an
exoplanet candidate, Fomalhaut b. In the plane of the belt, Fomalhaut b lies
approximately 119 astronomical units (AU) from the star and 18 AU from the
belt, matching predictions. We detect counterclockwise orbital motion using
Hubble Space Telescope observations separated by 1.73 years. Dynamical models
of the interaction between the planet and the belt indicate that the planet's
mass is at most three times that of Jupiter for the belt to avoid gravitational
disruption. The flux detected at 800 nm is also consistent with that of a
planet with mass no greater than a few times that of Jupiter. The brightness at
600 nm and the lack of detection at longer wavelengths suggest that the
detected flux may include starlight reflected off a circumplanetary disk, with
dimension comparable to the orbits of the Galilean satellites. We also observed
variability of unknown origin at 600 nm.


title: Alignment between galaxies and large-scale structure

abstract:
  Based on the Sloan Digital Sky Survey DR6 (SDSS) and Millennium Simulation
(MS) we investigate the alignment between galaxies and large-scale structure.
For this purpose we develop two new statistical tools, namely the alignment
correlation function and the cos(2theta)-statistic. The former is a
two-dimensional extension of the traditional two-point correlation function and
the latter is related to the ellipticity correlation function used for cosmic
shear measurements. Both are based on the cross correlation between a sample of
galaxies with orientations and a reference sample which represents the
large-scale structure. Applied to the SDSS galaxy catalog the alignment
correlation function reveals an overabundance of reference galaxies along the
major axes of red, luminous (L > L*) galaxies out to projected separations of
60 Mpc/h. No alignment signal is detected for blue galaxies. The
cos(2\theta)-statistic yields very similar results. Starting from a MS
semi-analytic galaxy catalog we assign an orientation to each red, luminous and
central galaxy, based on the central region of the host halo. Alternatively, we
use the orientation of the host halo itself. We find a mean projected
misalignment between a halo and its central region of ~25 deg. Agreement with
the SDSS results is good if the central orientations are used. Using the halo
orientations overestimates the observed alignment by more than a factor of 2.
The large volume of the MS allows to generate two-dimensional maps of the
alignment correlation function which show the reference galaxy distribution to
be flattened parallel to the orientations of red luminous galaxies with axis
ratios of ~0.5 and ~0.75 for halo and central orientations,respectively. These
ratios are almost independent of scale out to 60 Mpc/h.


title:
Empirical Constraints on Trojan Companions and Orbital Eccentricities in
  25 Transiting Exoplanetary Systems

abstract:
  We present a search for Trojan companions to 25 transiting exoplanets. We use
the technique of Ford & Gaudi, in which a difference is sought between the
observed transit time and the transit time that is calculated by fitting a
two-body Keplerian orbit to the radial-velocity data. This technique is
sensitive to the imbalance of mass at the L4/L5 points of the planet-star
orbit. No companions were detected above 2\sigma confidence. The median 2\sigma
upper limit is 56 M_\earth, and the most constraining limit is 2.8 M_\earth for
the case of GJ 436. A similar survey using forthcoming data from the Kepler
satellite mission, along with the radial-velocity data that will be needed to
confirm transit candidates, will be sensitive to 10-50 M_\earth Trojan
companions in the habitable zones of their parent stars. As a by-product of
this study, we present empirical constraints on the eccentricities of the
planetary orbits, including those which have previously been assumed to be
circular. The limits on eccentricity are of interest for investigations of
tidal circularization and for bounding possible systematic errors in the
measured planetary radii and the predicted times of secondary eclipses.


title: HST Morphologies of z~2 Dust Obscured Galaxies I: Power-law Sources

abstract:
  We present high spatial resolution optical and near-infrared imaging obtained
using the ACS, WFPC2 and NICMOS cameras aboard the Hubble Space Telescope of 31
24um--bright z~2 Dust Obscured Galaxies (DOGs) identified in the Bootes Field
of the NOAO Deep Wide-Field Survey. Although this subset of DOGs have mid-IR
spectral energy distributions dominated by a power-law component suggestive of
an AGN, all but one of the galaxies are spatially extended and not dominated by
an unresolved component at rest-frame UV or optical wavelengths. The observed
V-H and I-H colors of the extended components are 0.2-3 magnitudes redder than
normal star-forming galaxies. All but 1 have axial ratios >0.3, making it
unlikely that DOGs are composed of an edge-on star-forming disk. We model the
spatially extended component of the surface brightness distributions of the
DOGs with a Sersic profile and find effective radii of 1-6 kpc. This sample of
DOGs is smaller than most sub-millimeter galaxies (SMGs), but larger than
quiescent high-redshift galaxies. Non-parametric measures (Gini and M20) of DOG
morphologies suggest that these galaxies are more dynamically relaxed than
local ULIRGs. We estimate lower limits to the stellar masses of DOGs based on
the rest-frame optical photometry and find that these range from ~10^(9-11)
M_sun. If major mergers are the progenitors of DOGs, then these observations
suggest that DOGs may represent a post-merger evolutionary stage.


title: Remarks on Barbero-Immirzi parameter as a field

abstract:
  We revisit a propagating torsion gravity theory obtained by introducing a
field coupled to the Holst term in the first-order Einstein-Cartan action. The
resulting theory has second order field equations, no adjustable coupling
constants, and one more propagating degree of freedom as compared to general
relativity. When no fermions are present the theory is known to be equivalent
to that of a single massless scalar field canonically coupled to gravity. We
extend this result to the case with fermions and obtain an effective
interaction between the scalar field and the fermionic currents. We also
describe a version of the theory with a potential for the scalar field and
discuss whether it can be interpreted as the inflaton.


title: Macroscopic Objects in Theories with Energy-dependent Speeds of Light

abstract:
  Energy-dependent speeds of light have been considered an observable signature
of quantum gravity effects. The two simplest dispersion relationships produce
either linear or quadratic corrections, in particle energy, to the photon
speed. The macroscopic limits of these theories -- how objects with small
energy per particle, but with large mass, behave -- are not fully understood.
We here briefly discuss some features of the macroscopic limit, that are
necessary for understanding how detectors and emitters interact with the
high-energy photons that probe spacetime.


title:
Period-Luminosity Relations Derived from the OGLE-III Fundamental Mode
  Cepheids

abstract:
  In this Paper, we have derived Cepheid period-luminosity (P-L) relations for
the Large Magellanic Cloud (LMC) fundamental mode Cepheids, based on the data
released from OGLE-III. We have applied an extinction map to correct for the
extinction of these Cepheids. In addition to the VIW band P-L relations, we
also include JHK and four Spitzer IRAC band P-L relations, derived by matching
the OGLE-III Cepheids to the 2MASS and SAGE datasets, respectively. We also
test the non-linearity of the Cepheid P-L relations based on
extinction-corrected data. Our results (again) show that the LMC P-L relations
are non-linear in VIJH bands and linear in KW and the four IRAC bands,
respectively.


title:
Determining Quasar Black Hole Mass Functions from their Broad Emission
  Lines: Application to the Bright Quasar Survey

abstract:
  We describe a Bayesian approach to estimating quasar black hole mass
functions (BHMF) when using the broad emission lines to estimate black hole
mass. We show how using the broad line mass estimates in combination with
statistical techniques developed for luminosity function estimation leads to
statistically biased results. We derive the likelihood function for the BHMF
based on the broad line mass estimates, and derive the posterior distribution
for the BHMF, given the observed data. We develop our statistical approach for
a flexible model where the BHMF is modelled as a mixture of Gaussian functions.
Statistical inference is performed using markov chain monte carlo (MCMC)
methods. Our method has the advantage that it is able to constrain the BHMF
even beyond the survey detection limits at the adopted confidence level,
accounts for measurement errors and the intrinsic uncertainty in broad line
mass estimates, and provides a natural way of estimating the probability
distribution of any quantities derived from the BHMF. We conclude by using our
method to estimate the local active BHMF using the z < 0.5 Bright Quasar Survey
sources. At z = 0.2, the quasar BHMF falls off approximately as a power law
with slope ~ 2 for M_{BH} > 10^8. Our analysis implies that z < 0.5 broad line
quasars have a typical Eddington ratio of ~ 0.4 and a dispersion in Eddington
ratio of < 0.5 dex (abridged).


title: Electromagnetic fields from contact forms

abstract:
  In this short note we prove that every contact form on a 3-manifold M induces
a solution to Maxwell's equations on M.


title: On the (Non)Evolution of HI Disks over Cosmic Time

abstract:
  We present new results on the frequency distribution of projected HI column
densities f(N,X), total comoving covering fraction, and integrated mass
densities rho_HI of high redshift, HI `disks' from a survey of damped Lya
systems (DLAs) in the Sloan Digital Sky Survey, Data Release 5. For the full
sample spanning z=2.2 to 5 [738 DLAs], f(N,X) is well fitted by a double
power-law with a break column density N_d = 10^(21.55 +/- 0.04) and
low/high-end exponents alpha = -2.00 +/- 0.05, -6.4^{+1.1}_{-1.6}. The shape of
f(N,X) is invariant during this redshift interval and also follows the
projected surface density distribution of present-day HI disks as inferred from
21cm observations. We conclude that HI gas has been distributed in a
self-similar fashion for the past 12Gyr. The normalization of f(N,X), in
contrast, decreases by a factor of two during the ~2Gyr interval from z=4 to
2.2 giving corresponding decreases in both the total covering fraction and
rho_HI. At z~2, these quantities match the present-day values suggesting no
evolution during the past ~10Gyr. We argue that the evolution at early times is
driven by `violent' processes that removes gas from nearly half the galaxies at
z~3 establishing the antecedants of current early-type galaxies. The perceived
constancy of rho_HI, meanwhile, implies that HI gas is a necessary but
insufficient pre-condition for star formation and that the global
star-formation rate is driven by the accretion and condensation of fresh gas
from the intergalactic medium.


title: Canny Algorithm, Cosmic Strings and the Cosmic Microwave Background

abstract:
  We describe a new code to search for signatures of cosmic strings in cosmic
microwave anisotropy maps. The code implements the Canny Algorithm, an edge
detection algorithm designed to search for the lines of large gradients in
maps. Such a gradient signature which is coherent in position space is produced
by cosmic strings via the Kaiser-Stebbins effect. We test the power of our new
code to set limits on the tension of the cosmic strings by analyzing simulated
data with and without cosmic strings. We compare maps with a pure Gaussian
scale-invariant power spectrum with maps which have a contribution of a
distribution of cosmic strings obeying a scaling solution. The maps have
angular scale and angular resolution comparable to what current and future
ground-based small-scale cosmic microwave anisotropy experiments will achieve.
We present tests of the codes, indicate the limits on the string tension which
could be set with the current code, and describe various ways to refine the
analysis. Our results indicate that when applied to the data of ongoing cosmic
microwave experiments such as the South Pole Telescope project, the sensitivity
of our method to the presence of cosmic strings will be more than an order of
magnitude better than the limits from existing analyses.


title:
Digital Access to a Sky Century at Harvard. II: Initial Photometry and
  Astrometry

abstract:
  Digital Access to a Sky Century @ Harvard (DASCH) is a project to digitize
the collection of ~500,000 glass photographic plates held at Harvard College
Observatory. The collection spans the time period from 1880 to 1985, during
which time every point on the sky has been observed approximately 500 to 1000
times.
  In this paper we describe the results of the DASCH commissioning run, during
which we developed the data-reduction pipeline and fine-tuned the digitzer's
performance and operation. This initial run consisted of 500 plates taken from
a variety of different plate-series, all containing the open cluster Praeseppe
(M44). We report that accurate photometry at the 0.1mag level is possible on
the majority of plates, and demonstrate century-long light-curves of various
types of variable stars in and around M44.


title: Structure of Neutron Stars in Tensor-Vector-Scalar Theory

abstract:
  Bekenstein's Tensor-Vector-Scalar (TeVeS) theory has had considerable success
in explaining various phenomena without the need for dark matter. However, it
is difficult to observationally discern the differences between TeVeS and
predictions made within the Lambda-cold dark matter concordance model. This
implies that alternative tests are required that independently verify which
theory is correct. For this we turn to the strong-field regime of TeVeS. In
particular, we solve the spherically symmetric equations of hydrostatic
equilibrium for a perfect fluid with a realistic equation of state to build
models of neutron stars in TeVeS. We show that causality within the neutron
star is only maintained for certain cosmological values of the scalar field,
which allows us to put constraints on this value independently of cosmological
observations. We also discuss in detail the internal structure of neutron stars
and how each of the free parameters in the theory effects the overall size and
mass of the neutron stars. In particular, the radii of neutron stars in TeVeS
can significantly differ from those in General Relativity for certain values of
the vector field coupling, which allows us to also place extra constraints on
this parameter. Finally, we discuss future observations of neutron stars using
both the electromagnetic and gravitational wave spectrums that will allow for
tests of the appropriate theory of gravity.


title: Magnetic fields and the location of the PDR

abstract:
  I review recent studies of the emission-line regions in Orion and M17. Both
have similar geometries, a bubble of hot shocked gas surrounding the central
star cluster, with H^+, H^0, and H_2 regions, often referred to as H II
regions, PDRs, and molecular clouds, forming successive shells on the surface
of a molecular cloud. The magnetic fields in the H^0 regions have been measured
with 21 cm Zeeman polarization and are found to be 1 -- 2 dex stronger than the
field in the diffuse ISM. The regions appear to be in rough hydrostatic
equilibrium. The H^+ region is pushed away from the star cluster by starlight
radiation pressure. Since most starlight is in ionizing radiation, most of its
outward push will act on the H^+ region and then on to the H^0 region. The
magnetic pressure in the H^0 region balances the momentum in starlight and
together they set the location of the H^0 region. The picture is that, when the
star cluster formed, it created a bubble of ionized gas which expanded and
compressing surrounding H^0 and H_2 regions. The magnetic field was amplified
until its pressure was able to support the momentum in starlight. This offers a
great simplification in understanding the underlying physics that establishes
parameters for PDR models.


title: Do the nearby BHB stars belong to the Thick Disk or the Halo?

abstract:
  We study the Milky Way region Z<3.0 kpc, where the thick disk and inner halo
overlap, by using the kinematics of local blue horizontal branch (BHB) stars
(within 1 kpc) and new samples of BHB stars and A-type stars from the Century
Survey. We derive Galactic U,V,W velocities for these BHB and A-type star
samples using proper motions from the NOMAD catalog. The mean velocities and
the velocity dispersions of the BHB samples (Z<3 kpc) are characteristic of the
halo, while those of the Century Survey A-type stars are characteristic of the
thick disk. There is no evidence from our samples that the BHB stars rotate
with the thick disk in the region Z<3 kpc. Nearly a third of the nearby local
RR Lyrae stars have disk kinematics and are more metal-rich than [Fe/H]~-1.
Only a few percent of the Century Survey BHB stars have these properties. Only
one nearby BHB star (HD 130201) is likely to be such a disk star but selection
based on high proper motions will have tended to exclude such stars from the
local sample. The scale height derived from a sample of local RR Lyrae stars
agrees with that of the Century Survey BHB stars. The local samples of BHB
stars and metal-weak red giants are too incomplete for a similar comparison.


title: Mutation-selection equilibrium in games with multiple strategies

abstract:
  In evolutionary games the fitness of individuals is not constant but depends
on the relative abundance of the various strategies in the population. Here we
study general games among n strategies in populations of large but finite size.
We explore stochastic evolutionary dynamics under weak selection, but for any
mutation rate. We analyze the frequency dependent Moran process in well-mixed
populations, but almost identical results are found for the Wright-Fisher and
Pairwise Comparison processes. Surprisingly simple conditions specify whether a
strategy is more abundant on average than 1/n, or than another strategy, in the
mutation-selection equilibrium. We find one condition that holds for low
mutation rate and another condition that holds for high mutation rate. A linear
combination of these two conditions holds for any mutation rate. Our results
allow a complete characterization of n*n games in the limit of weak selection.


title: Dressed-particle approach in the nonrelativistic classical limit

abstract:
  For a nonrelativistic classical particle undergoing arbitrary oscillations,
the generalized effective potential Y is derived from nonlinear
eigenfrequencies of the particle-field system. Specifically, the ponderomotive
potential is extended to a nonlinear oscillator, resulting in multiple branches
near the primary resonance. For a pair of natural frequencies in a beat
resonance, Y scales linearly with the internal actions and is analogous to the
dipole potential for a two-level quantum system. Thus cold quantum particles
and highly-excited quasiclassical objects permit uniform manipulation tools,
particularly, one-way walls.


title: Representations of Multiloop Algebras

abstract:
  We describe the finite-dimensional simple modules of all the (twisted and
untwisted) multiloop algebras and classify them up to isomorphism.


title: Contractibility and the Hadwiger Conjecture

abstract:
  Consider the following relaxation of the Hadwiger Conjecture: For each $t$
there exists $N_t$ such that every graph with no $K_t$-minor admits a vertex
partition into $\ceil{\alpha t+\beta}$ parts, such that each component of the
subgraph induced by each part has at most $N_t$ vertices. The Hadwiger
Conjecture corresponds to the case $\alpha=1$, $\beta=-1$ and $N_t=1$.
Kawarabayashi and Mohar [\emph{J. Combin. Theory Ser. B}, 2007] proved this
relaxation with $\alpha={31/2}$ and $\beta=0$ (and $N_t$ a huge function of
$t$). This paper proves this relaxation with $\alpha={7/2}$ and $\beta=-{3/2}$.
The main ingredients in the proof are: (1) a list colouring argument due to
Kawarabayashi and Mohar, (2) a recent result of Norine and Thomas that says
that every sufficiently large $(t+1)$-connected graph contains a $K_t$-minor,
and (3) a new sufficient condition for a graph to have a set of edges whose
contraction increases the connectivity.


title:
Lattice collapse and quenching of magnetism in CaFe2As2 under pressure:
  A single crystal neutron and x-ray diffraction investigation

abstract:
  Single crystal neutron and high-energy x-ray diffraction have identified the
phase lines corresponding to transitions between the ambient-pressure
tetragonal (T), the antiferromagnetic orthorhombic (O) and the non-magnetic
collapsed tetragonal (cT) phases of CaFe2As2. We find no evidence of additional
structures for pressures up to 2.5 GPa (at 300 K). Both the T-cT and O-cT
transitions exhibit significant hysteresis effects and we demonstrate that
coexistence of the O and cT phases can occur if a non-hydrostatic component of
pressure is present. Measurements of the magnetic diffraction peaks show no
change in the magnetic structure or ordered moment as a function of pressure in
the O phase and we find no evidence of magnetic ordering in the cT phase. Band
structure calculations show that the transition results in a strong decrease of
the iron 3d density of states at the Fermi energy, consistent with a loss of
the magnetic moment.


title:
Predictions of Quasar Clustering: Redshift, Luminosity and Selection
  Dependence

abstract:
  We show that current clustering observations of quasars and luminous AGN can
be explained by a merger model augmented by feedback from outflows. Using
numerical simulations large enough to study clustering out to 25 comoving
h^{-1} Mpc, we calculate correlation functions, biases, and correlation lengths
as a function of AGN redshift and optical and X-ray luminosity. At optical
wavelengths, our results match a wide range of current observations and
generate predictions for future data sets. We reproduce the weak luminosity
dependence of clustering over the currently well-measured range, and predict a
much stronger dependence at higher luminosities. The increase in the amplitude
of binary quasar clustering observed in the Sloan Digital Sky Survey (SDSS) is
also reproduced and is predicted to occur at higher redshift, an effect that is
due to the one halo term in the correlation function. On the other hand, our
results do not match the rapid evolution of the correlation length observed in
the SDSS at z\simeq 3, a discrepancy that is at least partially due to
differences in the scales probed by our simulation versus this survey. In fact,
we show that changing the distances sampled from our simulations can produce
changes as large as 40% in the fitted correlation lengths. Finally, in the
X-ray, our simulations produce correlation lengths similar to that observed in
the Chandra Deep Field (CDF) North, but not the significantly larger
correlation length observed in the CDF South.


title:
Metabolomic and flux-balance analysis of age-related decline of hypoxia
  tolerance in Drosophila muscle tissue

abstract:
  The fruit fly D. melanogaster is increasingly used as a model organism for
studying acute hypoxia tolerance and for studying aging, but the interactions
between these two factors are not well known. Here we show that hypoxia
tolerance degrades with age in post-hypoxic recovery of whole-body movement,
heart rate and ATP content. We previously used 1H NMR metabolomics and a
constraint-based model of ATP-generating metabolism to discover the end
products of hypoxic metabolism in flies and generate hypotheses for the
biological mechanisms. We expand the reactions in the model using tissue- and
age-specific microarray data from the literature, and then examine metabolomic
profiles of thoraxes after 4 hours at 0.5% O2 and after 5 minutes of recovery
in 40- versus 3-day-old flies. Model simulations were constrained to fluxes
calculated from these data. Simulations suggest that the decreased ATP
production during reoxygenation seen in aging flies can be attributed to
reduced recovery of mitochondrial respiration pathways and concomitant
over-dependence on the acetate production pathway as an energy source.


title: Land Cover Mapping Using Ensemble Feature Selection Methods

abstract:
  Ensemble classification is an emerging approach to land cover mapping whereby
the final classification output is a result of a consensus of classifiers.
Intuitively, an ensemble system should consist of base classifiers which are
diverse i.e. classifiers whose decision boundaries err differently. In this
paper ensemble feature selection is used to impose diversity in ensembles. The
features of the constituent base classifiers for each ensemble were created
through an exhaustive search algorithm using different separability indices.
For each ensemble, the classification accuracy was derived as well as a
diversity measure purported to give a measure of the inensemble diversity. The
correlation between ensemble classification accuracy and diversity measure was
determined to establish the interplay between the two variables. From the
findings of this paper, diversity measures as currently formulated do not
provide an adequate means upon which to constitute ensembles for land cover
mapping.


title: Effects of anisotropy on optimal dense coding

abstract:
  We study optimal dense coding with thermal entangled states of a two-qubit
anisotropic \emph{XXZ} model and a Heisenberg model with Dzyaloshinski-Moriya
(DM) interactions. The DM interaction is another kind of anisotropic
antisymmetric exchange interaction. The effects of these two kinds of
anisotropies on dense coding are studied in detail for both the
antiferromagnetic and ferromagnetic cases. For the two models, we give the
conditions that the parameters of the models have to satisfy for a valid dense
coding. We also found that even though there is entanglement, it is unavailable
for our optimal dense coding, which is the same as entanglement teleportation.


title: Form Factors and Dyson-Schwinger Equations

abstract:
  A synopsis exemplifying the employment of Dyson-Schwinger equations in the
calculation and explanation of hadron electromagnetic form factors and related
phenomena. In particular the contribution: presents the pion form factor
computed simultaneously at spacelike and timelike momenta; reports aspects of
the evolution of the nucleon and Delta masses with current-quark mass and the
correlation of their mass difference with that between scalar and axial-vector
diquarks; describes an estimate of the s-quark content of a dressed u-quark and
its impact on the nucleon's strangeness magnetic moment; and comments upon the
domain within which a pseudoscalar meson cloud can materially contribute to
hadron form factors.


title:
Peierls Instability Induced Ferromagnetic Insulator at Orbital Order
  Transition

abstract:
  The origin of ferromagnetic insulating state of La$_{7/8}$Sr$_{1/8}$MnO$_3$
is investigated. Based on the tight-binding model, it is shown that this state
can be attributed to the Peierls instability arisen from the interplay of spin
and orbital ordering. The importance of the hole-orbiton-phonon intercoupling
in doped manganites is revealed. This picture explains well the recent
experimental finding of the reentrance of ferromagnetic metal state at low
temperature [Phys. Rev. Lett. 96, 097201 (2006)].


title:
Simulation Study of the Beam Calorimeter in the GLD Configuration for
  the Next Generation Linear Collider

abstract:
  The beam calorimeter, located in the very forward and backward region of the
next generation electron-positron linear accelerator, will be an important
apparatus to search for or identify new particles beyond Standard Model. One of
its key design issues is to estimate the radiation dosage due to beam related
backgrounds. We used the geant-based package, Jupiter, for the proposed GLD
detector in this study. The dosage received per year for the inner most ring
will be around 10 Mrad. An algorithm for electron identification with beam
calorimeter under nominal background condition is developed and is used for the
feasibility study of smuon search. The result is satisfactory.


title: Negative Generators of the Virasoro Constraints for the BKP Hierarchy

abstract:
  We give a straightforward derivation of the string equation and Virasoro
constraints on the $\tau$ function of the BKP hierarchy by means of some
special additional symmetry flows. The explicit forms of the actions of these
additional symmetry flows on the wave function and then the negative Virasoro
generators $L_{-k}$ are given, where $k$ is a positive integer.


title: Spinor Bose-Einstein condensates in double well potentials

abstract:
  We consider the statics and dynamics of F = 1 spinor Bose-Einstein
condensates (BECs) confined in double well potentials. We use a two-mode
Galerkin-type quasi-analytical approximation to describe the stationary states
of the system. This way, we are able to obtain not only earlier results based
on the single mode approximation (SMA) frequently used in studies of spinor
BECs, but also additional modes that involve either two or all three spinor
components of the F = 1 spinor BEC. The results based on this Galerkin-type
decomposition are in good agreement with the analysis of the full system. We
subsequently analyze the stability of these multi-component states, as well as
their dynamics when we find them to be unstable. The instabilities of the
symmetric or anti-symmetric states exhibit symmetry-breaking and recurrent
asymmetric patterns. Our results yield qualitatively similar bifurcation
diagrams both for polar (such as Na23) and ferromagnetic (such as Rb87) spinor
BECs.


title: Crepant resolution conjecture in all genera for type A singularities

abstract:
  We prove an all genera version of the Crepant Resolution Conjecture of Ruan
and Bryan-Graber for type A surface singularities. We are based on a method
that explicitly computes Hurwitz-Hodge integrals described in an earlier paper
and some recent results by Liu-Xu for some intersection numbers on the
Deligne-Mumford moduli spaces. We also generalize our results to some
three-dimensional orbifolds.


title: Applied High Energy QCD

abstract:
  These lectures stress the theoretical elements that underlie a wide range of
phenomenological studies of high-energy QCD, which include both soft and hard
processes. After a brief introduction to the basics of QCD, various aspects of
QCD-based phenomenology are covered: colour transparency, hadronization of
colour charges, Regge phenomenology, parton model, Bjorken scaling and its
violation, DGLAP evolution equation, BFKL formalism, GLR-MQ evolution equation
and saturation. In the last part of the lecture, we employ the light-cone
dipole formalism to describe deep inelastic lepton scattering, Drell-Yan
processes, direct photon production, diffraction, quark and gluon shadowing in
nuclei, the Cronin effect and nuclear broadening.


title: High Temperature Confinement in SU(N) Gauge Theories

abstract:
  SU(N) gauge theories, extended with adjoint fermions having periodic boundary
conditions, are confining at high temperature for sufficiently light fermion
mass m. Lattice simulations indicate that this confining region is smoothly
connected to the confining region of low-temperature pure SU(N) gauge theory.
In the high temperature confining region, the one-loop effective potential for
Polyakov loops has a Z(N)-symmetric confining minimum. String tensions
associated with Polyakov loops are smooth functions of m/T. In the magnetic
sector, the Polyakov loop plays a role similar to a Higgs field, leading to a
breaking of SU(N) to U(1)^{N-1}. This is turn yields an effective theory where
magnetic monopoles give rise to string tensions for spatial Wilson loops. These
string tensions are calculable semiclassically. There are many analytical
predictions for the high-temperature region that can be tested by lattice
simulations, but lattice work will be crucial for exploring the crossover from
this region to the low-temperature confining behavior of pure gauge theories.


title:
A Multivariate Regression Approach to Association Analysis of
  Quantitative Trait Network

abstract:
  Many complex disease syndromes such as asthma consist of a large number of
highly related, rather than independent, clinical phenotypes, raising a new
technical challenge in identifying genetic variations associated simultaneously
with correlated traits. In this study, we propose a new statistical framework
called graph-guided fused lasso (GFlasso) to address this issue in a principled
way. Our approach explicitly represents the dependency structure among the
quantitative traits as a network, and leverages this trait network to encode
structured regularizations in a multivariate regression model over the
genotypes and traits, so that the genetic markers that jointly influence
subgroups of highly correlated traits can be detected with high sensitivity and
specificity. While most of the traditional methods examined each phenotype
independently and combined the results afterwards, our approach analyzes all of
the traits jointly in a single statistical method, and borrow information
across correlated phenotypes to discover the genetic markers that perturbe a
subset of correlated triats jointly rather than a single trait. Using simulated
datasets based on the HapMap consortium data and an asthma dataset, we compare
the performance of our method with the single-marker analysis, and other sparse
regression methods such as the ridge regression and the lasso that do not use
any structural information in the traits. Our results show that there is a
significant advantage in detecting the true causal SNPs when we incorporate the
correlation pattern in traits using our proposed methods.

categories: stat.ML q-bio.GN q-bio.MN q-bio.QM stat.ME


title: PSR J1753-2240: A mildly recycled pulsar in an eccentric binary system

abstract:
  We report the discovery of PSR J1753-2240 in the Parkes Multibeam Pulsar
Survey database. This 95-ms pulsar is in an eccentric binary system with a
13.6-day orbital period. Period derivative measurements imply a characteristic
age in excess of 1 Gyr, suggesting that the pulsar has undergone an episode of
accretion-induced spin-up. The eccentricity and spin period are indicative of
the companion being a second neutron star, so that the system is similar to
that of PSR J1811-1736, although other companion types cannot be ruled out at
this time. The companion mass is constrained by geometry to lie above 0.48
solar masses, although long-term timing observations will give additional
constraints. If the companion is a white dwarf or main sequence star, optical
observations may yield a direct detection of the companion. If the system is
indeed one of the few known double neutron star systems, it would lie
significantly far from the recently proposed spin-period/eccentricity
relationship.


title: The p-adic valuation of k-central binomial coefficients

abstract:
  The coefficients c(n,k) defined by (1-k^2x)^(-1/k) = sum c(n,k) x^n reduce to
the central binomial coefficients for k=2. Motivated by a question of H.
Montgomery and H. Shapiro for the case k=3, we prove that c(n,k) are integers
and study their divisibility properties.


title:
Analogs of the double-Reissner-Nordstrom solution in magnetostatics and
  dilaton gravity: mathematical description and some physical properties

abstract:
  In this paper we consider a magnetic analog of the double-Reissner-Nordstrom
solution and construct the corresponding magnetic potential A_\varphi in the
explicit form. The behavior of the resulting solution under the Harrison
transformation then naturally singles out the asymmetric black diholes -
configurations composed of two non-extreme black holes possessing unequal
masses, and charges equal in magnitude but opposite in sign - as its most
general subclass for which equilibrium of the black-hole constituents can be
achieved with the aid of the external magnetic (or electric) field. We also
generalize the double-Reissner-Nordstrom solution to the dilaton gravity with
arbitrary dilaton coupling, yielding as the result the 4-dimensional
double-Gibbons-Maeda spacetime. The study of some physical properties of the
solutions obtained leads, in particular, to very simple formulas for the areas
of the horizons and surface gravities.


title:
A comparative study of dynamical simulation methods for the dissociation
  of molecular Bose-Einstein condensates

abstract:
  We describe a pairing mean-field theory related to the
Hartree-Fock-Bogoliubov approach, and apply it to the dynamics of dissociation
of a molecular Bose-Einstein condensate (BEC) into correlated bosonic atom
pairs. We also perform the same simulation using two stochastic phase-space
techniques for quantum dynamics -- the positive P-representation method and the
truncated Wigner method. By comparing the results of our calculations we are
able to assess the relative strength of these theoretical techniques in
describing molecular dissociation in one spatial dimension. An important aspect
of our analysis is the inclusion of atom-atom interactions which can be
problematic for the positive-P method. We find that the truncated Wigner method
mostly agrees with the positive-P simulations, but can be simulated for
significantly longer times. The pairing mean-field theory results diverge from
the quantum dynamical methods after relatively short times.


title: Gravitational Radiation from Accreting Millisecond Pulsars

abstract:
  It is widely assumed that the observed reduction of the magnetic field of
millisecond pulsars can be connected to the accretion phase during which the
pulsar is spun up by mass accretion from a companion. A wide variety of
reduction mechanisms have been proposed, including the burial of the field by a
magnetic mountain, formed when the accreted matter is confined to the poles by
the tension of the stellar magnetic field. A magnetic mountain effectively
screens the magnetic dipole moment. On the other hand, observational data
suggests that accreting neutron stars are sources of gravitational waves, and
magnetic mountains are a natural source of a time-dependent quadrupole moment.
We show that the emission is sufficiently strong to be detectable by current
and next generation long-baseline interferometers. Preliminary results from
fully three-dimensional magnetohydrodynamic (MHD) simulations are presented. We
find that the initial axisymmetric state relaxes into a nearly axisymmetric
configuration via toroidal magnetic modes. A substantial quadrupole moment is
still present in the final state, which is stable (in ideal MHD) yet highly
distorted.


title: Exterior-Interior Duality for Discrete Graphs

abstract:
  The Exterior-Interior duality expresses a deep connection between the Laplace
spectrum in bounded and connected domains in $\mathbb{R}^2$, and the scattering
matrices in the exterior of the domains. Here, this link is extended to the
study of the spectrum of the discrete Laplacian on finite graphs. For this
purpose, two methods are devised for associating scattering matrices to the
graphs. The Exterior -Interior duality is derived for both methods.


title:
Higher order nonlinearity in accretion disks: QPOs of black hole and
  neutron star sources and their spin

abstract:
  We propose a unified model to explain Quasi-Periodic-Oscillation (QPO),
particularly of high frequency, observed from black hole and neutron star
systems globally. We consider accreting systems to be damped harmonic
oscillators exhibiting epicyclic oscillations with higher order nonlinear
resonance to explain QPO. The resonance is expected to be driven by the
disturbance from the compact object at its spin frequency. The model explains
various properties parallelly for both types of the compact object. It
describes QPOs successfully for ten different compact sources. Based on it, we
predict the spin frequency of the neutron star Sco X-1 and specific angular
momentum of black holes GRO J1655-40, XTE J1550-564, H1743-322, GRS 1915+105.


title: Transonic properties of the accretion disk around compact objects

abstract:
  An accretion flow is necessarily transonic around a black hole. However,
around a neutron star it may or may not be transonic, depending on the inner
disk boundary conditions influenced by the neutron star. I will discuss various
transonic behavior of the disk fluid in general relativistic (or pseudo general
relativistic) framework. I will address that there are four types of
sonic/critical point possible to form in an accretion disk. It will be shown
that how the fluid properties including location of sonic points vary with
angular momentum of the compact object which controls the overall disk dynamics
and outflows.


title: Nonlocal Dispersion Cancellation using Entangled Photons

abstract:
  A pair of optical pulses traveling through two dispersive media will become
broadened and, as a result, the degree of coincidence between the optical
pulses will be reduced. For a pair of entangled photons, however, nonlocal
dispersion cancellation in which the dispersion experienced by one photon
cancels the dispersion experienced by the other photon is possible. In this
paper, we report an experimental demonstration of nonlocal dispersion
cancellation using entangled photons. The degree of two-photon coincidence is
shown to increase beyond the limit attainable without entanglement. Our results
have important applications in fiber-based quantum communication and quantum
metrology.


title: Three-dimensional topological phase on the diamond lattice

abstract:
  An interacting bosonic model of Kitaev type is proposed on the
three-dimensional diamond lattice. Similarly to the two-dimensional Kitaev
model on the honeycomb lattice which exhibits both Abelian and non-Abelian
phases, the model has two (``weak'' and ``strong'' pairing) phases. In the weak
pairing phase, the auxiliary Majorana hopping problem is in a topological
superconducting phase characterized by a non-zero winding number introduced in
A. P. Schnyder, S. Ryu, A. Furusaki, and A. W. W. Ludwig, arXiv:0803.2786. The
topological character of the weak pairing phase is protected by a discrete
symmetry.


title: Continuum scaling in expansions effective at a large lattice spacing

abstract:
  A new class of truncation schemes of delta expansion on the lattice is
studied. We show that the order of expansion in delta which is introduced as
the dilation parameter can be taken large enough and the result gives rise to
the Borel transformation with respect to the relevant variable in the lattice
models. The explicit simulation of the continuum scaling from the expansion
effective at large spacings is investigated in anharmonic oscillators, d=2
non-linear sigma model at large N and Gross-Neveu model with Wilson fermions.


title: Spectral Effects of Strong Chi-2 Non-Linearity for Quantum Processing

abstract:
  Optical $\chi^{(2)}$ non-linearity can be used for parametric amplification
and producing down-converted entangled photon pairs that have broad
applications. It is known that weak non-linear media exhibit dispersion and
produce a frequency response. It is therefore of interest to know how spectral
effects of a strong $\chi^{(2)}$ crystal affect the performance. Here we model
the spectral effects of the dispersion of a strong $\chi^{(2)}$ crystal and
illustrate how this affects its ability to perform Bell measurements and
influence the performance of a quantum gates that employ such a Bell
measurement. We show that a Dyson series expansion of the unitary operator is
necessary in general, leading to unwanted spectral entanglement. We identify a
limiting situation employing periodic poling, in which a Taylor series
expansion is a good approximation and this entanglement can be removed.


title:
Wannier Orbital Overlap Population (WOOP), Wannier Orbital Position
  Population (WOPP) and the Origin of Anomalous Dynamical Charges

abstract:
  Most d^0 transition metal (TM) oxides exhibit anomalously large Born
dynamical charges associated with off-centering or motion of atoms along the
TM-O chains. To understand their chemical origin, we introduce "Wannier Orbital
Overlap Population" (WOOP) and "Wannier ond Orbital Position Population" (WOPP)
based on the Wannier function based description of electronic structure
obtained within first-principles density functional theory. We apply these
concepts in a precise analysis of anomalous dynamical charges in PbTiO_3,
BaTiO_3 and BaZrO_3 in the cubic perovskite structure. Determining
contributions of different atomic orbitals to the dynamical charge and their
break-up into local polarizability, charge transfer and covalency, we find that
p orbitals of oxygen perpendicular to the -TM-O- chain contribute most
prominently to the anomalous charge, by facilitating a transfer of tiny
electronic charge through one unit cell from one TM atom to the next. Our
results explain why the corner-shared linkage of TMO_6 octahedra, as in the
perovskite structure, is ideal for large dynamical charges and hence for
ferroelectricity.


title: Brownian moving averages have conditional full support

abstract:
  We prove that any Brownian moving average
\[X_t=\int_{-\infty}^t\bigl(f(s-t)-f(s)\bigr) dB_s,\qquad t\ge0,\] satisfies
the conditional full support condition introduced by Guasoni, R\'{a}sonyi and
Schachermayer [Ann. Appl. Probab. 18 (2008) 491--520].


title: The Stellar Populations of Lyman Break Galaxies at z~5

abstract:
  We present the results of Spectral Energy Distribution(SED) fitting analysis
for Lyman Break Galaxies(LBGs) at z~5 in the GOODS-N and its flanking fields
(the GOODS-FF). With the publicly available IRAC images in the GOODS-N and IRAC
data in the GOODS-FF, we constructed the rest-frame UV to optical SEDs for a
large sample (~100) of UV-selected galaxies at z~5. Comparing the observed SEDs
with model SEDs generated with a population synthesis code, we derived a
best-fit set of parameters (stellar mass, age, color excess, and star formation
rate) for each of sample LBGs. The derived stellar masses range from 10^8 to
10^11M_sun with a median value of 4.1x10^9M_sun. The comparison with z=2-3 LBGs
shows that the stellar masses of z~5 LBGs are systematically smaller by a
factor of 3-4 than those of z=2-3 LBGs in a similar rest-frame UV luminosity
range. The star formation ages are relatively younger than those of the z=2-3
LBGs. We also compared the results for our sample with other studies for the
z=5-6 galaxies. Although there seem to be similarities and differences in the
properties, we could not conclude its significance. We also derived a stellar
mass function of our sample by correcting for incompletenesses. Although the
number densities in the massive end are comparable to the theoretical
predictions from semi-analytic models, the number densities in the low-mass
part are smaller than the model predictions. By integrating the stellar mass
function down to 10^8 M_sun, the stellar mass density at z~5 is calculated to
be (0.7-2.4)x10^7M_sun Mpc^-3. The stellar mass density at z~5 is dominated by
massive part of the stellar mass function. Compared with other observational
studies and the model predictions, the mass density of our sample is consistent
with general trend of the increase of the stellar mass density with time.


title: A worm algorithm for the fully-packed loop model

abstract:
  We present a Markov-chain Monte Carlo algorithm of worm type that correctly
simulates the fully-packed loop model on the honeycomb lattice, and we prove
that it is ergodic and has uniform stationary distribution. The fully-packed
loop model on the honeycomb lattice is equivalent to the zero-temperature
triangular-lattice antiferromagnetic Ising model, which is fully frustrated and
notoriously difficult to simulate. We test this worm algorithm numerically and
estimate the dynamic exponent z = 0.515(8). We also measure several static
quantities of interest, including loop-length and face-size moments. It appears
numerically that the face-size moments are governed by the magnetic dimension
for percolation.


title:
Multiband Superconductivity in Heavy Fermion Compound CePt3Si without
  Inversion Symmetry: An NMR Study on a High-Quality Single Crystal

abstract:
  We report on novel superconducting characteristics of the heavy fermion (HF)
superconductor CePt3Si without inversion symmetry through 195Pt-NMR study on a
single crystal with T_c= 0.46 K that is lower than T_c= 0.75 K for
polycrystals. We show that the intrinsic superconducting characteristics
inherent to CePt3Si can be understood in terms of the unconventional
strong-coupling state with a line-node gap below T_c= 0.46 K. The mystery about
the sample dependence of T_c is explained by the fact that more or less
polycrystals and single crystals inevitably contain some disordered domains,
which exhibit a conventional BCS s-wave superconductivity (SC) below 0.8 K. In
contrast, the Neel temperature T_N= 2.2 K is present regardless of the quality
of samples, revealing that the Fermi surface responsible for SC differ from
that for the antiferromagnetic order. These unusual characteristics of CePt3Si
can be also described by a multiband model; in the homogeneous domains, the
coherent HF bands are responsible for the unconventional SC, whereas in the
disordered domains the conduction bands existing commonly in LaPt3Si may be
responsible for the conventional s-wave SC. We remark that some impurity
scatterings in the disordered domains break up the 4f-electrons-derived
coherent bands but not others. In this context, the small peak in 1/T_1 just
below T_c reported in the previous paper (Yogi et al, 2004) is not due to a
two-component order parameter composed of spin-singlet and spin-triplet Cooper
pairing states, but due to the contamination of the disorder domains which are
in the s-wave SC state.


title: Endpoint for the div-curl lemma in Hardy spaces

abstract:
  We give a div-curl type lemma for the wedge product of closed differential
forms on R^n when they have coefficients respectively in a Hardy space and
L^infinity or BMO. In this last case, the wedge product belongs to an
appropriate Hardy-Orlicz space.


title: Remarks on Chern-Simons invariants

abstract:
  The perturbative Chern-Simons theory is studied in a finite-dimensional
version or assuming that the propagator satisfies certain properties (as is the
case, e.g., with the propagator defined by Axelrod and Singer). It turns out
that the effective BV action is a function on cohomology (with shifted degrees)
that solves the quantum master equation and is defined modulo certain canonical
transformations that can be characterized completely. Out of it one obtains
invariants.

categories: math.QA hep-th math-ph math.AT math.GT math.MP


title:
On the laws of first hitting times of points for one-dimensional
  symmetric stable L\'evy processes

abstract:
  Several aspects of the laws of first hitting times of points are investigated
for one-dimensional symmetric stable L\'evy processes. It\^o's excursion theory
plays a key role in this study.