title: The geometry of density states, positive maps and tomograms

abstract:
  The positive and not completely positive maps of density matrices, which are
contractive maps, are discussed as elements of a semigroup. A new kind of
positive map (the purification map), which is nonlinear map, is introduced. The
density matrices are considered as vectors, linear maps among matrices are
represented by superoperators given in the form of higher dimensional matrices.
Probability representation of spin states (spin tomography) is reviewed and
U(N)-tomogram of spin states is presented. Properties of the tomograms as
probability distribution functions are studied. Notion of tomographic purity of
spin states is introduced. Entanglement and separability of density matrices
are expressed in terms of properties of the tomographic joint probability
distributions of random spin projections which depend also on unitary group
parameters. A new positivity criterion for hermitian matrices is formulated. An
entanglement criterion is given in terms of a function depending on unitary
group parameters and semigroup of positive map parameters. The function is
constructed as sum of moduli of U(N)-tomographic symbols of the hermitian
matrix obtained after action on the density matrix of composite system by a
positive but not completely positive map of the subsystem density matrix. Some
two-qubit and two-qutritt states are considered as examples of entangled
states. The connection with the star-product quantisation is discussed. The
structure of the set of density matrices and their relation to unitary group
and Lie algebra of the unitary group are studied. Nonlinear quantum evolution
of state vector obtained by means of applying purification rule of density
matrices evolving via dynamical maps is considered. Some connection of positive
maps and entanglement with random matrices is discussed and used.


title: On Dimer Models and Closed String Theories

abstract:
  We study some aspects of the recently discovered connection between dimer
models and D-brane gauge theories. We argue that dimer models are also
naturally related to closed string theories on non compact orbifolds of $\BC^2$
and $\BC^3$, via their twisted sector R charges, and show that perfect
matchings in dimer models correspond to twisted sector states in the closed
string theory. We also use this formalism to study the combinatorics of some
unstable orbifolds of $\BC^2$.


title:
Relaxation of a dewetting contact line Part 1: A full-scale hydrodynamic
  calculation

abstract:
  The relaxation of a dewetting contact line is investigated theoretically in
the so-called "Landau-Levich" geometry in which a vertical solid plate is
withdrawn from a bath of partially wetting liquid. The study is performed in
the framework of lubrication theory, in which the hydrodynamics is resolved at
all length scales (from molecular to macroscopic). We investigate the
bifurcation diagram for unperturbed contact lines, which turns out to be more
complex than expected from simplified 'quasi-static' theories based upon an
apparent contact angle. Linear stability analysis reveals that below the
critical capillary number of entrainment, Ca_c, the contact line is linearly
stable at all wavenumbers. Away from the critical point the dispersion relation
has an asymptotic behaviour sigma~|q| and compares well to a quasi-static
approach. Approaching Ca_c, however, a different mechanism takes over and the
dispersion evolves from |q| to the more common q^2. These findings imply that
contact lines can not be treated as universal objects governed by some
effective law for the macroscopic contact angle, but viscous effects have to be
treated explicitly.


title: On the spin susceptibility of noncentrosymmetric superconductors

abstract:
  We calculate the spin susceptibility of a superconductor without inversion
symmetry, both in the clean and disordered cases. The susceptibility has a
large residual value at zero temperature, which is further enhanced in the
presence of scalar impurities.


title: Quantum mechanics as a macrorealistic theory

abstract:
  As contrasted with physicists to idolize Bell's theorem and quantum
nonlocality, we argue that quantum mechanics (QM), in reality, respects the
principles of a macroscopic realism (PMRs). The current QM to tell us that "...
the state of a system can be instantaneously changed by a distant measurement
>..." cannot be treated as a physical theory. Its key statements - that the
EPR-Bell experiments to violate Bell's inequality verify nonlocality, and
nonlocal correlations respect special relativity - are false. Both the EPR-Bell
experiments and theorems to support the "non-signalling principle" are based on
the implicit assumption that all quantum postulates and, in particular, Born's
averaging rule are fully applicable to Cat states. However, this is not the
case. Introducing observables (e.g., correlations) for Cat states violates the
correspondence principle. Pure (macro- and micro-)Cat states must be governed
both by the PMRs and superposition principle. Our (macrorealistic) model of a
one-dimensional completed scattering shows how these principles coexist with
each other, in the case of a one-electron micro-Cat state.


title:
Cold Plasma Dispersion Relations in the Vicinity of a Schwarzschild
  Black Hole Horizon

abstract:
  We apply the ADM 3+1 formalism to derive the general relativistic
magnetohydrodynamic equations for cold plasma in spatially flat Schwarzschild
metric. Respective perturbed equations are linearized for non-magnetized and
magnetized plasmas both in non-rotating and rotating backgrounds. These are
then Fourier analyzed and the corresponding dispersion relations are obtained.
These relations are discussed for the existence of waves with positive angular
frequency in the region near the horizon. Our results support the fact that no
information can be extracted from the Schwarzschild black hole. It is concluded
that negative phase velocity propagates in the rotating background whether the
black hole is rotating or non-rotating.


title: Parton Distributions in Impact Parameter Space

abstract:
  Fourier transform of the generalized parton distributions (GPDs) at zero
skewness with respect to the transverse momentum transfer gives the
distribution of partons in the impact parameter space. We investigate the GPDs
as well as the impact parameter dependent parton distributions (ipdpdfs) by
expressing them in terms of overlaps of light front wave functions (LFWFs) and
present a comparative study using three different model LFWFs.


title: The bends on a quantum waveguide and cross-products of Bessel functions

abstract:
  A detailed analysis of the wave-mode structure in a bend and its
incorporation into a stable algorithm for calculation of the scattering matrix
of the bend is presented. The calculations are based on the modal approach. The
stability and precision of the algorithm is numerically and analytically
analysed. The algorithm enables precise numerical calculations of scattering
across the bend. The reflection is a purely quantum phenomenon and is discussed
in more detail over a larger energy interval. The behaviour of the reflection
is explained partially by a one-dimensional scattering model and heuristic
calculations of the scattering matrix for narrow bends. In the same spirit we
explain the numerical results for the Wigner-Smith delay time in the bend.


title:
Ground-state long-range order in quasi-one-dimensional Heisenberg
  quantum antiferromagnets: High-order coupled-cluster calculations

abstract:
  We investigate the ground-state magnetic long-range order of
quasi-one-dimensional quantum Heisenberg antiferromagnets for spin quantum
numbers s=1/2 and s=1. We use the coupled cluster method to calculate the
sublattice magnetization in dependence on the inter-chain coupling. We find
that for the unfrustrated spin-1/2 system an infinitesimal inter-chain coupling
is sufficient to stabilize magnetic long-range order, which is in agreement
with results obtained by some other methods. For s=1 we find that a finite
inter-chain coupling of about 10% of the in-chain coupling is necessary to
stabilize magnetic long-range order. Furthermore, we consider a quasi
one-dimensional spin-1/2 system, where a frustrating next-nearest neighbor
in-chain coupling is included. We find that for stronger frustration also a
finite inter-chain coupling is necessary to have magnetic long-range order in
the ground state, where the strength of the inter-chain coupling necessary to
establish magnetic long-range order is related to the size of the spin gap of
the isolated chain.


title: Relaxation of a dewetting contact line Part 2: Experiments

abstract:
  The dynamics of receding contact lines is investigated experimentally through
controlled perturbations of a meniscus in a dip coating experiment. We first
characterize stationary menisci and their breakdown at the coating transition.
It is then shown that the dynamics of both liquid deposition and
long-wavelength perturbations adiabatically follow these stationary states.
This provides a first experimental access to the entire bifurcation diagram of
dynamical wetting, confirming the hydrodynamic theory developed in Part 1. In
contrast to quasi-static theories based on a dynamic contact angle, we
demonstrate that the transition strongly depends on the large scale flow
geometry. We then establish the dispersion relation for large wavenumbers, for
which we find that sigma is linear in q. The speed dependence of sigma is well
described by hydrodynamic theory, in particular the absence of diverging
time-scales at the critical point. Finally, we highlight some open problems
related to contact angle hysteresis that lead beyond the current description.


title: Graph state generation with noisy mirror-inverting spin chains

abstract:
  We investigate the influence of noise on a graph state generation scheme
which exploits a mirror inverting spin chain. Within this scheme the spin chain
is used repeatedly as an entanglement bus (EB) to create multi-partite
entanglement. The noise model we consider comprises of each spin of this EB
being exposed to independent local noise which degrades the capabilities of the
EB. Here we concentrate on quantifying its performance as a single-qubit
channel and as a mediator of a two-qubit entangling gate, since these are basic
operations necessary for graph state generation using the EB. In particular,
for the single-qubit case we numerically calculate the average channel fidelity
and whether the channel becomes entanglement breaking, i.e., expunges any
entanglement the transferred qubit may have with other external qubits. We find
that neither local decay nor dephasing noise cause entanglement breaking. This
is in contrast to local thermal and depolarizing noise where we determine a
critical length and critical noise coupling, respectively, at which
entanglement breaking occurs. The critical noise coupling for local
depolarizing noise is found to exhibit a power-law dependence on the chain
length. For two qubits we similarly compute the average gate fidelity and
whether the ability for this gate to create entanglement is maintained. The
concatenation of these noisy gates for the construction of a five qubit linear
cluster state and a Greenberger-Horne-Zeilinger state indicates that the level
of noise that can be tolerated for graph state generation is tightly
constrained.


title:
Monte Carlo study of gg->H+jets contribution to Vector Boson Fusion
  Higgs production at the LHC

abstract:
  The contribution of gg->H+jets production process to the vector boson fusion
production of the Higgs boson, VV->H, at LHC was evaluated with the ALPGEN
generator and the PYTHIA shower Monte Carlo including a jet-parton matching
procedure. After the experimental like event selections applied at PYTHIA
particle level, the contribution was found to be 4-5 % for a Higgs boson mass
of 120 GeV.


title:
Reconstruction of the Scalar-Tensor Lagrangian from a LCDM Background
  and Noether Symmetry

abstract:
  We consider scalar-tensor theories and reconstruct their potential U(\Phi)
and coupling F(\Phi) by demanding a background LCDM cosmology. In particular we
impose a background cosmic history H(z) provided by the usual flat LCDM
parameterization through the radiation (w_{eff}=1/3), matter (w_{eff}=0) and
deSitter (w_{eff}=-1) eras. The cosmological dynamical system which is
constrained to obey the LCDM cosmic history presents five critical points in
each era, one of which corresponding to the standard General Relativity (GR).
In the cases that differ from GR, the reconstructed coupling and potential are
of the form F(\Phi)\sim \Phi^2 and U(\Phi)\sim F(\Phi)^m where m is a constant.
This class of scalar tensor theories is also theoretically motivated by a
completely independent approach: imposing maximal Noether symmetry on the
scalar-tensor Lagrangian. This approach provides independently: i) the form of
the coupling and the potential as F(\Phi)\sim \Phi^2 and U(\Phi)\sim F(\Phi)^m,
ii) a conserved charge related to the potential and the coupling and iii)
allows the derivation of exact solutions by first integrals of motion.

categories: astro-ph gr-qc hep-ph hep-th math-ph math.MP


title:
Schr\"odinger-Wheeler-DeWitt equation in chaplygin gas FRW cosmological
  model

abstract:
  We present a chaplygin gas Friedmann-Robertson-Walker quantum cosmological
model. In this work the Schutz's variational formalism is applied with
positive, negative, and zero constant spatial curvature. In this approach the
notion of time can be recovered. These give rise to
Schr\"odinger-Wheeler-DeWitt equation for the scale factor. We use the
eigenfunctions in order to construct wave packets for each case. We study the
time dependent behavior of the expectation value of the scale factor, using the
many-worlds interpretations of quantum mechanics.


title:
Convergence of excursion point processes and its applications to
  functional limit theorems of Markov processes on a half-line

abstract:
  Invariance principles are obtained for a Markov process on a half-line with
continuous paths on the interior. The domains of attraction of the two
different types of self-similar processes are investigated. Our approach is to
establish convergence of excursion point processes, which is based on It\^{o}'s
excursion theory and a recent result on convergence of excursion measures by
Fitzsimmons and the present author.


title: Supersymmetric Adjoint SU(5)

abstract:
  Recently we have proposed a renormalizable grand unified theory, based on the
SU(5) gauge symmetry, where the neutrino masses are generated through the type
I and type III seesaw mechanisms. In this letter we study the supersymmetric
version of this theory. As in the non-susy version it is possible to generate
all fermion masses with the minimal number of Higgses, the theory predicts one
massless neutrino and the leptogenesis mechanism can be realized. All
contributions to the decay of the proton and the properties of neutralinos are
discussed. This theory can be considered as the simplest renormalizable
supersymmetric grand unified theory based on the SU(5) gauge symmetry since it
has the minimal number of superfields and free parameters.


title: Orthogonal arrays from Hermitian varieties

abstract:
  An orthogonal array OA(q^{2n-1},q^{2n-2}, q,2) is constructed from the action
of a subset of PGL(n+1,q^2) on some non--degenerate Hermitian varieties in
PG(n,q^2). It is also shown that the rows of this orthogonal array correspond
to some blocks of an affine design, which for q> 2 is a non--classical model of
the affine space AG(2n-1,q).


title:
The Gribov-Zwanziger action in the presence of the gauge invariant,
  nonlocal mass operator $Tr \int d^4x F_{\mu\nu} (D^2)^{-1} F_{\mu\nu}$ in the
  Landau gauge

abstract:
  We prove that the nonlocal gauge invariant mass dimension two operator
$F_{\mu\nu} (D^2)^{-1} F_{\mu\nu}$ can be consistently added to the
Gribov-Zwanziger action, which implements the restriction of the path
integral's domain of integration to the first Gribov region when the Landau
gauge is considered. We identify a local polynomial action and prove the
renormalizability to all orders of perturbation theory by employing the
algebraic renormalization formalism. Furthermore, we also pay attention to the
breaking of the BRST invariance, and to the consequences that this has for the
Slavnov-Taylor identity.


title:
A solution of a problem of Sophus Lie: Normal forms of 2-dim metrics
  admitting two projective vector fields

abstract:
  We give a complete list of normal forms for the 2-dimensional metrics that
admit a transitive Lie pseudogroup of geodesic-preserving transformations and
we show that these normal forms are mutually non-isometric. This solves a
problem posed by Sophus Lie.


title: MI image registration using prior knowledge

abstract:
  Subtraction of aligned images is a means to assess changes in a wide variety
of clinical applications. In this paper we explore the information theoretical
origin of Mutual Information (MI), which is based on Shannon's entropy.However,
the interpretation of standard MI registration as a communication channel
suggests that MI is too restrictive a criterion. In this paper the concept of
Mutual Information (MI) is extended to (Normalized) Focussed Mutual Information
(FMI) to incorporate prior knowledge to overcome some shortcomings of MI. We
use this to develop new methodologies to successfully address specific
registration problems, the follow-up of dental restorations, cephalometry, and
the monitoring of implants.


title:
Parallel tracks in infrared versus X-ray emission in black hole X-ray
  transient outbursts: a hysteresis effect?

abstract:
  We report the discovery of a new hysteresis effect in black hole X-ray binary
state transitions, that of the near-infrared (NIR) flux (which most likely
originates in the jets) versus X-ray flux. We find, looking at existing data
sets, that the infrared emission of black hole X-ray transients appears to be
weaker in the low/hard state rise of an outburst than the low/hard state
decline of an outburst at a given X-ray luminosity. We discuss how this effect
may be caused by a shift in the radiative efficiency of the inflowing or
outflowing matter, or variations in the disc viscosity or the spectrum/power of
the jet. In addition we show that there is a correlation (in slope but not in
normalisation) between infrared and X-ray luminosities on the rise and decline,
for all three low-mass black hole X-ray binaries with well-sampled infrared and
X-ray coverage: L_NIR propto L_x^(0.5-0.7). In the high/soft state this slope
is much shallower; L_NIR propto Lx^(0.1-0.2), and we find that the NIR emission
in this state is most likely dominated by the viscously heated (as opposed to
X-ray heated) accretion disc in all three sources.


title:
Polarized emission lines from A- and B-type excitonic complexes in
  single InGaN/GaN quantum dots

abstract:
  Cathodoluminescence measurements on single InGaN/GaN quantum dots (QDs) are
reported. Complex spectra with up to five emission lines per QD are observed.
The lines are polarized along the orthogonal crystal directions [1 1 -2 0] and
[-1 1 0 0]. Realistic eight-band k.p electronic structure calculations show
that the polarization of the lines can be explained by excitonic recombinations
involving hole states which are either formed by the A or the B valence band.


title: An XMM-Newton study of Hyper-Luminous Infrared Galaxies

abstract:
  Hyper-Luminous Infrared Galaxies (HLIRGs) are the most luminous persistent
objects in the Universe. They exhibit extremely high star formation rates, and
most of them seem to harbour an AGN. They are unique laboratories to
investigate utmost star formation, and its connection to super-massive black
hole growth. X-ray studies of HLIRGs have the potential to unravel the AGN
contribution to the bolometric output from these bright objects.
  We have selected a sample of 14 HLIRGs observed by XMM-Newton (type 1, type 2
AGN and starburst), 5 of which are candidates to be Compton-thick objects. This
is the first time that a systematic study of this type of objects is carried
out in the X-ray spectral band. Their X-ray spectral properties have been
correlated with their IR luminosities, estimated by IRAS, ISO and sub-mm data.
  The X-ray spectra of HLIRGs present heterogeneous properties. All our X-ray
detected HLIRGs (10) have AGN-dominated X-ray spectra. The hard X-ray
luminosity of 8 of them is consistent with a pure AGN contribution, while in
the remaining 2 sources both an AGN and a starburst seem to contribute to the
overall emission. We found soft excess emission in 5 sources. In one of them it
is consistent with a pure starburst origin, while in the other 4 sources it is
consistent with an AGN origin. The observed X-ray emission is systematically
below the one expected for a standard local QSO of the same IR luminosity,
suggesting the possible presence of absorption in type 2 objects and/or a
departure from a standard spectral energy distribution of QSO. The
X-ray-to-IR-luminosity ratio is constant with redshift, indicating similar
evolutions for the AGN and starburst component, and that their respective power
sources could be physically related.


title: DNA Hash Pooling and its Applications

abstract:
  In this paper we describe a new technique for the comparison of populations
of DNA strands. Comparison is vital to the study of ecological systems, at both
the micro and macro scales. Existing methods make use of DNA sequencing and
cloning, which can prove costly and time consuming, even with current
sequencing techniques. Our overall objective is to address questions such as:
(i) (Genome detection) Is a known genome sequence present, at least in part, in
an environmental sample? (ii) (Sequence query) Is a specific fragment sequence
present in a sample? (iii) (Similarity discovery) How similar in terms of
sequence content are two unsequenced samples? We propose a method involving
multiple filtering criteria that result in "pools" of DNA of high or very high
purity. Because our method is similar in spirit to hashing in computer science,
we call it DNA hash pooling. To illustrate this method, we describe protocols
using pairs of restriction enzymes. The in silico empirical results we present
reflect a sensitivity to experimental error. Our method will normally be
performed as a filtering step prior to sequencing in order to reduce the amount
of sequencing required (generally by a factor of 10 or more). Even as
sequencing becomes cheaper, an order of magnitude remains important.


title:
Pseudoprocesses governed by higher-order fractional differential
  equations

abstract:
  We study here a heat-type differential equation of order n greater than two,
in the case where the time-derivative is supposed to be fractional. The
corresponding solution can be described as the transition function of a
pseudoprocess (coinciding with the one governed by the standard,
non-fractional, equation) with a time argument T which is itself random. The
distribution of T is presented together with some features of the solution
(such as analytic expressions for its moments).


title:
Integer symmetric matrices having all their eigenvalues in the interval
  [-2,2]

abstract:
  We completely describe all integer symmetric matrices that have all their
eigenvalues in the interval [-2,2]. Along the way we classify all signed
graphs, and then all charged signed graphs, having all their eigenvalues in
this same interval. We then classify subsets of the above for which the integer
symmetric matrices, signed graphs and charged signed graphs have all their
eigenvalues in the open interval (-2,2).


title:
Weil-Petersson volume of moduli spaces, Mirzakhani's recursion and
  matrix models

abstract:
  We show that Mirzakhani's recursions for the volumes of moduli space of
Riemann surfaces are a special case of random matrix loop equations, and
therefore we confirm again that Kontsevitch's integral is a generating function
for those volumes. As an application, we propose a formula for the
Weil-Petersson volume Vol(M_{g,0}).


title: Spin Description in the Star Product and the Path Integral Formalism

abstract:
  The spin can be described in the star product formalism by extending the
bosonic Moyal product in the fermionic sector. The fermionic star product is
then the Clifford product of geometric algebra and it is possible to formulate
the fermionic star product formalism in analogy to the bosonic star product
formalism. For the fermionic star product description of spin, one can then
establish the relation to other approaches that describe spin with fermionic
variables, i.e. the operator formalism and the path integral formalism. It is
shown that the fermionic star product formalism and the fermionic path integral
formalism are related in analogy to their bosonic counterparts.


title:
Spinal partitions and invariance under re-rooting of continuum random
  trees

abstract:
  We develop some theory of spinal decompositions of discrete and continuous
fragmentation trees. Specifically, we consider a coarse and a fine spinal
integer partition derived from spinal tree decompositions. We prove that for a
two-parameter Poisson--Dirichlet family of continuous fragmentation trees,
including the stable trees of Duquesne and Le Gall, the fine partition is
obtained from the coarse one by shattering each of its parts independently,
according to the same law. As a second application of spinal decompositions, we
prove that among the continuous fragmentation trees, stable trees are the only
ones whose distribution is invariant under uniform re-rooting.


title: Vlasov moments, integrable systems and singular solutions

abstract:
  The Vlasov equation for the collisionless evolution of the single-particle
probability distribution function (PDF) is a well-known Lie-Poisson Hamiltonian
system. Remarkably, the operation of taking the moments of the Vlasov PDF
preserves the Lie-Poisson structure. The individual particle motions correspond
to singular solutions of the Vlasov equation. The paper focuses on singular
solutions of the problem of geodesic motion of the Vlasov moments. These
singular solutions recover geodesic motion of the individual particles.

categories: nlin.SI math-ph math.MP physics.acc-ph physics.plasm-ph


title: Measure of full dimension for some nonconformal repellers

abstract:
  We prove the existence of an ergodic measure with full Hausdorff dimension
for a class of nonlinear nonconformal skew-product transformations. In order to
do so we establish a variational principle for the topological pressure of
certain noncompact sets.


title:
Four Drafts of The Representation Theory of the Group of Infinite
  Matrices over Finite Fields

abstract:
  Preface (A.Vershik) - about these texts (3.);
  I.Interpolation between inductive and projective limits of finite groups with
applicatons to linear groups over finite fields;
  II.The characters of the groups of almost triangle matrices over finite
filed;
  III.A Law of Large Numbers for the characters of GL_n(k) over finite field k;
  IV.An outline of construction of factor representations of the group
GLB(F_q).


title: Particle transfer in braneworld collisions

abstract:
  We study the behaviour of fermions localized on moving kinks as these collide
with either antikinks or spacetime boundaries. We numerically solve for the
evolution of the scalar kinks and the bound (i.e. localized) fermion modes, and
calculate the number of fermions transfered to the antikink and boundary in
terms of Bogoliubov coefficients. Interpreting the boundary as the brane on
which we live, this models the ability of fermions on branes incoming from the
bulk to ``stick'' on the world brane, even when the incoming branes bounce back
into the bulk.


title: Star Products for Relativistic Quantum Mechanics

abstract:
  The star product formalism has proved to be an alternative formulation for
nonrelativistic quantum mechanics. We want introduce here a covariant star
product in order to extend the star product formalism to relativistic quantum
mechanics in the proper time formulation.


title: d=4+1 gravitating nonabelian solutions with bi-azimuthal symmetry

abstract:
  We construct static, asymptotically flat solutions of SU(2)
Einstein-Yang-Mills theory in 4+1 dimensions, subject to bi-azimuthal symmetry.
Both particle-like and black hole solutions are considered for two different
sets of boundary conditions in the Yang--Mills sector, corresponding to
multisolitons and soliton-antisoliton pairs. For gravitating multi-soliton
solutions, we find that their mass per unit charge is lower than the mass of
the corresponding unit charge, spherically symmetric soliton.


title: Structure and Classification of Superconformal Nets

abstract:
  We study the general structure of Fermi conformal nets of von Neumann
algebras on the circle, consider a class of topological representations, the
general representations, that we characterize as Neveu-Schwarz or Ramond
representations, in particular a Jones index can be associated with each of
them. We then consider a supersymmetric general representation associated with
a Fermi modular net and give a formula involving the Fredholm index of the
supercharge operator and the Jones index. We then consider the net associated
with the super-Virasoro algebra and discuss its structure. If the central
charge c belongs to the discrete series, this net is modular by the work of F.
Xu and we get an example where our setting is verified by considering the
Ramond irreducible representation with lowest weight c/24. We classify all the
irreducible Fermi extensions of any super-Virasoro net in the discrete series,
thus providing a classification of all superconformal nets with central charge
less than 3/2.


title: A Logic of Reachable Patterns in Linked Data-Structures

abstract:
  We define a new decidable logic for expressing and checking invariants of
programs that manipulate dynamically-allocated objects via pointers and
destructive pointer updates. The main feature of this logic is the ability to
limit the neighborhood of a node that is reachable via a regular expression
from a designated node. The logic is closed under boolean operations
(entailment, negation) and has a finite model property. The key technical
result is the proof of decidability. We show how to express precondition,
postconditions, and loop invariants for some interesting programs. It is also
possible to express properties such as disjointness of data-structures, and
low-level heap mutations. Moreover, our logic can express properties of
arbitrary data-structures and of an arbitrary number of pointer fields. The
latter provides a way to naturally specify postconditions that relate the
fields on entry to a procedure to the fields on exit. Therefore, it is possible
to use the logic to automatically prove partial correctness of programs
performing low-level heap mutations.


title:
Evidence for a jet contribution to the optical/infrared light of neutron
  star X-ray binaries

abstract:
  Optical/near-infrared (optical/NIR; OIR) light from low-mass neutron star
X-ray binaries (NSXBs) in outburst is traditionally thought to be thermal
emission from the accretion disc. Here we present a comprehensive collection of
quasi-simultaneous OIR and X-ray data from 19 low-magnetic field NSXBs,
including new observations of three sources: 4U 0614+09, LMC X-2 and GX 349+2.
The average radio-OIR spectrum for NSXBs is alpha ~ +0.2 (where L_nu propto
nu^alpha) at least at high luminosities when the radio jet is detected. This is
comparable to, but slightly more inverted than the alpha ~ 0.0 found for black
hole X-ray binaries. The OIR spectra and relations between OIR and X-ray fluxes
are compared to those expected if the OIR emission is dominated by thermal
emission from an X-ray or viscously heated disc, or synchrotron emission from
the inner regions of the jets. We find that thermal emission due to X-ray
reprocessing can explain all the data except at high luminosities for some
NSXBs, namely the atolls and millisecond X-ray pulsars (MSXPs). Optically thin
synchrotron emission from the jets (with an observed OIR spectral index of
alpha_thin < 0) dominate the NIR light above L_x ~ 10^36 erg/s and the optical
above L_x ~ 10^37 erg/s in these systems. For NSXB Z-sources, the OIR
observations can be explained by X-ray reprocessing alone, although synchrotron
emission may make a low level contribution to the NIR, and could dominate the
OIR in one or two cases.


title: Swimming with a friend at low Reynolds number

abstract:
  We investigate the hydrodynamic interactions between microorganisms swimming
at low Reynolds number. By considering simple model swimmers, and combining
analytic and numerical approaches, we investigate the time-averaged flow field
around a swimmer. At short distances the swimmer behaves like a pump. At large
distances the velocity field depends on whether the swimming stroke is
invariant under a combined time-reversal and parity transformation. We then
consider two swimmers and find that the interaction between them consists of
two parts; a dead term, independent of the motion of the second swimmer, which
takes the expected dipolar form and a live term resulting from the simultaneous
swimming action of both swimmers which does not. We argue that, in general, the
latter dominates. The swimmer--swimmer interaction is a complicated function of
their relative displacement, orientation and phase, leading to motion that can
be attractive, repulsive or oscillatory.

categories: cond-mat.soft cond-mat.other physics.bio-ph q-bio.OT


title:
Effects of correlations on the total neutron-Nucleus cross section at
  high energies

abstract:
  The total neutron-Nucleus cross section has been calculated within an
approach which takes into account nucleon-nucleon correlations, Glauber
multiple scattering and inelastic shadowing corrections. Nuclear targets
ranging from 4He to 208Pb and neutron incident momentum ranging from 3 to 300
GeV/c, have been considered. Correlations have been introduced by two different
approaches leading to the same results. The commonly used approximation,
consisting in treating nuclear effects only by a product of one-body densities,
is carefully analyzed and it is shown that the effects of realistic
correlations resulting from modern nucleon-nucleon interactions and realistic
correlations resulting from realistic nucleon-nucleon interactions and
microscopic ground state calculation of nuclear properties cannot be
disregarded.


title: Bounding slopes of $p$-adic modular forms

abstract:
  Let $p$ be prime, $N$ be a positive integer prime to $p$, and $k$ be an
integer. Let $P_k(t)$ be the characteristic series for Atkin's $U$ operator as
an endomorphism of $p$-adic overconvergent modular forms of tame level $N$ and
weight $k$. Motivated by conjectures of Gouvea and Mazur, we strengthen Wan's
congruence between coefficients of $P_k$ and $P_{k'}$ for $k'$ close
$p$-adically to $k$. For $p-1 | 12$, $N = 1$, $k = 0$, we compute a matrix for
$U$ whose entries are coefficients in the power series of a rational function
of two variables. We apply this computation to show for $p = 3$ a parabola
below the Newton polygon $N_0$ of $P_0$, which coincides with $N_0$ infinitely
often. As a consequence, we find a polygonal curve above $N_0$. This tightest
bound on $N_0$ yields the strongest congruences between coefficients of $P_0$
and $P_k$ for $k$ of large 3-adic valuation.


title: Electromagnetically induced transparency for x rays

abstract:
  Electromagnetically induced transparency (EIT) is predicted for x rays in
laser-dressed neon gas. The x-ray photoabsorption cross section and
polarizability near the Ne K edge are calculated using an ab initio theory
suitable for optical strong-field problems. The laser wavelength is tuned close
to the transition between 1s^-1 3s and 1s^-1 3p (approximately 800nm). The
minimum laser intensity required to observe EIT is of the order of 10^12
W/cm^2. The ab initio results are discussed in terms of an exactly solvable
three-level model. This work opens new opportunities for research with
ultrafast x-ray sources.


title: On How Developers Test Open Source Software Systems

abstract:
  Engineering software systems is a multidisciplinary activity, whereby a
number of artifacts must be created - and maintained - synchronously. In this
paper we investigate whether production code and the accompanying tests
co-evolve by exploring a project's versioning system, code coverage reports and
size-metrics. Three open source case studies teach us that testing activities
usually start later on during the lifetime and are more "phased", although we
did not observe increasing testing activity before releases. Furthermore, we
note large differences in the levels of test coverage given the proportion of
test code.


title:
Final State Interaction Effects in Semi-inclusive Deep Inelastic
  processes A(e,e'p)X off the deuteron and complex nuclei

abstract:
  The effects of the final state interaction (FSI) in semi inclusive deep
inelastic electron scattering processes $A(e,e'p)X$ off nuclei are investigated
in details. Proton production is described within the spectator and the target
fragmentation mechanisms whose relevance to the experimental study of the deep
inelastic structure functions of bound nucleons and the non perturbative
hadronization process is analyzed. Particular attention is paid to the deuteron
target within kinematical conditions corresponding to the available and
forthcoming experimental data at Jlab.
  We argue that there are kinematical regions where FSI effects are minimized,
allowing for a reliable investigation of the DIS structure functions, and
regions where the interaction of the quark-gluon debris with nucleons is
maximized, which makes it possible to study hadronization mechanisms. Nuclear
structure has been described by means of realistic wave functions and spectral
functions and the final state interaction has been treated within an eikonal
approximation approach which takes into account the rescattering of the
quark-gluon debris with the residual nucleus and, in the case of complex
nuclei, within an optical potential approach to account for the FSI of the
struck proton.


title:
Electronic Interface Reconstruction at Polar-Nonpolar Mott Insulator
  Heterojunctions

abstract:
  We report on a theoretical study of the electronic interface reconstruction
(EIR) induced by polarity discontinuity at a heterojunction between a polar and
a nonpolar Mott insulators, and of the two-dimensional strongly-correlated
electron systems (2DSCESs) which accompany the reconstruction. We derive an
expression for the minimum number of polar layers required to drive the EIR,
and discuss key parameters of the heterojunction system which control 2DSCES
properties. The role of strong correlations in enhancing confinement at the
interface is emphasized.


title:
A New Class of Inhomogeneous String Cosmological Models in General
  Relativity

abstract:
  A new class of solutions of Einstein field equations has been investigated
for inhomogeneous cylindrically symmetric space-time with string source. To get
the deterministic solution, it has been assumed that the expansion ($\theta$)
in the model is proportional to the eigen value $\sigma^{1}_{1}$ of the shear
tensor $\sigma^{i}_{j}$. Certain physical and geometric properties of the
models are also discussed.


title:
Scalar-field perturbations from a particle orbiting a black hole using
  numerical evolution in 2+1 dimensions

abstract:
  We present a new technique for time-domain numerical evolution of the scalar
field generated by a pointlike scalar charge orbiting a black hole. Time-domain
evolution offers an efficient way for calculating black hole perturbations,
especially as input for computations of the local self force acting on orbiting
particles. In Kerr geometry, the field equations are not fully separable in the
time domain, and one has to tackle them in 2+1 dimensions (two spatial
dimensions and time; the azimuthal dependence is still separable). A technical
difficulty arises when the source of the field is a pointlike particle, as the
2+1-dimensional perturbation is then singular: Each of the azimuthal modes
diverges logarithmically at the particle. To deal with this problem we split
the numerical domain into two regions: Inside a thin worldtube surrounding the
particle's worldline we solve for a regularized variable, obtained from the
full field by subtracting out a suitable ``puncture'' function, given
analytically. Outside this worldtube we solve for the full, original field. The
value of the evolution variable is adjusted across the boundary of the
worldtube. In this work we demonstrate the applicability of this method in the
example of circular orbits around a Schwarzschild black hole (refraining from
exploiting the spherical symmetry of the background, and working in 2+1
dimensions).


title:
MHD simulations of the magnetorotational instability in a shearing box
  with zero net flux. I. The issue of convergence

abstract:
  We study the properties of MHD turbulence driven by the magnetorotational
instability (MRI) in accretion disks. We adopt the local shearing box model and
focus on the special case for which the initial magnetic flux threading the
disk vanishes. We employ the finite difference code ZEUS to evolve the ideal
MHD equations. Performing a set of numerical simulations in a fixed
computational domain with increasing resolution, we demonstrate that turbulent
activity decreases as resolution increases. We quantify the turbulent activity
by measuring the rate of angular momentum transport through evaluating the
standard alpha parameter. We find alpha=0.004 when (N_x,N_y,N_z)=(64,100,64),
alpha=0.002 when (N_x,N_y,N_z)=(128,200,128) and alpha=0.001 when
(N_x,N_y,N_z)=(256,400,256). This steady decline is an indication that
numerical dissipation, occurring at the grid scale is an important determinant
of the saturated form of the MHD turbulence. Analysing the results in Fourier
space, we demonstrate that this is due to the MRI forcing significant flow
energy all the way down to the grid dissipation scale. We also use our results
to study the properties of the numerical dissipation in ZEUS. Its amplitude is
characterised by the magnitude of an effective magnetic Reynolds number Re_M
which increases from 10^4 to 10^5 as the number of grid points is increased
from 64 to 256 per scale height. The simulations we have carried out do not
produce results that are independent of the numerical dissipation scale, even
at the highest resolution studied. Thus it is important to use physical
dissipation, both viscous and resistive, and to quantify contributions from
numerical effects, when performing numerical simulations of MHD turbulence with
zero net flux in accretion disks at the resolutions normally considered.


title:
MHD simulations of the magnetorotational instability in a shearing box
  with zero net flux. II. The effect of transport coefficients

abstract:
  We study the influence of the choice of transport coefficients (viscosity and
resistivity) on MHD turbulence driven by the magnetorotational instability
(MRI) in accretion disks. We follow the methodology described in paper I: we
adopt an unstratified shearing box model and focus on the case where the net
vertical magnetic flux threading the box vanishes. For the most part we use the
finite difference code ZEUS, including explicit transport coefficients in the
calculations. However, we also compare our results with those obtained using
other algorithms (NIRVANA, the PENCIL code and a spectral code) to demonstrate
both the convergence of our results and their independence of the numerical
scheme. We find that small scale dissipation affects the saturated state of MHD
turbulence. In agreement with recent similar numerical simulations done in the
presence of a net vertical magnetic flux, we find that turbulent activity
(measured by the rate of angular momentum transport) is an increasing function
of the magnetic Prandtl number Pm for all values of the Reynolds number Re that
we investigated. We also found that turbulence disappears when the Prandtl
number falls below a critical value Pm_c that is apparently a decreasing
function of Re. For the limited region of parameter space that can be probed
with current computational resources, we always obtained Pm_c>1. We conclude
that the magnitudes of the transport coefficients are important in determining
the properties of MHD turbulence in numerical simulations in the shearing box
with zero net flux, at least for Reynolds numbers and magnetic Prandtl numbers
that are such that transport is not dominated by numerical effects and thus can
be probed using current computational resources.


title:
String Cosmological Model in Cylindrically Symmetric Inhomogeneous
  Universe with Electromagnetic Field II

abstract:
  Cylindrically symmetric inhomogeneous string cosmological model of the
universe in presence of electromagnetic field is investigated. We have assumed
that F_{12} is the only non-vanishing component of electromagnetic field tensor
F_{ij}. The Maxwell's equations show that F_{12} is the function of $x$ alone
whereas the magnetic permeability is the function of x and t both. To get the
deterministic solution, it has been assumed that the expansion ($\theta$) in
the model is proportional to the eigen value $\sigma^{1}_{1}$ of the shear
tensor $\sigma^{i}_{j}$. Some physical and geometric prperties of the model are
also discussed.


title:
Towards a systematic design of isotropic bulk magnetic metamaterials
  using the cubic point groups of symmetry

abstract:
  In this paper a systematic approach to the design of bulk isotropic magnetic
metamaterials is presented. The role of the symmetries of both the constitutive
element and the lattice are analyzed. For this purpose it is assumed that the
metamaterial is composed by cubic SRR resonators, arranged in a cubic lattice.
The minimum symmetries needed to ensure an isotropic behavior are analyzed, and
some particular configurations are proposed. Besides, an equivalent circuit
model is proposed for the considered cubic SRR resonators. Experiments are
carried out in order to validate the proposed theory. We hope that this
analysis will pave the way to the design of bulk metamaterials with strong
isotropic magnetic response, including negative permeability and left-handed
metamaterials.


title:
Universal Bound on Dynamical Relaxation Time from Condition for Relaxing
  Quantity to be Classical

abstract:
  It is shown that the Hod's universal bound on the relaxation time of a
perturbed system \cite{hod} can be derived from a well-known condition for a
relaxing quantity to be classical in the fluctuation theory.


title:
Mode stability in delta Scuti stars: linear analysis versus observations
  in open clusters

abstract:
  A comparison between linear stability analysis and observations of pulsation
modes in five delta Scuti stars, belonging to the same cluster, is presented.
The study is based on the work by Michel et al. (1999), in which such a
comparison was performed for a representative set of model solutions obtained
independently for each individual star considered. In this paper we revisit the
work by Michel et al. (1999) following, however, a new approach which consists
in the search for a single, complete, and coherent solution for all the
selected stars, in order to constrain and test the assumed physics describing
these objects. To do so, refined descriptions for the effects of rotation on
the determination of the global stellar parameters and on the adiabatic
oscillation frequency computations are used. In addition, a crude attempt is
made to study the role of rotation on the prediction of mode instabilities.The
present results are found to be comparable with those reported by Michel et al.
(1999). Within the temperature range log T_eff = 3.87-3.88 agreement between
observations and model computations of unstable modes is restricted to values
for the mixing-length parameter alpha_nl less or equal to 1.50. This indicates
that for these stars a smaller value for alpha_nl is required than suggested
from a calibrated solar model. We stress the point that the linear stability
analysis used in this work still assumes stellar models without rotation and
that further developments are required for a proper description of the
interaction between rotation and pulsation dynamics.


title: Coulomb correlations do not fill the e'_g hole pockets in Na_{0.3}CoO_2

abstract:
  There exists presently considerable debate over the question whether local
Coulomb interactions can explain the absence of the small e'_g Fermi surface
hole pockets in photoemission studies of Na_{0.3}CoO_2. By comparing dynamical
mean field results for different single particle Hamiltonians and exact
diagonalization as well as quantum Monte Carlo treatments, we show that, for
realistic values of the Coulomb energy U and Hund exchange J, the e'_g pockets
can be slightly enhanced or reduced compared to band structure predictions, but
they do not disappear.


title: Hamilton-Jacobi Theory and Moving Frames

abstract:
  The interplay between the Hamilton-Jacobi theory of orthogonal separation of
variables and the theory of group actions is investigated based on concrete
examples.


title: On the Koplienko spectral shift function, I. Basics

abstract:
  We study the Koplienko Spectral Shift Function (KoSSF), which is distinct
from the one of Krein (KrSSF). KoSSF is defined for pairs $A,B$ with
$(A-B)\in\calI_2$, the Hilbert-Schmidt operators, while KrSSF is defined for
pairs $A,B$ with $(A-B)\in\calI_1$, the trace class operators. We review
various aspects of the construction of both KoSSF and KrSSF. Among our new
results are: (i) that any positive Riemann integrable function of compact
support occurs as a KoSSF; (ii) that there exist $A,B$ with $(A-B)\in\calI_2$
so $\det_2((A-z)(B-z)^{-1})$ does not have nontangential boundary values; (iii)
an alternative definition of KoSSF in the unitary case; and (iv) a new proof of
the invariance of the a.c. spectrum under $\calI_1$-perturbations that uses the
KrSSF.


title:
Light Front Formalism for Composite Systems and Some of Its Applications
  in Particle and Relativistic Nuclear Physics

abstract:
  Light front formalism for composite systems is presented. Derivation of
equations for bound state and scattering problems are given. Methods of
constructing of elastic form factors and scattering amplitudes of composite
particles are reviewed. Elastic form factors in the impulse approximation are
calculated. Scattering amplitudes for relativistic bound states are
constructed. Some model cases for transition amplitudes are considered. Deep
inelastic form factors (structure functions) are expressed through light front
wave functions. It is shown that taking into account of transverse motion of
partons leads to the violation of Bjorken scaling and structure functions
become square of transverse momentum dependent. Possible explanation of the
EMC-effect is given. Problem of light front relativization of wave functions of
lightest nuclei is considered. Scaling properties of deuteron, ${}^3He$ and
${}^4He$ light front wave functions are checked in a rather wide energy range.


title: Triple-loop networks with arbitrarily many minimum distance diagrams

abstract:
  Minimum distance diagrams are a way to encode the diameter and routing
information of multi-loop networks. For the widely studied case of double-loop
networks, it is known that each network has at most two such diagrams and that
they have a very definite form "L-shape''.
  In contrast, in this paper we show that there are triple-loop networks with
an arbitrarily big number of associated minimum distance diagrams. For doing
this, we build-up on the relations between minimum distance diagrams and
monomial ideals.


title: Arithmetic properties related to the shuffle-product

abstract:
  Properties of the shuffle product suggest the definition of a quadratic form
with domain and values in formal power series over a field of characteristic 2.
This quadratic form preserves rational (respectively algebraic) power series
and its restriction to the affine subspace of series with constant term 1 is
bijective. Conjecturally, this bijection restricts to a bijection of rational
(respectively algebraic) formal power series.


title: Burkholder's submartingales from a stochastic calculus perspective

abstract:
  We provide a simple proof, as well as several generalizations, of a recent
result by Davis and Suh, characterizing a class of continuous submartingales
and supermartingales that can be expressed in terms of a squared Brownian
motion and of some appropriate powers of its maximum. Our techniques involve
elementary stochastic calculus, as well as the Doob-Meyer decomposition of
continuous submartingales. These results can be used to obtain an explicit
expression of the constants appearing in the Burkholder-Davis-Gundy
inequalities. A connection with some balayage formulae is also established.


title: Impact of Cosmic Rays on Population III Star Formation

abstract:
  We explore the implications of a possible cosmic ray (CR) background
generated during the first supernova explosions that end the brief lives of
massive Population III stars. We show that such a CR background could have
significantly influenced the cooling and collapse of primordial gas clouds in
minihaloes around redshifts of z ~ 15 - 20, provided the CR flux was sufficient
to yield an ionization rate greater than about 10^-19 s^-1 near the center of
the minihalo. The presence of CRs with energies less than approximately 10^7 eV
would indirectly enhance the molecular cooling in these regions, and we
estimate that the resulting lower temperatures in these minihaloes would yield
a characteristic stellar mass as low as ~ 10 M_sun. CRs have a less pronounced
effect on the cooling and collapse of primordial gas clouds inside more massive
dark matter haloes with virial masses greater than approximately 10^8 M_sun at
the later stages of cosmological structure formation around z ~ 10 - 15. In
these clouds, even without CR flux the molecular abundance is already
sufficient to allow cooling to the floor set by the temperature of the cosmic
microwave background.


title:
First-Order Type Effects in YBa$_2$Cu$_3$O$_{6+x}$ at the Onset of
  Superconductivity

abstract:
  We present results of Raman scattering experiments on tetragonal ${\rm
(Y_{1-y}Ca_{y})Ba_{2}Cu_{3}O_{6+x}}$ for doping levels $p(x,y)$ between 0 and
0.07 holes/CuO$_2$. Below the onset of superconductivity at $p_{\rm sc1}
\approx 0.06$, we find evidence of a diagonal superstructure. At $p_{\rm sc1}$,
lattice and electron dynamics change discontinuously with the charge and spin
properties being renormalized at all energy scales. The results indicate that
charge ordering is intimately related to the transition at $p_{\rm sc1}$ and
that the maximal transition temperature to superconductivity at optimal doping
$T_{c}^{\rm max}$ depends on the type of ordering at $p>p_{\rm sc1}$.


title: Constraining Unparticle Physics with Cosmology and Astrophysics

abstract:
  It has recently been suggested that a scale invariant "unparticle" sector
with a non-trivial infrared fixed point may couple to the Standard Model (SM)
via higher dimensional operators. The weakness of such interactions hides the
the unparticle phenomena at low energies. We demonstrate how cosmology and
astrophysics can place significant bounds on the strength of unparticle-SM
interactions. We also discuss the possibility of a having a non-negligible
unparticle relic density today.


title: Unparticles and Muon Decay

abstract:
  Recently Georgi has discussed the possible existence of `Unparticles'
describable by operators having non-integral scaling dimensions. With the
interaction of these with the Standard Model (SM) particles being constrained
only by gauge and Lorentz symmetries, it affords a new source for lepton
flavour violation. Current and future muon decay experiments are shown to be
very sensitive to such scenarios.


title:
Discovery of Two Spectroscopically Peculiar, Low-Luminosity Quasars at
  z~4

abstract:
  We report the discovery of two low-luminosity quasars at z~4, both of which
show prominent N IV] 1486A emission. This line is extremely rare in quasar
spectra at any redshift; detecting it in two out of a sample of 23 objects
(i.e., ~ 9% of the sample) is intriguing and is likely due to the
low-luminosity, high-redshift quasar sample we are studying. This is still a
poorly explored regime, where contributions from associated, early starbursts
may be significant. One interpretation of this line posits photoionization by
very massive young stars. Seeing N IV] 1486A emission in a high-redshift quasar
may thus be understood in the context of co-formation and early co-evolution of
galaxies and their supermassive black holes. Alternatively, we may be seeing a
phenomenon related to the early evolution of quasar broad emission line
regions. The non-detection (and possibly even broad absorption) of N V 1240A
line in the spectrum of one of these quasars may support that interpretation.
These two objects may signal a new faint quasar population or an early AGN
evolutionary stage at high redshifts.


title: Prospects for the cavity-assisted laser cooling of molecules

abstract:
  Cooling of molecules via free-space dissipative scattering of photons is
thought not to be practicable due to the inherently large number of Raman loss
channels available to molecules and the prohibitive expense of building
multiple repumping laser systems. The use of an optical cavity to enhance
coherent Rayleigh scattering into a decaying cavity mode has been suggested as
a potential method to mitigate Raman loss, thereby enabling the laser cooling
of molecules to ultracold temperatures. We discuss the possibility of
cavity-assisted laser cooling particles without closed transitions, identify
conditions necessary to achieve efficient cooling, and suggest solutions given
experimental constraints. Specifically, it is shown that cooperativities much
greater than unity are required for cooling without loss, and that this could
be achieved via the superradiant scattering associated with intracavity
self-localization of the molecules. Particular emphasis is given to the polar
hydroxyl radical (OH), cold samples of which are readily obtained from Stark
deceleration.


title:
Critical Lieb-Thirring bounds for one-dimensional Schrodinger operators
  and Jacobi matrices with regular ground states

abstract:
  This paper has been withdrawn by the author in favor of a stronger result
proven by the author with R. Frank and T. Weidl in arXiv:0707.0998


title: Bubbles on Manifolds with a U(1) Isometry

abstract:
  We investigate the construction of five-dimensional, three-charge
supergravity solutions that only have a rotational U(1) isometry. We show that
such solutions can be obtained as warped compactifications with a singular
ambi-polar hyper-Kahler base space and singular warp factors. We show that the
complete solution is regular around the critical surface of the ambi-polar
base. We illustrate this by presenting the explicit form of the most general
supersymmetric solutions that can be obtained from an Atiyah-Hitchin base space
and its ambi-polar generalizations. We make a parallel analysis using an
ambi-polar generalization of the Eguchi-Hanson base space metric. We also show
how the bubbling procedure applied to the ambi-polar Eguchi-Hanson metric can
convert it to a global AdS_2xS^3 compactification.


title:
Isophotal Structure and Dust Distribution in Radio-Loud Elliptical
  Galaxies

abstract:
  We investigate isophotal properties and dust morphology in the nuclear
regions of 84 radio galaxies, imaged in the optical and near-infrared as part
of Hubble Space Telescope snapshot surveys. We present a sample-wide trend
between host galaxy isophotal structure and the inclination of dusty
circumnuclear disks at the centers of 13 of these objects. We find that
galaxies containing edge-on disks are invariably seen to possess boxy
isophotes, while round, face-on disks are seen exclusively in objects with
round or elliptical isophotes. Dust-rich sources with disky isophotes are
observed only to possess dust in the form of extended filamentary lanes, and
not in settled distributions like disks. As we do not expect that edge-on and
face-on disks reside in different populations of galaxies, we conclude that
perceived isophotal boxiness is dependent upon the angle at which the observer
views the host galaxy's axis of symmetry. We discuss our results in the context
of dissipative merger scenarios, and infer that dusty disks primarily reside in
old, boxy remnants of gas-poor galaxy mergers, whereas filamentary dust lanes
reside in younger disky remnants of gas-rich mergers.


title: Bayesian analysis of the low-resolution polarized 3-year WMAP sky maps

abstract:
  We apply a previously developed Gibbs sampling framework to the foreground
corrected 3-yr WMAP polarization data and compute the power spectrum and
residual foreground template amplitude posterior distributions. We first
analyze the co-added Q- and V-band data, and compare our results to the
likelihood code published by the WMAP team. We find good agreement, and thus
verify the numerics and data processing steps of both approaches. However, we
also analyze the Q- and V-bands separately, allowing for non-zero EB
cross-correlations and including two individual foreground template amplitudes
tracing synchrotron and dust emission. In these analyses, we find tentative
evidence of systematics: The foreground tracers correlate with each of the Q-
and V-band sky maps individually, although not with the co-added QV map; there
is a noticeable negative EB cross-correlation at l <~ 16 in the V-band map; and
finally, when relaxing the constraints on EB and BB, noticeable differences are
observed between the marginalized band powers in the Q- and V-bands. Further
studies of these features are imperative, given the importance of the low-l EE
spectrum on the optical depth of reionization tau and the spectral index of
scalar perturbations n_s.


title: Subjective Information Measure and Rate Fidelity Theory

abstract:
  Using fish-covering model, this paper intuitively explains how to extend
Hartley's information formula to the generalized information formula step by
step for measuring subjective information: metrical information (such as
conveyed by thermometers), sensory information (such as conveyed by color
vision), and semantic information (such as conveyed by weather forecasts). The
pivotal step is to differentiate condition probability and logical condition
probability of a message. The paper illustrates the rationality of the formula,
discusses the coherence of the generalized information formula and Popper's
knowledge evolution theory. For optimizing data compression, the paper
discusses rate-of-limiting-errors and its similarity to complexity-distortion
based on Kolmogorov's complexity theory, and improves the rate-distortion
theory into the rate-fidelity theory by replacing Shannon's distortion with
subjective mutual information. It is proved that both the rate-distortion
function and the rate-fidelity function are equivalent to a
rate-of-limiting-errors function with a group of fuzzy sets as limiting
condition, and can be expressed by a formula of generalized mutual information
for lossy coding, or by a formula of generalized entropy for lossless coding.
By analyzing the rate-fidelity function related to visual discrimination and
digitized bits of pixels of images, the paper concludes that subjective
information is less than or equal to objective (Shannon's) information; there
is an optimal matching point at which two kinds of information are equal; the
matching information increases with visual discrimination (defined by confusing
probability) rising; for given visual discrimination, too high resolution of
images or too much objective information is wasteful.


title: Dynamics of interacting Brownian particles: a diagrammatic formulation

abstract:
  We present a diagrammatic formulation of a theory for the time dependence of
density fluctuations in equilibrium systems of interacting Brownian particles.
To facilitate derivation of the diagrammatic expansion we introduce a basis
that consists of orthogonalized many-particle density fluctuations. We obtain
an exact hierarchy of equations of motion for time-dependent correlations of
orthogonalized density fluctuations. To simplify this hierarchy we neglect
contributions to the vertices from higher-order cluster expansion terms. An
iterative solution of the resulting equations can be represented by diagrams
with three and four-leg vertices. We analyze the structure of the diagrammatic
series for the time-dependent density correlation function and obtain a
diagrammatic interpretation of reducible and irreducible memory functions. The
one-loop self-consistent approximation for the latter function coincides with
mode-coupling approximation for Brownian systems that was derived previously
using a projection operator approach.


title:
Eigenvalue bounds in the gaps of Schrodinger operators and Jacobi
  matrices

abstract:
  We consider $C=A+B$ where $A$ is selfadjoint with a gap $(a,b)$ in its
spectrum and $B$ is (relatively) compact. We prove a general result allowing
$B$ of indefinite sign and apply it to obtain a $(\delta V)^{d/2}$ bound for
perturbations of suitable periodic Schrodinger operators and a (not
quite)Lieb-Thirring bound for perturbations of algebro-geometric almost
periodic Jacobi matrices.


title: The Baryon Fractions and Mass-to-Light Ratios of Early-Type Galaxies

abstract:
  We jointly model 22 early-type gravitational lens galaxies with stellar
dynamical measurements using standard CDM halo models. The sample is
inhomogeneous in both its mass distributions and the evolution of its stellar
populations unless the true uncertainties are significantly larger than the
reported measurement errors. In general, the individual systems cannot
constrain halo models, in the sense that the data poorly constrains the stellar
mass fraction of the halo. The ensemble of systems, however, strongly
constrains the average stellar mass represented by the visible galaxies to
$0.026\pm0.006$ of the halo mass if we neglect adiabatic compression, rising to
$0.056\pm0.011$ of the halo mass if we include adiabatic compression. Both
estimates are significantly smaller than the global baryon fraction,
corresponding to a star formation efficiency for early-type galaxies of
$10%-30%$. In the adiabatically compressed models, we find an average local
B-band stellar mass-to-light ratio of $(M/L)_0 =
(7.2\pm0.5)(M_{\sun}/L_{\sun})$ that evolves by $d\log(M/L)/dz = -0.72\pm0.08$
per unit redshift. Adjusting the isotropy of the stellar orbits has little
effect on the results. The adiabatically compressed models are strongly favored
if we impose either local estimates of the mass-to-light ratios of early-type
galaxies or the weak lensing measurements for the lens galaxies on 100 kpc
scales as model constraints.


title: Energy Transfer between Throats from a 10d Perspective

abstract:
  Strongly warped regions, also known as throats, are a common feature of the
type IIB string theory landscape. If one of the throats is heated during
cosmological evolution, the energy is subsequently transferred to other throats
or to massless fields in the unwarped bulk of the Calabi-Yau orientifold. This
energy transfer proceeds either by Hawking radiation from the black hole
horizon in the heated throat or, at later times, by the decay of
throat-localized Kaluza-Klein states. In both cases, we calculate in a 10d
setup the energy transfer rate (respectively decay rate) as a function of the
AdS scales of the throats and of their relative distance. Compared to existing
results based on 5d models, we find a significant suppression of the energy
transfer rates if the size of the embedding Calabi-Yau orientifold is much
larger than the AdS radii of the throats. This effect can be partially
compensated by a small distance between the throats. These results are
relevant, e.g., for the analysis of reheating after brane inflation. Our
calculation employs the dual gauge theory picture in which each throat is
described by a strongly coupled 4d gauge theory, the degrees of freedom of
which are localized at a certain position in the compact space.


title:
On the origin of kinematic distribution of the sub-parsec young stars in
  the Galactic center

abstract:
  Within a half-parsec from the Galactic center (GC), there is a population of
coeval young stars which appear to reside in a coherent disk. Surrounding this
dynamically-cool stellar system, there is a population of stars with a similar
age and much larger eccentricities and inclinations relative to the disk. We
propose a hypothesis for the origin of this dynamical dichotomy. Without
specifying any specific mechanism, we consider the possibility that both
stellar populations were formed within a disk some 6 Myr ago. But this orderly
structure was dynamically perturbed outside-in by an intruding object with a
mass ~10^4 Msun, which may be an intermediate-mass black hole (IMBH) or a dark
stellar cluster hosting an IMBH. We suggest that the perturber migrated inward
to ~0.15-0.3pc from the GC under the action of dynamical friction. Along the
way, it captured many stars in the outer disk region into its mean-motion
resonance, forced them to migrate with it, closely encountered with them, and
induced the growth of their eccentricity and inclination. But stars in the
inner regions of the disk retain their initial coplanar structure. We predict
that some of the inclined and eccentric stars surrounding the disk may have
similar Galactocentric semimajor axis. Future precision determination of their
kinematic distribution of these stars will not only provide a test for this
hypothesis but also evidences for the presence of an IMBH or a dark cluster at
the immediate proximity of the massive black hole at the GC. (abridged)


title: Implications of D^0-\bar D^0 Mixing for New Physics

abstract:
  We provide a comprehensive, up-to-date analysis of possible New Physics
contributions to the mass difference $\Delta M_D$ in $D^0$-${\bar D}^0$ mixing.
We consider the most general low energy effective Hamiltonian and include
leading order QCD running of effective operators. We then explore an extensive
list of possible New Physics models that can generate these operators, which we
organize as including Extra Fermions, Extra Gauge Bosons, Extra Scalars, Extra
Space Dimensions and Extra Symmetries. For each model we place restrictions on
the allowed parameter space using the recent evidence for observation of $D$
meson mixing. In many scenarios, we find strong constraints that surpass those
from other search techniques and provide an important test of flavor changing
neutral currents in the up-quark sector. We also review the recent BaBar and
Belle findings, and describe the current status of the Standard Model
predictions of $D^0$-${\bar D}^0$ mixing.


title:
Computing parametric rational generating functions with a primal
  Barvinok algorithm

abstract:
  Computations with Barvinok's short rational generating functions are
traditionally being performed in the dual space, to avoid the combinatorial
complexity of inclusion--exclusion formulas for the intersecting proper faces
of cones. We prove that, on the level of indicator functions of polyhedra,
there is no need for using inclusion--exclusion formulas to account for
boundary effects: All linear identities in the space of indicator functions can
be purely expressed using half-open variants of the full-dimensional polyhedra
in the identity. This gives rise to a practically efficient, parametric
Barvinok algorithm in the primal space.


title:
Chi2 and chi3 harmonic generation at a critical power in inhomogeneous
  doubly resonant cavities

abstract:
  We derive general conditions for 100 percent frequency conversion in any
doubly resonant nonlinear cavity, for both second- and third-harmonic
generation via chi2 and chi3 nonlinearities. We find that conversion efficiency
is optimized for a certain critical power depending on the cavity parameters,
and assuming reasonable parameters we predict 100 percent conversion using
milliwatts of power or less. These results follow from a semi-analytical
coupled-mode theory framework which is generalized from previous work to
include both chi2 and chi3 media as well as inhomogeneous (fully vectorial)
cavities, analyzed in the high-efficiency limit where down-conversion processes
lead to a maximum efficiency at the critical power, and which is verified by
direct finite-difference time-domain (FDTD) simulations of the nonlinear
Maxwell equations. Explicit formulas for the nonlinear coupling coefficients
are derived in terms of the linear cavity eigenmodes, which can be used to
design and evaluate cavities in arbitrary geometries.


title: Mott Fermionic "Quantum" Criticality Beyond Ginzburg-Landau-Wilson

abstract:
  The Mott critical point between a metal and a correlated insulator has
usually been studied via density or spin density bosonic mode fluctuations
according to the standard Ginzburg-Landau-Wilson phase transition paradigm. A
moment's reflection leads to increasing doubts that such an approach should
work as the transition is nonmagnetic, voiding the relevance of spin density
modes. Charge density modes are irrelevelant since the long range Coulomb
interaction leads to a large plasmon gap and their incompressibility. In
solidarity with these doubts, recent measurements of the Mott critical point in
low dimensional organic materials yield critical exponents in violent
diasagreement with the bosonic mode criticality lore. We propose that fermionic
fluctuations control the behavior of the Mott transition. The transition thus
has an intrinsic quantum aspect despite being a finite temperature phase
transition. We develop this hitherto unexplored physics, obtain experimental
predictions and find agreement with one of the novel unexplained experimental
exponents. We conclude that this Mott transition corresponds to a new
universality class of finite temperature critical points that contains quantum
effects and cannot be accounted for by conventional Ginzburg-Landau-Wilson
wisdom.


title:
Nonequilibrium Dynamics of Anisotropic Large Spins in the Kondo Regime:
  Time-Dependent Numerical Renormalization Group Analysis

abstract:
  We investigate the time-dependent Kondo effect in a single-molecule magnet
(SMM) strongly coupled to metallic electrodes. Describing the SMM by a Kondo
model with large spin S > 1/2, we analyze the underscreening of the local
moment and the effect of anisotropy terms on the relaxation dynamics of the
magnetization. Underscreening by single-channel Kondo processes leads to a
logarithmically slow relaxation, while finite uniaxial anisotropy causes a
saturation of the SMM's magnetization. Additional transverse anisotropy terms
induce quantum spin tunneling and a pseudospin-1/2 Kondo effect sensitive to
the spin parity.


title: Evidence Of Dark Matter Annihilations In The WMAP Haze

abstract:
  The WMAP experiment has revealed an excess of microwave emission from the
region around the center of our Galaxy. It has been suggested that this signal,
known as the ``WMAP Haze'', could be synchrotron emission from relativistic
electrons and positrons generated in dark matter annihilations. In this letter,
we revisit this possibility. We find that the angular distribution of the WMAP
Haze matches the prediction for dark matter annihilations with a cusped density
profile, $\rho(r) \propto r^{-1.2}$ in the inner kiloparsecs. Comparing the
intensity in different WMAP frequency bands, we find that a wide range of
possible WIMP annihilation modes are consistent with the spectrum of the haze
for a WIMP with a mass in the 100 GeV to multi-TeV range. Most interestingly,
we find that to generate the observed intensity of the haze, the dark matter
annihilation cross section is required to be approximately equal to the value
needed for a thermal relic, $\sigma v \sim 3 \times 10^{-26}$ cm$^3$/s. No
boost factors are required. If dark matter annihilations are in fact
responsible for the WMAP Haze, and the slope of the halo profile continues into
the inner Galaxy, GLAST is expected to detect gamma rays from the dark matter
annihilations in the Galactic Center if the WIMP mass is less than several
hundred GeV.


title: The Elementary Particles as Quantum Knots in Electroweak Theory

abstract:
  We explore a knot model of the elementary particles that is compatible with
electroweak physics. The knots are quantized and their kinematic states are
labelled by $D^j_{mm'}$, irreducible representations of $SU_q(2)$, where j =
N/2, m = w/2, m' = (r+1)/2 and (N,w,r) designate respectively the number of
crossings, the writhe, and the rotation of the knot. The knot quantum numbers
(N,w,r) are related to the standard isotopic spin quantum numbers $(t,t_3,t_0)$
by $(t=N/6,t_3=-w/6,t_0=-(r+1)/6)$, where $t_0$ is the hypercharge. In this
model the elementary fermions are low lying states of the quantum trefoil (N=3)
and the gauge bosons are ditrefoils (N=6). The fermionic knots interact by the
emission and absorption of bosonic knots. In this framework we have explored a
slightly modified standard electroweak Lagrangian with a slightly modified
gauge group which agrees closely but not entirely with standard electroweak
theory.


title: Separation of Bell states

abstract:
  The four Bell states can be represented by separable coherent states which
are products of individual non-hermitian spin operators. In the absence of
interactions, the non-hermitian states are predicted to form a new quantum
state of spin magnitude 1/sqrt(2) rather than 1/2. Properties of these states
show that an isolated spin is a resonance state with zero net angular momentum,
consistent with a point particle. In addition, the Bell states are shown to
take on the identical mathematical form when the two spins are bound (local) or
unbound (non-local). The bound Bell states are resonances between four states.
When the separate, they do so from only one of its resonance states and their
ensemble average defines the unbound Bell states. The bound and unbound Bell
states have the same mathematical form due to the persistence of the
rotationally invariance of sigma(1)dot sigma(2).


title: Picard-Fuchs Differential Equations for Families of K3 Surfaces

abstract:
  This thesis studies some examples of families of K3 surfaces with Picard
lattices of maximal rank. These families occur as invariants of finite
automorphism groups. The Picard-Fuchs differential equations describing the
variation of Hodge structure in these families are considered. Techniques are
developed to find the corresponding monodromy groups as arithmetic Fuchsian
groups acting on the families' period spaces.


title: Log improvement of the Prodi-Serrin criteria for Navier-Stokes equations

abstract:
  This article is devoted to a Log improvement of Prodi-Serrin criterion for
global regularity to solutions to Navier-Stokes equations in dimension 3. It is
shown that the global regualrity holds under the condition that |u|^5/ log
(1+|u|) is integrable in space time variables.


title: Fluctuation-dissipation ratios in the dynamics of self-assembly

abstract:
  We consider two seemingly very different self-assembly processes: formation
of viral capsids, and crystallization of sticky discs. At low temperatures,
assembly is ineffective, since there are many metastable disordered states,
which are a source of kinetic frustration. We use fluctuation-dissipation
ratios to extract information about the degree of this frustration. We show
that our analysis is a useful indicator of the long term fate of the system,
based on the early stages of assembly.


title:
Virtual photons in imaginary time: Computing exact Casimir forces via
  standard numerical-electromagnetism techniques

abstract:
  We describe a numerical method to compute Casimir forces in arbitrary
geometries, for arbitrary dielectric and metallic materials, with arbitrary
accuracy (given sufficient computational resources). Our approach, based on
well-established integration of the mean stress tensor evaluated via the
fluctuation-dissipation theorem, is designed to directly exploit fast methods
developed for classical computational electromagnetism, since it only involves
repeated evaluation of the Green's function for imaginary frequencies
(equivalently, real frequencies in imaginary time). We develop the approach by
systematically examining various formulations of Casimir forces from the
previous decades and evaluating them according to their suitability for
numerical computation. We illustrate our approach with a simple
finite-difference frequency-domain implementation, test it for known geometries
such as a cylinder and a plate, and apply it to new geometries. In particular,
we show that a piston-like geometry of two squares sliding between metal walls,
in both two and three dimensions with both perfect and realistic metallic
materials, exhibits a surprising non-monotonic ``lateral'' force from the
walls.


title:
Molecular gas in NUclei of GAlaxies (NUGA) VII. NGC4569, a large scale
  bar funnelling gas into the nuclear region

abstract:
  This work is part of the NUGA survey of CO emission in nearby active
galaxies. We present observations of NGC4569, a member of the Virgo Cluster. We
analyse the molecular gas distribution and kinematics in the central region and
we investigate a possible link to the strong starburst present at the nucleus.
70% of the 1.1x10^9 Msolar of molecular gas detected in the inner 20" is found
to be concentrated within the inner 800 pc and is distributed along the large
scale stellar bar seen in near-infrared observations. A hole in the CO
distribution coincides with the nucleus where most of the Halpha emission and
blue light are emitted. The kinematics are modelled in three different ways,
ranging from the purely geometrical to the most physical. This approach allows
us to constrain progressively the physical properties of the galaxy and
eventually to emerge with a reasonable fit to an analytical model of orbits in
a barred potential. Fitting an axisymmetric model shows that the non-circular
motions must be comparable in amplitude to the circular motions (120 km/s).
Fitting a model based on elliptical orbits allows us to identify with
confidence the single inner Lindblad resonance (ILR) of the large scale bar.
Finally, a model based on analytical solutions for the gas particle orbits in a
weakly barred potential constrained by the ILR radius reproduces the
observations well. The mass inflow rate is then estimated and discussed based
on the best fit model solution. The gravitational torques implied by this model
are able to efficiently funnel the gas inside the ILR down to 300 pc, although
another mechanism must take over to fuel the nuclear starburst inside 100 pc.


title: Vaporization and Layering of Alkanols at the Oil/Water Interface

abstract:
  This study of adsorption of normal alkanols at the oil/water interface with
x-ray reflectivity and tensiometry demonstrates that the liquid to gas
monolayer phase transition at the hexane/water interface is thermodynamically
favorable only for long-chain alkanols. As the alkanol chain length is
decreased, the change in excess interfacial entropy per area decreases to zero.
Systems with small values of excess interfacial entropy form multi-molecular
layers at the interface instead of the monolayer formed by systems with much
larger excess interfacial entropy. Substitution of n-hexane by n-hexadecane
significantly alters the interfacial structure for a given alkanol surfactant,
but this substitution does not change fundamentally the phase transition
behavior of the monolayers. These data show that the critical alkanol carbon
number, at which the change in excess interfacial entropy per area decreases to
zero, is approximately six carbons larger than the number of carbons in the
alkane solvent molecules.


title: A LLT-like test for proving the primality of Fermat numbers

abstract:
  This paper provides a proof of a LLT-like test for Fermat numbers, based on
the properties of Lucas Sequences and on the method of Lehmer.


title:
An array of low-background $^3$He proportional counters for the Sudbury
  Neutrino Observatory

abstract:
  An array of Neutral-Current Detectors (NCDs) has been built in order to make
a unique measurement of the total active flux of solar neutrinos in the Sudbury
Neutrino Observatory (SNO). Data in the third phase of the SNO experiment were
collected between November 2004 and November 2006, after the NCD array was
added to improve the neutral-current sensitivity of the SNO detector. This
array consisted of 36 strings of proportional counters filled with a mixture of
$^3$He and CF$_4$ gas capable of detecting the neutrons liberated by the
neutrino-deuteron neutral current reaction in the D$_2$O, and four strings
filled with a mixture of $^4$He and CF$_4$ gas for background measurements. The
proportional counter diameter is 5 cm. The total deployed array length was 398
m. The SNO NCD array is the lowest-radioactivity large array of proportional
counters ever produced. This article describes the design, construction,
deployment, and characterization of the NCD array, discusses the electronics
and data acquisition system, and considers event signatures and backgrounds.


title: Signatures of incoherence in a quantum information processor

abstract:
  Incoherent noise is manifest in measurements of expectation values when the
underlying ensemble evolves under a classical distribution of unitary
processes. While many incoherent processes appear decoherent, there are
important differences. The distribution functions underlying incoherent
processes are either static or slowly varying with respect to control
operations and so the errors introduced by these distributions are refocusable.
The observation and control of incoherence in small Hilbert spaces is well
known. Here we explore incoherence during an entangling operation, such as is
relevant in quantum information processing. As expected, it is more difficult
to separate incoherence and decoherence over such processes. However, by
studying the fidelity decay under a cyclic entangling map we are able to
identify distinctive experimental signatures of incoherence. This result is
demonstrated both through numerical simulations and experimentally in a three
qubit nuclear magnetic resonance implementation.


title:
Classification of singularities in the complete conformally flat Yamabe
  flow

abstract:
  We show that an eternal solution to a complete, locally conformally flat
Yamabe flow, $\frac{\partial}{\partial t} g = -Rg$, with uniformly bounded
scalar curvature and positive Ricci curvature at $t = 0$, where the scalar
curvature assumes its maximum is a gradient steady soliton. As an application
of that, we study the blow up behavior of $g(t)$ at the maximal time of
existence, $T < \infty$. We assume that $(M,g(\cdot, t))$ satisfies (i) the
injectivity radius bound {\bf or} (ii) the Schouten tensor is positive at time
$t = 0$ and the scalar curvature bounded at each time-slice. We show that the
singularity the flow develops at time $T$ is always of type I.


title: An unusually brilliant transient in the galaxy Messier 85

abstract:
  Historically, variable and transient sources have both surprised astronomers
and provided new views of the heavens. Here we report the discovery of an
optical transient in the outskirts of the lenticular galaxy Messier 85 in the
Virgo Cluster. With a peak absolute R magnitude of -12 this event is distinctly
brighter than novae, but fainter than type Ia supernovae (expected from a
population of old stars in lenticular galaxies). Archival images of the field
do not show a luminous star at that position with an upper limit of ~-4.1, so
it is unlikely to be a giant eruption from a luminous blue variable star. Over
a two month period the transient emitted radiation energy of almost 10E47 erg
and subsequently faded in the opical sky. It is similar to, but more luminous
at peak by a factor of 6 than, an enigmatic transient in the galaxy M31. A
possible origin of M85 OT2006-1 is a stellar merger. If so, searches for
similar events in nearby galaxies will not only allow to study the physics of
hyper-Eddington sources, but also probe an important phase in the evolution of
stellar binary systems.


title:
Structural Health Monitoring Using Neural Network Based Vibrational
  System Identification

abstract:
  Composite fabrication technologies now provide the means for producing
high-strength, low-weight panels, plates, spars and other structural components
which use embedded fiber optic sensors and piezoelectric transducers. These
materials, often referred to as smart structures, make it possible to sense
internal characteristics, such as delaminations or structural degradation. In
this effort we use neural network based techniques for modeling and analyzing
dynamic structural information for recognizing structural defects. This yields
an adaptable system which gives a measure of structural integrity for composite
structures.


title: Guiding-center solitons in rotating potentials

abstract:
  We demonstrate that rotating quasi-one-dimensional potentials, periodic or
parabolic, support solitons in settings where they are otherwise impossible.
Ground-state and vortex solitons are found in defocusing media, if the rotation
frequency exceeds a critical value. The revolving periodic potentials exhibit
the strongest stabilization capacity at a finite optimum value of their
strength, while the rotating parabolic trap features a very sharp transition to
stability with the increase of rotation frequency.


title:
Asymptotic Behavior of the Newton-Boussinesq Equation in a
  Two-Dimensional Channel

abstract:
  We prove the existence of a global attractor for the Newton-Boussinesq
equation defined in a two-dimensional channel. The asymptotic compactness of
the equation is derived by the uniform estimates on the tails of solutions. We
also establish the regularity of the global attractor.


title: Saturation QCD predictions with heavy quarks at HERA

abstract:
  The measurement of the proton structure function at HERA is often seen as a
hint for the observation of saturation in high-energy QCD e.g. through the
observation of geometric scaling. Accordingly, the dipole picture provides a
powerful framework in which the QCD-based saturation models can be confronted
to the data. In this paper, we give a parametrisation of proton structure
function which is directly constrained by the dynamics of QCD in its
high-energy limit and fully includes the heavy quark effects. We obtain a good
agreement with the available data. Furthermore, to the contrary of various
models in the literature, we do not observe a significant decrease of the
saturation momentum due to the heavy quark inclusion.


title:
Differential inequalities for Riesz means and Weyl-type bounds for
  eigenvalues

abstract:
  We derive differential inequalities and difference inequalities for Riesz
means of eigenvalues of the Dirichlet Laplacian,
  R_{\sigma}(z) := \sum_k{(z -\lambda_k)_+^{\sigma}}.
  Here ${\lambda_k}_{k=1}^{\infty}$ are the ordered eigenvalues of the
Laplacian on a bounded domain $\Omega \subset \R^d$, and $x_+ := \max(0, x)$
denotes the positive part of the quantity $x$. As corollaries of these
inequalities, we derive Weyl-type bounds on $\lambda_k$, on averages such as
$\bar{\lambda_k} := {\frac 1 k}\sum_{\ell \le k}\lambda_\ell$, and on the
eigenvalue counting function. For example, we prove that for all domains and
all $k \ge j \frac{1+\frac d 2}{1+\frac d 4}$,
  {\bar{\lambda_{k}}}/{\bar{\lambda_{j}}} \le 2 (\frac{1+\frac d 4}{1+\frac d
2})^{1+\frac 2 d}({\frac k j})^{\frac 2 d}.


title:
Existence of Infinitely Many Solutions for a Quasilinear Elliptic
  Problem on Time Scales

abstract:
  We study a boundary-value quasilinear elliptic problem on a generic time
scale. Making use of the fixed-point index theory, sufficient conditions are
given to obtain existence, multiplicity, and infinite solvability of positive
solutions.


title:
Phase Change Observed in Ultrathin Ba0.5Sr0.5TiO3 Films by in-situ
  Resonant Photoemission Spectroscopy

abstract:
  Epitaxial Ba0.5Sr0.5TiO3 thin films were prepared on Nb-doped SrTiO3
(100)substrates by the pulsed laser deposition technique, and were studied by
measuring the Ti 2p - 3d resonant photoemission spectra in the valence-band
region as a function of film thickness, both at room temperature and low
temperature. Our results demonstrated an abrupt variation in the spectral
structures between 2.8 nm (~7 monolayers) and 2.0 nm (~5 monolayers)
Ba0.5Sr0.5TiO3 films, suggesting that there exists a critical thickness for
phase change in the range of 2.0 nm to 2.8 nm. This may be ascribed mainly to
the intrinsic size effects.


title:
Atlas of two-dimensional irreversible conservative lagrangian mechanical
  systems with a second quadratic integral

abstract:
  This paper aims at the most comprehensive and systematic construction and
tabulation of mechanical systems that admit a second invariant, quadratic in
velocities, other than the Hamiltonian. The configuration space is in general a
2D Riemannian or pseudo-Riemannian manifold and the determination of its
geometry is a part of the process of solution. Forces acting on the system
include a part derived from a scalar potential and a part derived from a vector
potential, associated with terms linear in velocities in the Lagrangian
function of the system. The last cause time-irreversibility of the system. We
construct 41 multi-parameter integrable systems of the type described in the
title mostly on Riemannian manifolds. They are mostly new and cover all
previously known systems as special cases, corresponding to special values of
the parameters. Those include all known cases of motion of a particle in the
plane and all known cases in the dynamics of rigid body. In the last field we
introduce a new integrable case related to Steklov's case of motion of a body
in a liquid. Several new cases of motion in the plane, on the sphere and on the
pseudo-sphere or in the hyperbolic plane are found as special cases.
Prospective applications in mathematics and physics are also pointed out.


title: Distributed Transmit Diversity in Relay Networks

abstract:
  We analyze fading relay networks, where a single-antenna source-destination
terminal pair communicates through a set of half-duplex single-antenna relays
using a two-hop protocol with linear processing at the relay level. A family of
relaying schemes is presented which achieves the entire optimal
diversity-multiplexing (DM) tradeoff curve. As a byproduct of our analysis, it
follows that delay diversity and phase-rolling at the relay level are optimal
with respect to the entire DM-tradeoff curve, provided the delays and the
modulation frequencies, respectively, are chosen appropriately.


title:
Magnetically-driven explosions of rapidly-rotating white dwarfs
  following Accretion-Induced Collapse

abstract:
  We present 2D multi-group flux-limited diffusion magnetohydrodynamics (MHD)
simulations of the Accretion-Induced Collapse (AIC) of a rapidly-rotating white
dwarf. We focus on the dynamical role of MHD processes after the formation of a
millisecond-period protoneutron star. We find that including magnetic fields
and stresses can lead to a powerful explosion with an energy of a few Bethe,
rather than a weak one of at most 0.1 Bethe, with an associated ejecta mass of
~0.1Msun, instead of a few 0.001Msun. The core is spun down by ~30% within
500ms after bounce, and the rotational energy extracted from the core is
channeled into magnetic energy that generates a strong magnetically-driven
wind, rather than a weak neutrino-driven wind. Baryon loading of the ejecta,
while this wind prevails, precludes it from becoming relativistic. This
suggests that a GRB is not expected to emerge from such AICs during the early
protoneutron star phase, except in the unlikely event that the massive white
dwarf has sufficient mass to lead to black hole formation. In addition, we
predict both negligible 56Ni-production (that should result in an
optically-dark, adiabatically-cooled explosion) and the ejection of 0.1Msun of
material with an electron fraction of 0.1-0.2. Such pollution by neutron-rich
nuclei puts strong constraints on the possible rate of such AICs. Moreover,
being free from ``fallback,'' such highly-magnetized millisecond-period
protoneutron stars may later become magnetars, and the magnetically-driven
winds may later transition to Poynting-flux-dominated, relativistic winds,
eventually detectable as GRBs at cosmological distances. However, the low
expected event rate of AICs will constrain them to be, at best, a small subset
of GRB and/or magnetar progenitors.


title:
Transient dynamics for sequence processing neural networks: effect of
  degree distributions

abstract:
  We derive a analytic evolution equation for overlap parameters including the
effect of degree distribution on the transient dynamics of sequence processing
neural networks. In the special case of globally coupled networks, the
precisely retrieved critical loading ratio $\alpha_c = N ^{-1/2}$ is obtained,
where $N$ is the network size. In the presence of random networks, our
theoretical predictions agree quantitatively with the numerical experiments for
delta, binomial, and power-law degree distributions.


title:
Quantitative determination of the Hubbard model phase diagram from
  optical lattice experiments by two-parameter scaling

abstract:
  We propose an experiment to obtain the phase diagram of the fermionic Hubbard
model, for any dimensionality, using cold atoms in optical lattices. It is
based on measuring the total energy for a sequence of trap profiles. It
combines finite-size scaling with an additional `finite-curvature scaling'
necessary to reach the homogeneous limit. We illustrate its viability in the 1D
case, simulating experimental data in the Bethe-Ansatz local density
approximation. Including experimental errors, the filling corresponding to the
Mott transition can be determined with better than 3% accuracy.