title: Parity-Violating Nuclear Force as derived from QCD Sum Rules

abstract:
  Parity-violating nuclear force, as may be accessed from parity violation
studies in nuclear systems, represents an area of nonleptonic weak interactions
which has been the subject of experimental investigations for several decades.
In the simple meson-exchange picture, parity-violating nuclear force may be
parameterized as arising from exchange of \pi, \rho, \omega, or other meson(s)
with strong meson-nucleon coupling at one vertex and weak parity-violating
meson-nucleon coupling at the other vertex. The QCD sum rule method allows for
a fairly complicated, but nevertheless straightforward, leading-order
loop-contribution determination of the various parity-violating MNN couplings
starting from QCD (with the nontrivial vacuum) and Glashow-Salam-Weinberg
electroweak theory. We continue our earlier investigation of parity-violating
\pi NN coupling (by Henley, Hwang, and Kisslinger) to other parity-violating
couplings. Our predictions are in reasonable overall agreement with the results
estimated on phenomenological grounds, such as in the now classic paper of
Desplanques, Donoghue, and Holstein (DDH), in the global experimental fit of
Adelberger and Haxton (AH), or the effective field theory (EFT) thinking of
Ramsey-Musolf and Page (RP).


title: Hyperbolic mean curvature flow: Evolution of plane curves

abstract:
  In this paper we investigate the one-dimensional hyperbolic mean curvature
flow for closed plane curves. We show that there exists a class of initial
velocities such that the solution of the corresponding initial value problem
exists only at a finite time interval $[0,T_{\max})$ and when $t$ goes to
$T_{\max}$, the solution converges to a point. We also discuss the close
relationship between the hyperbolic mean curvature flow and the equations for
the evolving relativistic string in the Minkowski space-time
$\mathbb{R}^{1,1}$.


title: SETI and muon collider

abstract:
  Intense neutrino beams that accompany muon colliders can be used for
interstellar communications. The presence of multi-TeV extraterrestrial muon
collider at several light-years distance can be detected after one year run of
IceCube type neutrino telescopes, if the neutrino beam is directed towards the
Earth. This opens a new avenue in SETI: search for extraterrestrial muon
colliders.


title: Expanding color flux tubes and instabilities

abstract:
  We present an analytic study of the physics of the glasma which is a strong
classical gluon field created at early stage of high-energy heavy-ion
collisions. Our analysis is based on the picture that the glasma just after the
collision is made of color electric and magnetic flux tubes extending in the
longitudinal direction with their diameters of the order of 1/Q_s (Q_s is the
saturation scale of the colliding nuclei). We find that both the electric and
magnetic flux tubes expand outwards and the field strength inside the flux tube
decays rapidly in time. Next we investigate whether there exist instabilities
against small rapidity-dependent perturbations for a fixed color configuration.
We find that the magnetic background field exhibits an instability induced by
the fluctuations in the lowest Landau level, and it grows in the time scale of
1/Q_s. For the electric background field we find no apparent instability while
the possible relation to the Schwinger mechanism for particle pair creations is
suggested.


title: New Semifield Planes of order 81

abstract:
  A finite semifield is a finite nonassociative ring with identity such that
the set of its nonzero elements is closed under the product. From any finite
semifield a projective plane can be constructed. In this paper we obtain new
semifield planes of orders 81 by means of computational methods. These
computer-assisted results yield to a complete classification (up to isotopy) of
81-element finite semifields.


title: Essential conditions for evolution of communication within a species

abstract:
  A major obstacle in analyzing the evolution of information exchange and
processing is our insufficient understanding of the underlying signaling and
decision-making biological mechanisms. For instance, it is unclear why are
humans unique in developing such extensive communication abilities. To treat
this problem, a method based on the mutual information approach is developed
that evaluates the information content of communication between interacting
individuals through correlations of their behavior patterns (rather than
calculating the information load of exchanged discrete signals, e.g. Shannon
entropy). It predicts that correlated interactions of the indirect reciprocity
type together with affective behavior and selection rules changing with time
are necessary conditions for the emergence of significant information exchange.
Population size variations accelerate this development. These results are
supported by evidence of demographic bottlenecks, distinguishing human from
other species' (e.g. apes) evolution line. They indicate as well new pathways
for evolution of information based phenomena, such as intelligence and
complexity.


title: The Mahler measure and the L-series of a singular K3-surface

abstract:
  We present the first example of a polynomial defining a singular K3-surface
whose Mahler measure is expressed in terms of the Mahler measure of the faces
of its Newton polyhedron and the L-series of the K3-surface.


title:
Star formation history of galaxies from z=0 to z=0.7 A backward approach
  to the evolution of star-forming galaxies

abstract:
  We investigate whether the mean star formation activity of star-forming
galaxies from z=0 to z=0.7 in the GOODS-S field can be reproduced by simple
evolution models of these systems. In this case, such models might be used as
first order references for studies at higher z to decipher when and to what
extent a secular evolution is sufficient to explain the star formation history
in galaxies.
  We selected star-forming galaxies at z=0 and at z=0.7 in IR and in UV to have
access to all the recent star formation. We focused on galaxies with a stellar
mass ranging between 10^{10} and 10^{11} M_sun for which the results are not
biased by the selections. We compared the data to chemical evolution models
developed for spiral galaxies and originally built to reproduce the main
characteristics of the Milky Way and nearby spirals without fine-tuning them
for the present analysis. We find a shallow decrease in the specific star
formation rate (SSFR) when the stellar mass increases. The evolution of the
SSFR characterizing both UV and IR selected galaxies from z=0 to z=0.7 is
consistent with the models built to reproduce the present spiral galaxies.
There is no need to strongly modify of the physical conditions in galaxies to
explain the average evolution of their star formation from z=0 to z=0.7. We use
the models to predict the evolution of the star formation rate and the
metallicity on a wider range of redshift and we compare these predictions with
the results of semi-analytical models.


title: A series whose sum range is an arbitrary finite set

abstract:
  In finitely-dimensional spaces the sum range of a series has to be an affine
subspace. It is long known this is not the case in infinitely dimensional
Banach spaces. In particular in 1984 M.I. Kadets and K. Wo\`{z}niakowski
obtained an example of a series the sum range of which consisted of two points,
and asked whether it is possible to obtain more than two, but finitely many
points. This paper answers the question positively, by showing how to obtain an
arbitrary finite set as the sum range of a series in any infinitely dimensional
Banach space.


title:
The role of translational invariance in non linear gauge theories of
  gravity

abstract:
  The internal structure of the tetrads in a Poincar\'e non linear gauge theory
of gravity is considered. Minkowskian coordinates becomes dynamical degrees of
freedom playing the role of Goldstone bosons of the translations. A critical
length allowing a covariant expansion similar to the weak field approach is
deduced, the zeroth order metric being maximally symmetric (Minkowskian in some
cases).


title: `What is a Thing?': Topos Theory in the Foundations of Physics

abstract:
  The goal of this paper is to summarise the first steps in developing a
fundamentally new way of constructing theories of physics. The motivation comes
from a desire to address certain deep issues that arise when contemplating
quantum theories of space and time. In doing so we provide a new answer to
Heidegger's timeless question ``What is a thing?''.
  Our basic contention is that constructing a theory of physics is equivalent
to finding a representation in a topos of a certain formal language that is
attached to the system. Classical physics uses the topos of sets. Other
theories involve a different topos. For the types of theory discussed in this
paper, a key goal is to represent any physical quantity $A$ with an arrow
$\breve{A}_\phi:\Si_\phi\map\R_\phi$ where $\Si_\phi$ and $\R_\phi$ are two
special objects (the `state-object' and `quantity-value object') in the
appropriate topos, $\tau_\phi$.
  We discuss two different types of language that can be attached to a system,
$S$. The first, $\PL{S}$, is a propositional language; the second, $\L{S}$, is
a higher-order, typed language. Both languages provide deductive systems with
an intuitionistic logic. With the aid of $\PL{S}$ we expand and develop some of
the earlier work (By CJI and collaborators.) on topos theory and quantum
physics. A key step is a process we term `daseinisation' by which a projection
operator is mapped to a sub-object of the spectral presheaf $\Sig$--the topos
quantum analogue of a classical state space. The topos concerned is $\SetH{}$:
the category of contravariant set-valued functors on the category (partially
ordered set) $\V{}$ of commutative sub-algebras of the algebra of bounded
operators on the quantum Hilbert space $\Hi$.


title: Helium line formation and abundance during a C-class flare

abstract:
  During a coordinated campaign which took place in May 2001, a C-class flare
was observed both with SOHO instruments and with the Dunn Solar Telescope of
the National Solar Observatory at Sacramento Peak. In two previous papers we
have described the observations and discussed some dynamical aspects of the
earlier phases of the flare, as well as the helium line formation in the active
region prior to the event. Here we extend the analysis of the helium line
formation to the later phases of the flare in two different locations of the
flaring area. We have devised a new technique, exploiting all available
information from various SOHO instruments, to determine the spectral
distribution of the photoionizing EUV radiation produced by the corona
overlying the two target regions. In order to find semiempirical models
matching all of our observables, we analyzed the effect on the calculated
helium spectrum both of A(He) (the He abundance) and of the uncertainties in
the incident EUV radiation (level and spectral distribution). We found that the
abundance has in most cases (but not in all) a larger effect than the coronal
back-radiation. The result of our analysis is that, considering the error of
the measured lines, and adopting our best estimate for the coronal EUV
illumination, the value A(He)=0.075 +/- 0.010 in the chromosphere (for T>6300
K) and transition region yields reasonably good matches for all the observed
lines. This value is marginally consistent with the most commonly accepted
photospheric value: A(He)=0.085.


title:
XMM-Newton slew survey discovery of the nova XMMSL1 J070542.7-381442
  (V598 Pup)

abstract:
  In an attempt to catch new X-ray transients while they are still bright, the
data taken by XMM-Newton as it slews between targets is being processed and
cross-correlated with other X-ray observations as soon as the slew data appears
in the XMM-Newton archive.
  A bright source, XMMSL1 J070542.7-381442, was detected on 9 Oct 2007 at a
position where no previous X-ray source had been seen. The XMM slew data and
optical data acquired with the Magellan Clay 6.5m telescope were used to
classify the new object.
  No XMM slew X-ray counts are detected above 1keV and the source is seen to be
~750 times brighter than the ROSAT All-Sky Survey upper limit at that position.
The normally m(V)~16 star, USNO-A2.0 0450-03360039, which lies 3.5" from the
X-ray position, was seen in our Magellan data to be very much enhanced in
brightness. Our optical spectrum showed emission lines which identified the
source as a nova in the auroral phase. Hence this optical source is undoubtedly
the progenitor of the X-ray source - a new nova (now also known as V598 Pup).
The X-ray spectrum indicates that the nova was in a super-soft state (with
kT(eff)~35eV). We estimate the distance to the nova to be ~3kpc. Analysis of
archival robotic optical survey data shows a rapid decline light curve
consistent with that expected for a very fast nova.
  The XMM-Newton slew data present a powerful opportunity to find new X-ray
transient objects while they are still bright. Here we present the first such
source discovered by the analysis of near real-time slew data.


title: A Conjecture about the Density of Prime Numbers

abstract:
  We present in this work a heuristic expression for the density of prime
numbers. Our expression leads to results which possesses approximately the same
precision of the Riemann's function in the domain that goes from 2 to 1010 at
least. Instead of using a constant as was done by Legendre and others in the
formula of Gauss, we try to adjust the data through a function. This function
has the remarkable property: its points of discontinuity are the prime numbers.


title: Combinatorial Koszul Homology: Computations and Applications

abstract:
  With a particular focus on explicit computations and applications of the
Koszul homology and Betti numbers of monomial ideals, the main goals of this
thesis are the following:
  Analyze the Koszul homology of monomial ideals and apply it to describe the
structure of monomial ideals. Describe algorithms to perform efficient
computations of the homological invariants of monomial ideals. Apply the theory
and computations on monomial ideals to problems inside and outside mathematics
  The thesis introduces as a main tool Mayer-Vietoris trees of monomial ideals.


title:
Nonequilibrium Quantum Breakdown in a Strongly Correlated Electron
  System

abstract:
  The nonlinear transport properties of the Mott insulator are discussed with
focus on the many-body Landau-Zener mechanism. After reviewing basic concepts
such as the non-adiabatic geometric phase and the Schwinger mechanism, we study
the decay of the insulating groundstate in strong electric fields using the
time-dependent density matrix renormalization group. A short comment on the
proposed mapping to the quantum walk model is added before discussing the
relevance of the theory to experimental results.
  This article is a draft of a book chapter of the book entitled "Quantum and
Semi-classical Percolation & Breakdown" (Lecture Note in Physics,
Springer-Verlag), to appear 2008.


title: On Probing theta_{23} in Neutrino Telescopes

abstract:
  Among all neutrino mixing parameters, the atmospheric neutrino mixing angle
theta_{23} introduces the strongest variation on the flux ratios of ultra high
energy neutrinos. We investigate the potential of these flux ratio measurements
at neutrino telescopes to constrain theta_{23}. We consider astrophysical
neutrinos originating from pion, muon-damped and neutron sources and make a
comparative study of their sensitivity reach to theta_{23}. It is found that
neutron sources are most favorable for testing deviations from maximal
theta_{23}. Using a chi^2 analysis, we show in particular the power of
combining (i) different flux ratios from the same type of source, and also (ii)
combining flux ratios from different astrophysical sources. We include in our
analysis ``impure'' sources, i.e., deviations from the usually assumed initial
(1 : 2 : 0), (0 : 1 : 0) or (1 : 0 : 0) flux compositions.


title: Brane Inflation and Defect Formation

abstract:
  Brane inflation and the production of topological defects at the end of the
inflationary phase are discussed. After a description of the inflationary setup
we discuss the properties of the cosmic strings produced at the end of
inflation. Specific examples of brane inflation are described: $D-\bar D$
inflation, $D3/D7$ inflation and modular inflation


title:
Pair correlation of the zeros of the derivative of the Riemann
  $\xi$-function

abstract:
  The complex zeros of the Riemannn zeta-function are identical to the zeros of
the Riemann xi-function, $\xi(s)$. Thus, if the Riemann Hypothesis is true for
the zeta-function, it is true for $\xi(s)$. Since $\xi(s)$ is entire, the zeros
of $\xi'(s)$, its derivative, would then also satisfy a Riemann Hypothesis. We
investigate the pair correlation function of the zeros of $\xi'(s)$ under the
assumption that the Riemann Hypothesis is true. We then deduce consequences
about the size of gaps between these zeros and the proportion of these zeros
that are simple.


title: The molecular polar disc in NGC 2768

abstract:
  We present CO(1-0) and CO(2-1) maps of the molecular polar disc in the
elliptical galaxy NGC 2768 obtained at the IRAM Plateau de Bure Interferometer.
The maps have a resolution of 2.6" x 2.3" and 1.2" x 1.2" for the CO(1-0) and
CO(2-1) lines, respectively. The CO maps complete the unique picture of the
interstellar medium (ISM) of NGC 2768; the dust, molecular gas, ionised gas and
neutral hydrogen (HI) trace the recent acquisition of cold and cool gas over
two orders of magnitude in radii (and much more in density). In agreement with
the other ISM components, the CO distribution extends nearly perpendicularly to
the photometric major axis of the galaxy. Velocity maps of the CO show a
rotating polar disc or ring in the inner kiloparsec. This cool gas could lead
to kinematic substructure formation within NGC 2768. However, the stellar
velocity field and H-beta absorption linestrength maps from the optical
integral-field spectrograph SAURON give no indication of a young and
dynamically cold stellar population coincident with the molecular polar disc.
Very recent or weak star formation, undetectable in linestrengths, nevertheless
remains a possibility and could be at the origin of some of the ionised gas
observed. Millimetre continuum emission was also detected in NGC 2768, now one
of only a few low-luminosity active galactic nuclei with observed millimetre
continuum emission.


title: Curvature of a class of indefinite globally framed $f$-manifolds

abstract:
  We present a compared analysis of some properties of indefinite almost
$\mathcal{S}$-manifolds and indefinite $\mathcal{S}$-manifolds. We give some
characterizations in terms of the Levi-Civita connection and of the
characteristic vector fields. We study the sectional and ${\phi}$-sectional
curvature of indefinite almost $\mathcal{S}$-manifolds and state an expression
of the curvature tensor field for the indefinite $\mathcal{S}$-space forms. We
analyse the sectional curvature of indefinite $\mathcal{S}$-manifold in which
the number of the spacelike characteristic vector fields is equal to that of
the timelike characteristic vector fields. Some examples are also described.


title:
Zero-Forcing Precoding for Frequency Selective MIMO Channels with
  $H^\infty$ Criterion and Causality Constraint

abstract:
  We consider zero-forcing equalization of frequency selective MIMO channels by
causal and linear time-invariant precoders in the presence of intersymbol
interference. Our motivation is twofold. First, we are concerned with the
optimal performance of causal precoders from a worst case point of view.
Therefore we construct an optimal causal precoder, whereas contrary to other
works our construction is not limited to finite or rational impulse responses.
Moreover we derive a novel numerical approach to computation of the optimal
perfomance index achievable by causal precoders for given channels. This
quantity is important in the numerical determination of optimal precoders.


title:
LaFeAsO$_{1-x}$F$_x$: A low carrier density superconductor near
  itinerant magnetism

abstract:
  Density functional studies of 26K superconducting LaFeAs(O,F) are reported.
We find a low carrier density, high density of states, $N(E_F)$ and modest
phonon frequencies relative to $T_c$. The high $N(E_F)$ leads to proximity to
itinerant magnetism, with competing ferromagnetic and antiferromagnetic
fluctuations and the balance between these controlled by doping level. Thus
LaFeAs(O,F) is in a unique class of high $T_c$ superconductors: high $N(E_F)$
ionic metals near magnetism.


title:
Distribution of carrier multiplication rates in CdSe and InAs
  nanocrystals

abstract:
  The distribution of rates of carrier multiplication (CM) following photon
absorption is calculated for semiconductor nanocrystals (NCs). The NC
electronic structure is described using a screened pseudopotential method known
to give reliable description of NC excitons. The rates of biexciton generation
are calculated using the Fermi golden rule with all relevant Coulomb matrix
elements, taking into account proper selection rules. In CdSe and InAs NCs we
find a broad distribution biexciton generation rates depending strongly on the
exciton energy and size of the NC. The process becomes inefficient for NC
exceeding 3 nm in diameter in the photon energy range of 2-3 times the band
gap.


title:
Scale-free vortex cascade emerging from random forcing in a strongly
  coupled system

abstract:
  The notions of self-organised criticality (SOC) and turbulence are
traditionally considered to be applicable to disjoint classes of phenomena.
Nevertheless, scale-free burst statistics is a feature shared by turbulent as
well as self-organised critical dynamics. It has also been suggested that
another shared feature is universal non-gaussian probability density functions
(PDFs) of global fluctuations. Here, we elucidate the unifying aspects through
analysis of data from a laboratory dusty plasma monolayer. We compare analysis
of experimental data with simulations of a two-dimensional (2D) many-body
system, of 2D fluid turbulence, and a 2D SOC model, all subject to random
forcing at small scales. The scale-free vortex cascade is apparent from
structure functions as well as spatio-temporal avalanche analysis, the latter
giving similar results for the experimental and all model systems studied. The
experiment exhibits global fluctuation statistics consistent with a
non-gaussian universal PDF, but the model systems yield this result only in a
restricted range of forcing conditions.


title:
Dressed excitonic states and quantum interference in a three-level
  quantum dot ladder system

abstract:
  We observe dressed states and quantum interference effects in a strongly
driven three-level quantum dot ladder system. The effect of a strong coupling
field on one dipole transition is measured by a weak probe field on the second
dipole transition using differential reflection. When the coupling energy is
much larger than both the homoge-neous and inhomogeneous linewidths an
Autler-Townes splitting is observed. Striking differences are observed when the
transitions resonant with the strong and weak fields are swapped, particularly
when the coupling energy is nearly equal to the measured linewidth. This result
is attributed to quantum interference: a modest destructive or constructive
interference is observed depending on the pump / probe geometry. The data
demonstrate that coher-ence of both the bi-exciton and the exciton is
maintained in this solid-state system, even under intense illumina-tion, which
is crucial for prospects in quantum information processing and non-linear
optical devices.


title: The square negative correlation property for generalized Orlicz balls

abstract:
  Antilla, Ball and Perissinaki proved that the squares of coordinate functions
in $\ell_p^n$ are negatively correlated. This paper extends their results to
balls in generalized Orlicz norms on R^n. From this, the concentration of the
Euclidean norm and a form of the Central Limit Theorem for the generalized
Orlicz balls is deduced. Also, a counterexample for the square negative
correlation hypothesis for 1-symmetric bodies is given.
  Currently the CLT is known in full generality for convex bodies (see the
paper "Power-law estimates for the central limit theorem for convex sets" by B.
Klartag), while for generalized Orlicz balls a much more general result is true
(see "The negative association property for the absolute values of random
variables equidistributed on a generalized Orlicz ball" by M. Pilipczuk and J.
O. Wojtaszczyk). While, however, both aforementioned papers are rather long,
complicated and technical, this paper gives a simple and elementary proof of,
eg., the Euclidean concentration for generalized Orlicz balls.


title:
The negative association property for the absolute values of random
  variables equidistributed on a generalized Orlicz ball

abstract:
  Random variables equidistributed on convex bodies have received quite a lot
of attention in the last few years. In this paper we prove the negative
association property (which generalizes the subindependence of coordinate
slabs) for generalized Orlicz balls. This allows us to give a strong
concentration property, along with a few moment comparison inequalities. Also,
the theory of negatively associated variables is being developed in its own
right, which allows us to hope more results will be available. Moreover, a
simpler proof of a more general result for $\ell_p^n$ balls is given.


title: Fermion Tunneling from Dynamical Horizons

abstract:
  The instability against emission of fermionic particles by the trapping
horizon of an evolving black hole is analyzed using the Hamilton-Jacobi
tunneling method. This method automatically selects one special expression for
the surface gravity of a changing horizon. The results also apply to point
masses embedded in an expanding universe. As a bonus of the tunneling method,
we gain the insight that the surface gravity still defines a temperature
parameter as long as the evolution is sufficiently slow that the black hole
pass through a sequence of quasi-equilibrium states, and that black holes
should be semi-classically unstable even in a hypothetical world without
bosonic fields.


title: Double Power Law Decay of the Persistence in Financial Markets

abstract:
  The persistence phenomenon is studied in the Japanese financial market by
using a novel mapping of the time evolution of the values of shares quoted on
the Nikkei Index onto Ising spins. The method is applied to historical end of
day data from the Japanese stock market during 2002. By studying the time
dependence of the spins, we find clear evidence for a double-power law decay of
the proportion of shares that remain either above or below ` starting\rq\
values chosen at random. The results are consistent with a recent analysis of
the data from the London FTSE100 market. The slopes of the power-laws are also
in agreement. We estimate a long time persistence exponent for the underlying
Japanese financial market to be 0.5.


title: On finiteness of odd superperfect numbers

abstract:
  Some new results concerning the equation $\sigma(N)=aM, \sigma(M)=bN$ are
proved. As a corollary, there are only finitely many odd superperfect numbers
with a fixed number of distinct prime factors.


title: On population extinction risk in the aftermath of a catastrophic event

abstract:
  We investigate how a catastrophic event (modeled as a temporary fall of the
reproduction rate) increases the extinction probability of an isolated
self-regulated stochastic population. Using a variant of the Verhulst logistic
model as an example, we combine the probability generating function technique
with an eikonal approximation to evaluate the exponentially large increase in
the extinction probability caused by the catastrophe. This quantity is given by
the eikonal action computed over "the optimal path" (instanton) of an effective
classical Hamiltonian system with a time-dependent Hamiltonian. For a general
catastrophe the eikonal equations can be solved numerically. For simple models
of catastrophic events analytic solutions can be obtained. One such solution
becomes quite simple close to the bifurcation point of the Verhulst model. The
eikonal results for the increase in the extinction probability caused by a
catastrophe agree well with numerical solutions of the master equation.


title: Optimizing polynomials for floating-point implementation

abstract:
  The floating-point implementation of a function on an interval often reduces
to polynomial approximation, the polynomial being typically provided by Remez
algorithm. However, the floating-point evaluation of a Remez polynomial
sometimes leads to catastrophic cancellations. This happens when some of the
polynomial coefficients are very small in magnitude with respects to others. In
this case, it is better to force these coefficients to zero, which also reduces
the operation count. This technique, classically used for odd or even
functions, may be generalized to a much larger class of functions. An algorithm
is presented that forces to zero the smaller coefficients of the initial
polynomial thanks to a modified Remez algorithm targeting an incomplete
monomial basis. One advantage of this technique is that it is purely numerical,
the function being used as a numerical black box. This algorithm is implemented
within a larger polynomial implementation tool that is demonstrated on a range
of examples, resulting in polynomials with less coefficients than those
obtained the usual way.


title:
Ab-initio description of hole localization and Zhang-Rice singlets in
  one-dimensional doped cuprates

abstract:
  We present the first ab-initio band-theory-based description of
spin-compensated polarons (known as Zhang-Rice singlets) in a hole-doped
cuprate, specifically one-dimensional Ca_{2+x} Y_{2-x} Cu_5 O_10. Zhang-Rice
singlets are many-particle configurations relevant to the exotic behavior of
hole-doped cuprates, stemming from spontaneous charge localization. They appear
in our case-study material above a threshold doping, successively turning the
insulating undoped antiferromagnet into a gap insulator, a singlet-rich
metallic paramagnet, and finally, a singlet-saturated insulating diamagnet.


title: Multivariate integration in C^\infty([0,1]^d) is not strongly tractable

abstract:
  It has long been known that the multivariate integration problem for the unit
ball in $C^r([0,1]^d)$ is intractable for fixed finite $r$. H. Wo\'zniakowski
has recently conjectured that this is true even if $r=\infty$. This paper
establishes a partial result in this direction. We prove that the multivariate
integration problem, for infinitely differential functions all of whose
variables are bounded by one, is not strongly tractable.


title: Individual Risk and Lebesgue Extension without Aggregate Uncertainty

abstract:
  Many economic models include random shocks imposed on a large number
(continuum) of economic agents with individual risk. In this context, an exact
law of large numbers and its converse is presented in Sun (2006) to
characterize the cancelation of individual risk via aggregation. However, it is
well known that the Lebesgue unit interval is not suitable for modeling a
continuum of agents in the particular setting. The purpose of this paper is to
show that an extension of the Lebesgue unit interval does work well as an agent
space with various desirable properties associated with individual risk.


title:
Vertex degrees of Steiner Minimal Trees in $\ell_p^d$ and other smooth
  Minkowski spaces

abstract:
  We find upper bounds for the degrees of vertices and Steiner points in
Steiner Minimal Trees in the d-dimensional Banach spaces \ell_p^d independent
of d. This is in contrast to Minimal Spanning Trees, where the maximum degree
of vertices grows exponentially in d (Robins and Salowe, 1995). Our upper
bounds follow from characterizations of singularities of SMT's due to Lawlor
and Morgan (1994), which we extend, and certain \ell_p-inequalities. We derive
a general upper bound of d+1 for the degree of vertices of an SMT in an
arbitrary smooth d-dimensional Banach space; the same upper bound for Steiner
points having been found by Lawlor and Morgan. We obtain a second upper bound
for the degrees of vertices in terms of 1-summing norms.


title:
Multicritical Nishimori point in the phase diagram of the +- J Ising
  model on a square lattice

abstract:
  We investigate the critical behavior of the random-bond +- J Ising model on a
square lattice at the multicritical Nishimori point in the T-p phase diagram,
where T is the temperature and p is the disorder parameter (p=1 corresponds to
the pure Ising model). We perform a finite-size scaling analysis of
high-statistics Monte Carlo simulations along the Nishimori line defined by
$2p-1={\rm Tanh}(1/T)$, along which the multicritical point lies. The
multicritical Nishimori point is located at p^*=0.89081(7), T^*=0.9528(4), and
the renormalization-group dimensions of the operators that control the
multicritical behavior are y_1=0.655(15) and y_2 = 0.250(2); they correspond to
the thermal exponent \nu= 1/y_2=4.00(3) and to the crossover exponent \phi=
y_1/y_2=2.62(6).


title:
Lattice-mismatch-induced granularity in CoPt-NbN and NbN-CoPt
  superconductor-ferromagnet heterostructures: Effect of strain

abstract:
  The effect of strain due to lattice mismatch and of ferromagnetic (FM)
exchange field on superconductivity (SC) in NbN-CoPt bilayers is investigated.
Two different bilayer systems with reversed deposition sequence are grown on
MgO (001) single crystals. While robust superconductivity with high critical
temperature (T_c ~ 15.3 K) and narrow transition width DelT_c ~ 0.4 K) is seen
in two types of CoPt-NbN/MgO heterostructures where the magnetic anisotropy of
CoPt is in-plane in one case and out-of-plane in the other, the NbN-CoPt/MgO
system shows markedly suppressed SC response. The reduced SC order parameter of
this system, which manifests itself in Tc, temperature dependence of critical
current density J_c (T), and angular (Phi) variation of flux-flow resistivity
Rho_f is shown to be a signature of the structure of NbN film and not a result
of the exchange field of CoPt. The Rho_f (H,T,Phi) data further suggest that
the domain walls in the CoPt film are of the Neel type and hence do not cause
any flux in the superconducting layer. A small, but distinct increase in the
low-field critical current of the CoPt-NbN couple is seen when the magnetic
layer has perpendicular anisotropy.


title:
On the High Energy Behaviour of The Total Cross Section in the QCD
  Dipole Model

abstract:
  In this paper we perform a numerical study of the tranverse expansion of
hadronic scattering amplitudes in the dipole picture of high energy QCD. We go
beyond the mean field approximation by including fluctuations and also wave
function saturation effects, and the evolution with both a fixed and a running
coupling is investigated. We also study the nonperturbative aspects, and as has
been predicted earlier, our results indicate that the Froissart-Martin bound is
saturated once confinement effects are included in the evolution. Thus the
total cross section increases proportional to the square of the logarithm of
the cms energy. Furthermore it is seen that we obtain a reasonable value for
the proportionality coefficient. The impact of saturation and non-leading
effects on this coefficient is also studied.


title: Duality for toric Landau-Ginzburg models

abstract:
  We introduce a duality construction for toric Landau-Ginzburg models,
applicable to complete intersections in toric varieties via the sigma model /
Landau-Ginzburg model correspondence. This construction is shown to reconstruct
those of Batyrev-Borisov, Berglund-H"ubsch, Givental, and Hori-Vafa. It can be
done in more general situations, and provides partial resolutions when the
above constructions give a singular mirror. An extended example is given: the
Landau-Ginzburg models dual to elliptic curves in (P^1)^2 .


title: Hen 2-104: A close-up look at the Southern Crab

abstract:
  The kinematics, shaping, density distribution, expansion distance, and
ionized mass of the nebula Hen 2-104, and the nature of its symbiotic Mira are
investigated. A combination of multi-epoch HST images and VLT integral field
high-resolution spectroscopy is used to study the nebular dynamics both along
the line of sight and in the plane of the sky. These observations allow us to
construct a 3-D spatio-kinematical model of the nebula, which together with the
measurement of its apparent expansion in the plane of the sky over a period of
4 years, provides the expansion parallax for the nebula. The integral field
data featuring the [S{\sc ii}] $\lambda\lambda$671.7,673.1 emission line
doublet provide us with a density map of the inner lobes of the nebula, which
together with the distance estimation allow us to estimate its ionized mass. We
find densities ranging from n$_e$=500 to 1000 cm$^{-3}$ in the inner lobes and
from 300 to 500cm$^{-3}$ in the outer lobes. We determine an expansion parallax
distance of 3.3$\pm$0.9 kpc to Hen 2-104, implying an unexpectedly large
ionized mass for the nebula of the order of one tenth of a solar mass.


title: Two Be stars in the Small Magellanic Cloud with B[e]-like properties

abstract:
  We present an analysis of UVES and MIKE (ground based) high resolution and
Far Ultraviolet Spectroscopic Explorer spectra of two novel and photometrically
variable bright blue stars in the SMC; OGLE004336.91-732637.7 and the
periodically occulted star OGLE004633.76-731204.3. The light curves of these
stars exhibit multiple frequencies, and their spectra are similar. The latter
are dominated by absorption/emission features produced in a circumstellar (CS)
envelope whereas photospheric features are barely visible and forbidden
emission lines are not visible. Modeling of spectral features indicates similar
physical conditions for the CS envelope in both stars. An optically thick,
slowly and thermally stratified disk. OGLE004633.76-731204.3 is noteworthy in
showing blue discrete absorption components ("BACs") in their spectra possibly
indicating the shock interaction between high velocity and low velocity
material. Optical spectra from two spectra separated by 5 years show little
change in the radial velocity over this period. However because these
observations happen to be made in roughly similar phases over their long
period, these suggest only that the stars are not in close binaries. We
interpret the occultations and additional photometric nearly periodic
variability in OGLE004633.76-731204.3 as due to covering of the star by a
density modulation in a sector of a quasi-Keplerian circumstellar disk.
Altogether, we suggest that these stars are prototypes of a larger group of
stars, which we dub the "bgBe's" and discuss their similarities and differences
with respect to the well known sgB[e] variables. Although
OGLE004336.91-732637.7 appears to be a member the open cluster NGC 242, the
evolutionary context of these stars is unclear.


title:
Inferring Neuronal Network Connectivity from Spike Data: A Temporal
  Datamining Approach

abstract:
  Understanding the functioning of a neural system in terms of its underlying
circuitry is an important problem in neuroscience. Recent developments in
electrophysiology and imaging allow one to simultaneously record activities of
hundreds of neurons. Inferring the underlying neuronal connectivity patterns
from such multi-neuronal spike train data streams is a challenging statistical
and computational problem. This task involves finding significant temporal
patterns from vast amounts of symbolic time series data. In this paper we show
that the frequent episode mining methods from the field of temporal data mining
can be very useful in this context. In the frequent episode discovery
framework, the data is viewed as a sequence of events, each of which is
characterized by an event type and its time of occurrence and episodes are
certain types of temporal patterns in such data. Here we show that, using the
set of discovered frequent episodes from multi-neuronal data, one can infer
different types of connectivity patterns in the neural system that generated
it. For this purpose, we introduce the notion of mining for frequent episodes
under certain temporal constraints; the structure of these temporal constraints
is motivated by the application. We present algorithms for discovering serial
and parallel episodes under these temporal constraints. Through extensive
simulation studies we demonstrate that these methods are useful for unearthing
patterns of neuronal network connectivity.


title: On the characterization of Hilbertian fields

abstract:
  The main goal of this work is to answer a question of P. D`ebes and D. Haran
by relaxing the condition for Hilbertianity. Namely we prove that for a field K
to be Hilbertian it suffices that K has the irreducible specialization property
merely for absolutely irreducible polynomials.


title:
The decreasing property of relative entropy and the strong
  superadditivity of quantum channels

abstract:
  We argue that a fundamental (conjectured) property of memoryless quantum
channels, namely the strong superadditivity, is intimately related to the
decreasing property of the quantum relative entropy. Using the latter we first
give, for a wide class of input states, an estimation of the output entropy for
phase damping channels and some Weyl quantum channels. Then we prove, without
any input restriction, the strong superadditivity for several quantum channels,
including depolarizing quantum channels, quantum-classical channels and quantum
erasure channels.


title: Suppression of the Shear Viscosity in a "semi" Quark Gluon Plasma

abstract:
  We consider QCD at temperatures T near Tc, where the theory deconfines. We
distinguish between a "complete" Quark Gluon Plasma (QGP), where the vacuum
expectation value of the renormalized Polyakov loop is near unity, essentially
constant with T, and the "semi"-QGP, where the loop changes strongly with T.
Lattice simulations indicate that in QCD, there is a semi-QGP from below Tc to
a few times that. Using a semi-classical model, we compute the shear viscosity,
eta, to leading order in perturbation theory. We find that near Tc, where the
expectation value of the Polyakov loop is small, that eta/T^3 is suppressed by
two powers of the loop. For heavy ions, this suggests that during the initial
stages of the collision, hydrodynamic behavior at the LHC will be characterized
by a shear viscosity which is significantly larger than that at RHIC.


title:
Inhomogeneous vortex-state-driven enhancement of superconductivity in
  nanoengineered ferromagnet-superconductor heterostructures

abstract:
  Thin film heterostructures provide a powerful means to study the antagonism
between superconductivity (SC) and ferromagnetism (FM). One interesting issue
in FM-SC hybrids which defies the notion of antagonistic orders is the
observation of magnetic field induced superconductivity (FIS). Here we show
that in systems where the FM domains/islands produce spatial inhomogeneities of
the SC order parameter, the FIS can derive significant contribution from
different mobilities of the magnetic flux identified by two distinct critical
states in the inhomogeneous superconductor. Our experiments on nanoengineered
bilayers of ferromagnetic CoPt and superconducting NbN where CoPt/NbN islands
are separated by a granular NbN, lend support to this alternative explanation
of FIS in certain class of FM-SC hybrids.


title: Stability of BTZ black strings

abstract:
  We study the dynamical stability of the BTZ black string against fermonic and
gravitational perturbations. The BTZ black string is not always stable against
these perturbations. There exist threshold values for $m^2$ related to the
compactification of the extra dimension for fermonic perturbation, scalar part
of the gravitational perturbation and the tensor perturbation, respectively.
Above the threshold values, perturbations are stable; while below these
thresholds, perturbations can be unstable. We find that this non-trivial
stability behavior qualitatively agrees with that predicted by a
thermodynamical argument, showing that the BTZ black string phase is not the
privileged stable phase.


title:
On the Spectrum of an Operator Pencil with Applications to Wave
  Propagation in Periodic and Frequency Dependent Materials

abstract:
  We study wave propagation in periodic and frequency dependent materials. The
approach in this paper leads to spectral analysis of a quadratic operator
pencil where the spectral parameter relates to the quasimomentum and the
frequency is a parameter. We show that the underlying operator has a discrete
spectrum, where the eigenvalues are symmetrically placed with respect to the
real and imaginary axis. Moreover, we discretize the operator pencil with
finite elements and use a Krylov space method to compute eigenvalues of the
resulting large sparse matrix pencil.


title: Hard QCD at hadron colliders

abstract:
  We review the status of QCD at hadron colliders with emphasis on precision
predictions and the latest theoretical developments for cross sections
calculations to higher orders. We include an overview of our current
information on parton distributions and discuss various Standard Model
reactions such as W/Z-boson, Higgs boson or top quark production.


title:
Stein's method and exact Berry--Esseen asymptotics for functionals of
  Gaussian fields

abstract:
  We show how to detect optimal Berry--Esseen bounds in the normal
approximation of functionals of Gaussian fields. Our techniques are based on a
combination of Malliavin calculus, Stein's method and the method of moments and
cumulants, and provide de facto local (one-term) Edgeworth expansions. The
findings of the present paper represent a further refinement of the main
results proven in Nourdin and Peccati [Probab. Theory Related Fields 145 (2009)
75--118]. Among several examples, we discuss three crucial applications: (i) to
Toeplitz quadratic functionals of continuous-time stationary processes
(extending results by Ginovyan [Probab. Theory Related Fields 100 (1994)
395--406] and Ginovyan and Sahakyan [Probab. Theory Related Fields 138 (2007)
551--579]); (ii) to ``exploding'' quadratic functionals of a Brownian sheet;
and (iii) to a continuous-time version of the Breuer--Major CLT for functionals
of a fractional Brownian motion.


title: Entropy of polydisperse chains: solution on the Bethe lattice

abstract:
  We consider the entropy of polydisperse chains placed on a lattice. In
particular, we study a model for equilibrium polymerization, where the
polydispersivity is determined by two activities, for internal and endpoint
monomers of a chain. We solve the problem exactly on a Bethe lattice with
arbitrary coordination number, obtaining an expression for the entropy as a
function of the density of monomers and mean molecular weight of the chains. We
compare this entropy with the one for the monodisperse case, and find that the
excess of entropy due to polydispersivity is identical to the one obtained for
the one-dimensional case. Finally, we obtain an exponential distribution of
molecular weights.


title: Balancing unit vectors

abstract:
  Theorem A. Let $x_1,...,x_{2k+1}$ be unit vectors in a normed plane. Then
there exist signs $\epsi_1,...,\epsi_{2k+1}\in\{\pm 1\}$ such that
$\norm{\sum_{i=1}^{2k+1}\epsi_i x_i}\leq 1$.
  We use the method of proof of the above theorem to show the following point
facility location result, generalizing Proposition 6.4 of Y. S. Kupitz and H.
Martini (1997).
  Theorem B. Let $p_0,p_1,...,p_n$ be distinct points in a normed plane such
that for any $1\leq i<j\leq n$ the closed angle $\angle p_ip_0p_j$ contains a
ray opposite some $\overrightarrow{p_0p_k}, 1\leq k\leq n$. Then $p_0$ is a
Fermat-Toricelli point of $\{p_0,p_1,...,p_n\}$, i.e. $x=p_0$ minimizes
$\sum_{i=0}^n\norm{x-p_i}$.
  We also prove the following dynamic version of Theorem A.
  Theorem C. Let $x_1,x_2,...$ be a sequence of unit vectors in a normed plane.
Then there exist signs $\epsi_1,\epsi_2,...\in\{\pm 1\}$ such that
$\norm{\sum_{i=1}^{2k}\epsi_i x_i}\leq 2$ for all $k\in\N$.
  Finally we discuss a variation of a two-player balancing game of J. Spencer
(1977) related to Theorem C.


title: The finiteness dimension of local cohomology modules and its dual notion

abstract:
  Let \fa be an ideal of a commutative Noetherian ring R and M a finitely
generated R-module. We explore the behavior of the two notions f_{\fa}(M), the
finiteness dimension of M with respect to \fa, and, its dual notion q_{\fa}(M),
the Artinianess dimension of M with respect to \fa. When (R,\fm) is local and
r:=f_{\fa}(M) is less than f_{\fa}^{\fm}(M), the \fm-finiteness dimension of M
relative to \fa, we prove that H^r_{\fa}(M) is not Artinian, and so the filter
depth of \fa on M doesn't exceeds f_{\fa}(M). Also, we show that if M has
finite dimension and H^i_{\fa}(M) is Artinian for all i>t, where t is a given
positive integer, then H^t_{\fa}(M)/\fa H^t_{\fa}(M) is Artinian. It
immediately implies that if q:=q_{\fa}(M)>0, then H^q_{\fa}(M) is not finitely
generated, and so f_{\fa}(M)\leq q_{\fa}(M).


title: Precision Studies of the NNLO DGLAP Evolution at the LHC with CANDIA

abstract:
  We summarize the theoretical approach to the solution of the NNLO DGLAP
equations using methods based on the logarithmic expansions in x-space and
their implementation into the C program Candia 1.0. We present the various
options implemented in the program and discuss the different solutions. The
user can choose the order of the evolution, the type of the solution, which can
be either exact or truncated, and the evolution either with a fixed or a
varying flavor number, implemented in the varying-flavour-number scheme (VFNS).
The renormalization and factorization scale dependences are treated separately.
In the non-singlet sector the program implements an exact NNLO solution.


title: Semigroup cohomology and applications

abstract:
  This article is a survey of the author's research. It consists of three
sections concerned three kinds of cohomologies of semigroups. Section 1
considers `classic' cohomology as it was introduced by Eilenberg and MacLane.
Here the attention is concentrated mainly on semigroups having cohomological
dimension 1. In Section 2 a generalization of the Eilenberg-MacLane cohomology
is introduced, the so-called 0-cohomology, which appears in applied topics
(projective representations of semigroups, Brauer monoids). At last Section 3
is devoted to further generalizing: partial cohomology defined and discussed in
it are used then for calculation of the classic cohomology for some semigroups.


title:
The stellar population histories of early-type galaxies. III. The Coma
  Cluster

abstract:
  We present stellar population parameters of twelve early-type galaxies (ETGs)
in the Coma Cluster based on spectra obtained using the Low Resolution Imaging
Spectrograph on the Keck II Telescope. Our data allow us to examine in detail
the zero-point and scatter in their stellar population properties. Our ETGs
have SSP-equivalent ages of on average 5-8 Gyr with the models used here, with
the oldest galaxies having ages of ~10 Gyr old. This average age is identical
to the mean age of field ETGs. Our ETGs span a large range in velocity
dispersion but are consistent with being drawn from a population with a single
age. Specifically, ten of the twelve ETGs are consistent within their formal
errors of having the same age, 5.2+/-0.2 Gyr, over a factor of more than 750 in
mass. We therefore find no evidence for downsizing of the stellar populations
of ETGs in the core of the Coma Cluster. We suggest that Coma Cluster ETGs may
have formed the majority of their mass at high redshifts but suffered small but
detectable star formation events at z~0.1-0.3. Previous detections of
'downsizing' from stellar populations of local ETGs may not reflect the same
downsizing seen in lookback studies of RSGs, as the young ages of the local
ETGs represent only a small fraction of their total masses. (abridged)


title: Data compression and genomes: a two dimensional life domain map

abstract:
  We define the complexity of DNA sequences as the information content per
nucleotide, calculated by means of some Lempel-Ziv data compression algorithm.
It is possible to use the statistics of the complexity values of the functional
regions of different complete genomes to distinguish among genomes of different
domains of life (Archaea, Bacteria and Eukarya). We shall focus on the
distribution function of the complexity of noncoding regions. We show that the
three domains may be plotted in separate regions within the two-dimensional
space where the axes are the skewness coefficient and the curtosis coefficient
of the aforementioned distribution. Preliminary results on 15 genomes are
introduced.


title:
The Luminosities and Distance Scales of Type II Cepheid and RR Lyrae
  variables

abstract:
  Infrared and optical absolute magnitudes are derived for the type II Cepheids
kappa Pav and VY Pyx from revised Hipparcos parallaxes and for kappa Pav, V553
Cen and SW Tau from pulsation parallaxes. Phase-corrected JHK mags are given
for 142 RR Lyrae variables based on 2MASS data. RR Lyrae itself is overluminous
compared with LMC RR Lyraes at the classical Cepheid modulus (18.39) consistent
with a prediction of Catalan and Cortes. V553 Cen and SW Tau deviate by only
0.02 mag in the mean from the Matsunaga PL(K) relation for globular cluster
type II Cepheids with a zero-point based on the same LMC modulus. Comparing
directly these two stars with type II Cepheids in the LMC and in the Galactic
Bulge leads to an LMC modulus of 18.37\pm0.09 and a distance to the Galactic
Centre of 7.64\pm 0.21kpc. Kappa Pav may be a binary. V553 Cen and SW Tau show
that at optical wavelengths PL relations are wider for field stars than for
those in globular clusters (abridged).


title:
A spatial envelope soliton model of the electron - propagating within a
  fictitious waveguide

abstract:
  The paper proposes an envelope soliton model of the electron. The soliton
propagates within a waveguide which size varies with the potential. The soliton
is the solution of the Schroedinger equation with the addition of a nonlinear
term that is the negative of Bohm's Quantum potential. This potential is
interpreted as representing the dispersion of the linear equation. The model is
based on de Broglie's original wave-particle concept, which is based on the
Special theory of relativity. The model thus illustrates that theory.


title:
MOND and the lensing Fundamental Plane: No need for dark matter on
  galaxy scales

abstract:
  Bolton et al. (2007) have derived a mass-based fundamental plane using
photometric and spectroscopic observations of 36 strong gravitational lenses.
The lensing allows a direct determination of the mass-surface density and so
avoids the usual dependence on mass-to-light ratio. We consider this same
sample in the context of modified Newtonian dynamics (MOND) and demonstrate
that the observed mass-based fundamental plane coincides with the MOND
fundamental plane determined previously for a set of high-order polytropic
spheres chosen to match the observed range of effective radii and velocity
dispersions in elliptical galaxies. Moreover, the observed projected mass
within one-half an effective radius is consistent with the mass in visible
stars plus a small additional component of ``phantom dark matter'' resulting
from the MOND contribution to photon deflection.


title:
Correlations between morphology, crystal structure and magnetization of
  epitaxial cobalt-platinum films grown with pulsed laser ablation

abstract:
  The effects of growth rate (G_r), deposition temperature (T_d), film
thickness (t_F), and substrate induced strain (epsilon) on morphological,
crystallographic and magnetic characteristics of equiatomic CoPt epitaxial
films synthesized with PLD are investigated. The (001) substrates of MgO, STO
and LAO provide different degree of epitaxial strain for growth of the
disordered face centered cubic (fcc) and ordered face centered tetragonal
(L1_0) phases of CoPt. The films deposited at T_d~600 ^0C on all three
substrates are fcc with in-plane magnetization and a narrow hysteresis loop of
width~200 Oe. The L1_0 phase, stabilized only at T_d~700 ^0C becomes
predominantly c-axis oriented as T_d is increased to 800 ^0C. While the
crystallographic structure of the films depends solely on the T_d, their
microstructure and magnetization characteristics are decided by the growth
rate. At the higher G_r (~1A/sec) the L1_0 films have a maze-like structure
which converts to a continuous film as the t_F is increased from 20 to 50 nm.
The H_c of these films increases as the L1_0 phase fraction grows with T_d and
its orientation becomes out of the film plane. The evolution of microstructure
with T_d is remarkably different at lower growth rate (~0.4A /sec). Here the
structure changes from a self-similar fractal pattern to an assembly of
nano-dots as the T_d is raised from 700 to 800 ^0C, and is understood in terms
of the imbalance between strain and interfacial energies. MFM of such films
reveals no distinct domain walls within the nano-islands while a clear contrast
is seen between the islands of reversed magnetization. The simple picture of
coherent rotation of moment appears incompatible with the time dependence of
the remanent magnetization in these films.


title:
Feedback cooling of the normal modes of a massive electromechanical
  system to submillikelvin temperature

abstract:
  We apply a feedback cooling technique to simultaneously cool the three
electromechanical normal modes of the ton-scale resonant-bar gravitational wave
detector AURIGA. The measuring system is based on a dc Superconducting Quantum
Interference Device (SQUID) amplifier, and the feedback cooling is applied
electronically to the input circuit of the SQUID. Starting from a bath
temperature of 4.2 K, we achieve a minimum temperature of 0.17 mK for the
coolest normal mode. The same technique, implemented in a dedicated experiment
at subkelvin bath temperature and with a quantum limited SQUID, could allow to
approach the quantum ground state of a kilogram-scale mechanical resonator.


title: Using the smoothness of p-1 for computing roots modulo p

abstract:
  We prove, without recourse to the Extended Riemann Hypothesis, that the
projection modulo $p$ of any prefixed polynomial with integer coefficients can
be completely factored in deterministic polynomial time if $p-1$ has a $(\ln
p)^{O(1)}$-smooth divisor exceeding $(p-1)^{{1/2}+\delta}$ for some arbitrary
small $\delta$. We also address the issue of computing roots modulo $p$ in
deterministic time.


title: On decomposition of commutative Moufang groupoids

abstract:
  We prove that every commutative Moufang groupoid is a semilattice of
Archimedean subgroupoids.


title: Stream sampling for variance-optimal estimation of subset sums

abstract:
  From a high volume stream of weighted items, we want to maintain a generic
sample of a certain limited size $k$ that we can later use to estimate the
total weight of arbitrary subsets. This is the classic context of on-line
reservoir sampling, thinking of the generic sample as a reservoir. We present
an efficient reservoir sampling scheme, $\varoptk$, that dominates all previous
schemes in terms of estimation quality.
  $\varoptk$ provides {\em variance optimal unbiased estimation of subset
sums}. More precisely, if we have seen $n$ items of the stream, then for {\em
any} subset size $m$, our scheme based on $k$ samples minimizes the average
variance over all subsets of size $m$. In fact, the optimality is against any
off-line scheme with $k$ samples tailored for the concrete set of items seen.
In addition to optimal average variance, our scheme provides tighter worst-case
bounds on the variance of {\em particular} subsets than previously possible. It
is efficient, handling each new item of the stream in $O(\log k)$ time.
Finally, it is particularly well suited for combination of samples from
different streams in a distributed setting.


title:
Magnetohydrodynamic Model of Equatorial Plasma Torus in Planetary
  Nebulae

abstract:
  Some basic structures in planetary nebulae are modeled as self-organized
magnetohydrodynamic (MHD) plasma configurations with radial flow. These
configurations are described by time self-similar dynamics, where space and
time dependences of each physical variable are in separable form. Axisymmetric
toroidal MHD plasma configuration is solved under the gravitational field of a
central star of mass $M$. With an azimuthal magnetic field, this self-similar
MHD model provides an equatorial structure in the form of an axisymmetric torus
with nested and closed toroidal magnetic field lines. In the absence of an
azimuthal magnetic field, this formulation models the basic features of bipolar
planetary nebulae. The evolution function, which accounts for the time
evolution of the system, has a bounded and an unbounded evolution track
governed respectively by a negative and positive energy density constant $H$.


title:
The SCUBA Half-Degree Extragalactic Survey (SHADES) - VIII. The Nature
  of Faint Submm Galaxies in SHADES, SWIRE and SXDF Surveys

abstract:
  We present the optical-to-submm spectral energy distributions for 33 radio &
mid-IR identified submillimetre galaxies discovered via the SHADES 850 micron
SCUBA imaging in the Subaru-XMM Deep Field (SXDF). Optical data for the sources
comes from the Subaru-XMM Deep Field (SXDF) and mid- and far-IR fluxes from
SWIRE. We obtain photometric redshift estimates for our sources using optical
and IRAC 3.6 and 4.5 micron fluxes. We then fit spectral energy distribution
(SED) templates to the longer wavelength data to determine the nature of the
far-IR emission that dominates the bolometric luminosity of these sources. The
infrared template fits are also used to resolve ambiguous identifications and
cases of redshift aliasing. The redshift distribution obtained broadly matches
previous results for submm sources and on the SHADES SXDF field. Our template
fitting finds that AGN, present in about 10% of sources, do not contribute
significantly to their bolometric luminosity. Dust heating by starbursts, with
either Arp220 or M82 type SEDs, appears to be responsible for the luminosity in
most sources (23/33 are fitted by Arp220 templates, 2/33 by the warmer M82
templates). 8/33 sources, in contrast, are fit by a cooler cirrus dust
template, suggesting that cold dust has a role in some of these highly luminous
objects. Three of our sources appear to have multiple identifications or
components at the same redshift, but we find no statistical evidence that close
associations are common among our SHADES sources. Examination of rest-frame K
-band luminosity suggests that 'downsizing' is underway in the submm galaxy
population, with lower redshift systems lying in lower mass host galaxies. Of
our 33 identifications six are found to be of lower reliability but their
exclusion would not significantly alter our conclusions.


title: Fast unfolding of communities in large networks

abstract:
  We propose a simple method to extract the community structure of large
networks. Our method is a heuristic method that is based on modularity
optimization. It is shown to outperform all other known community detection
method in terms of computation time. Moreover, the quality of the communities
detected is very good, as measured by the so-called modularity. This is shown
first by identifying language communities in a Belgian mobile phone network of
2.6 million customers and by analyzing a web graph of 118 million nodes and
more than one billion links. The accuracy of our algorithm is also verified on
ad-hoc modular networks. .

categories: physics.soc-ph cond-mat.stat-mech cs.CY cs.DS


title: Minimal Niven numbers

abstract:
  Define a(k,q) to be the smallest positive multiple of k such that the sum of
its digits in base q is equal to k.
  The asymptotic behavior, lower and upper bound estimates of a(k,q) are
investigated. A characterization of the minimality condition is also
considered.


title:
Conservation of dielectric constant upon amorphization in perovskite
  oxides

abstract:
  We report calculations indicating that amorphous RAO$_3$ oxides, with R and A
trivalent cations, have approximately the same static dielectric constant as
their perovskite crystal phase. The effect is due to the disorder-activated
polar response of non-polar crystal modes at low frequency, which compensates a
moderate but appreciable reduction of the ionic dynamical charges. The
dielectric response was studied via density-functional perturbation theory.
Amorphous samples were generated by molecular dynamics melt-and-quench
simulations.


title:
Additivity of the Renyi entropy of order 2 for
  positive-partial-transpose-inducing channels

abstract:
  We prove that the minimal Renyi entropy of order 2 (RE2) output of a
positive-partial-transpose(PPT)-inducing channel joint to an arbitrary other
channel is equal to the sum of the minimal RE2 output of the individual
channels. PPT-inducing channels are channels with a Choi matrix which is bound
entangled or separable. The techniques used can be easily recycled to prove
additivity for some non-PPT-inducing channels such as the depolarizing and
transpose depolarizing channels, though not all known additive channels. We
explicitly make the calculations for generalized Werner-Holevo channels as an
example of both the scope and limitations of our techniques.


title:
Origin of the colossal positive and negative thermal expansion in
  Ag$_3$[Co(CN)$_6$]: an {\it ab initio} Density Functional Theory study

abstract:
  DFT calculations have been used to provide insights into the origin of the
colossal positive and negative thermal expansion in Ag$_3$[Co(CN)$_6]$. The
results confirm that the positive expansion within the trigonal basal plane and
the negative expansion in the orthogonal direction are coupled due to the
existence of a network defined by nearly-rigid bonds within the chains of
Co--C--N--Ag--N--C--Co linkages. The origin of the colossal values of the
coefficients of thermal expansion arise from an extremely shallow energy
surface that allows a flexing of the structure with small energy cost. The
thermal expansion can be achieved with a modest value of the overall
Gr\"{u}neisen parameter. The energy surface is so shallow that we need to
incorporate a small empirical dispersive interaction to give ground-state
lattice parameters that match experimental values at low temperature. We
compare the results with DFT calculations on two isostructural systems:
H$_3$[Co(CN)$_6$], which is known to have much smaller values of the
coefficients of thermal expansion, and Au$_3$[Co(CN)$_6$], which has not yet
been synthesised but which is predicted by our calculations to be another
candidate material for showing colossal positive and negative thermal
expansion.


title:
$\mu \to e \gamma$ and $\tau \to l \gamma$ decays in the fermion triplet
  seesaw model

abstract:
  In the framework of the seesaw models with triplets of fermions, we evaluate
the decay rates of $\mu \to e \gamma$ and $\tau \to l \gamma$ transitions. We
show that although, due to neutrino mass constraints, those rates are in
general expected to be well under the present experimental limits, this is not
necessarily always the case. Interestingly enough, the observation of one of
those decays in planned experiments would nevertheless contradict bounds
stemming from present experimental limits on the $\mu \to eee$ and $\tau \to 3
l$ decay rates. Such detection of radiative decays would therefore imply that
there exist sources of lepton flavour violation not associated to triplet
fermions.


title: Conformal Properties of an Evaporating Black Hole Model

abstract:
  We use a new, conformally-invariant method of analysis to test incomplete
null geodesics approaching the singularity in a model of an evaporating black
hole for the possibility of extensions of the conformal metric. In general, a
local conformal extension is possible from the future but not from the past.


title:
Theory of DNA translocation through narrow ion channels and nanopores
  with charged walls

abstract:
  Translocation of a single stranded DNA through genetically engineered
$\alpha$-hemolysin channels with positively charged walls is studied. It is
predicted that transport properties of such channels are dramatically different
from neutral wild type $\alpha$-hemolysin channel. We assume that the wall
charges compensate the fraction $x$ of the bare charge $q_{b}$ of the DNA piece
residing in the channel. Our prediction are as follows (i) At small
concentration of salt the blocked ion current decreases with $x$. (ii) The
effective charge $q$ of DNA piece, which is very small at $x = 0$ (neutral
channel) grows with $x$ and at $x=1$ reaches $q_{b}$. (iii) The rate of DNA
capture by the channel exponentially grows with $x$. Our theory is also
applicable to translocation of a double stranded DNA in narrow solid state
nanopores with positively charged walls.


title:
Chain metallicity and antiferro-paramagnetism competition in underdoped
  YBa$_2$Cu$_3$O$_{6+x}$: a first principles description

abstract:
  We describe from advanced first principles calculations the energetics of
oxygen doping and its relation to insulator-metal transitions in underdoped
YBa$_2$Cu$_3$O$_{6+x}$. We find a strong tendency of doping oxygens to order
into non-magnetic Cu$^{1+}$O$_x$ chains at any $x$. Ordering produces
one-dimensional metallic bands, while configurations with non-aligned oxygens
are insulating. The Cu$^{2+}$O$_2$ planes remain insulating and
antiferromagnetic up to a threshold between $x$=0.25 and 0.5, above which a
paramagnetic normal-metal state prevails. The in-plane antiferro-paramagnetic
competition depends on $x$, but only weakly on the ordering state of the
chains.


title:
Quantum interference structures in trapped ion dynamics beyond the
  Lamb-Dicke and rotating wave approximations

abstract:
  We apply wave packet methods to study an ion-trap system in the strong
excitation regime imposing neither the rotating wave nor the Lamb-Dicke
approximations. By this approach we show the existence of states with
restricted phase space evolution, as a genuine consequence of quantum
interference between wave packet fractions. A particular instance of such a
state oscillates between maximal entanglement and pure disentanglement between
the constitute subsystems. The characteristic crossover time is very rapid
making them suitable for state preparations of EPR or Schrodinger cat states.
Over longer time periods the dynamics of these states exhibits collapse-revival
patterns with well resolved fractional revivals in autocorrelation, inversion
and entanglement.


title:
Neutron star long term cooling - Joule heating in magnetized neutron
  stars

abstract:
  We present two-dimensional simulations for the cooling of neutron stars with
strong magnetic fields (B > 1e13 Gauss). We study how the cooling curves are
influenced by magnetic field decay. We show that the Joule heating effects are
very large and in some cases control the thermal evolution. We characterize the
temperature anisotropy induced by the magnetic field and predict the surface
temperature distribution for the early and late stages of the evolution of
isolated neutron stars, comparing our results with available observational data
of isolated neutron stars.


title:
Schwinger-Dyson operators as invariant vector fields on a matrix-model
  analogue of the group of loops

abstract:
  For a class of large-N multi-matrix models, we identify a group G that plays
the same role as the group of loops on space-time does for Yang-Mills theory. G
is the spectrum of a commutative shuffle-deconcatenation Hopf algebra that we
associate to correlations. G is the exponential of the free Lie algebra. The
generating series of correlations is a function on G and satisfies quadratic
equations in convolution. These factorized Schwinger-Dyson or loop equations
involve a collection of Schwinger-Dyson operators, which are shown to be
right-invariant vector fields on G, one for each linearly independent primitive
of the Hopf algebra. A large class of formal matrix models satisfying these
properties are identified, including as special cases, the zero momentum limits
of the Gaussian, Chern-Simons and Yang-Mills field theories. Moreover, the
Schwinger-Dyson operators of the continuum Yang-Mills action are shown to be
right-invariant derivations of the shuffle-deconcatenation Hopf algebra
generated by sources labeled by position and polarization.


title:
$t$-periodic light rays in conformally stationary spacetimes via Finsler
  geometry

abstract:
  In this paper we prove several multiplicity results of $t$-periodic light
rays in conformally stationary spacetimes using the Fermat metric and the
extensions of the classical theorems of Gromoll-Meyer and Bangert-Hingston to
Finsler manifolds. Moreover, we exhibit some stationary spacetimes with a
finite number of $t$-periodic light rays and compute a lower bound for the
period of the light rays when the flag curvature of the Fermat metric is
$\eta$-pinched.


title:
Spin models on random graphs with controlled topologies beyond degree
  constraints

abstract:
  We study Ising spin models on finitely connected random interaction graphs
which are drawn from an ensemble in which not only the degree distribution
$p(k)$ can be chosen arbitrarily, but which allows for further fine-tuning of
the topology via preferential attachment of edges on the basis of an arbitrary
function Q(k,k') of the degrees of the vertices involved. We solve these models
using finite connectivity equilibrium replica theory, within the replica
symmetric ansatz. In our ensemble of graphs, phase diagrams of the spin system
are found to depend no longer only on the chosen degree distribution, but also
on the choice made for Q(k,k'). The increased ability to control interaction
topology in solvable models beyond prescribing only the degree distribution of
the interaction graph enables a more accurate modeling of real-world
interacting particle systems by spin systems on suitably defined random graphs.


title: Towards Theory of Piecewise Linear Dynamical Systems

abstract:
  In this paper, we consider a planar dynamical system with a piecewise linear
function containing an arbitrary number (but finite) of dropping sections and
approximating some continuous nonlinear function. Studying all possible local
and global bifurcations of its limit cycles, we prove that such a piecewise
linear dynamical system with $k$ dropping sections and $2k+1$ singular points
can have at most $k+2$ limit cycles, $k+1$ of which surround the foci one by
one and the last, $(k+2)$-th, limit cycle surrounds all of the singular points
of this system.


title: Bruhat-Chevalley order on the rook monoid

abstract:
  The rook monoid $R_n$ is the finite monoid whose elements are the 0-1
matrices with at most one nonzero entry in each row and column. The group of
invertible elements of $R_n$ is isomorphic to the symmetric group $S_n$. The
natural extension to $R_n$ of the Bruhat-Chevalley ordering on the symmetric
group is defined in \cite{Renner86}. In this paper, we find an efficient,
combinatorial description of the Bruhat-Chevalley ordering on $R_n$. We also
give a useful, combinatorial formula for the length function on $R_n$.


title: Light Vector Mesons in the Nuclear Medium

abstract:
  The light vector mesons ($\rho$, $\omega$, and $\phi$) were produced in
deuterium, carbon, titanium, and iron targets in a search for possible
in-medium modifications to the properties of the $\rho$ meson at normal nuclear
densities and zero temperature. The vector mesons were detected with the CEBAF
Large Acceptance Spectrometer (CLAS) via their decays to $e^{+}e^{-}$. The rare
leptonic decay was chosen to reduce final-state interactions. A combinatorial
background was subtracted from the invariant mass spectra using a
well-established event-mixing technique. The $\rho$ meson mass spectrum was
extracted after the $\omega$ and $\phi$ signals were removed in a nearly
model-independent way. Comparisons were made between the $\rho$ mass spectra
from the heavy targets ($A > 2$) with the mass spectrum extracted from the
deuterium target. With respect to the $\rho$-meson mass, we obtain a small
shift compatible with zero. Also, we measure widths consistent with standard
nuclear many-body effects such as collisional broadening and Fermi motion.


title: Crossover between hydrodynamic and kinetic modes in binary liquid alloys

abstract:
  Inelastic x-ray scattering (IXS) measurements of the dynamic structure factor
in liquid Na57K43, sensitive to the atomic-scale coarse graining, reveal a
sound velocity value exceeding the long wavelength, continuum value and
indicate the coexistence of two phonon-like modes. Applying Generalized
Collective Mode (GCM) analysis scheme, we show that the positive dispersion of
the sound velocity occurs in a wavelength region below the crossover from
hydrodynamic to atom-type excitations and, therefore, it can not be explained
as sound propagation over the light specie (Na) network. The present result
experimentally proves the existence of positive dispersion in a binary mixture
due to a relaxation process, as opposed to fast sound phenomena.


title: The NLO multileg working group: summary report

abstract:
  This report summarizes the activities of the NLM working group of the
Workshop "Physics at TeV Colliders", Les Houches, France, 11-29 June, 2007.


title: Coherence and oscillations of cosmic neutrinos

abstract:
  For cosmic neutrinos we study the conditions and the effects of the coherence
loss as well as coherent broadening of the spectrum. We evaluate the width of
the neutrino wavepacket produced by charged particles under various
circumstances: in an interaction-free environment, in a radiation-dominated
medium (typical of the sources of the gamma ray bursts) and in the presence of
a magnetic field. The effect of the magnetic field on the wavepacket size
appears to be more important than the scattering. If the magnetic field at the
source is larger than $\sim$10 Gauss, the coherence of neutrinos will be lost
while traveling over cosmological distances. Various applications of these
results have been considered. We find that for large magnetic fields ($B> 10^9$
Gauss) and high energies ($E_\nu>{\rm PeV}$), "coherent broadening" can modify
the energy spectrum of neutrinos. In the coherent case, averaging out the
oscillatory terms of the probabilities does not induce any statistical
uncertainty beyond what expected in the absence of these terms. A deviation
from the standard quantum mechanics that preserves average energy and unitarity
cannot alter the picture.


title:
X-ray irradiation in XTE J1817-330 and the inner radius of the truncated
  disc in the hard state

abstract:
  The key aspect of the very successful truncated disc model for the low/hard
X-ray spectral state in black hole binaries is that the geometrically thin disc
recedes back from the last stable orbit at the transition to this state. This
has recently been challenged by direct observations of the low/hard state disc
from CCD data. We reanalyze the Swift and RXTE campaign covering the 2006
outburst of XTE J1817-330 and show that these data actually strongly support
the truncated disc model as the transition spectra unambiguously show that the
disc begins to recede as the source leaves the disc dominated soft state. The
disc radius inferred for the proper low/hard state is less clear-cut, but we
show that the effect of irradiation from the energetically dominant hot plasma
leads to an underestimate of the disc radius by a factor of 2-3 in this state.
This may also produce the soft excess reported in some hard-state spectra. The
inferred radius becomes still larger when the potential difference in stress at
the inner boundary, increased colour temperature correction from incomplete
thermalization of the irradiation, and loss of observable disc photons from
Comptonization in the hot plasma are taken into account. We conclude that the
inner disc radius in XTE J1817-330 in the low/hard spectral state is at least
6-8 times that seen in the disc dominated high/soft state, and that recession
of the inner disc is the trigger for the soft--hard state transition, as
predicted by the truncated disc models.


title:
Anomaly Holography, the Wess-Zumino-Witten Term, and Electroweak
  Symmetry Breaking

abstract:
  I consider anomalies in effective field theories (EFTs) of gauge fields
coupled to fermions on an interval in AdS_5, and their holographic duals. The
anomalies give rise to constraints on the consistent EFT description, which are
stronger than the usual four-dimensional anomaly cancellation condition for the
zero modes. Even though the anomalies occur on both boundaries of the interval,
corresponding to both the UV and the IR of the holographic dual, they are
nevertheless consistent with the non-renormalization of the anomaly and the 't
Hooft matching condition. They give rise, in general, to a Wess-Zumino-Witten
(WZW) term in the four-dimensional, low-energy effective action, whose form I
compute. Finally I discuss the relevance to holographic models of electroweak
symmetry breaking. I show that the so-called `minimal composite Higgs models'
have a consistent EFT description without a WZW term. In contrast, a variant of
an earlier model of Contino, Nomura, and Pomarol does have a WZW term.


title: Injective Simplicial Maps of the Arc Complex on Nonorientable Surfaces

abstract:
  We prove that each injective simplicial map from the arc complex of a
compact, connected, nonorientable surface with nonempty boundary to itself is
induced by a homeomorphism of the surface. We also prove that the automorphism
group of the arc complex is isomorphic to the quotient of the mapping class
group of the surface by its center.


title: Abelian Hurwitz-Hodge integrals

abstract:
  Hodge classes on the moduli space of admissible covers with monodromy group G
are associated to irreducible representations of G. We evaluate all linear
Hodge integrals over moduli spaces of admissible covers with abelian monodromy
in terms of multiplication in an associated wreath group algebra. In case G is
cyclic and the representation is faithful, the evaluation is in terms of double
Hurwitz numbers. In case G is trivial, the formula specializes to the
well-known result of Ekedahl-Lando-Shapiro-Vainshtein for linear Hodge
integrals over the moduli space of curves in terms of single Hurwitz numbers.


title: Ozsvath-Szabo and Rasmussen invariants of cable knots

abstract:
  We study the behavior of the Ozsvath-Szabo and Rasmussen knot concordance
invariants tau and s on K(m,n), the (m,n)-cable of a knot K where m and n are
relatively prime. We show that for every knot K and for any fixed positive
integer m, both of the invariants evaluated on K(m,n) differ from their value
on the torus knot T(m,n) by a fixed constant for all but finitely many n>0.
Combining this result together with Hedden's extensive work on the behavior of
tau on (m,mr+1)-cables yields bounds on the value of tau on any (m,n)-cable of
K. In addition, several of Hedden's obstructions for cables bounding complex
curves are extended.


title:
Possible discovery of a nonlinear tail and second-order quasinormal
  modes in black hole ringdown

abstract:
  We investigate the nonlinear evolution of black hole ringdown in the
framework of higher-order metric perturbation theory. By solving the
initial-value problem of a simplified nonlinear field model analytically as
well as numerically, we find that (i) second-order quasinormal modes (QNMs) are
indeed excited at frequencies different from those of first-order QNMs, as
predicted recently. We also find serendipitously that (ii) late-time evolution
is dominated by a new type of power-law tail. This ``second-order power-law
tail'' decays more slowly than any late-time tails known in the first-order
(i.e., linear) perturbation theory, and is generated at the wavefront of the
first-order perturbation by an essentially nonlinear mechanism. These nonlinear
components should be particularly significant for binary black hole
coalescences, and could open a new precision science in gravitational wave
studies.


title: Normal scalar curvature conjecture and its applications

abstract:
  In this paper, we proved the Normal Scalar Curvature Conjecture and the
Bottcher-Wenzel Conjecture. We also established some new pinching theorems for
minimal submanifolds in spheres.


title: Non-linear ground state representations and sharp Hardy inequalities

abstract:
  We determine the sharp constant in the Hardy inequality for fractional
Sobolev spaces. To do so, we develop a non-linear and non-local version of the
ground state representation, which even yields a remainder term. From the sharp
Hardy inequality we deduce the sharp constant in a Sobolev embedding which is
optimal in the Lorentz scale. In the appendix, we characterize the cases of
equality in the rearrangement inequality in fractional Sobolev spaces.


title: Dielectric function of the QCD vacuum

abstract:
  It is shown that the inverse of the ghost form factor in the Hamilton
approach to Yang-Mills theory in Coulomb gauge can be interpreted as the color
dielectric function of the QCD vacuum. Furthermore the horizon condition to the
ghost form factor implies that in the infrared the QCD vacuum is a perfect
color diaelectric medium and therefore a dual superconductor. The dielectric
function is explicitly calculated within a previously developed variational
approach, using a specific ansatz for the vacuum wave functional.


title:
Early emission of rising optical afterglows: The case of GRB 060904B and
  GRB 070420

abstract:
  We present the time-resolved optical emission of gamma-ray bursts GRB 060904B
and GRB 070420 during their prompt and early afterglow phases. We used time
resolved photometry from optical data taken by the TAROT telescope and time
resolved spectroscopy at high energies from the Swift spacecraft instrument.
The optical emissions of both GRBs are found to increase from the end of the
prompt phase, passing to a maximum of brightness at t_{peak}=9.2 min and 3.3
min for GRB 060904B and GRB 070420 respectively and then decrease. GRB 060904B
presents a large optical plateau and a very large X-ray flare. We argue that
the very large X-flare occurring near t_{peak} is produced by an extended
internal engine activity and is only a coincidence with the optical emission.
GRB 070420 observations would support this idea because there was no X-flare
during the optical peak. The nature of the optical plateau of GRB 060904B is
less clear and might be related to the late energy injection.


title:
A Model for the Chromosphere/Wind of 31 Cygni and its Implications for
  Single Stars

abstract:
  I develop a detailed empirical model for the chromosphere and wind of 31 Cyg
based on a previously published analysis of IUE spectra from the 1993 eclipse
and on the thermodynamics of how the wind must be driven. I then use this model
to interpret observations of single supergiant stars and to assess the evidence
that their winds are fundamentally different from those of supergiants in the
binary systems. This model naturally predicts a certain level of clumping of
the gas to balance the pressure that drives the wind. It also predicts that
anisotropic turbulence, such as would result from transverse displacements of
Alfven waves directed along radial magnetic flux lines, would not give the
roughly Gaussian profiles of emission lines seen in cool giant stars.
Furthermore, it implies that C II] may not tell us much at all about general
conditions in chromospheres. Finally, I speculate that chaotic magnetic fields,
in dynamical equilibrium with the gas of the wind, are the actual driving
mechanism.


title:
Numerical observation of Hawking radiation from acoustic black holes in
  atomic Bose-Einstein condensates

abstract:
  We report numerical evidence of Hawking emission of Bogoliubov phonons from a
sonic horizon in a flowing one-dimensional atomic Bose-Einstein condensate. The
presence of Hawking radiation is revealed from peculiar long-range patterns in
the density-density correlation function of the gas. Quantitative agreement
between our fully microscopic calculations and the prediction of analog models
is obtained in the hydrodynamic limit. New features are predicted and the
robustness of the Hawking signal against a finite temperature discussed.


title: Discrete Fourier analysis on a dodecahedron and a tetrahedron

abstract:
  A discrete Fourier analysis on the dodecahedron is studied, from which
results on a tetrahedron is deduced by invariance. The results include Fourier
analysis in trigonometric functions, interpolation and cubature formulas on
these domains. In particular, a trigonometric Lagrange interpolation on the
tetrahedron is shown to satisfy an explicit compact formula and the Lebesgue
constant of the interpolation is shown to be in the order of $(\log n)^3$.


title:
On a class of hypoelliptic operators with unbounded coefficients in
  ${\matbb R}^N$

abstract:
  We consider a class of non-trivial perturbations ${\mathscr A}$ of the
degenerate Ornstein-Uhlenbeck operator in ${\mathbb R}^N$. In fact we perturb
both the diffusion and the drift part of the operator (say $Q$ and $B$)
allowing the diffusion part to be unbounded in ${\mathbb R}^N$. Assuming that
the kernel of the matrix $Q(x)$ is invariant with respect to $x\in {\mathbb
R}^N$ and the Kalman rank condition is satisfied at any $x\in{\mathbb R}^N$ by
the same $m<N$, and developing a revised version of Bernstein's method we prove
that we can associate a semigroup $\{T(t)\}$ of bounded operators (in the space
of bounded and continuous functions) with the operator ${\mathscr A}$.
Moreover, we provide several uniform estimates for the spatial derivatives of
the semigroup $\{T(t)\}$ both in isotropic and anisotropic spaces of
(H\"older-) continuous functions. Finally, we prove Schauder estimates for some
elliptic and parabolic problems associated with the operator ${\mathscr A}$.


title:
SO(10) SUSY GUTs, the gravitino problem, non-thermal leptogenesis and
  axino dark matter

abstract:
  Simple SUSY GUT models based on the gauge group SO(10) require t-b-\tau
Yukawa coupling unification, in addition to gauge coupling and matter
unification. The Yukawa coupling unification places strong constraints on the
expected superparticle mass spectrum, with scalar masses \sim 10 TeV while
gaugino masses are quite light. A problem generic to all supergravity models
comes from overproduction of gravitinos in the early universe: if gravitinos
are unstable, then their late decays may destroy the predictions of Big Bang
nucleosynthesis. We present a Yukawa-unified SO(10) SUSY GUT scenario which
avoids the gravitino problem, gives rise to the correct matter-antimatter
asymmetry via non-thermal leptogenesis, and is consistent with the
WMAP-measured abundance of cold dark matter due to the presence of an axino
LSP. To maintain a consistent cosmology for Yukawa-unified SUSY models, we
require a re-heat temperature T_R\sim 10^6-10^7 GeV, an axino mass around \sim
0.1-10 MeV, and a PQ breaking scale f_a\sim 10^{12} GeV.


title: Nonsequential two-photon double ionization of helium

abstract:
  We present accurate time-dependent ab initio calculations on fully
differential and total integrated (generalized) cross sections for the
nonsequential two-photon double ionization of helium at photon energies from 40
to 54 eV. Our computational method is based on the solution of the
time-dependent Schroedinger equation and subsequent projection of the wave
function onto Coulomb waves. We compare our results with other recent
calculations and discuss the emerging similarities and differences. We
investigate the role of electronic correlation in the representation of the
two-electron continuum states, which are used to extract the ionization yields
from the fully correlated final wave function. In addition, we study the
influence of the pulse length and shape on the cross sections in time-dependent
calculations and address convergence issues.


title: Accumulating evidence for nonstandard leptonic decays of D_s mesons

abstract:
  The measured rate for D_s -> l nu decays, where l is a muon or tau, is larger
than the standard model prediction, which relies on lattice QCD, at the 3.8
sigma level. We discuss how robust the theoretical prediction is, and we show
that the discrepancy with experiment may be explained by a charged Higgs boson
or a leptoquark.


title: On the nature of the plasma equilibrium

abstract:
  We calculate the energy of a homogeneous one component plasma and find that
the energy is lower for correlated motions of the particles as compared to
uncorrelated motion. Our starting point is the conserved approximately
relativistic (Darwin) energy for a system of electromagnetically interacting
particles that arises from the neglect of radiation. For the idealized model of
a homogeneous one component plasma the energy only depends on the particle
canonical momenta and the vector potential. The vector potential is then
calculated in terms of the canonical momenta using recent theoretical advances
and the plasma Hamiltonian is obtained. The result can be understood either as
due to the energy lowering caused by the attraction of parallel currents or,
alternatively, as due to the inductive inertia associated with the flow of net
current.


title: Metastable vacua and geometric deformations

abstract:
  We study the geometric interpretation of metastable vacua for systems of D3
branes at non isolated toric deformable singularities. Using the L^{aba}
examples, we investigate the relations between the field theoretic susy
breaking and restoration and the complex deformations of the CY singularities.


title:
Intuitive Source Code Visualization Tools for Improving Student
  Comprehension: BRICS

abstract:
  Even relatively simple code analysis can be a daunting task for many first
year students. Perceived complexity, coupled with foreign and harsh syntax,
often outstrips the ability for students to take in what they are seeing in
terms of their verbal memory. That is, first year students often lack the
experience to encode critical building blocks in source code, and their
interrelationships, into their own words. We believe this argues for the need
for IDEs to provide additional support for representations that would appeal
directly to visual memory. In this paper, we examine this need for intuitive
source code visualization tools that are easily accessible to novice
programmers, discuss the requirements for such a tool, and suggest a novel idea
that takes advantage of human peripheral vision to achieve stronger overall
code structure awareness.


title: Coexistence of distinct charge fluctuations in $\theta$-(BEDT-TTF)$_2$X

abstract:
  Using the Lanczos exact-diagonalization and density-matrix renormalization
group methods, we study the extended Hubbard model at quarter filling defined
on the anisotropic triangular lattice. We focus on charge ordering (CO)
phenomena induced by onsite and intersite Coulomb interactions. We determine
the ground-state phase diagram including three CO phases, i.e., diagonal,
vertical, and three-fold CO phases, based on the calculated results of the hole
density and double occupancy. We also calculate the dynamical density-density
correlation functions and find possible coexistence of the diagonal and
three-fold charge fluctuations in a certain parameter region where the onsite
and intersite interactions compete. Furthermore, the characteristic features of
the optical conductivity for each CO phase are discussed.


title:
A young double stellar cluster in a HII region, emerging from its parent
  molecular cloud

abstract:
  We report the properties of a new young double stellar cluster in the region
towards IRAS 07141-0920 contained in the HII region Sh2-294. High-resolution
optical UBVRI and Halpha images, near-infrared JHKs and H2 filter images were
used to make photometric and morphological studies of the point sources and the
nebula seen towards Sh2-294. The optical images reveal an emission nebula with
very rich morphological details, composed mainly of UV scattered light and of
Halpha emission. Contrasting with the bright parts of the nebula, opaque,
elongated patches are seen. Our optical photometry confirms that the
illuminator of the nebula is likely to be a B0.5V star located at a distance of
about 3.2 kpc. Our near-IR images reveal an embedded cluster, extending for
about 2 pc and exhibiting sub-clustering: a denser, more condensed, sub-cluster
surrounding the optical high-mass B0.5V illuminator star; and a more embedded,
optically invisible, sub-cluster located towards the eastern, dark part of the
nebula and including the luminous MSX source G224.1880+01.2407, a massive
protostellar candidate that could be the origin of jets and extended features
seen at 2.12 micron. The double cluster appears to be clearing the remaining
molecular material of the parent cloud, creating patches of lower extinction
and allowing some of the least reddened members to be detected in the optical
images. We find 12 MS and 143 PMS members using 3 different methods: comparison
with isochrones in optical colour-magnitude diagrams, detection of near-IR
excess, and presence of Halpha emission. The most massive star fits a 4 Myr
post-MS isochrone. The age of the optically selected PMS population is
estimated to be 7-8 Myr. The IR-excess population shows sub-clustering on
scales as small as 0.23 pc and is probably much younger.


title: Randall-Sundrum model with $\lambda<0$ and bulk brane viscosity

abstract:
  We study the effect of the inclusion of bulk brane viscosity on brane world
(BW) cosmology in the framework of the Eckart's theory, we focus in the
Randall-Sundrum model with negative tension on the brane.