title:
Reciprocal best hits are not a logically sufficient condition for
  orthology

abstract:
  It is common to use reciprocal best hits, also known as a boomerang
criterion, for determining orthology between sequences. The best hits may be
found by blast, or by other more recently developed algorithms. Previous work
seems to have assumed that reciprocal best hits is a sufficient but not
necessary condition for orthology. In this article, I explain why reciprocal
best hits cannot logically be a sufficient condition for orthology. If
reciprocal best hits is neither sufficient nor necessary for orthology, it
would seem worthwhile to examine further the logical foundations of some
unsupervised algorithms that are used to identify orthologs.


title:
DIA-MCIS. An Importance Sampling Network Randomizer for Network Motif
  Discovery and Other Topological Observables in Transcription Networks

abstract:
  Transcription networks, and other directed networks can be characterized by
some topological observables such as for example subgraph occurrence (network
motifs). In order to perform such kind of analysis, it is necessary to be able
to generate suitable randomized network ensembles. Typically, one considers
null networks with the same degree sequences of the original ones. The commonly
used algorithms sometimes have long convergence times, and sampling problems.
We present here an alternative, based on a variant of the importance sampling
Montecarlo developed by Chen et al. [1].


title: Towards a Completion of Archimedes' Treatise on Floating Bodies

abstract:
  In his treatise on floating bodies Archimedes determines the equilibrium
positions of a floating paraboloid segment, but only in the case when the basis
of the segment is either completely outside of the fluid or completely
submerged. Here we give a mathematical model for the remaining case, i.e., two
simple conditions which describe the equilibria in closed form. We provide
tools for finding all equilibria in a reliable way and for the classification
of these equilibria. This paper can be considered as a continuation of a recent
article of Rorres.


title:
On the spectrum of the Laplace operator of metric graphs attached at a
  vertex -- Spectral determinant approach

abstract:
  We consider a metric graph $\mathcal{G}$ made of two graphs $\mathcal{G}_1$
and $\mathcal{G}_2$ attached at one point. We derive a formula relating the
spectral determinant of the Laplace operator
$S_\mathcal{G}(\gamma)=\det(\gamma-\Delta)$ in terms of the spectral
determinants of the two subgraphs. The result is generalized to describe the
attachment of $n$ graphs. The formulae are also valid for the spectral
determinant of the Schr\"odinger operator $\det(\gamma-\Delta+V(x))$.


title: Number of points of Prym varieties over finite fields

abstract:
  We establish some upper and lower bounds for the number of rational points of
Prym varieties over finite fields.


title: Granular Rayleigh-Taylor Instability: Experiments and Simulations

abstract:
  A granular instability driven by gravity is studied experimentally and
numerically. The instability arises as grains fall in a closed Hele-Shaw cell
where a layer of dense granular material is positioned above a layer of air.
The initially flat front defined by the grains subsequently develops into a
pattern of falling granular fingers separated by rising bubbles of air. A
transient coarsening of the front is observed right from the start by a finger
merging process. The coarsening is later stabilized by new fingers growing from
the center of the rising bubbles. The structures are quantified by means of
Fourier analysis and quantitative agreement between experiment and computation
is shown. This analysis also reveals scale invariance of the flow structures
under overall change of spatial scale.


title: The Astrophysics of Early Galaxy Formation

abstract:
  These lectures summarize our basic understanding of the emergence of cosmic
structures, the epoch of first light, the survival of early substructure in
present-day galaxy halos.


title:
Influence of the Magnetic Coupling Process on the Advection Dominated
  Accretion Flows around Black Holes

abstract:
  A large-scale closed magnetic field can transfer angular momentum and energy
between a black hole (BH) and its surrounding accretion flow. We investigate
the effects of this magnetic coupling (MC) process on the dynamics of a hot
accretion flow (e.g., an advection dominated accretion flow, hereafter ADAF).
The energy and angular momentum fluxes transported by the magnetic field are
derived by an equivalent circuit approach. For a rapidly rotating BH, it is
found that the radial velocity and the electron temperature of the accretion
flow decrease, whereas the ion temperature and the surface density increase.
The significance of the MC effects depends on the value of the viscous
parameter \alpha. The effects are obvious for \alpha=0.3 but nearly ignorable
for \alpha=0.1. For a BH with specific angular momentum, a_*=0.9, and
\alpha=0.3, we find that for reasonable parameters the radiative efficiency of
a hot accretion flow can be increased by about 30%.


title:
Effect of Electron Interaction on Statistics of Conductance Oscillations
  in Open Quantum Dots: Does the Dephasing Time Saturate?

abstract:
  We perform self-consistent quantum transport calculations in open quantum
dots taking into account the effect of electron interaction. We demonstrative
that in the regime of the ultralow temperatures $2\pi k_BT\lesssim\Delta$
($\Delta $ being the mean level spacing), the electron interaction strongly
affects the conductance oscillations and their statistics leading to a drastic
deviation from the corresponding predictions for noninteracting electrons. In
particular, it causes smearing of conductance oscillations, which is similar to
the effect of temperature or inelastic scattering. For $2\pi k_BT\gtrsim\Delta$
the influence of electron interaction on the conductance becomes strongly
diminished. Our calculations (that are free from phenomenological parameters of
the theory) are in good quantitative agreement with the observed ultralow
temperature statistics (Huibers \textit{et al.}, Phys. Rev. Lett. \textbf{81},
1917 (1998)). Our findings question a conventional interpretation of the
ultralow temperature saturation of the coherence time in open dots which is
based on the noninteracting theories where the electron interaction is
neglected and the agrement with the experiment is achieved by introducing
additional phenomenological channels of dephasing.


title: A simple test for hidden variables in spin-1 system

abstract:
  We resolve an old problem about the existence of hidden parameters in a
three-dimensional quantum system by constructing an appropriate Bell's type
inequality. This reveals a nonclassical nature of most spin-$1$ states. We
shortly discuss some physical implications and an underlying cause of this
nonclassical behavior, as well as a perspective of its experimental
verification.


title: States of the Dirac equation in confining potentials

abstract:
  We study the Dirac equation in confining potentials with pure vector
coupling, proving the existence of metastable states with longer and longer
lifetimes as the non-relativistic limit is approached and eventually merging
with continuity into the Schr\"odinger bound states. We believe that the
existence of these states could be relevant in high energy model construction
and in understanding possible resonant scattering effects in systems like
Graphene. We present numerical results for the linear and the harmonic cases
and we show that the the density of the states of the continuous spectrum is
well described by a sum of Breit-Wigner lines. The width of the line with
lowest positive energy, as expected, reproduces very well the Schwinger pair
production rate for a linear potential: we thus suggest a different way of
obtaining informations on the pair production in unbounded, non uniform
electric fields, where very little is known.


title: The Proton Elastic Form Factor Ratio at Low Momentum Transfer

abstract:
  High precision measurements of the proton elastic form factor ratio have been
made at four-momentum transfers, Q^2, between 0.2 and 0.5 GeV^2. The new data,
while consistent with previous results, clearly show a ratio less than unity
and significant differences from the central values of several recent
phenomenological fits. By combining the new form-factor ratio data with an
existing cross-section measurement, one finds that in this Q^2 range the
deviation from unity is primarily due to GEp being smaller than the dipole
parameterization.


title: Energy-minimizing two black holes initial data

abstract:
  An attempt to construct the ``ground state'' vacuum initial data for the
gravitational field surrounding two black holes is presented. The ground state
is defined as the gravitational initial data minimizing the ADM mass within the
class of data for which the masses of the holes and their distance are fixed.
To parameterize different geometric arrangements of the two holes (and,
therefore, their distance) we use an appropriately chosen scale factor. A
method for analyzing the variations of the ADM mass and the masses (areas) of
the horizons in terms of gravitational degrees of freedom is proposed. The
Misner initial data are analyzed in this context: it is shown that they do not
minimize the ADM mass.


title:
Recent progress constraining the nuclear equation of state from
  astrophysics and heavy ion reactions

abstract:
  The quest for the nuclear equation of state (EoS) at high densities and/or
extreme isospin is one of the longstanding problems of nuclear physics. Ab
initio calculations for the nuclear many-body problem make predictions for the
density and isospin dependence of the EoS far away from the saturation point of
nuclear matter. On the other hand, in recent years substantial progress has
been mode to constrain the EoS both, from the astrophysical side and from
accelerator based experiments. Heavy ion experiments support a soft EoS at
moderate densities while recent neutron star observations require a ``stiff''
high density behavior. Both constraints are discussed and shown to be in
agreement with the predictions from many-body theory.


title: Luminosity determination at HERA-B

abstract:
  A detailed description of an original method used to measure the luminosity
accumulated by the HERA-B experiment for a data sample taken during the
2002-2003 HERA running period is reported. We show that, with this method, a
total luminosity measurement can be achieved with a typical precision,
including overall systematic uncertainties, at a level of 5% or better. We also
report evidence for the detection of delta-rays generated in the target and
comment on the possible use of such delta rays to measure luminosity.


title: Magnification relations for Kerr lensing and testing Cosmic Censorship

abstract:
  A Kerr black hole with mass parameter m and angular momentum parameter a
acting as a gravitational lens gives rise to two images in the weak field
limit. We study the corresponding magnification relations, namely the signed
and absolute magnification sums and the centroid up to post-Newtonian order. We
show that there are post-Newtonian corrections to the total absolute
magnification and centroid proportional to a/m, which is in contrast to the
spherically symmetric case where such corrections vanish. Hence we also propose
a new set of lensing observables for the two images involving these
corrections, which should allow measuring a/m with gravitational lensing. In
fact, the resolution capabilities needed to observe this for the Galactic black
hole should in principle be accessible to current and near-future
instrumentation. Since a/m >1 indicates a naked singularity, a most interesting
application would be a test of the Cosmic Censorship conjecture. The technique
used to derive the image properties is based on the degeneracy of the Kerr lens
and a suitably displaced Schwarzschild lens at post-Newtonian order. A simple
physical explanation for this degeneracy is also given.


title: Displacement convexity and minimal fronts at phase boundaries

abstract:
  We show that certain free energy functionals that are not convex with respect
to the usual convex structure on their domain of definition, are strictly
convex in the sense of displacement convexity under a natural change of
variables. We use this to show that in certain cases, the only critical points
of these functionals are minimizers. This approach based on displacement
convexity permits us to treat multicomponent systems as well as single
component systems. The developments produce new examples of displacement convex
functionals, and, in the multi-component setting, jointly displacement convex
functionals.


title:
Unveiling the broad band X-ray continuum and iron line complex in Mkr
  841

abstract:
  Mkr 841 is a bright Seyfert 1 galaxy known to harbor a strong soft excess and
a variable K$\alpha$ iron line. It has been observed during 3 different periods
by XMM for a total cumulated exposure time of $\sim$108 ks. We present in this
paper a broad band spectral analysis of the complete EPIC-pn data sets. We were
able to test two different models for the soft excess, a relativistically
blurred photoionized reflection (\r model) and a relativistically smeared
ionized absorption (\a model). The continuum is modeled by a simple cut-off
power law and we also add a neutral reflection. These observations reveal the
extreme and puzzling spectral and temporal behaviors of the soft excess and
iron line. The 0.5-3 keV soft X-ray flux decreases by a factor 3 between 2001
and 2005 and the line shape appears to be a mixture of broad and narrow
components. We succeed in describing this complex broad-band 0.5-10 keV
spectral variability using either \r or \a to fit the soft excess. Both models
give statistically equivalent results even including simultaneous BeppoSAX data
up to 200 keV. Both models are consistent with the presence of remote
reflection characterized by a constant narrow component in the data. However
they differ in the presence of a broad line component present in \r but not
needed in \a. This study also reveals the sporadic presence of relativistically
redshifted narrow iron lines.


title:
Theory of New Quantum Oscillations in the Magnetoresistance of Graphene
  Layers

abstract:
  We present a theory presenting new quantum oscillations in the
magnetoresistance that are revealed as fine structures superimposed to the
Schubnikov-de-Haas oscillations. They may be observed in experiments on
graphene layers as fine structures that until now seem to have been overseen or
considered to be noise. These oscillations appear also in the behaviour of the
resistance as a function of the gate voltage that changes the number of
carriers or Fermi level. Experimental studies of these resonances should give
information of the uniformity and defects of the samples and represent a new
fine structure spectroscopy. Also the lateral sample size and quantum effects
may explain the absence of magnetoresistance in a few grapheme layers.
Experiments are proposed.


title:
The largest eigenvalues of finite rank deformation of large Wigner
  matrices: convergence and nonuniversality of the fluctuations

abstract:
  In this paper, we investigate the asymptotic spectrum of complex or real
Deformed Wigner matrices $(M_N)_N$ defined by $M_N=W_N/\sqrt{N}+A_N$ where
$W_N$ is an $N\times N$ Hermitian (resp., symmetric) Wigner matrix whose
entries have a symmetric law satisfying a Poincar\'{e} inequality. The matrix
$A_N$ is Hermitian (resp., symmetric) and deterministic with all but finitely
many eigenvalues equal to zero. We first show that, as soon as the first
largest or last smallest eigenvalues of $A_N$ are sufficiently far from zero,
the corresponding eigenvalues of $M_N$ almost surely exit the limiting
semicircle compact support as the size $N$ becomes large. The corresponding
limits are universal in the sense that they only involve the variance of the
entries of $W_N$. On the other hand, when $A_N$ is diagonal with a sole simple
nonnull eigenvalue large enough, we prove that the fluctuations of the largest
eigenvalue are not universal and vary with the particular distribution of the
entries of $W_N$.


title: Resurgent functions and splitting problems

abstract:
  The present text is an introduction to \'Ecalle's theory of resurgent
functions and alien calculus, in connection with problems of exponentially
small separatrix splitting. An outline of the resurgent treatment of Abel's
equation for resonant dynamics in one complex variable is included. The
emphasis is on examples of nonlinear difference equations, as a simple and
natural way of introducing the concepts.


title:
A quasianalyticity property for monogenic solutions of small divisor
  problems

abstract:
  We discuss the quasianalytic properties of various spaces of functions
suitable for one-dimensional small divisor problems. These spaces are formed of
functions C^1-holomorphic on certain compact sets K_j of the Riemann sphere (in
the Whitney sense), as is the solution of a linear or non-linear small divisor
problem when viewed as a function of the multiplier (the intersection of K_j
with the unit circle is defined by a Diophantine-type condition, so as to avoid
the divergence caused by roots of unity). It turns out that a kind of
generalized analytic continuation through the unit circle is possible under
suitable conditions on the K_j's.


title: Primeval galaxies

abstract:
  1) Introduction
  2) PopIII stars and galaxies: a "top-down" theoretical approach
  3) Lyman-alpha physics and astrophysics
  4) Distant/primeval galaxies: observations and main results


title: Treatment of electron viscosity in quantum conductance

abstract:
  In a recent paper Sai {\it et al.} [1] identified a correction $R^{dyn}$ to
the DC conductance of nanoscale junctions arising from dynamical
exchange-correlation ($XC$) effects within time-dependent density functional
theory. This quantity contributes to the total resistance through
$R=R_{s}+R^{dyn}$ where $R_{s}$ is the resistance evaluated in the absence of
dynamical $XC$ effects. In this Comment we show that the numerical estimation
of $R^{dyn}$ in example systems of the type they considered should be
considerably reduced, once a more appropriate form for the shear electron
viscosity $\eta$ is used.


title:
The structure of hypersonic shock waves using Navier-Stokes equations
  modified to include mass diffusion

abstract:
  Howard Brenner has recently proposed modifications to the Navier-Stokes
equations that relate to a diffusion of fluid volume that would be significant
for flows with high density gradients. In a previous paper (Greenshields &
Reese, 2007), we found these modifications gave good predictions of the viscous
structure of shock waves in argon in the range Mach 1.0-12.0 (while
conventional Navier-Stokes equations are known to fail above about Mach 2).
However, some areas of concern with this model were a somewhat arbitrary choice
of modelling coefficient, and potentially unphysical and unstable solutions. In
this paper, we therefore present slightly different modifications to include
molecule mass diffusion fully in the Navier-Stokes equations. These
modifications are shown to be stable and produce physical solutions to the
shock problem of a quality broadly similar to those from the family of extended
hydrodynamic models that includes the Burnett equations. The modifications
primarily add a diffusion term to the mass conservation equation, so are at
least as simple to solve as the Navier-Stokes equations; there are none of the
numerical implementation problems of conventional extended hydrodynamics
models, particularly in respect of boundary conditions. We recommend further
investigation and testing on a number of different benchmark non-equilibrium
flow cases.


title: Quantum gravity phenomenology via Lorentz violations

abstract:
  The search for a quantum theory of gravity has been one of the main aims of
theoretical physics for many years by now. However the efforts in this
direction have been often hampered by the lack of experimental/observational
tests able to select among, or at least constrain, the numerous quantum gravity
models proposed so far. This situation has changed in the last decade thanks to
the realization that some QG inspired violations of Lorentz symmetry could be
constrained using current experiments and observations. This study it is not
only allowing us to test at higher and higher energies a fundamental symmetry
of spacetime but it is also providing us with hints and perspectives about the
fundamental nature of gravity.


title: A concentration of quasars around the jet galaxy NGC1097

abstract:
  A quasar search in the region of the active galaxy NGC 1097 yielded 31
quasars in 1984. After completion of the 2dF survey in 2004 the number of
catalogued quasars just within 1 degree of the galaxy increased to 142. About
38 $\pm$ 10 of these are in excess of average background values.
  The evidence in 1984 is confirmed here by an increasing density of quasars as
one approaches NGC 1097. Quasars within 1 degree differ from the background by
being significantly brighter. There also appear two elliptical rings or arcs of
quasars at r $\sim$ 20'and 40'.


title:
Direct observation of quantum superconducting fluctuations in an
  insulating groundstate

abstract:
  We review our recent measurements of the complex AC conductivity of thin
InO_x films studied as a function of magnetic field through the nominal 2D
superconductor-insulator transition. These measurements - the first of their
type to probe nonzero frequency - reveals a significant finite frequency
superfluid stiffness well into the insulating regime. Unlike conventional
fluctuation superconductivity in which thermal fluctuations give a
superconducting response in regions of parameter space that don't exhibit long
range order, these fluctuations are temperature independent as T --> 0 and are
exhibited in samples where the resistance is large (greater than 10^6
Ohms/Square) and strongly diverging. We interpret this as the direct
observation of quantum superconducting fluctuations around an insulating ground
state. This system serves as a prototype for other insulating states of matter
that derive from superconductors.


title: Cluster structures in Oxygen isotopes

abstract:
  Cluster structure of 16O,18O and 20O is investigated by the antisymmettrized
molecular dynamics (AMD) plus generator coordinate method (GCM). We have found
the K^{\pi}=0$_2^+$ and 0$_1^-$ rotational bands of 18O that have the prominent
14C+\alpha cluster structure. Clustering systematics becomes richer in 20O. We
suggest the K^{\pi}=0$_2^+$ band that is the mixture of the 12C+\alpha+4n and
14C+6He cluster structures, and the K^{\pi}=0$_1^-$ band that has the 14C+6He
cluster structure. The K^{\pi}=0$_3^+$ and 0$_2^-$ bands that have the
prominent 16C+\alpha cluster structure are also found.


title:
Recovery of small electromagnetic inhomogeneities from boundary
  measurements in time-dependent Maxwell's equations

abstract:
  We consider for the time-dependent Maxwell's equations the inverse problem of
identifying locations and certain properties of small electromagnetic
inhomogeneities in a homogeneous background medium from dynamic measurements of
the tangential component of the magnetic field on the boundary (or a part of
the boundary) of a domain.


title:
Conditional dynamics induced by new configurations for Rydberg
  dipole-dipole interactions

abstract:
  We suggest a novel way to use strong Rydberg dipole-dipole interactions in
order to induce non-trivial conditional dynamics in individual-atom systems and
mesoscopic ensembles. Contrary to previous works, we suggest to excite atoms
into different Rydberg states, which results in a potentially richer dynamical
behaviour. Specifically, we investigate systems of individual hydrogen-like
atoms or mesoscopic ensembles excited into high-lying hydrogen-like s, p or d
states and show how to perform three-qubit conditional dynamics on the
information they contain through a proper use of dipole-dipole interaction
induced energy shifts.


title: The radio properties of type II quasars

abstract:
  Quasars (of type I) are the luminous analogs of type I Seyfert galaxies.
Within the framework of unified models of active galaxies, the population of
quasars of type II recently discovered with the Sloan Digital Sky Survey are
the luminous analogs of type II Seyfert galaxies. Since our knowledge and
understanding of the radio properties of these type II quasars are very
limited, we have performed Very Large Array observations for a sub-sample of
such sources. Our detection rate of 61% is consistent with the detection rate
for other AGN samples. We do not find a correlation between radio and [O III]
$\lambda$5007 luminosities for these sources. Although the distribution of
spectral indices is similar to that of the 3C sources, the lack of dependence
of radio luminosity on [O III] $\lambda$5007 luminosity suggests that not all
sources in the sample are genuine AGNs.


title:
Using Fast-Switching Data to Characterize Atmospheric Phase Fluctuations
  at the Submillimeter Array

abstract:
  For the submillimeter band observations, we have been routinely adopting the
calibration cycle time of 20-30 minutes, which is the same as any typical
centimeter and millimeter band observations. This cycle time, largely corrects
only the instrumental phase fluctuations and there exists residual phase
fluctuations, which are attributed to temporal and spatial atmospheric phase
fluctuations. Hence, the classical calibration cycle needs closer attention for
any future submillimeter band observations. We have therefore obtained
fast-switching test data, cycling between three nearby calibrators, using the
submillimeter array (SMA) with a cycle time of $\sim$90 sec, in order to
understand and optimize the calibration cycle suitably, thereby to achieve the
projected sensitivity, angular resolution and dynamic range for the SMA. Here,
we present the preliminary results from this study.


title:
Existence and non-existence results for a logistic-type equation on
  manifolds

abstract:
  We study the steady state solutions of a generalized logistic type equation
on a complete Riemannian manifold. We provide sufficient conditions for
existence, respectively non-existence of positive solutions, which depend on
the relative size of the coefficients and their mutual interaction with the
geometry of the manifold, which is mostly taken into account by means of
conditions on the volume growth of geodesic balls.


title: Central limit theorem, deformed exponentials and superstatistics

abstract:
  We show that there exists a very natural, superstatistics-linked extension of
the central limit theorem (CLT) to deformed exponentials (also called
q-Gaussians): This generalization favorably compares with the one provided by
S. Umarov and C. Tsallis [arXiv:cond-mat/0703533], since the latter requires a
special "q-independence" condition on the data. On the contrary, our CLT
proposal applies exactly in the usual conditions in which the classical CLT is
used. Moreover, we show that, asymptotically, the q-independence condition is
naturally induced by our version of the CLT.


title:
Nonequilibrium spin-dependent phenomena in mesoscopic
  superconductor-normal metal tunnel structures

abstract:
  We analyze the broad range of spin-dependent nonequilibrium transport
properties of hybrid systems composed of a normal region tunnel coupled to two
superconductors with exchange fields induced by the proximity to thin
ferromagnetic layers and highlight its functionalities. By calculating the
quasiparticle distribution functions in the normal region we find that they are
spin-dependent and strongly sensitive to the relative angle between exchange
fields in the two superconductors. The impact of inelastic collisions on their
properties is addressed. As a result, the electric current flowing through the
system is found to be strongly dependent on the relative angle between exchange
fields, giving rise to a huge value of magnetoresistance. Moreover, the current
presents a complete spin-polarization in a wide range of bias voltages, even in
the quasiequilibrium case. In the nonequilibrium limit we parametrize the
distributions with an ``effective`` temperature, which turns out to be strongly
spin-dependent, though quite sensitive to inelastic collisions. By tunnel
coupling the normal region to an additional superconducting electrode we show
that it is possible to implement a spin-polarized current source of both spin
species, depending on the bias voltages applied.


title: The M-estimator in a multi-phase random nonlinear model

abstract:
  This paper considers M-estimation of a nonlinear regression model with
multiple change-points occuring at unknown times. The multi-phase random design
regression model, discontinuous in each change-point, have an arbitrary error
$\epsilon$. In the case when the number of jumps is known, the M-estimator of
locations of breaks and of regression parameters are studied. These estimators
are consistent and the distribution of the regression parameter estimators is
Gaussian. The estimator of each change-point converges, with the rate $n^{-1}$,
to the smallest minimizer of the independent compound Poisson processes. The
results are valid for a large class of error distributions.


title:
Quantum simulation of interacting high-dimensional systems: the
  influence of noise

abstract:
  We consider the simulation of interacting high-dimensional systems using
pairwise interacting qubits. The main tool in this context is the generation of
effective many-body interactions, and we examine a number of different
protocols for obtaining them. These methods include the usage of higher-order
processes (commutator method), unitary conjugation or graph state encoding, as
well as teleportation based approaches. We illustrate and compare these methods
in detail and analyze the time cost for simulation. In the second part of the
article, we investigate the influence of noise on the simulation process. We
concentrate on errors in the interaction Hamiltonians and consider two generic
noise models, (i) timing errors in pairwise interactions and (ii) noisy
pairwise interactions described by Master equations of Lindblad form. We
analyze and compare the effect of noise for the different simulation methods
and propose a way to significantly reduce the influence of noise by making use
of entanglement purification together with a teleportation based protocol.


title: A simple hidden variable experiment

abstract:
  An experiment is described which proves, using single photons only, that the
standard hidden variables assumptions (commonly used to derive Bell
inequalities) are inconsistent with quantum mechanics. The analysis is very
simple and transparent. In particular, it demonstrates that a classical wave
model for quantum mechanics is not ruled out by experiments demonstrating the
violation of the traditional hidden variable assumptions.


title:
A Cross-disciplinary Framework for the Description of Contextually
  Mediated Change

abstract:
  We present a mathematical framework (referred to as Context-driven
Actualization of Potential, or CAP) for describing how entities change over
time under the influence of a context. The approach facilitates comparison of
change of state of entities studied in different disciplines. Processes are
seen to differ according to the degree of nondeterminism, and the degree to
which they are sensitive to, internalize, and depend upon a particular context.
Our analysis suggests that the dynamical evolution of a quantum entity
described by the Schrodinger equation is not fundamentally different from
change provoked by a measurement often referred to as collapse, but a limiting
case, with only one way to collapse. The biological transition to coded
replication is seen as a means of preserving structure in the fact of
context-driven change, and sextual replication as a means of increasing
potentiality thus enhancing diversity through interaction with context. The
framework sheds light on concepts like selection and fitness, reveals how
exceptional Darwinian evolution is as a means of 'change of state', and
clarifies in what sense culture, and the creative process underlying it, are
Darwinian.


title:
Number of irreducible polynomials in several variables over finite
  fields

abstract:
  We give a formula and an estimation for the number of irreducible polynomials
in two (or more) variables over a finite field.


title: Charmonium singlets, open charm and exotic hadrons

abstract:
  Caution is suggested on the comparison of the spin-singlet charmonium P-state
with the centre of gravity of triplet states, when the mass splitting is of the
order of a few MeV. The physics of new hidden-charm states X and Y is briefly
reviewed. Perspectives for producing double-charm baryons and double-charm
exotic mesons are discussed.


title: Combination quantum oscillations in canonical single-band Fermi liquids

abstract:
  Chemical potential oscillations mix individual-band frequencies of the de
Haas-van Alphen (dHvA) and Shubnikov-de Haas (SdH) magneto-oscillations in
canonical low-dimensional multi-band Fermi liquids. We predict a similar mixing
in canonical single-band Fermi liquids, which Fermi-surfaces have two or more
extremal cross-sections. Combination harmonics are analysed using a single-band
almost two-dimensional energy spectrum. We outline some experimental conditions
allowing for resolution of combination harmonics.


title:
Dijkgraaf-Witten invariants of surfaces and projective representations
  of groups

abstract:
  We compute the Dijkgraaf-Witten invariants of surfaces in terms of projective
representations of groups. As an application we prove that the complex
Dijkgraaf-Witten invariants of surfaces of positive genus are positive
integers.


title:
Electrical Neutrality and Symmetry Restoring Phase Transitions at High
  Density in a Two-Flavor Nambu-Jona-Lasinio Model

abstract:
  A general research on chiral symmetry restoring phase transitions at zero
temperature and finite chemical potentials under electrical neutrality
condition has been conducted in a Nambu-Jona-Lasinio model to describe
two-flavor normal quark matter. Depending on that $m_0/\Lambda$, the ratio of
dynamical quark mass in vacuum and the 3D momentum cutoff in the loop
integrals, is less or greater than 0.413, the phase transition will be second
or first order. A complete phase diagram of $u$ quark chemical potential versus
$m_0$ is given. With the electrical neutrality constraint, the region where
second order phase transition happens will be wider than the one without
electrical neutrality limitation. The results also show that, for the value of
$m_0/\Lambda$ from QCD phenomenology, the phase transition must be first order.


title:
Holographic spectral functions and diffusion constants for fundamental
  matter

abstract:
  The holographic dual of large-Nc super-Yang-Mills coupled to a small number
of flavours of fundamental matter, Nf << Nc, is described by Nf probe D7-branes
in the gravitational background of Nc black D3-branes. This system undergoes a
first order phase transition characterised by the `melting' of the mesons. We
study the high temperature phase in which the D7-branes extend through the
black hole horizon. In this phase, we compute the spectral function for vector,
scalar and pseudoscalar modes on the D7-brane probe. We also compute the
diffusion constant for the flavour currents.


title: Output Stream of Binding Neuron with Feedback

abstract:
  The binding neuron model is inspired by numerical simulation of
Hodgkin-Huxley-type point neuron, as well as by the leaky integrate-and-fire
model. In the binding neuron, the trace of an input is remembered for a fixed
period of time after which it disappears completely. This is in the contrast
with the above two models, where the postsynaptic potentials decay
exponentially and can be forgotten only after triggering. The finiteness of
memory in the binding neuron allows one to construct fast recurrent networks
for computer modeling. Recently, the finiteness is utilized for exact
mathematical description of the output stochastic process if the binding neuron
is driven with the Poissonian input stream. In this paper, the simplest
networking is considered for binding neuron. Namely, it is expected that every
output spike of single neuron is immediately fed into its input. For this
construction, externally fed with Poissonian stream, the output stream is
characterized in terms of interspike interval probability density distribution
if the binding neuron has threshold 2. For higher thresholds, the distribution
is calculated numerically. The distributions are compared with those found for
binding neuron without feedback, and for leaky integrator. Sample distributions
for leaky integrator with feedback are calculated numerically as well. It is
oncluded that even the simplest networking can radically alter spikng
statistics. Information condensation at the level of single neuron is
discussed.


title: Cavity solitons in bidirectional lasers

abstract:
  We show theoretically that a broad area bidirectional laser with slightly
different cavity losses for the two counterpropagating fields sustains cavity
solitons (CSs). These structures are complementary, i.e., there is a bright
(dark) CS in the field with more (less) losses. Interestingly, the CSs can be
written/erased by injecting suitable pulses in any of the two
counterpropagating fields.


title: (An)isotropy of the Hubble diagram: comparing hemispheres

abstract:
  We test the isotropy of the Hubble diagram. At small redshifts, this is
possible without assumptions on the cosmic inventory and provides a fundamental
test of the cosmological principle. At higher redshift we check for the
self-consistency of the LambdaCDM model. At small redshifts, we use public
supernovae (SNe) Ia data to determine the deceleration parameter q_0 and the SN
calibration on opposite hemispheres. For the complete data sets we fit Omega_M
and the SN calibration on opposite hemispheres. A statistically significant
anisotropy of the Hubble diagram at redshifts z < 0.2 is discovered (> 95%
C.L.). While data from the North Galactic hemisphere favour the accelerated
expansion of the Universe, data from the South Galactic hemisphere are not
conclusive. The hemispheric asymmetry is maximal toward a direction close to
the equatorial poles. The discrepancy between the equatorial North and South
hemispheres shows up in the SN calibration. For the LambdaCDM model fitted to
all available SNe, we find the same asymmetry. The alignment of discrepancies
between hemispheric Hubble diagrams with the equatorial frame seems to point
toward a systematic error in the SN search, observation, analysis or data
reduction. We also find that our model independent test cannot exclude the case
of the deceleration of the expansion at a statistically significant level.


title:
A CLT for Information-theoretic statistics of Gram random matrices with
  a given variance profile

abstract:
  Consider a $N\times n$ random matrix $Y_n=(Y_{ij}^{n})$ where the entries are
given by $$ Y_{ij}^{n}=\frac{\sigma_{ij}(n)}{\sqrt{n}} X_{ij}^{n} $$ the
$X_{ij}^{n}$ being centered, independent and identically distributed random
variables with unit variance and $(\sigma_{ij}(n); 1\le i\le N, 1\le j\le n)$
being an array of numbers we shall refer to as a variance profile. We study in
this article the fluctuations of the random variable $$ \log\det(Y_n Y_n^* +
\rho I_N) $$ where $Y^*$ is the Hermitian adjoint of $Y$ and $\rho > 0$ is an
additional parameter. We prove that when centered and properly rescaled, this
random variable satisfies a Central Limit Theorem (CLT) and has a Gaussian
limit whose parameters are identified. A complete description of the scaling
parameter is given; in particular it is shown that an additional term appears
in this parameter in the case where the 4$^\textrm{th}$ moment of the
$X_{ij}$'s differs from the 4$^{\textrm{th}}$ moment of a Gaussian random
variable. Such a CLT is of interest in the field of wireless communications.


title: Extremal functions for the sharp $L^2-$ Nash inequality

abstract:
  We give geometrical conditions under which there exist extremal functions for
the sharp $L^2$-Nash inequality.


title:
Kullback-Leibler distance as a measure of the information filtered from
  multivariate data

abstract:
  We show that the Kullback-Leibler distance is a good measure of the
statistical uncertainty of correlation matrices estimated by using a finite set
of data. For correlation matrices of multivariate Gaussian variables we
analytically determine the expected values of the Kullback-Leibler distance of
a sample correlation matrix from a reference model and we show that the
expected values are known also when the specific model is unknown. We propose
to make use of the Kullback-Leibler distance to estimate the information
extracted from a correlation matrix by correlation filtering procedures. We
also show how to use this distance to measure the stability of filtering
procedures with respect to statistical uncertainty. We explain the
effectiveness of our method by comparing four filtering procedures, two of them
being based on spectral analysis and the other two on hierarchical clustering.
We compare these techniques as applied both to simulations of factor models and
empirical data. We investigate the ability of these filtering procedures in
recovering the correlation matrix of models from simulations. We discuss such
an ability in terms of both the heterogeneity of model parameters and the
length of data series. We also show that the two spectral techniques are
typically more informative about the sample correlation matrix than techniques
based on hierarchical clustering, whereas the latter are more stable with
respect to statistical uncertainty.


title: Monge-Ampere measures on pluripolar sets

abstract:
  In this article we solve the complex Monge-Ampere equation for measures with
large singular part. This result generalizes classical results by Demailly,
Lelong and Lempert a.o., who considered singular parts carried on discrete
sets. By using our result we obtain a generalization of Kolodziej's subsolution
theorem. More precisely, we prove that if a non-negative Borel measure is
dominated by a complex Monge-Ampere measure, then it is a complex Monge-Ampere
measure.


title: On the origin of the $\lambda$-transition in liquid Sulphur

abstract:
  Developing a novel experimental technique, we applied photon correlation
spectroscopy using infrared radiation in liquid Sulphur around $T_\lambda$,
i.e. in the temperature range where an abrupt increase in viscosity by four
orders of magnitude is observed upon heating within few degrees. This allowed
us - overcoming photo-induced and absorption effects at visible wavelengths -
to reveal a chain relaxation process with characteristic time in the ms range.
These results do rehabilitate the validity of the Maxwell relation in Sulphur
from an apparent failure, allowing rationalizing the mechanical and
thermodynamic behavior of this system within a viscoelastic scenario.


title:
Persistent pods of the tree Acacia caven: a natural refuge for diverse
  insects including Bruchid beetles and the parasitoids Trichogrammatidae,
  Pteromalidae and Eulophidae

abstract:
  The persistent pods of the tree, Acacia caven, that do not fall from the tree
provide opportunities for the appearance of a diverse group of insects the
following season. Such pods collected during the spring of 1999 in Chile were
indehiscent with highly sclerified pod walls. In contrast, persistent pods
collected in Uruguay after a wet winter and spring (2002) were partially
dehiscent, inducing the deterioration of the woody pods, and consequently
exposing the seeds. These persistent pods are a natural refuge for insect
species, namely two bruchid beetles (Pseudopachymeria spinipes, Stator
furcatus), one scolytidae (Dendroctonus sp), lepidopterous larvae, ant colonies
(Camponotus sp),one species of oophagous parasitoid (Uscana espinae group
senex), the gregarious larval-pupae parasitoid Monoksa dorsiplana
(Pteromalidae) and two species of Horismenus spp. (Eulophidae). The patriline
of M. dorsiplana is frequently formed by 1 son +7 daughters.


title: The geometrical quantity in damped wave equations on a square

abstract:
  The energy in a square membrane $\Omega$ subject to constant viscous damping
on a subset $\omega\subset \Omega$ decays exponentially in time as soon as
$\omega$ satisfies a geometrical condition known as the "Bardos-Lebeau-Rauch"
condition. The rate $\tau(\omega)$ of this decay satisfies $\tau(\omega)= 2
\min(-\mu(\omega), g(\omega))$ (see Lebeau [Math. Phys. Stud. 19 (1996)
73-109]). Here $\mu(\omega)$ denotes the spectral abscissa of the damped wave
equation operator and $g(\omega)$ is a number called the geometrical quantity
of $\omega$ and defined as follows. A ray in $\Omega$ is the trajectory
generated by the free motion of a mass-point in $\Omega$ subject to elastic
reflections on the boundary. These reflections obey the law of geometrical
optics. The geometrical quantity $g(\omega)$ is then defined as the upper limit
(large time asymptotics) of the average trajectory length. We give here an
algorithm to compute explicitly $g(\omega)$ when $\omega$ is a finite union of
squares.


title: Teleportation of atomic states via position measurements

abstract:
  We present a scheme for conditionally teleporting an unknown atomic state in
cavity QED, which requires two atoms and one cavity mode. The translational
degrees of freedom of the atoms are taken into account using the optical
Stern-Gerlach model. We show that successful teleportation with probability 1/2
can be achieved through local measurements of the cavity photon number and
atomic positions. Neither direct projection onto highly entangled states nor
holonomous interaction-time constraints are required.


title: Entropy signature of the running cosmological constant

abstract:
  Renormalization group (RG) improved cosmologies based upon a RG trajectory of
Quantum Einstein Gravity (QEG) with realistic parameter values are investigated
using a system of cosmological evolution equations which allows for an
unrestricted energy exchange between the vacuum and the matter sector. It is
demonstrated that the scale dependence of the gravitational parameters, the
cosmological constant in particular, leads to an entropy production in the
matter system. The picture emerges that the Universe started out from a state
of vanishing entropy, and that the radiation entropy observed today is
essentially due to the coarse graining (RG flow) in the quantum gravity sector
which is related to the expansion of the Universe. Furthermore, the RG improved
field equations are shown to possess solutions with an epoch of power law
inflation immediately after the initial singularity. The inflation is driven by
the cosmological constant and ends automatically once the RG running has
reduced the vacuum energy to the level of the matter energy density.


title:
The 't Hooft loop in the Hamiltonian approach to Yang-Mills theory in
  Coulomb gauge

abstract:
  The spatial 't Hooft loop, which is a disorder parameter dual to the temporal
Wilson loop, is calculated using the nonperturbative Yang-Mills vacuum wave
functional determined previously by a variational solution of the Yang-Mills
Schroedinger equation in Coulomb gauge. It is shown, that this wave functional
yields indeed a perimeter law for large spatial 't Hooft loops signaling
confinement.


title: Charge inhomogeneities due to smooth ripples in graphene sheets

abstract:
  We study the effect of the curved ripples observed in the free standing
graphene samples on the electronic structure of the system. We model the
ripples as smooth curved bumps and compute the Green's function of the Dirac
fermions in the curved surface. Curved regions modify the Fermi velocity that
becomes a function of the point on the graphene surface and induce energy
dependent oscillations in the local density of states around the position of
the bump. The corrections are estimated to be of a few percent of the flat
density at the typical energies explored in local probes such as scanning
tunnel microscopy that should be able to observe the predicted correlation of
the morphology with the electronics. We discuss the connection of the present
work with the recent observation of charge anisotropy in graphene and propose
that it can be used as an experimental test of the curvature effects.


title:
Spin Effect on the Resonant Tunneling Characteristics of a
  Double-Barrier Heterostructures Under Longitudinal Stresses

abstract:
  Theoretical research on electronic properties in mesoscopic condensed matter
systems has focused primarily on the electron charge freedom degrees, while its
corresponding spin freedom degrees have not yet received the same attention.
Nevertheless nowadays there has been an increment in the number of electron
spin-related experiments showing unique possibilities for finding novel
mechanisms of information processing and transmission, opening ample fields of
opportunities in the theoretical developed of new models. In this spirit we
have calculated the resonant tunneling characteristics curves in double-barrier
heterostructures of GaAs-Ga1-x AlxAs under external stress and considering two
charges with spin half. The resonant tunneling study has been carried out by
means of the diagrammatic techniques for non equilibrium processes following
the model proposed by Keldysh also a simple one-band tight-binding Hamiltonian
is adopted in the theoretical framework. We have compared our results of the
spin-tunneling with previous ones reported in literature.


title: Sterile neutrino production in models with low reheating temperatures

abstract:
  By numerically solving the appropriate Boltzmann equations, we study the
production of sterile neutrinos in models with low reheating temperatures. We
take into account the production in oscillations as well as in direct decays
and compute the sterile neutrino primordial spectrum, the effective number of
neutrino species, and the sterile neutrino contribution to the mass density of
the Universe as a function of the mixing and the reheating parameters. It is
shown that sterile neutrinos with non-negligible mixing angles do not
necessarily lead to $N_\nu\sim 4$ and that sterile neutrinos may have the right
relic density to explain the dark matter of the Universe. If dark matter
consists of sterile neutrinos produced in oscillations, X-rays measurements set
a strong limit on the reheating temperature, $\tr\gtrsim 7\mev$. We also point
out that the direct decay opens up a new production mechanism for sterile
neutrino dark matter where cosmological constraints can be satisfied.


title: Lattice Refining Loop Quantum Cosmology and Inflation

abstract:
  We study the importance of lattice refinement in achieving a successful
inflationary era. We solve, in the continuum limit, the second order difference
equation governing the quantum evolution in loop quantun cosmology, assuming
both a fixed and a dynamically varying lattice in a suitable refinement model.
We thus impose a constraint on the potential of a scalar field, so that the
continuum approximation is not broken. Considering that such a scalar field
could play the role of the inflaton, we obtain a second constraint on the
inflationary potential so that there is consistency with the CMB data on large
angular scales. For a $m^2\phi^2/2$ inflationary model, we combine the two
constraints on the inflaton potential to impose an upper limit on $m$, which is
severely fine-tuned in the case of a fixed lattice. We thus conclude that
lattice refinement is necessary to achieve a natural inflationary model.


title: Weak measurement of quantum dot spin qubits

abstract:
  The theory of weak quantum measurements is developed for quantum dot spin
qubits. Building on recent experiments, we propose a control cycle to prepare,
manipulate, weakly measure, and perform quantum state tomography. This is
accomplished using a combination of the physics of electron spin resonance,
spin blockade, and Coulomb blockade, resulting in a charge transport process.
We investigate the influence of the surrounding nuclear spin environment, and
find a regime where this environment significantly simplifies the dynamics of
the weak measurement process, making this theoretical proposal realistic with
existing experimental technology. We further consider spin-echo refocusing to
combat dephasing, as well as discuss a realization of "quantum undemolition",
whereby the effects of quantum state disturbance are undone.


title: Switching of optical vortices in nonlinear annular couplers

abstract:
  We suggest an annular waveguide coupler for switching the angular momentum of
light. We study linear and nonlinear coupling of both power and momentum of an
optical vortex beam launched into one of the ring cores, and demonstrate that
the switching takes place well below the collapse threshold. The switching is
more effective for the inner-ring excitation since it triggers more sharply and
for the lower power enough to avoid the beam azimuthal instability.


title:
The structure on the real field generated by the standard part map on an
  o-minimal expansion of a real closed field

abstract:
  Let R be a sufficiently saturated o-minimal expansion of a real closed field,
let O be the convex hull of the rationals in R, and let st: O^n \to
\mathbb{R}^n be the standard part map. For X \subseteq R^n define st(X):=st(X
\cap O^n). We let \mathbb{R}_{\ind} be the structure with underlying set
\mathbb{R} and expanded by all sets of the form st(X), where X \subseteq R^{n}
is definable in R and n=1,2,.... We show that the subsets of \mathbb{R}^n that
are definable in \mathbb{R}_{\ind} are exactly the finite unions of sets of the
form st(X) \setminus st(Y), where X,Y \subseteq R^n are definable in R. A
consequence of the proof is a partial answer to a question by Hrushovski,
Peterzil and Pillay about the existence of measures with certain invariance
properties on the lattice of bounded definable sets in R^n.


title:
Regge approach to charged-pion photoproduction at invariant energies
  above 2 GeV

abstract:
  A Regge model with absorptive corrections is employed in a global analysis of
the world data on positive and negative pion photoproduction for photon
energies from 3 to 8 GeV. In this region resonance contributions are expected
to be negligible so that the available experimental information on differential
cross sections and single polarization observables at -t \leq 2 GeV^2 allows us
to determine the non-resonant part of the reaction amplitude reliably. The
model amplitude is then used to predict observables for photon energies below 3
GeV. Differences between our predictions and data in this energy region are
systematically examined as possible signals for the presence of excited
baryons. We find that the data available for the polarized photon asymmetry
show promising resonance signatures at invariant energies around 2 GeV. With
regard to differential cross sections the analysis of negative pion
photoproduction data, obtained recently at JLab, indicates likewise the
presence of resonance structures around 2 GeV


title: Pressure induced Insulator-Metal transition in LaMnO$_3$

abstract:
  The recent observation of a insulator to metal transition (IMT) [I. Loa et
al, PRL 87, 125501 (2001)] in pure LaMnO$_3$ at 32 GPa and room temperature,
well above the Neel temperature (145 K) and below the Jahn-Teller transition
temperature (780 K), opens the way to a study of the role of the orbital
degrees of freedom on the electronic structure in a stoichiometric material. In
this paper we focus our attention in the orbital aspects of the insulator to
metal transition. We use a model Hamiltonian for the $e_g$ orbitals of Mn that
includes the on site Coulomb repulsion $U$, the hopping $t$, and its dependence
with pressure. In order to include in an appropriate way the strong
correlations induced by the dominant electron-electron interactions we
introduce auxiliary fields (Slave Bosons,SB) to the description of the low
energy states. We use a O-Mn distance ($d$) dependence of $t$ and the
pressure-$d$ relation from the experimental data to describe the evolution of
the electronic structure with pressure. Our results confirm and make
transparent the conclusion reached in previous ab-initio calculations: the
inclusion of the Coulomb energy is necessary and constitutes an important
factor enhancing the orbital polarization in these compounds.


title:
Excluded volume, local structural cooperativity,and the polymer physics
  of protein folding rates

abstract:
  A coarse-grained variational model is used to investigate the polymer
dynamics of barrier crossing for a diverse set of two-state folding proteins.
The model gives reliable folding rate predictions provided excluded volume
terms that induce minor structural cooperativity are included in the
interaction potential. In general, the cooperative folding routes have sharper
interfaces between folded and unfolded regions of the folding nucleus and
higher free energy barriers. The calculated free energy barriers are strongly
correlated with native topology as characterized by contact order. Increasing
the rigidity of the folding nucleus changes the local structure of the
transition state ensemble non-uniformly across the set of protein studied.
Neverthless, the calculated prefactors k0 are found to be relatively uniform
across the protein set, with variation in 1/k0 less than a factor of five. This
direct calculation justifies the common assumption that the prefactor is
roughly the same for all small two-state folding proteins. Using the barrier
heights obtained from the model and the best fit monomer relaxation time 30ns,
we find that 1/k0 (1-5)us (with average 1/k0 4us). This model can be extended
to study subtle aspects of folding such as the variation of the folding rate
with stability or solvent viscosity, and the onset of downhill folding.


title: Dark Matter from the Inert Doublet Model

abstract:
  The Inert Doublet Model is an extension of the Standard Model including one
extra ``Inert scalar doublet'' and an exact $Z_2$ symmetry. The ``Inert
scalar'' provides a new candidate for dark matter. We present a systematic
analysis of the dark matter abundance assuming the standard freeze-out
mechanism and investigate the potentialities for direct and gamma indirect
detection. We show that the dark matter candidate saturates the WMAP dark
matter density in two rather separate mass ranges, one between 40 and 80 GeV,
the other one over 400 GeV. We also show that the model should be within the
range of future experiments, like GLAST and EDELWEISS II or ZEPLIN.


title: Modelling Quasicrystals

abstract:
  A new kind of aperiodic tiling is introduced. It is shown to underlie a
structure obtained as a superposition of waves with incommensurate periods. Its
connections to other other tilings and quasicrystals are discussed.


title:
Cascade of Gregory-Laflamme Transitions and U(1) Breakdown in Super
  Yang-Mills

abstract:
  In this paper we consider black p-branes on square torus. We find an
indication of a cascade of Gregory-Laflamme transitions between black p-brane
and (p-1)-brane. Through AdS/CFT correspondence, these transitions are related
to the breakdown of the U(1) symmetry in super Yang-Mills on torus. We argue a
relationship between the cascade and recent Monte-Carlo data.


title: Diagnostic tools for 3D unstructured oceanographic data

abstract:
  Most ocean models in current use are built upon structured meshes. It follows
that most existing tools for extracting diagnostic quantities (volume and
surface integrals, for example) from ocean model output are constructed using
techniques and software tools which assume structured meshes. The greater
complexity inherent in unstructured meshes (especially fully unstructured grids
which are unstructured in the vertical as well as the horizontal direction) has
left some oceanographers, accustomed to traditional methods, unclear on how to
calculate diagnostics on these meshes. In this paper we show that tools for
extracting diagnostic data from the new generation of unstructured ocean models
can be constructed with relative ease using open source software. Higher level
languages such as Python, in conjunction with packages such as NumPy, SciPy,
VTK and MayaVi, provide many of the high-level primitives needed to perform 3D
visualisation and evaluate diagnostic quantities, e.g. density fluxes. We
demonstrate this in the particular case of calculating flux of vector fields
through isosurfaces, using flow data obtained from the unstructured mesh finite
element ocean code ICOM, however this tool can be applied to model output from
any unstructured grid ocean code.


title:
Quantum Properties and Gravitational Field of a System with Oscillations
  in Time

abstract:
  We study the quantum properties and gravitational field of a system that has
oscillations in time. Treating time as a dynamical variable, we first construct
a wave with 4-vector amplitude that has matters vibrating in space and time. By
analyzing its Hamiltonian density equation, we find that such system shall be
treated as a quantized field. This quantized real scalar field obeys the
Klein-Gordon equation and has properties resemble a zero spin bosonic field. In
addition, the particle observed has oscillation in proper time. By neglecting
all quantum effects and assuming the particle as a classical object that can
remain stationary in space, we show that the spacetime geometry around the
proper time oscillation has properties similar to the Schwarzschild
gravitational field of a point mass in relativity.


title: VLBI observations of seven BL Lac objects from RGB sample

abstract:
  We present EVN observations of seven BL Lac objects selected from the RGB
sample. To investigate the intrinsic radiation property of BL Lac objects, we
estimated the Doppler factor with the VLA or MERLIN core and the total 408 MHz
luminosity for a sample of 170 BL Lac objects. The intrinsic (comoving)
synchrotron peak frequency was then calculated by using the estimated Doppler
factor. Assuming a Lorentz factor of 5, the viewing angle of jets was
constrained. The high-resolution VLBI images of seven sources all show a
core-jet structure. We estimated the proper motions of three sources with the
VLBI archive data, and find that the apparent speed increases with the distance
of components to the core for all of them. In our BL Lacs sample, the Doppler
factor of LBLs is systematically larger than that of IBLs and HBLs. We find a
significant anti-correlation between the total 408 MHz luminosity and the
intrinsic synchrotron peak frequency. However, the scatter is much larger than
for the blazar sequence. Moreover, we find a significant positive correlation
between the viewing angle and the intrinsic synchrotron peak frequency. The BL
Lac objects show a continuous distribution on the viewing angle. While LBLs
have a smaller viewing angle than that of IBLs and HBLs, IBLs are comparable to
HBLs. We conclude that the intrinsic synchrotron peak frequency is not only
related to the intrinsic radio power (though with a large scatter), but also to
the viewing angle for the present sample.


title:
On factorizations of smooth nonnegative matrix-values functions and on
  smooth functions with values in polyhedra

abstract:
  We discuss the possibility to represent smooth nonnegative matrix-valued
functions as finite linear combinations of fixed matrices with positive
real-valued coefficients whose square roots are Lipschitz continuous. This
issue is reduced to a similar problem for smooth functions with values in a
polyhedron.


title:
Particle-in-cell simulations of fast collisionless reconnection in
  gamma-ray burst outflows

abstract:
  We present preliminary results of particle-in-cell simulations of
collisionless magnetic reconnection for conditions that apply to magnetically
dominated pair plasma jets such as those in gamma-ray bursts. We find similar
behaviour to previous authors but with reduced reconnection efficiency. This
results because we include the full electromagnetic field dynamically and allow
electric field fluctuations to grow. Although weak, these fluctuations impede
early x-point formation by periodically decelerating and even reversing the
inflow.


title:
Comparing Classical Pathways and Modern Networks: Towards the
  Development of an Edge Ontology

abstract:
  Pathways are integral to systems biology. Their classical representation has
proven useful but is inconsistent in the meaning assigned to each arrow (or
edge) and inadvertently implies the isolation of one pathway from another.
Conversely, modern high-throughput experiments give rise to standardized
networks facilitating topological calculations. Combining these perspectives,
we can embed classical pathways within large-scale networks and thus
demonstrate the crosstalk between them. As more diverse types of
high-throughput data become available, we can effectively merge both
perspectives, embedding pathways simultaneously in multiple networks. However,
the original problem still remains - the current edge representation is
inadequate to accurately convey all the information in pathways. Therefore, we
suggest that a standardized, well-defined, edge ontology is necessary and
propose a prototype here, as a starting point for reaching this goal.


title: Equivalence of operations with respect to discriminator clones

abstract:
  For each clone C on a set A there is an associated equivalence relation,
called C-equivalence, on the set of all operations on A, which relates two
operations iff each one is a substitution instance of the other using
operations from C. In this paper we prove that if C is a discriminator clone on
a finite set, then there are only finitely many C-equivalence classes.
Moreover, we show that the smallest discriminator clone is minimal with respect
to this finiteness property. For discriminator clones of Boolean functions we
explicitly describe the associated equivalence relations.


title:
Atomic force microscopy (AFM) study of thick lamellar stacks of
  phospholipid bilayers

abstract:
  We report an Atomic Force Microscopy (AFM) study on thick multi lamellar
stacks of approx. 10 mum thickness (about 1500 stacked membranes) of DMPC
(1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine) deposited on silicon wafers.
These thick stacks could be stabilized for measurements under excess water or
solution. From force curves we determine the compressional modulus B and the
rupture force F_r of the bilayers in the gel (ripple), the fluid phase and in
the range of critical swelling close to the main transition. AFM allows to
measure the compressional modulus of stacked membrane systems and values for B
compare well to values reported in the literature. We observe pronounced
ripples on the top layer in the Pbeta' (ripple) phase and find an increasing
ripple period Lambda_r when approaching the temperature of the main phase
transition into the fluid Lalpha phase at about 24 C. Metastable ripples with
2Lambda_r are observed. Lambda_r also increases with increasing osmotic
pressure, i.e., for different concentrations of polyethylene glycol (PEG).


title:
Prior entanglement between senders enables perfect quantum network
  coding with modification

abstract:
  We find a protocol transmitting two quantum states crossly in the butterfly
network only with prior entanglement between two senders. This protocol
requires only one qubit transmission or two classical bits transmission in each
channel in the butterfly network. It is also proved that it is impossible
without prior entanglement. More precisely, an upper bound of average fidelity
is given in the butterfly network when prior entanglement is not allowed.


title:
Reply to Comment on "Dynamical corrections to the DFT-LDA electron
  conductance in nanoscale systems"

abstract:
  We reply to the comment by Jung, Bokes, and Godby (arXiv:0706.0140) on our
paper Phys. Rev. Lett. 94, 186810 (2005). We show that the results in their
comment should not be taken as an indication that the viscosity corrections to
the conductance of real nanoscale structures are small. A more accurate
treatment of the density and current density distribution and of the electronic
correlations may yield much larger corrections in realistic systems.


title: Approximate Killing Vectors on S^2

abstract:
  We present a new method for computing the best approximation to a Killing
vector on closed 2-surfaces that are topologically S^2. When solutions of
Killing's equation do not exist, this method is shown to yield results superior
to those produced by existing methods. In addition, this method appears to
provide a new tool for studying the horizon geometry of distorted black holes.


title: Leptogenesis With Many Neutrinos

abstract:
  We consider leptogenesis in scenarios with many neutrino singlets. We find
that the lower bound for the reheating temperature can be significantly relaxed
with respect to the hierarchical three neutrino case. We further argue that the
upper bound for the neutrino mass scale from leptogenesis gets significantly
lifted in these scenarios. As a specific realization, we then discuss an
extra-dimensional model, where the large number of neutrinos is provided by
Kaluza-Klein excitations.


title: A New Proof of the New Intersection Theorem

abstract:
  In 1987 Roberts completed the proof of the New Intersection Theorem (NIT) by
settling the mixed characteristic case using local Chern characters, as
developed by Fulton and also by Roberts. His proof has been the only one
recorded of the NIT in mixed characteristic.
  This paper gives a new proof of this theorem, one which mostly parallels
Roberts' original proof, but avoids the use of local Chern characters. Instead,
the proof here uses Adams operations on K-theory with supports as developed by
Gillet-Soule.


title: A non commutative sewing lemma

abstract:
  In a preceding paper [E.J.ofProb.34,860-892,(2006)], we proved a sewing lemma
which was a key result for the study of Holder continuous functions. In this
paper we give a non-commutative version of this lemma with some applications.


title:
Universal quantum computation in decoherence-free subspaces with hot
  trapped-ions

abstract:
  We consider interactions that generate a universal set of quantum gates on
logical qubits encoded in a collective-dephasing-free subspace, and discuss
their implementations with trapped ions. This allows for the removal of the
by-far largest source of decoherence in current trapped-ion experiments,
collective dephasing. In addition, an explicit parametrization of all two-body
Hamiltonians able to generate such gates without the system's state ever
exiting the protected subspace is provided.


title: Asymptotic results on the length of coalescent trees

abstract:
  We give the asymptotic distribution of the length of partial coalescent trees
for Beta and related coalescents. This allows us to give the asymptotic
distribution of the number of (neutral) mutations in the partial tree. This is
a first step to study the asymptotic distribution of a natural estimator of DNA
mutation rate for species with large families.


title: On initial conditions for inflationary and bouncing cosmologies

abstract:
  We consider the question of deriving initial conditions for scalar fields in
driving both an early and late quintessence phase. The dark energy field
presents an unresolved uniformity problem. Further difficulties with initial
conditions for assisted, kinetic and phantom inflation are presented. We review
the use of the canonical measure and find the negative conclusions of Gibbons
and Hawking can be allayed by means of a reasonable quantum cosmological input.
We remark upon some attempts at incorporating inflationary schemes into cyclic
and bouncing models.


title: On a class number formula for real quadratic number fields

abstract:
  For an even Dirichlet character psi, we obtain a formula for L(1,psi) in
terms of a sum of Dirichlet L-series evaluated at s=2 and s=3 and a rapidly
convergent numerical series involving the central binomial coefficients. We
then derive a class number formula for real quadratic number fields by taking
L(s,psi) to be the quadratic L-series associated with these fields.


title:
No-ghost theorem for the fourth-order derivative Pais-Uhlenbeck
  oscillator model

abstract:
  Contrary to common belief, it is shown that theories whose field equations
are higher than second order in derivatives need not be stricken with ghosts.
In particular, the prototypical fourth-order derivative Pais-Uhlenbeck
oscillator model is shown to be free of states of negative energy or negative
norm. When correctly formulated (as a $\cP\cT$ symmetric theory), the theory
determines its own Hilbert space and associated positive-definite inner
product. In this Hilbert space the model is found to be a fully acceptable
quantum-mechanical theory that exhibits unitary time evolution.


title:
Dark matter halo abundances, clustering and assembly histories at high
  redshift

abstract:
  We use a suite of high-resolution N-body simulations to study the properties,
abundance and clustering of high mass halos at high redshift, including their
mass assembly histories and mergers. We find that the analytic form which best
fits the abundance of halos depends sensitively on the assumed definition of
halo mass, with common definitions of halo mass differing by a factor of two
for these low concentration, massive halos. A significant number of massive
halos are undergoing rapid mass accretion, with major merger activity being
common. We compare the mergers and mass accretion histories to the extended
Press-Schechter formalism.
  We consider how major merger induced star formation or black hole accretion
may change the distribution of photon production from collapsed halos, and
hence reionization, using some simplified examples. In all of these, the photon
distribution for a halo of a given mass acquires a large scatter. If rare, high
mass halos contribute significantly to the photon production rates, the scatter
in photon production rate can translate into additional scatter in the sizes of
ionized bubbles.


title:
First Measurement of a Rapid Increase in the AGN Fraction in
  High-Redshift Clusters of Galaxies

abstract:
  We present the first measurement of the AGN fraction in high-redshift
clusters of galaxies (z~0.6) with spectroscopy of one cluster and archival data
for three additional clusters. We identify 8 AGN in all four of these clusters
from the Chandra data, which are sensitive to AGN with hard X-ray (2-10keV)
luminosity L_{X,H} > 10^43 erg/s in host galaxies more luminous than a rest
frame M_R < -20 mag. This stands in sharp contrast to the one AGN with L_{X,H}
> 10^43 erg/s we discovered in our earlier study of eight low-redshift clusters
with z=0.06-0.31 (average z~0.2). Three of the four high-redshift cluster
datasets are sensitive to nearly L_{X,H} > 10^42 erg/s and we identify seven
AGN above this luminosity limit, compared to two in eight, low-redshift
clusters. Based on membership estimates for each cluster, we determine that the
AGN fraction at z~0.6 is f_A(L_X>10^42;M_R<-20) = 0.028 (+0.019/-0.012) and
f_A(L_X>10^43;M_R<-20) = 0.020 (+0.012/-0.008). These values are approximately
a factor of 20 greater than the AGN fractions in lower-redshift (average z~0.2)
clusters of galaxies and represent a substantial increase over the factors of
1.5 and 3.3 increase, respectively, in the measured space density evolution of
the hard X-ray luminosity function over this redshift range. Potential
systematic errors would only increase the significance of our result. The
cluster AGN fraction increases more rapidly with redshift than the field and
the increase in cluster AGN indicates the presence of an AGN Butcher-Oemler
Effect.


title:
On the morphologies, gas fractions, and star formation rates of small
  galaxies

abstract:
  We use a series of N-body/smoothed particle hydrodynamics simulations and
analytic arguments to show that the presence of an effective temperature floor
in the interstellar medium at T_F ~ 10^4 K naturally explains the tendency for
low-mass galaxies to be more spheroidal, more gas rich, and less efficient in
converting baryons into stars than larger galaxies. The trend arises because
gas pressure support becomes important compared to angular momentum support in
small dark matter haloes. We suggest that dwarf galaxies with rotational
velocities ~ 40 km/s do not originate as thin discs, but rather are born as
thick, puffy systems. If accreted on to larger haloes, tenuous dwarfs of this
kind will be more susceptible to gas loss or tidal transformation than
scaled-down versions of larger spirals. For a constant temperature floor,
pressure support becomes less important in large haloes, and this produces a
tendency for massive isolated galaxies to have thinner discs and more efficient
star formation than their less massive counterparts, as observed.


title: Red Sequence Cluster Finding in the Millennium Simulation

abstract:
  We investigate halo mass selection properties of red-sequence cluster finders
using galaxy populations of the Millennium Simulation (MS). A clear red
sequence exists for MS galaxies in massive halos at redshifts z < 1, and we use
this knowledge to inform a cluster-finding algorithm applied to 500 Mpc/h
projections of the simulated volume. At low redshift (z=0.4), we find that 90%
of the clusters found have galaxy membership dominated by a single, real-space
halo, and that 10% are blended systems for which no single halo contributes a
majority of a cluster's membership. At z=1, the fraction of blends increases to
22%, as weaker redshift evolution in observed color extends the comoving length
probed by a fixed range of color. Other factors contributing to the increased
blending at high-z include broadening of the red sequence and confusion from a
larger number of intermediate mass halos hosting bright red galaxies of
magnitude similar to those in higher mass halos. Our method produces catalogs
of cluster candidates whose halo mass selection function, p(M|\Ngal,z), is
characterized by a bimodal log-normal model with a dominant component that
reproduces well the real-space distribution, and a redshift-dependent tail that
is broader and displaced by a factor ~2 lower in mass. We discuss implications
for X-ray properties of optically selected clusters and offer ideas for
improving both mock catalogs and cluster-finding in future surveys.


title: Breakdown of the adiabatic limit in low dimensional gapless systems

abstract:
  It is generally believed that a generic system can be reversibly transformed
from one state into another by sufficiently slow change of parameters. A
standard argument favoring this assertion is based on a possibility to expand
the energy or the entropy of the system into the Taylor series in the ramp
speed. Here we show that this argumentation is only valid in high enough
dimensions and can break down in low-dimensional gapless systems. We identify
three generic regimes of a system response to a slow ramp: (A) mean-field, (B)
non-analytic, and (C) non-adiabatic. In the last regime the limits of the ramp
speed going to zero and the system size going to infinity do not commute and
the adiabatic process does not exist in the thermodynamic limit. We support our
results by numerical simulations. Our findings can be relevant to
condensed-matter, atomic physics, quantum computing, quantum optics, cosmology
and others.

categories: cond-mat.stat-mech cond-mat.dis-nn hep-th quant-ph


title: Energy disturbances due to a moving quark from gauge-string duality

abstract:
  Using AdS/CFT, we calculate the energy density of a quark moving through a
thermal state of N=4 super-Yang-Mills theory. Relying on previous work for
momentum-space representations as well as asymptotic behaviors, we Fourier
transform to position space and exhibit a sonic boom at a speed larger than the
speed of sound. Nontrivial structure is found at small length scales,
confirming earlier analytical work by the authors.


title:
Visualizing pair formation on the atomic scale in the high-Tc
  superconductor Bi2Sr2CaCu2O8+d

abstract:
  Pairing of electrons in conventional superconductors occurs at the
superconducting transition temperature Tc, creating an energy gap D in the
electronic density of states (DOS). In the high-Tc superconductors, a partial
gap in the DOS exists for a range of temperatures above Tc. A key question is
whether the gap in the DOS above Tc is associated with pairing, and what
determines the temperature at which incoherent pairs form. Here we report the
first spatially resolved measurements of gap formation in a high-Tc
superconductor, measured on Bi2Sr2CaCu2O8+d samples with different Tc values
(hole concentration of 0.12 to 0.22) using scanning tunnelling microscopy. Over
a wide range of doping from 0.16 to 0.22 we find that pairing gaps nucleate in
nanoscale regions above Tc. These regions proliferate as the temperature is
lowered, resulting in a spatial distribution of gap sizes in the
superconducting state. Despite the inhomogeneity, we find that every pairing
gap develops locally at a temperature Tp, following the relation 2D/kBTp = 8.
At very low doping (<0.14), systematic changes in the DOS indicate the presence
of another phenomenon, which is unrelated and perhaps competes with electron
pairing. Our observation of nanometre-sized pairing regions provides the
missing microscopic basis for understanding recent reports of fluctuating
superconducting response above Tc in hole-doped high-Tc copper oxide
superconductors.


title: Gravitational arcs as a perturbation of the perfect ring

abstract:
  The image of a point situated at the center of a circularly symmetric
potential is a perfect circle. The perturbative effect of non-symmetrical
potential terms is to displace and break the perfect circle. These 2 effects,
displacement and breaking are directly related to the Taylor expansion of the
perturbation at first order on the circle. The numerical accuracy of this
perturbative approach is tested in the case of an elliptical potential with a
core radius. The contour of the images and the caustics lines are well
re-produced by the perturbative approach. These results suggests that the
modeling of arcs, and in particular of tangential arcs may be simplified by
using a general perturbative representation on the circle. An interesting
feature of the perturbative approach, is that the equation of the caustic line
depends only on the values on the circle of the lens displacement field along
the $\theta$ direction.


title: Anatomy of bubbling solutions

abstract:
  We present a comprehensive analysis of holography for the bubbling solutions
of Lin-Lunin-Maldacena. These solutions are uniquely determined by a coloring
of a 2-plane, which was argued to correspond to the phase space of free
fermions. We show that in general this phase space distribution does not
determine fully the 1/2 BPS state of N=4 SYM that the gravitational solution is
dual to, but it does determine it enough so that vevs of all single trace 1/2
BPS operators in that state are uniquely determined to leading order in the
large N limit. These are precisely the vevs encoded in the asymptotics of the
LLM solutions. We extract these vevs for operators up to dimension 4 using
holographic renormalization and KK holography and show exact agreement with the
field theory expressions.


title: Can String Theory Predict the Weinberg Angle?

abstract:
  We investigate whether the hypercharge assignments in the Standard Model can
be interpreted as a hint at Grand Unification in the context of heterotic
string theory. To this end, we introduce a general method to calculate U(1)_Y
for any heterotic orbifold and compare our findings to the cases where
hypercharge arises from a GUT. Surprisingly, in the overwhelming majority of
3-2 Standard Models, a non-anomalous hypercharge direction can be defined, for
which the spectrum is vector-like. For these models, we calculate sin^2 theta
to see how well it agrees with the standard GUT value. We find that 12% have
sin^2 theta = 3/8, while all others have values which are less. Finally, 89% of
the models with sin^2 theta = 3/8 have U(1)_Y in SU(5).


title: Future of Chiral Extrapolations with Domain Wall Fermions

abstract:
  I discuss the constraints on the lattice spacing, a, the quark masses, m, the
box size, L, and particularly the residual mass, m_res, such that one can
successfully calculate phenomenologically interesting quantities using Domain
Wall fermions (DWF). The constraints on a, m, and L are largely common with
other improved fermion discretizations, and I emphasize that the improved
chiral symmetry of DWF does not remove the need for simulations with a
significant range of lattice parameters. Concerning m_res, I compare the
analysis of chiral symmetry breaking to that with Wilson fermions, emphasizing
that DWF are better than simply Wilson fermions with each chiral symmetry
breaking effect reduced by a common factor. I then discuss the impact of
non-zero m_res both on generic hadronic quantities, and on matrix elements
which involve mixing with lower dimension operators.


title: Random spatial growth with paralyzing obstacles

abstract:
  We study models of spatial growth processes where initially there are sources
of growth (indicated by the colour green) and sources of a growth-stopping
(paralyzing) substance (indicated by red). The green sources expand and may
merge with others (there is no `inter-green' competition). The red substance
remains passive as long as it is isolated. However, when a green cluster comes
in touch with the red substance, it is immediately invaded by the latter, stops
growing and starts to act as red substance itself. In our main model space is
represented by a graph, of which initially each vertex is randomly green, red
or white (vacant), and the growth of the green clusters is similar to that in
first-passage percolation. The main issues we investigate are whether the model
is well-defined on an infinite graph (e.g. the $d$-dimensional cubic lattice),
and what can be said about the distribution of the size of a green cluster just
before it is paralyzed. We show that, if the initial density of red vertices is
positive, and that of white vertices is sufficiently small, the model is indeed
well-defined and the above distribution has an exponential tail. In fact, we
believe this to be true whenever the initial density of red is positive. This
research also led to a relation between invasion percolation and critical
Bernoulli percolation which seems to be of independent interest.


title:
A Monte Carlo Study of the Irreducible Background in the EGRET
  Instrument

abstract:
  The diffuse extragalactic gamma-ray background (EGRB) has been derived by
various groups from observations by the Energetic Gamma Ray Experiment
Telescope (EGRET) instrument on the Compton Gamma Ray Observatory (CGRO). The
derived EGRB consists of gamma rays that may come from astrophysical
components, such as from unresolved extragalactic point sources (blazars,
normal galaxies, etc.), true extragalactic diffuse emission, misattributed
diffuse signals from the Galaxy and other celestial sources, and an irreducible
instrumental background due to gamma rays produced by cosmic-ray (CR)
interactions in the EGRET instrument. Using the Gamma Ray Large Area Space
Telescope (GLAST) simulation and reconstruction software, we have investigated
the magnitude of the irreducible instrumental background in the GLAST Large
Area Telescope. We re-scale our results to the EGRET and present preliminary
results of our study and its effect on current estimates of the EGRB.


title: The Diffuse Galactic Gamma-Ray Emission Model for GLAST LAT

abstract:
  Diffuse emission from the Milky Way dominates the gamma-ray sky. About 80% of
the high-energy luminosity of the Milky Way comes from processes in the
interstellar medium. The Galactic diffuse emission traces interactions of
energetic particles, primarily protons and electrons, with the interstellar gas
and radiation field, thus delivering information about cosmic-ray spectra and
interstellar mass in distant locations. Additionally, the Galactic diffuse
emission is the celestial foreground for the study of gamma-ray point sources
and the extragalactic diffuse gamma-ray emission. We report on the latest
developments in the modelling of the Galactic diffuse emission, which will be
used for the Gamma Ray Large Area Space Telescope (GLAST) investigations.


title: Non-solvable contractions of semisimple Lie algebras in low dimension

abstract:
  The problem of non-solvable contractions of Lie algebras is analyzed. By
means of a stability theorem, the problem is shown to be deeply related to the
embeddings among semisimple Lie algebras and the resulting branching rules for
representations. With this procedure, we determine all deformations of
indecomposable Lie algebras having a nontrivial Levi decomposition onto
semisimple Lie algebras of dimension $n\leq 8$, and obtain the non-solvable
contractions of the latter class of algebras.


title:
Two Erdos problems on lacunary sequences: Chromatic number and
  Diophantine approximation

abstract:
  Let ${n_k}$ be an increasing lacunary sequence, i.e., $n_{k+1}/n_k>1+r$ for
some $r>0$. In 1987, P. Erdos asked for the chromatic number of a graph $G$ on
the integers, where two integers $a,b$ are connected by an edge iff their
difference $|a-b|$ is in the sequence ${n_k}$. Y. Katznelson found a connection
to a Diophantine approximation problem (also due to Erdos): the existence of
$x$ in $(0,1)$ such that all the multiples $n_j x$ are at least distance
$\delta(x)>0$ from the set of integers. Katznelson bounded the chromatic number
of $G$ by $Cr^{-2}|\log r|$. We apply the Lov\'asz local lemma to establish
that $\delta(x)>cr|\log r|^{-1}$ for some $x$, which implies that the chromatic
number of $G$ is at most $Cr^{-1} |\log r|$. This is sharp up to the
logarithmic factor.


title: Long-term tidal evolution of short-period planets with companions

abstract:
  Of the fourteen transiting extrasolar planetary systems for which radii have
been measured, at least three appear to be considerably larger than theoretical
estimates suggest. It has been proposed by Bodenheimer, Lin & Mardling that
undetected companions acting to excite the orbital eccentricity are responsible
for these oversized planets, as they find new equilibrium radii in response to
being tidally heated. In the case of HD 209458, this hypothesis has been
rejected by some authors because there is no sign of such a companion at the 5
m/s level, and because it is difficult to say conclusively that the
eccentricity is non-zero. Transit timing analysis [...]. Whether or not a
companion is responsible for the large radius of HD 209458b, almost certainly
some short-period systems have companions which force their eccentricities to
nonzero values. This paper is dedicated to quantifying this effect.
  The eccentricity of a short-period planet will only be excited as long as its
(non-resonant) companion's eccentricity is non-zero. Here we show that the
latter decays on a timescale which depends on the structure of the interior
planet, a timescale which is often shorter than the lifetime of the system.
This includes Earth-mass planets in the habitable zones of some stars. We
determine which configurations are capable of sustaining significant
eccentricity for at least the age of the system, and show that these include
systems with companion masses as low as a fraction of an Earth mass. The
orbital parameters of such companions are consistent with recent calculations
which show that the migration process can induce the formation of low mass
planets external to the orbits of hot Jupiters. Systems with inflated planets
are therefore good targets in the search for terrestrial planets.


title:
On the End-to-End Distortion for a Buffered Transmission over Fading
  Channel

abstract:
  In this paper, we study the end-to-end distortion/delay tradeoff for a
analogue source transmitted over a fading channel. The analogue source is
quantized and stored in a buffer until it is transmitted. There are two extreme
cases as far as buffer delay is concerned: no delay and infinite delay. We
observe that there is a significant power gain by introducing a buffer delay.
Our goal is to investigate the situation between these two extremes. Using
recently proposed \emph{effective capacity} concept, we derive a closed-form
formula for this tradeoff. For SISO case, an asymptotically tight upper bound
for our distortion-delay curve is derived, which approaches to the infinite
delay lower bound as $\mathcal{D}_\infty \exp(\frac{C}{\tau_n})$, with $\tau_n$
is the normalized delay, $C$ is a constant. For more general MIMO channel, we
computed the distortion SNR exponent -- the exponential decay rate of the
expected distortion in the high SNR regime. Numerical results demonstrate that
introduction of a small amount delay can save significant transmission power.


title: Global Analysis of Nucleon Strange Form Factors at Low $Q^2$

abstract:
  We perform a global analysis of all recent experimental data from elastic
parity-violating electron scattering at low $Q^2$. The values of the electric
and magnetic strange form factors of the nucleon are determined at $Q^2 = 0.1$
GeV/$c^2$ to be $G^s_E = -0.008 \pm 0.016$ and $G^s_M = 0.29 \pm 0.21$.


title:
Zero-temperature phase of the XY spin glass in two dimensions: Genetic
  embedded matching heuristic

abstract:
  For many real spin-glass materials, the Edwards-Anderson model with
continuous-symmetry spins is more realistic than the rather better understood
Ising variant. In principle, the nature of an occurring spin-glass phase in
such systems might be inferred from an analysis of the zero-temperature
properties. Unfortunately, with few exceptions, the problem of finding
ground-state configurations is a non-polynomial problem computationally, such
that efficient approximation algorithms are called for. Here, we employ the
recently developed genetic embedded matching (GEM) heuristic to investigate the
nature of the zero-temperature phase of the bimodal XY spin glass in two
dimensions. We analyze bulk properties such as the asymptotic ground-state
energy and the phase diagram of disorder strength vs. disorder concentration.
For the case of a symmetric distribution of ferromagnetic and antiferromagnetic
bonds, we find that the ground state of the model is unique up to a global O(2)
rotation of the spins. In particular, there are no extensive degeneracies in
this model. The main focus of this work is on an investigation of the
excitation spectrum as probed by changing the boundary conditions. Using
appropriate finite-size scaling techniques, we consistently determine the
stiffness of spin and chiral domain walls and the corresponding fractal
dimensions. Most noteworthy, we find that the spin and chiral channels are
characterized by two distinct stiffness exponents and, consequently, the system
displays spin-chirality decoupling at large length scales. Results for the
overlap distribution do not support the possibility of a multitude of
thermodynamic pure states.


title: Quaternionic Wave Packets

abstract:
  We compare the behavior of a wave packet in the presence of a complex and a
pure quaternionic potential step. This analysis, done for a gaussian
convolution function, sheds new light on the possibility to recognize
quaternionic deviations from standard quantum mechanics.


title:
Conformational gel analysis and graphics: Measurement of side chain
  rotational isomer populations by NMR and molecular mechanics

abstract:
  Conformational gel analysis and graphics systematically identifies and
evaluates plausible alternatives to the side chain conformations found by
conventional peptide or protein structure determination methods. The proposed
analysis determines the populations of side chain rotational isomers and the
probability distribution of these populations. The following steps are repeated
for each side chain of a peptide or protein: first, extract the local molecular
mechanics of side chain rotational isomerization from a single representative
global conformation; second, expand the predominant set of rotational isomers
to include all probable rotational isomers down to those that constitute just a
small percentage of the population; and third, evaluate the constraints vicinal
coupling constants and NOESY cross relaxation rates place on rotational isomer
populations. In this article we apply conformational gel analysis to the cobalt
glycyl-leucine dipeptide and detail the steps necessary to generalize the
analysis to other amino acid side chains in other peptides and proteins. For a
side chain buried within a protein interior, it is noteworthy that the set of
probable rotational isomers may contain one or more rotational isomers that are
not identified by conventional NMR structure determination methods. In cases
such as this the conformational gel graphics fully accounts for the interplay
of molecular mechanics and NMR data constraints on the population estimates.
The analysis is particularly suited to identifying side chain rotational
isomers that constitute a small percentage of the population, but nevertheless
might be structurally and functionally very significant.


title: Dirac Equation Studies in the Tunnelling Energy Zone

abstract:
  We investigate the tunnelling zone V0 < E < V0+m for a one-dimensional
potential within the Dirac equation. We find the appearance of superluminal
transit times akin to the Hartman effect.


title: On the Vacuum Propagation of Gravitational Waves

abstract:
  We show that, for any local, causal quantum field theory which couples
covariantly to gravity, and which admits Minkowski spacetime vacuum(a)
invariant under the inhomogeneous proper orthochronous Lorentz group, plane
gravitational waves propagating in such Minkowski vacuum(a) do not dissipate
energy or momentum via quantum field theoretic effects.


title:
Single production of the doubly charged scalar in the littlest Higgs
  model

abstract:
  Single production of the doubly charged scalars $\Phi^{\pm\pm}$ via
$e\gamma$, $ep$ and $pp$ collisions is studied in the context of the little
Higgs$(LH)$ model. Our numerical results show that the new particles
$\Phi^{\pm\pm}$ can be abundantly produced and their possible signatures should
be detected in future high energy linear $e^{+}e^{-}$ collider$(ILC)$. The
cross section for single production of $\Phi^{\pm\pm}$ at the $LHC$ is much
smaller than that at the $ILC$ or the $THERA$.