title:
A Bayesian approach to the follow-up of candidate gravitational wave
  signals

abstract:
  Ground-based gravitational wave laser interferometers (LIGO, GEO-600, Virgo
and Tama-300) have now reached high sensitivity and duty cycle. We present a
Bayesian evidence-based approach to the search for gravitational waves, in
particular aimed at the followup of candidate events generated by the analysis
pipeline. We introduce and demonstrate an efficient method to compute the
evidence and odds ratio between different models, and illustrate this approach
using the specific case of the gravitational wave signal generated during the
inspiral phase of binary systems, modelled at the leading quadrupole Newtonian
order, in synthetic noise. We show that the method is effective in detecting
signals at the detection threshold and it is robust against (some types of)
instrumental artefacts. The computational efficiency of this method makes it
scalable to the analysis of all the triggers generated by the analysis
pipelines to search for coalescing binaries in surveys with ground-based
interferometers, and to a whole variety of signal waveforms, characterised by a
larger number of parameters.


title:
Artificial Immune Systems (AIS) - A New Paradigm for Heuristic Decision
  Making

abstract:
  Over the last few years, more and more heuristic decision making techniques
have been inspired by nature, e.g. evolutionary algorithms, ant colony
optimisation and simulated annealing. More recently, a novel computational
intelligence technique inspired by immunology has emerged, called Artificial
Immune Systems (AIS). This immune system inspired technique has already been
useful in solving some computational problems. In this keynote, we will very
briefly describe the immune system metaphors that are relevant to AIS. We will
then give some illustrative real-world problems suitable for AIS use and show a
step-by-step algorithm walkthrough. A comparison of AIS to other well-known
algorithms and areas for future work will round this keynote off. It should be
noted that as AIS is still a young and evolving field, there is not yet a fixed
algorithm template and hence actual implementations might differ somewhat from
the examples given here.


title: Inverse-Compton emission from the lobes of 3C 353

abstract:
  X-ray emission due to inverse-Compton scattering of microwave background
photons by electrons in the lobes of powerful radio galaxies has now been seen
in a large number of objects. Combining an inverse-Compton model for the lobe
X-ray emission with information obtained from radio synchrotron emission
provides a method of constraining the electron population and magnetic field
energy density, which cannot be accomplished using the radio data alone. Using
six frequencies of new and archival radio data and new XMM-Newton observations
of the Fanaroff & Riley class II radio galaxy 3C353, we show that
inverse-Compton emission is detected in the radio lobes of this source at a
level consistent with what is seen in other objects. We argue that variations
in the X-ray/radio ratio in the brighter eastern lobe require positionally
varying magnetic field strength. We also examine the X-ray nucleus and the
cluster, Zw 1819.1-0108, spatially and spectrally.


title:
Interferometric Mapping of Magnetic Fields: The massive star forming
  region G34.4+0.23 MM

abstract:
  We report millimeter interferometric observations of polarized continuum and
line emission from the massive star forming region G34.4. Polarized thermal
dust emission at 3 mm wavelength and CO $J=1 \to 0$ line emission were observed
using the Berkeley-Illinois-Maryland Association (BIMA) array. Our results show
a remarkably uniform polarization pattern in both dust and in CO J=$1 \to 0$
emission. In addition, the line emission presents a consistent uniform
polarization pattern over most of the velocity channel maps. These uniform
polarization patterns are aligned with the north-south main axis of the
filament between the main millimeter source (MM) and the ultra-compact H
{\scriptsize II} region, which are the central sources in G34.4, suggesting a
magnetic field orthogonal to this axis. This morphology is consistent with a
magnetically supported disk seen roughly edge-on.


title: New 6-cm observations of a large sample of radio SNRs

abstract:
  Almost 50 radio SNR objects were selected from Green's catalogue for
continuum and polarization observations. We present preliminary results of this
observational campaign at 4.7 GHz carried out with Torun 32-metre radio
telescope.


title:
Heat Capacity and Magnetic Phase Diagram of the Low-Dimensional
  Antiferromagnet Y$_2$BaCuO$_5$

abstract:
  A study by specific heat of a polycrystalline sample of the low-dimensional
magnetic system Y$_2$BaCuO$_5$ is presented. Magnetic fields up to 14 T are
applied and permit to extract the ($T$,$H$) phase diagram. Below
$\mu_0H^*\simeq2$ T, the N\'eel temperature, associated with a
three-dimensional antiferromagnetic long-range ordering, is constant and equals
$T_N=15.6$ K. Above $H^*$, $T_N$ increases linearly with $H$ and a
field-induced increase of the entropy at $T_N$ is related to the presence of an
isosbestic point at $T_X\simeq20$ K, where all the specific heat curves cross.
A comparison is made between Y$_2$BaCuO$_5$ and the quasi-two-dimensional
magnetic systems BaNi$_{2}$V$_{2}$O$_{8}$, Sr$_2$CuO$_2$Cl$_2$, and
Pr$_2$CuO$_4$, for which very similar phase diagrams have been reported. An
effective field-induced magnetic anisotropy is proposed to explain these phase
diagrams.


title:
Global Properties of X-Ray Flashes and X-Ray-Rich Gamma-Ray Bursts
  Observed by Swift

abstract:
  We describe and discuss the spectral and temporal characteristics of the
prompt emission and X-ray afterglow emission of X-ray flashes (XRFs) and
X-ray-rich gamma-ray bursts (XRRs) detected and observed by Swift between
December 2004 and September 2006. We compare these characteristics to a sample
of conventional classical gamma-ray bursts (C-GRBs) observed during the same
period. We confirm the correlation between Epeak_obs and fluence noted by
others and find further evidence that XRFs, XRRs and C-GRBs form a continuum.
We also confirm that our known redshift sample is consistent with the
correlation between the peak energy in the GRB rest frame (Epeak_src) and the
isotropic radiated energy (Eiso), so called the Epeak_src-Eiso relation. The
spectral properties of X-ray afterglows of XRFs and C-GRBs are similar, but the
temporal properties of XRFs and C-GRBs are quite different. We found that the
light curves of C-GRB afterglows show a break to steeper indices
(shallow-to-steep break) at much earlier times than do XRF afterglows.
Moreover, the overall luminosity of XRF X-ray afterglows is systematically
smaller by a factor of two or more compared to that of C-GRBs. These distinct
differences between the X-ray afterglows of XRFs and C-GRBs may be the key to
understanding not only the mysterious shallow-to-steep break in X-ray afterglow
light curves, but also the unique nature of XRFs.


title: Two finiteness theorem for $(a,b)$-module

abstract:
  We prove the following two results
  1. For a proper holomorphic function $ f : X \to D$ of a complex manifold
  $X$ on a disc such that $\{df = 0 \} \subset f^{-1}(0)$, we construct, in a
functorial way, for each integer $p$, a geometric (a,b)-module $E^p$ \
associated to the (filtered) Gauss-Manin connexion of $f$.
  This first theorem is an existence/finiteness result which shows that
geometric (a,b)-modules may be used in global situations.
  2. For any regular (a,b)-module $E$ we give an integer $N(E)$, explicitely
given from simple invariants of $E$, such that the isomorphism class of
$E\big/b^{N(E)}.E$ determines the isomorphism class of $E$.
  This second result allows to cut asymptotic expansions (in powers of $b$) \
of elements of $E$ without loosing any information.


title: Benchmark scenarios for the NMSSM

abstract:
  We discuss constrained and semi--constrained versions of the
next--to--minimal supersymmetric extension of the Standard Model (NMSSM) in
which a singlet Higgs superfield is added to the two doublet superfields that
are present in the minimal extension (MSSM). This leads to a richer Higgs and
neutralino spectrum and allows for many interesting phenomena that are not
present in the MSSM. In particular, light Higgs particles are still allowed by
current constraints and could appear as decay products of the heavier Higgs
states, rendering their search rather difficult at the LHC. We propose
benchmark scenarios which address the new phenomenological features, consistent
with present constraints from colliders and with the dark matter relic density,
and with (semi--)universal soft terms at the GUT scale. We present the
corresponding spectra for the Higgs particles, their couplings to gauge bosons
and fermions and their most important decay branching ratios. A brief survey of
the search strategies for these states at the LHC is given.


title:
Pure-state transformations and catalysis under operations that
  completely preserve positivity of partial transpose

abstract:
  Motivated by the desire to better understand the class of quantum operations
on bipartite systems that preserve positivity of partial transpose (PPT
operations) and its relation to the class LOCC (local operations and classical
communication), we present some results on deterministic bipartite pure state
transformations by PPT operations. Restricting our attention to the case where
we start with a rank K maximally entangled state, we give a necessary condition
for transforming it into a given pure state, which we show is also sufficient
when K is two and the final state has Schmidt rank three. We show that it is
sufficient for all K and all final states provided a conjecture about a certain
family of semidefinite programs is true. We also demonstrate that the
phenomenon of catalysis can occur under PPT operations and that, unlike LOCC
catalysis, a maximally entangled state can be a catalyst. Finally, we give a
necessary and sufficient condition for the possibility of transforming a rank K
maximally entangled state to an arbitrary pure state by PPT operations assisted
by some maximally entangled catalyst.


title: Full Counting Statistics as the Geometry of Two Planes

abstract:
  Provided the measuring time is short enough, the full counting statistics
(FCS) of the charge pumped across a barrier as a result of a series of voltage
pulses are shown to be equivalent to the geometry of two planes. This
formulation leads to the FCS without the need for the usual non-equilibrium
(Keldysh) transport theory or the direct computation of the determinant of an
infinite-dimensional matrix. In the particular case of the application of N
Lorentzian pulses, we show the computation of the FCS reduces to the
diagonalization of an N x N matrix. We also use the formulation to compute the
core-hole response in the X-ray edge problem and the FCS for a square wave
pulse-train for the case of low transmission.


title: Quasiparticle excitations in relativistic quantum field theory

abstract:
  We analyze the particle-like excitations arising in relativistic field
theories in states different than the vacuum. The basic properties
characterizing the quasiparticle propagation are studied using two different
complementary methods. First we introduce a frequency-based approach, wherein
the quasiparticle properties are deduced from the spectral analysis of the
two-point propagators. Second, we put forward a real-time approach, wherein the
quantum state corresponding to the quasiparticle excitation is explicitly
constructed, and the time-evolution is followed. Both methods lead to the same
result: the energy and decay rate of the quasiparticles are determined by the
real and imaginary parts of the retarded self-energy respectively. Both
approaches are compared, on the one hand, with the standard field-theoretic
analysis of particles in the vacuum and, on the other hand, with the
mean-field-based techniques in general backgrounds.


title:
Mildly relativistic X-ray transient 080109 and SN2008D: Towards a
  continuum from energetic GRB/XRF to ordinary Ibc SN

abstract:
  We analyze the hitherto available space-based X-ray data as well as
ground-based optical data of the X-ray transient 080109/SN2008D. From the data
we suggest that (i) The initial transient (\lesssim 800 sec) is attributed to
the reverse shock emission of a mildly relativistic (\Gamma \sim a few) outflow
stalled by the dense stellar wind. (ii) The subsequent X-ray afterglow
(\lesssim 2\times 10^4 sec) can be ascribed to the forward shock emission of
the outflow, with a kinetic energy \sim 10^{46} erg, when sweeping up the
stellar wind medium. (iii) The late X-ray flattening (\gtrsim 2\times 10^4$
sec) is powered by the fastest non-decelerated component of SN2008D's ejecta.
(iv) The local event rate of X-ray transient has a lower limit of \sim
1.6\times 10^4 yr^{-1} Gpc^{-3}, indicating a vast majority of X-ray transients
have a wide opening angle of \gtrsim 100 degree. The off-axis viewing model is
less likely. (v) Transient 080109/SN2008D may lead to a continuum from GRB-SN
to under-luminous GRB-/XRF-SN to X-ray transient-SN and to ordinary Ibc SN (if
not every Ibc SN has a relativistic jet), as shown in Figure 2 of this Letter.


title:
A general stochastic maximum principle for optimal control problems of
  forward-backward systems

abstract:
  Stochastic maximum principle of nonlinear controlled forward-backward
systems, where the set of strict (classical) controls need not be convex and
the diffusion coefficient depends explicitly on the variable control, is an
open problem impossible to solve by the classical method of spike variation. In
this paper, we introduce a new approach to solve this open problem and we
establish necessary as well as sufficient conditions of optimality, in the form
of global stochastic maximum principle, for two models. The first concerns the
relaxed controls, who are a measure-valued processes. The second is a
restriction of the first to strict control problems.


title: Luttinger liquid fixed point for a 2D flat Fermi surface

abstract:
  We consider a system of 2D interacting fermions with a flat Fermi surface.
The apparent conflict between Luttinger and non Luttinger liquid behavior found
through different approximations is resolved by showing the existence of a line
of non trivial fixed points, for the RG flow, corresponding to Luttinger liquid
behavior; the presence of marginally relevant operators can cause flow away
from the fixed point. The analysis is non-perturbative and based on the
implementation, at each RG iteration, of Ward Identities obtained from local
phase transformations depending on the Fermi surface side, implying the partial
vanishing of the Beta function.


title: The most rapidly rotating He-strong emission line star: HR7355

abstract:
  Using archival spectroscopic and photometric data, we searched for massive
stars with Balmer-emission consistent with magnetically confined circumstellar
material. HR 7355 is a formerly unknown He-strong star showing Balmer emission.
At V=6.02 mag, it is one of the brightest objects simultaneously showing
anomalous helium absorption and hydrogen emission. Among similar objects, only
sigma Ori E has so far been subjected to any systematic analysis of the
circumstellar material responsible for the emission. We argue that the
double-wave photometric period of 0.52d corresponds to the rotation period. In
tandem with the high projected equatorial velocity, v sin i=320 km/s, this
short period suggests that HR 7355 is the most rapidly rotating He-strong star
known to date; a class that was hitherto expected to host stars with slow to
moderate rotation only.


title: Estimators of Long-Memory: Fourier versus Wavelets

abstract:
  There have been a number of papers written on semi-parametric estimation
methods of the long-memory exponent of a time series, some applied, others
theoretical. Some using Fourier methods, others using a wavelet-based
technique. In this paper, we compare the Fourier and wavelet approaches to the
local regression method and to the local Whittle method. We provide an overview
of these methods, describe what has been done, indicate the available results
and the conditions under which they hold. We discuss their relative strengths
and weaknesses both from a practical and a theoretical perspective. We also
include a simulation-based comparison. The software written to support this
work is available on demand and we illustrate its use at the end of the paper.


title: Proton-proton fusion in pionless effective theory

abstract:
  The proton-proton fusion reaction, $pp\to de^+\nu$, is studied in pionless
effective field theory (EFT) with di-baryon fields up to next-to leading order.
With the aid of the di-baryon fields, the effective range corrections are
naturally resummed up to the infinite order and thus the calculation is greatly
simplified. Furthermore, the low-energy constant which appears in the
axial-current-di-baryon-di-baryon contact vertex is fixed through the ratio of
two- and one-body matrix elements which reproduces the tritium lifetime very
precisely. As a result we can perform a parameter free calculation for the
process. We compare our numerical result with those from the accurate potential
model and previous pionless EFT calculations, and find a good agreement within
the accuracy better than 1%.


title:
Structured environments in solid state systems: crossover from Gaussian
  to non-Gaussian behavior

abstract:
  The variety of noise sources typical of the solid state represents the main
limitation toward the realization of controllable and reliable quantum
nanocircuits, as those allowing quantum computation. Such ``structured
environments'' are characterized by a non-monotonous noise spectrum sometimes
showing resonances at selected frequencies. Here we focus on a prototype
structured environment model: a two-state impurity linearly coupled to a
dissipative harmonic bath. We identify the time scale separating Gaussian and
non-Gaussian dynamical regimes of the Spin-Boson impurity. By using a
path-integral approach we show that a qubit interacting with such a structured
bath may probe the variety of environmental dynamical regimes.


title:
Necessary Optimality Condition for a Discrete Dead Oil Isotherm Optimal
  Control Problem

abstract:
  We obtain necessary optimality conditions for a semi-discretized optimal
control problem for the classical system of nonlinear partial differential
equations modelling the water-oil (isothermal dead-oil model).


title:
New type of ellipsometry in infrared spectroscopy: The double-reference
  method

abstract:
  We have developed a conceptually new type of ellipsometry which allows the
determination of the complex refractive index by simultaneously measuring the
unpolarized normal-incidence reflectivity relative to the vacuum and to another
reference media. From these two quantities the complex optical response can be
directly obtained without Kramers-Kronig transformation. Due to its
transparency and large refractive index over a broad range of the spectrum,
from the far-infrared to the soft ultraviolet region, diamond can be ideally
used as a second reference. The experimental arrangement is rather simple
compared to other ellipsometric techniques.


title:
Universal photocurrent-voltage characteristics of dye sensitized
  nanocrystalline TiO$_2$ photoelectrochemical cells

abstract:
  We propose a new linearizable model for the nonlinear photocurrent-voltage
characteristics of nanocrystalline TiO$_2$ dye sensitized solar cells based on
first principles and report predicted values for fill factors. Upon
renormalization diverse experimental photocurrent-voltage data collapse onto a
single universal function. These advances allow the estimation of the complete
current-voltage curve and the fill factor from any three experimental data
points, e.g., the open circuit voltage, the short circuit current and one
intermediate measurement. The theoretical underpinning provides insight into
the physical mechanisms responsible for the remarkably large fill factors as
well as their known dependence on the open circuit voltage.


title: Recovering the topology of the IGM at z~2

abstract:
  We investigate how well the 3D density field of neutral hydrogen in the
Intergalactic Medium (IGM) can be reconstructed using the Lyman-alpha
absorptions observed along lines of sight to quasars separated by arcmin
distances in projection on the sky. We use cosmological hydrodynamical
simulations to compare the topologies of different fields: dark matter, gas and
neutral hydrogen optical depth and to investigate how well the topology of the
IGM can be recovered from the Wiener interpolation method implemented by Pichon
et al. (2001). The global statistical and topological properties of the
recovered field are analyzed quantitatively through the power-spectrum, the
probability distribution function (PDF), the Euler characteristics, its
associated critical point counts and the filling factor of underdense regions.
The local geometrical properties of the field are analysed using the local
skeleton by defining the concept of inter-skeleton distance. At scales larger
than ~1.4 <d_LOS>, where <d_LOS> is the mean separation between lines of sight,
the reconstruction accurately recovers the topological features of the large
scale density distribution of the gas, in particular the filamentary
structures. At scales larger than the intrinsic smoothing length of the
inversion procedure, the power spectrum of the recovered HI density field
matches well that of the original one and the low order moments of the PDF are
well recovered as well as the shape of the Euler characteristic. The integral
errors on the PDF and the critical point counts are indeed small, less than 20%
for <d_LOS>~2.5 arcmin. The small deviations between the reconstruction and the
exact solution mainly reflect departures from the log-normal behaviour that are
ascribed to highly non-linear objects in overdense regions.


title: Parametric Integer Programming in Fixed Dimension

abstract:
  We consider the following problem: Given a rational matrix $A \in \setQ^{m
\times n}$ and a rational polyhedron $Q \subseteq\setR^{m+p}$, decide if for
all vectors $b \in \setR^m$, for which there exists an integral $z \in \setZ^p$
such that $(b, z) \in Q$, the system of linear inequalities $A x \leq b$ has an
integral solution. We show that there exists an algorithm that solves this
problem in polynomial time if $p$ and $n$ are fixed. This extends a result of
Kannan (1990) who established such an algorithm for the case when, in addition
to $p$ and $n$, the affine dimension of $Q$ is fixed.
  As an application of this result, we describe an algorithm to find the
maximum difference between the optimum values of an integer program $\max \{c x
: A x \leq b, x \in \setZ^n \}$ and its linear programming relaxation over all
right-hand sides $b$, for which the integer program is feasible. The algorithm
is polynomial if $n$ is fixed. This is an extension of a recent result of
Ho\c{s}ten and Sturmfels (2003) who presented such an algorithm for integer
programs in standard form.


title: Emergence of firms in $(d+1)$-dimensional work space

abstract:
  Standard micro-economics concentrate on the description of markets but is
seldom interested in production. Several economists discussed the concept of a
firm, as opposed to an open labour market where entrepreneurs would recrute
workers on the occasion of each business opportunity. Coase \cite{Coase} is one
of them, who explains the existence of firms as institution because they reduce
the transaction costs with respect to an open labour market. Whatever the
rationale proposed by economists to account for the existence of firms, their
perspective is based on efficiency and cost analysis. Little attention is paid
to the dynamics of emergence and evolution of firms. The aim of the present
manuscript is to check the global dynamical properties of a very simple model
based on bounded rationality and reinforcement learning.
  Workers and managers are localised on a lattice and they choose collaborators
on the basis of the success of previous work relations. The choice algorithm is
largely inspired rom the observation and modeling of long term customer/sellers
relationships observed on perishable goods markets discussed in Weisbuch
etal\cite{Weisbuch} and Nadal etal\cite{Nadal}. The model presented here is in
no way an alternative to Coase. We describe the build-up of long term
relationships which do reduce transaction costs, and we deduce the dynamical
properties of networks built from our simple assumptions.
  In conclusion, the present model explains the metastability of employment
relations in the firm, but something has to be added to it to explain the more
efficient workload repartition observed in real firms.


title:
Seyfert galaxies in the local Universe (z$\leq$ 0.1): the average X-ray
  spectrum as seen by $BeppoSAX$

abstract:
  The $BeppoSAX$ archive is currently the largest reservoir of high sensitivity
simultaneous soft and hard-X ray data of Seyfert galaxies. From this database
all the Seyfert galaxies (105 objects of which 43 are type I and 62 are type
II) with redshift lower than 0.1 have been selected and analyzed in a
homogeneous way (Dadina 2007). The X-ray data so collected allow to infer the
average spectral properties of nearby Seyfert galaxies included in the original
sample and, most notably: the photon index ($\Gamma$$\sim$1.8), the high-energy
cut-off (Ec$\sim$290 keV), and the relative amount of reflection (R$\sim$1.0).
The data have been also used to test some assumptions of the unified scheme for
the AGN. The distributions of the isotropic indicators (photon index, relative
amount of reflection, high-energy cut-off and narrow FeK$\alpha$ energy
centroid) are similar in type I and type II objects while the absorbing column
and the iron line equivalent width significantly differ between the two classes
of active galactic nuclei. Confirming previous results, the narrow FeK$\alpha$
line is consistent, in Seyfert 2, with being produced in the same matter
responsible for the observed obscuration. These results, thus, support the
basic picture of the unified model. Moreover, the presence of a X-ray Baldwin
effect in Seyfert 1 has been here measured using the 20-100 keV luminosity
(EW$\propto$L(20-100)$^{-0.22\pm0.05}$). Finally, the possible presence of a
correlation between the photon index and the amount of reflection is confirmed
thus indicating thermal Comptonization as the most likely origin of the high
energy emission for the active galactic nuclei included in the original sample.


title: Mimicking general relativity in the solar system

abstract:
  In order for a modified gravity model to be a candidate for cosmological dark
energy it has to pass stringent local gravity experiments. We find that a
Brans-Dicke (BD) theory with well-defined second order corrections that include
the Gauss-Bonnet term possess this feature. We construct the generic second
order theory that gives, to linear order, a BD metric solution for a point-like
mass source. We find that these theories interpolate between general relativity
(GR) and BD gravity. In particular it is found that the relevant Eddington
parameter, that is commonly heavily constrained by time delay experiments, can
be arbitrarily close to the GR value of 1, with an arbitrary BD parameter. We
find the region where the solution is stable to small timelike perturbations.


title: The Seyfert galaxies in the local Universe: from BeppoSAX to Simbol-X

abstract:
  The operational conditions found by $BeppoSAX$ in observing nearby
(z$\leq$0.1) Seyferts were reproduced for $Simbol$-$X$ in order to simulate a
realistic final database of the mission. The results indicate that, even in the
worst conditions, the $Simbol$-$X$ archive of pointings will allow to fully
characterize the high-energy spectrum of nearby Seyferts and, most importantly,
to obtain solid results on R and Ec (fundamental to model the cosmic X-Ray
background, CXB). The measurement of the inclination angle of the accretion
disk will be possible for $\sim$15 objects allowing to directly test the
unified models for AGN. Finally, the time-dependent characteristics of the
reflected component will be studied in at least $\sim$25 objects.


title: The log-periodic-AR(1)-GARCH(1,1) model for financial crashes

abstract:
  This paper intends to meet recent claims for the attainment of more rigorous
statistical methodology within the econophysics literature. To this end, we
consider an econometric approach to investigate the outcomes of the
log-periodic model of price movements, which has been largely used to forecast
financial crashes. In order to accomplish reliable statistical inference for
unknown parameters, we incorporate an autoregressive dynamic and a conditional
heteroskedasticity structure in the error term of the original model, yielding
the log-periodic-AR(1)-GARCH(1,1) model. Both the original and the extended
models are fitted to financial indices of U. S. market, namely S&P500 and
NASDAQ. Our analysis reveal two main points: (i) the
log-periodic-AR(1)-GARCH(1,1) model has residuals with better statistical
properties and (ii) the estimation of the parameter concerning the time of the
financial crash has been improved.


title: Radiating black hole solutions in arbitrary dimensions

abstract:
  We prove a theorem that characterizes a large family of non-static solutions
to Einstein equations in $N$-dimensional space-time, representing, in general,
spherically symmetric Type II fluid. It is shown that the best known
Vaidya-based (radiating) black hole solutions to Einstein equations, in both
four dimensions (4D) and higher dimensions (HD), are particular cases from this
family. The spherically symmetric static black hole solutions for Type I fluid
can also be retrieved. A brief discussion on the energy conditions,
singularities and horizons is provided.


title: Chiral restoration in excited nucleons versus SU(6)

abstract:
  We compare axial charges of excited nucleons, as predicted by the chiral
symmetry restoration picture, with the traditional, moderately successful for
the ground-state baryons SU(6) symmetry. The axial charges of excited nucleons
can (and will) be measured in lattice QCD simulations, and comparison of the
lattice results with the two different symmetry schemes will give an insight on
the origins of the excited hadron masses as well as on interrelations of chiral
symmetry and confinement.


title:
Sr lattice clock at 1x10^{-16} fractional uncertainty by remote optical
  evaluation with a Ca clock

abstract:
  Optical atomic clocks promise timekeeping at the highest precision and
accuracy, owing to their high operating frequencies. Rigorous evaluations of
these clocks require direct comparisons between them. We have realized a
high-performance remote comparison of optical clocks over km-scale urban
distances, a key step for development, dissemination, and application of these
optical standards. Through this remote comparison and a proper design of
lattice-confined neutral atoms for clock operation, we evaluate the uncertainty
of a strontium (Sr) optical lattice clock at the 1x10-16 fractional level,
surpassing the best current evaluations of cesium (Cs) primary standards. We
also report on the observation of density-dependent effects in the
spin-polarized fermionic sample and discuss the current limiting effect of
blackbody radiation-induced frequency shifts.


title: Limit leaves of a CMC lamination are stable

abstract:
  Suppose ${\cal L}$ is a lamination of a Riemannian manifold by hypersurfaces
with the same constant mean curvature. We prove that every limit leaf of ${\cal
L}$ is stable for the Jacobi operator. A simple but important consequence of
this result is that the set of stable leaves of ${\cal L}$ has the structure of
a lamination.


title: Anti-B --> X(s) gamma in two universal extra dimensions

abstract:
  We calculate the leading order corrections to the anti-B --> X(s) gamma decay
in the standard model with two large flat universal extra dimensions. We find
that the contributions involving the exchange of Kaluza-Klein modes of the
physical scalar field a^+-_(kl) depend logarithmically on the ultraviolet
cut-off scale Lambda. We emphasize that all flavor-changing neutral current
transitions suffer from this problem. Although the ultraviolet sensitivity
weakens the lower bound on the inverse compactification radius 1/R that follows
from anti-B --> X(s) gamma, the constraint remains stronger than any other
available direct measurement. After performing a careful study of the potential
impact of cut-off and higher-order effects, we find 1/R > 650 GeV at 95%
confidence level if errors are combined in quadrature. Our limit is at variance
with the parameter region 1/R <~ 600 GeV preferred by dark matter constraints.


title: A quark model analysis of the Sivers function

abstract:
  We develop a formalism to evaluate the Sivers function. The approach is well
suited for calculations which use constituent quark models to describe the
structure of the nucleon. A non-relativistic reduction of the scheme is
performed and applied to the Isgur-Karl model of hadron structure. The results
obtained are consistent with a sizable Sivers effect and the signs for the u
and d flavor contributions turn out to be opposite. This pattern is in
agreement with the one found analyzing, in the same model, the impact parameter
dependent generalized parton distributions. The Burkardt Sum Rule turns out to
be fulfilled to a large extent. We estimate the QCD evolution of our results
from the momentum scale of the model to the experimental one and obtain
reasonable agreement with the available data.


title: Imprint of first stars era in the cosmic infrared backround fluctuations

abstract:
  We present the latest results on CIB fluctuations from early epochs from deep
Spitzer data. The results show the existence of significant CIB fluctuations at
the IRAC wavelengths (3.6 to 8 mic) which remain after removing galaxies down
to very faint levels. These fluctuations must arise from populations with a
significant clustering component, but only low levels of the shot noise. There
are no correlations between the source-subtracted IRAC maps and the
corresponding fields observed with the HST ACS at optical wavelengths. Taken
together, these data imply that 1) the sources producing the CIB fluctuations
are individually faint with S_\nu< a few nJy at 3.6 and 4.5 mic; 2) have
different clustering pattern than the more recent galaxy populations; 3) are
located within the first 0.7 Gyr (unless these fluctuations can somehow be
produced by - so far unobserved - local galaxies of extremely low luminosity
and with the unusual for local populations clustering pattern), 4) produce
contribution to the net CIB flux of at least 1-2 nW/m^2/sr at 3.6 and 4.5 mic
and must have mass-to-light ratio significantly below the present-day
populations, and 5) they have angular density of ~ a few per arcsec^2 and are
in the confusion of the present day instruments, but can be individually
observable with JWST.


title: Metastable gauged O'Raifeartaigh

abstract:
  We study the possibility of obtaining metastable supersymmetry breaking vacua
in a perturbative gauge theory without singlet fields, thus allowing for
scenarios where a grand unified symmetry and supersymmetry are broken by the
same sector. We show some explicit SU(5) examples. The minimal renormalizable
example requires the use of two adjoints, but it is shown to inevitably lead to
unwanted light states. We suggest various alternatives, and show that the
viable possibilities consist of allowing for non-renormalizable operators, of
employing four adjoints or of adding at least one field in a different
representation.


title:
Qualitative Analysis of Forced Response of Blisks With Friction Ring
  Dampers

abstract:
  A damping strategy for blisks (integrally bladed disks) of turbomachinery
involving a friction ring is investigated. These rings, located in grooves
underside the wheel of the blisks, are held in contact by centrifugal loads and
the energy is dissipated when relative motions between the ring and the disk
occur. A representative lumped parameter model of the system is introduced and
the steady-state nonlinear response is derived using a multi-harmonic balance
method combined with an AFT procedure where the friction force is calculated in
the time domain. Numerical simulations are presented for several damper
characteristics and several excitation configurations. From these results, the
performance of this damping strategy is discussed and some design guidelines
are given.


title:
Dynamics of a linear oscillator connected to a small strongly non-linear
  hysteretic absorber

abstract:
  The present investigation deals with the dynamics of a two-degrees-of-freedom
system which consists of a main linear oscillator and a strongly nonlinear
absorber with small mass. The nonlinear oscillator has a softening hysteretic
characteristic represented by a Bouc-Wen model. The periodic solutions of this
system are studied and their calcu- lation is performed through an averaging
procedure. The study of nonlinear modes and their stability shows, under
specific conditions, the existence of localization which is responsible for a
passive irreversible energy transfer from the linear oscillator to the
nonlinear one. The dissipative effect of the nonlinearity appears to play an
important role in the energy transfer phenomenon and some design criteria can
be drawn regarding this parameter among others to optimize this energy
transfer. The free transient response is investigated and it is shown that the
energy transfer appears when the energy input is sufficient in accordance with
the predictions from the nonlinear modes. Finally, the steady-state forced
response of the system is investigated. When the input of energy is sufficient,
the resonant response (close to nonlinear modes) experiences localization of
the vibrations in the nonlinear absorber and jump phenomena.


title: Quantum Monte Carlo simulation of two-dimensional Emery model

abstract:
  The Quantum Monte Carlo simulation of the two-dimensional Emery model of the
CuO2 plane of hight Tc superconductors were performed. The method based on the
direct-space proposed by Suzuki and Hirsch was used. Contrary to the method
based on the Hubbard-Stratonovich transformation, the states generated by this
method are basis states in occupation number representation, i. e.
configurations of fermions can be observed on real two-dimensional array.Energy
and specific heat were computed for different dopings. Specific heat curves
show peaks at low temperature which could be assigned to electronic
transitions. Quantity similar to current-current correlation function were
computed. The static electric conductivity curves obtained by this way show
metal-insulator transitions and two different metallic behaviours. On the
direct-space states generated at low temperature and zero doping, the fermions
form antiferromagnetic loops while they form antiferromagnetic chains for other
dopings. The loops seem to appear when the conductivity becomes zero while yhe
conductivity increases with the numbers of chains but superconductivity is not
unambiguously evident.


title:
Plane-wave based electronic structure calculations for correlated
  materials using dynamical mean-field theory and projected local orbitals

abstract:
  The description of realistic strongly correlated systems has recently
advanced through the combination of density functional theory in the local
density approximation (LDA) and dynamical mean field theory (DMFT). This
LDA+DMFT method is able to treat both strongly correlated insulators and
metals. Several interfaces between LDA and DMFT have been used, such as (N-th
order) Linear Muffin Tin Orbitals or Maximally localized Wannier Functions.
Such schemes are however either complex in use or additional simplifications
are often performed (i.e., the atomic sphere approximation). We present an
alternative implementation of LDA+DMFT, which keeps the precision of the
Wannier implementation, but which is lighter. It relies on the projection of
localized orbitals onto a restricted set of Kohn-Sham states to define the
correlated subspace. The method is implemented within the Projector Augmented
Wave (PAW) and within the Mixed Basis Pseudopotential (MBPP) frameworks. This
opens the way to electronic structure calculations within LDA+DMFT for more
complex structures with the precision of an all-electron method. We present an
application to two correlated systems, namely SrVO3 and beta-NiS (a
charge-transfer material), including ligand states in the basis-set. The
results are compared to calculations done with Maximally Localized Wannier
functions, and the physical features appearing in the orbitally resolved
spectral functions are discussed.


title: Microscopic Formulation of Puff Field Theory

abstract:
  We describe a generalization of Puff Field Theory to p+1 dimensions where 0
\le p \le 5. We then focus on the case of p=0, ``Puff Quantum Mechanics,'' and
construct a formulation independent of string theory.


title: TER: A Robot for Remote Ultrasonic Examination: Experimental Evaluations

abstract:
  This chapter:
  o Motivates the clinical use of robotic tele-echography
  o Introduces the TER system
  o Describes technical and clinical evaluations performed with TER


title:
Effect of Crystal-Field Splitting and Inter-Band Hybridization on the
  Metal-Insulator Transitions of Strongly Correlated Systems

abstract:
  We investigate a quarter-filled two-band Hubbard model involving a
crystal-field splitting, which lifts the orbital degeneracy as well as an
inter-orbital hopping (inter-band hybridization). Both terms are relevant to
the realistic description of correlated materials such as transition-metal
oxides. The nature of the Mott metal-insulator transition is clarified and is
found to depend on the magnitude of the crystal-field splitting. At large
values of the splitting, a transition from a two-band to a one-band metal is
first found as the on-site repulsion is increased and is followed by a Mott
transition for the remaining band, which follows the single-band
(Brinkman-Rice) scenario well documented previously within dynamical mean-field
theory. At small values of the crystal-field splitting, a direct transition
from a two-band metal to a Mott insulator with partial orbital polarization is
found, which takes place simultaneously for both orbitals. This transition is
characterized by a vanishing of the quasiparticle weight for the majority
orbital but has a first-order character for the minority orbital. It is pointed
out that finite-temperature effects may easily turn the metallic regime into a
bad metal close to the orbital polarization transition in the metallic phase.


title:
Heavy Quarkonium Production in Single Transverse Polarized High Energy
  Scattering

abstract:
  We formulate the single transverse spin asymmetry in heavy quarkonium
production in lepton-nucleon and nucleon-nucleon collisions in the
non-relativistic limit. We find that the asymmetry is very sensitive to the
production mechanism. The final state interactions with the heavy quark and
antiquark cancel out among themselves when the pair are produced in a
color-single configuration, or cancel out with the initial state interaction in
pp scattering when they are in color-octet. As a consequence, the asymmetry is
nonzero in ep collisions only in the color-octet model, whereas in pp
collisions only in the color-singlet model.


title:
Linear almost Poisson structures and Hamilton-Jacobi equation.
  Applications to nonholonomic Mechanics

abstract:
  In this paper, we study the underlying geometry in the classical
Hamilton-Jacobi equation. The proposed formalism is also valid for nonholonomic
systems. We first introduce the essential geometric ingredients: a vector
bundle, a linear almost Poisson structure and a Hamiltonian function, both on
the dual bundle (a Hamiltonian system). From them, it is possible to formulate
the Hamilton-Jacobi equation, obtaining as a particular case, the classical
theory. The main application in this paper is to nonholonomic mechanical
systems. For it, we first construct the linear almost Poisson structure on the
dual space of the vector bundle of admissible directions, and then, apply the
Hamilton-Jacobi theorem. Another important fact in our paper is the use of the
orbit theorem to symplify the Hamilton-Jacobi equation, the introduction of the
notion of morphisms preserving the Hamiltonian system; indeed, this concept
will be very useful to treat with reduction procedures for systems with
symmetries. Several detailed examples are given to illustrate the utility of
these new developments.


title: Hyperfine structure of S states in Li and Be^+

abstract:
  A large-scale configuration-interaction (CI) calculation is reported for the
hyperfine splitting of the 2^2S and 3^2S states of ^7Li and ^9Be^+. The CI
calculation based on the Dirac-Coulomb-Breit Hamiltonian is supplemented with a
separate treatment of the QED, nuclear-size, nuclear-magnetization
distribution, and recoil corrections. The nonrelativistic limit of the CI
results is in excellent agreement with variational calculations. The
theoretical values obtained for the hyperfine splitting are complete to the
relative order of \alpha^2 and improve upon results of previous studies.


title: Some properties of the k-dimensional Lyness' map

abstract:
  This paper is devoted to study some properties of the k-dimensional Lyness'
map. Our main result presentes a rational vector field that gives a Lie
symmetry for F. This vector field is used, for k less or equal to 5 to give
information about the nature of the invariant sets under F. When k is odd, we
also present a new (as far as we know) first integral for F^2 which allows to
deduce in a very simple way several properties of the dynamical system
generated by F. In particular for this case we prove that, except on a given
codimension one algebraic set, none of the positive initial conditions can be a
periodic point of odd period.


title:
Initial condition for hydrodynamics, partonic free streaming, and the
  uniform description of soft observables at RHIC

abstract:
  We investigate the role of the initial condition used for the hydrodynamic
evolution of the system formed in ultra-relativistic heavy-ion collisions and
find that an appropriate choice motivated by the models of early-stage
dynamics, specifically a simple two-dimensional Gaussian profile, leads to a
uniform description of soft observables measured in the Relativistic Heavy-Ion
Collider (RHIC). In particular, the transverse-momentum spectra, the
elliptic-flow, and the Hanbury-Brown--Twiss correlation radii, including the
ratio R_out/R_side as well as the dependence of the radii on the azimuthal
angle (azHBT), are properly described. We use the perfect-fluid hydrodynamics
with a realistic equation of state based on lattice calculations and the
hadronic gas at high and low temperatures, respectively. We also show that the
inclusion of the partonic free-streaming in the early stage allows to delay the
start of the hydrodynamical description to comfortable times of the order of 1
fm/c. Free streaming broadens the initial energy-density profile, but generates
the initial transverse and elliptic flow. The data may be described equally
well when the hydrodynamics is started early, or with a delay due to partonic
free-streaming.


title:
Evolution of progenitor stars of Type Ibc supernovae and long gamma-ray
  bursts

abstract:
  We discuss how rotation and binary interactions may be related to the
diversity of type Ibc supernovae and long gamma-ray bursts. After presenting
recent evolutionary models of massive single and binary stars including
rotation, the Tayler-Spruit dynamo and binary interactions, we argue that the
nature of SNe Ibc progenitors from binary systems may not significantly differ
from that of single star progenitors in terms of rotation, and that most long
GRB progenitors may be produced via the quasi-chemically homogeneous evolution
at sub-solar metallicity. We also briefly discuss the possible role of magnetic
fields generated in the convective core of a massive star for the transport of
angular momentum, which is potentially important for future stellar evolution
models of supernova and GRB progenitors.


title: SUSY GUTs with Yukawa unification: a go/no-go study using FCNC processes

abstract:
  We address the viability of exact Yukawa unification in the context of
general SUSY GUTs with universal soft-breaking sfermion and gaugino mass terms
at the GUT scale. We find that this possibility is challenged, unless the
squark spectrum is pushed well above the limits allowed by naturalness. This
conclusion is assessed through a global fit using electroweak observables and
quark flavour-changing neutral current (FCNC) processes. The problem is mostly
the impossibility of accommodating simultaneously the bottom mass and the BR(B
--> Xs gamma), after the stringent CDF upper bound on the decay Bs --> mu^+
mu^- is taken into account, and under the basic assumption that the b --> s
gamma amplitude have like sign with respect to the Standard Model one, as
indicated by the B --> Xs l^+ l^- data.
  With the same strategy, we also consider the possibility of relaxing Yukawa
unification to b - tau Yukawa unification. We find that with small departures
from the condition tan beta ~= 50, holding when Yukawa unification is exact,
the mentioned tension is substantially relieved. We emphasize that in the
region where fits are successful the lightest part of the SUSY spectrum is
basically fixed by the requirements of b - tau unification and the applied FCNC
constraints. As such, it is easily falsifiable once the LHC turns on.


title: Scott's problem for proper Scott sets

abstract:
  I show that assuming PFA, every proper Scott set is the standard system of a
model of PA. A Scott set X is proper if it is arithmetically closed and the
quotient Boolean algebra X/Fin is a proper partial order.


title: Complex dynamics of a Holling-type IV predator-prey model

abstract:
  In this paper, we focus on a spatial Holling-type IV predator-prey model
which contains some important factors, such as diffusion, noise (random
fluctuations) and external periodic forcing. By a brief stability and
bifurcation analysis, we arrive at the Hopf and Turing bifurcation surface and
derive the symbolic conditions for Hopf and Turing bifurcation in the spatial
domain. Based on the stability and bifurcation analysis, we obtain spiral
pattern formation via numerical simulation. Additionally, we study the model
with colored noise and external periodic forcing. From the numerical results,
we know that noise or external periodic forcing can induce instability and
enhance the oscillation of the species, and resonant response. Our results show
that modeling by reaction-diffusion equations is an appropriate tool for
investigating fundamental mechanisms of complex spatiotemporal dynamics.


title:
The stability of conditional Markov processes and Markov chains in
  random environments

abstract:
  We consider a discrete time hidden Markov model where the signal is a
stationary Markov chain. When conditioned on the observations, the signal is a
Markov chain in a random environment under the conditional measure. It is shown
that this conditional signal is weakly ergodic when the signal is ergodic and
the observations are nondegenerate. This permits a delicate exchange of the
intersection and supremum of $\sigma$-fields, which is key for the stability of
the nonlinear filter and partially resolves a long-standing gap in the proof of
a result of Kunita [J. Multivariate Anal. 1 (1971) 365--393]. A similar result
is obtained also in the continuous time setting. The proofs are based on an
ergodic theorem for Markov chains in random environments in a general state
space.


title: Knotted surfaces in 4-manifolds

abstract:
  Fintushel and Stern have proved that if S \subset X is a symplectic surface
in a symplectic 4-manifold such that S has simply-connected complement and
nonnegative self-intersection, then there are infinitely many topologically
equivalent but smoothly distinct embedded surfaces homologous to S. Here we
extend this result to include symplectic surfaces whose self-intersection is
bounded below by 2-2g, where g is the genus of S.
  We make use of tools from Heegaard Floer theory, and include several results
that may be of independent interest. Specifically we give an analogue for
Ozsvath-Szabo invariants of the Fintushel-Stern knot surgery formula for
Seiberg-Witten invariants, both for closed 4-manifolds and manifolds with
boundary. This is based on a formula for the Ozsvath-Szabo invariants of the
result of a logarithmic transformation, analogous to one obtained by
Morgan-Mrowka-Szab\'o for Seiberg-Witten invariants, and the results on
Ozsvath-Szabo invariants of fiber sums due to the author and Jabuka. In
addition, we give a calculation of the twisted Heegaard Floer homology of
circle bundles of "large" degree over Riemann surfaces.


title: Proper and piecewise proper families of reals

abstract:
  I introduced the notions of proper and piecewise proper families of reals to
make progress on an open question in the field of models of PA about whether
every Scott set is the standard system of a model of PA. A family of reals X is
proper if it is arithmetically closed and the quotient Boolean algebra X/fin is
a proper poset. A family is piecewise proper if it is the union of a chain of
proper families of size $\leq\omega_1$. Here, I explore the question of the
existence of proper and piecewise proper families of reals of different
cardinalities.


title: A new method for studying the vibration of non-homogeneous membranes

abstract:
  We present a method to solve the Helmholtz equation for a non-homogeneous
membrane with Dirichlet boundary conditions at the border of arbitrary
two-dimensional domains. The method uses a collocation approach based on a set
of localized functions, called "little sinc functions", which are used to
discretize two-dimensional regions. We have performed extensive numerical tests
and we have compared the results obtained with the present method with the ones
available from the literature. Our results show that the present method is very
accurate and that its implementation for general problems is straightforward.


title: Observation of negative absolute resistance in a Josephson junction

abstract:
  We experimentally demonstrate the occurrence of negative absolute resistance
(NAR) up to about $-1\Omega$ in response to an externally applied dc current
for a shunted Nb-Al/AlO$_x$-Nb Josephson junction, exposed to a microwave
current at frequencies in the GHz range. The realization (or not) of NAR
depends crucially on the amplitude of the applied microwave current.
Theoretically, the system is described by means of the resistively and
capacitively shunted junction model in terms of a moderately damped, classical
Brownian particle dynamics in a one-dimensional potential. We find excellent
agreement of the experimental results with numerical simulations of the model.


title:
Flux-Limited Diffusion Approximation Models of Giant Planet Formation by
  Disk Instability

abstract:
  Both core accretion and disk instability appear to be required as formation
mechanisms in order to explain the entire range of giant planets found in
extrasolar planetary systems. Disk instability is based on the formation of
clumps in a marginally-gravitationally unstable protoplanetary disk. These
clumps can only be expected to contract and survive to become protoplanets if
they are able to lose thermal energy through a combination of convection and
radiative cooling. Here we present several new three dimensional, radiative
hydrodynamics models of self-gravitating protoplanetary disks, where radiative
transfer is handled in the flux-limited diffusion approximation. We show that
while the flux-limited models lead to higher midplane temperatures than in a
diffusion approximation model without the flux-limiter, the difference in
temperatures does not appear to be sufficiently high to have any significant
effect on the formation of self-gravitating clumps. Self-gravitating clumps
form rapidly in the models both with and without the flux-limiter. These models
suggest that the reason for the different outcomes of numerical models of disk
instability by different groups cannot be attributed solely to the handling of
radiative transfer, but rather appears to be caused by a range of numerical
effects and assumptions. Given the observational imperative to have disk
instability form at least some extrasolar planets, these models imply that disk
instability remains as a viable giant planet formation mechanism.


title:
Magnetic Field Evolution in Neutron Stars: One-Dimensional Multi-Fluid
  Model

abstract:
  This paper is the first in a series aimed at understanding the long-term
evolution of neutron star magnetic fields. We model the stellar matter as an
electrically neutral and lightly ionized plasma composed of three moving
particle species: neutrons, protons, and electrons, which can be converted into
each other by weak interactions (beta decays), suffer binary collisions, and be
affected by each other's macroscopic electromagnetic fields. Since the
evolution of the magnetic field occurs over thousands of years or more,
compared to dynamical time scales (sound and Alfv\'en) of milliseconds to
seconds, we use a slow-motion approximation in which we neglect the inertial
terms in the equations of motion for the particles. We restrict ourselves to a
one-dimensional geometry in which the magnetic field points in one Cartesian
direction but varies only along an orthogonal direction. We study the evolution
of the system in three different ways: (i) estimating time scales directly from
the equations, guided by physical intuition; (ii) a normal-mode analysis in the
limit of a nearly uniform system; and (iii) a finite-difference numerical
integration of the equations of motion. We find good agreement between our
analytical normal-mode solutions and the numerical simulations. We show that
the magnetic field and the particles evolve through successive
quasi-equilibrium states, on time scales that can be understood by physical
arguments. Depending of the parameter values the magnetic field can evolve by
ohmic diffusion or by ambipolar diffusion, the latter being limited either by
interparticle collisions or by relaxation to chemical equilibrium through beta
decays. The numerical simulations are further validated by verifying that they
satisfy the known conservation laws also in highly non-linear situations.


title:
Evolution of massive stars at very low metallicity including rotation
  and binary interactions

abstract:
  We discuss recent models on the evolution of massive stars at very low
metallicity including the effects of rotation, magnetic fields and binarity.
Very metal poor stars lose very little mass and angular momentum during the
main sequence evolution, and rotation plays a dominant role in their evolution.
In rapidly rotating massive stars, the rotationally induced mixing time scale
can be even shorter than the nuclear time scale throughout the main sequence.
The consequent quasi-chemically homogeneous evolution greatly differs from the
standard massive star evolution that leads to formation of red giants with
strong chemical stratification. Interesting outcomes of such a new mode of
evolution include the formation of rapidly rotating massive Wolf-Rayet stars
that emit large amounts of ionizing photons, the formation of a long gamma-ray
bursts and a hypernovae, and the production of large amounts of primary
nitrogen. We show that binary interactions can further enhance the effects of
rotation, as mass accretion in a close binary spins up the secondary.


title: Novel patterns for vector mesons from the large-Nc limit

abstract:
  We report on a relation between the decay constants of \rho-like
J^{PC}=1^{--} vector mesons, which arises solely from the perturbative analysis
of the VV, TT and VT correlators at order \alpha_s^0 in the large-N_c limit. We
find f_{V}^T/f_{V}=1/\sqrt{2} for highly excited states together with a pattern
of alternation in sign. Quite remarkably, recent lattice determinations
reported f_{\rho}^T/f_{\rho}=0.72(2), in excellent agreement with our large-N_c
result. This seems to suggest a pattern like f_{Vn}^T/f_{Vn}=(-1)^n/\sqrt{2}
for the whole (1^{--}) states. In order to test this conjecture in real QCD we
construct a set of spectral sum rules, which turn out to comply nicely with
this scenario.


title:
Measurement of Ratios of Fragmentation Fractions for Bottom Hadrons in
  p-pbar Collisions at sqrt{s}=1.96 TeV

abstract:
  This paper describes the first measurement of b-quark fragmentation fractions
into bottom hadrons in Run II of the Tevatron Collider at Fermilab. The result
is based on a 360 pb-1 sample of data collected with the CDF II detector in
p-pbar collisions at sqrt{s}=1.96 TeV. Semileptonic decays of B0, B+, and B_s
mesons, as well as Lambda_b baryons, are reconstructed. For an effective bottom
hadron p_T threshold of 7 GeV/c, the fragmentation fractions are measured to be
f_u/f_d=1.054 +/- 0.018 (stat) +0.025-0.045(sys) +/- 0.058 (Br),
f_s/(f_u+f_d)=0.160 +/- 0.005 (stat) +0.011-0.010 (sys) +0.057-0.034 (Br), and
f_{Lambda_b}/(f_u+f_d)=0.281\pm0.012 (stat) +0.058-0.056 (sys) +0.128-0.086
(Br), where the uncertainty (Br) is due to uncertainties on measured branching
ratios. The value of f_s/(f_u+f_d) agrees within one standard deviation with
previous CDF measurements and the world average of this quantity, which is
dominated by LEP measurements. However, the ratio f_{Lambda_b}/(f_u+f_d) is
approximately twice the value previously measured at LEP. The approximately 2
sigma discrepancy is examined in terms of kinematic differences between the two
production environments.


title: Lecture notes on high energy cosmic rays

abstract:
  I give a concise introduction into high energy cosmic ray physics, including
also few related aspects of high energy gamma-ray and neutrino astrophysics.
The main emphasis is placed on astrophysical questions, and the level of the
presentation is kept basic.


title:
Resolving the inner active accretion disk around the Herbig Be star MWC
  147 with VLTI/MIDI+AMBER spectro-interferometry

abstract:
  We studied the geometry of the inner (AU-scale) circumstellar environment
around the Herbig Be star MWC 147. Combining, for the first time, near- (NIR, K
band) and mid-infrared (MIR, N band) spectro-interferometry on a Herbig star,
our VLTI/MIDI and AMBER data constrain not only the geometry of the brightness
distribution, but also the radial temperature distribution in the disk.
  For our detailed modeling of the interferometric data and the spectral energy
distribution, we employ 2-D radiation transfer simulations, showing that
passive irradiated Keplerian dust disks can easily fit the SED, but predict
much lower visibilities than observed. Models of a Keplerian disk with emission
from an optically thick inner gaseous accretion disk (inside the dust
sublimation zone), however, yield a good fit of the SED and simultaneously
reproduce the observed NIR and MIR visibilities. We conclude that the NIR
continuum emission from MWC 147 is dominated by accretion luminosity emerging
from an optically thick inner gaseous disk, while the MIR emission also
contains strong contributions from the outer dust disk.


title: Constraining Supersymmetric Dark Matter With Synchrotron Measurements

abstract:
  The annihilations of neutralino dark matter (or other dark matter candidate)
generate, among other Standard Model states, electrons and positrons. These
particles emit synchrotron photons as a result of their interaction with the
Galactic Magnetic Field. In this letter, we use the measurements of the WMAP
satellite to constrain the intensity of this synchrotron emission and, in turn,
the annihilation cross section of the lightest neutralino. We find this
constraint to be more stringent than that provided by any other current
indirect detection channel. In particular, the neutralino annihilation cross
section must be less than ~ 3 x 10^-26 cm^3/s (1 x 10^25 cm^3/s) for 100 GeV
(500 GeV) neutralinos distributed with an NFW halo profile. For the
conservative case of an entirely flat dark matter distribution within the inner
8 kiloparsecs of the Milky Way, the constraint is approximately a factor of 30
less stringent. Even in this conservative case, synchrotron measurements
strongly constrain, for example, the possibility of wino or higgsino neutralino
dark matter produced non-thermally in the early universe.


title: Dependence of the BALQSO fraction on Radio Luminosity

abstract:
  We find that the fraction of classical Broad Absorption Line quasars
(BALQSOs) among the FIRST radio sources in the Sloan Data Release 3, is
20.5^{+7.3}_{-5.9}% at the faintest radio powers detected (L_{\rm 1.4
GHz}~10^{32} erg/s), and rapidly drops to <8% at L_{\rm 1.4 GHz}~3*10^{33}
erg/s. Similarly, adopting the broader Absorption Index (AI) definition of
Trump et al. (2006) we find the fraction of radio BALQSOs to be
44^{+8.1}_{-7.8}% reducing to 23.1^{+7.3}_{-6.1}% at high luminosities. While
the high fraction at low radio power is consistent with the recent near-IR
estimates by Dai et al. (2008), the lower fraction at high radio powers is
intriguing and confirms previous claims based on smaller samples. The trend is
independent of the redshift range, the optical and radio flux selection limits,
or the exact definition of a radio match. We also find that at fixed optical
magnitude, the highest bins of radio luminosity are preferentially populated by
non-BALQSOs, consistent with the overall trend. We do find, however, that those
quasars identified as AI-BALQSOs but \emph{not} under the classical definition,
do not show a significant drop in their fraction as a function of radio power,
further supporting independent claims for which these sources, characterized by
lower equivalent width, may represent an independent class with respect to the
classical BALQSOs. We find the balnicity index, a measure of the absorption
trough in BALQSOs, and the mean maximum wind velocity to be roughly constant at
all radio powers. We discuss several plausible physical models which may
explain the observed fast drop in the fraction of the classical BALQSOs with
increasing radio power, \emph{although no one is entirely satisfactory}.
(abridged).


title:
Combined analysis of the integrated Sachs-Wolfe effect and cosmological
  implications

abstract:
  We present a global measurement of the integrated Sachs-Wolfe (ISW) effect
obtained by cross-correlating all relevant large scale galaxy data sets with
the cosmic microwave background radiation map provided by the Wilkinson
Microwave Anisotropy Probe. With these measurements, the overall ISW signal is
detected at the ~ 4.5 sigma level. We also examine the cosmological
implications of these measurements, particularly the dark energy equation of
state w, its sound speed, and the overall curvature of the Universe. The flat
LCDM model is a good fit to the data and, assuming this model, we find that the
ISW data constrain Omega_m = 0.20 +0.19 -0.11 at the 95% confidence level. When
we combine our ISW results with the latest baryon oscillation and supernovae
measurements, we find that the result is still consistent with a flat LCDM
model with w = -1 out to redshifts z > 1.


title: The galaxy luminosity function and its evolution with Chandra

abstract:
  AIMS: We have compiled one of the largest normal-galaxy samples ever to probe
X-ray luminosity function evolution separately for early and late-type systems.
  METHODS: We selected 207 normal galaxies up to redshift z~1.4, with data from
four major Chandra X-ray surveys, namely the Chandra deep fields (north, south
and extended) and XBootes, and a combination of X-ray and optical criteria. We
used template spectral energy-distribution fitting to obtain separate early-
and late-type sub-samples, made up of 101 and 106 systems, respectively. For
the full sample, as well as the two sub-samples, we obtained luminosity
functions using both a non-parametric and a parametric, maximum-likelihood
method.
  RESULTS: For the full sample, the non-parametric method strongly suggests
luminosity evolution with redshift. The maximum-likelihood estimate shows that
this evolution follows ~(1+z)^k_total, k_total=2.2+-0.3. For the late-type
sub-sample, we obtained k_late=2.4^+1.0_-2.0. We detected no significant
evolution in the early-type sub-sample. The distributions of early and
late-type systems with redshift show that late types dominate at z>~0.5 and
hence drive the observed evolution for the total sample.
  CONCLUSIONS: Our results support previous results in X-ray and other
wavebands, which suggests luminosity evolution with k=2-3.


title: Low-Level Nuclear Activity in Nearby Spiral Galaxies

abstract:
  We are conducting a search for supermassive black holes (SMBHs) with masses
below 10^7 M_sun by looking for signs of extremely low-level nuclear activity
in nearby galaxies that are not known to be AGNs. Our survey has the following
characteristics: (a) X-ray selection using the Chandra X-ray Observatory, since
x-rays are a ubiquitous feature of AGNs; (b) Emphasis on late-type spiral and
dwarf galaxies, as the galaxies most likely to have low-mass SMBHs; (c) Use of
multiwavelength data to verify the source is an AGN; and (d) Use of the highest
angular resolution available for observations in x-rays and other bands, to
separate nuclear from off-nuclear sources and to minimize contamination by host
galaxy light. Here we show the feasibility of this technique to find AGNs by
applying it to six nearby, face-on spiral galaxies (NGC 3169, NGC 3184, NGC
4102, NGC 4647, NGC 4713, NGC 5457) for which data already exist in the Chandra
archive. All six show nuclear x-ray sources. The data as they exist at present
are ambiguous regarding the nature of the nuclear x-ray sources in NGC 4713 and
NGC 4647. We conclude, in accord with previous studies, that NGC 3169 and NGC
4102 are almost certainly AGNs. Most interestingly, a strong argument can be
made that NGC 3184 and NGC 5457, both of type Scd, host AGNs.


title: Dynamical Soft-Wall AdS/QCD

abstract:
  We present a solution of the five-dimensional gravity-dilaton-tachyon
equations of motion with a pure AdS_5 metric and a quadratic dilaton and linear
tachyon in conformal coordinates. This leads to an infrared soft wall model
where the dilaton profile gives rise to linear Regge trajectories for the
four-dimensional mass spectrum of the dual gauge theory. Even though our
approach is phenomenological the scalar fields resemble the dilaton and the
closed string tachyon of a non-critical string theory. Interestingly, the
linear tachyon has the correct profile to imply that chiral symmetry is not
restored for highly excited states. Our solution thus provides a dynamical
bottom-up model of linear confinement in holographic QCD.


title: Within-host HIV models with periodic antiretroviral therapy

abstract:
  This paper investigates the effect of drug treatment on the standard
within-host HIV model, assuming that therapy occurs periodically. It is shown
that eradication is possible under these periodic regimes, and we
quantitatively characterize successful drugs or drug combinations, both
theoretically and numerically. We also consider certain optimization problems,
motivated for instance, by the fact that eradication should be achieved at
acceptable toxicity levels to the patient. It turns out that these optimization
problems can be simplified considerably, and this makes calculations of the
optima a fairly straightforward task. All our results will be illustrated by
means of numerical examples based on up-to-date knowledge of parameter values
in the model.


title: Numerical studies of Casimir interactions

abstract:
  We study numerically the Casimir interaction between dielectrics in both two
and three dimensions. We demonstrate how sparse matrix factorizations enable
one to study torsional interactions in three dimensions. In two dimensions we
study the full cross-over between non-retarded and retarded interactions as a
function of separation. We use constrained factorizations in order to measure
the interaction of a particle with a rough dielectric surface and compare with
a scaling argument.


title: The X-ray luminosity function of galaxies and its evolution

abstract:
  We compile one of the largest ever samples to probe the X-ray normal galaxy
luminosity function and its evolution with cosmic time. In particular, we
select 207 galaxies (106 late and 101 early-type systems) from the Chandra Deep
Field North and South surveys, the Extended Chandra Deep Field South and the
XBOOTES survey. We derive the luminosity function separately for the total
(early+late), the early and the late-type samples using both a parametric
maximum likelihood method, and a variant of the non-parametric 1/V_m method.
Although the statistics is limited, we find that the total (early+late) galaxy
sample is consistent with a Pure Luminosity evolution model where the
luminosity evolves according to L(z) ~ (1+z)^2.2. The late-type systems appear
to drive this trend while the early-type systems show much weaker evidence for
evolution. We argue that the X-ray evolution of late-type systems is consistent
with that of blue galaxies in the optical. In contrast there is a mismatch
between the X-ray evolution of early-type systems and that of red galaxies at
optical wavelengths.


title: Magnetized Neutron Star Mergers and Gravitational Wave Signals

abstract:
  We investigate the influence of magnetic fields upon the dynamics of and
resulting gravitational waves from a binary neutron star merger in full general
relativity coupled to ideal magnetohydrodynamics (MHD). We consider two merger
scenarios, one where the stars begin with initially aligned poloidal magnetic
fields and one with no magnetic field. Both mergers result in a strongly
differentially rotating object. In comparison to the non-magnetized scenario,
the aligned magnetic fields delay the final merger of the two stars. During and
after merger we observe phenomena driven by the magnetic field, including
Kelvin-Helmholtz instabilities in shear layers, winding of the field lines, and
transition from poloidal to toroidal fields. These effects not only produce
electromagnetic radiation, but also can have a strong influence on the
gravitational waves. Thus, there are promising prospects for studying such
systems with both types of waves.


title: The Low Mass X-ray Binary - Globular Cluster Link and its Implications

abstract:
  Studies of nearby elliptical and S0 galaxies reveal that roughly half of the
low mass X-ray binaries (LMXBs), which are luminous tracers of accreting
neutron star or black hole systems, are in clusters. There is a surprising
tendency of LMXBs to be preferentially associated with metal-rich globular
clusters (GCs), with metal-rich GCs hosting three times as many LMXBs as
metal-poor ones. There is no convincing evidence of a correlation with GC age
so far. In some galaxies the LMXB formation rate varies with GC color even
within the metal-rich peak of the typical bimodal cluster metallicity
distribution. This provides some of the strongest evidence to date that there
are metallicity variations within the metal-rich GC peak, as is expected in
hierarchical galaxy formation scenarios. We also note that apparent
correlations between the interaction rates in GCs and LMXB frequency may not be
reliable because of the uncertainties in some GC parameters. We argue in fact
that there are considerable uncertainties in the integrated properties of even
the Milky Way clusters that are often overlooked.


title: Measuring Z' couplings at the LHC

abstract:
  We study the properties of potential new Z' gauge bosons produced through the
Drell-Yan mechanism at the LHC. Our analysis is performed using a fully
differential next-to-leading order QCD calculation with spin correlations,
interference effects, and experimental acceptances included. We examine the
distinguishability of different models and the feasibility of extracting
general coupling information with statistical, residual scale, and current
parton distribution function error estimates included. We extend a previous
parametrization of Z' couplings to include parity-violating coupling
combinations, and introduce a convenient technique for simulating new gauge
bosons on-peak using the concept of basis models. We illustrate our procedure
using several example Z' models. We find that one can extract reliably four
combinations of generation-independent quark and lepton couplings in our
analysis. For a Z' mass of 1.5 TeV, one can determine coupling information very
well assuming 100 fb^{-1} of integrated luminosity, and a precise measurement
becomes possible with 1 ab^{-1} at the SLHC. For a 3 TeV mass, a reasonable
determination requires the SLHC.


title:
Particle Acceleration, Magnetic Field Generation, and Associated
  Emission in Collisionless Relativistic Jets

abstract:
  Nonthermal radiation observed from astrophysical systems containing
relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray
bursts (GRBs), and Galactic microquasar systems usually have power-law emission
spectra. Recent PIC simulations using injected relativistic electron-ion
(electro-positron) jets show that acceleration occurs within the downstream
jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas.
Plasma waves and their associated instabilities (e.g., the Buneman instability,
other two-streaming instability, and the Weibel instability) created in the
shocks are responsible for particle (electron, positron, and ion) acceleration.
The simulation results show that the Weibel instability is responsible for
generating and amplifying highly nonuniform, small-scale magnetic fields. These
magnetic fields contribute to the electron's transverse deflection behind the
jet head. The ``jitter'' radiation from deflected electrons has different
properties than synchrotron radiation which assumes a uniform magnetic field.
This jitter radiation may be important to understanding the complex time
evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and
supernova remnants.


title: Orbital order driven quantum criticality

abstract:
  Charge, spin, and orbital degrees of freedom underlie the physics of
transition metal compounds. Much work has revealed quantum critical points
associated with spin and charge degrees of freedom in many of these systems.
Here we illustrate that the simplest models that embody the orbital degrees of
freedom - the two- and three-dimensional quantum orbital compass models -
exhibit an exact quantum critical behavior on diluted square and cubic lattices
(with a doping fraction of 1/4 and 1/2 respectively). This raises the
possibility of quantum critical points triggered by the degradation of orbital
order upon doping (or applying pressure to) such transition metal systems. We
prove the existence of an orbital spin glass in several related systems in
which the orbital couplings are made non-uniform. Moreover, a new orbital
Larmor precession (i.e., a periodic change in the orbital state) is predicted
when uniaxial pressure is applied.


title: Incidence Modules for Symplectic Spaces in Characteristic Two

abstract:
  We study the permutation action of a finite symplectic group of
characteristic 2 on the set of subspaces of its standard module which are
either totally isotropic or else complementary to totally isotropic subspaces
with respect to the alternating form. A general formula is obtained for the
2-rank of the incidence matrix for the inclusion of one-dimensional subspaces
in the distinguished subspaces of a fixed dimension.


title: Symmetric and Quasi-Symmetric Functions associated to Polymatroids

abstract:
  To every subspace arrangement X we will associate symmetric functions P[X]
and H[X]. These symmetric functions encode the Hilbert series and the minimal
projective resolution of the product ideal associated to the subspace
arrangement. They can be defined for discrete polymatroids as well. The
invariant H[X] specializes to the Tutte polynomial T[X]. Billera, Jia and
Reiner recently introduced a quasi-symmetric function F[X] (for matroids) which
behaves valuatively with respect to matroid base polytope decompositions. We
will define a quasi-symmetric function G[X] for polymatroids which has this
property as well. Moreover, G[X] specializes to P[X], H[X], T[X] and F[X].


title:
Domain wall delocalization, dynamics and fluctuations in an exclusion
  process with two internal states

abstract:
  We investigate the delocalization transition appearing in an exclusion
process with two internal states resp. on two parallel lanes. At the
transition, delocalized domain walls form in the density profiles of both
internal states, in agreement with a mean-field approach. Remarkably, the
topology of the system's phase diagram allows for the delocalization of a
(localized) domain wall when approaching the transition. We quantify the domain
wall's delocalization close to the transition by analytic results obtained
within the framework of the domain wall picture. Power-law dependences of the
domain wall width on the distance to the delocalization transition as well as
on the system size are uncovered, they agree with numerical results.


title:
Transition from 12 to near-24 hours glucose circadian rhythm on
  relaxation of a hyperglycemic condition

abstract:
  A composite, exponential relaxation function, modulated by a periodic
component, was used to fit to an experimental time series of blood glucose
levels. The 11 parameters function that allows for the detection of a possible
rhythm transition was fitted to the experimental time series using a genetic
algorithm. It has been found that the relaxation from a hyperglycemic condition
following a change in the anti-diabetic treatment, can be characterized by a
change from an initial 12 hours ultradian rhythm to a near-24 hours circadian
rhythm.


title:
On bicycle tire tracks geometry, hatchet planimeter, Menzin's conjecture
  and oscillation of unicycle tracks

abstract:
  The model of a bicycle is a unit segment AB that can move in the plane so
that it remains tangent to the trajectory of point A (the rear wheel is fixed
on the bicycle frame); the same model describes the hatchet planimeter. The
trajectory of the front wheel and the initial position of the bicycle uniquely
determine its motion and its terminal position; the monodromy map sending the
initial position to the terminal one arises. According to R. Foote's theorem,
this mapping of a circle to a circle is a Moebius transformation. We extend
this result to multi-dimensional setting. Moebius transformations belong to one
of the three types: elliptic, parabolic and hyperbolic. We prove a 100 years
old Menzin's conjecture: if the front wheel track is an oval with area at least
pi then the respective monodromy is hyperbolic. We also study bicycle motions
introduced by D. Finn in which the rear wheel follows the track of the front
wheel. Such a ''unicycle" track becomes more and more oscillatory in forward
direction. We prove that it cannot be infinitely extended backward and relate
the problem to the geometry of the space of forward semi-infinite equilateral
linkages.


title:
One-Dimensional Impenetrable Anyons in Thermal Equilibrium. I. Anyonic
  Generalization of Lenard's Formula

abstract:
  We have obtained an expansion of the reduced density matrices (or,
equivalently, correlation functions of the fields) of impenetrable
one-dimensional anyons in terms of the reduced density matrices of fermions
using the mapping between anyon and fermion wavefunctions. This is the
generalization to anyonic statistics of the result obtained by A. Lenard for
bosons. In the case of impenetrable but otherwise free anyons with statistical
parameter $\kappa$, the anyonic reduced density matrices in the grand canonical
ensemble is expressed as Fredholm minors of the integral operator ($1-\gamma
\hat \theta_T$) with complex statistics-dependent coefficient $\gamma=(1+e^{\pm
i\pi\kappa})/ \pi$. For $\kappa=0$ we recover the bosonic case of Lenard
$\gamma=2/\pi$. Due to nonconservation of parity, the anyonic field correlators
$\la \fad(x')\fa(x)\ra$ are different depending on the sign of $x'-x$.

categories: cond-mat.stat-mech math-ph math.MP quant-ph


title: Matrix realizations of exceptional superconformal algebras

abstract:
  We give a general construction of realizations of the contact superconformal
algebras $K(2)$ and $\hat{K}'(4)$, and the exceptional superconformal algebra
$CK_6$ as subsuperalgebras of matrices over a Weyl algebra of size $2^N\times
2^N$, where $N = 1, 2$ and $3$. We show that there is no such a realization for
$K(2N)$, if $N\geq 4$.


title:
Instantons and the infrared behavior of the fermion propagator in the
  Schwinger Model

abstract:
  Fermion propagator of the Schwinger Model is revisited from the point of view
of its infrared behavior. The values of anomalous dimensions are found in
arbitrary covariant gauge and in all contributing instanton sectors. In the
case of a gauge invariant, but path dependent propagator, the exponential
dependence, instead of power law one, is established for the special case when
the path is a straight line. The leading behavior is almost identical in any
sector, differing only by the slowly varying, algebraic prefactors. The other
kind of the gauge invariant function, which is the amplitude of the dressed
Dirac fermions, may be reduced, by the appropriate choice of the dressing, to
the gauge variant one, if Landau gauge is imposed.


title: Canonical moments and random spectral measures

abstract:
  We study some connections between the random moment problem and the random
matrix theory. A uniform draw in a space of moments can be lifted into the
spectral probability measure of the pair (A,e) where A is a random matrix from
a classical ensemble and e is a fixed unit vector. This random measure is a
weighted sampling among the eigenvalues of A. We also study the large
deviations properties of this random measure when the dimension of the matrix
grows. The rate function for these large deviations involves the reversed
Kullback information.


title: General class of wormhole geometries in conformal Weyl gravity

abstract:
  In this work, a general class of wormhole geometries in conformal Weyl
gravity is analyzed. A wide variety of exact solutions of asymptotically flat
spacetimes is found, in which the stress energy tensor profile differs
radically from its general relativistic counterpart. In particular, a class of
geometries is constructed that satisfies the energy conditions in the throat
neighborhood, which is in clear contrast to the general relativistic solutions.


title: On a Quaternionic Representation for Sp(4, R)

abstract:
  This work provides a quaternioinc reprsentation for real symplectic matrices
in dimension four, analogous to the pair of unit quaternions representation for
special orthogonal matrices. In the process of finding formulae for this
representation in terms of the entries of the symplectic matrix being thereby
represented, it shows how to compute the polar decomposition of a symplectic
matrix without any need for spectral calculation. The technique just requires
the solution of a simple 2x2 linear system. The work also characterizes
symplectic, positive definite matrices in dimension four, and thus can be used
in applications where the non-compact part of the symplectic group in dimension
four is of utility.


title:
Spitzer observations of the Hyades: Circumstellar debris disks at 625
  Myr of age

abstract:
  We use the Spitzer Space Telescope to search for infrared excess at 24, 70,
and 160 micron due to debris disks around a sample of 45 FGK-type members of
the Hyades cluster. We supplement our observations with archival 24 and 70
micron Spitzer data of an additional 22 FGK-type and 11 A-type Hyades members
in order to provide robust statistics on the incidence of debris disks at 625
Myr of age an era corresponding to the late heavy bombardment in the Solar
System. We find that none of the 67 FGK-type stars in our sample show evidence
for a debris disk, while 2 out of the 11 A-type stars do so. This difference in
debris disk detection rate is likely to be due to a sensitivity bias in favor
of early-type stars. The fractional disk luminosity, L_dust/L*, of the disks
around the two A-type stars is ~4.0E-5, a level that is below the sensitivity
of our observations toward the FGK-type stars. However, our sensitivity limits
for FGK-type stars are able to exclude, at the 2-sigma level, frequencies
higher than 12% and 5% of disks with L_dust/L* > 1.0E-4 and L_dust/L* > 5.0E-4,
respectively. We also use our sensitivity limits and debris disk models to
constrain the maximum mass of dust, as a function of distance from the stars,
that could remain undetected around our targets.


title:
Some relational structures with polynomial growth and their associated
  algebras II: Finite generation

abstract:
  The profile of a relational structure $R$ is the function $\varphi_R$ which
counts for every integer $n$ the number, possibly infinite, $\varphi_R(n)$ of
substructures of $R$ induced on the $n$-element subsets, isomorphic
substructures being identified. If $\varphi_R$ takes only finite values, this
is the Hilbert function of a graded algebra associated with $R$, the age
algebra $A(R)$, introduced by P.~J.~Cameron.
  In a previous paper, we studied the relationship between the properties of a
relational structure and those of their algebra, particularly when the
relational structure $R$ admits a finite monomorphic decomposition. This
setting still encompasses well-studied graded commutative algebras like
invariant rings of finite permutation groups, or the rings of quasi-symmetric
polynomials.
  In this paper, we investigate how far the well know algebraic properties of
those rings extend to age algebras. The main result is a combinatorial
characterization of when the age algebra is finitely generated. In the special
case of tournaments, we show that the age algebra is finitely generated if and
only if the profile is bounded. We explore the Cohen-Macaulay property in the
special case of invariants of permutation groupoids. Finally, we exhibit
sufficient conditions on the relational structure that make naturally the age
algebra into a Hopf algebra.


title: A Locked Orthogonal Tree

abstract:
  We give a counterexample to a conjecture of Poon [Poo06] that any orthogonal
tree in two dimensions can always be flattened by a continuous motion that
preserves edge lengths and avoids self-intersection. We show our example is
locked by extending results on strongly locked self-touching linkages due to
Connelly, Demaine and Rote [CDR02] to allow zero-length edges as defined in
[ADG07], which may be of independent interest. Our results also yield a locked
tree with only eleven edges, which is the smallest known example of a locked
tree.


title: Cosmic (super)string constraints from 21 cm radiation

abstract:
  We calculate the contribution of cosmic strings arising from a phase
transition in the early universe, or cosmic superstrings arising from brane
inflation, to the cosmic 21 cm power spectrum at redshifts z > 30. Future
experiments can exploit this effect to constrain the cosmic string tension Gu
and probe virtually the entire brane inflation model space allowed by current
observations. Although current experiments with a collecting area of ~ 1 km^2
will not provide any useful constraints, future experiments with a collecting
area of 10^4-10^6 km^2 covering the cleanest 10% of the sky can in principle
constrain cosmic strings with tension Gu > 10^(-10) to 10^(-12)
(superstring/phase transition mass scale >10^13 GeV).


title:
Tiger Tales: A Critical Examination of the Tiger's Enclosure at the San
  Francisco Zoo

abstract:
  Given the recent tragedy involving a 350 pound Siberian Tiger and the death
of teenager Carlos Souza Jr., one must ask a fundamental question: Can a tiger
overcome an obstacle that is thirty-three feet away and twelve and a half feet
tall? Are these dimensions sufficient enough to protect the zoo-visitors from a
potential escape and/or attack? To answer these questions we use simple
two-dimensional projectile motion to find the minimum velocity a tiger needs in
order to clear the obstacle. With our results we conclude that it is highly
likely that the tiger was able to leap over the obstacle with ease!


title: Getting Your Eye In: A Bayesian Analysis of Early Dismissals in Cricket

abstract:
  A Bayesian Survival Analysis method is motivated and developed for analysing
sequences of scores made by a batsman in test or first class cricket. In
particular, we expect the presence of an effect whereby the distribution of
scores has more probability near zero than a geometric distribution, due to the
fact that batting is more difficult when the batsman is new at the crease. A
Metropolis-Hastings algorithm is found to be efficient at estimating the
proposed parameters, allowing us to quantify exactly how large this
early-innings effect is, and how long a batsman needs to be at the crease in
order to ``get their eye in''. Applying this model to several modern players
shows that a batsman is typically only playing at about half of their potential
ability when they first arrive at the crease, and gets their eye in
surprisingly quickly. Additionally, some players are more ``robust'' (have a
smaller early-innings effect) than others, which may have implications for
selection policy.


title: The equivalent medium theory within the linear response region

abstract:
  In this paper, we present the equivalent medium theory by using the linear
response theory. It is found that, under the condition of the linear response,
a series of different media with different refractive indices $n_{i}(\omega)$
and lengths $d_{i}$ can be equivalent to an effective medium with the
volume-averaged refractive index $\frac{1}{D}\sum_{i=1}^{N}n_{i}(\omega)d_{i}$
and the total length $D=\sum_{i=1i}^{N}d_{i}$,where $N$ is the number of
different media. Based on this equivalent theory, it is a simple but very
useful method to design the effective medium with any desirable dispersion
properties. As an example, we present a proposal to obtain the enhancement or
reduction of the refractive index without absorption and the large dispersion
without obvious absorption by assembling different linear dispersive gain and
absorptive media.


title: Fully Bayes factors with a generalized g-prior

abstract:
  For the normal linear model variable selection problem, we propose selection
criteria based on a fully Bayes formulation with a generalization of Zellner's
$g$-prior which allows for $p>n$. A special case of the prior formulation is
seen to yield tractable closed forms for marginal densities and Bayes factors
which reveal new model evaluation characteristics of potential interest.


title: Large Spin Entangled Current from a Passive Device

abstract:
  We show that a large entangled current can be produced from a very simple
passive device: a cluster of three resonant quantum dots, tunnel coupled to one
input lead and two output leads. The device can function in a `clean' mode,
when almost all emitted electrons are paired in Bell states, or a `dirty' mode
with a far higher emission rate but a significant portion of non-entangled
electrons. Subsequent charge detection can enhance performance by identifying
the pairs that are most likely to be entangled. The device is robust to
specific choice of system parameters and therefore lends itself to immediate
experimental demonstration. Applications include quantum repeaters and
unconditionally secure interfaces.


title: Asymptotically Plane Wave Spacetimes and their Actions

abstract:
  We propose a definition of asymptotically plane wave spacetimes in vacuum
gravity in terms of the asymptotic falloff of the metric, and discuss the
relation to previously constructed exact solutions. We construct a well-behaved
action principle for such spacetimes, using the formalism developed by Mann and
Marolf. We show that this action is finite on-shell and that the variational
principle is well-defined for solutions of vacuum gravity satisfying our
asymptotically plane wave falloff conditions.


title: Type I planetary migration in a self-gravitating disk

abstract:
  We investigate the tidal interaction between a low-mass planet and a
self-gravitating protoplanetary disk, by means of two-dimensional hydrodynamic
simulations. We first show that considering a planet freely migrating in a disk
without self-gravity leads to a significant overestimate of the migration rate.
The overestimate can reach a factor of two for a disk having three times the
surface density of the minimum mass solar nebula. Unbiased drift rates may be
obtained only by considering a planet and a disk orbiting within the same
gravitational potential. In a second part, the disk self-gravity is taken into
account. We confirm that the disk gravity enhances the differential Lindblad
torque with respect to the situation where neither the planet nor the disk
feels the disk gravity. This enhancement only depends on the Toomre parameter
at the planet location. It is typically one order of magnitude smaller than the
spurious one induced by assuming a planet migrating in a disk without
self-gravity. We confirm that the torque enhancement due to the disk gravity
can be entirely accounted for by a shift of Lindblad resonances, and can be
reproduced by the use of an anisotropic pressure tensor. We do not find any
significant impact of the disk gravity on the corotation torque.


title:
Problems and Solutions in a Graduate Course in Classical Electrodynamics
  (1)

abstract:
  The following is the very first set of the series in 'Problems and Solutions
in a Graduate Course in Classical Electrodynamics'. In each of the sets of the
problems we intend to follow a theme, which not only makes it unique but also
deals with the investigation of a certain class of problems in a thorough and
rigorous manner. Figures are not included.


title: Huge entropy production inside black holes

abstract:
  We show that the entropy created by Ohmic dissipation inside an accreting
charged black hole may exceed the Bekenstein-Hawking entropy by a large factor.
If the black hole subsequently evaporates, radiating only the
Bekenstein-Hawking entropy, then the black hole appears to destroy entropy,
violating the second law of thermodynamics. A companion paper discusses the
implications of this startling result. Bousso's covariant entropy bound is not
violated.