title: The universal shape of economic recession and recovery after a shock

abstract:
  We show that a simple and intuitive three-parameter equation fits remarkably
well the evolution of the gross domestic product (GDP) in current and constant
dollars of many countries during times of recession and recovery. We then argue
that this equation is the response function of the economy to isolated shocks,
hence that it can be used to detect large and small shocks, including those
which do not lead to a recession; we also discuss its predictive power.
Finally, a two-sector toy model of recession and recovery illustrates how the
severity and length of recession depends on the dynamics of transfer rate
between the growing and failing parts of the economy.


title: Expansion of the Universe - Standard Big Bang Model

abstract:
  After a brief introduction to the sixteenth and seventeenth century views of
the Universe and the nineteenth century paradox of Olbers, we start the history
of the cosmic expansion with Hubble's epochal discovery of the recession
velocities of spiral galaxies. By then Einstein's theories of relativity were
well known, but no suitable metric was known. Prior to introducing General
Relativity we embark on a non-chronological derivation of the Robertson-Walker
metric directly from Special Relativity and the Minkowski metric endowed with a
Gaussian curvature. This permits the definition of all relativistic distance
measures needed in observational astronomy. Only thereafter do we come to
General Relativity, and describe some of its consequences: gravitational
lensing, black holes, various tests, and the cornerstone of the standard Big
Bang model, the Friedmann-Lemaitre equations. Going backwards in time towards
Big Bang we first have to trace the thermal history, and then understand the
needs for a cosmic inflation and its predictions. The knowledge of the Big Bang
model is based notably on observations of the Cosmic Microwave Background
Radiation, large scale structures, and the redshifts of distant supernovae.
They tell us that gravitating matter is dominated by a dark and dissipationless
component of unknown composition, and that the observable part of the Universe
exhibits an accelerated expansion representing a fraction of the energy even
larger than gravitating matter.


title: Origin of Low Thermal Conductivity in Nuclear Fuels

abstract:
  Using a novel many-body approach, we report lattice dynamical properties of
UO2 and PuO2 and uncover various contributions to their thermal conductivities.
Via calculated Grueneisen constants, we show that only longitudinal acoustic
modes having large phonon group velocities are efficient heat carriers. Despite
the fact that some optical modes also show their velocities which are extremely
large, they do not participate in the heat transfer due to their unusual
anharmonicity. Ways to improve thermal conductivity in these materials are
discussed.


title: Features of interband absorption in narrow-gap semiconductors

abstract:
  For semiconductors and semimetals possessing a narrow gap between bands with
different parity, the dispersion of the dielectric function is explicitly
evaluated in the infrared region. The imaginary part of the dielectric function
has a plateau above the absorption threshold for the interband electron
transitions. The real part of the dielectric function has a logarithmic
singularity at the threshold. This results in the large contribution into the
dielectric constant for pure semiconductors at low frequencies. For samples
with degenerate carriers, the real part of the dielectric function is divergent
at the absorption threshold. This divergence is smeared with the temperature or
the collision rate.


title:
Investigation of Non Resonant Dot - Cavity Coupling in Two Dimensional
  Photonic Crystal Nanocavities

abstract:
  We study the optical emission from single semiconductor quantum dots coupled
to the optical modes of photonic crystal nanocavities. For dots that are both
spectrally and spatially coupled, auto-correlation measurements reveal
efficient single photon generation, with a drastically reduced lifetime due to
the Purcell-effect. However, the multi-photon emission probability is enhanced
compared to the same QD transition when it is detuned from the cavity mode by
controlled $N_2$-deposition. This indicates the presence of an emission
background that is shown to be related to the dot using photon
cross-correlation spectroscopy. Photon temporal correlations persist even for
large spectral detunings beyond $\Delta\lambda\sim-10 nm$, excluding the
intrinsic QD continuum and phonon mediated processes as being responsible for
the cavity mode emission background. We propose a mechanism based on photon
induced shake up processes in the charged quantum dots, enhanced by the optical
cavity.


title:
Elastocaloric effect associated with the martensitic transition in
  shape-memory alloys

abstract:
  The elastocaloric effect in the vicinity of the martensitic transition of a
Cu-Zn-Al has been studied by inducing the transition by strain or stress
measurements. While transition trajectories show significant differences, the
entropy change associated with the whole transformation (\DeltaSt) is
coincident in both kind of experiments since entropy production is small
compared to \DeltaSt. The values agree with estimations based on the Clausius-
Clapeyron equation. The possibility of using these materials for mechanical
refrigeration is also discussed.


title:
Photometric observations of two type II-P Supernovae: normal SN II-P
  2004A and unusual SN 2004ek

abstract:
  CCD BVRI photometry is presented for type II Supernovae 2004A and 2004ek. SN
2004A is found to be a typical SN II-P, with the shape of the light and color
curves and maximum luminosity closely matching those for SN 1999em. SN 2004ek
shows unusual light curves with long flat plateau in the B band, two peaks in
the V and prominent brightening in the R and I bands, starting about 45 days
past outburst. The brightness decline after the plateau stage is probably quite
slow. The plateau luminosity is about 1.5 mag brighter than average for SN
II-P.


title: A criterion of convergence in the augmented Teichmueller space

abstract:
  We prove a criterion of convergence in the augmented Teichmueller space that
can be phrased in terms of convergence of the hyperbolic metrics or of
quasiconformal convergence away from the nodes.


title:
Absence of Hole Confinement in Transition Metal Oxides with Orbital
  Degeneracy

abstract:
  We investigate the spectral properties of a hole moving in a two-dimensional
Hubbard model for strongly correlated t_2g electrons. Although superexchange
interactions are Ising-like, a quasi-one-dimensional coherent hole motion
arises due to effective three-site terms. This mechanism is fundamentally
different from the hole motion via quantum fluctuations in the conventional
spin model with SU(2) symmetry. The orbital model describes also propagation of
a hole in some e_g compounds, and we argue that orbital degeneracy alone does
not lead to hole self-localization.


title:
Throughput-Delay Trade-off for Hierarchical Cooperation in Ad Hoc
  Wireless Networks

abstract:
  Hierarchical cooperation has recently been shown to achieve better throughput
scaling than classical multihop schemes under certain assumptions on the
channel model in static wireless networks. However, the end-to-end delay of
this scheme turns out to be significantly larger than those of multihop
schemes. A modification of the scheme is proposed here that achieves a
throughput-delay trade-off $D(n)=(\log n)^2 T(n)$ for T(n) between
$\Theta(\sqrt{n}/\log n)$ and $\Theta(n/\log n)$, where D(n) and T(n) are
respectively the average delay per bit and the aggregate throughput in a
network of n nodes. This trade-off complements the previous results of El Gamal
et al., which show that the throughput-delay trade-off for multihop schemes is
given by D(n)=T(n) where T(n) lies between $\Theta(1)$ and $\Theta(\sqrt{n})$.
  Meanwhile, the present paper considers the network multiple-access problem,
which may be of interest in its own right.


title:
Influence of an inner disc on the orbital evolution of massive planets
  migrating in resonance

abstract:
  The formation of resonant pairs of planets in exoplanetary systems involves
planetary migration in the protoplanetary disc. After a resonant capture, the
subsequent migration in this configuration leads to a large increase of
planetary eccentricities if no damping mechanism is applied. This has led to
the conclusion that the migration of resonant planetary systems cannot occur
over large radial distances and has to be terminated sufficiently rapidly
through disc dissipation.
  In this study, we investigate whether the presence of an inner disc might
supply an eccentricity damping of the inner planet, and if this effect could
explain the observed eccentricities in some systems. To investigate the
influence of an inner disc, we first compute hydrodynamic simulations of giant
planets orbiting with a given eccentricity around an inner gas disc, and
measure the effect of the latter on the planetary orbital parameters. We then
perform detailed long term calculations of the GJ 876 system. We also run
N-body simulations with artificial forces on the planets mimicking the effects
of the inner and outer discs.
  We find that the influence of the inner disc can not be neglected, and that
it might be responsible for the observed eccentricities. In particular, we
reproduce quite well the orbital parameters of a few systems engaged in 2:1
mean motion resonances: GJ 876, HD 73526, HD 82943 and HD 128311. Finally, we
derive analytically the effect that the inner disc should have on the inner
planet to reach a specific orbital configuration with a given damping effect of
the outer disc on the outer planet.


title: Combining Expert Advice Efficiently

abstract:
  We show how models for prediction with expert advice can be defined concisely
and clearly using hidden Markov models (HMMs); standard HMM algorithms can then
be used to efficiently calculate, among other things, how the expert
predictions should be weighted according to the model. We cast many existing
models as HMMs and recover the best known running times in each case. We also
describe two new models: the switch distribution, which was recently developed
to improve Bayesian/Minimum Description Length model selection, and a new
generalisation of the fixed share algorithm based on run-length coding. We give
loss bounds for all models and shed new light on their relationships.


title: Symmetry breaking of gauge theories down to Abelian sub-groups

abstract:
  I re-derive the lowest order effective Lagrangian for electro-weak symmetry
breaking without the use of Goldstone's theorem for spontaneously broken global
symmetries and without the assumption of a custodial symmetry. I consider the
breaking of a local symmetry with gauge group G down to an Abelian sub-group K
and construct a gauge-invariant functional with one free parameter v, such that
v=0 corresponds to a gauge theory with gauge group G, while v --> infinity
corresponds to a gauge theory with gauge group K.


title:
Probing the cosmic acceleration history and the properties of dark
  energy from the ESSENCE supernova data with a model independent method

abstract:
  With a model independent method the expansion history $H(z)$, the
deceleration parameter $q(z)$ of the universe and the equation of state $w(z)$
for the dark energy are reconstructed directly from the 192 Sne Ia data points,
which contain the new ESSENCE Sne Ia data and the high redshift Sne Ia data. We
find that the evolving properties of $q(z)$ and $w(z)$ reconstructed from the
192 Sne Ia data seem to be weaker than that obtained from the Gold set, but
stronger than that from the SNLS set. With a combination of the 192 Sne Ia and
BAO data, a tight constraint on $\Omega_{m0}$ is obtained. At the $1\sigma$
confidence level $\Omega_{m0}=0.278^{+0.024}_{-0.023}$, which is highly
consistent with that from the Gold+BAO and SNLS+BAO.


title:
Thermal nature of de Sitter spacetime and spontaneous excitation of
  atoms

abstract:
  We consider, in de Sitter spacetime, both freely falling and static two-level
atoms in interaction with a conformally coupled massless scalar field in the de
Sitter-invariant vacuum, and separately calculate the contributions of vacuum
fluctuations and radiation reaction to the atom's spontaneous excitation rate.
We find that spontaneous excitations occur even for the freely falling atom as
if there is a thermal bath of radiation at the Gibbons-Hawking temperature and
we thus recover, in a different physical context, the results of Gibbons and
Hawking that reveals the thermal nature of de Sitter spacetime. Similarly, for
the case of the static atom, our results show that the atom also perceives a
thermal bath which now arises as a result of the intrinsic thermal nature of de
Sitter spacetime and the Unruh effect associated with the inherent acceleration
of the atom.


title: Bipartite quantum systems: on the realignment criterion and beyond

abstract:
  Inspired by the `computable cross norm' or `realignment' criterion, we
propose a new point of view about the characterization of the states of
bipartite quantum systems. We consider a Schmidt decomposition of a bipartite
density operator. The corresponding Schmidt coefficients, or the associated
symmetric polynomials, are regarded as quantities that can be used to
characterize bipartite quantum states. In particular, starting from the
realignment criterion, a family of necessary conditions for the separability of
bipartite quantum states is derived. We conjecture that these conditions, which
are weaker than the parent criterion, can be strengthened in such a way to
obtain a new family of criteria that are independent of the original one. This
conjecture is supported by numerical examples for the low dimensional cases.
These ideas can be applied to the study of quantum channels, leading to a
relation between the rate of contraction of a map and its ability to preserve
entanglement.


title: Derivative sources in lattice spectroscopy of excited light-quark mesons

abstract:
  We construct efficient interpolating fields for lattice spectroscopy of
mesons by applying covariant derivatives on Jacobi smeared quark sources. These
interpolators are tested in a quenched calculation of excited mesons based on
the variational method. We present results for pseudoscalar, scalar, vector and
pseudovector mesons.


title:
The effect of radiation pressure on virial black hole mass estimates and
  the case of Narrow Line Seyfert 1 galaxies

abstract:
  We consider the effect of radiation pressure from ionizing photons on black
hole (BH) mass estimates based on the application of the virial theorem to
broad emission lines in AGN spectra. BH masses based only on the virial product
V^2R and neglecting the effect of radiation pressure can be severely
underestimated especially in objects close to the Eddington limit. We provide
an empirical calibration of the correction for radiation pressure and we show
that it is consistent with a simple physical model in which BLR clouds are
optically thick to ionizing radiation and have average column densities of
NH~10^23 cm^-2. This value is remarkably similar to what is required in
standard BLR photoionization models to explain observed spectra. With the
inclusion of radiation pressure the discrepancy between virial BH masses based
on single epoch spectra and on reverberation mapping data drops from 0.4 to 0.2
dex rms. The use of single epoch observations as surrogates of reverberation
mapping campaigns can thus provide more accurate BH masses than previously
thought. Finally, we show that Narrow Line Seyfert 1 (NLS1) galaxies have
apparently low BH masses because they are radiating close to their Eddington
limit. After the radiation pressure correction, NLS1 galaxies have BH masses
similar to other broad line AGNs and follow the same MBH-sigma/L relations as
other active and normal galaxies. Radiation forces arising from ionizing photon
momentum deposition constitute an important physical effect which must be taken
into account when computing virial BH masses.


title:
A Far Ultraviolet Archival Study of Cataclysmic Variables: I. FUSE and
  HST/STIS Spectra of the Exposed White Dwarf in Dwarf Nova Systems

abstract:
  We present a synthetic spectral analysis of Far Ultraviolet Spectroscopic
Explorer (FUSE) and Hubble Space Telescope/Space Telescope Imaging Spectrograph
(HST/STIS) spectra of 5 dwarf novae above and below the period gap during
quiescence. We use our synthetic spectral code, including options for the
treatment of the hydrogen quasi-molecular satellite lines (for low temperature
stellar atmospheres), NLTE approximation (for high temperature stellar
atmospheres), and for one system (RU Peg) we model the interstellar medium
(ISM) molecular and atomic hydrogen lines. In all the systems presented here
the FUV flux continuum is due to the WD. These spectra also exhibit some broad
emission lines. In this work we confirm some of the previous FUV analysis
results but we also present new results. For 4 systems we combine the FUSE and
STIS spectra to cover a larger wavelength range and to improve the spectral
fit. This work is part of our broader HST archival research program, in which
we aim to provide accurate system parameters for cataclysmic variables above
and below the period gap by combining FUSE and HST FUV spectra.


title: LISACode : A scientific simulator of LISA

abstract:
  A new LISA simulator (LISACode) is presented. Its ambition is to achieve a
new degree of sophistication allowing to map, as closely as possible, the
impact of the different sub-systems on the measurements. LISACode is not a
detailed simulator at the engineering level but rather a tool whose purpose is
to bridge the gap between the basic principles of LISA and a future,
sophisticated end-to-end simulator. This is achieved by introducing, in a
realistic manner, most of the ingredients that will influence LISA's
sensitivity as well as the application of TDI combinations. Many user-defined
parameters allow the code to study different configurations of LISA thus
helping to finalize the definition of the detector. Another important use of
LISACode is in generating time series for data analysis developments.


title:
Bimodality, prion aggregates infectivity and prediction of strain
  phenomenon

abstract:
  We consider a model for the polymerization (fragmentation) process involved
in infectious prion self-replication and study both its dynamics and non-zero
steady state. We address several issues. Firstly, we give conditions leading to
size repartitions of PrPsc aggregates that exhibit bimodal distributions, as
indicated by recent experimental studies of prion aggregates distribution.
Secondly, we show stability results for this steady state for general
coefficients where reduction to a system of differential equations is not
possible. We use a duality method based on recent ideas developed for
population models. These results underline the potential influence of the
amyloid precursor production rate in promoting amyloidogenic diseases. Finally,
we numerically investigate the influence of different parameters of the model
on PrPsc accumulation kinetics, in the aim to study specific features of prion
strains.


title:
Use of cumulants to quantify uncertainties in the HBT measurements of
  the homogeneity regions

abstract:
  Let us denote p(x|K) the space density of the points where identical
particles of some kind, e.g. pi+ mesons, with momentum K are produced. When
using the HBT method to determine p(x|K) one encounters ambiguities. We show
that these ambiguities do not affect the even cumulants of the distribution
p(x|K). In particular, the HBT radii of the homogeneity regions, which are
given by the second order cumulants, and the distribution of distances between
the pairs of production points for particles with momentum K can be reliably
measured. The odd cumulants are ambiguous. The are, however, correlated. In
particular, when the average position <x>(K) is known as a function of K there
is no further ambiguity.


title: The Accretion Disk Wind in the Black Hole GRO J1655-40

abstract:
  We report on simultaneous Chandra/HETGS and RXTE observations of the
transient stellar-mass black hole GRO J1655-40, made during its 2005 outburst.
Chandra reveals a line-rich X-ray absorption spectrum consistent with a disk
wind. Prior modeling of the spectrum suggested that the wind may be
magnetically driven, potentially providing insights into the nature of disk
accretion onto black holes. In this paper, we present results obtained with new
models for this spectrum, generated using three independent photoionization
codes: XSTAR, Cloudy, and our own code. Fits to the spectrum in particular
narrow wavelength ranges, in evenly spaced wavelength slices, and across a
broad wavelength band all strongly prefer a combination of high density, high
ionization, and small inner radius. Indeed, the results obtained from all three
codes require a wind that originates more than 10 times closer to the black
hole and carrying a mass flux that is on the order of 1000 times higher than
predicted by thermal driving models. If seminal work on thermally-driven disk
winds is robust, magnetic forces may play a role in driving the disk wind in
GRO J1655-40. However, even these modeling efforts must be regarded as crude
given the complexity of the spectra. We discuss these results in the context of
accretion flows in black holes and other compact objects.


title: Kolmogorov Complexity Theory over the Reals

abstract:
  Kolmogorov Complexity constitutes an integral part of computability theory,
information theory, and computational complexity theory -- in the discrete
setting of bits and Turing machines. Over real numbers, on the other hand, the
BSS-machine (aka real-RAM) has been established as a major model of
computation. This real realm has turned out to exhibit natural counterparts to
many notions and results in classical complexity and recursion theory; although
usually with considerably different proofs. The present work investigates
similarities and differences between discrete and real Kolmogorov Complexity as
introduced by Montana and Pardo (1998).


title:
The influence of localized states charging on 1/f^{\alpha} tunneling
  current noise spectrum

abstract:
  We report the results of theoretical investigations of low frequency
tunneling current noise spectra component (1/f^{\alpha}). Localized states of
individual impurity atoms play the key role in low frequency tunneling current
noise formation. It is found that switching "on" and "off" of Coulomb
interaction of conduction electrons with one or two charged localized states
results in power law singularity of low-frequency tunneling current noise
spectrum 1/f^{\alpha}. Power law exponent in different low frequency ranges
depends on the relative values of Coulomb interaction of conduction electrons
with different charged impurities.


title: Vacancy induced magnetism in graphene and graphene ribbons

abstract:
  We address the electronic structure and magnetic properties of vacancies and
voids both in graphene and graphene ribbons. Using a mean field Hubbard model,
we study the appearance of magnetic textures associated to removing a single
atom (vacancy) and multiple adjacent atoms (voids) as well as the magnetic
interactions between them. A simple set of rules, based upon Lieb theorem, link
the atomic structure and the spatial arrangement of the defects to the emerging
magnetic order. The total spin $S$ of a given defect depends on its sublattice
imbalance, but some defects with S=0 can still have local magnetic moments. The
sublattice imbalance also determines whether the defects interact
ferromagnetically or antiferromagnetically with one another and the range of
these magnetic interactions is studied in some simple cases. We find that in
semiconducting armchair ribbons and two-dimensional graphene without global
sublattice imbalance there is maximum defect density above which local
magnetization disappears. Interestingly, the electronic properties of
semiconducting graphene ribbons with uncoupled local moments are very similar
to those of diluted magnetic semiconductors, presenting giant Zeeman splitting.


title:
Renormalizability and Phenomenology of theta-expanded Noncommutative
  Gauge Field Theory

abstract:
  In this article we consider theta-expanded noncommutative gauge field theory,
constructed at the first order in noncommutative parameter theta, as an
effective, anomaly free theory, with one-loop renormalizable gauge sector.
Related phenomenology with emphasis on the standard model forbidden decays, is
discussed. Experimental possibilities of Z -> gamma gamma decay are analyzed
and a firm bound to the scale of the noncommutativity parameter is set around
few TeV's.


title: Towards a 1% measurement of the Lense-Thirring effect with LARES?

abstract:
  After the recent approval by the Italian Space Agency (ASI) of the LARES
mission, which will be launched at the end of 2008 by a VEGA rocket to measure
the general relativistic gravitomagnetic Lense-Thirring effect by combining
LARES data with those of the existing LAGEOS and LAGEOS II satellites, it is of
the utmost importance to assess if the claimed accuracy \lesssim 1% will be
realistically obtainable. A major source of systematic error is the
mismodelling \delta J_L in the static part of the even zonal harmonic
coefficients J_L, L=2,4,6,.. of the multipolar expansion of the classical part
of the terrestrial gravitational potential; such a bias crucially depends on
the orbital configuration of LARES. If for \delta J_L the difference between
the best estimates of different Earth's gravity solutions from the dedicated
GRACE mission is conservatively taken instead of optimistically considering the
statistical covariance sigmas of each model separately, as done so far in
literature, it turns out that, since LARES will be likely launched in a
low-orbit (semimajor axis a\lesssim 7600 km), the bias due to the geopotential
may be up to ten times larger than what claimed, according to a calculation up
to degree L=20. Taking into account also the even zonal harmonics with L>20, as
required by the relatively low altitude of LARES, may further degrade the total
accuracy. Should a nearly polar configuration (inclination to the Earth's
equator i\approx 90 deg) be finally implemented, also other perturbations would
come into play, further corrupting the measurement of the Lense-Thirring
effect. The orbital configuration of LARES may also have some consequences in
terms of non-gravitational perturbations and measurement errors.

categories: gr-qc astro-ph physics.geo-ph physics.space-ph


title:
On finiteness of the sum of negative eigenvalues of Schroedinger
  operators

abstract:
  We prove conditions on potentials which imply that the sum of the negative
eigenvalues of the Schroeodinger operator is finite. We use a method for
bounding eigenvalues based on estimates of the Hilbert-Schmidt norm of
semigroup differences and on complex analysis


title:
Constraints on resonant-trapping for two planets embedded in a
  protoplanetary disc

abstract:
  We investigate the evolution of two-planet systems embedded in a
protoplanetary disc, which are composed of a Jupiter-mass planet plus another
body located further out in the disc. We consider outermost planets with masses
ranging from 10 earth masses to 1 M_J. We also examine the case of outermost
bodies with masses < 10 earth masses (M_E). Differential migration of the
planets due to disc torques leads to different evolution outcomes depending on
the mass of the outer protoplanet. For planets with mass < 3.5 M_E the type II
migration rate of the giant exceeds the type I migration rate of the outer
body, resulting in divergent migration. Outer bodies with masses in the range
3.5 < m_o < 20 M_E become trapped at the edge of the gap formed by the giant
planet, because of corotation torques. Higher mass planets are captured into
resonance with the inner planet. If 30 < m_o < 40 M_E or m_o=1 M_J, then the
2:1 resonance is established. If 80 < m_o < 100 M_E, the 3:2 resonance is
favoured. Simulations of gas-accreting protoplanets of mass m_o > 20 M_E,
trapped initially at the edge of the gap, or in the 2:1 resonance, also result
in eventual capture in the 3:2 resonance as the planet mass grows to become
close to the mass of Saturn. Our results suggest that there is a theoretical
lower limit to the mass of an outer planet that can be captured into resonance
with an inner Jovian planet, which is relevant to observations of extrasolar
multiplanet systems. Furthermore, capture of a Saturn-like planet into the 3:2
resonance with a Jupiter-like planet is a very robust outcome of simulations.
This result is relevant to recent scenarios of early Solar System evolution
which require Saturn to have existed interior to the 2:1 resonance with Jupiter
prior to the onset of the Late Heavy Bombardment.


title:
Extragalactic jets with helical magnetic fields: relativistic MHD
  simulations

abstract:
  Extragalactic jets are inferred to harbor dynamically important, organized
magnetic fields which presumably aid in the collimation of the relativistic jet
flows. We here explore by means of grid-adaptive, high resolution numerical
simulations the morphology of AGN jets pervaded by helical field and flow
topologies. We concentrate on morphological features of the bow shock and the
jet beam behind the Mach disk, for various jet Lorentz factors and magnetic
field helicities. We investigate the influence of helical magnetic fields on
jet beam propagation in overdense external medium. We use the AMRVAC code,
employing a novel hybrid block-based AMR strategy, to compute ideal plasma
dynamics in special relativity. The helicity of the beam magnetic field is
effectively transported down the beam, with compression zones in between
diagonal internal cross-shocks showing stronger toroidal field regions. In
comparison with equivalent low-relativistic jets which get surrounded by
cocoons with vortical backflows filled by mainly toroidal field, the high speed
jets demonstrate only localized, strong toroidal field zones within the
backflow vortical structures. We find evidence for a more poloidal, straight
field layer, compressed between jet beam and backflows. This layer decreases
the destabilizing influence of the backflow on the jet beam. In all cases, the
jet beam contains rich cross-shock patterns, across which part of the kinetic
energy gets transferred. For the high speed reference jet considered here,
significant jet deceleration only occurs beyond distances exceeding ${\cal
O}(100 R_j)$, as the axial flow can reaccelerate downstream to the internal
cross-shocks. This reacceleration is magnetically aided, due to field
compression across the internal shocks which pinch the flow.


title: Free involutions on S^1xS^n

abstract:
  Topological free involutions on S^1xS^n are classified up to conjugation. As
a byproduct we obtain a new computation of the group of concordance classes of
homeomorphisms of the projective space RP^n.


title: A Multi-wavelength Study of the Massive Star-forming Region S87

abstract:
  This article presents a multi-wavelength study towards S87, based on a
dataset of submillimeter/far-/mid-infrared (sub-mm/FIR/MIR) images and
molecular line maps. The sub-mm continuum emission measured with JCMT/SCUBA
reveals three individual clumps, namely, SMM1, SMM2, and SMM3. The MIR/FIR
images obtained by the Spitzer Space Telescope indicate that both SMM1 and SMM3
harbor point sources. The J=1-0 transitions of CO, 13CO, C18O, and HCO+,
measured with the 13.7m telescope of the Purple Mountain Observatory, exhibit
asymmetric line profiles. Our analysis of spectral energy distributions (SEDs)
shows that all of the three sub-mm clumps are massive (110--210 $M_{\odot}$),
with average dust temperatures in the range ~20--40K. A multi-wavelength
comparison convinces us that the asymmetric profiles of molecular lines should
result from two clouds at slightly different velocities, and it further
confirms that the star-forming activity in SMM1 is stimulated by a cloud-cloud
collision. The stellar contents and SEDs suggest that SMM1 and SMM3 are
high-mass and intermediate-mass star-forming sites respectively. However, SMM2
has no counterpart downwards 70 micron, which is likely to be a cold high-mass
starless core. These results, as mentioned above, expose multiple phases of
star formation in S87.


title: Classical and quantum gravity of brane black holes

abstract:
  We test the holographic conjecture for brane black holes: that a full
classical 5D solution will correspond to a quantum corrected 4D black hole. We
show that a Schwarzschild-AdS black string in the bulk can be consistently
interpreted as a quantum-corrected black hole on the brane, but the form of the
quantum corrections is unlike what we would expect. The stress tensor extracted
from the bulk solution does not have a thermal component corresponding to
Hawking radiation outside the black hole. We compare this strong coupling
prediction to a weak coupling calculation to study the differences in detail.
We comment on implications for asymptotically flat black holes and for black
holes localised in the extra dimension.


title: Miniscule representations, Gauss sum and modular invariance

abstract:
  After explaining the concepts of Langlands dual and miniscule
representations, we define an analog of the Gauss sum for any compact, simple
Lie group with a simply laced Lie algebra. We then show a reciprocity property
when a Lie group is exchanged with its Langlands dual. We also explore the
relation with theta functions and modular transformations. In the non-simply
laced case, we construct a unitary representation of the Hecke group which
involves interesting new phase factors.


title: Spiky strings, light-like Wilson loops and pp-wave anomaly

abstract:
  We consider rigid rotating closed strings with spikes in AdS5 dual to certain
higher twist operators in N=4 SYM theory. In the limit of large spin when the
spikes reach the boundary of AdS5, the solutions with different numbers of
spikes are related by conformal transformations, implying that their energy is
determined by the same function of the `t Hooft coupling f(lambda) that appears
in the anomalous dimension of twist 2 operators or in the cusp anomaly. In the
limit when the number of spikes goes to infinity, we find an equivalent
description in terms of a string moving in an AdS pp-wave background. From the
boundary theory point of view, the corresponding description is based on the
gauge theory living in a 4d pp-wave space. Then, considering a charge moving at
the speed of light, or a null Wilson line, we find that the integrated energy
momentum tensor has a logarithmic UV divergence whose coefficient we call the
"pp-wave anomaly". The AdS/CFT correspondence implies that, for N=4 SYM, this
pp-wave anomaly should have the same value as the cusp anomaly. We verify this
at lowest order in SYM perturbation theory. As a side result of our string
theory analysis, we find new open string solutions in the Poincare patch of the
standard AdS space which end on a light-like Wilson line and also in two
parallel light-like Wilson lines at the boundary.


title: Invariant Killing spinors in 11D and type II supergravities

abstract:
  We present all isotropy groups and associated $\Sigma$ groups, up to discrete
identifications of the component connected to the identity, of spinors of
eleven-dimensional and type II supergravities. The $\Sigma$ groups are products
of a Spin group and an R-symmetry group of a suitable lower dimensional
supergravity theory. Using the case of SU(4)-invariant spinors as a paradigm,
we demonstrate that the $\Sigma$ groups, and so the R-symmetry groups of
lower-dimensional supergravity theories arising from compactifications, have
disconnected components. These lead to discrete symmetry groups reminiscent of
R-parity. We examine the role of disconnected components of the $\Sigma$ groups
in the choice of Killing spinor representatives and in the context of
compactifications.


title: Dark Matter Accretion into Supermassive Black Holes

abstract:
  The relativistic accretion rate of dark matter by a black hole is revisited.
Under the assumption that the phase space density indicator,
$Q=\rho_{\infty}/\sigma^3_{\infty}$, remains constant during the inflow, the
derived accretion rate can be higher up to five orders of magnitude than the
classical accretion formula, valid for non-relativistic and non-interacting
particles, when typical dark halo conditions are considered. For these typical
conditions, the critical point of the flow is located at distances of about
30-150 times the horizon radius. Application of our results to black hole seeds
hosted by halos issued from cosmological simulations indicate that dark matter
contributes to no more than ~10% of the total accreted mass, confirming that
the bolometric quasar luminosity is related to the baryonic accretion history
of the black hole.


title: Weak Measurements with Entangled Probes

abstract:
  Encoding the imaginary part of a weak value onto an initially entangled probe
can modify its entanglement content - provided the probe observable can
distinguish between states of different entropies. Apart from fundamental
interest, this result illustrates the utility of the imaginary weak value as a
calculational tool in certain entanglement concentration protocols.


title: Light-induced magnetization precession in GaMnAs

abstract:
  We report dynamics of the transient polar Kerr rotation (KR) and of the
transient reflectivity induced by femtosecond laser pulses in ferromagnetic
(Ga,Mn)As with no external magnetic field applied. It is shown that the
measured KR signal consist of several different contributions, among which only
the oscillatory signal is directly connected with the ferromagnetic order in
(Ga,Mn)As. The origin of the light-induced magnetization precession is
discussed and the magnetization precession damping (Gilbert damping) is found
to be strongly influenced by annealing of the sample.


title: Generalized Andr\'{e}-Quillen Cohomology

abstract:
  We explain how the approach of Andre and Quillen to defining cohomology and
homology as suitable derived functors extends to generalized (co)homology
theories, and how this identification may be used to study the relationship
between them.
  As a side benefit, we clarify exactly what assumptions on an (algebraic)
category are needed in order for the approach of Beck and Andre-Quillen to
work.
  We also show how the description may be applied to construct universal
coefficient and reverse Adams spectral sequences.


title:
Blocking Sets in the complement of hyperplane arrangements in projective
  space

abstract:
  It is well know that the theory of minimal blocking sets is studied by
several author. Another theory which is also studied by a large number of
researchers is the theory of hyperplane arrangements. We can remark that the
affine space $AG(n,q)$ is the complement of the line at infinity in $PG(n,q)$.
Then $AG(n,q)$ can be regarded as the complement of an hyperplane arrangement
in $PG(n,q)$! Therefore the study of blocking sets in the affine space
$AG(n,q)$ is simply the study of blocking sets in the complement of a finite
arrangement in $PG(n,q)$. In this paper the author generalizes this remark
starting to study the problem of existence of blocking sets in the complement
of a given hyperplane arrangement in $PG(n,q)$. As an example she solves the
problem for the case of braid arrangement. Moreover she poses significant
questions on this new and interesting problem.


title:
Non-Markovian decoherence of localized nanotube excitons by acoustic
  phonons

abstract:
  We demonstrate that electron-phonon interaction in quantum dots embedded in
one-dimensional systems leads to pronounced, non-Markovian decoherence of
optical transitions. The experiments we present focus on the lineshape of
photoluminescence from low-temperature axially localized carbon nanotube
excitons. The independent boson model that we use to model the phonon
interactions reproduces with very high accuracy the broad and asymmetric
emission lines and the weak red-detuned radial breathing mode replicas observed
in the experiments. The intrinsic phonon-induced pure-dephasing of the
zero-phonon line is two orders of magnitude larger than the lifetime broadening
and is a hallmark of the reduced dimensionality of the phonon bath. The
non-Markovian nature of this decoherence mechanism may have adverse
consequences for applications of one-dimensional systems in quantum information
processing.


title: $S$-duality in Vafa-Witten theory for non-simply laced gauge groups

abstract:
  Vafa-Witten theory is a twisted N=4 supersymmetric gauge theory whose
partition functions are the generating functions of the Euler number of
instanton moduli spaces. In this paper, we recall quantum gauge theory with
discrete electric and magnetic fluxes and review the main results of
Vafa-Witten theory when the gauge group is simply laced. Based on the
transformations of theta functions and their appearance in the blow-up
formulae, we propose explicit transformations of the partition functions under
the Hecke group when the gauge group is non-simply laced. We provide various
evidences and consistency checks.


title: New Brown Dwarf Disks in the TW Hydrae Association

abstract:
  In our analysis of {\it Spitzer}/IRS archival data on the stellar and
sub-stellar members of the TW Hydrae Association (TWA), we have discovered two
new brown dwarf disks: a flat optically thick disk around SSSPM J1102-3431
(SSSPM 1102), and a transition disk around 2MASS J1139511-315921 (2M1139). The
disk structure for SSSPM 1102 is found to be very similar to the known brown
dwarf disk 2MASSW J1207334-393254 (2M1207), with excess emission observed at
wavelengths as short as 5 $\micron$. 2M1139 shows no excess emission shortward
of $\sim$20 $\micron$, but flares up at longer wavelengths, and is the first
transition disk detected among the sub-stellar members of TWA. We also report
on the {\it Spitzer}/70 $\micron$ observations, and the presence of a weak {\it
absorption} 10 $\micron$ silicate feature for 2M1207. The absorption can be
attributed to a close to edge-on disk at a 75$\degr$ inclination. The 10
$\micron$ spectrum for 2M1207 shows crystalline forsterite features, with a
peak in absorption near 11.3 $\micron$. No silicate absorption/emission is
observed towards SSSPM 1102. While only 6 out of 25 stellar members show excess
emission at these mid-infrared wavelengths, {\it all} of the TWA brown dwarfs
that have been observed so far with {\it Spitzer} show signs of disks around
them, resulting in a disk fraction of at least 60%. This is a considerable
fraction at a relatively older age of $\sim$10 Myr. A comparison with younger
clusters indicates that by the age of the TWA ($\sim$10 Myr), the disk fraction
for brown dwarfs has not decreased, whereas it drops by a factor of $\sim$2 for
the higher mass stars. This suggests longer disk decay time scales for brown
dwarfs compared to higher mass stars.


title: Solution non universelle pour le probl\`eme KV-78

abstract:
  In 78' M. Kashiwara and Vergne conjectured some property on the
Campbell-Hausdorff series in such way a trace formula is satisfied. They
proposed an explicit solution in the case of solvable Lie algebras. In this
note we prove that this "solvable solution" is not universal. Our method is
based on computer calculation. Furthermore our programs prove up to degree 16,
Drinfeld's Lie algebra $\mathfrak{grt}_1$ coincides with the Lie algebra
$\hat{kv_2}$ defined in \cite{AT}.


title: FINE: Fisher Information Non-parametric Embedding

abstract:
  We consider the problems of clustering, classification, and visualization of
high-dimensional data when no straightforward Euclidean representation exists.
Typically, these tasks are performed by first reducing the high-dimensional
data to some lower dimensional Euclidean space, as many manifold learning
methods have been developed for this task. In many practical problems however,
the assumption of a Euclidean manifold cannot be justified. In these cases, a
more appropriate assumption would be that the data lies on a statistical
manifold, or a manifold of probability density functions (PDFs). In this paper
we propose using the properties of information geometry in order to define
similarities between data sets using the Fisher information metric. We will
show this metric can be approximated using entirely non-parametric methods, as
the parameterization of the manifold is generally unknown. Furthermore, by
using multi-dimensional scaling methods, we are able to embed the corresponding
PDFs into a low-dimensional Euclidean space. This not only allows for
classification of the data, but also visualization of the manifold. As a whole,
we refer to our framework as Fisher Information Non-parametric Embedding
(FINE), and illustrate its uses on a variety of practical problems, including
bio-medical applications and document classification.


title: Signal-to-noise ratio of phase sensing telescope interferometers

abstract:
  This paper is the third part of a trilogy dealing with the principles,
performance and limitations of what I named "Telescope-Interferometers" (TIs).
The basic idea consists in transforming one telescope into a Wavefront Error
(WFE) sensing device. This can be achieved in two different ways, namely the
off axis and phase-shifting TIs. In both cases the Point-Spread Function (PSF)
measured in the focal plane of the telescope carries information about the
transmitted WFE, which is retrieved by fast and simple algorithms suitable to
an Adaptive Optics (AO) regime. Herein are evaluated the uncertainties of both
types of TIs, in terms of noise and systematic errors. Numerical models are
developed in order to establish the dependence of driving parameters such as
useful spectral range, angular size of the observed star, or detector noise on
the total WFE measurement error. The latter is found particularly sensitive to
photon noise, which rapidly governs the achieved accuracy for telescope
diameters higher than 10 m. We study a few practical examples, showing that TI
method is applicable to AO systems on telescope diameters ranging from 10 to 50
m, depending on seeing conditions and magnitude of the observed stars. We also
discuss the case of a space-borne coronagraph where TI technique provides high
sampling of the input WFE map.


title: Magnetospheric accretion on the T Tauri star BP Tauri

abstract:
  From observations collected with the ESPaDOnS and NARVAL spectropolarimeters,
we report the detection of Zeeman signatures on the classical T Tauri star BP
Tau. Circular polarisation signatures in photospheric lines and in narrow
emission lines tracing magnetospheric accretion are monitored throughout most
of the rotation cycle of BP Tau at two different epochs in 2006. We observe
that rotational modulation dominates the temporal variations of both
unpolarised and circularly polarised spectral proxies tracing the photosphere
and the footpoints of accretion funnels.
  From the complete data sets at each epoch, we reconstruct the large-scale
magnetic topology and the location of accretion spots at the surface of BP Tau
using tomographic imaging. We find that the field of BP Tau involves a 1.2 kG
dipole and 1.6 kG octupole, both slightly tilted with respect to the rotation
axis. Accretion spots coincide with the two main magnetic poles at high
latitudes and overlap with dark photospheric spots; they cover about 2% of the
stellar surface. The strong mainly-axisymmetric poloidal field of BP Tau is
very reminiscent of magnetic topologies of fully-convective dwarfs. It suggests
that magnetic fields of fully-convective cTTSs such as BP Tau are likely not
fossil remants, but rather result from vigorous dynamo action operating within
the bulk of their convective zones.
  Preliminary modelling suggests that the magnetosphere of BP Tau extends to
distances of at least 4 R* to ensure that accretion spots are located at high
latitudes, and is not blown open close to the surface by a putative stellar
wind. It apparently succeeds in coupling to the accretion disc as far out as
the corotation radius, and could possibly explain the slow rotation of BP Tau.


title: Uniform continuity over locally compact quantum groups

abstract:
  We define, for a locally compact quantum group $G$ in the sense of
Kustermans--Vaes, the space of $LUC(G)$ of left uniformly continuous elements
in $L^\infty(G)$. This definition covers both the usual left uniformly
continuous functions on a locally compact group and Granirer's uniformly
continuous functionals on the Fourier algebra. We show that $LUC(G)$ is an
operator system containing the $C^*$-algebra $C_0(G)$ and contained in its
multiplier algebra $M(C_0(G))$. We use this to partially answer an open problem
by Bedos--Tuset: if $G$ is co-amenable, then the existence of a left invariant
mean on $M(C_0(G))$ is sufficient for $G$ to be amenable. Furthermore, we study
the space $WAP(G)$ of weakly almost periodic elements of $L^\infty(G)$: it is a
closed operator system in $L^\infty(G)$ containing $C_0(G)$ and--for
co-amenable $G$--contained in $LUC(G)$. Finally, we show that--under certain
conditions, which are always satisfied if $G$ is a group--the operator system
$LUC(G)$ is a $C^*$-algebra.


title: Computing extinction maps of star nulling interferometers

abstract:
  Herein is discussed the performance of spaceborne nulling interferometers
searching for extra-solar planets, in terms of their extinction maps projected
on-sky. In particular, it is shown that the designs of Spatial Filtering (SF)
and Achromatic Phase Shifter (APS) subsystems, both required to achieve planet
detection and characterization, can sensibly affect the nulling maps produced
by a simple Bracewell interferometer. Analytical relationships involving cross
correlation products are provided and numerical simulations are performed,
demonstrating marked differences in the aspect of extinction maps and the
values of attained fringes contrasts. It is concluded that depending on their
basic principles and designs, FS and APS will result in variable capacities for
serendipitous discoveries of planets orbiting around their parent star. The
mathematical relationships presented in this paper are assumed to be general,
i.e. they should apply to other types of multi-apertures nulling
interferometers.


title:
Microscopic theory of the proximity effect in superconductor-graphene
  nanostructures

abstract:
  We present a theoretical analysis of the proximity effect at a
graphene-superconductor interface. We use a tight-binding model for the
electronic states in this system which allows to describe the interface at the
microscopic level. Two different interface models are proposed: one in which
the superconductor induces a finite pairing in the graphene regions underneath,
thus maintaining the honeycomb structure at the interface and one that assumes
that the graphene layer is directly coupled to a bulk superconducting
electrode. We show that properties like the Andreev reflection probability and
its channel decomposition depend critically on the model used to describe the
interface. We also study the proximity effect on the local density of states on
the graphene. For finite layers we analyze the induced minigap and how it is
reduced when the length of the layer increases. Results for the local density
of states profiles for finite and semi-infinite layers are presented.


title:
The treatment and rejection of two "strange" candidate events in the
  SLIM experiment

abstract:
  During the analysis of the CR39 Nuclear Track Detectors (NTDs) of the SLIM
experiment exposed at the high altitude lab of Chacaltaya (Bolivia) we observed
a sequence of puzzling etch-pits. We made a detailed investigation of all the
CR39 and Makrofol detectors in the same stack and in all the stacks around the
candidate event. We found a second puzzling sequence of etch-pits (plus some
single etch-pits). The analysis of this configuration was important because we
were searching for rare particles (Magnetic Monopoles, Nuclearites, Q-balls) in
the cosmic radiation. Thus we analyzed in detail the evolution with increasing
etching time of the etch-pits. We concluded that the two sequences of the
etch-pits (and some other background etch-pits) may have originated from a rare
manufacture malfunctioning which involved 1 m^2 of produced CR39.


title:
Probing the properties of convective cores through g modes: high-order g
  modes in SPB and gamma Doradus stars

abstract:
  In main sequence stars the periods of high-order gravity modes are sensitive
probes of stellar cores and, in particular, of the chemical composition
gradient that develops near the outer edge of the convective core. We present
an analytical approximation of high-order g modes that takes into account the
effect of the mu gradient near the core. We show that in main-sequence models,
similarly to the case of white dwarfs, the periods of high-order gravity modes
are accurately described by a uniform period spacing superposed to an
oscillatory component. The periodicity and amplitude of such component are
related, respectively, to the location and sharpness of the mu gradient.
  We investigate the properties of high-order gravity modes for stellar models
in a mass domain between 1 and 10 Msun, and the effects of the stellar mass,
evolutionary state, and extra-mixing processes on period spacing features. In
particular, we show that for models of a typical SPB star, a chemical mixing
that could likely be induced by the slow rotation observed in these stars, is
able to significantly change the g-mode spectra of the equilibrium model.
Prospects and challenges for the asteroseismology of gamma Doradus and SPB
stars are also discussed.


title: Dynamics of Kicked and Accelerated Massive Black Holes in Galaxies

abstract:
  A study is made of the behavior of massive black holes in disk galaxies that
have received an impulsive kick from a merger or a sustained acceleration from
an asymmetric jet. The motion of the gas, stars, dark matter, and massive black
hole are calculated using the GADGET-2 simulation code. The massive black hole
escapes the galaxy for kick velocities above about 600 km/s or accelerations
above about 4*10^{-8} cm/s^2 over time-scales of the order of 10^8 yr. For
smaller velocity kicks or smaller accelerations, the black hole oscillates
about the center of mass with a frequency which decreases as the kick velocity
or acceleration increases. The black hole displacements may give rise to
observable nonaxisymmetries in the morphology and dynamics of the stellar and
gaseous disk of the galaxy. In some cases the dynamical center of the galaxy is
seen to be displaced towards the direction of the BH acceleration with a
characteristic ``tongue--'' shaped extension of the velocity contours on the
side of the galaxy opposite the acceleration.


title: On the spread of epidemics in a closed heterogeneous population

abstract:
  Heterogeneity is an important property of any population experiencing a
disease. Here we apply general methods of the theory of heterogeneous
populations to the simplest mathematical models in epidemiology. In particular,
an SIR (susceptible-infective-removed) model is formulated and analyzed for
different sources of heterogeneity. It is shown that a heterogeneous model can
be reduced to a homogeneous model with a nonlinear transmission function, which
is given in explicit form. The widely used power transmission function is
deduced from a heterogeneous model with the initial gamma-distribution of the
disease parameters. Therefore, a mechanistic derivation of the phenomenological
model, which mimics reality very well, is provided. The equation for the final
size of an epidemic for an arbitrary initial distribution is found. The
implications of population heterogeneity are discussed, in particular, it is
pointed out that usual moment-closure methods can lead to erroneous conclusions
if applied for the study of the long-term behavior of the model.


title: On chirality of the vorticity of the Universe

abstract:
  We study chirality of the vorticity of the Universe within the
Einstein-Cartan cosmology. The role of the spin of fermion species during the
evolution of the Universe is studied by averaged spin densities and
Einstein-Cartan equations. It is shown that spin density of the light Majorana
neutrinos acts as a seed for vorticity at early stages of the evolution of the
Universe. Its chirality can be evaluated in the vicinity of the spacelike
infinity. It turns out that vorticity of the Universe has right-handed
chirality.


title:
Strain dependence of the Mn anisotropy in ferromagnetic semiconductors
  observed by x-ray magnetic circular dichroism

abstract:
  We demonstrate sensitivity of the Mn 3d valence states to strain in the
ferromagnetic semiconductors (Ga,Mn)As and (Al,Ga,Mn)As, using x-ray magnetic
circular dichroism (XMCD). The spectral shape of the Mn $L_{2,3}$ XMCD is
dependent on the orientation of the magnetization, and features with cubic and
uniaxial dependence are distinguished. Reversing the strain reverses the sign
of the uniaxial anisotropy of the Mn $L_3$ pre-peak which is ascribed to
transitions from the Mn 2p core level to p-d hybridized valence band hole
states. With increasing carrier localization, the $L_3$ pre-peak intensity
increases, indicating an increasing 3d character of the hybridized holes.


title: Cause of 1/f Noise: The Surge of Background Energy

abstract:
  Based on analyzing various physical examples for 1/f noise we found that the
1/f noise is caused by generating conditions as resonance in acoustics and the
effect of matter carrier is secondary. All the physical reasons are summarized
into The surge of background energy, then the 1/f noise is separated from
matter carrier. Therefore the attention is focus on the general characters of
1/f noise and the following viewpoints and results are of universal
significance. The work about cause for 1/f Noise came to a universal
relationship.
  All the question about 1/f noise were solved completely and systematical.
Follow-up study indicates that the crux of 1/f noise is a special phase whose
entropy is very small.


title:
Evidence for an Overluminosity of the Variable Star RR Lyr, and a
  Revised Distance to the LMC

abstract:
  We use theoretical models to establish a tight relationship for the absolute
magnitudes of RR Lyrae stars as a function of their periods and Stroemgren
pseudo-color c_0 = (u-v)_0 - (v-b)_0. Applying this to RR Lyr, and comparing
the result with the predicted average absolute magnitude for stars of similar
metallicity from the same models, yields an overluminosity of 0.064 +/- 0.013
mag in Stroemgren y (and thus similarly in V) for RR Lyr. Based on a revised
value for RR Lyr's trigonometric parallax, and on a newly derived reddening
value of E(B-V) = 0.015 +/- 0.020, we provide a corrected relationship between
average absolute magnitude and metallicity for RR Lyrae stars that takes RR
Lyr's evolutionary status fully into account for the first time. Applying this
relationship to the LMC, we derive a revised true distance modulus of (m-M)_0 =
18.44 +/- 0.11.


title:
Determination of the Parity of the Neutral Pion via the Four-Electron
  Decay

abstract:
  We present a new determination of the parity of the neutral pion via the
double Dalitz decay pi^0 -> e+ e- e+ e-. Our sample, which consists of 30511
candidate decays, was collected from K_L -> pi0 pi0 pi0 decays in flight at the
KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the
negative pi^0 parity, and place a limit on scalar contributions to the pi^0 ->
e+ e- e+ e- decay amplitude of less than 3.3% assuming CPT conservation. The
pi^0 gamma* gamma* form factor is well described by a momentum-dependent model
with a slope parameter fit to the final state phase space distribution.
Additionally, we have measured the branching ratio of this mode to be B(pi^0 ->
e+ e- e+ e-) = (3.26 +- 0.18) x 10^(-5).


title: BFKL Pomeron, Reggeized gluons and Bern-Dixon-Smirnov amplitudes

abstract:
  After a brief review of the BFKL approach to Regge processes in QCD and in
supersymmetric (SUSY) gauge theories we propose a strategy for calculating the
next-to-next-to-leading order corrections to the BFKL kernel. They can be
obtained in terms of various cross-sections for Reggeized gluon interactions.
The corresponding amplitudes can be calculated in the framework of the
effective action for high energy scattering. In the case of N=4 SUSY it is also
possible to use the Bern-Dixon-Smirnov (BDS) ansatz. For this purpose the
analytic properties of the BDS amplitudes at high energies are investigated, in
order to verify their self-consistency. It is found that, for the number of
external particles being larger than five, these amplitudes, beyond one loop,
are not in agreement with the BFKL approach which predicts the existence of
Regge cuts in some physical channels.


title: A look at Einsteins clocks synchronization

abstract:
  While Einstein clocks synchronization process is performed, one has a well
defined region in which the clocks are synchronized and another one in which
the clocks are not yet synchronized. The frontier between them evolves
differently from the perspective of observers in relative motion. A discussion
is conducted upon direct observation of the phenomenon and Minkowski diagrams.


title: Spin Dephasing and Hot Spins

abstract:
  At this summer school, I have tried to describe a general approach to quantum
transport problems based on the Non-equilibrium Green Function (NEGF) method .
I will not repeat this treatment here. Instead I will use this article to draw
attention to a core issue in quantum transport and how it is modeled within the
NEGF method. Specifically, I will discuss what constitutes a dephasing process
and how the standard descriptions may need to be extended to include what I
will call hot spin effects. These involve a number of subtle issues that tend
to get hidden in a purely formal description. So I have chosen instead to
illustrate the concepts using a concrete device, which is specially engineered
to enhance its sensitivity to spin dephasing and hot spin effects.


title: Vector Inflation

abstract:
  We propose a scenario where inflation is driven by non-minimally coupled
massive vector fields. In an isotropic homogeneous universe these fields behave
in presicely the same way as a massive minimally coupled scalar field.
Therefore our model is very similar to the model of chaotic inflation with
scalar field. For vector fields the isotropy of expansion is achived either by
considering a triplet of orthogonal vector fields or for the expense of $N$
randomly oriented vector fields. In the last case the substantial anisotropy of
the expansion of order $1/\sqrt{N}$ survives until the end of inflation. The
lightest vector fields might also force the late time acceleration of the
Universe.


title:
Influence of Functional Groups on Charge Transport in Molecular
  Junctions

abstract:
  Using density functional theory (DFT), we analyze the influence of five
classes of functional groups, as exemplified by NO2, OCH3, CH3, CCl3, and I, on
the transport properties of a 1,4-benzenedithiolate (BDT) and
1,4-benzenediamine (BDA) molecular junction with gold electrodes. Our analysis
demonstrates how ideas from functional group chemistry may be used to engineer
a molecule's transport properties, as was shown experimentally and using a
semiempirical model for BDA [Nano Lett. 7, 502 (2007)]. In particular, we show
that the qualitative change in conductance due to a given functional group can
be predicted from its known electronic effect (whether it is pi/sigma
donating/withdrawing). However, the influence of functional groups on a
molecule's conductance is very weak, as was also found in the BDA experiments.
The calculated DFT conductances for the BDA species are five times larger than
the experimental values, but good agreement is obtained after correcting for
self-interaction and image charge effects.


title:
Ages and metallicities of circumnuclear star formation regions from
  Gemini IFU observations

abstract:
  Aims: We derive the age and metallicity of circumnuclear star formation
regions (CNSFRs) located in the spiral galaxies NGC6951 and NGC1097, and
investigate the cause of the very low equivalent widths of emission lines found
for these regions.
  Methods: We used optical two-dimensional spectroscopic data obtained with
Gemini GMOS-IFUs and a grid of photoionization models to derive the the
metallicities and ages of CNSFRs.
  Results: We find star formation rates in the range 0.002-0.14 Msun/yr and
oxygen abundance of 12+log(O/H)~8.8 dex, similar to those of most metal-rich
nebulae located in the inner region of galactic disks.
  Conclusions: We conclude that the very low emission-line equivalent widths
observed in CNSFRs are caused by the ``contamination'' of the continuum by (1)
contribution of the underlying bulge continuum combined with (2) contribution
from previous episodes of star formation at the CNSFRs.


title:
Influence of Heavy Quark Recombination on the Nucleon Strangeness
  Asymmetry

abstract:
  The nucleon strange and anti-strange distribution asymmetry is an important
issue in the study of the nucleon structure. In this work, we show that the
heavy quark recombination processes from a perturbative QCD picture can give a
sizable influence on the measurement of the nucleon strangeness asymmetry from
charged-current charm production processes, such as the CCFR and NuTeV dimuon
measurements. When the influence of heavy quark recombination is considered, a
positive effective $\delta S^-_{\mathrm{HR}}$ should be added to the initially
extracted strangeness asymmetry $S^-\equiv\int dx[s(x)-\bar s(x)]x$, supporting
the strangeness asymmetry $S^-$ being positive, which is helpful to explain the
NuTeV anomaly within the framework of the standard model.


title: Asymptotic Iteration method for singular potentials

abstract:
  The asymptotic iteration method (AIM) is applied to obtain highly accurate
eigenvalues of the radial Schroedinger equation with the singular potential
V(r)=r^2+\lambda/r^\alpha (\alpha,\lambda> 0) in arbitrary dimensions. Certain
fundamental conditions for the application of AIM, such as a suitable
asymptotic form for the wave function, and the termination condition for the
iteration process, are discussed. Several suggestions are introduced to improve
the rate of convergence and to stabilize the computation. AIM offers a simple,
accurate, and efficient method for the treatment of singular potentials such as
V(r) valid for all ranges of coupling \lambda.


title: Spitzer-IRAC GLIMPSE of High Mass Protostellar Objects

abstract:
  The Spitzer-GLIMPSE point source catalog and images have been used to study a
sample of 381 massive protostellar candidates. IRAC-Point source photometry was
used to analyse colours, magnitudes and spectral indicies of the infrared
counterparts (IRCs) of massive protostellar objects and a bonafide sample of 50
point sources was obtained. Spectral energy distributions (SEDs) of these 50
sources was extended to the near-infrared and millimeter range by using 2MASS
and millimeter data from the literature. An online SED fitter tool based on
Monte-Carlo radiative transfer of an accretion model involving star,disk and
envelope was used to fit the SEDs of the 50 sources. The IRCs to massive
protostellar objects are found to successfully imitate the SEDs of evolutionary
phases similar to low mass star formation. Envelope accretion, rather than disk
accretion is found to be dominant in building the most massive stars.
Unresolved centimeter continuum emission is associated with 27 IRCs classified
as massive protostars suggesting that ionised accretion flows may play an
important role along with the molecular component. The morphology of the
infrared nebulae surrounding the IRCs have an unusual resemblance to the
morphologies of ultra-compact HII regions suggesting that these infrared
nebulae are possible precursors to the UCHII regions.


title: Nonvolatile ferroelectric control of ferromagnetism in (Ga,Mn)As

abstract:
  There is currently much interest in materials and structures that provide
coupled ferroelectric and ferromagnetic responses, with a long-term goal of
developing new memories and spintronic logic elements. Within the field there
is a focus on composites coupled by magnetostrictive and piezoelectric strain
transmitted across ferromagnetic-ferroelectric interfaces, but substrate
clamping limits the response in the supported multilayer configuration favoured
for devices. This constraint is avoided in a ferroelectric-ferromagnetic
bilayer in which the magnetic response is modulated by the electric field of
the poled ferroelectric. Here, we report the realization of such a device using
a diluted magnetic semiconductor (DMS) channel and a polymer ferroelectric
gate. Polarization reversal of the gate by a single voltage pulse results in a
persistent modulation of the Curie temperature as large as 5%. The device
demonstrates direct and quantitatively understood electric-fieldmediated
coupling in a multiferroic bilayer and may provide new routes to nanostructured
DMS materials and devices via ferroelectric domain nanopatterning. The
successful implementation of a polymer-ferroelectric gate fieldeffect
transistor (FeFET) with a DMS channel adds a new functionality to semiconductor
spintronics and may be of importance for future low-voltage spintronics devices
and memory structures.


title:
Combined effects of strong and electroweak FCNC effective operators in
  top quark physics at the LHC

abstract:
  We study the combined effects of both strong and electroweak dimension six
effective operators on flavour changing top quark physics at the LHC. Analytic
expressions for the cross sections and decay widths of several flavour changing
processes will be presented, as well as an analysis of the feasibility of their
observation at the LHC.


title: On strong ergodic properties of quantum dynamical systems

abstract:
  We show that the the shift on the reduced C*--algebras of RD--groups,
including the free group on infinitely many generators, and the amalgamated
free product C*--algebras, enjoys the very strong ergodic property of the
convergence to the equilibrium. Namely, the free shift converges, pointwise in
the weak topology, to the conditional expectation onto the fixed--point
subalgebra. Provided the invariant state is unique, we also show that such an
ergodic property cannot be fulfilled by any classical dynamical system, unless
it is conjugate to the trivial one--point dynamical system.


title: Hyperspherical Partial Wave Theory with Two-term Error Correction

abstract:
  Hyperspherical Partial Wave Theory has been applied to calculate T-matrix
elements and Single Differential Cross-Section (SDCS) results for
electron-hydrogen ionization process within Temkin-Poet model potential. We
considered three different values of step length to compute the radial part of
final state wave function. Numerical outcomes show that T-matrix elements and
SDCS values depend on the step length h. Here, we have presented T-matrix
elements and the corresponding SDCS results for 0.0075 a.u., 0.009 a.u. and
0.01 a.u. values of h and for 27.2eV, 40.8ev and 54.4eV impact energies. With
the help of the calculated data for three different step lengths, we have been
able to evaluate a two-term error function depending on the step length h.
Finally, two-term error corrected T-matrix elements and the corresponding SDCS
values have been computed. We fitted our two-term error corrected SDCS results
by a suitable curve and compared with the benchmark results of Jones et al.
[Phys. Rev. A, 66, 032717 (2002)]. Our fitted curves agree very well with the
calculated results of Jones et al. and two-term error corrected SDCS results
somewhere agree with the benchmark results. Two-term error corrected SDCS
results are significantly better than the calculated SDCS results of different
step lengths.


title: Moduli spaces of irreducible symplectic manifolds

abstract:
  We study the moduli spaces of polarised irreducible symplectic manifolds. By
a comparison with locally symmetric varieties of orthogonal type of dimension
20, we show that the moduli space of 2d polarised (split type) symplectic
manifolds which are deformation equivalent to degree 2 Hilbert schemes of a K3
surface is of general type if d is at least 12.


title: Zero dimensional arc valuations on smooth varieties

abstract:
  For a normalized transcendence degree zero arc valuation v on a nonsingular
variety X (with dim X > 1), we describe the maximal irreducible subset C(v) of
the arc space of X such that the valuation given by the order of vanishing
along a general arc of C(v) equals v. We describe C(v) both algebraically, in
terms of the sequence of valuation ideals of v, and geometrically, in terms of
the sequence of infinitely near points associated to v. When X is a surface,
our construction also applies to any divisorial valuation v, and in this case
C(v) coincides with a subset Ein, Lazarsfeld, and Mustata associate to v.


title:
Enhanced annealing, high Curie temperature and low-voltage gating in
  (Ga,Mn)As: A surface oxide control study

abstract:
  (Ga,Mn)As and related diluted magnetic semiconductors play a major role in
spintronics research because of their potential to combine ferromagnetism and
semiconducting properties in one physical system. Ferromagnetism requires
~1-10% of substitutional Mn_Ga. Unintentional defects formed during growth at
these high dopings significantly suppress the Curie temperature. We present
experiments in which by etching the (Ga,Mn)As surface oxide we achieve a
dramatic reduction of annealing times necessary to optimize the ferromagnetic
film after growth, and report Curie temperature of 180 K at approximately 8% of
Mn_Ga. Our study elucidates the mechanism controlling the removal of the most
detrimental, interstitial Mn defect. The limits and utility of electrical
gating of the highly-doped (Ga,Mn)As semiconductor are not yet established; so
far electric-field effects have been demonstrated on magnetization with tens of
Volts applied on a top-gate, field effect transistor structure. In the second
part of the paper we present a back-gate, n-GaAs/AlAs/GaMnAs transistor
operating at a few Volts. Inspired by the etching study of (Ga,Mn)As films we
apply the oxide-etching/re-oxidation procedure to reduce the thickness (arial
density of carriers) of the (Ga,Mn)As and observe a large enhancement of the
gating efficiency. We report gatable spintronic characteristics on a series of
anisotropic magnetoresistance measurements.


title:
Thermodynamics of Einstein-Born-Infeld black holes with negative
  cosmological constant

abstract:
  We study the thermodynamics associated to topological black hole solutions of
AdS gravity coupled to nonlinear electrodynamics (Born-Infeld) in any
dimension, using a background-independent regularization prescription for the
Euclidean action given by boundary terms which explicitly depend on the
extrinsic curvature (Kounterterms series). A finite action principle leads to
the correct definition of thermodynamic variables as Noether charges, which
satisfy a Smarr-like relation. In particular, for the odd-dimensional case, a
consistent thermodynamic description is achieved if the internal energy of the
system includes the vacuum energy for AdS spacetime.


title: Discovery of the progenitor of the type Ia supernova 2007on

abstract:
  Type Ia supernovae are exploding stars that are used to measure the
accelerated expansion of the Universe and are responsible for most of the iron
ever produced. Although there is general agreement that the exploding star is a
white dwarf in a binary system, the exact configuration and trigger of the
explosion is unclear, which could hamper their use for precision cosmology. Two
families of progenitor models have been proposed. In the first, a white dwarf
accretes material from a companion until it exceeds the Chandrasekhar mass,
collapses and explodes. Alternatively, two white dwarfs merge, again causing
catastrophic collapse and an explosion. It has hitherto been impossible to
determine if either model is correct. Here we report the discovery of an object
in pre-supernova archival X-ray images at the position of the recent type Ia
supernova (2007on) in the elliptical galaxy NGC 1404. Deep optical images (also
archival) show no sign of this object. From this we conclude that the X-ray
source is the progenitor of the supernova, which favours the accretion model
for this supernova, although the host galaxy is older (6-9 Gyr) than the age at
which the explosions are predicted in the accreting models.


title: Elastic theory of Normal-Superfluid Boundary in trapped Fermi Gases

abstract:
  By modeling the normal-superfluid boundary in a trapped polarized Fermi gas
as an elastic membrane, we calculate the atomic density profile. For small
trapping anisotropy, we find that the superfluid-normal boundary remains
approximately elliptical, and has an aspect ratio different from that of the
trap. For very prolate clouds the boundary becomes distorted into a
capsule-like shape. We present an analytic explanation of this shape.


title: Magnetically Aligned Velocity Anisotropy in the Taurus Molecular Cloud

abstract:
  Velocity anisotropy induced by MHD turbulence is investigated using
computational simulations and molecular line observations of the Taurus
molecular cloud. A new analysis method is presented to evaluate the degree and
angle of velocity anisotropy using spectroscopic imaging data of interstellar
clouds. The efficacy of this method is demonstrated on model observations
derived from three dimensional velocity and density fields from the set of
numerical MHD simulations that span a range of magnetic field strengths. The
analysis is applied to 12CO J=1-0 imaging of a sub-field within the Taurus
molecular cloud. Velocity anisotropy is identified that is aligned within 10
degrees of the mean local magnetic field direction derived from optical
polarization measurements. Estimated values of the field strength based on
velocity anisotropy are consistent with results from other methods. When
combined with new column density measurements for Taurus, our magnetic field
strength estimate indicates that the envelope of the cloud is magnetically
subcritical. These observations favor strong MHD turbulence within the low
density, sub-critical, molecular gas substrate of the Taurus cloud.


title: Ultraviolet Spectroscopy of HD 44179

abstract:
  We have re-analyzed the ultraviolet spectrum of HD 44179, the central star(s)
of the Red Rectangle nebula, providing improved estimates of the column
density, rotational, and vibrational temperatures of the 4th Positive A-X
system of CO in absorption. The flux shortward of 2200 A is a complex blend of
CO features with no discernible stellar photosphere, making the identification
of other molecular species difficult, and the direct derivation of the dust
extinction curve impossible. We confirm that the spin-forbidden CO (a-X)
Cameron bands are likely produced by either collisional excitation or a
chemical reaction, not photoexcitation, but with a higher internal vibrational
excitation than previously determined. We also detect the spin-forbidden CO
a'-X, d-X, and e-X absorption features. The hot CO (A-X) bands exhibit a
blue-shift of ~300 km/s, likely occurring close to the white dwarf star(s)
suspected as the original source of the ultraviolet flux in the system, and
forming the base of the outflow of material in the Red Rectangle. The OH
"comet-band" system near 3000 A is also analyzed, and estimates of its
rovibrational temperatures determined. The source of the molecules studied in
this system is still unknown, but may be a combination of gaseous material
associated with the star(s), or processed material from the surrounding dust
torus.


title: Nanoscale heat transfer at contact between a hot tip and a substrate

abstract:
  Hot tips are used either for characterizing nanostructures by using scanning
thermal microscopes or for local heating to assist data writing. The tip-sample
thermal interaction involves conduction at solid-solid contact as well as
conduction through the ambient gas and through the water meniscus. We analyze
those three heat transfer modes with experimental data and modeling. We
conclude that the three modes contribute in a similar manner to the thermal
contact conductance but they have distinct contact radii ranging from 30 nm to
1 micron. We also show that any scanning thermal microscope has a 1-3 microns
resolution when used in ambient air.


title: Why stratification may hurt, & how much

abstract:
  There are circumstances under which stratified sampling is worse than simple
random sampling, even if the allocation of the sample sizes is optimal. This
phenomenon was discovered more than sixty years ago, but is not as widely known
as one might expect. We provide it with lower and upper bounds for its badness
as well as with an explanation.


title: Toric surface codes and Minkowski length of polygons

abstract:
  In this paper we prove new lower bounds for the minimum distance of a toric
surface code defined by a convex lattice polygon P. The bounds involve a
geometric invariant L(P), called the full Minkowski length of P which can be
easily computed for any given P.


title:
The Globular Cluster M15. I. Identification, Discovery, and Period
  Determination of Variable Stars

abstract:
  We present new $BVI$ CCD photometry for variables in the globular cluster
M15. Our photometry was obtained using both the image subtraction package ISIS
and DAOPHOT/ALLFRAME. The data were acquired in 2001 on two observing runs on
11 observing nights using the 2-m telescope of the Bulgarian National
Astronomical Observatory ``Rozhen'' with a Photometrics CCD camera. For 40
previously known variables, we present a period for the first time, and
improved periods were obtained for many previously known variables. Fourteen
new variables are reported. We present updated Bailey diagrams for the cluster
and discuss its Oosterhoff classification. Although many of M15's RRab
pulsators fall at an intermediate locus between Oosterhoff types I and II in
the Bailey diagram, we argue that M15 is indeed a bona-fide Oosterhoff type II


title: Well-Posedness for the Euler-Nordstrom System with Cosmological Constant

abstract:
  In this paper the author considers the motion of a relativistic perfect fluid
with self-interaction mediated by Nordstrom's scalar theory of gravity. The
evolution of the fluid is determined by a quasilinear hyperbolic system of
PDEs, and a cosmological constant is introduced in order to ensure the
existence of non-zero constant solutions. Accordingly, the initial value
problem for a compact perturbation of an infinitely extended quiet fluid is
studied. Although the system is neither symmetric hyperbolic nor strictly
hyperbolic, Christodoulou's constructive results on the existence of energy
currents for equations derivable from a Lagrangian can be adapted to provide
energy currents that can be used in place of the standard energy principle
available for first-order symmetric hyperbolic systems. After providing such
energy currents, the author uses them to prove that the Euler-Nordstrom system
with a cosmological constant is well-posed in a suitable Sobolev space.


title:
Zero-crossing Shapiro steps in focused-ion-beam-tailored high-$T_c$
  superconducting microstructures

abstract:
  Microwave response of S-shaped Bi$_2$Sr$_2$CaCu2O$_{8+x}$ (Bi-2212)
micron-scale samples, in which the supercurrent was forced to flow
perpendicular to the crystal layers, was investigated. A treatment with a
focused ion beam allowed us to reduce the plasma frequency down to $f_p$$\sim$5
GHz at $T$=0.3 K in naturally stacked Josephson junctions in a crystal. We
observed Shapiro steps at frequencies as low as $\sim$5 GHz. Well-developed
zero-crossing Shapiro steps were observed at frequencies as low as $\sim$10
GHz. They appeared as constant-voltage plateaus with a non-zero voltage
occurring at zero bias current. We confirmed that zero-crossing Shapiro steps
in the Bi-2212 stacked junctions can be observed when the irradiated frequency
is sufficiently larger than $f_p$. The observed high-order fractional steps in
the microwave responses indicate that the interlayer-coupled Bi-2212 Josephson
junctions have nonsinusoidal current-phase relation. Based on the temperature
dependence of the steps we also showed that the finite slope of the steps is
due to the enhancement of the phase diffusion effect.


title: Concurrence of Stochastic 1-Qubit Maps

abstract:
  Explicit expressions for the concurrence of all positive and trace-preserving
("stochastic") 1-qubit maps are presented. By a new method we find the relevant
convex roof pattern. We conclude that two component optimal decompositions
always exist. Our results can be transferred to $2 \times n$-quantum systems
providing the concurrence for all rank two density operators as well as a lower
bound for their entanglement of formation.


title: Gross Theory Model for Neutrino-Nucleus Cross Section

abstract:
  The nuclear gross theory, originally formulated by Takahashi and Yamada for
the $\beta$-decays, is applied for the electronic-neutrino nucleus reactions,
employing a more realistic description to the energetics of the Gamow-Teller
resonances. The model parameters are gauged from the most recent experimental
data, both for $\beta^-$ decay and electron-capture, separately for even-even,
even-odd, odd-odd, odd-even nuclei. The numerical estimates for
neutrino-nucleus cross sections agree fairly well with previous evaluations
done within the framework of microscopic models. The formalism presented here
can be extended to the heavy nuclei mass region, where weak processes are quite
relevant, which is of astrophysical interest because of its applications in
supernova explosive nucleosynthesis.


title: The Bernstein-Gelfand-Gelfand complex and Kasparov theory for SL(3,C)

abstract:
  Let $G=\mathrm{SL}(3,\mathbb{C})$. We construct an element of $G$-equivariant
$K$-homology from the Bernstein-Gelfand-Gelfand complex for $G$. This furnishes
an explicit splitting of the restriction map from the Kasparov representation
ring $R(G)$ to the representation ring $R(K)$ of its maximal compact subgroup,
and the splitting factors through the equivariant $K$-homology of the flag
variety of $G$. In particular, we obtain a new model for the gamma element of
$G$.
  The proof makes extensive use of earlier results of the author concerning
harmonic analysis of longitudinal psuedodifferential operators on the flag
variety.


title: The Nascent Red Sequence at z~2

abstract:
  We present new constraints on the evolution of the early-type galaxy
color-magnitude relation (CMR) based on deep near-infrared imaging of a galaxy
protocluster at z=2.16 obtained using NICMOS on-board the Hubble Space
Telescope. This field contains a spectroscopically confirmed space-overdensity
of Lyman-alpha and H-alpha emitting galaxies which surrounds the powerful radio
galaxy MRC 1138-262. Using these NICMOS data we identify a significant
surface-overdensity (= 6.2x) of red J-H galaxies in the color-magnitude diagram
(when compared with deep NICMOS imaging from the HDF-N and UDF). The
optical-NIR colors of these prospective red-sequence galaxies indicate the
presence of on-going dust-obscured star-formation or recently formed (<~ 1.5
Gyr)stellar populations in a majority of the red galaxies. We measure the slope
and intrinsic scatter of the CMR for three different red galaxy samples
selected by a wide color cut, and using photometric redshifts both with and
without restrictions on rest-frame optical morphology. In all three cases both
the rest-frame $U-B$ slope and intrinsic color scatter are considerably higher
than corresponding values for lower redshift galaxy clusters. These results
suggest that while some relatively quiescent galaxies do exist in this
protocluster both the majority of the galaxy population and hence the
color-magnitude relation are still in the process of forming, as expected.


title: Maass relations in higher genus

abstract:
  For an arbitrary even genus $2n$ we show that the subspace of Siegel cusp
forms of degree $2n$ generated by Ikeda lifts of elliptic cusp forms can be
characterized by certain linear relations among Fourier coefficients. This
generatizes the work of Kohnen and Kojima.


title: On the detection of the progenitor of the type Ia supernova 2007on

abstract:
  We present new Chandra X-ray observations and detailed astrometry of the
field of the type Ia supernova 2007on, for which the detection of a likely
progenitor in archival Chandra data was recently reported.
  No source is detected in the new Chandra images, taken six weeks after
optical maximum. We calculate a 90-99% probability that any X-ray source near
the position of the supernova (SN) is fainter than in the pre-outburst images,
depending on the choice of aperture, which supports the identification of the
archival X-ray source with the SN.
  Detailed astrometry of the X-ray and new optical images, however, gives an
offset between the supernova and the measured X-ray source position of
1.15+/-0.27". Extensive simulations show that the probability of finding an
offset of this magnitude is ~1%, equal to the (trial-corrected) probability of
a chance alignment with any X-ray source in the field. This casts doubt on the
identification of the X-ray source with the progenitor, although the scenario
in which at least some of the observed X-rays are connected to the supernova
may be the least unlikely based on all available data.
  After a brief review of the auxiliary evidence, we conclude that only future
X-ray observations can shed further light on the proposed connection between
the X-ray source and the progenitor of SN 2007on, and thus whether an accreting
white dwarf scenario is truly favoured for this SN Ia.


title:
Indecomposable semiinfinite string-localized positive energy matter and
  "darkness"

abstract:
  In the absence of interactions indecomposable positive energy quantum matter
comes in form of three families of which the massless so called "infinite spin"
family which appeared first in Wigner's famous 1939 work is (if mentioned at
all) usually dismissed as "unphysical" but without indicating what principle
(if at all) is being violated. Using novel methods which are particularly
suited for problems of localization, it was shown that these representations
cannot be generated by pointlike localized fields but rather require the
introduction of string-like generators which are localized along semiinfinite
spacelike strings. We argue that such objects can neither be registered in
quasilocal Araki-Haag counters nor pair-produced from standard matter.
Reviewing the mathematical status of Murphy's law in local quantum physics
(everything which is not prohibited to couple does indeed couple) off and on
shell, we are led to the result that perfect darkness is only possible in QFT
with string-localized fields. PACS: 95.35+d, 11.10-z, 11.30Cp


title: On the Evolution of the Dense Core Mass Function

abstract:
  The mass distributions of dense cores in star-forming regions are measured to
have a shape similar to the initial mass function of stars. This has been
generally interpreted to mean that the constituent cores will form individual
stars or stellar systems at a nearly constant star formation efficiency. This
article presents a series of numerical experiments evolving distributions of
dense cores into stars to quantify the effects of stellar multiplicity, global
core fragmentation, and a varying star formation efficiency. We find that the
different evolutionary schemes have an overall small effect on the shape of the
resultant distribution of stars. Our results imply that at the current level of
observational accuracy the comparison between the mass functions of dense cores
and stars alone is insufficient to discern between different evolutionary
models. Observations over a wide range of mass scales including the high or
low-mass tails of these distributions have the largest potential for discerning
between different core evolutionary schemes.


title: ALFALFA: an Exploration of the z=0 HI Universe

abstract:
  The Arecibo Legacy Fast ALFA (ALFALFA) Survey is a program aimed at obtaining
a census of HI-bearing objects over a cosmologically significant volume of the
local Universe. It will cover 7074 square degrees of the high latitude sky
accessible with the Arecibo 305m telescope, using the 7-beam feed L-band feed
array (ALFA). Started in February 2005, as of Summer of 2007 survey
observations are 44\% complete. ALFALFA offers an improvement of about one
order of magnitude in sensitivity, 4 times the angular resolution, 3 times the
spectral resolution, and 1.6 times the total bandwidth of HIPASS. Although it
will cover only one quarter the sky solid angle surveyed by HIPASS, ALFALFA
will detect approximately six times as many sources, with a median depth of 110
Mpc. Preliminary results of ALFALFA are presented, with emphasis on those
related with the Virgo cluster.


title: Stability of Superflow for Ultracold Fermions in Optical Lattices

abstract:
  Motivated by recent observations of superfluidity of ultracold fermions in
optical lattices, we investigate the stability of superfluid flow of paired
fermions in the lowest band of a strong optical lattice. For fillings close to
one fermion per site, we show that superflow breaks down via a dynamical
instability leading to a transient density wave. At lower fillings, there is a
distinct dynamical instability, where the superfluid stiffness becomes
negative; this evolves, with increasing pairing interaction, from the fermion
pair breaking instability to the well-known dynamical instability of lattice
bosons. Our most interesting finding is the existence of a transition, over a
range of fillings close to one fermion per site, from the fermion depairing
instability to the density wave instability as the strength of the pairing
interaction is increased.


title: Evolution of the 21 cm signal throughout cosmic history

abstract:
  The potential use of the redshifted 21 cm line from neutral hydrogen for
probing the epoch of reionization is motivating the construction of several
low-frequency interferometers. There is also much interest in the possibility
of constraining the initial conditions from inflation and the nature of the
dark matter and dark energy by probing the power-spectrum of density
perturbations in three dimensions and on smaller scales than probed by the
microwave background anisotropies. Theoretical understanding of the 21 cm
signal has been fragmented into different regimes of physical interest. In this
paper, we make the first attempt to describe the full redshift evolution of the
21 cm signal between 0<z<300.
  We include contributions to the 21 cm signal from fluctuations in the gas
density, temperature and neutral fraction, as well as the Lyman alpha flux, and
allow for a post-reionization signal from damped Ly alpha systems. Our
comprehensive analysis provides a useful foundation for optimizing the design
of future arrays whose goal is to separate the particle physics from the
astrophysics, either by probing the peculiar velocity distortion of the 21 cm
power spectrum, or by extending the 21 cm horizon to z > 25 before the first
galaxies had formed, or to z < 6 when the residual pockets of hydrogen trace
large scale structure.


title: A new abundance scale for the globular cluster 47 Tuc

abstract:
  We present chemical abundances for O, Na, Mg, Al, Si, Ca, Ti and Fe in eight
red giants and one turnoff star in the metal rich globular cluster 47 Tuc,
based on spectroscopy with the MIKE high resolution spectrograph on the
Magellan 6.5-m Clay telescope. A robust line by line differential abundance
analysis technique, relative to the K-giant Arcturus, was used to reduce
systematic errors from atmospheric and atomic parameters. Our derived mean LTE
[Fe/H] of -0.76 +- 0.01 +- 0.04 dex (random and systematic error, respectively)
is more metal poor by about 0.1 dex than recent literature results. The
chemical element ratios in this nearby globular cluster most closely resemble
those of the Galactic bulge, although there is a non-negligible overlap with
the composition of thick-disk stars. We find that the [Al/Fe] and [Na/Fe]
ratios coincide with the upper boundary of the trends seen in the bulge and
thick disk. There is only a small intrinsic scatter in the majority of the
abundance ratios, indicating that 47 Tuc is mostly a rather chemically
homogeneous system.


title:
Complexity on Small Scales III: Iron and alpha Element Abundances in the
  Carina Dwarf Spheroidal Galaxy

abstract:
  We have obtained high-resolution spectroscopy of ten red giants in the Carina
dwarf spheroidal (dSph) with UVES at the ESO/VLT. Here we present the
abundances of O,Na,Mg,Si,Ca,Ti and Fe. By comparing the iron abundances [Fe/H]
with calcium triplet (CaT) metallicities we show that the empirical CaT
technique yields good agreement with the high-resolution data for [Fe/H]>-2
dex, but tends to deviate at lower metallicities. We identify two metal poor
stars with iron abundances of -2.72 and -2.50 dex. These stars are found to
have enhanced [alpha/Fe] ratios similar to those of stars in the Milky Way
halo. However, the bulk of the Carina red giants are depleted in the [alpha/Fe]
abundance ratios with respect to the Galactic halo at a given metallicity. One
of our targets, with a [Fe/H] of -1.5 dex, is considerably depleted in almost
all of the alpha-elements by ~0.5 dex compared to the solar values. Such a low
[alpha/Fe] can be produced by stochastical fluctuations in terms of an
incomplete mixing of single Type Ia and II SNe events into the ISM. Our derived
element ratios are consistent with the episodic and extended SF in Carina known
from its color-magnitude diagram. We find a considerable star-to-star scatter
in the abundance ratios. This suggests that Carina's SF history varies with
position within the galaxy, with incomplete mixing. Alternatively, the SF rate
is so low that the high-mass stellar IMF is sparsely populated, as
statistically expected in low-mass star clusters, leading to real scatter in
the resultant mass-integrated yields. Both ideas are consistent with slow
stochastic SF in dissolving associations, so that one may not speak of a single
SF history at a detailed level (Abridged).