title: Quantum interference from remotely trapped ions

abstract:
  We observe quantum interference of photons emitted by two continuously
laser-excited single ions, independently trapped in distinct vacuum vessels.
High contrast two-photon interference is observed in two experiments with
different ion species, calcium and barium. Our experimental findings are
quantitatively reproduced by Bloch equation calculations. In particular, we
show that the coherence of the individual resonance fluorescence light field is
determined from the observed interference.


title: Unified approach to nuclear densities from exotic atoms

abstract:
  Parameters of nuclear density distributions are derived from least-squares
fits to strong interaction observables in exotic atoms. Global analyses of
antiprotonic and pionic atoms show reasonably good agreement between the two
types of probes regarding the average behaviour of root-mean-square radii of
the neutron distributions. Apparent conflict regarding the shape of the neutron
distribution is attributed to different radial sensitivities of these two
probes.


title:
Linearly polarised photon beams at ELSA and measurement of the beam
  asymmetry in pi^0-photoproduction off the proton

abstract:
  At the electron accelerator ELSA a linearly polarised tagged photon beam is
produced by coherent bremsstrahlung off a diamond crystal. Orientation and
energy range of the linear polarisation can be deliberately chosen by accurate
positioning of the crystal with a goniometer. The degree of polarisation is
determined by the form of the scattered electron spectrum. Good agreement
between experiment and expectations on basis of the experimental conditions is
obtained. Polarisation degrees of P = 40% are typically achieved at half of the
primary electron energy. The determination of P is confirmed by measuring the
beam asymmetry, \Sigma, in pi^0 photoproduction and a comparison of the results
to independent measurements using laser backscattering.


title: Anomalous Magnetic Properties in Ni50Mn35In15

abstract:
  We present here a comprehensive investigation of the magnetic ordering in
Ni50Mn35In15 composition. A concomitant first order martensitic transition and
the magnetic ordering occurring in this off-stoichiometric Heusler compound at
room temperature signifies the multifunctional character of this magnetic shape
memory alloy. Unusual features are observed in the dependence of the
magnetization on temperature that can be ascribed to a frustrated magnetic
order. It is compelling to ascribe these features to the cluster type
description that may arise due to inhomogeneity in the distribution of magnetic
atoms. However, evidences are presented from our ac susceptibility, electrical
resistivity and dc magnetization studies that there exists a competing
ferromagnetic and antiferromagnetic order within crystal structure of this
system. We show that excess Mn atoms that substitute the In atoms have a
crucial bearing on the magnetic order of this compound. These excess Mn atoms
are antiferromagnetically aligned to the other Mn, which explains the peculiar
dependence of magnetization on temperature.


title:
1.25 Approximation Algorithm for the Steiner Tree Problem with Distances
  One and Two

abstract:
  We give a 1.25 approximation algorithm for the Steiner Tree Problem with
distances one and two, improving on the best known bound for that problem.


title:
Rotation on sub-kpc scales in the strongly lensed z~3 'arc&core' and
  implications for high-redshift galaxy dynamics

abstract:
  Strongly lensed galaxies at high redshift provide a unique window into the
early universe. We compare the internal kinematics of the strongly lensed
Lyman-break galaxy (LBG) 'arc&core' at z=3.2 (the first strongly lensed z~3 LBG
with the signs of rotation on sub-kiloparsec scales) with an LBG that is not
gravitationally lensed, as well as with a larger sample of actively
star-forming galaxies at slightly lower redshifts. All galaxies have deep
rest-frame optical integral-field spectroscopy obtained with the VLT. The
unlensed galaxies appear to have a larger ratio of random to bulk motion. Field
galaxies also have broader lines than strongly lensed LBGs with rest-optical
spectroscopy, where spectra were extracted from regions with similar physical
size. To ensure observational success, studies of high-redshift galaxy
kinematics often focus on bright and luminous targets, and our comparison
suggests that this may lead to a serious bias.


title:
Invariant distributions on non-distinguished nilpotent orbits with
  application to the Gelfand property of (GL(2n,R),Sp(2n,R))

abstract:
  We study invariant distributions on the tangent space to a symmetric space.
We prove that an invariant distribution with the property that both its support
and the support of its Fourier transform are contained in the set of
non-distinguished nilpotent orbits, must vanish. We deduce, using recent
developments in the theory of invariant distributions on symmetric spaces that
the symmetric pair (GL(2n,R),Sp(2n,R)) is a Gelfand pair. More precisely, we
show that for any irreducible smooth admissible Frechet representation
$(\pi,E)$ of GL(2n,R) the space of continuous functionals
$Hom_{Sp_{2n}(R)}(E,C)$ is at most one dimensional. Such a result was
previously proven for p-adic fields in [HR] for the field of complex numbers in
[S].


title: Generalization Of The Gross-Perry Metrics

abstract:
  A class of SO(n+1) symmetric solutions of the (N+n+1)-dimensional Einstein
equations is found. It contains 5-dimensional metrics of Gross and Perry and
Millward.


title: A note on the dynamical zeta function of general toral endomorphisms

abstract:
  It is well-known that the Artin-Mazur dynamical zeta function of a hyperbolic
or quasi-hyperbolic toral automorphism is a rational function, which can be
calculated in terms of the eigenvalues of the corresponding integer matrix. We
give an elementary proof of this fact that extends to the case of general toral
endomorphisms without change. The result is a closed formula that can be
calculated by integer arithmetic only. We also address the functional equation
and the relation between the Artin-Mazur and Lefschetz zeta functions.


title:
Variation in p-mode power over solar cycle 23 as seen from BiSON and
  GOLF observations

abstract:
  We analyzed BiSON and GOLF/SoHO data with a new technique, to investigate
p-mode power variation over solar cycle 23. We found a decrease in the mean
velocity power of about 20% for BiSON during the ascending phase, in agreement
with previous findings. We also found that GOLF, during the red-wing
configuration, seems to be working at a different height than the theoretically
computed one.


title:
Weak disorder strongly improves the selective enhancement of diffusion
  in a tilted periodic potential

abstract:
  The diffusion of an overdamped Brownian particle in a tilted periodic
potential is known to exhibit a pronounced enhancement over the free thermal
diffusion within a small interval of tilt-values. Here we show that weak
disorder in the form of small, time-independent deviations from a strictly
spatially periodic potential may further boost this diffusion peak by orders of
magnitude. Our general theoretical predictions are in excellent agreement with
experimental observations.


title: SOSEMANUK: a fast software-oriented stream cipher

abstract:
  Sosemanuk is a new synchronous software-oriented stream cipher, corresponding
to Profile 1 of the ECRYPT call for stream cipher primitives. Its key length is
variable between 128 and 256 bits. It ac- commodates a 128-bit initial value.
Any key length is claimed to achieve 128-bit security. The Sosemanuk cipher
uses both some basic design principles from the stream cipher SNOW 2.0 and some
transformations derived from the block cipher SERPENT. Sosemanuk aims at
improv- ing SNOW 2.0 both from the security and from the efficiency points of
view. Most notably, it uses a faster IV-setup procedure. It also requires a
reduced amount of static data, yielding better performance on several
architectures.


title:
Global dynamics of high area-to-mass ratios GEO space debris by means of
  the MEGNO indicator

abstract:
  In this paper we provide an extensive analysis of the global dynamics of
high-area-to-mass ratios geosynchronous (GEO) space debris, applying a recent
technique developed by Cincotta et al. (2000), Mean Exponential Growth factor
of Nearby Orbits (MEGNO), which provides an efficient tool to investigate both
regular and chaotic components of the phase space. We compute a stability
atlas, for a large set of near-geosynchronous space debris by numerically
computing the MEGNO indicator, to provide an accurate understanding of the
location of stable and unstable orbits as well as the timescale of their
exponential divergence in case of chaotic motion. The results improve the
analysis presented in Breiter et al. (2005a) notably by considering the
particular case of high-area-to-mass ratios space debris. The results indicate
that chaotic orbits region can be highly relevant, especially for very high
area-to-mass ratios. Then, we provide some numerical investigations and an
analytical theory which lead to a detailed understanding of the resonance
structures appearing in the phase space. These analyses bring to the fore a
relevant class of secondary resonances on both sides of the well-known
pendulum-like pattern of geostationary space debris, leading to complex
dynamics of such objects.


title:
Neutrino Detection with the Surface Array of the Pierre Auger
  Observatory

abstract:
  The Pierre Auger Observatory has the capability of detecting neutrino-induced
extensive air showers by searching for very inclined showers with a significant
electromagnetic component. In order to study the detector response of the
surface array of the Pierre Auger Observatory, Monte Carlo simulations of
up-going and down-going neutrino showers for all flavors were performed. A set
of relevant observables were determined to discriminate these showers from the
background of very inclined hadronic showers and the identification efficiency
was studied. The acceptance and the expected event rates, based on the
assumption of the incoming neutrino flux, were finally calculated.


title:
Chemical modeling of L183 (= L134N) : an estimate of the ortho/para H2
  ratio

abstract:
  Context. The high degree of deuteration observed in some prestellar cores
depends on the ortho-to-para H2 ratio through the H3+ fractionation. Aims. We
want to constrain the ortho/para H2 ratio across the L183 prestellar core. This
is mandatory to correctly describe the deuter- ation amplification phenomenon
in depleted cores such as L183 and to relate the total (ortho+para) H2D+
abundance to the sole ortho-H2D+ column density measurement. Methods. To
constrain this ortho/para H2 ratio and derive its profile, we make use of the
N2D+ /N2H+ ratio and of the ortho-H2D+ observations performed across the
prestellar core. We use two simple chemical models limited to an almost totally
depleted core description. New dissociative recombination and trihydrogen
cation-dihydrogen reaction rates (including all isotopologues) are presented in
this paper and included in our models. Results. We estimate the H2D+ ortho/para
ratio in the L183 cloud, and constrain the H2 ortho/para ratio : we show that
it is varying across the prestellar core by at least an order of magnitude
being still very high (~0.1) in most of the cloud. Our time-dependent model
indicates that the prestellar core is presumably older than 1.5-2 x 10^5 years
but that it may not be much older. We also show that it has reached its present
density only recently and that its contraction from a uniform density cloud can
be constrained. Conclusions. A proper understanding of deuteration chemistry
cannot be attained without taking into account the whole ortho/para family of
molecular hydrogen and trihydrogen cation isotopologues as their relations are
of utmost importance in the global scheme. Tracing the ortho/para H2 ratio
should also give useful constraints on the dynamical evolution of prestellar
cores.


title: A new extended q-deformed KP hierarchy

abstract:
  A method is proposed in this paper to construct a new extended q-deformed KP
($q$-KP) hiearchy and its Lax representation. This new extended $q$-KP
hierarchy contains two types of q-deformed KP equation with self-consistent
sources, and its two kinds of reductions give the q-deformed Gelfand-Dickey
hierarchy with self-consistent sources and the constrained q-deformed KP
hierarchy, which include two types of q-deformed KdV equation with sources and
two types of q-deformed Boussinesq equation with sources. All of these results
reduce to the classical ones when $q$ goes to 1. This provides a general way to
construct (2+1)- and (1+1)-dimensional q-deformed soliton equations with
sources and their Lax representations.


title:
Tuning the conductance of molecular junctions: transparent versus
  tunneling regimes

abstract:
  We present a theoretical study of the transport characteristics of molecular
junctions, where first-row diatomic molecules are attached to (001) gold and
platinum electrodes. We find that the conductance of all of these junctions is
of the order of the conductance quantum unit $G_0$, spelling out that they
belong to the transparent regime. We further find that the transmission
coefficients show wide plateaus as a function of the energy, instead of the
usual sharp resonances that signal the molecular levels in the tunneling
regime. We use Caroli's model to show that this is a rather generic property of
the transparent regime of a junction, which is driven by a strong effective
coupling between the delocalized molecular levels and the conduction channels
at the electrodes. We analyse the transmission coefficients and chemical
bonding of gold/Benzene and gold/Benzene-dithiolate (BDT) junctions to
understand why the later show large resistances, while the former are highly
conductive.


title:
Evolution of initially localized perturbations in stratified ionized
  disks

abstract:
  A detailed solution of an initial value problem of a vertically localized
initial perturbation in rotating magnetized vertically stratified disk is
presented. The appropriate linearized MHD equations are solved by employing the
WKB approximation and the results are verified numerically. The
eigenfrequencies as well as eigenfunctions are explicitly obtained. It is
demonstrated that the initial perturbation remains confined within the disk. It
is further shown that thin enough disks are stable but as their thickness grows
increasing number of unstable modes participate in the solution of the initial
value problem. However it is demonstrated that due to the localization of the
initial perturbation the growth time of the instability is significantly longer
than the calculated inverse growth rate of the individual unstable
eigenfunctions.


title: On holomorphic maps and Generalized Complex Geometry

abstract:
  We introduce a natural notion of holomorphic map between generalized complex
manifolds and we prove some related results on Dirac structures and generalized
Kaehler manifolds.


title:
Critical Casimir forces in colloidal suspensions on chemically patterned
  surfaces

abstract:
  We investigate the behavior of colloidal particles immersed in a binary
liquid mixture of water and 2,6-lutidine in the presence of a chemically
patterned substrate. Close to the critical point of the mixture, the particles
are subjected to critical Casimir interactions with force components normal and
parallel to the surface. Because the strength and sign of these interactions
can be tuned by variations in the surface properties and the mixtures
temperature, critical Casimir forces allow the formation of highly ordered
monolayers but also extend the use of colloids as model systems.


title:
Star Formation at Very Low Metallicity. V. The Greater Importance of
  Initial Conditions Compared to Metallicity Thresholds

abstract:
  The formation of the first stars out of metal-free gas appears to result in
stars at least an order of magnitude more massive than in the present-day case.
We here consider what controls the transition from a primordial to a modern
initial mass function. It has been proposed that this occurs when effective
metal line cooling occurs at a metallicity threshold of Z/Z_sun > 10^{-3.5}. We
study the influence of low levels of metal enrichment on the cooling and
collapse of initially ionized gas in small protogalactic halos using
three-dimensional, smoothed particle hydrodynamics simulations with particle
splitting. Our initial conditions represent protogalaxies forming within a
previously ionized H ii region that has not yet had time to cool and recombine.
These differ considerably from those used in simulations predicting a
metallicity threshold, where the gas was initially cold and only partially
ionized. In the centrally condensed potential that we study here, a wide
variety of initial conditions for the gas yield a monolithic central collapse.
Our models show no fragmentation during collapse to number densities as high as
10^5 cm^{-3}, for metallicities reaching as high as 10^{-1} Z_sun in one
rotating case, far above the threshold suggested by previous work. Rotation
allows for the formation of gravitationally stable gas disks over large
fractions of the local Hubble time. Turbulence slows the growth of the central
density slightly, but both spherically symmetric and turbulent initial
conditions collapse and form a single sink particle. We therefore argue that
fragmentation at moderate density depends on the initial conditions for star
formation more than on the metal abundances present.


title:
Hysteresis in the electronic transport of V2O3 thin films:
  non-exponential kinetics and range scale of phase coexistence

abstract:
  The thermal hysteresis of the electronic transport properties were studied
for V2O3 thin films. The temporal evolution of the resistance shows the
out-of-equilibrium nature of this hysteresis with a very slow relaxation.
Partial cycles reveal not only a behavior consistent with phase coexistence,
but also the presence of spinodal temperatures which are largely separated. The
temperature spreading of phase coexistence is consistent with the bulk phase
diagram in the pressure-temperature plane, confirming that the film is
effectively under an effective pressure induced by the substrate.


title: Charge density of the electron at higher velocity

abstract:
  Depending on the recent experiments and some new way of explaining electron
we have developed here equations for velocities of different mode with the
charge density. This includes as well how the charge-density can be distributed
in the equatorial region with different velocities and observer-angles.


title:
Cosmological Constraints from calibrated Yonetoku and Amati relation
  implies Fundamental plane of Gamma-ray bursts

abstract:
  We consider two empirical relations using data only from the prompt emission
of Gamma-Ray Bursts (GRBs), peak energy ($E_p$) - peak luminosity ($L_p$)
relation (so called Yonetoku relation) and $E_p$-isotropic energy ($E_{\rm
iso}$) relation (so called Amati relation). We first suggest the independence
of the two relations although they have been considered similar and dependent.
  From this viewpoint, we compare constraints on cosmological parameters,
$\Omega_m$ and $\Omega_{\Lambda}$, from the Yonetoku and Amati relations
calibrated by low-redshift GRBs with $z < 1.8$. We found that they are
different in 1-$\sigma$ level, although they are still consistent in 2-$\sigma$
level. This and the fact that both Amati and Yonetoku relations have systematic
errors larger than statistical errors suggest the existence of a hidden
parameter of GRBs. We introduce the luminosity time $T_L$ defined by $T_L\equiv
E_{\rm iso}/L_p$ as a hidden parameter to obtain a generalized Yonetoku
relation as $(L_p/{10^{52} \rm{erg s^{-1}}}) =
  10^{-3.88\pm0.09}(E_p/{\rm{keV}})^{1.84\pm0.04}
  (T_L/{\rm{s}})^{-0.34\pm0.04}$. The new relation has much smaller systematic
error, 30%, and can be regarded as "Fundamental plane" of GRBs. We show a
possible radiation model for this new relation. Finally we apply the new
relation for high-redshift GRBs with $1.8 < z < 5.6$ to obtain
$(\Omega_m,\Omega_{\Lambda}) =
  (0.16^{+0.04}_{-0.06},1.20^{+0.03}_{-0.09})$, which is consistent with the
concordance cosmological model within 2-$\sigma$ level.


abstract:
  The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) is the
first interferometer dedicated to studying the cosmic microwave background
(CMB) radiation at 3mm wavelength. The choice of 3mm was made to minimize the
contributions from foreground synchrotron radiation and Galactic dust emission.
The initial configuration of seven 0.6m telescopes mounted on a 6-m hexapod
platform was dedicated in October 2006 on Mauna Loa, Hawaii. Scientific
operations began with the detection of a number of clusters of galaxies via the
thermal Sunyaev-Zel'dovich effect. We compare our data with Subaru weak lensing
data in order to study the structure of dark matter. We also compare our data
with X-ray data in order to derive the Hubble constant.


title: Electromagnetism and photons in continuous media

abstract:
  Different theoretical and experimental aspects of electromagnetic phenomena
in media is reviewed. The 100 year old Minkowski theory is in agreement with
most experiments, but has theoretical problems related to its implied validity
in all inertial frames. It is suggested that the similar Abraham theory should
be permanently laid to rest since it is not compatible with basic quantum
mechanics and is in disagreement with most experiments. Recently an effective
field theory has been proposed which avoids these problems by considering the
photon as a quasiparticle like any other excitation in condensed matter physics
for which the rest frame of the medium is a preferred frame. It relates many
different classical and quantum optical phenomena in a unified description.


title:
The molecular signature of highly conductive metal-molecule-metal
  junctions

abstract:
  The simplicity of single-molecule junctions based on direct bonding of a
small molecule between two metallic electrodes make them an ideal system for
the study of fundamental questions related to molecular electronics. Here we
study the conductance properties of six different molecules suspended between
Pt electrodes. All the molecular junctions show a typical conductance of about
1G0 which is ascribed to the dominant role of the Pt contacts. However, despite
the metallic-like conductivity, the individual molecular signature is
well-expressed by the effect of molecular vibrations in the inelastic
contribution to the conductance.


title: Solar axion search with the CAST experiment

abstract:
  The CAST (CERN Axion Solar Telescope) experiment is searching for solar
axions by their conversion into photons inside the magnet pipe of an LHC
dipole. The analysis of the data recorded during the first phase of the
experiment with vacuum in the magnet pipes has resulted in the most restrictive
experimental limit on the coupling constant of axions to photons. In the second
phase, CAST is operating with a buffer gas inside the magnet pipes in order to
extent the sensitivity of the experiment to higher axion masses. We will
present the first results on the $^{4}{\rm He}$ data taking as well as the
system upgrades that have been operated in the last year in order to adapt the
experiment for the $^{3}{\rm He}$ data taking. Expected sensitivities on the
coupling constant of axions to photons will be given for the recent $^{3}{\rm
He}$ run just started in March 2008.


title:
Neutralino Dark Matter in an SO(10) Model with Two-step Intermediate
  Scale Symmetry Breaking

abstract:
  We consider a supersymmetric Grand Unified Theory (GUT) based on the gauge
group SO(10) suggested by Aulakh et al., which features two--step intermediate
symmetry breaking, $SO(10) \to SU(4)_C \times SU(2)_L \times SU(2)_R \to
SU(3)_C \times U(1)_{B-L} \times SU(2)_L \times SU(2)_R \to SU(3)_C \times
SU(2)_L \times U(1)_Y$. {\bf $45, 54, 126+\overline{126}$} dimensional
representations of Higgs superfields are employed to achieve this symmetry
breaking chain. We also introduce a second, very heavy, pair of Higgs doublets,
which modifies the Yukawa couplings of matter fields relative to minimal SO(10)
predictions. We analyze the differences in the low energy phenomenology
compared to that of mSUGRA, assuming universal soft breaking scalar masses,
gaugino masses and trilinear couplings at the GUT scale. We find that thermal
neutralino Dark Matter remains viable in this scenario, although for small and
moderate values of $\tan\beta$ the allowed region is even more highly
constrained than in mSUGRA, and depends strongly on the the light neutrino
masses.


title: The AdS/CFT Correspondence and Light-Front QCD

abstract:
  We identify an invariant light-front coordinate $\zeta$ which allows the
separation of the dynamics of quark and gluon binding from the kinematics of
constituent spin and internal orbital angular momentum. The result is a
single-variable light-front Schrodinger equation for QCD which determines the
eigenspectrum and the light-front wavefunctions of hadrons for general spin and
orbital angular momentum. This frame-independent light-front wave equation is
equivalent to the equations of motion which describe the propagation of
spin-$J$ modes on anti-de Sitter (AdS) space. Light-front holography is a
remarkable feature of AdS/CFT: it allows hadronic amplitudes in the AdS fifth
dimension to be mapped to frame-independent light-front wavefunctions of
hadrons in physical space-time, thus providing a relativistic description of
hadrons at the amplitude level. In principle, the model can be systematically
improved by diagonalizing the full QCD light-front Hamiltonian on the AdS/QCD
basis. Quark and gluon hadronization can be computed at the amplitude level by
convoluting the off-shell $T$ matrix calculated from the QCD light-front
Hamiltonian with the hadronic light-front wavefunctions. We also note the
distinction between static observables such as the probability distributions
computed from the square of the light-front wavefunctions versus dynamical
observables such as the structure functions and the leading-twist single-spin
asymmetries measured in deep inelastic scattering which include the effects of
initial and final-state interactions.


title: Automorphic lifts of prescribed types

abstract:
  We prove a variety of results on the existence of automorphic Galois
representations lifting a residual automorphic Galois representation. We prove
a result on the structure of deformation rings of local Galois representations,
and deduce from this and the method of Khare and Wintenberger a result on the
existence of modular lifts of specified type for Galois representations
corresponding to Hilbert modular forms of parallel weight 2. We discuss some
conjectures on the weights of $n$-dimensional mod $p$ Galois representations.
Finally, we use recent work of Taylor to prove level raising and lowering
results for $n$-dimensional automorphic Galois representations.


title: The INTEGRAL long monitoring of persistent Ultra Compact X-ray Bursters

abstract:
  The combination of compact objects, short period variability and peculiar
chemical composition of the Ultra Compact X-ray Binaries make up a very
interesting laboratory to study accretion processes and thermonuclear burning
on the neutron star surface. The improved large optical telescopes and more
sensitive X-ray satellites have increased the number of known Ultra Compact
X-ray Binaries allowing their study with unprecedented detail. We analyze the
average properties common to all ultra compact Bursters observed by INTEGRAL
from ~0.2keV to ~150keV. We have performed a systematic analysis of the
INTEGRAL public data and Key-Program proprietary observations of a sample of
the Ultra Compact X-ray Binaries. In order to study their average properties in
a very broad energy band, we combined INTEGRAL with BeppoSAX and SWIFT data
whenever possible. For sources not showing any significant flux variations
along the INTEGRAL monitoring, we build the average spectrum by combining all
available data; in the case of variable fluxes, we use simultaneous INTEGRAL
and SWIFT observations when available. Otherwise we compared IBIS and PDS data
to check the variability and combine BeppoSAX with INTEGRAL/IBIS data. All
spectra are well represented by a two component model consisting of a
disk-blackbody and Comptonised emission. The majority of these compact sources
spend most of the time in a canonical low/hard state, with dominating
Comptonised component and accretion rate lower than ~10^{-9}Msolar/yr, not
depending on the used model to fit the data.


title:
Characterization of some causality conditions through the continuity of
  the Lorentzian distance

abstract:
  A classical result in Lorentzian geometry states that a strongly causal
spacetime is globally hyperbolic if and only if the Lorentzian distance is
finite valued for every metric choice in the conformal class. It is proven here
that a non-total imprisoning spacetime is globally hyperbolic if and only if
for every metric choice in the conformal class the Lorentzian distance is
continuous. Moreover, it is proven that a non-total imprisoning spacetime is
causally simple if and only if for every metric choice in the conformal class
the Lorentzian distance is continuous wherever it vanishes. Finally, a strongly
causal spacetime is causally continuous if and only if there is at least one
metric in the conformal class such that the Lorentzian distance is continuous
wherever it vanishes.


title:
Nonlinear diffusive-dispersive limits for multidimensional conservation
  laws

abstract:
  We consider a class of multidimensional conservation laws with vanishing
nonlinear diffusion and dispersion terms. Under a condition on the relative
size of the diffusion and dispersion coefficients, we establish that the
diffusive-dispersive solutions are uniformly bounded in a space Lp ($p$
arbitrary large, depending on the nonlinearity of the diffusion) and converge
to the classical, entropy solution of the corresponding multidimensional,
hyperbolic conservation law. Previous results were restricted to
one-dimensional equations and specific spaces Lp. Our proof is based on
DiPerna's uniqueness theorem in the class of entropy measure-valued solutions.


title: Statistical mechanical description of liquid systems in electric field

abstract:
  We formulate the statistical mechanical description of liquid systems for
both polarizable and polar systems in an electric field in the
$\mathbf{E}$-ensemble, which is the pendant to the thermodynamic description in
terms of the free energy at constant potential. The contribution of the
electric field to the configurational integral $\tilde{Q}_{N}(\mathbf{E})$ in
the $\mathbf{E}$-ensemble is given in an exact form as a factor in the
integrand of $\tilde{Q}_{N}(\mathbf{E})$. We calculate the contribution of the
electric field to the Ornstein-Zernike formula for the scattering function in
the $\mathbf{E}$-ensemble. As an application we determine the field induced
shift of the critical temperature for polarizable and polar liquids, and show
that the shift is upward for polarizable liquids and downward for polar
liquids.


title: Log-periodic modulation in one-dimensional random walks

abstract:
  We have studied the diffusion of a single particle on a one-dimensional
lattice. It is shown that, for a self-similar distribution of hopping rates,
the time dependence of the mean-square displacement follows an anomalous power
law modulated by logarithmic periodic oscillations. The origin of this
modulation is traced to the dependence on the length of the diffusion
coefficient. Both the random walk exponent and the period of the modulation are
analytically calculated and confirmed by Monte Carlo simulations.


title:
Real-Time Nearfield Acoustic Holography: Implementation of the Direct
  and Inverse Impulse Responses in the Time-Wavenumber Domain

abstract:
  The aim of the study is to demonstrate that some methods are more relevant
for implementing the Real-Time Nearfield Acoustic Holography than others. First
by focusing on the forward propagation problem, different approaches are
compared to build the impulse response to be used. One of them in particular is
computed by an inverse Fourier transform applied to the theoretical transfer
function for propagation in the frequency-wavenumber domain. Others are
obtained by directly sampling an analytical impulse response in the
time-wavenumber domain or by additional low-pass filtering. To estimate the
performance of each impulse response, a simulation test involving several
monopoles excited by non stationary signals is presented and some features are
proposed to assess the accuracy of the temporal signals resulting from
reconstruction processing on a forward plane. Then several inverse impulse
responses used to solve the inverse problem, which consists in back propagating
the acoustic signals acquired by the microphone array, are built directly from
a transfer function or by using Wiener inverse filtering from the direct
impulse responses obtained for the direct problem. Another simulation test is
performed to compare the signals reconstructed on the source plane. The same
indicators as for the propagation study are used to highlight the differences
between the methods tested for solving the Holography inverse problem.


title: Extremal Bases, Geometrically Separated Domains and Applications

abstract:
  We introduce the notion of extremal basis of tangent vector fields at a
boundary point of finite type of a pseudo-convex domain in $\mathbb{C}^n$. Then
we define the class of geometrically separated domains at a boundary point, and
give a description of their complex geometry. Examples of such domains are
given, for instance, by locally lineally convex domains, domains with locally
diagonalizable Levi form, and domains for which the Levi form have comparable
eigenvalues at a point. Moreover we show that these domains are localizable.
Then we define the notion of "adapted pluri-subharmonic function" to these
domains, and we give sufficient conditions for his existence. Then we show that
all the sharp estimates for the Bergman ans Szeg\"o projections are valid in
this case. Finally we apply these results to the examples to get global and
local sharp estimates, improving, for examlple, a result of Fefferman, Kohn and
Machedon on the Szeg\"o projection.


title:
Statistical Analysis of Galaxy Surveys - I. Robust error estimation for
  2-point clustering statistics

abstract:
  We present a test of different error estimators for 2-point clustering
statistics, appropriate for present and future large galaxy redshift surveys.
Using an ensemble of very large dark matter LambdaCDM N-body simulations, we
compare internal error estimators (jackknife and bootstrap) to external ones
(Monte-Carlo realizations). For 3-dimensional clustering statistics, we find
that none of the internal error methods investigated are able to reproduce
neither accurately nor robustly the errors of external estimators on 1 to 25
Mpc/h scales. The standard bootstrap overestimates the variance of xi(s) by
~40% on all scales probed, but recovers, in a robust fashion, the principal
eigenvectors of the underlying covariance matrix. The jackknife returns the
correct variance on large scales, but significantly overestimates it on smaller
scales. This scale dependence in the jackknife affects the recovered
eigenvectors, which tend to disagree on small scales with the external
estimates. Our results have important implications for the use of galaxy
clustering in placing constraints on cosmological parameters. For example, in a
2-parameter fit to the projected correlation function, we find that the
standard bootstrap systematically overestimates the 95% confidence interval,
while the jackknife method remains biased, but to a lesser extent. The scatter
we find between realizations, for Gaussian statistics, implies that a 2-sigma
confidence interval, as inferred from an internal estimator, could correspond
in practice to anything from 1-sigma to 3-sigma. Finally, by an oversampling of
sub-volumes, it is possible to obtain bootstrap variances and confidence
intervals that agree with external error estimates, but it is not clear if this
prescription will work for a general case.


title: The Orbit Group of a Quandle

abstract:
  We define the notion of the orbit group of a quandle via its connectivity and
compute the orbit groups for some basic quandles. We also show that the orbit
group counts the number of orbits of certain quandles.


title:
Peculiar Red Nova V838 Mon: Accretion and Interaction in a Wide Binary
  System after Explosion of Its Companion

abstract:
  We report the results of recent multicolor photometry and medium resolution
spectroscopy of V838 Mon taken in 2007-2008. In the eclipse-like event in
December 2006, the hot B3V type companion disappeared. The event accompanied by
strengthening emission [FeII]/FeII lines in the spectra. We explain this event
as the formation of temporal short-lived accretion disc around the hot
companion. Later, in February 2007 the hot star reappeared in its full
brightness, but disappeared again for a long time since September 2007. This is
the engulf of B3V companion by expanding remnant of 2002 outburst. We assume
that the thick accretion disc has formed around B type companion which is
moving now inside the envelope of the cool star. There is some evidence of
heating this disc and/or cool star envelope. We estimated the radius of
expanding cool remnant in December, 2006 of about 150 A.U. or 30000 solar
radii.


title: Dynamics of Water Entry

abstract:
  The hydrodynamics associated with water-entry of spheres can be highly
variable with respect to the material and kinematic properties of the sphere.
This series of five fluid dynamics videos illustrates several subtle but
interesting variations. The first series of videos contrasts the nature of
impact between a hydrophilic and hydrophobic sphere, and illustrates how
surface coating can affect whether or not an air cavity is formed. The second
video series illustrates how spin and surface treatments can alter the splash
and cavity formation following water entry. The spinning sphere causes a wedge
of fluid to be drawn into the cavity due to the no-slip condition and follows a
curved trajectory. The non-spinning sphere has two distinct surface treatments
on the left and right hemispheres: the left hemisphere is hydrophobic and the
right hemisphere is hydrophilic . Interestingly, the cavity formation for the
half-and-half sphere has many similarities to that of the spinning sphere
especially when viewed from above. The third video series compares two
millimetric nylon spheres impacting at slightly different impact speeds (Uo =
40 and 45 cm/s); the faster sphere fully penetrates the free surface, forming a
cavity, whereas the slower sphere does not. The fourth series shows the
instability of an elongated water-entry cavity formed by a millimetric steel
sphere with a hydrophobic coating impacting at Uo = 600 cm/s. The elongated
cavity forms multiple pinch-off points along its decent. Finally, a millimetric
steel sphere with a hydrophobic coating breaks the free surface with an impact
speed of Uo = 350 cm/s. The cavity pinches-off below the surface, generating a
Worthington jet that pinches into droplets owing to the Rayleigh-Plateau
instability.


title: Implications of spin vortex scenario for 1/8-doped lanthanum cuprates

abstract:
  Superlattice of spin vortices has been proposed in an earlier article as an
alternative to the stripe interpretation of spin modulations in 1/8-doped
lanthanum cuprates. The present article addresses several additional
characteristics of the spin vortex lattice, namely: (i) the nature of extended
charge states; (ii) the position of neutron spin peaks as a function of doping;
and (iii) the absence of higher order spin harmonics. All these characteristics
afford straightforward connection to the experimental results produced by
angle-resolved photoemission spectroscopy, resistivity measurements, and
neutron scattering.


title:
High-temperature interface superconductivity between metallic and
  insulating cuprates

abstract:
  High-temperature superconductivity confined to nanometer-size interfaces has
been a long standing goal because of potential applications^{1,2} and the
opportunity to study quantum phenomena in reduced dimensions^{3,4}. However,
this is a challenging target: in conventional metals the high electron density
restricts interface effects such as carrier depletion/accumulation to a region
much narrower than the coherence length, the scale necessary for
superconductivity to occur. In contrast, in copper oxides the carrier density
is low while the critical temperature (T_c) is high and the coherence length
very short; so, this provides a breakthrough opportunity but at a price: the
interface must be atomically perfect. Here we report on superconductivity in
bilayers consisting of an insulator (La_2CuO_4) and a metal
(La_{1.55}Sr_{0.45}CuO_{4}), neither of which is superconducting in isolation.
However, in bilayers T_c is either ~15 K or ~30 K, depending on the layering
sequence. This highly robust phenomenon is confined within 2-3 nm from the
interface. If such a bilayer is exposed to ozone, T_c exceeds 50 K and this
enhanced superconductivity is also shown to originate from the interface layer
about 1-2 unit cell thick. Enhancement of T_c in bilayer systems was observed
previously^5 but the essential role of the interface was not recognized at the
time. Our results demonstrate that engineering artificial heterostructures
provides a novel, unconventional way to fabricate stable, quasi two-dimensional
high T_c phases and to significantly enhance superconducting properties in
known or new superconductors.


title:
Matrix solutions of a noncommutative KP equation and a noncommutative
  mKP equation

abstract:
  Matrix solutions of a noncommutative KP and a noncommutative mKP equation
which can be expressed as quasideterminants are discussed. In particular, we
investigate interaction properties of two-soliton solutions.


title:
Positron/Gamma-Ray Signatures of Dark Matter Annihilation and Big-Bang
  Nucleosynthesis

abstract:
  The positron excess observed by the PAMELA experiment may come from dark
matter annihilation, if the annihilation cross section is large enough. We show
that the dark matter annihilation scenarios to explain the positron excess may
also be compatible with the discrepancy of the cosmic lithium abundances
between theory and observations. The wino-like neutralino in the supersymmetric
standard model is a good example for it. This scenario may be confirmed by
Fermi satellite experiment.


title:
The Distribution of the Domination Number of Class Cover Catch Digraphs
  for Non-uniform One-dimensional Data

abstract:
  For two or more classes of points in $\R^d$ with $d \ge 1$, the class cover
catch digraphs (CCCDs) can be constructed using the relative positions of the
points from one class with respect to the points from the other class. The
CCCDs were introduced by (Priebe, DeVinney, and Mar-chette, (2001). On the
distribution of the domination number of random class catch cover di-graphs.
Statistics and Probability Letters, 55:239-246) who investigated the case of
two classes, $\X$ and $\Y$. They calculated the exact (finite sample)
distribution of the domination number of the CCCDs based on $\X$ points
relative to $\Y$ points both of which were uniformly distri-buted on a bounded
interval. We investigate the distribution of the domination number of the CCCDs
based on data from non-uniform $\X$ points on an interval with end points from
$\Y$. Then we extend these calculations for multiple $\Y$ points on bounded
intervals.


title: Galilean equations for massless fields

abstract:
  Galilei-invariant equations for massless fields are obtained via contractions
of relativistic wave equations. It is shown that the collection of
non-equivalent Galilei-invariant wave equations for massless fields with spin
equal 1 and 0 is very reach and corresponds to various contractions of the
representations of the Lorentz group to those of the Galilei one. It describes
many physically consistent systems, e.g., those of electromagnetic fields in
various media or Galilean Chern-Simon models. Finally, classification of all
linear and a big group of non-linear Galilei-invariant equations for massless
fields is presented.


title: Kahler-Ricci flow on stable Fano manifolds

abstract:
  We study the Kahler-Ricci flow on Fano manifolds. We show that if the
curvature is bounded along the flow and if the manifold is K-polystable and
asymptotically Chow semistable, then the flow converges exponentially fast to a
Kahler-Einstein metric.


title:
First measurements of J/Psi decays into $\Sigma^+ \bar{\Sigma}^-$ and
  $\Xi^0 \bar{\Xi}^0$

abstract:
  Based on 58 million J/Psi events collected with the BESII detector at the
BEPC, the baryon pair processes J/Psi to $\Sigma^+ \bar{\Sigma}^-$ and J/Psi to
$\Xi^0 \bar{\Xi}^0$ are observed for the first time. The branching fractions
are measured to be ${\cal B}(J/Psi to \Sigma^+ \bar{\Sigma}^-)=(1.50\pm 0.10\pm
0.22)\times 10^{-3}$ and ${\cal B}(J/Psi to \Xi^0 \bar{\Xi}^0)=(1.20\pm 0.12\pm
0.21)\times 10^{-3}$, where the first errors are statistical and the second
ones are systematic.


title:
A search for spectroscopic binaries in the galactic globular cluster M4.
  Based on 5973 individual spectra collected at VLT

abstract:
  We present a large multi-epoch high resolution spectroscopic investigation
for the search of binary candidates in the Galactic Globular Cluster (GGC) M4.
The aim of our work is the identification of the binary candidates, and the
determination of the binary fraction and of the binary radial distribution. We
present a large multi-epoch high resolution spectroscopic investigation for the
search of binary candidates in the Galactic Globular Cluster (GGC) M4. The aim
of our work is the identification of the binary candidates, and the
determination of the binary fraction and of the binary radial distribution. The
average radial velocity of the observed cluster members is
$70.29+/-0.07(+/-0.3)(+/-0.1)km/s. The search for variations in radial
velocities among the stars with multi-epoch observations yielded 57 binary star
candidates. Our radial velocity measurement accuracy allowed us to identify at
a 3sigma level binaries with radial velocity variations larger than ~0.3km/s
for the target stars with V<15, and larger than ~0.5km/s for the targets with
V>15. We identified 4 binary star candidates out of 97 observed targets inside
the core radius, and 53 candidates out of 2372 observed stars outside the core
radius. Accounting for the incompleteness affecting our survey, the lower limit
for the total binary fraction is f=3.0+/-0.3%. The lower limit for the binary
fraction in the cluster core is f=5.1+/-2.3%, while outside the core it
decreases to f=3.0+/-0.4%. Similarly, we found f=4.5+/-0.4% and f=1.8+/-0.6%
for the binary fraction inside and outside the half mass radius.


title: Intrinsic Ratchets

abstract:
  We present a generic formalism to describe Brownian motion of particles with
intrinsic asymmetry and give predictions for the drift behavior in unbiased
time-dependent force fields. Our findings are supported by molecular dynamics
simulations.


title:
Paul trapping of radioactive 6He+ions and direct observation of their
  beta-decay

abstract:
  We demonstrate that abundant quantities of short-lived beta unstable ions can
be trapped in a novel transparent Paul trap and that their decay products can
directly be detected in coincidence. Low energy 6He+ (807 ms half-life) ions
were extracted from the SPIRAL source at GANIL, then decelerated, cooled and
bunched by means of the buffer gas cooling technique. More than 10^8 ions have
been stored over a measuring period of six days and about 10^5 decay
coincidences between the beta particles and the 6Li^{++} recoiling ions have
been recorded. The technique can be extended to other short-lived species,
opening new possibilities for trap assisted decay experiments.


title: The energy dependence of the electric dipole strength in heavy nuclei

abstract:
  On the basis of new photon scattering measurements and a reevaluation of
average neutron resonance capture data we investigate how well Lorentzians
adjusted to photo-neutron data in the giant dipole resonances give a good
description of the photon strength also below the neutron threshold. If
deformation effects are properly taken into account this is verified down to
about 5 MeV for various nuclei with A>80 such that the previously employed
differentiation between deformed and non-deformed nuclei is no longer
necessary.


title:
A consistent solution for the velocity field and mass-loss rate of
  massive stars

abstract:
  Stellar winds are an important aspect of our understanding of the evolution
of massive stars and their input into the interstellar medium. Here we present
solutions for the velocity field and mass-loss rates for stellar outflows as
well as for the case of mass accretion through the use of the so-called Lambert
W-function. For the case of a radiation-driven wind, the velocity field is
obtained analytically using a parameterised description for the line
acceleration that only depends on radius, which we obtain from Monte-Carlo
multi-line radiative transfer calculations. In our form of the equation of
motion the critical point is the sonic point. We also derive an approximate
analytical solution for the supersonic flow which closely resembles our exact
solution. For the simultaneous solution of the mass-loss rate and velocity
field, we describe a new iterative method. We apply our theoretical expressions
and our iterative method to the stellar wind from a typical O5-V main sequence
star, and find good agreement with empirical values. Our computations represent
a self-consistent mass-loss calculation including the effect of multi-line
scattering for an O-type star, opening up the possibility of applying Monte
Carlo mass-loss calculations in regions of the Universe for which empirical
constraints cannot be readily obtained.


title: A Spitzer search for cold dust within globular clusters

abstract:
  Globular cluster stars evolving off the main sequence are known to lose mass,
and it is expected that some of the lost material should remain within the
cluster as an intracluster medium (ICM). Most attempts to detect such an ICM
have been unsuccessful. The Multiband Imaging Photometer for Spitzer on the
Spitzer Space Telescope was used to observe eight Galactic globular clusters in
an attempt to detect the thermal emission from ICM dust. Most clusters do not
have significant detections at 70 microns; one cluster, NGC 6341, has tentative
evidence for the presence of dust, but 90 micron observations do not confirm
the detection. Individual 70 micron point sources which appear in several of
the cluster images are likely to be background galaxies. The inferred dust mass
and upper limits are < 4e-4 solar masses, well below expectations for cluster
dust production from mass loss in red and asymptotic giant branch stars. This
implies that either globular cluster dust production is less efficient, or that
ICM removal or dust destruction is more efficient, than previously believed. We
explore several possibilities for ICM removal and conclude that present data do
not yet permit us to distinguish between them.


title: Characteristic Evolution and Matching

abstract:
  I review the development of numerical evolution codes for general relativity
based upon the characteristic initial value problem. Progress in characteristic
evolution is traced from the early stage of 1D feasibility studies to 2D
axisymmetric codes that accurately simulate the oscillations and gravitational
collapse of relativistic stars and to current 3D codes that provide pieces of a
binary black hole spacetime. Cauchy codes have now been successful at
simulating all aspects of the binary black hole problem inside an artificially
constructed outer boundary. A prime application of characteristic evolution is
to extend such simulations to null infinity where the waveform from the binary
inspiral and merger can be unambiguously computed. This has now been
accomplished by Cauchy-characteristic extraction, where data for the
characteristic evolution is supplied by Cauchy data on an extraction worldtube
inside the artificial outer boundary. The ultimate application of
characteristic evolution is to eliminate the role of this outer boundary by
constructing a global solution via Cauchy-characteristic matching. Progress in
this direction is discussed.


title: Unsatisfiable (k,(4*2^k/k))-CNF formulas

abstract:
  A boolean formula in a conjuctive normal form is called a (k,s)-formula if
every clause contains exactly k variables and every variable occurs in at most
s clauses. We prove the existence of a (k, 4 * (2^k/k))-CNF formula which is
unsatisfiable.


title:
Elliptic solutions of isentropic ideal compressible fluid flow in (3+1)
  dimensions

abstract:
  A modified version of the conditional symmetry method, together with the
classical method, is used to obtain new classes of elliptic solutions of the
isentropic ideal compressible fluid flow in (3+1) dimensions. We focus on those
types of solutions which are expressed in terms of the Weierstrass P-functions
of Riemann invariants. These solutions are of special interest since we show
that they remain bounded even when these invariants admit the gradient
catastrophe. We describe in detail a procedure for constructing such classes of
solutions. Finally, we present several examples of an application of our
approach which includes bumps, kinks and multi-wave solutions.


title: Dispersive representation of K -> 3 pi amplitudes and cusps

abstract:
  The NA48/2 collaboration has shown clear experimental evidence for a cusp in
the data for K -> pi pi^0 pi^0. This effect can be used to extract information
on the pi-pi scattering lengths. We address this issue using a two-loop
dispersive construction of pi pi -> pi pi and K -> pi pi pi amplitudes in the
presence of isospin breaking.


title: Observation of a multiferroic critical end point

abstract:
  The study of abrupt increases in magnetization with magnetic field known as
metamagnetic transitions has opened a rich vein of new physics in itinerant
electron systems, including the discovery of quantum critical end points with a
marked propensity to develop new kinds of order. However, the electric analogue
of the metamagnetic critical end point, a "metaelectric" critical end point has
not yet been realized. Multiferroic materials wherein magnetism and
ferroelectricity are cross-coupled are ideal candidates for the exploration of
this novel possibility using magnetic-field (\emph{H}) as a tuning parameter.
Herein, we report the discovery of a magnetic-field-induced metaelectric
transition in multiferroic BiMn$_{2}$O$_{5}$ in which the electric polarization
(\emph{P}) switches polarity along with a concomitant Mn spin-flop transition
at a critical magnetic field \emph{H}$_{\rm c}$. The simultaneous metaelectric
and spin-flop transitions become sharper upon cooling, but remain a continuous
crossover even down to 0.5 K. Near the \emph{P}=0 line realized at
$\mu_{0}$\emph{H}$_{\rm c}$$\approx$18 T below 20 K, the dielectric constant
($\varepsilon$) increases significantly over wide field- and temperature
(\emph{T})-ranges. Furthermore, a characteristic power-law behavior is found in
the \emph{P}(\emph{H}) and $\varepsilon$(\emph{H}) curves at \emph{T}=0.66 K.
These findings indicate that a magnetic-field-induced metaelectric critical end
point is realized in BiMn$_2$O$_5$ near zero temperature.


title: Strong solutions of a class of SDEs with jumps

abstract:
  We study a class of stochastic integral equations with jumps under
non-Lipschitz conditions. We use the method of Euler approximations to obtain
the existence of the solution and give some sufficient conditions for the
strong uniqueness.


title:
Mapping of 2+1-dimensional Kardar-Parisi-Zhang growth onto a driven
  lattice gas model of dimer

abstract:
  We show that a 2+1 dimensional discrete surface growth model exhibiting
Kardar-Parisi-Zhang (KPZ) class scaling can be mapped onto a two dimensional
conserved lattice gas model of directed dimers. In case of KPZ height
anisotropy the dimers follow driven diffusive motion. We confirm by numerical
simulations that the scaling exponents of the dimer model are in agreement with
those of the 2+1 dimensional KPZ class. This opens up the possibility of
analyzing growth models via reaction-diffusion models, which allow much more
efficient computer simulations.


title:
Lowering Effective Coordination Promotes Adsorption of NO on Rh(100) and
  Rh/MgO(100)surfaces

abstract:
  We have studied the adsorption of NO, and the coadsorption of N and O, on
four physical and hypothetical systems: unstrained and strained Rh(100)
surfaces and monolayers of Rh atoms on strained and unstrained MgO(100)
surfaces. We find that as we go from Rh(100) to Rh/Mg0(100), via the other two
hypothetical systems, the effective coordination progressively decreases, the
$d$-band narrows and its center shifts closer to the Fermi level, and the
strength of adsorption and co-adsorption increases. Both strain and the
presence of the oxide substrate contribute significantly to this. However,
charge-transfer is found to play a negligible role, due to a cancelling out
between donation and back-donation processes. Our results suggest that lowering
effective coordination of Rh catalysts by strain, roughening or the use of
inert substrates might improve reaction rates for the reduction of NO to N$_2$.


title:
Quasiparticle diffusion based heating in superconductor tunneling
  micro-coolers

abstract:
  In a hybrid Superconductor - Insulator - Normal metal tunnel junction biased
just below the gap, the extraction of hot electrons out of the normal metal
results in electronic cooling effect. The quasiparticles injected in the
superconductor accumulate near the tunnel interface, thus increasing the
effective superconductor temperature. We propose a simple model for the
diffusion of excess quasiparticles in a superconducting strip with an
additional trap junction. This diffusion model has a complete analytic
solution, which depends on experimentally accessible parameters. We find that
the accumulated quasiparticles near the junction reduce the efficiency of the
device. This study is also relevant to more general situations making use of
superconducting tunnel junctions, as low temperature detectors.


title:
Reidemeister torsion for linear representations and Seifert surgery on
  knots

abstract:
  We study an invariant of a 3-manifold which consists of Reidemeister torsion
for linear representations which pass through a finite group. We show a Dehn
surgery formula on this invariant and compute that of a Seifert manifold over
$S^2$. As a consequence we obtain a necessary condition for a result of Dehn
surgery along a knot to be Seifert fibered, which can be applied even in a case
where abelian Reidemeister torsion gives no information.


title: VERITAS Observations of Extragalactic Non-Blazars

abstract:
  During the 2007/2008 season, VERITAS was used for observations at E>200 GeV
of several extragalactic non-blazar objects such as galaxy clusters, starburst
and interacting galaxies, dwarf galaxies, and nearby galaxies. In these
proceedings, we present preliminary results from our observations of dwarf
galaxies and M87. Results from observation of other non-blazar sources are
presented in separate papers in the proceedings.


title:
Ground-based CCD astrometry with wide field imagers. III. WFI@2.2m
  proper-motion catalog of the globular cluster omega Centauri

abstract:
  Omega Centauri is the most well studied Globular Cluster because of its
numerous puzzling features. Intensive spectroscopic follow-up observing
campaigns targeting stars at different positions on the color-magnitude diagram
promises to clarify some of these peculiarities. To able to target cluster
members reliably during spectroscopic surveys and both spatial and radial
distributions in the cluster outskirts without including field stars, a high
quality proper-motion catalog of omega Cen and membership probability
determination are required. The only available wide field proper-motion catalog
of omega Cen is derived from photographic plates, and only for stars brighter
than B~16. Using ESO archive data, we create a new, CCD-based, proper-motion
catalog for this cluster, extending to B~20. We used the high precision
astrometric software developed specifically for data acquired by WFI@2.2m
telescope and presented in the first paper of this series. We achieved a good
cluster-field separation with a temporal base-line of only four years. We
corrected our photometry for sky-concentration effects. We provide calibrated
photometry for UBVRI wide-band data plus narrow-band filter data centered on
H_alpha for almost 360 000 stars. We can confirm that the omega Cen metal-poor
and the metal-rich components have the same proper motion, and demonstrate that
the metal-intermediate component in addition exhibits the same mean motion as
the other RGB stars. We provided membership probability determination for
published omega Cen variable star catalogs. Our catalog extends the
proper-motion measurements to fainter than the cluster turn-off luminosity, and
covers a wide area (~33'x33') around the center of omega Cen. Our catalog is
now electronically available to the astronomical community.


title: An alternative S-matrix for N=6 Chern-Simons theory ?

abstract:
  We have recently proposed an S-matrix for the planar limit of the N=6
superconformal Chern-Simons theory of Aharony, Bergman, Jafferis and Maldacena
which leads to the all-loop Bethe ansatz equations conjectured by Gromov and
Vieira. An unusual feature of this proposal is that the scattering of A and B
particles is reflectionless. We consider here an alternative S-matrix, for
which A-B scattering is not reflectionless. We argue that this S-matrix does
not lead to the Bethe ansatz equations which are consistent with perturbative
computations.


title: Photodesorption of water ice: a molecular dynamics study

abstract:
  Absorption of ultraviolet radiation by water ice coating interstellar grains
can lead to dissociation and desorption of the ice molecules. These processes
are thought to be important in the gas-grain chemistry in molecular clouds and
protoplanetary disks, but very few quantitative studies exist. We compute the
photodesorption efficiencies of amorphous water ice and elucidate the
mechanisms by which desorption occurs. Classical molecular dynamics
calculations were performed for a compact amorphous ice surface at 10 K thought
to be representative of interstellar ice. Dissociation and desorption of H2O
molecules in the top six monolayers are considered following absorption into
the first excited electronic state with photons in the 1300-1500 Angstrom
range. The trajectories of the H and OH photofragments are followed until they
escape or become trapped in the ice. The probability for H2O desorption per
absorbed UV photon is 0.5-1% in the top three monolayers, then decreases to
0.03% in the next two monolayers, and is negligible deeper into the ice. The
main H2O removal mechanism in the top two monolayers is through separate
desorption of H and OH fragments. Removal of H2O molecules from the ice, either
as H2O itself or its products, has a total probability of 2-3% per absorbed UV
photon in the top two monolayers. In the third monolayer the probability is
about 1% and deeper into the ice the probability of photodesorption falling to
insignificant numbers. The probability of any removal of H2O per incident
photon is estimated to be 3.7x10^-4, with the probability for photodesorption
of intact H2O molecules being 1.4x10^-4 per incident photon. When no desorption
occurs, the H and OH products can travel up to 70 and 60 Angstroms inside or on
top of the surface during which they can react with other species.


title:
Evolution of the Color-Magnitude Relation in Galaxy Clusters at z ~1
  from the ACS Intermediate Redshift Cluster Survey

abstract:
  We apply detailed observations of the Color-Magnitude Relation (CMR) with the
ACS/HST to study galaxy evolution in eight clusters at z~1. The early-type red
sequence is well defined and elliptical and lenticular galaxies lie on similar
CMRs. We analyze CMR parameters as a function of redshift, galaxy properties
and cluster mass. For bright galaxies (M_B < -21mag), the CMR scatter of the
elliptical population in cluster cores is smaller than that of the S0
population, although the two become similar at faint magnitudes. While the
bright S0 population consistently shows larger scatter than the ellipticals,
the scatter of the latter increases in the peripheral cluster regions. If we
interpret these results as due to age differences, bright elliptical galaxies
in cluster cores are on average older than S0 galaxies and peripheral
elliptical galaxies (by about 0.5Gyr). CMR zero point, slope, and scatter in
the (U-B)_z=0 rest-frame show no significant evolution out to redshift z~1.3
nor significant dependence on cluster mass. Two of our clusters display CMR
zero points that are redder (by ~2sigma) than the average (U-B)_z=0 of our
sample. We also analyze the fraction of morphological early-type and late-type
galaxies on the red sequence. We find that, while in the majority of the
clusters most (80% to 90%) of the CMR population is composed of early-type
galaxies, in the highest redshift, low mass cluster of our sample, the CMR
late-type/early-type fractions are similar (~50%), with most of the late-type
population composed of galaxies classified as S0/a. This trend is not
correlated with the cluster's X-ray luminosity, nor with its velocity
dispersion, and could be a real evolution with redshift.


title: Axisymmetric smoothed particle hydrodynamics with self-gravity

abstract:
  The axisymmetric form of the hydrodynamic equations within the smoothed
particle hydrodynamics (SPH) formalism is presented and checked using idealized
scenarios taken from astrophysics (free fall collapse, implosion and further
pulsation of a sun-like star), gas dynamics (wall heating problem, collision of
two streams of gas) and inertial confinement fusion (ICF, -ablative implosion
of a small capsule-). New material concerning the standard SPH formalism is
given. That includes the numerical handling of those mass points which move
close to the singularity axis, more accurate expressions for the artificial
viscosity and the heat conduction term and an easy way to incorporate
self-gravity in the simulations. The algorithm developed to compute gravity
does not rely in any sort of grid, leading to a numerical scheme totally
compatible with the lagrangian nature of the SPH equations.


title:
On the conditions for discrimination between quantum states with minimum
  error

abstract:
  We provide a simple proof for the necessity of conditions for discriminating
with minimum error between a known set of quantum states.


title: Accuracy of bound-state form factors extracted from dispersive sum rules

abstract:
  We discuss the extraction of form factors from three-point sum rules making
use of harmonic-oscillator model, where we derive the exact expression for the
relevant correlator. We determine the form factor of the ground state by the
standard procedures adopted in the method of sum rules, and compare the
obtained results with the known exact values. We show that the uncontrollable
uncertainty in the extracted value of the form factor is typically much larger
than that for the decay constant. In the example considered, we find the
uncontrolled systematic error in the extracted form factor to exceed the 10%
level.


title: Operator extensions of Hua's inequality

abstract:
  We give an extension of Hua's inequality in pre-Hilbert $C^*$-modules without
using convexity or the classical Hua's inequality. As a consequence, some known
and new generalizations of this inequality are deduced. Providing a Jensen
inequality in the content of Hilbert $C^*$-modules, another extension of Hua's
inequality is obtained. We also present an operator Hua's inequality, which is
equivalent to operator convexity of given continuous real function.


title: Look-Ahead Benchmark Bias in Portfolio Performance Evaluation

abstract:
  Performance of investment managers are evaluated in comparison with
benchmarks, such as financial indices. Due to the operational constraint that
most professional databases do not track the change of constitution of
benchmark portfolios, standard tests of performance suffer from the "look-ahead
benchmark bias," when they use the assets constituting the benchmarks of
reference at the end of the testing period, rather than at the beginning of the
period. Here, we report that the "look-ahead benchmark bias" can exhibit a
surprisingly large amplitude for portfolios of common stocks (up to 8% annum
for the S&P500 taken as the benchmark) -- while most studies have emphasized
related survival biases in performance of mutual and hedge funds for which the
biases can be expected to be even larger. We use the CRSP database from 1926 to
2006 and analyze the running top 500 US capitalizations to demonstrate that
this bias can account for a gross overestimation of performance metrics such as
the Sharpe ratio as well as an underestimation of risk, as measured for
instance by peak-to-valley drawdowns. We demonstrate the presence of a
significant bias in the estimation of the survival and look-ahead biases
studied in the literature. A general methodology to test the properties of
investment strategies is advanced in terms of random strategies with similar
investment constraints.


title: Simulating quantum systems using real Hilbert spaces

abstract:
  We develop a means of simulating the evolution and measurement of a
multipartite quantum state under discrete or continuous evolution using another
quantum system with states and operators lying in a real Hilbert space. This
extends previous results which were unable to simulate local evolution and
measurements with local operators and was limited to discrete evolution. We
also detail applications to Bell inequalities and self-testing of quantum
apparatus.


title: Extremal metrics on del Pezzo threefolds

abstract:
  We prove the existence of Kahler-Einstein metrics on a nonsingular section of
the Grassmannian $\mathrm{Gr}(2, 5)\subset\mathbb{P}^9$ by a linear subspace of
codimension 3, and the Fermat hypersurface of degree 6 in
$\mathbb{P}(1,1,1,2,3)$. We also show that a global log canonical threshold of
the Mukai--Umemura variety is equal to 1/2.


title: Survey of excited state neutron spectroscopic factors for Z=8-28 nuclei

abstract:
  We have extracted 565 neutron spectroscopic factors of sd and fp shell nuclei
by systematically analyzing more than 2000 measured (d,p) angular
distributions. We are able to compare 125 of the extracted spectroscopic
factors to values predicted by large-basis shell-model calculations and
evaluate the accuracies of spectroscopic factors predicted by different
shell-model interactions in these regions. We find that the spectroscopic
factors predicted for most excited states of sd-shell nuclei using the latest
USDB or USDA interactions agree with the experimental values. For fp shell
nuclei, the inability of the current models to account for the core excitation
and fragmentation of the states leads to considerable discrepancies. In
particular, the agreement between data and shell-model predictions for Ni
isotopes is not better than a factor of two using either the GXPF1A or the XT
interaction.


title:
Electronic structure of the SrTiO$_3$/LaAlO$_3$ interface revealed by
  resonant soft x-ray scattering

abstract:
  We investigated the electronic structure of the SrTiO$_3$/LaAlO$_3$
superlattice (SL) by resonant soft x-ray scattering. The (003) peak, which is
forbidden for our "ideal" SL structure, was observed at all photon energies,
indicating reconstruction at the interface. From the peak position analyses
taking into account the effects of refraction, we obtained evidence for
electronic reconstruction of Ti 3d and O $2p$ states at the interface. From
reflectivity analyses, we concluded that the AlO$_2$/LaO/TiO$_2$/SrO and the
TiO$_2$/SrO/AlO$_2$/LaO interfaces are quite different, leading to highly
asymmetric properties.


title: On a linear form for Catalan's constant

abstract:
  It is shown how Andrews' multidimensional extension of Watson's
transformation between a very-well-poised $_8\phi_7$-series and a balanced
$_4\phi_3$-series can be used to give a straightforward proof of a conjecture
of Zudilin and the second author on the arithmetic behaviour of the
coefficients of certain linear forms of 1 and Catalan's constant. This proof is
considerably simpler and more stream-lined than the first proof, due to the
second author.


title:
Unitarity, Lorentz invariance and causality in Lee-Wick theories: An
  asymptotically safe completion of QED

abstract:
  We revisit the previously unsolved problems of ensuring Lorentz invariance
and non-perturbative unitarity in Lee-Wick theories. We base our discussion on
an ultraviolet completion of QED by Lee-Wick ghost fields, which is argued to
be asymptotically safe. We argue that as long as the state space is based upon
a suitable choice of distributions of a type invented by Gel'fand and Shilov,
the Lee-Wick ghosts can be eliminated while preserving Lorentz invariance to
produce a unitary theory. The method for eliminating ghosts is in principle
non-perturbatively well-defined, in contrast with some previous proposals. We
also point out a second, independent mechanism for producing a unitary theory,
based on a covariant constraint on the maximum four-momentum, which would imply
an amusing connection, based on naturalness, between the coupling constant and
the hierarchy of scales in the theory. We further emphasize that the resulting
theory is causal, and point out some analogies between between the behaviour of
Lee-Wick ghost degrees of freedom and black holes.


title:
Gravitational perturbations of Schwarzschild spacetime at null infinity
  and the hyperboloidal initial value problem

abstract:
  We study gravitational perturbations of Schwarzschild spacetime by solving a
hyperboloidal initial value problem for the Bardeen-Press equation.
Compactification along hyperboloidal surfaces in a scri-fixing gauge allows us
to have access to the gravitational waveform at null infinity in a general
setup. We argue that this hyperboloidal approach leads to a more accurate and
efficient calculation of the radiation signal than the common approach where a
timelike outer boundary is introduced. The method can be generalized to study
perturbations of Kerr spacetime using the Teukolsky equation.


title: A likely optical counterpart of the G292.0+1.8 pulsar wind nebula

abstract:
  G292.0+1.8 is the Cas A-like supernova remnant containing the young pulsar
PSR J1124-5916, which powers a compact torus-like pulsar wind nebula with a jet
visible in X-rays. We have performed deep optical observations of the pulsar
field to detect the optical counterpart of the pulsar and its nebula. The
observations were carried out using the direct imaging mode of FORS2 at the ESO
VLT/UT1 telescope in the V, R, and I bands. We also analyzed archival images
obtained with the Chandra/ACIS-I, ACIS-S, and HRC-S in X-rays. In all three
optical bands we detect a faint elliptical nebulosity, whose brightness peak
and center position are consistent at a sub-arcsecond level with the X-ray
position of the pulsar. The field is densely packed with background stars, but
after subtraction of these stars the morphology of the object and the
orientation of its major axis appear to be in a good agreement with the
brightest inner part of the pulsar nebula torus region seen almost edge on in
X-rays. Within the nebulosity we do not resolve any point-like optical object
that could be identified with the pulsar and estimate its contribution to the
observed nebulosity flux as <~20%. Extracting the X-ray spectrum from the
physical region equivalent to the optical source position and extent and
combining that with the measured optical fluxes, we compile a tentative
multi-wavelength spectrum of the inner part of the nebula. Within uncertainties
of the interstellar extinction towards G292.0+1.8 it is reminiscent of either
the Crab or PSR B540-69 and J0205+6449 pulsar wind nebula spectra. The
position, morphology, and spectral properties of the detected nebulosity
suggest that it is the likely optical counterpart of the pulsar plus its wind
nebula system in G292.0+1.8.


title: Ramanujan congruences for a class of eta quotients

abstract:
  We consider a class of generating functions analogous to the generating
function of the partition function and establish a bound on the primes $\ell$
for which their coefficients $c(n)$ obey congruences of the form $c(\ell n + a)
\equiv 0 \pmod \ell$. We apply this result to obtain a complete
characterization of the congruences of the same form that the sequences
$c_N(n)$ satisfy, where $c_N(n)$ is defined by $ \sum_{n=0}^{\infty} c_N(n)q^n
= \prod_{n=1}^{\infty} \frac{1}{(1-q^n)(1-q^{Nn})}$. This last result answers a
question of H.-C. Chan.


title: Photometric variability of WC9 stars

abstract:
  Do some Wolf-Rayet stars owe their strong winds to something else besides
radiation pressure? The answer to this question is still not entirely obvious,
especially in certain Wolf-Rayet subclasses, mainly WN8 and WC9. Both of these
types of Wolf-Rayet stars are thought to be highly variable, as suggested by
observations, possibly due to pulsations. However, only the WN8 stars have so
far been vigorously and systematically investigated for variability. We present
here the results of a systematic survey during 3 consecutive weeks of 19
Galactic WC9 stars and 1 WC8 star for photometric variability in two optical
bands, V and I. Of particular interest are the correlated variations in
brightness and colour index in the context of carbon-dust formation, which
occurs frequently in WC9 and some WC8 stars. In the most variable case, WR76,
we used this information to derive a typical dust grain size of ~ 0.1 um.
However, most photometric variations occur at surprisingly low levels and in
fact almost half of our sample shows no significant variability at all above
the instrumental level (sigma ~ 0.005 - 0.01 mag).


title:
Aspects of Precision Calculations of Nucleon Generalized Form Factors
  with Domain Wall Fermions on an Asqtad Sea

abstract:
  In order to advance lattice calculations of moments of unpolarized, helicity,
and transversity distributions, electromagnetic form factors, and generalized
form factors of the nucleon to a new level of precision, this work investigates
several key aspects of precision lattice calculations. We calculate the number
of configurations required for constant statistical errors as a function of
pion mass, describe the coherent sink method to help achieve these statistics,
examine the statistical correlations between separate measurements, study
correlations in the behavior of form factors at different momentum transfer,
examine volume dependence, and compare mixed action results with those using
comparable dynamical domain wall configurations. We also show selected form
factor results and comment on the QCD evolution of our calculations of the
flavor non-singlet nucleon angular momentum.


title: On the gravitational angular momentum of rotating sources

abstract:
  The gravitational energy-momentum and angular momentum satisfy the algebra of
the Poincare group in the full phase space of the teleparallel equivalent of
general relativity. The expression for the gravitational energy-momentum may be
written as a surface integral in the three-dimensional spacelike hypersurface,
whereas the definition for the angular momentum is given by a volume integral.
It turns out that in practical calculations of the angular momentum of the
gravitational field generated by localized sources like rotating neutron stars,
the volume integral reduces to a surface integral, and the calculations can be
easily carried out. Similar to previous investigations in the literature, we
show that the total angular momentum is finite provided a certain asymptotic
behaviour is verified. We discuss the dependence of the gravitational angular
momentum on the frame, and argue that it is a measure of the dragging of
inertial frames.


title:
Expanding Ejecta in the Oxygen-Rich Supernova Remnant G292.0+1.8: Direct
  Measurement through Proper Motions

abstract:
  We report here the first study of proper motions of fast filaments in the
young, oxygen-rich supernova remnant G292.0+1.8, carried out using a series of
[O III] 5007 A emission-line images taken over a period of more than 21 years.
Images taken at seven epochs from 1986 to 2008, all from telescopes at the
Cerro Tololo Inter-American Observatory, show oxygen-emitting filaments,
presumably ejecta fragments, throughout most of the remnant. We have measured
the proper motions for 67 discrete filaments through two-dimensional
correlations between images from different epochs. While the motions are small,
mostly 20 to 100 milli-arcsec, they are nevertheless measurable through a
robust technique of averaging measurements from many epoch pairs. The data are
qualitatively consistent with a free-expansion model, and clearly show
systematic motions outward from a point near the center of the radio/X-ray
shell. Global fits using this model indicate an expansion center at
R.A.(2000.0) = 11:24:34.4, Dec.(2000.0) = -59:15:51, and a kinematic age of
2990+-60 years. The young pulsar PSR J1124-5916 is located 46 arcsec southeast
of the expansion center. Assuming that it was launched by the supernova, we
expect the pulsar to be moving southeastward at 16 milli-arcsec, or a
transverse velocity of 440 km/s. We find the fastest ejecta along an axis
oriented roughly N-S in the plane of the sky, suggesting that a bipolar
explosion produced G292.0+1.8, as appears to have been the case for Cas A.


title: Exceptional Sequences of Invertible Sheaves on Rational Surfaces

abstract:
  In this article we consider exceptional sequences of invertible sheaves on
smooth complete rational surfaces. We show that to every such sequence one can
associate a smooth complete toric surface in a canonical way. We use this
structural result to prove various theorems on exceptional and strongly
exceptional sequences of invertible sheaves on rational surfaces. We construct
full strongly exceptional sequences for a large class of rational surfaces. For
the case of toric surfaces we give a complete classification of full strongly
exceptional sequences of invertible sheaves.


title: There are no $\mathcal{C}^5$-Regular Pure $y$-Global Landsberg Surfaces

abstract:
  We show that there are not pure $\mathcal{C}^5$ regular y-global Landsberg
surfaced. The proof is based on the averaged connection associated with the
linear Chern's connection and the classification of irreducibles holonomies of
torsion-free affine connections. The structure consists on exausting all the
possible cases and showing that in dimension 2 Landsberg condition implies
Berwald condition.


title:
Comparison of Different Pairing Fluctuation Approaches to BCS-BEC
  Crossover

abstract:
  The subject of BCS - Bose Einstein condensation (BEC) crossover is
particularly exciting because of its realization in ultracold Fermi gases and
its possible relevance to high temperature superconductors. In the paper we
review that body of theoretical work on this subject which represents a natural
extension of the seminal papers by Leggett and by Nozieres and Schmitt-Rink
(NSR). The former addressed only the ground state, now known as the
"BCS-Leggett" wave-function and the key contributions of the latter pertain to
calculations of the superfluid transition temperature $T_c$. These two papers
have given rise to two main and, importantly, distinct, theoretical schools in
the BCS-BEC crossover literature. The first of these extends the BCS-Leggett
ground state to finite temperature and the second extends the NSR scheme away
from $T_c$ both in the superfluid and normal phases. It is now rather widely
accepted that these extensions of NSR produce a different ground state than
that first introduced by Leggett. Our analysis shows how the NSR-based approach
views the bosonic contributions more completely but it treats the fermions as
"quasi-free". By contrast, the BCS-Leggett based approach treats the fermionic
contributions more completely but it treats the bosons as "quasi-free". The NSR
based schemes approach the crossover between BCS and BEC by starting from the
BEC limit and the BCS-Leggett based scheme approaches this crossover by
starting from the BCS limit. Ultimately, one would like to combine these two
schemes. In this paper we review the strengths and weaknesses of both
approaches. To reach a full understanding, it is important in the future to
invest effort in investigating in more detail the T=0 aspects of NSR-based
theory and the $T \neq 0$ aspects of BCS-Leggett theory.

categories: cond-mat.other cond-mat.quant-gas cond-mat.str-el cond-mat.supr-con


title: Inverse Raman Scattering in Silicon

abstract:
  Stimulated Raman scattering is a well-known nonlinear process that can be
harnessed to produce optical gain in a wide variety of media. This effect has
been used to produce the first silicon-based lasers and high-gain amplifiers.
Interestingly, the Raman effect can also produce intensity-dependent nonlinear
loss through a corollary process known as inverse Raman scattering (IRS). Here,
we demonstrate IRS in silicon--a process that is substantially modified by the
presence of optically-generated free carriers--achieving attenuation levels >15
dB with a pump intensity of 4 GW/cm^2. Ironically, we find that free-carrier
absorption, the detrimental effect that suppresses other nonlinear effects in
silicon, actually facilitates IRS by delaying the onset of contamination from
coherent anti-Stokes Raman scattering. The carriers allow significant IRS
attenuation over a wide intensity range. Silicon-based IRS could be used to
produce chip-scale wavelength-division multiplexers, optical signal inverters,
and fast optical switches.


title:
Theory of Radio Frequency Spectroscopy Experiments in Ultracold Fermi
  Gases and Their Relation to Photoemission Experiments in the Cuprates

abstract:
  In this paper we present an overview of radio frequency (RF) spectroscopy in
the atomic Fermi superfluids. An ultimate goal is to suggest new directions in
the cold gas research agenda from the condensed matter perspective.Our focus is
on the experimental and theoretical literature of cold gases and photoemission
spectroscopy of the cuprates particularly as it pertains to areas of overlap.
This paper contains a systematic overview of the theory of RF spectroscopy,
both momentum integrated and momentum resolved. We discuss the effects of
traps, population imbalance, final state interactions over the entire range of
temperatures and compare theory and experiment. We show that this broad range
of phenomena can be accomodated within the BCS-Leggett description of BCS-BEC
crossover and that this scheme also captures some of the central observations
in photoemission experiments in the cuprates. In this last context, we note
that the key themes which have emerged in cuprate photoemission studies involve
characterization of the fermionic self energy, of the pseudogap and of the
effects of superconducting coherence (in passing from above to below the
superfluid transition temperature, $T_c$).These issues have a counterpart in
the cold Fermi gases and it would be most useful in future to use these atomic
systems to address these and the more sweeping question of how to describe that
anomalous superfluid phase which forms in the presence of a normal state
excitation gap.

categories: cond-mat.supr-con cond-mat.other cond-mat.quant-gas cond-mat.str-el


title: Electromagnetic two-body currents of one- and two-pion range

abstract:
  Nuclear electromagnetic currents are derived in time-ordered perturbation
theory within an effective-field-theory framework including explicit nucleons,
$\Delta$ isobars, and pions up to one loop, or N$^3$LO. The currents obtained
at N$^2$LO, {\it i.e.} ignoring loop corrections, are used in a study of
neutron radiative captures on protons and deuterons at thermal energies, and of
$A$=2 and 3 nuclei magnetic moments. The wave functions for $A$=2 are derived
from solutions of the Schr\"odinger equation with the Argonne $v_{18}$ (AV18)
or CD-Bonn (CDB) potentials, while those for $A$=3 are obtained with the
hyperspherical-harmonics-expansion method from a realistic Hamiltonian
including, in addition to the AV18 or CDB two-nucleon, also a three-nucleon
potential. With the strengths of the $\Delta$-excitation currents occurring at
N$^2$LO determined to reproduce the $n$-$p$ cross section and isovector
combination of the trinucleon magnetic moments, we find that the cross section
and photon circular polarization parameter, measured in $n$-$d$ and
$\vec{n}$-$d$ processes, are underpredicted by theory, for example the cross
section by (11--38)% as the cutoff is increased from 500 to 800 MeV. A complete
analysis of the results, in particular their large cutoff dependence, is
presented.


title: The Euler class of planar groups

abstract:
  This is an exposition of the homological classification of actions of surface
groups on the plane, in every degree of smoothness.


title:
Pullback of the Volume Form, Integrable Models in Higher Dimensions and
  Exotic Textures

abstract:
  A procedure allowing for the construction of Lorentz invariant integrable
models living in d+1 dimensional space-time and with an n dimensional target
space is provided. Here, integrability is understood as the existence of the
generalized zero-curvature formulation and infinitely many conserved
quantities. A close relation between the Lagrange density of the integrable
models and the pullback of the pertinent volume form on target space is
established. Moreover, we show that the conserved currents are Noether currents
generated by the volume preserving diffeomorphisms. Further, we show how such
models may emerge via abelian projection of some gauge theories.
  Then we apply this framework to the construction of integrable models with
exotic textures. Particularly, we consider integrable models providing exact
suspended Hopf maps i.e., solitons with a nontrivial topological charge of
pi_4(S^3).
  Finally, some families of integrable models with solitons of pi_n(S^n) type
are constructed. Infinitely many exact solutions with arbitrary value of the
topological index are found. In addition, we demonstrate that they saturate a
Bogomolny bound.


title: Anisotropic phase diagram and strong coupling effects in Ba1-xKxFe2As2

abstract:
  We present a thermodynamic study of the phase diagram of single-crystal
Ba1-xKxFe2As2 using specific heat measurements. In zero-magnetic field a clear
step in the heat capacity of deltaC/Tc = 0.1 J/f.u.K2 is observed at Tc = 34.6K
for a sample with x = 0.4. This material is characterized by extraordinarily
high slopes of the upper critical field of dHc2,c/dT= -6.5 T/K and dHc2,ab/dT=
-17.4 T/K and a surprisingly low anisotropy of gamma ~ 2.6 near Tc. A
consequence of the large field scale is the effective suppression of
superconducting fluctuations. Using thermodynamic relations we determine
Ginzburg-Landau parameters of kappac ~ 100 and kappaab ~ 260 identifying
Ba1-xKxFe2As2 as extreme type-II. The large value of the normalized
discontinuity of the slopes of the specific heat at Tc, (Tc/deltaC)times
delta(dC/dT)~ 6 indicates strong coupling effects in Ba1-xKxFe2As2.


title:
Enhanced empirical data for the fundamental diagram and the flow through
  bottlenecks

abstract:
  In recent years, several approaches for modelling pedestrian dynamics have
been proposed and applied e.g. for design of egress routes. However, so far not
much attention has been paid to their 'quantitative' validation. This
unsatisfactory situation belongs amongst others on the uncertain and
contradictory experimental data base. The fundamental diagram, i.e. the
density-dependence of the flow or velocity, is probably the most important
relation as it connects the basic parameter to describe the dynamic of crowds.
But specifications in different handbooks as well as experimental measurements
differ considerably. The same is true for the bottleneck flow. After a
comprehensive review of the experimental data base we give an survey of a
research project, including experiments with up to 250 persons performed under
well controlled laboratory conditions. The trajectories of each person are
measured in high precision to analyze the fundamental diagram and the flow
through bottlenecks. The trajectories allow to study how the way of measurement
influences the resulting relations. Surprisingly we found large deviation
amongst the methods. These may be responsible for the deviation in the
literature mentioned above. The results are of particular importance for the
comparison of experimental data gained in different contexts and for the
validation of models.


title:
Quantitative Flow Field Imaging about a Hydrophobic Sphere Impacting on
  a Free Surface

abstract:
  This fluid dynamics video shows the impact of a hydrophobic sphere impacting
a water surface. The sphere has a mass ratio of m* = 1.15, a wetting angle of
110 degrees, a diameter of 9.5 mm, and impacts the surface with a Froude number
of Fr = 9.2. The first sequence shows an impact of a sphere on the free surface
illustrating the formation of the splash crown and air cavity. The cavity grows
both in the axial and radial direction until it eventually collapses at a point
roughly half of the distance from the free surface to the sphere, which is
known as the pinch-off point. The second set of videos shows a sphere impacting
the free surface under the same conditions using Particle Image Velocimetry
(PIV) to quantify the flow field. A laser sheet illuminates the mid-plane of
the sphere, and the fluid is seeded with particles whose motion is captured by
a high-speed video camera. Velocity fields are then calculated from the images.
The video sequences from left to right depict the radial velocity, the axial
velocity, and the vorticity respectively in the flow field. The color bar on
the far left indicates the magnitude of the velocity and vorticity. All videos
were taken at 2610 fps and the PIV data was processed using a 16 x 16 window
with a 50% overlap.


title:
Fermi surface and order parameter driven vortex lattice structure
  transitions in twin-free YBa2Cu3O7

abstract:
  We report on small-angle neutron scattering studies of the intrinsic vortex
lattice (VL) structure in detwinned YBa2Cu3O7 at 2 K, and in fields up to 10.8
T. Because of the suppressed pinning to twin-domain boundaries, a new distorted
hexagonal VL structure phase is stabilized at intermediate fields. It is
separated from a low-field hexagonal phase of different orientation and
distortion by a first-order transition at 2.0(2) T that is probably driven by
Fermi surface effects. We argue that another first-order transition at 6.7(2)
T, into a rhombic structure with a distortion of opposite sign, marks a
crossover from a regime where Fermi surface anisotropy is dominant, to one
where the VL structure and distortion is controlled by the order-parameter
anisotropy.


title: Superoscillation in speckle patterns

abstract:
  Waves are superoscillatory where their local phase gradient exceeds the
maximum wavenumber in their Fourier spectrum. We consider the superoscillatory
area fraction of random optical speckle patterns. This follows from the joint
probability density function of intensity and phase gradient for isotropic
gaussian random wave superpositions. Strikingly, this fraction is 1/3 when all
the waves in the two-dimensional superposition have the same wavenumber. The
fraction is 1/5 for a disk spectrum. Although these superoscillations are weak
compared with optical fields with designed superoscillations, they are more
stable on paraxial propagation.


title: Molecular regimes in ultracold Fermi gases

abstract:
  The use of Feshbach resonances for tuning the interparticle interaction in
ultracold Fermi gases has led to remarkable developments, in particular to the
creation and Bose-Einstein condensation of weakly bound diatomic molecules of
fermionic atoms. These are the largest diatomic molecules obtained so far, with
a size of the order of thousands of angstroms. They represent novel composite
bosons, which exhibit features of Fermi statistics at short intermolecular
distances. Being highly excited, these molecules are remarkably stable with
respect to collisional relaxation, which is a consequence of the Pauli
exclusion principle for identical fermionic atoms. The purpose of this review
is to introduce theoretical approaches and describe the physics of molecular
regimes in two-component Fermi gases and Fermi-Fermi mixtures, focusing
attention on quantum statistical effects.


title:
An Improved Method for Using MgII to Estimate Black Hole Masses in
  Active Galactic Nuclei

abstract:
  We present a method for obtaining accurate black hole (BH) mass estimates
from the MgII emission line in active galactic nuclei (AGNs). Employing the
large database of AGN measurements from the Sloan Digital Sky Survey (SDSS)
presented by Shen et al., we find that AGNs in the redshift range 0.3-0.9, for
which a given object can have both H-beta and MgII line widths measured,
display a modest but correctable discrepancy in MgII-based masses that
correlates with the Eddington ratio. We use the SDSS database to estimate the
probability distribution of the true (i.e., H-beta-based) mass given a measured
MgII line width. These probability distributions are then applied to the SDSS
measurements from Shen et al. across the entire MgII-accessible redshift range
(0.3-2.2). We find that accounting for this residual correlation generally
increases the dispersion of Eddington ratios by a small factor (~0.09 dex for
the redshift and luminosity bins we consider). We continue to find that the
intrinsic distribution of Eddington ratios for luminous AGNs is extremely
narrow, 0.3-0.4 dex, as demonstrated by Kollmeier et al. Using the method we
describe, MgII emission lines can be used with confidence to obtain BH mass
estimates.