title: Propagation of field disturbances in the Yang-Mills theory

abstract:
  The propagation of field disturbances is examined in the context of the
effective Yang-Mills Lagrangian, which is intended to be applied to QCD
systems. It is shown that birefringence phenomena can occur in such systems
provided some restrictive conditions, as causality, are fulfilled. Possible
applications to phenomenology are addressed.


title:
Phylogenetic information complexity: Is testing a tree easier than
  finding it?

abstract:
  Phylogenetic trees describe the evolutionary history of a group of
present-day species from a common ancestor. These trees are typically
reconstructed from aligned DNA sequence data. In this paper we analytically
address the following question: is the amount of sequence data required to
accurately reconstruct a tree significantly more than the amount required to
test whether or not a candidate tree was the `true' tree? By `significantly',
we mean that the two quantities behave the same way as a function of the number
of species being considered. We prove that, for a certain type of model, the
amount of information required is not significantly different; while for
another type of model, the information required to test a tree is independent
of the number of leaves, while that required to reconstruct it grows with this
number. Our results combine probabilistic and combinatorial arguments.


title:
Stability and interactions of nanocolloids at fluid interfaces: effects
  of capillary waves and line tensions

abstract:
  We analyze the effective potential for nanoparticles trapped at a fluid
interface within a simple model which incorporates surface and line tensions as
well as a thermal average over interface fluctuations (capillary waves). For a
single colloid, a reduced steepness of the potential well hindering movements
out of the interface plane compared to rigid interface models is observed, and
an instability of the capillary wave partition sum in case of negative line
tensions is pointed out. For two colloids, averaging over the capillary waves
leads to an effective Casimir--type interaction which is long--ranged,
power-like in the inverse distance but whose power sensitively depends on
possible restrictions of the colloid degress of freedom. A nonzero line tension
leads to changes in the magnitude but not in the functional form of the
effective potential asymptotics.


title:
Thermohaline mixing and gravitational settling in carbon-enhanced
  metal-poor stars

abstract:
  We investigate the formation of carbon-enhanced metal-poor (CEMP) stars via
the scenario of mass transfer from a carbon-rich asymptotic giant branch (AGB)
primary to a low-mass companion in a binary system. We explore the extent to
which material accreted from a companion star becomes mixed with that of the
recipient, focusing on the effects of thermohaline mixing and gravitational
settling. We have created a new set of asymptotic giant branch models in order
to determine what the composition of material being accreted in these systems
will be. We then model a range of CEMP systems by evolving a grid of models of
low-mass stars, varying the amount of material accreted by the star (to mimic
systems with different separations) and also the composition of the accreted
material (to mimic accretion from primaries of different mass). We find that
with thermohaline mixing alone, the accreted material can become mixed with
between 16 and 88 per cent of the pristine stellar material of the accretor,
depending on the mass accreted and the composition of the material. If we
include the effects of gravitational settling, we find that thermohaline mixing
can be inhibited and, in the case that only a small quantity of material is
accreted, can be suppressed almost completely.


title: New Mechanics of Generic Musculo-Skeletal Injury

abstract:
  Prediction and prevention of musculo-skeletal injuries is an important aspect
of preventive health science. Using as an example a human knee joint, this
paper proposes a new coupled-loading-rate hypothesis, which states that a
generic cause of any musculo-skeletal injury is a Euclidean jolt, or
SE(3)-jolt, an impulsive loading that hits a joint in several coupled
degrees-of-freedom simultaneously. Informally, it is a rate-of-change of joint
acceleration in all 6-degrees-of-freedom simultaneously, times the
corresponding portion of the body mass. In the case of a human knee, this
happens when most of the body mass is on one leg with a semi-flexed knee -- and
then, caused by some external shock, the knee suddenly `jerks'; this can happen
in running, skiing, sports games (e.g., soccer, rugby) and various
crashes/impacts. To show this formally, based on the previously defined
covariant force law and its application to traumatic brain injury (Ivancevic,
2008), we formulate the coupled Newton--Euler dynamics of human joint motions
and derive from it the corresponding coupled SE(3)-jolt dynamics of the joint
in case. The SE(3)-jolt is the main cause of two forms of discontinuous joint
injury: (i) mild rotational disclinations and (ii) severe translational
dislocations. Both the joint disclinations and dislocations, as caused by the
SE(3)-jolt, are described using the Cosserat multipolar viscoelastic continuum
joint model.
  Keywords: musculo-skeletal injury, coupled-loading--rate hypothesis, coupled
Newton-Euler dynamics, Euclidean jolt dynamics, joint dislocations and
disclinations


title:
Closing the gap of secure quantum key rate with the Heralded
  Pair-Coherent States

abstract:
  In this paper, we investigate the long-standing gap of quantum key rate
between the Weak Coherent Pulse (WCP) and Heralded Single Photon Sources(HSPS)
implementation of quantum cryptographical protocol. We prove that, by utilizing
the Heralded Pair Coherent State (HPCS) photon sources, such a gap can be
actually filled in both BB84 and SARG quantum key distribution. Thus, a
universal photon source which achieves the up-to-date optimal key rate for each
transmission distance is obtained.


title: Accretion and destruction of planetesimals in turbulent disks

abstract:
  We study the conditions for collisions between planetesimals to be
accretional or disruptive in turbulent disks, through analytical arguments
based on fluid dynamical simulations and orbital integrations. In turbulent
disks, the velocity dispersion of planetesimals is pumped up by random
gravitational perturbations from density fluctuations of the disk gas. When the
velocity dispersion is larger than the planetesimals' surface escape velocity,
collisions between planetesimals do not result in accretion, and may even lead
to their destruction. In disks with a surface density equal to that of the
``minimum mass solar nebula'' and with nominal MRI turbulence, we find that
accretion proceeds only for planetesimals with sizes above $\sim 300$ km at 1AU
and $\sim 1000$ km at 5AU. We find that accretion is facilitated in disks with
smaller masses. However, at 5AU and for nominal turbulence strength, km-sized
planetesimals are in a highly erosive regime even for a disk mass as small as a
fraction of the mass of Jupiter. The existence of giant planets implies that
either turbulence was weaker than calculated by standard MRI models or some
mechanism was capable of producing Ceres-mass planetesimals in very short
timescales. In any case, our results show that in the presence of turbulence
planetesimal accretion is most difficult in massive disks and at large orbital
distances.


title:
Genetic code evolution as an initial driving force for molecular
  evolution

abstract:
  There is an intrinsic relationship between the molecular evolution in
primordial period and the properties of genomes and proteomes of contemporary
species. The genomic data may help us understand the driving force of evolution
of life at molecular level. In absence of evidence, numerous problems in
molecular evolution had to fall into a twilight zone of speculation and
controversy in the past. Here we show that delicate structures of variations of
genomic base compositions and amino acid frequencies resulted from the genetic
code evolution. And the driving force of evolution of life also originated in
the genetic code evolution. The theoretical results on the variations of amino
acid frequencies and genomic base compositions agree with the experimental
observations very well, not only in the variation trends but also in some fine
structures. Inversely, the genomic data of contemporary species can help
reconstruct the genetic code chronology and amino acid chronology in primordial
period. Our results may shed light on the intrinsic mechanism of molecular
evolution and the genetic code evolution.


title:
High Spatial Resolution Mid-IR Imaging of V838 Monocerotis: Evidence of
  New Circumstellar Dust Creation

abstract:
  We report high spatial resolution 11.2 and 18.1 micron imaging of V838
Monocerotis obtained with Gemini Observatory's Michelle instrument in 2007
March. Strong emission is observed from the unresolved stellar core of V838 Mon
in our Gemini imagery, and is confirmed by Spitzer MIPS 24 micron imaging
obtained in 2007 April. The 2007 flux density of the unresolved mid-infrared
emission component is 2 times brighter than that observed in 2004. No clear
change in the net amount of 24 micron extended emission is observed between the
2004 and 2007 epoch Spitzer imagery. We interpret these data as evidence that
V838 Mon has experienced a new circumstellar dust creation event. We suggest
that this newly created dust has condensed from the expanding ejecta produced
from V838 Mon's 2002 outburst events, and is most likely clumpy. We speculate
that one (or more) of these clumps might have passed through the line-of-sight
in late 2006, producing the brief multi-wavelength photometric event reported
by Bond (2006) and Munari et al (2007). We detect no evidence of extended
emission above a level of 1 mJy at 11.2 microns and 7 mJy at 18.1 microns over
radial distances of 1860 - 93000 AU (0.3-15.0 arcsec) from the central source.
Using the simple assumption that ejecta material expands at a constant velocity
of 300-500 km/s, this gap of thermal emission suggests that no significant
prior circumstellar dust production events have occurred within the past
900-1500 years.


title: Reentrant phase transition in a predator-prey model

abstract:
  We numerically investigate the six-species predator-prey game in complex
networks as well as in $d$-dimensional hypercubic lattices with $d=1,2,..., 6$.
The interaction topology of the six species contains two loops, each of which
is composed of cyclically predating three species. As the mutation rate $P$ is
lowered below the well-defined phase transition point, the $Z_2$ symmetry
related with the interchange of the two loops is spontaneously broken, and it
has been known that the system develops the defensive alliance in which three
cyclically predating species defend each other against the invasion of other
species. In the small-world network structure characterized by the rewiring
probability $\alpha$, the phase diagram shows the reentrant behavior as
$\alpha$ is varied, indicating a twofold role of the shortcuts. In
$d$-dimensional regular hypercubic lattices, the system also exhibits the
reentrant phase transition as $d$ is increased. We identify universality class
of the phase transition and discuss the proper mean-field limit of the system.


title:
Archer: A Community Distributed Computing Infrastructure for Computer
  Architecture Research and Education

abstract:
  This paper introduces Archer, a community-based computing resource for
computer architecture research and education. The Archer infrastructure
integrates virtualization and batch scheduling middleware to deliver
high-throughput computing resources aggregated from resources distributed
across wide-area networks and owned by different participating entities in a
seamless manner. The paper discusses the motivations leading to the design of
Archer, describes its core middleware components, and presents an analysis of
the functionality and performance of a prototype wide-area deployment running a
representative computer architecture simulation workload.


title:
The HD 163296 Circumstellar Disk in Scattered Light: Evidence of
  Time-Variable Self-Shadowing

abstract:
  We present the first multi-color view of the scattered light disk of the
Herbig Ae star HD 163296, based on coronagraphic observations from the Hubble
Space Telescope Advanced Camera for Surveys (ACS). Radial profile fits of the
surface brightness along the disk's semi-major axis indicates that the disk is
not continuously flared, and extends to 540 AU. The disk's color (V-I)=1.1 at a
radial distance of 3.5 arcseconds is redder than the observed stellar color
(V-I)=0.15. This red disk color might be indicative of either an evolution in
the grain size distribution (i.e. grain growth) and/or composition, both of
which would be consistent with the observed non-flared geometry of the outer
disk. We also identify a single ansa morphological structure in our F435W ACS
data, which is absent from earlier epoch F606W and F814W ACS data, but
corresponds to one of the two ansa observed in archival HST STIS coronagraphic
data.
  Following transformation to similar band-passes, we find that the scattered
light disk of HD 163296 is 1 mag arcsec$^{-2}$ fainter at 3.5 arcseconds in the
STIS data than in the ACS data. Moreover, variations are seen in (i) the
visibility of the ansa(e) structures, in (ii) the relative surface brightness
of the ansa(e) structures, and in (iii) the (known) intrinsic polarization of
the system. These results indicate that the scattered light from the HD 163296
disk is variable. We speculate that the inner disk wall, which Sitko et al.
suggests has a variable scale height as diagnosed by near-IR SED variability,
induces variable self-shadowing of the outer disk. We further speculate that
the observed surface brightness variability of the ansa(e) structures may
indicate that the inner disk wall is azimuthally asymmetric.


title: Unravelling Lorentz Covariance and the Spacetime Formalism

abstract:
  We report the discovery of an exact mapping from Galilean time and space
coordinates to Minkowski spacetime coordinates, showing that Lorentz covariance
and the spacetime construct are consistent with the existence of a dynamical
3-space, and "absolute motion". We illustrate this mapping first with the
standard theory of sound, as vibrations of a medium, which itself may be
undergoing fluid motion, and which is covariant under Galilean coordinate
transformations. By introducing a different non-physical class of space and
time coordinates it may be cast into a form that is covariant under "Lorentz
transformations" wherein the speed of sound is now the "invariant speed". If
this latter formalism were taken as fundamental and complete we would be lead
to the introduction of a pseudo-Riemannian "spacetime" description of sound,
with a metric characterised by an "invariant speed of sound". This analysis is
an allegory for the development of 20th century physics, but where the Lorentz
covariant Maxwell equations were constructed first, and the Galilean form was
later constructed by Hertz, but ignored. It is shown that the Lorentz
covariance of the Maxwell equations only occurs because of the use of
non-physical space and time coordinates. The use of this class of coordinates
has confounded 20th century physics, and resulted in the existence of a
"flowing" dynamical 3-space being overlooked. The discovery of the dynamics of
this 3-space has lead to the derivation of an extended gravity theory as a
quantum effect, and confirmed by numerous experiments and observations.


title: Revisiting the Perfect Lens

abstract:
  We carefully examine the negative refractive index slab perfect lens theory
by Pendry and point out an inconsistency that can be resolved. As a result, we
find negative index slabs do not amplify or enhance evanescent waves and
therefore they do not make a perfect lens in the sense that was originally
suggested.


title: Correcting stellar oscillation frequencies for near-surface effects

abstract:
  In helioseismology, there is a well-known offset between observed and
computed oscillation frequencies. This offset is known to arise from improper
modeling of the near-surface layers of the Sun, and a similar effect must occur
for models of other stars. Such an effect impedes progress in asteroseismology,
which involves comparing observed oscillation frequencies with those calculated
from theoretical models. Here, we use data for the Sun to derive an empirical
correction for the near-surface offset, which we then apply three other stars
(alpha Cen A, alpha Cen B and beta Hyi). The method appears to give good
results, in particular providing an accurate estimate of the mean density of
each star.


title: Measuring primordial non-gaussianity without cosmic variance

abstract:
  Non-gaussianity in the initial conditions of the universe is one of the most
powerful mechanisms to discriminate among the competing theories of the early
universe. Measurements using bispectrum of cosmic microwave background
anisotropies are limited by the cosmic variance, i.e. available number of
modes. Recent work has emphasized the possibility to probe non-gaussianity of
local type using the scale dependence of large scale bias from highly biased
tracers of large scale structure. However, this power spectrum method is also
limited by cosmic variance, finite number of structures on the largest scales,
and by the partial degeneracy with other cosmological parameters that can mimic
the same effect. Here we propose an alternative method that solves both of
these problems. It is based on the idea that on large scales halos are biased,
but not stochastic, tracers of dark matter: by correlating a highly biased
tracer of large scale structure against an unbiased tracer one eliminates the
cosmic variance error, which can lead to a high signal to noise even from the
structures comparable to the size of the survey. The square of error
improvement on non-gaussianity parameter f_nl relative to the power spectrum
method scales as Pn/2, where P and n is the power spectrum and the number
density of the biased tracer, respectively. For an ideal survey out to z=2 the
error reduction can be as large as a factor of seven, which should guarantee a
detection of non-gaussianity from an all sky survey of this type. The
improvements could be even larger if high density tracers that are sensitive to
non-gaussianity can be identified and measured over a large volume.


title:
Random matrix theory and the evolution of business cycle synchronisation
  1886-2006

abstract:
  The major study by Bordo and Helbing (2003) analyses the business cycle in
Western economies 1881-2001. They examine four distinct periods in economic
history, and conclude that there is a secular trend towards greater
synchronisation for much of the 20th century. Their analysis, in common with
the standard economic literature on business cycle synchronisation, relies upon
the estimation of an empirical correlation matrix of time series data of
macroeconomic aggregates. However because of the small number of observations
and economies, the empirical correlation matrix may contain considerable noise.
Random matrix theory was developed to overcome this problem. I use random
matrix theory, and the associated technique of agglomerative hierarchical
clustering, to examine the evolution of business cycle synchronisation between
the capitalist economies in the long-run. Contrary to the findings of Bordo and
Helbing, it is not possible to speak of a 'secular trend' towards greater
synchronisation over the period as a whole. During the pre-First World War
period, the cross-country correlations of annual real GDP growth are
indistinguishable from those which could be generated by a purely random
matrix. The periods 1920-38 and 1948-72 do show a certain degree of
synchronisation, but it is very weak. In particular, the cycles of the major
economies cannot be said to be synchronised. Such synchronisation as exists in
the overall data is due to meaningful co-movements in sub-groups. So the degree
of synchronisation has evolved fitfully. It is only in the most recent
1973-2006 period that we can speak meaningfully of anything resembling an
international business cycle.


title: Measurements of gamma/phi_3 at B factories

abstract:
  This report summarizes the most recent progress in measuring the angle gamma
(or phi_3) of the Unitarity Triangle.


title:
Spatial Interference Cancellation for Multi-Antenna Mobile Ad Hoc
  Networks

abstract:
  Interference between nodes is a critical impairment in mobile ad hoc networks
(MANETs). This paper studies the role of multiple antennas in mitigating such
interference. Specifically, a network is studied in which receivers apply
zero-forcing beamforming to cancel the strongest interferers. Assuming a
network with Poisson distributed transmitters and independent Rayleigh fading
channels, the transmission capacity is derived, which gives the maximum number
of successful transmissions per unit area. Mathematical tools from stochastic
geometry are applied to obtain the asymptotic transmission capacity scaling and
characterize the impact of inaccurate channel state information (CSI). It is
shown that, if each node cancels L interferers, the transmission capacity
decreases as the outage probability to the power of 1/(L+1) as the outage
probability vanishes. For fixed outage probability, as L grows, the
transmission capacity increases as L to the power of (1-2/alpha) where alpha is
the path-loss exponent. Moreover, CSI inaccuracy is shown to have no effect on
the transmission capacity scaling as the outage probability vanishes, provided
that the CSI training sequence has an appropriate length, which we derived.
Numerical results suggest that canceling merely one interferer by each node
increases the transmission capacity by an order of magnitude or more, even when
the CSI is imperfect.


title: 3D Electron Fluid Turbulence at Nanoscales in Dense Plasmas

abstract:
  We have performed three dimensional nonlinear fluid simulations of electron
fluid turbulence at nanoscales in an unmagnetized warm dense plasma in which
mode coupling between wave function and electrostatic potential associated with
underlying electron plasma oscillations (EPOs) lead to nonlinear cascades in
inertial range. While the wave function cascades towards smaller length scales,
electrostatic potential follows an inverse cascade. We find from our
simulations that quantum diffraction effect associated with a Bohm potential
plays a critical role in determining the inertial range turbulent spectrum and
the subsequent transport level exhibited by the 3D EPOs.


title:
Towards Black-Box Accountable Authority IBE with Short Ciphertexts and
  Private Keys

abstract:
  At Crypto'07, Goyal introduced the concept of Accountable Authority
Identity-Based Encryption as a convenient tool to reduce the amount of trust in
authorities in Identity-Based Encryption. In this model, if the Private Key
Generator (PKG) maliciously re-distributes users' decryption keys, it runs the
risk of being caught and prosecuted. Goyal proposed two constructions: the
first one is efficient but can only trace well-formed decryption keys to their
source; the second one allows tracing obfuscated decryption boxes in a model
(called weak black-box model) where cheating authorities have no decryption
oracle. The latter scheme is unfortunately far less efficient in terms of
decryption cost and ciphertext size. In this work, we propose a new
construction that combines the efficiency of Goyal's first proposal with a very
simple weak black-box tracing mechanism. Our scheme is described in the
selective-ID model but readily extends to meet all security properties in the
adaptive-ID sense, which is not known to be true for prior black-box schemes.


title:
Role of Brans-Dicke Theory with or without self-interacting potential in
  cosmic acceleration

abstract:
  In this work we have studied the possibility of obtaining cosmic acceleration
in Brans-Dicke theory with varying or constant $\omega$ (Brans- Dicke
parameter) and with or without self-interacting potential, the background fluid
being barotropic fluid or Generalized Chaplygin Gas. Here we take the power law
form of the scale factor and the scalar field. We show that accelerated
expansion can also be achieved for high values of $\omega$ for closed Universe.


title: Mean-field dynamics of a non-Hermitian Bose-Hubbard dimer

abstract:
  We investigate an $N$-particle Bose-Hubbard dimer with an additional
effective decay term in one of the sites. A mean-field approximation for this
non-Hermitian many-particle system is derived, based on a coherent state
approximation. The resulting nonlinear, non-Hermitian two-level dynamics, in
particular the fixed point structures showing characteristic modifications of
the self-trapping transition, are analyzed. The mean-field dynamics is found to
be in reasonable agreement with the full many-particle evolution.


title: Breakdown of half-metallic ferromagnetism in zinc-blende II-V compounds

abstract:
  We investigated the electronic and magnetic properties of a series of
zinc-blend II-V compounds by carrying out density-functional-theory
calculations including spin-orbit couplings. Contrary to the case of CaN and
CaP, the half-metallic characteristics of the II-V compounds such as CaSb and
CaBi were found to be destroyed. Our analysis of the valence band structures of
CaAs, CaSb, and CaBi revealed a critical role of the spin-orbit coupling
interactions on the exchange-split band structure, thereby leading to breakdown
of the half-metallic ferromagnetism for the systems with heavier group V
elements in the zinc-blend II-V compounds.


title:
Effects of out-of-plane disorder on the nodal quasiparticle and
  superconducting gap in single-layer Bi$_2$Sr$_{1.6}Ln_{0.4}$CuO$_{6+\delta}$
  ($Ln$ = La, Nd, Gd)

abstract:
  How out-of-plane disorder affects the electronic structure has been
investigated for the single-layer cuprates
Bi$_2$Sr$_{1.6}$$Ln$$_{0.4}$CuO$_{6+\delta}$ ($Ln$ = La, Nd, Gd) by
angle-resolved photoemission spectroscopy. We have observed that, with
increasing disorder, while the Fermi surface shape and band dispersions are not
affected, the quasi-particle width increases, the anti-nodal gap is enhanced
and the superconducting gap in the nodal region is depressed. The results
indicate that the superconductivity is significantly depressed by out-of-plane
disorder through the enhancement of the anti-nodal gap and the depression of
the superconducting gap in the nodal region.


title:
Three-orbital Kondo effect in single quantum dot system with plural
  electrons

abstract:
  We study the Kondo effect and related transport properties in orbitally
degenerate vertical quantum dot systems with plural electrons. Applying the
non-crossing approximation to the three-orbital Anderson impurity model with
the finite Coulomb interaction and Hund-coupling, we investigate the
magnetic-field dependence of the conductance and thermopower. We also introduce
an additional orbital splitting to take account of the realistic many-body
effect in the vertical quantum dot system. It is clarified how the
three-orbital Kondo effect influences the transport properties via the
modulation of the Kondo temperature and unitary limit of transport quantities
due to the change of the symmetry in the system.


title: An alternative quantum fidelity for mixed states of qudits

abstract:
  We give an alternative definition of quantum fidelity for two density
operators on qudits in terms of the Hilbert-Schmidt inner product between them
and their purity. It can be regarded as the well-defined operator fidelity for
the two operators and satisfies all Jozsa's four axioms up to a normalization
factor. One desire property is that it is not computationally demanding.


title:
Probing the spin polarization of current by soft X-ray imaging of
  current-induced magnetic vortex dynamics

abstract:
  Time-resolved soft X-ray transmission microscopy is applied to image the
current-induced resonant dynamics of the magnetic vortex core realized in a
micronsized Permalloy disk. The high spatial resolution better than 25 nm
enables us to observe the resonant motion of the vortex core. The result also
provides the spin polarization of the current to be 0.67 +/-0.16 for Permalloy
by fitting the experimental results with an analytical model in the framework
of the spin-transfer torque.


title: A Hertzian Plasmonic Nanodimer as an Efficient Optical Nanoantenna

abstract:
  Inspired by the geometry and shape of the classical radio-frequency radiator,
the Hertzian dipole, here we analyze the design of a plasmonic optical dimer
nanoantenna. We show how it may be possible to operate a pair of closely spaced
spherical nanoparticles as an efficient optical nanoradiator, and how its
tuning and matching properties may be tailored with great degree of freedom by
designing suitable nanoloads placed at the dimer's gap. In this sense, we
successfully apply nanocircuit concepts to model the loading nanoparticles.
High levels of optical radiation efficiency are achieved, even considering the
realistic absorption of optical metals, thanks to this specific geometry and
design.


title: Calabi-Yau components in general type hypersurfaces

abstract:
  For a one-parameter family of general type hypersurfaces with bases of
holomorphic n-forms, we construct open covers using tropical geometry. We show
that after normalization, each holomorphic n-form is approximately supported on
a unique open component and such a pair approximates a Calabi-Yau hypersurface
together with its holomorphic n-form as the parameter becomes large. We also
show that the Lagrangian fibers in the fibration constructed by Mikhalkin are
asymptotically special Lagrangian. As the holomorphic n-form plays an important
role in mirror symmetry for Calabi-Yau manifolds, our results is a step toward
understanding mirror symmetry for general type manifolds.


title: N=4 Superconformal Mechanics and Black Holes

abstract:
  The motion of a particle near the Reissner-Nordstrom black hole horizon is
described by conformal mechanics. In this paper we present an extended
one-dimensional analysis of the N=4 superconformal mechanics coupled to n
copies of N=8, d=1 vector supermultiplets. The constructed system possesses a
special Kahler geometry in the scalar sector of the vector multiplets as well
as an N=4 superconformal symmetry which is provided by a proper coupling to a
dilaton superfield. The superconformal symmetry completely fixes the resulting
action. We explicitly demonstrate that the electric and magnetic charges,
presenting in the "effective black hole" action, appear as a result of
resolving constraints on the auxiliary components of the vector
supermultiplets. We present the component action, supercharges and Hamiltonian
with all fermionic terms included. One of the possible ways to generalize the
black hole potential is to consider a modified version of the N=4
superconformal multiplet where its auxiliary components acquire non-zero
constant values. We explicitly write down the corresponding modified black hole
potential.


title:
The jet of Markarian 501 from millions of Schwarzschild radii down to a
  few hundreds

abstract:
  Aims: The TeV BL Lac object Markarian 501 is a complex, core dominated radio
source, with a one sided, twisting jet on parsec scales. In the present work,
we attempt to extend our understanding of the source physics to regions of the
radio jet which have not been accessed before.
  Methods: We present new observations of Mrk 501 at 1.4 and 86 GHz. The 1.4
GHz data were obtained using the Very Large Array (VLA) and High Sensitivity
Array (HSA) in November 2004, in full polarization, with a final r.m.s. noise
of 25 microJy/beam in the HSA total intensity image; the 86 GHz observations
were performed in October 2005 with the Global Millimeter VLBI Array (GMVA),
providing an angular resolution as good as 110 x 40 microarcseconds.
  Results: The sensitivity and resolution provided by the HSA make it possible
to detect the jet up to ~700 milliarcseconds (corresponding to a projected
linear size of ~500 pc) from its base, while the superior resolution of the 86
GHz GMVA observations probes the innermost regions of the jet down to ~200
Schwarzschild radii. The brightness temperature at the jet base is in excess of
6e10 K. We find evidence of limb brightening on physical scales from <1 pc to
~40 pc. Polarization images and fits to the trend of jet width and brightness
vs. distance from the core reveal a magnetic field parallel to the jet axis.


title: Broad reprocessed Balmer emission from warped accretion discs

abstract:
  Double peaked broad emission lines in active galactic nuclei are generally
considered to be formed in an accretion disc. In this paper, we compute the
profiles of reprocessing emission lines from a relativistic, warped accretion
disc around a black hole in order to explore the possibility that certain
asymmetries in the double-peaked emission line profile which can not be
explained by a circular Keplerian disc may be induced by disc warping. The disc
warping also provides a solution for the energy budget in the emission line
region because it increases the solid angle of the outer disc portion subtended
to the inner portion of the disc. We adopted a parametrized disc geometry and a
central point-like source of ionizing radiation to capture the main
characteristics of the emission line profile from such discs. We find that the
ratio between the blue and red peaks of the line profiles becoming less than
unity can be naturally predicted by a twisted warped disc, and a third peak can
be produced in some cases. We show that disc warping can reproduce the main
features of multi-peaked line profiles of four active galactic nuclei from the
Sloan Digital Sky Survey.


title:
Selfimprovemvent of the inequality between arithmetic and geometric
  means

abstract:
  We present a refinement, by selfimprovement, of the arithmetic geometric
inequality.


title: Kinetics of water flow through polymer gel

abstract:
  The water flow through the poly(acrylamide) gel under a constant water
pressure is measured by newly designed apparatus. The time evolution of the
water flow in the gel, is calculated based on the collective diffusion model of
the polymer network coupled with the friction between the polymer network and
the water. The friction coefficient are determined from the equilibrium
velocity of water flow. The Young modulus and the Poisson's ratio of the rod
shape gels are measured by the uni-axial elongation experiments, which
determine the longitudinal modulus independently from the water flow
experiments. With the values of the longitudinal modulus and of the friction
determined by the experiments, the calculated results are compared with the
time evolution of the flow experiments. We find that the time evolution of the
water flow is well described by a single characteristic relaxation time
predicted by the collective diffusion model coupled with the water friction.


title: A Jacobson Radical Decomposition of the Fano-Snowflake Configuration

abstract:
  The Fano-Snowflake, a specific $non$-unimodular projective lattice
configuration associated with the smallest ring of ternions $R_{\diamondsuit}$
(arXiv:0803.4436 and 0806.3153), admits an interesting partitioning with
respect to the Jacobson radical of $R_{\diamondsuit}$. The totality of 21 free
cyclic submodules generated by non-unimodular vectors of the free left
$R_{\diamondsuit}$-module $R_{\diamondsuit}^{3}$ are shown to split into three
disjoint sets of cardinalities 9, 9 and 3 according as the number of Jacobson
radical entries in the generating vector is 2, 1 or 0, respectively. The
corresponding "ternion-induced" factorization of the lines of the Fano plane
sitting in the middle of the Fano-Snowflake (6 -- 7 -- 3) is found to $differ
fundamentally$ from the natural one, i. e., from that with respect to the
Jacobson radical of the Galois field of two elements (3 -- 3 -- 1).


title: Magnetism in Graphene Systems

abstract:
  Graphene has attracted a great interest in material science due to its novel
electronic structrues. Recently, magnetism discovered in graphene based systems
opens the possibility of their spintronics application. This paper provides a
comprehensive review on the magnetic behaviors and electronic structures of
graphene systems, including 2-dimensional graphene, 1-dimensional graphene
nanoribbons, and 0-dimensional graphene nanoclusters. Theoretical research
suggests that such metal-free magnetism mainly comes from the localized states
or edges states. By applying external electric field, or by chemical
modification, we can turn the zigzag nanoribbon systems to half metal, thus
obtain a perfect spin filter.


title:
Babel on the Petaplex site: On Rival Calculational methods in SO(10)
  MSGUTs

abstract:
  We compare and contrast the computations that lead to the NMSGUT spectra and
Yukawa couplings that appeared\cite{nmsgut} in 2006 and a recent recalculation
of the same\cite{malinsky}. We argue that an explicit component based method of
computation jeopardizes the power of SO(10) and its sub-groups to organize, in
a unified and automatically phase correlated way, computations of dynamics
beyond the basic mass matrix computation. The correct (one line) prescription
for generating MSSM Yukawas from SO(10) ones was given in \cite{ag2} and
requires no computation beyond the identification of null vectors of the Higgs
doublet mass matrix and the Clebsches given in \cite{ag1,ag2}. It was already
used to derive all fermion Yukawas and Majorana masses in \cite{ag2,nmsgut}. We
thus urge the adoption of a uniform notation and methodology based on descent
from SO(10) to the SM through the Pati-Salam maximal subgroup of SO(10) to
avoid Babel in this rapidly developing and highly promising subject.


title: On Entanglement and Separability

abstract:
  We present a new necessary and sufficient condition to determine the
entanglement status of an arbitrary N-qubit quantum state (maybe pure or mixed)
represented by a density matrix. A necessary condition satisfied by separable
bipartite quantum states was obtained by A. Peres, [1]. A. Peres showed that if
a bipartite state represented by the density matrix is separable then its
partial transpose is positive semidefinite and has no negative eigenvalues. In
other words, if the partial transpose is not positive semidefinite and so one
or more of its eigenvalues are negative then the state represented by the
corresponding density matrix is entangled. It was then shown by M. Horodecki
et.al, [2], that this necessary condition is also sufficient for two-by-two and
two-by-three dimensional systems. However, in other dimensions, it was shown by
P. Horodecki, [3], that the criterion due to A. Peres is not sufficient. In
this paper, we develop a new approach and a new criterion for deciding the
entanglement status of the states represented by the density matrices
corresponding to N-qubit systems. We begin with a 2-qubit case and then show
that these results for 2-qubit systems can be extended to N-qubit systems by
proceeding along similar lines. We discuss few examples to illustrate the
method proposed in this paper for testing the entanglement status of few
density matrices.


title:
Cloudy Atmosphere of the Extra-solar Planet HD189733b : A Possible
  Explanation of the Detected B-band Polarization

abstract:
  The peak amplitude of linear polarization detected recently from an
extrasolar hot giant planet HD 189733b, is a few times of $10^{-4}$, more than
an order of magnitude higher than all theoretical predictions. Rayleigh
scattering off $H_2$ and $He$ may although give rise to a planet-star flux
ratio of the order of $10^{-4}$ in the blue band, it cannot account for the
high polarization unless the planet has an unusually extended atmosphere.
Therefore, it is suggested that the high polarization should be attributed to
the presence of a thin cloud of sub-micron size dust grains in the upper
visible atmosphere which supports the observational finding of an almost
feature-less transmission spectrum in the optical with no indication of the
expected alkaline absorption features. It is found that the polarimetry
observation allows for a small eccentricity of the orbit that is predicted from
the time delay of the secondary eclipse of the planet. The estimated longitude
of the ascending node is $16^o\pm6$ which interestingly coincides with the
observationally inferred location of the peak hemisphere-integrated brightness.


title:
A Lorentz invariant formulation of the Yang-Mills theory with gauge
  invariant ghost field Lagrangian

abstract:
  A new formulation of the Yang-Mills theory which allows a manifestly
covariant gauge fixing accompanied by a gauge invariant ghost field interaction
is proposed. The gauge condition selects a unique representative in the class
of gauge equivalent configurations.


title: Wavelet analysis of a large sample of AGN at high radio frequencies

abstract:
  We have studied the characteristic timescales of 80 AGNs at 22, 37 and 90 GHz
examining the properties of the wavelet method and comparing them to
traditional Fourier-based methods commonly used in astronomy. We used the
continuous wavelet transform with the Morlet wavelet to study the
characteristic timescales. We also gain information when the timescale is
present in the flux curve and if it is persistent or not. Our results show that
the sources are not periodic and changes in the timescales over a long time are
common. The property of wavelets to be able to distinguish when the timescale
has been present is superior to the Fourier-based methods. Therefore we
consider it appropriate to use wavelets when the quasi-periodicities in AGNs
are studied.


title: Viscous Modified Gravity on a RS Brane Embedded in AdS5

abstract:
  We consider a modified gravity fluid on a Randall-Sundrum II brane situated
at y=0, the action containing a power \alpha of the scalar curvature. As is
known from 4D spatially flat modified gravity, the presence of a bulk viscosity
may drive the cosmic fluid into the phantom region (w < -1) and thereafter
inevitably into the Big Rip singularity, even it is initially nonviscous and
lies in the quintessence region (w > -1). The condition for this to occur is
that the bulk viscosity contains the power (2\alpha-1) of the scalar expansion.
We combine this with the 5D RS II model, and find that the Big Rip, occurring
for \alpha > 1/2, carries over to the metric for the bulk metric, |y|>0.
Actually, the scale factors on the brane and in the bulk become simply
proportional to each other.


title:
Two-Site shift Product Wave Function Renormalization Group Method
  Applied to Quantum Systems

abstract:
  We report a way of wave function estimation for the density matrix
renormalization group (DMRG) method applied to quantum systems, which has
2-site modulation, when the system size extension is necessary in both the
finite and the infinite algorithms. The estimation is performed by
renormalization group (RG) transformation applied to the ground state wave
function, which is represented as the matrix product. This RG scheme is known
as the product wave function renormalization group (PWFRG) method. In order to
treat the 2-site modulation, the operation of the RG transformation is shifted
by amount of 2 lattice sites. It turns out that this 2-site shift algorithm
provides better wave function estimation in the thermodynamic limit, compared
with the previously known PWFRG algorithm.


title:
Entanglement swapping between electromagnetic field modes and matter
  qubits

abstract:
  Scalable quantum networks require the capability to create, store and
distribute entanglement among distant nodes (atoms, trapped ions, charge and
spin qubits built on quantum dots, etc.) by means of photonic channels. We show
how the entanglement between qubits and electromagnetic field modes allows
generation of entangled states of remotely located qubits. We present
analytical calculations of linear entropy and the density matrix for the
entangled qubits for the system described by the Jaynes-Cummings model. We also
discuss the influence of decoherence. The presented scheme is able to drive an
initially separable state of two qubits into an highly entangled state suitable
for quantum information processing.


title: A class of Sasakian 5-manifolds

abstract:
  We obtain some general results on Sasakian Lie algebras and prove as a
consequence that a (2n + 1)-dimensional nilpotent Lie group admitting
left-invariant Sasakian structures is isomorphic to the real Heisenberg group
$H_{2n + 1}$. Furthermore, we classify Sasakian Lie algebras of dimension 5 and
determine which of them carry a Sasakian $\alpha$-Einstein structure. We show
that a 5-dimensional solvable Lie group with a left-invariant Sasakian
structure and which admits a compact quotient by a discrete subgroup is
isomorphic to either $H_5$ or a semidirect product $\R \ltimes (H_3 \times
\R)$. In particular, the compact quotient is an $S^1$-bundle over a
4-dimensional K\"ahler solvmanifold.


title: Hook lengths and shifted parts of partitions

abstract:
  Some conjectures on partition hook lengths, recently stated by the author,
have been proved and generalized by Stanley, who also needed a formula by
Andrews, Goulden and Jackson on symmetric functions to complete his derivation.
Another identity on symmetric functions can be used instead. The purpose of
this note is to prove it.


title: Fractional Quantum Hall State in Coupled Cavities

abstract:
  We propose a scheme to realize the fractional quantum Hall system with atoms
confined in a two-dimensional array of coupled cavities. Our scheme is based on
simple optical manipulation of atomic internal states and inter-cavity hopping
of virtually excited photons. It is shown that as well as the fractional
quantum Hall system, any system of hard-core bosons on a lattice in the
presence of an arbitrary Abelian vector potential can be simulated solely by
controlling the phases of constantly applied lasers. The scheme, for the first
time, exploits the core advantage of coupled cavity simulations, namely the
individual addressability of the components and also brings the gauge potential
into such simulations as well as the simple optical creation of particles.


title: Consistency Principle in Biological Dynamical Systems

abstract:
  We propose a principle of consistency between different hierarchical levels
of biological systems. Given a consistency between molecule replication and
cell reproduction, universal statistical laws on cellular chemical abundances
are derived and confirmed experimentally. They include a power law distribution
of gene expressions, a lognormal distribution of cellular chemical abundances
over cells, and embedding of the power law into the network connectivity
distribution. Second, given a consistency between genotype and phenotype, a
general relationship between phenotype fluctuations by genetic variation and
isogenic phenotypic fluctuation by developmental noise is derived. Third, we
discuss the chaos mechanism for stem cell differentiation with autonomous
regulation, resulting from a consistency between cell reproduction and growth
of the cell ensemble.

categories: q-bio.CB cond-mat.stat-mech nlin.AO q-bio.PE q-bio.SC


title: A study of two-qubit density matrices with fermionic purifications

abstract:
  We study 12 parameter families of two qubit density matrices, arising from a
special class of two-fermion systems with four single particle states or
alternatively from a four-qubit state with amplitudes arranged in an
antisymmetric matrix. We calculate the Wooters concurrences and the
negativities in a closed form and study their behavior. We use these results to
show that the relevant entanglement measures satisfy the generalized
Coffman-Kundu-Wootters formula of distributed entanglement. An explicit formula
for the residual tangle is also given. The geometry of such density matrices is
elaborated in some detail. In particular an explicit form for the Bures metric
is given.


title:
Quantitative magnetic information from reciprocal space maps in
  transmission electron microscopy

abstract:
  One of the most challenging issues in the characterization of magnetic
materials is to obtain quantitative analysis on the nanometer scale. Here we
describe how electron magnetic circular dichroism (EMCD) measurements using the
transmission electron microscope (TEM) can be used for that purpose, utilizing
reciprocal space maps. Applying the EMCD sum rules, an orbital to spin moment
ratio of $m_L/m_S=0.08 \pm 0.01$ is obtained for Fe, which is consistent with
the commonly accepted value. Hence, we establish EMCD as a quantitative element
specific technique for magnetic studies, using a widely available instrument
with superior spatial resolution.


title: Determine the spacial term of a two-dimensional heat source

abstract:
  We consider the problem of determining a pair of functions $(u,f)$ satisfying
the heat equation $u_t -\Delta u =\varphi(t)f (x,y)$, where $(x,y)\in
\Omega=(0,1)\times (0,1)$ and the function $\varphi$ is given. The problem is
ill-posed. Under a slight condition on $\varphi$, we show that the solution is
determined uniquely from some boundary data and the initial temperature. Using
the interpolation method and the truncated Fourier series, we construct a
regularized solution of the source term $f$ from non-smooth data. The error
estimate and numerical experiments are given.


title: Relevance of Abelian Symmetry and Stochasticity in Directed Sandpiles

abstract:
  We provide a comprehensive view on the role of Abelian symmetry and
stochasticity in the universality class of directed sandpile models, in context
of the underlying spatial correlations of metastable patterns and scars. It is
argued that the relevance of Abelian symmetry may depend on whether the dynamic
rule is stochastic or deterministic, by means of the interaction of metastable
patterns and avalanche flow. Based on the new scaling relations, we conjecture
critical exponents for avalanche, which is confirmed reasonably well in
large-scale numerical simulations.


title: Surfaces with Parallel Mean Curvature Vector in S^2xS^2 and H^2xH^2

abstract:
  Two holomorphic Hopf differentials for surfaces of non-null parallel mean
curvature vector in S^2xS^2 and H^2xH^2 are constructed. A 1:1 correspondence
between these surfaces and pairs of constant mean curvature surfaces of S^2xR
and H^2xR is established. Using that, surfaces with vanishing Hopf
differentials (in particular spheres with parallel mean curvature vector) are
classified and a rigidity result for constant mean curvature surfaces of S^2xR
and H^2xR is proved.


title: Superconducting density of states and vortex cores of 2H-NbS2

abstract:
  Scanning tunneling microscopy and spectroscopy (STM/S) measurements in the
superconducting dichalcogenide 2H-NbS2 show a peculiar superconducting density
of states with two well defined features at 0.97 meV and 0.53 meV, located
respectively above and below the value for the superconducting gap expected
from single band s-wave BCS model (D=1.76kBTc=0.9 meV). Both features have a
continuous temperature evolution and disappear at Tc = 5.7 K. Moreover, we
observe the hexagonal vortex lattice with radially symmetric vortices and a
well developed localized state at the vortex cores. The sixfold star shape
characteristic of the vortex lattice of the compound 2H-NbSe2 is, together with
the charge density wave order (CDW), absent in 2H-NbS2.


title:
Stochastic 2D hydrodynamical type systems: Well posedness and large
  deviations

abstract:
  We deal with a class of abstract nonlinear stochastic models, which covers
many 2D hydrodynamical models including 2D Navier-Stokes equations, 2D MHD
models and 2D magnetic B\'enard problem and also some shell models of
turbulence. We first prove the existence and uniqueness theorem for the class
considered. Our main result is a Wentzell-Freidlin type large deviation
principle for small multiplicative noise which we prove by weak convergence
method.


title: Relative Chern characters for nilpotent ideals

abstract:
  If I is a nilpotent ideal in a $\mathbb{Q}$-algebra $A$, Goodwillie defined
two isomorphisms from $K_*(A,I)$ to negative cyclic homology, $HN_*(A,I)$. One
is the relative version of the absolute Chern character, and the other is
defined using rational homotopy theory. The question of whether they agree was
implicit in Goodwillie's 1986 Annals paper.
  In this paper, we show that the two isomorphisms agree. Here are three
applications.
  1.Cathelineau proved that the rational homotopy character is compatible with
the $\lambda$-filtration. It follows that the relative Chern character is also
compatible with this filtration for nilpotent ideals.
  2.This agreement, together with Cathelineau's result, was used by the authors
and Haesemeyer to show that the absolute Chern character, from $K(A)$ to
$HN(A)$, is compatible with the $\lambda$-filtration for every commutative
$\mathbb{Q}$-algebra. This is the main result of Infinitesimal cohomology and
the Chern character to negative cyclic homology, arXiv:math/0703133v1.
  3.This agreement can be used to strengthen Ginot's results in "Formules
explicites pour le charactere de Chern en $K$-th\'eorie alg\'ebrique", Ann.
Inst. Fourier 54 (2004).


title: Determine the source term of a two-dimensional heat equation

abstract:
  Let $\Omega$ be a two-dimensional heat conduction body. We consider the
problem of determining the heat source $F(x,t)=\varphi(t)f(x,y)$ with $\varphi$
be given inexactly and $f$ be unknown. The problem is nonlinear and ill-posed.
By a specific form of Fourier transforms, we shall show that the heat source is
determined uniquely by the minimum boundary condition and the temperature
distribution in $\Omega$ at the initial time $t=0$ and at the final time $t=1$.
Using the methods of Tikhonov's regularization and truncated integration, we
construct the regularized solutions. Numerical part is given.


title: A Geometrical Characterization of the Twin Paradox and its Variants

abstract:
  The aim of this paper is to provide a logic-based conceptual analysis of the
twin paradox (TwP) theorem within a first-order logic framework. A geometrical
characterization of TwP and its variants is given. It is shown that TwP is not
logically equivalent to the assumption of the slowing down of moving clocks,
and the lack of TwP is not logically equivalent to the Newtonian assumption of
absolute time. The logical connection between TwP and a symmetry axiom of
special relativity is also studied.


title: Conical defects in growing sheets

abstract:
  A growing or shrinking disc will adopt a conical shape, its intrinsic
geometry characterized by a surplus angle $se$ at the apex. If growth is slow,
the cone will find its equilibrium. Whereas this is trivial if $se <= 0$, the
disc can fold into one of a discrete infinite number of states if $se$ is
positive. We construct these states in the regime where bending dominates,
determine their energies and how stress is distributed in them. For each state
a critical value of $se$ is identified beyond which the cone touches itself.
Before this occurs, all states are stable; the ground state has two-fold
symmetry.


title:
A local hidden-variable model violating Bell's inequalities: a reply to
  Matzkin

abstract:
  Recently, Matzkin claimed the construction of a hidden variable (HV) model
which is both local and equivalent with the quantum-mechanical predictions. In
this paper we will briefly present this HV model and argue, by identifying an
extra non-local "hidden" HV, why this model is not local


title:
Statistical challenges in the analysis of Cosmic Microwave Background
  radiation

abstract:
  An enormous amount of observations on Cosmic Microwave Background radiation
has been collected in the last decade, and much more data are expected in the
near future from planned or operating satellite missions. These datasets are a
goldmine of information for Cosmology and Theoretical Physics; their efficient
exploitation posits several intriguing challenges from the statistical point of
view. In this paper we review a number of open problems in CMB data analysis
and we present applications to observations from the WMAP mission.


title: Exponential bulges and antitruncated disks in lenticular galaxies

abstract:
  The presence of exponential bulges and anti-truncated disks has been noticed
in many lenticular galaxies. In fact, it could be expected because the very
formation of S0 galaxies includes various processes of secular evolution. We
discuss how to distinguish between a pseudobulge and an anti-truncated disk,
and also what particular mechanisms may be responsible for the formation of
anti-truncated disks. Some bright examples of lenticular galaxies with the
multi-tiers exponential stellar structures are presented, among them -- two
central group giant S0s seen face-on and perfectly axisymmetric.


title: Statistical properties of volatility return intervals of Chinese stocks

abstract:
  The statistical properties of the return intervals $\tau_q$ between
successive 1-min volatilities of 30 liquid Chinese stocks exceeding a certain
threshold $q$ are carefully studied. The Kolmogorov-Smirnov (KS) test shows
that 12 stocks exhibit scaling behaviors in the distributions of $\tau_q$ for
different thresholds $q$. Furthermore, the KS test and weighted KS test shows
that the scaled return interval distributions of 6 stocks (out of the 12
stocks) can be nicely fitted by a stretched exponential function
$f(\tau/\bar{\tau})\sim e^{- \alpha (\tau/\bar{\tau})^{\gamma}}$ with
$\gamma\approx0.31$ under the significance level of 5%, where $\bar{\tau}$ is
the mean return interval. The investigation of the conditional probability
distribution $P_q(\tau | \tau_0)$ and the mean conditional return interval
$<\tau| \tau_0>$ demonstrates the existence of short-term correlation between
successive return interval intervals. We further study the mean return interval
$<\tau| \tau_0>$ after a cluster of $n$ intervals and the fluctuation $F(l)$
using detrended fluctuation analysis and find that long-term memory also exists
in the volatility return intervals.


title: The exact radiation-reaction equation for a classical charged particle

abstract:
  An unsolved problem of classical mechanics and classical electrodynamics is
the search of the exact relativistic equations of motion for a classical
charged point-particle subject to the force produced by the action of its EM
self-field. The problem is related to the conjecture that for a classical
charged point-particle there should exist a relativistic equation of motion (RR
equation) which results both non-perturbative, in the sense that it does not
rely on a perturbative expansion on the electromagnetic field generated by the
charged particle and non-asymptotic, i.e., it does not depend on any
infinitesimal parameter. In this paper we intend to propose a novel solution to
this well known problem, and in particular to point out that the RR equation is
necessarily variational. The approach is based on two key elements: 1) the
adoption of the relativistic hybrid synchronous Hamilton variational principle
recently pointed out (Tessarotto et al, 2006). Its basic feature is that it can
be expressed in principle in terms of arbitrary "hybrid" variables (i.e.,
generally non-Lagrangian and non-Hamiltonian variables); 2) the variational
treatment of the EM self-field, taking into account the exact particle
dynamics.


title: BRST charges for finite nonlinear algebras

abstract:
  Some ingredients of the BRST construction for quantum Lie algebras are
applied to a wider class of quadratic algebras of constraints. We build the
BRST charge for a quantum Lie algebra with three generators and
ghost-anti-ghosts commuting with constraints. We consider a one-parametric
family of quadratic algebras with three generators and show that the BRST
charge acquires the conventional form after a redefinition of ghosts. The
modified ghosts form a quadratic algebra. The family possesses a non-linear
involution, which implies the existence of two independent BRST charges for
each algebra in the family. These BRST charges anticommute and form a double
BRST complex.


title: On the topology of untrapped surfaces

abstract:
  Recently a simple proof of the generalizations of Hawking's black hole
topology theorem and its application to topological black holes for higher
dimensional ($n\geq 4$) spacetimes was given \cite{rnew}. By applying the
associated new line of argument it is proven here that strictly stable
untrapped surfaces do possess exactly the same topological properties as
strictly stable marginally outer trapped surfaces (MOTSs) are known to have. In
addition, a quasi-local notion of outwards and inwards pointing spacelike
directions--applicable to untrapped and marginally trapped surfaces--is also
introduced.


title: Exclusive charm production in pbar p collisions at s^1/2 <15 GeV

abstract:
  We discuss the open charm production in peripheral reactions
  $\bar pp\to \bar Y_cY_c$ and $\bar pp\to M_c\bar M_c$, where
  $Y_c$ and $M_c$ stand for $\Lambda_c^+,\Sigma_c^+$ and
  $D,D^*$, respectively, at $\sqrt{s}\lesssim 15$ GeV, which corresponds to the
energy range of FAIR. Our consideration is based on the topological
decomposition of the planar quark and diquark diagrams which allows to estimate
consistently meson and baryon exchange trajectories and energy scale parameters
as well. The spin dependence is determined by the effective interaction of
lowest exchanged resonance. Unknown parameters are fixed by an independent
analysis of open strangeness production in $\bar pp\to \bar YY$ and $\bar pp\to
\bar KK$ reactions and of SU(4) symmetry. We present the corresponding cross
sections and longitudinal double-spin asymmetries for exclusive binary
reactions with open charm mesons and baryons in the final state. The
polarization observables have a non-trivial $t$ and $s$ dependence which is
sensitive to details of the open charm production mechanism.


title: Cooperation Evolution in Random Multiplicative Environments

abstract:
  Most real life systems have a random component: the multitude of endogenous
and exogenous factors influencing them result in stochastic fluctuations of the
parameters determining their dynamics. These empirical systems are in many
cases subject to noise of multiplicative nature. The special properties of
multiplicative noise as opposed to additive noise have been noticed for a long
while. Even though apparently and formally the difference between free additive
vs. multiplicative random walks consists in just a move from normal to
log-normal distributions, in practice the implications are much more far
reaching. While in an additive context the emergence and survival of
cooperation requires special conditions (especially some level of reward,
punishment, reciprocity), we find that in the multiplicative random context the
emergence of cooperation is much more natural and effective. We study the
various implications of this observation and its applications in various
contexts.


title:
On paraquaternionic submersions between paraquaternionic K\"ahler
  manifolds

abstract:
  In this paper we deal with some properties of a class of semi-Riemannian
submersions between manifolds endowed with paraquaternionic structures, proving
a result of non-existence of paraquaternionic submersions between
paraquaternionic K\"ahler non locally hyper paraK\"ahler manifolds. Then we
examine, as an example, the canonical projection of the tangent bundle, endowed
with the Sasaki metric, of an almost paraquaternionic Hermitian manifold.


title: The best constant in a fractional Hardy inequality

abstract:
  We prove an optimal Hardy inequality for the fractional Laplacian on the
half-space.


title: Factorization structures with a 2-dimensional factor

abstract:
  We introduce the notion of quantum duplicates of an (associative, unital)
algebra, motivated by the problem of constructing toy-models for quantizations
of certain configuration spaces in quantum mechanics. The proposed (algebraic)
model relies on the classification of factorization structures with a
two-dimensional factor. In the present paper, main properties of this
particular kind of structures are determined, and we present a complete
description of quantum duplicates of finite set algebras. As an application, we
obtain a classification (up to isomorphism) of all the algebras of dimension 4
(over an arbitrary field) that can be factorized as a product of two factors.


title: Hamiltonian degree sequences in digraphs

abstract:
  We show that for each \eta>0 every digraph G of sufficiently large order n is
Hamiltonian if its out- and indegree sequences d^+_1\le ... \le d^+_n and d^-
_1 \le ... \le d^-_n satisfy
  (i) d^+_i \geq i+ \eta n or d^-_{n-i- \eta n} \geq n-i and
  (ii) d^-_i \geq i+ \eta n or d^+_{n-i- \eta n} \geq n-i for all i < n/2.
  This gives an approximate solution to a problem of Nash-Williams concerning a
digraph analogue of Chv\'atal's theorem. In fact, we prove the stronger result
that such digraphs G are pancyclic.


title: PT-symmetric extensions of the supersymmetric Korteweg-de Vries equation

abstract:
  We discuss several PT-symmetric deformations of superderivatives. Based on
these various possibilities, we propose new families of complex PT-symmetric
deformations of the supersymmetric Korteweg-de Vries equation. Some of these
new models are mere fermionic extensions of the former in the sense that they
are formulated in terms of superspace valued superfields containing bosonic and
fermionic fields, breaking however the supersymmetry invariance. Nonetheless,
we also find extensions, which may be viewed as new supersymmetric Korteweg-de
Vries equation. Moreover, we show that these deformations allow for a
non-Hermitian Hamiltonian formulation and construct three charges associated to
the corresponding flow.


title:
Alg\`ebres et cog\`ebres de Gerstenhaber et cohomologie de
  Chevalley-Harrison

abstract:
  The fundamental example of Gerstenhaber algebra is the space
$T_{poly}({\mathbb R}^d)$ of polyvector fields on $\mathbb{R}^d$, equipped with
the wedge product and the Schouten bracket. In this paper, we explicitely
describe what is the enveloping $G_\infty$ algebra of a Gerstenhaber algebra
$\mathcal{G}$. This structure gives us a definition of the Chevalley-Harrison
cohomology operator for $\mathcal{G}$. We finally show the nontriviality of a
Chevalley-Harrison cohomology group for a natural Gerstenhaber subalgebra in
$T_{poly}({\mathbb R}^d)$.


title:
A rooted-trees q-series lifting a one-parameter family of Lie
  idempotents

abstract:
  We define and study a series indexed by rooted trees and with coefficients in
Q(q). We show that it is related to a family of Lie idempotents. We prove that
this series is a q-deformation of a more classical series and that some of its
coefficients are Carlitz q-Bernoulli numbers.


title: The evolution of EU business cycle synchronisation 1981-2007

abstract:
  Most of the analytical techniques used in the business cycle synchronisation
literature rely upon the estimation of an empirical correlation matrix of time
series data of macroeconomic aggregates, real GDP usually being the key
variable. But the small number of available observations and small number of
economies mean that the empirical correlation matrix may contain considerable
noise. Random matrix theory was developed in physics to overcome this problem.
The largest eigenvalue of the correlation matrix informs us directly about the
degree to which movements of the economies are genuinely correlated. The
evolution of business cycle synchronisation can be analysed with the temporal
evolution of the largest eigenvalue over a fixed window of data. I analyse
quarterly real GDP data 1981Q1-2008Q1 for the core EU economies - Germany,
France, Italy, Spain, Netherlands, Belgium - along with the UK, which is a
member of the EU but not the Euro, and the US as a comparator. The core EU
economies have shown varying but strong synchronisation over the whole period.
In contrast, the UK and the US are much more synchronised with each other than
they are with the core EU economies.


title: String-Inspired Chern-Simons Modified Gravity In 4-Dimensions

abstract:
  Chern-Simons modified gravity models in 4-dimensions are shown to be special
cases of low energy effective string models to first order in the string
constant.


title: The art of community detection

abstract:
  Networks in nature possess a remarkable amount of structure. Via a series of
data-driven discoveries, the cutting edge of network science has recently
progressed from positing that the random graphs of mathematical graph theory
might accurately describe real networks to the current viewpoint that networks
in nature are highly complex and structured entities. The identification of
high order structures in networks unveils insights into their functional
organization. Recently, Clauset, Moore, and Newman, introduced a new algorithm
that identifies such heterogeneities in complex networks by utilizing the
hierarchy that necessarily organizes the many levels of structure. Here, we
anchor their algorithm in a general community detection framework and discuss
the future of community detection.

categories: physics.soc-ph cond-mat.stat-mech physics.data-an q-bio.QM


title:
Creating and Verifying a Quantum Superposition in a Micro-optomechanical
  System

abstract:
  Micro-optomechanical systems are central to a number of recent proposals for
realizing quantum mechanical effects in relatively massive systems. Here we
focus on a particular class of experiments which aim to demonstrate massive
quantum superpositions, although the obtained results should be generalizable
to similar experiments. We analyze in detail the effects of finite temperature
on the interpretation of the experiment, and obtain a lower bound on the degree
of non-classicality of the cantilever. Although it is possible to measure the
quantum decoherence time when starting from finite temperature, an unambiguous
demonstration of a quantum superposition requires the mechanical resonator to
be in or near the ground state. This can be achieved by optical cooling of the
fundamental mode, which also provides a method to measure the mean phonon
number in that mode. We also calculate the rate of environmentally induced
decoherence and estimate the timescale for gravitational collapse mechanisms as
proposed by Penrose and Diosi. In view of recent experimental advances,
practical considerations for the realization of the described experiment are
discussed.


title: Content Algebras Over Commutative Rings With Zero-Divisors

abstract:
  Let $M$ be an $R$-module and $c$ the function from $M$ to the ideals of $R$
defined by $c(x) = \cap \lbrace I \colon I \text{is an ideal of} R \text{and} x
\in IM \rbrace $. $M$ is said to be a content $R$-module if $x \in c(x)M $, for
all $x \in M$. $B$ is called a content $R$-algebra, if it is a faithfully flat
and content $R$-module and it satisfies the Dedekind-Mertens content formula.
In this article, we prove some new results for content modules and algebras by
using ideal theoretic methods.


title: Biharmonic maps between doubly warped product manifolds

abstract:
  In this paper biharmonic maps between doubly warped product manifolds are
studied. We show that the inclusion maps of Riemannian manifolds $B$ and $F$
into the doubly warped product $_{f}B\times_{b}F$ can not be proper biharmonic
maps. Also we analyze the conditions for the biharmonicity of projections
$_{f}B\times_{b}F\to B$ and $_{f}B\times_{b}F\to F$, respectively. Some
characterizations for non-harmonic biharmonic maps are given by using product
of harmonic maps and warping metric. Specially, in the case of $f=1$, the
results for warped product in \cite{Balmus-mont} are obtained.


title:
Numerical evidence for unstable magnons at high fields in the Heisenberg
  antiferromagnet on the square lattice

abstract:
  We find evidence for decaying magnons at strong magnetic field in the square
lattice spin-1/2 Heisenberg antiferromagnet. The results are obtained using
Quantum Monte Carlo simulations combined with a Bayesian inference technique to
obtain dynamics and are consistent with predictions from spin wave theory.


title:
An algebraic formula for the intersection number of a polynomial
  immersion

abstract:
  There is presented an algorithm for computing the topological degree for a
large class of polynomial mappings. As an application there is given an
effective algebraic formula for the intersection number of a polynomial
immersion M --> R^2m, where M is an m-dimensional algebraic manifold.


title:
Self-consistency vanishes in the plateau regime of the bump-on-tail
  instability

abstract:
  Using the Vlasov-wave formalism, it is shown that self-consistency vanishes
in the plateau regime of the bump-on-tail instability if the plateau is broad
enough. This shows that, in contrast with the "turbulent trapping" Ansatz, a
renormalization of the Landau growth rate or of the quasilinear diffusion
coefficient is not necessarily related to the limit where the Landau growth
time becomes large with respect to the time of spreading of the particle
positions due to velocity diffusion.


title:
Single Horizon Black Hole "Laser" and a Solution of the Information Loss
  Paradox

abstract:
  In this work we show that single horizon black hole behaves as a "laser". It
is in many aspects conceptually analogous to Corley and Jacobson work on the
two horizon black hole "laser". We started by proposition that circumference of
the black hole horizon holds the natural (integer) quantum number of
corresponding reduced Compton's wave length of some boson systems in great
canonical ensemble. For macroscopic black hole ground state is practically
totally occupied while other states are practically totally unoccupied which is
a typical Bose condensation. Number of the systems in this condensate
represents black hole entropy. For microscopic black hole few lowest energy
levels are occupied with almost equivalent population (with negative chemical
potential) while all other energy states (with positive chemical potential) are
practically unoccupied. It implies that here not only spontaneous but also
stimulated emission of radiation comparable with spontaneous emission occurs.
By Hawking evaporation any macroscopic black hole turns out in a microscopic
black hole that yields, in a significant degree, coherent stimulated emission
of the radiation. It implies that by total black hole evaporation there is no
decoherence, i.e. information loss. Finally, a mass duality characteristic for
suggested black hole model corresponding to string T-duality is discussed.


title: A Lorentz and gauge invariant measure of laser intensity

abstract:
  Focussing on null fields as simple models of laser beams we discuss the
classical relativistic motion of charges in strong electromagnetic fields. We
suggest a universal, Lorentz and gauge invariant measure of laser intensity and
explicitly calculate and interpret it for crossed field, plane wave and vortex
models.


title:
Convergence of Implicit Difference Scheme for 1D Lagrangian
  Hydrodynamics coupled to Radiation Transport Equation

abstract:
  A fully implicit finite difference scheme has been developed to solve the
hydrodynamic equations coupled with radiation transport. Solution of the time
dependent radiation transport equation is obtained using the discrete ordinates
method and the energy flow into the Lagrangian meshes as a result of radiation
interaction is fully accounted for. A tridiagonal matrix system is solved at
each time step to determine the hydrodynamic variables implicitly. The results
obtained from this fully implicit radiation hydrodynamics code in the planar
geometry agrees well with the scaling law for radiation driven strong shock
propagation in aluminium. For the point explosion problem the self similar
solutions are compared with results for pure hydrodynamic case in spherical
geometry and the effect of radiation energy transfer is determined. Having,
thus, benchmarked the code, convergence of the method w.r.t. time step is
studied in detail and compared with the results of commonly used semi-implicit
method. It is shown that significant error reduction is feasible in the
implicit method in comparison to the semi-implicit method, though at the cost
of slightly more CPU time.


title: Derivation of a Fundamental Diagram for Urban Traffic Flow

abstract:
  Despite the importance of urban traffic flows, there are only a few
theoretical approaches to determine fundamental relationships between
macroscopic traffic variables such as the traffic density, the utilization, the
average velocity, and the travel time. In the past, empirical measurements have
primarily been described by fit curves. Here, we derive expected fundamental
relationships from a model of traffic flows at intersections, which suggest
that the recently measured fundamental diagrams for urban flows can be
systematically understood. In particular, this allows one to derive the average
travel time and the average vehicle speed as a function of the utilization
and/or the average number of delayed vehicles.


title: Quasi-Normal Modes for Logarithmic Conformal Field Theory

abstract:
  We generalize the one-to one correspondence between quasi normal modes in 3-
dimensional anti deSitter black holes and the poles of the retarded correlators
in the boundary conformal field theory to include logarithmic operators in the
latter. This analysis is carried out explicitly for the logarithmic mode in
chiral topologically massive gravity.


title:
Solving radiative transfer with line overlaps using Gauss Seidel
  algorithms

abstract:
  The improvement in observational facilities requires refining the modelling
of the geometrical structures of astrophysical objects. Nevertheless, for
complex problems such as line overlap in molecules showing hyperfine structure,
a detailed analysis still requires a large amount of computing time and thus,
misinterpretation cannot be dismissed due to an undersampling of the whole
space of parameters. We extend the discussion of the implementation of the
Gauss--Seidel algorithm in spherical geometry and include the case of hyperfine
line overlap. We first review the basics of the short characteristics method
that is used to solve the radiative transfer equations. Details are given on
the determination of the Lambda operator in spherical geometry. The
Gauss--Seidel algorithm is then described and, by analogy to the plan--parallel
case, we see how to introduce it in spherical geometry. Doing so requires some
approximations in order to keep the algorithm competitive. Finally, line
overlap effects are included. The convergence speed of the algorithm is
compared to the usual Jacobi iterative schemes. The gain in the number of
iterations is typically factors of 2 and 4 for the two implementations made of
the Gauss--Seidel algorithm. This is obtained despite the introduction of
approximations in the algorithm. A comparison of results obtained with and
without line overlaps for N2H+, HCN, and HNC shows that the J=3-2 line
intensities are significantly underestimated in models where line overlap is
neglected.


title: Lp-Solutions for Reected Backward Stochastic Differential Equations

abstract:
  This paper deals with the problem of existence and uniqueness of a solution
for a backward stochastic differential equation (BSDE for short) with one
reflecting barrier in the case when the terminal value, the generator and the
obstacle process are Lp-integrable with p in ]1,2[. To construct the solution
we use two methods: penalization and Snell envelope. As an application we
broaden the class of functions for which the related obstacle partial
differential equation problem has a unique viscosity solution.


title:
Form factors of integrable higher-spin XXZ chains and the affine
  quantum-group symmetry

abstract:
  We derive exactly scalar products and form factors for integrable higher-spin
XXZ chains through the algebraic Bethe-ansatz method. Here spin values are
arbitrary and different spins can be mixed. We show the affine quantum-group
symmetry, $U_q(\hat{sl_2})$, for the monodromy matrix of the XXZ spin chain,
and then obtain the exact expressions. Furthermore, through the quantum-group
symmetry we explicitly derive the diagonalized forms of the $B$ and $C$
operators in the $F$-basis for the spin-1/2 XXZ spin chain, which was
conjectured in the algebraic Bethe-ansatz calculation of the XXZ correlation
functions. The results should be fundamental in studying form factors and
correlation functions systematically for various solvable models associated
with the integrable XXZ spin chains.

categories: cond-mat.stat-mech hep-th math-ph math.MP math.QA nlin.SI quant-ph


title:
Universal criterion and phase diagram for switching a magnetic vortex
  core in soft magnetic nanodots

abstract:
  The universal criterion for ultrafast vortex-core switching between the up-
and down-core bistates in soft magnetic nanodots was investigated by
micromagnetic simulations along with analytical calculations. Vortex-core
switching occurs whenever the velocity of vortex-core motion reaches the
critical velocity that is expressed as (e.g. m/s for Permalloy), where Aex is
the exchange stiffness, and is the gyromagnetic ratio. On the basis of the
above results, phase diagrams for the vortex-core switching event and switching
times with respect to both the amplitude and frequency of applied circularly
rotating magnetic field were calculated, which offer practical guidance for
implementing nanodots in vortex states into future solid-state
information-storage devices.


title:
Magnetic interactions and high-field properties of Ag(2)VOP(2)O(7):
  frustrated alternating chain close to the dimer limit

abstract:
  We report on high-field magnetic properties of the silver vanadium phosphate
Ag(2)VOP(2)O(7). This compound has a layered crystal structure, but the
specific topology of the V-P-O framework gives rise to a one-dimensional spin
system, a frustrated alternating chain. Low-field magnetization measurements
and band structure calculations show that Ag(2)VOP(2)O(7) is close to the dimer
limit with the largest nearest-neighbor interaction of about 30 K. High-field
magnetization data reveal the critical fields \mu_0H_{c1} of about 23 T
(closing of the spin gap) and \mu_0H_{c2} of about 30 T (saturation by full
alignment of the magnetic moments). From H_{c1} to H_{c2} the magnetization
increases sharply similar to the system of isolated dimers. Thus, the magnetic
frustration in Ag(2)VOP(2)O(7) bears little influence on the high-field
properties of this compound.


title: Generalized spin bases for quantum chemistry and quantum information

abstract:
  Symmetry adapted bases in quantum chemistry and bases adapted to quantum
information share a common characteristics: both of them are constructed from
subspaces of the representation space of the group SO(3) or its double group
(i.e., spinor group) SU(2). We exploit this fact for generating spin bases of
relevance for quantum systems with cyclic symmetry and equally well for quantum
information and quantum computation. Our approach is based on the use of
generalized Pauli matrices arising from a polar decomposition of SU(2). This
approach leads to a complete solution for the construction of mutually unbiased
bases in the case where the dimension d of the considered Hilbert subspace is a
prime number. We also give the starting point for studying the case where d is
the power of a prime number. A connection of this work with the unitary group
U(d) and the Pauli group is brielly underlined.


title:
Linear family of Lie brackets on the space of matrices $Mat(n\times
  m,\K)$ and Ado's Theorem

abstract:
  In this paper we classify a linear family of Lie brackets on the space of
rectangular matrices $Mat(n\times m,\K)$ and we give an analogue of the Ado's
Theorem. We give also a similar classification on the algebra of the square
matrices $Mat(n, \K)$ and as a consequence, we prove that we can't built a
faithful representation of the $(2n+1)$-dimensional Heisenberg Lie algebra
$\mathfrak{H}_n$ in a vector space $V$ with $\dim V\leq n+1$. Finally, we prove
that in the case of the algebra of square matrices $Mat(n,\K)$, the
corresponding Lie algebras structures are a contraction of the canonical Lie
algebra $\mathfrak{gl}(n,\K)$.


title: Effective interactions of colloids on nematic films

abstract:
  The elastic and capillary interactions between a pair of colloidal particles
trapped on top of a nematic film are studied theoretically for large
separations $d$. The elastic interaction is repulsive and of quadrupolar type,
varying as $d^{-5}$. For macroscopically thick films, the capillary interaction
is likewise repulsive and proportional to $d^{-5}$ as a consequence of
mechanical isolation of the system comprised of the colloids and the interface.
A finite film thickness introduces a nonvanishing force on the system (exerted
by the substrate supporting the film) leading to logarithmically varying
capillary attractions. However, their strength turns out to be too small to be
of importance for the recently observed pattern formation of colloidal droplets
on nematic films.


title: Les (a,b)-alg\`ebres \`a homotopie pr\`es

abstract:
  We study in this article the concepts of algebra up to homotopy for a
structure defined by two operations $ \pt $ and $[, ]$. Having determined the
structure of $ G_\infty $ algebras and $ P_\infty $ algebras, we generalize
this construction and we define a structure of $ (a, b)$-algebra up to
homotopy. Given a structure of commutative and differential graded Lie algebra
for two shifts degree given by $a$ and $b$, we will give an explicit
construction of the associate algebra up to homotopy


title: DSR as an explanation of cosmological structure

abstract:
  Deformed special relativity (DSR) is one of the possible realizations of a
varying speed of light (VSL). It deforms the usual quadratic dispersion
relations so that the speed of light becomes energy dependent, with preferred
frames avoided by postulating a non-linear representation of the Lorentz group.
The theory may be used to induce a varying speed of sound capable of generating
(near) scale-invariant density fluctuations, as discussed in a recent Letter.
We identify the non-linear representation of the Lorentz group that leads to
scale-invariance, finding a universal result. We also examine the higher order
field theory that could be set up to represent it.


title: Inclusion of Yang-Mills Fields in String Corrected Supergravity

abstract:
  We consistently incorporate Yang Mills matter fields into string corrected
(deformed), D=10, N=1 Supergravity. We solve the Bianchi identities within the
framework of the modified beta function favored constraints to second order in
the string slope parameter $\g$ also including the Yang Mills fields. In the
torsion, curvature and H sectors we find that a consistent solution is readily
obtained with a Yang Mills modified supercurrent $A_{abc}$. We find a solution
in the F sector following our previously developed method.


title: Kaon Condensation with Lattice QCD

abstract:
  Kaon condensation may play an important role in the structure of hadronic
matter at densities greater than that of nuclear matter, as exist in the
interior of neutron stars. We present the results of the first lattice QCD
investigation of kaon condensation obtained by studying systems containing up
to twelve negatively charged kaons. Surprisingly, the properties of the
condensate that we calculate are remarkably well reproduced by leading order
chiral perturbation theory. In our analysis, we also determine the three-kaon
interaction from the multi-kaon systems and update our results for pion
condensates.


title: Magnesium doped helium nanodroplets

abstract:
  We have studied the structure of $^4$He droplets doped with magnesium atoms
using density functional theory. We have found that the solvation properties of
this system strongly depend on the size of the $^4$He droplet. For small drops,
Mg resides in a deep surface state, whereas for large size drops it is fully
solvated but radially delocalized in their interior. We have studied the $3s3p$
$^1$P$_1 \leftarrow 3s^2$ $^1$S$_0$ transition of the dopant, and have compared
our results with experimental data from laser induced fluorescence (LIF). Line
broadening effects due to the coupling of dynamical deformations of the
surrounding helium with the dipole excitation of the impurity are explicitly
taken into account. We show that the Mg radial delocalization inside large
droplets may help reconcile the apparently contradictory solvation properties
of magnesium as provided by LIF and electron-impact ionization experiments. The
structure of $^4$He drops doped with two magnesium atoms is also studied and
used to interpret the results of resonant two-photon-ionization (R2PI) and LIF
experiments. We have found that the two solvated Mg atoms do not easily merge
into a dimer, but rather form a weakly-bound state due to the presence of an
energy barrier caused by the helium environment that keep them some 9.5 \AA{}
apart, preventing the formation of the Mg$_2$ molecule. From this observation,
we suggest that Mg atoms in $^4$He drops may form, under suitable conditions, a
soft ``foam''-like aggregate rather than coalesce into a compact metallic
cluster. Our findings are in qualitative agreement with recent R2PI
experimental evidences. We predict that, contrarily, Mg atoms adsorbed in
$^3$He droplets do not form such metastable aggregates.


title: U(1)_R mediation from the flux compactification in six dimensions

abstract:
  We consider a supersymmetric completion of codimension-two branes with
nonzero tension in a 6D gauged supergravity. As a consequence, we obtain the
football solution with 4D Minkowski space as a new supersymmetric background
that preserves 4D N=1 SUSY. In the presence of brane multiplets, we derive the
4D effective supergravity action for the football background and show that the
remaining modulus can be stabilized by a bulk non-perturbative correction with
brane uplifting potentials at a zero vacuum energy. We find that the U(1)_R
mediation can be a dominant source of SUSY breaking for a brane scalar with
nonzero R charge.


title:
Large temperature dependence of the Casimir force at the metal-insulator
  transition

abstract:
  The dependence of the Casimir force on material properties is important for
both future applications and to gain further insight on its fundamental
aspects. Here we derive a general theory of the Casimir force for
low-conducting compounds, or poor metals. For distances in the micrometer
range, a large variety of such materials is described by universal equations
containing a few parameters: the effective plasma frequency, dissipation rate
of the free carriers, and electric permittivity in the infrared range. This
theory can also describe inhomogeneous composite materials containing small
regions with different conductivity. The Casimir force for mechanical systems
involving samples made with compounds that have a metal-insulator transition
shows an abrupt large temperature dependence of the Casimir force within the
transition region, where metallic and dielectric phases coexist.


title: Dynamical vertex approximation -- an introduction

abstract:
  We give an elementary introduction to a recent diagrammatic extension of
dynamical mean field theory (DMFT) coined dynamical vertex approximation
(D$\Gamma$A). This approach contains the important local correlations of DMFT,
giving, among others, rise to quasiparticle renormalizations, Mott-Hubbard
transitions and magnetism, but also non-local correlations beyond. The latter
are at the very essence of many physical phenomena in strongly correlated
elecectron systems. As correlations are treated equally on all length scales,
D$\Gamma$A allows us to describe physical phenomena such as magnons, quantum
criticality, and the interplay between antiferromagnetism and
superconductivity. We review results hitherto obtained for the Hubbard model in
dimensions d=3, 2, and 1.


title:
Electronic liquid crystal state in the high-temperature superconductor
  YBCO(6.45)

abstract:
  Electronic phases with symmetry properties matching those of conventional
liquid crystals have recently been discovered in transport experiments on
semiconductor heterostructures and metal oxides at milli-Kelvin temperatures.
We report the spontaneous onset of a onedimensional, incommensurate modulation
of the spin system in the high-temperature superconductor YBa2Cu3O6.45 upon
cooling below ~150 K, while static magnetic order is absent above 2 K. The
evolution of this modulation with temperature and doping parallels that of the
in-plane anisotropy of the resistivity, indicating an electronic nematic phase
that is stable over a wide temperature range. The results suggest that soft
spin fluctuations are a microscopic route towards electronic liquid crystals,
and nematic order can coexist with high-temperature superconductivity in
underdoped cuprates.


title:
An Assessment of Broadband Optical Colours as Age Indicators for Star
  Clusters

abstract:
  We present an empirical assessment of the use of broadband optical colours as
age indicators for unresolved extragalactic clusters and investigate stochastic
sampling effects on integrated colours. We use the integrated properties of
Galactic open clusters as models for unresolved extragalactic clusters. The
population synthesis code Starburst99 (Leitherer et al. 1999) and four optical
colours were used to estimate how well we can recover the ages of 62
well-studied Galactic open clusters with published ages. We provide a method
for estimating the ages of unresolved clusters and for reliably determining the
uncertainties in the age estimates. Our results support earlier conclusions
based on comparisons to synthetic clusters, namely the (U-B) colour is critical
to the estimation of the ages of star forming regions. We compare the observed
optical colours with those obtained from Starburst99 using the published ages
and get good agreement. The scatter in the (B-V)_observed-(B-V)_model is larger
for lower luminosity clusters, perhaps due to stochastic effects.


title: A symplectic Gysin sequence

abstract:
  We use the theory of pseudo-holomorphic quilts to establish a counterpart, in
symplectic Floer homology, to the Gysin sequence for the homology of a
sphere-bundle. In a motivating class of examples, this "symplectic Gysin
sequence" is precisely analogous to an exact sequence describing the behaviour
of Seiberg-Witten monopole Floer homology for 3-manifolds under connected sum.


title:
The first principles calculations of the atomic and electronic structure
  of cubic and orthorhombic LaMnO3 surfaces

abstract:
  Combining GGA-plane wave approach as implemented into the VASP - 4.6.19
computer code with a slab model, we studied in detail the atomic and electronic
structure of the LaMnO3 surfaces, in both cubic and orthorhombic phases. The
results obtained are compared with similar studies for other ABO3-perovskites.


title: Foreground analysis of the WMAP three-year data with FASTICA

abstract:
  We present an analysis of the foreground emission present in the WMAP 3-year
data as determined by the method of Independent Component Analysis. We derived
coupling coefficients between the WMAP data and foreground templates which are
then used to infer the spectral behaviour for three foreground components --
synchrotron, anomalous dust-correlated emission and free-free. For the first
two components, we find values consistent with previous results although
slightly steeper. We confirm the inconsistency in the scaling between the Ha
template and free-free emission at K- and Ka-bands where an electron
temperature of ~ 4000 K is indicated. We also see evidence of significantly
flatter spectral behaviour to higher frequencies than expected theoretically
and previously noted by Dobler et al.(2008a), but only when analysing the Kp2
sky coverage. We further apply FASTICA 'iteratively', using data pre-cleaned
using foreground templates scaled to the WMAP frequencies by coupling
coefficients determined by a prior FASTICA analysis. This multi-frequency
analysis allows us to determine the presence of residual foreground emission
not traced by the templates. We confirm the existence of a component spatially
distributed along the Galactic plane and particularly enhanced near the center
(the 'WMAP haze'). This emission is less extended when using the WMAP K-Ka data
as the synchrotron template confirming that it can be considered a better
template for foreground cleaning of the WMAP data. However its use complicates
the physical interpretation of the nature of the foreground emission and
residuals. since it contains a mixture of several, physically distinct emission
mechanisms.


title:
Shear and Vorticity in an Accelerating Brans-Dicke Lambda-Universe with
  Torsion

abstract:
  We study accelerating Universes with power-law scale-factors. We include
shear and vorticity, a cosmological "constant" term, and spin from torsion, as
in Einstein-Cartan's theory when a scalar-field of Brans-Dicke type acts in the
model. We find a "no-hair" result, for shear and vorticity; we also make
contact with the alternative Machian picture of the Universe. Keywords:
Cosmology; Einstein; Brans-Dicke; Cosmological term; Shear; Spin; Vorticity;
Inflation; Einstein-Cartan; Torsion; Accelerating Universe


title: A basic swimmer at low Reynolds number

abstract:
  Swimming and pumping at low Reynolds numbers are subject to the "Scallop
theorem", which states that there will be no net fluid flow for time reversible
motions. Living organisms such as bacteria and cells are subject to this
constraint, and so are existing and future artificial "nano-bots" or
microfluidic pumps. We study a very simple mechanism to induce fluid pumping,
based on the forced motion of three colloidal beads through a cycle that breaks
time-reversal symmetry. Optical tweezers are used to vary the inter-bead
distance. This model is inspired by a strut-based theoretical swimmer proposed
by Najafi and Golestanian [Phys.Rev. E, 69, 062901, 2004], but in this work the
relative softness of the optical trapping potential introduces a new control
parameter. We show that this system is able to generate flow in a controlled
fashion, characterizing the model experimentally and numerically.