title: Smart detectors for Monte Carlo radiative transfer

abstract:
  Many optimization techniques have been invented to reduce the noise that is
inherent in Monte Carlo radiative transfer simulations. As the typical
detectors used in Monte Carlo simulations do not take into account all the
information contained in the impacting photon packages, there is still room to
optimize this detection process and the corresponding estimate of the surface
brightness distributions. We want to investigate how all the information
contained in the distribution of impacting photon packages can be optimally
used to decrease the noise in the surface brightness distributions and hence to
increase the efficiency of Monte Carlo radiative transfer simulations.
  We demonstrate that the estimate of the surface brightness distribution in a
Monte Carlo radiative transfer simulation is similar to the estimate of the
density distribution in an SPH simulation. Based on this similarity, a recipe
is constructed for smart detectors that take full advantage of the exact
location of the impact of the photon packages. Several types of smart
detectors, each corresponding to a different smoothing kernel, are presented.
We show that smart detectors, while preserving the same effective resolution,
reduce the noise in the surface brightness distributions compared to the
classical detectors. The most efficient smart detector realizes a noise
reduction of about 10%, which corresponds to a reduction of the required number
of photon packages (i.e. a reduction of the simulation run time) of 20%. As the
practical implementation of the smart detectors is straightforward and the
additional computational cost is completely negligible, we recommend the use of
smart detectors in Monte Carlo radiative transfer simulations.


title:
Two-dimensional relativistic hydrogenic atoms: A complete set of
  constants of motion

abstract:
  The complete set of operators commuting with the Dirac Hamiltonian and exact
analytic solution of the Dirac equation for the two-dimensional Coulomb
potential is presented. Beyond the eigenvalue $\mu$ of the operator $j_{z}$,
two quantum numbers $\eta$ and $\kappa$ are introduced as eigenvalues of
hermitian operators $P=\beta\sigma_{z}'$ and $K=\beta(\sigma_{z}'l_{z}+1/2)$,
respectively. The classification of states according to the full set of
constants of motion without referring to the non-relativistic limit is
proposed. The linear Paschen-Back effect is analyzed using exact field-free
wave-functions as a zero-order approximation.


title: Spontaneous exciton condensation in 1T-TiSe2: a BCS-like approach

abstract:
  Recently strong evidence has been found in favor of a BCS-like condensation
of excitons in 1\textit{T}-TiSe$_2$. Theoretical photoemission intensity maps
have been generated by the spectral function calculated within the excitonic
condensate phase model and set against experimental angle-resolved
photoemission spectroscopy data. Here, the calculations in the framework of
this model are presented in detail. They represent an extension of the original
excitonic insulator phase model of J\'erome \textit{et al.} [Phys. Rev. {\bf
158}, 462 (1967)] to three dimensional and anisotropic band dispersions. A
detailed analysis of its properties and further comparison with experiment are
also discussed


title:
Again on hidden sector of the Universe, accessible through photonic
  portal

abstract:
  We describe more precisely the mechanism of spontaneous mass generation in
the previously proposed model of hidden sector of the Universe. The hidden
sector is conjectured to consist of sterile spin-1/2 fermions (sterinos) whose
mass is spontaneously generated by sterile scalar bosons (sterons), while their
interactions are mediated by sterile antisymmetric-tensor bosons (A bosons).
Such a sector communicates with the familiar Standard Model sector through a
photonic portal acting weakly between both sectors (but stronger than the
universal gravity). This is due to photons which, beside sterinos and sterons,
contribute to the source of the A bosons. Sterinos can be candidates for
thermal cold dark matter. They can be also produced in sterino-antisterino
pairs through virtual photons emitted in high-energy collisions of Standard
Model charged particles. Sterinos display a tiny magnetic moment spontaneously
generated by sterons.


title: Entanglement Measures for Intermediate Separability of Quantum States

abstract:
  We present a family of entanglement measures R_m which act as indicators for
separability of n-qubit quantum states into m subsystems for arbitrary 2 \leq m
\leq n. The measure R_m vanishes if the state is separable into m subsystems,
and for m = n it gives the Meyer-Wallach measure while for m = 2 it reduces, in
effect, to the one introduced recently by Love et al. The measures R_m are
evaluated explicitly for the GHZ state and the W state (and its modifications,
the W_k states) to show that these globally entangled states exhibit rather
distinct behaviors under the measures, indicating the utility of the measures
R_m for characterizing globally entangled states as well.


title:
Quasinormal modes from potentials surrounding the charged dilaton black
  hole

abstract:
  We clarify the purely imaginary quasinormal frequencies of a massless scalar
perturbation on the 3D charged-dilaton black holes. This case is quite
interesting because the potential-step appears outside the event horizon
similar to the case of the electromagnetic perturbations on the large
Schwarzschild-AdS black holes. It turns out that the potential-step type
provides the purely imaginary quasinormal frequencies, while the
potential-barrier type gives the complex quasinormal modes.


title: Quantum Private Queries: security analysis

abstract:
  We present a security analysis of the recently introduced Quantum Private
Query (QPQ) protocol. It is a cheat sensitive quantum protocol to perform a
private search on a classical database. It allows a user to retrieve an item
from the database without revealing which item was retrieved, and at the same
time it ensures data privacy of the database (the information that the user can
retrieve in a query is bounded and does not depend on the size of the
database). The security analysis is based on information-disturbance tradeoffs
which show that whenever the provider tries to obtain information on the query,
the query (encoded into a quantum system) is disturbed so that the person
querying the database can detect the privacy violation.


title: Optimising LISA orbits: The projectile solution

abstract:
  LISA is a joint space mission of the NASA and the ESA for detecting low
frequency gravitational waves (GW) in the band $10^{-5} - 0.1$ Hz. The proposed
mission will use coherent laser beams which will be exchanged between three
identical spacecraft forming a giant (almost) equilateral triangle of side $5
\times 10^6$ kilometres. The plane of the triangle will make an angle of $\sim
60^{\circ}$ with the plane of the ecliptic. The spacecraft constituting LISA
will be freely floating in the ambient gravitational field of the Sun and other
celestial bodies. To achieve the requisite sensitivity, the spacecraft
formation should remain stable, one requirement being, the distances between
spacecraft should remain as constant as possible - that is the flexing of the
arms should be minimal. In this paper we present a solution - the projectile
solution - which constrains the flexing of the arms to below 5.5 metres/sec in
a three year mission period. This solution is obtained in the field of the Sun
and Earth only, which principally affect the motion of the spacecraft,
especially the flexing of LISA's arms.


title:
Temperature dependence of the excitonic insulator phase model in
  1T-TiSe2

abstract:
  Recently, detailed calculations of the excitonic insulator phase model
adapted to the case of 1\textit{T}-TiSe$_2$ have been presented. Through the
spectral function theoretical photoemission intensity maps can be generated
which are in very good agreement with experiment [Phys. Rev. Lett. {\bf 99},
(2007) 146403]. In this model, excitons condensate in a BCS-like manner and
give rise to a charge density wave, characterized by an order parameter. Here,
we assume an analytical form of the order parameter, allowing to perform
temperature dependent calculations. The influence of this order parameter on
the electronic spectral function, to be observed in photoemission spectra, is
discussed. The resulting chemical potential shift and an estimation of the
resistivity are also shown.


title:
Hamiltonian Dynamics of the Protein Chain and Normal Modes of
  Alpha-Helix and Beta-Sheet

abstract:
  We use the torsional angles of the protein chain as generalized coordinates
in the canonical formalism, derive canonical equations of motion, and
investigate the coordinate dependence of the kinetic energy expressed in terms
of the canonical momenta. We use the formalism to compute the normal-frequency
distributions of the alpha-helix and the beta-sheet, under the assumption that
they are stabilized purely through hydrogen bonding. Comparison of their free
energies show the existence of a phase transition between the alpha-helix and
the beta-sheet at a critical temperature.


title:
Discrete, q-difference deformations of associative algebras and
  integrable systems

abstract:
  Discrete and q-difference deformations of the structure constants for a class
of associative noncommutative algebras are studied. It is shown that these
deformations are governed by a central system of discrete or q-difference
equations which in particular cases represent discrete and q-difference
versions of the oriented associativity equation. It is demonstrated also that
the celebrated Hirota-Miwa bilinear equation for the AKP and BKP hierarchies
describes discrete deformations of certain finite-dimensional algebras.


title:
High precision X-ray logN-logS distributions: implications for the
  obscured AGN population

abstract:
  We have constrained the extragalactic source count distributions over a broad
range of X-ray fluxes and in various energy bands to test whether the
predictions from X-ray background synthesis models agree with the observational
constraints provided by our measurements. We have used 1129 XMM-Newton
observations at |b|>20 deg covering a sky area of 132.3 deg^2 to compile the
largest complete samples of X-ray objects to date in the 0.5-1 keV, 1-2 keV,
2-4.5 keV, 4.5-10 keV, 0.5-2 keV and 2-10 keV energy bands. Our survey includes
in excess of 30,000 sources down to ~10^-15 erg/cm^2/s below 2 keV and down to
~10^{-14} erg/cm^2/s above 2 keV. A break in the source count distributions was
detected in all energy bands except the 4.5-10 keV band. An analytical model
comprising 2 power-law components cannot adequately describe the curvature seen
in the source count distributions. The shape of the logN(>S)-logS is strongly
dependent on the energy band with a general steepening apparent as we move to
higher energies. This is due to non-AGN populations, comprised mainly of stars
and clusters of galaxies, contribute up to 30% of the source population at
energies <2 keV and at fluxes >10^{-13} erg/cm^2/s, and these populations of
objects have significantly flatter source count distributions than AGN. We find
a substantial increase in the relative fraction of hard X-ray sources at higher
energies, from >55% below 2 keV to >77% above 2 keV. However the majority of
sources detected above 4.5 keV still have significant flux below 2 keV.
Comparison with predictions from the synthesis models suggest that the models
might be overpredicting the number of faint absorbed AGN, which would call for
fine adjustment of some model parameters such as the obscured to unobscured AGN
ratio and/or the distribution of column densities at intermediate obscuration.


title: On parallel submanifolds of symmetric spaces

abstract:
  Due to its length and several inaccuracies, this article is no longer
suggested for reading. Moreover, in the meantime certain results presented
herein could be improved by the author in a non-trivial fashion.
  Instead, the reader is referred to the following two articles:
  The extrinsic holonomy Lie algebra of a parallel submanifold
(arXiv:0904.2611),
  Extrinsic homogeneity of parallel submanifolds (arXiv:0904.2636).


title:
Global stability and optimisation of a general impulsive biological
  control model

abstract:
  An impulsive model of augmentative biological control consisting of a general
continuous predator-prey model in ordinary differential equations augmented by
a discrete part describing periodic introductions of predators is considered.
It is shown that there exists an invariant periodic solution that corresponds
to prey eradication and a condition ensuring its global asymptotic stability is
given. An optimisation problem related to the preemptive use of augmentative
biological control is then considered. It is assumed that the per time unit
budget of biological control (i.e. the number of predators to be released) is
fixed and the best deployment of this budget is sought after in terms of
release frequency. The cost function to be minimised is the time taken to
reduce an unforeseen prey (pest) invasion under some harmless level. The
analysis shows that the optimisation problem admits a countable infinite number
of solutions. An argumentation considering the required robustness of the
optimisation result is then conducted and it is shown that the best deployment
is to use as frequent (and thus as small) as possible predator introductions.


title: GMC formation by agglomeration and self gravity

abstract:
  We investigate the formation of GMCs in spiral galaxies through both
agglomeration of clouds in the spiral arms, and self gravity. The simulations
presented include two-fluid models, which contain both cold and warm gas,
although there is no heating or cooling between them. We find agglomeration is
predominant when both the warm and cold components of the ISM are effectively
stable to gravitational instabilities. In this case, the spacing (and
consequently mass) of clouds and spurs along the spiral arms is determined by
the orbits of the gas particles and correlates with their epicyclic radii (or
equivalently spiral shock strength). Notably GMCs formed primarily by
agglomeration tend to be unbound associations of many smaller clouds, which
disperse upon leaving the spiral arms. These GMCs are likely to be more massive
in galaxies with stronger spiral shocks or higher surface densities. GMCs
formed by agglomeration are also found to exhibit both prograde and retrograde
rotation, a consequence of the clumpiness of the gas. At higher surface
densities, self gravity becomes more important in arranging both the warm and
cold gas into clouds and spurs, and determining the properties of the most
massive GMCs. These massive GMCs can be distinguished by their higher angular
momentum, exhibit prograde rotation and are more bound. For a 20 M$_{\odot}$
pc$^{-2}$ disc, the spacing between the GMCs fits both the agglomeration and
self gravity scenarios, as the maximum unstable wavelength of gravitational
perturbations in the warm gas is similar to the spacing found when GMCs form
solely by agglomeration.


title: The Spatial Evolution of Stellar Structures in the LMC/SMC

abstract:
  We present an analysis of the spatial distribution of various stellar
populations within the Large and Small Magellanic Clouds. We use optically
selected stellar samples with mean ages between ~9 and ~1000 Myr, and existing
stellar cluster catalogues to investigate how stellar structures form and
evolve within the LMC/SMC. We use two statistical techniques to study the
evolution of structure within these galaxies, the $Q$-parameter and the
two-point correlation function (TPCF). In both galaxies we find the stars are
born with a high degree of substructure (i.e. are highly fractal) and that the
stellar distribution approaches that of the 'background' population on
timescales similar to the crossing times of the galaxy (~80/150 Myr for the
SMC/LMC respectively). By comparing our observations to simple models of
structural evolution we find that 'popping star clusters' do not significantly
influence structural evolution in these galaxies. Instead we argue that general
galactic dynamics are the main drivers, and that substructure will be erased in
approximately the crossing time, regardless of spatial scale, from small
clusters to whole galaxies. This can explain why many young Galactic clusters
have high degrees of substructure, while others are smooth and centrally
concentrated. We conclude with a general discussion on cluster 'infant
mortality', in an attempt to clarify the time/spatial scales involved.


title:
Superconductivity-enhanced bias spectroscopy in carbon nanotube quantum
  dots

abstract:
  We study low-temperature transport through carbon nanotube quantum dots in
the Coulomb blockade regime coupled to niobium-based superconducting leads. We
observe pronounced conductance peaks at finite source-drain bias, which we
ascribe to elastic and inelastic cotunneling processes enhanced by the
coherence peaks in the density of states of the superconducting leads. The
inelastic cotunneling lines display a marked dependence on the applied gate
voltage which we relate to different tunneling-renormalizations of the two
subbands in the nanotube. Finally, we discuss the origin of an especially
pronounced sub-gap structure observed in every fourth Coulomb diamond.


title: Encryption via Entangled states belonging to Mutually Unbiased Bases

abstract:
  We consider particular entanglement of two particles whose state vectors are
in bases that are mutually unbiased (MUB), i.e. "that exhibit maximum degree of
incompatibility" (J.Schwinger,Nat. Ac. Sci. (USA), 1960)). We use this link
between entanglement and MUB to outline a protocol for secure key distribution
among the parties that share these entangled states. The analysis leads to an
association of entangled states and states in an MUB set: both carry the same
labels.


title: On the relation between geometric and deformation quantization

abstract:
  In this paper we investigate the possibility of constructing a complete
quantization procedure consisting of geometric and deformation quantization.
The latter assigns a noncommutative algebra to a symplectic manifold, by
deforming the ordinary pointwise product of functions, whereas geometric
quantization is a prescription for the construction of a Hilbert space and a
few quantum operators, starting from a symplectic manifold. We determine under
which conditions it is possible to define a representation of the deformed
algebra on this Hilbert space, thereby to extend the small class of quantizable
observables in geometric quantization to all smooth functions, as well as to
give a natural representation of the algebra. In particular we look at the
special cases of a cotangent bundle and a K\"ahler manifold.


title:
Finite size effects for the gap in the excitation spectrum of the
  one-dimensional Hubbard model

abstract:
  We study finite size effects for the gap of the quasiparticle excitation
spectrum in the weakly interacting regime one-dimensional Hubbard model with
on-site attraction. Two type of corrections to the result of the thermodynamic
limit are obtained. Aside from a power law (conformal) correction due to
gapless excitations which behaves as $1/N_a$, where $N_a$ is the number of
lattice sites, we obtain corrections related to the existence of gapped
excitations. First of all, there is an exponential correction which in the
weakly interacting regime ($|U|\ll t$) behaves as $\sim \exp (-N_a
\Delta_{\infty}/4 t)$ in the extreme limit of $N_a \Delta_{\infty} /t \gg 1$,
where $t$ is the hopping amplitude, $U$ is the on-site energy, and
$\Delta_{\infty}$ is the gap in the thermodynamic limit. Second, in a finite
size system a spin-flip producing unpaired fermions leads to the appearance of
solitons with non-zero momenta, which provides an extra (non-exponential)
contribution $\delta$. For moderate but still large values of
$N_a\Delta_{\infty} /t$, these corrections significantly increase and may
become comparable with the $1/N_a$ conformal correction. Moreover, in the case
of weak interactions where $\Delta_{\infty}\ll t$, the exponential correction
exceeds higher order power law corrections in a wide range of parameters,
namely for $N_a\lesssim (8t/\Delta_{\infty})\ln(4t/|U|)$, and so does $\delta$
even in a wider range of $N_a$. For sufficiently small number of particles,
which can be of the order of thousands in the weakly interacting regime, the
gap is fully dominated by finite size effects.


title: The nature of the methanol maser ring G23.657-00.127

abstract:
  Methanol masers are associated with young high-mass stars and are an
important tool for investigating the process of massive star formation. The
recently discovered methanol maser ring in G23.657-00.127 provides an excellent
``laboratory'' for a detailed study of the nature and physical origin of
methanol maser emission, as well as parallax and proper motion measurements.
Multi-epoch observations of the 12.2 GHz methanol maser line from the ring were
conducted using the Very Long Baseline Array. Interferometric observations with
milliarcsecond resolution enabled us to track single maser spots in great
detail over a period of 2 years. We have determined the trigonometric parallax
of G23.657-00.127 to be 0.313+/-0.039 mas, giving a distance of
3.19{+0.46}{-0.35} kpc. The proper motion of the source indicates that it is
moving with the same circular velocity as the LSR, but it shows a large
peculiar motion of about 35 km/s toward the Galactic center.


title: Protocol Channels

abstract:
  Covert channel techniques are used by attackers to transfer data in a way
prohibited by the security policy. There are two main categories of covert
channels: timing channels and storage channels. This paper introduces a new
storage channel technique called a protocol channel. A protocol channel
switches one of at least two protocols to send a bit combination to a
destination. The main goal of a protocol channel is that packets containing
covert information look equal to all other packets within a network, what makes
a protocol channel hard to detect.


title:
$f(R)$-Cosmolgy from Early Universe Upto Future Cosmic Collapse and its
  Avoidance

abstract:
  In the present model, a unified picture of cosmology from early inflation to
late acceleration is obtained from $ f(R)-$ gravity with non-linear terms $ R^2
$ and $ R^5 $ of scalar curvature $R$. It is discussed that elementary
particles and radiation are produced during early inflation. The emitted
radiation thermalizes the universe to a very high temperature $ \sim
10^{18}{\rm GeV}$. The exit of the universe from inflationary phase is followed
by deceleration due to radiation-dominance heralding the standard cosmology
with background radiation having the initial temperature $ \sim 10^{18}{\rm
GeV}$. It is found that dark matter is induced by curvature and baryonic matter
is produced during inflation. Radiation-dominated phase is followed by
deceleration due to matter-dominance. The curvature-induced phantom dark energy
dominates at the red-shift $ z = 0.303 $ causing the late acceleration. It is
found that the universe will collapse in future. Further, it is investigated
that back-reaction of quantum particles produced near the collapse time can
avoid cosmic collapse and the universe will escape to revival of the state of
early universe.


title: Quantum Covers in Quantum Measure Theory

abstract:
  In standard measure theory the measure on the base set Omega is normalised to
one, which encodes the statement that "Omega happens". Moreover, the rules
imply that the measure of any subset A of Omega is strictly positive if and
only if A cannot be covered by a collection of subsets of zero measure. In
quantum measure theory on the other hand, simple examples suffice to
demonstrate that this is no longer true. We propose an appropriate
generalisation of a cover to quantum measure theory, the {\sl quantum cover},
which in addition to being a cover of A, satisfies the property that if every
one of its elements has zero quantum measure, then so does A. We show that a
large class of inextendible antichains in the associated powerset lattice
provide quantum covers for Omega, for a quantum measure that derives from a
strongly positive decoherence functional. Quantum covers, moreover, give us a
new perspective on the Peres-Kochen-Specker theorem and its role in the
anhomomorphic logic approach to quantum interpretation.


title:
Gelfand transforms of SO(3)-invariant Schwartz functions on the free
  group N_{3,2}

abstract:
  The spectrum of a Gelfand pair $(K\ltimes N, K)$, where $N$ is a nilpotent
group, can be embedded in a Euclidean space. We prove that in general, the
Schwartz functions on the spectrum are the Gelfand transforms of Schwartz
$K$-invariant functions on $N$. We also show the converse in the case of the
Gelfand pair $(SO(3)\ltimes N_{3,2}, SO(3))$, where $N_{3,2}$ is the free
two-step nilpotent Lie group with three generators. This extends recent results
for the Heisenberg group.


title:
511 keV $\gamma$-ray emission from the galactic bulge by MeV
  millicharged dark matter

abstract:
  We propose a possible explanation for the recently observed anomalous 511 keV
line with a new "millicharged" fermion. This new fermion is light [${\cal
O}({\rm MeV})$]. Nevertheless, it has never been observed by any collider
experiments by virtue of its tiny electromagnetic charge $\epsilon e$. In
particular, we constrain parameters of this millicharged particle if the 511
keV cosmic $\gamma$-ray emission from the galactic bulge is due to positron
production from this new particle.


title:
Modification of the 21-cm power spectrum by X-rays during the epoch of
  reionisation

abstract:
  We incorporate a contribution to reionization from X-rays within analytic and
semi-numerical simulations of the 21-cm signal arising from neutral hydrogen
during the epoch of reionization. We explore the impact that X-ray ionizations
have on the power spectrum (PS) of 21-cm fluctuations by varying both the
average X-ray MFP and the fractional contribution of X-rays to reionization. In
general, prior to the epoch when the intergalactic medium is dominated by
ionized regions (H {\sevensize II} regions), X-ray-induced ionization enhances
fluctuations on spatial scales smaller than the X-ray MFP, provided that X-ray
heating does not strongly supress galaxy formation. Conversely, at later times
when \H2 regions dominate, small-scale fluctuations in the 21-cm signal are
suppressed by X-ray ionization. Our modelling also shows that the modification
of the 21-cm signal due to the presence of X-rays is sensitive to the relative
scales of the X-ray MFP, and the characteristic size of \H2 regions. We
therefore find that X-rays imprint an epoch and scale-dependent signature on
the 21-cm PS, whose prominence depends on fractional X-ray contribution. The
degree of X-ray heating of the IGM also determines the extent to which these
features can be discerned. We show that the MWA will have sufficient
sensitivity to detect this modification of the PS, so long as the X-ray photon
MFP falls within the range of scales over which the array is most sensitive
($\sim0.1$ Mpc$^{-1}$). In cases in which this MFP takes a much smaller value,
an array with larger collecting area would be required.


title:
European VLBI Network observations of 6.7-GHz methanol masers in a
  candidate circumstellar disc

abstract:
  The first high-resolution (5 mas) VLBI observations of 6.7-GHz methanol
masers in DR21(OH)N, a candidate circumstellar disc around a very young massive
star, are presented. Previous observations of these masers at 50 mas angular
resolution revealed a rotating structure at the position of a candidate massive
protostar, with a well-sampled position-velocity diagram suggesting Keplerian
rotation. Observations presented here using the European VLBI Network (EVN)
have provided the first high angular resolution maps of the masers, providing a
test for the disc hypothesis and the Gaussian centroiding technique. The EVN
maps have confirmed the shape of the disc and its rotation curve. Weaker maser
emission seen previously with MERLIN between the two main spectral peaks is
seen in the EVN total power spectrum, but is absent in the cross-power
spectrum. This suggests that the spatially extended emission is resolved out by
the EVN. The rotating disc is coincident with a Class I massive (proto)star and
at the implied centre of an outflow traced by two bow shocks. We discuss the
impact of this result on the massive stellar accretion disc hypothesis and on
the validity of the centroiding technique to determine the structures of
unresolved masers using compact radio interferometric arrays.


title: Stability of nonlinear one-dimensional laser pulse solitons in a plasma

abstract:
  In a recent one-dimensional numerical fluid simulation study [Saxena et al.,
Phys. Plasmas 13,032309 (2006)], it was found that an instability is associated
with a special class of one-dimensional nonlinear solutions for modulated light
pulses coupled to electron plasma waves in a relativistic cold plasma model. It
is shown here that the instability can be understood on the basis of the
stimulated Raman scattering phenomenon and the occurrence of density bursts in
the trailing edge of the modulated structures are a manifestation of an
explosive instability arising from a nonlinear phase mixing mechanism.


title:
Various Carbon to Carbon Bond Lengths Inter-related via the Golden
  Ratio, and their Linear Dependence on Bond Energies

abstract:
  This work presents the relations between the carbon to carbon bond lengths in
the single, double and triple bonds and in graphite, butadiene and benzene. The
Golden ratio, which was shown to divide the Bohr radius into two parts
pertaining to the charged particles, the electron and proton, and to divide
inter-atomic distances into their cationic and anionic radii, also plays a role
in the carbon-carbon bonds and in the ionic/polar character of those in
graphite, butadiene and benzene. Further, the bond energies of the various CC
bonds are shown to vary linearly with the bond lengths.


title: The Classification of Special Cohen-Macaulay Modules

abstract:
  In this paper we completely classify all the special Cohen-Macaulay (=CM)
modules corresponding to the exceptional curves in the dual graph of the
minimal resolutions of all two dimensional quotient singularities. In every
case we exhibit the specials explicitly in a combinatorial way. Our result
relies on realizing the specials as those CM modules whose first Ext group
vanishes against the ring R, thus reducing the problem to combinatorics on the
AR quiver; such possible AR quivers were classified by Auslander and Reiten. We
also give some general homological properties of the special CM modules and
their corresponding reconstruction algebras.


title: Photometry and polarimetry of the nucleus of comet 2P/Encke

abstract:
  Broadband imaging photometry, and broadband and narrowband linear polarimetry
was measured for the nucleus of 2P/Encke over the phase-angle range 4 - 28 deg.
An analysis of the point spread function of the comet reveals only weak coma
activity, corresponding to a dust production of the order of 0.05 kg/s. The
nucleus displays a color independent photometric phase function of almost
linear slope. The absolute R filter magnitude at zero phase angle is 15.05 +/-
0.05, and corresponds to an equivalent radius for the nucleus of 2.43 +/- 0.06
km (for an adopted albedo of 0.047). The nucleus color V - R is 0.47 +/- 0.07,
suggesting a spectral slope of 11 +/- 8 %/100nm. The phase function of linear
polarimetry in the V and R filters shows a widely color independent linear
increase with phase angle (0.12 +/- 0.02%/deg). We find discrepancies in the
photometric and polarimetric parameters between 2P/Encke and other minor bodies
in the solar system, which may indicate significant differences in the surface
material properties and light-scattering behavior of the bodies.
  The linear polarimetric phase function of 2P/Encke presented here is the
first ever measured for a cometary nucleus, and its analysis encourages future
studies of cometary nuclei in order to characterize the light-scattering
behavior of comets on firm empirical grounds and provide suitable input to a
comprehensive modeling of the light scattering by cometary surfaces.


title: Keller's Conjecture on the Existence of Columns in Cube Tilings of R^n

abstract:
  It is shown that if n<7, then each tiling of R^n by translates of the unit
cube [0,1)^n contains a column; that is, a family of the form
{[0,1)^n+(s+ke_i): k \in Z}, where s \in R^n, e_i is an element of the standard
basis of R^n and Z is the set of integers.


title: Dissecting Individual Ligand-Receptor Bonds with a Laminar Flow Chamber

abstract:
  The most important function of proteins may well be to bind to other
biomolecules. It has long been felt that kinetic rates of bond formation and
dissociation between soluble receptors and ligands might account for most
features of the binding process. Only theoretical considerations allowed to
predict the behaviour of surface-attached receptors from the properties of
soluble forms. During the last decade, experimental progress essentially based
on flow chambers, atomic force microscopes or biomembrane force probes allowed
direct analysis of biomolecule interaction at the single bond level and gave
new insight into previously ignored features such as bond mechanical properties
or energy landscapes. The aim of this review is (i) to describe the main
advances brought by laminar flow chambers, including information on bond
response to forces, multiplicity of binding states, kinetics of bond formation
between attached structures, effect of molecular environment on receptor
efficiency and behaviour of multivalent attachment, (ii) to compare results
obtain by this and other techniques on a few well defined molecular systems,
and (iii) to discuss the limitations of the flow chamber method. It is
concluded that a new framework may be needed to account for the effective
behaviour of biomolecule association.


title: Vibration-induced climbing of drops

abstract:
  We report an experimental study of liquid drops moving against gravity, when
placed on a vertically vibrating inclined plate, which is partially wetted by
the drop. The frequency of vibrations ranges from 30 to 200 Hz, and, above a
threshold in vibration acceleration, drops experience an upward motion. We
attribute this surprising motion to the deformations of the drop, as a
consequence of an up or down symmetry breaking induced by the presence of the
substrate. We relate the direction of motion to contact angle measurements.
This phenomenon can be used to move a drop along an arbitrary path in a plane,
without special surface treatments or localized forcing.


title: Materialized View Selection by Query Clustering in XML Data Warehouses

abstract:
  XML data warehouses form an interesting basis for decision-support
applications that exploit complex data. However, native XML database management
systems currently bear limited performances and it is necessary to design
strategies to optimize them. In this paper, we propose an automatic strategy
for the selection of XML materialized views that exploits a data mining
technique, more precisely the clustering of the query workload. To validate our
strategy, we implemented an XML warehouse modeled along the XCube
specifications. We executed a workload of XQuery decision-support queries on
this warehouse, with and without using our strategy. Our experimental results
demonstrate its efficiency, even when queries are complex.


title:
Stabilized Kuramoto-Sivashinsky equation: A useful model for secondary
  instabilities and related dynamics of experimental one-dimensional cellular
  flows

abstract:
  We report numerical simulations of one-dimensional cellular solutions of the
stabilized Kuramoto-Sivashinsky equation. This equation offers a range of
generic behavior in pattern-forming instabilities of moving interfaces, such as
a host of secondary instabilities or transition toward disorder. We compare
some of these collective behaviors to those observed in experiments. In
particular, destabilization scenarios of bifurcated states are studied in a
spatially semi-extended situation, which is common in realistic patterns, but
has been barely explored so far.


title: Dynamic index selection in data warehouses

abstract:
  Analytical queries defined on data warehouses are complex and use several
join operations that are very costly, especially when run on very large data
volumes. To improve response times, data warehouse administrators casually use
indexing techniques. This task is nevertheless complex and fastidious. In this
paper, we present an automatic, dynamic index selection method for data
warehouses that is based on incremental frequent itemset mining from a given
query workload. The main advantage of this approach is that it helps update the
set of selected indexes when workload evolves instead of recreating it from
scratch. Preliminary experimental results illustrate the efficiency of this
approach, both in terms of performance enhancement and overhead.


title:
Highly transparent superconducting - normal junctions in a homogeneous
  superconductor induced by local fields of magnetic domains

abstract:
  Using the highly inhomogeneous fields of a magnetic substrate, tunable
junctions between superconducting and normal state regions were created inside
a thin film superconductor. The investigation of these junctions, created in
the same material, gave evidence for the occurrence of Andreev reflection,
indicating the high transparency of interfaces between superconducting and
normal state regions. For the realization of this study, a ferromagnet with
magnetic stripe domains was used as a substrate, on top of which a
superconducting transport bridge was prepared perpendicular to the underlying
domains. The particular choice of materials allowed to restrict the nucleation
of superconductivity to regions above either reverse-domains or domain walls.
Moreover, due to the specific design of the sample, transport currents in the
superconductor passed through a sequence of normal and superconducting regions.


title:
High-probability quantum state transfer among nodes of an open XXZ spin
  chain

abstract:
  This paper concerns the problem of the high probability state transfer among
$2^s$ symmetrically placed nodes of the $N$-nodes spins 1/2 chain with the
  ${XXZ}$ Hamiltonian. We consider examples with $(N,s)=(4,4)$, $(N,s)=(6,4)$
and $(N,s)=(8,8)$.


title:
Persistence, extinction and spatio-temporal synchronization of SIRS
  cellular automata models

abstract:
  Spatially explicit models have been widely used in today's mathematical
ecology and epidemiology to study persistence and extinction of populations as
well as their spatial patterns. Here we extend the earlier work--static
dispersal between neighbouring individuals to mobility of individuals as well
as multi-patches environment. As is commonly found, the basic reproductive
ratio is maximized for the evolutionary stable strategy (ESS) on diseases'
persistence in mean-field theory. This has important implications, as it
implies that for a wide range of parameters that infection rate will tend
maximum. This is opposite with present results obtained in spatial explicit
models that infection rate is limited by upper bound. We observe the emergence
of trade-offs of extinction and persistence on the parameters of the infection
period and infection rate and show the extinction time having a linear
relationship with respect to system size. We further find that the higher
mobility can pronouncedly promote the persistence of spread of epidemics, i.e.,
the phase transition occurs from extinction domain to persistence domain, and
the spirals' wavelength increases as the mobility increasing and ultimately, it
will saturate at a certain value. Furthermore, for multi-patches case, we find
that the lower coupling strength leads to anti-phase oscillation of infected
fraction, while higher coupling strength corresponds to in-phase oscillation.

categories: q-bio.PE nlin.CG nlin.PS physics.soc-ph q-bio.OT


title: Nonequilibrium Cotunneling through a Three-Level Quantum Dot

abstract:
  We calculate the nonlinear cotunneling conductance through a quantum dot with
3 electrons occupying the three highest lying energy levels. Starting from a
3-orbital Anderson model, we apply a generalized Schrieffer-Wolff
transformation to derive an effective Kondo model for the system. Within this
model we calculate the nonequilibrium occupation numbers and the corresponding
cotunneling current to leading order in the exchange couplings. We identify the
inelastic cotunneling thresholds and their splittings with applied magnetic
field, and make a qualitative comparison to recent experimental data on carbon
nanotube and InAs quantum-wire quantum dots. Further predictions of the model
like cascade resonances and a magnetic-field dependence of the orbital level
splitting are not yet observed but within reach of recent experimental work on
carbon nanotube and InAs nanowire quantum dots.


title: The contact binary GSC 04778-00152 with a visual companion

abstract:
  Photometric and spectroscopic observations of the unstudied 12th-magnitude
eclipsing binary GSC 04778-00152 are presented. We report the discovery of a
visual companion about 1 mag fainter and 2 arcsec away from the binary. By
subtracting the light contribution of the visual companion, we obtain the UBVRI
light curves of the binary system alone. The shape of the light curve indicates
that GSC 04778-00152 is an A-type W UMa contact binary. From light-curve
modeling, we derive parameters of the binary system.


title: Knowledge and Metadata Integration for Warehousing Complex Data

abstract:
  With the ever-growing availability of so-called complex data, especially on
the Web, decision-support systems such as data warehouses must store and
process data that are not only numerical or symbolic. Warehousing and analyzing
such data requires the joint exploitation of metadata and domain-related
knowledge, which must thereby be integrated. In this paper, we survey the types
of knowledge and metadata that are needed for managing complex data, discuss
the issue of knowledge and metadata integration, and propose a CWM-compliant
integration solution that we incorporate into an XML complex data warehousing
framework we previously designed.


title: Mass Distribution, Rotation Curves and Gravity Theories

abstract:
  {Comparison of mass density profiles of galaxies of varying sizes based on
some gravity theories from observed galaxy rotation curves and assessing the
need for dark matter.} We present an analysis of the rotation curves of five
galaxies of varying galactic radii: NGC6822 (4.8 kpc), Large Magellanic Cloud
(9 kpc), The Milky Way (17 kpc), NGC3198 (30 kpc) and UGC9133 (102.5 kpc). The
mass and mass density profiles of these galaxies have been computed using the
scientific computing s/w package MATLAB taking the already available velocity
profiles of the galaxies as the input, and without considering any Dark Matter
contribution. We have plotted these profiles after computing them according to
three different theories of gravity (and dynamics): Newtonian (black line),
Modified Newtonian Dynamics (MoND) (green line) and Vacuum Modified Gravity
(red line). We also consider how the profile due to the Newtonian theory would
modify if we take into account a small negative value of the Cosmological
Constant (5 x 10^-56 cm^-2 from theory) (blue line). Comparing these mass and
mass density profiles, we try to form an idea regarding what could be a
realistic theory of gravity and whether we need Dark Matter to explain the
results. Keywords : disk galaxy rotation curves, galaxy mass, mass density
profile, dark matter, Newtonian theory, MoND, Vacuum Modified Gravity, negative
cosmological constant


title: The GL(2) McKay Correspondence

abstract:
  In this paper we show that for any affine complete rational surface
singularity there is a correspondence between the dual graph of the minimal
resolution and the quiver of the endomorphism ring of the special CM modules.
We thus call such an algebra the reconstruction algebra. As a consequence the
derived category of the minimal resolution is equivalent to the derived
category of an algebra whose quiver is determined by the dual graph. Also, for
any finite subgroup G of GL(2,C), it means that the endomorphism ring of the
special CM C[[x,y]]^G modules can be used to build the dual graph of the
minimal resolution of C^2/G, extending McKay's observation for finite subgroups
of SL(2,C) to all finite subgroups of GL(2,C).


title:
Understanding the edge effect in TASEP with mean-field theoretic
  approaches

abstract:
  We study a totally asymmetric simple exclusion process (TASEP) with one
defect site, hopping rate $q<1$, near the system boundary. Regarding our system
as a pair of uniform TASEP's coupled through the defect, we study various
methods to match a \emph{finite} TASEP and an \emph{infinite} one across a
common boundary. Several approximation schemes are investigated. Utilizing the
finite segment mean-field (FSMF) method, we set up a framework for computing
the steady state current $J$ as a function of the entry rate $% \alpha $ and
$q$. For the case where the defect is located at the entry site, we obtain an
analytical expression for $J(\alpha, q) $ which is in good agreement with Monte
Carlo simulation results. When the defect is located deeper in the bulk, we
refined the scheme of MacDonald, et.al. [Biopolymers, \textbf{6}, 1 (1968)] and
find reasonably good fits to the density profiles before the defect site. We
discuss the strengths and limitations of each method, as well as possible
avenues for further studies.


title: Chaotic systems in complex phase space

abstract:
  This paper examines numerically the complex classical trajectories of the
kicked rotor and the double pendulum. Both of these systems exhibit a
transition to chaos, and this feature is studied in complex phase space.
Additionally, it is shown that the short-time and long-time behaviors of these
two PT-symmetric dynamical models in complex phase space exhibit strong
qualitative similarities.

categories: hep-th cond-mat.dis-nn math-ph math.MP nlin.CD


title:
Dark Matter Gravitational Clustering With a Long-Range Scalar
  Interaction

abstract:
  We explore the possibility of improving the $\Lambda$CDM model at megaparsec
scales by introducing a scalar interaction which increases the mutual
gravitational attraction of dark matter particles. Using N-body simulations, we
study the spatial distribution of dark matter particles and halos. We measure
the effect of modifications in the Newton's gravity on properties of the
two-point correlation function, the dark matter power spectrum, the cumulative
halo mass function and density probability distribution functions. The results
look promising: the scalar interactions produce desirable features at
megaparsec scales without spoiling the $\Lambda$CDM successes at larger scales.


title:
ADS/CFT Applied To Vector Meson Emission From A Heavy Accelerated
  Nucleus

abstract:
  We consider a classical source, moving on the 4-D boundary of a 5-D ADS
space, that is coupled to quantum fields residing in the bulk.
Bremsstrahlung-like radiation of the corresponding quanta is shown to occur and
the S-matrix is derived assuming that the source is sufficiently massive so
that recoil effects are negligible. As an illustrative example, using the ADS
hard-wall model, we consider vector mesons coupled to a heavy nucleus that is
moved around at high speed in an accelerator ring. The meson radiation rate is
found to be finite but small. Much higher accelerations, such as when a pair of
heavy ions suffer an ultra peripheral collision, cause substantial emission of
various excited vector mesons. Predictions are made for the spectrum of this
radiation. A comparison is made against existing photon-pomeron fusion
calculations for the transverse momentum spectra of rho mesons. These have the
same overall shape as the recently measured transverse momentum distributions
at RHIC.


title: Learning of correlated patterns by simple perceptrons

abstract:
  Learning behavior of simple perceptrons is analyzed for a teacher-student
scenario in which output labels are provided by a teacher network for a set of
possibly correlated input patterns, and such that teacher and student networks
are of the same type. Our main concern is the effect of statistical
correlations among the input patterns on learning performance. For this
purpose, we extend to the teacher-student scenario a methodology for analyzing
randomly labeled patterns recently developed in {\em J. Phys. A: Math. Theor.}
{\bf 41}, 324013 (2008). This methodology is used for analyzing situations in
which orthogonality of the input patterns is enhanced in order to optimize the
learning performance.


title:
Convective hydrocodes for radial stellar pulsation. Physical and
  numerical formulation

abstract:
  In this paper we describe our convective hydrocodes for radial stellar
pulsation. We adopt the Kuhfuss (1986) model of convection, reformulated for
the use in stellar pulsation hydrocodes. Physical as well as numerical
assumptions of the code are described in detail. Described tests show, that our
models are numerically robust and reproduce basic observational constraints.
  We discuss the effects of different treatment of some quantities in other
pulsation hydrocodes. Our most important finding concerns the treatment of the
turbulent source function in convectively stable regions. In our code we allow
for negative values of source function in convectively stable zones, which
reflects negative buoyancy. However, some authors restrict the source term to
non-negative values. We show that this assumption leads to very high turbulent
energies in convectively stable regions. The effect looks like overshooting,
but it is not, because turbulence is generated by pulsations. Also, turbulent
elements do not carry kinetic nor thermal energy, into convectively stable
layers. The range of this artificial overshooting (as we shall call it) is as
large as 6 local pressure scale heights, leading to unphysical internal damping
through the eddy-viscous forces, in deep, convectively stable parts of the
star.


title: Intersection Graphs of Pseudosegments: Chordal Graphs

abstract:
  We investigate which chordal graphs have a representation as intersection
graphs of pseudosegments. For positive we have a construction which shows that
all chordal graphs that can be represented as intersection graph of subpaths on
a tree are pseudosegment intersection graphs. We then study the limits of
representability. We describe a family of intersection graphs of substars of a
star which is not representable as intersection graph of pseudosegments. The
degree of the substars in this example, however, has to get large. A more
intricate analysis involving a Ramsey argument shows that even in the class of
intersection graphs of substars of degree three of a star there are graphs that
are not representable as intersection graph of pseudosegments.
  Motivated by representability questions for chordal graphs we consider how
many combinatorially different k-segments, i.e., curves crossing k distinct
lines, an arrangement of n pseudolines can host. We show that for fixed k this
number is in O(n^2). This result is based on a k-zone theorem for arrangements
of pseudolines that should be of independent interest.


title: A Join Index for XML Data Warehouses

abstract:
  XML data warehouses form an interesting basis for decision-support
applications that exploit complex data. However, native-XML database management
systems (DBMSs) currently bear limited performances and it is necessary to
research for ways to optimize them. In this paper, we propose a new join index
that is specifically adapted to the multidimensional architecture of XML
warehouses. It eliminates join operations while preserving the information
contained in the original warehouse. A theoretical study and experimental
results demonstrate the efficiency of our join index. They also show that
native XML DBMSs can compete with XML-compatible, relational DBMSs when
warehousing and analyzing XML data.


title: Quintessential Kination and Thermal Production of SUSY e-WIMPs

abstract:
  The impact of a kination-dominated phase generated by a quintessential
exponential model on the thermal abundance of Supersymmetric (SUSY) extremely
Weekly Interacting Massive Particles (e-WIMPs) is investigated. For values of
the quintessential energy-density parameter on the eve of nucleosynthesis close
to its upper bound, we find that: (i) the gravitino constraint is totally
evaded for unstable gravitinos; (ii) the thermal abundance of stable gravitinos
is not sufficient to account for the cold dark matter of the universe; (iii)
the thermal abundance of axinos can satisfy the cold dark matter constraint for
values of the initial (``reheating'') temperature well above those required in
the standard cosmology.


title: General Lp affine isoperimetric inequalities

abstract:
  Sharp Lp affine isoperimetric inequalities are established for the entire
class of Lp projection bodies and the entire class of Lp centroid bodies. These
new inequalities strengthen the Lp Petty projection and the Lp Busemann--Petty
centroid inequality.


title:
Excess noise depletion of a Bose-Einstein condensate in an optical
  cavity

abstract:
  Quantum fluctuations of a cavity field coupled into the motion of ultracold
bosons can be strongly amplified by a mechanism analogous to the Petermann
excess noise factor in lasers with unstable cavities. For a Bose-Einstein
condensate in a stable optical resonator, the excess noise effect amounts to a
significant depletion on long timescales.


title: Affine Models

abstract:
  Affine term structure models have gained significant attention in the finance
literature, mainly due to their analytical tractability and statistical
flexibility. The aim of this article is to present both theoretical foundations
as well as empirical aspects of the affine model class. Starting from the
original one-factor short-rate models of Vasi\v{c}ek and Cox \emph{et al,} we
provide an overview of the properties of regular affine processes and explain
their relationship to affine term structure models. Methods for securities
pricing and for parameter estimation are also discussed, demonstrating how the
analytical tractability of affine models can be exploited for practical
purposes.


title: Double-mode classical Cepheid models - revisited

abstract:
  For many years modeling of double-mode pulsation of classical pulsators was a
challenging problem. Inclusion of turbulent convection into pulsation
hydrocodes finally led to stable double-mode models. However, it was never
analysed, which factor of turbulent convection is crucial. We show that the
double-mode behaviour displayed in the computed models results from incorrect
assumptions adopted in some of the pulsation hydrocodes, namely from the
neglect of buoyant forces in convectively stable layers. This leads to
significant turbulent energies and consequently to strong eddy-viscous damping
in deep, convectively stable layers of the model. Resulting differential
reduction of fundamental and first overtone amplitudes favours the occurrence
of double-mode pulsation. Once buoyant forces in convectively stable regions
are taken into account (as they should), no stable double-mode behaviour is
found. The problem of modeling double-mode behaviour of classical pulsators
remains open.


title:
Thermodynamic behavior of the XXZ Heisenberg s=1/2 chain around the
  factorizing magnetic field

abstract:
  We have investigated the zero and finite temperature behaviors of the
anisotropic antiferromagnetic Heisenberg XXZ spin-1/2 chain in the presence of
a transverse magnetic field (h). The attention is concentrated on an interval
of magnetic field between the factorizing field (h_f) and the critical one
(h_c). The model presents a spin-flop phase for 0<h<h_f with an energy scale
which is defined by the long range antiferromagnetic order while it undergoes
an entanglement phase transition at h=h_f. The entanglement estimators clearly
show that the entanglement is lost exactly at h=h_f which justifies different
quantum correlations on both sides of the factorizing field. As a consequence
of zero entanglement (at h=h_f) the ground state is known exactly as a product
of single particle states which is the starting point for initiating a spin
wave theory. The linear spin wave theory is implemented to obtain the specific
heat and thermal entanglement of the model in the interested region. A double
peak structure is found in the specific heat around h=h_f which manifests the
existence of two energy scales in the system as a result of two competing
orders before the critical point. These results are confirmed by the low
temperature Lanczos data which we have computed.


title: Searching for Pop III stars and galaxies at high redshift

abstract:
  We review the expected properties of Pop III and very metal-poor starburst
and the behaviour the Lyman-alpha and HeII 1640 emission lines, which are most
likely the best/easiest signatures to single out such objects. Existing claims
of Pop III signatures in distant galaxies are critically examined, and the
searches for HeII 1640 emission at high redshift are summarised. Finally, we
briefly summarise ongoing and future deep observations at z>6 aiming in
particular at detecting the sources of cosmic reionisation as well as
primeval/Pop III galaxies.


title: Distributing Labels on Infinite Trees

abstract:
  Sturmian words are infinite binary words with many equivalent definitions:
They have a minimal factor complexity among all aperiodic sequences; they are
balanced sequences (the labels 0 and 1 are as evenly distributed as possible)
and they can be constructed using a mechanical definition. All this properties
make them good candidates for being extremal points in scheduling problems over
two processors. In this paper, we consider the problem of generalizing Sturmian
words to trees. The problem is to evenly distribute labels 0 and 1 over
infinite trees. We show that (strongly) balanced trees exist and can also be
constructed using a mechanical process as long as the tree is irrational. Such
trees also have a minimal factor complexity. Therefore they bring the hope that
extremal scheduling properties of Sturmian words can be extended to such trees,
as least partially. Such possible extensions are illustrated by one such
example.


title: Momentum deficit in quantum glasses

abstract:
  Using the concept of tunneling two level systems we explain the reduction of
rotational inertia of disordered solid 4He observed in the torsional oscillator
experiments. The key point is a peculiar quantum phenomenon of momentum deficit
for two level systems in moving solids. We show that an unusual state which is
essentially different from both normal and superfluid solid states can be
realized in quantum glasses. This state is characterized by reduced rotational
inertia in oscillator experiments, by absence of a superflow, and by normal
behavior in steady rotation.


title:
On a generalization of the support problem of Erdos and its analogues
  for abelian varieties and K-theory

abstract:
  In this paper we consider certain local-global principles for Mordell-Weil
type groups over number fields like S-units, abelian varieties and algebraic
K-theory groups


title: g-Natural metrics of constant sectional curvature

abstract:
  We prove that the tangent bundle endowed with a g-natural metrics has
constant sectional curvature if and only if it is flat, and then we give a
characterization of flat g-natural metrics on tangent bundles.


title: Dusty Cometary Globules in W5

abstract:
  We report the discovery of four dusty cometary tails around low mass stars in
two young clusters belonging to the W5 star forming region. Fits to the
observed emission profiles from 24 micron observations with the Spitzer Space
Telescope give tail lifetimes < 30 Myr, but more likely < 5 Myr. This result
suggests that the cometary phase is a short lived phenomenon, occurring after
photoevaporation by a nearby O star has removed gas from the outer disk of a
young low mass star (see also Balog et al. 2006; Balog et al. 2008).


title:
The SU(2) X U(1) Electroweak Model based on the Nonlinearly Realized
  Gauge Group. II. Functional Equations and the Weak Power-Counting

abstract:
  In the present paper, that is the second part devoted to the construction of
an electroweak model based on a nonlinear realization of the gauge group SU(2)
X U(1), we study the tree-level vertex functional with all the sources
necessary for the functional formulation of the relevant symmetries (Local
Functional Equation, Slavnov-Taylor identity, Landau Gauge Equation) and for
the symmetric removal of the divergences. The Weak Power Counting criterion is
proven in the presence of the novel sources. The local invariant solutions of
the functional equations are constructed in order to represent the counterterms
for the one-loop subtractions. The bleaching technique is fully extended to the
fermion sector. The neutral sector of the vector mesons is analyzed in detail
in order to identify the physical fields for the photon and the Z boson. The
identities necessary for the decoupling of the unphysical modes are fully
analyzed. These latter results are crucially bound to the Landau gauge used
throughout the paper.


title:
The homoclinic and heteroclinic C*-algebras of a generalized
  one-dimensional solenoid

abstract:
  It is shown that the heteroclinic and homoclinic algebras of a generalized
one-dimensional solenoid are simple AH-algebras of real rank zero with no
dimension growth and a unique trace. In the orientable case they are
AT-algebras, and in the non-orientable case they have two-torsion both in K_1
and K_0.


title: Koshino-Taylor effect in graphene

abstract:
  We discuss the phonon-assisted scattering of electrons by defects, i.e., the
so-called Koshino-Taylor effect, in graphene. The two-dimensional character of
graphene implies that the strength of the Koshino-Taylor effect can be
considerably larger than in ordinary metals. We show that at finite
temperatures the defect-induced resistivity formally diverges in the
thermodynamic limit, having a non-analytic $T\ln T$ component when finite size
effects are taken into account.


title: The Hubble parameters in the D-brane models

abstract:
  We consider the DBI action for the D-branes with the dynamic embeddings in
the background produced by p-branes. For the D-brane with the special topology
we obtain two Hublle parameters on this brane. The condition for the equality
of these parameters is analyzed. In the special case a mass and a charge of the
background p-branes are derived from this condition.


title:
QCD Sum Rules and 1/$N_c$ expansion: On the low energy dominance and
  separation of scattering backgrounds

abstract:
  In multiquark correlator analyses with 1/Nc classifications, it is possible
to separate the scattering background and to justify the factorization of
condensates, which allows us to achieve an isolated peak saturation in the QCD
sum rules for multiquark currents. Then we can extract leading Nc properties of
the ground state. An application to the sigma meson is demonstrated.


title: Optimal geometry for efficient loading of an optical dipole trap

abstract:
  One important factor which determines efficiency of loading cold atoms into
an optical dipole trap from a magneto-optical trap is the distance between the
trap centers. By studying this efficiency for various optical trap depths
(2--110 mK) we find that for optimum dipole trap loading, longitudinal
displacements up to 15 mm are necessary. An explanation for this observation is
presented and compared with other work and a simple analytical formula is
derived for the optimum distance between the trap centers.


title: Rough Volterra equations 1: the algebraic integration setting

abstract:
  We define and solve Volterra equations driven by an irregular signal, by
means of a variant of the rough path theory called algebraic integration. In
the Young case, that is for a driving signal with H\"older exponent greater
than 1/2, we obtain a global solution, and are able to handle the case of a
singular Volterra coefficient. In case of a driving signal with H\"older
exponent in (1/3,1/2], we get a local existence and uniqueness theorem. The
results are easily applied to the fractional Brownian motion with Hurst
coefficient H>1/3.


title:
Charged Rotating Kaluza-Klein Black Holes Generated by G2(2)
  Transformation

abstract:
  Applying the G_{2(2)} generating technique for minimal D=5 supergravity to
the Rasheed black hole solution, we present a new rotating charged Kaluza-Klein
black hole solution to the five-dimensional Einstein-Maxwell-Chern-Simons
equations. At infinity, our solution behaves as a four-dimensional flat
spacetime with a compact extra dimension and hence describes a Kaluza-Klein
black hole. In particlar, the extreme solution is non-supersymmetric, which is
contrast to a static case. Our solution has the limits to the asymptotically
flat charged rotating black hole solution and a new charged rotating black
string solution.


title: Herwig++ Status Report

abstract:
  Herwig++ is the successor of the event generator HERWIG. In its present
version 2.2.1 it provides a program for full LHC event generation which is
superior to the previous program in many respects. We briefly summarize its
features and describe present work and some future plans.


title: Exact models for trimerization and tetramerization in spin chains

abstract:
  We present exact models for an antiferromagnetic S=1 spin chain describing
trimerization as well as for an antiferromagnetic S=3/2 spin chain describing
tetramerization. These models can be seen as generalizations of the
Majumdar-Ghosh model. For both models, we provide a local Hamiltonian and its
exact three- or four-fold degenerate ground state wavefunctions, respectively.
We numerically confirm the validity of both models using exact diagonalization
and discuss the low lying excitations.


title:
Signature of multiple glassy states in micellar nanoparticle-polymer
  composites

abstract:
  We present results of temperature dependent measurements of dynamics of
micellar nanoparticle - polymer composites of fixed volume fraction and
variable polymer chain grafting density. For nanoparticles with lower grafting
density we observe dynamically arrested state at low temperatures corresponding
to an attractive glass while at high temperature the same system shows
relaxation typical of a repulsive glass. For higher grafting density, the low
temperature dynamics resembles more of a gel which crosses over to a repulsive
glass at high temperature. Possible reasons for such fascinating dynamical
transitions is delineated.


title:
Ferromagnetic ordering in dilute magnetic dielectrics with and without
  free carriers

abstract:
  The state of art in the theoretical and experimental studies of transition
metal doped oxides (dilute magnetic dielectrics) is reviewed. The available
data show that the generic non-equilibrium state of oxide films doped with
magnetic impurities may either favor ferromagnetism with high Curie temperature
or result in highly inhomogeneous state without long-range magnetic order. In
both case concomitant defects (vacancies, interstitial ions play crucial part.


title: Ab initio compressive phase retrieval

abstract:
  Any object on earth has two fundamental properties: it is finite, and it is
made of atoms. Structural information about an object can be obtained from
diffraction amplitude measurements that account for either one of these traits.
Nyquist-sampling of the Fourier amplitudes is sufficient to image single
particles of finite size at any resolution. Atomic resolution data is routinely
used to image molecules replicated in a crystal structure. Here we report an
algorithm that requires neither information, but uses the fact that an image of
a natural object is compressible. Intended applications include tomographic
diffractive imaging, crystallography, powder diffraction, small angle x-ray
scattering and random Fourier amplitude measurements.


title:
Nonlinear Dynamics of Bose-Einstein Condensates with Long-Range
  Interactions

abstract:
  The motto of this paper is: Let's face Bose-Einstein condensation through
nonlinear dynamics. We do this by choosing variational forms of the condensate
wave functions (of given symmetry classes), which convert the Bose-Einstein
condensates via the time-dependent Gross-Pitaevskii equation into Hamiltonian
systems that can be studied using the methods of nonlinear dynamics. We
consider in particular cold quantum gases where long-range interactions between
the neutral atoms are present, in addition to the conventional short-range
contact interaction, viz. gravity-like interactions, and dipole-dipole
interactions. The results obtained serve as a useful guide in the search for
nonlinear dynamics effects in numerically exact quantum calculations for
Bose-Einstein condensates. A main result is the prediction of the existence of
stable islands as well as chaotic regions for excited states of dipolar
condensates, which could be checked experimentally.


title:
Modeling of the evolution of dielectric loss with processing temperature
  in ferroelectric and dielectric thin oxide films

abstract:
  It was experimentally found that the evolution of dielectric loss with
processing temperature displays a common trend in ferroelectric and dielectric
thin oxide films: firstly an increase and then a decrease in dielectric loss
when the processing temperature is gradually raised. Such a dielectric response
of ferroelectric/dielectric thin films has been theoretically addressed in this
work. We propose that at the initial stage of the crystallization process in
thin films, the transformation from amorphous to crystalline phase should
increase substantially the dielectric loss; then, with further increase in the
processing temperature, the coalescent growth of small crystalline grains into
big ones could be helpful in reducing the dielectric loss by lowering grain
boundary densities. The obtained experimental data for (Ba,Sr)TiO3 thin films
with 500 nm in thickness were analyzed in terms of the model developed and
shown to be in a reasonable agreement with the theoretical results.


title: Superconductivity induced by Ni doping in BaFe$_2$As$_2$

abstract:
  A series of 122 phase BaFe$_{2-x}$Ni$_x$As$_2$ ($x$ = 0, 0.055, 0.096, 0.18,
0.23) single crystals were grown by self flux method and a dome-like Ni doping
dependence of superconducting transition temperature is discovered. The
transition temperature $T_c^{on}$ reaches a maximum of 20.5 K at $x$ = 0.096,
and it drops to below 4 K as $x$ $\geq$ 0.23. The negative thermopower in the
normal state indicates that electron-like charge carrier indeed dominates in
this system. This Ni-doped system provides another example of superconductivity
induced by electron doping in the 122 phase.


title:
Maximum memory capacity on neural networks with short-term depression
  and facilitation

abstract:
  In this work we study, analytically and employing Monte Carlo simulations,
the influence of the competition between several activity-dependent synaptic
processes, such as short-term synaptic facilitation and depression, on the
maximum memory storage capacity in a neural network. In contrast with the case
of synaptic depression, which drastically reduces the capacity of the network
to store and retrieve "static" activity patterns, synaptic facilitation
enhances the storage capacity in different contexts. In particular, we found
optimal values of the relevant synaptic parameters (such as the
neurotransmitter release probability or the characteristic facilitation time
constant) for which the storage capacity can be maximal and similar to the one
obtained with static synapses, that is, without activity-dependent processes.
We conclude that depressing synapses with a certain level of facilitation allow
to recover the good retrieval properties of networks with static synapses while
maintaining the nonlinear characteristics of dynamic synapses, convenient for
information processing and coding.


title: B-L mediated SUSY breaking with radiative B-L symmetry breaking

abstract:
  We explore a mechanism of radiative B-L symmetry breaking in analogous to the
radiative electroweak symmetry breaking. The breaking scale of B-L symmetry is
related to the neutrino masses through the see-saw mechanism. Once we
incorporate the U(1)(B-L) gauge symmetry in SUSY models, the U(1)(B-L) gaugino
appears, and it can mediate the SUSY breaking (Z-prime mediated SUSY breaking)
at around the scale of 10^6 GeV. Then we find a links between the neutrino mass
(more precisly the see-saw or B-L scale of order 10^6 GeV) and the Z-prime
mediated SUSY breaking scale. It is also very interesting that the gluino at
the weak scale becomes relatively light, and almost compressed mass spectra for
the gaugino sector can be realized in this scenario, which is very interesting
in scope of the LHC.


title:
Non-universal gaugino and scalar masses, hadronically quiet trileptons
  and the Large Hadron Collider

abstract:
  We investigate the parameter space of the minimal supersymmetric Standard
Model (MSSM) where the gluino and squark masses are much above 1 TeV but the
remaining part of the sparticle spectrum is accessible to the Large Hadron
Collider at CERN. After pointing out that such a scenario may constitute an
important benchmark of gaugino/scalar non-universality, we find that
hadronically quiet trileptons are rather useful signals for it. Regions of the
parameter space, where the signal is likely to be appreciable, are identified
through a detailed scan. The advantage of hadronically quiet trileptons over
other types of signals is demonstrated.


title: Dirac Born Infeld (DBI) Cosmic Strings

abstract:
  Motivated by brane physics, we consider the non-linear Dirac-Born-Infeld
(DBI) extension of the Abelian-Higgs model and study the corresponding cosmic
string configurations. The model is defined by a potential term, assumed to be
of the mexican hat form, and a DBI action for the kinetic terms. We show that
it is a continuous deformation of the Abelian-Higgs model, with a single
deformation parameter depending on a dimensionless combination of the scalar
coupling constant, the vacuum expectation value of the scalar field at
infinity, and the brane tension. By means of numerical calculations, we
investigate the profiles of the corresponding DBI-cosmic strings and prove that
they have a core which is narrower than that of Abelian-Higgs strings. We also
show that the corresponding action is smaller than in the standard case
suggesting that their formation could be favoured in brane models. Moreover we
show that the DBI-cosmic string solutions are non-pathological everywhere in
parameter space. Finally, in the limit in which the DBI model reduces to the
Bogomolnyi-Prasad-Sommerfield (BPS) Abelian-Higgs model, we find that DBI
cosmic strings are no longer BPS: rather they have positive binding energy. We
thus argue that, when they meet, two DBI strings will not bind with the
corresponding formation of a junction, and hence that a network of DBI strings
is likely to behave as a network of standard cosmic strings.


title: SO and USp Kahler and Hyper-Kahler Quotients and Lumps

abstract:
  We study non-linear sigma models whose target spaces are the Higgs phases of
supersymmetric SO and USp gauge theories by using the Kahler and hyper-Kahler
quotient constructions. We obtain the explicit Kahler potentials and develop an
expansion formula to make use of the obtained potentials from which we also
calculate the curvatures of the manifolds. The 1/2 BPS lumps in the U(1) x SO
and U(1) x USp Kahler quotients and their effective descriptions are also
studied. In this connection, a general relation between moduli spaces of
vortices and lumps is discussed. We find a new singular limit of the lumps with
non-vanishing sizes in addition to the ordinary small lump singularity. The
former is due to the existence of singular submanifolds in the target spaces.


title: Two dimensional XXZ-Ising model on square-hexagon lattice

abstract:
  We study a two dimensional XXZ-Ising on square-hexagon (4-6) lattice with
spin-1/2. The phase diagram of the ground state energy is discussed, shown two
different ferrimagnetic states and two type of antiferromagnetic states, beside
of a ferromagnetic state. To solve this model, it could be mapped into the
eight-vertex model with union jack interaction term. Imposing exact solution
condition we find the region where the XXZ-Ising model on 4-6 lattice have
exact solutions with one free parameter, for symmetric eight-vertex model
condition. In this sense we explore the properties of the system and analyze
the competition of the interaction parameters providing the region where it has
an exact solution. However the present model does not satisfy the \textit{free
fermion} condition, unless for a trivial situation. Even so we are able to
discuss their critical points region, when the exactly solvable condition is
ignored.


title: The Imperial IRAS-FSC Redshift Catalogue (IIFSCz)

abstract:
  We present a new catalogue, the Imperial IRAS-FSC Redshift Catalogue
(IIFSCz), of 60,303 galaxies selected at 60 micron from the IRAS Faint Source
Catalogue (FSC). The IIFSCz consists of accurate position, optical,
near-infrared and/or radio identifications, spectroscopic redshift (if
available) or photometric redshift (if possible), predicted far-infrared (FIR)
and submillimetre (submm) fluxes ranging from 12 to 1380 micron based upon the
best-fit infrared template. About 55% of the galaxies in the IIFSCz have
spectroscopic redshifts and a further 20% have photometric redshifts obtained
through either the training set or the template-fitting method. For S(60)>0.36
Jy, the 90% completeness limit of the FSC, 90% of the sources have either
spectroscopic or photometric redshifts. Scientific applications of the IIFSCz
include validation of current and forthcoming infrared and submm/mm surveys
such as AKARI, Planck and Herschel, follow-up studies of rare source
populations, large-scale structure and galaxy bias, local multiwavelength
luminosity functions and source counts. The catalogue is publicly available
from http://astro.imperial.ac.uk/~mrr/fss/


title: Lecture notes: Semidefinite programs and harmonic analysis

abstract:
  Lecture notes for the tutorial at the workshop HPOPT 2008 - 10th
International Workshop on High Performance Optimization Techniques (Algebraic
Structure in Semidefinite Programming), June 11th to 13th, 2008, Tilburg
University, The Netherlands.


title: Duality in a special class of submanifolds and Frobenius manifolds

abstract:
  We prove a duality principle for a special class of submanifolds in
pseudo-Euclidean spaces. This class of submanifolds with potential of normals
is introduced in this paper. We prove also, for example, that an arbitrary
Frobenius manifold can be realized as a certain flat submanifold of this very
natural class.

categories: math.DG hep-th math-ph math.AG math.MP nlin.SI


title: Non-degenerate quadratic laminations

abstract:
  We give a combinatorial criterion for a critical diameter to be compatible
with a non-degenerate quadratic lamination.


title: Black holes and non-relativistic quantum systems

abstract:
  We describe black holes in d+3 dimensions, whose thermodynamic properties
correspond to those of a scale invariant non-relativistic d+1 dimensional
quantum system with dynamical exponent z=2. The gravitational model involves a
massive abelian vector field and a scalar field, in addition to the metric. The
energy per particle in the dual theory is $|\mu| d/(d+2)$, exactly as in a
non-interacting Fermi gas, while the ratio of shear viscosity to entropy
density is $\hbar/4\pi$.


title: Structure on the set of closure operations of a commutative ring

abstract:
  We investigate the algebraic structure on the set of closure operations of a
ring. We show the set of closure operations is not a monoid under composition
for a discrete valuation ring. Even the set of semiprime operations over a DVR
is not a monoid; however, it is the union of two monoids, one being the left
but not right act of the other. We also determine all semiprime operations over
the ring $K[[t^2, t^3]]$.


title: Cosmology without inflation

abstract:
  We propose a new cosmological paradigm in which our observed expanding phase
is originated from an initially large contracting Universe that subsequently
experienced a bounce. This category of models, being geodesically complete, is
non-singular and horizon-free, and can be made to prevent any relevant scale to
ever have been smaller than the Planck length. In this scenario, one can find
new ways to solve the standard cosmological puzzles. One can also obtain scale
invariant spectra for both scalar and tensor perturbations: this will be the
case, for instance, if the contracting Universe is dust-dominated at the time
at which large wavelength perturbations get larger than the curvature scale. We
present a particular example based on a dust fluid classically contracting
model, where a bounce occurs due to quantum effects, in which these features
are explicit.


title: Star Formation in the Trifid Nebula

abstract:
  We have obtained maps of the 1.25mm thermal dust emission and the molecular
gas emission over a region of 20' by 10' arcmin around the Trifid Nebula (M20),
with the IRAM 30m and the CSO telescopes as well as in the mid-infrared
wavelength with ISO and SPITZER. Our survey is sensitive to features down to
N(H2) \sim 10^{22} cm-2 in column density. The cloud material is distributed in
fragmented dense gas filaments (n(H2) \sim 1000 cm-3) with sizes ranging from 1
to 10 pc. A massive filament, WF, with properties typical of Infra Red Dark
Clouds, connects M20 to the W28 supernova remnant. These filaments pre-exist
the formation of the Trifid and were originally self-gravitating. The fragments
produced are very massive (100 Msun or more) and are the progenitors of the
cometary globules observed at the border of the HII region. We could identify
33 cores, 16 of which are currently forming stars. They are usually
gravitationally unbound and have low masses of a few Msun. The densest starless
cores (several 10^5 cm-3) may be the site for the next generation of stars. The
physical gas and dust properties of the cometary globules have been studied in
detail and have been found very similar. They all are forming stars. Several
intermediate-mass protostars have been detected in the cometary globules and in
the deeply embedded cores. Evidence of clustering has been found in the shocked
massive cores TC3-TC4-TC5. M20 is a good example of massive-star forming region
in a turbulent, filamentary molecular cloud. Photoionization appears to play a
minor role in the formation of the cores. The observed fragmentation is well
explained by MHD-driven instabilities and is usually not related to M20. We
propose that the nearby supernova remnant W28 could have triggered the
formation of protostellar clusters in nearby dense cores of the Trifid.


title: Creation of a quantum oscillator by classical control

abstract:
  As a pure quantum state is being approached via linear feedback, and the
occupation number approaches and eventually goes below unity, optimal control
becomes crucial. We obtain theoretically the optimal feedback controller that
minimizes the uncertainty for a general linear measurement process, and show
that even in the absence of classical noise, a pure quantum state is not always
achievable via feedback. For Markovian measurements, the deviation from minimum
Heisenberg Uncertainty is found to be closely related to the extent to which
the device beats the free-mass Standard Quantum Limit for force measurement. We
then specialize to optical Markovian measurements, and demonstrate that a
slight modification to the usual input-output scheme -- either injecting
frequency independent squeezed vacuum or making a homodyne detection at a
non-phase quadrature -- allows controlled states of kilogram-scale mirrors in
future LIGO interferometers to reach occupation numbers significantly below
unity.


title:
Collapse and Revival of Entanglement between Qubits Interacting via a
  Quantum Bus

abstract:
  We study the dynamics of the Jaynes-Cummings Model for two level systems (or
qubits) interacting with a quantized single mode electromagnetic cavity (or
`quantum bus'). We show that there is a time in between the collapse and
revival of Rabi oscillations when the state of the qubit sub-system, $|
\psi\_{attractor} $, is largely independent of its initial state. This
generalizes to many qubits the discovery by Gea-Banacloche for the one qubit
case. The qubits in such `attractor' states are not entangled either with the
field or among themselves, even if they were in the initial state. Subsequently
the entanglement between the qubits revives. Finally, it is argued that the
collapse and revival of entanglement and the persistence of `non-classicality'
is a generic feature of multiple qubits interacting via a `quantum bus'.


title:
Diamond nanoparticles as photoluminescent nanoprobes for biology and
  near-field optics

abstract:
  We present results showing the potential of diamond nanoparticles with size
less than 50 nm as photoluminescent nanoprobes for serving as stable point-like
emitters attached at the tip apex of a near-field optical microscope to achieve
enhanced spatial resolution.


title:
Photometric redshifts as a tool to study the Coma cluster galaxy
  populations

abstract:
  We investigate the Coma cluster galaxy luminosity function (GLF) at faint
magnitudes, in particular in the u* band by applying photometric redshift
techniques applied to deep u*, B, V, R, I images covering a region of ~1deg2 (R
24). Global and local GLFs in the B, V, R and I bands obtained with photometric
redshift selection are consistent with our previous results based on a
statistical background subtraction.
  In the area covered only by the u* image, the GLF was also derived after
applying a statistical background subtraction. The GLF in the u* band shows an
increase of the faint end slope towards the outer regions of the cluster (from
alpha~1 in the cluster center to alpha~2 in the cluster periphery). This could
be explained assuming a short burst of star formation in these galaxies when
entering the cluster.
  The analysis of the multicolor type spatial distribution reveals that late
type galaxies are distributed in clumps in the cluster outskirts, where X-ray
substructures are also detected and where the GLF in the u* band is steeper.


title: Sterile neutrinos in cosmology and how to find them in the lab

abstract:
  A number of observed phenomena in high energy physics and cosmology lack
their resolution within the Standard Model of particle physics. These puzzles
include neutrino oscillations, baryon asymmetry of the universe and existence
of dark matter. We discuss the suggestion that all these problems can be solved
by new physics which exists only below the electroweak scale. The dedicated
experiments that can confirm or rule out this possibility are discussed.


title: Hyperfine structure of Sc@C82 from ESR and DFT

abstract:
  The electron spin g- and hyperfine tensors of the endohedral metallofullerene
Sc@C82 are anisotropic. Using electron spin resonance (ESR) and density
functional theory (DFT), we can relate their principal axes to the coordinate
frame of the molecule, finding that the g-tensor is not axially symmetric. The
Sc bond with the cage is partly covalent and partly ionic. Most of the electron
spin density is distributed around the carbon cage, but 5% is associated with
the scandium d_yz orbital, and this drives the observed anisotropy.


title: Radiative and Collisional Energy Loss, and Photon-Tagged Jets at RHIC

abstract:
  The suppression of single jets at high transverse momenta in a quark-gluon
plasma is studied at RHIC energies, and the additional information provided by
a photon tag is included. The energy loss of hard jets traversing through the
medium is evaluated in the AMY formalism, by consistently taking into account
the contributions from radiative events and from elastic collisions at leading
order in the coupling. The strongly-interacting medium in these collisions is
modelled with (3+1)-dimensional ideal relativistic hydrodynamics. Putting these
ingredients together with a complete set of photon-production processes, we
present a calculation of the nuclear modification of single jets and
photon-tagged jets at RHIC.


title: On von Neumann's Examples of Types

abstract:
  The paper introduces in a new although maybe unusual form the examples of
types provided by J. von Neumann and F.J. Murray in their outstanding papers on
algebraic factorization (1936-1943)pursuing three main aims: speculating about
the physical reasons and motivations that are likely to have been at the origin
of von Neumann's investigation; describing the examples of factors provided by
those authors with the purpose of clarifying the general concepts standing at
the base of the classification of factors into three general types; outlining
the perspective of extending the theory to non--separable Hilbert spaces with
the purpose of suggesting a novel approach to the representation of infinite
systems controlled by external gauge fields.


title: On consistency of determinants on cubic lattices

abstract:
  We propose a modified condition of consistency on cubic lattices for some
special classes of two-dimensional discrete equations and prove that the
discrete nonlinear equations defined by determinants of matrices of orders N >
2 are consistent on cubic lattices in this sense.


title: Early Universe Constraints on Time Variation of Fundamental Constants

abstract:
  We study the time variation of fundamental constants in the early Universe.
Using data from primordial light nuclei abundances, CMB and the 2dFGRS power
spectrum, we put constraints on the time variation of the fine structure
constant $\alpha$, and the Higgs vacuum expectation value $<v>$ without
assuming any theoretical framework. A variation in $<v>$ leads to a variation
in the electron mass, among other effects. Along the same line, we study the
variation of $\alpha$ and the electron mass $m_e$. In a purely phenomenological
fashion, we derive a relationship between both variations.


title: The automorphism group of the free group of rank two is a CAT(0) group

abstract:
  We prove that the automorphism group of the braid group on four strands acts
faithfully and geometrically on a CAT(0) 2-complex. This implies that the
automorphism group of the free group of rank two acts faithfully and
geometrically on a CAT(0) 2-complex, in contrast to the situation for rank
three and above.


title:
Instability of Standing Waves to the Inhomogeneous Nonlinear
  Schr\"odinger Equation with Harmonic Potential

abstract:
  We study the instability of standing-wave solutions $e^{i\omega
t}\phi_{\omega}(x)$ to the inhomogeneous nonlinear Schr\"{o}dinger equation
$$i\phi_t=-\triangle\phi+|x|^2\phi-|x|^b|\phi|^{p-1}\phi, \qquad
\in\mathbb{R}^N, $$ where $ b > 0 $ and $ \phi_{\omega} $ is a ground-state
solution. The results of the instability of standing-wave solutions reveal a
balance between the frequency $\omega $ of wave and the power of nonlinearity
$p $ for any fixed $ b > 0. $


title: Are fossil groups a challenge of the Cold Dark Matter paradigm?

abstract:
  We study six groups and clusters of galaxies suggested in the literature to
be `fossil' systems (i.e. to have luminous diffuse X-ray emission and a
magnitude gap of at least 2 mag-R between the first and the second ranked
member within half of the virial radius), each having good quality X-ray data
and SDSS spectroscopic or photometric coverage out to the virial radius. The
poor cluster AWM4 is clearly established as a fossil system, and we confirm the
fossil nature of four other systems (RXJ1331.5+1108, RXJ1340.6+4018,
RXJ1256.0+2556 and RXJ1416.4+2315), while the cluster RXJ1552.2+2013 is
disqualified as fossil system. For all systems we present the luminosity
functions within 0.5 and 1 virial radius that are consistent, within the
uncertainties, with the universal luminosity function of clusters. For the five
bona fide fossil systems, having a mass range 2x10^13-3x10^14 M_Sun, we compute
accurate cumulative substructure distribution functions (CSDFs) and compare
them with the CSDFs of observed and simulated groups/clusters available in the
literature. We demonstrate that the CSDFs of fossil systems are consistent with
those of normal observed clusters and do not lack any substructure with respect
to simulated galaxy systems in the cosmological LambdaCDM framework. In
particular, this holds for the archetype fossil group RXJ1340.6+4018 as well,
contrary to earlier claims.


title: The Efficiency of Quantum Identity Testing of Multiple States

abstract:
  We examine two quantum operations, the Permutation Test and the Circle Test,
which test the identity of n quantum states. These operations naturally extend
the well-studied Swap Test on two quantum states. We first show the optimality
of the Permutation Test for any input size n as well as the optimality of the
Circle Test for three input states. In particular, when n=3, we present a
semi-classical protocol, incorporated with the Swap Test, which approximates
the Circle Test efficiently. Furthermore, we show that, with help of classical
preprocessing, a single use of the Circle Test can approximate the Permutation
Test efficiently for an arbitrary input size n.


title: The dense ring in the Coalsack: the merging of two subsonic flows

abstract:
  A recent high angular resolution extinction map toward the most opaque
molecular globule, Globule 2, in the Coalsack Nebula revealed that it contains
a strong central ring of dust column density. This ring represents a region of
high density and pressure that is likely a transient and possibly turbulent
structure. Dynamical models suggest that the ring has formed as a result of a
sudden increase in external pressure which is driving a compression wave into
the Globule. Here we combine the extinction measurements with a detailed study
of the C18O (1-0) molecular line profiles toward Globule 2 in order to
investigate the overall kinematics and, in doing so, test this dynamical model.
We find that the ring corresponds to an enhancement in the C18O non-thermal
velocity dispersion and non-thermal pressure. We observe a velocity gradient
across the Globule that appears to trace two distinct systematic subsonic
velocity flows that happen to converge within the ring. We suggest, therefore,
that the ring has formed as two subsonic flows of turbulent gas merge within
the Globule. The fact that the outer layers of the Globule appear stable
against collapse yet there is no centrally condensed core, suggests that the
Globule may be evolving from the outside in and has yet to stabilize,
confirming its youth.


title:
Magnetic fields and chemical peculiarities of the very young
  intermediate-mass binary system HD 72106

abstract:
  The recently discovered magnetic Herbig Ae and Be stars may provide
qualitatively new information about the formation and evolution of magnetic Ap
and Bp stars. We have performed a detailed investigation of one particularly
interesting binary system with a Herbig Ae secondary and a late B-type primary
possessing a strong, globally ordered magnetic field. Twenty high-resolution
Stokes V spectra of the system were obtained with the ESPaDOnS instrument
mounted on the CFHT. In these observations we see clear evidence for a magnetic
field in the primary, but no evidence for a magnetic field in the secondary. A
detailed abundance analysis was performed for both stars, revealing strong
chemical peculiarities in the primary and normal chemical abundances in the
secondary. The primary is strongly overabundant in Si, Cr, and other iron-peak
elements, as well as Nd, and underabundant in He. The primary therefore appears
to be a very young Bp star. In this context, line profile variations of the
primary suggest non-uniform lateral distributions of surface abundances.
Interpreting the 0.63995 +/- 0.00009 day variation period of the Stokes I and V
profiles as the rotational period of the star, we have modeled the magnetic
field geometry and the surface abundance distributions of Si, Ti, Cr and Fe
using Magnetic Doppler Imaging. We derive a dipolar geometry of the surface
magnetic field, with a polar strength of 1230 G and an obliquity of 57 degrees.
The distributions Ti, Cr and Fe are all qualitatively similar, with an
elongated patch of enhanced abundance situated near the positive magnetic pole.
The Si distribution is somewhat different, and its relationship to the magnetic
field geometry less clear.


title: Alignment of Galaxies and Clusters

abstract:
  We investigated the influence of environment on cluster galaxies by examining
the alignment of the brightest cluster galaxy (BCG) position angle with respect
to the host cluster X-ray position angle. The cluster position angles were
measured using high spatial resolution X-ray data taken from the Chandra ACIS
archive, that significantly improved the determination of the cluster shape
compared to the conventional method of using optical images. Meanwhile, those
of the BCGs were measured using homogeneous dataset composed of high spatial
resolution optical images taken with Suprime-Cam mounted on Subaru 8m
telescope. We found a strong indication of an alignment between the cluster
X-ray emission and optical light from BCGs, while we see no clear direct
correlation between the degree of ellipticity of X-ray and optical BCG
morphologies, despite the apparent alignment of two elliptical structures. We
have also investigated possible dependence of the position angle alignment on
the X-ray morphology of the clusters, and no clear trends are found. The fact
that no trends are evident regarding frequency or degree of the alignment with
respect to X-ray morphology may be consistent with an interpretation as a lack
of dependence on the dynamical status of clusters.