title: Mathematical Foundations of Consciousness

abstract:
  We employ the Zermelo-Fraenkel Axioms that characterize sets as mathematical
primitives. The Anti-foundation Axiom plays a significant role in our
development, since among other of its features, its replacement for the Axiom
of Foundation in the Zermelo-Fraenkel Axioms motivates Platonic
interpretations. These interpretations also depend on such allied notions for
sets as pictures, graphs, decorations, labelings and various mappings that we
use. A syntax and semantics of operators acting on sets is developed. Such
features enable construction of a theory of non-well-founded sets that we use
to frame mathematical foundations of consciousness. To do this we introduce a
supplementary axiomatic system that characterizes experience and consciousness
as primitives. The new axioms proceed through characterization of so- called
consciousness operators. The Russell operator plays a central role and is shown
to be one example of a consciousness operator. Neural networks supply striking
examples of non-well-founded graphs the decorations of which generate
associated sets, each with a Platonic aspect. Employing our foundations, we
show how the supervening of consciousness on its neural correlates in the brain
enables the framing of a theory of consciousness by applying appropriate
consciousness operators to the generated sets in question.


title:
Upper bounds on fault tolerance thresholds of noisy Clifford-based
  quantum computers

abstract:
  We consider the possibility of adding noise to a quantum circuit to make it
efficiently simulatable classically. In previous works this approach has been
used to derive upper bounds to fault tolerance thresholds - usually by
identifying a privileged resource, such as an entangling gate or a non-Clifford
operation, and then deriving the noise levels required to make it
`unprivileged'. In this work we consider extensions of this approach where
noise is added to Clifford gates too, and then `commuted' around until it
concentrates on attacking the non-Clifford resource. While commuting noise
around is not always straightforward, we find that easy instances can be
identified in popular fault tolerance proposals, thereby enabling sharper upper
bounds to be derived in these cases. For instance we find that if we take
Knill's high threshold proposal together with the ability to prepare any
possible state in the $XY$ plane of the Bloch sphere, then no more than 3.69%
error-per-gate noise is sufficient to make it classical, and 13.71% of Knill's
gamma noise model is sufficient. These bounds have been derived without noise
being added to the decoding parts of the circuits. Introducing such noise in a
toy example suggests that the present approach can be optimised further to
yield tighter bounds.


title: Entropy of Hidden Markov Processes via Cycle Expansion

abstract:
  Hidden Markov Processes (HMP) is one of the basic tools of the modern
probabilistic modeling. The characterization of their entropy remains however
an open problem. Here the entropy of HMP is calculated via the cycle expansion
of the zeta-function, a method adopted from the theory of dynamical systems.
For a class of HMP this method produces exact results both for the entropy and
the moment-generating function. The latter allows to estimate, via the Chernoff
bound, the probabilities of large deviations for the HMP. More generally, the
method offers a representation of the moment-generating function and of the
entropy via convergent series.

categories: cs.IT cond-mat.other math.IT physics.data-an


title: Slow imbalance relaxation and thermoelectric transport in graphene

abstract:
  We compute the electronic component of the thermal conductivity (TC) and the
thermoelectric power (TEP) of monolayer graphene, within the hydrodynamic
regime, taking into account the slow rate of carrier population imbalance
relaxation. Interband electron-hole generation and recombination processes are
inefficient due to the non-decaying nature of the relativistic energy spectrum.
As a result, a population imbalance of the conduction and valence bands is
generically induced upon the application of a thermal gradient. We show that
the thermoelectric response of a graphene monolayer depends upon the ratio of
the sample length to an intrinsic length scale l_Q, set by the imbalance
relaxation rate. At the same time, we incorporate the crucial influence of the
metallic contacts required for the thermopower measurement (under open circuit
boundary conditions), since carrier exchange with the contacts also relaxes the
imbalance. These effects are especially pronounced for clean graphene, where
the thermoelectric transport is limited exclusively by intercarrier collisions.
For specimens shorter than l_Q, the population imbalance extends throughout the
sample; the TC and TEP asymptote toward their zero imbalance relaxation limits.
In the opposite limit of a graphene slab longer than l_Q, at non-zero doping
the TC and TEP approach intrinsic values characteristic of the infinite
imbalance relaxation limit. Samples of intermediate (long) length in the doped
(undoped) case are predicted to exhibit an inhomogeneous temperature profile,
whilst the TC and TEP grow linearly with the system size. In all cases except
for the shortest devices, we develop a picture of bulk electron and hole number
currents that flow between thermally conductive leads, where steady-state
recombination and generation processes relax the accumulating imbalance.


title:
The noncommutative Choquet boundary III: Operator systems in matrix
  algebras

abstract:
  We classify operator systems $S\subseteq \mathcal B(H)$ that act on finite
dimensional Hilbert spaces by making use of the noncommutative Choquet
boundary. S is said to be {\em reduced} when its boundary ideal is 0. In the
category of operator systems, that property functions as semisimplicity does in
the category of complex Banach algebras.
  We construct explicit examples of reduced operator systems using sequences of
"parameterizing maps" $\Gamma_k: \mathbb C^r\to \mathcal B(H_k)$, $k=1,..., N$.
We show that every reduced operator system is isomorphic to one of these, and
that two sequences give rise to isomorphic operator systems if and only if they
are "unitarily equivalent" parameterizing sequences.
  Finally, we construct nonreduced operator systems $S$ that have a given
boundary ideal $K$ and a given reduced image in $C^*(S)/K$, and show that these
constructed examples exhaust the possibilities.


title: Vortex Loop Operators, M2-branes and Holography

abstract:
  We construct vortex loop operators in the three-dimensional N = 6
supersymmetric Chern-Simons theory recently constructed by Aharony, Bergman,
Jafferis and Maldacena. These disorder loop operators are specified by a
vortex-like singularity for the scalar and gauge fields along a one dimensional
curve in spacetime. We identify the 1/2, 1/3 and 1/6 BPS loop operators in the
Chern-Simons theory with excitations of M-theory corresponding to M2-branes
ending along a curve on the boundary of AdS_4 x S^7/Z_k. The vortex loop
operators can also be given a purely geometric description in terms of regular
"bubbling" solutions of eleven dimensional supergravity which are
asymptotically AdS_4 x S^7/Z_k.


title: Generalized measurement of uncertainty and the maximizable entropy

abstract:
  For a random variable we can define a variational relationship with practical
physical meaning as dI=dbar(x)-bar(dx), where I is called as uncertainty
measurement. With the help of a generalized definition of expectation,
bar(x)=sum_(i)g(p_i)x_i, and the expression of dI, we can find the concrete
forms of the maximizable entropies for any given probability distribution
function, where g(p_i) may have different forms for different statistics which
includes the extensive and nonextensive statistics.


title:
The Photon Sector in the Quantum Myers-Pospelov Model: An improved
  description

abstract:
  The quantization of the electromagnetic sector of the Myers-Pospelov model
coupled to standard fermions is studied. Our main objective is to construct an
effective quantum theory that results in a genuine perturbation of QED, such
that setting zero the Lorentz invariance violation (LIV) parameters will
reproduce it. This is achieved by introducing an additional low energy scale
$M$, together with a physically motivated prescription to take the QED limit.
The prescription is successfully tested in the calculation of the electron
self-energy in the one loop approximation. The LIV radiative corrections turn
out to be properly scaled by very small factors for any reasonable values of
the parameters, no fine-tuning problems are found at this stage and the choice
for $M$ to be of the order of the electroweak symmetry breaking scale is
consistent with the stringent bounds for the LIV parameters, in particular with
those arising from induced dimension three operators.


title:
Sufficient conditions for thermal rectification in hybrid quantum
  structures

abstract:
  We analytically identify sufficient conditions for manifesting thermal
rectification in two-terminal hybrid structures within the quantum master
equation formalism. We recognize two classes of rectifiers. In type A
rectifiers the contacts are dissimilar. In type B rectifiers the contacts are
equivalent, but the system and baths have different particle statistics, and
the system is (parametrically) asymmetrically coupled to the baths. Our study
applies to various hybrid junctions including metals, dielectrics, and spins.


title:
Pitchfork and Hopf bifurcation threshold in stochastic equations with
  delayed feedback

abstract:
  The bifurcation diagram of a model nonlinear Langevin equation with delayed
feedback is obtained numerically. We observe both direct and oscillatory
bifurcations in different ranges of model parameters. Below threshold, the
stationary distribution function p(x) is a delta function at the trivial state
x=0. Above threshold, p(x) ~ x^alpha at small x, with alpha = -1 at threshold,
and monotonously increasing with the value of the control parameter above
threshold. Unlike the case without delayed feedback, the bifurcation threshold
is shifted by fluctuations by an amount that scales linearly with the noise
intensity. With numerical information about time delayed correlations, we
derive an analytic expression for p(x) which is in good agreement with the
numerical results.


title: Structure-dependent radiative corrections to phi -> K^+K^-/K_LK_S decays

abstract:
  Current predictions for the ratio of phi -> K^+K^-/K_LK_S decay rates exceed
the corresponding experimental value in about five standard deviations. By far,
the dominant sources of isospin breaking to this ratio are the phase-space
(52%) and the electromagnetic radiative (4.3%, computed within scalar QED)
corrections. Here we estimate the effects of the electromagnetic structure of
kaons and other model-dependent contributions into the radiative corrections.


title: Unconstrained Higher Spins of Mixed Symmetry. I. Bose Fields

abstract:
  This is the first of two papers devoted to the local "metric-like"
unconstrained Lagrangians and field equations for higher-spin gauge fields of
mixed symmetry in flat space. Here we complete the previous constrained
formulation of Labastida for Bose fields. We thus recover his Lagrangians via
the Bianchi identities, before extending them to their "minimal" unconstrained
form with higher derivatives of the compensator fields and to yet another,
non-minimal, form with only two-derivative terms. We also identify classes of
these systems that are invariant under Weyl-like symmetries.


title:
Hyperactivated resistance in TiN films on the insulating side of the
  disorder-driven superconductor-insulator transition

abstract:
  We investigate the insulating phase that forms in a titanium nitride film in
a close vicinity of the disorder-driven superconductor-insulator transition. In
zero magnetic field the temperature dependence of the resistance reveals a
sequence of distinct regimes upon decreasing temperature crossing over from
logarithmic to activated behavior with the variable-range hopping squeezing in
between. In perpendicular magnetic fields below 2 T, the thermally activated
regime retains at intermediate temperatures, whereas at ultralow temperatures,
the resistance increases faster than that of the thermally activated type. This
indicates a change of the mechanism of the conductivity. We find that at higher
magnetic fields the thermally activated behavior disappears and the
magnetoresistive isotherms saturate towards the value close to quantum
resistance h/e^2.


title: Discrete Liouville equation and Teichm\"uller theory

abstract:
  The relationship (both classical and quantum mechanical) between the discrete
Liouville equation and Teichm\"uller theory is reviewed.


title: The Age and Metallicity of the Bootes I System

abstract:
  We present Washington photometry of a field central to the Bootes I dwarf
spheroidal galaxy, which was discovered as a stellar overdensity in the Sloan
Digital Sky Survey (DR5). We show that the Washington filters are much more
effective than the Sloan filters in separating the metal-poor turn-off stars in
the dwarf galaxy from the foreground stars. We detect 165 objects in the field,
and statistically determine that just over 40% of the objects are non-members.
Our statistical analysis mostly agrees with radial velocity measurements of the
brighter stars. We find that that there is a distinct main-sequence turn-off
and subgiant branch, where there is some evidence of a spread in chemical
abundance. Any evidence of an age spread is limited to a few billion years. The
brightest 7 Bootes I members give a (photometric-color derived) weighted mean
iron-abundance of [Fe/H]=-2.1+/-0.4, and the best-fit isochrone is the 14.1
Gyr, Z=0.0002 model, with DM=19.11 and E(B-V)=0.02.


title: Sound Mode Hydrodynamics from Bulk Scalar Fields

abstract:
  We study the hydrodynamic sound mode using gauge/gravity correspondence by
examining a generic black brane background's response to perturbations. We
assume that the background is generated by a single scalar field, and then
generalize to the case of multiple scalar fields. The relevant differential
equations obeyed by the gauge invariant variables are presented in both cases.
Finally, we present an analytical solution to these equations in a special
case; this solution allows us to determine the speed of sound and bulk
viscosity for certain special metrics. These results may be useful in
determining sound mode transport coefficients in phenomenologically motivated
holographic models of strongly coupled systems.


title: Sequence alignment and mutual information

abstract:
  Background: Alignment of biological sequences such as DNA, RNA or proteins is
one of the most widely used tools in computational bioscience. All existing
alignment algorithms rely on heuristic scoring schemes based on biological
expertise. Therefore, these algorithms do not provide model independent and
objective measures for how similar two (or more) sequences actually are.
Although information theory provides such a similarity measure -- the mutual
information (MI) -- previous attempts to connect sequence alignment and
information theory have not produced realistic estimates for the MI from a
given alignment.
  Results: Here we describe a simple and flexible approach to get robust
estimates of MI from {\it global} alignments. For mammalian mitochondrial DNA,
our approach gives pairwise MI estimates for commonly used global alignment
algorithms that are strikingly close to estimates obtained by an entirely
unrelated approach -- concatenating and zipping the sequences.
  Conclusions: This remarkable consistency may help establish MI as a reliable
tool for evaluating the quality of global alignments, judging the relative
merits of different alignment algorithms, and estimating the significance of
specific alignments. We expect that our approach can be extended to establish
further connections between information theory and sequence alignment,
including applications to local and multiple alignment procedures.


title:
On the Chebyshev properties of system of eigenfunctions for
  Sturm--Liouville problem with singular coefficients

abstract:
  In the paper we consider singular spectral Sturm--Liouville problem
$-(py')'+(q-\lambda r)y=0$, $(U-1)y^{\vee}+i(U+1)y^{\wedge}=0$, where function
$p\in L_{\infty}[0,1]$ is uniformly positive, generalized function $q\in
W_2^{-1}[0,1]$ is real-valued, generalized weight function $r\in W_2^{-1}[0,1]$
is positive and unitary matrix $U\in\mathbb C^{2\times 2}$ is diagonal. The
goal is to prove that well-known (for smooth case) facts about Chebyshev
property of eigenfunctions hold in general case.


title: Minimal Distortion Morphs Generated by Time-Dependent Vector Fields

abstract:
  A morph between two Riemannian $n$-manifolds is an isotopy between them
together with the set of all intermediate manifolds equipped with Riemannian
metrics. We propose measures of the distortion produced by some classes of
morphs and diffeomorphisms between two isotopic Riemannian $n$-manifolds and,
with respect to these classes, prove the existence of minimal distortion morphs
and diffeomorphisms. In particular, we consider the class of time-dependent
vector fields (on an open subset $\Omega$ of $ \R^{n+1}$ in which the manifolds
are embedded) that generate morphs between two manifolds $M$ and $N$ via an
evolution equation, define the bending and the morphing distortion energies for
these morphs, and prove the existence of minimizers of the corresponding
functionals in the set of time-dependent vector fields that generate morphs
between $M$ and $N$ and are $L^2$ functions from $[0,1]$ to the Sobolev space
$W^{k,2}_0(\Omega,\R^{n+1})$.


title:
Stirring Astronomy into Theology: Sir Isaac Newton on the Date of the
  Passion of Christ

abstract:
  It is known that Sir Isaac Newton suggested a date for the Passion of Christ
in the posthumously published "Observations upon the Prophecies of Daniel and
the Apocalypse of St. John" (1733). What was not known is that the first
attempts to find that date were made during the early period of his life. The
Jewish National and University Library in Jerusalem contains two undated drafts
in Latin under the same title, "Rules for the Determination of Easter", grouped
as Yahuda MS 24E. The earlier draft contains multiple references to the
virtually forgotten "De Annis Christi" (1649), written by Villum Lange, the
17th century Danish astronomer and theologian, who might have been Newton's
first mentor on the Jewish calendar tradition. The second draft shows not only
Newton's close acquaintance with Maimonides' theory of first lunar visibility,
but also his attempt to simplify the latter's criteria by introducing
different, more practical parameters. These "astronomical exercises", announced
in a 1673 book, were likely intended to appear as an appendix to Nicholas
Mercator's 1676 book. Both of Yahuda 24E's drafts contain an astronomical table
with the solar and lunar positions for years 30-37, which Newton used to decide
on the year and date of the Passion. The astronomical data comes from either
1651 "Harmonicon Coeleste" or 1669 "Astronomia Britannica" by Vincent Wing, a
semi-forgotten astronomer of the seventeenth century. This makes Yahuda 24E one
of the earliest of Newton's drafts, likely written in 1669-73 and certainly not
later than 1683/4. A comparison of the two drafts of Yahuda 24E shows that in
the later one, Newton changed his allegiance from St. John's chronology of the
Passion to that shown in the synoptic gospels.


title:
Variability of the methane trapping in martian subsurface clathrate
  hydrates

abstract:
  Recent observations have evidenced traces of methane CH4 heterogeneously
distributed in the martian atmosphere. However, because the lifetime of CH4 in
the atmosphere of Mars is estimated to be around 300-600 years on the basis of
photochemistry, its release from a subsurface reservoir or an active primary
source of methane have been invoked in the recent literature. Among the
existing scenarios, it has been proposed that clathrate hydrates located in the
near subsurface of Mars could be at the origin of the small quantities of the
detected CH4. Here, we accurately determine the composition of these clathrate
hydrates, as a function of temperature and gas phase composition, by using a
hybrid statistical thermodynamic model based on experimental data. Compared to
other recent works, our model allows us to calculate the composition of
clathrate hydrates formed from a more plausible composition of the martian
atmosphere by considering its main compounds, i.e. carbon dioxyde, nitrogen and
argon, together with methane. Besides, because there is no low temperature
restriction in our model, we are able to determine the composition of clathrate
hydrates formed at temperatures corresponding to the extreme ones measured in
the polar caps. Our results show that methane enriched clathrate hydrates could
be stable in the subsurface of Mars only if a primitive CH4-rich atmosphere has
existed or if a subsurface source of CH4 has been (or is still) present.


title:
Velocity autocorrelation function of fluctuating particles in
  incompressible fluids. Toward direct numerical simulation of particle
  dispersions

abstract:
  Motions of fluctuating Brownian particles in an incompressible viscous fluid
have been studied by coupled simulations of Brownian particles and host fluid.
We calculated the velocity autocorrelation functions of Brownian particles and
compared them with the theoretical results. Extensive discussions have been
made on the time scales for which our numerical model is valid.


title: Turbulence in Wind-Blown Bubbles around Massive Stars

abstract:
  Winds from massive stars (> 8 solar masses) result in the formation of
wind-blown "bubbles" around these stars. In this paper we study, via
two-dimensional numerical hydrodynamic simulations, the onset and growth of
turbulence during the formation and evolution of these wind-blown "bubbles".
Our simulations reveal the formation of vortex rolls during the Main-Sequence
stage of the evolution, and Rayleigh-Taylor instabilities in the subsequent
stages due to accelerating and/or decelerating wind-blown shells. The bubble
shows a very turbulent interior just prior to the death of the star, with a
significant percentage of the internal energy expended in non-radial motions.
This would affect the subsequent evolution of the resultant supernova shock
wave. We discuss the implications of these results, show how the ratio of
kinetic energy in radial versus non-radial motions varies throughout the
evolution, and discuss how these results would carry over to three dimensions.


abstract:
  In this work several aspects of ATLAS RPC offline monitoring and data quality
assessment are illustrated with cosmics data selected by RPC trigger. These
correspond to trigger selection, front-end mapping, detection efficiency and
occupancy, which are studied in terms of low level quantities such as: RPC
off-line hits and standalone tracks. The tools and techniques presented are
also extended to the forthcoming LHC p-p beam collisions.


title:
Testing of spin ordering Hamiltonian with ultracold atoms in optical
  lattices

abstract:
  Laser cooling and trapping are now widely used in atomic physics laboratory.
Interestingly, cold atoms in optical lattices are now used in advanced research
to mimic phenomena in condensed matter physics and also as a test laboratory
for the models of these phenomena. It follows then that it is now possible and
necessary to advance the atomic physics laboratory by including the use of
ultracold atoms in optical lattices for instructional contents of phenomena in
condensed matter physics. In this paper, we have proposed how to introduce into
the atomic physics laboratory the study of quantum magnetism with cold atoms in
a double well optical lattice. In particular, we demonstrates how to compare
the theoretical parameters of a spin Hamiltonian model with those extracted
from spin ordering experiment.


title:
Global stability for a class of virus models with CTL immune response
  and antigenic variation

abstract:
  We study the global stability of a class of models for in-vivo virus
dynamics, that take into account the CTL immune response and display antigenic
variation. This class includes a number of models that have been extensively
used to model HIV dynamics. We show that models in this class are globally
asymptotically stable, under mild hypothesis, by using appropriate Lyapunov
functions. We also characterise the stable equilibrium points for the entire
biologically relevant parameter range. As a byproduct, we are able to determine
what is the diversity of the persistent strains.


title:
One-loop QCD and electroweak corrections to $t\bar{t}Z^0$ production at
  an $e^+e^-$ linear collider

abstract:
  We study the impact of the full ${\cal O}(\alpha_{s})$ QCD and ${\cal
O}(\alpha_{ew})$ electroweak (EW) radiative corrections to the $e^+e^- \to t
\bar t Z^0$ process in the standard model (SM), and investigate the dependence
of the lowest-order(LO), one-loop QCD and EW corrected cross sections on
colliding energy $\sqrt{s}$. The LO, QCD and EW corrected spectrums of the
invariant mass of $t\bar t$-pair and the distributions of the transverse
momenta of final top-quark and $Z^0$-boson are presented. The numerical results
show that the one-loop QCD correction enhances the LO cross section, but the EW
one-loop correction generally suppresses the LO cross section with our chosen
parameters. In the case of $m_H=120 GeV$, the QCD relative corrections can
reach 43.16% when $\sqrt{s} = 500 GeV$, while the EW relative corrections have
the values of -9.24%, -4.36% and -5.81%, when $\sqrt{s} = 500 GeV$, $800 GeV$,
1.2 TeV$, respectively.


title: Resource Allocation and Relay Selection for Collaborative Communications

abstract:
  We investigate the relay selection problem for a decode and forward
collaborative network. Users are able to collaborate; decode messages of each
other, re-encode and forward along with their own messages. We study the
performance obtained from collaboration in terms of 1) increasing the
achievable rate, 2) saving the transmit energy and 3) reducing the resource
requirement (resource means time-bandwidth). To ensure fairness, we fix the
transmit-energy-to-rate ratio among all users. We allocate resource optimally
for the collaborative protocol (CP), and compare the result with the
non-collaborative protocol (NCP) where users transmits their messages directly.
The collaboration gain is a function of the channel gain and available energies
and allows us 1) to decide to collaborate or not, 2) to select one relay among
the possible relay users, and 3) to determine the involved gain and loss of
possible collaboration. A considerable gain can be obtained if the direct
source-destination channel gain is significantly smaller than those of
alternative involved links. We demonstrate that a rate and energy improvement
of up to $(1+\sqrt[\eta]{\frac{k}{k+1}})^\eta$ can be obtained, where $\eta$ is
the environment path loss exponent and $k$ is the ratio of the rates of
involved users. The gain is maximum for low
transmit-energy-to-received-noise-ratio (TERN) and in a high TERN environment
the NCP is preferred.


title:
Technology Section of the White Paper on the Status and Future of
  Ground-based TeV Gamma-ray Astronomy

abstract:
  This is a report on the findings of the technology working group for the
white paper on the status and future of TeV gamma-ray astronomy. The white
paper is an APS commissioned document, and the overall version has also been
released and can be found on astro-ph. This detailed section of the white paper
discusses different technology opportunities and the technical feasibility for
substantially improving IACTS and ground based particle detectors to achieve an
order of magnitude better sensitivity than the instruments employed today as
well as their planned upgrades. A technology roadmap for improving IACTS and
ground based particle detectors is presented.


title: Naturalness of CP Violation in the Standard Model

abstract:
  We construct a natural measure on the space of CKM matrices in the standard
model, assuming the fermion mass matrices are randomly selected from a
distribution which fits the observed quark mass hierarchy. This measure allows
us to assess the likelihood of Jarlskog's CP violation parameter J taking its
observed value J $\approx$ 3 x 10^{-5}. While well below the mathematically
allowed maximum, we find that this value is in fact typical, once the observed
quark masses are assumed.


title:
Multi-Instanton Corrections to Superpotentials in Type II
  Compactifications

abstract:
  We consider two simple examples of multi-instanton configurations in type II
4d N=1 superstring compactifications. The first one involves O(1) and U(1)
D2-instantons embedded in T^6/(Z_2 x Z_2') geometry with SU(4) gauge symmetry
coming from D6-branes and the second is related to quiver gauge theory of
orientifolded orbifold of conifold containing fractional D(-1)-instantons and
D3-branes. The additional zero modes of instantons which appear at the
intersection points are lifted through interactions stemming from dimensionally
reduced F- and D-terms. It is shown that multi-instanton configurations
effectively generate corrections to the usual non-perturbative superpotential
for chiral matter.


title:
Crinkles in the last scattering surface: Non-Gaussianity from
  inhomogeneous recombination

abstract:
  The perturbations in the electron number density during recombination
contributes to the Cosmic Microwave Background bispectrum through second order
terms. Perturbations in the electron density can be a factor of ~5 larger than
the baryon density fluctuations on large scales as shown in the calculations by
Novosyadlyj. This raises the possibility that the contribution to bispectrum
arising from perturbations in the optical depth may be non-negligible. We
calculate this bispectrum and find it to peak for squeezed triangles and of
peak amplitude of the order of primordial non-Gaussianity of local type with
fNL of 0.05 ~ -1 depending on the l-modes being considered. This is because the
shape of the bispectrum is different from the primordial one although it peaks
for squeezed configurations, similar to the local type primordial
non-Gaussianity.


title: Welcome back, Polaris the Cepheid

abstract:
  For about 100 years the amplitude of the 4-day pulsation in Polaris has
decreased. We present new results showing a significant increase in the
amplitude based on 4.5 years of continuous monitoring from the ground and with
two satellite missions.


title: Factoring integers with Young's N-slit interferometer

abstract:
  We show that a Young's N slit interferometer can be used to factor the
integer N. The device could factor four- or five-digit numbers in a practical
fashion. This work shows how number theory may arise in physical problems, and
may provide some insight as to how quantum computers can carry out factoring
problems by interferometric means.


title: On 3-lattices and spherical designs

abstract:
  An integral lattice which is generated by some vectors of norm $q$ is called
$q$-lattice. Classification of 3-lattices of dimension at most four is given by
Mimura (On 3-lattice, 2006). As a expansion, we give a classification of
3-lattices of dimension at most seven. In addition, we consider the spherical
designs from its shells.


title: Topological T-duality and T-folds

abstract:
  We explicitly construct the C*-algebras arising in the formalism of
Topological T-duality due to Mathai and Rosenberg from string-theoretic data in
several key examples. We construct a continuous-trace algebra with an action of
${\mathbb R}^d$ unique up to exterior equivalence from the data of a smooth
${\mathbb T}^d$-equivariant gerbe on a trivial bundle $X = W \times {\mathbb
T}^d$. We argue that the `noncommutative T-duals' of Mathai and Rosenberg,
should be identified with the nongeometric backgrounds well-known in string
theory. We also argue that the crossed-product C*-algebra ${\mathcal A}
\rtimes_{\alpha|_{\KZ^d}} {\mathbb Z}^d$ should be identified with the T-folds
of Hull which geometrize these backgrounds.
  We identify the charge group of D-branes on T-fold backgrounds in the
C*-algebraic formalism of Topological T-duality. We also study D-branes on
T-fold backgrounds. We show that the $K$-theory bundles studied by Echterhoff,
Nest and Oyono-Oyono give a natural description of these objects.


title: The three dimensional dynamic structure of the inner Orion Nebula

abstract:
  The three dimensional structure of the brightest part of the Orion Nebula is
assessed in the light of published and new data. We find that the widely
accepted model of a concave blister of ionized material needs to be altered in
the southwest direction from the Trapezium, where we find that the Orion-S
feature is a separate cloud of very optically thick molecules within the body
of ionized gas, which is probably the location of the multiple embedded sources
that produce the outflows that define the Orion-S star formation region.
Evidence for this cloud comes from the presence of H2CO lines in absorption in
the radio continuum and discrepancies in the extinction derived from
radio-optical and optical only emission. We present an equilibrium Cloudy model
of the Orion-S cloud, which successfully reproduces many observed properties of
this feature. We also report the discovery of an open-sided shell of [O III]
surrounding the Trapezium stars, revealed through emission line ratio images
and the onset of radiation shadows beyond some proplyds. We show that the
observed properties of the shell are consistent with it being a stationary
structure, produced by shock interactions between the ambient nebular gas and
the high-velocity wind from theta^1 Ori C. We examine the implications of the
recently published evidence for a large blueshifted velocity of theta^1 Ori C
with respect to the Orion Molecular Cloud, which could mean that this star has
only recently begun to photoionize the Orion Nebula. We show that current
observations of the Nebula do not rule out such a possibility, so long as the
ionization front has propagated into a pre-existing low-density region. In
addition, a young age for the Nebula would help explain the presence of nearby
proplyds with a short mass-loss timescale to photoablation.


title: Birefringence in pseudo-Finsler spacetimes

abstract:
  Based on the analogue spacetime programme, and many other ideas currently
mooted in "quantum gravity", there is considerable ongoing speculation that the
usual pseudo-Riemannian (Lorentzian) manifolds of general relativity might
eventually be modified at short distances. Two specific modifications that are
often advocated are the adoption of Finsler geometries (or more specifically,
pseudo-Finsler spacetimes) and the possibility of birefringence (or more
generally, multi-refringence). We have investigated the possibility of whether
it is possible to usefully and cleanly deal with these two possibilities
simultaneously. That is, given two (or more) "signal cones": Is it possible to
naturally and intuitively construct a "unified" pseudo-Finsler spacetime such
that the pseudo-Finsler metric is null on these "signal cones", but has no
other zeros or singularities? Our results are much less encouraging than we had
originally hoped, and suggest that while pseudo-Finsler spacetimes are
certainly useful constructs, it is physically more appropriate to think of
physics as taking place in a single topological manifold that carries several
distinct pseudo-Finsler metrics, one for each polarization mode.


title:
$\ell$- Volterra Quadratic Stochastic Operators: Lyapunov Functions,
  Trajectories

abstract:
  We consider $\ell$-Volterra quadratic stochastic operators defined on
$(m-1)$-dimensional simplex, where $\ell\in\{0,1,...,m\}$. Under some
conditions on coefficients of such operators we describe Lyapunov functions and
apply them to obtain upper estimates for the set of $\omega$- limit points of
trajectories. We describe a set of fixed points of $\ell$-Volterra operators.


title:
Superdiffusivity for a Brownian polymer in a continuous Gaussian
  environment

abstract:
  This paper provides information about the asymptotic behavior of a
one-dimensional Brownian polymer in random medium represented by a Gaussian
field $W$ on ${\mathbb{R}}_+\times{\mathbb{R}}$ which is white noise in time
and function-valued in space. According to the behavior of the spatial
covariance of $W$, we give a lower bound on the power growth (wandering
exponent) of the polymer when the time parameter goes to infinity: the polymer
is proved to be superdiffusive, with a wandering exponent exceeding any
$\alpha<3/5$.


title:
Two types of softening detected in X-ray afterglows of Swift bursts:
  internal and external shock origins?

abstract:
  The softening process observed in the steep decay phase of early X-ray
afterglows of Swift bursts has remained a puzzle since its discovery. The
softening process can also be observed in the later phase of the bursts and its
cause has also been unknown. Recently, it was suggested that, influenced by the
curvature effect, emission from high latitudes would shift the Band function
spectrum from higher energy band to lower band, and this would give rise to the
observed softening process accompanied by a steep decay of the flux density.
The curvature effect scenario predicts that the terminating time of the
softening process would be correlated with the duration of the process. In this
paper, based on the data from the UNLV GRB group web-site, we found an obvious
correlation between the two quantities. In addition, we found that the
softening process can be divided into two classes: the early type softening
($t_{s,max}\leq "4000"s$) and the late type softening ($t_{s,max} > "4000"s$).
The two types of softening show different behaviors in the duration vs.
terminating time plot. In the relation between the variation rates of the flux
density and spectral index during the softening process, a discrepancy between
the two types of softening is also observed. According to their time scales and
the discrepancy between them, we propose that the two types are of different
origins: the early type is of internal shock origin and the late type is of
external shock origin. The early softening is referred to the steep decay just
following the prompt emission, whereas the late decay typically conceives the
transition from flat decay to late afterglow decay. We suspect that there might
be a great difference of the Lorentz factor in two classes which is responsible
for the observed discrepancy.


title: Photon & Axion Oscillation In a Magnetized Medium: A Covariant Treatment

abstract:
  Pseudoscalar particles, with almost zero mass and very weak coupling to the
visible matter, arise in many extensions of the standard model of particle
physics. Their mixing with photons in the presence of an external magnetic
field leads to many interesting astrophysical and cosmological consequences.
This mixing depends on the medium properties, the momentum of the photon and
the background magnetic field. Here we give a general treatment of
pseudoscalar-photon oscillations in a background magnetic field, taking the
Faraday term into account. We give predictions valid in all regimes, under the
assumption that the frequency of the wave is much higher than the plasma
frequency of the medium. At sufficiently high frequencies, the Faraday effect
is negligible and we reproduce the standard pseudoscalar-photon mixing
phenomenon. However at low frequencies, where Faraday effect is important, the
mixing formulae are considerably modified. We explicitly compute the
contribution due to the longitudinal mode of the photon and show that it is
negligible.


title:
Enhanced production of TeV right-handed neutrinos through the large
  magnetic moment

abstract:
  We examine the effects of magnetic moments of right-handed neutrinos, whose
masses are set at around TeV scale, then it is plausible to have a large
enhancement for the production cross section of TeV scale right-handed
neutrinos though the Drell-Yan process, e^+ e^- to gamma, Z* to N_i N_j, which
is within the reach of the future linear collider (ILC).


title:
Breaking the AMSP mould: the increasingly strange case of HETE
  J1900.1-2455

abstract:
  We present ongoing Rossi X-ray Timing Explorer (RXTE) monitoring observations
of the 377.3 Hz accretion-powered pulsar, HETE J1900.1-2455 Activity continues
in this system more than 3 years after discovery, at a mean luminosity of
4.4e36 erg/s (for d=5 kpc), although pulsations were present only within the
first 70 days. X-ray variability has increased each year, notably with a brief
interval of nondetection in 2007, during which the luminosity dropped to below
1e-3 of the mean level. A deep search of data from the intervals of
nondetection in 2005 revealed evidence for extremely weak pulsations at an
amplitude of 0.29% rms, a factor of ten less than the largest amplitude seen
early in the outburst.
  X-ray burst activity continued through 2008, with bursts typically featuring
strong radius expansion. Spectral analysis of the most intense burst detected
by RXTE early in the outburst revealed unusual variations in the inferred
photospheric radius, as well as significant deviations from a blackbody. We
obtained much better fits instead with a comptonisation model.


title: Morpho-Kinematic Properties of the 21-Micron Source IRAS 07134+1005

abstract:
  We report the results of a Submillimeter Array (SMA) interferometric
observation of 21-micron source IRAS 07134+1005 in the CO J=3-2 line. In order
to determine the morpho-kinematic properties of the molecular envelope of the
object, we constructed a model using the Shape software to model the observed
CO map. We find that the molecular gas component of the envelopes can be
interpreted as a geometrically thick expanding torus with an expanding velocity
of 8 km/s. The inner and outer radii of the torus determined by fitting Shape
models are 1.2" and 3.0", respectively. The inner radius is consistent with the
previous values determined by radiative transfer modeling of the spectral
energy distribution and mid-infrared imaging of the dust component. The radii
and expansion velocity of the torus suggest that the central star has left the
asymptotic giant branch about 1140-1710 years ago, and that the duration of the
equatorial enhanced mass loss is about 2560-3130 years. From the absence of an
observed jet, we suggest that the formation of a bipolar outflow may lack
behind in time from the creation of the equatorial torus.


title: Persistent currents in normal metal rings

abstract:
  The authors have measured the magnetic response of 33 individual cold
mesoscopic gold rings, one ring at a time. The response of some sufficiently
small rings has a component that is periodic in the flux through the ring and
is attributed to a persistent current. Its period is close to h/e, and its sign
and amplitude vary between rings. The amplitude distribution agrees well with
predictions for the typical h/e current in diffusive rings. The temperature
dependence of the amplitude, measured for four rings, is also consistent with
theory. These results disagree with previous measurements of three individual
metal rings that showed a much larger periodic response than expected. The use
of a scanning SQUID microscope enabled in situ measurements of the sensor
background. A paramagnetic linear susceptibility and a poorly understood
anomaly around zero field are attributed to defect spins.


title: On phantom thermodynamics with negative temperature

abstract:
  We discuss the thermodynamic properties of the Friedmann-Robertson-Walker
universe with dark energy fluids labelled by $\omega=p/\rho<-1/3$. Using the
integrability condition, we show that the phantom phase of $w<-1$ can still be
thermodynamically allowed even when the temperature takes on negative values
because in that case, there exists at least a condition of keeping physical
values for $p$ and $\rho$


title: Weak and strong measurement of a qubit using a switching-based detector

abstract:
  We analyze the operation of a switching-based detector that probes a qubit's
observable that does not commute with the qubit's Hamiltonian, leading to a
nontrivial interplay between the measurement and free-qubit dynamics. In order
to obtain analytic results and develop intuitive understanding of the different
possible regimes of operation, we use a theoretical model where the detector is
a quantum two-level system that is constantly monitored by a macroscopic
system. We analyze how to interpret the outcome of the measurement and how the
state of the qubit evolves while it is being measured. We find that the answers
to the above questions depend on the relation between the different parameters
in the problem. In addition to the traditional strong-measurement regime, we
identify a number of regimes associated with weak qubit-detector coupling. An
incoherent detector whose switching time is measurable with high accuracy can
provide high-fidelity information, but the measurement basis is determined only
upon switching of the detector. An incoherent detector whose switching time can
be known only with low accuracy provides a measurement in the qubit's energy
eigenbasis with reduced measurement fidelity. A coherent detector measures the
qubit in its energy eigenbasis and, under certain conditions, can provide
high-fidelity information.


title: Walks with small steps in the quarter plane

abstract:
  Let S be a subset of {-1,0,1}^2 not containing (0,0). We address the
enumeration of plane lattice walks with steps in S, that start from (0,0) and
always remain in the first quadrant. A priori, there are 2^8 problems of this
type, but some are trivial. Some others are equivalent to a model of walks
confined to a half-plane: such models can be solved systematically using the
kernel method, which leads to algebraic generating functions. We focus on the
remaining cases, and show that there are 79 inherently different problems to
study. To each of them, we associate a group G of birational transformations.
We show that this group is finite in exactly 23 cases. We present a unified way
of solving 22 of the 23 models associated with a finite group. For each of
them, the generating function is found to be D-finite. The 23rd model, known as
Gessel's walks, has recently been proved by Bostan et al. to have an algebraic
(and hence D-finite) solution. We conjecture that the remaining 56 models,
associated with an infinite group, have a non-D-finite generating function. Our
approach allows us to recover and refine some known results, and also to obtain
new results. For instance, we prove that walks with N, E, W, S, SW and NE steps
have an algebraic generating function.


title: Polarization and entanglement in spin systems

abstract:
  We established important relationships between entanglement measures and the
order parameter (spin polarization) in nuclear spin systems controlled by the
nuclear magnetic resonance (NMR) technique. Since spin polarization can be
easily manipulated by the NMR technique, experimentalists are presented with an
opportunity to study the dynamic properties of entanglement, i.e., the creation
and evolution of entangled states. Our approach may constitute the basis for
researching the relations between the entanglement measures and measurable
parameters of order in other quantum systems.


title: Homotopy invariants of Gauss phrases

abstract:
  Equivalence relations can be defined on Gauss phrases using combinatorial
moves. In this paper we consider two closely related equivalence relations on
Gauss phrases, homotopy and open homotopy. In particular, in each case, we
define a new invariant and determine the values that it can attain.


title: Local control of spin flow in weak magnetic fields

abstract:
  We demonstrate that optical illumination strongly influences spin transport
in n-type GaAs. Specifically, increasing the power density of optical spin
pumping results in a significant expansion of the spin diffusion profile. A
further means of manipulation is the application of a weak transverse magnetic
field, which strongly increases spin flow out of the excitation spot. These
effects are directly monitored in spin imaging experiments and spatially
resolved Hanle measurements.


title:
Convergence peculiarities of lattice summation upon multiple charge
  spreading generalizing the Bertaut approach

abstract:
  Within investigating the multiple charge spreading generalizing the Bertaut
approach, a set of confined spreading functions with a polynomial behaviour,
but defined so as to enhance the rate of convergence of Coulomb series even
upon a single spreading, is proposed. It is shown that multiple spreading is
ultimately effective especially in the case when the spreading functions of
neighbouring point charges overlap. In the cases of a simple exponential and a
Gaussian spreading functions the effect of multiplicity of spreading on the
rate of convergence is discussed along with an additional optimization of the
spreading parameter in dependence on the cut-off parameters of lattice
summation. All the effects are demonstrated on a simple model NaCl structure.

categories: cond-mat.stat-mech cond-mat.mtrl-sci math-ph math.MP


title: Moduli of Stable Sheaves on a Smooth Quadric in $\PP_3$

abstract:
  We prove that the moduli space of stable sheaves of rank 2 with a certain
Chern classes on a smooth quadric $Q$ in $\PP_3$, is isomorphic to $\PP_3$.
Using this identification, we give a new proof that a certain Brill-Noether
locus on a non-hyperelliptic curve of genus 4, is isomorphic to the
Donagi-Izadi cubic threefold.


title: Gravitational Waves in Relativistic Theory of Gravitation

abstract:
  It is shown that, in the framework of Relativistic Theory of Gravitation with
massive graviton, gravitational waves, due to the causality condition, do not
bear negative energy flows.


title: Electric Dipole Moment and Neutrino Mixing due to Planck Scale Effects

abstract:
  In this paper, we consider the effect of Planck scale operators on electric
dipole moment of the electron de. The electric dipole moment of the electron,
de is known to vanish up to three loops in the standard model with massless
neutrinos We consider the Planck scale operator on neutrino mixing. We assume
that the neutrino masses and mixing arise through physics at a scale
intermediate between Planck scale and the electroweak braking scale. We also
assume, that just above the electroweak breaking scale neutrino mass are nearly
degenerate and the mixing is bi-maximal. Quantum gravity (Planck scale) effects
lead to an effective SU(2)_{L}\times U(1) invariant dimension-5 Lagrangian
symmetry involving Standard Model. On electroweak symmetry breaking, this
operator gives rise to correction to the neutrino masses and mixings these
additional terms can be considered as perturbation to the bimaximal neutrino
mass matrix We assume that the gravitational interaction is flavour blind and
we study the neutrino mixing and electric dipole moment due to the Planck scale
effects.


title: Cusps, self-organization, and absorbing states

abstract:
  Elastic interfaces embedded in (quenched) random media exhibit meta-stability
and stick-slip dynamics. These non-trivial dynamical features have been shown
to be associated with cusp singularities of the coarse-grained disorder
correlator. Here we show that annealed systems with many absorbing states and a
conservation law but no quenched disorder exhibit identical cusps. On the other
hand, similar non-conserved systems in the directed percolation class, are also
shown to exhibit cusps, but of a different type. These results are obtained
both by a recent method to explicitly measure disorder correlators and by
defining an alternative new protocol, inspired by self-organized criticality,
which opens the door to easily accessible experimental realizations.


title: Broad Absorption Line Quasar catalogues with Supervised Neural Networks

abstract:
  We have applied a Learning Vector Quantization (LVQ) algorithm to SDSS DR5
quasar spectra in order to create a large catalogue of broad absorption line
quasars (BALQSOs). We first discuss the problems with BALQSO catalogues
constructed using the conventional balnicity and/or absorption indices (BI and
AI), and then describe the supervised LVQ network we have trained to recognise
BALQSOs. The resulting BALQSO catalogue should be substantially more robust and
complete than BI- or AI-based ones.


title:
Routes to synchrony between asymmetrically interacting oscillator
  ensembles

abstract:
  We report that asymmetrically interacting ensembles of oscillators (AIEOs)
follow novel routes to synchrony. These routes seem to be a characteristic
feature of coupling asymmetry. We show that they are unaffected by white noise
except that the entrainment frequencies are shifted. The probability of
occurrence of the routes is determined by phase asymmetry. The identification
of these phenomena offers new insight into synchrony between oscillator
ensembles and suggest new ways in which it may be controlled.


title: Rapidly Rotating Atomic Gases

abstract:
  This article reviews developments in the theory of rapidly rotating
degenerate atomic gases. The main focus is on the equilibrium properties of a
single component atomic Bose gas, which (at least at rest) forms a
Bose-Einstein condensate. Rotation leads to the formation of quantized vortices
which order into a vortex array, in close analogy with the behaviour of
superfluid helium. Under conditions of rapid rotation, when the vortex density
becomes large, atomic Bose gases offer the possibility to explore the physics
of quantized vortices in novel parameter regimes. First, there is an
interesting regime in which the vortices become sufficiently dense that their
cores -- as set by the healing length -- start to overlap. In this regime, the
theoretical description simplifies, allowing a reduction to single particle
states in the lowest Landau level. Second, one can envisage entering a regime
of very high vortex density, when the number of vortices becomes comparable to
the number of particles in the gas. In this regime, theory predicts the
appearance of a series of strongly correlated phases, which can be viewed as
{\it bosonic} versions of fractional quantum Hall states. This article
describes the equilibrium properties of rapidly rotating atomic Bose gases in
both the mean-field and the strongly correlated regimes, and related
theoretical developments for Bose gases in lattices, for multi-component Bose
gases, and for atomic Fermi gases. The current experimental situation and
outlook for the future are discussed in the light of these theoretical
developments.


title: Green's Function Approach to the Bose-Hubbard Model

abstract:
  We use a diagrammatic hopping expansion to calculate finite-temperature Green
functions of the Bose-Hubbard model which describes bosons in an optical
lattice. This technique allows for a summation of subsets of diagrams, so the
divergence of the Green function leads to non-perturbative results for the
boundary between the superfluid and the Mott phase for finite temperatures.
Whereas the first-order calculation reproduces the seminal mean-field result,
the second order goes beyond and shifts the phase boundary in the immediate
vicinity of the critical parameters determined by the latest high-precision
Monte-Carlo simulations of the Bose-Hubbard model. In addition, our Green's
function approach allows for calculating the excitation spectrum at finite
temperature and for determining the effective masses of particles and holes.


title:
Phase transitions of the mixed spin-1/2 and spin-S Ising model on a
  three-dimensional decorated lattice with a layered structure

abstract:
  Phase transitions of the mixed spin-1/2 and spin-S (S >= 1/2) Ising model on
a three-dimensional (3D) decorated lattice with a layered magnetic structure
are investigated within the framework of a precise mapping relationship to the
simple spin-1/2 Ising model on the tetragonal lattice. This mapping
correspondence yields for the layered Ising model of mixed spins plausible
results either by adopting the conjectured solution for the spin-1/2 Ising
model on the orthorhombic lattice [Z.-D. Zhang, Philos. Mag. 87 (2007)
5309-5419] or by performing extensive Monte Carlo simulations for the
corresponding spin-1/2 Ising model on the tetragonal lattice. It is shown that
the critical behaviour markedly depends on a relative strength of axial
zero-field splitting parameter, inter- and intra-layer interactions. The
striking spontaneous order captured to the 'quasi-1D' spin system is found in a
restricted region of interaction parameters, where the zero-field splitting
parameter forces all integer-valued decorating spins towards their
'non-magnetic' spin state.


title: Efficient Exact Inference in Planar Ising Models

abstract:
  We give polynomial-time algorithms for the exact computation of lowest-energy
(ground) states, worst margin violators, log partition functions, and marginal
edge probabilities in certain binary undirected graphical models. Our approach
provides an interesting alternative to the well-known graph cut paradigm in
that it does not impose any submodularity constraints; instead we require
planarity to establish a correspondence with perfect matchings (dimer
coverings) in an expanded dual graph. We implement a unified framework while
delegating complex but well-understood subproblems (planar embedding,
maximum-weight perfect matching) to established algorithms for which efficient
implementations are freely available. Unlike graph cut methods, we can perform
penalized maximum-likelihood as well as maximum-margin parameter estimation in
the associated conditional random fields (CRFs), and employ marginal posterior
probabilities as well as maximum a posteriori (MAP) states for prediction.
Maximum-margin CRF parameter estimation on image denoising and segmentation
problems shows our approach to be efficient and effective. A C++ implementation
is available from http://nic.schraudolph.org/isinf/


title: The Atiyah algebroid of the path fibration over a Lie group

abstract:
  Let G be a connected Lie group, LG its loop group, and PG->G the principal
LG-bundle defined by quasi-periodic paths in G. This paper is devoted to
differential geometry of the Atiyah algebroid A=T(PG)/LG of this bundle. Given
a symmetric bilinear form on the Lie algebra g and the corresponding central
extension of Lg, we consider the lifting problem for A, and show how the
cohomology class of the Cartan 3-form on G arises as an obstruction. This
involves the construction of a 2-form on PG with differential the pull-back of
the Cartan form. In the second part of this paper we obtain similar
LG-invariant primitives for the higher degree analogues of the Cartan form, and
for their G-equivariant extensions.


title: Topologically trapped vortex molecules in Bose-Einstein condensates

abstract:
  In a numerical experiment based on Gross-Pitaevskii formalism, we demonstrate
unique topological quantum coherence in optically trapped Bose-Einstein
condensates (BECs). Exploring the fact that vortices in rotating BEC can be
pinned by a geometric arrangement of laser beams, we show the parameter range
in which vortex-antivortex molecules or multiquantum vortices are formed as a
consequence of the optically imposed symmetry. Being low-energy states, we
discuss the conditions for spontaneous nucleation of these unique molecules and
their direct experimental observation, and provoke the potential use of the
phase print of an antivortex or a multiquantum vortex when realized in
unconventional circumstances.


title:
Non binary LDPC codes over the binary erasure channel: density evolution
  analysis

abstract:
  In this paper we present a thorough analysis of non binary LDPC codes over
the binary erasure channel. First, the decoding of non binary LDPC codes is
investigated. The proposed algorithm performs on-the-fly decoding, i.e. it
starts decoding as soon as the first symbols are received, which generalizes
the erasure decoding of binary LDPC codes. Next, we evaluate the asymptotical
performance of ensembles of non binary LDPC codes, by using the density
evolution method. Density evolution equations are derived by taking into
consideration both the irregularity of the bipartite graph and the probability
distribution of the graph edge labels. Finally, infinite-length performance of
some ensembles of non binary LDPC codes for different edge label distributions
are shown.


title: Compressing nearly hard sphere fluids increases glass fragility

abstract:
  We use molecular dynamics to investigate the glass transition occurring at
large volume fraction, phi, and low temperature, T, in assemblies of soft
repulsive particles. We find that equilibrium dynamics in the (phi, T) plane
obey a form of dynamic scaling in the proximity of a critical point at T=0 and
phi=phi_0, which should correspond to the ideal glass transition of hard
spheres. This glass point, `point G', is distinct from athermal jamming
thresholds. A remarkable consequence of scaling behaviour is that the dynamics
at fixed phi passes smoothly from that of a strong glass to that of a very
fragile glass as phi increases beyond phi_0. Correlations between fragility and
various physical properties are explored.


title: Evidence for the pair-breaking process in 116,117Sn

abstract:
  The nuclear level densities of 116,117Sn below the neutron separation energy
have been determined experimentally from the (3He,alpha gamma) and (3He,3He
gamma') reactions, respectively. The level densities show a characteristic
exponential increase and a difference in magnitude due to the odd-even effect
of the nuclear systems. In addition, the level densities display pronounced
step-like structures that are interpreted as signatures of subsequent breaking
of nucleon pairs.


title:
Conservation laws and angular transverse shifts of the reflected and
  transmitted light beams

abstract:
  The relation between the angular transverse shifts of the beams reflected and
transmitted at a plane interface of two isotropic transparent media is
established. The derivation of this relation is based on the conservation law
of the transverse component of the Minkowski linear momentum, which takes place
in the processes of the reflection and transmission of wave packets.


title:
Experimental and theoretical challenges for the trapped electron quantum
  computer

abstract:
  We discuss quantum information processing with trapped electrons. After
recalling the operation principle of planar Penning traps we sketch the
experimental conditions to load, cool and detect single electrons. Here we
present a detailed investigation of a scalable scheme including feasibility
studies and the analysis of all important elements, relevant for the
experimental stage. On the theoretical side, we discuss different methods to
couple electron qubits. We estimate the relevant qubit coherence times and draw
implications for the experimental setting. A critical assessment of quantum
information processing with trapped electrons is concluding the article.


title:
Market Mill Dependence Pattern in the Stock Market: Multiscale
  Conditional Dynamics

abstract:
  Market Mill is a complex dependence pattern leading to nonlinear correlations
and predictability in intraday dynamics of stock prices. The present paper puts
together previous efforts to build a dynamical model reflecting the market mill
asymmetries. We show that certain properties of the conditional dynamics at a
single time scale such as a characteristic shape of an asymmetry generating
component of the conditional probability distribution result in the
"elementary" market mill pattern. This asymmetry generating component matches
the empirical distribution obtained from the market data. We discuss these
properties as a mixture of trend-preserving and contrarian strategies used by
market agents. Three basic types of asymmetry patterns characterizing
individual stocks are outlined. Multiple time scale considerations make the
resulting "composite" mill similar to the empirical market mill patterns.
Multiscale model also reflects a multi-agent nature of the market.


title:
Magneto-transmission of multi-layer epitaxial graphene and bulk
  graphite: A comparison

abstract:
  Magneto-transmission of a thin layer of bulk graphite is compared with
spectra taken on multilayer epitaxial graphene prepared by thermal
decomposition of a SiC crystal. We focus on the spectral features evolving as
\sqrt{B}, which are evidence for the presence of Dirac fermions in both
materials. Whereas the results on multi-layer epitaxial graphene can be
interpreted within the model of 2D Dirac fermions, the data obtained on bulk
graphite can only be explained taking into account the 3D nature of graphite,
e.g. by using the standard Slonczewski-Weiss-McClure model.


title: Compression as a tool to detect Bose glass in cold atoms experiments

abstract:
  We suggest that measuring the variation of the radius of an atomic cloud when
the harmonic tap confinement is varied make it possible to monitor the
disappearance of the insulating Mott phase of an ultracold atomic gas trapped
in a disordered optical lattice. This paves the way for an unambiguous
identification of a Bose glass phase in the system.


title: Assessing the relevance of node features for network structure

abstract:
  Networks describe a variety of interacting complex systems in social science,
biology and information technology. Usually the nodes of real networks are
identified not only by their connections but also by some other
characteristics. Examples of characteristics of nodes can be age, gender or
nationality of a person in a social network, the abundance of proteins in the
cell taking part in a protein-interaction networks or the geographical position
of airports that are connected by directed flights. Integrating the information
on the connections of each node with the information about its characteristics
is crucial to discriminating between the essential and negligible
characteristics of nodes for the structure of the network. In this paper we
propose a general indicator, based on entropy measures, to quantify the
dependence of a network's structure on a given set of features.
  We apply this method to social networks of friendships in US schools, to the
protein-interaction network of Saccharomyces cerevisiae and to the US airport
network, showing that the proposed measure provides information which
complements other known measures.


title: Totally geodesic submanifolds in Riemannian symmetric spaces

abstract:
  In the first part of this expository article, the most important
constructions and classification results concerning totally geodesic
submanifolds in Riemannian symmetric spaces are summarized. In the second part,
I describe the results of my classification of the totally geodesic
submanifolds in the Riemannian symmetric spaces of rank 2.


title: Directed current in quasi-adiabatically ac-driven nonlinear systems

abstract:
  We rigorously prove the existence of directed transport for a certain class
of ac-driven nonlinear one dimensional systems, namely the generation of
transport with a preferred direction in the absence of a net driving force.


title:
Symmetric and non-symmetric vortex-antivortex molecules in fourfold
  superconducting geometry

abstract:
  In submicron superconducting squares in a homogeneous magnetic field,
Ginzburg-Landau theory may admit solutions of the vortex-antivortex type,
conforming with the symmetry of the sample [Chibotaru et al., Nature 408, 833
(2000)]. Here we show that these fascinating, but never experimentally observed
states, can be enforced by artificial fourfold pinning, with their diagnostic
features enhanced by orders of magnitude. The second-order nucleation of
vortex-antivortex molecules can be driven either by temperature or applied
magnetic field, with stable asymmetric vortex-antivortex equilibria found on
its path.


title:
On the Impossibility of Electronic Phase Separation in the $D=1,2$
  Dimensional Hubbard Model at T=0

abstract:
  We show explicitly that the one- and two-dimensional Hubbard model does not
show phase separation at any filling at T=0. Apart from a single plausible
assumption, only known exact results and symmetry properties for the one-band
Hubbard model are used. Implications for usage of the simple one-band Hubbard
model for analysing the physics of cuprate superconductors are discussed. We
also discuss models where electronic phase separation might generically occur,
in the specific context of colossal magneto-resistance manganites.


title:
On the Korteweg-de Vries long-wave approximation of the Gross-Pitaevskii
  equation I

abstract:
  The fact that the Korteweg-de-Vries equation offers a good approximation of
long-wave solutions of small amplitude to the one-dimensional Gross-Pitaevskii
equation was derived several years ago in the physical literature. In this
paper, we provide a rigorous proof of this fact, and compute a precise estimate
for the error term. Our proof relies on the integrability of both the
equations. In particular, we give a relation between the invariants of the two
equations, which, we hope, is of independent interest.


title: Bases for spin systems and qudits from angular momentum theory

abstract:
  Spin bases of relevance for quantum systems with cyclic symmetry as well as
for quantum information and quantum computation are constructed from the theory
of angular momentum. This approach is connected to the use of generalized Pauli
matrices (in dimension d) arising from a polar decomposition of the group
SU(2). Numerous examples are given for d=2, 3 and 4.


title: Binding bigraphs as symmetric monoidal closed theories

abstract:
  Milner's bigraphs are a general framework for reasoning about distributed and
concurrent programming languages. Notably, it has been designed to encompass
both the pi-calculus and the Ambient calculus. This paper is only concerned
with bigraphical syntax: given what we here call a bigraphical signature K,
Milner constructs a (pre-) category of bigraphs BBig(K), whose main features
are (1) the presence of relative pushouts (RPOs), which makes them well-behaved
w.r.t. bisimulations, and that (2) the so-called structural equations become
equalities. Examples of the latter include, e.g., in pi and Ambient, renaming
of bound variables, associativity and commutativity of parallel composition, or
scope extrusion for restricted names. Also, bigraphs follow a scoping
discipline ensuring that, roughly, bound variables never escape their scope.
Here, we reconstruct bigraphs using a standard categorical tool: symmetric
monoidal closed (SMC) theories. Our theory enforces the same scoping discipline
as bigraphs, as a direct property of SMC structure. Furthermore, it elucidates
the slightly mysterious status of so-called links in bigraphs. Finally, our
category is also considerably larger than the category of bigraphs, notably
encompassing in the same framework terms and a flexible form of higher-order
contexts.


title: Graphical Presentations of Symmetric Monoidal Closed Theories

abstract:
  We define a notion of symmetric monoidal closed (SMC) theory, consisting of a
SMC signature augmented with equations, and describe the classifying categories
of such theories in terms of proof nets.


title:
Dark Energy and Dark Matter in General Relativity with local scale
  invariance

abstract:
  We consider a generalization of Einstein's general theory of relativity such
that it respects local scale invariance. This requires the introduction of a
scalar and a vector field in the action. We show that the theory naturally
displays both dark energy and dark matter. We solve the resulting equations of
motion assuming an FRW metric. The solutions are found to be almost identical
to those corresponding to the standard $\Lambda$CDM model


title: Wind speed classification using Dirichlet mixtures

abstract:
  Wind energy production is very sensitive to instantaneous wind speed
fluctuations. Thus rapid variation of wind speed due to changes in the local
meteorological conditions can lead to electrical power variations of the order
of the nominal power output. In small grids, as they exist for example on some
islands in the French West Indies, such fluctuations can cause instabilities in
case of intermediate power shortages. To palliate these difficulties, it is
essential to identify and characterize the wind speed distributions. This
allows to anticipate the eventuality of power shortage or power surge.
Therefore, it is of interest to categorize wind speed fluctuations into
distinct classes and to estimate the probability of a distribution to belong to
a class. This paper presents a method for classifying wind speed histograms by
estimating a finite mixture of Dirichlet distributions. The SAEM algorithm that
we use provides a fine distinction between wind speed distribution classes.
It's a new nonparametric method for wind speed sequences classification.
However, we show that the wind speed distributions in each class correspond to
specific Gram- Charlier densities.


title:
Efficient Algorithmic Techniques for Several Multidimensional Geometric
  Data Management and Analysis Problems

abstract:
  In this paper I present several novel, efficient, algorithmic techniques for
solving some multidimensional geometric data management and analysis problems.
The techniques are based on several data structures from computational geometry
(e.g. segment tree and range tree) and on the well-known sweep-line method.


title:
Bond Orientational Order Parameters in the Crystalline Phases of the
  Classical Yukawa-Wigner Bilayers

abstract:
  We present a study of the structural properties of the crystalline phases for
a planar bilayer of particles interacting via repulsive Yukawa potentials in
the weak screening region. The study is done with Monte Carlo computations and
the long ranged contributions to energy are taken into account with the Ewald
method for quasi-two dimensional systems. Two first order phase transitions
(fluid-solid and solid-solid) and one second order transition (solid-solid) are
found when the surface density is varied at constant temperature. A particular
attention is pay to the characteristics of the crystalline phases by the
analysis of bond orientational order parameters and center-to-center
correlations functions.


title:
Evidence for Two-Dimensional Spin-Glass Ordering in Submonolayer Fe
  Films on Cleaved InAs Surfaces

abstract:
  Magnetotransport measurements have been performed on two-dimensional electron
gases formed at InAs(110) surfaces covered with a submonolayer of Fe.
Hysteresis in the magnetoresistance, a difference in remanent magnetoresistance
between zero-field-cooling procedures and field-cooling procedures, and
logarithmic time-dependent relaxation after magnetic field sweep are clearly
observed at 1.7 K for a coverage of 0.42 monolayer. These features are
associated with spin-glass ordering in the Fe film.


title:
Camera distortion self-calibration using the plumb-line constraint and
  minimal Hough entropy

abstract:
  In this paper we present a simple and robust method for self-correction of
camera distortion using single images of scenes which contain straight lines.
Since the most common distortion can be modelled as radial distortion, we
illustrate the method using the Harris radial distortion model, but the method
is applicable to any distortion model. The method is based on transforming the
edgels of the distorted image to a 1-D angular Hough space, and optimizing the
distortion correction parameters which minimize the entropy of the
corresponding normalized histogram. Properly corrected imagery will have fewer
curved lines, and therefore less spread in Hough space. Since the method does
not rely on any image structure beyond the existence of edgels sharing some
common orientations and does not use edge fitting, it is applicable to a wide
variety of image types. For instance, it can be applied equally well to images
of texture with weak but dominant orientations, or images with strong vanishing
points. Finally, the method is performed on both synthetic and real data
revealing that it is particularly robust to noise.


title:
Kshirsagar--Tan independence property of beta matrices and related
  characterizations

abstract:
  A new independence property of univariate beta distributions, related to the
results of Kshirsagar and Tan for beta matrices, is presented. Conversely, a
characterization of univariate beta laws through this independence property is
proved. A related characterization of a family of $2\times2$ random matrices
including beta matrices is also obtained. The main technical challenge was a
problem involving the solution of a related functional equation.


title: Gamma rays from compact binary system

abstract:
  Some of the very high energy (VHE) gamma-ray sources detected with the modern
generation of Cherenkov telescopes have been identified with previously known
X-ray binary systems. These detections demonstrate the richness of non-thermal
phenomena in compact galactic objects containing relativistic outflows or winds
produced near black holes and neutron stars. Recently, the well-known
microquasar Cygnus X-3 seems to be associated with a gamma-ray source detected
with AGILE. Here I summarise the main observational results on gamma-ray
emission from X-ray binaries, as well as some of the proposed scenarios to
explain the production of VHE gamma-rays.


title: Dynamical view of pair creation in uniform electric and magnetic fields

abstract:
  Pair creation in a uniform classical electromagnetic field (Schwinger
mechanism) is studied focusing on the time evolution of the distribution of
created particles. The time evolution of the distribution in time-dependent
fields is also presented as well as effects of back reaction. Motivated by the
Glasma flux tube, which may be formed at the initial stage of heavy-ion
collisions, we investigate effects of a magnetic field parallel to an electric
field, and find that the magnetic field makes the evolution of a fermion system
faster.


title: The staircase structure of the Southern Brazilian Continental Shelf

abstract:
  We show some evidences that the Southeastern Brazilian Continental Shelf
(SBCS) has a devil's staircase structure, with a sequence of scarps and
terraces with widths that obey fractal formation rules. Since the formation of
these features are linked with the sea level variations, we say that the sea
level changes in an organized pulsating way. Although the proposed approach was
applied in a particular region of the Earth, it is suitable to be applied in an
integrated way to other Shelves around the world, since the analyzes favor the
revelation of the global sea level variations.


title: An Eye Tracking Study into the Effects of Graph Layout

abstract:
  Graphs are typically visualized as node-link diagrams. Although there is a
fair amount of research focusing on crossing minimization to improve
readability, little attention has been paid on how to handle crossings when
they are an essential part of the final visualizations. This requires us to
understand how people read graphs and how crossings affect reading performance.
  As an initial step to this end, a preliminary eye tracking experiment was
conducted. The specific purpose of this experiment was to test the effects of
crossing angles and geometric-path tendency on eye movements and performance.
Sixteen subjects performed both path search and node locating tasks with six
drawings. The results showed that small angles can slow down and trigger extra
eye movements, causing delays for path search tasks, whereas crossings have
little impact on node locating tasks. Geometric-path tendency indicates that a
path between two nodes can become harder to follow when many branches of the
path go toward the target node. The insights obtained are discussed with a view
to further confirmation in future work.


title: Central limit theorems for double Poisson integrals

abstract:
  Motivated by second order asymptotic results, we characterize the convergence
in law of double integrals, with respect to Poisson random measures, toward a
standard Gaussian distribution. Our conditions are expressed in terms of
contractions of the kernels. To prove our main results, we use the theory of
stable convergence of generalized stochastic integrals developed by Peccati and
Taqqu. One of the advantages of our approach is that the conditions are
expressed directly in terms of the kernel appearing in the multiple integral
and do not make any explicit use of asymptotic dependence properties such as
mixing. We illustrate our techniques by an application involving linear and
quadratic functionals of generalized Ornstein--Uhlenbeck processes, as well as
examples concerning random hazard rates.


title: Moebius transformations preserving fixed anharmonic ratio

abstract:
  O. Kobayashi in 2007 proved that differentiable mappings preserving
anharmonic ratio are Moebius transformations. We strengthen his result and
prove, that the requirement of differentiability and even of injectivity can be
omitted.


title:
Factorization of number into prime numbers viewed as decay of particle
  into elementary particles conserving energy

abstract:
  Number theory is considered, by proposing quantum mechanical models and
string-like models at zero and finite temperatures, where the factorization of
number into prime numbers is viewed as the decay of particle into elementary
particles conserving energy. In these models, energy of a particle labeled by
an integer $n$ is assumed or derived to being proportional to $\ln n$. The
one-loop vacuum amplitudes, the free energies and the partition functions at
finite temperature of the string-like models are estimated and compared with
the zeta functions. The $SL(2, {\bf Z})$ modular symmetry, being manifest in
the free energies is broken down to the additive symmetry of integers, ${\bf
Z}_{+}$, after interactions are turned on. In the dynamical model existing
behind the zeta function, prepared are the fields labeled by prime numbers. On
the other hand the fields in our models are labeled, not by prime numbers but
by integers. Nevertheless, we can understand whether a number is prime or not
prime by the decay rate, namely by the corresponding particle can decay or can
not decay through interactions conserving energy. Among the models proposed,
the supersymmetric string-like model has the merit of that the zero point
energies are cancelled and the energy levels may be stable against radiative
corrections.


title: The nature of LS 5039 under the scrutiny of gamma-rays

abstract:
  Several gamma-ray binaries have been recently detected by the High-Energy
Stereoscopy Array (H.E.S.S.) and the Major Atmospheric Imaging Cerenkov (MAGIC)
telescope. In two cases, their nature is unknown, since a final observational
feature for a black hole or a pulsar compact object companion is still missing.
One such system is LS 5039. Here we present results from a model (it includes a
detailed account of the system geometry, the angular dependence of processes
such as Klein-Nishina inverse Compton and gamma-gamma absorption, and a Monte
Carlo simulation of cascading) of the high energy phenomenology of LS 5039 in
which it is assumed that the companion object is a pulsar rotating around an
O6.5V star in the 3.9 days orbit. We show that the H.E.S.S. phenomenology at
all scales (spectra along the orbit in both broad and short phase-bins and
lightcurve) is described within this model. We focus on presenting predictions
for photons with lower energies (for E>1 GeV), subject to test in the
forthcoming months with the GLAST satellite, and we also present predictions
for future observations with high-energy arrays, such as H.E.S.S. II. Both set
of predictions go beyond the description of the current data, and could provide
a high-energy determination of the system's composition.


title:
Stabilization of vortex-antivortex configurations in mesoscopic
  superconductors by engineered pinning

abstract:
  Symmetry-induced vortex-antivortex configurations in superconducting squares
and triangles were predicted earlier; yet, they have not been resolved in
experiment up to date. Namely, with vortex-antivortex states being highly
unstable with respect to defects and temperature fluctuations, it is very
unlikely that samples can be fabricated with the needed quality. Here we show
how these drawbacks can be overcome by strategically placed nanoholes in the
sample. As a result, (i) the actual shape of the sample becomes far less
important, (ii) the stability of the vortex-antivortex configurations in
general is substantially enhanced, and (iii) states comprising novel
giant-antivortices (with higher winding numbers) become energetically favorable
in perforated disks. In the analysis, we stress the potent of strong screening
to destabilize the vortex-antivortex states. In turn, the screening-symmetry
competition favors stabilization of new asymmetric ground states, which arise
for small values of the effective Ginzburg-Landau parameter kappa.


title: Stability of symplectic leaves

abstract:
  We find computable criteria for stability of symplectic leaves of Poisson
manifolds. Using Poisson geometry as an inspiration, we also give a general
criterion for stability of leaves of Lie algebroids, including singular ones.
This not only extends but also provides a new approach (and proofs) to the
classical stability results for foliations and group actions.


title: Local times of multifractional Brownian sheets

abstract:
  Denote by $H(t)=(H_1(t),...,H_N(t))$ a function in $t\in{\mathbb{R}}_+^N$
with values in $(0,1)^N$. Let
$\{B^{H(t)}(t)\}=\{B^{H(t)}(t),t\in{\mathbb{R}}^N_+\}$ be an
$(N,d)$-multifractional Brownian sheet (mfBs) with Hurst functional $H(t)$.
Under some regularity conditions on the function $H(t)$, we prove the
existence, joint continuity and the H\"{o}lder regularity of the local times of
$\{B^{H(t)}(t)\}$. We also determine the Hausdorff dimensions of the level sets
of $\{B^{H(t)}(t)\}$. Our results extend the corresponding results for
fractional Brownian sheets and multifractional Brownian motion to
multifractional Brownian sheets.


title:
Spontaneous SUSY breaking with anomalous U(1) symmetry in metastable
  vacua and moduli stabilization

abstract:
  We show that in (anomalous) U(1) gauge theories with the Fayet-Iliopoulos
(FI) term and with generic interactions there are meta-stable vacua in which
supersymmetry (SUSY) is spontaneously broken even without U(1)_R symmetry and
various hierarchical structures, for example, Yukawa hierarchy, can be
explained by the smallness of the FI parameter. When we introduce generic
interactions, i.e., all interactions including higher dimensional interactions
which are allowed by the symmetry of the theory with O(1) coefficients, various
scales can be determined by the symmetry (U(1) charges of the introduced
fields). We examine how to determine the various scales, the vacuum expectation
values (VEVs), and the scales of F-term and of D-term. Moreover, we propose a
new scenario for the stabilization of the moduli in the SUSY breaking models.


title: Randomization Adaptive Self-Stabilization

abstract:
  We present a scheme to convert self-stabilizing algorithms that use
randomization during and following convergence to self-stabilizing algorithms
that use randomization only during convergence. We thus reduce the number of
random bits from an infinite number to a bounded number. The scheme is
applicable to the cases in which there exits a local predicate for each node,
such that global consistency is implied by the union of the local predicates.
We demonstrate our scheme over the token circulation algorithm of Herman and
the recent constant time Byzantine self-stabilizing clock synchronization
algorithm by Ben-Or, Dolev and Hoch. The application of our scheme results in
the first constant time Byzantine self-stabilizing clock synchronization
algorithm that uses a bounded number of random bits.


title: Universal extra dimension: Violation of Kaluza-Klein parity

abstract:
  The minimal Universal Extra Dimension (mUED) model respects the Kaluza-Klein
(KK) parity $(-1)^n$, where $n$ is the KK number. However, it is possible to
have interactions located at only one of the two fixed points of the
$S_1/\ztwo$ orbifold. Such asymmetric interactions violate the KK parity. This
kills the cold dark matter component of UED but also removes the upper bound on
the inverse compactification radius, and thus non-observation of the KK
excitations even at the Large Hadron Collider does not necessarily invalidate
the model. Apart from the decay of the lightest $n=1$ KK excitation, this leads
to collider signals which are markedly different from those in the mUED
scenario. The phenomenological consequences of such KK-parity violating terms
are explored.


title:
Message passing resource allocation for the uplink of multicarrier
  systems

abstract:
  We propose a novel distributed resource allocation scheme for the up-link of
a cellular multi-carrier system based on the message passing (MP) algorithm. In
the proposed approach each transmitter iteratively sends and receives
information messages to/from the base station with the goal of achieving an
optimal resource allocation strategy. The exchanged messages are the solution
of small distributed allocation problems. To reduce the computational load, the
MP problems at the terminals follow a dynamic programming formulation. The
advantage of the proposed scheme is that it distributes the computational
effort among all the transmitters in the cell and it does not require the
presence of a central controller that takes all the decisions. Numerical
results show that the proposed approach is an excellent solution to the
resource allocation problem for cellular multi-carrier systems.


title: Reconnection and merging of positive streamers in air

abstract:
  Pictures show that streamer or sprite discharge channels emerging from the
same electrode sometimes seem to reconnect or merge though their heads carry
electric charge of the same polarity; one might therefore suspect that
reconnections are an artifact of the two-dimensional projection in the
pictures. Here we use stereo-photography to investigate the full
three-dimensional structure of such events. We analyze reconnection, possibly
an electrostatic effect in which a late thin streamer reconnects to an earlier
thick streamer channel, and merging, a suggested photoionization effect in
which two simultaneously propagating streamer heads merge into one new
streamer. We use four different anode geometries (one tip, two tips, two
asymmetric protrusions in a plate, and a wire), placed 40 mm above a flat
cathode plate in ambient air. A positive high voltage pulse is applied to the
anode, creating a positive corona discharge. This discharge is studied with a
fast ICCD camera, in many cases combined with optics to enable stereoscopic
imaging. We find that reconnections as defined above occur frequently. Merging
on the other hand was only observed at a pressure of 25 mbar and a tip
separation of 2 mm, i.e., for a reduced tip distance of p*d=50 micrometer*bar.
In this case the full width at half maximum of the streamer channel is more
than 10 times as large as the tip separation. At higher pressures or with a
wire anode, merging was not observed.


title: The low-mass Initial Mass Function in the young cluster NGC 6611

abstract:
  NGC 6611 is the massive young cluster (2-3 Myr) that ionises the Eagle
Nebula. We present very deep photometric observations of the central region of
NGC 6611 obtained with the Hubble Space Telescope and the following filters:
ACS/WFC F775W and F850LP and NIC2 F110W and F160W, loosely equivalent to
ground-based IZJH filters. This survey reaches down to I ~ 26 mag. We construct
the Initial Mass Function (IMF) from ~ 1.5 Msun well into the brown dwarf
regime (down to ~ 0.02 Msun). We have detected 30-35 brown dwarf candidates in
this sample. The low-mass IMF is combined with a higher-mass IMF constructed
from the groundbased catalogue from Oliveira et al. (2005). We compare the
final IMF with those of well studied star forming regions: we find that the IMF
of NGC 6611 more closely resembles that of the low-mass star forming region in
Taurus than that of the more massive Orion Nebula Cluster (ONC). We conclude
that there seems to be no severe environmental effect in the IMF due to the
proximity of the massive stars in NGC 6611.


title: Optical phenomena in brany Kerr spacetimes

abstract:
  We study the influence of the tidal charge parameter of the braneworld models
onto some optical phenomena in rotating black hole spacetimes. The escape
photon cones are determined for special families of locally non-rotating,
circular geodetical and radially free falling observers. The silhouette of a
rotating black hole, the shape of an equatorial thin accretion disk and time
delay effect for direct and indirect images of a radiation hot spot orbiting
the black hole are given and classified in terms of the black hole rotational
and tidal parameters. It is shown that rising of negatively-valued tidal
parameter, with rotational parameter fixed, generally strenghtens the
relativistic effects and suppresses the rotation induced asymmetries in the
optical phenomena.


title: Some Practical Applications of Dark Matter Research

abstract:
  Two practical spin-offs from the development of cryogenic dark matter
detectors are presented. One in materials research, the other in biology.


title:
Higgs mass bounds from a chirally invariant lattice Higgs-Yukawa model
  with overlap fermions

abstract:
  We study the parameter dependence of the Higgs mass in a chirally invariant
lattice Higgs-Yukawa model emulating the same Higgs-fermion coupling structure
as in the Higgs sector of the electroweak Standard Model. Eventually, the aim
is to establish upper and lower Higgs mass bounds. Here we present our
preliminary results on the lower Higgs mass bound at several selected values
for the cutoff and give a brief outlook towards the upper Higgs mass bound.


title: Exploring Excited Hadrons

abstract:
  Progress in extracting the spectrum of excited hadron resonances is reviewed
and the key issues and challenges in such computations are outlined. The
importance of multi-hadron states as simulations are done with lighter pion
masses is discussed, and the need for all-to-all quark propagators is
emphasized.


title: Quark Lagrangian diagonalization versus non-diagonal kinetic terms

abstract:
  Loop corrections induce a dependence on the momentum squared of the
coefficients of the Standard Model Lagrangian, making highly non-trivial (or
even impossible) the diagonalization of its quadratic part. Fortunately, the
introduction of appropriate counterterms solves this puzzle.


title: Homomorphisms of higher categories

abstract:
  We describe a construction that to each algebraically specified notion of
higher-dimensional category associates a notion of homomorphism which preserves
the categorical structure only up to weakly invertible higher cells. The
construction is such that these homomorphisms admit a strictly associative and
unital composition. We give two applications of this construction. The first is
to tricategories; and here we do not obtain the trihomomorphisms defined by
Gordon, Power and Street, but only something equivalent in a suitable sense.
The second is to Batanin's weak omega-categories.


title: The Mob core language and abstract machine (rev 0.2)

abstract:
  Most current mobile agent systems are based on programming languages whose
semantics are difficult to prove correct as they lack an adequate underlying
formal theory. In recent years, the development of the theory of concurrent
systems, namely of process calculi, has allowed for the first time the modeling
of mobile agent systems.Languages directly based on process calculi are,
however, very low-level and it is desirable to provide the programmer with
higher level abstractions, while keeping the semantics of the base calculus.
  In this technical report we present the syntax and the semantics of a
scripting language for programming mobile agents called Mob. We describe the
language's syntax and semantics. Mob is service-oriented, meaning that agents
act both as servers and as clients of services and that this coupling is done
dynamically at run-time. The language is implemented on top of a process
calculus which allows us to prove that the framework is sound by encoding its
semantics into the underlying calculus. This provides a form of language
security not available to other mobile agent languages developed using a more
ah-doc approach.


title: Comment on: Testing the speed of 'spooky action at a distance'

abstract:
  In a recent experiment, Salart et al. addressed the important issues of the
speed of hypothetical communication and of reference frames in Bell-type
experiments. The authors report that they "performed a Bell experiment using
entangled photons" and conclude from their experimental results that "to
maintain an explanation based on spooky action at a distance we would have to
assume that the spooky action propagates at speeds even greater than the bounds
obtained in our experiment", exceeding the speed of light by orders of
magnitude. Here we show that, analyzing the experimental procedure,
explanations with subluminal or even no communication at all exist for the
experiment.


title: The Physics of Glueballs

abstract:
  Glueballs are particles whose valence degrees of freedom are gluons and
therefore in their description the gauge field plays a dominant role. We review
recent results in the physics of glueballs with the aim set on phenomenology
and discuss the possibility of finding them in conventional hadronic
experiments and in the Quark Gluon Plasma. In order to describe their
properties we resort to a variety of theoretical treatments which include,
lattice QCD, constituent models, AdS/QCD methods, and QCD sum rules. The review
is supposed to be an informed guide to the literature. Therefore, we do not
discuss in detail technical developments but refer the reader to the
appropriate references.