pinecone/core-2020-05-10-deduplication huggingface dataset:
Noncommutative Spheres and Instantons

We report on some recent work on deformation of spaces, notably deformation
of spheres, describing two classes of examples. The first class of examples
consists of noncommutative manifolds associated with the so called
$\theta$-deformations which were introduced out of a simple analysis in terms
of cycles in the $(b,B)$-complex of cyclic homology. These examples have
non-trivial global features and can be endowed with a structure of
noncommutative manifolds, in terms of a spectral triple $(\ca, \ch, D)$. In
particular, noncommutative spheres $S^{N}_{\theta}$ are isospectral
deformations of usual spherical geometries. For the corresponding spectral
triple $(\cinf(S^{N}_\theta), \ch, D)$, both the Hilbert space of spinors $\ch=
L^2(S^{N},\cs)$ and the Dirac operator $D$ are the usual ones on the
commutative $N$-dimensional sphere $S^{N}$ and only the algebra and its action
on $\ch$ are deformed. The second class of examples is made of the so called
quantum spheres $S^{N}_q$ which are homogeneous spaces of quantum orthogonal
and quantum unitary groups. For these spheres, there is a complete description
of $K$-theory, in terms of nontrivial self-adjoint idempotents (projections)
and unitaries, and of the $K$-homology, in term of nontrivial Fredholm modules,
as well as of the corresponding Chern characters in cyclic homology and
cohomology.Comment: Minor changes, list of references expanded and updated. These notes
  are based on invited lectures given at the ``International Workshop on
  Quantum Field Theory and Noncommutative Geometry'', November 26-30 2002,
  Tohoku University, Sendai, Japan. To be published in the workshop proceedings
  by Springer-Verlag as Lecture Notes in Physic
Lectures on Two-Dimensional Noncommutative Gauge Theory 2: Quantization

These notes comprise the second part of two articles devoted to the
construction of exact solutions of noncommutative gauge theory in two spacetime
dimensions. Here we shall deal with the quantum field theory. Topics covered
include an investigation of the symmetries of quantum gauge theory on the
noncommutative torus within the path integral formalism, the derivation of the
exact expression for the vacuum amplitude, and the classification of instanton
contributions. A section dealing with a new, exact combinatorial solution of
gauge theory on a two-dimensional fuzzy torus is also included.Comment: 33 pages, 3 figures, uses svmult.cls; Based on invited lectures given
  by the second author at the ``International Workshop on Quantum Field Theory
  and Noncommutative Geometry'', November 26-30 2002, Tohoku University,
  Sendai, Japan; To be published in the proceedings by Springer-Verlag as
  Lecture Notes in Physic
Baryon Spectroscopy in Lattice QCD

We review recent developments in the study of excited baryon spectroscopy in
lattice QCD. After introducing the basic methods used to extract masses from
correlation functions, we discuss various interpolating fields and lattice
actions commonly used in the literature. We present a survey of results of
recent calculations of excited baryons in quenched QCD, and outline possible
future directions in the study of baryon spectra.Comment: Contribution to Lecture Notes in Physics on Lattice Hadron Physics,
  43 pages, 11 figures, 3 table
Hadron Properties with FLIC Fermions

The Fat-Link Irrelevant Clover (FLIC) fermion action provides a new form of
nonperturbative O(a)-improvement in lattice fermion actions offering near
continuum results at finite lattice spacing. It provides computationally
inexpensive access to the light quark mass regime of QCD where chiral
nonanalytic behaviour associated with Goldstone bosons is revealed. The
motivation and formulation of FLIC fermions, its excellent scaling properties
and its low-lying hadron mass phenomenology are presented.Comment: 29 pages, 13 figures, 6 tables. Contribution to lecure notes in 2nd
  Cairns Topical Workshop on Lattice Hadron Physics 2003 (LHP 2003), Cairns,
  Australia, 22-30 Jul 200
Introduction to Quantum-Gravity Phenomenology

After a brief review of the first phase of development of Quantum-Gravity
Phenomenology, I argue that this research line is now ready to enter a more
advanced phase: while at first it was legitimate to resort to heuristic
order-of-magnitude estimates, which were sufficient to establish that
sensitivity to Planck-scale effects can be achieved, we should now rely on
detailed analyses of some reference test theories. I illustrate this point in
the specific example of studies of Planck-scale modifications of the
energy/momentum dispersion relation, for which I consider two test theories.
Both the photon-stability analyses and the Crab-nebula synchrotron-radiation
analyses, which had raised high hopes of ``beyond-Plankian'' experimental
bounds, turn out to be rather ineffective in constraining the two test
theories. Examples of analyses which can provide constraints of rather wide
applicability are the so-called ``time-of-flight analyses'', in the context of
observations of gamma-ray bursts, and the analyses of the cosmic-ray spectrum
near the GZK scale.Comment: 46 pages, LaTex. Based on lectures given at the 40th Karpacz Winter
  School in Theoretical Physic
Astrophysical Bounds on Planck Suppressed Lorentz Violation

This article reviews many of the observational constraints on Lorentz
symmetry violation (LV). We first describe the GZK cutoff and other phenomena
that are sensitive to LV. After a brief historical sketch of research on LV, we
discuss the effective field theory description of LV and related questions of
principle, technical results, and observational constraints. We focus on
constraints from high energy astrophysics on mass dimension five operators that
contribute to LV electron and photon dispersion relations at order E/M_Planck.
We also briefly discuss constraints on renormalizable operators, and review the
current and future contraints on LV at order (E/M_Planck)^2.Comment: 30 pages, submitted to Lecture Notes in Physics, Quantum Gravity
  Phenomenology, eds. G.Amelino-Camelia, J. Kowalski-Glikman (Springer-Verlag
Inflationary Cosmological Perturbations of Quantum-Mechanical Origin

This review article aims at presenting the theory of inflation. We first
describe the background spacetime behavior during the slow-roll phase and
analyze how inflation ends and the Universe reheats. Then, we present the
theory of cosmological perturbations with special emphasis on their behavior
during inflation. In particular, we discuss the quantum-mechanical nature of
the fluctuations and show how the uncertainty principle fixes the amplitude of
the perturbations. In a next step, we calculate the inflationary power spectra
in the slow-roll approximation and compare these theoretical predictions to the
recent high accuracy measurements of the Cosmic Microwave Background radiation
(CMBR) anisotropy. We show how these data already constrain the underlying
inflationary high energy physics. Finally, we conclude with some speculations
about the trans-Planckian problem, arguing that this issue could allow us to
open a window on physical phenomena which have never been probed so far.Comment: Review Article, 47 pages, 3 figures. Lectures given at the 40th
  Karpacz Winter School on Theoretical Physics (Poland, Feb. 2004), submitted
  to Lecture Notes in Physic
CPT Violation and Decoherence in Quantum Gravity

In these lectures I review, in as much pedagogical way as possible, various
theoretical ideas and motivation for violation of CPT invariance in some models
of Quantum Gravity, and discuss the relevant phenomenology. Since the subject
is vast, I pay particular emphasis on the CPT Violating decoherence scenario
for quantum gravity, due to space-time foam. In my opinion this seems to be the
most likely scenario to be realised in Nature, should quantum gravity be
responsible for the violation of this symmetry. In this context, I also discuss
how the CPT Violating decoherence scenario can explain experimental
``anomalies'' in neutrino data, such as LSND results, in agreement with the
rest of the presently available data, without enlarging the neutrino sector.Comment: 74 pages LATEX, Submitted to Lect. Notes Phys. (Springer), based on
  invited lectures at the 40th Winter School in Poland, February 200
Quantum Foam and Quantum Gravity Phenomenology

Spacetime undergoes quantum fluctuations, giving rise to spacetime foam,
a.k.a. quantum foam. We discuss some properties of spacetime foam, and point
out the conceptual interconnections in the physics of quantum foam, black
holes, and quantum computation. We also discuss the phenomenology of quantum
foam, and conclude that it may be difficult, but by no means impossible, to
detect its tiny effects in the not-too-distant future.Comment: 29 pages, 4 figures, lectures given at the 40th Karpacz Winter School
  on Theoretical Physics (Poland, Feb. 2004), submitted to Lect. Notes Phy
Effects of nanoscale clustering in amorphous carbon

In this review the effects of clustering associated with the sp 2 and sp 3 phases of amorphous carbon thin films are examined. We highlight that many of the optical and electronic properties of these films can be explained by consideration of disorder in the sp 2 phase. Within the context of topological and structural disorder, we explain the variation of the visible Raman line width, Raman shift, Tauc gap and Urbach energy as a function of deposition conditions. We further go on to describe how intra-sp 2 cluster interactions are responsible for the narrowing of the electron paramagnetic resonance line width with increasing spin density and how this intracluster interaction can be extended to the intercluster transport properties, in particular, for electron field emission from the films. We also examine how the mechanical properties of carbon films are affected by clustering which can be enhanced by thermal annealing
Entanglement, Bell Inequalities and Decoherence in Particle Physics

We demonstrate the relevance of entanglement, Bell inequalities and
decoherence in particle physics. In particular, we study in detail the features
of the ``strange'' $K^0 \bar K^0$ system as an example of entangled
meson--antimeson systems. The analogies and differences to entangled spin--1/2
or photon systems are worked, the effects of a unitary time evolution of the
meson system is demonstrated explicitly. After an introduction we present
several types of Bell inequalities and show a remarkable connection to CP
violation. We investigate the stability of entangled quantum systems pursuing
the question how possible decoherence might arise due to the interaction of the
system with its ``environment''. The decoherence is strikingly connected to the
entanglement loss of common entanglement measures. Finally, some outlook of the
field is presented.Comment: Lectures given at Quantum Coherence in Matter: from Quarks to Solids,
  42. Internationale Universit\"atswochen f\"ur Theoretische Physik,
  Schladming, Austria, Feb. 28 -- March 6, 2004, submitted to Lecture Notes in
  Physics, Springer Verlag, 45 page
The art and science of black hole mergers

The merger of two black holes is one of the most extraordinary events in the
natural world. Made of pure gravity, the holes combine to form a single hole,
emitting a strong burst of gravitational radiation. Ground-based detectors are
currently searching for such bursts from holes formed in the evolution of
binary stars, and indeed the very first gravitational wave event detected may
well be a black-hole merger. The space-based LISA detector is being designed to
search for such bursts from merging massive black holes in the centers of
galaxies, events that would emit many thousands of solar masses of pure
gravitational wave energy over a period of only a few minutes. To assist
gravitational wave astronomers in their searches, and to be in a position to
understand the details of what they see, numerical relativists are performing
supercomputer simulations of these events. I review here the state of the art
of these simulations, what we have learned from them so far, and what
challenges remain before we have a full prediction of the waveforms to be
expected from these events.Comment: 12 pages, 3 figures, Proceedings of "Growing Black Holes", Garching
  21-25 June 200
Geometry of isophote curves

In this paper, we consider the intensity surface of a 2D image, we study the
evolution of the symmetry sets (and medial axes) of 1-parameter families of
iso-intensity curves. This extends the investigation done on 1-parameter
families of smooth plane curves (Bruce and Giblin, Giblin and Kimia, etc.) to
the general case when the family of curves includes a singular member, as will
happen if the curves are obtained by taking plane sections of a smooth surface,
at the moment when the plane becomes tangent to the surface.
  Looking at those surface sections as isophote curves, of the pixel values of
an image embedded in the real plane, this allows us to propose to combine
object representation using a skeleton or symmetry set representation and the
appearance modelling by representing image information as a collection of
medial representations for the level-sets of an image.Comment: 15 pages, 7 figure
Efficient Protection of Many-to-One Communications

International audienceThe dependability of a network is its ability to cope with failures , i.e., to maintain established connections even in case of failures. IP routing protocols (such as OSPF and RIP) do not fit the dependability objectives of today applications. Moreover, forwarding techniques based on destination address (like IP) induce many-to-one connections. If a dependable connection is needed, all primary paths and protections having the same destination must be established in a coordinated way. In this paper, we propose a fault recovery for many-to-one connections based on a cold (preplanned) protection. The main advantage of our approach is that the recovery in case of failures is achieved within a short delay. Additionally, with respect to other approaches, the dependability of the routing scheme is increased in the way that it statistically copes with many failures. The algorithm we propose computes an efficient backup for an arbitrary primary tree using an improved multi-tree algorithm
Motif Discovery through Predictive Modeling of Gene Regulation

We present MEDUSA, an integrative method for learning motif models of
transcription factor binding sites by incorporating promoter sequence and gene
expression data. We use a modern large-margin machine learning approach, based
on boosting, to enable feature selection from the high-dimensional search space
of candidate binding sequences while avoiding overfitting. At each iteration of
the algorithm, MEDUSA builds a motif model whose presence in the promoter
region of a gene, coupled with activity of a regulator in an experiment, is
predictive of differential expression. In this way, we learn motifs that are
functional and predictive of regulatory response rather than motifs that are
simply overrepresented in promoter sequences. Moreover, MEDUSA produces a model
of the transcriptional control logic that can predict the expression of any
gene in the organism, given the sequence of the promoter region of the target
gene and the expression state of a set of known or putative transcription
factors and signaling molecules. Each motif model is either a $k$-length
sequence, a dimer, or a PSSM that is built by agglomerative probabilistic
clustering of sequences with similar boosting loss. By applying MEDUSA to a set
of environmental stress response expression data in yeast, we learn motifs
whose ability to predict differential expression of target genes outperforms
motifs from the TRANSFAC dataset and from a previously published candidate set
of PSSMs. We also show that MEDUSA retrieves many experimentally confirmed
binding sites associated with environmental stress response from the
literature.Comment: RECOMB 200
Experience Using a Coordination-Based Architecture for Adaptive Web Content Provision

There are many ways of achieving scalable dynamic web content. In previous work we have focused on dynamic content degradation using a standard architecture and a design-time 'Just In Case' methodology. In this paper, we address certain shortcomings witnessed in our previous work by using an alternate coordination-based architecture, which has interesting applicability to run-time web server adaptation. We first establish the viability of using this architecture for high-volume dynamic web content generation. In doing so, we establish its ability to maintain high throughput in overload conditions. We go on to show how we used the architecture to achieve a 'Just In Time' adaptation to achieve dynamic web content degradation in a running web application server
A lambda calculus for quantum computation with classical control

The objective of this paper is to develop a functional programming language
for quantum computers. We develop a lambda calculus for the classical control
model, following the first author's work on quantum flow-charts. We define a
call-by-value operational semantics, and we give a type system using affine
intuitionistic linear logic. The main results of this paper are the safety
properties of the language and the development of a type inference algorithm.Comment: 15 pages, submitted to TLCA'05. Note: this is basically the work done
  during the first author master, his thesis can be found on his webpage.
  Modifications: almost everything reformulated; recursion removed since the
  way it was stated didn't satisfy lemma 11; type inference algorithm added;
  example of an implementation of quantum teleportation adde
Nonquasiparticle states in half-metallic ferromagnets

Anomalous magnetic and electronic properties of the half-metallic
ferromagnets (HMF) have been discussed. The general conception of the HMF
electronic structure which take into account the most important correlation
effects from electron-magnon interactions, in particular, the spin-polaron
effects, is presented. Special attention is paid to the so called
non-quasiparticle (NQP) or incoherent states which are present in the gap near
the Fermi level and can give considerable contributions to thermodynamic and
transport properties. Prospects of experimental observation of the NQP states
in core-level spectroscopy is discussed. Special features of transport
properties of the HMF which are connected with the absence of one-magnon
spin-flip scattering processes are investigated. The temperature and magnetic
field dependences of resistivity in various regimes are calculated. It is shown
that the NQP states can give a dominate contribution to the temperature
dependence of the impurity-induced resistivity and in the tunnel junction
conductivity. First principle calculations of the NQP-states for the prototype
half-metallic material NiMnSb within the local-density approximation plus
dynamical mean field theory (LDA+DMFT) are presented.Comment: 27 pages, 9 figures, Proceedings of Berlin/Wandlitz workshop 2004;
  Local-Moment Ferromagnets. Unique Properties for Moder Applications, ed. M.
  Donath, W.Nolting, Springer, Berlin, 200
Aspects of the FM Kondo Model: From Unbiased MC Simulations to
  Back-of-an-Envelope Explanations

Effective models are derived from the ferromagnetic Kondo lattice model with
classical corespins, which greatly reduce the numerical effort. Results for
these models are presented. They indicate that double exchange gives the
correct order of magnitude and the correct doping dependence of the Curie
temperature. Furthermore, we find that the jump in the particle density
previously interpreted as phase separation is rather explained by ferromagnetic
polarons.Comment: Proceedings of Wandlitz Days of Magnetism 200
An Origin of CMR: Competing Phases and Disorder-Induced
  Insulator-to-Metal Transition in Manganites

We theoretically explore the mechanism of the colossal magnetoresistance in
manganese oxides by explicitly taking into account the phase competition
between the double-exchange ferromagnetism and the charge-ordered insulator. We
find that quenched disorder causes a drastic change of the multicritical phase
diagram by destroying the charge-ordered state selectively. As a result, there
appears a nontrivial phenomenon of the disorder-induced insulator-to-metal
transition in the multicritical regime. On the contrary, the disorder induces a
highly-insulating state above the transition temperature where charge-ordering
fluctuations are much enhanced. The contrasting effects provide an
understanding of the mechanism of the colossal magnetoresistance. The obtained
scenario is discussed in comparison with other theoretical proposals such as
the polaron theory, the Anderson localization, the multicritical-fluctuation
scenario, and the percolation scenario.Comment: 16 pages, 7 figures, submitted to Wandlitz Days on Magnetism:
  Local-Moment Ferromagnets: Unique Properties for Modern Application
QoS Scalable Tree Aggregation

International audienceIP multicast is not widely deployed over Internet. One of the reasons which prevents its deployment is multicast forwarding state scalability and control explosion. In this paper, we propose an algorithm called Q-STA (QoS Scalable Tree Aggregation) which reduces the number of forwarding states by allowing several groups to share the same tree (the less trees, the less forwarding states). Q-STA performs fast aggregations by evaluating few trees for each aggregation while increasing the number of accepted groups. Q-STA builds trees by using links having a low utilization in order to achieve load balancing. Moreover, groups are aggregated to trees having a minimum number of links in order to minimize the network load. By extensive simulations, we show that Q-STA outperforms the previous algorithm
A priority-aware protection technique for quality of service enabled WDM networks

Connection availability is considered as a critical metric, when providing differentiated services in WDM mesh networks. Indeed, one of the major concerns of optical network operators is related to improving the availability of services provided to their highest-class clients. Achieving this objective is possible through the use of the different classical protection schemes, namely the so-called dedicated and shared protection schemes. However, the majority of the work concerning protection schemes has considered the primary connections as equally important when contending for the use of the backup resources.

As a main contribution in this paper, we therefore propose an improvement of the existing protection schemes through the introduction of relative priorities among the different primary connections contending for the access to the protection path. To evaluate numerically the benefits of the service differentiation feature introduced in our proposal, we first develop a mathematical model based on which we derive explicit expressions for the average connections availabilities that result from both the classical protection schemes and the proposed priority-aware one. Through this model, we show how the availability of the highest-class clients is improved when deploying the proposed priority-aware protection scheme.

Finally, with the same objective in mind, we develop a simulation study, where a given set of connection demands with predefined availability requirements is provisioned, using different protection strategies. Through this study, we show that the priority-aware protection strategy satisfies service-availability requirements in a cost-effective manner compared with the classical protection schemes.N/