pinecone/core-2020-05-10-deduplication huggingface dataset:
Decoherence in Disordered Conductors at Low Temperatures, the effect of
  Soft Local Excitations

The conduction electrons' dephasing rate, $\tau_{\phi}^{-1}$, is expected to
vanish with the temperature. A very intriguing apparent saturation of this
dephasing rate in several systems was recently reported at very low
temperatures. The suggestion that this represents dephasing by zero-point
fluctuations has generated both theoretical and experimental controversies. We
start by proving that the dephasing rate must vanish at the $T\to 0$ limit,
unless a large ground state degeneracy exists. This thermodynamic proof
includes most systems of relevance and it is valid for any determination of
$\tau_{\phi}$ from {\em linear} transport measurements. In fact, our
experiments demonstrate unequivocally that indeed when strictly linear
transport is used, the apparent low-temperature saturation of $\tau_{\phi}$ is
eliminated. However, the conditions to be in the linear transport regime are
more strict than hitherto expected. Another novel result of the experiments is
that introducing heavy nonmagnetic impurities (gold) in our samples produces,
even in linear transport, a shoulder in the dephasing rate at very low
temperatures. We then show theoretically that low-lying local defects may
produce a relatively large dephasing rate at low temperatures. However, as
expected, this rate in fact vanishes when $T \to 0$, in agreement with our
experimental observations.Comment: To appear in the proceedings of the Euresco Conference on Fundamental
  Problems of Mesoscopic Physics, Granada, September 2003, Kluwe
Dephasing and Dynamic Localization in Quantum Dots

The effects of dynamic localization in a solid-state system -- a quantum dot
-- are considered. The theory of weak dynamic localization is developed for
non-interacting electrons in a closed quantum dot under arbitrary
time-dependent perturbation and its equivalence to the theory of weak Anderson
localization is demonstrated. The dephasing due to inelastic electron
scattering is shown to destroy the dynamic localization in a closed quantum dot
leading to the classical energy absorption at times much greater than the
inelastic scattering time. Finally a realistic case of a dot weakly connected
to leads is studied and it is shown that the dynamic localization may lead to a
drastic change of the shape of the Coulomb blockade peak in the dc conductance
vs the gate voltage.Comment: 24 pages, 7 figures, Proceeding of the NATO Conference "Fundamental
  Problems of Mesoscopic Physics: Interaction and Decoherence.", Granada
  (Spain
Mesoscopic Aharonov-Bohm oscillations in metallic rings

We study the amplitude of mesoscopic Aharonov-Bohm oscillations in
quasi-one-dimensional (Q1D) diffusive rings. We consider first the
low-temperature limit of a fully coherent sample. The variance of oscillation
harmonics is calculated as a function of the length of the leads attaching the
ring to reservoirs. We further analyze the regime of relatively high
temperatures, when the dephasing due to electron-electron interaction
suppresses substantially the oscillations. We show that the dephasing length
L_phi^AB governing the damping factor exp(-2pi R /L_phi^AB) of the oscillations
is parametrically different from the common dephasing length for the Q1D
geometry. This is due to the fact that the dephasing is governed by energy
transfers determined by the ring circumference 2pi R, making L_phi^AB
R-dependent.Comment: 16 pages, 4 figures, to appear in proceedings of NATO/Euresco
  Conference "Fundamental Problems of Mesoscopic Physics: Interactions and
  Decoherence", Granada (Spain), September 200
Local and non-local approaches to fatigue crack initiation and propogation

Copyright @ 2003 Kulwer Academic Publishers.A functional form of local strength conditions under fatigue loading is introduced and employed to formulation and analysis of fatigue crack initiation and propagation. For the strength conditions associated with the Palmgren-Miner linear damage accumulation rule and the power-type S-N diagram, the problem is reduced to a non-linear integral Volterra equation, which can be transformed to a linear one for the case of a single crack. An analytical solution of some simple problems are presented for the latter case and shortcomings of the local approach are pointed out. A non-local approach free from the shortcomings is presented along with an example of its implementation.This work was completed under the research grant GR/M24592 "Non-local approach to\ud
high cyclic fatigue: Theoretical basis" of the Engineering and Physical Sciences Research Council, UK
Asymptotic homogenisation in strength and fatigue durability analysis of composites

This is the post-print version of the Article. Copyright @ 2003 Kluwer Academic Publishers.Asymptotic homogenisation technique and two-scale convergence is used for analysis of macro-strength and fatigue durability of composites with a periodic structure under cyclic loading. The linear damage accumulation rule is employed in the phenomenological micro-durability conditions (for each component of the composite) under varying cyclic loading. Both local and non-local strength and durability conditions are analysed. The strong convergence of the strength as the structure period tends to zero is proved and its limiting value is estimated.This work was supported under the research grant GR/M24592 from the Engineering and Physical Sciences Research Council, UK
Tensor and spin representations of SO(4) and discrete quantum gravity

Starting from the defining transformations of complex matrices for the SO(4)
group, we construct the fundamental representation and the tensor and spinor
representations of the group SO(4). Given the commutation relations for the
corresponding algebra, the unitary representations of the group in terms of the
generalized Euler angles are constructed. These mathematical results help us to
a more complete description of the Barrett-Crane model in Quantum Gravity. In
particular a complete realization of the weight function for the partition
function is given and a new geometrical itnerpretation of the asymptotic limit
for the Regge action is presented.Comment: LaTeX, 18 pages, 1 eps figure. Communication presented to the
  International Symposium Symmetries in Science XIII, July 2003, Bregenz. To be
  published by Kluwe
Fractal time random walk and subrecoil laser cooling considered as
  renewal processes with infinite mean waiting times

There exist important stochastic physical processes involving infinite mean
waiting times. The mean divergence has dramatic consequences on the process
dynamics. Fractal time random walks, a diffusion process, and subrecoil laser
cooling, a concentration process, are two such processes that look
qualitatively dissimilar. Yet, a unifying treatment of these two processes,
which is the topic of this pedagogic paper, can be developed by combining
renewal theory with the generalized central limit theorem. This approach
enables to derive without technical difficulties the key physical properties
and it emphasizes the role of the behaviour of sums with infinite means.Comment: 9 pages, 7 figures, to appear in the Proceedings of Cargese Summer
  School on "Chaotic dynamics and transport in classical and quantum systems
Recognition of learning through work

The recognition of skills is important to individuals. The acquisition of qualifications, their level and standing is correlated to levels of remuneration (Groot, Hartog, & Oosterbeek, 1994; Grubb, 1996; Lengerman, 1999; O'Connell, 1999), associated with occupational identity (e.g. Noon and Blyton, 1997, Pusey 2003) and, likely, the standing of the work individuals are permitted to engage in (e.g. Darrah, 1996). Those whose work is low paid and least valued (e.g. women, migrants, non-native speakers) often have the greatest need for skill recognition. Yet, for many workers there exists no bases or mechanism for their skills to be recognised, because of a lack of courses or other means of recognition. Given that workplaces are key sites for learning and demonstrating the knowledge required for work, they present an option for the recognition and certification of work skills that can assist overcome disadvantage and also be used to maintain the recognition of skills throughout working life. Yet, currently, the practice of the recognition and certification of skills learnt through work is underdeveloped and constrained by complexities in its organisation and enactment that have particular and significant policy implications. It follows that understanding further how the recognition of workplace learnt knowledge might be best enacted and identifying policies and practices to support its enactment are worthy and timely goals.Arts, Education & Law Group, School of Education and Professional StudiesFull Tex
Minimum Distance Requirements and Liability: Implications for Co-Existence

The co-existence of conventional and transgenic products in the food chain introduces new elements in the evaluation of the profitability of transgenic crops and, consequently, on the farmer’s adoption decision. In particular, one emerging problem farmers are facing in Europe is related to the legal liability of transgenic crop cultivation. In Europe, a mixture of ex-ante regulations and ex-post liability rules governing transgenic crops emerges. 
One of the predominant ex-ante regulations discussed at the EU-level is a minimum distance requirement to neighbouring fields in order to avoid cross-pollination. The ex-post liability rules differ. They depend on the legal frameworks of individual members of the EU. The current interpretation of, for example, Italian and German law does not exclude ex-post liability for farmers planting transgenic crops in the case of cross-pollination.
In this paper, we analyze the value of planting transgenic crops when farmers face ex-ante regulatory and ex-post liability costs under irreversibility and uncertainty. The regulatory instrument analyzed is the minimum distance to neighbouring fields. First results indicate that under irreversibility and uncertainty the value of cultivating transgenic crops presents a trade-off between ex-ante regulatory and ex-post liability costs with respect to farm size. From this, it is not possible to conclude a priori the net effect on the size of the adopting farms, if, ceteris paribus, a minimum distance regulation is adopted within the EU and farmers can be held liable ex-post.
Distant Entanglement of Macroscopic Gas Samples

One of the main ingredients in most quantum information protocols is a
reliable source of two entangled systems. Such systems have been generated
experimentally several years ago for light but has only in the past few years
been demonstrated for atomic systems. None of these approaches however involve
two atomic systems situated in separate environments. This is necessary for the
creation of entanglement over arbitrary distances which is required for many
quantum information protocols such as atomic teleportation. We present an
experimental realization of such distant entanglement based on an adaptation of
the entanglement of macroscopic gas samples containing about 10^11 cesium atoms
shown previously by our group. The entanglement is generated via the
off-resonant Kerr interaction between the atomic samples and a pulse of light.
The achieved entanglement distance is 0.35m but can be scaled arbitrarily. The
feasibility of an implementation of various quantum information protocols using
macroscopic samples of atoms has therefore been greatly increased. We also
present a theoretical modeling in terms of canonical position and momentum
operators X and P describing the entanglement generation and verification in
presence of decoherence mechanisms.Comment: 20 pages book-style, 3 figure
Broken Symmetry and Coherence of Molecular Vibrations in Tunnel
  Transitions

We examine the Breit-Wigner resonances that ensue from field effects in
molecular single electron transistors (SETs). The adiabatic dynamics of a
quantum dot elastically attached to electrodes are treated in the
Born-Oppenheimer approach. The relation between thermal and shot noise induced
by the source-drain voltage $V_{bias}$ is found when the SET operates in a
regime tending to thermodynamic equilibrium far from resonance. The
equilibration of electron-phonon subsystems produces broadening and doublet
splitting of transparency resonances helping to explain a negative differential
resistance (NDR)of current versus voltage (I-V) curves. Mismatch between the
electron and phonon temperatures brings out the bouncing-ball mode in the
crossover regime close to the internal vibrations mode. The shuttle mechanism
occurs at a threshold $V_{bias}$ of the order of the Coulomb energy $U_c$. An
accumulation of charge is followed by the Coulomb blockade and broken symmetry
of a single or double well potential. The Landau bifurcation cures the
shuttling instability and the resonance levels of the quantum dot become split
because of molecular tunneling. We calculate the tunnel gaps of conductivity
and propose a tunneling optical trap (TOT) for quantum dot isolation permitting
coherent molecular tunneling by virtue of Josephson oscillations in a charged
Bose gas. We discuss experimental conditions when the above theory can be
tested.Comment: 45 pages, 18 figures; The talk presented at Workshop "Decoherence,
  Entanglement and Information Protection in Complex Quantum Systems", Les
  Houches, April 25 -30, 2004. Corrected typos and minor grammatical and
  stylistic changes; Editors: V. M. Akulin, A. Sarfati, G. Kurizki and S.
  Pellegrin Publisher: Kluwer Academic Publisher, Boston / Dordrecht / London:
  to appear in 2005 (February / March
Statistical Physics of Rupture in Heterogeneous Media

The damage and fracture of materials are technologically of enormous interest
due to their economic and human cost. They cover a wide range of phenomena like
e.g. cracking of glass, aging of concrete, the failure of fiber networks in the
formation of paper and the breaking of a metal bar subject to an external load.
Failure of composite systems is of utmost importance in naval, aeronautics and
space industry. By the term composite, we refer to materials with heterogeneous
microscopic structures and also to assemblages of macroscopic elements forming
a super-structure. Chemical and nuclear plants suffer from cracking due to
corrosion either of chemical or radioactive origin, aided by thermal and/or
mechanical stress. Despite the large amount of experimental data and the
considerable effort that has been undertaken by material scientists, many
questions about fracture have not been answered yet. There is no comprehensive
understanding of rupture phenomena but only a partial classification in
restricted and relatively simple situations. This lack of fundamental
understanding is indeed reflected in the absence of reliable prediction methods
for rupture, based on a suitable monitoring of the stressed system. Not only is
there a lack of non-empirical understanding of the reliability of a system, but
also the empirical laws themselves have often limited value. The difficulties
stem from the complex interplay between heterogeneities and modes of damage and
the possible existence of a hierarchy of characteristic scales (static and
dynamic).
  The paper presents a review of recent efforts from the statistical physics
community to address these points.Comment: Enlarged review and updated references, 21 pages with 2 figure
Electronic structure methods: Augmented Waves, Pseudopotentials and the
  Projector Augmented Wave Method

The main goal of electronic structure methods is to solve the Schroedinger
equation for the electrons in a molecule or solid, to evaluate the resulting
total energies, forces, response functions and other quantities of interest. In
this paper we describe the basic ideas behind the main electronic structure
methods such as the pseudopotential and the augmented wave methods and provide
selected pointers to contributions that are relevant for a beginner. We give
particular emphasis to the Projector Augmented Wave (PAW) method developed by
one of us, an electronic structure method for ab-initio molecular dynamics with
full wavefunctions. We feel that it allows best to show the common conceptional
basis of the most widespread electronic structure methods in materials science.Comment: to appear in: Handbook of Materials Modeling; Volume 1: Methods and
  Models, Sidney Yip (Ed.); Kluwer Academic Publisher
Efficient Calculation of Electron States in Self-Assembled Quantum Dots: Application to Auger Relaxation

This is the author's final draft of the paper published as: Quantum Dots: Fundamentals, Applications, and Frontiers: Proceedings of the NATO Advanced Research Workshop on Quantum Dots: Fundamentals, Applications and Frontiers Crete, Greece, 20-24 July 2003 / edited by Bruce A. Joyce, Pantelis C. Kelires, Anton G. Naumovets, Dimitri D. Vvedensky, pp. 239-255.  The final version is available from http://www.springerlink.com/content/k56545x7806611m4/.  Doi: 10.1007/1-4020-3315-X_16An efficient method for calculation of self-assembled dot states within the effective mass approximation is described and its application to the calculation of Auger relaxation rates is detailed. The method is based on expansion of the dot states in a harmonic oscillator basis whose parameters are optimised to improve the convergence rate. This results in at least an order of magnitude reduction in the number of basis states required to represent electron states accurately compared to the conventional plane wave approach. Auger relaxation rates are calculated for harmonic oscillator model states and exact states for various pyramidal models. The dipole approximation, previously used to calculate Auger rates, is found to be inaccurate by a factor of around 2–3. The harmonic oscillator states do not reproduce the rates for the more realistic pyramidal models very well and even within the set of pyramidal models variations in the dot shape and size can change the rates by up to an order of magnitude. Typical Auger relaxation rates are on a picosecond timescale but the actual value is strongly dependent on the density of electrons outside the dot
Efficient Path Openings And Closings

Path openings and closings are algebraic morphological operators using families of thin and oriented structuring elements that are not necessarily perfectly straight. These operators are naturally translation invariant and can be used in filtering applications instead of operators based on the more standard families of straight line structuring elements. They give similar results to area or attribute based operators but with more flexibility in the constraints. Trivial implementations of this idea using actual suprema or infima of morphological operators with paths as structuring elements would imply exponential complexity. Fortunately a linear complexity algorithm exists in the literature, which has similar running times as an efficient implementation of algebraic operators using straight lines as structuring elements. However even this implementation is sometimes not fast enough, leading practitioners to favour some attribute-based operators instead, which in some applications is not optimal. In this paper we propose an implementation of path-based morphological operators which has logarithmic complexity and comparable computing times with those of attribute-based operators
Image Filtering Using Morphological Amoebas

International audienceThis article presents the use of anisotropic dynamic structuring elements, or amoebas, in order to build content-aware noise reduction filters. The amoeba is the ball defined by a special geodesic distance computed for each pixel, and can be used as a kernel for many kinds of filters and morphological operators. 1. Introduction Noise is possibly the most annoying problem in the field of image processing. There are two ways to work around it: either design particularly robust algorithms that can work in noisy environments, or try to eliminate the noise in a first step while losing as little relevant information as possible and consequently use a normally robust algorithm. There are of course many algorithms that aim at reducing the amount of noise in images. In mathematical morphology filters can be, broadly-speaking, divided into two groups: 1 alternate sequential filters based on morphological openings and clos-ings, that are quite effective but also remove thin elements such as canals or peninsulas. Even worse, they can displace the contours and thus create additional problems in a segmentation application
Cost models for sand casting : the limits of a generic approach

International audienceIn the early phases of the product life cycle, cost controls became a major decision tool in the competitiveness of companies due to world competition. After defining the problems related to these control difficulties, we will present an approach using a concept of cost entity related to the design and realization activities of the product. We will try to apply this approach to the fields of the sand casting foundry. This work will highlight the enterprise modelling difficulties (limits of a global cost modelling approach) and some specifics limitations of the tool used for this development. Finally we will discuss the limits of a generic approach
Star Formation Efficiencies and Star Cluster Formation

Starbursts produce large numbers of Young Star Clusters (YSCs). Multi-color photometry in combination with a dedicated SED analysis tool allows to derive ages, metallicities, EB???V, and masses including 1 uncertainties for individual clusters and, hence, mass functions for YSC systems. The mass function, known to be Gaussian for old Globular Cluster (GC) systems, is still controversial for YSC systems. GC formation is expected in massive gas-rich spiral ??? spiral mergers because of their high global star formation efficiencies and observed in 1 Gyr old merger remnants. Yet it has not been possible to identify young GCs among YSC populations. We suggest a compactness parameters involving masses and half-light radii of YSCs to investigate if young GCs are formed in starbursts and if the ratio of young GCs to more loosely bound star clusters depends on galaxy type, mass, burst strength, etc
Strings and D-branes in holographic backgrounds

We review recent progress in the study of non-rational (boundary) conformal
field theories and their applications to describe exact holographic backgrounds
in superstring theory. We focus mainly on the example of the supersymmetric
coset SL(2,R)/U(1), corresponding to the two-dimensional black hole, and its
dual N=2 Liouville. In particular we discuss the modular properties of their
characters, their partition function as well as the exact boundary states for
their various D-branes. Then these results are used to construct the
corresponding quantities in the CFT of the NS5-brane background, with
applications to Little String Theories.Comment: 5 pages, one figure; contribution to the proceedings of RTN Workshop,
  Kolymbari, Crete, Greece, 5-10 September 200
Theory of Cosmological Perturbations and Applications to Superstring
  Cosmology

The theory of cosmological perturbations is the main tool which connects
theories of the early universe (based on new fundamental physics such as string
theory) with cosmological observations. In these lectures, I will provide an
introduction to this theory, beginning with an overview of the Newtonian theory
of fluctuations, moving on to the analysis of fluctuations in the realm of
classical general relativity, and culminating with a discussion of the quantum
theory of cosmological perturbations. I will illustrate the formalism with
applications to inflationary cosmology. I will review the basics of
inflationary cosmology and discuss why - through the evolution of fluctuations
- inflation may provide a way of observationally testing Planck-scale physics.Comment: Writeup of lectures delivered at the 2004 Cargese Summer School on
  String Theory, 49 pages, 3 figure