Search results for " Exclusion"
showing 10 items of 248 documents
Dephasing of orbital and spin degrees of freedom in semiconductor quantum dots due to phonons and magnons
2006
Phonon-induced decoherence of orbital degrees of freedom in quantum dots (QDs) (GaAs/InAs) is studied and the relevant time-scales are estimated versus dot dimension. Dephasing of excitons due to acoustic phonons and optical phonons, including enhancement of the effective Frohlich constant caused by localization, is assessed for the state-of-art QDs. Temporal inefficiency of Pauli blocking in QDs due to lattice inertia is additionally predicted. For QD placed in a diluted magnetic semiconductor medium a magnon induced dephasing of spin is estimated in accordance with experimental results for Zn(Mn)Se/CdSe. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Unavoidable decoherence in semiconductor quantum dots
2005
Phonon-induced unavoidable decoherence of orbital degrees of freedom in quantum dots is studied and the relevant time scales are estimated. Dephasing of excitons due to acoustic phonons and, in a polar medium, to optical phonons, including anharmonic effects and enhancement of the effective Fr\"ohlich constant due to localization, is assessed for typical self-assembled quantum dots. Temporal inefficiency of Pauli blocking due to lattice inertia is predicted. For quantum dots placed in a diluted magnetic semiconductor medium a magnon-induced dephasing of a spin is also estimated in accordance with experimental results.
Testing electromagnetic proton form factors in the annihilation process p+p¯→π0+e−+e+
2011
We study the annihilation channel in proton antiproton collisions with production of a single neutral pion and an electron-positron pair. It is shown that this reaction allows access to the proton electromagnetic form factors in the ‘unphysical’ region and to the difference between complex phases of the Dirac and Pauli proton form factors. The differential cross section is given in the laboratory frame in an experimental setup where all outgoing particles are fully detected.
Composite Operator Method analysis of the underdoped cuprates puzzle
2014
The microscopical analysis of the unconventional and puzzling physics of the underdoped cuprates, as carried out lately by means of the Composite Operator Method (COM) applied to the 2D Hubbard model, is reviewed and systematized. The 2D Hubbard model has been adopted as it has been considered the minimal model capable to describe the most peculiar features of cuprates held responsible for their anomalous behavior. COM is designed to endorse, since its foundations, the systematic emergence in any SCS of new elementary excitations described by composite operators obeying non-canonical algebras. In this case (underdoped cuprates - 2D Hubbard model), the residual interactions - beyond a 2-pole…
Shell structure in mixed3He−4Hedroplets
2004
Due to the immiscibility of ${}^{3}\mathrm{He}$ into ${}^{4}\mathrm{He}$ at very low temperatures, mixed helium droplets consist of a core of ${}^{4}\mathrm{He}$ atoms coated by a ${}^{3}\mathrm{He}$ layer whose thickness depends on the number of atoms of each isotope. When these numbers are such that the centrifugal kinetic energy of the ${}^{3}\mathrm{He}$ atoms is small and can be considered as a perturbation to the mean-field energy, a novel shell structure arises, with magic numbers different from these of pure ${}^{3}\mathrm{He}$ droplets. If the outermost shell is not completely filled, the valence atoms align their spins up to the maximum value allowed by the Pauli principle.
The Pauli Principle and Systems Consisting of Composite Particles
1993
In nature we often deal with many-body systems that are described in terms of particles that are not elementary but themselves composite. Examples of such composite particles are hadrons, atoms, phonons, and Cooper pairs. For the description of systems consisting of such composite particles in terms of the underlying degrees of freedom group theory plays an important role, in particular the symmetric group to describe the permutational symmetry of the wave function of the system, and unitary groups to describe the symmetry forced on the system by the interaction between the particles.
La Territorialización de las Políticas de Inclusión Social desde el punto de Vista de los Espacios Rurales Españoles: Comparativa Autonómica
2020
En el artículo examinamos cómo se materializa la atención al medio rural en los planes de inclusión social españoles. Analizamos el marco estatal y autonómico clasificando las Comunidades Autónomas según su grado de ruralidad (OCDE). Así, establecemos si existe relación entre el carácter territorial de cada CCAA y el tipo de acciones inclusivas planteadas para los espacios rurales, y cuáles son los temas abordados. Los resultados evidencian que, al contrario de lo que cabría esperar, las CC.AA. predominantemente rurales no registran la mayor cantidad de actuaciones destinadas al medio rural, y que las temáticas sobre las que más se actúan atienden a la planificación y desarrollo territorial…
Oxidative stress in preterm infants: Overview of current evidence and future prospects
2020
Preterm birth (PTB), defined as parturition prior to 37 weeks of gestation, is the leading cause of morbidity and mortality in the neonatal population. The incidence and severity of complications of prematurity increase with decreasing gestational age and birthweight. The aim of this review study is to select the most current evidence on the role of oxidative stress in the onset of preterm complication prevention strategies and treatment options with pre-clinical and clinical trials. We also provide a literature review of primary and secondary studies on the role of oxidative stress in preterm infants and its eventual treatment in prematurity diseases. We conducted a systematic literature s…
Training for Work at the Margins of the Projective City
2020
Drawing upon the work by Boltanski and Chiapello and Boltanski and Thevenot, the training provision that is offered in Spain both to vulnerable youth and to socially excluded adults is analyzed here. It is too often the case that trainers in those programs work under temporary contracts. The reason for this is that the institutions they work for, often Non Governmental Organizations but also municipalities or trade unions, work under the so called projective city—i.e., a connectionist rationale. This fact has an impact upon the notion of work that these trainers portray to trainees attending their vocational training schemes, on-the-job training as well as guidance support. It is also the c…
Measure, category and learning theory
1995
Measure and category (or rather, their recursion theoretical counterparts) have been used in Theoretical Computer Science to make precise the intuitive notion “for most of the recursive sets.” We use the notions of effective measure and category to discuss the relative sizes of inferrible sets, and their complements. We find that inferrible sets become large rather quickly in the standard hierarchies of learnability. On the other hand, the complements of the learnable sets are all large.