Landauer-B\"uttiker Study of the Anomalous Hall Effect

We report on Landauer-B\"uttiker studies of anomalous Hall transport in a two-dimensional electron gas with Rashba spin-orbit coupling and a magnetization provided by localized magnetic moments. Our system is described by a discretized tight-binding model in a four-terminal geometry. We consider both the case of magnetically disordered systems as well as ballistic transport in disorder-free systems with spatially homoge- neous magnetization. In the latter case we investigate both out-of-plane and in-plane magnetizations. We numerically establish a close connection between singularities in the density of states and peaks in the Hall conductance close to the lower band edge. Consistent with previous theoretical studies based on diagrammatic perturbation expansions, these peaks occur at Fermi energies where only the lower dispersion branch is occupied. Moreover, for large magnetization the Hall conductance is, along with the density of states, sup- pressed. This numerical finding can be understood from analytical properties of the underlying model in the limit of an infinite system.Comment: 10 pages, 13 figures. Published Phys. Rev. B 80, 155321 (2009

Buckyball Quantum Computer: Realization of a Quantum Gate

We have studied a system composed by two endohedral fullerene molecules. We have found that this system can be used as good candidate for the realization of Quantum Gates Each of these molecules encapsules an atom carrying a spin,therefore they interact through the spin dipole interaction. We show that a phase gate can be realized if we apply on each encased spin static and time dependent magnetic field. We have evaluated the operational time of a $\pi$-phase gate, which is of the order of ns. We made a comparison between the theoretical estimation of the gate time and the experimental decoherence time for each spin. The comparison shows that the spin relaxation time is much larger than the $\pi$-gate operational time. Therefore, this indicates that, during the decoherence time, it is possible to perform some thousands of quantum computational operations. Moreover, through the study of concurrence, we get very good results for the entanglement degree of the two-qubit system. This finding opens a new avenue for the realization of Quantum Computers.Comment: 13 pages, 5 figures. Submitted to Physical Review

Fast Quantum Computing with Buckyballs

We have found that encapsulated atoms in fullerene molecules, which carry a spin, can be used for fast quantum computing. We describe the scheme for performing quantum computations, going through the preparation of the qubit state and the realization of a two-qubit quantum gate. When we apply a static magnetic field to each encased spin, we find out the ideal design for the preparation of the quantum state. Therefore, adding to our system a time dependent magnetic field, we can perform a phase-gate. The operational time related to a $\pi-$phase gate is of the order of $ns$. This finding shows that, during the decoherence time, which is proportional to $\mu s$, we can perform many thousands of gate operations. In addition, the two-qubit state which arises after a $\pi-$gate is characterized by a high degree of entanglement. This opens a new avenue for the implementation of fast quantum computation.Comment: 9 pages, 4 figure

Docosahexaenoic acid promotes photoreceptor differentiation without altering Crx expression

PURPOSE: The precise molecular cues required for photoreceptor development are still unknown. Pax6 and Crx are essential during early retinal development and for photoreceptor differentiation, respectively. The lipid molecule docosahexaenoic acid (DHA) has also been shown to promote photoreceptor differentiation. Pax6 expression during the early steps in photoreceptor development and whether the mutual contribution of Crx and DHA enhances photoreceptor differentiation were investigated. METHODS: Neuroblast proliferation, Crx, and Pax6 expression were investigated in rat retinas in vivo and in neuronal cultures with or without DHA. BrdU incorporation, nestin and opsin expression, apical differentiation, and axonal outgrowth were determined by phase microscopy and immunochemistry. RESULTS: Pax6 expression occurred in all proliferating retinal neuroblasts in vivo; however, after their last mitotic division, photoreceptors stopped expressing Pax6 and started expressing Crx. In vitro, photoreceptor progenitors also showed a switch from Pax6 to Crx expression immediately after they exited the cell cycle and started differentiation. In contrast, those progenitors differentiating into amacrine neurons continued expressing Pax6 and did not express Crx. Most postmitotic photoreceptors expressing Crx showed little axon development and few of them expressed opsin. The addition of DHA dramatically increased differentiation in Crx-positive photoreceptors, enhancing opsin expression, apical differentiation, and axonal outgrowth, without affecting Crx expression. CONCLUSIONS: The results suggest that Pax6 and Crx expression are mutually exclusive during photoreceptor differentiation. Onset of Crx expression may provide a permissive stage that is essential to initiate photoreceptor differentiation, but additional support of DHA, among other environmental signals, is necessary to accomplish further differentiation.Fil: Garelli, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Rotstein, Nora Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Politi, Luis Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentin

A Comprehensive Mixed-Mode Time-Domain Load- and Source-Pull Measurement System

We present a novel test set devised for nonlinear balanced device characterization using load-pull techniques. The system is capable of measuring the voltage and current waveforms at the calibration reference planes while independently tuning the device under test (DUT) source and load differential- and common-mode terminations. The test set is designed to address present and future large-signal multiport measurement needs, easing the characterization task while developing new multiport active device

Flexible Catholicism, Religion and the Church: The Italian Case

What is taking place in the religious field in some Western societies not only seems to reflect a crisis situation or irreversible decline in the church and dominant religious institutions. More than might be imagined, advanced modernity offers opportunities for traditional religions, even within a context fraught with contradictions and ambivalence. An example of this is represented by Italy, which is still today characterized by widespread affiliation to Catholicism, despite the increase in religious pluralism and undisputed secularization in the customs of the population. Comparing surveys carried out in 1994 and 2007 on a sample of the Italian population, the paper presents a version of religious modernity that has emerged both on the individual religious front and in the way religion is considered in the public sphere

The report on the promotion and protection of human rights in the context of climate change. A pragmatic analysis

Il contributo analizza criticamente il contenuto del rapporto sulla promozione e la protezione dei diritti umani nel contesto dei cambiamenti climatici adottato il 26 luglio 2022 dal Relatore speciale Ian Fry. In particolare, il documento esamina tre questioni chiave: il rapporto tra le azioni di mitigazione e gli obblighi degli stati sui diritti umani; le perdite e i danni da cambiamento climatico; la partecipazione ai processi decisionali e la protezione dei difensori dei diritti climatici.The paper critically analyses the report on the promotion and protection of human rights in the context of climate change adopted on 26 July 2022 by Special Rapporteur Ian Fry. In particular, the article explores three key issues: the relationship between mitigation actions and human rights obligations; climate change loss and damage and participation in decision-making processes and the protection of climate rights defenders

La Danza di Luciano : dagli artifici dell’elogio parodico ai dibattiti contemporanei sull'identità greca.

International audienceSi l’authenticité du Peri orchèseos de Lucien a pu être mise en doute à plusieurs reprises, ce n’était pas pour des raisons linguistiques mais pour des raisons liées aux difficultés de lecture et d’interprétation, au XXe siècle, d’un texte à la tonalité ambiguë, longtemps considéré comme un éloge sérieux de la pantomime. Cette communication dégage les aspects parodiques, ironiques, voire burlesques du texte, pour s’interroger sur les intentions de l’auteur : Lucien a-t-il simplement écrit un éloge artificiel et comique, ou posait-il à sa manière, en 163 ap. J.-C. des questions fondamentales touchant à l’identité et à la culture grecque ? L’enquête est menée sur la base d’une confrontation avec d’autres oeuvres de Lucien, mais aussi avec les testes théoriques de musique, d’athlétisme et de gymnastique de périodes antérieures et postérieures à Lucien (Dion de Pruse, pseudo-Plutarque, Aristide Quintilien, Galien, Philostrate…). Sur un mode humoristique et parodique, Lucien pose les questions liées à l’entraînement et à l’exhibition du corps et reflète les débats contemporains sur la préservation du passé et les valeurs de l’hellénisme.Se l’autenticità del peri orchèseos di Luciano ha potuto essere messa in dubbio a più riprese, non è stato per ragioni linguistiche, ma per difficoltà di lettura e di interpretazione, nel XX secolo, di un testo di tonalità ambigua, a lungo considerato come un elogio serio della pantomima. Questa comunicazione sviluppa gli aspetti parodici, ironici, se si vuole anche burleschi del testo, per interrogarsi sulle intenzioni dell'autore : Luciano avrebbe davvero scritto semplicemente un elogio artificioso e comico, oppure poneva, a modo suo, nel 163 dopo Cristo, problemi fondamentali concernenti l'identità e la cultura greca ? L’indagine è condotta sulla base di un confronto con le altre opere di Luciano, ma anche con i testi teorici ( i trattati ?) di musica, di atletica, di ginnastica di periodi anteriori e posteriori a Luciano (Dione de Prusia, pseudo-Plutarco, Aristide Quintiliano, Galieno, Filostrato). In maniera umoristica e parodica, Luciano presenta i problemi legati legati alla cura e all'esibizione del corpo e riflette l'eco dei dibattiti a lui contemporanei sulla salvaguardia del passato e sui valori dell'ellenismo

Commissioning of the ATLAS Pixel Detector

The ATLAS Pixel Detector is the innermost detector of the ATLAS experiment at LHC. Approximately 80 million silicon sensors allow to detect particle tracks and secondary vertices with very high precision. The ATLAS Pixel Detector is now in its final commissioning phase. A full characterization and qualification of the detector is currently performed: calibration procedures, special DAQ runs for noise studies and combined operations with other ATLAS subdetectors using cosmic-ray events are ongoing. All the aspects of the detector operation including the DAQ system, the calibration procedures, and the first cosmic run results are summarized

La praetexta à Rome : une autre réception de la tragédie grecque

sous la direction de B. Le GuenInternational audienceDans un ouvrage consacré aux notions de culture et d’identité nationale des Romains à l’époque républicaine, E. Gruen a insité sur l’interprétation qu’il convient de donner à la relation entre théâtre latin et culture grecque. L’affirmation aristocratique d’une maîtrise du système théâtral et des ludi était essentielle, mais elle ne passait pas nécessairement par les pièces elles-mêmes, c’est-à-dire par l’explicite d’un texte. La tragédie prétexte faisait-elle exception ? Le genre n’était pas, selon nous, un simple moyen d’autocélébration aux mains de l’aristocratie, mais une forme systématisée de la célébration nationale et patriotique d’un événement historique, conformément à l’usage qui devait être l’usage grec depuis des siècles. Dans ce cadre, l’importation d’éléments de la culture grecque ne fait plus de Rome un réceptacle passif de la culture grecque. Il convient plutôt de parler d’une réception active et de choix littéraires maîtrisés, qu’il s’agisse de tragédies mythologiques ou de tragédies historiques. L’hellénisation dans le domaine dramatique serait bien intéressante à étudier si nous disposions, justement, de textes des tragédies prétextes ou historiques