3,044 research outputs found

    Spontaneous Magnetization through Non-Abelian Vortex Formation in Rotating Dense Quark Matter

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    When a color superconductor of high density QCD is rotating, superfluid vortices are inevitably created along the rotation axis. In the color-flavor locked phase realized at the asymptotically large chemical potential, there appear non-Abelian vortices carrying both circulations of superfluid and color magnetic fluxes. A family of solutions has a degeneracy characterized by the Nambu-Goldtone modes CP2, associated with the color-flavor locked symmetry spontaneously broken in the vicinity of the vortex. In this paper, we study electromagnetic coupling of the non-Abelian vortices and find that the degeneracy is removed with the induced effective potential. We obtain one stable vortex solution and a family of metastable vortex solutions, both of which carry ordinary magnetic fluxes in addition to color magnetic fluxes. We discuss quantum mechanical decay of the metastable vortices by quantum tunneling, and compare the effective potential with the other known potentials, the quantum mechanically induced potential and the potential induced by the strange quark mass.Comment: 24 pages, 4 figures; v2 revised published versio

    Il Physiologus nel Liber de natura rerum di Tommaso di Cantimpré

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    Nel Prologus al suo Liber de natura rerum (1225 ca.-1260 ca.), il domenicano Tommaso di Cantimpré elenca le 15 fonti principali del suo lavoro. Al penultimo posto di tale lista, egli pone il Physiologus, descrivendolo come come un’auctoritas “abbastanza succinta e utile in diverse occasioni”. Partendo da questa indicazione, il presente articolo indaga quindi due aspetti di questo rapporto, ovvero come e quanto il trattatello di origine alessandrina è effettivamente usato nell’enciclopedia domenicana, e quale versione di tale fonte era sul tavolo di lavoro tommasiano durante la stesura del Liber.In the Prologus to his Liber de natura rerum (1225 ca.-1260 ca.), the Dominican Thomas of Cantimpré lists the 15 sources he used most during the writing of the encyclopedia. In the penultimate place on this list, he puts the Physiologus and describes it as an auctoritas “quite succinct and useful on several occasions”. Starting from this indication, the present article investigates therefore two aspects of this relationship. First, how and how much the Alexandrian treatise is actually used in the Dominican encyclopedia. Second, what version of this didactic work was on Thomas’ desk during the drafting of the Liber.Dans le Prologue de son Liber de natura rerum (1225 ca.-1260 ca.), le dominicain Thomas de Cantimpré énumère les quinze sources qu'il a le plus utilisées lors de la rédaction de l'encyclopédie. À l'avant-dernière place de cette liste, il place le Physiologus qu'il décrit comme une auctoritas « assez succincte, et utile à plusieurs reprises ». A partir de cette indication, le présent article étudie deux aspects de cette relation. D'abord, comment et dans quelle mesure le traité alexandrin est effectivement utilisé dans l'encyclopédie dominicaine ; en second lieu, quelle version de cette œuvre didactique se trouvait sur le bureau de Thomas lors de la rédaction du Liber

    Laser irradiated foam targets: absorption and radiative properties

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    An experimental campaign to characterize the laser radiation absorption of foam targets and the subsequent emission of radiation from the produced plasma was carried out in the ABC facility of the ENEA Research Center in Frascati (Rome). Different targets have been used: plastic in solid or foam state and aluminium targets. The activated different diagnostics allowed to evaluate the plasma temperature, the density distribution, the fast particle spectrum and the yield of the X-Ray radiation emitted by the plasma for the different targets. These results confirm the foam homogenization action on laser-plasma interaction, mainly attributable to the volume absorption of the laser radiation propagating in such structured materials. These results were compared with simulation absorption models of the laser propagating into a foam target

    Simultaneous observation of ultrafast electron and proton beams in TNSA

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    The interaction of ultra-intense high-power lasers with solid-state targets has been largely studied for the past 20 years as a future compact proton and ion source. Indeed, the huge potential established on the target surface by the escaping electrons provides accelerating gradients of TV/m. This process, called target normal sheath acceleration, involves a large number of phenomena and is very difficult to study because of the picosecond scale dynamics. At the SPARC_LAB Test Facility, the high-power laser FLAME is employed in experiments with solid targets, aiming to study possible correlations between ballistic fast electrons and accelerated protons. In detail, we have installed in the interaction chamber two different diagnostics, each one devoted to characterizing one beam. The first relies on electro-optic sampling, and it has been adopted to completely characterize the ultrafast electron components. On the other hand, a time-of-flight detector, based on chemical-vapour-deposited diamond, has allowed us to retrieve the proton energy spectrum. In this work, we report preliminary studies about simultaneous temporal resolved measurements of both the first forerunner escaping electrons and the accelerated protons for different laser parameters

    The Promotoer, a brain-computer interface-assisted intervention to promote upper limb functional motor recovery after stroke: a statistical analysis plan for a randomized controlled trial

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    Background: Electroencephalography (EEG)-based brain-computer interfaces (BCIs) allow to modulate the sensorimotor rhythms and are emerging technologies for promoting post-stroke motor function recovery. The Promotoer study aims to assess the short and long-term efficacy of the Promotoer system, an EEG-based BCI assisting motor imagery (MI) practice, in enhancing post-stroke functional hand motor recovery. This paper details the statistical analysis plan of the Promotoer study. Methods: The Promotoer study is a randomized, controlled, assessor-blinded, single-centre, superiority trial, with two parallel groups and a 1:1 allocation ratio. Subacute stroke patients are randomized to EEG-based BCI-assisted MI training or to MI training alone (i.e. no BCI). An internal pilot study for sample size re-assessment is planned. The primary outcome is the effectiveness of the Upper Extremity Fugl-Meyer Assessment (UE-FMA) score. Secondary outcomes include clinical, functional, and user experience scores assessed at the end of intervention and at follow-up. Neurophysiological assessments are also planned. Effectiveness formulas have been specified, and intention-to-treat and per-protocol populations have been defined. Statistical methods for comparisons of groups and for development of a predictive score of significant improvement are described. Explorative subgroup analyses and methodology to handle missing data are considered. Discussion: The Promotoer study will provide robust evidence for the short/long-term efficacy of the Promotoer system in subacute stroke patients undergoing a rehabilitation program. Moreover, the development of a predictive score of response will allow transferring of the Promotoer system to optimal clinical practice. By carefully describing the statistical principles and procedures, the statistical analysis plan provides transparency in the analysis of data. Trial registration: ClinicalTrials.gov NCT04353297 . Registered on April 15, 2020
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