1,720,992 research outputs found
Defect-Induced Magnetism in Graphene: An Ab Initio Study
No full textGraphene is an amazing two-dimensional system with exceptional physical and chemical properties. Potential applications in quantum information processing have been proposed for C-based materials, in particular for graphene system, where electron spin is a promising candidate for a solid-state qubit. The preservation of long spin coherence time is the fundamental feature to get for efficient working spin-qubit system. Despite graphene environment seems to suit the goal, defects in the structure, interactions with impurities and edge states can be a source of alteration of quantum information, since they could enhance the decoherence effects. The present work is a computational analysis of defective systems. It focuses on the investigations of various prototypical defect states (vacancies) and impurities interacting with graphene surface (hydrogen, boron, nitrogen, and oxygen) by means of density functional theory (DFT). We provide a preliminary study about the effects of these interactions. Vacancy-type defects give rise to a breaking of graphene symmetry, promoting a localized state with a magnetic moment whose magnitude is concentration-dependent. Hydrogen promotes a locally hybridization of the structure providing a localized magnetic moment and giving rise to an enhancement of spin-orbit interaction of about three orders of magnitude, showing the impact of hydrogen on spin-relaxation time. Among boron, nitrogen, and oxygen, the work has shown that the only one which returns a magnetic ground state is nitrogen. Boron
provides an n-doping of defective-graphene. Oxygen leads to a hybridization of carbon atoms bonding, but its electronic structure does not allow a magnetic system. In the particular case of a bridge-like adsorption site. Among the different configurations for the adsorption sites, the bridge-site is energetically the most stable one, showing as in the other configurations for nitrogen, a magnetic system. Nitrogen adatoms develop a magnetic order (at zero temperature) which is always ferromagnetic independently from the distance between two adjacent nitrogen atoms
Modelling of early-stage kilonova ejecta opacity reproducible in laboratory plasmas
Full text linkIn the framework of the multi-messenger astronomy, for a complete understanding of the heavy elements nucleosynthesis, investigation of the kilo- nova (KN) emission is crucial. The KN is a thermal transient signal following gravitational-wave events from the coalescence of compact objects. Modelling the KN light-curve is challenging: besides the difficulties in modelling the r-process synthesised elements, it requires several inputs, among which plasma ejecta opacity is still extremely uncertain. In this context, the PANDORA project aims at measuring, for the first time, opacities of a plasma resembling the plasma ejecta through which KN diffuses. In view of that, we present numerical estimates of argon plasma opacity perturbed by an external radiation flux under non local thermodynamic equilibrium. Simulations performed serve as demonstrator for further metallic elements, and their results underline that both thermodynamic parameters and radiation could impact on the opacity of the plasma
Euscarus cretensis: CARATTERIZZAZIONI D’ORDINE BROMATOLOGICO, ORGANOLETTICO, IGIENICO – SANITARIO, ISPETTIVO E VALUTAZIONE PRELIMINARE SULLA TRASFORMABILITA’ IN “KAMABOKO”
Full text link
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Predicting β-decay rates of radioisotopes embedded in anisotropic ECR plasmas
No full textStudying in-plasma decay rates as a function of ionic charge state distribution (CSD) is the fundamental objective of the PANDORA project. To this effect, we present here two theoretical models to calculate β-decay lifetimes of radionuclide ions embedded in an energetic electron cyclotron resonance (ECR) plasma, starting from anisotropic electron distributions. The first model -designed as separate modules to implement various atomic processes like electron-ion reactions, ion-ion charge exchange collisions and ion loss dynamics sequentially- serves as a predecessor to a more robust second model aimed at coupling ion population kinetics with complex transport phenomena in an ECR plasma. The outputs from the models -in the form of space-resolved CSD and level populations- can be fed to an appropriate code based on known theories connecting atomic level configurations to decay lifetime to calculate the position-dependent β-decay rate
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
