Equilibrium currents in a Corbino graphene ring

We address the description of a graphene Corbino disk in the context of a tight binding approach that includes both kinetic and Rashba spin-orbit coupling due to an external out-of-plane electric field. Persistent equilibrium currents are induced by an external magnetic field breaking time reversal symmetry. By direct diagonalization, we compute the spectrum and focus on the dispersion near the $K$ points at the Fermi level. The dispersion keenly reproduces that of a continuum model in spite of the complexity of the boundary conditions. We validate the assumptions of the continuum model in terms of predominant zig-zag boundaries conditions and weak sub-band coupling. The wave functions displaying the lowest transverse modes are obtained, showing the predominance of edge states with charge density at the zig-zag edges. The persistent charge currents, nevertheless, do not follow the traditional argument of current cancellation from levels below the Fermi level, and thus they depart in the tight-binding from those found in the continuum model.Comment: 8 pages, 6 figure

Electrodynamic formulation of special relativity from the first postulate

This work presents the form that the special theory of relativity takes when only the first postulate and the properties of homogeneity and isotropy of space and time are considered valid. The transformations of Lorentz coordinates are obtained in terms of a universal constant parameter k, developing from these the relativistic kinematics, dynamics and electrodynamics and their respective invariances before these transformations

MAC-Oriented Programmable Terahertz PHY via Graphene-based Yagi-Uda Antennas

Graphene is enabling a plethora of applications in a wide range of fields due to its unique electrical, mechanical, and optical properties. In the realm of wireless communications, graphene shows great promise for the implementation of miniaturized and tunable antennas in the terahertz band. These unique advantages open the door to new reconfigurable antenna structures which, in turn, enable novel communication protocols at different levels of the stack. This paper explores both aspects by, first, presenting a terahertz Yagi-Uda-like antenna concept that achieves reconfiguration both in frequency and beam direction simultaneously. Then, a programmable antenna controller design is proposed to expose the reconfigurability to the PHY and MAC layers, and several examples of its applicability are given. The performance and cost of the proposed scheme is evaluated through full-wave simulations and comparative analysis, demonstrating reconfigurability at nanosecond granularity with overheads below 0.02 mm$^{2}$ and 0.2 mW.Comment: Accepted for presentation in IEEE WCNC '1

Technological and Human Development of Smart Cities: An Empirical Characterization of EUROCITIES Case Studies

Smart Cities are conceived as strategic models to confront the wicked problems that exist in urban contexts. The research literature, however, reflects a lack of consensus on the elements that make a city smart. While some authors focus on technological aspects, others consider human factors as principal targets of the cities’ initiatives. Aiming to shed light on this discrepancy and understand what makes a city smarter, in this paper, we analyze a large number of real case studies implemented in major European Smart Cities. From our analysis, we first characterize and categorize the cities according to theoretical Smart City models proposed in the literature. Based on the cities\u27 characteristics and categories, we then compare them according to external variables, such as their positions in worldwide Smart City rankings, and their administrative contexts

A Framework to Evaluate Software Developer’s Productivity The VALORTIA Project

Currently, there is a lack in companies developing software in relation to assessing their staff’s productivity before executing software projects, with the aim of improving effectiveness and efficiency. QuEF (Quality Evaluation Framework) is a framework that allows defining quality management tasks based on a model. The main purpose of this framework is twofold: improve an entity’s continuous quality, and given a context, decide between a set of entity’s instances on the most appropriate one. Thus, the aim of this paper is to make this framework available to evaluate productivity of professionals along software development and select the most appropriate experts to implement the suggested project. For this goal, Valortia platform, capable of carrying out this task by following the QuEF framework guidelines, is designed. Valortia is a platform to certify users' knowledge on a specific area and centralize all certification management in its model by means of providing protocols and methods for a suitable management, improving efficiency and effectiveness, reducing cost and ensuring continuous quality.Ministerio de Ciencia e Innovación TIN2013-46928-C3-3-

Analyzing Citizen Participation and Engagement in European Smart Cities

With the advent of smart cities (SCs), governance has been placed at the core of the debate on how to create public value and achieve a high quality of life in urban environments. In particular, given that public value is rooted in democratic theory and new technologies that promote networking spaces have emerged, citizen participation represents one of the principal instruments to make government open and close to the citizenry needs. Participation in urban governance has undergone a great development: from the first postmodernist ideals of countering expert dominance to today’s focus on learning and social innovation, where citizen participation is conceptualized as co-creation and co-production. Despite this development, there is a lack of research to know how this new governance context is taking place in the SC arena. Addressing this situation, in this article, we present an exhaustive survey of the research literature and a deep study of the experience in participative initiatives followed by SCs in Europe. Through an analysis of 149 SC initiatives from 76 European cities, we provide interesting insights about how participatory models have been introduced in the different areas and dimensions of the cities, how citizen engagement is promoted in SC initiatives, and whether the so-called creative SCs are those with a higher number of projects governed in a participatory wayThis work was supported by the Spanish Ministry of Economy, Industry and Competitiveness (TIN2016-80630-P), and the Spanish Ministry of Culture and Sport (CAS18/00035

Business Climate: When Weakness Means Foreign Direct Divestment

This chapter is about weak business climate as a cause for foreign direct divestment. The aim is to show the connection between a poor business climate and foreign direct divestment. The methodology used entails a review of the different factors of the business climate such as the ease to do business, corruption, and rule of law. A review of the UNCTAD foreign direct investment flow as compared to the business climate indicators to determine a pattern is also part of the methodology. The chapter highlights the externalities of foreign direct divestment and suggests some ideas to overcome the global negative impact of foreign direct divestment as it is estimated to be significant in the aftermath of the COVID-19 pandemic. The conclusion is that foreign direct divestments can occur for different factors, some internal and some external. Weak business climates seem to play a role in a decision to divest an investment but there is no direct correlation