Unstable and elusive superconductors

We briefly review earlier and report original experimental results in the context of metastable or possible superconducting materials. We show that applied electric field induces conducting state in Copper Chloride (CuCl) whose characteristics resemble behavior of sliding charge-density-wave(s) (CDW). We discuss whether the sliding CDW or collective transport of similar ordered charge phase(s) may account for the problem of "high-temperature superconductivity" observed in this and other materials, including Cadmium Sulfide (CdS), metal-ammonia solutions, polymers, amorphous carbon and tungsten oxides. We also discuss a local superconductivity that occurs at the surface of graphite and amorphous carbon under deposition of foreign atoms/molecules.Comment: Invited review article published in a special edition on Superconducting Materials in honor of the 95th birthday year of Ted Geballe, edited by M. B. Maple, J. Hirsch, and F. Marsigli

Emprendimiento y economía gig: un análisis bibliométrico

[EN] There is an increasing number of academic publications on studying the impact of the gig economy and digital platforms. Some of them involve entrepreneurship and business models. However, there is a lack of a global picture depicting the scientific structure of knowledge regarding the gig economy and entrepreneurship. This paper presents a conceptual, intellectual, and social bibliometric overview, using Bibliometrix and Biblioshiny (R-packages). To this end, total of 345 published articles were analyzed, covering 245 sources, 44 countries and 751 authors. There are several important findings: five main clusters emerged from the study (Self-employment and social economy; Sharing economy and sustainable development; Entrepreneurship and innovation; Gig economy and platform economy; and Digitalization); the main themes that emerge deal with sharing, gig, and platform economy, digitalization, teleworking, career participation and platforms; finally, gig workers are key for developing strategies, policies, and actions to achieve a social welfare through entrepreneurship in the platform ecosystem. It is also important to highlight the role of communities and social capital in the development of sustainable collaborative initiatives through digital entrepreneurship.[ES] Existe un número cada vez mayor de publicaciones académicas sobre el estudio del impacto de la economía gig y las plataformas digitales. Algunos de ellos incluyen el espíritu emprendedor y el modelo de negocio. Sin embargo, como falta una imagen global que describa la estructura científica del conocimiento con respecto a la economía gig y el emprendimiento, este artículo presenta una descripción bibliométrica conceptual, intelectual y social, utilizando Bibliometrix y Biblioshiny (paquetes R). Para ello, analizó un total de 345 artículos, que abarcan 245 fuentes, 44 países y 751 autores. Hay varios hallazgos importantes: cinco grupos principales surgieron del estudio (Autoempleo y economía social; Economía compartida y desarrollo sostenible; Emprendimiento e innovación; Economía Gig y economía de plataformas; y Digitalización); los principales temas que surgen tratan sobre el intercambio, la economía gig y las plataformas, la digitalización, el teletrabajo, la participación profesional y las plataformas; finalmente, los trabajadores gig son clave para desarrollar estrategias, políticas y acciones para lograr un bienestar social a través del emprendimiento en el ecosistema de las plataformas digitales. También es importante destacar el papel de las comunidades y el capital social en el desarrollo de iniciativas colaborativas sostenibles a través del emprendimiento digital

El papel de la Pasión y la Autoeficacia en las actividades emprendedoras en la Economía gig: Un análisis de aprendizaje automático no supervisado con modelación temática

JEL: L26; M13; M15[EN] This research examines passion and self-efficacy through experience and knowledge, as motivational factors that support entrepreneurs within the gig economy (GE). It sheds light on entrepreneurs’ sources of passion in the GE literature. The sample is composed of all the 1164 entrepreneurship activities offered worldwide through Airbnb, Tour by Locals, and Withlocals on 5 May 2022. The study is supported by unsupervised machine learning models and seeks to find latent topics emerging from the analysis of the entrepreneurs’ descriptions and exposes the main correlated clustered dimensions. There are six main motivators behind GE platforms as a first step toward entrepreneurship: Experience, Passion for share, Knowledge, Classic traditions, Empowered community and local activities, and Well-being. It also confirms the correlation between passion and self-efficacy through experience, pointing them as main factors behind entrepreneurship in the GE. Five of the six sources of passion previously pointed by theory were found: Passion for growth, for people, for product/service, for innovation and for social mission. This study discloses self-efficacy and the sources of passion and points directions to practitioners involved in entrepreneurial activities in the GE ecosystem. This work used machine learning models to access quantitatively a paradigm that is inductive by nature. The results point to well-being as a significant factor to be addressed in future research regarding entrepreneurship. This research only studies individuals involved in the GE; as such, further studies should cohort new populations from different fields.[ES] Esta investigación examina la pasión y la autoeficacia a través de la experiencia y el conocimiento, como factores motivacionales que apoyan a los emprendedores dentro de la economía gig (EG). Crea nuevas sobre las fuentes de pasión de los emprendedores en la literatura de la EG. La muestra se compone de todas las 1.164 actividades de emprendimiento ofrecidas en Airbnb, Tour by Locals y Withlocals el cinco de Mayo de 2022. El estudio se apoya en modelos de aprendizaje automático no supervisado trata de encontrar temas latentes que emergen del análisis de las descripciones de esos emprendedores y expone las principales dimensiones agrupadas correlacionadas. Hay seis motivadores principales detrás de las plataformas de EG como primer paso hacia el emprendimiento: Experiencia, Pasión por compartir, Conocimiento, Tradiciones clásicas, Empoderamiento de la comunidad y actividades locales, y Bienestar. También se confirma la correlación entre la pasión y la autoeficacia a través de la experiencia, señalándolas como factores principales detrás del espíritu empresarial en la EG. Se encontraron cinco de las seis fuentes de pasión señaladas anteriormente por la teoría: Pasión por el crecimiento, por las personas, por el producto/servicio, por la innovación y por la misión social. Este trabajo revela la autoeficacia y las fuentes de pasión y señala direcciones a los profesionales implicados en actividades emprendedoras en el ecosistema de la EG. Este trabajo utilizó modelos de aprendizaje automático para acceder cuantitativamente a un paradigma que es inductivo por naturaleza. Los resultados apuntan al bienestar como un factor significativo que debe abordarse en futuras investigaciones sobre el espíritu empresarial. Esta investigación sólo estudia individuos involucrados en la EG; como tal, estudios posteriores deberían cohortar nuevas poblaciones de diferentes ámbitos.This work was financially supported by the Research Unit on Governance, Competitiveness and Public Policies (UIDB/04058/2020), funded by national funds through FCT – Fundação para a Ciência e a Tecnologia

Chitosan nanoparticles for daptomycin delivery in ocular treatment of bacterial endophthalmitis

Context: Chitosan nanoparticles were prepared to encapsulate daptomycin and proposed as a delivery system of this antibiotic to the eye for the treatment of bacterial endophthalmitis. Objective: The aim of this study was to develop daptomycin-loaded nanoparticles to apply directly to the eye, as a possible non-invasive and less painful alternative for the treatment of endophthalmitis, increasing the effectiveness of treatment and reducing toxicity associated with systemic administration.Materials and methods: Nanoparticles were obtained by ionotropic gelation between chitosan and sodium tripolyphosphate (TPP). Physicochemical and morphological characteristics of nanoparticles were evaluated, as well as determination of antimicrobial efficiency of encapsulated daptomycin and stability of the nanoparticles in the presence of lysozyme and mucin.Results: Loaded nanoparticles presented mean particle sizes around 200 nm, low polydispersity index, and positive zeta potential. Morphological examination by scanning electron microscopy (SEM) confirmed their small size and round-shaped structure. Encapsulation efficiency ranged from 80 to 97%. Total in vitro release of daptomycin was obtained within 4 h. Determination of minimum inhibitory concentrations (MICs) showed that bacteria were still susceptible to daptomycin encapsulated into the nanoparticles. Incubation with lysozyme did not significantly affect the integrity of the nanoparticles, although mucin positively affected their mucoadhesive properties. Discussion and conclusion: The obtained nanoparticles have suitable characteristics for ocular applications, arising as a promising solution for the topical administration of daptomycin to the eye.info:eu-repo/semantics/publishedVersio

PEGylated cationic liposome - DNA nanoparticle assembly in cell culture media: pathway effects and clues to enhanced control and transfection efficiency optimization

XII Spanish-Portuguese Conference on Controlled Drug DeliveryCationic Liposome – DNA nanoparticles constitute a promising approach for safe and efficient delivery of genes for therapeutic applications. In order to be used in vivo, these particles can be coated with an inert and hydrophilic polymer, such as polyethylene-glycol (PEG), which improves blood circulation time by providing steric stabilization against removal by the immune system. In this work we study the influence of the initial salt concentration, which controls the electrostatic atraction between cationic liposomes and anionic DNA, on the structure of PEGylated CL–DNA nanoparticles.info:eu-repo/semantics/publishedVersio

The Electromagnetic Form Factor of the Kaon in the Light-Front Approach

The kaon electromagnetic form factor is calculated within a light-front constituent quark model (LFCQM). The electromagnetic components of the current are extracted from the Feynman triangle diagram within the light-front approach. We also obtain the electroweak decay constant and the charge radius for the kaon in the light-front approach. In this work, the kaon observables are calculated and a fairly good agreement is obtained with a very higher accuracy when compared with the experimental data.Comment: Paper with 4 pages, 1 figure, reference: XII HADRON PHYSICS Conference - to appear in AIP Conference Proceeding

Structural MRI texture analysis for detecting Alzheimer's disease

Purpose:: Alzheimer’s disease (AD) has the highest worldwide prevalence of all neurodegenerative disorders, no cure, and low ratios of diagnosis accuracy at its early stage where treatments have some effect and can give some years of life quality to patients. This work aims to develop an automatic method to detect AD in 3 different stages, namely, control (CN), mild-cognitive impairment (MCI), and AD itself, using structural magnetic resonance imaging (sMRI). Methods:: A set of co-occurrence matrix and texture statistical measures (contrast, correlation, energy, homogeneity, entropy, variance, and standard deviation) were extracted from a two-level discrete wavelet transform decomposition of sMRI images. The discriminant capacity of the measures was analyzed and the most discriminant ones were selected to be used as features for feeding classical machine learning (cML) algorithms and a convolution neural network (CNN). Results:: The cML algorithms achieved the following classification accuracies: 93.3% for AD vs CN, 87.7% for AD vs MCI, 88.2% for CN vs MCI, and 75.3% for All vs All. The CNN achieved the following classification accuracies: 82.2% for AD vs CN, 75.4% for AD vs MCI, 83.8% for CN vs MCI, and 64% for All vs All. Conclusion:: In the evaluated cases, cML provided higher discrimination results than CNN. For the All vs All comparison, the proposedmethod surpasses by 4% the discrimination accuracy of the state-of-the-art methods that use structural MRI.info:eu-repo/semantics/publishedVersio

Contributions of neuromarketing to design

The reported study aims to assign different perspectives for reflection; to consider how neuromarketing can assist in understanding consumer behavior, intending to investigate the best way to develop products and improve communication through neuroscience. The systematic literature review referred here applies as a scientific method of research and analysis in a specific area of science. Following the PRISMA guidelines (2009), the research was carried out in March and April 2020, in seven electronic databases for the inclusion of quantitative, qualitative, or mixed studies published in Portuguese or English, master's or doctoral theses and research reports that focused in neuromarketing. One hundred and fifty studies were conducted, 20 of which, met the inclusion criteria. 1st filter: title, abstract, keywords and references; 2nd filter: introduction and conclusion of studies; 3rd filter: full reading of the studies (Liberati et al., 2009).This work is financed by portuguese national funds through FCT - Fundação para a Ciência e Tecnologia, under the project UIDB/05422/2020info:eu-repo/semantics/publishedVersio