Majorana bound states in open quasi-1D and 2D systems with transverse Rashba coupling

We study the formation of Majorana states in quasi-1D and 2D square lattices with open boundary conditions, with general anisotropic Rashba coupling, in the presence of an applied Zeeman field and in the proximity of a superconductor. For systems in which the length of the system is very large (quasi-1D) we calculate analytically the exact topological invariant, and we find a rich phase diagram which is strongly dependent on the width of the system. We compare our results with previous results based on a few-band approximation. We also investigate numerically open 2D systems of finite length in both directions. We use the recently introduced generalized Majorana polarization, which can locally evaluate the Majorana character of a given state. We find that the formation of Majoranas depends strongly on the geometry of the system and if the length and the width are comparable no Majorana states can form, however, one can show the formation of "quasi-Majorana" states that have a local Majorana character, but no global Majorana symmetry.Comment: 12 pages, 13 figure

Classroom quality and children's social skills and problem behaviors: dosage and disability status as moderators

Multiple studies have reported associations between early childhood education (ECE) quality and dosage and children’s social and behavior development, with some suggesting that this association may be stronger for specific groups of children. In this study, we examined the association between classroom quality and children’s social skills and problem behaviors, as reported by ECE teachers, as well as the moderating effects of ECE dosage and children’s disability status. Participants were 222 children (Mage = 63.75, SD = 7.77), including 180 typically developing (90 boys) and 42 children with disabilities (29 boys), from 44 inclusive classrooms in the Metropolitan Area of Lisbon, Portugal. Our results indicated that children’s social skills and behavior problems were not directly associated with observed classroom quality domains. However, lower classroom organization predicted lower social skills and higher externalizing behavior at higher number of months with the lead teacher; and instructional support predicted increased social skills for children with disabilities. Days absent from school predicted lower social skills. Overall, our results suggest that diverse types of dosage influence teacher’s reports of social and behavioral outcomes in different ways.info:eu-repo/semantics/acceptedVersio

Flat Majorana bands in 2-d lattices with inhomogeneous magnetic fields: topology and stability

In this paper we show that for a range of configurations of inhomogeneous magnetic fields it is possible to create flat bands of Majorana states localized on the edges of 2-d lattices. Majorana bound states have been predicted to exist in both one dimensional and two dimensional systems with Rashba spin-orbit coupling, magnetic fields, and placed in proximity to a superconductor. For the proposed systems we present the bulk topological phase diagrams, and we study the conditions for weak topology which predicts the formation of bands of Majorana states. The Majorana bands are demonstrated to be relatively stable with respect to a variety of different perturbations on both square and hexagonal lattices.Comment: 13 pages, 17 figure

Teachers’ ideas about children’s participation within Portuguese early childhood education settings

This study investigated teachers’ ideas about children's right to participate in ECE. Participants were 59 teachers, aged between 26 and 60 years old (M = 43.07 years, SD = 8.58), all female, from 59 ECE classrooms from 24 randomly selected ECE centres located in the metropolitan area of Lisbon. Teacher's ideas were collected using a qualitative interview specifically designed for the purpose. Based on content analysis, multiple correspondence analysis, and cluster analysis, we identified profiles of teachers’ ideas and clusters of teachers. Results suggest four teacher profiles: Teachers motivation, Teachers’ conditioned responsibility, Children's benefits, and Context dependent. Profiles were significantly associated with years of professional experience and type of institution. Teachers’ age was significantly different across profiles. Findings provide insights to fuller understand teachers’ positioning about this right.info:eu-repo/semantics/acceptedVersio

Reproduction ratio and growth rates: Measures for an unfolding pandemic

The initial exponential growth rate of an epidemic is an important measure that follows directly from data at hand, commonly used to infer the basic reproduction number. As the growth rates λ(t) of tested positive COVID-19 cases have crossed the threshold in many countries, with negative numbers as surrogate for disease transmission deceleration, lock- downs lifting are linked to the behavior of the momentary reproduction numbers r(t), often called R0. Important to note that this concept alone can be easily misinterpreted as it is bound to many internal assumptions of the underlying model and significantly affected by the assumed recovery period. Here we present our experience, as part of the Basque Coun- try Modeling Task Force (BMTF), in monitoring the development of the COVID-19 epidemic, by considering not only the behaviour of r(t) estimated for the new tested positive cases— significantly affected by the increased testing capacities, but also the momentary growth rates for hospitalizations, ICU admissions, deceased and recovered cases, in assisting the Basque Health Managers and the Basque Government during the lockdown lifting mea- sures. Two different data sets, collected and then refined during the COVID-19 responses, are used as an exercise to estimate the momentary growth rates and reproduction numbers over time in the Basque Country, and the implications of using those concepts to make deci- sions about easing lockdown and relaxing social distancing measures are discussed. These results are potentially helpful for task forces around the globe which are now struggling to provide real scientific advice for health managers and governments while the lockdown measures are relaxed.Marie Skłodowska-Curie grant agreement No 79249

The role of mild and asymptomatic infections on COVID-19 vaccines performance: A modeling study

Introduction: Different COVID-19 vaccine efficacies are reported, with remarkable effectiveness against severe disease. The so called sterilizing immunity, occurring when vaccinated individuals cannot transmit the virus, is still being evaluated. It is also unclear to what extent people with no symptoms or mild infection transmit the disease, and estimating their contribution to outbreaks is challenging. Objective: With an uneven roll out of vaccination, the purpose of this study is to investigate the role of mild and asymptomatic infections on COVID-19 vaccine performance as vaccine efficacy and vaccine coverage vary. Methods: We use an epidemiological SHAR (Susceptible-Hospitalized-Asymptomatic-Recovered) model framework to evaluate the effects of vaccination in different epidemiological scenarios of coverage and efficacy. Two vaccination models, the vaccine V1 protecting against severe disease, and the vaccine V2, protecting against infection as well as severe disease, are compared to evaluate the reduction of overall infections and hospitalizations. Results: Vaccine performance is driven by the ability of asymptomatic or mild disease cases transmitting the virus. Vaccines protecting against severe disease but failing to block transmission might not be able to reduce significantly the severe disease burden during the initial stage of a vaccination roll out programme, with an eventual increase on the number of overall infections in a population. Conclusion: The different COVID-19 vaccines currently in use have features placing them closer to one or the other of these two extreme cases, V1 and V2, and insights on the importance of asymptomatic infection in a vaccinated population are of a major importance for the future planning of vaccination programmes. Our results give insights on how to best combine the use of the available COVID-19 vaccines, optimizing the reduction of hospitalizations