Nonlinearities and Parametric Amplification in Superconducting Coplanar Waveguide Resonators

Experimental investigations of the nonlinear properties of superconducting niobium coplanar waveguide resonators are reported. The nonlinearity due to a current dependent kinetic inductance of the center conductor is strong enough to realize bifurcation of the nonlinear oscillator. When driven with two frequencies near the threshold for bifurcation, parametric amplification with a gain of +22.4 dB is observed.Comment: 4 pages, 5 figures, 1 table. In version 2: Added appendix with model description and fits to measurements. Minor corrections and rephrasin

Le bénévolat des jeunes

What makes young people want to learn, commit and become involved in an activity? This issue is of particular interest to teachers, but also to employers. In order to provide some answers, the authors of this book are interested in a specific population: young people aged 16 to 25 who have freely chosen to get involved in associations as varied as sport, politics, the environment, humanitarian work or events. Based on interviews, this study traces the volunteer careers of some forty young women and men from all social categories. They proudly recall the responsibilities that were entrusted to them very early on in a structured, flexible and benevolent associative world. Their testimonies help to highlight the many learning and skills that the volunteer experience has enabled them to develop

Towards a VR Evaluation Suite for Tactile Displays in Telerobotic Space Missions

Research and development of telerobotic systems supplemented by haptic feedback for future planetary exploration missions has gained significant importance in the past decade. Major space agencies endeavor to deploy such systems before sending humans to the surface of unknown or unexplored celestial bodies. Astronauts control these telerobotic systems from remote locations, such as an orbital space station. Haptic feedback for teleoperating the robots in outer space is extremely important, not only to improve user immersion and task performance, but also to improve our understanding of surface properties. At the same time, for spaceflight, making use of compact, light-weight and robust devices are preferred for precise tactile feedback from telemanipulation tasks. In this paper, we introduce "ViESTac", a first attempt to develop a generic VR suite to be able to evaluate and compare fingertip-wearable tactile devices. Applications of such a suite include, but are not limited to allowing teleoperators to judiciously choose suitable tactile devices for a particular task. To account for the wide variety of existing fingertip-wearable tactile devices and their display capabilities, the suite contains a set of virtual scenarios to investigate different tactile properties of virtual objects. It also dedicates a virtual scenario to evaluate how tactile feedback may govern the accuracy of human positioning in standard tasks. This proposed suite is advocated by a pilot study with 13 participants and two distinct state-of-the-art tactile devices. Results of the study clearly indicate that the virtual suite can successfully cater to the need of evaluating and comparing fingertip-wearable tactile devices

A manual and an automatic TERS based virus discrimination

Rapid techniques for virus identification are more relevant today than ever. Conventional virus detection and identification strategies generally rest upon various microbiological methods and genomic approaches, which are not suited for the analysis of single virus particles. In contrast, the highly sensitive spectroscopic technique tip-enhanced Raman spectroscopy (TERS) allows the characterisation of biological nano-structures like virions on a single-particle level. In this study, the feasibility of TERS in combination with chemometrics to discriminate two pathogenic viruses, Varicella-zoster virus (VZV) and Porcine teschovirus (PTV), was investigated. In a first step, chemometric methods transformed the spectral data in such a way that a rapid visual discrimination of the two examined viruses was enabled. In a further step, these methods were utilised to perform an automatic quality rating of the measured spectra. Spectra that passed this test were eventually used to calculate a classification model, through which a successful discrimination of the two viral species based on TERS spectra of single virus particles was also realised with a classification accuracy of 91%

Intervenções educativas para atividade física em adultos brasileiros: revisão sistemática

OBJETIVO: Sumarizar as principais evidências de intervenções educativas delineadas para o aumento dos níveis de atividade física (AF) em adultos brasileiros. MÉTODOS: Revisão sistemática de estudos de intervenção conduzidos no Brasil, que implementaram componentes educativos com a finalidade de promover o aumento dos níveis de AF em populações de adultos (18 a 65 anos). Em outubro de 2020, buscas sistemáticas foram conduzidas em seis bases de dados e nas listas de referências dos artigos avaliados. RESULTADOS: Dos 2.511 artigos iniciais, nove compuseram a síntese. Foram observadas amostras com características específicas (como vulnerabilidade social, inatividade física e sobrepeso ou obesidade), com maior número de mulheres. Cinco intervenções (55,6%) ocorreram nos cenários da atenção primária à saúde (APS) do Sistema Único de Saúde (SUS). Apenas em quatro estudos (44,4%) houve descrição dos referenciais pedagógicos estruturantes das abordagens educativas, dentro os quais o aconselhamento se configurou como a estratégia mais utilizada, como aquelas realizadas por meio de encontros presenciais, visitas domiciliares, palestras e chamadas telefônicas (n = 8; 88,9%). Resultados positivos foram observados em três distintos indicadores: aumento do volume semanal de AF (n = 4); aumento do índice de AF no lazer (n = 1); e aumento da proporção de mulheres classificadas como “muito ativas/ativas” (n = 1). Visto as especificidades amostrais, o domínio “seleção dos participantes” apresentou elevado número de intervenções com alto risco de viés. CONCLUSÕES: As abordagens educativas produziram alguns efeitos positivos em distintos indicadores de AF, destacando-se o aconselhamento como principal estratégia utilizada e as abordagens que envolveram outras temáticas de saúde, como nutrição e estresse. Contudo, frente aos diversos determinantes da AF no Brasil, é importante que futuras intervenções sejam conduzidas em variadas localizações do país, de forma que avaliem, de maneira mais ampla, seus processos de implementação e articulação com os distintos profissionais que atuam na APS.OBJECTIVE: To summarize the main evidence from educational interventions designed to increase levels of physical activity (PA) among Brazilian adults. METHODS: Systematic review of intervention studies carried out in Brazil that implemented educational components aimed at promoting increased levels of PA among adult populations (18 to 65 years old). In October 2020, systematic searches were conducted in six databases, and in the reference lists of the assessed studies. RESULTS: Of the initial 2,511 studies, nine were included in the synthesis. Samples with specific characteristics (such as social vulnerability, physical inactivity, and overweight or obesity) were observed, with a greater number of women. Five interventions (55.6%) occurred in primary healthcare settings (PHC) of the Brazilian Unified Health System (SUS). Only four studies (44.4%) described the pedagogical frameworks structuring the educational approaches, among which counseling was the most used strategy, such as those carried out through face-to-face meetings, home visits, lectures, and phone calls (n = 8; 88.9%). Positive results were observed in three different indicators: increase in weekly PA volume (n = 4); increase in leisure-time PA rate (n = 1); and increase in the proportion of women classified as “very active/active” (n = 1). Given the sampling specificities, the domain “participant selection” showed a high number of interventions with high risk of bias. CONCLUSIONS: Educational approaches engendered some positive effects on different PA indicators, notably counseling as the main strategy used and approaches involving other health themes, such as nutrition and stress. However, considering the several determinants of PA in Brazil, future interventions should be conducted in different locations of Brazil in order to evaluate, in a broader way, their implementation processes and articulation with the many professionals working in PHC

Biochemistry of the sphingolipides. X. Phytoglycolipide, a complex phytosphingosine‐containing lipide from plant seeds

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141721/1/aocs0335.pd

Strain-induced partially flat band, helical snake states, and interface superconductivity in topological crystalline insulators

Topological crystalline insulators in IV-VI compounds host novel topological surface states consisting of multi-valley massless Dirac fermions at low energy. Here we show that strain generically acts as an effective gauge field on these Dirac fermions and creates pseudo-Landau orbitals without breaking time-reversal symmetry. We predict the realization of this phenomenon in IV-VI semiconductor heterostructures, due to a naturally occurring misfit dislocation array at the interface that produces a periodically varying strain field. Remarkably, the zero-energy Landau orbitals form a flat band in the vicinity of the Dirac point, and coexist with a network of snake states at higher energy. We propose that the high density of states of this flat band gives rise to interface superconductivity observed in IV-VI semiconductor multilayers at unusually high temperatures, with non-BCS behavior. Our work demonstrates a new route to altering macroscopic electronic properties to achieve a partially flat band, and paves the way for realizing novel correlated states of matter.Comment: Accepted by Nature Physic