Turbulence Hierarchy in a Random Fibre Laser

Turbulence is a challenging feature common to a wide range of complex phenomena. Random fibre lasers are a special class of lasers in which the feedback arises from multiple scattering in a one-dimensional disordered cavity-less medium. Here, we report on statistical signatures of turbulence in the distribution of intensity fluctuations in a continuous-wave-pumped erbium-based random fibre laser, with random Bragg grating scatterers. The distribution of intensity fluctuations in an extensive data set exhibits three qualitatively distinct behaviours: a Gaussian regime below threshold, a mixture of two distributions with exponentially decaying tails near the threshold, and a mixture of distributions with stretched-exponential tails above threshold. All distributions are well described by a hierarchical stochastic model that incorporates Kolmogorov's theory of turbulence, which includes energy cascade and the intermittence phenomenon. Our findings have implications for explaining the remarkably challenging turbulent behaviour in photonics, using a random fibre laser as the experimental platform.Comment: 9 pages, 5 figure

Palaeohistology and palaeopathology of an Aeolosaurini (Sauropoda: Titanosauria) from Morro do Cambambe (Upper Cretaceous, Brazil)

Altres ajuts: CAISEP (Comisión de Ayudas a la Investigación de la Sociedad Española de Paleontología) project #2018-07153A recent publication of fossil bones of titanosaurs assigned to Aeolosaurini from the Morro do Cambambe site (Mato Grosso state, Brazil, Upper Cretaceous) reported anomalous growth in some of them. Here, we present osteohistological sections of elements to understand not only the microstructure and growth of such bones, but also the nature of those anomalies. The primary bone of all specimens consisted of a variation of the fibrolamellar complex, with the inner cortex being rich in woven bone with dispersed longitudinal canals, while the outer cortex was parallel-fibred with rows of longitudinal canals, interlayered by Lines of Arrested Growth (LAGs). We identified a maximum of two LAGs in the cervical rib and haemal arch, and four in the dorsal rib. The haemal arch shows an External Fundamental System (EFS) in most sections. The advanced remodelling and variation of the fibrolamellar bone in the cortex suggests that all the specimens represent individuals that reached sexual maturity. However, the haemal arch was distinct due to the wide distribution of EFS. The dorsal rib exhibited periosteal and endosteal outgrowth. Such microstructure was assigned to a reactive bone due to an intra-thoracic infection (a pneumonia, probably related to a tuberculosis), which is the first report in a non-avian dinosaur. The microstructure resembles the medullary bone recovered in dinosaurs, which suggests that further studies of medullary bone in thoracic bones should also regard the pathological cases.En una reciente publicación de los huesos fósiles de titanosaurios asignados al clado Aeolosaurini provenientes del yacimiento de Morro do Cambambe (estado de Mato Grosso, Brasil, Cretácico Superior), se reconocieron anormalidades en el crecimiento de algunos de ellos. En el presente trabajo presentamos cortes osteohistológicos de elementos para entender no sólo la microestructura y crecimiento de los mismos, sino también la naturaleza de aquellas anomalías. Entre ellos, seleccionamos una costilla cervical y una costilla dorsal media posterior, así como un arco hemal. El hueso primario de todos los especímenes comprendía una variación del complejo fibrolamelar, siendo la corteza interna rica en tejido reticular óseo con canales longitudinales dispersos, mientras que la corteza externa tenía fibras paralelas con hileras de canales longitudinales, intercaladas por líneas de crecimiento detenido. Identificamos un máximo de dos líneas de crecimiento detenido tanto en la costilla cervical como en el arco hemal, y cuatro en la costilla dorsal. El arco hemal muestra un Sistema Externo Fundamental en la mayoría de las secciones. La remodelación avanzada y la variación del hueso fibrolamelar en la corteza, se sugiere que todas los especímenes alcanzaron la madurez sexual. Sin embargo, el arco hemal fue distinto debido a la amplia distribución de Sistema Externo Fundamental. Con base en la microestructura, identificamos un semaforonte subadulto, y probablemente a un adulto. La costilla dorsal mostró una excrecencia perióstica y endosteal. Dicha microestructura se ha identificado con un hueso reactivo a una infección intratorácica (una neumonía, probablemente relacionada con una tuberculosis), que es el primer informe de un dinosaurio no aviano. La microestructura se asemeja al hueso medular recuperado en los dinosaurios, lo que sugiere que los estudios posteriores del hueso medular en los huesos torácicos también deberían considerar los casos patológicos

LaMMos - Latching Mechanism based on Motorized-screw for Reconfigurable Robots and Exoskeleton Suits

Reconfigurable robots refer to a category of robots that their components (individual joints and links) can be assembled in multiple configurations and geometries. Most of existing latching mechanisms are based on physical tools such as hooks, cages or magnets, which limit the payload capacity. Therefore, robots re- quire a latching mechanism which can help to reconfigure itself without sacrificing the payload capability. This paper presents a latching mechanism based on the flexible screw attaching principle. In which, actuators are used to move the robot links and joints while connecting them with a motorized-screw and dis- connecting them by unfastening the screw. The brackets used in our mechanism configuration helps to hold maximum force up to 5000N. The LaMMos - Latching Mechanism based on Motorized- screw has been applied to the DeWaLoP - Developing Water Loss Prevention in-pipe robot. It helps the robot to shrink its body to crawl into the pipe with minimum diameter, by recon- figuring the leg positions. And it helps to recover the legs positions to original status once the robot is inside the pipe. Also, LaMMos add stiffness to the robot legs by dynamically integrate them to the structure. Additionally, we present an application of the LaMMos mechanism to exoskeleton suits, for easing the mo- tors from the joints when carrying heavy weights for long periods of time. This mechanism offers many interesting opportunities for robotics research in terms of functionality, pay- load and size.Comment: 14 pages, 15 figure

Análise de curvas epidêmicas da Covid-19 via modelos generalizados de crescimento: Estudo de caso para as cidades de Recife e Teresina

Introduction: The Covid-19 pandemic is one of the biggest public health crises the world has ever faced. In this context, it is important to have effective models to describe the different stages of the epidemic’s evolution in order to guide the authorities in taking appropriate measures to fight the disease. Objective: To present an analysis of epidemic curves of Covid-19 based on phenomenological growth models, with applications to the curves for the cumulative numbers of confirmed cases of infection by the novel coronavirus (Sars-Cov-2) and deaths attributed to the disease (Covid-19) caused by the virus, for the Brazilian cities of Recife and Teresina. Methods: The Richards generalized model and the generalized growth model were used to make the numerical fits of the respective empirical curves. Results: The models used described very well the empirical curves against which they were tested. In particular, the generalized Richards model was able to identify the appearance of the inflexion point in the cumulative curves, which in turn represents the peak of the respective daily curves. A brief discussion is also presented on the relationship between the fitting parameters obtained from the model and the mitigation measures adopted in each of the municipalities considered. Conclusions: The generalized Richards model proved to be very effective in describing epidemic curves of Covid-19 and estimating important epidemiological parameters, such as the time of the peak of the curve for daily cases and deaths, thus allowing a practical and efficient monitoring of the epidemic evolution.Introdução: A pandemia da Covid-19 é uma das maiores crises de saúde pública que o mundo já enfrentou. Nesse contexto, é importante ter modelos eficazes para descrever os diferentes estágios da evolução da epidemia, a fim de orientar as autoridades competen- tes na adoção de políticas públicas para o enfrentamento da mesma. Objetivo: Apresentar uma análise de curvas epidêmicas com base em modelos fenomenológicos de crescimento, tomando como exemplo as curvas acumuladas de casos confirmados de infecção pelo novo coronavírus (Sars-Cov-2) e de óbitos atribuídos à doença (Covid-19) causada pelo vírus, para as cidades do Recife e Teresina. Métodos: Foram utilizados o modelo generalizado de Richards e o modelo de crescimento generalizado para fazer o ajuste numérico das respectivas curvas empíricas. Resultados: Verificou-se que os modelos utilizados descrevem muito bem as curvas empíricas em que foram testados. Em particular, o modelo generalizado de Richards é capaz de identificar com razoável confiabilidade o surgimento do ponto de infle- xão nas curvas acumuladas, o qual corresponde ao ponto de máximo das respectivas curvas diárias. Apresenta-se ainda uma breve discussão sobre a relação entre os parâmetros obtidos no ajuste do modelo e as medidas de mitigação adotadas para retardar a propagação da Covid-19 em cada um dos municípios considerados. Conclusões: O modelo generalizado de Richards mostrou-se bastante eficaz para descrever curvas epidêmicas da Covid-19 e es- timar parâmetros epidemiológicos importantes, como o pico das curvas de casos e óbitos diários, permitindo assim realizar de modo prático e eficiente o monitoramento da evolução da epidemia

PANORAMA DA COVID-19 NO NORDESTE BRASILEIRO: ANÁLISES E PREVISÕES VIA MODELOS DE CRESCIMENTO

The Covid-19 pandemic, caused by the new coronavirus (SARS-CoV-2), is one of the gravest public health crises the world has ever faced. In this context, it is important to have effective models to describe the different stages of the epidemic, in order to offer guidance to the competent authorities regarding the adoption of public policies to contain and control the pandemic. In this work, we present a novel method to analyze epidemic curves based on growth models, using as examples the cumulative curves of deaths attributed to Covid-19 for the states of the Northeastern Region of Brazil. Depending on the case, the q-exponential model, the Richards model or the generalized Richards model were used to make the numerical fits of the respective empirical curves. The models used here describe very well the empirical curves of all the Northeastern Brazilian States, thus allowing a more precise diagnosis of the stage of the epidemic in each of the States.  Among them, only the state of Paraíba is still in the early growth phase, when the epidemic curve does not yet have an inflexion point, being in this case better described by the q-exponential model.  The other states were better described either by the Richards model or by its generalized version. The Richards model, in particular, was able to identify with reasonable reliability the emergence of the inflexion point for states that only recently have reached this stage of the epidemic, such as Piauí, Rio Grande do Norte and Sergipe. This model is also able to predict when the inflection is about to occur, as is the case in Bahia. The generalized Richards model, in turn, has proved more appropriate to describe epidemic curves in states that are in a more developed phase of the epidemic, such as Ceará and Pernambuco, when the epidemic curves already show a more consolidated trend of saturation toward the plateau.A pandemia da Covid-19, causada pelo novo coronavírus (SARS-CoV-2), é uma das maiores crises de saúde pública que o mundo já enfrentou. Nesse contexto, é importante ter modelos eficazes para descrever os diferentes estágios da evolução da epidemia, a fim de orientar as autoridades competentes na adoção de políticas públicas para o enfrentamento e controle da pandemia. No presente trabalho, nós propomos um novo método de análise de curvas epidêmicas com base na seleção criteriosa de modelos de crescimento, tomando como exemplo as curvas acumuladas de óbitos atribuídos à Covid-19 para os estados da região Nordeste do Brasil. A depender do caso, foram utilizados o modelo q-exponencial, o modelo de Richards ou o modelo generalizado de Richards para fazer o ajuste numérico das respectivas curvas empíricas. Verificou-se que os modelos utilizados descrevem muito bem as curvas empíricas de todos os estados do Nordeste, permitindo assim diagnosticar mais precisamente o estágio da epidemia em cada um dos estados. Dentre eles, apenas o estado da Paraíba ainda encontra-se na fase inicial de crescimento, quando a curva epidêmica ainda não apresenta um ponto de inflexão, sendo nesse caso melhor descrita pelo modelo q-exponencial. Os demais estados foram mais bem descritos ou pelo modelo de Richards ou por sua versão generalizada. O modelo de Richards, em particular, foi capaz de identificar com razoável confiabilidade o surgimento do ponto de inflexão para os estados que só recentemente alcançaram esse estágio da epidemia, como foi o caso do Piauí, Rio Grande do Norte e Sergipe. Esse modelo também é capaz de prever quando a inflexão está prestes a acontecer, como é o caso da Bahia. O modelo generalizado de Richards, por sua vez, mostrou-se mais apropriado para descrever curvas epidêmicas de estados que estão em uma fase mais desenvolvida da epidemia, como Ceará e Pernambuco, quando as curvas epidêmicas já apresentam uma tendência mais consolidada de saturação em direção ao platô

Situação da Epidemia de Covid-19 no Brasil em Agosto de 2020: Maioria do Estados do Norte-Nordeste em Saturação e Estados do Sul em Aceleração ou Leve Desaceleração

In this Technical Note we analyze the cumulative curves of deaths attributed to Covid-19 in the 26 Brazilian states and the Federal District until August 21, 2020. Mathematical growth models implemented by the ModInterv Covid-19 application, which can be accessed via internet browser or via a mobile app available at the Google Play Store, were used to investigate at which stage the epidemic is in each of these entities of the Federation. The analysis revealed that almost all states in the Northern and Northeastern regions are in the saturation phase, when the epidemic is relatively under control, while in all Southern states and in most states in the Midwest the epidemic is still accelerating or shows only a slight deceleration. The Southeastern region presents a great diversity of epidemic stages, with each state at a different stage, ranging from acceleration to saturation.Nesta Nota Técnica nós analisamos as curvas acumuladas de mortes atribuídas à Covid-19 nos 26 estados e Distrito Federal até o dia 21 de agosto de 2020. Foram utilizados modelos matemáticos de crescimento implementados pelo aplicativo ModInterv Covid-19, que pode ser acessado via internet (http://fisica.ufpr.br/modinterv) ou através de aplicativo para celular disponível na Play Store (https://play.google.com/store/apps/details?id=com.tanxe.covid_19), para investigar em qual fase da epidemia cada um dessas unidades da federação se encontra. A análise revelou que quase todos os estados das Regiões Norte e Nordeste encontram-se em uma fase de saturação, quando a epidemia está relativamente sob controle, ao passo que em todos os estados do Sul e a maioria dos estados do Centro-Oeste a epidemia ainda está em aceleração ou apresenta apenas uma leve desaceleração. A Região Sudeste apresenta uma grande diversidade de estágios da epidemia, com cada estado em um estágio diferente, indo de acelerado à saturação

Recife e Belém são atualmente as únicas capitais que já estão na fase de saturação da Covid-19 no Brasil

In this technical note we analyze the accumulated fatality curves attributed to Covid-19 in the 27 Brazilian state capitals until July 19, 2020. We employed three mathematical growth models to assess at which stage of the epidemic each of these cities is at. These models were implemented in the Modinterv Covid-19 application, developed by the Federal Universities of Paraná, Pernambuco and Sergipe, which can be accessed through the <http://fisica.ufpr.br/modinterv> page. The analysis reveals that only Recife and Belém appear to have reached the saturation phase of the epidemic, when the accumulated fatality curve begins to approach the plateau. Among the other capitals, eight are still in the initial phase of rapid growth and seventeen are in the intermediate phase, when the epidemic curve has already passed through the inflection point but is still relatively far from the plateau.Nessa nota técnica analisamos as curvas acumuladas de mortes atribuídas à Covid-19 nas 27 capitais brasileiras até o dia 19 de julho de 2020. Empregamos três modelos matemáticos de crescimento para avaliar em que fase da epidemia encontra-se cada uma dessas cidades. Esses modelos  foram implementados  no aplicativo Modinterv Covid-19, desenvolvido pelas Universidades Federais do Paraná, Pernambuco e Sergipe, o qual pode ser acessado através da página http://fisica.ufpr.br/modinterv. A análise revela que apenas Recife e Belém aparentam ter atingido a fase de saturação da epidemia, quando a curva acumulada de morte começa a se aproximar do platô. Entre as demais capitais, oito ainda estão na fase inicial de crescimento rápido e dezessete estão na fase intermediária, quando a curva epidêmica já passou pelo ponto de inflexão mas ainda está relativamente distante do platô

Association of Phosphorylated Tau Biomarkers With Amyloid Positron Emission Tomography vs Tau Positron Emission Tomography

IMPORTANCE: The recent proliferation of phosphorylated tau (p-tau) biomarkers has raised questions about their preferential association with the hallmark pathologies of Alzheimer disease (AD): amyloid-β plaques and tau neurofibrillary tangles. OBJECTIVE: To determine whether cerebrospinal fluid (CSF) and plasma p-tau biomarkers preferentially reflect cerebral β-amyloidosis or neurofibrillary tangle aggregation measured with positron emission tomography (PET). DESIGN, SETTING, AND PARTICIPANTS: This was a cross-sectional study of 2 observational cohorts: the Translational Biomarkers in Aging and Dementia (TRIAD) study, with data collected between October 2017 and August 2021, and the Alzheimer's Disease Neuroimaging Initiative (ADNI), with data collected between September 2015 and November 2019. TRIAD was a single-center study, and ADNI was a multicenter study. Two independent subsamples were derived from TRIAD. The first TRIAD subsample comprised individuals assessed with CSF p-tau (p-tau181, p-tau217, p-tau231, p-tau235), [18F]AZD4694 amyloid PET, and [18F]MK6240 tau PET. The second TRIAD subsample included individuals assessed with plasma p-tau (p-tau181, p-tau217, p-tau231), [18F]AZD4694 amyloid PET, and [18F]MK6240 tau PET. An independent cohort from ADNI comprised individuals assessed with CSF p-tau181, [18F]florbetapir PET, and [18F]flortaucipir PET. Participants were included based on the availability of p-tau and PET biomarker assessments collected within 9 months of each other. Exclusion criteria were a history of head trauma or magnetic resonance imaging/PET safety contraindications. No participants who met eligibility criteria were excluded. EXPOSURES: Amyloid PET, tau PET, and CSF and plasma assessments of p-tau measured with single molecule array (Simoa) assay or enzyme-linked immunosorbent assay. MAIN OUTCOMES AND MEASURES: Associations between p-tau biomarkers with amyloid PET and tau PET. RESULTS: A total of 609 participants (mean [SD] age, 66.9 [13.6] years; 347 female [57%]; 262 male [43%]) were included in the study. For all 4 phosphorylation sites assessed in CSF, p-tau was significantly more closely associated with amyloid-PET values than tau-PET values (p-tau181 difference, 13%; 95% CI, 3%-22%; P = .006; p-tau217 difference, 11%; 95% CI, 3%-20%; P = .003; p-tau231 difference, 15%; 95% CI, 5%-22%; P < .001; p-tau235 difference, 9%; 95% CI, 1%-19%; P = .02) . These results were replicated with plasma p-tau181 (difference, 11%; 95% CI, 1%-22%; P = .02), p-tau217 (difference, 9%; 95% CI, 1%-19%; P = .02), p-tau231 (difference, 13%; 95% CI, 3%-24%; P = .009), and CSF p-tau181 (difference, 9%; 95% CI, 1%-21%; P = .02) in independent cohorts. CONCLUSIONS AND RELEVANCE: Results of this cross-sectional study of 2 observational cohorts suggest that the p-tau abnormality as an early event in AD pathogenesis was associated with amyloid-β accumulation and highlights the need for careful interpretation of p-tau biomarkers in the context of the amyloid/tau/neurodegeneration, or A/T/(N), framework

A reassessment of the historical fossil findings from Bahia State (Northeast Brazil) reveals a diversified dinosaur fauna in the Lower Cretaceous of South America

Supposed dinosaur remains were collected between 1859 and 1906 in the Lower Cretaceous Recôncavo Basin (Northeast Brazil). Since these materials remained undescribed, and most were considered lost. Recently, some of these historical specimens were rediscovered in the Natural History Museum of London, providing an opportunity to revisit them after 160 years. The specimens come from five different sites, corresponding to the Massacará (Berriasian-Barremian) and Ilhas (Valanginian-Barremian) groups. Identified bones comprise mainly isolated vertebral centra from ornithopods, sauropods, and theropods. Appendicular remains include a theropod pedal phalanx, humerus, and distal half of a left femur with elasmarian affinities. Despite their fragmentary nature, these specimens represent the earliest dinosaur bones discovered in South America, enhancing our understanding of the Cretaceous dinosaur faunas in Northeast Brazil. The dinosaur assemblage in the Recôncavo Basin resembles coeval units in Northeast Brazil, such as the Rio do Peixe Basin, where ornithopods coexist with sauropods and theropods. This study confirms the presence of ornithischian dinosaurs in Brazil based on osteological evidence, expanding their biogeographic and temporal range before the continental rifting between South America and Africa. Additionally, these findings reinforce the fossiliferous potential of Cretaceous deposits in Bahia State, which have been underexplored since their initial discoveries.</p