Nonlinear oscillatory mixing in the generalized Landau scenario

We present a set of phase-space portraits illustrating the extraordinary oscillatory possibilities of the dynamical systems through the so-called generalized Landau scenario. In its simplest form the scenario develops in N dimensions around a saddle-node pair of fixed points experiencing successive Hopf bifurcations up to exhausting their stable manifolds and generating N-1 different limit cycles. The oscillation modes associated with these cycles extend over a wide phase-space region by mixing ones within the others and by affecting both the transient trajectories and the periodic orbits themselves. A mathematical theory covering the mode-mixing mechanisms is lacking, and our aim is to provide an overview of their main qualitative features in order to stimulate research on it.Peer ReviewedPostprint (author's final draft

Nonlinear complexification of periodic orbits in the generalized Landau scenario

We have found a way for penetrating the space of the dynamical systems towards systems of arbitrary dimension exhibiting the nonlinear mixing of a large number of oscillation modes through which extraordinarily complex time evolutions may arise. The system design is based on assuring the occurrence of a number of Hopf bifurcations in a set of fixed points of a relatively generic system of ordinary differential equations, in which the main peculiarity is that the nonlinearities appear through functions of a linear combination of the system variables. The paper outlines the design procedure and presents a selection of numerical simulations with a variety of designed systems whose dynamical behaviors are really rich and full of unknown features. For concreteness, the presentation is focused to illustrating the oscillatory mixing effects on the periodic orbits, through which the harmonic oscillation born in a Hopf bifurcation becomes successively enriched with the intermittent incorporation of other oscillation modes of higher frequencies while the orbit remains periodic and without necessity of bifurcating instabilities. Even in the absence of a proper mathematical theory covering the nonlinear mixing mechanisms we find enough evidence to expect that the oscillatory scenario be truly scalable concerning the phase space dimension, the multiplicity of involved fixed points and the range of time scales, so that extremely complex but ordered dynamical behaviors could be sustained through it.Peer ReviewedPostprint (author's final draft

Nutritional quality of Vidal grass (Bothriochloa saccharoides) under dry tropical conditions

P?ginas 51-55Recurso Electr?nicoEste articulo contiene informaci?n acerca del pasto Vidal (Botriochloa saccharoides), gram?nea poco estudiada y que posee grandes cualidades a nivel nutricional y productivo tanto en monocultivo como en asociaci?n con especies arb?reas. Durante el desarrollo de esta investigaci?n se evaluaron las caracter?sticas de calidad nutricional del pasto Vidal durante sus diferentes etapas fenol?gicas (germinaci?n, vegetativa, reproductiva y senescencia). Para ello se estableci? una parcela en la granja ?CURDN? (Centro Universitario Regional del Norte del Tolima) ubicada en el municipio de Armero Guayabal. El ensayo fue desarrollado con el objetivo de determinar las caracter?sticas nutricionales m?s relevantes durante el desarrollo del ciclo del pasto Vidal. Seg?n los resultados obtenidos el pasto Botriochloa saccharoides present? un ciclo fenol?gico de 137 d?as, tiempo en el cual se observaron las fases de germinaci?n, prefloraci?n, floraci?n y senescencia a los 37, 91, 114 y 128 d?as respectivamente. El tiempo ideal para el primer pastoreo es aproximadamente a los 91 d?as etapa en la cual el pasto est? en estado de prefloraci?n con una PC de 5,24%; DIVMS 54,21%; 45,8% de FDA y 8,3% de lignina.ABSTRACT. This article contains information about Vidal grass (Botriochloa saccharoides) , which has been little studied although it has good nutritional and productive qualities as much in single-crop farming as in association with arboreal species. Throughout this project, the Characteristics of nutritional quality of Vidal grass were evaluated during their different stages of development (germination, vegetative, reproductive and senescence,). Then, an experimental plot was sown in the ?CURDN? farm (Centro Universitario Regional del Norte del Tolima), located in the municipality of Armero - Guayabal. According to the results obtained, the Botriochloa saccharoides grass presented a cycle of 137 days. The germination, vegetative, reproductive and senescence phases could be observed at the 37th , 91st , 114th and 128th days, respectively. The ideal time for the first harvest is immediately after the first stage is over (91 days), stage in which the grass has a CP of 5,24%; DMIVD 54,21%; 72,1% of ADF and 8,3% lignin

FGF23-klotho axis as predictive factors of fractures in type 2 diabetics with early chronic kidney disease

Background: The aim of our study was to evaluate the relevance of FGF23-klotho axis in the predisposition for bone fractures in type 2 diabetic patients with early chronic kidney disease. Methods: In a prospective study we included 126 type 2 diabetic patients with CKD stages 2-3 (from 2010 to 2017). We used descriptive statistics, ANOVA and chi-square test. Our population was divided into two groups according to the occurrence of a bone fracture event or not, and the groups were compared considering several biological and laboratorial parameters. We employed a multiple regression model to identify risk factors for bone fracture events and hazard ratios (HR) were calculated using a backward stepwise likelihood ratio (LR) Cox regression. Results: Patients with a fracture event displayed higher levels of FGF-23, Phosphorus, PTH, TNF-alpha, OxLDL, HOMA-IR, calcium x phosphorus product and ACR and lower levels of Osteocalcin, alpha-Klotho, 25(OH)D3 and eGFR compared with patients without a fracture event (p < 0.001). The number of patients with a fracture event was higher than expected within inclining CKD stages (chi 2, p = 0.06). The occurrence of fracture and the levels of TNF-alpha, klotho, 25(OH)D3 and OxLDL were found to predict patient entry into RRT (p < 0.05). Age, osteocalcin, alpha-Klotho and FGF-23 independently influenced the occurrence of bone fracture (p < 0.05). Conclusions: alpha-Klotho and FGF-23 levels may have a good clinical use as biomarkers to predict the occurrence of fracture events. (C) 2019 Elsevier Inc. All rights reserved.info:eu-repo/semantics/publishedVersio

The role of regular asymptomatic testing in reducing the impact of a COVID-19 wave

Testing for infection with SARS-CoV-2 is an important intervention in reducing onwards transmission of COVID-19, particularly when combined with the isolation and contact-tracing of positive cases. Many countries with the capacity to do so have made use of lab-processed Polymerase Chain Reaction (PCR) testing targeted at individuals with symptoms and the contacts of confirmed cases. Alternatively, Lateral Flow Tests (LFTs) are able to deliver a result quickly, without lab-processing and at a relatively low cost. Their adoption can support regular mass asymptomatic testing, allowing earlier detection of infection and isolation of infectious individuals. In this paper we extend and apply the agent-based epidemic modelling framework Covasim to explore the impact of regular asymptomatic testing on the peak and total number of infections in an emerging COVID-19 wave. We explore testing with LFTs at different frequency levels within a population with high levels of immunity and with background symptomatic PCR testing, case isolation and contact tracing for testing. The effectiveness of regular asymptomatic testing was compared with ‘lockdown’ interventions seeking to reduce the number of non-household contacts across the whole population through measures such as mandating working from home and restrictions on gatherings. Since regular asymptomatic testing requires only those with a positive result to reduce contact, while lockdown measures require the whole population to reduce contact, any policy decision that seeks to trade off harms from infection against other harms will not automatically favour one over the other. Our results demonstrate that, where such a trade off is being made, at moderate rates of early exponential growth regular asymptomatic testing has the potential to achieve significant infection control without the wider harms associated with additional lockdown measures

Educação no/do campo: caminhos para uma formação humana e uma visibilidade social

A Educação do Campo foi historicamente pensada a partir da relação entre educação e trabalho, ou seja, o trabalho (ontológico) do homem do campo vinha como condição primeira para a construção de uma formação humana que tenha como objetivo dar uma visibilidade social ao sujeito. A primeira parte do presente estudo foi realizado na década de 1990, no momento em que o contexto nacional era provocativo e sem ações significativas que apontassem ações para minimizar as mazelas que assolavam a educação Rural Brasileira, atualmente refletida conceitualmente e em práticas pontuais em educação no/do campo. Pretende-se aqui fazer um paralelo entre a década passada com os dias atuais, sem perder de vista atores e espaços. Utilizou-se como fundamentação o teórico Miguel Arroyo acrescido com estudos de Molina &amp; Caldart. O abordado trata da representação da escola para o aluno trabalhador rural. A pesquisa foi feita na comunidade de Ceraíma, distrito de Guanambi-BA, com 30 alunos do Ensino Fundamental, utilizando a investigação etnometodológica e estudos bibliográficos a fim de problematizar as temáticas pesquisadas. Naquele momento a escola significava mobilidade em torno de subempregos no mundo urbano e visibilidade social. Aproximando-se duas décadas os resultados permanecem e apontam outras mazelas produzidas nos centros urbanos e importado para o espaço rural.&nbsp

Hepatic abscess secondary to an unusual foreign body

Introduction: Liver abscess is a frequent cause of intra-abdominal infection, characterized by an encapsulated suppurative collection within the liver parenchyma, generally caused by pyogenic or amoebic agents. Those caused by foreign bodies are rare. Objective: To describe the clinical-surgical findings of a patient with liver abscess secondary to an unusual foreign body. Case: A 38-year-old male patient, inmate, who attended the general surgery clinic of the guardhouse, presenting with abdominal pain and fever. He refers that approximately 6 months ago he had ingested 3 foreign bodies. Conclusions: The ingestion of punctiform foreign bodies can trigger liver abscess, manifested with clinical characteristics typical of this disease, hence the importance of investigating the history to define the behavior, since in this case it differs from the rest; It's always surgical

Lactobacillus acidophilus Contributes to a Healthy Environment for Vaginal Epithelial Cells

Lactobacillus species in the female genital tract are thought to act as a barrier to infection. Several studies have demonstrated that lactobacilli can adhere to vaginal epithelial cells. However, little is known about how the adherence of lactobacilli to vaginal epithelial cells affects the acidity, cell viability, or proliferation of the lactobacilli themselves or those of vaginal epithelial cells. Lactobacillus acidophilus was co-cultured with immortalized human vaginal epithelial cells (MS74 cell line), and the growth of L. acidophilus and the acidity of the culture medium were measured. MS74 cell density and viability were also assessed by counting cell numbers and observing the cell attachment state. L. acidophilus showed exponential growth for the first 6 hr until 9 hr, and the pH was maintained close to 4.0-5.0 at 24 hr after culture, consistent with previous studies. The growth curve of L. acidophilus or the pH values were relatively unaffected by co-culture with MS74 cells, confirming that L. acidophilus maintains a low pH in the presence of MS74 cells. This co-culture model could therefore potentially be used to mimic vaginal conditions for future in vitro studies. On the other hand, MS74 cells co-cultured with L. acidophilus more firmly attached to the culture plate, and a higher number of cells were present compared to cells cultured in the absence of L. acidophilus. These results indicate that L. acidophilus increases MS74 cell proliferation and viability, suggesting that lactobacilli may contribute to the healthy environment for vaginal epithelial cells

A novel mutation in the OAR domain of the ARX gene

Mutations in ARX gene should be considered in patients with mental disabilityor/and epilepsy. It is an X-linked gene that has pleiotropic effects. Here, wereport the case of a boy diagnosed with Ohtahara syndrome. We performed themolecular analysis of the gene and identified a new missense mutation

Loss of AMP-activated protein kinase alpha 2 subunit in mouse beta-cells impairs glucose-stimulated insulin secretion and inhibits their sensitivity to hypoglycaemia

AMPK (AMP-activated protein kinase) signalling plays a key role in whole-body energy homoeostasis, although its precise role in pancreatic β-cell function remains unclear. In the present stusy, we therefore investigated whether AMPK plays a critical function in β-cell glucose sensing and is required for the maintenance of normal glucose homoeostasis. Mice lacking AMPKα2 in β-cells and a population of hypothalamic neurons (RIPCreα2KO mice) and RIPCreα2KO mice lacking AMPKα1 (α1KORIPCreα2KO) globally were assessed for whole-body glucose homoeostasis and insulin secretion. Isolated pancreatic islets from these mice were assessed for glucose-stimulated insulin secretion and gene expression changes. Cultured β-cells were examined electrophysiologically for their electrical responsiveness to hypoglycaemia. RIPCreα2KO mice exhibited glucose intolerance and impaired GSIS (glucose-stimulated insulin secretion) and this was exacerbated in α1KORIPCreα2KO mice. Reduced glucose concentrations failed to completely suppress insulin secretion in islets from RIPCreα2KO and α1KORIPCreα2KO mice, and conversely GSIS was impaired. β-Cells lacking AMPKα2 or expressing a kinase-dead AMPKα2 failed to hyperpolarize in response to low glucose, although KATP (ATP-sensitive potassium) channel function was intact. We could detect no alteration of GLUT2 (glucose transporter 2), glucose uptake or glucokinase that could explain this glucose insensitivity. UCP2 (uncoupling protein 2) expression was reduced in RIPCreα2KO islets and the UCP2 inhibitor genipin suppressed low-glucose-mediated wild-type mouse β-cell hyperpolarization, mimicking the effect of AMPKα2 loss. These results show that AMPKα2 activity is necessary to maintain normal pancreatic β-cell glucose sensing, possibly by maintaining high β-cell levels of UCP2