Canards, Folded Nodes, and Mixed-Mode Oscillations in Piecewise-Linear Slow-Fast Systems

Canard-induced phenomena have been extensively studied in the last three decades, from both the mathematical and the application viewpoints. Canards in slow-fast systems with (at least) two slow variables, especially near folded-node singularities, give an essential generating mechanism for mixed-mode oscillations (MMOs) in the framework of smooth multiple timescale systems. There is a wealth of literature on such slow-fast dynamical systems and many models displaying canard-induced MMOs, particularly in neuroscience. In parallel, since the late 1990s several papers have shown that the canard phenomenon can be faithfully reproduced with piecewise-linear (PWL) systems in two dimensions, although very few results are available in the three-dimensional case. The present paper aims to bridge this gap by analyzing canonical PWL systems that display folded singularities, primary and secondary canards, with a similar control of the maximal winding number as in the smooth case. We also show that the singular phase portraits are compatible in both frameworks. Finally, we show using an example how to construct a (linear) global return and obtain robust PWL MMOs

Liver haemangioma: common and uncommon findings and how to improve the differential diagnosis

Haemangiomas are common focal liver lesions, generally detected in the work-up of asymptomatic patients. From the pathological point of view, they can be classified as small (capillary) or large, with cavernous vascular spaces that may show thrombosis, calcifications and hyalinisation. The polymorphic imaging appearance of haemangiomas depends on their histological features and flow pattern. The widespread use of cross-sectional imaging has allowed an increased detection rate and a better characterisation of this benign tumour. Recent developments of ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) providing high spatial and temporal resolution, together with the use of new contrast agents and/or pulse sequences has broadened the spectrum of imaging findings, contributing to diagnostic refinement in difficult cases. The scope of the present article is to provide an overview of the range of appearances of haemangiomas, explored with recent cross-sectional imaging modalities, emphasising its atypical findings as explored by temporally resolved contrast-enhanced imaging

Hidronefrose na síndrome de Schinzel-Giedion: um achado importante para o diagnóstico

A síndrome de Schinzel-Giedion é uma patologia genética rara de etiologia desconhecida e herança autossômica recessiva. Caracteriza-se pela presença de um fácies grotesco, hipoplasia da porção média da face, hipertricose, múltiplas anomalias esqueléticas, malformações cardíacas e renais.As anomalias craniofaciais desta síndrome podem lembrar o fácies de uma doença metabólica de depósito. O objetivo deste relato foi enfatizar a importância da hidronefrose congênita bilateral no diagnóstico da síndrome de Schinzel-Giedion . Descrevemos o primeiro caso brasileiro de um recém-nascido com fácies típico, hipertricose generalizada, anomalias esqueléticas, cardíacas e hidronefrose bilateral, detectada pela ultrassonografia fetal e, posteriormente, confirmada pelo mesmo método. O estudo cromosômico foi normal. Na literatura, de 35 casos descritos, 31 apresentavam hidronefrose, o que constitui um achado fundamental para o diagnóstico da patologia. Dessa forma, acreditamos que se a síndrome de Schinzel-Giedion fosse indexada como uma das causas de hidronefrose congênita, seu diagnóstico seria facilitado, uma vez que a maioria dos outros achados desta síndrome, com exceção da hidronefrose, é inespecífica e comum a diversas outras síndromes genéticas.Schinzel-Giedion syndrome is a rare autosomal recessive disorder characterized by coarse facies, midface retraction, hypertrichosis, multiple skeletal anomalies, and cardiac and renal malformations. Craniofacial abnormalities of this syndrome sometimes resemble a storage or metabolic disease. The pathogenesis of the disease remains unknown. The objective of this report was to emphasize the importance of congenital bilateral hydronephrosis for the diagnosis of Schinzel-Giedion syndrome. We describe the first Brazilian case of a newborn with typical facies, generalized hypertrichosis, cardiac and skeletal anomalies, and bilateral hydronephrosis detected during pregnancy and confirmed later by abdominal ultrasonography. Chromosomal constitution was normal. Of the 35 cases already reported in the literature, 31 presented hydronephrosis, which is considered an important clue in diagnosis. If Schinzel-Giedion syndrome were indexed as a cause of congenital hydronephrosis, its identification would be greatly facilitated, since the majority of the other findings in Schinzel-Giedion syndrome are nonspecific and common to many genetic syndromes

The Influence of (Poly)phenol Intake in Saliva Proteome: Short- and Medium-Term Effects of Apple

The relationship between salivary proteome and dietary habits was studied in previous works, where a relationship between salivary proteins like cystatins and polyphenol/tannin levels in diet was observed. However, it remains to be elucidated if this association results from an effect of polyphenol-rich food ingestion on saliva composition. The aim of this work was to test the effects of apple intake on the saliva proteome, both in the short and medium term (after 4 days of continuous intake). By incubating saliva samples with apple phenolic-rich extract, protein bands containing -amylase, S-type cystatins, and proline-rich proteins (PRPs) appeared in the fraction that precipitated, showing the potential of these (poly)phenols to precipitate salivary proteins. Among these, it was salivary cystatins that presented changes in their levels both in the saliva samples collected immediately after apple intake and in the ones collected after 4 days of intake of an extra amount of apple. These results support the thought that intake is reflected in the salivary proteome. The effect of a polyphenol-rich food, like the apple, on salivary cystatin levels is in line with results observed in animal models and, due to the involvement of these proteins in oral food perception, it would be interesting to explore in future studies the effect of these changes on sensory perception and acceptance of polyphenol-rich food.</jats:p

Calcium Uptake and Proton Transport by Acidocalcisomes of Toxoplasma gondii

Acidocalcisomes are acidic calcium stores found in diverse organisms, being conserved from bacteria to humans. They possess an acidic matrix that contains several cations bound to phosphates, which are mainly present in the form of short and long polyphosphate chains. Their matrix is acidified through the action of proton pumps such as a vacuolar proton ATPase and a vacuolar proton pyrophosphatase. Calcium uptake occurs through a Ca2+/H+ countertransporting ATPase located in the membrane of the organelle. Acidocalcisomes have been identified in a variety of microorganisms, including Apicomplexan parasites such as Plasmodium and Eimeria species, and in Toxoplasma gondii. We report the purification and characterization of an acidocalcisome fraction from T. gondii tachyzoites after subcellular fractionation and further discontinuous iodixanol gradient purification. Proton and calcium transport activities in the fraction were characterized by fluorescence microscopy and spectrophotometric methods using acridine orange and arsenazo III, respectively. This work will facilitate the understanding of the function of acidocalcisomes in Apicomplexan parasites, as we can now isolate highly purified fractions that could be used for proteomic analysis to find proteins that may clarify the biogenesis of these organelles

Post-emergence selectivity of metribuzin to carrot.

The objective of this study was to evaluate the selectivity of the herbicide metribuzin to carrot plants as a function of genotype, dose, and plant growth stage at the time of application. Two experiments were carried out, one in a greenhouse and another in the field

Manufacturing process of a brain aneurysm biomodel in PDMS using rapid prototyping

Cerebral aneurysm is an abnormal dilatation of the blood vessel into a saccular form. They can originate in congenital defects, weakening of the arterial wall with increasing age, atherosclerotic changes, trauma and infectious emboli. The in vivo experiments are an effective way of investigating the appearance, validating new practices and techniques, but beyond ethical issues, these types of experiments are expensive and have low reproducibility. Thus, to better understand the pathophysiological and geometric aspects of an aneurysm, it is important to fabricate in vitro models capable of improving existing endovascular treatments, developing and validating theoretical and computational models. Another difficulty is in the preoperative period of the non-ruptured cerebral aneurysm, known for the success of the skilled acts because there is an anatomical structure of the aneurysm as its current position. Although there are technologies that facilitate three-dimensional video visualization in the case of aneurysms with complex geometries the operative planning is still complicated, so the development of the real three-dimensional physical model becomes advantageous. In this work, the entire process of manufacturing an aneurysm biomodel using polydimethylsiloxane (PDMS) is disassembled by rapid prototyping technology. The manufactured biomodels are able to perform different hemodynamic studies, validate theoretical data, numerical simulations and assist in the preoperative planning.info:eu-repo/semantics/publishedVersio