Canard Cycles and Poincar\'e Index of Non-Smooth Vector Fields on the Plane

This paper is concerned with closed orbits of non-smooth vector fields on the plane. For a subclass of non-smooth vector fields we provide necessary and sufficient conditions for the existence of canard kind solutions. By means of a regularization we prove that the canard cycles are singular orbits of singular perturbation problems which are limit periodic sets of a sequence of limit cycles. Moreover, we generalize the Poincar\'e Index for non-smooth vector fields.Comment: 20 pages, 25 figure

O1-5 Digital tools for physical activity assessment and brief counselling in Primary Health Care: The Portuguese model

Issue/problem Implementation of national systems for patients' physical activity (PA) assessment and counselling is a cost-effective strategy recommended in the WHO Global Action Plan for PA 2018-2030. Although Primary Health Care (PHC) professionals are recognized as key agents for PA promotion, challenges remain on how to develop feasible and scalable tools to support them in promoting patients' PA. The Portuguese model could help other countries improve PA assessment and brief counselling in PHC settings. This study aims to describe the tools' development and usage. Description of the problem The Portuguese Directorate-General of Health developed two evidence-based digital tools to support PA promotion by healthcare professionals: a) PA brief assessment tool; and b) brief counselling tool. The assessment tool was incorporated within the electronic medical health record software ?SClínico? in September 2017. It includes three questions: 1) how many days per week the patient performs any kind of PA (work, commuting or leisure-time); 2) how much time per day; and 3) how many hours per day the patient spends in sedentary behaviours. The PA brief counselling tool is available through the electronic medical prescription software ?PEM? since December 2017 and consists of five inter-related self-explanatory guides that can be delivered to patients (printed or by email), according to their motivation and PA levels. They facilitate person-centered and autonomy-supportive PA counselling, targeting specific behaviour change mediators, and using validated techniques. Results From September 2017 to December 2021, 159,179 patients had their PA assessed (2235 per 100,000 users of the National Health Service) and, from these, 16133 received PA brief counselling guides (177 per 100000 residents in Portugal, ≥ 15 years old), with a six-fold and three-fold increases, respectively, between 2018 and 2019 (previous to the COVID-19 pandemic). Future actions will address cost-effectiveness of this policy. Lessons The brief assessment and brief counselling tools were well-accepted and are increasingly being used, with potential for generalized adoption within the Portuguese Health Care System. Main messages Portugal has taken a decisive action to promote PA using PHC as a priority setting. PA tools usage is increasing considerably, highlighting the importance of making available easy-to-use PA promotion tools

Fluorometric Liposome Screen for Inhibitors of a Physiologically Important Bacterial Ion Channel

The bacterial K+ homeostasis machinery is widely conserved across bacterial species, and different from that in animals. Dysfunction in components of the machinery has an impact on intracellular turgor, membrane potential, adaptation to changes in both extracellular pH and osmolarity, and in virulence. Using a fluorescence-based liposome flux assay, we have performed a high-throughput screen to identify novel inhibitors of the KtrAB ion channel complex from Bacillus subtilis, a component of the K+ homeostasis machinery that is also present in many bacterial pathogens. The screen identified 41 compounds that inhibited K+ flux and that clustered into eight chemical groups. Many of the identified inhibitors were found to target KtrAB with an in vitro potency in the low µM range. We investigated the mechanisms of inhibition and found that most molecules affected either the membrane component of the channel, KtrB alone or the full KtrAB complex without a preference for the functional conformation of the channel, thus broadening their inhibitory action. A urea derivative molecule that inhibited the membrane component of KtrAB affected cell viability in conditions in which KtrAB activity is essential. With this proof-of-concept study, we demonstrate that targeting components of the K+ homeostasis machinery has the potential as a new antibacterial strategy and that the fluorescence-based flux assay is a robust tool for screening chemical libraries.This work was supported by FEDER funds through COMPETE 2020-POCI, Portugal 2020, and FCT – Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior: POCI-01-0145-FEDER-029863 (PTDC/BIA-BQM/29863/2017), and by “Fundação Luso-Americana para o Desenvolvimento” FLAD Life Science 2020 awarded to JM-C. We acknowledge FCT fellowship SFRH/BPD/105672/2015 and contract DL 57/2016/CP1355/CT0026 awarded to AF, fellowship SFRH/BPD/107785/2015 to AP, and fellowship SFRH/BD/123761/2016 to CT-D

Screening of yeasts capable of producing cellulase-free xylanase

Xylanases have largely been obtained from filamentous fungi and bacteria; few studies have investigated the production of this enzyme by yeasts. The aim of this study was to isolate yeasts from different sources, such as vegetables, cereal grains, fruits, and agro-industrial waste and to obtain yeasts capable of producing celulase-free xylanase. Samples were enriched using yeast malt broth, and yeasts were isolated on Wallerstein nutrient agar. In all, 119 yeast strains were isolated and evaluated in terms of their ability to degrade xylan, which was found in the medium by using agar degradation halos, the basis of this polysaccharide, and Congo red dye. Selected microorganisms were grown in complex medium and the enzymatic activities of endo-xylanase, β-xylosidase, carboxymetilcellulase, and filter paper cellulose were determined over 96 h of cultivation; the pH and biomass concentration were also evaluated. The yeast strain 18Y, which was isolated from chicory and later identified as Cryptococcus laurentii, showed the highest endo-xylanase activity (2.7 U.mL-1). This strain had the ability to produce xylanase with low levels of cellulase production (both CMCase [0.11 U.mL-1] and FPase [0.10 U.mL-1]). This result gives this strain great biotechnological potential since this enzyme can be used for industrial pulp and paper bleaching.Key words: Cryptococcus laurentii, endo-xylanase, xylan

Fatty acids profile of pulp and nuts of brazilian fruits

Fruits and nuts from the North and Northeast regions of Brazil were collected to determine the fatty acid profile of their oils. The species studied were Brazil (Bertholletia excelsa H. B. K.), Mucaja (Couma rigida M.), Inaja (Maximiliana maripa D.), Jenipapo (Genipa Americana L.), and Buriti (Mauritia flexuosa L.) nuts. Fatty acid methyl esters were analyzed by gas chromatography with flame ionization detection (GC-FID). Brazil nut major fatty acid was 18:3n-3 (alpha-linolenic acid), and Buriti nut had approximately 23 times more 18: 3n-3 than the pulp. Mucaja nut presented high content of 12: 0 (lauric acid) and 16: 0 (palmitic acid), and Mucaja pulp showed significant levels of 18: 2n-6 (linoleic acid). Considering the PUFA (polyunsaturated fatty acid) sum values, almost all fruits and nuts analyzed presented very high levels of these compounds. Regarding n-6/n-3 ratio, only Brazil Nut, Buriti Nut, Inaja pulp, and Jenipapo pulp corresponded to the desired profile. These Brazilian fruits and nuts could be of potential interest due to their high nutritive value and lipid content.31495095

Assessing the Health of Richibucto Estuary with the Latent Health Factor Index

The ability to quantitatively assess the health of an ecosystem is often of great interest to those tasked with monitoring and conserving ecosystems. For decades, research in this area has relied upon multimetric indices of various forms. Although indices may be numbers, many are constructed based on procedures that are highly qualitative in nature, thus limiting the quantitative rigour of the practical interpretations made from these indices. The statistical modelling approach to construct the latent health factor index (LHFI) was recently developed to express ecological data, collected to construct conventional multimetric health indices, in a rigorous quantitative model that integrates qualitative features of ecosystem health and preconceived ecological relationships among such features. This hierarchical modelling approach allows (a) statistical inference of health for observed sites and (b) prediction of health for unobserved sites, all accompanied by formal uncertainty statements. Thus far, the LHFI approach has been demonstrated and validated on freshwater ecosystems. The goal of this paper is to adapt this approach to modelling estuarine ecosystem health, particularly that of the previously unassessed system in Richibucto in New Brunswick, Canada. Field data correspond to biotic health metrics that constitute the AZTI marine biotic index (AMBI) and abiotic predictors preconceived to influence biota. We also briefly discuss related LHFI research involving additional metrics that form the infaunal trophic index (ITI). Our paper is the first to construct a scientifically sensible model to rigorously identify the collective explanatory capacity of salinity, distance downstream, channel depth, and silt-clay content --- all regarded a priori as qualitatively important abiotic drivers --- towards site health in the Richibucto ecosystem.Comment: On 2013-05-01, a revised version of this article was accepted for publication in PLoS One. See Journal reference and DOI belo

Multi-omics phenotyping of the gut-liver axis reveals metabolic perturbations from a low-dose pesticide mixture in rats.

Health effects of pesticides are not always accurately detected using the current battery of regulatory toxicity tests. We compared standard histopathology and serum biochemistry measures and multi-omics analyses in a subchronic toxicity test of a mixture of six pesticides frequently detected in foodstuffs (azoxystrobin, boscalid, chlorpyrifos, glyphosate, imidacloprid and thiabendazole) in Sprague-Dawley rats. Analysis of water and feed consumption, body weight, histopathology and serum biochemistry showed little effect. Contrastingly, serum and caecum metabolomics revealed that nicotinamide and tryptophan metabolism were affected, which suggested activation of an oxidative stress response. This was not reflected by gut microbial community composition changes evaluated by shotgun metagenomics. Transcriptomics of the liver showed that 257 genes had their expression changed. Gene functions affected included the regulation of response to steroid hormones and the activation of stress response pathways. Genome-wide DNA methylation analysis of the same liver samples showed that 4,255 CpG sites were differentially methylated. Overall, we demonstrated that in-depth molecular profiling in laboratory animals exposed to low concentrations of pesticides allows the detection of metabolic perturbations that would remain undetected by standard regulatory biochemical measures and which could thus improve the predictability of health risks from exposure to chemical pollutants

Staphylococcus epidermidis glucose uptake in biofilm versus planktonic cells

The aim of this work was to compare the glucose uptake of biofilms formed by four different Staphylococcus epidermidis strains as well as to compare between sessile and planktonic cells of the same strain. Biofilm cells showed a lower level of glucose uptake compared to planktonic cells. Moreover, glucose uptake by cells in the sessile form was strongly influenced by biofilm composition. Therefore, this work helps to confirm the phenotypic variability of S. epidermidis strains and the different behaviour patterns between sessile and free cells.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/ESP/42688/2001; SFRH/BD/19265/2004