Matrix-Matching as an Improvement Strategy for the Detection of Pesticide Residues

More than 90% of the pesticides residues in apples are located in the peel. We developed a gas chromatography/ion trap tandem mass spectrometry method for investigating all detectable residues in the peel of 3 apple varieties. Sample preparation is based on the use of the Quick Easy Cheap Effective Rugged and Safe method on the whole fruit, the flesh, and the peel. Pesticide residues were quantified with solvent‐matched and matrix‐matched standards, by spiking apple sample extracts. Matrix effects dependent on the type of extract (fruit, flesh, or peel) and the apple variety were detected. The best data processing methods involved normalizing matrix effect rates by matrix‐matched internal/external calibration. Boscalid, captan, chlorpyrifos, fludioxonil, and pyraclostrobin were the most frequently detected pesticides. However, their concentrations in the whole fruit were below European maximum residue levels. Despite negative matrix effects, the residues in peel were detected at concentrations up to 10 times higher than those in whole fruits. Consequently, other pesticide residues present at concentrations below the limit of quantification in the whole fruit were detected in the peel

La sensibilité à, organisatrice de l'expérience vécue

Cette contribution trouve sa raison dans nos insatisfactions de formateurs confrontés à l'importante variabilité interindividuelle de la " présence active " des pratiquants et de leurs apprentissages : au volley-ball, certains progressent rapidement, d'autres quasiment pas. Les critères classiquement avancés (qualités physiques, volume de pratique antérieure, adresse spécifique, motivation à pratiquer) ne rendent pas compte de ces différentiels de " présence active " et d'apprentissage repérables dans les divers cadres de pratique (enseignement scolaire obligatoire et optionnel, secteur associatif). Cette insatisfaction éthique a généré une question de recherche visant une formation plus pertinente. Nos propos se limiteront au rapport qu'entretiennent en acte les joueurs avec le jeu et les situations du jeu. Le qualificatif de " pratiquants " souligne la restriction à ce seul aspect d'une activité assurément plus complexe. La préoccupation permanente de formation et l'évolution du travail de terrain nous ont fait éviter toute école doctrinale pour retenir une position hybride : une anthropologie cognitive non mentaliste empruntant à des philosophies de la vie formant à nos yeux un ensemble d'orientations composites mais compatibles ; une éthologie phénoménologique des pratiques humaines ordinaires, perspective descriptive et comparative des actes inspirée de Thinès (1980), s'intéressant aux relations signifiantes avec le monde naturel spécifique (Umwelt). L'ensemble du propos s'inscrit dans l'approche énactive, une phénoménologie qui s'efforce de saisir l'expérience humaine pour remédier à l'absence de sens commun dans la définition de la cognition (Varela, 1989). La distinction entre changement qualitatif global et changement quantitatif a pour nous le statut d'hypothèse interprétative des inégalités d'apprentissages dont nous constatons sur le terrain qu'elles se creusent généralement lors de la formation. Elle ne consiste pas en un choix a priori, mais ressort a posteriori de nos études, suite : - au repérage, après examen conjoint des matériaux, de trois modes différents de pratique viable nous semblant relever de trois sensibilités à ; - au constat que l'évolution ne répond ni à une logique de " stades " (au sens d'un passage nécessaire par l'un des états avant d'accéder à un autre), ni à une logique d'expertise ; - au repérage de changements importants, d'ordre global, du mode de pratique chez certains joueurs : l'ancienne régularité comportementale laisse place à une nouvelle régularité. La sensibilité est la cible de notre formation, le plus tôt possible, pour tous les pratiquants : notre travail ayant été généré/alimenté par des questions éthiques liées à une visée professionnelle, nous récusons la césure chercheur/formateur. Aussi assumons-nous d'être des manipulateurs suscitant des vécus compatibles avec les apprentissages spécifiques du volley-ball. Nous sommes conscients d'être normalisateurs, en ce que nous visons à réduire l'écart entre la sensibilité à initiale (la norme/valeur et les conceptualisations en acte sous-jacentes) des pratiquants et celle qui nous paraît favoriser ces acquisitions. Une modélisation des conduites peu à peu construite au sein de notre processus formation-recherche propose que l'activité et le vécu du pratiquant sont issus de la coordination de plusieurs registres. Non isolables, ces derniers constitueraient chacun un module perception-action établissant ses propres événements informationnels et assurant ses contributions motrices à l'activité d'ensemble. Une pluralité de vécus et d'activités caractériserait donc le tout complexe et organisé émergeant de ces registres interactifs

Species-specific responses to landscape fragmentation: implications for management strategies

Habitat fragmentation affects the integrity of many species, but little is known about species-specific sensitivity to fragmentation. Here, we compared the genetic structure of four freshwater fish species differing in their body size (Leuciscus cephalus; Leuciscus leuciscus; Gobio gobio and Phoxinus phoxinus) between a fragmented and a continuous landscape. We tested if, overall, fragmentation affected the genetic structure of these fish species, and if these species differed in their sensitivity to fragmentation. Fragmentation negatively affected the genetic structure of these species. Indeed, irrespective of the species identity, allelic richness and heterozygosity were lower, and population divergence was higher in the fragmented than in the continuous landscape. This response to fragmentation was highly species-specific, with the smallest fish species (P. phoxinus) being slightly affected by fragmentation. On the contrary, fish species of intermediate body size (L. leuciscus and G. gobio) were highly affected, whereas the largest fish species (L. cephalus) was intermediately affected by fragmentation. We discuss the relative role of dispersal ability and effective population size on the responses to fragmentation we report here. The weirs studied here are of considerable historical importance. We therefore conclude that restoration programmes will need to consider both this societal context and the biological characteristics of the species sharing this ecosyste

ParaCircE, a parallel Gaussian Random Field (GRF) generator

International audienc

Lessons Learned from 6 Years of a Remote Programming Challenge Activity with Automatic Supervision

peer reviewedIn an ``Introduction to Programming'' course dedicated to first-year students, many students tend to procrastinate and do not autonomously process step by step new topics taught over time. In response to that trend, a tool (called CAFÉ) was implemented to supervise a remote activity spread over the semester, by instantaneously correcting students' exercises and providing feedback to guide them in refining their solutions. This paper presents and discusses the current impact of the system on students’ learning, based on six years of activity. The results validate the high potential of such a tool, but also highlight many students do not take advantage of that opportunity to boost their learning. That opens doors to some significant upgrades in the tool, mainly consisting in offering a closer guidance to students through a larger range of regular activities. While CAFÉ was initially standing as an isolated tool offering correction and feedbacks, this paper advocates for CAFÉ becoming an integral part of the course, leading to a consistent synergy between in-person and continuous remote learning

Uses of 360° video in referees' reflectivity training: Possibilities and limitations

IntroductionA pedagogical innovation backed by an online device using 360° video had been devised to train young team sports referees (handball, soccer, rugby) to be more reflective. The objective of this exploratory research was to investigate the ways young student referees use 360° videos in allo-confrontation when carrying out some exercises involving open questions about their viewing experience.MethodsStudent referees' answers were recorded. A grounded analysis of these answers enabled us not only to identify their main focuses when viewing the 360° videos but also to distinguish different cognitive stances.ResultsThe grounded analysis revealed (1) idiographic differences between student referees in the video sequencing, although the participants seemed to share the same reference points, (2) two kinds of focus, one on the unfolding of the game and another one on the referee peer's activity, and (3) different perspectives according to which student referees use video and to initiate a reflection on a differentiation of several types of immersion: empathetic, simulation, exploratory.DiscussionThis study highlighted the conditions under which referees' reflectivity was fostered by the use of 360° video during allo-confrontation. Some perspectives for the evolution of 360° video supports for designing training courses for referees are proposed

Evaluation and prevention of the negative matrix effect of terpenoids on pesticides in apples quantification by gas chromatography–tandem mass spectrometry

The sample matrix can enhance the gas chromatography signal of pesticide residues relative to that obtained with the same concentration of pesticide in solvent. This paper is related to negative matrix effects observed in coupled gas chromatography-mass spectrometry ion trap (GC/MS2) quantification of pesticides in concentrated extracts of apple peel prepared by the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) method. It is focused on the pesticides most frequently used on the apple varieties studied, throughout the crop cycle, right up to harvest, to combat pests and diseases and to improve fruit storage properties. Extracts from the fleshy receptacle (flesh), the epiderm (peel) and fruit of three apple varieties were studied by high-performance thin-layer chromatography hyphenated with UV–vis light detection (HPTLC/UV visible). The peel extracts had high concentrations of triterpenic acids (oleanolic and ursolic acids), reaching 25mgkg−1, whereas these compounds were not detected in the flesh extracts (<0.05mgkg−1). A significant relationship has been found between the levels of these molecules and negative matrix effects in GC/MS2. The differences in the behavior of pesticides with respect to matrix effects can be accounted for by the physicochemical characteristics of the molecules (lone pairs, labile hydrogen, conjugation). The HPTLC/UV visible method developed here for the characterization of QuEChERS extracts acts as a complementary clean-up method, aimed to decrease the negative matrix effects of such extracts

Pratiques pédagogiques inclusives en enseignement postsecondaire, en contexte pandémique

En enseignement postsecondaire, la mise en œuvre de pratiques pédagogiques inclusives dépend à ce jour d’initiatives individuelles des enseignants. La pandémie de COVID-19 a toutefois forcé la mise en ligne des cours, amenant les enseignants à revoir leurs pratiques. L’objectif de cette étude consiste à analyser l’évolution des usages de pratiques pédagogiques inclusives au postsecondaire, plus précisément en enseignement collégial, à la suite de la transition des cours en présentiel vers des cours hybrides et en ligne pendant la pandémie. Suivant une méthodologie mixte de recherche, des données quantitatives et qualitatives ont été recueillies auprès d’étudiants de 10 établissements à travers le Québec, par le biais de questionnaires avant et pendant la pandémie (n = 1242) complétés par des entrevues auprès d’étudiants en situation de handicap (n = 25). Les résultats montrent une augmentation de l’accessibilité du matériel pédagogique, une progression sur l’utilisation d’outils technologiques pour diversifier les formats de présentation des contenus et pour faciliter la communication et la participation, ainsi qu’une certaine diversification des activités d’évaluation et une plus grande flexibilité dans les dates de remise. Toutefois, une régression des pratiques est constatée quant à la variété des méthodes pédagogiques et aux occasions d’engagement des étudiants dans les cours hybrides et en ligne. L’enseignement a aussi été perçu comme moins inclusif et moins structuré par les étudiants, sauf dans les cours où les enseignants réservaient un temps spécifique pour les questions et pour résumer les points importants. Les résultats sont discutés à la lumière des principes et des pratiques visant à soutenir les apprentissages et l’engagement de tous les étudiants, en reconnaissance de la variabilité de leurs besoins et préférences.In postsecondary education, the implementation of inclusive teaching strategies has so far relied on individual faculty initiatives. However, the COVID-19 pandemic forced faculty to transition to online courses, causing teachers to rethink their teaching practices. The purpose of this study is to analyze the evolution of inclusive teaching strategies in postsecondary education, specifically in college education, following the transition from face-to-face to blended and online courses during the pandemic. Using a mixed-methods research design, quantitative and qualitative data were collected from students at 10 institutions across Quebec through questionnaires before and during the pandemic (n = 1242) supplemented by interviews with students with disabilities (n = 25). The results show an increase in the accessibility of course materials, a progression in the use of technological tools for content presentation and to facilitate communication and participation, as well as some diversification of assessment activities and greater flexibility in the deadlines. However, there was a regression in teaching practices with respect to the variety of pedagogical methods and opportunities for student engagement in blended and online courses. Lectures were also perceived as less inclusive and less structured by students, except in courses where instructors had planned specific times for students’ questions and to summarize important points. The results are discussed considering principles and practices to support learning and engagement for all students, recognizing the variability of their needs and preferences

Genetic admixture between captive-bred and wild individuals affects patterns of dispersal in a brown trout (Salmo trutta) population

Genetic admixture between captive-bred and wild individuals has been demonstrated to affect many individual traits, although little is known about its potential influence on dispersal, an important trait governing the eco-evolutionary dynamics of populations. Here, we quantified and described the spatial distribution of genetic admixture in a brown trout (Salmo trutta) population from a small watershed that was stocked until 1999, and then tested whether or not individual dispersal parameters were related to admixture between wild and captive-bred fish. We genotyped 715 fish at 17 microsatellite loci sampled from both the mainstream and all populated tributaries, as well as 48 fish from the hatchery used to stock the study area. First, we used Bayesian clustering to infer local genetic structure and to quantify genetic admixture. We inferred first generation migrants to identify dispersal events and test which features (genetic admixture, sex and body length) affected dispersal parameters (i.e. probability to disperse, distance of dispersal and direction of the dispersal event). We identified two genetic clusters in the river basin, corresponding to wild fish on the one hand and to fish derived from the captive strain on the other hand, allowing us to define an individual gradient of admixture. Individuals with a strong assignment to the captive strain occurred almost exclusively in some tributaries, and were more likely to disperse towards a tributary than towards a site of the mainstream. Furthermore, dispersal probability increased as the probability of assignment to the captive strain increased, and individuals with an intermediate level of admixture exhibited the lowest dispersal distances. These findings show that various dispersal parameters may be biased by admixture with captive-bred genotypes, and that management policies should take into account the differential spread of captive-bred individuals in wild populations