Spatial competition with unit-demand functions

This paper studies a spatial competition game between two firms that sell a homogeneous good at some pre-determined fixed price. A population of consumers is spread out over the real line, and the two firms simultaneously choose location in this same space. When buying from one of the firms, consumers incur the fixed price plus some transportation costs, which are increasing with their distance to the firm. Under the assumption that each consumer is ready to buy one unit of the good whatever the locations of the firms, firms converge to the median location: there is minimal differentiation. In this article, we relax this assumption and assume that there is an upper limit to the distance a consumer is ready to cover to buy the good. We show that the game always has at least one Nash equilibrium in pure strategy. Under this more general assumption, the "minimal differentiation" principle no longer holds in general. At equilibrium, firms choose "minimal", "intermediate" or "full" differentiation, depending on this critical distance a consumer is ready to cover and on the shape of the distribution of consumers' locations

La zoomification de l’enseignement médical : les solutions virtuelles précipitées lors de la COVID-19 peuvent-elles nous préparer pour une prochaine perturbation dans l’enseignement? Revue exploratoire

Introduction: In response to the COVID-19 pandemic, educators have increasingly shifted delivery of medical education to online/distance learning. Given the rapid and heterogeneous nature of adaptations; it is unclear what interventions have been developed, which strategies and technologies have been leveraged, or, more importantly, the rationales given for designs. Capturing the content and skills that were shifted to online, the type of platforms used for the adaptations, as well as the pedagogies, theories, or conceptual frameworks used to inform the adapted educational deliveries can bolster continued improvement and sustainability of distance/online education while preparing medical education for future large-scale disruptions. Methods: We conducted a scoping review to map the rapid medical educational interventions that have been adapted or transitioned to online between December 2019 and August 2020. We searched MEDLINE, EMBASE, Education Source, CINAHL, and Web of Science for articles pertaining to COVID-19, online (distance) learning, and education for medical students, residents, and staff. We included primary research articles and reports describing adaptations of previous educational content to online learning. Results: From an initial 980 articles, we identified 208 studies for full-text screening and 100 articles for data extraction. The majority of the reported scholarship came from Western Countries and was published in clinical science journals. Cognitive content was the main type of content adapted (over psychomotor, or affective). More than half of the articles used a video-conferencing software as the platform to pivot their educational intervention into virtual. Unfortunately, most of the reported work did not disclose their rationale for choosing a platform. Of those that did, the majority chose technological solutions based on availability within their institutions. Similarly, most of the articles did not report the use of any pedagogy, theory, or framework to inform the educational adaptations.Introduction : En réponse à la pandémie de la COVID-19, l’enseignement médical a été progressivement déplacé vers l’espace virtuel. Compte tenu de la rapidité et de l’hétérogénéité des adaptations opérées, nous n’avons qu’une idée peu précise des activités éducatives élaborées, des stratégies et des technologies mobilisées et, plus important encore, des raisons avancées pour les motiver. Une meilleure connaissance du contenu et des compétences dont l’enseignement a été transféré en ligne, du type de plateformes utilisées pour le virage, ainsi que des pédagogies, des théories ou des cadres conceptuels utilisés pour guider les activités éducatives adaptées soutiendrait une amélioration continue et la pérennité de l’enseignement à distance, tout en préparant la formation médicale à de futures perturbations d’envergure. Méthodes : Nous avons effectué une revue exploratoire pour recenser les activités éducatives en médecine qui ont été expéditivement adaptées ou transposées en ligne entre décembre 2019 et août 2020. Nous avons interrogé les bases de données MEDLINE, EMBASE, Education Source, CINAHL et Web of Science à la recherche d’articles portant sur la COVID-19, sur l’apprentissage en ligne (à distance) et sur la formation des étudiants en médecine, des résidents et du personnel enseignant. Nous avons inclus des articles de recherche originale et d’autres décrivant l’adaptation de contenus éducatifs à l’apprentissage en ligne. Résultats : Des 980 articles trouvés, nous avons sélectionné 208 études pour un examen du texte intégral et 100 articles pour une extraction de données. La plupart des travaux provenaient de pays occidentaux et ont été publiés dans des revues médicales. Le type de contenu adapté était principalement cognitif, dans une moindre mesure psychomoteur ou affectif. Plus de la moitié des articles présentaient un logiciel de visioconférence comme plateforme utilisée pour transposer des activités éducatives en mode virtuel. Malheureusement, la plupart des études ne précisaient pas les raisons justifiant le choix de plateforme. Celles qui l’ont fait indiquaient majoritairement que les solutions technologiques avaient été choisies en fonction de leur disponibilité au sein de l’établissement. De la même manière, seulement une poignée d’articles font état de l’utilisation d’une pédagogie, d’une théorie ou d’un cadre pour guider les adaptations pédagogiques

Quels liens entre les caractéristiques des médecins et leur cadre de pratique dans le contexte canadien : une étude de la portée

Background: Physician characteristics such as education and sociodemographic attributes are associated with particular practice patterns, such as practice in rural settings. Understanding the Canadian context of such associations can inform medical school recruitment and health workforce decision-making. Objective: The objective of this scoping review was to report the nature and extent of the literature on associations between characteristics of physicians in Canada and physicians’ practice patterns. Eligibility criteria: We included studies reporting associations between 1) the education or sociodemographic attributes of practicing physicians or residents in Canada and 2) practice patterns, including career choice, practice setting, and populations served. Methods: We searched five electronic databases (MEDLINE (R) ALL, Embase, ERIC, Education Source and Scopus) for quantitative primary studies and reviewed reference lists of included studies for additional studies. Data were extracted using a standardized data charting form. Results: Our search yielded 80 studies. Sixty-two examined education, evenly divided between undergraduate and postgraduate. Fifty-eight examined physicians’ attributes, most focusing on sex/gender. The majority of studies focused on the outcome of practice setting. We found no studies examining race/ethnicity or socioeconomic status. Conclusion: Many studies in our review found positive associations between (i) rural training or rural background and rural practice setting and (ii) location of training or physicians’ origin and practice in that location, consistent with previous literature. Associations for sex/gender were mixed, suggesting it may be a less useful target for workforce planning or recruitment aiming to address gaps in health care provision. More research is needed on the association of characteristics, particularly race/ethnicity and socioeconomic status, with career choice and populations served.Contexte : Il existe un lien entre les caractéristiques des médecins, comme leur formation et leur profil sociodémographique, et des cadres de pratique particuliers, comme la pratique en milieu rural. La compréhension de ces liens dans le contexte canadien peut éclairer les stratégies d’admission dans les facultés de médecine et la planification de la main-d’œuvre dans le secteur de la santé. Objectif : L’objectif de cette étude de la portée était de faire état de la nature et de l’étendue de la littérature sur les liens entre les caractéristiques des médecins au Canada et leurs cadres de pratique. Critères de sélection : Nous avons inclus les études établissant des liens entre 1) la formation ou le profil sociodémographique des médecins ou des résidents en exercice au Canada et 2) les cadres de pratique, y compris le choix de carrière, le milieu de pratique et les populations desservies. Méthodes : Nous avons effectué des recherches dans cinq bases de données électroniques (MEDLINE (R) ALL, Embase, ERIC, Education Source et Scopus) pour trouver des études quantitatives primaires et avons examiné les listes de références bibliographiques des articles inclus pour repérer d’autres études. Les données ont été extraites à l’aide d’un formulaire normalisé. Résultats : Notre recherche a permis de recenser 80 études. Soixante-deux d’entre elles portaient sur l’éducation, réparties de manière égale entre le premier cycle et le cycle de spécialisation. Cinquante-huit examinaient les caractéristiques des médecins, la plupart portant sur le sexe/genre. La majorité des études étaient focalisées sur le résultat lié au milieu de pratique. Nous n’avons trouvé aucune étude portant sur la race/ethnicité ou le statut socio-économique. Conclusion : Conformément à la littérature antérieure, de nombreuses études de notre revue trouvent des associations positives entre (i) la formation en milieu rural ou l’origine rurale et le cadre de pratique rurale et entre (ii) le lieu de formation ou l’origine des médecins et la pratique dans ce lieu. Les associations relatives au sexe/genre étaient mitigées, ce qui suggère qu’il s’agit peut-être d’une cible moins utile pour la planification ou le recrutement de la main-d’œuvre visant à combler les lacunes dans la prestation des soins de santé. Des recherches supplémentaires sont nécessaires sur les liens entre le profil des médecins, en particulier la race/ethnie, et le statut socio-économique, et leur choix de carrière et les populations desservies

Rééducation orthophonique post myoplastie d’allongement du temporal : une étude de trois patients

La myoplastie d’allongement du temporal est une chirurgie qui vise à restaurer le sourire chez les patients ayant une paralysie faciale périphérique irréversible. Le muscle temporal est détaché dans sa partie haute et rattaché à la commissure labiale. À la suite de la chirurgie, une rééducation orthophonique est nécessaire pour atteindre un sourire fonctionnel. Cette rééducation vise à automatiser le sourire pour le rendre spontané, ainsi qu’à optimiser le sourire pour rendre le mouvement de la commissure opérée symétrique à celui du côté sain. Parmi les moyens utilisés dans cette rééducation, un logiciel reproduisant l’hémiface saine permet de créer un effet-miroir, en offrant un biofeedback visuel positif aux patients. Les objectifs de la présente étude de cas multiples étaient 1) de mesurer les effets de la rééducation orthophonique après la myoplastie d’allongement du temporal et 2) de mesurer l’adhérence au traitement. Trois patients présentant une paralysie faciale périphérique droite secondaire à une résection de tumeur et ayant subi une myoplastie d’allongement du temporal ont été recrutés. Ces patients ont tous été évalués avant la chirurgie, ainsi qu’avant et après la rééducation, à l’aide de l’échelle Sunnybrook. Les résultats ont confirmé qu’à la suite de la rééducation orthophonique, le sourire des trois patients avait progressé.Compte tenu des résultats prometteurs obtenus avec cette rééducation, il serait intéressant d’en valider l’efficacité sur un plus grand nombre de patients.Lengthening temporalis myoplasty is a surgical procedure to restore the smile in patients with irreversible facial nerve paralysis. The temporalis muscle is detached from its upper end and attached to the labial commissure. Following surgery, facial rehabilitation by speech-language pathologists is necessary to achieve a functional smile. More specifically, this rehabilitation aims to automate the smile to make it spontaneous, as well as to optimize the smile to make the movement of the commissure operated on symmetrical to that of the healthy side. Among the means used in this rehabilitation, a software program reproducing the healthy hemiface allows for the creation of a “mirror effect” by giving the patients positive visual biofeedback. The objectives of this multiple case study were (a) to measure the effects of facial rehabilitation after lengthening temporalis myoplasty and (b) to measure adherence to treatment. Three patients with right facial nerve paralysis secondary to tumour resection that had lengthening temporalis myoplasty were enrolled. These patients were all assessed before surgery, and before and after rehabilitation, using the Sunnybrook scale. The results confirmed that following facial rehabilitation, the smiles of the three patients had improved. Given the promising results obtained from this rehabilitation, it would be interesting to validate its effectiveness on a larger number of patients

Characteristics of Canadian physicians and their associations with practice patterns: a scoping review

Background: Physician characteristics such as education and sociodemographic attributes are associated with particular practice patterns, such as practice in rural settings. Understanding the Canadian context of such associations can inform medical school recruitment and health workforce decision-making. Objective: The objective of this scoping review was to report the nature and extent of the literature on associations between characteristics of physicians in Canada and physicians’ practice patterns. Eligibility criteria: We included studies reporting associations between 1) the education or sociodemographic attributes of practicing physicians or residents in Canada and 2) practice patterns, including career choice, practice setting, and populations served. Methods: We searched five electronic databases (MEDLINE (R) ALL, Embase, ERIC, Education Source and Scopus) for quantitative primary studies and reviewed reference lists of included studies for additional studies. Data were extracted using a standardized data charting form. Results: Our search yielded 80 studies. Sixty-two examined education, evenly divided between undergraduate and postgraduate. Fifty-eight examined physicians’ attributes, most focusing on sex/gender. The majority of studies focused on the outcome of practice setting. We found no studies examining race/ethnicity or socioeconomic status. Conclusion: Many studies in our review found positive associations between (i) rural training or rural background and rural practice setting and (ii) location of training or physicians’ origin and practice in that location, consistent with previous literature. Associations for sex/gender were mixed, suggesting it may be a less useful target for workforce planning or recruitment aiming to address gaps in health care provision. More research is needed on the association of characteristics, particularly race/ethnicity and socioeconomic status, with career choice and populations served

Evaluation of intensive versus standard blood pressure reduction and association with cognitive decline and dementia : a systematic review and metaAnalysis

Importance: Optimal blood pressure (BP) targets for the prevention of cognitive impairment remain uncertain. Objective: To explore the association of intensive (i.e. lower than usual) BP reduction compared to guidelines on the incidence of cognitive decline and dementia in adults with hypertension. Data Sources and Study Selection: We conducted a systematic review and meta-analysis of randomized controlled trials that evaluated the association of intensive systolic BP lowering on cognitive outcomes by searching MEDLINE, Embase, CENTRAL, Web of Science, CINAHL, PsycINFO, ICTRP and ClinicalTrials.gov for data up to October 27, 2020. Data Extraction and Synthesis: Data screening and extraction were performed independently by two reviewers based on PRISMA guidelines. The risk of bias was assessed using the Cochrane risk-of-bias 2 tool. We used random-effects models using the inverse variance method for our pooled analyses. We evaluated the presence of potential heterogeneity with the I2 index. Main Outcomes and Measures: Our primary outcome was cognitive decline. Secondary outcomes included the incidence of dementia, mild cognitive impairment (MCI), cerebrovascular events, serious adverse events, and all-cause mortality. Results: From 7,755 citations, we identified sixteen publications from five trials (17,396 participants, mean age 65.7 years, 60.5% males) and two additional ongoing trials. All five trials included in quantitative analyses were considered at unclear to high risk of bias. The mean followup duration was 3.3 years (range 2.0 to 4.7 years). Intensive BP reduction was not significantly associated with global cognitive performance (SMD 0.01, 95% CI -0.04 to 0.06, I2 = 0%, four trials, 5,246 patients), incidence of dementia (RR 1.09, 95% CI 0.32 to 3.67, I2 = 27%, two trials, 9,444 patients) or incidence of MCI (RR 0.91, 95% CI 0.73 to 1.14, I2 = 74%, two trials, 10,774 patients) when compared to standard treatment. However, we found a reduction of cerebrovascular events in the intensive arm (RR 0.79, 95% CI 0.67-0.93, I2 = 0%, five trials, 17,396 patients) without an increased risk of serious adverse events or mortality. Conclusions and Relevance: We did not detect a significant association between BP reduction and lower risk of cognitive decline, dementia or MCI. The certainty of this evidence is low due to the limited sample size, the risk of bias of included trials and the observed statistical heterogeneity. Hence, current available evidence does not justify the use of lower BP targets for the prevention of cognitive decline and dementi

Spodoptera frugiperda (Lepidoptera: Noctuidae) host-plant variants: two host strains or two distinct species?

International audienceThe moth Spodoptera frugiperda is a well-known pest of crops throughout the Americas, which consists of two strains adapted to different host-plants: the first feeds preferentially on corn, cotton and sorghum whereas the second is more associated with rice and several pasture grasses. Though morphologically indistinguishable, they exhibit differences in their mating behavior, pheromone compositions, and show development variability according to the host-plant. Though the latter suggest that both strains are different species, this issue is still highly controversial because hybrids naturally occur in the wild, not to mention the discrepancies among published results concerning mating success between the two strains. In order to clarify the status of the two host-plant strains of S. frugiperda, we analyze features that possibly reflect the level of post-zygotic isolation: (1) first generation (F1) hybrid lethality and sterility; (2) patterns of meiotic segregation of hybrids in reciprocal second generation (F2), as compared to the meiosis of the two parental strains. We found a significant reduction of mating success in F1 in one direction of the cross and a high level of microsatellite markers showing transmission ratio distortion in the F2 progeny. Our results support the existence of post-zygotic reproductive isolation between the two laboratory strains and are in accordance with the marked level of genetic differentiation that was recovered between individuals of the two strains collected from the field. Altogether these results provide additional evidence in favor of a sibling species status for the two strains

A comparison of self-reported and device measured sedentary behaviour in adults: a systematic review and meta-analysis

© 2020 The Authors. Published by BMC. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1186/s12966-020-00938-3BACKGROUND:Sedentary behaviour (SB) is a risk factor for chronic disease and premature mortality. While many individual studies have examined the reliability and validity of various self-report measures for assessing SB, it is not clear, in general, how self-reported SB (e.g., questionnaires, logs, ecological momentary assessments (EMAs)) compares to device measures (e.g., accelerometers, inclinometers). OBJECTIVE:The primary objective of this systematic review was to compare self-report versus device measures of SB in adults. METHODS:Six bibliographic databases were searched to identify all studies which included a comparable self-report and device measure of SB in adults. Risk of bias within and across studies was assessed. Results were synthesized using meta-analyses. RESULTS:The review included 185 unique studies. A total of 123 studies comprising 173 comparisons and data from 55,199 participants were used to examine general criterion validity. The average mean difference was -105.19 minutes/day (95% CI: -127.21, -83.17); self-report underestimated sedentary time by ~1.74 hours/day compared to device measures. Self-reported time spent sedentary at work was ~40 minutes higher than when assessed by devices. Single item measures performed more poorly than multi-item questionnaires, EMAs and logs/diaries. On average, when compared to inclinometers, multi-item questionnaires, EMAs and logs/diaries were not significantly different, but had substantial amount of variability (up to 6 hours/day within individual studies) with approximately half over-reporting and half under-reporting. A total of 54 studies provided an assessment of reliability of a self-report measure, on average the reliability was good (ICC = 0.66). CONCLUSIONS:Evidence from this review suggests that single-item self-report measures generally underestimate sedentary time when compared to device measures. For accuracy, multi-item questionnaires, EMAs and logs/diaries with a shorter recall period should be encouraged above single item questions and longer recall periods if sedentary time is a primary outcome of study. Users should also be aware of the high degree of variability between and within tools. Studies should exert caution when comparing associations between different self-report and device measures with health outcomes. SYSTEMATIC REVIEW REGISTRATION:PROSPERO CRD42019118755.Dr. Stephanie Prince was funded by a Canadian Institutes of Health Research (CIHR) – Public Health Agency of Canada Health System Impact Fellowship. Dr. Jennifer Reed is funded, in part, by a CIHR New Investigator Salary Award. Dr. Jennifer Reed was awarded a Planning and Dissemination Grant (#150435) from the CIHR to support Open Access publication charges.Published versio