Résumé
L’adoption de politiques et de directives alimentaires dans les écoles canadiennes permet d’accroître l’offre et la consommation d’aliments riches en nutriments tout en réduisant l’accès à des ...aliments et des boissons riches en sucres, en sodium et en gras saturés. Ces politiques favorisent des changements positifs pour la santé des enfants et des adolescents, tels qu’un meilleur indice de masse corporelle. Cependant, elles ont des effets mitigés sur la performance scolaire. Le présent document de principes présente les principaux éléments des politiques alimentaires en milieu scolaire, notamment les normes nutritionnelles. Ces politiques doivent respecter les recommandations du Guide alimentaire canadien et promouvoir la consommation d’aliments et de boissons riches en nutriments, dont la teneur en gras saturé, en sucre et en sodium est plus faible.
Microglia are the resident macrophages of the CNS, and their functions have been extensively studied in various brain pathologies. The physiological roles of microglia in brain plasticity and ...function, however, remain unclear. To address this question, we generated CX3CR1CreER mice expressing tamoxifen-inducible Cre recombinase that allow for specific manipulation of gene function in microglia. Using CX3CR1CreER to drive diphtheria toxin receptor expression in microglia, we found that microglia could be specifically depleted from the brain upon diphtheria toxin administration. Mice depleted of microglia showed deficits in multiple learning tasks and a significant reduction in motor-learning-dependent synapse formation. Furthermore, Cre-dependent removal of brain-derived neurotrophic factor (BDNF) from microglia largely recapitulated the effects of microglia depletion. Microglial BDNF increases neuronal tropomyosin-related kinase receptor B phosphorylation, a key mediator of synaptic plasticity. Together, our findings reveal that microglia serve important physiological functions in learning and memory by promoting learning-related synapse formation through BDNF signaling.
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•CX3CR1CreER mice allow for the specific manipulation of microglial function•Microglia are important for learning and learning-dependent synaptic remodeling•Microglial BDNF is an important regulator of synaptic plasticity and function
Mice lacking microglia show defects in multiple learning tasks, with microglia-derived brain-derived neurotrophic factor being a critical factor for learning-dependent synaptic plasticity.
Optional stopping refers to the practice of peeking at data and then, based on the results, deciding whether or not to continue an experiment. In the context of ordinary significance-testing ...analysis, optional stopping is discouraged, because it necessarily leads to increased type I error rates over nominal values. This article addresses whether optional stopping is problematic for Bayesian inference with Bayes factors. Statisticians who developed Bayesian methods thought not, but this wisdom has been challenged by recent simulation results of Yu, Sprenger, Thomas, and Dougherty (
2013
) and Sanborn and Hills (
2013
). In this article, I show through simulation that the interpretation of Bayesian quantities does not depend on the stopping rule. Researchers using Bayesian methods may employ optional stopping in their own research and may provide Bayesian analysis of secondary data regardless of the employed stopping rule. I emphasize here the proper interpretation of Bayesian quantities as measures of subjective belief on theoretical positions, the difference between frequentist and Bayesian interpretations, and the difficulty of using frequentist intuition to conceptualize the Bayesian approach.
•Medical image segmentation typically faces limited datasets.•Dataset limitations are broadly grouped into scarce and weak annotations.•Scarce annotations can be addressed proactively via ...cost-effective annotation or by leveraging external labeled or unlabeled datasets.•Scarce annotations can be addressed reactively via various forms of conditional random fields as post processing.•Weak annotations may manifest as sparse, noisy, or only image-level labels.•Sparse and noisy annotations can leveraged via selective and noise-resilient loss functions, respectively.•Image-level labels can leveraged via various forms of class activation maps.•Recommended solutions based on a cost-gain trade-off are provided.
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The medical imaging literature has witnessed remarkable progress in high-performing segmentation models based on convolutional neural networks. Despite the new performance highs, the recent advanced segmentation models still require large, representative, and high quality annotated datasets. However, rarely do we have a perfect training dataset, particularly in the field of medical imaging, where data and annotations are both expensive to acquire. Recently, a large body of research has studied the problem of medical image segmentation with imperfect datasets, tackling two major dataset limitations: scarce annotations where only limited annotated data is available for training, and weak annotations where the training data has only sparse annotations, noisy annotations, or image-level annotations. In this article, we provide a detailed review of the solutions above, summarizing both the technical novelties and empirical results. We further compare the benefits and requirements of the surveyed methodologies and provide our recommended solutions. We hope this survey article increases the community awareness of the techniques that are available to handle imperfect medical image segmentation datasets.
The energy released in solar flares derives from a reconfiguration of magnetic fields to a lower energy state, and is manifested in several forms, including bulk kinetic energy of the coronal mass ...ejection, acceleration of electrons and ions, and enhanced thermal energy that is ultimately radiated away across the electromagnetic spectrum from optical to x rays. Using an unprecedented set of coordinated observations, from a suite of instruments, we here report on a hitherto largely overlooked energy component-the kinetic energy associated with small-scale turbulent mass motions. We show that the spatial location of, and timing of the peak in, turbulent kinetic energy together provide persuasive evidence that turbulent energy may play a key role in the transfer of energy in solar flares. Although the kinetic energy of turbulent motions accounts, at any given time, for only ∼(0.5-1)% of the energy released, its relatively rapid (∼1-10 s) energization and dissipation causes the associated throughput of energy (i.e., power) to rival that of major components of the released energy in solar flares, and thus presumably in other astrophysical acceleration sites.
Oral cavity carcinoma (OCC) remains a major cause of morbidity and mortality in patients with head and neck cancer. Although the incidence has decreased over the last decade, outcomes remain stagnant ...with only a 5% improvement in overall survival in the last 20 years. Although surgical resection remains the primary treatment modality, several areas of controversy exist with regard to work-up, management of the primary and neck tumors, and adjuvant therapy. As surgical techniques evolve, so has the delivery of radiotherapy and systemic treatment, which have helped to improve the outcomes for patients with advanced disease. Recently, the addition of cetuximab has shown promise as a way to improve outcomes while minimizing toxicity, and this remains an active area of study in the adjuvant setting. Advances in microvascular free-flap reconstruction have extended the limits of resection and enabled enhanced restoration of function and cosmesis. While these advances have led to limited survival benefit, evaluation of alternative modalities has gained interest on the basis of success in other head and neck subsites. Organ preservation with definitive chemoradiotherapy, though proven in the larynx and pharynx, remains controversial in OCC. Likewise, although the association of human papillomavirus is well established in oropharyngeal carcinoma, it has not been proven in the pathogenesis or survival of OCC. Future study of the molecular biology and pathogenesis of OCC should offer additional insight into screening, treatment selection, and novel therapeutic approaches.
Osteoarthritis (OA) is the most common joint disease, affecting an estimated more than 240 million people worldwide, including an estimated more than 32 million in the US. Osteoarthritis is the most ...frequent reason for activity limitation in adults. This Review focuses on hip and knee OA.
Osteoarthritis can involve almost any joint but typically affects the hands, knees, hips, and feet. It is characterized by pathologic changes in cartilage, bone, synovium, ligament, muscle, and periarticular fat, leading to joint dysfunction, pain, stiffness, functional limitation, and loss of valued activities, such as walking for exercise and dancing. Risk factors include age (33% of individuals older than 75 years have symptomatic and radiographic knee OA), female sex, obesity, genetics, and major joint injury. Persons with OA have more comorbidities and are more sedentary than those without OA. The reduced physical activity leads to a 20% higher age-adjusted mortality. Several physical examination findings are useful diagnostically, including bony enlargement in knee OA and pain elicited with internal hip rotation in hip OA. Radiographic indicators include marginal osteophytes and joint space narrowing. The cornerstones of OA management include exercises, weight loss if appropriate, and education-complemented by topical or oral nonsteroidal anti-inflammatory drugs (NSAIDs) in those without contraindications. Intra-articular steroid injections provide short-term pain relief and duloxetine has demonstrated efficacy. Opiates should be avoided. Clinical trials have shown promising results for compounds that arrest structural progression (eg, cathepsin K inhibitors, Wnt inhibitors, anabolic growth factors) or reduce OA pain (eg, nerve growth factor inhibitors). Persons with advanced symptoms and structural damage are candidates for total joint replacement. Racial and ethnic disparities persist in the use and outcomes of joint replacement.
Hip and knee OA are highly prevalent and disabling. Education, exercise and weight loss are cornerstones of management, complemented by NSAIDs (for patients who are candidates), corticosteroid injections, and several adjunctive medications. For persons with advanced symptoms and structural damage, total joint replacement effectively relieves pain.
Corporate governance is on the reform agenda all over the world. How will global economic integration affect the different systems of corporate ownership and governance? Is the Anglo-American model ...of shareholder capitalism destined to become the template for a converging global corporate governance standard or will the differences persist? This reader contains classic work from leading scholars addressing this question as well as several new essays. In a sophisticated political economy analysis that is also attuned to the legal framework, the authors bring to bear efficiency arguments, politics, institutional economics, international relations, industrial organization, and property rights. These questions have become even more important in light of the post-Enron corporate governance crisis in the United States and the European Union's repeated efforts at corporate integration. This will become a key text for postgraduates and academics.
Intracellular proteins with long lifespans have recently been linked to age-dependent defects, ranging from decreased fertility to the functional decline of neurons. Why long-lived proteins exist in ...metabolically active cellular environments and how they are maintained over time remains poorly understood. Here, we provide a system-wide identification of proteins with exceptional lifespans in the rat brain. These proteins are inefficiently replenished despite being translated robustly throughout adulthood. Using nucleoporins as a paradigm for long-term protein persistence, we found that nuclear pore complexes (NPCs) are maintained over a cell’s life through slow but finite exchange of even its most stable subcomplexes. This maintenance is limited, however, as some nucleoporin levels decrease during aging, providing a rationale for the previously observed age-dependent deterioration of NPC function. Our identification of a long-lived proteome reveals cellular components that are at increased risk for damage accumulation, linking long-term protein persistence to the cellular aging process.
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•Metabolic pulse-chase labeling of rats identified long-lived proteins in rats•Long-lived proteins include nucleoporins, histone variants, and enzymes•Long-lived proteins cannot be replaced despite their robust translation•Nuclear pores are maintained over the lifespan of the organism
A system-wide identification of proteins with exceptional lifespans in the rat brain suggests that these have a higher propensity for damage. Cells utilize specific mechanisms to ensure that such proteins are maintained in a functional state through aging.
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