36 research outputs found

    The Effect of Tracking Students by Ability into Different Schools: A Natural Experiment

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    The tracking of pupils by ability into elite and non-elite schools represents a controversial policy in many countries. There is no consensus on how large the elite track should be and little agreement on the effects of any further increase in its size. This paper presents a natural experiment where the increase in the size of the elite track was followed by a significant improvement in average educational outcomes. This experiment provides a rare opportunity to isolate the overall effect of allowing entry to the elite track for a group that was previously only at the margin of being admitted.Education, Tracking, Selection

    Biased Aspirations and Social Inequality at School: Evidence from French Teenagers

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    This paper provides empirical evidence on how aspirations are formed and affect individual behavior, decisions, and paths in the context of education. Using unique data on aspirations, academic performance and actual track assignment to high school of French ninth graders, we show that low-SES students have lower aspirations than their equally-achieving high-SES classmates, and that track assignments to high school the next year are even more unequal due to dysfunctional dynamics: first, both low aspirations and low SES are associated with slower academic progress over the year. Second, aspirations and parental SES play a role in track assignment independent of one’s academic performance. Our results suggest that, in France, an aspirational trap at school contributes to the poverty trap, leading to the perpetuation of social inequalities

    Track choice and socio-economic origin: measuring and explaining academic inhibition

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    Pupils from modest socio-economic backgrounds choose less selective academic tracks than others at the same level of ability. Pupils from more modest backgrounds underestimate their own ability; they believe that they are less likely to succeed in a selective academic track, and they have a tendency to conform to the choices of their peers. In addition, outside influence (from the parents or school) over the course of the last year of junior high tends to exacerbate the gap for weaker students, but narrow the gap for stronger students. We propose specific policy interventions based on these findings.Les élèves d’origine sociale modeste aspirent à des filières académiques moins sélectives que leurs pairs de même niveau scolaire mais d’origine sociale favorisée. Plusieurs raisons sont mises à jour : premièrement, les élèves d’origine modeste sous­-estiment leurs capacités scolaires actuelles par rapport aux élèves d’origine favorisée ; ensuite, ils anticipent une forte différence dans leurs chances de succès dans le futur ; en outre, ils ont tendance à se conformer à leurs pairs. Par ailleurs, l’action des parents et des enseignants dans le processus d’orientation tend à accroître ces inégalités d’aspirations pour les élèves faibles, tandis qu’elle réduit ces inégalités pour les élèves au-­dessus de la médiane. Ces résultats permettent de proposer des pistes d’interventions permettant de réduire les inégalités sociales d’aspirations scolaires

    Comment lutter contre la violence et le harcĂšlement Ă  l’école et au collĂšge ?:Effets du dispositif de mĂ©diation sociale France MĂ©diation et d’un dispositif de prise de conscience du niveau de violence

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    L’équipe de recherche du LIEPP a conduit sur la pĂ©riode 2012-2014 l’évaluation, selon un protocole expĂ©rimental par assignation alĂ©atoire, de deux dispositifs de lutte contre le harcĂšlement au collĂšge et Ă  l’école primaire. Le premier programme, dit « MĂ©diation Sociale en Milieu Scolaire », consiste en le dĂ©ploiement de 40 mĂ©diateurs dont la mission est de prĂ©venir et rĂ©guler la violence par des actions de mĂ©diation sociale au sein de 40 sites scolaires. L’évaluation du programme s’est attachĂ©e Ă  croiser l’ensemble des perspectives Ă©lĂšves, Ă©quipes Ă©ducatives et parents. Les rĂ©sultats divergent selon que l’on s’intĂ©resse aux collĂšges ou aux Ă©coles. Au collĂšge, l’évaluation montre que si les effets du programme sont faibles et peu significatifs au niveau global, ils sont en revanche trĂšs importants lorsqu’il est mis en place par des mĂ©diateurs expĂ©rimentĂ©s. Dans ce cas, le programme rĂ©duit de 11% le taux de harcĂšlement ressenti par l’ensemble des collĂ©giens, avec en particulier une rĂ©duction significative du harcĂšlement verbal de 15% (moqueries, surnoms mĂ©chants). Plus fondamentalement, ces effets « moyens » cachent d’importantes disparitĂ©s selon la classe d’ñge et le genre. A l’école, les effets du programme sont plus mitigĂ©s : en moyenne, le programme n’a pas d’effet significatif sur les niveaux de harcĂšlement et de violence dĂ©clarĂ©s par les Ă©lĂšves, mĂȘme lorsque le dispositif est portĂ© par des mĂ©diateurs expĂ©rimentĂ©s. Le second programme Ă©valuĂ©, dit « Prise de conscience », consiste en la passation d’une enquĂȘte de victimation et en la restitution des rĂ©sultats Ă  l’établissement afin de sensibiliser l’équipe Ă©ducative Ă  la problĂ©matique de la violence scolaire. L’évaluation d’impact montre que ce programme n’a pas d’effet significatif sur le harcĂšlement et la violence dĂ©clarĂ©s par les Ă©lĂšves, ni sur leur bien-ĂȘtre, leurs performances scolaires ou encore leur comportement. Ce rĂ©sultat est identique que l’enquĂȘte de victimation soit accompagnĂ©e ou non d’une restitution collective auprĂšs du personnel de l’établissement

    Comment lutter contre la violence et le harcÚlement à l'école et au collÚge ?:Enseignements d'une expérimentation à grande échelle

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    La violence entre pairs Ă  l’école est un phĂ©nomĂšne prĂ©occupant, en particulier compte tenu du potentiel impact de long terme sur le devenir des enfants. Nous Ă©valuons ici les effets d’un dispositif de « MĂ©diation Sociale en Milieu Scolaire » (MSMS) visant Ă  rĂ©duire la violence entre pairs. GrĂące Ă  un protocole expĂ©rimental par assignation alĂ©atoire, nous montrons que les effets du programme sont trĂšs importants lorsqu’il est mis en place par des mĂ©diateurs assez expĂ©rimentĂ©s : au collĂšge, le taux de harcĂšlement ressenti est alors rĂ©duit de 11%. PrĂ©cisĂ©ment, le programme est extrĂȘmement bĂ©nĂ©fique pour les Ă©lĂšves les plus exposĂ©s Ă  la violence : ainsi la probabilitĂ© de se sentir harcelĂ© diminue de 46% chez les garçons de 6Ăšme et de 26% chez les filles de 5Ăšme. Des effets intĂ©ressants sont Ă©galement visibles sur le bien­ĂȘtre psychologique et social des Ă©lĂšves, ainsi que sur l’absentĂ©isme des Ă©lĂšves et des enseignants.Peer violence in schools is a worrying phenomenon, especially the potential longterm impact it may have on a child’s future. Here we evaluate the effects of a program of social mediation at school implemented to reduce peer violence. Through a randomized experimental design, we show that the effects of the program are very important when it is implemented by mediators who are over 25 years old: in junior high school, the rate of experienced harassment is reduced by 11%. Specifically, the program is extremely beneficial for students most exposed to violence: the probability of feeling harassed decreased by 46% in boys in 6th grade and by 26% in girls in 7th grade. Interesting effects on the psychological and social well­being of students, as well as on student absenteeism and teachers are also visible

    Effective selection of informative SNPs and classification on the HapMap genotype data

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    <p>Abstract</p> <p>Background</p> <p>Since the single nucleotide polymorphisms (SNPs) are genetic variations which determine the difference between any two unrelated individuals, the SNPs can be used to identify the correct source population of an individual. For efficient population identification with the HapMap genotype data, as few informative SNPs as possible are required from the original 4 million SNPs. Recently, Park <it>et al.</it> (2006) adopted the nearest shrunken centroid method to classify the three populations, i.e., Utah residents with ancestry from Northern and Western Europe (CEU), Yoruba in Ibadan, Nigeria in West Africa (YRI), and Han Chinese in Beijing together with Japanese in Tokyo (CHB+JPT), from which 100,736 SNPs were obtained and the top 82 SNPs could completely classify the three populations.</p> <p>Results</p> <p>In this paper, we propose to first rank each feature (SNP) using a ranking measure, i.e., a modified t-test or F-statistics. Then from the ranking list, we form different feature subsets by sequentially choosing different numbers of features (e.g., 1, 2, 3, ..., 100.) with top ranking values, train and test them by a classifier, e.g., the support vector machine (SVM), thereby finding one subset which has the highest classification accuracy. Compared to the classification method of Park <it>et al.</it>, we obtain a better result, i.e., good classification of the 3 populations using on average 64 SNPs.</p> <p>Conclusion</p> <p>Experimental results show that the both of the modified t-test and F-statistics method are very effective in ranking SNPs about their classification capabilities. Combined with the SVM classifier, a desirable feature subset (with the minimum size and most informativeness) can be quickly found in the greedy manner after ranking all SNPs. Our method is able to identify a very small number of important SNPs that can determine the populations of individuals.</p

    Identification of a Kinase Profile that Predicts Chromosome Damage Induced by Small Molecule Kinase Inhibitors

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    Kinases are heavily pursued pharmaceutical targets because of their mechanistic role in many diseases. Small molecule kinase inhibitors (SMKIs) are a compound class that includes marketed drugs and compounds in various stages of drug development. While effective, many SMKIs have been associated with toxicity including chromosomal damage. Screening for kinase-mediated toxicity as early as possible is crucial, as is a better understanding of how off-target kinase inhibition may give rise to chromosomal damage. To that end, we employed a competitive binding assay and an analytical method to predict the toxicity of SMKIs. Specifically, we developed a model based on the binding affinity of SMKIs to a panel of kinases to predict whether a compound tests positive for chromosome damage. As training data, we used the binding affinity of 113 SMKIs against a representative subset of all kinases (290 kinases), yielding a 113×290 data matrix. Additionally, these 113 SMKIs were tested for genotoxicity in an in vitro micronucleus test (MNT). Among a variety of models from our analytical toolbox, we selected using cross-validation a combination of feature selection and pattern recognition techniques: Kolmogorov-Smirnov/T-test hybrid as a univariate filter, followed by Random Forests for feature selection and Support Vector Machines (SVM) for pattern recognition. Feature selection identified 21 kinases predictive of MNT. Using the corresponding binding affinities, the SVM could accurately predict MNT results with 85% accuracy (68% sensitivity, 91% specificity). This indicates that kinase inhibition profiles are predictive of SMKI genotoxicity. While in vitro testing is required for regulatory review, our analysis identified a fast and cost-efficient method for screening out compounds earlier in drug development. Equally important, by identifying a panel of kinases predictive of genotoxicity, we provide medicinal chemists a set of kinases to avoid when designing compounds, thereby providing a basis for rational drug design away from genotoxicity

    Lactate dehydrogenases promote glioblastoma growth and invasion via a metabolic symbiosis

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    Lactate is a central metabolite in brain physiology but also contributes to tumor development. Glioblastoma (GB) is the most common and malignant primary brain tumor in adults, recognized by angiogenic and invasive growth, in addition to its altered metabolism. We show herein that lactate fuels GB anaplerosis by replenishing the tricarboxylic acid (TCA) cycle in absence of glucose. Lactate dehydrogenases (LDHA and LDHB), which we found spatially expressed in GB tissues, catalyze the interconversion of pyruvate and lactate. However, ablation of both LDH isoforms, but not only one, led to a reduction in tumor growth and an increase in mouse survival. Comparative transcriptomics and metabolomics revealed metabolic rewiring involving high oxidative phosphorylation (OXPHOS) in the LDHA/B KO group which sensitized tumors to cranial irradiation, thus improving mouse survival. When mice were treated with the antiepileptic drug stiripentol, which targets LDH activity, tumor growth decreased. Our findings unveil the complex metabolic network in which both LDHA and LDHB are integrated and show that the combined inhibition of LDHA and LDHB strongly sensitizes GB to therapy.publishedVersio

    Perspectives from the NanoSafety Modelling Cluster on the validation criteria for (Q)SAR models used in nanotechnology

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    Nanotechnology and the production of nanomaterials have been expanding rapidly in recent years. Since many types of engineered nanoparticles are suspected to be toxic to living organisms and to have a negative impact on the environment, the process of designing new nanoparticles and their applications must be accompanied by a thorough exposure risk analysis. (Quantitative) Structure-Activity Relationship ([Q]SAR) modelling creates promising options among the available methods for the risk assessment. These in silico models can be used to predict a variety of properties, including the toxicity of newly designed nanoparticles. However, (Q)SAR models must be appropriately validated to ensure the clarity, consistency and reliability of predictions. This paper is a joint initiative from recently completed European research projects focused on developing (Q)SAR methodology for nanomaterials. The aim was to interpret and expand the guidance for the well-known “OECD Principles for the Validation, for Regulatory Purposes, of (Q)SAR Models”, with reference to nano-(Q)SAR, and present our opinions on the criteria to be fulfilled for models developed for nanoparticles

    Etude des effets de la rĂ©novation urbaine sur l’évolution du bĂąti et du peuplement dans les quartiers ciblĂ©s entre 2004 et 2013

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    Alors que l’Etat s’apprĂȘte Ă  investir 20 milliards d’euros dans le Nouveau Programme National de Renouvellement Urbain (NPNRU), le LIEPP publie son rapport sur les effets de son prĂ©dĂ©cesseur, le Programme National pour la RĂ©novation Urbaine (PNRU), mis en Ɠuvre depuis 2004. Cette Ă©tude a Ă©tĂ© rĂ©alisĂ©e dans le cadre d’un partenariat de recherche entre le LIEPP Sciences Po - en la personne de Nina Guyon - et le Commissariat gĂ©nĂ©ral Ă  l’égalitĂ© des territoires (CGET). Elle repose sur l’exploitation des donnĂ©es CGDD-SOeS Filocom dĂ©tenues par le Service de l’Observation et des Statistiques (SOeS) du ministĂšre de l’écologie, du dĂ©veloppement durable et de l’énergie. L’étude a reçu l’appui financier direct de la National University of Singapore (Ă  hauteur de 85%) et du Commissariat GĂ©nĂ©ral Ă  l’EgalitĂ© des Territoires (Ă  hauteur de 15%)
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