36 research outputs found
The Effect of Tracking Students by Ability into Different Schools: A Natural Experiment
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
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 oneâs 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
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 eÌleÌves dâorigine sociale modeste aspirent aÌ des filieÌres acadeÌmiques moins seÌlectives que leurs pairs de meÌme niveau scolaire mais dâorigine sociale favoriseÌe. Plusieurs raisons sont mises aÌ jour : premieÌrement, les eÌleÌves dâorigine modeste sousÂ-estiment leurs capaciteÌs scolaires actuelles par rapport aux eÌleÌves dâorigine favoriseÌe ; ensuite, ils anticipent une forte diffeÌrence dans leurs chances de succeÌs dans le futur ; en outre, ils ont tendance aÌ se conformer aÌ leurs pairs. Par ailleurs, lâaction des parents et des enseignants dans le processus dâorientation tend aÌ accroiÌtre ces ineÌgaliteÌs dâaspirations pour les eÌleÌves faibles, tandis quâelle reÌduit ces ineÌgaliteÌs pour les eÌleÌves au-Âdessus de la meÌdiane. Ces reÌsultats permettent de proposer des pistes dâinterventions permettant de reÌduire les ineÌgaliteÌs sociales dâaspirations scolaires
Comment lutter contre la violence et le harcĂšlement Ă lâĂ©cole et au collĂšge ?:Effets du dispositif de mĂ©diation sociale France MĂ©diation et dâun dispositif de prise de conscience du niveau de violence
LâĂ©quipe de recherche du LIEPP a conduit sur la pĂ©riode 2012-2014 lâĂ©valuation, selon un protocole expĂ©rimental par assignation alĂ©atoire, de deux dispositifs de lutte contre le harcĂšlement au collĂšge et Ă lâĂ©cole 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. LâĂ©valuation du programme sâest attachĂ©e Ă croiser lâensemble des perspectives Ă©lĂšves, Ă©quipes Ă©ducatives et parents. Les rĂ©sultats divergent selon que lâon sâintĂ©resse aux collĂšges ou aux Ă©coles. Au collĂšge, lâĂ©valuation montre que si les effets du programme sont faibles et peu significatifs au niveau global, ils sont en revanche trĂšs importants lorsquâil 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 lâensemble 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 dâimportantes disparitĂ©s selon la classe dâĂąge et le genre. A lâĂ©cole, les effets du programme sont plus mitigĂ©s : en moyenne, le programme nâa pas dâeffet 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 dâune enquĂȘte de victimation et en la restitution des rĂ©sultats Ă lâĂ©tablissement afin de sensibiliser lâĂ©quipe Ă©ducative Ă la problĂ©matique de la violence scolaire. LâĂ©valuation dâimpact montre que ce programme nâa pas dâeffet 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 lâenquĂȘte de victimation soit accompagnĂ©e ou non dâune restitution collective auprĂšs du personnel de lâĂ©tablissement
Comment lutter contre la violence et le harcÚlement à l'école et au collÚge ?:Enseignements d'une expérimentation à grande échelle
La violence entre pairs Ă lâĂ©cole 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 dâun dispositif de « MĂ©diation Sociale en Milieu Scolaire »
(MSMS) visant à réduire la violence entre pairs. Grùce à un protocole
expérimental par assignation aléatoire, nous montrons que les effets du
programme sont trĂšs importants lorsquâil est mis en place par des mĂ©diateurs
assez expérimentés : au collÚge, le taux de harcÚlement ressenti est alors réduit
de 11%. PrĂ©cisĂ©ment, le programme est extrĂȘmement bĂ©nĂ©fique pour les Ă©lĂšves
les plus exposés à la violence : ainsi la probabilité de se sentir harcelé diminue
de 46% chez les garçons de 6Úme et de 26% chez les filles de 5Úme. Des effets
intĂ©ressants sont Ă©galement visibles sur le bienÂĂȘtre psychologique et social des
Ă©lĂšves, ainsi que sur lâabsentĂ©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 childâs 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 wellÂbeing 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
<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
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 113Ă290 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
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
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 âOECD Principles for the Validation, for Regulatory Purposes, of (Q)SAR Modelsâ, 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 lâĂ©volution du bĂąti et du peuplement dans les quartiers ciblĂ©s entre 2004 et 2013
Alors que lâEtat sâapprĂȘte Ă investir 20 milliards dâeuros 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 Ćuvre depuis 2004. Cette Ă©tude a Ă©tĂ© rĂ©alisĂ©e dans le cadre dâun partenariat de recherche entre le LIEPP Sciences Po - en la personne de Nina Guyon - et le Commissariat gĂ©nĂ©ral Ă lâĂ©galitĂ© des territoires (CGET). Elle repose sur lâexploitation des donnĂ©es CGDD-SOeS Filocom dĂ©tenues par le Service de lâObservation et des Statistiques (SOeS) du ministĂšre de lâĂ©cologie, du dĂ©veloppement durable et de lâĂ©nergie. LâĂ©tude a reçu lâappui financier direct de la National University of Singapore (Ă hauteur de 85%) et du Commissariat GĂ©nĂ©ral Ă lâEgalitĂ© des Territoires (Ă hauteur de 15%)