The paradoxical role of meritocratic selection in the perpetuation of social inequalities at school

The school system is intended to offer all students the same opportunities, but most international surveys reveal an overall lower achievement for students from disadvantaged groups compared with more advantaged students. Recent experimental research in social psychology has demonstrated that schools as institutions contribute with their implicit cultural norms and structure to the production of inequalities. This chapter examines the role that a structural feature of school, namely meritocratic selection, plays in this reproduction of inequalities at school. First, we describe how meritocracy in the educational system can hold paradoxical effects by masking the virtuous/vicious cycles of opportunities created by educational institutions. Second, we present recent research suggesting that selection practices relying on a meritocratic principle—more than other practices—can lead to biased academic decisions hindering disadvantaged students. We propose that inequalities in school might not just result from isolated failures in an otherwise functional meritocratic system, but rather that merit-based selection itself contributes to the perpetuation of inequalities at school

Bodemvruchtbaarheid : bemestingsstrategie voor vruchtbare en levende bodem, verslag 2005

Van 2002 tot eind 2005 is door het Louis Bolk Instituut onderzoek verricht op zeven biologische glasgroente bedrijven. Dit verslag heeft betrekking op met name 2005, maar waar nodig zijn ook eerdere onderzoeksresultaten in dit verslag verwerkt. Aan de orde komen: bemesting, mineralenbalansen en de toepassing van de nieuwe bemestingsrichtlijn. Daarnaast is er aandacht voor de bodemstructuur (toplaag 0-25 cm en onderlaag 25-50cm), voedselwebben, en ziektewerendheid van kasgronden (Fusarium als toets)

A novel tool to evaluate the implant position and predict defibrillation success of the subcutaneous implantable cardioverter-defibrillator: The PRAETORIAN score

Background: Suboptimal positioning of the subcutaneous implantable cardioverter-defibrillator (S-ICD) increases the defibrillation threshold and risk of conversion failure. Objective: Our objective is to develop a tool to evaluate the implant position and predict defibrillation success of the S-ICD: the PRAETORIAN score. Methods: The PRAETORIAN score is based on clinical and computer modeling knowledge of determinants affecting the defibrillation threshold: subcoil fat, subgenerator fat, and anterior positioning of the S-ICD generator. The score evaluates these determinants on the postoperative anterior-posterior and lateral chest radiographs and has 3 categories: 30–<90 points representing a low risk, 90–<150 points representing an intermediate risk, and ≥150 points representing a high risk of conversion failure. The score was developed using 2 separate S-ICD data sets for derivation and validation. The performance metrics are the positive and negative predictive values. Results: The development data set consisted of 181 patients with S-ICD, and the validation cohort consisted of 321 patients from the S-ICD Investigational Device Exemption trial. The distribution of scores was 93%–98% low risk (<90 points), 2%–5% intermediate risk (90–<150 points), and 1% high risk (≥150 points). The positive predictive value for an intermediate or high PRAETORIAN score for a failed conversion test was 51%, while a low PRAETORIAN score predicted a successful conversion in 99.8% of patients. Conclusion: The PRAETORIAN score allows the identification of patients with high defibrillation thresholds by using the routine chest radiograph and provides feedback to implanters on S-ICD positioning. The PRAETORIAN-DFT trial will prospectively validate the score by randomizing to standard conversion testing vs using the score without conversion testing

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Rationale and design of the PRAETORIAN-DFT trial: A prospective randomized CompArative trial of SubcutanEous ImplanTable CardiOverter-DefibrillatoR ImplANtation with and without DeFibrillation testing

In transvenous implantable cardioverter-defibrillator (TV-ICD) implants, routine defibrillation testing (DFT) does not improve shock efficacy or reduce arrhythmic death but patients are exposed to the risk of complications related to DFT. The conversion rate of DFT in subcutaneous ICD (S-ICD) is high and first shock efficacy is similar to TV-ICD efficacy rates. Study Design: The PRAETORIAN-DFT trial is an investigator-initiated, randomized, controlled, multicenter, prospective two-arm trial designed to demonstrate non-inferiority of omitting DFT in patients undergoing S-ICD implantation in which the S-ICD system components are optimally positioned. Positioning of the S-ICD will be assessed with the PRAETORIAN score. The PRAETORIAN score is developed to systematically evaluate implant position of the S-ICD system components which determine the defibrillation threshold on post-operative chest X-ray. A total of 965 patients, scheduled to undergo a de novo S-ICD implantation without contra-indications for either DFT strategy, will be randomized to either standard of care S-ICD implantation with DFT, or S-ICD implantation without DFT but with evaluation of the implant position using the PRAETORIAN score. The study is powered to claim non-inferiority of S-ICD implantation without DFT in de novo S-ICD patients in respect to the primary endpoint of first shock efficacy in spontaneous arrhythmia episodes. Patients with a high PRAETORIAN score (≥90) in the interventional arm of this study will undergo DFT according to the same DFT protocol as in the control arm. Conclusion: The PRAETORIAN-DFT trial is a randomized trial that aims to gain scientific evidence to safely omit a routine DFT after S-ICD implantation in patients with correct device positioning

Looking with the (computer) mouse: How to unveil problem-solving strategies in matrix reasoning without eye-tracking

International audienceProblem-solving strategies in visual reasoning tasks are often studied based on the analysis of eye movements, which yields high-quality data but is costly and difficult to implement on a large scale. We devised a new graphical user interface for matrix reasoning tasks where the analysis of computer mouse movements makes it possible to investigate item exploration and, in turn, problem-solving strategies. While relying on the same active perception principles underlying eye-tracking (ET) research, this approach has the additional advantages of being user-friendly and easy to implement in real-world testing conditions, and records only voluntary decisions. A pilot study confirmed that embedding items of Raven's Advanced Progressive Matrices (APM) in the interface did not significantly alter its psychometric properties. Experiment 1 indicated that mouse-based exploration indices, when used to assess two major problem-solving strategies in the APM, are related to final performance—as has been found in past ET research. Experiment 2 suggested that constraining some features of the interface favored the adoption of the more efficient solving strategy for some participants. Overall, the findings support the relevance of the present methodology for accessing and manipulating problem-solving strategies

Ethical issues raised by proposals to treat addiction using deep brain stimulation

Deep brain stimulation (DBS) has been proposed as a potential treatment of drug addiction on the basis of its effects on drug self-administration in animals and on addictive behaviours in some humans treated with DBS for other psychiatric or neurological conditions. DBS is seen as a more reversible intervention than ablative neurosurgery but it is nonetheless a treatment that carries significant risks. A review of preclinical and clinical evidence for the use of DBS to treat addiction suggests that more animal research is required to establish the safety and efficacy of the technology and to identify optimal treatment parameters before investigating its use in addicted persons. Severely addicted persons who try and fail to achieve abstinence may, however, be desperate enough to undergo such an invasive treatment if they believe that it will cure their addiction. History shows that the desperation for a "cure" of addiction can lead to the use of risky medical procedures before they have been rigorously tested. In the event that DBS is used in the treatment of addiction, we provide minimum ethical requirements for clinical trials of its use in the treatment of addiction. These include: restrictions of trials to severely intractable cases of addiction; independent oversight to ensure that patients have the capacity to consent and give that consent on the basis of a realistic appreciation of the potential benefits and risks of DBS; and rigorous assessments of the effectiveness and safety of this treatment compared to the best available treatments for addiction. © 2010 Springer Science+Business Media B.V