L’évolution des enfants difficiles

Dans cet article, les auteurs relatent une recherche faite, dans le cadre du projet Concordia Longitudinal Risk Project, sur l'ajustement des enfants socialement atypiques durant l'adolescence. Plus précisément, ils tentent de répondre à la question suivante: Quels comportements de l'enfant et quelles tangentes de son développement mènent à des problèmes psychologiques majeurs à l'adolescence et à l'âge adulte? Après une analyse complexe de divers facteurs, leurs résultats indiquent que les enfants perçus comme agressifs, repliés sur eux-mêmes ou souvent agressifs et repliés sur eux-mêmes par leur camarades, sont susceptibles d'avoir des problèmes à l'adolescence. Ils explicitent ensuite selon ces trois groupes les difficultés de chacun.In this article, the authors discuss a study carried out during a Concordia Longitudinal Risk Project that deals with the adjustment of socially atypical children in their adolescent years. More precisely, they try to answer the following question : What child behaviors and which tangents of their development lead to major psychological problems as an adolescent and as an adult? After a complex analysis of various factors, their results indicate that children perceived as aggressive, keeping to themselves or often aggressive and keeping to themselves because of peer pressure, are liable to have problems in their adolescent years. The authors then elaborate on the difficulties experienced by each of these three groups

Propensity Score-Matched Analysis of Open Surgical and Endovascular Repair for Type B Aortic Dissection

Objective. To identify national outcomes of thoracic endovascular aortic repair (TEVAR) for type B aortic dissections (TBADs). Methods. The Nationwide Inpatient Sample database was examined from 2005 to 2008 using ICD-9 codes to identify patients with TBAD who underwent TEVAR or open surgical repair. We constructed separate propensity models for emergently and electively admitted patients and calculated mortality and complication rates for propensity score-matched cohorts of TEVAR and open repair patients. Results. In-hospital mortality was significantly higher following open repair than TEVAR (17.5% versus 10.8%, P = .045) in emergently admitted TBAD. There was no in-hospital mortality difference between open repair and TEVAR (5.6% versus 3.3%, P = .464) for elective admissions. Hospitals performing thirty or more TEVAR procedures annually had lower mortality for emergent TBAD than hospitals with fewer than thirty procedures. Conclusions. TEVAR produces better in-hospital outcomes in emergent TBAD than open repair, but further longitudinal analysis is required

Inferential Methods to Assess the Difference in the Area Under the Curve From Nested Binary Regression Models

The area under the curve (AUC) is the most common statistical approach to evaluate the discriminatory power of a set of factors in a binary regression model. A nested model framework is used to ascertain whether the AUC increases when new factors enter the model. Two statistical tests are proposed for the difference in the AUC parameters from these nested models. The asymptotic null distributions for the two test statistics are derived from the scenarios: (A) the difference in the AUC parameters is zero and the new factors are not associated with the binary outcome, (B) the difference in the AUC parameters is less than a strictly positive value. A confidence interval for the difference in AUC parameters is developed. Simulations are generated to determine the finite sample operating characteristics of the tests and a pancreatic cancer data example is used to illustrate this approach

Estimating the Empirical Lorenz Curve and Gini Coefficient in the Presence of Error

The Lorenz curve is a graphical tool that is widely used to characterize the concentration of a measure in a population, such as wealth. It is frequently the case that the measure of interest used to rank experimental units when estimating the empirical Lorenz curve, and the corresponding Gini coefficient, is subject to random error. This error can result in an incorrect ranking of experimental units which inevitably leads to a curve that exaggerates the degree of concentration (variation) in the population. We explore this bias and discuss several widely available statistical methods that have the potential to reduce or remove the bias in the empirical Lorenz curve. The properties of these methods are examined and compared in a simulation study. This work is motivated by a health outcomes application which seeks to assess the concentration of black patient visits among primary care physicians. The methods are illustrated on data from this study

SAMS Acceleration Measurements on MIR

During NASA Increment 3 (September 1996 to January 1997), about 5 gigabytes of acceleration data were collected by the Space Acceleration Measurement System (SAMS) onboard the Russian Space Station, Mir. The data were recorded on 11 optical disks and were returned to Earth on STS-81. During this time, SAMS data were collected in the Priroda module to support the following experiments: the Mir Structural Dynamics Experiment (MiSDE) and Binary Colloidal Alloy Tests (BCAT). This report points out some of the salient features of the microgravity environment to which these experiments were exposed. Also documented are mission events of interest such as the docked phase of STS-81 operations, a Progress engine burn, attitude control thruster operation, and crew exercise. Also included are a description of the Mir module orientations, and the panel notations within the modules. This report presents an overview of the SAMS acceleration measurements recorded by 10 Hz and 100 Hz sensor heads. Variations in the acceleration environment caused by unique activities such as crew exercise and life-support fans are presented. The analyses included herein complement those presented in previous mission summary reports published by the Principal Investigator Microgravity Services (PIMS) group

SAMS Acceleration Measurement on Mir From March to September 1996

During NASA Increment 2 (March to September 1996), over 15 gigabytes of acceleration data were collected by the Space Acceleration Measurement System (SAMS) onboard the Russian Space Station, Mir. The data were recorded on 55 optical disks and were returned to Earth on STS-79. During this time, SAMS data were collected in the Kristall and Kvant modules, and in the Priroda module to support the following experiments: the Queen's University Experiments in Liquid Diffusion (QUELD), the Technological Evaluation of the MIM (TEM), the Forced Flow Flame Spreading Test (FFFT), and Candle Flames in Microgravity (CFM). This report points out some of the salient features of the microgravity environment to which these experiments were exposed. Also documented are mission events of interest such as the docked phase of STS-76 operations, an extravehicular activity (EVA) to install and deploy solar panels on the Kvant module, a Progress engine burn to raise Mir's altitude, and an on-orbit SAMS calibration procedure. Also included are a description of the Mir module orientations, and the panel notations within the modules. This report presents an overview of the SAMS acceleration measurements recorded by 10 Hz and 100 Hz sensor heads. Variations in the acceleration environment caused by unique activities such as crew exercise and life-support fans are presented. The analyses included herein complement those presented in previous mission summary reports published by the Principal Investigator Microgravity Services (PIMS) group