RESUMEN
Generalised linear models, with "log" link and either Poisson or negative binomial errors, are commonly used for relating accident rates to explanatory variables. This paper adds to the toolkit for such models. It describes how confidence intervals (for example, for the true accident rate at given flows) and prediction intervals (for example, for the number of accidents at a new site with given flows) can be produced using spreadsheet technology.
Asunto(s)
Prevención de Accidentes/estadística & datos numéricos , Accidentes de Tránsito/estadística & datos numéricos , Modelos Lineales , Accidentes de Tránsito/prevención & control , Distribución Binomial , Intervalos de Confianza , Predicción , Humanos , Distribución de PoissonRESUMEN
This paper has two aims. The primary aim is to provide a practical resolution of the low mean value' problem, a barrier to goodness of fit testing for the commonly used generalised linear accident model. A secondary aim of the paper is to describe the underlying mechanism of these models, so making them fully accessible to the transport modeller.
Asunto(s)
Accidentes de Tránsito/prevención & control , Accidentes de Tránsito/estadística & datos numéricos , Humanos , Modelos Lineales , Distribución de PoissonRESUMEN
Methylazoxymethanol acetate (MAM) is a mitotic inhibitor that has been used to selectively destroy neuroblasts at specific times during gestation. The administration of MAM results in a dose-dependent microencephaly. Following MAM treatment at 15 days of gestation, we have noted an increase in the level of SS immunoreactivity in the neocortex, as determined by radioimmunoassay. Northern blot analysis for preproSS mRNA revealed an increase in MAM-treated cortex. The cellular distribution of SS has been determined using in situ hybridization and immunocytochemistry. There was a 30% increase in the density of SS-immunoreactive neurons in the cortex of the MAM-treated animals. These data suggest that SS neurons in the cortex are spared following MAM treatment at GD 15.
Asunto(s)
Encefalopatías/metabolismo , Encéfalo/metabolismo , Acetato de Metilazoximetanol/farmacología , ARN Mensajero/metabolismo , Somatostatina/biosíntesis , Animales , Encéfalo/efectos de los fármacos , Encéfalo/patología , Encefalopatías/inducido químicamente , Encefalopatías/patología , Corteza Cerebral/metabolismo , Corteza Cerebral/patología , Cuerpo Estriado/metabolismo , Cuerpo Estriado/patología , Relación Dosis-Respuesta a Droga , Femenino , Hipocampo/metabolismo , Hipocampo/patología , Hibridación in Situ , Masculino , Intercambio Materno-Fetal , Embarazo , Ratas , Ratas Sprague-Dawley , Somatostatina/análisis , Somatostatina/genéticaRESUMEN
An automated method for the determination of submicrogram amounts of selenium in vegetation is described. A weighed sample of vegetation is digested with a 4:1 nitric-perchloric acid mixture, and made up to a known volume. The digested sample is placed in a Technicon sampler and reacted with sodium borohydride solution. The selenium converted into the gaseous hydride is swept by an argon stream into a gas-liquid separator. The mixed gas stream is passed through a heated quartz cell, positioned in the light-path of an atomic-absorption spectrophotometer. The absorption by the atomized selenium is recorded. The method is capable of analysing 50 samples a day by the use of a calibration curve or 25 a day by the standard addition technique. A relative standard deviation of better than 10% and a detection limit of 0.025 microg/g were obtained.