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Biomedical subjects

J N Perry

Publications and source records attributed to J N Perry.

7 recordsLinked to original sources
PubMed2000

Fitting host-parasitoid models with CV2 > 1 using hierarchical generalized linear models.

The powerful general Pacala-Hassell host-parasitoid model for a patchy environment, which allows host density-dependent heterogeneity (HDD) to be distinguished from between-patch, host density-independent heterogeneity (HDI), is reformulated within the class of the generalized linear model (GLM) family. This improves accessibility through the provision of general software within well-known statistical systems, and allows a rich variety of models to be formulated. Covariates such as age class, host density and abiotic factors may be included easily. For the case where there is no HDI, the formulation is a simple GLM. When there is HDI in addition to HDD, the formulation is a hierarchical generalized linear model. Two forms of HDI model are considered, both with between-patch variability: one has binomial variation within patches and one has extra-binomial, overdispersed variation within patches. Examples are given demonstrating parameter estimation with standard errors, and hypothesis testing. For one example given, the extra-binomial component of the HDI heterogeneity in parasitism is itself shown to be strongly density dependent.

Animals↗
PubMed2000

Validity and utility of computer-based test interpretation.

Computers have been important to applied psychology since their introduction, and the application of computerized methods has expanded in recent decades. The application of computerized methods has broadened in both scope and depth. This article explores the most recent uses of computer-based assessment methods and examines their validity. The comparability between computer-administered tests and their pencil-and-paper counterparts is discussed. Basic decision making in psychiatric screening, personality assessment, neuropsychology, and personnel psychology is also investigated. Studies on the accuracy of computerized narrative reports in personality assessment and psychiatric screening are then summarized. Research thus far appears to indicate that computer-generated reports should be viewed as valuable adjuncts to, rather than substitutes for, clinical judgment. Additional studies are needed to support broadened computer-based test usage.

Diagnosis, Computer-Assisted↗
PubMed1994

Lipomata of the inferior vena cava: a normal variant?

Recently, focal fat collections adjacent to the intrahepatic portion of the inferior vena cava (IVC) have been described as a normal variant. We present seven similar cases, and demonstrate the computed tomographic and sonographic findings. The differential diagnosis is discussed. We believe that the origin of these masses has not yet been satisfactorily proven, and that they may arise within the IVC. They appear to be benign, but there is a risk that they may be mistaken for more sinister pathology.

Aged↗
PubMed1993

A long term follow-up of Günther vena caval filters.

Seven patients with Günther inferior vena caval filters were reviewed between 28 and 60 months following insertion of the filter. Some 71% of the filters showed some sort of structural failure, the commonest of these being limb fracture (57%). Fifty-seven per cent also showed either fracture or severe distortion of the basket. Twenty-nine per cent of the filters had suffered loss of an anchoring limb. Only one patient had any clinical sequelae, this being an IVC occlusion. This study confirms that Günther inferior vena caval filters have a structural failure rate of greater than 50%.

Equipment Failure↗
PubMed1991

A new index of aggregation for animal counts.

A new index is described that is especially appropriate for measuring the aggregation of entomological data in the form of counts per sample unit and that can make use of spatial information when it is available. Calculation of the index is based on a comparison of the effort required of individuals in a sample to achieve complete crowding with that to achieve complete randomness. The power of tests of randomness based on this index is found to be greater than those based on the index of dispersion, especially when spatial information is available.

Animals↗