Smoking habits in a cohort of U.K. adolescents

Active smoking is an increasing problem amongst U.K. teenagers. The smoking habits of a cohort of 14–16-year-olds were determined and the association between regular active smoking and domestic and social factors investigated.Current smoking habits of a cohort of 2289 14–16-year-olds were assessed using a simple postal questionnaire. Data concerning potential factors associated with active smoking were collected from questionnaire completed by parents.Nine hundred and sixty-nine (44·8%) children admitted to having smoked at some time, with 562 (30·0%) having smoked in the previous 12 months. Three hundred and six (14·1%) children were regular smokers and 158 (51·6% of regular smokers, 7·3% of total cohort) smoked daily. Age, number of other children in the household, parental smoking, smoking sibling(s) and living in a single parent household were all independently associated with regular smoking.Regular smoking was a significant problem amongst this cohort of teenagers. Living with other smokers, age, household size and living with one parent all predicted a regular smoking habit

Semi-Supervised Regression and System Identification

System Identification and Machine Learning are developing mostly as independent subjects, although the underlying problem is the same: To be able to associate “outputs” with “inputs”. Particular areas in machine learning of substantial current interest are manifold learning and unsupervised and semi-supervised regression. We outline a general approach to semi-supervised regression, describe its links to Local Linear Embedding, and illustrate its use for various problems. In particular, we discuss how these techniques have a potential interest for the system identification world

National-scale analyses of habitat associations of Marsh Tit Poecile palustris and Blue Tits Cyanistes caeruleus: two species with opposing population trends in Britain

Capsule Marsh Tits were strongly associated with both the amount and species diversity of woodland understorey; Blue Tits were associated with large trees and deadwood. Aims To gather quantitative information on the habitat requirements of Marsh Tits, in comparison with those of Blue Tits, across a large number of sites in England and Wales, and secondly to evaluate the range of habitat conditions likely to encourage the presence, and increase the abundance of, each species. Methods Counts of birds were made at each of 181 woods across England and Wales, and habitat data were collected from the same locations in each woodland. Marsh Tit and Blue Tit presence and abundance were related to habitat characteristics, interspecific competition and deer impact. Results Shrub cover and species diversity were important for the presence and abundance of Marsh Tits, across their geographical range in Britain. Blue Tits were associated with large trees and deadwood. Conclusion Our results support the hypothesis that changes in woodland management, leading to canopy closure and a decline in the understorey available, could have had an impact on Marsh Tits, and may have led to the observed population decline. These same changes were also consistent with population increase in Blue Tits

Medidas corporales y concentración sérica y folicular de lípidos y glucosa en vacas Brahman fértiles y subfértiles Body measurements and serum and follicular concentrations of lipids and glucose in fertile and subfertile Brahman cows

El objetivo de este estudio fue evaluar las diferencias en las medidas corporales en vacas Brahman fértiles y subfértiles, establecer las diferencias en la concentración de colesterol, lipoproteínas y glucosa en suero y líquido folicular, y desarrollar un modelo para predecir subfertilidad en vacas Brahman a partir de las medidas corporales. Se seleccionaron vacas Brahman registradas, agrupadas en fértiles (15) y subfértiles (15) según historial reproductivo. Se tomaron muestras de suero y líquido folicular (diámetro >8 mm) para determinar colesterol, lipoproteínas, triacilgliceroles y glucosa. Las vacas subfértiles mostraron un fenotipo masculino, con medidas corporales mayores, y concentraciones de colesterol y HDL séricos y foliculares más bajas que las vacas fértiles. El colesterol y el HDL se correlacionaron positivamente entre los compartimientos en ambos grupos. La subfertilidad es más probable en vacas pesadas con hombros amplios y mayor perímetro torácico. El tamaño corporal en vacas Brahman subfértiles se relacionó con su apariencia, con cambios en los metabolitos séricos y foliculares y con las concentraciones de colesterol y HDL.<br>The objective of this study was to evaluate differences in body size among Brahman cows, grouped according to their fertility, to establish differences in concentrations of cholesterol, lipoproteins, and glucose, in serum and follicular fluid, and to develop a model to predict subfertility in Brahman cows using body measurements as predictors. Registered Brahman cows were selected and grouped in fertile (15) and subfertile (15) animals, according to their calving interval. Samples of blood serum and liquid from follicles (diameter >8 mm) were collected in order to determine cholesterol, lipoproteins, triacylglycerols, and glucose. Subfertile cows had a masculine phenotype, their body measurements were larger than those in fertile cows, and they had lower cholesterol and HDL concentrations in serum and follicular fluid. Cholesterol and HDL between compartments were positively correlated in both groups. Subfertility is more probable in heavier cows with wider shoulders, and larger thoracic perimeter. Body size in subfertile Brahman cows was related to their appearance, and to changes in serum and follicular cholesterol and HDL concentrations