BACKGROUND Reference tissue-based quantification of brain PET data does not typically include correction for signal originating from blood vessels, which is known to result in biased outcome measures. The bias extent depends on the amount of radioactivity in the blood vessels. In this study, we seek to revisit the well-established Logan plot and derive alternative formulations that provide esti...

This article presents a game theoretic model of parental care which models the feedback between patterns of care and the operational sex ratio. It is assumed here that males can be in one of two states: searching for a mate or breeding (including caring for their offspring). Females can be in one of three states: receptive (searching), non-receptive or breeding. However, these sets of states ca...

The cell density, activity, and community structure of the bacterial community in wetland sediments were monitored over a 13-month period. The study was performed at Cedar Bog, an alkaline fen. The objective was to characterize the relationship between the sediment bacterial community in groundwater upwelling zones and the physical and chemical factors which might influence the community struct...

This study investigates the functional significance of heterophylly in Ginkgo biloba, where leaves borne on short shoots are ontogenetically distinct from those on long shoots. Short shoots are compact, with minimal internodal elongation; their leaves are supplied with water through mature branches. Long shoots extend the canopy and have significant internodal elongation; their expanding leaves...

We review the evidence of how organisms and populations are currently responding to climate change through phenotypic plasticity, genotypic evolution, changes in distribution and, in some cases, local extinction. Organisms alter their gene expression and metabolism to increase the concentrations of several antistress compounds and to change their physiology, phenology, growth and reproduction i...

In functional MRI it is desirable for the blood-oxygenation level dependent (BOLD) signal to be localized to the tissue containing activated neurons rather than the veins draining that tissue. This study addresses the dependence of the specificity of the BOLD signal - the relative contribution of the BOLD signal arising from tissue compared to venous vessels - on magnetic field strength. To dat...

Living systems rely on pervasive vascular networks to enable a plurality of biological function in both soft and hard tissue. Extensive vasculature in composite structures, such as osseous tissue in bone and tracheary elements in trees, exemplify natural materials that are lightweight, high-strength, and capable of mass and energy transport. In contrast, synthetic composites possess high streng...

ENDOBIOGENY AND THE BIOLOGY OF FUNCTIONS ARE BASED ON FOUR SCIENTIFIC CONCEPTS THAT ARE KNOWN AND GENERALLY ACCEPTED: (1) human physiology is complex and multifactorial and exhibits the properties of a system; (2) the endocrine system manages metabolism, which is the basis of the continuity of life; (3) the metabolic activity managed by the endocrine system results in the output of biomarkers t...

Monoaminergic systems play a crucial role in linking behaviour and physiology. Here the physiological and behavioural effects of metal exposure in relation to monoaminergic systems were considered by exposing rainbow trout dyads, demonstrating stable dominance relationships, to cadmium or lead. Fish exposed to 4 microg l(-1) cadmium accumulated more cadmium at the gill than fish held in control...

Hyperspectral imaging systems used in plant science or agriculture often have suboptimal signal-to-noise ratio in the blue region (400-500 nm) of the electromagnetic spectrum. Typically there are two principal reasons for this effect, the low sensitivity of the imaging sensor and the low amount of light available from the illuminating source. In plant science, the blue region contains relevant ...