Keele University

About: Keele University is a education organization based out in Newcastle-under-Lyme, United Kingdom. It is known for research contribution in the topics: Population & Stars. The organization has 11318 authors who have published 26323 publications receiving 894671 citations. The organization is also known as: Keele University.

Do grasses fight back? The case for antiherbivore defences

Abstract: In the past, discussion about grass-grazer interactions has tended to centre on whether they represent some sort of mutualism. However, intense grazing pressure is more likely to have selected for the presence of various antiherbivore defences in grasses. Many grasses contain silica, which functions in some cases as a physical defence. Others contain various secondary compounds which have negative effects on both invertebrate and vertebrate herbivores. Much recent evidence suggests that plants with higher levels of these defences deter herbivores more effectively than plants without them.

Cost effectiveness analysis of screening for sight threatening diabetic eye disease

Abstract: Objective: To measure the cost effectiveness of systematic photographic screening for sight threatening diabetic eye disease compared with existing practice. Design: Cost effectiveness analysis Setting: Liverpool. Subjects: A target population of 5000 diabetic patients invited for screening. Main outcome measures: Cost effectiveness (cost per true positive) of systematic and opportunistic programmes; incremental cost effectiveness of replacing opportunistic with systematic screening. Results: Baseline prevalence of sight threatening eye disease was 14.1%. The cost effectiveness of the systematic programme was £209 (sensitivity 89%, specificity 86%, compliance 80%, annual cost £104 996) and of the opportunistic programme was £289 (combined sensitivity 63%, specificity 92%, compliance 78%, annual cost £99 981). The incremental cost effectiveness of completely replacing the opportunistic programme was £32. Absolute values of cost effectiveness were highly sensitive to varying prevalence, sensitivity and specificity, compliance, and programme size. Conclusion: Replacing existing programmes with systematic screening for diabetic eye disease is justified.

Tensile properties of the annulus fibrosus II. Ultimate tensile strength and fatigue life.

Abstract: Part I of this study showed that collagen fibres do need not need to be continuous to reinforce the annulus fibrosus, and that 15-mm-wide samples of annulus retain about 44% of their in situ stiffness and strength when stretched vertically. Part II investigated the ultimate tensile strength (UTS) and fatigue life of such samples. Vertical slices, 5 mm thick and 30 mm wide, were cut from the anterior and posterior margins of the annulus and adjacent vertebral bodies. Each slice was divided sagittally to obtain a matched pair of specimens. The bony ends of each specimen were secured in a materials testing machine so that the annulus could be stretched vertically, as occurs during bending movements of the spine in life. One of each pair of specimens was stretched to failure to obtain its UTS; the other was cyclically loaded at some fraction of the UTS until failure occurred. Tensile failure started with the hyaline cartilage end-plate being stripped off the underlying bone and ended with the most peripheral annular fibres pulling out of the matrix. The estimated in situ strength in the vertical direction was 3.9 MPa for the anterior annulus and 8.6 MPa for the posterior annulus. Fatigue failure could occur in less than 10000 cycles if the tensile force exceeded 45% of the UTS. The results explain why radial fissures often fail to penetrate the peripheral annulus. When compared with in vivo measurements of spinal loading, they suggest that repetitive forward bending movements could cause fatigue failure of the posterior annulus.