Showing papers by "University of Liverpool published in 1991"

The united nations convention on the rights of the child

Abstract: States parties to the Convention are obliged to develop and undertake all actions and policies in the light of the best interests of the child. The Convention sets out these rights in 54 articles and two Optional Protocols. It spells out the basic human rights that children everywhere have: • the right to survival; • to develop to the fullest; • to protection from harmful influences, abuse and exploitation; • and to participate fully in family, cultural and social life. The four core principles of the Convention are • non-discrimination; • devotion to the best interests of the child; • the right to life, survival and development; • and respect for the views of the child.

Lumped parameter thermal model for electrical machines of TEFC design

Abstract: A lumped-parameter thermal model is described which provides both a steady-state and transient solution to the temperatures within an electrical machine of the TEFC design. The model is sufficiently complex to identify the temperatures at most locations in the machine, including the peak temperatures in the endwinding and the surface temperatures of the rotor. It is formulated out of purely dimensional information and constant thermal coefficients and is therefore easily adapted to a range of frame sizes. The thermal behaviour of the TEFC machine is accurately described by the solution of just eight linear differential equations. The model is therefore suitable for application to online temperature estimation for protection and duty-cycle evaluation. The application of the thermal model to a medium (75 kW) and two small (5.5 kW) induction motors is described in detail. The model performance is confirmed by experimental temperature data obtained from varying load tests on each of the three induction motors.

Plant-animal interactions in the marine benthos

Abstract: List of contributors Habitats and regional perspectives: S.J. Hawkins, R.G. Hartnoll, J.M. Kain, & T.A. Norton: Plant-animal interactions on hard substrata in the Northeast Atlantic R.L. Vadas & R.W. Elner: Plants-animal interactions in the Northwest Atlantic M.S. Foster: Plant animal interactions in the Northeast Pacific: the importance of grazing to seaweed evolution and assemblage structure D.M. John, J.H. Price, & G.W. Lawson: Tropical East Atlantic and islands: plant-animal interactions on tropical shores free of biotic reefs Deborah M. Brosnan: Ecology of tropical rocky shores: plant-animal interactions in tropical and temperate latitudes K. Reise: Grazing on sediment shores R.J. Orth: A perspective on plant-animal interactions in seagrasses: physical and biological determinants influencing plant and animal abundance L. Mazzella, M.C. Buia, M.C. Gambi, M. Lorenti, G.F. Russo, M.B. Scipione, & V. Zupo: Plant-animal trophic relationships in the posidonia oceanica ecosystem of the Mediterranean Sea: a review G.A. Williams & R. Seed: Interactions between macrofaunal epiphytes and their host algae N.V.C. Polunin & D.W. Klumpp: A trophodynamic model of fish production on a windward reef tract Processes and types of plant-animal interaction: Susan H. Brawley: Mesograzers B.L. Bayne & A.J.S. Hawkins: Herbivory in benthic suspension-feeding molluscs M.G. Chapman & A.J. Underwood: Foraging behaviour of marine benthic grazers M.E. Hay & W. Fenical: Chemical mediation of seaweed-herbivore interactions M.H. Horn: Herbivorous fish: feeding and digestion mechanisms B. Santelices: Digestion survival of algae: an overview A.N.C. Morse: Role of algae in the recruitment of marine invertebrate G.M. Branch, J.M. Harris, C. Parkins, R.H. Bustamente, & S. Eckhout: Algal gardening by marine grazers: a comparison of the ecological effects of territorial fish and limpets W.P. Sousa & J.H. Connell: Grazing and succession A.J. Underwood: Competition and marine plant-animal interactions R.S. Steneck: Plant-herbivore coevolution: a reappraisal from the marine realm and its fossil record T. Spencer: Bioerosion and biogeomorphology Endosymbiosis: P.S. Spencer-Davies: Endosymbiosis in marine cnidarians Summary and future view: A.J. Underwood: Summary and future prospects for plant-animal interactions Index List of Systematics Association Publications.

Reality monitoring and psychotic hallucinations.

Abstract: Hallucinating psychiatric patients, patients with delusions but without a history of hallucinations and normal controls were compared on a reality-monitoring task in which they were first required to generate answers to easy or difficult clues and to listen to low-probability or high-probability paired associates. After an interval of one week, the subjects were presented with a list in which their answers to the clues were mixed with the associates and with words not previously presented, and they were required to identify the source of each item (self-generated, presented by the experimenter or new). The psychiatric patients were generally less accurate in identifying the source of the items in comparison with the normal controls. However, hallucinators more often misattributed high cognitive effort self-generated items (answers to difficult clues) to the experimenter than either the psychiatric or the normal controls. The results are interpreted as consistent with the hypothesis that hallucinations are self-generated events misattributed to an external source.

The Croonian Lecture, 1991: Genostasis and the Limits to Evolution

Abstract: The Darwinian explanation for evolution is that it is the outcome of the interaction between genetic variation and natural selection. There is now good evidence for both the existence of genetic variation and the occurrence of natural selection, the latter potentially at high intensities. The outcome should be rapid evolutionary change; yet in practice very little change is found. Most species are very stable, and in situations where evolution is observed in one species often none is found in others despite equivalent opportunity. Evolutionary failure is commonplace. Despite the occurrence of high levels of protein polymorphism, there is good evidence that the supply of variation making a major contribution to fitness is very limited. As a result it is argued that lack of evolution in most species may be due more to lack of appropriate variability than to other causes: a condition for which the term `genostasis' is proposed. In those situations where appropriate genetic variation is available for one reason or another, evolution is found to be very rapid. There are good theoretical and practical reasons for more attention being paid to the mechanisms of supply of new variation and to those situations where evolution appears not to be taking place.

The importance of small-scale faulting in regional extension

Abstract: A RECURRING observation in many studies of extensional basins has been that the amount of extension visible on normal faults (for example, on seismic reflection profiles) is significantly less than the amount of extension indicated by crustal thickness and thermal subsidence1–5. One mechanism suggested to account for this discrepancy is small-scale faulting, with offsets too small to be resolved seismically6,7. But earthquake studies8–10 indicate that small faults are responsible for only a small fraction of the total seismic moment in an active area. Scholz and Cowie11 have recently attempted to extend this approach to the total strain at the end of a finite deformation interval by combining scaling laws describing the distributions of fault lengths and displacements. Here we present fault displacement data that directly conflict with Scholz and Cowie's conclusions, and imply that up to 40% of the extension may be missed by summing fault offsets on basin profiles. The fault population at the end of a long deformation interval may differ substantially from that responsible for the earthquake population at any one time.

Elevated P53 expression correlates with a history of heavy smoking in squamous cell carcinoma of the head and neck

Abstract: Expression of the tumour suppressor gene p53 was examined in squamous cell carcinoma of the head and neck using two p53 antibodies, PAb 421 and PAb 1801. Elevated p53 expression was found in 67% of the 73 patients investigated. P53 expression was not found to correlate with whether the patient had been previously treated or not, nor any of the clinico-pathological parameters. However a correlation was found between the patients smoking history and positive p53 staining. Six out of seven non-smokers did not express p53 whereas 29 of 37 heavy smokers were found to have elevated p53 expression (P less than 0.005). Also, of a group of ten patients who had given up smoking more than 5 years ago, nine had elevated expression. Epidemiological studies have shown a correlation between heavy smoking and head and neck cancer. The present study indicate a genetic link for this correlation.

Excitatory amino acid receptors coupled to the nitric oxide/cyclic GMP pathway in rat cerebellum during development.

Abstract: The coupling of excitatory amino acid receptors to the formation of nitric oxide (NO) from arginine during the postnatal development of rat cerebellum was assayed in slice preparations by measuring cyclic GMP accumulation. In the immature tissue, N-methyl-D-aspartate (NMDA) and glutamate were highly efficacious agonists, whereas alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) and quisqualate evoked only small responses. The effect of glutamate at all concentrations tested (up to 10 mM) was abolished by the NMDA antagonist, (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801). In adult slices, AMPA and quisqualate were much more effective and their effects were inhibited by 6-cyano-7-nitroquinoxaline-2,3-dione, an antagonist for ionotropic non-NMDA receptors, whereas the apparent efficacy of NMDA was greatly reduced. The major changes took place between 8 and 14 days postnatum and, in the case of NMDA, part of the loss of sensitivity appeared to reflect a decline in the ambient levels of glycine with age. Moreover, a component of the response to glutamate in the adult was resistant to MK-801. Cyclic GMP accumulations induced by NMDA and non-NMDA agonists alike were Ca(2+)-dependent and could be antagonized by competitive NO synthase inhibitors in an arginine-sensitive manner, indicating that they are all mediated by NO formation. With one of the inhibitors, L-NG-nitroarginine, a highly potent component (IC50 = 6 nM) evident in slices from rats of up to 8 days old was lost during maturation, indicating that there may be a NO synthase isoform which is prominent only in the immature tissue. Cyclic GMP levels in adult slices under "basal" conditions were reduced markedly by blocking NMDA receptors, by inhibiting action potentials with tetrodotoxin, or by NO synthase inhibition, suggesting that the endogenous transmitter released during spontaneous synaptic activity acts mainly through NMDA receptors to trigger NO formation.

Computer simulation of the structure and mobility of twinning disclocations in H.C.P. Metals

Abstract: The properties of twinning dislocations in [10 1 1}, {11 1 2}, {11 2 2} twin boundaries in hexagonal-close-packed metals have been investigated by atomic-scale computer simulation. Care has been exercised (by use of the concept of bicrystal structure maps) to ensure that all possible stable interface structures have been modelled and the work extends the research reported earlier by us [6] in several ways. First, we have now treated the important case of the {10 1 1} twin Second, the dependence of dislocation energy on the atomic structure of the core has been investigated. Third, the mobility of these interfacial dislocations has been examined by computing the critical resolved shear strain for glide. It has been found that the twinning dislocations corresponding to the {10 1 2} and {11 2 1} twins observed in practice are highly glissile, wheras those for the {10 1 1} and {11 2 2} modes are not. These effects are deduced to be related to the atomic structure of the core (and, in particular, to its width rather than height), and are found to be consistent with the nature of deformation twinning reported for the h.c.p. metals. For {10 1 1} twinning, however, the dislocation of lowest energy and highest mobility does not correspond to the mode observed in practice, implying that twin nucleation may possibly be a controlling factor in that case.

Impairment of the visuo-spatial sketch pad.

Abstract: A case study is presented of a female patient, ELD, who has difficulty in the immediate recall of short sequences of visuo-spatial material following a right-hemisphere aneurysm. Despite poor performance on tasks such as the Brooks Matrix and the Corsi Blocks, ELD is good at the immediate serial recall of letters even when presentation modality is visual and shows effects of phonological similarity and articulatory suppression. This pattern of performance represents a double dissociation from that which has been observed with the short-term memory patient PV (Vallar & Baddeley, 1984), who is extremely poor at serial recall of verbal material but shows no visual memory impairment. It is argued that ELD has an impairment to the visuo-spatial component of working memory (Baddeley, 1986) in the absence of any phonological loop deficit. Further investigation reveals that ELD performs poorly on mental rotation tasks and finds it difficult to use imagery mnemonics, but has no difficulty in retrieving visuo-spati...

241Am dating of lake sediments

Abstract: 241Am derived from decay of fallout 241Pu is now frequently detected in analyses of lake sediments by low-background gamma assay, and offers an alternative to weapons test 137Cs in dating recent sediments at those sites where the 137Cs record has been degraded by post-depositional mobility or obliterated by Chernobyl fallout Calculations of the in-growth of 241Am from 241Pu indicate a nominal distribution broadly similar to that of 137Cs, with the maximum 241Am activity occuring in fallout dating from 1963 Results from a number of sites suggest that 241Am is significantly less mobile in lake sediments than 137Cs, and that its distribution in cores reflects more closely the fallout record Since further decay of existing weapons debris will increase 241Am concentrations by about 24% over the next 40 years, 241Am is likely to play an increasingly important role in assessing the validity of 210Pb dates at sites with varying sediment accumulation rates

The recovery of metals from electronic scrap

Abstract: Most of the published literature on the recycling of scrapped electronic devices is listed in chronological order in Table I. In the 1970s and early to mid-1980s, the predominant method of recycling was blast furnace smelting in conjunction with secondary copper or lead smelters. Since the mid-1980s, the trend has shifted toward the hydrometallurgical processing of scrap. The emphasis has always been on the recovery of precious metals, namely gold, silver, platinum and palladium, from electronic scrap for their obvious economic values. In recent years, greater importance has been placed on the recovery of all metals, including low-concentration metals such as cadmium, because of increasingly strict environmental controls. The electronic scrap recycling program of the 1990s will ha ve to meet many objectives—efficient recovery of all metals, strict effluent and emission controls, the use of nontoxic reagents, maximum recycling of chemical reagents, and minimum energy requirements—in an economical and environmentally safe manner.

The occurrence of fibre-type grouping in healthy human muscle: a quantitative study of cross-sections of whole vastus lateralis from men between 15 and 83 years.

Abstract: Methods that objectively assess the muscle fibre-type arrangement may improve the detection of fibre-type grouping, a diagnostic sign of a denervation and reinnervation process. To distinguish between a diseased and a normal muscle, there is a need for quantitative data on the fibre-type arrangement in healthy human muscles at different ages. In this study, cross-sections were prepared of whole autopsied vastus lateralis muscle from 24 previously physically healthy men, aged 15 to 83 years. The arrangements of type 1 and type 2 fibres were assessed in terms of the number of enclosed fibres in individual fascicles throughout each muscle. Recent improvements to the enclosed fibre method were used to define measures of randomness which facilitated the combination of several sample areas and the quantification of the fibre-type arrangements. Segregation was typical for young muscles, randomness was most common between 30 and 50 years of age, while some fibre-type grouping was considered “normal” in old muscles. The arrangements of type 1 and type 2 fibres were quantitatively similar, irrespective of the age of the individual. The results imply that the fibre population changes considerably during a lifetime, and that it undergoes a continuous denervation and reinnervation process with normal ageing. Because of its importance, age should be accommodated in the analysis of a muscle sample, irrespective of the statistical model and method used.

Growth mechanisms and growth kinetics of filamentous microorganisms.

Abstract: Filamentous microorganisms are of major biotechnological importance, being responsible for production of the majority of secondary metabolites, particularly antibiotics. Two main groups are involve...