Showing papers by "University of Liverpool published in 1975"

Statistical Analysis of Non-Lattice Data

Abstract: In rather formal terms, the situation with which this paper is concerned may be described as follows. We are given a fixed system of n sites, labelled by the first n positive integers, and an associated vector x of observations, Xi, . . ., Xn, which, in turn, is presumed to be a realization of a vector X of (dependent) random variables, Xi, . . ., X.. In practice, the sites may represent points or regions in space and the random variables may be either continuous or discrete. The main statistical objectives are the following: firstly, to provide a means of using the available concomitant information, particularly the configuration of the sites, to attach a plausible probability distribution to the random vector X; secondly, to estimate any unknown parameters in the distribution from the realization x; thirdly, where possible, to quantify the extent of disagreement between hypothesis and observation.

On the longitudinal dispersion of passive contaminant in oscillatory flows in tubes

Abstract: The paper examines how a passive contaminant disperses along the axis of a tube in which the flow is driven by a longitudinal pressure gradient varying harmonically with time. This problem is of intrinsic interest and is relevant to some important practical problems. Two examples are dispersion in estuaries and in the blood stream. By means both of statistical arguments and an analysis like that used by Taylor (1953) in the case of a steady pressure gradient it is shown that eventually the mean distribution of concentration satisfies a diffusion equation (and is therefore a Gaussian function of distance along the axis) with an effective longitudinal diffusion coefficient K(t) which is a harmonic function of time with a period equal to one half of that of the imposed pressure gradient. Contrary to the supposition made in most previous work on this problem it is shown by examining some special cases that the harmonic terms in K(t) may have a noticeable effect on the dispersion of the contaminant and in particular on the rate at which it is spreading axially. The size of the effect depends on both the frequency and the Schmidt number and is particularly large at low frequencies. The paper concludes with an analysis of a model of dispersion in estuaries which has been used frequently and it is concluded that here too oscillatory effects may often be noticeable.

The Orowan mechanism in anisotropic crystals

Abstract: The static equilibrium configurations of a dislocation bypassing a periodic row of impenetrable circular obstacles were obtained for various crystals by means of a self-stress method wherein the elastic anisotropy of the crystal and the dislocation self-interaction could be taken into account. A correlation was developed from the results which related the Orowan stress values to the obstacle size and spacing. This correlation demands two parameters to account for the anisotropy, and these appear as a suitably defined anisotropic shear modulus and Poisson's ratio. The self-interactions are taken into account by a single logarithmic parameter which is the harmonic mean of the obstacle size and spacing, and is independent of anisotropy. The shapes of the bowing dislocation loops are strongly influenced by the anisotropy and interactions. The combined effects on shape can bo simply described in the line-tension framework, using the de Wit—Koehler solutions. In particular, the swept areas and overall ...

On the estimation and testing of spatial interaction in Gaussian lattice processes

Abstract: SUMMARY Maximum likelihood estimation for rectangular lattice autonormal schemes is discussed. Explicit results for the first-order isotropic scheme are given and compared with those obtained using a simple coding technique. The efficiency of the coding technique in testing for randomness on various types of lattice is assessed.

Competition between metal tolerant and normal plant populations; a field experiment on normal soil.

Abstract: In broad terms, the fitness of an individual may be considered as being a measure of its capacity to leave viable offspring. Ability to leave viable offspring will be influenced by genetic factors, environmental factors, and the interaction of these two. Amongst environmental factors of importance will be the effects of neighbors, which may be such as to enhance fitness, or to reduce it through competition for nutrients, light, water or space. In plants, genetically determined differences in competitive ability, have been shown almost exclusively in crops, oats and barley (de Wit, 1960), rice (Jennings and de Jesus, 1968), in barley and wheat (Adams and Allard, 1969), in soy beans (Schutz and Brim, 1967) and flax and linseed (Khan et al., 1974), whilst the benefits in terms of yield of herbage of the grass/ clover mixture in agriculture are widely documented (Davies, 1960; Cowling et al., 1964). The data of Harlan and Martini (1938) illustrate the influence of genotype environment interaction in changing the dominant type in competing mixtures of barley varieties. These genetically determined differences in competitive abilities must constitute a major factor in the relative fitness of individuals under many differing environmental conditions, and as such they have long been considered as playing a significant role in natural selection. The extensive studies of the evolution of heavy metal tolerance in plants (summarised by Antonovics et al., 1971) have

Hierarchical Aggregation Procedures for Interaction Data

Abstract: Hierarchical aggregation procedures for interaction data are considered in relation to the design of spatial systems for operational versions of interaction models. Two types of application are examined, in general terms and with reference to real situations. These deal with cases such as the delimitation of subsystems for hierarchical models where the objective is to maximise the proportion of intrazonal interaction, and cases such as the definition of internal zoning systems where an objective is to minimise the proportion of intrazonal interaction. The application of the intramax procedure is illustrated with reference to the identification of migration subsystems within Greater London and the definition of labour-market areas within Merseyside, while the application of the intramin procedure is demonstrated with respect to the design of an internal zoning system for a work-trip model of the Wirral subsystem within Merseyside.

Algorithm 495: Solution of an Overdetermined System of Linear Equations in the Chebychev Norm [F4]

Abstract: Received 3 June 1974 and 28 January 1975. Copyright (~) 1975, Association for Computing Machinery, Inc. General permission to republish, but not for profit, all or part of this material is granted provided that ACM's copyright notice is given and that reference is made to the publication, to its date of issue, and to the fact that reprinting privileges were granted by permission of the Association for Computing Machinery. Authors' addresses: I. Barrodale, Department of Mathematics, Umversity of Victoria, Victoria, B.C., Canada; C. Phillips, Department of Computational and Statistical Science, Umversity of Liverpool, Liverpool, England.

Synergistic effects of salinity, temperature and heavy metals on mortality and osmoregulation in marine and estuarine isopods (Crustacea)

Abstract: The effects of cadmium (3CdSO4·8H2O), zinc (ZnSO4·7H2O) and lead [Pb (NO3)2] on mortality, and cadmium, zinc and mercury (HgCl2) on osmoregulation, have been recorded for marine and estuarine species of isopods (Crustacea). The marine species studied were Idotea baltica, I. neglecta, I. emarginata and Eurydice pulchra, which were adapted to 100, 80, 60 and 40% sea water (SW) (100% SW э 34‰ S). The estuarine species used were Jaera albifrons sensu stricto and J. nordmanni, which were adapted to 100, 50, 10 and 1% SW. Both groups of isopods have low mortalities in 100% SW with 10 and 20 ppm of cadmium, zinc and lead, but a decrease in salinity caused an increase in the toxicities of these metals and reduced the LT50 values (time, in hours, to 50% mortality). Mortalities at 10°C were generally higher than those recorded at 5°C. Cadmium had no significant effect on the osmoregulation of I. baltica and I. emarginata in 100 and 80% SW at 5°C, but this metal significantly lowered the blood osmotic concentration of I. neglecta in 80% SW. Zinc did not alter the haemolymph osmotic concentration of I. neglecta in 100 and 80% SW, but significantly lowered the blood osmotic concentration of I. baltica in 100% SW. Cadmium, zinc and mercury also significantly altered the osmoregulatory ability of J. albifrons in dilute saline.

On trapped waves over a continental shelf

Abstract: Any straight continental shelf of monotonic depth profile is shown to have as its entire complement of barotropic trapped modes (i) an infinite discrete set of ‘continental-shelf waves’, (ii) a single ‘Kelvin wave’, and (iii) an infinite discrete set of ‘edge waves’. The decomposition of energy density and fluxes into modal constituents is discussed.

Pimozide in the treatment of monosymptomatic hypochondriacal psychosis.

Abstract: An account is given of six cases treated with pimozide. Four of there cases fall into the diagnostic category of monosymptomatic hypochondriacal psychosis, a group with a traditionally poor prognosis. Three out of the four have responded favourably to pimozide, while the fourth showed a partial improvement. A fifth case also showed a marked degree of improvement despite a possibility of early cerebral arteriopathy. The one case which showed no improvement was suspected all along of having a personality disorder rather than a psychotic illnes, and this was subsequently confirmed. It is suggested that pimozide: a) may be an effective treatment for monosymptomatic hypochondriacal psychoses whatever their aetiology; and b) may differentiate rapidly between cases of mono-symptomatic hypochondriacal psychoses and dysmorphophobias due to neurotically determined factors.

Male Discrimination and Investment in Asellus Aquaticus (L.) and a. Meridianus Racovitsza (Crustacea : Isopoda)

Abstract: The following observations are presented :-1) A description of male: female interaction in A. aquaticus and A.meridianus. This indicates the presence of a male discrimination mechanism in that large females are selected for the passive phase before their smaller counterparts. 2) Passive phase durations in allopatric and sympatric populations of A. aquaticus and A. meridianus. No significant difference was found between species; however two populations of A. meridianus differed significantly from each other (<0.05P). The duration of passive phase is shown to be substantial (means varying from 5.3-11.2 days). Intermittent pairing was shown to occur, in particular with small females. 3) The relationships between the parameters a) female size: day the passive phase commenced for each couple and b) female size: day each female became ovigerous. That is large females were found paired and became ovigerous before their smaller counterparts. Both relationships are shown to be significant (at 0.05 level of probability or less) in four of the five populations investigated. It is suggested these observations may be interpreted in the following way: Males of both species are selecting for passive phase association those females exhibiting a cue which correlates with imminent oviposition and large brood size. This cue may be female size or another characteristic which is correlated to size. This behaviour pattern yields an increase in offspring number to those males exhibiting it.

The Grapsidae and Ocypodidae (Decapoda: Brachyura) of Tanzania

Abstract: Twenty-nine species of the Grapsidae and 15 species of the Ocypodidae were collected from the littoral zone in the area around Dar es Salaam. Nine species of Grapsidae and three of Ocypodidae were new records for the East African area, bringing the total of recorded species for the region to 35 and 26 respectively. The distribution of these crabs indicates a very limited endemism in the western Indian Ocean, with the majority of species forming an attenuated extension of the abundant Indo/West Pacific brachyuran fauna. The habitat preference of each species is described. Within each subfamily there is a relative uniformity in general habitat preference, mode of life and manner of feeding. The species of each subfamily are then separated by substrate choice and preferred level on the shore. The greatest numbers of species occur in the most diverse habitats—the creek mangrove, the coastal mangrove and the reef flat.

The pathology of the lung in paraquat poisoning

Abstract: There have been numerous fatalities following accidental or deliberate ingestion of the weedkiller paraquat and these have received great attention both in the popular and scientific press. Most fatalities have occurred following the oral ingestion of Grammoxone, the concentrated form of the substance. Although this is not supposed to be readily available to the general public, people $ illicitly obtain samples of the weedkiller which they store at home in lemonade or beer bottles. In this way there is a great danger that the paraquat will be accidentally drunk by children or even unwary adults. Many fatalities have resulted from this careless disregard for precautions since only one v mouthful of Grammoxone appears to be all that is required for a fatal outcome. The disease is confined almost exclusively to the lungs and consists essentially of a fulminating

Recall of medical advice: comprehensibility and specificity.

Abstract: Two laboratory experiments are described in which volunteer subjects read advice on how to develop self-control over eating behaviour Formulating the communications in terms of specific instructions rather than general rules and the use of simple language as determined by a readability formula led to increased recall of the advice These findings were confirmed in a naturalistic setting in which the same material was presented orally to patients receiving treatment for obesity The results of these investigations are believed to have implications for improving communications between doctors and their patients and possibly for increasing the degree to which patients comply with medical recommendations

The Stratigraphical Significance of Trace Fossils

Abstract: Trace fossils have many uses in stratigraphy. Short-ranging forms can date otherwise unfossiliferous successions, as exemplified here by lower Paleozoic successions in Europe and North America. Trace fossils, including trilobite tracks, also commonly extend beneath the lowest fossiliferous Phanerozoic horizons. This distribution suggests that (1) trilobites may have evolved rapidly at this time fwm soft-bodied ancestors and (2) trace fossils should be considered in defining a base to the Cambrian system.

Absence of crossing-over in female butterflies (Heliconius).

Abstract: Absence of recombination between linked markers in female Heliconius is suggested by coupling backcross broods in H erato, by a repulsion F2 in H melpomene, and by other crosses with this species No recombinants have been found in the offspring of doubly heterozygous females in either species This supports the contention that the absence of chiasmata at oogenesis in these butterflies prevents genetic crossing-over Chiasmata are absent in all the female Lepidoptera examined by Suomalainen and others, but Ephestia seems to show the absence of chiasmata but the presence of genetic recombination in the female, and therefore would repay further study

Studies on the ecology of actinomycetes in soil—VIII: Distribution and characteristics of acidophilic actinomycetes

Abstract: Acidophilic actinomycetes, growing between pH 3.5 and 6.5, were isolated from 17 natural soils and mine wastes. Most isolates were Streptomyces spp. and selected ones were compared with some established neutrophilic species by assessment of overall similarity. Acidophilic and neutrophilic strains clustered separately, differing in a number of cultural and physiological characters, in addition to pH requirements. The possible importance of acidophilic actinomycetes in soil is discussed.

The crystallization and interfacial bond strength of nylon 6 at carbon and glass fibre surfaces

Abstract: The nucleation and crystallization of nylon at the interface in glass-fibre and carbon-fibre reinforced nylon 6 composites has been investigated by electron microscope studies of sectioned and etched bulk specimens and solution cast and melt crystallized thin films. The fracture energies of the composites were obtained from tensile strength tests and the interfacial bond strengths were calculated from fibre pullout measurements. The fibres are shown to nucleate a columnar structure at the interface with marked differences between the structures nucleated by glass fibres and by carbon fibres and also between that nucleated by type I and type II carbon fibres. The structure around glass fibres was non-uniform and influenced to some extent by the presence of the size coating on the fibre surface. In the carbon-fibre composites the columnar structure was due primarily to physical matching of the graphite crystallites. Surface treatment of the carbon fibres to improve chemical bonding is shown to have a significant effect on bond strength which cannot be explained in terms of the columnar structure at the fibre surface. The treated fibres gave rise to only small amounts of fibre pull-out and low fracture energies whereas the untreated fibres showed extensive pull-out which was reflected in high fracture energies.