Showing papers by "University of Liverpool published in 1970"

Sperm competition and its evolutionary consequences in the insects

Abstract: by M. Simpson in Bee W l d 34, 14).

Surgery on compact manifolds

Abstract: Preliminaries: Note on conventions Basic homotopy notions Surgery below the middle dimension Appendix: Applications Simple Poincare complexes The main theorem: Statement of results An important special case The even-dimensional case The odd-dimensional case The bounded odd-dimensional case The bounded even-dimensional case Completion of the proof Patterns of application: Manifold structures on Poincare complexes Applications to submanifolds Submanifolds: Other techniques Separating submanifolds Two-sided submanifolds One-sided submanifolds Calculations and applications: Calculations: Surgery obstruction groups Calculations: The surgery obstructions Applications: Free actions on spheres General remarks An extension of the Atiyah-Singer $G$-signature theorem Free actions of $S^1$ Fake projective spaces (real) Fake lens spaces Applications: Free uniform actions on euclidean space Fake tori Polycyclic groups Applications to 4-manifolds Postscript: Further ideas and suggestions: Recent work Function space methods Topological manifolds Poincare embeddings Homotopy and simple homotopy Further calculations Sullivan's results Reformulations of the algebra Rational surgery References Index.

A simple study of awareness and dreaming during anaesthesia

Abstract: SUMMARY An investigation is described into the problems of recall and dreaming under light anaesthesia with nitrous oxide, muscle relaxation being provided by tubocurarine, and the anaesthetic technique being, as far as possible, standardized. Tape-recorded music of two types was used to test the patient's ability to hear and, in addition, the nature and quality of dreams was investigated. There was no evidence that patients were able to hear the tape-recordings and there was no evidence of "awareness" during the operative procedure. Dreaming occurred in 44 per cent of the patients and details of the dreams were recalled in some two-thirds of these. Hypocapnia did not protect against dreaming. Patients who showed marked movement during the operative procedure were more liable to dream than those who did not; the significance of this movement is discussed. In this (unpremedicated) group of patients nearly half described waiting for surgery as the most unpleasant feature of their surgical experience, and postoperative pain was the major complaint in a further 20 per cent. The third commonest of the major complaints was related to requests to lift the head, etc., when unable to do so in the time immediately after operation, and this finding would seem to have some minor practical significance. Unpleasant dreams were the fourth commonest major complaint.

Evolution in closely adjacent plant populations VIII. Clinal patterns at a mine boundary

Abstract: SEVERAL previous papers in this series have been concerned with the evolution of differences between tolerant and non-tolerant populations of grasses growing over the boundaries of mine tip and pasture soils (Jam and Bradshaw, 1966, McNeilly and Antonovics, 1968, Antonovics, 1968a). Metal tolerant plants differ both physiologically and morphologically from normal plants in several features other than tolerance. Differences in calcium and phosphate response are recorded by Jowett (1959) and McNeilly (1966); Turner (1967) has shown differences in sulphur response; and Schwanitz and Hahn (1 954a, 1 954b) showed from a study of a range of plant species grown under standard conditions that in general tolerant plants had smaller flowers, smaller leaves and thinner stems. This was confirmed for Silene inflata by Broker (1963) who concluded from segregating progenies that dwarfness was not linked to tolerance and had probably been selected independently. Similarly, morphological differences have been recorded in the grass Agrostis tenuis on lead mines (Bradshaw, 1959; Jowett, 1964) and copper mines (McNeiIly, 1966). The morphological characters of plants of the grass Anthoxant hum odoratum L. taken from sites along a transect across a mine/pasture boundary were investigated with three main points in view.

Long Range Coherence and the Action of Enzymes

Abstract: SOME time ago it was proposed that the energy produced in biological activities is partly stored in various materials through excitation of coherent electrical vibrations (polarization waves). If strong enough, such excitations can be stabilized through non-linear effects leading to various types of deformations1,2. R. Ferreira (personal communication) has suggested that such considerations might be of importance for an understanding of the action of enzymes. In fact the properties of a model which I have considered recently (unpublished) seems to support this idea.

Stimulus frequency in the detection of neuromuscular block in humans

Abstract: SUMMARY Study of the literature on the physiology of neuromuscular transmission suggested two new methods of assessing the degree of neuromuscular block in the human subject. These were, first, a comparison of the height of the recorded twitch tensions developed in response to repeated single stimuli applied at differing frequencies and, second, examination of the extent of reduction in amplitude of twitch tensions developed in response to a short train of four stimuli. In assessing the first method the use of three frequencies of stimulation was tried (i.e., 0.1 Hz (c.p.s.), 0.3 Hz and 1.0 Hz). It was found that as the frequency of stimulation was increased there was reduction in the amplitude of the recorded twitch response in curarized subjects, and that this reduction appeared to depend on the degree of curarization. In assessing the second method a short train of four stimuli at 2 Hz was used, and it was found that there was a progressive fade of successive recorded mechanical twitch responses in curarized subjects which again appeared to depend on the degree of curarization. It is suggested that the amplitude of the twitch response at a higher frequency expressed as a percentage of that at the slower rate, and the last response of the train of four expressed as a percentage of the first may be useful in measuring degree of neuromuscular block in man.

The approach to normality of the concentration distribution of a solute in a solvent flowing along a straight pipe

Abstract: Taylor (1953, 1954a) showed that, when a cloud of solute is injected into a pipe through which a solvent is flowing, it spreads out, so that the distribution of concentration C is eventually a Gaussian function of distance along the pipe axis. This paper is concerned with the approach to this final form. An asymptotic series is derived for the distribution of concentration based on the assumption that the diffusion of solute obeys Fick's law. The first term is the Gaussian function, and succeeding terms describe the asymmetries and other deviations from normality observed in practice. The theory is applied to Poiseuille flow in a pipe of radius a and it is concluded that three terms of the series describe C satisfactorily if Dt/a2 > 0·2 (where D is the coefficient of molecular diffusion), and that the initial distribution of C has little effect on the approach to normality in most cases of practical importance. The predictions of the theory are compared with numerical work by Sayre (1968) for a simple model of turbulent open channel flow and show excellent agreement. The final section of the paper presents a second series derived from the first which involves only quantities which can be determined directly by integration from the observed values of C without knowledge of the velocity distribution or diffusivity. The latter series can be derived independently of the rest of the paper provided the cumulants of C tend to zero fast enough as t → ∞, and it is suggested, therefore, that the latter series may be valid in flows for which Fick's law does not hold.

Permanent Aspects of the Earth's Non‐dipole Magnetic Field over Upper Tertiary Times

Abstract: Summary Investigation of collected palaeomagnetic results from continental igneous rocks and from oceanic sediment+ores, shows a persistent off-centre displacement of the effective dipole source of the main field over Quaternary and Recent times (about the past two million years). This dipole displacement is 191 f38 km northward along the rotational axis. Further evidence suggests a similar enduring displacement during all of Upper Tertiary time. The effect of this result on palaeomagnetic interpretations is discussed. The evidence also suggests that we might search for significant differences between the time-average normal and reversed field configurations, and for other internal manifestations of the north-south asymmetry. A consistently world-wide eastward declination of 3.3 k 1.0" has been found for the time-average Upper Tertiary and later field, but no satisfactory explanation has been proposed.

Studies on the ecology of actinomycetes in soil: I. The occurrence and distribution of actinomycetes in a pine forest soil

Abstract: An investigation was carried out into the quantitative and qualitative nature of an actinomycete population in the mineral horizons of a pine forest soil. Actinomycetes were isolated using a starch-casein plus antibiotics medium which was shown to be highly selective for these microorganisms. An attempt was made to relate the distribution of the population as a whole and of individual isolates to various environmental factors. Depth, pH and moisture levels of the soil appeared to exert varying influences on different isolates. Horizons could not be sharply defined by their actinomycete flora. The spatial heterogeneity of soil samples obscured any seasonal variation in the population which might have occurred.

Braid groups and the group of homeomorphisms of a surface

Abstract: Braid groups on the plane were denned by Artin(1) in 1925. More recently Fox(8) defined braid groups on arbitrary topological spaces, the situation being particularly interesting if the space is a 2-manifold. Presentations of the braid groups on R2, S2 and P2 can be found in (2), (6) and (13) respectively, and some general results on braid groups of compact 2-manifolds can be found in (7). In section 1 of this paper, we give finite presentations for the braid groups on all closed 2-manifolds except S2 and P2.

Unsteady flow of an elastico-viscous liquid

Abstract: Consideration is given to the reasons why theColeman- andNoll second order fluids are unsuitable for use in the solution of unsteady flow problems for elasticoviscous liquids, especially whenLaplace transforms are used. A number of unsteady flow problems are then solved using a constitutive equation of the „integral” type. The presence of elasticity in the liquid is shown to have quite a dramatic effect on the velocity profiles.

The Reproductive Behaviour and the Nature of Sexual Selection in Scatophaga Stercoraria L. (Diptera : Scatophagidae)

Abstract: Females in all stages of their reproductive cycle around dung are equally attractive in eliciting encounters from searching males. On contact, all females which still have eggs to lay are mated (or remated), generally (i.e. over 75%) in their first encounter. All such females copulate for a normal duration, irrespective of previous matings. However, females which have completed oviposition are much less attractive to males on contact and though about 35% of post-oviposition females copulate as a result of their first encounter, only about half of them will have begun genital contact even if allowed six encounters with males. The female behaviour does not appear to be involved in this effect. Matings with post-oviposition females last only 43% of the normal duration. This effect may be due at least in part to the side to side ('swaying') movement performed by the female. It is extremely rare in nature for females to oviposit without a male mounted in attendance (i.e. in the 'passive phase'), though females will do so quite readily if separated artificially. The female initiates separation only after all the egg batch is laid, and after separation she flies immediately upwards and away from the dropping. Female quiescence appears to be necessary for the male to adopt the passive phase; swaying during genital contact and immediately after precedes separation without a passive phase. Females remain quiescent if they still have eggs to lay (even when already mated) and fresh dung is present, though the continuous reception of fresh dung is not necessary. Females sway fairly persistently if they have completed oviposition or there is no dung stimulus. Most females examined on arrival at the dropping (and before being found by a male) already had sperm in their spermathecae, presumably from matings at previous ovipositions since all females mate on arrival at the dung and there are several successive batches of eggs. It is predicted that receptivity before all the eggs are laid may now be of selective advantage to the female. The performance of non-receptivity as exhibited by post-oviposition females involves the female in an average rejection delay of 2.7 min. per encounter. At the average density of searching males present on the dung this rejection delay time would involve the female in much more time waste than full receptivity, since after mating the passive male undertakes the rejection of other males during oviposition. Even allowing for time wasted in recopulation following take-over (i.e. when a second male takes possession of the female), a female with full receptivity would save about 50 min. per oviposition cycle compared to one showing rejection. The passive phase is presumably of advantage to the male in preventing further inseminations, sperm from which could compete with his own for the fertilisation of the female's eggs. After oviposition, the female initiates termination of the passive phase by swaying reactions which cause the male to dismount. She then flies from the dropping.

Copper tolerance in the marine fouling alga Ectocarpus siliculosus.

Abstract: INTRASPECIFIC variation in marine algae in response to habitat conditions has been proposed1 and, in some cases2,3, demonstrated. During an investigation into the ship-fouling properties of the brown alga Ectocarpus siliculosus (Dillw.) Lyngb. we have found evidence of differential response to dissolved copper which may be associated with the habitats from which the populations were taken.

The haemoglobin constitution of infants with the haemoglobin Bart's hydrops foetalis syndrome.

Abstract: Summary. The haemoglobin constitution of 14 infants with the haemoglobin Bart's hydrops syndrome has been examined. Thirteen of the infants were stillborn or lived only a few minutes after delivery, but in one case an exchange transfusion was performed and the pattern of globin chain synthesis examined by an [H3]leucine incorporation experiment utilizing umbilical cord blood. These studies indicate that the syndrome results from a total deficiency of α-chain production. Furthermore, it has been possible to exclude the presence of fragments of α-chain longer than II residues in the cells of these infants. In each infant a small quantity of haemoglobin was found which consisted of normal γ-chains in association with chains of unique constitution. A similar component was found in trace amounts in normal umbilical cord blood. This haemoglobin may be identical with haemoglobin Portland. It is suggested that the non-γ-chain of this haemoglobin is the product of a normal foetal haemoglobin locus which produces very small amounts of gene product in normal infants but which is capable of increased activity in the presence of a partial or total deficiency of α-chains.

On the axiomatic foundations of the theory of Hermitian forms

Abstract: In recent work on some topological problems (7), I was forced to adopt a complicated definition of ‘Hermitian form’ which differed from any in the literature. A recent paper by Tits(5) on quadratic forms over division rings contains a new and simple definition of these. A major objective of this paper is to formulate both these definitions in somewhat more general terms, and to show that they are equivalent.

The Seasonal Variation of the Free and Combined Dissolved Amino Acids in the Irish Sea

Abstract: Dissolved amino acids, in both the free state and combined as polypeptides, play an important part in the marine biochemistry of nitrogen. These compounds are excreted by phytoplankton (Fogg, 1962, 1966; Stewart, 1963; Hellebust, 1965) and zooplankton (Johannes & Webb, 1965; Webb & Johannes, 1965) and are utilized by algae (Syrett, 1962), bacteria (Proom & Woiwood, 1949) and marine invertebrates (Stephens & Schinske, 1961). Experiments with cultures have shown, indeed, that some species of phyto-plankton will not grow, or grow only with difficulty, if certain amino acids are absent (Harvey, 1938; Provasoli & Gold, 1957; Droop, 1957, 1959, 1962). In addition to their direct biochemical role, amino acids may also serve to complex trace metals, such as copper and iron, and keep them readily available for assimilation by marine organisms (Harvey, 1938; Fogg, 1959; Provasoli, 1963; Kent & Hooper, 1965; Saunders, 1957).

The reproductive behavior and the nature of sexual selection in scatophaga stercoraria l. (diptera: scatophagidae). vii. the origin and evolution of the passive phase.

Abstract: The reproductive behavior of the dung fly, Scatophaga stercoraria L, has been divided into a series of separate phases; eg searching, genital contact, etc (Parker, 1970b) These are mostly self-explanatory and occur in many animal species An exception, however, is the post-copulatory passive phase oif the male In S stercoraria the average density of males searching around fresh cattle droppings (the site of mating and oviposition) is very high, especially during the population peaks (Parker, 1970a) Females lay several successive batches of eggs and visit the fresh dung only to mate and oviposit (Parker, 1970e) Genital contact begins immediately after a female arriving at the dung is captured by a searching male After copulation the male adopts the passive behavior phase by raising his abdomen away from that of the female but otherwise retaining the same mount posture The female has considerable freedoim of movement and is quite free to oviposit; the only contact maintained by the male is the grasp of his front tarsi around the junction between her thoirax and abdomen The male's middle and hind legs rest on the dung surface Ovipositing pairs are attacked repeatedly by searching males and "take-overs" (where the attacker displaces the original male and takes possession of the female) are not infrequent (Parker, 1970d) The female initiates separation after oviposition, and her behavior also determines whether or not a passive phase is adopted by the male (Parker, 1970e) Females remain quiescent only when both fresh dung is present and they still have mature eggs to lay Otherwise they show "swaying" reactions during copula and immediately after which cause the males to separate without a passive phase These reactions resemble the rejection reactions shown by many unreceptive female Diptera The term "passive phase" may be defined as a stage of the male's reproductive behavior during which he remains mounted on or otherwise attached to the female but without true genital contact between the two sexes "Copula" or "copulation" is regarded as synonymous with true genital contact Sometimes the terms "amplexus" (literally, an embrace) and "tandem behavior" have been used loosely for situations resembling passive phases "Passive phase" is used because it cointra-sts, with the phase of active sperm transfer; it is not intended to imply general inactivity of the male Passive phase males often show vigoirous rejection reactions when attacked by single males, Passive phases occur infrequently in widely separated groups, of animals, though their adaptive significance has attracted little speculation and apparently no quantitative analysis The aim of the present paper is to investigate the possible selective values of the passive phase in S stercoraria, and to consider its origin and the method by which it may have evolved

The Distribution of the Major and Some Minor Elements in Marine Animals I. Echinoderms and Coelenterates

Abstract: Many metallic elements are concentrated by marine animals to levels far in excess of their concentrations in sea water itself This concentration extends not only to those elements which are known to have biochemical functions, but also to others which have no established biological role (eg cadmium and lead) Little is known about the mechanisms by which trace elements are concentrated, or about the manner in which they are held in the tissues As a preliminary to the investigation of concentration mechanisms, reliable data are required concerning the distribution of the elements in a variety of marine animals

Effect of crazes on the propagation of cracks in polystyrene

Abstract: A study of the fracture surfaces of polystyrene has revealed a direct connection between the fracture path and the shape and distribution of crazes. The effect is demonstrated by two examples; firstly, the propagation of a crack through initially uncrazed material and, secondly, the propagation of a crack through material containing an array of planar crazes parallel to the plane of propagation. It is shown that cracks propagate preferentially along crazes and that the formation of crazes in the stress field of a propagating crack results in the “hackle” surface normally associated with the propagation of cracks at high velocities.

The properties of mitochondria enriched in vitro with cholesterol.

Abstract: 1 The unesterified cholesterol content of rat liver mitochondria can be raised from 0.04—0.06 to 0.1—0.13 μg per μg phospholipid by incubation for 16 h at 25° with plasma lipoproteins. 2 The extra cholesterol taken up by the mitochondria is roughly equally divided between outer and inner membrane fractions. 3 The NADH oxidase, rotenone-insensitive, NADH-cytochrome c reductase, fatty acid oxidase and monoamine oxidase activities of cholesterol-enriched mitochondria are similar to those of control mitchondria stored at 4° for 16 h. 4 Dinitrophenol-stimulated, Mg2+-dependent ATPase and respiratory control measurements indicated that the functional integrity of the cholesterol-enriched mitochondria is as good as that of the control mitochondria although in both respiratory control is less marked than in freshly-isolated mitochondria. 5 Succinate-cytochrome c reductase activity is much greater in cholesterol-enriched than in control mitochondria. When the mitochondrial cholesterol level is alternately raised and lowered, the succinate-cytochrome c reductase activity increases and decreases with it. 6 Cholesterol-enriched mitochondria are much more resistant to large amplitude swelling than control mitochondria, apparently because of the increased strength of the outer membrane. 7 The changes in light absorbance associated with small-amplitude swelling and shrinking of cholesterol-enriched mitochondria are much smaller than those of control mitochondria.

Temperature modulation of α- and β-adrenoceptors in the isolated frog heart

Abstract: 1. The effects of adrenaline on the isolated frog's heart at 27° C are not antagonized by phentolamine (1·5 × 10-6M) but are abolished at 7° C. 2. At 27° C isoprenaline was more potent than noradrenaline, but at 7° C noradrenaline was more potent than isoprenaline. 3. Phenoxybenzamine (1·5 × 10-5M) or dibenamine (1·5 × 10-5M) at 7° C abolished the work output induced by adrenaline. When the temperature was raised to 24° C, adrenaline caused an increase in work output. 4. It is concluded that in the isolated frog heart there are at least two pools of adrenoceptors, the availability of which can be governed by temperature.

The characterization and stereochemistry of biosynthesis of dolichols in rat liver

Abstract: It was shown that rat liver contains a series of dolichols with chain lengths of from 17 (or possibly 16) to 21 isoprene residues, the main constituent of the mixture being dolichol-18. By using double-labelled radioactive mevalonates it was demonstrated that each of these dolichols possesses three biogenetically trans-isoprene residues and that the remaining residues are biogenetically cis, suggesting that these polyprenols are biosynthesized from all-trans-farnesyl pyrophosphate by the cis additions of isoprene residues, followed by saturation of the α-isoprene residue. The results obtained with these radioactive mevalonates also indicated that the activity of isopentenylpyrophosphate isomerase is low relative to the activity of prenyltransferase in rat liver.

'We are not the only ones to blame': District Assemblies' perspectives on the state of planning in Ghana

Abstract: Planning has failed to exert effective influence on the growth of human settlements in Ghana. As a result, the growth of cities has been chaotic. The district assemblies, which are the designated planning authorities, are commonly blamed for this failure, yet little attention has been given to district assemblies’ perspectives of what factors lead to failures in planning. This paper attempts to fill this gap. Drawing on fieldwork in Ghana, it argues that, from the perspective of district assemblies, five major challenges inhibit planning, namely: an inflexible land ownership system, an unresponsive legislative framework, undue political interference, an acute human resource shortage, and the lack of a sustainable funding strategy. The paper concludes with proposals for reforming the planning system in Ghana.