Showing papers by "University of Liverpool published in 1968"
TL;DR: In this article, it was shown that if energy is supplied above a certain mean rate to such a branch, then a steady state will be reached in which a single mode of this branch is very strongly excited.
Abstract: Biological systems are expected to have a branch of longitudinal electric modes in a frequency region between 1011 and 1012 sec−1. They are based on the dipolar properties of cell membranes; of certain bonds recurring in giant molecules (such as H bonds) and possibly on pockets of non-localized electrons. In Section 2 it is shown quit generally that if energy is supplied above a certain mean rate to such a branch, then a steady state will be reached in which a single mode of this branch is very strongly excited. The supplied energy is thus not completely thermalized but stored in a highly ordered fashion. This order expresses itself in long-range phase correlations; the phenomenon has considerable similarity with the low-temperature condensation of a Bose gas. General consequences and proposals of experiments are discussed in section 3.
951 citations
TL;DR: Evolution in closely adjacent plant populations III.
Abstract: Evolution in closely adjacent plant populations III. Agrostis tenuis on a small copper mine
295 citations
TL;DR: In this article, the branch of longitudinal electric modes was used for Bose condensation and the excitation energy was channelled into the mode with lowest frequency in a manner typical for BOSE condensation.
263 citations
TL;DR: Since no evidence has been presented for the origin of breeding barriers under disruptive selection in natural populations, the occurrence of mechanisms reducing gene flow were investigated in closely adjacent plant populations at metal mine boundaries.
Abstract: THE importance of isolation in promoting population divergence and speciation has long been recognised (e.g. Mayr, 1942; Dobzhansky, 1941; Baker, 1959). Isolation was considered a prerequisite for population divergence until Thoday (1958) showed that disruptive selection could effect such divergence in the absence of isolation. Recently the occurrence of divergence in nature in the face of gene flow has been shown in Papilio dardanus (Clarke and Sheppard, 1962), Maniola jurtina (Creed et al., 1959) and various grasses (Jam and Bradshaw, 1966; Aston and Bradshaw, 1966; McNeilly, 1967). However, gene flow is not without effect. Generally it slows down population divergence (but see Millicent and Thoday, 1961, and Streams and Pimentel, 1961) and produces ill-adapted genotypes from the crossing of two adapted types. In such situations we might expect the evolution of mechanisms to restrict gene flow. Evidence for the development of breeding barriers between adjacent (parapatric), or sympatric populations, and their absence between allopatric populations of the same species or group of species, has been presented in Drosophila (Dobzhansky and Koller, 1938; King, 1947; Ehrman, 1965), cotton (Stephens, 1946), Streptanthus (Kruckeberg, 1957), Solanum (Grun and Radlow, 1961) and Gilia (Grant, 1966). The process has also been demonstrated experimentally (Knight et al., 1956) and theoretically (Crosby, 1964). In all these instances there is evidence that breeding barriers have been developed between populations that have undergone prior allopatric divergence and which have subsequently met. However, Thoday and Gibson (1962) have shown that in Drosophila divergence and the evolution of breeding barriers can occur without isolation under disruptive selection. Since no evidence has been presented for the origin of breeding barriers under disruptive selection in natural populations, the occurrence of mechanisms reducing gene flow were investigated in closely adjacent plant populations at metal mine boundaries. The evidence suggests that considerable gene flow occurs in such situations (McNeilly, 1967; McNeilly and Bradshaw, 1967) and that mine populations are the product of recent evolution by disruptive selection (McNeilly, 1967; Antonovics, 1966).
227 citations
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194 citations
TL;DR: The sociologist's interest in the entry into employment should be focused upon these two processes of occupational role allocation and socialisation as discussed by the authors, and the sociologist should be able to obtain an accurate description of how these processes take place, and to explain why they take place in the manner that they do.
Abstract: R epresentatives of various disciplines including psychology, economics and education have all examined die entry into employment. They have all defined their own particular problems that the subject matter poses and have attempted to answer them. Before the sociologist enters the field it appears sensible that he should first define his particular interests in the subject. If confusion is to be avoided the questions that the sociologist hopes to answer as a result of his examinations of the entry into employment need to be clearly declared in advance. I would like to suggest that the entry into employment embodies two major social processes. Firstly school-leavers must be differentiated and placed in their various roles within the occupational system, and secondly they must be induced to accept their new r61es as workers in the specific occupations to which they have been allocated. These processes must take place during the entry into employment in any society with a complex division of labour and in which childhood r61es are not precisely articulated with the specific adult destinations of the young. The sociologist's interest in the entry into employment should be focused upon these two processes of occupational rdle allocation and socialisation. We want to obtain an accurate description of how these processes take place, and to explain why they take place in the manner that they do.
162 citations
TL;DR: A method of measuring corneal temperature using a bolometer that does not have these disadvantages is described, together with the results obtained, and the theoretical and practical considerations in its use are discussed.
150 citations
TL;DR: Phosphatidylcholine/cholesterol dispersions are readily attacked by phospholipase D in the absence of ether but dispersions of phosphatidylethanolamine alone need ether present to facilitate enzyme attack.
Abstract: 1
Very little lipid can be extracted with diethyl ether or chloroform from aqueous dispersions of phosphatidylcholine, phosphatidylethanolamine and phosphatidic acid, or from mixed dispersions of phosphatidic acid and phosphatidylethanolamine with cholesterol. Nearly all of the cholesterol and about 60% of the phosphatidylcholine can be removed from a dispersion of these two lipids in equimolar proportions but not from a dispersion of two molecules of phosphatidylcholine to one molecule of cholesterol.
2
NaCl and CaCl2 greatly increase the extraction of lipids from phosphatidylcholine and phosphatidylcholine/cholesterol dispersions whereas urea and dimethylsulphoxide prevent extraction.
3
Cholesterol molecules readily exchange between rat erythrocytes and dispersions of equimolar proportions of phosphatidylcholine and cholesterol.
4
At lower proportions of cholesterol, the dispersions remove cholesterol from the ghosts. Up to 60% of the sterol can be removed from the ghost membrane.
5
Phosphatidylcholine/cholesterol dispersions are readily attacked by phospholipase D in the absence of ether but dispersions of phosphatidylcholine alone need ether present to facilitate enzymic attack.
6
These properties are compared with those of soluble and structural lipoproteins.
130 citations
TL;DR: In this article, a chromatographic method for the fractionation of the α and β-chains of human haemoglobins was described, which has been used extensively in various laboratories.
Abstract: WE have described a high-resolution chromatographic method for the fractionation of the α and β-chains of human haemoglobins1,2 which has been used extensively in various laboratories.
129 citations
TL;DR: Garnet, biotite and host rock have been analysed along a traverse from the garnet isograd to the kyanite zone in the Dalradian of Central Perthshire, Scotland as discussed by the authors.
Abstract: Garnet, biotite and host rock have been analysed along a traverse from the garnet isograd to the kyanite zone in the Dalradian of Central Perthshire, Scotland. FeO and MgO increase and MnO and CaO decrease in the garnet with increasing grade. Microprobe analyses of the garnets reveal zoning, which indicates that a garnet crystal as a whole does not equilibrate with the matrix during growth. Coexisting biotite varies in composition as a result of the abstraction of MnO, FeO etc. from the rook by the growing garnet, i.e. the mg/mg + fe ratio increases with grade. The microprobe analyses also reveal the size of the system from which garnet abstracted material varied from 0.100 to 2.000 g and the nucleation was frequently “instantaneous”. It also reveals the equilibrium or non-equilibrium nature of the assemblage, and explains the variation in garnet composition with grade in terms of a segregation model with a changing distribution coefficient. Primary chlorite was analysed from rocks near to the garnet isograd containing garnet and biotite. It has a similar mg/mg + fe value to the coexisting biotite. The results show that the three phase field defining the garnet isograd moves towards the mg corner with increasing grade. The higher grade fields lie to the mg rich side of the three phase field so that the sequence of mineral assemblages across the Barrovian zones in Perthshire, from the garnet isograd to the kyanite zone, can be summarized and displayed on a phase diagram.
TL;DR: In this article, a series of deep layers were observed at two stations roughly mid-way between Cape St Vincent and Madeira, and were characterized by discrete temperature and salinity steps of the order of 0·25°C and 0·044% respectively and of thickness from 15 to 30 m.
TL;DR: In this article, a selection of samples representing extremes of magnetic and opaque petrological properties represented in a single lava has been used to investigate the possibilities of obtaining the intensity of the ambient field (FANC) at the time of extrusion of the flow.
Abstract: Summary
A selection of samples representing extremes of magnetic and opaque petrological properties represented in a single lava has been used to investigate the possibilities of obtaining the intensity of the ambient field (FANC) at the time of extrusion of the flow.
Two methods have been used to obtain values of FANC; the first using a version of Thellier's method of comparison of partial natural remanences (PNRMs) and partial thermoremanences for several temperature intervals and the second using Van Zijl's method of comparison of progressive a.c. demagnetization of the NRM and of a laboratory TRM.
Initial assessment of the results was based on the similarity of form of natural and laboratory weak field remanence demagnetization curves together with the internal consistency of apparent FANC values. Using these criteria, results from a number of samples give acceptable values for FANC. While mean values for these samples from the two methods are not significantly different, the a.c. method gives the highest internal consistency; the RMS error of the mean value being ±3 per cent against 8 per cent for the PNRM-PTRM method. The overall mean value for FANC was 0.38 Oe corresponding to a VDM (virtual dipole moment) of 7-2 × 1025 c.g.s. units.
Clear relationships were found to exist between the strong field magnetic and opaque petrological properties on the one hand, and their suitability for FANC measurement on the other. Suitable samples were characterized by reversible strong field heating curves with single high Curie points, high titanomagnetite deuteric oxidation (magnetite oxidation numbers of 3.3 to 4.4, the highest value found in the flow) and the absence of titanomagnetite granulation. Unsuitable samples were characterized by double Curie points, magnetite oxidation numbers of less than 3.3 and, in four of five samples, titanomagnetite granulation.
TL;DR: There is rapid and complete! absorption of the drug giving an initial high blood level and the greater part of the isoniazid appears in the urine either unchanged or enzymatically biotransformed into metabolites, within 24 hours of oral administration.
Abstract: Isoniazid ( 1-isonicotinyl hydrazine) was first synthesized by Meyer and Mally in 1912 but its chemotherapeutic value was not discovered until forty years later. Grunberg and Schnitzer ( 1952) and Grunberg, Leiwant, DAscension and Schnitzer (1952) showed that the compound had bacteriostatic action against Mycobacferium tuberculosis strain H37Rv in vitro and that it protected mice from developing tuberculosis when they were given i.v. injections of tubercle bacilli. Robitzek, Selikoff and Ornstein (1952) and Selikoff and Robitzek (1952) then showed that the compound was effective in the treatment of tuberculosis in man. A considerable amount of work has been carried out on the metabolism of isoniazid both in animals and in man. These studies have shown that there is rapid and complete! absorption of the drug giving an initial high blood level. As this falls the greater part of the isoniazid appears in the urine either unchanged or enzymatically biotransformed into metabolites, within 24 hours of oral administration (Elmendorf et al., 1952; Barclay et al., 1953). A large variation in the metabolism of isoniazid was found to exist among human beings by Bonicke and Reif (1953); Hughes ( 1953) ; Hughes, Biehl, Jones and Schmidt (1954) and Hughes, Schmidt and Biehl (1955). The latter workers studied the products excreted in the urine after isoniazid was given to human beings and found that: (1) all the drug given could be accounted for; (2) isoniazid was found in the urine as free unchanged drug, as acetyl isoniazid, as isonicotinic acid and in small quantities in the form of other metabolic products; (3) there was an inverse relationship between the percentage of the given dose which is recovered as free drug and that recovered as acetylated derivative. The percentage recovered as acetyl isoniazid varied from 14 to 70 percent of the dose given, and (4) the pattern of excretion for a given subject remained constant even when the drug was given daily for months. Distribution histograms of the percentage of the administered isoniazid excreted in the free unchanged form in the urine were given by Biehl (1956, 1957). These were bimodal suggesting that subjects might belong to one of two classeseither rapid or slow inactivators.
TL;DR: The salt tolerance of populations of Festuca rubra L., which occurs in both the lower and upper regions of salt marshes and in the adjacent non-saline uplands, and of Agrostis stolonifera L. which coexists with Festuca in the upper marsh and upland are examined.
Abstract: ALTHOUGH the tolerance of plants to salt is of great economic importance and has received detailed attention, data for contrasting populations of species that occur naturally in saline and non-saline habitats are limited. Demonstrations of the significance of salt in the distribution of forms of Typha by McMillan1 and McNaughton2 are notable exceptions. We have therefore examined the salt tolerance of populations of Festuca rubra L., which occurs in both the lower and upper regions of salt marshes and in the adjacent non-saline uplands, and of Agrostis stolonifera L. which coexists with Festuca in the upper marsh and upland. Five such populations were collected from each of two geographically separate but otherwise similar sites (Aber, Caernarvonshire and Malltraeth, Anglesey).
TL;DR: In P. memnon the dominance relationships of the monomorphic tailed and tailless condition indicate that dominance can be evolved even when the characters concerned are not polymorphic, which contrasts with the genetic control of Mullerian mimicry as evidenced in the Heliconids.
Abstract: Papilio memnon is a swallowtail butterfly widely distributed in south-east Asia. The females are highly polymorphic and many of them are mimetic. The mode of inheritance of seventeen of the female forms is reported. In contradistinction to earlier work it has been shown that they are controlled by what appears to be a series of at least eleven autosomal alleles at one locus, sexcontrolled to the female in effect. There is evidence, however, that the locus is complex, comprising at least three closely linked loci with occasional occurrence of crossing over between them. Two characters which are not polymorphic and one which may be polymorphic are controlled by genes unlinked to the complex locus (the super-gene). In general, dominance is complete between sympatric forms but absent when they are allopatric. The resemblance between the mimetic forms of P. memnon and their models is greater in the genecomplex of a race in which the allelomorph occurs than in hybrids with a race in which it does not. Thus in no case is the resemblance better in the race cross, in ten cases there is no change and in thirty-five the mimicry is less good. The genetic control of the polymorphism in P. memnon shows remarkable parallels with that in P. dardanus and provides further supporting evidence for Fisher’s and Ford’s view that mimicry evolved gradually by adjustment of the gene-complex as a result of natural selection favouring those wing patterns which most closely resembled the models. Furthermore, as in P. dardanus, the mimicry is controlled by what appears to be a super-gene, adding weight to the conclusion that the genetic control of the polymorphic Batesian mimicry has evolved gradually by the accumulation of closely linked allelomorphs in advantageous combinations. This contrasts with the genetic control of Mullerian mimicry as evidenced in the Heliconids. In P. memnon the dominance relationships of the monomorphic tailed and tailless condition (excluding the form achates ) indicate that dominance can be evolved even when the characters concerned are not polymorphic. In addition, the lower frequency of dominance between allopatric forms than between sympatric ones is strongly in favour of the view that dominance has evolved. Similar evidence has been found from breeding work in the Heliconids and in P. dardanus ; however, the phenomenon is not confined to mimetic situations since there is also evidence for the evolution of dominance in other polymorphisms including industrial melanism.
TL;DR: The use of tritium labelling has shown that 3,3-spirocyclopentanoindolenine is an intermediate in the BF3 catalysed cyclization of 4-(3-indolyl)butanol to tetrahydrocarbazole as discussed by the authors.
TL;DR: It is shown that the richest variation in pigment structures occurs in the genus Primula, and the rare 7- O -methylated anthocyanin hirsutin is confined to this genus and occurs in all subgenera except Auganthus, where it is replaced by malvin or malvidin 3-glucoside as the principal petal pigment.
TL;DR: A number of 3,3-dialkyl indolenines have been prepared by alkylation of the Grignard derivatives of 3-alkyl indoles, the structures of which were determined by examination of their NMR spectra in trifluoroacetic acid as discussed by the authors.
TL;DR: In this article, attempts to isolate 3,3-spiro-cyclic indole intermediates in the cyclization of benzylidenetryptamines to tetrahydro-β-carbolines are described.
TL;DR: In this article, the opal contents of a series of siliceous deep-sea sediments have been determined by an infrared technique, and its applicability to other types of marine sediment is discussed.
TL;DR: In this paper, the rate-controlling mechanisms for Zr-O alloy crystals, in the range 77-473°K, have been determined by means of differential strain-rate and differential temperature techniques.
TL;DR: In β-thalassaemia translation of haemoglobinβ-chain mRNA appears to be normal, which suggests that defective regulation of mRNA production is probably responsible for the reduced rate of β-chain synthesis in this disorder.
Abstract: In β-thalassaemia translation of haemoglobin β-chain mRNA appears to be normal. This suggests that defective regulation of mRNA production is probably responsible for the reduced rate of β-chain synthesis in this disorder.
TL;DR: Since best L1 approximations have only recently been readily obtained, some numerical evidence is presented with which to judge the extent of the improvement over orthodox least‐squares approximation.
Abstract: When estimating the true form of experimental data that contain some very inaccurate points, the assumption that L1 approximation is superior to L2 approximation can easily be justified theoretically This is an old idea, but since best L1 approximations have only recently been readily obtained, we present here some numerical evidence with which to judge the extent of the improvement over orthodox least‐squares approximations
TL;DR: The exchange of cholesta-4,6-dien-3-one between erythocyte ghosts and lecithin/steroid dispersions or β-lipoproteins is much more rapid than that of cholesterol.
Abstract: 1
The dispersion of various steroids in aqueous solution with ovolecithin was investigated and the following molar ratios of lecithin to steroid obtained: cholesterol, 1:1; 7-dehydrocholesterol, 13.3:1; ergosterol, 13.1:1; sitosterol, 2.0:1; sterophenol 4.2:1; cholesta-4,6-dien-3-one, 2.0:1; cholest-4-en-3-one, 1.7:1.
2
The cholesterol contents of sterol-depleted cellular membranes can be restored to their original level by incubation with plasma or an equimolar dispersion of cholesterol and ovolecithin, in the presence of 10% dimethylsulphoxide (v/v).
3
Cholesta-4,6-dien-3-one, cholest-4-en-3-one, 7-dehydrocholesterol and sterophenol can exchange readily with the cholesterol erythrocyte ghosts and can replace cholesterol molecules removed from the membrane. Ergosterol can do so only to a very limited extent.
4
7-Dehydrocholesterol exchanges between rat erythrocyte ghosts and human piasma β-lipo-proteins in the same way as cholesterol. Cholesta-4, 6-dien-3-one and cholest-4-en-3-one also exchange but, in addition, there is a net uptake of these steroids by β-lipoproteins. The extra steroid entering the lipoproteins is probably dissolved in the hydrophobic core of the latter.
5
The exchange of cholesta-4,6-dien-3-one between erythocyte ghosts and lecithin/steroid dispersions or β-lipoproteins is much more rapid than that of cholesterol. The rate of exchange of the dienone, like that of cholesterol, is increased by the addition of a small quantity of dismethylsulphoxide to the medium.
TL;DR: In this paper, an infra-red technique is described which may be used for the rapid, accurate determination of quartz in sediments and sedimentary rocks, and the technique utilizes the introduction of samples to the spectrophotometer in a solid form as KBr discs.
TL;DR: Results show the contribution of the arm action in the vertical jump; two distinct peaks in the forces evoked during the sprint start; the absence of a braking thrust during the early strides of a sprint run and the relatively large braking force inherent in constant-speed running and hurdling.
Abstract: A force platform was used in conjunction with a cine camera to investigate the mechanics of several different kinds of athletic activity. Records of the components of thrust at the feet of an athlete were obtained for the vertical jump, the sprint start, the second step of a sprint run, constant-speed running, hurdling, shot putting and weight-lifting. Subsequently the records were related to the body movements as shown on the film. Results show, among other things: the contribution of the arm action in the vertical jump; two distinct peaks in the forces evoked during the sprint start; the absence of a braking thrust during the early strides of a sprint run and, in contrast, the relatively large braking force inherent in constant-speed running and hurdling; the change in direction of the horizontal thrust during shot putting; the exploitation of excess bar momentum in weight-lifting.
TL;DR: This series consists of 33 cases; all the specimens were obtained by abdominal hysterotomy with the amniotic sac intact and the fetuses were dissected and no congenital abnormalities were found.