Showing papers by "University of Exeter published in 1973"

Aquatic hyphomycete spora of the River Exe and its tributaries

Abstract: Water samples collected from the River Exe and its tributaries at weekly intervals during the period August 1970 to September 1971 were filtered through Millipore filters which were then stained to show the spores of aquatic hyphomycetes. Quantitative estimates of the spore content of the water are presented, and attempts are made to relate the concentration of particular species to such variables as the rate of leaf fall into the rivers, water temperature and pH.

An MMPI Source Book; Basic Item, Scale, and Pattern Data on 50,000 Medical Patients

Abstract: An MMPI Source Book. Basic Item, Scale and Pattern Data on 50,000 Medical Patients. By Wendell M. Swenson, John S. Pearson and David Osborne. Minneapolis, University of Minnesota Press and London, Oxford University Press, 1973. 150 p. 7¼“. £4.75.

The trapping of aquatic hyphomycete spores by air bubbles

Abstract: A technique is described for estimating the rate of removal of aquatic hyphomycete spores from suspension by air bubbles, and for calculating the trapping efficiency of an air bubble. Values for trapping efficiency are given for different kinds of hyphomycete spore. In general, the branched type of spore is more readily removed from suspension than spores of conventional shape, although the trapping of the sigmoid spores of Anguillospora crassa is quite effective. Evidence is presented for Varicosporium elodeae that as the complexity of branching of the spore increases, the effectiveness of trapping by air bubbles also increases. The addition of detergent causes an increase in the rate of removal of spores.

Antagonism between stilbella erythrocephala and other coprophilous fungi

Abstract: Stilbella erythrocephala, a common fungus on rabbit dung, produces a diffusible antibiotic in culture which causes significant inhibition of growth of many other coprophilous fungi, some fungal pathogens of cultivated plants, and dung bacteria. In culture on liquid malt extract, maximum antibiotic production was observed at pH 5–6 after 2 days' growth. Evidence was also obtained of antibiotic production on rabbit dung. When Stilbella was inoculated into sterile rabbit pellets along with either Pilobolus crystallina, Ascobolus crenulatus or Coprinus heptemerus, sporulation of Pilobolus ceased prematurely, sporulation of Ascobolus was completely inhibited, and sporophore production in Coprinus was slightly diminished.

Physical adsorption of nitric oxide on graphite and silica and adsorption of gases on nitric oxide preadsorbed on carbon

Abstract: Adsorption isotherms of nitric oxide on graphitized and ungraphitized samples of carbon black (Sterling FT) and on silica (Cab-O-Sil) have been measured at 775 and 902 K Isosteric heats of adsorption on the graphitized carbon at low coverage (θ Adsorption isotherms at 775 K of nitrogen, argon, carbon monoxide, krypton and oxygen have been measured on the graphitized carbon modified with preadsorbed layers of NO For all the adsorbates except Kr, the stepwise shape of the isotherm is eliminated by the preadsorption of NO The isotherms on the modified surface are compared with those on the bare surface by means of comparison plots (1) of amounts adsorbed at equal pressures

Anisotropy in the hardness and friction of calcium fluoride crystals

Abstract: Anisotropy in the Knoop indentation hardness and the friction of diamond cones on calcium fluoride crystals has been investigated at experimental temperatures from 20 to 300° C. It is shown that the directions of minimum and maximum indentation hardness, on the (001) plane, are 〈110〉 and 〈100〉 respectively whilst the 〈1¯10〉 are harder than the 〈11¯2〉 directions on the (111) plane. Also, the sliding friction in the (001) plane is greatest in the 〈110〉 directions and least in the 〈100〉 and, on the (111) cleavage plane, [¯1¯12] sliding leads to higher friction than [11¯2]. The nature of anisotropy, for both hardness and friction measurements, does not change over the experimental temperature range covered in this work. Observations on the resultant deformation are made and these anisotropic properties are explained in terms of the effective resolved shear stresses developed on the {100} 〈011〉 primary slip systems at all experimental temperatures.

Prehistoric Roads and Tracks in Somerset, England: 3. The Sweet Track.

Abstract: The excavation of the Sweet track at two sites in the Somerset Levels has yielded unique material of the late fourth millennium bc. The track was built across a reed marsh, and the builders used a variety of timber obtained from both nearby fen-wood and from the dry land of the Burtle sand and the Poldens. Pollen analyses indicate that certain areas of the Levels were particularly favourable for forest clearance and cultivation, and the debris from the track shows a range of woodwork so far unique to the British Neolithic.

Structure of microtubules: a study of freeze-etched and negatively stained microtubules from the ovaries of Notonecta.

Abstract: Insect ovaries of the telotrophic type contain large numbers of microtubules within the tubes which connect an anterior trophic region to each oocyte within the ovariole. We have examined these microtubules using the freeze-etch technique and found that our observations correspond in many ways with the image of microtubules which have been subjected to chemical fixation. Obliquely fractured microtubules show sub-filaments within their walls, while both obliquely and longitudinally fractured microtubules display a periodicity of approximately 4 nm along many of the sub-filaments. In transverse fracture, a “clear zone” can be seen around individual microtubules and this confirms that the “clear zones” which are often seen around transverse sections of microtubules, are real features and not artefacts of fixation.

Deformation of Magnesium Oxide Crystals by Softer Indenters and Sliders

Abstract: WHEN a scratch or indentation hardness measurement is made one is generally more concerned with gross changes in shape, due to macro-deformation or fracture, than in any aspects of small scale or micro-deformation which might also form a part of the permanent deformation process. Consequently, certain guide lines have been established1. The possibility of micro-deformation in a relatively hard crystal due to point contact through a significantly softer indenter or slider may have been assumed but there seems to be little published information on its nature and extent. We have recently completed some preliminary experiments on this aspect of deformation in the indentation and scratch hardness processes and the results indicate that the cumulative effects, due to repeated loading, may well play an important part in subsequent macro-deformation. Most of the experiments were carried out on magnesium oxide because the resultant distribution of dislocations could be readily observed, using the etchant perfected by Gilman and Johnston2, on a (001) plane prepared by cleavage and then chemically polished. Lead, copper and diamond cones, having apical angles of 136°, were used as indenters and sliders. The relevant diamond cone indentation hardness values for the magnesium oxide, copper and lead were 6,000 MN m−2, 980 MN m−2 and 50 MN m−2 respectively and can be assumed to be between 69,000 to 96,000 MN m−2 for diamond3.

The immune responses of dace Leuciscus leuciscm (L.) to injected antigenic materials

Abstract: The fundamental features of the primary responses of dace Leuciscus leuciscus (L.), a freshwater cyprinid, to a number of standard antigens—haemocyanin, bovine serum albumin, horse serum, a bacterial antigen and an erythrocyte suspension, were examined. The fish were capable of producing either precipitating or agglutinating antibody in response to each of these antigens. Determinations of latent periods of antibody production by dace over a range of temperatures −18, 10, 5 and 2°C, showed that although the latent periods of the primary response increased with decreasing temperature, fish were able to produce antibodies to the erythrocyte antigen at 2°C and to the Salmonella and horse serum protein antigens at 5°C. The demonstration of antibodies at 5 and 2°C suggests that the fish are capable of producing antibodies over the complete range of their normal environmental temperatures.

Gibberellins and geotropism in Zea mays coleoptiles.

Abstract: Diffusible gibberellins were obtainable in agar from excised 4 mm tips of etiolated coleoptiles of Zea mays. Placing the tips in a horizontal position increased the total yield of gibberellins by approximately five times. With horizontal tips, the ratio of gibberellin activity recovered from lower and upper halves, expressed as a percentage of total yield, was 80.76:19.24 (lower:upper).

Radioactive Marking of Small Mammals

Abstract: Summary The literature on the use of radioactive materials in various kinds of ecological work on small mammals is reviewed under three main headings–inert implants used as markers for tracing movements, external radioactive tags used for similar purposes, and metabolizable radionuclides introduced into the animals' bodies not only for direct tracing of movements of the marked individuals, but for indirect tracing by detecting radioactive excreta, and by automatic marking of offspring and ectoparasites, which can in turn be identified and traced. A comprehensive table summarizes the literature reviewed, and summarizes also the characteristics of the various radioactive isotopes used or suggested for use. Tests were carried out on various possible methods of using iodine-131 as a marker for small mammals. Intraperitoneal injection of 131-iodide as silver iodide or bound to an ion-exchange resin gave an unsatisfactorily short biological half-life for direct tracing but might be useful for detecting excreta. Silver 131-iodide incorporated in epoxy resin and encapsulated in metal or plastic could prove to be a useful implant. Silver 131 -iodide paint was quickly removed from the animals' fur by grooming, but might be useful for insects. Silver-131-iodide–Araldite mixture on a leg ring proved useful, despite the inherent disadvantages of leg rings.

Pleuropedium tricladioides gen. et sp. nov.

Abstract: A new aquatic Hyphomycete,Pleuropedium tricladioides Marvanova et Iqbal, is described from submerged deadJuncus effusus axes and from foam in mountain streams.

Microbial metabolism of alkylbenzene sulphonates. Fungal metabolism of 1-phenylundecane-p-sulphonate and 1-phenyldodecane-p-sulphonate.

Abstract: A study was made of the biodegradation of 1-phenylundecane-p-sulphonate and 1-phenyldodecane-p-sulphonate byCladosporium resinae (CMI 88968) which was capable of growth on a number of such alkylbenzene sulphonate homologues as the sole source of carbon and sulphur. The results from both whole-cell and cell-free systems indicated that the alkyl, aryl and sulphonate moieties of detergent homologues were metabolised by the fungus. The alkyl side-chain, after a presumed initial oxidation of the terminal methyl group, was subsequently oxidised by a β-oxidation pathway. Three enzymes of the β-oxidation pathway, i.e. acyl-CoA synthetase, acyl-CoA dehydrogenase and β-hydroxyacyl-CoA dehydrogenase were identified in detergent-grown cell-free extracts of the fungus. The sulphonate moiety was released as sulphate by a desulphonating enzyme. The combined results of continuous sampling programmes monitored by both TLC and sulphate appearance in the growth medium indicated that desulphonation of the aromatic moiety was an early event in the overall biodegradation of synthetic detergent homologues. The presence of 1-phenylvalerate, 1-phenylpropionate, benzoate,p-hydroxybenzoate and 3,4-dihydroxybenzoate in cells after growth on 1-phenylundecane-p-sulphonate was indicated by GLC analysis. Cells grown on 1-phenyldodecane-p-sulphonate were shown to contain 1-phenylhexanoate, 1-phenylbutyrate, phenylacetate,p-hydroxyphenylacetate and 3,4-dihydroxyphenylacetate. The aromatic nuclei remaining after alkyl side-chain biodegradation were further metabolised by an oxidation sequence involving an “ortho-cleavage” pathway. An overall metabolic pathway for the biodegradation of alkylbenzene sulphonates byCladosporium resinae is proposed.

Notes on F. Scott Fitzgerald and the Passing of the Great Race

Abstract: Nick Carraway, the narrator of Fitzgerald's The Great Gatsby (1925), is slightly taken aback by some of his host's remarks in the course of an otherwise bantering conversation during his first visit to the Buchanans' East Egg residence:‘Civilization's going to pieces,’ broke out Tom violently. ‘I’ve gotten to be a terrible pessimist about things. Have you read The Rise of the Colored Empires by this man Goddard? … Well, it's a fine book, and everybody ought to read it. The idea is if we don't look out the white race will be – will be utterly submerged. It's all scientific stuff; it's been proved … This fellow has worked out the whole thing. It's up to us, who are the dominant race, to watch out or those other races will have control of things … The idea is that we're Nordics. I am, and you are, and … And we've produced all the things that go to make civilization – oh, science and art, and all that. Do you see?

Social and Medical Factors in the use and Effectiveness of IUDs

Abstract: A cooperative international survey of IUDs has largely emphasized the medical aspects of the device; psychosocial factors on IUD use and effectiveness have not been examined until recently. Such factors as the number of doctors seeing a patient staff work load and schedule of clinic operations may play a significant role in IUD use and effectiveness. Age and parity were found to be comparable in clinics with different pregnancy and removal rates. The stricly medical approach should be extended to include the other variables associated with both providers and acceptors of the IUD service. The M 213 IUD designed to take advantage of uterine contraction so that it is "fundus" seeking was also studied. After 12 months use and compared with other devices it had a higher than average pregnancy rate a lower than average removal rate and a very low expulsion rate.

Anxiety and gaze aversion in dyadic encounters.

Abstract: Provision exists in the Argyle & Dean (1965) ‘affiliative conflict’ theory for testing a hypothesis that the frequency of gaze aversion in a dyadic encounter will increase as the anxiety of one or both of the participants increases. While these and other researchers have implied this to be the case, no systematic study of the phenomenon appears to have been undertaken. Two studies respectively involving transient and predispositional anxiety were carried out, but in neither did the results support this hypothesis.

Recognition and recall: latency and recurrence of images

Abstract: Explanations of improvements in memory through the formation of mental images require that the same image recurs when the stimulus is re-presented on the test trial. The experiment obtained information on the latency and recurrence of images to explain anomalies in recognition memory following imaging. In Part A, words of high or low I were presented one by one and subjects stopped a timer to indicate when they had formed an image to each word. The words were then presented for a second time, together with an equal number of new words. As before, subjects stopped a timer when they had formed an image. They reported whether the word had been presented before, and, if so, whether the image was the same as on the first presentation. No change was found in the latency of image formation to high I words but the latency to low I words decreased on the second presentation and the same image recurred less frequently to low I words. In Part B, pairs of words were presented. Pairs and single words from pairs were presented again, along with equal numbers of new pairs and new single words. On 94 per cent of occasions on which pairs were presented for a second time the recurrence of the same image was reported. When single words were presented the same image recurred on only 22 per cent of occasions.