Showing papers by "University of Exeter published in 1984"
TL;DR: The first major horizon of ice-rafting occurred at about 2.4 Myr, and was preceded by a minor pulse of icerafting at 2.5 Myr as discussed by the authors, and the carbon isotope record shows that the site has been bathed by a water mass of similar characteristics to present-day North Atlantic deep water at least since 3.5
Abstract: We report here that DSDP Site 552A, cored with the hydraulic piston corer on the west flank of Rockall Bank, recovered an undisturbed sequence of alternating white deep-sea carbonate oozes and dark-coloured layers that are rich in glacial debris. Oxygen isotope analysis of the sequence together with detailed nannofossil and palaeomagnetic stratigraphy shows that the first major horizon of ice-rafting occurred at about 2.4 Myr, and was preceded by a minor pulse of ice-rafting at about 2.5 Myr. The carbon isotope record shows that the site has been bathed by a water mass of similar characteristics to present-day North Atlantic deep water at least since 3.5 Myr.
1,027 citations
TL;DR: In this paper, it was concluded that the continued downward growth of the stimulated region was associated with a shearing source mechanism, and the existence of the downward growth implies an eventual curvature in the maximum stress envelope if shear failures are not to be incipient under hydrostatic pore pressure conditions.
272 citations
TL;DR: It is argued that these seasonal polyphenisms provide examples of adaptations to a repeating pattern of changing environments where the mode of selection is, in broad terms, understood.
Abstract: An explanation is developed for the adaptive significance of the forms characteristic of the dry season and wet season adult generations of some tropical butterflies. The divergent phenotypes are accounted for as adaptive responses to a shift in the optimum balance between dependence on the alternative (but interdependent) strategies of active anti-predator devices and of crypsis. The seasonal polyphenisms exhibited by the satyrines Melanitis leda (Fabricius) and Orsotrioena medus (Fabricius) and the nymphalid Junonia almana (Linne) are examined in detail. The wet season forms show prominent marginal eyespot patterns which are displayed at rest and function principally in the deflection of attacks by vertebrate predators. In contrast, the dry season forms show very small or no spots and are wholly cryptic. Wet season butterflies are more active in general than those in the dry season when aestivation behaviour is often observed. The alternative phenotypes represent responses to the differences in behaviour, environment and nature of predation. Reproductive success is optimized in each season by an interaction of phenotype and behaviour. The hypothesis must be tested in detail by an investigation of the behavioural ecology and population biology of particular species. It is argued that these seasonal polyphenisms provide examples of adaptations to a repeating pattern of changing environments where the mode of selection is, in broad terms, understood.
157 citations
TL;DR: In this paper, a study of solo and duet piano performances is described, in which the musicians gave repeat performances of the music and the expressive forms were similar in successive performances.
Abstract: Perhaps some of the most refined forms of timing arise in musical performance, particularly in the coordination between musicians playing together. Studies of timing in solo and duet piano performances are described, in which the musicians gave repeat performances of the music. In both solo and duet performances there was expressive use of timing, modulating the tempo of the music and the phase relationship between the voices, and the expressive forms were similar in successive performances of the piece. There was also evidence of separate timing control of the metre and of the production of notes and rests. Thus timing in musical performance is best modelled by assuming two levels of timekeeper, one pacing the metre and the other contained in the movement trajectories of note production, computed by motor procedure in relation to the metre. It is argued that expressive forms are derived from an interpretation of the music rather than memorized; and that coordination between voices in the music is achieve...
136 citations
TL;DR: The results suggest that newborns will reliably give novelty preferences when an infant-controlled habituation procedure is used, and give support to the model of habituation which assumes it to be an exponentially decreasing process.
Abstract: Four experiments are described in which the newborn's ability to habituate to a visual stimulus and subsequently to display novelty/familiarity preferences was explored. The same two types of stimuli, simple geometric shapes and complex colored patterns, were used throughout. The results suggest that newborns will reliably give novelty preferences when an infant-controlled habituation procedure is used. However, no reliable preferences emerged following either a brief exposure to a stimulus, or when novel and familiar stimuli were presented paired together over several trials. In experiment 4 different, novel stimuli were presented on successive infant-controlled trials and the decline in trial length observed during habituation trials was not found. Although this is further evidence that habituation to a repeated visual stimulus does occur in the newborn, half of the subjects in experiment 4 would have met the infant-controlled criterion of habituation: these results are discussed in terms of artifacts that can affect habituation. While there is considerable intra-and intersubject variability in trial duration, and in other dependent measures, the results give support to the model of habituation which assumes it to be an exponentially decreasing process.
76 citations
TL;DR: An extension of the Diffie-Hellman public key distribution system to matrix rings is described and it is shown that the number of possible secret keys is much greater for a given prime p compared to the original system.
Abstract: An extension of the Diffie-Hellman public key distribution system to matrix rings is described. Using rings of non-singular matrices over Z/pZ and upper triangular matrices with invertible elements along the diagonal over Z/pZ, it is shown that the number of possible secret keys is much greater for a given prime p compared to the original system. An outline of a method to construct the base matrix used in the system is given.
67 citations
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58 citations
TL;DR: In this article, 1 H NMR relaxation time measurements are reported for the heteropolyacids H 3 PM 12 O 40. 21 H 2 O (M = W, Mo) over a range of tempereatures.
57 citations
TL;DR: The data give strong support for Lusis's (1961) suggestion that increases in melanic frequency observed during the summer in Berlin (and in the Netherlands) can be explained by more frequent mating of melanics as a result of the effects of thermal melanism.
Abstract: Selection along clines in the ladybird adalia bipunctata in the netherlands: A general mating advantage to melanics and its consequences
52 citations
TL;DR: In this paper, a simple Markov model is used to test the hypothesis that the floristic composition of vegetation colonizing bare ground immediately after burning is the major factor influencing post-fire development in heathland vegetation.
Abstract: A simple Markov model is used to test the hypothesis that the floristic composition of vegetation colonizing bare ground immediately after burning is the major factor influencing post-fire development in heathland vegetation. Data are taken from stands of different ages at time of burning in a species-rich Calluna-Arctostaphylos heath in NE Scotland. It is shown that variation in the initial floristic composition of the stands is not, in itself, sufficient to produce model simulations which match observed trends, although altering the probabilities of transition from bare ground to other states allows more successful simulations. The model supports the hypothesis that stand age before burning influences the post-fire development through the process of colonization of bare ground. After a very severe fire post-fire development may initially depend on the formation of a moss cover, although this requires further study. It is concluded that simple Markov models can provide the basis for examining successional processes when used in a comparative way.
52 citations
TL;DR: In this paper, it was shown that rotons as well as phonons can evaporate atoms in a single-quantum process and that energy and the parallel component of momentum are conserved at the free liquid surface.
Abstract: We have shown that rotons as well as phonons can evaporate $^{4}\mathrm{He}$ atoms in a single-quantum process. Measurements of the time of flight and the angular distribution of the evaporated atoms clearly distinguish between evaporation by phonons and rotons. The results indicate that energy and the parallel component of momentum are conserved at the free liquid surface.
TL;DR: In this article, a classification of mudrocks for engineering purposes was considered necessary in order to improve the common qualitative use of a variety of geological terms, including fine-grained, siliciclastic sediment or sedimentary rock.
Abstract: Summary A classification of mudrocks for engineering purposes was considered necessary in order to improve the common qualitative use of a variety of geological terms. There has been a lack of agreement between authors on the precise definition of these terms. Mudrock is defined as a fine- to very finegrained, siliciclastic sediment or sedimentary rock. Quantitative boundaries for this group of rocks are proposed using meaningful soil and rock index parameters, at changes in mechanical or material behaviour. The basic division is between fine-grained engineering soil, non-durable rock and durable rock, at compressive strengths of 0.6 and 3.6 MN/m 2 . The mudrock soils are classified according to the British Standard Classification of Soils (BSCS) with the addition of the term silty clay. Fissile or anisotropic rocks are termed shales, including clayshales where non-durable. Isotropic ones are classed as siltstones, mudstones and claystones according to their quartz contents. Tectonically induced strength and fabric anisotropy can be important and may result in slaty shales where the rock microfabric has been well aligned. An upper compressive strength limit of 100 MN/m 2 is proposed to distinguish diagenetic mudrocks from their metamorphic equivalents.
TL;DR: The title of this paper could as well have been “The Integration of Prey over Time” because there is no evidence at all that animals can manipulate numbers in the kind of way required for division, and Charnov's’ marginal value theorem predicts that natural foraging behavior in a patchy environment will be a function of the rates which prey can be captured within each patch and within the environment as a whole.
Abstract: The title of this paper could as well have been “The Integration of Prey over Time.” We are concerned with a problem that is common to the experimental analysis of animal behavior as it occurs in Skinner boxes, and to the empirical investigation of foraging as it occurs in the animal’s natural environment. It is the problem of how a series of discrete events, deliveries of reinforcers or captures of prey, are transformed into an estimate of the density of reinforcements available on a schedule, or the density of prey present in a patch. All popular accounts both of foraging behavior and of behavior under schedules of reinforcement make use of the results of such an integration. Herrnstein’s’.’ matching law and “quantitative law of effect” predict that behavior under schedules of reinforcement will be a function of the reinforcement rates experienced under the schedules. Charnov’s’ marginal value theorem predicts that natural foraging behavior in a patchy environment will be a function of the rates a t which prey can be captured within each patch and within the environment as a whole. The functions concerned are different, but the problem is common to both. You or I , faced with the problem of estimating the rate a t which discrete events occur, would doubtless solve it by counting them, then dividing by the time that had elapsed, or the number of responses we had made. We have no evidence that animals can use this solution. So far as we can tell, the capacities of even the largest-brained birds to discriminate between numbers are quite m ~ d e s t . ~ (Other kinds of “counting” behavior, which appear to be much more a c c ~ r a t e , ” ~ turn out to be no different from the kind of noncounting mechanism we propose below.) We have no evidence at all that animals can manipulate numbers in the kind of way required for division. Besides, this solution ignores an additional, fundamental aspect of the problem: the density that is being estimated is liable to change. I n the laboratory we do, of course, change the schedules of reinforcement that our subjects experience. But, except i n the case of the transition to extinction, we very rarely study the effects of these transitions. Instead, we maintain the same conditions in force until we are sure we have achieved “steady-state” behavior, and look only at
01 Jan 1984
TL;DR: Two areas where crustaceans have already been used with success are focused, namely, the mechanism of uptake of moulting hormones and the presence and characterization of ecdysteroid receptors.
Abstract: The “classical scheme” of the action of moulting hormones in crustaceans is depicted in Fig. 1. It closely resembles the situation in insects, but some details are different. For example, a stimulatory prothoracicotropic hormone is present in insects vs a moult inhibiting hormone in crustaceans. In order to elucidate the mechanism of action of ecdysteroids, crustaceans may be used with advantage, for at least certain steps of this complex sequence, not only because of the size they can reach, but also because the overall scheme is perhaps less complex than in insects. For example, there are no JH-ecdysteroid interrelationships as in insects, since JH has never been detected in crustaceans. The present paper will, therefore, focus on two areas where crustaceans have already been used with success, namely, the mechanism of uptake of moulting hormones and the presence and characterization of ecdysteroid receptors.
TL;DR: In this article, the association of the manner of Agamemnon's death, the fatal bath and the fatal robe, with the ritual of the funeral is discussed, which will enrich our own emotional reaction to Aeschylus' presentation of this event, as well as to shed light on certain problematic passages.
Abstract: Most of the work done on tracing persistent themes and images in the Oresteia has failed to take account of the associations of the theme or image for the original audience. Some of these associations are with certain highly emotional rituals. In evoking the ritual the poet evokes also some at least of the emotion which generally accompanies its performance. I will take here as an example the association of the manner of Agamemnon's death, the fatal bath and the fatal robe, with the ritual of the funeral. This will I hope help to enrich our own emotional reaction to Aeschylus' presentation of this event, as well as to shed light on certain problematic passages.
TL;DR: Ballistospore discharge in Itersonilia perplexans is described, and evidence is presented that a drop of liquid, and not a gas bubble, develops at the hilar appendix immediately before discharge.
Abstract: Ballistospore discharge in Itersonilia perplexans is described. Evidence is presented that a drop of liquid, and not a gas bubble, develops at the hilar appendix immediately before discharge. Spores detached on a micromanipulator needle produce liquid drops. The trajectories of several spores have been plotted. The horizontal and vertical distances of discharge have been measured, and the terminal velocity of sedimentation. From these values, the initial discharge velocity has been estimated at 5.5 m s−1. Evidence is presented that discharged spores carry a negative electrical charge. Two possible mechanisms for spore projection are discussed, a rapid transference of the centre of mass of the spore associated with wetting, and a change in the electrical charge on the spore surface at wetting, followed by electrostatic repulsion.
TL;DR: The authors found that smokers held less negative attitudes about smoking, were more likely to have a father who smoked, and anticipated less parental disapproval of their smoking, and when asked to name their 5 best friends among their classmates, smokers were more than were nonsmokers.
Abstract: Administered a questionnaire to 2 samples of British 15-yr-old secondary school students: 178 Ss in an all-male school and 41 females and 59 males in a coeducational school. The measure investigated Ss' smoking attitudes and behavior and the effects of peer pressure on both. Results show that smokers (anyone who had smoked at all within the previous week) held less negative attitudes about smoking, were more likely to have a father who smoked, and anticipated less parental disapproval of their smoking. When asked to name their 5 best friends among their classmates, smokers were more likely to name other smokers than were nonsmokers. On the basis of these results, it is argued that the notion of "peer group influence" should be reconceptualized in terms of intergroup processes and social identity concerns within the peer group.
TL;DR: In this paper, the direction of the risk-benefit relationship was dependent on the issue being judged, and the importance of subject group characteristics were shown to be important influences on risk and benefit perception in certain situations.
Abstract: Previous work on perceived risk, particularly a study by Fischhoff et al. (1978), is critically examined with reference to its applicability to specific health related issues. Judgments were obtained from 159 subjects of 15 health-related items in terms of perceived risk, benefit, and a number of risk characteristics based on the Fischhoff et al. research. In addition, demographic details concerning sex of respondent, seat belt usage, smoking status, and birth order were collected. Using regression analyses it was found that the direction of the risk-benefit relationship was dependent on the issue being judged. Risk was found to be better explained by ratings of likelihood of mishap and likelihood of death as a consequence of mishap. Benefit was poorly explained by the risk characteristics and demographic data. However, subject group characteristics were shown to be important influences on risk and benefit perception in certain situations. The implications of these results for understanding behavioral decisions involving risk in relation to specific activities are discussed.
TL;DR: Experimental evidence suggests that there is a contact stimulus to germination in sigmoid conidia of aquatic fungi during flow and on coming to rest.
Abstract: Observations on the orientation of sigmoid conidia of aquatic fungi during flow and on coming to rest have been made in flat capillary tubes. Conidia are arrested by attachment at one end, and then swing round so that they are aligned parallel to the direction of the current. After a short period of attachment ‘appressoria’ and germ tubes develop where the conidium makes contact with a surface. Experimental evidence suggests that there is a contact stimulus to germination.
TL;DR: An endophytic Cryptosporiopsis sp.
Abstract: An endophytic Cryptosporiopsis sp. isolated from Vaccinium myrtillus (bilberry) produced three different antibiotic-containing fractions on TLC plates. All were inhibitory to Candida albicans , which indicated that none of them was cryptosporiopsin, the only antibiotic so far known to be produced by this genus.
TL;DR: In this paper, measurements of the bend (k 33 ) and splay (k 11 ) elastic constants and the amplitude of the smectic-like local ordering (obtained using X-ray diffraction techniques) have been made for a wide range of nematogens.
Abstract: The measurements of the bend (k 33 ) and splay (K 11 ) elastic constants and the amplitude of the smecticlike local ordering (obtained using X-ray diffraction techniques), have been made for a wide range of nematogens. The results reveal a strong correlation between k 33 /k 11 and the strength of the smectic-like local ordering. This correlation applies to nematogens with either bilayer or monolayer structures, irrespective of whether or not they exhibit a smectic phase. These results have been rationalized in more detail in terms of a recent theoretical model which calculated the elastic constants as a function of smectic-like local ordering Mesure des constantes elastiques de corubure (k 33 ) et de deformation en eventail (k 11 ) ainsi que de l'amplitude de l'ordre local de type smectique pour un large ensemble de nematogenes. Mise en evidence d'une forte correlation entre k 33 /k 11 et l'intensite de l'ordre local de type smectique. Cette correlation s'applique a des nematogenes de structure bicouche ou monocouche
TL;DR: The Kermack & McKendrick theory of epidemics has been applied to data on deaths from influenza and influenzal pneumonia in Greater London in the years 1950–78, and the estimated values of the parameters can be plausibly related to the natural history of the disease.
Abstract: The Kermack & McKendrick theory of epidemics has been applied to data on deaths from influenza and influenzal pneumonia in Greater London in the years 1950-78. As a whole the theory gives a good description of the data, and the estimated values of the parameters can be plausibly related to the natural history of the disease. However, the possibility exists that the agreement is merely empirical, and field studies would be required to confirm its validity.
TL;DR: In this article, the authors focus on the accounting aspects arising from the development of the railways and provide a background to the first government regulations, introduced in 1840, and all subsequent major developments which led up to the Railway Companies (Accounts and Returns) Act, 1911.
Abstract: This paper concentrates on accounting aspects arising from the development of the railways. Railways in nineteenth century Britain had a major influence in reshaping some of the legislative procedures in parliament, the development of the capital market, and the economy at large. A background is provided to the first government regulations, introduced in 1840, and all subsequent major developments which led up to the Railway Companies (Accounts and Returns) Act, 1911. Why had it taken over eighty years (since the first commercial railway was established in 1830) to produce a standard presentation of accounts and financial reports?
TL;DR: Evidence is presented that Tilletiopsis washingtonensis and I. perplexans may extrude a hygroscopic substance from the punctum lacrymans, resulting in rapid absorption of liquid from a humid atmosphere.
Abstract: The origin of the liquid in Buller's drop is discussed and evidence presented that Tilletiopsis washingtonensis and I. perplexans may extrude a hygroscopic substance from the punctum lacrymans , resulting in rapid absorption of liquid from a humid atmosphere.
TL;DR: In this article, the Intuitive Science: Learned or triggered? European Journal of Science Education: Vol. 6, No. 1, pp. 7-10, 1984, Theodorakopoulos et al.
Abstract: (1984). Intuitive science: Learned or triggered? European Journal of Science Education: Vol. 6, No. 1, pp. 7-10.
TL;DR: Flounders are not even a suitable host for the English freshwater strain of P. laevis although individual parasites may be carried to sea in this and other migratory fish and survive in this medium for varying periods.
Abstract: The status of flounders as hosts of Pomphorhynchus laevis and its survival in both freshwater and marine habitats was studied in the wild and by means of laboratory investigations. Natural infections were found in flounders in the euryhaline regions of the River Avon but not in adjacent or distant regions of the English Channel. Pomphorhynchus laevis of freshwater origin survived and grew but did not become sexually mature in natural infections of flounders in the Avon or in flounders maintained in fresh water and sea water in the laboratory. The position of the parasite in the alimentary canal of its host changed in flounders but not in eels in response to the changing conditions within the flounder with increasing salinity. In the Baltic Sea P. laevis grew to a larger size, became sexually mature and occupied a different position, the rectum, in both flounders and plaice. It is suggested that marine and Baltic parasites constitute a different strain of P. laevis, one which completes its entire life cycle in the marine habitat and for which flounder is the preferred host. By contrast, flounders are not even a suitable host for the English freshwater strain of P. laevis although individual parasites may be carried to sea in this and other migratory fish and survive in this medium for varying periods. The sea appears to be a major barrier to dispersal of this freshwater strain, and this largely explains the restricted and discontinuous distribution of the parasite in Britain.
TL;DR: A method using homokaryotic mycelia to investigate the dissemination and deposition of viable spores of heterothallic basidiomycetes, is described and its application discussed.
Abstract: A method using homokaryotic mycelia to investigate the dissemination and deposition of viable spores of heterothallic basidiomycetes, is described and its application discussed.
TL;DR: It is suggested that greater benefits to the child might occur where information about illness is made appropriate to the children's cognitive level, and all of the main techniques in use appear more beneficial to the patient and family than routine care.
Abstract: This paper is concerned with preparing paediatric patients for hospitalisation. It is concluded that most work has focused on children requiring short-stay hospitalisation for minor surgery. All of the main techniques in use (pamphlets, video or pre-admission nursing contact) appear more beneficial to the patient and family than routine care, but no method is superior. Little attempt has been made to modify the technique according to the age of the child. It is suggested that greater benefits to the child might occur where information about illness is made appropriate to the child's cognitive level. The implications of developmental changes in children's beliefs about health and illness for such education are discussed.
TL;DR: The psychological condition of people surviving by dialysis has been investigated using the Dialysis Problem Check-list together with appropriate ratings, and many stressing difficulties were revealed amongst a sample of dialysis patients and their partners.