Showing papers by "Lancaster University published in 1977"
TL;DR: Injection of basic magma into acid magma causes superheating of the acid and vigorous convection as discussed by the authors, which can lead to an explosive acid eruption in volcanic edifices.
Abstract: Injection of basic magma into acid magma causes superheating of the acid magma and vigorous convection. Vesiculation induced by convection and increased magma pressure fractures the volcanic edifice triggering an explosive acid eruption. The 1875 plinian eruption of Askja, Iceland is an example of an explosive eruption triggered by magma mixing.
732 citations
TL;DR: This paper developed an analytic foreign policy model of aid allocation, which suggests that the provision of aid leads to the establishment of commitment and dependency, enabling the donor to realize certain foreign policy utilities.
Abstract: Two views, founded on divergent rationales, have been used to explain the allocation of official bilateral aid. One view explains the allocation of aid in terms of the humanitarian needs of the recipient, the other in terms of the foreign policy interests of the donor. Although the foreign policy view is now clearly dominant, it has not been developed systematically. This paper initially develops an analytic foreign policy model of aid allocation. The model suggests that the provision of aid leads to the establishment of commitment and dependency, enabling the donor to realize certain foreign policy utilities. These utilities in turn allow the donor to pursue its interests. These interests may be ordered into five substantive foreign policy models. The main research objective of the paper is to test these models in the context of U.S. aid by making a cross-national, longitudinal study of the distribution of U.S. aid over the years 1960- 1970. We find that the foreign policy model which best explains the allocation of U.S. aid is one that is consonant with the political interpretation of imperialism.
375 citations
TL;DR: Co-ignimbrite ashes as discussed by the authors are a type of fine-grained air-fall ash associated with many ignimbrites, and they have crystal/glass ratios systematically lower than artificially crushed pumice from the same ignimrites.
301 citations
TL;DR: In this paper, the sources of lead input to the highway environment are described and the subsequent airborne and waterborne dispersal to the receiving waters discussed in detail, and the available information on each factor critically evaluated.
119 citations
116 citations
TL;DR: In this article, a review of experimental data shows that, when conditions are appropriate for settling, the terminal velocities of nodules in magmas are substantially slower if a Bingham rather than Newtonian Model is assumed.
109 citations
TL;DR: In this article, a universal formula which expresses flow dimensions in terms of fluid properties, flow rates and slopes has been derived theoretically and tested by means of experimental models and data from terrestrial lava flows.
Abstract: Flow shapes in Mare Imbrium, Copernicus, Tycho and Aristarchus have been related to lava properties by assuming that lavas have Bingham rheology. A universal formula which expresses flow dimensions in terms of fluid properties, flow rates and slopes has been derived theoretically and tested by means of experimental models and data from terrestrial lava flows. It is now possible to determine flow rates and yield stresses - both of which are related to the composition of lavas - from photographs of flow remnants. Results are presented for the lunar flows under study. Flow rates in Mare Imbrium are found to be very high by terrestrial standards. This is an important clue to the mechanism of formation of lunar sinuous rilles, which may be products of erosion by melting beneath turbulent lava flows.
100 citations
TL;DR: In this article, a single pulse time of flight technique has been used to determine the drift velocity v of the negative ions injected into liquid 4He from a field emission source, and the experimental results are in good agreement with Landau's theory of superfluidity.
Abstract: A single pulse time of flight technique has been used to determine the drift velocity v of the negative ions injected into liquid 4He from a field emission source. Measurements of v as a function of temperature T, pressure P and electric field E are presented within the range: 0.29 < T < 0.5 K; 21 x 10^5 < P < 25 x 10^5 Pa; 1 < E < 300 kV/m. The experimental results are in good agreement with Landau's theory of superfluidity. The data are used to demonstrate the inapplicability of two theories of super critical dissipation: by Takken, based on an assumption of coherent roton emission; and by Bowley and Sheard, based on the assumption of incoherent single-roton emission. The results are, however, shown to be in excellent agreement with Bowley and Sheard's incoherent two-roton theory, and the data are used to derive a numerical value of the matrix element. characterizing two-roton emission. The surprising absence of the single-roton emission process is discussed, and an upper bound is placed on the relevant matrix element.
87 citations
84 citations
TL;DR: In this paper, the authors analyse certain aspects of the debate between David Brewster and William Whewell concerning the probability of extra-terrestrial life, in order to illustrate the nature, constitution and condition of natural theology in the decades immediately preceding the publication in 1859 of Charles Darwin's Origin of species.
Abstract: Summary The object of this study is to analyse certain aspects of the debate between David Brewster and William Whewell concerning the probability of extra-terrestrial life, in order to illustrate the nature, constitution and condition of natural theology in the decades immediately preceding the publication in 1859 of Charles Darwin's Origin of species. The argument is directed against a stylised picture of natural theology which has been drawn from a backward projection of the Darwinian antithesis between natural selection and certain forms of the design argument. Contrary to the popular image of natural theology as an essentially static, autonomous and monolithic set of presuppositions about the existence of design in nature, the paper underlines the existence of a fundamental divergence of strategies within natural theology, a divergence that, in the case of Brewster and Whewell, can be correlated with the religious cultures to which they most closely belonged. The fact that, in the plurality of worlds...
77 citations
TL;DR: Summary.
Abstract: Summary. 1. P.spwnarius nymphs selected young, upper leaves of Xanthium strumarium plants, which have a relatively high amino acid concentration in the xylem sap.
2. Nymphs selected or rejected a host leaf as a feeding site after a test ingestion of plant sap.
3. Nymphs fed on detached leaves kept with their petioles in a solution of amino acids, in preference to leaves with petioles in a solution containing no amino acids.
4. Nymphs caged on leaves with relatively high amino acid concentrations in the xylem sap suffered a lower mortality after 7 days than nymphs caged on leaves with low amino acid concentrations in the xylem sap.
5. Mean excretory rate increased with the increase in the amino acid concentration in the xylem sap for third and fourth instar nymphs, and adults, but not in fifth instars.
TL;DR: It is concluded that Piaget's search for generalities in cognitive development has been unsuccessful, and that an approach based upon a skill-integration model might be more profitable.
Abstract: Summary. The relationships between Piaget's theory and education are discussed. The accumulated data from studies based upon the theory are examined in terms of (i) shared assumptions which govern the interpretation of replication studies, (ii) the extent to which a stage can be meaningfully defined, and (iii) the nature of the developmental process proposed by the theory.
It is concluded that Piaget's search for generalities in cognitive development has been unsuccessful, and that an approach based upon a skill-integration model might be more profitable.
TL;DR: In this paper, a dynamic mechanical study of four blends of PVdF and PMMA plus the constituent homopolymers indicates that these two polymers are partly compatible, but that a crystalline PVdf phase also exists.
TL;DR: In this paper, a new technique is described for measuring the adhesion between a sharply curved metal point (platinum, tungsten, titanium, nickel or gold, with a radius of curvature typically 300 nm) and a flat surface.
Abstract: A new technique is described for measuring the adhesion between a sharply curved metal point (platinum, tungsten, titanium, nickel or gold, with a radius of curvature typically 300 nm) and a flat surface (platinum, tungsten, cobalt, silicon or graphite). Adhesion forces as small as 100 nN can be measured with a sensitivity (limited by friction and vibration) of 20 nN, and the electrical resistance of the contact region is measured as a function of positive and negative load. Any plastic deformation of the metal point, as well as its cleanliness, is monitored by current and voltage measurements on electrons drawn by field emission from the point before and after contact.
TL;DR: The kinetics of the free-radical copolymerisation of styrene and maleic anhydride at 60° in bulk and in several solvents have been studied in this paper.
TL;DR: The critical transition in social policy in nineteenth-century Britain, it is still generally believed, was the change from individualism to collectivism as mentioned in this paper. Yet since Dicey came under fire in the late 1950s, there has been no accepted consensus about how and when this transition came about.
Abstract: The critical transition in social policy in nineteenth-century Britain, it is still generally believed, was the change from individualism to collectivism. Yet since Dicey came under fire in the late 1950s, there has been no accepted consensus about how and when this transition came about. Dicey himself, who was not strictly a historian but a theorist of jurisprudence, held a naive view of how things happen, how policy changes and is translated into law: a great thinker thinks, and converts disciples, who in turn contrive to turn the master's thoughts into the dominant wisdom or accepted common sense of the age, which then finds its way on to the Statute Book. In this way he arrived at his famous tripartite division of the nineteenth century into three periods of public opinion, government policy, and legislation: the first, up to 1825 or 1830, the period of Old Toryism, legislative quiescence, or Blackstonian optimism, dominated by Sir William Blackstone; the second, from about 1830 to 1865 or 1870, the period of Benthamism or Individualism, dominated by Jeremy Bentham and his disciples; and the last, from 1865 or 1870 to the time of his lectures on Law and Opinion published in 1905, the period of Collectivism, dominated, it seems, by no great thinker of powerful mind and principle, but merely by the pragmatic need to propitiate the emerging and increasingly powerful working-class voter. It is surprising that Dicey could not find a great thinker on whom to serve an affiliation order for fathering collectivism.
TL;DR: The lower Toluca Pumice bedeckt ungefahr 400 km2 and has a Volumen of rund 0,33 km3 (porenfrei gerechnet von 0,16 km3). Nach der 10-cm-Machtigkeitskurve zeigt er einen nordostgerichteten Verbreitungsfacher.
Abstract: Die Unteren und die Oberen Bimssteine des Toluca sind dacitische air fall-Ablagerungen, die vor etwa 24 500 bzw. 11 600 Jahren gefordert wurden. Der „Lower Toluca Pumice“ bedeckt ungefahr 400 km2 und hat ein Volumen von rund 0,33 km3 (porenfrei gerechnet von 0,16 km3). Nach der 10-cm-Machtigkeitskurve zeigt er einen nordostgerichteten Verbreitungsfacher. Der „Upper Toluca Pumice“ bedeckt mehr als 2000 km2; sein Volumen betragt rund 2,3 km3, wenn man die 40-cm-Machtigkeitskurve zugrundelegt. Das Gesamtvolumen durfte bei 3,5 km3 (porenfrei gerechnet bei 1,54 km3) liegen. Sein symmetrischer Verbreitungsfacher hat die Richtung N 65° E.
TL;DR: It is concluded that whilst elevated concentrations may exist in the vicinity of petrol stations and cold choked vehicles, tetraalkyl lead compounds typically account for only about 1–4% of total lead in urban air.
TL;DR: In this paper, air polluted with parts 10~8 concentrations of NO and NO2 significantly reduced the rate of growth of tomato seedlings, and the inhibition of growth would be sufficient to reduce or even nullify the benefits of CO2 enrichment under conditions of low light intensity in winter.
Abstract: Air polluted with parts 10~8 concentrations of NO and NO2 significantly reduced the rate of growth of tomato seedlings. These two pollutants are known to occur in glasshouse atmos pheres enriched with CO2 from propane or kerosene burners. The inhibition of growth would be sufficient to reduce, or even nullify, the benefits of CO2 enrichment under conditions of low light intensity in winter.
TL;DR: In chapter xxv of Il Principe, Machiavelli refers very briefly to men's goals, saying that in the things that lead to the end that everyone has in view, namely glory and riches (cioe glorie e ricchezze), men proceed in different ways as mentioned in this paper.
Abstract: In chapter xxv of Il Principe, Machiavelli refers very briefly to men's goals, saying that ‘in the things that lead to the end that everyone has in view, namely glory and riches (cioe glorie e ricchezze), men proceed in different ways.’ L. Arthur Burd observes that ‘Machiavelli dispatches in this one short sentence a question which was usually discussed at length in the earlier political manuals: what is it, namely, that furnishes the motives of action?’ Glory was one of the most important ideas in Renaissance thought, and Machiavelli's thought can be understood only imperfectly if the part that gloria played in it is not grasped; yet inexplicably this theme has been almost entirely neglected.
TL;DR: In this article, single-station and inter-station transfer functions are derived from data recorded by a magnetometer array in and around the Kenya Rift Valley. But they are not used to simulate the anomalous internal fields associated with regional current flow at a particular azimuth.
Abstract: Summary. Single-station and inter-station transfer functions are derived from data recorded by a magnetometer array in and around the Kenya Rift Valley. Different methods of presentation of the transfer function estimates are compared in terms of their ability to define lateral variations in electrical conductivity. When, as in East Africa, the conductivity structure is complex and three-dimensional, by far the most useful method of presentation is to use the transfer functions to simulate the anomalous internal fields associated with regional current flow at a particular azimuth. The use of inter-station rather than single-station transfer functions is almost essential where the amplitudes of anomalous horizontal fields are of the same size or greater than the normal fields. Horizontal field transfer functions prove to be just as useful as those usually calculated for the vertical component, and provide strong additional constraints on the internal current system.
Maps of simulated vertical and horizontal fields of internal origin indicate the importance of current channelling around the Rift Valley. A conductor just to the east of Nairobi apparently funnels regionally induced currents into two conductors associated with the Rift and dome; one at shallow depths beneath the Rift floor, and a deeper body to the east.
TL;DR: In this paper, the authors focus on the question: what is it about management development programs that determines what effect they have, in terms of the learning that people take away from them?
Abstract: In this paper we are concerned with the question: what is it about management development programmes that determines what effect they have, in terms of the learning that people take away from them? This question, and our attempt to contribute to an answer to it, will be of interest to all those who are directly or indirectly concerned with designing such programmes (we use the term ‘management development programmes’ to denote any form of event intended to influence management performance through a learning process).
TL;DR: In the absence of sea water, high temperature caused not only severe inhibition of germination but also permanent injury to the seeds, which helps to explain the germination behaviour of the species in nature.
Abstract: The seeds of Crithmmm maritimum L. were germinated floating on various concentrations of sea water up to 50% at constant temperatures of 5, 10, 15, 20, and 25°C and at alternating temperatures of 5 and 15°C. 5 and 25°C. and 15 and 25°C. Significantly higher germination was obtained at alternating than at constant temperature. When two constant temperatures at which no germination occurred were alternated, good germination was obtained. There was reduced germination and increase in time of first germination as sea water concentration increased, in the absence of sea water, high temperature caused not only severe inhibition of germination but also permanent injury to the seeds. The results help to explain the germination behaviour of the species in nature.
TL;DR: In this article, the authors reported a correlation between the sum of the differences between the liquid and ligand values of the ν 1, ν 2, ν 3, λ 4, λ 5, ǫ 4,  6,  7 and  14 modes of 4-methylpyridine and the strength of the metal-nitrogen bond.
TL;DR: In this article, an ansatz for the supervierbein in the (2 + 2)-dimensional superspace appropriate for the spinning string was presented. But it was shown that the ansatz can be obtained in an ordinary two-dimensional space, by substituting into a superspace action and integrating over the Grassmann coordinates.
TL;DR: Nouns acquired relatively early or late in life were tachistoscopically presented left or right of a central fixation point and yielded the field by age-of-acquisition interaction, predicted on the argument that words learned early in life are bilaterally represented in the cerebral hemispheres, whereas later acquired words tend to be lateralized in the left hemisphere.
TL;DR: The available distributional data for all known arctic coccolithophorids are summarized and the conclusion is drawn that collectively they may represent a highly selected community adjusted to arctic conditions and perhaps able to perennate locally but ultimately derived by immigration from the north Pacific.
Abstract: Two new genera of coccolithophorids, one with two species, have been described and illustrated by means of electron microscopy of wild material from various sources in the northern or southern hemisphere. The main diagnostic features of the new genus Wigwamma (type species W. arctica sp.nov.) include 'ring-shaped' coccoliths, attached to the edges of unmineralized plates with characteristic surface patterning, and with some or all carrying superstructures composed of four (or sometimes two) rod-shaped crystallites, converging to a point distally and attached proximally to the subtending calcified scale-rim in a characteristic manner. After comparisons with the unmineralized scales of Chrysochromulina, these coccoliths are interpreted as equivalent to the bases, including the support struts, of certain spined scales comparable in a general way with those of C. pringsheimii but with the spine itself undeveloped or vestigial. Analogous changes, carried out independently and with many differences of detail implying a different prototype source, are inferred to explain the coccolith morphology of another new genus, Calciarcus, at present only known in a preliminary way in the north Pacific (near Homer, S. Alaska). The coccoliths of this organism have been investigated chemically by means of the electron probe CORA. Further comparisons between Wigwamma, more especially W. annulifera sp.nov., and other coccolithophorids, notably Ceratolithus, Pappomonas and Papposphaera have emphasized the value of crystallographic details as taxonomic and phyletic markers, in situations where coccolith morphology as a whole is equivocal as a result of convergence. The available distributional data for all known arctic coccolithophorids are then summarized and the conclusion is drawn that collectively they may represent a highly selected community adjusted to arctic conditions and perhaps able to perennate locally but ultimately derived by immigration from the north Pacific. Other conclusions to which the arctic coccolithophorids collectively have led are summarized in a final paragraph.
TL;DR: It is concluded that malate transport to and from the subsidiary cells is not an essential part of the stomatal mechanism, and carboxylation of phosphenolpyruvate plays no major part in the formation of malate in guard cells.
Abstract: SUMMARY
After they had been ‘isolated’ by a low pH treatment which destroyed all the other cells of the epidermis, stomatal guard cells retained the capacity to produce malate when presented with fusicoccin as a stimulus to opening. For a given level of stomatal opening, the amount of malate in epidermis with isolated stomata was practically the same as in intact epidermis. It is concluded that malate transport to and from the subsidiary cells is not an essential part of the stomatal mechanism. Changes in CO2 concentration over the range 0–100 ppm affected neither stomatal aperture nor malate levels in epidermis of Commelina communis. This suggests that carboxylation of phosphenolpyruvate plays no major part in the formation of malate in guard cells.