Showing papers by "Open University published in 1973"
TL;DR: In this paper, evidence from the Troodos Massif for the origin of the ocean floor is discussed and a detailed model formulated, and the authors propose a new model for ocean floor discovery.
Abstract: Evidence from the Troodos Massif for the origin of the ocean floor is discussed and a detailed model formulated.
234 citations
TL;DR: In this article, the authors introduced the concept of ensembles to describe equilibrium and nonequilibrium macroscopic systems, and tried to justify the use of Ensembles, and to determine whether the Ensemble Evolution evolved as expected from none-quilibrium to equilibrium, they introduced further concepts such as "ergodicity" and "coarse graining".
Abstract: The founding fathers of statistical mechanics, Boltzmann, Maxwell, Gibbs and Einstein, invented the concept of ensembles to describe equilibrium and nonequilibrium macroscopic systems. In trying to justify the use of ensembles, and to determine whether the ensembles evolved as expected from nonequilibrium to equilibrium, they introduced further concepts such as “ergodicity” and “coarse graining.” The use of these concepts raised mathematical problems that they could not solve, but like the good physicists they were they assumed that everything was or could be made all right mathematically and went on with the physics.
201 citations
TL;DR: Strain fields at Guinier-Preston zones in an (Al-3% Cu alloy crystal slice have been studied from 2-beam lattice fringe images, assuming a direct correspondence between fringe and plane displacements as discussed by the authors.
109 citations
TL;DR: In this article, the authors assess the suitability of behavioural objectives for the design of the educational process and the evaluation which would follow, and assess the relevance of the objectives to the actual educational process.
Abstract: Behavioural objectives lay the foundations for a thoroughgoing attempt to improve the effectiveness of educational systems. By specifying what the student should be able to do after the learning experience, the hope is that the outcomes of education can be brought in line with the intentions of the educator. To achieve this goal, it would be minimally necessary to ensure that the objectives were relevant, and that they could be used to prescribe fairly exactly the design of the educational process and the evaluation which would follow. The object of this paper is to assess such claims.
106 citations
TL;DR: The structure of a Cu-1.97 wt. % Be alloy crystal in the solution-treated and in the aged conditions was studied by high resolution transmission electron microscopy and electron diffraction as discussed by the authors.
98 citations
TL;DR: Palaeomagnetic data from the British Isles are reviewed and are found to be consistent with erratic polar shift from the vicinity of 10° N, 180° E in the Ordovician to 0°, 145°E in the Siluro-Devonian and to 25° n, 160° E.
Abstract: Summary
Palaeozoic palaeomagnetic data from the British Isles are reviewed and are found to be consistent with erratic polar shift from the vicinity of 10° N, 180° E in the Ordovician to 0°, 145° E in the Siluro-Devonian and to 25° N, 160° E in the early Carboniferous. The Cambrian pole is less well established near 25° N, 170° E. The rates and times of shifts are discussed.
World-wide palaeomagnetic data suggest the existence of three groups of continents in the Early and Middle Palaeozoic—the Gondwanan, Euramerican and Siberian groups—separated by large oceans which closed in the Late Palaeozoic along the lines of the Hercynides and Uralides. The data from Gondwana and Siberia are internally consistent and each may have been a single plate to which only peripheral slices were added subsequently. Data from Euramerica are less coherent. The most probable explanation seems to be that this group of continents was loosely-knit and consisted of the North American and the Baltic/Russian plates (which joined in the Silurian on the site of the Scandinavian Caledonides) and the British Isles sub-plate which joined in the Devonian (on previously unrecognized sutures lying in the present North Atlantic and North Sea respectively). This interpretation takes all the data at face value and assumes that time-coverage is adequate in all parts of the region. Alternatively, if time-coverage was not adequate, Britain might have been part of the North American plate, but further work is required to discriminate between these interpretations.
Palaeomagnetic evidence from the British Isles also indicates that little or no closure has taken place across the British Caledonides since Early Ordovician time. If so the British Isles sub-plate may have been rotated in azimuth as well as being transported laterally before joining the Euramerican plate. Examples of rotation and remagnetization on a more local scale are cited, and are ascribed to tectonic and thermal effects of orogeny respectively.
The Euramerica and Gondwana groups were already close together by early Carboniferous times, which is distinctly earlier than the Hercynian-Alleghenian orogenic belt which may mark their juncture. It may be generally true that large scale crustal drift, involving consumption of a large area of oceanic crust between two continents, significantly predates the orogenic belt which forms when the two continents have met. If this is so, large scale closure across the British Caledonides might have occurred in Precambrian or Cambrian time, but palaeomagnetic data are not yet adequate to evaluate this.
97 citations
TL;DR: The results show that certain non-specific consequences of the imprinting procedure, such as general changes in hormonal levels as a result of stress, non-visual sensory stimulation and motor activity, cannot account for the observed biochemical changes in the forebrain roof.
81 citations
TL;DR: The greater the chicks' experience on the first day, the lower the rate of incorporation of tritiated uracil into macromolecules in the anterior part of the forebrain roof on the second day.
Abstract: On the first day after hatching, domestic chicks were trained for 20, 60, 120, or 240 minutes with an imprinting stimulus. On the second day, they were all retrained for 60 minutes. The greater the chicks' experience on the first day, the lower the rate of incorporation of tritiated uracil into macromolecules in the anterior part of the forebrain roof on the second day. Such effects were not found in other brain regions, nor in any brain region of chicks that received similar treatment on the first day but were not retrained on the second.
70 citations
TL;DR: In this article, a variety of Palaeozoic rocks from four areas in the British Isles are presented for a wide range of geochemical properties, including Arenig pillow lavas at Lough Nafooey, the Cambro-Ordovician Connemara Gabbros, upper Silurian sediments of the Knocknaveen Group and Salrock Group, and intrusive rocks associated with the latter.
Abstract: Summary
Data are presented for a variety of Palaeozoic rocks from four areas in the British Isles: western Ireland (Arenig pillow lavas at Lough Nafooey, the Cambro–Ordovician Connemara Gabbros, Upper Silurian sediments of the Knocknaveen Group and Salrock Group, and intrusive rocks associated with the latter); the Ordovician of north Pembrokeshire (Trefgarn Andesitic Series, Fishguard Volcanic Series, and some basic intrusions); the Bristol District (Upper Llandovery lavas in the Tort-worth Inlier, uppermost Devonian and basal Carboniferous red sediments); and the Orkney and Shetland Islands (middle Devonian to possibly Carboniferous lavas). These provide palaeomagnetic directions of limited reliability because of restricted sampling, outcrop, or stability evidence.
Three extensions of published studies are also reported. In the Hartshill Quartzite (Cambrian) the published result has not been substantiated. The contact aureole of the Arrochar Complex (Siluro-Devonian) provides a variety of stability evidence that its remanence dates from the time of intrusion of the igneous complex. The published results from Mweelrea ignimbrites (Llanvirn) are confirmed with minor modification.
Considered with other published data, these new results suggest that the pole relative to Britain remained in the same position from early Silurian to Lower (or even Upper) Devonian time, and comparatively rapid polar shift took place both before and after this interval.
59 citations
50 citations
TL;DR: Various ways of constructing graphs whose edge-chromatic number is @r + 1 and a conjecture about such graphs are described and formulated.
TL;DR: The largest volcanic provinces of Tertiary to Recent age are located along the East African-Ethiopean-Red Sea rift system and figure prominently in modern studies of fracturing of the African plate and the development of new oceanic crust in the Red Sea.
Abstract: WITHIN the stable African plate there are several widely separated major volcanic provinces of Tertiary to Recent age. The largest of these, located along the East African-Ethiopean-Red Sea rift system are well known1,2 and figure prominently in modern studies of fracturing of the African plate and the development of new oceanic crust in the Red Sea2.
TL;DR: Aeromagnetic data, combined with other observations, support the view that some of the crust beneath the eastern Mediterranean might be oceanic, formed by seafloor spreading at a time when the Earth's magnetic field was of constant and normal polarity.
Abstract: Aeromagnetic data, combined with other observations, support the view that some of the crust beneath the eastern Mediterranean might be oceanic, formed by seafloor spreading at a time when the Earth's magnetic field was of constant and normal polarity.
TL;DR: The shield volcano Mauna Loa in Hawaii is the world's highest mountain, 9,144 m high, if the portion below sea level is considered in addition to the exposed 4,170 m as mentioned in this paper.
Abstract: THE shield volcano Mauna Loa in Hawaii is the world's highest mountain, 9,144 m high1, if the portion below sea level is considered in addition to the exposed 4,170 m. Why, then, are the world's highest mountains not land volcanoes? We have investigated the heights and volumes of land volcanoes to try to establish what factors prevent their development to heights comparable with Mauna Loa. Data on these elementary parameters are scarce. Generally, only the height of a volcano's summit above sea level is quoted, not the height above geological base level. Volumes of individual volcanoes are rarely given.
TL;DR: In this article, the authors present a theory to explain why European countries abandon colonies after the Second World War, but it does not directly refer to the end of the specific form of imperialism which concerns us here, although one may infer from Lenin's work the very general proposition that imperialism disappears when capitalism is replaced by socialism.
Abstract: Why did European countries abandon colonies after the Second World War? No acceptable theory exists to help us with this question—theory neither in the sense of conceptualizations which ‘map out the problem area and thus prepare the ground for its empirical investigation’, nor in the sense of a set of interconnected hypotheses about the specific reality of the end of colonialism which can be validated or refuted by empirical research. Lenin's classic work on imperialism develops powerful theoretical insights regarding the establishment, growth and nature of imperialism, but it does not refer directly to the end of the specific form of imperialism which concerns us here, namely colonialism, although one may infer from Lenin's work the very general proposition that imperialism disappears when capitalism is replaced by socialism. Imperialism as a consequence of capitalism is still with us today, yet colonies have been abandoned. Lenin's theory is not refuted, but at the same time it does not help us directly with an explanation for the end of colonialism.
TL;DR: This paper examined specimens from the Jebel al Abyad area in Saudi Arabia and found that the parent melt moved rapidly from depth to high level chambers where most of the chemical variation was produced by crystal fractionation.
TL;DR: An approach is described based on the application of a stochastic linear-programming formulation to a portfolio of projects, each planned using a form of the decision-tree structure called a `project tree.
Abstract: Many models of research and development (R&D) projects do not consider the intermediate outcomes and decisions that may be foreseen to arise during their evolution through the technical and commercial stages. Consideration of the sequential aspects of allocating scarce resources to a set of projects may make a great difference to the solution of the problem in terms of the optimum subset of projects to work on in the immediate future. The solution of this problem is important to R&D management. An approach is described based on the application of a stochastic linear-programming formulation to a portfolio of projects, each planned using a form of the decision-tree structure called a `project tree.' A series of elementary examples are presented as a means of gaining insight into the method. The general formulation is then presented in detail and applied to a small problem.
TL;DR: In this paper, the majority of metamorphic mica and whole-rock K-Ar ages range from 550 to 490 m.y. and are indicative of a period of post-metamorphic, epeirogenic uplift and cooling initiated in Middle Cambrian times.
Abstract: Twenty-four mineral and whole-rock K-Ar ages have been determined from twenty-two samples collected during recent mapping in northern Nigeria. With three exceptions, the samples are from narrow synclinorial belts of relatively low-grade metasedimentary rocks within the crystalline basement complex. The whole sequence is believed to have been extensively folded and metamorphosed during the Pan-African thermo-tectonic episode. No K-Ar ages older than 700 m.y. were found in the metasedimentary rocks, suggesting they may belong to the Katangan depositional cycle. The majority of metamorphic mica and whole-rock K-Ar ages range from 550 to 490 m.y. and are indicative of a period of post-metamorphic, epeirogenic uplift and cooling initiated in Middle Cambrian times. Late Cambrian deposition of molasse-type sediments in southern Ghana is believed to be the result of this uplift. A single K-Ar age of 656 m.y., obtained from a pegmatitic muscovite, suggests that metamorphic recrystallization was completed during late Precambrian times. K-Ar hornblende ages (690 to 650 m.y.) would appear to support this conclusion, but the presence of excess 40 Ar in the analyzed hornblende samples is indicated by an isochron plot.
TL;DR: Palaeomagnetic results from the'northern'Borrowdale Volcanics and from the Carrock Fell intrusive complex are reported in this article, where the mean stable remanence direction in the volcanics is D = 0", I = -46" (ag5 = 6") from 27 sites after allowing for tectonic dip.
Abstract: Summary Palaeomagnetic results are reported from the ' northern ' Borrowdale Volcanics and from the Carrock Fell intrusive complex. The mean stable remanence direction in the volcanics is D = 0", I = -46" (ag5 = 6") from 27 sites after allowing for tectonic dip. This result is supported by a decisive fold test in which precision improves by at least a factor of 3. The Carrock Fell Gabbro complex carries magnetization which is best interpreted as originating in Ordovician times when the complex was intruded as a dyke-sheet which has been subsequently only slightly warped. On this basis D = 350", I = -22", k = 11-7 from 11 sites. A corollary of this interpretation is that the 'northern' Borrowdale Volcanics were folded before the emplacement of the Carrock Fell Complex. All these data are based on partial AF demagnetization. All sites have the same polarity. The corresponding palaeomagnetic pole positions are Lat. = 7" N, Long. = 177" E, d$ = 5", dx = 8" and Lat. = 22" N, Long. = 188" E, d$ = 8", dX = 15" respectively. These are in good agreement with other British Ordovician data.
TL;DR: The plume scar or plume trace is left in the crust, as a line of volcanoes or intrusive centres as discussed by the authors, where the lithosphere happens to be moving as a result of active seafloor spreading.
Abstract: REGIONS of magmatic activity on and in the Earth's crust have long been attributed to thermal “highs”, hot spots or mantle plumes. Present doctrine1–3 holds that these plumes have a fixed abode in the upper mantle, rising through the lithosphere from time to time, to “burn” holes in the crust. If the lithosphere happens to be moving as a result of active seafloor spreading, a so-called plume scar or plume trace is left in the crust, as a line of volcanoes or intrusive centres.
TL;DR: Differential incorporation of lysine was established between exposed and control animals in two fractions of the soluble proteins and seven fractions ofthe insoluble proteins, which suggests that exposure to a new experience of this type involves a specific effect on protein synthesis, rather than a general stimulation across all fractions.
Abstract: —A resolution of the enhancement of protein synthesis in the visual cortex of rats during first exposure to light (Richardson and Rose, 1972) was achieved by polyacrylamide gel electrophoresis using a double-labelling technique. Differential incorporation of lysine was established between exposed and control animals in two fractions of the soluble proteins and seven fractions of the insoluble proteins. This suggests that exposure to a new experience of this type involves a specific effect on protein synthesis, rather than a general stimulation across all fractions.
[...]
TL;DR: In this article, the authors consider the relationship between scientific knowledge and the social context within which science is done, and propose a non-ideological and hence scientific and non-oppressive paradigm, would be a version of interactionism, dialectical materialism; such a science cannot be fully realized except in a transformed society.
TL;DR: The results are taken as suggesting that part of the protein synthesis of the visual cortex is functionally controlled, and that neuronal and neuropil fractions show a metabolic relationship which can be affected by environmental changes.
Abstract: —The rate of incorporation of [3H]lysine into acid-insoluble material in vivo was determined in neurons and neuropil from the visual cortex of dark-reared rats, littermates exposed to the light for varying lengths of time and normally reared controls. Following onset of light exposure, the elevation of incorporation was confined to the neuronal fraction. On continuous exposure for up to 96 h, the level of incorporation in the neuronal fraction dropped to that of the dark control value. In dark-reared animals, the rate of incorporation in the neuronal fraction was 68 per cent of that in neuropil, in normals it was 150 per cent. On onset of exposure, the ratio in light exposed animals approached the normal level, but on prolonged continuous exposure both light exposed and normal ratios dropped to the dark control value once more. This drop did not occur if the animals were exposed to a 12 h light/dark cycle. These results are taken as suggesting that part of the protein synthesis of the visual cortex is functionally controlled, and that neuronal and neuropil fractions show a metabolic relationship which can be affected by environmental changes. The failure to show a depression of incorporation in prolonged exposure, by comparison with earlier results under somewhat different behavioural conditions, was taken as further evidence for the ‘state-dependence’ of a number of brain biochemical parameters.
TL;DR: The results suggest that compatibility, rather than being a property of a single central channel, differs, as between the two cerebral hemispheres.
Abstract: Bimanual asymmetrical movements are generally found to be slower than symmetrical movements but asymmetrical movement normally involves visual separation of targets which might account for the effect By using a system in which the subject controls two cursors on an oscilloscope screen by moving two levers the S-R relationship on either hand can be reversed, thus providing an asymmetrical movement task without visual separation of targets Movement times for five right-handed subjects were recorded on four unimanual and six bimanual conditions varying with respect to both S-R and R-R compatibility In the unimanual conditions, the left hand was found to be as fast as the right when the opposite S-R relationship was used In the bimanual tasks visual separation of targets was a relatively minor factor movement time being strongly influenced by S-R compatibility and to a lesser degree by R-R compatibility The results suggest that compatibility, rather than being a property of a single central channel, diff
TL;DR: It is concluded that the consistent enhancement of incorporation of precursor into retinal proteins which accompanies first exposure to light is a complex response involving a number of particular protein species, rather than a general elevation.
Abstract: —Soluble and insoluble proteins from the retina of dark-reared rats and from similar rats exposed to light for the first time, were subjected to electrophoresis on polyacrylamide gels. After injection of [3H] or [14C]lysine, using a double-labelling technique, striking differences were observed in the pattern of incorporation into the forty-one fractions investigated. After exposure for 1 h significant differences emerged in 13 of these fractions (High Differential Activity fractions) when compared with incorporation in control animals, a finding which persisted, irrespective of the order of labelling. Histochemical examination for acetylcholinesterase and glycoprotein material, showed the presence of these substances in some of the high differential activity fractions, and molecular weight determination was carried out on the insoluble fractions separated on SDS-gels. It is concluded that the consistent enhancement of incorporation of precursor into retinal proteins which accompanies first exposure to light is a complex response involving a number of particular protein species, rather than a general elevation.
TL;DR: In this article, an account of a revision course given to first year science and engineering undergraduates at King's College, London, is given, where group discussion, a programmed text and various films and demonstrations were used to ensure an informal teaching situation.
Abstract: Summary The following is an account of a revision course given to first year science and engineering undergraduates at King's College, London. Group discussion, a programmed text and various films and demonstrations were used to ensure an informal teaching situation. As well as measuring student achievement by a multiple choice test, students were also asked to give their reactions to the course by filling in feedback sheets and an attitude questionnaire.
TL;DR: In this article, it is shown that the well-known expression for resolved shear stress, τ = F/A cos ⊘ cos Λ, presupposes that the crystal is a right prism, and this expression is then applicable only to regions of the crystal where the stress is uniform.
Abstract: It is recalled that the well-known expression for resolved shear stress, τ = F/A cos ⊘ cos Λ, presupposes that the crystal is a right prism. When a crystal deforms by single slip in compression, it becomes a ‘learning’ prism, and the state of stress within it becomes inhomogeneous and complex. This expression is then applicable only to regions of the crystal where the stress is uniform, and estimates are made of the limits of applicability of this equation to compression test specimens of conventional geometry.