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Showing papers by "University of Cambridge published in 1969"


Journal ArticleDOI
TL;DR: A detailed theory of cerebellar cortex is proposed whose consequence is that the cerebellum learns to perform motor skills and two forms of input—output relation are described, both consistent with the cortical theory.
Abstract: 1. A detailed theory of cerebellar cortex is proposed whose consequence is that the cerebellum learns to perform motor skills. Two forms of input-output relation are described, both consistent with the cortical theory. One is suitable for learning movements (actions), and the other for learning to maintain posture and balance (maintenance reflexes). 2. It is known that the cells of the inferior olive and the cerebellar Purkinje cells have a special one-to-one relationship induced by the climbing fibre input. For learning actions, it is assumed that: (a) each olivary cell responds to a cerebral instruction for an elemental movement. Any action has a defining representation in terms of elemental movements, and this representation has a neural expression as a sequence of firing patterns in the inferior olive; and (b) in the correct state of the nervous system, a Purkinje cell can initiate the elemental movement to which its corresponding olivary cell responds. 3. Whenever an olivary cell fires, it sends an impulse (via the climbing fibre input) to its corresponding Purkinje cell. This Purkinje cell is also exposed (via the mossy fibre input) to information about the context in which its olivary cell fired; and it is shown how, during rehearsal of an action, each Purkinje cell can learn to recognize such contexts. Later, when the action has been learnt, occurrence of the context alone is enough to fire the Purkinje cell, which then causes the next elemental movement. The action thus progresses as it did during rehearsal. 4. It is shown that an interpretation of cerebellar cortex as a structure which allows each Purkinje cell to learn a number of contexts is consistent both with the distributions of the various types of cell, and with their known excitatory or inhibitory natures. It is demonstrated that the mossy fibre-granule cell arrangement provides the required pattern discrimination capability. 5. The following predictions are made. (a) The synapses from parallel fibres to Purkinje cells are facilitated by the conjunction of presynaptic and climbing fibre (or post-synaptic) activity. Reprinted with permission of The Physiological Society, Oxford, England. (b) No other cerebellar synapses are modifiable. (c) Golgi cells are driven by the greater of the inputs from their upper and lower dendritic fields. 6. For learning maintenance reflexes, 2(a) and 2 (b) are replaced by 2’. Each olivary cell is stimulated by one or more receptors, all of whose activities are usually reduced by the results of stimulating the corresponding Purkinje cell. 7. It is shown that if (2’) is satisfied, the circuit receptor → olivary cell → Purkinje cell → effector may be regarded as a stabilizing reflex circuit which is activated by learned mossy fibre inputs. This type of reflex has been called a learned conditional reflex, and it is shown how such reflexes can solve problems of maintaining posture and balance. 8. 5(a), and either (2) or (2’) are essential to the theory: 5(b) and 5(c) are not absolutely essential, and parts of the theory could survive the disproof of either.

3,151 citations


Journal ArticleDOI
TL;DR: In this paper, it was found that an occipital evoked potential can be elicited in the human by moving a grating pattern without changing the mean light flux entering the eye.
Abstract: 1. It was found that an occipital evoked potential can be elicited in the human by moving a grating pattern without changing the mean light flux entering the eye. Prolonged viewing of a high contrast grating reduces the amplitude of the potential evoked by a low contrast grating. 2. This adaptation to a grating was studied psychophysically by determining the contrast threshold before and after adaptation. There is a temporary fivefold rise in contrast threshold after exposure to a high contrast grating of the same orientation and spatial frequency. 3. By determining the rise of threshold over a range of spatial frequency for a number of adapting frequencies it was found that the threshold elevation is limited to a spectrum of frequencies with a bandwidth of just over an octave at half amplitude, centred on the adapting frequency. 4. The amplitude of the effect and its bandwidth are very similar for adapting spatial frequencies between 3 c/deg. and 14 c/deg. At higher frequencies the bandwidth is slightly narrower. For lower adapting frequencies the peak of the effect stays at 3 c/deg. 5. These and other findings suggest that the human visual system may possess neurones selectively sensitive to spatial frequency and size. The orientational selectivity and the interocular transfer of the adaptation effect implicate the visual cortex as the site of these neurones. 6. This neural system may play an essential preliminary role in the recognition of complex images and generalization for magnification.

1,931 citations


Book ChapterDOI
TL;DR: The problem of coherence in the history of ideas can be traced back to the notion of the coherence of a moral philosophy as discussed by the authors, which was introduced in the early 20th century.
Abstract: ed from it and more readily communicated. To write a textbook in the history of ideas, of course, is simply to fall prey systematically to this temptation which, incidentally, is why textbooks in the subject are not merely poor things, but are actively misleading, and why this difficulty is not to be circumvented even by providing textbooks in which the "message" is given in the author's own words. The inevitable result which can be illustrated from far more respectable sources than the synoptic and pedagogic histories will still be a form of writing which might be labelled the mythology of coherence. The writing of the history of ethical and political philosophy is pervaded by this mythology.69 Thus if "current scholarly opinion" can see no coherence in Hooker's Laws, the moral is to look harder, for "coherence" is surely "present."70 If there is doubt about the "most central themes" of Hobbes's political philosophy, it becomes the duty of 'the exegete to discover the "inner coherence of his doctrine" by reading the Leviathan a number of times, until in a perhaps excessively revealing phrase he finds that its argument has "assumed some coherence."'7' If there is no coherent system "readily accessible" to the student of Hume's political works, the exegete's duty is "to rummage through one work after another" until the "high degree 69. A similar point about the problem of accommodating different "levels of abstraction" has been made by J. G. A. Pocock, "The History of Political Thought: A Methodological Enquiry," in Philosophy, Politics and Society, Second Series, ed. Peter Laslett and W. G. Runciman (Oxford, 1962), 183-202. This "scripturalist tendency" is also mentioned by Peter Laslett sub "Political Philosophy, History of," in The Encyclopedia of Philosophy, ed. Paul Edwards et al., 8 vols. (New York, 1967), VI, 371. 70. Arthur S. McGrade, "The Coherence of Hooker's Polity: The Books on Power," Journal of the History of Ideas 24 (1963), 163. 71. Howard Warrender, The Political Philosophy of Hobbes (Oxford, 1957), vii. This content downloaded from 157.55.39.210 on Sat, 30 Jul 2016 06:00:09 UTC All use subject to http://about.jstor.org/terms THE HISTORY OF IDEAS 17 of consistency in the whole corpus" is duly displayed (again in a rather revealing phrase) "at all costs."72 If Herder's political ideas are "rarely worked out systematically," and are to be found "scattered throughout his writings, sometimes within the most unexpected contexts," the duty of the exegete again becomes that of trying "to present these ideas in some coherent form."73 The most revealing fact about such reiterations of the scholar's task is that the metaphors habitually used are those of effort and quest; the ambition is always to "arrive" at "a unified interpretation," to "gain" a "coherent view of an author's system."74 This procedure gives the thoughts of various classic writers a coherence, and an air generally of a closed system, which they may never have attained or even been meant to attain. If it is first assumed, for example, that the business of interpreting Rousseau's thought must center on the discovery of his most "fundamental thought," it will readily cease to seem a matter of importance that he contributed over several decades to several quite different fields of enquiry.75 Again, if it is first assumed that every aspect of Hobbes's thought was designed as a contribution to the whole of his "Christian" system, it will cease to seem at all peculiar to suggest that we may turn to his autobiography to elucidate so crucial a point as the relations between ethics and political life.76 Again, if it is first assumed that even Burke never essentially contradicted himself or changed his mind, but that a "coherent moral philosophy" underlies everything he wrote, then it will cease to seem at all unrealistic to treat "the corpus of his published writings" as "a single body of thought."77 Some measure of the lengths to which such procedures of abstracting the variety of a man's thoughts to the level at which they can be said (all passion spent) to "attain" some coherence is provided by a recent study of Marx's social and political thought. Here it has seemed necessary, to justify the exclusion of Engels's thoughts, to point out that Marx and Engels were after all "two distinct human beings."78 It does sometimes happen, of course, that the aims and successes of a given writer may remain so 72. John B. Stewart, The Moral and Political Philosophy of David Hume (New York, 1963), v-vi. 73. F. M. Barnard, Herder's Social and Political Thought (Oxford, 1965), xix. Cf. also 139. 74. E.g., J. W. N. Watkins, Hobbes's System of Ideas (London, 1965), 10. 75. Ernst Cassirer, The Question of Jean Jacques Rousseau, tr. and ed. Peter Gay (Bloomington, Indiana, 1954), 46, 62. As Gay indicates in his Introduction, it may well have been salutary at the time when Cassirer was writing to have insisted on such an emphasis, but it remains questionable whether the somewhat a priori assumptions of the study are not misconceived. 76. F. C. Hood, The Divine Politics of Thomas Hobbes (Oxford, 1964), 28. 77. Charles Parkin, The Moral Basis of Burke's Political Thought (Cambridge, 1956), 2, 4. 78. Shlomo Avineri, The Social and Political Thought of Karl Marx (Cambridge, 1968), 3. This content downloaded from 157.55.39.210 on Sat, 30 Jul 2016 06:00:09 UTC All use subject to http://about.jstor.org/terms

1,400 citations


Journal ArticleDOI
TL;DR: 132 consecutive patients were investigated during the postoperative period using the 125 I-labelled fibrinogen test to detect deep-vein thrombosis in the legs to indicate which patients are at risk and which require active treatment.

830 citations


Journal ArticleDOI
02 Aug 1969-Nature
TL;DR: It is suggested that allogeneic liver can induce immunological tolerance in immunologically mature pigs and help protect donor specific tissue from rejection.
Abstract: Liver allografting experiments with pigs show that animals given no immunosuppression will survive for prolonged periods with orthotopic liver transplants. Similar animals can reject skin, kidneys and hearts rapidly. Orthotopic and accessory heterotopic liver allografts protect preferentially from rejection grafts of donor specific skin, kidney and possibly heart. Injected soluble liver antigen may also protect donor specific tissue from rejection. It is suggested that allogeneic liver can induce immunological tolerance in immunologically mature pigs.

771 citations



Journal ArticleDOI
TL;DR: In this article, a direct measurement of the forces in air between two cylindrical sheets of mica arranged with their axes mutually at right angles is made using multiple beam interferometry using fringes of equal chromatic order.
Abstract: A direct measurement has been made of the forces in air between two cylindrical sheets of mica arranged with their axes mutually at right angles. The contact resembles that between a sphere and a flat. The mica sheets are glued to glass formers, their concave face being first slightly silvered. The contact region and the distance of approach are measured by multiple beam interferometry using fringes of equal chromatic order (f. e. c. o.). This gives an accuracy for the distances between the surfaces of ± 0.3 nm. Since the surfaces are molecularly smooth it is possible to bring them very close to one another. One surface is held on a rigid support, the other on a light cantilever beam. The surfaces are slowly brought together and at a critical separation ‘flick’ together. The ‘flick’ distance depends on the stiffness of the cantilever and this in turn provides a direct measure of the surface forces. By using cantilevers of different stiffnesses the method has proved effective for separations ranging from 5 to 30 nm. The results show that for separations less than about 10 nm the forces operating are ‘normal’ van der Waals forces whilst for distances greater than 20 nm they are ‘retarded’ van der Waals forces.

668 citations


Journal ArticleDOI
01 Oct 1969-Nature
TL;DR: The simple geometric ideas of plate theory are extended to include some forms of plate evolution as discussed by the authors The most important of these occurs where three plates meet such triple junctions are divided into two groups, stable and unstable, according to whether or not they can retain their geometry as the plates move.
Abstract: The simple geometric ideas of plate theory are extended to include some forms of plate evolution The most important of these occurs where three plates meet Such triple junctions are divided into two groups, stable and unstable, according to whether or not they can retain their geometry as the plates move These ideas suggest an explanation for some of the major changes which have occurred in the North Pacific during the Tertiary

596 citations


Journal ArticleDOI
15 Feb 1969-Nature
TL;DR: Human oocytes have been matured and fertilization by spermatozoa in vitro and there may be certain clinical and scientific uses for human eggs fertilized by this procedure.
Abstract: Human oocytes have been matured and fertilized by spermatozoa in vitro. There may be certain clinical and scientific uses for human eggs fertilized by this procedure.

480 citations


Journal ArticleDOI
TL;DR: The records of 554 consecutive patients attending hospitals in the Cambridge region with urticaria have been analysed with the aid of a computer and in 79%, the aetiology was unknown although in many cases aggravating factors, for example, psychological stress, aspirin, or infection, were detected.
Abstract: SUMMARY.— The records of 554 consecutive patients attending hospitals in the Cambridge region with urticaria have been analysed with the aid of a computer. These patients represent only a small minority of all patients with urticaria in the region. In 79%, the aetiology was unknown although in many cases aggravating factors, for example, psychological stress, aspirin, or infection, were detected. A past or family history of atopic disorders was not found more frequently in patients with urticaria than in controls and the course of the disease in patients with a background of atopy did not differ from the remainder, suggesting that an undetected allergy is not responsible for many of these undiagnosed cases. Allergy is relatively more important in acute urticaria and in patients who do not attend hospital. The frequency of attacks and total duration of the disease are different in patients with urticaria alone, angio-oedema alone and both together but there was little difference in the aetiological factors, supporting the concept that urticaria and angio-oedema are fundamentally similar. The prognosis is expressed in the form of life tables.

459 citations


Journal ArticleDOI
TL;DR: In this article, the effect of continuous convection from small sources of buoyancy on the properties of the environment when the region of interest is bounded is considered, assuming that the entrainment into the turbulent buoyant region is at a rate proportional to the local mean upward velocity, and that the buoyant elements spread out at the top of the region and become part of the non-turbulent environment at that level.
Abstract: This paper considers the effect of continuous convection from small sources of buoyancy on the properties of the environment when the region of interest is bounded. The main assumptions are that the entrainment into the turbulent buoyant region is at a rate proportional to the local mean upward velocity, and that the buoyant elements spread out at the top of the region and become part of the non-turbulent environment at that level. Asymptotic solutions, valid at large times, are obtained for the cases of plumes from point and line sources and also periodically released thermals. These all have the properties that the environment is stably stratified, with the density profile fixed in shape, changing at a uniform rate in time at all levels, and everywhere descending (with ascending buoyant elements).The analysis is carried out in detail for the point source in an environment of constant cross-section. Laboratory experiments have been conducted for this case, and these verify the major predictions of the theory. It is then shown how the method can be extended to include more realistic starting conditions for the convection, and a general shape of bounded environment. Finally, the model is applied quantitatively to a variety of problems in engineering, the atmosphere and the ocean, and the limitations on its use are discussed.

Journal ArticleDOI
TL;DR: In this paper, it is shown that a thin layer of liquid (the microlayer) forms beneath the vapour bubble, which can also be deduced from a simple theory for the hydrodynamics of the formation of the layer.

Journal ArticleDOI
TL;DR: In this article, it was shown that if sea level during the Holocene was higher than at present, as Daly also supposed, the effects on reef features would be profound, and that oceanic reefs developed by progressive subsidence of their foundations.
Abstract: Summary 1. The classical ‘coral reef problem’ concerned the geological relationships of reefs as major topographical features; modern coral studies consider reefs both as complex biological systems of high productivity and as geological structures forming a framework for and being modified by coral growth. 2. Deep borings in reefs have conclusively confirmed the general arguments of Darwin, that oceanic reefs developed by progressive subsidence of their foundations. Darwin failed to take account of Pleistocene changes in sea level and their effect on the present surface features of reefs. Daly's alternative ‘glacial control theory’ was based on false assumptions concerning marine erosion rates during glacial periods, but if sea level during the Holocene was higher than at present, as Daly also supposed, the effects on reef features would be profound. 3. Reefs are complex biological systems in tropical seas, dominated by scleractinian corals. Coral faunas are larger and more diverse in the Indo-Pacific than in the Atlantic. Hermatypic corals are restricted to shallow water by the light requirements of their symbiotic algae, but temperature is a major control of worldwide distributions. Temperature, salinity and sediment tolerances of corals are wider than formerly supposed, and corals can survive brief emersion except when it coincides with heavy rainfall. Water turbulence is an important ecological control, but difficult to measure. 4. The trophic status of corals is still unclear, but in spite of their anatomical and physiological specialization as carnivores it is likely that they derive some nutrient substances from zooxanthellae. Suggestions that filamentous algae in coral heads play a major part in the economy of the corals have not been supported by later work, but biomass pyramids constructed on the basis by Odum and Odum remain the only ones available. Most reefs are apparently autotrophic, with 1500–3500 g. Carbon being fixed per m.2 per year. 5. Few animals eat corals, which may account for their success. Important predators are fish and the echinoderm Acanthaster. Quantitative estimates of biogenic erosion of organic skeletons on reefs are high. Fish affect not only corals but other invertebrates, algae and marine phanerogams. 6. Corals may be killed by ‘dark water’, intense rain or river floodwaters, earth movements, human interference and especially hurricanes. Reef recovery after hurricanes may take 10–20 years. 7. In addition to fringing, barrier and atoll reefs, intermediate types are recognised. The main types may consist of linear reefs or faros. Smaller lagoon reefs include pinnacles, patches and platforms, and submerged knolls. Complex cellular or mesh reef patterns are also found. 8. Reefs are conspicuously zoned, both laterally in response to changing exposure to waves to form windward and leeward reefs, and transversely, as a result of steep environmental gradients across reef flats from sea to lagoon. Topographic and ecological zones may be characterized by particular coral species, but these vary widely from reef to reef. A major distinction can be made between reefs with and without algal ridges, which are common on open-ocean trade-wind reefs, in the Indo-Pacific, but are absent on Caribbean reefs and on Indo-Pacific reefs in more sheltered waters. gorgonians are common on Caribbean reefs, alcyonaceans in the Indo-Pacific. 9. Much of the difficulty in comparing reefs stems from the lack of uniformity in surveying methods. Problems of describing the complex three-dimensional patterns of organisms on reefs have yet to be solved, and hence little progress has been made in explanation of these patterns. Explanation in terms of simple environmental controls is inadequate. 10. Understanding the distribution of corals is made more difficult both by taxo-nomic problems and by the plasticity of growth form in different situations. 11. Growth of corals and reefs may be estimated by measuring the growth of individual colonies, measuring rates of calcium carbonate deposition in the skeleton, measuring topographic change on the reef and deducing net rates of reef growth from geological evidence. Massive corals may increase in diameter by 1 cm./year, branches of branching corals may increase in length by 10 cm./year. Study of deposition rates shows variation within colonies, between species, in light and dark, and seasonally. Rates of reef growth extrapolated from colony measurements reach 2–5 cm./year, and contrast with figures as low as 0–02 cm/year averaged over 70 million years from borehole data. Both colony growth rates and geological data suggest worldwide variations in rates of reef growth. 12. In spite of clear evidence of long-continued subsidence, present surface features of reefs, often only thinly veneered by modern corals, have been much affected by recent sea level fluctuations. Many slightly raised reefs at 2–10 m. above sea level date at 90–160 thousand years B.P.; there is evidence for a sea level at about the present level at 30–35 thousand years B.P.; and controversy continues over whether sea level has stood higher than the present at any time since the last sea level rise began about 20,000 years ago. Evidence from many reefs suggests a slightly higher sea level in the last 4000 years, but on other reefs such evidence is lacking. 13. Several reef features (submerged terraces, groove-spur systems, algal ridge, reef flat, reef blocks and reef islands) have been interpreted either as relict features dating from a higher sea level in the last 5000 years, or contemporary features developed in response to present processes. In some cases the evidence is equivocal; in others it is clear that diverse features are being grouped together under the same name. If such features are referable to a higher sea level, this may have been of last Interglacial or even Interstadial age rather than Holocene. 14. A reef consists of a rigid framework defining several major depositional environments within and around it. Sediments are of biological, mainly skeletal origin, except in unusual environments such as the Bahama Banks. The characteristics of sediments derived from organisms depend partly on the breakdown patterns of particular skeletons, partly on transportation and sorting processes. Fine sediments may be either detrital, or physicochemical precipitates. 15. Organisms affect sediments after deposition, by disturbance, transportation and probably comminution. Fish and holothurians have been studied in detail. 16. While new theories of coral reefs are proposed from time to time, the need is less for new theories than for standardised procedures to ensure comparability of reef studies and the identification of variations in reefs both on local and regional scales. While reefs as biological systems adjust relatively rapidly to changes, reefs as geological systems adjust much more slowly. Because of the magnitude and recency of Pleistocene fluctuations in sea level, many biological features of reefs are out of phase with inherited geological features, and this had led to much controversy.

Journal ArticleDOI
12 Apr 1969-Nature
TL;DR: In this paper, the structure of the Appalachian/Caledonian orogen is described and a new model for its evolution is proposed, which is based on the model proposed in this paper.
Abstract: The structure of the Appalachian/Caledonian orogen is described and a new model for its evolution proposed.

Journal ArticleDOI
TL;DR: In this paper, skin friction and mean-velocity profiles have been made in fully developed flows in pipes and channels in the Reynolds number range 1000 < Re < 10000, and observations of hot-wire signals indicate rather remarkable differences between two-dimensional and axially symmetric flows and also make it difficult to give a precise definition of the term "fully developed turbulent flow".
Abstract: Measurements of skin friction and mean-velocity profiles have been made in fully developed flows in pipes and channels in the Reynolds number range 1000 < Re < 10000 These measurements, and observations of hot-wire signals, indicate rather remarkable differences between two-dimensional and axially symmetric flows and also make it difficult to give a precise definition of the term ‘fully developed turbulent flow’

Journal ArticleDOI
TL;DR: X-ray fibre diffraction patterns of the Pf 1 species of virus at 4°C, oriented in a strong magnetic field, give three-dimensional data to 4 A resolution, and an electron density map calculated from native virus and a single iodine derivative, shows a helix pitch of 5.9 A.
Abstract: The filamentous bacterial virus is a simple and well-characterized model system for studying how genetic information is transformed into molecular machines. The viral DNA is a single-stranded circle coding for about 10 proteins. The major viral coat protein is largely α-helical, with about 46 amino acid residues. Several thousand identical copies of this protein in a helical array form a hollow cylindrical tube 1–2μ long, of outer diameter 60 A and inner diameter 20 A, with the twisted circular DNA extending down the core of the tube. Before assembly, the viral coat protein spans the cell membrane, and assembly involves extrusion of the coat from the membrane. X-ray fibre diffraction patterns of the Pf 1 species of virus at 4°C, oriented in a strong magnetic field, give three-dimensional data to 4 A resolution. An electron density map calculated from native virus and a single iodine derivative, using the maximum entropy technique, shows a helix pitch of 5.9 A. This may indicate a stretched A-helix, or it may indicate a partially 310 helix conformation, resulting from the fact that the coat protein is an integral membrane protein before assembly, and is still in the hydrophobic environment of other coat proteins after assembly.

Journal ArticleDOI
TL;DR: A fractionation and analytical procedure is described for the measurement of the unavailable carbohydrates in foods and from the results obtained it is possible to derive values for the composition of the cell-wall material of these foods.
Abstract: A fractionation and analytical procedure is described for the measurement of the unavailable carbohydrates in foods The scheme provides values for water-soluble polysaccharides, hemicellulose, cellulose and lignin Tests used to investigate the reliability of the methods are reported and the results obtained with a range of foodstuffs are presented From the results obtained it is possible to derive values for the composition of the cell-wall material of these foods The results are in agreement with more detailed studies of the composition of the cell walls of plants

Journal ArticleDOI
TL;DR: In this article, the thermohaline stability problem was examined in greater detail, and the most unstable mode over all wave-numbers for each R, Rs was found and it was shown that where both unstable direct and oscillating modes are present, the most stable mode is direct in most cases.
Abstract: The thermohaline stability problem previously treated by Stern, Walin and Veronis is examined in greater detail. An error in an earlier paper is corrected and some new calculations made. It is shown, for instance, that direct convection can occur for thermal Rayleigh number R much less than 100 Rs when Rs [gsim ] 0·1, where Rs is the salinity Rayleigh number. A graphical presentation is devised to show the relative importance of the different terms in the equations of motion as a function of R and Rs. The most unstable mode over all wave-numbers for each R, Rs is found and it is shown that where both unstable direct and oscillating modes are present, the most unstable mode is direct in most cases.

Journal ArticleDOI
10 Oct 1969-Science
TL;DR: If, after prolonged observation of a striped pattern, one views a grating of the same orientation with somewhat narrower bars, then the bars seem even thinner than in fact they are, which implies a system of size-detecting channels in humnan vision.
Abstract: If, after prolonged observation of a striped pattern, one views a grating of the same orientation with somewhat narrower bars, then the bars seem even thinner than in fact they are. Broader bars seem broader still. This finding implies a system of size-detecting channels in humnan vision. The phenomenon may underlie many of the classical figural aftereffects.

Journal ArticleDOI
TL;DR: In this article, the authors have no associated abstract for their paper, but they fix it (fix it) by using the following abstracts from the abstracts of the paper:
Abstract: This article has no associated abstract. (fix it)


Book
01 Jan 1969
TL;DR: This chapter attempts to gather some of the threads of physiological and chemical theory underlying the practice of handling meat, with special consideration of the problem of ripening.
Abstract: Publisher Summary This chapter attempts to gather some of the threads of physiological and chemical theory underlying the practice of handling meat, with special consideration of the problem of ripening. It is found that there is a necessary preponderance of the space devoted to the discussion of physiological and chemical facts over that devoted to consideration of the opportunities that have been taken or can be suggested for the application of the facts. There are two points to which concentration of interest have been directed. The first is the vital role that the pH of flesh plays in every phase of meat technology. This general principle affords a useful plane to which the complicated events that take place in muscle post-mortem can be related, and upon which they can be oriented. The second focal point to which particular attention is drawn is the technique of evaluation of quality by panel judgments based on sensory tests.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the posterior distribution of a random sample of size n from a distribution having a density depending on a real parameter 0, and 0 having an absolutely continuous prior distribution with density ir(G) was asymptotically normal with mean equal to the maximum likelihood estimator and variance equal to a reciprocal of the second derivative of the logarithm of the likelihood function evaluated at the maximum-likelihood estimator.
Abstract: SUMMARY Let a random sample of size n be taken from a distribution having a density depending on a real parameter 0, and let 0 have an absolutely continuous prior distribution with density ir(G). We give a rigorous proof that, under suitable regularity conditions, the posterior distribution of 0 will, when n tends to infinity, be asymptotically normal with mean equal to the maximumlikelihood estimator and variance equal to the reciprocal of the second derivative of the logarithm of the likelihood function evaluated at the maximum-likelihood estimator, independently of the form of 7r(G).

Journal ArticleDOI
TL;DR: In this paper, it was shown that even if the climatic optimum of the stage had been climatically suitable for glaciation to commence in North America and Europe, ice could not have accumulated sufficiently fast to change the isotopic composition of the oceans enough to account for the observed change.
Abstract: On examination of the palaeotemperature succession obtained by Emiliani, particularly in relation to the details of last interglacial isotope stage 5, it is found that the highest palaeotemperature is always recorded early in the stage, and that this peak is followed by a sharp drop in palaeotemperature. It is shown that this palaeotemperature decline is so rapid that even if the climatic optimum of the stage had been climatically suitable for glaciation to commence in North America and Europe, ice could not have accumulated sufficiently fast to change the isotopic composition of the oceans enough to account for the observed change. It is concluded that the change was due to a drop in world temperature. Comparison with the Eemian vegetational succession shows that there is no place for such a substantial temperature decline until the end of the Eemian stage. Thus the Eemian interglacial stage corresponds to only a small part of the isotope stage 5. The age of the Eemian is considered and a value of near 120 000 years (120 ka) is found to fit the available data best. On the basis of this figure, the duration of the Eemian may be estimated from the marine record at about 11 ka. The temperature drop demonstrated comprises a fall to near the lowest glacial level. This temperature decline must have been controlled by a mechanism which did not require the presence of large ice sheets for its effect. The minor glaciation which ensued was likewise terminated by a climatic change which took effect despite the fact that continental ice sheets were by no means fully extended. These conclusions have important bearing on the theory of Pleistocene glaciations.

Journal ArticleDOI
TL;DR: In this paper, the authors describe the effects of this instability on the formation of a depression in the surface when the load is concentrated into a few small parts of the surface causing high local temperatures.
Abstract: If two sliding solids are nominally in contact over a large area, the inevitable irregularities in the surfaces will cause the pressure distribution to be non-uniform. The generation of heat due to friction at the interface will also be non-uniform and the solids will be distorted by thermal expansion. The highest parts of the surface will carry the greatest pressure, reach the highest temperature and consequently expand more than the surroundings. Thus the thermal distortion tends to exaggerate the initial irregularity of the surface. The wear at the interface has the opposite effect, but under suitable conditions the process can be unstable. Experiments are described in which the effects of this instability are observed: the load is concentrated into a few small parts of the surface causing high local temperatures. After a few seconds, the load is transferred to a new part of the surface and, when the original contact area has returned to the temperature of the surroundings, it contracts leaving an observable depression in the surface. The scale of this process is large in comparison with the size of the surface asperities. An experimental model has been produced which demonstrates the characteristics of the instability in a simplified form. The thermal expansion drives the surfaces apart at the beginning of the cycle and this movement has been observed experimentally. An analysis of the instability is produced and a good correlation is obtained with experiment.

Journal ArticleDOI
TL;DR: In this article, it was shown that when the relay control system consists of a pure integrators, with n ≥ 3, and the control signal proceding the relay is a linear combination of state coordinates, the system is unstable in the large for all values of the controller coefficients.
Abstract: It is shown that when the plant of a relay control system consists of a pure integrators, with n ≥ 3, and the control signal proceding the relay is a linear combination of state coordinates, the system is unstable in-the-large for all values of the controller coefficients. The same result holds if the relay is replaced by a. saturator. The method used is to prove that (except for a degenerate case) state trajectories exist which go to infinity. This method enables more general systems to be treated than those discussed in a previous paper, which demonstrated the existence of a periodic solution. Plants not consisting of pure integrators are also considered. The question of when it is worthwhile to incorporate non-linearities in the controller is discussed.


Journal ArticleDOI
TL;DR: Two modifications to the formulation are discussed, one of which takes account of possible tremor effects, and the other of the possibility that visual control when ‘homing’ on a target may be slower than the control of movement designed to cover a given distance.

Journal ArticleDOI
08 Feb 1969-Nature
TL;DR: In this paper, it was suggested that the depletion of noradrenaline produced by 6-hydroxydopamine might be a result of damage to the amine storage sites in sympathetic nerves in a manner similar to that of reserpine.
Abstract: THE compound 6-hydroxydopamine (2,4,5-trihydroxyphenylethylamine) produces a long lasting depletion of noradrenaline (NA) from peripheral sympathetically innervated tissues in various species1,2. It was originally suggested that the depletion of noradrenaline produced by 6-hydroxydopamine might be a result of damage to the amine storage sites in sympathetic nerves in a manner similar to that of reserpine, or that, alternatively, 6-hydroxydopamine might act as a “false transmitter” and displace noradrenaline from sympathetic nerves1–4. Electron microscopy has shown recently, however, that after treatment with 6-hydroxydopamine the terminal regions of peripheral adrenergic nerves degenerate and eventually disappear5. The noradrenaline depletion produced by 6-hydroxydopamine has been suggested to result from this acute degeneration of adrenergic terminals. This hypothesis was supported by the histochemical evidence that after treatment with 6-hydroxydopamine the fluorescent network of sympathetic nerve terminals in the rat iris disappeared, while the fluorescence of preterminal axons increased6. 6-Hydroxydopamine thus induces changes similar to those seen after section of an adrenergic nerve, suggesting that this compound produces a “chemical sympathectomy”5.

Journal ArticleDOI
TL;DR: Brain slices were incubated with [3H]GABA in a medium containing aminooxyacetic acid to prevent metabolism of [3h)GABA by GABA‐glutamate transaminase and the efflux from the tissue was measured.
Abstract: — Brain slices were incubated with [3H]GABA in a medium containing aminooxyacetic acid to prevent metabolism of [3H]GABA by GABA-glutamate transaminase. The slices, which rapidly accumulated radioactivity, were then continuously perfused and the efflux of [3H]GABA from the tissue was measured. The spontaneous efflux of [3H]GABA consisted of an initial rapid phase followed by a much slower release of [3[H]GABA. After 40 min perfusion 90 per cent of the radioactivity remained in the tissue. The slices were depolarized by electrical stimulation or by perfusion with a medium containing a high potassium concentration (40 mM). These procedures caused a striking increase in the efflux of [3H]GABA. The increased efflux produced by potassium, but not that produced by electrical stimulation, was dependent on calcium ions in the medium. The effect of electrical stimulation on [3H]GABA release was considerably reduced by a raised concentration (10 mM) of magnesium in the medium. High potassium concentrations and electrical stimulation did not cause an increase in the efflux of [14C]urea, L-[3H]leucine or [14C]α-amino-isobutyric acid from brain slices. These results are consistent with the suggestion that GABA may be an inhibitory transmitter in the cerebral cortex.