Showing papers by "University of Sussex published in 1971"
[...]
TL;DR: It is argued that at least two types of description of the pattern must be utilised if any significant pattern generalisation is to be achieved, and in general that all picture interpretation tasks involve descriptions in two domains.
686 citations
[...]
TL;DR: It is suggested that the most important advantage of sex arises when two genetically different populations migrate into a new environment, in which the best adapted genotype is a combination of genes from the two invading populations.
421 citations
TL;DR: The ease of obtaining quiet-biting attack by stimulation of the hypothalamus thus seems to interact with the endogenous disposition of rats to kill mice.
256 citations
210 citations
TL;DR: The requirements for intelligent decision-making proposed by McCarthy and Hayes are criticised as too narrow, and more general requirements are suggested instead.
192 citations
TL;DR: The authors showed that the results of several recent studies of categorization may be interpreted in terms of conjoint frequency (the frequency of cooccurrence of a category and instance in English).
149 citations
TL;DR: Home-cage mouse-killing and reflexive-fighting were studied in rats before and after medial and lateral hypothalamic lesions, finding failure to find differential lesion effects on the different modes of aggression evidence that relatively nonspecific facilitatory and inhibitory influences from the lateral hypothalamus and medial hypothalamus modulate both predatory aggression and reflexives.
143 citations
139 citations
TL;DR: The formation of the hypostome and the regeneration of distal structures, and the establishment and maintenance of the axial gradients in Hydra are studied.
Abstract: (I) An outline of the problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111. The axial pattern in Hydra . . . . . . . . . . . . . . . . . . . (2) The formation of the hypostome and the regeneration of distal structures (3) The formation of the basal disk . . . . . . . . (4) Polarity and the establishment and maintenance of the axial gradients . ( 5 ) The initiation and individuation of the bud . . . . . . IV. The individuation of the hydranth of Tubularia . . . . . . . (I) General principles . . . . . . . . . . . V. Theoretical models for the formation and regulation of axial patterns . (2) ‘Positional information’ models . . . . . . . . (3) Inhibition and induction models VI. Discussion . . . . . . . . . . . . VII. Summary . . . . . . . . . . . . VIII. References . . . . . . . . . . . . . . . . . . . .
123 citations
TL;DR: The Posnefs method of using differences in RT for physical and name matches to estimate the time constant of visual STM is criticized as confounding the decay of the visual trace with the development of a name code.
Abstract: Posnefs method of using differences in RT for physical and name matches to estimate the time constant of visual STM is criticized as confounding the decay of the visual trace with the development of a name code When this confounding is avoided by using stimuli that are hard to name (a 5 by 5 matrix of randomly filled squares), the time constant shown by both RT and errors is consistently longer than that reported by Posner
110 citations
TL;DR: In this paper, the effect of carbon fiber/polyester composites on fracture toughness and interlaminar shear strength was investigated by means of Charpy V-notch impact tests and slow three-point bend tests on notched specimens of triangular cross-section.
Abstract: Fracturing of carbon fibre/polyester composites has been studied by means of mechanical testing and scanning electron microscopy. Carbon fibres were surface-treated in several ways so as to vary the interlaminar shear strength of the composites, and the effect of this variation on the work of fracture was determined by means of Charpy V-notch impact tests and slow three-point bend tests on notched specimens of triangular cross-section. The effect of moisture on the fracture toughness was also studied by measuring toughness and interlaminar shear strength after exposure to steam. Improvement of the fibre/resin bond results, as expected, in an increase in the brittleness of composites and it appears that a purely mechanical bond, such as might be obtained by acid-etching the fibre surface, is less proof against deterioration in humid atmospheres than a chemical bond, such as can be obtained by the use of coupling agents. Estimates of the magnitude of various contributions to the fracture toughness show that in carbon-fibre-reinforced resins the effect of increasing the stiffness or load-bearing ability of the matrix and the work done against friction in pulling broken fibres out of the matrix contribute approximately one fifth and four fifths, respectively, of the total work of fracture.
TL;DR: It was demonstrated that substitution at the glycine-A1 amino group by the larger residues, acetoacetyl or thiazolidinecarbonyl, produced a decrease in biological activity, while modification of the lysine-B29 or phenylalanine- B1 amino groups with these larger reagents did not affect the biological activity.
Abstract: The acetylation of the free amino groups of insulin was studied by reaction of the hormone with N-hydroxysuccinimide acetate at pH6.9 and 8.5. The products formed were separated by chromatography on DEAE-Sephadex and were characterized by isoelectric focusing, by end-group analysis, by the incorporation of [3H]acetyl groups in the molecule, and by treatment with trypsin that had been treated with 1-chloro-4-phenyl-3-toluene-p-sulphonamidobutan-2-one (`tosylphenylalanyl chloromethyl ketone'). Three monosubstituted products, two disubstituted products and one trisubstituted derivative were prepared. The α-amino groups of the terminal residues and the -amino group of the lysine-B29 were the sites of reaction. Acetylation of any of the free amino groups did not affect the biological activity of insulin. It was demonstrated, however, that substitution at the glycine-A1 amino group by the larger residues, acetoacetyl or thiazolidinecarbonyl, produced a decrease in biological activity. Modification of the lysine-B29 or phenylalanine-B1 amino groups with these larger reagents did not affect the biological activity. Modification of the phenylalanine-B1 amino group by any of the three substituents resulted in a large decrease in the affinity of insulin for anti-insulin antibodies raised in the guinea pig. Modification of the other two amino groups did not affect the reaction with antibody. These observations are correlated with the tertiary structure of insulin.
TL;DR: The study of biological nitrogen fixation at the genetic level has been restricted by the lack of a suitable method of gene transfer in nitrogen-fixing bacteria as mentioned in this paper, but the transfer and mapping of the nitrogen fixation genes have not so far been possible.
Abstract: THE study of biological nitrogen fixation at the genetic level has been restricted by the lack of a suitable method of gene transfer in nitrogen-fixing bacteria. Mutants of Azotobacter vinelandii1,2 and Clostridium pasteurianum3 defective in nitrogen fixation have been isolated and characterized, but the transfer and mapping of the nitrogen fixation (nif) genes have not so far been possible.
TL;DR: In this article, it was suggested that the Peterson technique comprises two components, a primary memory component which decays within 6 seconds, and a more stable secondary memory component, which is attributed to the need to use temporal retrieval cues to avoid confusion between successive items.
Abstract: It has been claimed that the short-term forgetting shown by the Peterson technique is entirely due to proactive interference from prior experimental items. Two experiments investigated this by studying forgetting when prior items were avoided by testing subjects only once. Both experiments showed significant forgetting, although the degree of forgetting was less than with a multitrial procedure. On the basis of this and other results it is suggested that the Peterson technique comprises two components, a primary memory component which decays within 6 sec, and a more stable secondary memory component. Forgetting with the multitrial procedure is attributed principally to the need to use temporal retrieval cues to avoid confusion between successive items; longer retention intervals are associated with reduced temporal discriminability and hence poorer recall.
TL;DR: In this article, the authors bring together experimental results which have yielded some quantitative information with respect to the anisotropy of conduction electron scattering in the noble metals and find that from the ordinary transport properties, and in particular from analyses of the Hall effect and deviations from Mattheissen's rule, the assembled conclusions do not present a coherent picture, at least with regard to electron impurity scattering.
Abstract: The main purpose of this paper is to bring together experimental results which have yielded some quantitative information with respect to the anisotropy of conduction electron scattering in the noble metals. It is found that from the ordinary transport properties, and in particular from analyses of the Hall effect and deviations from Mattheissen's rule, the assembled conclusions do not present a coherent picture, at least with regard to electron-impurity scattering. The results for scattering by phonons are more consistent. The advent recently of rather precise (∼ 0·1%) specifications of the noble metal Fermi surfaces together with the knowledge of certain derivative properties over them makes possible more direct measurements of electron scattering. The application of experimental techniques which are more commonly associated with the field of ‘Fermiology’, and in particular the de Haas-van Alphen effect, to study conduction electron scattering more directly is an important theme of the present ...
TL;DR: The corpora pedunculata, or mushroom bodies, are paired lobes of neuropile present in the protocerebrum or dorsal brain of all insects and are divisible into three parts: calyx, stalk and roots.
Abstract: The corpora pedunculata, or mushroom bodies, are paired lobes of neuropile present in the protocerebrum or dorsal brain of all insects. They are divisible into three parts: calyx, stalk and roots. The latter usually comprise two simple lobes, the a and ft lobes. The corpora pedunculata of a variety of Lepidoptera were examined. All had a double calyx-cup. Each ‘cup-cavity’ is composed of ‘globuli’ cell bodies. The broad stalk, a tract of fibres and neuropile, leads from the calyx to the complex ‘roots’—a, g and y lobes. A third group of globuli cells near the calyx gives rise to a tract leading to a second lobe-system—the tripartite Y-lobe—in the roots. As neither the Y tract nor the Y lobe has been described before in any insect, their possible homologues are unknown. The two lobe systems in the roots are closely intertwined, yet have no interaction except in the y lobe. A number of different neuron types with branches in the mushroom bodies has been described from Golgi preparations. Some (intrinsic cells) divide in the calyx and again in the roots, but do not pass out of the mushroom bodies. Others (extrinsic cells) branch in the mushroom bodies and in other areas of the brain, thus connecting two regions. Intrinsic cells arise from cell bodies in the calyx-cups or posterior to them. There are two types: one has extensive spine-covered branches in the calyx, while the second has claw-like terminals covering a narrow cylindrical field. Processes from these cells run to the a, j>and y lobes via the stalk. A wide-field accessory cell, which arises from the third group of globuli cell bodies, also has claw-like endings in the calyx. A process of this cell runs in the Y-tract to the Y-lobe. Extrinsic terminals in the calyx arise from cells branching in the antennal lobe, in an accessory optic area in the protocerebrum, in the ‘undifferentiated’ protocerebral neuropile, or in the suboesophageal lobes. The antennal terminals in the calyx are knob-like. It is proposed that they form the centre of the ‘glomeruli’ typically present in calycal neuropile. The claws of the bunched intrinsic and accessory cells probably fit around these knobs. Within the stalk, different subvarieties of intrinsic cells have been distinguished on the basis of the distribution of the side-branches and spines which they bear. The stalk is thought to be the site of extensive postsynaptic interaction between intrinsic cells. Fibres in the stalk run in bundles or groups. All the fibres in one bundle are of the same subvariety. In the roots, the subvarieties of intrinsic cells have different branching patterns. The a and B lobes are not homogeneous, but are divided into sublobes. Extrinsic fibres ramify only within one sublobe generally, though some have very large fields. The connexions of the roots are obscure. Some extrinsic fibres branch again in the ‘undifferentiated’ protocerebral neuropile; others, from the B lobe, may run to the suboesophageal lobes. There are profound differences between the internal organization of the mushroom bodies in Hymenoptera (Kenyon 1896; Goll 1967) and Lepidoptera. The functional implications of the Lepidopteran form are discussed.
TL;DR: In this paper, the photoelectron bands associated with ionization from the formally non-bonding p orbitals of the halogen atoms in the halomethanes have been interpreted in terms of a pseudo one-electron hamiltonian.
Abstract: The photoelectron bands associated with ionization from the formally non-bonding p orbitals of the halogen atoms in the halomethanes have been interpreted in terms of a pseudo one-electron hamiltonian. Account has been taken of interactions between the halogen atoms, of interactions between the halogen p orbitals and the σ-bonding orbitals, and of spin-orbit coupling. This model leads to a systematic assignment of all the bands of the chloro and bromomethanes, and gives a satisfactory account of the spin-orbit splittings in the bromomethanes.
TL;DR: In this article, a balanced mixture of amino acids followed by access to protein-free food having a distinctive odour was given to rats and the preference was acquired whether the duration of odour presentation, or the amount of odouredised food taken, was kept constant on the two conditioning days.
Abstract: Protein-deprived rats were given, on one day, a balanced mixture of amino acids followed by access to protein-free food having a distinctive odour. On another day, an imbalanced (histidine-free) amino acid mixture was given just before food having another odour. The rats afterwards preferred the balance-paired odour to the imbalance-paired odour. The preference was acquired whether the duration of odour presentation, or the amount of odourised food taken, was kept constant on the two conditioning days. Retention of the preference seemed unattenuated after 4 weeks. An attraction to the balance-paired odour (relative to odours paired with a water load) contributed to the acquired preference. There was also a relative aversion to unfamiliar odours when they had been paired with imbalance. Such acquired chemosensory control of preferences, together with an anorexigenic effect of imbalanced amino acid mixtures, can account for characteristics of feeding behaviour under conditions in which the diet is deficient...
TL;DR: A class of directionally selective movement detector recorded in the visual system of the privet hawk-moth seems designed in several respects to enable the moth to track a moving target.
Abstract: A CLASS of directionally selective movement detector1 recorded in the visual system of the privet hawk-moth seems designed in several respects to enable the moth to track a moving target. Although I have found no behavioural evidence that these moths can follow moving objects, the properties of the neurones will be described in the context of visual tracking, because similar neurones may be involved in the control of smooth-tracking eye movements in vertebrates.
TL;DR: Rats with lesions in the ventromedial hypothalamus—the so-called satiety-center—exhibited normal depressions in food intake after stomach loads of all three macronutrients: fats, proteins and carbohydrates, suggesting that the hypothalamic satieties-center probably does not mediate post-prandial inhibition of feeding.
TL;DR: Investigation of the properties of the inactive ribosomes of resting lymphocytes has shown that, unlike those of stimulated cells, they do not become attached to polyribosomes when protein synthesis is partially inhibited by cycloheximide, but are capable of attaching to the synthetic messenger RNA poly(U).
TL;DR: In this article, the authors present an experimental method for determining the variation of the local heat transfer coefficient around gas turbine blades, which involves the accurate determination of the distillation coefficient of the turbine blades.
Abstract: This paper presents an experimental method for determining the variation of the local heat transfer coefficient around gas turbine blades. The method involves the accurate determination of the dist...
TL;DR: In this article, a high cone density was found to be characteristic of amorphous (mechanically polished) surfaces whilst a low cone density with height contrast of the individual grains was discovered on polycrystalline (etched) surfaces.
Abstract: Argon and xenon bombardment of gold surfaces at 5 to 20 keV resulted in considerable erosion and the formation of cones. A high cone density was found to be characteristic of amorphous (mechanically polished) surfaces whilst a low cone density with height contrast of the individual grains was discovered on polycrystalline (etched) surfaces. The cone angles were found to vary only slowly with energy, indicating an ion/atom potential that varied much more rapidly with separation than predicted by using a screened coulomb potential.
TL;DR: Since VMH lesioned animals no longer exhibit the normal behavior energizing effects of food-deprivation, such unusual aspects of the VMH feeding syndrome as finickiness and motivational inertia can be understood to be natural consequences of the neural mechanisms underlying feeding.
TL;DR: The mass spectra of the series of compounds Me 3 MM′Me 3 and Me 4 M are reported and analyzed in this article, where M and Mt are C, Si, Ge, Sn, and Pb.
TL;DR: In this article, the authors investigate the existence and uniqueness of a class of similarity solutions of an equation which arises in the study of fluid flow through porous media, and propose a method to solve it.
Abstract: : The authors investigate the existence and uniqueness of a class of similarity solutions of an equation which arises in the study of fluid flow through porous media.
TL;DR: A new analytical method for calculating crack density distributions from Hertzian fracture data is presented in this paper, which is the first correct analysis to be reported within the limitations of the assumptions made and is also one which can be readily applied.
Abstract: A new analytical method for calculating crack density distributions from Hertzian fracture data is presented This is the first correct analysis to be reported within the limitations of the assumptions made and is also one which can be readily applied Results are presented for a piece of polished pure silica glass and their statistical significance is discussed
TL;DR: Ornithine decarboxylase activity in rat hepatoma cells in suspension culture declines progressively with increasing cell density and is barely detectable in stationary phase, high-density cultures, suggesting that, at least under some circumstances, the synthesis of this enzyme is under post-transcriptional control.
TL;DR: It is concluded that mutation induction after UV (in uvr + strains) or after γ-radiation, at least at some loci, can occur before the first DNA replication and need not involve recombination between homologous chromosomes, despite a dependence upon the recA + allele.
Abstract: Loss of photoreversibility of mutations to streptomycin resistance occurred in the absence of DNA replication in a uvr + but not in a uvrA strain of Escherichia coli WP2 after exposure to UV, suggesting that excision may be the first step in the mutational process at this locus. A similar result was obtained with bacteria grown in a chemostat under conditions where most of the genes were unreplicated within a given cell. Such bacteria were also almost as mutable by γ-radiation as logarithmic-phase bacteria with several genomes. It is concluded that mutation induction after UV (in uvr + strains) or after γ-radiation, at least at some loci, can occur before the first DNA replication and need not involve recombination between homologous chromosomes, despite a dependence upon the recA + allele.
TL;DR: An epidemiological study has been made of rates of mental illness in a number of ethnic minorities who are immigrants to Britain, and have settled in a defined area of South London, finding that those from Africa, the Old Commonwealth, India and Pakistan have the highest rates.
Abstract: An epidemiological study has been made of rates of mental illness in a number of ethnic minorities who are immigrants to Britain, and have settled in a defined area of South London. Of the groups considered, those from Africa, the Old Commonwealth, India and Pakistan have the highest rates. The lowest rates were found in those from Cyprus and Malta, native Britons, and those from the Caribbean. After controlling for the effects of age, sex and social class it was found that the pattern of illness in a number of the immigrant groups differed from the pattern found in the native born. Those from Africa, the Caribbean and India and Pakistan manifested an excess of schizophrenia, while those from Eire manifested a dearth of such illness when compared with matched, native-born controls. The combination of the following factors was used to try to predict the rank order of illness rates among the ethnic groups considered: community integration; status isolation; status striving in a climate of limited opportunity; and selective migration.