Showing papers by "Cardiff University published in 1980"
TL;DR: A new model is proposed that deals with the explanation of cases in which learning does not occur in spite of the fact that the conditioned stimulus is a signal for the reinforcer by specifying that certain procedures cause a conditioned stimulus to lose effectiveness.
Abstract: Several formal models of excitatory classical conditioning are reviewed. It is suggested that a central problem for all of them is the explanation of cases in which learning does not occur in spite of the fact that the conditioned stimulus is a signal for the reinforcer. We propose a new model that deals with this problem by specifying that certain procedures cause a conditioned stimulus (CS) to lose effectiveness; in particular, we argue that a CS will lose associability when its consequences are accurately predicted. In contrast to other current models, the effectiveness of the reinforcer remains constant throughout conditioning. The second part of the article presents a reformulation of the nature of the learning produced by inhibitory-conditioning procedures and a discussion of the way in which such learning can be accommodated within the model outlined for excitatory learning.
2,779 citations
TL;DR: It is concluded that Candida is not uniformly distributed throughout the mouth but that the tongue is the primary oral reservoir for the fungus, from which the rest of the oral mucosa, plaque-coated surfaces of the teeth and the saliva may become secondarily colonized in a proportion of carriers.
489 citations
TL;DR: The aim of the study was to explore the extent to which deviant dental features may expose children to ridicule and embarrassment and it appeared that for teasing in particular, dental features could provide a significant target for abuse.
Abstract: The aim of the study was to explore the extent to which deviant dental features may expose children to ridicule and embarrassment. In the first part of the study, 531 school children were interviewed about their experience of nicknaming, teasing and harassment and it appeared that for teasing in particular, dental features could provide a significant target for abuse. The findings were also related to a teacher's brief assessment of the child's personality.In the second part of the investigation, the salience of dental features to children was examined by asking 82 children to respond to a cine film showing 12 children's faces and it appeared that in general, the more deviant the dental arrangement, the more salient will it be. In discussion however, it is considered that many other characteristics of an individual child will influence not only the abuse which he may attract but also the nature of his response.
249 citations
228 citations
TL;DR: The relationship between malocclusion and the health of the masticatory apparatus is reviewed and there is no evidence that children with visible irregulaities will in general be emotionally handicapped and the need for further research is underlined.
Abstract: The relationship between malocclusion and the health of the masticatory apparatus is reviewed. While there is evidence that certain features such as traumatic deep overbite, unprotected incisors and impacted teeth may adversely affect the longevity of the dentition, the relationship of dental irregularity to periodontal disease, caries and mandibular dysfunction is less certain. Studies in the field of social psychology indicate that an unattractive physical appearance may evoke an unfavourable social response in many facets of social interaction but the place of dentofacial anomalies in this context has not been satisfactorily assessed. The individual's adjustment to his own imperfections in dental alignment is variable and there is no evidence that children with visible irregulaities will in general be emotionally handicapped. Effectiveness studies have yet to be undertaken but the factors which will have to be taken into account in assessing the benefits of orthodontic treatment are the definition of treatment need, treatment standards, the disadvantages of treatment and the influence of other determinants of dental health. The need for further research is underlined.
191 citations
TL;DR: C1(2)MDP seems to be an effective oral drug for inhibiting excessive bone resorption in man and reduced plasma-calcium and urinary calcium in patients with hypercalcaemia due to primary hyperparathyroidism or secondary to malignant disease.
178 citations
TL;DR: Nominal Group Technique is a structured method of group decision‐making which allows a rich generation of original ideas, balanced participation of all members of the group, and a rank‐ordered set of decisions based on a mathematical voting method.
Abstract: Committee-work which involves decision-making from a range of alternatives is frequently time-consuming, inefficient, and frustrating. Nominal Group Technique is a structured method of group decision-making which allows a rich generation of original ideas, balanced participation of all members of the group, and a rank-ordered set of decisions based on a mathematical voting method. A brief description of a Nominal Group Technique session is given and its application to decision-making by committees of anaesthetists is illustrated by an example.
150 citations
TL;DR: Combined analysis of the HLA-DRw3 status and the level of thyrotrophin-receptor antibody at the time of drug withdrawal relapse or remission could be predicted in 62 of the 65 patients with hyperthyroid Graves' disease.
140 citations
126 citations
TL;DR: A mechanism for the rapid oxidation of sulphide to thiosulphate was shown to be present in rat liver mitochondria and, in the presence of glutathione, the thiosULphatewas oxidized to sulphate.
119 citations
TL;DR: The physical and mechanical properties of a range of higher strength polymers developed for use in dentistry to overcome the strength deficiencies of polymethylmethacrylate (PMMA) are reviewed.
TL;DR: Compared 2 existing techniques with a new one and with a modification of a little-used technique for determining the rate of cell loss from the stratum corneum, there was a strong positive correlation between the "chamber" technique and the "scrub" technique (measuring forced desquamation).
TL;DR: For a minimum of 30 months, 250 women who underwent mastectomy for primary breast cancer have been followed up, finding that in patients with node involvement ER‐positive (ER+) tumors carry a better prognosis.
Abstract: The prognostic value of estrogen receptor measurements (ER) in primary breast tumors is assessed in this report. Also ER analysis of primary breast tumor specimens was examined with respect to responses of the secondary disease to endocrine therapy and to cytotoxic therapy. 250 women mastectimized for primary breast cancer were followed up for at least 30 months. When recurrence was diagnosed endocrine ablation or cytotoxic chemotherapy was administered. ER status seemed to have a pronounced effect on disease-free interval and on subsequent survival. Based on lymph node biopsies assayed at mastectomy patients with node involvement and ER positive tumors have a better prognosis. 43% of patients with ER positive primary tumors had objective response to their secondary diseases for at least 6 months whereas only 18% of ER negative tumor patients had objective responses to secondaries. Patients with previous endocrine therapy (ER positive) who were treated on relapse with cytotoxic chemotherapy showed objective response rate to chemotherapy far superior to patients with ER negative tumors; this result was not statistically significant however.
TL;DR: In this article, a central, low pressure vapour-droplet mixture is described, which is conceived to be retained within an ice shell, and providing a potentially hospitable environment for elementary life forms.
Abstract: Comets accreted soon after the initial collapse and cooling of the solar nebula, and containing a plausible fraction of 26Al, would have been significantly heated as this radionuclide decayed. Snow-and-dust balls as described by integrals of the heat conduction equation would melt in the centre if larger than 3–6 km radius. A central, low pressure vapour-droplet mixture is described here, which is conceived to be retained within an ice shell, and providing a potentially hospitable environment for elementary life forms. Refreezing after some million years produces a partially-hollow core.
TL;DR: In this article, the role of chemisorbed oxygen in inducing the formation of hydroxyl species on a Cu(111)-O surface has been confirmed by selective reduction of a mixed oxy-hydroxide adlayer by CO.
TL;DR: The earliest record of a fossil flora containing Cooksonia type sporangia was from a mid-Ludlow (Silurian) locality in Wales as discussed by the authors, which was collected in the Devilsbit Mountain district of County Tipperary, Ireland.
Abstract: Hitherto the earliest record of a fossil flora containing Cooksonia type sporangia was from a mid-Ludlow (Silurian) locality in Wales1. The compression fossils illustrated here (Figs 1–4) come from strata assigned to the highest graptolite zone of the Wenlock Series characterized by Monograptus ludensis. They were collected (by J. F.) in the Devilsbit Mountain district of County Tipperary, Ireland. But this is not just a record of the first appearance of a genus which extends to the end of the Lower Devonian, because Cooksonia has generally been accepted as a vascular plant2. Its occurrence at the top of the Wenlock therefore seems to extend the history of vascular plants back to the middle of the Silurian and to indicate that higher plants colonized land surfaces at least 415 Myr ago.
TL;DR: In this article, eight 14C dates were obtained from a 5 cm thick Ah, horizon of a podzol soil buried in situ beneath the outermost end moraine of the Haugabreen gletscherfeld, southern Norway.
Abstract: Eight 14C dates have been obtained from a 5 cm thick Ah, horizon of a podzol soil buried in situ beneath the outermost end moraine of the Haugabreen gletschervorfeld, southern Norway. The dates ran...
TL;DR: A sensitive RIA has been developed for assay of testosterone in male saliva and extensively validated, and morning concentrations were significantly higher than evening samples, and the circadian rhythm was confirmed by COSINOR analysis.
Abstract: A sensitive RIA (500 fg/tube) has been developed for assay of testosterone in male saliva and extensively validated. In normal male saliva samples, morning concentrations (368 +/- 167 pmol/l) were significantly higher than evening samples (212 +/- 132 pmol/l). The circadian rhythm was confirmed by COSINOR analysis. Levels of testosterone in saliva, in response to HCG stimulation, accurately reflected the increase observed in matched plasma samples. Synacthen administration, although increasing circulating cortisol levels, caused no significant change in plasma and salivary testosterone concentrations. Prostatic cancer patients on diethylstilboestrol therapy had low salivary (47--122 pmol/l) and plasma (1.0--2.8 nmol/l) testosterone concentrations. Correct assessment of testicular function following stimulation and treatment regimens requires multiple sampling. Since saliva samples are easily collected by non-invasive techniques they represent an attractive alternative to plasma for evaluation of androgenicity.
TL;DR: Results suggest that the secretion of glycosylated ferritin from rcticuloendothelial cells reaches a maximum with increasing iron accumulation, perhaps reflecting a maximum rate of synthesis.
Abstract: Serum ferritin concentrations have been measured in 124 patients with homozygous beta thalassaemia who were between 2 and 21 years old, had received 11--504 units of blood but had not undergone splenectomy. There were highly significant correlations between serum ferritin concentration and both the amount of blood transfused and alanine amino-transferase (ALT) activity. However, multivariate analysis showed that units of blood and ALT activity together only accounted for about 30% of the variation in serum ferritin concentration. Little of the remaining variation could be explained by other variables related to iron metabolism or liver damage. The concentration of concanavalin A binding ferritin increased rapidly with the number of units of blood up to 100 units but thereafter showed no further increase with number of transfusions. The concentration of non-binding ferritin was more closely related to transfusion load. These results suggest that the secretion of glycosylated ferritin from reticuloendothelial cells reaches a maximum with increasing iron accumulation, perhaps reflecting a maximum rate of synthesis. Ferritinaemia in patients with transfusional iron overload therefore seems to be the result of the combined effects of increased ferritin synthesis and the release of intracellular ferritin from damaged cells. A simple relationship between serum ferritin and iron stores cannot be assumed when ferritin concentrations exceed 4000 microgram/l or in patients who have received more than 100 units of transfused blood.
TL;DR: It is concluded that the dry skin condition of patients with atopic eczema is not autosomal dominant ichthyosis and is probably eczematous in nature.
Abstract: SUMMARY
The non-eczematous but ‘dry’ skin of twelve patients with eczema has been studied and contrasted with skin from similar sites in control subjects of similar age and sex and with patients with autosomal dominant ichthyosis. The areas investigated were examined histologically and by techniques for assessment of the stratum corneum structure and function. The ‘dry’ skin sites demonstrated increased intracorneal cohesion, increased total epidermal thickness, patchy parakeratosis and in places slight hypergranulosis. It is concluded that the dry skin condition of patients with atopic eczema is not autosomal dominant ichthyosis and is probably eczematous in nature.
TL;DR: It is concluded that the use of the term biotype in this species is biologically misleading and undesirable.
Abstract: From previous studies, the biological nature of the so-called biotypes of N. lugens is obscure. Experiments on biotypes 1, 2 and 3 from the Philippines demonstrated that they lacked significant breeding barriers. Inbred biotype cultures showed considerable variation and overlap between each other in virulence. A field population from the Philippines was similarly variable and included individuals which could be attributed to different biotypes. It is concluded that the use of the term biotype in this species is biologically misleading and undesirable.
RESUME
LES “BIOTYPES” DE NILAPARVATA LUGENS (STAL)
La nature biologique de ce qui a ete appele des biotypes de Nilaparvata lugens, parait obscure si l'on se refere aux etudes anterieures. Des experiences sur les biotypes 1, 2 et 3 des Philippines revelent qu'ils ne presentent pas de barrieres sexuelles significatives. Les elevages consanguins de biotypes presentent une variabilite considerable, et les virulances des biotypes se chevauchent les unes les autres. De meme une population recoltee dans les champs aux Philippines etait heterogene et comprenait des individus qui auraient pu etre rattaches a differents biotypes. On peut en conclure que le terme de biotype est, pour cette espece, inapproprie et indesirable.
TL;DR: Examiniation of purified heart, kidney, liver and spleen ferritin showed that the assay was highly specific for acidic isoferritins, suggesting a radioimmunoassay for acidic ferrtin purified from HeLa cells may be of value in the diagnosis of malignancy.
TL;DR: A seasonal cycle in byssal attachment strength of Mytilus edulis is described in a population of mussels on the South Wales coast and suggested that the resulting decline in reserves is accentuated by the need for greater byssus production at this time to secure the mussels against the rigours of autumn and winter storms.
Abstract: A seasonal cycle in byssal attachment strength of Mytilus edulis is described in a population of mussels on the South Wales coast. Attachment strength reaches a maximum in September with a minimum in May.INTRODUCTIONMany seasonal cycles of a physiological nature have been described in the common mussel Mytilus edulis L. (reviewed by Gabbott, 1976; also Pieters et al. 1978; Zurburg et al. 1978), some of which, for example the annual accumulation and subsequent utilization of energy substrates, appear to be linked to gametogenesis. Following spawning in the spring the gonads of Mytilus enter a resting phase; metabolic demands are low. Glycogen and protein are accumulated in the tissues at this time as phytoplankton is abundant. Gonadal development commences in autumn when phytoplankton density has declined and energy is supplied by the utilization of stored reserves. Pieters et al. (1978) have suggested that the resulting decline in reserves is accentuated by the need for greater byssus production at this time to secure the mussels against the rigours of autumn and winter storms. No accounts exist of field studies which might support this hypothesis.
TL;DR: The presence of copper during growth of Aureobasidium pullulans in both liquid and solid media had a profound effect on morphology of the organism and promoted formation of filaments or hyphae during later stages of growth.
Abstract: The presence of copper during growth of Aureobasidium pullulans in both liquid and solid media had a profound effect on morphology of the organism. In addition to stimulating melanin synthesis copper also promoted formation of filaments or hyphae during later stages of growth. The taxonomic implications of these findings are discussed.
TL;DR: In this paper, the micromorphology of two soil profiles developed on turf-banked solifluction lobes and a third profile formed on a larger turf-banked terrace is described.
TL;DR: The Sporadhes basin is an asymmetrical graben closely similar to Gulf Coast structures (down-to-basin faults) that have been modelled experimentally by Cloos (1968).
TL;DR: Follow-up of patients with possible angina but normal coronary arteriograms suggests that coronary artery spasm or other causes of myocardial ischaemia are rare in these patients.
Abstract: Follow-up of patients with possible angina but normal coronary arteriograms suggests that coronary artery spasm or other causes of myocardial ischaemia are rare in these patients. Oesophageal spasm proved a common cause of diagnostic difficulty.