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Biomedical subjects

A Blake

Publications and source records attributed to A Blake.

At least 55 records · Page 3Linked to original sources
PubMed1990

Does the brain know the physics of specular reflection?

Images of artificial and natural scenes typically contain many highlights generated by mirror-like reflection from glossy surfaces. Until recently, computational models of visual processes have tended to regard highlights as obscuring the structure of the underlying scene. The truth is that, on the contrary, highlights are rich in local geometric information. Here we report that the three-dimensional appearance of a highlight on a computer-simulated stereoscopic curved surface affects observers' judgment of surface gloss. We also show that the 3-D appearance of a highlight affects the perception of surface curvature--that is, it can force an ambiguous convex-concave figure to change state. We thus conclude that human visual analysis seems to employ a physical model of the interaction of light with curved surfaces, a model firmly based on ray optics and differential geometry.

Brain↗
PubMed1990

Diet and coronary heart disease risk factors in a population with varied intake. The Research Group ATS-RF2 of The Italian National Research Council.

The relationship between consumption of foods high in saturated fats and cholesterol and a number of coronary heart disease risk factors (blood pressure, serum glucose, serum cholesterol, and triglycerides) was analyzed in a large sample (4,917) of Italian men and women, ages 20-59 years. The dietary habits of the participants were ascertained with a food frequency questionnaire. Intake of atherogenic foods (foods high in cholesterol and saturated fats) was evaluated for each participant. In both sexes, systolic blood pressure, serum glucose, and serum cholesterol increased with higher consumption of atherogenic foods. These findings were independent of any possible confounding effect of age, adiposity, alcohol intake, and cigarette smoking. The present article confirms previous findings that consumption of foods high in saturated fats and cholesterol is associated with an increased risk for atherosclerosis.

Adult↗
PubMed1988

Pathophysiological sequelae of hepatic artery ligation: an experimental study.

The effects of ligation of the proper hepatic artery were studied in 40 rats. The serum transaminase and bilirubin levels were elevated significantly at 24 h following surgery but had returned to normal by the 7th postoperative day. The serum albumin level was significantly reduced at 24 h and remained low for a further 2 weeks. There was no histological abnormality in the liver following hepatic artery ligation. It would appear that there is an early return to normal function following hepatic artery ligation.

Animals↗
PubMed1985

Effect of beta-blockers on psychomotor performance in normal volunteers.

The effects of beta-adrenergic receptor antagonists on psychometric tests including vehicle handling, choice reaction time, and kinetic visual acuity (KVA), are reviewed. The beta-blockers had little effect on the performance tests, with the unexplained but reproducible effect of enhanced KVA performance with atenolol. Although the beta-blockers had little effect on performance tests they were shown to have psychotropic effects in normal volunteers. The reasons for the conflicting evidence concerning the effect of these drugs on performance tests is discussed in relation to the present experiments and to variables that may influence response. It is concluded that one should use tests that are as independent as possible from potentially confounding variables. The use of evoked potentials in the electroencephalogram is one such test. A preliminary study is described in which the effects of beta-blockers were detected using visual evoked responses on the electroencephalogram.

Adolescent↗
PubMed1976

Group approach to weight control: behavior modification, nutrition, and health education.

We have had a positive experience using a modified approach to behavior modification of eating patterns, exercise, and activity, along with nutrition and health education. During the first year, forty-four adult patients completed the program, which was conducted in the out-patient clinic of a large hospital by a dietitian and a nurse practitioner. A cross-section of the patient population was admitted. The program had a pre-determined number of sessions, each of which was partially structured. When compared with the patients in individual therapy in our Nutrition Clinic, a more consistent weight loss in a shorter time was observed in the group participants. Whether the techniques described here will lead to sustained weight loss over time bears further study.

Adult↗
PubMed1975

Parents of babies of very low birth weight: long-term follow-up.

On hundred and sixty babies of birth weight less than or equal to 1500 g who survived after perinatal intensive care have been followed up and observations have been made on their parents. In spite of attempts to minimize maternal separation and the distressing aspects of the birth and management of a baby of very low birth weight, an emotional crisis was observed in the mothers which was not fully resolved until the parents had been looking after the baby at home. The duration and degree of the crisis varied but the mothers who received sympathy and support from the baby's father appeared to have least difficulty. A rigid maternal personality and circumstances surrounding the birth which predisposed to feelings of failure and guilt appeared to prolong the crisis. Nevertheless, most of these parents subsequently formed satisfactory relationships with their children, although they tended to be over-protective and anxious. Failure to establish an adequate relationship was rare and occurred only among mothers with personality or psychiatric disorders. Although serious behaviour disorders among the children were rare, more children than would be expected were mildly over-dependent, shy and anxious at follow-up.

Birth Weight↗
PubMed1967

Physical and chemical reactions of phosphates in red cell membranes in relation to active transport.

1. A study has been made of the chemical reactions associated with the active transport of sodium and potassium in human red cells, with special reference to the action of oligomycin and the labelling of cell membranes by radioactive ATP.2. Oligomycin had the same effects as ouabain on the various aspects of active transport in red cells. It inhibited sodium and potassium transport, the transport ATPase, and the lactate production that is controlled by the sodium pump.3. When cell membranes were incubated with radioactive ATP they became labelled. The labelling, however, was unrelated to the activity of the transport ATPase. Incubation of membranes and intact cells showed that the labelling was a result of physical adsorption of inorganic phosphate to the membranes.4. The results show that if there is a phosphate intermediate in the reaction of the transport ATPase in human red cell membranes, then it is present in amounts too small to be detectable by the methods that have been successfully used with organs such as brain and kidney.

Adenosine Triphosphatases↗