Biomedical subjects
Publications and source records attributed to R Lynn.
Children's intelligence increased in the United States by approximately 3 IQ points per decade over the period 1932-78. New evidence shows that these increases have been sustained during the last 20 years. Two recent studies indicate that the rates of increase for 1972-89 and 1978-89 were 3.3 and 3.5 IQ points per decade, respectively.
Numerous studies in the United States have shown that mean test scores between Blacks and Whites differ by about one standard deviation. It has further been noted that the magnitudes of these differences vary on different tests. This variation can be explained by Spearman's hypothesis, which states that Black-White differences on a set of cognitive tests are positively associated with the tests' g loadings (the general intellectual ability). The present study, conducted among Black, Indian, and White secondary students in South Africa, showed mean Black-White differences of two standard deviations, indicating that the American results of one standard deviation are not universally correct. With regard to Spearman's hypothesis, it was found that, although the mean White-Indian differences were about one standard deviation, these differences did not support the hypothesis. Results pertaining to the Black-White differences were ambiguous; the correlation of .62 (p < .05) between the Black g and the Black-White differences strongly supported the hypothesis. A nonsignificant correlation of .23 was obtained between the White g and the Black-White differences. Possible reasons for this finding are discussed.
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Unaccustomed eccentric exercise, in which a muscle is lengthened while generating tension, is well known to cause injury and pain. A rapid training effect has been demonstrated in a number of eccentric exercises. The mechanism for both the damage and the training has been unknown. Morgan proposed that the damage is caused by sarcomere length instabilities during operation on the descending limb of the sarcomere length-tension curve and that the training effect is an increase in the number of sarcomeres connected in series in a muscle fiber, thus avoiding the descending limb (Biophys. J. 57: 209-221, 1990). We tested this proposal by exercising rats on a treadmill set at either an incline or a decline of 16 degrees, an exercise that has previously been shown to cause damage in untrained rats and a training effect. The vastus intermedius muscles were fixed and were digested in acid, and the fiber and sarcomere lengths of representative fibers were measured. From these measurements, the mean number of sarcomeres per fiber was found for the different training regimes. A clear and repeatable difference was found, supporting Morgan's prediction of more sarcomeres after decline running, although with some differences in response that depended on the age of the rats.
Sex differences are reported for samples of approximately 1000 16-year-old blacks, Indians and whites in South Africa on ten tests of cognitive ability. Males obtained significantly higher means on non-verbal reasoning, spatial and mechanical aptitude, and females obtained significantly higher means on perceptual speed and memory for meaning (except among the black sample). In general the sex differences in South Africa are consistent with those typically obtained in the United States.
Peters' claim that there is no association between brain size and IQ is incorrect. Numerous studies show that there is a statistically significant correlation between the two.
In this study we compared reaction times broken down into decision times and movement times between 9-year-old British and Korean boys and girls. Boys tended to be faster on movement times, but there was no sex difference in decision times. These results were obtained on three reaction-time tasks of different levels of complexity.
The Wechsler Adult Intelligence Scale-Revised (WAIS-R) has been adapted with minor revisions for use in China and standardized on a sample of 179 adults. Sex differences on the subtests are similar to those in the United States, with women obtaining higher means on the Digit Symbol subtest and men obtaining higher means on the Information and Arithmetic subtests. Men obtained higher verbal, performance, and full-scale IQs in China. The factor structure of the Chinese WAIS-R also is similar to those obtained on the Wechsler tests in the United States and Scotland.
Sex differences in competitiveness, the valuation of money, and the importance attached to saving money were examined among university students in 20 countries, using questionnaires. In general, the men obtained higher mean scores than the women did. Scores on the trait questionnaires were generally positively intercorrelated, suggesting the presence of a single trait underlying the sex difference.
PURPOSE: Provision of lifelong angioaccess for hemodialysis generally requires multiple procedures. To extend the availability of each extremity as an access site, we have used the transposed basilic vein for fistula construction since 1988. Our purpose is to present our initial experience, with follow-up of 30 months. METHODS: We have used the transposed proximal basilic vein in 65 procedures to construct an autogenous arteriovenous fistula (AVF) to the brachial artery in 58 patients without suitable superficial venous anatomy. There were 25 males and 33 females, with a mean age of 47 years (range 10 to 77). The basilic vein transposition was the initial angioaccess procedure in only 25% of cases and secondary in 75%. Three additional patients underwent exploration of an inadequate basilic vein with subsequent prosthetic grafting. RESULTS: There were no operative deaths. Two postoperative complications included a wound infection and a transient steal syndrome. The actuarial life-table patency rate for all successfully completed AVFs was 49% at 30 months. Late revisions with continued patency were required in 11 cases, including repair of a focal stenosis in six, pseudoaneurysm resection in two, and thrombectomy in one. Sixty-seven percent of patients who required subsequent prosthetic grafting for a failed basilic vein AVF had an ipsilateral procedure. Patient preference for the opposite arm was the usual indication for contralateral grafting in the remainder. CONCLUSIONS: The transposed basilic vein AVF was technically feasible in 95% of cases, can frequently be performed in patients with multiple previous access procedures, does not compromise the arm for future prosthetic grafting, and has a long-term patency rate that is comparable to more traditional autologous AVFs. This underused procedure should be considered before placement of polytetrafluoroethylene graft for long-term angioaccess.
The British Paediatric Surveillance Unit is a joint undertaking of the British Paediatric Association, the PHLS Communicable Disease Surveillance Centre and the Department of Epidemiology at the Institute of Child Health, London. It provides an active case reporting system which aims to facilitate the surveillance of rare childhood infections and other conditions. Cards with a menu of up to twelve reportable disorders are sent monthly to more than 1100 paediatricians throughout the United Kingdom and Ireland. The average response rate is 90%. Reported cases are followed up according to study protocols. Since its inception in 1986, the Unit has facilitated the study of a wide range of disorders, including HIV infection and AIDS, Reye's syndrome, Kawasaki disease, congenital rubella, neonatal herpes, congenital toxoplasmosis and acute rheumatic fever, and the number of new applications for surveys has increased in 1992-3. Several European paediatric organisations have expressed interest in setting up similar schemes in their own countries.
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Nine-year-old Korean children (N = 299) were tested for reaction time (RT) and intelligence measured by Raven's Standard Progressive Matrices. Reaction times were broken into decision times and movement times and into three degrees of complexity. The results showed low but generally statistically significant correlations between decision times and intelligence. Generally, no significant differences existed between movement times and intelligence. Boys showed significantly faster movement times than girls did.
Thirty-three tournament-level young Belgian chess players aged 8 to 13 were tested with the French WISC (Wechsler Intelligence Scale for Children). The mean full scale IQ = 121, verbal IQ = 109 and performance IQ = 129. The results suggest that a high level of general intelligence and of spatial ability are necessary to achieve a high standard of play in chess. The high spatial ability of these young chess players suggested by the high performance IQs may go some way towards explaining why males tend to be more numerous than females among high-standard chess players.
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Japanese and British 9-year-old children were compared on the standard progressive matrices and twelve reaction time parameters providing measures of simple and complex decision times, movement times and variabilities. The mean of the Japanese children on the progressive matrices exceeded that of the British children by 0.65 SD units and on the decision times component of reaction times by 0.50 SD units, suggesting that the high Japanese mean on psychometric intelligence is largely explicable in terms of the more efficient processing of information at the neurological level. Japanese children also showed faster movement times but, contrary to expectation, had greater variabilities than British children.
Sleep disorders, including a high incidence of sleep apnea, have been recognized as a significant problem in chronic renal failure (CRF) patients. In a preliminary study, we examined CRF patients on maintenance hemodialysis for three nights; one control night, and thereafter randomized to infusion of saline (placebo) for one night and 4% branch-chain amino acid (BCAA) solution for one night. Polysomnographic and respiratory data [respiratory rate, oxygen saturation and end-tidal CO2 (ETCO2)] was recorded continuously throughout the nights and data from each hour compared with baseline (awake) values. The patients studied were characterized by reduced sleep quality and decreased amount of rapid eye movement (REM) sleep. The BCAA infusion was associated with a return of REM sleep to normal and a significant decrease in ETCO2 during both REM and non-REM sleep (P less than 0.05). Our findings demonstrate respiratory stimulation during sleep with infusion of BCAA; this stimulatory effect on respiration (in contrast to many respiratory stimulants) is associated with an increased amount of REM sleep.