Changes in insulation of wetsuits during repetitive exposure to pressure.

This investigation was intended to a) establish a relationship between pressure and thickness (and hence insulation) of wetsuits during acute changes in pressure from 0.5 to 5 atmospheres absolute (ATA); b) determine the effect of repetitive compression-decompression (C-D) procedures on the insulation properties of wetsuits; and c) assess the possible recovery of insulation after cessation of repetitive C-D. Various wetsuits with different thicknesses and types of linings were selected.

Changes in limb volume during head-out water immersion in humans.

In order to investigate the contribution of fluid shift from the legs to immersion-induced diuresis, 7 normal and 2 legless (both legs disarticulated at the hip) individuals were tested to measure changes in leg volume (normal subjects) and urinary excretion of solutes and water during a 3-h head-out water immersion (HOI) in thermoneutral water (34.5 +/- 0.5 degrees C) with a 1-h control period before and after immersion.

Crew workload in JASDF C-1 transport flight: II. Change in urinary catecholamine excretion.

Serial changes in urinary catecholamine excretion were determined for 17 cockpit crews (6 captains, 6 copilots and 5 flight engineers) of JASDF C-1 aircraft during 10-hour (h) scheduled flights, in which captains and copilots performed almost the same flight tasks. The norepinephrine/epinephrine ratio (N/E) in copilots decreased significantly during the flight, whereas little decrease of the N/E was found in captains. Flight engineers showed an intermediate N/E value between captains and copilots.

Independence of brain and tympanic temperatures in an unanesthetized human.

Temperature within the brain and the esophagus and at the tympanum were obtained in a 12-yr-old male in a series of experiments that began 8 days after surgery for implantation of a drainage catheter. Fanning the face did reduce tympanic temperature but not temperature in the brain; brain temperatures followed esophageal temperatures. In long-term monitoring, temperature in the lateral ventricle was 0.

Critical water temperature during water immersion at various atmospheric pressures.

The present work was undertaken to determine the effect of atmospheric pressure [ranging from a high altitude of 4,300 m above sea level or 0.6 atmospheres absolute (ATA) to depths of 10 m deep or 2 ATA] on the critical water temperature (Tcw), defined as the lowest water temperature a subject can tolerate at rest for 2 h without shivering, of the unprotected subject during water immersion. Nine healthy males wearing only shorts were subjected to immersion to the neck in water at 0.

Renal and endocrine responses in the elderly during head-out water immersion.

After overnight food and fluid restriction, seven healthy old (62-74 yr) and eight young (21-28 yr) men were examined before, during, and after 3-h head-out immersion (HOI) in thermoneutral water (34.5 +/- 0.5 degrees C).

Effect of pressure on thermal insulation in humans wearing wet suits.

The present work was undertaken to determine the critical water temperature (Tcw), defined as the lowest water temperature a subject can tolerate at rest for 3 h without shivering, of wet-suited subjects during water immersion at different ambient pressures. Nine healthy males wearing neoprene wet suits (5 mm thick) were subjected to immersion to the neck in water at 1, 2, and 2.5 ATA while resting for 3 h.

Modification of a conventional bicycle ergometer for underwater use.

With a few simple modifications, a conventional row-bicycle ergometer could be made suitable for underwater use. By attaching three sizes of fins to the pedal cranks of the ergometer, work load in water could be achieved to an oxygen consumption (VO2) level range of 400 to 2000 ml/min. The preferable range of pedaling speeds was 30-40 rpm to maintain a constant speed for a prolonged time.

Statistical properties of molecular tree construction methods under the neutral mutation model.

The statistical properties of three molecular tree construction methods--the unweighted pair-group arithmetic average clustering (UPG), Farris, and modified Farris methods--are examined under the neutral mutation model of evolution. The methods are compared for accuracy in construction of the topology and estimation of the branch lengths, using statistics of these two aspects. The distribution of the statistic concerning topological construction is shown to be as important as its mean and variance for the comparison.

Rapid change in mutation rate in a local population of Drosophila melanogaster.

The lethal and detrimental loads per second chromosome rapidly increased from 1968 to 1970 in a local population of Drosophila melanogaster in Japan (lethal load, from about 0.16 to 0.38; detrimental load, from 0.

Evolutionary change of restriction cleavage sites and phylogenetic inference for man and apes.

A mathematical theory for the evolutionary change of restriction endonuclease cleavage sites is developed, and the probabilities of various types of restriction-site changes are evaluated. A computer simulation is also conducted to study properties of the evolutionary change of restriction sites. These studies indicate that parsimony methods of constructing phylogenetic trees often make erroneous inferences about evolutionary changes of restriction sites unless the number of nucleotide substitutions per site is less than 0.

Estimation of evolutionary distance between nucleotide sequences.

A mathematical formula for estimating the average number of nucleotide substitutions per site (delta) between two homologous DNA sequences is developed by taking into account unequal rates of substitution among different nucleotide pairs. Although this formula is obtained for the equal-input model of nucleotide substitution, computer simulations have shown that it gives a reasonably good estimate for a wide range of nucleotide substitution patterns as long as delta is equal to or smaller than 1. Furthermore, the frequency of cases to which the formula is inapplicable is much lower than that for other similar methods recently proposed.

Evolutionary relationship of DNA sequences in finite populations.

With the aim of analyzing and interpreting data on DNA polymorphism obtained by DNA sequencing or restriction enzyme technique, a mathematical theory on the expected evolutionary relationship among DNA sequences (nucleons) sampled is developed under the assumption that the evolutionary change of nucleons is determined solely by mutation and random genetic drift. The statistical property of the number of nucleotide differences between randomly chosen nucleons and that of heterozygosity or nucleon diversity is investigated using this theory. These studies indicate that the estimates of the average number of nucleotide differences and nucleon diversity have a large variance, and a large part of this variance is due to stochastic factors.

Maximum likelihood estimation of the number of nucleotide substitutions from restriction sites data.

A simple method of the maximum likelihood estimation of the number of nucleotide substitutions is presented for the case where restriction sites data from many different restriction enzymes are available. An iteration method, based on nucleotide counting, is also developed. This method is simpler than the maximum likelihood method but gives the same estimate.

Accuracy of estimated phylogenetic trees from molecular data. II. Gene frequency data.

The accuracies and efficiencies of three different methods of making phylogenetic trees from gene frequency data were examined by using computer simulation. The methods examined are UPGMA, Farris' (1972) method, and Tateno et al.'s (1982) modified Farris method.

Accuracy of estimated phylogenetic trees from molecular data. I. Distantly related species.

The accuracies and efficiencies of four different methods for constructing phylogenetic trees from molecular data were examined by using computer simulation. The methods examined are UPGMA, Fitch and Margoliash's (1967) (F/M) method, Farris' (1972) method, and the modified Farris method (Tateno, Nei, and Tajima, this paper). In the computer simulation, eight OTUs (32 OTUs in one case) were assumed to evolve according to a given model tree, and the evolutionary change of a sequence of 300 nucleotides was followed.

Biases of the estimates of DNA divergence obtained by the restriction enzyme technique.

A mathematical formula for the relationship between the average number of nucleotide substitutions per site and the proportion of shared restriction sites between two homologous nucleons is developed by taking into account the unequal rates of substitution among different pairs of nucleotides. Using this formula, the possible amount of bias of the estimate of the number of nucleotide substitutions obtained by the Upholt-Nei-Li formula for restriction site data is investigated. The results obtained indicate that the bias depends upon the nucleotides in the recognition sequence of the restriction enzyme used, the unequal rates of substitution among different nucleotides, and the unequal nucleotide frequencies, but the primary factor is the unequal rates of nucleotide substitution.

Genetic drift and estimation of effective population size.

The statistical properties of the standardized variance of gene frequency changes (a quantity equivalent to Wright's inbreeding coefficient) in a random mating population are studied, and new formulae for estimating the effective population size are developed. The accuracy of the formulae depends on the ratio of sample size to effective size, the number of generations involved (t), and the number of loci or alleles used. It is shown that the standardized variance approximately follows the chi(2) distribution unless t is very large, and the confidence interval of the estimate of effective size can be obtained by using this property.

DNA polymorphism detectable by restriction endonucleases.

Data on DNA polymorphisms detected by restriction endonucleases are rapidly accumulating. With the aim of analyzing these data, several different measures of nucleon (DNA segment) diversity within and between populations are proposed, and statistical methods for estimating these quantities are developed. These statistical methods are applicable to both nuclear and nonnuclear DNAs.