A two-sample test sensitive to crossing hazards in uncensored and singly censored data

Savage score statistics are employed to develop a test for comparing survival distributions with right-hand singly censored data. The procedure is motivated by the interest in developing a powerful method for determining differences when true survival distributions cross. Examination of small-sample characteristics under the null hypothesis indicate that asymptotic critical values yield a slightly conservative test. Power of the test compares favorably with other criteria, including the modified Smirnov procedure, particularly if there is a single crossing of the survival curves.     

Theoretical analysis of the relation between the cell state and pathways of carbon isotope fractionation in metabolic processes

On a dynamic model of fractionation of carbon isotopes in the living cell there are considered relationships between the distribution of carbon isotopes in the structures approximating basic biochemical fractions, their isotopic composition and parameters characterizing the dynamics of carbon metabolism, i.e. efficient carbon isotope separation factor in pyruvate enzymic decarboxylation, degree of its transformation at primary and secondary decarboxylation and ratios between the currents of carbon substrates. A wide range of variations of cell isotope parameters resulting from the change of its functional states was revealed. Possible applications of the relationships observed for studying biological systems are shown.     

Seed survival and seasonal pattern of seedling emergence in some Leguminosae

Seeds of 11 species of Leguminosae were collected, usually in each of 3 years, and mixed with the top 7·5 cm of sterilised soil confined in cylinders sunk in the ground outdoors and cultivated three times yearly. Emergence was recorded for at least 3 yr. Some seedlings of all species emerged soon after sowing but their numbers varied both within and between species, a probable reflection of the percentage of ‘hard’ seeds in the samples. Appreciable numbers of seedlings appeared in the following 3 yr but few seeds remained viable and dormant after 5 yr. The annual weed Vicia hirsuta was an exception, with an average of 11% of the seeds sown still viable at this time. Most seedlings of Lotus corniculatus, Medicago lupulina, Melilotus altissima, Trifolium repens and Vicia cracca emerged in spring, V. cracca rather later than the others. In contrast, maximum emergence of Trifolium arvense, T. campestre and T. dubium took place from June to September. Limited data indicated a similar pattern for T. striatum and Lathyrus pratensis. Seedlings of Vicia hirsuta emerged from October to May but scarcely at all in summer. Although variation in the percentage of hard seeds influenced the extent of immediate germination and seed persistence, the seasonal patterns in seedling emergence of most species were found to be very consistent.     

Morphological characteristics of testicular tissue in animals subjected to unilateral laser castration

In this paper, results of the morphological studies of mammalian testicular tissue after exposure of one of the testes to powerful laser radiation are reported. The results obtained are compared with those reported in the literature on the biological effect of penetrating radiation. No negative influence of powerful laser radiation is registered at the organism level. The criteria for estimation are the tissue response, morphological picture of spermatogenesis, and reproductive functions of exposed animals and of their progeny.     

A new species of the lichen genusDiploschistes from Australia

Diploschistes hensseniae Lumbsch & Elix is described as new to science. It is characterized by its terricolous habitat, perithecioid closed ascomata, relatively small spores, cylindrical asci, and the presence of diploschistesic and orsellinic acids in addition to lecanoric acid. It occurs on soil in arid regions of Australia.     

Distinctions betweenHordeum bulbosum andH. murinum s.l. in seed and herbarium collections

It is sometimes necessary to identify eitherH. bulbosum orH. murinum on the basis of the inflorescence or seeds alone. The majority of taxonomic keys use the presence of swollen basal culms for the former against the annual habit for the latter. Confusion is due to similarities in inflorescences and spikelet morphology. Lodicules which always persist and are present beside the fruit in a mature caryopsis, and other characters such as the awns of the lemmas of the lateral spikelets enable conclusive distinction.     

Bacterially induced stolon settlement in the scyphopolyp ofAurelia aurita (Cnidaria,Scyphozoa)

Unsettled stoloniferous scyphopolyps ofAurelia aurita Lamarck were offered different substrates for settlement under defined conditions. On addition of different biogenic and abiotic substrates, a pure strain of bacteria, a species of Micrococcaceae, was observed to trigger the settlement of the stolon. The settlement reaction only takes place following direct contact with the bacteria; sterile filtrated culture medium of the same bacterial strain was not able to induce settlement. The bacteria were found to be effective on stolon settlement during the logarithmic growth phase, but not during the stationary phase.