Evolutionary significance of morphospecies: a test with cheilostome bryozoa

Much of the controversy concerning the theory of punctuated equilibrium stems from skepticism about the biologic validity of fossil morphospecies, particularly for supposedly simple invertebrate taxa like cheilostome Bryozoa that form the bulk of the fossil record. However, evidence from breeding experiments and protein electrophoresis shows that morphospecific identity of cheilostomes is heritable and that morphospecies are genetically distinct with no indication of morphologically cryptic species. Thus paleontologists can study cheilostome evolution at the species level, and previously demonstrated pattems suggesting punctuated speciation in cheilostomes should be taken at face value.     

Hydrogen-Aluminum Clays: A Third Buffer Range Appearing in Potentiometric Titration

Wyoming montmorillonite (bentonite, particles 2 to 0.2 micro in diameter) treated with hydrogen-ionsaturated resin shows, on titration in 1N KNO(3) with NaOH by a continuously recording instrument, a third buffer range between pH 5.5 and 7.6 in addition to the first range where exchangeable hydronium is neutralized and the second range where a reaction with exchangeable aluminohexahydronium, Al(OH(2))(6)(3+), occurs. The third range increases considerably when the hydrogen-ion-saturated clay is aged, and is attributed to basic aluminum compounds formed in the presence of negative charges of montmorillonite, comparable to "third range" buffering noted in aged, partially neutralized aluminum chloride solutions.     

先进的陆地和海底管道涂覆技术

油气工业的快速发展给诸如在寒冷的气候和深水环境中、具有独特应用地位的管道涂覆技术的革新带来了巨大的挑战和机遇.突出强调了几种独特的、先进的并已经过证实的管道涂覆技术,这些技术适用于陆地和海底管道的保护,包括高效复合涂层系统(HPCC)、高强度钢粉末涂层低温涂覆技术和Thermotite稳流保证技术.给出了一些案例和收集的技术数据.     

Cigarette craving, smoking withdrawal, and clonidine

Clonidine, an alpha-2-adrenergic agonist, significantly reduces opiate withdrawal. Fifteen heavy smokers abstained from cigarettes on three separate occasions and received instead clonidine, placebo, or the benzodiazepine alprazolam. Clonidine and alprazolam diminished withdrawal symptoms. The two drugs suppressed anxiety, tension, irritability, and restlessness equally but clonidine had a greater effect than alprazolam on cigarette craving. These observations suggest that noradrenergic activity is a common feature in the pathophysiology of withdrawal and that a special relationship exists between central noradrenergic activity and craving.     

Phosphonomycin, a new antibiotic produced by strains of streptomyces

Phosphonomycin is a newly discovered antibiotic produced by streptomycetes. It is effective, when administered by the oral route, to mice infected with Gram-positive or Gram-negative microorganisms. The antibiotic is bactericidal and inhibits cell-wall synthesis.     

A reexamination of the crop water stress index

Summary Hand-held infrared radiometers, developed during the past decade, have extended the measurement of plant canopy temperatures from individual leaves to entire plant canopies. Canopy temperatures are determined by the water status of the plants and by ambient meteorological conditions. The crop water stress index (CWSI) combines these factors and yields a measure of plant water stress. Two forms of the index have been proposed, an empirical approach as reported by Idso et al. (1981), and a theoretical approach reported by Jackson et al. (1981). Because it is simple and requires only three variables to be measured, the empirical approach has received much attention in the literature. It has, however received some criticism concerning its inability to account for temperature changes due to radiation and windspeed. The theoretical method is more complicated in that it requires these two additional variables to be measured, and the evaluation of an aerodynamic resistance, but it will account for differences in radiation and windspeed. This report reexamines the theoretical approach and proposes a method for estimating an aerodynamic resistance applicable to a plant canopy. A brief history of plant temperature measurements is given and the theoretical basis for the CWSI reviewed.     

Potassium release on drying of soil samples from a variety of weathering regimes and c clay mineralogy in China

Thirty two soil samples from China were analyzed for exchangeable K before and after drying. Most soil samples were higher in exchangeable K after air-drying and ovendrying (60°C) than when wet. Soil clay minerals, especially clay-size mica, affected K released in air-dry and oven-dry samples. According to composition of clay minerals of air-dried samples, five classes were recognized. Soil samples with high mica and montmorillonite have the highest exchangeable K. Samples that contained higher kaolinite than mica had lower exchangeable K. Samples with higher kaolinite than quartz and mica had still lower exchangeable K. Samples of sandy soils contained very low exchangeable K. When quartz was the main mineral, the samples that had kaolinite and gibbsite as the main clay minerals had very low exchangeable K. The degree of weathering (weathering mean) bore an inverse relationship to the amount of K released on drying in air or at 60°C. Udults and Udalfs (Red Earths) of southeastern China, because of their high K release on being dried, are inferred to have received fine mica from the Western Desert dust rainout, reported to Liu et al. (1981).     

Genetic diversity in the Chamaecytisus proliferus complex (Fabaceae: Genisteae) in the Canary Islands in relation to in situ conservation

Summary Electrophoresis was carried out for six isozyme systems on 175 accessions of the seven morphological forms of Chamaecytisus proliferus (L. fil.) Link (Fabaceae: Genisteae) from the Canary Islands. Previous studies have shown that there is clear differentiation into morphological and ecological forms. The underlying genetic variation as visualised by studying isozymes does not reflect this. While substantial genetic diversity can be identified, this was found to be as much within as between morphological forms. This genetic diversity was found to decrease from east to west, and reflects the pattern of variation remaining after colonisation of the individual islands, which is assumed to have progressed in the same direction. Subsequently, adaptive radiation has given rise to the overlying morphological variation as exhibited in the seven morphological forms.In terms of in situ conservation, overall genetic diversity can be easily conserved in the abundant populations occurring in the east of the archipelago, while more attention is required for conservation of the much rarer morphological forms found in the west, despite their relative lack of isozyme diversity.Abbreviations ACO aconitase - ADH alcohol dehydrogenase - IDH Asocitrate dehydrogenase - MDH malate dehydrogenase - PGD 6-phosphogluconate dehydrogenase - PGM phosphoglucomutase - CA cluster analysis - PCA principal component analysis