Management from the viewpoint of Lake Victoria fisheries

Fisheries science is concerned with ultimate yield prediction and control. The subject deals with the study of natural history of stocks and the dynamics of fish populations. The multiple species fisheries of Lake Victoria are undergoing rapid development. Already, some of the highly valued fish species have been reduced to very low population levels. The most abundant but less relished Haplochromis spp. remain underutilized. The real problem in management is to win acceptance for regulations that foster increasing productivity in the industry, without slavish adherence to status quo.

Performance of thin film carbon materials and carbon nanotubes as cold cathodes

The field emissions from three different types of carbon films are studied using a Kiethly voltage-current source-measure unit under computer control. The three types of carbon films are : 1) a-C:H:N deposited using an inductively coupled rf PECVD process, where the N content in the films can be as high as 30 at %; 2) cathodic arc deposited tetrahedral amorphous carbon with embedded regions of carbon nanotube and anion structures and 3) unoriented carbon nanotube films on a porous substrate. The films are formed by filtering a solution of nanotubes dispersed in alcohol through the pores and drying.

中国八种家鼠C-带核型的比较研究

对我国大陆八种家鼠的C-带核型进行了比较研究, 并将C-带差异数量化 进 行模糊聚类分析 结果表明: 八种家鼠的C-带核型相互间存在一定的差异, 通过 分析, 得到了八种家鼠的聚 类分析分支图, 分为二大组: 斯氏家鼠和环齿鼠为 一组 其余种类为另一组。图版1图1表4参23

蝠蛾属二新种记述 (鳞翅目: 蝙蝠蛾科)

该文报道了云南西北部分布的蝠蛾属二新种: 白纹蝠蛾 Hepialus albipictus sp. nov., 金沙蝠蛾 Hepialus jinshaensis sp. nov., 两新种采自雪山高寒草甸之中, 是冬虫夏草真菌的寄主昆虫。

Comparative studies on parallel and antiparallel duplex and triplex DNA

Parallel strand models for base sequences d(A)(10). d(T)(10), d(AT)(5) . d(TA)(5), d(G(5)C(5)). d(C(5)G(5)), d(GC)(5) . d(CG)(5) and d(CTATAGGGAT). d(GATATCCCTA), where reverse Watson-Crick A-T pairing with two H-bonds and reverse Watson-Crick G-C pairing with one H-bond or with two H-bonds were adopted, and three models of d(T)(14). d(A)(14). d(T)(14) triple helix with different strand orientations were built up by molecular architecture and energy minimization. Comparisons of parallel duplex models with their corresponding B-DNA models and comparisons among the three triple helices showed: (i) conformational energies of parallel AT duplex models were a little lower, while for GC duplex models they were about 8% higher than that of their corresponding B-DNA models; (ii) the energy differences between parallel and B-type duplex models and among the three triple helices arose mainly from base stacking energies, especially for GC base pairing; (iii) the parallel duplexes with one H-bond G-C pairs were less stable than those with two H-bonds G-C pairs. The present paper includes a brief discussion about the effect of base stacking and base sequences on DNA conformations. (C) 1997 Academic Press Limited.