Host specificity in copepod parasites of deep-sea fishes

Parasitic copepods belonging to two orders, Siphonostomatoida and Poecilostomatoida, are frequently reported from fish hosts in the deep sea. Three families of copepods are most commonly encountered, Sphyriidae, Lernaeopodidae and Chondracanthidae, but members of another four families, Hatschekiidae, Pennellidae, Philichthyidae and Hyponeoidae, are occasionally recorded. These parasites utilise various deep demersal fishes as hosts, especially species of the most abundant families, Macrouridae, Moridae, Synaphobranchidae and Alepocephalidae. Host specificity levels are variable, as for shallow-water fishes. In contrast, few parasites are regularly reported from fishes inhabiting the pelagic water column away from the bottom and away from the near-surface zone. Only the pennellids Sarcotretes scopeli and Cardiodectes medusaeus appear common on pelagic fishes, in the Atlantic and Pacific respectively. Host specificity levels in these two pennellid species are relatively low. It is speculated that the difficulty of encountering a host in the vast pelagic biome has restricted the diversity of parasitic copepods that have successfully colonized pelagic fishes.     

港口供应链物流能力最优关系契约模型

港口供应链需要大量专用性物流能力,但又普遍存在着专用性物流能力投资不足的问题。通过港口供应链模型,分析了非合作与集中决策条件下能力投资,设计了最优关系契约,有效解决了港口供应链中专用性物流能力投资不足的问题。     

两种酶结合物对棘球蚴三种抗原特异性及敏感性的检测比较

对９４例包虫病患者、４４例非包虫病患者及５０例健康人血清,用羊源林球蚴囊液、原头蚴及生发层抗原,分别进行了酶联金葡菌Ａ蛋白点免疫及酶标记单抗人ＩｇＧ点免疫试验,其结果显示：前者对三种抗原的敏感性分别为９４．７％、９５．７％和９６．８％;后者分别为９２．６％、９３．６％和９３．６％。前者的特异性分别为８１．９％、９２．６％和９２．６％;后者分别为８７．２％、９１．５％和９１．５％。酶联金葡菌Ａ蛋白点免疫除了林球蚴囊液抗原的特异性低于酶标羊抗人ＩｇＧ点免疫外,原头蚴抗原、生发展抗原的特异性和三种抗原的敏感性均比后者高。     

供求不对称原理的新释

市场经济中长期普遍存在的供大于求不对称现象,其内因是需求动力弱而供给动力强,这可用两种新论点来解释。一是在货币“价格”不变的条件下,物品专用性边际效用递减较快,同货币通用性边际效用递减较慢之间产生矛盾所致。二是将历来分开研究的供求关系和公私产权性质结合起来研究,发现不同的产权性质由于产生不同的交易价格而同供求动力的强弱存在极密切的相关关系。本还指出只有不断地进行产业创新才能克服上述不断出现的供求不对称矛盾以及专用性物品边际效用递减的趋势。