Within tree variability of lignin composition in <Emphasis Type="Italic">Populus</Emphasis>

Clonal variability among trees has been studied and found to have profound effects on nearly all measured phenotypes. However, when estimating wood properties it is important to consider variability within the tree. The position in which a tree is sampled could have a large influence on biomass characterization. We looked at variability in lignin content as height increases and as the number of rings from the pith increase in Populus species. Seven trees were destructively sampled; subsamples were obtained along a 2.4 m length of each stem and across increment rings. All samples were analyzed by pyrolysis molecular beam mass spectroscopy to map the variability across sampling heights and/or ring positions in lignin content. The results of this study indicate that when sampling a tree, there is more variability from ring to ring than at different heights going up the stem.     

中文版阔叶材胶合板标准面市

2004年10月25日,美国弗吉尼亚州亚历山大(ALEXANDRIA,Va)消息。国际木制品协会(International Wood Products Association,IWPA)发布公告,其制订的通用工业标准,《IHPA Grade等级进口阔叶材胶合板采购标准》最近翻译出版了中文版(繁体)。     

Economic returns of disease-affected extensive shrimp farming in southwest Bangladesh

One hundred and two brackish water shrimp farms in Shyamnagar Upazila of Satkhira District, Bangladesh, were surveyed to study their costs and returns. Key data were collected, using a questionnaire survey from January to August 2002. Profitability of operations was affected by fluctuating yields and prices due to diseases, and generated economic risk. The average total cost of production per hectare was 63,437.57 Bangladeshi taka (tk) (US$1,084.40/ha). The farmers achieved a variable yield of black tiger shrimp (Penaeus monodon), ranging from 7.48 kg/ha to 455.03 kg/ha, with a mean yield of 146.39 kg/ha, through multi-stock and multi-harvest methods. The gross and net incomes per hectare were tk49,999.87 (US$854.69) and tk40,307.04 (US$689.01), respectively. Of the total biomass, 44% came from P. monodon, while the rest (23% and 33%) came from other shrimp and finfish respectively. The return to total cost of P. monodon was a negative profit (tk0.78).     

联合纵队

怎样的队伍才能称之为梦之队呢?狭义上的梦之队通常是指那支在1992年巴塞罗那夏季奥运会上最终夺得金牌的美国男子篮球队。如今俄罗斯女子网球队已经可以进入梦之队大军了,虽然她们没有网罗女子网坛所有的顶尖选手,但是她们是女子网坛最有深度,最不可战胜的整体。     

Reality vs. rhetoric – a survey and evaluation of tsetse control in East Africa

Odor baited methods of controlling tsetse have received considerable attention as ecologically friendly ways for African farmers to reduce their levels of livestock trypanosomosis. Over the last decade, a number of tsetse control projects have been set up in East Africa using these methods. Although much has been written, few hard data are available regarding their ongoing success, problems, and sustainability. To evaluate the situation on the ground, the authors conducted a series of site visits to a number of such tsetse control projects in Kenya. A comparison of these projects with others across the region identified the possible constraints to a wider uptake of these methods. Poor information, coupled with inappropriate research and development policies, were found to be the key constraints. These could be overcome with a farmer-based approach to control, with a better application of existing techniques, and with a greater role for veterinarians. Tsetse control needs to become demand rather than supply driven, if it is to bean important component of livestock disease control in Africa. This revised version was published online in June 2006 with corrections to the Cover Date.     

Induction of hepatic microsomal enzymes in chickens effected by various persistent foreign materials]

Changes in the levels of microsomal proteins, in the activity of microsomal aniline hydroxylase, and in the effectivity of Thiopental were studied in chickens given the Czechoslovak-produced type of polychlorinated biphenyls - Delor 103. The increased activity of aniline hydroxylase and the decrease of Thiopental sleeping time in chickens exposed to the action of Delor 103 indicate that this preparation is able to induce liver microsomal enzymes in doses as low as 5 mg per kg of feed. The induction of liver microsomal enzymes appears to be an important factor, able to exercise a direct influence on the biotransformation of various biologically important substances in the organism of chickens.