新型工业化进程中的消费与高新技术污染

随着新型工业化的发展,污染治理已实现了从单纯的末端治理向在生产过程中治理转变的跨越式发展。但新的环境问题如消费废弃物污染的面更广,内容更多和高新技术污染等相继出现。这些污染应引起人们的广泛关注。     

Unemployment effects of climate policy

This paper models the unemployment effects of restrictions on greenhouse gas emissions, embodying two of the most significant types of short-term economic imperfections that generate unemployment: sectoral rigidities in labor mobility and sectoral rigidities in wage adjustments. A labor policy is also analyzed that would reduce the direct negative economic effects of the emissions restrictions.The politics of limiting greenhouse gas emissions are often dominated by relatively short-term considerations. Yet the current economic modeling of emissions limitations does not embody economic features that are likely to be particularly important in the short term, in particular, the politically sensitive unemployment rate. Moreover, only a few of these studies also consider policies that would offset the negative direct economic effects of emissions restrictions. For plausible estimates of the parameters, the model shows that, with the labor market imperfections, if there were no offsetting policies, the reductions in GNP in the U.S. in the first 10 years after emissions restrictions were imposed would be as much as 4%. However, if there were two policies, instead of just one: a counteracting labor market policy, as well as the emissions restrictions, the negative direct economic effects could be completely eliminated.     

Age-related decline in metabolic competence of small and medium-sized synaptic mitochondria

A computer-assisted morphometric investigation of cytochrome oxidase (COX) activity, selectively evidenced by preferential diaminobenzidine cytochemistry, has been carried out on synaptic mitochondria in the cerebellar cortex of adult and old rats. The ratio (R) of the area of the cytochemical precipitate (CPA) to the overall area of each mitochondrion (MA) was calculated. R refers to the fraction of the inner mitochondrial membrane actively involved in cellular respiration, thus its quantitative estimation constitutes a reliable index of the mitochondrial metabolic competence (MMC). In adult rats a significant negative correlation between MA and R values was found, while in old animals there was just a positive trend. Paired-quartile comparisons of R values showed a significant age-related decrease in small and medium-sized mitochondria, whereas the lowest and not significant age-related reduction was found in oversized organelles. A paired decrease in number and increase in size is reported to be a general trend for mitochondria during aging, but oversized organelles, according to their low R value, constitute a scanty, though functional, compensating reaction. Thus, the present findings support the argument that the currently reported age-related cellular metabolic decay appears to rely both on the decline in MMC of the small and medium-sized mitochondria, and on their specific reduction in number. This novel result is of biological relevance since it is largely the small and medium-sized mitochondria that are required for the provision of adequate amounts of ATP for actual cellular performance, while the significantly enlarged organelles are thought to represent an intermediate ultrastructural feature in mitochondrial genesis and/or remodelling.     

The hand of birds revealed by early ostrich embryos

The problem of resolving the homology of the digits of the avian hand has been framed as a conflict between paleontological and embryological evidence, the former thought to support a hand composed of digits I, II, III, because of similarity of the phalangeal formulae of the earliest known bird Archaeopteryx to that of Mesozoic pentadactyl archosaurs, while embryological evidence has traditionally favored a II, III, IV avian hand. We have identified the critical developmental period for the major features of the avian skeleton in a primitive bird, the ostrich. Analysis of digit anlagen in the avian hand has revealed those for digits/metacarpals I and V, thus confirming previous embryological studies that indirectly suggested that the avian hand comprises digits II, III, IV, and was primitively pentadactyl.