大动态范围的环境噪声自动测量仪的研制

研制了一台动态范围为90dB以上的环境噪声自动监测及统计分析仪器。可以适用于声级起伏变化很大的环境噪声和交通噪声的全量程监测,并可以把测量结果和统计分析结果自动显示和打印出来,解决了随机性较强的环境噪声的自动监测问题。仪器內部有两只对数放大器,由于器件特性的限制,每只对数放大器的动态范围约60dB左右,但通过微处理器对双通道对数放大器的交替采样,并经过数据处理,实现了二对数放大器的测量动态范围的自动连接,这样扩大了量程(大于90dB)实现了仪器的全量程测试。     

Plasma catecholamines in children

Summary Plasma catecholamine concentrations in 46 children of various ages were determined by a sensitive radioenzymatic assay. Noradrenaline levels were found to be in the same range as in adults, whereas adrenaline levels in a few of the children were abnormally high.     

Tests of the helix dipole model for stabilization of alpha-helices

Charged groups play a critical role in the stability of the helix formed by the isolated C-peptide (residues 1-13 of ribonuclease A) in aqueous solution. One charged-group effect may arise from interactions between charged residues at either end of the helix and the helix dipole. We report here that studies of C-peptide analogues support the helix dipole model, and provide further evidence for the importance of electrostatic interactions not included in the Zimm-Bragg model for alpha-helix formation.     

Molecular structure of r(GCG)d(TATACGC): a DNA--RNA hybrid helix joined to double helical DNA

The molecule r(GCG)d(TATACGC) is self-complementary and forms two DNA--RNA hybrid segments surrounding a central region of double helical DNA; its molecular structure has been solved by X-ray analysis. All three parts of the molecule adopt a conformation which is close to that seen in the 11-fold RNA double helix. The conformation of the ribonucleotides is partly determined by water molecules bridging between the ribose O2' hydroxyl group and cytosine O2. The hybrid-DNA duplex junction contains no structural discontinuities. However, the central DNA TATA sequence has some structural irregularities.     

Genetic variation at the alcohol dehydrogenase locus inDrosophila melanogaster: A third ubiquitous allele

Summary A 3rd allele at theAdh locus,Adh ^FCh.D., has been found at polymorphic frequencies in natural populations ofD. melanogaster. The ADH-FChD enzyme has properties distinct from those of the 2 more common forms of ADH. TheAdh polymorphism should now be analyzed as a triallelic system.     

The role of macroeconometric models in forecasting and policy analysis in the united states

This article stresses how little is known about the quality, particularly the relative quality, of macroeconometric models. Most economists make a strict distinction between the quality of a model per se and the accuracy of solutions based on that model. While this distinction is valid, it leaves unanswered how to compare the‘validity’of conditional models. The standard test, the accuracy of ex post simulations, is not definitive when models with differing degrees of exogeneity are compared. In addition, it is extremely difficult to estimate the relative quantitative importance of conceptual problems of models, such as parameter instability across‘policy regimes’ In light of the difficulty in comparisons of conditional macroeconometric models, many model-builders and users assume that the best models are those that have been used to make the most accurate forecasts are those made with the best models. Forecasting experience indicates that forecasters using macroeconometric models have produced more accurate macroeconomic forecasts than either naive or sophisticated unconditional statistical models. It also suggests that judgementally adjusted forecasts have been more accurate than model-based forecasts generated mechanically. The influence of econometrically-based forecasts is now so pervasive that it is difficult to find examples of‘purely judgemental’forecasts.     

Effect of gum Arabic on aminopyrine demethylation in rats

Summary Stimulation of aminopyrine demethylation induced in rats by oral or i.p. administration of phenobarbital was partially inhibited in animals receiving daily treatments of 2×200 mg/kg gum Arabic p.o.     

Effect of cholinesterase inhibitors on differentiation of cultured sympathicoblasts

Summary The 2 cholinesterase inhibitors, eserine and BW 284 C 51, inhibited the nerve fibre growth and differentiation of immature sympathicoblasts at low concentrations. The effect was nerve cell-specific and appeared in the course of the in vitro development, indicating that cholinesterases might play an important role in the early differentiation of sympathicoblasts.