The effect of different protein diets on longevity and various biochemical parameters of aged rats]

In this work 23 month old rats were fed for 200 days with different protein diets (NT-diet: 19% protein, 72% of animal origin and LP-diet: 8.8% protein exclusively of vegetable origin). Some metabolic parameters and lifespan (on the base of a 50% death-rate) were determined. The relations of the liver free amino acids glycine + alanine and tyrosine + phenylalanine + branched chain amino acids and the ratio of phenylalanine/tyrosine were determined to be higher in the LP-group. Phenylalanine in liver and urea concentrations in liver and serum were lower in the LP-group. Furthermore the dopamine or serotonin levels were significantly lower in lateral and medial or lateral regions of the hypothalamus respectively in LP-diet fed rats. The norepinephrine content was not modified by the diets. The median lifespan of 23 month old rats was higher by 24% following LP-treatment. These results suggest that the protein component (amino acids) of different diets may modify metabolic parameters and lifespan of animals by mechanisms in which the central regulation may be involved.     

NCFW专家系统的汉语接口

NCFW系统是适合于花岗岩与变质岩地区的勘探地下水专家系统，系统的人机交互既可用菜单（亦称项目单）方式，亦可用汉语对话方式。这两种方式既可混合使用亦能灵活切换。本文着重描述了汉语接口的设计思想、实现中采用关键技术以及系统运行实例。     

A computational method for the LU decomposition of rectangularmatrices and its implications to the realization of 2-D digital filters

The realization of 2-D digital filters based on the lower-upper triangular decomposition of the coefficient matrix is investigated. A numerical method based on the QA decomposition, which has some important characteristics, is proposed for reaching the LU structure. The coefficients in the final LU structure have values favorable to fixed-point arithmetic implementation. Furthermore, the QR structure can be used for the realization and possesses good numerical characteristics in terms of the approximate decomposition scheme. The symmetry in the impulse response coefficient matrix of an octagonally symmetric 2-D FIR filter is utilized to reduce the computational effort spent in the decomposition and the total number of multipliers in the final realization structure     

Blind deconvolution for Doppler centroid estimation in highfrequency SAR

For high-quality SAR (synthetic aperture radar) processing, the Doppler centroid frequency is needed. However, SAR data are sampled along the azimuth direction at the pulse repetition frequency (PRF); the estimation of the Doppler centroid frequency by means of spectral analysis techniques may produce ambiguous results due to aliases. The mathematical expression of the residual error that occurs when SAR data are focused with an incorrect alias of the PRF is thus derived. Then, a blind deconvolution technique is used to estimate the actual PRF replica from the focused image. Squinted X-band data, corresponding to those that will be generated by the SIR-C mission, have been generated from the JPL-AirSAR L- and C-band data by means of an inversion of the focusing process. Even if the real data may show differences with respect to the simulated data, the blind deconvolution method appears to be more precise and robust than the other conventional techniques tested     

Alpha-particle-induced charge collection in p-n junction diodes insemi-insulating GaAs substrates

The bias and angle dependences of the alpha-particle-induced charge collected by GaAs p-n junction diodes are investigated. These diodes, in which the n-layer overlays the p-layer, are fabricated in a semi-insulating GaAs substrate by Si and Mg ion implantation. ²⁴¹ Am placed in a vacuum is used as an alpha-particle source with an initial energy of 4.03 MeV and a fluence of 5.4×10^-5/s/μm². The results show that the collected charge is nearly independent of the applied bias. This bias independence may be further evidence that the charge funneling process is not important in semi-insulating GaAs. A model not incorporating funneling can explain the measured angular dependence. Based on this model, the design principle for the buried p-layer structure is discussed     

Use of nitrogen-15 determinations of purine nitrogen fraction of digesta to define nitrogen metabolism traits in the rumen

A method for direct purine N isolation and determination was modified from the method of Zinn and Owens for rapid determination of purines. By this method, N derived from purines in digesta was measured and collected for 15N determinations. Measurements of purine N in 33 samples of ruminal contents and duodenal digesta of sheep and goats were compared with purine determinations in the same samples. The results showed that essentially all the N in the purines that could be isolated by the Zinn and Owens procedure also could be detected by N isolation and determination. Determinations of 15N in the NH3 N, NAN, and purine N fractions in a continuous culture in vitro showed significant differences in the 15N enrichment curves between diets based on either roasted or raw soybean meal.