Bayesian experimental design for nonlinear mixed-effects models with application to HIV dynamics

Bayesian experimental design is investigated for Bayesian analysis of nonlinear mixed-effects models. Existence of the posterior risk for parameter estimation is shown. When the same prior distribution is used for both design and inference, existence of the preposterior risk for design is also proven. If the prior distribution used in design is different from that used for inference, sufficient conditions are established for existence of the preposterior risk for design. A case study of design for an experiment in population HIV dynamics is provided.     

草基-鱼塘生态系统的能量转化与养分循环研究

应用模拟试验的方法,研究了“草基-鱼塘”系统中的能量转化与养分循环.结果表明,该系统中饲草对太阳能的利用率为0.83%,鱼对饲料能的转化率为7.3%.与以粮食作为鱼饲料比较,单位面积草地的产鱼当量是粮食作物的1.6倍.鱼对饲料N、P、K的转化率分别为16.8%、32.3%和2.0%.塘泥沉积的N、P分别占饲料的23.4%和56.1%;猪对饲料N、P、K的转化率分别为20.5%、33.7%和4.6%,猪粪尿回收饲料N为36.4%、P为63.8%、K为39.4%.猪-草-鱼结合的基塘系统其能量和养分转化效率均高于单一的养鱼系统.     

Age Determination of Bovine Foetuses

The need for methods for age determination of foetuses is defined. X-ray examination of the foetal head is recommended as the surest basis for age determination. Calculations are made concerning the correlation between cranial length and foetal age, and the methods used for measurements are described in detail. Measurements of the metacarpus and metatarsus may also be used, but they give a poorer correlation. A formula is worked out for age determination based on cranial measurements. On x-ray photographs, tooth development is seen to occur in an obvious sequence. This is described. However, the interpretation of these observations is subjective and requires control material for comparison. The same is true for the sequence of ossification of the skeleton, which in foetuses < 120 days gives the surest basis for evaluation. Here, too, a wide range of control material for comparison is necessary. The sequence in the appearance of body hair — development and eruption — is noted, as far as the head is concerned. This alone gives an insecure basis for evaluation. By using the 4 systems of parameters mentioned, the age of a foetus can be determined within an error of ± 4—5 days.     

草基—鱼塘生态系统的能量转化与养分循环研究

应用模拟试验的方法,研究了“草基-鱼塘”系统中的能量转化与养分循环．结果 表明,该系统中饲草对太阳能的利用率为 ０． ８３％,鱼对饲料能的转化率为 ７． ３％．与以粮 食作为鱼饲料比较,单位面积草地的产鱼当量是粮食作物的１．６倍．鱼对饲料Ｎ、Ｐ、Ｋ的 转化率分别为１６．８％、３２．３％和２．０％．塘泥沉积的Ｎ、Ｐ分别占饲料的２３．４％和５６．１％; 猪对饲料 Ｎ、 Ｐ、 Ｋ的转化率分别为 ２０． ５％、 ３３． ７％和 ４． ６％,猪粪尿回收饲料 Ｎ为 ３６． ４％、 Ｐ为 ６３． ８％、 Ｋ为 ３９． ４％．猪-草-鱼结合的基塘系统其能量和养分转化效率均高于单一的 养鱼系统．     

湖南土家族的体质特征

以20至69岁的湖南土家族人为观察测量对象,根据1392人(男896,女496)的身高,1038人(男668,女370)的头部测量,364人(男235,女129)的五官测量和观察结果,分析该民族的体质特征,并与国内其他民族相比较。     

A general purpose computerized display and analysis system for image processing in nuclear medicine.

In this work a general purpose image processor is described, which takes into account the special features and the various requirements for analysing images in nuclear medicine. A new approach for system structure involving encoding and representing medical images is given. This encoder, which is part of the image processor, is efficient especially for long-term storage and for certain pattern recognition in medical imaging. In this processor a statistical package is incorporated for collecting medical statistics using the acquired patient data. This information is used together with the encoder for an automated diagnostic system.     

维吾尔族的体质特征研究

１９９１年５月,对新疆伊梨维吾尔族５２９人（男２７１,女２５８）进行了活体观察和测量。观察２９项,测量９２项。维吾尔族的主要特征是：黑直发,黑褐色眼,眉毛较浓密,大都有上眼脸皱褶,鼻根中等偏高,大多为直形鼻,鼻尖向前,鼻基部下垂,大多有达尔文结节,耳垢湿型。头面部指数分型,属于特短头型,阔头型和高头型。身材中等偏高,平均身高男１６８．６毫米,女１５７８．８毫米。     

Application of a miniature biochip using the molecular beacon probe in breast cancer gene BRCA1 detection

We report for the first time the application of a biochip using the molecular beacon (MB) detection scheme. The usability of this biochip novel detection system for the analysis of the breast cancer gene BRCA1 is demonstrated using molecular beacon probes. The MB is designed for the BRCA1 gene and a miniature biochip system is used for detection. The performance of the biochip-MB detection system is evaluated. The optimum conditions for the MB system for highest fluorescence detection sensitivity are investigated for the detection system. The detection of BRCA1 gene is successfully demonstrated in solution and the limit of detection (LOD) is estimated as 70 nM.     

Does bone mineralization reflect economic conditions? An examination using a national US sample

BACKGROUND: Bone density is the most important determinant of osteoporotic fractures, which lead to significant morbidity, disability and mortality for older persons, particularly women. Sensitive periods for bone mineralization in infancy, childhood and adolescence overlap with those for height attainment. After peak density is reached in early adulthood, there is age-related decline. We ask whether bone density, as height, reflects economic conditions. SUBJECTS AND METHODS: Using the third National Health and Nutrition Examination Survey, a probability sample of the US population which over-sampled Blacks and Mexican Americans, we examine the associations between adult bone mineral content (BMC) adjusted for bone and body size and three economic indicators: education, height and the poverty income ratio (PIR). We compare four groups: US-born Whites, Blacks and Mexican Americans and Mexican-born Mexican Americans. RESULTS: Education is positively associated with BMC only for White women, although there are similar, non-significant associations for Black women and White and Black men. For women, BMC is more strongly associated with height for Mexican Americans, especially the Mexican-born, than for Whites. For men, the only significant association is a negative one with education for men born in Mexico. PIR is not significantly associated with BMC, although there is pattern of lower income being associated with lower BMC for Whites and Blacks and higher BMC for Mexican Americans. CONCLUSION: Bone density does not reflect economic conditions as strongly or consistently as does physical stature. However, for women there is evidence that lower economic status in childhood or adolescence is associated with lower bone density.     

Mitochondrial function and toxicity: role of the B vitamin family on mitochondrial energy metabolism

The B vitamins are water-soluble vitamins required as coenzymes for enzymes essential for cell function. This review focuses on their essential role in maintaining mitochondrial function and on how mitochondria are compromised by a deficiency of any B vitamin. Thiamin (B1) is essential for the oxidative decarboxylation of the multienzyme branched-chain ketoacid dehydrogenase complexes of the citric acid cycle. Riboflavin (B2) is required for the flavoenzymes of the respiratory chain, while NADH is synthesized from niacin (B3) and is required to supply protons for oxidative phosphorylation. Pantothenic acid (B5) is required for coenzyme A formation and is also essential for alpha-ketoglutarate and pyruvate dehydrogenase complexes as well as fatty acid oxidation. Biotin (B7) is the coenzyme of decarboxylases required for gluconeogenesis and fatty acid oxidation. Pyridoxal (B6), folate and cobalamin (B12) properties are reviewed elsewhere in this issue. The experimental animal and clinical evidence that vitamin B therapy alleviates B deficiency symptoms and prevents mitochondrial toxicity is also reviewed. The effectiveness of B vitamins as antioxidants preventing oxidative stress toxicity is also reviewed.     

The effect of glutamine concentration on the activity of carbamoyl-phosphate synthase II and on the incorporation of [3H]thymidine into DNA in rat mesenteric lymphocytes stimulated by phytohaemagglutinin.

The maximum catalytic activities of carbamoyl-phosphate synthase II, a limiting enzyme for pyrimidine nucleotide synthesis, are very much less than those of glutaminase, a limiting enzyme for glutamine utilization, in lymphocytes and macrophages; and the flux through the pathway for pyrimidine formation de novo is only about 0.4% of the rate of glutamine utilization by lymphocytes. The Km of synthase II for glutamine is about 16 microM and the concentration of glutamine necessary to stimulate lymphocyte proliferation half-maximally is about 21 microM. This agreement suggests that the importance of glutamine for these cells is provision of nitrogen for biosynthesis of pyrimidine nucleotides (and probably purine nucleotides). However, the glutamine concentration necessary for half-maximal stimulation of glutamine utilization (glutaminolysis) by the lymphocytes is 2.5 mM. The fact that the rate of glutamine utilization by lymphocytes is markedly in excess of the rate of the pathway for pyrimidine nucleotide synthesis de novo and that the Km and 'half-maximal concentration' values are so different, suggests that the glutaminolytic pathway is independent of the use of glutamine nitrogen for pyrimidine synthesis.     

A surgical operating apparatus for fish and its use in the pinealectomy of salmonids

A surgical operating apparatus for fish that is effective for cranial surgery is described. The fishes are secured with clamp-arms which extend against the pectoral and pelvic girdles. The head is held by a plexiglass mouthpiece, designed specifically for the fish species under investigation. The mouthpiece is also responsible for gill irrigation. The use of the apparatus for the surgical pinealectomy of salmonids is described.     

演化极端结合分支分类方法

从生物演化的逆方向考虑,提出一种聚合的分支分类运算方法,称为演化极端结合分支分类法。文章阐明其设计思路、演算步骤,并以实例具体说明其演算过程。最后以演化长度系数、合理解与合理方法等概念,对演化极端结合法进行评价。     

Removal of Histological Sections from Glass for Electron Microscopy: Use of Quetol 651 Resin and Heat

A method is described for using the epoxy resin Quetol 651 and heat for convenient and rapid separation of conventional histological sections from glass slides for subsequent ultrathin sectioning for retrospective electron microscopy. The same method is useful when Epon-Araldite is substituted for the Quetol 651 resin.     

Statistical Testing for Seasonality in Data with Multiple Peaks and Troughs

EDWARDS'S test for seasonality is extended to multiple peaks and troughs. It is shown how the extended statistic may be adjusted for the population at risk and for unequal lengths of time intervals in the cycle of seasons. A simulation study shows that the extended test statistic is, for sample sizes N ≧ 100, very specific in detecting the number of peaks and troughs for which it is intended. The associated method of parameter estimation is also assessed; for N ≦ 100, the amplitude of a possibly adequate simple harmonic model is estimated well, but the initial value of the phase angle is not. Estimated percentage points for the extended test statistic are tabulated, and some recommendations are offered regarding usage of this method.     

Systematics,conservation and sustainable development

The contribution of systematics to conservation and sustainable use of species is discussed. An adequate inventory of species is required for both areas and recent field work shows that the inventory is far from complete. This supports the first mission of Agenda 2000 which is to discover described and inventory global species diversity. The importance of making these data available in data base format is stressed. Sound systematics is a necessity for conservation legislation where control depends on the ability to identify organisms correctly. The establishment of reserves is also dependent upon data from systematics about centres of diversity and endemism and examples of this are given. Molecular systematics has made new tools available to conservation such as genetic fingerprinting which is useful both to breeding programmes of rare species and for identification for legal proceedings.Systematics is also one of the foundations for programmes of sustainable development especially in the search for new crops, non-timber forest plants from extraction forests and the identification of wild relatives of crop species. Examples of the role of systematics in a fuelwood programme in Zimbabwe, a sustainable development programme in northeast Brazil and in the search for a chemical component with medicinal properties for curing AIDS are given. The more predictive a classification we can develop using modern cladistic and molecular techniques the more useful systematics will be for both conservation and sustainable development. The goal of Agenda 2000 to organize the information derived from the programme in an efficiently retrievable form that best meets the needs of science and society is a laudable target that is crucial for conservation and the sustainable use of the plant resources of the world.     

Why does Escherichia coli have two primary pathways for synthesis of glutamate?

Escherichia coli has two primary pathways for glutamate synthetase-glutamate synthase pathway is known to be essential for synthesis at low ammonium concentrations and for regulation of the glutamine pool, but the necessity for glutamate dehydrogenase (GDH) has been uncertain. The results of competition experiments between the wild type and a GDH-deficient mutant during nutrient-limited growth and of direct enzyme measurements suggest that GDH is used in glutamate synthesis when the cell is limited for energy (and carbon) but ammonium and phosphate are present in excess, while the glutamine synthetase-glutamate synthase pathway is used when the cell is not under energy limitation. The use of alternative routes for glutamate synthesis implies that the energy cost of biosynthesis may be less when energy is limited than when energy is unlimited.     

Hill coefficient for estimating the magnitude of cooperativity in gating transitions of voltage-dependent ion channels

A frequently used measure for the extent of cooperativity in ligand binding by an allosteric protein is the Hill coefficient, obtained by fitting data of initial reaction velocity (or fractional binding saturation) as a function of substrate concentration to the Hill equation. Here, it is demonstrated that the simple two-state Boltzmann equation that is widely used to fit voltage-activation data of voltage-dependent ion channels is analogous to the Hill equation. A general empiric definition for a Hill coefficient (n(H)) for channel gating transitions that is analogous to the logarithmic potential sensitivity function of Almers is derived. This definition provides a novel framework for interpreting the meaning of the Hill coefficient. In considering three particular and simple gating schemes for a voltage-activated cation channel, the relation of the Hill coefficient to the magnitude and nature of cooperative interactions along the reaction coordinate of channel gating is demonstrated. A possible functional explanation for the low value of the Hill coefficient for gating transitions of the Shaker voltage-activated K(+) channel is suggested. The analogy between the Hill coefficients for ligand binding and for channel gating transitions further points to a unified conceptual framework in analyzing enzymes and channels behavior.     

Influence of oxygen and substrate concentrations on the ideal film thickness and the maximum overall substrate uptake rate in microbial film fermenters

The criterion for the oxygen limitation of substrate uptake in microbial film fermenters is expressed in terms of diffusion coefficients, utilization coefficients, and the free solution concentrations of substrate and oxygen. It is proposed that the ideal film thickness in such fermenters is equal to the penetration depth of the limiting substrate. The ideal film thickness is calculated, in terms of the parameters contained in the criterion for oxygen limitation, for three separate kinetic rate expressions. It is found that for the air–glucose–microbe system a simplified kinetic rate expression can be used and the region of dependence on two substrates is shown to be very limited. This is not true for other systems. Maximum uptake rates are calculated for a range of concentrations. Finally, it is shown that the procedure used can be generalized to determine the limiting substrate in a multisubstrate system and to calculate ideal film thickness and uptake rates for any pair of substrates where the kinetics of substrate uptake are known for the individual microorganism.     

An ab initio study of valence isomerization in the HOCl-HClO system

Hartree-Fock level and post Hartree-Fock level molecular orbital calculations have been completed for HOCl and its valence isomer, HClO. Ground state geometries have been determined for each molecule. The energy change for the reaction HOCl→HClO is estimated to be 67±5 kcal/mol endothermic and the activation energy for the process is 74±5 kcal/ mol. The transition state for the reaction is identified and discussed. A vibrational analysis has been carried out for both HOCl and HClO. The calculated photoelectron spectrum is discussed for each of the molecules.