Validation for decision support systems: Recent developments and findings

This paper reviews earlier work on the validation of mathematical models and modeling within Decision Support Systems (DSS), in particular where the DSS were developed to support operations management. The authors found that little validation was carried out in practice. With this work as a base, reasons for the paucity of validation are advanced and comparisons with DSS developed to support marketing management are made. The case for a more appropriate methodology of validation is advanced.     

A lytic factor associated with brucellaphage causing ‘lysis-from-without’

Résumé Des bactériophages de Brucella se sont montrés capables de provoquer une lyse extra-cellulaire, en cultures liquides deB. abortus, en présence de glycine et d'acide éthylène-diamine-tétraacétique. Des traitements au sérum anti-bactériophage, aux enzymes protéolytiques, ou la centrifugation différentielle dans le chlorure de césium n'ont pu séparer l'activité lytique de la particule infectieuse elle-même.

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This study was supported by Public Health Service research grant No. AI 06161 from the National Institute of Allergy and Infectious Diseases and by a World Health Organization research grant. The authors are grateful to Dr.D. Pratt for helpful suggestions and assistance with the density gradient centrifugation.     

利用基因工程菌去除电解废水中的汞离子

利用构建的基因工程菌生物富集真实电解废水中的汞离子。电解废水中除含有2.58mg/L的汞离子外，还含有十种以上的其它成分，且pH值为9．6。实验表明，与重组菌对只含汞离子的实验室模拟废水的处理结果比较，电解废水中其它组份的存在意外地增大了重组菌富集汞离子的作用速率，但同时却使细菌的最大汞富集是降低了30％。废水pH的变化对重组菌的汞富集行为影响很小，说明该基因工程菌能在很宽的pH范围内有效地富集汞。实验还考察了EDTA及离子强度对富集行为的影响。     

Point mutation of an FGF receptor abolishes phosphatidylinositol turnover and Ca2+ flux but not mitogenesis.

Stimulation of certain receptor tyrosine kinases results in the tyrosine phosphorylation and activation of phospholipase C gamma (PLC gamma), an enzyme that catalyses the hydrolysis of phosphatidylinositol (PtdIns). This hydrolysis generates diacylglycerol and free inositol phosphate, which in turn activate protein kinase C and increase intracellular Ca2+, respectively. PLC gamma physically associates with activated receptor tyrosine kinases, suggesting that it is a substrate for direct phosphorylation by these kinases. Here we report that a fibroblast growth factor (FGF) receptor with a single point mutation at residue 766 replacing tyrosine with phenylalanine fails to associate with PLC gamma in response to FGF. This mutant receptor also failed to mediate PtdIns hydrolysis and Ca2+ mobilization after FGF stimulation. However, the mutant receptor phosphorylated itself and several other cellular proteins, and it mediated mitogenesis in response to FGF. These findings show that a point mutation in the FGF receptor selectively eliminates activation of PLC gamma and that neither Ca2+ mobilization nor PtdIns hydrolysis are required for FGF-induced mitogenesis.     

Melanin-concentrating hormone is the cognate ligand for the orphan G-protein-coupled receptor SLC-1.

The underlying causes of obesity are poorly understood but probably involve complex interactions between many neurotransmitter and neuropeptide systems involved in the regulation of food intake and energy balance. Three pieces of evidence indicate that the neuropeptide melanin-concentrating hormone (MCH) is an important component of this system. First, MCH stimulates feeding when injected directly into rat brains; second, the messenger RNA for the MCH precursor is upregulated in the hypothalamus of genetically obese mice and in fasted animals; and third, mice lacking MCH eat less and are lean. MCH antagonists might, therefore, provide a treatment for obesity. However, the development of such molecules has been hampered because the identity of the MCH receptor has been unknown until now. Here we show that the 353-amino-acid human orphan G-protein-coupled receptor SLC-1 expressed in HEK293 cells binds MCH with sub-nanomolar affinity, and is stimulated by MCH to mobilize intracellular Ca2+ and reduce forskolin-elevated cyclic AMP levels. We also show that SLC-1 messenger RNA and protein is expressed in the ventromedial and dorsomedial nuclei of the hypothalamus, consistent with a role for SLC-1 in mediating the effects of MCH on feeding.     

龙门山造山带-川西前陆盆地系统构造事件研究

通过对构造事件形成的产物 (岩浆岩、各种矿物等 )进行氩 -氩年龄测定、裂变径迹年龄测定、ESR年龄测定和计算机模拟 ,得出龙门山造山带 -川西前陆盆地系统自印支期以来 ,共发生了 7次构造事件 :(1)卡尼期末的构造事件 (D1 ) ,形成 S1 和 F1 ,并有区域低温动热变质作用 ;(2 )诺利期末的构造事件 (安县运动 ,D2 ) ,产生川西前陆盆地上三叠统须四段与下伏地层不整合接触和须四段砾岩的分布 ,并有较强的岩浆作用 ;(3)燕山期 (12 0～ 130 Ma,D3) ,有较强的岩浆作用和变质作用 ;(4 )喜马拉雅期 6 0 Ma左右的构造事件 (D4) ;(5 )喜马拉雅期 30～ 40Ma的构造事件 (D5 ) ;(6 )喜马拉雅期 2 0～ 2 5 Ma的构造事件 (D6 ) ;(7)喜马拉雅期 10 Ma的构造事件 (D7)。后 4次构造事件使龙门山造山带 -川西前陆盆地系统发生强烈的冲断作用和隆升作用     

鱼类营养学研究的普遍问题及建议

在确定鱼类对潜在营养源的利用或营养物需求的研究中,常存在一些问题.本文将讨论这些问题,并提出这类实验的一般步骤. 1、饲料 商用饲料需注明饲料及厂家的全称.实验饲料需列出所有原料的标准名称及国际饲料号.精饲料及添加剂需列出原料供应商及地址.基础饲料应能提供实验鱼所需的全部营养.除了所测成分外,饲料的组成应是恒定的.最好能根据消化率数据确定饲料配方.饲料制作的步骤应描述清楚.饲料使用前应冷冻保存.饲料应采用国际上接受的方法进行化学分析. 2、实验条件 应描述饲养单元的大小、位置、水源及水处理方法、水温、流速、溶氧、水质参数、光照条件、实验鱼的详细情况及其他实验条件.养鱼系统包括流水、循环过滤水及静水系统.静水系统不能用于营养需求实验,循环水系统亦不宜用于维生素及无机盐需求量实验. 3、实验设计 每一饲养单元是一个重复,单元内的个体不能看作重复样.每一处理至少需要3个重复.实验鱼需经过一段时间暂养才能用于实验.实验周期至少8周,微营养物需求实验需要12-20周.实验期增重率应在200%-500%以上.饲养单元应随机分配于各个处理.投喂方式可以是饱食或限食.若采用限食投喂,投喂水平应接近饱食. 4、数据评价 如果对照鱼生长率较预期的低,或死亡率较高,或实验结果与预期的不同,则有必要重复实验.需求量实验应得到剂量反应曲线,否则须重新设计实验.建议采用拐点法或回归法确定最低需求量.     

1980—2015年内蒙古森林火灾的时空动态

【目的】林火是森林生态系统中重要的干扰因子,严重影响着森林的结构与功能。内蒙古大兴安岭是我国重要的森林生态系统之一,从内蒙古地区地域、海拔、火灾原因分布等可能导致火灾的时空因素分析林火灾害,为森林防火和管理提供有力的科学依据。【方法】基于遥感影像,借助ArcGIS 10.2和Origin等软件,分析了1980—2015年内蒙古地区森林火灾特点,结合时间、空间的因素,探讨林火的时空动态规律。【结果】内蒙古地区森林火灾时空上表现出规律性分布。受害森林面积年变化存在周期性规律,周期间隔16 a,且春季为林火高发季节,在进行森林防火的资源调节过程中,火灾发生次数较多的4、5月正处于春分、清明和谷雨时节,应以控制火源为主要内容。此外,月初林火发生概率相对较高,应在该时段提高警惕; 林火的发生主要集中在9:00—17:00; 多发于呼伦贝尔市、赤峰市、鄂尔多斯市和兴安盟等地区,其中兴安盟过火面积最大,大兴安岭林区火灾也比较频繁。【结论】内蒙古森林火灾频发,过火面积较大,且火灾频发与人类活动及气候特点息息相关。森林火灾主要由人为活动造成,必须严格控制野外火源、生活用火等。建议在掌握内蒙古自治区森林火灾时空动态特征的基础上,加强防火宣传与教育,并运用科学的森林防火措施,制定合理的森林防护政策。     

乙烯信号转导与合成基因在延长花期中的应用

乙烯对花卉衰老具有强烈的促进作用,是造成花卉衰老的根本原因．本文主要综述了近几年来采用基因工程手段将乙烯信号转导途径和生物合成途径的相关基因转化到植物体内,从而延长花期方面的研究．