大学课程论文教学中存在问题研究

在分析当前高校课程论文教学现状的基础上,指出其中普遍存在的问题及原因。近年来的教学改革实践表明:采取学生分组、分类指导、学生自评和教师评价相结合的方法可以有效地提高课程论文的教学效果。此外,还提出一些改进课程论文教学的合理化建议。     

Review: Hyperthermia and fever during pregnancy

An episode of hyperthermia is not uncommon during pregnancy. The consequences depend on the extent of temperature elevation, its duration, and the stage of development when it occurs. Mild exposures during the preimplantation period and more severe exposures during embryonic and fetal development often result in prenatal death and abortion. Hyperthermia also causes a wide range of structural and functional defects. The central nervous system (CNS) is most at risk probably because it cannot compensate for the loss of prospective neurons by additional divisions by the surviving neuroblasts and it remains at risk at stages throughout pre- and postnatal life. In experimental animals the most common defects are of the neural tube, microphthalmia, cataract, and micrencephaly, with associated functional and behavioral problems. Defects of craniofacial development including clefts, the axial and appendicular skeleton, the body wall, teeth, and heart are also commonly found. Nearly all these defects have been found in human epidemiological studies following maternal fever or hyperthermia during pregnancy. Suggested future human studies include problems of CNS function after exposure to influenza and fever, including mental retardation, schizophrenia, autism, and cerebral palsy.     

Solving dynamical inverse problems by means of Metabolic P systems

MP (Metabolic P) systems are a class of P systems introduced for modelling metabolic processes. We refer to the dynamical inverse problem as the problem of identifying (discrete) mathematical models exhibiting an observed dynamics. In this paper, we complete the definition of the algorithm LGSS (Log-gain Stoichiometric Stepwise regression) introduced in Manca and Marchetti (2011) for solving a general class of dynamical inverse problems. To this aim, we develop a reformulation of the classical stepwise regression in the context of MP systems. We conclude with a short review of two applications of LGSS for discovering the internal regulation logic of two phenomena relevant in systems biology.     

Sequential feeding with variations in energy and protein levels improves gait score in meat-type chickens

Feeding broilers by alternating different diets for 1 or 2 days is known as sequential feeding, and it possibly reduces leg problems since it slows down early growth and may enhance general activity. The present study compared continuous feeding with a standard diet (C: metabolisable energy = 12.55 MJ/kg, crude protein = 190 g/kg) with alternations of a high-energy/low-protein diet (E+P-:+7% ME; -20% CP) and a low-energy/high-protein diet (E-P+: -7% ME,+20% CP) and investigated its effects on growth, behaviour and gait score in 352 male Ross broiler chickens. Sequential feeding was carried out during ten 48-h sequential-feeding cycles from 8 to 28 days of age. Three treatments were compared: complete diet (C) and two alternations of diets varying in protein and energy contents (S1: E+P- followed by E-P+; and S2: E-P+ followed by E+P-). Chickens received the same feed during the starter and finisher periods (0 to 7 and 29 to 38 days of age). Body weight (BW), feed intake, general activity and gait score, bone quality and carcass conformation were measured to evaluate leg condition and general performance. Sequential feeding significantly reduced BW at 28 days of age (S1: -9.1%; S2: -3.7%/C group; P < 0.05) and S1 were lighter than S2. In both sequential groups, time spent standing increased (C: 28%; S1:33%; S2: 35%; P < 0.05) and leg abnormalities decreased (mean gait score: C: 2.61; S1: 2.45; S2: 2.38; P < 0.02). This improvement was not related to changes in bone quality. BW at slaughter was impaired in Group S1 only, and the feed conversion ratio throughout the rearing period was not significantly impaired by sequential feeding. However, abdominal fat was higher in the S2 group. Sequential feeding using diets varying in energy and crude protein can be a useful method of reducing leg problems in broilers since it improves gait score without impairing growth performance when used as early as 8 days of age and up to not less than 8 days before slaughter in order to compensate for reduced growth. This improvement can be explained by reduced early growth and enhanced motor activity. However, it appears that the low-energy diet should be given first in order to avoid a reduction in BW at slaughter.     

A survey of unresolved problems in life cycle assessment

Background, aims, and scope  Life cycle assessment (LCA) stands as the pre-eminent tool for estimating environmental effects caused by products and processes from ‘cradle to grave’ or ‘cradle to cradle.’ It exists in multiple forms, claims a growing list of practitioners, and remains a focus of continuing research. Despite its popularity and codification by organizations such as the International Organization for Standards and the Society of Environmental Toxicology and Chemistry, life cycle assessment is a tool in need of improvement. Multiple authors have written about its individual problems, but a unified treatment of the subject is lacking. The following literature survey gathers and explains issues, problems and problematic decisions currently limiting LCA’s goal and scope definition and life cycle inventory phases. Main features  The review identifies 15 major problem areas and organizes them by the LCA phases in which each appears. This part of the review focuses on the first 7 of these problems occurring during the goal and scope definition and life cycle inventory phases. It is meant as a concise summary for practitioners interested in methodological limitations which might degrade the accuracy of their assessments. For new researchers, it provides an overview of pertinent problem areas toward which they might wish to direct their research efforts. Results and discussion  Multiple problems occur in each of LCA’s four phases and reduce the accuracy of this tool. Considering problem severity and the adequacy of current solutions, six of the 15 discussed problems are of paramount importance. In LCA’s first two phases, functional unit definition, boundary selection, and allocation are critical problems requiring particular attention. Conclusions and recommendations  Problems encountered during goal and scope definition arise from decisions about inclusion and exclusion while those in inventory analysis involve flows and transformations. Foundational decisions about the basis of comparison (functional unit), bounds of the study, and physical relationships between included processes largely dictate the representativeness and, therefore, the value of an LCA. It is for this reason that problems in functional unit definition, boundary selection, and allocation are the most critical examined in the first part of this review.

铁线莲属研究随记(Ⅴ)

(1)描述了9新种,4新变种;做出了2新等级,1新组合和1新名称。(2)归并了以下拉丁学名： Clematis dioica L．ssp．virginiana(L．)Kuntze var．bahamica Kuntze,C．bahamica (Kuntze) Britton,C．orbic- ulata Correll,C．brasiliana DC．var．laxa St．Hilaire,C．perulata Kuntze,C．barranacae Jones,C．discolor Gardn., C．laxiflora Baker,C．bathiei Lévl．和C．mauritiana Lam．var．sulfurea Viguier &; Perrier。(3)对威灵仙C．chinensis Osbeck的5个变种进行了分类;特产日本的C．fujisanensis Hisauti &; Hara与C.chinensis 极为相近,主要区别在于具较大的花,但有时花与C.chinensis的花同样大,由于区别不大,在本文中被 降级作变种处理;与其近缘、具强烈退化花序、特产华东的C．anhweiensis M．C．Chang也随之被处理为 变种。(4)瑞典学者Johnson在最近出版的铁线莲属专著中将特产西印度群岛东部的C．Flukenetii DC． 归并于特产美国东南部的C．catesbyana Pursh;本文不同意他做出的归并,并列出了这两个种的明显区 别特征,确认后者是一个应该得到承认的独立的种。(5)根据墨西哥标本描述的C．acapulcensis Hook． &; Arn．原知分布于中美一带,而其在南美的居群和一小叶多毛的新变种(var．puberula)过去长期间被误 定为其近缘种C．affinis St．Hilaire;这个混乱在本文中得到澄清,同时,本文给出了这二近缘种的区别 特征。(6)Viguier和Perrier两位学者在上世纪四十年代末研究马达加斯加一带的黄花铁线莲组-怀特铁 线莲亚组(sect．Meclatis subsect．Wightianae)植物时做出了不少错误鉴定：(a)将特产马达加斯加的具三 出复叶的C．mauritiana Lam. var．mauritiana,var．coriacea和C．microcuspis Baker,以及具单叶的C．ac- tinostemmatifolia W．T．Wang均鉴定为分布于非洲大陆的C．simensis Fresen., 并将后者作为分布于亚洲和欧洲的C．orientalis L．的亚种处理;(b)将特产马达加斯加具三出复叶的C．laxiflora Baker和具一回羽状复叶的C．ibarensis Baker鉴定为特产印度南部的C．wightiana Wall.,也将后者作为C．orientalis的亚种处理;(c)将特产科摩罗(Comoros)具二回羽状复叶的C．comoresensis W．T. Wang鉴定为C．brachiata Thunb.,也将后者作为C．orientalis L．的亚种处理;(d)将C．ibarensis Baker(具一回羽状复叶和两性花)这一拉丁学名用在了另一特产马达加斯加具2～3回羽状复叶和单性花、应属于单性铁线莲组sect． Aspidanthera的种(C．rutoides W．T．Wang)之上;(e)将另一特产马达加斯加具一回羽状复叶和单性花、 也属于单性铁线莲组的C．edentata Baker(＝C．insidiosa Baill．)降级作为这两位学者曲解的C．ibarensis Baker的亚种处理;(f)将特产马达加斯加的C．dissecta Baker归并到属于茴芹叶铁线莲组(sect． Pseudanemone)的C．pimpindllifolia Hook．中。此次本文第五部分继去年第一、二部分之后对上述混乱情况做出了完全澄清,并给出了分布于马达加斯加及其邻近岛屿的怀特铁线莲亚组8种植物的检索表;由于C．ibarensis Baker的定义被上述两位学者严重误解,本文根据较多具花、果的标本写出了此种完整、正确的形态描述。     

Take two people—a genetics teaching kit

This easily made kit has proved very effective in teaching genetics to pupils of low ability     

山东南部景观生态对策研究

在对山东南部气候、地貌、土壤、植被等景观生态要素研究的基础上,以地貌和基质为基本线索、以植被为标志建立了该地区的景观生态分类系统．该系统为二级分类系统,包括７个景观型、１７个景观亚型,其中,景观型根据植被（植被型或栽培植被型）划分,景观亚型根据地貌、植被（群系组或栽培组合）划分．以景观亚型或景观亚型的组合为基本单位,以１∶１００万土壤图为基础底图,参考多种比例尺的卫星照片、植被图、土地利用图、地貌图等,编制了山东南部１∶１００万景观生态类型图;在景观生态类型图上量算了各景观亚型的面积．据此详细分析了山东南部稀疏植被景观、常绿针叶林景观、落叶阔叶林景观、旱地作物景观、水旱轮作景观、湖泊景观等主要景观型的生态问题,提出了相应的生态对策     

Random field models for fitness landscapes

 In many cases fitness landscapes are obtained as particular instances of random fields by randomly assigning a large number of parameters. Models of this type are often characterized reasonably well by their covariance matrices. We characterize isotropic random fields on finite graphs in terms of their Fourier series expansions and investigate the relation between the covariance matrix of the random field model and the correlation structure of the individual landscapes constructed from this random field. Correlation measures are a good characteristic of “rugged landscapes” models as they are closely related to quantities like the number of local optima or the length of adaptive walks. Our formalism suggests to approximate landscape with known autocorrelation function by a random field model that has the same correlation structure. Received: 10 November 1995 / Revised version: 19 February 1996     

On comparison of mixture models for closed population capture-recapture studies

Summary .  A mixture model is a natural choice to deal with individual heterogeneity in capture–recapture studies. Pledger (2000, Biometrics 56, 434–442; 2005, Biometrics 61, 868–876) advertised the use of the two-point mixture model. Dorazio and Royle (2003, Biometrics 59, 351–364; 2005, Biometrics 61, 874–876) suggested that the beta-binomial model has advantages. The controversy is related to the nonidentifiability of the population size ( Link, 2003 , Biometrics 59, 1123–1130) and certain boundary problems. The total bias is decomposed into an intrinsic bias, an approximation bias, and an estimation bias. We propose to assess the approximation bias, the estimation bias, and the variance, with the intrinsic bias excluded when comparing different estimators. The boundary problems in both models and their impacts are investigated. Real epidemiological and ecological examples are analyzed.