A classification of the Ericaceae: subfamilies and tribes

The variation shown by 60 characters (morphological, anatomical, embryological, chemical and cytological) is tabulated for the whole of the Ericaceae. The reliability of the characters and the observations on them are discussed, and it is emphasized that many characters are difficult to use because they are rarely restricted to one taxon. Six subfamilies are recognized. Within the Rhododendroideae seven tribes are recognized, the monogeneric Daboecieae being new; Epigaea is transferred to the Rhododendroideae from the Andromedeae and Diplarche from the Diapensiaceae. Calluna is placed in a new monotypic tribe within the Ericoideae. The extended Vaccinioideae includes the Arbutoideae; five tribes are recognized, of which the Enkiantheae and Cassiopeae are new. The Pyroloideae and Monotropoideae are left unchanged: a new subfamily, the Wittsteinioideae, includes the deviant monotypic genus Wittsteinia. A key to subfamilies, and to genera of the Pyroloideae, Rhododendroideae and superior-ovaried Vaccinioideae is given.     

A general test of association for quantitative traits in nuclear families

High-resolution mapping is an important step in the identification of complex disease genes. In outbred populations, linkage disequilibrium is expected to operate over short distances and could provide a powerful fine-mapping tool. Here we build on recently developed methods for linkage-disequilibrium mapping of quantitative traits to construct a general approach that can accommodate nuclear families of any size, with or without parental information. Variance components are used to construct a test that utilizes information from all available offspring but that is not biased in the presence of linkage or familiality. A permutation test is described for situations in which maximum-likelihood estimates of the variance components are biased. Simulation studies are used to investigate power and error rates of this approach and to highlight situations in which violations of multivariate normality assumptions warrant the permutation test. The relationship between power and the level of linkage disequilibrium for this test suggests that the method is well suited to the analysis of dense maps. The relationship between power and family structure is investigated, and these results are applicable to study design in complex disease, especially for late-onset conditions for which parents are usually not available. When parental genotypes are available, power does not depend greatly on the number of offspring in each family. Power decreases when parental genotypes are not available, but the loss in power is negligible when four or more offspring per family are genotyped. Finally, it is shown that, when siblings are available, the total number of genotypes required in order to achieve comparable power is smaller if parents are not genotyped.     

Bioethics, vulnerability, and protection

What makes individuals, groups, or even entire countries vulnerable? And why is vulnerability a concern in bioethics? A simple answer to both questions is that vulnerable individuals and groups are subject to exploitation, and exploitation is morally wrong. This analysis is limited to two areas. First is the context of multinational research, in which vulnerable people can be exploited even if they are not harmed, and harmed even if they are not exploited. The type of multinational research likely to raise the most ethical concerns is that in which the investigators or sponsors are from a powerful industrialised country or a giant pharmaceutical company and the research is conducted in a developing country. Second is the situation of women, who are made vulnerable in cultural settings or in entire countries in which they are oppressed and powerless. In the face of cultural values and practices, or governmental policies, these women suffer serious consequences for their health and even lives. Examples are provided, and it is suggested that in some cases vulnerable individuals can be harmed but not exploited. On the positive side, recent developments reveal a new awareness of exploitation and efforts to enhance the ability of developing countries to protect themselves and their citizens from exploitation at the hands of powerful sponsors of research. In addition, human rights principles are increasingly being used to monitor the actions (or inaction) of governments regarding women's reproductive rights and vulnerability with respect to HIV/AIDS, and to take remedial actions.     

Ecology of nematophagous fungi: vertical distribution in a deciduous woodland

Summary The distribution of nematophagous fungi in soil collected from a deciduous woodland is compared to various biotic and abiotic soil factors. The microfungi are isolated at all depths down to a maximum of 35 cm. Predators forming constricting rings, adhesive branches and adhesive knobs are restricted to the upper litter and humus layers. The net forming predators and endoparasites are isolated at all depths, although they are significantly more abundant in the lower mineral rich soils. A much greater species diversity of nematophagous fungi is recorded in the upper organic zones.Preliminary soil analysis indicates thatCephalosporium balanoides is independent of all soil variables, while predators able to form traps spontaneously are restricted to the organic soils which are rich in nematodes. Non-spontaneous trap forming predators, which are excellent saprophytes, are isolated from the deeper soils which are low in nutrients. The ecological significance of these results is discussed.     

The systematics and adaptations of some Papuan microhylid frogs which live underground

A taxonomic, anatomical and behavioural account is given of some burrowing microhylid frogs from New Guinea. Six species belonging to four genera are dealt with, of these four are described as new species. Two genera are removed from synonomy to accommodate four of the burrowing species. Histological and anatomical modifications to the head, which are associated with head-first burrowing, are described. The calls of the male frogs are described in detail and attention is drawn to the similarity of calls made by all burrowing species. This is discussed in relation to the problems of sound transmission below ground.     

Multilocus selection in subdivided populations I. Convergence properties for weak or strong migration

The dynamics and equilibrium structure of a deterministic population-genetic model of migration and selection acting on multiple multiallelic loci is studied. A large population of diploid individuals is distributed over finitely many demes connected by migration. Generations are discrete and nonoverlapping, migration is irreducible and aperiodic, all pairwise recombination rates are positive, and selection may vary across demes. It is proved that, in the absence of selection, all trajectories converge at a geometric rate to a manifold on which global linkage equilibrium holds and allele frequencies are identical across demes. Various limiting cases are derived in which one or more of the three evolutionary forces, selection, migration, and recombination, are weak relative to the others. Two are particularly interesting. If migration and recombination are strong relative to selection, the dynamics can be conceived as a perturbation of the so-called weak-selection limit, a simple dynamical system for suitably averaged allele frequencies. Under nondegeneracy assumptions on this weak-selection limit which are generic, every equilibrium of the full dynamics is a perturbation of an equilibrium of the weak-selection limit and has the same stability properties. The number of equilibria is the same in both systems, equilibria in the full (perturbed) system are in quasi-linkage equilibrium, and differences among allele frequencies across demes are small. If migration is weak relative to recombination and epistasis is also weak, then every equilibrium is a perturbation of an equilibrium of the corresponding system without migration, has the same stability properties, and is in quasi-linkage equilibrium. In both cases, every trajectory converges to an equilibrium, thus no cycling or complicated dynamics can occur.      

Tail effects on yaw stability in birds

Bird tails, which are an aerodynamic surface in the horizontal plane, are treated with regard to their effects on yaw stability. Reference is made to wings of very small aspect ratio similar to the values of bird tails in order to identify features which are significant for the aerodynamic yawing moment characteristics due to sideslip. It is shown that there are yawing moments of considerable magnitude for this aspect ratio region. Furthermore, the lift coefficient, which also exerts an influence, is included in the treatment of yaw stability. To show more concretely the addressed effects for birds, the yawing moment characteristics of the wing-tail combination of a pigeon, which is considered as a representative example, are treated in detail. For this purpose, a sophisticated aerodynamic method capable to deal with the mutual flow interactions between the tail and the wing is used to compute results of high precision. The yawing moment characteristics of the pigeon wing-tail combination with respect to the sideslip angle and the lift coefficient are determined, with emphasis placed on the contribution of the tail. It is shown that there is a significant contribution of the tail to yaw stability. The findings of this paper on the contribution of the tail to the yawing moment characteristics are supported by an evaluation of existing experimental data. Furthermore, the physical mechanisms are considered which are the reasons for the stabilizing role of the tail. These effects concern the contribution of the drag acting at the tail to the yawing moment. In addition, it is shown that extended legs and feet, when exposed to the airflow, can contribute to yaw stability.     

Isostaticity and controlled force transmission in the cytoskeleton: A model awaiting experimental evidence

A new model is proposed for force transmission through the cytoskeleton (CSK). A general discussion is first presented on the physical principles that underlie the modeling of this phenomenon. Some fundamental problems of conventional models--continuous and discrete--are examined. It is argued that mediation of focused forces is essential for good control over intracellular mechanical signals. The difficulties of conventional continuous models in describing such mediation are traced to a fundamental assumption rather than to their being continuous. Relevant advantages and disadvantages of continuous and discrete modeling are discussed. It is concluded that favoring discrete models is based on two misconceptions, which are clarified. The model proposed here is based on the idea that focused propagation of mechanical stimuli in frameworks over large distances (compared to the mesh size) can only occur when considerable regions of the CSK are isostatic. The concept of isostaticity is explained and a recently developed continuous isostaticity theory is briefly reviewed. The model enjoys several advantages: it leads to good control over force mediation; it explains nonuniform stresses and action at a distance; it is continuous, making it possible to model force propagation over long distances; and it enables prediction of individual force paths. To be isostatic, or nearly so, CSK networks must possess specific structural characteristics, and these are quantified. Finally, several experimental observations are interpreted using the new model and implications are discussed. It is also suggested that this approach may give insight into the dynamics of reorganization of the CSK. Many of the results are amenable to experimental measurements, providing a testing ground for the proposed picture, and generic experiments are suggested.     

An extension of the transmission disequilibrium test incorporating imprinting

The recombination rates in meioses of females and males are often different. Some genes that affect development and behavior in mammals are known to be imprinted, and >1% of all mammalian genes are believed to be imprinted. When the gene is imprinted and the recombination fractions are sex specific, the conventional transmission disequilibrium test (TDT) is shown to be still valid for testing for linkage. The power function of the TDT is derived, and the effect of the degree of imprinting on the power of the TDT is investigated. It is learned that imprinting has little effect on the power when the female and male recombination rates are equal. On the basis of case-parents trios, the transmissions from the heterozygous fathers/mothers to their affected children are separated as paternal and maternal, and two TDT-like statistics, TDT(p) and TDT(m), are consequently constructed. It is found that the TDT(p) possesses a higher power than the TDT for maternal imprinting genes, and the TDT(m) is more powerful than the TDT for paternal imprinting genes. On the basis of the parent-of-origin effects test statistic (POET), a novel statistic, TDT incorporating imprinting (TDTI) is proposed to test for linkage in the presence of linkage disequilibrium, which is shown to be more powerful than the TDT when parent-of-origin effects are significant but slightly less powerful than the TDT when parent-of-origin effects are negligible. The validity of the TDT and TDTI is assessed by simulation. The power approximation formulas for the TDT and TDTI are derived and the simulation results show that they are accurate. The simulation study on power comparison shows that the TDTI outperforms the TDT for imprinted genes. The improvement can be substantial in the case of complete paternal/maternal imprinting.     

The microbiology of metalworking fluids

Metalworking fluids (MWFs) are complex mixtures of chemicals and are indispensable materials in industry. They are used as cooling and lubricating agents in different machining process such as grinding, milling, and cutting. The quality of MWFs is affected by physical, chemical, and microbial contaminates. In particular, MWFs are highly vulnerable to microbial contamination, which may act both as potential pathogens and deteriorgens. Microbial contamination is of major concern due to potential health hazards such as skin dermatitis and hypersensitivity pneumonitis. The contaminated MWFs can exhibit high degrees of microbial loading, ranging from 10(4) to 10(10) colony-forming units (CFU)/ml. Wide varieties of microorganisms are reported to colonize MWFs. Traditional culturing techniques are not only laborious and time consuming but also underestimate the actual distribution of the microorganisms present in the contaminated MWFs. Therefore, rapid molecular methods such as real-time PCR and fluorescent in situ hybridization are implemented to monitor the microbial load. In industry, biocides are presently used to control microbial contamination. However, it has its own disadvantages and therefore, in recent years, alternative methods such as UV irradiation were evaluated to reduce microbial contamination in MWFs. Microbes inhabiting the MWF are also capable of forming biofilm which is detrimental to the MWF system. Biofilm is resistant to common disinfectant methods, and thus further research and development is required to effectively control its formation within MWF systems. This review is intended to discuss the overall microbiological aspects of MWF.     

一种基于Wilson-Cowan双节点耦合振子模型的图像增强方法

针对模拟大脑节律现象的Wilson-Cowan双节点耦合振子模型,选取满足该模型产生极限环振荡条件的参数,采用连续灰度阶图像块作为输入,兴奋性亚群节点响应作为图像增强的输出,做出刺激响应曲线,发现该曲线与图像处理领域中用于图像增强的Gamma校正曲线相似,说明Wilson-Cowan双节点耦合振子模型可以作为一种新的图像增强方法,同时也为基于Gamma校正曲线的图像增强提供了一种神经机制。将新方法与Retinex算法做对比,表现出了更好的图像增强性能。     

The loss in power when the test of differential expression is performed under a wrong scale.

One of the most common and important goals of microarray studies is to identify genes that are differentially expressed between cells of different conditions. T-test and ANOVA models on the expression data are common practices to gauge the significance of the observed difference in expression levels. Transformation of the microarray data is often applied in order to satisfy the model assumptions being entertained. However, the distributional properties of the expression are gene specific, and it is impractical to find a single transformation that is universally optimal for all the genes. This difficulty results in the situation that some genes have to violate the assumptions of the model (e.g., homogeneity in variance, normality). It is thus the interest of this paper to evaluate the impact on the inference of differential expression when the test is performed under an inappropriate scale. Particularly, we quantitatively assess the loss of power when the test is performed under a wrong scale. Normal distribution and log-normal distribution of the expression data are considered. The loss in power is investigated in two scenarios: a transformation is misused, or a transformation fails to be applied. Log transformation and power transformation are particularly considered due to the fact that Box-Cox types of transformation are commonly used in practice. The impact of using a wrong scale is investigated analytically and based on simulations. The loss in power is assessed both as a function of the degree to which the assumptions are violated and as a function of the effect size. Simulations are conducted to quantitatively assess the power loss when tests are performed under a wrong scale. A public experimental microarray dataset is used to illustrate the impact of transformation on the results of testing differential expression. The results show that the loss of power is a function of CV and fold-change (effect size). The loss in power depends on the true model and on how severely the assumptions are violated.     

Admixture studies in Latin America: from the 20th to the 21st century

The present study is a review of admixture studies in Latin America, an interesting subject because of the unique history of the area, in which populations from 3 different origins had contact and intercrossed. The most often used methods of analysis of admixture in Latin America and some problems related to them, such as the determination of the parental populations and selection of genetic markers, are briefly reviewed. Several sources of data for admixture studies (surnames, quantitative traits, proteins, and molecular information) are summarized. The results obtained using protein systems and blood groups, the most often used markers in Latin America, are considered. They are classified according to their application in 3 groups of populations: urban centers, native Americans, and African-descended subjects. The data show that almost every population is dihybrid or trihybrid, and when African influence is not detected, it is probably due more to the method than to an absence of that contribution. A special section is dedicated to the direction of gene flow, and results about directional mating based on mtDNA, Y-chromosome, and nuclear DNA or proteins are also given. From these studies it is possible to conclude that Amerindian admixture came mainly from female lineages, but it is difficult to establish what happened with the African contribution. A last subject considered is the relation between interethnic crosses and diseases; it is easy to analyze that relation when the pathological condition is related to a unique allele, but when complex diseases are considered, the results are not as clear because of the influence of nongenetic factors. Finally, the perspectives for admixture studies in the 21st century are considered, and some attempts to predict their future in Latin America are made.     

Evidence-based care: 2. Setting guidelines: how should we manage this problem?

There are four steps in determining how to manage a clinical problem. The first is to formulate questions that are answerable; the second is to locate and synthesize the evidence needed to answer the questions; the third is to estimate the expected benefits, harms and costs of each option based on the evidence; and the fourth is to judge the relative value of the expected outcomes to conclude whether the benefits are worth the harms and costs. It is impractical to repeat these steps for every clinical decision. Therefore, implicitly or explicitly, physicians rely on guidelines, "rules" that simplify decision making about complex problems. If the methods used to develop a guideline are not explicit it is difficult or impossible to know how much confidence to place in it. Therefore, for common and important clinical problems, physicians should rely on guidelines that are systematically developed using explicit methods.     

Plant pathogenic RNAs and RNA catalysis.

The rolling circle replication of small circular plant pathogenic RNAs requires a processing step to convert multimeric intermediates to monomers which are then circularized. Eleven such RNAs are known so far, two are viroids, one is viroid-like and the remainder are satellite RNAs dependent on a helper virus for replication. The processing step is RNA-catalysed in all cases, at least in vitro. All plus forms of these RNAs self-cleave via the hammerhead structure whereas only eight of the minus RNAs self-cleave, five via the hammerhead structure and three via the hairpin structure. There are about 20 other viroids where the processing mechanism has yet to be determined but they are likely candidates for a new type of self-cleavage reaction which is predicted to be conserved in all these viroids. Hepatitis delta RNA is the only circular pathogenic RNA known to self-cleave in the animal kingdom. It is feasible that more single-stranded circular pathogenic RNAs are waiting to be discovered and these could be prospective for new types of self-cleavage reactions.     

Stress-Induced Translational Control in Potato Tubers May Be Mediated by Polysome-Associated Proteins

Potato tubers exhibit distinct responses to wounding and hypoxia that include selective translation of stress-induced mRNAs. Newly synthesized wound-response mRNAs are bound to polysomes, whereas preexisting mRNAs are displaced and degraded. mRNAs that are induced and translated during hypoxic conditions are bound to ribosomes as expected. However, preexisting wound-response mRNAs whose translation is inhibited during hypoxia remain bound to polysomes, indicating that there are at least two distinct mechanisms by which translation is regulated in response to stress conditions. A 32-kD phosphoprotein is associated with polyribosomes from wounded tubers. This protein remains polysome bound as long as wound-response mRNAs are present, even during hypoxia when these mRNAs are no longer translated. However, association of the 32-kD protein with polysomes is not elicited by hypoxic stress alone. The kinase that phosphorylates this protein is active only for the first 24 hr after wounding and is not active during periods of hypoxia. This protein may mediate recognition of the wound-response mRNAs by ribosomes.     

Incorporating retrospective data into an analysis of time to illness

For studies of time to illness, the prospective cohort study is, in general, the method of choice. When the time of origin is known for all subjects, then a prevalent cohort study in which individuals are recruited at variable times after the start of the illness process is a suitable alternative. Often, when a prevalent cohort is being formed, data may also be available on individuals who are already ill but are alive. The incorporation of such data, which is practically appealing to many researchers, is discussed. The nature of the required assumptions and the need also to model the illness to death process are illustrated. Full likelihood and pseudolikelihood techniques are outlined and compared with each other and with the use of only prevalent cohort data in a small simulation study. An example based on an HIV seroconverter study is discussed for illustration. The full likelihood method is seen to be too complex for general application. The use of pseudolikelihoods is easier to implement. If there is reliable information on initiating event times and recruitment strategies are well defined, then the incorporation of retrospective data may be beneficial. In other situations, their incorporation is too problematic to be recommended.*To whom correspondence should be addressed.     

Play-like behaviour: An essay in speculative ethology

It is claimed that certain processes of individual behaviour and of interaction between individuals run parallel. Such parallels are seen along three axes: antagonism-coordination, constriction-expansion and neutral-play-like. Characteristics of ritualized behaviour and play are analysed and the two categories of behaviour are compared in detail. They are shown to differ largely in degree of expansion. They also differ along the antagonism-coordination axis. Both are play-like. A theory comprising both ritualized behaviour and play is attempted. The concept of field interaction is introduced. The physical theory of elect ro-magnetism is used as a conceptual model. Positive and problematic aspects of the theory are discussed: Is the behavioural field polarised or not? The relationship between aggression and play-like behaviour is considered, both as a motivational problem and in phylogenetic perspective. Some limits to the theory are indicated. Relationships of the theory to some other theories are briefly discussed.     

SD大鼠与巴马小型猪的皮肤组织学比较

目的研究及观察SD大鼠和巴马小型猪皮肤的正常比较组织学。方法取SD大鼠和巴马小型猪不同部位的皮肤进行石蜡切片、HE染色,光学显微镜观察。结果两种动物的皮肤组织学结构在以下方面存在着显著差异：1.SD大鼠的毛囊成簇分布,平均3～9成群,而巴马小型猪的毛囊较稀少;2.SD大鼠表皮较薄,没有透明层,基底细胞缺乏异质性,真皮与表皮连接面平坦,没有皮钉;而在巴马小型猪皮肤表皮和真皮连接区,有上下交错的表皮皮钉和真皮乳头;3.SD大鼠的真皮结构相对松散,真皮血管系统不发达,而巴马小型猪皮肤的真皮网织层和乳头层交界的地方,水平分布着很多的浅表小静脉和小动脉丛,这种血管分布的方式与人类皮肤中的血管分布极为类似;4.SD大鼠的汗腺只局限于足垫的皮肤,汗腺上皮只有一种细胞类型,腺细胞呈立方形或矮柱状,胞核圆形,导管短而弯曲,由两层上皮细胞组成。而巴马小型猪皮肤的汗腺是顶泌汗腺,分布于真皮和脂肪相接的真皮深层,分泌部为粗管,管腔大,盘曲成团。腺细胞呈立方形或扁平,胞核圆形或长梭形。腺细胞与基膜之间也有肌上皮细胞。导管较细而直,开口于毛囊上段。     

A model of the basal ganglia in voluntary movement and postural reactions

A basal ganglia central pattern generator (CPG) is developed and its role in voluntary movements on the ground and postural reactions on a disturbed platform are studied and analysed by simulation. Biped dynamics and platform kinematics are utilised. The effects of agonist–antagonist muscular co-activation and joint stiffness are formulated. The implementation of the necessary counter-manoeuvres for maintaining balance and postural stability is studied. A control strategy, applicable to large systems, is formulated. The biped manoeuvres and transitions terminate in pre-specified intervals of time. Gravity is included and compensated for. Certain voluntary and postural adjustment strategies are the same but are initiated differently. Further experimental/computational research may identify the central nervous system and sensory paths that lead to the CPG. All actuator forces linearly evolve in time from their original values to their terminal values. There are no central continuous feedback loops present. Monitoring and sensing, however, are ongoing. The counter-manoeuvres are based on learned human-like voluntary movements that are triggered by the disturbance. The required central inputs to the musculoskeletal system are designed in the CPG. A functional structure for the CPG is proposed. The effect of certain disorders and malfunctions of the CPG are studied by simulation.