On mammalian sperm dimensions

Data on linear sperm dimensions in mammals are presented. There is information on a total of 284 species, representing 6.2% of all species; 17.2% of all genera and 49.2% of all families have some representation, with quantitative information missing only from the orders Dermoptera, Pholidota, Sirenia and Tubulidentata. In general, sperm size is inverse to body mass (except for the Chiroptera), so that the smallest known spermatozoa are amongst those of artiodactyls and the largest are amongst those of marsupials. Most variations are due to differences in the lengths of midpiece and principal piece, with head lengths relatively uniform throughout the mammals.     

Living in three dimensions

Research focused on deciphering the biochemical mechanisms that regulate cell proliferation and function has largely depended on the use of tissue culture methods in which cells are grown on two-dimensional (2D) plastic or glass surfaces. However, the flat surface of the tissue culture plate represents a poor topological approximation of the more complex three-dimensional (3D) architecture of the extracellular matrix (ECM) and the basement membrane (BM), a structurally compact form of the ECM. Recent work has provided strong evidence that the highly porous nanotopography that results from the 3D associations of ECM and BM nanofibrils is essential for the reproduction of physiological patterns of cell adherence, cytoskeletal organization, migration, signal transduction, morphogenesis, and differentiation in cell culture. In vitro approximations of these nanostructured surfaces are therefore desirable for more physiologically mimetic model systems to study both normal and abnormal functions of cells, tissues, and organs. In addition, the development of 3D culture environments is imperative to achieve more accurate cell-based assays of drug sensitivity, high-throughput drug discovery assays, and in vivo and ex vivo growth of tissues for applications in regenerative medicine.     

Errors in three dimensions

Now that some protein X-ray structures have been proved to contain major errors, the question of the precision of 3-dimensional structures is taken seriously by crystallographers and NMR spectroscopists. Errors which cannot be avoided during model building in electron density maps, should correct themselves during crystallographic refinement, and the precision of the refined model should reach 0.15 to 0.25 A depending on the resolution of the data. Independent estimates based on homologous protein structures confirm that better than 0.5 A precision is commonly achieved, at least for C alpha and main chain atoms. The precision of NMR structures is less easily evaluated, but it should be better than 2 A when a sufficient number of NOE distance constraints are available. One may deplore the fact that not all published structures meet these standards, but possible errors should not be an excuse for not depositing atomic co-ordinates in data banks.     

Spatiotemporal dimensions of community assembly

Ecological communities are assembled through a series of multiple processes, including dispersal, abiotic and biotic filtering, and ecological drift. Although these assembly processes act in concert to structure local communities, their relative importance is considerably variable among study systems. While such contingency of community assembly has been widely appreciated, the empirical and theoretical evidence is scattered around in the literature, and few efforts have been made to synthesize it. In this mini-review, we summarize the accumulated evidence of the context-dependency of community assembly rules, to reach a rough generalization of the contingency. Specifically, we argue that spatial and temporal dimensions can serve as general axes that regulate the relative importance of assembly processes. To this end, we synthesize the current understanding of how the relative importance of multiple assembly processes changes with spatial scales and complexity, and with time in the long and short terms. This review concludes that spatial and temporal dimensions can be common currencies of community assembly rules that are shared across various systems.     

Body dimensions of Indian housewives

Anthropometric dimensions of Indian housewives have been measured from the viewpoint of architectural and product design ergonomics. Altogether, 79 different body dimensions were measured on 147 urban housewives of age range varying between 21 to 56 years. The average stature and weight of Indian housewives as observed in this study were 153.2 cm (SD +/- 5.7) and 55.1 kg (SD +/- 9.7), respectively. Average values along with 5th and 95th percentile values for all measurements have been determined. Values were compared with other Indian studies. A correlation between the body height, weight, and other measurements were obtained with the help of a PDP 11/23 microcomputer. Based on the existing data ratio scale relationships between the body height and other measurements of Indian women were determined. An anthropometric data, pack is presently lacking; therefore, the findings herein can be used while determining household workplace layouts, evaluating area specifications, determining work-surface heights, clearances, reach, etc. A similar study on a larger population size for Indian women has been suggested for establishing national standards.     

Transmission of human craniofacial dimensions

The transmissibilities of 11 human craniofacial dimensions are estimated by path analysis based upon familial correlations obtained in four different populations. Estimates from both the individual populations and from pooled correlations indicate that the observed variation in craniofacial dimensions is determined by genetic and nongenetic factors in roughly equal measure (.45 less than t 2 less than .60). These results implicate the possibility of complex gene-environment and gene-gene interactions in the development of the size and shape of the head and face and call for more detailed familial studies of these traits. This additional complexity further suggests the need for caution in interpreting such metrical variation, especially from a diagnostic or classificatory viewpoint.     

The international dimensions of neuroethics

Neuroethics, in its modern form, investigates the impact of brain science in four basic dimensions: the self, social policy, practice and discourse. In this study, we analyzed a set of 461 peer-reviewed articles with neuroethics content, published by authors from 32 countries. We analyzed the data for: (1) trends in the development of international neuroethics over time, and (2) how challenges at the intersection of ethics and neuroscience are viewed in countries that are considered developed by International Monetary Fund (IMF) standards, and in those that are developing. Our results demonstrate a steady increase in global participation in neuroethics from 1989 to 2005, characterized by an increase in numbers of articles published specifically on neuroethics, journals publishing these articles, and countries contributing to the literature. The focus from all countries was on the practice of brain science and the amelioration of neurological disease. Indicators of technology creation and diffusion in developing countries were specifically correlated with increases in publications concerning policy implications of brain science. Neuroethics is an international endeavor and, as such, should be sensitive to the impact that context has on acceptance and use of technological innovation.     

Age changes of skull dimensions

At cranial level, external apposition during ageing has been postulated by some authors. In longitudinal studies, a gradual increase of cranial diameters has been shown by cephalometry (Kendrick et al. 1967) or by lateral radiography (Israel 1968, 1970). However, these results are contested at methodological level by other longitudinal studies (Tallgren 1974). It is the aim of this study to analyse, in a cross-sectional sample, the effects of senescence on several cephalic dimensions. A series of skulls of known age and sex has been selected for this purpose.     

Immunofluorescent flow cytometry inN dimensions

The problem of the simultaneous use in flow cytometry ofN>2 antibodies in conjunction with two fluorochromes was investigated. Theoretical analysis led to a labeling procedure and reconstruction formula that allowN-dimensional labeling distributions to be obtained from two-dimensional fluorescence distributions. The general problem ofM≥2 fluorochromes andN>M antibodies was shown to be reducible to the case of two fluorochromes. The method was tested by a triple labeling analysis of murine thymocytes.