Estimation of Distances and Variances in Bookstein's Landmark Model

Planar random figures can be described by series of landmarks. Bookstein's model assumes that the landmarks result from independent individual fluctuations around fixed fictive landmark centres. The aim of this paper is to estimate the distances between the centers and the variances of fluctuations around them. Furthermore, two new shape variable estimators are suggested and compared with an estimator of Bookstein.     

Tubular hand bone growth during the latter half of the prenatal period: an allometric analysis

The growth of the 19 tubular hand bones from fetal months 5 to 9 was studied by the allometric method. The hand bones were carefully dissected under a low power stereoscopic microscope. The length and breadth of all bones was found to be monophasic in relation to crown-rump length. In general, maximum bone and ossified shaft lengths in the same row group demonstrate similar allometric coefficients. The specific growth rate of ossified shaft length for all fetal hand bones is greater than the growth rate of maximum length. The highest allometric coefficients for both maximum length and ossified shaft length were obtained from the middle phalanges. The shape of the metacarpals and distal phalanges becomes thinner, while the other bones become thicker or maintain their length-breadth ratio. The relative growth pattern of the first proximal phalanx differed from the middle phalangeal group of the other digits. This suggests that current nomenclatures for the three bones of the pollex is appropriate.     

Helical growth and the curved shape of Vibrio cholerae

The curved, comma, or bent shape of Vibrio cholerae is attributed to, and explained by, the normal helical growth of the cell. The comma-like shape of V. cholerae is not due to an asymmetrical positioning of peptidoglycan such that some chains of peptidoglycan are placed so they are more spread out on one side of the cell and squeezed together on the other side.     

原木形状分段描述方法的数学描述理论研究

为制材、木材检尺等特殊行业需要的原木数控检测提供数学描述理论,提出的这些理论将为数控检测的数学模型建立提供具体的数学方法,为原木形状的视频再现提供编程的数学工具．本文提出的理论还将为数控下锯法提供理论依据,与制材工艺结合起来,将使传统原木检测数字化,为科学管理原木和数字化统计与检尺控制提供了理论,本文是木材工业中用数学描述检测过程的开始．通过本文的研究,可以推进木材工业检测过程数学描述研究的开展．     

Assessment of cell proportions during regeneration ofDileptus anser (Ciliata)

Summary Following transection ofDileptus regulation of cell shape and cortical pattern was studied during regeneration in an attempt to understand the interrelations of these two regulation processes. The cell ofDileptus consists of two regions, proboscis and trunk, with the oral structures marking the border between them. The isolated proboscis is able to reorganize into a complete and correctly proportioned organism and the course of this reorganisation has been observed.Correct cell proportions take more than 24h to be established. Three hours after the operation the new border between proboscis and trunk is formed. Initially, the proportions of the cell are far from normal; moreover, they can temporarily change towards a more abnormal state. This indicates that the localisation of the border between the two cell regions and the assessment of final cell proportions are separate phenomena possibly controlled by different mechanisms.     

Diversity emergence and dynamics during primary immune response: a shape space,physical space model

A computational model of the dynamics of diversity among T-cell receptors and MHC: peptide complex molecules is presented. We propose a method by which individual immune systems may evolve effcient or ineffcient states as a result of T-cell receptor crossreactivity as well as genetic variation among pathogens. By combining shape space and physical space models, valuable insight is obtained into how immune system-wide state is, in large part, determined by localised space dynamics. In the model, system-wide state also informs local dynamics, especially in the lymphatic system during primary immune response. The process by which similar initial infection conditions across individuals may result in highly variable end states (a phenomenon observed in the clinical context) is modelled. Our results show that activity alone is not a good indicator of infection suppression or removal. In this work, we postulate that successful viral clearance is characterised by broad T-cell receptor activation (in shape space), and results in low average concentration levels of activated cytotoxic lymphocyte cells.     

Statistical study of sexual dimorphism in the human fetal sciatic notch

Whether human fetal skeletal remains exhibit sexual dimorphism has been the subject of considerable debate. Most attention in this debate has focused on the greater sciatic notch of the ilium, since it is a gross morphological characteristic with known sex differences in the adult and is easily seen in fetal skeletal remains. Unfortunately, previous traditional morphometric analyses of the fetal sciatic notch have led to ambiguous results. The purpose of this study is to determine whether differences between the sexes can be discerned when modern morphometric techniques are applied to the fetal sciatic notch. Photographs of the ventral side of 133 fetal ilia of known age and sex from the Trotter Collection of Washington University were digitized, and the trace coordinates used for all subsequent analyses. The results of the analysis demonstrate that there is significant sexual dimorphism in the anterior to posterior location of the maximum depth of the sciatic notch, but that the depth of the notch itself is not dimorphic. While there is significant sexual dimorphism in the shape of the sciatic notch, the amount of overlap between males and females is too great for the sciatic notch to be used as a reliable indicator of sex. © 1995 Wiley-Liss, Inc.     

Glial shape and cytoskeletal protein synthesis

We investigated whether the shape of astroglial derived cells influences the expression of cytoskeletal proteins. In reaggregating cultures GFAP, vimentin and actin synthesis was approximately 52%, 50% and 37% the level found in monolayer cultures, respectively. Monolayer cultures consisted of polygonal shaped cells adhering to plastic, while reaggregating cultures were comprised of round cells growing in a suspension like culture. Additionally, human glioma cells induced to grow as round cells on poly-2-hydroxyethyl methacrylate (polyhema) coated plastic exhibited a level of GFAP synthesis that was approximately 20% the level displayed by polygonal shaped cells grown on uncoated plastic. Glioma cells initially grown on a polyhema surface and replated onto uncoated plastic were capable of reinitiating GFAP synthesis. Thus, aterations in the synthesis of GFAP and other cytoskeletal proteins can occur when astrocytes change their shape.     

Ontogenetic variability in the external morphology of monkey goby, Neogobius fluviatilis (Pallas, 1814) and its relevance to invasion potential

In the previous decade, four species of non-native gobies have invaded the middle section of the river Danube and its tributaries. An effective tool for understanding biological invasions is the evaluation of various biological traits (morphological, life history, ontogenetic) within an epigenetic context. The present study examines the external morphology of monkey goby Neogobius fluviatilis (Pallas, 1814) from the mouth of the River Hron, the morphological differences among three goby species (monkey, bighead and round) and the relevance of these differences for invasive potential. Monkey goby reach their definite phenotype very early in their ontogeny and thus represent a strongly precocial (specialized) species with direct development. The morphological differences between monkey and two other goby species also reflect its strong specialization for sandy substrata and smaller prey types. Thus, monkey goby are not expected to spread to new areas as fast as the round and bighead gobies, and their distribution is likely to be limited to sandy and/or sandy-gravel substrata. If this assumption is correct, then the potential adverse impact of monkey goby on native fauna or even ecosystem is likely to be less than that of the bighead and round gobies. Handling editor: K. Martens     

Movement of sodium into human platelets

Addition of ADP induces platelets in plasma to undergo shape change from a disc to a spiny sphere and to develop adhesiveness, i.e. to aggregate. The aggregation of human platelets by ADP is associated with a net uptake of Na⁺. The present experiments demonstrate that the induction of shape change by ADP in acidified or EGTA-treated plasma conditions which inhibit aggregation, is also associated with a movement of Na⁺ into platelets. When ADP-induced platelet shape change and aggregation is inhibited by prostaglandin E₁ Na⁺ uptake is also blocked. Platelets aggregated by epinephrine do not take up Na⁺. In a manner analogous to the effect of ADP, polylysine also induces Na⁺ uptake during aggregation. Vasopressin, in a manner analogous to epinephrine, induces aggregation without Na⁺ uptake. The increase in platelet Na⁺ resulting from ouabain inhibition of Na⁺ efflux induces an increase in the aggregation response to ADP and to epinephrine.     

Modeling protein-mediated morphology in biomembranes

The equilibrium theory for lipid membranes is used to describe the structure of nuclear pores and the membrane shapes accompanying endocytosis. The commonly used variant of the theory contains a fixed parameter called the spontaneous curvature which accounts for asymmetry in the bending response of the membrane. This is replaced here by a variable distribution of spontaneous curvature representing the influence of attached proteins. The required adjustments to the standard theory are described and the resulting model is applied to the study of membrane morphology at the cites of protein-assisted nuclear pore formation and endocytosis.     

Perception of shape-from-motion in macaque monkeys and humans

Motion is one of the most efficient cues for shape perception. We conducted behavioral experiments to examine how monkeys perceive shapes defined by motion cues and whether they perceive them as humans do. We trained monkeys to perform a shape discrimination task in which shapes were defined by the motion of random dots. Effects of dot density and dot speed on the shape perception of monkeys were examined. Human subjects were also tested using the same paradigm and the test results were compared with those of monkeys. In both monkeys and humans, correct performance rates declined when density or speed of random dots was reduced. Both of them tended to confuse the same combinations of shapes frequently. These results suggest that monkeys and humans perceive shapes defined by motion cues in a similar manner and probably have common neural mechanisms to perceive them. Electronic Publication     

板皮形状与尺寸的数学描述理论

本文为制材、剩余物利用等行业需要的板皮数控加工提供数学描述理论,提出的这些理论将为板皮裁边的数控加工数学模型建立提供编程的数学方程,为板材最优下锯的视频再现提供数学方法.本文提出的理论还将为锯切、板皮材积精确检测提供理论依据,与制材工艺结合起来,将使传统加工工艺数学化,为科学管理和数字化控制提供了理论.本文是木材工业中用板皮数学描述加工过程的开始.通过本文的研究,可以推进木材工业加工过程数学描述研究的开展.     

New Docking Algorithm Based on Fuzzy Set Theory

A new docking algorithm based on shape complementarity is presented. The algorithm is based on Fuzzy Logic strategies. A small number of possible docking configurations is selected using partial ordering of a fuzzy measure of topographical properties between complementary surface patches. The algorithm was tested with the structures of three protein-protein-complexes of serin proteases. In one case the components determined separately by x-ray investigations whereas in the other cases the components obtained from the known complex structure were used.Electronic Supplementary Material available.     

On the gestalt concept

We define a gestalt as the invariants of a collection of patterns that can mutually be transformed into each other through a class of transformations encoded by, or conversely, determining that gestalt. The class of these transformations needs to satisfy structural regularities like the ones of the mathematical structure of a group. This makes an analysis of a gestalt possible in terms of relations between its representing patterns. While the gestalt concept has its origins in cognitive psychology, it has also important implications for morphology.     

The spherical deformation model

Miller et al. (1994) describe a model for representing spatial objects with no obvious landmarks. Each object is represented by a global translation and a normal deformation of a sphere. The normal deformation is defined via the orthonormal spherical-harmonic basis. In this paper we analyse the spherical deformation model in detail and describe how it may be used to summarize the shape of star-shaped three-dimensional objects with few parameters. It is of interest to make statistical inference about the three-dimensional shape parameters from continuous observations of the surface and from a single central section of the object. We use maximum-likelihood-based inference for this purpose and demonstrate the suggested methods on real data.