Optimal variable weighting for hierarchical clustering: An alternating least-squares algorithm

This paper presents the development of a new methodology which simultaneously estimates in a least-squares fashion both an ultrametric tree and respective variable weightings for profile data that have been converted into (weighted) Euclidean distances. We first review the relevant classification literature on this topic. The new methodology is presented including the alternating least-squares algorithm used to estimate the parameters. The method is applied to a synthetic data set with known structure as a test of its operation. An application of this new methodology to ethnic group rating data is also discussed. Finally, extensions of the procedure to model additive, multiple, and three-way trees are mentioned.The first author is supported as Bevoegdverklaard Navorser of the Belgian Nationaal Fonds voor Wetenschappelijk Onderzoek.     

Amino acid concentrations in blood of patients with an acute myocardial infarction

Summary Levels of essential and nonessential amino acids in blood of patients with an acute myocardial infarction (AMI) were found in general not to differ from values obtained from non-AMI patients. This is in contrast to blood taurine levels which are elevated in the AMI patients.     

Defining the role of post-synaptic α-neurotoxins in paralysis due to snake envenoming in humans

Snake venom α-neurotoxins potently inhibit rodent nicotinic acetylcholine receptors (nAChRs), but their activity on human receptors and their role in human paralysis from snakebite remain unclear. We demonstrate that two short-chain α-neurotoxins (SαNTx) functionally inhibit human muscle-type nAChR, but are markedly more reversible than against rat receptors. In contrast, two long-chain α-neurotoxins (LαNTx) show no species differences in potency or reversibility. Mutant studies identified two key residues accounting for this. Proteomic and clinical data suggest that paralysis in human snakebites is not associated with SαNTx, but with LαNTx, such as in cobras. Neuromuscular blockade produced by both subclasses of α-neurotoxins was reversed by antivenom in rat nerve–muscle preparations, supporting its effectiveness in human post-synaptic paralysis.     

数字信号处理（DSP）算法的合成和优化

本书详细介绍了数字信号处理器的硬件合成和硬件定制实现的优化方法领域的研究动态，高层次的讨论了在满足用户给定的限制条件下，如何自动化进行高性能一面积比（area—efficient）设计的技术，指出了这类技术可以用于线性系统和非线性系统：包括有限长脉冲（FIR）和无限长脉冲（IIR）滤波器、离散余弦变换（DCT）、多相滤波器组和自适应最小均方（LMS）滤波器。     

Distribution of vertebrates of the Bighorn Canyon National Recreation Area

During a survey of the vertebrates in the Bighorn Canyon National Recreation Area, 46 mammal, 210 bird, 9 reptile, 5 amphibian, and 28 fish species were found. Habitat structure and moisture were two environmental variables associated with species numbers across this 1,820-ha area. Eight distinct habitats were evaluated. In coniferous forests, 27% of the birds and 54% of the mammals were observed. Sagebrush/grasslands and upland shrublands were very arid and had relatively few vertebrates. Five introduced game birds occurred in sagebrush habitat. Riparian and wetland habitats had the largest number of unique vertebrates, 38 and 77 respectively. The establishment of Bighorn Lake in 1968 influenced the fisheries in streams and rivers as 10 introduced fish species are now there.     

Longitudinal development of macroinvertebrate communities below oligotrophic lake outlets

Benthic macroinvertebrates were collected at several sites downstream of three oligotrophic lake outfalls in July 1986. Total numbers, biomass, and species richness increased rapidly immediately downstream from the outlets and then either stabilized or continued to increase downstream in parallel with benthic organic matter standing crops. Filter feeder densities showed an initial buildup and then decline downstream from the outlets. Variability in longitudinal patterns of other functional feeding groups among lake outlets was related to differences in food quantity and quality, and microhabitat. An additional set of samples was collected at Pettit Lake outlet in August 1986. Species richness and total density peaked sooner under baseflow conditions in August than under spring runoff conditions in June. Distributions of all functional feeding groups, except filter feeders, also differed between the two periods, reflecting differences in the physical environment. We conclude that reduced lentic inputs of particulate organic matter seston and improved habitat suitability downstream are responsible for the progressive development of macroinvertebrate communities in oligotrophic lake outlets. These data imply the importance of the habitat templet in the structuring of benthic communities.     

Growth and reproduction in an alpine cushion plant: Astragalus kentrophyta var. implexus

A two-year field experiment was conducted to investigate factors hypothesized to affect the reproductive potential of Astragalus kentrophyta var. implexus and to test the importance of trade-offs between growth and reproduction in this species. Levels of mineral nutrients, water, herbivory, and competition were manipulated. Seed output and growth of individuals in treatment groups were compared against control plants. Neither water nor mineral nutrients alone were shown to affect growth or reproduction. Herbivory was shown to be similarly unimportant in affecting growth and reproduction. Competition with other species influenced growth but not reproduction. No significant trade-offs between growth and reproduction were detected within years. However, there did appear to be a trade-off between these major fitness components when compared between years.     

Sources of variation in counts of meristic features of Yellowstone cutthroat trout ( Oncorhynchus clarki bouvieri )

We determined variability in counts of meristic features (pyloric caecae, vertebrae, pelvic fin rays, gillrakers, basibranchial teeth, scales above the lateral line, and scales in the lateral series) of Yellowstone cutthroat trout ( Oncorhynchus clarki bouvieri ) by 3 independent readers, by the same reader on 3 different occasions, and among fish from 12 sampling sites within a 650-km 2 watershed. Genetic purity of the cutthroat trout was determined by electrophoretic analysis. Significant differences in meristic counts were observed among 3 readers and among sampling sites, but not among 3 occasions by a single reader. Scale counts were within the reported range for Yellowstone cutthroat trout, but counts of other structures (pyloric caecae, gillrakers, vertebrae) were as similar to rainbow trout as to Yellowstone cutthroat trout. Meristic counts identified the fish as cutthroat trout; however, variation among readers and sampling sites, as well as within the species, limits their use when identifying genetically pure cutthroat trout or assessing possible integration with rainbow trout.     

Discovery of a sensory organ that coordinates lunge feeding in rorqual whales

Top ocean predators have evolved multiple solutions to the challenges of feeding in the water. At the largest scale, rorqual whales (Balaenopteridae) engulf and filter prey-laden water by lunge feeding, a strategy that is unique among vertebrates. Lunge feeding is facilitated by several morphological specializations, including bilaterally separate jaws that loosely articulate with the skull, hyper-expandable throat pleats, or ventral groove blubber, and a rigid y-shaped fibrocartilage structure branching from the chin into the ventral groove blubber. The linkages and functional coordination among these features, however, remain poorly understood. Here we report the discovery of a sensory organ embedded within the fibrous symphysis between the unfused jaws that is present in several rorqual species, at both fetal and adult stages. Vascular and nervous tissue derived from the ancestral, anterior-most tooth socket insert into this organ, which contains connective tissue and papillae suspended in a gel-like matrix. These papillae show the hallmarks of a mechanoreceptor, containing nerves and encapsulated nerve termini. Histological, anatomical and kinematic evidence indicate that this sensory organ responds to both the dynamic rotation of the jaws during mouth opening and closure, and ventral groove blubber expansion through direct mechanical linkage with the y-shaped fibrocartilage structure. Along with vibrissae on the chin, providing tactile prey sensation, this organ provides the necessary input to the brain for coordinating the initiation, modulation and end stages of engulfment, a paradigm that is consistent with unsteady hydrodynamic models and tag data from lunge-feeding rorquals. Despite the antiquity of unfused jaws in baleen whales since the late Oligocene (～23-28 million years ago), this organ represents an evolutionary novelty for rorquals, based on its absence in all other lineages of extant baleen whales. This innovation has a fundamental role in one of the most extreme feeding methods in aquatic vertebrates, which facilitated the evolution of the largest vertebrates ever.