Kinship categories across languages reflect general communicative principles

Languages vary in their systems of kinship categories, but the scope of possible variation appears to be constrained. Previous accounts of kin classification have often emphasized constraints that are specific to the domain of kinship and are not derived from general principles. Here, we propose an account that is founded on two domain-general principles: Good systems of categories are simple, and they enable informative communication. We show computationally that kin classification systems in the world's languages achieve a near-optimal trade-off between these two competing principles. We also show that our account explains several specific constraints on kin classification proposed previously. Because the principles of simplicity and informativeness are also relevant to other semantic domains, the trade-off between them may provide a domain-general foundation for variation in category systems across languages.     

A general model for food web structure

A central problem in ecology is determining the processes that shape the complex networks known as food webs formed by species and their feeding relationships. The topology of these networks is a major determinant of ecosystems' dynamics and is ultimately responsible for their responses to human impacts. Several simple models have been proposed for the intricate food webs observed in nature. We show that the three main models proposed so far fail to fully replicate the empirical data, and we develop a likelihood-based approach for the direct comparison of alternative models based on the full structure of the network. Results drive a new model that is able to generate all the empirical data sets and to do so with the highest likelihood.     

The structure and symmetry of crystalline solid solutions: a general revision

Mixed single crystals composed of host and guest organic molecules of similar structures and shapes are shown to comprise sectors with different host-guest distributions and to have symmetries lower than that of the host crystal. These properties are determined by the structure of the guest and the surface structures of the crystal faces through which the guest molecules are occluded. This general concept is illustrated by studies of three mixed crystal systems,(E)-cinnamamide-(E)-2-thienylacrylamide, (E)-cinnamamide-(E)-3-thienylacrylamide, and(S)-asparagine-(S)-aspartic acid, with x-ray and neutron diffraction and solid-state photochemistry.     

Sudbury structure, ontario: some petrographic evidence for origin by meteorite impact

Unusual deformation structures, similar to those observed in rocks from known and suspected meteorite impact craters, are observed in inclusions of basement rock in the Onaping formation at Sudbury, Ontario. These features, which include planar sets in quartz parallel to the (0001) and (10ī3) planes, suggest that the Onaping formation consists of shocked and melted material deposited immediately after a meteorite impact which formed the Sudbury basin.     

Semiconductor Radiation Detectors: Basic principles and some uses of a recent tool that has revolutionized nuclear physics are described

The past decade has seen the rapid development and exploitation of one of the most significant tools of nuclear physics, the semiconductor radiation detector. Applications of the device to the analysis of materials promises to be one of the major contributions of nuclear research to technology, and may even assist in some aspects of our environmental problems. In parallel with the development of these applications, further developments in detectors for nuclear research are taking place: the use of very thin detectors for heavyion identification, position-sensitive detectors for nuclear-reaction studies, and very pure germanium for making more satisfactory detectors for many applications suggest major future contributions to physics.     

Membrane permeability: monolayer relationships

A model of permeation of living membranes is proposed in which penetration by polar molecules takes place through islands composed of limited numbers of lipoidal molecules in a state comparable to that of certain compressed monolayers. These islands are visualized as scattered within a rigid, relatively impervious matrix. Relationships for penetration of monolayers by gases have been applied to this membrane model. Calculations on this basis demonstrate that the permeabilities relative to water are described at least as well by this model as by that assuming rigid pores of 4.25 A radius.     

Myelin Membrane: a molecular abnormality

Myelin was isolated from cerebral white matter from a patient who had died of metachromatic leukodystrophy, and its lipid composition was analyzed. Although the lipid content was nearly normal, the myelin contained a three- to fourfold excess of cerebroside sulfate and a threefold deficiency of cerebroside compared to normal myelin. The deficiency of cerebroside and the excess of cerebroside sulfate may account for defective myelination in this disease.     

Brain evolution: new light on old principles

The fossil evidence on the evolution of brains and bodies in mammals shows that there has been a progressive increase in relative brain size accompanied by and correlated with increased diversity among species in relative brain size. Small-brained species have also evolved, but more large-brained species have appeared in successive epochs.     

对浙江省农业产业结构调整的几点思考

当前,中国农业已进入了一个新的发展阶段,要适应新阶段的新变化,调整优化农业产业结构是确保农业生产持续发展,实现农民增收和启动农村市场的一个重大课题。本文从浙江当前农业发展面临的新形势出发,提出把调整优化农业产业结构的立足点放在发挥资源优势和区位优势上,依靠科技进步,大力发展区域特色农业。