The phylogenetic position of the 'giant deer' Megaloceros giganteus

The giant deer, or 'Irish elk', has featured extensively in debates on adaptation, sexual selection, and extinction. Its huge antlers--the largest of any deer species, living or extinct--formed a focus of much past work. Yet the phylogenetic position of the giant deer has remained an enigma. On the basis of its flattened antlers, the species was previously regarded as closely related to the living fallow deer. Recent morphological studies, however, have challenged that view and placed the giant deer closer to the living red deer or wapiti. Here we present a new phylogenetic analysis encompassing morphological and DNA sequence evidence, and find that both sets of data independently support a sister-group relationship of giant and fallow deer. Our results include the successful extraction and sequencing of DNA from this extinct species, and highlight the value of a joint molecular and morphological approach.     

Novel estrogen receptor coregulators and signaling molecules in human diseases

The steroid hormone estrogen and signaling from its receptors are increasingly recognized as critical mediators of a variety of organ-specific biological processes. Recent advances in the identification and functional characterization of novel estrogen receptor interacting proteins clearly show the complexity of hormonal signaling regulation, but may also contribute to our understanding of the roles of estrogen signaling in normal physiology and the pathobiology of human disease.Received 12 June 2003; received after revision 21 July 2003; accepted 29 July 2003     

Addition of nanoparticle dispersions to enhance flux pinning of the YBa2Cu3O7-x superconductor

Following the discovery of type-II high-temperature superconductors in 1986 (refs 1, 2), work has proceeded to develop these materials for power applications. One of the problems, however, has been that magnetic flux is not completely expelled, but rather is contained within magnetic fluxons, whose motion prevents larger supercurrents. It is known that the critical current of these materials can be enhanced by incorporating a high density of extended defects to act as pinning centres for the fluxons. YBa2Cu3O7 (YBCO or 123) is the most promising material for such applications at higher temperatures (liquid nitrogen). Pinning is optimized when the size of the defects approaches the superconducting coherence length ( approximately 2-4 nm for YBCO at temperatures < or =77 K) and when the areal number density of defects is of the order of (H/2) x 10(11) cm(-2), where H is the applied magnetic field in tesla. Such a high density has been difficult to achieve by material-processing methods that maintain a nanosize defect, except through irradiation. Here we report a method for achieving a dispersion of approximately 8-nm-sized nanoparticles in YBCO with a high number density, which increases the critical current (at 77 K) by a factor of two to three for high magnetic fields.     

材料物理与化学重点学科建设的思考

教学型大学的主要任务是提高教学质量,培养应用型高级专门人才.学科建设是人才培养的关键.重点学科建设应结合学科特点和优势,明确学科研究方向,紧密结合教学,突出应用性教育的特点,发挥重点学科的科学研究、人才培养、为社会服务三大职能.就材料物理与化学学科建设提出了自己的初步思考.     

Theoretical prediction of carcinogenicity: Quasi-quantification by quasi-valence. A reply to V. Veljkovic and D. I. Lalovic

Summary We have shown the recently proposed method for prediction of carcinogenicity by average quasi-valence number to be neither a good predictor of carcinogenicity, nor of non-carcinogenicity.Grants to Edward J. Klekowski Jr from the U.S. National Science Foundation and from the office of Water Resources Research, U.S. Department of the Interior under the Water Resources Research Act of 1964, as amended, supported this research.