Dental microwear texture analysis shows within-species diet variability in fossil hominins

Reconstructing the diets of extinct hominins is essential to understanding the paleobiology and evolutionary history of our lineage. Dental microwear, the study of microscopic tooth-wear resulting from use, provides direct evidence of what an individual ate in the past. Unfortunately, established methods of studying microwear are plagued with low repeatability and high observer error. Here we apply an objective, repeatable approach for studying three-dimensional microwear surface texture to extinct South African hominins. Scanning confocal microscopy together with scale-sensitive fractal analysis are used to characterize the complexity and anisotropy of microwear. Results for living primates show that this approach can distinguish among diets characterized by different fracture properties. When applied to hominins, microwear texture analysis indicates that Australopithecus africanus microwear is more anisotropic, but also more variable in anisotropy than Paranthropus robustus. This latter species has more complex microwear textures, but is also more variable in complexity than A. africanus. This suggests that A. africanus ate more tough foods and P. robustus consumed more hard and brittle items, but that both had variable and overlapping diets.     

试论我国政府经济职能的科学定位

介绍了政府经济职能的内涵、发达市场经济国家政府经济职能的定位和我国政府经济职能的科学定位，提出了我国经济发展面临的新问题。     

Early hominid diets from quantitative image analysis of dental microwear

The dietary habits of the early hominids Australopithecus and Paranthropus have long been debated. Robinson argued that the two species differed in the proportions of meat and vegetables consumed. More recently it has been suggested that Paranthropus, with its presumably larger body size, simply processed greater amounts of the same foods eaten by Australopithecus to maintain 'functional equivalence'. Microscopic dental wear patterns are related to the dietary habits of extant mammals, and quantification of these patterns is useful in distinguishing among primates with different diets. Nevertheless, few attempts have been made to use microwear in the reconstruction of early hominid diets, and only very recently has the quantification of such data been initiated. While microwear fabrics can be reduced to individual elements (for example, scratches and pits), there is some disagreement over exactly how they should be defined and measured. Fourier transforms have been applied successfully in the study of a variety of physical and biological patterns, and recently they have been used to characterize and distinguish different tooth wear patterns more objectively. Here we report the first combined use of image processing and other quantitative techniques to analyse the dental microwear of early hominids. Our results suggest that Paranthropus ate substantially more hard food items than Australopithecus.     

网络环境下的用户信息需求与高校图书馆信息服务

随着计算机技术、通信技术、网络技术的应用，图书馆服务模式发生了巨大变化。在分析传统信息服务模式的基础上，针对高校图书馆用户的信息需求，提出了网络环境下信息服务的新思路。     

水轮机组发电机空气间隙的控制分析

对影响水轮机组空气间隙的因素及其精度进行了分析，提出合理的质量标准，探讨了厂房倾斜等因素对空气间隙的影响及其测量调整方法，以确保空气间隙均匀合格。