Rostroconchia: a new class of bivalved mollusks

Four Paleozoic bivalved genera are assigned to the new molluscan class Rostroconchia: Eopteria, Euchasma, Conocardium, and Pseudoconocardium. These mollusks have ani uncoiled univalved larval shell; an untorted bivalved adult shell; no hinge teeth, ligament, or adductor muscles; and a fused, almost inflexible. hinge. Rostroconchianis developed separately from the pelecypods through the ribeirioids, but are regarded as more closely related to the Pelecypoda and Scaphopoda than to other known classes of mollusks.     

Energetics of honeybee swarm thermoregulation

Honeybee swarms regulate their core temperature at a high set point (near 36 degrees C) and the mantle at a low set point (near 15 degrees C). The temperature gradient from core to mantle permits considerable energy economy, and it is abolished only shortly before swarm takeoff.     

Origins of agriculture at Kuk Swamp in the highlands of New Guinea

Multidisciplinary investigations at Kuk Swamp in the Highlands of Papua New Guinea show that agriculture arose independently in New Guinea by at least 6950 to 6440 calibrated years before the present (cal yr B.P.). Plant exploitation and some cultivation occurred on the wetland margin at 10,220 to 9910 cal yr B.P. (phase 1), mounding cultivation began by 6950 to 6440 cal yr B.P. (phase 2), and ditched cultivation began by 4350 to 3980 cal yr B.P. (phase 3). Clearance of lower montane rainforests began in the early Holocene, with modification to grassland at 6950 to 6440 cal yr B.P. Taro (Colocasia esculenta) was utilized in the early Holocene, and bananas (Musa spp.) were intensively cultivated by at least 6950 to 6440 cal yr B.P.     

Multi-university research teams: shifting impact, geography, and stratification in science

This paper demonstrates that teamwork in science increasingly spans university boundaries, a dramatic shift in knowledge production that generalizes across virtually all fields of science, engineering, and social science. Moreover, elite universities play a dominant role in this shift. By examining 4.2 million papers published over three decades, we found that multi-university collaborations (i) are the fastest growing type of authorship structure, (ii) produce the highest-impact papers when they include a top-tier university, and (iii) are increasingly stratified by in-group university rank. Despite the rising frequency of research that crosses university boundaries, the intensification of social stratification in multi-university collaborations suggests a concentration of the production of scientific knowledge in fewer rather than more centers of high-impact science.     

欧洲精细农业的发展

精细农业是基于农田空间与时间信息的变量农作管理来增加经济收入和减少环境影响。在一系列管理体系内,通过采用适当的技术可实现这个目的。工程技术提供了工具及其使用的管理决策。精细农业应用这些新技术来减少对单位面积农田的经营成本,从农场到农田,甚至田间。农场管理相对