Insurance-based advantage to helpers in a tropical hover wasp

The origin and maintenance of eusociality is a central problem in evolutionary biology. Eusocial groups contain individuals that forfeit their own reproduction in order to help others reproduce. In facultatively eusocial taxa, offspring can choose whether to found new nests or become helpers in their natal groups. In many facultatively eusocial insects, offspring need continuous care during development, but adult carers have life expectancies shorter than the developmental period. When a lone foundress dies, her partly reared brood are usually doomed. Here, we show that helpers in a tropical hover wasp (Liostenogaster flavolineata) have an insurance-based advantage over lone foundresses because after a helper dies, most of the brood that she has partly reared will be brought to maturity by surviving nest-mates. After some of the helpers are experimentally removed from a multi-female nest, the reduced group is left with more brood than it would normally rear. We found that larger, more valuable extra brood were reared through to maturity, but not smaller, less valuable brood. Smaller brood may be sacrificed to feed larger brood, and reduced groups probably benefited from increased short-term helper recruitment. Rearing extra brood did not increase adult mortality or brood development time.     

Functional connectivity in the retina at the resolution of photoreceptors

To understand a neural circuit requires knowledge of its connectivity. Here we report measurements of functional connectivity between the input and ouput layers of the macaque retina at single-cell resolution and the implications of these for colour vision. Multi-electrode technology was used to record simultaneously from complete populations of the retinal ganglion cell types (midget, parasol and small bistratified) that transmit high-resolution visual signals to the brain. Fine-grained visual stimulation was used to identify the location, type and strength of the functional input of each cone photoreceptor to each ganglion cell. The populations of ON and OFF midget and parasol cells each sampled the complete population of long- and middle-wavelength-sensitive cones. However, only OFF midget cells frequently received strong input from short-wavelength-sensitive cones. ON and OFF midget cells showed a small non-random tendency to selectively sample from either long- or middle-wavelength-sensitive cones to a degree not explained by clumping in the cone mosaic. These measurements reveal computations in a neural circuit at the elementary resolution of individual neurons.     

The mental wealth of nations

Countries must learn how to capitalize on their citizens' cognitive resources if they are to prosper, both economically and socially. Early interventions will be key.     

云南保山盆地生物气源岩生物标志化合物特征

通过对保山盆地气源岩有机质饱和烃色谱、三环萜烷、四环萜烷、五环三萜烷及甾烷分布特征的研究,发现气源岩有机质碳数分布存在比较明显的奇碳优势,结合R.数据,认为该区气源岩成熟度很低;可溶有机质生物标志化合物中的三环萜烷、四环萜烷含量低,五环三萜烷中有含量十分丰富的生物藿烷,表明源岩成熟度低;还检测出与细菌作用有关的C<,3...     

Optimization of Permeability Tensor Characteristics of Anisotropic Reservoir and Well Pattern Parameters

The problems of well pattern arrangement, well array direction, and well array spacing ratios for anisotropic reservoirs were studied using tensor analysis. The problems were formulated as a bilevel programming model which was solved using a genetic algorithm. The results show that if the permeability in one direction is much higher than in another direction, the wells should be aligned along the high permeability direction. The analysis provides a theoretical foundation for well pattern arrangement in fractured reservoirs as well as in channel sand reservoirs.     

对少年长跑运动员高原训练期间生理生化指标规律探究

随着竞技体育的发展,每个竞技项目的科技含量越来越高,势必要求业余体育训练也要进行科学训练。采用实验法、文献资料法和逻辑分析法,针对青少年长跑运动员的特点,运用科学监控手段与科学训练方法有机结合,进行深入的实践和研究,达到提高运动成绩的效果。