Across-shore distribution of Ocypode quadrata burrows in relation to beach features and human disturbance

Spatial distribution patterns of the ghost crab Ocypode quadrata were analysed using different approaches at one disturbed and two preserved reflective sandy beaches of the Mexican Caribbean. We used spatial correlation analysis to describe the across-shore distribution of O. quadrata and their patch dynamics by beach and sampling time. In addition, we analysed the across-shore variability of habitat extent of O. quadrata (habitat envelope) and its relation to human disturbance and beach features. The spatial structure of burrow density was consistent through time, showing a bimodal distribution with very low abundance in the mid distribution range and a discrete increment of burrows to landward. Nonetheless, the size of patches varied temporally for the three beaches. Burrow size increased from seaward to landward. The location of the first burrow and the habitat envelope varied among sampling times and beaches. The location of the first burrow is mostly mediated by the swash climate, while the habitat envelope is mainly controlled by the level of human disturbance. Despite the low number of disturbed and control beaches, our results suggest that the habitat envelope could be included in future studies when using ghost crabs as indicators of human disturbance. Polynomial models and variographic analysis proved to be useful tools to describe the across-shore distribution and patch dynamics of the ghost crab.     

Explanation,understanding, and unrealistic models

How can false models be explanatory? And how can they help us to understand the way the world works? Sometimes scientists have little hope of building models that approximate the world they observe. Even in such cases, I argue, the models they build can have explanatory import. The basic idea is that scientists provide causal explanations of why the regularity entailed by an abstract and idealized model fails to obtain. They do so by relaxing some of its unrealistic assumptions. This method of ‘explanation by relaxation’ captures the explanatory import of some important models in economics. I contrast this method with the accounts that Daniel Hausman and Nancy Cartwright have provided of explanation in economics. Their accounts are unsatisfactory because they require that the economic model regularities obtain, which is rarely the case. I go on to argue that counterfactual regularities play a central role in achieving ‘understanding by relaxation.’ This has a surprising implication for the relation between explanation and understanding: Achieving scientific understanding does not require the ability to explain observed regularities.     

Zur Histologie der Lungenveränderungen bei der Valléeschen Krankheit

Summary 31 lungs of cases of infectious anemia and 7 lungs showing other diseases of horses, all with a good clinical history based on personal observation, were studied.All subacute and chronic cases of infectious anemia showed distinct swelling and proliferation of endothelial cells both in the capillaries and small blood vessels. These changes were absent in other diseases as well as in old latent and very recent acute cases of infectious anemia.     

一种连续产生次氯酸钠的管状电化学反应杀菌器

介绍了一种中试规模的用于原位清洗（CIP）或原位灭菌（SIP）的次氯酸钠连续发生器,其电解槽采用带尼龙隔膜的管式电化学反应器结构,并在钛阳极管的表面采用稀土金属氧化物二氧化钌（RuO2）作为电化学反应的活性催化涂层,文中从反应工程的角度分析了该发生器的性能,试验结果表明,该反应器的电流效率在82％以上,微生物学研究表明,有效氯含量范围内的消毒水可有效杀灭大部分食品工业设备表面所发现的微生物。     

蛋白石薄膜及其异质结构的可控制备

利用毛细管辅助沉积方法制备了厚度及膜内裂缝的形状、分布可控的三维蛋白石薄膜。讨论了所得薄膜光学性质以及膜的形态特性与薄膜厚度之间的关系。用同样的方法制备了由不同粒径的球体基元晶体带构成的横向交替异质结构。