Meaningful Civicness for the Many: A Comment on Erik Claes

This comment on Erik Claes values his treatment of in-depth interviews to gain a better understanding of how volunteers make sense of their activities, but it questions the representativeness, meaningfulness and civicness of what is found. Meaning as deep personal commitment to an objective value (Susan Wolf) is probably quite exceptional. The values and goals of Claes’s volunteers are deeply human and wide-ranging, but too ignorant of disagreement, power and politics to be called civic.     

An astrolabe attributed to Gerard Mercator,c. 1570

The Istituto e Museo di Storia della Scienza, Florence, Italy, possesses an astrolabe with five latitude plates that is now attributed to the Duisburg workshop of Gerard Mercator. Although it is known that Mercator made instruments, this is the first surviving example to be identified. Another latitude plate is shown to come from the workshop of the Florentine, Giovan Battista Giusti. A seventh plate, possibly engraved by Rumold Mercator, provides the only known Mercatorian polar stereographic projection. The role of Egnazio Danti, cosmographer to the Grand Duke of Tuscany, in the acquisition of the astrolabe in about 1570 is considered.     

Plants lacking the main light-harvesting complex retain photosystem II macro-organization

Photosystem II (PSII) is a key component of photosynthesis, the process of converting sunlight into the chemical energy of life. In plant cells, it forms a unique oligomeric macrostructure in membranes of the chloroplasts. Several light-harvesting antenna complexes are organized precisely in the PSII macrostructure-the major trimeric complexes (LHCII) that bind 70% of PSII chlorophyll and three minor monomeric complexes-which together form PSII supercomplexes. The antenna complexes are essential for collecting sunlight and regulating photosynthesis, but the relationship between these functions and their molecular architecture is unresolved. Here we report that antisense Arabidopsis plants lacking the proteins that form LHCII trimers have PSII supercomplexes with almost identical abundance and structure to those found in wild-type plants. The place of LHCII is taken by a normally minor and monomeric complex, CP26, which is synthesized in large amounts and organized into trimers. Trimerization is clearly not a specific attribute of LHCII. Our results highlight the importance of the PSII macrostructure: in the absence of one of its main components, another protein is recruited to allow it to assemble and function.     

Intracellular gate opening in Shaker K+ channels defined by high-affinity metal bridges

Voltage-gated potassium channels such as Shaker help to control electrical signalling in neurons by regulating the passage of K+ across cell membranes. Ion flow is controlled by a voltage-dependent gate at the intracellular side of the pore, formed by the crossing of four alpha-helices--the inner-pore helices. The prevailing model of gating is based on a comparison of the crystal structures of two bacterial channels--KcsA in a closed state and MthK in an open state--and proposes a hinge motion at a conserved glycine that splays the inner-pore helices wide open. We show here that two types of intersubunit metal bridge, involving cysteines placed near the bundle crossing, can occur simultaneously in the open state. These bridges provide constraints on the open Shaker channel structure, and on the degree of movement upon opening. We conclude that, unlike predictions from the structure of MthK, the inner-pore helices of Shaker probably maintain the KcsA-like bundle-crossing motif in the open state, with a bend in this region at the conserved proline motif (Pro-X-Pro) not found in the bacterial channels. A narrower opening of the bundle crossing in Shaker K+ channels may help to explain why Shaker has an approximately tenfold lower conductance than its bacterial relatives.     

A method for the determination of glutamate oxaloacetate transaminase in sperm plasma from boars and bulls

Summary A method is described for the determination of glutamate oxaloacetate transaminase (GOT) activity in sperm plasma from boars and bulls as a test for fertilizing ability.Publication A-336 of the Research Institute for Animal Husbandry Schoonoord.     

基于社区森林模型的分布式重叠社区发现算法

重叠社区发现是复杂网络挖掘中的重要基础工作,可以应用于社交网络、通讯网络、蛋白质相互作用网络、代谢路径网络、交通网络等多种网络的数据分析,从而服务智慧交通、传染病防治、舆情分析、新药研制和人力资源管理等领域.传统的单机运算架构已经难以满足各类大规模复杂网络的分析和计算要求.人工智能领域的研究人员提出将社区发现应用到网络...     

Transesterification reactions of ethylene glycol cyclic phosphate with 2-aminoalcohols

Résumé Il a été trouvé que l'éthylène glycol phosphate cyclique réagit en solution aqueuse avec plusieurs amino-2 alcools pour donner les phosphodiesters résultants d'une transesterification.     

Early explorations of the southern celestial sky

In this paper the astronomical explorations of the southern celestial sky by Dutch navigators at the end of the sixteenth century are investigated. It is shown that the main motivation for this scientific enterprise stemmed from Dutch cartographic tradition and interests, represented first and foremost by Petrus Plancius and the competing globemakers Hondius and Blaeu. It is shown, too, that at the time actually two surveys were carried out. We have investigated the results of the two surveys by analysing the data presented on celestial globes by Hondius and Blaeu, and in the star catalogue published by De Houtman in 1603. It appears that only after the first survey was it recognized that the stars of the well-known Southern Cross constellation could be matched with stars already recorded by Ptolemy.