Aurora-A Breaks Symmetry in Contractile Actomyosin Networks Independently of Its Role in Centrosome Maturation

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A Review of Ship Breaking and Rig Scrapping in the Gulf of Mexico

Ship breaking and rig scrapping is the process in which a unit is broken down and recycled into salvageable components, cut into pieces, and transported to a domestic steel mill or exported on a cargo vessel. Breaking is a labor-intensive, low-technology, and relatively homogeneous industry. Work conditions in breaking yards are difficult, dangerous, and potentially hazardous, with operations that are not well suited for mechanization. Ship breaking and rig scrapping share many common features in workflows, worker safety, and environmental issues, but also have notable differences in breaking cost and industry structure. Ship breaking and rig scrapping do not play a major role in the material handled by scrap processors in the United States, but they are part of the unique industrial landscape associated with the offshore energy industry. The purpose of this article is to review the scrap and storage markets for ships and rigs in the Gulf of Mexico. The disposal alternatives, inventory statistics, and the factors that influence breaking and disposal cost are reviewed. The primary environmental protection and worker safety statutes are also outlined.     

Identification of new sources of resistance to resistance-breaking isolates of tomato spotted wilt virus

The tomato as both a fresh consumption and industrial product is one of the most profitable vegetables and has a large cultivation area in the world. Parallel to intense production activities, Tomato Spotted Wilt Virus (TSWV), like viral diseases, results in significant economic losses every year. Use of resistant cultivars is the most efficient and environmental-friendly method of fighting against these diseases. This study was conducted to develop new tomato genetic resources resistant to TSWV because of the Sw-5 resistance breaking (RB) isolates that were determined in tomato cultivation areas. In this study, a total of 40 tomato materials including 15 lines, 9 commercial varieties and 16 wild genotypes were by tested with molecular and biological testing methods. Mechanical inoculation method was used for biological testing and SCAR marker was used in molecular analysis. S. penellii, S. chmielewski, S. habrochaites, S. peruvianum and S. sitiens, LA0716, LA1028, LA1777, LA2744 and LA4110 genotypes were found as resistant against breaking isolates of Tomato Spotted Wilt Virus. These genotypes may be a good resistance source for the future breeding studies in tomato.     

Evolution by hybridisation. The influence of reticulate evolution on biosymmetrical patterns and processes in plants

Natural hybridisation in plants is one of the most striking modes of evolution, when looking at the effects reticulation may have on patterns and processes of the evolutionary history of the affected system. Among other functional constraints, symmetry is regarded as a major factor of or for evolution. A loss of symmetry, that means origin of asymmetrical phenomena can in some cases be linked to environmental or genetic stresses, such as hybridisation. It has been shown that the discussion on reticulation and symmetrical evolution is strongly influenced by a zoocentric evolutionary view, but more focus is needed on the differences between the organisms subject to the study. Plant hybridogenic evolution with the subsequent possibility of polyploidisation and the consequent reduced homology is a completely different phenomenon compared to animal evolution. This article examines the role of symmetry for plant evolution by concentration on two topics: (a) spatial asymmetry on multiple levels caused by hybridisation, and (b) temporal asymmetry (changes of rhythms inherent to specific systems) as an effect of reticulation.     

Ludwik Fleck and the causative agent of syphilis: sociology or pathology of science? A rejoinder to Jean Lindenmann

In 1905 two different microbes were proposed to fill the vacant role of etiologic agent for syphilis, one, the Cytorrhyctes luis, by John Siegel, the other, Spirochaeta pallida, by Fritz Schaudinn. After gathering and reviewing the evidence the majority of medical scientists decided in favor of Schaudinn’s candidate. In a previous issue Jean Lindenmann challenged Ludwik Fleck’s suggestion that under suitable social conditions Siegel’s candidate could just as well have won acceptance by the scientific community (Lindenmann, 2001). To refute this counterfactual thesis, Lindenmann presented an asymmetric account of the dispute over the etiology of syphilis. He adopted the view of the proponents that Schaudinn’s spirochete had already been there in syphilitic lesions for centuries, only awaiting the discovery of an appropriate staining technique to be revealed. Here a more symmetric analysis of the episode will be attempted, paying serious attention to the arguments put forward by the spirochete’s opponents, who expatiated on the many possibilities of inadvertently creating artifacts through microscopic preparation and staining. The symmetric account that is presented in this rejoinder thus aims to trace the simultaneous construction of facts and artifacts. It will not, however, resurrect Fleck’s counterfactual thesis.     

Z曲线的理论研究

DNA序列与正四面体(RT)中的映象点(D格点)具有对应关系．一系列D格点形成晶格(D晶格)．D晶格证明是面心立方晶格,并揭示了D格点的空间分布规律．在此基础上得到Z曲线的一些特性,如Z曲线束具有S4群的对称性。Z曲线均在最大正四面体的内切球内等等．     

Proposing a new index to quantify instantaneous symmetry during manual wheelchair propulsion

Propelling a manual wheelchair (MWC) is a strenuous task that causes upper limb musculoskeletal disorders (MSD) in a large proportion of MWC users. Although most studies on MWC propulsion biomechanics assume that MWC propulsion is a relatively symmetric task, recent literature suggests that this is the case only when the assessed outcome measures are averaged over long periods of time, and not over short periods (i.e., instantaneously). No method is currently available to assess instantaneous symmetry. In this work, we present the Instantaneous Symmetry Index (ISI), a new method that quantifies how a variable has been instantaneously asymmetric during a selected time period. Thirteen experienced MWC users propelled on different cross slopes of 0%, 2%, 4%, 6% and 8%. As the cross slope is increased, the upper hand produced less propulsive moments and the lower hand produced more propulsive movements. This has been reflected in the ISI, which increased from 0.20 (0% slope) to 0.84 (8% slope) with a Spearman׳s coefficient of 0.90. The ISI has great potential to evaluate the ability of a user to propel symmetrically and synchronously, and will be a relevant measure to include in future studies on the impact of MWC propulsion asymmetry on MSD risk.     

线粒体遗传密码及基因组遗传密码的对称分析

病毒、细菌和真核生物的氨基酸编码都使用相同的遗传密码,表明它们可能有共同的来源。但人和牛的线粒体的遗传密码和基因组的遗传密码相比,出现以下不同;（1）ATA编码甲硫氮酸M而不是异亮氨酸I。（2）TGA不再是终止密码子X而编码色氨酸W。（3）AGA和AGG不再是精氨酸R的密码子而变为终止密码子X。应用高维空间拓扑分析的方法,对线粒体遗传密码和基因组遗传密码的6维编码空间进行对称性分析,得到如下结果：（1）线粒体遗传密码的起始密码子是2个而不是1个。（2）线粒体遗传密码的终止密码子是4个而不是3个。（3）线粒体遗传密码空间只有2、4、6三种偶数简并度而没1、3两种奇数简并度,表明其对称度较高。（4）线粒体遗传密码空间除丝氨酸S分成两个平行的子空间之外,终止密码子X亦分成两个平行的子空间,表明其连通度较低。（5）线粒体遗传密码一基因组遗传密码相比,共有3个简并平面出现变异,即：1001λλ（M和I）,011λ1λ（W和X）,以及1011λλ（S和X或S和R）。（6）基因组遗传密码的1、3两种奇数简并度可能来源于线粒体遗传密码的1001λλ平面和011λ1λ平面的对称性破缺。对线粒体遗传密码变异的生物学意义及遗传密码的起源进行了分析和讨论。