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Overview of organohalide-respiring bacteria and a proposal for a classification system for reductive dehalogenases
Organohalide respiration is an anaerobic bacterial respiratory process that uses halogenated hydrocarbons as terminal electron acceptors during electron transport-based energy conservation. This dechlorination process has triggered considerable interest for detoxification of anthropogenic groundwater contaminants. Organohalide-respiring bacteria have been identified from multiple bacterial phyla, and can be categorized as obligate and non-obligate organohalide respirers. The majority of the currently known organohalide-respiring bacteria carry multiple reductive dehalogenase genes. Analysis of a curated set of reductive dehalogenases reveals that sequence similarity and substrate specificity are generally not correlated, making functional prediction from sequence information difficult. In this article, an orthologue-based classification system for the reductive dehalogenases is proposed to aid integration of new sequencing data and to unify terminology.
Journal Article
Gamification of Cognitive Assessment and Cognitive Training: A Systematic Review of Applications and Efficacy
Cognitive tasks are typically viewed as effortful, frustrating, and repetitive, which often leads to participant disengagement. This, in turn, may negatively impact data quality and/or reduce intervention effects. However, gamification may provide a possible solution. If game design features can be incorporated into cognitive tasks without undermining their scientific value, then data quality, intervention effects, and participant engagement may be improved.
This systematic review aims to explore and evaluate the ways in which gamification has already been used for cognitive training and assessment purposes. We hope to answer 3 questions: (1) Why have researchers opted to use gamification? (2) What domains has gamification been applied in? (3) How successful has gamification been in cognitive research thus far?
We systematically searched several Web-based databases, searching the titles, abstracts, and keywords of database entries using the search strategy (gamif* OR game OR games) AND (cognit* OR engag* OR behavi* OR health* OR attention OR motiv*). Searches included papers published in English between January 2007 and October 2015.
Our review identified 33 relevant studies, covering 31 gamified cognitive tasks used across a range of disorders and cognitive domains. We identified 7 reasons for researchers opting to gamify their cognitive training and testing. We found that working memory and general executive functions were common targets for both gamified assessment and training. Gamified tests were typically validated successfully, although mixed-domain measurement was a problem. Gamified training appears to be highly engaging and does boost participant motivation, but mixed effects of gamification on task performance were reported.
Heterogeneous study designs and typically small sample sizes highlight the need for further research in both gamified training and testing. Nevertheless, careful application of gamification can provide a way to develop engaging and yet scientifically valid cognitive assessments, and it is likely worthwhile to continue to develop gamified cognitive tasks in the future.
Journal Article
Vladimir Lenin and the Russian Revolution
\"Describes the life of Vladimir Lenin and his philosophies which led to the Russian revolution in the 20th century\"-- Provided by publisher.
Book
Evidence for extensive anaerobic dechlorination and transformation of the pesticide chlordecone (C10Cl10O) by indigenous microbes in microcosms from Guadeloupe soil
The historic use of chlordecone (C10Cl10O) as a pesticide to control banana weevil infestations has resulted in pollution of large land areas in the French West Indies. Although currently banned, chlordecone persists because it adsorbs strongly to soil and its complex bis-homocubane structure is stable, particularly under aerobic conditions. Abiotic chemical transformation catalyzed by reduced vitamin B12 has been shown to break down chlordecone by opening the cage structure to produce C9 polychloroindenes. More recently these C9 polychloroindenes were also observed as products of anaerobic microbiological transformation. To investigate the anaerobic biotransformation of chlordecone by microbes native to the French West Indies, microcosms were constructed anaerobically from chlordecone impacted Guadeloupe soil and sludge to mimic natural attenuation and eletron donor-stimulated reductive dechlorination. Original microcosms and transfers were incubated over a period of 8 years, during which they were repeatedly amended with chlordecone and electron donor (ethanol and acetone). Using LC-MS, chlordecone and degradation products were detected in all the biologically active microcosms. Observed products included monohydro-, dihydro- and trihydrochlordecone derivatives (C10Cl10-nO2Hn; n = 1,2,3), as well as \"open cage\" C9 polychloroindene compounds (C9Cl5-nH3+n n = 0,1,2) and C10 carboxylated polychloroindene derivatives (C10Cl4-nO2H4+n, n = 0-3). Products with as many as 9 chlorine atoms removed were detected. These products were not observed in sterile (poisoned) microcosms. Chlordecone concentrations decreased in active microcosms as concentrations of products increased, indicating that anaerobic dechlorination processes have occurred. The data enabled a crude estimation of partitioning coefficients between soil and water, showing that carboxylated intermediates sorb poorly and as a consequence may be flushed away, while polychlorinated indenes sorb strongly to soil. Microbial community analysis in microcosms revealed enrichment of anaerobic fermenting and acetogenic microbes possibly involved in anaerobic chlordecone biotransformation. It thus should be possible to stimuilate anaerobic dechlorination through donor amendment to contaminated soils, particularly as some metabolites (in particular pentachloroindene) were already detected in field samples as a result of intrinsic processes. Extensive dechlorination in the microcosms, with evidence for up to 9 Cl atoms removed from the parent molecule is game-changing, giving hope to the possibility of using bioremediation to reduce the impact of CLD contamination.
Journal Article
Uncertain images : museums and the work of photographs
\"Almost all museums hold photographs in their collections, and museum professionals and their audiences engage with photographs in a myriad of ways. Yet despite some three decades of critical museology and photographic theory, and an extensive debate on the politics of representation, outside art museums, almost no critical attention has been given specifically to the roles, purposes and lives of these photographs within museums\"--Provided by publisher.
Book
Photographs Objects Histories
This innovative volume explores the idea that while photographs are images, they are also objects, and this materiality is integral to their meaning and use. The case studies presented focus on photographs active in different institutional, political, religious and domestic spheres, where physical properties, the nature of their use and the cultural formations in which they function make their 'objectness' central to how we should understand them. The book's contributions are drawn from disciplines including the history of photography, visual anthropology and art history, with case studies from a range of countries such as the Netherlands, North America, Australia, Japan, Romania and Tibet. Each shows the methodological strategies they have developed in order to fully exploit the idea of the materiality of photographic images.
eBook
Investigation of active site amino acid influence on carbon and chlorine isotope fractionation during reductive dechlorination
Abstract
Reductive dehalogenases (RDases) are corrinoid-dependent enzymes that reductively dehalogenate organohalides in respiratory processes. By comparing isotope effects in biotically catalyzed reactions to reference experiments with abiotic corrinoid catalysts, compound-specific isotope analysis (CSIA) has been shown to yield valuable insights into enzyme mechanisms and kinetics, including RDases. Here, we report isotopic fractionation (ε) during biotransformation of chloroform (CF) for carbon (εC = -1.52 ± 0.34‰) and chlorine (εCl = -1.84 ± 0.19‰), corresponding to a ΛC/Cl value of 1.13 ± 0.35. These results are highly suppressed compared to isotope effects observed both during CF biotransformation by another organism with a highly similar RDase (>95% sequence identity) at the amino acid level, and to those observed during abiotic dehalogenation of CF. Amino acid differences occur at four locations within the two different RDases’ active sites, and this study examines whether these differences potentially affect the observed εC, εCl, and ΛC/Cl. Structural protein models approximating the locations of the residues elucidate possible controls on reaction mechanisms and/or substrate binding efficiency. These four locations are not conserved among other chloroalkane reducing RDases with high amino acid similarity (>90%), suggesting that these locations may be important in determining isotope fractionation within this homologous group of RDases.
This study investigates the relationship between active site amino acid sequences with carbon and chlorine isotope fractionation for chlorinated alkane biotransformation by reductive dehalogenases..
Journal Article