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101.
KEVIN J. CARPENTER LAWRENCE CHOW PATRICK J. KEELING 《The Journal of eukaryotic microbiology》2009,56(4):305-313
ABSTRACT. Trichonympha is one of the most complex and visually striking of the hypermastigote parabasalids—a group of anaerobic flagellates found exclusively in hindguts of lower termites and the wood‐feeding cockroach Cryptocercus—but it is one of only two genera common to both groups of insects. We investigated Trichonympha of Cryptocercus using light and electron microscopy (scanning and transmission), as well as molecular phylogeny, to gain a better understanding of its morphology, diversity, and evolution. Microscopy reveals numerous new features, such as previously undetected bacterial surface symbionts, adhesion of post‐rostral flagella, and a distinctive frilled operculum. We also sequenced small subunit rRNA gene from manually isolated species, and carried out an environmental polymerase chain reaction (PCR) survey of Trichonympha diversity, all of which strongly supports monophyly of Trichonympha from Cryptocercus to the exclusion of those sampled from termites. Bayesian and distance methods support a relationship between Trichonympha species from termites and Cryptocercus, although likelihood analysis allies the latter with Eucomonymphidae. A monophyletic Trichonympha is of great interest because recent evidence supports a sister relationship between Cryptocercus and termites, suggesting Trichonympha predates the Cryptocercus‐termite divergence. The monophyly of symbiotic bacteria of Trichonympha raises the intriguing possibility of three‐way co‐speciation among bacteria, Trichonympha, and insect hosts. 相似文献
102.
LAWRENCE A. KUZNAR 《American anthropologist》2007,109(2):318-329
Terrorism is problematic at multiple levels. Social scientists debate its cause; policymakers debate what to do about it; many debate the meaning and political use of the term; and many live in fear of it. Current explanations of terrorism hinge on competing models of decision making. Anthropologists are increasingly influential in decision theory as issues of rationality, culture, and evolutionary psychology are invoked to explain patterns in human decision making. In this article, I review and critique current explanations of terrorism, I relate these explanations to larger debates in decision theory and anthropology, and I present an example of how current schisms may be transcended. 相似文献
103.
Stimulation of both photosynthesis and respiration in response to warmer and drier conditions in a boreal peatland ecosystem 总被引:1,自引:0,他引:1
Peatland ecosystems have been consistent carbon (C) sinks for millennia, but it has been predicted that exposure to warmer temperatures and drier conditions associated with climate change will shift the balance between ecosystem photosynthesis and respiration providing a positive feedback to atmospheric CO2 concentration. Our main objective was to determine the sensitivity of ecosystem photosynthesis, respiration and net ecosystem production (NEP) measured by eddy covariance, to variation in temperature and water table depth associated with interannual shifts in weather during 2004–2009. Our study was conducted in a moderately rich treed fen, the most abundant peatland type in western Canada, in a region (northern Alberta) where peatland ecosystems are a significant landscape component. During the study, the average growing season (May–October) water depth declined approximately 38 cm, and temperature [expressed as cumulative growing degree days (GDD, March–October)] varied approximately 370 GDD. Contrary to previous predictions, both ecosystem photosynthesis and respiration showed similar increases in response to warmer and drier conditions. The ecosystem remained a strong net sink for CO2 with an average NEP (± SD) of 189 ± 47 g C m?2 yr?1. The current net CO2 uptake rates were much higher than C accumulation in peat determined from analyses of the relationship between peat age and cumulative C stock. The balance between C addition to, and total loss from, the top 0–30 cm depth (peat age range 0–70 years) of shallow peat cores averaged 43 ± 12 g C m?2 yr?1. The apparent long‐term average rate of net C accumulation in basal peat samples was 19–24 g C m?2 yr?1. The difference between current rates of net C uptake and historical rates of peat accumulation is likely a result of vegetation succession and recent increases in tree establishment and productivity. 相似文献
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A cytological basis for a map of the nucleolar chromosome in man 总被引:1,自引:0,他引:1
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Some new pilicolous mites from South African mammals 总被引:1,自引:0,他引:1
LAWRENCE RF 《Parasitology》1948,39(1-2):39-42
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LAWRENCE ROSEN 《American anthropologist》1977,79(3):555-578
Anthropologists representing each of the subfields of the discipline have appeared as expert witnesses in a wide range of legal cases. Their appearance raises a number of significant questions about the appropriateness of anthropological knowledge to adversary proceedings, and poses difficult ethical problems for the participant and the profession. The present article reviews a series of cases in which anthropologists have served as expert witnesses and proposes a set of recommended standards and reforms for this activity . [ethics, expert testimony, legal anthropology, American society, applied anthropology] 相似文献