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In a universe that is dominated by increasing entropy, living organisms are a curious anomaly. The organization that distinguishes living organisms from their inanimate surroundings relies upon their ability to execute vectorial processes, such as directed movements and the assembly of macromolecules and organelle systems. Many of these phenomena are executed by molecular motors that harness chemical potential energy to perform mechanical work and unidirectional motion. This article explores how these remarkable protein machines might have evolved and what roles they could play in biological and medical research in the coming decades.  相似文献   

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In a universe that is dominated by increasing entropy, living organisms are a curious anomaly. The organization that distinguishes living organisms from their inanimate surroundings relies upon their ability to execute vectorial processes, such as directed movements and the assembly of macromolecules and organelle systems. Many of these phenomena are executed by molecular motors that harness chemical potential energy to perform mechanical work and unidirectional motion. This article explores how these remarkable protein machines might have evolved and what roles they could play in biological and medical research in the coming decades.  相似文献   

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In a universe that is dominated by increasing entropy, living organisms are a curious anomaly. The organization that distinguishes living organisms from their inanimate surroundings relies upon their ability to execute vectorial processes, such as directed movements and the assembly of macromolecules and organelle systems. Many of these phenomena are executed by molecular motors that harness chemical potential energy to perform mechanical work and unidirectional motion. This article explores how these remarkable protein machines might have evolved and what roles they could play in biological and medical research in the coming decades.  相似文献   

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L.H. Johns 《CMAJ》1976,115(3):207-208
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Whereas fossil evidence indicates extensive treeless vegetation and diverse grazing megafauna in Europe and northern Asia during the last glacial, experiments combining vegetation models and climate models have to-date simulated widespread persistence of trees. Resolving this conflict is key to understanding both last glacial ecosystems and extinction of most of the mega-herbivores. Using a dynamic vegetation model (DVM) we explored the implications of the differing climatic conditions generated by a general circulation model (GCM) in “normal” and “hosing” experiments. Whilst the former approximate interstadial conditions, the latter, designed to mimic Heinrich Events, approximate stadial conditions. The “hosing” experiments gave simulated European vegetation much closer in composition to that inferred from fossil evidence than did the “normal” experiments. Given the short duration of interstadials, and the rate at which forest cover expanded during the late-glacial and early Holocene, our results demonstrate the importance of millennial variability in determining the character of last glacial ecosystems.  相似文献   

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The last 5 years have resulted in many advances in knowledge of the cytoskeleton and motility of individual cells. Here the problem of multicellular movement is addressed. The Dictyostelium discoideum slug is examined, and models for how approximately 100,000 cells become coordinated to move are briefly reviewed. Experiments that contributed to model building as well as those used to test models are considered. Four levels of experimentation are considered: (1) the extracellular matrix (ECM) is examined as a component of the system; (2) information obtained by examining the organisation of slug cells through sectioning is presented; (3) time, the 4th dimension, is considered, and approaches to studying the dynamics of cell interactions from the point of view of movement are outlined, and (4) cell adhesion molecules are addressed.  相似文献   

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Long-term ecological sites are 'listening places'– places where we press our ears to the earth and strain to hear its pulse. Such sites will be needed especially in coming decades, as ecosystems throughout the world face mounting stresses, mostly from human influences. My aim, in these musings, is to elicit conversation, by way of seven questions, about how best to look after the long-term sites, so that they remain intact, relevant, and enlightening for our successors, decades hence.  相似文献   

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While much of Medical Anthropology was and is what we can call “Normal” (following Kuhn) Medical Anthropology, I coined the term Millennial Medical Anthropology for that branch of the discipline that, in the 1990s, was departing from the Normal research paradigms and was deserving of a distinct sobriquet. This paper considers the Strong Program in Medical Anthropology’s Millennial Medical Anthropology and its key subdivisions, the Cultural Studies of Science and Cultural Bioethics. Specifically it considers Medical Anthropology’s movement from the past into an ethical future wherein Normal Biomedicine, Bioethics and Global Health are problematized. This provides the basis for the construction of a truly anthropological global health (i.e., Global, Global Health or Global Health 2.0).  相似文献   

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