204 research outputs found

    Observations of far-infrared transitions between excited states of OH

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    In observations of the Kleinmann-Low Nebula were detected of Orion 84.42 and 84.60 micron transitions between the P-2 sub 3/2 and Pi-2 sub 3/2 (J = 5/2) levels of OH with respective fluxes of 1.0 + or - 0.3 to the minus 17th power and 1.4 + or - 0.4 x 10 to the minus 17th power W cm/sq. When compared to 119 micron flux levels of OH and 153 micron flux levels of these radicals by Viscuso, these results suggest appreciable self-absorption of OH line radiation within the Nebula. It is probable that the CO emission due to the J = 31 yields 30 rotational transition at 84.411 micron makes a substantial contribution to the observed 84.42 micron flux, and that it also is at least partially absorbed at the 84.42 micron OH transition frequency. The 88.55 and 88.78 micron (J = 9/2 to 7/2) transitions of CH also were sought, but yielded only to upper limits of 3 x 10 to the minus 18th power W /sq cm each. A search of W3-IRS5 yields upper limits to the 84.42 micron OH and 87.19 micron CO (J = 30 to 29) transitions of 2 x 10 minus 18th power W cm/2

    On the relative importance of thermal and chemical buoyancy in regular and impact-induced melting in a Mars-like planet

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    We ran several series of two-dimensional numerical mantle convection simulations representing in idealized form the thermochemical evolution of a Mars-like planet. In order to study the importance of compositional buoyancy of melting mantle, the models were set up in pairs of one including all thermal and compositional contributions to buoyancy and one accounting only for the thermal contributions. In several of the model pairs, single large impacts were introduced as causes of additional strong local anomalies, and their evolution in the framework of the convecting mantle was tracked. The models confirm that the additional buoyancy provided by the depletion of the mantle by regular melting can establish a global stable stratification of the convecting mantle and throttle crust production. Furthermore, the compositional buoyancy is essential in the stabilization and preservation of local compositional anomalies directly beneath the lithosphere and offers a possible explanation for the existence of distinct, long-lived reservoirs in the martian mantle. The detection of such anomalies by geophysical means is probably difficult, however; they are expected to be detected by gravimetry rather than by seismic or heat flow measurements. The results further suggest that the crustal thickness can be locally overestimated by up to ~20 km if impact-induced density anomalies in the mantle are neglected.Comment: 29 pages, 10 figure

    Physical Properties of Iron in the Inner Core

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    The Earth's inner core plays a vital role in the dynamics of our planet and is itself strongly exposed to dynamic processes as evidenced by a complex pattern of elastic structure. To gain deeper insight into the nature of these processes we rely on a characterization of the physical properties of the inner core which are governed by the material physics of its main constituent, iron. Here we review recent research on structure and dynamics of the inner core, focusing on advances in mineral physics. We will discuss results on core composition, crystalline structure, temperature,and various aspects of elasticity. Based on recent computational results, we will show that aggregate seismic properties of the inner core can be explained by temperature and compression effects on the elasticity of pure iron, and use single crystal anisotropy to develop a speculative textural model of the inner core that can explain major aspects of inner core anisotropy.Comment: 23 pages, 16 figures. To appear in AGU Geodynamics Series book on "Core structure, dynamics, and rotation", V. Dehant et al. (eds.

    “Embodying” dirty work: A review of the literature

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    This article reviews the growing literature on dirty work i.e. work that is seen as disgusting or degrading and argues for a more ‘embodied' understanding of such work. It points to a tendency in the literature to focus on the nature of the task or role and on social and moral dimensions of the work at the expense of its material and embodied aspects. The latter are discussed through three, interrelated themes: ‘embodied suitability' whereby forms of dirty work are seen as suitable for some ‘working bodies' and not for others; ‘staining' which is presented as both a material and a symbolic process; and the role of work practices in both supporting and undermining ideological constructions around the work. The article concludes by arguing for a more comprehensive approach which includes both the material and the symbolic into accounts of such work

    Polygenic susceptibility to prostate and breast cancer: implications for personalised screening

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    BACKGROUND: We modelled the efficiency of a personalised approach to screening for prostate and breast cancer based on age and polygenic risk-profile compared with the standard approach based on age alone.METHODS: We compared the number of cases potentially detectable by screening in a population undergoing personalised screening with a population undergoing screening based on age alone. Polygenic disease risk was assumed to have a log-normal relative risk distribution predicted for the currently known prostate or breast cancer susceptibility variants (N = 31 and N = 18, respectively).RESULTS: Compared with screening men based on age alone (aged 55-79: 10-year absolute risk >= 2%), personalised screening of men age 45-79 at the same risk threshold would result in 16% fewer men being eligible for screening at a cost of 3% fewer screen-detectable cases, but with added benefit of detecting additional cases in younger men at high risk. Similarly, compared with screening women based on age alone (aged 47-79: 10-year absolute risk >= 2.5%), personalised screening of women age 35-79 at the same risk threshold would result in 24% fewer women being eligible for screening at a cost of 14% fewer screen-detectable cases.CONCLUSION: Personalised screening approach could improve the efficiency of screening programmes. This has potential implications on informing public health policy on cancer screening. British Journal of Cancer (2011) 104, 1656 -1663. doi: 10.1038/bjc.2011.118 www.bjcancer.com Published online 5 April 2011 (C) 2011 Cancer Research U

    In search of the authentic nation: landscape and national identity in Canada and Switzerland

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    While the study of nationalism and national identity has flourished in the last decade, little attention has been devoted to the conditions under which natural environments acquire significance in definitions of nationhood. This article examines the identity-forming role of landscape depictions in two polyethnic nation-states: Canada and Switzerland. Two types of geographical national identity are identified. The first – what we call the ‘nationalisation of nature’– portrays zarticular landscapes as expressions of national authenticity. The second pattern – what we refer to as the ‘naturalisation of the nation’– rests upon a notion of geographical determinism that depicts specific landscapes as forces capable of determining national identity. The authors offer two reasons why the second pattern came to prevail in the cases under consideration: (1) the affinity between wild landscape and the Romantic ideal of pure, rugged nature, and (2) a divergence between the nationalist ideal of ethnic homogeneity and the polyethnic composition of the two societies under consideration

    Modulating Temporal and Spatial Oxygenation over Adherent Cellular Cultures

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    Oxygen is a key modulator of many cellular pathways, but current devices permitting in vitro oxygen modulation fail to meet the needs of biomedical research. A microfabricated insert for multiwell plates has been developed to more effectively control the temporal and spatial oxygen concentration to better model physiological phenomena found in vivo. The platform consists of a polydimethylsiloxane insert that nests into a standard multiwell plate and serves as a passive microfluidic gas network with a gas-permeable membrane aimed to modulate oxygen delivery to adherent cells. Equilibration time is on the order of minutes and a wide variety of oxygen profiles can be attained based on the device design, such as the cyclic profile achieved in this study, and even oxygen gradients to mimic those found in vivo. The proper biological consequences of the device's oxygen delivery were confirmed in cellular models via a proliferation assay and western analysis of the upregulation of hypoxia inducible transcription factor-1α. These experiments serve as a demonstration for the platform as a viable tool to increase experimental throughput and permit novel experimental possibilities in any biomedical research lab

    Pan-Cancer Analysis of lncRNA Regulation Supports Their Targeting of Cancer Genes in Each Tumor Context

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    Long noncoding RNAs (lncRNAs) are commonly dys-regulated in tumors, but only a handful are known toplay pathophysiological roles in cancer. We inferredlncRNAs that dysregulate cancer pathways, onco-genes, and tumor suppressors (cancer genes) bymodeling their effects on the activity of transcriptionfactors, RNA-binding proteins, and microRNAs in5,185 TCGA tumors and 1,019 ENCODE assays.Our predictions included hundreds of candidateonco- and tumor-suppressor lncRNAs (cancerlncRNAs) whose somatic alterations account for thedysregulation of dozens of cancer genes and path-ways in each of 14 tumor contexts. To demonstrateproof of concept, we showed that perturbations tar-geting OIP5-AS1 (an inferred tumor suppressor) andTUG1 and WT1-AS (inferred onco-lncRNAs) dysre-gulated cancer genes and altered proliferation ofbreast and gynecologic cancer cells. Our analysis in-dicates that, although most lncRNAs are dysregu-lated in a tumor-specific manner, some, includingOIP5-AS1, TUG1, NEAT1, MEG3, and TSIX, synergis-tically dysregulate cancer pathways in multiple tumorcontexts
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