428 research outputs found

    Controlling Silver Nanoparticle Size and Morphology with Photostimulated Synthesis

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    Photo-induced synthesis and control over the size and shape of colloidal silver nanoparticles is investigated in contrast to photo-stimulated aggregation of small nanoparticles into large fractal-type structures. The feasibility of light-driven nanoengineering which enables manipulation of the sizes and shapes of the isolated nanoparticles is studied by varying the amount and type of the stabilizing agent and the type of optical irradiation.Comment: 10 pages, 7 figures, 11 image

    Molecular Image Analysis: Quantitative Description and Classification of the Nuclear Lamina in Human Mesenchymal Stem Cells

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    The nuclear lamina is an intermediate filament network that provides a structural framework for the cell nucleus. Changes in lamina structure are found during changes in cell fate such as cell division or cell death and are associated with human diseases. An unbiased method that quantifies changes in lamina shape can provide information on cells undergoing changes in cellular functions. We have developed an image processing methodology that finds and quantifies the 3D structure of the nuclear lamina. We show that measurements on such images can be used for cell classification and provide information concerning protein spatial localization in this structure. To demonstrate the efficacy of this method, we compared the lamina of unmanipulated human mesenchymal stem cells (hMSCs) at passage 4 to cells activated for apoptosis. A statistically significant classification was found between the two populations

    Poly(A)+ RNAs roam the cell nucleus and pass through speckle domains in transcriptionally active and inactive cells

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    Many of the protein factors that play a role in nuclear export of mRNAs have been identified, but still little is known about how mRNAs are transported through the cell nucleus and which nuclear compartments are involved in mRNA transport. Using fluorescent 2'O-methyl oligoribonucleotide probes, we investigated the mobility of poly(A)+ RNA in the nucleoplasm and in nuclear speckles of U2OS cells. Quantitative analysis of diffusion using photobleaching techniques revealed that the majority of poly(A)+ RNA move throughout the nucleus, including in and out of speckles (also called SC-35 domains), which are enriched for splicing factors. Interestingly, in the presence of the transcription inhibitor 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole, the association of poly(A)+ RNA with speckles remained dynamic. Our results show that RNA movement is energy dependent and that the proportion of nuclear poly(A)+ RNA that resides in speckles is a dynamic population that transiently interacts with speckles independent of the transcriptional status of the cell. Rather than the poly(A)+ RNA within speckles serving a stable structural role, our findings support the suggestion of a more active role of these regions in nuclear RNA metabolism and/or transport

    Evidence of Combat in Triceratops

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    Background: The horns and frill of Triceratops and other ceratopsids (horned dinosaurs) are interpreted variously as display structures or as weapons against conspecifics and predators. Lesions (in the form of periosteal reactive bone, healing fractures, and alleged punctures) on Triceratops skulls have been used as anecdotal support of intraspecific combat similar to that in modern horned and antlered animals. If ceratopsids with different cranial morphologies used their horns in such combat, this should be reflected in the rates of lesion occurrence across the skull. Methodology/Principal Findings: We used a G-test of independence to compare incidence rates of lesions in Triceratops (which possesses two large brow horns and a smaller nasal horn) and the related ceratopsid Centrosaurus (with a large nasal horn and small brow horns), for the nasal, jugal, squamosal, and parietal bones of the skull. The two taxa differ significantly in the occurrence of lesions on the squamosal bone of the frill (P = 0.002), but not in other cranial bones (P.0.20). Conclusions/Significance: This pattern is consistent with Triceratops using its horns in combat and the frill being adapted as a protective structure for this taxon. Lower pathology rates in Centrosaurus may indicate visual rather than physical use o

    “Pleasure stolen from the poor”: community discourse on the ‘theft’ of a Banksy

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    The removal of street art from community walls for private auction is a morally problematic yet legal action. This paper examines community reactions to the removal of Banksy’s No Ball Games for private auction. 500 unique reader comments on online newspaper articles reporting this controversial event were collected and analysed. An emerging set of urban moral codes was used to position street art as a valuable community asset rather than as an index of crime and social decay. An older discourse depicted No Ball Games as unlawful graffiti that was rightfully removed. Here, the operations of ‘the police’ (Rancière, 1999) in the distribution of the sensible are evident in the assertions that validate and depoliticize the removal of No Ball Games. This repertoire was used to attribute responsibility for the work’s removal to deterministic external forces, while reducing the accountability attributable to those responsible for the removal of the work. A contrasting anti removal repertoire depicted street art as a gift to the community, and its removal as a form of theft, and a source of harm to the community. The pro-removal repertoire incorporates and depoliticizes elements of the anti-removal repertoire, by acknowledging the moral wrong of the removal, but yielding to the legal rights of the wall owners to sell the work; and by recognizing the status of street art as valuable, but asserting that the proper place for art is a museum. The anti-removal repertoire counters elements of the pro-removal repertoire, by acknowledging the illegality of street art, but containing this to the initial act of making unsanctioned marks on a wall, after which point the work becomes the property of the community it is located within. This analysis reveals an emergent set of urban moral codes that positions a currently legal action as a form of criminal activity

    The 'reach' of Digital Language Archives: towards criteria for evaluation

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    Over the last decade, and with the help of digital media and technologies, archives (with the focus here on archives for endangered and minority languages) have extended their focus from preservation to also becoming facilities for dissemination. Their innovations have largely been on ‘discovery’: firstly by encouraging digitisation and inclusion of analogue and obscure materials, and by partnership with funding institutions to support the creation of new, ‘born digital’ language resources; and secondly through online provision of language resources via web catalogues driven by standardised metadata and in some cases providing enhanced discovery through web portals aggregating the holdings of multiple archives. These advances have increased the visibility, relevance and authority of archives for language-related disciplines and for language-speaker communities. This paper considers a broader set of parameters describing the ‘reach’ of archives, where ‘reach’ includes (a) archives’ understanding of their key audiences in order to provide appropriate services for them, e.g. identifying a range of relevant audiences, their languages of access, their varied technological and information literacies, interface design and usability; (b) discovery, drawing on the understandings of audiences in order to help them browse, navigate, search, identify and select their items of interest; (c) delivery, i.e. making available selected resources according to users’ preferences whether by download, view-in-browser, through apps or other means; (d) access management such that resource delivery follows depositors’ and communities’ preferences, and where users have ways of applying for and negotiating for access; (e) information accessibility, where the actual desired content is accessible to users, whether in terms of contextualisation or appropriate complexity, language, or modality; and finally (f) feedback channels, where users can utilise the archive to provide feedback to depositors or to enhance deposits with user-generated content. Through considering how a number of archives are providing such services, we can see their transition from repositories of memory to facilities for fostering participation and understanding
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