7,622 research outputs found

    Guia para identificação dos principais solos do Estado do Paraná.

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    Conceitos e definições; Principais solos do Estado do Paraná.bitstream/item/36228/1/Guia-para-identificacao.pd

    Collaboration in the Semantic Grid: a Basis for e-Learning

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    The CoAKTinG project aims to advance the state of the art in collaborative mediated spaces for the Semantic Grid. This paper presents an overview of the hypertext and knowledge based tools which have been deployed to augment existing collaborative environments, and the ontology which is used to exchange structure, promote enhanced process tracking, and aid navigation of resources before, after, and while a collaboration occurs. While the primary focus of the project has been supporting e-Science, this paper also explores the similarities and application of CoAKTinG technologies as part of a human-centred design approach to e-Learning

    The VLT-FLAMES Tarantula Survey X: Evidence for a bimodal distribution of rotational velocities for the single early B-type stars

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    Aims: Projected rotational velocities (\vsini) have been estimated for 334 targets in the VLT-FLAMES Tarantula survey that do not manifest significant radial velocity variations and are not supergiants. They have spectral types from approximately O9.5 to B3. The estimates have been analysed to infer the underlying rotational velocity distribution, which is critical for understanding the evolution of massive stars. Methods: Projected rotational velocities were deduced from the Fourier transforms of spectral lines, with upper limits also being obtained from profile fitting. For the narrower lined stars, metal and non-diffuse helium lines were adopted, and for the broader lined stars, both non-diffuse and diffuse helium lines; the estimates obtained using the different sets of lines are in good agreement. The uncertainty in the mean estimates is typically 4% for most targets. The iterative deconvolution procedure of Lucy has been used to deduce the probability density distribution of the rotational velocities. Results: Projected rotational velocities range up to approximately 450 \kms and show a bi-modal structure. This is also present in the inferred rotational velocity distribution with 25% of the sample having 00\leq\ve\leq100\,\kms and the high velocity component having \ve250\sim 250\,\kms. There is no evidence from the spatial and radial velocity distributions of the two components that they represent either field and cluster populations or different episodes of star formation. Be-type stars have also been identified. Conclusions: The bi-modal rotational velocity distribution in our sample resembles that found for late-B and early-A type stars. While magnetic braking appears to be a possible mechanism for producing the low-velocity component, we can not rule out alternative explanations.Comment: to be publisged in A&

    Integrin beta 1 inhibition alleviates the chronic hyperproliferative dermatitis phenotype of SHARPIN-deficient mice

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    SHARPIN (Shank-Associated RH Domain-Interacting Protein) is a component of the linear ubiquitin chain assembly complex (LUBAC), which enhances TNF-induced NF-kappa B activity. SHARPIN-deficient (Sharpin(cpdm/cpdm)) mice display multi-organ inflammation and chronic proliferative dermatitis (cpdm) due to TNF-induced keratinocyte apoptosis. In cells, SHARPIN also inhibits integrins independently of LUBAC, but it has remained enigmatic whether elevated integrin activity levels in the dermis of Sharpin(cpdm/cpdm) mice is due to increased integrin activity or is secondary to inflammation. In addition, the functional contribution of increased integrin activation to the Sharpin(cpdm/cpdm) phenotype has not been investigated. Here, we find increased integrin activity in keratinocytes from Tnfr1(-/-) Sharpin(cpdm/cpdm) double knockout mice, which do not display chronic inflammation or proliferative dermatitis, thus suggesting that SHARPIN indeed acts as an integrin inhibitor in vivo. In addition, we present evidence for a functional contribution of integrin activity to the Sharpin(cpdm/cpdm) skin phenotype. Treatment with an integrin beta 1 function blocking antibody reduced epidermal hyperproliferation and epidermal thickness in Sharpin(cpdm/cpdm) mice. Our data indicate that, while TNF-induced cell death triggers the chronic inflammation and proliferative dermatitis, absence of SHARPIN-dependent integrin inhibition exacerbates the epidermal hyperproliferation in Sharpin(cpdm/cpdm) mice.Peer reviewe

    Unravelling social constructionism

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    Social constructionist research is an area of rapidly expanding influence that has brought together theorists from a range of different disciplines. At the same time, however, it has fuelled the development of a new set of divisions. There would appear to be an increasing uneasiness about the implications of a thoroughgoing constructionism, with some regarding it as both theoretically parasitic and politically paralysing. In this paper I review these debates and clarify some of the issues involved. My main argument is that social constructionism is not best understood as a unitary paradigm and that one very important difference is between what Edwards (1997) calls its ontological and epistemic forms. I argue that an appreciation of this distinction not only exhausts many of the disputes that currently divide the constructionist community, but also takes away from the apparent radicalism of much of this work
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