141 research outputs found

    A direct D-bar reconstruction algorithm for recovering a complex conductivity in 2-D

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    A direct reconstruction algorithm for complex conductivities in W2,(Ω)W^{2,\infty}(\Omega), where Ω\Omega is a bounded, simply connected Lipschitz domain in R2\mathbb{R}^2, is presented. The framework is based on the uniqueness proof by Francini [Inverse Problems 20 2000], but equations relating the Dirichlet-to-Neumann to the scattering transform and the exponentially growing solutions are not present in that work, and are derived here. The algorithm constitutes the first D-bar method for the reconstruction of conductivities and permittivities in two dimensions. Reconstructions of numerically simulated chest phantoms with discontinuities at the organ boundaries are included.Comment: This is an author-created, un-copyedited version of an article accepted for publication in [insert name of journal]. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at 10.1088/0266-5611/28/9/09500

    An integral equation method for the inverse conductivity problem

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    We present an image reconstruction algorithm for the Inverse Conductivity Problem based on reformulating the problem in terms of integral equations. We use as data the values of injected electric currents and of the corresponding induced boundary potentials, as well as the boundary values of the electrical conductivity. We have used a priori information to find a regularized conductivity distribution by first solving a Fredholm integral equation of the second kind for the Laplacian of the potential, and then by solving a first order partial differential equation for the regularized conductivity itself. Many of the calculations involved in the method can be achieved analytically using the eigenfunctions of an integral operator defined in the paper.Comment: 15 pages, 8 figure

    "The City Will be Ours: We Have So Decided": Circulating knowledges in a feminist register

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    This article juxtaposes insights from recent urban policy mobilities scholarship on circulating knowledges with an

    Assessment of the role of transcript for GATA-4 as a marker of unfavorable outcome in human adrenocortical neoplasms

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    BACKGROUND: Malignant neoplasia of the adrenal cortex is usually associated with very poor prognosis. When adrenocortical neoplasms are diagnosed in the early stages, distinction between carcinoma and adenoma can be very difficult to accomplish, since there is yet no reliable marker to predict tumor recurrence or dissemination. GATA transcription factors play an essential role in the developmental control of cell fate, cell proliferation and differentiation, organ morphogenesis, and tissue-specific gene expression. Normal mouse adrenal cortex expresses GATA-6 while its malignant counterpart only expresses GATA-4. The goal of the present study was to assess whether this reciprocal change in the expression of GATA factors might be relevant for predicting the prognosis of human adrenocortical neoplasms. Since human adrenal cortices express luteinizing hormone (LH/hCG) receptor and the gonadotropins are known to up-regulate GATA-4 in gonadal tumor cell lines, we also studied the expression of LH/hCG receptor. METHODS: We conducted a study on 13 non-metastasizing (NM) and 10 metastasizing/recurrent (MR) tumors obtained from a group of twenty-two adult and pediatric patients. The expression of GATA-4, GATA-6, and LH/hCG receptor (LHR) in normal and tumoral human adrenal cortices was analysed using reverse transcriptase-polymerase chain reaction (RT-PCR) complemented by dot blot hybridization. RESULTS: Messenger RNA for GATA-6 was detected in normal adrenal tissue, as well as in the totality of NM and MR tumors. GATA-4, by its turn, was detected in normal adrenal tissue, in 11 out of 13 NM tumors, and in 9 of the 10 MR tumors, with larger amounts of mRNA found among those presenting aggressive clinical behavior. Transcripts for LH receptor were observed both in normal tissue and neoplasms. A more intense LHR transcript accumulation was observed on those tumors with better clinical outcome. CONCLUSION: Our data suggest that the expression of GATA-6 in human adrenal cortex is not affected by tumorigenesis. GATA-4 expression is more abundant in MR tumors, while NM tumors express more intensely LHR. Further studies with larger cohorts are needed to test whether relative expression levels of LHR or GATA-4 might be used as prognosis predictors

    Synchronous communication in PLM environments using annotated CAD models

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    The connection of resources, data, and knowledge through communication technology plays a vital role in current collaborative design methodologies and Product Lifecycle Management (PLM) systems, as these elements act as channels for information and meaning. Despite significant advances in the area of PLM, most communication tools are used as separate services that are disconnected from existing development environments. Consequently, during a communication session, the specific elements being discussed are usually not linked to the context of the discussion, which may result in important information getting lost or becoming difficult to access. In this paper, we present a method to add synchronous communication functionality to a PLM system based on annotated information embedded in the CAD model. 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    Do público e do privado: uma perspectiva de género sobre uma dicotomia moderna

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    Neste texto propomos uma interpretação crítica da dicotomia histórica entre público e privado como dinâmica fundamental da modernidade. A partir de uma perspectiva de género, discutimos as fronteiras construídas entre espaço coletivo de cidadania e de sociabilidade e espaço individual de intimidade e desigualdade. Argumentamos a favor de uma relação de cumplicidade, ainda que tensa, entre as duas esferas, observando que a vida privada foi, em grande medida, moldada pelas mudanças operadas na vida pública. Recorrendo a diferentes definições de "público", notamos que, à medida que as sociabilidades tradicionais, essencialmente masculinas, estudadas entre outros por Ariès ou Sennett, sofriam uma erosão, crescia o sentimento de intimidade, aumentando igualmente a inclusão do privado no público através do alargamento da cidadania, em consequência das lutas travadas na esfera pública por vários movimentos de emancipação, como o operário ou o feminista. À medida que a pessoa era retirada da comunidade, do clã, do grupo de parentesco, em que eram "naturais" as desigualdades, no sentido aristotélico do termo, ia-se reencontrando progressivamente como indivíduo portador de cidadania. Se o espaço privado se tornou central na definição de uma identidade, ele é também crescentemente atravessado por mecanismos públicos de regulação. Nesse sentido, o movimento de ascensão do privado, que nas últimas décadas tem ocupado espaço de debate, deve ser cuidadosamente reinterpretado

    Fetal and infant origins of asthma

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    Previous studies have suggested that asthma, like other common diseases, has at least part of its origin early in life. Low birth weight has been shown to be associated with increased risks of asthma, chronic obstructive airway disease, and impaired lung function in adults, and increased risks of respiratory symptoms in early childhood. The developmental plasticity hypothesis suggests that the associations between low birth weight and diseases in later life are explained by adaptation mechanisms in fetal life and infancy in response to various adverse exposures. Various pathways leading from adverse fetal and infant exposures to growth adaptations and respiratory health outcomes have been studied, including fetal and early infant growth patterns, maternal smoking and diet, children’s diet, respiratory tract infections and acetaminophen use, and genetic susceptibility. Still, the specific adverse exposures in fetal and early postnatal life leading to respiratory disease in adult life are not yet fully understood. Current studies suggest that both environmental and genetic factors in various periods of life, and their epigenetic mechanisms may underlie the complex associations of low birth weight with respiratory disease in later life. New well-designed epidemiological studies are needed to identify the specific underlying mechanisms. This review is focused on specific adverse fetal and infant growth patterns and exposures, genetic susceptibility, possible respiratory adaptations and perspectives for new studies

    Action to achieve smoke-free homes- an exploration of experts' views

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    Background: Smoking in the home is the major cause of exposure to second-hand smoke in children in the UK, particularly those living in low income households which have fewer restrictions on smoking in the home. Reducing children's exposure to second-hand smoke is an important public health and inequalities issue. Drawing on findings from a qualitative Scottish study, this paper identifies key issues and challenges that need to be considered when developing action to promote smoke-free homes at the national and local level. Methods: Two panels of tobacco control experts (local and national) from Scotland considered the implications of the findings from a qualitative study of smokers and non-smokers (who were interviewed about smoking in the home), for future action on reducing smoking in the home. Results: Several key themes emerged through the expert panel discussions. These related to: improving knowledge about SHS among carers and professionals; the goal and approach of future interventions (incremental/harm reduction or total restrictions); the complexity of the interventions; and issues around protecting children. Conclusion: The expert panels were very aware of the sensitivities around the boundary between the 'private' home and public health interventions; but also the lack of evidence on the relative effectiveness of specific individual and community approaches on increasing restrictions on smoking in the home. Future action on smoke-free homes needs to consider and address these complexities. In particular health professionals and other key stakeholders need appropriate training on the issues around smoking in the home and how to address these, as well as for more research to evaluate interventions and develop a more robust evidence base to inform effective action on this issue
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