1,893 research outputs found

    Earthing The Spirit: With Mark Wallace

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    BlogForever D2.4: Weblog spider prototype and associated methodology

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    The purpose of this document is to present the evaluation of different solutions for capturing blogs, established methodology and to describe the developed blog spider prototype

    BlogForever D5.2: Implementation of Case Studies

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    This document presents the internal and external testing results for the BlogForever case studies. The evaluation of the BlogForever implementation process is tabulated under the most relevant themes and aspects obtained within the testing processes. The case studies provide relevant feedback for the sustainability of the platform in terms of potential users’ needs and relevant information on the possible long term impact

    BlogForever D5.3: User Questionnaires and Reports

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    This report presents the feedback gathered from third party users during the BlogForever Case Studies. Therefore, the research framework is defined and the case studies results are presented, followed by a summary of conclusions and remarks

    The thrombin receptor in adrenal medullary microvascular endothelial cells is negatively coupled to adenylyl cyclase through a Gi protein

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    AbstractThe effects of thrombin on adenylyl cyclase activity were examined in rat adrenal medullary microvascular endothelial cells (RAMEC). Confluent RAMEC monolayers were stimulated for 5 min with cAMP-generating agents in the absence and presence of thrombin, and intracellular cAMP was measured with a radioligand binding assay. Thrombin (0.001–0.25 U/ml) dose-dependently inhibited IBMX-, isoproterenol- and forskolin-stimulated cAMP accumulation. A peptide agonist of the thrombin receptor, γ-thrombin, and the serine proteases trypsin and plasmin, also inhibited agonist-stimulated cAMP levels, while proteolytically inactive PPACK- or DIP-α-thrombins were without effect. Moreover, the thrombin inhibitor hirudin abolished the inhibitory effect of thrombin but not of the peptide agonist. These results suggest that the inhibitory action of thrombin on cAMP accumulation is mediated by a proteolytically-activated thrombin receptor. The inhibitor of Gi-proteins pertussis toxin abolished the inhibitory effect of thrombin on isoproterenol- or IBMX-stimulated cAMP production, while the phorbol ester PMA partly impaired it. The protein kinase C inhibitors staurosporine or H7 and the intracellular Ca2+ chelator BAPTA-AM were without effect. Collectively, our data suggest that the thrombin receptor in RAMEC is negatively coupled to adenylyl cyclase through a pertussis toxin-sensitive Gi-protein

    A grid-based infrastructure for distributed retrieval

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    In large-scale distributed retrieval, challenges of latency, heterogeneity, and dynamicity emphasise the importance of infrastructural support in reducing the development costs of state-of-the-art solutions. We present a service-based infrastructure for distributed retrieval which blends middleware facilities and a design framework to ‘lift’ the resource sharing approach and the computational services of a European Grid platform into the domain of e-Science applications. In this paper, we give an overview of the DILIGENT Search Framework and illustrate its exploitation in the field of Earth Science

    Proton-counting radiography for proton therapy: a proof of principle using CMOS APS technology

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    Despite the early recognition of the potential of proton imaging to assist proton therapy (Cormack 1963 J. Appl. Phys. 34 2722), the modality is still removed from clinical practice, with various approaches in development. For proton-counting radiography applications such as computed tomography (CT), the water-equivalent-path-length that each proton has travelled through an imaged object must be inferred. Typically, scintillator-based technology has been used in various energy/range telescope designs. Here we propose a very different alternative of using radiation-hard CMOS active pixel sensor technology. The ability of such a sensor to resolve the passage of individual protons in a therapy beam has not been previously shown. Here, such capability is demonstrated using a 36 MeV cyclotron beam (University of Birmingham Cyclotron, Birmingham, UK) and a 200 MeV clinical radiotherapy beam (iThemba LABS, Cape Town, SA). The feasibility of tracking individual protons through multiple CMOS layers is also demonstrated using a two-layer stack of sensors. The chief advantages of this solution are the spatial discrimination of events intrinsic to pixelated sensors, combined with the potential provision of information on both the range and residual energy of a proton. The challenges in developing a practical system are discussed

    Dynamics of quantum systems

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    A relation between the eigenvalues of an effective Hamilton operator and the poles of the SS matrix is derived which holds for isolated as well as for overlapping resonance states. The system may be a many-particle quantum system with two-body forces between the constituents or it may be a quantum billiard without any two-body forces. Avoided crossings of discrete states as well as of resonance states are traced back to the existence of branch points in the complex plane. Under certain conditions, these branch points appear as double poles of the SS matrix. They influence the dynamics of open as well as of closed quantum systems. The dynamics of the two-level system is studied in detail analytically as well as numerically.Comment: 21 pages 7 figure

    Effect of the anisotropy on the glory structure of molecule-molecule scattering cross sections

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    Total (elastic + rotationally inelastic) integral cross sections are computed for O2(3Σg)_2(^3\Sigma_g^-)-O2(3Σg)_2(^3\Sigma_g^-) using a recent ab initio potential energy surface. The sampled velocity range allows us a thorough comparison of the glory interference pattern observed in molecular beam experiments. The computed cross sections are about 10% smaller than the measured ones, however, a remarkable agreement in the velocity positions of the glory extrema is achieved. By comparing with models where the anisotropy of the interaction is reduced or removed, it is found that the glory pattern is very sensitive to the anisotropy, especially the positions of the glory extrema.Comment: 13 pages, 3 figure
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