13,048 research outputs found

    Power quality disturbances assessment during unintentional islanding scenarios. A contribution to voltage sag studies

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    This paper presents a novel voltage sag topology that occurs during an unintentional islanding operation (IO) within a distribution network (DN) due to large induction motors (IMs). When a fault occurs, following the circuit breaker (CB) fault clearing, transiently, the IMs act as generators due to their remanent kinetic energy until the CB reclosing takes place. This paper primarily contributes to voltage sag characterization. Therefore, this novel topology is presented, analytically modelled and further validated. It is worth mentioning that this voltage sag has been identified in a real DN in which events have been recorded for two years. The model validation of the proposed voltage sag is done via digital simulations with a model of the real DN implemented in Matlab considering a wide range of scenarios. Both simulations and field measurements confirm the voltage sag analytical expression presented in this paper as well as exhibiting the high accuracy achieved in the three-phase model adopted.Postprint (published version

    Neuroimaging as a selection tool and endpoint in preclinical and clinical trials

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    Standard imaging in acute stroke enables the exclusion of non-stroke structural CNS lesions and cerebral haemorrhage from clinical and pre-clinical ischaemic stroke trials. In this review, the potential benefit of imaging (e.g., angiography and penumbral imaging) as a translational tool for trial recruitment and the use of imaging endpoints are discussed for both clinical and pre-clinical stroke research. The addition of advanced imaging to identify a “responder” population leads to reduced sample size for any given effect size in phase 2 trials and is a potentially cost-efficient means of testing interventions. In pre-clinical studies, technical failures (failed or incomplete vessel occlusion, cerebral haemorrhage) can be excluded early and continuous multimodal imaging of the animal from stroke onset is feasible. Pre- and post-intervention repeat scans provide real time assessment of the intervention over the first 4–6 h. Negative aspects of advanced imaging in animal studies include increased time under general anaesthesia, and, as in clinical studies, a delay in starting the intervention. In clinical phase 3 trial designs, the negative aspects of advanced imaging in patient selection include higher exclusion rates, slower recruitment, overestimated effect size and longer acquisition times. Imaging may identify biological effects with smaller sample size and at earlier time points, compared to standard clinical assessments, and can be adjusted for baseline parameters. Mechanistic insights can be obtained. Pre-clinically, multimodal imaging can non-invasively generate data on a range of parameters, allowing the animal to be recovered for subsequent behavioural testing and/or the brain taken for further molecular or histological analysis

    The Welfare Implications of Non-Patentable Financial Innovations

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    Investment Banks invest in R&D to design innovative securities even when imitation is possible, i.e., when innovations cannot be patented. We show how a financial institution can profit from the development of financial products even if they are unpatentable. For certain types of financial products innovating investment banks have an information advantage over imitators. This information advantage makes them better competitors and market leaders. The mere possibility of costless imitation drives innovators’ profits down, but still keeps them positive. The absence of patents allows part of the surplus generated by the innovation to be allocated to investors. The extent of surplus sharing depends on the degree of asymmetry in the information owned by imitators and innovators and on the total number of innovators. The larger this asymmetry, the higher the innovator’s profits and the lower the investor’s surplus. With more than one innovator all the surplus goes to investors.Financial innovation, imperfect imitation, patents

    Designing application software in wide area network settings

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    Progress in methodologies for developing robust local area network software has not been matched by similar results for wide area settings. The design of application software spanning multiple local area environments is examined. For important classes of applications, simple design techniques are presented that yield fault tolerant wide area programs. An implementation of these techniques as a set of tools for use within the ISIS system is described

    Cytochrome c signalosome in mitochondria

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    Cytochrome c delicately tilts the balance between cell life (respiration) and cell death (apoptosis). Whereas cell life is governed by transient electron transfer interactions of cytochrome c inside the mitochondria, the cytoplasmic adducts of cytochrome c that lead to cell death are amazingly stable. Interestingly, the contacts of cytochrome c with its counterparts shift from the area surrounding the heme crevice for the redox complexes to the opposite molecule side when the electron flow is not necessary. The cytochrome c signalosome shows a higher level of regulation by post-translational modifications—nitration and phosphorylation—of the hemeprotein. Understanding protein interfaces, as well as protein modifications, would puzzle the mitochondrial cytochrome c-controlled pathways out and enable the design of novel drugs to silence the action of pro-survival and pro-apoptotic partners of cytochrome c.Spanish Ministry of Science and Innovation BFU2009-07190Andalusian Government BIO198 P08-CVI-387

    Wireless Broadband Access: Policy Implications of Heterogeneous Networks

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    A wireless heterogeneous network can help increase the access transmission speed and contribute thereby to the broadband deployment policies of administrations and telecommunications operators. Given the technical particularities of wireless heterogeneous networks, the deployment of wireless heterogeneous networks raises a number of challenges that need to be addressed by regulatory authorities. This article analyses the following regulatory implications: standardisation and technology neutrality, spectrum management, market analysis, open access and infrastructure sharing, interconnection pricing and charging, broadband deployment policies, and privacy and security issues. --4G,heterogeneous networks,cooperative networks,spectrum management,regulation,wireless networks

    Recommendations for reporting ion mobility Mass Spectrometry measurements

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    Here we present a guide to ion mobility mass spectrometry experiments, which covers both linear and nonlinear methods: what is measured, how the measurements are done, and how to report the results, including the uncertainties of mobility and collision cross section values. The guide aims to clarify some possibly confusing concepts, and the reporting recommendations should help researchers, authors and reviewers to contribute comprehensive reports, so that the ion mobility data can be reused more confidently. Starting from the concept of the definition of the measurand, we emphasize that (i) mobility values (K0) depend intrinsically on ion structure, the nature of the bath gas, temperature, and E/N; (ii) ion mobility does not measure molecular surfaces directly, but collision cross section (CCS) values are derived from mobility values using a physical model; (iii) methods relying on calibration are empirical (and thus may provide method‐dependent results) only if the gas nature, temperature or E/N cannot match those of the primary method. Our analysis highlights the urgency of a community effort toward establishing primary standards and reference materials for ion mobility, and provides recommendations to do so. © 2019 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc
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