5,412 research outputs found

    Clustering of vacancy defects in high-purity semi-insulating SiC

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    Positron lifetime spectroscopy was used to study native vacancy defects in semi-insulating silicon carbide. The material is shown to contain (i) vacancy clusters consisting of 4--5 missing atoms and (ii) Si vacancy related negatively charged defects. The total open volume bound to the clusters anticorrelates with the electrical resistivity both in as-grown and annealed material. Our results suggest that Si vacancy related complexes compensate electrically the as-grown material, but migrate to increase the size of the clusters during annealing, leading to loss of resistivity.Comment: 8 pages, 5 figure

    Insights into the Fallback Path of Best-Effort Hardware Transactional Memory Systems

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    DOI 10.1007/978-3-319-43659-3Current industry proposals for Hardware Transactional Memory (HTM) focus on best-effort solutions (BE-HTM) where hardware limits are imposed on transactions. These designs may show a significant performance degradation due to high contention scenarios and different hardware and operating system limitations that abort transactions, e.g. cache overflows, hardware and software exceptions, etc. To deal with these events and to ensure forward progress, BE-HTM systems usually provide a software fallback path to execute a lock-based version of the code. In this paper, we propose a hardware implementation of an irrevocability mechanism as an alternative to the software fallback path to gain insight into the hardware improvements that could enhance the execution of such a fallback. Our mechanism anticipates the abort that causes the transaction serialization, and stalls other transactions in the system so that transactional work loss is mini- mized. In addition, we evaluate the main software fallback path approaches and propose the use of ticket locks that hold precise information of the number of transactions waiting to enter the fallback. Thus, the separation of transactional and fallback execution can be achieved in a precise manner. The evaluation is carried out using the Simics/GEMS simulator and the complete range of STAMP transactional suite benchmarks. We obtain significant performance benefits of around twice the speedup and an abort reduction of 50% over the software fallback path for a number of benchmarks.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Herding cats: observing live coding in the wild

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    After a momentous decade of live coding activities, this paper seeks to explore the practice with the aim of situating it in the history of contemporary arts and music. The article introduces several key points of investigation in live coding research and discusses some examples of how live coding practitioners engage with these points in their system design and performances. In the light of the extremely diverse manifestations of live coding activities, the problem of defining the practice is discussed, and the question raised whether live coding will actually be necessary as an independent category

    Philosophy and updating of the asteroid photometric catalogue

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    The Asteroid Photometric Catalogue now contains photometric lightcurves for 584 asteroids. We discuss some of the guiding principles behind it. This concerns both observers who offer input to it and users of the product

    AN EVALUATION OF THE PERFORMANCE OF THE KOBE STRATEGY MATRIX: AN EXAMPLE BASED UPON A BIOMASS DYNAMIC ASSESSMENT MODEL

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    The main management objective of ICCAT is to maintain the populations of tuna and tuna-like fishes at levels which will permit the maximum sustainable catch. Scientific advice designed to meet this objective, in common with other tuna Regional Fisheries Management Organisations' (tRFMO) scientific committees is presented in the form of the Kobe II Strategy Matrix (K2SM). This is essentially a decision table showing the time taken to achieve management objectives (e.g., stock recovery) for different levels of TAC or effort. The role of the K2SM as an important tool to communicate efficiently among all stakeholders and to assist in the decision-making process according to different levels of risk has been recognised.JRC.G.4-Maritime affair

    Overvåking av forurensningssituasjonen i indre Oslofjord 1997

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    Vannkvaliteten i fjordens overflatelag sommeren 1997 var omtrent like bra som i 1996, som var et meget bra år sammenlignet med 1994 og 1995, hvor overløp og flom (1995) preget forholdene. Den milde vinteren var lite gunstig for dypvannsfornyelsen og det var meget liten vannfornyelse i Bunnefjorden. Det ble allikevel registrert oksygen i dypvannet selv om konsentrasjonene ble meget lave på høsten og klart lavere enn gjennomsnittlige forhold i perioden før det siste store anlegget med kjemisk rensing ble startet i 1982. I Vestfjorden var oksygenforholdene om høsten noe bedre. I Drøbaksundet ble det observert lave oksygenkonsentrasjoner sammenlignet med tidligere observasjoner, selv om nivået, som vanlig, var betydelig høyere enn i indre Oslofjord. Årsaken til de relativt lave oksygenkonsentrasjonene var en ekstra lang stagnasjonperiode. Observasjonene i 1997 bekrefter tidligere trender i fjordens forurensningsutvikling. Vannkvaliteten i overflatelaget har blitt bedre etter gjennomførte rensetiltak og det har vært en liten men positiv utvikling i dypvannet i Vestfjorden, men ikke i Bunnefjorden. På mellomdyp i Vestfjorden er det fortsatt ofte registrert dårligere oksygenforhold. De observerte forandringer skyldes ikke bare rensetiltak men også variasjoner i dypvannsfornyelser og andre klimaavhengige variasjoner

    A KOBE STRATEGY MAATRIX BASED UPON PROBABILISTIC REFERENCE POINTS: AN EXAMPLE USING A BIOMASS DYNAMIC ASSESSMENT MODEL

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    The main management objective of ICCAT is to maintain the populations of tuna and tuna-like fishes at levels which will permit the maximum sustainable catch. Scientific advice designed to meet this objective, in common with other tuna Regional Fisheries Management Organisations (tRFMO) scientific committees, is presented in the form of the Kobe II Strategy Matrix (K2SM). A decision table is given showing the time taken to achieve management objectives (e.g., stock recovery) for different levels of TAC or effort. However, substantial uncertainties still remain in assessments and therefore a key area of research is to show how uncertainty and improvements in information, consistent with the principles of the precautionary approach, can be incorporated into advice, so that for any level of uncertainty there is the same risk of depletion.JRC.G.4-Maritime affair
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