465 research outputs found

    Resonant Photoelectron Diffraction with circularly polarized light

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    Resonant angle scanned x-ray photoelectron diffraction (RXPD) allows the determination of the atomic and magnetic structure of surfaces and interfaces. For the case of magnetized nickel the resonant L2 excitation with circularly polarized light yields electrons with a dichroic signature from which the dipolar part may be retrieved. The corresponding L2MM and L3MM Auger electrons carry different angular momenta since their source waves rotate the dichroic dipole in the electron emission patterns by distinct angles

    Controlling Disk Contention for Parallel Query Processing in Shared Disk Database Systems

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    Shared Disk database systems offer a high flexibility for parallel transaction and query processing. This is because each node can process any transaction, query or subquery because it has access to the entire database. Compared to Shared Nothing, this is particularly advantageous for scan queries for which the degree of intra-query parallelism as well as the scan processors themselves can dynamically be chosen. On the other hand, there is the danger of disk contention between subqueries, in particular for index scans. We present a detailed simulation study to analyze the effectiveness of parallel scan processing in Shared Disk database systems. In particular, we investigate the relationship between the degree of declustering and the degree of scan parallelism for relation scans, clustered index scans, and non-clustered index scans. Furthermore, we study the usefulness of disk caches and prefetching for limiting disk contention. Finally, we show the importance of dynamically choosing the degree of scan parallelism to control disk contention in multi-user mode

    Analysis of parallel scan processing in Shared Disk database systems

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    Shared Disk database systems offer a high flexibility for parallel transaction and query processing. This is because each node can process any transaction, query or subquery because it has access to the entire database. Compared to Shared Nothing database systems, this is particularly advantageous for scan queries for which the degree of intra-query parallelism as well as the scan processors themselves can dynamically be chosen. On the other hand, there is the danger of disk contention between subqueries, in particular for index scans. We present a detailed simulation study to analyze the effectiveness of parallel scan processing in Shared Disk database systems. In particular, we investigate the relationship between the degree of declustering and the degree of scan parallelism for relation scans, clustered index scans, and non-clustered index scans. Furthermore, we study the usefulness of disk caches and prefetching for limiting disk contention. Finally, we show that disk contention in multi-user mode can be limited for Shared Disk database systems by dynamically choosing the degree of scan parallelism

    The Effect of Preterm Birth on Maximal Aerobic Exercise Capacity and Lung Function in Healthy Adults: A Systematic Review and Meta-analysis

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    Background: A negative impact of premature birth on health in adulthood is well established. However, it is not clear whether healthy adults who were born prematurely but have similar physical activity levels compared to adults born at term have a reduced maximal aerobic exercise capacity (maximum oxygen consumption [VO2max]). Objective: We aimed to determine the effect of premature birth on aerobic exercise capacity and lung function in otherwise healthy, physically active individuals. Methods: A broad literature search was conducted in the PubMed database. Search terms included ‘preterm/premature birth’ and ‘aerobic exercise capacity’. Maximal oxygen consumption (mL/kg/min) was the main variable required for inclusion, and amongst those investigations forced expiratory volume in 1 s (FEV1, % predicted) was evaluated as a secondary parameter. For the systematic review, 29 eligible articles were identified. Importantly, for the meta-analysis, only studies which reported similar activity levels between healthy controls and the preterm group/s were included, resulting in 11 articles for the VO2max analysis (total n = 688, n = 333 preterm and n = 355 controls) and six articles for the FEV1 analysis (total n = 296, n = 147 preterm and n = 149 controls). Data were analysed using Review Manager (Review Manager. RevMan version 5.4 software. The Cochrane Collaboration; 2020.). Results: The systematic review highlighted the broad biological impact of premature birth. While the current literature tends to suggest that there may be a negative impact of premature birth on both VO2max and FEV1, several studies did not control for the potential influence of differing physical activity levels between study groups, thus justifying a focused meta-analysis of selected studies. Our meta-analysis strongly suggests that prematurely born humans who are otherwise healthy do have a reduced VO2max (mean difference: − 4.40 [95% confidence interval − 6.02, − 2.78] mL/kg/min, p < 0.00001, test for overall effect: Z = 5.32) and FEV1 (mean difference − 9.22 [95% confidence interval − 13.54, − 4.89] % predicted, p < 0.0001, test for overall effect: Z = 4.18) independent of physical activity levels. Conclusions: Whilst the current literature contains mixed findings on the effects of premature birth on VO2max and FEV1, our focused meta-analysis suggests that even when physical activity levels are similar, there is a clear reduction in VO2max and FEV1 in adults born prematurely. Therefore, future studies should carefully investigate the underlying determinants of the reduced VO2max and FEV1 in humans born preterm, and develop strategies to improve their maximal aerobic capacity and lung function beyond physical activity interventions

    Antinociceptive efficacy of lacosamide in the monosodium iodoacetate rat model for osteoarthritis pain

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    The etiology of osteoarthritis is multifactorial, with inflammatory, metabolic, and mechanical causes. Pain in osteoarthritis is initiated by mild intra-articular inflammation and degeneration of articular cartilage and subchondral bone. The principle of treatment with acetaminophen or non-steroidal anti-inflammatory drugs is to reduce pain and improve joint function. Recently, animal models for osteoarthritic pain behavior have been established. The most frequently used rat model for analyzing properties of drugs on the pathology of osteoarthritis is the injection of the metabolic inhibitor monosodium iodoacetate into the joint, which inhibits the activity of glyceraldehyde-3-phosphate dehydrogenase in chondrocytes. Here, we characterize the effect on pain behavior of lacosamide, a member of a family of functionalized amino acids that are analogues of endogenous amino acids and D-serine, in the monosodium iodoacetate rat model for osteoarthritis in comparison to diclofenac and morphine. Lacosamide (3, 10, and 30 mg/kg) was able to reduce secondary mechanical allodynia and hyperalgesia similarly to morphine (3 mg/kg). In contrast, diclofenac (30 mg/kg) was only effective in reducing secondary mechanical hyperalgesia. During the first week, pain is induced mainly by inflammation in the iodoacetate model, but afterwards inflammation plays only a minor role in pain. Lacosamide was able to inhibit pain at days 3, 7 and 14 after induction of arthritis. This shows that lacosamide is able to reduce pain behavior induced by multiple mechanisms in animals

    „Der Freiheitskampf“

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    The National Socialist newspaper “Der Freiheitskampf” was published nearly daily from August 1st 1930 to Mai 8th 1945. In addition to articles from all areas of politics, economics and society, it contained information on dates, events and persons of regional importance in Saxony during the era of the Third Reich and before. Because of its character as official press organ of the NSDAP in the Gau Saxony, the newspaper is suitable to compensate missing historical evidence caused by the systematic shredding of files in spring 1945 and a lack of documents in Saxon archives. This paper presents a joint project of the Hannah Arendt Institute for the Research on Totalitarianism at the TU Dresden (HAIT) and the Saxon State and University Library, Dresden (SLUB), which aims to enhance the usability of “Der Freiheitskampf” – not only for scientific purposes. The combined digitization of the (nearly) complete source and its deep indexing result in a presentation in an elaborated database (the years 1930 to 1934 are covered at present). This database provides more effective possibilities for answering scientific (interdisciplinary) questions, not only on the establishment of National Socialist rulership in Saxony. The paper also discusses the possible worth of the usage of the newspaper and its representation in a database for purposes of political education

    Analytische Bestimmung einer Datenallokation fĂŒr Parallele Data Warehouses

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    Die stark wachsende Bedeutung der Analyse von Data Warehouse-Inhalten und bequemere Anfrageschnittstellen fĂŒr Endbenutzer erhöhen das Aufkommen an OLAP-Queries signifikant. Bei der Reduktion des Arbeitsumfanges und dem Erreichen kurzer Antwortzeiten fĂŒr diese komplexen Anfragen ist neben der Nutzung von Verarbeitungs- und I/O-ParallelitĂ€t eine adĂ€quate Datenallokation der SchlĂŒssel zu guter LeistungsfĂ€higkeit. Allerdings ist die Bestimmung einer geeigneten Fragmentierung und Allokation fĂŒr große Datenmengen, wie sie z.B. in Form von Faktentabellen oder Indexstrukturen in relationalen Sternschemas vorliegen, ein schwieriges Problem. HierfĂŒr existiert heutzutage praktisch keine WerkzeugunterstĂŒtzung. Wir prĂ€sentieren daher einen Ansatz zur analytischen Bestimmung einer passenden multi-dimensionalen, hierarchischen Datenallokation. Unser Ansatz dĂŒrfte recht einfach in ein Werkzeug zur automatischen UnterstĂŒtzung des Allokationsproblems integriert werden können
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