888 research outputs found

    The effect of addition of a third component on the behaviour of the lithium doped magnesium catalysts for the oxidative dehydrogenation of ethane

    Get PDF
    The oxidative dehydrogenation of ethane was studied with the use of promoted Li/MgO catalysts at temperatures of 600¿650°C. The addition of known promoters, cobalt and tin, gave a slight Increase In activity but a strong decrease in selectivity to ethylene under the conditions used. The addition of sodium improved the selectivity to ethylene and suppressed the formation of carbon monoxide. Using a feed of 12 vol% ethane and 6 vol% oxygen, the U/Na/MgO catalyst with 3.2wt% sodium showed a selectivity of 86 % to ethylene at 38 % conversion of ethane; the Li/MgO catalyst showed a selectivity of 80 % at similar conversions Thermal Investigations of the Li/Na/MgO catalyst showed that an eutectic melt of LINaCO3 is formed at 490°C; the existence of this molten phase is probably the cause of the Increased selectivity

    Plant collections for saltland revegetation and soil conservation

    Get PDF
    In 1967, during an overseas plant exploration trip, seeds of plants of reputed salt tolerance and forage value were obtained from seven countries. Since 1971, over 600 plants have been added to the original collection of 343 plants already under observation for suitability for forage production in saline and arid areas. Additions to the test programme since 1971, include shrubs from Algeria; Argentina; Australia; Chile; England; Iran; Israel; Libya; Morocco; Netherlands; Russia; South Africa; Spain; Tunis and the United States of America. This Bulletin includes details of all plant collections from 1966 to December 1983

    Theoristen versus behavioristen

    Get PDF
    The development of a strict methodology of observation and analysis in social science has always met with resistance. In the current debate on this topic in the United States two positions can be distinguished. There are the ’theorists’, who find their inspiration in the work of recent philosophers such as Marcuse and Sartre; they rate the formation of a political theory as a first priority. And there are the ’behaviorists’, whose first care is for scientific method. This contrast is reviewed on the basis of the document Political science at Berkeley, which was published anonimously by a group of students. The criticism of these students can be summarized under the headings ’commitment and ’relevance’. As far as commitment is concerned the critics reproach the behaviorists for not taking stands in important contemporary moral issues, and for identifying with the status quo. The author argues that what leads to acceptance of and identification with the existing political order, is not behaviorist methodology as such, but rather the mood of die behaviorists. As far as ’relevance’ is concerned, the critics are impatient with the futile detail analysis and data collecting of the behaviorists. The behaviorists’ use of a strict methodology of explanation by generalisation, leads to a reduction of the scope of analysis. And then only the ’easy’ aspects (’easy’ to quantify, ’easy’ to collect, etc.) are analyzed, and discontinuous developments are neglected. The author argues that the lack of a dynamic theory of the political process is an impediment indeed for political science, but that, again, behaviorism as such cannot he accused of being ’conservative’ or ’conformistic’: the refutation of race theories for example was rather a radical undertaking. It is concluded that for the time being it is not necessary to lay other hounds on political science than those that follow from the claims of rational debate and intellectual honesty

    Cut-Off Points for Mild, Moderate, and Severe Pain on the Numeric Rating Scale for Pain in Patients with Chronic Musculoskeletal Pain: Variability and Influence of Sex and Catastrophizing

    Get PDF
    Objectives. The 0 – 10 Numeric Rating Scale (NRS) is often used in pain management. The aims of our study were to determine the cut-off points for mild, moderate and severe pain in terms of pain-related interference with functioning in patients with chronic musculoskeletal pain, to measure the variability of the optimal cut-off points, and to determine the influence of patients’ catastrophizing and their sex on these cut-off points. Methods. 2854 patients were included. Pain was assessed by the NRS, functioning by the Pain Disability Index (PDI) and catastrophizing by the Pain Catastrophizing Scale (PCS). Cut-off point schemes were tested using ANOVAs with and without using the PSC scores or sex as co-variates and with the interaction between CP scheme and PCS score and sex, respectively. The variability of the optimal cut-off point schemes was quantified using bootstrapping procedure. Results and conclusion. The study showed that NRS scores ≤5 correspond to mild, scores of 6-7 to moderate and scores ≥8 to severe pain in terms of pain-related interference with functioning. Bootstrapping analysis identified this optimal NRS cut-off point scheme in 90 % of the bootstrapping samples. The interpretation of the NRS is independent of sex, but seems to depend on catastrophizing. In patients with high catastrophizing tendency, the optimal cut-off point scheme equals that for the total study sample, but in patients with a low catastrophizing tendency, NRS scores ≤3 correspond to mild, scores of 4-6 to moderate and scores ≥7 to severe pain in terms of interference with functioning. In these optimal cut-off schemes, NRS scores of 4 and 5 correspond to moderate interference with functioning for patients with low catastrophizing tendency and to mild interference for patients with high catastrophizing tendency. Theoretically one would therefore expect that among the patients with NRS scores 4 and 5 there would be a higher average PDI score for those with low catastrophizing than for those with high catastrophizing. However, we found the opposite. The fact that we did not find the same optimal CP scheme in the subgroups with lower and higher catastrophizing tendency may be due to chance variability

    Oseltamivir-resistant influenza A(H1N1)pdm09 virus in Dutch travellers returning from Spain, August 2012

    Get PDF
    Two Dutch travellers were infected with oseltamivirresistant influenza A(H1N1)pdm09 viruses with an H275Y neuraminidase substitution in early August 2012. Both cases were probably infected during separate holidays at the Catalonian coast (Spain). No epidemiological connection between the two cases was found, and neither of them was treated with oseltamivir before specimen collection. Genetic analysis of the neuraminidase gene revealed the presence of previously described permissive mutations that may increase the likelihood of such strains emerging and spreading widely

    Coalition theories: empirical evidence for dutch municipalities

    Get PDF
    The paper analyzes coalition formation in Dutch municipalities. After discussing the main features of the institutional setting, several theories are discussed, which are classified as size oriented, policy oriented and actor oriented models. A test statistic is proposed to determine the predictive power of these models. The empirical analysis shows that strategic positions as well as some of the distinguished preferences are important in the setting of Dutch municipalities. Especially, the dominant minimum number principle yields highly significant results for coalition formations in the period 1978–1986
    • …
    corecore