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Offers Explanations (offer + explanation)
Selected AbstractsThe mid-season crash in aphid populations: why and how does it occur?ECOLOGICAL ENTOMOLOGY, Issue 4 2004A. J. Karley Abstract., 1. Aphid populations on agricultural crops in temperature regions collapse over a few days from peak numbers to local extinction soon after mid-summer (e.g. mid-July in the U.K.). The populations recover 6,8 weeks later. There is anecdotal or incidental evidence of an equivalent mid-season population crash of aphids on grasses and forbs in natural vegetation. 2. The ecological factors causing the mid-season population crash of aphids include a decline in plant nutritional quality and increased natural enemy pressure as the season progresses. Extreme weather events, e.g. severe rainstorms, can precipitate the crash but weather conditions are not a consistent contributory factor. 3. The population processes underlying the crash comprise enhanced emigration, especially by alate (winged) aphids, depressed performance resulting in reduced birth rates, and elevated mortality caused by natural enemies. 4. Mathematical models, previously applied to aphid populations on agricultural crops, have great potential for studies of aphid dynamics in natural vegetation. In particular, they can help identify the contribution of various ecological factors to the timing of the population crash and offer explanations for how slow changes in population processes can result in a rapid collapse of aphid populations. [source] Money with a Mean Streak?INTERNATIONAL STUDIES QUARTERLY, Issue 2 2001Foreign Economic Penetration, Government Respect for Human Rights in Developing Countries This study examines the relationship between foreign economic capital and the level of government respect for two types of human rights in developing countries. Two opposing schools of thought offer explanations as to what this relationship might be like. According to the liberal neoclassical school, the acceptance of liberal economic doctrine will provide positive political benefits to developing countries. The "dependency" school, on the other hand, argues that because ties between core and periphery elites give governments in developing nations an incentive to repress, human rights conditions will worsen as foreign economic penetration increases. The results of previous empirical queries into this matter have been mixed. In contrast to most studies, we focus on a broader measure of foreign economic capital, including foreign direct investment, portfolio investment, debt, and official development assistance. Using ordered logit analysis on a cross-national sample of forty-three developing countries from 1981 to 1995, we discover systematic evidence of an association between foreign economic penetration and government respect for two types of human rights, physical integrity rights and political rights and civil liberties. Of particular interest is the finding that both foreign direct investment and portfolio investment are reliably associated with increased government respect for human rights. [source] Natural gas prices and the gas storage report: Public news and volatility in energy futures marketsTHE JOURNAL OF FUTURES MARKETS, Issue 3 2004Scott C. Linn This study examines the short-term volatility of natural gas prices through an examination of the intraday prices of the nearby natural gas futures contract traded on the New York Mercantile Exchange. The influence on volatility of what many regard as a key element of the information set influencing the natural gas market is investigated. Specifically, we examine the impact on natural gas futures price volatility of the Weekly American Gas Storage Survey report compiled and issued by the American Gas Association during the period January 1, 1999 through May 3, 2002 and the subsequent weekly report compiled and issued by the U.S. Energy Information Administration after May 6, 2002. We find that the weekly gas storage report announcement was responsible for considerable volatility at the time of its release and that volatility up to 30 minutes following the announcement was also higher than normal. Aside from these results, we document pronounced price volatility in this market both at the beginning of the day and at the end of the day and offer explanations for such behavior. Our results are robust to the manner in which the mean percentage change in the futures price is estimated and to correlation of these changes both within the day and across days. © 2004 Wiley Periodicals, Inc. Jrl Fut Mark 24:283,313, 2004 [source] Gastrointestinal, selective airways and urinary bladder relaxant effects of Hyoscyamus niger are mediated through dual blockade of muscarinic receptors and Ca2+ channelsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 1 2008Anwarul Hassan Gilani Abstract This study describes the spasmolytic, antidiarrhoeal, antisecretory, bronchodilatory and urinary bladder relaxant properties of Hyoscyamus niger to rationalize some of its medicinal uses. The crude extract of H. niger seeds (Hn.Cr) caused a complete concentration-dependent relaxation of spontaneous contractions of rabbit jejunum, similar to that caused by verapamil, whereas atropine produced partial inhibition. Hn.Cr inhibited contractions induced by carbachol (1 ,m) and K+ (80 mm) in a pattern similar to that of dicyclomine, but different from verapamil and atropine. Hn.Cr shifted the Ca2+ concentration,response curves to the right, similar to that caused by verapamil and dicyclomine, suggesting a Ca2+ channel-blocking mechanism in addition to an anticholinergic effect. In the guinea-pig ileum, Hn.Cr produced a rightward parallel shift of the acetylcholine curves, followed by a non-parallel shift with suppression of the maximum response at a higher concentration, similar to that caused by dicyclomine, but different from that of verapamil and atropine. Hn.Cr exhibited antidiarrhoeal and antisecretory effects against castor oil-induced diarrhoea and intestinal fluid accumulation in mice. In guinea-pig trachea and rabbit urinary bladder tissues, Hn.Cr caused relaxation of carbachol (1 ,m) and K+ (80 mm) induced contractions at around 10 and 25 times lower concentrations than in gut, respectively, and shifted carbachol curves to the right. Only the organic fractions of the extract had a Ca2+ antagonist effect, whereas both organic and aqueous fractions had anticholinergic effect. A constituent, ,-sitosterol exhibited Ca2+ channel-blocking action. These results suggest that the antispasmodic effect of H. niger is mediated through a combination of anticholinergic and Ca2+ antagonist mechanisms. The relaxant effects of Hn.Cr occur at much lower concentrations in the trachea and bladder. This study offers explanations for the medicinal use of H. niger in treating gastrointestinal and respiratory disorders and bladder hyperactivity. [source] Going Against the Historical Grain: Perspectives on Gendered Occupational Identity and Resistance to the Breakdown of Occupational Segregation in Two Manufacturing FirmsGENDER, WORK & ORGANISATION, Issue 3 2002Anne-marie Greene This article discusses a process of restructuring of working practices within two manufacturing firms with respect to its implications for gendered occupational segregation. A contextualized, historically situated analysis is presented, which is cast within debates on the nature of gendered occupational identity, equality initiatives and arenas of power and influence for women and men, within what were traditionally male-dominated organizational contexts. Such an analysis serves to highlight the significance of the new restructuring in sweeping away 150 years of practice and embedded ,ways of doing things' and offers explanations for the actions of contemporary men and women in opposing what were seen by management and the trade union as emancipatory changes. [source] 1. NARRATIVE FORM AND HISTORICAL SENSATION: ON SAUL FRIEDLÄNDER'S THE YEARS OF EXTERMINATION,HISTORY AND THEORY, Issue 3 2009ALON CONFINO ABSTRACT Saul Friedländer's magnum opus, The Years of Extermination, has been received worldwide as an exemplary work of history. Yet it was written by a historian who in the last two decades has strenuously asserted the limits of Holocaust representation. At the center of this essay is a problem of historical writing: how to write a historical narrative of the Holocaust that both offers explanations of the unfolding events and also suggests that the most powerful sensation about those events, at the time and since, is that they are beyond words. I explore Friedländer's crafting of such a narrative by considering, first, the role of his attempt in The Years of Extermination to explain the Holocaust and, second, the narrative form of the book. The book is best seen, I argue, not primarily as a work of explanation but as a vast narrative that places an explanation of the Holocaust within a specific form of describing that goes beyond the boundaries of the historical discipline as it is usually practiced. This form of describing goes beyond the almost positivist attachment to facts that dominates current Holocaust historiography. By using Jewish individual testimonies that are interspersed in the chronological history of the extermination, Friedländer creates a narrative based on ruptures and breaks, devices we associate with works of fiction, and that historians do not usually use. The result is an arresting narrative, which I interpret by using Johan Huizinga's notion of historical sensation. Friedländer sees this narrative form as specific to the Holocaust. I view this commingling of irreducible reality and the possibility of art as a required sensibility that belongs to all historical understanding. And in this respect, The Years of Extermination only lays bare more clearly in the case of the Holocaust what is an essential element in all historical reconstruction. [source] Composite Particles of Novozyme,435 and Silicone: Advancing Technical Applicability of Macroporous Enzyme CarriersCHEMCATCHEM, Issue 4 2009Abstract The mechanical and leaching stability of enzymes adsorbed on macroporous carriers is an important issue for the technical applicability of such biocatalysts. Both can considerably benefit from the deposition of silicone coating on the carrier surface. The coating of the immobilized lipase Novozyme,435 (NZ435), as a model enzyme preparation, with different silicone loadings was studied in detail by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as well as by energy-dispersive X-ray spectroscopy (EDX) and BET isotherms, and offers explanations and prerequisites for its stabilizing effects. The deposition of silicone on the poly(methyl methacrylate) (PMMA) carrier was found to form an interpenetrating network composite rather than the anticipated core-shell structure. The silicone precursors homogeneously wet the carrier surface including all inner pores and gradually fill the complete carrier. In parallel, the surface area of NZ435 decreases from an initial value of 89,m2g,1to 0.2,m2g,1after silicone loading. A visible layer of silicone on the outer surface of the carrier was only observed at a silicone concentration of 54,%,w/w and more. Maximum leaching stability corresponds to the formation of this layer. The mechanical stability increases with the amount of deposited silicone. It can be expected that stabilization against leaching and/or mechanical stress by formation of silicone composites can easily be transferred to a whole range of alternative biocatalytic systems. This should considerably advance their general technical applicability and overall implementation of biocatalysts in chemical synthesis. [source] | ||||||||||