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General Nature (general + nature)
Selected AbstractsMiscibility in Blends of Isotactic/Syndiotactic Polystyrenes at Melt or Quenched Amorphous Solid StateMACROMOLECULAR MATERIALS & ENGINEERING, Issue 11 2006Shu Hsien Li Abstract Summary: Miscibility in amorphous phase and behavior in a crystalline phase of blends of two semicrystalline and isomeric polymers, isotactic polystyrene (iPS) and syndiotactic polystyrene (sPS), was probed. Optical and scanning electron microscopy results indicate no discernible heterogeneity in iPS/sPS blends in either melt state or rapidly quenched amorphous super-cooled state, while the Tg behavior of the quenched amorphous blends shows an intimately mixed state of two polymer chains. The crystal forms of the blends were further analyzed to provide additional evidence of miscibility in the amorphous domain. The sPS in the iPS/sPS blends upon melt crystallization was found to predominantly exist as the more stable , -form (rather than mixed , -form and , -form in neat sPS), which also suggests evidence of miscibility in the iPS/sPS blends. The melting behavior of semicrystalline sPS in the iPS/sPS mixtures was analyzed using the Flory-Huggins approach for estimation of interactions. By measuring the equilibrium melting point of the higher-melting sPS species in the sPS/iPS blends, a small negative value, for the interaction parameter (,,,,,0.11) was found. Further, by introducing a third polymer, poly(2,6-dimethyl- p -phenylene oxide) (PPO), a ternary iPS/sPS/PPO blend system was also proven miscible, which constituted a further test for stable phase miscibility in the iPS/sPS blend. General nature of miscibility in blends composed of two crystalline isomeric polymers is discussed. Issues in dealing with blends of polymers of the same chemical repeat unit but different tacticities were addressed. X-ray diffractograms for neat sPS and iPS/sPS blends, each having been isothermally crystallized at 245,°C for 4 h. [source] Planetary landscape systems: a limitless frontierEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2008Victor R. Baker Abstract If it is to be a complete science of landforms and landscapes, geomorphology is not appropriately limited geographically to the terrestrial portions of Earth's surface. Various systems of landforms and their generative processes are best understood in a full planetary context. Moreover, by extending its purview to include the nature of landscapes on Earth-like planets, geomorphological inquiry is not appropriately limited in its philosophical presumptions to the reductionist views that have so successfully guided much of physics. Holistic thinking, exemplified by some aspects of evolutionary biology, and a systems framework may prove to be particularly fruitful for understanding future extraterrestrial discoveries and the general nature of landforms and landscapes. Copyright © 2008 John Wiley & Sons, Ltd. [source] A stability criterion inherent in laws governing alluvial channel flowEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2002He Qing Huang Abstract The stability criterion of maximum flow efficiency (MFE) has previously been found inherent in typical alluvial channel flow relationships, and this study investigates the general nature of this criterion using a wider range of flow resistance and bedload transport formulae. For straight alluvial channels, in which the effect of sediment sorting is insignificant, our detailed mathematical analysis demonstrates that a flow efficiency factor , occurs generally as the ratio of sediment (bedload) discharge Qs to stream power , (,QS) in the form of . When , is maximized (i.e. Qs is maximized or , is minimized), maximally efficient straight channel geometries derived from most flow resistance and bedload transport formulae are found compatible with observed bankfull hydraulic geometry relations. This study provides support for the use of the criteria of MFE, maximum sediment transporting capacity and minimum stream power for understanding the operation of alluvial rivers, and also addresses limitations to the direct application of its findings. Copyright © 2002 John Wiley & Sons, Ltd. [source] The Bold and the Variable: Fish with High Heterozygosity Act Recklessly in the Vicinity of PredatorsETHOLOGY, Issue 1 2008Sampsa Vilhunen Variation in the innate behavioral response to predation threat is often assumed to reflect genetic differences among the prey individuals. To date, no published results, however, exist that would offer explanation for the origin of this behavioral variation within populations. Using microsatellites as markers, we estimated the genetic variability of juvenile brown trout (Salmo trutta) individuals whose behavior had been individually recorded in a trade-off situation where both predator chemical cues and food were present. Mean overall heterozygosity and the internal relatedness of fish associated significantly with their activity and foraging, so that the genetically more variable individuals showed more risk-prone behavior under predation risk. No association between genetic variability and behavior was found in trials where predator odors were not present. These results were consistent over the three study populations of brown trout with different backgrounds, suggesting that the phenomenon is of general nature in this species. Of the possible mechanisms suggested to enable the existence of the positive association between neutral microsatellite variation and fitness-related trait, the local effect hypothesis gained more support from our data than the general effect hypothesis. [source] Losing more than gaining from overall stable prices: the differential perception of increasing versus decreasing prices made the Euro look like a price boosterEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 5 2008Tobias Greitemeyer The present research examined whether price trend misperceptions can be explained by the differential perception of increasing versus decreasing prices. We expected price increases (losses to consumers) to be perceived as being more intense than price decreases (gains to consumers) of the same magnitude. This tendency, in turn, should be positively associated with how people perceive the overall price trend. To test this reasoning, participants in the first two studies were asked to compare German Mark (DM) and Euro prices. First, participants received a menu containing 21 dishes with DM prices, and their price trend expectations were assessed. Then, participants indicated for each dish to what extent the price had changed. Finally, participants' overall price trend judgments were assessed. In both studies, results indicate that price trend judgments were biased toward rising prices. In addition, price increases were perceived as rising more than price decreases of the same magnitude were perceived as falling. This tendency was positively associated with overall price trend judgments, even after controlling for expectations. Study 3 was to replicate these findings in a different domain to demonstrate the general nature and impact of the hypothesized effect. Copyright © 2007 John Wiley & Sons, Ltd. [source] Changes in spawning stock structure strengthen the link between climate and recruitment in a heavily fished cod (Gadus morhua) stockFISHERIES OCEANOGRAPHY, Issue 3 2006GEIR OTTERSEN Abstract Atlantic cod (Gadus morhua) is one of the commercially most important fish species in the North Atlantic and plays a central role in several ecosystems. Fishing pressure has been heavy over a prolonged period and the recent decades have shown dramatic decline in abundance of many stocks. The Arcto-Norwegian (or North-east Arctic) cod stock in the Barents Sea is now the largest stock of Atlantic cod. Recruitment to this stock has varied extensively during the last 60 yr. There is evidence for fluctuations in climate, particularly sea temperature, being a main cause for this variability, higher temperatures being favourable for survival throughout the critical early life stages. Our studies of time series present compelling evidence for a strengthening of the climate,cod recruitment link during the last decades. We suggest this is an effect of the age and length composition of the spawning stock having changed distinctly. The age of the average spawner has decreased by more than 3 yr from between 10 and 11 in the late 1940s to 7,8 in the 1990s, average length from just above 90 cm to around 80 cm. The number of age classes contributing to the spawning stock has also decreased, while the number of length groups present increased slightly. Significant decrease in age of spawners has frequently been described for other heavily fished stocks worldwide. We therefore find it likely that the proposed mechanism of increased influence of climate on recruitment through changes in the spawning stock age and size composition is of a general nature and might be found in other systems. [source] The role of the oceans in climateINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 10 2003G. R. Bigg Abstract The ocean is increasingly seen as a vital component of the climate system. It exchanges with the atmosphere large quantities of heat, water, gases, particles and momentum. It is an important part of the global redistribution of heat from tropics to polar regions keeping our planet habitable, particularly equatorward of about 30°. In this article we review recent work examining the role of the oceans in climate, focusing on research in the Third Assessment Report of the IPCC and later. We discuss the general nature of oceanic climate variability and the large role played by stochastic variability in the interaction of the atmosphere and ocean. We consider the growing evidence for biogeochemical interaction of climatic significance between ocean and atmosphere. Air,sea exchange of several radiatively important gases, in particular CO2, is a major mechanism for altering their atmospheric concentrations. Some more reactive gases, such as dimethyl sulphide, can alter cloud formation and hence albedo. Particulates containing iron and originating over land can alter ocean primary productivity and hence feedbacks to other biogeochemical exchanges. We show that not only the tropical Pacific Ocean basin can exhibit coupled ocean,atmosphere interaction, but also the tropical Atlantic and Indian Oceans. Longer lived interactions in the North Pacific and Southern Ocean (the circumpolar wave) are also reviewed. The role of the thermohaline circulation in long-term and abrupt climatic change is examined, with the freshwater budget of the ocean being a key factor for the degree, and longevity, of change. The potential for the Mediterranean outflow to contribute to abrupt change is raised. We end by examining the probability of thermohaline changes in a future of global warming. Copyright © 2003 Royal Meteorological Society [source] Across-sample Incomparability of R2s and Additional Evidence on Value Relevance Changes Over TimeJOURNAL OF BUSINESS FINANCE & ACCOUNTING, Issue 7-8 2007Zhaoyang GuArticle first published online: 9 OCT 200 Abstract:, Given the increasing popularity of across-sample R2 comparisons in accounting research, this paper illustrates why the regression R2s are incomparable across samples and the general nature of this problem. The regression residual dispersion with proper control for scale is proposed as the alternative measure of explanatory power for across-sample comparisons. In market-on-accounting variable regressions, this measure can be conveniently interpreted as the degree of accounting-based pricing errors and be used as a measure of value relevance of accounting information. As an application, the issue of over-time value relevance changes is re-visited. In contrast to prior mixed findings based on the R2 measure, a decline of value relevance since the early 1970s is robustly detected using the alternative measure. [source] Defining the linear portion of a sigmoid-shaped curve: bend pointsPHARMACEUTICAL STATISTICS: THE JOURNAL OF APPLIED STATISTICS IN THE PHARMACEUTICAL INDUSTRY, Issue 3 2003J. L. Sebaugh Abstract Formulae are provided that define the ,bend points', the beginning and end of the essentially linear dose,response region, for the four-parameter logistic model. The formulae are expressed in both response and dose units. The derivation of the formulae is shown in order to illustrate the general nature of the methodology. Examples are given that describe how the formulae may be used while planning and conducting bioassays. Copyright © 2003 John Wiley & Sons, Ltd. [source] Regional tourism and South-South economic cooperationTHE GEOGRAPHICAL JOURNAL, Issue 2 2001Krishna B. Ghimire Regional tourism within developing countries is a growing phenomenon. Yet this aspect has been largely neglected in social science research as well as tourism planning. This paper highlights the general nature, scale and economic significance of regional tourism in three leading regions in Asia, Africa and Latin America. The topic is especially timely as economic self-reliance and cooperation are increasingly reiterated in the context of the emergence of regional groupings. A key question addressed is whether regional tourism development represents any new and viable prospects for regional economic improvement and partnership, especially compared to international tourism centred on attracting visitors from industrialized countries. Based on a critical assessment of the experiences of three regional blocs (ASEAN , the Association of South-East Asian Nations; SADC , the Southern African Development Community; and Mercosur , a common market comprising Argentina, Brazil, Paraguay and Uruguay, with Chile being an associated member), the paper suggests that a basic appreciation of the prospects of regional tourism is not enough to produce perceptible benefits. Regional tourism development is occurring in a haphazard manner, with little attention to managing existing socio-economic inequalities and centre-periphery relations. The paper is based primarily on the review of secondary literature readily available to the author combined with a few documents obtained directly from different regional organizations or through Internet search. A small amount of material, especially concerning emerging tourism trends and outcomes, is drawn from a research project on national mass tourism in developing countries coordinated by the author at the United Nations Research Institute for Social Development, Geneva. [source] The Rich Tradition of Australian RealismAUSTRALIAN JOURNAL OF POLITICS AND HISTORY, Issue 3 2009Michael Wesley Australian International Relations (IR) developed as a discipline at the same time as its emergence in the rest of the Anglophone world. A deep reading of Australian writing on international relations since the 1920s reveals a distinctive tradition of IR scholarship, shaped very much by this country's international circumstances and the pragmatic culture of political inquiry that pervaded its universities and diplomatic institutions. Three characteristics frame the Australian Realist outlook. The first is experiential, a preoccupation with the particularities of Australia's international position , size, isolation, wealth, population, culture , and how these factors can help understand the ways in which Australia relates to the world beyond its shores. The second is systemic pessimism, a tendency to be apprehensive about broader global stability. The third is pragmatism, a predilection for understanding the essential attributes of the situation itself, rather than using the situation to inquire into the general nature of the international system. These characteristics have fostered sustained attention to three sets of issues: geography, demographics and race, and power differentials in Australian Realist scholarship. [source] | |||||||||||||