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New Theory (new + theory)
Selected AbstractsA NEW THEORY OF THE BUDGETARY PROCESSECONOMICS & POLITICS, Issue 1 2006SOUMAYA M. TOHAMY This paper offers an alternative to the view that budgetary decisions are incremental because they are complex, extensive, and conflicted. Our model interprets incrementalism as the result of a legislative political strategy in response to interest group politics and economic conditions. Accordingly, a legislator chooses between single-period budgeting or multiperiod budgeting, where single-period budgeting is associated with a greater chance of non-incremental budgeting outcomes. We use a statistical procedure developed by Dezhbakhsh et al. (2003) for identifying non-incremental outcomes to test the implications of the model. Results support the model's predictions: a higher discount rate and a persistently large deficit appear to cause departures from incremental budgeting; Democrats' control over the political process have a similar effect, while a higher inflation rate has an opposite effect. [source] A NEW THEORY OF THE INORGANIC WORLDPHILOSOPHICAL FORUM, Issue 1 2006PIERRE DUHEM First page of article [source] Does the "New" Immigration Require a "New" Theory of Intergenerational Integration?,INTERNATIONAL MIGRATION REVIEW, Issue 3 2004Hartmut Esser Starting from discussions on the validity of the classical assimilation concept, a general model for the explanation of different structural outcomes of interethnic relations is developed. The core of the model builds on the assumption that different outcomes are the often unintended and situation-logic results of (mis-)investments in and with ethnic and non-ethnic capital. Central initial conditions of the model are group size, social and cultural distances and the availability of social capital. The model specifies the mutual relations between these three constructs. Different variants of intergenerational integration of immigrants can thus be reconstructed as special cases of a general mechanism. [source] The Nursing Worklife Model: Extending and Refining a New TheoryJOURNAL OF NURSING MANAGEMENT, Issue 3 2007CCRN, MILISA MANOJLOVICH PhD Aims, We tested a modification of Leiter and Laschinger's Nursing Worklife Model by examining the impact of structural empowerment on professional work environment factors that lead to nursing job satisfaction. Background, The original model explains how five magnet hospital practice domains described by Lake (2002) interact to influence nurses' work lives by either contributing to or mitigating burnout. Methods, A non-experimental design was used. Five hundred randomly selected nurses in Michigan were surveyed (response rate 66%, n = 332). Instruments included the Conditions for Work Effectiveness Questionnaire-II, the Practice Environment Scale of the Nursing Work Index, and the Index of Work Satisfaction. Path analysis was used to test the model. Results, The final model fit the data well (,2 = 96.4, d.f. = 10, NFI: 0.90, CFI: 0.43, RMSEA: 0.18), supporting both hypotheses. Conclusions, The expanded Nursing Worklife Model demonstrates the role of empowerment in creating positive practice conditions that contribute to job satisfaction. [source] A glassy lowermost outer coreGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2009Vernon F. Cormier SUMMARY New theories for the viscosity of metallic melts at core pressures and temperatures, together with observations of translational modes of oscillation of Earth's solid inner core, suggest a rapid increase in the dynamic viscosity near the bottom of the liquid outer core. If the viscosity of the lowermost outer core (F region) is sufficiently high, it may be in a glassy state, characterized by a frequency dependent shear modulus and increased viscoselastic attenuation. In testing this hypothesis, the amplitudes of high-frequency PKiKP waves are found to be consistent with an upper bound to shear velocity in the lowermost outer core of 0.5 km s,1 at 1 Hz. The fit of a Maxwell rheology to the frequency dependent shear modulus constrained by seismic observations at both low and high-frequency favours a model of the F region as a 400-km-thick chemical boundary layer. This layer has both a higher density and higher viscosity than the bulk of the outer core, with a peak viscosity on the order of 109 Pa s or higher near the inner core boundary. If lateral variations in the F region are confirmed to correlate with lateral variations observed in the structure of the uppermost inner core, they may be used to map differences in the solidification process of the inner core and flow in the lowermost outer core. [source] Regulation of adult hippocampal neurogenesis , implications for novel theories of major depression1BIPOLAR DISORDERS, Issue 1 2002Gerd Kempermann Major depression, whose biological origins have been difficult to grasp for decades, might result from a disturbance in neuronal plasticity. New theories begin to consider a fundamental role of adult hippocampal neurogenesis in this loss of plasticity. Could depression and other mood disorders therefore be ,stem cell disorders'? In this review, the potential role of adult hippocampal neurogenesis and of neuronal stem or progenitor cells in depression is discussed with regard to those aspects that are brought up by recent research on how adult hippocampal neurogenesis is regulated. What is known about this regulation today are mosaic pieces and indicates that regulation is complex and is modulated on several levels. Accordingly, emphasis is here laid on those regulatory feedback mechanisms and interdependencies that could help to explain how the pathogenic progression from a hypothesized disruptive cause can occur and lead to the complex clinical picture in mood disorders. While the ,neurogenic theory' of depression remains highly speculative today, it might stimulate the generation of sophisticated working hypotheses, useful animal experiments and the first step towards new therapeutic approaches. [source] Geographic Concentration and Increasing ReturnsJOURNAL OF ECONOMIC SURVEYS, Issue 5 2003Paolo Surico Abstract., Economic activities are highly clustered. Why is geographic concentration becoming a predominant feature of industrialized economies? On the basis of the empirical models developed by the new theories of international trade, our answer is that increasing returns are the driving force of economic geography in the US as well as in Europe. In so doing, we review several econometric methods proposed in the literature to separate and to test alternative theoretical paradigms. [source] Americanist Archaeologies: 2008 in ReviewAMERICAN ANTHROPOLOGIST, Issue 2 2009B. Sunday Eiselt ABSTRACT A review of published literature, conference proceedings, and Internet sources pertaining to "Americanist archaeology" in 2008 reveals three major themes: conflict, catastrophe, and collaboration. Scholars debated the role of archaeology in planning for and executing military operations in the Middle East while maintaining a vigorous interest in structural and physical violence worldwide. Environmental archaeologists considered the effects of catastrophic events, including new theories over the demise of Clovis cultures. In addition, several major reports and regulations highlighted the complexities of indigenous relations and gender equity in the profession. Enhanced technologies, funding for global initiatives in human rights, economic and environmental sustainablility, and creative forms of engagement are reshaping "Americanist archaeology" as a democratic, anthropological, and relevant pursuit. [Keywords: archaeology, annual review, conflict, catastrophe, collaboration] [source] How Do Instructional-Design Practitioners Make Instructional-Strategy Decisions?PERFORMANCE IMPROVEMENT QUARTERLY, Issue 3 2004Trudy K. Christensen ABSTRACT Many theories have been proposed to help instructional designers make instructional-strategy decisions, yet it is not clear if these theories are actually used by ID practitioners. This study used a web-survey to examine the design strategies of 113 ID practitioners. The survey asked respondents to rate how frequently they used learning or ID theories as well as 10 other design strategies, to help make instructional-strategy decisions. Respondents were also asked how often they used different information sources to learn about new theories, trends, and strategies, and to respond to a set of contrasting statements depicting objectivist vs. construc-tivist assumptions. The results indicate that ID practitioners most often rely on interaction with others both as a means of making instructional-strategy decisions and of learning about new theories, trends, and strategies. Only fifty percent of the respondents said they regularly use theories when making instructional-strategy decisions, using other design strategies more frequently instead; and most practitioners are eclectic in their underlying philosophical assumptions. Based on these results, we discuss implications for training and ongoing support of instructional designers. [source] BOOKS, PRINTS, AND TRAVEL: READING IN THE GAPS OF THE ORIENTALIST ARCHIVEART HISTORY, Issue 3 2008ELISABETH A. FRASER From about 1780 a thriving publishing industry for travel accounts developed in France, but its rich visual component has not been closely analysed. Taking Auguste de Forbin's Voyage dans le Levant and Marie-Gabriel de Choiseul-Gouffier's Voyage pittoresque de la Grèce as paradigmatic examples, I reconsider illustrated travel books in light of new theories of reading generated by historians of the book. The multifarious nature of these books , juggling word and image, and coordinating the work of a large number of writers, researchers, artists and print-makers , provides a radically alternative model for interpreting travel representation in the age of expansion. [source] Taking post-development theory to the field: Issues in development research, Northern ThailandASIA PACIFIC VIEWPOINT, Issue 3 2008Katharine McKinnon Abstract Emerging post-development literatures consider how post-structural and post-colonial critiques of development could form the basis for new kinds of development practices. Much of the search for such post-development possibilities draws on new theories of discourse. This paper considers the challenges of bringing together empirical research and the experience of doing development with the often ethereal and deeply speculative work of discourse theorists. I reflect on the course taken by my own research in Northern Thailand, and discuss the possibilities that can emerge as theory confronts empirics, and conceptual frameworks are transformed through the daily politics of fieldwork. [source] Cosmology: a matter of all and nothingASTRONOMY & GEOPHYSICS, Issue 4 2002John D Barrow John D Barrow gave the Gerald Whitrow Lecture for 2002. He reviews modern ideas about the Big Bang and the constants of Nature. Abstract The modern picture of the expanding Big Bang universe is described. Implications of the expansion for the evolution of life are highlighted, together with the new features contributed by the inflationary universe theory. Observational tests of inflation are described along with some of the possibilities introduced by new theories of strings and quantum gravity. These theories allow the numbers of dimensions of space and of time to be larger than the three and one we experience and permit the observed "constants" of Nature to vary slowly in time. We describe recent astronomical evidence that is consistent with small variations of the fine-structure constant and discuss some of its far-reaching implications. [source] The genome-centric concept: resynthesis of evolutionary theoryBIOESSAYS, Issue 5 2009Henry H. Q. Heng Abstract Modern biology has been heavily influenced by the gene-centric concept. Paradoxically, this very concept , on which bioresearch is based , is challenged by the success of gene-based research in terms of explaining evolutionary theory. To overcome this major roadblock, it is essential to establish new theories, to not only solve the key puzzles presented by the gene-centric concept, but also to provide a conceptual framework that allows the field to grow. This paper discusses a number of paradoxes and illustrates how they can be addressed by the genome-centric concept in order to further resynthesize evolutionary theory. In particular, methodological breakthroughs that analyze genome evolution are discussed. The multiple interactions among different levels of a complex system provide the key to understanding the relationship between self-organization and natural selection. Darwinian natural selection applies to the biological level due to its unique genetic and heterogeneous features, but does not simply or directly apply to either the lower non-living level or higher intellectual society level. At the complex bio-system level, the genome context (the entire package of genes and their genomic physical relationship or genomic topology), not the individual genes, defines the system and serves as the principle selection platform for evolution. [source] The Anticipated Utility of Zoos for Developing Moral Concern in ChildrenCURATOR THE MUSEUM JOURNAL, Issue 4 2009John Fraser It proposes a new theory regarding the psychological value of such experiences for the development of identity. The study used a constructivist grounded theory approach to explore parenting perspectives on the value of zoo visits undertaken by eight families from three adjacent inner-city neighborhoods in a major American city. The results suggest that parents use zoo visits as tools for promoting family values. These parents felt that experiences with live animals were necessary to encourage holistic empathy, to extend children's sense of justice to include natural systems, and to model the importance of family relationships. The author concludes that parents find zoos useful as a tool for helping their children to develop skills with altruism, to transfer environmental values, to elevate children's self-esteem, and to inculcate social norms that they believe will aid in their children's social success in the future. [source] User-Centred Time Geography for Location-Based ServicesGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 4 2004Martin Raubal Abstract Location-based services assist people in their decision-making during the performance of tasks in space. They do not consider the user's individual preferences, time constraints and possible subtasks to be performed. In order to account for these important aspects, a user-centred spatio-temporal theory of location-based services is required. We propose such a theory by combining classical time geography with an extended theory of affordances. It assumes that affordances belong to three realms: physical, social-institutional, and mental. In addition to covering the capability, coupling and authority constraints from time geography, this allows for a user-centred perspective because affordances describe action possibilities with regard to a specific person. Furthermore, the integration of mental affordances offers the possibility to account for cognitive time constraints due to the duration of decision-making processes. This new theory for location-based services is closer to the individual user and more plausible with respect to their daily lives. A business traveller scenario is used as a case study to demonstrate this. [source] Bond rolling resistance and its effect on yielding of bonded granulates by DEM analysesINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 8 2006M. J. Jiang Abstract A discrete element modelling of bonded granulates and investigation on the bond effect on their behaviour are very important to geomechanics. This paper presents a two-dimensional (2-D) discrete element theory for bonded granulates with bond rolling resistance and provides a numerical investigation into the effect of bond rolling resistance on the yielding of bonded granulates. The model consists of mechanical contact models and equations governing the motion of bonded particles. The key point of the theory is that the assumption in the original bond contact model previously proposed by the authors (55th CSCE-ASCE Conference, Hamilton, Ont., Canada, 2002; 313,320; J. Eng. Mech. (ASCE) 2005; 131(11):1209,1213) that bonded particles are in contact at discrete points, is here replaced by a more reliable assumption that bonded particles are in contact over a width. By making the idealization that the bond contact width is continuously distributed with the normal/tangential basic elements (BE) (each BE is composed of spring, dashpot, bond, slider or divider), we establish a bond rolling contact model together with bond normal/tangential contact models, and also relate the governing equations to local equilibrium. Only one physical parameter , needs to be introduced in the theory in comparison to the original bond discrete element model. The model has been implemented into a 2-D distinct element method code, NS2D. Using the NS2D, a total of 86 1-D, constant stress ratio, and biaxial compressions tests have been carried out on the bonded granular samples of different densities, bonding strengths and rolling resistances. The numerical results show that: (i) the new theory predicts a larger internal friction angle, a larger yielding stress, more brittle behaviour and larger final broken contact ratio than the original bond model; (ii) the yielding stress increases nonlinearly with the increasing value of ,, and (iii) the first-yield curve (initiation of bond breakage), which define a zone of none bond breakage and which shape and size are affected by the material density, is amplified by the bond rolling resistance in analogous to that predicted by the original bond model. Copyright © 2006 John Wiley & Sons, Ltd. [source] Could "Acculturation" Effects Be Explained by Latent Health Disadvantages Among Mexican Immigrants?INTERNATIONAL MIGRATION REVIEW, Issue 3 2009Brian K. Finch This paper tests portions of a new theory of immigrant health by focusing exclusively on latent biomarkers of future health risks. Using data from the National Health and Nutrition Examination Survey III, 1988,1994 , we uncover the typically observed immigrant health advantage among recent immigrants that diminishes among long-term immigrants. In addition, we observe worse health among U.S.-born Mexican Americans relative to non-Hispanic Whites. Finally, although our theory suggests that recent immigrants may have latent health risks due to disadvantaged childhood experiences, we do not find evidence in support of this theory. [source] Measurement of body size and abundance in tests of macroecological and food web theoryJOURNAL OF ANIMAL ECOLOGY, Issue 1 2007SIMON JENNINGS Summary 1Mean body mass (W) and mean numerical (N) or biomass (B) abundance are frequently used as variables to describe populations and species in macroecological and food web studies. 2We investigate how the use of mean W and mean N or B, rather than other measures of W and/or accounting for the properties of all individuals, can affect the outcome of tests of macroecological and food web theory. 3Theoretical and empirical analyses demonstrate that mean W, W at maximum biomass (Wmb), W when energy requirements are greatest (Wme) and the W when a species uses the greatest proportion of the energy available to all species in a W class (Wmpe) are not consistently related. 4For a population at equilibrium, relationships between mean W and Wme depend on the slope b of the relationship between trophic level and W. For marine fishes, data show that b varies widely among species and thus mean W is an unreliable indicator of the role of a species in the food web. 5Two different approaches, ,cross-species' and ,all individuals' have been used to estimate slopes of abundance,body mass relationships and to test the energetic equivalence hypothesis and related theory. The approaches, based on relationships between (1) log10 mean W and log10 mean N or B, and (2) log10 W and log10 N or B of all individuals binned into log10 W classes (size spectra), give different slopes and confidence intervals with the same data. 6Our results show that the ,all individuals' approach has the potential to provide more powerful tests of the energetic equivalence hypothesis and role of energy availability in determining slopes, but new theory and empirical analysis are needed to explain distributions of species relative abundance at W. 7Biases introduced when working with mean W in macroecological and food web studies are greatest when species have indeterminate growth, when relationships between W and trophic level are strong and when the range of species'W is narrow. [source] A New Era of Minimal Effects?JOURNAL OF COMMUNICATION, Issue 1 2010A Response to Bennett, Iyengar This article takes up Bennett and Iyengar's (2008) call for debate about the future of political communication effects research. We outline 4 key criticisms. First, Bennett and Iyengar are too quick to dismiss the importance of attitude reinforcement, long recognized as an important type of political media influence. Second, the authors take too narrow a view of the sources of political information, remaining fixated on news. Third, they offer an incomplete portrayal of selective exposure, exaggerating the extent to which individuals avoid attitude-discrepant information. Finally, they lean toward determinism when describing the role technologies play in shaping our political environment. In addition, we challenge Bennett and Iyengar's assertion that only brand new theory can serve to help researchers understand today's political communication landscape. We argue that existing tools, notably the Elaboration Likelihood Model (ELM), retain much utility for examining political media effects. Contrary to Bennett and Iyengar's claims, the ELM suggests that the contemporary political information environment does not necessarily lead to minimal effects. [source] ACCI Memorial Paper: The Scholarly Legacy of E. Scott MaynesJOURNAL OF CONSUMER AFFAIRS, Issue 1 2010LOREN V. GEISTFELD This paper honors E. Scott Maynes, who died on June 24, 2007 and had been a professor emeritus in the Department of Policy Analysis and Management at Cornell University. The paper describes Scott's scholarly legacy in research, highlighting four areas: survey research methods, research using data from Surveys of Consumer Finances, Scott's studies of local consumer markets, and two significant books Scott Maynes authored. The author of this memorial paper concludes that Scott's scholarly legacy is neither a new theory nor a new statistical technique but the importance of vision, passion, perseverance, commitment, and creativity for the applied social science researcher. [source] The role of ring-ring equilibria in thermodynamically controlled polycondensationsMACROMOLECULAR SYMPOSIA, Issue 1 2003Hans R. Kricheldorf Abstract Thermodynamically controlled polycondensations (TCPs) involve rapid equilibration reactions, such as transesterification, transamidation, etc. An important component of these equilibration reactions is the reversible formation of cyclic oligomers and polymers by "back-biting". Therefore, TCPs were described in the previous literature in terms of ring-chain equilibria. The present study presents a complementary theory saying that ring-chain equilibria automatically include ring-ring equilibria which gain in importance with higher conversions because the molar ratio of rings versus linear chains rapidly increases. At 100% conversion, all reaction products will be cycles and the ring-ring equilibria limit the chain growth. Several polycondensations cited from the literature are discussed in the light of the new theory. [source] Return Dynamics when Persistence is UnobservableMATHEMATICAL FINANCE, Issue 4 2001Timothy C. Johnson This paper proposes a new theory of the sources of time-varying second (and higher) moments in financial time series. The key idea is that fully rational agents must infer the stochastic degree of persistence of fundamental shocks. Endogenous changes in their uncertainty determine the evolution of conditional moments of returns. The model accounts for the principal observed features of volatility dynamics and implies some new ones. Most strikingly, it implies a relationship between ex post trends, or momentum, and changes in volatility. [source] Superperformance: A new theory for optimizationPERFORMANCE IMPROVEMENT, Issue 5 2008Dave Guerra This article examines a new framework for managing and leading that provides an astonishingly simple path forward through today's complex world of work, introducing a new paradigm for optimizing both organizations and individuals. Superperformance emerges when process and passion merge to become one. The discovery of superperformance points to the incontrovertible need for a new management science. [source] A Critical Appraisal of Vitiligo Etiologic Theories.PIGMENT CELL & MELANOMA RESEARCH, Issue 4 2003Is Melanocyte Loss a Melanocytorrhagy? Common generalized vitiligo is an acquired depigmenting disorder characterized by a chronic and progressive loss of melanocytes from the epidermis and follicular reservoir. However, the mechanism of melanocyte disappearance has never been clearly understood, and the intervention of cellular and humoral autoimmune phenomena as primary events remains unproven. In this review, is discussed the data supporting the major theories of vitiligo, namely melanocyte destruction (autoimmune, neural and impaired redox status) and melanocyte inhibition or defective adhesion. Based on recent morphologic findings in vivo supporting a chronic detachment and transepidermal loss of melanocytes in common generalized vitiligo, a new theory is suggested proposing melanocytorrhagy as the primary defect underlying melanocyte loss, integrating most of the possible triggering/precipitating/enhancing effects of other known factors. [source] VIII,Cognitive Expressivism, Faultless Disagreement, and Absolute but Non -Objective TruthPROCEEDINGS OF THE ARISTOTELIAN SOCIETY (HARDBACK), Issue 2pt2 2010Stephen Barker I offer a new theory of faultless disagreement, according to which truth is absolute (non-relative) but can still be non-objective. What's relative is truth-aptness: a sentence like ,Vegemite is tasty' (V) can be truth-accessible and bivalent in one context but not in another. Within a context in which V fails to be bivalent, we can affirm that there is no issue of truth or falsity about V, still disputants, affirming and denying V, were not at fault, since, in their context of assertion V was bivalent. This theory requires a theory of assertion that is a form of cognitive expressivism. [source] Consumer vulnerability to scams, swindles, and fraud: A new theory of visceral influences on persuasionPSYCHOLOGY & MARKETING, Issue 7 2001Jeff Langenderfer Scams exact a huge toll on consumers and society at large, with annual costs in the United States alone exceeding $100 billion. The global proliferation of the Internet has enabled con artists to export their craft to a rapidly expanding market and reach previously untapped consumers. In spite of the prevalence of scams around the world, there has been virtually no academic attention devoted to understanding the factors that might account for why individuals differ in their scamming vulnerability. Building on the background of elder consumer disadvantage and informed by the authors' own survey of expert opinion, this article presents a tentative theory of scamming vulnerability. The proposed theory incorporates the effects of visceral influences on consumer response to scam offers and hypothesizes a role for various moderating factors such as self-control, gullibility, susceptibility to interpersonal influence, and scam knowledge. Theoretical propositions are provided for future empirical investigation. © 2001 John Wiley & Sons, Inc. [source] Understanding and treating African immigrant families: new questions and strategies,PSYCHOTHERAPY AND POLITICS INTERNATIONAL, Issue 2 2009Augustine Nwoye Abstract In her very important article published in Family Process, Falicov (2007) recognized the need for expanding the dominant Western notions of the family, community and culture and to adopt new theory and treatment considerations for working with transnational immigrants. Unfortunately, her discussion, despite its originality and significance, was largely limited to addressing the problems and challenges faced by well-established immigrants, who present with symptoms precipitated by relational stresses and difficult choices. This article draws attention to another category of immigrants , the Green-Carded African Immigrants in Europe and North America, whose special concerns and problems were left unaccounted for in Falicov's contribution. It aims to broaden and extend the current Western frameworks for understanding and treating the psychological needs and challenges of transnational immigrants. In this regard, it is argued that in addition to such currently existing Western models for working with established immigrants in Europe and North America (Falicov, 2003, 2007), successful work with Green-Carded African immigrants must begin by taking into account their journey motif; their narratives of hope and significance and failed constructions, and the cosmopolitan perspective of these immigrants. The article clarifies these issues, introducing new concepts and strategies for working with African immigrant families in Europe and North America. Copyright © 2009 John Wiely & Sons, Ltd. [source] BUREAUCRACIES REMEMBER, POST-BUREAUCRATIC ORGANIZATIONS FORGET?PUBLIC ADMINISTRATION, Issue 2 2009CHRISTOPHER POLLITT The paper examines the hypothesis that post-bureaucratic forms of organization perform less well than traditional bureaucracies with respect both to organizational memory and learning from experience. First, the paper discusses the meanings of the main terms and concepts to be used in the argument, and delimits its domain. Second, it identifies a series of mechanisms that are likely to bring about memory loss. Third, it examines the empirical literature in search of evidence to confirm or disconfirm the existence and effects of these mechanisms. Fourth, it reflects on its own limitations. Finally, it sets out some broad conclusions concerning the state of organizational memories in the public sector. The aim is to develop new theory, identify relevant generative mechanisms, set this model alongside such evidence as is available, and suggest lines for further research. The new men of the Empire are the ones who believe in fresh starts, new chapters, clean pages; I struggle on with the old story, hoping that, before it is finished, it will reveal to me why it was that I thought it worth the trouble. (J. M. Coetzee, Waiting for the Barbarians, 1980, p. 26) [source] Multiphase flow at the edge of a steam chamberTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010Jyotsna Sharma Abstract The use of steam-assisted gravity drainage (SAGD) to recover bitumen from Athabasca deposits in Alberta has been growing. Butler [Butler, J. Can. Pet. Tech. 1985;24:42,51] derived a simple theory to calculate the production rate of oil during SAGD in an ideal reservoir. This simple and useful theory made several assumptions about the properties of the reservoir and operating conditions of the process. The theory also assumed that the highest mobility oil is at the edge of the steam chamber and that the oil phase velocity is highest at the chamber edge and reduces with distance into the oil sand. This research examines flow conditions at the edge of the steam chamber. Specifically, a new theory is derived that takes into account the impact of oil saturation and relative permeability on the oil mobility profile at the edge of a steam chamber. It is shown that the flow behaviour at the edge of a steam chamber is more complex and is not fully represented by Butler's theory. Contrary to Butler's theory, the oil mobility has its maximum some distance away from the edge of the steam chamber. The results reveal that the higher the thermal diffusivity of the oil sand, the deeper the location where the oil phase velocity is maximum. The developed model has been validated against published experimental and field data. On a enregistré une forte augmentation de l'utilisation du procédé de drainage gravitaire en présence de vapeur (technique SAGD) pour récupérer le bitume naturel des gisements de l'Athabasca, Alberta. Butler (1985) a mis en place une théorie simple pour calculer le taux de production de pétrole durant l'utilisation de la technique SAGD dans un réservoir idéal. Cette théorie simple et utile fait plusieurs hypothèses sur les propriétés du réservoir et les conditions opératoires du processus. La théorie suppose également que le pétrole ayant la mobilité la plus élevée se trouve au bord de la chambre de vapeur et que la vélocité de la phase huileuse est à son niveau le plus élevé au niveau du bord de la chambre et qu'elle diminue ensuite avec la distance à l'intérieur des sables bitumineux. Ce travail de recherche examine les conditions d'écoulement au niveau des bords de la chambre de vapeur. De façon plus spécifique, une nouvelle théorie est mise en place en tenant compte de l'impact de la saturation en pétrole et de la perméabilité relative sur le profil de mobilité du pétrole au niveau des bords de la chambre de vapeur. On montre que le comportement de l'écoulement au niveau des bords d'une chambre de vapeur est plus complexe que prévu et qu'il n'est totalement représenté par la théorie de Butler. Contrairement à la théorie de Butler, la mobilité du pétrole présente son maximum à une certaine distance à l'écart des bords de la chambre de vapeur. Les résultats révèlent que plus la diffusivité thermique des sables bitumeux est élevée, plus le lieu de vélocité maximale de la phase huileuse est profond. Le modèle développé a été validé contre des données expérimentales publiées et des données obtenues sur le terrain. [source] The geography of tyranny and despair: development indicators and the hypothesis of genetic inevitability of national inequalityTHE GEOGRAPHICAL JOURNAL, Issue 3 2008STEPHEN MORSE Development geography has long sought to understand why inequalities exist and the best ways to address them. Dependency theory sets out an historical rationale for under development based on colonialism and a legacy of developed core and under-developed periphery. Race is relevant in this theory only insofar that Europeans are white and the places they colonised were occupied by people with darker skin colour. There are no innate biological reasons why it happened in that order. However, a new theory for national inequalities proposed by Lynn and Vanhanen in a series of publications makes the case that poorer countries have that status because of a poorer genetic stock rather than an accident of history. They argue that IQ has a genetic basis and IQ is linked to ability. Thus races with a poorer IQ have less ability, and thus national IQ can be positively correlated with performance as measured by an indicator like GDP/capita. Their thesis is one of despair, as little can be done to improve genetic stock significantly other than a programme of eugenics. This paper summarises and critiques the Lynn and Vanhanen hypothesis and the assumptions upon which it is based, and uses this analysis to show how a human desire to simplify in order to manage can be dangerous in development geography. While the attention may naturally be focused on the ,national IQ' variables as a proxy measure of ,innate ability', the assumption of GDP per capita as an indicator of ,success' and ,achievement' is far more readily accepted without criticism. The paper makes the case that the current vogue for indicators, indices and cause,effect can be tyrannical. [source] | |||||||||||||||||||||||||||||||||||||||||||