Alternative Set (alternative + set)

Distribution by Scientific Domains


Selected Abstracts


Conflict and identity shape shifting in an online financial community

INFORMATION SYSTEMS JOURNAL, Issue 5 2009
John Campbell
Abstract., This paper challenges traditional explorations of online communities that have relied upon assumptions of trust and social cohesion. In the analysis presented here, conflict becomes more than just dysfunctional communication and provides an alternative set of unifying principles and rationales for understanding social interaction and identity shape shifting within an online community. A model is advanced that describes the systematic techniques of hostility and aggression in technologically enabled communities that take the form of contemporary tribalism. It is argued that this tribe-like conflict embodies important rituals essential for maintaining and defining the contradictory social roles sometimes found in online environments. This research offers a critical interpretive perspective that focuses on the link between identity shape shifting behaviours and the power relations within an online financial community. The analysis reveals how conflict between positions of power can help to align the values and ideals of an online community. With this study we seek to motivate a re-examination of the design and governance of online communities. [source]


On an initial-boundary value problem for a wide-angle parabolic equation in a waveguide with a variable bottom

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 12 2009
V. A. Dougalis
Abstract We consider the third-order Claerbout-type wide-angle parabolic equation (PE) of underwater acoustics in a cylindrically symmetric medium consisting of water over a soft bottom B of range-dependent topography. There is strong indication that the initial-boundary value problem for this equation with just a homogeneous Dirichlet boundary condition posed on B may not be well-posed, for example when B is downsloping. We impose, in addition to the above, another homogeneous, second-order boundary condition, derived by assuming that the standard (narrow-angle) PE holds on B, and establish a priori H2 estimates for the solution of the resulting initial-boundary value problem for any bottom topography. After a change of the depth variable that makes B horizontal, we discretize the transformed problem by a second-order accurate finite difference scheme and show, in the case of upsloping and downsloping wedge-type domains, that the new model gives stable and accurate results. We also present an alternative set of boundary conditions that make the problem exactly energy conserving; one of these conditions may be viewed as a generalization of the Abrahamsson,Kreiss boundary condition in the wide-angle case. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Degradation of the auxin response factor ARF1

THE PLANT JOURNAL, Issue 1 2008
Jemma Salmon
Summary Auxin-mediated gene expression is largely controlled through a family of DNA-binding proteins known as auxin response factors (ARF). Previous studies on the role of proteolytic regulation in auxin signaling have focused on degradation of their interacting partner, the Aux/IAA proteins. Aux/IAA family members with domain II sequences are rapidly degraded, show auxin-enhanced degradation rates, and interact with the related F-box proteins TIR1 and AFB1-3, which indicates that they are ubiquitylated by a CUL1-dependent E3 ligase. To date, limited data have been generated regarding degradation of ARFs. Here, we focus on the degradation rate of one ARF family member, Arabidopsis thaliana ARF1, and find that the half-lives of N-terminally HA-tagged ARF1 and C-terminally luciferase-tagged ARF1 are both approximately 3,4 h. This half-life appears to be conferred by a component of the middle region (MR), and degradation of the luciferase fusion with the MR is more rapid when the fusion includes an additional nuclear localization signal. ARF1 degradation is proteasome-dependent and rates are not altered in a CUL1 mutant background, suggesting that this ARF is targeted for proteasomal degradation via an alternative set of machinery to that used for Aux/IAA degradation. Consistent with this, exogenous indole acetic acid does not affect the degradation of ARF1. Given increasing evidence that the relative ratio of Aux/IAAs to ARFs rather than the absolute quantity within the cell appears to be the mode through which auxin signaling is modulated, this half-life is likely to be biologically relevant. [source]


American Economic Relations with Asia

ASIAN ECONOMIC POLICY REVIEW, Issue 2 2009
Marcus NOLAND
F5; F02; F13; F33 The USA and Asia have an enormous stake in each others' continuing prosperity. This outcome is linked to the preservation of the open international economic order, which in turn faces challenges at both the interstate diplomatic level and at the domestic political level. The global financial crisis is probably the worst since the Great Depression and the domestic politics makes it increasingly difficult to formulate a constructive trade policy. In the absence of adequate reform at the global level, the alternative could be further fragmentation into competing regional blocs. Asia holds the key, combining both dissatisfaction with existing global arrangements with the resources to reconstitute, at least at the regional level, an alternative set of institutions and practices. How Asia responds, acting to strengthen reformed global institutions or undermine them in favor of regional alternatives, will partly depend on the policies of the dominant global power, the USA. [source]


A Nationwide Assessment of the Biodiversity Value of Uganda's Important Bird Areas Network

CONSERVATION BIOLOGY, Issue 1 2006
HERBERT TUSHABE
AIAs; complementariedad; congruencia trans-taxón; selección de sitios de conservación Abstract:,BirdLife International's Important Bird Areas (IBA) program is the most developed global system for identifying sites of conservation priority. There have been few assessments, however, of the conservation value of IBAs for nonavian taxa. We combined past data with extensive new survey results for Uganda's IBAs in the most comprehensive assessment to date of the wider biodiversity value of a tropical country's IBA network. The combined data set included more than 35,000 site × species records for birds, butterflies, and woody plants at 86 Ugandan sites (23,400 km2), including 29 of the country's 30 IBAs, with data on additional taxa for many sites. Uganda's IBAs contained at least 70% of the country's butterfly and woody plant species, 86% of its dragonflies and 97% of its birds. They also included 21 of Uganda's 22 major vegetation types. For butterflies, dragonflies, and some families of plants assessed, species of high conservation concern were well represented (less so for the latter). The IBAs successfully represented wider biodiversity largely because many have distinctive avifaunas and, as shown by high cross-taxon congruence in complementarity, such sites tended to be distinctive for other groups too. Cross-taxon congruence in overall species richness was weaker and mainly associated with differences in site size. When compared with alternative sets of sites selected using complementarity-based, area-based, or random site-selection algorithms, the IBA network was efficient in terms of the number of sites required to represent species but inefficient in terms of total area. This was mainly because IBA selection considers factors other than area, however, which probably improves both the cost-effectiveness of the network and the persistence of represented species. Resumen:,El programa de Áreas de Importancia para las Aves (AIAs) de Birdlife International es el sistema global más desarrollado para la identificación de sitios de prioridad para la conservación. Sin embargo, ha habido pocas evaluaciones del valor de conservación de las AIAs para taxa no aviares. En la evaluación más integral, hasta la fecha, del valor de la biodiversidad en general de la red de AIAs de un país tropical, combinamos datos antiguos con los resultados de muestreos extensivos recientes de las AIAs de Uganda. El conjunto de datos combinados incluyó más de 35000 registros de sitios x especies de aves, mariposas y plantas leñosas en 86 sitios en Uganda (23400 km2), incluyendo 29 de las 30 AIAs del país, con datos sobre taxa adicionales en muchos sitios. Las AIAs de Uganda contenían por lo menos un 70% de las especies de mariposas y plantas leñosas del país, 86% de sus libélulas y 97% de sus aves. También incluyeron 21 de los 22 principales tipos de vegetación. En las mariposas, libélulas y algunas de las familias de plantas evaluadas, la representación de especies de alto interés para la conservación fue buena (menor en las plantas). Las Áreas de Importancia para las Aves representaron exitosamente a la biodiversidad en general principalmente porque muchas tienen avifaunas distintivas y, como muestra la alta congruencia trans-taxón en complementariedad, tales sitios tendieron a ser distintivos para otros grupos también. La congruencia trans-taxón en la riqueza de especies total fue más débil y se asoció principalmente con diferencias en el tamaño del sitio. Cuando se compara con conjuntos alternativos de sitios seleccionados mediante algoritmos basados en complementariedad, área o selección aleatoria de sitios, la red de AIAs fue eficiente en términos del número de sitios requeridos para representar especies, pero ineficiente en términos del área total. Sin embargo, esto se debió principalmente a que la selección de AIA considera factores distintos al área que probablemente mejoran tanto la efectividad de la red como la persistencia de las especies representadas. [source]


Spatial abundance structures in an assemblage of gall-forming sawflies

JOURNAL OF ANIMAL ECOLOGY, Issue 3 2004
M. A. McGeoch
Summary 1Examination of the fine-scale internal structure of species geographical ranges, and interspecific variation therein across landscapes, contributes to a more comprehensive understanding of the structure of geographical ranges. Two components of this internal structure that require further examination are the occurrence, extent and position of spatial autocorrelation, and relationships between the spatial abundance structures of closely related, ecologically similar species. 2Here we compare the abundance structures of an assemblage of gall-forming sawflies (Tenthredinidae) across a landscape. We identify the relative roles of spatial and non-spatial factors in explaining their abundance structures and test the hypothesis that sawfly density is explained by host plant quality, as has been demonstrated repeatedly at finer scales. We use these results to distinguish between alternative sets of mechanisms that may be operating at the landscape scale. 3Species densities were mainly multimodal across the landscape and significantly spatially structured, with patch, periodic and trend components. The abundance structures thus mimic those found generally for species across the full extent of their geographical ranges. 4Many abundance structure characteristics were unique to species, with differences in their correlogram profiles, distances over which densities were positively autocorrelated, and the absence of significant spatial structure in one species. 5In contrast to previous, fine-scale studies, host plant quality explained little of the variation in sawfly gall density across the landscape, whereas unexplained spatial structure contributed between 30% and 50%. Based on knowledge of the biology of these species and the absence of competitive interactions, species dispersal characteristics and the Moran effect are suggested as probable alternative hypotheses at this scale. 6Therefore, a spatial approach has identified the hierarchical nature of mechanisms underlying the population dynamics of this sawfly assemblage for the first time. Furthermore, it has highlighted the importance of spatial processes in explaining the densities of species at the landscape scale, as well as the individualistic nature of their abundance structures. [source]


Demographic Issues in Longevity Risk Analysis

JOURNAL OF RISK AND INSURANCE, Issue 4 2006
Eric Stallard
Fundamental to the modeling of longevity risk is the specification of the assumptions used in demographic forecasting models that are designed to project past experience into future years, with or without modifications based on expert opinion about influential factors not represented in the historical data. Stochastic forecasts are required to explicitly quantify the uncertainty of forecasted cohort survival functions, including uncertainty due to process variance, parameter errors, and model misspecification errors. Current applications typically ignore the latter two sources although the potential impact of model misspecification errors is substantial. Such errors arise from a lack of understanding of the nature and causes of historical changes in longevity and the implications of these factors for the future. This article reviews the literature on the nature and causes of historical changes in longevity and recent efforts at deterministic and stochastic forecasting based on these data. The review reveals that plausible alternative sets of forecasting assumptions have been derived from the same sets of historical data, implying that further methodological development will be needed to integrate the various assumptions into a single coherent forecasting model. Illustrative calculations based on existing forecasts indicate that the ranges of uncertainty for older cohorts' survival functions will be at a manageable level. Uncertainty ranges for younger cohorts will be larger and the need for greater precision will likely motivate further model development. [source]


Legal Validity: An Inferential Analysis,

RATIO JURIS, Issue 2 2008
GIOVANNI SARTOR
Its conceptual function is that of relating certain (alternative sets of) properties a norm may possess to the conclusion that the norm is legally binding, namely, that it deserves to be endorsed and applied in legal reasoning. Legal validity has to be distinguished from other, more demanding, normative ideas, such as moral bindingness or legal optimality. [source]