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Adaptation Strategies (adaptation + strategy)
Selected AbstractsMolecular Diversity of Vasotocin-Dependent Aquaporins Closely Associated with Water Adaptation Strategy in Anuran AmphibiansJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2010M. Suzuki Anuran amphibians represent the first vertebrates that adapted to terrestrial environments, and are successfully distributed around the world, even to forests and arid deserts. Many adult anurans have specialised osmoregulatory organs, in addition to the kidney (i.e. the ventral pelvic skin to absorb water from the external environments and a urinary bladder that stores water and reabsorbs it in times of need). Aquaporin (AQP), a water channel protein, plays a fundamental role in these water absorption/reabsorption processes. The anuran AQP family consists of at least AQP0-AQP5, AQP7-AQP10 and two anuran-specific types, designated as AQPa1 and AQPa2. For the three osmoregulatory organs, AQP3 is constitutively located in the basolateral membrane of the tight-junctioned epithelial cells, allowing water transport between the cytoplasm of these cells and the neighbouring tissue fluid at all times. On the other hand, AQPs at the apical side of the tight epithelial cells are different among these organs, and are named kidney-type AQP2, ventral pelvic skin-type AQPa2 and urinary bladder-type AQPa2. All of them show translocation from the cytoplasmic pool to the apical plasma membrane in response to arginine vasotocin, thereby regulating water transport independently in each osmoregulatory organ. It was further revealed that, in terrestrial and arboreal anurans, the bladder-type AQPa2 is expressed in the pelvic skin, together with the pelvic skin-type AQPa2, potentially facilitating water absorption from the pelvic skin. By contrast, Xenopus has lost the ability to efficiently produce pelvic skin-type AQPa2 (AQP-x3) because Cys-273 of AQP-x3 and/or Cys-273-coding region of AQPx3 mRNA attenuate gene expression at a post-transcriptional step, presumably leading to the prevention of excessive water influx in this aquatic species. Collectively, the acquisition of two forms of AQPa2 and the diversified regulation of their gene expression appears to provide the necessary mechanisms for the evolutionary adaptation of anurans to a wide variety of ecological environments. [source] Prediction of temporal gene expressionFEBS JOURNAL, Issue 22 2002Metabolic optimization by re-distribution of enzyme activities A computational approach is used to analyse temporal gene expression in the context of metabolic regulation. It is based on the assumption that cells developed optimal adaptation strategies to changing environmental conditions. Time-dependent enzyme profiles are calculated which optimize the function of a metabolic pathway under the constraint of limited total enzyme amount. For linear model pathways it is shown that wave-like enzyme profiles are optimal for a rapid substrate turnover. For the central metabolism of yeast cells enzyme profiles are calculated which ensure long-term homeostasis of key metabolites under conditions of a diauxic shift. These enzyme profiles are in close correlation with observed gene expression data. Our results demonstrate that optimality principles help to rationalize observed gene expression profiles. [source] Current and Future Trends of Climatic Extremes in SwitzerlandGEOGRAPHY COMPASS (ELECTRONIC), Issue 4 2007Martin Beniston This article provides an overview of extreme climatic events that are a feature of current and future climate that require full understanding if they are to be assessed in terms of social and economic costs. A review is made of the type of events that are important in mid-latitudes, with examples taken from the heat waves, floods and wind-storms that have affected Switzerland during the twentieth century. Regional climate model results are also presented for a scenario conducted over Europe. These simulations suggest that there may be significant shifts in the frequency and intensity of many forms of extremes as a warmer global climate progressively replaces current climate. In view of the potential losses in human, economic and environmental terms, extreme events and their future evolution need to carefully assessed in order to formulate appropriate adaptation strategies aimed at minimizing the negative impacts that extremes are capable of generating. [source] The role of waves in ice-jam flooding of the Peace-Athabasca DeltaHYDROLOGICAL PROCESSES, Issue 19 2007Spyros Beltaos Abstract Since the late 1960s, a paucity of ice-jam flooding in the lower Peace River has resulted in prolonged dry periods and considerable reduction in the area covered by lakes and ponds that provide habitat for aquatic life in the Peace-Athabasca Delta (PAD) region. To identify the causes of this trend, and to develop mitigation or adaptation strategies under present and future climatic conditions, it is necessary to understand the mechanisms that lead to breakup of the ice cover and jamming within the delta reach of Peace River. Because the lower Peace is extremely flat, the long-period waves caused by spring snowmelt are not generally capable of dislodging the winter ice cover, even under conditions of very high flow. The ice cover decays in place and rubble generation, an essential condition for ice jamming, does not occur. However, major jams do, on occasion, form in the middle section of the river and make their way to the delta via repeated releases and stalls. Each release generates a steep wave which can greatly amplify the hydrodynamic forces that are applied on the ice cover and bring about its dislodgment. This is quantified for the lower Peace River by applying recently developed methodology to local hydrometric data. Detailed in situ observations in the spring of 2003, and additional data from 1997 and 2002, fully corroborate this conclusion. Implications to other flat rivers of northern Canada are discussed. Copyright © 2007 Crown in the right of Canada. Published by John Wiley & Sons, Ltd. [source] Migration, Motherhood, Marriage: Cross-Cultural Adaptation of North American Immigrant Mothers in IsraelINTERNATIONAL MIGRATION, Issue 1 2009Laura I. Sigad This study probes the cross-cultural adaptation patterns of North American women who immigrated to Israel with their Israeli-born husbands (or married there) and are mothers in their new country. In order to undertake a cultural analysis of the interplay between immigration, motherhood and bicultural marriage, we examine: the effects of motherhood and North American culture of origin on cross-cultural adaptation; the effects of immigration to Israel on motherhood and childrearing; the influence of family of origin on the immigrant motherhood experience; and the role of Israeli husbands and their families in the women's cross-cultural adaptation process. We study patterns for the entire group as well as bringing out individual differences. Our main finding is that motherhood serves as the principal social link to the Israeli host society. The high status of North American culture and English proficiency facilitate cross-cultural adaptation in Israel. Our findings reveal transnationalist tendencies co-existing with various adaptation strategies. We propose an expansion of previous acculturation models to accommodate this dual modus vivendi. [source] Permafrost thermal state in the polar Northern Hemisphere during the international polar year 2007,2009: a synthesisPERMAFROST AND PERIGLACIAL PROCESSES, Issue 2 2010Vladimir E. Romanovsky Abstract The permafrost monitoring network in the polar regions of the Northern Hemisphere was enhanced during the International Polar Year (IPY), and new information on permafrost thermal state was collected for regions where there was little available. This augmented monitoring network is an important legacy of the IPY, as is the updated baseline of current permafrost conditions against which future changes may be measured. Within the Northern Hemisphere polar region, ground temperatures are currently being measured in about 575 boreholes in North America, the Nordic region and Russia. These show that in the discontinuous permafrost zone, permafrost temperatures fall within a narrow range, with the mean annual ground temperature (MAGT) at most sites being higher than ,2°C. A greater range in MAGT is present within the continuous permafrost zone, from above ,1°C at some locations to as low as ,15°C. The latest results indicate that the permafrost warming which started two to three decades ago has generally continued into the IPY period. Warming rates are much smaller for permafrost already at temperatures close to 0°C compared with colder permafrost, especially for ice-rich permafrost where latent heat effects dominate the ground thermal regime. Colder permafrost sites are warming more rapidly. This improved knowledge about the permafrost thermal state and its dynamics is important for multidisciplinary polar research, but also for many of the 4 million people living in the Arctic. In particular, this knowledge is required for designing effective adaptation strategies for the local communities under warmer climatic conditions. Copyright © 2010 John Wiley & Sons, Ltd. [source] Multi-level Governance and Global Climate Change in East AsiaASIAN ECONOMIC POLICY REVIEW, Issue 1 2010Miranda A. SCHREURS Q54; F55; H77 Climate change is an issue that requires integrated action at multiple levels of government and within the spheres of politics, economics, and society. National, regional, and local governments have both distinct and complementary roles in developing climate mitigation and adaptation strategies. Compared with the attention that has been given to international and national activities in East Asia, relatively limited attention has been paid to the role of urban and regional governments in combating global climate change. Cities and provinces are initiating their own climate action plans, positioning themselves as environmental model cities, and joining local, national, and international networks for climate change. This article examines urban and prefectural climate policies in China, Japan, and South Korea within a multilevel governance framework. [source] Impacts of climate change on lower Murray irrigation,AUSTRALIAN JOURNAL OF AGRICULTURAL & RESOURCE ECONOMICS, Issue 3 2009Jeff Connor This article evaluates irrigated agriculture sector response and resultant economic impacts of climate change for a part of the Murray Darling Basin in Australia. A water balance model is used to predict reduced basin inflows for mild, moderate and severe climate change scenarios involving 1, 2 and 4°C warming, and predict 13, 38 and 63% reduced inflows. Impact on irrigated agricultural production and profitability are estimated with a mathematical programming model using a two-stage approach that simultaneously estimates short and long-run adjustments. The model accounts for a range of adaptive responses including: deficit irrigation, temporarily following of some areas, permanently reducing the irrigated area and changing the mix of crops. The results suggest that relatively low cost adaptation strategies are available for a moderate reduction in water availability and thus costs of such a reduction are likely to be relatively small. In more severe climate change scenarios greater costs are estimated. Adaptations predicted include a reduction in total area irrigated and investments in efficient irrigation. A shift away from perennial to annual crops is also predicted as the latter can be managed more profitably when water allocations in some years are very low. [source] Adaptation to climate change in the European union: efficiency versus equity considerationsENVIRONMENTAL POLICY AND GOVERNANCE, Issue 3 2010Stine Aakre Abstract EU climate policy based on reduction (mitigation) of greenhouse gas emissions is coupled with measures aimed at responding efficiently to the unavoidable consequences of climate change (adaptation). However, as the European Commission stated recently in its Green and White Papers on adaptation in Europe, there is still need to develop an overall EU adaptation strategy. Moreover, such a strategy should take into consideration both efficiency and equity concerns. In this article we propose a framework for EU adaptation policy that addresses the two concerns and which enables a transparent decision-making process. In the proposed scheme universal weightings of the individual policy objectives have to be agreed upon prior to actual decision-making. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment. [source] Lower bound limit analysis with adaptive remeshingINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2005Andrei V. Lyamin Abstract The objective of this work is to present an adaptive remeshing procedure for lower bound limit analysis with application to soil mechanics. Unlike conventional finite element meshes, a lower bound grid incorporates statically admissible stress discontinuities between adjacent elements. These discontinuities permit large stress jumps over an infinitesimal distance and reduce the number of elements needed to predict the collapse load accurately. In general, the role of the discontinuities is crucial as their arrangement and distribution has a dramatic influence on the accuracy of the lower bound solution (Limit Analysis and Soil Plasticity, 1975). To ensure that the discontinuities are positioned in an optimal manner requires an error estimator and mesh adaptation strategy which accounts for the presence of stress singularities in the computed stress field. Recently, Borges et al. (Int. J. Solids Struct. 2001; 38:1707,1720) presented an anisotropic mesh adaptation strategy for a mixed limit analysis formulation which used a directional error estimator. In the present work, this strategy has been tailored to suit a discontinuous lower bound formulation which employs the stresses and body forces as primary unknowns. The adapted mesh has a maximum density of discontinuities in the direction of the maximum rate of change in the stress field. For problems involving strong stress singularities in the boundary conditions (e.g. a strip footing), the automatic generation of discontinuity fans, centred on the singular points, has been implemented. The efficiency of the proposed technique is demonstrated by analysis of two classical soil mechanics problems; namely the bearing capacity of a rigid strip footing and the collapse of a vertical cut. Copyright © 2005 John Wiley & Sons, Ltd. [source] New approach to refinery process simulation with adaptive composition representationAICHE JOURNAL, Issue 3 2004Heiko Briesen Abstract The established technique for simulation of refinery processes is the use of pseudocomponents. However, in order to increase the economical benefit of plant operation, it seems inevitable to include molecular information in petroleum mixtures characterization. This will lead to a strong increase of problem size. For this new class of models, there currently seems to be no special algorithms available. The classic pseudocomponent approach is compared with a newly developed solution strategy, which is explicitly developed to efficiently solve simulation problems with a high detail in composition representation. The new solution strategy is an adaptive multigrid method based on a wavelet,Galerkin discretization. With the wavelet,Galerkin discretization the model can easily be formulated on various levels of detail. In an iterative procedure the multigrid concept exploits these different formulations to construct correction-term approximations to the true solution. The discretization of these correction-term models is now done with a detail in composition representation that is determined by a residual-based adaptation strategy. The proposed method has been implemented for a simple 9-stage distillation column and tested for a variety of feed mixtures. In all investigated tests the proposed method proved to be superior to the conventional pseudocomponent approach in terms of accuracy and efficiency. © 2004 American Institute of Chemical Engineers AIChE J, 50: 633,645, 2004 [source] | |||||||||||||||||||