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Different Scenarios (different + scenario)
Selected AbstractsNumerical modelling of the potential effects of a dam on a coastal aquifer in S. SpainHYDROLOGICAL PROCESSES, Issue 9 2009M. L. Calvache Abstract This study presents the results of a three-dimensional variable-density numerical modelling of the Motril-Salobreña coastal aquifer and the possible effects of the entry into service in May 2005 of the Rules Dam, located just 17 km from the coast. Present parameters of the Motril-Salobreña aquifer show that the system's conditions are very similar to a natural regime. The dam will substantially alter aquifer recharge, as the entry flow through the alluvial sediments of the Guadalfeo River will be entirely cut off or drastically reduced. Different scenarios reproducing the possible evolution of the aquifer under operation of the Rules Dam have been modelled. In most cases, results indicate that the conditions of the aquifer would worsen, with a general advance of the freshwater,saltwater interface. The area with most risk of saltwater intrusion is the old mouth of the Guadalfeo River, where the mixing zone could advance 1200 m inland. It is proposed that maintaining a 5,6 Mm3 year,1 ,ecological flow' in the Guadalfeo River could prevent this saline advance. This application demonstrates that variable-density models are potentially useful tools for estimating the effects of dams on the hydrodynamic and hydrochemical conditions of a coastal aquifer. Copyright © 2009 John Wiley & Sons, Ltd. [source] Soil frost effects on soil water and runoff dynamics along a boreal transect: 2.HYDROLOGICAL PROCESSES, Issue 6 2001Simulations Abstract A physically based SVAT-model was tested with soil and snow physical measurements, as well as runoff data from an 8600 m2 catchment in northern Sweden in order to quantify the influence of soil frost on spring snowmelt runoff in a moderately sloped, boreal forest. The model was run as an array of connected profiles cascading to the brook. For three winter seasons (1995,98) it was able to predict the onset and total accumulation of the runoff with satisfactory accuracy. Surface runoff was identified as only a minor fraction of the total runoff occurring during short periods in connection with ice blocking of the water-conducting pores. Little surface runoff, though, does not mean that soil frost is unimportant for spring runoff. Simulations without frost routines systematically underestimated the total accumulated runoff. The possibility of major frost effects appearing in response to specific combinations of weather conditions were also tested. Different scenarios of critical initial conditions for the winter, e.g. high water saturation and delayed snow accumulation leading to an increased frost penetration, were tested. These showed that under special circumstances there is potential for increased spring runoff due to soil frost. Copyright © 2001 John Wiley & Sons, Ltd. [source] Drainage and salinity assessment in the Huinong Canal Irrigation District, Ningxia, China,IRRIGATION AND DRAINAGE, Issue 2 2005Peter Hollanders irrigation; drainage; salinisation; développement durable Abstract In the Huinong Canal Irrigation District, Ningxia, China, annually almost half of the amount of irrigation water, which is supplied from the Yellow River, is drained back to the river through an open drainage system. Waterlogging and salinization occur in parts of the irrigated area and part of the water drains to the surrounding desert. While 85,90% of inflow to the area is irrigation water there are good possibilities for water saving. To analyse water movement at field level and resulting drainage needs, from autumn 1998 until spring 2001 observations were made in two experimental areas: Pingluo and Huinong. The data were used for the calibration and validation of three computer models: SWAP, MODFLOW and DUFLOW. Different scenarios of water and salt behaviour in the unsaturated and saturated zone were simulated, as well as the flow through one of the main drains. The effects of various irrigation amounts and groundwater tables on crop growth, percolation and drainage needs were analysed. The present average irrigation water application during the growing season is 630,mm. On average 15% of the supplied water (665 million m3,yr,1) remains in the area. This is mainly irrigation water that was not used by the crops and did not reach the drainage system. It was found that an irrigation level of 75% of the present practice with a groundwater table of 1.0,m below the surface during the growing season gave the best results. Under such a practice the soil salinity will fluctuate around 3,3.5,dS,m,1, resulting in a good growth of wheat and a yield reduction for maize of about 20%. When adequate amounts of irrigation water are supplied in combination with local drainage improvements, the areas with middle and low-yielding crops can be reduced, as well as the area of wasteland. Copyright © 2005 John Wiley & Sons, Ltd. Annuellement presque la moitié de la quantité d'eau d'irrigation dans le district d'irrigation du canal Huinong, Ningxia, Chine, alimenté par la Rivière Jaune, est retournée à la rivière par un système de drainage à ciel ouvert. Des cas de saturation d'eau et de salinisation surgissent dans certaines parties de la zone irriguée et une partie de l'eau suinte vers le désert environnant. Comme 85,90% de l'entrée de l'eau dans la zone est de l'eau d'irrigation il y a de bonnes possibilités pour économiser de l'eau. Pour analyser la circulation de l'eau au niveau du champ et la nécessité de drainage des observations ont été effectuées pendant la période d'automne 1998 jusqu'au printemps 2001 dans deux zones expérimentales, Pingluo et Huinong. Les données rassemblées ont servi pour le calibrage et la validation de trois modèles informatiques: SWAP, MODFLOW et DUFLOW. Ces modèles ont été employés pour simuler plusieurs scénarios de comportement de l'eau et du sel dans la zone non saturée et dans la zone saturée tout comme l'écoulement par un des tuyaux d'écoulement principaux: le cinquième tuyau d'écoulement. L'effet de l'apport de différentes quantités d'eau d'irrigation, de différents niveaux de la nappe phréatique sur la croissance des cultures, la percolation et la nécessité de drainage a été analysé. L'actuel apport d'eau d'irrigation est de 630,mm en moyenne pendant la saison de croissance. Quinze pour cent en moyenne de l'eau fournie (665 millions m3/année) reste dans la zone, principalement de l'eau d'irrigation qui n'a pas servi aux cultures et qui n'a pas atteint le système de drainage. Un niveau d'irrigation représentant 75% des valeurs actuelles et une surface de la nappe phréatique de 1.0,m sous la surface donnent les meilleurs résultats pendant la saison de croissance. De tels apports entretiennent une salinisation du sol qui fluctuera entre environ 3 et 3.5,dS,m,1, donnant un bon résultat de la croissance du blé et une diminution du rendement pour le maïs d'environ 20%. Lorsque l'alimentation par des quantités adéquates d'eau d'irrigation sera assurée en combinaison avec des améliorations du drainage local, la zone donnant des récoltes moyennes et basses peut être réduite ainsi que les zones incultes. Copyright © 2005 John Wiley & Sons, Ltd. [source] Resistivity measurements of Mo6S3I6 nanowire networksPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 13 2006B. Ber Abstract We present measurements of resistivity on Mo6S3I6 nanowire networks as a function of temperature, moisture and high-temperature processing conditions. The room-temperature conductivity of as-grown material is s300 K , 0.04 S/m with a linear I ,V characteristic. The temperature dependence of conductivity of pristine samples closely follows the expression s = s0 exp (,T0/T)b, where b = 1/4. Removal of interstitial iodine from the network by annealing in vacuum gives rise to a cross-over to b = 1/2 and an increase in conductivity. Different scenarios for observed cross-over are discussed. The introduction of water vapour leads to a decrease in conductivity and reveals that the resistivity of the network is sensitive to interstitial water molecules, which is interesting for potential chemical sensor applications. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Cladistic analysis of languages: Indo-European classification based on lexicostatistical dataCLADISTICS, Issue 2 2003ina Rexová The phylogeny of the Indo-European (IE) language family is reconstructed by application of the cladistic methodology to the lexicostatistical dataset collected by Dyen (about 200 meanings, 84 speech varieties, the Hittite language used as a functional outgroup). Three different methods of character coding provide trees that show: (a) the presence of four groups, viz., Balto-Slavonic clade, Romano-Germano-Celtic clade, Armenian-Greek group, and Indo-Iranian group (the two last groups possibly paraphyletic); (b) the unstable position of the Albanian language; (c) the unstable pattern of the basalmost IE differentiation; but (d) the probable existence of the Balto-Slavonic,Indo-Iranian ("satem") and the Romano-Germano-Celtic (+Albanian?) superclades. The results are compared with the phenetic approach to lexicostatistical data, the results of which are significantly less informative concerning the basal pattern. The results suggest a predominantly branching pattern of the basic vocabulary phylogeny and little borrowing of individual words. Different scenarios of IE differentiation based on archaeological and genetic information are discussed. [source] Using Web 2.0 for scientific applications and scientific communitiesCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 5 2009Marlon E. Pierce Abstract Web 2.0 approaches are revolutionizing the Internet, blurring lines between developers and users and enabling collaboration and social networks that scale into the millions of users. As discussed in our previous work, the core technologies of Web 2.0 effectively define a comprehensive distributed computing environment that parallels many of the more complicated service-oriented systems such as Web service and Grid service architectures. In this paper we build upon this previous work to discuss the applications of Web 2.0 approaches to four different scenarios: client-side JavaScript libraries for building and composing Grid services; integrating server-side portlets with ,rich client' AJAX tools and Web services for analyzing Global Positioning System data; building and analyzing folksonomies of scientific user communities through social bookmarking; and applying microformats and GeoRSS to problems in scientific metadata description and delivery. Copyright © 2009 John Wiley & Sons, Ltd. [source] A dynamic admission control scheme to manage contention on shared computing resourcesCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 2 2009Percival Xavier Abstract A virtual organization is established when physical organizations collaborate to share their computing resources with the aim of serving each other when there is a likelihood of insufficient local resources during peak resource usage periods at any organization. Contention becomes a potential problem when a large number of requests, which can overwhelm the aggregate capacity of shared resources, are submitted from the participating organizations coincidentally at the same period. In particular, when a small number of requests that require large amounts of computing resources are admitted in place of a large number of requests that require less computing resources, the overall system performance, in terms of admission ratio, can deteriorate significantly. Hence, admission control is necessary to reduce resource oversubscription. Because domain-shared computing resources are likely to be combined to form a large-scale system, it is not possible to define a fixed admission policy solely based on the request's CPU and execution time requirements. In this paper, we introduce an admission control framework, based on a pricing model, for a multi-domain-shared computing infrastructure. The performance of the admission control framework is evaluated under different scenarios that contribute to the overall degree of competition for shared resources. The results are presented and analyzed in this paper. Copyright © 2008 John Wiley & Sons, Ltd. [source] Integrating species life-history traits and patterns of deforestation in amphibian conservation planningDIVERSITY AND DISTRIBUTIONS, Issue 1 2010C. G. Becker Abstract Aim, To identify priority areas for amphibian conservation in southeastern Brazil, by integrating species life-history traits and patterns of deforestation. Location, State of São Paulo, Brazil. Methods, We used the software Marxan to evaluate different scenarios of amphibian conservation planning. Our approach differs from previous methods by explicitly including two different landscape metrics; habitat split for species with aquatic larvae, and habitat loss for species with terrestrial development. We evaluated the effect of habitat requirements by classifying species breeding habitats in five categories (flowing water, still water permanent, still water temporary, bromeliad or bamboo, and terrestrial). We performed analyses using two scales, grid cells and watersheds and also considered nature preserves as protected areas. Results, We found contrasting patterns of deforestation between coastal and inland regions. Seventy-six grid cells and 14 watersheds are capable of representing each species at least once. When accounting for grid cells already protected in state and national parks and considering species habitat requirements we found 16 high-priority grid cells for species with one or two reproductive habitats, and only one cell representing species with four habitat requirements. Key areas for the conservation of species breeding in flowing and permanent still waters are concentrated in southern state, while those for amphibians breeding in temporary ponds are concentrated in central to eastern zones. Eastern highland zones are key areas for preserving species breeding terrestrially by direct or indirect development. Species breeding in bromeliads and bamboos are already well represented in protected areas. Main conclusions, Our results emphasize the need to integrate information on landscape configuration and species life-history traits to produce more ecologically relevant conservation strategies. [source] Modelling land use changes and their impact on soil erosion and sediment supply to riversEARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2002Anton J. J. Van Rompaey Abstract The potential for surface runoff and soil erosion is strongly affected by land use and cultivation. Therefore the modelling of land use changes is important with respect to the prediction of soil degradation and its on-site and off-site consequences. Land use changes during the past 250 years in the Dijle catchment (central Belgium) were analysed by comparing four historical topographic maps (1774, 1840, 1930 and 1990). A combination of land use transformation maps and biophysical land properties shows that certain decision rules are used for the conversion of forest into arable land or vice versa. During periods of increasing pressure on the land, forests were cleared mainly on areas with low slope gradients and favourable soil conditions, while in times of decreasing pressure land units with steep and unfavourable soil conditions were taken out of production. Possible future land use patterns were generated using stochastic simulations based on land use transformation probabilities. The outcome of these simulations was used to assess the soil erosion risk under different scenarios. The results indicate that even a relatively limited land use change, from forest to arable land or vice versa, has a significant effect on regional soil erosion rates and sediment supply to rivers. Copyright © 2002 John Wiley & Sons, Ltd. [source] Ground motion duration effects on nonlinear seismic responseEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 1 2006Iunio Iervolino Abstract The study presented in this paper addresses the question of which nonlinear demand measures are sensitive to ground motion duration by statistical analyses of several case studies. A number of single degree of freedom (SDOF) structures were selected considering: (1) four oscillation periods; (2) three evolutionary and non-evolutionary hysteretic behaviours; (3) two target ductility levels. Effects of duration are investigated, by nonlinear dynamic analysis, with respect to six different demand indices ranging from displacement ductility ratio to equivalent number of cycles. Input is made of six real accelerogram sets representing three specific duration scenarios (small, moderate and large duration). For all considered demand quantities time-history results are formally compared by statistical hypothesis test to asses the difference, if any, in the demand concerning different scenarios. Incremental dynamic analysis curves are used to evaluate duration effect as function of ground motion intensity (e.g. spectral acceleration corresponding to the SDOF's oscillation period). Duration impact on structural failure probability is evaluated by fragility curves. The results lead to the conclusion that duration content of ground motion is statistically insignificant to displacement ductility and cyclic ductility demand. The conclusions hold regardless of SDOF's period and hysteretic relationship investigated. Copyright © 2005 John Wiley & Sons, Ltd. [source] War and the global economyECONOMIC OUTLOOK, Issue 1 2002Article first published online: 5 FEB 200 Recent months have seen the adoption of an increasingly belligerent stance towards Iraq on the parts of the US and the UK in particular, signalling a shift from the policy of containment that has been in place since the last Gulf War, and towards a more aggressive policy. As yet, it is unclear whether this increased belligerence will culminate in a renewed full,scale military engagement with Iraq, to achieve the much vaunted ,regime change', or whether the outcome will be an agreement to a new programme of weapons inspections. But the risk of a military conflict appears to have increased. This article assesses the potential economic implications of such a conflict, exploring different scenarios for how it might evolve, and their impact on oil prices and global growth. [source] Shrimp,a dynamic model of heavy-metal uptake in aquatic macrofaunaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2001Teresa Castro Simas Abstract A dynamic model for prediction of bioaccumulation in aquatic macrofauna is described. The model, entitled SHRIMP (Simulation of Heavy-metal Rate of Intake for Macrofaunal sPecies), consists of five coupled submodels, which simulate individual growth, population dynamics, metal transport in the abiotic part of the system, metal bioaccumulation at the organism level, and upscaling of individual contamination to the population scale. The sublethal effects of metal toxicity on individual and population levels are shown to act through the reduction of individual growth rates. The model was tested for cadmium and mercury using epibenthic crustacea from an estuarine system. Individual and population patterns of bioaccumulation were analyzed by comparing the simulated results of five different scenarios of dissolved metal concentrations. Model results suggest that the subtle effect of growth reduction due to metal toxicity is sufficient to cause a decrease on population numbers simply by affecting the growth of the mature females and males. [source] Spatio-temporal statistical modelling of significant wave heightENVIRONMETRICS, Issue 1 2009A. Baxevani Abstract In this paper, we construct a homogeneous spatio-temporal model to describe the variability of significant wave height over small regions of the sea and over short periods of time. Then, the model is extended to a non-homogeneous one that is valid over larger areas of the sea and for time periods of up to 10 h. To validate the proposed model, we reconstruct the significant wave height surface under different scenarios and then compare it to satellite measurements and the C-ERA-40 field. Copyright © 2008 John Wiley & Sons, Ltd. [source] ORIGINAL ARTICLE: Probability of emergence of antimalarial resistance in different stages of the parasite life cycleEVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 1 2009Wirichada Pongtavornpinyo Abstract Understanding the evolution of drug resistance in malaria is a central area of study at the intersection of evolution and medicine. Antimalarial drug resistance is a major threat to malaria control and directly related to trends in malaria attributable mortality. Artemisinin combination therapies (ACT) are now recommended worldwide as first line treatment for uncomplicated malaria, and losing them to resistance would be a disaster for malaria control. Understanding the emergence and spread of antimalarial drug resistance in the context of different scenarios of antimalarial drug use is essential for the development of strategies protecting ACTs. In this study, we review the basic mechanisms of resistance emergence and describe several simple equations that can be used to estimate the probabilities of de novo resistance mutations at three stages of the parasite life cycle: sporozoite, hepatic merozoite and asexual blood stages; we discuss the factors that affect parasite survival in a single host in the context of different levels of antimalarial drug use, immunity and parasitaemia. We show that in the absence of drug effects, and despite very different parasite numbers, the probability of resistance emerging at each stage is very low and similar in all stages (for example per-infection probability of 10,10,10,9 if the per-parasite chance of mutation is 10,10 per asexual division). However, under the selective pressure provided by antimalarial treatment and particularly in the presence of hyperparasitaemia, the probability of resistance emerging in the blood stage of the parasite can be approximately five orders of magnitude higher than in the absence of drugs. Detailed models built upon these basic methods should allow us to assess the relative probabilities of resistance emergence in the different phases of the parasite life cycle. [source] Transgenic fish: an evaluation of benefits and risksFISH AND FISHERIES, Issue 2 2000N. Maclean Transgenic fish have many potential applications in aquaculture, but also raise concerns regarding the possible deleterious effects of escaped or released transgenic fish on natural ecosystems. In this review the potential applications of transgenic fish are considered, the probable benefits reviewed, the possible risks to the environment identified and the measures which might be taken to minimize these risks are evaluated. Growth trials of transgenic fish have already been carried out in outdoor facilities and some of these are discussed in the light of possible risks and benefits. Regarding the hazards associated with release or escape, whilst there is some evidence to suggest that transgenic fish may be less fit compared to their wild counterparts, there is insufficient evidence to say that this will be true in all cases. Using mathematical models, we have attempted to predict the magnitude of the genetic effects in a range of different scenarios. A number of possible containment techniques are considered, amongst which containment by sterility is probably the most promising. This can be engineered either by triploidy or by transgenic methods. The conclusions include a tabulated balance sheet of likely benefits and risks, with appropriate weighting. [source] The impacts of Miscanthus×giganteus production on the Midwest US hydrologic cycleGCB BIOENERGY, Issue 4 2010ANDY VANLOOCKE Abstract Perennial grasses are being considered as candidates for biofuel feedstocks to provide an alternative energy source to fossil fuels. Miscanthus×giganteus (miscanthus), in particular, is a grass that is predicted to provide more energy per sown area than corn ethanol and reduce net carbon dioxide emissions by increasing the storage of carbon belowground. Miscanthus uses more water than Zea mays (maize), mainly as a result of a longer growing season and higher productivity. Conversion of current land use for miscanthus production will likely disrupt regional hydrologic cycles, yet the magnitude, timing, and spatial distribution of effects are unknown. Here, we show the effects of five different scenarios of miscanthus production on the simulated Midwest US hydrologic cycle. Given the same historic precipitation observations, our ecosystem model simulation results show that on an annual basis miscanthus uses more water than the ecosystems it will likely replace. The actual timing and magnitude of increased water loss to the atmosphere depends on location; however, substantial increases only occur when miscanthus fraction cover exceeds 25% in dry regions and 50% in nearly all of the Midwest. Our results delineate where large-scale land use conversion to perennial biofuel grasses might deplete soil water resources. Given the fact that some watersheds within the Midwest already have depleted water resources, we expect our results to inform decisions on where to grow perennial grasses for biofuel use to ensure sustainability of energy and water resources, and to minimize the potential for deleterious effects to water quantity and quality. [source] On the Interaction of Risk and Time Preferences: An Experimental StudyGERMAN ECONOMIC REVIEW, Issue 3 2001Vital Anderhub Experimental studies of risk and time preference typically focus on one of the two phenomena. The goal of this paper is to investigate the (possible) correlation between subjects' attitude to risk and their time preference. For this sake we ask 61 subjects to price a simple lottery in three different scenarios. At the first, the lottery premium is paid ,now'. At the second, it is paid ,later'. At the third, it is paid ,even later,. By comparing the certainty equivalents offered by the subjects for the three lotteries, we test how time and risk preferences are interrelated. Since the time interval between ,now' and ,later' is the same as between ,later' and ,even later', we also test the hypothesis of hyperbolic discounting. The main result is a statistically significant negative correlation between subjects' degrees of risk aversion and their (implicit) discount factors. Moreover, we show that the negative correlation is independent of the method used to elicit certainty equivalents (willingness to pay versus willingness to accept). [source] Environmental isotopic and hydrochemical characteristics of groundwater systems in Daying and Qicun geothermal fields, Xinzhou Basin, Shanxi, ChinaHYDROLOGICAL PROCESSES, Issue 22 2010Dongmei Han Abstract The conceptual hydrogeological model of the low to medium temperature Daying and Qicun geothermal fields has been proposed, based on hydrochemical characteristics and isotopic compositions. The two geothermal fields are located in the Xinzhou basin of Shanxi, China and exhibit similarities in their broad-scale flow patterns. Geothermal water is derived from the regional groundwater flow system of the basin and is characterized by Cl·SO4 -Na type. Thermal water is hydrochemically distinct from cold groundwater having higher total dissolved solids (TDS) (>0·8 g/l) and Sr contents, but relatively low Ca, Mg and HCO3 contents. Most shallow groundwater belongs to local flow systems which are subject to evaporation and mixing with irrigation returns. The groundwater residence times estimated by tritium and 14C activities indicate that deep non-thermal groundwater (130,160 m) in the Daying region range from modern (post-1950s) in the piedmont area to more than 9·4 ka BP (Before Present) in the downriver area and imply that this water belong to an intermediate flow system. Thermal water in the two geothermal fields contains no detectable active 14C, indicating long residence times (>50 ka), consistent with this water being part of a large regional flow system. The mean recharge elevation estimated by using the obtained relationship Altitude (m) = , 23·8 × ,2H (, ) , 121·3, is 1980 and 1880 m for the Daying and Qicun geothermal fields, respectively. The annual infiltration rates in the Daying and Qicun geothermal fields can be estimated to be 9029 × 103 and 4107 × 103 m3/a, respectively. The variable 86Sr/87Sr values in the thermal and non-thermal groundwater in the two fields reflect different lithologies encountered along the flow path(s) and possibly different extents of water-rock interaction. Based on the analysis of groundwater flow systems in the two geothermal fields, hydrogeochemical inverse modelling was performed to indicate the possible water-rock interaction processes that occur under different scenarios. Copyright © 2010 John Wiley & Sons, Ltd. [source] Life and death within germinal centres: a double-edged swordIMMUNOLOGY, Issue 2 2002Liliana Guzman-Rojas Summary Within germinal centres, B lymphocytes are destined to die by apoptosis via Fas signalling, unless they are positively rescued by antigen and by signals initiated by CD40,CD154 interactions. Thus, while the germinal centre microenvironment can become a virtual graveyard for most B lymphocytes that fail to bind antigen with high affinity, it concomitantly provides the necessary stimuli for the survival of cells that successfully accomplish affinity maturation. Such dichotomy in the physiology of germinal centre reaction that results in survival of the functional B-cell repertoire and the elimination of abnormal cells, dictates the fate towards B-cell homeostasis or disease. Consequently, the death and survival-signalling arms within germinal centres predominantly reside on the timely and controlled expression of Fas and its ligand (FasL), and CD40 and CD154, respectively. In keeping with this notion, lymphoproliferation or deficient immunity are documented landmarks of inactivation of either the Fas/FasL or CD40/CD154 signalling pathways. The present review considers two different scenarios in the control of B-cell survival and death within germinal centres. The first is an idealistic scenario, in which a discriminatory and co-ordinate signalling initiated by the CD40/CD154 and Fas/FasL pairs, respectively, leads the rescue of the functional B-cell repertoire and the elimination of the abnormal phenotype. The second is a gloomy scenario in which both the lack and the hyperexpression of either receptor/ligand pairs, are seen as equally deleterious. [source] The integration of ecological risk assessment and structured decision making into watershed managementINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 1 2007Dan W Ohlson Abstract Watershed management processes continue to call for more science and improved decision making that take into account the full range of stakeholder perspectives. Increasingly, the core principles of ecological risk assessment (i.e., the development and use of assessment endpoints and conceptual models, conducting exposure and effects analysis) are being incorporated and adapted in innovative ways to meet the call for more science. Similarly, innovative approaches to adapting decision analysis tools and methods for incorporating stakeholder concerns in complex natural resource management decisions are being increasingly applied. Here, we present an example of the integration of ecological risk assessment with decision analysis in the development of a watershed management plan for the Greater Vancouver Water District in British Columbia, Canada. Assessment endpoints were developed, ecological inventory data were collected, and watershed models were developed to characterize the existing and future condition of 3 watersheds in terms of the potential risks to water quality. Stressors to water quality include sedimentation processes (landslides, streambank erosion) and forest disturbance (wildfire, major insect or disease outbreak). Three landscape-level risk management alternatives were developed to reflect different degrees of management intervention. Each alternative was evaluated under different scenarios and analyzed by explicitly examining value-based trade-offs among water quality, environmental, financial, and social endpoints. The objective of this paper is to demonstrate how the integration of ecological risk assessment and decision analysis approaches can support decision makers in watershed management. [source] Impact of climate variability on Alpine glaciers in northwestern ItalyINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 15 2007Sandro Calmanti Abstract We analyzed glacier snout fluctuation data in Piedmont and Val d'Aosta (Italy) and studied the impact of climate variability on valley glaciers in the western Italian Alps. The study period covered about 70 years in the 20th century; we focused on the last 50 years where a large number of temperature and precipitation time series are available. Superposed onto a general recession trend, we detected strong oscillations on shorter time scales and we showed that they are significantly correlated with fluctuations in winter precipitation rates and average summer temperatures. On the basis of these results, we constructed a simple lagged-linear empirical stochastic model that explained upto 66% of the variance of the snout fluctuation data. The model produces reliable out-of-sample predictions of the impact of climate variability on the glaciers of the western Alps and it can be used to estimate the average response of Alpine glaciers to different scenarios of climate change, provided the morphology of the individual glaciers does not change completely. Copyright © 2007 Royal Meteorological Society [source] A probabilistic zonal approach for swarm-inspired wildfire detection using sensor networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2008Chandrasekar Ramachandran Abstract In this paper, we propose a novel swarm-inspired system for detecting wildfires using sensor networks. There are three-fold concerns of this paper. The first is the speed of information propagation, the second is the accuracy of the information being propagated and the third is the reliability of the system over a long period of time. With these in mind, we develop a probabilistic model for focusing on responses for query requests in an accurate manner, similar to the assignment of probabilities of occurrence in a distributed database. We follow a data-centric approach where the system executes a swarm-inspired routing and aggregation algorithm. For effective management of the system, zones of reachability are formed which denote areas, which help the sensor nodes in local maintenance, and through an interaction of these zones, a globally robust system is obtained. The system generates various kinds of reports and is connected to disaster response stations. We simulate our proposed system in NS-2 for certain parameters, and more importantly in the presence of failures, to conclude that the system performs well for different scenarios and very well when an optimal zone radius is chosen. Copyright © 2008 John Wiley & Sons, Ltd. [source] Expedited forwarding end-to-end delay and jitter in DiffServINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 8 2008Hamada Alshaer Abstract The scheduling disciplines and active buffer management represent the main components employed in the differentiated services (DiffServ) data plane, which provide qualitative per-hop behaviors corresponding to the QoS required by supported traffic classes. In the first part of this paper, we compute the per-hop delay bound that should be guaranteed by the different multiservice scheduling disciplines, so that the end-to-end (e2e) delay required by expedited forwarding (EF) traffic can be guaranteed. Consequently, we derive the e2e delay bound of EF traffic served by priority queuing,weighted fair queuing (PQ,WFQ) at every hop along its routing path. Although real-time flows are principally offered EF service class, some simulations on DiffServ-enabled network show that these flows suffer from delay jitter and they are negatively impacted by lower priority traffic. In the second part of this paper, we clarify the passive impact of delay jitter on EF traffic, where EF flows are represented by renewal periodic ON,OFF flows, and the background (BG) flows are characterized by the Poisson process. We analyze through different scenarios the jitter effects of these BG flows on EF flow patterns when they are served by a single class scheduling discipline, such as first-input first-output, and a multiclass or multiservice scheduling discipline, such as static priority service discipline. As a result, we have found out that the EF per-hop behaviors (PHBs) configuration according to RFCs 2598 and 3246 (IETF RFC 2598, June 1999; RFC 3246, IETF, March 2002) cannot stand alone in guaranteeing the delay jitter required by EF flows. Therefore, playout buffers must be added to DiffServ-enabled networks for handling delay jitter problem that suffers from EF flows. Copyright © 2008 John Wiley & Sons, Ltd. [source] Closed-form expression for the BER of m-QAM-OFDM systems over time- and frequency-selective wireless channelsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 8 2006F. Castells Abstract The broadcast DVB-T system is an m-QAM-OFDM communication system that includes pilot-symbol-assisted modulation (PSAM) in order to enhance channel estimation at the receiver. This characteristic makes DVB-T suitable for a mobile reception, over time- and frequency-selective wireless channels. In this work, a closed-form expression for the BER as a function of the transmission system, channel model and the channel estimation strategy employed at the receiver is derived. In addition, adjacent channel interference due to Doppler effects is also considered. The results are focused on the DVB-T system under different scenarios. The channel estimation at the receiver has been shown to be very critical, and the impact of channel estimation errors on the BER is analysed in detail. Copyright © 2005 John Wiley & Sons, Ltd. [source] Evaluation of performance enhancing proxies in internet over satelliteINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2003Navid Ehsan Abstract Performance enhancing proxies (PEPs) are widely used to improve the performance of TCP over high delay-bandwidth product links and links with high error probability. In this paper we analyse the performance of using TCP connection splitting in combination with web caching via traces obtained from a commercial satellite system. We examine the resulting performance gain under different scenarios, including the effect of caching, congestion, random loss and file sizes. We show, via analysing our measurements, that the performance gain from using splitting is highly sensitive to random losses and the number of simultaneous connections, and that such sensitivity is alleviated by caching. On the other hand, the use of a splitting proxy enhances the value of web caching in that cache hits result in much more significant performance improvement over cache misses when TCP splitting is used. We also compare the performance of using different versions of HTTP in such a system. Copyright © 2003 John Wiley & Sons, Ltd. [source] Decision support for simulating the car park activity in an urban areaJOURNAL OF ADVANCED TRANSPORTATION, Issue 2 2009Jean-Marie Boussier Abstract Complexity of car park activity is reproduced from a concurrent execution of behaviour of various drivers. This paper presents a step in the development of a multimodal traffic simulator based on multi-agent paradigm and designed as a decision aid tool as well as a video game. The user-player has the opportunity to test different scenarios. We propose an approach for designing the decision-making rules and the learning mechanism for a car driver agent. For that, a panel of methods such as stated preference modelling, Design Of Experiments and data fusion is used. Initial behavioural models, based on similar preferences, are developed for specified categories. Each agent will adapt its behaviour after executing its learning process. Our approach can be used in order to optimize needs of road network users and those of people in charge of traffic regulation. A demonstrator has been developed to test parking policies in an urban area as well as changes of car park characteristics. [source] Selection of locations of knots for linear splines in random regression test-day modelsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2010J. Jamrozik Summary Using spline functions (segmented polynomials) in regression models requires the knowledge of the location of the knots. Knots are the points at which independent linear segments are connected. Optimal positions of knots for linear splines of different orders were determined in this study for different scenarios, using existing estimates of covariance functions and an optimization algorithm. The traits considered were test-day milk, fat and protein yields, and somatic cell score (SCS) in the first three lactations of Canadian Holsteins. Two ranges of days in milk (from 5 to 305 and from 5 to 365) were taken into account. In addition, four different populations of Holstein cows, from Australia, Canada, Italy and New Zealand, were examined with respect to first lactation (305 days) milk only. The estimates of genetic and permanent environmental covariance functions were based on single- and multiple-trait test-day models, with Legendre polynomials of order 4 as random regressions. A differential evolution algorithm was applied to find the best location of knots for splines of orders 4 to 7 and the criterion for optimization was the goodness-of-fit of the spline covariance function. Results indicated that the optimal position of knots for linear splines differed between genetic and permanent environmental effects, as well as between traits and lactations. Different populations also exhibited different patterns of optimal knot locations. With linear splines, different positions of knots should therefore be used for different effects and traits in random regression test-day models when analysing milk production traits. [source] Information theoretical measures to analyze trajectories in rational molecular designJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 16 2007K. Hamacher Abstract We develop a new methodology to analyze molecular dynamics trajectories and other time series data from simulation runs. This methodology is based on an information measure of the difference between distributions of various data extract from such simulations. The method is fast as it only involves the numerical integration/summation of the distributions in one dimension while avoiding sampling issues at the same time. The method is most suitable for applications in which different scenarios are to be compared, e.g. to guide rational molecular design. We show the power of the proposed method in an application of rational drug design by reduced model computations on the BH3 motif in the apoptosis inducing BCL2 protein family. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007 [source] Life-Cycle Assessment of Biosolids Processing OptionsJOURNAL OF INDUSTRIAL ECOLOGY, Issue 2 2001Gregory M. Peters Summary Biosolids, also known as sewage sludge, are reusable organic materials separated from sewage during treatment. They can be managed in a variety of ways. Different options for biosolids handling in Sydney, Australia, are compared in this study using life-cycle assessment. Two key comparisons are made: of system scenarios (scenario 1 is local dewatering and lime amendment; scenario 2 is a centralized drying system) and of technologies (thermal drying versus lime amendment). The environmental issues addressed are energy consumption, global warming potential (GWP), and human toxicity potential (HTP). Scenario 2 would consume 24% more energy than scenario 1. This is due to the additional electricity for pumping and particularly the petrochemical methane that supplements biogas in the drier. A centralized system using the same technologies as scenario 1 has approximately the same impacts. The GWP and HTP of the different scenarios do not differ significantly. The assessment of technology choices shows significant differences. The ample supply of endogenous biogas at North Head sewage treatment plant for the drying option allows reductions, relative to the lime-amendment option, of 68% in energy consumption, 45% in GWP, and 23% in HTP. Technology choices have more significant influence on the environmental profile of biosolids processing than does the choice of system configurations. Controlling variables for environmental improvement are the selection of biogas fuel, avoidance of coalsourced electrical energy, minimization of trucking distances, and raising the solids content of biosolids products. [source] The Upper Pleistocene to Holocene sediments on the Mediterranean island of Lampedusa (Italy)JOURNAL OF QUATERNARY SCIENCE, Issue 6 2004C. Giraudi Abstract The island of Lampedusa lies on the northern edge of the African continental shelf, but during some Quaternary marine lowstands it was joined to the African continent. The study and dating of the aeolian, alluvial, detrital sediments, calcareous crusts and speleothems have established that the climatic,environmental variations recorded on the island can be related chronologically to those known for northern Libya, Tunisia and the Italian peninsula. During the Last Glacial Maximum, phases of Saharan dust accumulation on Lampedusa occurred, and were coeval with dust accumulation in crater lakes and on high mountains in central-southern Italy, and with phases of glacial advance in the Apennines and in the Alps. During the late Holocene, accumulation of Saharan dust on Lampedusa occurred but there was little accumulation of dust on the northern side of the Mediterranean Sea. With the new data from Lampedusa, it is possible to envisage two different scenarios of atmospheric circulation relating to the Last Glacial Maximum and to the late Holocene. During the Last Glacial Maximum, southerly atmospheric circulation brought rainfall to the southern slopes of the Alps and to the Apennines. During the late Holocene, a prevalent westerly atmospheric circulation became established in the northern Mediterranean. Copyright © 2004 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||