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Cost Ratio (cost + ratio)
Selected AbstractsCompartmentalisation: flood consequence reduction by splitting up large polder areasJOURNAL OF FLOOD RISK MANAGEMENT, Issue 1 2010F. Klijn Abstract River and coastal floodplains are often protected by vast systems of connected embankments. In the Netherlands, about 55% of the country is protected in this way, by some 3600 km of primary defences. The protection level is probably the highest in the world, and annual mean flood risks are low. Nevertheless, the consequences of a major flood event might be unacceptable. This is a reason to consider whether and how the consequences of floods could be reduced in a cost-effective manner. Splitting up large polder areas into smaller portions, the so-called compartmentalisation, would reduce the area subject to flooding, and thus the economic damage, the number of people exposed and the fatality risk. We carried out a policy analysis for the national authorities in order to establish whether, where and under which conditions a further compartmentalisation of the country would be desirable. This paper gives some results, discusses our experiences in four case studies and finally focuses on the fundamental questions of assessment and the trade-off between better flood protection and the benefit/cost ratio of reducing consequences. [source] Optimal conservation planning for migratory animals: integrating demographic information across seasonsCONSERVATION LETTERS, Issue 3 2010Justin Sheehy Abstract Conservation strategies for migratory animals are typically based on ad-hoc or simple ranking methods and focus on a single period of the annual cycle. We use a density-dependent population model to examine one-time land purchase strategies for a migratory population with a breeding and wintering grounds. Under equal rates of habitat loss, we show that it is optimal to invest more, but never solely, in the habitat with the higher density dependence to habitat cost ratio. When there are two habitats that vary in quality within a season, the best strategy is to invest only in one habitat. Whether to purchase high- or low-quality habitat depends on the general life history of the species and the ratio of habitat quality to habitat cost. When carry-over effects are incorporated, it is almost always optimal to invest in high-quality habitat during the season that produces the carry-over effect. We apply this model to a threatened warbler population and show the optimal strategy is to purchase more breeding than wintering habitat despite the fact that breeding habitat is over ten times more expensive. Our model provides a framework for developing year-round conservation strategies for migratory animals and has important implications for long-term planning and management. [source] A cost analysis of ranked set sampling to estimate a population meanENVIRONMETRICS, Issue 3 2005Rebecca A. Buchanan Abstract Ranked set sampling (RSS) can be a useful environmental sampling method when measurement costs are high but ranking costs are low. RSS estimates of the population mean can have higher precision than estimates from a simple random sample (SRS) of the same size, leading to potentially lower sampling costs from RSS than from SRS for a given precision. However, RSS introduces ranking costs not present in SRS; these costs must be considered in determining whether RSS is cost effective. We use a simple cost model to determine the minimum ratio of measurement to ranking costs (cost ratio) necessary in order for RSS to be as cost effective as SRS for data from the normal, exponential, and lognormal distributions. We consider both equal and unequal RSS allocations and two types of estimators of the mean: the typical distribution-free (DF) estimator and the best linear unbiased estimator (BLUE). The minimum cost ratio necessary for RSS to be as cost effective as SRS depends on the underlying distribution of the data, as well as the allocation and type of estimator used. Most minimum necessary cost ratios are in the range of 1,6, and are lower for BLUEs than for DF estimators. The higher the prior knowledge of the distribution underlying the data, the lower the minimum necessary cost ratio and the more attractive RSS is over SRS. Copyright © 2005 John Wiley & Sons, Ltd. [source] Nutrient constraints to tropical agroecosystem productivity in long-term degrading soilsGLOBAL CHANGE BIOLOGY, Issue 12 2008SOLOMON NGOZE Abstract Soil degradation is one of the most serious threats to sustainable crop production in many tropical agroecosystems where extensification rather than intensification of agriculture has occurred. In the highlands of western Kenya, we investigated soil nitrogen (N) and phosphorus (P) constraints to maize productivity across a cultivation chronosequence in which land-use history ranged from recent conversion from primary forest to 100 years in continuous cropping. Nutrient treatments included a range of N and P fertilizer rates applied separately and in combination. Maize productivity without fertilizer was used as a proxy measure for indigenous soil fertility (ISF). Soil pools of mineral nitrogen, strongly bound P and plant-available P decreased by 82%, 31% and 36%, and P adsorption capacity increased by 51% after 100 years of continuous cultivation. For the long rainy season (LR), grain yield without fertilizer declined rapidly as cultivation age increased from 0 to 25 years and then gradually declined to a yield of 1.6 Mg ha,1, which was maintained as time under cultivation increased from 60 to 100 years. LR grain yield in the old conversions was only 24% of the average young conversion grain yield (6.4 Mg ha,1). Application of either N or P alone significantly increased grain yield in both the LR and short rainy (SR) seasons, but only application of 120 kg N ha,1 on the old conversion increased yield by >1 Mg ha,1. In both SR and LR, there was a greater average yield increment response to N and P when applied together (ranging from 1 to 3.8 Mg ha,1 for the LR), with the greatest responses on the old conversions. The benefit,cost ratio (BCR) for applying 120 kg N ha,1 alone was <1 except on the old conversions, while BCRs were>1 for applying 25 kg P ha,1 alone at all levels of conversion for both seasons. Application of both N (120 kg N ha,1) and P (25 kg P ha,1) on the old conversions resulted in the greatest BCRs. This study clearly indicates that maize productivity responses to N and P fertilizer are significantly affected by the age of cultivation and its influence on ISF, but that loss of productivity can be restored rapidly when these limiting nutrients are applied. Management strategies should consider ISF and economic factors to determine optimal N and P input requirements for achieving and sustaining profitable crop production on degraded soils. [source] A decision support tool for irrigation infrastructure investments,IRRIGATION AND DRAINAGE, Issue 4 2010Shahbaz Khan outil d'aide à la décision; gestion de l'eau; investissements saisonniers et à long terme; optimisation; simulation; analyse coûts-avantages; ensemble de l'exploitation; négociation de l'eau; économie d'eau Abstract Increasing water scarcity, climate change and pressure to provide water for environmental flows urge irrigators to be more efficient. In Australia, ongoing water reforms and most recently the National Water Security Plan offer incentives to irrigators to adjust their farming practices by adopting water-saving irrigation infrastructures to match soil, crop and climatic conditions. WaterWorks is a decision support tool to facilitate irrigators to make long- and short-term irrigation infrastructure investment decisions at the farm level. It helps irrigators to improve the economic efficiency, water use efficiency and environmental performance of their farm businesses. WaterWorks has been tested, validated and accepted by the irrigation community and researchers in NSW, Australia. The interface of WaterWorks is user-friendly and flexible. The simulation and optimisation module in WaterWorks provides an opportunity to evaluate infrastructure investment decisions to suit their seasonal or long-term water availability. The sensitivity analysis allows substantiation of the impact of major variables. Net present value, internal rate of return, benefit,cost ratio and payback period are used to analyse the costs and benefits of modern irrigation technology. Application of WaterWorks using a whole farm-level case study indicates its effectiveness in making long- and short-term investment decisions. WaterWorks can be easily integrated into commercial software such as spreadsheets, GIS, real-time data acquisition and control systems to further enhance its usability. WaterWorks can also be used in regional development planning. Copyright © 2009 John Wiley & Sons, Ltd. L'augmentation de la rareté de l'eau, le changement climatique et la pression pour fournir de l'eau pour l'environnement incitent les irrigants à être plus efficaces. En Australie les réformes en cours sur l'eau, et plus récemment le Plan National de Sécurité de l'Eau, incitent les irrigants à ajuster leurs pratiques agricoles par l'adoption d'infrastructures d'irrigation économisant l'eau pour s'adapter aux conditions de sols, de cultures et de climat. WaterWorks est un outil d'aide à la décision pour faciliter les décisions d'investissement à long terme et court terme au niveau de l'exploitation. Il aide les irrigants à améliorer l'efficacité économique, l'efficacité de l'utilisation de l'eau et la performance environnementale de leurs exploitations agricoles. Le WaterWorks a été testé, validé et accepté par la communauté de l'irrigation dans le New South Wales, Australie. L'interface de WaterWorks est convivial et flexible. Le module de simulation et d'optimisation dans WaterWorks permet d'évaluer les décisions d'investissement en fonction de la disponibilité en eau saisonnière ou à long terme. L'analyse de sensibilité permet d'étayer l'impact des principales variables. La valeur actuelle nette, le taux de rendement interne, le ratio coûts-avantages et la période de récupération sont utilisés pour analyser les coûts et les avantages des technologies modernes d'irrigation. L'application de WaterWorks à une étude de cas complète au niveau de l'exploitation montre son efficacité pour les décisions d'investissement à long terme et court terme. Le WaterWorks peut être facilement intégré dans des logiciels commerciaux tels que les tableurs, les SIG, des systèmes d'acquisition de données en temps réel et de contrôle afin d'améliorer sa convivialité. Le WaterWorks peut également être utilisé pour la planification du développement régional. Copyright © 2009 John Wiley & Sons, Ltd. [source] Uncertainty, Real Options, and Cost Behavior: Evidence from Washington State HospitalsJOURNAL OF ACCOUNTING RESEARCH, Issue 5 2005SANJAY KALLAPUR ABSTRACT This study tests an implication of the real-options theory of investment, that uncertainty leads firms to prefer technologies with low fixed and high variable costs. In 1983, a change in Medicare reimbursement increased the uncertainty of revenues for hospitals. Using a sample of 831 departments in 59 Washington State hospitals over the 1977,1994 period, we find that the ratio of variable to total costs increased after 1983. This increase is not attributable to a gradual increase in the ratio over time: We estimate a significant increase after 1983 even after controlling for a time trend. Further, we find a greater increase in the variable-to-total cost ratio for hospitals that had higher percentages of Medicare patients, increasing our confidence in the conclusion that the change in cost behavior is attributable to Medicare's change in reimbursement. [source] Physiological performance of largemouth bass related to local adaptation and interstock hybridization: implications for conservation and managementJOURNAL OF FISH BIOLOGY, Issue 2001S. J. Cooke Four genetically distinct stocks of age 2+ years largemouth bass Micropterus salmoides were produced using adults collected from two regions in the upper midwest (central Illinois, IL and south-eastern Wisconsin, WI, U.S.A.). Two pure stocks (IL × IL and WI × WI), as well as both of their reciprocal F1 interstock hybrids (IL × WI and WI × IL) were produced in research ponds in Champaign, IL. In general, swimming performance, routine oxygen consumption and activity were highest at 18 × C, intermediate at 12 × C, and lowest at 6. C for all stocks. However, performance indicators varied among stocks at each of the temperatures. The pure Illinois stock (IL × IL) had the lowest activity: cost ratio at 18 × C and the highest at 6_ C (based upon swimming strength, routine activity rates and routine metabolic rates). The opposite pattern was observed for the other pure stock (WI × WI). Although differences were less distinct at lower temperatures, the two pure stocks (IL × IL and WI × WI) outperformed both interstock hybrids. These results indicate that not only do non-native stocks appear to have reduced performance relative to locally adapted stocks, but also that interstock hybrids exhibit performance impairments, not hybrid vigour. [source] Terrestrial carnivores and human food production: impact and managementMAMMAL REVIEW, Issue 2-3 2008PHILIP J. BAKER ABSTRACT 1The production of food for human consumption has led to an historical and global conflict with terrestrial carnivores, which in turn has resulted in the extinction or extirpation of many species, although some have benefited. At present, carnivores affect food production by: (i) killing human producers; killing and/or eating (ii) fish/shellfish; (iii) game/wildfowl; (iv) livestock; (v) damaging crops; (vi) transmitting diseases; and (vii) through trophic interactions with other species in agricultural landscapes. Conversely, carnivores can themselves be a source of dietary protein (bushmeat). 2Globally, the major areas of conflict are predation on livestock and the transmission of rabies. At a broad scale, livestock predation is a customary problem where predators are present and has been quantified for a broad range of carnivore species, although the veracity of these estimates is equivocal. Typically, but not always, losses are small relative to the numbers held, but can be a significant proportion of total livestock mortality. Losses experienced by producers are often highly variable, indicating that factors such as husbandry practices and predator behaviour may significantly affect the relative vulnerability of properties in the wider landscape. Within livestock herds, juvenile animals are particularly vulnerable. 3Proactive and reactive culling are widely practised as a means to limit predation on livestock and game. Historic changes in species' distributions and abundance illustrate that culling programmes can be very effective at reducing predator density, although such substantive impacts are generally considered undesirable for native predators. However, despite their prevalence, the effectiveness, efficiency and the benefit:cost ratio of culling programmes have been poorly studied. 4A wide range of non-lethal methods to limit predation has been studied. However, many of these have their practical limitations and are unlikely to be widely applicable. 5Lethal approaches are likely to dominate the management of terrestrial carnivores for the foreseeable future, but animal welfare considerations are increasingly likely to influence management strategies. The adoption of non-lethal approaches will depend upon proof of their effectiveness and the willingness of stakeholders to implement them, and, in some cases, appropriate licensing and legislation. 6Overall, it is apparent that we still understand relatively little about the importance of factors affecting predation on livestock and how to manage this conflict effectively. We consider the following avenues of research to be essential: (i) quantified assessments of the loss of viable livestock; (ii) landscape-level studies of contiguous properties to quantify losses associated with variables such as different husbandry practices; (iii) replicated experimental manipulations to identify the relative benefit of particular management practices, incorporating (iv) techniques to identify individual predators killing stock; and (v) economic analyses of different management approaches to quantify optimal production strategies. [source] The option to change the use of a property when future property values and construction costs are uncertainMANAGERIAL AND DECISION ECONOMICS, Issue 7 2001Åke Gunnelin This paper models the decision to change the use of a property when its value in the current use and the new use, as well as construction costs, are uncertain. In the case of development of vacant land, when cash flows and construction costs are lognormally distributed, the development of the property optimally takes place when the ratio of benefit to cost of development reaches some fixed level. In the redevelopment case, the timing problem is found to be more complex, as the cost of exercising the conversion option consists of two parts, the construction costs and the surrendered value of the property in the current use, which may evolve differently over time. In this case, optimal redevelopment will take place for different benefit,cost ratios, depending on the relative sizes of the property values in the different uses and the construction costs. Also, for a given current benefit,cost ratio, the option value will vary significantly, depending on the relative size of the state variables. Copyright © 2001 John Wiley & Sons, Ltd. [source] Optimal Robust Two-Stage Designs for Genome-Wide Association StudiesANNALS OF HUMAN GENETICS, Issue 6 2009Thuy Trang Nguyen Summary Optimal robust two-stage designs for genome-wide association studies are proposed using the maximum of the recessive, additive and dominant linear trend test statistics. These designs combine cost-saving two-stage genotyping with robustness against misspecification of the genetic model and are much more efficient than designs based on a single model specific test statistic in detecting multiple loci with different modes of inheritance. For given power of 90%, typical cost savings of 34% can be realised by increasing the total sample size by about 13% but genotyping only about half of the sample for the full marker set in the first stage and carrying forward about 0.06% of the markers to the second stage analysis. We also present robust two-stage designs providing optimal allocation of a limited budget for pre-existing samples. If a sample is available which would yield a power of 90% when fully genotyped, genotyping only half of the sample due to a limited budget will typically cause a loss of power of more than 55%. Using an optimal two-stage approach in the same sample under the same budget restrictions will limit the loss of power to less than 10%. In general, the optimal proportion of markers to be followed up in the second stage strongly depends on the cost ratio for chips and individual genotyping, while the design parameters of the optimal designs (total sample size, first stage proportion, first and second stage significance limit) do not much depend on the genetic model assumptions. [source] Tropical spiny lobster (Panulirus ornatus) farming in Vietnam , bioeconomics and perceived constraints to developmentAQUACULTURE RESEARCH, Issue 10 2010Elizabeth H Petersen Abstract This paper presents bioeconomic data on lobster farming in Vietnam, and perceived constraints to the development of the industry. The farms were found to be profitable, with an average benefit cost ratio of 1.44 and an average net revenue of 262 million VND year,1 (or just under US$15 000 year,1). Investment in the enterprise is high compared with other enterprises in the region. However, disease has the potential to devastate lobster crops and there is little information available to lobster farmers about disease prevention and management. Hence, the lobster enterprise is a high-risk high-return industry. The predominant perceived constraints to the development of lobster operations include water quality and temperature issues, insufficient access to credit, good-quality affordable feed and accurate information about technology improvements in lobster farming. It seems that improving the livelihood of lobster farmers in Vietnam is dependent on reducing their dependence on wild stocks for seed and feed, improving access to credit and improving technical and market information flows. Such improvements are likely to lead to higher profitability, given high export demand and hence sustained high prices for their lobster product. [source] Modelling selective breeding in protandrous, batch-reared Asian sea bass (Lates calcarifer, Bloch) using walkback selectionAQUACULTURE RESEARCH, Issue 10 2010Nicholas Andrew Robinson Abstract A bioeconomic simulation model for Lates calcarifer predicted that a strategy involving crossing current generation males with previous generation females would be a practical, effective and profitable way of dealing with protandry when batch rearing for selective breeding to improve the growth rate. The strategy allowed earlier initialization and more frequent ongoing rounds of selection, and resulted in a 16,19% higher overall response, than an alternative where each generation's males were crossed with the same generation's females. The strategy also yielded the highest short-term benefit,cost ratio (13:1 versus 7:1 after 8 years of selective breeding) and the highest short- and long-term value for participants in a breeding cooperative (a net present value of AU$28 million and an internal rate of return of 144% over 10 years), due to higher yields per fixed costs of production per unit area and due to savings in feed costs per kilogram of production. Breeding facilities of scale producing 50 full-sibling families per generation were found to be more profitable than those producing 100 families. [source] Performance evaluation of concurrent rice,fish,prawn culture with and without cull harvestingAQUACULTURE RESEARCH, Issue 9 2010Rajeeb K Mohanty Abstract This study was carried out in farmers' fields for three experimental culture cycles to evaluate the performance of rice,fish,prawn culture. The treatments carried out were deepwater rice mono-cropping (R), and rice,fish,prawn culture with cull harvesting (R,FC) and without cull harvesting (R,F). Water pH and total alkalinity were significantly higher (P<0.05) in R,FC than in R,F, while the concentrations of total suspended solids, plankton and chlorophyll a were higher in R,F. Cull harvesting in R,FC had no marked influence on the concentrations of dissolved oxygen, NH4+, nitrite, nitrate and phosphate compared with the R,F treatment. The significantly higher fish and prawn yields (P<0.05) and species-wise faster individual growth performance in R,FC than in R,F were probably due to periodic cull harvesting, which minimized the competition for food and space as well as physiological stress at reduced density. The paddy yield and percentage increase in paddy yield over rice mono-crop was significantly higher (P<0.05) in R,FC (25%), followed by R,F (16.9%), probably due to lower chlorophyll a (36.7 mg m,3) and plankton density (1.4 × 104 L,1), which minimized the competition for nutrients with rice plants. The highest rice equivalent yield (38.5), output value,cultivation cost ratio (1.56) and enhanced net return (28%) in deepwater rice,fish culture were recorded when cull harvesting was practiced. [source] Testing options for the commercialization of abalone selective breeding using bioeconomic simulation modellingAQUACULTURE RESEARCH, Issue 9 2010Nick Robinson Abstract The genetic response and economic benefit from alternative breeding programme designs for blacklip and greenlip abalone (Haliotis rubra and Haliotis laevigata, respectively) were evaluated using a computer simulation model. Two selection criteria were investigated, one used family breeding values for liability to disease challenge test infection and the other used a direct selection of the best performing individuals across families for growth rate. Five scales of breeding programme were tested and the model predicted that if growth rate is the only selection criterion, breeding programmes of a scale using 150 families of each species each generation would result in 12,13% genetic improvement in initial generations and have the greatest beneficial economic impact on the Australian abalone industry of the options tested. The model predicts an average discounted benefit,cost ratio of 48:1, total added discounted benefit of AU$4.90 for each kilogram of abalone produced and nominal economic effect on operating income of over AU$16 million per year after 10 years. If disease resistance is the only selective breeding criterion, 100 families of each species would result in the highest benefit,cost ratio of the options tested, although some genetic gain would need to be sacrificed to reduce inbreeding to acceptable levels in this scenario. A strategy for a stand-alone abalone selective breeding cooperative was also modelled. For a farm of current tank area yielding 100 t year,1, participation is expected to yield over AU$0.7 million in discounted total added production value and annual discounted returns of over AU$0.4 million per annum by year 10. [source] Effects of all-male, mixed-sex and all-female freshwater prawn in polyculture with major carps and molas in the fallow rice fieldsAQUACULTURE RESEARCH, Issue 1 2009Mrityunjoy Kunda Abstract This study was conducted to evaluate the effects of all-male, mixed-sex and all-female freshwater prawn (Macrobrachium rosenbergii) in a polyculture with major carps (Catla catla and Labeo rohita) and self-recruiting small fish molas (Amblypharyngodon mola) in the fallow rice fields of Bangladesh. There were three treatments with three replicates. All ponds were stocked with carps and molas plus either all-male prawns (treatment MP), mixed-sex prawns (MFP) or all-female prawns (FP). Prawn, mola, catla and rohu were stocked 20 000, 20 000, 1750 and 750 ha,1, respectively, in all treatments. The prawns were fed twice daily, starting at 8% body weight and gradually reduced to 3% body weight. The fish were fed in the morning with mustard oil cake and rice bran (1:2 ratios) at 3% body weight. Significantly higher production of prawns (697 kg ha,1) was obtained in treatment MP, which yielded 34.7% and 56.2% more production than MFP and FP respectively. Significantly higher total production of 1620 kg ha,1 and a higher benefit,cost ratio of 2.10:1 were also obtained in treatment MP. It can be concluded that an all-male prawn culture is economically more viable than all-female and mixed-sex prawn cultures, along with other fish like major carps and the nutrient-dense molas in the polyculture. [source] Effects of including catla and tilapia in a freshwater prawn,mola polyculture in a rotational rice,fish culture systemsAQUACULTURE RESEARCH, Issue 9 2009Mrityunjoy Kunda Abstract An on-farm trial was carried out from February to June 2006 to evaluate the growth and production performance of catla (Catla catla) and tilapia (Oreochromis niloticus) with freshwater prawn (Macrobrachium rosenbergii) and mola (Amblypharyngodon mola) in farmer's rice fields. In all treatments, 20 000 mola ha,1 and 20 000 prawn ha,1 were stocked. Besides, stocking included 2500 catla ha,1 in treatment-I, 2500 tilapia ha,1 in treatment-II and catla and tilapia at 1250 ha,1 each in treatment-III . Prawns were fed in the evening with pellets at a feeding rate of 3,8% body weight (initially 8% and gradually decreased to 3%). Catla and tilapia were fed in the morning with a paste of mustard oil cake and rice bran at a feeding rate of 3% body weight. Significantly higher combined production of fish and prawn observed was 2142 kg ha,1 in treatment-I. The benefit:cost ratio was found to be significantly higher in treatment-I than in treatment-II and there were no differences between treatments I and III. From the production and economic point of view, treatment-I was found to be the best proposition for the rotational rice,fish culture systems. [source] Stochastic scheduling problem with varying weight for each jobASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010Manzhan Gu Abstract This paper studies the preemptive stochastic online scheduling problem, which is a simple combination of online and stochastic scheduling. The processing times of jobs are assumed to be subject to independent probability distributions, and we assume that jobs arrive overtime, which means there is no knowledge about the jobs that arrive in the future. We particularly consider the preemptive setting where a job is allowed to be interrupted during its processing. The weight (holding cost ratio) associated with each job may change during its processing, and the objective is to minimize the expected value of total holding cost for all jobs. For the single and m identical machine problems, we propose scheduling policies, SPGS [semi-preemptive Gittins Index Priority Policy (GIPP) on single machine] and SPGI (semi-preemptive GIPP on identical machines), respectively, both of which are proved to be constant-factor approximation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Impact of research investment on Cassava production technologies in India,AUSTRALIAN JOURNAL OF AGRICULTURAL & RESOURCE ECONOMICS, Issue 3 2009Tavva Srinivas The present study was an ex-post assessment done to validate past funding on cassava research, based on economic surplus approach. Though cassava was introduced as a food crop in Kerala, India from Brazil, it has changed its status to commercial crop at present in Tamil Nadu and Andhra Pradesh states. This was made possible due to intensive research and development efforts of different R&D organizations. Cassava technologies developed enabled in sustaining the crop in the country with the world's highest productivity. All the cassava production technologies considered in the study resulted in an economic surplus of Rs.3585.87 million in the target domain covering Kerala, Tamil Nadu and Andhra Pradesh. Consumers and producers benefited to the tune of Rs.2090.64 million and Rs.1495.23 million respectively. Net present value of economic gains was estimated to be Rs.3548.76 million. Present value of research investment on cassava production technologies was Rs.37.11 million resulting in benefit cost ratio of 96.63:1 with a high internal rate of return of 104 per cent. Thus the study indicated that the research investments incurred on cassava production technologies development was highly economical and provided evidence to the policy makers that supporting the research investment on underground, under exploited tropical root crops like cassava is an economically viable proposition. [source] Post-earthquake bridge repair cost and repair time estimation methodologyEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2010Kevin R. Mackie Abstract While structural engineers have traditionally focused on individual components (bridges, for example) of transportation networks for design, retrofit, and analysis, it has become increasingly apparent that the economic costs to society after extreme earthquake events are caused at least as much from indirect costs as direct costs due to individual structures. This paper describes an improved methodology for developing probabilistic estimates of repair costs and repair times that can be used for evaluating the performance of new bridge design options and existing bridges in preparation for the next major earthquake. The proposed approach in this paper is an improvement on previous bridge loss modeling studies,it is based on the local linearization of the dependence between repair quantities and damage states so that the resulting model follows a linear relationship between damage states and repair points. The methodology uses the concept of performance groups (PGs) that account for damage and repair of individual bridge components and subassemblies. The method is validated using two simple examples that compare the proposed method to simulation and previous methods based on loss models using a power,law relationship between repair quantities and damage. In addition, an illustration of the method is provided for a complete study on the performance of a common five-span overpass bridge structure in California. Intensity-dependent repair cost ratios (RCRs) and repair times are calculated using the proposed approach, as well as plots that show the disaggregation of repair cost by repair quantity and by PG. This provides the decision maker with a higher fidelity of data when evaluating the contribution of different bridge components to the performance of the bridge system, where performance is evaluated in terms of repair costs and repair times rather than traditional engineering quantities such as displacements and stresses. Copyright © 2009 John Wiley & Sons, Ltd. [source] Road pricing: lessons from LondonECONOMIC POLICY, Issue 46 2006Georgina Santos SUMMARY Road pricing LESSONS FROM LONDON This paper assesses the original London Congestion Charging Scheme (LCCS) and its impacts, and it simulates the proposed extension which will include most of Kensington and Chelsea. It also touches upon the political economy of the congestion charge and the increase of the charge from £5 to £8 per day. The possibility of transferring the experience to Paris, Rome and New York is also discussed. The LCCS has had positive impacts. This was despite the considerable political influences on the charge level and location. It is difficult to assess the impacts of the increase of the charge from £5 to £8, which took place in July 2005, because no data have yet been released by Transport for London. The proposed extension of the charging zone does not seem to be an efficient change on economic grounds, at least for the specific boundaries, method of charging and level of charging that is currently planned. Our benefit cost ratios computed under different assumptions of costs and benefits are all below unity. Overall, the experience shows that simple methods of congestion charging, though in no way resembling first-best Pigouvian taxes, can do a remarkably good job of creating benefits from the reduction of congestion. Nevertheless, the magnitude of these benefits can be highly sensitive to the details of the scheme, which therefore need to be developed with great care. , Georgina Santos and Gordon Fraser [source] A cost analysis of ranked set sampling to estimate a population meanENVIRONMETRICS, Issue 3 2005Rebecca A. Buchanan Abstract Ranked set sampling (RSS) can be a useful environmental sampling method when measurement costs are high but ranking costs are low. RSS estimates of the population mean can have higher precision than estimates from a simple random sample (SRS) of the same size, leading to potentially lower sampling costs from RSS than from SRS for a given precision. However, RSS introduces ranking costs not present in SRS; these costs must be considered in determining whether RSS is cost effective. We use a simple cost model to determine the minimum ratio of measurement to ranking costs (cost ratio) necessary in order for RSS to be as cost effective as SRS for data from the normal, exponential, and lognormal distributions. We consider both equal and unequal RSS allocations and two types of estimators of the mean: the typical distribution-free (DF) estimator and the best linear unbiased estimator (BLUE). The minimum cost ratio necessary for RSS to be as cost effective as SRS depends on the underlying distribution of the data, as well as the allocation and type of estimator used. Most minimum necessary cost ratios are in the range of 1,6, and are lower for BLUEs than for DF estimators. The higher the prior knowledge of the distribution underlying the data, the lower the minimum necessary cost ratio and the more attractive RSS is over SRS. Copyright © 2005 John Wiley & Sons, Ltd. [source] Thermoeconomic analysis of household refrigeratorsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2007Arif Hepbasli Abstract This study deals with thermoeconomic analysis of household refrigerators for providing useful insights into the relations between thermodynamics and economics. In the analysis, the EXCEM method based on the quantities exergy, cost, energy and mass is applied to a household refrigerator using the refrigerant R134a. The performance evaluation of the refrigerator is conducted in terms of exergoeconomic aspects based on the various reference state temperatures ranging from 0 to 20°C. The exergy destructions in each of the components of the overall system are determined for average values of experimentally measured parameters. Exergy efficiencies of the system components are determined to assess their performances and to elucidate potentials for improvement. Thermodynamic loss rate-to-capital cost ratios for each components of the refrigerator are investigated. Correlations are developed to estimate exergy efficiencies and ratios of exergy loss rate-to-capital cost as a function of reference (dead) state temperature. The ratios of exergy loss rates to capital cost values are obtained to vary from 2.949 × 10,4 to 3.468 × 10,4 kW US$,1. The exergy efficiency values are also found to range from 13.69 to 28.00% and 58.15 to 68.88% on the basis of net rational efficiency and product/fuel at the reference state temperatures considered, respectively. It is expected that the results obtained will be useful to those involved in the development of analysis and design methodologies that integrate thermodynamics and economics. Copyright © 2006 John Wiley & Sons, Ltd. [source] Measuring the effectiveness of U.S. rice export promotion programsAGRIBUSINESS : AN INTERNATIONAL JOURNAL, Issue 2 2009Pimbucha Rusmevichientong Three issues are examined relating to U.S. rice export promotion. First, the responsiveness of U.S. rice export demand with respect to U.S. rice export promotion is measured to determine the quantity impacts of these programs. Second, the overall effectiveness of the programs is examined in terms of whether the benefits exceed the cost. Finally, the optimality of U.S. rice export promotion in terms of expenditure levels is investigated. A double logarithmic econometric export demand equation is estimated to compute the export promotion elasticity while controlling for other demand determinants such as own price, the export price of competing countries, incomes, and exchange rates. Average benefit,cost ratios are computed for U.S. rice export promotion based on a range of excess supply own-price elasticities to compute the effectiveness of the programs. Finally, a marginal simulation analysis is conducted to explore the optimality of the investment in rice export promotion. [JEL Codes: Q17, Q18, Q13]. © 2009 Wiley Periodicals, Inc. [source] The option to change the use of a property when future property values and construction costs are uncertainMANAGERIAL AND DECISION ECONOMICS, Issue 7 2001Åke Gunnelin This paper models the decision to change the use of a property when its value in the current use and the new use, as well as construction costs, are uncertain. In the case of development of vacant land, when cash flows and construction costs are lognormally distributed, the development of the property optimally takes place when the ratio of benefit to cost of development reaches some fixed level. In the redevelopment case, the timing problem is found to be more complex, as the cost of exercising the conversion option consists of two parts, the construction costs and the surrendered value of the property in the current use, which may evolve differently over time. In this case, optimal redevelopment will take place for different benefit,cost ratios, depending on the relative sizes of the property values in the different uses and the construction costs. Also, for a given current benefit,cost ratio, the option value will vary significantly, depending on the relative size of the state variables. Copyright © 2001 John Wiley & Sons, Ltd. [source] A combined approach to the phylogeny of Cephalopoda (Mollusca)CLADISTICS, Issue 5 2004A. R. Lindgren Cephalopoda represents a highly diverse group of molluscs, ranging in habitat from coastal regions to deep benthic waters. While cephalopods remain at the forefront of modern biology, in providing insight into fields such as neurobiology and population genetics, little is known about the relationships within the group. This study provides a comprehensive phylogenetic analysis of Cephalopoda (Mollusca) using a combination of molecular and morphological data. Four loci (three nuclear 18S rRNA, fragments of 28S rRNA and histone H3 and one mitochondrial cytochrome c oxidase subunit I) were combined with 101 morphological characters to test the relationships of 60 species of cephalopods, with emphasis within Decabrachia (squids and cuttlefishes). Individual and combined data sets were analyzed using the direct optimization method, with parsimony as the optimality criterion. Analyses were repeated for 12 different parameter sets accounting for a range of indel/change and transversion/transition cost ratios. Most analyses support the monophyly of Cephalopoda, Nautiloidea, Coleoidea and Decabrachia, however, the monophyly of Octobrachia was refuted due to the lack of support for a Cirroctopoda + Octopoda group. When analyzing all molecular evidence in combination and for total evidence analyses, Vampyromorpha formed the sister group to Decabrachia under the majority of parameters, while morphological data and some individual data sets supported a sister relationship between Vampyromorpha and Octobrachia. Within Decabrachia, a relationship between the sepioids Idiosepiida, Sepiida, Sepiolida and the teuthid Loliginidae was supported. Spirulida fell within the teuthid group in most analyses, further rendering Teuthida paraphyletic. Relationships within Decabrachia and specifically Oegopsida were found to be highly parameter-dependent. © The Willi Hennig Society 2004. [source] Four-Year Cost-Utility Analyses of Sealed and Nonsealed First Permanent Molars in Iowa Medicaid-Enrolled ChildrenJOURNAL OF PUBLIC HEALTH DENTISTRY, Issue 4 2007Patita Bhuridej DDS Abstract Objectives: Dental sealants, by their ability to prevent caries and maintain teeth in better health, have some inherent utility to individuals, programs, or society. This study assessed the 4-year incremental cost utility of sealing first permanent molars of 6-year-old Iowa Medicaid enrollees from a societal perspective and identified the group of teeth or children in whom sealants are most cost effective. Methods: Dental services for first permanent molars were assessed using claims and encounter data for a group of continuously enrolled Medicaid enrollees who turned 6 between 1996 and 1999. Previously published utilities were used to weight the different health states. The weighted sum of outcomes [Quality-Adjusted Tooth-Years (QATYs)] was the measure of effectiveness. Costs and QATYs were discounted to the time of the child's sixth birthday. Results: For all first molars, the cost of treatment associated with sealed teeth was higher but the utility was also slightly higher over the 4-year period. The relative incremental cost per 0.19 QATY ratio [changing the health state from a restored tooth (utility=0.81) to a nonrestored tooth (utility =1)] by sealing the molar ranged from $36.7 to $83.5 per 0.19 QATY. The incremental cost/QATY ratio was lower for sealing lower utilizers and for mandibular versus maxillary molars. Conclusions: Sealants improved overall utility of first permanent molars after 4 years. The 4-year cost/QATY ratio of sealing the first permanent molar varied by arch and type of utilizers. Sealing first permanent molars in lower dental utilizers is the most cost-effective approach for prioritizing limited resources. [source] What is the role of tests of lung function in the management of infants with lung disease?PEDIATRIC PULMONOLOGY, Issue 1 2003S. Godfrey MD This review considers whether there is a role for lung function tests in the clinical management of infants with lung disease. The purpose of testing lung function in older subjects, the tests available for infants, and the practical problems of testing lung function in infants are considered. After reviewing all the facts, we suggest that there are four situations in which lung function testing should be recommended for infants, as follows: 1) the infant who presents with unexplained tachypnea, hypoxia, cough, or respiratory distress in whom a definitive diagnosis is not apparent from physical examination and other, less difficult investigations; 2) the infant with severe, continuous, chronic obstructive lung disease who does not respond to an adequate clinical trial of combined corticosteroid and bronchodilator therapy; 3) the infant with known respiratory disease of uncertain severity in whom there is need to justify management decisions; and 4) research and development. A review of 62 recent publications to determine how lung function tests are being used at the present time showed that they are being used overwhelmingly for research. The role of lung function testing in the clinical management of infants has not been established, and research is needed to clarify this situation. We suggest that such studies should explore the role of lung function tests in infants with specific symptoms, signs, or diagnoses, taking into account information from other types of investigation and the cost/benefit/risk ratios. Pediatr Pulmonol. 2003; 36:1,9. © 2003 Wiley-Liss, Inc. [source] The Gauss-Seidel fast affine projection algorithm for multichannel active noise control and sound reproduction systemsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 2-3 2005Martin Bouchard Abstract In the field of adaptive filtering, the fast implementations of affine projection algorithms are known to provide a good tradeoff between convergence speed and computational complexity. Such algorithms have recently been published for multichannel active noise control systems. Previous work reported that these algorithms can outperform more complex recursive least-squares algorithms when noisy plant models are used in active noise control systems. This paper proposes a new fast affine projection algorithm for multichannel active noise control or sound reproduction systems, based on the Gauss,Seidel solving scheme. The proposed algorithm has a lower complexity than the previously published algorithms, with the same convergence speed and the same good performance with noisy plant models, and a potential for better numerical stability. It provides the best performance/cost ratio. Details of the algorithm and its complexity are presented in the paper, with simulation results to validate its performance. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||