708 research outputs found

    Socioeconomic Factors and Water Quality in California

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    We investigate the relationships between water quality and socioeconomic factors in California at the county level for the years 1993 to 2006 using 24 water quality indicators coming from seven different types of water bodies. We estimate these relationships using three classes of models: the traditional per capita income-pollution level - Environmental Kuznets Curve (EKC) - specifications, a more inclusive model containing main socioeconomic variables such as agricultural intensity, land use, ethnic composition, population density and educational attainment, and a model that includes the socioeconomic variables while accounting for spatial correlations too. For most water quality indicators, we do not find support for EKC specifications. For pollutants like phosphorus and total suspended solids, the level of agricultural activity is a significant determinant of water quality in California, but for other surface water pollutants commonly considered agricultural pollutants, such as ammonia and nitrate, the level of agricultural activity is not statistically significant. We find that education, ethnic composition, age structure, land use, population density, and water area are all significantly correlated with various indicators of water quality.Water Quality Indicators, Socioeconomic Variables, EKC, Agriculture, Industry

    A PORTFOLIO OF NUTRIENTS: SOIL AND SUSTAINABILITY

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    This paper develops a basic dynamic economic model that can be used for theoretical and numerical analysis of optimal soil management practices. A dynamic biophysical/economic optimal control model is developed in a multi-disciplinary framework, treating soil as a multi-pool portfolio of a particular limiting mobile nutrient (e.g. nitrogen). This specification allows for fertilizer to directly enter the active pool, while tillage initially affects the decadal pool, reflecting the realities of agricultural production. We examine the properties of the steady-state and the time paths of the optimal solutions. In addition, alternative sustainability criteria of farm-level agricultural practices are presented, and the optimal solution of the problem is evaluated to determine if it meets any or all of the definitions of sustainability.Farm Management,

    Economic and Environmental Impacts of Adoption of Genetically Modified Rice in California

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    Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

    EXPLAINING INTERNATIONAL DIFFERENCES IN GENETICALLY MODIFIED FOOD LABELING REGULATIONS

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    Replaced with revised version of paper 07/13/04.Food Consumption/Nutrition/Food Safety,

    Hypercube matrix computation task

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    A major objective of the Hypercube Matrix Computation effort at the Jet Propulsion Laboratory (JPL) is to investigate the applicability of a parallel computing architecture to the solution of large-scale electromagnetic scattering problems. Three scattering analysis codes are being implemented and assessed on a JPL/California Institute of Technology (Caltech) Mark 3 Hypercube. The codes, which utilize different underlying algorithms, give a means of evaluating the general applicability of this parallel architecture. The three analysis codes being implemented are a frequency domain method of moments code, a time domain finite difference code, and a frequency domain finite elements code. These analysis capabilities are being integrated into an electromagnetics interactive analysis workstation which can serve as a design tool for the construction of antennas and other radiating or scattering structures. The first two years of work on the Hypercube Matrix Computation effort is summarized. It includes both new developments and results as well as work previously reported in the Hypercube Matrix Computation Task: Final Report for 1986 to 1987 (JPL Publication 87-18)

    Flight Testing ALHAT Precision Landing Technologies Integrated Onboard the Morpheus Rocket Vehicle

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    A suite of prototype sensors, software, and avionics developed within the NASA Autonomous precision Landing and Hazard Avoidance Technology (ALHAT) project were terrestrially demonstrated onboard the NASA Morpheus rocket-propelled Vertical Testbed (VTB) in 2014. The sensors included a LIDAR-based Hazard Detection System (HDS), a Navigation Doppler LIDAR (NDL) velocimeter, and a long-range Laser Altimeter (LAlt) that enable autonomous and safe precision landing of robotic or human vehicles on solid solar system bodies under varying terrain lighting conditions. The flight test campaign with the Morpheus vehicle involved a detailed integration and functional verification process, followed by tether testing and six successful free flights, including one night flight. The ALHAT sensor measurements were integrated into a common navigation solution through a specialized ALHAT Navigation filter that was employed in closed-loop flight testing within the Morpheus Guidance, Navigation and Control (GN&C) subsystem. Flight testing on Morpheus utilized ALHAT for safe landing site identification and ranking, followed by precise surface-relative navigation to the selected landing site. The successful autonomous, closed-loop flight demonstrations of the prototype ALHAT system have laid the foundation for the infusion of safe, precision landing capabilities into future planetary exploration missions

    The impact of banking concentration on firm leverage in emerging markets

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    Purpose The purpose of this paper is to explore the impact of banking concentration on firm leverage in 21 major emerging countries from different geographical regions, controlling for firm determinant and macroeconomic determinant of firm leverage. Design/methodology/approach This study is based on a relatively large sample of 5,779 enterprises with total 48,280 numbers of observations over the period from 2006 to 2013 and the regression model is performed by applying two-step system general method of moment estimator methodology. Findings This study finds a positive and significant relationship between banking concentration and firm leverage. Therefore, the overall results follow the information-based theory which indicates lower firms financing obstacles as banks are more concentrated. Research limitations/implications Bank-level data of all the countries to measure banking concentration is until 2013, which restrict the empirical analysis until 2013. Also, the study conducts the analysis. Practical implications The study enables policymakers, society, and academics to have better understanding on the beneficial effects of alternative banking market structure on firms’access to credit and therefore, in determining the level of firm leverage in emerging countries. Originality/value The study represents one of the limited available empirical researches to examine the beneficial effect of alternative banking market structures of firm leverage in emerging countries

    Does political ideology matter for environmental quality outcomes?

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    A new individualized thermoregulatory bio-heat model for evaluating the effects of personal characteristics on human body thermal response

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    Personal factors such as weight, height, gender, age, and basal metabolic rate (BMR) all have significant effects on body temperature distribution and thermal sensation. A large number of well-known human body thermoregulatory models are population-based however, and cannot evaluate the impact of individual characteristics on human thermal responses. Further, the standard thermal models of the human body, including Fanger's and Gagge's, are based on the energy balance approach. However, a person's thermal sensation is affected by the thermal response of cutaneous thermoreceptors relative to the environmental thermal conditions, and it is not necessarily related to the energy balance of the human body. Thus, these simplified standard models have some limitations under various individual conditions and are not in conformity with the physiology of individual thermoregulatory mechanisms. This study proposes a new Individualized Thermoregulatory Bio-heat (ITB) model on the basis of Pennes' equation and Gagge's 2-node model to determine heat transfer in living tissue layers. In developing this model, the effects of individual parameters such as age, gender, body mass index (BMI), and BMR on determining the temperature and its derivatives at cutaneous thermoreceptor locations were considered. Afterward, the present model was validated against the published empirical data, simulated standard model results, and analytical results under various environmental conditions and a good agreement was found

    Enhancement of physical and reaction to fire properties of crude glycerol polyurethane foams filled with expanded graphite

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    The reation to fire of polyurethane foams (PUFs) has been a subject of increasing relevance, so in this study the reaction to fire performance of PUFs derived from crude glycerol (CG) has been improved using expanded graphite (EG). The influence of different loadings of EG on the physical–mechanical properties of composite foams has been assessed and the results obtained show that it has significant positive impact. Moreover, the reaction to fire of the PUF and EG/PUF composites has been investigated and the results obtained showed that the fire behavior of composite foams containing as little as 5 wt% of EG are significantly improved. Indeed a dramatic reduction of the rate of heat release, mass loss rate, effective heat of combustion and specific extinction area, has been observed even for a relative low amount of EG. Likewise, the use of Infrared Thermography as a function of time has proven that, when EG is used, the combustion stops suddenly and the temperature drops sharply compared with the behavior of the unfilled PUF sample, which suggests that EG acts like a flame extinguisher. The results obtained have proven the suitability of CG for the production of PUFs and that the addition of EG considerably improves the reaction to fire of composite foams.publishe
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