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991.
Given the substantial impact that new ventures have on the global economy, understanding what motivates entrepreneurs is of both practical and theoretical importance. Although research on the nature, causes, and consequences of entrepreneurial motivation has grown rapidly, it has evolved in distinct theoretical silos that tend to isolate motives based on the phase of business development (e.g., initiation, growth, and exit) rather than acknowledge that individuals often traverse all these phases and experience multiple types of motivation throughout their entrepreneurial journey. To advance the study of motivation in the fields of entrepreneurship and organizational behavior and provide a means through which these advancements can contribute to our understanding of how motivation drives the start-up, growth, and exiting of businesses, we organize and review the extant literature on entrepreneurial motives based on the phases of the new venture process. In doing so, this article develops a roadmap of the current state of entrepreneurial motivation research and its nomological network and provides suggestions to guide future research in extending our understanding of motivation in the entrepreneurship domain as well as in traditional organizational settings.  相似文献   
992.

Genetically modified crops (GMCs) and climate change have been two ecological issues intensely debated over the years. The search for global solutions to the effects of climate change on agriculture has led to the proposal of GMCs as a tool to reduce the environmental impact of agricultural practices and to improve their efficiency of production. At least 27 countries, all over the world, have cultivated GMCs. The purpose of the present paper is to provide insights about the possible linkages between the cultivated areas and the CO2 emissions in these countries. In addition, the study intends to establish meaningful relationships between attributes related to the particular socio-economic situations and the environmental impacts of GMCs. Some examples are the connection between acreages of GMCs and the status of each country with respect to the Cartagena Protocol on Biosafety, as well as their classification according to the mean income per capita and their CO2 emissions. In order to give the mathematical support to these links, the methodology known as Order Theory was employed. The results show that Paraguay, India, Burkina Faso, Brazil and Pakistan could be the best contributors to the mitigation of the climate change by the reduction of their CO2 emission levels through GMCs.

  相似文献   
993.
Optimum cutting age for timber resources with carbon sequestration   总被引:1,自引:0,他引:1  
Determining the optimum cutting age for timber resources has proved to be a very challenging problem for both economists and silviculturists. Based upon Samuelson's seminal work on this issue, the majority of economists have concluded that the optimum felling age occurs at a time when the net marginal benefits fall below the current rate of interest. Recently, concern about climate change has increased the importance of forestry projects, since trees act as natural biological scrubbers by removing CO2 from the atmosphere. By incorporating these carbon sequestration benefits, this paper re-determines the optimum cutting age using a multiple rotation model. The results of this reformulation show that, in afforestation projects, trees should remain in the ground longer than the period suggested by a timber-only model in order to absorb more CO2.  相似文献   
994.
External gamma radiation levels were measured in the catchment areas of the Sharavathi River and the dose rates in air were found to be in the range 26.0-61.0 nGy h−1. Soil and sediment samples of the riverine environment were analysed for natural radionuclides such as 226Ra, 232Th and 40K using a NaI(Tl) gamma spectrometer. The activity concentration of 210Pb and 210Po in soil and sediment samples was determined by radiochemical separation techniques. Evaluation of the activity concentration of radionuclides with grain size revealed an increase in the activity of 226Ra, 232Th and 40K towards fine grain size. The activity concentrations for all isotopes in all samples were not significantly correlated with pH. However, the activity of 210Po and 210Pb in sediment showed a moderate positive correlation with organic matter content and a good correlation with clay content of sediment.  相似文献   
995.
A gas monitoring system based on broadband absorption spectroscopic techniques in the ultraviolet region is described and tested. The system was employed in real-time continuous concentration measurements of sulfur dioxide (SO2) and nitric oxide (NO) from a 220-ton h?1 circulating fluidized bed (CFB) boiler in Shandong province, China. The emission coefficients (per kg of coal and per kWh of electricity) and the total emission of the two pollutant gases were evaluated. The measurement results showed that the emission concentrations of SO2 and NO from the CFB boiler fluctuated in the range of 750–1300 mg m?3 and 100–220 mg m?3, respectively. Compared with the specified emission standards of air pollutants from thermal power plants in China, the values were generally higher for SO2 and lower for NO. The relatively high emission concentrations of SO2 were found to mainly depend on the sulfur content of the fuel and the poor desulfurization efficiency. This study indicates that the broadband UV spectroscopy system is suitable for industrial emission monitoring and pollution control.  相似文献   
996.
Population growth and environmental degradation are closely linked. Increasing population has in many rural areas of Tanzania contributed to changes in land use/cover patterns, land fragmentation and livelihood insecurity. Increasing demand for food, energy and other environmental services has contributed to expansion of agriculture, including marginal areas, and deforestation often leading to environmental degradation. Increased reliance on natural resources for rural livelihoods, subsistence nature of the agricultural sector and limited economic opportunities in rural areas are among the factors leading to rural–rural and rural–urban migrations searching for better livelihood opportunities. The high urban demand for food and biomass energy from rural areas has also contributed to rural deforestation and overall environmental degradation. This paper addresses the linkages between population and environmental degradation in Tanzania. It argues that effective implementation of development and resources management policies can lead to environmental sustainability even with growing populations. It provides evidence from successful land management interventions such as HADO, HASHI and SECAP, which support the argument that with effective implementation of resource management initiatives even larger populations can be supported by the available resources. Such successful interventions ought to be emulated elsewhere with similar environmental problems.  相似文献   
997.
This two-part paper presents the development of an improved airport risk assessment methodology aimed at assessing risks related to aircraft accidents at and in the vicinity of airports and managing Airport Safety Areas (ASAs) as a risk mitigation measure. The improved methodology is more quantitative, risk-sensitive, flexible and transparent than standard risk assessment approaches. As such, it contributes to the implementation of Safety Management Systems at airports, as stipulated by the International Civil Aviation Organisation.The second part of the paper presents the analysis of accident locations, including the plotting of Complementary Cumulative Probability Distributions for the relevant accident types. These were then used in conjunction with the improved accident frequency models to produce Complementary Cumulative Frequency Distributions that could be used to assess risks related to specific runways and determine Airport Safety Area (ASA) dimensions necessary to meet a quantitative target level of safety. The approach not only takes into account risk factors previously ignored by standard risk assessments but also considers the operational and traffic characteristics of the runway concerned. The use of the improved risk assessment technique and risk management strategy using ASAs was also demonstrated in two case studies based on New York LaGuardia Airport and Boca Raton Airport in Florida.  相似文献   
998.
This two-part paper presents the development of an improved airport risk assessment methodology aimed at assessing risks related to aircraft accidents at and in the vicinity of airports and managing airport safety areas (ASAs) as a risk mitigation measure. The improved methodology is more quantitative, risk-sensitive, flexible and transparent than standard risk assessment approaches. As such, it contributes to the implementation of Safety Management Systems at airports, as stipulated by the International Civil Aviation Organisation.The first part of the paper presents the methodological advances made in the development of accident frequency models; namely the building of a single comprehensive database of all relevant accident types, the collection and use of normal operations data in quantifying the criticality of a series of risk factors, and modelling accident frequency using multivariate logistic regression. The resulting models have better goodness-of-fit, sensitivity and specificity than standard risk assessment methodologies.  相似文献   
999.
In the past two decades, there has been continuous investment and expansion of semiconductor, photoelectric panel, or solar cell plants in the high-tech industry. For example, establishing a semiconductor plant costs about US$ 3 billion. In addition, the output value of integrated circuits (IC) of Taiwan as a whole is estimated to be about US$ 5.215 billion, and globally of US$ 275.2 billion in 2008. A large amount and a variety of specialty gases or chemicals are applied during processes in high-tech facilities and these chemicals are characterized by inflammability, toxicity, and corrosiveness. Accidents may result once errors or leaks occur in any part of the supply chain, which consists of storage facilities, supply equipment, process machines, and tail gas elimination devices. Personnel casualties can result in serious situations. This study discusses the emergency response procedures and common response defects in semiconductor plants with a view to enhancing emergency response effects and capabilities, avoiding casualties, reducing property loss and shortening operation interruption.  相似文献   
1000.
As an effort to improve the prediction of hydrogen dispersion in the atmosphere, effects of buoyancy acting on the hydrogen jets formed by releasing from high pressure vessels are investigated analytically and experimentally. For the analytical study, an integral analysis for buoyant jets and flames is carried out to yield the closed formula describing the jet and flame shapes, including their trajectory and horizontal and vertical lengths corresponding to the critical concentrations. Because the density of hydrogen after releasing from high pressure storage conditions is much close to that of helium than that of hydrogen at room temperature, helium is used as the hydrogen surrogate for the buoyant jet experiments, which were performed by visualizing the jet dispersing in the atmosphere up to the jet Reynolds number Re ~ 2400. The trajectories obtained by the integral analysis and experiments agree relatively well until the transition to turbulence occurs. A further estimate for jets and flames is made by using the integral analysis as a preliminary design to the experiments involving a much greater hydrogen release. Once the comparative investigation of the larger scale experiments with the integral analysis, we anticipate that a more universal hydrogen jet and flame data can be obtained, which perhaps leads to a better safety distance of hydrogen stations.  相似文献   
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