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141.
142.
The present Peru's metabolic profile study poses the specific question, What are the long‐term national energy system implications of the recent government‐supported growth of the mining sector? The question is addressed by analyzing interactions between human economic activity (in hours) and electricity input flows (in joules) in the mining sector of the Peruvian economy in 2000 and 2010, with a projection for 2020. The methodology is based on the multi‐scale integrated analysis of societal and ecosystem metabolism (MuSIASEM), which is an application of Georgescu‐Roegen's bioeconomics approach. Empirical results found for the national economy show: (1) the massive increase in size of the energy system, which is explained by exploitation of the Camisea natural gas (NG) reserves, and (2) the potential for establishing a carbon lock‐in in the electricity sector, owing to increasing construction of electricity plants based on NG as their primary energy source. Empirical results specific to the mining sector indicate: (1) the extremely high electricity metabolic rate of the mining sector (61.6 megajoules per hour in 2010), which was found to be 11 times the rate of electricity used per hour of human activity in the building and manufacturing sector in Peru, and (b) the potential increases in the proportion of electricity used in the mining sector (flow share), which could jeopardize the availability of high‐quality primary energy supplies for the rest of society. In light of these implications, it is argued that the Peruvian government's strong support for growth of the mining sector may have to be reconsidered.  相似文献   
143.
The history of fruit thinning   总被引:3,自引:0,他引:3  
The history of fruit thinning is reviewed, beginning with hand removalof fruits, the effects upon subsequent flowering, and current attemptsto develop mechanical methods of fruit removal. Early experiments withcaustic compounds and growth regulators and their subsequent developmentas commercial practices are discussed, as well as the modes of action ofgrowth regulators. Brief reviews of methods of application, factorsaffecting response, modeling to improve efficiency, and the economicvalue of thinning to the grower are also included.  相似文献   
144.
For allogeneic cell therapies to reach their therapeutic potential, challenges related to achieving scalable and robust manufacturing processes will need to be addressed. A particular challenge is producing lot‐sizes capable of meeting commercial demands of up to 109 cells/dose for large patient numbers due to the current limitations of expansion technologies. This article describes the application of a decisional tool to identify the most cost‐effective expansion technologies for different scales of production as well as current gaps in the technology capabilities for allogeneic cell therapy manufacture. The tool integrates bioprocess economics with optimization to assess the economic competitiveness of planar and microcarrier‐based cell expansion technologies. Visualization methods were used to identify the production scales where planar technologies will cease to be cost‐effective and where microcarrier‐based bioreactors become the only option. The tool outputs also predict that for the industry to be sustainable for high demand scenarios, significant increases will likely be needed in the performance capabilities of microcarrier‐based systems. These data are presented using a technology S‐curve as well as windows of operation to identify the combination of cell productivities and scale of single‐use bioreactors required to meet future lot sizes. The modeling insights can be used to identify where future R&D investment should be focused to improve the performance of the most promising technologies so that they become a robust and scalable option that enables the cell therapy industry reach commercially relevant lot sizes. The tool outputs can facilitate decision‐making very early on in development and be used to predict, and better manage, the risk of process changes needed as products proceed through the development pathway. Biotechnol. Bioeng. 2014;111: 69–83. © 2013 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.  相似文献   
145.
146.
Central paradigms of ecophysiology are that there are recognizable and even explicit and predictable patterns among species, genera, and life forms in the economics of water and nitrogen use in photosynthesis and in carbon isotope discrimination (delta). However most previous examinations have implicitly assumed an infinite internal conductance (gi) and/or that internal conductance scales with the biochemical capacity for photosynthesis. Examination of published data for 54 species and a detailed examination for three well-characterized species--Eucalyptus globulus, Pseudotsuga menziesii and Phaseolus vulgaris--show these assumptions to be incorrect. The reduction in concentration of CO2 between the substomatal cavity (Ci) and the site of carbon fixation (Cc) varies greatly among species. Photosynthesis does not scale perfectly with gi and there is a general trend for plants with low gi to have a larger draw-down from Ci to Cc, further confounding efforts to scale photosynthesis and other attributes with gi. Variation in the gi-photosynthesis relationship contributes to variation in photosynthetic 'use' efficiency of N (PNUE) and water (WUE). Delta is an information-rich signal, but for many species only about two-thirds of this information relates to A/gs with the remaining one-third related to A/gi. Using data for three well-studied species we demonstrate that at common WUE, delta may vary by up to 3 per thousand. This is as large or larger than is commonly reported in many interspecific comparisons of delta, and adds to previous warnings about simplistic interpretations of WUE based on delta. A priority for future research should be elucidation of relationships between gi and gs and how these vary in response to environmental conditions (e.g. soil water, leaf-to-air vapour pressure deficit, temperature) and among species.  相似文献   
147.
Fed-batch and perfusion culture dominate mammalian cell culture production processes. In this paper, a decision-support tool was employed to evaluate the economic feasibility of both culture modes via a case study based upon the large-scale production of monoclonal antibodies. The trade-offs between the relative simplicity but higher start-up costs of fed-batch processes and the high productivity but higher chances of equipment failure of perfusion processes were analysed. Deterministic analysis showed that whilst there was an insignificant difference (3%) between the cost of goods per gram (COG/g) values, the perfusion option benefited from a 42% reduction in capital investment and a 12% higher projected net present value (NPV). When Monte Carlo simulations were used to account for uncertainties in titre and yield, as well as the risks of contamination and filter fouling, the frequency distributions for the output metrics revealed that neither process route offered the best of both NPV or product output. A product output criterion was formulated and the options that met the criterion were compared based on their reward/risk ratio. The perfusion option was no longer feasible as it failed to meet the product output criterion and the fed-batch option had a 100% higher reward/risk ratio. The tool indicated that in this particular case, the probabilities of contamination and fouling in the perfusion option need to be reduced from 10% to 3% for this option to have the higher reward/risk ratio. The case study highlighted the limitations of relying on deterministic analysis alone.  相似文献   
148.
The paper explores the conditions that determine the effect of rule enforcement policies that imply an attempt to punish all the visible violations of the rule. We start with a simple game-theoretic analysis that highlights the value of gentle COntinuous Punishment (gentle COP) policies. If the subjects of the rule are rational, gentle COP can eliminate violations even when the rule enforcer has limited resources. The second part of the paper uses simulations to examine the robustness of gentle COP policies to likely deviations from rationality. The results suggest that when the probability of detecting violations is sufficiently high, gentle COP policies can be effective even when the subjects of the rule are boundedly rational adaptive learners. The paper concludes with experimental studies that clarify the value of gentle COP policies in the lab, and in attempt to eliminate cheating in exams.  相似文献   
149.
分析不同树种叶片性状的变化有助于了解植物群落结构。该文通过对典型阔叶红松(Pinus koraiensis)林15种阔叶树种的比叶质量、叶片厚度、叶干物质含量、叶绿素含量指数、叶片碳、氮、磷含量的测定, 分析了冠层高度对叶性状及叶性状间相关关系的影响。结果表明, 水曲柳(Fraxinus mandshurica)和大青杨(Populus ussuriensis)上层的比叶质量显著大于下层, 而其他树种冠层间的比叶质量无显著变化; 叶绿素含量指数在白桦(Betula platyphylla)和春榆(Ulmus japonica)冠层间的分布分别为上层显著大于下层和上层显著大于中层; 单位质量氮含量在水曲柳的中层显著大于上层。叶片性状间存在着广泛的相关性, 比叶质量与叶片厚度、干物质含量在三层间均呈显著正相关关系, 而有些性状, 只在一或二个冠层中存在一定的相关性。山杨(Populus davidiana)和大青杨的叶片倾向于选择光合能力较低、营养浓度较低、呼吸速率较慢的一端, 而黄檗(Phellodendron amurense)和山槐(Maackia amurensis)叶片更倾向于光合能力强、营养物质浓度高的一端。不同树种对光照响应的差异可能会改变不同冠层中叶片的形态和化学性状, 从而有助于群落构建和物种共存。  相似文献   
150.
Data on army recruits’ height are frequently available and can be used to analyze the economics and welfare of the population in different periods of history. However, such data are not a random sample from the whole population at the time of interest, but instead is skewed since the short men were less likely to be recruited. In statistical terms this means that the data are left-truncated. Although truncation is well-understood in statistics a further complication is that the truncation threshold is not known, may vary from time to time, and auxiliary information on the threshold is not at our disposal.The advantage of the fully Bayesian approach presented here is that both the population height distribution and the truncation are modeled simultaneously. The truncation threshold is allowed to be random and time-specific whilst the height distribution is assumed to change smoothly in time. Thus, in addition to the population height characteristics, we obtain also insight into recruiting criteria over time.Analysis of historical data from Swedish army recruitment in eight time events between 1768 and 1804 has found a declining trend in the mean population height during the inspected time period and also dramatic systematic changes in the recruiting.  相似文献   
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