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Despite the practical knowledge throughout the nineteenth century that citrus fruit cured scurvy, and that rickets and beriberi were diseases caused by poor diet, it was not until 1901 that animal feeding experiments led one investigator to propose the existence of ‘accessory food factors,’ a lack of which was determined to be the cause of some illnesses (Hopkins, 1949. In Joseph Needham and E. Baldwin (eds.), Hopkins and Biochemistry, 18611947: Papers Concerning Sir Frederick Gowland Hopkins, O.M., P.R.S., with a Selection of His Addresses and a Bibliography of His Publications. Cambridge: W. Heffer and Sons Ltd). The discovery of vitamins has long been considered as a delayed discovery. This delay has been attributed to the power of the germ theory in physiology at the time. While the germ theory and theories of auto-intoxication certainly played a role in delaying the discovery of vitamins, I argue further that it is important to consider the difference made to physiology by understanding the vitamins’ catalytic function. The profound difference made to physiology by the vitamins’ catalytic function suggests that a vitamin concept had previously been systematically inaccessible to researchers working within the conceptual framework of Bernardian physiology.  相似文献   

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Thailand has experienced dramatic growth of large national and international modern food retailers, such as supermarkets, hypermarkets and convenience stores in large cities and regional centres in the last two decades. Nevertheless, Thai consumers continue to purchase perishables (fruits, vegetables and animal products) from fresh markets (wet markets, talat sot) contradicting predictions from analysts that modern food retail chains will rapidly replace fresh markets as the preferred venue for purchasing all types of foods. This paper examines trust in food retail systems as an under-explored dimension lying behind the continued patronage by Thais of fresh markets to purchase perishable items. It derives from a research program commenced in 2005 that includes fieldwork visits, interviews and questionnaires. In the context of the Thai food retail transition, we propose that trust affects relationships between consumers and (1) individual fresh market-based vendors, (2) the food products sold at fresh markets and (3) the food retail system more broadly. If fresh markets can be maintained in the face of sustained pressure from modern national and international food retailers, Thais will continue to use them. Meanwhile, trust is a relatively unrecognised dimension that is supporting the continued existence of traditional food retail formats.  相似文献   

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The restoration and rehabilitation of the native fish communities is a long-term goal for the Laurentian Great Lakes. In Lake Superior, the ongoing restoration of the native lake trout populations is now regarded as one of the major success stories in fisheries management. However, populations of the deepwater morphotype (siscowet lake trout) have increased much more substantially than those of the nearshore morphotype (lean lake trout), and the ecosystem now contains an assemblage of exotic species such as sea lamprey, rainbow smelt, and Pacific salmon (chinook, coho, and steelhead). Those species play an important role in defining the constraints and opportunities for ecosystem management. We combined an equilibrium mass balance model (Ecopath) with a dynamic food web model (Ecosim) to evaluate the ecological consequences of future alternative management strategies and the interaction of two different sets of life history characteristics for fishes at the top of the food web. Relatively rapid turnover rates occur among the exotic forage fish, rainbow smelt, and its primary predators, exotic Pacific salmonids. Slower turnover rates occur among the native lake trout and burbot and their primary prey—lake herring, smelt, deepwater cisco, and sculpins. The abundance of forage fish is a key constraint for all salmonids in Lake Superior. Smelt and Mysis play a prominent role in sustaining the current trophic structure. Competition between the native lake trout and the exotic salmonids is asymmetric. Reductions in the salmon population yield only a modest benefit for the stocks of lake trout, whereas increased fishing of lake trout produces substantial potential increases in the yields of Pacific salmon to recreational fisheries. The deepwater or siscowet morphotype of lake trout has become very abundant. Although it plays a major role in the structure of the food web it offers little potential for the restoration of a valuable commercial or recreational fishery. Even if a combination of strong management actions is implemented, the populations of lean (nearshore) lake trout cannot be restored to pre-fishery and pre-lamprey levels. Thus, management strategy must accept the ecological constraints due in part to the presence of exotics and choose alternatives that sustain public interest in the resources while continuing the gradual progress toward restoration. Received 10 December 1999; accepted 13 June 2000.  相似文献   

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This study demonstrated that fresh food produce, such as berries, sprouts, and green-leafed vegetables, sold at the retail level can contain potentially viable microsporidian spores of human-virulent species, such as Enterocytozoon bieneusi, Encephalitozoon intestinalis, and Encephalitozoon cuniculi, at quantities representing a threat of food-borne infection.  相似文献   

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The aim of this study was to characterize short- and long-term risk for consumers associated with dietary intake of pesticide residues in fruits, vegetables, and other foodstuffs available on the Polish market based on 2010–2013 official surveillance results. Among 779 samples collected from 2010 to 2013 no pesticide residue was found in 39.7% samples while 58.5% contained residues at or below the EU Maximum Residue Levels (MRLs). Non-compliances (residues above the respective MRLs) were found in 14 samples (1.8%). Most of the estimated daily intakes were well below 1% of respective acceptable daily intake (ADI) values. The highest intake for children and adults was about 7% and 1.5% of ADI, respectively. For non-compliant results acute risk was characterized. Predicted short-term intakes for children and adults ranged from 0.7% to 425%, and from 0.2% to 100% of respective acute reference dose, respectively. Results of chronic risk characterization show that consumers in Poland are adequately protected; however, incidental cases where residue levels may potentially pose a threat to consumers’ health due to acute exposure cannot be excluded.  相似文献   

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Why do individuals exhibit similar reactions to manifestly different food scares? This article examines the hypothesis of analogical reasoning, a cognitive shortcut whereby individuals anchor their risk judgements in other similar previous risky events present in their memories explains together with known determinants of risks perceptions such as risk attitudes and ambiguity aversion. Considering the distribution of risk perceptions related to three food scares that people in Europe remember, namely dioxins, genetically modified food (GMF), and bovine spongiform encephalopathy (BSE). Furthermore, the article explores whether intrinsic individual attitudes toward risk (risk aversion) or a common human reaction to lack of information, namely ambiguity aversion, are associated with perceptions of risk. The findings suggest that perceptions of the three food scares appear to be statically distributed in almost the same way, consistently with the presence of analogical reasoning. Results show that although risk perceptions were affected by a degree of ambiguity aversion, the intensity of risk perceptions is mainly explained by individual-specific risk attitudes.  相似文献   

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The relationship between environmental life cycle costing (ELCC) and sustainability was explored using two detailed wastewater case studies. The case studies were selected to increase the tension between existing market values and values for sustainability; the first case study considered incremental change to an existing plant and the second considered a paradigm shift in wastewater treatment. Pollution control provided the greatest cost savings for the first case study and provided a “win‐win” result—meeting existing standards and saving money. However, benefits for pollution control beyond current standards were not captured, which emphasized the role of standards to internalize as well as limit the values considered in ELCC. In the second case study, the value of water had the potential to change the focus of wastewater design from pollution abatement to resource recovery. However, social acceptance of recovered water and market access for resources created large risk for investment. The ELCC was also sensitive to the discount rate which limited longer‐term considerations. Other sustainability values such as scarcity and ecological thresholds were not captured. The ELCC code of practice suggests including such costs if likely in the foreseeable future; defining these values may also clarify the role of ELCC to evaluate sustainability over the life cycle.  相似文献   

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Probiotics and Antimicrobial Proteins - Tilapia production has significantly increased over the past few years due to the adoption of semi-intensive and intensive aquaculture technologies. However,...  相似文献   

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This study identified and characterized enteropathogenic Escherichia coli (EPEC) in the Canadian food supply. Eighteen of 450 E. coli isolates from food animal sources were identified as atypical EPEC (aEPEC). Several of the aEPEC isolates identified in this study possessed multiple virulence genes, exhibited adherence and attaching and effacing (A/E) lesion formation, disrupted tight junctions, and were coclassified with the extraintestinal pathogenic E. coli (ExPEC) and enterotoxigenic E. coli (ETEC) pathotypes.  相似文献   

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After reviewing recent attempts to develop sustainability indicators, this article shows how the principles of productive efficiency can be used to elaborate such indicators at the firm level. The theory of productive efficiency is somewhat expanded to incorporate fundamental issues of sustainable development: environment, equity, and futurtty. Efficiency, in the expanded notion of productive efficiency, is viewed as a necessary condition for sustainability. Working with aggregate performance indicators, it is important not to lose track of the relevant basic information. Therefore, instead of elaborating one unique indicator; we propose to implement several kinds of indicators, each of which stresses one particular focus (e.g., environmental vs. social concems). The definition of sustainable development indicators is illustrated with reference to a small data set of U.S. fossil fuel-fired electric utilities. In a sustainabiltty perspective, two important aspects are stressed, namely, the use of nonmewable resources and the inclusion of employment as a variable to maximize rather than an input to minimize. The article ends with a discussion of the significance of, and limits to, the proposed indicators.  相似文献   

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分别测定了随机限食和重喂食驯化的雌性KM小鼠的体重、摄食量、基础代谢率(BMR)、行为活动、身体脂肪和性腺重量.随机限食使摄食量增加、BMR和活动行为降低,生长发育迟缓,但对身体脂肪无显著影响.重喂食后上述指标均恢复到对照组水平,表现出显著的可塑性变化.结果表明,动物通过能量摄入和支出的权衡策略适应难以预测的食物资源变化,能量代谢和活动行为的可塑性调节在能量代谢的权衡策略中发挥重要作用.  相似文献   

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Sustainable use of nontimber forest products (NTFPs) can be affected by levels of extractions as well as by other anthropogenic influences such as fire and grazing. We examined the effects of fire on the demography of Phyllanthus emblica, an important NTFP in the forests of Biligiri Rangan Hills, India. We then assessed demographic responses to the combined effects of fire and current fruit harvesting patterns. Fruits of Phyllanthus are commercially harvested by an indigenous forest dwelling people. Using matrix population models, we compared demographic indices across a chronosequence of time since last fire. Population growth rates (λ) ranged from 0.7692 to 1.1443 across the five times since last fire. λ was the lowest at times since last fire of 2 and 3 yr. Frequent fires increased time to maturity by altering growth and survival rates, thereby causing a demographic shift from growth to regressions or negative growth. Elasticity analysis revealed that stasis of adults makes the biggest contribution to λ. Simulations of periodic and stochastic fire regimes suggest that higher λ and population persistence can be achieved at fire-return intervals of ≥7 and ≥9 yr, respectively. These fire-return intervals became longer when the simulations included harvesting and fire. Extinction probabilities under the current fire regimes (every 2–3 yr) suggest that populations will decline to lower densities. Our findings provide critical information for developing guidelines for sustainable use and management of NTFPs in Biligiri Rangan Hills, and demonstrate the need to incorporate various human-generated physical regimes in assessing sustainability of NTFPs.  相似文献   

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We consider models of the interactions between human population dynamics and cultural evolution, asking whether they predict sustainable or unsustainable patterns of growth. Phenomenological models predict either unsustainable population growth or stabilization in the near future. The latter prediction, however, is based on extrapolation of current demographic trends and does not take into account causal processes of demographic and cultural dynamics. Most existing causal models assume (or derive from simplified models of the economy) a positive feedback between cultural evolution and demographic growth, and predict unlimited growth in both culture and population. We augment these models taking into account that: (1) cultural transmission is not perfect, i.e., culture can be lost; (2) culture does not always promote population growth. We show that taking these factors into account can cause radically different model behavior, such as population extinction rather than stability, and extinction rather than growth. We conclude that all models agree that a population capable of maintaining a large amount of culture, including a powerful technology, runs a high risk of being unsustainable. We suggest that future work must address more explicitly both the dynamics of resource consumption and the cultural evolution of beliefs implicated in reproductive behavior (e.g., ideas about the preferred family size) and in resource use (e.g., environmentalist stances).  相似文献   

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