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Despite recent rapid increases in the occurrence of nonindigenous marine organisms in the marine environment, few studies have critically examined the invasion process for a marine species. Here we use manipulative experiments to examine processes of invasion for the Asian kelp Undaria pinnatifida (Harvey) Suringar at two sites on the east coast of Tasmania. Disturbance to reduce cover of the native algal canopy was found to be critical in the establishment of U. pinnatifida, while the presence of a stable native algal canopy inhibited invasion. In the first sporophyte growth season following disturbance of the canopy, U. pinnatifida recruited in high densities (up to 19 plants m−2) while remaining rare or absent in un-manipulated plots. The timing of disturbance was also important. U. pinnatifida recruited in higher densities in plots where the native canopy was removed immediately prior to the sporophyte growth season (winter 2000), compared with plots where the canopy was removed 6 months earlier during the period of spore release (spring 1999). Removal of the native canopy also resulted in a significant increase in cover of sediment on the substratum. In the second year following canopy removal, U. pinnatifida abundance declined significantly, associated with a substantial recovery of native canopy-forming species. A feature of the recovery of the native algal canopy was a significant shift in species composition. Species dominant prior to canopy removal showed little if any signs of recovery. The recovery was instead dominated by canopy-forming species that were either rare or absent in the study areas prior to manipulation of the canopy.  相似文献   
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Using cub growth as an index, I examine the influence of maternalnutrition, litter size, and cub sex on maternal care in cheetahs(Acinonyx jubatus) and compare cub and litter growth rates withthose of other large feilds. Seventy-nine free-living cheetahcubs in 21 litters from 15 mothers were weighed at least oncebetween 6 and 48 days of age. Eleven litters were weighed atthe beginning and end of a 5-day observation of their mothers.The mean cub growth rate varied significantly between litters,due primarily to differences in maternal food intake. Growthdeclined sharply when maternal food intake was less than 1.5kg/ day, but did not increase with greater levels of food intake.Lower limits of growth rates may therefore have been set bythe mother's food intake, whereas upper limits may be set bythe intrinsic physiological ability of cubs to grow. Althoughmale cubs were heavier than female cubs in the same litter whenfirst weighed, major differences in growth rate between thesexes were not apparent at this stage. Both cheetah cubs andlitters grow fast relative to other large felids, and I arguethat this may be an adaptation to the high rate of cheetah juvenilemortality from predation.  相似文献   
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Ian McDaniel 《Bioethics》2015,29(4):291-299
This article considers the objection to abortion that a woman who voluntarily engages in sexual activity is responsible for her fetus and so cannot have an abortion. The conclusion argued for is that the conceptions of responsibility that can ground the objection that are considered do not necessitate a requirement on the part of a pregnant woman to carry her pregnancy to term. Thus, the iterations of the responsibility objection presented cannot be used to curtail reproductive choice.  相似文献   
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Environmental management, being an important component in strategies for achieving sustainable development of processes and products, has emerged as a proactive approach in majority of the manufacturing organizations. From the strategic perspective environmentally conscious manufacturing (ECM) programs lead to better environmental management practice. The objective of the current paper is to present an integrated and holistic framework to evaluate ECM programs. This framework combines three multi-criteria decision analysis (MCDA) methods to consider eight major environmentally conscious manufacturing indicators (ECMI) in order to identify the efficiency of each ECM program. First the interdependence relationship among the ECMIs is established using decision-making trail and evaluation laboratory (DEMATEL). Then a range of weightage (i.e. upper and lower bounds) is created for each ECMI using analytic network process (ANP) to include managerial preferences. Finally, this range of weightage for each indicator is applied to perform restricted multiplier data envelopment analysis (RMDEA). Results show that the technical efficiency of the inefficient ECM programs for integrated RMDEA, on average, is calculated as 53.2% whereas traditional input oriented DEA provides the same score as 72.3%. This clearly indicates that integrated RMDEA is better than the input oriented DEA because same level of output could be produced with lesser resources if the ECM programs perform on the frontier. Hence, the advantage of this methodology is that the managerial preferences are successfully implemented through this newly developed hybrid methodology that will help to reduce less resource consumption and lead to better environmental policy.  相似文献   
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We develop an improved approach to evaluate car sharing options under uncertain environments with the combination of Fuzzy Analytic Hierarchy Process (F-AHP) and Fuzzy Technique for Order Preference by Similarity to Ideal Solution (F-TOPSIS), which consists of three steps. In the first step, we propose a SCUMN (Specific, Comprehensive, Understandable, Measurable, and Neutral) methodology to identify appropriate indicators and obtain a final list of 24 indicators according to their relevance to car sharing options. In the second step, we determine the weight of each indicator with F-AHP and conduct consistency check of the comparison matrix of selected indicators. In the third step, comparison of different options is performed with selected indicators and F-TOPSIS. A case study is provided to validate the proposed approach. Twenty-four indicators are identified to evaluate five different car sharing options and rank them according to their closeness coefficients in decreasing order. And thirty-one sensitivity analysis experiments are conducted to figure out the influence of indicators on decision making. The experimental results show that the proposed approach is capable of evaluating car sharing options with uncertainty and vagueness. F-AHP is able to determine the weight for each selected indicator and F-TOPSIS demonstrates its advantage in comparing potential options.  相似文献   
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In the literature on medical ethics, it is generally admitted that vulnerable persons or groups deserve special attention, care or protection. One can define vulnerable persons as those having a greater likelihood of being wronged – that is, of being denied adequate satisfaction of certain legitimate claims. The conjunction of these two points entails what we call the Special Protection Thesis. It asserts that persons with a greater likelihood of being denied adequate satisfaction of their legitimate claims deserve special attention, care or protection. Such a thesis remains vague, however, as long as we do not know what legitimate claims are. This article aims at dispelling this vagueness by exploring what claims we have in relation to health care – thus fleshing out a claim‐based conception of vulnerability. We argue that the Special Protection Thesis must be enriched as follows: If individual or group X has a greater likelihood of being denied adequate satisfaction of some of their legitimate claims to (i) physical integrity, (ii) autonomy, (iii) freedom, (iv) social provision, (v) impartial quality of government, (vi) social bases of self‐respect or (vii) communal belonging, then X deserves special attention, care or protection. With this improved understanding of vulnerability, vulnerability talk in healthcare ethics can escape vagueness and serve as an adequate basis for practice.  相似文献   
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Spatial distribution of ant workers and, notably their aggregation/segregation behaviour, is a key-element of the colony social organization contributing to the efficiency of task performance and division of labour. In polymorphic species, specialized worker castes notably differ in their intrinsic aggregation behaviour. In this context, knowing the preponderant role of minors in brood care, we investigate how a stimulus such as brood can influence the spatial patterns of Pheidole pallidula worker castes. In a homogeneous area without brood, it was shown that minors display only a low level of aggregation while majors form large clusters in the central area. Here we find out that these aggregation patterns of both minors and majors can be deeply influenced by the presence of brood. For minors, it nucleates or enhances the formation of a large stable cluster. Such high sensitivity of minors to brood stimuli fits well with their role as main brood tenders in the colony. For majors, interattraction between individuals still remains the prevailing aggregation factor while brood strongly influences the localisation of their cluster. We discuss how the balance between interattraction and sensitivity to environmental stimuli determines the mobility of each worker castes and, consequently, the availability of minors and majors to participate in everyday colony tasks. Moreover, we will evoke the functional value of majors’ cluster location close to the brood, namely with respect to social regulation of the colony caste ratio. Received 30 May 2005; revised 11 January 2006; accepted 13 January 2006.  相似文献   
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