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31.
The skin is a route of exposure that needs to be considered when conducting a risk assessment. It is necessary to identify the potential for dermal penetration by a chemical as well as to determine the overall importance of the dermal route of exposure as compared with inhalation or oral routes of exposure. The physical state of the chemical, vapor or liquid, the concentration, neat or dilute, and the vehicle, lipid or aqueous, is also important. Dermal risk is related to the product of the amounts of penetration and toxicity. Toxicity involves local effects on the skin itself and the potential for systemic effects. Dermal penetration is described in large part by the permeability constant. When permeability constants are not known, partition coefficients can be used to estimate a chemical's potential to permeate the skin. With these concepts in mind, a tiered approach is proposed for dermal risk assessment. A key first step is the determination of a skin-to-air or skin-to-medium partition coefficient to estimate a potential for dermal absorption. Building a physiologically-based pharmacokinetic (PBPK) model is another step in the tiered approach and is useful prior to classical in vivo toxicity tests. A PBPK model can be used to determine a permeability constant for a chemical as well as to show the distribution of the chemical systemically. A detailed understanding of species differences in the structure and function of the skin and how they relate to differences in penetration rates is necessary in order to extrapolate animal data from PBPK models to the human. A study is in progress to examine anatomical differences for four species.  相似文献   
32.
A small-scale general equilibrium model in which the distribution of capital wealth is a key parameter is employed to examine the potential economic consequences of greater capital wealth equality. Every performance indicator examined – aggregate income, consumption equality, social welfare in the sum-of-utilities sense, and aggregate saving –is improved by greater capital wealth equality. However, the bottom-line social welfare gain, relative to the present high-inequality situation – even from the maximum achievable level of complete equality in capital wealth distribution – would be numerically rather modest.  相似文献   
33.
Are the decisions of American policymakers informed by generaltrends in the public’s ideology or by the public’spolicy-specific preferences? In this article we discuss twoexplanations for the types of public opinion information thatpoliticians collect and use. Using a unique data set of privatepolls from the White House of Richard Nixon, we find that whenopinion data on specific policies were available, the presidentrelied on them and not on general ideology data. On less importantissues, however, we find that the president often chose notto collect policy-specific data and instead relied on generalideology data. The differential collection and use of informationby policymakers reflect varying strategic calculations. Theyalso have profound implications for representative democracyand the demands placed on citizens and governors.  相似文献   
34.
Introduction   总被引:1,自引:0,他引:1  
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Many studies have provided evidence that, in birds, inexperienced breeders have a lower probability of breeding successfully. This is often explained by lack of skills and knowledge, and sometimes late laying dates in the first breeding attempt. There is growing evidence that in many species with deferred reproduction, some prebreeders attend breeding places, acquire territories and form pairs. Several behavioural tactics assumed to be associated with territory acquisition have been described in different species. These tactics may influence the probability of recruiting in the breeding segment of the population, age of first breeding, and reproductive success in the first breeding attempt. Here we addressed the influence of behaviour ('squatting') during the prebreeding period on demographic parameters (survival and recruitment probability) in a long-lived colonial seabird species: the kittiwake. We also investigated the influence of behaviour on reproductive trajectory. Squatters have a higher survival and recruitment probability, and a higher probability of breeding successfully in the first breeding attempt in all age-classes where this category is represented. The influence of behaviour is mainly expressed in the first reproduction. However, there is a relationship between breeding success in the first occasion and subsequent occasions. The influence of breeding success in the first breeding attempt on the rest of the trajectory may indirectly reflect the influence of behaviour on breeding success in the first occasion. The shape of the reproductive trajectory is influenced by behaviour and age of first breeding. There is substantial individual variation from the mean reproductive trajectory, which is accounted for by heterogeneity in performance among individuals in the first attempt, but there is no evidence of individual heterogeneity in the rate of change over time in performance in subsequent breeding occasions  相似文献   
37.
Evidence suggests that a signcant proportion, though by no means all, of bequests is equally divided among the beneficiaries. This is inconsistent with standard models of bequests, which predict that equal division should occur only by chance. This paper proposes a modified model incorporating "family fairness" as well as utilitarianism as an influence on behavior. Various implications for debt neutrality are analyzed.  相似文献   
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Abstract Both politicians and voters were asked to predict outcomesof two Oregon ballot measures in 1982. As expected, politicians'predictions always were closer to the mark than voters' were.Further, voters showed stronger signs of wishful thinking (the"Looking-Glass effect") in their predictions than did politicians.Using published preelection polls apparently improved politicians'accuracy in 1982, as well as voters' accuracy in a separate1984 survey. No other sources of data improved predictive accuracy.Findings have implications for theories of representative governmentand are consistent with a new theory of public opinion.  相似文献   
40.
Conclusions I began this article with Colin Campbell's lament about the productionist bias in sociology and the related point that most sociologists concerned with consumption have ignored private meanings and small-scale structures in favor of public meanings and large-scale structures. This article calls attention to and builds on an emerging alternative approach to what happens after production, using an understanding of the social nature of objects that springs from Marcel Mauss's distinction between gifts and commodities.Mauss's model directs attention to the conflict in industrial societies between the two realms of commodity exchange and gift exchange, which I have cast as the conflict between the world of work and the world of family, and as the contrast between commodities and possessions. Thus, the model directs attention to the fact that objects are not simply transformed in production and displayed in consumption. However important these facts may be for understanding objects and society, they do not exhaust the important ways that people experience, use, and think about the objects that surround them. In particular, Mauss's model throws into relief the problematic nature of the objects that surround us and that we use in our social relations. And in doing so it directs attention to the ways that people try to reconstruct and redefine those objects by transforming them into personal possessions. This transformation makes objects acquired as commodities suitable for gift transactions, and hence suitable for the key task of recreating social relationships and social identities, the task of creating, not merely defining, who we are and how we are related to each other.Although the Maussian model addresses many of the links between people in the worlds of work and the home, and many of the ways that objects are part of these links, I am concerned here primarily with the ways that people can appropriate commodities in the process of purchase: shopping. This concern with shopping points out the social significance of retail trade, which I take to include advertising and shopping. This is not simply a passive conduit between production and consumption. Instead, it is an important point at which objects begin to leave the realm of work, commodities, and commodity relations and enter the realm of home, possessions, and gift relations. Shopping is an ubiquitous activity in industrial society and one that is highly significant culturally: we spend vast amounts of time, energy, money, and attention on it. Doubtless part of the reason for this is utilitarian, for we need to buy to live, but it would be foolish to reduce the significance of shopping to some combination of the need of individuals to acquire in order to survive and the need of companies to generate demand in order to profit. Thus, retail trade needs to be seen as well as a set of relations and transactions between seller and buyer that define and are defined by the objects and services involved, their history, and their future. My focus on purchasing food in supermarkets has the advantage of throwing into relief the problem of appropriation, because of the impersonality of object and social relations in large, self-service supermarkets. However, the very extremity of this example can create a false impression. As I noted, in other forms of shopping the social relations between buyer and seller, like the social identity of objects, can be more personal. This personality can be real, as when buyer and seller know each other or where the object is hand-made or even unique. Alternatively, it can be more purely symbolic, as when the selling company touts itself or its employees as friendly and caring or where the manufacturer advertises the personal nature of its commodities. In some cases, indeed, the manufacturing or trading company can present itself in such a way that the company itself becomes the person with whom the purchaser transacts. In addition, because of the focus on the appropriation of commodities in purchasing, I have touched only briefly on production and the world of work more generally. As does life at home, so life at work involves the transaction of objects and labor. Relations at work, then, will shape and be shaped by the nature of what is transacted. Co-workers who transact things that are more clearly stamped with their own identity, as among service workers and craft producers, will likely have more personal relations with fellow workers than will those who transact things that are themselves relatively impersonal, as in assembly-line production. This variability in the objects and relations at work suggests that people will have diverse understandings of work, and hence of manufactured objects more generally, which will affect the need they feel to appropriate commodities. In all, though, the point of this article is simple. People use objects to create and recreate personal social identities and relationships, and in industrial capitalist societies these objects are likely to be produced and purchased as commodities and understood as manufactures in Miller's sense. Our experience with and understanding of the production and sale of objects will affect the way we use them in transactions that create and recreate social identity and relationship, and will affect our understanding of the social identities and relationships that are created and recreated. Thus, the objects that people use in social relationships mediate between realms of economy and society, between the public realms where those objects are produced and distributed, and the private realms where those objects are transacted as part of social reproduction. The fact of this mediation and its effects on people's understanding of objects and social relations deserve careful attention.
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