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Andy L. Sandy Jia Guo Robert J. Miskewitz Wade R. McGillis Lisa A. Rodenburg 《Chemosphere》2013,90(5):1637-1643
Air–water exchange is an important process controlling the fate of many organic chemicals in the environment. Modeling this process is hampered by the lack of direct observations. Thus, the purpose of this work was to derive direct measurements of the mass transfer coefficients for air–water exchange (vaw) of polychlorinated biphenyls (PCBs) that may be used to check the validity of values derived from tracer gas experiments. vaw values for PCBs were determined using previously published turbulent fluxes divided by the corresponding dissolved phase concentrations. The median vaw values for each homolog decreased with increasing molecular weight and ranged from 0.29 for hexachlorobiphenyls to 2.2 m d?1 for monochlorobiphenyls with a propagated uncertainty of about 70%, lower than in previous studies. Due to relatively low wind speeds and possible sorption of PCBs to colloids, these numbers may be biased low. These field measurements of vaw differ by as much as a factor of 23 from predictions based on the widely-used Whitman two-film model. Therefore a new formulation for the calculation of vaw based on field measurements is needed. This study demonstrates that micrometeorological approaches are a viable option for the measurement of vaw for hydrophobic organics such as PCBs and should be used to generate enough field data on the air–water exchange of hydrophobic organics to allow the development of new predictive models. 相似文献
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Thorsten Stahl Sandy Falk Alice Rohrbeck Sebastian Georgii Christin Herzog Alexander Wiegand Svenja Hotz Bruce Boschek Holger Zorn Hubertus Brunn 《Environmental Sciences Europe》2017,29(1):17
Background
When cooking on a barbecue grill, consumers often use aluminum grill pans. For one, the pan catches the fats and oils that would drip into the embers causing the formation of potentially noxious smoke, and the pan also protects the food from being burned by direct heat from the coals. In addition, new aluminum products for use in ovens and grills are becoming increasingly popular. Due to their light weight and excellent heat transfer camping, utensils made of aluminum are, for example, often used by fishermen and mountain climbers. Preparing food in aluminum utensils can, however, result in migration of the aluminum to the foodstuffs.Results/Conclusions
In this study presented here, it was found that the transfer limit of 5.00 mg/L for aluminum is not exceeded using simulants for oil or for tap water; however, with an aqueous solution of 0.5% citric acid, the limit is clearly exceeded at 638 mg/L. This means that the Tolerable Weekly Intake (TWI) is exceeded by 298% for a child weighing 15 kg and for an adult weighing 70 kg it is equivalent to 63.8% of the TWI, assuming a daily uptake of 10 mL marinade containing lemon juice over a period of 1 week. Preparation of a fish dish with a marinade containing lemon juice in camping dishes would result in the TWI being exceeded by 871% for a child weighing 15 kg and by 187% for an adult weighing 70 kg assuming a daily uptake of 250 g over a period of 1 week.3.
Idiosyncratic deals in contemporary organizations: A qualitative and meta‐analytical review 下载免费PDF全文
Idiosyncratic deals (i‐deals) research focuses on the emergence of customized work arrangements employees negotiate with their employers. This article provides a critical review and synthesis of i‐deals research, combining a qualitative review of i‐deals theory and research with a supplementary meta‐analysis of 23 empirical studies (k = 27 samples, N = 8110 individuals). The qualitative review examines the conceptualization and measurement of i‐deals and identifies patterns and gaps in i‐deals research, while the quantitative meta‐analysis tests the moderating effect of societal cultures on the predictors and consequences of ideals investigated to date. In each section, attention is given to strengths and weaknesses of current approaches to i‐deals theory and research. Future research directions are identified with particular emphasis on the largely unexamined role of i‐deals from a multilevel perspective. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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The ability of many insects to learn has been documented. However, a limited number of studies examining associative learning in medically important arthropods has been published. Investigations into the associative learning capabilities of Culex
quinquefasciatus Say were conducted by adapting methods commonly used in experiments involving Hymenoptera. Male and female mosquitoes were able to learn a conditioned stimulus that consisted of an odor not normally encountered in nature (synthetic strawberry or vanilla extracts) in association with an unconditioned stimulus consisting of either a sugar (males and females) or blood (females) meal. Such information could lead to a better understanding of the ability of mosquitoes to locate and select host and food resources in nature. 相似文献
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Using meta‐analysis, we compare three attitudinal outcomes (i.e., job satisfaction, affective commitment, and turnover intent), three behavioral outcomes (i.e., interpersonal deviance, organizational deviance, and work performance), and four health‐related outcomes (i.e., general health, depression, emotional exhaustion, and physical well being) of workplace aggression from three different sources: Supervisors, co‐workers, and outsiders. Results from 66 samples show that supervisor aggression has the strongest adverse effects across the attitudinal and behavioral outcomes. Co‐worker aggression had stronger effects than outsider aggression on the attitudinal and behavioral outcomes, whereas there was no significant difference between supervisor, co‐worker, and outsider aggression for the majority of the health‐related outcomes. These results have implications for how workplace aggression is conceptualized and measured, and we propose new research questions that emphasize a multi‐foci approach. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Longitudinal behavioral data generally contains a significant amount of structure. In this work, we identify the structure
inherent in daily behavior with models that can accurately analyze, predict, and cluster multimodal data from individuals
and communities within the social network of a population. We represent this behavioral structure by the principal components
of the complete behavioral dataset, a set of characteristic vectors we have termed eigenbehaviors. In our model, an individual’s
behavior over a specific day can be approximated by a weighted sum of his or her primary eigenbehaviors. When these weights
are calculated halfway through a day, they can be used to predict the day’s remaining behaviors with 79% accuracy for our
test subjects. Additionally, we demonstrate the potential for this dimensionality reduction technique to infer community affiliations
within the subjects’ social network by clustering individuals into a “behavior space” spanned by a set of their aggregate
eigenbehaviors. These behavior spaces make it possible to determine the behavioral similarity between both individuals and
groups, enabling 96% classification accuracy of community affiliations within the population-level social network. Additionally,
the distance between individuals in the behavior space can be used as an estimate for relational ties such as friendship,
suggesting strong behavioral homophily amongst the subjects. This approach capitalizes on the large amount of rich data previously
captured during the Reality Mining study from mobile phones continuously logging location, proximate phones, and communication
of 100 subjects at MIT over the course of 9 months. As wearable sensors continue to generate these types of rich, longitudinal
datasets, dimensionality reduction techniques such as eigenbehaviors will play an increasingly important role in behavioral
research.
This contribution is part of the special issue “Social Networks: new perspectives” (Guest Editors: J. Krause, D. Lusseau and
R. James).
An erratum to this article can be found at 相似文献
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Based on Turner's (1960) contest‐ and sponsored‐mobility systems, a comprehensive model of the determinants of career success was examined. Human capital and motivational variables represented the contest‐mobility system whereas leader–member exchange and supervisor career mentoring represented the sponsored‐mobility system. Results based on data from 245 supervisor–subordinate dyads indicated limited support for the contest‐mobility system and strong support for the sponsored‐mobility system. Interestingly, the two forms of sponsorship were differentially related to career outcomes. Specifically, leader–member exchange was positively related to salary progression, promotability, and career satisfaction. Career mentoring, however, was only related to promotability. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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