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21.
In order to evaluate blood levels of some perfluorinated chemicals (PFCs) and compare them to current levels of classical persistent organic pollutants (POPs) whole blood samples from Sweden were analyzed with respect to 12 PFCs, 37 polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyl-dichloroethylene (DDE), hexachlorobenzene (HCB), six chlordanes and three polybrominated diphenyl ethers (PBDEs). The median concentration, on whole blood basis, of the sum of PFCs was 20-50 times higher compared to the sum of PCBs and p,p'-DDE, 300-450 times higher than HCB, sum of chlordanes and sum of PBDEs. Estimations of the total body amount of PFCs and lipophilic POPs point at similar body burdens. While levels of for example PCBs and PBDEs are normalized to the lipid content of blood, there is no such general procedure for PFCs in blood. The distributions of a number of perfluorinated compounds between whole blood and plasma were therefore studied. Plasma concentrations were higher than whole blood concentrations for four perfluoroalkylated acids with plasma/whole blood ratios between 1.1 and 1.4, whereas the ratio for perflurooctanesulfonamide (PFOSA) was considerably lower (0.2). This suggests that the comparison of levels of PFCs determined in plasma with levels determined in whole blood should be made with caution. We also conclude that Swedish residents are exposed to a large number of PFCs to the same extent as in USA, Japan, Colombia and the few other countries from which data is available today. 相似文献
22.
Anders Jacobsson Åsa Ek Roland Akselsson 《Journal of Loss Prevention in the Process Industries》2012,25(3):561-570
This paper describes a method for assessing the effectiveness in the steps of the learning cycle: the 1st loop with reporting – analysis – decision – implementation – follow-up, and the 2nd loop on an aggregated basis. For each step, the dimensions considered the most relevant for the learning process (scope, quality, timing and information distribution) and for each dimension the most relevant aspects (e.g. completeness and detail) were defined. A method for a semi-quantitative assessment of the effectiveness of the learning cycle was developed using these dimensions and aspects and scales for rating. The method will give clear indications of areas for improvement when applied. The results of the method can also be used for correlation with other safety parameters, e.g. results from safety audits and safety climate inquiries. The method is intended to be used on a sample of the broad range of incidents normally seen in process industry companies. The method was tested on a two-year incident reporting material from six companies from various types of process industries. It was found that the method and the tools worked very well in practice. The results gave interesting insights into the effectiveness of learning from the incidents. 相似文献
23.
Behavioral Ecology and Sociobiology - Predation risk is vital in determining habitat quality. But landscapes of fear are complex and dynamic, such as temperate deciduous forests characterized by... 相似文献
24.
Summary. Colonies of two species of Metapone (M. madagascarica, M. new species.) were collected in Madagascar and established in laboratory nests. It could be demonstrated that both species
are specialist predators of termites (Cryptotermes kirbyi). During hunting the ants sting the termites and thereby paralyze and preserve the prey alive. In this way prey can be stored
in the ant nest for extended periods. During foraging and colony emigrations the ants lay chemical trails with poison gland
secretions. Among the seven compounds identified in the venom only methyl pyrrole-2-carboxylate elicits trail following behavior
in both Metapone species.
Received 11 February 2002, accepted 23 February 2002. 相似文献
25.
In ant societies, workers do not usually reproduce but gain indirect fitness benefits from raising related offspring produced
by the queen. One of the preconditions of this worker self-restraint is sufficient fertility of the queen. The queen is, therefore,
expected to signal her fertility. In Camponotus floridanus, workers can recognize the presence of a highly fertile queen via her eggs, which are marked with the queen's specific hydrocarbon
profile. If information on fertility is encoded in the hydrocarbon profile of eggs, we expect workers to be able to differentiate
between eggs from highly and weakly fertile queens. We found that workers discriminate between these eggs solely on the basis
of their hydrocarbon profiles which differ both qualitatively and quantitatively. This pattern is further supported by the
similarity of the egg profiles of workers and weakly fertile queens and the similar treatment of both kinds of eggs. Profiles
of queen eggs correspond to the cuticular hydrocarbon profiles of the respective queens. Changes in the cuticular profiles
are associated with the size of the colony the queen originates from and her current egg-laying rate. However, partial correlation
analysis indicates that only colony size predicts the cuticular profile. Colony size is a buffered indicator of queen fertility
as it is a consequence of queen productivity within a certain period of time, whereas daily egg-laying rate varies due to
cyclical oviposition. We conclude that surface hydrocarbons of eggs and the cuticular profiles of queens both signal queen
fertility, suggesting a major role of fertility signals in the regulation of reproduction in social insects. 相似文献
26.
Three recently emerging genotype classes of the genus Menippe (M. mercenaria, M. adina, and their hybrids) were examined for potential physiological correlates of gene mixing over a salinity range of 5 to 35‰.
Resting metabolic rate (RMR), as measured by oxygen uptake (V˙
O2), was highest in the hybrids. Differences in V˙
O2 could not be accounted for by differences in systemic adaptations (e.g. heart rate or scaphognathite frequency); therefore
it was concluded that they were based on potential underlying differences in carbohydrate metabolism. The higher RMR in the
hybrids was attributed to a higher metabolic cost of maintenance, resulting from the breakup of coadapted gene complexes as
a result of introgressive hybridization.
Received: 22 July 1996 / Accepted: 17 October 1996 相似文献
27.
Population structure of the Spanish sardine Sardinella aurita: natural morphological variation in a genetically homogeneous population 总被引:1,自引:0,他引:1
The importance of larval dispersal in determining the distribution and abundance of benthic marine organisms is well recognized; however, the contribution of post-larval dispersal has not been measured. I compared the dispersal of swimming larvae with that of rafting colonies in a population of compound ascidians, Botrylloides sp., living attached to leaves of the eelgrass Zostera marina in Tomales Bay, California, USA in 1990–1992. Colonies rafting on broken eelgrass traveled over 200 times farther and had comparable recruitment success relative to swimming larvae. The recruitment of rafting colonies into new habitats was facilitated by the ability of thesecolonial animals to grow asexually onto surrounding substrata. Rafting colonies brooded larvae that were subsequently relased after the colony settled into a new habitat. These results suggest that colonization of new habitats can occur by post-larvae as well as larvae, and that long-range dispersal by species with short-lived larvae may occur by post-larval rafting. 相似文献
28.
Molecular genetic variation in tarpon (<Emphasis Type="Italic">Megalops atlanticus</Emphasis> Valenciennes) in the northern Atlantic Ocean 总被引:2,自引:0,他引:2
A.?L.?McMillen-JacksonEmail author T.?M.?Bert H.?Cruz-Lopez S.?Seyoum T.?Orsoy R.?E.?Crabtree 《Marine Biology》2005,146(2):253-261
The tarpon (Megalops atlanticus) is a highly valued game fish and occasional food fish in the eastern and western Atlantic Ocean. Tarpon have a high capacity for dispersal, but some regional biological differences have been reported. In this study we used two molecular genetic techniques—protein electrophoresis of nuclear DNA loci, and restriction fragment length polymorphism analysis of the mitochondrial DNA (mtDNA)—to assess this species population genetic structure in the eastern (coastal waters off Gabon and Sierra Leone, Africa) and western (coastal waters off Florida, Caribbean Sea) Atlantic Ocean north of the equator. Genetic differentiation was observed between tarpon from Africa and tarpon from the western Atlantic Ocean. A unique allele and haplotype, significant differences in allozyme allele and mtDNA haplotype frequencies between the African and western Atlantic samples, and significant FST analyses suggest that levels of gene flow between tarpon from these two regions is low. Among the western Atlantic Ocean collections, genetic diversity values and allele and haplotype frequencies were similar. AMOVA analyses also showed a degree of genetic relatedness among most of the western Atlantic Ocean collections: however, some significant population structuring was detected in the allozyme data. A regional jackknifed FST analysis indicated the distinction of the Costa Rica population from the other western Atlantic populations and, in pairwise analyses, FST values tended to be higher (i.e., genetic relatedness was lower) when the Costa Rican sample was paired with any of the other western Atlantic samples. These data suggest that Costa Rican tarpon could be partially isolated from other western Atlantic tarpon populations. Ultimately, international cooperation will be essential in the management of this species in both the eastern and western Atlantic Ocean.Communicated by P.W. Sammarco, Chauvin 相似文献
29.
Bert Knegtering Hans Pasman 《Journal of Loss Prevention in the Process Industries》2013,26(4):821-829
During the last decade, serious accidents have continued to occur in the process industry. Apparently the scenarios of various undesired events leading to those accidents are still not sufficiently controlled. The key question is how potentially hazardous situations develop, what processes form the basis for this development, and how to control them? Safety level is not static but depends on many risk factors that change in presence and intensity over location and time. Safety level is dependent not only on technical process parameters that have immediate effects on the ‘frequency’ or probability of catastrophic consequences, but also depends on equipment integrity degradation, operational and management quality, attitudes, and cultural processes which may change over a prolonged time. The time and human interaction aspects make dynamic risk assessment complex. This paper will outline a conceptual approach using in addition to the regular process parameter signals received, also weak and slowly changing signals from various safety indicators, enabling to keep track of the risk factors. In theory this could lead to obtaining an instantaneous safety level ‘measure’ making possible forecast alarming for an imminent event to occur. Such concept could be regarded as a ‘writing’ safety barometer, or barograph. However, there are quite a number of problems to be solved which in the paper will be discussed. 相似文献
30.
Ernst Mayr: the doyen of twentieth century evolutionary biology 总被引:1,自引:0,他引:1
Hölldobler B 《Die Naturwissenschaften》2004,91(6):249-254