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In many polygynous animals, parents invest more heavily in individual sons than in daughters. However, it is unclear if these differences in investment are a consequence of sex differences in the demand of offspring related to sexual size dimorphism or a consequence of parental manipulation. Here, we report on parental food delivery frequency in relation to brood size and brood sex ratio in a wild population of polygynous great reed warblers Acrocephalus arundinaceus. We used the polymorphic microsatellite loci on the Z chromosome to sex chicks. We found that paternal feeding frequency (times/h per nest) increased not with brood size, but with the proportion of males in the brood, although the demand per nest was more closely related to brood size than to brood sex ratio. Additionally, the increase in rate of paternal feeding frequency in relation to the brood sex ratio was much higher than the increase in rate of nestling food demands. Maternal feeding frequency was independent of both brood size and brood sex ratio. These results strongly suggest that fathers preferentially invest in their sons. We propose that parents can afford sex-biased parental care in animals in which food provisioning is enough for all offspring to survive. Received: 22 January 1996/Accepted after revision: 30 June 1996  相似文献   
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Transformation of all 19 chlorophenol (CP) isomers was investigated in a laboratory anaerobic methanogenic sludge that had not been exposed to synthetic chemicals. Concentration of CP was analyzed over time to calculate disappearance rate constants using first-order reaction kinetics and all possible CP degradation pathways were estimated. The rate constants ranged between 0.46 x 10(-3) and 0.161 day(-1). CPs were transformed via dechlorination. The chlorine atom at the ortho-position was the most easily dechlorinated, whereas dechlorination rate at the para-position was lowest. The overall pathways of CP transformation were much less diverse than that we previously found for contaminated sediment. The Dolfing hypothesis of microbial selection of the most thermodynamically favorable pathways was not applicable for CP transformation in this study as well as previous study performed by our group.  相似文献   
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IntroductionBleachingwastewaterfrompulppaperplantscontainsmanykindsofchlorinatedorganiccompoundswhichareprovedtobecarcinogenic,mutagenicandrefractory(Gellman,1988;Paasivirta,1988;Garden,1990;Suntio,1988;Vuorinen,1987;Seppala,1988).Severalmethods,inc…  相似文献   
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Environment, Development and Sustainability - The current literature has espoused the role of social media platforms in promoting tourism destinations. Despite such advances, limited works are...  相似文献   
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This paper describes the analyses of polychlorinated dibenzodioxins, dibenzofurans, and related compounds in diphenyl ether herbicides, CNP, NIP, and X-52. The levels of tetra-, penta-CDDs, and tetra-CDFs were about 150, 30, and 15 ppm, respectively in CNP formulations. NIP and X-52 contained lower chlorine alalogs. Isomer distribution of PCDDs in CNP agreed with an estimate from the reaction of chlorophenols. Freshwater fish samples heavily contaminated with CNP in the application season also contained 0.2 ppb of 1,3,6,8-tetra-CDD.  相似文献   
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A combination of sedimentological analysis of beach sands, field surveys and the assessment of the empirical methods for the breakwater design is used to investigate the impacts of offshore breakwaters on beach morphology along Nagahama and Ohgata. The results indicate that the nearshore sedimentation has been substantially disrupted due to the features formed behind the breakwaters stopping littoral transport, which led to sediment accretion on the updrift side of the breakwaters, and erosion on their downdrift side. Sedimentological analysis of beach sands made it possible to recognize the dominant process at the sections considered. In fact, the occurrence of strong offshore-going currents, the removal of finer mean grain size and the predominance of high-density heavy minerals led us to deduce that the two sections undergo a natural sedimentary imbalance.  相似文献   
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Bae HS  Yamagishi T  Suwa Y 《Chemosphere》2004,55(1):93-100
An anaerobic continuous-flow fixed-bed column reactor capable of degrading 3-chlorobenzoate (3-CBA) under denitrifying conditions was established, and its rate reached 2.26 mM d(-1). The denitrifying population completely degraded 3-CBA when supplied at 0.1-0.54 mM, but its activity was partly suppressed when 3-CBA was supplied at 0.89 mM. Nitrate was concomitantly consumed throughout the operation of the reactor, the amount of which was similar to or up to 35% higher than the theoretical stoichiometric value that was calculated by assuming that 3-CBA degradation is coupled with denitrification. Batch incubation experiments proved that nitrate is strictly required for 3-CBA degradation in the absence of molecular oxygen. The population also degraded 3-CBA aerobically. Benzoate and 4-CBA were degraded under denitrifying conditions as well as 3-CBA, but 2-CBA was not. Considering that the previously reported denitrifying 3-CBA-degrading cultures do not exhibit 4-CBA degradation under denitrifying conditions, nor aerobic 3-CBA degradation [FEMS Microbiol. Lett. 144 (1996) 213, Appl. Environ. Microbiol. 66 (2000) 3446], the microbial population developed in this experiment was physiologically versatile with respect to the utilization of both electron donors and electron acceptors.  相似文献   
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