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Oscar Vedder Arjan L. Dekker G. Henk Visser Cor Dijkstra 《Behavioral ecology and sociobiology》2005,58(4):429-436
Allocation of parental investment is predicted to be equal at the population level between both sexes of offspring, and should lead to sex ratio biases in species that exhibit a sex-difference in parental care. Sex-differences in parental care are rarely quantified. We measured daily energy expenditure in free-living nestlings of the extremely sexually size dimorphic European sparrowhawk (Accipiter nisus), using the doubly labelled water method. These data were combined with measured growth characteristics to estimate daily and total metabolised energy intake of male and female young during the nestling stage. Females reached an asymptotic body mass 1.6 times higher than males. This resulted in a total metabolised energy an estimated 1.4 times higher for the nestling stage. Furthermore, we observed a decline in daily metabolised energy with an increase in brood size, which was significantly stronger for females than for males. These results are discussed in the context of Fishers equal allocation theory. Empirical evidence of a sex ratio bias at the end of parental care, with an overall excess of males, is lacking in this species. Consequently, our data do not support the idea of equal allocation between the sexes. The observed sex difference in daily metabolised energy in response to brood size may give scope for sex ratio bias at the level of the individual brood. 相似文献
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G. H. Schuring-Blom M. Keuzer M. E. Jakobs D. M. van den Brande H. M. Visser J. Wiegant J. M. N. Hoovers N. J. Leschot 《黑龙江环境通报》1993,13(8):671-679
In first-trimester chorionic villus sampling (CVS) for prenatal diagnosis, abnormal chromosomal findings, such as mosaicism, trisomies, or suspect abnormal karyotypes, are found more frequently than at amniocentesis. The fact that these chromosomal abnormalities do not always reflect the fetal karyotype but may be restricted to the placenta is a major problem in diagnosis and counselling. In this paper we present the results of fluorescence in situ hybridization (FISH) studies on interphase nuclei of three term placentae investigated because of false-positive findings at first-trimester CVS. The chorionic villi of the first case showed a mosaic chromosome pattern involving a trisomy 10 cell line and a normal cell line, those of the second case a total trisomy 8 cell line, while in the third case a complete monosomy X was found. Follow-up amniocentesis in each of these three cases revealed a normal karyotype. By using FISH, we were able to confirm the presence of the aberrant cell lines, which were all confined to one part of the placenta. FISH on interphase nuclei allows the investigation of large numbers of cells for the existence of numerical chromosome aberrations in a quick and reliable way. 相似文献
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J. N. Van Der Leij Dr. G. H. A. Visser M. Th. E. Bink-Boelkens J. F. Meilof C. G. M. Kallenberg 《黑龙江环境通报》1994,14(10):1003-1007
In this short communication we describe a patient with anti-SSA and anti-SSB antibodies whose first child died of congenital complete heart block (CCHB). During her second pregnancy she was treated with prednisolone, azathioprine, and plasmapheresis, and levels of anti-SSA and anti-SSB antibodies fell significantly. The pregnancy evolved uneventfully and resulted in the birth of an unaffected male infant. This is the fourth reported case of a successful outcome of pregnancy after treatment with immunosuppressive drugs in a woman with a significant risk of recurrence of CCHB. 相似文献
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A series of reactions was carried out on different surfaces using carbon and CuCl2, and KCl or HCl as a Cl-source. The PCDD/PCDF congener distribution was seen to vary to a great extent but the isomer distribution remained fairly constant. It is concluded that thermodynamic properties are largely responsible for the PCDD/PCDF isomer distribution. With pentachlorobenzene Cl2 elimination, assisted by oxygen, appears to be the major pathway for PCDD/PCDF formation. 相似文献
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Bivalves are important grazers on phytoplankton in shallow waters. However, very little is known about their ability to capture actively moving zooplankton. We investigated the escape response and success of early and late nauplii of three copepod species (Acartia tonsa, Temora longicornis and Eurytemora affinis) in the flow field of a blue mussel, Mytilus edulis, using both video observations and incubation experiments. An empirical model was created to describe the spatial distribution of the fluid deformation rate. Nauplii responded with escape jumps at mean fluid deformation rates of 0.6-1.9 sу. Escape success differed between taxa. T. longicornis was the poorest escaper, while A. tonsa and E. affinis were more efficient and similar to one another. Deformation rates differed in different parts of the flow field, which resulted in differences in escape success between the sectors. Nauplii were caught most often in the sector furthest away from the exhalent siphon, where the deformation rate was the weakest. There the nauplii were unable to detect an escape signal in time to react and flee. 相似文献
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Based on literature, we identify collaboration drivers and partner features for enhancing vertical and/or horizontal collaboration in the chemicals using industries. We further develop constructs for both types of collaboration. A survey-based analysis within the largest chemical cluster worldwide was carried out to verify and to test our literature-based constructs. Using our empirically based results, we develop and propose a framework for Advancing and Stimulating Collaboration (ASC) in the chemical industry. This framework can be used to increase collaborative arrangements within the chemical industry and thereby lead to more sustainable chemical product and process flows and management practices resulting in more sustainable chemical industrial parks. 相似文献
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Observations of copepod feeding and vertical distribution under natural turbulent conditions in the North Sea 总被引:1,自引:0,他引:1
We present results of simultaneous measurements of turbulent-dissipation rate, zooplankton vertical distribution and copepod
gut pigments in the northern North Sea. Analysis shows that some, but not all, copepods (by species, sex and stage) exhibit
significant dependence on turbulence in respect to vertical distribution and feeding rate. Oithona similis (female and copepodite stages) exhibits an avoidance of the surface layer when turbulence is strong there. For the range
of turbulence (10−7 to 10−3 m2 s−3) and ambient chlorophyll concentration (0.5–0.8 μg l−1) encountered, Calanus spp. and Metridia lucens exhibited a significant negative response in feeding-rate index with increasing turbulence. Centropages typicus and Pseudocalanus spp. also exhibited a negative response but of less significance.
Received: 12 October 2000 / Accepted: 11 December 2000 相似文献