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41.
Summary In parasitoid wasps, self-superparasitism (oviposition into a host already parasitized by the female herself) often contributes less to the reproductive success of the parasitoid than oviposition into a host previously parasitized by a conspecific (conspecific superparasitism). It could therefore often be profitable for parasitoids to avoid self-superparasitism. This requires a mechanism for either (1) the avoidance of previously searched areas and/or (2) the rejection of hosts containing eggs laid by the searching female. We investigated whether the solitary parasitoid Epidinocarsis lopezi is able to avoid self-superparasitism. We show that visits to previously searched patches were shorter than visits to unsearched patches and conclude that E. lopezi females leave a trail odour on patches they have searched. No differences were found between the time on patches previously searched by the wasp itself and on patches visited by conspecifics. However, E. lopezi superparasitizes fewer hosts previously parasitized by itself than hosts parasitized by a conspecific. Thus, they recognize an individual-specific mark in or on the host. We discuss how patch marking and host marking enable E. lopezi to avoid self-superparasitism.  相似文献   
42.
CP6的一个成果就是开发全球清洁生产信息网的承诺.基于现有网络的经验,概述了维持此全球网络的责任、努力的程度和所需的资源.叙述了为改善信息交流所做的四个现有的地区性尝试.  相似文献   
43.
We describe a probabilistic sampling design of circular permanent plots for the long-term monitoring of protected dry grasslands in Switzerland. The population under study is defined by the perimeter of a national inventory. The monitoring focus is on the species composition of the protected grassland vegetation and derived conservation values. Efficient trend estimations are required for the whole country and for some predefined target groups (six biogeographical regions and eleven vegetation types). The target groups are equally important regardless of their size. Consequently, intensified sampling of the less frequent groups is essential for sample efficiency. The prior information needed to draw a targeted sample is obtained from the sampling frame and external databases. The logistics and generalized delineation of the target population may pose further problems. Thus, investments in fieldwork and travel time should be well balanced by selecting a cluster sample. Second, any access problems in the field and non-target units in the sample should be compensated for by selecting reserve plots as they otherwise may considerably reduce the effective sample size. Finally, the design has to be flexible as the sampling frame may change over time and sampling intensity might have to be adjusted to redefined budgets or requirements. Likewise, the variables and biological items of interest may change. To fulfil all these constraints and to optimally use the available prior information, we propose a multi-stage self-weighted unequal probability sampling design. The design uses modern techniques such as: balanced sampling, spreading, stratified balancing, calibration, unequal probability sampling and power allocation. This sampling design meets the numerous requirements of this study and provides a very efficient estimator.  相似文献   
44.
Till Tolasch 《Chemoecology》2008,18(3):177-180
Summary.   Ectinus aterrimus (L.) is a fairly common European click beetle species which develops mainly in forests. In pheromone gland extracts of female E. aterrimus, examined using gas chromatography – mass spectrometry (GC-MS), one single compound was present. This was identified as 7-methyloctyl 9-methyldecanoate by comparison with a synthetic sample. Field trapping trials revealed a highly significant attraction of male E. aterrimus towards this ester. The structure of the compound differs remarkably from the pheromones of the closely related Agriotes spp., which exclusively use terpene esters.  相似文献   
45.
Civic ecology practices, such as community gardening and citizen-led urban reforestation and wetland restoration, provide opportunities for social learning. Because social learning is an important component of community resilience, we suggest that civic ecology practices can be a strategy for responding to and mitigating environmental disturbances in an era threatened by climate change. Despite the links between civic ecology, social learning and community resilience, empirical research that systematically considers these connections is limited. This study addresses this gap by introducing ‘frames’ as an approach to considering social learning outcomes and process. More specifically, we provide a model for investigating the role civic ecology education programs play in shaping youths’ capacity to understand and respond to environmental disturbance. We used participant observation and cognitive mapping to assess social learning among three youth restoration programs working in the wake of Hurricane Sandy in New York, NY, and after the 2013 floods in Boulder, CO. In all three programs, youth demonstrated social learning and cognitive change by shifting their emphasis from the impacts of disturbance towards a solutions-based framing that focused on community, action, and mitigation. However, the depth of these changes was not uniform across all programs, suggesting that variations in program length, community context, social identity, and opportunities for self-defined action may shape overall impacts of programs and youth capacity for future action.  相似文献   
46.
Radionuclide concentrations in air from uranium milling emissions were estimated for the town of Uravan, Colorado, USA and the surrounding area for a 49-yr period of mill operations beginning in 1936 and ending in 1984. Milling processes with the potential to emit radionuclides to the air included crushing and grinding of ores; conveyance of ore; ore roasting, drying, and packaging of the product (U(3)O(8)); and fugitive dust releases from ore piles, tailings' piles, and roads. The town of Uravan is located in a narrow canyon formed by the San Miguel River in western Colorado. Atmospheric transport modeling required a complex terrain model. Because historical meteorological data necessary for a complex terrain model were lacking, meteorological instruments were installed, and relevant data were collected for 1 yr. Monthly average dispersion and deposition factors were calculated using the complex terrain model, CALPUFF. Radionuclide concentrations in air and deposition on ground were calculated by multiplying the estimated source-specific release rate by the dispersion or deposition factor. Time-dependent resuspension was also included in the model. Predicted concentrations in air and soil were compared to measurements from continuous air samplers from 1979 to 1986 and to soil profile sampling performed in 2006. The geometric mean predicted-to-observed ratio for annual average air concentrations was 1.25 with a geometric standard deviation of 1.8. Predicted-to-observed ratios for uranium concentrations in undisturbed soil ranged from 0.67 to 1.22. Average air concentrations from 1936 to 1984 in housing blocks ranged from about 2.5 to 6 mBq m(-3) for (238)U and 1.5 to 3.5 mBq m(-3) for (230)Th, (226)Ra, and (210)Pb.  相似文献   
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The experiences with 1500 midtrimester prenatal diagnoses are reported. Abnormal findings of amniotic fluid investigations led to 43 therapeutic abortions. In ± 30 percent of the chromosome anomalies diagnosed, the significance of the effect on fetal development was inconclusive. The outcomes of all pregnancies except one are known. Fetal loss and perinatal mortality involved 69 cases, 23 (33 percent) of which occurred within three weeks after amniocentesis. In these 23 cases there appeared to be a relationship between the degree of experience of the gynaecologist and fetal loss: 3·7 percent when this experience was limited to a maximum of 10 punctures diminishing to 0·3 percent with an experience of more than 50 punctures. It is concluded that the risk of an abortion due to amniocentesis decreases as the gynaecologist becomes more experienced with the puncture technique.  相似文献   
50.
Fetal chromosome analysis in a 39-year-old mother revealed a chromosome 11 aberration interj ireted as a duplication of the centromere. This was also found in the mother's karyotype, raising the possibility that the abnormality was a new variant of no clinical consequence.  相似文献   
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