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181.
Mary C. Towner 《Behavioral ecology and sociobiology》1999,46(2):82-94
This paper presents a dynamic state variable model that examines human dispersal in a land-based economy. In humans, like
other animals, many individuals disperse during their lifetimes, with extensive variability in the timing and likelihood of
dispersal by individuals of different states. The model places human and non-human dispersal in a common framework, specifically
by utilizing a cost-benefit approach. As with other animals, individual access to resources likely plays an important role
in shaping human dispersal, and the model explores the mechanisms underlying this relationship. Over a series of time steps,
individuals must decide whether to stay in their natal area or disperse, given their states (wealth, marital, and inheritance
status) and the environmental constraints on dispersal. Costs of dispersal include time and an initial drop in wealth, while
the benefit is the potential of the dispersal area to increase wealth. The model determines whether dispersing or staying
results in the highest fitness, where fitness is a function of individual wealth and years married. The model shows that dispersal
is favorable under a wide range of environmental conditions, but that it also varies predictably according to individual states.
Men of middle wealth values disperse under a wider variety of circumstances than poorer or wealthier men. Wealthy men, who
are particularly sensitive to the time cost and mortality risk associated with dispersing, appear to adopt a more conservative
dispersal strategy than poorer men, who are more sensitive to the wealth cost and wealth growth rate associated with dispersing.
Dispersal behavior is also contingent on its effects on an individual's probability of marrying or inheriting wealth. Finally,
the model fosters an examination of how the interaction of life events, and their directions of causation, can be studied.
Received: 6 May 1998 / Received in revised form: 3 February 1999 / Accepted: 7 February 1999 相似文献
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Background
To analyze population-based trends in the prenatal diagnosis of sex chromosome aneuploidy (SCA) since the availability of non-invasive prenatal testing (NIPT).Methods
Retrospective state-wide data for all prenatal diagnoses performed <25 weeks gestation from 2005 to 2020 in Victoria, Australia. Non-invasive prenatal testing became locally available from 2012. The prenatal diagnosis rates of SCA as proportions of all prenatal diagnostic tests and all births were calculated. Statistical significance was assessed with the χ2 test for trend, with p < 0.05 considered significant.Results
46,518 amniocentesis and chorionic villus sampling were performed during the study period, detecting 617 SCAs. There was a significant increase in the rate of prenatal SCAs from 5.8 per 10,000 births in 2005 to 8.7 per 10,000 births in 2020 (p < 0.0001). This increase was predominantly due to 47,XXY cases, 91% of which were ascertained via positive NIPT for this condition in 2020. The prenatal diagnosis rate of 47,XXY significantly increased from 0.8 per 10,000 births in 2005 to 4.3 per 10,000 births in 2020 (p < 0.0001).Conclusion
Screening for SCAs using NIPT has directly led to an increase in their prenatal diagnosis on a population-wide basis, especially 47,XXY. This has implications for clinician education, genetic counselling, and pediatric services. 相似文献188.
Bonny Patrice Desdouits Marion Schaeffer Julien Garry Pascal Essia Ngang Jean Justin Le Guyader Françoise S. 《Food and environmental virology》2020,12(3):274-277
Food and Environmental Virology - Shellfish constitute an important protein source but may be contaminated by viruses from various origins. A study performed on clams collected in Cameroon showed a... 相似文献
189.
Mariliz Gutterres Patrice M. Aquim Joana B. Passos Jorge O. Trierweiler 《Journal of Cleaner Production》2010,18(15):1545-1552
In tanneries, the phases of conditioning and preparing the hide for tanning, as well as the transportation and fixation of tanning substances, are all carried out in aqueous media. Most of the steps of these processes are carried out with fresh water, which is used as a vehicle for the diffusion of chemical products and the extraction of undesirable materials from the hide. The objective of this study is to provide the minimization of water consumption at tanneries by applying the reuse of water at some stages of the process. Alternatives for water reuse were evaluated through analysis of the process wastewater to determine the concentration of some contaminant parameters. In tests with half-hides, the possibility of reusing the liquors from the 2nd bating washing in the 1st bating washing, and of reusing the liquors from the pre-deliming washing in the pre-deliming operation, was verified. In industrial scale the water reuse from a mixture of bating washings in the deliming and deliming bating was tested successfully. The quality of wet-blue leather analyzed in the systems with and without water reuse did not show any considerable differences and satisfies the tannery specifications. Finally, a mathematical program for mass integration was applied to solve the problem of water reuse in the beamhouse steps. 相似文献
190.