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61.
Spire is a WH2 domain-containing actin nucleator essential for establishing an actin mesh during oogenesis. In vitro, in addition to nucleating filaments, Spire can sever them and sequester actin monomers. Understanding how Spire is capable of these disparate functions and which are physiologically relevant is an important goal. To study severing, we examined the effect of Drosophila Spire on preformed filaments in bulk and single filament assays. We observed rapid depolymerization of actin filaments by Spire, which we conclude is largely due to its sequestration activity and enhanced by its weak severing activity. We also studied the solution and crystal structures of Spire-actin complexes. We find structural and functional differences between constructs containing four WH2 domains (Spir-ABCD) and two WH2 domains (Spir-CD) that may provide insight into the mechanisms of nucleation and sequestration. Intriguingly, we observed lateral interactions between actin monomers associated with Spir-ABCD, suggesting that the structures built by these four tandem WH2 domains are more complex than originally imagined. Finally, we propose that Spire-actin mixtures contain both nuclei and sequestration structures.  相似文献   
62.
We investigated whether domestic and professional induction cooktops comply with the basic restrictions defined by the International Commission on Non‐Ionizing Radiation Protection (ICNIRP). Based on magnetic field measurements, a generic numerical model of an induction cooktop was derived in order to model user exposure. The current density induced in the user was simulated for various models and distances. We also determined the exposure of the fetus and of young children. While most measured cooktops comply with the public exposure limits at the distance specified by the International Electrotechnical Commission (standard IEC 62233), the majority exceeds them at closer distances, some of them even the occupational limits. The maximum current density in the tissue of the user significantly exceeds the basic restrictions for the general public, reaching the occupational level. The exposure of the brains of young children reaches the order of magnitude of the limits for the general public. For a generic worst‐case cooktop compliant with the measurement standards, the current density exceeds the 1998 ICNIRP basic restrictions by up to 24 dB or a factor of 16. The brain tissue of young children can be overexposed by 6 dB or a factor of 2. The exposure of the tissue of the central nervous system of the fetus can exceed the limits for the general public if the mother is exposed at occupational levels. This demonstrates that the methodology for testing induction cooktops according to IEC 62233 contradicts the basic restrictions. This evaluation will be extended considering the redefined basic restrictions proposed by the ICNIRP in 2010. Bioelectromagnetics 33:695–705, 2012. © 2012 Wiley Periodicals, Inc.  相似文献   
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64.
甘肃、新疆、内蒙苹果蠹蛾成虫消长规律   总被引:2,自引:0,他引:2  
苹果蠹蛾Cydia pomonella(L.)是我国重要的果树害虫和检疫对象。2005年至2010年,本研究在甘肃、新疆及内蒙古的不同区县选取了16个果园,使用性信息素诱捕器对其中的苹果蠹蛾成虫发生规律进行长期监测。结果表明,苹果蠹蛾在西北地区每年发生2.5个世代;在正常气候条件下,3个成虫发生高峰分别出现在5月上旬、7月中下旬和8月中下旬,但不同地区及同一地区不同果园之间存在较大差异;化学防治、迷向防治等防治措施对苹果蠹蛾成虫捕获量的影响较大,因此生活史研究为主的监测并不适合在上述果园中开展。综合上述研究结果,未对苹果蠹蛾的季节动态进行准确的预测,需要对苹果蠹蛾除成虫外的其他虫态的季节性变化进行详细研究,并建议选择3个以上的果园进行监测,综合各个果园的监测结果并得出结论。  相似文献   
65.
Xylotrechus arvicola (Olivier) (Coleoptera: Cerambycidae) is an important pest in vineyards (Vitis vinifera) in the main Iberian wine‐producing regions. Larvae were reared with Semi‐Synthetic Iglesias (SSI) diet over 27 months and two generations in the laboratory. Larval mortality was highest during the first (49.49 %) and second (9.38 %) month of rearing, increasing to 50.52 % during the first month if F2 reared larvae were obtained from an F1 adult female obtained in laboratory. The diet had sufficient nutrients to enable the pest to complete its life cycle within nine months, with F1 larval viability ranging from 23.49 % to 27.97 % and F2 larval viability reduced to 2.07 %. However, the diet did not allow for the completion of additional life cycles and generations (F3, F4,…). Larval mortality increased as the months of rearing (66.13 %, 69.51 % and 89.50 %) and generations (59.10 % and 76.93 % in F1 and F2, respectively) progressed in the laboratory. The larva–adult period of females obtained in the laboratory was longer than for males. In the laboratory, the life cycle was shortened in relation to the life cycle in the field because larvae did not require a cold period to break diapause and start pupation. This indicates that X. arvicola has the potential to complete its life cycle inside grape wood in vineyards of wine‐producing regions with warmer winters.  相似文献   
66.
安徽省蜜蜂种群消长及其分布与自然环境的关系   总被引:1,自引:0,他引:1  
2002~2004年,对淮北平原、江淮丘陵、沿江平原及皖西和皖南山区四大类型生态区域的蜜蜂种群数量动态与环境因子进行了调查.结果表明,复杂的自然环境与蜜蜂种群特性密切相关.皖南山区和皖西大别山区蜜粉源植物分别为46和37种,中华蜜蜂群体数量多,分布密度分别为2.01和1.95群·km-2;江淮地区和淮北平原蜜粉源植物分别为17和12种,花期短而集中,且面积大,适宜于意大利蜜蜂采集与生产,中华蜜蜂群体数量少,分布密度分别为0.06和0.02群·km-2.胡蜂捕食影响蜜蜂种群消长与分布.皖南山区、皖西大别山区、江淮地区和淮北平原,中华蜜蜂分别占本地区蜂群的41.5%、36.8%、3.1%和1.1%,意大利蜜蜂分别占本地区蜂群的58.5%、63.2%、96.9%和98.9%.  相似文献   
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68.
By 2050, people over 65 years old will represent 66% of the world's population. Thermal comfort both indoors and outdoors is one of the most influential factors to improve their quality of life in cities. The aim of this paper is to present a systematic review of the literature that identifies differences in thermal comfort temperature between older adults and other age groups, as well as to determine the factors that influence them. The review focused on studies published between 2000 and 2018. The results show that, for physiological, psychological, and physical reasons, there were differences between 0.2 and 4 °C. However, the published studies were heterogeneous in terms of methodologies and sample size. Likewise, few determine the comfort temperature range for older people in a given climate, demonstrating the opportunity for future lines of research.  相似文献   
69.
Peter Zwick 《Hydrobiologia》1990,194(3):207-223
Upstream oviposition flights of several Plecoptera species of the genera Leuctra, Nemoura, Isoperla and Siphonoperla along the Breitenbach, Hesse, Germany are inferred from 1. oviposition occuring upstream from emergence areas; 2. size differences and size-shifts between emerging and egg-laying females; 3. concentration of oviposition in upstream sections of the emergence area. The last point relies on direct catches of egg-laying females with sticky traps, and on over-representation of old, mature females in upstream emergence traps towards the end of, or even after actual emergence periods. Criteria for age class discrimination of the respective taxa are described. The validity of the present and of other indirect evidence for directed adult flights and the significance of adult upstream displacement are discussed. Optical orientation cues are suggested. Females of Leuctra prima and Siphonoperla torrentium are shown to gain 25–50% dry weight by feeding in the terrestrial environment; general information indicates many other Plecoptera may be similar in this respect. Terrestrial adult life is shown to last for 3–8 weeks. This long time, evidence of important flight activity and feeding together suggest that the terrestrial phase is spent as an active adult, the inevitable risks of which may form an important control of population dynamics.  相似文献   
70.
The decline in physical and mental ability often associated with increasing age in adults has both social and economic implications that affect most nations. Hence, the maintenance of functional capacity and independence of the older person are beneficial both for the individual and society alike. One way to enhance functioning in old age is physical exercise. However, few methods exist that enable older people to monitor and regulate exercise intensity without using expensive apparatus. Utilizing the individual's subjective feeling of perceived exertion through the use of a simple rating scale is an approach that differs markedly from those previously employed. The present study used the ratings of perceived exertion (RPE) scale to induce different exercise intensities in groups of older women. Walking was chosen as the type of exercise since most older women are unfamiliar with, or afraid to engage in, other types of physical exercise such as bicycling or running. Results indicated that physical exercise capacity increased after 3 months of regular low-intensity walking in the exercise groups but not in nonexercising controls. Furthermore, these changes were accompanied by improved digit span performance. In conclusion, this study has shown that the RPE scale may be used for exercise regulation and that older women would seem to be able to use the scale to monitor and regulate their exercise intensity in an outdoor environment in much the same way as younger individuals.  相似文献   
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