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61.
The spatio‐temporal distribution of Psylliodes chrysocephala (L.) (Coleoptera: Chrysomelidae), a pest of oilseed rape (Brassica napus) (L.) (Cruciferae) and its potential predators, carabid beetles, within a crop of winter oilseed rape is described. The distribution of Collembola, a potential alternative food source for the predators, is also investigated. Insects were collected from spatially referenced sampling points across the crop and the counts mapped, analysed, and the degree of spatial association between the distributions determined using Spatial Analysis by Distance IndicEs (SADIE). Immigration into the crop by adult P. chrysocephala occurred from two edges and resulted in a non‐uniform distribution of the pest within the crop. Infestation of rape plants by P. chrysocephala larvae was greatest within the central area of the crop. Significant spatial association between adult female P. chrysocephala and the larval infestation of plants occurred throughout October. Three carabid species were active and abundant during peak pest immigration into the crop, viz., Trechus quadristriatus (Schrank) (Coleoptera: Carabidae), Pterostichus madidus (Fabricius) (Coleoptera: Carabidae), and Nebria brevicollis (Fabricius) (Coleoptera: Carabidae). Two of these species, T. quadristriatus and P. madidus, showed significant spatial association with the larvae of P. chrysocephala during October. All three carabid species showed a significant spatial association with Collembola during mid‐September, indicating that the latter may be an important food source for carabids during this period. In laboratory feeding experiments, only T. quadristriatus consumed the eggs of P. chrysocephala suggesting that, in the adult stage, this species may be the most important of the naturally occurring carabids as a predator of P. chrysocephala in the field. Adult T. quadristriatus may be a valuable component of an Integrated Pest Management strategy for winter oilseed rape, and the conservation of this species could be beneficial.  相似文献   
62.
63.
1. This study highlights the use of waterbird communities as potential measures of river and floodplain health at a landscape scale. 2. The abundance and diversity of a waterbird community (54 species) was measured over 15 trips with four aerial and three ground counts per trip on a 300-ha lake in arid Australia. 3. Aerial survey estimates of individual species were significantly less precise (SE/mean) than ground counts across two (11–100 and > 1000) out of four abundance classes of waterbirds: 0–10, 11–100, 101–1000 and > 1000. Standard error/mean as a percentage decreased with increasing abundance from about 60% for the lowest abundance class to 18% for the largest abundance class. 4. Aerial survey estimates were negatively biased for species in numbers of less than 10 and greater than 5000 but unbiased compared to ground counts for other abundance classes. Aerial surveys underestimated numbers of waterbirds by 50% when there were 40 000 waterbirds. Three ground counts found about seven more waterbird species than four aerial surveys. One ground count took about 150 times longer than two aerial surveys and cost 14 times more. 5. Regression models were derived, comparing aerial survey estimates to ground counts for 31 of 36 species for which there were sufficient data. Aerial survey estimates were unbiased for most of these species (67%), negatively biased for six species and positively biased for one species. Estimates were negatively biased in species that occurred in small numbers or that dived in response to the aircraft. 6. River system health encompasses the state of floodplain wetlands. Waterbirds on an entire wetland or floodplain may be estimated by aerial survey of waterbirds; this is a coarse but effective measure of waterbird abundance. Aerial survey is considerably less costly than ground survey and potentially provides a method for measuring river and floodplain health over long periods of time at the same scale as river management.  相似文献   
64.
Bhoj (1997c) proposed a new ranked set sampling (NRSS) procedure for a specific two‐parameter family of distributions when the sample size is even. This NRSS procedure can be applied to one‐parameter family of distributions when the sample size is even. However, this procedure cannot be used if the sample size is odd. Therefore, in this paper, we propose a modified version of the NRSS procedure which can be used for one‐parameter distributions when the sample size is odd. Simple estimator for the parameter based on proposed NRSS is derived. The relative precisions of this estimator are higher than those of other estimators which are based on other ranked set sampling procedures and the best linear unbiased estimator using all order statistics.  相似文献   
65.
于雪新  陈艾莉  李玥莹  刘丹  王前飞 《遗传》2018,40(11):988-997
白血病是常见的血液系统恶性肿瘤,治疗主要以化疗为主,但总体治疗效果欠佳且发病的分子机制不明。因此,白血病的发病机制以及临床研究急需新的突破口。近年来,研究人员不仅发现了急性髓系白血病耐药的新靶点,揭示不同表观修饰的相互作用加速MLL白血病进展,也阐释了NK细胞白血病发病机制,发现关键表观因子在髓系肿瘤发生中的重要功能。尤其是新抑癌基因SETD2的发现,为急性髓系白血病的治疗提供了新的靶点。此外,在国际上研究人员首次将低剂量化疗方案用于治疗初诊儿童急性髓系白血病,在不影响疗效的基础上显著降低了化疗毒副作用及治疗费用。虽然基因组特征的解析加深了我们对癌症生物学分子机制的理解,但是近年来的研究表明瘤内异质性的克隆演化也是导致白血病临床治疗效果不佳的主要因素,解析不同化疗方案下白血病患者不同的克隆演化模式及其在临床预后评估中的作用是目前的研究热点之一。上述研究为急性髓系白血病诊断及治疗方法的改进提供了新的契机。  相似文献   
66.
Interest has surged recently in removing siblings from population genetic data sets before conducting downstream analyses. However, even if the pedigree is inferred correctly, this has the potential to do more harm than good. We used computer simulations and empirical samples of coho salmon to evaluate strategies for adjusting samples to account for family structure. We compared performance in full samples and sibling‐reduced samples of estimators of allele frequency (), population differentiation () and effective population size (). Results: (i) unless simulated samples included large family groups together with a component of unrelated individuals, removing siblings generally reduced precision of and ; (ii) based on the linkage disequilibrium method was largely unbiased using full random samples but became increasingly upwardly biased under aggressive purging of siblings. Under nonrandom sampling (some families over‐represented), using full samples was downwardly biased; removing just the right ‘Goldilocks’ fraction of siblings could produce an unbiased estimate, but this sweet spot varied widely among scenarios; (iii) weighting individuals based on the inferred pedigree (to produce a best linear unbiased estimator, BLUE) maximized precision of when the inferred pedigree was correct but performed poorly when the pedigree was wrong; (iv) a variant of sibling removal that leaves intact small sibling groups appears to be more robust to errors in inferences about family structure. Our results illustrate the complex challenges posed by presence of family structure, suggest that no single optimal solution exists and argue for caution in adjusting population genetic data sets for the presence of putative siblings without fully understanding the consequences.  相似文献   
67.
Recent advances in distributed information technologies are providing the means to capture and process abundant data, and to reveal associations between variables describing the crop-environment-management interaction. This review describes the determinants and moderating factors influencing how much value a crop producer and his or her advisor can derive from data, and information derived from data. We describe the social, technological, and entrepreneurial processes needed to progress the nonlinear pathway from data to an on-farm decision, and explore the meaning of actionable knowledge; that is, knowledge that can be acted upon and applied to solve a real-world problem. We argue that effective decision support is also a system that supports the learning needs of crop producers and their transactions with trusted advisors. Crop protection, the sub-set of crop management used to mitigate crop loss, is used to illustrate current approaches and technologies to support farmers' decisions. We describe how situational awareness and actionable knowledge could be improved through use of emerging platform technologies, advances in artificial intelligence, consideration of farmer decision style, knowledge capture and maintenance, and embedding technology in human-centered services. Implications for the conduct of research and development are discussed.  相似文献   
68.
近十年来,基于单分子定位的PALM成像技术快速发展,将显微镜的分辨率提高到了2-25nm。本文发现PALM成像过程中采用的激发光强度与成像的定位精度之间有密切的联系。我们分别选择了PALM成像使用的光激活荧光蛋白、光转换荧光蛋白和光开关荧光蛋白中最常用的荧光蛋白进行验证。实验发现伴随激光强度的增加,大部分荧光蛋白的光子数先升高然后趋于饱和,背景噪声几乎线性升高。进一步分析发现荧光蛋白的定位误差随着激光强度增强先降低后升高,因此选用合适的激光强度在PALM成像实验中至关重要。如何提高PALM成像的分辨率一直是科学家研究的热点,本研究内容可以指导研究人员在PALM成像中选用合适的激发光强度,从而得到高分辨率的图像。  相似文献   
69.
The choice of the best sampling strategy to capture mean values of functional traits for a species/population, while maintaining information about traits’ variability and minimizing the sampling size and effort, is an open issue in functional trait ecology. Intraspecific variability (ITV) of functional traits strongly influences sampling size and effort. However, while adequate information is available about intraspecific variability between individuals (ITVBI) and among populations (ITVPOP), relatively few studies have analyzed intraspecific variability within individuals (ITVWI). Here, we provide an analysis of ITVWI of two foliar traits, namely specific leaf area (SLA) and osmotic potential (π), in a population of Quercus ilex L. We assessed the baseline ITVWI level of variation between the two traits and provided the minimum and optimal sampling size in order to take into account ITVWI, comparing sampling optimization outputs with those previously proposed in the literature. Different factors accounted for different amount of variance of the two traits. SLA variance was mostly spread within individuals (43.4% of the total variance), while π variance was mainly spread between individuals (43.2%). Strategies that did not account for all the canopy strata produced mean values not representative of the sampled population. The minimum size to adequately capture the studied functional traits corresponded to 5 leaves taken randomly from 5 individuals, while the most accurate and feasible sampling size was 4 leaves taken randomly from 10 individuals. We demonstrate that the spatial structure of the canopy could significantly affect traits variability. Moreover, different strategies for different traits could be implemented during sampling surveys. We partially confirm sampling sizes previously proposed in the recent literature and encourage future analysis involving different traits.  相似文献   
70.
Anthropologists often criticize the discipline of bioethics because its remote, abstract theories fail to capture how front-line clinicians experience and resolve moral uncertainty. The critique overlooks, however, the ways that everyday, emergent moral discourse is influenced—over time and through several mediations—by formal ethical notions. High-order ethical pronouncements become sedimented into the conditions of work, illustrated in this article by a two-year ethnographic study of Assertive Community Treatment (ACT), a popular mode of outpatient psychiatric services. ACT clinicians' moral unease when they break the confidentiality of patients is connected to high-order debates, dating back 35 years, about ensuring patients' autonomy without abandoning them. These debates originally spurred the invention of ACT, and they get braided into today's moral discourse through several mediations: regulatory paperwork, the mandates and micropolitics of staff–patient interactions, and the idealized self-image of front-line staff. This article shows how everyday moral talk is coproduced by both the immediate contexts of clinical work and the categories of formal bioethics.  相似文献   
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