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31.
Nearly every epidemiologic study of residential magnetic fields and childhood leukemia has exhibited a positive association. Nonetheless, because these studies suffer from various methodologic limitations and there is no known plausible mechanism of action, it remains uncertain as to how much, if any, of these associations are causal. Furthermore, because the observed associations are small and involve only the highest and most infrequent levels of exposure, it is believed that the public health impact of an effect would be small. We present some formal analyses of the impact of power-frequency residential magnetic-field exposure (as measured by attributable fractions), accounting for our uncertainties about study biases as well as uncertainties about exposure distribution. These analyses support the idea that the public health impact of residential fields is likely to be limited, but both no impact and a substantial impact remain possibilities in light of the available data. 相似文献
32.
朱世江 《西南科技大学学报(哲学社会科学版)》1995,(4)
用磁感应强度为0.01T的磁场处理豌豆种子或用该磁场处理的水浸种显著促进豌豆幼苗的营养生长,增加干物质累积量,而用同样磁场处理的水浇灌胚根已经伸出的种子则显著抑制幼苗生长及干物质积累。 相似文献
33.
在非接触式手机移动支付日益盛行的背景下,结合智能卡、RFID、磁控等技术,提出一种磁控RF-SIM卡的设计和实现模式.该磁控RF-SIM卡由多芯片的硬件架构和多任务、多应用的卡操作系统软件架构组成.它为RF-SIM卡产品带来更大的竞争力,为推动手机移动支付的发展提供了有益的帮助. 相似文献
34.
Alexander Styhre 《Culture and Organization》2013,19(4):361-376
Much practice within organizations is to some extent embodied in and centered on the visual capacities of the agent, the acting subject. Distinguishing between ‘epistemologies of the eye’, i.e. theories of how knowledge is acquired through visual practices, and ‘practices of seeing’, i.e. theories and studies of how vision and visuality are actually used in everyday working life, the paper points to the need to understand vision and visuality in organizational practice. Using the case of functional magnetic resonance imaging (fMRI), it is suggested that professional vision, i.e. practices of seeing that are shared within epistemic communities, is firstly technologically mediated and, secondly, based on the ability to combine vision, speech, gesture, and other embodied and cognitive resources in order to make sense of the images produced by fMRI technology. The paper concludes that organization theory should examine practices of seeing in greater detail and as part of the project in order to understand how knowledge is constituted and used as a collectively constituted resource within organizations. 相似文献
35.
Specialized and up-to-date knowledge is required to identify and manage the risks associated with advanced biomedical research. Additional complexities need to be considered when the research involves infants or young children. In this article, we focus on recent information about the physical risks of pediatric magnetic resonance imaging research and highlight information gaps. With an eye to assisting institutional review boards and researchers, we consider strategies for the management of these risks and formulate key questions aimed at exposing hidden hazards. Institutional review boards should ask these questions, and researchers should bear them in mind as they develop research protocols. 相似文献
36.
Jennifer Marshall 《Accountability in research》2013,20(2):67-78
Unknown harms are by their nature difficult to communicate. While magnetic resonance imaging (MRI) has known risks (e.g., metal projectiles, dislodgement of medical implants), this imaging modality also has potential unknown long-term negative health effects associated with its static magnetic fields. We carried out a research ethics board (REB) file review of previously approved MRI research studies and found that unknown risks were either left undisclosed or were inadequately disclosed to research participants and REBs. This article outlines issues raised by our REB file review and suggests steps that should be taken in order to satisfactorily communicate information about potential unknown harms of MRI. 相似文献
37.
Xiucai Ding Dengdeng Yu Zhengwu Zhang Dehan Kong 《Revue canadienne de statistique》2021,49(1):150-181
We propose a multivariate functional response low‐rank regression model with possible high‐dimensional functional responses and scalar covariates. By expanding the slope functions on a set of sieve bases, we reconstruct the basis coefficients as a matrix. To estimate these coefficients, we propose an efficient procedure using nuclear norm regularization. We also derive error bounds for our estimates and evaluate our method using simulations. We further apply our method to the Human Connectome Project neuroimaging data to predict cortical surface motor task‐evoked functional magnetic resonance imaging signals using various clinical covariates to illustrate the usefulness of our results. 相似文献
38.
39.
武保剑 《电子科技大学学报(社会科学版)》2009,(5)
磁光光纤光栅是一种具有磁光效应的特殊光栅,可直接用于本征型的磁场传感或通过磁控的方式实现可调光子信息处理。该文采用分段均匀模型分析了几种组合磁光光纤Bragg光栅中左右旋圆偏振光的偏振相关损耗对磁场的敏感性,计算表明,均匀磁光光纤光栅的中心区段对磁场最为敏感。提出了一种比均匀磁光光栅更加灵敏的F-P型组合光栅传感结构,可更好地用于较弱磁场下偏振相关损耗的检测。 相似文献
40.
丁立申 《上海理工大学学报(社会科学版)》2000,(1):29-34
根据电磁流量计的基本原理,对其微流量测量技术进行了研究。文中提出了一种运用等效坎截面法的变器结构设计,并对相应的权重函数和阻力损失进行了计算。通过对几种信号处理方法的比较,选择了较佳的基线信号处理方法。在此基础上,围绕单片机展开设计,实现了仪表的智能化和有效的功能。根据流量计栓定规程对样机进行实液标定的结果表明,样机设计达到了预期效果。 相似文献