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The stability and efficiency, especially the stability, are generally concerned issues in Q compensated reverse time migration (Q-RTM). The instability occurs because of the exponentially boosted high frequency ambient noise during the forward or backward seismic wavefield propagation. The regularization and low-pass filtering methods are two effective strategies to control the instability of the wave propagation in Q-RTM. However, the regularization parameters are determined experimentally, and the wavefield cannot be recovered accurately. The low-pass filtering method cannot balance the selection of cutoff frequency for varying Q values, and may damage the effective signals, especially when the signal-to-noise ratio (SNR) of the seismic data is low, the Q-RTM will be a highly unstable process. In order to achieve the purpose of stability, the selection of cutoff frequency will be small enough, which can cause great damage to the effective high frequency signals. In this paper, we present a stable Q-RTM algorithm based on the excitation amplitude imaging condition, which can compensate both the amplitude attenuation and phase dispersion. Unlike the existing Q-RTM algorithms enlarging the amplitude, the exponentially attenuated seismic wavefield will be used during both the forward and backward wavefield propagation of Q-RTM. Therefore, the new Q-RTM algorithm is relative stable, even for the low SNR seismic data. In order to show the accuracy and stability of our stable Q-RTM algorithm clearly, an example based on Graben model will be illustrated. Then, a realistic BP gas chimney model further demonstrates that the proposed method enjoys good stability and anti-noise performance compared with the traditional Q-RTM with amplitude amplification. Compare the Q-RTM images of these two models to the reference images obtained by the acoustic RTM with acoustic seismic data, the new Q-RTM results match the reference images quite well. The proposed method is also tested using a field seismic data, the result shows the effectiveness of our proposed method.  相似文献   
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Identification of deleterious variants in hereditary breast and ovarian cancer (HBOC) susceptibility genes allows for increased clinical surveillance and early detection, and could predict the response to poly (ADP‐ribose) polymerase (PARP) inhibitor in patients with advanced ovarian carcinomas. To determine the prevalence and clinical prediction factors for HBOC syndrome, 882 selected individuals underwent multigene panel testing for HBOC risk assessment during the period from January 2015 to March 2018. Overall, 176 deleterious mutations were observed in 19.50% (n = 172) of individuals. Twenty‐six of 176 mutations could not be retrieved in related public databases and were considered to be novel. Among patients with ovarian cancer, 115 deleterious mutations were identified in 429 patients (48.6%) with significant enrichment for a family history of breast or ovarian cancer syndrome (P < .05). In the breast cancer subgroup, 31 deleterious mutations were identified in 261 patients. Besides BRCA1 (8; 25.8%) and BRCA2 (11; 35.5%), the most frequently occurring genes, an additional 12 deleterious mutations (38.7%) were found in seven other susceptibility genes. Higher mutation incidence (57.9%) was observed in subjects with histories of breast and ovarian cancer. Our results highlighted the genetic heterogeneity of HBOC and the efficiency of a multigene panel in carrying out risk assessment.  相似文献   
65.
皮肤再生医疗技术治疗糖尿病足溃疡疗效分析   总被引:14,自引:8,他引:6  
目的:分析、总结、探讨皮肤再生医疗技术在临床上治疗糖尿病足溃疡的可行性与有效性。方法:对32例糖尿病足溃疡住院病人采用皮肤再生医疗技术为主、必要时配合植皮的治疗方法进行局部创面修复。结果:32例糖尿病足溃疡应用皮肤再生医疗技术获得修复9例(占28.1%),皮肤再生医疗技术 皮片移植12例(占37.5%),皮肤再生医疗技术 皮瓣修复5例(占15.6%),进行截肢6例(占18.8%)。结论:及时就诊、及时采用皮肤再生医疗技术为主的治疗方法能有效修复溃疡创面、降低糖尿病足截肢率。  相似文献   
66.
目的 探讨营养支持在重症心脏瓣膜病外科治疗中的作用。方法2000年5月-2005年5月对182例重症心脏瓣膜病行瓣膜置换术,围术期采用营养支持疗法。其中单瓣病变74例,二尖瓣合并主动脉瓣病变108例。135例行三尖瓣成形术,37例行左房折叠术。结果 182例住院死亡5例,死亡率2.7%,术后并发低心排15例,死亡1例,随访151例,结论 科学的应用营养支持方案,可以明显地提高重症心脏瓣膜病外科手术成功率。  相似文献   
67.
介绍了构建数字化、可视化教学平台,实现妇产科教学手段多元化的做法。内容包括多媒体课件开发制作,利用医学视听教材,建设妇产科图片数据库,建设妇产科标本库(馆),利用模型、模块进行模拟操作,加强实践技能培养和通过临床见习、实习将理论应用于实践等问题。  相似文献   
68.
We report clinical, neuroradiologic features, and neuropathologic findings of a 76‐year‐old man with coexistent Pick’s disease and progressive supranuclear palsy. The patient presented with loss of recent memory, abnormal behavior and change in personality at the age of 60. The symptoms were progressive. Three years later, repetitive or compulsive behavior became prominent. About 9 years after onset, he had difficulty moving and became bed‐ridden because of a fracture of his left leg. His condition gradually deteriorated and he developed mutism and became vegetative. The patient died from pneumonia 16 years after the onset of symptoms. Serial MRI scans showed progressive cortex atrophy, especially in the bilateral frontal and temporal lobes. Macroscopic inspection showed severe atrophy of the whole brain, including cerebrum, brainstem and cerebellum. Microscopic observations showed extensive superficial spongiosis and severe neuronal loss with gliosis in the second and third cortical layers in the frontal, temporal and parietal cortex. There were Pick cells and argyrophilic Pick bodies, which were tau‐ and ubiquitin‐positive in neurons of layers II–III of the above‐mentioned cortex. Numerous argyrophilic Pick bodies were observed in the hippocampus, especially in the dentate fascia. In addition, moderate to severe loss of neurons was found with gliosis and a lot of Gallyas/tau‐positive globus neurofibrillary tangles in the caudate nucleus, globus pallidus, thalamus, substantia nigra, locus coeruleus and dentate nucleus. Numerous thorned‐astrocytes and coiled bodies but no‐tuft shaped astrocytes were noted in the basal ganglion, brainstem and cerebellar white matter. In conclusion, these histopathological features were compatible with classical Pick’s disease and coexistence with progressive supranuclear palsy without tuft‐shaped astrocytes.  相似文献   
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邹城市预防艾滋病健康教育效果评价   总被引:6,自引:4,他引:2  
目的评价预防艾滋病健康教育与行为干预效果。方法采用问卷方式对社区居民进行预防艾滋病信息的可及性及知信行的调查。结果社区居民艾滋病知晓率为97.41%,熟悉艾滋病传播途径的87.78%,62.78%的认为艾滋病病人或感染者和正常人享有一样的入学/就业权,38.70%的人愿意与感染艾滋病的同事继续共事,60.19%的人愿意与感染艾滋病的家人继续共同生活,最近3次性行为100%使用安全套者为26.48%,82.04%的人有医疗用血安全意识,64.81%的人有医疗器械安全意识。最想获取艾滋病预防措施、传播途径、病理知识、症状表现、治疗方法、检测途径及检测方法、疫情信息,新闻、电视公益广告、专题报道、反映艾滋病病人生活的电影或电视剧、科普材料、大型公益演出人们最喜欢。结论政府重视,多部门合作,组织机构健全,宣传教育广泛,干预措施到位,成效显著。  相似文献   
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