146 research outputs found

    Highly-efficient SPT arithmetic of fast freecube calculation

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    分析了目前国内外数据立方体计算的研究现状,首先在free-set的概念上,挖掘free-set的性质,建立了FreeCube的概念结构。然后基于BUC算法,充分考虑到free-set的性质,在对维划分的选择和free-set判断上去掉了不必要的划分和判断,从而提出了一种计算FreeCube的高效算法SPT,最后从多个角度进行了实验,并与相关工作做了对比,证明该算法具有一定的优越性。The current domestic and international research situation of data cube calculation are analyzed.Its merits and demerits are pointed out.The free-set property is excavated and the concept construction of freecube on the free-set conception is established.With regard to freecube calculation,fully considering the free-set characteristics while combining the characteristics of BUC's cal-culation,an efficient calculation way SPT is put forward.After the related work is compared,the result show the superiority of the algorithm.浙江理工大学科学基金项目(111251A4Y04002

    抗N-甲基-D-天冬氨酸受体脑炎与髓鞘少突胶质细胞糖蛋白抗体相关疾病并存的临床特征

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    【目的】探讨抗N-甲基-D-天冬氨酸受体(NMDAR)脑炎与髓鞘少突胶质细胞糖蛋白(MOG)抗体相关疾病并存患者的临床特征。【方法】回顾性分析2015 年2 月至2019 年8 月广东省中山大学附属第三医院神经内科和广州市妇女儿童医疗中心神经内科共同收治的36 例抗NMDAR 脑炎患者,其中17 例为与MOG 抗体相关疾病共存的并存组,19  例为单纯抗NMDAR  脑炎的对照组。分析总结两组患者的首发症状、影像学特征、实验室检查、治疗及预后情况。【结果】与对照组比较,并存组患者在发病性别方面男性多于女性,少合并卵巢畸胎瘤, 部分患者首发症状表现为抗 NMDAR 脑炎不常见的脱髓鞘症状,脑脊液抗 NMDAR 抗体滴度波动在(1∶1 ~ 1∶100), 血清MOG 抗体滴度波动在(1∶25 ~ 1∶1 280),病灶影像学不仅表现为累及皮质及皮质下,还表现为皮质下白质病灶或累及脊髓。从治疗及预后分析,两组患者经免疫治疗后症状均有改善,经3 ~ 50 个月随访,并存组3 例有复发, 对照组1 例有复发,均再次对免疫治疗反应良好。【结论】临床上抗NMDAR 脑炎与MOG 抗体相关疾病并存的患者在发病性别上以男性居多,成人多于儿童,合并肿瘤的情况少见,对免疫治疗反应良好,推测此类患者在免疫致病机制上具有相对的特异性

    产前滴滴涕或多氯联苯暴露与出生缺陷风险相关性的Meta分析

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    目的系统评价孕妇产前暴露于滴滴涕(DDT)或多氯联苯(PCBs)与新生儿出生缺陷风险之间的关系。方法计算机检索PubMed、EMbase、WanFang Data、VIP和CNKI数据库,搜集有关产前DDT或PCBs暴露与出生缺陷关系的病例-对照研究,检索时限均从建库至2017年2月。由2名研究者独立筛选文献、提取资料并评价纳入研究的偏倚风险后,采用Stata 13.0软件进行Meta分析。结果共纳入14个研究,包括2 238例出生缺陷新生儿和2 355例对照新生儿。Meta分析结果显示:产前暴露于高水平的DDT会导致新生儿隐睾发生率增加[OR=1.12,95%CI(1.09,1.15),P<0.001]。而DDT暴露与尿道下裂和神经管畸形发生没有相关性。产前暴露于高水平的PCBs与隐睾、尿道下裂、神经管畸形发生也没有相关性。结论孕妇产前暴露于高水平的DDT可能是隐睾发生的危险因素。受纳入研究数量和质量的限制,上述结论尚待更多高质量研究予以验证。厦门市科技计划项目(编号:3502Z20163006);;厦门市集美区科技计划项目(编号:20142C01

    旋转恒定磁场治疗激素性股骨头坏死的效果与病理机制

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    【目的】探讨旋转恒定磁场(RPMF)治疗激素性股骨头坏死的疗效和病理机理。【方法】制备新西兰兔股骨头坏死动物模型,予旋转恒定磁场(铋铁硼永磁体以8Hz频率旋转、形成其上方20cm直径60cm的半球形磁场、表面强度在0.32~0.60T之间)处理4周和8周(A1、A2组),使用组织切片和X线片以及显微CT观察股骨头内部结构变化,同时监测其血液黏稠度、胆固醇、甘油三酯以及髋关节腔压力等的变化,和相应阳性假处理4周、8周组(B1组\B2组)、空白对照(C组)进行统计学分析和比较。【结果】经旋转恒定磁场(RPMF)处理后,动物模型的股骨头骨小梁形态结构显著改善,尤以显微CT表现明显,髋关节腔压力、血液流变学及血脂检测值改善具有显著统计学意义(PEta2A*B>Eta2B)。【结论】磁场可以针对股骨头坏死主要环节高脂血症、血液黏稠度增加、关节腔压力增高等发挥调节作用,有效治疗激素性股骨头坏死,尤其是早期病变;显微CT在诊断激素性股骨头坏死方面具有灵敏性和直观的优越性

    Measurement of the Static Optoelectronic Characteristics of InGaAs/InP Avalanche Photodiode

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    建立了雪崩二极管的静态光电特性的自动测试系统。利用该系统对光敏面的直径为500μm的台面型InGaAs/InP雪崩光电二极管(APDs)进行测试。测试结果表明,该APD器件在90%击穿电压下的暗电流为151nA,在直径500μm的光敏面上其光响应均匀性良好。提出一种测量雪崩二极管倍增因子的方法,只需利用普通的测量电流-电压的测试仪器,就可以获得开始倍增时的光电流,从而得到APD的倍增因子。通过该方法得到的InGaAs/InPAPD器件最大倍增因子的典型值在10~100量级。A measurement system is set up which could measure static optoelectronic characteristics of avalanche photodiodes (APDs). By using this system, the mesa-structure InP/InGaAs APDs is measured. The results show that the APDs have a relatively low dark current (~150 nA at 90% of breakdown) and a uniform photoresponse profile of about 500 μm diameter. A method of getting APDs's multiplication gain is also proposed. Through getting the photocurrent at the point where multiplication is beginning, the multiplication gain can be obtained by the simple current-voltage equipment. For InP/InGaAs APDs, the typical maximum multiplication gain measured by this method is about 10~100

    高显色指数LED光谱配比与色度参数的关系

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    为了提高LED光源的显色性一般需要改变不同的荧光粉成分,理论上利用不同峰值的荧光粉配比可以实现类似的色温和显色指数。我们采用典型的蓝光LED、3种不同峰值波长的绿色/黄绿色荧光材料与典型红色荧光材料进行5种基本光谱的组合,对每种组合的色度学参数包括色坐标、相关色温、显色指数等进行了仿真计算,并对相近色温下的技术方案和显色性的关系进行了统计和分析。结果表明,在这一技术方案下色温和显色指数在可以较好地确定白光LED光谱的整体形态,同时更高的显色指数可以更好地约束所能采用的配比。国家重点研发计划(批准号:2017YFB0403705

    Plenty is Plague: Fine-Grained Learning for Visual Question Answering

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    纪荣嵘教授团队的论文提出了一种基于强化学习的细粒度学习策略FG-A1C,旨在通过分析视觉问答任务中的样本多样性及标签的冗余性问题来针对性地挑选训练样本以提高模型的训练效率及减少标记支出。 该论文由厦门大学媒体分析与计算实验室的周奕毅博士后助理研究员、纪荣嵘教授(通信作者)、孙晓帅副教授、苏劲松副教授,以及西安交通大学孟德宇教授、清华大学高跃副教授和澳大利亚阿德莱德大学沈春华教授等合作完成。Visual Question Answering (VQA) has attracted extensive research focus recently. Along with the ever-increasing data scale and model complexity, the enormous training cost has become an emerging challenge for VQA. In this paper, we show such a massive training cost is indeed plague. In contrast, a fine-grained design of the learning paradigm can be extremely beneficial in terms of both training efficiency and model accuracy. In particular, we argue that there exist two essential and unexplored issues in the existing VQA training paradigm that randomly samples data in each epoch, namely, the "difficulty diversity" and the "label redundancy". Concretely, "difficulty diversity" refers to the varying difficulty levels of different question types, while "label redundancy" refers to the redundant and noisy labels contained in individual question type. To tackle these two issues, in this paper we propose a fine-grained VQA learning paradigm with an actor-critic based learning agent, termed FG-A1C. Instead of using all training data from scratch, FG-A1C includes a learning agent that adaptively and intelligently schedules the most difficult question types in each training epoch. Subsequently, two curriculum learning based schemes are further designed to identify the most useful data to be learned within each inidividual question type. We conduct extensive experiments on the VQA2.0 and VQA-CP v2 datasets, which demonstrate the significant benefits of our approach. For instance, on VQA-CP v2, with less than 75% of the training data, our learning paradigms can help the model achieves better performance than using the whole dataset. Meanwhile, we also shows the effectivenesss of our method in guiding data labeling. Finally, the proposed paradigm can be seamlessly integrated with any cutting-edge VQA models, without modifying their structures.This work is supported by the National Key R&D Program (No.2017YFC0113000, and No.2016YFB1001503), Nature Sci- ence Foundation of China (No.U1705262, No.61772443, and No.61572410), Post Doctoral Innovative Talent Support Pro-gram under Grant BX201600094, China Post-Doctoral Sci- ence Foundation under Grant 2017M612134, Scientific Re-search Project of National Language Committee of China (Grant No. YB135-49), and Nature Science Foundation of Fu-jian Province, China (No. 2017J01125 and No. 2018J01106). 本项研究得到了厦门大学“人工智能分析引擎”双一流重大专项的支持、国家重点研发专项和国家自然科学基金海峡基金等项目的支持

    环孢素治疗中重度干眼症的对照研究

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    【目的】观察0.2%(2g/L)环孢素滴眼液对中重度干眼症的效果。【方法】将中重度干眼症134例随机分为对照组(65例)和实验组(69例)。对照组应用10g/L羧甲基纤维素钠,4次/d,实验组应用10g/L羧甲基纤维素钠和2g/L环孢素滴眼液,4次/d。两组均连续用药1个月。用药前后均进行荧光素染色检查、泪液分泌检查(STT)、泪膜破裂时间检测(BUT)、结膜印迹细胞检查。【结果】两组比较在治疗前差异无统计学意义(P〉0.05),治疗后实验组SIT、BUT比对照组的结果有统计学意义(P〈0.01),实验组治疗前后结果比较有统计学意义(P〈0.01)。对照组的治疗前后比较差异无统计学意义(P〉0.05)。【结论】2g/L环孢素滴眼液治疗中重度干眼确有良好的效果

    Effect of Flue-gas Cleaning Devices on Mercury Emission From Coal-fired Boiler

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    为研究燃煤锅炉烟气净化设施对汞排放特性的影响,采用Ontario-Hydro方法,对设有催化脱硝、静电除尘、海水脱硫的300MW燃煤锅炉排放烟气中汞的含量与形态进行分析,同时测定锅炉的煤、底渣、飞灰等固体样品以及脱硫塔前后、曝气之后海水样品中的汞含量。实验结果为:烟气中的气态汞占总汞的79.1%以上,脱硝催化剂对汞的价态具有强烈的转化作用,烟气中83.4%的气态Hg0被氧化成气态Hg2+;静电除尘对颗粒态汞的去除率几乎达到100%;在脱硫塔中,海水对烟气中汞的洗脱率高达73.6%,曝气后排放前的海水中含汞量是新鲜海水的5.5倍。研究表明锅炉烟气净化设施对汞的排放特性有着重要的影响。In order to study the effect of flue-gas cleaning devices on mercury emission from coal-fired boiler, Ontario-Hydro method had been applied to determine the mercury concentration and speciation in the flue-gas emitted from a 300MW coal-fired boiler, which was equipped with various pollution control devices, including selective catalyst reduction (SCR) De-NOx system, electrostatic precipitator (ESP), and flue-gas seawater De-SO2 system (FGD). Mercury concentration in raw coal, bottom ash and fly ash of the boiler, seawater at the inlet and outlet of SO2 absorption reactor and the drainage of aeration sink, were also analyzed. The results indicate that the percentage of gaseous mercury in total mercury discharged is more than 79.1%. De-NOx catalyst strongly affects the mercury speciation transformation, showing a conversion rate of 83.4% for Hg0 to Hg2+. The removal efficiency of particulate mercury by ESP is close to 100%. With seawater FGD, the removal efficiency of mercury is as high as 73.6%. The mercury concentration in the seawater of drainage from aeration sink is 5.5 times higher than that in fresh seawater. The study shows that the flue-gas cleaning devices in coal-fired power plant play an important role on mercury emission characterization

    基于内毒素血症探讨皂术茵陈方对非酒精性脂肪性肝炎大鼠的影响

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    目的 基于内毒素血症探讨皂术茵陈方防治非酒精性脂肪性肝炎(NASH)大鼠的影响及其作用机制。方法 采用随机数字表法将40只大鼠分为5组,即正常组、模型组、皂术茵陈方组、盐酸吡格列酮组及培菲康组,每组8只。除正常组外,其余32只大鼠采用高脂饮食16周建立大鼠NASH模型,在造模第9周开始,皂术茵陈方组给予皂术茵陈方水提液60 mg/(kg·d)灌胃,盐酸吡格列酮组给予盐酸吡格列酮10 mg/(kg·d)灌胃,培菲康组给予培菲康210 mg/(kg·d)灌胃,正常组及模型组均给予双蒸水10 mL/(kg·d)灌胃,共治疗8周。第16周末经腹主动脉取血,生化法检测肝组织甘油三酯(TG)水平,苏木精—伊红(HE)染色观察肝组织病理学变化。终点显色法检测血浆内毒素(LPS)含量。ELISA法检测肝组织肿瘤坏死因子-α(TNF-α)、白细胞介素(IL)-1β、IL-6等炎症因子的表达水平。结果 与正常组比较,模型组大鼠肝组织显示出典型的NASH组织学特征,出现重度脂肪变性,不同程度的炎细胞浸润和坏死灶。大鼠肝湿重、肝指数、肝脏TG含量、血浆LPS水平、肝组织TNF-α、IL-1β、IL-6等炎症因..
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