Review of galactic and extragalactic searches for class I methanol masers

Class I methanol masers are important tools for investigations of star formation throughout the Universe. Recently, a series of surveys for class I methanol masers at the 95 GHz transition toward samples of young stellar objects have been undertaken. These surveys have resulted in the detection of about 200 new class I methanol masers and combined with previous increased the number of known observations they have class I methanol masers in our Galaxy to ~400. From analysis of the relationship between class I methanol maser emission and associated astrophysical objects, it has been shown that the intensity of the class I methanol maser emission is closely correlated with the properties of the 1.1 mm Bolocam Galactic Plane Survey （BGPS） dust continuum sources and outflow properties. This further supports the hypothesis that class I methanol masers are collisionally pumped and excited in shocked regions. Based on these observations, it can be inferred that the BGPS catalog is likely to provide more reliable samples for targeting further class I methanol maser searches. A new survey for class I methanol masers toward a larger size sample of BGPS sources to test this is currently underway. The prospects for detecting class I methanol megamasers in extragalactic sources is discussed, and observations constituting the first sensitive search have been proposed.     

Scalable manufacturing methodologies for improving adeno-associated virus-based pharmaprojects

Adeno-associated virus （AAV） is a promising viral vector and meets most requirements of being a safe biological agent. However, the commercialization of AAV has been hampered due to the limitation of large-scale production, and only a small number of clinical trials have been launched. In recent years, progresses in scalable manufacturing of AAV have dramatically improved AAV- based clinical researches, and have assisted the develop- ment of investigational drug products. An AAVl-based investigational product, Glybera, has been formally approved by European Commission for the treatment of lipoprotein lipase deficiency （LPLD）. Glybera was the first gene therapy product in the western world, and the pro- duction process involves a scalable baculovirus-insect cell system. However, many problems still need to be solved to improve the productivity and quality of AAV. The present review gives critical insights into current state-of-the-art scalable producing methodologies of AAV, such as bacu-lovirus-insect cell system, HSV complementation system, and Ad complementation system, along with a discussion on the problems, solutions, and developmental trends.Novel AAV-producing platforms in Saccharomyces cere- visiae and vaccinia virus complementation system will also be discussed.     

Multifractal analysis of resting state fMRI series in default mode network: age and gender effects

Age-related changes of resting state in default mode network （DMN） may provide new clues to the developing mechanism of normal brain as well as early diagnosis and therapy of some neuropsychiatric disorders. The application of multifractal theory to functional magnetic resonance imaging （fMRI） signals has recently raised increasing attention. We aim to explore the multifractal characteristics underlying the resting state functional magnetic resonance imaging （rs-fMRI） series extracted from DMN, and two issues are mainly discussed： （1） whether there exist multifractals in rs-fMRI series; （2） whether it is possible to distinguish between the different ages or genders by means of multifractal characteristics. Results demon- strated the existence of multifractals in rs-fMRI series in DMN. In addition, slight differences between young subjects and middle-aged or elderly subjects can be successfully detected by △asα, a modified measure we proposed. Furthermore, it is revealed that the rs-fMRI series from young subjects possess smaller averaged scale index and weaker long range correlation, while those from middle-aged or elderly people present increasing averaged scale index andstronger long range correlation. Whereas no significant statistical differences has been found between male and female group. Our results, therefore, highlight the potential useful- ness of multifractal analysis in fMRI series of a certain brain region, and provide important insights into healthy aging in DMN.     

投稿须知

<正>《青海师范大学学报(自然科学版)》是经国家新闻出版署批准,国内外公开发行的综合性学术刊物。主要刊登数学、物理、计算机、化学、生物、地理、体育及相关学科的学术论文。本刊对来稿有如下要求:1.投稿信箱:xuebao@qhnu.edu.cn2.来稿结构顺序:篇名、作用署名、工作单位、所在城市及邮编、摘要(200字以内)、关键词(3~8个)、中     

半群H_n的每个星理想的秩和幂等元秩

设H n是自然序集X n={1,2,3,…,n}(n≥3)上的保降序且保序有限奇异变换半群,记H(n,r)={α∈H n:|Imα|≤r}为半群H n的双边星理想.对1≤r≤n-1,刻划了H(n,r)是由秩为r的幂等元生成的且它的秩和幂等元秩都等于Cr-1n-1.进一步证明了当l=r时,r(H(n,r),H(n,l))=0且当1≤lr时,r(H(n,r),H(n,l))=Cr-1n-1.     

常利率复合二项风险模型的破产概率分布

研究了含利率因素的复合二项双险种风险模型的破产问题,获得了该模型下破产概率和生存概率的递推式以及所满足的积分方程.     

时域光学拓扑成像方法的模拟和实验研究

针对现有的以修正的朗伯-比尔定律(modified Lambert-Beer law,MLBL)为理论模型的光学拓扑方法存在量化度不准确的问题,提出了一种基于最小二乘拟合算法的时域光学拓扑成像方法.该方法利用时域扩散方程在半无限空间条件下的解析解和测量曲线实现最佳匹配以计算相邻的源点与探测点之间的待测组织吸收系数变化值.对该时域光学拓扑成像方法进行了一系列的模拟验证,并以基于时间相关单光子计数(time-correlated single photon counting,TCSPC)技术的多通道时间分辨测量系统为平台进行了实验验证.结果表明:所提出的最小二乘拟合算法总体上优于传统的基于经验值光程的MLBL方法.     

用3D打印“智”造生活

<正>近日,一份名为《2013年浙江省3D打印产业发展报告》的文件在浙江省3D打印产业联盟单位内部工作人员手中传阅。2013年是浙江省3D打印产业发展的元年,省3D打印产业联盟成立,联盟成员迅速扩展。有数据表明,与3D打印相关的产业发展迅猛,其中涉及装备开发的企业有9家、材料开发企业5家、软件开发企业3家、应用服务企业28家,浙     

基于属性相关的朴素贝叶斯分类算法

朴素贝叶斯分类器是一种简单、高效的分类算法,它以贝叶斯定理和最大后验假设为理论基础,然而朴素贝叶斯分类器属性之间相互独立的假设,影响了朴素贝叶斯分类器的性能.提出先使用基于相关的属性选择算法进行属性选择,然后在选择的属性集上,用朴素贝叶斯分类器对数据集进行分类.实验证明,与未使用属性选择的实验结果相比,使用基于相关的属性选择算法进行属性选择后,朴素贝叶斯分类器平均分类正确率提高,分类效率显著提升.     

具反应扩散项和马尔可夫跳变的时滞耦合神经网络的同步

研究了一类具有反应扩散项的时滞耦合神经网络的同步问题．通过构造Lyapunov—Krasovskii泛函,利用线性矩阵不等式技术并结合Kronecker积获得了耦合神经网络依赖T-he滞和反应扩散算子的均方全局指数同步的充分性判据．此外,将细胞激活函数假设为扇形非线性函数,能减少结论的保守性,数值仿真结果证明所得结论有效．