无比对的生物分子序列比较方法

生物序列分析是生物信息学的主要研究领域,常常通过比较分析获取有用的信息。最常用的比较方法是序列比对,但是利用比对的序列比较假设了同源片断之间是邻接保守的,这和遗传重组相冲突,而且多序列比对在计算复杂性等方面存在困难,这些使得人们努力研究无比对的序列比较方法。本文综述了目前无比对序列比较的两类主要方法:一类基于字(低聚物)的出现率及其分布,通过出现率向量定义的笛卡尔空间中的距离计算来实现序列比较;另一类使用柯尔莫哥洛夫复杂度理论或混沌理论来实现序列比较。     

充血性心力衰竭患者二尖瓣叶接合点与二尖瓣环平面距离增加的相关因素分析及临床价值

目的测定二尖瓣叶接合点与二尖瓣环平面之间的距离(CPMA),探讨充血性心力衰竭患者CPMA增加与左心室功能不全之间的相关因素.方法研究对象为78例充血性心力衰竭(CHF)患者和30例正常对照者,分别在基础和实验条件下常规应用超声心动图技术测定各组左室舒张末内径(EDD)、收缩末内径(ESD)、二尖瓣E点至室间隔收缩最高点的垂直距离(EPSS)、并计算左室射血分数(LVEF)、左室短轴缩短率(FS)、二尖瓣环直径(MAD)和CPMA,评价在不同条件下CPMA的变化特点及临床价值.结果 CHF组与正常对照组比较EDD、ESD、EPSS、MAD及CPMA均显著增大,而LVEF、FS显著降低(P＜0.001);经相关分析表明CPMA依次与EDD、ESD及MAD呈线性正相关(r=0.58、0.59及0.53,P＜0.001),与左室收缩功能指标如EPSS呈线性正相关(r=0.48,P＜0.001),却与LVEF及FS呈线性负相关(r=-0.46及-0.44,P＜0.001).多巴酚丁胺可使CPMA由 (12.14±3.46) mm降至 (8.87±2.67) mm,LVEF由 (27.16±6.37) %增加至 (34.12±6.48) %,并且CPMA与LVEF之间呈线性负相关关系(r=-0.72,P＜0.001).抬高下肢后CPMA由 (13.16±3.24) mm降至(10.13±2.66) mm,LVEF由 (31.68±9.46) %增加至 (39.18±8.57) %,FS亦增加;而EPSS和MAD却降低.经单变量分析CPMA>9 mm,MAD>31 mm,LVEF<35%可作为判断NYHA III～IV级的可靠而敏感的指标(P＜0.001).而多变量分析CPMA显著增大和LVEF的显著降低可作为心源性猝死的独立预报因子.结论 CPMA的测定不受心脏节律的影响,在所有CHF患者中容易获得,它不仅能反映心脏收缩功能状态和评价二尖瓣返流的严重程度;而且对评价临床疗效及预后判断都有重要价值.     

Using mental tasks transitions detection to improve spontaneous mental activity classification

This paper presents an algorithm based on canonical variates transformation (CVT) and distance based discriminant analysis (DBDA) combined with a mental tasks transitions detector (MTTD) to classify spontaneous mental activities in order to operate a brain-computer interface working under an asynchronous protocol. The algorithm won the BCI Competition III--Data Set V: Multiclass Problem, Continuous EEG--achieving an averaged classification accuracy over three subjects of 68.65% (79.60, 70.31 and 56.02%, respectively) in a three-class problem.     

远程护理教育的实施与评估

对在国内首次服务于护理教育的远程教育网络作全面考察并评估，用自行设计的调查表，对与远程教学课程传输有关的各类人员（包括管理者，授课教师，技术人员，学历教育和继续教育学员）进行询问调查，结果：学历教育学员对远程教育大部分指标的评价均达到中等或满意以上，对教师的评定和各门课程的满意度均达到满意以上，但远程组满意程度低于医科大学组，86．0％以上的继续教育学员认为：远程教育增强了继续教育的机会，远程教学内容新，容易理解，对护理知识的积累和护理技能的提高帮助。93．4％教师认为远程教学与课堂教学质量无差别，89．9％的被调查者对远程教育表示支持。而在师生互动交流，声音图像传输，板书效果等方面遇到一些挑战，有待进一步改进，结论：远程护理教育在国内的首次实施效果颇佳，提示应加强各部门之间的协调与合作，尽快提高各类人员运用远程设备的能力，使远程护理教育网络在护理人员的学历和继续教育中发挥更大的作用。     

钛种植体表面早期成骨方式的动物模型研究

目的：研究适合用于观察钛种植体表面早期成骨方式的动物模型。方法对原有的种植体植入模式进行改进,使种植体植入动物体内的初始状态为种植体外螺纹贴于种植窝骨壁,种植体螺纹内部与周围骨壁保持一定距离。4只Beagle犬下颌骨延期植入20枚种植体,植入后2周和4周分别处死2只Beagle犬,对标本进行组织学观察。结果4只Beagle犬手术创口均达到一期愈合,未出现种植体松动。组织学观察可见种植体表面新骨生成,种植体周围骨壁新骨生成,可清楚地观察到新骨生成方向,可观察到接触成骨和距离成骨。结论本研究创建的动物模型可以清晰地观察钛种植体表面早期成骨的方式,也可客观地反映种植体表面性能对其表面早期成骨方式的影响。     

海员的深度知觉研究

目的 对海员的深度知觉进行测评，为制定海员选拔标准提供依据。方法 采用深度知觉测试仪对245名海员和87名航海专业学员的深度知觉进行测试。结果 深度知觉对于海员具有很好的鉴别力：不同年龄、工龄、海龄组之间海员深度知觉差异不显著；不同职务、来源和文化程度的海员深度知觉差异不显著；在职海员的深度知觉好于航海专业学员。结论 海员的深度知觉是一稳定的认知能力指标，作为海员的选拔指标是合适的，对于在职海员与学员的评价应有不同要求。     

Focused visual attention distorts distance perception away from the attentional locus

Several lines of evidence show that visual perception is altered at the locus of visual attention: detection is faster, performance better and spatial resolution increased. It is however not known whether attention can affect visual perception further away from its locus. In the present study, we specifically question whether and how visual attention influences spatial perception away from its locus, independently from any saccadic preparation. We use a landmark task in which subjects have to estimate the location of a bisection stimulus relative to two landmark stimuli 15° apart, while fixating one of them. This task is combined with a highly demanding discrimination task performed on one of the two landmarks. This allows us to test for the effect of spatial attention allocation on distance perception, as measured by the subject estimation of the landmarks midpoint. We show that the estimated midpoint is displaced towards the attentional locus, both when attention is instructed on the central landmark or on the peripheral landmark. These results suggest an overrepresentation of space around the attentional locus that can affect perception up to 8° away, and question the existence of an objective spatial representation. They are in line with reports of spatial distortion in hemineglect patients while they strikingly contrast with the spatial compression reported around the time of saccadic execution.     

Location of Early Colorectal Cancers at Fold-Top May Reduce the Risk of Lymph Node Metastasis

Purpose This study was designed to look for significant correlations between location of early colorectal cancer, distance from muscularis mucosae to muscularis propria, and the frequency of lymph node metastasis. Methods A total of 166 early colorectal cancers, including 67 surgically resected lesions, were evaluated. The cancers were divided into two groups: metastatic and nonmetastatic. Cancer lesions were further subtyped at the fold-top or fold-bottom. Macroscopic classifications and histology were performed. Absolute invasive depth and distance from muscularis mucosae to muscularis propria was measured. Multivariate analysis was used to assess relationships among the variables. Results The percentage of polypoid cancer lesions at fold-bottom was higher than at fold-top (74.5 vs. 51.8 percent), whereas flat-type cancer lesions at fold-bottom occurred less often than at fold-top (8.2 vs. 30.4 percent). Logistic regression showed that deep absolute invasive depth, lymphatic and vessel invasion, and cancer location (at fold-bottom) were the significant risk factors for early colorectal cancers leading to lymph-node metastasis. The distance from muscularis mucosae to muscularis propria with lymph-node metastasis (1,396.7 ± 728.4 μm) was shorter than without lymph-node metastasis (3,533.9 ± 2,507.8 μm; P < 0.01). Multivariate analysis showed that distance from muscularis mucosae to muscularis propria was a statistically significant factor for early colorectal cancers leading to lymph node metastasis (P = 0.0054). Conclusions We conclude that early colorectal cancers at the fold-top or with a long distance from muscularis mucosae to muscularis propria have less tendency to metastasize to lymph nodes. Clinically, these results provide evidence of a new indicator of endoscopic mucosal resection for early colorectal cancers at the fold-top.