A comparison of collocation-based similarity measures in query expansion

In this paper, we present a comparison of collocation-based similarity measures: Jaccard, Dice and Cosine similarity measures for the proper selection of additional search terms in query expansion. In addition, we consider two more similarity measures: average conditional probability (ACP) and normalized mutual information (NMI). ACP is the mean value of two conditional probabilities between a query term and an additional search term. NMI is a normalized value of the two terms' mutual information. All these similarity measures are the functions of any two terms' frequencies and the collocation frequency, but are different in the methods of measurement. The selected measure changes the order of additional search terms and their weights, hence has a strong influence on the retrieval performance. In our experiments of query expansion using these five similarity measures, the additional search terms of Jaccard, Dice and Cosine similarity measures include more frequent terms with lower similarity values than ACP or NMI. In overall assessments of query expansion, the Jaccard, Dice and Cosine similarity measures are better than ACP and NMI in terms of retrieval effectiveness, whereas, NMI and ACP are better in terms of execution efficiency.     

西藏沿阶草属一新种

There are eleven species of Satyrium hitherto reported in China, among which, after a detailed examination of herbarium specimens consisting of about 300 plants, only four forms, represented by S. nepalense D. Don, S. ciliatum Ldl., S. setchuenicum Kranzl. and S. yunnanense Rolfe, are susceptible of division. S. nepalense is a wides- pread species with its main distribution centre in indian region, whereas the other three, with which the present paper deals, are largely distributed in our country.       S. ciliatum is characterized by its pink flowers with spurs about half as long as the ovary.  It is usually found in mountain meadows at an altitude between 1900- 4100m. from Szechuan through Kweichow, Yunnan  and  Tibet,  southwestward  to Sikkim and Bhutan. In all its flowers examined, both female and male organs are perfect and many have produced capsules. It is, no doubt, the hermaphrodite form as seen in the ordinary orchids.       S. setchuenicum closely resembles S. ciliatum in habit, distinguished mainly by having flowers without or with short spurs.  These two forms are sympatric.  In our herbarium, for instance, they are sometimes found on a same specimen or the different sheets with the same field number, such as Y. Tsiang 11454, R. C. Ching 24184, T. P. Wang 9497, etc.  A detailed comparison shows that in S. setchuenicum the anther and pollinia are abortive or even entirely absent, and the stigma is larger than  the rostellum which usually partly thickens and becomes some-what stigma-like, while in S. ciliatum the male organ is well developed, and the thin rostellum is larger. Between these two forms several intermediates are found. It is quite certain that they are dif- ferent sexual forms belonging to one and the same species, and so called S. setchuenic- um is but a female form of S. ciliatum.      Another sympatric form is S. yunnanense, characterized by its yellow flowers with somewhat horizontally extended spurs.  Its anther, pollinia and rostellum are very similar to those of hermaphrodite form of S. ciliatum, but the ovary is narrower and the stigma is usually smaller.  It is interesting to note that in all specimens examined consisting of 36 individuals, no fruit can be found, while in those of S. ciliatum, includ- ing both female and hermaphrodite forms, the lower flowers of the racemes are mostly found to have produced fine seed-capsules. From  these  facts we  may confidently regard this species as the male form of S. ciliatum.      Thus, we have three separate sexual forms in S. ciliatum, to which eight specific names previously recorded in China are here referred. Detailed discussion and descrip- tion as well as a key to the chinese species are given as above. Its geographical distribu- tion is mapped.  The flowers of these three forms are illustrated.  All the specimens cited here, with a few exceptions, are deposited in the herbarium of Institute of Botany,Academia Siaica.     

软件过程标准的比较研究

国际通用的软件过程标准有ISO9000、ISO／IEC12207、CMM、CLEANROOM、ISO／IEC15504、NASA—SEL和BOOTSTRAP等,每种标准都有一定的特点和适用范围。其中CMM尤为广大软件企业推崇。本文以CMM为基础,比较研究了CMM与其它软件过程标准的关系。研究表明：CMM与ISO9000、CLEANROOM、ISO／IEC15504、NASA—SEL和BOOTSTRAP存在直接的紧密关系;ISO／IEC12207与ISO9000和ISO／IEC15504关系密切,并通过二者与CMM间接相关联。     

Institutional entrepreneurship in constructing alternative paths: A comparison of biotech hybrids

This paper investigates how firms adapt their innovation strategies to cope with constraints in national institutional environments. It is a comparative case study of Dutch and British dedicated biotechnology firms focusing on a particular type of strategy, the hybrid model. Patterns of skill accumulation and learning present in the Dutch hybrids are indications of how they use institutional advantages to focus on low-risk innovation and build deeper competences while also pursuing high-risk innovation strategies. The Dutch hybrid model offers insight into how firms comply with the dominant logic of the biotechnology field even when their institutional frameworks encourage the pursuit of low-risk innovation strategies.     

Information retrieval in the workplace: A comparison of professional search practices

Legal researchers, recruitment professionals, healthcare information professionals, and patent analysts all undertake work tasks where search forms a core part of their duties. In these instances, the search task is often complex and time-consuming and requires specialist expertise to identify relevant documents and insights within large domain-specific repositories and collections. Several studies have been made investigating the search practices of professionals such as these, but few have attempted to directly compare their professional practices and so it remains unclear to what extent insights and approaches from one domain can be applied to another. In this paper we describe the results of a survey of a purposive sample of 108 legal researchers, 64 recruitment professionals and 107 healthcare information professionals. Their responses are compared with results from a previous survey of 81 patent analysts. The survey investigated their search practices and preferences, the types of functionality they value, and their requirements for future information retrieval systems. The results reveal that these professions share many fundamental needs and face similar challenges. In particular a continuing preference to formulate queries as Boolean expressions, the need to manage, organise and re-use search strategies and results and an ambivalence toward the use of relevance ranking. The results stress the importance of recall and coverage for the healthcare and patent professionals, while precision and recency were more important to the legal and recruitment professionals. The results also highlight the need to ensure that search systems give confidence to the professional searcher and so trust, explainability and accountability remains a significant challenge when developing such systems. The findings suggest that translational research between the different areas could benefit professionals across domains.     

福建卷柏属植物的物种多样性述评

卷柏属Selaginella Beauv.是一个在分类上较困难的类群,种类多,形态变化大。全世界有卷柏属植物750种以上,可以分为5个亚属。2002年10月我们对武夷山脉及周边地区的卷柏种类进行了调查,采集的标本存放于新加坡国立大学标本馆(SINU)和厦门大学标本馆(AU)。此外,我们还认真观察了来自福建师范大学标本馆(FNU)和AU的卷柏标本。结果表明,在福建,卷柏有18种1变种。其中,缘毛卷柏S. ciliaris、白毛卷柏S. albociliata和布朗卷柏S. braunii是福建分布的3个新记录。     

福建卷柏属植物的物种多样性述评

卷柏属Selaginella Beauv.是一个在分类上较困难的类群,种类多,形态变化大。全世界有卷柏属植物750种以上,可以分为5个亚属。2002年10月我们对武夷山脉及周边地区的卷柏种类进行了调查,采集的标本存放于新加坡国立大学标本馆(SINU)和厦门大学标本馆(AU)。此外,我们还认真观察了来自福建师范大学标本馆(FNU)和AU的卷柏标本。结果表明,在福建,卷柏有18种1变种。其中,缘毛卷柏S. ciliaris、白毛卷柏S. albociliata和布朗卷柏S. braunii是福建分布的3个新记录。