Grundlagen des Burrows-Wheeler-Kompressionsalgorithmus

Der Burrows-Wheeler-Kompressionsalgorithmus hat als ein universelles Kompressionsverfahren in den letzten Jahren aufgrund seiner hervorragenden Kompressionsraten und hohen Verarbeitungsgeschwindigkeiten eine bemerkenswerte Beachtung erfahren. Das Herzstück des Algorithmus stellt die sogenannte Burrows-Wheeler-Transformation dar. Es handelt sich bei dieser Transformation um eine Permutation der Eingabedaten, welche Zeichen mit ähnlichem Kontext nahe beieinander anordnet. Die Transformation sowie die zugehörige Rücktransformation werden zusammen mit den weiteren Stufen des Algorithmus in einer gegenüber der Standardversion verbesserten Variante vorgestellt und die Ergebnisse mit denen anderer Datenkompressionsalgorithmen verglichen.     

Scholarly communication trends — voices from the vortex: a summary of specialist opinion

The views of specialists (academics, librarians, publishers and information scientists) on trends in scholarly communications were canvassed by means of structured questions. A greater commonality of views was found than might have been expected.     

Organizational Power and the Institutional Review Board

In this essay, we respond to the narratives and essays in this issue by examining organizational power issues related to researchers and institutional research boards (IRBs). Rather than taking a singular perspective on power, we use multiple perspectives and suggest that the cumulative analyses provide the best understanding of IRBs and organizational power.     

Editorial zum Themenheft: ?‘Software-Reengineering“’

Ohne Zusammenfassung     

Validating the Willingness to Self-Censor Scale: Individual Differences in the Effect of the Climate of Opinion on Opinion Expression

Hayes, Glynn, and Shanahan (2005) defined self-censorship asthe withholding of one’s opinion around an audience perceivedto disagree with that opinion. They argued that people differin their willingness to self-censor and introduced an 8-itemself-report instrument, the Willingness to Self-Censor scale,to measure this individual difference. The results of an experimentalstudy presented here provide further evidence of the constructvalidity of the scale. Each participant in the study was presentedwith a hypothetical scenario that contained information suggestinga group of people the participant was conversing with abouta controversial topic held opinions that were either uniformlysimilar to or different from the participant’s own opinion.Four weeks prior, each participant had responded to the Willingnessto Self-Censor scale and a measure of dispositional shyness.As expected, the manipulation of the climate of opinion affectedwillingness to express an opinion to the group, but more soamong those who scored relatively high on the Willingness toSelf-Censor scale. These results support the notion that somepeople rely on information about the climate of opinion moreso than do others when they decide whether or not to voice theiropinion publicly, and they suggest that the Willingness to Self-Censorscale measures this individual difference.     

State of the art of expert searching: results of a Medical Library Association survey.

OBJECTIVES: Medical Library Association (MLA) members were surveyed to gather background about the current state of expert searching in institutions. The survey results were intended to guide the recommendations of the Task Force on Expert Searching for promoting the importance of expert searching and implementing those recommendations. METHODS: MLA members were surveyed, and data obtained from the survey were compiled and analyzed to answer three general questions: what is the perceived value of searching skills to the institution, how do health sciences librarians maintain and improve their searching skills, and how are searching services promoted and/or mandated in the institution. RESULTS: There were 256 responses to the survey. Over 95% of the respondents saw their expert-searching skills were of value to their institutions, primarily through performing mediated searches and search consultations. Over 83% of the respondents believed that their searching skills had improved over the past 10 years. Most indicated that continued training was very important in maintaining and improving their skills. Respondents promoted searching services most frequently through orientations, brochures, and the libraries' Web pages. No respondent's institution mandated expert searching. Less than 2% of respondents' institutions had best practice guidelines related to expert searching, and only about 8% had guidelines or policies that identified situations where expert searching was recommended. CONCLUSIONS: The survey supports the belief that health sciences librarians still play a valuable role in searching, particularly in answering questions about treatment options and in providing education. It also highlights the need for more expert searching courses. There has been minimal discussion about the perceived need for expert-searching guidelines in the institutions represented by survey respondents.     

Consolidation of Black-dyed Māori Textile Artefacts: Evaluating the Efficacy of Sodium Alginate

Black-dyed artefacts are found in museums worldwide, many produced using an iron-tannate compound. Deterioration of iron-tannate dyed artefacts is an international preservation issue: in New Zealand the deterioration of paru (iron-tannate) dyed Māori textiles is widespread. This article reports experimental work testing the efficacy of sodium alginate, a consolidant developed for deteriorated paru-dyed muka (fibre from harakeke; Phormium tenax). The colour stability, strength retention, and acidity of paru-dyed muka consolidated with sodium alginate (0.25, 0.5, and 1% w/v in water) was tested pre- and post-artificial light ageing. This study found that sodium alginate had no negative effect on paru-dyed muka and in some cases provided benefit. Interestingly, the colour of paru-dyed muka is substantially more stable in UV-filtered light than previously recognised. Also microfading results were in agreement with visual assessments of colour change at 1 Mlux hour exposure, providing confidence in this relatively new technique to assess colour change.     

Google Scholar's Coverage of the Engineering Literature 10 years Later

In 2008 Meier and Conkling first tested Google Scholar's coverage of the engineering literature against citations gathered from the Compendex database. Since that time, other studies have used the same methodology and found improvement in Google Scholar's coverage. This study uses engineering dissertations from Proquest Dissertations & Theses to create a data set of citations for the comparison of fee-based databases, Compendex and Scopus, against Google Scholar. From 1950 to 2017 Google Scholar outperformed both Compendex and Scopus in discoverability of citations in nine engineering subjects. These results have implications for collection management and information literacy program planning for librarians.