Search (297 results, page 15 of 15)

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16. 1.2016 10:22:28

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16. 1.2016 10:22:28

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Content

Dieser Aufsatz ist kein Abgesang auf MeSH (= Medical Subject Headings in Medline/PubMed), wie man/frau vielleicht vermuten könnte. Vielmehr wird - ohne informatiklastiges Fachchinesisch - an Hand des von der National Library of Medicine entwickelten Unified Medical Language System erklärt, worin die Anforderungen an Ontologien bestehen, die im Zusammenhang mit dem Semantic Web allerorten eingefordert und herbeigewünscht werden. Eine Lektüre für Einsteigerinnen, die zum Vertiefen der gewonnenen Begriffssicherheit an Hand der weiterführenden Literaturhinweise anregt. Da das UMLS hier vor allem als Beispiel verwendet wird, werden auch Bibliothekarlnnen, Dokumentarlnnen und Informationsspezialistinnen anderer Fachbereiche den Aufsatz mit Gewinn lesen - und erfahren, dass unser Fachwissen aus der Sacherschließung und der Verwendung und Mitgestaltung von Normdateien und Thesauri bei der Entwicklung von Ontologien gefragt ist! (Eveline Pipp, Universitätsbibliothek Innsbruck). - Die elektronische Version dieses Artikels ist verfügbar unter: http://www.egms.de/en/journals/mbi/2006-6/mbi000049.shtml.

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Content

Beitrag während: World library and information congress: 74th IFLA general conference and council, 10-14 August 2008, Québec, Canada.

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Abstract

Subject access to information has been the predominant approach of users to satisfy their information needs. Research demonstrates that the integration of controlled vocabulary information with an information retrieval system helps users perform more effective subject searches. This integration becomes possible when subject authority data (information about subjects from authority files) are linked to bibliographic files and are made available to users. The purpose of authority control is to ensure consistency in representing a value-a name of a person, a place name, or a subject term-in the elements used as access points in information retrieval. For example, "World War, 1939-1945" has been established as an authorized subject heading in the Library of Congress Subject Headings (LCSH). When using LCSH, in cataloging or indexing, all publications about World War II are assigned the established heading regardless of whether a publication refers to the war as the "European War, 1939-1945", "Second World War", "World War 2", "World War II", "WWII", "World War Two", or "2nd World War." The synonymous expressions are referred to by the authorized heading. This ensures that all publications about World War II can be retrieved by and displayed under the same subject heading, either in an individual institution's own catalog or database or in a union catalog that contains bibliographic records from a number of individual libraries or databases. In almost all large bibliographic databases, authority control is achieved manually or semi-automatically by means of an authority file. The file contains records of headings or access points - names, titles, or subjects - that have been authorized for use in bibliographic records. In addition to ensuring consistency in subject representation, a subject authority record also records and maintains semantic relationships among subject terms and/or their labels. Records in a subject authority file are connected through semantic relationships, which may be expressed statically in subject authority records or generated dynamically according to the specific needs (e.g., presenting the broader and narrower terms) of printed or online display of thesauri, subject headings lists, classification schemes, and other knowledge organization systems.

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Source

LIBREAS: Library ideas. no.15, 2009, S.23-28

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Content

"One of the things I enjoyed the most when I was a reference librarian was the wide range of questions my clients sent my way. What was the original title of the first Godzilla movie? (Gojira, released in 1954) Who said 'I'm as pure as the driven slush'? (Tallulah Bankhead) What percentage of adults have gone to a jazz performance in the last year? (11%) I have found that librarians, speech writers and journalists have one thing in common - we all need to find information on all kinds of topics, and we usually need the answers right now. The following are a few of my favorite sites for finding answers to those there-must-be-an-answer-out-there questions. - For the electronic equivalent to the "ready reference" shelf of resources that most librarians keep hidden behind their desks, check out RefDesk . It is particularly good for answering factual questions - Where do I get the new Windows XP Service Pack? Where is the 386 area code? How do I contact my member of Congress? - Another resource for lots of those quick-fact questions is InfoPlease, the publishers of the Information Please almanac .- Right now, it's full of Olympics data, but it also has links to facts and factoids that you would look up in an almanac, atlas, or encyclopedia. - If you want numbers, start with the Statistical Abstract of the US. This source, produced by the U.S. Census Bureau, gives you everything from the divorce rate by state to airline cost indexes going back to 1980. It is many librarians' secret weapon for pulling numbers together quickly. - My favorite question is "how does that work?" Haven't you ever wondered how they get that Olympic torch to continue to burn while it is being carried by runners from one city to the next? Or how solar sails manage to propel a spacecraft? For answers, check out the appropriately-named How Stuff Works. - For questions about movies, my first resource is the Internet Movie Database. It is easy to search, is such a popular site that mistakes are corrected quickly, and is a fun place to catch trailers of both upcoming movies and those dating back to the 30s. - When I need to figure out who said what, I still tend to rely on the print sources such as Bartlett's Familiar Quotations . No, the current edition is not available on the web, but - and this is the librarian in me - I really appreciate the fact that I not only get the attribution but I also see the source of the quote. There are far too many quotes being attributed to a celebrity, but with no indication of the publication in which the quote appeared. Take, for example, the much-cited quote of Margaret Meade, "Never doubt that a small group of thoughtful committed people can change the world; indeed, it's the only thing that ever has!" Then see the page on the Institute for Intercultural Studies site, founded by Meade, and read its statement that it has never been able to verify this alleged quote from Meade. While there are lots of web-based sources of quotes (see QuotationsPage.com and Bartleby, for example), unless the site provides the original source for the quotation, I wouldn't rely on the citation. Of course, if you have a hunch as to the source of a quote, and it was published prior to 1923, head over to Project Gutenberg , which includes the full text of over 12,000 books that are in the public domain. When I needed to confirm a quotation of the Red Queen in "Through the Looking Glass", this is where I started. - And if you are stumped as to where to go to find information, instead of Googling it, try the Librarians' Index to the Internet. While it is somewhat US-centric, it is a great directory of web resources."

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Date

20. 3.2004 12:58:22

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Date

22. 1.2010 14:41:24

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Source

Proceedings of the Fourth Workshop on Link Analysis, Counterterrorism, and Security, SIAM Data Mining Conference, Bethesda, MD, 20-22 April, 2006. [http://www.siam.org/meetings/sdm06/workproceed/Link%20Analysis/15.pdf]

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Abstract

Imagine a library containing 25 billion documents but with no centralized organization and no librarians. In addition, anyone may add a document at any time without telling anyone. You may feel sure that one of the documents contained in the collection has a piece of information that is vitally important to you, and, being impatient like most of us, you'd like to find it in a matter of seconds. How would you go about doing it? Posed in this way, the problem seems impossible. Yet this description is not too different from the World Wide Web, a huge, highly-disorganized collection of documents in many different formats. Of course, we're all familiar with search engines (perhaps you found this article using one) so we know that there is a solution. This article will describe Google's PageRank algorithm and how it returns pages from the web's collection of 25 billion documents that match search criteria so well that "google" has become a widely used verb. Most search engines, including Google, continually run an army of computer programs that retrieve pages from the web, index the words in each document, and store this information in an efficient format. Each time a user asks for a web search using a search phrase, such as "search engine," the search engine determines all the pages on the web that contains the words in the search phrase. (Perhaps additional information such as the distance between the words "search" and "engine" will be noted as well.) Here is the problem: Google now claims to index 25 billion pages. Roughly 95% of the text in web pages is composed from a mere 10,000 words. This means that, for most searches, there will be a huge number of pages containing the words in the search phrase. What is needed is a means of ranking the importance of the pages that fit the search criteria so that the pages can be sorted with the most important pages at the top of the list. One way to determine the importance of pages is to use a human-generated ranking. For instance, you may have seen pages that consist mainly of a large number of links to other resources in a particular area of interest. Assuming the person maintaining this page is reliable, the pages referenced are likely to be useful. Of course, the list may quickly fall out of date, and the person maintaining the list may miss some important pages, either unintentionally or as a result of an unstated bias. Google's PageRank algorithm assesses the importance of web pages without human evaluation of the content. In fact, Google feels that the value of its service is largely in its ability to provide unbiased results to search queries; Google claims, "the heart of our software is PageRank." As we'll see, the trick is to ask the web itself to rank the importance of pages.

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Content

Auch das bringt was: Gezielte Plattformwechsel Das versucht auch ein Dienst wie Pandia : Der Metasearcher kombiniert in seinen Anfragen gute Searchengines mit der Vollindexierung qualitativ hochwertiger Inhalte-Angebote. So kombiniert Pandia gezielt die Encyclopedia Britannica, Lexika und Searchengines mit den Datenbeständen von Amazon. Wozu das gut sein soll und kann, zeigt das praktische Beispiel einer sehr sachlich orientierten Suche: "Retina Implant". Dabei geht es um Techniken, über oparative Eingriffe und Implantate an Netzhaut-Degeneration erblindeter Menschen das Augenlicht (zumindest teilweise) wieder zu geben. Pandia beantwortet die Suche zunächst mit dem Verweis auf etliche universitäre und privatwirtschaftliche Forschungsinstitute. 13 von 15 Suchergebnissen sind 100 Prozent relevant: Hier geht es ab in die Forschung. Die letzten beiden verweisen zum einen auf eine Firma, die solche Implantate herstellt, die andere auf einen Fachkongress unter anderem zu diesem Thema: Das ist schon beeindruckend treffsicher. Und dann geht's erst los: Mit einem Klick überträgt Pandia die Suchabfrage auf das Suchmuster "Nachrichtensuche", als Resultat werden Presse- und Medienberichte geliefert. Deren Relevanz ist leicht niedriger: Um Implantate geht es immer, um Augen nicht unbedingt, aber in den meisten Fällen. Nicht schlecht. Noch ein Klick, und die Suche im "Pandia Plus Directory" reduziert die Trefferanzahl auf zwei: Ein Treffer führt zur Beschreibung des universitären "Retinal Implant Project", der andere zu Intelligent Implants, einer von Bonner Forschern gegründeten Firma, die sich auf solche Implantate spezialisiert hat - und nebenbei weltweit zu den führenden zählt. Noch ein Klick, und Pandia versucht, Bücher zum Thema zu finden: Die gibt es bisher nicht, aber mit Pandias Hilfe ließe sich sicher eins recherchieren und schreiben. Trotzdem: Keiner der angesprochenen Dienste taugt zum Universalwerkzeug. Was der eine kann, das schafft der andere nicht. Da hilft nur ausprobieren. Der Suchdienst muss zum Sucher passen. Fazit und Ausblick So gut Google auch ist, es geht noch besser. Die intelligente Kombination der besten Fertigkeiten guter Suchwerkzeuge schlägt selbst den Platzhirsch unter den Suchdiensten. Doch darum geht es ja gar nicht. Es geht darum, die Suche im Web effektiv zu gestalten, und das will nach wie vor gelernt sein. Noch einfacher und effektiver geht das mit zahlreichen, oft kostenlosen Werkzeugen, die entweder als eigenständige Software (Bots) für Suche und Archivierung sorgen, oder aber als Add-On in den heimischen Browser integriert werden können. Doch dazu mehr im zweiten Teil dieses kleinen Web-Wanderführers"

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Content

"The Internet is often likened to an organic entity and this analogy seems particularly appropriate in the light of some striking new visualizations of the complex mesh of Internet pathways. The images are results of a new graph visualization tool, code-named Walrus, being developed by researcher, Young Hyun, at the Cooperative Association for Internet Data Analysis (CAIDA) [1]. Although Walrus is still in early days of development, I think these preliminary results are some of the most intriguing and evocative images of the Internet's structure that we have seen in last year or two. A few years back I spent an enjoyable afternoon at the Monterey Bay Aquarium and I particularly remember a stunning exhibit of jellyfish, which were illuminated with UV light to show their incredibly delicate organic structures, gently pulsing in tanks of inky black water. Jellyfish are some of the strangest, alien, and yet most beautiful, living creatures [2]. Having looked at the Walrus images I began to wonder, perhaps the backbone networks of the Internet look like jellyfish? The image above is a screengrab of a Walrus visualization of a huge graph. The graph data in this particular example depicts Internet topology, as measured by CAIDA's skitter monitor [3] based in London, showing 535,000-odd Internet nodes and over 600,000 links. The nodes, represented by the yellow dots, are a large sample of computers from across the whole range of Internet addresses. Walrus is an interactive visualization tool that allows the analyst to view massive graphs from any position. The graph is projected inside a 3D sphere using a special kind of space based hyperbolic geometry. This is a non-Euclidean space, which has useful distorting properties of making elements at the center of the display much larger than those on the periphery. You interact with the graph in Walrus by selecting a node of interest, which is smoothly moved into the center of the display, and that region of the graph becomes greatly enlarged, enabling you to focus on the fine detail. Yet the rest of the graph remains visible, providing valuable context of the overall structure. (There are some animations available on the website showing Walrus graphs being moved, which give some sense of what this is like.) Hyperbolic space projection is commonly know as "focus+context" in the field of information visualization and has been used to display all kinds of data that can be represented as large graphs in either two and three dimensions [4]. It can be thought of as a moveable fish-eye lens. The Walrus visualization tool draws much from the hyperbolic research by Tamara Munzner [5] as part of her PhD at Stanford. (Map of the Month examined some of Munzner's work from 1996 in an earlier article, Internet Arcs Around The Globe.) Walrus is being developed as a general-purpose visualization tool able to cope with massive directed graphs, in the order of a million nodes. Providing useful and interactively useable visualization of such large volumes of graph data is a tough challenge and is particularly apposite to the task of mapping of Internet backbone infrastructures. In a recent email Map of the Month asked Walrus developer Young Hyun what had been the hardest part of the project thus far. "The greatest difficulty was in determining precisely what Walrus should be about," said Hyun. Crucially "... we had to face the question of what it means to visualize a large graph. It would defeat the aim of a visualization to overload a user with the large volume of data that is likely to be associated with a large graph." I think the preliminary results available show that Walrus is heading in right direction tackling these challenges.

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Date

24.10.2008 14:19:22

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Content

The View From Above Browsing for a particular piece on information on the Web can often feel like being stuck in an unfamiliar part of town walking around at street level looking for a particular store. You know the store is around there somewhere, but your viewpoint at ground level is constrained. What you really want is to get above the streets, hovering half a mile or so up in the air, to see the whole neighbourhood. This kind of birds-eye view function has been memorably described by David D. Clark, Senior Research Scientist at MIT's Laboratory for Computer Science and the Chairman of the Invisible Worlds Protocol Advisory Board, as the missing "up button" on the browser [3] . ET-Map is a nice example of a prototype for Clark's "up-button" view of an information space. The goal of information maps, like ET-Map, is to provide the browser with a sense of the lie of the information landscape, what is where, the location of clusters and hotspots, what is related to what. Ideally, this 'big-picture' all-in-one visual summary needs to fit on a single standard computer screen. ET-Map is one of my favourite examples, but there are many other interesting information maps being developed by other researchers and companies (see inset at the bottom of this page). How does ET-Map work? Here is a sequence of screenshots of a typical browsing session with ET-Map, which ends with access to Web pages on jazz musician Miles Davis. You can also tryout ET-Map for yourself, using a fully working demo on the AI Lab's website [4] . We begin with the top-level map showing forty odd broad entertainment 'subject regions' represented by regularly shaped tiles. Each tile is a visual summary of a group of Web pages with similar content. These tiles are shaded different colours to differentiate them, while labels identify the subject of the tile and the number in brackets telling you how many individual Web page links it contains. ET-Map uses two important, but common-sense, spatial concepts in its organisation and representation of the Web. Firstly, the 'subject regions' size is directly related to the number of Web pages in that category. For example, the 'MUSIC' subject area contains over 11,000 pages and so has a much larger area than the neighbouring area of 'LIVE' which only has 4,300 odd pages. This is intuitively meaningful, as the largest tiles are visually more prominent on the map and are likely to be more significant as they contain the most links. In addition, a second spatial concept, that of neighbourhood proximity, is applied so 'subject regions' closely related in term of content are plotted close to each other on the map. For example, 'FILM' and 'YEAR'S OSCARS', at the bottom left, are neighbours in both semantic and spatial space. This make senses as many things in the real-world are ordered in this way, with things that are alike being spatially close together (e.g. layout of goods in a store, or books in a library). Importantly, ET-Map is also a multi-layer map, with sub-maps showing greater informational resolution through a finer degree of categorization. So for any subject region that contains more than two hundred Web pages, a second-level map, with more detailed categories is generated. This subdivision of information space is repeated down the hierarchy as far as necessary. In the example, the user selected the 'MUSIC' subject region which, not surprisingly, contained many thousands of pages. A second-level map with numerous different music categories is then presented to the user. Delving deeper, the user wants to learn more about jazz music, so clicking on the 'JAZZ' tile leads to a third-level map, a fine-grained map of jazz related Web pages. Finally, selecting the 'MILES DAVIS' subject region leads to more a conventional looking ranking of pages from which the user selects one to download.
Research Prototypes Visual SiteMap Developed by Xia Lin, based at the College of Library and Information Science, Drexel University. CVG Cyberspace geography visualization, developed by Luc Girardin, at The Graduate Institute of International Studies, Switzerland. WEBSOM Maps the thousands of articles posted on Usenet newsgroups. It is being developed by researchers at the Neural Networks Research Centre, Helsinki University of Technology in Finland. TreeMaps Developed by Brian Johnson, Ben Shneiderman and colleagues in the Human-Computer Interaction Lab at the University of Maryland. Commercial Information Maps: NewsMaps Provides interactive information landscapes summarizing daily news stories, developed Cartia, Inc. Web Squirrel Creates maps known as information farms. It is developed by Eastgate Systems, Inc. Umap Produces interactive maps of Web searches. Map of the Market An interactive map of the market performance of the stocks of major US corporations developed by SmartMoney.com."

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Date

10. 9.2006 17:22:54

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Source

http://www.miskatonic.org/library/facet-biblio.html