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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

La Conception et la réalisation d'un concordancier électronique pour l'arabe

Abbes, Ramzi Hassoun, Mohamed Dichy, Joseph January 2006 (has links)
Thèse doctorat : Science de l'Information : Villeurbanne, INSA : 2004. / Cette thèse est composée de 2 vol. ( 1 pour la thèse et 1 pour les annexes) reliés en un seul. Titre provenant de l'écran-titre. Bibliogr. p. [218]-232.
2

Corpus numériques et production écrite en langue étrangère. Une recherche avec des apprenants d'allemand

Schaeffer-Lacroix, Eva 28 November 2009 (has links) (PDF)
Cette thèse en didactique des langues étrangères montre le potentiel des corpus pour l'apprentissage de l'allemand au collège. Conformément aux objectifs poursuivis dans une recherche-action, elle renseigne sur l'évolution des acteurs impliqués dans un dispositif spécifique, en tenant compte de facteurs multiples, tels que le type d'input, les outils, les modes de travail - en présentiel et à distance - et la relation pédagogique. J'ai observé les effets d'un scénario pédagogique, basé sur l'exploitation de corpus spécialisés pour la création de textes du domaine du tourisme. Les participants, des adolescents de niveau intermédiaire en allemand, langue étrangère, ont exploré les corpus à l'aide de lignes de concordances. J'ai analysé leurs discours et leurs actions face à l'input, et j'ai décrit l'évolution de certains aspects linguistiques et discursifs de leurs textes. Le projet et les outils proposés ont soutenu le développement de modes de lecture qui ont favorisé la recherche ciblée d'informations dans l'input. Le recyclage d'éléments repérés dans l'input a mené, pour une partie des apprenants, à l'obtention de productions écrites dont les caractéristiques linguistiques et discursives sont proches de celles attestées dans les corpus. L'écriture intertextuelle a permis aux participants, à des degrés variables, de se décentrer et de progresser dans l'apprentissage de l'altérité. L'observation de formes linguistiques à l'aide de lignes de concordances et l'intégration de collocations identifiées dans l'input ont contribué au développement du système linguistique, en particulier dans le domaine de la flexion des adjectifs.
3

Metrics of positive scalar curvature and generalised Morse functions /

Walsh, Mark, January 2009 (has links)
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 163-164) Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.
4

Metrics of positive scalar curvature and generalised Morse functions

Walsh, Mark, 1976- 06 1900 (has links)
x, 164 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / We study the topology of the space of metrics of positive scalar curvature on a compact manifold. The main tool we use for constructing such metrics is the surgery technique of Gromov and Lawson. We extend this technique to construct families of positive scalar curvature cobordisms and concordances which are parametrised by Morse functions and later, by generalised Morse functions. We then use these results to study concordances of positive scalar curvature metrics on simply connected manifolds of dimension at least five. In particular, we describe a subspace of the space of positive scalar curvature concordances, parametrised by generalised Morse functions. We call such concordances Gromov-Lawson concordances. One of the main results is that positive scalar curvature metrics which are Gromov-Lawson concordant are in fact isotopic. This work relies heavily on contemporary Riemannian geometry as well as on differential topology, in particular pseudo-isotopy theory. We make substantial use of the work of Eliashberg and Mishachev on wrinkled maps and of results by Hatcher and Igusa on the space of generalised Morse functions. / Committee in charge: Boris Botvinnik, Chairperson, Mathematics; James Isenberg, Member, Mathematics; Hal Sadofsky, Member, Mathematics; Christopher Phillips, Member, Mathematics; Michael Kellman, Outside Member, Chemistry
5

Corpus numériques et production écrite en langue étrangère. Une recherche avec des apprenants d'allemand / Electronic corpora and learning to write in a foreign language. A research with learners of German

Schaeffer-Lacroix, Eva 28 November 2009 (has links)
Cette thèse en didactique des langues étrangères montre le potentiel des corpus pour l'apprentissage de l'allemand au collège. Conformément aux objectifs poursuivis dans une recherche-action, elle renseigne sur l'évolution des acteurs impliqués dans un dispositif spécifique, en tenant compte de facteurs multiples, tels que le type d'input, les outils, les modes de travail - en présentiel et à distance - et la relation pédagogique. J'ai observé les effets d'un scénario pédagogique, basé sur l'exploitation de corpus spécialisés pour la création de textes du domaine du tourisme. Les participants, des adolescents de niveau intermédiaire en allemand, langue étrangère, ont exploré les corpus à l'aide de lignes de concordances. J'ai analysé leurs discours et leurs actions face à l'input, et j'ai décrit l'évolution de certains aspects linguistiques et discursifs de leurs textes. Le projet et les outils proposés ont soutenu le développement de modes de lecture qui ont favorisé la recherche ciblée d'informations dans l'input. Le recyclage d'éléments repérés dans l'input a mené, pour une partie des apprenants, à l'obtention de productions écrites dont les caractéristiques linguistiques et discursives sont proches de celles attestées dans les corpus. L'écriture intertextuelle a permis aux participants, à des degrés variables, de se décentrer et de progresser dans l'apprentissage de l'altérité. L'observation de formes linguistiques à l'aide de lignes de concordances et l'intégration de collocations identifiées dans l'input ont contribué au développement du système linguistique, en particulier dans le domaine de la flexion des adjectifs. / This action-research in applied linguistics investigates the evolution of adolescent learners of German as a foreign language during a project involving corpus exploration. It focuses on the role played by resources, tools, face-to-face learning versus distance learning and by the pedagogical relationship. My research analyzes how the learners perceived and exploited three small specialized corpora containing texts representing each one sub-genre of the « tourist information » genre. The learners explored them by means of concordance lines. Firstly, I observe what the learners said about the input and what they did with it. Secondly, I describe how the language and the discourse used in the texts changed during the project. The tasks and tools of the project helped some of the learners to develop reading habits which focus on information retrieval more than on complete comprehension of the text. The effects are texts written in a German ha! ving linguistic features that resemble those attested in the explored corpora. The intertextual writing method offered by the project supports acculturation to the foreign language. By means of concordancing and the import of collocations, the learners are now able to deal with some language features, especially with the domain of German adjective inflection, better than before.
6

La relation gestes-parole dans la planification de la résolution du problème de la Tour de Hanoï chez des enfants, adolescents et adultes colombiens / The gesture-speech relationship in planning the solving of the Tower of Hanoï problem by Columbian children, adolescents and adults

Moreno Torres, Mayilin 09 December 2014 (has links)
Lorsque nous parlons, nous bougeons nos mains, nous faisons des gestes. Les gestes aident à communiquer avec les autres mais aussi à mieux exprimer notre pensée. Les gestes et la parole sont donc deux dimensions qui s’intègrent dans un système de communication unifié, reposant sur des représentations cognitives communes : quand un locuteur produit un message, la plupart des informations qu’il veut partager est certes véhiculée par le discours, mais également par les gestes (McNeil, 1992). Parfois, cette information entre les gestes et la parole est non-concordante. Garbert et Goldin-Meadow (2002) ont montré que lorsque les participants expliquent leur résolution de la tâche de la Tour de Hanoï, ces non-concordances entre l’information transmise par les gestes et celle transmise par la parole, peuvent se produire soit aux moments incertains, preuve que les participants hésitent entre plusieurs stratégies de résolution soit aux moments-clés, indiquant la capacité à planifier deux stratégies de résolution, l’une par les gestes, l’autre par la parole. La planification à travers les « mismatches » gestes-parole n’a pas été étudié malgré les nombreuses recherches de Goldin-Meadow à ce sujet. Nous avons mené une étude en Colombie auprès de 144 participants issus de deux milieux socio-économiques contrastés. Nous avons tenté de combler cette lacune en étudiant les effets de l’âge, du milieu socio-économique et de la complexité de la tâche de la Tour de Hanoï sur les non-concordances gestes-paroles lors des explications anticipant sa résolution. Nos résultats suggèrent l’existence d’un effet de la complexité de la tâche et des effets limités de l’âge et du milieu socio-économique. / When we speak, we move our hands, we make gestures. Gestures help to communicate with others but also to better express our thoughts. Gestures and speech are two dimensions that are part of a unified system of communication based on shared cognitive representations: when a speaker produces a message, most of the information he wants to share is certainly conveyed by speech, but also by gestures (McNeil, 1992). Sometimes this information between gestures and speech is discordant. Goldin-Meadow and Garbert (2002) showed that when participants explain their resolution of the Tower of Hanoi task, the mismatch between the information conveyed by the gesture and the information transmitted orally, may occur either at key moments, indicating the ability to provide two problem-solving strategies, or at uncertain times, showing that participants are torn between several solving strategies. We conducted a study in Colombia among to 144 participants from two contrasting socio-economic backgrounds. The study of the development of planning through the gesture-speech "mismatch" remains understudied despite wide research conducted by Goldin-Meadow. We tried to fill this gap by examining the effects of age, socio-economic background and the complexity of the Tower of Hanoi task upon gesture-speech “mismatches” regarding explanations anticipating the resolution. Our results suggest the existence of an effect of the complexity of the task and limited age and socio-economic background effects.
7

CONCORDANCE-BASED FEEDBACK FOR L2 WRITING IN AN ONLINE ENVIRONMENT

Parise, Peter, 0009-0006-4628-0185 08 1900 (has links)
Data-driven learning is a sub-discipline of corpus linguistics that makes use of the analyses and tools of corpus linguistics in foreign and second language classroom (Johns, 1991; Johns & King, 1991). With this approach, learners become researchers rather than passive recipients of language rules (Johns, 1991). This study was an investigation of the impact of this approach as a form of written corrective feedback for in-service teachers of English participating in an online writing course at a teacher training institute in Japan. Data-driven learning is commonly utilized in conventional, face-to-face classrooms, or computer lab settings in which there is close direction from the instructor on how to interpret the output of a corpus query. The purpose of this study was to investigate how data-driven learning can be implemented in a blended online environment by providing training to develop the participants’ corpus competence (Charles, 2011; Flowerdew, 2010), which is defined as the ability to interpret data obtained from querying a corpus. This competence has been associated with becoming familiar with corpus methods, which include interpreting concordances, and in turn can aid in accurately repairing writing errors. This training, while initially presented in a face-to-face session at the beginning of the course, was sustained with support from resources on the course’s Moodle website and my comments in Microsoft Word documents. In addition, I applied a fine-grained approach to the analysis of the to examine the quality of participants’ interpretation of concordances. The mixed method triangulation convergence design (Creswell & Plano Clark, 2007, 2011) used in this study was based on data from four sources to examine the effectiveness of data-driven learning in an online environment as well as to observe how the participants interpreted concordances. One data set involved an analysis of the participants’ responses in drafts of their own writing to concordance-based feedback. The participants were given a prefabricated concordance, which was a concordance I generated. That concordance was attached to an error in the participants’ document and the participants used the information provided by the concordance to repair their writing error. The resulting data set, which contains the concordance, along with before and after comparisons of the writers’ repairs, shows how the participants’ interpretations of concordances aided the repairs. With the evidence of several trials over the course of four writing assignments, it was possible to see how the participants used the supplied concordance to repair their writing errors and in turn revealed their degree of corpus competence. A second data set obtained from think-aloud protocols from select participants was utilized to reveal how they interpreted the concordance during an error-repair task. This data revealed what kind of thought processes or noticing that occurred in this task. A third piece of evidence was derived from data obtained from the Moodle website via log files and other resources such as online documents and training quizzes. The purpose was to document which resources the participants accessed relating to data-driven learning training to investigate if those resources aided in their development of corpus competence. The fourth piece of evidence was a quiz developed online to compare the participants with a standard set of items. The quiz was used to investigate which participants successfully or unsuccessfully interpreted the concordances. This instrument, which was analyzed with the Rasch model, allowed for further comparison between the participants’ skill of interpreting concordances. These four data sources were triangulated and in the final analysis cross-referenced to examine how data-driven learning can be successfully applied in a blended online learning environment and how the training of corpus competence aided the learners in interpreting the concordances. / Teaching & Learning
8

USING CORPORA IN A LEXICALIZED STYLISTICS APPROACH TO TEACHING ENGLISH-AS-A-FOREIGN-LANGUAGE LITERATURE

Aljuhani, Hind S 01 March 2016 (has links)
As a lingua franca across the globe, English plays a vital role in international communications. Due to rapid economic, political, and educational globalization, the English language has become a powerful means of communication. Therefore, English education is vital to the development of many countries around the world. Since 1932, the need for a lingua franca in Saudi Arabia developed as the country progressed politically, economically, and educationally. Now, English is important to Saudis’ economic, educational, and career development and success. Vocabulary is a major step in learning any language. By deepening students’ lexical knowledge, they will be able to use English accurately to express themselves. However, teaching words in isolation and through memorization is not highly effective; English-as-a-foreign-language (EFL) learners need to interact with the language and its usage in a more profound way. This can be done by integrating corpora and stylistics analysis in an EFL curriculum. The importance of stylistics analysis to literary texts in the EFL classroom lies in the way that EFL learners will be exposed to authentic language. At the same time they will get insight into how English is structured; and by accessing corpora, which provide a wide range of data for the analysis of stylistics, students will be able to compare the lexical and grammatical patterns in authentic texts. Also, it is important to introduce students to the different levels of English (i.e. semantic, lexis, morphology); this will enlarge EFL learners’ knowledge of English vocabulary and various grammatical patterns. This project offers an innovative perspective on how to teach English for EFL university-level students by using corpora in a lexicalized stylistics approach, which will enable EFL learners to acquire vocabulary by reading literary texts. This provides a rich environment of lexical items and a variety of grammatical patterns. This approach offers EFL learners analytical tools that will improve their linguistic skills as they interact with and analyze authentic examples of English and gain insight about its historical, social and cultural background.
9

Exploring the use of parallel corpora in the complilation of specialised bilingual dictionaries of technical terms: a case study of English and isiXhosa

Shoba, Feziwe Martha 07 1900 (has links)
Text in English / Abstracts in English, isiXhosa and Afrikaans / The Constitution of the Republic of South Africa, Act 108 of 1996, mandates the state to take practical and positive measures to elevate the status and the use of indigenous languages. The implementation of this pronouncement resulted in a growing demand for specialised translations in fields like technology, science, commerce, law and finance. The lack of terminology and resources such as specialised bilingual dictionaries in indigenous languages, particularly isiXhosa remains a growing concern that hinders the translation and the intellectualisation of isiXhosa. A growing number of African scholars affirm the importance of specialised dictionaries in the African languages as tools for language and terminology development so that African languages can be used in the areas of science and technology. In the light of the background above, this study explored how parallel corpora can be interrogated using a bilingual concordancer, ParaConc to extract bilingual terminology that can be used to create specialised bilingual dictionaries. A corpus-based approach was selected due to its speed, efficiency and accuracy in extracting bilingual terms in their immediate contexts. In enhancing the research outcomes, Descriptive Translations Studies (DTS) and Corpus-based translation studies (CTS) were used in a complementary manner. Because the study is interdisciplinary, the function theories of lexicography that emphasise the function and needs of users were also applied. The analysis and extraction of bilingual terminology for dictionary making was successful through the use of the following ParaConc features, namely frequencies, hot word lists, hot words, search facility and concordances (Key Word in Context), among others. The findings revealed that English-isiXhosa Parallel Corpus is a repository of translation equivalents and other information categories that can make specialised dictionaries more user-friendly and multifunctional. The frequency lists were revealed as an effective method of selecting headwords for inclusion in a dictionary. The results also unraveled the complex functions of bilingual concordances where information on collocations and multiword units, sense distinction and usage examples could be easily identifiable proving that this approach is more efficient than the traditional method. The study contributes to the knowledge on corpus-based lexicography, standardisation of finance terminology resource development and making of user-friendly dictionaries that are tailor-made for different needs of users. / Umgaqo-siseko weli loMzantsi Afrika ukhululele uRhulumente ukuba athabathe amanyathelo abonakalayo ekuphuhliseni nasekuphuculeni iilwimi zesiNtu. Esi sindululo sibangele ukwanda kokuguqulelwa kwamaxwebhu angezobuchwepheshe, inzululwazi, umthetho, ezemali noqoqosho angesiNgesi eguqulelwa kwiilwimi ebezifudula zingasiwe-so ezinjengesiXhosa. Ukunqongophala kwesigama kunye nezichazi-magama kube yingxaki enkulu ekuguquleleni ngakumbi izichazi-magama ezilwimi-mbini eziqulethe isigama esikhethekileyo. Iingcali ezininzi ziyangqinelana ukuba olu hlobo lwezi zichazi-magama luyimfuneko kuba ludlala iindima enkulu ekuphuhlisweni kweelwimi zesiNtu, ekuyileni isigama, nasekusetyenzisweni kwazo kumabakala obunzululwazi nobuchwepheshe. Olu phando ke luvavanya ukusetyenziswa kwekhophasi equlethe amaxwebhu esiNgesi neenguqulelo zawo zesiXhosa njengovimba wokudimbaza isigama sezemali esinokunceda ekuqulunqweni kwesichazi-magama esilwimi-mbini. Isizathu esibangele ukukhetha le ndlela yophando esebenzisa ikhompyutha kukuba iyakhawuleza, ulwazi oluthathwe kwikhophasi luchanekile, yaye isigama kwikhophasi singqamana ngqo nomxholo wamaxwebhu nto leyo eyenza kube lula ukufumana iintsingiselo nemizekelo ephilayo. Ukutyebisa olu phando indlela yekhophasi iye yaxhaswa zezinye iindlela zophando ezityunjiweyo: ufundo lwenguguqulelo oluchazayo (DTS) kunye neendlela zokuguqulela ezijoliswe kumsebenzi nakuhlobo lwabasebenzisi zinguqulelo ezo. Kanti ke ziqwalaselwe neenkqubo zophando lobhalo-zichazi-magama eziinjongo zokuqulunqa izichazi-magama ezesebenzisekayo neziluncedo kuninzi lwabasebenzisi zichazi-magama ngakumbi kwisizwe esisebenzisa iilwimi ezininzi. Ukuhlalutya nokudimbaza isigama kwikhophasi kolu phando kusetyenziswe isixhobo sekhompyutha esilungiselelwe ikhophasi enelwiimi ezimbini nangaphezulu ebizwa ngokuba yiParaConc. Iziphumo zolu phando zibonise mhlophe ukuba ikhophasi eneenguqulelo nguvimba weendidi ngendidi zamagama nolwazi olunokuphucula izichazi-magama zeli xesha. Kaloku abaguquleli basebenzise amaqhinga ngamaqhinga ukunika iinguqulelo bekhokelwa yimigomo nemithetho yoguqulelo enxuse abasebenzisi bamaxwebhu aguqulelweyo. Ubuchule beParaConc bokukwazi ukuhlela amagama ngokwendlela afumaneka ngayo kunye neenkcukacha zamanani budandalazise indlela eyiyo yokukhetha imichazwa enokungena kwisichazi-magama. Iziphumo zikwabonakalise iintlaninge yolwazi olufumaneka kwiKWIC, lwazi olo olungelula ukulufumana xa usebenzisa undlela-ndala wokwakha isichazi-magama. Esi sifundo esihlanganyele uGuqulelo olusekelwe kwiKhophasi noQulunqo-zichazi-magama zobuchwepheshe luya kuba negalelo elingathethekiyo kwindlela yokwakha izichazi-magama kwilwiimi zeSintu ngokubanzi nancakasana kwisiXhosa, nto leyo eya kothula umthwalo kubaqulunqi-zichazi-magama. Ukwakha nokuqulunqa izichazi-magama ezilwimi-mbini zezemali kuya kwandisa imithombo yesigama esinqongopheleyo kananjalo sivelise izichazi-magama eziluncedo kwisininzi sabantu. / Die Grondwet van die Republiek van Suid-Afrika, Wet 108 van 1996, gee aan die staat die mandaat om praktiese en positiewe maatreëls te tref om die status en gebruik van inheemse tale te verhoog. Die implementering van hierdie uitspraak het gelei tot ’n toenemende vraag na gespesialiseerde vertalings in domeine soos tegnologie, wetenskap, handel, regte en finansies. Die gebrek aan terminologie en hulpbronne soos gespesialiseerde woordeboeke in inheemse tale, veral Xhosa, wek toenemende kommer wat die vertaling en die intellektualisering van Xhosa belemmer. ’n Toenemende aantal vakkundiges in Afrika beklemtoon die belangrikheid van gespesialiseerde woordeboeke in die Afrikatale as instrumente vir taal- en terminologie-ontwikkeling sodat Afrikatale gebruik kan word in die areas van wetenskap en tegnologie. In die lig van die voorafgaande agtergrond het hierdie studie ondersoek ingestel na hoe parallelle korpora deursoek kan word deur ’n tweetalige konkordanser (ParaConc) te gebruik om tweetalige terminologie te ontgin wat gebruik kan word in die onwikkeling van tweetalige gespesialiseerde woordeboeke. ’n Korpusgebaseerde benadering is gekies vir die spoed, doeltreffendheid en akkuraatheid waarmee dit tweetalige terme uit hulle onmiddellike kontekste kan onttrek. Beskrywende Vertaalstudies (DTS) en Korpusgebaseerde Vertaalstudies (CTS) is op ’n aanvullende wyse gebruik om die navorsingsuitkomste te verbeter. Aangesien die studie interdissiplinêr is, is die funksieteorieë van leksikografie wat die funksie en behoeftes van gebruikers beklemtoon, ook toegepas. Die analise en ontginning van tweetalige terminologie om woordeboeke te ontwikkel was suksesvol deur, onder andere, gebruik te maak van die volgende ParaConc-eienskappe, naamlik, frekwensies, hotword-lyste, hot words, die soekfunksie en konkordansies (Sleutelwoord-in-Konteks). Die bevindings toon dat ’n Engels-Xhosa Parallelle Korpus ’n bron van vertaalekwivalente en ander inligtingskategorieë is wat gespesialiseerde woordeboeke meer gebruikersvriendelik en multifunksioneel kan maak. Die frekwensielyste is geïdentifiseer as ’n doeltreffende metode om hoofwoorde te selekteer wat opgeneem kan word in ’n woordeboek. Die bevindings het ook die komplekse funksies van tweetalige konkordansers ontknoop waar inligting oor kollokasies en veelvuldigewoord-eenhede, betekenisonderskeiding en gebruiksvoorbeelde maklik identifiseer kon word wat aandui dat hierdie metode viii doeltreffender is as die tradisionele metode. Die studie dra by tot die kennisveld van korpusgebaseerde leksikografie, standaardisering van finansiële terminologie, hulpbronontwikkeling en die ontwikkeling van gebruikersvriendelike woordeboeke wat doelgemaak is vir verskillende behoeftes van gebruikers. / Linguistics and Modern Languages / D. Litt. et Phil. (Linguistics (Translation Studies))
10

Re-Ranking auf Basis von Bradfordizing für die verteilte Suche in digitalen Bibliotheken

Mayr, Philipp 06 March 2009 (has links)
Trotz großer Dokumentmengen für datenbankübergreifende Literaturrecherchen erwarten akademische Nutzer einen möglichst hohen Anteil an relevanten und qualitativen Dokumenten in den Trefferergebnissen. Insbesondere die Reihenfolge und Struktur der gelisteten Ergebnisse (Ranking) spielt, neben dem direkten Volltextzugriff auf die Dokumente, inzwischen eine entscheidende Rolle beim Design von Suchsystemen. Nutzer erwarten weiterhin flexible Informationssysteme, die es unter anderem zulassen, Einfluss auf das Ranking der Dokumente zu nehmen bzw. alternative Rankingverfahren zu verwenden. In dieser Arbeit werden zwei Mehrwertverfahren für Suchsysteme vorgestellt, die die typischen Probleme bei der Recherche nach wissenschaftlicher Literatur behandeln und damit die Recherchesituation messbar verbessern können. Die beiden Mehrwertdienste semantische Heterogenitätsbehandlung am Beispiel Crosskonkordanzen und Re-Ranking auf Basis von Bradfordizing, die in unterschiedlichen Phasen der Suche zum Einsatz kommen, werden hier ausführlich beschrieben und im empirischen Teil der Arbeit bzgl. der Effektivität für typische fachbezogene Recherchen evaluiert. Vorrangiges Ziel der Promotion ist es, zu untersuchen, ob das hier vorgestellte alternative Re-Rankingverfahren Bradfordizing im Anwendungsbereich bibliographischer Datenbanken zum einen operabel ist und zum anderen voraussichtlich gewinnbringend in Informationssystemen eingesetzt und dem Nutzer angeboten werden kann. Für die Tests wurden Fragestellungen und Daten aus zwei Evaluationsprojekten (CLEF und KoMoHe) verwendet. Die intellektuell bewerteten Dokumente stammen aus insgesamt sieben wissenschaftlichen Fachdatenbanken der Fächer Sozialwissenschaften, Politikwissenschaft, Wirtschaftswissenschaften, Psychologie und Medizin. Die Evaluation der Crosskonkordanzen (insgesamt 82 Fragestellungen) zeigt, dass sich die Retrievalergebnisse signifikant für alle Crosskonkordanzen verbessern; es zeigt sich zudem, dass interdisziplinäre Crosskonkordanzen den stärksten (positiven) Effekt auf die Suchergebnisse haben. Die Evaluation des Re-Ranking nach Bradfordizing (insgesamt 164 Fragestellungen) zeigt, dass die Dokumente der Kernzone (Kernzeitschriften) für die meisten Testreihen eine signifikant höhere Precision als Dokumente der Zone 2 und Zone 3 (Peripheriezeitschriften) ergeben. Sowohl für Zeitschriften als auch für Monographien kann dieser Relevanzvorteil nach Bradfordizing auf einer sehr breiten Basis von Themen und Fragestellungen an zwei unabhängigen Dokumentkorpora empirisch nachgewiesen werden. / In spite of huge document sets for cross-database literature searches, academic users expect a high ratio of relevant and qualitative documents in result sets. It is particularly the order and structure of the listed results (ranking) that play an important role when designing search systems alongside the direct full text access for documents. Users also expect flexible information systems which allow influencing the ranking of documents and application of alternative ranking techniques. This thesis proposes two value-added approaches for search systems which treat typical problems in searching scientific literature and seek to improve the retrieval situation on a measurable level. The two value-added services, semantic treatment of heterogeneity (the example of cross-concordances) and re-ranking on Bradfordizing, which are applied in different search phases, are described in detail and their effectiveness in typical subject-specific searches is evaluated in the empirical part of the thesis. The preeminent goal of the thesis is to study if the proposed, alternative re-ranking approach Bradfordizing is operable in the domain of bibliographic databases, and if the approach is profitable, i.e. serves as a value added, for users in information systems. We used topics and data from two evaluation projects (CLEF and KoMoHe) for the tests. The intellectually assessed documents come from seven academic abstracting and indexing databases representing social science, political science, economics, psychology and medicine. The evaluation of the cross-concordances (82 topics altogether) shows that the retrieval results improve significantly for all cross-concordances, indicating that interdisciplinary cross-concordances have the strongest (positive) effect on the search results. The evaluation of Bradfordizing re-ranking (164 topics altogether) shows that core zone (core journals) documents display significantly higher precision than was seen for documents in zone 2 and zone 3 (periphery journals) for most test series. This post-Bradfordizing relevance advantage can be demonstrated empirically across a very broad basis of topics and two independent document corpora as well for journals and monographs.

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