1,720,987 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Digital Watermarking for Verification of Perception-based Integrity of Audio Data
No full textIn certain application fields digital audio recordings contain sensitive content. Examples are historical archival material in public archives that preserve our cultural heritage, or digital evidence in the context of law enforcement and civil proceedings. Because of the powerful capabilities of modern editing tools for multimedia such material is vulnerable to doctoring of the content and forgery of its origin with malicious intent. Also inadvertent data modification and mistaken origin can be caused by human error. Hence, the credibility and provenience in terms of an unadulterated and genuine state of such audio content and the confidence about its origin are critical factors.
To address this issue, this PhD thesis proposes a mechanism for verifying the integrity and authenticity of digital sound recordings. It is designed and implemented to be insensitive to common post-processing operations of the audio data that influence the subjective acoustic perception only marginally (if at all). Examples of such operations include lossy compression that maintains a high sound quality of the audio media, or lossless format conversions. It is the objective to avoid de facto false alarms that would be expectedly observable in standard crypto-based authentication protocols in the presence of these legitimate post-processing. For achieving this, a feasible combination of the techniques of digital watermarking and audio-specific hashing is investigated.
At first, a suitable secret-key dependent audio hashing algorithm is developed. It incorporates and enhances so-called audio fingerprinting technology from the state of the art in contentbased audio identification. The presented algorithm (denoted as ”rMAC” message authentication code) allows ”perception-based” verification of integrity. This means classifying integrity breaches as such not before they become audible. As another objective, this rMAC is embedded and stored silently inside the audio media by means of audio watermarking technology. This approach allows maintaining the authentication code across the above-mentioned admissible post-processing operations and making it available for integrity verification at a later date. For this, an existent secret-key ependent audio watermarking algorithm is used and enhanced in this thesis work.
To some extent, the dependency of the rMAC and of the watermarking processing from a secret key also allows authenticating the origin of a protected audio. To elaborate on this security aspect, this work also estimates the brute-force efforts of an adversary attacking this combined rMAC-watermarking approach. The experimental results show that the proposed method provides a good distinction and classification
performance of authentic versus doctored audio content. It also allows the temporal localization of audible data modification within a protected audio file. The experimental evaluation finally provides recommendations about technical configuration settings of the combined watermarking-hashing approach.
Beyond the main topic of perception-based data integrity and data authenticity for audio, this PhD work provides new general findings in the fields of audio fingerprinting and digital watermarking. The main contributions of this PhD were published and presented mainly at conferences about multimedia security. These publications were cited by a number of other authors and hence had some impact on their works
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Digitale Wasserzeichen zur Verifikation der wahrnehmungsbasierten Integrität von Audiodaten
No full textIn certain application fields digital audio recordings contain sensitive content. Examples are historical archival material in public archives that preserve our cultural heritage, or digital evidence in the context of law enforcement and civil proceedings. Because of the powerful capabilities of modern editing tools for multimedia such material is vulnerable to doctoring of the content and forgery of its origin with malicious intent. Also inadvertent data modification and mistaken origin can be caused by human error. Hence, the credibility and provenience in terms of an unadulterated and genuine state of such audio content and the confidence about its origin are critical factors. To address this issue, this PhD thesis proposes a mechanism for verifying the integrity and authenticity of digital sound recordings. It is designed and implemented to be insensitive to common post-processing operations of the audio data that influence the subjective acoustic perception only marginally (if at all). Examples of such operations include lossy compression that maintains a high sound quality of the audio media, or lossless format conversions. It is the objective to avoid de facto false alarms that would be expectedly observable in standard crypto-based authentication protocols in the presence of these legitimate post-processing. For achieving this, a feasible combination of the techniques of digital watermarking and audio-specific hashing is investigated. At first, a suitable secret-key dependent audio hashing algorithm is developed. It incorporates and enhances so-called audio fingerprinting technology from the state of the art in contentbased audio identification. The presented algorithm (denoted as ""rMAC"" message authentication code) allows ""perception-based"" verification of integrity. This means classifying integrity breaches as such not before they become audible. As another objective, this rMAC is embedded and stored silently inside the audio media by means of audio watermarking technology. This approach allows maintaining the authentication code across the above-mentioned admissible post-processing operations and making it available for integrity verification at a later date. For this, an existent secret-key ependent audio watermarking algorithm is used and enhanced in this thesis work. To some extent, the dependency of the rMAC and of the watermarking processing from a secret key also allows authenticating the origin of a protected audio. To elaborate on this security aspect, this work also estimates the brute-force efforts of an adversary attacking this combined rMAC-watermarking approach. The experimental results show that the proposed method provides a good distinction and classification performance of authentic versus doctored audio content. It also allows the temporal localization of audible data modification within a protected audio file. The experimental evaluation finally provides recommendations about technical configuration settings of the combined watermarking-hashing approach. Beyond the main topic of perception-based data integrity and data authenticity for audio, this PhD work provides new general findings in the fields of audio fingerprinting and digital watermarking. The main contributions of this PhD were published and presented mainly at conferences about multimedia security. These publications were cited by a number of other authors and hence had some impact on their works.In bestimmten Anwendungsfeldern enthalten digitale Tonaufzeichnungen zuweilen sensible Inhalte. Beispiele hierfür sind historisches Archivmaterial, das in öffentlichen Archiven unser kulturelles Erbe bewahrt; oder Tonaufzeichnungen als Indizien im Kontext von Strafverfolgung und Zivilstreitigkeiten. Angesichts der Leistungsfähigkeit moderner Bearbeitungstools für Multimedia ist dieses Material anfällig gegenüber Manipulationen des Inhaltes und Fälschung des Ursprungs in böwilliger Absicht. Unbeabsichtigte Veränderungen aufgrund von technischem oder menschlichem Versagen können in der Praxis ebenfalls vorkommen. Die Vertrauenswürdigkeit dieses Materials im Sinne von Unverfälschtheit des Inhaltes und Echtheit der ursprünglichen Quelle sind daher kritische Faktoren. Für die Behandlung dieses Problems stellt diese Dissertation daher ein Verfahren zur Verifikation der Integrität und der Authentizität digitaler Tonaufzeichnungen vor. Es ist unempfindlich gegenüber gängigen Bearbeitungsschritten im Lebenszyklus der Audiodaten, die die subjektive Klangwahrnehmung nur unwesentlich oder gar nicht beeinflussen. Beispiele hierzu sind verlustbehaftete Kompression bei hoher Klangqualität oder verlustfreie Formatwandlung. Es ist das Ziel, de facto falsch-positive Detektionen in der Gegenwart dieser - legitimen - Bearbeitungsschritte zu vermeiden, wie sie bei Standardverfahren für kryptografiebasierte Echtheitsprüfungen zu erwarten wären. Um dieses Ziel zu erreichen, wird eine geeignete Kombination der Technologien der ""Digitalen Wasserzeichen"" mit audio-spezifischen Hashfunktionen untersucht. Hierzu wird im ersten Schritt ein geeignetes schlüsselabhängiges Audio-Hashverfahren entwickelt. Es nutzt und erweitert Erkenntnisse des sog. ""Audio-Fingerprintings"" aus dem Bereich der inhaltsbasierten Audio-Identifizierungsverfahren. Der vorgestellte Algorithmus (im Folgenden bezeichnet als ""rMAC""-Authentifizierungscode) erlaubt die sog. ""wahrnehmungs-basierte"" Verifikation der Integrität. Dies bedeutet, Integritätsverletzungen als solche zu klassifizieren (erst) sobald sie hörbar werden. Als weiteres Ziel werden diese Authentifizierungscodes mittels Audio-Wasserzeichen-Technologie unhörbar innerhalb der Audiodaten eingebettet und gespeichert. Dies erlaubt die Authentifizierungscodes auch über die oben erwähnten, zulässigen Bearbeitungsschritte hinweg mitzuführen und für eine spätere Integritätsprüfung verfügbar zu halten. In dieser Arbeit wird dazu ein existierendes Audiowasserzeichen-Verfahren gezielt weiterentwickelt. Die Schlüsselabhängigkeit der rMAC- und Wasserzeichen-Algorithmen erlaubt es auch, in eingeschränktem Maße, die Authentizität der geschützten Audiodaten zu prüfen. Hierzu analysiert diese Dissertation auch den Aufwand für Bruteforce-Angriffe auf das vorgestellte, schlüsselabhängige Verfahren der Echtheitsprüfung. Die experimentellen Ergebnisse zeigen, dass das entwickelte Verfahren eine gute Trennschärfe bei der Klassifizierung zwischen echten und gefälschten Audioinhalten bietet. Es erlaubt weiterhin eine zeitliche Lokalisierung der Datenveränderungen innerhalb einer Datei. Die experimentelle Evaluation liefert schließlich auch Empfehlungen über geeignete technische Feineinstellungen des Verfahrens. Über die Frage der wahrnehmungsbasierten Echtheitsprüfung für Audio hinaus, liefert diese Dissertation auch neue allgemeine Erkenntnisse in den Bereichen des Audio Fingerprintings und der digitalen Wasserzeichen für sich. Die Hauptbeiträge dieser Arbeit wurden auf Fachkonferenzen der Multimedia-Sicherheit vorgestellt. Diese Publikationen wurden anschließend von einer Reihe anderer Autoren zitiert und haben daher weiterführende Arbeiten zum Thema mitbeeinflusst
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Content-based Message Authentication Coding for Audio Data
No full textCurrent systems and protocols based on cryptographic methods for integrity and authenticity verification of media data do not distinguish between legitimate signal transformation and malicious tampering that manipulates the content. Furthermore, they usually provide no localization or assessment of the relevance of such manipu- lations with respect to human perception or semantics. For the verification of digital audio data we present an algorithm for a robust message authentication code in the context of content fragile authentication watermarking. Therefore we introduce an extension of an existing audio fingerprinting approach with respect to security and synchronization with audio watermarking. The experimental results show that the pro- posed algorithm provides both a high level of distinction between perceptually different audio data and a high robustness against signal transformations that do not change the perceived information
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