Aktuelle Softwaresysteme erlauben die verteilte Authentifizierung von Benutzern über Ver-zeichnisdienste, die sowohl im Intranet als auch im Extranet liegen und die über Domänen-grenzen hinweg die Kooperation mit Partnern ermöglichen. Der nächste Schritt ist es nun, die Autorisierung ebenfalls aus der lokalen Anwendung auszulagern und diese extern durchzu-führen – vorzugsweise unter dem Einfluss der Authentifizierungspartner. Basierend auf der Analyse des State-of-the-Art wird in dieser Arbeit ein Framework vorges-tellt, das die verteilte Autorisierung von ADFS (Active Directory Federation Services) authenti-fizierten Benutzern auf Basis ihrer Gruppen oder ihrer persönlichen Identität ermöglicht. Es wird eine prototypische Implementation mit Diensten entwickelt, die für authentifizierte Be-nutzer Autorisierungsanfragen extern delegieren, sowie ein Dienst, der diese Autorisierungs-anfragen verarbeitet. Zusätzlich zeigt die Arbeit eine Integration dieses Autorisierungs-Frameworks in das .NET Framework, um die praxistaugliche Verwendbarkeit in einer aktuel-len Entwicklungsumgebung zu demonstrieren. Abschließend wird ein Ausblick auf weitere Fragestellungen und Folgearbeiten gegeben. / Current software systems allow distributed authentication of users using directory services, which are located both in the intranet and in the extranet, to establish cooperation with part-ners over domain boundaries. The next step is to outsource the authorization out of the local applications and to delegate the authorization decisions to external parties. In particular the authorization request is back delegated to the authentication partner. Based on an analysis of the state of the art this paper presents a framework which allows the distributed authorisation of ADFS authenticated users. The authorization decisions are based on the user’s identity and groups. In this work there will be developed a prototypical imple-mentation of services which are capable of delegating authorization requests. Additionally, this work points out the integration of these services into the .NET framework to demonstrate the usability in a modern development environment. Finally there will be a prospect of further questions and work.

This dissertation presents segmental discriminative analysis techniques for American Sign Language (ASL) recognition and verification. ASL recognition is a sequence classification problem. One of the most successful techniques for recognizing ASL is the hidden Markov model (HMM) and its variants. This dissertation addresses two problems in sign recognition by HMMs. The first is discriminative feature selection for temporally-correlated data. Temporal correlation in sequences often causes difficulties in feature selection. To mitigate this problem, this dissertation proposes segmentally-boosted HMMs (SBHMMs), which construct the state-optimized features in a segmental and discriminative manner. The second problem is the decomposition of ASL signs for efficient and accurate recognition. For this problem, this dissertation proposes discriminative state-space clustering (DISC), a data-driven method of automatically extracting sub-sign units by state-tying from the results of feature selection. DISC and SBHMMs can jointly search for discriminative feature sets and representation units of ASL recognition. ASL verification, which determines whether an input signing sequence matches a pre-defined phrase, shares similarities with ASL recognition, but it has more prior knowledge and a higher expectation of accuracy. Therefore, ASL verification requires additional discriminative analysis not only in utilizing prior knowledge but also in actively selecting a set of phrases that have a high expectation of verification accuracy in the service of improving the experience of users. This dissertation describes ASL verification using CopyCat, an ASL game that helps deaf children acquire language abilities at an early age. It then presents the "probe" technique which automatically searches for an optimal threshold for verification using prior knowledge and BIG, a bi-gram error-ranking predictor which efficiently selects/creates phrases that, based on the previous performance of existing verification systems, should have high verification accuracy. This work demonstrates the utility of the described technologies in a series of experiments. SBHMMs are validated in ASL phrase recognition as well as various other applications such as lip reading and speech recognition. DISC-SBHMMs consistently produce fewer errors than traditional HMMs and SBHMMs in recognizing ASL phrases using an instrumented glove. Probe achieves verification efficacy comparable to the optimum obtained from manually exhaustive search. Finally, when verifying phrases in CopyCat, BIG predicts which CopyCat phrases, even unseen in training, will have the best verification accuracy with results comparable to much more computationally intensive methods.

A sign pattern(matrix) is a matrix whose entries are from the set {+,-,0}. An n x n sign pattern matrix is a spectrally arbitrary pattern(SAP) if for every monic real polynomial p(x) of degree n, there exists a real matrix B whose entries agree in sign with A such that the characteristic polynomial of B is p(x). An n x n pattern A is an inertialy arbitrary pattern(IAP) if (r,s,t) belongs to the inertia set of A for every nonnegative triple (r,s,t) with r+s+t=n. Some elementary results on these two classes of patterns are first exhibited. Tree sign patterns are then investigated, with a special emphasis on 4 x 4 tridiagonal sign patterns. Connections between the SAP(IAP) classes and the classes of potentially nilpotent and potentially stable patterns are explored. Some interesting open questions are also provided.

No description available.

No description available.

Traffic signs are ubiquitous in the road environment, and are a crucial and cost-effective means of ensuring traffic safety. In Queensland, Australia, a class of temporary traffic signs is used for roadwork applications, and has recently been expanded to include Multiple-Message Signs: a novel, and as yet empirically untested system, which presents numerous advantages in terms of flexibility and economy. However, potential Human Factors problems surround aspects of the design of multiple message signs. In particular, the efficiency with which information is communication may be compromised relative to single message signs. The project involved a series of laboratory studies focussing on the behavioural requirements of temporary roadworks signs, beginning with the improvement of response characteristics of a sign used to communicate lane-closure. In the first empirical study, a proposed redesign of the Lane-Status sign based on principles of warning communication was found to be more effective than the original sign. The same sign was then examined in the context of multiple-message presentation, and significant cost s with respect to the speed and accuracy of responses relative to single-message presentation were found. A subsequent study investigated multiple-message presentation of speed limit information, which is more familiar and widely encountered than lane-closure information. Similar costs for multiple-message presentation were found. However, there were data to suggest that the additional information in multiple-message signs, if used correctly, may offer drivers and additional incentive to reduce speed. The next two studies were concerned with the effects of presentation, content type (e.g., speed-limit, symbolic and text-based) and visual clutter on recognition and visual search for traffic signs. The presentation of information via multiple message signs was compared with spatially distributed single message signs, with information matched with respect to message length and sign content. Overall advantages for multiple message presentation were found for recognition, which were particularly robust for speed limit information. The results for visual search indicated some benefits to multiple message presentation, but were less decisive than those for recognition. The final two studies investigated the possibility of improving response characteristics of single-message signs with sequential, rather then individual presentation. The role of the temporal interval between successive sign presentations was explored, which has implications for the feasibility of sequential presentation in practice. In addition, the nature of sign pairs presented in sequence – identical, or of the same meaning – was found to be important. Generally, benefits to sequential presentation diminished with increases in the temporal separation interval. In terms of practical implications, the viability of introducing the proposed design changes to the Lane Status sign is discussed. The results pertaining to multiple-message sign are evaluated in the context of published design guidelines, and theoretical and practical issues surrounding sequential sign presentation are reviewed. Finally, possibilities for future research, in part based on the limitations of the current work, are expounded.

Traffic signs are ubiquitous in the road environment, and are a crucial and cost-effective means of ensuring traffic safety. In Queensland, Australia, a class of temporary traffic signs is used for roadwork applications, and has recently been expanded to include Multiple-Message Signs: a novel, and as yet empirically untested system, which presents numerous advantages in terms of flexibility and economy. However, potential Human Factors problems surround aspects of the design of multiple message signs. In particular, the efficiency with which information is communication may be compromised relative to single message signs. The project involved a series of laboratory studies focussing on the behavioural requirements of temporary roadworks signs, beginning with the improvement of response characteristics of a sign used to communicate lane-closure. In the first empirical study, a proposed redesign of the Lane-Status sign based on principles of warning communication was found to be more effective than the original sign. The same sign was then examined in the context of multiple-message presentation, and significant cost s with respect to the speed and accuracy of responses relative to single-message presentation were found. A subsequent study investigated multiple-message presentation of speed limit information, which is more familiar and widely encountered than lane-closure information. Similar costs for multiple-message presentation were found. However, there were data to suggest that the additional information in multiple-message signs, if used correctly, may offer drivers and additional incentive to reduce speed. The next two studies were concerned with the effects of presentation, content type (e.g., speed-limit, symbolic and text-based) and visual clutter on recognition and visual search for traffic signs. The presentation of information via multiple message signs was compared with spatially distributed single message signs, with information matched with respect to message length and sign content. Overall advantages for multiple message presentation were found for recognition, which were particularly robust for speed limit information. The results for visual search indicated some benefits to multiple message presentation, but were less decisive than those for recognition. The final two studies investigated the possibility of improving response characteristics of single-message signs with sequential, rather then individual presentation. The role of the temporal interval between successive sign presentations was explored, which has implications for the feasibility of sequential presentation in practice. In addition, the nature of sign pairs presented in sequence – identical, or of the same meaning – was found to be important. Generally, benefits to sequential presentation diminished with increases in the temporal separation interval. In terms of practical implications, the viability of introducing the proposed design changes to the Lane Status sign is discussed. The results pertaining to multiple-message sign are evaluated in the context of published design guidelines, and theoretical and practical issues surrounding sequential sign presentation are reviewed. Finally, possibilities for future research, in part based on the limitations of the current work, are expounded.

Thesis (MSc (Computer Science))--University of Stellenbosch, 2005. / Sign Languages such as South African Sign Language, are proper natural languages; they have their own vocabularies, and they make use of their own grammar rules. However, machine translation from a spoken to a signed language creates interesting challenges. These problems are caused as a result of the differences in character between spoken and signed languages. Sign Languages are classified as visual-spatial languages: a signer makes use of the space around him, and gives visual clues from body language, facial expressions and sign movements to help him communicate. It is the absence of these elements in the written form of a spoken language that causes the contextual ambiguities during machine translation. The work described in this thesis is aimed at resolving the ambiguities caused by a translation from written English to South African Sign Language. We designed and implemented a preprocessor that uses areas of linguistics such as anaphora resolution and a data structure called a scene graph to help with the spatial aspect of the translation. The preprocessor also makes use of semantic and syntactic analysis, together with the help of a semantic relational database, to find emotional context from text. This analysis is then used to suggest body language, facial expressions and sign movement attributes, helping us to address the visual aspect of the translation. The results show that the system is flexible enough to be used with different types of text, and will overall improve the quality of a machine translation from English into a Sign Language.

Les composantes innée et acquise de l'immunité travaillent ensemble pour assurer une protection efficace de l'organisme. Les cellules dendritiques, cellules sentinelles de l’immunité capturent via des récepteurs de surface les agents pathogènes et les présentent aux lymphocytes T pour stimuler les réponses immunitaires adaptatives spécifiques. Une famille de ces récepteurs, nommée Récepteurs Lectines de type C (CLRs) ont un rôle important dans la reconnaissance de motifs oligosaccharides des pathogènes. Leurs fonctions sont parfois détournées par certains pathogènes à leur avantage et notamment le VIH. La reconnaissance du virus par DC-SIGN, une des CLRs, favorise la dissémination du virus. A l’inverse, la langerine, autre CLR, est considérée comme une barrière naturelle au VIH. Ainsi, DC-SIGN est devenue une cible thérapeutique prometteuse mais sa reconnaissance des ligands osidiques est largement partagée par la langerine.Ce travail vise à développer des antagonistes de DC-SIGN spécifiques et de hautes affinités permettant de rivaliser avec la présentation multivalente des glycosylations de gp120 du VIH avec DC-SIGN. Une approche rationnelle a été employée dans le développement de ligands glycomimétiques hautement sélectifs pour DC-SIGN à partir de l’étude du site de liaison des deux CLRs. Puis, des plates-formes de présentations de ces glycomimétiques, de valences et de géométries différentes, sont comparées par SPR. Les améliorations spectaculaires d'affinités parfois observées sont liées à différents mécanismes d’interactions multivalentes responsables d’un phénomène d’avidité.Sur une des architecture de présentation sélectionnée (RODs), un travail de caractérisation fine des mécanismes responsables de ce gain d’affinité et/ou d’avidité a été conduit par la combinaison de plusieurs techniques biophysiques (SPR, ITC, polarisation de fluorescence et AUC). L’influence de la topologie de cette structure sur les mécanismes d’interactions est ainsi mise en évidence. Par les travaux menés, plusieurs ligands multivalents ont montré des affinités sans précédent pour DC SIGN atteignant des affinités du nanomolaire et représentant les meilleurs inhibiteurs connus à ce jour.Associé au développement d’antagonistes multivalents, une CLR (DCIR) a été identifiée récemment comme impliquée dans la dissémination du VIH, comme DC¬SIGN. Dans une perspective future de développement de glycomimétique, des travaux ont été menés sur la caractérisation structurale et fonctionnelle de ce nouvel acteur dans la problématique VIH. / The innate and acquired immunity components work together to provide efficient protection of organisms. Dendritic cells, sentinel cells of the immunity, are able to capture pathogens through their receptors on the surface and they can present the antigens to lymphocytes T in order to stimulate specific adaptive immune responses. Among these receptors, there is a family named C-type lectin receptors (CLRs), which has an important role in the recognition of pathogenic oligosaccharide motifs. CLRs can be hijacked by many pathogens including HIV. DC-SIGN, one of the CLRs, interacts with the virus and promotes its dissemination. Unlike DC-SIGN, langerin, another CLR, has a protective role against the HIV infection. In this context, DC-SIGN became a promising therapeutic target but it shares ligand specificities with langerin.This work aims to develop highly specific antagonists against DC-SIGN in order to compete with the multivalent glycosylated gp120 protein of HIV. Using the study of the two lectins binding sites as starting point, a rational approach has been exploited to develop highly selective glycomimetics against DC SIGN. The SPR technique was used to investigate multivalent platforms with different valencies as well as ligand presentation in space. The amazing improvement of the affinity observed in some cases can be linked to different mechanisms of multivalent interactions, leading to an avidity phenomenon. On a selected scaffold (RODs), we characterized the different mechanisms responsible for the affinity and/or avidity gains, using a combination of different biophysical techniques (SPR, ITC, fluorescence polarization, AUC). In this work, we highlighted that the topology of this structure can influence the mechanisms of interactions. Overall, different multivalent ligands showed unique affinities for DC-SIGN, reaching the nanomolar affinity range, and they represent the best inhibitors to date.Finally, another CLR has been recently identified as one of the protein involved in the HIV infection as well as DC-SIGN. In a future perspective of glycomimetic development, structural and functional characterization has been done on this new actor involved in the HIV issue.

>Magister Scientiae - MSc / Many South African Deaf people use their mobile phones for communication with SMSs yet they would prefer to converse in South African Sign Language. Deaf people with a capital `D' are different from deaf or hard of hearing as they primarily use sign language to communicate. This study explores how to design and evaluate a prototype that will allow a Deaf person using SASL to tell a hearing doctor how s/he is feeling and provide a way for the doctor to respond. A computer{based prototype was designed and evaluated with the Deaf people in a previous study. Results from the user trial of the computer{based mock{up indicated that Deaf users would like to see the prototype on a cell phone. Those user trial results, combined with our own user survey results conducted with Deaf people, are used as requirements. We built a prototype for a mobile phone browser by embedding SASL videos inside XHTML pages using Adobe Flash. The prototype asks medical questions using SASL videos. These questions are arranged in an organized way that helps in identifying a medical problem. The answers to the questions are then displayed in English and shown to the doctor on the phone. A content authoring tool was also designed and implemented. The content authoring tool is used for populating the prototype in a context free manner allowing for plug and play scenarios such as a doctor's office, Department of Home A airs or police station. A focus group consisting of Deaf people was conducted to help in the design and pilot trial of the system. A final user trial was conducted with more than thirty Deaf people and the results are presented and analyzed. Data is collected with questionnaires, semi-structured interviews and video recordings. The results indicate that most of the Deaf people found the system easy to learn, easy to navigate through, did not get lost and understood the sign language in the videos on the mobile phone. The hand gestures and facial expressions on the sign language videos were clear. Most of them indicated they would like to use the system for free, and that the system did not ask too many questions. Most of them were happy with the quality of the sign language videos on the mobile phone and would consider using the system in real life. Finally they felt their private information was safe while using the system. Many South African Deaf people use their mobile phones for communication with SMSs yet they would prefer to converse in South African Sign Language. Deaf people with a capital `D' are different from deaf or hard of hearing as they primarily use sign language to communicate. This study explores how to design and evaluate a prototype that will allow a Deaf person using SASL to tell a hearing doctor how s/he is feeling and provide a way for the doctor to respond. A computer{based prototype was designed and evaluated with the Deaf people in a previous study. Results from the user trial of the computer{based mock{up indicated that Deaf users would like to see the prototype on a cell phone. Those user trial results, combined with our own user survey results conducted with Deaf people, are used as requirements. We built a prototype for a mobile phone browser by embedding SASL videos inside XHTML pages using Adobe Flash. The prototype asks medical questions using SASL videos. These questions are arranged in an organized way that helps in identifying a medical problem. The answers to the questions are then displayed in English and shown to the doctor on the phone. A content authoring tool was also designed and implemented. The content authoring tool is used for populating the prototype in a context free manner allowing for plug and play scenarios such as a doctor's office, Department of Home A airs or police station. A focus group consisting of Deaf people was conducted to help in the design and pilot trial of the system. A final user trial was conducted with more than thirty Deaf people and the results are presented and analyzed. Data is collected with questionnaires, semi-structured interviews and video recordings. The results indicate that most of the Deaf people found the system easy to learn, easy to navigate through, did not get lost and understood the sign language in the videos on the mobile phone. The hand gestures and facial expressions on the sign language videos were clear. Most of them indicated they would like to use the system for free, and that the system did not ask too many questions. Most of them were happy with the quality of the sign language videos on the mobile phone and would consider using the system in real life. Finally they felt their private information was safe while using the system. / South Africa