Dans les systèmes Store and Forward (S&F), le routage comme moyen d'optimisation a été largement étudie mais aucune règle générale n'a pu être établie. Des paramètres et des méthodes d'évaluation spécifiques à ces systèmes n'ont pas encore été définis. Jusqu'à présent seuls des critères appartenant aux réseaux traditionnels étaient utilises (temps, longueur de la route). Or la tolérance aux délais du réseau s&f minimise l'importance de ces critères. De ce fait, pour ces systèmes, il est nécessaire d'employer des mécanismes et des critères mieux adaptent à leurs caractéristiques. Cette étude a pour but de montrer que le routage dans les systèmes s&f peut être aborde a partir de perspectives nouvelles. Pour ce faire, nous utilisons une politique de routage pré calcule depuis la source. Nous présentons un état de l'art sur les systèmes s&f, leurs mécanismes et leurs scénarios d'application. Nous proposons un outil de calcul de routes pour un scenario de communications par satellite compose par deux constellations. Cet instrument est conçu à partir des techniques utilisées dans les systèmes de transport. Nous proposons ensuite un ensemble de nouvelles métriques pour le routage dans les systèmes s&f. Ces métriques permettent de caractériser le système s&f à partir de leur nature propre et d'établir des politiques de routage mieux adaptées à leurs conditions de fonctionnement. Enfin nous présentons les développements possibles dans cette thématique

Since the 1800's, technological advances have extended the foundation on which telemedicine could build. With its evolution, telemedicine has proven to be a means of offering effective health care interventions, from a multitude of disciplines. Teledermatology, a specialty application of telemedicine, offers great potential in improving the standard of dermatologic care by bridging the gap between the expert opinion of dermatologists and those without access to basic dermatologic care, particularly in developing nations, where skin disease continues to be a major public health problem. In Honduras, the setting for this study, and other developing nations, technology to support telemedicine is available. Dermatologic disease is among the most common disease presentations in the developing world, which left untreated due to a lack of access to adequate medical care, can progress causing increased morbidity or even death. A potential but untested solution is teledermatology. Teledermatology offers great potential in improving the standard of dermatologic care by bridging the gap between the expert opinion of dermatologists and those without access to basic dermatologic care. The purpose of this study was to evaluate the prevalence and types of dermatologic conditions and the feasibility of a store-and-forward teledermatology system in an underserved area of Honduras, so as to potentially provide more timely diagnosis and treatment, implementation of preventative measures, and offer long term solutions.so as The justification and significance of this study was the potential of store-and-forward teledermatology to improve the standard of dermatologic care by improving access of populations in underserved areas to dermatology specialists through affordable technology. The methodology of this study was primarily case study descriptive. This study was conducted at a public primary care clinic (JMA Clinic) and satellite sites in underserved areas of Francisco Morazán, Honduras. During a four week period in Spring 2011, patients with dermatologic conditions were examined and photos taken of condition. The patient information was sent to 3 U.S. board certified dermatologists, who provided diagnosis and treatment within 24 hours, which allowed the clinic physician sufficient time to review recommendations before patient follow-up. Patients would receive follow-up within 48 hours of initial visit. Diagnostic agreement, image quality, and user satisfaction were evaluated. IRB forms were submitted and clearance given. The data was analyzed with SPSS using descriptive statistics. The primary findings were the types of dermatologic conditions, interobserver agreement, image quality, and patient and physician satisfaction. The findings of this study substantiate the need for dermatologic care, as approximately 1 out of every 5 patients of the JMA Clinic presented with a dermatologic condition. The majority of these patients were children or women in their late 20s and early 30s; many of whom had their condition for more than a year and most had not received prior therapy. The types of dermatologic conditions observed were typical of that seen at a dermatology clinic in the U.S., yet inclusive of tropical and regional differences. Dermatitis, infectious and pigmentary conditions were the most common presentations. The interobserver diagnostic agreement achieved was 78%, and improved when considering differential diagnoses. Image quality received high ratings. Patients and physicians recorded a high level of overall satisfaction. Physicians indicated improved knowledge of teledermatology. Because of the unique environment and circumstances, the results are limited to the setting in which the study occurs. This project was a pilot study limited to 4 weeks of data collection and will be limited in significance by its duration and small sample size with respect to the conclusions that can be drawn about the prevalence and types of dermatologic conditions. This study illustrates that teledermatology is a viable means of providing dermatologic care to those in an underserved area of Honduras, where a lack of or limited access to general healthcare or specialty dermatologic care exists. The data offers insights to draw conclusions and recommendations on the potential for similar models to be implemented in underserved areas throughout Honduras and other similar regions. / Ph. D.

Teleradiology has far-reaching implications for the health of remote and underserved populations. With coordination of radiographic evaluation and diagnosis from a distance, teleradiology has the potential to raise the standard of patient care throughout the world. Perhaps the safest and most cost-effective mode of teleradiology today is telesonography. The current research determined that telesonography improves the standard of care at a rural, government-run primary clinic within the Dominican Republic. The work reported herein is intended to compare the use of telesonography to the current standard of sonographic examination which is referral to government hospital 60km from the clinic. the following research questions were addressed: When compared to the standard of care, (1) To what extent does the use of asynchronous telesonography increase the percentage of received sonographic reports based on the total number of ultrasound referrals (sonographic reports / total number of referrals)? (2) To what extent does the use of asynchronous telesonography increase the rate of successful follow-up visits based on the total number of ultrasound referrals? (3) To what extent does the elapsed time between ultrasound referral and sonographic report delivery decrease with the use of asynchronous telesonography? (4) To what extent does the elapsed time between ultrasound referral and patient follow-up decrease with the use of asynchronous telesonography? Research methodology included randomly assigning 100 patients with clinical indications for sonographic examination into experimental and control groups during a 9-week implementation period. Findings from this study indicate that the implemented telesonography system, along with patient awareness of such a system, while not having an appreciable effect on the time to patient follow-up, provided a 4-fold increase in the proportion of patient follow-ups and a 6-fold increase in the proportion of returned radiological reports, and delivered those reports to the referring physician 6-times faster than in the control group. This study demonstrates the feasibility of utilizing a store-and forward telesonography system within this setting. Additional research focusing on the impact of telesonography on patient outcomes within this setting is recommended. / Ph. D.

Le but de cette these est d'etudier les schemas de communications les plus utilises, et plus particulierement la diffusion, pour en proposer des implementations efficaces sur des machines paralleles. Dans une premiere partie nous presentons les principales machines paralleles et les differents modes de communication mis en oeuvre dans ces machines. Cette partie illustre le probleme du choix du reseau d'interconnexion pour assembler les processeurs des ordinateurs massivement paralleles. La deuxieme partie est consacree a l'etude des schemas de communications globales dans les grilles toriques en mode store and forward. Dans un premier temps, on presente une nouvelle famille d'arbres de recouvrement disjoints de profondeur minimale, permettant de realiser la diffusion pipeline en temps optimal. Dans un deuxieme temps, on presente l'utilisation d'autres outils tels que les chemins hamiltoniens pour realiser l'echange total. Sur ce dernier type de communication, une etude en mode wormhole est presentee. L'algorithme est inspire du decoupage recursif de la grille torique. Il permet d'obtenir un nombre d'etapes plus faible qu'avec les algorithmes traditionnels en store and forward. Des resultats experimentaux sur machine MegaNode a 128 Transputers, permettent de valider notre etude theorique en mode store and forward. La troisieme partie est consacree a l'etude du recouvrement des communications par des calculs. L'idee consiste a anticiper les communications, en pipelinant l'envoi de petits messages. Mais la taille des messages a envoyer n'est pas facile a calculer. Nous illustrons ce probleme sur l'exemple du produit matrice-vecteur.

There is a growing realisation from the Australian government that new models of health care will need to be developed to address the disparity of access, increasing demand and escalating cost of traditional means of delivering health care. There is growing evidence showing health care services can be delivered safely and efficiently by email. Despite this body of evidence the clinical utility of email is occurring at a much slower rate than in other business areas. Technological barriers and privacy risks are often cited as cause of the fragmented adoption and utilisation of email-based telemedicine. In addressing these impediments, the service-delivery application needs to be considered. The service-delivery applications used in email-based telemedicine can be divided into two distinct categories. The first is ordinary email applications — such as the commercial products used for personal communication — and the second is where the health care provider undertakes the development of an email application purpose-written to support their telemedicine service. This aim of this research was to develop a decision support model (DSM) to address the complex issues in choosing the service-delivery application most appropriate for an email service. Three areas which would influence a provider’s decision were identified — i) privacy and security ii) economics and ii) quality of service — and investigated. Most emails are sent in plain text across the Internet and pose a privacy risk. Encryption of the email message is used to mitigate the risk. Two means of encryption were investigated: public key infrastructure (PKI) used in conjunction with ordinary email and secure web-mail applications, which require the development of a purpose-written application. Decisive factors in choosing the most appropriate privacy-enhancing technology for an email-based service were identified by a number of means including: technical assessment of encryption models, literature review, survey of users of an email-based telemedicine service and analysis of client applications used in a telemedicine service. This investigation established that correspondent’s perception to privacy risk, email client application support of PKI, risk tolerance to human error and the technical skill are decisive factors in choosing privacy-enhancing technology. The survey respondents considered a privacy breach during email communication was either likely or very unlikely regardless of whether the communication was encrypted or not. Indicating correspondents are unlikely to comply with encryption especially if the technology is cumbersome. Although the population was of a limited demographic, there was a large proliferation (around 87%) of web-mail clients — for example, Hotmail and Gmail — amongst the users of email-based telemedicine services. Web-mail clients cannot be secured with PKI. Hence, assessment of client-email applications used by correspondents in telemedicine will influence the type of privacy-enhancing technology. Technical assessment of privacy-enhancing technology has identified human-error as a risk when using PKI. Secure web-mail obviates human-error. Therefore, tolerance to human-error risk will be decisive in choice of privacy-enhancing technology. PKI has received criticism for being user-unfriendly and requiring technical proficiency to use. This investigation has established the usability of secure web-mail is comparable to ordinary, unencrypted email. Indicating secure communication is feasible when services are not supported by technical expertise. The cost of providing an email-based service is influenced by the service-delivery application. To develop a purpose-written application will cost the heath care provider but staff may be able to work more efficiently because the resultant application contains telemedicine specific functionality that meet the exact requirements of the service. Staff resources to run an email-based telemedicine service using ordinary email were compared to staff resources to run the same service using a purpose-written application. The purpose-written application afforded a reduction of 3% in time for clinical staff. Ancillary staff savings were more pronounced with a 33% reduction in administrative staff time and a 21% reduction in supervisory staff time. A cost-minimisation analysis established at a workload of up to 5000 email consultations per annum it is more economical to the run the service with ordinary email. For higher workload volumes it is cheaper to run the service with a purpose-written application. The threshold of 5000 emails consultations is the point at which the higher initial development cost of a purpose- written application are offset by staff efficiencies. A sensitivity analysis established the most influential factor in the economic model was workload volume — development costs and variable costs had little influence on the threshold. Response time was established as a quality of service metric after investigation demonstrated increases in response time were strongly correlated with a decrease in utilisation rate. The response time to maximise the utilisation rate was 32h or less. Pre- and post- studies demonstrated a purpose-written application can reduce response times. Telemedicine specific functionality in a purpose-written application was also investigated. Conditions for a purpose-written application — for example, use of multi-disciplinary staff, a priority service model and continuum of care over multiple email exchanges — to be efficacious at reducing response times were established. The conditions identified in the privacy and security, economic and quality of service investigation were amalgamated into a DSM. The DSM was retrospectively tested by comparing the output of the model to a gold-standard of the actual service-delivery used by a number of subject organisations. When used to identify services that required a purpose-written application the DSM was 92% sensitive and 92% specific. The model was also tested prospectively and demonstrated 85% concordance from testers in the choosing the service-delivery application. Testing the DSM identified strengths for both ordinary email and purpose-written applications under different circumstances — indicating both are valid alternatives for email-based telemedicine. The individual requirements of a telemedicine service — for example, privacy requirements, participants, the workload volume, number of staff disciplines, mode of service — will dictate the choice of the most appropriate service-delivery application. Informed decision on when and why to use a service-delivery application has implications for the successful delivery of email-based telemedicine services because the choice of service-delivery application will affect: - The staff resources needed to run the service; - The capital cost of implementing a service; - The operating costs of running a service; - The response times to client emails which in turn, influences the utilisation of the service; - The privacy-enhancing technology which in turn, influences the usability and compliance to legislative and statutory requirements.