Estágio realizado na ALERT Life Sciences Computing, S.A. / Tese de mestrado integrado. Engenharia Informática e Computação. Faculdade de Engenharia. Universidade do Porto. 2009

Routing in highly dynamic wireless networks such as Vehicular Ad-hoc Networks (VANETs) is a challenging task due to frequent topology changes. Sustaining a transmission path between peers in such network environment is difficult. In this thesis, Previous Hop Routing (PHR) is poposed; an opportunistic forwarding protocol exploiting previous hop information and distance to destination to make the forwarding decision on a packet-by-packet basis. It is intended for use in highly dynamic network where the life time of a hop-by-hop path between source and destination nodes is short. Exploiting the broadcast nature of wireless communication avoids the need to copy packets, and enables redundant paths to be formed. To save network resources, especially under high network loads, PHR employs probabilistic forwarding. The forwarding probability is calculated based on the perceived network load as measured by the arrival rate at the network interface. We evaluate PHR in an urban VANET environment using NS2 (for network traffic) and SUMO (for vehicular movement) simulators, with scenarios configured to re ect real-world conditions. The simulation scenarios are configured to use two velocity profiles i.e. Low and high velocity. The results show that the PHR networks able to achieve best performance as measured by Packet Delivery Ratio (PDR) and Drop Burst Length (DBL) compared to conventional routing protocols in high velocity scenarios.

"Personal health record (PHR) service is an emerging model for health information exchange. It allows patients to create, manage, control and share their health information with other users as well as healthcare providers. In reality, a PHR service is likely to be hosted by third-party cloud service providers in order to enhance its interoperability. However, there have been serious privacy concerns about outsourcing PHR data to cloud servers, not only because cloud providers are generally not covered entities under HIPAA, but also due to an increasing number of cloud data breach incidents happened in recent years. In this thesis, we propose a privacy-preserving PHR system using attribute-based encryption (ABE). In this system, patients can encrypt their PHRs and store them on semi-trusted cloud servers such that servers do not have access to sensitive PHR contexts. Meanwhile patients maintain full control over access to their PHR files, by assigning fine-grained, attribute-based access privileges to selected data users, while different users can have access to different parts of their PHR. Our system also provides extra features such as populating PHR from professional electronic health record (EHR) using ABE. In order to evaluate our proposal, we create a Linux library that implement primitive of key-policy attribute-based encryption (KP-ABE) algorithms. We also build a PHR application based on Indivo PCHR system that allow doctors to encrypt and submit their prescription and diagnostic note to PHR servers using KP-ABE. We evaluate the performance efficiency of different ABE schemes as well as the data query time of Indivo PCHR system when PHR data are encrypted under ABE scheme."

There is a growing demand to involve patients in their own healthcare. Personal Health Records are among the most promising tools for this purpose. However, these tools need to meet patients’ needs and interests in order to be fully adopted and successfully used. This study takes a user centered design approach to design and develop a personal health record for prostate cancer patients by involving them in two main activities of a user centered design: requirements gathering and evaluation. The first phase of the study uses content analysis to analyze interviews with patients and elicit their needs and concerns. Results of this phase showed that patient’s information needs are different depending on the stage of the disease. Before starting treatment, patients are more interested in information about different methods of treatment and their potential side effects. However, after treatment, patients mostly need information about the management of treatment complications and the long term follow ups of their disease. Results also showed that the Internet is the most common information source for patients to find information. However, patients expressed concerns regarding the credibility and reliability of information they found on the Internet. The majority of patients also showed interest in accessing their medical records. However, some patients were concerned about the understandability of the information. Also, there was some concern regarding electronic access to medical records and security of personal data. The findings from phase one are used in phase two to modify a preliminary prototype of the system. In phase three, the modified prototype is evaluated by undergoing usability testing. Overall, the results of usability testing showed that the system was generally useful and easy to use. However, a number of issues were identified that could be resolved in the next iteration of its design and development. / Graduate / 0984

Although previous studies have considered the factors affecting other certification exam outcomes, they have not examined those that are related to performance on the Professional in Human Resources (PHR) exam. In response to that need, this study specifically investigates technology and training factors that affect self-efficacy and self-set goals, and through them, influence PHR certification exam results. The target population for the study consisted of recent examinees who had taken a formal PHR examination preparation class or used another form of exam preparation training. The survey results were analyzed using partial least squares modeling techniques, and mediation effects were then tested. The results demonstrated that PHR training self-efficacy affected PHR exam self-efficacy and self-set goals. These factors then had an impact on PHR exam scores. Also, the results of task-technology fit were indirectly related to PHR training self-efficacy through a multiple mediation model that included the instructional factor of time on task and the technology factor of perceived usefulness. Surprisingly, time spent on practice exam questions was found to be negatively related to PHR certification exam scores. Finally, instructional feedback indirectly affected outcomes through its positive relationship to self-set goals. The results of the research should help training professionals and examinees in structuring PHR exam training and preparation activities. They also suggest avenues for improving outcomes in other similar types of training.

This study is interested in properties of fungal transglycosylases, specifically Phr1, Phr2 and Crh2. These enzymes are involved in the remodelling of yeast cell walls due to their cleavage of structural donor polysaccharides and transfer of their fragments to the other acceptor (poly)saccharide molecules. The mammalian cells do not contain cell walls, nor cell wall transglycosylases, that´s why these enzymes are possible targets for antifungal agents. In this diploma thesis the effect of 67 commercially available inhibitors on Phr1 and Phr2 enzymes was studied by rapid screening. In the case of the Phr1 enzyme, two inhibitors showed a potential effect which was subsequently tested by size exclusion chromatography column incorporated into HPLC device. None of the inhibitors were found to have an inhibitory effect on Phr1 or Phr2 enzymes in contrast to DMSO in which all inhibitors were dissolved. The mode of action of Phr enzymes was also studied by thin layer chromatography and high performance liquid chromatography. The first method allowed to monitor the formation of products only in the later stages of the reaction, but more sensitive size exclusion chromatography showed the product formation at the beginning of the reaction. Phr1 cleaved the donor substrate near the non-reducing end and forms small fragments that are transfered to labeled acceptors during the whole reaction. Phr2 utilized random action pattern, thus creating products with higher molecular weight from the beginning of reaction. The effect of the polymerization degree of acceptor on it´s affinity with the Crh2 was also studied. The Michaelis-Menten constants showed no effect of acceptor lenght on the affinity between enzyme and substrate.

No description available.

Bacillus cereus (Bc) et Bacillus thuringiensis (Bt) sont deux espèces génétiquement proches. Bc est une bactérie pathogène que peuvent causer des gastro-entérites d’origine aliméntaire. Bt est une bactérie entomopathogène, dont le cycle de vie dans la larve d’insecte est contrôlé par des systèmes de quorum sensing, comme le système Rap/Phr, que régule processus tels que la sporulation, la formation de biofilm et la conjugaison. La présence des ces genès a été identifiée dans les plasmides, et ces eleménts ont été associés à l’adaptation des spécies dans sont niche ecologique. Le but de cette étude est de comprendre le rôle des plasmides dans ces bactéries. Pour la première étude l’insecte larvae, le niche privilegie de Bt, ont été infectées par souches de Bc et Bt, avec un contenu plasmidique diffèrent. Le fitness a été evallué par le comptage de cellules végétatives et spores dans quatre temps. Les souches de Bt et Bc ont été classées dans cinq groups par rapport à sont fitness. Dans ces groups le plasmide a affecté le fitness de la bactérie positive ou négativement. Les résultats ont démontré que les souches du group du B. cereus que reçoivent a pathogène plasmid ne est pas suffisant pour une augmentation effectif de la population bactérienne, i.e., coloniser l’hôte. La deuxième étude a permis caractériser le système rap/phr porté par le plasmide cryptique pHT8_1. Les résultats démontrent que la protéine Rap8 inhibe la sporulation dans la l’insecte. L’activité de cette protéine est inhibée par le peptide de signalisation Phr8. Le système Rap/Phr8_1 a permis les bactéries exercer un strict contrôle sur la sporulation, un processus important pour assurer la survie et la dissémination des bactéries. L’ensemble des résultats de la deuxième étude montrent que les plasmides peuvent fournir avantages pour l’adaptation et evolution de B. thuringiensis dans son niche ecologique, alors que les résultats de la première étude indiqués que les souches de Bc group doivent avoir un contenu génétique approprié pour exhiber un fitness élévé en permettant une optimal multiplication and dissemination de populations bactérienne dans l’insect larvae. / Bacillus cereus (Bc) and Bacillus thuringiensis (Bt) are two closely related species. Bc is a pathogenic species responsible for gastroenteritis by food-borne. Bt is an entomopathogenic bacterium, which the lifecycle in insect larvae is controlled by quorum sensing systems, such as Rap/Phr, which regulates processes such as sporulation, biofilm formation and conjugation. The presence of these genes in plasmids has been described, furthermore, plasmids have been involved in bacterial adaptation to their ecological niche. In order to understand the role of the plasmids to these species, two complementary works were carried out. First, insect larvae, a privileged ecological niche of Bt strains, were infected with Bc and Bt strains harboring different plasmid contents. Their fitness were evaluated by vegetative cells and spore counts at four time points. Bt and Bc strains were classified into five groups according to the bacterial fitness. In these groups, the plasmid affects positively or negatively the bacterial fitness. The results demonstrated that for B. cereus group strains, getting a pathogenicity plasmid is not enough to effectively increase bacterial population, colonizing insect hosts. The second study characterized the rap/phr system encoded by the cryptic plasmid pHT8_1. The Rap8 protein inhibited the sporulation process in insect larvae. This protein was directly inhibited by the active signaling peptide Phr8. The Rap8/Phr8 system may allow the bacteria to exert a tight control of the sporulation process in the host cadaver for optimizing the multiplication, the survival and the dissemination of the bacteria. Thus, the results of the second study showed that the plasmids can provide advantages for the adaptation and the evolution of B. thuringiensis in its ecological niche, while the results of the first study indicate that B. cereus group strains must have a suitable genetic background to display a high fitness allowing optimal multiplication and dissemination of the bacterial population within insect larvae.

Indiana University-Purdue University Indianapolis (IUPUI) / Acceptance of PHR by physicians is fundamental as they play important role towards the promotion of PHR adoption by providing the access to the data to be maintained in PHR and also, using the information within the PHR for decision making. Therefore it is important to measure physicians' perspective on usefulness of PHR, and also the value and trust they have in PHR usage. Review of previous researches identifies the lack of availability of a valid survey instrument that can be used to measure physicians' perception on all different aspects of PHR use and acceptance. Using the integrated literature review methodology and Unified Theory of Acceptance and Use of Technology (UTAUT) as a guiding framework, this study was aimed to identify the factors that can be used in the development of comprehensive evaluation instrument to understand physicians' acceptance of PHR. Total 15 articles were selected for literature review and using the content analysis method, 189 undifferentiated data units were extracted from those articles. These data units were then categorized into the four core constructs of UTAUT. ―Other categorization system was also created for the data units that could not be classified into one of the UTAUT core constructs. Among four core UTAUT constructs, Performance Expectancy is found to be the most influential factor in physicians' acceptance of PHR, followed by ―Other factors, Facilitating Condition and Social Influence. Effort expectancy was found to be the least influential. The identified specific factors within each domain can be used to develop a valid survey instrument to measure physicians' perception on PHR.

No description available.