Construction of a real vehicular delay-tolerant network testbed

Vehicular Delay-Tolerant Networks (VDTNs) appear as innovative network architecture, able to outline communication challenges caused by issues like variable delays, disruption and intermittent connectivity once that it utilizes the store-carry-and-forward method to allow that in-transit messages (called bundles) can be delivered to the destination by hopping over the mobile vehicles even that an end-to-end path does not exist. Since messages are stored persistently in a buffer and forward to the next hop, a new communication infrastructure is created allowing low-cost asynchronous opportunistic communication under the most critical situations like variable delays and bandwidth constraints. VDTN introduces a layered architecture, acting as an overlay network over the link layer, aggregating incoming IP packets in data bundles (large IP packets), using out-of-band signaling, based on the separation of the control plane and planes. This dissertation presents and evaluates the performance of a real VDTN testbed, demonstrating the real applicability of this new vehicular communication approach. It includes an embedded VDTN testbed created to evaluate safety systems in a real-world scenario. It was used cars with laptops to realize terminal and relay nodes. A real testbed is very important because some complex issues presented in vehicular communication systems can be treated with more realism in real-world environments than in a laboratory environment. The experiments were performed on the internal streets of Brazilian Fiat Automobile manufacturing plant. Performance measurements and analysis were also conduct to verify the efficiency of the system. The results obtained show that safety applications and services can be executed with the actual proposal VDTN architecture in several environments, although notable interference as fading and characteristics of the radio channel, require the use of more modern, appropriate and robust technologies. Thus, the real deployment of VDTNs confirms that VDTNs can be seen as a very promising technology for vehicular communications.Fundação para a Ciência e a Tecnologia (FCT

Eye Tracking Methods for Analysis of Visuo-Cognitive Behavior in Medical Imaging

Predictive modeling of human visual search behavior and the underlying metacognitive processes is now possible thanks to significant advances in bio-sensing device technology and machine intelligence. Eye tracking bio-sensors, for example, can measure psycho-physiological response through change events in configuration of the human eye. These events include positional changes such as visual fixation, saccadic movements, and scanpath, and non-positional changes such as blinks and pupil dilation and constriction. Using data from eye-tracking sensors, we can model human perception, cognitive processes, and responses to external stimuli. In this study, we investigated the visuo-cognitive behavior of clinicians during the diagnostic decision process for breast cancer screening under clinically equivalent experimental conditions involving multiple monitors and breast projection views. Using a head-mounted eye tracking device and a customized user interface, we recorded eye change events and diagnostic decisions from 10 clinicians (three breast-imaging radiologists and seven Radiology residents) for a corpus of 100 screening mammograms (comprising cases of varied pathology and breast parenchyma density). We proposed novel features and gaze analysis techniques, which help to encode discriminative pattern changes in positional and non-positional measures of eye events. These changes were shown to correlate with individual image readers' identity and experience level, mammographic case pathology and breast parenchyma density, and diagnostic decision. Furthermore, our results suggest that a combination of machine intelligence and bio-sensing modalities can provide adequate predictive capability for the characterization of a mammographic case and image readers diagnostic performance. Lastly, features characterizing eye movements can be utilized for biometric identification purposes. These findings are impactful in real-time performance monitoring and personalized intelligent training and evaluation systems in screening mammography. Further, the developed algorithms are applicable in other application domains involving high-risk visual tasks

Evaluating forest species response to different climate conditions as a base for sustainable forest management under climate change

Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia / ULTo anticipate European climate scenarios for the end of the century, we explored the climate gradient within the REINFFORCE (RÉseau INFrastructure de recherche pour le suivi et l’adaptation des FORêts au Changement climatiquE) arboreta network, established in 38 sites between latitudes 37◦ and 57◦, where 35 tree species are represented. Understanding how climate affects tree phenology, biotic and abiotic vulnerability, is a most important research subject under Climate Change. We focused on determining which climatic variables best explain their survival and growth, and identify which species that are more tolerant to climate variation and those whose growth and survival future climate might constrain. We used empirical models to determine the best climatic predictor variables that explain tree survival and growth, to predict the impact on the specific response of tree species to changing climate scenarios, to evaluate the loss and assess the risk of maintaining or changing species, under each scenario. Considering the scenarios described on IPCC’s Fifth Assessment Report, predictions were run under two main Representative Concentration Pathways (RCP) 4.5 and 8.5. Precipitation-transfer distance was most important for the survival of broadleaved species, whereas growing-season-degree days best explained conifer-tree survival. Growth (annual height increment) was mainly explained by a derived annual dryness index (ADI) for both conifers and broadleaved trees. Species that showed the greatest variation in survival and growth in response to climatic variation included Betula pendula Roth, Pinus elliottii Engelm., and Thuja plicata Donn ex D.Don, and those that were least affected included Quercus shumardii Buckland and Pinus nigra J.F.Arnold. We also demonstrated that provenance differences were significant for Pinus pinea L., Quercus robur L., and Ceratonia siliqua L. A higher survival risk is expected for conifer species, especially for species like Calocedrus decurrens, Pseudotsuga menziesii, and Pinus nigra. For growth, high risk is indicated for Larix decidua, Pinus pinaster, and Betula pendula. Risk distribution points to higher risk at southern sites, and higher production potential for northern sites. Here, we demonstrate the usefulness of infrastructures along a climatic gradient like REINFFORCE to determine major tendencies of tree species responding to climate changesN/

Decision Making Under Scarcity: An Inquiry into The Effects of Cognitive Load

Scarcity, or the feeling of having less than you need, alters the decision-making process. This poverty-triggered mechanism makes economic decisions more difficult by curtailing cognitive control. This involuntary load redirects the deliberative part of the cognitive system towards making rational choices for scarcity alleviation. At the same time, other preferences get overwhelmingly guided by the affective system. Such recalibration results in the rational-bias split or tunnelling in preferences. Pressed for resources, people become judicious about relevant commitments as other beneficial but irrelevant choices suffer. This sensitivity to ‘what matters’ changes preferences. My work investigates this dichotomy of preferences. I look at financial scarcity and intimate partner violence as sources of cognitive load and examine split and changes in probability weighting function and risk preferences through the attentional mechanism. I undertook two lab-in-field experiments in Uganda and the Dominican Republic to investigate this framework. To understand the within-subject differences, each participant takes two decisions- one relevant to resolve the scarcity at hand and the other that is not. I use the common consequence ladders to track probability weighting, Eckel Grossman and Holt-Laury price lists for risk preferences. I confirm the pervasive characteristics of scarcity. Finances are a constant worry for those facing shortages. The level of scarcity affects cognitive load: inhibitory control and attention are taxed by expected scarcity. Working memory scores are affected by unexpected scarcity and the interaction of expected and shock. Additionally, previous experience of economic abuse, higher inhibitory control, and attention risk seeking. Finally, the scarcity-irrelevant probability weighting function is more likely to be non-linear than that for the scarcity-relevant attribute. I show that split or tunnelling depends on the strength of the top-down force of scarcity, the bottom-up force from the choice and their congruence. I find a by-scarcity-relevance split in probability weighting and risk preferences

Community Perspectives, Language Ideologies, and Learner Motivation in Chickasaw Language Programs

This study examines language ideologies in the Chickasaw Nation of Oklahoma, in the context of various efforts to revitalize this Muskogean language. There are approximately sixty-five remaining first language speakers out of a total population of about 57,000 tribal citizens. I analyze the underlying discourses in the community about the importance of preserving the language. I argue that these discourses are part of a broader project of nation-building meant to foster tribal citizens’ sense of identity, while demonstrating the relevance of the Chickasaw Nation to the state of Oklahoma and to the United States. These discourses justify the necessity of language revitalization to the Chickasaw community and to the larger society. This study examines people’s responses to these initiatives and discourses, and their general understanding, views, and aspirations regarding language revitalization. In particular, I examine their motivation to learn Chickasaw and the challenges of motivating other people to become learners. I argue that positive attitudes towards a language and access to resources do not automatically translate into action to learn it. I also review people’s views on bilingualism in English and Chickasaw, and their attitudes towards schools and homes as sites of language revitalization. I conclude that boosting people’s positive attitudes towards an endangered language is an important first step towards language revitalization, but that much remains to be done in terms of producing conversationally proficient second language speakers to recreate a speech community