Abstract
In this work, we introduce the concept of maximum curvature to separate the low from high reinfection levels. For each temporary immunity transition rate, the threshold value is the infection rate where the positive curvature of the endemic stationary state attains its maximum value. Hence, the maximum curvature reinfection threshold can be interpreted as the moment when the graph of the stationary state of infected attains the maximum change in its direction. When the temporary immunity transition rate tends to zero, the limiting point of the maximum curvature reinfection threshold coincides with the Gomes' reinfection threshold and the curvature blows up to infinity.

Abstract
In an avoidable harmful situation, autonomous vehicles systems are expected to choose the course of action that causes the less damage to everybody. However, this behavioral protocol implies some predictability. In this context, we show that if the autonomous vehicle decision process is perfectly known then malicious, opportunistic, terrorist, criminal and non-civic individuals may have incentives to manipulate it. Consequently, some levels of uncertainty are necessary for the system to be manipulation proof. Uncertainty removes the mis-behavior incentives because it increases the risk and likelihood of unsuccessful manipulation. However, uncertainty may also decrease the quality of the decision process with negative impact in terms of efficiency and welfare for the society. We also discuss other possible solutions to this problem.

Abstract

Abstract
Os artigos incluídos neste livro, após processo de revisão por pares, são desenvolvimentos de trabalhos apresentados nas JOCLAD 2014-17 e mostram, mais uma vez, a interdisciplinariedade e a diversidade das áreas que integram esta Jornadas.

Abstract
Background & aims: Bariatric surgery is increasingly common in the fight against morbid obesity. However, after this intervention, it is not fully understood the evolution of weight loss and how body composition changes. The objective of this work is to study the evolution after surgery of weight and body composition of obese patients that underwent bariatric surgery. Methods: In this retrospective and prospective study, we studied initially BMI and body composition of obese patients who attended nutritional appointments at Centro Hospitalar Sao Joao E.P.E. We collected personal data and anthropometric measurements between the pre-surgery appointment up to 60 months after surgery. Results: The sample consisted of 793 patients, of which 86.5% were female and 13.5% were male, with a mean age of 43 years (SD = 10.5 years) and mean height of 1.62 m (SD = 0.079 m). Patients undergoing gastric band, sleeve gastrectomy and gastric bypass had, respectively, an initial BMI reduction of 6.3 kg/ m(2), 13.2 kg/m(2) and 15.4 kg/m(2) and an initial fat mass% reduction of 4.4%, 14.3% and 17.3%. On the other hand, they had an initial increase of 3.2%, 10.8% and 12.4% of water%, 1.4%, 3.9% and 4.6% of fat and waterfree mass%, and 1.9%, 7.3% and 8.9% of skeletal muscle mass%, respectively. BMI and fat mass% on average had a large decrease in the first 12 months, increasing slightly from 24 months onwards. The opposite behaviour was observed for water%, fat and water-free mass% and skeletal muscle mass%. Conclusions: Bariatric surgery initially allows a substantial decrease in BMI as well as beneficial changes in the overall body composition of the individuals. Gastric bypass was the method that caused the most changes, followed by sleeve gastrectomy and, finally, gastric band. On average, after 24 months of follow-up, and for all surgical procedures studied, we observed a reversion in BMI and body composition values, showing the difficulties in maintaining weight and fat loss.

Abstract
In Portugal people aged 65 and above will be the populational group with the highest growth rate of the next decades. Healthy ageing constitutes a challenge as not only the number of years lived are essential, but also the quality of life becomes a priority. The aim of this study was to understand the relationship between health self-perception (HSP), food consumption and nutritional status among Portuguese older adults. Four hundred fifty-nine older adults (aged >= 65) were interviewed, almost half had a positive HSP. The most significant predictor of HSP was nutritional status, p = 0.005, but independence in shopping had the largest impact on how they compared to others, p < 0.001. Interventions need to focus on factors like nutritional status, independency on Activities of Daily Living, Satisfaction with Food-Related Life and utilize them to modify the negative HSP and attitudes towards ageing and health and maximize the positive aspects of old age.