Nuno Sousa Pereira

Vaccine Supply: Effects of Regulation and Competition

Abstract In US vaccine markets, competing producers with high fixed, sunk costs face relatively concentrated demand. The resulting price and quality competition leads to the exit of all but one or very few producers per vaccine. Our empirical analysis of exits from US vaccine markets supports the hypothesis that high fixed costs and both price and quality competition contribute to vaccine exits. We find no evidence that government purchasing has significant effects, possibly because government purchase tends to increase volume but lower price, with offsetting effects. Evidence from the flu vaccine market confirms that government purchasing is not a necessary condition for exits and the existence of few suppliers per vaccine in the US.

TOO SICK TO START: ENTREPRENEUR’S HEALTH AND BUSINESS ENTRY IN TOWNSHIPS AROUND DURBAN, SOUTH AFRICA

Unlike large firms with management teams, small businesses are usually run by one key person, the owner-entrepreneur, who bears almost all of the risks and makes almost all of the decisions related to the business. Because the owner-entrepreneur also embodies most of the firm-specific knowledge capital, health of the owner-entrepreneur is an important factor in the production process. Following a cohort of respondents in townships around Durban, South Africa, over a three-year period, we examined the relationship between an individuals physical health and the decision to start a business. Our results suggest that respondents who were recent business entrants were in better health than respondents who did not start new businesses. Moreover, respondents without a business at the beginning of the study who later opened businesses during the three-year study interval were significantly more likely to have better baseline health than those respondents who never started a new business. Hence, good health among entrepreneurs seems to be an important prerequisite to small business entry.

Designing a Solver for Arithmetic Constraints to Support Education in Mathematics

We present a conditional rewrite system for arithmetic and membership univariate constraints over real numbers, designed for computer assisted learning (CAL) in elementary math. Two fundamental principles guided the design of the proposed rewrite rules: cognitive fidelity (emulating steps students should take) and correctness, aiming that step-by-step solutions to problems look like ones carried out by students. In order to gain more flexibility to modify rules, add new ones and customize solvers, the rules are written in a specification language and then compiled to Prolog. The rewrite system is complete for a relevant subset of problems found in high-school math textbooks.

Wireless sensor networks: 12th European conference, EWSN 2015 porto, portugal, february 9-11, 2015 proceedings

In recent years Wireless Sensor Networks (WSNs) have been deployed in wide range of applications from the health and environment monitoring to building and industrial control. However, the pace of prevalence of WSN is slower than anticipated by the research community due to several reasons including required embedded systems expertise for developing and deploying WSNs; use of proprietary protocols; and limits in scalability and reliability. In this paper we propose PyFUNS (Pythonbased Framework for Ubiquitous Networked Sensors) to address these challenges. PyFUNS handles low level and networking functionalities, using the services provided by Contiki, and leaves to the user only the task of application development in the form of Python scripts. This approach reduces required expertise in embedded systems to develop WSN based applications. PyFUNS also uses 6LoWPAN and CoAP standard protocols to enable interoperability and ease of integration with other systems, pursuing the Internet of Things vision. Through a real implementation of PyFUNS in two constrained platforms we proved its feasibility in mote devices, as well as its performance in terms of control delay, energy consumption and network traffic in several network topologies. As it is possible with PyFUNS to easily compare performance of different deployments of distributed application, PyFUNS can be used to identify optimal design of distributed application.