Improving downstream processing for viral vectors and viral vaccines

Viral vectors are playing an increasingly important role in the vaccine and gene therapy elds. The broad spectrum of potential applications, together with expanding medical markets, drives the e orts to improve the production processes for viral vaccines and viral vectors. Developing countries, in particular, are becoming the main vaccine market. It is thus critical to decrease the cost per dose, which is only achievable by improving the production process. In particular advances in the upstream processing have substantially increased bioreactor yields, shifting the bioprocess bottlenecks towards the downstream processing. The work presented in this thesis aimed to develop new processes for adenoviruses puri cation. The use of state-of-the-art technology combined with innovative continuous processes contributed to build robust and cost-e ective strategies for puri cation of complex biopharmaceuticals.(...)

Empirical evidences on voluntary delisting phenomenon

The paper studies what drives firms to voluntary delist from capital markets and what differs in firms’ behavior and fundamentals between public-to-private transactions and M&A deals with listed corporations. Moreover, I study the relationship between ownership percentage in controlling shareholders’ hands and cumulative returns around the delisting public announcement. I perform my tests both for the Italian and the US markets and I compare the findings to better understand how the phenomenon works in these different institutional environments. Consistent with my expectations, I find that the likelihood of delisting is mainly related to size, underperformance and undervaluation, while shareholders are more rewarded when their companies are involved in PTP transactions than in M&As with public firms.

The Portuguese contemporary art as an investment

In this paper we investigate what drives the prices of Portuguese contemporary art at auction and explore the potential of art as an asset. Based on a hedonic prices model we construct an Art Price Index as a proxy for the Portuguese contemporary art market over the period of 1994 to 2014. A performance analysis suggests that art underperforms the S&P500 but overperforms the Portuguese stock market and American Government bonds. However, It does it at the cost of higher risk. Results also show that art as low correlation with financial markets, evidencing some potential in risk mitigation when added to traditional equity portfolios.

Modeling and forecasting value-at-risk for the Portuguese stock market

The aim of this work project is to find a model that is able to accurately forecast the daily Value-at-Risk for PSI-20 Index, independently of the market conditions, in order to expand empirical literature for the Portuguese stock market. Hence, two subsamples, representing more and less volatile periods, were modeled through unconditional and conditional volatility models (because it is what drives returns). All models were evaluated through Kupiec’s and Christoffersen’s tests, by comparing forecasts with actual results. Using an out-of-sample of 204 observations, it was found that a GARCH(1,1) is an accurate model for our purposes.

Switching mode power amplifier for bluetooth applications

Modern fully integrated transceivers architectures, require circuits with low area, low cost, low power, and high efficiency. A key block in modern transceivers is the power amplifier, which is deeply studied in this thesis. First, we study the implementation of a classical Class-A amplifier, describing the basic operation of an RF power amplifier, and analysing the influence of the real models of the reactive components in its operation. Secondly, the Class-E amplifier is deeply studied. The different types of implementations are reviewed and theoretical equations are derived and compared with simulations. There were selected four modes of operation for the Class-E amplifier, in order to perform the implementation of the output stage, and the subsequent comparison of results. This led to the selection of the mode with the best trade-off between efficiency and harmonics distortion, lower power consumption and higher output power. The optimal choice was a parallel circuit containing an inductor with a finite value. To complete the implementation of the PA in switching mode, a driver was implemented. The final block (output stage together with the driver) got 20 % total efficiency (PAE) transmitting 8 dBm output power to a 50 W load with a total harmonic distortion (THD) of 3 % and a total consumption of 28 mW. All implementations are designed using standard 130 nm CMOS technology. The operating frequency is 2.4 GHz and it was considered an 1.2 V DC power supply. The proposed circuit is intended to be used in a Bluetooth transmitter, however, it has a wider range of applications.

Study of AC losses in medium-sized high temperature superconducting coils

The study of AC losses in superconducting pancake coils is of utmost importance for the development of superconducting devices. Due to different technical difficulties this study is usually performed considering one of two approaches: considering superconducting coils of few turns and studying AC losses in a large frequency range vs. superconducting coils with a large number of turns but measuring AC losses only in low frequencies. In this work, a study of AC losses in 128 turn superconducting coils is performed, considering frequencies ranging from 50 Hz till 1152 Hz and currents ranging from zero till the critical current of the coils. Moreover, the study of AC losses considering two different simultaneous harmonic components is also performed and results are compared to the behaviour presented by the coils when operating in a single frequency regime. Different electrical methods are used to verify the total amount of AC losses in the coil and a simple calorimetric method is presented, in order to measure AC losses in a multi-harmonic context. Different analytical and numerical methods are implemented and/or used, to design the superconducting coils and to compute the total amount of AC losses in the superconducting system and a comparison is performed to verify the advantages and drawbacks of each method.

Money never sleeps – overnight returns in equity markets

The present research analyses overnight returns’ outperformance in relation to daytime returns. In a first stage, it will be assessed whether these returns are robust throughout time, markets and across different scopes of analysis (e.g. weekdays, months, states of the economy). In a second stage, several hypothesis will be empirically tested, in an attempt to understand what drives non-trading period returns (e.g. liquidity, market volatility). Even though several authors have analysed overnight returns and suggested several explanatory factors, there seems to be no consensus in the literature regarding its drivers.

Asking why

The growth of a solid, knowledge-intensive firm, OutSystems—an IT company recognized in 2003 by Fortune magazine as one of the most promising start-ups in the world—is accompanied by efforts to create a strong culture that preserves the traits that have driven OutSystems’ success and that drives innovation, adaptability, high performance, and accountability. The lessons OutSystems learned from previous international experiences are presented along with its latest growth model of branded local partners. The case study is intended to introduce concepts related to organizational culture, traits of cultures that drive innovation, national versus organizational culture, and the challenges of globalization. It is designed to be used in Organizational Behavior classes and is appropriate for MBA- and Master’s-level courses in the area of management. It is suggested as a guideline for 60- to 90-minute classes. Participants are invited to discuss the importance of organizational cultures and their fit with the company strategy. Participants are also encouraged to brainstorm about the best approach to face OutSystems’ new stage of growth, specifically the advantages and consequences of growing as a metanational company. Finally, in the conclusion, the most relevant findings taken from the discussions proposed are revisited: The importance of an organizational culture adapted to the market needs and the potential of innovation behind metanational companies. Other considerations are made about: how the case illustrates the importance of leadership, group age, and group size in the process of building a culture; and how OutSystems’ culture solves the apparent contradiction behind adaptable culture.

Finding the hidden influencers

This thesis is a first step in the search for the characteristics of funders, and the underlying motivation that drives them to participate in crowdfunding. The purpose of the study is to identify demographics and psychographics that influence a funder’s willingness to financially support a crowdfunding project (WFS). Crowdfunding, crowdsourcing and donation literature are combined to create a conceptual model in which age, gender, altruism and income, together with several control variables, are expected to have an influence on a funder’s WFS. Primary data collection was conducted using a survey, and a dataset of 175 potential crowdfunders was created. The data is analysed using a multiple regression and provided several interesting results. First of all, age and gender have a significant effect on WFS, males and young adults until the age of 30 have a higher intention to give money to crowdfunding projects. Second, altruism is significantly positively related to WFS, meaning that the funders do not just care about the potential rewards they could receive, but also about the benefits that they create for the entrepreneur and the people affected by the crowdfunding project. Third, the moderation effect of income was found to be insignificant in this model. It shows that income does not affect the strength of the relationship between the age, gender and altruism, and WFS. This study provides important theoretical contributions by, to the best of my knowledge, being the first study to quantitatively investigate the characteristics of funders and using the funder as the unit of analysis. Moreover, the study provides important insights for entrepreneurs who wish to target the crowd better in order to attract and retain more funders, thereby increasing the chance of success of their project.

Comprehensive comparison of a current-source and a voltage-source converter for three-phase EV fast battery chargers

This paper presents a comprehensive comparison of a current-source converter and a voltage-source converter for three-phase electric vehicle (EV) fast battery chargers. Taking into account that the current-source converter (CSC) is a natural buck-type converter, the output voltage can assume a wide range of values, which varies between zero and the maximum instantaneous value of the power grid phase-to-phase voltage. On the other hand, taking into account that the voltage-source converter (VSC) is a natural boost-type converter, the output voltage is always greater than the maximum instantaneous value of the power grid phase-to-phase voltage, and consequently, it is necessary to use a dc-dc buck-type converter for applications as EV fast battery chargers. Along the paper is described in detail the principle of operation of both the CSC and the VSC for EV fast chargers, as well as the main equations of the power theory and current control strategies. The comparison between both converters is mainly established in terms of the total harmonic distortion of the grid current and the estimated efficiency for a range of operation between 10 kW and 50 kW.

Indicadores de "Hidricidade" como ferramenta de avaliação da eficiência urbana

One of the biggest challenges for urban space planners is to conciliate the indispensable demands of life with the forms of occupation of the territory. Among these demands is water. Population growth and urban sprawl are challenging water availability. Thus, it is important to evaluate development trends to predict future scenarios, enabling guide preventive actions and decision making. It is essential to have a practical and direct tool that allows us to transmit the necessary information. The objective of this study is to present a method for evaluating the urban efficiency in the process of city expansion and the availability of water supply. To do so, the indicators will be defined, called indicators of "hidricidade". As a result, it is expected to be obtained a direct and practical tool, that is going to allow to transmit the necessary information to the harmonic urban process planning, applicable to medium size Brazilian cities, allowing decision making as a guarantee of water supply and urban sprawl.

Spectrum-based energy leak localization

Dissertação de Mestrado em Engenharia Informática

The quantified-Self and wearable technologies in the workplace: implications and challenges for their implementations

Introduction of technologies in the workplace have led to a dramatic change. These changes have come with an increased capacity to gather data about one’s working performance (i.e. productivity), as well as the capacity to track one’s personal responses (i.e. emotional, physiological, etc.) to this changing workplace environment. This movement of self-monitoring or self-sensing using diverse types of wearable sensors combined with the use of computing has been identified as the Quantified-Self. Miniaturization of sensors, reduction in cost and a non-stop increase in the computer power capacity has led to a panacea of wearables and sensors to track and analyze all types of information. Utilized in the personal sphere to track information, a looming question remains, should employers use the information from the Quantified-Self to track their employees’ performance or well-being in the workplace and will this benefit employees? The aim of the present work is to layout the implications and challenges associated with the use of Quantified-Self information in the workplace. The Quantified-Self movement has enabled people to understand their personal life better by tracking multiple information and signals; such an approach could allow companies to gather knowledge on what drives productivity for their business and/or well-being of their employees. A discussion about the implications of this approach will cover 1) Monitoring health and well-being, 2) Oversight and safety, and 3) Mentoring and training. Challenges will address the question of 1) Privacy and Acceptability, 2) Scalability and 3) Creativity. Even though many questions remain regarding their use in the workplace, wearable technologies and Quantified-Self data in the workplace represent an exciting opportunity for the industry and health and safety practitioners who will be using them.

A sixth-order finite volume method for the 1D biharmonic operator: application to intramedullary nail simulation

A new very high-order finite volume method to solve problems with harmonic and biharmonic operators for one- dimensional geometries is proposed. The main ingredient is polynomial reconstruction based on local interpolations of mean values providing accurate approximations of the solution up to the sixth-order accuracy. First developed with the harmonic operator, an extension for the biharmonic operator is obtained, which allows designing a very high-order finite volume scheme where the solution is obtained by solving a matrix-free problem. An application in elasticity coupling the two operators is presented. We consider a beam subject to a combination of tensile and bending loads, where the main goal is the stress critical point determination for an intramedullary nail.

New control algorithm for single-phase series active power filter

This paper presents a single-phase Series Active Power Filter (Series APF) for mitigation of the load voltage harmonic content, while maintaining the voltage on the DC side regulated without the support of a voltage source. The proposed series active power filter control algorithm eliminates the additional voltage source to regulate the DC voltage, and with the adopted topology it is not used a coupling transformer to interface the series active power filter with the electrical power grid. The paper describes the control strategy which encapsulates the grid synchronization scheme, the compensation voltage calculation, the damping algorithm and the dead-time compensation. The topology and control strategy of the series active power filter have been evaluated in simulation software and simulations results are presented. Experimental results, obtained with a developed laboratorial prototype, validate the theoretical assumptions, and are within the harmonic spectrum limits imposed by the international recommendations of the IEEE-519 Standard.