Local Optimal Sets and Bounded Archiving on Multi-objective NK-Landscapes with Correlated Objectives

The properties of local optimal solutions in multi-objective combinatorial optimization problems are crucial for the effectiveness of local search algorithms, particularly when these algorithms are based on Pareto dominance. Such local search algorithms typically return a set of mutually nondominated Pareto local optimal (PLO) solutions, that is, a PLO-set. This paper investigates two aspects of PLO-sets by means of experiments with Pareto local search (PLS). First, we examine the impact of several problem characteristics on the properties of PLO-sets for multi-objective NK-landscapes with correlated objectives. In particular, we report that either increasing the number of objectives or decreasing the correlation between objectives leads to an exponential increment on the size of PLO-sets, whereas the variable correlation has only a minor effect. Second, we study the running time and the quality reached when using bounding archiving methods to limit the size of the archive handled by PLS, and thus, the maximum size of the PLO-set found. We argue that there is a clear relationship between the running time of PLS and the difficulty of a problem instance.Comment: appears in Parallel Problem Solving from Nature - PPSN XIII, Ljubljana : Slovenia (2014

Local Optimal Sets and Bounded Archiving on Multi-objective NK-Landscapes with Correlated Objectives

The properties of local optimal solutions in multi-objective combinatorial optimization problems are crucial for the effectiveness of local search algorithms, particularly when these algorithms are based on Pareto dominance. Such local search algorithms typically return a set of mutually nondominated Pareto local optimal (PLO) solutions, that is, a PLO-set. This paper investigates two aspects of PLO-sets by means of experiments with Pareto local search (PLS). First, we examine the impact of several problem characteristics on the properties of PLO-sets for multi-objective NK-landscapes with correlated objectives. In particular, we report that either increasing the number of objectives or decreasing the correlation between objectives leads to an exponential increment on the size of PLO-sets, whereas the variable correlation has only a minor effect. Second, we study the running time and the quality reached when using bounding archiving methods to limit the size of the archive handled by PLS, and thus, the maximum size of the PLO-set found. We argue that there is a clear relationship between the running time of PLS and the difficulty of a problem instance.Comment: appears in Parallel Problem Solving from Nature - PPSN XIII, Ljubljana : Slovenia (2014

Gamifying sustainability : raising carbon footprint awareness through gamification : the carbon footprint movement

Extreme human-induced environmental pressures are being felt across the globe. Scientific evidence increasingly alerts for the urgent need to induce societal engagement in climate change mitigation to achieve carbon-reduction targets. This thesis’ overreaching purpose aimed at appraising the extent to which a gamification-based system may increase carbon literacy and empower individuals to adopt lower-carbon lifestyles. Simultaneously, this study explores the hotspots where policy action should be taken to reduce the contextual barriers to more pro-environmental lifestyles. Given the multitude of factors influencing behaviors, the research herein described disaggregated national data to local levels. To attain the set objectives, a gamified-survey tool was developed, as the primary learning and data collection instrument: The Carbon Footprint Movement. Results showed carbon footprint was not a primary deliberation preceding everyday behavior and that respondents’ misconceptions regarding the environmental effects of their actions prevailed. Additional findings also reinforced contextual factors further detached intentions from behaviors, intensifying the so-called value-action gap. Notwithstanding, participants reported carbon literacy increases (23%) and pledged imminent behavioral changes, over the course of the intervention. This dissertation reinforces high-magnitude carbon emissions to be locked-in at the household level, and the potentiality of gamified interventions to unlock substantial reductions. However, it simultaneously unveils large potential savings to remain unfulfilled, suggesting active civic engagement also calls for wider structural adjustments The methodology devised might be used to guide the development of future gamified interventions.Pressões ambientais extremas estão a ser sentidas em todo o mundo. Evidências científicas alertam para a necessidade urgente do envolvimento da sociedade na mitigação das alterações climáticas. Esta dissertação visa avaliar em que medida um sistema baseado na gamificação pode aumentar a literacia de carbono e capacitar os indivíduos para adotarem comportamentos mais sustentáveis. Paralelamente, este estudo explora os pontos críticos em que devem ser tomadas medidas para a redução de obstáculos a estilos de vida mais pró-ambientais. Para atingir os objetivos estabelecidos, foi desenvolvido um instrumento de aprendizagem e de recolha de dados: The Carbon Footprint Movement. Os resultados indicam que a tomada diária de decisões raramente é precedida de uma deliberação sobre a respetiva pegada de carbono, que as pessoas mantêm ideias erradas sobre a eficácia ambiental das suas ações, e que os fatores contextuais desassociam ainda mais as intenções dos comportamentos. Não obstante, os participantes reportaram aumentos em literacia de carbono (23%) e afirmaram mudanças comportamentais ao longo da intervenção. Esta dissertação destaca a potencialidade de intervenções gamificadas na redução substancial de emissões de carbono, bloqueadas ao nível doméstico. No entanto, este estudo revela que um envolvimento cívico mais ativo no combate às alterações climáticas exige, simultaneamente, ajustes estruturais fundamentais. A metodologia descrita poderá ser utilizada para orientar o desenvolvimento de futuras intervenções gamificadas

LytR Inhibition, an Approach to Avoid Biofilm Formation in Streptococcus dysgalactiae subs. dysgalactiae

Biofilm is a sessile bacterial growth phenotype, characterized by the cells being enclosed in a self-produced matrix, and attached to a surface. This makes the biofilms less susceptible to antibiotics, making them hard to eliminate, leading to chronic infections. Streptococcus dysgalactiae subs. dysgalactiae (SDSD) is a Gram-positive bacterium with the ability to form biofilms and also, a known animal pathogen, responsible for causing bovine mastitis and fish streptococcosis. Both diseases represent huge losses for the diary and fish industries. It is, then, very important to develop drugs capable of inhibiting the production of biofilms of this bacterium. Teichoic acids are glycopolymers present in the cell wall of all Gram-positive bacteria. These molecules are very important in the early stages of biofilm development, as they participate in the attachment events. SDSD possesses a LytR protein, belonging to the LytR-CpsA-Psr (LCP) family of proteins, that is necessary for the attachment of the teichoic acids to the peptidoglycan, which makes this protein a good target for biofilm inhibition. In this thesis, the LCP domain of SDSD LytR, that contains the LCP domains was overexpressed, in E. coli BL21. Purification of the protein was performed with an IMAC and a SEC. The produced protein was used for crystallization experiments and for the biophysical characterization of the interaction of SDSD LytR with putative ligands/substrates/inhibitors, by thermal shift assay (TSA), circular dichroism (CD), urea gel electrophoresis and microscale thermophoresis (MST). In the course of this work, the three-dimensional structure of SDSD LytR was determined, for the first time, at a resolution of 2.80 Å. Improvement of the resolution was not successful, as well as, the co-crystallization experiments. The techniques used did not reveal binding of the protein towards the tested compounds. We suggest that it might be due to low affinity of the compounds towards SDSD LytR

Operational risk in the actuarial valuations of defined benefit pension schemes

Mestrado Bolonha em Actuarial ScienceOperational risk has always been a concern throughout history, especially since the 2008 financial crisis. Organisations, nowmore than ever, focus on excellence and regulation. Through the recognition of operational risk as an intrinsic part of organisations and an effective risk management strategy, operational risk can be leveraged as an advantage for organisations. UK law requires that, every three years, defined benefit pension schemes should be subject to an actuarial valuation. The goal of this is to provide a clear view of the scheme’s liability, which allows for a proper asset-liability management. As new technologies are developed, new challenges arise in terms of ensuring the maximum quality of results provided by actuarial valuations. In the context of a five-month curricular internship at Willis Towers Watson’s Lisbon subsidiary, which led to a deep exploration of actuarial valuations of defined benefit pension funds, I was given the project to do a deep study of the specific mechanisms in place to manage the operational risk and to guarantee the accuracy of the results produced. To present my findings, I simulated two types of errors, into a sample client: input errors (changes in the client’s data) and setup errors (changes in the information embedded into the internal software, used for the calculations). After simulating the errors, I saw how they could be identified using the internal mechanisms designed to prevent them. The overall conclusion is that the operational risk is well managed in the organisation, which contributes to the quality of the services provided.O risco operacional tem sido sempre uma preocupação ao longo da história, especialmente depois da crise financeira de 2008. As organizações, agora mais do que nunca, focam-se em excelência e regulação. Através do reconhecimento do risco operacional como uma parte intrínseca das organizações e de uma estratégia de gestão de risco eficaz, a correta gestão do risco operacional pode ser aproveitada como uma vantagem para as organizações. A lei do Reino Unido exige que, a cada três anos, os planos de pensões de benefício definido devem ser sujeitos a uma avaliação atuarial. O objetivo é providenciar uma visão clara dos passivos do fundo em questão, o que permite uma adequada gestão de ativos-passivos. À medida que se desenvolvem novas tecnologias, aparecem novos desafios em termos de garantir a máxima qualidade dos resultados providenciados pelas avaliações atuariais. No contexto de um estágio curricular de cinco meses na subsidiária lisboeta da Willis Towers Watson, que levou a uma exploração profunda de avaliações atuariais de planos de pensões de benefício definido, foi-me proposto que investigasse os mecanismos específicos em vigor para garantir a precisão dos resultados produzidos. Para ilustrar todo o processo, simulei dois tipos de erros, num cliente amostra: erros de input (mudanças nos dados do cliente) e erros de setup (mudanças na informação colocada nos softwares internos, usados para os cálculos). Uma vez a simulação feita, foi possível identificar os mecanismos internos desenhados para os prevenir. No geral, concluí que que o risco operacional é bem gerido na organização, contribuindo para a qualidade dos serviços providenciados.info:eu-repo/semantics/publishedVersio

A note on the ϵ-indicator subset selection

The ϵ-indicator subset selection selects a subset of a nondominated point set that is as close as possible to a reference point set with respect to the ϵ-indicator. This selection procedure is used by population-based heuristic approaches for multiobjective optimization problems. Given that this procedure is called very often during the run of the heuristic approach, efficient ways of computing the optimal subset are strongly required. In this note, we give a correctness proof of the ϵ-indicator subset selection algorithm proposed by Ponte et al. (2012) [1] for the bidimensional case as well as several algorithmic improvements in terms of time complexity. Extensions to larger dimension are also discussed

On a Cardinality Constrained Multicriteria Knapsack Problem

We consider a variant of a knapsack problem with a fixed cardinality constraint. There are three objective functions to be optimized: one real-valued and two integer-valued objectives. We show that this problem can be solved efficiently by a local search. The algorithm utilizes connectedness of a subset of feasible solutions and has optimal run-time