Robust versus traditional methods for outlier detection in the simultaneous equations model

The Simultaneous Equation Model (SEM) is used for modelling real problems aris ing from Econometrics, Finance and other fields (see, for example, Greene [2003], Chen et al. [2007] or Lee et al. [2017]). The model is caracterized by a system of dependent equations whose coefficients can be estimated by methods like the Three Stages Least Squares (3SLS) or the Generalized Method of Moments (GMM). The corresponding estimators have nice properties but, unfortunately, they are not ro bust. Besides, outlier observations are particularly difficult to detect and interpret in the SEM and the use of non-robust estimators in the process reduces the confi dence on potential outlier detection analysis. We present a study that illustrates the use of a robust outlier detection method. The estimation of the coefficients of the model is performed with a robust version of the GMM. Outliers are interpreted and considered as outliers in the residuals, for the response variables, or as outliers in the explanatory variables. Identification of outlying points is based on the distribution of the robust Mahalanobis distances, computed with Minimum Covariance Determinant estimates and using a generalized inverse. The method is compared with outlier detection based on traditional non robust procedures, namely using Mahalanobis distances with the 3SLS, since the latter is a very popular estimator for the SEM parameters. A real data example with Econometric Portuguese data and a simulation study show the advantages of the robust proposal.publishe

Impact of the invasive argentine ant in citrus agroecosystems: effects on the diversity and frequency of native ant species foraging on tree canopy

The invasion of the Argentine ant, Linepithema humile (Mayr) (Hymenoptera, Formicidae) can alter the entire ecosystem with serious impacts on the native community structure (e.g., ant diversity) and processes (e.g., trophic interactions) leading to biodiversity loss and pest outbreaks. Most studies addressing these impacts have been conducted in natural or semi-natural areas, few are those conducted in agricultural ecosystems, such as citrus orchards. These are dominant agricultural ecosystems in Mediterranean landscapes. Furthermore, most studies have been conducted in a short span, not evidencing seasonal fluctuations. In this work, we assessed the ecological impact of the Argentine ant on the native ant communities in citrus orchards, in the region of Algarve, southern Portugal. By using principal response curve, we compared seasonal variation on ant assemblages in invaded and uninvaded citrus orchards foraging on tree canopy from a two-year sampling. The Argentine ant had a marked negative impact on the native ant community foraging on citrus canopy. In the uninvaded orchards, the native ant community had a rich assemblage composed of 16 ant species, in its majority (72%) controlled by the dominant species Lasius grandis Forel, Tapinoma nigerrimum (Nylander) and/or Pheidole pallidula (Nylander). In the invaded orchards, the native ant community was poorer and highly modified, mostly dominated by the Argentine ant (80%). Apparently, the only native ant species not a ected by the presence of the Argentine ant was Plagiolepis pygmaea (Latreille). A significant negative e ect was found between the proportion of infested trees by L. humile and the number of native ant species per orchard. Di erences in the native ant community in the invaded and uninvaded orchards persisted over seasons and years. However, negative impacts were higher in the spring and summer, and less pronounced in the autumn. We discuss implications for citrus pest managementinfo:eu-repo/semantics/publishedVersio

Os sais nas edificações

Dentre os problemas patológicos que prejudicam as edificações, especialmente as paredes em alvenarias e blocos cerâmicos, destacam-se aqueles causados pela umidade e salinidade. O dano provocado, normalmente, é o esfarelamento da superficie, quer seja de argamassa de reboco ou de blocos cerâmicos aparentes. Isto é gerado pelo fenômeno do aumento de volume de alguns sais, principalmente daqueles que têm elevada higroscopicidade e grande solubilidade. Várias são as fontes de origens dos sais. Eles existem na natureza, podem ser produzidos pelo homem nas atividades industriais ou até mesmo surgirem através da mistura de alguns materiais de construção. Por razões de ordem construtiva, os edificios mais afetados são os de construção antiga, numa época em que o Cimento Portland ainda não era utilizado. Motivo pelo qual as edificações apresentavam paredes com grande espessura. Todavia, nas construções contemporâneas, este mesmo problema é ocasionado, na maioria dos casos, por uma impermeabilização das fundações ausente ou de má execução. Este trabalho aborda aspectos referentes aos elementos acima citados

Surdez, análise das narrativas surdas em contexto escolar

187 f.Tendo em atenção que as dificuldades na leitura e na escrita são uma das causas do insucesso escolar da maioria das crianças surdas a nossa investigação centra-se no estudo dos motivos que podem influenciar o seu desenvolvimento linguístico na Língua Portuguesa. Conscientes da necessidade de limitarmos o campo de investigação, focalizamos a nossa atenção na influência que as modalidades linguísticas e as metodologias de ensino têm nas narrativas dos alunos surdos em contexto escolar. Como tal no enquadramento teórico abordamos conceitos, ideias, princípios que de uma forma ou de outra estão relacionados com a educação de surdos nomeadamente as que derivam do novo paradigma sócio antropológico com relevo para a situação portuguesa. Numa tentativa de arranjar uma amostra significativa e diversificada desenvolvemos o nosso trabalho em cinco escolas com o total de 51 alunos, 23 de modalidade linguística oral e 28 de Língua Gestual Portuguesa e ainda recolhemos entrevistas com 15 professores. Fizemos a aplicação de uma prova de linguagem escrita que foi um dos instrumentos usados para dar resposta à nossa pergunta de partida. Avaliámos individualmente o desempenho linguístico e tentamos esboçar uma comparação desse desempenho entre dois grupos. A análise dos resultados obtidos permite-nos apontar a permanência de grandes lacunas nas produções narrativas das crianças surdas levando-nos a questionar as metodologias e opções usadas na sua educação. a confrontação da informação recolhida e a sua análise confrontada com as leituras efectuadas e com a nossa experiência profissional, teve como intenção perceber os contextos actuais no sentido de ajudar a encontrar novas respostas para as dificuldades dos surdos

Modelling the invasion dynamics of the African citrus psyllid: The role of human-mediated dispersal and urban and peri-urban citrus trees

The African citrus psyllid, Trioza erytreae (Del Guercio) (Hemiptera, Triozidae), is native to tropical Africa and invasive species in North America and Europe. The main host plants are citrus, displaying a preference for lemon trees. This psyllid was recently detected in the northwest region of the Iberian Peninsula, both in Spain and Portugal. Here, we used a model combining a reaction-diffusion model to a stochastic long- distance dispersal model to simulate the invasion dynamics of T. erytreae in Portugal. The psyllid spread in Portugal was simulated between 2015 and 2021 for different combinations of model parameters: two fecundity levels; spread with and without stochastic long-distance dispersal; single or two introductions of T. erytreae; and considering or not the urban and peri-urban citrus trees, besides citrus orchards, estimated using Google Street view imagery. The incorporation of long-distance human mediated dispersal significantly improved the F1-score in the model validation using the official reports as the observed data. Concomitantly, the dispersal rate of T. erytreae in Portugal was on average about 66 km/year, whereas removing long-distance dispersal events, the observed mean was 7.8 ± 0.3 km/year. The dispersal was mainly towards the south along the coastline, where human population is concentrated. The inclusion of the estimated citrus trees outside orchards areas significantly increased the F1-score in the model validation, revealing the importance these isolated host plants hold as stepping stones for the species current invasion and possibly for other species alikeinfo:eu-repo/semantics/publishedVersio

Modelling Monochamus galloprovincialis dispersal trajectories across a heterogeneous landscape to optimize monitoring by trapping networks

Context 14 The pine wood nematode (PWN), is an invasive species which was introduced into Europe in 15 1999. It represents a major economic and ecological threat to European forests. In Europe, the 16 maritime pine is the main host and Monochamus galloprovinciallis is its only vector. 17 18 Objectives 19 Our goal was to analyze the effect of landscape heterogeneity on the vector’s dispersal. We 20 further aimed at developing a new method to locate the origin of insects captured in a systematic 21 network of pheromone traps. 22 23 Methods 24 A mark-release-recapture experiment was carried out in a heterogeneous landscape combining 25 maritime pine plantations, clear-cuts and isolated patches of broadleaved and mixed forests in 26 the southwest of France. 27 Least-cost path analysis was used to model dispersal trajectories and assign friction values to 28 each land-use type in the landscape. We used the trap’s geographical coordinates, capture levels 29 and mean friction values of neighbouring patches to calculate a weighed barycentre and the 30 position of the release of marked beetlesinfo:eu-repo/semantics/submittedVersio

Do dominant native ants outcompete the invasive Argentine ant in Mediterranean citrus ecosystems? A laboratory test

The invasive Argentine ant (Linepithema humile) poses a significant threat to ecosystem stability worldwide. In Mediterranean citrus ecosystems, its spread may be limited by interactions with dominant native ant species. We conducted laboratory experiments to investigate the competitive dynamics between Argentine ants and two major native species, Tapinoma nigerrimum and Lasius grandis. At the individual level, both native species exhibited superior competitive performance, attributed to their larger body sizes and potential differences in chemical defences. At the colony level, T. nigerrimum demonstrated efficiency in interference competition, successfully defending food resources from Argentine ants. However, the Argentine ant exhibited higher recruitment capacity, albeit it was density-dependent. Our findings support the hypothesis that dominant native ants can serve as barriers against Argentine ant invasion in citrus ecosystems, highlighting the importance of interspecific competition in shaping community dynamics and invasive species management. This study underscores the potential role of native ant species in mitigating the impacts of invasive ants on ecosystem functioning and biodiversity conservation in agricultural landscapes, offering valuable insights for invasive species management strategies in Mediterranean citrus ecosystemsinfo:eu-repo/semantics/publishedVersio

A influência da musica no comportamento do consumidor no ambiente de compra

Na busca incessante do mercado consumidor em atrair cada vez mais clientes, a versatilidade se auto-intitula como paradigma para alcançar esse sucesso. As empresas utilizam métodos diversos e correm atrás do que podemos chamar de diferencial. A música tem em sua essência a capacidade de influenciar e ainda, descrever, de certa forma, o perfil, o estilo e até a personalidade das pessoas.Sendo assim, não é difícil imaginar acerca do comportamento das pessoas e de que forma a música influencia o consumidor. É possível acompanhar esse comportamento e o seus resultados quando observados de forma sistemática durante um determinado espaço de tempo. É bem verdade que para auferir o sucesso e conseguir manter-se nele, é necessário muito mais que colocar “cd player ” para tocar, mas sim ter a sensibilidade de percepção de clientes e de tudo em sua volta para então saber que estilo de música colocar, para quem colocar, quando e em que volume. Ao obter tal sensibilidade é possível traçar métodos, que foram comprovados por esta pesquisa, que a música influencia o comportamento do consumidor levando-o de forma induzida a conhecer, se interessar, ousar e por fim consumir

Os bairros pericentrais autoproduzidos de Maputo

Tese de Doutoramento em Urbanismo, apresentada na Faculdade de Arquitetura da Universidade de Lisboa para obtenção do grau de Doutor.N/

Valorização do glicerol a bio-aditivos com catalizadores heterógeneos

O aumento da produção e utilização do biodiesel tem resultado num aumento da quantidade de glicerol produzida. Torna-se assim, imperativo desenvolver novas utilizações para o glicerol, de forma a evitar problemas ambientais. Uma possibilidade é a condensação do glicerol com acetona. Esta reacção foi realizada com ácido dodecatungstofosfórico (PW) imobilizado em SBA-15, a 70 ºC. Os catalisadores foram preparados com diferentes quantidades de heteropoliácido (1,8-10,8 wt.%). Observou-se que a actividade catalítica aumenta com a quantidade de PW imobilizada em SBA-15, sendo o catalisador PW4-SBA-15 (com 10,8 wt.%) a amostra mais activa. Todos os catalisadores apresentaram bons valores de selectividade para Composto A (cerca de 99% próximo da conversão completa). A estabilidade catalítica da amostra PW4-SBA-15 foi avaliada através da realização de três ensaios consecutivos. Observou-se que, após a terceira utilização, a actividade catalítica estabilizou. Foi também observado uma pequena lixiviação do heteropoliácido para a acetona; ### Abstract: The increase of use and production of biodiesel has resulted in an increase of glycerol. It is imperative to develop new uses for glycerol to prevent environmental problems. A possibility, it is the condensation of glycerol with acetone. This reaction was carried out using dodecatungstophosphoric acid (PW) immobilized in SBA-15, at 70ºC. A series of catalysts, with different heteropolyacid loading (from 1.8 to 10.8 wt. %), were prepared. It was observed that the catalytic activity increases with the amount of PW immobilized in SBA-15, being the PW4-SBA-15 (with 10.8 wt. %) the most active sample. All catalyst exhibited good values of selectivity to Composto A (about 99% near complete conversion). Catalytic stability of the PW4-SBA-15 was evaluated by performing consecutive batch runs with the same catalyst sample. It was observed that, after the third use, the catalytic activity stabilized. It was also observed a small leaching of heteropolyacid from SBA-15 to acetone