Conditional tests for elliptical symmetry using robust estimators

This paper presents a procedure for testing the hypothesis that the underlying distribution of the data is elliptical when using robust location and scatter estimators instead of the sample mean and covariance matrix. Under mild assumptions that include elliptical distributions without first moments, we derive the test statistic asymptotic behaviour under the null hypothesis and under special alternatives. Numerical experiments allow to compare the behaviour of the tests based on the sample mean and covariance matrix with that based on robust estimators, under various elliptical distributions and different alternatives. This comparison was done looking not only at the observed level and power but we rather use the size-corrected relative exact power which provides a tool to assess the test statistic skill to detect alternatives. We also provide a numerical comparison with other competing tests.Comment: In press in Communications in Statistics: Theory and Methods, 201

Exploring the benefits of using a mixed methods approach in destination image studies

This study aims to demonstrate that mixed-methods are suitable when assessing the image of a tourism destination. Depict the image attributes that influence a lake destination area and conceptualize lake tourism are the goals of this study. Lake tourism is a growing academic field of tourism studies. However, little attention has been given to tourism images. The case is the newly-formed Alqueva Lake, Portugal, the biggest man-made lake in Europe. A mixed-design method was adopted, particularly a complementarity approach. The data were first collected in the qualitative stage, then analysed. Results were used to develop a follow-up questionnaire. A set of image attributes that best describe Alqueva Lake was obtained and validated. The advantages of adopting mixed-methods to studies about destination image are discussed

Primary Metabolite Adjustments Associated With Pinewood Nematode Resistance in Pinus pinaster

Original ResearchThe pinewood nematode (PWN) Bursaphelenchus xylophilus is the causal agent of the pine wilt disease (PWD) and represents one of the major threats to conifer forests. The detection of the PWN in Portugal, associated with Pinus pinaster, increased the concern of its spread to European forests. Despite its susceptibility to PWD, genetic variability found among P. pinaster populations has been associated with heritable PWD resistance. Understanding the mechanisms underlying tree resistance constitutes a valuable resource for breeding programs toward more resilient forest plantations. This study investigated changes in anatomy, chlorophyll a fluorescence (ChlF), and primary metabolism in susceptible and resistant P. pinaster half-sib plants, after PWN inoculation. Susceptible plants showed a general shutdown of central metabolism, osmolyte accumulation, photosynthetic inhibition, and a decrease in the plant water status. The ChlF transient rise (OJIP curve) revealed the appearance of L- and K-bands, indicators of environmental stress. In contrast, resistant plants revealed a regulated defense response and were able to restrict PWN migration and cellular damage. Furthermore, the accumulation of g-aminobutyric acid (GABA) and succinate suggested a role of these metabolites in PWD resistance and the possible activation of the GABA shunt. Altogether, these results provide new insights to the role of primary metabolism in PWD resistance and in the selection of resistant phenotypes for disease mitigationinfo:eu-repo/semantics/publishedVersio

Antimicrobial activity of phenolic extracts of Eucalyptus globulus and Juglans regia against dairy industry pathogens

Book of Abstracts of CEB Annual Meeting 2017[Excerpt] Bovine mastitis (BM) is the most expensive pathology for dairy industry and Staphylococcus aureus is amongst the most prevalent causative agents of this disease. Nowadays, it is known that S. aureus contaminated milk can enter the dairy production chain and be the origin of food contamination. Due to the poor efficacy of antibiotics and to the ability to form biofilms evidenced by this pathogen, BM has become increasingly difficult to control and to eradicate. Phenolic plant extracts are nowadays being evaluated since they are a rich source of bioactive molecules. Thus, in this work the antimicrobial activity of E. globulus and J. regia alone and in combination against S. aureus BM isolates was evaluated and compared with penicillin G (Pen G), an antibiotic commonly used in the treatment of this pathology. The evaluation of the cytotoxic potential of both extracts was also performed. [...]info:eu-repo/semantics/publishedVersio

Uso de medicamentos em gestantes

Antecedentes/Objetivos: O uso de medicamentos por gestantes deve ser considerado um problema de saúde pública (Carmo, 2003; Baldon et al, 2006). É um comportamento de alto risco terapêutico com elevados riscos potenciais, sobretudo, para o feto, mas também para a gestante (Olesen et al, 1999; Oliveira & Fonseca, 2006). Os efeitos sobre o feto dependem do fármaco ou substância, da paciente, da época de exposição durante a gestação, da frequência e da dose total, resultando potencialmente em teratogenia ou com consequências farmacológicas e toxicológicas diversas (Sorensen & De Jong-Van, 1997). Foram objetivos desta investigação determinar a prevalência do uso de medicamentos por gestantes em 2 Centros Hospitalares do Norte de Portugal, avaliando se existe relação entre as características maternas, fonte de indicação e os resultados obtidos pelas gestantes na sua experiência com medicamentos. Métodos: Trata-se de um estudo quantitativo transversal, observacional e analítico. A recolha de dados foi feita de Março a Maio de 2012. Todas as gestantes foram convidadas a participar, independentemente, do tempo de gestação. Participaram, nesta investigação, 125 gestantes. Resultados: Verificou-se que 79,2% das gestantes declararam utilizar pelo menos um medicamento, destas 5,1% fizeram-no sem prescrição médica. O Ferro (45%) e o Ácido Fólico (25%) foram os mais consumidos, porém, medicamentos considerados de risco para o feto também foram utilizados, nomeadamente, Atarax (2%), Minocin (1%), Omeprazol (1%), Amoxicilina (1%) e Cartia (1%). O trimestre gestacional foi o único parâmetro que registou diferenças na toma de medicação, sendo que foram as gestantes que se encontravam no terceiro trimestre de gravidez as que mais recorreram ao consumo de medicamentos (85,3%). Conclusiones: Embora o consumo de medicamentos durante a gestação seja uma realidade, esta tendência tem vindo a diminuir ao longo dos anos. Como medidas a serem tomadas na tentativa de reduzir o consumo de medicamentos não prescritos, sugere-se a realização de campanhas educativas em saúde e a partilha de informação que alerte para os riscos e contraindicações, bem como, a orientação sobre medidas alternativas não farmacológicas que poderão ser adotadas pelas gestantes

Origin and evolution of surface spin current in topological insulators

The Dirac surface states of topological insulators offer a unique possibility for creating spin polarized charge currents due to the spin-momentum locking. Here we demonstrate that the control over the bulk and surface contribution is crucial to maximize the charge-to-spin conversion efficiency. We observe an enhancement of the spin signal due to surface-dominated spin polarization while freezing out the bulk conductivity in semiconducting Bi1.5Sb0.5Te1.7Se1.3 below 100K. Detailed measurements up to room temperature exhibit a strong reduction of the magnetoresistance signal between 2 and 100K, which we attribute to the thermal excitation of bulk carriers and to the electron-phonon coupling in the surface states. The presence and dominance of this effect up to room temperature is promising for spintronic science and technology

An optimal control problem applied to a wastewater treatment plant

This paper aims to present a mathematical model that describes the operation of an activated sludge system during one day. Such system is used in the majority of wastewater treatment plants and depends strongly on the dissolved oxygen, since it is a biological treatment. To guarantee the appropriate amount of dissolved oxygen, expensive aeration strategies are demanded, leading to high costs in terms of energy consumption. It was considered a typical domestic e uent as the wastewater to test the mathematical model and it was used the ASM1 to describe the activated sludge behaviour. An optimal control problem was formulated whose cost functional considers the trade-o between the minimization of the control variable herein considered (the dissolved oxygen) and the quality index that is the amount of pollution. The optimal control problem is treated as a nonlinear optimization problem after discretization by direct methods. The problem was then coded in the AMPL programming language in order to carry out numerical simulations using the NLP solver IPOPT from NEOS Server.publishe

Pretreatments applied to microalgae residues to enhance anaerobic digestion

ABSTRACT: Biomass of microalga Chlorella protothecoides, grown under autotrophic and heterotrophic conditions and subjected to pretreatments, were energetically valorized through anaerobic digestion process according to the substrates: autotrophic algae (A), heterotrophic algae (H), heterotrophic algae extracted (HE), autoclave pretreated heterotrophic algae (HPA), enzyme pretreated heterotrophic algae (HPE), ultrasound pretreated heterotrophic algae (HPU), and inoculum (I). Despite the application of pretreatments, the highest methane production was obtained in the algae extracted digestion with 172 mL CH4, against 153, 126 and 142 mL obtained in HPA, HPE and HPU, respectively. The COD removal capacity was higher in the HPA sample while the TS and VS removal reached higher values in the autotrophic alga.N/

Overview on the antimicrobial activity and biocompatibility of sputtered carbon-based coatings

Due to their outstanding properties, carbon-based structures have received much attention from the scientific community. Their applications are diverse and include use in coatings on self-lubricating systems for anti-wear situations, thin films deposited on prosthetic elements, catalysis structures, or water remediation devices. From these applications, the ones that require the most careful testing and improvement are biomedical applications. The biocompatibility and antibacterial issues of medical devices remain a concern, as several prostheses still fail after several years of implantation and biofilm formation remains a real risk to the success of a device. Sputtered deposition prevents the introduction of hazardous chemical elements during the preparation of coatings, and this technique is environmentally friendly. In addition, the mechanical properties of C-based coatings are remarkable. In this paper, the latest advances in sputtering methods and biocompatibility and antibacterial action for diamond-based carbon (DLC)-based coatings are reviewed and the greater outlook is then discussed.This research is sponsored by national funds through FCT—Fundação para a Ciência e a Tecnologia, under the projects UIDB/00285/2020, UID/EMS/00285/2019 and UIDB/04650/2020, ATRITO-0 (co-financed via FEDER (PT2020) POCI-01-545 0145-FEDER-030446) and On-SURF (cofinanced via FEDER (PT2020) POCI-01-0247-FEDER-024521). Also, this work is supported by European Regional Development Fund (ERDF), through the Centro 2020 Regional Operational Programme under project CENTRO-01-0145-FEDER-000012-HealthyAging2020, and through the COMPETE 2020—Operational Programme for Competitiveness and Internationalization and Portuguese national funds via FCT-Fundação para a Ciência e a Tecnologia, under projects POCI-01-0145-FEDER-007440 and UID/NEU/04539/2019

RepositóriUM: implementação do DSpace em português: lições para o futuro e linhas de investigação.

Neste trabalho descrevemos a implementação do Repositório Institucional (RepositóriUM) da Universidade do Minho (UMinho), Portugal. A UMinho traduziu e está a utilizar a primeira versão em língua portuguesa do DSpace, um programa Open Source desenvolvido numa parceria entre o Massachusetts Institute of Technology (MIT) e a Hewlett-Packard (HP). As cinco fases definidas para o plano de implementação são descritas neste trabalho (1. instalação, tradução e configuração; 2. carregamento de teses e dissertações; 3. instituição das comunidades piloto; 4. abertura do repositório ao público, e 5. abertura para toda comunidade da UMinho), bem como as razões que conduziram à escolha das seis comunidades piloto de diferentes áreas do conhecimento para participarem nesse período de implementação (Sistemas de Informações; Engenharia de Polímeros; Engenharia Biológica; Gestão, e uma da área de Ciências Humanas e outra da área de Ciências Sociais). Neste artigo pretendemos compartilhar as lições aprendidas com o processo, e os caminhos de investigação que o projecto abriu, em particular para investigação e comparação de comportamentos de comunidades com diferentes culturas, de acordo com algumas questões e observações surgidas durante os primeiros dez meses de experiência. Tendo estas informações como base, foram identificados alguns caminhos para pesquisa que começam a ser desenvolvidos no contexto de pesquisas de mestrado ou doutorado na UMinho