Experimental Realization of the Fuse Model of Crack Formation

In this work, we present an experimental investigation of the fuse model. Our main goal was to study the influence of the disorder on the fracture process. The experimental apparatus used consisted of an $L\times L$ square lattice with fuses placed on each bond of the lattice. Two types of materials were used as fuses: copper and steel wool wires. The lattice composed only by copper wires varied from a weakly disordered system to a strongly disordered one. The lattice formed only by steel wool wires corresponded to a strongly disordered one. The experimental procedure consisted of applying a potential difference V to the lattice and measuring the respective current I. The characteristic function $I(V)$ obtained was investigated in order to find the scaling law dependence of the voltage and the current on the system size $L$ when the disorder was changed. Our results show that the scaling laws are only verified for the disordered regime.Comment: 4 pages, 8 figures.ep

Investigating natural acidified marine environments

Jornadas "Ciência nos Açores – que futuro?", Ponta Delgada, 7-8 de Junho de 2013.As fontes hidrotermais de superfície constituem laboratórios naturais para investigar ambientes marinhos naturalmente acidificados como modelos para a avaliação dos efeitos da acidificação dos oceanos. Os organismos nestas zonas estão sujeitos às condições acídicas, bem como às variações de temperatura e exposição a produtos químicos, incluindo a libertação de metais pesados. Ambientes extremos podem promover alterações nas comunidades, organismos ou processos fisiológicos. Algumas das estratégias, mecanismos, adaptações ou até mesmo especiação (novas espécies) poderiam mostrar como viver nesses ambientes e ajudar a descobrir organismos suficientemente sensíveis para atuar como sentinelas (bioindicadores) e, eventualmente adaptações biológicas associadas com potencial uso biotecnológico. Algumas espécies, devido à sua estrutura calcária (sensíveis a condições ácidas) requerem uma atenção especial. As fontes hidrotermais de superfície são uma característica peculiar dos Açores. Representam ambientes únicos e constituem patrimônio natural do litoral dos Açores. No presente projeto pretende-se investigar os efeitos da atividade hidrotermal em comunidades subtidais macrobentónicas em São Miguel, com uma abordagem inovadora no estudo dos efeitos da acidificação dos oceanos. A comparação entre locais com atividade hidrotermal e locais sem atividade hidrotermal irá fornecer informações sobre as diferenças na distribuição das espécies. Esta informação será complementada com a investigação sobre as respostas de organismos selecionados aos efeitos de viver sob a influência das fontes hidrotermais.ABSTRACT: Shallow water hydrothermal vents constitute natural laboratories to investigate natural acidified marine environments as models for the evaluation of the effects of ocean acidification. Organisms at those areas are subject to acidic conditions, as well as to temperature variations and exposure to chemicals, including the release of heavy metals. The extreme environment can promote changes on the communities, organisms or physiological processes. Some of the strategies, mechanisms, adaptations or even speciation (new species) could show how to live in these environments and help discovering organisms sufficiently sensitive to act as early sentinels (bioindicators) and possible associated biological adaptations with potential biotechnological use. Some species, due to their calcareous structure (sensitive to acidic conditions) need special attention. Shallow water hydrothermal vents are striking features of the Azores. They represent unique environments and constitute a natural patrimony of the Azorean coastline. In the present project we investigate the effects of hydrothermal activity on subtidal macrobenthic communities in the island of São Miguel, in an innovative approach to study ocean acidification effects. A comparison between sites with hydrothermal activity and sites without hydrothermal activity will provide information on species distribution differences. This information will be complemented with research on the responses of selected organisms to the effects of living under the vents influence

Modificações na concha de lapas em fontes hidrotermais de superfície

Copyright © 2012 APRH.Os organismos calcários são conhecidos por serem sensíveis à água do mar acidificada, e têm sido apontados como potenciais sentinelas para estudos sobre acidificação do oceano. As lapas estão entre os organismos que caracterizam a zona intertidal e nos Açores, podendo também ser encontradas em locais com actividade hidrotermal de superfície, onde a acidez da água do mar na proximidade das fontes hidrotermais é naturalmente mais elevada devido à liberação de CO2. Durante uma visita ocasional para avaliar a ocorrência e abundância de algas no intertidal encontraram-se vários espécimes de Patella candei gomesii (Patellidae) com conchas aberrantes, na proximidade de fontes hidrotermais. Estes indivíduos, colectados sob tais condições exibiam conchas frágeis, quase transparentes, com espessura muito reduzida.ABSTRACT: Calcareous organisms are known to be sensitive to acidified seawater, and they have been reported as potential sentinels for ocean acidification studies. Limpets are among the organisms that characterise intertidal zones, and in the Azores can also be found at sites with shallow water hydrothermal activity, where the acidity of seawater in the vicinity of hydrothermal vents is naturally higher due to CO2 release. During an occasional intertidal survey on the occurrence and abundance of intertidal algae we found limpets with abnormal shells, and specimens of Patella candei gomesii (Patellidae) collected under such conditions exhibited weak and almost transparent shells with reduced shell thickness

Some elements concentrations of Corallina elongata from São Miguel (Azores) under different environmental conditions.

43rd European Marine Biology Symposium. Ponta Delgada, Açores, 8-12 de Setembro de 2008

Free androgens and progestins and their conjugated forms in serum and urine of stellate sturgeon (Acipenser stellatus Pallas) males

Stellate sturgeon (Acipenser stellatus Pallas) males from Volga River treated with LH-RH-A showed an increase of free, sulfated and glucuronided sex steroid levels in serum and urine at spermiation. Conjugated forms of sex steroids could act as pheromones in sturgeon

Levels of free and conjugated androgens and progestins in coelomic fluid and serum of stellate sturgeon (Acipenser stellatus Pallas) females

Stellate sturgeon (Acipenser stellatus Pallas) females from the Volga River were analysed for sex steroids after hormonal stimulation. The results show a significant increase of sulfated sex steroid levels in serum and coelomic fluid (CF) at final maturation (FM). It is hypothesized that the steroid metabolites could be part of a chemical communication system related to reproduction

Differences in the Prevalence of Non-Communicable Disease between Slum Dwellers and the General Population in a Large Urban Area in Brazil.

Residents of urban slums are at greater risk for disease than their non-slum dwelling urban counterparts. We sought to contrast the prevalences of selected non-communicable diseases (NCDs) between Brazilian adults living in a slum and the general population of the same city, by comparing the age and sex-standardized prevalences of selected NCDs from a 2010 survey in Pau da Lima, Salvador Brazil, with a 2010 national population-based telephone survey. NCD prevalences in both populations were similar for hypertension (23.6% (95% CI 20.9⁻26.4) and 22.9% (21.2⁻24.6), respectively) and for dyslipidemia (22.7% (19.8⁻25.5) and 21.5% (19.7⁻23.4)). Slum residents had higher prevalences of diabetes mellitus (10.1% (7.9⁻12.3)) and of overweight/obesity (46.5% (43.1⁻49.9)), compared to 5.2% (4.2⁻6.1) and 40.6% (38.5⁻42.8) of the general population in Salvador. Fourteen percent (14.5% (12.1⁻17.0)) of slum residents smoked cigarettes compared to 8.3% (7.1⁻9.5) of the general population in Salvador. The national telephone survey underestimated the prevalence of diabetes mellitus, overweight/obesity, and smoking in the slum population, likely in part due to differential sampling inside and outside of slums. Further research and targeted policies are needed to mitigate these inequalities, which could have significant economic and social impacts on slum residents and their communities

Contribuição para o conhecimento biológico das águas interiores da Graciosa

XI Expedição Científica do Departamento de Biologia - Graciosa 2004.Das três pequenas lagoas permanentes existentes na ilha até meados do século passado, duas desapareceram e a terceira está completamente artificializada. Neste momento as zonas húmidas dulçaquícolas naturais da ilha Graciosa reduzem-se a dois pequenos charcos (Barreiro e Tanque), ambos fortemente eutrofizados. São apresentadas listas das espécies de algas, plantas vasculares, invertebrados bênticos e vertebrados aí encontrados

New additions to the Azorean algal flora with ecological observations on rhodolith formations.

43rd European Marine Biology Symposium”. Ponta Delgada, Açores, 8-12 de Setembro de 2008

Abiotic modulation of Spartina maritima photobiology in different latitudinal populations

Spartina maritima has a very wide distribution in the northern hemisphere salt marshes crossing a wide variety of climatic environments. Therefore, it is not strange that some differences arise when observing the photosynthetic mechanisms of different populations inhabiting different latitudes. During this study it could be observed that climate is the most important factor controlling the photosynthetic traits of different populations distributed along a climatic gradient, namely the air temperature, humidity and light environment. Also some sediment physicochemical parameters such as pH and pore water salinity showed important influences driving the photosynthetic mechanisms in S. maritima. Furthermore S. maritima is one of the most abundant halophytes colonizing the Portuguese salt marshes. These facts have greater importance if one considers the large abundance of this halophytic species and how climate change will affect their metabolism and thus the ecosystem services provided by this species to the estuarine system.The authors would like to thank to the “ Fundação para a Ciência e Tecnologia (FCT)” for funding the research in the Centre of Oceanography throughout the project PEst-OE/MAR/UI0199/2011 and this specific work throughout the projects ECOSAM (PTDC/ AAC-CLI/104085/2008) and 3M RECITAL (LTER/BIA-BEC/0019/ 2009). B. Duarte investigation was supported by FCT throughout a PhD grant (SFRH/BD/75951/2011)