The Nonlinear Optical Effects of Opening a Gap in Graphene

Graphene possesses remarkable electronic, optical and mechanical properties that have taken the research of two-dimensional relativistic condensed matter systems to prolific levels. However, the understanding of how its nonlinear optical properties are affected by relativistic-like effects has been broadly uncharted. It has been recently shown that highly-nontrivial currents can be generated in free-standing samples, notably leading to the generation of even harmonics. Since graphene monolayers are centrosymmetric media, for which such harmonic generation is deemed inaccessible, this light-driven phenomenon is both startling and promising. More realistically, graphene samples are often deposited on a dielectric substrate, leading to additional intricate interactions. Here, we present a treatment to study this instance by gapping the spectrum and we show this leads to the appearance of a Berry phase in the carrier dynamics. We analyse the role of such a phase in the generated nonlinear current and conclude that it suppresses odd-harmonic generation. The pump energy can be tuned to the energy gap to yield interference among odd harmonics mediated by interband transitions, allowing even harmonics to be generated. Our results and general methodology pave the way for understanding the role of gap-opening physical factors in the nonlinear optics of hexagonal two-dimensional lattices.Comment: 5 figure

Recreational harvesting of the wedge clam (Donax trunculus) in southern Portugal: characterization of the activity based on harvesters’ perception and local ecological knowledge

This study was the first attempt to characterize the recreational harvesting of the wedge clam (Donax trunculus). For this purpose, 403 face-to-face interviews were performed in the summers of 2018 and 2019 in southern Portugal. The majority of the harvesters frequented the selected beaches during holidays and collected wedge clams as a hobby for an appetizer. The respondents reported an inter-annual variation in their catches of wedge clam with a decreasing abundance in 2018 followed by a recovery in 2019, but with more recreational harvesters collecting undersized individuals. Although most harvesters declared to consume D. trunculus, only a few bought wedge clams being the clams' size a secondary factor in their valorization. The majority of the recreational harvesters did not know the species' minimum conservation reference size nor the legally allowed maximum daily catch. It was estimated that recreational harvesters can collect 13 tonnes of wedge clams during the summer season along the southeastern coast of Algarve. Even though manual harvesting is not an efficient fishing technique, the lack of selectivity of harvesters can eventually compromise the resilience of D. trunculus populations. Despite most respondents affirmed to get informed about marine biotoxins, most surveys were done during periods of interdiction for shellfish harvesting. The present results revealed that the population is still unaware of the health risks of consuming shellfish contaminated with biotoxins. Educational activities and awareness campaigns are required to further inform recreational harvesters about the regulations in force for this activity and the sanitary threats of marine biotoxins.VENUS” Ref. 0139_VENUS_5_E. 2017–2019; VENUS ref. IPMA-2018-008-BI;info:eu-repo/semantics/publishedVersio

Tissue engineering and regenerative medicine research - how can it contribute to fight future pandemics?

Understanding the pathogenesis of viral infection is of paramount importance for the development of better therapies. In the particular case of COVID-19, the mechanism of infection is highly complex and involves a critical cascade of events, which can lead to the death of the patient. Intense research is currently being performed to gain mechanistic insights about the virus etiology and to evaluate new therapeutic approaches. The development of point-of-care diagnostic tools, predictive drug screening platforms, and biomimetic models of the disease could play a key role in understanding the cellular and molecular mechanism of viral infection and its response to drugs. In this regard, specific tissue engineering and regenerative medicine approaches, such as microfluidics and organ-on-a-chip technologies, as well as bioprinted in vitro disease models, could be used to develop a technological platform to fight COVID-19, and other virus pandemics yet to come. Herein, we briefly discuss about how such approaches can contribute to address current and future viral pandemics by highlighting recent successful examples.D. Caballero acknowledges the financial support from the Portuguese Foundation for Science and Technology under the program CEEC Individual 2017 (CEECIND/00352/2017) and the project 2MATCH (02/SAICT/2017 - nº 028070) funded by the Programa Operacional Regional do Norte supported by FEDER. M. Carvalho would like to acknowledge IET Harvey Research Prize 2017. The authors also acknowledge the financial support from the EU Framework Programme for Research and Innovation Horizon 2020 on Forefront Research in 3D Disease Cancer Models as in vitro Screening Technologies (FoReCaST- no. 668983), the Portuguese Foundation for Science and Technology (FCT) distinction attributed to J. M. Oliveira (IF/00423/2012, IF/01285/2015) and FCT, Fundo Europeu de Desenvolvimento Regional (FEDER) and Programa Operacional Competitividade e Internacionalização (POCI) for funding the projects B-Liver (PTDC/EMD-EMD/29139/2017), Hierarchitech (M-ERA-NET/0001/2014) and 3BioMeD (JICAM/0001/2017)

Ecological resilience in lakes and the conjunction fallacy

There is a pressing need to apply stability and resilience theory to environmental management to restore degraded ecosystems effectively and to mitigate the effects of impending environmental change. Lakes represent excellent model case studies in this respect and have been used widely to demonstrate theories of ecological stability and resilience that are needed to underpin preventative management approaches. However, we argue that this approach is not yet fully developed because the pursuit of empirical evidence to underpin such theoretically grounded management continues in the absence of an objective probability framework. This has blurred the lines between intuitive logic (based on the elementary principles of probability) and extensional logic (based on assumption and belief) in this field

Monitorização dos problemas fitossanitários e fauna auxiliar presentes em pomares de macieiras da ilha Terceira

I Congresso de Fruticultura e Viticultura. Angra do Heroísmo 17-19 Abril 2008.Trabalho de investigação desenvolvido no projecto INTERFRUTA II, financiado pelo programa INTERREG III-B (05/MAC/3.1/A4).Nos objectivos do Projecto INTERFRUTA II, projecto desenvolvido nas Ilhas da Madeira, Tenerife (Canárias) e Terceira (Açores) destinado a contribuir para a promoção da fruticultura e viticultura nestas três regiões insulares, procurou-se atingir uma melhoria dos conhecimentos sobre diversas culturas abrangidas nos diversos trabalhos de investigação e de entre as quais a das macieiras, onde através deste trabalho, nas duas zonas de maior produtividade da Ilha Terceira (Biscoitos e São Sebastião), se procurou conhecer os seus problemas fitossanitários, de forma a determinar os períodos de maior actividade e risco principalmente das pragas que afectam a macieira e assim tentar encontrar a melhor forma de as poder combater através da aplicação prática dos conceitos da Protecção Integrada, o que contribuiu, decisivamente, para o conhecimento e procura de soluções inovadoras que conduziram ao acréscimo do rendimento dos produtores e a uma menor utilização e aplicação de pesticidas. Para além disso, pretendeuse identificar toda a fauna auxiliar presente nos pomares de macieira estudados. Nas macieiras, os principais problemas fitossanitários decorrem da presença de aranhiço vermelho (Panonychus ulmi Koch), traça-oriental (Cydia molesta) e bichado (Cydia pomonella L.). Nos fungos foram encontrados Alternaria mali Roberts, Aspergillium sp., Botryosphaeria lutea, Botryosphaeria ribis Gross.& Dungar, Phoma glomerata (Corda) Wolll. Rhizoctonia solani Kuhn, Verticillium sp. Nos vírus o único encontrado nas folhas de macieira foi o ACLSV – Apple chlorotic leafspot vírus. Da totalidade dos espécimes da fauna auxiliar encontrados nos pomares de macieira estudados foi elaborada uma tabela

Structural properties of mixed conductor Ba1−xGd1−yLax+yCo2O6−δ

BaGdLaCoO (BGLC) compositions with large compositional ranges of Ba, Gd, and La have been characterised with respect to phase compositions, structure, and thermal and chemical expansion. The results show a system with large compositional flexibility, enabling tuning of functional properties and thermal and chemical expansion. We show anisotropic chemical expansion and detailed refinements of emerging phases as La is substituted for Ba and Gd. The dominating phase is the double perovskite structure Pmmm, which is A-site ordered along the c-axes and with O vacancy ordering along the b-axis in the Ln-layer. Phases emerging when substituting La for Ba are orthorhombic Ba-deficient Pbnm and cubic LaCoO-based R3̄c. When La is almost completely substituted for Gd, the material can be stabilised in Pmmm, or cubic Pm3̄m, depending on thermal and atmospheric history. We list thermal expansion coefficients for x = 0-0.3, y = 0.2.The research has been supported by the National Science Centre Poland (2016/22/Z/ST5/00691), the Spanish Ministry of Science and Innovation (PCIN-2017-125, RTI2018-102161 and IJCI-2017-34110), and the Research Council of Norway (Grant no. 272797 “GoPHy MiCO”) through the M-ERA.NET Joint Call 2016. The authors acknowledge the skilful assistance from the staff of the Swiss–Norwegian Beamline (SNBL) at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. Dr. Cheng Li at POWGEN, SNS, Oak Ridge, US and Dr. Chiu C. Tang at beamline I11 at Diamond, Didcot, UK are gratefully acknowledged for PND and SR-PXD measurements, respectively

O contributo do projecto INTERFRUTA II para o desenvolvimento da fruticultura na ilha Terceira, Açores

13º Congresso da APDR (Associação Portuguesa para o Desenvolvimento Rural). Angra do Heroísmo, Julho de 2007.O Projecto Interfruta II é um projecto apoiado pelo programa Interreg III-B, desenvolvido nas Ilhas da Madeira, Tenerife (Canárias) e Terceira (Açores) destinado a contribuir para a promoção da fruticultura e viticultura nestas três regiões insulares, procurando uma melhoria dos conhecimentos sobre os problemas fitossanitários que afectam as macieiras, bananeiras, castanheiros e a vinha, aplicando técnicas que contribuam decisivamente para o conhecimento e procura de soluções, numa vertente de prospecção das pragas-chave, fauna auxiliar, doenças e vírus que afectam essas culturas. Destaca-se o facto de inicialmente se ter procedido à realização de 160 inquéritos aos produtores e ao levantamento e identificação, através de SIG, das áreas de produção frutícola da Ilha. Para a análise dos factores climáticos ao nível da parcela, foram instaladas nas três zonas em estudo, estações meteorológicas de leitura automática.ABSTRACT: The INTERFRUTA project is financed by the European Commission Interreg III-B Programme and was developed for the islands of Madeira, Tenerife and Terceira for the improvement of fruit and vineyard production in these three Atlantic regions. The project goal is a better knowledge of the phytossanitary problems that affect apples, bananas, chestnut and vineyards, applying methods that will contribute to solutions based on the survey of key pests, diseases and beneficial organisms. All these work began with a survey to 160 producers and those data permitted, applying GIS techniques to them to identify the Terceira island fruit and vineyard production areas. To register the climate conditions in each area studied fully automatic meteorological stations were put in each of the three studied areas