1,655 research outputs found

    Optical Properties of Strained Graphene

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    The optical conductivity of graphene strained uniaxially is studied within the Kubo-Greenwood formalism. Focusing on inter-band absorption, we analyze and quantify the breakdown of universal transparency in the visible region of the spectrum, and analytically characterize the transparency as a function of strain and polarization. Measuring transmittance as a function of incident polarization directly reflects the magnitude and direction of strain. Moreover, direction-dependent selection rules permit identification of the lattice orientation by monitoring the van-Hove transitions. These photoelastic effects in graphene can be explored towards atomically thin, broadband optical elements

    Rejuvenescimento do cajueiro por meio de podas e substituição de copas.

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    Este trabalho teve como objetivo informar aos produtores de caju sobre as tecnologias para melhoria da cajucultura, tais como, rejuvenescimento de cajueiros antigos, substituição de copas por meio da eliminação seletiva de plantas...bitstream/item/80682/1/circular-44.PD

    Transformer-based language models for semantic search and mobile applications retrieval

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    Search engines are being extensively used by Mobile App Stores, where millions of users world-wide use them every day. However, some stores still resort to simple lexical-based search engines, despite the recent advances in Machine Learning, Information Retrieval, and Natural Language Processing, which allow for richer semantic strategies. This work proposes an approach for semantic search of mobile applications that relies on transformer-based language models, fine-tuned with the existing textual information about known mobile applications. Our approach relies solely on the application name and on the unstructured textual information contained in its description. A dataset of about 500 thousand mobile apps was extended in the scope of this work with a test set, and all the available textual data was used to fine-tune our neural language models. We have evaluated our models using a public dataset that includes information about 43 thousand applications, and 56 manually annotated non- exact queries. The results show that our model surpasses the performance of all the other retrieval strategies reported in the literature. Tests with users have confirmed the performance of our semantic search approach, when compared with an existing deployed solution.info:eu-repo/semantics/acceptedVersio

    Potencial de armazenamento de sementes de soja transgênica X convencional.

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    A soja Roundup Ready (RR) foi a primeira planta transgênica a ser aprovada para alimentação humana e animal para cultivo no Brasil. No caso da soja resistente ao glyphosate, a tolerância ao herbicida foi obtida pela inserção de um gene oriundo do genoma da Agrobacterium sp. Sob tratamento com esse herbicida, as plantas de soja não são afetadas, em virtude da ação continuada e sistemática dessa enzima alternativa, insensível ao produto. Porém, há relatos de decréscimo no potencial de armazenamento de sementes de soja transgênica, quando comparadas às convencionais. Neste trabalho o objetivo foi avaliar o potencial de armazenamento de sementes de variedades de soja transgênica (RR), comparativo a suas isolinhas não geneticamente modificadas. O potencial fisiológico (germinação e vigor - envelhecimento acelerado e emergência em areia) das variedades transgênicas foi analisado comparativamente com suas isolinhas em quatro períodos de armazenamento, com quatro repetições cada teste. As avaliações foram realizadas a cada dois meses. As variedades testadas foram BRS Valiosa RR e sua isolinha BR 46 Conquista; BRS 255 RR e BRS 137; BRS 245 RR e BRS 133. As variedades foram semeadas na mesma época e local, com o mesmo manejo cultural. Foi realizada capina manual, a colheita foi realizada em R7 e as plantas foram colocadas para secar a sombra. Após secas as vagens foram debulhadas manualmente. As sementes foram armazenadas em câmara refrigerada à temperatura de 18 ºC ± 2 ºC e 75% ± 4% de umidade relativa, até o momento da instalação dos experimentos. Não ocorreram variações nos potenciais de armazenamento entre as variedades transgênicas e suas isolinhas não geneticamente modificadas. O decréscimo do potencial fisiológico das sementes durante o armazenamento foi em função do qualidade inicial independente da variedade

    The SASSCAL contribution to climate observation, climate data management and data rescue in Southern Africa

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    A major task of the newly established "Southern African Science Service Centre for Climate Change and Adaptive Land Management" (SASSCAL; www.sasscal.org) and its partners is to provide science-based environmental information and knowledge which includes the provision of consistent and reliable climate data for Southern Africa. Hence, SASSCAL, in close cooperation with the national weather authorities of Angola, Botswana, Germany and Zambia as well as partner institutions in Namibia and South Africa, supports the extension of the regional meteorological observation network and the improvement of the climate archives at national level. With the ongoing rehabilitation of existing weather stations and the new installation of fully automated weather stations (AWS), altogether 105 AWS currently provide a set of climate variables at 15, 30 and 60 min intervals respectively. These records are made available through the SASSCAL WeatherNet, an online platform providing near-real time data as well as various statistics and graphics, all in open access. This effort is complemented by the harmonization and improvement of climate data management concepts at the national weather authorities, capacity building activities and an extension of the data bases with historical climate data which are still available from different sources. These activities are performed through cooperation between regional and German institutions and will provide important information for climate service related activities
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