69 research outputs found

    Esquemas de cooperação entre estações base para o LTE no sentido descendente

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    The explosive growth in wireless traffic and in the number of connected devices as smart phones or computers, are causing a dramatic increase in the levels of interference, which significantly degrades the capacity gains promised by the point-to-point multi input, multi output (MIMO) based techniques. Therefore, it is becoming increasingly clear that major new improvements in spectral efficiency of wireless networks will have to entail addressing intercell interference. So, there is a need for a new cellular architecture that can take these factors under consideration. It is in this context that LTE-Advanced arises. One of the most promising LTE-Advanced technology is Coordinated Multipoint (CoMP), which allows base stations to cooperate among them, in order to mitigate or eliminate the intercell interference and, by doing so, increase the system’s capacity. This thesis intends to study this concept, implementing some schemes that fall under the CoMP concept. In this thesis we consider a distributed precoded multicell approach, where the precoders are computed locally at each BS to mitigate the intercell interference. Two precoder are considered: distributed zero forcing (DZF) and distributed virtual signal-to-interference noise ratio (DVSINR) recently proposed. Then the system is further optimized by computing a power allocation algorithm over the subcarriers that minimizes the average bit error rate (BER). The considered algorithms are also evaluated under imperfect channel state information. A quantized version of the CSI associated to the different links between the BS and the UT is feedback from the UT to the BS. This information is then employed by the different BSs to perform the precoding design. A new DVSINR precoder explicitly designed under imperfect CSI is proposed. The proposed schemes were implemented considering the LTE specifications, and the results show that the considered precoders are efficiently to remove the interference even under imperfect CSI.O crescimento exponencial no tráfego de comunicações sem-fios e no número de dispositivos utilizados (smart phones, computadores portáteis, etc.) está a causar um aumento significativo nos níveis de interferência, que prejudicam significativamente os ganhos de capacidade assegurados pelas tecnologias baseadas em ligações ponto-a-ponto MIMO. Deste modo, torna-se cada vez mais necessário que os grandes aperfeiçoamentos na eficiência espectral de sistemas de comunicações sem-fios tenham em consideração a interferência entre células. De forma a tomar em consideração estes aspectos, uma nova arquitectura celular terá de ser desenvolvida. É assim, neste contexto, que surge o LTE-Advanced. Uma das tecnologias mais promissoras do LTE-Advanced é a Coordenação Multi-Ponto (CoMP), que permite que as estações base cooperem de modo a mitigar a interferência entre células e, deste modo, aumentar a capacidade do sistema. Esta dissertação pretende estudar este conceito, implementando para isso algumas técnicas que se enquadram no conceito do CoMP. Nesta dissertação iremos considerar a implementação de um sistema de pré-codificação em múltiplas células, em que os pré-codificadores são calculados em cada BS, de modo a mitigar a interferência entre células. São considerados dois pré-codificadores: Distributed Zero Forcing (DZF) e Distributed Virtual Signal-to-Interferance Noise Ratio (DVSINR), recentemente proposto. De seguida o sistema é optimizado com a introdução de algoritmos de alocação de potência entre as sub-portadoras com o objectivo de minimizar a taxa média de erros (BER). Os algoritmos considerados são também avaliados em situações em que a informação do estado do canal é imperfeita. Uma versão quantizada da CSI associada a cada uma das diferentes ligações entre as BS e os UT é assim enviada do UT para a BS. Esta informação é então utilizada para calcular os diferentes pré-codificadores em cada BS. Uma nova versão do pré-codificador DVSINR é proposta de modo a lidar com CSI imperfeito. Os esquemas propostos foram implementados considerandos especificações do LTE, e os resultados obtidos demonstram que os pré-codificadores removem de uma forma eficiente a interferência, mesmo em situações em que a CSI é imperfeita

    Mobilidade do sulfentrazone no perfil de classes de solos

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    The objective of this study was to determine the mobility of sulfentrazone in two soils classes as a function of increasing rain indices, as well as possible influences of the chemical and physical properties of soils with different iron oxides contents, on the herbicide action. The containers were 36 PVC tubes (10 cm diameter X 50 cm long). The containers were filled with soils and irrigated in 65%(w/w) and, then, the application of sulfentrazone (800g a.i/ha) was done on the exposed area. Subsequently, daily rainfalls of 10mm were simulated and, as the desired rain indices were reached (30, 60 and 90mm), six PVC tubes from each soil (with and without application) were disassembled. Five sorghum (Sorghum bicolor) seeds were sowing on soil from the depths 2,5-7,5-12,5-17,5-22,5-30,0 cm, and were maintained in a greenhouse for 15 days to evaluation of the germination and initial growth. After this time, an evaluation of possible morphophysiological changes that could be characterized as toxic effects of the product was done and the length of the shoot up to the last visible ligule. After measurement the shoots were dried in a forced draught over (70°C for 96h) to determine the dry matter. The results indicated that on the Dusky Red Latosol (Typic Acrustox) the product was percolated down to 12,5 cm with 90mm rainfall and on the Yellowish Red Latosol (Typic Acrustox) the sulfentrazone had little mobility, staying on the top 7,5cm, independently the rainfall.O trabalho objetivou determinar a mobilidade do sulfentrazone em duas classes de solos em função de índices pluviométricos crescentes, bem como possíveis influências das propriedades químicas e físicas de solos com diferentes teores de ferro na ação do herbicida. Foram utilizados como recipientes 36 tubos de PVC de 10cm de diâmetro por 50cm de comprimento. Os recipientes foram preenchidos com os solos e umedecidos a 65% (p/p) da capacidade de saturação, quando fez-se a aplicação do sulfentrazone (800g i.a/ha) na área exposta dos solos. Na seqüência, foram simuladas chuvas diárias de 10mm e, ao atingir-se o índice pluviométrico desejado (30, 60 e 90mm), foram desmontados seis tubos de cada solo (com e sem aplicação). Foram semeadas cinco sementes de sorgo (Sorghum bicolor) nas profundidades de 2,5-7,5-12,5-17,5-22,5-30,0cm, que assim foram mantidas em casa de vegetação por 15 dias para avaliação da germinação e crescimento inicial. Decorrido esse tempo, foi realizada uma avaliação de possíveis alterações morfofisiológicas que pudesse ser caracterizada como efeitos tóxicos do produto e mediu-se o comprimento da parte aérea até a última lígula visível. As partes aéreas foram secas em estufa com circulação forçada de ar (70°C por 96h) para obtenção de matéria seca. Pelos resultados obtidos, verificou-se que no Latossolo Vermelho distroférrico o produto foi até os 12,5 cm com 90mm de precipitação e no Latossolo Vermelho – Amarelo o sulfentrazone foi pouco móvel, permanecendo nos 7,5cm superficiais, independentemente da precipitação

    Biological activities and physicochemical characterization of alkaline lignins obtained from branches and leaves of Buchenavia viridiflora with potential pharmaceutical and biomedical applications

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    Funding Information: The study was funded by Foundation for the State of Pernambuco (Process - FACE-04.03/19 ), AP Researcher Research Grant - FACEPE (Process BFP-0038-0 ) and National Council for Scientific and Technological Development grant - CNPq (Process 306865/2020-3 ). This research was also funded by the Foundation for Science and Technology (FCT) through the GHTM ( UID/04413/2020 ). Thanks to MR4, who provided us with the Plasmodium falciparum strains that we used in the assays. We also thank the Laboratory of Magnetic Resonance of the Institute of Chemistry and Biotechnology (Federal University of Alagoas- UFAL) for the analysis of NMR. In addition to these, we would also like to thank Mil Madeiras Preciosas, a subsidiary of the Swiss group Precious Woods ( http://preciouswoods.com.br/ ) for providing samples of branches and leaves of Buchenavia viridiflora. Publisher Copyright: © 2022In this work, we investigated in vitro different biological activities of alkaline lignins extracted from the species Buchenavia viridiflora, a tree from the Amazon rainforest used as a wood product. The chemical composition results for the twig and leaves were, respectively (%): cellulose (30.88 and 24. 28), hemicellulose (21.62 and 23.03), lignin (29.93 and 25.46), extractives (13.06 and 20.52), and ash (4.51 and 6.72). The yield was higher for the lignin of the branches (67.9 %) when compared to the leaves (60.2 %). Lignins are of the GSH type, low molecular weight and thermally stable. They promoted moderate to low antioxidant activity, highlighting the lignin of the branches, which presented an IC50 of 884.56 μg/mL for the DPPH assay and an IC50 of 14.08 μg/mL for ABTS. In the cytotoxicity assays, they showed low toxicity against macrophage cells (IC50 28.47 and 22.58 μg/mL). In addition, they were not cytotoxic against splenocytes and erythrocytes at concentrations ranging from 100 to 6.25 μg/mL. These were able to promote splenocyte proliferation and induce the production of anti-inflammatory cytokines. And inhibit the growth of tumor cells with IC50 ranging from 12.63 to values >100 μg/mL and microbial at a concentration of 512 μg/mL. Finally, they showed antiparasitic activity by inhibiting the growth of chloroquine-sensitive and resistant Plasmodium falciparum strains. These findings reinforce that the lignins in this study are promising for potential pharmaceutical and biomedical applications.publishersversionpublishe

    Cenários para a matriz de geração de eletricidade do Ceará em 2050: pt

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    Based on the worldwide proposition of energy matrix scenarios for 2050, the objective of this article is to present scenarios of electricity generation for Ceará in 2050, showing the participation of sources already used in the state's electric matrix and adding new ones. The article proposes three scenarios: a conservative one, where the present proportion of electricity generation sources of the state is maintained, a transitional one, with 50% of electricity generation from non-renewable sources and the other 50% from renewable sources, and 100% renewable, without the use of fossil or nuclear fuels. Estimates for 2050 in the state are obtained by extrapolating generation data from 2011 to 2017, reaching an estimated 94,775 GWh. In the conservative scenario, it is observed that half of this generation is made by thermoelectric plants and the other half by wind farms. In the transition scenario, dominated by the use of natural gas, the exponential growth of photovoltaic generation stands out. In the 100% renewable scenario, dominated by wind farms, in addition to the similar growth of photovoltaic generation as in the transition scenario, we highlight the use of urban solid waste and solar thermal concentration plants.A partir da proposição de cenários de matrizes energéticas a nível mundial para 2050, o objetivo do presente artigo é apresentar cenários de geração de eletricidade para o estado do Ceará em 2050, mostrando a participação de fontes já usadas na matriz elétrica do estado e acrescentando novas. O artigo propõe três cenários: um conservador, onde é mantida a proporção atual das fontes de geração de eletricidade do estado, um de transição, com 50% da geração de energia elétrica oriunda de fontes não renováveis e os outros 50% provenientes de fontes renováveis, e um 100% renovável, sem o uso de combustíveis fósseis ou nuclear. As estimativas para 2050 no estado são obtidas através de extrapolação de dados de geração de 2011 a 2017, alcançando um valor estimado de 94.775 GWh. No cenário conservador, observa-se que metade dessa geração é realizada por termelétricas e a outra metade por parques eólicos. No cenário de transição, dominado pelo gás natural, destaca-se o crescimento exponencial da geração fotovoltaica. No cenário 100% renovável, dominado por parques eólicos, além do crescimento semelhante da geração fotovoltaica como no cenário de transição, destaca-se a utilização dos resíduos sólidos urbanos e de centrais solar térmicas de concentração

    MAMMALS IN PORTUGAL : A data set of terrestrial, volant, and marine mammal occurrences in P ortugal

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    Mammals are threatened worldwide, with 26% of all species being includedin the IUCN threatened categories. This overall pattern is primarily associatedwith habitat loss or degradation, and human persecution for terrestrial mam-mals, and pollution, open net fishing, climate change, and prey depletion formarine mammals. Mammals play a key role in maintaining ecosystems func-tionality and resilience, and therefore information on their distribution is cru-cial to delineate and support conservation actions. MAMMALS INPORTUGAL is a publicly available data set compiling unpublishedgeoreferenced occurrence records of 92 terrestrial, volant, and marine mam-mals in mainland Portugal and archipelagos of the Azores and Madeira thatincludes 105,026 data entries between 1873 and 2021 (72% of the data occur-ring in 2000 and 2021). The methods used to collect the data were: live obser-vations/captures (43%), sign surveys (35%), camera trapping (16%),bioacoustics surveys (4%) and radiotracking, and inquiries that represent lessthan 1% of the records. The data set includes 13 types of records: (1) burrowsjsoil moundsjtunnel, (2) capture, (3) colony, (4) dead animaljhairjskullsjjaws, (5) genetic confirmation, (6) inquiries, (7) observation of live animal (8),observation in shelters, (9) photo trappingjvideo, (10) predators dietjpelletsjpine cones/nuts, (11) scatjtrackjditch, (12) telemetry and (13) vocalizationjecholocation. The spatial uncertainty of most records ranges between 0 and100 m (76%). Rodentia (n=31,573) has the highest number of records followedby Chiroptera (n=18,857), Carnivora (n=18,594), Lagomorpha (n=17,496),Cetartiodactyla (n=11,568) and Eulipotyphla (n=7008). The data setincludes records of species classified by the IUCN as threatened(e.g.,Oryctolagus cuniculus[n=12,159],Monachus monachus[n=1,512],andLynx pardinus[n=197]). We believe that this data set may stimulate thepublication of other European countries data sets that would certainly contrib-ute to ecology and conservation-related research, and therefore assisting onthe development of more accurate and tailored conservation managementstrategies for each species. There are no copyright restrictions; please cite thisdata paper when the data are used in publications.info:eu-repo/semantics/publishedVersio

    Pervasive gaps in Amazonian ecological research

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    Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

    Pervasive gaps in Amazonian ecological research

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    Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

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    The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016
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