Estudo da linha de irreversibilidade em supercondutores do tipo II

Orientador: Oscar Ferreira de LimaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica "Gleb Wataghin"Resumo: Apresenta-se neste trabalho um estudo da linha de irreversibilidade (L.I.) em amostras de supercondutores convencionais do tipo II de baixo k e uma amostra de YBa2Cu3O7-d texturizada por fusão (YMT), utilizando-se de curvas M vs. T obtidas com um magnetômetro-SQUID. Os supercondutores convencionais estudados foram esferas de Nb puro (k » 1.5) e pó de uma solução sólida de Nb com 1.55%at O (k » 6.5) prensado em formato cilíndrico (Nb-O). As L.I. das amostras de supercondutores convencionais foram muito bem ajustadas pela equação de fusão da rede de vórtices de Houghton e col., porém com constantes de Lindemann (cL) irrealisticamente pequenas, cL = 0.0036 para a amostra de Nb e cL = 0.026 para a amostra Nb-O. As L.I. destas amostras também foram muito bem ajustadas por uma lei de potências decorrente do modelo de "depinning" termicamente ativado da rede de vórtices. Neste modelo o expoente n da lei de potências também pode ser obtido a partir de medidas de corrente crítica Jc(B,T) feitas em baixas temperaturas. Obtivemos Jc(B,T) a partir de medidas de M vs. H usando o modelo de Bean, sendo que o expoente n obtido destas medidas concorda com o obtido do ajuste da L.I. dentro de 20% e 10% para as amostras de Nb e Nb-O respectivamente. Acreditamos que neste caso a melhor explicação para a origem da L.I. é o "depinning" termicamente ativado da rede de vórtices. A L.I. para a amostra de YMT foi obtida em 2 orientações diferentes e a equação de fusão da rede de vórtices com correções quânticas ajustou-se muito bem em ambos os casos. Neste ajuste, cL e v foram os únicos parâmetros livres. Os valores de Tc(H) foram obtidos para esta amostra a partir de uma lei e escala baseada na teoria de flutuações para sistemas 3D. O resultado deste ajuste é similar ao obtido por outros autores no estudo de monocristais sem macias, o que sugere que a fusão da rede de vórtices em altas temperaturas é pouco influenciada pelo aumento da desordem da redeAbstract: Not informedDoutoradoFísicaDoutor em Ciência

2D Modeling of HTS Coils with T-A Formulation: How to Handle Different Coupling Scenarios

Numerical models based on the finite-element method (FEM) are popular tools for investigating the macroscopic electromagnetic behavior of high-temperature superconductor (HTS) applications. This article explains how to use the T-A formulation for modeling HTS coils in 2D with different coupling scenarios between the turns. First we consider a racetrack coil wound from one piece of superconducting tape. Then we consider a coil obtained by winding a cable composed of different HTS tapes. In the latter case, the tape turns are either electrically connected along their entire length or just at the two ends of the coil: in the model, these two different types of electrical connection are implemented with the help of the electrical circuit module. The current density distributions and the AC losses of the coils in the different coupling scenarios are compared and discussed. The limits of applicability of the presented approach are pointed out. The model is developed for the straight section of racetrack coils, but can be easily adapted to axisymmetric geometries

Magnetic bearings with double crossed loops modelled with T-A formulation and electric circuits

The application of High-Temperature Superconductor (HTS) coils made of coated conductors has been investigated for many years. A possible configuration for such coils is the jointless loop, also known as the ring coil. The double crossed loop coil (DCLC) has been successfully applied in superconducting magnetic bearings (SMBs). The design of SMBs with DCLCs requires flexible modelling to allow all parts of the device to be represented. This work proposes the T-A formulation with a thin-film approximation for modelling SMB with DCLCs in the finite element analysis framework. A 2D representation of the system is coupled with an external electric circuit to model the continuity of the lines that represent the parts of each jointless loop. To couple the T-A formulation and the circuit, an average of the total electric field, with both resistive and inductive components, is applied to the circuit. The total current computed by the circuit is applied to the T-A formulation. The proposed methodology was validated by comparison with levitation force experimental data. Two types of tests were simulated: five levitation force tests and three guidance force tests. It is shown that there is a limit to the behaviour of the levitation force related to the high-loss state. Below this limit, the stack of DCLCs behaves as an equivalent bulk. Beyond this limit, a high-loss state appears as a linear growth of the levitation force. It is also shown that this high-loss state in vertical displacement influences the lateral force

The association of medroxyprogesterone to the Ovsynch protocol for the fixed time artificial insemination of cyclic buffaloes (Bubalus bubalis) in the Eastern Amazon

O presente estudo visou avaliar os efeitos da associação da medroxiprogesterona (análogo sintético da progesterona) ao protocolo Ovsynch sobre o crescimento folicular, a ovulação e a taxa de concepção de búfalas criadas na Amazônia Oriental (Tracuateua-PA). Vinte e sete fêmeas adultas (G1 n=14 e G2 n=13), cíclicas, sem bezerro ao pé e com ECC 3,5 foram submetidas a Ovsynch. Os animais do G2 receberam 60 mg de medroxiprogesterona entre D0 e D7 (D0=início do tratamento). A ultra-sonografia ovariana foi realizada nos D 0, 7, 9 e 10. O contingente de folículos pequenos diferiu no D7 (G1: 4,57±0,60 versus G2: 6,54±0,67; P=0,05). Tempo e tratamento influenciaram o diâmetro folicular no D7. O crescimento do folículo dominante entre D7 e D9 foi maior nos animais tratados (G1: 2,05±0,49 mm/dia versus 3,48±0,41 mm/dia; P<0,05). Mais animais do G1 ovularam precocemente (35,71% versus 30,77%), porém isso não afetou as taxas de concepção (G1: 50,00% e G2: 30,77%; P>0,05). Os achados sugerem que a medroxiprogesterona (1) aumenta recrutamento folicular e retarda o crescimento dos folículos com diâmetro maior que 5,0 mm entre D0 e D7; (2) sua retirada incrementa em 1,7 vezes o crescimento folicular do D7 ao D9; (3) pode contribuir para a ovulação de folículos maiores e, em tese, para maior formação de tecido luteínico; (4) não promove ovulação precoce após o Ovsynch; (5) não eleva as taxas de concepção após sincronização de fêmeas cíclicas e com bom escore corporal, devendo ser avaliada para uso em fêmeas acíclicas ou com ECC mais baixo.The aim of this study was to evaluate the effect of the association of medroxyprogesterone with the Ovsynch protocol on the follicular growth, ovulation, and conception rate of buffaloes in the Eastern Amazon (Tracuateua-PA). Twenty-seven cyclic, non-lactating females (G1 n=14 and G2 n=13) with a 3.5 BCS were synchronized with the Ovsynch. Animals from G2 received a supplementation of 60 mg of medroxyprogesterone from D0 to D7 (D0=starting day of treatment). Ultrasonography evaluation on ovaries was realized on Days 0, 7, 9, and 10. A significant effect of treatment on follicle number was observed on D7 (G1: 4.57±0.60 versus G2: 6.54±0.67; P=0.05). Time and treatment influenced follicular diameter on D7. The growth of the dominant follicular was increased from D7 to D9 on treated females (G1: 2.05±0.49 mm/day versus 3.48±0.41 mm/day; P<0.05). G1 animals (35.71% versus 30.77%) ovulated comparatively earlier than their G2 counterparts, but this did not affect the conception rates (G1: 50,00% and G2: 30,77%; P>0,05). The findings suggest that medroxyprogesterone: (1) increases follicular recruitment and inhibits the growth of follicles whose diameter was larger than 5.0mm from D0 to D7; (2) the withdrawal of medroxyprogesterone speeds up follicular growth 1.7 fold from D7 to D9; (3) would probably contribute to the ovulation of larger follicles thereby forming more luteal tissue; (4) does not stimulate early ovulation after Ovsynch; and (5) does not elevate the conception rate after the synchronization of cyclic females with good body condition, and should be evaluated for the utilization in acyclic/reduced BCS females.Embrapa Amazônia OrientalBanco da Amazôni

Margem de lucro proporcionada pela aplicação de um fertilizante NPK em diferentes níveis em cafeeiros irrigados

The lack of management preparation inherited down from past regulations interferes in economic results of production. During the productive cycles the quantity of fertilizers are effected without the technical recommendations, which may economically render the production. The product, therefore, demands information to act strategically on its own business. The main objective for this project was analyzed the profit margin provided by application of a fertilizer NPK at different levels in coffee plants irrigated. The analyses contemplated the harvests of 2012/2013 and 2013/2014 of an experiment carried out at the Federal University of Lavras (UFLA). The outlining was made in random blocks with six treatments and four repetitions, being six levels of fertilization with fertilizers containing N, P2O5 e K2O that were from 10, 40 ,70 ,100 ,130 and 160% of recommended standards for coffee producers of dry farming. There was a significant effect from the levels of fertilizers in effect in relation with the productivity on the biennium, and the maximum production was reached with the application of the fertilizer on the level of 145,57% of the recommended standard. The optimal economic production occurred with the application on the level of 118,12%. The economic maximum and optimal productions on the biennium generated a gross margin of R$18.205,73/ha and R$ 19.127,81/ha respectively, considering only the costs of fertilizers that was the variable factor.O despreparo gerencial herdado da antiga regulamentação do setor cafeeiro tem interferido nos resultados econômicos da produção. Ao longo dos ciclos produtivos as quantidades de fertilizantes são alteradas sem as devidas recomendações técnicas, podendo inviabilizar economicamente a produção. O produtor, portanto, demanda informações para agir estrategicamente sobre seu negócio. Objetivou-se com este trabalho, analisar a margem de lucro proporcionada pela aplicação de um fertilizante NPK em diferentes níveis em cafeeiros irrigados. As análises contemplaram as safras 2012/2013 e 2013/2014 de um experimento conduzido na Universidade Federal de Lavras. Seu delineamento foi em blocos ao acaso, com seis tratamentos e quatro repetições, sendo seis níveis de adubação com um fertilizante contendo N, P2O5 e K2O que foram de 10, 40, 70, 100, 130 e 160% da recomendação de adubação padrão para cafeeiros de sequeiro. Houve efeito significativo dos níveis de adubação sobre a produtividade no biênio, e a produção máxima foi alcançada com a aplicação do fertilizante no nível de 145,57% da recomendação padrão. A produção ótima econômica ocorreu com a aplicação no nível de 118,12%. As produções máxima e ótima econômica no biênio, geraram uma margem bruta de R$18.205,73 por hectare (ha) e R$ 19.127,81/ha respectivamente, considerando apenas os custos do fertilizante que foi o fator variável

Anopheles aquasalis transcriptome reveals autophagic responses to Plasmodium vivax midgut invasion

BACKGROUND: Elimination of malaria depends on mastering transmission and understanding the biological basis of Plasmodium infection in the vector. The first mosquito organ to interact with the parasite is the midgut and its transcriptomic characterization during infection can reveal effective antiplasmodial responses able to limit the survival of the parasite. The vector response to Plasmodium vivax is not fully characterized, and its specificities when compared with other malaria parasites can be of fundamental interest for specific control measures. METHODS: Experimental infections were performed using a membrane-feeding device. Three groups were used: P. vivax-blood-fed, blood-fed on inactivated gametocytes, and unfed mosquitoes. Twenty-four hours after feeding, the mosquitoes were dissected and the midgut collected for transcriptomic analysis using RNAseq. Nine cDNA libraries were generated and sequenced on an Illumina HiSeq2500. Readings were checked for quality control and analysed using the Trinity platform for de novo transcriptome assembly. Transcript quantification was performed and the transcriptome was functionally annotated. Differential expression gene analysis was carried out. The role of the identified mechanisms was further explored using functional approaches. RESULTS: Forty-nine genes were identified as being differentially expressed with P. vivax infection: 34 were upregulated and 15 were downregulated. Half of the P. vivax-related differentially expressed genes could be related to autophagy; therefore, the effect of the known inhibitor (wortmannin) and activator (spermidine) was tested on the infection outcome. Autophagic activation significantly reduced the intensity and prevalence of infection. This was associated with transcription alterations of the autophagy regulating genes Beclin, DRAM and Apg8. CONCLUSIONS: Our data indicate that P. vivax invasion of An. aquasalis midgut epithelium triggers an autophagic response and its activation reduces infection. This suggests a novel mechanism that mosquitoes can use to fight Plasmodium infection.publishersversionpublishe

Trypanosoma cruzi discrete typing unit TcIV implicated in a case of acute Chagas disease in a domiciliated dog in the western Amazon

Chagas disease is caused by the protozoan Trypanosoma cruzi. Seven lineages have been identified based on different molecular markers, namely TcI, TcII, TcIII, TcIV, TcV, TcVI, and TcBat. Dogs play the role of epidemiological sentinels being domestic reservoirs of T. cruzi. The aim of the current study was to report the first case of CD in a domestic dog in Manaus, Amazonas, Brazil, infected with T. cruzi DTU TcIV. We hope our report encourages veterinarians and surveillance professionals to a take a deeper look at T. cruzi infection in domestic animals.publishersversionpublishe

Produção de palha e desempenho agronômico de soja consorciada com espécies forrageiras em sistema plantio direto

The objective of this work was to evaluate the straw production and the agronomic performance of soybean intercropped with oversown forage species, in no-tillage system. A randomized complete block design was carried out with four replicates, in a 5×2+2 factorial arrangement, as follows: five forage species – Urochloa brizantha 'Marandu', Urochloa ruziziensis, Panicum maximum 'Mombaça', Panicum maximum 'Massai', and Pennisetum americanum –, intercropped with soybean over two crop years (2013/2014 and 2014/2015), plus two controls, with P. americanum sowed in succession to soybean or with soybean monocropping followed by winter fallow (traditional cultivation). Soybean yield components and forage straw yield were evaluated. None of the intercropping systems reduced soybean grain yield, compared with monocropped soybean. The oversown species can significantly improve soybean productivity, as is the case for soybean intercropped with P. maximum 'Mombaça', compared with soybean monocropping, followed or not by millet. Panicum maximum 'Mombaça' is the most effective forage species for dry matter accumulation in the fall/spring period.O objetivo deste trabalho foi avaliar a produção de palha e o desempenho agronômico de soja consorciada com espécies forrageiras sobressemeadas, em sistema plantio direto. Utilizou-se um delineamento de blocos ao acaso, com quatro repetições, em um arranjo fatorial 5x2+2, conforme a seguir: cinco espécies forrageiras – Urochloa brizantha 'Marandu', Urochloa ruziziensis, Panicum maximum 'Mombaça', Panicum maximum 'Massai' e Pennisetum americanum – consorciadas com soja, em duas safras agrícolas (2013/2014 e 2014/2015), além de dois tratamentos-padrão, com P. americanum em sucessão à soja ou com cultivo tradicional de soja e pousio no inverno (soja solteira). Avaliaram-se os componentes de produção da soja e a produtividade de palha das forrageiras. Nenhum dos consórcios diminuiu a produtividade de grãos da soja, em comparação ao cultivo solteiro. As espécies sobressemeadas podem aumentar significativamente a produtividade da soja, como no caso do consórcio da soja com P. maximum 'Mombaça' comparado ao cultivo da soja solteira, com ou sem milheto em sucessão. Panicum maximum 'Mombaça' é a espécie forrageira mais eficiente quanto ao acúmulo de matéria seca, no período outono/primavera

Sensitivity of South American tropical forests to an extreme climate anomaly

The tropical forest carbon sink is known to be drought sensitive, but it is unclear which forests are the most vulnerable to extreme events. Forests with hotter and drier baseline conditions may be protected by prior adaptation, or more vulnerable because they operate closer to physiological limits. Here we report that forests in drier South American climates experienced the greatest impacts of the 2015–2016 El Niño, indicating greater vulnerability to extreme temperatures and drought. The long-term, ground-measured tree-by-tree responses of 123 forest plots across tropical South America show that the biomass carbon sink ceased during the event with carbon balance becoming indistinguishable from zero (−0.02 ± 0.37 Mg C ha −1 per year). However, intact tropical South American forests overall were no more sensitive to the extreme 2015–2016 El Niño than to previous less intense events, remaining a key defence against climate change as long as they are protected