Non-Markovian Dynamics of Quantum Discord

We evaluate the quantum discord dynamics of two qubits in independent and common non-Markovian environments. We compare the dynamics of entanglement with that of quantum discord. For independent reservoirs the quantum discord vanishes only at discrete instants whereas the entanglement can disappear during a finite time interval. For a common reservoir, quantum discord and entanglement can behave very differently with sudden birth of the former but not of the latter. Furthermore, in this case the quantum discord dynamics presents sudden changes in the derivative of its time evolution which is evidenced by the presence of kinks in its behavior at discrete instants of time.Comment: 6 pages, 4 figure

A non extensive approach for DNA breaking by ionizing radiation

Tsallis entropy and a maximum entropy principle allows to reproduce experimental data of DNA double strand breaking by electron and neutron radiation. Analytic results for the probability of finding a DNA segment of length l are obtained reproducing quite well the fragment distribution function experimentally obtained

Tolerância ao calor de caprinos e ovinos sem-lã em Sobral.

Resumo: Caprinos das raças Canindé, Anglo-Nubiana e Bhuj e avinos sem-la Morada Nova e Santa Inês foram comparados quanta às temperaturas retais e taxa respiratoria, antes e imediatamente apos o exercício e durante o período de uma hora de repouso apos o0 exercicio, para avaliaçao da tolerância ao calor ambiental. Resultados mostraram que a temperatura retal inicial nao foi diferente entre as cinco raças; apos exercicio, elevou de 1,25ºC até 1,95ºC nas diferentes raças; nao houve diferença da elevaçao da temperatura corporal entre espécies. Apos exercício, a recuperaçao foi rapida nos caprinos Bhuj e Canindé. A recuperaçao foi mais lenta na Anglo-Nubiana e nos avinos. A variaçao inicial no ritmo respiratorio apresentou-se elevada na Anglo-Nubiana em comparaçao com as outras raças de caprinos e avinos. Depois do exercicio, os avinos apresentaram menoI elevaçao no ritmo respiratorio do que os caprinos. Isto pode explicar o grau de recuperaçao mais rapida da temperatura corporal dos caprinos Bhuj e Canindé, os quais tiveram distintamente os mais elevados ritmos respiratorios após o exercicio. 0 ritmo respiratório da Anglo-Nubiana voltou ao normal dentro de 15 minutas apos o exercicio; somente o da Bhuj continuou elevado após os 15 minutos de descanso. Todas as espécies voltaram ao ritmo respiratório normal, após os trinta minutos de descanso. [Heat tolerance of goats and woolless sheep in Sobral Brazil]

Implantação de minibibliotecas escolares: uma iniciativa da Embrapa para agricultores familiares.

A velocidade com que a informação é gerada transforma rapidamente as sociedades. Aqueles que não tem acesso à informação são marginalizados do processo de desenvolvimento social, econômico e tecnológico. Essa distribuição injusta das oportunidades é o ponto de partida da nossa discussão. Nosso foco são as escolas públicas rurais enquanto espaços ?privilegiados? de promoção da inclusão social. O presente artigo apresentará uma análise da experiência de implantação de Minibibliotecas Escolares no Semi-Árido Brasileiro, atualmente com 440 escolas participantes. Disponibiliza também os resultados de uma pesquisa de avaliação realizada entre novembro de 2006 e fevereiro de 2007, com as escolas participantes do projeto. Esses procedimentos fazem parte das ações da Embrapa no Programa Fome Zero desenvolvidas desde 2004, com o intuito de propiciar o repasse de informações e a gestão tecnológica através das escolas da área rural

Echo chamber formation sharpened by priority users

Priority users (e.g., verified profiles on Twitter) are social media users whose content is promoted by recommendation algorithms. However, the impact of this heterogeneous user influence on opinion dynamics, such as polarization phenomena, is unknown. We conduct a computational mechanistic investigation of such consequences in a stylized setting. First, we allow priority users, whose content has greater reach (similar to algorithmic boosting), into an opinion model on adaptive networks. Then, to exploit this gain in influence, we incorporate stubborn user behavior, i.e., zealot users who remain committed to opinions throughout the dynamics. Using a novel measure of echo chamber formation, we find that prioritizing users can inadvertently reduce polarization if they post according to the same rule but sharpen echo chamber formation if they behave heterogeneously. Moreover, we show that a minority of extremist ideologues (i.e., users who are both stubborn and priority) can push the system into a transition from consensus to polarization with echo chambers. Our findings imply that the implementation of the platform's prioritization policy should be carefully monitored in order to ensure there is no abuse of users with extra influence

Fano resonances in plasmonic core-shell particles and the Purcell effect

Despite a long history, light scattering by particles with size comparable with the light wavelength still unveils surprising optical phenomena, and many of them are related to the Fano effect. Originally described in the context of atomic physics, the Fano resonance in light scattering arises from the interference between a narrow subradiant mode and a spectrally broad radiation line. Here, we present an overview of Fano resonances in coated spherical scatterers within the framework of the Lorenz-Mie theory. We briefly introduce the concept of conventional and unconventional Fano resonances in light scattering. These resonances are associated with the interference between electromagnetic modes excited in the particle with different or the same multipole moment, respectively. In addition, we investigate the modification of the spontaneous-emission rate of an optical emitter at the presence of a plasmonic nanoshell. This modification of decay rate due to electromagnetic environment is referred to as the Purcell effect. We analytically show that the Purcell factor related to a dipole emitter oriented orthogonal or tangential to the spherical surface can exhibit Fano or Lorentzian line shapes in the near field, respectively.Comment: 28 pages, 10 figures; invited book chapter to appear in "Fano Resonances in Optics and Microwaves: Physics and Application", Springer Series in Optical Sciences (2018), edited by E. O. Kamenetskii, A. Sadreev, and A. Miroshnichenk

Role of coat colour in body heat regulation among goats and hairy sheep in tropics.

Abstract: This experirnent was conducted during the hottest and the leanest period of the year in the tropical semi-arid northeast of Brazil to evaluate the relative response of black and white va- rieties (with the colour of skin and of haïr being the same) of goats and hairy sheep to grazing under direct solar radiation. There was a marked increase in midside-skin (MS), oar-skin (ES) and rectal temperatures (R T) and respiratory rate (RR) at 2 P .M. The afternoon increase was more in sheep in MS, RT and RR, but ES increased more in goats. Black animais had uniformly higher MS. White sheep had higher ES but in goats colour had no effect. Right ES was higher in sheep and there was some tendency of higher right ES in general. The black goats respired at much higher rates than the white, but in sheep, colour did not influence RR. Colour of animais did not influence RT. There was signi- ticant day-to-day variation, possibly associated with small fluctuations in environmental temperature, in MS, ES and RR but not in RT. The results indicate that goats appear to be better adapted than hairy sheep and white goats better than black goats under local climatic conditions. [Influência da cor da pelagem na regulação do calor em caprinos e ovinos sem-lã no trópico]. Resumo: Este experimento foi conduzido na região tropical do nordeste Brasileiro para avaliar a resposta relativa ao calor dos caprinos e ovinos sem-lã de pelagem (pele + pêlo) branca e preta em pastejo e expostos diretamente à radiação solar. Houve um aumento marcante nas temperaturas da pele da costela (PC), pele da orelha (PO) e retal (TR) e no rítmo respiratório (RR) às 14h. À tarde, a elevação foi maior em ovinos na PC, TR e no RR, mas PO aumentou mais nos caprinos. Animais pretos tinham, uniformemente, maior PC. Os ovinos brancos exibiram maior PO, mas no caprinos a cor não influenciou. ES direita foi superior em ovinos e houve tendência da PO direita ser, em geral, superior. Caprinos de cor preta apresentaram maior elevação no RR do que os de cor branca, mas nos ovinos a cor não influenciou o RR. Cor da pelagem não teve influência na TR. Houve uma variação diária significante na PC, PO e RR, mas não na TR, possivelmente associado com flutuações na temperatura ambiental. Resultados indicam que caprinos parecem ser melhor adaptados do que ovinos sem-lã e caprinos brancos melhor que caprinos pretos sob as condições climáticas locais

Potencial alelopático de catequinas de Tachigali myrmecophyla (leguminosae).

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