Magnetic Properties of the Metamagnet Ising Model in a three-dimensional Lattice in a Random and Uniform Field

By employing the Monte Carlo technique we study the behavior of Metamagnet Ising Model in a random field. The phase diagram is obtained by using the algorithm of Glaubr in a cubic lattice of linear size $L$ with values ranging from 16 to 42 and with periodic boundary conditions.Comment: 4 pages, 6 figure

Economicidade do cultivo da soca de arroz irrigado em várzeas tropicais.

A análise econômica baseou-se nas produtividades médias obitdas no cultivo principal e na soca, no sistema de produção do arroz irrigado empregado pelos produtores, considerando-se os custos variáveis, as receitas e as relações de benefício/custo, conforme planilha eletrônica utilizada para cálculos na Embrapa Arroz e Feijão, com os preços atualizados no mês de abril de 2003.bitstream/CNPAF/21523/1/comt_59.pd

Base de dados geográficos como subsídio à gestão territorial na fazenda experimental da Embrapa Amazônia Oriental, Belém, PA.

bitstream/item/61586/1/CPATU-BPD77.pdfAnexo 4 mapas: Solos da Fazenda Experimental da Embrapa Amazônia Oriental, Belém, PA; Uso atual das terras da Fazenda Experimental da Embrapa Amazônia Oriental, Belém, PA; Restrição legal ao uso da terra da Fazenda Experimental da Embrapa Amazônia Oriental, Belém, PA.Zoneamento agroecológico da Fazenda Experimental da Embrapa Amazônia Oriental, Belém, PA

Evaluation of brazilian dairy goat breeding programs.

Abstract: This work aimed to evaluate the genetic and economic gains for two selection schemes for dairy goats in Brazil. Analyses were performed by ZPLAN software. The traditional scheme had no economic viability, except with high levels (>=60%) of using nucleus bucks on commercial flocks. However, this has no practical feasibility due the low use of artificial insemination in Brazil. The progeny testing of young bucks presented viability, with considerable genetic gains for the selection objective and the individual traits that make up this goal. The economic returns of the program outweighed its costs, with an investment return of 20 %. In this scheme, the trait of greater economic impact was milk yield followed by somatic cell count. The amount of using of young bucks should be up to 15 % since higher levels reduce the economic efficiency of the program

Evidence for entanglement at high temperatures in an engineered molecular magnet

The molecular compound [Fe$_{2}$($\mu_{2}$-oxo)(C$_{3}$H$_{4}$N$_{2}$)$_{6}$(C$_{2}$O$_{4}$)$_{2}$] was designed and synthesized for the first time and its structure was determined using single-crystal X-ray diffraction. The magnetic susceptibility of this compound was measured from 2 to 300 K. The analysis of the susceptibility data using protocols developed for other spin singlet ground-state systems indicates that the quantum entanglement would remain at temperatures up to 732 K, significantly above the highest entanglement temperature reported to date. The large gap between the ground state and the first-excited state (282 K) suggests that the spin system may be somewhat immune to decohering mechanisms. Our measurements strongly suggest that molecular magnets are promising candidate platforms for quantum information processing

Electronic doping of graphene by deposited transition metal atoms

We perform a phenomenological analysis of the problem of the electronic doping of a graphene sheet by deposited transition metal atoms, which aggregate in clusters. The sample is placed in a capacitor device such that the electronic doping of graphene can be varied by the application of a gate voltage and such that transport measurements can be performed via the application of a (much smaller) voltage along the graphene sample, as reported in the work of Pi et al. [Phys. Rev. B 80, 075406 (2009)]. The analysis allows us to explain the thermodynamic properties of the device, such as the level of doping of graphene and the ionisation potential of the metal clusters in terms of the chemical interaction between graphene and the clusters. We are also able, by modelling the metallic clusters as perfect conducting spheres, to determine the scattering potential due to these clusters on the electronic carriers of graphene and hence the contribution of these clusters to the resistivity of the sample. The model presented is able to explain the measurements performed by Pi et al. on Pt-covered graphene samples at the lowest metallic coverages measured and we also present a theoretical argument based on the above model that explains why significant deviations from such a theory are observed at higher levels of coverage.Comment: 16 pages, 10 figure