Múltiplos sacos embrionários em ovários do acesso sexual de Brachiaria brizantha (Poaceae).

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Manifestation of finite temperature size effects in nanogranular magnetic graphite

In addition to the double phase transition (with the Curie temperatures T_C=300K and T_{Ct}=144K), a low-temperature anomaly in the dependence of the magnetization is observed in the bulk magnetic graphite (with an average granular size of L=10nm), which is attributed to manifestation of the size effects below the quantum temperature. The best fits of the high-temperature data (using the mean-field Curie-Weiss and Bloch expressions) produced reasonable estimates for the model parameters, such as defects mediated effective spin exchange energy J=12meV (which defines the intragranular Curie temperature T_C) and proximity mediated interactions between neighboring grains (through potential barriers created by thin layers of non-magnetic graphite) with energy J_t=exp(-d/s)J=5.8meV (which defines the intergranular Curie temperature T_{Ct}) with d=1.5nm and s=2nm being the intergranular distance and characteristic length, respectively

Finding a Spherically Symmetric Cosmology from Observations in Observational Coordinates -- Advantages and Challenges

One of the continuing challenges in cosmology has been to determine the large-scale space-time metric from observations with a minimum of assumptions -- without, for instance, assuming that the universe is almost Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW). If we are lucky enough this would be a way of demonstrating that our universe is FLRW, instead of presupposing it or simply showing that the observations are consistent with FLRW. Showing how to do this within the more general spherically symmetric, inhomogeneous space-time framework takes us a long way towards fulfilling this goal. In recent work researchers have shown how this can be done both in the traditional Lema\^{i}tre-Tolman-Bondi (LTB) 3 + 1 coordinate framework, and in the observational coordinate (OC) framework. In this paper we investigate the stability of solutions, and the use of data in the OC field equations including their time evolution and compare both approaches with respect to the singularity problem at the maximum of the angular-diameter distance, the stability of solutions, and the use of data in the field equations. This allows a more detailed account and assessment of the OC integration procedure, and enables a comparison of the relative advantages of the two equivalent solution frameworks. Both formulations and integration procedures should, in principle, lead to the same results. However, as we show in this paper, the OC procedure manifests certain advantages, particularly in the avoidance of coordinate singularities at the maximum of the angular-diameter distance, and in the stability of the solutions obtained. This particular feature is what allows us to do the best fitting of the data to smooth data functions and the possibility of constructing analytic solutions to the field equations.Comment: 31 page

Seed abortion in the sexual counterpart of Brachiaria brizantha apomicts (Poaceae).

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Structural and magnetic properties of CoFe2O4 thin films deposited by laser ablation on Si (001) substrates

Cobalt ferrite (CoFe(2)O(4)) thin films have been deposited on Si (001) substrates, with different substrate ternperatures (Td,p = 25 degrees C - 600 degrees C). The films were prepared by pulsed laser ablation with a KrF excimer laser (wavelength lambda = 248 nm). The oxygen pressure during deposition was 2 x 10(-2) mbar. The films structure was studied by X-ray diffraction (XRD) and their surface was examined by scanning electron microscopy (SEM). The magnetic properties were measured with a vibrating sample magnetometer (VSM). For low deposition temperatures, the films presented a mixture ofa CoFe(2)O(4) phase, with the cubic spinel structure, and cobalt and iron antiferromagnet oxides with CoO and FeO stoichiometries. As the deposition temperature increased, the CoO and FeO relative content strongly decreased, so that for Tdep = 600 degrees C the films were composed mainly by polycrystalline CoFe(2)O(4). The magnetic hysteresis cycles measured in the films were horizontally shifted due to an exchange coupling field (H(exch)) originated by the presence of the antiferromagnetic phases. The exchange field decreased with increasing deposition temperature, and was accompanied by a corresponding increase of the coercivity and remanence ratio of the cycles. This behavior was due to the strong reduction of the CoO and FeO content, and to the corresponding dominance of the CoFe(2)O(4) phase on the magnetic properties of the thin films.This work has been financially supported by the Portuguese Foundation for Science and Technology (FCT), through the project POCI/CTM/60181/2004

Identification of RAPD marker linked to blast resistance gene in a somaclone of rice cultivar Araguaia.

O gene Pi-ar confere resistência para a raça IB-45 de Pyricularia grisea no somaclone derivado de panículas imaturas da cultivar de arroz (Oryza sativa) Araguaia. A técnica RAPD foi usada para identificar marcadores ligados a este gene utilizando a análise de misturas segregantes. Inicialmente o DNA do pai doador resistente SC09 e da cultivar Araguaia foram analisados usando primers arbitrários. Dos 240 primers, 203 produziram produtos amplificados. O DNA dos pais e dos bulks resistente e suscetível da população F2 foram testados usando 48 primers que diferenciaram os pais resistente e suscetível. Enquanto oito primers diferenciaram o bulk resistente do suscetível bem como o somaclone SC09 e Araguaia, somente o primer OPC02 ('GTGAGGCGTC') estava fortemente ligado (1,7cM) ao gene de resistência do somaclone SC09

Avaliação da estratificação do conteúdo ruminal de bubalinos suplementados com farelo de amêndoa de dendê.

Avaliou-se o efeito da suplementação do farelo de amêndoa de dendê, correlacionando com a cinética ruminal, através da estratificação do rúmen e quantificação do volume ocupado pelo conteúdo sólido, líquido e gasoso. O experimento foi conduzido na Unidade de Pesquisa Animal Senador Álvaro Adolpho da Embrapa Amazônia Oriental em Belém, Pará. Foram utilizados quatro bubalinos fistulados no rúmen mantidos em pastagem cultivada com capim Panicum maximum Jacq cv Mombaça em sistema silvipastoril. Os tratamentos experimentais foram a suplementação com um quilograma de farelo de amêndoa de dendê comparado à dieta controle sem suplementação. O conteúdo ruminal foi quantificado em porções sólidas e líquidas e amostrado para determinação de matéria seca. O espaço vazio ruminal foi mensurado com o Método das Bolas. As áreas ocupadas pelas porções sólida, líquida e vazia do rúmen não foram afetada pela suplementação. A porção vazia do rúmen ocupou a menor parte do conteúdo, variando entre 0,007 e 0,017 m3. A porção sólida e líquida do conteúdo ruminal em matéria seca variou entre 6,71 e 9,63 kg nos diversos tratamentos. A conclusão foi que o tempo de esvaziamento não influenciou a estratificação do conteúdo ruminal nas porções líquidas, sólidas e gasosas