16,857 research outputs found
Majority-vote on undirected Barabasi-Albert networks
On Barabasi-Albert networks with z neighbours selected by each added site,
the Ising model was seen to show a spontaneous magnetisation. This spontaneous
magnetisation was found below a critical temperature which increases
logarithmically with system size. On these networks the majority-vote model
with noise is now studied through Monte Carlo simulations. However, in this
model, the order-disorder phase transition of the order parameter is well
defined in this system and this wasn't found to increase logarithmically with
system size. We calculate the value of the critical noise parameter q_c for
several values of connectivity of the undirected Barabasi-Albert network.
The critical exponentes beta/nu, gamma/nu and 1/nu were calculated for several
values of z.Comment: 15 pages with numerous figure
Constraints on Cold Dark Matter Accelerating Cosmologies and Cluster Formation
We discuss the properties of homogeneous and isotropic flat cosmologies in
which the present accelerating stage is powered only by the gravitationally
induced creation of cold dark matter (CCDM) particles (). For
some matter creation rates proposed in the literature, we show that the main
cosmological functions such as the scale factor of the universe, the Hubble
expansion rate, the growth factor and the cluster formation rate are
analytically defined. The best CCDM scenario has only one free parameter and
our joint analysis involving BAO + CMB + SNe Ia data yields
() where
is the observed matter density parameter. In particular, this implies that the
model has no dark energy but the part of the matter that is effectively
clustering is in good agreement with the latest determinations from large scale
structure. The growth of perturbation and the formation of galaxy clusters in
such scenarios are also investigated. Despite the fact that both scenarios may
share the same Hubble expansion, we find that matter creation cosmologies
predict stronger small scale dynamics which implies a faster growth rate of
perturbations with respect to the usual CDM cosmology. Such results
point to the possibility of a crucial observational test confronting CCDM with
CDM scenarios trough a more detailed analysis involving CMB, weak
lensing, as well as the large scale structure.Comment: 12 pages, 3 figures, Accepted for publication by Physical Rev.
Crescimento de genótipos de mamoeiro cultivados sob condições salinas.
Nos estados da Bahia e do Espírito Santo, principais regiões produtoras de mamão do Brasil, essa cultura está concentrada no ecossistema dos Tabuleiros Costeiros, onde são registradas, em alguns meses, precipitações inferiores à demanda da cultura. Assim para que o mamoeiro alcance altas produtividades o emprego de irrigações suplementares constitui-se em uma prática importante e imprescindível.Em paralelo aconteceram também os seguintes eventos: V Seminário de Pesquisa do Recôncavo da Bahia; V Seminário Estudantil de Pesquisa da UFRB; V Seminário da Pós-Graduação da UFRB; II Seminário Regional de Pesquisa da EBDA; 5ª Jornada Científica da Embrapa Mandioca e Fruticultura; VIII Seminário Estudantil de Pesquisa e Extensão da FAMAM; Semana de Ciência, Tecnologia e Inovação no Agronegócio; Fórum de Gestores de Iniciação Científica e Tecnológica da Bahia; II Simpósio Baiano de Defesa Agropecuária; I Semana de Educação Tutorial da UFRB
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