Sobre el género Gratiola L. (Scrophulariaceae) en el norte de Marruecos y Andalucía.

La preparación de las síntesis del género Gratiola para Flora iberica y BIOGEO ha propiciado la consulta y revisión de materiales del herbario marroquíes, andaluces y de otras procedencias

Dynamics and Kinetic Roughening of Interfaces in Two-Dimensional Forced Wetting

We consider the dynamics and kinetic roughening of wetting fronts in the case of forced wetting driven by a constant mass flux into a 2D disordered medium. We employ a coarse-grained phase field model with local conservation of density, which has been developed earlier for spontaneous imbibition driven by a capillary forces. The forced flow creates interfaces that propagate at a constant average velocity. We first derive a linearized equation of motion for the interface fluctuations using projection methods. From this we extract a time-independent crossover length $\xi_\times$, which separates two regimes of dissipative behavior and governs the kinetic roughening of the interfaces by giving an upper cutoff for the extent of the fluctuations. By numerically integrating the phase field model, we find that the interfaces are superrough with a roughness exponent of $\chi = 1.35 \pm 0.05$, a growth exponent of $\beta = 0.50 \pm 0.02$, and $\xi_\times \sim v^{-1/2}$ as a function of the velocity. These results are in good agreement with recent experiments on Hele-Shaw cells. We also make a direct numerical comparison between the solutions of the full phase field model and the corresponding linearized interface equation. Good agreement is found in spatial correlations, while the temporal correlations in the two models are somewhat different.Comment: 9 pages, 4 figures, submitted to Eur.Phys.J.

Remarks on Bootstrap Percolation in Metric Networks

We examine bootstrap percolation in d-dimensional, directed metric graphs in the context of recent measurements of firing dynamics in 2D neuronal cultures. There are two regimes, depending on the graph size N. Large metric graphs are ignited by the occurrence of critical nuclei, which initially occupy an infinitesimal fraction, f_* -> 0, of the graph and then explode throughout a finite fraction. Smaller metric graphs are effectively random in the sense that their ignition requires the initial ignition of a finite, unlocalized fraction of the graph, f_* >0. The crossover between the two regimes is at a size N_* which scales exponentially with the connectivity range \lambda like_* \sim \exp\lambda^d. The neuronal cultures are finite metric graphs of size N \simeq 10^5-10^6, which, for the parameters of the experiment, is effectively random since N<< N_*. This explains the seeming contradiction in the observed finite f_* in these cultures. Finally, we discuss the dynamics of the firing front

Evolucao da erosividade das chuvas na Bacia do Alto Taquari.

O assoreamento do rio Taquari constitui hoje um dos mais graves e discutidos problemas de impacto ambiental e socio economicos do Pantanal. Apesar do rio Taquari, historicamente, transportar grande quantidade de sedimento, a partir do final da decada de 70 esse processo foi intensificado com a expansao da atividade agropecuaria na Bacia do Alto Taquari (BAT). Outro fator importante no aumento do aporte de sedimento para o Pantanal pode estar relacionado a mudanca no regime pluviometrico na BAT. O calculo do indice mensal de erosividade da chuva foi efetuado para dois periodos: de 1969/70 a 1972/73 (periodo 1) e de 1973/74 A 1987/88 (periodo 2), utilizando o metodo de Lombardi Neto. Foram selecionadas cinco estacoes pluviometricas localizadas na BAT que tinham pelo menos cinco anos de registro de dados de chuva no periodo 1. Analisou-se, tambem, as medias mensais de precipitacao para os mesmos periodos. Os resultados das analises estatisticas evidenciaram um aumento significativo no regime pluviometrico e consequentemente na erosividade das chuvas na BAT, entre o periodo de 1969-70/1973-74 para o periodo de 1974-75/1987-88.bitstream/item/37427/1/BP25.pd

Reading Remediation Program for Struggling Readers: An Impact Study

One of the most important aspects of education is reading, which is essential to progress in a literate society. It is important then to speed up reading through reading programs. Reading remediation is a supplemental reading program that focuses on correct phonological processes. The study established the value of reading remediation as a tool for helping struggling readers in grade 2 to learn more effectively. In particular, it sought to ascertain how the program had affected a child's reading ability before and after its implementation. The experimental pretest-posttest research design was used for this investigation. Microsoft Excel was utilized to simplify the statistical computation of the data. Results showed that the respondents' performance ratings in the pretest were poor, but they were good in the post-test, indicating that there is an improvement in performance after giving struggling readers reading remediation. Therefore, the Reading Remediation is a useful tool for improving learning for the struggling grade 2 readers of Sevilla Elementary School

Probing the Dark Dimension with Auger data

[Abridged] By combining swampland conjectures with observational data, it was recently noted that our universe could stretch off in an asymptotic region of the string landscape of vacua. In this framework, the cosmological hierarchy problem can be resolved by the addition of one mesoscopic (dark) dimension of size $\sim \lambda \, \Lambda^{-1/4} \sim 1~\mu{\rm m}$. The Planck scale of the higher dimensional theory, $M_{\rm UV} \sim \lambda^{-1/3} \Lambda^{1/12} M_{\rm Pl}^{2/3} \sim 10^{10}~{\rm GeV}$, is tantalizingly close to the energy above which the TA and Auger collaborations found conclusive evidence for a sharp cutoff of the flux of UHECRs. It was recently suggested that since physics becomes strongly coupled to gravity beyond $M_{\rm UV}$, universal features deep-rooted in the dark dimension could control the energy cutoff of the source spectra. Conversely, in the absence of phenomena inborn within the dark dimension, we would expect a high variance of the cosmic ray maximum energy characterizing the source spectra, reflecting the many different properties inherent to the most commonly assumed UHECR accelerators. A recent analysis of Auger and TA data exposed strong evidence for a correlation between UHECRs and nearby starburst galaxies, with a global significance post-trial of $4.7\sigma$. Since these galaxies are in our cosmic backyard, the flux attenuation factor due to cosmic ray interactions en route to Earth turns out to be negligible. This implies that for each source, the shape of the observed spectrum should roughly match the emission spectrum, providing a unique testing ground for the dark dimension hypothesis. Using Auger data, we carry out a maximum likelihood analysis to characterize the shape of the UHECR emission from the galaxies dominating the anisotropy signal. We show that the observed spectra could be universal only if $\lambda \lesssim 10^{-3}$.Comment: 17 pages, 3 figure

Anomalous Roughening in Experiments of Interfaces in Hele-Shaw Flows with Strong Quenched Disorder

We report experimental evidences of anomalous kinetic roughening in the stable displacement of an oil-air interface in a Hele-Shaw cell with strong quenched disorder. The disorder consists on a random modulation of the gap spacing transverse to the growth direction (tracks). We have performed experiments varying average interface velocity and gap spacing, and measured the scaling exponents. We have obtained beta=0.50, beta*=0.25, alpha=1.0, alpha_l=0.5, and z=2. When there is no fluid injection, the interface is driven solely by capillary forces, and a higher value of beta around beta=0.65 is measured. The presence of multiscaling and the particular morphology of the interfaces, characterized by high slopes that follow a L\'evy distribution, confirms the existence of anomalous scaling. From a detailed study of the motion of the oil--air interface we show that the anomaly is a consequence of different local velocities over tracks plus the coupling in the motion between neighboring tracks. The anomaly disappears at high interface velocities, weak capillary forces, or when the disorder is not sufficiently persistent in the growth direction. We have also observed the absence of scaling when the disorder is very strong or when a regular modulation of the gap spacing is introduced.Comment: 14 pages, 17 figure

Monitoramento do comportamento do rio Paraguai no Pantanal Sul-Mato-grossense-2008/2009.

Este trabalho visa dar continuidade ao programa de monitoramento do comportamento do rio Paraguai que é feito anualmente pela Embrapa Pantanal.bitstream/CPAP-2010/57313/1/COT80.pd

Precise Modeling of the Exoplanet Host Star and CoRoT Main Target HD 52265

This paper presents a detailed and precise study of the characteristics of the Exoplanet Host Star and CoRoT main target HD 52265, as derived from asteroseismic studies. The results are compared with previous estimates, with a comprehensive summary and discussion. The basic method is similar to that previously used by the Toulouse group for solar-type stars. Models are computed with various initial chemical compositions and the computed p-mode frequencies are compared with the observed ones. All models include atomic diffusion and the importance of radiative accelerations is discussed. Several tests are used, including the usual frequency combinations and the fits of the \'echelle diagrams. The possible surface effects are introduced and discussed. Automatic codes are also used to find the best model for this star (SEEK, AMP) and their results are compared with that obtained with the detailed method. We find precise results for the mass, radius and age of this star, as well as its effective temperature and luminosity. We also give an estimate of the initial helium abundance. These results are important for the characterization of the star-planet system.Comment: 9 pages, 6 figures, 7 tables, to be published in Astronomy and Astrophysic