Subproton-scale cascades in solar wind turbulence: driven hybrid-kinetic simulations

A long-lasting debate in space plasma physics concerns the nature of subproton-scale fluctuations in solar wind (SW) turbulence. Over the past decade, a series of theoretical and observational studies were presented in favor of either kinetic Alfv\'en wave (KAW) or whistler turbulence. Here, we investigate numerically the nature of the subproton-scale turbulent cascade for typical SW parameters by means of unprecedented high-resolution simulations of forced hybrid-kinetic turbulence in two real-space and three velocity-space dimensions. Our analysis suggests that small-scale turbulence in this model is dominated by KAWs at $\beta\gtrsim1$ and by magnetosonic/whistler fluctuations at lower $\beta$. The spectral properties of the turbulence appear to be in good agreement with theoretical predictions. A tentative interpretation of this result in terms of relative changes in the damping rates of the different waves is also presented. Overall, the results raise interesting new questions about the properties and variability of subproton-scale turbulence in the SW, including its possible dependence on the plasma $\beta$, and call for detailed and extensive parametric explorations of driven kinetic turbulence in three dimensions.Comment: 6 pages, 4 figures, accepted for publication in The Astrophysical Journal Letter

Comparação entre metodologias para cálculo do índice de manejo de carbono do solo em São Luís-MA.

O objetivo desse trabalho foi comparar o IMC calculado a partir de duas metodologias para determinação do teor de C lábil do solo (oxidação do C por K2Cr2O7 em diferentes níveis de acidez e fracionamento físico da matéria orgânica do solo) em solos sob diferentes usos em São Luís-MA

Emissões de N2O de um latossolo após a aplicação de fertilizantes nitrogenados.

O óxido nitroso (N2O) é o principal gás do efeito estufa emitido pelos solos agrícolas e sua emissão é influenciada pelo uso de fertilizantes nitrogenados. Este trabalho avaliou, sob condições controladas, o comportamento das emissões de N2O em amostras de um Latossolo Vermelho, em função da aplicação de duas fontes (nitrato de amônio e ureia) e de três doses (0,11 mg; 0,15 mg e 0,22 mg de N g-1 de solo) de nitrogênio. Os tratamentos foram aplicados na forma de solução, em delineamento inteiramente casualizado, com quatro repetições. Todos os tratamentos aumentaram as emissões de N2O em relação ao controle. O efeito da dose de N sobre as emissões de N2O foi mais pronunciado para a ureia. As emissões foram maiores e ocorreram mais rapidamente nos tratamentos com ureia do que naqueles com nitrato de amônio (maior emissão diária aos 9 e aos 12 dias, respectivamente). As emissões acumuladas ajustaram-se adequadamente a modelos logísticos em todos os tratamentos, indicando que estas curvas representam bem as emissões de N2O induzidas pela aplicação de fertilizantes nitrogenados sob condições controladas. Os resultados podem auxiliar no planejamento de pesquisas similares a serem conduzidas no campo

Comparing persistence diagrams through complex vectors

The natural pseudo-distance of spaces endowed with filtering functions is precious for shape classification and retrieval; its optimal estimate coming from persistence diagrams is the bottleneck distance, which unfortunately suffers from combinatorial explosion. A possible algebraic representation of persistence diagrams is offered by complex polynomials; since far polynomials represent far persistence diagrams, a fast comparison of the coefficient vectors can reduce the size of the database to be classified by the bottleneck distance. This article explores experimentally three transformations from diagrams to polynomials and three distances between the complex vectors of coefficients.Comment: 11 pages, 4 figures, 2 table

Collision-dependent power law scalings in 2D gyrokinetic turbulence

Nonlinear gyrokinetics provides a suitable framework to describe short-wavelength turbulence in magnetized laboratory and astrophysical plasmas. In the electrostatic limit, this system is known to exhibit a free energy cascade towards small scales in (perpendicular) real and/or velocity space. The dissipation of free energy is always due to collisions (no matter how weak the collisionality), but may be spread out across a wide range of scales. Here, we focus on freely-decaying 2D electrostatic turbulence on sub-ion-gyroradius scales. An existing scaling theory for the turbulent cascade in the weakly collisional limit is generalized to the moderately collisional regime. In this context, non-universal power law scalings due to multiscale dissipation are predicted, and this prediction is confirmed by means of direct numerical simulations.Comment: 7 pages, 5 figures, accepted for publication in Physics of Plasma

Graphic-based concept retrieval

Two ways of expressing concepts in the context of image retrieval are presented. One, Keypics, is on the side of an image owner, who wants the image itself to be found on the Web; the second, Trittico, is on the side of the image searcher. Both are based on the paradigm of human intermediation for overcoming the semantic gap. Both require tools capable of qualitative analysis, and have been experimented by using persistent homology

Nitrous oxide emissions in agricultural soils: a review.

The greenhouse gases concentration in the atmosphere have significantly increased since the beginning of the Industrial Revolution. The most important greenhouse gases are CO2, CH4 and N2O, with CH4 and N2O presenting global warming potentials 25 and 298 times higher than CO2, respectively. Most of the N2O emissions take place in soils and are related with agricultural activities. So, this review article aimed at presenting the mechanisms of N2O formation and emission in agricultural soils, as well as gathering and discussing information on how soil management practices may be used to reduce such emissions. The N2O formation in the soil occurs mainly through nitrification and denitrification processes, which are influenced by soil moisture, temperature, oxygen concentration, amount of available organic carbon and nitrogen and soil C/N ratio. Among these factors, those related to soil could be easily altered by management practices. Therefore, understanding the processes of N2O formation in soils and the factors influencing these emissions is fundamental to develop efficient strategies to reduce N2O emissions in agricultural soils

PIN15 CHRONIC HEPATITIS B (CHB) MANAGEMENT COSTS IN SWEDEN

L'edifici fou construït l'any 1860, aproximadament.Primer pla, contrapicat d'un edifici d'habitatges entre mitgeres, en cantonada. Consta de planta baixa, cinc plantes pis i terrat. La façana és uniforme, de marcat estil academicista, amb un pòrtic amb pilars i arcs de mig punt a la planta baixa