Sedimentation of Oblate Ellipsoids at low and Moderate Reynolds numbers

In many applications to biophysics and environmental engineering, sedimentation of non-spherical particles for example: ellipsoids, is an important problem. In our work, we simulate the dynamics of oblate ellipsoids under gravity. We study the settling velocity and the average orientation of the ellipsoids as a function of volume fraction. We see that the settling velocity shows a local maximum at the intermmediate densities unlike the spheres. The average orientation of the ellipsoids also shows a similar local maximum and we observe that this local maximum disappears as the Reynolds number is increased. Also, at small volume fractions, we observe that the oblate ellipsoids exhibit an orientational clustering effect in alignment with gravity accompanied by strong density fluctuations. The vertical and horizontal fluctuations of the oblate ellipsoids are small compared to that of the spheres

The Green New Deal and Evolution of Institutional Environments for Multifunctionality: the case of Certified Organic Agriculture in Brazil and China

The Global Green New Deal (GGND) aim to green the global economy across a range of sectors including agriculture, to pursue future prosperity and job creation, while at the same time addressing social and environmental challenges. Taking its point of departure in some of the institutional changes envisioned in GGND publications, the paper proceeds to present results of the authors’ current research, within a research programme on institutional dimensions of the current globalization of certified organic agriculture. Case study results from Brazil and China are used to illustrate how institutional environments for organic agriculture differ between nations and to provide a basis for discussing the potential of organic certification to transform global agriculture towards higher overall levels of sustainability. The paper concludes linking the institutional analysis of the GGND and the findings of the presented cases to a broader analysis and discussion on the state of art of institutional environments for multifunctional agriculture

Seismic vulnerability of Modern Architecture building's: Le Corbusier style: a case study

In Portugal, at the end of the World War II, a new generation of architects emerged, influenced by the Modern Movement Architecture, born in Central-Europe in the early twenties but now influenced also by the Modern Brazilian Architecture. They worked with new typologies, such as multifamily high-rise buildings, and built them in the most important cities of the country, during the fifties, reflecting the principles of the Modernity and with a strong formal conception inspired in the International Style’s codes. Concrete, as material and technology, allowed that those “Unity Centre” buildings become modern objects, expressing the five-point formula that Le Corbusier enounced in 1927 and draw at the “Unité d’Habitation de Marseille”, namely: the building lifted in pilotis, the free design of the plan, the free design of the façade, the unbroken horizontal window and the roof terrace. In Lisbon, late forties urban plans transformed and expanded the city, creating modulated buildings repeated in great extensions – that was a progressist idea of standardization. The Infante Santo complex is a successful adaptation to the Lisbon reality of the Modern Urbanism and Architecture. In the fifties, it was built a large number of Modern housing buildings in Lisbon, with structural characteristics that, in certain conditions, can induce weaknesses in structural behaviour, especially under earthquake loading. For example, the concept of buildings lifted in pilotis can strongly facilitate the occurrence of soft-storey mechanisms, which turns these structures very vulnerable to earthquake actions. The development and calibration of refined numerical tools, as well as, assessment and design codes makes feasible the structural safety assessment of existing buildings. To investigate the vulnerability of this type of construction, one building representative of the Modern Architecture, at the Infante Santo Avenue, was studied. This building was studied with the non-linear dynamic analysis program PORANL, which allows the safety evaluation according to the recently proposed standards

The eigenpairs of a Sylvester-Kac type matrix associated with a simple model for one-dimensional deposition and evaporation

A straightforward model for deposition and evaporation on discrete cells of a finite array of any dimension leads to a matrix equation involving a Sylvester-Kac type matrix. The eigenvalues and eigenvectors of the general matrix are determined for an arbitrary number of cells. A variety of models to which this solution may be applied are discussed.Comment: 7 pages, no figure

Four-nucleon scattering: Ab initio calculations in momentum space

The four-body equations of Alt, Grassberger and Sandhas are solved for \nH scattering at energies below three-body breakup threshold using various realistic interactions including one derived from chiral perturbation theory. After partial wave decomposition the equations are three-variable integral equations that are solved numerically without any approximations beyond the usual discretization of continuum variables on a finite momentum mesh. Large number of two-, three- and four-nucleon partial waves are considered until the convergence of the observables is obtained. The total \nH cross section data in the resonance region is not described by the calculations which confirms previous findings by other groups. Nevertheless the numbers we get are slightly higher and closer to the data than previously found and depend on the choice of the two-nucleon potential. Correlations between the $A_y$ deficiency in \nd elastic scattering and the total \nH cross section are studied.Comment: Corrected Eq. (10

Dynamical star-disk interaction in the young stellar system V354 Mon

The main goal of this work is to characterize the mass accretion and ejection processes of the classical T Tauri star V354 Mon, a member of the young stellar cluster NGC 2264. In March 2008, photometric and spectroscopic observations of V354 Mon were obtained simultaneously with the CoRoT satellite, the 60 cm telescope at the Observat\'orio Pico dos Dias (LNA - Brazil) equipped with a CCD camera and Johnson/Cousins BVRI filters, and the SOPHIE \'echelle spectrograph at the Observatoire de Haute-Provence (CNRS - France). The light curve of V354 Mon shows periodical minima (P = 5.26 +/- 0.50 days) that vary in depth and width at each rotational cycle. From the analysis of the photometric and spectroscopic data, it is possible to identify correlations between the emission line variability and the light-curve modulation of the young system, such as the occurrence of pronounced redshifted absorption in the H_alpha line at the epoch of minimum flux. This is evidence that during photometric minima we see the accretion funnel projected onto the stellar photosphere in our line of sight, implying that the hot spot coincides with the light-curve minima. We applied models of cold and hot spots and a model of occultation by circumstellar material to investigate the source of the observed photometric variations. We conclude that nonuniformly distributed material in the inner part of the circumstellar disk is the main cause of the photometric modulation, which does not exclude the presence of hot and cold spots at the stellar surface. It is believed that the distortion in the inner part of the disk is created by the dynamical interaction between the stellar magnetosphere, inclined with respect to the rotation axis, and the circumstellar disk, as also observed in the classical T Tauri star AA Tau and predicted by magnetohydrodynamical numerical simulations.Comment: Accepted by Astronomy and Astrophysic