Construction of Nonlinear Symplectic Six-Dimensional Thin-Lens Maps by Exponentiation

The aim of this paper is to construct six-dimensional symplectic thin-lens transport maps for the tracking program SIXTRACK, continuing an earlier report by using another method which consistes in applying Lie series and exponentiation as described by W. Groebner and for canonical systems by A.J. Dragt. We firstly use an approximate Hamiltonian obtained by a series expansion of the square root. Furthermore, nonlinear crossing terms due to the curvature in bending magnets are neglected. An improved Hamiltonian, excluding solenoids, is introduced in Appendix A by using the unexpanded square root mentioned above, but neglecting again nonlinear crossing terms...Comment: 57 pages, late

Uso do modelo de simulação Oryza/Apsim 2000 na definição da população de plantas para o arroz de terras altas.

Com este trabalho se propôs simular a resposta do arroz de terras altas a diferentes populações de plantas, em várias épocas de semeadura, com o modelo de simulação do crescimento, desenvolvimento e produtividade ORYZA/APSIM 2000, visando maximizar a produtividade dessa cultura. Para tanto, considerou-se as populações de plantas de 100, 150, 250 e 450 plantas m-2, as quais foram combinadas com cinco datas de semeadura: 01/11, 15/11, 01/12, 15/12 e 31/12. A produtividade de grãos simulada do arroz de terras altas apresentou resposta quadrática à população de plantas, com valores máximos sendo alcançados com populações acima de 350 plantas m-2. Contudo, considerando a maior eficiência técnica, as menores populações de plantas testadas são as mais adequadas. Há maior probabilidade de se obter altas produtividades de arroz de terras altas em datas de semeadura precoces, a partir de 01/11.bitstream/item/46422/1/boletimdepesquisa-36.pd

Determining optimum sowing date for early upland rice cultivar using modelling approach.

The objective of this study was to determine the optimum sowing date for early upland rice cultivar at Santo Antonio de Goiás, GO, Brazil. To optimize solar radiation and precipitation during the upland rice sowing period (from November to December) it was used the crop model RICE06 from Ecotrop plataform. To mimic the conditions of region, two scenarios were created: a) no restriction to root development (0.8 m effective root depth) and b) restrictions to root development (Al toxic in the subsoil ? 0.4 m effective root depth). The crop model was run based on the climate historical date (22 years of daily data for precipitation, solar radiation, maximum and minimum temperature, maximum and minimum relative humidity, and wind speed) collected at Embrapa Rice & Beans weather station. Five different sowing dates (01/11, 15/11, 1/12, 15/12, and 31/12) were taken into account. The decision criterions used to determine the optimum sowing date were the variability, comparison of exceedance probability and mean variation for yield and the averaged index stress factor. The results obtained showed that the optimum sowing date for both scenarios was 15-Nov

Kantorovich-Rubinstein Distance and Barycenter for Finitely Supported Measures: Foundations and Algorithms

The purpose of this paper is to provide a systematic discussion of a generalized barycenter based on a variant of unbalanced optimal transport (UOT) that defines a distance between general non-negative, finitely supported measures by allowing for mass creation and destruction modeled by some cost parameter. They are denoted as Kantorovich–Rubinstein (KR) barycenter and distance. In particular, we detail the influence of the cost parameter to structural properties of the KR barycenter and the KR distance. For the latter we highlight a closed form solution on ultra-metric trees. The support of such KR barycenters of finitely supported measures turns out to be finite in general and its structure to be explicitly specified by the support of the input measures. Additionally, we prove the existence of sparse KR barycenters and discuss potential computational approaches. The performance of the KR barycenter is compared to the OT barycenter on a multitude of synthetic datasets. We also consider barycenters based on the recently introduced Gaussian Hellinger–Kantorovich and Wasserstein–Fisher–Rao distances

Response of traditional and modern upland rice cultivars to drought.

Two modern cultivars and one traditional cultivar were submitted to two water regimes, potential growth and water deficit, after the panicle differentiation. It was observed that modern upland rice cultivars had different response to drought than traditional cultivar

Resistive double-diffusive instability in the dead-zones of protostellar disks

We outline a novel linear instability that may arise in the dead-zones of protostellar disks, and possibly the fluid interiors of planets and protoplanets. In essence it is an axisymmetric buoyancy instability, but one that would not be present in a purely hydrodynamical gas. The necessary ingredients for growth include a negative radial entropy gradient (of any magnitude), weak magnetic fields, and efficient resistive diffusion (in comparison with thermal diffusion). The character of the instability is local, axisymmetric, and double-diffusive, and it attacks lengths much shorter than the resistive scale. Like the axisymmetric convective instability, it draws its energy from the negative radial entropy gradient; but by utilising the diffusing magnetic field, it can negate the stabilising influence of rotation. Its nonlinear saturated state, while not transporting appreciable angular momentum, could drive radial and vertical mixing, which may influence the temperature structure of the disk, dust dynamics and, potentially, planet formation.Comment: 16 pages, 5 figures. MNRAS Accepted. V2: cosmetic changes to bring in line with MNRAS versio

Myosin motors fragment and compact membrane-bound actin filaments

Cell cortex remodeling during cell division is a result of myofilament-driven contractility of the cortical membrane-bound actin meshwork. Little is known about the interaction between individual myofilaments and membrane-bound actin filaments. Here we reconstituted a minimal actin cortex to directly visualize the action of individual myofilaments on membrane-bound actin filaments using TIRF microscopy. We show that synthetic myofilaments fragment and compact membrane-bound actin while processively moving along actin filaments. We propose a mechanism by which tension builds up between the ends of myofilaments, resulting in compressive stress exerted to single actin filaments, causing their buckling and breakage. Modeling of this mechanism revealed that sufficient force (∼20 pN) can be generated by single myofilaments to buckle and break actin filaments. This mechanism of filament fragmentation and compaction may contribute to actin turnover and cortex reorganization during cytokinesis

Vote buying or (Political) business (cycles) as usual?

We report robust evidence of a new short-run monetary election cycle: the monthly growth rate of the money supply (M1) around elections is higher than in other months in a sample of low- and middle-income countries. We hypothesize this is related to systemic vote buying. Consistent with this, we find no cycle in authoritarian countries and countries with strong political institutions and a pronounced cycle in elections where international election monitors reported vote buying or in close elections. Using survey data on daily consumer expenditures, we show that within-household consumption of food increases in the days before elections. </jats:p

Caracteres morfológicos do crescimento e desenvolvimento de quatro cultivares de arroz de terras altas.

Esse estudo teve como objetivo identificar e comparar os principais processos morfológicos relacionados ao desenvolvimento e crescimento de quatro diferentes cultivares de arroz de terras altas na fase vegetativa.bitstream/CNPAF-2009-09/27968/1/doc_229.pd