Collision free region determination by modified polygonal Boolean operations

Cutting and packing problems are found in numerous industries such as garment, wood and shipbuilding. The collision free region concept is presented, as it represents all the translations possible for an item to be inserted into a container with already placed items. The often adopted nofit polygon concept and its analogous concept inner fit polygon are used to determine the collision free region. Boolean operations involving nofit polygons and inner fit polygons are used to determine the collision free region. New robust non-regularized Boolean operations algorithm is proposed to determine the collision free region. The algorithm is capable of dealing with degenerated boundaries. This capability is important because degenerated boundaries often represent local optimal placements. A parallelized version of the algorithm is also proposed and tests are performed in order to determine the execution times of both the serial and parallel versions of the algorithm.

Insights into the morphology of the Serra da Cangalha impact structure from geophysical modeling

Forward modeling is commonly applied to gravity field data of impact structures to determine the main gravity anomaly sources. In this context, we have developed 2.5-D gravity models of the Serra da Cangalha impact structure for the purpose of investigating geological bodies/structures underneath the crater. Interpretation of the models was supported by ground magnetic data acquired along profiles, as well as by high resolution aeromagnetic data. Ground magnetic data reveal the presence of short-wavelength anomalies probably related to shallow magnetic sources that could have been emplaced during the cratering process. Aeromagnetic data show that the basement underneath the crater occurs at an average depth of about 1.9 km, whereas in the region beneath the central uplift it is raised to 0.51 km below the current surface. These depths are also supported by 2.5-D gravity models showing a gentle relief for the basement beneath the central uplift area. Geophysical data were used to provide further constraints for numeral modeling of crater formation that provided important information on the structural modification that affected the rocks underneath the crater, as well as on shock-induced modifications of target rocks. The results showed that the morphology is consistent with the current observations of the crater and that Serra da Cangalha was formed by a meteorite of approximately 1.4 km diameter striking at 12 km s-1.

Central nervous system of Rhipicephalus sanguineus ticks (Acari: Ixodidae): an ultrastructural study

This study performed the ultrastructural description of the synganglion of Rhipicephalus sanguineus males and females, aiming to contribute to the understanding of the cellular organization of this organ. The results show that the central nervous system of these individuals consists of a mass of fused nerves, named synganglion, from where nerves emerge towards several parts of the body. It is surrounded by the neural lamella, a uniform and acellular layer, constituted by repeated layers of homogeneous and finely granular material. The perineurium is just below, composed of glial cells, which extensions invaginate throughout the nervous tissue. The synganglion is internally divided into an outer cortex, which contains the cellular bodies of the neural cells and an inner neuropile. The neural cells can be classified into two types according to cell size, cytoplasm-nucleus relation, and neurosecretory activity. Type I cells are oval or spherical and present a large nucleus occupying most part of the cytoplasm, which contains few organelles. Type 2 cells are polygonal, present a great cytoplasm volume, and their nuclei are located in the cell periphery. The cytoplasm of these cells contains a well-developed rough endoplasmic reticulum, Golgi regions, mitochondria, and several neurosecretory granules. The subperineurium and the tracheal ramifications are found between the cortex and the neuropile. The latter is formed mainly by neural fibers, tracheal elements, and glial cells. The results obtained show that R. sanguineus males' and females' nervous tissue present an ultrastructural organization similar to the one described in the literature for other tick species.

The dawn of animal skeletogenesis: Ultrastructural analysis of the Ediacaran metazoan Corumbella werneri

Although the basic morphology of the Ediacaran metazoan Corumbella werneri (the type species of the genus) is well established, little is known about its skeletal tissue. Carbonaceous fragments of this fossil from the Itapucumi Group (Paraguay) reveal details of the ultrastructure of its carapace, providing an unprecedented opportunity to understand a paradigmatic issue of the evolution of skeletogenesis in early metazoans. Corumbella was a sessile predator whose carapace consisted of organic polygonal plates with pores and papillae similar to features observed in some conulariids. Its occurrence with the shelly fossil Cloudina suggests that the acquisition of protective structures in metazoans involved penecontemporaneous processes of biomineralization and secretion of organic walls.