In this chapter, we consider the linear radiative transfer model for a passive medium with no intrinsic thermal contributions. The domain is a one-dimensional slab for which reflectivity and transmissivity are determined from the total in- and outgoing radiative fluxes across the boundaries. Further, we assume isotropic scattering in the medium and no emissivity and reflectivity on the boundaries but thermal radiation from the latter and an isotropic incoming radiation from an external source. Our developments are based on the discrete ordinate method in the angular variable and a modified version of the finite volume method in the spatial variable. The solution is obtained by an iterative method, and we present a necessary condition for its convergence based on norm operations.

{The study of sambaquis (ancient shell mounds) in conservation paleobiology is a complicated subject, especially when comparing body sizes of current and past mollusk valves to observe possible changes. There is a lack of information regarding how ancient fisher-gardeners collected these shellfish. Another obstacle is finding the hypothesis tests and data that can be used to compare current and past body sizes. To this end, we use the t-test (tt), Mann-Whitney (mw), and Bootstrap (bt) analyses to determine data scenarios for yellow clam (Amarilladesma mactroides) shells from two sambaquis units, and from two transects along the beaches of Rio Grande do Sul in southern Brazil. The study finds that the average body size of an Amarilladesma mactroides adult specimen is greater in sambaquis than the current valves across all tests (tt

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A pandemia de Covid-19 chegou ao Rio Grande do Sul (RS) evidenciando a necessidade de uma abordagem multidisciplinar e sistemática, buscando respostas emergentes. A falta de uma estratégia nacional de combate ao novo coronavírus exigiu a elaboração de uma alternativa própria por parte do governo estadual. A opção adotada foi um modelo de distanciamento controlado, considerando a gestão do sistema de saúde, visando garantir a capacidade de atendimento dos enfermos por Covid-19 e demais doenças e propiciar o funcionamento dos setores econômicos. O presente artigo faz um apanhado geral da confirmação de casos de Covid-19 no Rio Grande do Sul, analisa a evolução da doença no período de fevereiro a outubro de 2020 e disserta criticamente acerca do modelo de distanciamento controlado aplicado pelo governo do estado. São feitas reflexões sobre os objetivos de tal modelo, que exprimem uma tentativa de condicionamento das práticas espaciais da população, e sobre a eficiência da instrumentalização do controle social simbolizada por cores que indicam a intensidade de restrições.

La pandémie de Covid-19 a atteint le Rio Grande do Sul (RS), soulignant la nécessité d'une approche multidisciplinaire et systématique, à la recherche de réponses émergentes. L'absence d'une stratégie nationale de lutte contre le nouveau coronavirus a nécessité l'élaboration d'une solution de rechange par le gouvernement de l'État. L'option adoptée a été un modèle de distanciation contrôlée, considérant la gestion du système de santé, visant à garantir la capacité de soigner les patients atteints de Covid-19 et d'autres maladies et à permettre le fonctionnement des secteurs économiques. Cet article donne un aperçu de la confirmation des cas de Covid-19 dans l'État de Rio Grande do Sul, analyse l'évolution de la maladie de février à octobre 2020 et discute de manière critique le modèle de distanciation contrôlée appliqué par le gouvernement de l'État. Des réflexions sont menées sur les objectifs de ce modèle, qui expriment une tentative de conditionner les pratiques spatiales de la population, et sur l'efficacité de l'instrumentalisation du contrôle social symbolisé par des couleurs qui indiquent l'intensité des restrictions.

The Covid-19 pandemic reached Rio Grande do Sul (RS), highlighting the need for a multidisciplinary and systematic approach, seeking emerging responses. The lack of a national strategy to combat the new coronavirus required the elaboration of an alternative by the local government. The option adopted was a controlled distance model, considering the health system management, aiming at guaranteeing the capacity to attend the sick due to Covid-19 and other diseases, and allowing the functioning of the economic sectors. This article provides an overview of the confirmation of cases of Covid-19 in Rio Grande do Sul, analyzes the evolution of the disease from February to October 2020, and gives a critical commentary on the controlled distance model applied by the state government. Reflections are made on the objectives of such a model, which express an attempt to condition the population’s spatial practices, and on the efficiency of the instrumentalization of social control symbolized by colors indicating the intensity of restrictions.

The direct carbonate procedure for accelerator mass spectrometry radiocarbon (AMS 14C) dating of submilligram samples of biogenic carbonate without graphitization is becoming widely used in a variety of studies. We compare the results of 153 paired direct carbonate and standard graphite 14C determinations on single specimens of an assortment of biogenic carbonates. A reduced major axis regression shows a strong relationship between direct carbonate and graphite percent Modern Carbon (pMC) values (m = 0.996; 95% CI [0.991–1.001]). An analysis of differences and a 95% confidence interval on pMC values reveals that there is no significant difference between direct carbonate and graphite pMC values for 76% of analyzed specimens, although variation in direct carbonate pMC is underestimated. The difference between the two methods is typically within 2 pMC, with 61% of direct carbonate pMC measurements being higher than their paired graphite counterpart. Of the 36 specimens that did yield significant differences, all but three missed the 95% significance threshold by 1.2 pMC or less. These results show that direct carbonate 14C dating of biogenic carbonates is a cost-effective and efficient complement to standard graphite 14C dating.

The fossil molluscan assemblages found on the shores of Mirim Lake, in southern Brazil and Uruguay, provide information about the environmental changes and geological evolution of that water body. The storm-generated shell deposits at Latinos Spit on the Brazilian shore are dominated by the estuarine bivalve Erodona mactroides, represented mostly by juveniles, and the gastropod Heleobia australis. Species previously unrecorded in this site include the marine gastropods Cylichnella bidentata, Buccinanops cochlidium and Pachycymbiola brasiliana, and the bivalves Tagelus plebeius, Ostrea puelchana, Crassostrea cf. praia, Mactra isabelleana, Anomalocardia flexuosa and Cyrtopleura costata. The two latter currently inhabit tropical areas to the north of Rio Grande do Sul, and their presence in Mirim Lake indicates average coastal water temperatures about 2–3 °C warmer than today. This condition promoted the precipitation of calcium carbonate from dissolved shells, thus cementing together sand and shells in the form of coquinas. The stratigraphic succession, OSL ages obtained in quartz sand from one coquina, radiocarbon dated shells, and δ13C and δ18O of five E. mactroides and five marine species indicate that Mirim Lake became a brackish lagoon around 7.6 ka ago, in response to the postglacial marine transgression (PMT), followed by fully marine conditions during the sea-level highstand of 6–5 ka BP. Marine influence was reduced after ∼4 ka BP as the result of sea-level fall and the closure of the connection with the ocean, related to the evolution of the sandy barrier that originated the modern shoreline. The environmental changes recorded in Mirim Lake help understand how coastal lagoons and their associated ecosystems respond to sea-level oscillations, which may be relevant to address future responses of these water bodies to the ongoing climate change.