Corals not serpulids: mineralized colonial fossils in the Lower Jurassic marginal facies of South Wales

Poorly preserved colonial corals occur near the base of the Lower Jurassic marginal facies at Southerndown, South Wales. Previously they have been interpreted as serpulid colonies, despite a dissimilarity to any serpulids known from elsewhere in the Lias or the few known extant colonial serpulids. However, local preservation of fine detail reveals evidence, in the form of corallites, septa and tabulae, that they are scleractinian corals of the Suborder Faviina, Family Stylophyllidae. These coral specimens occur in close association with barite–galena veins in the underlying Carboniferous Limestone and adjacent Lias marginal facies. Their widespread misindentification as ‘serpulid reefs’ is a consequence of coarse replacive mineralization by barite, which has largely obscured the diagnostic characters

Galaxies in box: A simulated view of the interstellar medium

We review progress in the development of physically realistic three dimensional simulated models of the galaxy.We consider the scales from star forming molecular clouds to the full spiral disc. Models are computed using hydrodynamic (HD) or magnetohydrodynamic (MHD) equations and may include cosmic ray or tracer particles. The range of dynamical scales between the full galaxy structure and the turbulent scales of supernova (SN) explosions and even cloud collapse to form stars, make it impossible with current computing tools and resources to resolve all of these in one model. We therefore consider a hierarchy of models and how they can be related to enhance our understanding of the complete galaxy.Comment: Chapter in Large Scale Magnetic Fields in the Univers

Self-avoiding fractional Brownian motion - The Edwards model

In this work we extend Varadhan's construction of the Edwards polymer model to the case of fractional Brownian motions in $\R^d$, for any dimension $d\geq 2$, with arbitrary Hurst parameters $H\leq 1/d$.Comment: 14 page

Complementarity of information sent via different bases

We discuss quantitatively the complementarity of information transmitted by a quantum system prepared in a basis state in one out of several different mutually unbiased bases (MUBs). We obtain upper bounds on the information available to a receiver who has no knowledge of which MUB was chosen by the sender. These upper bounds imply a complementarity of information encoded via different MUBs and ultimately ensure the security in quantum key distribution protocols.Comment: 9 pages, references adde

Arbitrary rotation and entanglement of flux SQUID qubits

We propose a new approach for the arbitrary rotation of a three-level SQUID qubit and describe a new strategy for the creation of coherence transfer and entangled states between two three-level SQUID qubits. The former is succeeded by exploring the coupled-uncoupled states of the system when irradiated with two microwave pulses, and the latter is succeeded by placing the SQUID qubits into a microwave cavity and used adiabatic passage methods for their manipulation.Comment: Accepted for publication in Phys. Rev.

General boundary conditions for the envelope function in multiband k.p model

We have derived general boundary conditions (BC) for the multiband envelope functions (which do not contain spurious solutions) in semiconductor heterostructures with abrupt heterointerfaces. These BC require the conservation of the probability flux density normal to the interface and guarantee that the multiband Hamiltonian be self--adjoint. The BC are energy independent and are characteristic properties of the interface. Calculations have been performed of the effect of the general BC on the electron energy levels in a potential well with infinite potential barriers using a coupled two band model. The connection with other approaches to determining BC for the envelope function and to the spurious solution problem in the multiband k.p model are discussed.Comment: 15 pages, 2 figures; to be published in Phys. Rev. B 65, March 15 issue 200

Expansão da agricultura orgânica e os desafios enfrentados por produtores brasileiros na produção e exportação de orgânicos

A agricultura orgânica baseia-se no uso de métodos de cultivos ecológicos, alternativos à agricultura convencional, com o intuito de preservar o meio ambiente. A expansão do mercado mundial de produtos orgânicos decorreu da preocupação com a degradação ambiental e com a segurança do alimento. Entretanto, os produtores orgânicos brasileiros enfrentam desafios tanto no processo produtivo quanto para acessarem o mercado internacional orgânico. Neste contexto, o objetivo deste estudo foi analisar a evolução da produção orgânica e os desafios para produção e exportação dos produtos orgânicos brasileiros, particularmente para o mercado europeu. Para analisar a evolução da produção orgânica foram coletados dados do Instituto Brasileiro de Geografia e Estatística (IBGE), Ministério da Agricultura, Pecuária e Abastecimento (MAPA) e Research Institute of Organic Agriculture (FiBL) sobre a área agropecuária, número de estabelecimentos e de produtores, vendas no varejo, consumo per capita e exportações. Os dados disponíveis mostraram o crescimento contínuo da produção orgânica mundial entre 2000 e 2018. A análise do comércio mundial de orgânicos foi realizada por meio do Modelo Gravitacional. A equação gravitacional estimada utilizou como variável dependente as exportações mundiais de orgânicos. Já as variáveis independentes foram: o Produto Interno Bruto (PIB) e a população dos países exportadores de orgânicos, o PIB e a população da América do Norte e União Europeia, além da área agrícola destinada à produção orgânica tanto dos países exportadores quanto da América do Norte e União Europeia. De acordo com o resultado do modelo, as variáveis determinantes das exportações de orgânicos foram o PIB dos países exportadores, bem como o PIB, a população e a área agrícola orgânica da América do Norte e da União Europeia. Além disso, também foram realizadas entrevistas com agricultores familiares orgânicos brasileiros a fim de investigar os desafios que estes produtores tem encontrado na produção e comercialização de orgânicos. Eles responderam questões relacionadas à produção de orgânicos, aos desafios enfrentados, à importância das políticas públicas para o setor, à certificação e ao acesso ao mercado europeu. Em relação às dificuldades na produção, mencionaram fatores como alto custo e burocracia da certificação, falta de pagamento diferenciado pelo produto orgânico e indisponibilidade de insumos orgânicos. Já em relação aos desafios para exportação para o mercado orgânico europeu, relataram problemas como a falta de conhecimento do processo de exportação, dificuldade na obtenção da certificação orgânica europeia, falta de conhecimento da legislação orgânica europeia e do mercado europeu, bem como a escala de produção para exportação. Os produtores entrevistados consideram as políticas públicas importantes para o desenvolvimento da agricultura orgânica no Brasil, mas que necessitam ser aprimoradas para atender as necessidades dos produtores familiares orgânicos

Complement Split Product C5a Mediates the Lipopolysaccharide‐Induced Mobilization of Cfu‐S and Haemopoietic Progenitor Cells, But Not the Mobilization Induced By Proteolytic Enzymes

Abstract. Intravenous (i.v.) injection of mice with lipopolysaccharide (LPS), and the proteolytic enzymes trypsin and proteinase, mobilizes pluripotent haemopoietic stem cells (CFU‐s) as well as granulocyte‐macrophage progenitor cells (GM‐CFU) and the early progenitors of the erythroid lineage (E‐BFU) from the haemopoietic tissues into the peripheral blood. We investigated the involvement of the complement (C) system in this process. It appeared that the early mobilization induced by LPS and other activators of the alternative complement pathway, such as Listeria monocytogenes (Lm) and zymosan, but not that induced by the proteolytic enzymes, was absent in C5‐deficient mice. the mobilization by C activators in these mice could be restored by injection of C5‐sufficient serum, suggesting a critical role for C5. The manner in which C5 was involved in the C activation‐mediated stem cell mobilization was studied using a serum transfer system. C5‐sufficient serum, activated in vitro by incubation with Lm and subsequently liberated from the bacteria, caused mobilization in both C5‐sufficient and C5‐deficient mice. C5‐deficient serum was not able to do so. the resistance of the mobilizing principle to heat treatment (56°C, 30 min) strongly suggests that it is identical with the C5 split product C5a, or an in vivo derivative of C5a. This conclusion was reinforced by the observation that a single injection of purified rat C5a into C5‐deficient mice also induced mobilization of CFU‐s. Copyrigh