Be-and Emerald Deposits of the Central Urals (Russia): Conditions of Formation

The Be- and emerald deposits of the Emerald Mines region, in the central part of the Upper-Paleozoic Uralian orogen (Russia), are related to a major shear zone of N-S direction, where both Be-rich S-type granitoids (Carboniferous to Permian) and Cr-rich rocks (ophiolitic dunites and peridotes, Silurian to Devonian) are present.

Kinetics of formation of hypoxanthine containing base pairs by HIV-RT: RNA template effects on the base substitution frequencies

Hypoxanthine (H), the deamination product of adenine, has been implicated in the high frequency of A to G transitions observed in retroviral and other RNA genomes. Although H·C base pairs are thermodynamically more stable than other H·N pairs, polymerase selection may be determined in part by kinetic factors. Therefore, the hypoxanthine induced substitution pattern resulting from replication by viral polymerases may be more complex than that predicted from thermodynamics. We have examined the steady-state kinetics of formation of base pairs opposite template H in RNA by HIV-RT, and for the incorporation of dITP during first- and second-strand synthesis. Hypoxanthine in an RNA template enhances the k2app for pairing with standard dNTPs by factors of 10–1000 relative to adenine at the same sequence position. The order of base pairing preferences for H in RNA was observed to be H·C >> H·T > H·A > H·G. Steady-state kinetics of insertion for all possible mispairs formed with dITP were examined on RNA and DNA templates of identical sequence. Insertion of dITP opposite all bases occurs 2–20 times more frequently on RNA templates. This bias for higher insertion frequencies on RNA relative to DNA templates is also observed for formation of mispairs at template A. This kinetic advantage afforded by RNA templates for mismatches and pairing involving H suggests a higher induction of mutations at adenines during first-strand synthesis by HIV-RT.

Isotope characterization and estimated temperature of formation of calcite veins in ODP Sites 124-768 and 124-770 (Table 1)

Secondary carbonate minerals were recovered within the basalts at both ODP Sites 768 and 770 in the Sulu and Celebes seas. Petrographic and X-ray diffraction analyses indicate that the carbonates are calcites. Other alteration products recognized in the thin sections are smectites, iron oxides, and gypsum. The 13C values of carbonates from both sites range from 1.6 per mil to 2.3 per mil, which are indicative of inorganic carbonate formation with no contributions from 13C-depleted sources such as oxidized organic carbon or methane. The oxygen isotopes at Site 770 range from 30.8 per mil to 31.6 per mil, which indicates a pervasive circulation of cold seawater (9° to 12°C) during alteration of the Celebes Sea basalts. In contrast, carbonates associated with Site 768 basalts have less positive d18O values (21.0 per mil to 27.3 per mil). A lighter 18O isotopic signature indicates the formation of secondary calcite at either higher temperatures or in a system closed to seawater. The rapidly deposited pyroclastic flows at Site 768 would have limited water access to the crust very soon after its formation, which leads us to speculate that the carbonates in the Sulu Sea basalts were formed by isotopically modified fluids resulting from basalt alteration in a closed system.

A complete analysis or grammar of the German language: being a philological view, both theoretical and practical, of its construction, analogies, and various properties ...

Mode of access: Internet.

The total and free energies of formation of the oxides of thirty-two metals,

Bibliographical foot-notes.

Comparative studies of hyperhomodesmotic reactions for the calculation of standard heats of formation of fullerenes

How can the accuracy of the calculated standard heats of formation Delta H-f(0) of fullerenes be improved? How reliable are the values of Delta H-f(0) calculated from hyperhomodesmotic reactions? This work is the first to address these questions. By comparing the results obtained from three hyperhomodesmotic reactions containing only fullerenes, it is illustrated that both the resonance contribution and the strain energy contribution should be considered in the construction of hyperhomodesmotic reactions. An attempt to construct such hyperhomodesmotic reactions for fullerenes has been carried out, and several new insights are indicated.

Exploring oxidative modifications of tyrosine:an update on mechanisms of formation, advances in analysis and biological consequences

Protein oxidation is increasingly recognised as an important modulator of biochemical pathways controlling both physiological and pathological processes. While much attention has focused on cysteine modifications in reversible redox signalling, there is increasing evidence that other protein residues are oxidised in vivo with impact on cellular homeostasis and redox signalling pathways. A notable example is tyrosine, which can undergo a number of oxidative post-translational modifications to form 3-hydroxy-tyrosine, tyrosine crosslinks, 3-nitrotyrosine and halogenated tyrosine, with different effects on cellular functions. Tyrosine oxidation has been studied extensively in vitro, and this has generated detailed information about the molecular mechanisms that may occur in vivo. An important aspect of studying tyrosine oxidation both in vitro and in biological systems is the ability to monitor the formation of oxidised derivatives, which depends on a variety of analytical techniques. While antibody-dependent techniques such as ELISAs are commonly used, these have limitations, and more specific assays based on spectroscopic or spectrometric techniques are required to provide information on the exact residues modified and the nature of the modification. These approaches have helped understanding of the consequences of tyrosine oxidation in biological systems, especially its effects on cell signalling and cell dysfunction, linking to roles in disease. There is mounting evidence that tyrosine oxidation processes are important in vivo and can contribute to cellular pathology.

On the temperature dependence of the rate coefficient of formation of C2+ from C + CH+

[EN] We carry out quasi-classical trajectory caculations for theC + CH+ → C2+ + H reaction on an ad hoc computed high-level ab initio potential energy surface. Thermal rate coefficients at the temperatures of relevance in cold interstellar clouds are derived and compared with the assumed, temperature-independent estimates publicly available in kinetic databases KIDA and UDfA. For a temperature of 10 K the database value overestimates by a factor of two the one obtained by us (thus improperly enhancing the destruction route of CH+ in astrochemical kinetic models) which is seen to double in the temperature range 5–300 K with a sharp increase in the first 50 K. The computed values are fitted via the popular Arrhenius–Kooij formula and best-fitting parameters α = 1:32 X 10-9 cm3s-1, β = 0:10 and γ = 2:19 K to be included in the online mentioned databases are provided. Further investigation shows that the temperature dependence of the thermal rate coefficient better conforms to the recently proposed so-called ‘deformed Arrhenius’ law by Aquilanti and Mundim.

Futebol de base e produção de subjetividade: o psicólogo do esporte e a construção do atleta contemporâneo

A proposta deste estudo foi construir uma cartografia dos modos de fazer psicologia em centros de treinamento (CTs) de categorias de base, bem como das relações da psicologia do esporte com outros saberes/poderes e de seus possíveis efeitos na formação do jogador de futebol, tendo por campo empírico o cotidiano de alguns clubes de Belo Horizonte e do Rio de Janeiro. Em aliança com os pensamentos de Félix Guattari e Gilles Deleuze, apropriamo-nos dos escritos destes e de outros pesquisadores da Análise Institucional como interlocutores nesta cartografia; igualmente, das contribuições de Michel Foucault sobre sociedade disciplinar e biopoder. Estudos antropológicos e sócio-históricos também nos ajudaram a compreender como se constrói a noção/prática de formação no futebol brasileiro contemporâneo. Colaboraram ainda nessa composição os debates metodológico-epistemológicos sobre História Oral, procedimento que funcionou como um dispositivo ético-político durante todo o processo de investigação. Neste sentido, mediante entrevistas de história oral temática, buscou-se conhecer o trabalho de quatro psicólogos do esporte atuantes em categorias de base na atualidade. Complementarmente, observações em centros de treinamento foram realizadas. Nesse percurso, apreendemos nuances da instrumentalização do corpo-atleta que remetem ao processo histórico de construção dos atuais modos de formação do jogador de futebol no Brasil. Pistas sobre os primeiros trabalhos de Psicologia do Esporte de que se tem notícia integram tal processo, e apontam a uma psicologia que também se instrumentalizava, tendo os testes psicométricos como principal recurso. Em uma trajetória na qual forças mais, e menos flexíveis produzem efeitos políticos, vê-se o aspirante a jogador de futebol transformar-se em um atleta que funciona como jogador-peça, jogador-produto, ou mesmo jogador-empresa, a fim de realizar o almejado e muitas vezes inquestionável sonho de ser mundialmente conhecido e aclamado. No espaço dos CTs, disciplina e biopoder se articulam em dispositivos em prol da manutenção de uma produção em moldes capitalísticos. Das modulações das práticas neoliberais surge ainda a figura do empresário para gerenciar a vida dos jogadores e garantir que sejam produtos valorizados no mercado global de boleiros. Embora ainda hoje os testes e os perfis psicológicos sejam instrumentos hegemônicos na psicologia esportiva, as práticas desta última são tão diversas quanto os modos de subjetivação existentes e implicam efeitos às vezes mais, às vezes menos adaptados à promoção do rendimento esportivo e à constituição do atleta empreendedor-de-si mesmo.

Las prácticas de la enseñanza en la Educación Superior : Reflexiones pedagógico-didácticas sobre los usos de las tecnologías informáticas en las aulas

El presente trabajo da cuenta de una investigación llevada a cabo entre mediados y fines de los años `90 como parte de la acreditación académica del grado de Licenciatura en Ciencias de la Educación. La misma aborda como tema de estudio el campo de la Educación Superior y las Tecnologías Informáticas, particularmente el uso pedagógico-didáctico que se hace de dichas tecnologías a partir de su introducción en las prácticas de enseñanza. Metodológicamente se trabajó en dos etapas con de estilos de indagación diferenciados, pero a la vez imbricados. La primera consistió en recoger la mirada institucional respecto a la introducción de dichas tecnologías. A tales efectos, se seleccionó como población del estudio a miembros responsables de la conducción institucional de algunas de las Unidades Académicas de la Universidad Nacional de La Plata e Institutos Superiores de Formación Docentes -públicos y privados- de la provincia de Bs. As. Mientras que la segunda etapa se configuró a partir de los hallazgos de la anterior dando lugar a la necesidad de profundizar, mediante un estudio de casos, en el análisis de prácticas de enseñanza en las que se produce la inclusión de las tecnologías informáticas. Intentando visualizar en ellas, no sólo, la introducción de un artefacto novedoso sino la presencia de elementos de una cultura de innovación educativa que den cuenta de procesos de reflexión y de cambio en dichas prácticas. Las conclusiones arribadas posibilitaron integrar la dimensión institucional con la dimensión áulica; conocer prácticas de enseñanza que intentan, desde su espacio de trabajo, modificar la estructura de clase tradicional, acercando a los alumnos otras posibilidades de acceso al conocimiento y vislumbrar, en forma incipiente y en función de las posibilidades profesionales y personales de cada profesor, niveles de reflexión de su propia práctica con el propósito de mejorarlas.