Carbon-isotope stratigraphy and ammonite faunal turnover for the Middle Jurassic in the Southern Iberian palaeomargin

Variations in the stable carbon-isotope ratio of marine and continental sediments can reflect changes in sink and flux modifications of the palaeocarbon cycle. Here we report carbon-isotope compositions of Middle Jurassic marine carbonates from the Betic Cordillera (southern Spain), which represents an ideal region to link the stable carbon-isotope curves directly to ammonite zones and subzones, and thereby for the first time achieve an accurate chronostratigraphic calibration. The five sections studied represent basin and high swell deposits of the Southern Iberian palaeomargin. We find a similar delta C-13 of carbonates between different oceanic areas, suggesting a homogeneous carbon-isotope oceanic reservoir through the Middle Jurassic. The Aalenian-Bajocian transition is a critical period in ammonite evolution; hence the Early Jurassic fauna are replaced by new ammonite families which become dominant throughout the Middle and Late Jurassic. For this reason, we compared the delta C-13 values of carbonates with ammonite diversity and extinction rates at different taxonomical levels in order to explore the possible relationship between the carbon cycle and ammonite evolution. The carbon-isotope values of carbonates are not exactly linearly correlated with the extinction rate and ammonite diversity, but the main faunal turnovers follow minimum delta C-13 values, where extinct taxa are replaced by new ones. Likewise, radiation episodes are associated with increasing delta C-13 values and with transgressive sea-level rise. All these data support the idea that perturbations in the global carbon cycle reflect rapid palaeoenvironmental changes. We made detailed analyses of these faunal turnovers, using them as a proxy to identify major palaeoenvironmental crises in their ecosystems forced by modification in the carbon cycle. (c) 2006 Elsevier B.V All rights reserved.

Organic geochemistry across the Permian-Triassic transition at the Idrijca Valley, Western Slovenia

Bulk and molecular stable C isotopic compositions and biomarker distributions provide evidence for a diverse community of algal and bacterial organisms in the sedimentary organic matter of a carbonate section throughout the Permian-Triassic (P/Tr) transition at the Idrijca Valley, Western Slovenia. The input of algae and bacteria in all the Upper Permian and Lower Scythian samples is represented by the predominance of C-15-C-22 n-alkanes, odd C-number alkylcyclohexanes, C-27 steranes and substantial contents Of C-21-C-30 acyclic isoprenoids. The occurrence of odd long-chain n-alkanes (C-22-C-30) and C29 steranes in all the samples indicate a contribution of continental material. The decrease of C-org and C-carb contents, increase of Rock-Eval oxygen indices, and C-13-enrichment of the kerogen suggest a decrease in anoxia of the uppermost Permian bottom water. The predominance of odd C-number alkylcycloalkanes, C-27 steranes, and C-17 n-alkanes with delta(13)C values similar to-30parts per thousand, and C-13-enrichment of the kerogens in the lowermost Scythian samples are evidence of greater algal productivity. This increased productivity was probably sustained by a high nutrient availability and changes of dissolved CO2 speciation associated to the earliest Triassic transgression. A decrease Of Corg content in the uppermost Scythian samples, associated to a C-13-depletetion in the carbonates (up to 4parts per thousand) and individual n-alkanes (up to 3.4parts per thousand) compared to the Upper Permian samples, indicate lowering of the primary productivity (algae, cyanobacteria) and/or higher degradation of the organic matter. (C) 2003 Elsevier Ltd. All rights reserved.

Basin-internal derivation of hydrocarbons in the Witwatersrand Basin, South Africa: evidence from bulk and molecular δ13C data

Gold in the quartz-pebble conglomerates of the late Archean Witwatersrand Basin, South Africa, is often intimately associated with carbonaceous matter of organic/biogenic origin which occurs in the form of stratiform carbon seams and paragenetically late bitumen nodules. Both carbon forms are believed to be formed by solidification of migrating hydrocarbons. This paper presents bulk and molecular chemical and stable carbon isotope data for the carbonaceous matter, all of which are used to provide a clue to the source of the hydrocarbons. These data are compared with those from intra-basinal shales and overlying dolostone of the Transvaal Supergroup. The delta C-13 values of the extracts from the Witwatersrand carbonaceous material show small differences (up to 2.4 parts per thousand) compared to the associated insoluble organic matter. This suggests that the auriferous rocks were stained by mobile hydrocarbons produced by thermal and oxidative alteration of indigenous bitumens, a contribution from hydrocarbons derived from intra-basinal Witwatersrand shales cannot be excluded. Individual aliphatic hydrocarbons of the various carbonaceous materials were subjected to compound specific isotope analysis using on-line gas chromatography/combustion/stable isotope ratio mass spectrometry (GC/C/IRMS). The limited variability of the molecular parameters and uniform delta C-13 values of individual n-alkanes (-31.1 +/- 1.7 parts per thousand) and isoprenoids (-30.7 +/- 1.1 parts per thousand) in the Witwatersrand samples exclude the mixing of oils from different sources. Carbonaceous matter in the dolostones shows distinctly different bulk and molecular isotope characteristics and thus cannot have been the source of the hydrocarbons in the Witwatersrand deposits. All the various forms of Witwatersrand carbon appear indigenous to the Witwatersrand Basin, and the differences between them are explained by variable, in general probably short (centimeter- to meter-scale) hydrocarbon migration during diagenesis and subsequent hydrothermal infiltration. (C) 2001 Elsevier Science B.V. All rights reserved.

Comportamento da laranjera 'Folha Murcha' em sete porta-enxertos no noroeste do Paraná

Este trabalho avaliou por um período de 14 anos, em Paranavaí-PR, o comportamento de plantas de laranjeira 'Folha Murcha' enxertadas nos porta-enxertos: limoeiros 'Cravo' (Citrus limonia), 'Rugoso da África' (Citrus jambhiri) e 'Volkameriano' (Citrus volkameriana), citrangeiro 'C-13' (Citrus sinensis x Poncirus trifoliata), trifoliata (Poncirus trifoliata), tangerineiras 'Sunki' (Citrus sunki) e 'Cleópatra' (Citrus reshni). O delineamento experimental utilizado foi o de blocos ao acaso, com sete tratamentos (porta-enxertos) e quatro repetições, com três plantas por parcela. Os volumes das copas de plantas em tangerineira 'Cleópatra' e limoeiro 'Rugoso da África' foram significativamente maiores. Plantas em limoeiro 'Cravo' apresentaram a menor diferença entre os diâmetros dos troncos do porta-enxerto e da copa. A produção acumulada foi superior nas plantas em limoeiro 'Rugoso da África' e tangerineira 'Cleópatra' e menor em plantas sobre o trifoliata. A alternância da produção não foi acentuada nas plantas sobre os porta-enxertos avaliados. O teor de sólidos solúveis totais foi significativamente superior nos frutos obtidos de plantas enxertadas em trifoliata e menor em limoeiro 'Rugoso da África'. A qualidade do suco apresentou-se dentro dos padrões aceitáveis para variedades-copa de laranjeiras. A tangerineira 'Cleópatra' e o limoeiro 'Rugoso da África' são porta-enxertos promissores para a laranjeira 'Folha Murcha' nas condições avaliadas.

Efeito da substituição por átomos de flúor no equilíbrio conformacional de chalcona

Chalcone (1) and its fluorinated derivatives 2-4, as well as their cyclic analogues 5-10, were synthesized through an aldol condensation reaction between the corresponding ketone and aldehyde. These compounds were characterized by IR, EIMS and ¹H and 13C NMR spectral data. Modern NMR techniques allowed us to conclude that the compounds obtained show E configuration. These techniques were also employed to investigate the equilibrium involving the s-cis and s-trans conformations of 1-4, with this equilibrium being dependent on the fluorine substitution on both aromatic rings, A or B. IR studies indicated that the yield of the s-cis conformation in the fluorinated derivatives is 57.4±1.4; 88.1±0.4 and 66.4±0.7%, for 2, 3 and 4, respectively, based on previous ¹H NMR calculations for chalcone. Theoretical calculations, using the MMX method, were employed to justify the variation of chemical shifts for the fluorinated derivatives and cyclic analogues. These chemical shifts are consequence of the anisotropic effect showed by the carbonyl group on these compounds.

Relation of the disaccharidases in the small intestine of the rat to the degree of experimentally induced iron-deficiency anemia

Hypolactasia associated with severe iron-deficiency anemia has been reported in several studies. The objective of the present study was to determine whether hypolactasia is associated with the degree and duration of iron-deficiency anemia. Newly weaned male Wistar rats were divided into a control group receiving a diet supplemented with iron (C) and an experimental group (E) receiving a diet not supplemented with iron (iron-deficiency diet). The animals were studied on the 3rd, 5th, 7th, 14th, 21st, 28th and 35th days of the experiment, when overall and iron nutritional status and disaccharidase activity in the small intestine were determined by the Dahlqvist method. A reduction in weight occurred in the anemic animals starting on the 5th day of the study. Anemia was present in the experimental animals, with a progressive worsening up to the 14th day (hemoglobin: C = 13.27 and E = 5.37) and stabilizing thereafter. Saccharase and maltase activities did not differ significantly between groups, whereas lactase showed a significant reduction in total (TA) and specific activity (SA) in the anemic animals starting on the 21st day of the study. Median lactase TA for the C and E groups was 2.27 and 1.25 U on the 21st day, 2.87 and 1.88 U on the 28th day, and 4.20 and 1.59 U on the 35th day, respectively. Median lactase SA was 0.31 and 0.20 U/g wet weight on the 21st day, 0.39 and 0.24 U/g wet weight on the 28th day, and 0.42 and 0.23 U/g wet weight on the 35th day, respectively. These findings suggest a relationship between the enzymatic alterations observed and both the degree and duration of the anemic process. Analysis of other studies on intestinal disaccharidases in anemia suggests that the mechanism of these changes may be functional, i.e., that the enterocytes may suffer a reduction in their ability to synthesize these enzymes.

Collection de pièces de théâtre. TOME II

Contient : 1 "Antes a filha que o vinho. Farça." ; 2 "A apotheose de Hercules. Drama em trez actos. Lisboa, 1806." ; 3 "Drama em hum só acto, que se intitula : A appariçaõ a Affonso Henriques no campo de Ourique, representado no theatro nacional do Salitre, no mes de março (na quaresma) de 1813." ; 4 "A quanto obriga amor ou Os doidos da data moderna. Entremez." ; 5 "Drama intitulado : Argonauta escravo." ; 6 "Comedia emtitulada : Armida e Reinaldo, em dous actos." ; 7 "Opera. Os asombros da constancia : Volugeso e Berenice. Copiada aos 20 de novembro de 1788." ; 8 et 9 "A assembleia rafada ou A velha taful. Farça composta por hum anonimo, ampliada por Alexandre José Victor da Costa Sequeira, copiada aos 29 de novembro de 1817." Deux exemplaires, dont un non daté et sans le nom de l'arrangeur ; 10 "As astucias de Zanguizarra ou Os velhos logrados. Farça que se repprezentou no theatro nacional da rua dos Condes, com geral aceitaçaõ, composta pelo ponto Ricardo Jozé Fortuna, copiada aos 20 de abril de 1818." ; 11 "A audiencia ou A eschola dos principes, drama sentimental de trez actos, que se repprezentou no theatro nacional da rua dos Condes, com geral aceitaçaõ, composto pelo actor Antonio Jozé de Paula, copiado aos 20 de setembro de 1817." ; 12 "O aventureiro nocturno. Drama em 3 actos. Anno de 1814. Por A. R. C." ; 13 "O aviso á gazeta. Farça."

Palladium and platinum complexes of vitamin Bâ

Palladium and platinum complexes of pyridoxamine, pyridoxine and pyridoxal have been prepared. The structures of the complexes PtCI2PM.H20, trans-PdC12 (PN)2 and [PLH+ ]2[PtC16] 2- ,H20 have been determined by use of single crystal x-ray studies. The compounds PdC12PH, trans-PdC12 (PN) 2 , cis-PdCI2 (PN)2 and cis PdC12 (PL)2 were also studied by use of carbon-13 nmr spectroscopy. All the complexes have also been characterised by use of infrared spectral studies. In the complexes, PtCI2PM.H20 and PdC12PM, the ligand pyridoxamine is chela ted to the metal through the aminomethyl nitrogen and the phenolate oxygen atoms whereas in the complexes, trans-PdCI2 (PN)2' cis-PdCI2 (PN)2 and cis-PdC12 (PL)2 the vitamin B6 ligands are coordinated to the metal through the pyridine ring nitrogen. The compounds [PLH+ ]2[PtCI6] 2- .H20 and [PMH2] 2+ [PdCI4] 2- .H20have no direct metal-ligand bonding, In all the complexes, the metal maintains a square planar coordination except in [PLH +] 2[PtCI6] 2- ,H20 where the metal is octahedrally coordinated. PH pyridoxamine [PMH ] 2+ = diprotonated pyridoxamine 2 PN = pyridoxine PL pyridoxal PLH+ protonated pyridoxal

Chemoenzymatic Total Synthesis of Morphine alkaloids: Synthesis of Dihydrocodeine and Hydrocodone via a Double Claisen Strategy and ent-Hydromorphone via an Oxidative Dearomatization/intramolecular [4+2] Cycloaddition

This thesis describes the chemoenzymatic synthesis of three morphine alkaloids. The total synthesis of dihydrocodeine and hydrocodone was accomplished starting from bromobenzene in 16 and 17 steps, respectively. The key steps included a microbial oxidation of bromobenzene by E. coli JM109 (pDTG601A), a Kazmaier-Claisen rearrangement of glycinate ester to generate C-9 and C-14 stereo centers, a Johnson-Claisen rearrangement to set the C-13 quaternary center, and a C-10/C-11 ring closure via a Friedel-Crafts reaction. In addition, the total synthesis of ent-hydromorphone starting from β-bromoethylbenzene in 12 steps is also described. The key reactions included the enzymatic dihydroxylation of β-bromoethylbenzene to the corresponding cis-cyclohexadienediol, a Mitsunobu reaction, and an oxidative dearomatization followed by an intramolecular [4+2] cycloaddition.

sassen, saskia – crítica e interpretación

El presente proyecto es una idea que trata de mirar principalmente que hace competitiva a un país, cuales son los pasos, que se requiere y que entes y personas deben estar relacionados con el proyecto para lograrlo. Es necesario mirar el caso de varios países y ciudades para saber cómo pasaron de ser entes territoriales comunes y corrientes para convertirse en naciones con buen desarrollo y buenas expectativas de vida. Para esto se tiene que relacionar un concepto clave que ayuda a entender la competitividad de lospaíses y es la productividad territorial. A parte resaltar una autora, SaskiaSassen, que habla de ciudades tan competitivas que llegaron a ser ciudades globales. La idea del trabajo es llegar a unas estrategias específicas que ayuden a un ente territorial a ser más competitivo y productivo tomando como base países y ciudades que ya lo han implementado. Al final lograr destacar estrategias y dar recomendaciones de cómo el estado colombiano, el sector privado y la sociedad pueden impulsar, intervenir, aumentar e innovar para obtener una competitividad y productividad importante para el país.

Programas de entrenamiento en análisis y modificación de conducta para padres, profesores de EGB y especialistas en Pedagogía terapeútica.

Ofrecer una pauta de pensamiento y acción que permita resolver operativamente algunos problemas planteados por la instrucción a padres y educadores dentro del marco de la Psicología de la modificación de conducta. Crear manuales que sirvan al psicólogo y/o pedagogo para poder llevar adelante cursos de modificación de conducta para educadores y padres. Para el curso de educadores y especialistas se utilizaron 4 muestras: a) 10 educadores de EGB especialistas en activo de Pedagogía terapéutica; b) 9 educadores de EGB con la misma titulación; c) 13 educadores de EGB (la mayoría directores); d) 8 educadores de EGB. La muestra del curso de padres la constituyen los oyentes del programa de radio. El informe final incluye una revisión histórica y bibliográfica de la (reciente) Psicología de la modificación de la conducta que fundamentalmente resalta su demostrada eficacia en la resolución de problemas educativos. Posteriormente describe los cursos realizados (para profesores de EGB y especialistas en Pedagogía terapéutica por un lado, y para padres a través de la radio, por otro) y los evalúa. La evaluación de los cursos se lleva a cabo a través de variados criterios incluyendo 2 estudios de casos: 1) Efectos de la observación de fichas en una clase de deficientes mentales, y cambio de precio en un sistema de Economía. 2) Modelamiento comportamental en un caso de oligofrenia profunda con base orgánica. Cuestionario de preguntas a cumplimentar por los asistentes al curso de educadores después de cada sesión. Cuestionario de evaluación del curso. Correspondencia de los oyentes. Porcentajes. Estudios de casos. Puesta a punto de unos esquemas sobre un texto básico en modificación de conducta en ambientes educativos para profesores de EGB y especializados en Pedagogía terapéutica. Realización de cursos -formulación de un primer texto-guía, las sesiones de los cursos deberán ser espaciadas, sería aconsejable 20 por curso -, realizada la experiencia utilizando los mass media (la radio) se hace patente la necesidad de depurar su duración y aligerar su contenido para el entorno social canario. La modificación de conducta ofrece grandes posibilidades de aplicación en los ámbitos educativos. Es factible la realización de cursos encaminados a ofrecer una información útil en modificación de conducta para padres y profesores. Resulta claro que se pueden utilizar los medios de comunicación social para establecer contacto con los padres, con el fin de poder perfilar programas de acción comunitaria.

Nuclear magnetic resonance chemical shifts with the statistical average of orbital-dependent model potentials in Kohn-Sham density functional theory

The performance of the SAOP potential for the calculation of NMR chemical shifts was evaluated. SAOP results show considerable improvement with respect to previous potentials, like VWN or BP86, at least for the carbon, nitrogen, oxygen, and fluorine chemical shifts. Furthermore, a few NMR calculations carried out on third period atoms (S, P, and Cl) improved when using the SAOP potential

Simulating SOC changes in 11 land use change chronosequences from the Brazilian Amazon with RothC and Century models

Land use and land cover changes in the Brazilian Amazon have major implications for regional and global carbon (C) cycling. Cattle pasture represents the largest single use (about 70%) of this once-forested land in most of the region. The main objective of this study was to evaluate the accuracy of the RothC and Century models at estimating soil organic C (SOC) changes under forest-to-pasture conditions in the Brazilian Amazon. We used data from 11 site-specific 'forest to pasture' chronosequences with the Century Ecosystem Model (Century 4.0) and the Rothamsted C Model (RothC 26.3). The models predicted that forest clearance and conversion to well managed pasture would cause an initial decline in soil C stocks (0-20 cm depth), followed in the majority of cases by a slow rise to levels exceeding those under native forest. One exception to this pattern was a chronosequence in Suia-Missu, which is under degraded pasture. In three other chronosequences the recovery of soil C under pasture appeared to be only to about the same level as under the previous forest. Statistical tests were applied to determine levels of agreement between simulated SOC stocks and observed stocks for all the sites within the 11 chronosequences. The models also provided reasonable estimates (coefficient of correlation = 0.8) of the microbial biomass C in the 0-10 cm soil layer for three chronosequences, when compared with available measured data. The Century model adequately predicted the magnitude and the overall trend in delta C-13 for the six chronosequences where measured 813 C data were available. This study gave independent tests of model performance, as no adjustments were made to the models to generate outputs. Our results suggest that modelling techniques can be successfully used for monitoring soil C stocks and changes, allowing both the identification of current patterns in the soil and the projection of future conditions. Results were used and discussed not only to evaluate soil C dynamics but also to indicate soil C sequestration opportunities for the Brazilian Amazon region. Moreover, modelling studies in these 'forest to pasture' systems have important applications, for example, the calculation of CO, emissions from land use change in national greenhouse gas inventories. (0 2007 Elsevier B.V. All rights reserved.

Floodplain environmental change during the Younger Dryas and Holocene in Northwest Europe: Insights from the lower Kennet Valley, south central England

Many lowland rivers across northwest Europe exhibit broadly similar behavioural responses to glacial-interglacial transitions and landscape development. Difficulties exist in assessing these, largely because the evidence from many rivers remains limited and fragmentary. Here we address this issue in the context of the river Kennet, a tributary of the Thames, since c. 13,000 cal BP. Some similarities with other rivers are present, suggesting that regional climatic shifts are important controls. The Kennet differs from the regional pattern in a number of ways. The rate of response to sudden climatic change, particularly at the start of the Holocene and also mid-Holocene forest clearance, appears very high. This may reflect abrupt shifts between two catchment scale hydrological states arising from contemporary climates, land use change and geology. Stadial hydrology is dominated by nival regimes, with limited winter infiltration and high spring and summer runoff. Under an interglacial climate, infiltration is more significant. The probable absence of permafrost in the catchment means that a lag between the two states due to its gradual decay is unlikely. Palaeoecology, supported by radiocarbon dates, suggests that, at the very start of the Holocene, a dramatic episode of fine sediment deposition across most of the valley floor occurred, lasting 500-1000 years. A phase of peat accumulation followed as mineral sediment supply declined. A further shift led to tufa deposition, initially in small pools, then across the whole floodplain area, with the river flowing through channels cut in tufa and experiencing repeated avulsion. Major floods, leaving large gravel bars that still form positive relief features on the floodplain, followed mid-Holocene floodplain stability. Prehistoric deforestation is likely to be the cause of this flooding, inducing a major environmental shift with significantly increased surface runoff. Since the Bronze Age, predominantly fine sediments were deposited along the valley with apparently stable channels and vertical floodplain accretion associated with soil erosion and less catastrophic flooding. The Kennet demonstrates that, while a general pattern of river behaviour over time, within a region, may be identifiable, individual rivers are likely to diverge from this. Consequently, it is essential to understand catchment controls, particularly the relative significance of surface and subsurface hydrology. (c) 2005 Elsevier B.V. All rights reserved.

Stable isotope evidence for 1500 years of human diet at the city of York, UK

We present here the results of a large-scale diachronic palaeodietary (carbon and nitrogen isotopic measurements of bone collagen) study of humans and animals from a single site, the city of York (U.K.) dating from the Roman period to the early 19th century The human sample comprises 313 burials from the cemeteries of Trentholme Drive and Blossom Street (Roman), Belle Vue House (Anglo-Saxon), Fishergate (High and Later Medieval), and All Saints, Pavement (Later and Post-Medieval). In addition, 145 samples of mammal, fish and bird bone from the sites of Tanner Row and Fishergate were analyzed. The isotope data suggest dietary variation between all archaeological periods, although the most significant change was the introduction of significant quantities of marine foods in the Medieval periods. These are first evident in the diet of a small group of individuals from the High Medieval cemetery at Fishergate, although they were consumed almost universally in the following periods. The human isotope values are also remarkable due to unusually elevated delta N-15 ratios that are not sufficiently explained by the comparably small enrichment in C-13 that accompanies them. We discuss the possible reasons behind this and the archaeological significance of the data set.