1000 resultados para MAGMA EVOLUTION


Relevância:

20.00% 20.00%

Publicador:

Resumo:

A landscape mosaic is a landscape that consist of various patches, inhabited by different habitat communities over time. Agricultural mosaics area result of the long history between societies and the environment. The understanding of the driving forces for change in this landscapes, and their effect on biodiversity, allow the development of useful tools to assess and manage natural heritage. Plant diversity, endangered plant species and interesting habitats receive the center of attention, because of their capability to integrate and reflect the main changes of this landscapes after medium and long-term.

Relevância:

20.00% 20.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Antibodies are natural binding proteins produced in vertebrates as a response to invading pathogens and foreign substances. Because of their capability for tight and specific binding, antibodies have found use as binding reagents in research and diagnostics. Properties of cloned recombinant antibodies can be further improved by means of in vitro evolution, combining mutagenesis with subsequent phage display selection. It is also possible to isolate entirely new antibodies from vast naïve or synthetic antibody libraries by phage display. In this study, library techniques and phage display selection were applied in order to optimise binding scaffolds and antigen recognition of antibodies, and to evolve new and improved bioaffinity reagents. Antibody libraries were generated by random and targeted mutagenesis. Expression and stability were mainly optimised by the random methods whereas targeted randomisation of the binding site residues was used for optimising the binding properties. Trinucleotide mutagenesis allowed design of defined randomisation patterns for a synthetic antibody library. Improved clones were selected by phage display. Capture by a specific anti- DHPS antibody was exploited in the selection of improved phage display of DHPS. Efficient selection for stability was established by combining phage display selection with denaturation under reducing conditions. Broad-specific binding of a generic anti-sulfonamide antibody was improved by selection with one of the weakest binding sulfonamides. In addition, p9 based phage display was studied in affinity selection from the synthetic library. A TIM barrel protein DHPS was engineered for efficient phage display by combining cysteinereplacement with random mutagenesis. The resulting clone allows use of phage display in further engineering of DHPS and possibly use as an alternative-binding scaffold. An anti-TSH scFv fragment, cloned from a monoclonal antibody, was engineered for improved stability to better suite an immunoassay. The improved scFv tolerates 8 – 9 °C higher temperature than the parental scFv and should have sufficient stability to be used in an immunoanalyser with incubation at 36 °C. The anti-TSH scFv fragment was compared with the corresponding Fab fragment and the parental monoclonal antibody as a capturing reagent in a rapid 5-min immunoassay for TSH. The scFv fragment provided some benefits over the conventionally used Mab in anayte-binding capacity and assay kinetics. However, the recombinant Fab fragment, which had similar kinetics to the scFv, provided a more sensitive and reliable assay than the scFv. Another cloned scFv fragment was engineered in order to improve broad-specific recognition of sulfonamides. The improved antibody detects different sulfonamides at concentrations below the maximum residue limit (100 μg/kg in EU and USA) and allows simultaneous screening of different sulfonamide drug residues. Finally, a synthetic antibody library was constructed and new antibodies were generated and affinity matured entirely in vitro. These results illuminate the possibilities of phage display and antibody engineering for generation and optimisation of binding reagents in vitro and indicate the potential of recombinant antibodies as affinity reagents in immunoassays.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Most metazoans rely on aerobic energy production, which is dependent on adequate oxygen supply. In the case of reduced oxygen supply (hypoxia), the most profound changes in gene expression are mediated by transcription factors named hypoxia-inducible factors (HIF alpha). These proteins are post-translationally regulated by prolyl-4-hydroxylase (PHD) enzymes that are direct “sensors” of cellular oxygen levels. This thesis examines the molecular evolution of metazoan HIF systems. In early metazoans the HIF system emerged from pre-existing PHD oxygen sensors and early bHLH-PAS transcription factors. In invertebrates our analysis revealed an unexpected diversity of PHD genes and HIF alpha sequence characteristics. An early branching vertebrate, the epaulette shark (Hemiscyllium ocellatum) was chosen for sequencing and hypoxia preconditioning studies of HIF alpha and PHD genes. As no quantitative PCR reference genes were available, this thesis includes the first study of reference genes in cartilaginous fish species. Applying multiple statistical analysis we also discoveredthat commonly used reference gene software may perform poorly with some data sets. Novel reference genes allowed accurate measurements of the mRNAlevels of the studied target genes. Cartilaginous fishes have three genomic duplicates of both HIF alpha and PHD genes like mammals and teleost fishes. Combining functional divergence and selection analyses it was possible to describe how sequence changes in both HIF alpha and PHD duplicates may have contributed to the differential oxygen sensitivityof HIF alphas. Additionally, novel teleost HIF-1 alpha sequences were produced and used to reveal the molecular evolution of HIF-1 alpha in this lineage rich with hypoxia tolerant species.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A small carbonatite dyke swarm has been identified at Naantali, southwest Finland. Several swarms of shoshonitic lamprophyres are also known along the Archean-Proterozoic boundary in eastern Finland and northwest Russia. These intrusions, along with the carbonatite intrusion at Halpanen, eastern Finland, represent a stage of widespread low-volume mantle-sourced alkaline magmatism in the Svecofennian Domain. Using trace element and isotope geochemistry coupled with precise geochronology from these rocks, a model is presented for the Proterozoic metasomatic evolution of the Fennoscandian subcontinental lithospheric mantle. At ~2.2-2.06 Ga, increased biological production in shallow seas linked to continental rifting, resulted in increased burial rates of organic carbon. Subduction between ~1.93-1.88 Ga returned organic carbon-enriched sediments of mixed Archean and Proterozoic provenance to the mantle. Dehydration reactions supplied water to the mantle wedge, driving arc volcanism, while mica, amphibole and carbonate were brought deeper into the mantle with the subducting slab. The cold subducted slab was heated conductively from the surrounding warm mantle, while pressures continued to gradually increase as a result of crustal thickening. The sediments began to melt in a two stage process, first producing a hydrous alkaline silicate melt, which infiltrated the mantle wedge and crystallised as metasomatic veins. At higher temperatures, carbonatite melt was produced, which preferentially infiltrated the pre-existing metasomatic vein network. At the onset of post-collisional extension, deep fault structures formed, providing conduits for mantle melts to reach the upper crust. Low-volume partial melting of the enriched mantle at depths of at least 110 km led to the formation of first carbonatitic magma and subsequently lamprophyric magma. Carbonatite was emplaced in the upper crust at Naantali at 1795.7 ± 6.8 Ma; lamprophyres along the Archean-Proterozoic boundary were emplaced between 1790.1 ± 3.3 Ma and 1781 ± 20 Ma.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The rice grain is frequently infected by a series of pathogens (fungi) during its storage, producing damages to the economy and health of humans. The aim of this study was to identify the fungal genera present in different rice genotypes and to quantify their variation during storage. Paddy, brown and milled rice fractions of Nutriar, (N) H329-5(H329) and Don Ignacio genotypes were analyzed at 4, 8 and 12 months of storage. Fungi were identified based on their micromorphological characteristics and colonies. The observed genera according to their frequency were: Alternaria, Nigrospora, Epicoccum, Bipolaris, Curvularia, Cladosporium and Fusarium (field fungi) and Penicillium and Aspergillus (storage fungi). The mycobiota composition was different depending on the grain fraction and the period of storage: field fungi were located in the hulls and bran layers, while storage fungi were mainly in the endosperm. The different genotypes showed different susceptibility to contamination.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Evolution of Bordetella pertussis post vaccination Whooping cough or pertussis is caused by the gram-negative bacterium Bordetella pertussis. It is a highly contiguous disease in the human respiratory tract. Characteristic of pertussis is a paroxysmal cough with whooping sound during gasps of breath after coughing episodes. It is potentially fatal to unvaccinated infants. The best approach to fight pertussis is to vaccinate. Vaccinations against pertussis have been available from the 1940s. Traditionally vaccines were whole-cell pertussis (wP) preparations as part of the combined diphtheria-tetanus-pertussis (DTP) vaccines. More recently acellular pertussis (aP) vaccines have replaced the wP vaccines in many countries. The aP vaccines are less reactogenic and can also be administered to school children and adults. There are several publications reporting variation in the i>B. pertussis virulence factors that are also aP vaccine antigens. This has occurred in the genes coding for pertussis toxin and pertactin about 15 to 30 years after the introduction of pertussis vaccines to immunisation programs. Resurgence of pertussis has also been reported in many countries with high vaccination coverage. In this study the evolution of B. pertussis was investigated in Finland, the United Kingdom, Poland, Serbia, China, Senegal and Kenya. These represent countries with a long history of high vaccination coverage with stable vaccines or changes in the vaccine formulation; countries which established high vaccination coverage late; and countries where vaccinations against pertussis were started late. With bacterial cytotoxicity and cytokine measurements, comparative genomic hybridisation, pulsed-field gel electrophoresis (PFGE), genotyping and serotyping it was found that changes in the vaccine composition can postpone the emergence of antigenic variants. It seems that the change in PFGE profiles and the loss of genetic material in the genome of B. pertussis are similar in most countries and the vaccine-induced immunity is selecting non-vaccine type strains. However, the differences in the formulation of the vaccines, the vaccination programs and in the coverage of pertussis vaccination have affected the speed and timing of these changes.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The objective of the thesis is to enhance understanding of the evolution of convergence. Previous research has shown that the technological interfaces between distinct industries are one of the major sources of new radical cross-industry innovations. Despite the fact that convergence in industry evolution has attracted a substantial managerial interest, the conceptual confusion within the field of convergence exists. Firstly, this study clarifies the convergence phenomenon and its impact to industry evolution. Secondly, the study creates novel patent analysis methods to analyze technological convergence and provide tools for anticipating the early stages of convergence. Overall the study combines the industry evolution perspective and the convergence view of industrial evolution. The theoretical background for the study consists of the industry life cycle theories, technology evolution, and technological trajectories. The study links several important concepts in analyzing industry evolution, technological discontinuities, path-dependency, technological interfaces as a source of industry transformation, and the evolutionary stagesof convergence. Based on reviewing the literature a generic understanding of industry transformation and industrial dynamics was generated. In the convergence studies, the theoretical basis is in the discussion of different convergence types and their impacts on industry evolution, and in anticipating and monitoring the stages of convergence. The study is divided in two parts. The first part gives a general overview, and the second part comprises eight research publications. Our case study is based historically on two very distinct industries of the paper and electronics companies as a test environment to evaluate the importance of emerging business sectors and technological convergence as a source of industry transformation. Both qualitative and quantitative research methodology are utilized. The results of this study reveal that technological convergence and complementary innovations from different fields have significant effect to the emerging new business sector formation. The patent-based indicators in the analysis of technological convergence can be utilized on analyzing technology competition, capability and competence development, knowledge accumulation, knowledge spill-overs, and technology-based industry transformation. The patent-based indicators can provide insights to the future competitive environment. Results and conclusions from empirical part seem not be in conflict with real observations in the industry.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

It was evaluated the annual evolution of global, direct and diffuse components of incident solar radiation on tilted surfaces to 12.85, 22.85 and 32.85º, facing north, in Botucatu, state of São Paulo, Brazil. The radiometric fractions were obtained for each component of the radiation in the aforementioned surfaces, through the ratio with the global and top of the atmosphere radiations. Seasonality was evaluated based on monthly averages of daily values. The measures occurred between 04/1998 and 07/2001 at 22.85º; 08/2001 and 02/2003 at 12.85º; and from 03/2003 to 12/2007 at 32.85º, with concomitant measures in the horizontal surface (reference). The levels of global and direct radiation on tilted surfaces were lower in summer and higher in the equinoxes when compared with the horizontal. The diffuse radiation on tilted surfaces was lower in most months, with losses of up to 65%. A trend of increasing differences occurred between horizontal and tilted surfaces with the increase of the angle in all the components and fractions of incident radiation. The annual evolution of rainfall and cloud cover ratio directly affected the atmospheric transmissivity of direct and diffuse components in the region.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The objective of this thesis work is to develop and study the Differential Evolution Algorithm for multi-objective optimization with constraints. Differential Evolution is an evolutionary algorithm that has gained in popularity because of its simplicity and good observed performance. Multi-objective evolutionary algorithms have become popular since they are able to produce a set of compromise solutions during the search process to approximate the Pareto-optimal front. The starting point for this thesis was an idea how Differential Evolution, with simple changes, could be extended for optimization with multiple constraints and objectives. This approach is implemented, experimentally studied, and further developed in the work. Development and study concentrates on the multi-objective optimization aspect. The main outcomes of the work are versions of a method called Generalized Differential Evolution. The versions aim to improve the performance of the method in multi-objective optimization. A diversity preservation technique that is effective and efficient compared to previous diversity preservation techniques is developed. The thesis also studies the influence of control parameters of Differential Evolution in multi-objective optimization. Proposals for initial control parameter value selection are given. Overall, the work contributes to the diversity preservation of solutions in multi-objective optimization.