907 resultados para SITE-SPECIFIC
Resumo:
This PhD thesis focused on the analysis and application of microbial membrane lipids as biomarkers in marine sediments. Existing protocols for lipid extraction from marine sediments and biomass were modified. In addition, recent protocols based on high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS) as well as state-of-the-art mass spectrometric analysis by quadrupole time-of-flight (MSqTOF) and the triple quadrupole (MSQQQ) mass spectrometer were used to investigate matrix effects and evaluate the reliability of quantitative analysis in marine environmental samples. The improved lipid extraction and quantification were used to analyze Black Sea water column and sediments samples to a depth of 8 meters from site GeoB 15105 taken during cruise M84/1 (DARCSEAS) with R/V Meteor to apply lipid analysis in benthic bio systems. With this component specific differentiation between planktonic and benthic lipid signature we assessed possible lipid sources. Here, this high detail lipid fingerprinting allowed us to observe changes in the head group and lipid core structures of the intact polar lipids according to the geochemical zonation.
Resumo:
Increases in the low-field mass-specific magnetic susceptibility (chi), dropstones and the terrigenous sediment component from Ocean Drilling Program (ODP) Site 882 (~45°N) have been interpreted to indicate a major onset of ice-rafting to the sub-Arctic northwest Pacific Ocean during marine isotope stage (MIS) G6 (from ~2.75 Ma). In contrast, studies of the terrigenous content of sediments cored downwind of ODP Site 882 indicate that dust and disseminated volcanic ash deposition in the sub-Arctic Pacific increased markedly during MIS G6. To investigate the relative contribution of dust, volcanic ash and ice rafting to the Pliocene chi increase, we present new high-resolution environmental magnetic and ice-rafted debris records from ODP Sites 882 and 885. Our results demonstrate that the chi increase at both sites across MIS G6 is predominantly controlled by a previously overlooked mixture of aeolian dust and volcanic ash. Our findings call into question the reliability of chi as a proxy for ice-rafting to the North Pacific. They also highlight a previously undocumented link between iron fertilisation and biogeochemical cycling in the North Pacific at a key stage during intensification of late Pliocene northern hemisphere glaciation.
Resumo:
Dissolved organic matter (DOM) in marine sediments is a complex mixture of thousands of individual constituents that participate in biogeochemical reactions and serve as substrates for benthic microbes. Knowledge of the molecular composition of DOM is a prerequisite for a comprehensive understanding of the biogeochemical processes in sediments. In this study, interstitial water DOM was extracted with Rhizon samplers from a sediment core from the Black Sea and compared to the corresponding water-extractable organic matter fraction (<0.4 µm) obtained by Soxhlet extraction, which mobilizes labile particulate organic matter and DOM. After solid phase extraction (SPE) of DOM, samples were analyzed for the molecular composition by Fourier Transform Ion-Cyclotron Resonance Mass Spectrometry (FT-ICR MS) with electrospray ionization in negative ion mode. The average SPE extraction yield of the dissolved organic carbon (DOC) in interstitial water was 63%, whereas less than 30% of the DOC in Soxhlet-extracted organic matter was recovered. Nevertheless, Soxhlet extraction yielded up to 4.35% of the total sedimentary organic carbon, which is more than 30-times the organic carbon content of the interstitial water. While interstitial water DOM consisted primarily of carbon-, hydrogen- and oxygen-bearing compounds, Soxhlet extracts yielded more complex FT-ICR mass spectra with more peaks and higher abundances of nitrogen- and sulfur-bearing compounds. The molecular composition of both sample types was affected by the geochemical conditions in the sediment; elevated concentrations of HS- promoted the early diagenetic sulfurization of organic matter. The Soxhlet extracts from shallow sediment contained specific three- and four-nitrogen-bearing molecular formulas that were also detected in bacterial cell extracts and presumably represent proteinaceous molecules. These compounds decreased with increasing sediment depth while one- and two-nitrogen-bearing molecules increased, resulting in a higher similarity of both sample types in the deep sediment. In summary, Soxhlet extraction of sediments accessed a larger and more complex pool of organic matter than present in interstitial water DOM.
Resumo:
Data were presented to compare pore fluids from Sites 1037 and 1038 in the Escanaba Trough, Gorda Ridge. Site 1037 constitutes the reference site, and Site 1038 is the hydrothermally affected site. The program was undertaken for two purposes: (1) to make a detailed analysis of the halide chemistry of these two sites, with the specific aim of discerning any potential differences in the generation of dissolved halides as a result of sediment diagenesis in these drill sites and (2) to investigate the geochemistry of Ba2+ and Mn2+ at these two sites to discover potential hydrothermal effects reflected in the concentration-depth distributions of these elements.
Resumo:
A quality-controlled snow and meteorological dataset spanning the period 1 August 1993-31 July 2011 is presented, originating from the experimental station Col de Porte (1325 m altitude, Chartreuse range, France). Emphasis is placed on meteorological data relevant to the observation and modelling of the seasonal snowpack. In-situ driving data, at the hourly resolution, consist of measurements of air temperature, relative humidity, windspeed, incoming short-wave and long-wave radiation, precipitation rate partitioned between snow- and rainfall, with a focus on the snow-dominated season. Meteorological data for the three summer months (generally from 10 June to 20 September), when the continuity of the field record is not warranted, are taken from a local meteorological reanalysis (SAFRAN), in order to provide a continuous and consistent gap-free record. Data relevant to snowpack properties are provided at the daily (snow depth, snow water equivalent, runoff and albedo) and hourly (snow depth, albedo, runoff, surface temperature, soil temperature) time resolution. Internal snowpack information is provided from weekly manual snowpit observations (mostly consisting in penetration resistance, snow type, snow temperature and density profiles) and from a hourly record of temperature and height of vertically free ''settling'' disks. This dataset has been partially used in the past to assist in developing snowpack models and is presented here comprehensively for the purpose of multi-year model performance assessment. The data is placed on the PANGAEA repository (doi:10.1594/PANGAEA.774249) as well as on the public ftp server ftp://ftp-cnrm.meteo.fr/pub-cencdp/.
Resumo:
Research on the assessment of the effects of conservation/restoration treatments on stone material has been significant in recent years, with focus on the early observation of decay caused by the application of these treatments. However, in the case of archaeological sites, research is still scarce and few studies on the subject have been published. Restoration, as everything else, has changed according to trends, mainly guided by the release of new products and technologies, an experimental field where scientific assessment of suitability, efficacy and durability pre-evaluations of treatments are not always conducted. Some efforts have been made to solve this problem in the architectural field, where functional needs and technical requirements force to set clear standards. Unfortunately, archaeological sites, unlike historic buildings, have specific features that preclude the extrapolation of these results. A critical review of the methodologies, products and restoration materials is necessary, coupled with deeper research on degradation mechanisms caused by these treatments in the mid- and long-term. The aim of this paper is to introduce the research on the above issues using Merida as a case study.
Resumo:
Semantic interoperability is essential to facilitate efficient collaboration in heterogeneous multi-site healthcare environments. The deployment of a semantic interoperability solution has the potential to enable a wide range of informatics supported applications in clinical care and research both within as ingle healthcare organization and in a network of organizations. At the same time, building and deploying a semantic interoperability solution may require significant effort to carryout data transformation and to harmonize the semantics of the information in the different systems. Our approach to semantic interoperability leverages existing healthcare standards and ontologies, focusing first on specific clinical domains and key applications, and gradually expanding the solution when needed. An important objective of this work is to create a semantic link between clinical research and care environments to enable applications such as streamlining the execution of multi-centric clinical trials, including the identification of eligible patients for the trials. This paper presents an analysis of the suitability of several widely-used medical ontologies in the clinical domain: SNOMED-CT, LOINC, MedDRA, to capture the semantics of the clinical trial eligibility criteria, of the clinical trial data (e.g., Clinical Report Forms), and of the corresponding patient record data that would enable the automatic identification of eligible patients. Next to the coverage provided by the ontologies we evaluate and compare the sizes of the sets of relevant concepts and their relative frequency to estimate the cost of data transformation, of building the necessary semantic mappings, and of extending the solution to new domains. This analysis shows that our approach is both feasible and scalable.
Resumo:
Bacteria require nickel transporters for the synthesis of Ni-containing metalloenzymes in natural, low nickel habitats. In this work we carry out functional and topological characterization of Rhizobium leguminosarum HupE, a nickel permease required for the provision of this element for [NiFe] hydrogenase synthesis. Expression studies in the Escherichia coli nikABCDE mutant strain HYD723 revealed that HupE is a medium-affinity permease (apparent Km 227 ! 21 nM; Vmax 49 ! 21 pmol Ni2+ min"1 mg"1 bacterial dry weight) that functions as an energy-independent diffusion facilitator for the uptake of Ni(II) ions. This Ni2+ transport is not inhibited by similar cations such as Mn2+, Zn2+, or Co2+, but is blocked by Cu2+. Analysis of site-directed HupE mutants allowed the identification of several residues (H36, D42, H43, F69, E90, H130, and E133) that are essential for HupE-mediated Ni uptake in E. coli cells. By using translational fusions to reporter genes we demonstrated the presence of five transmembrane domains with a periplasmic N-terminal domain and a C-terminal domain buried in the lipid bilayer. The periplasmic N-terminal domain contributes to stability and functionality of the protein
Resumo:
O projeto de pesquisa Características comunicacionais do documentarismo na Internet: estudo de caso site Porta Curtas apresenta as características encontradas na exibição de documentários na Internet com as atuais tecnologias disponíveis. Tal gênero audiovisual migrou para a Internet junto a outros gêneros audiovisuais, como o telejornalismo, a telenovela e os filmes de ficção, todos com características específicas. Foi definido como corpus do trabalho o site Porta Curtas, especializado em produção audiovisual e que disponibiliza aos usuários da Internet diversas produções documentais e ficcionais gratuitamente. Espera-se, a partir deste trabalho, que adota a metodologia estudo de caso do site Porta Curtas, especializado em exibição de vídeos dos gêneros ficção e documentário, provocar novos estudos no sentido de possibilitar um maior desenvolvimento de estudos sobre a produção de documentários para as novas tecnologias que estão cada vez mais presentes no cotidiano dos processos comunicacionais, possibilitadas pelos efeitos da convergência tecnológica, assim como oferecer à comunidade científica detalhes analíticos sobre o objeto da pesquisa.(AU)
Resumo:
O projeto de pesquisa Características comunicacionais do documentarismo na Internet: estudo de caso site Porta Curtas apresenta as características encontradas na exibição de documentários na Internet com as atuais tecnologias disponíveis. Tal gênero audiovisual migrou para a Internet junto a outros gêneros audiovisuais, como o telejornalismo, a telenovela e os filmes de ficção, todos com características específicas. Foi definido como corpus do trabalho o site Porta Curtas, especializado em produção audiovisual e que disponibiliza aos usuários da Internet diversas produções documentais e ficcionais gratuitamente. Espera-se, a partir deste trabalho, que adota a metodologia estudo de caso do site Porta Curtas, especializado em exibição de vídeos dos gêneros ficção e documentário, provocar novos estudos no sentido de possibilitar um maior desenvolvimento de estudos sobre a produção de documentários para as novas tecnologias que estão cada vez mais presentes no cotidiano dos processos comunicacionais, possibilitadas pelos efeitos da convergência tecnológica, assim como oferecer à comunidade científica detalhes analíticos sobre o objeto da pesquisa.(AU)