985 resultados para Content-independent embedding
Resumo:
A unique set of geochemical pore-water data, characterizing the sulfate reduction and uppermost methanogenic zones, has been collected at the Blake Ridge (offshore southeastern North America) from Ocean Drilling Program (ODP) Leg 164 cores and piston cores. The d13C values of dissolved CO2 (sum CO2) are as 13C-depleted as -37.7 per mil PDB (Site 995) at the sulfate-methane interface, reflecting a substantial contribution of isotopically light carbon from methane. Although the geochemical system is complex and difficult to fully quantify, we use two methods to constrain and illustrate the intensity of anaerobic methane oxidation in Blake Ridge sediments. An estimate using a two-component mixing model suggests that ~24% of the carbon residing in the sum CO2 pool is derived from biogenic methane. Independent diagenetic modeling of a methane concentration profile (Site 995) indicates that peak methane oxidation rates approach 0.005 µmol/cm**3/yr, and that anaerobic methane oxidation is responsible for consuming ~35% of the total sulfate flux into the sediments. Thus, anaerobic methane oxidation is a significant biogeochemical sink for sulfate, and must affect interstitial sulfate concentrations and sulfate gradients. Such high proportions of sulfate depletion because of anaerobic methane oxidation are largely undocumented in continental rise sediments with overlying oxic bottom waters. We infer that the additional amount of sulfate depleted through anaerobic methane oxidation, fueled by methane flux from below, causes steeper sulfate gradients above methane-rich sediments. Similar pore water chemistries should occur at other methane-rich, continental-rise settings associated with gas hydrates.
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Singlet oxygen is a prominent form of reactive oxygen species in higher plants. It is easily formed from molecular oxygen by triplet–triplet interchange with excited porphyrin species. Evidence has been obtained from studies on the flu mutant of Arabidopsis thaliana of a genetically determined cell death pathway that involves differential changes at the transcriptome level. Here we report on a different cell death pathway that can be deduced from the analysis of oep16 mutants of A. thaliana. Pure lines of four independent OEP16-deficient mutants with different cell death properties were isolated. Two of the mutants overproduced free protochlorophyllide (Pchlide) in the dark because of defects in import of NADPH:Pchlide oxidoreductase A (pPORA) and died after illumination. The other two mutants avoided excess Pchlide accumulation. Using pulse labeling and polysome profiling studies we show that translation is a major site of cell death regulation in flu and oep16 plants. flu plants respond to photooxidative stress triggered by singlet oxygen by reprogramming their translation toward synthesis of key enzymes involved in jasmonic acid synthesis and stress proteins. In contrast, those oep16 mutants that were prone to photooxidative damage were unable to respond in this way. Together, our results show that translation is differentially affected in the flu and oep16 mutants in response to singlet oxygen.
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he nitrogen content dependence of the electronic properties for copper nitride thin films with an atomic percentage of nitrogen ranging from 26 ± 2 to 33 ± 2 have been studied by means of optical (spectroscopic ellipsometry), thermoelectric (Seebeck), and electrical resistivity measurements. The optical spectra are consistent with direct optical transitions corresponding to the stoichiometric semiconductor Cu3N plus a free-carrier contribution, essentially independent of temperature, which can be tuned in accordance with the N-excess. Deviation of the N content from stoichiometry drives to significant decreases from − 5 to − 50 μV/K in the Seebeck coefficient and to large enhancements, from 10− 3 up to 10 Ω cm, in the electrical resistivity. Band structure and density of states calculations have been carried out on the basis of the density functional theory to account for the experimental results.
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The endothelial isoform of NO synthase (eNOS) is targeted to sphingolipid-enriched signal-transducing microdomains in the plasma membrane termed caveolae. Among the caveolae-targeted sphingolipids are the ceramides, a class of acylated sphingosine compounds that have been implicated in diverse cellular responses. We have explored the role of ceramide analogues in eNOS signaling in cultured bovine aortic endothelial cells (BAEC). Addition of the ceramide analogue N-acetylsphingosine (C2-ceramide; 5 μM) to intact BAEC leads to a significant increase in NO synthase activity (assayed by using the fluorescent indicator 4,5-diaminofluorescein) and translocation of eNOS from the endothelial cell membrane to intracellular sites (measured by using quantitative immunofluorescence techniques); the biologically inactive ceramide N-acetyldihydrosphingosine is entirely without effect. C2-ceramide-induced eNOS activation and translocation are unaffected by the intracellular calcium chelator 1,2-bis-o-aminophenoxyethane-N,N,N′,N′-tetraacetic acid (BAPTA). Using the calcium-specific fluorescent indicator fluo-3, we also found that C2-ceramide activation of eNOS is unaccompanied by a drug-induced increase in intracellular calcium. These findings stand in sharp contrast to the mechanism by which bradykinin, estradiol, and other mediators acutely activate eNOS, in which a rapid, agonist-promoted increase in intracellular calcium is required. Finally, we show that treatment of BAEC with bradykinin causes a significant increase in cellular ceramide content; the response to bradykinin has an EC50 of 3 nM and is blocked by the bradykinin B2-receptor antagonist HOE140. Bradykinin-induced ceramide generation could represent a mechanism for longer-term regulation of eNOS activity. Our results suggest that ceramide functions independently of Ca2+-regulated pathways to promote activation and translocation of eNOS, and that this lipid mediator may represent a physiological regulator of eNOS in vascular endothelial cells.
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Formation of the vertebrate axial skeleton requires coordinated Hox gene activity. Hox group 6 genes are involved in the formation of the thoracic area owing to their unique rib-promoting properties. Here we show that the linker region (LR) connecting the homeodomain and the hexapeptide is essential for Hoxb6 rib-promoting activity in mice. The LR-defective Hoxb6 protein was still able to bind a target enhancer together with Pax3, producing a dominant-negative effect, indicating that the LR brings additional regulatory factors to target DNA elements. We also found an unexpected association between Hoxb6 and segmentation in the paraxial mesoderm. In particular, Hoxb6 can disturb somitogenesis and anterior-posterior somite patterning by dysregulation of Lfng expression. Interestingly, this interaction occurred differently in thoracic versus more caudal embryonic areas, indicating functional differences in somitogenesis before and after the trunk-to-tail transition. Our results suggest the requirement of precisely regulated Hoxb6 expression for proper segmentation at tailbud stages.
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Sediment samples were obtained for detailed Adenosine 5'-Triphosphate (ATP) analysis down to 57.8 m below the seafloor (mbsf). The samples were also analyzed for particle-size distribution, calcium carbonate (CaCO3), organic carbon, and total nitrogen. The concentrations of ATP ranged between 360 and 7050 pg/g (dry weight sediment), which agree well with a limited number of direct bacteria counts. Principal component analyses show that 63% of the total variance can be accounted for by the first two principal components. The concentration of ATP (bacterial numbers by inference) is virtually independent of the concentration of sedimentary organic carbon, but correlates with CaCO3 and coarse particles.
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Strontium concentrations and 87Sr/86Sr values were measured on pore-water and sedimentary carbonate samples from sediments recovered at Sites 1049-1053 on the Blake Spur during Ocean Drilling Program Leg 171B. These sites form a 40-km-long depth transect extending along the crest of the Blake Spur from near the upper edge of the Blake Escarpment (a steep cliff composed of Mesozoic carbonates) westward toward the interior of the Blake-Bahama Platform. Although these sites were selected for paleoceanographic purposes, they also form a hydrologic transect across the upper eastern flank of the Blake-Bahama Platform. Here, we use pore-water strontium concentrations and isotopes as a proxy to define patterns of fluid movement through the flanks of this platform. Pore-water strontium concentration increases with depth at all sites implying that strontium has been added during sediment burial and diagenesis. The isotopic values decrease from seawater-like values in the shallow samples (~0.70913) to values as low as 0.707342 in one of the deepest samples (~625 meters below seafloor). The change in pore-water strontium isotopic values is independent of the strontium isotopic compositions predicted from the host sediment age and measured on bulk carbonate in some samples. In most cases the difference between predicted sediment strontium isotopic composition and measured value is less than ±2 about the mean of the measured strontium value. Both the increase in concentration and the decrease in the strontium isotope values with increasing depth indicate that strontium was expelled from older carbonates. The strontium concentration and isotope profiles vary between sites according to their proximity to the Blake-Bahama Platform edge. Profiles from Site 1049 (nearest the platform edge) show the greatest amount of mixing with modern seawater, whereas the site most distal to the platform edge (Site 1052) shows the most significant influence of older, deeper carbonates on the pore-water strontium isotopic composition.
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A new principled domain independent watermarking framework is presented. The new approach is based on embedding the message in statistically independent sources of the covertext to mimimise covertext distortion, maximise the information embedding rate and improve the method's robustness against various attacks. Experiments comparing the performance of the new approach, on several standard attacks show the current proposed approach to be competitive with other state of the art domain-specific methods.
Resumo:
The improving performance of public administration and the reform of public financing system have been on agenda in Hungary for many years, in accordance with the international trends. However, governments have not expected and supported creating of a performance-oriented public administration in a comprehensive and explicit way. Nevertheless, there are bottom-up initiatives at organizational level, which target performance-oriented organizational function. The research focuses on organizations of central public administration where the successful application of performance management methods is most likely based on the international literature. These are the so called agency-type organizations, which are in Hungary called autonomous state-administration organizations independent of the Government (e.g. Hungarian Competition Authority), government bureaus (e.g. Hungarian Central Statistical Office), and central offices subordinated to the government (either the cabinet or a ministry) (e.g. Hungarian Meteorological Service). The studied agencies are legally independent organizations with managerial autonomy based on public law. The purpose of this study is to get an overview on organizational level performance management tools applied by Hungarian agencies, and to reveal the reasons and drivers of the application of these tools. The empirical research is based on a mixed methods approach which combines both quantitative methods and qualitative procedures. The first – quantitative – phase of the author’s research was content analysis of homepages of the studied organizations. As a results she got information about all agencies and their practice related to some performance management tools. The second – qualitative – phase was based on semi-structured face-to-face interviews with some senior managers of agencies. The author selected the interviewees based on the results of the first phase, the relatively strong performance orientation was an important selection criteria.
Resumo:
This Paper discusses the food and beverage machines that are located at Memorial University's Grenfell Campus and endeavors to assess how much those vending machines are being used and how they affect sustainability initiatives on campus. A survey was conducted to gauge the use of vending machines, their content and what is purchased, and if participants did not purchase from thes machines they were also asked why they did not.This survey produced many other questions that are directly linked to vending machines.Water quality on campus was heavily disscussed, along with the use of bottled water and implications associated with drinking only from bottles that are thrown away. The study concludes with a discussion of the alternative choices that can be implemented to replace vending machines.
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Although soil algae are among the main primary producers in most terrestrial ecosystems of continental Antarctica, there are very few quantitative studies on their relative proportion in the main algal groups and on how their distribution is affected by biotic and abiotic factors. Such knowledge is essential for understanding the functioning of Antarctic terrestrial ecosystems. We therefore analyzed biological soil crusts from northern Victoria Land to determine their pH, electrical conductivity (EC), water content (W), total and organic C (TC and TOC) and total N (TN) contents, and the presence and abundance of photosynthetic pigments. In particular, the latter were tested as proxies for biomass and coarse-resolution community structure. Soil samples were collected from five sites with known soil algal communities and the distribution of pigments was shown to reflect differences in the relative proportions of Chlorophyta, Cyanophyta and Bacillariophyta in these sites. Multivariate and univariate models strongly indicated that almost all soil variables (EC, W, TOC and TN) were important environmental correlates of pigment distribution. However, a significant amount of variation is independent of these soil variables and may be ascribed to local variability such as changes in microclimate at varying spatial and temporal scales. There are at least five possible sources of local variation: pigment preservation, temporal variations in water availability, temporal and spatial interactions among environmental and biological components, the local-scale patchiness of organism distribution, and biotic interactions.
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Focusing on the UK, this article addresses key issues facing the international distribution industry arising from over-the-top digital distribution and the fragmentation of audiences and revenues. Building on the identification of these issues, it investigates the extent to which UK distribution has altered over a ten-year period, pinpointing continuities in the destination and type of sales alongside changes in the role and structure of the industry as UK-based distributors adapt to a changing UK broadcasting landscape and global production environment. At one level increasing US ownership of UK-based distributors and the arrival of OTT players like Netflix, highlight the tensions between the national orientations of UK broadcasters and the global aspirations of independent producers and distributors. At another level VOD has boosted international sales of UK drama. Although the full impact of SVOD on content and rights has yet to materialise, significant changes in the industry predate the arrival of SVOD.
Resumo:
Content Centric Network (CCN) is a proposed future internet architecture that is based on the concept of contents name instead of the hosts name followed in the traditional internet architecture. CCN architecture might do changes in the existing internet architecture or might replace it completely. In this paper, we present modifications to the existing Domain Name System (DNS) based on the CCN architecture requirements without changing the existing routing architecture. Hence the proposed solution achieves the benefits of both CCN and existing network infrastructure (i.e. content based routing, independent of host location, caching and content delivery protocols).
Resumo:
Objectives: To explore the content and methodology of predoctoral Geriatric Dentistry teaching amongst European dental schools.
Methods: The study was conducted by the European College of Gerodontology (ECG) Education Committee. Αn electronic questionnaire has been developed with close and open-ended items, including information on the prevalence and institutional anchorage of Gerodontology programs, the educators, the content and the methodology of teaching. An electronic mail, including a hyperlink to the questionnaire, was sent to 216 dental schools in 39 European countries (Winter/ Spring 2016). The Deans were asked to either answer themselves, or forward the link to faculty members with knowledge on Gerodontology teaching at their respective schools. Repeated reminders or telephone calls were used for non-respondents and personal networks were exploited to identify potential contact persons.
Results: Until August 2016, 121 dental schools from 29 countries responded to the survey (response rate 56%, EU response rate: 60%). Gerodontology was included in the predoctoral curricula of 86% of the respondents and was compulsory in 68%. The course was mainly offered in senior students and was interdisciplinary in 30% of the schools, delivered mainly by dentists (79%), physicians (21%), psychologists (10%), and nurses (5%). It was conducted as an independent lecture series in 40% of the schools and a course director was assigned in 44% of the respondents. When embedded in other disciplines, these were mainly Prosthodontics (31%). The content included a large number of items, such as epidemiology of oral health, medical problems in old age, prosthodontic management, xerostomia, and caries risk assessment. Lectures were the most common teaching format (69%), followed by small group seminars (27%). The most common types of educational material used were scientific articles (48%), printed textbooks (44%), lecture notes (40%) and e-learning material (21%). Clinical training was offered by 64% of the respondents, within the dental school clinics (49%) and/or in outreach locations (40%).
Conclusion: Amongst the respondent European dental schools (66%) there is an increasing number that teach Gerodontology at a pre-doctoral level with significant variations in content and methodology. Official guidelines and the dissemination of the ECG pre-doctoral curriculum guidelines might help to increase the prevalence and improve the status of Gerodontology teaching in Europe.