150 research outputs found

    Novel superconducting phases of Tl-based compounds

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    Researchers report the measurements of the I(sub c)(T) of the 102 K phase. They also discuss briefly the composition of the lattice parameters and the ac susceptibility relation to the grain size and microstructure

    Asymptotic equivalence of impulsive differential equations in a Banach space

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    By means of Schauder's fixed point theorem sufficient conditions for asymptotic equivalence of impulsive equations in a Banach space are found

    Novel superconducting phases of Tl-based compounds

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    Several new superconducting phases of the Tl-based compounds were prepared. Structural studies revealed cell lengths of 31.9 A and longer. Properties of Ce-containing compounds are also discussed

    Lake-atmosphere interactions at Alqueva reservoir : a case study in the summer of 2014

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    The study of lake-atmosphere interactions was the main purpose of a 2014 summer experiment at Alqueva reservoir in Portugal. Near-surface fluxes of momentum, heat and mass [water vapour (H2O) and carbon dioxide (CO2)] were obtained with the new Campbell Scientific's IRGASON Integrated Open-Path CO2/H2O Gas Analyser and 3D Sonic Anemometer between 2 June and 2 October. On average, the reservoir was releasing energy in the form of sensible and latent heat flux during the study period. At the end of the 75 d, the total evaporation was estimated as 490.26 mm. A high correlation was found between the latent heat flux and the wind speed (R = 0.97). The temperature gradient between air and water was positive between 12 and 21 UTC, causing a negative sensible heat flux, and negative during the rest of the day, triggering a positive sensible heat flux. The reservoir acted as a sink of atmospheric CO2 with an average rate of -0.026 mg m(-2) s(-1). However, at a daily scale we found an unexpected uptake between 0 and 9 UTC and almost null flux between 13 and 19 UTC. Potential reasons for this result are further discussed. The net radiation was recorded for the same period and water column heat storage was estimated using water temperature profiles. The energy balance closure for the analysed period was 81%. In-water solar spectral downwelling irradiance profiles were measured with a new device allowing measurements independent of the solar zenith angle, which enabled the computation of the attenuation coefficient of light in the water column. The average attenuation coefficient for the photosynthetically active radiation spectral region varied from 0.849 +/- 0.025 m(-1) on 30 July to 1.459 +/- 0.007 m(-1) on 25 September.Peer reviewe

    Ecogenomic Perspectives on Domains of Unknown Function: Correlation-Based Exploration of Marine Metagenomes

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    Background: The proportion of conserved DNA sequences with no clear function is steadily growing in bioinformatics databases. Studies of sequence and structural homology have indicated that many uncharacterized protein domain sequences are variants of functionally described domains. If these variants promote an organism's ecological fitness, they are likely to be conserved in the genome of its progeny and the population at large. The genetic composition of microbial communities in their native ecosystems is accessible through metagenomics. We hypothesize the co-variation of protein domain sequences across metagenomes from similar ecosystems will provide insights into their potential roles and aid further investigation. Methodology/Principal findings: We calculated the correlation of Pfam protein domain sequences across the Global Ocean Sampling metagenome collection, employing conservative detection and correlation thresholds to limit results to well-supported hits and associations. We then examined intercorrelations between domains of unknown function (DUFs) and domains involved in known metabolic pathways using network visualization and cluster-detection tools. We used a cautious "guilty-by-association'' approach, referencing knowledge-level resources to identify and discuss associations that offer insight into DUF function. We observed numerous DUFs associated to photobiologically active domains and prevalent in the Cyanobacteria. Other clusters included DUFs associated with DNA maintenance and repair, inorganic nutrient metabolism, and sodium-translocating transport domains. We also observed a number of clusters reflecting known metabolic associations and cases that predicted functional reclassification of DUFs. Conclusion/Significance: Critically examining domain covariation across metagenomic datasets can grant new perspectives on the roles and associations of DUFs in an ecological setting. Targeted attempts at DUF characterization in the laboratory or in silico may draw from these insights and opportunities to discover new associations and corroborate existing ones will arise as more large-scale metagenomic datasets emerge

    Comparative study of heparin- and toluidine blue positive mast cells in porcine lumbar spinal ganglia

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    In the present study, toluidine blue for metachromasia and berberine sulfate for heparin fluorescence were used to determine the localisation and distribution of mast cells as well as the percent of hepa-rin-positive cells (MCH) in normal lumbar spinal ganglia (dorsal root ganglia) of domestic swine. Mast cells density was established after estimating the number of these cells per ganglion. Mast cells with metachromasia (MCTB) were observed predominantly in the ganglion capsule near the blood vessels. The number of mast cells inside the ganglia (2.10±1.45 in males and 2.20±1.03 in females) was significantly lower than in the capsule (13.30±1.95 in males and 13.60±2.42 in females) in both genders (P<0.001). Sexual dimorphism of the studied parameters was not established except for the slightly higher number of mast cells localised inside the left spinal ganglia of females than in males (P<0.05). The localisation of heparin-positive mast cells and the ratio between them and mast cells stained with toluidine blue (almost 2:1) was also determined. The percentage of heparin-positive mast cells in the ganglion capsule was 4 %, whereas inside the ganglion – 40%

    A multi-input UV-VIS airborne GASCOD/A4r spectroradiometer for the validation of satellite remote sensing measurements

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    The present paper describes a UV-VIS spectroradiometer named GASCOD/A4r developed at ISAC-CNR for remote sensing measurements aboard stratospheric M55-Geophysica aircraft, flying up to 21 km. Obtained experimental data are used for retrieving of NO2, O3 and of other minor gases atmospheric content, applying the DOAS (Differential Optical Absorption Spectroscopy) method. UV actinic flux and J(NO2) are also derived. All these parameters are used for satellite data validation tasks. The specific results obtained during dedicated aircraft missions in different geographical areas have already been utilized for ENVISAT validation

    Herb Stem Cutter -Design and Research

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    Abstract IVANOV, D., G. KOSTADINOV, T. MITOVA and I. DIMITROV, 2006. Herb stem cutter -design and research. Bulg. J. Agric. Sci., The article presents the results of investigations on a herb stem cutting machine. Investigations were performed as a series of controlled single-factor experiments. The basic target functions of the study were as follows: drive&apos;s absorbed power of the machine (kW); specific energy consumption (kWh/t) and average cutting length (mm). The levels of controlled trial factors were as follows: machine load capacity with herb stem mass: Q = 0.5; 1 and 1.5 kg/s and feeding velocity of stem mass to the cutting drum: V = 2.0; 2.4 and 2.8 m/s. Here are the factors, maintained at stable levels: cutting drum peripheral velocity -25 m/s at rotation frequency of 1176 min -1 ; cutting drum working width -Β=0.558 mm; cutting drum diameter D=0.406 m; number of blades z=6; blade thickness b=10 mm; blade sharpening angle β=34°; inclination of blades&apos; edges to the counteredge α=15°; front cutting angle ϕ=50°; gap between blade and counterblade edges ∆=0.5 mm; sharpening angle of the counterblade β 1 =90° and sharpness of counterblade cutting edge δ=0.2 mm. The correlation between the variation of drive&apos;s absorbed power for startup of the cutting drum, specific energy consumption and average cutting length, on the one hand, and the variation of controlled factors, on the other, was established. The respective adequate regression equations were simulated, describing the herb stem cutting processes with specific accuracy
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