2,628 research outputs found

    Caractérisation des situations hydro-biologiques et potentialités de pêche thonière au Cap Lopez en Juin et Juillet 1972 et 1974

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    Surface temperature was measured by remote sensing through Cape Lopez (Gulf of Guinea) frontal region during the fishing season in June and July 1972 and 1974. Twelve typical situations are analysed through four main directions: surface situation, tendency, hydrobiological structure and availability to fisheries. The tuna behavior is analysed in relation with the frontal zone movements and a mechanism which tends to aggregate important shoals of tunas is presented

    Electronically synthesized Nyquist pulses for photonic sampling of microwave signals

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    We report electronic generation of optical Nyquist pulses using an arbitrary waveform generator (AWG) followed by a Mach Zehnder modulator (MZM), providing a simple, highly stable and flexible technique to perform photonic sampling. Here, we demonstrate the generation of 10 GHz periodic optical Nyquist pulses by synthesizing both all-positive and alternate positive-negative electrical pulse trains using a 25 GHz bandwidth AWG. Biasing the MZM at null ensures the meeting of the Nyquist ISI-free criterion in the optical domain and allows for pulse compression. Moreover, we report the first photonic sampling and demodulation of 1 Gbaud 16- and 32-QAM signals up to 22.5 GHz using 10 GHz optical Nyquist sampling pulse trains

    Inhibition Of Mitochondrial Permeability Transition By Low Ph Is Associated With Less Extensive Membrane Protein Thiol Oxidation.

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    Ca2+ and inorganic phosphate-induced mitochondrial swelling and membrane protein thiol oxidation, which are associated with mitochondrial permeability transition, are inhibited by progressively decreasing the incubation medium pH between 7.2 and 6.0. Nevertheless, the detection of mitochondrial H2O2 production under these conditions is increased. Permeability transition induced by phenylarsine oxide, which promotes membrane protein thiol cross-linkage in a process independent of Ca2+ or reactive oxygen species, is also strongly inhibited in acidic incubation media. In addition, we observed that the decreased protein thiol reactivity with phenylarsine oxide or phenylarsine oxide-induced swelling at pH 6.0 is reversed by diethyl pyrocarbonate, in a hydroxylamine-sensitive manner. These results provide evidence that the inhibition of mitrochondrial permeability transition observed at lower incubation medium pH is mediated by a decrease in membrane protein thiol reactivity, related to the protonation of protein histidyl residues.19525-3

    Respiration, Oxidative Phosphorylation, And Uncoupling Protein In Candida Albicans.

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    The respiration, membrane potential (Deltapsi), and oxidative phosphorylation of mitochondria in situ were determined in spheroplasts obtained from Candida albicans control strain ATCC 90028 by lyticase treatment. Mitochondria in situ were able to phosphorylate externally added ADP (200 microM) in the presence of 0.05% BSA. Mitochondria in situ generated and sustained stable mitochondrial Deltapsi respiring on 5 mM NAD-linked substrates, 5 mM succinate, or 100 microM N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride plus 1 mM ascorbate. Rotenone (4 microM) inhibited respiration by 30% and 2 micro M antimycin A or myxothiazole and 1 mM cyanide inhibited it by 85%. Cyanide-insensitive respiration was partially blocked by 2 mM benzohydroxamic acid, suggesting the presence of an alternative oxidase. Candida albicans mitochondria in situ presented a carboxyatractyloside-insensitive increase of Deltapsi induced by 5 mM ATP and 0.5% BSA, and Deltapsi decrease induced by 10 microM linoleic acid, both suggesting the existence of an uncoupling protein. The presence of this protein was subsequently confirmed by immunodetection and respiration experiments with isolated mitochondria. In conclusion, Candida albicans ATCC 90028 possesses an alternative electron transfer chain and alternative oxidase, both absent in animal cells. These pathways can be exceptional targets for the design of new chemotherapeutic agents. Blockage of these respiratory pathways together with inhibition of the uncoupling protein (another potential target for drug design) could lead to increased production of reactive oxygen species, dysfunction of Candida mitochondria, and possibly to oxidative cell death.371455-6

    Deposition of tin oxide, iridium and iridium oxide films by metal-organic chemical vapor deposition for electrochemical wastewater treatment

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    In this research, the specific electrodes were prepared by metal-organic chemical vapor deposition (MOCVD) in a hot-wall CVD reactor with the presence of O2 under reduced pressure. The Ir protective layer was deposited by using (Methylcyclopentadienyl) (1,5-cyclooctadiene) iridium (I), (MeCp)Ir(COD), as precursor. Tetraethyltin (TET) was used as precursor for the deposition of SnO2 active layer. The optimum condition for Ir film deposition was at 300 °C, 125 of O2/(MeCp)Ir(COD) molar ratio and 12 Torr of total pressure. While that of SnO2 active layer was at 380 °C, 1200 of O2/TET molar ratio and 15 Torr of total pressure. The prepared SnO2/Ir/Ti electrodes were tested for anodic oxidation of organic pollutant in a simple three-electrode electrochemical reactor using oxalic acid as model solution. The electrochemical experiments indicate that more than 80% of organic pollutant was removed after 2.1 Ah/L of charge has been applied. The kinetic investigation gives a two-step process for organic pollutant degradation, the kinetic was zero-order and first-order with respect to TOC of model solution for high and low TOC concentrations, respectively

    Photonic Sampling of Broadband Qam Microwave Signals Exploiting Interleaved Optical Nyquist Pulses

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    We performed photonic sampling of 6 Gbaud 16-QAM signals at 20 GHz sampling frequency by interleaving and time-aligning two 10 GHz Nyquist optical sampling pulse trains using a SMF as the dispersive medium

    Draft of Cheyenne & Arapahoe Report

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    https://digitalcommons.assumption.edu/mallet-manuscripts/1030/thumbnail.jp

    Search for the exotic Θ+\Theta^+ resonance in the NOMAD experiment

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    A search for exotic Theta baryon via Theta -> proton +Ks decay mode in the NOMAD muon neutrino DIS data is reported. The special background generation procedure was developed. The proton identification criteria are tuned to maximize the sensitivity to the Theta signal as a function of xF which allows to study the Theta production mechanism. We do not observe any evidence for the Theta state in the NOMAD data. We provide an upper limit on Theta production rate at 90% CL as 2.13 per 1000 of neutrino interactions.Comment: Accepted to European Physics Journal

    Production properties of K*(892) vector mesons and their spin alignment as measured in the NOMAD experiment

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    First measurements of K*(892) mesons production properties and their spin alignment in nu_mu charged current (CC) and neutral current (NC) interactions are presented. The analysis of the full data sample of the NOMAD experiment is performed in different kinematic regions. For K*+ and K*- mesons produced in nu_mu CC interactions and decaying into K0 pi+/- we have found the following yields per event: (2.6 +/- 0.2 (stat.) +/- 0.2 (syst.))% and (1.6 +/- 0.1 (stat.) +/- 0.1 (syst.))% respectively, while for the K*+ and K*- mesons produced in nu NC interactions the corresponding yields per event are: (2.5 +/- 0.3 (stat.) +/- 0.3 (syst.))% and (1.0 +/- 0.3 (stat.) +/- 0.2 (syst.))%. The results obtained for the rho00 parameter, 0.40 +/- 0.06 (stat) +/- 0.03 (syst) and 0.28 +/- 0.07 (stat) +/- 0.03 (syst) for K*+ and K*- produced in nu_mu CC interactions, are compared to theoretical predictions tuned on LEP measurements in e+e- annihilation at the Z0 pole. For K*+ mesons produced in nu NC interactions the measured rho00 parameter is 0.66 +/- 0.10 (stat) +/- 0.05 (syst).Comment: 20 p

    Prediction of Neutrino Fluxes in the NOMAD Experiment

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    The method developed for the calculation of the flux and composition of the West Area Neutrino Beam used by NOMAD in its search for neutrino oscillations is described. The calculation is based on particle production rates computed using a recent version of FLUKA and modified to take into account the cross sections measured by the SPY and NA20 experiments. These particles are propagated through the beam line taking into account the material and magnetic fields they traverse. The neutrinos produced through their decays are tracked to the NOMAD detector. The fluxes of the four neutrino flavours at NOMAD are predicted with an uncertainty of about 8% for nu(mu) and nu(e), 10% for antinu(mu), and 12% for antinu(e). The energy-dependent uncertainty achieved on the R(e, mu) prediction needed for a nu(mu)->nu(e) oscillation search ranges from 4% to 7%, whereas the overall normalization uncertainty on this ratio is 4.2%.Comment: 43 pages, 20 figures. Submitted to Nucl. Phys.
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