60 research outputs found

    Determination of Interval Depth of Subsurface Layers by Velocity Analysis of Seismic Reflection Data, in Part of Niger Delta Basin, Nigeria

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    Seismic reflection data obtained from 3 – D survey in part of the Niger delta basin, Nigeria was processed using Velocity Computation (VELCOM), an interactive velocity analysis interpretation program. The application uses the principle of Apparent Velocity Picking, Normal Moveout (NMO) Correction and Stacking. Velocity intervals and stacking velocity for 8 Common Depth Points (CDPs) were obtained. Interval velocity ranges between 1814 - 5579 ms-1 and Stacking velocity (Vs) ranges between 1814 – 3639 ms-1. Both velocities increase with depth, with interval velocity more steeply than Stacking velocity within the same interval depth. The corresponding depths to the reflecting surfaces, ranging from 554 – 10033m, were obtained, which led to the interval depths of layers ranging from 31 – 1180m. The result of this velocity analysis can be applied in NMO correction, calculating depths from reflection times, horizons identifications, the recognitions of lithology, detection of high pressure zone and migration. Keywords: Seismic reflection, Normal move -out, Velocity, Depth of laye

    Natural Variation in Arabidopsis Cvi-0 Accession Reveals an Important Role of MPK12 in Guard Cell CO2 Signaling

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    Author Summary Human activities have increased the concentrations of CO2 and harmful air pollutants such as ozone in the troposphere. These changes can have detrimental consequences for agricultural productivity. Guard cells, which form stomatal pores on leaves, regulate plant gas exchange. To maintain photosynthesis, stomata open to allow CO2 uptake, but at the same time, open stomata lead to loss of water and allow the entrance of ozone. Elevated atmospheric CO2 levels reduce stomatal apertures, which can improve plant water balance but also increases leaf temperature. Using genetic approaches—in which we exploit natural variation and mutant analysis of thale cress (Arabidopsis thaliana)—we find that MITOGEN-ACTIVATED PROTEIN KINASE 12 (MPK12) and its inhibitory interaction with another kinase, HIGH LEAF TEMPERATURE 1 (HT1) (involved in guard cell CO2 signaling), play a key role in this regulatory process. We have therefore identified a mechanism in which guard cell CO2 signaling regulates how efficiently plants use water and cope with the air pollutant ozone.Peer reviewe

    Immunoglobulin deficiencies and susceptibility to infection among homozygotes and heterozygotes for C2 deficiency

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    About 25% of C2-deficient homozygotes have increased susceptibility to severe bacterial infections. C2-deficient homozygotes had significantly lower serum levels of IgG2, IgG4, IgD, and Factor B, significantly higher levels of IgA and IgG3 and levels of IgG1 and IgM similar to controls. Type I ( 28 bp deletion in C2 exon 6 on the [HLA-B18, S042, DR2] haplotype or its fragments) and type II ( non-type I) C2-deficient patients with increased susceptibility to bacterial infection had significantly lower mean levels of IgG4 ( p < 0.04) and IgA ( p < 0.01) than those without infections ( who had a higher than normal mean IgA level) but similar mean levels of other immunoglobulins and Factor B. Of 13 C2-deficient homozygotes with infections, 85% had IgG4 deficiency, compared with 64% of 25 without infections. IgD deficiency was equally extraordinarily common among infection-prone (50%) and noninfection-prone (70%) homozygous type I C2-deficient patients. IgD deficiency was also common (35%) among 31 type I C2-deficient heterozygotes ( with normal or type II haplotypes), but was not found in 5 type II C2-deficient heterozygotes or 1 homozygote. Thus, C2 deficiency itself is associated with many abnormalities in serum immunoglobulin levels, some of which, such as in IgG4 and IgA, may contribute to increased susceptibility to infection. In contrast, IgD deficiency appears not to contribute to increased infections and appears to be a dominant trait determined by a gene or genes on the extended major histocompatibility complex (MHC) haplotype [HLA-B18, S042, DR2] ( but probably not on type II C2-deficient haplotypes) similar to those previously identified on [HLA-B8, SC01, DR3] and [HLA-B18, F1C30, DR3]

    Local vanadium release from a calcium sulfate carrier accelerates fracture healing.

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    This study evaluated the efficacy of using calcium sulfate (CaSO4 ) as a carrier for intramedullary delivery of an organic vanadium salt, vanadyl acetylacetonate (VAC) after femoral fracture. VAC can act as an insulin-mimetic and can be used to accelerate fracture healing in rats. A heterogenous mixture of VAC and CaSO4 was delivered to the fracture site of BB Wistar rats, and mechanical testing, histomorphometry, micro-computed tomography (micro-CT) were performed to measure healing. At 4 weeks after fracture, maximum torque to failure, effective shear modulus, and effective shear stress were all significantly higher (p \u3c 0.05) in rats treated with 0.25 mg/kg VAC-CaSO4 as compared to carrier control rats. Histomorphometry found a 71% increase in percent cartilage matrix (p \u3c 0.05) and a 64% decrease in percent mineralized tissue (p \u3c 0.05) at 2 weeks after fracture in rats treated with 0.25 mg/kg of VAC-CaSO4 . Micro-CT analyses at 4 weeks found a more organized callus structure and higher trending maximum connected z-ray. fraction for VAC-CaSO4 groups. Evaluation of radiographs and serial histological sections at 12 weeks did not show any evidence of ectopic bone formation. As compared to previous studies, CaSO4 was an effective carrier for reducing the dose of VAC required to accelerate femoral fracture healing in rats
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