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Zone B (zone + b)

Distribution by Scientific Domains
Medical Sciences60%

Terms modified by Zone B

  • zone b cell
    		•

    Selected Abstracts

    Evolution of an accretionary complex along the north arm of the Island of Sulawesi, Indonesia

    ISLAND ARC, Issue 1 2004
    Yusuf Surachman Djajadihardja
    Abstract Seismic reflections across the accretionary prism of the North Sulawesi provide excellent images of the various structural domains landward of the frontal thrust. The structural domain in the accretionary prism area of the North Sulawesi Trench can be divided into four zones: (i) trench area; (ii) Zone A; (iii) Zone B; and (iv) Zone C. Zone A is an active imbrication zone where a decollement is well imaged. Zone B is dominated by out-of-sequence thrusts and small slope basins. Zone C is structurally high in the forearc basin, overlain by a thick sedimentary sequence. The subducted and accreted sedimentary packages are separated by the decollement. Topography of the oceanic basement is rough, both in the basin and beneath the wedge. The accretionary prism along the North Sulawesi Trench grew because of the collision between eastern Sulawesi and the Bangai,Sula microcontinent along the Sorong Fault in the middle Miocene. This collision produced a large rotation of the north arm of Sulawesi Island. Rotation and northward movement of the north arm of Sulawesi may have resulted in southward subduction and development of the accretionary wedge along North Sulawesi. Lateral variations are wider in the western areas relative to the eastern areas. This is due to greater convergence rates in the western area: 5 km/My for the west and 1.5 km/My for the east. An accretionary prism model indicates that the initiation of growth of the accretionary prism in the North Sulawesi Trench occurred approximately 5 Ma. A comparison between the North Sulawesi accretionary prism and the Nankai accretionary prism of Japan reveals similar internal structures, suggesting similar mechanical processes and structural evolution. [source]

    Recruitment and selection of marginal zone B,cells is independent of exogenous antigens

    EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2005
    Peter
    Abstract Marginal zone B (MZ-B) cells of the spleen contribute significantly to the immunity against invasive infections with polysaccharide-encapsulated bacteria. Recent evidence indicates that recruitment and selection of MZ-B,cells occurs on the basis of positive selection constraints that likely operate via B,cell receptor (BCR) signaling. Previous studies have shown that MZ-B,cells carry relatively shorter immunoglobulin (Ig) heavy (H) chain complementarity-determining region,3 (H-CDR3) sequences and express BCR which are thought to be polyreactive. In this scenario, MZ-B,cell selection proceeds via engagement of the BCR with exogenous (i.e. microbial gut flora-derived) and/or endogenous (self) antigens. Here, we studied the influence of exogenous antigens on the selection process of MZ-B,cells using non-genetically manipulated adult germ-free and conventionally reared infant rats. This study was carried out by H-CDR3 spectratype analysis of VH(PC7183)-encoded Ig VHDJH -, transcripts expressed by purified splenic MZ-B,cells and other B,cell subsets. We show that MZ-B,cells in both adult germ-free and conventionally reared infant (14-day-old) rats are H-CDR3-selected cells, providing strong evidence that recruitment and selection of MZ-B,cells is driven by self antigens. [source]

    Fault configuration produced by initial arc rifting in the Parece Vela Basin as deduced from seismic reflection data

    ISLAND ARC, Issue 3 2007
    Mikiya Yamashita
    Abstract The Parece Vela Basin (PVB), which is a currently inactive back-arc basin of the Philippine Sea Plate, was formed by separation between the Izu-Ogasawara Arc (IOA) and the Kyushu-Palau Ridge (KPR). Elucidating the marks of the past back-arc opening and rifting is important for investigation of its crustal structure. To image its fault configurations and crustal deformation, pre-stack depth migration to multichannel seismic reflection was applied and data obtained by the Japan Agency for Marine-Earth Science and Technology and Metal Mining Agency of Japan and Japan National Oil Corporation (Japan Oil, Gas and Metals National Corporation). Salient results for the pre-stack depth-migrated sections are: (i) deep reflectors exist around the eastern margin of KPR and at the western margin of IOA down to 8 km depth; and (ii) normal fault zones distributed at the eastern margin of the KPR (Fault zone A) and the western margin of the IOA (Fault zone B) have a total displacement of greater than 500 m associated with synrift sediments. Additional normal faults (Fault zone C) exist 20 km east of the Fault zone B. They are covered with sediment, which indicates deposition of recent volcanic products in the IOA. According to those results: (i) the fault displacement of more than 500 m with respect to initial rifting was approximately asymmetric at 25 Ma based on PSDM profiles; and (ii) the faults had reactivated after 23 Ma, based on the age of deformed sediments obtained from past ocean drillings. The age of the base sediments corresponds to those of spreading and rotation after rifting in the PVB. Fault zone C is covered with thick and not deformed volcanogenic sediments from the IOA, which suggests that the fault is inactive. [source]

    Orthodontic movement in bone defects augmented with Bio-OssŪ

    JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 1 2001
    An experimental study in dogs
    Abstract Objective: To study if it was possible to move, by orthodontic means, a tooth into an area of the jaw that had been augmented with Bio-OssŪ. Material and Methods: 5 beagle dogs were used. The 1st, 2nd, and 4th mandibular premolars on each side were removed. The defect at the left 4th premolar site was filled with a biomaterial (Bio-OssŪ) while the corresponding defect in the right side was left for spontaneous healing. 3 months later, an orthodontic device was inserted in each side of the mandible. The device was designed to allow distal, bodily movement of the 3rd premolars. When the experimental teeth had been moved into the extraction sites of the 4th premolars, the animals were sacrificed and biopsies of the premolar-molar regions of the mandible sampled. The tissues were prepared for histological analysis using standard procedures. In the sections, 3 zones were identified: zone A=the bone tissue within the distal portion of the previous extraction site (4th premolar), zone B=the pressure side of the 3rd premolar, zone C=the tension side of the 3rd premolar. The area occupied by mineralized bone, Bio-OssŪ particles and bone marrow was determined by a point counting procedure. The width of the periodontal ligament as well as the percentage of the root surface (in zone B) that exhibited resorption was determined. Results: The findings demonstrated that it was possible to move a tooth into an area of an alveolar ridge that 3 months previously had been augmented with a biomaterial. It was also demonstrated that 12 months after grafting, Bio-OssŪ particles remained as inactive filler material in the not utilized part of zone A. The biomaterial was not present in zone C but present in small amounts in zone B. Conclusion: During the orthodontic tooth movement the graft material (Bio-OssŪ) was degraded and eliminated from the part of the alveolar ridge that was utilized for the experiment. In the non-utilized part of the ridge the biomaterial, however, remained as a seemingly inactive filler material. [source]