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Wall Boundaries (wall + boundary)

Distribution by Scientific Domains
Medical Sciences50%

Terms modified by Wall Boundaries

  • wall boundary condition
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    Selected Abstracts

    Seed morphology of some species of Convolvulaceae from Egypt (Identification of species and systematic significance)

    FEDDES REPERTORIUM, Issue 1-2 2007
    K. Abdel Khalik
    Seed morphology of 31 taxa belong to six genera of Convolvulaceae from Egypt were examined by using light and scanning electron microscopy. Macro- and micromorphological characters, including seed shape, colour, size, surface, epidermal cell shape, anticlinal boundaries, outer periclinal cell wall and relief of outer cell walls, are presented. Three types of basic anticlinal cell wall boundaries and three types of relief outer cell walls are recognized and four different shapes of the outer periclinal cell wall are described. A key for the identification of the investigated taxa based on seed characters is provided. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Morphologie der Samen einiger Arten der Convolvulaceae aus Ägypten (Bestimmung von Arten und systematische Bedeutung) Unter Anwendung von Licht- und Elektronenmikroskopie wurde die Morphologie der Samen von 31 Arten aus sechs Gattungen der Convolvulaceae untersucht. Berücksichtigt wurden die makro- und mikromorphologischen Merkmale der Samen umfassend äußere Form, Farbe, Größe, Oberfläche, Form der Epidermiszellen, antiklinale und periklinale Zellwände und Relief der äußeren Zellwände. Drei Typen basaler antiklinaler Zellwände und drei Typen des Reliefs der äußeren Zellwände wurden nachgewiesen; ferner werden vier Formen der äußeren periklinalen Zellwände beschrieben. Ein Schlüssel zur Bestimmung der untersuchten Taxa auf der Basis der Merkmale der Samen wird vorgelegt. [source]

    Seed morphology of Cuscuta L. (Convolvulaceae) in Egypt and its systematic significance

    FEDDES REPERTORIUM, Issue 3-4 2006
    K. N. Abdel Khalik
    The seed morphology of eight taxa of Cuscuta from Egypt has been studied using light and scanning electron microscopy, to determine the significance of seed coat features as taxonomic characters. Macro- and micromorphological characters, including seed shape, colour, size, epidermal cell shape, anticlinal boundaries, outer periclinal cell wall and relief of outer cell walls are presented. Three types of anticlinal cell wall boundaries are recognized and two different shapes of outer periclinal cell wall are described. The secondary sculpture of the cell wall varies from striate to micro-reticulate, and smooth to fine folds. A key for the identification of the investigated taxa based on seed characters is provided. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Samenmorphologie von Cuscuta L. (Convolvulaceae) in Ägypten und ihre systematische Bedeutung Die Morphologie des Samens von acht ägyptischen Cuscuta -Taxa wurde mittels Licht- und Elektronenmikroskopie untersucht, um die Bedeutung der Merkmale der Samenschale für die Taxonomie zu ermitteln. Makro- und mikromorphologische Merkmale einschließlich Samengestalt, Farbe, Größe, Form der Epidermiszellen, antiklinale Zellwände, äußere Periklinal-Zellwände und Relief der äußeren Zellwände umfassend, wurden untersucht. Drei Typen antiklinaler Zellwand-Umrisse und zwei unterschiedliche Formen der äußeren Periklinal-Zellwände werden beschrieben. Die sekundäre Skulptur der Zellwände variiert von striat bis mikro-reticulat, und von glatt zu leicht gefaltet. Ein Bestimmungsschlüssel basierend auf den Samenmerkmalen der untersuchten Sippen wird vorgelegt. [source]

    Effect of black blood MR image quality on vessel wall segmentation

    MAGNETIC RESONANCE IN MEDICINE, Issue 2 2001
    Jonathan B. Thomas
    Abstract Black blood MRI has become a popular technique for measuring arterial wall area as an indicator of plaque size. Computer-assisted techniques for segmenting vessel boundaries have been developed to increase measurement precision. In this study, the carotid arteries of four normal subjects were imaged at seven different fields of view (FOVs), keeping all other imaging parameters fixed, to determine whether spatial resolution could be increased at the expense of image quality without sacrificing precision. Wall areas were measured via computer-assisted segmentation of the vessel boundaries performed repeatedly by two operators. Analysis of variance (ANOVA) demonstrated that the variability of wall area measurements was below 1.5 mm2 for in-plane spatial resolutions between 0.22 mm and 0.37 mm. An inverse relationship between operator variability and the signal difference-to-noise ratio (SDNR) demonstrated that semi-automatic segmentation of the wall boundaries was robust for SDNR >3, defining a criterion above which subjective image quality can be degraded without an appreciable loss of information content. Our study also suggested that spatial resolutions higher than 0.3 mm may be required to quantify normal wall areas to within 10% accuracy, but that the reduced SNR associated with the higher resolution may be tolerated by semi-automated wall segmentation without an appreciable loss of precision. Magn Reson Med 46:299,304, 2001. © 2001 Wiley-Liss, Inc. [source]

    MRI of early- and late-stage arterial remodeling in a low-level cholesterol-fed rabbit model of atherosclerosis

    JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2007
    John A. Ronald MS
    Abstract Purpose To monitor early- and late-stage arterial remodeling following low-level cholesterol (CH) feeding in rabbits using a standardized MRI protocol. Materials and Methods New Zealand White rabbits were fed a CH diet (0.25% w/w) (n = 15) or normal chow (n = 6) and imaged either at 0, 2, 6, 8, and 11 months ("early-stage") or 12, 14, 16, 18, and 20 months ("late-stage"). T2-weighted fast-spin-echo images (,200 ,m in-plane resolution) of aortic lesions were collected using either a 1.5 or 3.0T MR scanner interfaced with a customized surface RF coil. Luminal (LA), outer vessel wall boundary (OVBA), and vessel wall areas (VWA) were assessed. Results Among CH-fed animals in the early-stage group, increased VWA associated with decreased OVBA and a more pronounced decrease in LA was first detectable at 8 months. These changes became more evident between 8 and 11 months. In the late-stage group, lesions continued to grow in response to CH-feeding, as VWA significantly increased at regular 2-month intervals. Beyond 16 months, signal intensity differences (reflecting increased lesion complexity) within the vessel wall were noted. Conclusion This often-overlooked rabbit model combined with customized MR technology holds tremendous promise for studying the natural progression, regression, and remodeling of atherosclerotic lesions. J. Magn. Reson. Imaging 2007;26:1010,1019. © 2007 Wiley-Liss, Inc. [source]