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Ordered Pattern (ordered + pattern)
Selected AbstractsSelf-Assembly of Ordered Patterns: Stressed Triangular Tessellations and Fibonacci Parastichous Spirals on Ag Core/SiO2 Shell Microstructures (Adv. Mater.ADVANCED MATERIALS, Issue 45 200945/2009) Stress engineering offers an effective route for self-assembly of ordered patterns. By stressing Ag core/SiO2 shell microstructures, spontaneous occurrence of triangular tessellations and Fibonacci parastichous spirals can be observed on the spherical and conical cores and shells, respectively. On p. 4652, Ze-Xian Cao and co-workers demonstrate that the stressed patterns are an immediate response to the geometry of the shrinking core/shells. The reproduction of Fibonacci spirals, ubiquitous in the world of plants, on the surface of totally inorganic microstructures provides strong confirmation of the mechanical principle of phyllotaxis. [source] Does Imiquimod Histologically Rejuvenate Ultraviolet Radiation,Damaged Skin?DERMATOLOGIC SURGERY, Issue 12 2007KATHLEEN SMITH MD BACKGROUND Imiquimod (IMI) 5% is believed by some to result in an improved cosmetic appearance of chronically ultraviolet radiation (UV)-damaged skin. OBJECTIVE The objective was to determine what histologic and immunohistologic changes were present in actinically damaged skin after treatment with IMI. METHODS AND MATERIALS Pre- and posttherapy biopsies of 12 patients with histories of actinic keratoses were evaluated with routine histology and immunohistochemical stains including p53, p63, proliferating cell nuclear antigen (PCNA), c-kit, and Factor XIIIa. RESULTS After IMI therapy there was less compact hyperkeratosis, a more uniform rete ridge pattern with a more ordered proliferation of the epidermis, and a decrease in sun-damaged melanocytes. The papillary dermis showed a more uniform cellularity, and there was increased cellularity within the area of solar elastosis. After therapy, staining for p53, p63, and PCNA was decreased within the epidermis; staining for c-kit was decreased but more uniform in the basal cell; and Factor XIIIa expression was increased within the papillary dermis with a more ordered pattern of staining. CONCLUSION These morphologic and immunohistochemical patterns may explain some of the improvement in overall skin appearance after IMI therapy and may be related to the spectrum of signaling pathways induced by the imidazoquinolines. [source] Clonal analysis of patterns of growth, stem cell activity, and cell movement during the development and maintenance of the murine corneal epitheliumDEVELOPMENTAL DYNAMICS, Issue 4 2002J. Martin Collinson Abstract Patterns of growth and cell movement in the developing and adult corneal epithelium were investigated by analysing clonal patches of LacZ -expressing cells in chimeric and X-inactivation mosaic mice. It was found that cell proliferation throughout the basal corneal epithelium during embryogenesis and early postnatal life creates a disordered mosaic pattern of LacZ+ clones that contrasts with patterns of proliferation and striping produced during the later embryonic stages of retinal pigmented epithelium development. The early mosaic pattern in the corneal epithelium is replaced in the first 12 postnatal weeks by an ordered pattern of radial stripes or sectors that reflects migration without mixing of the progeny of clones of limbal stem cells. In contrast to previous assumptions, it was found that maturation of the activity of limbal stem cells and the pattern of migration of their progeny are delayed for several weeks postnatally. No evidence was found for immigration of the progeny of stem cells until the 5th postnatal week. There are approximately 100 clones of limbal stem cells initially, and clones are lost during postnatal life. Our studies provide a new assay for limbal and corneal defects in mutant mice. © 2002 Wiley-Liss, Inc. [source] EXHAUSTION OF MORPHOLOGIC CHARACTER STATES AMONG FOSSIL TAXAEVOLUTION, Issue 2 2000Peter J. Wagner Abstract., Frequencies of new character state derivations are analyzed for 56 fossil taxa. The hypothesis that new character states are added continuously throughout clade history can be rejected for 48 of theses clades. Two alternative explanations are considered: finite states and ordered states. The former hypothesizes a limited number of states available to each character and is tested using rarefaction equations. The latter hypothesizes that there are limited possible descendant morphologies for any state, even if the character has infinite potential states. This is tested using power functions. The finite states hypothesis explains states: steps relationships significantly better than does the ordered states hypothesis in 14 cases; the converse is true for 14 other cases. Under either hypothesis, trilobite clades show appreciably more homoplasy after the same numbers of steps than do molluscs, echinoderms, or vertebrates. The prevalence of the exhaustion pattern among different taxonomic groups implies that worker biases are not to blame and instead implicates biological explanations such as intrinsic constraints or persistent selective trends. Regardless of the source of increased homoplasy, clades appear to exhaust their available character spaces. Nearly all examined taxa show significant increases in proportions of incompatible character pairs (i.e., those necessarily implying homoplasy) as progressively younger taxa are added to character matrices. Thus, a deterioration of hierarchical structure accompanies character state exhaustion. Exhaustion has several implications: (1) the basic premise of cladistic analyses (i.e., that maximum congruence reflects homology rather than homoplasy) becomes increasingly less sound as clades age; (2) sampling high proportions of taxa probably is needed for congruence to discern homoplasy from homology; (3) stratigraphic data might be necessary to discern congruent homoplasy from congruent homology; and (4) in many cases, character states appear to have evolved in ordered patterns. [source] Self-Assembly of Ordered Patterns: Stressed Triangular Tessellations and Fibonacci Parastichous Spirals on Ag Core/SiO2 Shell Microstructures (Adv. Mater.ADVANCED MATERIALS, Issue 45 200945/2009) Stress engineering offers an effective route for self-assembly of ordered patterns. By stressing Ag core/SiO2 shell microstructures, spontaneous occurrence of triangular tessellations and Fibonacci parastichous spirals can be observed on the spherical and conical cores and shells, respectively. On p. 4652, Ze-Xian Cao and co-workers demonstrate that the stressed patterns are an immediate response to the geometry of the shrinking core/shells. The reproduction of Fibonacci spirals, ubiquitous in the world of plants, on the surface of totally inorganic microstructures provides strong confirmation of the mechanical principle of phyllotaxis. [source] | ||||||||||