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Surface Irregularities (surface + irregularity)
Selected AbstractsStochastic Response of a Continuous System with Stochastic Surface Irregularities to an Accelerated LoadPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003C.A. Schenk The problem of calculating the second moment characteristics of the response of a general class of nonconservative linear distributed parameter systems with stochastically varying surface roughness, excited by a moving concentrated load, is investigated. In particular the case of an accelerated load is discussed. The surface roughness is modeled as a Gaussian stationary second order process. For the stochastic representation of the surface roughness a orthogonal series expansion of the covariance kernel, the so called Karhunen-Loéve expansion, is applied. The resulting initial/boundary value problem is transformed by eigenfunction expansion into the modal state space. Second moment characteristics of the response are determined numerically by direct integration using a Runge-Kutta method. [source] Roughness Characterization through 3D Textured Image Analysis: Contribution to the Study of Road Wear LevelCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 2 2004M. Khoudeir The microtexture is defined as surface irregularities whose height ranges from 0.001 mm to 0.5 mm and whose width is less than 0.5 mm (Alvarez and Mprel, 1994). The deterioration due to the road traffic, especially polishing effect, involves a change in the microtexture. So, we suggest a method to characterize, through image analysis, wear level or microroughness of road surfaces. We propose then, on one hand a photometric model for road surface, and, on the other hand, a geometrical model for road surface profile. These two models allow us to develop roughness criteria based on the study of the statistical properties of: the distribution of the gray levels in the image, the distribution of the absolute value of its gradient, the form of its autocorrelation function, and the distribution of its curvature map. Experiments have been done with images of laboratory-made road specimens at different wear levels. The obtained results are similar to those obtained by a direct method using road profiles. [source] "Tongue sandwich" bolster for skin graft immobilization,HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 7 2002Charles E. Butler MD Abstract Background Because of surface irregularities and continuous movement of the tongue, predictable immobilization of split-thickness skin grafts (STSGs) for tongue defects is difficult to achieve. Methods A novel composite, bilayer foam bolster was used to immobilize a STSG after reconstruction of more than 80% of the tongue mucosa after resection of a squamous cell carcinoma and extensive leukoplakia. Dorsal and ventral bolster components were placed over the STSG and affixed using transglossal, through-and-through sutures. Results The composite foam bolster provided uniform compression along the highly irregular and mobile skin-grafted surface. Graft survival was excellent, and there were no complications. Conclusions The "tongue sandwich" bolster is quickly and easily fabricated, immobilizes the tongue in a fully expanded position, and provides excellent apposition of STSGs to highly irregular and vascular surfaces. © 2002 Wiley Periodicals, Inc. Head Neck 24: 705,709, 2002 [source] ROLE OF SURFACE WOUNDS AND BROWN ALGAL EPIPHYTES IN THE COLONIZATION OF ASCOPHYLLUM NODOSUM (PHAEOPHYCEAE) FRONDS BY VERTEBRATA LANOSA (RHODOPHYTA),JOURNAL OF PHYCOLOGY, Issue 3 2009Caroline M. Longtin Ascophyllum nodosum (L.) Le Jol. forms extensive beds in wave-sheltered, rocky intertidal habitats on the northwestern Atlantic coast. This fucoid seaweed is host to an obligate red algal epiphyte, Vertebrata lanosa (L.) T. A. Chr. [=Polysiphonia lanosa (L.) Tandy], and two facultative brown algal epiphytes, Elachista fucicola (Velley) Aresch. and Pylaiella littoralis (L.) Kjellm. Although V. lanosa can occur throughout most of the length of host fronds, it largely predominates in midfrond segments. The two brown algal epiphytes are restricted to distal segments. Through field experiments conducted in Nova Scotia, Canada, we tested the hypothesis that surface wounds are required for the colonization of distal segments of host fronds by V. lanosa. Distal tissues normally have a smooth surface because of their young age (A. nodosum fronds grow apically). By creating small wounds that mimicked grazing wounds distributed elsewhere on host fronds, we demonstrated that V. lanosa can colonize distal frond segments during the growth and reproductive season (summer and autumn). Approximately half of the artificial wounds were colonized by V. lanosa during this time. The experimental exclusion of both brown algal epiphytes from distal frond segments did not affect colonization by V. lanosa. Thus, we conclude that the absence of surface irregularities on distal segments of host fronds, specifically small wounds, is the main factor explaining the absence of V. lanosa there. We propose that further experimental work clarifying epiphyte distribution in host beds will enhance our ability to understand the functional role of epiphytes in intertidal ecosystems. [source] Stroma remodelling during healing of corneal surface irregularities induced by PTKACTA OPHTHALMOLOGICA, Issue 4 2007Marios Panagiotopoulos Abstract. Purpose:, To study the histopathology of the remodelling process in the stroma after excimer-laser-induced corneal irregular injuries. Methods:, Seven New Zealand white rabbits received in one eye a transepithelial plano photoablation (60 µm) and an additional plano ablation (25 µm). On the denuded stroma, an electron microscopy specimen grid was placed and another 25 µm ablation was applied to produce surface irregularities. Dichlorotriazinyl aminofluorescein (DTAF) was then applied for 45 seconds. Another seven right eyes of seven rabbits were ablated the same way but without using the grid, resulting in a plano ablation. All the rabbits were killed at weekly intervals after treatment. The harvested corneas from both eyes were further processed for haematoxylin-eosin staining and were also stained with monoclonal antibodies directed against Ki-67 antigen and ,-smooth muscle actin (,-SMA). All specimens were examined under light and fluorescence microscope. Results:, The corneal wounds were covered by epithelium during the first week. The 25 µm × 25 µm × 25 µm stromal irregularities were clearly discernible up to 3 weeks after treatment, during which time they melted and disappeared. A homogeneous zone was formed in which stroma cells laid down an initially disorganized stroma. This was sharply visible under a fluorescence microscope as a dark area between the dichlorotriazinyl aminofluorescein (DTAF) fluorescent stroma and autofluorescent epithelium. Very little response was seen in the plano-ablated wound microscopically and in terms of positive stained cells. Conclusion:, As the irregularities are flattened and the homogenous zone becomes repopulated with keratocytes forming extracellular matrix material (ECM), the cornea regains its previous architecture in both groups. The irregular wound surface promotes wound-healing reactivity, a process that allows the cornea to compensate for the irregularities and heal to a functional state. [source] Wound healing response in the presence of stromal irregularities after excimer laser treatmentACTA OPHTHALMOLOGICA, Issue 4 2001Beat A. Weber ABSTRACT. Purpose: To trace the fate of stromal irregularities after excimer laser treatment and to increase our knowledge of the reasons why surface irregularities in the ablation bed cause inferior postoperative results. Methods: Twelve New Zealand White rabbits received a transepithelial photoablation to a preset depth of 60 ,m. An electron microscopy specimen grid was then placed on the denuded stroma and another 20 ,m ablation was applied in order to produce surface irregularities. Another six rabbits received a plano transepithelial photoablation to a preset depth of 80 ,m. The treated corneas were harvested at various timepoints and differentially further processed for microradiography, hematoxylin-eosin -, hyaluronan (HA)- and leukocyte protein L1 staining. Results: In the grid treated corneas the subepithelial mesh pattern is clearly discernible after 1 week, and after 4 weeks it is replaced by a subepithelial layer containing HA and water. The thinning of this layer between 1 and 12 weeks is statistically significant (p<0.05). After 4 and 8 week the plano treated corneas only exhibit some subepithelial HA- and water accumulation. After 1 day the grid treated corneas show an extensive stromal infiltration of leukocytes. In the plano treated corneas the leukocytes mainly remain on the surface. Conclusions: During the healing process stromal irregularities are flattened, leaving a homogeneous zone with increased water content. This subepithelial layer is rarefying as new subepithelial tissue is forming. Postablational irregularities induce a more pronounced healing reaction when compared to a smooth ablation surface. Leukocyte infiltration seems to play a role in this process. [source] The latest cosmeceutical approaches for anti-agingJOURNAL OF COSMETIC DERMATOLOGY, Issue 2007Zoe Diana Draelos MD Summary Background, Cosmeceuticals provide a new therapeutic frontier for anti-aging in dermatology. The most dramatic signs of cutaneous aging include the lack of skin surface regularity, the formation of rhagades, and the increased presence of dyspigmentation. Background, The objective of this review is to illustrate how these three needs of maturing skin can be met by novel ingredients incorporated into carefully constructed formulations designed to deliver scientifically measurable and visibly noticeable improvement. Conclusion, Skin surface irregularity can be improved through increased skin turnover facilitated by topical niacinamide, while the appearance of fine lines can be diminished through the application of moisturizers containing engineered peptides and over-the-counter retinoids, such as retinyl propionate. Finally, skin pigmentation can become more regular with the topical application of N-acetyl glucosamine and ultraviolet A photoprotective ingredients. Furthermore, combining cosmeceutical ingredients in a moisturizing vehicle can magnify benefits and profoundly improve skin appearance. [source] | |||||||||||||