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Abrasion
Terms modified by Abrasion Selected AbstractsLetter: The Superiority of Dermabrasion over Laser Abrasion in the Prophylaxis of Malignant and Premalignant DiseaseDERMATOLOGIC SURGERY, Issue 2 2007FIACS, LAWRENCE M. FIELD MD No abstract is available for this article. [source] Laboratory simulation of clast abrasionEARTH SURFACE PROCESSES AND LANDFORMS, Issue 2 2002J. Lewin Abstract Experimental abrasion of river-bed materials has been widely undertaken, producing ,downstream' fining rates that generally are believed to be much less than those observed in the field. A conclusion commonly adopted has been that sorting processes are more effective than abrasion processes. A comparative evaluation of results from an abrasion tank and a tumbling barrel are presented, which show that abrasion patterns and rates differ according to the equipment used, clast size and shape, the clast charge (barrel) and water velocity and bed material (tank). Abrasion is a composite process, and the effects achieved appear to be dominated by percussion in the tank and grinding in the barrel. Breakage, crushing and sandblasting are not modelled effectively, nor are effects achieved on clasts when they form part of the bed. Comparisons are made with other equipment used, the very limited amount of direct field abrasion monitoring, and with the probable suite of processes that may occur under field conditions. Also reviewed are the problems that arise when laboratory weight-loss abrasion coefficients are used or converted into ones of size diminution, as usually derived from field observations of down-channel trends. It is concluded that field abrasion rates generally have been underestimated, as the processes involved are at best only selectively represented by the experimental equipment so far used, and because the results obtained experimentally are capable of misinterpretation when related to field trends. Copyright © 2002 John Wiley & Sons, Ltd. [source] Comparative challenge model of Flavobacterium columnare using abraded and unabraded channel catfish, Ictalurus punctatus (Rafinesque)JOURNAL OF FISH DISEASES, Issue 8 2003J A Bader Abstract The early entry of the fish pathogen Flavobacterium columnare and enhancement by abrasion was studied in channel catfish, Ictalurus punctatus (Rafinesque), using the polymerase chain reaction and a species-specific primer set for a bacterial 16S rRNA gene product. Evaluations were conducted following an abrasion bath immersion challenge with F. columnare. Abrasion, a practice which has historically been used prior to bacterial challenge, had significant effects on the early entry of the pathogen and on cumulative percent survival (CPS). The FvpF1,FvpR1 primer set was useful in detecting the early entry of F. columnare in mucus, skin, gill, blood, liver and trunk kidney tissues in both abraded and unabraded fish following immersion challenge at 29 ± 2 °C. Bacteria were detected earlier in all tissues in abraded fish, except in the trunk kidney. These differences were not significant, except in the case of blood. Mucus, skin and gill tissues were positive for F. columnare earliest regardless of treatment (after 5 min in abraded fish and after 15 min in unabraded fish). CPS following challenge with F. columnare was significantly affected by abrasion, which supports the use of abrasion for the F. columnare challenge model for channel catfish. [source] From Abrasion to Waldos: Connecting the performance support dotsPERFORMANCE IMPROVEMENT, Issue 7 2001Gary J. Dickelman No abstract is available for this article. [source] A Liquid Adhesive Bandage for the Treatment of Minor Cuts and AbrasionsDERMATOLOGIC SURGERY, Issue 3 2002William H. Eaglstein MD Background. Octyl-2-cyanoacrylate is U.S. Food and Drug Administration (FDA) approved for the closure of incisions and lacerations. In animal studies, a more flexible formulation of octyl-2-cyanoacrylate suitable for cuts and abrasions produced faster healing of partial thickness wounds than traditional bandages. Objective. To evaluate the effectiveness of a more flexible octyl-2-cyanoacrylate liquid adhesive bandage for the treatment of minor cuts and abrasions. Methods. One hundred sixty-two volunteers with recent minor cuts or abrasions were recruited and randomized to treatment with either liquid adhesive bandage (LAB) or a control device (Band-Aid brand adhesive bandage, sheer, 2.5 cm). The primary efficacy criterion was complete healing at day 12. Secondary efficacy criteria were the ability of patients to properly apply LAB, and the ability of LAB to stop bleeding, to reduce pain, and to remain on the wound. Results. At day 12 there was no statistical difference between the number of completely healed wounds in the LAB and the bandage-treated patients (P = .493). The ability of patients, as rated by investigators, to effectively apply the LAB device and the bandage was not significantly different (P = .165). Only the LAB provided significant hemostasis (P = .0001) and pain relief (P = .002). conclusion. In this randomized, controlled trial, the LAB was as effective as the control at promoting healing as measured by complete healing at day 12. The LAB was easy to use and gave rapid control of bleeding and pain, forming a film that stayed on wounds well. [source] Healing of hymenal injuries in prepubertal and adolescent girls: a descriptive studyCHILD: CARE, HEALTH AND DEVELOPMENT, Issue 1 2008Richard Reading Healing of hymenal injuries in prepubertal and adolescent girls: a descriptive study . McCannJ., MiyamotoS., BoyleC. & RogersK. ( 2007 ) Pediatrics , 119 , e1094 , e1106 . DOI: 10.1542/peds.2006-0964. Objective, The objective of this study was to identify the healing process and outcome of hymenal injuries in prepubertal and adolescent girls. Methods, This multicentre, retrospective project used photographs to document the healing process and outcome of hymenal trauma that was sustained by 239 prepubertal and pubertal girls whose ages ranged from 4 months to 18 years. Results, The injuries that were sustained by the 113 prepubertal girls consisted of 21 accidental or noninflicted injuries, 73 secondary to abuse, and 19 ,unknown cause' injuries. All 126 pubertal adolescents were sexual assault victims. The hymenal injuries healed at various rates and except for the deeper lacerations left no evidence of the previous trauma. Abrasions and ,mild' submucosal haemorrhages disappeared within 3,4 days, whereas ,marked' haemorrhages persisted for 11,15 days. Only petechiae and blood blisters proved to be ,markers' for determining the approximate age of an injury. Petechiae resolved within 48 h in the prepubertal girls and 72 h in the adolescents. A blood blister was detected at 34 days in an adolescent. As lacerations healed, their observed depth became shallower and their configuration smoothed out. Of the girls who sustained ,superficial', ,intermediate,' or ,deep' lacerations, 15 of 18 prepubertal girls had smooth and continuous appearing hymenal rims, whereas 24 of 41 adolescents' hymens had a normal, ,scalloped' appearance and 30 of 34 had no disruption of continuity on healing. The final ,width' of a hymenal rim was dependent on the initial depth of the laceration. No scar tissue formation was observed in either group of girls. Conclusions, The hymenal injuries healed rapidly and except for the more extensive lacerations left no evidence of a previous injury. There were no significant differences in the healing process and the outcome of the hymenal injuries in the 2 groups of girls. [source] Downstream variation in bed sediment size along the East Carpathian rivers: evidence of the role of sediment sourcesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2008Maria R, doane Abstract Taking as an example six main rivers that drain the western flank of the Eastern Carpathians, a conceptual model has been developed, according to which fluvial bed sediment bimodality can be explained by the overlapping of two grain size distribution curves of different origins. Thus, for Carpathian tributaries of the Siret, coarse gravel joins an unimodal distribution presenting a right skewness with enhanced downstream fining. The source of the coarse material distributions is autohtonous (by abrasion and hydraulic sorting mechanisms). A second distribution with a sandy mode is, in general, skewed to the left. The source of the second distribution is allohtonous (the quantity of sand that reaches the river-bed through the erosion of the hillslope basin terrains). The intersection of the two distributions occurs in the area of the 0·5,8 mm fractions, where, in fact, the right skewness (for gravel) and left skewness (for sand) histogram tails meet. This also explains the lack of particles in the 0·5,8 mm interval. For rivers where fine sediment sources are low, the 0·5,8 mm fractions have a higher proportion than the fractions under 1 mm. For the Siret River itself, bed sediment bimodality is greatly enhanced due to the fact that the second mode is more than 25% of the full sample. As opposed to its tributaries, the source of the first mode, of gravel, is allohtonous to the Siret river, generated by the massive input of coarse sediment through the Carpathian tributaries, while the second mode, of the sands, is local. In this case we can also observe that the two distributions of particles of different origins overlap in the 0·5,8 mm fraction domain, creating the illusion of ,particle lack' in the fluvial bed sediments. Copyright © 2007 John Wiley & Sons, Ltd. [source] Laboratory simulation of clast abrasionEARTH SURFACE PROCESSES AND LANDFORMS, Issue 2 2002J. Lewin Abstract Experimental abrasion of river-bed materials has been widely undertaken, producing ,downstream' fining rates that generally are believed to be much less than those observed in the field. A conclusion commonly adopted has been that sorting processes are more effective than abrasion processes. A comparative evaluation of results from an abrasion tank and a tumbling barrel are presented, which show that abrasion patterns and rates differ according to the equipment used, clast size and shape, the clast charge (barrel) and water velocity and bed material (tank). Abrasion is a composite process, and the effects achieved appear to be dominated by percussion in the tank and grinding in the barrel. Breakage, crushing and sandblasting are not modelled effectively, nor are effects achieved on clasts when they form part of the bed. Comparisons are made with other equipment used, the very limited amount of direct field abrasion monitoring, and with the probable suite of processes that may occur under field conditions. Also reviewed are the problems that arise when laboratory weight-loss abrasion coefficients are used or converted into ones of size diminution, as usually derived from field observations of down-channel trends. It is concluded that field abrasion rates generally have been underestimated, as the processes involved are at best only selectively represented by the experimental equipment so far used, and because the results obtained experimentally are capable of misinterpretation when related to field trends. Copyright © 2002 John Wiley & Sons, Ltd. [source] Crust strength: a wind tunnel study of the effect of impact by saltating particles on cohesive soil surfacesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2001M. A. Rice Abstract A wind tunnel study examined the effect of distributions of saltating particles on sediment surfaces which were characterized by distributions of their tensile strength. The sediments consisted of varying proportions of large sand-sized particles with a fine particle cement. The energies of the impacting particles and the surface strengths were compared with the mass of material lost from the surface. It is important to consider distributions of parameters rather than mean values only, since abrasion and erosion may occur from surfaces not predicted from average strength and saltation velocities. At the impact velocities used in this study (mean velocity 4·4 m s,1, with standard deviation of 0·51), surfaces containing less than 12 per cent fine material were easily eroded, but insignificant erosion occurred when the fine particle content exceeded 60 per cent. Small amounts of cementing material were easily ruptured, allowing the large sand grains to be moved (largely in creep) by the bombarding particles. A significant amount of energy was lost to the bed. As the percentage of fine material increased, the surface became more difficult to break up and less energy was lost to the bed. The probability that erosion will occur for known energy distributions of impacting particles and surface strength can be calculated and the mass loss increases exponentially with a decrease in the percentage of fine cementing particles. Copyright © 2001 John Wiley & Sons, Ltd. [source] The factors influencing the abrasion efficiency of saltating grains on a clay-crusted playaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2001Christopher A. Houser Abstract The entrainment and subsequent transport of PM10 (particulate matter <10,µm) has become an important and challenging focus of research for both scientific and practical applications. Arid and semi-arid environments are important sources for the atmospheric loading of PM10, although the emission of this material is often limited by surface crusts. It has been suggested that the primary mechanisms through which PM10 is released from a crusted surface are abrasion by saltating grains or disturbance by agricultural and recreational activities. To examine the importance of saltation abrasion in the emission of PM10, a series of field wind tunnel tests were conducted on a clay-crusted surface near Desert Wells, Arizona. In a previous part of this study it was found that the emission rate varies linearly with the saltation transport rate, although there can be considerable variation in this relationship. This paper more closely examines the source of the variability in the abrasion efficiency, the amount of PM10 emitted by a given quantity of saltating grains. The abrasion efficiency was found to vary with the susceptibility of the surface to abrasion, the ability of the sand to abrade that surface and the availability of material with a caliper size <10,µm within the crust. Specifically, the results of the study show that the abrasion efficiency is related to the crust strength, the amount of surface disturbance and the velocity of the saltating grains. It is concluded that the spatial and temporal variability of these controls on the abrasion efficiency imposes severe contextual limitations on experimentally derived models, and can make theoretical models too complex and impractical to be of use. Copyright© 2001 John Wiley & Sons, Ltd. [source] Tooth size and skin thickness in mature sockeye salmon: evidence for habitat constraints and variable investment between the sexesECOLOGY OF FRESHWATER FISH, Issue 3 2006S. P. Johnson Abstract ,, Pacific salmon develop many sexually dimorphic features at maturity, and the extent of development varies among populations. In this study, we compared a suite of traits including body length, body depth, jaw length, tooth size and skin mass in male and female sockeye salmon breeding in beach and creek habitats. Both tooth size and skin mass varied positively with body length. Within each of the breeding habitats, males had longer teeth than females, and within each sex, beach spawners had longer teeth than creek spawners. Males also had heavier skin than females in each habitat but, unlike the case with tooth size, creek spawners showed a much stronger relationship between skin mass and body length than did beach spawners. Tooth length was positively related to jaw length and skin mass among individuals within a given sex and habitat. Taken together, these results suggested that variation in tooth size parallels variation in other sexually dimorphic traits. Males and beach spawners tend to exhibit large trait values relative to females and creek spawners, and ,well-endowed' individuals displayed high values of all traits rather than a trade-off as might occur if investment in one trait compromised investment in others. However, the finding that creek fish tended to have thicker skin for a given body length than did beach fish suggested that factors other than merely defense against conspecifics during battle, such as abrasion and desiccation resistance in small streams, may influence the evolution of skin mass in mature sockeye salmon. [source] Tribological Studies of a Zr-Based Glass-Forming Alloy with Different States,ADVANCED ENGINEERING MATERIALS, Issue 11 2009Feng Jiang Abstract The tribological characteristics of a glass-forming alloy, Zr52.5Cu17.9Ni14.6Al10.0Ti5.0, in atomic percent (at.%, Vit 105), with different microstructural states have been investigated. Friction and wear studies were conducted using a ball-on-flat reciprocating sliding apparatus against an AISI E52100 bearing steel under dry condition. The observed wear resistance in an ascending order is: the deformed, creep-tested, and as-cast states. Wear analyses suggested that the wear processes of glass-forming alloys involved abrasion, adhesion, and oxidation. The differences in hardness, free volume, and brittleness in different states significantly affected the friction and wear behaviors of the glass-forming alloys. [source] Different roles of natural and sexual selection on senescence of plumage colour in the barn swallowFUNCTIONAL ECOLOGY, Issue 2 2009Ismael Galván Summary 1Colour may show effects of senescence because the pigment or structures involved in production of colouration deteriorate with age. 2We tested this hypothesis by investigating age-related changes in plumage colour for two feather tracts coloured by eumelanin or pheomelanin in a longitudinal study of a cohort of barn swallows Hirundo rustica that reached very old age (at least 5 years). 3The level of melanization of the throat increased with age in both sexes, but particularly in females. In contrast, the black colour of the plumage of the back was unrelated to age in both sexes. 4These age-dependent patterns of colouration of different feather tracts of male and female barn swallows suggest that effects of senescence are trait-specific depending on their importance in sexual signalling. The red throat colour based on pheomelanin is involved in sexual selection, with a strong effect in males, but not in females. In contrast, the black colour of the back based on eumelanin is unrelated to sexual selection, but is under natural selection due to intense abrasion of this feather tract. 5These findings suggest that the relative importance of natural and sexual selection are important determinants of the pattern and rate of senescence of colour. [source] Eolian processes, ground cover, and the archaeology of coastal dunes: A taphonomic case study from San Miguel Island, California, U.S.A.GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 8 2002Torben C. Rick Geomorphological evidence and historical wind records indicate that eolian processes have heavily influenced San Miguel Island environments for much of the Late Quaternary. The island is almost constantly bombarded by prevailing northwesterly winds, with peak velocities exceeding 75 km/h and wind gusts reaching over 100 km/h. These strong winds played an important role in the location, formation, and preservation of the island's more than 600 archaeological sites. Excavation and surface collection at a stratified Middle and Late Holocene archaeological site on the island's north coast suggest that wind related disturbances result in significant displacement of light fish bones, produce concentrations of shellfish and heavy mammal bones, and cause significant abrasion, etching, and polishing of bones, shells, and artifacts. These data illustrate that wind not only alters surface materials but can significantly disturb subsurface deposits to a depth of at least 20 cm. Working in concert with a variety of taphonomic processes, wind can play a fundamental role in the preservation of archaeological sites and careful scrutiny during excavation and laboratory analysis is required to delineate its effects. © 2002 Wiley Periodicals, Inc. [source] Sediment Distribution Around Glacially Abraded Bedrock Landforms (Whalebacks) at Lago Tranquilo, ChileGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 3 2005Neil F. Glasser Whalebacks are convex landforms created by the smoothing of bedrock by glacial processes. Their formation is attributed to glacial abrasion either by bodies of subglacial sediment sliding over bedrock or by individual clasts contained within ice. This paper reports field measurements of sediment depth around two whaleback landforms in order to investigate the relationship between glacigenic deposits and whaleback formation. The study site, at Lago Tranquilo in Chilean Patagonia, is situated within the Last Glacial Maximum (LGM) ice limits. The two whalebacks are separated by intervening depressions in which sediment depths are generally 0.2 to 0.3 m. Two facies occur on and around the whalebacks. These facies are: (1) angular gravel found only on the surface of the whalebacks, interpreted as bedrock fracturing in response to unloading of the rock following pressure release after ice recession, and (2) sandy boulder-gravel in the sediment-filled depressions between the two whalebacks, interpreted as an ice-marginal deposit, with a mixture of sediment types including basal glacial and glaciofluvial sediment. Since the whalebacks have heavily abraded and striated surfaces but are surrounded by only a patchy and discontinuous layer of sediment, the implication is that surface abrasion of the whalebacks was achieved primarily by clasts entrained in basal ice, not by subglacial till sliding. [source] Wear Mechanisms of TiB2 and TiB2,TiSi2 at Fretting Contacts with Steel and WC,6 wt% CoINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2010Golla Brahma Raju Unlubricated fretting wear tests on TiB2 and TiB2,5 wt% TiSi2 ceramics against two different mating materials (bearing grade steel and WC,6 wt% Co balls) were performed with a view to understand the counterbody-dependent difference in friction and wear properties. The fretting experiments were conducted systematically by varying load (2,10 N) at an oscillating frequency of 4 Hz and 100 ,m linear stroke, for a duration of 100,000 cycles. Adhesion, abrasion, and three-body wear have been observed as mechanisms of material damage for both the TiB2/steel and TiB2/WC,Co tribosystems. The third body is predominantly characterized as tribochemical layer for TiB2/steel and loose wear debris particles for TiB2/WC,Co tribocouple. An explanation on differences in tribological properties has been provided in reference to the counterbody material as well as microstructure and mechanical properties of flat materials. [source] Influence of Wet Mechanical Mixing on Microstructure and Vickers Hardness of Nanocrystalline Ceramic,Metal CompositesINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 5 2008Tatsuo Kumagai Nanocrystalline (nc) ceramic,metal composite bulk samples have been fabricated by consolidation of mixture of attrition-milled (AM) amorphous base ceramic ((ZrO2,3 mol% Y2O3),20 mol% Al2O3) and AM amorphous base metallic (Ti,48 mol% Al) powders using a pulse-current pressure sintering system. Microstructural observations revealed that the ceramic and metallic colonies appear blocky in morphology in the composite bulk samples, and both the ceramic and the metallic colonies consist of a large number of equiaxed fine grains with the sizes of 78,82 and 81,86 nm, respectively. Mechanical mixing treatments by wet ball milling in ethanol before consolidation process are effective for refinement of the ceramic and metallic colonies. In all the obtained composite bulk samples, the ceramic colonies consist of the dominant phase of tetragonal (t) ZrO2 solid solution (ss) together with the minor phases of monoclinic (m) ZrO2ss and ,-Al2O3. On the other hand, the dominant phase in the metallic colonies changes from Ti3Al (,2) to Tiss (,) with an increase in the t -ZrO2ss volume fraction by abrasion of 3 mol% yttria-stabilized tetragonal polycrystalline zirconia balls during wet mechanical mixing treatments. Such a phase transformation from ,2 to , is considered to be due to the decrease in the aluminum content in the metallic colonies by combination of aluminum with oxygen (i.e., the formation of ,-Al2O3), which is probably taken from ethanol (C2H5OH) into the powders during wet mechanical mixing treatments. The obtained nc composite bulk samples show good Vickers hardness values, which are considerably higher than those estimated from the rule of mixture. [source] Development of a minimally invasive epidermal abrasion device for clinical skin sampling and its applications in molecular biologyINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2009J.-M. Lee Synopsis A new abrasion tool (US patent US7087063 B2) has been developed for collecting skin epidermal samples. This device includes a central shaft that holds the probe in a split chuck. Of the variety of probe designs tested, the laser-cut hollow tube (HT) probe abraded the basal layer of the epidermis most consistently, resulting in representative epidermal skin samples. Compared with traditional clinical methods, the abrasion method allows for high-throughput epidermal skin collection with minimal invasiveness to the volunteer subjects. A large number of abrasion samples have been collected in various clinical studies with no adverse effects observed. Epidermal abrasion, when used appropriately and with the optimized probes, can yield high quality tissue samples that are representative of the epidermis. A sufficient quantity of RNA and protein can be obtained for many subsequent molecular and biochemical applications. Because of its minimal invasiveness and high-throughput nature, the abrasion method can be a valuable tool used to investigate the efficacy of topical applications of skin care products. Resume Un nouvel outil d'abrasion (US Patent US 7 087 063 B2) a été développé pour collecter des échantillons de peaux épidermiques. Cet instrument est constitué d'une tige centrale qui tient la sonde dans un mandrin fendu. Parmi tous les modèles de sondes testées, celle constituée d'un tube creux (HT) coupé au laser, abrase la couche basale de l'épiderme le plus régulièrement, conduisant ainsi à des échantillons de peaux épidermiques représentatifs. Comparée aux méthodes classiques, la méthode d'abrasion permet un prélèvement de peaux épidermiques haut débit avec un minimum d'invasion des sujets volontaires. Un grand nombre d'échantillons a été collecté dans diverses études cliniques sans qu'aucun effet adverse n'ait été observé. L'abrasion épidermique, quand elle est utilisée de façon appropriée et avec une sonde appropriée, peut conduire à des échantillons de haute qualité qui sont représentatifs de l'épiderme. Une quantité suffisante d'ARN et de protéines peut être obtenue en vue de tests moléculaires et biochimiques. Du fait de sa faible agressivité et de sa nature haut débit, la méthode d'abrasion peut être un outil précieux utilisé pour étudier l'efficacité des applications topiques de produits de soins cutanés. [source] Hair breakage during combing.INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 6 2007Hair breakage during combing was evaluated by combing tresses and examining photographs of snags of hair fibers in combs. The resultant hair fiber arrangements suggest that breakage likely involves hair-on-hair interactions, and broken fragment size suggests that breakage occurs primarily at or near the hair-comb interface. Compression forces during combing were also measured, and impact loading of a hair fiber over another hair vs. a hair fiber over a comb tooth shows that compression and abrasion are important to breakage during combing and that impact loading of one hair fiber over another during snagging is a probable and important pathway for hair breakage. [source] Occlusal grooves in anterior dentition among Kovuklukaya inhabitants (Sinop, northern Anatolia, 10th century AD)INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 2 2008Y. S. Erdal Abstract Mesiodistally directed grooves have been observed on the occlusal surfaces of nine incisors of five females in a small skeletal population from Kovuklukaya (Sinop, northern Anatolia, 10th century AD). There is no archaeological evidence to explain the cultural practices that must have caused such unusual abrasions of the anterior dentition. Investigations of the geographical characteristics of the region and data gathered on the traditional lifestyles of Çulhal, inhabitants enables us to reach meaningful conclusions about the Kovuklukaya people. According to the direction of the grooves, ecological characteristics of the region, and ethnographic data, it is proposed that the unusual abrasion observed in the Kovuklukaya population may be linked to passing yarn between the anterior teeth to wet it. The grooves in the Kovuklukaya population were found only in female skeletons, indicating the existence of a sex-based division of labour in yarn production. Copyright © 2007 John Wiley & Sons, Ltd. [source] Recording dental caries in archaeological human remainsINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 4 2001Simon Hillson Abstract Dental caries is an important condition to record in archaeological collections, but the way in which recording is carried out has a large effect on the way in which the results can be interpreted. In living populations, dental caries is a disease that shows a strong relationship with age. Both the nature of carious lesions and their frequency change with successive age groups from childhood to elderly adulthood. There is also a progression in the particular teeth in the dentition which are most commonly affected and, in general, the molars and premolars are involved much more frequently than the canines and incisors. Lower teeth are usually affected more than upper, although the condition usually involves the right and left sides fairly equally. In the high tooth wear rate populations represented by many archaeological and museum collections, there is a complex relationship between the form of lesions and the state of wear, which adds yet another range of factors to the changing pattern of caries with increasing age. In the same populations, chipping, fracture and anomalous abrasion of teeth are also common, and these contribute similarly to the distribution and forms of carious lesion observed. Amongst the living, the pattern of ante-mortem tooth loss is important in understanding caries and, in archaeological material, there is also the complicating factor of post-mortem tooth loss. Finally, there is the question of diagnosis. There are diagnostic problems even in epidemiological studies of living patients and, for archaeological specimens, diagenetic change and the variable preservation of different parts of the dentition add further complications. For all these reasons, it is difficult to define any one general index of dental caries to represent the complete dentition of each individual, which would be universally suitable for studying a full range of collections from archaeological sites or museums. Variation in the nature of collections, their preservation, tooth wear, and ante-mortem and post-mortem tooth loss mean that when such a general index appears to differ between sites, there could be many other reasons for this, in addition to any genuine differences in caries incidence and pattern that might have been present. It is suggested here that the best approach is instead to make comparisons separately for each tooth type, age group, sex, lesion type and potential lesion site on the tooth. Copyright © 2001 John Wiley & Sons, Ltd. [source] Patterns of dental wear in the early Maori dentitionINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 3 2001J.A. Kieser Abstract The levels of tooth wear were surveyed in 50 pre-contact Maori skulls (23 of them female) from New Zealand. In addition to a generalized tooth wear index, we evaluated occlusal wear for erosion and abrasion. Occlusal microwear was also investigated using scanning electron microscopy (SEM) images and, finally, the occlusal slope was determined at the level of the first molar teeth. The general pattern of wear was one of severe occlusal reduction with no significant differences between males and females. Both silicone impressions and SEM views confirmed a large component (30%) of erosion. While most individuals had flat wear planes, 33% of males and 44% of females showed reversed Monson's curves. Accentuated Monson's curves were found in 23.8% of males. While these results confirm early studies of the excessive wear experienced by pre-contact Maori, our study shows for the first time that erosion played a significant role in the dental wear of these people. Copyright © 2001 John Wiley & Sons, Ltd. [source] Flow Velocity Effect on Leaf Litter Breakdown in Tufa Depositing System (Plitvice Lakes, Croatia)INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 4 2009Anita Belan Abstract Considerable amount of riparian leaf litter is annually supplied to the cascade Plitvice Lakes and trapped on tufa barriers where it decays together with aquatic macrophytes. These barriers are the sites of heavy calcite precipitation that can widely differ in terms of current velocity. We conducted a leafbag experiment at sites differing in flow velocity and tufa deposition rate. Decomposition of Petasites spp. and Fagus sylvatica was higher under high current (0.80 m/s) and high tufa deposition areas than in low current (< 0.20 m/s) and low tufa deposition areas (k = 0.085 vs. 0.021 for Petasites spp. and 0.009 vs. 0.002 for Fagus sylvatica). We concluded that although tufa deposition could interfere with decomposition by obstructing physical abrasion and also restricting microbial conditioning, thin calcite crusts developed on the surface of the leaves made them more fragile and thus accelerated their decomposition. High current velocity probably magnified this effect by supporting higher tufa deposition and coarser type of tufa fabrics. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Duration of primary moult affects primary quality in Grey Plovers Pluvialis squatarolaJOURNAL OF AVIAN BIOLOGY, Issue 4 2001Lorenzo Serra Feather wear is the natural degradation and breakage of feather structure during the interval between moults. Different rates of feather wear have been observed for primaries of free-living populations of several species of passerines and waders, and this variability has been linked to different concentrations of melanins. In this study primary moult duration explained 59% of the variation in annual rates of primary abrasion (percentage wing length loss) of seven Grey Plover wintering populations, while migration distance explained 14%. The analysis suggests that primary moult duration plays a key role in determining primary durability and hence primary quality. Long distance migrants might evolve more durable primaries, despite the higher predation risks and energetic costs of a prolonged moult. Partial or complete pre-breeding primary moults of first-year waders and complete biannual moults of some passerines might have evolved under selective forces favouring migration with unabraded primaries. [source] Adhesion of a self-etching system to dental substrate prepared by Er:YAG laser or air abrasionJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2008Wanessa C. Souza-Zaroni Abstract The purpose of this study was to assess the microtensile bond strength of a self-etching adhesive system to enamel and dentin prepared by Er:YAG laser irradiation or air abrasion, as well as to evaluate the adhesive interfaces by scanning electron microscopy (SEM). For microtensile bond strength test, 80 third molars were randomly assigned to five groups: Group I, carbide bur, control (CB); II, air abrasion with standard tip (ST); III, air abrasion with supersonic tip (SP); IV, Er:YAG laser 250 mJ/4 Hz (L250); V, Er:YAG laser 300 mJ/4 Hz (L300). Each group was divided into two subgroups (n = 8) (enamel, E and dentin, D). E and D surfaces were treated with the self-etching system Adper Prompt L-Pop and composite buildups were done with Filtek Z-250. Sticks with a cross-sectional area of 0.8 mm2 (±0.2 mm2) were obtained and the bond strength tests were performed. Data were submitted to ANOVA and Tukey's test. For morphological analysis, disks of 30 third molars were restored, sectioned and prepared for SEM. Dentin presented the highest values of adhesion, differing from enamel. Laser and air-abrasion preparations were similar to enamel. Dentin air-abrasion with standard tip group showed higher bond strength results than Er:YAG-laser groups, however, air-abrasion and Er:YAG laser groups were similar to control group. SEM micrographs revealed that, for both enamel and dentin, the air-abrasion and laser preparations presented irregular adhesive interfaces, different from the ones prepared by rotary instrument. It was concluded that cavity preparations accomplished by both Er:YAG laser energies and air abrasion tips did not positively influence the adhesion to enamel and dentin. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Surface damage analysis of retrieved highly crosslinked polyethylene tibial components after short-term implantation,JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008B. M. Willie Abstract The use of highly crosslinked polyethylene (PE) in the knee remains controversial, because of reduced fatigue fracture properties of the material. The current study investigated postmelt surface damage as well as potential contributors to this damage in retrieved highly crosslinked PE tibial components, after short-term in vivo durations. Retrieved conventional PE tibial components were examined for comparison, as well as unused time zero highly crosslinked and conventional PE tibial components for inherent manufacturing surface characterization. Predominant surface damage modes on highly crosslinked PE components were machine mark loss and abrasion, while conventional PE components primarily had machine mark loss, abrasion, and delamination. In vivo duration, PE thickness, and conformity of the design were significant predictors of surface damage on retrieved conventional PE components. Donor weight and the conformity of the design were significant predictors of surface damage on retrieved highly crosslinked PE components. This retrieval data on highly crosslinked PE tibial components suggest that in vivo wear occurred, observed as postmelt surface damage. The highly crosslinked Durasul material examined in this retrieval study appeared to outperform the conventional PE components made from 4150 resin, ram-extruded and ,-sterilized in air, but not the conventional components made from 1020 resin, compression molding and , sterilization in nitrogen. Early retrieval data of highly crosslinked PE tibial components are important to serve as a benchmark to be compared with future longer-term retrieval studies investigating whether surface damage translates to clinically relevant particulate wear debris generation and PE clinical performance. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Modeling UHMWPE wear debris generationJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2007H. Baudriller Abstract It is widely recognized that polyethylene wear debris is one of the main causes of long-term prosthesis loosening. The noxious bioreactivity associated with this debris is determined by its size, shape, and quantity. The aim of this study was to develop a numerical tool that can be used to investigate the primary polyethylene wear mechanisms involved. This model illustrates the formation of varying flow of polyethylene debris with various shapes and sizes caused by elementary mechanical processes. Instead of using the classical continuum mechanics formulation for this purpose, we used a divided materials approach to simulate debris production and release. This approach involves complex nonlinear bulk behaviors, frictional adhesive contact, and characterizes material damage as a loss of adhesion. All the associated models were validated with various benchmark tests. The examples given show the ability of the numerical model to generate debris of various shapes and sizes such as those observed in implant retrieval studies. Most of wear mechanisms such as abrasion, adhesion, and the shearing off of micro-asperities can be described using this approach. Furthermore, it could be applied to study the effects of friction couples, macroscopic geometries, and material processing (e.g. irradiation) on wear. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] Manufacturing, mechanical characterization, and in vitro performance of bioactive glass 13,93 fibersJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2006E. Pirhonen Abstract Fibers were manufactured from the bioactive glass 13,93 by melt spinning. The fibers were further characterized by measuring their tensile and flexural strength, and their in vitro performance was characterized by immersing them in simulated body fluid, which analyzed changes in their mass, their flexural strength, and surface reactions. The strength of glass fibers is highly dependent on fiber diameter, test method, and possible surface flaws, for example, cracks due to abrasion. In this study, the thinnest fibers (diameter between 24 and 33 ,m) possessed the highest average tensile strength of 861 MPa. The flexural strength was initially 1353.5 MPa and it remained at that level for 2 weeks. The Weibull modulus for both tensile and flexural strength values was initially about 2.1. The flexural strength started to decrease and was only ,20% of the initial strength after 5 weeks. During the weeks 5,40, only a slight decrease was detected. The flexural modulus decreased steadily from 68 to 40 GPa during this period. The weight of the samples initially decreased due to leaching of ions and further started to increase due to precipitation of calcium phosphate on the fiber surfaces. The mass change of the bioactive glass fibers was dependent on the surface area rather than initial weight of the sample. The compositional analysis of the fiber surface after 24 h and 5 weeks immersion did confirm the initial leaching of ions and later the precipitation of a calcium phosphate layer on the bioactive glass 13,93 fiber surface in vitro. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Influence of storage regime prior to abrasion on surface topography of restorative materialsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2003Cecilia Pedroso Turssi Abstract This investigation was carried out to evaluate the effect of storage conditions prior to brushing simulation on surface texture of restorative materials. One resin-modified glass ionomer (Fuji II LC Improved/GC Corp.), one polyacid-modified composite resin (Dyract AP/Denstply), one microfill composite (Durafill VS/Kulzer), and one hybrid (Filtek,Z250/3M) composite were tested. Forty-five standardized cylindrical specimens of each material were made and randomly divided into three groups according to their subsequent storage conditions: distilled deionized water, artificial saliva, or pH-cycling regime. After 24 h, the experimental units were finished and polished and the surface roughness was measured to obtain Ra baseline values (Bv). Samples were subjected to their assigned storage regime and brushed afterwards. By the end of 10 repetitions of this protocol, final surface roughness readings (Fv) were taken. The analysis of covariance (, = 0.05), considering the covariate Bv showed a significant interaction between restorative material and storage condition (pvalue = 0.0002). Tukey's test revealed that the pH-cycling model provided a significantly lower surface roughness for Fuji II LC and Dyract AP than did the other media. For both composites no significant difference among storage regimes was detected. Under a condition simulating dynamic variation in pH prior to abrasion, the resultant surface texture may be either smoothed down or unchanged, depending on the restorative material, when compared to the effect provided by artificial saliva and distilled deionized water. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 65B: 227,232, 2003 [source] Management of night-time urinary incontinence in residential settings for older people: an investigation into the effects of different pad changing regimes on skin healthJOURNAL OF CLINICAL NURSING, Issue 3 2003Mandy Fader BSc Summary ,,Absorbent pads are the main method of managing urinary incontinence in residential settings for older people. ,,Improvements in technology have resulted in highly absorbent products which may be worn all night, but the effects of prolonged pad wearing on aged skin are unknown. ,,The aim of this study was to examine the effects of two different pad changing regimes on skin health. ,,A cross-over design was used. ,,Subjects from residential settings were randomly allocated to one of two pad changing regimes: a frequent pad changing regime or a less frequent pad changing regime. Each regime lasted 4 weeks and was followed by the alternative regime. ,,Skin measurements were taken twice during each regime using (i) the Diastron Erythema meter, (ii) a visual grading scale, (iii) the Servomed evaporimeter, and (iv) a pH meter. The primary outcome variable was the Diastron Erythema meter index. ,,Eighty-one subjects completed the study. ,,No significant differences were found in the severity of erythema, or skin pH, between regimes. Measurements of trans-epidermal water loss were significantly higher in the less frequent pad changing regime indicating that skin was ,wetter' (P = 0.01; 95% CI: 2.89,21.39). ,,Five subjects developed grade 2 pressure ulcers (abrasions) during the less frequent pad changing regime, but none in the frequent pad changing regime; this result was not significant (P = 0.1; 95% CI: 0,1.09). ,,No evidence was found that a less frequent pad changing regime has an effect on skin erythema or pH. ,,There is evidence that skin is wetter which may make it more vulnerable to friction and abrasion. ,,The statistically non-significant finding of greater incidence of grade 2 pressure ulcers is a cause for concern and merits further investigation because of the clinical significance of loss of skin integrity. [source] | |||||||||||||||||||||||||||||||||||||||||||