1,720,988 research outputs found
The effect of tissue condition and applied load on Vickers hardness of human trabecular bone
No full textHardness of trabecular human bone, evaluated by microindentation testing, has generally been measured on embedded tissues. It was known that this was not ideal but it had been preferred to other conditions (e.g. wet or dehydrated) as the trabeculae could withstand the applied load and the measurements were reliable. The aim of this study was to investigate if the tissue condition of the specimen and the applied load would alter the hardness values measured by Vickers microindentation. Vickers hardness values of human trabecular bone from the femoral head, prepared in three different ways (wet, dry and embedded) and tested with two different loads (50 and 25 gf), were measured. No significant difference was found between the two different loads. However, in several cases the 50 gf indentations had to be redone because they were too large or the trabecula broke locally. Even if the outlines of the indentations on wet bone were slightly less marked than the ones done on dehydrated or embedded bone, it was possible to measure the hardness. Significant differences of Vickers hardness values were found between the three preparations: the hardness increased passing from wet to dried (10%) and from wet to embedded (35%). Whereas the variation coefficient of the three tissue conditions were comparable. In conclusion, it is recommended to test human trabecular bone in a wet condition as it better represents the in vivo condition. Furthermore the use of a 25 gf load is suggested, allowing hardness measurements on almost all trabeculae without breaking them
HW/SW Codesign of a Multiple Injection Driver Automotive subsystem using a configurable System-on-Chip
No full textPrassi e teoria della lingua in Belli
No full textLa poesia del Belli risponde a un preciso progetto di riflessione sulle modalità della relazione fra lingua letteraria e lingua locale secondo una modalità che prende avvio dalle riflessione dantesche condotte nel "De vulgari eloquentia"
Structural parameters and mechanical strength of cancellous bone in the femoral head in osteoarthritis do not depend on age
No full textFor normal bone, aging has been associated with a decrease of both density and failure strength, and with the development of pathologies such as osteoporosis. Conversely, it has been reported that another common disease, osteoarthritis, may alter these age-related changes in cancellous bone, suggesting that it may have a protective role against osteoporosis and the correspondent fracture risk. It was reported that in the principal compressive region of the femoral head in osteoarthritis the bone density does not depend on age. However, it is not clear if this independence on age of the cancellous bone density corresponds also to a reduced dependence on age of the strength to failure. The present work examined cancellous bone from the principal compressive region of the femoral head of 37 patients having severe osteoarthritis. The aim was (1) to investigate the dependence on age of both the structural parameters and the ultimate stress and (2) to investigate the relationships between the ultimate stress and the structural parameters. Using X-ray microcomputed tomography, three-dimensional structural parameters, such as bone volume fraction, direct trabecular thickness and structure model index were calculated. Then the specimens were compressed to failure to determine the ultimate stress. It was found that none of the investigated structural parameters did depend on age, and also the ultimate stress did not depend on age (p>0.05 for all regressions on age). In addition, the ultimate stress was significantly correlated with the structural parameters, primary with the minimum bone volume fraction and the average bone volume fraction (R(2)=0.95 and R(2)=0.84, respectively). These findings show that severe osteoarthritis or a related factor may change the age dependences of both the structural parameters and the mechanical properties usually reported for normal cancellous bone. These results suggest for this pathology to have a protective role against the age-related decrease in density, the age-related deterioration of the microarchitecture and the age-related decrease of the failure strength for the cancellous bone in the principal compressive region of the human femoral head
Transaction Level Modeling and Performance Analysis in SystemC of IEEE 802.15.4 Wireless Standard
Full text linkGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dependence of mechanical compressive strength on local variations in microarchitecture in cancellous bone of proximal human femur
No full textHuman cancellous bone is a heterogeneous material. Despite this, most of the published studies report correlations between mechanical properties and morphometric parameters averaged on the whole specimen. This work investigated whether local variations in morphometric parameters were linked to the localized failure regions of cancellous bone. Additionally, it was examined whether local values of morphometric parameters can predict the ultimate stress better than the average bone volume fraction (BV/TV). Cylindrical cancellous bone specimens extracted along the primary compressive group of human femoral heads were studied. These were microCT-imaged to assess the morphometric parameters, compressed to determine the ultimate stress, and rescanned by microCT to visualize the failure region. Failure involved slightly less than half of the free height of the specimens. Significant differences were found in the morphometric parameters calculated in the failure and in the non-failure regions. The cross-sections containing minimum BV/TV values were those most often located inside the failure region (83%, p<0.001). Regression analysis confirmed that variations in BV/TV best describe variations in ultimate stress (R2=0.84) out of the averaged morphometric parameters. The prediction of ultimate stress increased when minimum or maximum values of the morphometric parameters were taken, with the highest prediction found by considering the minimum BV/TV (R2=0.95). In conclusion, due to the heterogeneity of cancellous bone, there may exist regions characterized by a different microarchitecture, where the bone is weaker and consequently is more likely to fail. These regions mostly contain minimum values in BV/TV, which were found to predict ultimate stress better than average BV/TV
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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