270 research outputs found
FT22 Proff 5-key tenoroon: measurements, photos, endoscopic video
No full textData set of FT22 Proff 5-key tenoroon containing detailed external and internal measurements, photos, and an endoscopic video.
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Seismic performance of masonry cross vaults: learning from historical developments and experimental testing
No full textConsidering the seismic behaviour of cultural heritage buildings, an influential role is played by masonry vaults, often representing the most vulnerable part of the construction. Despite their long-lasting history and the damage observation following the Italian earthquakes of the recent past, research in this area is still limited. In this regard, the present thesis is devoted to the study of the seismic behaviour of masonry groin vaults, considered as one of the most diffused vault type in European seismic prone areas in cloisters, palaces and churches. Groin vaults are resulting from the intersection at a right angle of two semi-cylindrical shells on a square bay, and can be addressed as the simplest form of cross vaults, defined as a combination (compound) of curved shells whose thrust converges along the diagonals to isolated abutments. The goal of this work is met via an integration of laboratory tests and numerical analyses.
The first part of the thesis reviews the historical developments of the cross vault, the structural methods adopted by the scientific community and the damage evidences after laboratory experiments and post-seismic observation. The subsequent part deals with shaking table tests on a scaled arch built with dry-joint 3D printed voussoirs. The experimental campaign had a twofold purpose. On the one hand it gave insight into the seismic behaviour of masonry arches and, on
the other hand, thanks to the tracking motion system employed to record the tests, it provided valuable information to calibrate a three-dimensional numerical model.
The physical model was studied using a commercially available FEM software, namely DIANA (from TNO Delft), assuming rigid-infinitely resistant blocks and Coulomb friction interfaces. The nonlinear analyses regarded both the static and dynamic behaviour, shading light on the influence of interface stiffness and damping. The numerical model was subsequently extended to the study of the three-dimensional behaviour of groin vaults. In particular, the analyses focused on the results available in literature following a recent experimental campaign on a 1:5 scaled vault. The model was able to properly catch the maximum strength and the failure mechanism recorded in the quasi-static tests. Analogies between the nonlinear behaviour of the vault and the free-standing rigid block undergoing incremental horizontal force are also discussed.
The last part of the thesis is dedicated to a sensitivity analysis aimed at evaluating the influence of the main geometrical and mechanical parameters on the seismic capacity and failure mechanisms of groin vaults. A non-commercial code implemented in Matlab, based on the upper bound approach of standard limit analysis, was used. The results were finally processed through a multiple linear regression analysis in order to get simplified analytical equations for expedite
seismic evaluation of existing groin vaults
The role of hypoxia in orthodontic tooth movement.
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How to Cite this Article
International Journal of Dentistry
Volume 2013 (2013), Article ID 841840, 7 pages
http://dx.doi.org/10.1155/2013/841840
Review Article
The Role of Hypoxia in Orthodontic Tooth Movement
A. Niklas, P. Proff, M. Gosau, and P. Römer
Department of Orthodontics, University Medical Center Regensburg, 93053 Regensburg, Germany
Received 6 June 2013; Accepted 16 September 2013
Academic Editor: Stephen Richmond
Copyright © 2013 A. Niklas et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Orthodontic forces are known to have various effects on the alveolar process, such as cell deformation, inflammation, and circulatory disturbances. Each of these conditions affecting cell differentiation, cell repair, and cell migration, is driven by numerous molecular and inflammatory mediators. As a result, bone remodeling is induced, facilitating orthodontic tooth movement. However, orthodontic forces not only have cellular effects but also induce vascular changes. Orthodontic forces are known to occlude periodontal ligament vessels on the pressure side of the dental root, decreasing the blood perfusion of the tissue. This condition is accompanied by hypoxia, which is known to either affect cell proliferation or induce apoptosis, depending on the oxygen gradient. Because upregulated tissue proliferation rates are often accompanied by angiogenesis, hypoxia may be assumed to fundamentally contribute to bone remodeling processes during orthodontic treatment
Long-term effects of tongue piercing — a case control study
No full textThe aim of this study was to evaluate tooth and periodontal damage in subjects wearing a tongue piercing (TP) in comparison to matched control subjects without tongue piercing. Members of the German Federal Armed Forces who had TP (group TP) and a matched control group (group C) volunteered to take part in the study. The time in situ, localization and material of TP were documented. Dental examinations included DMF-T, oral hygiene, enamel fissures (EF), enamel cracks (EC) and recessions. Statistical analysis was determined by chi (2) test and the t test. Both groups had 46 male subjects (mean age 22.1 years). The piercings had been in situ for 3.8 +/- 3.1 years. Subjects in the TP group had a total of 1,260 teeth. Twenty-nine subjects had 115 teeth (9.1%) with EF (67% lingual). In group C (1,243 teeth), 30 subjects had 60 teeth with EF (4.8%, 78% vestibular) (p < 0.01). Thirty-eight subjects belonging to group TP had EC in 186 teeth (15%). In group C, 26 subjects with 56 teeth (4.5%) were affected by EC (p < 0.001). Twenty-seven subjects in group TP had 97 teeth (7.7%) with recessions. Lingual surfaces of anterior teeth in the lower jaw were affected most frequently (74%). In group C, 8 subjects had 19 teeth (1.5%) with recessions (65% vestibular). Differences between the two groups were statistically significant (p < 0.001). Tongue piercing is correlated with an increased occurrence of enamel fissures, enamel cracks and lingual recessions. Patients need better information on the potential complications associated with tongue piercing
Effects of mechanical and bacterial stressors on cytokine and growth-factor expression in periodontal ligament cells
No full textThe goal of the study was to examine the effects of a mechanical (orthodontic force simulation by static compressive loading) and a bacterial (endotoxins from a heat-inactivated gram-negative periodontal pathogen) stressor on the expression patterns of factors that are key to regulating osteoclastogenesis and bone remodeling. Three experimental groups were formed with fifth-passage periodontal ligament (PDL) fibroblasts treated by the static application of compressive force (2 g/cm(2)), heat-inactivated aggregatibacter actinomycetemcomitans (1 x 10(7) cells), or both of these stressors combined. Real-time polymerase chain reaction (RT-PCR) was used to study gene expression of IL-6, IL-8, COX-2, IGF-1, VEGF, and MMP-13 in the 3 groups. Protein levels of COX-2, prostaglandin E2 (PGE(2)), and IL-8 production were quantified using immunoblotting and enzyme-linked immunosorbent assay (ELISA). The mechanical stressor upregulated the genes of COX-2, IL-8, IGF-1, and MMP-13 in PDL fibroblasts and the bacterial stressor upregulated IL-6, IL-8, COX-2 and MMP-13. Both stressors in combination upregulated VEGF and caused COX-2 gene expression to increase further; the latter effect was also detected at the protein level and indirectly via the enhanced production of PGE(2). We noted that the posttranscriptional regulation of IL-8 was induced by the mechanical stressor and influenced by PGE(2). While mechanical-stressor application increased the gene expression of COX-2, IL-8, and VEGF in the presence of the bacterial stressor, IL-8 production was posttranscriptionally regulated by the mechanical stressor, whereas COX-2 expression correlated with enhanced production of the inflammatory tissue hormone PGE(2), which exerted a suppressive effect on endotoxin-induced IL-8 production
Bilateral in vivo assessment of mandibular chewing dynamics using multi-slice real-time MRI: the rotation-translation-ratio in normal and displaced TMJ discs
No full textDIFFERENT BONE SENSITIVITY TO MALFORMATIONS INDUCED BY PROCARBAZINE IN FETAL RATS
No full textThe study aimed at to induce cleft-lip-alveolus-palate (CLAP) applying procarbazine in rat fetuses at the 14(th) day of pregnancy, to supply thiocyanate and/or folic acid Sufficient for preventive treatment and Subsequently to investigate cleft extent in the palatal area as well as boric Maturity. In this animal model, female primiparous inbred rats (LEW.IA) Were used. The gravid animal were separated into treatment groups: group K (Control), group P (procarbazine), group TP (thiocyanate and procarbazine) and group FTP (folic acid, thiocyanate, procarbazine). The results reveal that procarbazine may induce clefts in the palate area. Clefts Occurred most frequently in group TP and mainly comprised subtotal clefts of the posterior secondary palate. As for palatal length, group FTP displayed the longest palate which was significantly different only from group K. A different picture was shown for the secondary palate with group TP displaying the shortest Values which were significantly different from those in groups K, P, and FTR Thus, group TP showed the most marked negative changes both for cleft frequency arid palatal length as compared to group K and the other groups. The preventive application of either thiocyanate (TP) or thiocaynate and folic acid combined (group FTP) failed to completely prevent cleft formation in the palate area. In conclusion, a preventive effect on palatal clefts arid growth inhibition Could not be proved for the vitaminoid thiocyanate
su un problema di caratterizzazione di certe classi formule risolto tramite la nozione di interpretabilità relativa
No full textIntroduzione ad una classe di problemi di logica della interpretabilità relativa detti "problema di Guaspari" per varie teorie e "survey" dei risultati ottenuti e pubblicati dall'autore in collaborazione con i proff. De Jongh e Montagna intorno ad essi.Introduction to a class of problems of the logic of relative interpretability called "Guaspari problem" for various theories and survey of the results obtained and published by the author in collaboration with the proff. De Jongh and Montagna around them
DIFFERENT BONE SENSITIVITY TO MALFORMATIONS INDUCED BY PROCARBAZINE IN FETAL RATS
No full textThe study aimed at to induce cleft-lip-alveolus-palate (CLAP) applying procarbazine in rat fetuses at the 14(th) day of pregnancy, to supply thiocyanate and/or folic acid Sufficient for preventive treatment and Subsequently to investigate cleft extent in the palatal area as well as boric Maturity. In this animal model, female primiparous inbred rats (LEW.IA) Were used. The gravid animal were separated into treatment groups: group K (Control), group P (procarbazine), group TP (thiocyanate and procarbazine) and group FTP (folic acid, thiocyanate, procarbazine). The results reveal that procarbazine may induce clefts in the palate area. Clefts Occurred most frequently in group TP and mainly comprised subtotal clefts of the posterior secondary palate. As for palatal length, group FTP displayed the longest palate which was significantly different only from group K. A different picture was shown for the secondary palate with group TP displaying the shortest Values which were significantly different from those in groups K, P, and FTR Thus, group TP showed the most marked negative changes both for cleft frequency arid palatal length as compared to group K and the other groups. The preventive application of either thiocyanate (TP) or thiocaynate and folic acid combined (group FTP) failed to completely prevent cleft formation in the palate area. In conclusion, a preventive effect on palatal clefts arid growth inhibition Could not be proved for the vitaminoid thiocyanate
La cura della famiglia e il mondo del lavoro. Un piano di politiche familiari
No full textCuratela di un volume miscellaneo che riporta i risultati di ricerche e convegni svolti per l'Osservatorio Nazionale sulla Famiglia in collaborazione con il Ceposs dell'Università di Bologna (proff. P. Donati e R. Prandini
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