EXTRACTION OF RAILROAD OBJECTS FROM VERY HIGH RESOLUTION HELICOPTER-BORNE LIDAR AND ORTHO-IMAGE DATA

LiDAR (Light Detection and Ranging) sensors and digital aerial camera systems using a slow and low flying aircraft provide a new quality of data for a variety of promising large-scale applications. The main of this study objective is the development of methods for the automated object extraction of railway infrastructure from combined helicopter-based extremely dense laser scanner measurement points and very high resolution digital ortho-imagery. Thus, different existing methods from digital image processing, image segmentation and object recognition have been compared regarding their performance, output quality and level of automation. It turned out that all existing methods are not suitable to meet the requirements (geometrical accuracy of the result, amount of data to be processed etc.). Since original LiDAR point data provides a higher accuracy than derived DTM raster data or ortho-imagery new suited methods for the object extraction from point clouds have been developed. For the extraction of linear features, such as rails and catenaries, two new methods were implemented. The first method sets up on pre-classified laser points as input data. Therefore the RANSAC algorithm was implemented successfully to extract linear objects within the environment of MATLAB and ArcGIS. Second, a knowledge-based classification method was designed to compare a reference profile with the situation along the track using IDL. The results show new prospects to automatically extract railroad objects with a high geometrical accuracy from extremely dense LiDAR data without using aerial imagery. The decision not to use image data was especially caused by the enormous data amount t

Masticatory muscles show differential expression of MHC-isoforms in mdx-mice

Background: Duchenne Muscular Dystrophy (DMD) and its murine model, mdx, are characterized by Ca2+ induced muscle damage, fibrosis and muscle weakness. Furthermore, DMD patients have distorted dentofacial morphology which could be a result of changed masticatory mechanics due to muscular dysfunction. Aim: To determine potential changes in masticatory mechanics we searched for morphological abnormalities including nuclei localisation, fibre diameters and collagen expression and examined the expression of myosin heavy chain (MHC)-isoforms in control and mdx mice. Methods: The mRNA and protein levels of the MHC-isoforms were studied using quantitative RT-PCR, western blot analyses and histochemistry in Musculus masseter, temporalis, soleus and tongue of both mouse strains. Results: Dystrophin-deficient masticatory muscles contained 11-75% fibres with centralized nuclei, numerous inflammatory foci and an accumulation of collagen except tongue. Furthermore, a significant increased mean fibre diameter was observed all tested mdx muscles. In contrast to soleus muscle the MHC type I isoform was not detectable in masticatory muscle tissues of control and mdx mice. In mdx masticatory muscles and tongue MHC type IIb and IIx were significantly down regulated. Conclusion: These observations suggest that mdx masticatory muscles are differentially affected by the disease process. However, the observed down regulation of the MHC IIx and IIb isoforms may be responsible for the functional misbalance of masticatory muscles in DMD and could be causing morphological changes which are observed in this disorder

Frictional properties of aesthetic brackets

The purpose of this study was to compare the frictional properties of two self-ligating aesthetic brackets, Opal (Ultradent Products) and Oyster (Gestenco Int.), with those of four conventionally ligated aesthetic brackets, Transcend (3M Unitek), Inspire (Ormco), Allure (GAC Int.), and Image (Gestenco Int.). Friction was tested with different wire dimensions and qualities [stainless steel (SS) wire 0.017 x 0.025 inches; SS 0.019 x 0.025 inches; TMA 0.019 x 0.025 inches] using a Zwick testing machine. All brackets had a 0.022-inch slot and the prescription of an upper first premolar of the Roth system (tip: 0 degrees, torque: -7 degree). Each bracket/archwire combination was tested 10 times and each test was performed with a new bracket/wire sample that was pulled through twice. Additionally, two sets of 30 Opal brackets each were aged with an ageing machine under standardized conditions for 9-10 and 18-20 months, respectively. Friction of the aged brackets was tested with identical wire dimensions and qualities using the same testing procedure. All data were statistically analysed with unsigned comparisons of all bracket/ wire combinations using GLM and the Games-Howell post hoc test. The results showed Opal brackets to have the lowest frictional forces for all wire dimensions and qualities. Furthermore, friction was lower at a significant level (P <= 0.05) compared with all other brackets. Only the Oyster bracket had similar values in combination with a 0.019 x 0.025 inch SS wire. Aged Opal brackets showed higher values than new ones, but still lower frictional forces than the four conventional aesthetic brackets. Friction was comparable with the new Oyster bracket

Conventionally ligated versus self-ligating metal brackets--a comparative study

The purpose of this study was to compare the frictional properties of four self-ligating metal brackets, Speed, Damon 2, In-Ovation, and Time, with those of three conventionally ligated metal brackets, Time, Victory Twin, and Discovery. The self-ligating Time bracket can also be used as a conventionally ligated bracket. Friction was tested 20 times for each bracket/wire combination using a Zwick testing machine with stainless steel wires in three different wire dimensions (0.017 x 0.025, 0.018 x 0.025, and 0.019 x 0.025 inches). All brackets had a 0.022 inch slot and the prescription of an upper first premolar. The data were statistically analysed with unsigned comparisons of all bracket/wire combinations using the Mann-Whitney U-test and the Games-Howell post hoc test. The results showed almost all brackets to have the lowest frictional force with a wire dimension of 0.018 x 0.025 inch. Friction of the self-ligating brackets using wire with a dimension of 0.018 x 0.025 inches was 45-48 per cent lower than with 0.017 x 0.025 and 0.019 x 0.025 inch wires. Friction of the conventionally ligated brackets showed a 14 per cent or less reduced friction with 0.018 x 0.025 inch wire compared with 0.017 x 0.025 and 0.019 x 0.025 inch wires. The self-ligating metal brackets showed lower frictional forces with a 0.018 x 0.025 inch wire than conventionally ligated brackets, whereas conventionally ligated brackets showed lower friction with 0.017 x 0.025 and 0.019 x 0.025 inch wire. Friction values vary with different bracket/archwire combinations and, therefore, the choice of a bracket system for treatment should consider the correct wire dimension to produce the lowest possible frictional forces

RT-PCR quantification of mRNA Myosin isoforms in muscle of mdx-mice

Objective: The lack of dystrophin in the mouse mutant mdx leads to muscle degeneration and is the most used animal model for Duchenne muscular dystrophy (DMD). The DMD patients have distorted dentofacial morphology which could be a result of changed masticatory mechanics due to muscular damage and dysfunction. The aim of this study is to investigate the regeneration process in the masticatory muscles of mdx-mouse due to the analysis of mRNA expression of the Myosin heavy chain (MyHC) isoforms. METHODS: In a mouse model (mdx and controls; 100 days old, n=10 each group) we examined myosin heavy chain - isoforms expression mRNA in the masticatory mucles and taking samples from masseter (MAS), temporalis (TEM) and tongue (TON) muscles. RESULTS: In control mice IIx isoforms are more expressed as IIb in MAS (65% vs. 30%, p<0.05) and TEM (83% vs. 12%, p<0.05), in TON that relation being inversed (26% vs. 72%, p<0.05). The fiber type distribution in MAS did not change in mdx, as compared to the controls although slight insignificant increase in IIb was observed. In TEM the content of IIb MyHC isoforms was reduced in comparison to the controls (12% resp. 37%; p < 0.01). The TON muscle in the mdx group represents a strongly reduced expression of IIx (26%; controls 31%, p<0.05) and IIb isoforms (74%; controls 69%, p<0.05). All masticatory muscles appeared to have very small amounts of type IIa and no content of type I. These findings were also confirmed by immunohistochemistry and Western blot analysis. CONCLUSION: The observed down regulation of the expression of IIx and IIb MyHC isoforms is an evidence for muscle adaptation process due to dystrophin absence and may be responsible for functional misbalance of masticatory muscles resulting in morphological changes that are observed in DMD patients.No Full Tex