No description available.

No description available.

No description available.

Osteoarthritis is the most common type of arthritis, and is characterized by the loss of articular cartilage in a joint. This eventually leads to painful bone on bone interactions. Since the loss of cartilage is permanent, the main treatment for this disease is pain management until a full joint replacement is needed. To test new potential treatments a consistent way to measure cartilage thickness is needed. The current standard used in the knee to represent cartilage uses joint space width measured from x-rays. This measurement is highly variable, and does not directly show cartilage. Unlike x-rays, magnetic resonance imaging (MRI) can provide direct visualization of soft tissues in the body, like cartilage. One specific MRI method called balanced steady-state free precession (bSSFP) provides useful contrast between cartilage and its surrounding tissues. This allows easy delineation of the cartilage for volume and thickness measurements. Using bSSFP has unique challenges, but can provide quantitative MR tissue parameter information in addition to volume and thickness measurements.Although bSSFP provides useful contrast, it is highly sensitive to variations in the main magnetic field. This results in dark bands of signal null across an image referred to as banding artifacts. There are a few new methods for mitigating this artifact. An analysis of banding artifact reduction methods is presented in this dissertation. The new methods are shown to be better than traditional methods at reducing banding artifact. However, they do not provide as of high signal to noise ratio as traditional methods in most cases. This analysis is helpful in obtaining artifact free images for volume and thickness measurements.Image distortion can be created when there is a magnetic susceptibility mismatch between bordering substances being imaged, like in the sinuses where air and body tissues meet. A map of the main magnetic field variation can be used to fix this distortion in post processing. A novel method for obtaining a map of the main magnetic field variation is developed using bSSFP in this dissertation. In cases where bSSFP contrast is desirable this map can be obtained with no additional scan time.A new way to sift out MR tissue parameters: T2, T1, and M0 is presented in this dissertation using bSSFP. This method obtains biomarkers that can potentially show the presence of Osteoarthritis before cartilage degeneration begins at the same time as anatomical images. Adjunct scans do not need to be run to get these extra parameters saving scan time. Unlike many adjunct scans, it is also resolution matched to the anatomical images.

The submitted work compares results of two forest inventories conducted on the plot of 200 ha within the forestry concession in the tropical rainforest in the Peruvian Amazon. First inventory conducted in 2007 used for field data collection the common method with tapes and mechanical compasses. The second inventory conducted in 2008 used a set of electronic devices, consisting of a field computer, laser rangefinder, electronic compass, a GPS unit and a specialized software Field-Map. In both inventories the positions of all trees with a dbh bigger or equal 400 mm were mapped and following attributes were recorded: position, species, total height, trunk height and dbh. Significant differences were discovered between both methods and the inadequacies were described. The results from the comparison study show that the method conducted using electronic devices is faster and more exact in measurement of tree attributes and in navigation on the plot. However, nor use of this method encompassed to map all the trees and that is why the distance sampling method for population density estimation was used for completion of inventory results. The population map of big trees was created and used for inventory simulations using circular and belt plots of different size and different density with the aim to find most suitable variants. Results of simulated inventories were evaluated regarding their accuracy and time expenses and the variants suitable for use in the zone were suggested.

The thesis examines the amount of growth and production characteristics of the set of stands, in which the transformation to the selective management method was started about fifty years ago. These are the parts of Klepacov and Pokojná hora, which are part of Habrůvka and the forest management complex ŠLP ML Křtiny. Repeated statistical inventory analysis using Field-map technology identified the necessary dendrometric variables. Some of them served to calculate the total current increment. Using the MS Excel program and the solver function, the coefficients of elevation functions for individual trees in the given sections were calculated. As a result of this step, the missing height, stock, enumeration of the basal area, the number of trees per hectare, etc. were calculated according to the model. On the basis of these data, individual production and growth characteristics were determined and then compared. These quantities were compared mainly at the level of inventory areas. Typology has also been omitted. Finally, the appropriate size of the optimal basal area was determined, taking into account the maximum value of the volume increment. In this case, a more detailed level in the form of individual trees was used outside the level of the inventory area, for the more precise determination of the values of the enumerating basal area. The basal area was evaluated in five variants according to the forest type (spruce, mixed, beech) and forest types (3S – fresh oak beech and 4S - fresh beech). From the individual tree level, the set value of the basal area was then recalculated to the target tree thickness in centimeters for possible practical use in selecting trees.