ABSTRACT
Gullies are a major threat to ecosystems, potentially leading to land degradation, groundwater depletion, crop loss, debris flow, and desertification. Gullies are also characterized by having a fast development and turning into primary sediment sources. Despite their impact, we have but scarce understanding of how gully erosion evolves and how to model it. In this paper, we propose a new gully erosion model that is based on the classical premise of net shear stress, i.e., hydraulic shear stress minus critical (resistant) shear stress, to calculate detachment rates. In order to calculate hydraulic shear stress, we developed a new equation derived from the principle of minimum cross-entropy; it was validated with laboratory measures from the literature with a Nash-Sutcliffe Efficiency of 0.95. Soil samples were analysed in the laboratory to assess critical shear stress and other soil properties. The novel gully erosion model was implemented in three gully impacted locations with catchment areas ranging from 10-2 to 10+1 ha. To assess channel geometry and eroded volumes, we used Unmanned Aerial Vehicle and Structure-from-Motion technique. The model successfully estimated long-term erosion rates, its efficiency was 0.77, and it is recommended for catchments up to 8 ha. Therefore, the new model provides planners and stakeholders with a tool to assess gully erosion, sediment yield and geometry in most areas.
Subject(s)
Conservation of Natural Resources , Ecosystem , Conservation of Natural Resources/methods , Entropy , SoilABSTRACT
AIM: To evaluate the influence of an artefact reduction algorithm (ARA) and several root filling materials on the detection of root fractures on cone-beam computed tomography (CBCT) images. METHODOLOGY: Forty-four teeth were divided into control and fractured groups and scanned on a Picasso Trio CBCT device under four conditions: unrestored, filled with gutta-percha cones, cast-gold or fibreglass posts; either with or without applying the ARA. Three calibrated examiners assessed the images. ROC analysis, anova and pairwise Tukey LSD test were performed. RESULTS: No significant difference between the groups with and without the ARA was observed. There was no significant interaction between the algorithm and root condition. On the other hand, there was a significant difference in the mean values of sensitivity (Sn) and accuracy (Ac) amongst the different root filling groups (P ≤ 0.001). CONCLUSIONS: The application of the ARA did not influence the diagnosis of root fractures, and its effects did not depend on root conditions. In relation to the filling materials, gold posts reduced the overall CBCT diagnostic ability, regardless of the use of the ARA.
Subject(s)
Algorithms , Artifacts , Tooth Fractures/diagnosis , Tooth Root , Gutta-Percha , HumansABSTRACT
In the past ten years, three related prostheses (Freeman-Swanson, ICLH, Freeman-Samuelson) have been used at the London Hospital. The new findings reported in this article are the result of cementless fixation of the ICLH prosthesis has not deteriorated with time; the patellofemoral complications and postoperative limitation of movement seen with the ICLH prosthesis has been resolved by the Freeman-Samuelson design; and cementless press-fit fixation of all three components of the Freeman-Samuelson design resulted in a 1.6% (tibial) revision rate in the first four years.
Subject(s)
Knee Prosthesis , Adult , Aged , Evaluation Studies as Topic , Female , Follow-Up Studies , Humans , Knee Joint/physiology , Male , Middle Aged , Movement , Prosthesis DesignSubject(s)
Knee Prosthesis , Adult , Aged , Female , Follow-Up Studies , Humans , Male , Middle Aged , Orthopedic Equipment , Postoperative Complications/etiology , Prospective Studies , Prosthesis Design , Prosthesis FailureABSTRACT
Sao analisados 79 casos de osteomielite aguda hematogenica e o resultado do tratamento na fase inicial. Quatro foram tratados de forma conservadora, 17 com drenagem local e 58 submetidos a instilacao-aspiracao pelo metodo de Compere. Os resultados a curto prazo foram classificados na categoria de "bom" em 56,96% dos pacientes. Os casos de melhor evolucao foram os de criancas entre 0 a 3 anos de idade com bom estado geral e nutritivo, que receberam como medicacao antibiotica a associacao de penicilina cristalina e oxacilina, complementada por dicloxacilina.Os autores alerta, para a necessidade de sistematizacao de atendimento e tratamento dos pacientes e descrevem o protocolo usado em seu servico
