Clinical and histopathological aspects of 113 necrotizing malignant melanomas of the choroid. 1. Clinical and histological features of necrotizing choroidal melanomas

BACKGROUND: Tumor necrosis may reflect a destructive immune reaction. Systematic and statistically significant comparative clinico-histopathologic studies have not yet been reported. PATIENTS AND METHODS: 113 necrotizing choroidal melanomas (NCM) recruited from 701 enucleated globes 1967-1988 were resectioned, stained and compared to 100 choroidal melanomas without necrosis (CM), and data of 74 patients with a follow-up of more than 10 years were evaluated. RESULTS: Statistically significant characteristics of NCM were: patient age < 60 yrs. for NCM 27.4%, CM 46%; patient age in men for NCM was 64 yrs on average (CM: 58 yrs.), in women for NCM 67 yrs. (CM: 59 yrs.). Time elapsed between first symptoms and enucleation was < 12 months in 15.9% of NCM (89% for CM), and > 12 months in 23.9% of NCM (11% in CM). Mixed or epitheloid cell tumors was seen in 54.9% of NCM and 49% of CM, spindle cell tumors in 36.3% of NCM and 51% in CM. Advanced tumor stages T3 and T4 were present in 45.1% resp. 36.3% of NCM compared to 37% resp. 16% in CM. Scleral invasion was documented in 67.3% of NCM and 37% of CM, extrascleral dissemination in 43% of NCM and 16% of CM. Secondary glaucomas were seen in 62.2% of NCM and 6% CM, a penetration through Bruch's membrane in 61.0% of NCM and 46% of CM. Intratumoral hemorrhage was noted in 68.14% of NCM and 24% of CM, extratumoral bleeding in 23.9% of NCM and 0% CM. Inflammatory reactions in tumors were observed in 96.7% of NCM harboring > 30% necrosis compared to 5% in CM, and extratumoral in 94.5% of NCM and 0% of CM. Intraocular extratumoral necrosis was seen in 23.9% of NCM and 0% of CM. There were no significant differences in the degree of pigmentation of the 90.3% pigmented NCM or of the 94% pigmented CM, neither in the tumor localization, being constantly behind the equator in 87% of cases. Survival of patients with NCM patients was 5 years and 9 months on average (5-year mortality rate 41.9%), and 74.3% were deceased from metastatic spread. CONCLUSIONS: Significant clinical and histopathological differences between necrotizing and non-necrotizing malignant melanomas of the choroid can be identified. The inflammatory reaction of NCM must be further elucidated, particularly with respect to the nature of tumor-infiltrating lymphocytes.     

Necrotizing keratitis in chronic polyarthritis. Combined immunosuppressive and surgical therapy

Degenerative changes of the retropatellar articular surface contribute to a great extent to functional disability in patients with osteoarthritic knees. Therefore, in the present study we examined the influence of retropatellar osteoarthritis (OA) on proprioception in patients with knee OA. Comparison of movement sense determined by threshold levels for the perception of knee motion was performed in 10 patients with severe, in 10 patients with moderate, and in 9 patients with mild retropatellar OA. In addition, detection failures occurring during movement sense measurements were analysed. At correct movement detections, threshold levels did not differ between the three groups of patients regardless the extent of retropatellar OA. In contrast, analysis of detection failures occurring during movement sense measurements revealed significantly higher failure rates with greater severity of retropatellar OA. In conclusion, our study gives evidence for increased proprioceptive deficits with greater severity of retropatellar articular surface damage. Hereby, analysis of detection failures occurring during movement sense measurements proved to be a feasible tool for the assessment of proprioceptive deficits.     

Robustness of unmodified stochastic adaptive control algorithms

Originally, adaptive control theory was developed for the ideal system models, i.e., linear system models under the assumption that relative degree and upper bounds on the order of the systems are known. In the early 1980s, adaptive control algorithms designed for such ideal system models were strongly attacked by many researchers due to “lack of robustness” in the presence of unmodeled dynamics and external disturbances. The purpose of the present paper is to relax existing constant pressure on the adaptive control algorithms originally designed for the ideal system models. It is shown that such adaptive control algorithms are globally stable and robust with respect to unmodeled dynamics and external disturbances without any modifications, such as iσ-modification, ϵ₁-modification, relative dead-zone, projection of the parameter estimates, etc. Global stability of the unmodified algorithms is established by requiring the reference signal to be persistently exciting     

Using Wavelet Analysis to Assess Turbulence/Rotor Interactions

Large loading events on wind turbine rotor blades are often associated with transient bursts of coherent turbulent energy in the turbine inflow. These coherent turbulent structures are identified as peaks in the three‐dimensional, instantaneous, turbulent shearing stress field. Such organized inflow structures and the accompanying rotor aeroelastic responses typically have timescales of only a few seconds and therefore do not lend themselves to analysis by conventional Fourier spectral techniques. Wavelet analysis offers the ability to study more closely the spectral decomposition of short‐period events such as the interaction of coherent turbulence with a moving rotor blade. In this paper we discuss our initial progress in the application of wavelet analysis techniques to the decomposition and interpretation of turbulence/rotor interaction. We discuss the results of using both continuous and discrete wavelet transforms for our application. Several examples are given of the techniques applied to both observed turbulence and turbine responses and those generated using numerical simulations. We found that the presence of coherent turbulent structures, as revealed by the inflow Reynolds stress field, is a major contributor to large load excursions. These bursts of coherent turbulent energy induce a broadband aeroelastic response in the turbine rotor as it passes through them. Copyright © 2001 John Wiley & Sons, Ltd.     

Renewable Energy Systems With Photovoltaic Power Generators: Operation and Modeling

A substantial increase of photovoltaic (PV) power generators installations has taken place in recent years, due to the increasing efficiency of solar cells as well as the improvements of manufacturing technology of solar panels. These generators are both grid-connected and stand-alone applications. We present an overview of the essential research results. The paper concentrates on the operation and modeling of stand-alone power systems with PV power generators. Systems with PV array-inverter assemblies, operating in the slave-and-master modes, are discussed, and the simulation results obtained using a renewable energy power system modular simulator are presented. These results demonstrate that simulation is an essential step in the system development process and that PV power generators constitute a valuable energy source. They have the ability to balance the energy and supply good power quality. It is demonstrated that when PV array- inverters are operating in the master mode in stand-alone applications, they well perform the task of controlling the voltage and frequency of the power system. The mechanism of switching the master function between the diesel generator and the PV array-inverter assembly in a stand-alone power system is also proposed and analyzed. Finally, some experimental results on a practical system are compared to the simulation results and confirm the usefulness of the proposed approach to the development of renewable energy systems with PV power generators.