65 research outputs found
Cardiac transplantation and mechanical circulatory support
No full textCardiac transplantation is the treatment of choice for selected patients with advanced heart failure: median survival exceeds 10 years and recipients enjoy an excellent quality of life, but availability is severely limited by shortage of donor organs. The need for lifelong immunosuppression is associated with side effects, including an increased incidence of malignancy. Newer immunosuppressive agents offer promise in reducing nephrotoxicity of conventional regimens and in delaying the onset of (currently inevitable) cardiac allograft vasculopathy....</p
Listing criteria for heart transplantation: International Society for Heart and Lung Transplantation guidelines for the care of cardiac transplant candidates--2006
No full textEnergy yield simulations of perovskite/c-Si tandem modules in real-world conditions
No full textPerformance of photovoltaic modules are widely expressed using their efficiency at Standard Test Conditions (STC). Although, real world conditions largely differ from this standard. Energy yield of photovoltaic modules at a certain location gives a clear indication of the performance of the module exposed to varying weather conditions. Photovoltaic Materials and Devices (PVMD) Toolbox developed at Delft University of Technology and implemented in MATLAB®, aims to simulate energy yield of photovoltaic modules while providing the flexibility of modifying cell-level to module-level parameters of the device. Accurately determining the irradiance falling on the module at a certain location and simulating the electrical properties of a solar cell at realistic conditions is crucial in determining the yield generated by a module. Due to the promising results displayed by the technology, in this study, energy yield of perovskite/c-Si tandem modules are simulated using newly developed daylight and parameter extraction models in PVMD toolbox. Due to high computational efficiency and functionality offered, Preetham daylight model is implemented as an improvement to Perez model currently used in PVMD toolbox. The model considers the effect of Rayleigh and Mie scattering, and turbidity of atmosphere in determining the distribution of diffuse irradiance across the skydome. By implementing the model, three factors can now be determined: luminance distribution, RGB co-ordinates and relative spectral power distribution over the skydome for any location. Luminance is calculated for every point in sky using Perez parametric function that use coefficients derived from simulated data for different sun directions and turbidity values. For all locations considered, Preetham model calculates higher luminance over the year by ~2%. Calculated luminance values normalized against zenith luminance is used to derive CIE xyY values and consecutively, the RGB co-ordinates that are rendered real-time to create images of the skydome for every hour in chosen timeframe. By calculating the relative spectral power distribution, analysis of incident light falling on the module from all points of the skydome is possible which especially deems useful for modelling tandem modules. To accurately simulate electrical properties of solar cell under varying operating conditions, parameter extraction model for simulated ASA J-V curves is implemented using an analytical method. For the c-Si and perovskite cells considered in the study, the reconstructed curves using extracted parameters fits ASA curve with RMSE or 1.98% and 3.02% respectively at STC. Using these models introduced in this study, energy yield of mono-facial and bi-facial 2T/4T tandem modules are calculated and analyzed for Rome, Reykjavik and Alice Springs. Depending on air mass of a location, perovskite thickness of mono-facial 2T tandem devices are optimized to produce maximum specific yield. All considered modules generate highest yield at Alice Springs due to high insolation at the location. The yield difference between modules while using the two daylight models is insignificant at <1%. With an increase in perovskite thickness, energy yield of 2T bi-facial modules increase significantly for high albedo while it drops beyond the optimum thickness due to current mismatch for low albedo. Bi-facial 4T module on high albedo (albedo= 0.85) surfaces show best performance out of all the modules producing 36% higher yield than mono-facial 4T module for Rome.Electrical Engineering | Sustainable Energy Technolog
Malignancy after Heart Transplantation: Analysis of 24-Year Experience at a Single Center
No full textBackground: Malignancy is an important complication after heart transplantation. The incidence, spectrum, risk factors, and clinical impact of posttransplant malignancy were investigated in a cohort of patients with long-term follow-up at a single center. Methods: Data for 835 patients who underwent heart transplantation between 1979 and 2002 and survived beyond one month were retrospectively evaluated for posttransplant skin cancer, solid organ tumors, and lymphoma. Results: One hundred thirty-ninemalignancies developed in 126 patients (15.1%). Skin cancer, solid organ tumors, and lymphoma represented 49%, 27%, and 24% of the malignancies, respectively. Mean patient age at transplantation for patients developing skin cancer, solid organ tumor, and lymphoma were 50 years, 51 years, and 46 years, respectively (p = 0.024). Risk factors for skin cancer were: age greater than 40 at transplantation, number of treated rejection episodes in the first year after transplantation, and smoking history. Variables associated with solid organ malignancy development were age and smoking history. There was no variable related to the development of posttransplant lymphoma. Median survival after diagnosis of skin cancer, solid organ tumor, and lymphoma were 5.0 years, 0.3 years, and 0.7 years, respectively (p < 0.001). Conclusions: Posttransplant malignancies have different risk factors and variable clinical impact. Older age at transplantation, smoking history, and more episodes of treated rejection were related to increased incidence of nonlymphoid malignancy incidence after heart transplantation, whereas no variable was associated with lymphoid malignancy. Skin cancers have a benign course, while solid organ malignancies and lymphomas carry an unfavorable prognosis. doi: 10.1111/j.1540-8191.2009.00858.x (J Card Surg 2009; 24: 572-579
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