RESUMO
In H-mode tokamak plasmas, the plasma is sometimes ejected beyond the edge transport barrier. These events are known as edge localized modes (ELMs). ELMs cause a loss of energy and damage the vessel walls. Understanding the physics of ELMs, and by extension, how to detect and mitigate them, is an important challenge. In this paper, we focus on two diagnostic methods-deuterium-alpha (Dα) spectroscopy and Doppler backscattering (DBS). The former detects ELMs by measuring Balmer alpha emission, while the latter uses microwave radiation to probe the plasma. DBS has the advantages of having a higher temporal resolution and robustness to damage. These advantages of DBS diagnostic may be beneficial for future operational tokamaks, and thus, data processing techniques for DBS should be developed in preparation. In sight of this, we explore the training of neural networks to detect ELMs from DBS data, using Dα data as the ground truth. With shots found in the DIII-D database, the model is trained to classify each time step based on the occurrence of an ELM event. The results are promising. When tested on shots similar to those used for training, the model is capable of consistently achieving a high f1-score of 0.93. This score is a performance metric for imbalanced datasets that ranges between 0 and 1. We evaluate the performance of our neural network on a variety of ELMs in different high confinement regimes (grassy ELM, RMP mitigated, and wide-pedestal), finding broad applicability. Beyond ELMs, our work demonstrates the wider feasibility of applying neural networks to data from DBS diagnostic.
RESUMO
BACKGROUND: There is a high rate of Toxoplasma gondii infection worldwide. In Latin America the rate is as high as 65% in some populations. AIM: To measure the prevalence of antibodies against Toxoplasma gondii in a native Yucpa community in Venezuela. SUBJECTS AND METHOD: Total serum antibodies measured by indirect hemagglutination and IgM antibodies by ELISA were measured in 94 Yucpa subjects (49 males), aged from 3 months to 100 years. RESULTS: The overall prevalence of infection was 63%. Fifty nine subjects had total antibodies and 14 had IgM antibodies. No significant differences by age or sex, were observed in the proportion of subjects with positive total or IgM antibodies. CONCLUSIONS: The studied individuals had a high prevalence of Toxoplasma gondii infection.