Heterogeneous machine learning system for improving the diagnosis of primary aldosteronism

The NZAPLUME III expedition of September–October 2004 to the northern Kermadec–southern Tofua (NKST) arc, between 28°52?S and 25°07?S, resulted in the discovery of at least seven new submarine volcanic centers and a substantial caldera complex adjacent to the previously known Monowai Seamount. The volcanic centers form a sublinear chain that coincides with the Kermadec Ridge crest in the south (Hinetapeka) and diverges ?45 km westward of the ridge crest in the north (“V”) just to the south of where the Louisville Ridge intersects with the arc. All of the centers contain calderas or caldera-like structures, as well as multiple cones, domes, fissure ridges, and vent fields. All show signs of recent eruptive and current hydrothermal activity. There are strong structural controls on edifice location, with cones and fissure ridges typically associated with faulting parallel to the regional ?12° strike of the arc front. Several of the calderas are ellipsoidal, orientated northwest–southeast in the general direction of least compressive stress. Sampled volcanic rocks, representing the most recently erupted lavas, are all low-K tholeiites. Two of the centers, Gamble and Rakahore, yielded only high-silica dacite to rhyolite (69–74 wt% silica), whereas two others, Monowai and “V,” yielded only basalt to andesite (48–63 wt% silica). Mineral assemblages are plagioclase-pyroxene dominated, with accessory Fe-Ti oxides, apatite, olivine, and quartz/tridymite/cristobalite, typical of dry volcanic arc systems. Hornblende occurs only in a felsitic rhyolite from Hinepuia volcanic center, and zircon is absent. Glass contents range to 57% in basalts–andesites (mean 20%), and 97% in andesites–rhyolites (mean 59%) and other quench textures, including swallow-tailed, plumose, or dendritic crystal forms and crystallites, are common. Most lavas are highly vesicular (?63%; mean 28%) and have low volatile contents (mostly &lt;2 wt%) which, together with the occurrence of tridymite or cristobalite, indicates explosive eruption and rapid cooling. Exceptions are rocks from “U” volcanic center, which have low vesicularity and low glass contents across a wide compositional range, indicating effusive eruption. Disequilibrium mineral textures, the frequent occurrence of xenoliths and xenocrysts, and macroscopic evidence for magma mingling indicate that many of the lavas are hybrids, having resided only a short time in upper crustal reservoirs prior to eruption. Silicic magmas are major components of NKST arc volcanism and caldera formation is the dominant eruptive style. The scale of silicic magmatism is in marked contrast to the dominant basaltic–andesitic magmatism in the southern Kermadec arc. With evidence from other arcs, silicic magmatism is now recognized as a major feature of intraoceanic arcs globally. <br/

Heterogeneous machine learning system for improving the diagnosis of primary aldosteronism

We develop a novel classifier for the diagnosis of Aldosterone-Producing Adenoma (APA), which induces Primary Aldosteronism, the most common endocrine cause of curable hypertension. The classifier considerably improves upon the state of the art, and it is devised and tested on a large dataset of patients, each described by several demographic and biochemical features. As customary in real world datasets, ours is affected by feature correlation, missing values, and class imbalance. We make explicit provisions for dealing with all of these issues through an ensemble of ensembles, that is, a multilevel fusion of different component classifiers. Using the Wilcoxon signed rank test at 0.05 significance level, we show that our ensemble significantly outperforms the state-of-the-art classifier and any individual component in the ensemble. Our experiments employ a "leave-one-out-clinical" cross validation as patients were treated in 15 different specialized centers for hypertension; in each fold, 14 centers are used for training and 1 as the test set. Our classifier is available at http://www.dei.unipd.it/node/2357 (MATLAB code)