The feeder system of the Toba supervolcano from the slab to the shallow reservoir.

The Toba Caldera has been the site of several large explosive eruptions in the recent geological past, including the world's largest Pleistocene eruption 74,000 years ago. The major cause of this particular behaviour may be the subduction of the fluid-rich Investigator Fracture Zone directly beneath the continental crust of Sumatra and possible tear of the slab. Here we show a new seismic tomography model, which clearly reveals a complex multilevel plumbing system beneath Toba. Large amounts of volatiles originate in the subducting slab at a depth of ∼150 km, migrate upward and cause active melting in the mantle wedge. The volatile-rich basic magmas accumulate at the base of the crust in a ∼50,000 km(3) reservoir. The overheated volatiles continue ascending through the crust and cause melting of the upper crust rocks. This leads to the formation of a shallow crustal reservoir that is directly responsible for the supereruptions.

Peculiar character of dialyzate ultraviolet extinction spectra as an indicator of nucleic acid metabolism in humans.

UV extinction spectra of effluent dialyzate in the process of hemodialysis and peritoneal dialysis are studied. It is found that they have distinctive individual features unique to each patient. The shape of the spectrum remains virtually invariable for a given subject during the whole period of the study (more than a year) and does not depend on the treatment modality or other factors like sex, age, the stage of chronic renal failure, and concomitant illnesses. Absorption bands in two spectral regions--255 to 265 nm and 288 to 298 nm--account for the unique character of dialyzate spectra. Spectra classification based on the ratio of integral extinctions in these regions are introduced. It is assumed that the shape of the spectrum depends on the relative contents of plasma components. Statistical analysis of individual features of spectra for the groups of patients undergoing hemodialysis (78 people) and peritoneal dialysis (42 people) is carried out. It is revealed that the distribution of patients by the ratio of integral extinctions in the specified spectral regions adheres to the normal law. Presumably individual features of spectra could be related to uric acid and a biochemically unidentified substance with an absorption peak near 260 nm.