Visual Steering and Verification of Mass Spectrometry Data Factorization in Air Quality Research.

The study of aerosol composition for air quality research involves the analysis of high-dimensional single particle mass spectrometry data. We describe, apply, and evaluate a novel interactive visual framework for dimensionality reduction of such data. Our framework is based on non-negative matrix factorization with specifically defined regularization terms that aid in resolving mass spectrum ambiguity. Thereby, visualization assumes a key role in providing insight into and allowing to actively control a heretofore elusive data processing step, and thus enabling rapid analysis meaningful to domain scientists. In extending existing black box schemes, we explore design choices for visualizing, interacting with, and steering the factorization process to produce physically meaningful results. A domain-expert evaluation of our system performed by the air quality research experts involved in this effort has shown that our method and prototype admits the finding of unambiguous and physically correct lower-dimensional basis transformations of mass spectrometry data at significantly increased speed and a higher degree of ease.

[Cardiodepressive action of bencyclan (author's transl)]. / Die kardiodepressive Wirkung des Bencyclans

In the isolated guinea pigs atria as well as in anaesthetized cats and dogs we studied the cardiovascular effects of bencyclan. The following results were found: 1.) Bencyclan causes a dose-dependent diminution of the force of contraction, the maximal rate of rise of contraction, and the frequency of the isolated atria, while the functional refractory period is prolonged. 2.) The negative inotropic effect of bencyclan can be antagonized in the isolated atria by increasing Ca+++ -concentrations. 3.) In the isolated left atria the effect of orciprenaline is unchanged while the effect of serotonin is diminished by bencyclan. 4.) In the anaesthetized cat 5 mg/kg of bencyclan cause a significant decrease of blood-pressure and contractility. While the fall of blood-pressure is reversed within a few minutes, the contractility is diminished for a longer time. 5.) 2 of 10 cats and 2 of 3 dogs died within a few minutes when 5 mg/kg bencyclan and 1 mg/kg propranolol were injected within an interval of 15 minutes. 6.) Pretreatment with 20 mg/kg propranolol i.m. does not increase the acute toxicity of bencyclan in mice significantly.