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Biomedical subjects

J J Breen

Publications and source records attributed to J J Breen.

23 records · Page 2Linked to original sources
PubMed1966

Simulated Low-gravity Environments and Respiratory Metabolism in Avena Seedlings.

Using horizontal and vertical axis clinostats and sand-grown oat seedlings (Avena sativa), it was found that horizontal clinostat rotation at 2 rpm increased respiration and inorganic and organic phosphorus content of seedlings. Increased coleoptile geotropism and root growth are attributed to rotational nullification of the directional component of the gravitational stimulus. These growth modifications are mechanistically explicable by the relationship between plant metabolism and auxin concentration in these organs.

Journal Article↗
PubMedDate not supplied

Correlation of graph-theoretical parameters with biological activity.

Ośmialowski and Kaliszan calculated graph-theoretical indices for substituted isonicotinic hydrazides and used simple and multiple regression to search (unsuccessfully) for correlations with biological activity. The present paper describes successful searches for correlation in the same data set using principal component analysis (PCA) with multivariate outlier testing and also using stepwise multiple regression. Following PCA, correlation with biological activity always appeared in the second principal component, not the first, that is, after projection of the data points into the (n - 1)-space orthogonal to the first principal component axis. In that space, the principal component score was a more accurate predictor of biological activity than were equations provided by multiple regression or stepwise multiple regression using the underlying variables. A multivariate outlier test identified one observation as discordant, and removing that observation improved prediction further.

Data Interpretation, Statistical↗