Early in gestation the fetal heart rate is predominately under the control of the sympathetic nervous system and arterial chemoreceptors [1]. As the fetus develops its heart rate decreases in response to parasympathetic ( vagal stimulation) nervous system maturation and variability becomes more pronounced [2].
Igneous Rocks by Composition Igneous rocks are classified according to their mineral content: Ultramafic rocks are dominated by olivine and/or pyroxene. Mafic rocks are dominated by plagioclase and pyroxene (even if you can't see them with the naked eye) and smaller amounts of olivine.Intermediate rocks are roughly even mixtures of felsic minerals (mainly plagioclase) and mafic minerals (mainly hornblende, pyroxene, and/or biotite).There is little or no quartz. Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and less than 15% mafic minerals (biotite, hornblende).afic rocks are dominated by plagioclase and pyroxene (even if you can't see them with the naked eye) and smaller amounts of olivine. Intermediate rocks are roughly even mixtures of felsic minerals (mainly plagioclase) and mafic minerals (mainly hornblende, pyroxene, and/or biotite).
Definition of intermediate for English Language Learners. : 1  occurring in the middle of a process or series. : 2  relating to or having the knowledge or skill of someone who is more advanced than a beginner but not yet an expert.