Modelfree methods for nonparametric estimation of unknown continuous functions from measured values and their advantages as against fitting of analytical expressions are discussed. The main features are stated especially of the empirical regression and of the local adjusted polynomial approximation. These topics and problems of application of the procedures are illustrated by 3 examples coming from chronobiological, neuromorphometrical, and histochemical examinations.
Download full-text PDF |
Source |
---|
Neuroendocrinology
February 2002
Division of Endocrinology and Metabolism, Department of Internal Medicine, Center for Biomathematical Technology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
Somatostatin (SRIH) release into hypophyseal portal blood varies reciprocally with growth hormone (GH) pulse generation in the male rat. However, few studies have directly evaluated this relationship in the female of any species. To address this issue, we carried out intensive (5 min) and extended (240 min) simultaneous monitoring of hypophyseal portal SRIH and internal jugular GH secretion in 7 unanesthetized ewes.
View Article and Find Full Text PDFJ Clin Endocrinol Metab
February 2001
Division of Endocrinology, Department of Internal Medicine, General Clinical Research Center, Center for Biomathematical Technology, University of Virginia School of Medicine, Charlottesville, Virginia 22908-0202, USA.
Plasma bioavailable testosterone concentrations decline in healthy older men without a uniformly commensurate rise in serum LH concentrations, which disparity is consistent with a hypothesis of relative hypogonadotropism. Likewise, preserved gonadotrope responsiveness to exogenous GnRH stimulation, despite an attenuated amplitude of endogenous LH pulses, points to reduced hypothalamic GnRH feedforward signaling in aging males. To appraise GnRH/LH secretory reserve more directly in older men, we have compared daily LH secretion, driven by profound short-term blockade of androgen biosynthesis by oral ketoconazole administration, in nine young (ages, 18-32 yr) and seven older (ages, 60-73 yr) volunteers.
View Article and Find Full Text PDFGegenbaurs Morphol Jahrb
February 1990
Institut für Anatomie des Bereichs Medizin, Martin-Luther-Universität Halle-Wittenberg.
Measurements of endocrinological and pharmacological processes often yield courses of time series with exponentially saturated increasing first part followed by an exponentially decreasing part. Such measured courses may be mathematically modelled by the so-called BATEMAN function type, an expression consisting of 2 e-function terms. In this paper, the method of locally adjusted functional approximation for model-free quantitative evaluation of measured time series is sketched.
View Article and Find Full Text PDFModelfree methods for nonparametric estimation of unknown continuous functions from measured values and their advantages as against fitting of analytical expressions are discussed. The main features are stated especially of the empirical regression and of the local adjusted polynomial approximation. These topics and problems of application of the procedures are illustrated by 3 examples coming from chronobiological, neuromorphometrical, and histochemical examinations.
View Article and Find Full Text PDFGegenbaurs Morphol Jahrb
January 1984
The biomathematical processing of growth data aims the separation of the deterministic variation of the growth variable from the superposed random fluctuations. For the quantitative representation of the deterministic component, 3 possibilities are noted (mean values polygon, empirical regression, and least squares fitting of functions). By 2 examples of measured growth data, the suitability of these approaches will be discussed to give reproducible results and to avoid artifacts.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!