scholarly journals A non-asymptotic sigmoid growth curve for top height growth in forest stands

2012 ◽  
Vol 85 (3) ◽  
pp. 353-368 ◽  
Author(s):  
Jean-Daniel Bontemps ◽  
Pierre Duplat
Keyword(s):  
Growth Curve ◽  
Height Growth ◽  
Forest Stands ◽  
Sigmoid Growth Curve

scholarly journals Growth in achondroplasia, from birth to adulthood, analysed by the JPA-2 model

2020 ◽  
Vol 33 (12) ◽  
pp. 1589-1595
Author(s):  
Mariana del Pino ◽  
Virginia Fano ◽  
Paula Adamo
Keyword(s):  
General Population ◽  
Growth Curve ◽  
Growth Velocity ◽  
Adult Height ◽  
Growth Curves ◽  
Peak Height ◽  
Height Growth ◽  
Individual Growth ◽  
Height Velocity ◽  
Peak Height Velocity

AbstractObjectivesIn general population, there are three phases in the human growth curve: infancy, childhood and puberty, with different main factors involved in their regulation and mathematical models to fit them. Achondroplasia children experience a fast decreasing growth during infancy and an “adolescent growth spurt”; however, there are no longitudinal studies that cover the analysis of the whole post-natal growth. Here we analyse the whole growth curve from infancy to adulthood applying the JPA-2 mathematical model.MethodsTwenty-seven patients, 17 girls and 10 boys with achondroplasia, who reached adult size, were included. Height growth data was collected from birth until adulthood. Individual growth curves were estimated by fitting the JPA-2 model to each individual’s height for age data.ResultsHeight growth velocity curves show that after a period of fast decreasing growth velocity since birth, with a mean of 9.7 cm/year at 1 year old, the growth velocity is stable in late preschool years, with a mean of 4.2 cm/year. In boys, age and peak height velocity in puberty were 13.75 years and 5.08 cm/year and reach a mean adult height of 130.52 cm. In girls, the age and peak height velocity in puberty were 11.1 years and 4.32 cm/year and reach a mean adult height of 119.2 cm.ConclusionsThe study of individual growth curves in achondroplasia children by the JPA-2 model shows the three periods, infancy, childhood and puberty, with a similar shape but lesser in magnitude than general population.

scholarly journals Estimation of change in forest height growth

2017 ◽  
Vol 67 (1) ◽  
pp. 5-16 ◽  
Author(s):  
Mait Lang ◽  
Tauri Arumäe ◽  
Diana Laarmann ◽  
Andres Kiviste
Keyword(s):  
Laser Scanning ◽  
Growth Conditions ◽  
Height Growth ◽  
Forest Growth ◽  
Forest Stands ◽  
Difference Model ◽  
Permanent Sample Plots ◽  
Airborne Laser ◽  
Forest Height ◽  
Algebraic Difference

AbstractForest height increment rate is related to the forest growth conditions. Data bases of previous forest inventories contain information about forest heightage relationship on large number of forest stands while repeated measurements of permanent sample plots provide an excellent reference for comparison. Repeated airborne laser scanning of forest stands is an additional source for the estimation of change in forest structure. In this study, height growth of middle-aged and older forest stands for about 10 year period was compared to an algebraic difference model on permanent sample plots (66) and for a sample of forest stands with repeated airborne laser scanning data (61). The model was based on a large dataset of forest inventory records from the period of 1984–1993. Statistically significant increased forest height growth was found in permanent sample plots based on tree height measurements (9 cm yr−1) as well in stands with repeated laser scanning data (4.5 cm yr−1) in South-East Estonia compared to the algebraic difference model. The difference between the two data sets was explained by their mean age and site class, but the increased forest height growth compared to the old forest inventory data indicates improved growth conditions of forests in the test area. The results hint also that empirical data-based forest growth models need to be updated to avoid biased growth estimates.

scholarly journals Phasic Development of Fagus sylvatica based on 240 Years of Continuous Tree-height Observations

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 582a-582
Author(s):  
F.D. Moore ◽  
S.R. Nath ◽  
Y-C Wang
Keyword(s):  
Growth Rate ◽  
Growth Curve ◽  
Critical Points ◽  
Inflection Point ◽  
Tree Height ◽  
Maximum Growth ◽  
Accurate Estimate ◽  
Height Growth ◽  
Linear Phase ◽  
Maximum Slope

Duration of growth is dependent on morphological events or changes in growth rate. It is the latter that is associated with phasic development. The most productive phase of plant growth is the linear or constant rate phase, primarily because it endures longer than the exponential phase. The purpose of our research was to objectively determine the true tree-height growth pattern, the linear and stationary phases of height growth, and to mathematically derive the maximum slope (maximum growth rate) of the growth curve, its location (inflection point), and the maximum slope of the logarithmic form (maximum relative growth rate) of the growth curve. The data were composed of 333 tree-height records covering 240 years from 200 beechwoods in the U.K. Height-age data were fitted using a splined function (S) and the Chapman-Richards function (CR). The growth curve and critical points on the curve were derived from the CR model. The linear phase began when trees were 9 and lasted 43 years. However, the stationary phase did not begin until age 162. Anecdotal evidence suggests that very little fruiting occurs before age 50. Based on derived critical points and anticipated source-sink dynamics, the reproductive stage should have taken place during the progressive “deceleration phase” when trees were between 31 (location of the maximum slope, also inflection point) and 162 (from quadratic root). The linear phase ended at 52 years, (coinciding with minimum acceleration) and may prove a more accurate estimate than 31. Maximum slope was 1.2 m per year occurring at age 31. Maximum slope of the log curve was 0.14 m·m–1 per year. The advantage of the CR function and the importance of the derived quantities and growth phases will be discussed.

Symphysiofundal height growth curve and growth velocity in pregnant women in a Nigerian community

2009 ◽  
Vol 29 (7) ◽  
pp. 605-608
Author(s):  
L. E. Ebite ◽  
P. N. Ebeigbe ◽  
P. Igbigbi ◽  
F. C. Akpuaka
Keyword(s):  
Pregnant Women ◽  
Growth Curve ◽  
Growth Velocity ◽  
Height Growth

scholarly journals Fundal Height Growth Curve for Thai Women

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Jirawan Deeluea ◽  
Supatra Sirichotiyakul ◽  
Sawaek Weerakiet ◽  
Renu Buntha ◽  
Chamaiporn Tawichasri ◽  
...  
Keyword(s):  
Growth Curve ◽  
Multilevel Model ◽  
Height Growth ◽  
Quadratic Regression ◽  
Singleton Pregnancy ◽  
Maximum Increase ◽  
Thai Women ◽  
Intrauterine Growth ◽  
Time Series Study ◽  
Series Study

Objectives. To develop fundal height (FH) growth curve from normal singleton pregnancy based on last menstrual period (LMP) and/or ultrasound dating for women in the northern part of Thailand. Methods. A retrospective time-series study was conducted at four hospitals in the upper northern part of Thailand between January 2009 and March 2011. FH from 20 to 40 weeks was measured in centimeters. The FH growth curve was presented as smoothed function of the 10th, 50th, and 90th percentiles, which were derived from a regression model fitted by a multilevel model for continuous data. Results. FH growth curve was derived from 7,523 measurements of 1,038 women. Gestational age was calculated from LMP in 648 women and ultrasound in 390 women. The FH increased from 19.1 cm at 20 weeks to 35.4 cm at 40 weeks. The maximum increase of 1.0 cm/wk was observed between 20 and 32 weeks, declining to 0.7 cm/wk between 33 and 36 weeks and 0.3 cm/wk between 37 and 40 weeks. A quadratic regression equation was FH (cm)=-19.7882+2.438157 GA (wk)-0.0262178 GA2 (wk) (R-squared = 0.85). Conclusions. A demographically specific FH growth curve may be an appropriate tool for monitoring and screening abnormal intrauterine growth.

Why do rotifer populations present a typical sigmoid growth curve?

Rotifera IX ◽  
2001 ◽  
pp. 99-105 ◽  
Author(s):  
Tatsuki Yoshinaga ◽  
Atsushi Hagiwara ◽  
Katsumi Tsukamoto
Keyword(s):  
Growth Curve ◽  
Sigmoid Growth Curve

Quasi-fixed Points w.r.t. the Height Growth Curve

1988 ◽  
Vol 30 (2) ◽  
pp. 157-164 ◽  
Author(s):  
M. Masuyama
Keyword(s):  
Fixed Points ◽  
Growth Curve ◽  
Height Growth
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