A note on the von Bertalanffy growth function concerning the allocation of surplus energy to reproduction

We propose an extended form of the von Bertalanffy growth function (VBGF), where the allocation of surplus energy to reproduction is considered. Any function can be used in our model to describe the ratio of energy allocation for reproduction to that for somatic growth. As an example, two models for energy allocation were derived: a step-function and a logistic function. The extended model can jointly describe growth in adult and juvenile stages. The change in growth rate between the two stages can be either gradual or steep; the latter gives a biphasic VBGF. The results of curve fitting indicated that a consideration of reproductive energy is meaningful for model extension. By controlling parameter values, our comprehensive model gives various growth curve shapes ranging from indeterminate to determinate growth. An increase in the number of parameters is unavoidable in practical applications of this new model. Additional information on reproduction will improve the reliability of model estimates

Glides are high vowels in onsets and codas: A case of Southern Vietnamese

Glides, /j/ and /w/, are recognized as semivowels in Vietnamese, and they are conventionally and widely written as /i̯/ and /u̯/, respectively (Phạm & Mcleod 2016, Tran, Vallée & Granjon 2019). The implication of the conventional transcription of the two semivowels is that they are non-syllabic /i/ and /u/, suggesting that /i̯/ and /u̯/ might have similar or nearly identical acoustic properties with the two high vowels /i/ and /u/. As the semivowels are only allowed in onsets and codas, and the vowels are allowed in nuclei (Kirby 2011, Phạm & Mcleod 2016, Brunelle 2017, Tran et al. 2019), the only difference between the two semivowels and the two vowels might be where they can appear. That is, the semivowels might be non-syllabic positional variants of the high vowels that appear in onsets and codas (Levi, 2008). To examine this hypothesis, audio files in which a native female speaker of Southern Vietnamese recites the 200 Swadesh words in her dialect were collected, and the first formant (F1) and the second formant (F2) of each word that contains either /i/, /u/, /i̯/ or /u̯/ were measured using Praat (Boersma & Weenink 2020). Analyses on the F1 showed no significant difference on the F1 between /i/ and /i̯/ (p = .97) or /u/ and /u̯/ (p = .78). Similarly, there was no significant difference on the F2 between /i/ and /i̯/ (p = .91) or /u/ and /u̯/ (p = .91). The results support that /i/ and /i̯/ as well as /u/ and /u̯/ have nearly identical phonetic properties