Mathematical models to describe the growth curves of Vietnamese Ri chicken

Ri chicken is the most popular backyard chicken breed in Vietnam, but little is known about the growth curve of this breed. This study compared the performances of models with three parameters (Gompertz, Brody, and Logistic) and models containing four parameters (Richards, Bridges, and Janoschek) for describing the growth of Ri chicken. The bodyweight of Ri chicken was recorded weekly from week 1 to week 19. Growth models were fitted using minpack.lm package in R software and Akaike’s information criterion (AIC), Bayesian information criterion (BIC), and root mean square error (RMSE) were used for model comparison. Based on these criteria, the models having four parameters showed better performance than the ones with three parameters, and the Richards model was the best one for males and females. The lowest and highest value of asymmetric weights (α) were obtained by Bridges and Brody models for each of sexes, respectively. Age and weight estimated by the Richard model were 8.46 and 7.51 weeks and 696.88 and 487.58 g for males and for females, respectively. Differences in the growth curves were observed between males and female chicken. Overall, the results suggested using the Richards model for describing the growth curve of Ri chickens. Further studies on the genetics and genomics of the obtained growth parameters are required before using them for the genetic improvement of Ri chickens.

Cue-induced cocaine craving enhances psychosocial stress and vice versa in chronic cocaine users

There is evidence that stress and craving contribute to the development, maintenance, and relapse in cocaine use disorder. Previous research has shown altered physiological responses to psychosocial stress as well as increased vegetative responding to substance-related cues in chronic cocaine users (CU). However, how psychosocial stress and cue-induced craving interact in relation to the physiological response of CU is largely unknown. Therefore, we investigated the interaction between acute psychosocial stress and cocaine-cue-related reactivity in 47 CU and 38 controls. Participants were randomly exposed first to a video-based cocaine-cue paradigm and second to the Trier Social Stress Test (TSST) or vice versa in a crossed and balanced design to investigate possible mutually augmenting effects of both stressors on the physiological stress response. Plasma cortisol, ACTH, and noradrenaline as well as subjective stress and craving were assessed repeatedly over the course of the experimental procedure. Growth models and discontinuous growth models were used to estimate the responses during the cocaine-cue paradigm and TSST. Overall, both groups did not differ in their endocrinological responses to the TSST but CU displayed lower ACTH levels at baseline. The TSST did not elevate craving in CU. However, if the cocaine-cue video was shown first, CU displayed an enhanced cortisol response to the subsequent TSST. Cocaine-cues robustly evoked craving in CU but no stress response, while cue-induced craving was intensified after the TSST. Taken together, CU did not show an altered acute stress response during the TSST but stress and craving together seem to have mutually augmenting effects on their stress response.

Growth Parameters and Spawning Season Estimation of Four Important Flyingfishes in the Kuroshio Current Off Taiwan and Implications From Comparisons With Global Studies

Growth shapes the life history of fishes. Establishing appropriate aging procedures and selecting representative growth models are important steps in developing stock assessments. Flyingfishes (Exocoetidae) have ecological, economic, and cultural importance to many coastal countries including Taiwan. There are 29 species of flyingfishes found in the Kuroshio Current off Taiwan and adjacent waters, comprising 56% of the flyingfishes taxa recorded worldwide. Among the six dominant species in Taiwan, four are of special importance. This study reviews aging data of these four species, documents major points of the aging methods to address three aging issues identified in the literature, and applies multi-model inference to estimate sex-combined and sex-specific growth parameters for each species. The candidate growth models examined included von Bertalanffy, Gompertz, Logistic, and Richards models, and the resulting optimal model tended to be the von Bertalanffy model for sex-combined data and Gompertz and von Bertalanffy models for sex-specific cases. The study also estimates hatch dates from size data collected from 2008 to 2017; the results suggest that the four flyingfishes have two spawning seasons per year. Length-weight relationships are also estimated for each species. Finally, the study combines the optimal growth estimates from this study with estimates for all flyingfishes published globally, and statistically classifies the estimates into clusters by hierarchical clustering analysis of logged growth parameters. The results demonstrate that aging materials substantially affect growth parameter estimates. This is the first study to estimate growth parameters of flyingfishes with multiple model consideration. This study provides advice for aging flyingfishes based on the three aging issues and the classification analysis, including a recommendation of using the asterisci for aging flyingfishes to avoid complex otolith processing procedures, which could help researchers from coastal countries to obtain accurate growth parameters for many flyingfishes.

Modelling the artificial forest (<i>Robinia pseudoacacia</i> L.) root–soil water interactions in the Loess Plateau, China

Plant root–soil water interactions are fundamental to vegetation–water relationships. Soil water availability and distribution impact the temporal–spatial dynamics of roots and vice versa. In the Loess Plateau (LP) of China, where semi-arid and arid climates prevail and deep loess soil dominates, drying soil layers (DSLs) have been extensively reported in artificial forestland. While the underlying mechanisms that cause DSLs remain unclear, they hypothetically involve root–soil water interactions. Although available root growth models are weak with respect to simulating the rooting depth, this study addresses the hypothesis of the involvement of root–soil water interactions in DSLs using a root growth model that simulates both the dynamic rooting depth and fine-root distribution, coupled with soil water, based on cost–benefit optimization. Evaluation of field data from an artificial black locust (Robinia pseudoacacia L.) forest site in the southern LP positively proves the model's performance. Further, a long-term simulation, forced by a 50-year climatic data series with varying precipitation, was performed to examine the DSLs. The results demonstrate that incorporating the dynamic rooting depth into the current root growth models is necessary to reproduce soil drying processes. The simulations revealed that the upper boundary of the DSLs fluctuates strongly with infiltration events, whereas the lower boundary extends successively with increasing rooting depth. Most infiltration was intercepted by the top 2.0 m layer, which was the most active zone of infiltration and root water uptake. Below this, the percentages of fine roots (5.0 %) and water uptake (6.2 %) were small but caused a persistently negative water balance and consequent DSLs. Therefore, the proposed root–water interaction approach succeeded in revealing the intrinsic properties of DSLs; their persistent extension and the lack of an opportunity for recovery from the drying state may adversely affect the implementation of artificial afforestation in this region as well as in other regions with similar climates and soils.

Rapid eutectic growth: from rod growth to diffusionless solidification

Numerous experimental data on the rapid solidification of eutectic systems exhibit the formation of metastable solid phases with the initial (nominal) chemical composition. This fact is explained by the suppression of eutectic decomposition due to diffusionless (chemically partitionless) solidification beginning at a high but finite growth velocity of crystals. In the present work, a model is suggested for the diffusionless growth to analyse the atomic diffusion in the rod eutectic couples growing into supercooled liquid. A simplified calculating method for the equation related to the Bessel function in the solution of the growth of rod eutectics is obtained. This method can also be used in the calculation of other rod eutectic growth models. This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’.

Institutionalizing Inclusive Markets as a Prerequisite to Inclusive Growth

This article questions the contemporary definitions given to the concept of inclusive growth, which is assumed to be an effective solution to the problems of exclusion (marginalization, unemployment, poverty, inequality, etc.), without designing new growth models and without putting in place the tools necessary for inclusion (regulation, institutions, capacities, etc.). In the authors' view, the current exclusionary model is far from generating real inclusion as long as it fails to promote the necessary institutions to produce real inclusion and the ability to deal with the different forms of “exclusion.”