Influences of Adoptive Mother and Father’s Parenting and Child’s Temperament on Adoptees’ Social Skills: A Hybrid Dyadic Analysis

Adoption provides a unique opportunity to study the simultaneous effect on adoptees’ development of environmental influences related to adoptive parenting, and children’s biology-based characteristics. In this paper, two Hybrid Dyadic Models were tested to study the mediational role of the adoptees’ negative reactivity on the relationship between mothers and fathers’ supportive (Model A) and unsupportive (Model B) parenting, and adoptees’ social skills. In a sample of 102 couples, mothers and fathers’ reports on adoptees’ social skills, the adoptees’ negative reactivity, and supportive/unsupportive parenting were explored. Supportive/unsupportive parenting was assessed individually (mothers and fathers separately), whereas the adoptees’ negative reactivity and social skills were treated as common fate variables, with both parents’ scores as indicators of a latent construct. Results were non-significant for Model A. Regarding Model B, different relation patterns between unsupportive parenting and social skills were found, depending on whether it was the mother's or the father's parenting. The child's negative reactivity mediated the relationship between the father's (not the mother's) unsupportive parenting and the child's social skills. With information from both parents and considering simultaneously their unique and shared perspectives, this study advances adoption research and strengthens the relevance of dyadic analyses when studying the adoptive family dynamics.

Exploring the interplay of dopaminergic genotype and parental behavior in relation to executive function in early childhood

Child genotype is an important biologically based individual difference conferring differential sensitivity to the effect of parental behavior. This study explored dopaminergic polygenic composite × parental behavior interactions in relation to young children’s executive function. Participants were 135 36-month-old children and their mothers drawn from a prospective cohort followed longitudinally from pregnancy. A polygenic composite was created based on the number of COMT, DAT1, DRD2, and DRD4 alleles associated with increased reward sensitivity children carried. Maternal negative reactivity and responsiveness were coded during a series of structured mother–child interactions. Executive function was operationalized as self-control and working memory/inhibitory control. Path analysis supported a polygenic composite by negative reactivity interaction for self-control. The nature of the interaction was one of diathesis-stress, such that higher negative reactivity was associated with poorer self-control for children with higher polygenic composite scores. This result suggests that children with a higher number of alleles may be more vulnerable to the negative effect of negative reactivity. Negative reactivity may increase the risk for developing behavior problems in this population via an association with poorer self-control. Due to the small sample size, these initial findings should be treated with caution until they are replicated in a larger independent sample.

Validation of Evaluation Method of Feedback Reactivity for Plant Dynamics Analysis Code During Unprotected Loss of Heat Sink Event in Sodium-Cooled Fast Reactors

Negative reactivity caused by radial expansion of the core is known as one of the inherent safety features in a sodium-cooled fast reactor (SFR). In this paper, the numerical results of the benchmark analyses for the unprotected loss of heat sink (ULOHS) tests in the pool-type experimental SFR in the United States, EBR-II (BOP-302R and BOP-301) are discussed in order to validate the evaluation method of the reactivity feedback equipped in the in-house plant dynamics analysis code named Super-COPD. During the transient of the ULOHS tests as one of the representative issues, the reactor power decreased to the decay heat level due to the negative reactivity caused by the radial expansion of the core. By comparing the numerical results and the experimental data, the profiles of the increase of the core inlet temperature and the decrease of the reactor power calculated by Super-COPD were comparable with those of the experimental data. Applicability of the evaluation method for the reactivity feedback was indicated during the ULOHS event. The refinement of the plenum model of the cold pool by taking account of the thermal stratification was indicated for the future work in order to improve the profile of the core inlet temperature.

Improved FAST Device for Inherent Safety of Oxide-Fueled Sodium-Cooled Fast Reactors

The floating absorber for safety at transient (FAST) was proposed as a solution for the positive coolant temperature coefficient in sodium-cooled fast reactors (SFRs). It is designed to insert negative reactivity in the case of coolant temperature rise or coolant voiding in an inherently passive way. The use of the original FAST design showed effectiveness in protecting the reactor core during some anticipated transients without scram (ATWS) events. However, oscillation behaviors of power due to refloating of the absorber module in FAST were observed during other ATWS events. In this paper, we propose an improved FAST device (iFAST), in which a constraint is imposed on the sinking (insertion) limit of the absorber module in FAST. This provides a simple and effective solution to the power oscillation problem. Here, we focus on an oxide fuel-loaded SFR that is characterized by a more negative Doppler reactivity coefficient and higher operating temperature than the metallic-loaded SFR cores. The study is carried out for the 1000 MWth advanced burner reactor with an oxide fuel-loaded core during postulated ATWS events that are unprotected transient over power, unprotected loss of flow, and unprotected loss of the heat sink. It was found that the iFAST device has promising potentials for protecting the oxide SFR core during the various studied ATWS events.

Early Temperamental Reactivity and Infants’ Responses to Novel Foods at 6 Months of Age

Objectives Since infant food acceptance is linked to diet quality and the development of food preferences, it is important to identify factors related to infants’ reactions to new foods. Temperament, or biologically-based differences in reactivity, has been associated with responses to new foods in childhood, but less research has focused on infancy. The objective of this study was to examine associations between infant temperament at 4 months and responses to new foods at 6 months. Methods Mother-infant dyads (n = 78; 62% male; 97% non-Hispanic white) participated in study visits when infants were 4 and 6 months of age. At 4 months, infants were video-recorded during tasks designed to elicit temperamental reactivity: 1) viewing 3 mobiles (containing 1, 3, and 7 stuffed bears) for 60 seconds each; and 2) listening to a recording of nonsense syllables spoken at 3 different volumes (Kagan & Snidman, 1991). Trained coders scored the presence of negative reactivity (i.e., crying) in 5-second intervals. An experimenter also rated the child's happiness and irritability during the visit on 9-point scales. At 6 months, mothers fed infants a new food (green beans or hummus). Trained coders scored the presence of negative affect (crying, fussing), positive behaviors (e.g., smiling, leaning forward), and food refusals (e.g., turning head) in 5-second intervals. Coded behaviors were summed and divided by the number of coded intervals. Results Regression models were used to test whether temperament (i.e., negative reactivity, happiness, and irritability) at 4 months predicted responses to the new food at 6 months. After controlling for age of solid food introduction (weeks), greater observed negative reactivity at 4 months was associated with more food refusals at 6 months (β = .30, p = .01). Higher happiness scores at 4 months were associated with less negative affect in response to the new food at 6 months (β = −.30, p = .01). Conclusions Temperamentally negative infants may be at risk for difficulties accepting new foods at the beginning of complementary feeding. Parents of these infants could benefit from strategies, such as repeated exposure, to increase new food acceptance. Future research should examine whether early difficulties with food acceptance persist across infancy and beyond. Funding Sources National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

Age-related enhancements in positive emotionality across the lifespan: structural equation modelling of brain and behaviour

Ageing is associated with a bias in attention and memories towards positive and away from negative emotional content. In addition, emotion regulation appears to improve with age, despite concomitant widespread cognitive decline coupled with gray matter volume loss in cortical and subcortical regions thought to sub-serve emotion regulation. Here, we address this emotion-aging paradox using the behavioural data of an emotion regulation task from a population derived sample (CamCAN) and utilise Structural Equation Modelling together with multivariate analysis of structural MRI images of the same sample to investigate brain-behaviour relationships. In a series of measurement models, we show the relationship between age and emotionality is best explained by a four-factor model, compared to single and hierarchical factor models. These four latent factors are interpreted as Basal Negative Affect, Positive Reactivity, Negative Reactivity and Positive Regulation (upregulating positive emotion to negative content). Increasing age uniquely contributes to increased Basal Negative Affect, Positive Reactivity and Positive Regulation, but not Negative Reactivity. Furthermore, we show gray-matter volumes, namely in the bilateral frontal operculum, medial frontal gyrus, bilateral hippocampal complex, bilateral middle temporal gyri and bilateral angular gyrus, are distinctly related to these four latent factors. Finally, we show that a subset of these brain-behaviour relationships remain significant when accounting for age and demographic data. Our results support the notion of an age-related increase in basal emotionality together with a positivity bias and are interpreted in the context of the Socioemotional Selectivity Theory of improved emotion regulation in older age.

ANALYSIS OF MODIFIED PASSIVE SAFETY SYSTEM IN FAST RECTORS TRANSIENTS

The Autonomous Reactivity Control (ARC) system is a passive safety system aiming to provide an additional negative reactivity feedback during reactor transient scenarios. This paper shows how the performance of the ARC system can be enhanced by introducing a hydraulic diode that allows for different engagement and disengagement speeds of system. The benefits of the proposed system is assessed in a reference soidum-cooled fast reactor (SFR) during multiple postulated transient scenarios. The reactor and plant dynamic response are evaluated using SAS4A/SASSYS-1, whereas for the internal ARC system fluid dynamics, the SAM code is adopted. The two codes are externally coupled using a custom driver script which coordinates data exchange and restart calculations at each time step, with Picard iterations used to converge each time step. All the transients analyzed in this work show that the enhanced ARC system is effective in reducing peak temperatures and in reducing the oscillatory behavior encountered in some cases with the standard ARC system.

IMPLEMENTATION OF AN AUTONOMOUS REACTIVITY CONTROL SYSTEM IN A SMALL LEAD-COOLED FAST REACTOR

This paper describes the design, implementation and characterisation of an Autonomous Reactivity Control (ARC) system in a small modular lead-cooled fast reactor. The aim of this work was to demonstrate the applicability of the ARC system and to study its dynamic behaviour during an anticipated transient without scram. A simplified one-dimensional model was developed to calculate the heat transfer within the ARC system, and the reactivity worth as a function of the neutron poison’s insertion into the active core was obtained via static neutronic calculations. By coupling the aforementioned models, the ARC’s time-dependent reactivity was derived as a function of the coolant outlet temperature variation. This model was implemented into the BELLA multi-point dynamics code and transient simulations were run. A control rod ejection accident was studied leading to an unprotected transient overpower scenario, in which 350 pcm reactivity was inserted during one second. It was shown that the ARC system provides a forceful negative reactivity feedback and that steady-state temperatures after the transient were reduced by almost 300 K compared to an identical transient without its action. In this scenario, the ARC system managed to stabilise the coolant outlet temperature at a value 100 K above nominal conditions. The implementation of an ARC system provided the reactor with a passively actuated self-regulating reactivity control system able to insert large amounts of negative reactivity in a short amount of time.