Child directed speech: impact of variations in speaking-rate on word learning

This study investigated how caregivers modulate their speaking rate according to children’s lexical knowledge and the context of the interaction, and how such adjustments affect children’s word learning. We studied a seminaturalistic corpus where caregivers talked about different toys with their 3-4 years old children. The toys were known or unknown to the child, and present or absent from the environment. We found that caregivers talked about unknown toys with a slower speaking rate than known ones. When toys were absent, caregivers also tended to slow down for the toy’s name, although they produced the whole utterance faster. Crucially, the results of a subsequent recognition task for children showed that caregivers’ greater adjustment in speaking rate between known and unknown words predicted better immediate learning. Our findings suggest that caregivers modify their speaking rate in a helpful manner when the situation is more demanding, which assists children in word learning

Possible usefulness of echocardiographic Z-scores in autopsy routine of the foetal great vessels

Background: Abnormal diameters of foetal vessels are common findings in congenital heart defects. However, it is difficult for pathologist to assess whether the diameters of the vessels are normal or not and to compare with echocardiographic data. The Z-score is a dimensionless quantity representing the distance between the raw score and population mean in standard deviation units. Using Z-score, we can compare single cases to average standards in the population. Aim: To compare diameters of great arteries measured in specimens fixed in 10% formalin solution to normal values obtained on echocardiography using Z-scores. Material and methods: The study was performed on 43 formalin-fixed normal foetal hearts aged from 19 to 40 weeks of gestation. Each specimen was dissected and the following diameters were measured: aortic valve (AoV), ascending aorta (AAo), descending aorta (DAo), aortic isthmus (AoI), ductus arteriosus (DA), pulmonary trunk valve (PV), and pulmonary arteries (RPA and LPA). Z-score parameters were calculated for all structures using the Foetal Echo Z-score Calculator. Results: Z-score values of all measured foetuses were mostly found to fit within the echocardiographic norms, although the most reliable results were obtained for foetuses aged 23 weeks. This group was represented by the highest number of specimens. The minimal and maximal Z-score values were, respectively: AoV –3.45, 1.4; AAo –4.24, –0.11; DAo –2.12, 1.29; PV –3.21, 0.69; RPA –3.4, 0.84; LPA –2.25, 0.31; AoI –1.97, 0.96; DA –3.56, –1.52. Conclusions: The diameters of great arteries measured on autopsy are comparable to the results obtained from echocardiographic measurement. Z-score values for foetal echocardiography can be applied to post-mortem examination

Reachable by walking: inappropriate integration of near and far space may lead to distance errors

Our experimental results show that infants while learning to walk intend to reach for unreachable objects. These distance errors may result from inappropriate integration of reaching and locomotor actions, attention control and near/far visual space. Infants during their first months are fairly immobile, their attention and actions are constrained to near (reachable) space. Walking, in contrast, lures attention to distal displays and provides the information to disambiguate far space. In this paper, we make use of a reward-mediated learning to mimic the development of absolute distance perception. The results obtained with the NAO robot support further our hypothesis that the representation of near space changes after the onset of walking, which may cause the occurrence of distance errors

Reaching for the Unreachable: Reorganization of Reaching with Walking

Previous research suggests that reaching and walking behaviors may be linked developmentally as reaching changes at the onset of walking. Here we report new evidence on an apparent loss of the distinction between the reachable and nonreachable distances as children start walking. The experiment compared non-walkers, walkers with help, and independent walkers in a reaching task to targets at varying distances. Reaching attempts, contact, leaning, and communication behaviors were recorded. Most of the children reached for the unreachable objects the first time it was presented. Non-walkers, however, reached less on the subsequent trials showing clear adjustment of their reaching decisions with the failures. On the contrary, walkers consistently attempted reaches to targets at unreachable distances. We suggest that these reaching errors may result from inappropriate integration of reaching and locomotor actions, attention control and near/far visual space. We propose a rewardmediated model implemented on a NAO humanoid robot that replicates the main results from our study showing an increase in reaching attempts to nonreachable distances after the onset of walking

Integration of Static and Self-motion-Based Depth Cues for Efficient Reaching and Locomotor Actions

The common approach to estimate the distance of an object in computer vision and robotics is to use stereo vision. Stereopsis, however, provides good estimates only within near space and thus is more suitable for reaching actions. In order to successfully plan and execute an action in far space, other depth cues must be taken into account. Self-body movements, such as head and eye movements or locomotion can provide rich information of depth. This paper proposes a model for integration of static and self-motion-based depth cues for a humanoid robot. Our results show that self-motion-based visual cues improve the accuracy of distance perception and combined with other depth cues provide the robot with a robust distance estimator suitable for both reaching and walking actions

Reachable by walking: inappropriate integration of near and far space may lead to distance errors

Our experimental results show that infants while learning to walk intend to reach for unreachable objects. These distance errors may result from inappropriate integration of reaching and locomotor actions, attention control and near/far visual space. Infants during their first months are fairly immobile, their attention and actions are constrained to near (reachable) space. Walking, in contrast, lures attention to distal displays and provides the information to disambiguate far space. In this paper, we make use of a reward-mediated learning to mimic the development of absolute distance perception. The results obtained with the NAO robot support further our hypothesis that the representation of near space changes after the onset of walking, which may cause the occurrence of distance errors

Retinoid-Binding Proteins: Similar Protein Architectures Bind Similar Ligands via Completely Different Ways

Background: Retinoids are a class of compounds that are chemically related to vitamin A, which is an essential nutrient that plays a key role in vision, cell growth and differentiation. In vivo, retinoids must bind with specific proteins to perform their necessary functions. Plasma retinol-binding protein (RBP) and epididymal retinoic acid binding protein (ERABP) carry retinoids in bodily fluids, while cellular retinol-binding proteins (CRBPs) and cellular retinoic acid-binding proteins (CRABPs) carry retinoids within cells. Interestingly, although all of these transport proteins possess similar structures, the modes of binding for the different retinoid ligands with their carrier proteins are different. Methodology/Principal Findings: In this work, we analyzed the various retinoid transport mechanisms using structure and sequence comparisons, binding site analyses and molecular dynamics simulations. Our results show that in the same family of proteins and subcellular location, the orientation of a retinoid molecule within a binding protein is same, whereas when different families of proteins are considered, the orientation of the bound retinoid is completely different. In addition, none of the amino acid residues involved in ligand binding is conserved between the transport proteins. However, for each specific binding protein, the amino acids involved in the ligand binding are conserved. The results of this study allow us to propose a possible transport model for retinoids. Conclusions/Significance: Our results reveal the differences in the binding modes between the different retinoid-bindin