The effect of spaceflight on the otolith-mediated ocular counter-roll

The otoliths of the vestibular system are seen as the primary gravitational sensors and are responsible for a compensatory eye torsion called the ocular counter-roll (OCR). The OCR ensures gaze stabilization and is sensitive to a lateral head roll with respect to gravity and the Gravito-Inertial Acceleration (GIA) vector during e.g., centrifugation. This otolith-mediated reflex will make sure you will still be able to maintain gaze stabilization and postural stability when making sharp turns during locomotion. To measure the effect of prolonged spaceflight on the otoliths, we measured the OCR induced by off-axis centrifugation in a group of 27 cosmonauts before and after their 6-month space mission to the International Space Station (ISS). We observed a significant decrease in OCR early post-flight, with first- time flyers being more strongly affected compared to frequent or experienced flyers. Our results strongly suggest that experienced space crew have acquired the ability to adapt faster after G-transitions and should therefore be sent for more challenging space missions, e.g., Moon or Mars, because they are noticeably less affected by microgravity regarding their vestibular system

Prolonged microgravity induces reversible and persistent changes on human cerebral connectivity

peer reviewedThe prospect of continued manned space missions warrants an in-depth understanding of how prolonged microgravity affects the human brain. Functional MRI can pinpoint changes reflecting adaptive neuroplasticity across time. We acquired resting-state functional MRI data in 15 cosmonauts before, shortly after, and seven months after spaceflight as a follow-up to assess global connectivity changes over time. Our results show persisting connectivity decreases in posterior cingulate cortex and thalamus. and persisting increases in the right angular gyrus. Connectivity in the bilateral insular cortex decreased after spaceflight, which reversed at follow-up. No significant connectivity changes across eight months were found in a matched control group. Overall, we show that altered gravitational environments influence functional connectivity longitudinally in multimodal brain hubs, reflecting adaptations to unfamiliar and conflicting sensory input in microgravity. These results provide new insights into brain functional modifications occurring during spaceflight, and their further development when back on Earth

The effect of prolonged spaceflight on cerebrospinal fluid and perivascular spaces of astronauts and cosmonauts

peer reviewedLong-duration spaceflight induces changes to the brain and cerebrospinal fluid compartments and visual acuity problems known as spaceflight-associated neuro-ocular syndrome (SANS). The clinical relevance of these changes and whether they equally affect crews of different space agencies remain unknown. We used MRI to analyze the alterations occurring in the perivascular spaces (PVS) in NASA and European Space Agency astronauts and Roscosmos cosmonauts after a 6-mo spaceflight on the International Space Station (ISS). We found increased volume of basal ganglia PVS and white matter PVS (WM-PVS) after spaceflight, which was more prominent in the NASA crew than the Roscosmos crew. Moreover, both crews demonstrated a similar degree of lateral ventricle enlargement and decreased subarachnoid space at the vertex, which was correlated with WM-PVS enlargement. As all crews experienced the same environment aboard the ISS, the differences in WM-PVS enlargement may have been due to, among other factors, differences in the use of countermeasures and high-resistive exercise regimes, which can influence brain fluid redistribution. Moreover, NASA astronauts who developed SANS had greater pre- and postflight WM-PVS volumes than those unaffected. These results provide evidence for a potential link between WM-PVS fluid and SANS. Copyright © 2022 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY)

Bio-ecological processes in schools: The role of teachers, peers, and genes in children's and adolescents' psychological and academic development

Throughout late childhood and adolescence, there is a general increase in adjustment problems, including an increase in psychosocial problems, such as externalizing behavior, and an increase in academic problems, such as declining levels of behavioral school engagement. The present doctoral dissertation offers a comprehensive framework for understanding the development of externalizing behavior and behavioral engagement, guided by the bio-ecological model of human development (Bronfenbrenner & Morris, 2006), which explains individual differences in development in terms of both environmental and biological influences and interactions between them. We focused on how the affective quality of teacher-student relationships, peer likeability and peer popularity impact children’s and adolescents’ behavioral school engagement and externalizing behavior. In addition, we revealed the bi-directional effects and transactional processes between teacher-student relationships and peer relationships in elementary school, and between teacher-student relationships and adolescent adjustment problems in secondary school. Based on the biological side of Bronfenbrenner’s model – which suggests that biologically-based factors may join with environmental factors to shape development – we investigated whether dopaminergic genes moderate the effect of teacher-student relationships on adolescents’ adjustment problems. Four empirical studies are included. The first two are based on a longitudinal project which includes 586 children from Grade 4, followed for three years (Sample 1). The second two are based on the longitudinal project Studying the Transition to Adolescence: Testing Genes, Interactions, and Environments (STRATEGIES) which includes 1116 adolescents from Grade 7 to 9, followed for three years (Sample 2). Several self-reported, parent-reported, and peer-reported measures were used to assess our research variables. To analyse the data, we used parallel latent growth curve analyses, cross-lagged analyses, multigroup analyses, and hierarchical regression analyses in the framework of structural equation modelling (SEM) using Mplus version 6 (Muthén & Muthén, 1998-2010). In the first study, we examined the reciprocal associations among teacher-student and peer relationships in late elementary school (Sample 1) and found that higher peer likeability predicted more teacher-student support, which in turn predicted higher peer likeability, beyond changes in children’s prosocial behavior. Higher peer popularity predicted more teacher-student conflict (driven by children’s aggressive behavior), which, in turn and in itself, predicted higher perceived popularity. The second study investigated whether teacher-student and peer relationships may buffer or exacerbate the normative declines in behavioral engagement in late elementary school (Sample 1)and showed that high initial and increasing levels of teacher-student support and high initial levels of peer likeability independently reduce the normative declines in children’s behavioral engagement. Children who were perceived as more popular in Grade 5 were less engaged in school in Grade 6. The third study aimed to test whether adolescents’ genotype for the dopamine transporter (DAT1) or receptor (DRD4) moderates the effect of teacher-student relationship quality on adolescents’ rule-breaking behavior and behavioral engagement (Sample 2). It seems that DAT1-10R homozygotes were more affected by the negative effect of lower teacher-student affiliation on behavioral engagement and that DRD4 non-long carriers were more affected by the adverse effect of teacher-student dissatisfaction on rule-breaking behavior. In the fourth study (Sample 2), we examined bidirectional relations between teacher-student relationship quality and adolescent rule-breaking behavior and behavioral engagement throughout secondary school. In addition, we investigated whether the effects of teacher-student relationship quality on subsequent adolescent behavior were moderated by a biologically informed polygenetic score (BIMPS) for dopamine signalling. We found that adolescents who displayed more rule-breaking behavior and less behavioral engagement experienced increased subsequent dissatisfaction with their teachers, which in turn further increased their adjustment problems. Also, adolescents with more adjustment problems experienced decreased subsequent affiliation with their teachers. The other way around, adolescents’ behavioral engagement also benefitted from positive relationships with teachers. In addition, adolescents who had a BIMPS score coding for moderate levels of dopamine signalling (instead of high or low signalling) were most affected in their behavioral engagement when they experienced dissatisfaction with their teachers.status: publishe

Geometric relations between rigid bodies (part 2): From Semantics to Software

Rigid bodies are essential primitives in the modelling of robotic devices, tasks, and percep- tion. Basic geometric relations between rigid bodies in- clude relative position, orientation, pose, linear veloc- ity, angular velocity, twist, force, torque, and wrench. In Part 1, we explicitly stated the semantics of all coordinate-invariant properties and operations, and, more importantly, all the choices that are made in co- ordinate representations of these geometric relations. This resulted in a set of concrete suggestions for stan- dardizing terminology and notation. In this tutorial, we show how the proposed semantics allow us to write fully unambiguous software interfaces, including auto- matic checks for semantic correctness of all geometric operations on rigid-body coordinate representations.status: publishe

Floral ontogeny in the Plumbaginaceae

A scanning electron microscopic study of the floral ontogeny of seven species of the Plumbaginaceae (representing five genera of the Armerioideae and two of the Plumbagoideae) is presented. The early ontogenetic stages in all species examined are sufficiently similar to propose the following familial description. The five sepal primordia are initiated simultaneously or spirally. These soon reach continuity and develop into the synsepalous calyx. Meanwhile, five common stamen-petal primordia that alternate with the sepal primordia are initiated simultaneously on the flattened apex. Soon, two distinct growth-centres can be observed on each of these primordia: a petal primordium at the abaxial side and a stamen primordium on the top. After inception of the common primordia, five gynoecial primordia alternating with the common primordia are initiated simultaneously on the corners of the apex that has become pentagonal. These primordia soon reach continuity and develop into the superior unilocular gynoecium. Continuity between the gynoecial primordia is reached earlier in the Plumbagoideae than in the Armerioideae. In the centre of the ovary a primordium arises that develops into the single basal circinotropous bitegmic ovule. The floral nectaries are associated with the androecium.status: publishe