Neonatal White Matter Maturation Is Associated With Infant Language Development

Background: While neonates have no sophisticated language skills, the neural basis for acquiring this function is assumed to already be present at birth. Receptive language is measurable by 6 months of age and meaningful speech production by 10-18 months of age. Fiber tracts supporting language processing include the corpus callosum (CC), which plays a key role in the hemispheric lateralization of language; the left arcuate fasciculus (AF), which is associated with syntactic processing; and the right AF, which plays a role in prosody and semantics. We examined if neonatal maturation of these fiber tracts is associated with receptive language development at 12 months of age. Methods: Diffusion-weighted imaging (DWI) was performed in 86 infants at 26.6 ± 12.2 days post-birth. Receptive language was assessed via the MacArthur-Bates Communicative Development Inventory at 12 months of age. Tract-based fractional anisotropy (FA) was determined using the NA-MIC atlas-based fiber analysis toolkit. Associations between neonatal regional FA, adjusted for gestational age at birth and age at scan, and language development at 12 months of age were tested using ANOVA models. Results: After multiple comparisons correction, higher neonatal FA was positively associated with receptive language at 12 months of age within the genu (p < 0.001), rostrum (p < 0.001), and tapetum (p < 0.001) of the CC and the left fronto-parietal AF (p = 0.008). No significant clusters were found in the right AF. Conclusion: Microstructural development of the CC and the AF in the newborn is associated with receptive language at 12 months of age, demonstrating that interindividual variation in white matter microstructure is relevant for later language development, and indicating that the neural foundation for language processing is laid well ahead of the majority of language acquisition. This suggests that some origins of impaired language development may lie in the intrauterine and potentially neonatal period of life. Understanding how interindividual differences in neonatal brain maturity relate to the acquisition of function, particularly during early development when the brain is in an unparalleled window of plasticity, is key to identifying opportunities for harnessing neuroplasticity in health and disease

Strand directionality affects cation binding and movement within tetramolecular G-quadruplexes

Nuclear magnetic resonance study of G-quadruplex structures formed by d(TG3T) and its modified analogs containing a 50-50 or 30-30 inversion of polarity sites, namely d(30TG50-50G2T30), d(30T50- 50G3T30) and d(50TG30-30G2T5’) demonstrates formation of G-quadruplex structures with tetrameric topology and distinct cation-binding preferences. All oligonucleotides are able to form quadruplex structures with two binding sites, although the modified oligonucleotides also form, in variable amounts, quadruplex structures with only one bound cation. The inter-quartet cavities at the inversion of polarity sites bind ammonium ions less tightly than a naturally occurring 50-30 backbone. Exchange of 15NH+ 4 ions between G-quadruplex and bulk solution is faster at the 30-end in comparison to the 50-end. In addition to strand directionality, cation movement is influenced by formation of an all-syn G-quartet. Formation of such quartet has been observed also for the parent d(TG3T) that besides the canonical quadruplex with only all-anti G-quartets, forms a tetramolecular parallel quadruplex containing one all-syn G-quartet, never observed before in unmodified quadruplex structures

Optimization of curing cycle in carbon fiber-reinforced laminates: Void distribution and mechanical properties

A strategy is presented to optimize out-of-autoclave processing of quasi-isotropic carbon fiber-reinforced laminates. Square panels of 4.6 mm nominal thickness with very low porosity ð6 0:2%Þ were manufactured by compression molding at low pressure (0.2 MPa) by careful design of the temperature cycle to maximize the processing window. The mechanisms of void migration during processing were ascertained by means of X-ray microtomography and the effect of ply clustering on porosity and on void shape was explained. Finally, the effect of porosity and ply clustering on the compressive strength before and after impact was studied