We report the results of a proton NMR investigation of a new class of thermotropic nematic liquid crystalline polyesters with mesogenic elements and flexible spacers in the main chain. The NMR line shapes and line widths as a function of temperature are used to derive information on the molecular organization and dynamics in the solid and nematic phases of samples differing by their molecular weight and spacer length. Homogeneous orientation of the macromolecules in the nematic phase was observed for a sample of a¡ 4000 in the magnetic field of 11.7 kG used in the NMR experiment. The nematic order parameter of this sample was found to vary between 0.69 at the nematic-isotropic and 0.84 at the solid-nematic transition temperature, thus taking unusually high values. From a detailed analysis of the corresponding NMR spectrum we show that the flexible spacers align in the magnetic field with a degree of order comparable to that of the mesogenic elements, which implies that the macromolecules take, on the average, a rather extended conformation.

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Clinical populations with basal ganglia pathologies may present with language production impairments, which are often described in combination with comprehension measures or attributed to motor, memory, or processing-speed problems. In this systematic review and meta-analysis, we studied word production in four (vascular and non-vascular) pathologies of the basal ganglia: stroke affecting the basal ganglia, small vessel disease, Parkinson's disease, and Huntington's disease. We compared scores of these clinical populations with those of matched cognitively unimpaired adults on four well-established production tasks, namely picture naming, category fluency, letter fluency, and past-tense verb inflection. We conducted a systematic search in PubMed and PsycINFO with terms for basal ganglia structures, basal ganglia disorders and language production tasks. A total of 114 studies were included, containing results for one or more of the tasks of interest. For each pathology and task combination, effect sizes (Hedges' g) were extracted comparing patient versus control groups. For all four populations, performance was consistently worse than that of cognitively unimpaired adults across the four language production tasks (p-values < 0.010). Given that performance in picture naming and verb inflection across all pathologies was quantified in terms of accuracy, our results suggest that production impairments cannot be fully explained by motor or processing-speed deficits. Our review shows that while language production difficulties in these clinical populations are not negligible, more evidence is necessary to determine the exact mechanism that leads to these deficits and whether this mechanism is the same across different pathologies.