4 research outputs found
Internally displaced persons and COVID-19: a wake-up call for and African solutions to African problems – the case of Zimbabwe
No full textIn this paper we engage with the situation of internally displaced persons (IDPs) residing in two informal settlements in Zimbabwe, within the context of the COVID-19 pandemic. We draw on an ongoing collaborative, interdisciplinary and impact-oriented project that seeks to help IDPs to be more prepared to protect themselves from the COVID-19 pandemic. We start by providing an analysis of the existing COVID-19 preventative messages and their applicability to the IDPs situation, and further argue for the need to adopt Transformative Public Health Education (TPHE), to allow co-creation and co-production with IDPs in order to produce messages and interventions that suit their lived realities. We then move on to show the importance of leveraging local low cost COVID-19 solutions, drawing on the example of the innovations that the project adapted in order to meet the needs of the IDPs residing in the two informal settlements
Granular lightweight fill composed of sand and tire scrap
No full textA granular geomaterial, known as sand-tire lightweight fill, was proposed by blending sand with disposed tire scrap in proportions. The geomaterial can be used as alternative backfill in many infrastructure works, where less overburdens and lateral loads are expected. The reuse of tire scraps may not only address growing environmental and economic concerns, but also help solve geotechnical problems associated with low soil shear strength. In this study, an experimental testing program was undertaken with the goal of evaluating the compression and shear behavior of the materials. Three tests were implemented, i.e., 1-D compression tests, direct shear tests and consolidated drained triaxial compression tests. A compression strain-load model was proposed to describe its compression behavior. Rebound-reload tests revealed that materials' plastic deformation was associated with the mixing ratios. The tire scrap content was found to influence the stress-strain and volumetric strain behavior of the mixtures. Mixtures underwent shear contraction during shearing processes, which is different from the shear dilation of compact sands. Effects of mixing ratios and stress conditions on shear deformation behaviors were also discussed.An Deng and Jin-Rong Fenghttp://ascelibrary.org/doi/abs/10.1061/41041%28348%291
Interspecific chromosomal divergences in the genus Characidium (Teleostei: Characiformes: Crenuchidae)
No full textKaryotypes of seven fish species of the genus Characidium, three of them studied for the first time, were characterized using conventional cytogenetic techniques (Giemsa staining, Ag-NOR, and C-banding). All species presented a diploid number of 2n=50, with only metacentric and submetacentric chromosomes, as observed in all Characidium species studied. In two species cells with one to three B chromosomes were observed. All species analyzed have a single NOR-bearing chromosome pair with morphological differences among them. Characidium cf. zebra shows heterochromatic blocks restricted to the pericentromeric regions of all chromosomes denoting the absence of a sex chromosome system. On the other hand, the species Characidium lanei, C. pterostictum, C. lauroi, C. oiticicai, C. schubarti, and Characidium sp., besides presenting pericentromeric heterochromatic blocks, exhibited large interstitial and/or terminal heterochromatic blocks, and a ZZ/ZW sex chromosome system. The constitutive heterochromatin seems to play a relevant role in the chromosome differentiation process of the studied species, mainly in relation to the sex chromosomes. The geographical isolation of the rivers in which the species were sampled, associated with their way of life restricted to headwaters environments, may have favored the process of fixation of different karyotypes found in each of the analyzed species
Caudate Nucleus Volume Mediates the Link between Cardiorespiratory Fitness and Cognitive Flexibility in Older Adults.
No full textThe basal ganglia play a central role in regulating the response selection abilities that are critical for mental flexibility. In neocortical areas, higher cardiorespiratory fitness levels are associated with increased gray matter volume, and these volumetric differences mediate enhanced cognitive performance in a variety of tasks. Here we examine whether cardiorespiratory fitness correlates with the volume of the subcortical nuclei that make up the basal ganglia and whether this relationship predicts cognitive flexibility in older adults. Structural MRI was used to determine the volume of the basal ganglia nuclei in a group of older, neurologically healthy individuals (mean age 66 years, N = 179). Measures of cardiorespiratory fitness (VO(2max)), cognitive flexibility (task switching), and attentional control (flanker task) were also collected. Higher fitness levels were correlated with higher accuracy rates in the Task Switching paradigm. In addition, the volume of the caudate nucleus, putamen, and globus pallidus positively correlated with Task Switching accuracy. Nested regression modeling revealed that caudate nucleus volume was a significant mediator of the relationship between cardiorespiratory fitness, and task switching performance. These findings indicate that higher cardiorespiratory fitness predicts better cognitive flexibility in older adults through greater grey matter volume in the dorsal striatum.</p
