Geographic range extension of Speke's Hinge-back Tortoise Kinixys spekii Gray, 1863

Kinixys spekii has a wide distribution range across sub-Saharan Africa, having been reported from Angola, Botswana, Burundi, the Democratic Republic of the Congo, eSwatini, Kenya, Malawi, Mozambique, Namibia, South Africa, Tanzania, Zambia, and Zimbabwe. Kinixys spekii inhabits savannah and dry bushveld habitats and was previously considered an inland species. However, recent records suggest a more extensive geographical distribution. Here, we provide genetically verifed records for Angola, South Africa, and Mozambique, and discuss reliable sightings for Rwanda. These new records extend the range signifcantly to the east and west, and provide evidence for the occurrence of this species along the coast of the Indian Ocean in South Africa and Mozambique.© 2019 Ihlow et al. This is an open access article distributed under the terms of the Creative Commons Attribution License [Attribution 4.0 International (CC BY 4.0): https://creativecommons.org/licenses/by/4.0/], which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The official and authorized publication credit sources, which will be duly enforced, are as follows: offcial journal title Amphibian & Reptile Conservation; official journal website: amphibian-reptile-conservation.org

Distinct tissue niches direct lung immunopathology via CCL18 and CCL21 in severe COVID-19

Prolonged lung pathology has been associated with COVID-19, yet the cellular and molecular mechanisms behind this chronic inflammatory disease are poorly understood. In this study, we combine advanced imaging and spatial transcriptomics to shed light on the local immune response in severe COVID-19. We show that activated adventitial niches are crucial microenvironments contributing to the orchestration of prolonged lung immunopathology. Up-regulation of the chemokines CCL21 and CCL18 associates to endothelial-to-mesenchymal transition and tissue fibrosis within these niches. CCL21 over-expression additionally links to the local accumulation of T cells expressing the cognate receptor CCR7. These T cells are imprinted with an exhausted phenotype and form lymphoid aggregates that can organize in ectopic lymphoid structures. Our work proposes immune-stromal interaction mechanisms promoting a self-sustained and non-resolving local immune response that extends beyond active viral infection and perpetuates tissue remodeling

Global realized niche divergence in the African clawed frog Xenopus laevis

Although of crucial importance for invasion biology and impact assessments of climate change, it remains widely unknown how species cope with and adapt to environmental conditions beyond their currently realized climatic niches (i.e., those climatic conditions existing populations are exposed to). The African clawed frog Xenopus laevis, native to southern Africa, has established numerous invasive populations on multiple continents making it a pertinent model organism to study environmental niche dynamics. In this study, we assess whether the realized niches of the invasive populations in Europe, South, and North America represent subsets of the species’ realized niche in its native distributional range or if niche shifts are traceable. If shifts are traceable, we ask whether the realized niches of invasive populations still contain signatures of the niche of source populations what could indicate local adaptations. Univariate comparisons among bioclimatic conditions at native and invaded ranges revealed the invasive populations to be nested within the variable range of the native population. However, at the same time, invasive populations are well differentiated in multidimensional niche space as quantified via n-dimensional hypervolumes. The most deviant invasive population are those from Europe. Our results suggest varying degrees of realized niche shifts, which are mainly driven by temperature related variables. The crosswise projection of the hypervolumes that were trained in invaded ranges revealed the south-western Cape region as likely area of origin for all invasive populations, which is largely congruent with DNA sequence data and suggests a gradual exploration of novel climate space in invasive populations

Attaining low uncertainties in measurements with RF signal generators and analyzers

In this paper, practical investigations of level accuracy and uncertainties using a Rohde & Schwarz signal generator (R&S SMB-B140) and spectrum analyzer (R&S FSV40) are performed up to 30GHz. We show that it is possible to measure frequency responses of DUTs with uncertainties below ±0.05dB up to 30 GHz instead of ±0.5...1.5dB using auto settings, standard setup, or relying on datasheets. The level linearity of instruments with integrated step attenuators is shown to be improved to ±0.03dB instead of ±0.3...1dB by using a special “hybrid” procedure. Furthermore, it is shown how computer aided measurements procedures should be programmed with these instruments to attain low deviations between measurements

Competition and feeding ecology in two sympatric Xenopus species (Anura: Pipidae)

CITATION: Vogt, S., et al. 2017. Competition and feeding ecology in two sympatric Xenopus species (Anura: Pipidae). PeerJ, 5:e3130, doi:10.7717/peerj.3130/table-1.The original publication is available at https://peerj.comPublication of this article was funded by the Stellenbosch University Open Access Fund.The widespread African clawed frog (Xenopus laevis) occurs in sympatry with the IUCN Endangered Cape platanna (Xenopus gilli) throughout its entire range in the south-western Cape, South Africa. In order to investigate aspects of the interspecific competition between populations of X. laevis and X. gilli, an assessment of their niche differentiation was conducted through a comprehensive study on food composition and trophic niche structure at two study sites: the Cape of Good Hope (CoGH) and Kleinmond. A total of 399 stomach contents of X. laevis (n = 183) and X. gilli (n = 216) were obtained together with samples of available prey to determine food preferences using the Electivity index (E*), the Simpson’s index of diversity (1 − D), the Shannon index (H′), and the Pianka index (Ojk). Xenopus gilli diet was more diverse than X. laevis, particularly in Kleimond where the Shannon index was nearly double. Both species were found to consume large amounts of tadpoles belonging to different amphibian species, including congeners, with an overall higher incidence of anurophagy than previously recorded. However, X. laevis also feeds on adult X. gilli, thus representing a direct threat for the latter. While trophic niche overlap was 0.5 for the CoGH, it was almost 1 in Kleinmond, suggesting both species utilise highly congruent trophic niches. Further, subdividing the dataset into three size classes revealed overlap to be higher in small frogs in both study sites. Our study underlines the importance of actively controlling X. laevis at sites with X. gilli in order to limit competition and predation, which is vital for conservation of the south-western Cape endemic.https://peerj.com/articles/3130/Publisher's versio

Implementation of sparse signal recovery on FPGA for ultrasonic NDT

For several use cases of complex processing algorithms on ultrasound NDT data, it is mandatory to ensure real-time signal processing speed. This can be achieved by using e.g. a field programmable gate array (FPGA). Sparse signal recovery (SSR) and compressed sensing (CS) methods are used for superior reconstruction of flaws from compressed measurement data. SSR and CS are currently a hot research topic in various fields of application. However, they are not yet implemented for ultrasound NDT in a real-time manner