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Fig. 57 in A revision of the Chilodontidae (Gastropoda: Vetigastropoda: Seguenzioidea) of southern Africa and the south-western Indian Ocean

Fig. 57. Distribution of Perrinia konos. Each triangle represents one or more records.

Fig. 20 in A revision of the Chilodontidae (Gastropoda: Vetigastropoda: Seguenzioidea) of southern Africa and the south-western Indian Ocean

Fig. 20. Distribution of Ascetostoma providentiae. Each triangle represents one or more records.

Fig. 44 in A revision of the Chilodontidae (Gastropoda: Vetigastropoda: Seguenzioidea) of southern Africa and the south-western Indian Ocean

Fig. 44. Distribution of Vaceuchelus gemmula. Each triangle represents one or more records.

Fig. 34 in A revision of the Chilodontidae (Gastropoda: Vetigastropoda: Seguenzioidea) of southern Africa and the south-western Indian Ocean

Fig. 34. Distribution of Herpetopoma helix. Each triangle represents one or more records.

opencc-by-4.0Jun 2012View details →

Fig. 23 in A new species of Diopsis L. (Diptera: Diopsidae) from South Africa and Swaziland, and brief review of African species with a large apical wing spot

Fig. 23. Diopsis stuckenbergi sp. n., eye span plotted against body length.

opencc-by-4.0Jun 2012View details →

Fig. 16 in Five new species of scuttle fly (Diptera: Phoridae) from southern Africa

Fig. 16. Phalacrotophora occidentata Disney, ♂, left face of hypopygium. Scale bar = 0.1 mm.

opencc-by-4.0Jun 2012View details →

Fig. 5 in A new species of Diopsis L. (Diptera: Diopsidae) from South Africa and Swaziland, and brief review of African species with a large apical wing spot

Fig. 5. Diopsis eisentrauti, eye span plotted against body length.

opencc-by-4.0Dec 2004View details →

Fig. 24 in Four new narrow-range endemic species of Gulella from Eastern Cape, South Africa (Mollusca: Pulmonata: Streptaxidae)

Fig. 24. Map of northern Eastern Cape showing distribution of new species.

opencc-by-4.0Dec 2011View details →

Fig. 1 in Four new species of Turbonilla (Gastropoda, Pyramidellimorpha, Turbonillidae) from the Gulf of Guinea, West Africa

Fig. 1. Study area and sampling sites.

opencc-by-4.0Dec 2009View details →

Fig. 17 in The Tardigrada of southern Africa, with the description of Minibiotus harrylewisi, a new species from KwaZulu-Natal, South Africa (Eutardigrada: Macrobiotidae)

Fig. 17. Egg of Minibiotus harrylewisi sp. n., KwaZulu-Natal, South Africa. Scale bar = 20 µm.

opencc-by-4.0Dec 2013View details →

Fig. 4 in Rediscovering the old from new: two curious species of Coenosia Meigen (Diptera: Muscidae) from South Africa

Fig. 4. First pair of orbital setae of Coenosia macrotriseta sp. n., ♂: (A) apex, (B) base.

openFeb 2023View details →

56th CIRP Conference on Manufacturing Systems, CIRP CMS '23, South Africa - Enhancing SLM Stainless Steel: Model-Based Parameter Optimization

SLM (selective laser melting) has faced challenges in ensuring consistent mechanical properties for various geometries in the past. However, the authors have developed a system that solves this issue by calculating the optimal process parameters for each scan vector on each layer. This approach ensures consistent melt pool geometry, derived from the most robust in conduction welding mode. The results from the single melt-line experiments and the presented thermal conduction solver demonstrate the effectiveness of this approach in achieving a stable melt pool geometry in stainless steel (1.4404 or 316L). Furthermore, a rigorous testing regimen has been implemented to evaluate the system under different changing boundary conditions, to further demonstrate its usefulness. By utilizing this system, manufacturers will achieve consistent and high-quality mechanical properties for small lot sizes, including spare and obsolescent parts.

opencc-zeroMay 2023View details →

Obuasi case study data: Performance of neutral SNP barcodes to determine genetic diversity and structure of Plasmodium falciparum in Africa

A small number of informative biallelic single nucleotide polymorphisms (SNPs) have been proposed to be an economical method to fast-track the genotyping and relatedness analysis of Plasmodium falciparum in malaria-endemic areas. Whilst used successfully in low-transmission areas where infections are monoclonal and highly related, we present the first study to evaluate the performance of these 24- and 96-SNP molecular barcodes in African countries characterised by moderate-to-high transmission. Using haplotypes generated from the MalariaGEN P. falciparum Community Project version 6 database, 52.3% of infections were multiclonal, generating high frequencies of mixed-allele calls (MACs) per isolate. Both multiclonality and low heterozygosity of SNPs impeded haplotype construction for analyses of relatedness. Although fewer SNPs provided usable data, these SNP barcodes weakly identified genetic differentiation across large geographic distances. However, both minor and major alleles' frequencies were temporally unstable. We conclude that these standardised SNP barcodes are vulnerable to ascertainment bias. While large numbers of SNPs acquired by whole-genome sequencing and computational methods to construct haplotypes present a way forward, these approaches may not be practical or cost-effective for surveillance on large scales in malaria-endemic areas.

opencc-by-4.0May 2023View details →

75-kyr paired mean summer temperature (MST) and moisture balance (BIT-index) data for eastern equatorial Africa based on GDGT distributions in the DeepCHALLA sediment sequence

The DeepCHALLA (DCH) GDGT-based climate proxy data series consist of paired measurements on 373 discrete 2-cm-thick sediment samples, represented by their DCH event-free depth in meter (mefd). Section depth center refers to the distance (in cm) of the sample’s center from the top of the individual core section as represented by its DCH core code. Sediment age is based on the age model as presented in Fig. 2 in Baxter et al. (2023). Mean Summer Temperature (MST) was calculated from the distribution of sedimentary brGDGTs according to Pearson et al. (2011) and rescaled using an ensemble reconstruction for eastern Africa covering the last 25 ka (Extended Data Fig. 4 in Baxter et al., 2023). The branched versus isoprenoid tetraether (BIT) index of sedimentary brGDGTs from Lake Chala, reflecting lake water-balance variation, was calculated according to Hopmans et al. (2004).

opencc-zeroJun 2023View details →

Spring arrival of the common cuckoo at breeding grounds is strongly determined by environmental conditions in tropical Africa

Failure to adapt migration timing to changes in environmental conditions along migration routes and at breeding locations can result in mismatches across trophic levels, as occurs between the brood parasitic common cuckoo Cuculus canorus and its hosts. Using satellite tracking data from 87 male cuckoos across 11 years, we evaluate why the cuckoo has not advanced its arrival to the UK. Across years, breeding ground arrival was primarily determined by timing of departure from stopover in West Africa before northward crossing of the Sahara. Together with high population synchrony and low apparent endogenous control of this event, this suggests that a seasonal ecological constraint operating here limits overall variation in breeding grounds arrival, although this event was itself influenced by carry-over from timing of arrival into tropical Africa. Between-year variation within individuals was, in contrast, mostly determined by northward migration through Europe, likely due to weather conditions. We find evidence of increased mortality risk for a) early birds following migration periods positively impacting breeding grounds arrival, and b) late birds, possibly suffering energy limitation, after departure from the breeding grounds. These results help identify areas where demands of responding to global change can potentially be alleviated by improving stopover quality.

opencc-zeroJun 2023View details →

Africa's ecosystems exhibit a tradeoff between resistance and stability following disturbances

Environmental disturbances may prevent ecosystems from consistently performing their critical ecological functions. Two important properties of ecosystems are their resistance and stability, which respectively reflect their capacities to withstand and recover from disturbance events (e.g., droughts, wildfires, pests, etc.). Theory suggests that resistant and stable ecosystems possess opposing characteristics, but this has seldom been established across diverse ecosystem attributes or broad spatial scales. Here, we compare the resistance and stability of >1,000 protected area ecosystems in Africa to disturbance-induced losses in primary productivity from 2000-2019. We quantitatively evaluated each ecosystem such that following disturbances, an ecosystem is more resistant if it experiences lower-magnitude losses in productivity, and more stable if it returns more rapidly to pre-disturbance productivity levels. To compare the characteristics of resistant versus stable ecosystems, we optimized random forest models that use ecosystem attributes (representing their climatic and environmental conditions, plant and faunal biodiversity, and exposure to human impacts) to predict their resistance and, separately, stability values. We visualized each attribute's relationship with resistance and stability after accounting for all other attributes in the model framework. Ecosystems that are more resistant to disturbances are less stable, and vice versa. The ecosystem attributes with the most predictive power in our models all exhibit contrasting relationships with resistance versus stability. Notably, highly resistant ecosystems are generally more arid and exhibit high habitat heterogeneity and mammalian biodiversity, while highly stable ecosystems are the opposite. We discuss the underlying mechanisms through which these attributes engender resistance or, conversely, stability. Our findings suggest that resistance and stability are fundamentally opposing phenomena. A balance between the two must be struck if ecosystems are to maintain their identity, structure, and function in the face of environmental change.

opencc-zeroJun 2023View details →

Data from: The fate of nitrogen during agricultural intensification in East Africa: nitrogen budgets in contrasting agroecosystems

The intensification of agricultural systems in sub-Saharan Africa (SSA) is necessary to reduce poverty and improve food security but requires increased nutrient applications to smallholder systems. To avoid the negative consequences of intensification that result from many large-scale agricultural systems (e.g., eutrophication), we must better understand how diverse soil systems in SSA will respond to increased fertilizer applications. We tracked nitrogen (N) inputs and outputs in fertilizer trials at two maize (Zea mays)-agroecological regions of contrasting soil type. We measured maize biomass, grain yields, N leaching, and N gaseous losses from a clayey soil in Yala, Kenya, and a sandy soil in Tumbi, Tanzania, with application rates of 0, 50, 75, 100, 150, and 200 kg N ha-1 yr‑1 over multiple years. Using measurements of NO, N2O, NO3-, biomass N, and an 15N enrichment experiment, we show that N budgets in Yala were nearly always negative, meaning more N was exported in yields or lost from the system than was added in fertilizer. In Tumbi, however, N budgets were negative at lower fertilizer levels (0 and 50 kg N ha-1), but positive at higher fertilizer levels (75 and 200 kg N ha-1). At both sites, most of the N was lost through maize biomass/grain removal and N leaching (over 96% of total losses). Gas losses were a minor component of N budgets. These results highlight the importance of tailoring fertilizer recommendations to a farm's specific soil and climatic conditions. However, on these two contrasting sites, fertilizer additions at or below 50 kg N ha-1 do not lead to major losses of N (via gaseous or leaching) and may be recommended at a range of sites across SSA soils in maize agroecosystems.

opencc-by-nc-4.0Jul 2023View details →

Figure 2 in Abelisauroidea (Theropoda, Dinosauria) from Africa: a review of the fossil record

Figure 2. Map of the Continental Africa and Arabian Peninsula and the African countries that have abelisaur records.

opencc-by-nc-4.0Jul 2023View details →

Figure 3 in Abelisauroidea (Theropoda, Dinosauria) from Africa: a review of the fossil record

Figure 3. Africa abelisauroid record distribution from Late Jurassic to Late Cretaceous, ages from Cohen et al. (2020).