Noise transfer for unsupervised domain adaptation of retinal OCT images

Optical coherence tomography (OCT) imaging from different camera devices causes challenging domain shifts and can cause a severe drop in accuracy for machine learning models. In this work, we introduce a minimal noise adaptation method based on a singular value decomposition (SVDNA) to overcome the domain gap between target domains from three different device manufacturers in retinal OCT imaging. Our method utilizes the difference in noise structure to successfully bridge the domain gap between different OCT devices and transfer the style from unlabeled target domain images to source images for which manual annotations are available. We demonstrate how this method, despite its simplicity, compares or even outperforms state-of-the-art unsupervised domain adaptation methods for semantic segmentation on a public OCT dataset. SVDNA can be integrated with just a few lines of code into the augmentation pipeline of any network which is in contrast to many state-of-the-art domain adaptation methods which often need to change the underlying model architecture or train a separate style transfer model. The full code implementation for SVDNA is available at https://github.com/ValentinKoch/SVDNA.Comment: published at MICCAI 202

Adapting to Fuelwood Scarcity: The Farmers' Perspective

About 3 billion people worldwide depend on fuelwood to meet their domestic energy needs. Almost 90% of the population in Sub-Saharan Africa use fuelwood-based forms of energy. However, its use is often unsustainable and is one driver of environmental degradation. In Tanzania, the majority of rural residents depend on fuelwood as their major source of cooking energy. The adaptation measures applied by small-scale farmers in response to fuelwood scarcity are typically unsustainable with regard to socio-economic, environmental, and food security dimensions. This study applies a methodological framework that assesses the personally experienced impact of coping strategies by local stakeholders on sustainability criteria. This framework comprises (1) the selection of appropriate adaptation measures; (2) the identification of local sustainability criteria; and (3) the participatory impact and frequency assessments at two case study sites in the semi-arid region of Dodoma in central Tanzania. Overall, eight coping strategies from 23 measures applied in the region were selected and four sustainability criteria defined by local key informants were identified. The participatory impact and frequency assessment show that the strategies of “on-farm tree planting” and “use of improved cooking stoves” are rated as positive across all four sustainability criteria and are regularly applied by the farmers. Two of the eight strategies are clearly negative: “eat fewer meals” and “increase in walking distance to collect fuelwood.” These measures are regularly and widely used by farmers, thus amplifying the negative rating. Overall, the experiences of farmers suggest that applied coping strategies have the greatest negative effect on the environmental condition and, on average, a rather positive effect on economic conditions. The results offer an approach for developing a reliable monitoring of how adaptation measures are applied in response to fuelwood scarcity and to achieve distinct values for benchmarking

Editorial: Achieving nutrition security in Tanzania by improving production, education and economics: Methods, tools and applications

Peer Reviewe

Maize-Pigeonpea Intercropping Outperforms Monocultures Under Drought

There is an urgent need to develop resilient agroecosystems capable of helping smallholder farmers adapt to climate change, particularly drought. In East Africa, diversification of maize-based cropping systems by intercropping with grain and tree legumes may foster productivity and resilience to adverse weather conditions. We tested whether intercropping enhances drought resistance and crop and whole-system yields by imposing drought in monocultures and additive intercrops along a crop diversity gradient—sole maize (Zea mays), sole pigeonpea (Cajanus cajan), maize-pigeonpea, maize-gliricidia (Gliricidia sepium, a woody perennial), and maize-pigeonpea-gliricidia—with and without fertilizer application. We developed and tested a novel low-cost, above-canopy rainout shelter design for drought experiments made with locally-sourced materials that successfully reduced soil moisture without creating sizeable artifacts for the crop microenvironment. Drought reduced maize grain yield under fertilized conditions in some cropping systems but did not impact pigeonpea grain yield. Whole-system grain yield and theoretical caloric and protein yields in two intercropping systems, maize-pigeonpea and maize-gliricidia, were similar to the standard sole maize system. Maize-pigeonepea performed most strongly compared to other systems in terms of protein yield. Maize-pigeonpea was the only intercrop that consistently required less land than its corresponding monocultures to produce the same yield (Land Equivalent Ratio >1), particularly under drought. Despite intercropping systems having greater planting density than sole maize and theoretically greater competition for water, they were not more prone to yield loss with drought. Our results show that maize-pigeonpea intercropping provides opportunities to produce the same food on less land under drought and non-drought conditions, without compromising drought resistance of low-input smallholder maize system

Allometric equations for estimating on-farm fuel production of Gliricidia sepium (Gliricidia) shrubs and Cajanus cajan (pigeon pea) plants in semi-arid Tanzania

BACKGROUND: Fuelwood is considered to be the primary source of cooking energy in Tanzania and, due to ongoing deforestation, access to fuelwood is becoming more cumbersome. On-farm agroforestry systems can reduce dependency on off-farm fuel; however, the output of on-farm produced fuel is typically uncertain as production potentials are often not known. In this paper, we have developed allometric equations to model the above-ground woody biomass (AGWB) production from intercropped Gliricidia sepium (Jacq.) Kunth ex Walp (Gliricidia) shrubs and Cajanus cajan (L.) Millsp. (pigeon pea) plants. METHODS: We used a destructive sampling approach, for measuring the dendrometric characteristics, such as the root collar diameter at a 20 cm stem height (RCD20) and the stem height to estimate the AGWB production. The models are based on 112 Gliricidia and 80 pigeon pea observations from annually pruned plants. Seven allometric equations were fitted to derive the best-fit models for the AGWB production. RESULTS: We found that using a natural log-transformed linear model with RCD20 as a single predictor variable provides the highest explanatory value to estimate the AGWB production (Gliricidia: R2 = 95.7%, pigeon pea: R2 = 91.4%) while meeting Ordinary Least Square (OLS) estimator requirements. Adding stem height as an additional variable to predict the AGWB production does not improve model accuracy enough to justify the extra work for including it. CONCLUSIONS: While on-farm pigeon pea plants produced a stable amount of woody biomass per annum, annual fuelwood production from Gliricidia shrubs increased over the years. Compared to the annual fuelwood consumption data from the literature, our results show that on-farm produced fuelwood can substantially offset the demand for off-farm fuel, potentially resulting in household fuelwood autarky

Nationwide German Multicenter Study on Prevalence of Antibiotic Resistance in Staphylococcal Bloodstream Isolates and Comparative In Vitro Activities of Quinupristin-Dalfopristin

Antibiotic-resistant gram-positive bacteria have become an increasing problem in the last two decades. In order to evaluate the prevalence of antibiotic resistance in staphylococcal bloodstream isolates in Germany, 2,042 staphylococci collected in 21 tertiary-care hospitals were investigated during a 3-year period (March 1996 to March 1999). Altogether, 1,448 S. aureus isolates and 594 coagulase-negative staphylococci (CoNS) that comprised 13 different species were included. Furthermore, the antistaphylococcal activities of quinupristin-dalfopristin were compared with those of eight other compounds by the broth microdilution method. The rates of oxacillin resistance in Staphylococcus aureus, S. epidermidis, S. haemolyticus, and other CoNS were 13.5, 69, 90, and 34%, respectively. In oxacillin-resistant strains high rates of resistance (up to 100%) to erythromycin, clindamycin, ciprofloxacin, and gentamicin were also observed. However, no strain appeared to be resistant to vancomycin or quinupristin-dalfopristin. The streptogramin combination exhibited excellent in vitro activity against all staphylococcal species tested, regardless of the patterns of resistance to other drug classes. In terms of MICs at which 90% of the isolates are inhibited, quinupristin-dalfopristin was 2 times more active against S. aureus isolates, 4 to 16 times more active against S. haemolyticus, and 8 to 32 times more active against S. epidermidis than vancomycin or teicoplanin

Development of an integrated assessment framework for agroforestry technologies: assessing sustainability, barriers, and impacts in the semi-arid region of Dodoma, Tanzania

Land degradation continues to be a major concern for agriculture in developing countries, including Tanzania. Agroforestry is one solution that benefits food production and reduces land degradation. However, various challenges hinder its widespread adoption. This study uses an integrated assessment framework, combining MESMIS (an indicator-based sustainability assessment framework) and ScalA (a scaling-up assessment tool), to evaluate sustainability and constraints to the widespread implementation of agroforestry in semi-arid Tanzania. The main goals are to: 1) identify existing agroforestry technologies adopted by smallholder farmers; 2) evaluate farmers’ perception of sustainability regarding each technology's environmental, economic, and social impact; and 3) identify constraints related to the widespread adoption. Results show that farmers consider the following four technologies as the most sustainable: (i) tied ridge + tree intercropping; (ii) contour planting + tree intercropping; (iii) Chololo pits + tree intercropping; and (iv) tree intercropping alone. The findings indicate that, although farmers perceive the technologies positively, adoption is also influenced by local climate, socio-economic status, and institutional factors. The study highlights that a positive perception alone cannot ensure widespread adoption, emphasizing the importance of considering contextual factors. Further testing and application of the proposed framework in similar and comparative settings is encouraged as it provides valuable guidance when evaluating different agroecosystems holistically

Four years of sustainability impact assessments accompanying the implementation of improved cooking stoves in Tanzania

Development projects and innovations are often implemented based on scientific recommendations and do not incorporate local knowledge and demand for interventions. In this paper, we demonstrate the successful engagement of local stakeholders in the implementation and evaluation process of improved cooking stoves; a technology that improves food security in two climatically contrasting regions in Tanzania. The Framework for Participatory Impact Assessment tool was used to conduct impact assessments on firewood-based improved cooking stoves to evaluate their contribution to food security at local stakeholder level. Between 2014 and 2017, four annual impact assessments were conducted with local stakeholders in four villages in the semi-arid Dodoma and the sub-humid Morogoro regions to assess the impact of improved cooking stoves on locally defined nine food security criteria. The Framework for Participatory Impact Assessment was used to (i) ex-ante identify the expected impact, and (ii) to ex-post assess the experienced impact of improved cooking stoves on the nine food security criteria. The impact assessments showed that the perceived contribution of improved cooking stoves towards the food security criteria was positive throughout all assessments. In particular, improved cooking stoves addressed relevant food security criteria such as social relations, food availability, and market participation. The Framework for Participatory Impact Assessment tool supported continuous knowledge exchange between scientists and local stakeholders, thus improving communication and co-learning; while identifying merits and demerits of the improved cooking stoves that could be addressed during the project lifetime