Effect of input credit on smallholder farmers’ output and income: Evidence from Northern Ghana

Purpose The purpose of this paper is to examine the effect of input credit on smallholder farmers’ output and income using Masara N’Arziki support project in Northern Ghana. Design/methodology/approach A cross-sectional primary data set was used to estimate the effect of project participation on farm output, yield and income using propensity score matching (PSM) methods. Findings The findings are that project participation is skewed towards experienced farmers with big-sized households and farms. The effect of project on outcomes is somewhat unsatisfactory in the sense that participation only raises output and yield, but not income. Research limitations/implications The paper only examined the project effect on farm outcomes among smallholder farmers participating in the programme in just one operational area in the Northern region. Future research should consider all the operational areas for an informed generalisation of findings. Practical implications Greater benefits to farmers from programme participation would require project management to review the contractual arrangement so that the high cost of input credit is significantly reduced. Originality/value The paper applied the PSM to estimate the effect of project participation on farm output, yield and income among smallholder farmers which is non-existent in the literature on the study area, at least as far as we know. This paper can inform future policy on the direction and nature of support for smallholder farmers in Northern Ghana

Primary beam effects of radio astronomy antennas -- II. Modelling the MeerKAT L-band beam

After a decade of design and construction, South Africa's SKA-MID precursor MeerKAT has begun its science operations. To make full use of the widefield capability of the array, it is imperative that we have an accurate model of the primary beam of its antennas. We have taken available L-band full-polarization 'astro-holographic' observations of three antennas and a generic electromagnetic simulation and created sparse representations of the beams using principal components and Zernike polynomials. The spectral behaviour of the spatial coefficients has been modelled using discrete cosine transform. We have provided the Zernike-based model over a diameter of 10 deg averaged over the beams of three antennas in an associated software tool (EIDOS) that can be useful in direction-dependent calibration and imaging. The model is more accurate for the diagonal elements of the beam Jones matrix and at lower frequencies. As we get more accurate beam measurements and simulations in the future, especially for the cross-polarization patterns, our pipeline can be used to create more accurate sparse representations of MeerKAT beams.Comment: 16 pages, 18 figures. This is a pre-copyedited, author-produced PDF of an article accepted for publication in MNRAS following peer review. The version of record [K. M. B. Asad et al., 2021] is available online at: https://doi.org/10.1093/mnras/stab10

Connexin-43 prevents hematopoietic stem cell senescence through transfer of reactive oxygen species to bone marrow stromal cells

Hematopoietic stem cell (HSC) aging has become a concern in chemotherapy of older patients. Humoral and paracrine signals from the bone marrow (BM) hematopoietic microenvironment (HM) control HSC activity during regenerative hematopoiesis. Connexin-43 (Cx43), a connexin constituent of gap junctions (GJs) is expressed in HSCs, down-regulated during differentiation, and postulated to be a self-renewal gene. Our studies, however, reveal that hematopoietic-specific Cx43 deficiency does not result in significant long-term competitive repopulation deficiency. Instead, hematopoietic Cx43 (H-Cx43) deficiency delays hematopoietic recovery after myeloablation with 5-fluorouracil (5-FU). 5-FU-treated H-Cx43-deficient HSC and progenitors (HSC/P) cells display decreased survival and fail to enter the cell cycle to proliferate. Cell cycle quiescence is associated with down-regulation of cyclin D1, up-regulation of the cyclin-dependent kinase inhibitors, p21cip1. and p16INK4a, and Forkhead transcriptional factor 1 (Foxo1), and activation of p38 mitogen-activated protein kinase (MAPK), indicating that H-Cx43-deficient HSCs are prone to senescence. The mechanism of increased senescence in H-Cx43-deficient HSC/P cells depends on their inability to transfer reactive oxygen species (ROS) to the HM, leading to accumulation of ROS within HSCs. In vivo antioxidant administration prevents the defective hematopoietic regeneration, as well as exogenous expression of Cx43 in HSC/P cells. Furthermore, ROS transfer from HSC/P cells to BM stromal cells is also rescued by reexpression of Cx43 in HSC/P. Finally, the deficiency of Cx43 in the HM phenocopies the hematopoietic defect in vivo. These results indicate that Cx43 exerts a protective role and regulates the HSC/P ROS content through ROS transfer to the HM, resulting in HSC protection during stress hematopoietic regeneration

An Economic Evaluation of Home Management of Malaria in Uganda: An Interactive Markov Model

BACKGROUND: Home management of malaria (HMM), promoting presumptive treatment of febrile children in the community, is advocated to improve prompt appropriate treatment of malaria in Africa. The cost-effectiveness of HMM is likely to vary widely in different settings and with the antimalarial drugs used. However, no data on the cost-effectiveness of HMM programmes are available. METHODS/PRINCIPAL FINDINGS: A Markov model was constructed to estimate the cost-effectiveness of HMM as compared to conventional care for febrile illnesses in children without HMM. The model was populated with data from Uganda, but is designed to be interactive, allowing the user to adjust certain parameters, including the antimalarials distributed. The model calculates the cost per disability adjusted life year averted and presents the incremental cost-effectiveness ratio compared to a threshold value. Model output is stratified by level of malaria transmission and the probability that a child would receive appropriate care from a health facility, to indicate the circumstances in which HMM is likely to be cost-effective. The model output suggests that the cost-effectiveness of HMM varies with malaria transmission, the probability of appropriate care, and the drug distributed. Where transmission is high and the probability of appropriate care is limited, HMM is likely to be cost-effective from a provider perspective. Even with the most effective antimalarials, HMM remains an attractive intervention only in areas of high malaria transmission and in medium transmission areas with a lower probability of appropriate care. HMM is generally not cost-effective in low transmission areas, regardless of which antimalarial is distributed. Considering the analysis from the societal perspective decreases the attractiveness of HMM. CONCLUSION: Syndromic HMM for children with fever may be a useful strategy for higher transmission settings with limited health care and diagnosis, but is not appropriate for all settings. HMM may need to be tailored to specific settings, accounting for local malaria transmission intensity and availability of health services

A Cluster Randomised Trial Introducing Rapid Diagnostic Tests into Registered Drug Shops in Uganda: Impact on Appropriate Treatment of Malaria

Background: Inappropriate treatment of malaria is widely reported particularly in areas where there is poor access to health facilities and self-treatment of fevers with anti-malarial drugs bought in shops is the most common form of care-seeking. The main objective of the study was to examine the impact of introducing rapid diagnostic tests for malaria (mRDTs) in registered drug shops in Uganda, with the aim to increase appropriate treatment of malaria with artemisinin-based combination therapy (ACT) in patients seeking treatment for fever in drug shops. Methods: A cluster-randomized trial of introducing mRDTs in registered drug shops was implemented in 20 geographical clusters of drug shops in Mukono district, central Uganda. Ten clusters were randomly allocated to the intervention (diagnostic confirmation of malaria by mRDT followed by ACT) and ten clusters to the control arm (presumptive treatment of fevers with ACT). Treatment decisions by providers were validated by microscopy on a reference blood slide collected at the time of consultation. The primary outcome was the proportion of febrile patients receiving appropriate treatment with ACT defined as: malaria patients with microscopically-confirmed presence of parasites in a peripheral blood smear receiving ACT or rectal artesunate, and patients with no malaria parasites not given ACT. Findings: A total of 15,517 eligible patients (8672 intervention and 6845 control) received treatment for fever between January-December 2011. The proportion of febrile patients who received appropriate ACT treatment was 72·9% versus 33·7% in the control arm; a difference of 36·1% (95% CI: 21·3 – 50·9), p<0·001. The majority of patients with fever in the intervention arm accepted to purchase an mRDT (97·8%), of whom 58·5% tested mRDT-positive. Drug shop vendors adhered to the mRDT results, reducing over-treatment of malaria by 72·6% (95% CI: 46·7– 98·4), p<0·001) compared to drug shop vendors using presumptive diagnosis (control arm). Conclusion: Diagnostic testing with mRDTs compared to presumptive treatment of fevers implemented in registered drug shops substantially improved appropriate treatment of malaria with ACT

Promoting Drp1-mediated mitochondrial fission in midlife prolongs healthy lifespan of Drosophila melanogaster

The accumulation of dysfunctional mitochondria has been implicated in aging, but a deeper understanding of mitochondrial dynamics and mitophagy during aging is missing. Here, we show that upregulating Drp1—a Dynamin-related protein that promotes mitochondrial fission—in midlife, prolongs Drosophila lifespan and healthspan. We find that short-term induction of Drp1, in midlife, is sufficient to improve organismal health and prolong lifespan, and observe a midlife shift toward a more elongated mitochondrial morphology, which is linked to the accumulation of dysfunctional mitochondria in aged flight muscle. Promoting Drp1-mediated mitochondrial fission, in midlife, facilitates mitophagy and improves both mitochondrial respiratory function and proteostasis in aged flies. Finally, we show that autophagy is required for the anti-aging effects of midlife Drp1-mediated mitochondrial fission. Our findings indicate that interventions that promote mitochondrial fission could delay the onset of pathology and mortality in mammals when applied in midlife

Mutations in the Mitochondrial Methionyl-tRNA Synthetase Cause a Neurodegenerative Phenotype in Flies and a Recessive Ataxia (ARSAL) in Humans

The study of Drosophila neurodegenerative mutants combined with genetic and biochemical analyses lead to the identification of multiple complex mutations in 60 patients with a novel form of ataxia/leukoencephalopathy

Potentiation of Epithelial Innate Host Responses by Intercellular Communication

The epithelium efficiently attracts immune cells upon infection despite the low number of pathogenic microbes and moderate levels of secreted chemokines per cell. Here we examined whether horizontal intercellular communication between cells may contribute to a coordinated response of the epithelium. Listeria monocytogenes infection, transfection, and microinjection of individual cells within a polarized intestinal epithelial cell layer were performed and activation was determined at the single cell level by fluorescence microscopy and flow cytometry. Surprisingly, chemokine production after L. monocytogenes infection was primarily observed in non-infected epithelial cells despite invasion-dependent cell activation. Whereas horizontal communication was independent of gap junction formation, cytokine secretion, ion fluxes, or nitric oxide synthesis, NADPH oxidase (Nox) 4-dependent oxygen radical formation was required and sufficient to induce indirect epithelial cell activation. This is the first report to describe epithelial cell-cell communication in response to innate immune activation. Epithelial communication facilitates a coordinated infectious host defence at the very early stage of microbial infection

Mitochondrial Variability as a Source of Extrinsic Cellular Noise

We present a study investigating the role of mitochondrial variability in generating noise in eukaryotic cells. Noise in cellular physiology plays an important role in many fundamental cellular processes, including transcription, translation, stem cell differentiation and response to medication, but the specific random influences that affect these processes have yet to be clearly elucidated. Here we present a mechanism by which variability in mitochondrial volume and functionality, along with cell cycle dynamics, is linked to variability in transcription rate and hence has a profound effect on downstream cellular processes. Our model mechanism is supported by an appreciable volume of recent experimental evidence, and we present the results of several new experiments with which our model is also consistent. We find that noise due to mitochondrial variability can sometimes dominate over other extrinsic noise sources (such as cell cycle asynchronicity) and can significantly affect large-scale observable properties such as cell cycle length and gene expression levels. We also explore two recent regulatory network-based models for stem cell differentiation, and find that extrinsic noise in transcription rate causes appreciable variability in the behaviour of these model systems. These results suggest that mitochondrial and transcriptional variability may be an important mechanism influencing a large variety of cellular processes and properties