Effectiveness and cost of an incentive-based intervention on food safety and income in "dibiteries" in Dakar, Senegal

BACKGROUND: Rapid urbanisation in Sub-Saharan African cities such as Dakar, Senegal, leads to proliferation of informal braised meat restaurants known as "dibiteries". Dibiteries do not often comply with minimal hygiene and food safety standards. The primary objective of this study was to assess the effectiveness and cost of a good hygiene practice intervention, identify factors that incentivize hygiene improvement and how that impacts on dibiteries' income. METHODS: A randomized controlled trial was carried out in Dakar dibiteries. The 120 random samples of braised meat were collected in three phases: (i) one-month pre-intervention, (ii) 2 months post-intervention, (iii) 10 months post-intervention. The trial comprised four groups of 10 dibiteries each: (a) (control) received no intervention, (b) a standardized training module, (c) a hygiene kit, (d) a training module and hygiene kit. Laboratory analysis of samples determined the total aerobic mesophilic flora (TAMF), thermotolerant coliforms (TC) and Staphylococcus aureus (SA). A questionnaire-based survey and focus group discussion were used to identify pre-intervention hygiene practices, and socioeconomic determinants of hygiene management in dibiteries post-intervention, respectively. RESULTS: Samples were found to be contaminated with TAMF, TC and SA. In phase 1, 27 and 13% of the samples contained TC and SA, respectively. In phase 2, no significant improvement of contamination rates was seen. In phase 3, microbiological quality of samples was significantly improved, with only 11.5% showing contamination with any of the bacterial species analysed (p < 0.1). Compared to the control group, only samples from dibiteries in group (b) had significantly reduced bacterial load in phase 3. The cost of intervention and hygiene improvement was estimated at 67 FCFA ($0.12) and 41 FCFA ($ 0.07) / day respectively and did not significantly impact on dibiterie profitability. Incentives to sustainably implement good hygiene practices were mainly linked to access to secure long-term workspaces. CONCLUSION: This intervention may have worked, but globally the results are mixed and not quite significant. However, continuous training in good hygiene practice and access to secure and sustainable infrastructure for dibiterie restaurants are the incentives necessary to achieve sustainable investments and behavioural change. We recommend further intervention refinement and testing other factors for promoting the adoption of good hygiene practices in the dibiteries in relation to consumers health risk

Consumer perception on purchase decision factors and health indicators related to the quality and safety of meat sold in dibiteries in Dakar, Senegal

Accelerated socio-economic and demographic changes have led to the transformation of eating habits in sub-Saharan African cities including Dakar, Senegal. The result is the proliferation of informal fast-food establishments, such as the 'dibiteries' serving braised sheep meat. However, owing to poor hygiene practices, consumption of dibiterie meat poses a public health concern. It was unclear how the dibiterie meat quality and safety were perceived among customers who define their own purchasing social norms. A total of 165 meat consumers were randomly selected and interviewed, from 165 dibiteries sampled by convenience in the Dakar region using a structured questionnaire. Results showed that purchase decisions were guided by trust in the salesperson's expertise, the taste of the product, perceived risk of meat contamination, tenderness, price, the nutritional value, the smell and the colour and freshness of the meat. The perceived quality and safety of dibiterie meat was expressed by the 'organoleptic quality', 'environment and service' and 'price and trust of the product's safety' factors. The majority of consumers (61%) were 'less concerned' about the safety of dibiterie meat, and the acceptable price range of the product was between $5.08 and$7.62. As this food product is gaining popularity in Dakar and the majority of our participating consumers do not show high levels of concern, we suggest stricter standards

Curvature fluctuations and Lyapunov exponent at Melting

We calculate the maximal Lyapunov exponent in constant-energy molecular dynamics simulations at the melting transition for finite clusters of 6 to 13 particles (model rare-gas and metallic systems) as well as for bulk rare-gas solid. For clusters, the Lyapunov exponent generally varies linearly with the total energy, but the slope changes sharply at the melting transition. In the bulk system, melting corresponds to a jump in the Lyapunov exponent, and this corresponds to a singularity in the variance of the curvature of the potential energy surface. In these systems there are two mechanisms of chaos -- local instability and parametric instability. We calculate the contribution of the parametric instability towards the chaoticity of these systems using a recently proposed formalism. The contribution of parametric instability is a continuous function of energy in small clusters but not in the bulk where the melting corresponds to a decrease in this quantity. This implies that the melting in small clusters does not lead to enhanced local instability.Comment: Revtex with 7 PS figures. To appear in Phys Rev

Role of SRC-Family Kinases in Hypoxic Vasoconstriction of Rat Pulmonary Artery

Aims: We investigated the role of src-family kinases (srcFKs) in hypoxic pulmonary vasoconstriction (HPV) and how this relates to Rho-kinase-mediated Ca(2+) sensitization and changes in intracellular Ca(2+) concentration ([Ca(2+)](i)). Methods and results: Intra-pulmonary arteries (IPAs) were obtained from male Wistar rats. HPV was induced in myograph-mounted IPAs. Auto-phosphorylation of srcFKs and phosphorylation of the regulatory subunit of myosin phosphatase (MYPT-1) and myosin light-chain (MLC(20)) in response to hypoxia were determined by western blotting. Translocation of Rho-kinase and effects of siRNA knockdown of src and fyn were examined in cultured pulmonary artery smooth muscle cells (PASMCs). [Ca(2+)](i) was estimated in Fura-PE3-loaded IPA. HPV was inhibited by two blockers of srcFKs, SU6656 and PP2. Hypoxia enhanced phosphorylation of three srcFK proteins at Tyr-416 (60, 59, and 54 kDa, corresponding to src, fyn, and yes, respectively) and enhanced srcFK-dependent tyrosine phosphorylation of multiple target proteins. Hypoxia caused a complex, time-dependent enhancement of MYPT-1 and MLC(20) phosphorylation, both in the absence and presence of pre-constriction. The sustained component of this enhancement was blocked by SU6656 and the Rho-kinase inhibitor Y27632. In PASMCs, hypoxia caused translocation of Rho-kinase from the nucleus to the cytoplasm, and this was prevented by anti-src siRNA and to a lesser extent by anti-fyn siRNA. The biphasic increases in [Ca(2+)](i) that accompany HPV were also inhibited by PP2. Conclusion: Hypoxia activates srcFKs and triggers protein tyrosine phosphorylation in IPA. Hypoxia-mediated Rho-kinase activation, Ca(2+) sensitization, and [Ca(2+)](i) responses are depressed by srcFK inhibitors and/or siRNA knockdown, suggesting a central role of srcFKs in HPV

Big-Data-Driven Materials Science and its FAIR Data Infrastructure

This chapter addresses the forth paradigm of materials research -- big-data driven materials science. Its concepts and state-of-the-art are described, and its challenges and chances are discussed. For furthering the field, Open Data and an all-embracing sharing, an efficient data infrastructure, and the rich ecosystem of computer codes used in the community are of critical importance. For shaping this forth paradigm and contributing to the development or discovery of improved and novel materials, data must be what is now called FAIR -- Findable, Accessible, Interoperable and Re-purposable/Re-usable. This sets the stage for advances of methods from artificial intelligence that operate on large data sets to find trends and patterns that cannot be obtained from individual calculations and not even directly from high-throughput studies. Recent progress is reviewed and demonstrated, and the chapter is concluded by a forward-looking perspective, addressing important not yet solved challenges.Comment: submitted to the Handbook of Materials Modeling (eds. S. Yip and W. Andreoni), Springer 2018/201

Defining Developmental Potency and Cell Lineage Trajectories by Expression Profiling of Differentiating Mouse Embryonic Stem Cells

Biologists rely on morphology, function and specific markers to define the differentiation status of cells. Transcript profiling has expanded the repertoire of these markers by providing the snapshot of cellular status that reflects the activity of all genes. However, such data have been used only to assess relative similarities and differences of these cells. Here we show that principal component analysis of global gene expression profiles map cells in multidimensional transcript profile space and the positions of differentiating cells progress in a stepwise manner along trajectories starting from undifferentiated embryonic stem (ES) cells located in the apex. We present three ‘cell lineage trajectories’, which represent the differentiation of ES cells into the first three lineages in mammalian development: primitive endoderm, trophoblast and primitive ectoderm/neural ectoderm. The positions of the cells along these trajectories seem to reflect the developmental potency of cells and can be used as a scale for the potential of cells. Indeed, we show that embryonic germ cells and induced pluripotent cells are mapped near the origin of the trajectories, whereas mouse embryo fibroblast and fibroblast cell lines are mapped near the far end of the trajectories. We suggest that this method can be used as the non-operational semi-quantitative definition of cell differentiation status and developmental potency. Furthermore, the global expression profiles of cell lineages provide a framework for the future study of in vitro and in vivo cell differentiation

Reactions to Brexit in images : a multimodal content analysis of shared visual content on Flickr

In this article, the authors analyze citizens’ reactions to Brexit on social media after the referendum results by performing a content analysis of 5877 posts collected from the social media platform Flickr, written in English, German, French, Spanish or Italian. Their research aims to answer the three following questions: What multimodal practices are adopted by citizens when they react to societal events like Brexit? To what extent do these practices illustrate types of citizenship that are specific to social networks? Can we observe different reactions to Brexit according to the languages used by the citizens? The authors focus on the types of visual content the citizens used to react to Brexit, as well as on what types of social relations this content can particularly create between their authors and the other members of the Flick community. Their article also highlights to what extent these posts shared on Flickr show content that is in favour of, or against, Brexit

Optomechanical response with nanometer resolution in the self-mixing signal of a terahertz quantum cascade laser

Owing to their intrinsic stability against optical feedback (OF), quantum cascade lasers (QCLs) represent a uniquely versatile source to further improve self-mixing interferometry at mid-infrared and terahertz (THz) frequencies. Here, we show the feasibility of detecting with nanometer precision, the deeply subwavelength ($\lt \lambda /6000$<λ/6000) mechanical vibrations of a suspended ${{\rm Si}_3}{{\rm N}_4}$Si3N4 membrane used as the external element of a THz QCL feedback interferometer. Besides representing an extension of the applicability of vibrometric characterization at THz frequencies, our system can be exploited for the realization of optomechanical applications, such as dynamical switching between different OF regimes and a still-lacking THz master-slave configuration

Sodium Selenide Toxicity Is Mediated by O2-Dependent DNA Breaks

Hydrogen selenide is a recurrent metabolite of selenium compounds. However, few experiments studied the direct link between this toxic agent and cell death. To address this question, we first screened a systematic collection of Saccharomyces cerevisiae haploid knockout strains for sensitivity to sodium selenide, a donor for hydrogen selenide (H2Se/HSe−/Se2−). Among the genes whose deletion caused hypresensitivity, homologous recombination and DNA damage checkpoint genes were over-represented, suggesting that DNA double-strand breaks are a dominant cause of hydrogen selenide toxicity. Consistent with this hypothesis, treatment of S. cerevisiae cells with sodium selenide triggered G2/M checkpoint activation and induced in vivo chromosome fragmentation. In vitro, sodium selenide directly induced DNA phosphodiester-bond breaks via an O2-dependent reaction. The reaction was inhibited by mannitol, a hydroxyl radical quencher, but not by superoxide dismutase or catalase, strongly suggesting the involvement of hydroxyl radicals and ruling out participations of superoxide anions or hydrogen peroxide. The •OH signature could indeed be detected by electron spin resonance upon exposure of a solution of sodium selenide to O2. Finally we showed that, in vivo, toxicity strictly depended on the presence of O2. Therefore, by combining genome-wide and biochemical approaches, we demonstrated that, in yeast cells, hydrogen selenide induces toxic DNA breaks through an O2-dependent radical-based mechanism