Towards a machine learning model for explicit algebraic Reynolds stress modelling using multi-expression programming

A novel framework for a 5-term explicit algebraic Reynolds stress model has been proposed, which is suitable for machine learning procedures. Under this framework, high-fidelity datasets have been explored and post-processed. Through multi-expression programming, models have been obtained using these data. They have been thoroughly tested and present all the desirable features of a model. Implementation of these models in a numerical code has also been possible. Results have shown that they present a small upgrade over classical models for certain kinds of flows, thus showing that the physics have been captured well. It is proved that the present workflow can obtain valid expressions with similar to better performance than the baseline model.The research leading to this work has received funding within the HiFi-TURB project from the European Union’s Horizon2020 research and innovation programme under grant agreement No 814837. Oriol Lehmkuhl has been partially supported by a Ramon y Cajal postdoctoral contract (Ref: RYC2018-025949-I).Peer ReviewedPostprint (published version

The contribution of HIV to pregnancy-related mortality: a systematic review and meta-analysis.

OBJECTIVES: Although much is known about the contribution of HIV to adult mortality, remarkably little is known about the mortality attributable to HIV during pregnancy. In this article we estimate the proportion of pregnancy-related deaths attributable to HIV based on empirical data from a systematic review of the strength of association between HIV and pregnancy-related mortality. METHODS: Studies comparing mortality during pregnancy and the postpartum in HIV-infected and HIV-uninfected women were included. Summary estimates of the relative and attributable risks for the association between HIV and pregnancy-related mortality were calculated through meta-analyses. Varying estimates of HIV prevalence were used to predict the impact of the HIV epidemic on pregnancy-related mortality at the population level. RESULTS: Twenty-three studies were included (17 from sub-Saharan Africa). Meta-analysis of the risk ratios indicated that HIV-infected women had eight times the risk of a pregnancy-related death compared with HIV-uninfected women [pooled risk ratio 7.74, 95% confidence interval (95% CI) 5.37-11.16]. The excess mortality attributable to HIV among HIV-infected pregnant and postpartum women was 994 per 100,000 pregnant women. We predict that 12% of all deaths during pregnancy and up to 1-year postpartum are attributable to HIV/AIDS in regions with a prevalence of HIV among pregnant women of 2%. This figure rises to 50% in regions with a prevalence of 15%. CONCLUSION: The substantial excess of pregnancy-related mortality associated with HIV highlights the importance of integrating HIV and reproductive health services in areas of high HIV prevalence and pregnancy-related mortality

HIV and the risk of direct obstetric complications: a systematic review and meta-analysis.

BACKGROUND: Women of reproductive age in parts of sub-Saharan Africa are faced both with high levels of HIV and the threat of dying from the direct complications of pregnancy. Clinicians practicing in such settings have reported a high incidence of direct obstetric complications among HIV-infected women, but the evidence supporting this is unclear. The aim of this systematic review is to establish whether HIV-infected women are at increased risk of direct obstetric complications. METHODS AND FINDINGS: Studies comparing the frequency of obstetric haemorrhage, hypertensive disorders of pregnancy, dystocia and intrauterine infections in HIV-infected and uninfected women were identified. Summary estimates of the odds ratio (OR) for the association between HIV and each obstetric complication were calculated through meta-analyses. In total, 44 studies were included providing 66 data sets; 17 on haemorrhage, 19 on hypertensive disorders, five on dystocia and 25 on intrauterine infections. Meta-analysis of the OR from studies including vaginal deliveries indicated that HIV-infected women had over three times the risk of a puerperal sepsis compared with HIV-uninfected women [pooled OR: 3.43, 95% confidence interval (CI): 2.00-5.85]; this figure increased to nearly six amongst studies only including women who delivered by caesarean (pooled OR: 5.81, 95% CI: 2.42-13.97). For other obstetric complications the evidence was weak and inconsistent. CONCLUSIONS: The higher risk of intrauterine infections in HIV-infected pregnant and postpartum women may require targeted strategies involving the prophylactic use of antibiotics during labour. However, as the huge excess of pregnancy-related mortality in HIV-infected women is unlikely to be due to a higher risk of direct obstetric complications, reducing this mortality will require non obstetric interventions involving access to ART in both pregnant and non-pregnant women