Optimizing accuracy and efficacy in data-driven materials discovery for the solar production of hydrogen

The production of hydrogen fuels, via water splitting, is of practical relevance for meeting global energy needs and mitigating the environmental consequences of fossil-fuel-based transportation. Water photoelectrolysis has been proposed as a viable approach for generating hydrogen, provided that stable and inexpensive photocatalysts with conversion efficiencies over 10% can be discovered, synthesized at scale, and successfully deployed (Pinaud et al., Energy Environ. Sci., 2013, 6, 1983). While a number of first-principles studies have focused on the data-driven discovery of photocatalysts, in the absence of systematic experimental validation, the success rate of these predictions may be limited. We address this problem by developing a screening procedure with co-validation between experiment and theory to expedite the synthesis, characterization, and testing of the computationally predicted, most desirable materials. Starting with 70 150 compounds in the Materials Project database, the proposed protocol yielded 71 candidate photocatalysts, 11 of which were synthesized as single-phase materials. Experiments confirmed hydrogen generation and favorable band alignment for 6 of the 11 compounds, with the most promising ones belonging to the families of alkali and alkaline-earth indates and orthoplumbates. This study shows the accuracy of a nonempirical, Hubbard-corrected density-functional theory method to predict band gaps and band offsets at a fraction of the computational cost of hybrid functionals, and outlines an effective strategy to identify photocatalysts for solar hydrogen generation

Sex stereotypes influence adults' perception of babies' cries

Background: Despite widespread evidence that gender stereotypes influence human parental behavior, their potential effects on adults’ perception of babies’ cries have been overlooked. In particular, whether adult listeners overgeneralize the sex dimorphism that characterizes the voice of adult speakers (men are lower-pitched than women) to their perception of babies’ cries has not been investigated. Methods: We used playback experiments combining natural and re-synthesised cries of 3 month-old babies to investigate whether the interindividual variation in the fundamental frequency (pitch) of cries affected adult listeners’ identification of the baby’s sex, their perception the baby’s femininity and masculinity, and whether these biases interacted with their perception of the level of discomfort expressed by the cry. Results: We show that low-pitched cries are more likely to be attributed to boys and high-pitched cries to girls, despite the absence of sex differences in pitch. Moreover, low-pitched boys are perceived as more masculine and high-pitched girls are perceived as more feminine. Finally, adult men rate relatively low-pitched cries as expressing more discomfort when presented as belonging to boys than to girls. Conclusion: Such biases in caregivers’ responses to babies’ cries may have implications on children’s immediate welfare and on the development of their gender identity

SOLUTION APPROACHES TO THE BUS OPERATOR PROBLEM

This study examines traffic equilibrium involving three classes of agents: car users, bus users or passengers and bus operators. A partially unregulated transit system is assumed, where bus fares are exogenously determined by municipal or transportation authorities, but bus operators are allowed to choose the routes where they offer service. This paper deals specifically with the bus operators submodel, for which several algorithms are proposed to find equilibrium solutions. Convergence properties of the proposed algorithms are analyzed and computational results, on both small test networks and the Santiago de Chile urban transit network, are reported. Various methods to deal with the problem posed by limited bus capacities are discussed

Gestational weight gain recommendations for Chilean women: a mathematical optimization approach

Objectives: We examined if the guidelines for gestational weight gain (GWG) proposed by the Institute of Medicine (IOM) are the most suitable for Chilean women. Study design: Secondary analysis of records of single full-term births at the Dr. Sotero del Rio Hospital, Santiago, Chile, during 2003-2012 (n = 62,579). Methods: From clinical records, we obtained data regarding maternal age, height, prepregnancy and at delivery weights, pathologies during pregnancy such as gestational diabetes (GDM) and pre-eclampsia, gestational age at delivery, and number of infants born small for gestational age (SGA) and large for gestational age (LGA). We formulated a mathematical model (MM) to determine the GWG range that maximizes the likelihood of a healthy pregnancy (HP) if the recommendation is followed. We defined an HP as one where the mother has no complications such as pre-eclampsia, GDM, SGA, or LGA. Results: Forty-six percent of women had prepregnancy overweight or obesity. The prevalence of GDM, pre-eclampsia, SGA, and LGA were 3%, 1.2%, 9%, and 12%, respectively. An HP was present in 76% of pregnancies, 79% in the underweight group, 79% in normal weight group, 74% in the overweight group, and 67% in obese women. The GWG recommendations given by the MM (14-20 kg for underweight, 6-20 kg for normal weight, 9 -11 kg for overweight, and 6-7 kg for obese) led to higher probabilities of achieving an HP than the ones obtained with the IOM recommendations. Conclusion: The adoption of GWG recommendations based on characteristics of the Chilean population might lead to better short- and long-term health results for pregnant women

Solution approaches to the bus operator problem

We study urban traffic equilibrium involving three classes of agents: car users, bus users or passengers and bus operators. A partially unregulated transit system is assumed, where bus fares are exogenously determined by municipal or transportation authorities, but bus operators are allowed to choose the routes where they offer service. The paper deals specifically with the bus operators submodel, for which several algorithms are proposed to find equilibrium solutions. Convergence properties of the proposed algorithms are analyzed and computational results, on both small test networks and the Santiago de Chile urban transit network, are reported. Various methods to deal with the problem posed by limited bus capacities are discussed.