93 research outputs found

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

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    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

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    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

    Is bigger better? Metropolitan area population, access, activity participation, and subjective well-being

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    Researchers have posited that larger, denser metropolitan areas have important consumption advantages. We examine this using Cragg two-part hurdle and ordinary least square (OLS) regression models employing data from the American Time Use Survey. We test whether: 1) large metropolitan area residents participate in more out-of-home activities because these activities are more plentiful, richer, and/or easier to access, 2) large metropolitan areas have lower travel times because of higher densities, and 3) activities in larger metropolitan areas have more positive associations with subjective well-being than those in smaller places. We reject all three hypotheses. Metropolitan area population size is largely unrelated to time spent outside the home, excluding travel. Large-metropolitan-area residents participate in more arts and entertainment activities and eat and drink out more often, but they socialize, volunteer, and care for others outside the home less. Larger metropolitan areas are associated with dramatically more travel time. We find no evidence that large metropolitan area activities contribute any more or less to life satisfaction or affect than activities in smaller places. We also find that life satisfaction does not covary with metropolitan area size. In sum, living in a large metropolitan area may primarily involve a tradeoff of (travel) time for money (higher wages), with little net change in welfare

    The EU’s General Data Protection Regulation (GDPR) in a Research Context

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    This chapter introduces the rational and regulatory mechanism underlying the EU data protection framework with specific focus on the EU’s General Data Protection Regulation (GDPR). It outlines the applicability of the research exemption included in the GDPR and discusses further or secondary use of personal data for research purposes

    SOLUTION APPROACHES TO THE BUS OPERATOR PROBLEM

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    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

    Operating room scheduling under waiting time constraints: the Chilean GES plan

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    In 2000, Chile introduced profound health reforms to achieve a more equitable and fairer system (GES plan). The reforms established a maximum waiting time between diagnosis and treatment for a set of diseases, described as an opportunity guarantee within the reform. If the maximum waiting time is exceeded, the patient is referred to another (private) facility and receives a voucher to cover the additional expenses. This voucher is paid by the health provider that had to do the procedure, which generally is a public hospital. In general, this reform has improved the service for patients with GES pathologies at the expense of patients with non-GES pathologies. These new conditions create a complicated planning scenario for hospitals, in which the hospital's OR Manager must balance the fulfillment of these opportunity guarantees and the timely service of patients not covered by the guarantee. With the collaboration of the Instituto de Neurocirugia, in Santiago, Chile, we developed a mathematical model based on stochastic dynamic programming to schedule surgeries in order to minimize the cost of referrals to the private sector. Given the large size of the state space, we developed an heuristic to compute good solutions in reasonable time and analyzed its performance. Our experimental results, with both simulated and real data, show that our algorithm performs close to optimum and improves upon the current practice. When we compared the results of our heuristic against those obtained by the hospital's OR manager in a simulation setting with real data, we reduced the overtime from occurring 21% of the time to zero, and the non-GES average waiting list's length from 71 to 58 patients, without worsening the average throughput
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