Pink and Dude Chefs: Efficacy of an Online Train-the-Trainer Mechanism and Student Program Outcomes

Background: The rate of overweight and obesity among adolescents aged 12-19 years has quadrupled since 1980. Reducing obesity is a key public health priority, as obesity is associated with individual and population-level health and economic consequences. Afterschool-based obesity prevention programs that aim to develop nutrition and culinary self-efficacy have shown promise. However, the level of aptitude among program instructors is directly correlated with student success, suggesting the importance of effective train-the-trainer (TTT) mechanisms for implementing and scaling up these strategies. Pink and Dude Chefs (PDC) is an afterschool nutrition education and culinary skills program for middle-school adolescents aged between 11-14 years. The PDC online TTT platform trains lay instructors on program content and preparation, lesson delivery, and classroom and kitchen safety. Trained instructors deliver PDC lessons on topics ranging from macronutrients and USDA MyPlate to knife skills and food preparation. The literature on online TTT models and instructor impact on student outcomes is limited and the PDC online training mechanism has not been evaluated. The current project sought to address these critical gaps with the aim of creating the most effective intervention model. Methods: This project was implemented in Santa Maria, Guadalupe, and New Cuyama, California from Fall 2015 to Spring 2016. Eleven instructors and 68 middle school students participated and comprehensive surveys were used to evaluate instructor and student outcomes. Results: Instructors’ performance on all three domains (food and kitchen safety, program knowledge, and overall knowledge) increased following training (45%, 63%, and 53%, respectively), all p≤0.01. Students outcomes (food and kitchen safety, nutrition knowledge, and overall knowledge) also improved following participation (14%, 33%, and 23%, respectively), all p≤0.001. Impact analyses revealed that students with instructors who scored high in overall knowledge performed better than students with low-scoring instructors (p=0.01). Conclusion: If obesity prevention programs that incorporate online TTT mechanisms, such as PDC, continue to show promising outcomes for both instructors and adolescents, larger scale efforts may contribute to decreasing the public health and economic burdens associated with obesity

Regulation of Wages and Hours Prior to 1938

Direct numerical simulations are performed to investigate the transient upstream propagation (flashback) of premixed hydrogen–air flames in the boundary layer of a fully developed turbulent channel flow. Results show that the well-known near-wall velocity fluctuations pattern found in turbulent boundary layers triggers wrinkling of the initially flat flame sheet as it starts propagating against the main flow direction, and that the structure of the characteristic streaks of the turbulent boundary layer ultimately has an important impact on the resulting flame shape and on its propagation mechanism. It is observed that the leading edges of the upstream-propagating premixed flame are always located in the near-wall region of the channel and assume the shape of several smooth, curved bulges propagating upstream side by side in the spanwise direction and convex towards the reactant side of the flame. These leading-edge flame bulges are separated by thin regions of spiky flame cusps pointing towards the product side at the trailing edges of the flame. Analysis of the instantaneous velocity fields clearly reveals the existence, on the reactant side of the flame sheet, of backflow pockets that extend well above the wall-quenching distance. There is a strong correspondence between each of the backflow pockets and a leading edge convex flame bulge. Likewise, high-speed streaks of fast flowing fluid are found to be always colocated with the spiky flame cusps pointing towards the product side of the flame. It is suggested that the origin of the formation of the backflow pockets, along with the subsequent mutual feedback mechanism, is due to the interaction of the approaching streaky turbulent flow pattern with the Darrieus–Landau hydrodynamic instability and pressure fluctuations triggered by the flame sheet. Moreover, the presence of the backflow pockets, coupled with the associated hydrodynamic instability and pressure–flow field interaction, greatly facilitate flame propagation in turbulent boundary layers and ultimately results in high flashback velocities that increase proportionately with pressure

Enabling adaptive scientific workflows via trigger detection

Next generation architectures necessitate a shift away from traditional workflows in which the simulation state is saved at prescribed frequencies for post-processing analysis. While the need to shift to in~situ workflows has been acknowledged for some time, much of the current research is focused on static workflows, where the analysis that would have been done as a post-process is performed concurrently with the simulation at user-prescribed frequencies. Recently, research efforts are striving to enable adaptive workflows, in which the frequency, composition, and execution of computational and data manipulation steps dynamically depend on the state of the simulation. Adapting the workflow to the state of simulation in such a data-driven fashion puts extremely strict efficiency requirements on the analysis capabilities that are used to identify the transitions in the workflow. In this paper we build upon earlier work on trigger detection using sublinear techniques to drive adaptive workflows. Here we propose a methodology to detect the time when sudden heat release occurs in simulations of turbulent combustion. Our proposed method provides an alternative metric that can be used along with our former metric to increase the robustness of trigger detection. We show the effectiveness of our metric empirically for predicting heat release for two use cases.Comment: arXiv admin note: substantial text overlap with arXiv:1506.0825

Missing Lensed Images and the Galaxy Disk Mass in CXOCY J220132.8-320144

The CXOCY J220132.8-320144 system consists of an edge-on spiral galaxy lensing a background quasar into two bright images. Previous efforts to constrain the mass distribution in the galaxy have suggested that at least one additional image must be present (Castander et al. 2006). These extra images may be hidden behind the disk which features a prominent dust lane. We present and analyze Hubble Space Telescope (HST) observations of the system. We do not detect any extra images, but the observations further narrow the observable parameters of the lens system. We explore a range of models to describe the mass distribution in the system and find that a variety of acceptable model fits exist. All plausible models require 2 magnitudes of dust extinction in order to obscure extra images from detection, and some models may require an offset between the center of the galaxy and the center of the dark matter halo of 1 kiloparsec. Currently unobserved images will be detectable by future James Webb Space Telescope (JWST) observations and will provide strict constraints on the fraction of mass in the disk.Comment: 10 pages, 8 figures, 6 tables. Minor changes, version accepted for publication in Ap

Application of PDF mixing models to premixed flames with differential diffusion

Differential diffusion alters the balance of reaction and diffusion in turbulent premixed combustion, affecting the performance and emissions of combustion devices. Modelling combustion devices with Probability or Filtered Density Function (PDF or FDF) methods provides an exact treatment for the change in composition due to chemical reaction, while molecular mixing has to be modelled. Previous PDF molecular mixing models do not account for differential diffusion in a manner which satisfies realizability requirements. A new approach for treating differential diffusion, which ensures realizability, is proposed for pairwise-exchange mixing models in general, and applied in the Interaction by Exchange with the Mean (IEM) model of Dopazo [26], and in the Euclidean Minimum Spanning Tree (EMST) model of Subramaniam and Pope [5]. The new differential diffusion models are referred to as IEM-DD and EMST-DD respectively. Results from two and three-dimensional DNS of turbulent premixed methane–air combustion show that mixing rates and conditional statistics of species mass fractions depend on species diffusivities and the combustion regime. Zero-dimensional PDF model results obtained for the two-dimensional DNS case show that the EMST-DD model best reproduces the features that characterize differential diffusion in the DNS. The essential feature of the EMST-DD model, which accounts for its success in turbulent premixed combustion, is that differential mixing rates are imposed within a model which mixes locally in composition space