Systematic two-dimensional cascade tests. Volume 1 - Double circular-arc hydrofoils

Performance perameters and incipient cavitation indices for double circular-arc hydrofoil tests with configurations for cascade flow in hydraulic test tunnel

Player retention in league of legends: A study using survival analysis

© 2018 ACM. Multi-player online esports games are designed for extended durations of play, requiring substantial experience to master. Furthermore, esports game revenues are increasingly driven by in-game purchases. For esports companies, the trends in players leaving their games therefore not only provide information about potential problems in the user experience, but also impacts revenue. Being able to predict when players are about to leave the game-churn prediction-is therefore an important solution for companies in the rapidly growing esports sector, as this allows them to take action to remedy churn problems. The objective of the work presented here is to understand the impact of specific behavioral characteristics on the likelihood of a player continuing to play the esports title League of Legends. Here, a solution to the problem is presented based on the application of survival analysis, using Mixed Effects Cox Regression, to predict player churn. Survival Analysis forms a useful approach for the churn prediction problem as it provides rates as well as an assessment of the characteristics of players who are at risk of leaving the game. Hazard rates are also presented for the leading indicators, with results showing that duration between matches played is a strong indicator of potential churn

Diminished conditioned responding to the nicotine stimulus by antidepressant drugs with differing specificity for the serotonin and norepinephrine transporter

People diagnosed with depression also tend to have a co-morbid nicotine addiction. Thus, there is interest in whether medications used to treat depression alter the effects of nicotine. This study assessed whether the antidepressant drugs citalopram, imipramine, and reboxetine, with differing specificity for the serotonin and norepinephrine transporter, altered responding controlled by the conditional stimulus (CS) effects of nicotine. Rats received intermixed 20-min nicotine (0.4 mg base/kg, SC) and saline sessions. On nicotine sessions, rats had intermittent access to sucrose; no sucrose was available on saline sessions. After discrimination performance stabilized and a nicotine generalization curve (0.025–0.4 mg/kg) was established, the antidepressant drugs were assessed. In these tests, rats were pretreated with citalopram (1–17 mg/kg), imipramine (1–17 mg/ kg), or reboxetine (1–30 mg/kg) before the training dose of nicotine and placement in a chamber for a 4-min extinction test. At the higher doses, all three antidepressant drugs blocked responding evoked by the nicotine CS and decreased nicotine-induced hyperactivity. When these higher doses of citalopram, imipramine, and reboxetine were tested alone (no nicotine), they decreased chamber activity and/or dipper entries. Nevertheless, all three drugs produced partial or complete blockade of the CS effects of nicotine at doses that produced no effect on dipper entries or chamber entries. This finding suggests that both neurotransmitters play a role in the CS effects of nicotine and that modifications in these systems by antidepressants may be clinically relevant

Diminished conditioned responding to the nicotine stimulus by antidepressant drugs with differing specificity for the serotonin and norepinephrine transporter

People diagnosed with depression also tend to have a co-morbid nicotine addiction. Thus, there is interest in whether medications used to treat depression alter the effects of nicotine. This study assessed whether the antidepressant drugs citalopram, imipramine, and reboxetine, with differing specificity for the serotonin and norepinephrine transporter, altered responding controlled by the conditional stimulus (CS) effects of nicotine. Rats received intermixed 20-min nicotine (0.4 mg base/kg, SC) and saline sessions. On nicotine sessions, rats had intermittent access to sucrose; no sucrose was available on saline sessions. After discrimination performance stabilized and a nicotine generalization curve (0.025–0.4 mg/kg) was established, the antidepressant drugs were assessed. In these tests, rats were pretreated with citalopram (1–17 mg/kg), imipramine (1–17 mg/ kg), or reboxetine (1–30 mg/kg) before the training dose of nicotine and placement in a chamber for a 4-min extinction test. At the higher doses, all three antidepressant drugs blocked responding evoked by the nicotine CS and decreased nicotine-induced hyperactivity. When these higher doses of citalopram, imipramine, and reboxetine were tested alone (no nicotine), they decreased chamber activity and/or dipper entries. Nevertheless, all three drugs produced partial or complete blockade of the CS effects of nicotine at doses that produced no effect on dipper entries or chamber entries. This finding suggests that both neurotransmitters play a role in the CS effects of nicotine and that modifications in these systems by antidepressants may be clinically relevant

Applying a systems perspective to understand the mechanisms of the European School Fruit and Vegetable Scheme

Background For the past two decades, the percentage of European children who consume fruit daily has remained at around 40%, despite numerous school-based policy efforts and interventions. This study aimed to apply a systems approach to provide an integrated perspective of the mechanisms of the European School Fruit and Vegetable Scheme (the Scheme) to understand better how to increase its long-term impact on children’s fruit and vegetable consumption. Methods We developed a causal loop diagram by synthesizing peer-reviewed articles and national government documents related to the Scheme, following the conceptualization steps of system dynamics. The initial causal loop diagrams were then validated in three stages by consulting with experts (two individuals and a group) in school-based fruit and vegetable programmes, children's fruit and vegetable consumption and the Scheme, using disconfirmatory interview guidelines. Results The findings suggest that a central self-reinforcing mechanism through which children socialize during fruit and vegetable consumption is critical in the habituation process. Additionally, the initial increase in children’s fruit and vegetable consumption following the Scheme implementation is due to growth in three self-reinforcing loops related to motivation and capability mechanisms; however, this trend gradually slows and stops due to four balancing feedback loops with alternative goals related to opportunity mechanisms that reach their limits. Conclusions The scheme's design should incorporate activities that align the objectives of the implementers and recipients of the Scheme at all levels. This alignment should provide children with ongoing opportunities to consume fruits and vegetables and strengthen the motivation and capability mechanisms.publishedVersio

Reaching consensus on definitions for food and physical activity policies: experience from the Policy Evaluation Network

Background - An upsurge in policy evaluation research within public health sciences has led to multi-disciplinary research networks like the ‘Policy Evaluation Network’ (PEN). This multi-disciplinary collaboration highlighted the need for consensus on clear, common terminology and definitions to facilitate the multi-disciplinary research. This article outlines the development process of the PEN definitions glossary tool, with a focus on the key domains of policy design, implementation and outcomes as they apply to physical activity, sedentary behaviour and dietary behaviours. Methods - A project specific participatory process was undertaken, involving PEN researchers (n = 48) from seven European countries across various disciplinary backgrounds. All involved researchers were invited to identify and collate definitions that were commonly used in their research field. Terms and definitions were discussed and debated during three online workshops. Subsequently, the definitions were discussed and refined until consensus was reached. Results - Consensus definitions for 93 terms related to the evaluation of policy design, implementation and outcomes are provided. Consensus was reached on a range of terms where the terms were understood and used differently across represented disciplines (e.g. ‘Outcome’ and ‘Impact’). A conceptual ‘Inter-relations in policy-related concepts’ diagram was developed to enable navigation through an online database with key terms. Conclusions -The definitions resulting from this participatory process has supported PEN researchers and practitioners across disciplines to reach a shared understanding of different terms related to policy evaluation. Thus, providing a platform for avoiding conflicting use of the same terms in differing contexts over the course of the PEN work programme, facilitating clear and consistent communication, and allowing for clarity within collaborative multi-disciplinary projects and in public-facing messages

Towards a harmonized European surveillance for dietary and physical activity indicators in young and adult populations

Background The Policy Evaluation Network proposes a consolidated approach to measure comparable health indicators across European health surveillance systems to evaluate effectiveness of policy action. Methods In a stepwise approach, questionnaire items used by the systems for measuring diet and physical activity data to describe health indicators were identified based on their validity, reliability, and suitability to monitor achievement of health recommendations. They were collated to unified questionnaire modules and discussed bilaterally with representatives of these systems to explore barriers and facilitators for implementation. Also, establishment of a methodological competence platform was proposed, in which the surveillance and monitoring systems agree on the priorities and common quality standards for the harmonization process and to coordinate the integration of questionnaire modules into existing systems. Results In total, seven questionnaire modules were developed, of which two diet and two physical activity modules were proposed for implementation. Each module allows measurement of data reflecting only partial aspects of national and WHO recommendations related to diet and physical activity. Main barriers were the requirements of systems to monitor temporal trends and to minimize costs. Main facilitator for implementation was the systems’ use of questionnaire items that were comparable to the unified modules. Representatives agreed to participate in a methodological competence platform. Conclusion We successfully took first steps in the realization of the roadmap towards a harmonization of European surveillance by introducing unified questionnaire modules allowing the collection of comparable health indicators and by initiating the establishment of a competence platform to guide this process

Applying a systems perspective to understand the mechanisms of the European School Fruit and Vegetable Scheme

BACKGROUND: For the past two decades, the percentage of European children who consume fruit daily has remained at around 40%, despite numerous school-based policy efforts and interventions. This study aimed to apply a systems approach to provide an integrated perspective of the mechanisms of the European School Fruit and Vegetable Scheme (the Scheme) to understand better how to increase its long-term impact on children's fruit and vegetable consumption. METHODS: We developed a causal loop diagram by synthesizing peer-reviewed articles and national government documents related to the Scheme, following the conceptualization steps of system dynamics. The initial causal loop diagrams were then validated in three stages by consulting with experts (two individuals and a group) in school-based fruit and vegetable programmes, children's fruit and vegetable consumption and the Scheme, using disconfirmatory interview guidelines. RESULTS: The findings suggest that a central self-reinforcing mechanism through which children socialize during fruit and vegetable consumption is critical in the habituation process. Additionally, the initial increase in children's fruit and vegetable consumption following the Scheme implementation is due to growth in three self-reinforcing loops related to motivation and capability mechanisms; however, this trend gradually slows and stops due to four balancing feedback loops with alternative goals related to opportunity mechanisms that reach their limits. CONCLUSIONS: The scheme's design should incorporate activities that align the objectives of the implementers and recipients of the Scheme at all levels. This alignment should provide children with ongoing opportunities to consume fruits and vegetables and strengthen the motivation and capability mechanisms