An approach to high speed ship ride quality simulation

The high speeds attained by certain advanced surface ships result in a spectrum of motion which is higher in frequency than that of conventional ships. This fact along with the inclusion of advanced ride control features in the design of these ships resulted in an increased awareness of the need for ride criteria. Such criteria can be developed using data from actual ship operations in varied sea states or from clinical laboratory experiments. A third approach is to simulate ship conditions using measured or calculated ship motion data. Recent simulations have used data derived from a math model of Surface Effect Ship (SES) motion. The model in turn is based on equations of motion which have been refined with data from scale models and SES of up to 101 600-kg (100-ton) displacement. Employment of broad band motion emphasizes the use of the simulators as a design tool to evaluate a given ship configuration in several operational situations and also serves to provide data as to the overall effect of a given motion on crew performance and physiological status

Open-source development experiences in scientific software: the HANDE quantum Monte Carlo project

The HANDE quantum Monte Carlo project offers accessible stochastic algorithms for general use for scientists in the field of quantum chemistry. HANDE is an ambitious and general high-performance code developed by a geographically-dispersed team with a variety of backgrounds in computational science. In the course of preparing a public, open-source release, we have taken this opportunity to step back and look at what we have done and what we hope to do in the future. We pay particular attention to development processes, the approach taken to train students joining the project, and how a flat hierarchical structure aids communicationComment: 6 pages. Submission to WSSSPE

Endogenous fantasy and learning in digital games.

Many people believe that educational games are effective because they motivate children to actively engage in a learning activity as part of playing the game. However, seminal work by Malone (1981), exploring the motivational aspects of digital games, concluded that the educational effectiveness of a digital game depends on the way in which learning content is integrated into the fantasy context of the game. In particular, he claimed that content which is intrinsically related to the fantasy will produce better learning than that which is merely extrinsically related. However, this distinction between intrinsic and extrinsic (or endogenous and exogenous) fantasy is a concept that has developed a confused standing over the following years. This paper will address this confusion by providing a review and critique of the empirical and theoretical foundations of endogenous fantasy, and its relevance to creating educational digital games. Substantial concerns are raised about the empirical basis of this work and a theoretical critique of endogenous fantasy is offered, concluding that endogenous fantasy is a misnomer, in so far as the "integral and continuing relationship" of fantasy cannot be justified as a critical means of improving the effectiveness of educational digital games. An alternative perspective on the intrinsic integration of learning content is described, incorporating game mechanics, flow and representations

Accurate exchange-correlation energies for the warm dense electron gas

Density matrix quantum Monte Carlo (DMQMC) is used to sample exact-on-average $N$-body density matrices for uniform electron gas systems of up to 10$^{124}$ matrix elements via a stochastic solution of the Bloch equation. The results of these calculations resolve a current debate over the accuracy of the data used to parametrize finite-temperature density functionals. Exchange-correlation energies calculated using the real-space restricted path-integral formalism and the $k$-space configuration path-integral formalism disagree by up to $\sim$$10$\% at certain reduced temperatures $T/T_F \le 0.5$ and densities $r_s \le 1$. Our calculations confirm the accuracy of the configuration path-integral Monte Carlo results available at high density and bridge the gap to lower densities, providing trustworthy data in the regime typical of planetary interiors and solids subject to laser irradiation. We demonstrate that DMQMC can calculate free energies directly and present exact free energies for $T/T_F \ge 1$ and $r_s \le 2$.Comment: Accepted version: added free energy data and restructured text. Now includes supplementary materia

A survey on the English FA heading guidelines for youth soccer: Evidence of compliance, but with limited knowledge of safety

Soccer heading may be problematic for neurocognitive function. The English Football Association (FA) recently introduced guidelines in order to limit the number of headers within training for youth soccer. However, it remains to be seen what the influence of these guidelines has been on the leaders of soccer teams that are primarily responsible for implementing the guidelines. Thus, we aimed to explore grassroot youth coaches’ knowledge of, views on, and adherence to the heading guidelines. An online survey was distributed to team representatives across Local County FAs. The survey comprised of three sections: (1) background information, (2) heading practices including details on heading activities and views on heading safety, and (3) heading guidelines including levels of awareness, knowledge, and compliance. 240 coaches responded by stating they rarely (21%) or never (73%) practiced heading, although they mostly perceived heading as being somewhat safe (36%). While respondents indicated being only somewhat aware of the guidelines (43%), they scored very high on their perceived (92%) and actual (based on retrospective accounts of heading) (87%) compliance with the guidelines. There was a mixed perceived change within practice following the introduction of the guidelines (disagree = 26% vs. agree = 22%), and they were perceived as safe (86%) and appropriate (81%). Factors that were identified as being potential barriers were only marginally agreed upon (<30%) and tended to be related to in-game rules. While there is scope to successfully implement heading guidelines, there is some discrepancy between the requirements for heading safety and coaches’ knowledge

A bayesian nonparametric model for white blood cells in patients with lower urinary tract symptoms

Lower Urinary Tract Symptoms (LUTS) affect a significant proportion of the population and often lead to a reduced quality of life. LUTS overlap across a wide variety of diseases, which makes the diagnostic process extremely complicated. In this work we focus on the relation between LUTS and Urinary Tract Infection (UTI). The latter is detected through the number of White Blood Cells (WBC) in a sample of urine: WBC≥ 1 indicates UTI and high levels may indicate complications. The objective of this work is to provide the clinicians with a tool for supporting the diagnostic process, deepening the available knowledge about LUTS and UTI. We analyze data recording both LUTS profile and WBC count for each patient. We propose to model the WBC using a random partition model in which we specify a prior distribution over the partition of the patients which includes the clustering information contained in the LUTS profile. Then, within each cluster, the WBC counts are assumed to be generated by a zero-inflated Poisson distribution. The results of the predictive distribution allows to identify the symptoms configuration most associated with the presence of UTI as well as with severe infections

The Climate CoLab: Large scale model-based collaborative planning

The Climate CoLab is a system to help thousands of people around the world collectively develop plans for what humans should do about global climate change. This paper shows how the system combines three design elements (model-based planning, on-line debates, and electronic voting) in a synergistic way. The paper also reports early usage experience showing that: (a) the system is attracting a continuing stream of new and returning visitors from all over the world, and (b) the nascent community can use the platform to generate interesting and high quality plans to address climate change. These initial results indicate significant progress towards an important goal in developing a collective intelligence system - the formation of a large and diverse community collectively engaged in solving a single problem.Cisco Systems, Inc.Argosy FoundationMIT Energy InitiativeMIT Sloan Sustainability Initiativ