Comparison of IMU Measurements of Curling Stone Dynamics with a Numerical Model

Abstract Despite almost a century of research, the question of what causes a curling stone to curl (move perpendicular to its initial direction of motion) has no complete answer. Many hypotheses have been formulated, but none has been able to account quantitatively for the full magnitude of the observed curl. The objective of this research was to equip a curling stone with an inertial measurement unit (IMU) and measure its motion, in order to verify a previously published, numerical model of curling stone dynamics. Low cost, small size, accuracy, ease of programming and operation, wireless data communication, and a data-sampling rate near 1 kHz, were selection criteria and constraints for the instrument package. We used the MicroStrain 3DM-GX4-25 system. This is a MEMS-based IMU with a tri-axial gyroscope and a tri-axial linear accelerometer. It was mounted and interfaced with a Bluetooth transmitter, on a curling stone handle. The data were streamed to a host laptop and displayed graphically in real time. Post-processing of the data included filtering and time-integration in order to obtain linear and angular velocities, and displacements. We have compared our experimental results with trajectory data calculated using a previously published numerical model, based on a thermodynamic approach to ice friction. While the observed longitudinal and angular motions are captured reasonably well by the model (errors of about 5% or less), no curl is predicted by the model

Women at risk for sexually transmitted diseases: correlates of intercourse without barrier contraception

Objective: The purpose of this study was to evaluate the correlates of vaginal intercourse without barrier contraception (unprotected intercourse). Study Design: Baseline data from a randomized trial were analyzed to evaluate factors that are associated with intercourse without barrier method use among women \u3c35 years old. Logistic regression models provided estimates of the association of demographic, reproductive, and sexual history variables with unprotected intercourse. Results: Intercourse without barrier contraception was common; 65% of participants had ≥2 episodes of intercourse without barrier contraception use in the past month. Factors that were associated with increased odds of unprotected intercourse included the number of coital episodes, a male partner’s unwillingness to use condoms (adjusted odds ratio, 4.1; 95% CI, 2.3-6.9), and, among women \u3c20 years old, low condom use self-efficacy score (adjusted odds ratio, 1.6; 95% CI, 1.0-2.9). Conclusion: Risk factors for unprotected intercourse included coital frequency and the male partner’s unwillingness to use condoms. Self-efficacy for condom use was especially important for women \u3c20 years old

Measurement of Analyzing Power for Proton-Carbon Elastic Scattering in the Coulomb-Nuclear Interference Region with a 22-GeV/c Polarized Proton Beam

The analyzing power for proton-carbon elastic scattering in the coulomb-nuclear interference region of momentum transfer, $9.0\times10^{-3}<-t<4.1\times10^{-2}$ (GeV/$c)^{2}$, was measured with a 21.7 GeV/$c$ polarized proton beam at the Alternating Gradient Synchrotron of Brookhaven National Laboratory. The ratio of hadronic spin-flip to non-flip amplitude, $r_5$, was obtained from the analyzing power to be $\text{Re} r_5=0.088\pm 0.058$ and $\text{Im} r_5=-0.161\pm 0.226$.Comment: 4 pages, 4 figures and 1 table. Accepted by Physical Review Letter

Cooler Experiment Preparation

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Tailored intervention to increase dual-contraceptive method use: a randomized trial to reduce unintended pregnancies and sexually transmitted infections

Objective: The objective of the study was to determine whether a transtheoretical model–tailored expert system intervention increases dual-method contraceptive use, compared with a nontailored educational intervention. Study Design: We performed a randomized clinical trial of 542 women at high risk for sexually transmitted infections (STIs) and unintended pregnancy. The intervention group received computer-based tailored feedback using a multimedia program. The control group received general contraceptive information and nontailored advice. Results: Participants in the intervention group were more likely to report use of dual contraceptive methods during follow-up (adjusted hazard rate ratio 1.70, 95% confidence interval 1.09, 2.66), compared with controls. However, there were no differences in the rates of incident STI or unintended pregnancy between the 2 groups. Conclusions: The computer-based transtheoretical model–tailored intervention resulted in a 70% increase in reported dual-method contraceptive use in a group of women at high risk for STIs and unintended pregnancy. Inconsistent use of dual methods may explain the lack of effect on unintended pregnancy rates and incident STIs

Possible Observation of the 1/2+ [880] Orbital in 249-Cm

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

User-centred design of flexible hypermedia for a mobile guide: Reflections on the hyperaudio experience

A user-centred design approach involves end-users from the very beginning. Considering users at the early stages compels designers to think in terms of utility and usability and helps develop the system on what is actually needed. This paper discusses the case of HyperAudio, a context-sensitive adaptive and mobile guide to museums developed in the late 90s. User requirements were collected via a survey to understand visitors’ profiles and visit styles in Natural Science museums. The knowledge acquired supported the specification of system requirements, helping defining user model, data structure and adaptive behaviour of the system. User requirements guided the design decisions on what could be implemented by using simple adaptable triggers and what instead needed more sophisticated adaptive techniques, a fundamental choice when all the computation must be done on a PDA. Graphical and interactive environments for developing and testing complex adaptive systems are discussed as a further step towards an iterative design that considers the user interaction a central point. The paper discusses how such an environment allows designers and developers to experiment with different system’s behaviours and to widely test it under realistic conditions by simulation of the actual context evolving over time. The understanding gained in HyperAudio is then considered in the perspective of the developments that followed that first experience: our findings seem still valid despite the passed time

Cooler Target Development

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Cooler Experiment Preparation

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Reconstruction of one-dimensional chaotic maps from sequences of probability density functions

In many practical situations, it is impossible to measure the individual trajectories generated by an unknown chaotic system, but we can observe the evolution of probability density functions generated by such a system. The paper proposes for the first time a matrix-based approach to solve the generalized inverse Frobenius–Perron problem, that is, to reconstruct an unknown one-dimensional chaotic transformation, based on a temporal sequence of probability density functions generated by the transformation. Numerical examples are used to demonstrate the applicability of the proposed approach and evaluate its robustness with respect to constantly applied stochastic perturbations