Fast magnetic resonance elastography with multiphase radial encoding and harmonic motion sparsity based reconstruction

Objective: To achieve fast magnetic resonance elastography (MRE) at a low frequency for better shear modulus estimation of the brain. Approach: We proposed a multiphase radial DENSE MRE (MRD-MRE) sequence and an improved GRASP algorithm utilizing the sparsity of the harmonic motion (SH-GRASP) for fast MRE at 20 Hz. For the MRD-MRE sequence, the initial position encoded by one spatial modulation of magnetization (SPAMM) was decoded by an arbitrary number of readout blocks without increasing the number of phase offsets. Based on the harmonic motion, a modified total variation and temporal Fourier transform were introduced to utilize the sparsity in the temporal domain. Both phantom and brain experiments were carried out and compared with that from multiphase Cartesian DENSE-MRE (MCD-MRE), and conventional gradient echo sequence (GRE-MRE). Reconstruction performance was also compared with GRASP and compressed sensing. Main results: Results showed the scanning time of a fully sampled image with four phase offsets for MRD-MRE was only 1/5 of that from GRE-MRE. The wave patterns and estimated stiffness maps were similar to those from MCD-MRE and GRE-MRE. With SH-GRASP, the total scan time could be shortened by additional 4 folds, achieving a total acceleration factor of 20. Better metric values were also obtained using SH-GRASP for reconstruction compared with other algorithms. Significance: The MRD-MRE sequence and SH-GRASP algorithm can be used either in combination or independently to accelerate MRE, showing the potentials for imaging the brain as well as other organs.

Cultivating science process skills among physics students using PhET simulation in teaching

This paper concerns with the use of simulation as a pedagogical tool for a physics teaching strategy. This action research was conducted to investigate the scientific skills as a result of modelling learnt using PhET simulation. The cycle of action research involved in this study is planning, acting, observing and reflection. Through combining physics simulation with Science Process Skills (SPS) and Manipulative Skills (MS) to deliver real experimenting experience, the discussion is further to make connection with students’ achievement in Physics. One physics class involved in this study consist of 36 matriculation college students. Prior the study, students were briefed on the procedures for conducting the Harmonic Motion experiment using the PhET Simulations. Following this, students must completed the practical report for analysis, data interpretation and discussion. At the end of the teaching, a set of formative test was used to evaluate students’ mastery of Physics concepts after conducting the Simple Harmonic Motion simulation experiment. The results showed an increase in the percentage of frequency of study participants practicing Science Process Skills and Manipulative Skills (Conducting Experiments). In the Formative Test, the study participants showed a high average score of 13.9 marks, which is 93%. This study is able to develop the advantage of multimedia for physics laboratory works and explore its potential to strengthen scientific skills.

Simple Harmonic Motion Electronic Teaching Materials Based on Authentic Learning to Train Students’ Problem-Solving Skills: Aspects of Validity

The absence of teaching materials that can train students’ problem-solving skills optimally is the background of this research. This study describes the validity of simple harmonic motion electronic teaching materials based on authentic learning to train students’ problem-solving skills. This research is development research with the ASSURE model that focuses on the Utilization of Instructional Materials stage. The instrument used is the validity sheet of electronic teaching materials. The validity of electronic teaching materials is viewed from the aspect of content, construct, and appearance. The validation of electronic teaching materials is carried out by three validators: two expert validators and one practitioner validator. The data analysis technique used descriptive statistics. The results showed that the validity of electronic teaching materials with an average score of 3.87 was categorized as good. It was concluded that the simple harmonic motion electronic teaching material based on authentic learning was declared valid to train students’ problem-solving skills. Furthermore, these electronic teaching materials can be used as teaching materials in the classroom to determine the practicality and effectiveness of the developed teaching materials.

Object of learning in the teaching of simple harmonic motion: a case study using active methodology (ISLE type)

In classroom, the Simple Harmonic Movement (SHM) is a content generally seen only in the form of expository classes and, for this reason, considered difficult to understand. In order to solve this problem, the following research question was asked: does the Learning Object (LO) contribute to the understanding of SHM, based on the ISLE Methodology approach? For that, simulations of SMH graphics were created with the aid of digital tools. This research was carried out at IFCE Campus Fortaleza and its main objective was to analyze the use of a LO in the discipline of Physics, aiming to assist the student in the simulation of graphs of the Simple Harmonic Movement (SHM), supported by the Active Methodology of the ISLE type, which proposes a Science Investigative Learning Environment. The students performed a pre-test in which they were to analyze and interpret the data of an SHM from its graph. Then, using the LO, the students explored the variables present in a periodic movement, being able to interact with it and visualizing the changes in the movement and in the graphs related to it. Finally, the students performed a post-test that consisted of, again, interpreting an SHM phenomenon based on its graph and producing new graphs representing other of its variables. The results point to an improvement in the understanding of the learners regarding the studied subject, indicating that the use of digital tools and active methodologies can contribute to a meaningful learning of Physics concepts, more specifically, of the SHM.

PARAMETER ESTIMATION FOR OSCILLATORY SYSTEMS

Simple harmonic motion was investigated of a rotational oscillating system. The effect of dumping and forcing on motion of the system was examined and measurements were taken. Resonance in a oscillating system was investigated and quality factor of the dumping system was measured at different damping forces using three different methods. Resonance curves were constructed at two different damping forces. A probabilistic model was built and system parameters were estimated from the resonance curves using Stan sampling platform. The quality factor of the oscillating system when the additional dumping was turned off was estimated to be $Q = \num{71 \pm 1}$ and natural frequency $\omega_0 = \num{3.105 \pm 0.008}\, \si{\per\second}$.