Observing errors in a combination of error and correct models favors observational motor learning

Background Imitative learning is highly effective from infancy to old age; however, little is known about the effects of observing errors during imitative learning. This study aimed to examine how observing errors affected imitative learning performance to maximize its effect. Methods In the pre-training session, participants were instructed to pinch at a target force (8 N) with auditory feedback regarding generated force while they watched videos of someone pinching a sponge at the target force. In the pre-test, participants pinched at the target force and did not view a model or receive auditory feedback. In Experiment 1, in the main training session, participants imitated models while they watched videos of pinching at either the incorrect force (error-mixed condition) or target force (correct condition). Then, the exact force generated was measured without receiving auditory feedback or viewing a model. In Experiment 2, using the same procedures, newly recruited participants watched videos of pinching at incorrect forces (4 and 24 N) as the error condition and the correct force as the correct condition. Results In Experiment 1, the average force was closer to the target force in the error-mixed condition than in the correct condition. In Experiment 2, the average force in the correct condition was closer to the target force than in the error condition. Conclusion Our findings indicated that observing error actions combined with correct actions affected imitation motor learning positively as error actions contained information on things to avoid in the target action. It provides further information to enhance imitative learning in mixed conditions compared to that with correct action alone.

Unique stochastic Lagrangian particle dispersion models for inhomogeneous turbulent flows

It is well established that Lagrangian particle dispersion models, for inhomogeneous turbulent flows, must satisfy the ‘well-mixed condition’ of Thomson (J. Fluid Mech., vol. 180, 1987, pp. 529–556) in order to produce physically reasonable results. In more than one dimension, however, the well-mixed condition is not sufficient to define the dispersion model uniquely. The non-uniqueness, which is related to the rotational degrees of freedom of particle trajectories, permits models with trajectory curvatures and velocity autocorrelation functions which are clearly unphysical. A spin condition is therefore introduced to constrain the models. It requires an ensemble of particles with fixed initial position and velocity to have, at short times, expected angular momentum, measured relative to the mean position and velocity of an ensemble of fluid particles with initially random velocity, equal to the relative angular momentum of the mean flow at the ensemble mean location. The resulting unique model is found explicitly for the canonical example of inhomogeneous Gaussian turbulence and is characterised by accelerations which are exponential in the particle velocity. A simpler unique model with a quadratic acceleration is obtained using a weaker version of the spin condition. Unlike previous models, the unique models defined by the spin condition lead to particles having the correct (ensemble mean) angular speed in a turbulent flow in solid-body rotation. The properties of the new models are discussed in the settings of a turbulent channel flow and an idealised turbulent atmospheric boundary-layer flow.

Observing Errors in a Combination of Error and Correct Models Favors Observational Motor Learning

Background:Imitative learning is highly effective from infancy to old age, but little is known about the effects of observing errors during imitative learning. This study aims to examine how observing errors affect imitative learning performance, to maximize the effects of imitative learning. Method：In the pre-training session, participants were instructed to pinch at the target force (8 N) with auditory feedback about generated force while watching videos of someone pinching a sponge at the target force. In the pre-test, participants pinched at the target force without viewing a model or receiving auditory feedback. In Experiment 1, in the main training session, participants imitated models while watching videos of pinching at either the incorrect force (error-mixed condition) or the target force (all-correct condition). Then, the exact force they generated in pinching was measured without receiving auditory feedback or viewing a model. In Experiment 2, using the same procedure in the pre-training and pre-test sessions, newly recruited participants watched pinching at incorrect forces (4 and 24 N) as the all-error condition and the correct force as the correct condition. Results: In Experiment 1, the average force was better in the error-mixed condition than in the correct condition. In Experiment 2, the average force in the correct condition was better than that in the error condition.Conclusion: Our findings indicate that observing error actions combined with correct actions affected imitation motor learning positively, because error actions contain what-not-to-do information about the target action, unlike correct actions, which provide more information to enhance imitative learning.

Dilution-based Evaluation of Airborne Infection Risk - Thorough Expansion of Wells-Riley Model

Evaluation of airborne infection risk with spatial and temporal resolutions is indispensable for the design of proper interventions fighting infectious respiratory diseases (e.g., COVID-19), because the distribution of aerosol contagions is both spatially and temporally non-uniform. However, the well-recognized Wells-Riley model and modified Wells-Riley model (i.e., the rebreathed-fraction model) are limited to the well-mixed condition and unable to evaluate airborne infection risk spatially and temporally, which could result in overestimation or underestimation of airborne infection risk. This study proposes a dilution-based evaluation method for airborne infection risk. The method proposed is benchmarked by the Wells-Riley model and modified Wells-Riley model, which indicates that the method proposed is a thorough expansion of the Wells-Riley model for evaluation of airborne infection risk with both spatial and temporal resolutions. Experiments in a mock hospital ward also demonstrate that the method proposed effectively evaluates the airborne infection risk both spatially and temporally.

Legendre Collocation Method to Solve the Riccati Equations with Functional Arguments

In this study, a method for numerically solving Riccatti type differential equations with functional arguments under the mixed condition is presented. For the method, Legendre polynomials, the solution forms and the required expressions are written in the matrix form and the collocation points are defined. Then, by using the obtained matrix relations and the collocation points, the Riccati problem is reduced to a system of nonlinear algebraic equations. The condition in the problem is written in the matrix form and a new system of the nonlinear algebraic equations is found with the aid of the obtained matrix relation. This system is solved and thus the coefficient matrix is detected. This coefficient matrix is written in the solution form and hence approximate solution is obtained. In addition, by defining the residual function, an error problem is established and approximate solutions which give better numerical results are obtained. To demonstrate that the method is trustworthy and convenient, the presented method and error estimation technique are explicated by numerical examples. Consequently, the numerical results are shown more clearly with the aid of the tables and graphs and also the results are compared with the results of other methods.

SAT-482 Simultaneous Hashimoto/Graves Disease or Prolonged Hashitoxicosis? A Diagnostic Challenge with Therapeutic Implications

Background: Some individuals with Hashimoto’s thyroiditis (HT), characterized by anti-TPO antibodies (Abs), can also have positive TSI Abs in up to 20% of cases, without necessarily having Graves disease (GD). Patients with signs of both hyper-and-hypothyroidism with positivity to these two Abs can pose a diagnostic and therapeutic dilemma, as their course is often unpredictable. Clinical Case: A 49-year-old woman was diagnosed with hypothyroidism and took levothyroxine (LT4) for about 1 year, after which she developed symptoms of hyperthyroidism and was switched to methimazole (MMI), which she only took for 1 year. At her initial visit at our clinic she had been off of MMI for 12 months and she was biochemically hyperthyroid (TSH of 0.01 mcIU/ml, f-T4 of 2.26 ng/dl). TSI Abs were positive at 461, but she also tested positive for anti-TPO at 673. Thyroid receptor Abs (TRAb) were also elevated at 54.8. Her vital signs were stable, but she had marked proptosis and complained of eye dryness, so MMI was restarted. A RAIU scan could not be obtained, but a thyroid US showed a heterogeneous and hypervascular gland. On MMI, her thyroid function tests normalized, and her eye disease vastly improved over 2 years. Her MMI dose was progressively decreased until it was stopped completely. On re-evaluation a few months later, she had newly elevated TSH of 8.7 mcIU/ml and low f-T4 of 0.87 ng/dl, with no symptoms of hypothyroidism, so we opted for management with active surveillance instead of starting her on LT4. Her TSI level improved to 240, but remains elevated. Discussion: It is unclear if our patient has a mixed condition with features of both GD and HT, or if she has HT with a very prolonged hyperthyroid phase (hashitoxicosis). Extended periods of hashitoxicosis have been described, the longest reported lasted for 2 years[1]. Simultaneous presentation of GD and HT is very rare, with only a few cases described in the literature. RAIU scan is often diagnostic, showing increased uptake as seen in GD, but patchy areas of decreased uptake can also be seen. In our case it is likely that HT and GD were coexisting, with GD masking the hypothyroidism, until the former remitted with MMI, and her HT took over. Though no RAIU scan was available, the TSI positivity, clinical response of her hyperthyroidism to MMI and the presence of orbitopathy rule in favor of co-existing GD. Decision to treat with LT4 should be weighed against the risk of causing recurrence of hyperthyroidism. Special considerations should be taken in women of childbearing age due to the difficult management that overlapping hyper/hypothyroidism would entail during pregnancy. References: 1. Shahbaz, A et al. Prolonged Duration of Hashitoxicosis in a Patient with Hashimoto’s Thyroiditis: A Case Report and Review of Literature. Cureus. 2018; 10(6):e2804

Isoluminant stimuli in a familiar discrete keying sequence task can be ignored

Motor sequencing models suggest that when with extensive practice sequence representations have developed, stimuli indicating the individual sequence elements may no longer be used for sequence execution. However, it is not clear whether participants can at all refrain from processing these stimuli. Two experiments were performed in which participants practiced two 7-keypress sequences by responding to isoluminant key-specific stimuli. In the mixed condition of the ensuing test phase, the stimuli were displayed only occasionally, and the question was whether this would make participants stop processing these stimuli. In Experiment 1, the benefit of displaying stimuli was assessed after substantial practice, while Experiment 2 examined development of this benefit across practice. The results of Experiment 1 showed that participants rely a little less on these stimuli when they are displayed only occasionally, but Experiment 2 revealed that participants quickly developed high awareness, and that they ignored these stimuli already after limited practice. These findings confirm that participants can choose to ignore these isoluminant stimuli but tend to use them when they are displayed. These and other findings show in some detail how various cognitive systems interact to produce familiar keying sequences.

Effect of Rotating Cylinder on Mixing Performance in a Cylindrical Double-Ribbon Mixer

Uniform mixing is highly essential in the food manufacturing, pharmaceutical, chemical, and cement industries. However, based on the various process requirements, these industries use different mixers to achieve their commercial outputs. Most of these industries rely on sample-based verification of the mixing index, which may not produce accurate results. Adopting a non-sampling mixing index method is more accurate. In this study, we used the discrete element method (DEM) to simulate the mixing of multiple components contained in a typical commercial whey protein mixture. An effective non-sampling mixing index, the subdomain-based mixing index (SMI), was incorporated to assess the mixing levels. The main motivation for this study was to acquire a high mixing index in the least possible mixing time to boost the manufacturing rate. For this purpose, a half-filled cylindrical double ribbon mixer was simulated, and the SMI outputs are presented for the following four cases: (1) rotating ribbon, (2) rotating cylinder, (3) rotating cylinder with a static ribbon, and (4) rotating cylinder and ribbon. For the given simulation conditions, the SMI values ranged from 0 (segregation condition) to 0.91–0.94 (fully randomly mixed condition) within a time range of 0–60 s.