Unfiltered Recordings Research Articles

Initial Design and Testing of Multiplayer Cooperative Game to Support Physical Activity in Schools

Recent studies have shown that children are not adequately physically active and there is a need to increase children’s physical activity. This study describes new opportunities and solutions for using existing games and gamification to increase physical activity among children in Sweden. We adopted the principles of Tic-Tac-Training to redesign, build, and test a classical multiplayer cooperative game, Battleship, to create a PA game that children experience as fun and engaging. The low fidelity prototype of the game was developed using an iterative game development life cycle and tested with 13 young male children aged 8–11 in a real-world informal setting. A mixed-method research approach was used to understand the users’ experiences and the impact of the Battleship-PA game on behavior change regarding physical activity. Research data were collected through audio recordings of interactions, direct observation, and a user experience questionnaire. The results of this study indicate both positive and negative feedback that can be used to improve the game and user experiences. The results from the unfiltered recordings revealed that both teams were competitive, cooperated within their team, and became excited whenever they destroyed opponent’s ships or were close to winning. However, the children felt bored and exhausted when many gamification tasks were repeated several times in a game session. Direct observation indicated that the children enjoyed the physical activities resulting from playing the game. However, participants who had not previously played the classical version of Battleship were confused about the objectives and concept of the game. The analysis of the user experience questionnaire indicated that most children found the game easy to play, motivating, engaging, interactive, fun, cooperative, competitive, and visually appealing. Furthermore, most children agreed that the game helped them to be physically active and strongly agreed that they enjoyed performing the physical activities in the game. Future work is needed to improve the game user interface, gamification elements, and prepare additional physical activity tasks for a rewarding experience.

Multi-Index Ecoacoustics Analysis for Terrestrial Soundscapes: A New Semi-Automated Approach Using Time-Series Motif Discovery and Random Forest Classification

High rates of biodiversity loss caused by human-induced changes in the environment require new methods for large scale fauna monitoring and data analysis. While ecoacoustic monitoring is increasingly being used and shows promise, analysis and interpretation of the big data produced remains a challenge. Computer-generated acoustic indices potentially provide a biologically meaningful summary of sound, however, temporal autocorrelation, difficulties in statistical analysis of multi-index data and lack of consistency or transferability in different terrestrial environments have hindered the application of those indices in different contexts. To address these issues we investigate the use of time-series motif discovery and random forest classification of multi-indices through two case studies. We use a semi-automated workflow combining time-series motif discovery and random forest classification of multi-index (acoustic complexity, temporal entropy, and events per second) data to categorize sounds in unfiltered recordings according to the main source of sound present (birds, insects, geophony). Our approach showed more than 70% accuracy in label assignment in both datasets. The categories assigned were broad, but we believe this is a great improvement on traditional single index analysis of environmental recordings as we can now give ecological meaning to recordings in a semi-automated way that does not require expert knowledge and manual validation is only necessary for a small subset of the data. Furthermore, temporal autocorrelation, which is largely ignored by researchers, has been effectively eliminated through the time-series motif discovery technique applied here for the first time to ecoacoustic data. We expect that our approach will greatly assist researchers in the future as it will allow large datasets to be rapidly processed and labeled, enabling the screening of recordings for undesired sounds, such as wind, or target biophony (insects and birds) for biodiversity monitoring or bioacoustics research.

Perception of a virtual violin radiation in a wave field synthesis system

A method to synthesize the sound radiation characteristics of musical instruments in a wave front synthesis system is proposed and tested. Radiation patterns of a violin are measured with a circular microphone array which consists of 128 pressure receivers. For each critical frequency band one exemplary radiation pattern is decomposed to circular harmonics of order 0 to 64. So the radiation characteristic of the violin is represented by 25 complex radiation patterns. On the reproduction side, these circular harmonics are approximated by 128 densely spaced monopoles by means of 128 broadband impulses. An anechoic violin recording is convolved with these impulses, yielding 128 filtered versions of the recording. These are then synthesized as 128 monopole sources in a wave front synthesis system and compared to a virtual monopole playing the unfiltered recording. The subjects perceive the tone color of the recreated virtual violin as being dependent on the listening position and report that the two source ty...

Saccade detection using a particle filter.

When healthy subjects track a moving target, "catch-up" saccades are triggered to compensate for the non-perfect tracking gain. The evaluation of the pursuit and/or saccade kinematics requires that saccade and pursuit components be separated from the eye movement trace. A similar situation occurs when analyzes eye movements of patients that could contain eye drifts between saccades. This task is especially difficult, because the range of saccadic amplitudes goes from microsaccades (less than 1°) to large exploratory saccades (40°). In this paper we proposed a new algorithm to detect saccades based on a particle filter. The new method suppresses the baseline velocity component linked to smooth pursuit (or to eye drifts) and thus permits a constant threshold during a trial despite the smooth pursuit behavior. It also accounts for a wide range of saccade amplitudes. The new method is validated with five different paradigms, microsaccades, microsaccades plus saccades with drift, linear target motion, non-linear target motion and free viewing. The sensitivity of the method to signal noise is analyzed. Traditional saccade detection algorithms using a velocity (or acceleration or jerk) threshold can be inadequate because of the baseline velocity component linked to the smooth pursuit (especially if the target motion is non-linear, i.e. not constant velocity) or to eye drifts between saccades. The new method detects saccades in challenging situations involving eye movements between saccades (smooth pursuit and/or eye drifts) and unfiltered recordings.

A Single Dose of Neuron-Binding Human Monoclonal Antibody Improves Spontaneous Activity in a Murine Model of Demyelination

Our laboratory demonstrated that a natural human serum antibody, sHIgM12, binds to neurons in vitro and promotes neurite outgrowth. We generated a recombinant form, rHIgM12, with identical properties. Intracerebral infection with Theiler's Murine Encephalomyelitis Virus (TMEV) of susceptible mouse strains results in chronic demyelinating disease with progressive axonal loss and neurologic dysfunction similar to progressive forms of multiple sclerosis. To study the effects of rHIgM12 on the motor function of TMEV-infected mice, we monitored spontaneous nocturnal activity over many weeks. Nocturnal behavior is a sensitive measure of rodent neurologic function because maximal activity changes are expected to occur during the normally active night time monitoring period. Mice were placed in activity boxes eight days prior to treatment to collect baseline spontaneous activity. After treatment, activity in each group was continuously recorded over 8 weeks. We chose a long 8-week monitoring period for two reasons: (1) we previously demonstrated that IgM induced remyelination is present by 5 weeks post treatment, and (2) TMEV-induced demyelinating disease in this strain progresses very slowly. Due to the long observation periods and large data sets, differences among treatment groups may be difficult to appreciate studying the original unfiltered recordings. To clearly delineate changes in the highly fluctuating original data we applied three different methods: (1) binning, (2) application of Gaussian low-pass filters (GF) and (3) polynomial fitting. Using each of the three methods we showed that compared to control IgM and saline, early treatment with rHIgM12 induced improvement in both horizontal and vertical motor function, whereas later treatment improved only horizontal activity. rHIgM12 did not alter activity of normal, uninfected mice. This study supports the hypothesis that treatment with a neuron-binding IgM not only protects neurons in vitro, but also influences functional motor improvement.

Location and Magnitude Estimation of the 9 October 2006 Korean Nuclear Explosion Using the Southern Great Basin Digital Seismic Network as a Large-Aperture Array

The Southern Great Basin Digital Seismic Network (SGBDSN) has been designed for monitoring high-frequency (1–40-Hz) local events at and near Yucca Mountain, Nevada, the designated site for the national high-level nuclear-waste repository. We find that the network is also effective as a large-aperture teleseismic array for monitoring events in and close to North Korea, the recent location of an underground nuclear test that occurred on 9 October 2006, 01:35:28 coordinated universal time (UTC), National Earthquake Information Center (NEIC) m b 4.3. We explain this by (1) low ambient noise, (2) energy-efficient propagation paths (the nuclear explosion and deep earthquakes on nearly the same ray path show dominant frequencies between 0.9 and 2.5 Hz), and (3) coherent signals across the SGBDSN. The network, when used as an array, provides a particularly good beam signal-to-noise ratio (SNR) for the nuclear explosion. Estimated beam SNR is 20 dB at frequencies between 0.9–2.5 Hz. Between January 1996 and December 2006, 58% (11 of 19) of the events with 7.1> m b>3.3 located within 300 km of the North Korean nuclear explosion by NEIC are considered large enough to be confidently picked by an SGBDSN analyst. The first-arrival of the North Korean event itself is apparent on 25 of the 29 SGBDSN unfiltered recordings. The direct P phase is confidently identified using slowness and back azimuth estimated with cross-correlation and frequency-wavenumber methods. Static time corrections for beamforming are estimated using 11 deep earthquakes within 300 km of the nuclear explosion. With the statistical regression model named two-way layout, we estimate the event first-arrival time offset and the mean station effects. The resulting relative time delays are used to calibrate the nuclear explosion single-array location to the NEIC location, using the delays derived from 11 earthquakes. With magnitude substituted for time, the same method is used to estimate magnitude corrections. The SGBDSN magnitude estimate is 4.3 using the Veith–Clawson body-wave magnitude formula.

Abnormal Waveform of the Human Pattern VEP: Contribution from Gamma Oscillatory Components

Stimulus-related oscillatory activity above approximately 20 Hz (gamma band) is observed in the firing rate and membrane or field potentials of neurons in the visual cortex of cat and monkey. Cortical mass responses in the same frequency range are evoked in humans by contrast stimulation and proved (partly) independent of conventional VEPs. Visual evoked responses (pattern VEPs) with abnormal waveform (quasi-sinusoidal or with bifid wave P100) are reportedly common in diseases affecting the visual pathways (e.g., multiple sclerosis). Contributions of gamma activity to the distorted VEP waveform are possible if the mechanisms of generation are differentially affected by brain disorders. This hypothesis was investigated in patients with documented impairment of the visual system. VEPs and oscillatory responses to contrast stimulation (central 9 degrees of visual field; 1.3 to 5.0 cyc/deg; 80% contrast; reversal at 2.13 Hz) were recorded in 765 patients referred for standard visual testing and frequency analyzed. Controls were 40 healthy volunteers. The stimulus conditions and recording procedures replicated previous normative studies on the human oscillatory response. Conventional VEPs were replaced by oscillatory responses comparable to those of controls in the unfiltered recordings of 9.8% of examined patients (with postchiasmatic disorders in 59.9% of cases). Signal amplitude in the frequency interval of the VEPs (below approximately 19 Hz) was significantly lower in the frequency spectra of patients than of controls but did not differ in the frequency range above 20 Hz, reflecting the oscillatory response. The human gamma oscillatory response mediating in cortical visual information processing further proved independent of the VEPs. It can contribute to VEP waveform distortion, and its observation in substitution of VEPs should be regarded as an indication of impaired visual pathway function.

Single-station decomposition of seismograms for subevent time histories

We have adapted an iterative least-squares inversion with positivity constraints to the problem of deconvolving the recordings of a small earthquake from the recordings of a large composite earthquake. The inversion uses an F test to minimize the number of non-zero amplitudes or subevents in the solution set, by requiring each added subevent to reduce the variance significantly. We apply this inversion to the analysis of strong motion recordings of a set of moderate-sized (4.0 ≤ ML ≤ 6.4) aftershocks of the 1976 Friuli earthquake. The earthquake pairs are selected by comparing S trigger times and polarization diagrams. The deconvolved time series are interpreted as the time history of slip events or stress release in the composite earthquake, depending on whether the recordings of the small earthquake are unfiltered or filtered to simulate the waveforms radiated by subevents. Deconvolving with the filtered recordings reduces the variance more rapidly, as a function of the number of subevents, than deconvolving with the unfiltered recordings. The deconvolved time series for three of the four earthquakes analysed indicate that the rupture processes resemble the failure of asperities where the initial subevent has the largest stress drop and the later subevents have longer durations and weaker stress drops.