Detecting the Speed Change Intention from EEG Signals: From the Offline and Pseudo-Online Analysis to an Online Closed-Loop Validation

Control of assistive devices by voluntary user intention is an underdeveloped topic in the Brain–Machine Interfaces (BMI) literature. In this work, a preliminary real-time BMI for the speed control of an exoskeleton is presented. First, an offline analysis for the selection of the intention patterns based on the optimum features and electrodes is proposed. This is carried out comparing three different classification models: monotonous walk vs. increasing and decreasing change speed intentions, monotonous walk vs. only increasing intention, and monotonous walk vs. only decreasing intention. The results indicate that, among the features tested, the most suitable parameter to represent these models are the Hjorth statistics in alpha and beta frequency bands. The average offline classification accuracy for the offline cross-validation of the three models obtained is 68 ± 11%. This selection is also tested following a pseudo-online analysis, simulating a real-time detection of the subject’s intentions to change speed. The average results indices of the three models during this pseudoanalysis are of a 42% true positive ratio and a false positive rate per minute of 9. Finally, in order to check the viability of the approach with an exoskeleton, a case of study is presented. During the experimental session, the pros and cons of the implementation of a closed-loop control of speed change for the H3 exoskeleton through EEG analysis are commented.

APPLICATION OF THREE-DIMENSIONAL MODELING TO OPTIMIZE THE DIMENTIONS OF THE SPEED CONTROL DEVICE WITH ROTARY STOPPER IN THE FORM OF A CLOSED-LOOP HYDRAULIC SYSTEM

The aim of this work is to create a three-dimensional model of a new speed change control device using an engineering CAD system Solidworks. In particular, the article describes the methods of computer construction of a three-dimensional model of a rotary stopper in the form of a closed-loop hydraulic system of the device for smooth control of speed changes through a gear differential. The control link can be either a ring gear, or a carrier, or a sun gear. Ways of creating new parts of the device, use of elements from standard libraries and coordination of their dimensions in assembly have been considered. The ability to parameterize the dimensions allows you to automate the creation of both a single part and the whole device of a particular design, based on the specified source data. The application of special meshes for modeling movable and fixed joints allows you to correctly place the parts, control the correctness of their assembly, and then conduct kinematic and power studies of the device, animate its elements in motion. It has been concluded that the use of computer three-dimensional modeling in the design of such stoppers allows: at the initial stage of design to get a visual idea of the stopper of rotational motion; use a computer to view the created model from any point; easy to edit three-dimensional models, i.e. make the necessary changes; achieve great savings in time and design costs; get a large number of possible design solutions that need to be analyzed in detail and in depth to choose the rational, i.e. the best fit. The created model of the stopper of rotational movement allows to choose the optimal place of its installation in a gear differential of the device of speed change from the point of view of use of the minimum sizes and volume. Based on this, computer simulation must precede design. Keywords: three-dimensional modeling; rotary stopper; closed-loop hydraulic system; gear differential

Effect of Baseline BMI and IL-6 on Gait Speed Response to Caloric Restriction in Older Adults

We examined whether the effect of caloric restriction (CR) on gait speed change in older adults (67.3±5.27 years) varied by BMI and interleukin 6 (IL-6). Data from eight six-month randomized controlled trials were pooled, with 1268 participants randomized to CR (n=710) and non-CR (n=558) conditions. Baseline BMI/IL-6 subgroups were constructed using BMI≥35 kg/m2 and IL-6>2.5 pg/dL, and participants were jointly classified as high/high (n=395), high/low (n=208), low/high (n=271), or low/low (n=344). Overall treatment effects showed significant improvements in gait speed in CR versus non-CR [mean difference: 0.02 m/s (95% CI: 0.01, 0.04)]; however, CR assignment significantly interacted with BMI/IL-6 subgroup (p=0.03). Greatest gait speed improvement was observed in the high/high CR subgroup [+0.06 m/s (0.03, 0.09)] and appeared to be driven by no gait speed change among the high/high non-CR subgroup. Gait speed response to CR was greatest in older adults with elevated baseline BMI and IL-6.

Novel Positional Candidate Gene for Gait Speed Change in Older Adults: The Long Life Family Study

Gait speed is a heritable, robust predictor of longevity in older adults. Using genome-wide linkage analysis in 2379 individuals from 509 families (64±12 years; 45% men), we identified a locus on chromosome 16p linked to gait speed change over 7±1 years (logarithm of the odds score [LOD]=4.2). Gait speed change was calculated using a two-stage growth curve mixed-model. DNA sequencing was completed to identify single nucleotide variants (SNVs) in the linkage region. Association analyses between the 24039 SNVs in the ~1.6mBP region (3.7-5.3mBP) and gait speed change were performed adjusting for age, age2, sex, height, field center, familial relatedness and population substructure. Eleven families (188 individuals) accounted for most of the linkage signal (LOD=6.06). Associations between SNVs flanking the Mesothelin (MSLN) gene and gait speed change were identified (lead SNV rs56850119: β = -0.5±0.1, p = 6.4*10-7). Thus, MSLN is a potential positional candidate gene for mobility decline with aging.

Effects of Moderate-to-Vigorous Acute Exercise on Visual Consciousness

Background the effect of acute exercise on cognition covers almost all stages of information processing, but few studies have focused on visual awareness. Subjective reports on the appearance of faint speed-changes in the perception of stimuli were used as an index for visual consciousness. Visual consciousness was assessed after exercise or rest. Aside from subjective index, objective speed-change discrimination was added as an index for the level of consciousness. Results: the results showed that subjective reports on the appearance of faint speed-changes in the perception of stimuli were affected by acute aerobic exercise. The hit rate for speed-change detection was marginally significantly higher after exercise than sedentary condition. Furthermore, the d’ index was higher after exercise. Analysis of the results obtained for the objective discrimination task showed that discrimination speed was boosted only when subjects were aware of the speed-change. Conclusions: these results suggest that acute exercise enhances visual consciousness.

Glacier geometry and flow speed determine how Arctic marine-terminating glaciers respond to lubricated beds

Basal conditions directly control the glacier sliding rate and the dynamic discharge of ice flow. Recent glacier destabilization events indicate that some marine-terminating glaciers quickly respond to lubricated beds with increased flow speed, but the underlying physics, especially how this vulnerability relates to glacier geometry and flow characteristics, remains unclear. This paper presents a 1-D physical framework for glacier dynamic vulnerability assuming sudden basal lubrication as an initial perturbation. In this new model, two quantities determine the scale and the areal extent of the subsequent thinning and acceleration after the bed is lubricated: Péclet number (Pe) and the product of glacier speed and thickness gradient (dubbed J0 in this study). To validate the model, this paper calculates Pe and J0 using multi-sourced data from 1996–1998 for outlet glaciers in Greenland and Austfonna Ice Cap, Svalbard, and compares the results with the glacier speed change during 1996/1998–2018. Glaciers with lower Pe and J0 are more likely to accelerate during this 20-year span than those with higher Pe and J0, which matches the model prediction. A combined factor of ice thickness, surface slope, and initial speed for ice flow physically determines how much and how fast glaciers respond to lubricated beds, as forms of speed, elevation, and terminus change.

High Payload Qr-Based Data Hiding Using Secured Compressed Watermark in Polar Domain

Audio Watermarking is a method to insert a copyright marker on audio. This method inserts a watermark in the information form and in a way that does not damage the audio. This technique is one of the ways to solve the problem of copyright infringement. The embedded watermark has to meet the condition of not damaging the audio and must have robustness, imperceptibility, and good capacity. The data hiding technique use the combined method of Lifting Wavelet Transform (LWT), Fast Fourier Transform (FFT), QR Decomposition and Reconstruction, and Cartesian-Polar Transformation (CPT) based on Quantization Index Modulation (QIM) with the secured and compressed watermark using Compressive Sampling (CS) technique. The proposed scheme is blind Audio Watermarking as it no needs for original audio in the detection process. The combination of methods overcomes multiple attacks with guaranteed quality watermarking and high capacity. Compared to the existing technique, the data hiding technique can withstand LPF attacks, Resampling, Linear speed change (LSC), and MP3 compression. This proposed technique is also secured due to the coded watermark by a particular random key using CS. Combining CS and Audio Watermarking techniques can perform well in capacity, imperceptibility, security, and attack resistance.

The Potential to Use Variations in Tree-Ring Geometric Center to Estimate Past Wind Speed Change

Tree radial growth is characterized by not only the annual ring-width increment but also shifts in the tree-ring geometric center (TRGC) if subjected to asymmetric external forcing, such as prevailing winds. Previous dendrochronological studies have used the asymmetric growth derived from tree-ring widths to reconstruct wind speed changes. Here we propose a novel method use quantitative TRGC measurements to estimate wind speed. We investigated TRGC shifts in northeast China, where the prevailing westerly winds are strong and persistent. We found that the TRGC showed significant correlations (r = 0.64, p < 0.01) with wind speed in May-September. The higher tree geometry sensitivity to wind speed obtained with the new method compared to previous ones, suggests the possibility of reconstructing historical wind change and variability in prevailing winds using TRGC. In addition, by correcting tree-ring radius according to their TRGC shifts, the basal area increment (BAI) was calculated. Our new BAI estimation provided stronger correlations with climate than both the standard tree-ring width chronology and a traditional BAI estimation. We suggest that future dendrochronological studies should consider TRGC shifts to increase the accuracy in climate reconstructions.

Adaptive Forest Fire Spread Simulation Algorithm Based on Cellular Automata

The popular simulation process that uses traditional cellular automata with a fixed time step to simulate forest fire spread may be limited in its ability to reflect the characteristics of actual fire development. This study combines cellular automata with an existing forest fire model to construct an improved forest fire spread model, which calculates a speed change rate index based on the meteorological factors that affect the spread of forest fires and the actual environment of the current location of the spread. The proposed model can adaptively adjust the time step of cellular automata through the speed change rate index, simulating forest fire spread more in line with the actual fire development trends while ensuring accuracy. When used to analyze a forest fire that occurred in Mianning County, Liangshan Prefecture, Sichuan Province in 2020, our model exhibited simulation accuracy of 96.9%, and kappa coefficient of 0.6214. The simulated fire situation adapted well to the complex and dynamic fire environment, accurately depicting the detailed fire situation. The algorithm can be used to simulate and predict the spread of forest fires, ensuring the accuracy of spread simulation and helping decision makers formulate reasonable plans.