Estimation of joint torque in dynamic activities using wearable A-mode ultrasound.

The human body constantly experiences mechanical loading. However, quantifying internal loads within the musculoskeletal system remains challenging, especially during unconstrained dynamic activities. Conventional measures are constrained to laboratory settings, and existing wearable approaches lack muscle specificity or validation during dynamic movement. Here, we present a strategy for estimating corresponding joint torque from muscles with different architectures during various dynamic activities using wearable A-mode ultrasound. We first introduce a method to track changes in muscle thickness using single-element ultrasonic transducers. We then estimate elbow and knee torque with errors less than 7.6% and coefficients of determination (R2) greater than 0.92 during controlled isokinetic contractions. Finally, we demonstrate wearable joint torque estimation during dynamic real-world tasks, including weightlifting, cycling, and both treadmill and outdoor locomotion. The capability to assess joint torque during unconstrained real-world activities can provide new insights into muscle function and movement biomechanics, with potential applications in injury prevention and rehabilitation.

The unexpected influence of legacy conspecific density dependence.

When plants die, neighbours escape competition. Living conspecifics could disproportionately benefit because they are freed from negative intraspecific processes; however, if the negative effects of past conspecific neighbours persist, other species might be advantaged, and diversity might be maintained through legacy effects. We examined legacy effects in a mapped forest by modelling the survival of 37,212 trees of 23 species using four neighbourhood properties: living conspecific, living heterospecific, legacy conspecific (dead conspecifics) and legacy heterospecific densities. Legacy conspecific effects proved nearly four times stronger than living conspecific effects; changes in annual survival associated with legacy conspecific density were 1.5% greater than living conspecific effects. Over 90% of species were negatively impacted by legacy conspecific density, compared to 47% by living conspecific density. Our results emphasize that legacies of trees alter community dynamics, revealing that prior research may have underestimated the strength of density dependent interactions by not considering legacy effects.

Wearable robots for the real world need vision.

To enhance wearable robots, understanding user intent and environmental perception with novel vision approaches is needed.

Latitudinal patterns in stabilizing density dependence of forest communities.

Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species1,2, a phenomenon known as conspecific negative density dependence (CNDD)3. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests4,5, which increases community stabilization, species coexistence and the diversity of local tree species6,7. Previous analyses supporting such a latitudinal gradient in CNDD8,9 have suffered from methodological limitations related to the use of static data10-12. Here we present a comprehensive assessment of latitudinal CNDD patterns using dynamic mortality data to estimate species-site-specific CNDD across 23 sites. Averaged across species, we found that stabilizing CNDD was present at all except one site, but that average stabilizing CNDD was not stronger toward the tropics. However, in tropical tree communities, rare and intermediate abundant species experienced stronger stabilizing CNDD than did common species. This pattern was absent in temperate forests, which suggests that CNDD influences species abundances more strongly in tropical forests than it does in temperate ones13. We also found that interspecific variation in CNDD, which might attenuate its stabilizing effect on species diversity14,15, was high but not significantly different across latitudes. Although the consequences of these patterns for latitudinal diversity gradients are difficult to evaluate, we speculate that a more effective regulation of population abundances could translate into greater stabilization of tropical tree communities and thus contribute to the high local diversity of tropical forests.

The Billirud Mill Blastomycosis Outbreak: Comparison to Historical Controls.

A large outbreak of blastomycosis among paper mill workers in Escanaba, Michigan began with the first cases reported on February 28, 2023 and expanded to 120 cases. Analysis of baseline regional data and the data collected during this unprecedented outbreak provide insight on the outbreak's unique characteristics. The Michigan Disease Surveillance System provided descriptive and outcome data on blastomycosis cases in the Upper Peninsula from 2007 through 2022 and the 2023 outbreak. Baseline incidence for the region was estimated and outbreak cases were compared to historic controls using quantitative methods such as t-tests, chi-square, and Poisson and logistic regression. The Billirud blastomycosis outbreak has resulted in 28 confirmed and 92 probable cases. Blastomycosis incidence for the Upper Peninsula was 2.13 (95%CI: 1.75, 2.59) per 100,000 person-years with counties bordering Wisconsin having a higher incidence more than other counties (4.56, 95%CI: 3.48, 5.97; RR=3.46, 95%CI: 2.35, 5.11). Outbreak cases were significantly younger, more likely to be male, reported more respiratory symptoms, and had a shorter time from onset of illness to diagnosis. The Billirud paper mill blastomycosis outbreak is the largest reported to date, the first in an industrial facility, and the first to specifically involve Blastomyces gilchristii. Blastomyces species are endemic in regional forests, so other facilities handling forestry products may be at risk.

The characteristics of the cases from the largest outbreak of blastomycosis in North America are compared to sporadic cases from the same region over the previous 16 years. The outbreak cases were younger, more likely to be male, and reported more respiratory difficulties.

Improved Fascicle Length Estimates From Ultrasound Using a U-net-LSTM Framework.

Brightness-mode (B-mode) ultrasound has been used to measure in vivo muscle dynamics for assistive devices. Estimation of fascicle length from B-mode images has now transitioned from time-consuming manual processes to automatic methods, but these methods fail to reach pixel-wise accuracy across extended locomotion. In this work, we aim to address this challenge by combining a U-net architecture with proven segmentation abilities with an LSTM component that takes advantage of temporal information to improve validation accuracy in the prediction of fascicle lengths. Using 64,849 ultrasound frames of the medial gastrocnemius, we semi-manually generated ground-truth for training the proposed U-net-LSTM. Compared with a traditional U-net and a CNNLSTM configuration, the validation accuracy, mean square error (MSE), and mean absolute error (MAE) of the proposed U-net-LSTM show better performance (91.4%, MSE =0.1± 0.03 mm, MAE =0.2± 0.05 mm). The proposed framework could be used for real-time, closed-loop wearable control during real-world locomotion.

Mycorrhizal feedbacks influence global forest structure and diversity.

One mechanism proposed to explain high species diversity in tropical systems is strong negative conspecific density dependence (CDD), which reduces recruitment of juveniles in proximity to conspecific adult plants. Although evidence shows that plant-specific soil pathogens can drive negative CDD, trees also form key mutualisms with mycorrhizal fungi, which may counteract these effects. Across 43 large-scale forest plots worldwide, we tested whether ectomycorrhizal tree species exhibit weaker negative CDD than arbuscular mycorrhizal tree species. We further tested for conmycorrhizal density dependence (CMDD) to test for benefit from shared mutualists. We found that the strength of CDD varies systematically with mycorrhizal type, with ectomycorrhizal tree species exhibiting higher sapling densities with increasing adult densities than arbuscular mycorrhizal tree species. Moreover, we found evidence of positive CMDD for tree species of both mycorrhizal types. Collectively, these findings indicate that mycorrhizal interactions likely play a foundational role in global forest diversity patterns and structure.

Biogeographic context is related to local scale tree demography, co-occurrence and functional differentiation.

Identifying the drivers of community structure and dynamics is a major pursuit in ecology. Emphasis is typically placed on the importance of local scale interactions when attempting to explain these fundamental ecological patterns. However, regional scale phenomena are also important predictors. The importance of regional scale context should be more evident in assemblages where multiple species are close to their range margins. Here, we test the importance of regional scale context using data from a temperate forest plot that contains two species groups - one near its northern range limit and one near its southern range limit. We show the proximity of species to their southern or northern range margins is linked to local scale co-occurrence, similarity in gene expression responses to a key environmental driver, demographic performance and inter-specific variation in conspecific negative density dependence. In sum, many of the key local scale patterns and processes of interest to community ecologists are linked to biogeographic context that is frequently ignored.

Pure Conducting Polymer Hydrogels Increase Signal-to-Noise of Cutaneous Electrodes by Lowering Skin Interface Impedance.

Cutaneous electrodes are routinely used for noninvasive electrophysiological sensing of signals from the brain, the heart, and the neuromuscular system. These bioelectronic signals propagate as ionic charge from their sources to the skin-electrode interface where they are then sensed as electronic charge by the instrumentation. However, these signals suffer from low signal-to-noise ratio arising from the high impedance at the tissue-to-electrode contact interface. This paper reports that soft conductive polymer hydrogels made purely of poly(3,4-ethylenedioxy-thiophene) doped with poly(styrene sulfonate) present nearly an order of magnitude decrease in the skin-electrode contact impedance (88%, 82%, and 77% at 10, 100, and 1 kHz, respectively) when compared to clinical electrodes in an ex vivo model that isolates the bioelectrochemical features of a single skin-electrode contact. Integrating these pure soft conductive polymer blocks into an adhesive wearable sensor enables high fidelity bioelectronic signals with higher signal-to-noise ratio (average 2.1 dB increase, max 3.4 dB increase) when compared to clinical electrodes across all subjects. The utility of these electrodes is demonstrated in a neural interface application. The conductive polymer hydrogels enable electromyogram-based velocity control of a robotic arm to complete a pick and place task. This work provides a basis for the characterization and use of conductive polymer hydrogels to better couple human and machine.

Age-Related Reliability of B-Mode Analysis for Tailored Exosuit Assistance.

In the field of wearable robotics, assistance needs to be individualized for the user to maximize benefit. Information from muscle fascicles automatically recorded from brightness mode (B-mode) ultrasound has been used to design assistance profiles that are proportional to the estimated muscle force of young individuals. There is also a desire to develop similar strategies for older adults who may have age-altered physiology. This study introduces and validates a ResNet + 2x-LSTM model for extracting fascicle lengths in young and older adults. The labeling was generated in a semimanual manner for young (40,696 frames) and older adults (34,262 frames) depicting B-mode imaging of the medial gastrocnemius. First, the model was trained on young and tested on both young (R2 = 0.85, RMSE = 2.36 ± 1.51 mm, MAPE = 3.6%, aaDF = 0.48 ± 1.1 mm) and older adults (R2 = 0.53, RMSE = 4.7 ± 2.51 mm, MAPE = 5.19%, aaDF = 1.9 ± 1.39 mm). Then, the performances were trained across all ages (R2 = 0.79, RMSE = 3.95 ± 2.51 mm, MAPE = 4.5%, aaDF = 0.67 ± 1.8 mm). Although age-related muscle loss affects the error of the tracking methodology compared to the young population, the absolute percentage error for individual fascicles leads to a small variation of 3-5%, suggesting that the error may be acceptable in the generation of assistive force profiles.

Gaussian process regression for ultrasound scanline interpolation.

Purpose: In ultrasound imaging, interpolation is a key step in converting scanline data to brightness-mode (B-mode) images. Conventional methods, such as bilinear interpolation, do not fully capture the spatial dependence between data points, which leads to deviations from the underlying probability distribution at the interpolation points. Approach: We propose Gaussian process ( GP ) regression as an improved method for ultrasound scanline interpolation. Using ultrasound scanlines acquired from two different ultrasound scanners during in vivo trials, we compare the scanline conversion accuracy of three standard interpolation methods with that of GP regression, measuring the peak signal-to-noise ratio (PSNR) and mean absolute error (MAE) for each method. Results: The PSNR and MAE scores show that GP regression leads to more accurate scanline conversion compared to the nearest neighbor, bilinear, and cubic spline interpolation methods, for both datasets. Furthermore, limiting the interpolation window size of GP regression to 15 reduces computation time with minimal to no reduction in PSNR. Conclusions: GP regression quantitatively leads to more accurate scanline conversion and provides uncertainty estimates at each of the interpolation points. Our windowing method reduces the computational cost of using GP regression for scanline conversion.

Distribution of biomass dynamics in relation to tree size in forests across the world.

Tree size shapes forest carbon dynamics and determines how trees interact with their environment, including a changing climate. Here, we conduct the first global analysis of among-site differences in how aboveground biomass stocks and fluxes are distributed with tree size. We analyzed repeat tree censuses from 25 large-scale (4-52 ha) forest plots spanning a broad climatic range over five continents to characterize how aboveground biomass, woody productivity, and woody mortality vary with tree diameter. We examined how the median, dispersion, and skewness of these size-related distributions vary with mean annual temperature and precipitation. In warmer forests, aboveground biomass, woody productivity, and woody mortality were more broadly distributed with respect to tree size. In warmer and wetter forests, aboveground biomass and woody productivity were more right skewed, with a long tail towards large trees. Small trees (1-10 cm diameter) contributed more to productivity and mortality than to biomass, highlighting the importance of including these trees in analyses of forest dynamics. Our findings provide an improved characterization of climate-driven forest differences in the size structure of aboveground biomass and dynamics of that biomass, as well as refined benchmarks for capturing climate influences in vegetation demographic models.

Consequences of spatial patterns for coexistence in species-rich plant communities.

Ecology cannot yet fully explain why so many tree species coexist in natural communities such as tropical forests. A major difficulty is linking individual-level processes to community dynamics. We propose a combination of tree spatial data, spatial statistics and dynamical theory to reveal the relationship between spatial patterns and population-level interaction coefficients and their consequences for multispecies dynamics and coexistence. Here we show that the emerging population-level interaction coefficients have, for a broad range of circumstances, a simpler structure than their individual-level counterparts, which allows for an analytical treatment of equilibrium and stability conditions. Mechanisms such as animal seed dispersal, which result in clustering of recruits that is decoupled from parent locations, lead to a rare-species advantage and coexistence of otherwise neutral competitors. Linking spatial statistics with theories of community dynamics offers new avenues for explaining species coexistence and calls for rethinking community ecology through a spatial lens.

Acupressure for labor pain management: a systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: To evaluate the efficacy/effectiveness of acupressure as an adjunct to standard procedures during labor and delivery, compared with standard procedures with/without sham acupressure, in randomized controlled trials (RCTs). METHODS: Ten main databases were searched from their inception until 31 January 2018. Two reviewers independently extracted data concerning the effects of acupressure on pain intensity, labor duration, mode of delivery, use of medications and adverse events. A meta-analysis of these measures was performed using RevMan 5.3. Pooled standardized mean differences (SMDs) or odds ratios (ORs) for the above outcomes were estimated with a fixed or random effects model, according to the heterogeneity. RESULTS: A total of 13 RCTs including 1586 enrolled patients met the eligibility criteria. Acupressure plus standard procedures (ASP) for labor management significantly reduced pain sensation, compared with sham acupressure plus standard procedures (SASP) and standard procedures (SP) alone. The analgesic effect of acupressure was immediate and persisted for at least 60 min (all p < 0.01). Compared with the untreated control groups, the acupressure group had a shorter duration of labor, especially the first stage of labor (SMD = -0.76, 95% confidence interval (CI) = -1.10 to -0.43; p < 0.001; I2 = 74%) and second stage of labor (SMD = -0.37, 95% CI = -0.59 to -0.18; p < 0.001; I2 = 0%). Data suggesting that acupressure reduced the Cesarean section rate was inconclusive. The use of pharmacologic agents (oxytocin and analgesics) did not differ between the ASP, SASP and SP groups. No adverse events were reported in this limited number of studies. CONCLUSION: Moderate evidence indicates that acupressure may have promising effects on labor pain and duration. However, high-quality trials to verify these findings are warranted.

Automatically steering cardiac catheters in vivo with respiratory motion compensation.

A robotic system for automatically navigating ultrasound (US) imaging catheters can provide real-time intra-cardiac imaging for diagnosis and treatment while reducing the need for clinicians to perform manual catheter steering. Clinical deployment of such a system requires accurate navigation despite the presence of disturbances including cyclical physiological motions (e.g., respiration). In this work, we report results from in vivo trials of automatic target tracking using our system, which is the first to navigate cardiac catheters with respiratory motion compensation. The effects of respiratory disturbances on the US catheter are modeled and then applied to four-degree-of-freedom steering kinematics with predictive filtering. This enables the system to accurately steer the US catheter and aim the US imager at a target despite respiratory motion disturbance. In vivo animal respiratory motion compensation results demonstrate automatic US catheter steering to image a target ablation catheter with 1.05 mm and 1.33° mean absolute error. Robotic US catheter steering with motion compensation can improve cardiac catheterization techniques while reducing clinician effort and X-ray exposure.

Lightweight Highly Tunable Jamming-Based Composites.

Tunable-impedance mechanisms can improve the adaptivity, robustness, and efficiency of a vast array of engineering systems and soft robots. In this study, we introduce a tunable-stiffness mechanism called a "sandwich jamming structure," which fuses the exceptional stiffness range of state-of-the-art laminar jamming structures (also known as layer jamming structures) with the high stiffness-to-mass ratios of classical sandwich composites. We experimentally develop sandwich jamming structures with performance-to-mass ratios that are far greater than laminar jamming structures (e.g., a 550-fold increase in stiffness-to-mass ratio), while simultaneously achieving tunable behavior that standard sandwich composites inherently cannot achieve (e.g., a rapid and reversible 1800-fold increase in stiffness). Through theoretical and computational models, we then show that these ratios can be augmented by several orders of magnitude further, and we provide an optimization routine that allows designers to build the best possible sandwich jamming structures given arbitrary mass, volume, and material constraints. Finally, we demonstrate the utility of sandwich jamming structures by integrating them into a wearable soft robot (i.e., a tunable-stiffness wrist orthosis) that has negligible impact on the user in the off state, but can reduce muscle activation by an average of 41% in the on state. Through these theoretical and experimental investigations, we show that sandwich jamming structures are a lightweight highly tunable mechanism that can markedly extend the performance limits of existing structures and devices.

Male circumcision and prostate cancer: A geographical analysis, meta-analysis, and cost analysis.

INTRODUCTION: Attempts to find an association between male circumcision and prostate cancer risk have produced inconsistent results. METHODS: Age-standardized prostate cancer incidence, life-expectancy, geographical region, and circumcision prevalence from 188 countries were compared using linear regression analysis. Following a systematic literature review, a meta-analysis was performed on studies meeting inclusion criteria with evaluations of between-study heterogeneity and publication bias. A cost analysis (discounted at 3% and 5% per annum) was performed using the meta-analysis's summary effect and upper confidence interval. RESULTS: Univariate analysis revealed a trend for a positive association between country-level age-standardized prostate cancer incidence (per 100 000 person-years) and circumcision prevalence (ß=0.0887; 95% confidence interval [CI)]-0.0560, +0.233), while multivariate analysis found a significant positive association (ß=0.215; 95% CI 0.114, 0.316). Twelve studies were included in meta-analysis. The random-effects summary odds ratio of the risk of being genitally intact was 1.10 (95% CI 0.96, 1.26, between-study heterogeneity χ2 15=27.43; p=0.03; I2=82.8%). There was no evidence of publication bias. Cost analysis found infant circumcision was prohibitively costly, returning only between 1.6¢ and 13.8¢ for each dollar expended. CONCLUSIONS: Circumcision may be a positive risk factor on geographical analysis, but not in case-case-controlled studies. Circumcision is not economically feasible for preventing prostate cancer.

Ultrasound Imaging Characterization of Soft Tissue Dynamics of the Seated Human Body.

To characterize the dynamics of internal soft organs and external anatomical structures, this paper presents a system that combines medical ultrasound imaging with an optical tracker and a vertical exciter that imparts whole-body vibrations on seated subjects. The spatial and temporal accuracy of the system was validated using a phantom with calibrated internal structures, resulting in 0.224 mm maximum root-mean-square (r.m.s.) position error and 13 ms maximum synchronization error between sensors. In addition to the dynamics of the head and sternum, stomach dynamics were characterized by extracting the centroid of the stomach from the ultrasound images. The system was used to characterize the subject-specific body dynamics as well as the intrasubject variabilities caused by excitation pattern (frequency up-sweep, down-sweep, and white noise, 1-10 Hz), excitation amplitude (1 and 2 m/s2 r.m.s.), seat compliance (rigid and soft), and stomach filling (empty and 500 mL water). Human subjects experiments (n = 3) yielded preliminary results for the frequency response of the head, sternum, and stomach. The method presented here provides the first detailed in vivo characterization of internal and external human body dynamics. Tissue dynamics characterized by the system can inform design of vehicle structures and adaptive control of seat and suspension systems, as well as validate finite element models for predicting passenger comfort in the early stages of vehicle design.