Low Disturbance Research Articles

Integrating UAV LiDAR and multispectral data to assess forest status and map disturbance severity in a West African forest patch

Unmanned aerial vehicle (UAV) technologies have emerged as promising tools to improve forest ecosystem assessments. These technologies offer high-resolution data that can significantly enhance evaluations of forest structure, condition, and disturbance severity. UAV sensors such as LiDAR and multispectral provide complementary information about forest attributes, capturing structural and spectral details, yet their integration for comprehensive forest assessment remains understudied. In this paper, we explored the potential of combining UAV LiDAR and multispectral data to assess the disturbance severity of a West African forest patch (Benin). We developed an integrated disturbance index (IDI) that fuses structural properties from LiDAR data and spectral characteristics from multispectral vegetation indices through principal component analysis (PCA). This allowed us to delineate low (> 0.65), medium (0.35–0.65), and high (< 0.35) forest disturbance levels. We applied the IDI to the 560-ha Ewe-Adakplame relict forest in Benin, West Africa, and achieved 95 % overall accuracy in disturbance detection, outperforming both LiDAR-only (80 %) and multispectral-only (75 %) approaches. The IDI revealed that 23 % of the forest area has experienced low disturbance, while 28 % and 49 % face medium and high disturbance levels, respectively. These findings highlight that more than three-quarters of this relict forest is under considerable stress, underscoring the urgent need for tailored conservation strategies to strengthen forest resilience. This method's ability to differentiate disturbance levels can inform resource allocation, prioritize conservation efforts, and guide the development of site-specific management plans. The integration of UAV LiDAR and multispectral data demonstrated here has potential for application across diverse tropical forest patches, providing an effective means to monitor forest health, assess disturbance severity, and support data-driven decision-making in forest conservation and sustainable management.

Roles of Social Support and Strain in Predicting Older Adults’ Sleep Disturbances

Sleep disturbances impact the well-being of older adults, but there has been limited research on their longitudinal patterns and how they are affected by the quality of social relationships. This study explored longitudinal sleep disturbance patterns and examined the influence of social support and social strain on sleep disturbances in older adults using data from the Health and Retirement Study (HRS) spanning from 2010 to 2018. Group-based trajectory modeling identified distinct trajectory groups. Multinomial logistic regression and a fixed effects model investigated the relationship between sleep disturbances, social support, social strain, and sociodemographic factors. Three sleep disturbance trajectories were identified: high sleep disturbances, moderate sleep disturbances, and low sleep disturbances. Multinomial logistic regression showed that higher social support decreased the likelihood of classification in the high and moderate sleep disturbance groups. Conversely, higher social strain scores increased the likelihood of belonging to the high and moderate sleep disturbance groups. The fixed effects model confirmed the role of social support in predicting sleep disturbances over time, but social strain was not a significant predictor. These findings suggest the need for tailored interventions addressing social support to reduce sleep disturbances in this population.

Using open-path dual-comb spectroscopy to monitor methane emissions from simulated grazing cattle

Abstract. Accurate whole-farm or herd-level measurements of livestock methane emissions are necessary for anthropogenic greenhouse gas inventories and to evaluate mitigation strategies. A controlled methane (CH4) release experiment was performed to determine if dual-comb spectroscopy (DCS) can detect CH4 concentration enhancements produced by a typical herd of beef cattle in an extensive grazing system. Open-path DCS was used to measure downwind and upwind CH4 concentrations from 10 point sources of methane simulating cattle emissions. The CH4 mole fractions and wind velocity data were used to calculate CH4 flux using an inverse dispersion model, and the simulated fluxes were then compared to the actual CH4 release rate. For a source located 60 m from the downwind path, the DCS system detected 10 nmol mol−1 CH4 horizontal concentration gradient above the atmospheric background concentration with a precision of 6 nmol mol−1 in 15 min interval. A CH4 release of 3970 g d−1 was performed, resulting in an average concentration enhancement of 24 nmol mol−1 of CH4. The calculated CH4 flux was 4002 g d−1, showing good agreement with the actual CH4 release rate. Periodically altering the downwind path, which may be needed to track moving cattle, did not adversely affect the ability of the instruments to determine the CH4 flux. These results give us confidence that CH4 flux can be determined by grazing cattle with low disturbance and direct field-scale measurements.

CFD-DEM simulation and experimental investigations on continuous hydraulic sampling of deep-sea polymetallic nodules

The physical sampling to grasp the distribution of deep-sea polymetallic nodules is essential for efficient mining. A hydraulic sampling scheme is proposed that balances low environmental disturbance, high sampling precision, broad coverage, and statistical data viability to address the limitations of existing methods. This paper utilizes a coupled approach of Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) to explore innovative solutions for precise and continuous hydraulic sampling of deep-sea polymetallic nodules. Focusing on the optimization of the double-row nozzle sampling mechanism design, simulations are conducted to analyze the dynamic characteristics of solid-liquid two-phase flow during the hydraulic sampling process under various nozzle configurations and operational water pressures of the pump. Laboratory experiments with the hydraulic sampling mechanism validate the accuracy of the simulation and the effectiveness of the optimization suggestions. The configuration is finalized with a front nozzle diameter of 10 × φ9 mm, a rear nozzle diameter of 10 × φ7 mm, and an initial working water pressure for the pump of 80 kPa. Subsequently, integrated driving-sampling experiments are conducted using a self-propelled tracked vehicle, validating the feasibility of the proposed configuration.

Bibliometric Trends and Insights into the Potential of Maize (Zea mays) under the Framework of Conservation Agriculture

In spite of the detrimental effects of climate change and decreasing resource efficiency, maize farming is essential to the world’s food and nutritional security. With regard to sustainable maize farming in this environment, conservation agriculture (CA) offers a framework that holds promise in terms of low soil disturbance, perennial soil cover, and sustainable crop rotation. In order to acquire more profound information on the research advancements and publication patterns related to maize under CA scenarios, a bibliometric analysis was conducted. This involved utilizing René Descartes’s Discourse Framework to extract and screen 2587 documents spanning the years 2001 to 2023 from the Dimensions.ai database. The mapping showed that different stakeholders were becoming more interested in maize research under various CA pathways, with a greater emphasis on reaching the second sustainable development target, or “zero hunger”. The most influential journals were “Soil and Tillage Research” and “Field Crops Research”, with 131 and 85 papers with 6861 and 6186 citations, respectively. The performance analysis found “Christian L. Thierfelder” and “Mangi Lal Jat” as the eminent researchers in the areas of maize research under CA. Thus, the International Maize and Wheat Improvement Center (CIMMYT) and the Indian Agricultural Research Institute (IARI) were identified as the important institutions in conducting research pertaining to maize under CA systems, while the United States, India, and Mexico emerged as prominent countries with notable collaboration efforts for imparting research under the given scenarios. Three thematic clusters delineating keywords from three distinct sections—key drivers, objectives, and methodology—were identified through co-word analysis using word clouds, tree maps, and thematic networking of the keywords from the abstract and titles of screened publications. These thematic clusters highlighted the growing emphasis on region-specific studies under CA, particularly in sub-Saharan Africa and the Indo-Gangetic plain, to enhance the resilience of the agri-food system. Therefore, mapping maize’s potentialities within the CA framework has revealed the field’s dynamic nature and offers insightful information to researchers and policymakers that could help them plan future studies and cooperative initiatives aimed at boosting the productivity and sustainability of maize-based systems under the CA framework.

Effects of Climate, Soil, Topography and Disturbance on Liana Prevalence.

Lianas (woody vines and climbing monocots) are increasing in abundance in many tropical forests with uncertain consequences for forest functioning and recovery following disturbances. At a global scale, these increases are likely driven by disturbances and climate change. Yet, our understanding of the environmental variables that drive liana prevalence at regional scales is incomplete and geographically biased towards Latin America. To address this gap, we present a comprehensive study evaluating the combined effects of climate, soil, disturbance and topography on liana prevalence in the Australian Wet Tropics. We established 31 20 × 20 m vegetation plots along an elevation gradient in low disturbance (canopy closure ≥ 75%) and high disturbance (canopy closure ≤ 25%) forest stands. In these plots, all tree and liana (defined as all woody dicot vines and climbing monocots, i.e., rattans) stems ≥ 1 cm DBH were measured and environmental data were collected on climate, soil and topography. Generalised linear models were used with multi-model averaging to quantify the relative effects of the environmental variables on measures of liana prevalence (liana-tree basal area ratio, woody vine basal area and stem density and rattan stem density). Liana prevalence decreased with elevation but increased with disturbance and mean annual precipitation. The increase in the liana-tree ratio with precipitation was more pronounced for highly disturbed sites. Like other tropical regions, disturbance is an important driver of liana prevalence in Australian rainforests and appears to interact with climate to increase liana-tree ratios. The observed increase in liana-tree ratio with precipitation contrasts findings from elsewhere but is confounded by correlated changes in elevation and temperature, which highlights the importance of regional studies. Our findings show that forests with high disturbance and climatic conditions favourable to lianas are where lianas most likely to outcompete trees and impede forest recovery.

Self-regulatory and self-efficacy mechanisms of weight loss in women within a community-based behavioral obesity treatment.

Given the traditional methods of treating obesity through education on controlling eating and increasing exercise have largely failed beyond the very short term, a more intensive focus on psychosocial correlates of those weight-loss behaviors has been suggested. Multiple behavioral theories incorporate self-regulation, self-efficacy, and mood; however, their interrelations and effects over both the short and long term within cognitive-behavioral obesity treatments remain unclear. Within a novel community-based program with women with obesity who had either low (n = 29) or high (n = 71) mood disturbance scores, there were significant improvements in exercise- and eating-related self-regulation and eating-related self-efficacy-primary targets of that intervention-with no significant difference in those changes by mood disturbance grouping. Changes in the summed exercise- and eating-related self-regulation scores significantly mediated relationships between changes in eating-related self-efficacy and weight (over both 6 and 12months). There were similar results with mediation assessed via the extent exercise-related self-regulation carried over to eating-related self-regulation. In both of those models a reciprocal relationship between self-regulation and self-efficacy changes was indicated. In serial multiple mediation equations, paths of changes in exercise-related self-regulation → eating-related self-regulation → eating-related self-efficacy → weight were significant. However, paths were not significant when change in self-efficacy was entered as the predictor (initial) variable. Findings suggest viability in first focusing on exercise-related self-regulation, then eating-related self-regulation, in the course of increasing self-efficacy and probabilities for inducing enough sustained weight loss to improve obesity-associated health risks. Benefits of field-based research findings generalizing to weight-management applications were suggested.

Visual, Refractive, Functional, and Patient Satisfaction Outcomes After Implantation of a New Trifocal Diffractive Intraocular Lens.

To describe the visual, refractive, functional, and patient satisfaction outcomes of the Clareon® PanOptix® trifocal intraocular lens (IOL). This was a prospective longitudinal descriptive study. Patients who underwent cataract surgery with implantation of Clareon® PanOptix® (Alcon Laboratories, Inc.) were included. Monocular refractive outcomes and visual acuity at distance, intermediate, and near were evaluated 1- and 6-months post-op. Binocular contrast sensitivity (M&S® Technologies), binocular defocus curve, and patient satisfaction with the IOL Satisfaction (IOLSAT) and Questionnaire for Visual Disturbance (QUVID) questionaries were assessed at 6-month post-op. Seventy-six Clareon® PanOptix® were implanted bilaterally in 38 patients. The mean age of the patients was 67.63±5.18 years. At 1-month post-op, the monocular Corrected Distance Visual Acuity (CDVA), CIVA and CNVA were 0.00±0.09, 0.02±0.17, and 0.12±0.12 LogMAR, respectively, and CDVA and CNVA were stable at 6-month post-op (p>0.05). No statistical differences were found in post-op spherical equivalent at 1 and 6 months (-0.08±0.27 D and -0.05±0.24 D; p=0.351). A 100% of eyes were within ±0.5 D at 1 month and 6-month post-op. Binocular defocus curve shows three peaks of maximum visual acuity (VA) at 0D (-0.04±0.08 LogMAR), at -1.50D, and -2.50 D (0.01±0.10 LogMAR and 0.03±0.07 LogMAR, respectively). Contrast sensitivity decreased at high spatial frequencies. In patient satisfaction, IOLSAT questionary reveals 78.94% patients "Never" or "Rarely" Needing Glasses and according QUVID questionnaire, 100% of patients report no hazy vision. The PanOptix® IOL platform with the new material Clareon® provides good visual outcomes for distance, intermediate, and near vision, with adequate contrast sensitivity and low visual disturbances.

Turbulent flow field in maglev centrifugal blood pumps of CH-VAD and HeartMate III: secondary flow and its effects on pump performance.

Secondary flow path is one of the crucial aspects during the design of centrifugal blood pumps. Small clearance size increases stress level and blood damage, while large clearance size can improve blood washout and reduce stress level. Nonetheless, large clearance also leads to strong secondary flows, causing further blood damage. Maglev blood pumps rely on magnetic force to achieve rotor suspension and allow more design freedom of clearance size. This study aims to characterize turbulent flow field and secondary flow as well as its effects on the primary flow and pump performance, in two representative commercial maglev blood pumps of CH-VAD and HeartMate III, which feature distinct designs of secondary flow path. The narrow and long secondary flow path of CH-VAD resulted in low secondary flow rates and low disturbance to the primary flow. The flow loss and blood damage potential of the CH-VAD mainly occurred at the secondary flow path, as well as the blade clearances. By contrast, the wide clearances in HeartMate III induced significant disturbance to the primary flow, resulting in large incidence angle, strong secondary flows and high flow loss. At higher flow rates, the incidence angle was even larger, causing larger separation, leading to a significant decrease of efficiency and steeper performance curve compared with CH-VAD. This study shows that maglev bearings do not guarantee good blood compatibility, and more attention should be paid to the influence of secondary flows on pump performance when designing centrifugal blood pumps.

Risk for low energy availability, disordered eating and sleep disturbance among female football players.

Low energy availability (LEA) and mental health issues are prevalent among female athletes and can have adverse effects on health and sports performance. This study aimed to assess energy availability and, mental health status (depression, anxiety, sleep deprivation, drug misuse, alcohol misuse, and disordered eating) among female football players. Despite the availability of validated tools for the triads and REDs, few studies have focused on the prevalence of LEA and mental health in female football players. Furthermore, limited information is available on LEA and its consequences in India. Professional female football players (n=25) aged 19-30 years were recruited using incidental sampling. LEA was estimated based on energy availability [energy intake - activity energy expenditure] and LEA female questionnaire (LEAF-Q). Sports mental health assessment tool-1 (SMHAT-1) was used to assess the mental health status. Descriptive statistics and chi square test were used to test the hypotheses. According to the factorial method and LEAF-Q, 24% and 12% of players had LEA, respectively. LEA symptoms, such as decreased gastrointestinal and menstrual function, were observed in 16% of participants, while 8% had a history of injury. 44% of the participants exhibited poor mental health. Sleep disturbance (12%) and disordered eating (44%), were among the most common mental health issues. No significant difference was found between LEA, disordered eating, and sleep disturbance. Female football players were more likely to develop LEA and mental health disorders, such as disordered eating and sleep disturbance. LEA was not linked with disordered eating or sleep disturbance. Early detection of LEA and effective intervention enhances the health and performance of female football players.

Fractal fracture characteristics and acoustic emission analysis of soft rock‐coal combinations under low‐frequency disturbance

AbstractTo explore the fracture mode and failure characteristics of soft rock‐coal combinations under different disturbance amplitudes, this paper conducted dynamic uniaxial compression tests under different disturbance amplitudes. The results indicate that low‐frequency disturbances can weaken the load‐bearing capacity of the specimen. The failure modes of specimens vary under different disturbance amplitudes, and low amplitude disturbances are not sufficient to cause overall cracking and failure of the specimens. In addition, as the disturbance amplitude increases, the fractal dimension of the composite after fracture shows a fluctuating trend, reaching its maximum value at 3 MPa and its minimum value at 4 MPa, with an overall range of 1–3. Finally, the absolute energy and waveform characteristics of acoustic emission can display the fracture damage of the specimen during the disturbance process. This study provides a theoretical basis for understanding and preventing coal rock dynamic disasters.

Numerical Study of Low Engine Order Excitations due to Manufacturing Variability Part 1: Characterization of the Geometric Scatter and its Effect on Forced Response

Abstract The geometric scatter in the surfaces of blades and vanes due to manufacturing variability has an impact on the dynamics but also on the aerodynamics. The loss of the spatial periodicity of the flow due to the geometric variations generates an aerodynamic forcing with a wave number different from the airfoil count on the adjacent rows. In this paper, deviations from the nominal geometry are obtained from a set of scanned parts. The average manufactured geometry is computed through the point-by-point deviations between the scanned parts and the nominal geometry. Then, Principal Component Analysis is applied to the deviations from the average geometry to find a way to describe them in a simple manner. The cold geometries are reconstructed using the mean geometry and the PCA geometric modes; afterwards, a cold-to-hot process is applied to obtain the hot geometry, and finally the resulting aerodynamics are obtained using an in-house CFD solver. The described method is applied to a representative row constituted by packets of vanes. Firstly, the average packet geometry is used to analyze the aerodynamic forcing associated to the geometric variation of the airfoils inside the vane packet. After that, a conceptual study is carried out under some simplified assumptions in order to relate the geometric variability to random low engine order disturbances, using the geometric modes obtained from the PCA analysis. In both cases, the induced vibrations on the adjacent rotor row are comparable to the excitation due to the nominal blade-passing.

Recent results and outstanding questions on the response of the electrodynamics of the low latitude ionosphere to solar wind and magnetospheric disturbances

Storm-time ionospheric electrodynamics effects have been the subject of extensive studies. The solar wind/magnetosphere/ionosphere and thermosphere disturbance wind dynamos have long been identified as the main drivers of low latitude storm-time electrodynamics. Extensive detailed studies showed that climatology of low latitude disturbance electric fields and currents is in good agreement with results from global theoretical and numerical models. Over the last decade, however, numerous studies have highlighted that the response of low latitude electrodynamics to enhanced geomagnetic activity is significantly more complex than previously considered. It is now clear that the electrodynamic disturbance processes are affected by a larger number of solar wind and magnetospheric parameters and that they also have more significant spatial dependence. This is especially pronounced during and after large geomagnetic storms when multiple simultaneous disturbance processes are also active. In this work, we briefly review the main past experimental and modeling studies of low latitude disturbance electric fields, highlight new results, discuss outstanding questions, and present suggestions for future studies.

Fertility and tillage intensity affect weed community diversity and functional structure in long-term organic systems.

Knowledge of how agricultural management interacts with weed seed banks and emergent weed communities is crucial for proactive weed management. Though studies have detailed how differences in disturbance and nutrient applications between organic and conventional herbicide-based systems affect weed communities, few have focused on these same factors in contrasting organic systems. This study assessed the seed banks and emergent weed communities from the most recent crop rotation cycle (2017-2022) of a long-term experiment, which compared four organic grain and forage cropping systems differing in nutrient inputs and soil disturbance. The high fertility (HF) system received high-rate nutrient applications, low fertility (LF) received low-rate applications, enhanced weed management (EWM) focused on weed control through frequent soil disturbance, and reduced tillage (RT) prioritized soil health with less intense or frequent soil disturbance. Soil samples for greenhouse germination assays were collected at the beginning (2017) and end (2022) of the rotation to explore how these four systems influenced seed bank dynamics over time. Weed community biomass was also sampled in each crop during this time. Treatment effects on weed abundance, taxonomic diversity, and community-weighted means and functional dispersion of weed traits were analyzed with generalized mixed-effect models. The RT system had the highest weed seed bank taxonomic diversity, and EWM had the lowest. RT and LF had higher functional dispersion of traits than HF in the seed bank. Weed seed bank communities in HF and RT were characterized by short, small-seeded, and early germinating weed species. However, seed banks were also labile: Differences between systems in seed density and all other mean trait values were dependent on the crop, which preceded seed bank sampling. Likewise, differences among emergent weed communities in the four systems depended on an interaction between crop species and their planting year. Results suggest that resource availability and intensity of disturbance act as weed community assembly filters in organic cropping systems. Organic growers seeking to design systems that balance weed management and production goals can use relatively low soil disturbance and nutrient application to increase weed community taxonomic or functional diversity without necessarily increasing weed biomass or seed bank density.

Elevation and Human Disturbance Interactively Influence the Patterns of Insect Diversity on the Southeastern Periphery of the Tibetan Plateau.

The maintenance of biodiversity and ecological balance heavily relies on the diversity of insects. In order to investigate the impacts of elevation and human disturbance, as well as their interactions on insect diversity, we conducted an intensive survey of insects in the Hengduan Mountain Range, which is situated on the southeastern periphery of the Tibetan Plateau in China. A total of 50 line transects were established in this study to investigate the impact of elevation and human disturbance on insect diversity and distribution patterns. Designed insect surveys were conducted at various elevations and levels of human disturbance, and statistical methods such as generalized linear modeling and redundancy analysis were employed for data analysis. The results of this study indicated a negative correlation between insect diversity and elevation. Additionally, moderate disturbance was found to have a positive impact on insect diversity to some extent. The explanatory power of the model for the distribution of insect diversity could be improved if elevation and human disturbance were included as an interaction effect into the model, and there were differences in the effects of human disturbances on insect diversity at different elevation levels. The highest insect diversity was observed under low disturbance conditions below elevation of ~2200 m, whereas above this threshold, insect diversity was the highest under moderate disturbance compared to low disturbance. The response of different insect taxa to the interactions of elevation and human disturbance varied. The findings imply that when formulating strategies for managing insect diversity, it is crucial to thoroughly consider the interaction of environmental factors and disturbance response of individual insect taxa.

Phyto-sociological changes in the Goima Forest, Gujarat due to human disturbances and their implications for conservation

Aim: The study aimed to understand the phytosociological changes by the impact of forest fringe human disturbance on the Goima forest of Valsad district in Gujarat. Methodology: The study area was classified into different tree canopy density and disturbance classes, and ecological indices were calculated for each class following the quadrate survey method. Results: A total of 772 individual plants of 141 species from 53 families were recorded during quadrate sampling, with variations in aspects being especially important predictors of biotic diversity. The study found that the maximum taxa of trees (30), herbs (24), and grasses (7) were reported in the high-disturbance class, while for shrubs (16) and climbers (10), it was in the middle-disturbance class. Dominance (D)was higher in the moderately dense forest as well as in the moderate disturbance class for trees (0.11, 0.13), shrubs (0.24, 0.21), herbs (0.13, 0.12), but for climbers, D was higher in dense forest (0.40) and in moderate disturbance class (0.22), and for grasses, it was higher in the moderately dense forest (0.69) and less disturbed class (0.58). Shannon's index (H) for trees (2.93), herbs (2.85), and grasses (1.68) was maximum in the higher disturbance class, while for shrubs (2.23) and climbers (2.10), it was highest in the low disturbance class. Interpretation: The study highlights that the phytosociology of the Goima forest changes due to human disturbances. The importance of understanding and conserving biodiversity in the Goima forest, especially given its unique flora and its critical role in supporting local communities. The research provides valuable scientific information that can aid in the better management and protection of the forest area. Key words: Canopy class, Goima forest, Human disturbance, Phytodiversity, Species distribution

Fuzzy averaging level control for tight product quality control

AbstractThis work develops a fuzzy averaging level controller (ALC) to mitigate flow variability while avoiding high and low level alarm limit breaches. Comparison with proportional (P) and proportional integral (PI) level controllers and their non‐linear variants demonstrates the fuzzy controller to be highly effective in mitigating flow transients for low and moderate size flow disturbances. The performance is comparable for large disturbances. Application of the developed fuzzy ALC to a ternary benzene‐toluene‐xylene direct split separation scheme as well as the separation section of a conventional cumene process demonstrates significantly superior product quality control due to flow transient variability mitigation. The product quality control variability is reduced by up to 1.5 times. The developed fuzzy ALC is therefore suitable for plant‐wide control applications.

Modeling of a six-degree-of-freedom magnetic levitation platform actuated by noncontact Lorentz forces

In this study, the modeling of a six-degree-of-freedom (DOF) magnetic levitation platform actuated by noncontact Lorentz forces was analyzed. First, an analytic model of the actuator forces was studied, and the magnetic flux density in the working gap of the actuators was established using the Image Method, Ampere molecular hypothesis, and Biot–Savart law. The dynamics model of the floater actuated by the actuators was then built using the Newton–Euler method. Moreover, the double-pendulum chaotic nonlinear system of the hoisted floater was simplified as a single-DOF system, in which the interaction effects between two DOFs were considered. Furthermore, modeling of the platform control system was performed, which included an acceleration measuring unit with six uniaxial accelerometers, a position measuring unit with three two-dimensional PSDs, and a control unit that decouples the six-DOF control. Finally, an experimental setup was built to perform ground tests on the platform. The results verified the platform modeling; translational and rotational positioning accuracies were approximately 5 μm and 40 μrad at the six DOFs, respectively, and the vibrational suppression efficiencies were greater than 90% for low frequency disturbances. Moreover, Kalman estimators and disturbance observers were introduced into the controller to estimate the movement of the floater and observe the direct disturbance. Simulation testing demonstrated a significant improvement in the vibration-suppression performance of the platform.

Inflammatory and Oxidant Responses to Arduous Military Training: Associations with Stress, Sleep, and Performance.

Arduous military training frequently consists of prolonged physical activity, sleep disturbance, and stress that increases musculoskeletal injury risk and performance decrements. Inflammatory and oxidative stress responses have been reported in response to arduous training, but with inconsistencies across markers and with under-representation of women. The purpose of the current report was to measure circulating inflammation and oxidative stress responses to military training and to correlate biomarkers with subjective measures of stress and sleep quality as well as military fitness test performance. Candidates undergoing the 10-week Marine Corps Officer Candidate School (OCS; 101 men; 62 women) were monitored, with demographic and questionnaire data collected, and blood drawn before and after OCS. Blood was analyzed for six markers of inflammation and three markers of oxidative stress. Associations between biomarkers and questionnaire and fitness test performance were tested. All measured inflammatory markers as well as plasma antioxidant capacity were elevated following OCS. The inflammatory increase was higher in women for several markers. Sleep disturbance and stress perception were associated with IL-6, IL-10 and CRP concentrations, suggesting that low sleep disturbance and stress perception were associated with low inflammatory load. Additionally, those with the highest inflammation at each time point performed worse on fitness tests than those with low inflammation. Following arduous military training, the circulating environment in a significant portion of officer candidates resembled chronic low-grade inflammation. This circulating inflammatory environment appeared worse with poor sleep, high stress perception, and poor fitness test performance, with utility observed for CRP, IL-6, and IL-10 as biomarkers of these responses. Since inflammation may contribute to musculoskeletal injury and performance decrements, minimizing chronic inflammation during military training should be explored.

The mechanism of low strain rate and moderate principal stress effects in triaxial prestressed marble under lateral impulsive load

Stress waves have a significant impact on the strength and deformation characteristics of deep rock masses at a certain distance from the epicenter or explosion source. In order to study the dynamic responses of deep-buried marble under the disturbance condition, the true triaxial compression test (TTC), the true triaxial disturbed compression test with lateral impulsive load (TTDC) and the synchronous acoustic emission monitoring on the marble were respectively conducted to simulate the influencing process of the seismic wave. The test results show that under lateral impulsive load, a ‘short-range plateau’ phenomenon occurs in the stress-strain curves of the marble samples. With the increase of intermediate principal stress σ2, the ‘short-range plateau’ of ε2 and ε3 curves gradually shrinks and even disappears, and the anisotropy of sample deformation becomes more obvious. The σ2 significantly affects the microfracture activity and the evolution of energy inside the samples under the impulsive load in the whole process of true triaxial disturbed compression. The lateral impulsive load weakens the marble strength which shows an obvious low strain-rate disturbance effect. The marble samples under the impulsive load have a high sensitivity to axial load and are liable to form local brittle fracture. This fracture induced by local stress concentration and strain energy release becomes more pronounced when the axial load is further applied to the samples. By contrast, the impulsive load in σ2 direction has a protective effect on limiting the lateral deformation of the samples and improving its axial deformation capacity, which greatly changes the action mechanism of σ2 on the sample lateral deformation. The variation of marble mechanical properties under lateral impulsive load is the result of the interaction between the low strain-rate disturbance and the intermediate principal stress effect.