Mass Parameters Research Articles

Identification of the tip mass parameters in a beam-tip mass system using response surface methodology

Abstract In this study, a response surface based approach is introduced to determine the physical parameters of the tip mass of a beam – tip mass system, such as mass, mass moment of inertia and coordinates of the centre of gravity with respect to the beam end point. To this end, first, a difference function was formulated based on the differences between the peak frequencies and peak amplitudes of the experimental and analytical frequency response functions. Later, observation points were established in the design space using orthogonal arrays, and a response surface was developed using the difference function values at these points. Next, the tip mass parameters were determined by minimizing the response surface with genetic algorithm and particle swarm optimization as well as fmincon, a gradient-based solver of the Matlab program. For comparison purposes, those parameters were obtained by also direct minimization of the difference function with the same algorithms. It was concluded that the tip mass parameters were successfully determined within reasonable error limits by the response surface method with less computational burden. Finally, the effect of design space width on the response surface quality is demonstrated numerically.

Thermodynamics with conformal Killing vector in the charged Vaidya metric

We investigate the charged Vaidya spacetime with conformal symmetry by classifying the horizons and finding its connection to Hawking temperature. We find a conformal Killing vector whose existence requires the mass and electric charge functions to be proportional, as well as linear in time. Solving the Killing equations for the conformally transformed metric from the linear charged Vaidya metric yields the required form of the conformal factor. From the vanishing of the norm of the conformal Killing vector, we find three conformal Killing horizons which, under the transformation, are mapped to the Killing horizons of the associated static spacetime, if the spherical symmetry is maintained. We find that the conformal factor is not uniquely determined, but can take any function of the ratio of the radial coordinate to the dynamical mass. As an example, we illustrate a static spacetime with our choice of the conformal factor and explicitly show that the surface gravity of the conformal Killing horizons, which is conformally invariant, yield the expected Hawking temperature in the static spacetime. This static black hole spacetime contains a cosmological horizon, but it is not asymptotically de Sitter. We also investigate the case when the mass parameter is equal to the constant electric charge. While in this case the standard pair of horizons, the loci of the time component of the metric, degenerate, the conformal Killing horizons do not degenerate. This therefore leads to a non-zero Hawking temperature in the associated static spacetime.

Electron effective mass in GaN revisited: New insights from terahertz and mid-infrared optical Hall effect

Electron effective mass is a fundamental material parameter defining the free charge carrier transport properties, but it is very challenging to be experimentally determined at high temperatures relevant to device operation. In this work, we obtain the electron effective mass parameters in a Si-doped GaN bulk substrate and epitaxial layers from terahertz (THz) and mid-infrared (MIR) optical Hall effect (OHE) measurements in the temperature range of 38–340 K. The OHE data are analyzed using the well-accepted Drude model to account for the free charge carrier contributions. A strong temperature dependence of the electron effective mass parameter in both bulk and epitaxial GaN with values ranging from (0.18 ± 0.02) m0 to (0.34 ± 0.01) m0 at a low temperature (38 K) and room temperature, respectively, is obtained from the THz OHE analysis. The observed effective mass enhancement with temperature is evaluated and discussed in view of conduction band nonparabolicity, polaron effect, strain, and deviations from the classical Drude behavior. On the other hand, the electron effective mass parameter determined by MIR OHE is found to be temperature independent with a value of (0.200 ± 0.002) m0. A possible explanation for the different findings from THz OHE and MIR OHE is proposed.

Kinematics analysis on accelerated motion using tracker video analysis for educational purposes

This study aims to determine the effectiveness of video analysis tracker-based practicum on the material of the motion of objects on an inclined plane and the motion of objects in free fall. The use of video tracker analysis-based practicum is useful for determining some kinematics parameters of objects that cannot only be calculated by traditional practicum methods. By using the video tracker analysis method, all object kinematics parameters can be found directly in visual form. The results show that (1) There is no relationship between mass and kinematics parameters. (2) There is an influence due to air friction on the acceleration value of the object. (3) The suitability of the concept with the tracker application produced with the error value in the experiment of object motion on an inclined plane () (4) The suitability of the concept with the tracker application produced with the error value in the experiment of object motion in free fall () (5) The graphical representation of the tracker is in accordance with the theory studied. This research implies that the existence of learning using practicum, especially practicum-based video tracker analysis can improve understanding and process skills in understanding science concepts. This research is written so that the programme can be further applied to science education.

The relationship between muscle quality index and physical function in older adults

BACKGROUND: The muscle quality index (MQI) has been proposed as a diagnostic tool to detect individuals at risk of limited physical function. OBJECTIVE: Our goal was to examine the relationship of the MQI with physical function and compare its predictive ability with other muscle parameters of strength and mass in an older population. METHODS: Sixty-eight healthy older adults (34 male, 34 female) aged between 69 and 89 years were tested for body composition, MQI, maximum isokinetic concentric KES and physical function including sit-to-stand (STS) time, normal and maximum walking speed (WS), Timed Up and Go (TUG) and static balance. Pearson’s correlation was applied to examine the relationship between muscle parameters. Linear regression analysis including age and sex as additional covariates was performed to assess their predictive ability for physical functions. RESULTS: MQI correlated significantly with relative KES (r= 0.611, p< 0.001), total KES (r= 0.829, p< 0.001) and leg lean tissue mass (r= 0.690, p< 0.001). The MQI was not a significant predictor for any physical function (p> 0.05). STS time was a significant predictor for normal WS and TUG time (p< 0.001). Relative KES was a significant predictor for all physical functions except static balance (p< 0.001). No muscle parameter and only age was a significant predictor for static balance. Models explained 20.4%–57.3% of variances of dependent variables. CONCLUSIONS: The MQI is a useful tool to assess leg lean tissue mass and strength of the knee extensor muscles and outperforms STS time. However, STS time and relative KES are more closely related to physical function than the MQI.

P842 Assessment of body composition parameters in patients with inflammatory bowel disease treated with biological therapy

Abstract Background There is growing evidence of the role of biological therapy (BT) in improving body composition parameters (BCP) in inflammatory bowel disease (IBD) patients. Since myopenia and high adiposity affect prognosis and could lead to treatment failure, there is the need for expanding the assessment of BCP in clinical practice beyond traditional measures like body mass index (BMI). Methods A cross-sectional study included 151 IBD patients treated with BT (80 males, 83 Crohn`s disease, 68 ulcerative colitis, mean age 37). Bioelectrical Impedance Analysis (InBody170) was done to estimate: body weight, BMI, skeletal muscle mass (SMM), body fat mass (BFM), percent body fat (PBF), fat free mass (FFM). Dividing SMM, FFM and BFM by height squared, we calculated the skeletal muscle mass index (SMI), fat-free mass index (FFMI) and fat mass index (FMI). Results In relation to BMI, 84 (55.6%) patients had healthy weight, 41 (27.2%) were overweight, 13 (8.6%) were obese and 13 (8.6%) were classified as underweight. Clinical remission was present in 139 (92.6%) patients. The average values of the measured BCP are as follows: body weight 71.7kg (41.4-123.7); body height 174.6±10.9cm; BMI 23.7kg/m2 (15.1-36.9); PBF 24.6% (5-48); SMI 9.7kg/m2 (6.3-13.5); FFMI 17.5kg/m2 (12.0-23.5); FMI 5.7kg/m2 (1.0-17.3). Muscle mass parameters were significantly higher in the group of patients treated with BT longer than 3 months (SMI p=0.01, FFMI p=0.02), while in the group of patients treated longer than 1 year we observed, apart from muscle mass parameters, a significant increase in adiposity parameters (FMI p=0.02, PBF p=0.06). [WU1] Patients who previously had the need for change of BT type had significantly higher values of FMI (p=0.04). Patients with extraintestinal manifestations (EIMs), compared to the group without EIMs, had statistically significantly lower values of body weight (p=0.02), SMI (p=0.01), and FFMI (p= 0.01). There was no statistically significant difference in BCP by IBD subtype, presence of clinical remission, BT type and protocol, previous operations, corticosteroids, mesalazines and azathioprine use. Conclusion The duration of treatment with BT can significantly affect muscle mass and adiposity parameters, leading to improved muscle mass parameters after 3 months of therapy, while an increase in adiposity markers is observed after 12 months of BT. Our findings suggest a potential association between EIMs and muscle mass alterations, as well as a relationship between the need for a change in BT type and higher adiposity parameters.

Gravitational Waves from Nnaturalness

We study the prospects for probing the Nnaturalness solution to the electroweak hierarchy problem with future gravitational wave observatories. Nnaturalness, in its simplest incarnation, predicts N copies of the Standard Model with varying Higgs mass parameters. We show that in certain parameter regions the scalar reheaton transfers a substantial energy density to the sector with the smallest positive Higgs squared mass while remaining consistent with bounds on additional effective relativistic species. In this sector, all six quarks are much lighter than the corresponding QCD confinement scale, allowing for the possibility of a first-order chiral symmetry-breaking phase transition and an associated stochastic gravitational wave signal. We consider several scenarios characterizing the strongly-coupled phase transition dynamics and estimate the gravitational wave spectrum for each. Pulsar timing arrays (SKA), spaced-based interferometers (BBO, Ultimate-DECIGO, μAres, asteroid ranging), and astrometric measurements (THEIA) all have the potential to explore new regions of Nnaturalness parameter space, complementing probes from next generation cosmic microwave background radiation experiments.

Analysis of albedo and disc effects in the generalized restricted four-body problem

This manuscript explores the Generalized Restricted Four-Body Problem within the context of radiation pressure, the albedo effect, oblateness, and a disc-like structure that orbits around the primary bodies. We have considered that one of the primaries is a bigger primary, and the rest of the two smaller primaries are of equal masses, in which one of the smaller primaries is considered as a black body. Moreover, the perturbing forces by the effect of radiation pressure and oblateness are considered in the bigger primary. The effect of albedo and oblateness due to the second smaller primary is also taken into count. This study yields nine equilibrium points corresponding to various parameter values, including three collinear and six non-collinear equilibria. We conduct an analysis of the equilibrium points, their linear stability, and the motion around them. In the context of the considered parameter set, certain collinear equilibrium points exhibit stability, while others are unstable. Additionally, most of the non-collinear equilibrium points display linear stability. We also investigate variations in Jacobi’s constant and the positions of existing equilibrium points caused by the albedo and disc effects. It is found that the value of Jacobi constant CLj decreases with an increase in the mass parameter μ at the collinear points, which results in an expansion in the prohibited region. The inhibited zone of motion of the infinitesimal body is shown for different sets of parameters.

Quantitative estimation method for the excavation-induced weakening effect of rock mass parameters in deep tunnels

The excavation-induced weakening effect of rock mass parameters is detrimental to the stability of deep tunnels. This study presents a quantification method for the weakening effect of rock mass parameters. In this method, the weakening factor is introduced as a quantitative index of the weakening effect of rock mass parameters, which can be calculated by the acoustic P-wave velocity measured in the surrounding rock and the Hoek–Brown criterion. Taking three deep tunnels as examples, the weakening law of rock mass parameters is investigated. The results indicate that the weakening effect is most severe near the excavation outline and gradually decays with increasing distance. Significant differences in the weakening effect can be observed at different parts of the tunnel cross-section and under different excavation methods. The weakening effect can be further exacerbated by multiple excavation disturbances. Among the strength parameters of rock masses, the weakening effect of uniaxial compressive strength is the most obvious, followed by uniaxial tensile strength, cohesive strength, and equivalent internal friction angle. The FLAC3D software is utilized to reproduce different weakening effects and analyze the energy distribution around tunnels. It is found that as the weakening effect intensifies, the accumulated elastic strain energy within the surrounding rocks gradually diminishes, and the peak elastic strain energy is at the junction of damaged and undamaged rock masses.

Adaptive trajectory tracking control for VTOL UAVs with unknown time‐varying mass using an extended I&I estimator

SummaryThis article presents an adaptive control scheme for vertical takeoff and landing unmanned aerial vehicles subject to time‐varying mass based on the immersion and invariance scheme in an extended form. For the varying mass parameter in the position control, a generalized I&I adaptive law is proposed with higher dimension to estimate the mass and its derivatives. The stability of the resulting estimation error manifold, which is in a cascade form, is guaranteed by introducing smooth saturation functions in the position control law. The attitude control is designed by employing a smooth function with positive integrable time‐varying function to compensate unknown time‐varying moment of inertia to achieve asymptotic attitude tracking. Simulation and experimental results verify the effectiveness of the proposed method under different cases, and the robustness to time‐varying parameter is assured.

The distribution of stellar orbits in eagle galaxies – the effect of mergers, gas accretion, and secular evolution

ABSTRACT The merger history of a galaxy is thought to be one of the major factors determining its internal dynamics, with galaxies having undergone different types or mergers (e.g. dry, minor, or major mergers) predicted to show different dynamical properties. We study the instantaneous orbital distribution of galaxies in the eagle simulation, colouring the orbits of the stellar particles by their stellar age, in order to understand whether stars form in particular orbits (e.g. in a thin or thick disc). We first show that eagle reproduces well the observed stellar mass fractions in different stellar orbital families as a function of stellar mass and spin parameter at z = 0. We find that the youngest stars reside in a thin disc component that can extend to the very inner regions of galaxies, and that older stars have warmer orbits, with the oldest ones showing orbits consistent with both hot and counter-rotating classifications, which is consistent with the trend found in the Milky Way and other disc galaxies. We also show that counter-rotating orbits trace galaxy mergers – in particular dry mergers, and that in the absence of mergers, counter-rotating orbits can also be born from highly misaligned gas accretion that leads to star formation.

Optimization design of load-sharing and light weight of the twin rotors concentric face gear power-split transmission system based on gear tooth matching condition

To improve the dynamic load-sharing performance and achieve lightweight, the twin rotors concentric face gear power-split transmission system (TRFGPSTS) was optimized. The gear tooth matching conditions of the system based on the design characteristics of power flow closed-loop and virtual constraint configuration of the system are established, and the basic parameters of each gear meet the requirements of the system load-sharing layout and synchronous meshing of each branch movement are calculated. Based on the lumped mass parameter method, combined with the calculation results of gear tooth matching, the 45-DOF bending torsional coupling dynamic model of the system was established considering time-varying meshing stiffness, support stiffness, manufacturing and installation errors, and other factors, and the influence of each factor on the dynamic load-sharing performance of the system was analyzed. Combined with the influence law of various factors, a multi-objective dynamic load-sharing optimization design model was established with the best dynamic load-sharing performance and the minimum system quality as the objective function. Through the weighted combination method, the global optimal solution of the system optimization design was determined, and the influence of each parameter on the optimization objective function was analyzed. The correctness of the results was verified by using the genetic algorithm based on Pareto frontier distribution. The results show that the dynamic load-sharing characteristics of the system become worse with the increase of error and torsional stiffness, and are more sensitive to the influence of various error parameters. The optimization process focuses on the geometric parameters such as the Module, the teeth Number, the Pressure angle, and the Tooth width of each gear, which can reflect the degree of influence on the dynamic load-sharing and lightweight of the system. After optimization, the dynamic load sharing coefficient (DLSC) was reduced to 1.017, and the overall geometric volume was reduced to 1.473 × 108 mm3. It provides a theoretical basis for the design and research of a new type of helicopter power transmission system with a compact structure, good maneuverability, and high reliability.

Coupling of high-temperature proton exchange membrane fuel cells with methanol steam reforming: Modeling and simulation for an integrated coupled for power generation system

This study established a zero-dimensional numerical model integrating methanol steam reforming (MSR) and high-temperature proton exchange membrane fuel cells (HT-PEMFC), systematically investigating the effects of parameters such as steam-methanol (S/C) ratio, reformer reaction temperature, methanol catalytic combustion ratio, fuel cell number, and anode stoichiometry on the thermal, mass, electrical, and efficiency performance parameters of the integrated system. The results confirmed that the integrated system can achieve thermal self-sustained operation without the need for additional heat from methanol catalytic combustion. Improved insulation quality enables the attainment of thermal self-sufficiency at lower operating conditions. The molar ratio of CO in the reformate increases with a decrease in the S/C ratio and an increase in the reformer reaction temperature. The system achieves maximum output power and efficiency when S/C equals 1.25 and the reformer temperature is 513 K, with increases of 8.6 % and 37.1 %, respectively. The system efficiency is highly sensitive to the anode stoichiometry of the fuel cell, showing an 11.7 % improvement as the stoichiometry decreases from 2.0 to 1.2. Based on these results, three improvement measures were proposed to enhance the performance of MSR and HT-PEMFC integrated systems: improving system insulation to lower thermal self-sufficiency conditions, optimizing the stoichiometry of the bipolar plates for significant efficiency improvement, and selecting appropriate operating parameters for system components to enhance overall performance. This study quantitatively demonstrates the potential of these measures to improve system performance, providing valuable insights for the design and optimization of integrated systems.

Three-dimensional reconstruction optimization of tunnel face and intelligent extraction of discontinuity orientation based on binocular stereo vision

In the process of grading and dynamically optimizing the design and construction parameters of the surrounding rock mass of a rock tunnel face, efficiently and accurately acquiring the geometrical parameters of the rock discontinuities is an important basic task. To address the problems of time consuming, low accuracy, and high danger associated with traditional methods of obtaining the structural information of rock mass, this paper proposes a method for three-dimensional reconstruction and intelligent information extraction of tunnel face based on binocular stereo vision (BSV). First, the parallel binocular device with a single camera was improved, calibrated using the checkerboard calibration method. By integrating with the semi-global matching algorithm, the BSV based method for the three-dimensional reconstruction of the rock mass of the tunnel face was optimized. Furthermore, based on the results from on-site engineering applications, this study leveraged two parameters, point cloud density and algorithm runtime, to determine the optimal values for the disparity range and window size parameters within the semi-global stereo matching algorithm. This enhancement improved the performance of the 3D reconstruction method based on binocular stereo vision. Finally, efficient and refined intelligent methods for extracting structural parameters of the rock mass were proposed based on k-nearest neighbor search and kernel density estimation. The research results can provide reliable technical support for the intelligent and efficient acquisition of rock mass structural information in rock tunnel engineering faces.

Age- and sex-specific normative values for muscle mass parameters in 18,625 Brazilian adults.

The present study aimed to provide age- and sex-specific normative values for muscle mass parameters in Brazilian adults. Data pertaining to Brazilian adults (18+ years) who attended a nutritional clinical between January 2018 and July 2022 were analyzed. Muscle mass parameters were assessed using a bioimpedance digital scale (InBody 230, GBC BioMed NZ). Assessments were conducted under standard conditions, with participants refraining from physical exercise for 96 h and from eating or drinking (including water) for 8 h before evaluations. A total of 18,625 Brazilian adults were analyzed. Normative values for absolute and relative (height, m2) muscle mass and appendicular muscle mass (ASM) were calculated. In addition, specific age-related changes in muscle mass parameters were observed. In women, muscle mass peaked between the ages of 40-49 before gradually declining at an average rate of 5.7% per decade from the sixth decade of life onwards. ASM reached its peak earlier, during the third decade of life, and started to decline later, from 50 to 59 years. In contrast, absolute and ASM peaked at 40-49 years and declined from the sixth decade of life in men. Both sexes displayed a slightly greater decline in ASM than in muscle mass (13 vs. 12%). The present study provides normative values for absolute and relative muscle mass and ASM in Brazilian adults. Furthermore, important specific age-related changes in muscle mass parameters were observed. These data have public health implications and might serve as a reference tool to guide health professionals.

Electroweak phase transition with radiative symmetry breaking in a type-II seesaw model with an inert doublet

We consider the type-II seesaw model extended with another Higgs doublet, which is odd under the Z2 symmetry. We look for the possibility of triggering the electroweak symmetry breaking via radiative effects. The Higgs mass parameter changes sign from being positive at higher-energy scales to negative at lower-energy scales in the presence of the TeV scalar triplet. The Planck scale perturbativity is demanded and the electroweak phase transition is studied using two-loop β-functions. The maximum allowed values for the interaction quartic coupling of the second doublet field and the triplet field with the Higgs field are λ3=0.15 and λΦ1Δ=0.50, respectively. Considering these EW values, the first-order phase transition, i.e., ϕ+(Tc)/Tc∼0.6 is satisfied only for vanishing doublet and triplet bare mass parameters, mΦ2=0.0 GeV and mΔ=0.0 GeV. The small nonzero induced vacuum expectation value for the scalar triplet also generates the neutrino mass, and the lightest stable neutral particle from the inert doublet satisfies the dark matter constraints for the chosen parameter space. The impact of the thermal corrections on the stability of the electroweak vacuum is also studied, and the current experimental values of the Higgs mass and the top mass lie in the stable region both at the zero temperature and the finite temperature. Published by the American Physical Society 2024

Association of the IL1A and IL6 polymorphisms with posttraining changes in body mass, composition, and biochemical parameters in Caucasian women.

Polymorphisms located in IL1A and IL6 are promising markers of obesity-related traits; however, studies concerning their potential impact on the effectiveness of lifestyle interventions are lacking. Therefore, the aim was to examine the association between the polymorphic sites located in IL1A (rs1800587) and IL6 (rs1800795, rs1800796, and rs1800797) and the body's response to a 12-week training program. We studied the genotype distribution in a group of 168 Caucasian females in whom body mass and composition parameters, the lipid profile, and glucose levels were measured before and after the exercise period. Our results showed that carriers of the IL1A rs1800597 CC genotype exhibited a significant decrease in total body water (TBW) in response to training (p = 0.045). Additionally, carriers of the IL6 rs1800797 GG and GA genotypes demonstrated a posttraining decrease in body mass index (BMI) (p = 0.039). Haplotype analysis revealed that only rare haplotypes, namely, GGA, CGG and CCG (rs1800795, rs1800796, and rs1800797, respectively), were linked to changes in phenotype, yet assessing individual haplotype effects was not possible. Studies of the interactions between these genes showed that carrying the TC-GG genotype (rs1800587-rs1800795 and rs1800587-rs1800796) may be associated with greater posttraining decreases in fat mass percentage (%FM) and fat-free mass (FM). Carriers of the CC-CG genotype (rs1800587-rs1800795) had significantly greater changes in triglycerides (TGL) over the training period. Our study showed that the IL1A and IL6 genotypes, either individually, in haplotype, or in gene-gene combination, may modify training-induced changes in body mass, composition, glucose levels, and the lipid profile in healthy women.

Peciliarities of Hormonal Regulation of Growth Rate and Generative Functions of Fishes under Increased Anthropogenic Influence

The hydrochemical parameters, the production and destruction of organic substances in different areas on the Ros and Protoka rivers were studied. Nearby the Horodyshche vil. (Ros River) and Pishchana vil. (Protoka River), concentration of ammonium nitrogen exceeded control values 2-5 times, nitrites - 1.5-2.5 times, nitrates - almost 3.0-5.8 times (as control the Ros River in the Olexandria dendrological park was used). Water of the considered sections was significantly contaminated by pesticides (chlorpyriphos) from the adjacent territories. Elevated content of nutrients in water conditioned intensive production processes (Pishchana vil.), whereas high chlorpyriphos content (Gorodyshche vil.) along with significant concentration of chlorpyriphos (Gorodyshche vil.) suppressed organic matters' production. The water quality deterioration and presence of the toxic contamination caused decrease of the size-mass parameters of common ruff, river perch and common rudd, mainly owing to decrease of somatotropin content in blood. The gonadosomatic index of perch and rudd females from contaminated water bodies increased, whereas in males it decreased as compared with the control. The relative and absolute fertility of rudd increased along with increase of the contamination degree. The females' fertility growth under the unfavorable conditions was associated with increase of the estradiol content in blood. The perch and rudd males were characterized by decrease of the gonadosomatic index along with decrease of the testosterone content in blood. Decrease of size and mass parameters and increase of the females' fertility is an adaptive response aimed at the population maintaining and higher vitality under toxic environment. These processes are provided by hormonal regulation of metabolic processes.

Biotechnological potential of growth-promoting bacteria in cotton (Gossypium hirsutum L.) crop

Studies involving plant growth-promoting bacteria are attracting increasing attention in the agricultural sector due to their potential to improve growth and production, and to protect plants from biotic and abiotic stresses. The present study aimed to evaluate the effects of three species of plant growth-promoting bacteria (Bacillus subtilis, Priestia megaterium, and Priestia aryabhattai) on the growth and morphological and biochemical aspects of Gossypium hirsutum L. (cotton) seedlings. The experiment was conducted in a greenhouse with four treatments (one control and three inoculations) and five replications per treatment. The seeds were inoculated by immersion in bacterial suspensions (109CFU/mL) and then sown in pots. The plants were monitored for 60 days. During collection, the plants were measured for the fresh mass of roots and shoots, the height of the shoots, stem diameter, and number of leaves. Leaf samples were collected and used for biochemical analyses. The results obtained showed that seeds treated with P. aryabhattaihad significant improvements in the parameters of fresh mass, plant height, stem diameter, and number of leaves, and in the contents of chlorophyll (a, b, and total), nitrogen, and proteins concerning plants in the control treatment. Plants treated with P. megaterium also achieved improvements in fresh mass, stem diameter, nitrogen, and protein contents. These results indicate the potential of these plant growth-promoting bacteria for use in cotton crops and can be employed in the preparation of biostimulants and biofertilizers.

Bioimpedance analysis of body composition and rest energy expenditure in highly trained cross-country skiers

The body composition monitoring using bioimpedance analysis (BIA) is important in assessing the functional state of athletes in sports. Based on changes of body composition, it is possible to optimize the actual dietary intake, as well as successfully organize the training process. The purpose of this research was to conduct a comparative assessment of BIA parameters and rest energy expenditure (REE) in highly trained cross-country skiers and young non-athletes. Material and methods. The members of the national cross-country skiing team from the Komi Republic and Russian Federation (n=30; age - 22.3±2.7 years) were examined. Practically healthy medical students served as a control group for the present study (n=40; age - 20.2±2.4 years). The participants successively passed the following study steps: assessment of the body composition by BIA (ACCUNIQ BC380), REE determination by indirect non-fasting calorimetry and calculation technique. Results. The parameters of total body water, fat-free mass, lean tissue and body cell mass were higher in contrast to the fat mass percentage in the athletes (р<0.001). The calculated REE was lower than measured REE among all the participants. At the same time, the REE calculated by the Ketch-McArdle formula significantly differed between the groups, while no differences were found between the REE calculated by the Harris-Benedict prediction equation. The measured REE were significantly higher by 16% (p<0.001) i n athletes compared to those in the control group. Conclusion. The body composition of athletes was distinguished by a significantly higher amounts of total body water, fat-free mass, skeletal muscle, active cell mass, and lower percentage of fat mass compared to healthy untrained individuals. The results obtained among athletes coincided with the idea that the magnitude of REE is determined by the mass of metabolically active tissues and to a lesser extent depends on the fat mass. BIA results can be used to monitor athletes' body composition during the training process.