Depth jumps

This paper presents the investigation of the dynamic mechanical properties of coal rock under complex stress conditions at depth, based on the improved Separate Hopkinson Pressure Bar Test System. A total of 15 groups of coal samples were used to perform dynamic impact tests under different conditions. The changing rules of dynamic strength, crushing, fractal dimension and damage modes of coal under different stress conditions were analyzed. A total of nine groups of coal samples were selected for numerical simulation using ANSYS/LS-DYNA...

BACKGROUND: An appropriate teaching mode in physical education is crucial for ensuring effective education outcomes. Given the dynamic nature of the COVID-19 pandemic, teaching modes are often adjusted. However, there is a lack of in-depth research on the impact of different teaching modes on the outcomes of physical education. Our study aims to address this gap by conducting a comparative analysis of the teaching effectiveness of three different physical education modes among Chinese college students, with a focus on evaluating their impact on physical fitness...

No studies have reported ground reaction force (GRF) profiles of the repeated depth jump (DJ) protocols commonly used to study exercise-induced muscle damage. Furthermore, while compression garments (CG) may accelerate recovery from exercise-induced muscle damage, any effects on the repeated bout effect are unknown. Therefore, we investigated the GRF profiles of 2 repeated bouts of damage-inducing DJs and the effects of wearing CG for recovery. Nonresistance-trained males randomly received CG (n = 9) or placebo (n = 8) for 72 hours recovery, following 20 × 20 m sprints and 10 × 10 DJs from 0...

Tool wear is one of the main causes of failure during diffraction grating ruling. However, no theoretical model for tool wear analysis has been available to date. A mathematical model is established here to solve for the friction coefficient at the tool contact position for the first time. Based on the ruling principles for diffraction gratings, four parameters comprising the tool cutting edge radius, knife angle, pitch angle, and tool ruling depth, are introduced into the model. The positive pressure and shear stress acting on the tool contact surface element during plastic deformation of the metal film layer are given, and an integral is performed over the area where the tool meets the metal film layer...

As a carcinogenic and highly neurotoxic hazardous gas, benzene vapor is particularly difficult to be distinguished in BTEX (benzene, toluene, ethylbenzene, xylene) atmosphere and be detected in low concentrations due to its chemical inertness. Herein, we develop a depth-related pore structure in Cu-TCPP-Cu to thermodynamically and kinetically enhance the adsorption of benzene vapor and realize the detection of ultralow-temperature benzene gas. We find that the in-plane π electronic nature and proper pore sizes in Cu-TCPP-Cu can selectively induce the adsorption and diffusion of BTEX...

Researchers commonly use the 'free-fall' paradigm to investigate motor control during landing impacts, particularly in drop landings and depth jumps (DJ). While recent studies have focused on the impact of vision on landing motor control, previous research fully removed continuous visual input, limiting ecological validity. The aim of this investigation was to evaluate the effects of stroboscopic vision on depth jump (DJ) motor control. Ground reaction forces (GRF) and lower-extremity surface electromyography (EMG) were collected for 20 young adults (11 male; 9 female) performing six depth jumps (0...

Physical fitness plays a crucial role in determining human health and overall well-being. The objective of the study was to assess the changes in body structure and physical fitness among individuals examined in 2004 and 2022 (persons aged 32-34 and 50-52). The research material consists of data from the Krakow Continuous Study (KCS) of somatic development and physical fitness of people born in 1970 and 1972, conducted in Krakow in the years 1976-2022. In total, in 2004, 103 women and 122 men took part in the study, and in 2022-47 women and 67 men...

BACKGROUND: The use of movement screens as a clinical tool for injury risk assessment requires variables to be extracted across specific phases of interest. While manually selecting task events is the traditional method, automated event detection is an effective technique that maintains consistency across a cohort. This study aimed to examine variations in event identification, comparing manual detection and the application of an automated algorithm, with a specific focus on a drop vertical jump task...

INTRODUCTION: The United States is currently facing an opioid overdose crisis. Research suggests that multiple interventions are needed to reduce overdose deaths including increasing access and retention to medications to treat opioid use disorders (MOUD, i.e., methadone, buprenorphine, and naltrexone) and increasing the distribution and use of naloxone, a medication that can reverse the respiratory depression that occurs during opioid overdoses. However, barriers to MOUD initiation and retention persist and discontinuations of MOUD carry a heightened risk of overdose...

In this work, we have explored Re(I) complexes featuring triphenylpnictogen ( PnPh 3 , Pn = P , As , or Sb )-based coligands and bidentate (neutral or monoanionic) luminophores derived from 1,10-phenantroline ( phen ), as well as from 2-(3-( tert -butyl)-1 H -1,2,4-triazol-5-yl)pyridine ( H(N- t Bu) ). The effect of the increasingly heavy elements on the structural parameters, photoexcited-state properties, and electrochemical behavior as well as the hybridization defects and polarization of the Pn atoms was related to the charges of the main luminophores (i...

OBJECTIVE: The specific objectives of this study were to identify the ethical issues in reporting of health-related events in media and suggest ways to improve it. METHOD: This was a qualitative phenomenological study conducted by APPNA Institute of Public Health, Jinnah Sindh Medical University in collaboration with Institute of Public Health, Khyber Medical University from January to April 2022. A total of 38 focus group discussions and in-depth interviews were conducted either face to face at place of convenience of interviewees or online...

This study investigated PAPE effects of two conditioning activities (CA) and recovery times on the peak jumping power (PP) of elite female volleyball athletes. Players performed CA separately: three sets of three repetitions of back squats with 85% of 1RM (BS) or one set of five depth drops (DD). PP was measured with countermovement (CMJ) and squat jumps (SJ) before (pre-test) and two minutes (post-test 1) and six hours (post-test 2) after each CA. BS significantly reduced PP at post-test 1 (CMJ and SJ: p < 0...

Philipp, NM, Cabarkapa, D, Blackburn, SD, and Fry, AC. Dose-response relationship for external workload and neuromsuclar performance over a female, collegiate, basketball season. J Strength Cond Res XX(X): 000-000, 2023-The aim of this study was to investigate the relationship between external workload exposure and changes in countermovement jump force-time characteristics over the course of an entire basketball season, in a sample of National Collegiate Athletic Association Division I, female, basketball players...

PURPOSE: The aim of the present study was to analyze the effect of different eccentric tempos on eccentric kinetics and kinematics and the subsequent concentric performance when performing countermovement jumps against different loads. METHODS: After 1-repetition-maximum assessment and 2 familiarization sessions, 13 well-trained participants performed, in randomized order, 12 sets (4 tempos × 3 loads) of 4 repetitions of the loaded countermovement-jump exercise...

Porous electrodes with high specific surface areas have been commonly employed for alkaline water electrolysis. The gas bubbles generated in electrodes due to water electrolysis, however, can screen the reaction sites and hinder reactant transport, thereby deteriorating the performance of electrodes. Hence, an in-depth understanding of the behavior of bubbles in porous electrodes is of great importance. Nevertheless, since porous electrodes are opaque, direct observation of bubbles therein is still a challenge...

UNLABELLED: Despite previous support for plyometric training, optimal dosing strategies remain unclear. PURPOSE: To investigate vertical and horizontal jump kinetic performance following a low-volume plyometric stimulus with progressively increased session jump volume. METHODS: Sixteen academy rugby players (20.0 [2.0] y; 103.0 [17.6] kg; 184.3 [5.5] cm) volunteered for this study. Vertical and horizontal jump sessions were conducted 1 week apart and consisted of a 40-jump low-volume plyometric stimulus using 4 exercises, after which volume was progressively increased to 200 jumps, using countermovement jump (CMJ) for vertical sessions and horizontal broad jump (HBJ) for horizontal sessions...

Annealing is the process of gradually lowering the temperature of a system to guide it towards its lowest energy states. In an accompanying paper [Y. Luo et al., Phys. Rev. E 108, L052105 (2023)10.1103/PhysRevE.108.L052105], we derived a general bound on annealing performance by connecting annealing with stochastic thermodynamics tools, including a speed limit on state transformation from entropy production. We here describe the derivation of the general bound in detail. In addition, we analyze the case of simulated annealing with Glauber dynamics in depth...

Xu, J, Turner, A, Comyns, TM, Chavda, S, and Bishop, C. The Countermovement rebound jump: between-session reliability and a comparison with the countermovement and drop jump tests. J Strength Cond Res XX(X): 000-000, 2023-The countermovement jump (CMJ) and drop jump (DJ) are widely used jump tests to evaluate an athlete's neuromuscular performance. Nevertheless, conducting both the CMJ and the DJ assessments during one testing session can demand a considerable time investment that practitioners or coaches might not always have available...

Peripheral nerve reconstruction through the employment of nerve guidance conduits with Trichonephila dragline silk as a luminal filling has emerged as an outstanding pre-clinical alternative to avoid nerve autografts. Yet, it remains unknown whether the outcome is similar for silk fibers harvested from other spider species. This study compares the regenerative potential of dragline silk from two orb-weaving spiders, Trichonephila inaurata and Nuctenea umbratica, as well as the silk of the jumping spider Phidippus regius...

Hydraulic jump is a phenomenon that occurs in open channel flow and has wide utility in hydraulic engineering. The present study considered macroroughness features in the bed to improve the characteristics of free and submerged hydraulic jumps. For that, the most often utilized triangular macroroughness elements are contrasted with a distinctive trapezoidal macroroughness. This study implied a numerical model based on computational fluid dynamics (CFD) to investigate the hydraulic jump characteristics over the macroroughness and represented the important features of hydraulic jump such as sequent depth ratio, tail-water depth ratio, longitudinal velocity profile, flow pattern of velocity vector, and contours for turbulent kinetic energy over smooth and macrorough beds...