scholarly journals Evidence for Muscle Cell-Based Mechanisms of Enhanced Performance in Stretch-Shortening Cycle in Skeletal Muscle

2021 ◽  
Vol 11 ◽  
Author(s):  
Atsuki Fukutani ◽  
Tadao Isaka ◽  
Walter Herzog
Keyword(s):  
Skeletal Muscle ◽  
Energy Storage ◽  
Stretch Reflex ◽  
Human Movement ◽  
Eccentric Contraction ◽  
Human Movements ◽  
Reflex Activation ◽  
Stretch Shortening Cycle ◽  
Residual Force Enhancement ◽  
And Storage

Force attained during concentric contraction (active shortening) is transiently enhanced following eccentric contraction (active stretch) in skeletal muscle. This phenomenon is called stretch-shortening cycle (SSC) effect. Since many human movements contain combinations of eccentric and concentric contractions, a better understanding of the mechanisms underlying the SSC effect would be useful for improving physical performance, optimizing human movement efficiency, and providing an understanding of fundamental mechanism of muscle force control. Currently, the most common mechanisms proposed for the SSC effect are (i) stretch-reflex activation and (ii) storage of energy in tendons. However, abundant SSC effects have been observed in single fiber preparations where stretch-reflex activation is eliminated and storage of energy in tendons is minimal at best. Therefore, it seems prudent to hypothesize that factor(s) other than stretch-reflex activation and energy storage in tendons contribute to the SSC effect. In this brief review, we focus on possible candidate mechanisms for the SSC effect, that is, pre-activation, cross-bridge kinetics, and residual force enhancement (RFE) obtained in experimental preparations that exclude/control the influence of stretch-reflex activation and energy storage in tendons. Recent evidence supports the contribution of these factors to the mechanism of SSCs, and suggests that the extent of their contribution varies depending on the contractile conditions. Evidence for and against alternative mechanisms are introduced and discussed, and unresolved problems are mentioned for inspiring future studies in this field of research.

scholarly journals Ensemble model for estimating continental-scale patterns of human movement: a case study of Australia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Karen McCulloch ◽  
Nick Golding ◽  
Jodie McVernon ◽  
Sarah Goodwin ◽  
Martin Tomko
Keyword(s):  
Spatial Scales ◽  
Predictive Ability ◽  
Movement Patterns ◽  
Human Movement ◽  
Continental Scale ◽  
Movement Characteristics ◽  
Human Movements ◽  
Movement Models ◽  
Epidemiology Data

AbstractUnderstanding human movement patterns at local, national and international scales is critical in a range of fields, including transportation, logistics and epidemiology. Data on human movement is increasingly available, and when combined with statistical models, enables predictions of movement patterns across broad regions. Movement characteristics, however, strongly depend on the scale and type of movement captured for a given study. The models that have so far been proposed for human movement are best suited to specific spatial scales and types of movement. Selecting both the scale of data collection, and the appropriate model for the data remains a key challenge in predicting human movements. We used two different data sources on human movement in Australia, at different spatial scales, to train a range of statistical movement models and evaluate their ability to predict movement patterns for each data type and scale. Whilst the five commonly-used movement models we evaluated varied markedly between datasets in their predictive ability, we show that an ensemble modelling approach that combines the predictions of these models consistently outperformed all individual models against hold-out data.

scholarly journals Photodoping of metal oxide nanocrystals for multi-charge accumulation and light-driven energy storage

Nanoscale ◽  
2021 ◽  
Author(s):  
Michele Ghini ◽  
Nicola Curreli ◽  
Andrea Camellini ◽  
Mengjiao Wang ◽  
Aswin Asaithambi ◽  
...  
Keyword(s):  
Energy Storage ◽  
Solar Energy ◽  
Metal Oxide ◽  
Direct Conversion ◽  
Charge Accumulation ◽  
Innovative Solutions ◽  
And Storage ◽  
The Way

Light-driven multi-charge accumulation (i.e., photodoping) of doped metal oxide nanocrystals opens the way to innovative solutions for the direct conversion and storage of the solar energy.

Design and Research of Integrated PV and Storage Grid-Connected Generation System

2014 ◽  
Vol 1070-1072 ◽  
pp. 24-29
Author(s):  
Xiao Di Qin ◽  
Rong Rong Zhou ◽  
Lie Xia ◽  
Liang Hui Xu
Keyword(s):  
Energy Storage ◽  
System Integration ◽  
Tracking System ◽  
Storage System ◽  
Energy Storage System ◽  
Vanadium Redox Flow Battery ◽  
Generation System ◽  
Pv System ◽  
Design Scheme ◽  
And Storage

Based on practical project and application, the design scheme of small capacity of integrated PV and storage grid-connected generation system is presented in this paper. For demonstrative and experimental purpose in this project, it includes several typical PV modules, tracking system and grid-connected inverters. Entire design scheme covers system integration, grid-connected solution, PV array and bracket, monitoring system, energy storage system, and etc. Configuration and application prospect of energy storage system in grid-connected PV system are mainly introduced. The characteristics of lithium battery and vanadium redox flow battery, as well as their application in the field of distributed power generation are researched.

Energy Storage Using Low-Pressure Feedwater

1985 ◽  
Vol 107 (3) ◽  
pp. 569-573 ◽  
Author(s):  
C. M. Harman ◽  
S. Loesch
Keyword(s):  
Energy Storage ◽  
Power Plants ◽  
Storage System ◽  
Energy Storage System ◽  
Low Pressure ◽  
Steam Power ◽  
Low Pressure Turbine ◽  
Availability Analysis ◽  
Steam Power Plants ◽  
And Storage

A method for increasing the peak output of steam power plants through use of a low-pressure feedwater storage system is presented. The generalized availability analysis involves only the low-pressure turbine, low-pressure feedwater heaters, and the storage system. With daily cycling and storage charging at near base load conditions, the turnaround efficiency of the energy storage system was found to approach 100 percent. Storage system turnaround efficiency is decreased when the energy is stored during plant part-load operation.

Evaluation of Commercial Building Clusters With Energy Storage to Reduce Reliance on Electrical Utility Grids

2021 ◽  
Author(s):  
Gregory Kaminski ◽  
Philip Odonkor
Keyword(s):  
Energy Storage ◽  
Storage Systems ◽  
Storage System ◽  
Energy Resource ◽  
Energy Resources ◽  
Distributed Energy Resources ◽  
Commercial Building ◽  
Distributed Energy ◽  
Distributed Resources ◽  
And Storage

Abstract The decreasing cost of implementation and increasing regulatory incentive to lower energy use have led to an increased adoption of distributed energy resources in recent years. This increased adoption has been further fueled by a surge in energy consciousness and the expansion of energy-saving products and technologies. To lower reliance on the electrical grid and fully realize the benefits of distributed energy resources, many consumers have also elected to use battery systems to store generated energy. For owners of multiple buildings, or multiple owners willing to share the operational cost, building clusters may be formed to more effectively take advantage of these distributed resources and storage systems. The implementation of these systems in existing buildings introduces the question of what makes a “good” building cluster. Furthermore, the scalable nature of distributed energy sources and storage systems create countless possibilities for system configuration. Through comparison of unique two-building clusters from a stock of five buildings with a given distributed energy resource (in this case, a solar photovoltaic panel array) and energy storage system, we develop a fundamental understanding of the underlying factors that allow building clusters to be less reliant on the utility grid and make better use of energy generation and storage systems.

Differential effects of anesthetics on in vivo skeletal muscle contractile function in the mouse

1996 ◽  
Vol 80 (1) ◽  
pp. 332-340 ◽  
Author(s):  
C. P. Ingalls ◽  
G. L. Warren ◽  
D. A. Lowe ◽  
D. B. Boorstein ◽  
R. B. Armstrong
Keyword(s):  
Skeletal Muscle ◽  
Contractile Function ◽  
Average Power ◽  
Eccentric Contraction ◽  
Peak Torque ◽  
High Dose ◽  
Skeletal Muscle Function ◽  
Contractile Responses ◽  
Time Integral

The purpose of this study was to evaluate the effects of four anesthetic regimens on in vivo contractile function of mouse ankle dorsiflexor muscles. The torque-frequency and torque-velocity relationships were determined for the following anesthetics: fentanyl-droperidol and diazepam (F-d/d); ketamine and xylazine (K/x); pentobarbital sodium (Ps); and methoxyflurane (Mf). Mf, Ps, and F-d/d regimens resulted in comparable contractile responses at low doses, whereas K/x produced a relative depression in isometric contractile function as shown by a decrease in the torque-time integral at the 300-Hz stimulation frequency (-13.9%; P < 0.05). Moreover, K/x caused a shift to the left in the torque-frequency curve as indicated by increases in torque-time integrals at 25 and 50 Hz. Both Ps and F-d/d regimens exhibited dose-dependent effects during the isovelocity contractions. Ps significantly reduced work (-28.7%) and average power (-28.9%) at 800 degrees/s at the high dose. In contrast, F-d/d anesthesia resulted in increases in peak torque (16-20%) and work (15-18%) output at all eccentric contraction velocities at the high dose, whereas average power was increased only at -800 (17%) and -1,000 degrees/s (17%). In conclusion, commonly used anesthetic regimens can affect the contractile response in vivo; K/x and Ps yield smaller torque outputs, whereas Mf and F-d/d consistently produce larger contractile responses. Mf and F-d/d are recommended for use in studying skeletal muscle function in mice in vivo.

scholarly journals Isometric resistance training increases strength and alters histopathology of dystrophin-deficient mouse skeletal muscle

2019 ◽  
Vol 126 (2) ◽  
pp. 363-375 ◽  
Author(s):  
Angus Lindsay ◽  
Alexie A. Larson ◽  
Mayank Verma ◽  
James M. Ervasti ◽  
Dawn A. Lowe
Keyword(s):  
Skeletal Muscle ◽  
Muscular Dystrophy ◽  
Muscle Strength ◽  
Exercise Training ◽  
Satellite Cells ◽  
Eccentric Contraction ◽  
Deficient Mouse ◽  
Isometric Training ◽  
Isometric Torque ◽  
Edl Muscle

Mutation to the dystrophin gene causes skeletal muscle weakness in patients with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD). Deliberation continues regarding implications of prescribing exercise for these patients. The purpose of this study was to determine whether isometric resistance exercise (~10 tetanic contractions/session) improves skeletal muscle strength and histopathology in the mdx mouse model of DMD. Three isometric training sessions increased in vivo isometric torque (22%) and contractility rates (54%) of anterior crural muscles of mdx mice. Mice expressing a BMD-causing missense mutated dystrophin on the mdx background showed comparable increases in torque (22%), while wild-type mice showed less change (11%). Increases in muscle function occurred within 1 h and peaked 3 days posttraining; however, the adaptation was lost after 7 days unless retrained. Six isometric training sessions over 4 wk caused increased isometric torque (28%) and contractility rates (22–28%), reduced fibrosis, as well as greater uniformity of fiber cross-sectional areas, fewer embryonic myosin heavy-chain-positive fibers, and more satellite cells in tibialis anterior muscle compared with the contralateral untrained muscle. Ex vivo functional analysis of isolated extensor digitorum longus (EDL) muscle from the trained hindlimb revealed greater absolute isometric force, lower passive stiffness, and a lower susceptibility to eccentric contraction-induced force loss compared with untrained EDL muscle. Overall, these data support the concept that exercise training in the form of isometric tetanic contractions can improve contractile function of dystrophin-deficient muscle, indicating a potential role for enhancing muscle strength in patients with DMD and BMD. NEW & NOTEWORTHY We focused on adaptive responses of dystrophin-deficient mouse skeletal muscle to isometric contraction training and report that in the absence of dystrophin (or in the presence of a mutated dystrophin), strength and muscle histopathology are improved. Results suggest that the strength gains are associated with fiber hypertrophy, reduced fibrosis, increased number of satellite cells, and blunted eccentric contraction-induced force loss in vitro. Importantly, there was no indication that the isometric exercise training was deleterious to dystrophin-deficient muscle.

scholarly journals Solar Tower Power Plants of Molten Salt External Receivers in Algeria: Analysis of Direct Normal Irradiation on Performance

2018 ◽  
Vol 8 (8) ◽  
pp. 1221 ◽  
Author(s):  
Abdelkader Rouibah ◽  
Djamel Benazzouz ◽  
Rahmani Kouider ◽  
Awf Al-Kassir ◽  
Justo García-Sanz-Calcedo ◽  
...  
Keyword(s):  
Power Generation ◽  
Energy Storage ◽  
Thermal Energy ◽  
Greenhouse Effect ◽  
Energy Production ◽  
Power Plants ◽  
Storage Capacity ◽  
Real Data ◽  
Multiple Power ◽  
And Storage

The increase of solar energy production has become a solution to meet the demand of electricity and reduce the greenhouse effect worldwide. This paper aims to determine the performance and viability of direct normal irradiation of three solar tower power plants in Algeria, to be installed in the highlands and the Sahara (Béchar, El Oued, and Djelfa regions). The performance of the plants was obtained through a system advisor model simulator. It used real data gathered from appropriate meteorological files. A relationship between the solar multiple (SM), power generation, and thermal energy storage (TES) hours was observed. The results showed that the optimal heliostat field corresponds to 1.8 SM and 2 TES hours in Béchar, 1.2 SM and 2 TES hours for El Oued, and 1.5 SM and 4 TES hours for Djelfa. This study shows that there is an interesting relationship between the solar multiple, power generation, and storage capacity.

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