Effect of Periodic Voluntary Interventions on Trapezius Activation and Fatigue During Light Upper Limb Activity

2021 ◽  
pp. 001872082110507
Author(s):  
Dongwon Kim ◽  
Corine Nicoletti ◽  
Subaryani D. H. Soedirdjo ◽  
Raziyeh Baghi ◽  
Maria-Gabriela Garcia ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Muscle Activation ◽  
Temporal Distribution ◽  
Trapezius Muscle ◽  
Computer Work ◽  
3 Dimensional ◽  
Intervention Activity ◽  
Spatio Temporal ◽  
Voluntary Contractions ◽  
The Impact

Objective The effects of diverse periodic interventions on trapezius muscle fatigue and activity during a full day of computer work were investigated. Background Musculoskeletal disorders, including trapezius myalgia, may be associated with repeated exposure to prolonged low-level activity, even during light upper-extremity tasks including computer work. Methods Thirty healthy adults participated in a study that simulated two 6-hour workdays of computer work. One workday involved imposed periodic passive and active interventions aimed at disrupting trapezius contraction monotony (Intervention day), whereas the other workday did not (Control day). Trapezius muscle activity was quantified by the 3-dimensional acceleration of the jolt movement of the acromion produced by electrically induced muscle twitches. The spatio-temporal distribution of trapezius activity was measured through high-density surface electromyography (HD-EMG). Results The twitch acceleration magnitude in one direction was significantly different across measurement periods ( p = 0.0156) on Control day, whereas no significant differences in any direction were observed ( p > 0.05) on Intervention day. The HD-EMG from Intervention day showed that only significant voluntary muscle contractions (swing arms, Jacobson maneuver) induced a decrease in the muscle activation time and an increase in the spatial muscle activation areas ( p < 0.01). Conclusion Disruption of trapezius monotonous activity via brief voluntary contractions effectively modified the ensuing contraction pattern (twitch acceleration along one axis, active epochs reduction, and larger spatial distribution). The observed changes support an associated reduction of muscle fatigue. Application This study suggests that disruptive intervention activity is efficient in reducing the impact of trapezius muscle fatigue.

scholarly journals On the Effect of Red Sea and Topography on Rainfall over Saudi Arabia: Case Study

Atmosphere ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 669
Author(s):  
Al-Mutairi ◽  
Abdel Basset ◽  
Morsy ◽  
Abdeldym
Keyword(s):  
Saudi Arabia ◽  
Red Sea ◽  
Sea Water ◽  
Wrf Model ◽  
Temporal Distribution ◽  
Surface Fluxes ◽  
Sensitivity Experiment ◽  
Low Level ◽  
Spatio Temporal ◽  
The Impact

This paper aimed to investigate the impact of Red Sea topography and water on the development and rainfall of a case of cyclogenesis occurs over Saudi Arabia during the period 16–18 November 2015 using the Weather Research and Forecasting (WRF) model. The WRF Control Run (WRF-CR) experiment was performed with presence of actual topography and surface water of the Red Sea, while the other three sensitivity experiments were carried out without (i) Red Sea Topography (NRST), (ii) Red Sea Water (NRSW), and (iii) Red Sea Topography and Water (NRSTW). The simulated rainfall in the control experiment depicts in well agreement with Tropical Rainfall Measurement Mission (TRMM) rainfall estimates in terms of intensity as well as spatio-temporal distribution. Results demonstrate that rainfall intensity and spatio-temporal distribution significantly changes through each sensitivity experiment compared to the WRF-CR, where the significant variation was found in the NRST experiment. The absence of topography (NRST) leads to formation of strong convergence area over the middle of Red Sea which enhanced uplift motion that further strengthened the low-level jet over Red Sea and the surrounding regions, which enhanced the moisture and temperature gradient and created a conditionally unstable atmosphere that favored the development of the cyclonic system. The absence of Red Sea water (NRSW) changed rainfall spatial distribution and reduced its amount by about 30–40% due to affecting of the dynamics of the upward motion and moisture gradient, suggesting that surface fluxes play an important role in regulating the low-level moist air convergence prior to convection initiation and development.

scholarly journals Quadriceps Muscle Fatigue Reduces Extension and Flexion Power During Maximal Cycling

2022 ◽  
Vol 3 ◽  
Author(s):  
Steven J. O'Bryan ◽  
Janet L. Taylor ◽  
Jessica M. D'Amico ◽  
David M. Rouffet
Keyword(s):  
Muscle Fatigue ◽  
Muscle Activation ◽  
Power Production ◽  
Quadriceps Muscle ◽  
Individual Variability ◽  
Voluntary Activation ◽  
Peripheral Fatigue ◽  
Emg Activity ◽  
Pedal Force ◽  
Voluntary Contractions

Purpose: To investigate how quadriceps muscle fatigue affects power production over the extension and flexion phases and muscle activation during maximal cycling.Methods: Ten participants performed 10-s maximal cycling efforts without fatigue and after 120 bilateral maximal concentric contractions of the quadriceps muscles. Extension power, flexion power and electromyographic (EMG) activity were compared between maximal cycling trials. We also investigated the associations between changes in quadriceps force during isometric maximal voluntary contractions (IMVC) and power output (flexion and extension) during maximal cycling, in addition to inter-individual variability in muscle activation and pedal force profiles.Results: Quadriceps IMVC (−52 ± 21%, P = 0.002), voluntary activation (−24 ± 14%, P &lt; 0.001) and resting twitch amplitude (−45 ± 19%, P = 0.002) were reduced following the fatiguing task, whereas vastus lateralis (P = 0.58) and vastus medialis (P = 0.15) M-wave amplitudes were unchanged. The reductions in extension power (−15 ± 8%, P &lt; 0.001) and flexion power (−24 ± 18%, P &lt; 0.001) recorded during maximal cycling with fatigue of the quadriceps were dissociated from the decreases in quadriceps IMVC. Peak EMG decreased across all muscles while inter-individual variability in pedal force and EMG profiles increased during maximal cycling with quadriceps fatigue.Conclusion: Quadriceps fatigue induced by voluntary contractions led to reduced activation of all lower limb muscles, increased inter-individual variability and decreased power production during maximal cycling. Interestingly, power production was further reduced over the flexion phase (24%) than the extension phase (15%), likely due to larger levels of peripheral fatigue developed in RF muscle and/or a higher contribution of the quadriceps muscle to flexion power production compared to extension power during maximal cycling.

Mental stress and trapezius muscle activation under psychomotor challenge: A focus on EMG gaps during computer work

2008 ◽  
Vol 45 (3) ◽  
pp. 356-365 ◽  
Author(s):  
Lawrence M. Schleifer ◽  
Thomas W. Spalding ◽  
Scott E. Kerick ◽  
Jeffrey R. Cram ◽  
Ronald Ley ◽  
...  
Keyword(s):  
Mental Stress ◽  
Muscle Activation ◽  
Trapezius Muscle ◽  
Computer Work ◽  
Emg Gaps

scholarly journals Spatio-Temporal Visualisation of Reflections from Building Integrated Photovoltaics

2018 ◽  
Author(s):  
Roland Schregle ◽  
Christian Renken ◽  
Stephen Wittkopf
Keyword(s):  
Reference Material ◽  
Distribution Functions ◽  
High Temporal Resolution ◽  
Complex Data ◽  
3 Dimensional ◽  
Building Integrated Photovoltaics ◽  
Computational Workflow ◽  
Spatio Temporal ◽  
The Impact

With the increasing adoption of building integrated photovoltaics (BIPV), concerns arise about potential glare. While recommended criteria to assess glare exist, it is challenging to apply these in the spatial and temporal domains and communicate the complex data to planning authorities and clients. In this paper we present a new computational workflow using annual daylight simulation, material modelling using bi-directional scattering distribution functions (BSDFs) and image-based postprocessing to obtain 3-dimensional renderings of cumulative annual irradiance and glare duration on the built environment. The annual daylight simulation considers relevant sun positions in high temporal resolution (15-minute timesteps) and measured BSDFs to model different PV materials. The postprocessing includes a relative irradiance visualisation comparing the impact of a proposed PV proportional to a reference material. It also includes a new spatio-temporal workflow to assess the glare duration based on recommended thresholds. We demonstrate this workflow with a case study of a proposed PV roof for a church, assessing the glare potential of two different PV materials. Our visualisations indicate glare durations well below the thresholds with satinated PVs, and in noncritical zones outside observer positions with standard PVs. Thus the proposed PV roof does not cause any disturbing glare.

scholarly journals Spatio-Temporal Visualisation of Reflections from Building Integrated Photovoltaics

2018 ◽  
Author(s):  
Roland Schregle ◽  
Christian Renken ◽  
Stephen Wittkopf
Keyword(s):  
Reference Material ◽  
Distribution Functions ◽  
High Temporal Resolution ◽  
Complex Data ◽  
3 Dimensional ◽  
Building Integrated Photovoltaics ◽  
Computational Workflow ◽  
Spatio Temporal ◽  
The Impact

With the increasing adoption of building integrated photovoltaics (BIPV), concerns arise about potential glare. While recommended criteria to assess glare exist, it is challenging to apply these in the spatial and temporal domains and communicate the complex data to planning authorities and clients. This paper presents a new computational workflow using annual daylight simulation, material modelling using bi-directional scattering distribution functions (BSDFs) and image-based postprocessing to obtain 3-dimensional renderings of cumulative annual irradiance and glare duration on the built environment. The annual daylight simulation considers relevant sun positions in high temporal resolution (15-minute timesteps) and measured BSDFs to model different PV materials. The postprocessing includes a relative irradiance visualisation comparing the impact of a proposed PV proportional to a reference material. It also includes a new spatio-temporal workflow to assess the glare duration based on recommended thresholds. This workflow is demonstrated with a case study of a proposed PV roof for a church, assessing the glare potential of two different PV materials. The visualisations indicate glare durations well below the thresholds with satinated PVs, and in noncritical zones outside observer positions with standard PVs. Thus the proposed PV roof does not cause any disturbing glare.

Snow Cover Dynamics and its Spatio-Temporal Distribution in the Central Higher Himalaya of India

2021 ◽  
Vol 14 (9) ◽  
pp. 15-22
Author(s):  
Masoom Reza ◽  
Ramesh Chandra Joshi
Keyword(s):  
Climate Change ◽  
Snow Cover ◽  
Geographical Area ◽  
Temporal Distribution ◽  
Melting Rate ◽  
Optical Data ◽  
Snow Cover Area ◽  
Central Himalayas ◽  
Spatio Temporal ◽  
The Impact

Retreating glaciers, changing timber line and decreasing accumulation of snow in the Himalaya are considered the indicators of climate change. In this study, an attempt is made to observe the snow cover change in the higher reaches of the Central Himalayas. Investigation of climate change through snow cover is very important to understand the impact and adaptation in an area. Landsat thematic and multi spectral optical data with a spatial resolution of 60m and 30m are considered for the estimation and extraction of snow cover. Total 3,369 Km2 snow cover area is lost since 1972 out of total geographical area i.e. 17,227 Km2. The accumulation of snow during winter is lower than the melting rate during summer. The current study identified the decrease of 19.6 % snow cover in 47 years since 1972 to 2019. Composite satellite imageries of September to December show that the major part of the study area covered with snow lies above 3600m. Overall observation indicates that in 47 years, permanent snow cover is decreasing in Central Himalayas.

scholarly journals Spatio-Temporal Visualisation of Reflections from Building Integrated Photovoltaics

Buildings ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 101 ◽  
Author(s):  
Roland Schregle ◽  
Christian Renken ◽  
Stephen Wittkopf
Keyword(s):  
Reference Material ◽  
Distribution Functions ◽  
High Temporal Resolution ◽  
Complex Data ◽  
3 Dimensional ◽  
Building Integrated Photovoltaics ◽  
Computational Workflow ◽  
Spatio Temporal ◽  
The Impact

With the increasing adoption of building integrated photovoltaics (BIPV), concerns arise about potential glare. While recommended criteria to assess glare exist, it is challenging to apply these in the spatial and temporal domains and communicate the complex data to planning authorities and clients. This paper presents a new computational workflow using annual daylight simulation, material modelling using bi-directional scattering distribution functions (BSDFs) and image-based postprocessing to obtain 3-dimensional renderings of cumulative annual irradiance and glare duration on the built environment. The annual daylight simulation considers relevant sun positions in high temporal resolution (15-min timesteps) and measured BSDFs to model different PV materials. The postprocessing includes a relative irradiance visualisation comparing the impact of a proposed PV proportional to a reference material. It also includes a new spatio-temporal workflow to assess the glare duration based on recommended thresholds. This workflow is demonstrated with a case study of a proposed PV roof for a church, assessing the glare potential of two different PV materials. The visualisations indicate glare durations well below the thresholds with satinated PVs, and in noncritical zones outside observer positions with standard PVs. Thus the proposed PV roof does not cause any disturbing glare.

scholarly journals Moisture recycling over the Iberian Peninsula. The impact of 3DVAR data assimilation

2020 ◽  
Author(s):  
Santos J. González-Rojí ◽  
Jon Sáenz ◽  
Javier Díaz de Argandoña ◽  
Gabriel Ibarra-Berastegi
Keyword(s):  
Soil Moisture ◽  
Data Assimilation ◽  
Iberian Peninsula ◽  
Wrf Model ◽  
Temporal Distribution ◽  
Horizontal Resolution ◽  
Moisture Recycling ◽  
Weather Observations ◽  
Spatio Temporal ◽  
The Impact

&lt;p&gt;The moisture recycling is defined as the fraction of precipitation over a delimited region that comes from the evaporation over that region. Its importance lies in the fact that it is an approximated measurement of a regional feedback between the atmosphere and the surface. Thus, this study estimates the spatio-temporal distribution of moisture recycling over the Iberian Peninsula (IP), and focuses on the impact of the use of 3DVAR data assimilation during the modeling stage.&lt;/p&gt;&lt;p&gt;For that purpose, two different simulations were run using the Weather and Research Forecasting (WRF) model with a horizontal resolution of 15 km over the IP. The first simulation (WRF N) was nested inside ERA-Interim as usual in numerical downscaling exercises, with information passed to the domain through the boundaries. The second run (WRF D) presents the same configuration as WRF N, but it also includes 3DVAR data assimilation step every six hours (at 00, 06, 12 and 18 UTC). Sea surface temperature was updated daily, and observations in PREPBUFR format included in the NCEP ADP Global Upper Air and Surface Weather Observations dataset were used for the data assimilation step. Only those inside a 120-minute window centered at the analysis times were assimilated. Both simulations cover the period 2010-2014, but the experiment WRF D was extended later until 2018.&lt;/p&gt;&lt;p&gt;The lowest values of moisture recycling (around 3 %) are obtained from November to February, while the most remarkable values are observed in spring (around 16 %) in both simulations. The moisture recycling is confined to the southeastern corner of the IP during winter. However, during spring and summer, a gradient of higher values towards the northeastern corner of the IP are observed in both simulations. The differences between simulations, associated to the dryness of the soil in the model, are highlighted during summer and autumn. WRF D presents a lower bias and produces more reliable results because of a better representation of the atmospheric moisture.&lt;/p&gt;&lt;p&gt;A Cross-Correlation Function (CCF) based analysis was performed for each combination of moisture recycling, accumulated precipitation and mean soil moisture over the IP. For the common period (2010-2014), the results show that the WRF D experiment extends the lifespan of moisture over the IP. The CCF analysis for soil moisture against precipitation also shows an unphysical negative lag (-1 month) for WRF N, whilst for WRF D both variables are simultaneous. For the extended WRF D simulation (2010-2018), it was found that the delay between precipitation and moisture recycling over the IP is five months.&lt;/p&gt;

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