Substrate rigidity modulates traction forces and stoichiometry of cell matrix adhesions.

In cell matrix adhesions, integrin receptors and associated proteins provide a dynamic coupling of the extracellular matrix (ECM) to the cytoskeleton. This allows bidirectional transmission of forces between the ECM and the cytoskeleton, which tunes intracellular signaling cascades that control survival, proliferation, differentiation, and motility. The quantitative relationships between recruitment of distinct cell matrix adhesion proteins and local cellular traction forces are not known. Here, we applied quantitative superresolution microscopy to cell matrix adhesions formed on fibronectin-stamped elastomeric pillars and developed an approach to relate the number of talin, vinculin, paxillin, and focal adhesion kinase (FAK) molecules to the local cellular traction force. We find that FAK recruitment does not show an association with traction-force application whereas a ~60 pN force increase is associated with the recruitment of one talin, two vinculin, and two paxillin molecules on a substrate of effective stiffness of 47 kPa. On a substrate with a four-fold lower effective stiffness the stoichiometry of talin:vinculin:paxillin changes to 2:12:6 for the same ~60 pN traction force. The relative change in force-related vinculin recruitment indicates a stiffness-dependent switch in vinculin function in cell matrix adhesions. Our results reveal a substrate-stiffness-dependent modulation of the relation between cellular traction-force and the molecular stoichiometry of cell-matrix adhesions.

Modeling the influence of intellectual potential on innovative development of PAO Aeroflot – Russian Airlines

Subject. The article investigates the innovative development of Aeroflot Group and analyzes the impact of factors of intellectual potential. Objectives. The purpose is to investigate the development of intellectual potential of Aeroflot Group by selected indicators, determine their impact on the innovative development of the company, and increase its competitiveness. Methods. We studied the works of Russian and foreign scientists, performed a regression analysis and econometric modeling on the basis of statistical data from the annual reports of Aeroflot Group for 2005–2020. To create econometric models, we applied the tools of the EViews 12 software package. Results. We built econometric models to study and forecast the innovative development of Aeroflot Group, given the influence of intellectual potential factors. The analysis of these models showed that the linear model is adequate and can be used in the practical activities of Aeroflot Group. The exponential model parameters and estimates proved to be insignificant, so it cannot be used for the research. Conclusions. The long-term economic growth of the country and its innovative development depend directly on such factors of intellectual potential as human capital, personnel skills (number and quality of labor force), increase in expertise and labor productivity, availability of social incentives. Therefore, the focus of national projects implementation in Russia is on accelerated innovative development of the country, using the factors of intellectual potential of enterprises and creating conditions for the growth of its quality and social incentives.

Frank-Starling mechanism, fluid responsiveness, and length-dependent activation: Unravelling the multiscale behaviors with an in silico analysis

The Frank-Starling mechanism is a fundamental regulatory property which underlies the cardiac output adaptation to venous filling. Length-dependent activation is generally assumed to be the cellular origin of this mechanism. At the heart scale, it is commonly admitted that an increase in preload (ventricular filling) leads to an increased cellular force and an increased volume of ejected blood. This explanation also forms the basis for vascular filling therapy. It is actually difficult to unravel the exact nature of the relationship between length-dependent activation and the Frank-Starling mechanism, as three different scales (cellular, ventricular and cardiovascular) are involved. Mathematical models are powerful tools to overcome these limitations. In this study, we use a multiscale model of the cardiovascular system to untangle the three concepts (length-dependent activation, Frank-Starling, and vascular filling). We first show that length-dependent activation is required to observe both the Frank-Starling mechanism and a positive response to high vascular fillings. Our results reveal a dynamical length dependent activation-driven response to changes in preload, which involves interactions between the cellular, ventricular and cardiovascular levels and thus highlights fundamentally multiscale behaviors. We show however that the cellular force increase is not enough to explain the cardiac response to rapid changes in preload. We also show that the absence of fluid responsiveness is not related to a saturating Frank-Starling effect. As it is challenging to study those multiscale phenomena experimentally, this computational approach contributes to a more comprehensive knowledge of the sophisticated length-dependent properties of cardiac muscle.

Theoretical Investigation of the Adsorption of Cadmium Iodide from Water Using Polyaniline Polymer Filled with TiO2 and ZnO Nanoparticles

The removal of heavy metals from drinking water has attracted great interest in water purification technology. In this study, a biocompatible Polyaniline (PANI) polymer filled with TiO2 and ZnO nanoparticles (NPs) is considered as an adsorbent of cadmium iodide from water. Theoretical investigation of the van der Waals (vdW) interactions deduced from the Hamaker constant calculated on the basis of Lifshitz theory was presented. It was found that the surface energy as well as the work of adhesion between water and PANI/NPs across air increases with an increasing volume fraction of the TiO2 and ZnO nanoparticles. Consequently, an increase in the Laplace pressure around the cavities/porosities was found, which leads to the enhancement of the specific contact surface between water and PANI/NPs. On the other hand, for the interactions between CdI2 particles and PANI/NPs surface across water, we show that the interactions are governed principally by the attractive London dispersion forces. The vdW energy and force increase proportionally with the augmentation of the volume fraction of nanoparticles and of the radius of the CdI2 particle. Particularly, the PANI/TiO2 has been proved to be a better candidate for adsorption of cadmium iodide from water than PANI/ZnO.

Do It Yourself: Air Drag Force Experiment Using Paper and Scraper Sheet

Free fall motion in air medium is only influenced by gravitation acceleration. However, there are several variables that caused the observations to be different with the concept. Variables, such as air drag and terminal velocity, are often teachers not presented in detail, causing misconceptions. This study aims to develop a simple experiment on free fall motion by identifying air drag and terminal velocity. The data in this study is the video of free fall motion of paper and scraper analyzed using Tracker video analyze. From the video analyzed, information is obtained in the form of time (t), track (l, θ), and velocity (v) of the object. This study shows that the air drag force increase unto the terminal velocity. The calculation of the drag coefficient giving the number of the paper 2,16 and the scraper 2,10. According to data analyzed, the air drag force is affected by the mass (m), area (A), and the air drag force (F_D) with the linear correlation until it reaches the terminal velocity. The result of this study may use as references of free fall motion experiment with other objects and analyze.

Disgusting odours affect the characteristics of the Adaptive Force in contrast to neutral and pleasant odours

The olfactomotor system is especially investigated by examining the sniffing in reaction to olfactory stimuli. The motor output of respiratory-independent muscles was seldomly considered regarding possible influences of smells. The Adaptive Force (AF) characterizes the capability of the neuromuscular system to adapt to external forces in a holding manner and was suggested to be more vulnerable to possible interfering stimuli due to the underlying complex control processes. The aim of this pilot study was to measure the effects of olfactory inputs on the AF of the hip and elbow flexors, respectively. The AF of 10 subjects was examined manually by experienced testers while smelling at sniffing sticks with neutral, pleasant or disgusting odours. The reaction force and the limb position were recorded by a handheld device. The results show, inter alia, a significantly lower maximal isometric AF and a significantly higher AF at the onset of oscillations by perceiving disgusting odours compared to pleasant or neutral odours (p < 0.001). The adaptive holding capacity seems to reflect the functionality of the neuromuscular control, which can be impaired by disgusting olfactory inputs. An undisturbed functioning neuromuscular system appears to be characterized by a proper length tension control and by an earlier onset of mutual oscillations during an external force increase. This highlights the strong connection of olfaction and motor control also regarding respiratory-independent muscles.

Muscle Fatigue When Riding a Motorcycle: A Case Study

This case study was conducted to assess muscle pattern, as measured by surface electromyography (sEMG), and its changes during a controlled superbike closed-road track training session. The sEMG signals were recorded unilaterally from biceps brachii (BB), triceps brachii (TB), anterior and posterior part of the deltoid (DA and DP respectively), flexor digitorum superficialis (FS), extensor carpi radialis (CR), extensor digitorum communis (ED) and pectoralis major (PM) during three rounds of 30 min. sEMG signals selected for analysis came from the beginning of the braking action to the way-out of the curves of interest. Considering the laps and rounds as a whole and focusing on the forearm muscles, ED was more systematically (84%) assigned to a state of fatigue than FS (44%) and CR (39%). On the opposite, the TB and DP muscles showed a predominant state of force increase (72%). Whereas the BB showed alternatively a state of fatigue or force increase depending on the side of the curve, when taking into account only the sharpest curves, it showed a predominant state of force increase. In conclusion, the fact that forearm muscles must endure a long-lasting maintenance of considerable activity levels explains why they easily got into a state of fatigue. Moreover, TB and DA are particularly relevant when cornering.

Effect of a toe-walking protocol in plantar heel pain: A pilot study

Introduction/Purpose: Plantar heel pain (PHP) is one of most common disorders of the foot treated in primary care. It affects athletic and sedentary populations, with patient reports of activity-limiting pain and reduced quality of life. Recently, atrophy of the forefoot plantar intrinsic musculature was identified in patients with PHP.Therefore, the purpose of this study was to assess whether loading the plantar fascia strengthens the intrinsic foot musculature (IFM) and decreases PHP sufferers’ symptoms.Methods: A within-subjects experimental design assessed Foot Function Index (FFI) and IFM strength via hand-held dynamometry (HHD) in 12 patients with PHP prior to and at the end of a six-week toe-walking program.Results: After six weeks of treatment, the mean (SD) FFI score significantly decreased from 73.2 (32.4) to 43.3 (22.8) points (p = 0.010, ES = 1.1). HHD measures: Both great toe flexion and lesser toes flexion strength measures demonstrated significant force increase of 7.8N 95%CI [1.3, 14.4] (p = 0.024, ES = 1.0) and 6.6N 95%CI [1.8, 11.4] (p = 0.010, ES = 0.9), respectively.Conclusion: Results suggest toe-walking reduces PHP symptoms and increases IFM strength. There was no identified correlation between the IFM and FFI changes. Symptom reduction may potentially be due to a reduction in cortical inhibition rather than IFM strength changes. Findings provide foundation for future studies, employing imaging, to further validate the effectiveness of toe-walking in reducing symptoms of PHP patients.Trial registration: PROSPERO 2016 CRD42016036302 Registered 10 March 2016, https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42016036302

Changes and Differences in Body Composition and Strength Abilities of Athletes in Fitness and Bodybuilding at Different Intervals of Rest

The paper deals with changes in body composition (muscle mass, adipose tissue and bone mass), and changes in manifestations of maximal strength of extensors and flexors of lower and upper limbs in relation to different periods of rest (30 s, 60 s, 120 s). The research was carried out on 23 participants aged 18-30 years in natural bodybuilders of top performance, in a 5-week training intervention of bodybuilding training.At a statistical significance level of 5%, there was no significant difference in muscle tissue hypertrophy, although Group 2 (60 p.) Achieved a two-fold increase in percentage FFM compared to the other two groups, achieving a change of 1.18 %.At a statistical significance level of 5%, we noticed significant differences in the maximum force increase in knee joint flexors, and only in group 3 (120 s) by up to 11%. Significant differences in muscle strength increase were also observed in groups 2 and 3 in the elbow joint extensors and in the elbow joint flexors only in group 1.

Motor control and olfaction – Influence of pleasant and disgusting odors on the Adaptive Force

The Adaptive Force (AF) characterizes the capability of the neuromuscular system to adapt to external forces. The aim was to measure the effects of different olfactory inputs on the AF of the hip and elbow flexors, respectively. The AF of 10 subjects was examined manually by experienced testers while smelling at sniffing sticks with neutral, pleasant or disgusting odors. The reaction force and the position of the tested limb were recorded by a handheld device. The results show, inter alia, a significantly lower maximal isometric AF and a significantly higher AF at the onset of oscillations with disgusting odor compared to pleasant or neutral odors (p < 0.001). The AF seems to reflect the functionality of the neuromuscular control, which can be impaired by disgusting olfactory inputs. An undisturbed functioning neuromuscular system appears to be characterized by a proper length-tension control and by an earlier onset of mutual oscillations during an external force increase under isometric conditions.