Effects of inertia on conformation and dynamics of active filaments

Many macroscopic active systems such as snakes, birds and fishes have flexible shapes and inertial effects on their motion, in contrast to their microscopic counterparts, cannot be ignored. Nonetheless, the consequences of interplay between inertia and flexibility on their shapes and dynamics remain unexplored. Here, we examine inertial effects on the most studied active flexible system, {\it i.e.} linear active filaments pertinent to worms, snakes and filamentous robots. Performing Langevin dynamics simulations of active polymers with underdamped and overdamped dynamics for a wide range of contour lengths and activities, we uncover striking inertial effects on their conformation and dynamics. Inertial collisions increase the persistence length of active polymers and remarkably alter their scaling behavior. In stark contrast to passive polymers, inertia leaves its fingerprint at long times by an enhanced diffusion of the center of mass. We rationalize inertia-induced enhanced dynamics by analytical calculations of center of mass velocity correlations, revealing significant contributions from active force fluctuations convoluted by inertial relaxation.Comment: 5 pages, 4 figure

Active motion of tangentially driven polymers in periodic array of obstacles

One key question about transport of active polymers within crowded environments is how spatial order of obstacles influences their conformation and dynamics when compared to disordered media. To this end, we computationally investigate the active transport of tangentially driven polymers with varying degrees of flexibility and activity in two-dimensional square lattices of obstacles. Tight periodic confinement induces notable conformational changes and distinct modes of transport for flexible and stiff active filaments. It leads to caging of low activity flexible polymers inside the inter-obstacle pores while promoting more elongated conformations and enhanced diffusion for stiff polymers at low to moderate activity levels. The migration of flexible active polymers occurs via hopping events, where they unfold to move from one cage to another, similar to their transport in disordered media. However, in ordered media, polymers are more compact and their long-time dynamics is significantly slower. In contrast, stiff chains travel mainly in straight paths within periodic inter-obstacle channels while occasionally changing their direction of motion. This mode of transport is unique to periodic environment and leads to more extended conformation and substantially enhanced long-time dynamics of stiff filaments with low to moderate activity levels compared to disordered media. At high active forces, polymers overcome confinement effects and move through inter-obstacle pores just as swiftly as in open spaces, regardless of the spatial arrangement of obstacles. We explain the center of mass dynamics of semiflexible polymers in terms of active force and obstacle packing fraction by developing an approximate analytical theory.</p

Active motion of tangentially driven polymers in periodic array of obstacles

One key question about transport of active polymers within crowded environments is how spatial order of obstacles influences their conformation and dynamics when compared to disordered media. To this end, we computationally investigate the active transport of tangentially driven polymers with varying degrees of flexibility and activity in two-dimensional square lattices of obstacles. Tight periodic confinement induces notable conformational changes and distinct modes of transport for flexible and stiff active filaments. It leads to caging of low activity flexible polymers inside the inter-obstacle pores while promoting more elongated conformations and enhanced diffusion for stiff polymers at low to moderate activity levels. The migration of flexible active polymers occurs via hopping events, where they unfold to move from one cage to another, similar to their transport in disordered media. However, in ordered media, polymers are more compact and their long-time dynamics is significantly slower. In contrast, stiff chains travel mainly in straight paths within periodic inter-obstacle channels while occasionally changing their direction of motion. This mode of transport is unique to periodic environment and leads to more extended conformation and substantially enhanced long-time dynamics of stiff filaments with low to moderate activity levels compared to disordered media. At high active forces, polymers overcome confinement effects and move through inter-obstacle pores just as swiftly as in open spaces, regardless of the spatial arrangement of obstacles. We explain the center of mass dynamics of semiflexible polymers in terms of active force and obstacle packing fraction by developing an approximate analytical theory

Photogrammetric Facial Analysis of Rhinoplasty Applicants in Shiraz

Background: Nose shape plays an important role in individuals’ facial appearance and its morphology depends on ethnicity, gender, and environmental conditions. Identifying nasal problems and measuring landmarks can lead to making a perfect surgery plan through preoperative image analysis. Methods: In this study, a photogrammetric analysis was performed on 120 female rhinoplasty applicants, aged 18-30 in Shiraz, Iran. Recorded parameters are nasal height and width, nasolabial and nasofrontal angle. Nasal indices were calculated according to heights and widths of noses. Also, facial asymmetry and nose hump checked for every patient. Results: Measurements showed that the average nasal index was 67.15 ± 4.72. Thus, the nose of rhinoplasty applicants was the leptorrhine type. Furthermore, the average nasofrontal and nasolabial angles were 145.22° ± 9.93°and 94.47° ± 14.25°. Among all applicants, 35 percent have an asymmetric nose and 31 percent have a nose hump. Conclusion:&nbsp; An accurate facial analysis of rhinoplasty applicants was performed in this study, and the resultant facial profiles can be used in nose surgery planning and in further ethnic research

Aeroelastic stability analysis of aircraft wings with initial curvature

In this study, the aeroelastic instability of a wing with an initial out-of-plane curvature is determined. The structural dynamics of the wing is modelled by using the geometrically exact beam equations, and the aerodynamic loads are determined using an incompressible unsteady aerodynamic model. The wing is considered to have initial out-of-plane curvature, and the effect of the curvature on the flutter velocity and flutter frequency of the wing is determined. Two curved wing cases are considered here. In the first case, the length of the wing is assumed to be constant and therefore, as the wing is curved, the projected area of the wing decreases. In the second case, the wing is assumed to have a constant projected area and therefore different curvature angles result from different wing lengths. When the wing is designed to have an initial out-of-plane curvature, the wing dynamics change, and therefore the aeroelastic stability of the curved wing is also affected. It is shown that as the initial curvature of the wing increases, initially the flutter velocity decreases but then increases, and finally a sudden jump occurs in the flutter velocity due to the change of the coupled modes contributing to flutter. Moreover, the flutter frequency also first decreases as the curvature of the wing increases, and then there is a sudden jump in the frequency, and from this point again the frequency decreases. Finally, results highlighting the importance of the initial curvature and the length of the curved segment on the stability velocity and frequency of the curved wing are presented

Aeroelastic Stability Analysis of Electric Aircraft Wings with Distributed Electric Propulsors

In this paper, the effect of distributed electric propulsion on the aeroelastic stability of an electric aircraft wing was investigated. All the electric propulsors, which are of different properties, are attached to the wing of the aircraft in different positions. The wing structural dynamics was modelled by using geometrically exact beam equations, while the aerodynamic loads were simulated by using an unsteady aerodynamic theory. The electric propulsors were modelled by using a concentrated mass attached to the wing, and the motor’s thrust and angular momentum were taken into account. The thrust of each propulsor was modelled as a follower force acting exactly at the centre of gravity of the propulsor. The nonlinear aeroelastic governing equations were discretised using a time–space scheme, and the obtained results were verified against available results and very good agreement was observed. Two case studies were considered throughout the paper, resembling two flight conditions of the electric aircraft. The numerical results show that the tip propulsor thrust, mass, and angular momentum had the most impact on the aeroelastic stability of the wing. In addition, it was observed that the high-lift motors had a minimal effect on the aeroelastic stability of the wing

Fuzzy uncertainty analysis in the flutter boundary of an aircraft wing subjected to a thrust force

In this study, flutter uncertainty analysis of an aircraft wing subjected to a thrust force is investigated using fuzzy method. The linear wing model contains bending and torsional flexibility and the engine is considered as a rigid external mass with thrust force. Peters’ unsteady thin airfoil theory is used to model the aerodynamic loading. The aeroelastic governing equations are derived based on Hamilton’s principle and converted to a set of ordinary differential equations using Galerkin method. In the flutter analysis, it is assumed that the wing static deflections do not have influence on the results. The wing bending and torsional rigidity, aerodynamic lift curve slope and air density are considered as uncertain parameters and modelled as triangle and trapezium membership functions. The eigenvalue problem with fuzzy input parameters is solved using fuzzy Taylor expansion method and a sensitivity analysis is performed. Also, the upper and lower bounds of flutter region at different α-cuts are extracted. Results show that this method is a low-cost method with reasonable accuracy to estimate the flutter speed and frequency in the presence of uncertainties

The muscle metabolome differs between healthy and frail older adults

Populations around the world are aging rapidly. Age-related loss of physiological functions negatively affects quality of life. A major contributor to the frailty syndrome of aging is loss of skeletal muscle. In this study we assessed the skeletal muscle biopsy metabolome of healthy young, healthy older and frail older subjects to determine the effect of age and frailty on the metabolic signature of skeletal muscle tissue. In addition, the effects of prolonged whole-body resistance-type exercise training on the muscle metabolome of older subjects were examined. The baseline metabolome was measured in muscle biopsies collected from 30 young, 66 healthy older subjects and 43 frail older subjects. Follow-up samples from frail older (24 samples) and healthy older subjects (38 samples) were collected after 6 months of prolonged resistance-type exercise training. Young subjects were included as a reference If thisgroup. Primary differences in skeletal muscle metabolite levels between young and healthy older subjects were related to mitochondrial function, muscle fiber type, and tissue turnover. Similar differences were observed when comparing frail older subjects with healthy older subjects at baseline. Prolonged resistance-type exercise training resulted in an adaptive response of amino acid metabolism, especially reflected in branched chain amino acids and genes related to tissue remodeling. The effect of exercise training on branched-chain amino acid-derived acylcarnitines in older subjects points to a downward shift in branched-chain amino acid catabolism upon training. We observed only modest correlations between muscle and plasma metabolite levels, which pleads against the use of plasma metabolites as a direct read-out of muscle metabolism and stresses the need for direct assessment of metabolites in muscle tissue biopsies

The combination of exercise training and Zataria multiflora supplementation increase serum irisin levels in postmenopausal women

Background:We examined the effect of antioxidant supplementation and exercise on irisin within postmenopausal women.Methods:Forty-eight participants (age: 55.7 ± 4.9 years; weight: 68.0 ± 6.3 kg; BMI 27.0 ± 2.7; mean ± SD) were randomized into four groups for the eight week intervention: control group (CG; n = 12), resistance training group (RTG; n = 12), supplementation with Zataria multiflora group (ZG; n = 12), or supplementation with Z. multiflora and resistance training group (ZRTG; n = 12). RTG and ZRTG performed circuit resistance training, and both ZG and ZRTG consumed 500 mg of Z. multifloraevery day during the intervention. Blood samples were taken 48 hours before and after the intervention.Results:There was a significant difference in irisin at post-training, with greater levels in ZRTG compared to CG. A significant increase was noted for irisin at post-training compared to pre-training for ZG, RTG, and ZRTG. Moreover, we identified a significant decrease in malondialdehyde in the RTG and ZRTG groups and increase in glutathione in the ZG, RTG, and ZRTG groups when compared to CG.Conclusion:These findings showed that exercise, Z. multiflora supplementation or their combination led to an increase in irisin