Phase-Plane Analyses of Parametrically and Self Excited Mechanical Systems

In order to investigate the behaviors of parametrically and self-excited mechanical systems, graphically analytic methods in the phase plane are proposed. Unstable phenomena like parametric and self-excited vibrations happen to appear in rotating machinery with a crack, a rub, the looseness and so on. Such unfavorable vibrations should be detected and predicted as early as possible. In this paper, their characteristics are investigated and a fundamental view for describing and analyzing nonlinear models is presented

Asymmetry of Force Fluctuation During Low Intensity Isometric Contraction In Leg Muscle

Int J Exerc Sci 3(2) : 68-77, 2010. The purpose of this study was to investigate the asymmetry of force fluctuation in the leg muscles during isometric knee extension and flexion. Twenty healthy males (21±2 years) performed the maximal voluntary isometric contraction (MVC) in knee extensor and flexor. On the basis of MVC measurement, the subjects performed sustained isometric knee extension and flexion for 15s at levels corresponding to 10%, 20% and 30% MVC. The main findings of this study were: (1) a greater force fluctuation was found in the stronger MVC limb than in the weaker MVC limb at 30% MVC; (2) no difference was found in the force fluctuation between the stronger and weaker MVC limbs at 10% and 20% MVC; and (3) significant positive correlations were found between the target force values and the force fluctuation at each contraction intensity. These results suggest that: (1) asymmetry of force fluctuation increases with load, (2) asymmetry of the force fluctuation is observed at more than 30% MVC intensity; and (3) if the contraction intensity is same relatively loads (% MVC), force fluctuation is increase with absolute load (target force value). Force fluctuation influence the functional ability of an individual in controlling finger or limb movements in daily life. Further, asymmetry of force fluctuation might influence for more than 30% MVC of daily activities

Vibration Analysis of Ventilating Fan

The hydromatic machines， which are represented by blowers， ventilating fans， pumps etc.，usually consist of moters and blades. They sometimes ‘cause large amplitude of vibration， and then yield much dynamic stress on the roots of blades excited rotating unbalance forces， generated by sticked dirts on the blades， for example. Most undesirable case of operation for these machines is to the resonance phenomena between the natural frequencies of system and exciting forces. Therefore it is necessary to provide for the calculated natural frequencies of them， so we tried to calculate them assumed the system consist of a mass and springs of supporting structure using the flexibility matrix method. The results obtained from the calculation agree well with the measurements and then guidelines for design of these machines are required

FXYD3 functionally demarcates an ancestral breast cancer stem cell subpopulation with features of drug-tolerant persisters

乳がんの再発を起こす原因細胞を解明. 京都大学プレスリリース. 2023-11-16.The heterogeneity of cancer stem cells (CSCs) within tumors presents a challenge in therapeutic targeting. To decipher the cellular plasticity that fuels phenotypic heterogeneity, we undertook single-cell transcriptomics analysis in triple-negative breast cancer (TNBC) to identify subpopulations in CSCs. We found a subpopulation of CSCs with ancestral features that is marked by FXYD domain–containing ion transport regulator 3 (FXYD3), a component of the Na⁺/K⁺ pump. Accordingly, FXYD3⁺ CSCs evolve and proliferate, while displaying traits of alveolar progenitors that are normally induced during pregnancy. Clinically, FXYD3⁺ CSCs were persistent during neoadjuvant chemotherapy, hence linking them to drug-tolerant persisters (DTPs) and identifying them as crucial therapeutic targets. Importantly, FXYD3⁺ CSCs were sensitive to senolytic Na⁺/K⁺ pump inhibitors, such as cardiac glycosides. Together, our data indicate that FXYD3⁺ CSCs with ancestral features are drivers of plasticity and chemoresistance in TNBC. Targeting the Na⁺/K⁺ pump could be an effective strategy to eliminate CSCs with ancestral and DTP features that could improve TNBC prognosis