Determination Of Critical Speed Research Articles

Metabolic correlates to critical speed in murine models of sickle cell disease.

Introduction: Exercise intolerance is a common clinical manifestation in patients with sickle cell disease (SCD), though the mechanisms are incompletely understood. Methods: Here we leverage a murine mouse model of sickle cell disease, the Berkeley mouse, to characterize response to exercise via determination of critical speed (CS), a functional measurement of mouse running speed upon exerting to exhaustion. Results: Upon observing a wide distribution in critical speed phenotypes, we systematically determined metabolic aberrations in plasma and organs-including heart, kidney, liver, lung, and spleen-from mice ranked based on critical speed performances (top vs. bottom 25%). Results indicated clear signatures of systemic and organ-specific alterations in carboxylic acids, sphingosine 1-phosphate and acylcarnitine metabolism. Metabolites in these pathways showed significant correlations with critical speed across all matrices. Findings from murine models were thus further validated in 433 sickle cell disease patients (SS genotype). Metabolomics analyses of plasma from 281 subjects in this cohort (with HbA < 10% to decrease confounding effects of recent transfusion events) were used to identify metabolic correlates to sub-maximal exercise test performances, as measure by 6min walking test in this clinical cohort. Results confirmed strong correlation between test performances and dysregulated levels of circulating carboxylic acids (especially succinate) and sphingosine 1-phosphate. Discussion: We identified novel circulating metabolic markers of exercise intolerance in mouse models of sickle cell disease and sickle cell patients.

Prilog određivanju kritične i dopuštene brzine kretanja brodova u plovnim kanalima

Prilog određivanju kritične i dopuštene brzine kretanja brodova u plovnim kanalima

Determination of Critical Speed in Ice Breaking by Air Cushion Vehicle

On the basis of the differential equation governing small flexure of thin elastic vibrating plate, the formula for calculating the phase velocity and group velocity of ice sheet wave propagation under the air cushion load is induced. The minimum of the phase velocity is the critical speed about ice breaking by air cushion vehicle (ACV). If ACV moves at the critical speed, the energy causing the deformation of ice sheet is concentrated constantly, thus the amplitude of the wave is enlarged enough to break the ice by resonance.

Determination of Critical Speeds of the Rotor of the Electric Pump

Some questions connected to definition of critical speeds of a rotor of the electrical pump are discussed in the article. The examined system is complex elastic one with the distributed and concentrated masses. The considered rotor is based on two supports with anisotropic hardness. In such case the pump has 3D-motion. A method of initial parameters, in our opinion, is used by the most convenient at analysis of this elastic system.

Generalized Polynomial Expansion Method for the Dynamic Analysis of Rotor-Bearing Systems

The determination of critical speeds and modes and the unbalance response of rotor-bearing systems is investigated with the application of a technique called the generalized polynomial expansion method (GPEM). This method can be applied to both linear and nonlinear rotor systems; however, only linear systems are addressed in this paper. Three examples including single spool and dual rotor systems are used to demonstrate the efficiency and the accuracy of this method. The results indicate a very good agreement between the present method and the finite element method (FEM). In addition, computing time will be saved using this method in comparison with the finite element method.