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Nonlinear bending vibration of a prestressed thick plate
Francisco J. Nieves,Ana Bayón,Francisco Gascón,Rafael Medina,Félix Salazar 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.4
In this paper, the flexural vibration frequency in the antisymmetric mode of a thick plate as a function of the amplitude of the vibration and the axial force applied is investigated. With this aim, the theory of geometrically nonlinear deformation of second order and an optimized three-dimensional Ritz method are used. The plate is homogeneous, elastically linear, free from any constraints, and subjected to axial forces uniformly distributed on two of its opposite sides. Several approaches are discussed. First, the problem based on finite stress and infinitesimal strains is solved. Second, the deformation energy is assumed as the energy in the initial state plus the vibration energy of small or large amplitude. Third, without assumptions about the size of the deformation and of the vibration amplitude, the theory of nonlinear deformation is employed. Finally, numerical calculations for free vibration are compared with experimental results, including their systematic uncertainties.
Accumulation of High Levels of ABA Regulates the Pleiotropic Response of the nhr1 Arabidopsis Mutant
Francisco Quiroz-Figueroa,Adrián Rodríguez-Acosta,Amed Salazar-Blas,Elizabeta Hernández-Domínguez,Maria Eugenia Campos,Nobutaka Kitahata,Tadao Asami,Rosa M. Galaz-Avalos,Gladys I. Cassab 한국식물학회 2010 Journal of Plant Biology Vol.53 No.1
Plants have evolved a variety of mechanisms for responding to environmental cues, which allows them to survive in the presence of limited resources or environmental stresses. One of the most significant growth adaptations plants have attained is tropism, a growth response that involves bending of plant organs toward or away from a stimulus. Roots exhibit hydrotropism in response to moisture gradients, which is thought to be critical in acquiring water and establishing their stand in the soil. However, the mechanism underlying hydrotropism remains unsolved. Here, we report that the no hydrotropic response (nhr1) mutant of Arabidopsis, which is impaired in hydrotropism, is tolerant to drought. The no hydrotropic response phenotype of nhr1 was repressed by AbamineSG,an inhibitor of abscisic acid (ABA) biosynthesis, indicating that ABA negatively regulates hydrotropism. Furthermore,the content of ABA was higher in nhr1 compared to those of wild type (wt). However, the higher ABA levels in nhr1plants were not due to higher transcript levels of 9-cisepoxycarotenoid dioxygenase (NCED3), since these were diminished compared to those of wt. Our results indicated that the root hydrotropic response of the nhr1 mutant is modulated by ABA and that the higher ABA levels of the mutant might confer it drought resistance.
Nydia Ávila-Vanzzini,Juan Francisco Fritche-Salazar,Nelva Marina Vázquez-Castro,Pedro Rivera-Lara,Oscar Pérez-Méndez,Humberto Martínez-Herrera,Mario Gómez-Sánchez,Alberto Aranda-Frausto,Héctor Herrera 한국심초음파학회 2016 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.24 No.4
Background: Severe aortic stenosis (AS), leads to pathological left ventricular remodeling that may worsen with concomitantoverweight and obesity (OW/O). Methods: We aimed to prospectively analyze the impact of OW/O on ventricular remodeling in severe AS, by evaluating thepercentage of intraendomyocardial fibrosis (PIEF) and the percentage of infiltrating intraendocardial lipid vacuoles (PIELV) andits relationship to global longitudinal strain (GLS) in patients with OW/O. Results: 44 patients with severe AS were included, 13 non-obese (29%) and 31 OW/O (71%), all of them with left ventricularejection fraction ≥ 55%. GLS was evaluated with 2D speckle tracking. During valve replacement, an endocardial biopsy wasobtained, where PIEF and PIELV were analyzed. Patients with higher PIEF and PIELV had greater body mass index (p < 0.0001)and worse GLS (p < 0.0053). A GLS cut-off point < -14% had a sensitivity of 75%, and a specificity of 92.8% to detect importantPIEF (AUC: 0.928, 95% confidence interval: 0.798–1.00). On multivariate analysis, OW/O and PIELV were independentlyassociated to the PIEF, and OW/O and PIEF were independently associated to GLS. A high correlation between the amount ofPIELV and PIEF were found. Conclusion: Patients with severe AS and OW/O have greater PIEF and PIELV, suggesting more pathological remodeling. GLS is useful to detect subclinical myocardial injury and is potentially useful for endomyocardial fibrosis detection. The presenceof higher PIELF may be a trigger factor for the development of intraendomyocardial fibrosis.