123 research outputs found

    Multiresolution Wavelet Analysis of the Dynamics of a Cracked Rotor

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    We examine the dynamics of a healthy rotor and a rotor with a transverse crack, which opens and closes due to its self weight. Using discrete wavelet transform, we perform a multiresolution analysis of the measured vibration signal from each of these rotors. In particular, the measured vibration signal is decomposed into eight frequency bands, and the rms amplitude values of the healthy and cracked rotors are compared in the three lowest-frequency bands. The results indicate that the rms vibration amplitudes for the cracked rotor are larger than those of the healthy rotor in each of these three frequency bands. In the case of externally applied harmonic force excitation to the rotor, the rms values of the vibration amplitude of the cracked rotor are also found to be larger than those of a healthy rotor in the three lowest-frequency bands. Furthermore, the difference in the rms values between the healthy and cracked rotors in each of the three lowest-frequency bands is more pronounced in the presence of external excitation than that with no excitation. The obtained results suggest that the present multiresolution approach can be used effectively to detect the presence of a crack in a rotor

    On the occurrence of feulgen positive nucleoli in adrenocortical cells of the pigeon

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    Effects of Unpredictable Variable Prenatal Stress (UVPS) on Bdnf DNA Methylation and Telomere Length in the Adult Rat Brain

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    In utero exposure to stress can shape neurobiological and behavioral outcomes in offspring, producing vulnerability to psychopathology later in life. Animal models of prenatal stress likewise have demonstrated long-term alterations in brain function and behavioral deficits in offspring. For example, using a rodent model of unpredictable variable prenatal stress (UVPS), in which dams are exposed to unpredictable, variable stress across pregnancy, we have found increased body weight and anxiety-like behavior in adult male, but not female, offspring. DNA methylation (addition of methyl groups to cytosines which normally represses gene transcription) and changes in telomere length (TTAGGG repeats on the ends of chromosomes) are two molecular modifications that result from stress and could be responsible for the long-term effects of UVPS. Here, we measured methylation of brain-derived neurotrophic factor (bdnf), a gene important in development and plasticity, and telomere length in the brains of adult offspring from the UVPS model. Results indicate that prenatally stressed adult males have greater methylation in the medial prefrontal cortex (mPFC) compared to non-stressed controls, while females have greater methylation in the ventral hippocampus compared to controls. Further, prenatally stressed males had shorter telomeres than controls in the mPFC. These findings demonstrate the ability of UVPS to produce epigenetic alterations and changes in telomere length across behaviorally-relevant brain regions, which may have linkages to the phenotypic outcomes

    A Full-Potential-Linearized-Augmented-Plane-Wave Electronic Structure Study of delta-Plutonium and the (001) Surface

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    The electronic and geometric properties of bulk fcc delta-plutonium and the quantum size effects in the surface energies and the work functions of the (001) ultra thin films (UTF) up to 7 layers have been investigated with periodic density functional theory calculations within the full-potential linearized augmented-plane wave (FP-LAPW) approach as implemented in the WIEN2k package. Our calculated equilibrium atomic volume of 178.3 a.u.^3 and bulk modulus of 24.9 GPa at the fully relativistic level of theory, i.e. spin-polarization and spin-orbit coupling included, are in good agreement with the experimental values of 168.2 a.u.^3 and 25 GPa (593 K), respectively. The calculated equilibrium lattice constants at different levels of approximation are used in the surface properties calculations for the thin films. The surface energy is found to be rapidly converged with the semi-infinite surface energy predicted to be 0.692eV at the fully-relativistic level.Comment: 27 pages,8 figure

    The Role of Ultrasonographic Biomicroscopy in the management of a patient with presumed Dematiaceous Mycotic Keratitis - ISPUB

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    We report the use of Ultrasonographic Biomicroscopy in the management of a patient with presumed dematiaceous mycotic keratitis. AK Tan, PS Premsenthil, A. Aziz, T. Asok, G. Inta

    Posterior scleritis mimicking indirect carotid-cavernous fistula

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    Tan Aik Kah, Mallika Premsenthil, Mohamad Aziz Salowi, Asokumaran Thanaraj & Intan ak Gudo

    Ethambutol ocular toxicity in a patient with pulmonary tuberculosis a case report

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    Purpose. To highlight the importance of using the Farnsworth Panel D-15 Hue test in colour vision testing in patients on ethambutol treatment. Case Report. A 70 year-old lady received ethambutol as part of her anti-tuberculous regime. She developed blue-yellow colour defect detectable with the Farnsworth Panel D-15 Hue test, but not with the Isihara Pseudoisochromatic Plates. Ethambutol was immediately discontinued from her anti-tuberculous regime. Two months later, her colour vision returned to normal. Conclusion. This case report illustrates the importance of regular monitoring of patients receiving ethambutol for blue-yellow colour defect using the Farnsworth Panel D-15 Hue Test
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