Magnetoresistance of metallic perovskite oxide LaNiO3−δ_{3-\delta}

We report a study of the magnetoresistance (MR) of the metallic perovskite oxide LaNiO$_{3-\delta}$ as a function of the oxygen stoichiometry $\delta$ ($\delta \leq$ 0.14), magnetic field (H $\leq 6T$) and temperature (1.5K $\leq$ T $\leq$ 25K). We find a strong dependence of the nature of MR on the oxygen stoichiometry. The MR at low temperatures change from positive to negative as the sample becomes more oxygen deficient (i.e, $\delta$ increases). Some of the samples which are more resistive, show a resistivity minima at $T_{min}$ $\approx$ 20K. We find that in these samples the MR is positive at T > $T_{min}$ and negative for T < $T_{min}$. We conclude that in the absence of strong magnetic interaction, the negative MR in these oxides can arise from weak localisation effects.Comment: 10 pages in REVTeX format, 4 eps fig

Computer simulation study of the subquadratic quantum number dependence of vibrational overtone dephasing: comparison with the mode-coupling theory predictions

Experimental studies have demonstrated that the vibrational dephasing of overtones do not always follow the quadratic quantum number (n) dependence predicted by the Kubo-Oxtoby theory of vibrational line shapes. While the reason for this failure of the theory is not quite clear yet, a recent theory suggested that the pronounced Gaussian time dependence of the frequency-modulation time-correlation function (tcf) could be a possible reason [Gayathri et al., J. Chem. Phys., 107, 10381 (1997)]. The theoretical study was based on a mode coupling theory calculation of the force-force time-correlation function that is required in the calculation of the frequency-modulation tcf. In order to test this and other predictions of the above study, detailed computer simulations of two neat liquids have been carried out. The systems studied are N-N stretch in liquid N2 and the C-I stretch in CH3I. It is found that although the frequency-modulation time-correlation function is largely Gaussian in both the cases, the overtone dephasing remains largely quadratic in n for N2. For methyl iodide, on the other hand, a pronounced sub-quadratic n dependence has been observed. Both the theory and the computer simulations suggest that this nonquadratic dependence can be expected when not only the decay of the frequency time-correlation function is Gaussian but the time scale of decay of the frequency-modulation tcf is comparable to that of the normal coordinate. The latter can happen when the following conditions are satisfied. First, the frequency of the normal mode should not be too large. Second, the mean-square fluctuation of the frequency-modulation and the anharmonicity coefficient of vibration should be large. It is found that both for N2 and CH3I, the resonant energy transfer between different molecules is significant. The effect of rotational-vibrational coupling, on the other hand, is found to be negligible for the systems studied

Thematic and Stylistic Analysis of Maya Angelou Poems: A Review of Literature

Poetry is a form of creative art, through which many writers express their emotions, feelings, and also their bitter experiences to the world. Poetry, along with autobiography helped in the revelation of self, especially among African-Americans. Black women writers, in particular, have experienced many trials and tribulations while struggling for identity and freedom in the land of America. As women were considered inferior since the early period, their writings reflect deeply on their life stories and create a positive self-identity. Qualitative descriptive method is commonly used in the reviewed articles. This article examines the existing research on Angelou’s poems with the explored areas such as racism, gender issues, figurative analysis, feminism, stylistics, etc., and identifies the characteristics of self-portrait in them

Probing into the Psyche of Subalterns in August Wilson’s Joe Turner’s Come and Gone.

The subjugation and suppression that blacks meet in America causes ineradicable wounds in the psyche of the blacks which they try to remove from their later generations. The present paper probes into the psyche of the African Americans in August Wilson‟s Joe Turner‟s Come and Gone in the Pittsburgh Century Cycle and delves how Wilson employs the „blood memory‟ as a primary power to overcome the psychic exile suffered by his characters. By navigating back to the origin of the African American trauma, the play instructs blacks to see through their problems, to reconnect and rebuild themselves with their own historical ancestor slave trade. To solve their imminent problems blacks must seek a positive self-knowledge that transforms their misery into love, power and hope. Wilson persistently insists that African Americans have to upright their impending life only through the diasporic reminiscence. The remembrance makes an individual to transform his ordeal and captivates how to edify others‟ life with the history of the slaves‟ voyage

Prospective study on sonographic measurement of umbilical cord thickness, foetal fat layer, interventricular septal thickness as predictors of macrosomia in fetus of women with gestational diabetes mellitus

Background: The objectives of the study were to evaluate the Prediction of foetal macrosomia based on sonographic measurements of foetal fat layer, Interventricular septal thickness and umbilical cord thickness in Gestational Diabetes Mellitus at term.Methods: After assessment of inclusion and exclusion criteria 100 antenatal women of gestational age more than 37 weeks selected for study in the Department of Obstetrics and Gynaecology of Vinayaka Mission’s Kirupananda variyar medical college and hospital, Salem. Participants underwent a third trimester scan and three extra measurements i.e. Umbilical cord thickness, Interventricular septal thickness and foetal fat layer are measured in addition to the normal examination.Results: In present study umbilical cord thickness had good sensitivity and negative predictive value. Hence, if umbilical cord thickness is less than 90th centile the chance of macrosomia is less, the cut off of foetal fat layer ≥5 mm as predictor of macrosomia had sensitivity of 84.2% and specificity of 86.4% and cut off of Interventricular septal thickness ≥3.9mm as a predictor of macrosomia had sensitivity of 84.2%, specificity of 64.2%, negative predictive value of 95.9%. Thus, interventricular septal thickness and foetal fat layer is a reliable predictor of macrosomia.Conclusions: From this study authors concluded that Umbilical cord thickness, foetal fat layer and Interventricular septal thickness are good predictors of foetal macrosomia. In the assessment of risk of macrosomia in addition to the ultrasonographic measurements the clinical risk factors must be considered