Dynamics and symmetries of flow reversals in turbulent convection

Based on direct numerical simulations and symmetry arguments, we show that the large-scale Fourier modes are useful tools to describe the flow structures and dynamics of flow reversals in Rayleigh-B\'enard convection (RBC). We observe that during the reversals, the amplitude of one of the large-scale modes vanishes, while another mode rises sharply, very similar to the "cessation-led" reversals observed earlier in experiments and numerical simulations. We find anomalous fluctuations in the Nusselt number during the reversals. Using the structures of the RBC equations in the Fourier space, we deduce two symmetry transformations that leave the equations invariant. These symmetry transformations help us in identifying the reversing and non-reversing Fourier modes.Comment: 4 pages, 3 figure

Flow reversals in turbulent convection via vortex reconnections

We employ detailed numerical simulations to probe the mechanism of flow reversals in two-dimensional turbulent convection. We show that the reversals occur via vortex reconnection of two attracting corner rolls having same sign of vorticity, thus leading to major restructuring of the flow. Large fluctuations in heat transport are observed during the reversal due to this flow reconfiguration. The flow configurations during the reversals have been analyzed quantitatively using large-scale modes. Using these tools, we also show why flow reversals occur for a restricted range of Rayleigh and Prandt numbers

A Simple Approach for Black Out Problem

Antennas surrounding by the plasma medium does not radiate for all the frequencies but only for those which are greater than the plasma frequency. Here we have proposed a cylindrical (axial magnetized) antenna system which radiates for all frequencies irrespective of plasma frequency and this is the solution for the black-out situation which occurs for certain frequencies

Role of Bulk flow in Turbulent Convection

In this paper we present scaling of large-scale quantities like Pecl\'{e}t and Nusselt numbers, and the dissipation rates of kinetic energy and entropy. Our arguments are based on the scaling of bulk quantities and earlier experimental and simulation results. We also present the inertial-range properties of spectra and fluxes of kinetic energy and entropy.Comment: 15 pages, to Appear in the proceedings of "Senfest, International Conference on Complex Processes in Plasmas and Nonlinear Dynamical Systems

A comparative study of depression among infertile and fertile women

Background: Infertility has been a major medical and social preoccupation since the dawn of human existence and women have always been the symbol of fertility. Infertility is a stressful life event and depressive symptoms are normal responses to the life crisis of the infertile women. Aim and objective of the study was to determine the severity of depression in infertile females as compared to control group and to correlate the duration of infertility to depression in infertile females.Methods: The Present study was carried out on 70 patients in both groups. After randomization, assessment of Sociodemographic details was done with the help of semi-structured performa and severity of depression by beck depression rating scale. The proposed study was conducted in phased manner observing ethics of voluntary participation and informed consent of the participants were taken.Results: Both the groups were comparable with respect to age, socioeconomic status, occupation, education, religion, family type and area. No significant differences found between both groups with respect to the sociodemographic profile (p-value >0.05). The mean age of infertile women was 28.72 year and fertile women 27.45 years. We found that maximum female was from a middle class in both groups, 48 (68.57%) in infertile and 50 (71.42%) in the fertile group.Conclusions: Depression was more in infertile women. Depression severity was positively correlated with age of women and duration of infertility. Low socioeconomic status, low educated and rural background was a risk factor for severity of depression for infertile women.

Uterine perforation with bowel prolapsing through vagina following an unsafe abortion

An unwanted pregnancy may lead to induced abortion that means willful termination of pregnancy before the period of viability. Most of the times when termination of pregnancy is done by skilled person in fully aseptic environment, complications are low. But severe complication including uterine perforation, bowel injury, sepsis and sometimes death is common when the procedure is carried out by unskilled personnel in unhealthy condition. This case representing the neglected scenario of our maternal health facilities in rural areas where many untrained care providers are still performing illegal and unsafe abortion without knowledge of its grave consequences