A computational study has been carried out to examine the effects of ribs and cavities on flow and heat transfer in a convergent-divergent shaped microchannel heat sink with constant heat flux for Reynolds number (Re) ranging from 120 to 900. Three-dimensional governing equations were discretized using the finite-volume method. The computational domain included solid silicon and fluid regions. A significant amount of work has been reported in the literature on the individual effects of channel shape and flow disruption using obstacles on thermal performance of microchannels. In the present study convergent-divergent (CD) shaped microchannel with and without ribs and cavities (RC) are considered and their friction coefficient, thermal resistance and maximum substrate temperature are investigated in detail. The present results show that the usage of CD shape with ribs and cavities can reduce the overall thermal resistance up to 40% and make the bottom surface temperature quite uniform. This heat transfer enhancement is mainly due to interruption and redevelopment of boundary-layers along with recirculation zone. The results also show that increasing Re leads to an enhanced heat transfer in terms of increased averaged Nusselt number from 15% to 46%. The combined effect of CD shape with RC is quite effective in heat transfer augmentation but it gradually loses its effectiveness at large values of Re due to a high pressure drop penalty.

BACKGROUND AND AIM: Left ventricular dilatation is a well recognized precursor of ventricular dysfunction and congestive heart failure after myocardial infarction. Present study is to evaluate the Left ventricular geometry and the determinants of L.V. geometry by M-mode Echocardiography in subjects after acute MI. METHOD: A hospital based prospective study was conducted at tertiary care center in Uttar Pradesh, India with a total of 30 patients including 17 Males and 13 Females having acute MI along  with thorough  General Examination / history taking and Demographic profile assessment. Detailed L.V. geometrical parameters were assessed by Echocardiography  at lateral  and septal sides of  L.V. at the level of mitral annulus on 1st day of admission. Data was analyzed for males/females and calculations were done by using Microsoft Excel 2010 software. RESULTS: The geometrical parameters were compared and analysed. P value was calculated. P value<0.0001 gave highly significant results and <0.05 gave significant results. LVIDd(<0.05), LVIDs(<0.05), PWTd(<0.05), LVM(<0.05), LVMI(BSA)(<0.05), LVMI(Ht2.7)(<0.05), LVMI(g/m)(<0.05) were significant respectively. CONCLUSION: From the study, it can be concluded that the overall L.V. geometry was affected among Acute Myocardial Infarction patients.

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Introduction: Left ventricular hypertrophy (LVH) is an important predictor of mortality and morbidity in hypertension, leading to hypertensive heart disease (HHD). Left ventricular mass (LVM), therefore, chiefly determines the geometrical reorientation of LV in hypertensives and these geometrical patterns are useful determinant of severity and prognosis of congestive heart failure (CHF). Studies on the geometrical assessment of LV in hypertensive patients involving large number of patients are limited in India. 2-D Echocardiography, is a non-invasive, cost effective, and a gold standard technique in the early detection of LV hypertrophy in hypertensive patients. Aims and Objectives: To determines the structural and functional integrity of LV in accordance with the variability of the LV geometry and function in recently detected hypertensive patients by 2D-Echocardiography and Colour Doppler. Material and Methods: 2D-Echocardiography and colour Doppler was done in 1000 randomly selected patients in OPD with accidently detected hypertension. LV geometrical patterns were determined by using Echocardiographic parameters chiefly left ventricular mass (LVM), left ventricular mass index to the power 2.7 of ht. (LVMI) and relative wall thickness (RWT) were recorded according to American society of Echocardiography convention (ACE). Results and Observations: Four patterns of LV geometry were noted i.e. concentric hypertrophy (CH) (22.9%), eccentric hypertrophy (EH) (9.7%), and concentric remodeling (CR) (50%) and normal geometry (NG) (17.4%). In this study, we observed that patients with concentric hypertrophy were significantly (<0.0001) older than the normal geometry and had significantly elevated pressures SBP (.0130), DBP (0.0363), MAP (.0038) and PP (0.0217) higher than in normal geometry. Diastolic dysfunction was detected in hypertensive patients with concentric hypertrophy and eccentric hypertrophy, abnormal LV patterns observed in our study. LV systolic function was significantly lower in patients with eccentric hypertrophy and some degree of diastolic dysfunction was present in abnormal geometry. Conclusion:The study determines that if there are regular screenings of the high blood pressure, then early steps can be taken to detect the establishment of LV hypertrophy.