Robustness of Multiple Imputation under Missing at Random (MAR) Mechanism: A Simulation Study

Missing data is an unavoidable issue in controlled clinical trials and public health research and practice. Presence of missing data and applying inappropriate methods of analysis generates biased estimates and reduces power of study. It is very important for investigators to use appropriate methods of analysis to deal with missing data in order to maintain internal (power of study) and external (generalization of sample results to larger population) validity of study. The focus of this dissertation is to compare different methods to deal with missing data in controlled clinical trials and public health research and practice. In addition, this dissertation also discusses that current approaches to deal with missing data might not produce valid inferences and may affect internal and external validity of results. Furthermore, emphasis is put on demonstrating how well multiple imputation works to deal with missing data under Missing at Random (MAR) mechanism with monotonic and non-monotonic missing data patterns for a range of percent missing under both normal and non-normal distributions. The results of this dissertation showed that multiple imputation is an efficient technique to obtain valid inferences compared to single imputation methods. In addition estimates obtained from multiple imputation also preserve the internal validity of study

Comparison of Amsel’s criteria and Nugent’s criteria for diagnosis of bacterial vaginosis in tertiary care centre

Background: Bacterial vaginosis is an imbalance in the ecology of the normal vaginal flora which is characterized by depletion of lactobacilli, and proliferation of anaerobic bacteria. It most often manifests clinically as a vaginal pH of > 4.5, presence of thin whitish homogenous vaginal discharge, detection of “clue” cells and presence of an amine odour after the addition of 10 percent potassium hydroxide. These anaerobic bacteria through specific products stimulate the decidual tissue causing an increase of cytokine level, release of phospholipase A2 and prostaglandins leading to preterm labor, premature rupture of membranes, chorioamnionitis and development of PID following abortion. To compare Amsel Criteria and Nugent Criteria for diagnosis of bacterial vaginosis.Methods: A cross sectional study involving 260 patients with preterm and term labour was conducted at a tertiary care hospital in North India. BV was determined to be present or absent on the basis of Amsel’s criteria and Nugent’s criteria. Pearson’s chi-square test was used to demonstrate the difference between both groups with respect to various categorical data.Results: Amsel’s criteria and Nugent’s criteria were reliable diagnostic methods. As compared to Nugent scoring system, Amsel’s criteria had sensitivity of 75%, specificity of 95%, positive predictive value of 90% and negative predictive value of 86%.Conclusions: Although the Amsel’s criteria is a convenient and inexpensive method of diagnosing bacterial vaginosis, it is not always reliable. Nugent’s criteria is considered as a gold standard for the diagnosis of bacterial vaginosis but it requires an experienced slide reader and considerable time and skill. If lab equipment is not available as in many developing countries, the diagnosis of BV can be simplified by using a combination of any two Amsel’s criteria like vaginal pH and whiff test which had highest sensitivity and specificity (90.19% and 97.78%) respectively as seen in present study

Role of a periodic varying deceleration parameter in Particle creation with higher dimensional FLRW Universe

The present search focus on the mechanism of gravitationally influenced particle creation (PC) in higher dimensional Friedmann-Lemaitre-Robertson-Walker(FLRW) cosmological models with a cosmological constant (CC). The solution of the corresponding field equations is obtained by assuming a periodically varying deceleration parameter (PVDP) i.e. $q= m \cos kt - 1$ [Shen and Zhao, Chin. Phys. Lett., 31 (2014) 010401] which gives a scale factor $a(t) = a_0 \left[\tan \left(\frac{kt}{2}\right)\right]^\frac{1}{m}$, where $a_0$ is the scale factor at the current epoch. Here $k$ displays the PVDP periodicity and can be regarded as a parameter of cosmic frequency, $m$ is an enhancement element that increases the PVDP peak. Here, we investigated the periodic variation behavior of few quantities such as the deceleration parameter $q$, the energy density $\rho$, PC rate $\psi$, the entropy $S$, the CC $\Lambda$, Newton's gravitational constant $G$ and discuss their physical significance. We have also explored the density parameter, proper distance, angular distance, luminosity distance, apparent magnitude, age of the universe, and the look-back time with redshift $z$ and have observed the role of particle formation in-universe evolution in early and late times. The periodic nature of various physical parameters is also discussed which are supporting the recent observations.Comment: 19 pages, 15 figure

Graves hyperthyroidism in pregnancy: a rare presentation

Hyperthyroidism in pregnancy is much less common occurring in 0.1-0.2% of women with Grave’s disease being the most common cause accounting for 90% of the cases. It is important to diagnose hyperthyroidism in pregnancy because fetal loss in untreated patients is high and may even be life threatening for the mother. We are presenting a case of 29 years old G3P2L1 who presented to our emergency with amenorrhea of 7 months and history of loose stools for the last 20 days. It was associated with generalized weakness. She also had history of palpitations, weight loss and sleep disturbances. She was a known case of hyperthyroidism for the past 1-2 years and was already taking anti-thyroid drugs. B/L exophthalmos was apparently present. Patient was severly anaemic with haemoglobin of 5.5gms/dl. Ultrasound showed fetal demise at 28weeks. Patient was given 3 units of blood transfusion and was induced with prostaglandins. She delivered a dead male baby weighing 1.2kgs. Her postpartum period was uneventful. Timely diagnosis of graves hyperthyroidism and its optimal treatment throughout pregnancy is vital in reducing maternal, fetal and neonatal complications.

A Comparative Study on Histogram Equalization and Cumulative Histogram Equalization

Image enhancement is a way to improve the appearance of image to human viewers or to image processing system performance. Image Enhancement techniques can be classified into two categories as spatial domain and frequency domain. There arenbsp five image enhancement algorithms in spatial domain using FPGA technology. These algorithms are: median filter, contrast stretching, histogram equalization, negative image transformation and power-law transformation. This review paper presents different methods of histogram equalization. Histogram equalization is a method to enhance an image very efficiently. Histogram equalization methods are Histogram expansion, Local area histogram equalization (LAHE), Cumulative histogram equalization, Par sectioning, odd sectioning

Prevalence of thinness among the adolescent girls (age group 13yrs-18yrs) of Garhkhal Village of Himachal Pradesh, India.

Malnutrition has now been redefined in terms of “under nutrition” and conceptualized in terms of thinness which is an important problem among children and adolescents in rural areas of developing countries like India. Therefore, present study was carried out to assess the prevalence of thinness among the adolescent girls (age group 13yrs-18yrs) of Garhkhal Village of Himachal Pradesh, India. The study design was cross-sectional. Height and weight were measured and Body Mass Index (BMI) was carried out. Identification of thinness was done according to the new International BMI-based classification cut offs as given by Cole et al., 2007. In general the mean BMI increased with increasing age. Overall age-combined prevalence was 79.5%. Present study indicated the poor health status of the adolescent girls of the selected area which indicates the high nutritional stress among them as evident from the thinness prevalent among them

Risk factors associated with development of senile cataract

Background: Cataract is the most common cause of reversible blindness worldwide, which has been associated with various causative risk factors. Hence, we aim to study the factors that might play a role in cataractogenesis. Material and methods: A total of 240 eyes of 240 subjects were included for the study, which consisted of 120 cases with age-related cataract and 120 age-matched controls, and in them various factors like blood pressure, body mass index (BMI), smoking, sun exposure, and serum cholesterol were studied. Results: A statistically significant difference between the two groups was found with respect to smoking profile (p = 0.007), sun exposure (p = 0.001), and serum cholesterol (p < 0.001). Subjects who were smokers, had a longer exposure to sun, and had higher serum cholesterol level were found to be positively associated with development of cataract. No significant association between BMI (p = 0.384) and blood pressure (p > 0.05) was observed. Conclusion: Higher cholesterol levels, increased sun exposure, and smoking habit play a role in the development of senile cataract, and these are modifiable risk factors. Hence, control of these might help in delaying formation and progression of cataract

Study of Future Wireless Technology: Li-Fi

Since the day earth exists, human is going develop day by day. New technologies are generated as human beings are developing. Now, internet is a compulsory part of our life. We are using Wi-Fi for internet access. But it has some limitations, so there is a new wireless technology i.e. Li-Fi (Light Fidelity), which overcomes some of the shortcomings of Wi-Fi. This paper consists a study of Li-Fi basics like advantages, limitations, applications and future scope