Performance of free space optical communication using M-array receivers at atmospheric conditions

Abstract: In free space optical (FSO) communication links, atmospheric parameters including absorption, scattering and turbulence have significant impacts on the quality of laser beams propagating through the atmosphere. Absorption and/or scattering, due to atmospheric particles result in optical losses, whereas turbulence contributes to the intensity scintillation that can severely impair the operation of FSO communications systems. In this paper, using a modified model we analyze the atmospheric effects on the signal-to-noise ratio (SNR) and the bit error rate (BER) of an FSO system. We show that there is an improvement in BER when using M-array receivers instead of one a single receiver

Efficient Entanglement Measure for Graph States

In this paper, we study the multipartite entanglement properties of graph states up to seven qubits. Our analysis shows that the generalized concurrence measure is more efficient than geometric entanglement measure for measuring entanglement quantity in the multi-qubit graph states.Comment: 10 pages, 4 table

Validation of the World Health Organization-5 well-being index; assessment of maternal well-being and its associated factors

Objective: The aim of this study was to validate the World Health Organization-5 Well-Being Index (WHO-5) in a sample of pregnant Iranian women, to explore the changes in maternal well-being from pregnancy to postpartum, and to determine the factors associated with maternal well-being. Materials and Methods: This study included 341 pregnant women that presented to healthcare centers affiliated with Shahroud University of Medical Sciences, Iran, in 2011. The participants completed the General Health Questionnaire (GHQ-28) and Farsi version of WHO-5 during the third trimester of pregnancy and at 2 months postpartum. Results: Cronbach's alpha coefficient for WHO-5 items was 0.85. The correlation coefficient between WHO-5 and GHQ-28 was -0.64 (P < 0.001). Exploratory factor analysis yielded 1 factor with an eigen value equal to 3.15, which explained 63.1% of the total variance. Confirmatory factor analysis confirmed the 1-factor structure. The area under ROC curve was 0.82. A WHO-5 cut-off score of <50 exhibited optimal sensitivity (0.84) and specificity (0.59) for identifying psychological symptoms (GHQ-28 score ≥24). There was a significant difference between third trimester (58.4 ± 22) and postpartum (64.1 ± 22.3) mean WHO-5 scores (P < 0.001). Maternal level of education (OR = 1.130; 95% CI: 1.307, 1.232) was the only predictor of maternal well-being during third trimester. Breastfeeding difficulty (OR = 0.923; 95% CI: 0.882, 0.965) and maternal well-being scores during third trimester (OR = 1.038; 95% CI: 1.019, 1.058) were predictors of maternal well-being during the postpartum period. Conclusions: The Farsi version of WHO-5 was observed to be a reliable and valid instrument for screening psychological symptoms in pregnant Iranian women. The present findings show that maternal well-being improved following childbirth

Quality of life after cesarean and vaginal delivery

Objective: Cesarean rates in recent decades have been increasing and a number of studies have shown that cesarean increases maternal morbidities. The aim of this study is to compare the quality of life after cesarean and vaginal delivery. Methods: This prospective study was carried out on 356 pregnant women visiting urban health centers in Shahroud City, Northeast Iran, in 2011. The subjects completed the quality of life questionnaire in the third trimester of pregnancy and at 8 weeks postpartum. Results: In primiparas, the mean global QOL scores for the cesarean and vaginal delivery groups were 67.65±12.7 and 72.12±11.8, respectively. Also, the scores for the physical, psychological and social domains of QOL as well as the global score of QOL were higher in the vaginal delivery group than the cesarean group (p<0.05). In the case of primiparas, multiple regression analysis revealed that after adjusting for education, desirability of pregnancy and the General Health Questionnaire score, the delivery type remained as a predictor of the scores for the physical (R2=1.7%; B=-3.826; p=0.031; CI [-7.301, -.350]) and social (R2=2.5%; B=-5.708; p=0.017; CI [-10.392, -1.023]) domains of QOL and the global QOL score (R2=2.6%; B=-4.065; p=0.006; CI [-6.964, -1.164]). While multiparas, there was no relationship between QOL and type of delivery. Conclusion: In this sample of low-risk women, cesarean negatively affected the QOL of primiparas. More studies with larger sample sizes should be conducted to examine the effects of cesarean on QOL in both primiparas and multiparas within a shorter period after delivery. © OMSB, 2013