Channel, Phase Noise, and Frequency Offset in OFDM Systems: Joint Estimation, Data Detection, and Hybrid Cramer-Rao Lower Bound

Oscillator phase noise (PHN) and carrier frequency offset (CFO) can adversely impact the performance of orthogonal frequency division multiplexing (OFDM) systems, since they can result in inter carrier interference and rotation of the signal constellation. In this paper, we propose an expectation conditional maximization (ECM) based algorithm for joint estimation of channel, PHN, and CFO in OFDM systems. We present the signal model for the estimation problem and derive the hybrid Cramer-Rao lower bound (HCRB) for the joint estimation problem. Next, we propose an iterative receiver based on an extended Kalman filter for joint data detection and PHN tracking. Numerical results show that, compared to existing algorithms, the performance of the proposed ECM-based estimator is closer to the derived HCRB and outperforms the existing estimation algorithms at moderate-to-high signal-to-noise ratio (SNR). In addition, the combined estimation algorithm and iterative receiver are more computationally efficient than existing algorithms and result in improved average uncoded and coded bit error rate (BER) performance

Channel, Phase Noise, and Frequency Offset in OFDM Systems: Joint Estimation, Data Detection, and Hybrid Cramer-Rao Lower Bound

Oscillator phase noise (PHN) and carrier frequency offset (CFO) can adversely impact the performance of orthogonal frequency division multiplexing (OFDM) systems, since they can result in inter carrier interference and rotation of the signal constellation. In this paper, we propose an expectation conditional maximization (ECM) based algorithm for joint estimation of channel, PHN, and CFO in OFDM systems. We present the signal model for the estimation problem and derive the hybrid Cramer-Rao lower bound (HCRB) for the joint estimation problem. Next, we propose an iterative receiver based on an extended Kalman filter for joint data detection and PHN tracking. Numerical results show that, compared to existing algorithms, the performance of the proposed ECM-based estimator is closer to the derived HCRB and outperforms the existing estimation algorithms at moderate-to-high signal-to-noise ratio (SNR). In addition, the combined estimation algorithm and iterative receiver are more computationally efficient than existing algorithms and result in improved average uncoded and coded bit error rate (BER) performance.ARC Discovery Projects Grant DP14010113

Mechanical properties of concrete containing palm oil fuel ash and modified expanded polystyrene beads as replacement materials using finite element method

Nowadays, so much waste material was dumped and produced by the industrial sector. In this research, the Palm Oil Fuel Ash (POFA) and Modified Expanded Polystyrene beads (EPS) were used as replacement material. The purpose of this research was to focus on replacement of the modified expanded polystyrene beads (EPS) as a fine aggregate and the palm oil fuel ash (POFA) as a cement in term of mechanical properties of concrete. For Modified EPS will replace with aggregate from 10.0 % and 20.0 % While, for POFA will replace with cement from 10.0 %, 20.0 % and 30.0 %. The data of the material replacement for POFA and Modified EPS will be taken from previous study. Furthermore, the concrete cubes will be analyzed using software called ABAQUS. ABAQUS software is used because this software can measure the concrete cubes in such detail. This test will be performed on a cube that has reached the age of 28 days by following the previous experimental results. In addition, the software can also validate the work for the stress and strain of the graph by analyzing the concrete cubes. Information on Modified EPS and POFA can be filled in this software. Furthermore, it can also analyze mechanical properties of concrete that containing. Modified EPS and POFA. Indirectly, this will help compare the strength of concrete cube that containing of Modified EPS and POFA

A simulation model of reinforced concrete beam containing expanded polystyrene beads (EPS) and palm oil fueled ash (POFA) using finite element method

In this study, Expanded Polystyrene bead (EPS) and Palm Oil Fuelled Ash (POFA) will be used to replace several percents of cement and aggregate in reinforced concrete beam construction. EPS can produce lightweight concrete, and the use of POFA can produce high strength concrete and can also reduce waste disposal. The reinforced concrete beams were analysed using computer software called ABAQUS. The main reason Abaqus software is used as analytics software for this project is that the software is designed specifically for analyzing advanced structural and heat transfer. It is designed for both linear and nonlinear pressure analyses for both tiny and huge structures. This software can also be used to analyze the proposed reinforced concrete beam failure pattern of EPS and POFA. The percentage of EPS and POFA were 40% to 60% in concrete as replacement material. The information obtained from Abaqus is then used to verify the experimental results. The data also contains the appropriate percentage of EPS and POFA in the reinforced concrete beam where performance in terms of bending, pressure, and failure pattern is at maximum. The result shows decrease performance of RC beam containing 40-60% EPS and POFA

Insomnia in chronic renal patients on dialysis in Saudi Arabia

<p>Abstract</p> <p>Background</p> <p>Studies have shown that insomnia is a common sleep disorder among patients with end-stage renal disease (ESRD). This study aimed to assess the prevalence of insomnia in Saudi patients with ESRD who are on maintenance dialysis.</p> <p>Methods</p> <p>This was an observational cross-sectional study carried out over a period of five months in two hemodialysis centers in Saudi Arabia. To assess the prevalence of insomnia, we used the ICSD-2 definition. We also examined the association between insomnia and other sleep disorders, the underlying causes of renal failure, dialysis duration, dialysis shift, and other demographic data.</p> <p>Results</p> <p>Out of 227 enrolled patients, insomnia was reported by 60.8%. The mean patient age was 55.7 ± 17.2 years; 53.7% were male and 46.3% were female. Insomnia was significantly associated with female gender, afternoon hemodialysis, Restless Legs Syndrome, high risk for obstructive Sleep Apnea Syndrome and excessive daytime sleepiness (<it><b>P-values: </b></it>0.05, 0.01, < 0.0001, < 0.0001, and < 0.0001, respectively). No significant association was found between insomnia and other variables, including BMI, smoking habits, underlying etiology of renal failure, dialysis duration, association with hemoglobin, ferritin, and phosphorus or dialysis adequacy as measured by the Kt/V index.</p> <p>Conclusion</p> <p>Insomnia is common in dialysis patients and was significantly associated with other sleep disorders. Greater attention needs to be given to the care of dialysis patients with regard to the diagnosis and management of insomnia and associated sleep disorders.</p

Evaluation of aspirin and statin therapy use and adherence in patients with premature atherosclerotic cardiovascular disease

Importance: Studies on the use of and adherence to secondary prevention therapies in patients with premature and extremely premature atherosclerotic cardiovascular disease (ASCVD) are lacking.Objective: To evaluate and compare aspirin use, any statin use, high-intensity statin use, and statin adherence among patients with premature or extremely premature ASCVD compared with patients with nonpremature ASCVD.Design, setting, and participants: This multicenter cross-sectional study used the clinical and administrative data sets of the US Department of Veterans Affairs (VA) to identify adult patients with at least 1 primary care visit in the VA health care system between October 1, 2014, and September 30, 2015. The study cohort comprised patients with ASCVD (ischemic heart disease, peripheral arterial disease, or ischemic cerebrovascular disease) who were enrolled in the Veterans With Premature Atherosclerosis (VITAL) registry. Patients with missing data for date of birth or sex and those with limited life expectancy were excluded. Data were analyzed from November 1, 2019, to January 1, 2020.Exposures: Premature (the first ASCVD event occurred at age women) vs nonpremature (the first ASCVD event occurred at age ≥55 years for men or age ≥65 years for women) ASCVD and extremely premature (the first ASCVD event occurred at age \u3c40 \u3eyears) vs nonpremature ASCVD.Main outcomes and measures: The primary outcomes were aspirin use, any statin use, high-intensity statin use, and statin adherence (measured by proportion of days covered [PDC] ≥0.8).Results: Of the 1 248 158 patients identified, 135 703 (10.9%) had premature ASCVD (mean [SD] age, 49.6 [5.8] years; 116 739 men [86.0%]), 1 112 455 (89.1%) had nonpremature ASCVD (mean [SD] age, 69.6 [8.9] years; 1 104 318 men [99.3%]), and 7716 (0.6%) had extremely premature ASCVD (mean [SD] age, 34.2 [4.3] years; 6576 men [85.2%]). Patients with premature ASCVD vs those with nonpremature ASCVD had lower rates of aspirin use (96 468 [71.1%] vs 860 726 [77.4%]; P \u3c .001) and any statin use (98 908 [72.9%] vs 894 931 [80.5%]; P \u3c .001); had a statin PDC of 0.8 or higher (57 306 [57.9%] vs 644 357 [72.0%]; P \u3c .001); and a higher rate of high-intensity statin use (49 354 [36.4%] vs 332 820 [29.9%]; P \u3c .001). Similarly, patients with extremely premature ASCVD were less likely to use aspirin (odds ratio [OR], 0.27; 95% CI, 0.26-0.29), any statin (OR, 0.25; 95% CI, 0.24-0.27), or high-intensity statin (OR, 0.78; 95% CI, 0.74-0.82) and to be statin adherent (OR, 0.44; 95% CI, 0.41-0.47).Conclusions and relevance: In this study, patients with premature or extremely premature ASCVD appeared to be less likely to use aspirin or statins and to adhere to statin therapy. This finding warrants further investigation into premature ASCVD and initiatives, including clinician and patient education, to better understand and mitigate the disparities in medication use and adherence

Frequency and Practice-Level Variation in Inappropriate Aspirin Use for the Primary Prevention of Cardiovascular Disease Insights From the National Cardiovascular Disease Registry’s Practice Innovation and Clinical Excellence Registry

AbstractBackgroundAmong patients without cardiovascular disease (CVD) and low 10-year CVD risk, the risks of gastrointestinal bleeding and hemorrhagic strokes associated with aspirin use outweigh any potential atheroprotective benefit. According to the guidelines on primary prevention of CVD, aspirin use is considered appropriate only in patients with 10-year CVD risk ≥6% and inappropriate in patients with 10-year CVD risk <6%.ObjectivesThe goal of this study was to examine the frequency and practice-level variation in inappropriate aspirin use for primary prevention in a large U.S. nationwide registry.MethodsWithin the National Cardiovascular Disease Registry’s Practice Innovation and Clinical Excellence registry, we assessed 68,808 unique patients receiving aspirin for primary prevention from 119 U.S. practices. The frequency of inappropriate aspirin use was determined for primary prevention (aspirin use in those with 10-year CVD risk <6%). Using hierarchical regression models, the extent of practice-level variation using the median rate ratio (MRR) was assessed.ResultsInappropriate aspirin use frequency was 11.6% (7,972 of 68,808) in the overall cohort. There was significant practice-level variation in inappropriate use (range 0% to 71.8%; median 10.1%; interquartile range 6.4%) for practices; adjusted MRR was 1.63 (95% confidence interval [CI]: 1.47 to 1.77). Results remained consistent after excluding 21,052 women age ≥65 years (inappropriate aspirin use 15.2%; median practice-level inappropriate aspirin use 13.8%; interquartile range 8.2%; adjusted MRR 1.61 [95% CI: 1.46 to 1.75]) and after excluding patients with diabetes (inappropriate aspirin use 13.9%; median practice-level inappropriate aspirin use 12.4%; interquartile range 7.6%; adjusted MRR 1.55 [95% CI: 1.41 to 1.67]).ConclusionsMore than 1 in 10 patients in this national registry were receiving inappropriate aspirin therapy for primary prevention, with significant practice-level variations. Our findings suggest that there are important opportunities to improve evidence-based aspirin use for the primary prevention of CVD

Methodological rigor and temporal trends of cardiovascular medicine meta-analyses in highest-impact journals

Background Well-conducted meta-analyses are considered to be at the top of the evidence-based hierarchy pyramid, with an expansion of these publications within the cardiovascular research arena. There are limited data evaluating the trends and quality of such publications. The objective of this study was to evaluate the methodological rigor and temporal trends of cardiovascular medicine-related meta-analyses published in the highest impact journals. Methods and Results Using the Medline database, we retrieved cardiovascular medicine-related systematic reviews and meta-analyses published i

Characteristics of x-ray attenuation in electrospun bismuth oxide/polylactic acid nanofibre mats

The characteristics of the X-ray attenuation in electrospun nano(n)- and micro(m)-Bi2O3/polylactic acid (PLA) nanofibre mats with different Bi2O3 loadings were compared as a function of energy using mammography (i.e. tube voltages of 22–49 kV) and X-ray absorption spectroscopy (XAS) (7–20 keV). Results indicate that X-ray attenuation by electrospun n-Bi2O3/PLA nanofibre mats is distinctly higher than that of m-Bi2O3/PLA nanofibre mats at all energies investigated. In addition, with increasing filler loading (n-Bi2O3 or m-Bi2O3), the porosity of the nanofibre mats decreased, thus increasing the X-ray attenuation, except for the sample containing 38 wt% Bi2O3 (the highest loading in the present study). The latter showed higher porosity, with some beads formed, thus resulting in a sudden decrease in the X-ray attenuation