Extremely High Frequency Resolution and Low Harmonic Distortion Digital Look-Up-Table Sinusoidal Oscillators

New techniques to efficiently increase the frequency resolution of digital sinusoidal oscillators based on look-up-table (LUT) methods are proposed. The increase in frequency resolution is achieved while maintaining very low level of spurious harmonic distortion. The proposed techniques increase the LUT length to a level at which the spurious harmonic distortion is negligible. The first proposed technique is based on partitioning the address register into three sets and dividing the available LUT length into three smaller tables addressed according to the content of the address register sets. The second proposed technique utilizes one LUT and interpolates the values of the samples that are not stored in the table. The third proposed technique is similar to the first technique with the advantage of simpler implementation and lower levels of spurious harmonic distortion. The proposed techniques are simulated and their performance is compared with that of the direct LUT and trigonometric interpolation methods. The simulation results show that the proposed techniques are superior to both direct LUT and trigonometric interpolation methods

Survey of CT radiation doses and iodinated contrast medium administration: an international multicentric study

ObjectiveTo assess the relationship between intravenous iodinated contrast media (ICM) administration usage and radiation doses for contrast-enhanced (CE) CT of head, chest, and abdomen-pelvis (AP) in international, multicenter settings. MethodsOur international (n = 16 countries), multicenter (n = 43 sites), and cross-sectional (ConRad) study had two parts. Part 1: Redcap survey with questions on information related to CT and ICM manufacturer/brand and respective protocols. Part 2: Information on 3,258 patients (18-96 years; M:F 1654:1604) who underwent CECT for a routine head (n = 456), chest (n = 528), AP (n = 599), head CT angiography (n = 539), pulmonary embolism (n = 599), and liver CT examinations (n = 537) at 43 sites across five continents. The following information was recorded: hospital name, patient age, gender, body mass index [BMI], clinical indications, scan parameters (number of scan phases, kV), IV-contrast information (concentration, volume, flow rate, and delay), and dose indices (CTDIvol and DLP). ResultsMost routine chest (58.4%) and AP (68.7%) CECT exams were performed with 2-4 scan phases with fixed scan delay (chest 71.4%; AP 79.8%, liver CECT 50.7%) following ICM administration. Most sites did not change kV across different patients and scan phases; most CECT protocols were performed at 120-140 kV (83%, 1979/2685). There were no significant differences between radiation doses for non-contrast (CTDIvol 24 [16-30] mGy; DLP 633 [414-702] mGycm) and post-contrast phases (22 [19-27] mGy; 648 [392-694] mGycm) (p = 0.142). Sites that used bolus tracking for chest and AP CECT had lower CTDIvol than sites with fixed scan delays (p < 0.001). There was no correlation between BMI and CTDIvol (r2 <= - 0.1 to 0.1, p = 0.931). ConclusionOur study demonstrates up to ten-fold variability in ICM injection protocols and radiation doses across different CT protocols. The study emphasizes the need for optimizing CT scanning and contrast protocols to reduce unnecessary contrast and radiation exposure to patients. Clinical relevance statementThe wide variability and lack of standardization of ICM media and radiation doses in CT protocols suggest the need for education and optimization of contrast usage and scan factors for optimizing image quality in CECT

A Novel Coherent Digital Sweep Oscillator with Extremely Low Sweep Rates and Harmonic Distortion

A novel technique to efficiently increase the resolution of coherent digital sweep oscillators based on look-up-table (LUT) methods is proposed. The increase in resolution measured in terms of sweep rates is achieved while maintaining very low levels of spurious harmonic distortion. The proposed technique increases the LUT length to a level at which the spurious harmonic distortion is negligible. The proposed technique is based on partitioning the address register into three sets and dividing the available LUT length into five smaller tables addressed according to the content of the three address register sets. The proposed technique is simulated and its performance is compared with that of the known sweep oscillators. The simulation results show that the proposed technique is superior to all sweep oscillators reported in the literature

Cooperative Space Time Coding for Semi Distributed Detection in Wireless Sensor Networks

Parallel distributed detection in wireless sensor networks (WSNs) is considered in this paper. In parallel architecture, sensors process the observations to make local decisions and send them to a central device called fusion center. Parallel architecture is assumed in this paper with cooperative sensors in order to obtain Alamouti space time block codes (STBCs). A similar idea was discussed by Vosoughi and Ahmadi (2009). Although the likelihood ratio provided in that paper is correct, the simulation results don’t make sense. In this paper, we are going to prove that the results provided in (Vosoughi &amp; Ahmadi, 2009) are not correct. Upper bound for the detection performance is also derived. Furthermore, suboptimal fusion rules are derived to support our results. Moreover, correct results are shown in this paper.</p

Spot Welding of 6061 Aluminum Alloy by Friction Stir Spot Welding Process

This study was focused on the effect of welding parameters on the lap-shear fracture load of the welded joints prepared by friction stir spot welding. Four different weld parameters were analyzed: rotational speed, dwell time, pin length and shoulder size of the welding tool. It was found that the lap-shear fracture load increases with an increase of the welding parameters to a limited value and decreases with further increase. The strong welded joints failed under nugget-pull out fracture

Stress Hyperglycemia Ratio as a Prognostic Marker in Diabetic Patients Hospitalized with COVID-19

Evidence is conflicting about the diabetes characteristics associated with worse outcome among hospitalized COVID-19 patients. We aimed to assess the role of stress hyperglycemia ratio (SHR) as a prognostic marker among them. In our retrospective cohort study, patients were stratified according to SHR, admission glucose, and glycated hemoglobin tertiles. The primary outcome was a composite endpoint of invasive mechanical ventilation, intensive care unit admission, and in-hospital mortality. The study included 395 patients with a mean age of 59 years, and 50.1% were males. Patients in the third tertile of SHR developed more primary events, and the difference was significant compared to the first tertile (p = 0.038) and close to significance compared to the second tertile (p = 0.054). There was no significant difference in the outcomes across admission glucose and glycated hemoglobin tertiles. A higher SHR tertile was an independent risk factor for the primary outcome (OR, 1.364; 95% CI: 1.014&ndash;1.836; p = 0.040) after adjustment for other covariables. In hospitalized COVID-19 diabetic patients, SHR third tertile was significantly associated with worse outcome and death. SHR can be a better prognostic marker compared to admission glucose and glycated hemoglobin. A higher SHR was an independent risk factor for worse outcome and in-hospital mortality

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods: The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results: NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion: As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background: Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods: The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results: A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion: Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)