Multivariable Techniques Research Articles

Determinants of incomplete vaccination among children 12-23 months in Nigeria: An analysis of a national sample.

The study aimed to assess the prevalence and the determinants of incomplete childhood vaccination in Nigeria. The data for this study was the 2018 Nigeria Demographic and Health Survey. Multivariable multilevel logistic regression analysis techniques using Stata statistical software (version 13) were used in analyzing the data of 5,384 children aged 12-23 months old. About 69.6% of the children were incompletely vaccinated. Individual-level factors such as maternal education, household wealth were associated with incomplete vaccination. The odds of incomplete vaccination among children of mothers without education was 68% higher than those with secondary education and above (adjusted odds ratio [AOR]: (AOR = 1.68; 95% confidence intervals [CI]: 1.56-2.56). Equally children from high wealth index have reduced odds of incomplete vaccination compared to those from low wealth index (AOR = 0.58; 95% CI: 0.47-0.71). Community-level factors such as place of residence, difficulty in getting to health facility were equally associated with vaccination status. The likelihood of incomplete vaccination was 26% higher among children whose parents had difficulty reaching the health facility (AOR = 1.26; 95% CI: 1.11-1.50) than those that did not. In addition, the likelihood of been incompletely vaccinated reduced for children whose mothers live in urban areas (AOR = 0.47; 95% CI: 0.40-0.59). Incomplete childhood vaccination is prevalent in the country and associated with various individual and community factors. Program and policies aimed at improving childhood vaccination uptake should target the identified factors.

Mortality and morbidity in non-transfusable and transfusable patients: A systematic review and meta-analysis.

Mortality and morbidity in non-transfusable and transfusable patients: A systematic review and meta-analysis.

Systemic Racism in Police Killings: New Evidence from the Mapping Police Violence Database, 2013-2021.

This research note provides new evidence consistent with systemic anti-Black racism in police killings across the United States. Data come from the Mapping Police Violence Database (2013-2021). I calculate race-specific odds and probabilities that victims of police killings exhibited mental illness, were armed with a weapon, or attempted to flee the scene at the time of their killing. Multilevel, multivariable logistic regression techniques are applied to further account for the victim's age, gender, year of killing, and geographical clustering. I find that White victims are underrepresented, and Black victims overrepresented in the database. Relative to White victims, Black victims also have 60% lower odds of exhibiting signs of mental illness, 23% lower odds of being armed, and 28% higher odds of fleeing. Hispanic victims exhibit 45% lower odds of being armed relative to their White peers but are otherwise comparable. These patterns persist regardless of the victim's age, gender, year of killing, or geographical location (zip code, state, and neighborhood type). Thus, the threshold for being perceived as dangerous, and thereby falling victim to lethal police force, appears to be higher for White civilians relative to their Black or Hispanic peers. Current findings provide empirical support for political initiatives to curb lethal police force, as such efforts could help to reduce racial disparities in deaths by police nationwide.

Coherent self-control of free-space optical beams with integrated silicon photonic meshes

In technologies operating at light wavelengths for wireless communication, sensor networks, positioning, and ranging, a dynamic coherent control and manipulation of light fields is an enabling element for properly generating and correctly receiving free-space optical (FSO) beams even in the presence of unpredictable objects and turbulence in the light path. In this work, we use a programmable mesh of Mach–Zehnder (MZI) interferometers to automatically control the complex field radiated and captured by an array of optical antennas. The implementation of local feedback control loops in each MZI stage, without global multivariable optimization techniques, enables an unlimited scalability. Several functionalities are demonstrated, including the generation of perfectly shaped beams with nonperfect optical antennas, the imaging of a desired field pattern through an obstacle or a diffusive medium, and the identification of an unknown obstacle inserted in the FSO path. Compared to conventional devices used for the manipulation of FSO beams, such as spatial light modulators, our programmable device can self-configure through automated control strategies and can be integrated with other functionalities implemented onto the same photonic chip.

Hybrid generation of renewables increases the energy system's robustness in a changing climate

Hybrid generation of renewables (e.g., hydro, solar, and wind energy sources) is an increasingly important technology to improve energy use efficiency and reliability. However, renewables are usually influenced by climate factors. In a changing climate, it is essential to know whether the integration of renewables enhances or weakens the robustness of the energy system, which is defined as “the insensitivity of the system's operational performances to climate change”. To answer this question, we first modeled the long-term operation of several hybrid renewable energy systems (HRESs) (i.e., hydro–solar–wind, hydro–wind, and hydro–solar systems) and a hydropower energy system using historical hydro-meteorological data and stochastic dynamic programming. Then, we constructed uncertain climatic conditions using a multi-variable stochastic simulation technique, which considered spatial-temporal correlations between inflow, solar, and wind power output. Finally, we compared the robustness of the operating rules under the simulated climatic conditions. A hypothetical case study based on China's Longyangxia hydro–photovoltaic (PV) power plant showed that: (1) the integration of PV and/or wind power significantly improved the system's robustness compared to only hydropower sources under uncertain climatic conditions; (2) the hydro–solar–wind HRES was the most robust system, meeting the energy demand more than 90% of the climatic conditions; (3) the hydro–solar–wind HRES was most sensitive to inflow change, followed by changes to wind and PV power. These findings hightlight the importance to implement hybrid generation of hydro, solar, and wind energy sources in a changing climate.

Approximate Solutions of Nonlinear Partial Differential Equations Using B-Polynomial Bases

A multivariable technique has been incorporated for guesstimating solutions of Nonlinear Partial Differential Equations (NPDE) using bases set of B-Polynomials (B-polys). To approximate the anticipated solution of the NPD equation, a linear product of variable coefficients ai(t) and Bi(x) B-polys has been employed. Additionally, the variable quantities in the anticipated solution are determined using the Galerkin method for minimizing errors. Before the minimization process is to take place, the NPDE is converted into an operational matrix equation which, when inverted, yields values of the undefined coefficients in the expected solution. The nonlinear terms of the NPDE are combined in the operational matrix equation using the initial guess and iterated until converged values of coefficients are obtained. A valid converged solution of NPDE is established when an appropriate degree of B-poly basis is employed, and the initial conditions are imposed on the operational matrix before the inverse is invoked. However, the accuracy of the solution depends on the number of B-polys of a certain degree expressed in multidimensional variables. Four examples of NPDE have been worked out to show the efficacy and accuracy of the two-dimensional B-poly technique. The estimated solutions of the examples are compared with the known exact solutions and an excellent agreement is found between them. In calculating the solutions of the NPD equations, the currently employed technique provides a higher-order precision compared to the finite difference method. The present technique could be readily extended to solving complex partial differential equations in multivariable problems.

A quadrilateral optimization method for non-linear thermal properties determination in materials at high temperatures

The actual experimental methods applied to determine the materials' thermal properties at high temperatures usually do not provide good quality values for matching simulations to experimental data. To solve this problem, this work proposes an alternative inverse methodology to estimate the thermal properties of a material at high temperatures. The developed technique is called Quadrilateral Optimization Method (QOM). The QOM is a multivariable estimation technique developed to determine the function's parameters. To regularize the results, the Time Traveling Regularization (TTR) was applied in the objective function. To prove the methodology efficiency, the specific heat is estimated through this inverse approach for a LASER welding problem. In this case, the specific heat was treated as an exponential function. Then, the QOM estimates the parameters of this function. A sensitivity analysis is performed to determine the estimation range. To minimize the computational time, in the direct model the non-linear heat diffusion equation was solved through the Finite Volume Method in an in-house CUDA-C code. A numerical welding experiment was performed to eliminate the real experimental errors. The results demonstrated that the proposed approach had an average error of less than 0.075% in the parameters' estimation in the best-case-scenario. The new methodology was validated, and it proved to be an easier and cheaper way to determine the thermal properties at high temperatures without the need to use advanced experimental apparatus.

Management of superficial venous thrombosis based on individual risk profiles: protocol for the development and validation of three prognostic prediction models in large primary care cohorts

BackgroundSuperficial venous thrombosis (SVT) is considered a benign thrombotic condition in most patients. However, it also can cause serious complications, such as clot progression to deep venous thrombosis (DVT) and pulmonary embolism (PE). Although most SVT patients are encountered in primary healthcare, studies on SVT nearly all were focused on patients seen in the hospital setting. This paper describes the protocol of the development and external validation of three prognostic prediction models for relevant clinical outcomes in SVT patients seen in primary care: (i) prolonged (painful) symptoms within 14 days since SVT diagnosis, (ii) for clot progression to DVT or PE within 45 days and (iii) for clot recurrence within 12 months.MethodsData will be used from four primary care routine healthcare registries from both the Netherlands and the UK; one UK registry will be used for the development of the prediction models and the remaining three will be used as external validation cohorts. The study population will consist of patients ≥18 years with a diagnosis of SVT. Selection of SVT cases will be based on a combination of ICPC/READ/Snowmed coding and free text clinical symptoms. Predictors considered are sex, age, body mass index, clinical SVT characteristics, and co-morbidities including (history of any) cardiovascular disease, diabetes, autoimmune disease, malignancy, thrombophilia, pregnancy or puerperium and presence of varicose veins. The prediction models will be developed using multivariable logistic regression analysis techniques for models i and ii, and for model iii, a Cox proportional hazards model will be used. They will be validated by internal-external cross-validation as well as external validation.DiscussionThere are currently no prediction models available for predicting the risk of serious complications for SVT patients presenting in primary care settings. We aim to develop and validate new prediction models that should help identify patients at highest risk for complications and to support clinical decision making for this understudied thrombo-embolic disorder. Challenges that we anticipate to encounter are mostly related to performing research in large, routine healthcare databases, such as patient selection, endpoint classification, data harmonisation, missing data and avoiding (predictor) measurement heterogeneity.

Epidemiology of intravenous immune globulin in septic shock: a retrospective cohort analysis of the Premier Healthcare Database.

Intravenous immune globulin (IVIG) may improve survival in people with septic shock. Current utilization patterns of IVIG are unknown. We sought to characterize adult patients with septic shock requiring vasopressors who received IVIG, describes IVIG regimens, and evaluate determinants of IVIG use in patients with septic shock. We conducted a retrospective database study of adult patients with septic shock admitted to US hospitals in the Premier Healthcare Database (from July 2010 to June 2013). We described the proportion of patients with septic shock receiving IVIG, examined IVIG regimens across sites and employed random-effects multivariable regression techniques to identify predictors of IVIG use. Intravenous immune globulin was administered to 0.3% (n = 685) of patients with septic shock; with a median [interquartile range (IQR)] dose of 1 [0.5-1.8] g·kg-1 for a median [IQR] of 1 [1-2] day. Receipt of IVIG was less likely for Black patients (odds ratio [OR], 0.54; 95% confidence interval [CI] 0.41 to 0.72) and patients without private insurance (Medicare OR, 0.73; 95% CI 0.59 to 0.90; Medicaid OR, 0.41; 95% CI 0.30 to 0.57) and more likely for patients with immunocompromise (OR, 6.83; 95% CI 5.47 to 8.53), necrotizing fasciitis (OR, 9.78; 95% CI 6.97 to 13.72), and toxic shock (OR, 56.9; 95% CI 38.7 to 83.7). Intravenous immune globulin is used infrequently across the US in patients with septic shock. Regimens of IVIG in septic shock may be less intensive than those associated with a survival benefit in meta-analyses. Observed infrequent use supports apparent clinical equipoise, perhaps secondary to limitations of the primary literature. A clinical trial evaluating the role of IVIG in septic shock is needed.

Health Data Management Practice and Associated Factors Among Health Professionals Working at Public Health Facilities in Resource Limited Settings.

BackgroundDespite the vast amount of resources invested in the development of health information systems, health professionals in developing countries are still suffering from lack of adequate skill to perform health data management activities. There is a lack of sound evidence to overcome health data management challenges in this setting. This study aimed to assess health data management practice and its associated factors among health professionals working at public health facilities in North Wollo Zone, Northeast Ethiopia.MethodsA quantitative cross-sectional study was conducted at public health facilities in North Wollo Zone, Northeast Ethiopia from March 2 to April 15, 2020. A total of 715 health professionalswere selected using a stratified random sampling technique. EpiData version 4.6 and STATA version 15 were used for data entry and analysis, respectively. Descriptive statistics were computed. Multi-variable logistic regression analyses techniques were carried out to show the association between explanatory and outcome variables. Odd ratio at 95% confidence level was used to describe the strength of association.ResultsA total of 643 health professionals participated in this study. The response rate was 90%. Among them, 56.1% (95% CI: 52.3%–59.9%) demonstrated good data management practice. Working in health center [AOR=1.31 (95% CI: 1.853, 2.003)], having knowledge on data management [AOR=3.74 (95% CI: 2.454, 5.713)], favorable attitude toward data management [AOR=2.64 (95% CI: 1.746, 3.976)], high competency level on data management tasks [AOR=3.12 (95% CI: 1.873, 5.197)], friendliness of data management format [AOR=2.26 (95% CI: 1.478, 3.454)], supervision [AOR=1.78 (95% CI: 1.153, 2.745)] and training [AOR=1.84 (95% CI: 1.115, 3.022)] were significantly associated with good practice of health data management.ConclusionHealth data management practices of health professionals’ were found to be inadequate. Capacity building to enhance health professionals’ data management knowledge, attitude and their competency level, providing continuous supportive supervision, designing friendly data management format, providing comprehensive data management training are necessary measures to improve data management practice in this study setting.

Recurrence and colon cancer-specific death in patients with large bowel obstruction requiring urgent operation: a competing risks analysis.

Clinical presentation with large bowel obstruction has been proposed as a predictor of poor long-term oncological outcomes after resection for colorectal cancer. This study examines the association between obstruction and recurrence and cancer-specific death after resection for colon cancer. Consecutive patients who underwent resection for colon cancer between 1995 and 2014 were drawn from a prospectively recorded hospital database with all surviving patients followed for at least 5years. The outcomes of tumour recurrence and colon cancer-specific death were assessed by competing risks multivariable techniques with adjustment for potential clinical and pathological confounding variables. Recurrence occurred in 271 of 1485 patients who had a potentially curative resection. In bivariate analysis, obstruction was significantly associated with recurrence [hazard ratio (HR) 2.23, CI 1.52-3.26, p<0.001] but this association became nonsignificant after adjustment for confounders (HR 1.53, CI 0.95-2.46, p=0.080). Colon cancer-specific death occurred in 238 of 295 patients who had a noncurative resection. Obstruction was not significantly associated with cancer-specific death (HR 1.02, CI 0.72-1.45, p=0.903). In patients who had a noncurative resection, the competing risks incidence of colon cancer-specific death was not significantly greater in obstructed than in unobstructed patients (HR 1.02, CI 0.72-1.45, p=0.903). Whilst the immediate clinical challenge of an individual patient presenting with large bowel obstruction must be addressed by the surgeon, the patient's long-term oncological outcomes are unrelated to obstruction per se.

Implementation of a Surgical Intensivist Model Increases Palliative Care Consultation in the Care of Trauma ICU Patients.

This study investigated patient outcomes of care before and after transitioning to a surgical intensivist-led trauma-intensive care unit (ICU) team. The intensivist team provided daily multidisciplinary rounds and continuity of care. Prior to an intensivist model, general surgeons cared for trauma patients admitted to the unit. Outcomes of 1,078 trauma patients, admitted to the ICU at a Level II trauma center, under care of general surgeons (1/2011-8/2012, n = 449) were retrospectively compared with care managed by a surgical intensivist team (1/2013-5/2015, n = 629) by Pearson Chi-squared and Wilcoxon tests. A multivariable logistic regression technique was used to control for covariates. Demographics and injury severity were analyzed. The primary outcome was ICU mortality. The secondary outcomes were length of stay (LOS), ventilator-free and ICU-free days, and ICU readmission rate. Other data collected included palliative care consultation. Results: There were no statistically significant differences in ICU mortality (P = 0.055), hospital LOS (P = 0.481), ventilator-free days (P = 0.174), or ICU readmission rate (P = 0.587). The surgical intensivist team consulted palliative care more frequently (4.0% vs 13.5%, P < 0.001), while managing more trauma patients who were older than 65 years (P < 0.001) with lower Glasgow Coma Scale (P = 0.048) and higher injury severity (P = 0.025) and abbreviated injury scale (P < 0.001) scores. There were no differences in outcomes. However, incorporating palliative care consultation in the ICU is essential in the support of critically ill patients and their families. These data demonstrate that a surgical intensivist team utilized palliative care more often in the management of trauma patients admitted to the ICU.

Exploring the socio-economic determinants of educational inequalities in diarrhoea among under-five children in low- and middle-income countries: a Fairlie decomposition analysis

BackgroundWhat explains the underlying causes of educational inequalities in diarrhoea among under-five children in low- and middle-income countries (LMIC) is poorly exploited, operationalized, studied and understood. This paper aims to assess the magnitude of educational-related inequalities in the development of diarrhoea and decompose risk factors that contribute to these inequalities among under-five children (U5C) in LMIC.MethodsSecondary data of 796,150 U5C from 63,378 neighbourhoods in 57 LMIC was pooled from the Demographic and Health Surveys (DHS) conducted between 2010 and 2019. The main determinate variable in this decomposition study was mothers’ literacy levels. Descriptive and inferential statistics comprising of bivariable analysis and binary logistic multivariable Fairlie decomposition techniques were employed at p = 0.05.ResultsOf the 57 countries, we found a statistically significant pro-illiterate odds ratio in 6 countries, 14 showed pro-literate inequality while the remaining 37 countries had no statistically significant educational-related inequality. The countries with pro-illiterate inequalities are Burundi (OR = 1.11; 95% CI: 1.01–1.21), Cameroon (OR = 1.84; 95% CI: 1.66–2.05), Egypt (OR = 1.26; 95% CI: 1.12–1.43), Ghana (OR = 1.24; 95% CI: 1.06–1.47), Nigeria (OR = 1.80; 95% CI: 1.68–1.93), and Togo (OR = 1.21; 95% CI: 1.06–1.38). Although there are variations in factors that contribute to pro-illiterate inequality across the 6 countries, the overall largest contributors to the inequality are household wealth status, maternal age, neighbourhood SES, birth order, toilet type, birth interval and place of residence. The widest pro-illiterate risk difference (RD) was in Cameroon (118.44/1000) while the pro-literate risk difference was widest in Albania (− 61.90/1000).ConclusionsThe study identified educational inequalities in the prevalence of diarrhoea in children with wide variations in magnitude and contributions of the risk factors to pro-illiterate inequalities. This suggests that diarrhoea prevention strategies is a must in the pro-illiterate inequality countries and should be extended to educated mothers as well, especially in the pro-educated countries. There is a need for further studies to examine the contributions of structural and compositional factors associated with pro-educated inequalities in the prevalence of diarrhoea among U5C in LMIC.

Ethnicity-Specific Normative Models of Quadruple Test as a Screening Test for Down Syndrome.

Background and Objectives: To establish normative models for median levels of serum biomarkers of the second trimester quad test (alpha-fetoprotein: AFP; free beta-human gonadotropins: hCG; inhibin-A; and unconjugated estriol: uE3) specific to Thai women and to compare multiples of the median (MoMs) derived from ethnicity-specific models and those derived from Caucasian models with ethnic correction. Materials and Methods: A cross-sectional study was undertaken in a tertiary, medical teaching center among low-risk pregnant Thai women between 14 and 21 weeks of gestation to measure the levels of the four serum biomarkers. The measured values of each biomarker were analyzed using the multivariable factorial polynomial technique for quantile regression as a function of gestational age and maternal weight. Results: The Thai-specific normative models for the four biomarkers were generated and available for use. The MoMs of all individuals generated from our models were significantly different from conventional (Caucasian) models with ethnic correction (Wilcoxon signed-rank test; p < 0.0001 for all biomarkers). The MoMs of AFP and hCG from both methods were in agreement, but those from Thai-specific models were significantly higher. However, those of inhibin-A and uE3 were markedly different and ethnic correction was unlikely to be useful. Conclusions: The Thai-specific normative models of the quad test as a function of gestational age and maternal weight were constructed using multivariable factorial polynomial models, better than simple quantile regression or log-linear regression used in earlier decades. The analysis of MoMs supports the use of ethnicity-specific models instead of Caucasian models with ethnic correction.

Adaptive Predictive Control with Neuro-Fuzzy Parameter Estimation for Microgrid Grid-Forming Converters

Model predictive control (MPC) is a flexible and multivariable control technique with better dynamic performance than linear control. However, MPC is sensitive to parametric mismatches that reduce its control capabilities. In this paper, we present a new method of improving the robustness of MPC to filter parameter variations/mismatches by easily implementable parameter estimation. Furthermore, we extend the proposed technique for wider operating conditions by novel neuro-fuzzy estimation. The results, which are demonstrated by both simulations and real-time hardware-in-the-loop tests, show a steady-state parameter estimation accuracy of 95%, and at least 20% improvement in total harmonic distortion (THD) than conventional non-adaptive MPC under parameter mismatches up to 50% of the nominal values.

Analytic Morphomics Are Related to Outcomes After Lung Volume Reduction Surgery

:Lung volume reduction surgery continues to have a high morbidity despite National Emphysema Treatment Trial selection criteria. This study evaluated the association between analytic morphomics on chest computed tomography scans and outcomes after lung volume reduction surgery. In a retrospective review of 85 lung volume reduction surgery patients from 1998-2013, dorsal muscle group area, subcutaneous and visceral fat area, and bone mineral density were assessed using analytic morphomics. Lung density was divided into five levels of increasing density (Lung density 1, emphysema; 2, normal lung; 4-5, scarring). Outcomes including survival, hospital length of stay, readmission at 30 days, and pulmonary complications were analyzed using univariate and multivariable techniques. Pulmonary complications developed in 27.1% (23/85). Mortality at 90 days was 9.4% (8/85). On multivariable analysis, lower bone mineral density (Odds ratio 0.61; 95% confidence interval 0.39-0.95) was associated with decreased survival, longer length of stay (0.83; 0.77-0.89), and readmissions (0.39; 0.15-1.00). Higher lung density 5:lung density 2 volume (1.84; 1.05-3.23), possibly due to scarring, was associated with pulmonary complications and longer length of stay (1.32; 1.23-1.41) while lower subcutaneous fat area:height was associated with readmissions which may reflect decreased metabolic reserve (0.35; 0.13-0.93). Patients with signs of frailty including lower bone mineral density may be at increased risk of adverse outcomes including decreased survival after lung volume reduction surgery. The results of this hypothesis-generating study will need to be confirmed in larger, multicenter trials to determine whether analytic morphomics can improve risk stratification and patient selection.

Trends and practices for managing low-risk prostate cancer: a SEER-Medicare study.

Expectant management (EM) has been widely recommended for men with low-risk prostatecancers(PCa). We evaluated trends in EM and the sociodemographic and clinical factors associated with EM, initiating a National Comprehensive Cancer Network guideline-concordant active surveillance (AS) monitoring protocol, and switching from EMto active treatment (AT). We used the SEER-Medicare database to identify men ages 66+ diagnosed with a low-risk PCa (PSA < 10 ng/mL, Gleason ≤ 6, stage ≤ T2a) in2010-2013 with ≥1 year of follow-up. We used claims data to capture (1) PCa treatments, including surgical procedures, radiotherapy, and hormone therapy, and (2) AS monitoring procedures, including PSA tests and prostate biopsy. We defined EM as receiving no AT within 1 year of diagnosis. We used multivariable regression techniques to identify factors associated with EM, initiating AS monitoring, and switching to AT. During the study period, EM increased from 29.4% to 49.0%, p < 0.01. Age < 77, being married/partnered, non-Hispanic ethnicity, higher median ZIP code income, lower PSA levels, stage T1c, and more recent year of diagnosis were associated with EM. Nearly 39% of the EM cohort initiated AS monitoring; age <77, White race, being married/partnered, higher median ZIP code income, and lower PSA levels were associated with initiating AS. By three years after diagnosis, 21.3% of the EM cohort had switched to AT, usually after undergoing AS monitoring procedures. We found increasing uptake of EM over time, though over 50% still received AT. About 60% of EM patients did not initiate AS monitoring, even among those with life expectancy >10 years, implying that a substantial proportion was being managed by watchful waiting. AS monitoring was associated with switching to AT, suggesting that treatment decisions likely were based on cancer progression.

A Transported Livengood–Wu Integral Model for Knock Prediction in Computational Fluid Dynamics Simulation

Abstract This work describes the development of a transported Livengood–Wu (L–W) integral model for computational fluid dynamics (CFD) simulation to predict autoignition and engine knock tendency. The currently employed L–W integral model considers both single-stage and two-stage ignition processes, thus can be generally applied to different fuels such as paraffin, olefin, aromatics, and alcohol. The model implementation is first validated in simulations of homogeneous charge compression ignition (HCCI) combustion for three different fuels, showing good accuracy in prediction of autoignition timing for fuels with either single-stage or two-stage ignition characteristics. Then, the L–W integral model is coupled with G-equation model to indicate end-gas autoignition and knock tendency in CFD simulations of a direct-injection spark-ignition engine. This modeling approach is about 10 times more efficient than the ones that based on detailed chemistry calculation and pressure oscillation analysis. Two fuels with same Research Octane Number (RON) but different octane sensitivity are studied, namely, Co-Optima alkylate and Co-Optima E30. Feed-forward neural network model in conjunction with multivariable minimization technique is used to generate fuel surrogates with targets of matched RON, octane sensitivity, and ethanol content. The CFD model is validated against experimental data in terms of pressure traces and heat release rate for both fuels under a wide range of operating conditions. The knock tendency—indicated by the fuel energy contained in the autoignited region—of the two fuels at different load conditions correlates well with the experimental results and the fuel octane sensitivity, implying the current knock modeling approach can capture the octane sensitivity effect and can be applied to further investigation on composition of octane sensitivity.

Neonatal acute kidney injury risk stratification score: STARZ study.

Neonates admitted in the neonatal intensive care unit are vulnerable to acute kidney injury leading to worse outcomes. It is important to identify "at-risk" neonates for early preventive measures. The study was a multicenter, national, prospective cohort study done in 11 centers in India. A multivariable logistic regression technique with step-wise backward elimination method was used, and a "Risk Prediction Scoring" was devised [the STARZ score]. The neonates with admission in the NICU within <25.5 h of birth, requirement of positive pressure ventilation in the delivery room, <28 weeks gestational age, sepsis, significant cardiac disease, urine output <1.32 ml/kg/h or serum creatinine ≥0.98 mg/dl during the first 12 h post admission, use of nephrotoxic drugs, use of furosemide, or use of inotrope had a significantly higher risk of AKI at 7 days post admission in the multivariate logistic regression model. This scoring model had a sensitivity of 92.8%, specificity of 87.4% positive predictive value of 80.5%, negative predictive value of 95.6%, and accuracy of 89.4%. The STARZ neonatal score serves to rapidly and quantitatively determine the risk of AKI in neonates admitted to the neonatal intensive care unit. The STARZ neonatal score serves to rapidly and quantitatively determine the risk of AKI in neonates admitted to the neonatal intensive care unit. These neonates with a higher risk stratification score need intense monitoring and daily kidney function assessment. With this intensification of research in the field of AKI risk stratification prediction, there is hope that we will be able to decrease morbidity and mortality associated with AKI in this population.

End-to-end design of a robust attitude control and vibration suppression system for large space smart structures

The standard approach of controlling in-orbit large flexible structures only by adopting actuators and sensors located at platform level is currently being challenged by new missions’ stringent requirements in terms of demanding guidance profiles and instrument performance. In this perspective, smart materials offer a different solution to improve the performance of space systems by controlling the vibrations of such lightweight structures. In this paper, the problem of designing an end-to-end architecture for active control of large in-orbit structures is addressed. First, a FE model of a large space antenna is derived by using commercial software. The instrument is designed to be supported by an active deployable frame hosting an optimal minimum set of collocated smart actuators and sensors. To this purpose, a comparison among different placement techniques, as Gramian and Modal Strain Energy (MSE) based methods, is proposed to find the final configuration for both actuators and sensors. Attention is paid to create a GNC strategy combining collocated control on flexible appendages with platform control, while minimizing the relative displacements among the most critical points of the antenna. To achieve high performance, Linear Fractional Transformation (LFT) modelling and advanced multivariable techniques are implemented. Finally, to validate the proposed controller, the control system is tested by simulating typical spacecraft manoeuvre profiles.