Nonlinear model reduction from equations and data.

Modeling in applied science and engineering targets increasingly ambitious objectives, which typically yield increasingly complex models. Despite major advances in computations, simulating such models with exceedingly high dimensions remains a challenge. Even if technically feasible, numerical simulations on such high-dimensional problems do not necessarily give the simplified insight into these phenomena that motivated their initial models. Reduced-order models hold more promise for a quick assessment of changes under parameters and uncertainties, as well as for effective prediction and control. Such models are also highly desirable for systems that are only known in the form of data sets. This focus issue will survey the latest trends in nonlinear model reduction for equations and data sets across various fields of applications, ranging from computational to theoretical aspects.

Nonautonomous spectral submanifolds for model reduction of nonlinear mechanical systems under parametric resonance.

We use the recent theory of spectral submanifolds (SSMs) for model reduction of nonlinear mechanical systems subject to parametric excitations. Specifically, we develop expressions for higher-order nonautonomous terms in the parameterization of SSMs and their reduced dynamics. We provide these results for both general first-order and second-order mechanical systems under periodic and quasiperiodic excitation using a multi-index based approach, thereby optimizing memory requirements and the computational procedure. We further provide theoretical results that simplify the SSM parametrization for general second-order dynamical systems. More practically, we show how the reduced dynamics on the SSM can be used to extract the resonance tongues and the forced response around the principal resonances in parametrically excited systems. In the case of two-dimensional SSMs, we formulate explicit expressions for computing the steady-state response as the zero-level set of a two-dimensional function for systems that are subject to external as well as parametric excitation. This allows us to parallelize the computation of the forced response over the range of excitation frequencies. We demonstrate our results on several examples of varying complexity, including finite-element-type examples of mechanical systems. Furthermore, we provide an open-source implementation of all these results in the software package SSMTool.

Impact of a Mental Health Screening Process in a Pediatric Emergency Department.

OBJECTIVE: The aim of this study was to describe how specific mental health-trained social workers can assist in the evaluations and follow-up of patients presenting with mental health concerns in the pediatric emergency department (ED). METHODS: Work was performed at a quaternary children's hospital ED with 95,000 annual ED visits across 2 locations. Patients requiring mental health services identified based on presenting complaint or from universal suicide screen were included. Emergency department team first evaluates the patients for medical screening and then consults a team of social workers specialized in acute mental health screening (AMHS). The team evaluates and provides recommendation for disposition and assists in plan completion. For patients not admitted, AMHS team makes 24- and 48-hour calls to ensure safety. We collected and analyzed the data on all eligible patients from September 2015 through June 2019 for (1) demographic information, (2) trends in number of consults to AMHS, (3) disposition plans and trends by year, and (4) frequency of follow-up phone calls. RESULTS: A total of 5950 patient visits were reviewed, for 4454 distinct patients. Most patients were 12 to 17 years of age, female, and White, with Medicaid being the predominant insurance. The most common chief complaint was suicidal ideation/plan/attempt. Self-referrals were the majority of assessments, and 59% of patients were already receiving mental health services. Median team response time was 19 minutes. There was an upward trend in consults. Psychiatric hospitalization was the most common disposition; more than 95% of the other visits had timely follow-up phone calls. CONCLUSION: Despite an increasing number of patients presenting to the ED with mental health crisis, safe and efficient management is possible with ED staff-social worker partnership. This approach can ensure that eligible patients receive consistent and evidence-based evaluations and can allow ED clinicians to respond to medical emergencies that require their attention.

Learning From a National Quality Improvement Collaborative for Brief Resolved Unexplained Events.

OBJECTIVE: In 2016, the American Academy of Pediatrics published the Brief Resolved Unexplained Event (BRUE) Clinical Practice Guideline (CPG). A multicenter quality improvement (QI) collaborative aimed to improve CPG adherence. METHODS: A QI collaborative of 15 hospitals aimed to improve testing adherence, the hospitalization of lower-risk infants, the correct use of diagnostic criteria, and risk classification. Interventions included CPG education, documentation practices, clinical pathways, and electronic medical record integration. By using medical record review, care of emergency department (ED) and inpatient patients meeting BRUE criteria was displayed via control or run charts for 3 time periods: pre-CPG publication (October 2015 to June 2016), post-CPG publication (July 2016 to September 2018), and collaborative (April 2019 to June 2020). Collaborative learning was used to identify and mitigate barriers to iterative improvement. RESULTS: A total of 1756 infants met BRUE criteria. After CPG publication, testing adherence improved from 56% to 64% and hospitalization decreased from 49% to 27% for lower-risk infants, but additional improvements were not demonstrated during the collaborative period. During the collaborative period, correct risk classification for hospitalized infants improved from 26% to 49% (ED) and 15% to 33% (inpatient) and the documentation of BRUE risk factors for hospitalized infants improved from 84% to 91% (ED). CONCLUSIONS: A national BRUE QI collaborative enhanced BRUE-related hospital outcomes and processes. Sites did not improve testing and hospitalization beyond the gains made after CPG publication, but they did shift the BRUE definition and risk classification. The incorporation of caregiver perspectives and the use of shared decision-making tools may further improve care.

Critical review on waste cooking oil rejuvenation in asphalt mixture with high recycled asphalt.

Waste cooking oil (WCO) as a rejuvenator is gaining attention in the pavement industry to incorporate higher reclaimed asphalt (RA) in asphalt mixture. This review article provides a comprehensive review on the current state and the feasibility of turning WCO and RA into cleaner and sustainable asphalt pavement material. Considering the advancements in research related to the utilization of WCO in RA mixture, it was necessary to critically review the past and recent studies to provide a methodological scope for future research. The review discusses a plethora of characteristics focusing on chemical, rheological, simulation, environmental, and economical findings related to the utilization of WCO in RA mixtures. Based on the review, WCO can be adjudged as a potential material to rejuvenate asphalt mixtures with higher recycled asphalt content. Furthermore, although WCO enhances low-to-intermediate temperature performance, studies indicated that moisture damage and higher temperature properties are compromised. Future research scope exists in understanding the rejuvenation capabilities of different WCOs and blends of different types of WCO, optimizing the transesterification process of WCO to improve its quality, molecular dynamic simulations focusing on transesterified WCO, quantification of environmental and economic benefits of recycled asphalt mixtures with WCO, and field performance studies.

Risk Prediction After a Brief Resolved Unexplained Event.

OBJECTIVES: Only 4% of brief resolved unexplained events (BRUE) are caused by a serious underlying illness. The American Academy of Pediatrics (AAP) guidelines do not distinguish patients who would benefit from further investigation and hospitalization. We aimed to derive and validate a clinical decision rule for predicting the risk of a serious underlying diagnosis or event recurrence. METHODS: We retrospectively identified infants presenting with a BRUE to 15 children's hospitals (2015-2020). We used logistic regression in a split-sample to derive and validate a risk prediction model. RESULTS: Of 3283 eligible patients, 565 (17.2%) had a serious underlying diagnosis (n = 150) or a recurrent event (n = 469). The AAP's higher-risk criteria were met in 91.5% (n = 3005) and predicted a serious diagnosis with 95.3% sensitivity, 8.6% specificity, and an area under the curve of 0.52 (95% confidence interval [CI]: 0.47-0.57). A derived model based on age, previous events, and abnormal medical history demonstrated an area under the curve of 0.64 (95%CI: 0.59-0.70). In contrast to the AAP criteria, patients >60 days were more likely to have a serious underlying diagnosis (odds ratio:1.43, 95%CI: 1.03-1.98, P = .03). CONCLUSIONS: Most infants presenting with a BRUE do not have a serious underlying pathology requiring prompt diagnosis. We derived 2 models to predict the risk of a serious diagnosis and event recurrence. A decision support tool based on this model may aid clinicians and caregivers in the discussion on the benefit of diagnostic testing and hospitalization (https://www.mdcalc.com/calc/10400/brief-resolved-unexplained-events-2.0-brue-2.0-criteria-infants).

Injury-Related Pediatric Emergency Department Visits in the First Year of COVID-19.

OBJECTIVES: To describe the epidemiology of pediatric injury-related visits to children's hospital emergency departments (EDs) in the United States during early and later periods of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. METHODS: We conducted a cross-sectional study using the Pediatric Health Information System, an administrative database to identify injury-related ED visits at 41 United States children's hospitals during the SARS-CoV-2 pandemic period (March 15, 2020 to March 14, 2021) and a 3 year comparator period (March 15-March 14, 2017-2020). For these 2 periods, we compared patient characteristics, injury type and severity, primary discharge diagnoses, and disposition, stratified by early (March 15, 2020 to June 30, 2020), middle (July 1, 2020 to October 31, 2020), and late (November 1, 2020 to March 14, 2021) pandemic periods. RESULTS: Overall, ED injury-related visits decreased by 26.6% during the first year of the SARS-CoV-2 pandemic, with the largest decline observed in minor injuries. ED injury-related visits resulting in serious-critical injuries increased across the pandemic (15.9% early, 4.9% middle, 20.6% late). Injury patterns with the sharpest relative declines included superficial injuries (41.7% early) and sprains/strains (62.4% early). Mechanisms of injury with the greatest relative increases included (1) firearms (22.9% early; 42.8% middle; 37% late), (2) pedal cyclists (60.4%; 24.9%; 32.2%), (3) other transportation (20.8%; 25.3%; 17.9%), and (4) suffocation/asphyxiation (21.4%; 20.2%; 28.4%) and injuries because of suicide intent (-16.2%, 19.9%, 21.8%). CONCLUSIONS: Pediatric injury-related ED visits declined in general. However, there was a relative increase in injuries with the highest severity, which warrants further investigation.

Optimizing Critical Care Documentation in a Pediatric Emergency Department.

OBJECTIVE: Emergency department (ED) physicians frequently provide critical care (CC) but document inconsistently. Variability in documentation can result in underbilling and is inconsistent with financial stewardship. We used admissions to the intensive care unit (ICU) as a proxy for CC provision. At baseline, CC notes were correctly documented for 20% of eligible visits, with potential missed charges of $1.8 million per year.Our objective was to increase CC note placement for eligible patients from 20% to 60% over 2 years. Additionally, we measured CC notes and the number of ICU admissions per 1000 ED visits, and change in facility fees. METHODS: We performed this project at a midwestern quaternary children's hospital with 2 EDs (combined volume 120,000 visits/year). We surveyed the ED physicians to inform our interventions. We used maintenance of certification points and financial incentives for quality improvement work to obtain buy-in. We used serial interventions with plan-do-study-act cycles: (1) CC note simplification, (2) education, (3) follow-up surveys, (4) additional location for CC note, and (5) timely reminders. We reviewed sample charts and used χ2 test and control charts for analysis. RESULTS: Critical care note placement for ICU admissions increased from 20% to 60% in 8 months, and further to greater than 75%. The CC notes increased from 4 to 16 per 1000 ED visits. Intensive care unit admissions increased but remained appropriate. The billed facility fee for CC increased by 263%. CONCLUSIONS: This project resulted in significant and sustained improvements in CC note completion. We believe providing education, simplifying the documentation process, automating reminders, and incentivizing optimal documentation were vital to success.

Behavioral presentations of focal onset seizures: A case series.

Seizures can have varied presentations and may have different etiological factors. A multidisciplinary approach should be used to treat them. It becomes difficult to diagnose seizures if they have an atypical presentation, particularly so when they manifest as behavioral disturbances. This case series demonstrates four cases with different psychiatric and behavioral manifestations of seizures where the diagnosis had to be done in a multi-disciplinary approach. Two of the cases highlight the fact that in the light of normal investigations, paying attention to detailed history is of prime importance.

Initiative to Increase the Rate of Emergency Department Physician Preprocedure Time-out Documentation.

The preprocedure time-out is an important safety measure to verify patient identity and accuracy of a planned procedure. The time-out is an institutional and Joint Commission requirement. However, physicians in our emergency departments (EDs) document it inconsistently. We aimed to improve physician preprocedure time-out documentation for deep sedation (ketamine and/or propofol) from 75% to 90%, and separately for cutaneous abscess incision and drainage (I&D) from 94% to 98% by June 2020. METHODS: We analyzed 1 year of baseline data and weekly electronic medical record (EMR) reports from November 2019 through June 2020. Our outcome measures were the rate of physician time-out documentation for deep sedation and I&D, respectively; our process measure was physician engagement. Our interventions included education, monthly reminders and updates, individualized feedback for insufficient documentation, EMR deep sedation, and I&D procedure note optimization, and academic and financial incentives. We used statistical process control chart quality improvement rules for discerning special versus common cause variation. RESULTS: Physician documentation of a preprocedure time-out improved from 75% to 100% for deep sedation and from 94% to 99.3% for I&D. These improvements remained sustained. All physicians were eligible for the financial bonus, and 40 (63%) met Maintenance of Certification credit requirements. CONCLUSIONS: Using quality improvement methodology, we increased physician time-out documentation for deep sedation and I&D through education, feedback, and systems enhancement. We improved Joint Commission regulatory compliance and reduced potential harm through these safety checks. Future studies may quantify patient safety effects and examine the efficacy of similar interventions for other procedures.

Risk Factors and Outcomes After a Brief Resolved Unexplained Event: A Multicenter Study.

BACKGROUND: The accuracy of the risk criteria for brief resolved unexplained events (BRUEs) from the American Academy of Pediatrics (AAP) is unknown. We sought to evaluate if AAP risk criteria and event characteristics predict BRUE outcomes. METHODS: This retrospective cohort included infants <1 year of age evaluated in the emergency departments (EDs) of 15 pediatric and community hospitals for a BRUE between October 1, 2015, and September 30, 2018. A multivariable regression model was used to evaluate the association of AAP risk factors and event characteristics with risk for event recurrence, revisits, and serious diagnoses explaining the BRUE. RESULTS: Of 2036 patients presenting with a BRUE, 87% had at least 1 AAP higher-risk factor. Revisits occurred in 6.9% of ED and 10.7% of hospital discharges. A serious diagnosis was made in 4.0% (82) of cases; 45% (37) of these diagnoses were identified after the index visit. The most common serious diagnoses included seizures (1.1% [23]) and airway abnormalities (0.64% [13]). Risk is increased for a serious underlying diagnosis for patients discharged from the ED with a history of a similar event, an event duration >1 minute, an abnormal medical history, and an altered responsiveness (P < .05). AAP risk criteria for all outcomes had a negative predictive value of 90% and a positive predictive value of 23%. CONCLUSIONS: AAP BRUE risk criteria are used to accurately identify patients at low risk for event recurrence, readmission, and a serious underlying diagnosis; however, their use results in the inaccurate identification of many patients as higher risk. This is likely because many AAP risk factors, such as age, are not associated with these outcomes.

Pediatric Emergency Department Challenges and Response to COVID-19.

Severe acute respiratory syndrome coronavirus 2, the virus causing the pandemic illness coronavirus disease 2019, was first detected in the United States in January 2020. As the illness spread across the country, all aspects and venues of health care were significantly impacted. This article explores the challenges and response of one children's emergency medicine division related to surge planning, personal protective equipment, screening, testing, staffing, and other operational challenges, and describes the impact and implications thus far. [Pediatr Ann. 2021;50(4):e172-e177.].

Pediatric Emergency Department Visits at US Children's Hospitals During the COVID-19 Pandemic.

BACKGROUND AND OBJECTIVES: The impact of the coronavirus disease 2019 (COVID-19) pandemic on pediatric emergency department (ED) visits is not well characterized. We aimed to describe the epidemiology of pediatric ED visits and resource use during the pandemic. METHODS: We conducted a cross-sectional study using the Pediatric Health Information System for ED visits to 27 US children's hospitals during the COVID-19 pandemic period (March 15, 2020, to August 31, 2020) and a 3-year comparator period (March 15 to August 31, 2017-2019). ED visit rates, patient and visit characteristics, resource use, and ED charges were compared between the time periods. We specifically evaluated changes in low-resource-intensity visits, defined as ED visits that did not result in hospitalization or medication administration and for which no laboratory tests, diagnostic imaging, or procedures were performed. RESULTS: ED visit rates decreased by 45.7% (average 911 026 ED visits over 2017-2019 vs 495 052 visits in 2020) during the pandemic. The largest decrease occurred among visits for respiratory disorders (70.0%). The pandemic was associated with a relative increase in the proportion of visits for children with a chronic condition from 23.7% to 27.8% (P < .001). The proportion of low-resource-intensity visits decreased by 7.0 percentage points, and total charges decreased by 20.0% during the pandemic period. CONCLUSIONS: The COVID-19 pandemic was associated with a marked decrease in pediatric ED visits across a broad range of conditions; however, the proportional decline of poisoning and mental health visits was less pronounced. The impact of decreased visits on patient outcomes warrants further research.

Selective Stabilization of Aspartic Acid Protonation State within a Given Protein Conformation Occurs via Specific "Molecular Association".

Proteins involved in proton-/electron-transfer processes often possess "functional" aspartates/aspartic acids (Asp) with variable protonation states. The mechanism of Asp protonation-deprotonation within proteins is unclear. Two questions were asked-the possible types of determinants responsible for Asp protonation-deprotonation and the spatial arrangements of the determinants leading to selective stabilization. The questions were analyzed using nine different solvent models, which scanned the complete protein dielectric range, and four protein models, which illustrated the spatial arrangements around Asp, termed as "molecular association". The methods employed were quantum chemical calculations and constant pH simulations. The types of the determinants identified were charge-charge interaction, H bonding, dipole-π interaction, extended electronic conjugation, dielectric effect, and solvent accessibility. All solvent-exposed Asp [buried fraction (BF) less than 0.5] were aspartates, and buried Asp were either aspartic acids or aspartates, each having a different "molecular association". The exposed aspartates were stabilized via a H-bonding network with bulk water, buried aspartates via salt bridge or, minimum, two intramolecular H bonds, and buried aspartic acids via, minimum, one intramolecular H bond. An "acid-alcohol pair" (involving Ser/Thr/Tyr) was a common determinant to any "functional" buried aspartate/aspartic acid. Higher energy "molecular associations" observed within proteins compared to those within water, presumably, indicated easy molecular restructuring and alteration of the Asp protonation states during a protein-mediated proton/electron transfer.

BOLD activation during cue induced craving in adolescent inhalant users.

Inhalants are legally available substances, most of them inexpensive, which are often abused by adolescents. Craving causes their continued use and repeated relapses. There is a need to understand the cue-induced craving and the associated neural mechanisms. In absence of any such prior study, the present study compared the hemodynamic changes in brain associated with craving effect in adolescent inhalant users and healthy controls using blood oxygen level dependent (BOLD) mechanism. This was an observational case control study with twelve adolescents, aged 12-18 years, with current use of inhalants as their primary drug, and twelve healthy, age and gender-matched adolescents, with no lifetime use of inhalants. Clinical assessments included Teen Addiction Severity Index and Visual Analogue Scale for craving. Participants abstained from all substances during 48 h prior to fMRI, confirmed by urinalysis. A validated visual cue block paradigm with neutral and craving cues was presented during the BOLD assessments in a 3 T MR system. The inhalant users exhibited BOLD activation in inferior frontal gyrus, inferior parietal lobule, superior occipital gyrus, cingulate gyrus, lentiform nucleus, thalamus, and culmen as compared to control group. The control group exhibited activation of insula as compared to cases. The results may be attributed to visuo-spatial attention, visual perception, working memory, and motivation associated with visual cue reactivity. This preliminary study provides important findings pertaining to activation patterns in response to cue-induced craving among adolescent inhalant users.

Large-scale survey and database of high affinity ligands for peptide recognition modules.

Many proteins involved in signal transduction contain peptide recognition modules (PRMs) that recognize short linear motifs (SLiMs) within their interaction partners. Here, we used large-scale peptide-phage display methods to derive optimal ligands for 163 unique PRMs representing 79 distinct structural families. We combined the new data with previous data that we collected for the large SH3, PDZ, and WW domain families to assemble a database containing 7,984 unique peptide ligands for 500 PRMs representing 82 structural families. For 74 PRMs, we acquired enough new data to map the specificity profiles in detail and derived position weight matrices and binding specificity logos based on multiple peptide ligands. These analyses showed that optimal peptide ligands resembled peptides observed in existing structures of PRM-ligand complexes, indicating that a large majority of the phage-derived peptides are likely to target natural peptide-binding sites and could thus act as inhibitors of natural protein-protein interactions. The complete dataset has been assembled in an online database (http://www.prm-db.org) that will enable many structural, functional, and biological studies of PRMs and SLiMs.

Reducing Streptococcal Testing in Patients <3 Years Old in an Emergency Department.

BACKGROUND: Although pharyngitis is common, group A Streptococcus is an uncommon etiology, and sequelae are rare in patients <3 years old. Inappropriate testing leads to increased cost of health care and unnecessary exposure to antibiotics. Rapid streptococcal tests (RSTs) for group A Streptococcus pharyngitis are not routinely indicated in this age group. At our urban, tertiary pediatric emergency department (ED), on average, 20 RSTs were performed each month for patients <3 years of age. Our objective was to reduce RSTs in the ED in patients aged <3 years by 50% in 18 months. METHODS: We initiated this project in October 2016 at an urban, tertiary pediatric ED. We surveyed pertinent multidisciplinary stakeholders to identify factors leading to RSTs in children <3 years of age. We conducted multiple interventions and collected weekly data on the number of RSTs in children aged <3 years (outcome measure) and the number of family complaints and return visits for complications of pharyngitis (balancing measure). We used statistical process control for analysis. RESULTS: The mean number of RSTs ordered per month in patients aged <3 years declined by 52% in 10 months. The majority of tests during the study phase were ordered by nurse practitioners (62%) for patients aged 25 to 36 months (66%). There has been 1 family grievance and no patient complications attributable to the project. CONCLUSIONS: Our interventions led to a successful and sustained reduction of RSTs in patients aged <3 years. A local clinical practice guideline was developed, and the project was expanded to other acute care settings.