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An investigation of shock diffraction through a non-quiescent background medium is presented using both experimental and numerical techniques. Unlike diffracting shocks in quiescent media, a spatial distortion of the shock front occurs, producing a region of constant shock angle. An example of this process arises in the exhaust from a pulse-detonation combustor. As the background velocity is increased, such as through the inclusion of a converging nozzle at the exhaust, the spatial distortion becomes more apparent. Numerical simulations using a compressible Euler solver demonstrate that the distortion is not due to the geometrical influence of the nozzle, but rather is a function of the magnitude of the background flow velocity. The distortion is studied using a modified geometrical shock dynamics formulation which includes the background flow and is validated against experiments. A simple model is presented to predict the shock distortion angle in the weak-shock limit. Finally, the axial decay behaviour of the shock is investigated and it is shown that the advection of the shock by the background flow delays the arrival of the head and tail of the expansion characteristic at the centreline. This leads to an increase in the rate of decay of the shock Mach number as the background flow velocity is increased.
Land-use changes and forest management decisions can profoundly alter soil organic carbon (SOC) stocks. Therefore, the objective of this study was to investigate whether existing SOC stocks in the forests of Singapore can be related to successional stages of forest vegetation following disturbances. A forest classification system was developed using information about land use history and vegetation data from 21 inventory plots collected within the framework of Singapore’s IPCC-compatible greenhouse gas reporting system. The forest successional classes obtained were related to SOC stocks (0–50 cm) determined on the same plots. The inventory plots were assigned to four classes. Primary forests (Class 1) were dominated by late succession native species. Secondary forests representing natural forest succession (Class 2) contained younger native trees and a few large trees. Secondary forests after tree plantation/fruit orchard (Class 3) and after agricultural crop cultivation (Class 4) were characterised by large proportions of exotic tree species. Maximum stocks of SOC declined from Class 1 (127.7 Mg ha−1) to Class 4 (35.2 Mg ha−1). The results of a principal component analysis confirmed our forest classification. Plant-related parameters can be successfully used to classify the forests in Singapore, which also show clear differences in SOC.
Inpatient surgical site infections (SSIs) cause morbidity in children. The SSI rate among pediatric ambulatory surgery patients is less clear. To fill this gap, we conducted a multiple-institution, retrospective epidemiologic study to identify incidence, risk factors, and outcomes.
Methods:
We identified patients aged <22 years with ambulatory visits between October 2010 and September 2015 via electronic queries at 3 medical centers. We performed sample chart reviews to confirm ambulatory surgery and adjudicate SSIs. Weighted Poisson incidence rates were calculated. Separately, we used case–control methodology using multivariate backward logistical regression to assess risk-factor association with SSI.
Results:
In total, 65,056 patients were identified by queries, and we performed complete chart reviews for 13,795 patients; we identified 45 SSIs following ambulatory surgery. The weighted SSI incidence following pediatric ambulatory surgery was 2.00 SSI per 1,000 ambulatory surgeries (95% confidence interval [CI], 1.37–3.00). Integumentary surgeries had the highest weighted SSI incidence, 3.24 per 1,000 ambulatory surgeries (95% CI, 0.32–12). The following variables carried significantly increased odds of infection: clean contaminated or contaminated wound class compared to clean (odds ratio [OR], 9.8; 95% CI, 2.0–48), other insurance type compared to private (OR, 4.0; 95% CI, 1.6–9.8), and surgery on weekend day compared to weekday (OR, 30; 95% CI, 2.9–315). Of the 45 instances of SSI following pediatric ambulatory surgery, 40% of patients were admitted to the hospital and 36% required a new operative procedure or bedside incision and drainage.
Conclusions:
Our findings suggest that morbidity is associated with SSI following ambulatory surgery in children, and we also identified possible targets for intervention.
Health disparities between Appalachia and the rest of the country are widening. To address this, the Appalachian Translational Research Network (ATRN) organizes an annual ATRN Health Summit. The most recent Summit was held online September 22–23, 2020, and hosted by Wake Forest Clinical and Translational Science Institute in partnership with the Northwest Area Health Education Center. The Summit, titled “Community-Engaged Research in Translational Science: Innovations to Improve Health in Appalachia,” brought together a diverse group of 141 stakeholders from communities, academic institutions, and the National Center for Advancing Translational Science (NCATS) to highlight current research, identify innovative approaches to translational science and community-engaged research, develop cross-regional research partnerships, and establish and disseminate priorities for future Appalachian-focused research. The Summit included three plenary presentations and 39 presentations within 12 concurrent breakout sessions. Here, we describe the Summit planning process and implementation, highlight some of the research presented, and outline nine emergent themes to guide future Appalachian-focused research.
Background:
Rapidly identifying patients colonized with multidrug-resistant organisms (MDROs) upon ICU admission is critical to control and prevent the spread of these pathogens in healthcare facilities. Electronic health records (EHR) provide a rich source of data to predict the likelihood of MDRO colonization at admission, whereas surveillance methods are resource intensive and results are not immediately available. Our objectives were (1) to predict VRE and CRO colonization at ICU admission and (2) to identify patient subpopulations at higher risk for colonization with these MDROs. Methods: We conducted a retrospective analysis of patients aged ≥16 years admitted to any of 6 medical or surgical intensive care units (ICU) in the Johns Hopkins Hospital from July 1, 2016, through June 30, 2018. Perirectal swabs were collected at ICU unit admission and were tested for VRE and CRO. Patient demographic data, prior hospitalizations, and preadmission clinical data, including prior medication administration, prior diagnoses, and prior procedures, were extracted to develop prediction models. We employed the machine-learning algorithms logistic regression (LR), random forest (RF), and XGBoost (XG). The sum of sensitivity and specificity (ie, Youden’s index) was selected as the performance metric. Results: In total, 5,033 separate ICU visits from 3,385 patients were included, where 555 (11%) and 373 (7%) admissions tested positive for VRE and CRO, respectively. The sensitivity and specificity of our models for VRE were 78% and 80% with LR, 80% and 82% with RF, and 77% and 87% with XG. Predictions for CRO were not as precise, with LR at 73% and 53%, RF at 81% and 48%, and XG at 69% and 61%. The XG algorithm was the best-performing algorithm for both VRE and CRO. Prior VRE colonization, recent (<180 days) long-term care facility stay, and prior hospitalization >60 days were the key predictors for VRE, whereas the primary predictor for CRO colonization was prior carbapenem use. Conclusions: We demonstrated that EHR data can be used to predict >75% of VRE positive cases with a <15% false-positive rate and ~70% of CRO cases with a <40% false-positive rate. Future studies using larger sample sizes may improve the prediction accuracy and inform model generalizability across sites and thus reduce the risk of transmission of MDROs by rapidly identifying MDRO-colonized patients.
Funding: This work was funded by the Centers for Disease Control and Prevention (CDC) Epicenters Program (Grant Number 1U54CK000447) and the CDC MInD-Healthcare Program (Grant Number 1U01CK000536).
Health system preparedness for coronavirus disease (COVID-19) includes projecting the number and timing of cases requiring various types of treatment. Several tools were developed to assist in this planning process. This review highlights models that project both caseload and hospital capacity requirements over time.
Methods:
We systematically reviewed the medical and engineering literature according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We completed searches using PubMed, EMBASE, ISI Web of Science, Google Scholar, and the Google search engine.
Results:
The search strategy identified 690 articles. For a detailed review, we selected 6 models that met our predefined criteria. Half of the models did not include age-stratified parameters, and only 1 included the option to represent a second wave. Hospital patient flow was simplified in all models; however, some considered more complex patient pathways. One model included fatality ratios with length of stay (LOS) adjustments for survivors versus those who die, and accommodated different LOS for critical care patients with or without a ventilator.
Conclusion:
The results of our study provide information to physicians, hospital administrators, emergency response personnel, and governmental agencies on available models for preparing scenario-based plans for responding to the COVID-19 or similar type of outbreak.
Ambulatory healthcare-associated infections (HAIs) occur frequently in children and are associated with morbidity. Less is known about ambulatory HAI costs. This study estimated additional costs associated with pediatric ambulatory central-line–associated bloodstream infections (CLABSIs), catheter-associated urinary tract infections (CAUTI), and surgical site infections (SSIs) following ambulatory surgery.
Design:
Retrospective case-control study.
Setting:
Four academic medical centers.
Patients:
Children aged 0–22 years seen between 2010 and 2015 and at risk for HAI as identified by electronic queries.
Methods:
Chart review adjudicated HAIs. Charges were obtained for patients with HAIs and matched controls 30 days before HAI, on the day of, and 30 days after HAI. Charges were converted to costs and 2015 USD. Mixed-effects linear regression was used to estimate the difference-in-differences of HAI case versus control costs in 2 models: unrecorded charge values considered missing and a sensitivity analysis with unrecorded charge considered $0.
Results:
Our search identified 177 patients with ambulatory CLABSIs, 53 with ambulatory CAUTIs, and 26 with SSIs following ambulatory surgery who were matched with 382, 110, and 75 controls, respectively. Additional cost associated with an ambulatory CLABSI was $5,684 (95% confidence interval [CI], $1,005–$10,362) and $6,502 (95% CI, $2,261–$10,744) in the 2 models; cost associated with a CAUTI was $6,660 (95% CI, $1,055, $12,145) and $2,661 (95% CI, −$431 to $5,753); cost associated with an SSI following ambulatory surgery at 1 institution only was $6,370 (95% CI, $4,022–$8,719).
Conclusions:
Ambulatory HAI in pediatric patients are associated with significant additional costs. Further work is needed to reduce ambulatory HAIs.
Brain imaging studies have shown altered amygdala activity during emotion processing in children and adolescents with oppositional defiant disorder (ODD) and conduct disorder (CD) compared to typically developing children and adolescents (TD). Here we aimed to assess whether aggression-related subtypes (reactive and proactive aggression) and callous-unemotional (CU) traits predicted variation in amygdala activity and skin conductance (SC) response during emotion processing.
Methods
We included 177 participants (n = 108 cases with disruptive behaviour and/or ODD/CD and n = 69 TD), aged 8–18 years, across nine sites in Europe, as part of the EU Aggressotype and MATRICS projects. All participants performed an emotional face-matching functional magnetic resonance imaging task.
Results
Differences between cases and TD in affective processing, as well as specificity of activation patterns for aggression subtypes and CU traits, were assessed. Simultaneous SC recordings were acquired in a subsample (n = 63). Cases compared to TDs showed higher amygdala activity in response to negative faces (fearful and angry) v. shapes. Subtyping cases according to aggression-related subtypes did not significantly influence on amygdala activity; while stratification based on CU traits was more sensitive and revealed decreased amygdala activity in the high CU group. SC responses were significantly lower in cases and negatively correlated with CU traits, reactive and proactive aggression.
Conclusions
Our results showed differences in amygdala activity and SC responses to emotional faces between cases with ODD/CD and TD, while CU traits moderate both central (amygdala) and peripheral (SC) responses. Our insights regarding subtypes and trait-specific aggression could be used for improved diagnostics and personalized treatment.
Catheter-associated urinary tract infections (CAUTIs) occur frequently in pediatric inpatients, and they are associated with increased morbidity and cost. Few studies have investigated ambulatory CAUTIs, despite at-risk children utilizing home urinary catheterization. This retrospective cohort and case-control study determined incidence, risk factors, and outcomes of pediatric patients with ambulatory CAUTI.
Design:
Broad electronic queries identified potential patients with ambulatory urinary catheters, and direct chart review confirmed catheters and adjudicated whether ambulatory CAUTI occurred. CAUTI definitions included clean intermittent catheterization (CIC). Our matched case-control analysis assessed risk factors.
Setting:
Five urban, academic medical centers, part of the New York City Clinical Data Research Network.
Patients:
Potential patients were age <22 years who were seen between October 2010 and September 2015.
Results:
In total, 3,598 eligible patients were identified; 359 of these used ambulatory catheterization (representing186,616 ambulatory catheter days). Of these, 63 patients (18%) experienced 95 ambulatory CAUTIs. The overall ambulatory CAUTI incidence was 0.51 infections per 1,000 catheter days (1.35 for indwelling catheters and 0.47 for CIC; incidence rate ratio, 2.88). Patients with nonprivate medical insurance (odds ratio, 2.5; 95% confidence interval, 1.1–6.3) were significantly more likely to have ambulatory CAUTIs in bivariate models but not multivariable models. Also, 45% of ambulatory CAUTI resulted in hospitalization (median duration, 3 days); 5% resulted in intensive care admission; 47% underwent imaging; and 88% were treated with antibiotics.
Conclusions:
Pediatric ambulatory CAUTIs occur in 18% of patients with catheters; they are associated with morbidity and healthcare utilization. Ambulatory indwelling catheter CAUTI incidence exceeded national inpatient incidence. Future quality improvement research to reduce these harmful infections is warranted.
The computer aided internal optimisation (CAIO) method produces an optimised fibre layout for parts made from fibre-reinforced plastics (FRP), starting from an initial shell geometry and a given load case. Its main principle is iterative reduction of shear stresses by aligning fibre main axes with principal normal stress trajectories. Previous contributions, ranging from CAIO’s introduction over testing to extensions towards multi-layer FRP laminates, highlighted its lightweight design potential. For its application to laminate design approaches, alterations have been proposed; however, questions remain open. These questions include which convergence criteria to use, how to handle ambiguous principle normal stress trajectories, influence of using multi-layer CAIO optimisation instead of the initial single-layer CAIO and how dire consequences of slightly deviating fibre orientations from the optimised trajectories are. These challenges are discussed in depth and guidelines are given. This paper is an enhanced version of a distinguished contribution at the first symposium ‘Lightweight Design in Product Development’, Zurich (June 14–15, 2018).
Whenever Lutosławski speaks about his music, he exhibits a Freudian ambivalence of the variety that expresses one idea while being at pains to hide a conflicting one. As Freud explains, an ambivalent attitude involves the desire to perform an act that the subject considers consciously to be taboo while feels unconsciously to be enjoyable. In Lutosławski's case, he refuses to acknowledge any extra-musical content to his music, as if to do so would break the taboo of the absolute. Yet, his words about music belie an unconscious acknowledgement of its power of expression, drama and even narrative. As I have discussed elsewhere, this ambivalence is particularly evident in Tadeusz Kaczyński's published conversations with Lutosławski, especially in an outburst of dismay concerning Kaczyński's interpretation of the Cello Concerto.
I'm horrified to see how one can be carried away by my careless mention of the dramatic conflict between the solo part and the orchestra. I must immediately use the reins on this galloping imagination which prompts you to interpret the work as an illustration to some macabre spectacle.
Later in the same interview, Lutosławski maintains that he views ‘any discourse about the so-called content of a composition with some scepticism’, because to him ‘this content is absent’. Still, in an interview with Irina Nikolska, Lutosławski admits that the term ‘form’ is inadequate to describe his music because it lacks the ‘dramatic and literary implications’ that the Polish word akcja (action) or the English word ‘dramaturgy’ include. While at pains in his interview with Kaczyński to deny music's content, Lutosławski nevertheless lets slip that there are dramatic and literary implications in his music during his interview with Nikolska.
This ambivalence about music's content is also manifest in Kaczyński's interview with Lutosławski concerning the String Quartet of 1964. The composer affirms that his quartet had special significance in his oeuvre, although his reasoning relates to the impossibly fraught concept of the purely musical. Lutosławski mentions the two-movement form (‘the first one less important than the second’), the episodic opening, and the ‘advanced aleatory’, among other technical features, as important practices that he developed again in the Second Symphony and the Cello Concerto.
Very Long Baseline Interferometry (VLBI) at sub-millimeter waves has the potential to image the shadow of the black hole in the Galactic Center, Sagittarius A* (Sgr A*), and thereby test basic predictions of the theory of general relativity. We investigate the imaging prospects of a new Space VLBI mission concept. The setup consists of two satellites in polar or equatorial circular Medium-Earth Orbits with slightly different radii, resulting in a dense spiral-shaped uv-coverage with long baselines, allowing for extremely high-resolution and high-fidelity imaging of radio sources. We simulate observations of a general relativistic magnetohydrodynamics model of Sgr A* for this configuration with noise calculated from model system parameters. After gridding the uv-plane and averaging visibilities accumulated over multiple months of integration, images of Sgr A* with a resolution of up to 4 μ as could be reconstructed, allowing for stronger tests of general relativity and accretion models than with ground-based VLBI.
Expert knowledge of cardiac malformations is essential for paediatric cardiologists. Current cardiac morphology fellowship teaching format, content, and nomenclature are left up to the discretion of the individual fellowship programmes. We aimed to assess practices and barriers in morphology education, perceived effectiveness of current curricula, and preferences for a standardised fellow morphology curriculum.
Methods
A web-based survey was developed de novo and administered anonymously via e-mail to all paediatric cardiology fellowship programme directors and associate directors in the United States of America; leaders were asked to forward the survey to fellows.
Results
A total of 35 directors from 32 programmes (51%) and 66 fellows responded. Curriculum formats varied: 28 (88%) programmes utilised pathological specimens, 25 (78%) invited outside faculty, and 16 (50%) utilised external conferences. Director nomenclature preferences were split – 6 (19%) Andersonian, 8 (25%) Van Praaghian, and 18 (56%) mixed. Barriers to morphology education included time and inconsistent nomenclature. One-third of directors reported that <90% of recent fellow graduates had adequate abilities to apply segmental anatomy, identify associated cardiac lesions, or communicate complex CHD. More structured teaching, protected time, and specimens were suggestions to improve curricula. Almost 75% would likely adopt/utilise an online morphology curriculum.
Conclusions
Cardiac morphology training varies in content and format among fellowships. Inconsistent nomenclature exists, and inadequate morphology knowledge is perceived to contribute to communication failures, both have potential patient safety implications. There is an educational need for a common, online cardiac morphology curriculum that could allow for fellow assessment of competency and contribute to more standardised communication in the field of paediatric cardiology.
Childhood abuse and neglect (CAN) is considered as a risk factor for substance use disorder (SUD). Based on the drinking to cope model, this study investigated the association of two trauma-relevant emotions (shame and sadness) and substance use. Using ecological momentary assessment we compared real-time emotion regulation in situations with high and low intensity of shame and sadness in currently abstinent patients with CAN and lifetime SUD (traumaSUD group), healthy controls with CAN (traumaHC group), and without CAN (nontraumaHC group). Multilevel analysis showed a positive linear relationship between high intensity of both emotions and substance use for all groups. The traumaSUD group showed heightened substance use in low, as well as in high, intensity of shame and sadness. In addition, we found an interaction between type of emotion, intensity, and group: the traumaHC group exhibited a fourfold increased risk for substance use in high intense shame situations relative to the traumaSUD group. Our findings provide evidence for the drinking to cope model. The traumaSUD group showed a reduced distress tolerance for variable intensity of negative emotions. The differential effect of intense shame for the traumaHC group emphazises its potential role in the development of SUD following CAN. In addition, shame can be considered a relevant focus for therapeutic preinterventions and interventions for SUD after CAN.