scholarly journals Quantifying the Impact of Parametric Uncertainty on Automatic Mechanism Generation for CO2 Hydrogenation on Ni(111)

2021 ◽  
Author(s):  
Bjarne Kreitz ◽  
C. Franklin Goldsmith ◽  
Richard West ◽  
Emily Mazeau ◽  
Katrin Blondal ◽  
...  
Keyword(s):  
Rate Control ◽  
Parametric Uncertainty ◽  
Co2 Hydrogenation ◽  
Sensitivity Analyses ◽  
Control Analysis ◽  
Co2 Methanation ◽  
Model Predictions ◽  
Automatic Mechanism ◽  
Global Uncertainty ◽  
The Impact

Automatic mechanism generation is used to determine mechanisms for the CO2 hydrogenation on Ni(111) in a two-stage process, while considering the uncertainty in energetic parameters systematically. In a coarse stage, all the possible chemistry is explored with gas-phase products down to the ppb level, while a refined stage discovers the core methanation submechanism. 5,000 unique mechanisms were generated, which contain minor perturbations in all parameters. Global uncertainty assessment, global sensitivity analysis, and degree of rate control analysis are performed to study the effect 1 of this parametric uncertainty on the microkinetic model predictions. Comparison of the model predictions with experimental data on a Ni/SiO2 catalyst find a feasible set of microkinetic mechanisms that are in quantitative agreement with the measured data, without relying on explicit parameter optimization. Global uncertainty and sensitivity analyses provide tools to determine the pathways and key factors that control the methanation activity within the parameter space. Together, these methods reveal that the degree of rate control approach can be misleading if parametric uncertainty is not considered. The procedure of considering uncertainties in the automated mechanism generation is not unique to CO2 methanation and can be easily extended to other challenging heterogeneously catalyzed reactions<br>

scholarly journals Quantifying the Impact of Parametric Uncertainty on Automatic Mechanism Generation for CO2 Hydrogenation on Ni(111)

2021 ◽  
Author(s):  
Bjarne Kreitz ◽  
C. Franklin Goldsmith ◽  
Richard West ◽  
Emily Mazeau ◽  
Katrin Blondal ◽  
...  
Keyword(s):  
Rate Control ◽  
Parametric Uncertainty ◽  
Co2 Hydrogenation ◽  
Sensitivity Analyses ◽  
Control Analysis ◽  
Co2 Methanation ◽  
Model Predictions ◽  
Automatic Mechanism ◽  
Global Uncertainty ◽  
The Impact

Automatic mechanism generation is used to determine mechanisms for the CO2 hydrogenation on Ni(111) in a two-stage process, while considering the uncertainty in energetic parameters systematically. In a coarse stage, all the possible chemistry is explored with gas-phase products down to the ppb level, while a refined stage discovers the core methanation submechanism. 5,000 unique mechanisms were generated, which contain minor perturbations in all parameters. Global uncertainty assessment, global sensitivity analysis, and degree of rate control analysis are performed to study the effect 1 of this parametric uncertainty on the microkinetic model predictions. Comparison of the model predictions with experimental data on a Ni/SiO2 catalyst find a feasible set of microkinetic mechanisms that are in quantitative agreement with the measured data, without relying on explicit parameter optimization. Global uncertainty and sensitivity analyses provide tools to determine the pathways and key factors that control the methanation activity within the parameter space. Together, these methods reveal that the degree of rate control approach can be misleading if parametric uncertainty is not considered. The procedure of considering uncertainties in the automated mechanism generation is not unique to CO2 methanation and can be easily extended to other challenging heterogeneously catalyzed reactions<br>

scholarly journals Quantifying the Impact of Parametric Uncertainty on Automatic Mechanism Generation for CO2 Hydrogenation on Ni(111)

JACS Au ◽  
2021 ◽  
Author(s):  
Bjarne Kreitz ◽  
Khachik Sargsyan ◽  
Katrín Blöndal ◽  
Emily J. Mazeau ◽  
Richard H. West ◽  
...  
Keyword(s):  
Parametric Uncertainty ◽  
Co2 Hydrogenation ◽  
Automatic Mechanism ◽  
The Impact

scholarly journals Predicting the Impact of Typhoid Conjugate Vaccines on Antimicrobial Resistance

2019 ◽  
Vol 68 (Supplement_2) ◽  
pp. S96-S104 ◽  
Author(s):  
Samantha Kaufhold ◽  
Reza Yaesoubi ◽  
Virginia E Pitzer
Keyword(s):  
Vaccination Coverage ◽  
Selective Pressure ◽  
Sensitivity Analyses ◽  
Relative Fitness ◽  
Base Case ◽  
Model Parameters ◽  
Case Scenario ◽  
Conjugate Vaccines ◽  
Model Predictions ◽  
The Impact

Abstract Background Empiric prescribing of antimicrobials in typhoid-endemic settings has increased selective pressure on the development of antimicrobial-resistant Salmonella enterica serovar Typhi. The introduction of typhoid conjugate vaccines (TCVs) in these settings may relieve this selective pressure, thereby reducing resistant infections and improving health outcomes. Methods A deterministic transmission dynamic model was developed to simulate the impact of TCVs on the number and proportion of antimicrobial-resistant typhoid infections and chronic carriers. One-way sensitivity analyses were performed to ascertain particularly impactful model parameters influencing the proportion of antimicrobial-resistant infections and the proportion of cases averted over 10 years. Results The model simulations suggested that increasing vaccination coverage would decrease the total number of antimicrobial-resistant typhoid infections but not affect the proportion of cases that were antimicrobial resistant. In the base-case scenario with 80% vaccination coverage, 35% of all typhoid infections were antimicrobial resistant, and 44% of the total cases were averted over 10 years by vaccination. Vaccination also decreased both the total number and proportion of chronic carriers of antimicrobial-resistant infections. The prevalence of chronic carriers, recovery rates from infection, and relative fitness of resistant strains were identified as crucially important parameters. Conclusions Model predictions for the proportion of antimicrobial resistant infections and number of cases averted depended strongly on the relative fitness of the resistant strain(s), prevalence of chronic carriers, and rates of recovery without treatment. Further elucidation of these parameter values in real-world typhoid-endemic settings will improve model predictions and assist in targeting future vaccination campaigns and treatment strategies.

Effects of parametric uncertainty on multi-scale model predictions of shock response of a pressed energetic material

2019 ◽  
Vol 125 (23) ◽  
pp. 235104 ◽  
Author(s):  
Sangyup Lee ◽  
Oishik Sen ◽  
Nirmal Kumar Rai ◽  
Nicholas J. Gaul ◽  
K. K. Choi ◽  
...  
Keyword(s):  
Energetic Material ◽  
Parametric Uncertainty ◽  
Scale Model ◽  
Multi Scale ◽  
Model Predictions ◽  
Shock Response

Body mass index and risk of all-cause mortality in normotensive and hypertensive adults: The Rural Chinese Cohort Study

2021 ◽  
pp. 1-25
Author(s):  
Qionggui Zhou ◽  
Xuejiao Liu ◽  
Yang Zhao ◽  
Pei Qin ◽  
Yongcheng Ren ◽  
...  
Keyword(s):  
Cohort Study ◽  
Population Based ◽  
Normal Weight ◽  
Sensitivity Analyses ◽  
Hypertension Status ◽  
Moderation Effect ◽  
Increased Risk ◽  
All Cause Mortality ◽  
Chinese Cohort ◽  
The Impact

Abstract Objective: The impact of baseline hypertension status on the BMI–mortality association is still unclear. We aimed to examine the moderation effect of hypertension on the BMI–mortality association using a rural Chinese cohort. Design: In this cohort study, we investigated the incident of mortality according to different BMI categories by hypertension status. Setting: Longitudinal population-based cohort Participants: 17,262 adults ≥18 years were recruited from July to August of 2013 and July to August of 2014 from a rural area in China. Results: During a median 6-year follow-up, we recorded 1109 deaths (610 with and 499 without hypertension). In adjusted models, as compared with BMI 22-24 kg/m2, with BMI ≤18, 18-20, 20-22, 24-26, 26-28, 28-30 and >30 kg/m2, the HRs (95% CI) for mortality in normotensive participants were 1.92 (1.23-3.00), 1.44 (1.01-2.05), 1.14 (0.82-1.58), 0.96 (0.70-1.31), 0.96 (0.65-1.43), 1.32 (0.81-2.14), and 1.32 (0.74-2.35) respectively, and in hypertensive participants were 1.85 (1.08-3.17), 1.67 (1.17-2.39), 1.29 (0.95-1.75), 1.20 (0.91-1.58), 1.10 (0.83-1.46), 1.10 (0.80-1.52), and 0.61 (0.40-0.94) respectively. The risk of mortality was lower in individuals with hypertension with overweight or obesity versus normal weight, especially in older hypertensives (≥60 years old). Sensitivity analyses gave consistent results for both normotensive and hypertensive participants. Conclusions: Low BMI was significantly associated with increased risk of all-cause mortality regardless of hypertension status in rural Chinese adults, but high BMI decreased the mortality risk among individuals with hypertension, especially in older hypertensives.

scholarly journals Impact of public health interventions to curb SARS-CoV-2 spread assessed by an evidence-educated Delphi panel and tailored SEIR model

2021 ◽  
Author(s):  
Bernd Brüggenjürgen ◽  
Hans-Peter Stricker ◽  
Lilian Krist ◽  
Miriam Ortiz ◽  
Thomas Reinhold ◽  
...  
Keyword(s):  
Public Health ◽  
Transmission Rate ◽  
Latency Period ◽  
Policy Decision ◽  
Sensitivity Analyses ◽  
Delphi Panel ◽  
Time Step ◽  
Seir Model ◽  
Health Policy Decision ◽  
The Impact

Abstract Aim To use a Delphi-panel-based assessment of the effectiveness of different non-pharmaceutical interventions (NPI) in order to retrospectively approximate and to prospectively predict the SARS-CoV-2 pandemic progression via a SEIR model (susceptible, exposed, infectious, removed). Methods We applied an evidence-educated Delphi-panel approach to elicit the impact of NPIs on the SARS-CoV-2 transmission rate R0 in Germany. Effectiveness was defined as the product of efficacy and compliance. A discrete, deterministic SEIR model with time step of 1 day, a latency period of 1.8 days, duration of infectiousness of 5 days, and a share of the total population of 15% assumed to be protected by immunity was developed in order to estimate the impact of selected NPI measures on the course of the pandemic. The model was populated with the Delphi-panel results and varied in sensitivity analyses. Results Efficacy and compliance estimates for the three most effective NPIs were as follows: test and isolate 49% (efficacy)/78% (compliance), keeping distance 42%/74%, personal protection masks (cloth masks or other face masks) 33%/79%. Applying all NPI effectiveness estimates to the SEIR model resulted in a valid replication of reported occurrence of the German SARS-CoV-2 pandemic. A combination of four NPIs at consented compliance rates might curb the CoViD-19 pandemic. Conclusion Employing an evidence-educated Delphi-panel approach can support SARS-CoV-2 modelling. Future curbing scenarios require a combination of NPIs. A Delphi-panel-based NPI assessment and modelling might support public health policy decision making by informing sequence and number of needed public health measures.

scholarly journals Online art therapy in elementary schools during COVID-19: results from a randomized cluster pilot and feasibility study and impact on mental health

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Catherine Malboeuf-Hurtubise ◽  
Terra Léger-Goodes ◽  
Geneviève A. Mageau ◽  
Geneviève Taylor ◽  
Catherine M. Herba ◽  
...  
Keyword(s):  
Mental Health ◽  
Elementary School ◽  
Art Therapy ◽  
Feasibility Study ◽  
School Children ◽  
Elementary School Children ◽  
Children’S Mental Health ◽  
Children's Mental Health ◽  
Sensitivity Analyses ◽  
The Impact

Abstract Background Emerging literature on the current COVID-19 crisis suggests that children may experience increased anxiety and depression as a result of the pandemic. To prevent such school and mental health-related problems, there is a timely need to develop preventive strategies and interventions to address potential negative impacts of COVID-19 on children’s mental health, especially in school settings. Results from previous child clinical research indicate that art-based therapies, including mindfulness-based art therapy, have shown promise to increase children’s well-being and reduce psychological distress. Objective The goal of the present pilot and feasibility study was to compare the impact of an emotion-based directed drawing intervention and a mandala drawing intervention, on mental health in elementary school children (N = 22), in the context of the COVID-19 pandemic. Both interventions were group-based and delivered online and remotely. A pilot study using a randomized cluster design was implemented to evaluate and compare both interventions in relation to child anxiety, depression, inattention and hyperactivity symptoms. Results Analyses of covariance revealed a significant effect of the type of drawing intervention on levels of inattention, after controlling for baseline levels. Participants in the emotion-based directed drawing group showed lower inattention scores at post-test, when compared to participants in the mandala group. Post-hoc sensitivity analyses showed significant decreases in pre-to-post scores for levels of hyperactivity for the complete sample. Conclusion Overall, results from this pilot and feasibility study showed that both an emotion-based directed drawing intervention and a mandala drawing intervention may be beneficial to improve mental health in elementary school children, in the context of the current COVID-19 pandemic. From a feasibility standpoint, results indicate that the implementation of both interventions online and remotely, through a videoconference platform, is feasible and adequate in school-based settings. Further work incorporating larger sample sizes, longitudinal data and ensuring sufficient statistical power is warranted to evaluate the long-term impact of both interventions on children’s mental health.

Gastrostomy Tubes Placed in Children With Neurologic Impairment: Associated Morbidity and Mortality

2021 ◽  
pp. 088307382110001
Author(s):  
Jody L. Lin ◽  
Joseph Rigdon ◽  
Keith Van Haren ◽  
MyMy Buu ◽  
Olga Saynina ◽  
...  
Keyword(s):  
Severe Pneumonia ◽  
Sensitivity Analyses ◽  
Tube Placement ◽  
Composite Outcome ◽  
Eligibility Criteria ◽  
Risk Of Death ◽  
Cox Proportional Hazard ◽  
Neurologic Impairment ◽  
Increased Risk ◽  
The Impact

Background: Gastrostomy tube (G-tube) placement for children with neurologic impairment with dysphagia has been suggested for pneumonia prevention. However, prior studies demonstrated an association between G-tube placement and increased risk of pneumonia. We evaluate the association between timing of G-tube placement and death or severe pneumonia in children with neurologic impairment. Methods: We included all children enrolled in California Children’s Services between July 1, 2009, and June 30, 2014, with neurologic impairment and 1 pneumonia hospitalization. Prior to analysis, children with new G-tubes and those without were 1:2 propensity score matched on sociodemographics, medical complexity, and severity of index hospitalization. We used a time-varying Cox proportional hazard model for subsequent death or composite outcome of death or severe pneumonia to compare those with new G-tubes vs those without, adjusting for covariates described above. Results: A total of 2490 children met eligibility criteria, of whom 219 (9%) died and 789 (32%) had severe pneumonia. Compared to children without G-tubes, children with new G-tubes had decreased risk of death (hazard ratio [HR] 0.47, 95% confidence interval [CI] 0.39-0.55) but increased risk of the composite outcome (HR 1.21, CI 1.14-1.27). Sensitivity analyses using varied time criteria for definitions of G-tube and outcome found that more recent G-tube placement had greater associated risk reduction for death but increased risk of severe pneumonia. Conclusion: Recent G-tube placement is associated with reduced risk of death but increased risk of severe pneumonia. Decisions to place G-tubes for pulmonary indications in children with neurologic impairment should weigh the impact of severe pneumonia on quality of life.

scholarly journals The impact of teaching on the duration of common urological operations

2016 ◽  
Vol 10 (5-6) ◽  
pp. 172 ◽  
Author(s):  
Blayne Welk ◽  
Jennifer Winick-Ng ◽  
Andrew McClure ◽  
Chris Vinden ◽  
Sumit Dave ◽  
...  
Keyword(s):  
Radical Prostatectomy ◽  
Negative Binomial ◽  
Negative Binomial Regression ◽  
Potential Effect ◽  
Sensitivity Analyses ◽  
Teaching Hospitals ◽  
Operative Duration ◽  
Open Radical Prostatectomy ◽  
Academic Hospitals ◽  
The Impact

Introduction: The ability of academic (teaching) hospitals to offer the same level of efficiency as non-teaching hospitals in a publicly funded healthcare system is unknown. Our objective was to compare the operative duration of general urology procedures between teaching and non-teaching hospitals. Methods: We used administrative data from the province of Ontario to conduct a retrospective cohort study of all adults who underwent a specified elective urology procedure (2002–2013). Primary outcome was duration of surgical procedure. Primary exposure was hospital type (academic or non-teaching). Negative binomial regression was used to adjust relative time estimates for age, comorbidity, obesity, anesthetic, and surgeon and hospital case volume.Results: 114 225 procedures were included (circumcision n=12 280; hydrocelectomy n=7221; open radical prostatectomy n=22 951; transurethral prostatectomy n=56 066; or mid-urethral sling n=15 707). These procedures were performed in an academic hospital in 14.8%, 13.3%, 28.6%, 17.1%, and 21.3% of cases, respectively. The mean operative duration across all procedures was higher in academic centres; the additional operative time ranged from 8.3 minutes (circumcision) to 29.2 minutes (radical prostatectomy). In adjusted analysis, patients treated in academic hospitals were still found to have procedures that were significantly longer (by 10‒21%). These results were similar in sensitivity analyses that accounted for the potential effect of more complex patients being referred to tertiary academic centres.Conclusions: Five common general urology operations take significantly longer to perform in academic hospitals. The reason for this may be due to the combined effect of teaching students and residents or due to inherent systematic inefficiencies within large academic hospitals.

scholarly journals Survival in elderly glioblastoma patients treated with bevacizumab-based regimens in the United States

2018 ◽  
Vol 5 (4) ◽  
pp. 251-261 ◽  
Author(s):  
Jessica Davies ◽  
Irmarie Reyes-Rivera ◽  
Thirupathi Pattipaka ◽  
Stephen Skirboll ◽  
Beatrice Ugiliweneza ◽  
...  
Keyword(s):  
Elderly Patients ◽  
Lower Risk ◽  
Karnofsky Performance Status ◽  
The United States ◽  
Cox Proportional Hazards Model ◽  
Sensitivity Analyses ◽  
Primary Analysis ◽  
Risk Of Death ◽  
Initial Surgery ◽  
The Impact

AbstractBackgroundThe efficacy of bevacizumab (BEV) in elderly patients with glioblastoma remains unclear. We evaluated the effect of BEV on survival in this patient population using the Survival, Epidemiology, and End Results (SEER)-Medicare database.MethodsThis retrospective, cohort study analyzed SEER-Medicare data for patients (aged ≥66 years) diagnosed with glioblastoma from 2006 to 2011. Two cohorts were constructed: one comprised patients who had received BEV (BEV cohort); the other comprised patients who had received any anticancer treatment other than BEV (NBEV cohort). The primary analysis used a multivariate Cox proportional hazards model to compare overall survival in the BEV and NBEV cohorts with initiation of BEV as a time-dependent variable, adjusting for potential confounders (age, gender, Charlson comorbidity index, region, race, radiotherapy after initial surgery, and diagnosis of coronary artery disease). Sensitivity analyses were conducted using landmark survival, propensity score modeling, and the impact of poor Karnofsky Performance Status.ResultsWe identified 2603 patients (BEV, n = 597; NBEV, n = 2006). In the BEV cohort, most patients were Caucasian males and were younger with fewer comorbidities and more initial resections. In the primary analysis, the BEV cohort showed a lower risk of death compared with the NBEV cohort (hazard ratio, 0.80; 95% confidence interval, 0.72–0.89; P < .01). The survival benefit of BEV appeared independent of the number of temozolomide cycles or frontline treatment with radiotherapy and temozolomide.ConclusionBEV exposure was associated with a lower risk of death, providing evidence that there might be a potential benefit of BEV in elderly patients with glioblastoma.

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