The Coronavirus Disease 2019 (COVID-19) pandemic continues to have a devastating effect on the health and well-being of the global population. A critical step in the fight against COVID-19 is ...effective screening of infected patients, with one of the key screening approaches being radiology examination using chest radiography. It was found in early studies that patients present abnormalities in chest radiography images that are characteristic of those infected with COVID-19. Motivated by this and inspired by the open source efforts of the research community, in this study we introduce COVID-Net, a deep convolutional neural network design tailored for the detection of COVID-19 cases from chest X-ray (CXR) images that is open source and available to the general public. To the best of the authors' knowledge, COVID-Net is one of the first open source network designs for COVID-19 detection from CXR images at the time of initial release. We also introduce COVIDx, an open access benchmark dataset that we generated comprising of 13,975 CXR images across 13,870 patient patient cases, with the largest number of publicly available COVID-19 positive cases to the best of the authors' knowledge. Furthermore, we investigate how COVID-Net makes predictions using an explainability method in an attempt to not only gain deeper insights into critical factors associated with COVID cases, which can aid clinicians in improved screening, but also audit COVID-Net in a responsible and transparent manner to validate that it is making decisions based on relevant information from the CXR images. By no means a production-ready solution, the hope is that the open access COVID-Net, along with the description on constructing the open source COVIDx dataset, will be leveraged and build upon by both researchers and citizen data scientists alike to accelerate the development of highly accurate yet practical deep learning solutions for detecting COVID-19 cases and accelerate treatment of those who need it the most.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
About five billion tons of plastic waste have accumulated in landfills and the natural environment over the past 50 years. Polypropylene (PP) waste accounts for about 23% of the total plastic waste. ...Converting PP waste into useful products can reduce the accumulated waste and associated risks to the environment and human health. In this study, model PP was converted into oil using supercritical water at 380–500 °C and 23 MPa over a reaction time of 0.5–6 h. Up to 91 wt % of model PP was converted into oil at 425 °C with a 2–4 h reaction time or at 450 °C with a 0.5–1 h reaction time. Higher reaction temperatures (>450 °C) or longer reaction times (>4 h) led to more gas products. The oil products consisted of olefins, paraffins, cyclics, and aromatics. About 80–90 wt % of the oil components had the same boiling point range as naphtha (25–200 °C) and heating values of 48–49 MJ/kg. Reaction pathways for converting model PP into oil under the tested conditions were proposed. Preliminary analyses indicate that this conversion process is net-energy positive and potentially has a higher energy efficiency and lower greenhouse gas emissions than incineration and mechanical recycling. The oil derived from PP has the potential to be used as gasoline blendstocks or feedstocks for other chemicals.
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IJS, KILJ, NUK, PNG, UL, UM
Many constructs in management studies, such as perceptions, personalities, attitudes, and behavioral intentions, are not directly observable. Typically, empirical studies measure such constructs ...using established scales with multiple indicators. When the scales are used in a different population, the items are translated into other languages or revised to adapt to other populations, it is essential for researchers to report the quality of measurement scales before using them to test hypotheses. Researchers commonly report the quality of these measurement scales based on Cronbach’s alpha and confirmatory factor analysis results. However, these results are usually inadequate and sometimes inappropriate. Moreover, researchers rarely consider sampling errors for these psychometric quality measures. In this best practice paper, we first critically review the most frequently-used approaches in empirical studies to evaluate the quality of measurement scales when using structural equation modeling. Next, we recommend best practices in assessing reliability, convergent and discriminant validity based on multiple criteria and taking sampling errors into consideration. Then, we illustrate with numerical examples the application of a specifically-developed R package, measureQ, that provides a one-stop solution for implementing the recommended best practices and a template for reporting the results. measureQ is easy to implement, even for those new to R. Our overall aim is to provide a best-practice reference for future authors, reviewers, and editors in reporting and reviewing the quality of measurement scales in empirical management studies.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The coronavirus disease 2019 (COVID-19) pandemic continues to have a tremendous impact on patients and healthcare systems around the world. In the fight against this novel disease, there is a ...pressing need for rapid and effective screening tools to identify patients infected with COVID-19, and to this end CT imaging has been proposed as one of the key screening methods which may be used as a complement to RT-PCR testing, particularly in situations where patients undergo routine CT scans for non-COVID-19 related reasons, patients have worsening respiratory status or developing complications that require expedited care, or patients are suspected to be COVID-19-positive but have negative RT-PCR test results. Early studies on CT-based screening have reported abnormalities in chest CT images which are characteristic of COVID-19 infection, but these abnormalities may be difficult to distinguish from abnormalities caused by other lung conditions. Motivated by this, in this study we introduce COVIDNet-CT, a deep convolutional neural network architecture that is tailored for detection of COVID-19 cases from chest CT images via a machine-driven design exploration approach. Additionally, we introduce COVIDx-CT, a benchmark CT image dataset derived from CT imaging data collected by the China National Center for Bioinformation comprising 104,009 images across 1,489 patient cases. Furthermore, in the interest of reliability and transparency, we leverage an explainability-driven performance validation strategy to investigate the decision-making behavior of COVIDNet-CT, and in doing so ensure that COVIDNet-CT makes predictions based on relevant indicators in CT images. Both COVIDNet-CT and the COVIDx-CT dataset are available to the general public in an open-source and open access manner as part of the COVID-Net initiative. While COVIDNet-CT is not yet a production-ready screening solution, we hope that releasing the model and dataset will encourage researchers, clinicians, and citizen data scientists alike to leverage and build upon them.
The failing human heart is characterized by metabolic abnormalities, but these defects remains incompletely understood. In animal models of heart failure there is a switch from a predominance of ...fatty acid utilization to the more oxygen-sparing carbohydrate metabolism. Recent studies have reported decreases in myocardial lipid content, but the inclusion of diabetic and nondiabetic patients obscures the distinction of adaptations to metabolic derangements from adaptations to heart failure per se.
We performed both unbiased and targeted myocardial lipid surveys using liquid chromatography-mass spectroscopy in nondiabetic, lean, predominantly nonischemic, advanced heart failure patients at the time of heart transplantation or left ventricular assist device implantation. We identified significantly decreased concentrations of the majority of myocardial lipid intermediates, including long-chain acylcarnitines, the primary subset of energetic lipid substrate for mitochondrial fatty acid oxidation. We report for the first time significantly reduced levels of intermediate and anaplerotic acyl-coenzyme A (CoA) species incorporated into the Krebs cycle, whereas the myocardial concentration of acetyl-CoA was significantly increased in end-stage heart failure. In contrast, we observed an increased abundance of ketogenic β-hydroxybutyryl-CoA, in association with increased myocardial utilization of β-hydroxybutyrate. We observed a significant increase in the expression of the gene encoding succinyl-CoA:3-oxoacid-CoA transferase, the rate-limiting enzyme for myocardial oxidation of β-hydroxybutyrate and acetoacetate.
These findings indicate increased ketone utilization in the severely failing human heart independent of diabetes mellitus, and they support the role of ketone bodies as an alternative fuel and myocardial ketone oxidation as a key metabolic adaptation in the failing human heart.
Objective Although medical management of acute uncomplicated type B aortic dissection remains the standard of care, contemporary data regarding the natural history of medically treated patients are ...sparse. The goal of this study was to evaluate the natural history of patients with acute type B aortic dissection who were initially managed with medical therapy alone. Methods All patients with acute type B aortic dissection who were initially managed medically between March 1999 and March 2011 were included. Failure of medical therapy was defined as any death or aorta-related intervention. Early failure occurred within 15 days of presentation. Predictors of long-term outcomes were determined using backward stepwise regression. Results A total of 298 patients with medically managed acute type B dissections were identified. The cohort had an average age of 65.9 years at presentation and was 61.7% male. There were 174 (58.4%) failures including 119 deaths and 87 interventions (24 endovascular, 63 open); 57 (66%) interventions were performed for aneurysmal degeneration. There were 37 (12%) early failures including 14 deaths and 25 interventions (10 endovascular, 15 open). Aneurysmal degeneration was the indication for intervention in six patients (24%). Mean follow-up was 4.2 years (range, 0.1-14.7 years). Kaplan-Meier estimate demonstrated that freedom from intervention was 77.3% ± 2.4% at 3 years and 74.2% ± 2.5% at 6 years. There were no predictors of freedom from intervention. Kaplan-Meier estimate demonstrated that the intervention-free survival was 55.0% ± 3.0% at 3 years and 41.0% ± 3.2% at 6 years. End-stage renal disease was predictive of failure of medical treatment (hazard ratio, 2.60; confidence interval, 1.19-5.66; P = .02), and age >70 years was protective against failure (hazard ratio, 0.97; confidence interval, 0.95-0.98; P < .01). Kaplan-Meier estimate demonstrated that survival after 6 years was higher in patients who underwent interventions (76% vs 58%; P = .018). Conclusions The majority of patients with acute type B dissection will fail medical therapy over time as evidenced by a 6-year intervention-free survival of 41%. Patients who underwent any aortic intervention had a significant survival advantage over those who were treated with medical management alone. Further study is necessary to determine who will benefit most from early intervention.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Overuse of screening colonoscopy increases cost and procedural adverse events, but inadequate surveillance can miss the development of colorectal cancer. We measured compliance with the 2020 U.S. ...Multi-Society Task Force on Colorectal Cancer (USMSTF) polypectomy surveillance guidelines in clinical records and a survey.
We performed a retrospective study comparing surveillance intervals for first-time average-risk colonoscopies with the 2020 USMSTF guidelines. Cases were analyzed from 3 intervals (March 2021 to May 2021, November 2021 to January 2022, and April 2022 to May 2022), collectively termed the postguideline period, and a baseline period from November 2019 to January 2020. Real-world compliance rates were compared with results of a survey conducted between November 2020 and February 2021.
Overall compliance was 48.9% among 532 colonoscopies, ranging from 8.3% for low-risk adenomas (LRAs), 88.3% for high-risk adenomas, 63.1% for sessile serrated polyps (SSPs), and 88.6% for hyperplastic polyps. Compliance for LRA increased from the baseline period (.8% vs 8.3%, P = .003), and 95.3% of nonadherent LRA cases followed the 2012 USMSTF guidelines. Compliance for LRAs was 18.6% among respondents who provided a compliant surveillance interval for LRAs in the survey. Noncompliance was associated with finishing training >10 years ago (odds ratio, 1.9; 95% confidence interval, 1.4-2.7) and performing over 800 colonoscopies annually (odds ratio, 2.0; 95% confidence interval, 1.5-2.6).
Adoption of the 2020 USMSTF surveillance guidelines remains low at 2 years. Further research into outcomes for patients with LRAs and SSPs may increase guideline adoption.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Background Merkel cell carcinoma (MCC) is an aggressive skin cancer with a mortality of 33%. Advanced disease at diagnosis is a poor prognostic factor, suggesting that earlier detection may improve ...outcome. No systematic analysis has been published to define the clinical features that are characteristic of MCC. Objective We sought to define the clinical characteristics present at diagnosis to identify features that may aid clinicians in recognizing MCC. Methods We conducted a cohort study of 195 patients given the diagnosis of MCC between 1980 and 2007. Data were collected prospectively in the majority of cases, and medical records were reviewed. Results An important finding was that 88% of MCCs were asymptomatic (nontender) despite rapid growth in the prior 3 months (63% of lesions) and being red or pink (56%). A majority of MCC lesions (56%) were presumed at biopsy to be benign, with a cyst/acneiform lesion being the single most common diagnosis (32%) given. The median delay from lesion appearance to biopsy was 3 months (range 1-54 months), and median tumor diameter was 1.8 cm. Similar to earlier studies, 81% of primary MCCs occurred on ultraviolet-exposed sites, and our cohort was elderly (90% >50 years), predominantly white (98%), and often profoundly immune suppressed (7.8%). An additional novel finding was that chronic lymphocytic leukemia was more than 30-fold overrepresented among patients with MCC. Limitations The study was limited to patients seen at a tertiary care center. Complete clinical data could not be obtained on all patients. This study could not assess the specificity of the clinical characteristics of MCC. Conclusions To our knowledge, this study is the first to define clinical features that may serve as clues in the diagnosis of MCC. The most significant features can be summarized in an acronym: AEIOU ( a symptomatic/lack of tenderness, e xpanding rapidly, i mmune suppression, o lder than 50 years, and u ltraviolet-exposed site on a person with fair skin). In our series, 89% of primary MCCs had 3 or more of these findings. Although MCC is uncommon, when present in combination, these features may indicate a concerning process that would warrant biopsy. In particular, a lesion that is red and expanding rapidly yet asymptomatic should be of concern.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
Patients with homozygous Phe508del cystic fibrosis were assigned to receive combination tezacaftor–ivacaftor or placebo for 24 weeks. The combination resulted in an FEV
1
that was 4 percentage points ...higher and a pulmonary-exacerbation rate that was 35% lower than with placebo.
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