Heterogeneity in transmissibility and shedding SARS-CoV-2 via droplets and aerosols

Background: Which virological factors mediate overdispersion in the transmissibility of emerging viruses remains a longstanding question in infectious disease epidemiology. Methods: Here, we use systematic review to develop a comprehensive dataset of respiratory viral loads (rVLs) of SARS-CoV-2, SARS-CoV-1 and influenza A(H1N1)pdm09. We then comparatively meta-analyze the data and model individual infectiousness by shedding viable virus via respiratory droplets and aerosols. Results: The analyses indicate heterogeneity in rVL as an intrinsic virological factor facilitating greater overdispersion for SARS-CoV-2 in the COVID-19 pandemic than A(H1N1)pdm09 in the 2009 influenza pandemic. For COVID-19, case heterogeneity remains broad throughout the infectious period, including for pediatric and asymptomatic infections. Hence, many COVID-19 cases inherently present minimal transmission risk, whereas highly infectious individuals shed tens to thousands of SARS-CoV-2 virions/min via droplets and aerosols while breathing, talking and singing. Coughing increases the contagiousness, especially in close contact, of symptomatic cases relative to asymptomatic ones. Infectiousness tends to be elevated between 1-5 days post-symptom onset. Conclusions: Intrinsic case variation in rVL facilitates overdispersion in the transmissibility of emerging respiratory viruses. Our findings present considerations for disease control in the COVID-19 pandemic as well as future outbreaks of novel viruses.</p

Role of biomarkers and emerging technologies in defining and assessing neurobiological recovery after sport-related concussion: a systematic review

OBJECTIVE: Determine the role of fluid-based biomarkers, advanced neuroimaging, genetic testing and emerging technologies in defining and assessing neurobiological recovery after sport-related concussion (SRC). DESIGN: Systematic review. DATA SOURCES: Searches of seven databases from 1 January 2001 through 24 March 2022 using keywords and index terms relevant to concussion, sports and neurobiological recovery. Separate reviews were conducted for studies involving neuroimaging, fluid biomarkers, genetic testing and emerging technologies. A standardised method and data extraction tool was used to document the study design, population, methodology and results. Reviewers also rated the risk of bias and quality of each study. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies were included if they: (1) were published in English; (2) represented original research; (3) involved human research; (4) pertained only to SRC; (5) included data involving neuroimaging (including electrophysiological testing), fluid biomarkers or genetic testing or other advanced technologies used to assess neurobiological recovery after SRC; (6) had a minimum of one data collection point within 6 months post-SRC; and (7) contained a minimum sample size of 10 participants. RESULTS: A total of 205 studies met inclusion criteria, including 81 neuroimaging, 50 fluid biomarkers, 5 genetic testing, 73 advanced technologies studies (4 studies overlapped two separate domains). Numerous studies have demonstrated the ability of neuroimaging and fluid-based biomarkers to detect the acute effects of concussion and to track neurobiological recovery after injury. Recent studies have also reported on the diagnostic and prognostic performance of emerging technologies in the assessment of SRC. In sum, the available evidence reinforces the theory that physiological recovery may persist beyond clinical recovery after SRC. The potential role of genetic testing remains unclear based on limited research. CONCLUSIONS: Advanced neuroimaging, fluid-based biomarkers, genetic testing and emerging technologies are valuable research tools for the study of SRC, but there is not sufficient evidence to recommend their use in clinical practice. PROSPERO REGISTRATION NUMBER: CRD42020164558

Oxidative Dehydrogenation of Alkanes by O2 and H2S

Propylene and other light olefins are an important class of compounds in the petrochemical industry. Currently, the majority of the world’s propylene production comes from the cracking of hydrocarbons, where propylene is a co-product of the process. With increasing demand for propylene, interest in developing on-demand processes geared specifically towards propylene production has increased. Oxidative dehydrogenation is a process that has the potential to overcome many of the limitations of catalytic dehydrogenation. The objective of this work is to study the reaction between propane, butane or mixtures of the two alkanes with O2 and H2S to produce propylene with high selectivity and conversion and to obtain an understanding of all aspects of the process. The experiments were carried out using various feeds containing either N2/HC, N2/HC/O2, N2/HC/H2S, N2/HC/O2/H2S (Where HC = C3H8 or C4H10) through a tubular reactor at 5-200 ms residence/contact times in the 823-1023 K temperature range. Analysis of the gases was carried out by gas chromatography. The addition of ~ 5% H2S to a stream of C3H8 (~61% N2/36% C3H8) caused an increase in the conversion of C3H8 at 1023 K at a contact time of 35 ms. An increase in C3H6 selectivity by 7% and a decrease in C2H4 selectivity by 6% were also observed. The overall yield of C3H6 more than doubled. Addition of a catalyst enhanced the conversion of C3H8 and selectivity to C3H6 at 923 K; however, conversions at this temperature range were too low to be of industrial use. At 1023 K, thermal contributions took over and the results obtained were very similar to those obtained for the gas-phase reaction. Addition of H2S to the reaction between C3H8 and O2 caused a significant enhancement in the selectivity towards C3H6 and a decreased selectivity towards C2H4. The presence of propylene suggested that this reaction was not operating in a thermodynamic regime, as propylene is a partial oxidation product and in a purely thermodynamic regime, solid carbon or carbon oxides would be the most favored carbon products. Finally, the effect of H2S on the reactions between C4H10 and O2 was studied in the gas-phase and over a vanadium catalyst, respectively. Surprisingly, the results showed a significant enhancement in the selectivity to C3H6 in the presence of H2S. In addition, increased conversion of C4H10 was also observed due to the addition of H2S to the reactant feed gas, and combined with the enhanced selectivity to C3H6, it resulted in an increased yield of C4-C3 olefins. The reaction between C3-C4 alkanes, O2 and H2S has the potential to overcome some of the limitations of ODH by O2 alone, as reduced selectivity to carbon oxides, increased conversion level of the alkane and improved selectivity to propylene were observed. The gas-phase reactions involving H2S were observed to be efficient at higher temperatures hence removing the need for the vanadia catalyst from this system. Since all reactant gases are readily available at a Claus plant, this research opens the door to the idea of a small-scale on-demand process for propylene production using cheap raw materials that are already available on-site

Examining the meaning and methodological characteristics of the systematized review label: A scoping review protocol.

IntroductionA large portion of published evidence syntheses (ES) do not conform to established standards. There is a growing number of reviews labeled as a "systematized review", but authors do not always identify specific methodological adaptations or specify the biases these may introduce.ObjectiveThe objective of this scoping review is to identify which methodological attributes common to evidence syntheses (ES) are implemented or referenced in published systematized reviews. It also aims to 1) identify and collate, where available, the reasons authors characterize their study as a systematized review 2) determine whether any justifications provided were based on resource constraints or research goals, and 3) describe common characteristics of systematized reviews.Inclusion criteriaAll articles that are titled as a systematized review, attempt a collocation and synthesis of existing literature, and include some methodology for their review process, will be included.Materials and methodsA title search will be conducted for the terms "systematized" or "systematised" in proximity to the term "review" in a selection of scholarly sources that offer broad coverage of literature in many disciplines: Google Scholar, Lens, Web of Science Core Collection (Web of Science platform), Scopus (Elsevier platform), MEDLINE (Ovid platform). Screening and data extraction will be done in duplicate. Screening will be conducted in Covidence. Data extraction will be done in Google sheets. Data extraction elements will include common methodological characteristics relating to various steps of the evidence synthesis process. Descriptive, aggregate statistics, and categorization of reasons for selecting the systematized review type are the primary planned analysis for this review.Data availabilityThis is a registered report protocol. The data collected in this research project will be made available in the Borealis repository (https://borealisdata.ca/) upon finalization of the study

Data Management for Systematic Reviews: Guidance is Needed

Data management practices for systematic reviews and other types of knowledge syntheses are variable, with some reviews following open science practices and others with poor reporting practices leading to lack of transparency or reproducibility. Reporting standards have improved the level of detail being shared in published reviews, and also encourage more open sharing of data from various stages of the review process. Similar to project planning or completion of an ethics application, systematic review teams should create a data management plan alongside creation of their study protocol. This commentary provides a brief description of a Data Management Plan Template created specifically for systematic reviews. It also describes the companion LibGuide which was created to provide more detailed examples, and to serve as a living document for updates and new guidance. The creation of the template was funded by the Portage Network

Systematic reviews

PowerPoint slidesIn this PDW, we will offer an asynchronous training session on how to design systematic literature reviews, describing methodological innovations for conducting them and more rigorous standards for reporting them. First, we will discuss the purpose of systematic literature reviews (compared to other types of literature reviews) and their relevance for advancing management scholarly efforts. Second, we will illuminate why most literature reviews often fall short of their potential, and how unrecognized variance in methodological rigor undermines the usefulness of different types of reviews for evidence- based management. Third, we will present techniques and approaches for conducting systematic literature reviews; in doing so we show how adoption of advanced systematic review practices facilitate an accumulated body of knowledge to guide in management scholarship and practice. The PowerPoint slides included here are for the training aspect of this workshop, presented at the Academy of Management annual conference 2020

Evidence synthesis and systematic reviews support toolkit

This toolkit contains resources, templates and other useful materials for researchers undertaking evidence synthesis projects such as systematic or scoping review

What is "Systematic" about Systematic Literature Reviews?

This presentation focused on defining what systematic reviews are, explaining the different types of knowledge syntheses, discussing organizations involved with systematic reviews, defining the steps involved with systematic reviews, providing a deep dive into the search and search strategy portion of a systematic review, providing info on the study selection stage of an SR, and an overview of reporting standards used within this process.Presented virtually at the 80th Annual Meeting of the Academy of Management</div

Systematic Reviews Workshop Series - Lesson plans

These are the lesson plans for each of the 3 workshops that make up the Systematic Reviews workshop series. Initially developed in Spring/Summer 2019, and adapted for the Zoom environment in 2020.Othe