scholarly journals A comparison of performance metrics for cloth masks as source control devices for simulated cough and exhalation aerosols

2021 ◽  
pp. 1-21
Author(s):  
William G. Lindsley ◽  
Francoise M. Blachere ◽  
Donald H. Beezhold ◽  
Brandon F. Law ◽  
Raymond C. Derk ◽  
...  
Keyword(s):  
Performance Metrics ◽  
Source Control ◽  
Control Devices

scholarly journals A comparison of performance metrics for cloth face masks as source control devices for simulated cough and exhalation aerosols

2021 ◽  
Author(s):  
William G. Lindsley ◽  
Francoise M. Blachere ◽  
Donald H. Beezhold ◽  
Brandon F. Law ◽  
Raymond C. Derk ◽  
...  
Keyword(s):  
Performance Metrics ◽  
Construction Materials ◽  
Correlation Coefficients ◽  
Filtration Efficiency ◽  
The Other ◽  
Source Control ◽  
Control Performance ◽  
Control And Prevention ◽  
Control Devices ◽  
Alternative Metrics

AbstractUniversal mask wearing is recommended by the Centers for Disease Control and Prevention to help control the spread of COVID-19. Masks reduce the expulsion of respiratory aerosols (called source control) and offer some protection to the wearer. However, masks vary greatly in their designs and construction materials, and it is not clear which are most effective. Our study tested 15 reusable cloth masks (which included face masks, neck gaiters, and bandanas), two medical masks, and two N95 filtering facepiece respirators as source control devices for aerosols ≤ 7 µm produced during simulated coughing and exhalation. These measurements were compared with the mask filtration efficiencies, airflow resistances, and fit factors. The source control collection efficiencies for the cloth masks ranged from 17% to 71% for coughing and 35% to 66% for exhalation. The filtration efficiencies of the cloth masks ranged from 1.4% to 98%, while the fit factors were 1.3 to 7.4 on an elastomeric manikin headform and 1.0 to 4.0 on human test subjects. The correlation coefficients between the source control efficacies and the other performance metrics ranged from 0.31 to 0.66 and were significant in all but one case. However, none of the alternative metrics were strong predictors of the source control performance of cloth masks. Our results suggest that a better understanding of the relationships between source control performance and metrics like filtration efficiency, airflow resistance, and fit factor are needed to develop simple methods to estimate the effectiveness of masks as source control devices for respiratory aerosols.

scholarly journals Face mask fit modifications that improve source control performance

2021 ◽  
Author(s):  
Francoise M. Blachere ◽  
Angela R. Lemons ◽  
Jayme P. Coyle ◽  
Raymond C. Derk ◽  
William G. Lindsley ◽  
...  
Keyword(s):  
Measurement System ◽  
Human Subjects ◽  
Face Mask ◽  
Source Control ◽  
Control Performance ◽  
Control Measurement ◽  
Infected People ◽  
Control Devices

BACKGROUND During the COVID-19 pandemic, face masks are used as source control devices to reduce the expulsion of respiratory aerosols from infected people. Modifications such as mask braces, earloop straps, knotting and tucking, and double masking have been proposed to improve mask fit however the data on source control are limited. METHODS The effectiveness of mask fit modifications was determined by conducting fit tests on human subjects and simulator manikins and by performing simulated coughs and exhalations using a source control measurement system. RESULTS Medical masks without modification blocked ≥56% of cough aerosols and ≥42% of exhaled aerosols. Modifying fit by crossing the earloops or placing a bracket under the mask did not increase performance, while using earloop toggles, an earloop strap, and knotting and tucking the mask increased performance. The most effective modifications for improving source control performance were double masking and using a mask brace. Placing a cloth mask over a medical mask blocked ≥85% of cough aerosols and ≥91% of exhaled aerosols. Placing a brace over a medical mask blocked ≥95% of cough aerosols and ≥99% of exhaled aerosols. CONCLUSION Fit modifications can greatly improve the performance of face masks as source control devices for respiratory aerosols.

scholarly journals Efficacy of face masks, neck gaiters and face shields for reducing the expulsion of simulated cough-generated aerosols

2020 ◽  
Author(s):  
William G. Lindsley ◽  
Francoise M. Blachere ◽  
Brandon F. Law ◽  
Donald H. Beezhold ◽  
John D. Noti
Keyword(s):  
Double Layer ◽  
Aerosol Particles ◽  
Single Layer ◽  
Face Mask ◽  
Cotton Cloth ◽  
Source Control ◽  
The Face ◽  
Community Transmission ◽  
Small Aerosol ◽  
Control Devices

AbstractFace masks are recommended to reduce community transmission of SARS-CoV-2. One of the primary benefits of face masks and other coverings is as source control devices to reduce the expulsion of respiratory aerosols during coughing, breathing, and speaking. Face shields and neck gaiters have been proposed as an alternative to face masks, but information about face shields and neck gaiters as source control devices is limited. We used a cough aerosol simulator with a pliable skin headform to propel small aerosol particles (0 to 7 µm) into different face coverings. An N95 respirator blocked 99% of the cough aerosol, a medical grade procedure mask blocked 59%, a 3-ply cotton cloth face mask blocked 51%, and a polyester neck gaiter blocked 47% as a single layer and 60% when folded into a double layer. In contrast, the face shield blocked 2% of the cough aerosol. Our results suggest that face masks and neck gaiters are preferable to face shields as source control devices for cough aerosols.

scholarly journals Efficient and safe substrates for black soldier fly biowaste treatment along circular economy principles

Detritus ◽  
2021 ◽  
pp. 31-40
Author(s):  
Moritz Gold ◽  
David Ireri ◽  
Christian Zurbrugg ◽  
Trevor Fowles ◽  
Alexander Mathys
Keyword(s):  
Food Waste ◽  
Web Application ◽  
Performance Metrics ◽  
Animal Feed ◽  
Animal Manure ◽  
Nutritional Composition ◽  
Environmental Benefits ◽  
Source Control ◽  
Process Performance ◽  
Black Soldier Fly

Black soldier fly larvae (BSFL) treatment is an emerging technology for the valorisation of nutrients from biowaste. Selecting suitable substrates for BSFL treatment is a frequent challenge for researchers and practitioners. We conducted a systematic assessment of BSFL treatment substrates in Nairobi, Kenya to source more substrate for upscaling an existing BSFL treatment facility. The applied approach is universal and considers four criteria: 1) substrate availability and costs, 2) BSFL process performance, 3) product safety, and 4) waste recovery hierarchy. Data were collected from previous waste assessments or semi-structured key informant interviews and sight tours of waste producers. Waste nutritional composition and BSFL process performance metrics were summarised in the “BSFL Substrate Explorer”, an open-access web application that should facilitate the replication of such assessments. We show that most biowaste in Nairobi is currently not available for facility upscaling due to contamination with inorganics and a lack of affordable waste collection services. A mixture of human faeces, animal manure, fruit/vegetable waste, and food waste (with inorganics) should be pursued for upscaling. These wastes tend to have a lower treatment performance, but in contrast to cereal-based byproducts, food industry byproducts, and segregated food waste, there is no conflict with animal feed utilization. The traceability of substrates, source control, and post-harvest processing of larvae are required to ensure feed safety. The criteria presented here ensures the design of BSFL treatment facilities based on realistic performance estimates, the production of safe insect-based products, and environmental benefits of products compared to the status quo.

Framework for rare event detection using Artificial Neural Network based context free grammar

2020 ◽  
Vol 39 (6) ◽  
pp. 8463-8475
Author(s):  
Palanivel Srinivasan ◽  
Manivannan Doraipandian
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Event Detection ◽  
Performance Metrics ◽  
Rare Events ◽  
Rare Event ◽  
Video Stream ◽  
Context Free Grammar ◽  
Artificial Neural ◽  
Context Free

Rare event detections are performed using spatial domain and frequency domain-based procedures. Omnipresent surveillance camera footages are increasing exponentially due course the time. Monitoring all the events manually is an insignificant and more time-consuming process. Therefore, an automated rare event detection contrivance is required to make this process manageable. In this work, a Context-Free Grammar (CFG) is developed for detecting rare events from a video stream and Artificial Neural Network (ANN) is used to train CFG. A set of dedicated algorithms are used to perform frame split process, edge detection, background subtraction and convert the processed data into CFG. The developed CFG is converted into nodes and edges to form a graph. The graph is given to the input layer of an ANN to classify normal and rare event classes. Graph derived from CFG using input video stream is used to train ANN Further the performance of developed Artificial Neural Network Based Context-Free Grammar – Rare Event Detection (ACFG-RED) is compared with other existing techniques and performance metrics such as accuracy, precision, sensitivity, recall, average processing time and average processing power are used for performance estimation and analyzed. Better performance metrics values have been observed for the ANN-CFG model compared with other techniques. The developed model will provide a better solution in detecting rare events using video streams.

Education and the Relation to the Outside: A Little Real Reality

2015 ◽  
Vol 9 (3) ◽  
pp. 273-300 ◽  
Author(s):  
David Savat ◽  
Greg Thompson
Keyword(s):  
Performance Metrics ◽  
Online Courses ◽  
Massive Open Online Courses ◽  
Educational Institutions ◽  
Special Issue ◽  
Massive Open Online ◽  
Transformative Teaching ◽  
Control Society ◽  
Brave New World ◽  
Radical Transformation

One of the more dominant themes around the use of Deleuze and Guattari's work, including in this special issue, is a focus on the radical transformation that educational institutions are undergoing, and which applies to administrator, student and educator alike. This is a transformation that finds its expression through teaching analytics, transformative teaching, massive open online courses (MOOCs) and updateable performance metrics alike. These techniques and practices, as an expression of control society, constitute the new sorts of machines that frame and inhabit our educational institutions. As Deleuze and Guattari's work posits, on some level these are precisely the machines that many people in their day-to-day work as educators, students and administrators assemble and maintain, that is, desire. The meta-model of schizoanalysis is ideally placed to analyse this profound shift that is occurring in society, felt closely in the so-called knowledge sector where a brave new world of continuous education and motivation is instituting itself.

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