N95 Masks and Re-Use

Recent pandemic developments have strained the supply of N95 filtering facepiece respirators (FFRs), which protect users from particles and aerosols in the air that they breathe. Technically, they must filter out at least 95% of 0.3 micrometre particles.

Normally these are meant to be single-use devices, and are removed and disposed of in a secure way to prevent infection transmission. However, with supply shortages people are considering or resorting to re-using these FFRs, possibly with some sort of chemical or physical disinfection process. Disinfection processes are never 100% effective, so this is not a great option, but I guess it’s better than having no protection.

One disinfection method that I’m very familiar with is UV-C disinfection, having done research in the area of photochemical processes for several decades. There is published literature available demonstrating reasonable disinfection success for UV when applied to N95 FFRs, so this may be an approach to consider if necessary.

I’m working on an overview of this literature (draft version now available at this link), but I’m happy to consult (pro bono) with health care institutions that are considering UV applications to deal with their situations (wanderson@uwaterloo.ca).

Handwashing

With the recent development of a viral pandemic, people are being reminded about the importance of handwashing for infection prevention. Coincidentally, in 2019 my colleague Prof. Marc Aucoin and I supervised a research study on handwashing for the CSA Group, a product standards organization. Specifically, our study aimed to determine if the faucet water flow rate had a significant effect on the ability of handwashing to remove bacteria from the skin.

You can access and read the full report on their website. The bottom line is that no, the water flow rate from the faucet didn’t have a significant effect over the range we tested, from 0.5 to 2.2 gallons per minute (about 2 to 8 litres per minute). Under all of those flow rates, on average about 99.3% of E. coli bacteria would be removed from the hands, which is good to know.

To do this study, we had to control all the other variables as much as possible, including the water temperature, and the amount and type of hand soap used by each person. The other big factor is the way that the hands were washed, including the length of time. For this study, we used a certain protocol from Public Health, and everyone involved in the study learned how to properly wash their hands. This was a good learning opportunity for people, including me, and so I reproduce the protocol that we used below. It’s a useful skill to know how to thoroughly wash your hands these days.

Recommended handwashing technique for infection prevention.

Graduation Rates Revisited

My blog statistics show that an old post from 2013 on Engineering Failure Rates continues to be a popular one to visit. There is an updated one available too, from 2018. As those blogs note, the data is from Ontario’s CUDO website and their definition of “success” is rather broad. If you start in Engineering, and graduate within 7 years from the SAME university with ANY degree, that counts as success for degree completion. So, if you start in Engineering then switch and graduate with a degree in Music, that’s success. However, if you start in Engineering, then leave before graduation to complete a Veterinary degree at Guelph, that’s not a successful degree completion for their statistics. So if you look at those statistics, you need to be aware of what they actually mean (or don’t mean)!

Those statistics always bothered me, so I came up with an alternative measure of Engineering graduation rates, using the same CUDO data source. My hypothesis is that if we use the Engineering first year registration data for a certain year, and then compare that with the Engineering “degrees conferred” data four years later, then that will give us a rough estimate of “success”, specifically within Engineering programs as a whole.

So that’s what I did with downloads from the CUDO website, with the admission data from 2006 to 2012, and the degrees conferred data from 2010 to 2017. (I used a 5 year comparison for Waterloo, since our program takes 5 years to complete when you include the co-op work experience. All other universities can be completed in 4 years, so I used that comparison for the rest.) Based on this approach, we can summarize the results in the graph below, showing average degree completion rates. The “error bars” show plus and minus one standard deviation of the average “success rates” for each university (a measure of how variable the results are).

I call the graph “apparent success rates” because it still doesn’t use individual student data; it’s based on bulk numbers that can hide a lot of variables. Indeed, as we gaze at the graph we see some obviously puzzling results. The Engineering programs at Windsor and Lakehead are highly successful at graduating more engineering students then they admit!

Clearly there are some problems with this data analysis. For one, it doesn’t take into account the fact that some students at other universities can do an optional co-op or internship that will delay their graduation by a year. Secondly, it is based on first year registration data for each engineering program. This means that the students who transfer into Engineering from other programs within the University, or from other universities, are not counted. Likely this explains the ones where the graduation/success rates are over 100%, and may be a factor for those who have rates approaching 100%.

I have no deep insights into the other universities, but for Waterloo I know that in my experience we have extremely few transfers from other Universities, and very few from other programs at Waterloo. Therefore the average success/graduation rate at Waterloo of around 78% is likely a reasonable ballpark estimate for the fraction of new admits that graduate in 5 years.

This all just illustrates once again that defining “success” is complicated, and getting meaningful data to measure “success” is even harder. We just have to make do with what we can get, and recognize the limitations of the data.

Applying to University: Done Your Homework Yet?

For those applying to university for Fall 2020 admission, there is some homework you should have done, or at least started by now. Arguably, this is probably the most important homework that you have, even if no one has explicitly assigned it or told you to do it. Properly done, this homework will make success in university more likely. So what is this homework?

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The Recycling Economy

Resource Recovery Partnership Conference

For the sixth year, I’ve been helping organize the “Resource Recovery Partnership” conference in collaboration with industry, government, and academic colleagues. This year’s event is on Thursday September 19, 2019, and registration is free for either in-person or webcast attendance. The final agenda is available, and anyone interested in the ideas behind sustainable materials, recycling, circular economy, zero waste, or materials and energy recovery might want to attend some of the webcast sessions. There are a range of speakers and panelists covering various aspects of policy development, technologies, and current statistics and trends. The talks are not highly technical, and anyone could benefit from some of the insights available here.

As our landfills (and oceans) fill with wastes, it has become clear to most people that solutions are needed to reduce wastes and to recover some value from the remaining waste materials. This is easier said than done, and requires a comprehensive approach incorporating technology, smart policies, economic drivers, and societal buy-in. These conferences have tried to bring together people from a wide range of backgrounds and interests, to try to advance progress in waste reduction. It’s a long and slow progress, but momentum seems to be building around the globe.

Campus Tours

Anyone considering applying to a university should visit it, if at all possible. Many people visit campus during the summer vacation period. This is convenient for travel, but not always the best time to get an impression, because most campuses are very quiet during the summer. Waterloo is a bit of an exception, since we have classes going throughout the summer for returning co-op students in engineering and other programs.

The fall is probably a better time for a visit, when things are more active and you can get a good feel for the campus in actual operation. Take a day or two off high-school classes and visit a campus! If you’ve never been on a campus visit try the closest one to home, even if you don’t intend to apply there. It’s good to get a practice visit so you know what to expect when you go to other places of more direct interest.

Of course, in some cases it’s not practical or financially feasible to visit a campus that you’re interested in. In that case, using online videos is one way to get a bit of a tour. I think that most universities have some sort of video tour availability. Here’s a recent video made by one of our own class of 1998 civil engineering alumni, Fanny Dunagan. It’s interesting to see what captured her attention when returning for a visit.

Enhanced Mobility Wheelchair wins first-place at the 2019 IDeA competition

A nice example of mechanical engineering students using their skills to solve real-world problems. See the link below for more details.

Five mechanical engineering students created the Enhanced Mobility Wheelchair for their 2019 capstone design project, and now their work is being nationally recognized for improving accessibility and inclusivity in Canada.

Wheelchair users often face challenges when deciding which device to use to get around. Regular wheelchairs are easy to manoeuvre, but hand-cycle wheelchairs offer better speed efficiency. The Enhanced Mobility Wheelchair team has designed and prototyped an augmented wheelchair that provides users with the comfort and maneuverability of a traditional wheelchair while offering the speed of a hand-cycle wheelchair. The novel drive system provides greater ergonomic support and promotes good posture even when the operator is tired. Selectable gear ratios greatly improve motion efficiency on a variety of terrain, helping those confined to a wheelchair go further and faster than ever before.

Source: Enhanced Mobility Wheelchair wins first-place at the 2019 IDeA competition | Waterloo Stories | University of Waterloo