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Surviving The Pandemic As A Hacker: Peering Behind The Mask

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We’re now several months into the global response to the COVID-19 pandemic, with most parts of the world falling somewhere on the lockdown/social distancing/opening up path.

It’s fair to say now that while the medical emergency has not passed, the level of knowledge about it has changed significantly. When communities were fighting to slow the initial spead, the focus was on solving the problem of medical protection gear and other equipment shortages at all costs with some interesting yet possibly hazardous solutions. Now the focus has moved towards protecting the general public when they do need to venture out, and as society learns to get life moving again with safety measures in place.

So, we all need masks of some sort. What type to do you need? Is one type better than another? And how do we all get them when everyone suddenly needs what was once a somewhat niche item?

Masks Offer Basic Protection for Everyone in Public Areas

It’s rather sickening to look at the quantity of droplets expelled by a sneeze. James Gathany / Public domain

Some parts of the world are coming to terms with the effects of long term lockdown, while others are beginning to contemplate how they might start moving back towards some kind of normality. The issue of mask wearing a practical one, because there are indications that it will slow the spread of the disease.

When considering face masks, it’s important to start by defining what a mask for the general public should be, and what it is trying to achieve. This is not the same breed as the masks worn by intensive care staff where the primary intention is to protect the wearer by filtering the virus from an atmosphere heavily contaminated with it, instead it is a mask intended to be worn in environments where only a few people may be spreading the virus (with the pesky detail of not knowing who those few people are).

The goal of masks is to reduce the chances of transmission by infected droplets. It’s an idea wittily illustrated in the “Urine Test” meme, that such a mask will not guarantee your escape from the virus but it should significantly reduce the odds of its transmission. We’re told that these odds tilt further against the virus the more people in an environment wear a mask, and since it’s a relatively easy step to take it’s one that everyone should be taking as a courtesy to your fellow humans.

We’re Makers, Yes… But You Can Learn a Lot From Commercial Masks

In our community the first thought turns invariably towards making our own and indeed that’s part of the official advice in many territories, but before we go there it’s worth considering the commercial alternatives. These normally use a composite design featuring multiple layers of fabric for comfort and filtration, with the main filter layer(s) being of a blown fabric rather than a woven one.

A variety of commercial masks, left to right: FFP3 industrial dust mask, T32610-2016 surgcal-style mask, very cheap unrated single layer dust mask.ic
A variety of commercial masks, left to right: FFP3 industrial dust mask, T32610-2016 surgical-style mask, very cheap unrated single layer dust mask.

If you have a supply of the top-spec medical masks then you’re all set, but since pandemic demand has caused a supply shortage that’s a luxury most of us can’t claim and shouldn’t be taking from the professionals who need them anyway. We will often have an array of other masks to hand as dust protection in the workshop, and among these can be found some surprisingly good protection for our application. The key is in the rating which should be printed on the box or the outside of the mask, but to decode what it means will sometimes require a bit of digging into the world of international standards.

Assuming that you didn’t buy from the cheapest seller on AliExpress and your mask isn’t counterfeit, you may encounter US standards (N95 etc), EU standards (EN149, FFP etc.), or Chinese standards (T3210-2016 etc.). These deal among other properties with the mask’s particulate filtration ability both in terms of particle size and percentage removal, and with the breathing force required to make air pass through them. Happily our requirement for a droplet-catcher does not require the most stringent of standards. As an aside, the official versions of all the above mentioned standards seem all to be behind very expensive paywalls. It’s not difficult to find them online through your search engine though.

Tearing Down Some Masks

Five layers in this FFP3 dust mask.
Five layers in this FFP3 dust mask.

So casting around the commercial masks we have to hand here brings out a pair of dust masks and a surgical style mask that admirably illustrate the range on offer. An FFP3 dust mask is a European-rated rough equivalent of those N95 surgical masks in industrial form, and it feels thick between finger and thumb. Despite having probably the best available filtration, our FFP3 is not suitable as virus protection because it manages exhalation through a non-return valve that would release droplets into the atmosphere.

Taking the used FFP3 mask from my overall pocket that has protected me from dust during several woodwork machining sessions at MK Makerspace and cutting it open, it is revealed as having five non-woven layers including a thick and fluffy one and a very dense one. When compressed with a micrometer screw gauge its thickness is a relatively substantial 0.94mm.

Three layers in this T32610-2016 surgical-style mask.
Three layers in this T32610-2016 surgical-style mask.

The next mask up for dissection is a Chinese-manufactured three-layer surgical mask with T3210-2016 spec, whose box clearly states that it isn’t a medical device. That warning sounds concerning but in this case it isn’t; masks to that particular standard are intended to be worn by the general public and not by medical staff. In fact this mask is purpose-made as everyday-life dust and droplet-catching PPE, so is just the job. Cutting it open reveals three layers with the middle filter layer being a dense non-woven fabric, and the micrometer reveals it to have a svelte 0.28mm compressed thickness.

The final mask is another dust mask, a Silverline single-layer mask from a pack I bought for showing people round a dusty church tower. It’s a single layer of 0.45mm thick stiff blown-polymer fabric moulded into a mask shape, and its packaging has the ominous warning that it does not offer rated protection to the wearer. It was very cheap indeed and just about adequate for the purpose I bought it for, but I have to admit I’d be happier with more than its very basic level of protection during the pandemic.

With steamed up glasses and an unruly lockdown hairstyle, illustrating the importance of a good seal round the nose.
With steamed up glasses and an unruly lockdown hairstyle, illustrating the importance of a good seal round the nose.

All three masks feature a piece of stiff wire or metal strip above the nose designed to fit the contours of the bridge of the nose and clamp shut any gaps through which breath can escape. It’s easy to tell whether they are effective if you wear glasses, because they will immediately steam up if damp air from your breath escapes. Of the three it was the disposable surgical-style mask that did the worst job of this, the FFP3 had a very sturdy plastic and wire tape that lets nothing through and the cheap unrated mask has a metal strip, but the surgical-style mask’s single piece of thin wire simply isn’t up to the job.

I’ve worn all three for extended periods of time to test them, and while driving into town for a prescription wearing this one I had to stop and take it off as the risk of not seeing where I was going became too great. This can be mitigated with folded-up kitchen towel to plug the gaps or even medical tape to secure it, but such things rapidly become very annoying.

As for the fogging, there is some advice out there for this as well. Using dish soap that does not have lotion in it, or say that it’s for sensitive skin will work. Apply to the inside of the lens, let sit a bit, then buff it until clear. The same is said to work with shaving cream although I’ve yet to try either method.

Freedom To Be Uninfected

What’s to be gained from this insight into masks and their construction? In the first instance, it pays to be educated and informed when finding a mask for yourself. Over the past few months I’ve been offered the chance to buy masks from everyone from my PCB supplier through the local tool shop to my stationery provider, alongside any number of unsolicited emails. It’s a confusing marketplace with traps for the unwary that with luck will have become a little clearer.

In the next part of this series I will look at home made mask design and demonstrate how I have made masks of my own. Dust off your sewing machine, that article will be out next week.



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Keyboard Shortcuts for Calendar, Reminders, and Notes on Mac

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If you’re a Mac user looking for a simple and effective day planner, consider this trio of native macOS apps: Calendar, Reminders, and Notes.

Once you set up these apps to your liking, you have a fuss-free system to manage your schedule, tasks, and notes. Plus, if you learn how to control them with keyboard shortcuts, so much the better. And what’s more, you can discover various useful keyboard shortcuts for these macOS productivity apps in the cheat sheet below.

The cheat sheet contains shortcuts for navigation and search, view management, formatting, and more in Calendar, Reminders, and Notes.

FREE DOWNLOAD: This cheat sheet is available as a downloadable PDF from our distribution partner, TradePub. You will have to complete a short form to access it for the first time only. Download Keyboard Shortcuts for Calendar, Reminders, and Notes on Mac.

Keyboard Shortcuts for Calendar, Reminders, and Notes on Mac

Calendar
Cmd + N Add new event
Option + Cmd + N Add new calendar
Shift + Cmd + N Add new calendar group
Option + Cmd + S Add new calendar subscription
Cmd + F Highlight search box to search for events
Cmd + 1 Switch to Day view
Cmd + 2 Switch to Week view
Cmd + 3 Switch to Month view
Cmd + 4 Switch to Year view
Cmd + Right Arrow Go to next day, week, month, or year
Cmd + Left Arrow Go to previous day, week, month, or year
Cmd + T Switch to today’s date
Shift + Cmd + T Open popup for switching to specific date
Cmd + + (Plus) Increase text size
Cmd + – (Minus) Decrease text size
Cmd + R Refresh all calendars
Cmd + E Edit selected event
Esc (when event is open) Close event editor without saving changes
Return (when event is open) Commit changes to event and close event editor
Cmd + I Show Info popup for selected event(s)
¹Option + Cmd + I Show Inspector popup for selected event
Arrow Keys Select event (if available) in adjacent row/column in relevant direction
Control + Option + Up Arrow Day/Week View: Move selected event 15 minutes earlier
Month View: Move selected event one week earlier
Control + Option + Down Arrow Day/Week View: Move selected event 15 minutes later
Month View: Move selected event one week later
Control + Option + Right Arrow Day/Week/Month View: Move selected event one day later
Control + Option + Left Arrow Day/Week/Month View: Move selected event one day earlier
Shift + Cmd + A Toggle Availability panel
Reminders
Cmd + N Create new reminder
Shift + Cmd + N Create new list
²Cmd + ] Indent reminder to create subtask
²Cmd + [ Outdent reminder
Cmd + E Show all subtasks
Shift + Cmd + E Hide all subtasks
³Cmd + I Show Info popup for selected reminder
Cmd + F Highlight search box to search for reminders
²Shift + Cmd + F Set/clear flag for selected reminder(s)
Control + Cmd + S Toggle sidebar
Notes
Cmd + N Create new note
Shift + Cmd + N Create new folder
Shift + Cmd + A Open dialog for attaching file
Cmd + K Create link
Cmd + F Highlight search box to search current note
Cmd + G Highlight next search result in current note
Shift + Cmd + G Highlight previous search result in current note
Option + Cmd + F Highlight search box to search all notes
Shift + Cmd + T Apply Title format
Shift + Cmd + H Apply Heading format
Shift + Cmd + J Apply Subheading format
Shift + Cmd + B Apply Body format
Shift + Cmd + M Apply Monospaced format
Shift + Cmd + L Apply Checklist format
Shift + Cmd + U Mark selected checklist items as checked/unchecked
Control + Cmd + Up Arrow Move current list/checklist item up in list
Control + Cmd + Down Arrow Move current list/checklist item down in list
Cmd + B Emphasize selected text
Cmd + I Italicize selected text
Cmd + U Underline selected text
Cmd + + (Plus) Increase size of selected text
Cmd + – (Minus) Decrease size of selected text
Cmd + Shift + [ Align selected text flush left
Cmd + Shift + Center selected text
Cmd + Shift + ] Align selected text flush right
Cmd + [ Decrease indent level of selected content or line where cursor is placed
Cmd + ] Increase indent level of selected content or line where cursor is placed
Control + Return Add line break (soft return) to list/checklist item
Option + Tab Insert tab character in list item
Option + Cmd + C Copy style of selection
Option + Cmd + V Paste copied style to selection
Cmd + T Show Fonts window
Shift + Cmd + C Show Colors window
Option + Cmd + T Create table
⁴Return Move cursor to row below
Tab Move focus to next cell on right
Shift + Tab Move focus to next cell on left
Shift + Left/Right Arrow Select cells one by one in relevant direction current row
Shift + Up/Down Arrow Select cells one by one in relevant direction in current column
Option + Return Add new paragraph in current cell
Option + Tab Add tab character in current cell
Option + Cmd + Up Arrow Add new row above current row
Option + Cmd + Down Arrow Add new row below current row
Option + Cmd + Right Arrow Add new column to right of current column
Option + Cmd + Left Arrow Add new column to left of current column
Cmd + 0 Show main Notes window
Cmd + 1 Switch to List view for notes
Cmd + 2 Switch to Gallery view for notes
Cmd + 3 Switch to Attachments Browser
Return (when note is selected in List view or Gallery view) Open or switch focus to selected note to begin typing
Cmd + Return Open or switch focus from current note content to previous notes view i.e. List view or Gallery view
Option+ Cmd + S Toggle Folders sidebar
Shift + Cmd + . (Period) Zoom in on note content
Shift + Cmd + , (Comma) Zoom out of note content
Shift + Cmd + 0 Change note content to default size
⁵Cmd + A (When cursor is in table) Select content of active cell OR
Select table if active cell is empty
Common Shortcuts
Cmd + Z Undo previous action
Shift + Cmd + Z Reverse undo
Cmd + X Cut selected item
Cmd + C Copy selected item
Cmd + V Paste cut/copied item
Delete Delete selected item
Cmd + A Select all items
Cmd + P Open Print dialog
Cmd + , (Comma) Open app preferences
Control + Cmd + F Toggle Full Screen mode
Cmd + M Minimize window
Option + Cmd + M Minimize all windows of current app
⁶Cmd + W Close current window
Option + Cmd + W Close all windows of current app
Cmd + H Hide current app
Option + Cmd + H Hide all apps except current app
Cmd + Q Quit app
¹Shortcut does not work with multiple events, but if you switch between events when Inspector is active, its contents are updated accordingly.

²Shortcut may not be available if iCloud is not enabled.

³If multiple reminders are selected, Info popup for last selected reminder is displayed.

⁴If cursor is in last row, shortcut adds new row to table.

⁵When active cell is populated, press shortcut twice to select table.

⁶In Reminders and Notes, shortcut quits app after closing window.

Bullet Journaling With Mac Productivity Apps

The default productivity apps on macOS are not only easy to use, but also quite flexible. You can use them to bring offline note-taking methods online. For example, you can create a Bullet Journal on your Mac with Calendar, Reminders, or Notes.

Image Credit: Colton Sturgeon on Unsplash

Read the full article: Keyboard Shortcuts for Calendar, Reminders, and Notes on Mac



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If the coronavirus is really airborne, we might be fighting it the wrong way

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This was the week airborne transmission became a big deal in the public discussion about covid-19. Over 200 scientists from around the world cosigned a letter to the World Health Organization urging it to take seriously the growing evidence that the coronavirus can be transmitted through the air. WHO stopped short of redefining SARS-CoV-2 (the virus that causes covid-19) as airborne but did acknowledge that more research is “urgently needed to investigate such instances and assess their significance for transmission of COVID-19.”

“I honestly don’t know what people are waiting for,” says microbiologist Chad Roy of Tulane University in the US. “It doesn’t take WHO coming out to make a proclamation that it’s airborne for us to appreciate this is an airborne disease. I don’t know how much clearer it needs to be in terms of scientific evidence.” 

So what does “airborne” really mean in this context? It’s basically an issue of size. We’re pretty sure that SARS-CoV-2 is spread through tiny droplets that contain viral particles capable of leading to an infection. For a virus to be airborne, however, means a few different things, depending on the expert you’re talking to. Typically it means it can spread via inhalation over long distances, perhaps even through different rooms, of small particles known as aerosols.

“That’s why when you ask some of the professionals if the virus is airborne, they’ll say it’s not, because we’re not seeing transmission over those sorts of distances,” says Lisa Brosseau, a retired professor of public health who still consults for businesses and organizations.

There is also some debate on what we mean by “aerosol.” The droplets that carry viral particles through the air can come in all sorts of sizes, but while the larger ones will drop quickly to the ground or other surfaces, the smaller ones (just a few microns across) can linger in the air for a while, giving them a chance to be inhaled. The word is mostly used to describe these smaller particles, although Brosseau would prefer the term “aerosol transmission” to cover the entire gamut of inhalable viral particles being expelled into the air—large and small alike. 

If SARS-CoV-2 is airborne, it’s far from the only disease. Measles is notorious for being able to last in the air for up to two hours. Tuberculosis, though a bacterium, can be airborne for six hours, and Brosseau suggests that coronavirus superspreaders (people who seem to eject a larger amount of the virus than others) disseminate the virus in patterns that recall the infectiousness of tuberculosis.

The evidence that this type of transmission is happening with SARS-CoV-2  arguably already exists. Several big studies point to airborne transmission of the virus as a major route for the spread of covid-19. Other studies have suggested the virus can remain in aerosolized droplets for hours. One new study led by Roy and his team at Tulane shows that infectious aerosolized particles of SARS-CoV-2 could actually linger in the air for up to 16 hours, and maintain infectivity much longer than MERS and SARS-CoV-1 (the other big coronaviruses to emerge this century). 

We still don’t know what gives SARS-CoV-2 this airborne edge. “But it may be one reason this is a pandemic, and not simply a small outbreak like any other coronavirus,” says Roy. 

How to stay safe

Whether the virus is airborne isn’t simply a scientific question. If it is, it could mean that in places where the virus has not been properly contained (e.g., the US), the economy needs to be reopened more slowly, under tighter regulations that reinforce current health practices as well as introducing improved ones. Our current tactics for stopping the spread won’t be enough.

Roy would like to see aggressive mandates on strict mask use for anyone leaving home. “This virus sheds like crazy,” he says. “Masking can do an incredible amount in breaking transmission. I think anything that can promote the use of masking, to stop the production of aerosols in the environment, would be helpful.” 

Brosseau, however, says that though masks can limit the spread of larger particles, they are less helpful for smaller ones, especially if they fit only loosely. “I wish we would stop relying on the idea that face coverings are going to solve everything and help flatten the curve,” she says. “It’s magical thinking—it’s not going to happen.” For masks to really make a difference, they would need to be worn all the time, even around family.

Brosseau does believe the evidence is trending toward the conclusion that airborne transmission is “the primary and possibly most important mode of transmission for SARS-CoV-2.” She says, “I think the amount of time and effort devoted to sanitizing every single surface over and over and over again has been a huge waste of time. We don’t need to worry so much about cleaning every single surface we touch.” Instead, the focus should be on other factors, like where we spend our time.

Crowded spaces

One of the biggest questions we still have about covid-19 is how much of a viral load is needed to cause infection. The answer changes if we think it is aerosols that we need to worry about. Smaller particles won’t carry as large a viral load as bigger ones, but because they can linger in the air for much longer, it may not matter—they’ll build up in larger concentrations and get distributed more widely the longer an infected person is around to expel aerosolized virus. 

The more people you have coming in and out of an indoor space, the more likely it is that someone who is infected will show up. The longer those infected individuals spend in that space, the higher the concentration of virus in the air over time. This is particularly bad news for spaces where people congregate for hours on end, like restaurants, bars, offices, classrooms, and churches. 

Airborne transmission doesn’t necessarily mean these places must stay closed (although that would be ideal). But wiping down surfaces with disinfectant, and having everyone wear masks, won’t be enough. To safely reopen, these spots will not just need to reduce the number of people allowed inside at any given moment; they will also need to reduce the amount of time those people spend there. Increasing social distancing beyond six feet would also help keep people safer. 

Ventilation needs to be a higher priority too. This is going to be a big problem for older buildings that usually have worse ventilation systems, and areas with a lot of those might need to remain closed for much longer. The impact of asymptomatic spread (transmission by people who don’t feel ill) and superspreaders only compounds the problem even further. But research conducted by the US Department of Homeland Security has shown that in the presence of UV light, aerosolized particles of the size the Tulane researchers studied would disappear in less than a minute. A number of businesses have begun deploying UV-armed robots to disinfect hospital rooms, shopping malls, stores, public transit stations, and more.

For many places, considerable delays in economic reopening might ultimately be the price of getting the virus under control. Otherwise the kind of thing that happened when a single open bar in Michigan led to an outbreak of more than 170 new cases could become commonplace. 

For Brosseau, the best strategy is simply to behave as we did in the early days of lockdown—stay home, and avoid coming into contact with anyone you don’t live with. And if you have to leave home, she says, “all I can say is spend as little time as possible in an enclosed space, in an area that’s well ventilated, with as few people as possible.”



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Mmm… Obfuscated Shell Donuts

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In case you grow tired of clear-written, understandable code, obfuscation contests provide a nice change of scenery, and trying to make sense of their entries can be a fun-time activity and an interesting alternative to the usual brainteasers. If we ever happen to see a Simpsons episode on the subject, [Andy Sloane] has the obvious candidate for a [Hackerman Homer] entry: a rotating ASCII art donut, formatted as donut-shaped C code.

The code itself actually dates back to 2006, but has recently resurfaced on Reddit after [Lex Fridman] posted a video about it on YouTube, so we figured we take that chance to give some further attention to this nifty piece of art. [Andy]’s blog article goes in all the details of the rotation math, and how he simply uses ASCII characters with different pixel amounts to emulate the illumination. For those who prefer C over mathematical notation, we added a reformatted version after the break.

Sure, the code’s donut shape is mainly owed to the added filler comments, but let’s face it, the donut shape is just a neat little addition, and the code wouldn’t be any less impressive squeezed all in one line — or multiple lines of appropriate lengths. However, for the actual 2006 IOCCC, [Andy] took it a serious step further with his entry, and you should definitely give that one a try. For some more obfuscated shell animations, check out the fluid dynamics simulator from a few years back, and for a more recent entry, have a look at the printf Tic Tac Toe we covered last month.

int k;
double sin();
double cos();

main() {
  float A=0;
  float B=0;
  float i;
  float j;
  float z[1760];
  char  b[1760];

  printf("x1b[2J");

  for (;;) {
    memset(b, 32, 1760);
    memset(z, 0, 7040);

    for (j = 0; 6.28 > j; j += 0.07) {
      for (i = 0; 6.28 > i; i += 0.02) {
        float c = sin(i);
        float d = cos(j);
        float e = sin(A);
        float f = sin(j);
        float g = cos(A);
        float h = d + 2;
        float D = 1 / (c * h * e + f * g + 5);
        float l = cos(i);
        float m = cos(B);
        float n = sin(B);
        float t = c * h * g - f * e;

        int x = 40 + 30 * D * (l * h * m - t * n);
        int y = 12 + 15 * D * (l * h * n + t * m);
        int o = x + 80 * y;
        int N = 8 * ((f * e - c * d * g) * m - c * d * e - f * g - l * d * n);

        if (22 > y && y > 0 && x > 0 && 80 > x && D > z[o]) {
          z[o] = D;
          b[o] = ".,-~:;=!*#$@"[N > 0 ? N : 0];
        }
      }
    }

    printf("x1b[H");
    
    for (k = 0; 1761 > k; k++) {
      putchar(k % 80 ? b[k] : 10);
    }

    A += 0.04;
    B += 0.02;
  }
}

If you want to slow down (or speed up) the animation, decrease (or increase) the values added to A and B at the very end of the loop. Keep them in the same proportion to retain the rotation animation, or just play around with them and see what happens.

Remember to link against the Math library with -lm when compiling.

[via /r/programming]



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