How social distancing works, according to simple math.
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- Proper social distancing includes staying 6ft (2m) away from other people, avoiding all non-essential gatherings or crowds, and working from home if possible.
- During the COVID-19 incubation period of 5 days, each infected person can infect 2.5 more people.
- Using this math, it's easy to determine how many people will go on to be infected after the initial person contracted COVID-19 using various levels of social distancing (0%, 50% and 75% examples are found in this article).
Quarantine and isolation for COVID-19, explained
Health professionals suggest 14 days self-quarantine if you feel you may have been in contact with the virus.
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"Self-quarantine" and "flattening the curve" appear to be common phrases so far in 2020, along with hashtags on social media such as #StayHomeSaveLives and #SelfIsolation...but what does all of this truly mean?
Senior Director of Infection Prevention at Johns Hopkins (Dr. Lisa Maragakis) explains just how critical social distancing measures are when it comes to fighting the spread of the new strain of coronavirus.
What is self-quarantine?
Self-quarantine is the practice of separating yourself away from others due to the potential that you may be sick (maybe you or someone in your household has shown symptoms of COVID-19, for example).
If you feel you may have been in contact with the virus at some point, health professionals including Dr. Maragakis suggest a self-quarantine of 14 (fourteen) days minimum to determine if you will become ill and/or could be contagious to others.
During this time, you should:
- Use standard hygiene and washing hands frequently (avoid touching your face)
- Stay at home (have someone else pick up your groceries or use an order-in service)
- Not have visitors
- Refrain from sharing utensils, towels or hygiene products with others in your home
Once you have completed the minimum quarantine time and no longer show symptoms, this is when you go into "self-isolation" to ensure you do not pick up the virus somewhere and pass it along to others.
What is self-isolation?
Isolation, in medical terms, simply means keeping an infected patient away from others to avoid passing the infection.
Self-isolation in regards to COVID-19 refers to the act of isolating yourself, not specifically with doctor's orders, to avoid contracting the infection and passing it along.
"Flattening the curve" of COVID-19 refers to using protective measures to slow the spread of the infection.
The math behind social distancing: How does it help?
Scientists measure the intensity of an infectious disease by it's "reproduction number", which is the average number of people a sick person could infect.
Image by Poi NATTHAYA on Shutterstock
Social distancing is another term that has become extremely common this year. If carried out properly, social distancing really can save lives.
Proper social distancing involves:
- Keeping at least 6ft (2m) away from others at all times
- Avoiding non-essential gatherings and crowds
- Limiting contact with high-risk groups (the elderly, newborns, etc)
- Working from home if possible
- Greeting neighbors or colleagues with a wave instead of handshakes
- Avoiding going out except for when it's absolutely needed (grocery shopping, to pick up medications, etc)
With many places around the world entering "lock-down mode", gatherings including sporting events and concerts have been postponed and people who are able to work from home are being advised to do so to slow down the spread of this virus.
How does social distancing help flatten the curve?
It all comes down to the math. Scientists at Signer Laboratory in the Moores Cancer Center at the University of California San Diego measure the intensity of an infectious disease by its "reproduction number," which is the average number of people a sick person could infect.
It's important to keep a couple things in mind when explaining social distancing:
- There is a direct correlation between social exposure and the reproduction number, which the researchers call R0).
- The incubation period of COVID-19 is approximately 5 days - after this period, the person will either experience symptoms and self-quarantine or be "in the clear".
For COVID-19, the average reproduction number (R0) has been estimated at 2.5. This means that during the incubation period, each infected person can infect 2.5 more people.
Here's how the math breaks down for various levels of social distancing, from no measures taken, to 50 and 75 percent social distancing:
NO SOCIAL DISTANCING MEASURES
- Continuing your daily life as though nothing is happening
- Not practicing social distancing at all
Day 1: Person A contracts the virus
Day 5: Person A infects up to 2.5 people
Day 30: 406 people have been infected
REDUCING SOCIAL EXPOSURE - 50%
- Only leaving your house for work and to get groceries
- Practicing social distancing at work
- Not physically touching others
Day 1: Person A contracts the virus
Day 5: Person A infects up to 1.5 people
Day 30: 15 people have been infected
REDUCING SOCIAL EXPOSURE - 75%
- Self-isolation
- Only leave your home once or twice a week for the essential needs such as groceries or medical supplies
- Not having any visitors
Day 1: Person A contracts the virus
Day 5: Person A infects up to 0.625 people
Day 30: 2.5 people have been infected
Scientists and health care professionals agree on this one fundamental truth in these difficult times: social distancing can be thought of as the first line of defense against COVID-19.
"This pandemic can seem overwhelming, but in truth, every person can help slow down the spread of COVID-19. By doing your part," explains Dr. Maragakis, "you can make a big difference to your health and that of others around you."
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Image source: Sereno, et al
Mind & Brain
- A powerful MRI combined with modeling software results in a totally new view of the human cerebellum.
- The so-called 'little brain' is nearly 80% the size of the cerebral cortex when it's unfolded.
- This part of the brain is associated with a lot of things, and a new virtual map is suitably chaotic and complex.
Just under our brain's cortex and close to our brain stem sits the cerebellum, also known as the "little brain." It's an organ many animals have, and we're still learning what it does in humans. It's long been thought to be involved in sensory input and motor control, but recent studies suggests it also plays a role in a lot of other things, including emotion, thought, and pain. After all, about half of the brain's neurons reside there. But it's so small. Except it's not, according to a new study from San Diego State University (SDSU) published in PNAS (Proceedings of the National Academy of Sciences).
A neural crêpe
A new imaging study led by psychology professor and cognitive neuroscientist Martin Sereno of the SDSU MRI Imaging Center reveals that the cerebellum is actually an intricately folded organ that has a surface area equal in size to 78 percent of the cerebral cortex. Sereno, a pioneer in MRI brain imaging, collaborated with other experts from the U.K., Canada, and the Netherlands.
So what does it look like? Unfolded, the cerebellum is reminiscent of a crêpe, according to Sereno, about four inches wide and three feet long.
The team didn't physically unfold a cerebellum in their research. Instead, they worked with brain scans from a 9.4 Tesla MRI machine, and virtually unfolded and mapped the organ. Custom software was developed for the project, based on the open-source FreeSurfer app developed by Sereno and others. Their model allowed the scientists to unpack the virtual cerebellum down to each individual fold, or "folia."
Study's cross-sections of a folded cerebellum
Image source: Sereno, et al.
A complicated map
Sereno tells SDSU NewsCenter that "Until now we only had crude models of what it looked like. We now have a complete map or surface representation of the cerebellum, much like cities, counties, and states."
That map is a bit surprising, too, in that regions associated with different functions are scattered across the organ in peculiar ways, unlike the cortex where it's all pretty orderly. "You get a little chunk of the lip, next to a chunk of the shoulder or face, like jumbled puzzle pieces," says Sereno. This may have to do with the fact that when the cerebellum is folded, its elements line up differently than they do when the organ is unfolded.
It seems the folded structure of the cerebellum is a configuration that facilitates access to information coming from places all over the body. Sereno says, "Now that we have the first high resolution base map of the human cerebellum, there are many possibilities for researchers to start filling in what is certain to be a complex quilt of inputs, from many different parts of the cerebral cortex in more detail than ever before."
This makes sense if the cerebellum is involved in highly complex, advanced cognitive functions, such as handling language or performing abstract reasoning as scientists suspect. "When you think of the cognition required to write a scientific paper or explain a concept," says Sereno, "you have to pull in information from many different sources. And that's just how the cerebellum is set up."
Bigger and bigger
The study also suggests that the large size of their virtual human cerebellum is likely to be related to the sheer number of tasks with which the organ is involved in the complex human brain. The macaque cerebellum that the team analyzed, for example, amounts to just 30 percent the size of the animal's cortex.
"The fact that [the cerebellum] has such a large surface area speaks to the evolution of distinctively human behaviors and cognition," says Sereno. "It has expanded so much that the folding patterns are very complex."
As the study says, "Rather than coordinating sensory signals to execute expert physical movements, parts of the cerebellum may have been extended in humans to help coordinate fictive 'conceptual movements,' such as rapidly mentally rearranging a movement plan — or, in the fullness of time, perhaps even a mathematical equation."
Sereno concludes, "The 'little brain' is quite the jack of all trades. Mapping the cerebellum will be an interesting new frontier for the next decade."
