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Measuring mass in the metric system
In science and engineering we often have to make measurements of mass. Now, I understand that a lot of American students have affinity for the traditional English system of measurements.
But we can’t make much progress in any field of science or engineering without first becoming conversant with the metric system. It is used worldwide.
How do we measure mass? To learn practical, hands-on skills, see our lesson here.
Measuring mass with a triple beam balance
But in this lesson we’re going to get a feel what various masses would actually look like in real life.
Kilograms
A kilogram is 1,000 grams. It is abbreviated as kg.
Can we convert between kilograms and pounds…. not quite [TBA]
But if all measurements are done here on Earth then 1 kg of mass has a weight of about 2.2 pounds.
Here’s a 1 kg steak dinner
image from TripAdvisor, Outback Steakhouse, Las Vegas Blvd
How can we visualize this? About the mass of a liter bottle of water or soda.
About the mass of good size hardcover book. About the mass of a quart of Gatorade.
Or about the mass of an adult Black-Footed Ferret.
Grams
A metric unit of mass is the gram abbreviated as g.
What kind of things are about a gram in mass?
Centigrams
Centi means 1/100th 0.01 10-2
A smaller metric unit of mass is the centigram abbreviated as cg.
It is one one-hundredth of a gram.
What kind of things are about a cg in mass? Many medications come in 1 cg size, although they more often are measured as 100 mg. Here are magnesium supplement pills.
When a pencil tip breaks, a bigger piece could be about 1 cg.
(We could name something that has a mass of gram and divide it in ten pieces)
milligrams
milli means 1/1000th 0.001 10-3
This is 1/1000th of a gram.
What kind of things are commonly measured in milligrams?
Many doses of medications are measured in milligrams:
Amitriptyline (Elavil) treats chronic pain and depression.
Atorvastatin (Lipitor) treats high cholesterol.
Amlodipine (Norvasc) treats high blood pressure and angina.
Here is crushed powder of a medication shown next to a penny for comparison.
Penny, 1 mg, 10 mg, 25 mg
Micrograms
Yet even smaller is the microgram abbreviated as μg
micro means 1/1,000,000th 0.000001 10-6
Just one one-millionth of a gram
What kind of things are commonly measured in micrograms?
Grains of sand are around 30 to 50 micrograms.
Mass of a grain of sand
Nanograms
Abbreviated as ng.
nano means 1/1,000,000,000 th 0.000000001 10-9
Imagine cutting a raisin into a billion pieces. Each of those tiny pieces has a mass of about one ng.
What kind of things are about a nanogram in mass?
A human cell or a grain of birch pollen. Note that in this picture, each dot that you can see is likely dozens of pollen grains stuck together.
Each individual grain by itself is so small that you’d need a microscope to clearly see it.
Nanograms are very small compared to anything we see in our daily lives, but they are large compared to a single atom
Chemistry math & mass problem
How many atoms of iron (Fe) are in 1 ng (1.0 x 10-9 g) of iron?
This problem from xaktly – Chemistry – The Mole.
We start by finding the molar mass of iron from the periodic table. It’s 55.85 g/mol.
We use the molar mass to convert to moles.
Then multiply by 6.022 x 1023 atoms per mole to get the number of atoms.
1 ng of iron atoms is about 1 x 10 ^ 13 atoms!
That’s 10,000,000,000,000 atoms.
Videos
Powers of Ten and the Relative Size of Things in the Universe
Thanks for reading. While you’re here see our other articles on astronomy, biology, chemistry, Earth science, mathematics, physics, the scientific method, and making science connections through books, TV and movies.
Computer apps
Powers of Ten (JAVA) For Windows and Macs. Check to see if this runs on Android phones or Chromebooks.
Secret Worlds: The Universe Within: Molecular Expressions
The size and scale of the universe
htwins.net – scale of the universe
Smartphone and tablet apps
Cosmic Zoom app by Tokata. For Android and iPad
Google Play Store link
About cozmic zoom
Powers of Minus Ten, by Dynamoid Apps. iPad app
thepartnershipineducation.com Powers-of-minus-ten
Link for the Apple app store
Learning Standards
Massachusetts Science and Technology/Engineering Curriculum Framework
Science and Engineering Practices: 5. Using Mathematics and Computational Thinking: Apply ratios, rates, percentages, and unit conversions in the context of complicated measurement problems involving quantities with derived or compound units (such as mg/mL, kg/m 3, acre-feet, etc.).
National Council of Teachers of Mathematics
Students need to develop an understanding of metric units and their relationships, as well as fluency in applying the metric system to real-world situations. Because some non-metric units of measure are common in particular contexts, students need to develop familiarity with multiple systems of measure, including metric and customary systems and their relationships.
National Science Teachers Association
The efficiency and effectiveness of the metric system has long been evident to scientists, engineers, and educators. Because the metric system is used in all industrial nations except the United States, it is the position of the National Science Teachers Association that the International System of Units (SI) and its language be incorporated as an integral part of the education of children at all levels of their schooling.
Busting myths: No Virginia, some sugars aren’t better than others
Myth “Some sugars are better for our bodies than others.”
Myth “Natural, raw or unrefined sugars are better.”
Myth “It is better to use honey, maple syrup, agave syrup, or coconut sugar.”
Myth “Corn syrup is worse for us than other sugars”
Myth “Natural sugar is better than processed sugar.”
Reality: None of those claims are really true. In reality our metabolism breaks down all sugars the same way.
Agave syrup, maple syrup, coconut sugar – none of these are sugar alternatives – they are just sources of sugar.
Sucrose, a common sugar, is a disaccharide. That means it is a two-part molecule, made of glucose and fructose.
And get this – sucrose is not absorbed by the human GI tract. Instead, our intestines secrete an enzyme, sucrase-isomaltase.
This breaks down any sucrose into glucose and fructose, and it is those smaller sugars which are absorbed. So our body doesn’t care which kind of sugar we eat; the result is the same.
Image from sucraid.com/about-csid
Myth “Natural sugar is better than processed sugar.”
All sugars are processed. The so-called “processed” white sugar that people are afraid of is just sugar from a natural source, sugar cane or beets. Brown sugar? The same as white sugar, except that the molasses hasn’t been removed. Not healthier whatsoever.
“Raw honey” may be unprocessed, but it isn’t any healthier. It is just sugar mixed with water, pollen and a few other organic molecules. You’re not going to be helped by the microscopic amount of nutrients in raw honey unless you ate pounds of it a day.
Myth “High fructose corn syrup is worse for you than other sugar.”
Reality? Nope. It’s literally the same thing.
image from Examine.com, difference between HFCS and sugar
More details on this bit here – What is the difference between high fructose corn syrup (HFCS) and sugar?
Myth “Sugars higher on the glycemic index are worse for you.”
Nope. Such claims come from flawed studies, see below for details.
So, are we saying that sugar is good for you? No, we aren’t saying that either. Mainstream science already knows the answer, and people just refuse to hear it: For most people, having some sugar in our diet has always been fine. The problem comes from diets which have huge amounts of sugar, and not enough of other foods that actually are good for us.
While no one, single diet is best for everyone, science points to the same direction: Eat a balanced diet with whole grains, beans, legumes, vegetables and fruit. Have less meat, and certainly less processed meat. Eat far less fried foods. Watch your total calorie intake. Keep daily sugar and fat intake lower. There you go.
What’s wrong with those glucose versus sucrose studies?
In those studies, researchers did the following: They fed huge amounts of only one type of sugar molecule to one group of rats, and huge amounts of a different type of sugar molecule to another group of rats. Then they looked at how the health of the rats were affected over time.
Problem 1: These studies don’t resemble real world eating. Humans don’t spend entire days eating nothing but fructose or nothing but sucrose. The way that our metabolism would handle that is different from how it would handle normal eating, in which sugar is only a small part of the diet. In real life, even in poor diets, sugar is still only a fraction of the total: there are also proteins, complex carbohydrates, fats, oils, vitamins, minerals, etc.
Problem 2: Some studies attempted to see how consuming different sugars affects one’s resulting blood sugar level. Sugar molecules which create a higher result are said to be higher on a glycemic index; sugar molecules which create a lower result are said to be lower on the glycemic index. Yet these are unnatural diets in which rats ate only pure sugars. When we study the results of normal diets, with actual food, there’s almost no difference between sugars. A meal’s impact on resulting blood sugar levels depends on the amount of sugar and how fast it gets absorbed, not on the type of sugar molecule.
Problem 3: Rats do not metabolize sugars in the same ways that humans do. Hence, any inaccuracies due to the above problems become magnified, making the results non applicable to humans.
Result: The data from those studies are essentially useless.
Honors biology details
Glucose enters the glycolysis metabolic pathway at the top.
Here it is phosphorylated by Hexokinase.
Fructose enters glycolysis pathway two steps later, where it meets phosphofructokinase.
Thus, eating pure fructose allows the energy to be metabolized a bit faster than eating pure glucose.
But people don’t consume huge chunks of pure sugars. When eating anything resembling real life meals, the difference is very little.
Studies on High-fructose corn syrup (HFCS)
High-fructose corn syrup (HFCS) is also known as glucose-fructose, isoglucose and glucose-fructose syrup. There is no scientific evidence that HFCS itself causes obesity or metabolic syndrome, but rather overconsumption and excessive caloric intake of any sweetened food or beverage may contribute to these diseases.
Epidemiological research has shown that the increase in metabolic disorders, such as obesity and non-alcoholic fatty liver disease, is linked to increased consumption of sugars and calories in general.
A 2012 review found that fructose did not appear to cause weight gain when it replaced other carbohydrates in diets with similar calories.
A 2014 systematic review found little evidence for an association between HFCS consumption and liver diseases, enzyme levels or fat content.
The American Heart Association recommended that people limit added sugar (such as maltose, sucrose, high fructose corn syrup, molasses or cane sugar) in their diets.
High fructose corn syrup article
Is Sugar Really Toxic? Sifting through the Evidence
Scientific American Staff and Ferris Jabr, Scientific American, July 15, 2013
https://blogs.scientificamerican.com/brainwaves/is-sugar-really-toxic-sifting-through-the-evidence/
By consuming so much sugar we are not just demonstrating weak willpower and indulging our sweet tooth – we are in fact poisoning ourselves according to a group of doctors, nutritionists and biologists, one of the most prominent members of which is Robert Lustig of the University of California, San Francisco…
A few journalists, such as Gary Taubes and Mark Bittman, have reached similar conclusions. Sugar, they argue, poses far greater dangers than cavities and love handles; it is a toxin that harms our organs and disrupts the body’s usual hormonal cycles.
Excessive consumption of sugar, they say, is one of the primary causes of the obesity epidemic and metabolic disorders like diabetes, as well as a culprit of cardiovascular disease. More than one-third of American adults and approximately 12.5 million children and adolescents in the U.S. are obese. In 1980, 5.6 million Americans were diagnosed with diabetes; in 2011 more than 20 million Americans had the illness.
…. Because fructose metabolism seems to kick off a chain reaction of potentially harmful chemical changes inside the body, Lustig, Taubes and others have singled out fructose as the rotten apple of the sugar family. When they talk about sugar as a toxin, they mean fructose specifically.
In the last few years, however, prominent biochemists and nutrition experts have challenged the idea that fructose is a threat to our health and have argued that replacing fructose with glucose or other sugars would solve nothing.
First, as fructose expert John White points out, fructose consumption has been declining for more than a decade, but rates of obesity continued to rise during the same period. Of course, coinciding trends alone do not definitively demonstrate anything.
A more compelling criticism is that concern about fructose is based primarily on studies in which rodents and people consumed huge amounts of the molecule – up to 300 grams of fructose each day, which is nearly equivalent to the total sugar in eight cans of Coke – or a diet in which the vast majority of sugars were pure fructose. The reality is that most people consume far less fructose than used in such studies and rarely eat fructose without glucose.
…. Not only do many worrying fructose studies use unrealistic doses of the sugar unaccompanied by glucose, it also turns out that the rodents researchers have studied metabolize fructose in a very different way than people do—far more different than originally anticipated.
… Even if Lustig is wrong to call fructose poisonous and saddle it with all the blame for obesity and diabetes, his most fundamental directive is sound: eat less sugar. Why? Because super sugary, energy-dense foods with little nutritional value are one of the main ways we consume more calories than we need, albeit not the only way.
Glycemic index and obesity
Janette C Brand-Miller, Susanna HA Holt, Dorota B Pawlak, Joanna McMillan
Glycemic index and obesity, The American Journal of Clinical Nutrition
Volume 76, Issue 1, July 2002, Pages 281S–285S
https://doi.org/10.1093/ajcn/76.1.281S
Although weight loss can be achieved by any means of energy restriction, current dietary guidelines have not prevented weight regain or population-level increases in obesity and overweight. Many high-carbohydrate, low-fat diets may be counterproductive to weight control because they markedly increase postprandial hyperglycemia and hyperinsulinemia.
Many high-carbohydrate foods common to Western diets produce a high glycemic response [high-glycemic-index (GI) foods], promoting postprandial carbohydrate oxidation at the expense of fat oxidation, thus altering fuel partitioning in a way that may be conducive to body fat gain.
In contrast, diets based on low-fat foods that produce a low glycemic response (low-GI foods) may enhance weight control because they promote satiety, minimize postprandial insulin secretion, and maintain insulin sensitivity.
This hypothesis is supported by several intervention studies in humans in which energy-restricted diets based on low-GI foods produced greater weight loss than did equivalent diets based on high-GI foods.
Long-term studies in animal models have also shown that diets based on high-GI starches promote weight gain, visceral adiposity, and higher concentrations of lipogenic enzymes than do isoenergetic, macronutrient controlled, low-GI-starch diets.
In a study of healthy pregnant women, a high-GI diet was associated with greater weight at term than was a nutrient-balanced, low-GI diet.
In a study of diet and complications of type 1 diabetes, the GI of the overall diet was an independent predictor of waist circumference in men.
These findings provide the scientific rationale to justify randomized, controlled, multicenter intervention studies comparing the effects of conventional and low-GI diets on weight control.
Straight talk about high-fructose corn syrup: what it is and what it ain’t,
Straight talk about high-fructose corn syrup: what it is and what it ain’t,
John S. White, The American Journal of Clinical Nutrition
Volume 88, Issue 6, December 2008, Pages 1716S–1721S, https://doi.org/10.3945/ajcn.2008.25825B
High-fructose corn syrup (HFCS) is a fructose-glucose liquid sweetener alternative to sucrose (common table sugar) first introduced to the food and beverage industry in the 1970s. It is not meaningfully different in composition or metabolism from other fructose-glucose sweeteners like sucrose, honey, and fruit juice concentrates.
HFCS was widely embraced by food formulators, and its use grew between the mid-1970s and mid-1990s, principally as a replacement for sucrose. This was primarily because of its sweetness comparable with that of sucrose, improved stability and functionality, and ease of use.
Although HFCS use today is nearly equivalent to sucrose use in the United States, we live in a decidedly sucrose-sweetened world: >90% of the nutritive sweetener used worldwide is sucrose. Here I review the history, composition, availability, and characteristics of HFCS in a factual manner to clarify common misunderstandings that have been a source of confusion to health professionals and the general public alike.
In particular, I evaluate the strength of the popular hypothesis that HFCS is uniquely responsible for obesity. Although examples of pure fructose causing metabolic upset at high concentrations abound, especially when fed as the sole carbohydrate source, there is no evidence that the common fructose-glucose sweeteners do the same.
Thus, studies using extreme carbohydrate diets may be useful for probing biochemical pathways, but they have no relevance to the human diet or to current consumption. I conclude that the HFCS-obesity hypothesis is supported neither in the United States nor worldwide.
Thanks for reading. While you’re here see our other articles on astronomy, biology, chemistry, Earth science, mathematics, physics, the scientific method, and making science connections through books, TV and movies.
Plant identification apps
Learning objectives
SWBAT (“students will be able to,” content, procedures, skills)
Describe characteristics of seeds and plants, based on observation.
Identify characteristics that are the same or different across various seeds and plants.
Use a dichotomous key
Vocabulary objectives
Tier II: Classify, Differentiate, Analyze
Tier III: Dichotomous key, bryophytes, vascular, seed, confiers, angiosperms, gymnosperms, monocotsm dicots
Connections
Life is classified in kingdoms; that plants are one of the many kingdoms; that this kingdom itself is broken down into many smaller groups. Students should be able to recognize what a plant looks like, and have the prior knowledge that plants need sunlight, space and water to survive.
Why identify plants?
Students should be able to explain several ways that plants are useful.
Answers might include:
Large scale food production
Local, community and home food production
Managing national and state parks
Necessary for a healthy ecosystem (biodiversity)
Necessary for human psychological health (contrast blighted areas with plant, tree and flower-rich yards.)
Biology, Miller and Levine, Chap 4, Pearson.
Use of plants in managing wildlife
From Noble News and Views:
“As natural resource managers, we must understand what we manage, and plant identification is a key component of that understanding.”
“whether you are a cow-calf producer, sheep and goat producer, wildlife manager, or manager of some combination of these enterprises, you should be paying close attention to what your management decisions are doing to the resources that support your enterprises: plants. After all, plants are what produce these products.”
“The ability to know, or identify, plants allows us to assess many important rangeland or pasture variables that are critical to proper management: range condition, proper stocking rates, forage production, wildlife habitat quality, and rangeland trend, either upward or downward.”
Noble.org – Plant-identification-is-it-worth-the-effort
Why use dichotomous keys?
Students often learn how to identify plants with dichotomous keys. This is a math and logic skill, valuable for classifying all forms of life (and any kind of classification system.)
A dichotomy is a partition of a whole (or a set) into two parts. This is an essential part of mathematical logic
The use of a dichotomous key for identification is an algorithm.
Apps
iNaturalist – https://www.inaturalist.org/
“Naturalist helps you identify the plants and animals around you. Get connected with a community of over 400,000 scientists and naturalists who can help you learn more about nature!”
PictureThis – https://www.picturethisai.com/
Helps more than 30,000,000 users identify, learn, and enjoy all kinds of plants: flowers, trees, succulents, cacti and more! Capable of identifying 10,000+ plant species.
Plantix – https://plantix.net/en/
Are you a farmer or hobby gardener and grow vegetables, fruit or arable crops? Are your plants sick; did you have losses in the last harvest? We are Plantix and offer you fast and free help. Whether you grow tomatoes, bananas or rice – Plantix is your interactive plant doctor. “
PlantNet Plant Identification https://plantnet.org/en/
This is a research and a citizen science project. Works on more than 20,000 wild plants, and ornamental and cultivated plants
Google Lens https://lens.google.com/
An image recognition technology developed by Google. Brings up relevant info about objects that it identifies using visual analysis based on a neural network.
External resources
Classification and dichotomous key worksheet
Using Dichotomous Keys Middle School Scientists Curriculum
BioNinja Dichotomous Keys
Cultural and religious importance of plants
Many different cultures and religions have specific uses for particular plants. Certain plants may be used in various holidays or ritual observances.
One of the goals of Social Studies is to expose students to the diversity of ethnic, religious, and cultural observances in our world.
The College, Career, and Civic Life (C3) Framework for Social Studies State Standards notes that students should be able to describe how religions are embedded in culture and cannot only be isolated to the “private” sphere, and identify which religious communities are represented or obscured in public discourse.
Thus, science and social studies teachers can work together to create multi-disciplinary units.
Ethnobotany
The study of a region’s plants and their practical uses through the traditional knowledge of a local culture and people. An ethnobotanist studies local customs involving uses of local flora for many aspects of life, such as plants as medicines, foods, intoxicants and clothing.
Ethnobotany, US Forest Service
Plants in the Jewish tradition
The Sabbath year (shmita; Hebrew: שמיטה, literally “release”), also called the Sabbatical year or Shevi’it (שביעית, literally “seventh”.) This is the seventh year of the seven-year agricultural cycle mandated by the Torah for agriculture by Jewish people living in Israel. During this year the land is left to lie fallow, allowing the soil to regenerate nutrients. With certain exceptions, most agricultural activity is not allowed during this year.
Genesis – Shmitah year covenant, Neohasid.org
What is shmita? My Jewish Learning
Lulav and Etrog, the four species Wikipedia
Trees in Jewish Thought
The Seven Species of plants in the land of Israel.
Plants in the Christian tradition
Trees and plants in the Christian tradition
Trees and religion: Christianity
Plants in the Islamic tradition
Islamic garden
Environmental protection – Islamic shariah
Plants in Buddhist tradition
Ecological significance of plants in Buddhism
Plants in Native American traditions
Native American ethnobotany
Native American Plant Use
Plants in Hinduism
Trees and religion: Hinduism
Plants of religious significance
Thanks for reading. While you’re here see our other articles on astronomy, biology, chemistry, Earth science, mathematics, physics, the scientific method, and making science connections through books, TV and movies.
Learning Standards
Common Core ELA CCSS.ELA-LITERACY.RST.9-10.3
Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.
Next Generation Science Standards
2-LS4-1. Make observations of plants and animals to compare the diversity of life in different habitats.
2-PS1-1. Plan and conduct an investigation to describe and classify different kinds of materials by their observable properties.
MS-LS4-2. Apply scientific ideas to construct an explanation for the anatomical similarities and differences among modern organisms and between modern and fossil organisms to infer evolutionary relationships.
National Science Education Standards, The National Academies Press, 1996
Biological classifications are based on how organisms are related. Organisms are classified into a hierarchy of groups and subgroups based on similarities which reflect their evolutionary relationships. Species is the most fundamental unit of classification.
[Use of dichotomous key is a math skill] – Use Math in all aspects of scientific inquiry: Mathematics is essential to asking and answering questions about the natural world. Mathematics can be used to ask questions; to gather, organize, and present data; and to structure convincing explanations.
Benchmarks for Science Literacy
American Association for the Advancement of Science
Students should begin to extend their attention from external anatomy to internal structures and functions. Patterns of development may be brought in to further illustrate similarities and differences among organisms. Also, they should move from their invented classification systems to those used in modern biology…
A classification system is a framework created by scientists for describing the vast diversity of organisms, indicating the degree of relatedness between organisms, and framing research questions.
SAT Biology Subject Area Test
Evolution and diversity: Origin of life, evidence of evolution, patterns of evolution, natural selection, speciation, classification and diversity of organisms.
Teaching About Evolution and the Nature of Science (National Academy Press)
Biological classifications are based on how organisms are related. Organisms are classified into a hierarchy of groups and subgroups based on similarities which reflect their evolutionary relationships. Species is the most fundamental unit of classification.
Massachusetts Digital Literacy and Computer Science (DLCS) Curriculum Framework
Use of Dichotomous key for identification is an algorithm:
Algorithms [3-5.CT.b]
1. Define an algorithm as a sequence of instructions that can be processed by a computer.
2. Recognize that different solutions exist for the same problem (or sub-problem).
3. Use logical reasoning to predict outcomes of an algorithm.
National Curriculum Standards for Social Studies
3. People, Places, and Environments
The study of people, places, and environments enables us to understand the relationship between human populations and the physical world. Students learn where people and places are located and why they are there. They examine the influence of physical systems, such as climate, weather and seasons, and natural resources, such as land and water, on human populations….
During their studies, learners develop an understanding of spatial perspectives, and examine changes in the relationship between peoples, places and environments….
Immunosenescence (aging of immune system)
Introduction
(In this GIF we see Y-shaped antibodies recognizing and attaching to a pathogen, targeting it for destruction.)
Ed Yong writes, there’s a joke about immunology, which Jessica Metcalf of Princeton recently told me:
An immunologist and a cardiologist are kidnapped. The kidnappers threaten to shoot one of them, but promise to spare whoever has made the greater contribution to humanity. The cardiologist says, “Well, I’ve identified drugs that have saved the lives of millions of people.” Impressed, the kidnappers turn to the immunologist. “What have you done?” they ask. The immunologist says, “The thing is, the immune system is very complicated …” And the cardiologist says, “Just shoot me now.”
Immunology Is Where Intuition Goes to Die, The Atlantic
________________________________
Immunosenescence refers to the gradual deterioration of the immune system brought on by natural age advancement.
The adaptive immune system is affected more than the innate immune system. [1]
It deteriorates
* our capacity to respond to infections
* the development of long-term immune memory, especially by vaccination. [2]
This age-associated immune deficiency is ubiquitous. It is found in both long- and short-living species as a function of their age relative to life expectancy rather than chronological time. [3]
It is considered a major contributory factor to the increased frequency of morbidity and mortality among the elderly.
Immunosenescence is not random. It appears to repeat an evolutionary pattern. Most of the parameters affected by immunosenescence appear to be under genetic control. [4]
It is the result of increasing, lifelong exposures to a variety of antigens such as viruses and bacteria. [5]
{This introduction has been adapted from the Wikipedia article, Immunosenescence}
How it works
New medical techniques to fight against Immunosenescence
COVID-19 poses the greatest threat to older people, but vaccines often don’t work well in this group. Scientists hope drugs that rejuvenate the immune system will help.
The text below has been excerpted from How anti-ageing drugs could boost COVID vaccines in older people, Cassandra Willyard, Nature (news feature) 10/14/2020
Immunosenescence explains why older age groups are so hard-hit by COVID-19 [and why] vaccines, which incite the immune system to fight off invaders, often perform poorly in older people. The best strategy for quelling the pandemic might fail in exactly the group that needs it most.
[With aging] some types of immune cell become depleted: for example, older adults have fewer naive T cells that respond to new invaders, and fewer B cells, which produce antibodies that latch on to invading pathogens and target them for destruction.
[With aging] older people also tend to experience chronic, low-grade inflammation [inflammageing.] This constant buzz of internal activation makes the immune system less responsive to external insults.
With many COVID-19 vaccine candidates currently being tested… researchers say it’s not yet clear how they will fare in older adults.
… If COVID-19 vaccines perform less well in older adults, researchers might be able to find ways to tweak the shot itself to elicit a stronger response. Some influenza vaccines, for instance, include immune-boosting ingredients or higher doses of the viral antigen.
But some scientists say there is a better option. They are developing and testing drugs that could improve how older adults respond to vaccines and might also help them fight viruses more effectively in the first place. Rather than working with the limitations of the ageing immune system, they are planning to rejuvenate it.
… One promising class of anti-ageing drug acts on pathways involved in cell growth. These drugs inhibit a protein known as mTOR. In the laboratory, inhibiting mTOR lengthens lifespan in animals from fruit flies to mice.
….The type 2 diabetes drug metformin also dampens down mTOR’s activity, albeit indirectly. Some studies suggest that people who take metformin are less likely to be hospitalized or die if they contract COVID-19.
…diseases such as diabetes and obesity lead to some of the same immune deficits as occur in older age.
… many anti-ageing pathways seem to be linked, says James Kirkland, who studies cellular ageing and disease at the Mayo Clinic in Rochester, Minnesota.
“That is, if you target one, you tend to affect all the rest,” he says. Many of the immune changes that come with ageing lead to the same result: inflammation. So researchers are looking at drugs that will calm this symptom.
… Another class of drug, called senolytics, helps to purge the body of cells that have stopped dividing but won’t die.
_____________________________
Thanks for reading. While you’re here see our other articles on astronomy, biology, chemistry, Earth science, mathematics, physics, the scientific method, and making science connections through books, TV and movies.
Learning Standards
Next Generation Science Standards (NGSS)
HS-LS1-2 Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.
DCI – LS1.A: Structure and Function – Feedback mechanisms maintain a living system’s internal conditions within certain limits and mediate behaviors, allowing it to remain alive and functional even as external conditions change within some range.
Evidence statements: In the model, students describe the relationships between components, including:
* A system’s function and how that relates both to the system’s parts and to the overall function of the organism.
* Students use the model to illustrate how the interaction between systems provides specific functions in multicellular organisms
Massachusetts Comprehensive Health Curriculum Framework
Students will gain the knowledge and skills to select a diet that supports
health and reduces the risk of illness and future chronic diseases. PreK–12 Standard 4
8.1 Describe how the body fights germs and disease naturally and with medicines and
immunization
8.2 Identify the common symptoms of illness and recognize that being responsible for individual health means alerting caretakers to any symptoms of illness.
8.5 Identify ways individuals can reduce risk factors related to communicable and chronic diseases
8.6 Describe the importance of early detection in preventing the progression of disease.
8.7 Explain the need to follow prescribed health care procedures given by parents and health care providers.
8.8 Describe how to demonstrate safe care and concern toward ill and disabled persons in the family, school, and community.
8.13 Explain how the immune system functions to prevent and combat disease
Interdisciplinary Learning Objectives: Disease Prevention and Control
8.a. (Law & Policy. Connects with History & Social Science: Geography and Civics & Government) Analyze the influence of factors (such as social and economic) on the treatment and management of illness.
Benchmarks for Science Literacy, AAAS
The immune system functions to protect against microscopic organisms and foreign substances that enter from outside the body and against some cancer cells that arise within. 6C/H1*
Some allergic reactions are caused by the body’s immune responses to usually harmless environmental substances. Sometimes the immune system may attack some of the body’s own cells. 6E/H1
Some viral diseases, such as AIDS, destroy critical cells of the immune system, leaving the body unable to deal with multiple infection agents and cancerous cells. 6E/H4
Vaccines induce the body to build immunity to a disease without actually causing the disease itself. 6E/M7** (BSL)
Footnotes
1 Pangrazzi L, Weinberger B (2020). “T cells, aging and senescence”. Experimental Gerontology. 134: 110887. doi:10.1016/j.exger.2020.110887. PMID 32092501. S2CID 211237913.
2. Muszkat, M; E. Greenbaum; A. Ben-Yehuda; M. Oster; E. Yeu’l; S. Heimann; R. Levy; G. Friedman; Z. Zakay-Rones (2003). “Local and systemic immune response in nursing-home elderly following intranasal or intramuscular immunization with inactivated influenza vaccine”. Vaccine. 21(11–12): 1180–1186. doi:10.1016/S0264-410X(02)00481-4. PMID 12559796.
3. Ginaldi, L.; M.F. Loreto; M.P. Corsi; M. Modesti; M. de Martinis (2001). “Immunosenescence and infectious diseases”. Microbes and Infection. 3 (10): 851–857. doi:10.1016/S1286-4579(01)01443-5. PMID 11580980.
4. Franceschi, C.; S. Valensin; F. Fagnoni; C. Barbi; M. Bonafe (1999). “Biomarkers of immunosenescence within an evolutionary perspective: the challenge of heterogeneity and the role of antigenic load”. Experimental Gerontology. 34 (8): 911–921. doi:10.1016/S0531-5565(99)00068-6. PMID 10673145. S2CID 32614875.
5. Franceschi, C.; M. Bonafè; S. Valensin (2000). “Human immunosenescence: the prevailing of innate immunity, the failing of clonotypic immunity, and the filling of immunological space”. Vaccine. 18 (16): 1717–1720. doi:10.1016/S0264-410X(99)00513-7. PMID 10689155.
Use Statement
This website is educational. Materials within it are being used in accord with the Fair Use doctrine, as defined by United States law.
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Unmasking mask myths
We are living in an era of a viral pandemic, COVID-19, in which viral particles are spread through the air from one person to another.
Numerous scientific studies show that if most people even simple cloth face masks while near each other, this dramatically reduced the viral particles in the air, and increases safety.
The effect of wearing masks is so effective that in areas where people follow social distancing & mask rules, the incidence of COVID is shrinking.
However, there has been a growing resistance to wearing a mask, fueled by conspiracy theories, pseudoscience, and Russian social media troll farms deliberately spreading misinformation.
Many of us have met individuals who claimed that face masks either “block oxygen from getting in” or “make us breathe carbon monoxide.” Both claims are literally impossible, yet widely believed.
If we have a student make such a claim, how can we turn this into a teachable moment?
https://www.facebook.com/groups/907893332705087/permalink/1547682505392830/
Addressing the carbon monoxide claim
Claim: “Masks traps our carbon monoxide and poison us.”
How to respond:
First, revisit the equation for cellular respiration. Note that this process doesn’t produce carbon monoxide!
from the Amoeba sisters
So if someone makes this claim then ask “Where does this carbon monoxide coming from?”
If they give a vague response ask them to clarify and back up their answer with a source.
Here’s another graphic showing cellular respiration
Addressing the “air can’t get through the mask” claim
Some people try to have it both ways: They claim that virus particles are so small that they can get through the mask
yet they also claim that the oxygen is too large to pass through the mask, so we (supposedly) get low oxygen and brain damage.
The obvious problem is that the virus particle is over 250 times larger than an oxygen molecule!
The covid molecule is 0.125 microns while an O2 molecule is only 0.0005 microns.
Also, to be clear, single viral particles don’t make people sick. The disease is only spread if people inhale multiple exhalation water-virus droplets,
Each droplet is thousands of times larger than a viral particle; each droplet has thousands of viral particles. It is these larger drops that masks are good at filtering.
Image created by Fusion Animation.
Addressing the low amount of oxygen claim
First off, even without a virus, your body automatically adapts to lower levels of oxygen in the air.
If that weren’t the case then anyone who visited a high altitude city like Denver, Colorado, would have died.
As we all know, up in Denver the air is thinner, so there are less O2 molecules per cubic meter of air. But we adjust, and as long as we don’t play NFL caliber football for an hour, we’re just fine.
The other claim is that these face masks “trap our breath” preventing us from getting oxygen, so that our O2 blood levels fall.
Yet see for yourself – masks don’t do that!
Photo credit. Dr. Megan Hall
Dr. Megan Hall writes:
Below is me in 4 scenarios. I wore each mask for 5 minutes and checked my oxygen saturation (shown as the percentage below) along with my heart rate (HR, in beats per minute) using noninvasive pulse oximetry.
Keep in mind, immediately prior to this, I had been wearing the surgical mask for 5 hours.
Results:
No mask: 98%, HR 64
Surgical mask: 98%, HR 68
N95 mask: 99%, HR 69
N95 plus surgical mask (which is how most healthcare providers are wearing masks): 99%, HR 69.
Finally, if “breathing in your own breath is dangerous” then
* how come it is perfectly safe to perform CPR with mouth to mouth resuscitation?
* how come it is safe to kiss?!
The air that a person exhales has more than enough O2 to keep someone else alive.
How well do masks work?
Masks don’t need to stop all droplets. COVID is dangerous not because some particles are airborne (thats true for tons of viruses) but because
(a) it transmits more easily,
and (b) causes more damage.
When we reduce the number of droplets released, then the spread of covid significantly decreases.
Here is a video from Dr. Joe Hanson, from “It’s ok to be smart.” It is an awesome, slow-motion schlieren imaging experiment that demonstrates why masks work.
How Well Do Masks Work? (Schlieren Imaging In Slow Motion!)
References for “How Well Do Masks Work?”
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We’re not using umbrellas as they were originally intended – https://qz.com/quartzy/1707271/americans-are-not-using-umbrellas-as-they-were-intended/
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World Health Organization – Q&A about masks https://www.who.int/emergencies/diseases/novel-coronavirus-2019/question-and-answers-hub/q-a-detail/q-a-on-covid-19-and-masks
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American Society for Microbiology – COVID-19 Transmission Dynamics
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Oran, Daniel P., and Eric J. Topol. “Prevalence of Asymptomatic SARS-CoV-2 Infection: A Narrative Review.” Annals of Internal Medicine (2020). https://doi.org/10.7326/M20-3012
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Chu, Derek K., et al. “Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis.” The Lancet (2020). https://doi.org/10.1016/S0140-6736(20)31142-9
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Dhama, Kuldeep, et al. “Coronavirus disease 2019–COVID-19.” Clinical Microbiology Reviews (2020) https://cmr.asm.org/content/33/4/e00028-20
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Stadnytskyi, Valentyn, et al. “The airborne lifetime of small speech droplets and their potential importance in SARS-CoV-2 transmission.” Proceedings of the National Academy of Sciences 117.22 (2020): 11875-11877. https://doi.org/10.1073/pnas.2006874117
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Cheng, Vincent CC, et al. “The role of community-wide wearing of face mask for control of coronavirus disease 2019 (COVID-19) epidemic due to SARS-CoV-2.” Journal of Infection (2020). https://doi.org/10.1016/j.jinf.2020.04.024
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Eikenberry, Steffen E., et al. “To mask or not to mask: Modeling the potential for face mask use by the general public to curtail the COVID-19 pandemic.” Infectious Disease Modelling (2020). https://doi.org/10.1016/j.idm.2020.04.001
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Greenhalgh, Trisha, et al. “Face masks for the public during the covid-19 crisis.” Bmj 369 (2020). https://doi.org/10.1136/bmj.m1435
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Cheng, Kar Keung, Tai Hing Lam, and Chi Chiu Leung. “Wearing face masks in the community during the COVID-19 pandemic: altruism and solidarity.” The Lancet (2020). https://doi.org/10.1016/S0140-6736(20)30918-1
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Davies, Anna, et al. “Testing the efficacy of homemade masks: would they protect in an influenza pandemic?.” Disaster medicine and public health preparedness 7.4 (2013): 413-418. https://dx.doi.org/10.1017%2Fdmp.2013.43
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Anatomy of Torso, Arms, and Legs
Intro
Torso anatomy
Arm anatomy
image by Joumana Medlej
Leg anatomy
image by Joumana Medlej
From Human Anatomy Fundamentals: Muscles and Other Body Mass
Apps
Leg muscles app – Healthline
Learning Standards
Massachusetts
6.MS-LS1-3. Construct an argument supported by evidence that the body systems interact to carry out essential functions of life.
6.MS-LS4-2. Construct an argument using anatomical structures to support evolutionary
relationships among and between fossil organisms and modern organisms.
HS-LS4-1. Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence, including molecular,
anatomical, and developmental similarities inherited from a common ancestor
(homologies), seen through fossils and laboratory and field observations.
SAT Subject area test in Biology
Organismal biology: Structure, function, and development of organisms (with emphasis on plants and animals), animal behavior
Female sexual anatomy
It is of critical importance for high school students to graduate high school with knowledge of how their bodies work. This includes sexual anatomy. In this resource we present anatomical information on external and internal female sexual anatomy.
There is a difference in student population between college level and high school level health and science classes. As such, we have taken care to select images that are anatomically correct yet not quite overt.
The vulva – external female sexual anatomy
The vulva includes
The inner and outer lips of the labia.
The clitoris.
The opening to the vagina (although the vagina itself is technically the long muscular opening moving back from this opening, see below.)
Vaginal glands, which are between the vulva and anus (the perineum).
The urethral opening. This is the opening to the urethra (the tube that carries urine outside of the body).
Image from Memorial Sloan Kettering Cancer Center
Above image from Memorial Sloan Kettering Cancer Center
Internal female reproductive system
Vagina (birth canal) – A muscular tube leading inside a woman’s body. Where sperm enters a woman. Also is where a baby is born from.
Cervix – The muscular wall at the end of the vagina. It has a tiny hole that sperm can swim through.
Uterus (womb) -A thick muscular organ. Has two purposes
(a) Allows sperm to pass, from the vagina, up towards the fallopian tubes
(b) If a woman becomes pregnant, the fetus will attach to the wall of the uterus and grow here.
Fallopian tubes – Tubes that connect the uterus to the ovary
(a) sperm swim up into these tubes. If the woman has recently released an egg, this is where the egg and sperm meet.
Ovary – these are where a woman’s eggs are stored. After puberty, women usually mature one egg a month.
Also see Human reproductive system
Also see Female reproductive system, Teens Health
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consciousness
It is easy to ask “what is the brain, and how does it work?” A much more difficult question is “what is the mind?,” and “what is consciousness?”
Introduction
Consciousness is “awareness or sentience of internal or external existence”.
Despite centuries of analyses, definitions, and debates by philosophers and scientists, consciousness remains puzzling and controversial. It is “at once the most familiar and most mysterious aspect of our lives”.
Perhaps the only widely agreed notion about the topic is the intuition that it exists. Opinions differ about what exactly needs to be studied and explained as consciousness.
Sometimes “consciousness” is synonymous with ‘the mind’, other times just an aspect of mind.
In the past it was one’s “inner life”, the world of introspection, of private thought, imagination and volition.
Today, with modern research into the brain it often includes any kind of experience, cognition, feeling or perception.
There might be different levels or orders of consciousness, or perhaps different kinds of consciousness – or just one kind with different features.
Other questions include whether only humans are conscious or all animals or even the whole universe. The disparate range of research, notions and speculations raises doubts whether the right questions are being asked.
( – Wikipedia, adapted, Consciousness)
Are there levels of consciousness?
Consciousness isn’t binary (It exists, or it doesn’t exist.)
Rather, it seems to exist on a smooth continuum from not at all, all the way up to what we humans experience.
There’s no reason to assume that our awareness & consciousness is the highest level – there may be higher levels, or different kids that we can’t imagine.
Image below from A better way to test for consciousness?
How does this relate to our bodies? What if we look at consciousness on the level of a person, and then down to smaller biological components?
Or what if we look at this on the level of a person, and then see how this changes when we look at how many people think when they interact?
“The scale problem of consciousness: Human conscious experience does not reflect information from every scale. Only information at a certain coarse-grained scale in the neural system is reflected in consciousness.”
Image from Chang, Acer & Biehl, Martin & Yu, Yen & Kanai, Ryota. (2019)
Information Closure Theory of Consciousness.
The hard problem of consciousness
“The meta-problem of consciousness is (to a first approximation) the problem of explaining why we think that there is a problem of consciousness.”
– Chalmers on the Meta-Problem
The hard problem of consciousness is the problem of explaining how atoms and molecules work together to create a living being – like us! – that actually feels and experiences the world.
How does a living person – like us! – experience awareness? How can we feel alive, experience our own thoughts – when we are built out of parts that have no awareness at all?
How the brain works is one thing – that’s the (relatively!) “easy” problem. We already have learned much about the anatomy of the brain and what kind of cells it is made of.
We’re learning how information is sent from our eyes, ears, skin, etc. to the brain. We have even begin to learn how the brain mechanically follows the laws of physics to store, recall, and process information.
But how can we humans (and presumably, animals) experience qualia – instances of subjective, conscious experience?
The philosopher David Chalmers is the first to clearly and forcefully make people aware of what an amazingly hard question is, this hard problem of consciousness.
Easy problems are (relatively) easy because all that is required for their solution is to specify a mechanism that can perform the function.
That is, regardless of how complex the phenomena of easy problems may be, they can eventually be understood by following science as we have always known it.
But the hard problem of consciousness will “persist even when the performance of all the relevant functions is explained”.
Chalmers, David (1995). “Facing up to the problem of consciousness” Journal of Consciousness Studies. 2 (3): 200–219.
On the other hand, the very existence of this hard problem is controversial. It has been accepted by many philosophers of mind but its existence is disputed by others.
Facing Up to the Problem of Consciousness, David J. Chalmers
Moving Forward on the Problem of Consciousness, David J. Chalmers
Consciousness as a State of Matter, Max Tegmark
Panpsychism: You are conscious but so is your coffee mug
Qualia Formalism in the Water Supply: Reflections on The Science of Consciousness 2018
Is consciousness an illusion?
(Text tba)
Has science shown that consciousness is an illusion?
Is Consciousness Real? Scientific American
The ‘me’ illusion: How your brain conjures up your sense of self
The consciousness illusion
There’s No Such Thing as Consciousness, According to Philosopher Daniel Dennett
Physical correlates of consciousness
If consciousness if real, then presumably it correlates to something going on in our brain.
What are the physical correlates of consciousness?
The controversial correlates of consciousness, George A. Mashour, Science 04 May 2018:
Vol. 360, Issue 6388, pp. 493-494, DOI: 10.1126/science.aat5616
https://science.sciencemag.org/content/360/6388/493/tab-figures-data
Neuroscience Readies for a Showdown Over Consciousness Ideas: To make headway on the mystery of consciousness, some researchers are trying a rigorous new way to test competing theories. Philip Ball, 3/6/2019, Quanta Magazine
Neuroscience Readies for a Showdown Over Consciousness Ideas
Visualizing how consciousness might work
Consciousness might be explained by it being an emergent phenomenon,
Analogy – we can’t predict the existence or behavior of oceans from looking at a single molecule of water.
Yet when enough liquid water molecules come together, an ocean – with all of its complex behavior – emerges.
Perhaps consciousness is similar. It might emerge from the interplay of dynamics that we already are beginning to learn about.
“Psychologist and neuroscientist Grit Hein and Ernst Fehr from the Department of Economics, University of Zurich teamed up with Yosuke Morishima, Susanne Leiberg, Sunhae Sul and found that the way relevant brain regions communicate with each other is altered depending on the motives driving a specific behavioral choice.”
Hein G, Morishima Y, Leiberg S, Sul S, & Fehr E (2016). The brain’s functional network architecture reveals human motives. Science, 351 (6277), 1074-8 PMI
and
Elucidating the Nature of Human Consciousness Through Art: interview with Greg Dunn
Do we really need new physics to understand consciousness?
Are the laws of physics, as we currently understand them, truly insufficient to explain what consciousness is? Many philosophers and writers make this claim. If so then we would need to postulate, look for, and prove the existence of undiscovered laws of physics.
Many claims in this area have been raised over the last two centuries. But physicist Sean Carroll warns us to be very careful if we make any such claim.
He writes – “Consciousness and the Laws of Physics” is a new paper where I review how we understand physics pretty well, and consciousness not so well, so altering physics to account for consciousness should be a last resort. And that if you try to alter the ontology of the world by adding intrinsically mental aspects to it, *without* modifying the laws of physics, you don’t really explain anything at all. The very first thing any attempt to account for consciousness should do is to be honest about whether it implies a modification of the known laws of physics. If yes, be very specific about how the equations change; if no, you’re not helping.
Philosophical zombies
In physics and philosophy, one way to learn about something is to create a gedankenexperiment (“thought experiment.”).
It may be possible to learn more about minds and consciousness by creating philosophical/biological thought experiments. The most well known one is the question of the philosophical zombie:
A philosophical zombie is a hypothetical being who is physically identical to a normal human being, but completely lacks conscious experience. – David Chalmers.
If a philosophical zombie is possible, then conscious experience is independent of physical world.
This image from Masatoshi Yoshida the-hard-problem-of-consciousness
Consciousness and the universe
“The universe is sentient. We all know that. We are the sentient bit. What could consciousness be, except the universe witnessing itself?”
– Steven Moffat
“We believe that the universe itself is conscious in a way that we can never truly understand. It is engaged in a search for meaning. So it breaks itself apart, investing its own consciousness in every form of life. We are the universe trying to understand itself.”
– J. Michael Straczynski
Related articles
Consciousness in Human and non-Human Animals
Possible minds
Consciousness creep Our machines could become self-aware without our knowing it
External articles
What Is Consciousness? Scientists are beginning to unravel a mystery that has long vexed philosophers, By Christof Koch, Scientific American, June 1, 2018
New Scientist articles
What Is Consciousness?
Consciousness, Stanford Encyclopedia of philosophy
Consciousness. Internet Encyclopedia of Philosophy
Articles on consciousness from New Scientist
Why can’t the world’s greatest minds solve the mystery of consciousness? The Guardian (article), UK
Why we need to figure out a theory of consciousness. The Conversation
How do viruses spread? Airborne vs non-airborne
How do viruses spread?
Not by individual virus particles
An individual virus particle is unbelievably tiny.
Since they are so lightweight they can float in the air for relatively long distances. So that makes them airborne, right?
Yet these airborne individual virus particles are almost never a problem. People are not at risk of being infected by single viral particle.
Why not? We’re always inhaling single viral particles here and there. They quickly break down in our bodies, or if they persist then our immune system quickly wipes them out.
So if that ain’t the problem then what is? The problem is when we encounter an exhaled drop of fluid which may have many hundreds or thousands of such viral particles.
Droplets from sneezing and coughing
Sneezing or coughing sends out lots of tiny water droplets. Each droplet could hold thousands of viral particles. If we inhaled some of these drops then that could make us sick.
Most droplets are short range.
Larger ones usually travel about six feet before they fall to the ground. That’s why it is important to practice social distancing. Stay at least six feet away from people outside of your home.
In a room with insufficient ventilation those droplets can stay in the air longer and travel further. That’s a real problem.
But in a room with good ventilation those drops stay in the air for a shorter period of time, and safety increases.
Image from paper by Jianjian Wei and Yuguo Li. Airborne spread of infectious agents in the indoor environment
Smaller droplets remain in the air longer
Larger particles fall quickly, but small particles float in the air longer – and then dehydrate ( lose water molecules.) That leaves an even lighter particle.
These lighter particles are sometimes called a bioaerosol. They can remain airborne much longer, over 20 feet.
So if you are indoors – like in a restaurant – the air could become saturated with lots of these tiny droplet nuclei, making the location unsafe.
Health authorities suggest wearing a mask if you have to do so. Even an imperfect mask is better than none at all.
Tiny aerosol drops, less than 5 microns across, can float for hours in a place with little ventilation.
A micron is 0.001 millimeters , or 0.000039 inch.
Its symbol is μm
SARS-CoV-2 thus is effectively an airborne virus.
researchers reported earlier this year in The New England Journal of Medicine that SARS-CoV-2 can float in aerosol droplets—less than 5 microns across—for up to 3 hours, and remain infectious
You may be able to spread coronavirus just by breathing, new report finds, Science, AAAS, Robert F. Service, 4/2/2020
Yes, wearing cloth face masks works!
Cloth masks can help stop the spread of COVID-19, save lives and restore jobs.
“Some people have said that covering their faces infringes on their rights, but…it’s about protecting your neighbors…Spreading this disease infringes on your neighbors’ rights.” –Larry Hogan, Governor of Maryland (Republican)
“If everybody’s wearing a mask, it will dramatically reduce the opportunity and possibility of spread.” –Charlie Baker, Governor of Massachusetts (Republican)
Countries that have contained major COVID-19 outbreaks have close to 100% mask usage. An international review of the scientific research on masks by 19 experts (from Stanford, MIT, Oxford, UPenn, Brown, UNC, UCLA, and USF) concluded that:
Near-universal adoption of non-medical masks in public (in conjunction with other measures like test & trace) can reduce effective-R below 1.0 and stop the community spread of the virus.
Laws appear to be highly effective at increasing compliance and slowing or stopping the spread of COVID-19.
There are “34 scientific papers indicating basic masks can be effective in reducing virus transmission in public — and not a single paper that shows clear evidence that they cannot.” –The Washington Post
Read more about the science.
Masks4All
References
Flight of the aerosol, Ian M Mackay et al. Virology Down Under, 2/9/2020
Simple DIY masks could help flatten the curve. We should all wear them in public.
Also see How do viruses spread? Airborne vs non-airborne
Jeremy Howard writes
When historians tally up the many missteps policymakers have made in response to the coronavirus pandemic, the senseless and unscientific push for the general public to avoid wearing masks should be near the top.
The evidence not only fails to support the push, it also contradicts it. It can take a while for official recommendations to catch up with scientific thinking. In this case, such delays might be deadly and economically disastrous.
It’s time to make masks a key part of our fight to contain, then defeat, this pandemic. Masks effective at “flattening the curve” can be made at home with nothing more than a T-shirt and a pair of scissors. We should all wear masks — store-bought or homemade — whenever we’re out in public.
At the height of the HIV crisis, authorities did not tell people to put away condoms. As fatalities from car crashes mounted, no one recommended avoiding seat belts. Yet in a global respiratory pandemic, people who should know better are discouraging Americans from using respiratory protection.
… There are good reasons to believe DIY masks would help a lot. Look at Hong Kong, Mongolia, South Korea and Taiwan, all of which have covid-19 largely under control. They are all near the original epicenter of the pandemic in mainland China, and they have economic ties to China.
Yet none has resorted to a lockdown, such as in China’s Wuhan province. In all of these countries, all of which were hit hard by the SARS respiratory virus outbreak in 2002 and 2003, everyone is wearing masks in public.
George Gao, director general of the Chinese Center for Disease Control and Prevention, stated, “Many people have asymptomatic or presymptomatic infections. If they are wearing face masks, it can prevent droplets that carry the virus from escaping and infecting others.”
My data-focused research institute, fast.ai, has found 34 scientific papers indicating basic masks can be effective in reducing virus transmission in public — and not a single paper that shows clear evidence that they cannot.
Studies have documented definitively that in controlled environments like airplanes, people with masks rarely infect others and rarely become infected themselves, while those without masks more easily infect others or become infected themselves.
Masks don’t have to be complex to be effective. A 2013 paper tested a variety of household materials and found that something as simple as two layers of a cotton T-shirt is highly effective at blocking virus particles of a wide range of sizes.
Oxford University found evidence this month for the effectiveness of simple fabric mouth and nose covers to be so compelling they now are officially acceptable for use in a hospital in many situations. Hospitals running short of N95-rated masks are turning to homemade cloth masks themselves; if it’s good enough to use in a hospital, it’s good enough for a walk to the store.
The reasons the WHO cites for its anti-mask advice are based not on science but on three spurious policy arguments.
First, there are not enough masks for hospital workers.
Second, masks may themselves become contaminated and pass on an infection to the people wearing them.
Third, masks could encourage people to engage in more risky behavior.
None of these is a good reason to avoid wearing a mask in public.
Yes, there is a shortage of manufactured masks, and these should go to hospital workers. But anyone can make a mask at home by cutting up a cotton T-shirt, tying it back together and then washing it at the end of the day. Another approach, recommended by the Hong Kong Consumer Council, involves rigging a simple mask with a paper towel and rubber bands that can be thrown in the trash at the end of each day.
… the idea that masks encourage risky behavior is nonsensical. We give cars anti-lock brakes and seat belts despite the possibility that people might drive more riskily knowing the safety equipment is there. Construction workers wear hard hats even though the hats presumably could encourage less attention to safety. If any risky behavior does occur, societies have the power to make laws against it.
Papers about effectiveness of basic masks #masks4all
About the author – Jeremy Howard is a distinguished research scientist at the University of San Francisco, founding researcher at fast.ai and a member of the World Economic Forum’s Global AI Council.
Simple DIY masks could help flatten the curve. We should all wear them in public.
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More reason to wear face masks:
Experts said the choir outbreak is consistent with a growing body of evidence that the virus can be transmitted through aerosols — particles smaller than 5 micrometers that can float in the air for minutes or longer.
The World Health Organization has downplayed the possibility of transmission in aerosols, stressing that the virus is spread through much larger “respiratory droplets,” which are emitted when an infected person coughs or sneezes and quickly fall to a surface.
But a study published March 17 in the New England Journal of Medicine found that when the virus was suspended in a mist under laboratory conditions it remained “viable and infectious” for three hours — though researchers have said that time period would probably be no more than a half-hour in real-world conditions.
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Nell Greenfieldboyce writes
the question of whether or not the coronavirus can be “airborne” is extremely contentious right now — and it’s a question that has real implications for what people should do to avoid getting infected.
… a committee of independent experts convened by the National Academies of Sciences, Engineering, and Medicine has weighed in, in response to a question from the White House Office of Science and Technology Policy about whether the virus “could be spread by conversation in addition to sneeze/cough-induced droplets.”
“Currently available research supports the possibility that SARS-CoV-2 could be spread via bioaerosols generated directly by patients’ exhalation,” says a letter from the committee chair. By bioaerosols, they are referring to fine particles emitted when someone breathes that can be suspended in the air rather than larger droplets produced through coughs and sneezes.
Even if additional research shows that any virus in such tiny particles is viable, researchers still won’t how much of it would need to be inhaled to make someone sick. But the committee experts also caution that uncertainty about all this is almost a given—because there’s currently no respiratory virus for which we know the exact proportion of infections that come from breathing the virus in versus coming into contact with droplets in the air or on surfaces.
“I personally think that transmission by inhalation of virus in the air is happening,” says Linsey Marr, an aerosol scientist at Virginia Tech. But she says so far, health experts have largely discounted the possibility of transmitting this coronavirus in this way.
“From an infection prevention perspective, these things are not 100% black and white. The reason why we say ‘droplet’ versus ‘airborne’ versus ‘contact’ is to give overall guidance on how to manage patients who are expected to be infectious with a specific pathogen,” said Dr. Hanan Balkhy, assistant director-general for antimicrobial resistance at WHO, in an interview with NPR earlier this week.
As an expert who worked to contain an outbreak of the deadly MERS coronavirus in Saudi Arabia, she believes that this new virus should behave similarly to other severe coronaviruses — and that means, unless health-care workers are doing invasive procedures like putting in breathing tubes, the virus is expected to primarily spread through droplets.
Droplets are larger respiratory particles that are 5 to 10 micrometers in size. Those are considered “big,” even though a 5 micrometer particle would still be invisible to the naked eye. Traditionally, those droplets are thought to not travel more than about three feet or so after exhalation. That would mean the virus can only spread to people who get close to an infected person or who touch surfaces or objects that might have become contaminated by these droplets. This is why public health messages urge people to wash their hands and stand at least 6 feet away from other people.
An “airborne” virus, in contrast, has long been considered to be a virus that spreads in exhaled particles that are tiny enough to linger in the air and move with air currents, letting them be breathed in by passersby who then get sick. Measles is a good example of this kind of virus — an exhaled measles pathogen can hang suspended in a room for a couple hours after an infected person leaves.
The reality of aerosol generation, however, is far more complex than this “droplet” versus “airborne” dichotomy would suggest, says Marr. People produce a wide range of different-sized particles of mucus or saliva. These particles get smaller as they evaporate in the air and can travel different distances depending on the surrounding air conditions.
“The way the definitions have been set up, this “droplet” vs “airborne” distinction, was first established in the 1950s or even earlier,” says Marr. “There was a more limited understanding of aerosol science then.”
Even a 5 micrometer droplet can linger in the air. “If the air were perfectly still, it would take a half hour to fall from a height of 6 feet down to the ground. And, of course, the air isn’t perfectly still,” says Marr. “So it can easily be blown around during that time and stay in the air for longer or shorter.”
What’s more, coughs and sneezes create turbulent clouds of gas that can propel respiratory particles forward.
“For symptomatic, violent exhalations including sneezes and coughs, then the droplets can definitely reach much further than the 1 to 2 meter [3 to 6 feet] cutoff,” says Lydia Bourouiba, an infectious disease transmission researcher at MIT, referring to the distance typically cited as safe for avoiding droplet-carried diseases.
In fact, studies show that “given various combinations of an individual patient’s physiology and environmental conditions, such as humidity and temperature, the gas cloud and its payload of pathogen-bearing droplets of all sizes can travel 23 to 27 feet,” she wrote in a recent article published online by the Journal of the American Medical Association.
…. Some of the strongest evidence that an airborne route of transmission might be possible for this virus comes from a report published last month by the New England Journal of Medicine that described mechanically generating aerosols carrying the SARS-CoV-2 virus in the laboratory. It found that the virus in these little aerosols remained viable and infectious throughout the duration of the experiment, which lasted 3 hours.
WHO mentioned this study in its recent review of possible modes of transmission and noted that “this is a high-powered machine that does not reflect normal human cough conditions … this was an experimentally induced aerosol-generating procedure.”
It may have been artificial, says Marr, but “the conditions they used in that laboratory study are actually less favorable for survival compared to the real world. So it’s more likely that the virus can survive under real world conditions.”
Scientists Probe How Coronavirus Might Travel Through The Air
Reference: Turbulent Gas Clouds and Respiratory Pathogen Emissions: Potential Implications for Reducing Transmission of COVID-19
Lydia Bourouiba, JAMA insights, March 26, 2020. doi:10.1001/jama.2020.4756
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Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1
March 17, 2020 , DOI: 10.1056/NEJMc2004973
A novel human coronavirus that is now named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (formerly called HCoV-19) emerged in Wuhan, China, in late 2019 and is now causing a pandemic. We analyzed the aerosol and surface stability of SARS-CoV-2 and compared it with SARS-CoV-1, the most closely related human coronavirus.
… We found that the stability of SARS-CoV-2 was similar to that of SARS-CoV-1 under the experimental circumstances tested. This indicates that differences in the epidemiologic characteristics of these viruses probably arise from other factors, including high viral loads in the upper respiratory tract and the potential for persons infected with SARS-CoV-2 to shed and transmit the virus while asymptomatic.
Our results indicate that aerosol and fomite transmission of SARS-CoV-2 is plausible, since the virus can remain viable and infectious in aerosols for hours and on surfaces up to days (depending on the inoculum shed).
These findings echo those with SARS-CoV-1, in which these forms of transmission were associated with nosocomial spread and super-spreading events, and they provide information for pandemic mitigation efforts.
Neeltje van Doremalen, Ph.D., Trenton Bushmaker, B.Sc.
National Institute of Allergy and Infectious Diseases, Hamilton, MT
Dylan H. Morris, M.Phil., Princeton University, Princeton, NJ, Myndi G. Holbrook, B.Sc.
National Institute of Allergy and Infectious Diseases, Hamilton, MT
Amandine Gamble, Ph.D.
University of California, Los Angeles, Los Angeles, CA
Brandi N. Williamson, M.P.H.
National Institute of Allergy and Infectious Diseases, Hamilton, MT
Azaibi Tamin, Ph.D., Jennifer L. Harcourt, Ph.D.
Natalie J. Thornburg, Ph.D., Susan I. Gerber, M.D.
Centers for Disease Control and Prevention, Atlanta, GA
James O. Lloyd-Smith, Ph.D.
University of California, Los Angeles, Los Angeles, CA, Bethesda, MD
Emmie de Wit, Ph.D., Vincent J. Munster, Ph.D.
National Institute of Allergy and Infectious Diseases, Hamilton, MT
Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1
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