Posts about how things work

Biology: How Wounds to Our Skin Heal

This is an interesting webcast looking at how our bodies heal wounds to our skin.

Related: Science Explained: How Cells React to Invading VirusesTissue Regeneration in AnimalsScience Explained: Cool Video of ATP Synthase, Which Provides Usable Energy to UsLooking Inside Living CellsA Healthy Lifestyle is More About Health Care than the Sickness Management That We Call Health Care Is

Lots of Bacteria are Always Living in Our Bodies

My response to a question on Reddit – Ask Science:

Let’s say you get infected with a bacterium that causes annoying, but totally non-dangerous symptoms. If you just try to “live with it,” will your immune system eventually kill it, or does killing bacteria require antibiotics in all cases?

Your body definitely kills lots of bacteria.

Your body also has tons of bacteria all the time (many doing much more good than they do harm). These bacteria also compete with each other.

So your “existing” bacteria kill off others all the time too (you have lots of different types of bacteria full time in your body – they often settle into niches and fight off any others , which is normally good as they are long term residents your body has learned to live with them).

Also like everything bacteria die off themselves – though if the conditions are right they are multiplying like crazy so that exceeds die off.

An astonishing number and variety of microbes, including as many as 400 species of bacteria, help humans digest food, mitigate disease, regulate fat storage, and even promote the formation of blood vessels.

According to estimates, phages destroy up to 40 percent of the bacteria in Earth’s oceans each day.

Staphylococcal food poisoning – an example of bacteria infection my body dealt with quickly.

People talk about genetics impact on getting cavities and impact of brushing and flossing well. Also the makeup of bacteria can help or hurt. If your mouth is home to certain bacteria tooth decay is less likely, home to others it is more likely. They tend to remain fairly steady (a certain makeup of bacteria will be consist for a person over the long term – not perfectly that way but tend that way). A UCLA microbiologist developed a mouthwash to try and ceed your mouth with good bacteria and oust the bad guys.

Related: People Have More Bacterial Cells than Human CellsHuman Gene Origins: 37% Bacterial, 35% Animal, 28% Eukaryotic

Looking Inside Living Cells

Johns Hopkins’ molecular biologist Jin Zhang explains how she uses light to see where and when within cells specific molecular processes occur and what happens when they go wrong.

Related: How Lysozyme Protein in Our Tear-Drops Kill BacteriaScience Explained: How Cells React to Invading VirusesNobel Prize in Physiology or Medicine 2012 for Reprogramming Cells to be PluripotentWebcast Exploring Eukaryotic Cells

How Do You Lose Weight While You Sleep?

In this interesting webcast, Derek Muller, (a physics teacher in Perth, Australia) explores how much weight you lose while you sleep. As physics teacher he asks the sensible question: how do you lose weight while you sleep, what weight do you lose?

His conclusion is you lose weight through perspiration, water vapor in your breath and expelling carbon dioxide. Losing the water weight is pretty straight forward. The process of adding carbon to the breath we expel is not something I thought of. He calculates that we lose about 100 grams of carbon during a night of sleep. In his somewhat scientific experiment (measuring himself for several days) he lost about 150 more grams, which he attributes to water vapor and perspiration.

It seems to me the amount of carbon we lose during sleep is probably much more consistent than the amount of water weight we lose (both between people and variation between different days).

Related: Can You Effectively Burn Calories by Drinking Cold Water?CDC Urges Reducing the Amount of Salt We EatWhy is it Colder at Higher Elevations?How Caffeine Affects Your BodyWhy Does the Moon Appear Larger on the Horizon?

Can You Effectively Burn Calories by Drinking Cold Water?

Neil deGrasse Tyson stated on Twitter:

Wanna lose 1200 Calories a month? Drink a liter of ice water a day. You burn the energy just raising the water to body temp.

What if your body is trying to cool down? I would imagine we have to use energy to cool off (though I am no expert on this)? So if you drink cold water and your body has less need to cool off, couldn’t this actually end up “saving” your body needing to burn calories – and thus cause yourself to gain weight?

This model would be similar to a server room that was cooled with air conditioning and cold winter air to cool off the servers. If there was less cold air used then more electricity would be used running the air conditioner to cool down the servers. I don’t know if it is a decent analogy though – maybe that isn’t an usable model for how we cool off.

I know we cool off partially by pushing water out onto the exterior of our skin to have it evaporate and cool us off. I would think that takes energy to do.

I do get that it takes energy to raise the temperature of the water you consume. It does make sense to me that if you were cold (like say I was during the winter living in the house I grew up in) you would use energy raising the temperature of the water.

What the overall energy situation is if your body needs to cool down seems questionable to me. Please let me know your thoughts. In any event his statement is accurate. It is just that the implication may lead people astray; that you can consume 1,200 Calories extra to balance the 1,200 Calories drinking cold water uses (or loss weight by having reduced your excess Calories by 1,200 if you eat exactly the same things you would without the cold water).

Related: Why is it Colder at Higher Elevations?Does Diet Soda Result in Weight Gain?Why Does Hair Turn Grey as We Age?How Corn Syrup Might Be Making Us FatWhy Wasn’t the Earth Covered in Ice 4 Billion Years Ago (When the Sun was Dimmer)

How Caffeine Affects Your Body

From the video by Alex Dainis: Caffeine prevents adenosine from slowing down your nervous system, by binding to the same receptors adenosine would. Caffeine also stimulates the production of adrenaline. And it increases the amount of dopamine present. The average half life of caffeine in the human body is about 6 hours.

Related: Does Diet Soda Result in Weight Gain?Mental Pick-Me-Ups: The Coming BoomRitalin Doesn’t Show Long Term Effectiveness for ADHD

I have been curious about the caffeine content of various drinks and writing this post is a good enough reason to actually look it up.

  • expresso (2oz) 100 mg (varies – 60 mg to 180 mg)
  • coffee (8oz) 100 mg – this can vary quite a bit, 50 to over 100 mg is common. Brewed coffee has more caffeine 100-200 mg.
  • Red Bull (8.2 oz) 80 mg
  • tea (8oz) 20 to 80 mg (depending on strength and type, can also be higher, green tea is on the lower end)
  • Mountain Dew (12 oz) 54 mg (diet has 54 mg also)
  • Diet Coke 46 mg (regular Coke 34mg)
  • Pepsi 38 mg, Diet Pepsi 36 mg

Sprite, 7Up and some root beers have no caffeine.
Chocolate can also be a significant source of caffeine – dark chocolate can have over 80 mg per 100 g (approximately 4 ounces).

Repair Cafes in The Netherlands

Repair Cafes in The Netherlands Give Life Back to Broken Objects

A new brand of DIY self-sufficiency is spreading across The Netherlands. Skilled craftswomen, mechanics, seamstresses, and handypersons are banding together to resist disposable consumer culture. It is the rise of the Repair Cafe, a place where neighbors get together to extend the life of their material belongings. “Fixers” mend clothes, restore furniture, rehabilitate electrical appliances, and enjoy each other’s company while industriously toiling away. The first cafe was founded by Martine Postma in Amsterdam in October of 2009. Today, there are 20 fully operational Repair Cafes, and 50 more in the planning stages.

I really like these efforts. We throw away too much stuff that has plenty of useful life left. Also it is a great way to build community. And it is an interesting way to learn about products we use everyday (both by fixing them and having your items fixed). The throw away culture is something we should aim to change. By these actions and also by engineers designing products to be fixed instead of thrown away. I donated to a similar fixer collective in Brooklyn via Kickstarter.

Related: Fix it GooBook Explores Adventures in MakingTeaching Through Tinkering

How do Plants Grow Into the Sunlight?

Plants are extremely competitive in gaining access to sunlight. A plant’s primary weapon in this fight is the ability to grow towards the light, getting just the amount it needs and shadowing its competition. Now, scientists have determined precisely how leaves tell stems to grow when a plant is caught in a shady place.

photo of a forest

Hole in the Wall trail, Olympic National Park, Washington, USA by John Hunter

The researchers discovered that a protein known as phytochrome interacting factor 7 (PIF7) serves as the key messenger between a plant’s cellular light sensors and the production of auxins, hormones that stimulate stem growth.

“We knew how leaves sensed light and that auxins drove growth, but we didn’t understand the pathway that connected these two fundamental systems,” says Joanne Chory, professor and director of the Salk’s Plant Biology Laboratory and a Howard Hughes Medical Institute investigator (HHMI provides huge amounts of funding for scientific research). “Now that we know PIF7 is the relay, we have a new tool to develop crops that optimize field space and thus produce more food or feedstock for biofuels and biorenewable chemicals.”

Plants gather intelligence about their light situation—including whether they are surrounded by other light-thieving plants—through photosensitive molecules in their leaves. These sensors determine whether a plant is in full sunlight or in the shade of other plants, based on the wavelength of red light striking the leaves. This is pretty cool; I love to learn about the brilliant strategies that have evolved.

If a sun-loving plant, such as thale cress (Arabidopsis thaliana), the species Chory studies, finds itself in a shady place, the sensors will tell cells in the stem to elongate, causing the plant to grow upwards towards sunlight.

When a plant remains in the shade for a prolonged period, however, it may flower early and produce fewer seeds in a last ditch effort to help its offspring spread to sunnier real estate. In agriculture, this response, known as shade avoidance syndrome, results in loss of crop yield due to closely planted rows of plants that block each other’s light.

Continue reading

Volleyball Sized Hail

photo of volleyball sized hail

On July 23, 2010, a severe thunderstorm struck Vivian, South Dakota, USA, a quiet rural community of less than 200. While there was nothing unusual about a violent summer storm, the softball (and larger)-sized hail that accompanied it was extraordinary. In fact, it led to the discovery of the largest hailstone ever recorded in the United States.

Once the thunderstorm passed, Vivian resident Les Scott ventured outside to see if there was any damage as a result of the storm. He was surprised to see a tremendous number of large hailstones on the ground, including one about the size of a volleyball. Scott gathered up that stone, along with a few smaller ones, and placed them in his freezer.

How does hail form?

  • Inside of a thunderstorm are strong updrafts of warm air and downdrafts of cold air.
  • If a water droplet is picked up by the updrafts…it can be carried well into colder zones and the water droplet freezes.
  • As the frozen droplet begins to fall, carried by cold downdrafts, it may partially thaw as it moves into warmer air toward the bottom of the thunderstorm
  • But, if the little half-frozen droplet get picked up again by another updraft and is carried back into very cold air it will re-freeze. With each trip above and below the freezing level our frozen droplet adds another layer of ice.
  • Finally, the frozen hail, with many layers of ice, much like the rings in a tree falls to the ground.

According to NOAA, the Kansas City hail storm on April 10, 2001 was the costliest hail storm in the U.S. which caused damages of an estimated $2 billion.

Image from NOAA

Related: 500 Year FloodsClouds Alive With BacteriaRare “Rainbow” Over IdahoWhy is it Colder at Higher Elevations?

Sylvia’s Super Awesome Mini Maker Show: Rockets

Watch this fun webcast on how to make a rocket.

Related: Home Engineering: Bird Feeder That Automatically Takes Photos When Birds FeedLego Autopilot Project UpdateYoung Engineers Build Bridges with SpaghettiHome Engineering: Building a Hovercraft

Fiber to the Home

A very simple overview of fiber to the home.

Related: Plugging America’s Broadband GapNext steps for Google’s Experimental Fiber NetworkNet Neutrality, Policy, Economics and Intelligent EngineeringHow Do You Fix an Undersea Cable?

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