Tag Archives: science explained

Science Explained: Cool Video of ATP Synthase, Which Provides Usable Energy to Us

[I replaced the webcast – as so often happen the non-Youtube video embed failed to work as time passed]

This webcast shows animations of ATP synthase structure and the mechanism for synthesizing ATP. Biology is incredibly cool. Too bad they didn’t have stuff like this when I was in school, instead biology was mainly about memorizing boring lists of stuff.

ATP (adenosine tri-phosphate) transports chemical energy within cells. When one of the phosphates is released by ATP energy is given off (and ATP becomes ADP (adenosine di-phosphate) + Pi (inorganic phosphate). And then the synthase structure can then turn it back into ATP to be used again.

The human body, which on average contains only 250 grams of ATP, turns over its own body weight equivalent in ATP each day.

The Science Behind Hummingbird Flight

Aerodynamics of the hovering hummingbird

Hummingbirds and insects have evolved for sustained hovering ï¬‚ight from vastly different ancestral directions, and their distinct phylogenies underlie the differences in their aerodynamic styles. In all other birds—and, presumably, hummingbird ancestors—the downstroke provides 100% of weight support during slow ï¬‚ight and hovering. Given that many birds possess the mass-speciï¬c power (using anaerobic metabolism) to hover for short periods, the selective pressure on hummingbird ancestors was probably for increased efï¬ciency (resulting in stiff wings with greatly simpliï¬ed
kinematics), and an upstroke muscle (the supracoracoideus) that makes the recovery stroke rapid, while contributing enough to the hovering power requirements to allow the downstroke muscle (the pectoralis) to operate within its aerobic limits.

In other words, this pseudosymmetrical wingbeat cycle is good enough, and although hummingbirds do not exhibit the elegant aerodynamic symmetry of insects, natural selection rewards ‘good enough’ as richly as it does our aesthetic ideals

Great Webcast Explaining the Digestive Systems

You will learn things like why it is so important to chew your food well (increase the surface area for enzymes to get at the food). Our bodies also have adapted to provide a huge surface area for the digestive system to work; the small intestine alone has a surface area of 250 square meters (larger than the size of most apartments). Your small intestine is 4.5 to 10.5 meters long.

The Appendix Serves As a Reservoir of Beneficial Bacteria

This is an interesting explanation for the purpose of the appendix.

The appendix does have a use – re-booting the gut

The US scientists found that the appendix acted as a “good safe house” for bacteria essential for healthy digestion, in effect re-booting the digestive system after the host has contracted diseases such as amoebic dysentery or cholera, which kill off helpful germs and purge the gut.

This function has been made obsolete by modern, industrialised society; populations are now so dense that people pick up essential bacteria from each other, allowing gut organisms to regrow without help from the appendix, the researchers said.

But in earlier centuries, when vast tracts of land were more sparsely populated and whole regions could be wiped out by an epidemic of cholera, the appendix provided survivors with a vital individual stockpile of suitable bacteria.

The Chemistry of Fireworks

The video features John A. Conkling, Ph.D., who literally wrote the book on fireworks — he is the author of The Chemistry of Pyrotechnics.

The earliest documentation of fireworks dates back to 7th century China.

A Syrian named Hasan al-Rammah wrote of rockets, fireworks, and other incendiaries, using terms that suggested he derived his knowledge from Chinese sources, such as his references to fireworks as “Chinese flowers”.

Chinese fireworks began to gain popularity around the mid-17th century.

Scientific Inquiry Process Finds More Evidence Supporting Einstein’s Theory

As scientists have been able to see farther and deeper into the universe, the laws that govern its expansion have been revealed to be under the influence of an unexplained force.

In a paper on the arXiv, Astrophysical Tests of Modified Gravity: Constraints from Distance Indicators in the Nearby Universe, are a vindication of Einstein’s theory of gravity. Having survived several decades of tests in the solar system, it has passed this new test in galaxies beyond our own as well.

In 1998, astrophysicists made an observation that turned gravity on its ear: the universe’s rate of expansion is speeding up. If gravity acts the same everywhere, stars and galaxies propelled outward by the Big Bang should continuously slow down, like objects thrown from an explosion do here on Earth.

This observation used distant supernovae to show that the expansion of the universe was speeding up rather than slowing down. This indicated that something was missing from physicists’ understanding of how the universe responds to gravity, which is described by Einstein’s theory of general relativity. Two branches of theories have sprung up, each trying to fill its gaps in a different way.

One branch — dark energy — suggests that the vacuum of space has an energy associated with it and that energy causes the observed acceleration. The other falls under the umbrella of “scalar-tensor” gravity theories, which effectively posits a fifth force (beyond gravity, electromagnetism and the strong and weak nuclear forces) that alters gravity on cosmologically large scales.

“These two possibilities are both radical in their own way,” University of Pennsylvania astrophysicist Bhuvnesh Jain said. “One is saying that general relativity is correct, but we have this strange new form of energy. The other is saying we don’t have a new form of energy, but gravity is not described by general relativity everywhere.”

Jain’s research is focused on the latter possibility; he is attempting to characterize the properties of this fifth force that disrupts the predictions general relativity makes outside our own galaxy, on cosmic length scales. Jain’s recent breakthrough came about when he and his colleagues realized they could use the troves of data on a special property of a common type of star as an exquisite test of gravity.

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Video of Young Richard Feynman Talking About Scientific Thinking

The enjoyable video above shows a young Richard Feynman discussing how scientific thinking can advance our understanding of the world.

New Blog with Simple Demonstrations and Scientific Explanations

Try this at home is a new blog by Dr Mark Lorch, a chemistry lecturer at the University of Hull, with instructions for the citizen scientist. This example shows how to move a can with a ballon without touching the can.

The posts include instructions on how to do these simple demonstrations and a nice explanation on the scientific reason for what is going on:

Rubbing the balloon on your hair charges it up with static electricity which makes the balloon negatively charged. When you put the balloon near the can it pushes electrons (which are also negatively charged) to the other side of the can. This makes the side which is nearest the balloon positively charged. Positive charges are attracted to negative charges so the can moves towards the balloon.

It is quite a nice site (especially if you have kids interested in science or are a kid interested in science – no matter how old you are), add it to your RSS reader. Here are some more science blogs you may enjoy.

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.

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.

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Dangerous Drug-Resistant Strains of TB are a Growing Threat

Drug-resistant strains of TB are out of control

The fight against new, antibiotic-resistant strains of tuberculosis has already been lost in some parts of the world, according to a senior World Health Organisation expert.
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Dr Paul Nunn, head of the WHO’s global TB response team, is leading the efforts against multi-drug resistant TB (MDR-TB). Nunn said that, while TB is preventable and curable, a combination of bad management and misdiagnosis was leaving pharmaceutical companies struggling to keep up. Meanwhile, the disease kills millions every year.

“It occurs basically when the health system screws up,” said Nunn. “Treating TB requires a carefully followed regime of medication over six months. In places where health services are fragmented or underfunded, or patients poor and health professionals ill-trained, that treatment can fall short, which can in turn lead to patients developing drug-resistant strains. It’s been estimated that an undiagnosed TB-infected person can infect 10 others a year.

We tend to do a poor job of dealing with systemic effects of poorly functioning systems. Direct present threats get out attention. And we are decent at directing brain power and resources to find solutions. We are not very good at dealing with failures that put us in much worse shape in the long term. For small threats we can wait until it becomes a present threat and then deal with it. There are costs to doing this (economic and personal) but it can be done.

Some problems though become enormously complicated to deal with once they become obvious. Global climate change, for example. And often, even once they are obvious, we won’t act until the costs (economic and in human lives) are very large. It is possible that once we decide to get serious about dealing with some of these issues that the costs (economic and in human lives) will be catastrophic.

The failure to use anti-biotics medicine properly is a very serious threat to become one of these catastrophic societal failures. While tuberculosis failures may be larger in poorer countries, rich countries are failing probably much more critically in the misuse of anti-biotics (I would guess, without having much evidence at my fingertips to back up my opinion. I believe the evidence exists I am just not an expert). These failures have huge costs for all of humanity but we are risking many premature deaths because we systemically fail to deal with issues until the consequences are immediate.