Six on Geography and Science: A Close Look at Fall Colors; MIT Researchers 3D Print a Bridge Imagined by Leonardo da Vinci in 1502; the 20 firms behind a third of all carbon emissions; The Most Detailed Map of Auto Emissions in America; a climate cr
panaritisp
And please don't forget to check out the pertinent images attached to every post
Thanks John and Gary
"Basically, we have autumn in temperate zones because in the months of low sunlight, cold temperatures, and ice and snow storms, large, flat leaves would be a liability, said Wason.
Decreasing day length is a main driver of the timing of the color change and the resulting leaf drop. But temperature and precipitation also play roles. You can see this by looking at the side of a mountain, where trees at higher elevations typically change color earlier, reflecting colder temperatures, even though all of the trees on the mountainside are reading the same day length. The same holds true in low-lying areas, where colder air pools and creates fall-like temperatures sooner.
Plants sense changes in day length using special molecules called phytochromes, and react by curbing production of chlorophyll, the green pigment that is the heavy lifter when it comes to photosynthesis. As chlorophyll disappears, underlying yellow and orange pigments, called carotenoids, are unmasked. They’ve been there all along, but only become visible now.
Reds are something else. Known as anthocyanins, they’re produced in the fall, but we’re not really certain why. Wason said one hypothesis is that these red-reflecting pigments are helping to protect the leaves from damage by sunlight as the tree is working to siphon all the nutrients it can from its leaves, nitrogen being the most important.
Temperature and precipitation help determine how much of this red pigment is produced, and thus how colorful the fall will be. To make anthocyanins, the tree needs sugars, and to produce those sugars it needs moisture and sunlight. That’s why a fall drought can definitely put a damper on the season’s colors, said Wason.
As the leaves change colors, each forms a corky layer – the abscission layer – at the end of the stem, which weakens the bond to the twig and eventually cuts it free. After the leaves fall, the yellow, orange, and red pigments break down, leaving nothing but tannins that turn brown. It’s those same tannins that slow the breakdown of leaves and allow them to become a mulch layer on the forest floor."
|
"Unfortunate though it may be for the dreamers of the world, we're all judged not by what we imagine, but what we actually do. This goes double for those specifically tasked with creating things in the physical environment, from engineers and architects to inventors and artists. Leonardo da Vinci, the original "Renaissance man," was an engineer, architect, inventor, artist, and more besides, and five centuries after his death we continue to admire him for not just the works of art and technology he realized during his lifetime, but also the ones that never made it off his drawing board (or out of his notebooks). And as we continue to discover, many of the latter weren't just flights of fancy, but genuine innovations grounded in reality.
At the time, such bridges required the support of piers all along their spans, which prevented large ships from passing underneath. But Leonardo's design would do the job with only "a single enormous arch." About ten times longer than the typical bridge of the early 16th century, it took a page from the bridges of ancient Rome, designed as it was to "stand on its own under the force of gravity, without any fasteners or mortar to hold the stone together."
|
|
|
The map below shows a year’s worth of CO2 from passenger and freight traffic on every road in the New York metro area"
|
1959
The physicist Edward Teller tells the American Petroleum Institute (API) a 10% increase in CO2 will be sufficient to melt the icecap and submerge New York. “I think that this chemical contamination is more serious than most people tend to believe.”
|
|
Since the idea for the film was born, the documentary has become more and more important, says Thaver.
“In the early days, we felt it was an important story to tell because of its power to inspire children back home and to educate about a Pakistani, Muslim Nobel Prize winner who was an unsung hero,” says Thaver. “Over the years the plight of religious minorities in Pakistan, as well as the sub-continent at large, has worsened, and that’s given greater present-day significance and relevance to the story.” On top of this, he says, rising Islamophobia in the West makes Salam’s story even more relevant by celebrating Muslim achievement, particularly in science, where the Islamic world’s contribution has been underappreciated.
“Inequality in every sense is higher now than ever in history,” says Ahmad. “Abdus Salam strived to make developing countries invest in education, science and technology to help their economic prospects, whereby they would grow faster and more sustainably with the support of the developed countries. That message is as relevant now as it was 50 years ago.”
|
