Personality Cafe banner

41 - 60 of 612 Posts

·
Banned
Joined
·
21,040 Posts
Discussion Starter #41
A giant lava lamp inside the Earth might be flipping the planet's magnetic field

theconversation.comPaula Koelemeijer

If you could travel back in time 41,000 years to the last ice age, your compass would point south instead of north. That’s because for a period of a few hundred years, the Earth’s magnetic field was reversed. These reversals have happpened repeatedly over the planet’s history, sometimes lasting hundreds of thousands of years. We know this from the way it affects the formation of magnetic minerals, that we can now study on the Earth’s surface.

Several ideas exist to explain why magnetic field reversals happen. One of these just became more plausible. My colleagues and I discovered that regions on top of the Earth’s core could behave like giant lava lamps, with blobs of rock periodically rising and falling deep inside our planet. This could affect its magnetic field and cause it to flip. The way we made this discovery was by studying signals from some of the world’s most destructive earthquakes.

Around 3,000km below our feet – 270 times further down than the deepest part of the ocean – is the start of the Earth’s core, a liquid sphere of mostly molten iron and nickel. At this boundary between the core and the rocky mantle above, the temperature is almost 4,000℃ degrees, similar to that on the surface of a star, with a pressure more than 1.3m times that at the Earth’s surface.

On the mantle side of this boundary, solid rock gradually flows over millions of years, driving the plate tectonics that cause continents to move and change shape. On the core side, fluid, magnetic iron swirls vigorously, creating and sustaining the Earth’s magnetic field that protects the planet from the radiation of space that would otherwise strip away our atmosphere.

Because it is so far underground, the main way we can study the core-mantle boundary is by looking at the seismic signals generated by earthquakes. Using information about the shape and speed of seismic waves, we can work out what the part of the planet they have travelled through to reach us is like. After a particularly large earthquake, the whole planet vibrates like a ringing bell, and measuring these oscillations in different places can tell us how the structure varies within the planet.
New model Earth? Shutterstock In this way, we know there are two large regions at the top of the core where seismic waves travel more slowly than in surrounding areas. Each region is so large that it would be 100 times taller than Mount Everest if it were on the surface of the planet. These regions, termed large-low-velocity-provinces or more often just “blobs”, have a significant impact on the dynamics of the mantle. They also influence how the core cools, which alters the flow in the outer core.

Several particularly destructive earthquakes over recent decades have enabled us to measure a special kind of seismic oscillations that travel along the core-mantle boundary, known as Stoneley modes. Our most recent research on these modes shows that the two blobs on top of the core have a lower density compared to the surrounding material. This suggests that material is actively rising up towards the surface, consistent with other geophysical observations.

These regions might be less dense simply because they are hotter. But an exciting alternative possibility is that the chemical composition of these parts of the mantle cause them to behave like the blobs in a lava lamp. This would mean they heat up and periodically rise towards the surface, before cooling and splashing back down on the core.

Such behaviour would change the way in which heat is extracted from the core’s surface over millions of years. And this could explain why the Earth’s magnetic field sometimes reverses. The fact that the field has changed so many times in the Earth’s history suggests that the internal structure we know today may also have changed.

We know the core is covered with a landscape of mountains and valleys like the Earth’s surface. By using more data from Earth oscillations to study this topography, we will be able to produce more detailed maps of the core that will give us a much better understanding of what is going on deep below our feet.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #42
Why these researchers think dinosaurs were minutes away from surviving extinction

washingtonpost.com


[HR][/HR] The asteroid that wiped out the dinosaurs 66 million years ago left a massive crater off the coast of Mexico's Yucatan Peninsula. Scientists are finally drilling into the Chicxulub crater to see what secrets it holds.

Scientists are finally drilling into the Chicxulub crater to see what secrets it holds.

(Jenny Starrs/The Washington Post)

The asteroid that wiped out the dinosaurs 66 million years ago left a massive crater off the coast of Mexico's Yucatan Peninsula. Scientists are finally drilling into the Chicxulub crater to see what secrets it holds. (Jenny Starrs/The Washington Post)

From our standpoint 66 million years later, it's easy to assume the demise of the dinosaurs was an inevitability.

But an international team of researchers is making a radical argument for why that may not be the case: Had the asteroid that likely wiped out the dinosaurs slammed into the planet a few minutes earlier or later, the scientists say, the fabled reptiles could still be walking the earth now.

That conclusion makes up one of the most intriguing revelations in “The Day the Dinosaurs Died,” a BBC Two documentary that was filmed across three continents during the past year before airing this week.

How is it possible dinosaurs could still be alive?

If the massive asteroid that smashed into present-day Yucatan hit the Atlantic Ocean or somewhere else, the scientists maintain, the rock would have avoided an area made up primarily of limestone and evaporated ocean sediments and rich in carbon dioxide, sulfur and deadly gypsum. Due to the earth's rotation, even a minute or two could have significantly changed the outcome of the impact.

It was, for all intents and purposes, a kill shot for the giant reptiles roaming the planet.
“When the asteroid hits with the force of something like 10 billion Hiroshima explosions, all of that gets pumped up in the atmosphere, and it may have been really critical for the mass extinction that followed as it blocked out the sun,” Sean P. Gulick, a University of Texas professor who studies catastrophism in the geologic record, told The Washington Post. “A few minutes earlier or later and the asteroid would've hit the Atlantic or the Pacific Ocean and not slammed into a big, volatile platform that was then vaporized as it spread upward and out.”
[How T. rex’s powerful bite crushed dino bones to a pulp]

Known as the Chicxulub crater, the impact zone lies 24 miles off the Yucatán Peninsula in Mexico. The impact left in its wake a hole in the Earth 20 miles deep and 120 miles across, scientists say, a site that is now covered completely by 66 million years worth of solid rock and sediment.

To reach their shocking conclusion, the scientists drilled through that rock and into the site of impact crater more than 1,300 meters below the seafloor. Gulick, who appears in the BBC Two program, said drilling into the crater is something he's been pushing for, with grant proposals and lobbying, for more than 15 years.

“The idea was a little outside of the box,” he said. “When scientists are seeking funding, most of the time people are going after some question about past climates or earthquakes or some very fundamental ocean earth science topic, but we were saying we wanted to drill into an impact crater, which has a different ring to it.”

“It just so happens that this particular crater had an extremely important role in the history of our planet,” he added.

Though many scientists say the impact of an asteroid caused many dinosaurs to vanish, the idea remains a widely accepted theory. Using seismic images that showed researchers where they could find the crater's central impact zone, known as the “peak ring,” the scientists said they were looking for physical evidence to bolster the theory.

With that in mind, they had three different goals:

1. Better understanding physical processes that shape impact craters.
2. Investigating the different “kill mechanisms” in place, such as the type of material released into the atmosphere, that may have caused the extinction of the dinosaurs.
3. Studying the microbial life that moved into the subsurface in the wake of the impact.
Eight weeks of intensive drilling were required to collect more than 260 rock cores, which were extracted and taken to the University of Bremen in Germany for examination, according to BBC Two.

That analysis — requiring 800 meters of rock being split, tested and photographed — resulted in some extraordinarily detailed insights. The scientists believe they have proved that the asteroid that smashed into the Yucatan Peninsula was moving at 40,000 mph and instantly vaporized upon hitting the water.

It was, BBC Two notes, the equivalent of a grain of sand slamming into a bowling ball, but the impact was so powerful and hot that it turned the surrounding sea to steam and traveled miles into the earth's crust. The rock that was pushed upward, the scientists found, formed “a tower higher than the Himalayas” before collapsing to “form a strange ring of peaks that exists today,” according to BBC Two.

All of it, the researchers found, took place in the space of 10 minutes.
“It's an amazing oceanographic event, even more so because we see in the cores that life came back pretty quickly,” Gulick said. “We discovered that organisms started to evolve within the sea floor at the crater within a few tens of thousands of years — we know for certain by 30,000 years.”

[‘Rare as winning the lottery’: New dinosaur fossil so well-preserved it looks like a statue]
What followed immediately after the impact was a scene reminiscent of a modern-day nuclear holocaust, mixed with profound natural disasters on a mind-boggling scale.

A radioactive fireball that reached 18,000 degrees scorched the Earth for 600 miles in every direction and unleashed the largest tsunami in history, Gulick said. A deadly vapor containing billions of tons of sulfates fanned out over the globe, blocking sunlight and lowering temperatures, while molten material from the crater rained down upon the Earth for thousands of miles in every direction, starting fires and turning the atmosphere into an oven, according to BBC Two.

Ben Garrod, an evolutionary biologist who appears in the program, said global temperatures plunged more than 50 degrees within days.

“This is where we get to the great irony of the story — because in the end it wasn’t the size of the asteroid, the scale of blast, or even its global reach that made dinosaurs extinct — it was where the impact happened,” Garrod said.

“In this cold, dark world, food ran out of the oceans within a week and shortly after on land,” he added. “With nothing to eat anywhere on the planet, the mighty dinosaurs stood little chance of survival.”

The dinosaurs' sudden ending did have an upside, according to Alice Roberts, a professor of public engagement in science at the University of Birmingham, who appears throughout the documentary.

“Just half a million years after the extinction of the dinosaurs and landscapes around the globe had filled with mammals of all shapes and sizes,” she said. “Chances are, if it wasn’t for that asteroid, we wouldn’t be here to tell the story today.”
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #43 (Edited)
Tinder for T. rex: Experts helped us write dating profiles for dinosaurs

washingtonpost.com https://www.facebook.com/sarah.kaplan.31

[HR][/HR] The moment I read the phrase, “Tyrannosaurus rex was a sensitive lover, new dinosaur discovery suggests,” I thought it sounded like the opening line to a dinosaur's Tinder profile.

Turns out it was just the headline on a Guardian article covering new research suggesting that T. rex dinosaurs had hypersensitive snouts that could have been used in mating.

But I rather like the idea of a dating profile for a dinosaur. So, in a fit of caffeine-induced absurdity, I decided to write one myself. I managed to talk Emily Chow, one of The Washington Post's top-notch designers, into making it look like a real Tinder profile.




But a dating app is no use to a lonely dino if he's the only guy on it. So I emailed a bunch of paleontologists and asked whether they would be willing to create a profile for their favorite dinosaurs.

Turns out, crafting a profile that will charm a dinosaur is even harder than trying to date a human. There's a lot scientists don't know about dinosaur lifestyles — whether a given species lived in herds or alone, how often they mated and with whom, whether they cared for their young — so it's hard to tell what would appeal to them.

But paleontologists are a pretty resourceful bunch. Not to mention hilarious (and surprisingly raunchy). Here's how they would attempt to woo a dinosaur mate. Which would you swipe right on?

Dreadnoughtus schrani: One of history's largest land animals, this gigantic South American sauropod was discovered in 2014.

Full-bodied sauropod, enjoys standing and eating. Turnoffs: Interrupting me while I’m eating; things I can’t eat; gravity. If you’re into to doing terrible things to ferns, drop me a line and we’ll defoliate together.

— Kenneth Lacovara, paleontologist at Rowan University

Anzu wyliei: A gigantic oviraptor species unofficially known as “the chicken from Hell.”
SD > ND > MT. Snacks on fruit, lizards, mammals, and Triceratops eggs. Likes flashy wing and tail plumage and a great head crest. Daddy to 22 beautiful chicks. 7' 5" so you gotta be tall. No comparisons to poultry please. :) LOL

— Matthew Lamanna, assistant curator of vertebrate paleontology at the Carnegie Museum of Natural History

Parasaurolophus walkeri: A North American duck-billed dinosaur with nasal passages that may have produced a swan-like honk and an elaborate head crest that could have been used as a resonating chamber to magnify the noises.

I’ll sing you a song of the dinoland. I am the best tooter on my block. Applying for Julliard next year. Although some of my best work may sound like farting noises, I think I just have a new sound that is too fresh for some. I am just misunderstood. But I promise if you let me mate with you, I will help watch the eggs 20% of the time.

— Carrie Levitt-Bussian, paleontology collections manager at the Natural History Museum of Utah

Oviraptor: A genus of small birdlike dinosaurs that lived in Mongolia during the late Cretaceous.

I am new to Mongolia and I'm looking for my partner in crime. I love to run, hunt, and currently working on some mating rituals — perhaps you can critique my mating dance and feather displays ;) I consider myself a feminist — I have no problem brooding eggs while you're out with your friends or at work! And yes, I do preen my feathers regularly!
— Eric Gorscak, paleontologist at the Field Museum of Natural History

Tyrannosaurus rex: Looks like my T. rex has some competition. (Who are we kidding? This dude is definitely out of my league.)
Fitness-minded apex predator with plenty of “rex” appeal looking for a tyrant lizard queen. Let's grab Triceratops tacos and watch the sun set over the Western Interior Seaway.
About me: love whiskey, travel, and working out. Biceps looking great but have some trouble with pushups. Can't run faster than 10 mph, but then again, neither can you. Eggs in the picture are my sister's.

The asteroid is coming so I'm not looking for anything serious. Basically just DTF (Down To Fossilize), but I'm cool to hang out and rub snouts afterwards. Not into vegetarians, smokers, drama, middle-age women. Please be under 5 tons.

13 feet tall because apparently that's important to you ladies...

— Sarah Werning, paleontologist at Des Moines University

Velociraptor: A genus of small, swift, probably feathered dinosaurs.
Looking for a “clever girl”? I'm small but fierce and on the hunt for a mate. Serious applicants only. Mess with me, and I'll bring out the claws.

— Brian Cleveland, copy editor for The Washington Post

Do you know an extinct species in need of someone special? Send us your best dinosaur dating profiles and we'll share them here.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #44
A Peculiar Star Is Doing Peculiar Things, Again

blogs.discovermagazine.com

[HR][/HR] Infrared: IPAC/NASA Ultraviolet: STScI (NASA)

There’s a star 1,300 light years away that has exhibited some of the strangest behavior ever seen: something dims 20 percent of its light, something that is beyond the size of a planet. It’s called KIC 8462852, but most people shorthand it Tabby’s Star, or Boyajian’s Star for its discoverer, Tabitha Boyajian.

Here’s the thing, though. Absolutely nobody knows why it’s dimming that much. It could be a massive fleet of comets or the debris of a planet. But it’s not giving off much infrared excess, which is a sort of “heat glow” from reflected starlight. And now, it seems to be dimming again, either helping or complicating the search for a solution.

Boyajian and co-investigator Jason Wright first put out the alert, hoping to garner observations from telescopes worldwide. They’re hoping at least one of telescope can grab spectra from the star to see what is causing the dimming.

CALL TO ACTION!! https://t.co/ll69iRowqi
— Tabetha Boyajian (@tsboyajian) May 19, 2017


So far the dimming is at 2-3 percent, meaning the transit of … something is just starting. Tabby’s Star has a dedicated telescope waiting to find such an event, so the big observation period could yield further clues to what’s occurring.

Ok, it’s time we tell you: some people think it’s aliens. The hypothesis, put forth by Wright, states that in the absence of a good hypothesis, all avenues must be explored, and that includes giant Dyson Swarm machines harnessing the power of the star. Gathering the spectra could help rule that out or bolster the case for that “all other avenues exhausted” scenario.

Here’s the thing, too: you can get in on the action. Amateur astronomers use smaller scopes to track the star, which is bigger and older than the Sun. It’s at around 12th magnitude in the direction of Cygnus. So get out there tonight and hunt for some aliens.

This article originally appeared in Astronomy.com.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #45
April marked the 388th month in a row that the global temperature was warmer than ave

blogs.discovermagazine.com

[HR][/HR]
To find a month when the global average temperature over the land and oceans was below average, you have to go all the way back to December 1984, according to the latest monthly analysis from the National Oceanic and Atmospheric Administration.

Including April 2017, that makes it 388 straight months in which the global temperature has been warmer than the 20th century average.

Like NASA’s independent analysis released earlier this week, NOAA finds that last month was the second warmest April in records dating back to 1880.

SEE ALSO: The heat goes on: this past April was second warmest in records dating back to 1880 — as were February and March

From NOAA’s monthly global climate report, released today:

Warmer-than-average temperatures during the month were observed across much of the world’s land surfaces, with the most notable warm temperature departures from average across the Northern Hemisphere higher latitudes, specifically across much of central and eastern Asia, Alaska and the eastern half of the contiguous U.S., where temperatures were 3.0°C (5.4°F) above average or higher. Several locations across Russia’s Far East had record warm temperatures during April 2017.

As the following map shows, there were some regions of the globe that experienced cooler than normal temperatures in April:

Most notable, according to NOAA, was northern Canada. Here temperatures were 3.6°–5.4°F below average or lower.

Even so, no land areas of the globe experience record cold in April.

Over the long run, human-caused global warming has loaded the dice, making unusual warmth much more likely than unusual cold. And that has had palpable impacts.

For example, between 1951 and 1980, much less than 1 percent of the Northern Hemisphere’s land areas experienced extreme heat during summer. By the first decade of the 20th century, extreme summertime heat typically was covering 10 percent of the land areas.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #46
What makes chocolate so deliciously melty in your mouth?

blogs.discovermagazine.com

[HR][/HR] Mmmmm…. chocolate! It’s not just the flavor that makes is so delicious, it’s also the rich texture in your mouth. But what factors lead to that smooth film that coats your mouth when you eat chocolate? If you think it’s simply melted cocoa butter, think again! According to this study, properties of both the chocolate and your saliva contribute to the “lubrication” of the chocolate as you chew it. These scientists measured the physical properties of molten chocolate mixed with either saliva or salty water (PBS) as well as “chocolate expectorated after chewing till the point of swallow” (yum!). They report that the cocoa butter, sugar particles, and saliva also play a role in developing the texture of chewed chocolate. We just hope the poor souls who were asked to spit out chocolate before swallowing were well compensated!

Lubrication of chocolate during oral processing.

“The structure of chocolate is drastically transformed during oral processing from a composite solid to an oil/water fluid emulsion. Using two commercial dark chocolates varying in cocoa solids content, this study develops a method to identify the factors that govern lubrication in molten chocolate and saliva’s contribution to lubrication following oral processing. In addition to chocolate and its individual components, simulated boluses (molten chocolate and phosphate buffered saline), in vitro boluses (molten chocolate and whole human saliva) and ex vivo boluses (chocolate expectorated after chewing till the point of swallow) were tested. The results reveal that the lubrication of molten chocolate is strongly influenced by the presence of solid sugar particles and cocoa solids. The entrainment of particles into the contact zone between the interacting surfaces reduces friction such that the maximum friction coefficient measured for chocolate boluses is much lower than those for single-phase Newtonian fluids.

The addition of whole human saliva or a substitute aqueous phase (PBS) to molten chocolate dissolves sugar and decreases the viscosity of molten chocolate so that thinner films are achieved. However, saliva is more lubricating than PBS, which results in lower friction coefficients for chocolate-saliva mixtures when compared to chocolate-PBS mixtures. A comparison of ex vivo and in vitro boluses also suggests that the quantity of saliva added and uniformity of mixing during oral processing affect bolus structure, which leads to differences in measured friction. It is hypothesized that inhomogeneous mixing in the mouth introduces large air bubbles and regions of non-emulsified fat into the ex vivo boluses, which enhance wetting and lubrication.”
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #47
Climate Change is Turning Antarctica Green, Say Researchers

Researchers in Antarctica have discovered rapidly growing banks of mosses on the ice continent's northern peninsula, providing striking evidence of climate change in the coldest and most remote parts of the planet. Amid the warming of the last 50 years, the scientists found two different species of mosses undergoing the equivalent of growth spurts, with mosses that once grew less than a millimeter per year now growing over 3 millimeters per year on average, (the link could be paywalled; alternative source below) the Washington Post reported on Thursday. From a report:

"Antarctica is not going to become entirely green, but it will become more green than it currently is," said Matt Amesbury, co-author of the research from the University of Exeter. "This is linking into other processes that are happening on the Antarctic Peninsula at the moment, particularly things like glacier retreat which are freeing up new areas of ice-free land -- and the mosses particularly are very effective colonisers of those new areas," he added. In the second half of the 20th century, the Antarctic Peninsula experienced rapid temperature increases, warming by about half a degree per decade. Plant life on Antarctica is scarce, existing on only 0.3% of the continent, but moss, well preserved in chilly sediments, offers scientists a way of exploring how plants have responded to such changes.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #48
Polar eye candy: check out this spectacular aerial photo of a Greenlandic fjord from

blogs.discovermagazine.com

NASA's Operation IceBridge


[HR][/HR] PLUS: a gallery of other compelling images from the mission

A fjord in southern Greenland, as seen during Operation IceBridge. (Source: NASA/John Sonntag)

I’m always looking for cool imagery to use here at ImaGeo, and today I stumbled on this photo.

It’s of a fjord in southern Greenland, taken during Operation IceBridge’s final flight of the 2017 Arctic campaign, on May 12, 2017. Fractured sea ice floats between the towering cliffs, with a glacier visible in the far distance at the head of the fjord.
NASA posted the image here today. I’ve done some modest processing to correct a weird color cast in the original.

As NASA puts it:
IceBridge, a six-year NASA mission, is the largest airborne survey of Earth’s polar ice ever flown. It will yield an unprecedented three-dimensional view of Arctic and Antarctic ice sheets, ice shelves and sea ice. These flights will provide a yearly, multi-instrument look at the behavior of the rapidly changing features of the Greenland and Antarctic ice.

Here are a few of my other favorite images taken during the multi-year project:
A lenticular cloud appears to hover above pressure ridges in the sea ice near Mount Discovery in Antarctica. (Photograph: Courtesy Michael Studinger/NASA)

I originally published the image above back in December of 2013. Shot by Michael Studinger of the IceBridge project, it’s a photograph of a phantasmagorical lenticular cloud hovering above the sea ice near Antarctica’s Mt. Discovery. In the middle distance is a jumble of jagged ice — a pressure ridge shoved up by the ever shifting sea ice.

SEE ALSO: Phantasm of the Antarctic Atmosphere

Here’s another IceBridge aerial photo from Antarctica:
The Transantarctic Mountains. (Source: NASA)

This image was photographed from a NASA P-3 airborne laboratory on Nov. 27, 2013, toward the end of the 2013 IceBridge Antarctic campaign. I love the multi-colored horizontal patterning of the rock intersected by snow-filled cracks.

[video=youtube_share;1FjXXMSfTxg]https://youtu.be/1FjXXMSfTxg"]http://blogs.discovermagazine.com/imageo/files/2017/05/Lance-1.png[/IMG[/video]The Norwegian research vessel R/V Lance, photographed during an Operation IceBridge flight on March 19, 2015. Click on the image to watch a video of the overflight. (Source: NASA)

Last but definitely not least is this photo of the Lance, a former sealing ship converted into a Norwegian research vessel. The crew of the Lance froze themselves into the Arctic sea ice north of Norway’s Svalbard archipelago starting in January of 2015 as part of the N-ICE2015 expedition.

They drifted with the ice taking a wide range of scientific measurements until June, when the floe to which they anchored the Lance broke up during the start of the warm season. The photograph was taken on March 19 during an IceBridge overflight. (Click on it for a video.)
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #49
Why Do Flamingos Stand on One Leg?

blogs.discovermagazine.com

[HR][/HR] A young flamingo demonstrates it’s passive, one-legged stance. (Credit: Rob Felt/Georgia Tech)

Flamingos are striking not only for their brilliant pink plumes, but for how they often stand on a single slender leg, even when asleep.

Now scientists find that standing on one leg may counter-intuitively require less effort for flamingos than standing on two. It’s a finding that could help lead to more stable legged robots and better prosthetic legs.

The One-Legged Problem

One prior explanation for the mystery of why flamingos stand on one leg is that it conserved body heat, as doing so places one less leg in the cool water where they feed. Another possibility that scientists raised over the years was that such a stance reduced muscle fatigue, but until now, researchers had not directly explored how much muscle activity the birds needed to balance on one leg.

Neuromechanist Lena Ting at Emory University and her team previously examined how people standing on one leg kept their balance, which led comparative neuromechanist Young-Hui Chang at the Georgia Institute of Technology to suggest investigating flamingos. Chang’s prior work in zoos helped them conduct research on the birds at Zoo Atlanta.

To help the scientists better understand flamingo anatomy, “we were very fortunate to get two frozen flamingo cadavers donated to us by another zoo,” Chang said. However, when driving the birds back to the lab, Chang recalled that he “had not anticipated how long their legs would be. My cooler was not big enough! I spent the whole drive back to Atlanta nervous about them thawing out. But I worried for nothing. The insulation from the feathers is amazing — if anything, I had trouble thawing them out for our study and had to use heat lamps for several hours to get them thawed out.”
Chang and Ting with their research subjects. (Credit: Rob Felt/Georgia Tech)

As the scientists dissected the cadavers, Chang recalled picking up a bird by its leg below the knee and finding the body kept “surprisingly stable. Even across wide angles of tilt — up to 75 degrees pitching the body backward — the knee and hip did not seem to budge.”
The flamingo cadavers showed that the birds could passively support their body weight on one leg without any muscle activity.

“That was the ‘Aha!’ moment when we knew we were on to something special,” Chang said. “If a dead flamingo could do it, then it is probably available for live birds to do.”

Surprisingly, cadaver flamingos could not stably hold a two-legged pose. This suggested it takes more active effort from muscles for the birds to stabilize a two-legged stance than a one-legged one, Ting said.

In addition, the researchers analyzed eight live juvenile flamingos as the birds stood on a plate that measured forces they generated on the ground. They found the flamingos swayed less as they became less active.

“When the birds closed their eyes and fell asleep on one leg, presumably with very little muscle activity, their postural sway was seven times lower compared to when they were very active,” Chang said.

Passive Balance

(Credit: Shutterstock)

These findings suggest that flamingos rely on passive mechanisms instead of active muscular effort to to support their body and control their balance as they stand on one leg.

“We still don’t know what anatomical mechanisms are engaged in the one-legged stance that allows for this, but as far as we can tell, it is related to the skeletal anatomy,” Chang said. “We would need to directly image the skeletal anatomy during this behavior — for example with X-rays — to really get at it, which is a direction for future research.”

The researchers suggest that a flamingo standing on one leg resembles a vertical, balanced, upside-down pendulum. Such a pendulum could in principle keep balance with little to no muscle activity. “I think the very idea that one-legged stance may cost less energy than standing on two legs is very exciting,” Chang said.

“It is counterintuitive, because we typically view standing on one leg as being very difficult and we tend to equate difficult things with consuming more energy.”

This research could help explain why many other bird species stand on just one leg, the researchers said.

“It may also have some important applications for inspiring the design of more efficient legged robots and powered prosthetic devices,” Chang said.

It remains uncertain whether flamingos stand on one leg to reduce muscle activity, save body heat, both, or neither. The researchers need more direct measurements of muscle activity and heat loss in live birds to further test these ideas, Ting said.

Chang and Ting detailed their findings online May 24 in the journal Biology Letters, but the research was carried out during Chang and Ting’s spare time, without direct funding.
“It was a labor of love — doing science simply for the sake of learning how nature works,” Chang said.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #51
Egyptian mummy DNA shows Mediterranean, Turkish and European ancestry

washingtonpost.com By Ben Guarino

[HR][/HR] Ancient Egyptians were an archaeologist's dream. They left behind intricate coffins, massive pyramids and gorgeous hieroglyphs, the pictorial writing code cracked in 1799. Egyptians recorded tales of royalty and gods. They jotted down life's miscellanies, too, as humdrum as beer recipes and doctor's notes.

But there was one persistent hole in ancient Egyptian identity: their chromosomes. Cool, dry permafrost can preserve prehistoric DNA like a natural freezer, but Egypt is a gene incinerator. The region is hot. Within the mummies' tombs, where scientists would hope to find genetic samples, humidity wrecked their DNA. What's more, soda ash and other chemicals used by Egyptian embalmers damaged genetic material.

A study led by researchers at the Max Planck Institute for the Science of Human History and the University of Tubingen in Germany managed to plug some of those genetic gaps. Researchers wrung genetic material from 151 Egyptian mummies, radiocarbon dated between Egypt's New Kingdom (the oldest at 1388 B.C.) to the Roman Period (the youngest at 426 A.D.), as reported Tuesday in the journal Nature Communications.

Johannes Krause, a University of Tubingen paleogeneticist and an author of the study, said the major finding was that “for 1,300 years, we see complete genetic continuity.” Despite repeated conquests of Egypt, by Alexander the Great, Greeks, Romans, Arabs and Assyrians — the list goes on — ancient Egyptians showed little genetic change. “The other big surprise,” Krause said, “was we didn't find much sub-Saharan African ancestry.”

The remains came from Abusir el-Meleq, an ancient Nile community in the middle of Egypt. From the mummies the scientists extracted bone, teeth and soft tissue samples. (Although Egyptian embalmers removed the brains of the deceased, the scientists wrote that “in most cases, non-macerated mummy heads still have much of their soft tissue preserved.”)

The hard samples yielded the most DNA, perhaps because the teeth and bones were protected by soft tissue or because the embalming processes left tougher material intact. After preparing the samples in a sterilized room in Germany, the researchers bathed the samples in UV radiation for an hour to minimize contamination.

Ancient Egyptians were closely related to people who lived along the eastern Mediterranean, the analysis showed. They also shared genetic material with residents of the Turkish peninsula at the time and Europe.

Given Egypt's location at the intersection of Africa, Europe and Asia, and the influx of foreign rulers, Krause said he was surprised at how stable the genetics seemed to be over this period. The scientists were particularly interested in the change in ruling class at the turn of the first millennium. First came the Hellenistic dynasty, in the aftermath of Alexander the Great’s conquests, from 332 B.C. to 30 B.C., and then Roman rule from 30 B.C. to about 400 A.D. And yet the genetics of the Abusir el-Meleq community appeared to be unperturbed by shifting politics.

The scientists compared these ancient genetics with those of 100 modern Egyptians and 125 modern Ethiopians that had been previously analyzed. If you ask Egyptians, they'll say that they have become more European recently, Krause said. “We see exactly the opposite,” he said.

It was not until relatively recently in Egypt's long history that sub-Saharan genetic influences became more pronounced. “In the last 1,500 years, Egypt became more African, if you want,” Krause said.

In their paper, the researchers acknowledged that “all our genetic data were obtained from a single site in Middle Egypt and may not be representative for all of ancient Egypt.” In the south of Egypt, the authors wrote, sub-Saharan influences may have been stronger.

This study left two gaps in the Egyptian timeline that Krause wants to fill, he said. It is not clear when the African gene flow, present in modern Egyptians, occurred. Nor could the study determine the origin of the Egyptians. “The other big question is, 'Where did the ancient Egyptians come from?' ” Krause said. To answer that, scientists will have to find genomes “back further in time, in prehistory.”

Read more:
This tiny fetus is the youngest ancient Egyptian mummy ever found
Happy anniversary, Ötzi: 25 years later, we’re still obsessed with the Iceman
New study on Ötzi the Iceman reveals humanity’s intimate affair with one microbe
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #52
Tree-Climbing Goats Keep the 'Desert Gold' Growing

blogs.discovermagazine.com
[HR][/HR] Goats grazing on an argan tree in southwestern Morocco. In the fruiting season, many clean argan nuts are spat out by the goats while chewing their cud. (Credit: H. Garrido/EBD-CSIC)

What do goats and squirrels have in common?

They both climb trees, of course. While squirrels live amongst the branches, goats, or at least those in arid regions, climb them for dinner. And that’s good for the goats, and the trees.

Scientists have discovered that the domesticated goats in southern Morocco benefit the argan trees, Argania spinosa, by spitting out the seeds of the fruits they eat, which helps in seed dispersal. Argan trees play an important role in southern Morocco acting as a barrier for the Sahara Desert, and providing locals with wood, food, medicine and other materials. Argan oil, sometimes called “desert gold,” has also emerged as an international luxury commodity, prized for its supposed anti-aging and conditioning properties for hair and skin.

Tree-climbing goats play a crucial role dispersing nuts from argan trees, ensuring the success of future generations of this valuable resource. But how, exactly, do these goats get the job done?

“For plants, there are well-known reproductive benefits with dispersing their seeds far from the maternal plant, including seed and seedling survival,” the scientists — Miguel Delibes, Irene Castaneda and Jose M. Fedriani — write in their paper published in May in the journal Frontiers in Ecology and the Environment.
Goats in southern Moracco climb argan trees to eat their fruit and leaves (Credit: imagebroker/Rex/Shutterstock)

Domesticated goats in grassy, temperate climates don’t climb trees because their food is literally under hoof. But in hot regions where grasses are patchy, like Africa, Mexico and some parts of Europe, goats leap upon green shrubs and squat in trees for sustenance.

In southern Morocco, goats climb 30 feet to the treetops. During autumn, when ground vegetation is scarce, three-quarters of their foraging time is spent in the ubiquitous argan trees.


Biologists are aware that ruminants (goats, cows, sheep, deer, etc.) spread seeds through defecation. But the paper’s authors say that is not the only way to sow them. They have chronicled seed spitting among sheep and deer in Spain. So it seemed likely to them that the Moroccan goats were spitting as well, especially because the seeds of argan trees are large and probably difficult to pass through the goats’ intestines.

Like other ruminants, goats have multiple stomachs. They regurgitate the contents of the rumen, the first stomach stop, and chew on it some more. During this process, the goats spit out the argan seeds —sometimes days later and far from the parent tree, the researchers discovered.

The message to other scientists studying animal seed dispersal? Don’t just study the dung.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #53
X-ray Blast Produces a 'Molecular Black Hole'

blogs.discovermagazine.com

[HR][/HR] The LCLS Coherent X-ray Imaging Experimental Station. (Credit: Nathan Taylor/SLAC)

When researchers want to take pictures of very small things, like individual molecules, they have to get creative.

When scales shrink to seemingly imperceivable levels, images must be captured using indirect techniques that record how the subject being photographed interacts with its environment. One way to do this is by observing how a beam of particles disperses around the object. Working backward, researchers can then infer what the object in question looks like.

Beam Power

The particle beams that do the heavy lifting for this kind of imaging require sophisticated equipment to create. At the SLAC National Accelerator Laboratory at Stanford University, their linear accelerator stretches out for two miles, focusing beams of charged electrons onto minuscule targets at extremely intense energies. In a paper published Tuesday in Nature, SLAC researchers observed peculiar behavior among atoms subjected to their X-ray beam, and they’re calling it a “molecular black hole.”

The Linac Coherent Light Source (LCLS) at SLAC is used to take pictures of organic molecules and biological processes that take place at scales of only a few atoms. A beam of electrons bounces off the molecules in a predictable way, giving researchers an idea of their structure. This happens in the brief instant before the sample is destroyed by the electron beam’s intense energy, something the researchers call “diffraction before destruction.” Understanding how the molecules behave as the beam passes through is critical to obtaining precise measurements.

From The Inside Out

Working with atoms of xenon and molecules containing iodine atoms, the researchers saw something unexpected occur. The beam ripped through the outer shells of the atoms and stripped away the innermost electrons, leaving a gaping void between the nucleus and the outer electrons. The overwhelmingly positive charge this created then sucked in all of the surrounding electrons with enough strength to not only gather its own electrons, but also steal them away from surrounding atoms.

As predicted by the laws of physics, this kind of electron theft doesn’t happen in nature because the forces involved are too great. Done fast enough, and with enough power, however, the naked nuclei overwhelm the grip of neighboring atoms and siphon off electrons, in a process, the researchers say, that is similar to a black hole consuming a star.

“When we have really, really intense X–rays like we do there’s enough X–rays that you knock out one electron and before there’s time for recombination you knock off another and then knock off another and so on and so forth,” says LCLS staff scientist and study co-author Sebastien Boutet. “What that ends up doing is stripping most of the inner shells and then that very highly charged molecule unexpectedly sucked in a bunch of electrons from neighboring atoms as a consequence.”

The molecular version doesn’t work the same way as a cosmic black hole, which relies on immense gravitational forces to suck in matter, but the observed effect is similar. Understanding how the beam interacts with atoms of this size, which often show up in their experiments, will help researchers fine-tune their images. The accelerator is currently undergoing an upgrade which will allow for a drastic increase in the number of beam pulses per second, expanding the machine’s imaging capacity.
The more precision researchers can achieve while working at scales of just a few hundred nanometers, the more they will see.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #54
3rd Gravitational Wave Detection Is About Much More Than Black Holes

blogs.discovermagazine.com
[HR][/HR] More than a year after detecting the first confirmed gravitational waves, researchers were busy at the Laser Interferometer Gravitational-wave Observatory (LIGO) in Livingston, La., upgrading the massive instrument. (LIGO lab)

Our sun was still dim. Waves crashed on martian beaches. Life was emerging on Earth.
That’s when the ghosts of two dead stars — black holes dozens of times more massive than our sun — merged in a far-off corner of the universe. In their final moments, these binary black holes were circling each other hundreds of times per second, as each one spun at 10 times that rate.

The rumbles of distant thunder from that collision reached Earth on Jan. 4 of this year, passing through the detector at the Laser Interferometer Gravitational-Wave Observatory (LIGO) in Hanford, Washington. Then, traveling at the speed of light, this wrinkle in space-time passed through LIGO’s second detector in Livingston, Louisiana, just a fraction of a second later.

The results were published Thursday in the journal Physical Review Letters.
Cosmic Forces

Gravity is the weakest among nature’s four fundamental forces. So only extreme cosmic events like supernovas, neutron stars and merging black holes can make detectable gravitational waves. The waves are so weak that they’d warp the distance between Earth and sun by just the width of a hydrogen atom. But as these waves pass through LIGO’s twin detectors, its enormous lasers can pick up on the truly tiny stretches and squeezes of space-time. You can think of it like a seismometer for measuring mini quakes in the cosmos’ gravitational fabric.

When LIGO gets a hit, the gravitational wave makes a characteristic signal that scientists’ call a “chirp” because of the sound it makes once translated into a format human ears can hear.

This was the third such detection since Albert Einstein first predicted gravitational waves a century ago as part of his general theory of relativity, or theory of gravity. Taken together, these observations form the first samples of a black hole census with far-reaching implications.

Before colliding, the binary black holes spotted earlier this year weighed in at 19 and 31 times our sun’s mass. After merging, the pair created a single black hole 49 times more massive than the sun. Einstein’s equations tell us that energy and mass are interchangeable. And so the missing solar mass worth of energy was radiated out across the universe as gravitational waves.

And with this detection, scientists for the first time think the two black holes might have been spinning in opposite directions. That could reveal clues about the lives of the stars that formed them. It’s possible that the two stars lived in a dense stellar cluster.
Before LIGO, astronomers didn’t know that so-called solar mass black holes, which form when stars die, could reach such extreme sizes.

This census can also help explain an enduring mystery in astronomy. Scientists have seen supermassive black holes that dominate entire galaxies, as well as small black holes that form after stars die. We even now know about so-called intermediate mass black holes weighing as much as thousands of suns. But how do these all form? Do many small black holes combine intro larger and larger behemoths? LIGO is just starting to piece together this puzzle.
Astrophysicist Stuart Aston monitors external vibrations on the LIGO test mass mirrors during an engineering run in November 2016. (Ernie Mastroianni/Discover)

More Than Black Holes

The latest signal took nearly 3 billion light years to reach Earth — twice as far off as the other detections. And because the gravitational wave arrived undiminished, it provides yet another proof of one of Einstein’s theories, showing that gravity travels at light speed.

“LIGO is going to be about a lot more than black holes,” says University of Wisconsin-Milwaukee (UWM) physicist Jolien Creighton, a veteran member of the detection team.
The observatory has forced open a new window on the universe, allowing scientists to hear from distant cosmic reaches — places where conventional telescopes come up empty. LIGO will bring new insights into everything from the heaviest elements on Earth to the nature of gravity itself.

LIGO’s next big breakthrough is expected to come from detecting collisions of binary neutron stars — the corpses of dead stars that pack a sun’s worth of mass into a city-sized sphere. These mergers happen at similar wavelengths to the black hole collisions LIGO’s already seen, and scientists once expected to see neutron stars first.
“This paper only reports on a few weeks worth of data, and we plan to run until August,” says Chad Hanna, a LIGO scientist from Pennsylvania State University. “We might still detect more events.”

So it’s possible that a binary neutron star merger could still be seen this year, or after the LIGO collaboration upgrades its instruments over the coming years. An upgrade over last summer didn’t increase the instrument’s sensitivity quite as much as scientists’ hoped.

“A lot of the elements we see on Earth were not formed in exploding stars but formed in the collision of binary neutron stars,” Creighton says. Humans are mostly made of typical star stuff like carbon and hydrogen, but other earthly elements with high atomic numbers, like gold, are suspected to have come from these more exotic events.
“Most of the gold we see in the solar system might have come from a binary neutron star collision that produced something like a Jupiter mass of gold and dispersed it in all directions,” Creighton says.

LIGO will detect neutron star mergers and send out an alert to the larger astronomy community, telling researchers to all point their telescopes to that region of sky and catch the event. The observations will let scientists test theories under conditions that could never be recreated in a lab.
Inside a stainless steel chamber, LIGO technicians examine the surface of one of the test mass mirrors that will reflect infrared laser light to measure the effect of gravity waves. After installation, all air was vacuumed from this chamber. (Mike Fyffe/LIGO lab)

Physicists also hope that more observations from LIGO will reveal new insights into gravity itself, as well as the theorized force-carrying particle called the graviton. It is to gravity what the photon is to light. Like the photon, scientists suspect it too has no mass. And this third LIGO gravitational wave detection helped constrain how big the graviton could possibly be. But new tests are on the horizon as well.

“I’m really excited about testing general relativity,” says UWM physicist Sarah Caudill, who works with the computer clusters that make LIGO detections possible. She suspects LIGO could reveal Einstein’s theory needs some small corrections.

“I think most people would be surprised if general relativity was 100 percent correct, but there’s no evidence that it’s not yet. Einstein created this theory 100 years ago and with no ability to observe gravitational waves, so for him to be 100 percent correct would be quite a feat.”
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #55
theatlantic.com Scientists Have Found the Oldest Known Human Fossils

theatlantic.com Scientists Have Found the Oldest Known Human Fossils

Ed Yong
8-10 minutes

[HR][/HR] Hundreds of thousands of years ago, around 62 miles west of what would eventually become Marrakesh, a group of people lived in a cave overlooking a lush Moroccan landscape. They rested there, building fires to keep themselves warm. They hunted there, sharpening stone tools to bring down animals. And they died there, leaving their bones behind in the dirt. At the time, there would have been nothing particularly notable about these cave-dwellers. They were yet more Homo sapiens, members of a nascent ape species that had spread across Africa. But in their death, they have become singularly important.

That cave is now called Jebel Irhoud, and bones of its former occupants have been recently unearthed by an international team of scientists. They mark the earliest fossilized remains of Homo sapiens ever found. Until now, that honor belonged to two Ethiopian fossils that are 160,000 and 195,000 years old respectively. But the Jebel Irhoud bones, and the stone tools that were uncovered with them, are far older—around 315,000 years old, with a possible range of 280,000 to 350,000 years.

It’s not just when these people died that matters, but where. Their presence in north Africa complicates what was once a tidy picture of humanity arising in the east of the continent. “What people, including myself, used to think was that there was a cradle of humankind in East Africa about 200,000 years ago, and all modern humans descend from that population,” says Philipp Gunz from the Max Planck Institute for Evolutionary Anthropology, who was involved in the new excavation. “The new finds indicate that Homo sapiens is much older and had already spread across all of Africa by 300,000 years ago. They really show that the African story of our species was more complex than what we used to think.”

“Humans had already migrated across the African landscape, and were evolving at a continental scale.”Jebel Irhoud rose to prominence in 1961, when miners turned the site into a quarry. They were looking for barite minerals, but to their surprise, they found a fossilized skull. Soon, they disinterred more bones: another skull, a child’s jaw, and fragments of arm bones and hips. From the start, these specimens were controversial. Their exact location was never recorded, which makes it very hard to work out their age. Scientists initially thought that they were the 40,000-year-old remains of Neanderthals—and were wrong on both counts. They’re much older, and they’re more likely to be Homo sapiens.

After those discoveries, Jebel Irhoud was neglected. But in 2004, Jean-Jacques Hublin from the Max Planck Institute for Evolutionary Anthropology led a team back to the site, clearing away decades’ worth of accumulated debris in a search for more fossils. And after a few seasons of digging, they found some—a partial skull, fragments of facial bones, a nearly complete adult jawbone, and other bits and pieces from at least five individuals.

These people had very similar faces to today’s humans, albeit with slightly more prominent brows. But the backs of their heads were very different. Our skulls are rounded globes, but theirs were lower on the top and longer at the back. If you saw them face on, they could pass for a modern human. But they turned around, you’d be looking at a skull that’s closer to extinct hominids like Homo erectus. “Today, you wouldn’t be able to find anyone with a braincase that shape,” says Gunz.

Comparison of the skulls of a Jebel Irhoud human (lleft) and a modern human (right) (NHM London)Their brains, though already as large as ours, must also have been shaped differently. It seems that the size of the human brain had already been finalized 300,000 years ago, but its structure—and perhaps its abilities—were fine-tuned over the subsequent millennia of evolution.

At Jebel Irhoud, the team also found several stone tools—small pieces of flint with sharp edges. Several of these had clearly been heated in the distant past, but not because their makers were deliberately burning the implements. More likely, “you can imagine that people were dropping stones on the ground, and later starting fires on top,” explains Shannon McPherron, an expert on stone tools who was involved in the new study.

The team exploited this incidental heating to date the tools. Over time, flint gradually builds up a small charge as it reacts to natural sources of radiation around it. That charge dissipates whenever it’s heated, before growing again. By testing the stones back in their lab, McPherron’s team could work out how much charge they had accumulated since they were last heated—which must have been when they were dropped in the caves. This technique, known as thermoluminescence, told them that the tools were roughly 280,000 and 350,000 years old.

Some of the Middle Stone Age stone tools from Jebel Irhoud (Mohammed Kamal / MPI EVA Leipzig)The team checked those dates by estimating the ages of the fossils. They first did that a decade ago, using the fossils collected in the 1960s, and they arrived at an age of 160,000 years. But that was based on imperfect guesses about the sediments in which the bones had been buried. This time, after taking careful readings from the site itself, the team could more accurately re-do their calculations. They got a much older date of 286,000 years, which matches well to the estimated age of the tools. “I think it’s a pretty tight picture,” says McPherron.

The new dates radically change the position of the Jehul Irhoud residents in the family tree of our species. Based on the earlier age estimates, scientists had always viewed these people as a primitive group of humans who were clinging on in North Africa while their more modern cousins were sweeping out of the East. “People thought that North Africa had nothing to do with modern human evolution, and that this was a relict population,” says Gunz. “Now we know that they’re close to the root of the Homo sapiens lineage.”

The new specimens cast fossils from other parts of Africa in a new light. For example, the so-called Florisbad skull, which was discovered in South Africa in 1932, is around 260,000 years old. Based on that old age, “people had a hard time accepting this as a member of Homo sapiens, but I think our work brings the Florisbad skull back into the discussion,” says Gunz. If the skull really did belong to a member of our species, it means that around 300,000 years ago, humans had already “migrated across the African landscape, and were evolving at a continental scale,” says Gunz.

The team have done a good job, says Erella Hovers from the Hebrew University of Jerusalem, but “whether this is a breakthrough in our understanding of human evolution, I’m not sure.” Others had already suggested that the origin of our species was tied to the dawn of the Middle Stone Age—a period between 250,000 and 300,000 years ago, when people went from making large stone hand-axes to smaller, lighter tools like awls and spear tips. Those lighter tools had already been found in other parts of Africa, so the Jebel Irhoud finds “support a hypothesis that has been around for a while,” Hovers says.

That’s true, says McPherron, but until now, the bones and stones were telling different tales. The stones were all over Africa by 300,000 years ago, and the fossils were apparently no older than 195,000. Were the tools even made by Homo sapiens or some other hominid? “We had a disjuncture,” he says. “We had a major transition in behavior but no biological transition to go with it. Jebel Irhoud fills that gap nicely.”

It’s possible that people spread all over Africa, aided by their new stone technology, which allowed them to kill large animals from a distance. Certainly the Sahara would have permitted their passage: At the time, it was a lush, green savannah and not the impassable desert of today. Alternatively, humans may have already spread throughout the continent, and regional innovators developed Middle Stone Age tools independently.

Regardless, the new finds are “a very important discovery,” says Zeray Alemseged from the University of Chicago. “They’re placed at a critical time period when the earliest members of our species could have evolved, and they’re critical for better understanding the patterns of physical and behavioral evolution [among humans] across the African continent. They confirm the pan-African nature of human ancestry.”
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #56
This worm grew a second head after a trip to space

engadget.com

It’s further confirmation that space travel permanently alters our bodies.


Swapna Krishna, @skrishna


SCIEPRO

There are all kinds of experiments going on aboard the International Space Station, but they all probably don't produce results as strange as this one. An article published today in the journal Regeneration details a recent experiment in which an amputated flatworm grew two heads -- twice.

Planarian flatworms are known to have extraordinary regenerative properties. They can regrow complex organs, including a central nervous system, from small pieces of their bodies. In order to study how space travel might affect these regenerative abilities, the scientists sent a group of worms up to the International Space Station; half were amputated, with their heads and tails cut off, and half were normal.

The worms stayed aboard the ISS for five weeks, after which they were observed for 20 months on Earth. This was when scientists noticed something very strange: One of the 15 amputated worms actually grew two heads. While this has occurred in fully Earth-bound worms, it's incredibly rare -- in 18 years of working with these worms, this specific research team has never encountered the phenomenon.

The team once again amputated the worm (seriously, what did this worm ever do to them?) and it grew another double head from the cut end. This has led the scientists to hypothesize that space travel has made some fundamental change to the worm's regeneration abilities.

It's not quite clear yet what implications this study has for humans, though it does support the idea that our bodies are permanently changed by space travel. These worms will help further examine the risks of space travel, but even more important than that, they may help scientists discover how to extend worms' regenerative properties to humans. After all, being able to regrow a limb would be pretty useful in deep space travel.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #57
The Maths of Life and Death: Our Secret Weapon in the Fight against Disease

scientificamerican.com

Christian Yates,The Conversation UK
[HR][/HR] The following essay is reprinted with permission from The Conversation, an online publication covering the latest research.

Maths is the language of science. It crops up everywhere from physics to engineering and chemistry – aiding us in understanding the origins of the universe and building bridges that won’t collapse in the wind. Perhaps a little more surprisingly, maths is also increasingly integral to biology.

For hundreds of years mathematics has been used, to great effect, to model relatively simple physical systems. Newton’s universal law of gravitation is a fine example. Relatively simple observations led to a rule which, with great accuracy, describes the motion of celestial bodies billions of miles away. Traditionally, biology has been viewed as too complicated to submit to such mathematical treatment.

Biological systems are often classified as “complex”. Complexity in this sense means that, due to the complicated interaction of many sub-components, biological systems can exhibit what we call emergent behaviour – the system as a whole demonstrates properties which the individual components acting alone cannot. This biocomplexity has often been mistaken for vitalism, the misconception that biological processes are dependent on a force or principle distinct from the laws of physics and chemistry. Consequently, it has been assumed that complex biological systems are not amenable to mathematical treatment.

There were some early dissenters. Famous computer scientist and World War II code-breaker Alan Turing was one of the first to suggest that biological phenomena could be studied and understood mathematically. In 1952 he proposed a pair of beautiful mathematical equations which provide an explanation for how pigmentation patterns might form on animals’ coats.

Not only was his work beautiful, it was also counter-intuitive – the sort of work that only a brilliant mind like Turing’s could ever have dreamed up. Even more of a pity, then, that he was so poorly treated under the draconian anti-homosexuality laws of the time. After a course of “corrective” hormone treatment, he killed himself just two years later.

An emerging field

Since then, the field of
has exploded. In recent years, increasingly detailed experimental procedures have lead to a huge influx in the biological data available to scientists. This data is being used to generate hypotheses about the complexity of previously abstruse biological systems. In order to test these hypotheses, they must be written down in the form of a model which can be interrogated to determine whether it correctly mimics the biological observations. Mathematics is the natural language in which to do this.

In addition, the advent of, and subsequent increase in, computational ability over the last 60 years has enabled us to suggest and then interrogate complex mathematical models of biological systems. The realisation that biological systems can be treated mathematically, coupled with the computational ability to build and investigate detailed biological models, has led to the dramatic increase in the popularity of mathematical biology.

Maths has become a vital weapon in the scientific armoury we have to tackle some of the most pressing questions in medical, biological and ecological science in the 21st century. By describing biological systems mathematically and then using the resulting models, we can gain insights that are impossible to access though experiments and verbal reasoning alone. Mathematical biology is incredibly important if we want to change biology from a descriptive into a predictive science – giving us power, for example, to avert pandemics or to alter the effects of debilitating diseases.

A new weapon

Over the last 50 years, for example, mathematical biologists have built increasingly complex computational representations of the heart’s physiology. Today, these highly sophisticated models are being used in an attempt to understand better the complicated functioning of the human heart. Computer simulations of heart function allow us to make predictions about how the heart will interact with candidate drugs, designed to improve its function, without having to undertake expensive and potentially risky clinical trials.

We use mathematical biology to study disease as well. On an individual scale, researchers have elucidated the mechanisms by which our immune systems battles with viruses through mathematical immunology and suggested potential interventions for tipping the scales in our favour. On a wider scale, mathematical biologists have proposed mechanisms that can be used to control the spread of deadly epidemics like Ebola, and to ensure the finite resources dedicated to this purpose are employed in the most efficient way possible.

Mathematical biology is even being used to inform policy. There has been research done on fisheries for example, using mathematical modelling to set realistic quotas in order to ensure we do not overfish our seas and that we protect some of our most important species.

The increased comprehension gleaned by taking a mathematical approach can lead to better understanding of biology at a range of different scales. At the Centre for Mathematical Biology in Bath, for example, we study a number of pressing biological problems. At one end of the spectrum, we try to develop strategies for averting the devastating effects of locust plagues comprising up to a billion individuals. At the other end, we try to elucidate the mechanisms that give rise to the correct development of the embryo.

Although mathematical biology has traditionally been the domain of applied mathematicians, it is clear that mathematicians who self-classify as pure have a role to play in the mathematical biology revolution. The pure discipline of topology is being used to understand the knotty problem of DNA packing and algebraic geometry is being used to select the most appropriate model of biochemical interaction networks.

As the profile of mathematical biology continues to rise, emerging and established scientists from disciplines across the scientific spectrum will be drawn to tackle the rich range of important and novel problems that biology has to offer.

Turing’s revolutionary idea, although not fully appreciated in his time, demonstrated that there was no need to appeal to vitalism – the god in the machine – to understand biological processes. Chemical and physical laws encoded in mathematics, or “mathematical biology” as we now call it, could do just fine.

This article was originally published on The Conversation. Read the original article.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #58
New evidence that all stars are born in pairs

phys.org
June 14, 2017 by Robert Sanders


Radio image of a very young binary star system, less than about 1 million years old, that formed within a dense core (oval outline) in the Perseus molecular cloud. All stars likely form as binaries within dense cores. Credit: SCUBA-2 survey image by Sarah Sadavoy, CfA Did our sun have a twin when it was born 4.5 billion years ago?

Almost certainly yes—though not an identical twin. And so did every other sunlike star in the universe, according to a new analysis by a theoretical physicist from UC Berkeley and a radio astronomer from the Smithsonian Astrophysical Observatory at Harvard University.

Many stars have companions, including our nearest neighbor, Alpha Centauri, a triplet system. Astronomers have long sought an explanation. Are binary and triplet star systems born that way? Did one star capture another? Do binary stars sometimes split up and become single stars?

Astronomers have even searched for a companion to our sun, a star dubbed Nemesis because it was supposed to have kicked an asteroid into Earth's orbit that collided with our planet and exterminated the dinosaurs. It has never been found.

The new assertion is based on a radio survey of a giant molecular cloud filled with recently formed stars in the constellation Perseus, and a mathematical model that can explain the Perseus observations only if all sunlike stars are born with a companion.

"We are saying, yes, there probably was a Nemesis, a long time ago," said co-author Steven Stahler, a UC Berkeley research astronomer.

"We ran a series of statistical models to see if we could account for the relative populations of young single stars and binaries of all separations in the Perseus molecular cloud, and the only model that could reproduce the data was one in which all stars form initially as wide binaries. These systems then either shrink or break apart within a million years."

A radio image of a triple star system forming within a dusty disk in the Perseus molecular cloud obtained by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. Credit: Bill Saxton, ALMA (ESO/NAOJ/NRAO), NRAO/AUI/NSF In this study, "wide" means that the two stars are separated by more than 500 astronomical units, or AU, where one astronomical unit is the average distance between the sun and Earth (93 million miles). A wide binary companion to our sun would have been 17 times farther from the sun than its most distant planet today, Neptune.

Based on this model, the sun's sibling most likely escaped and mixed with all the other stars in our region of the Milky Way galaxy, never to be seen again.

"The idea that many stars form with a companion has been suggested before, but the question is: how many?" said first author Sarah Sadavoy, a NASA Hubble fellow at the Smithsonian Astrophysical Observatory. "Based on our simple model, we say that nearly all stars form with a companion. The Perseus cloud is generally considered a typical low-mass star-forming region, but our model needs to be checked in other clouds."

The idea that all stars are born in a litter has implications beyond star formation, including the very origins of galaxies, Stahler said.

Stahler and Sadavoy posted their findings in April on the arXiv server. Their paper has been accepted for publication in the Monthly Notices of the Royal Astronomical Society.

Stars birthed in 'dense cores'
Astronomers have speculated about the origins of binary and multiple star systems for hundreds of years, and in recent years have created computer simulations of collapsing masses of gas to understand how they condense under gravity into stars. They have also simulated the interaction of many young stars recently freed from their gas clouds. Several years ago, one such computer simulation by Pavel Kroupa of the University of Bonn led him to conclude that all stars are born as binaries.

This infrared image from the Hubble Space Telescope contains a bright, fan-shaped object (lower right quadrant) thought to be a binary star that emits light pulses as the two stars interact. The primitive binary system is located in the IC …moreYet direct evidence from observations has been scarce. As astronomers look at younger and younger stars, they find a greater proportion of binaries, but why is still a mystery.

"The key here is that no one looked before in a systematic way at the relation of real young stars to the clouds that spawn them," Stahler said. "Our work is a step forward in understanding both how binaries form and also the role that binaries play in early stellar evolution. We now believe that most stars, which are quite similar to our own sun, form as binaries. I think we have the strongest evidence to date for such an assertion."

According to Stahler, astronomers have known for several decades that stars are born inside egg-shaped cocoons called dense cores, which are sprinkled throughout immense clouds of cold, molecular hydrogen that are the nurseries for young stars. Through an optical telescope, these clouds look like holes in the starry sky, because the dust accompanying the gas blocks light from both the stars forming inside and the stars behind. The clouds can, however, be probed by radio telescopes, since the cold dust grains in them emit at these radio wavelengths, and radio waves are not blocked by the dust.

The Perseus molecular cloud is one such stellar nursery, about 600 light-years from Earth and about 50 light-years long. Last year, a team of astronomers completed a survey that used the Very Large Array, a collection of radio dishes in New Mexico, to look at star formation inside the cloud. Called VANDAM, it was the first complete survey of all young stars in a molecular cloud, that is, stars less than about 4 million years old, including both single and mulitple stars down to separations of about 15 astronomical units. This captured all multiple stars with a separation of more than about the radius of Uranus' orbit—19 AU—in our solar system.

Stahler heard about the survey after approaching Sadavoy, a member of the VANDAM team, and asking for her help in observing young stars inside dense cores. The VANDAM survey produced a census of all Class 0 stars – those less than about 500,000 years old – and Class I stars – those between about 500,000 and 1 million years old. Both types of stars are so young that they are not yet burning hydrogen to produce energy.

Sadavoy took the results from VANDAM and combined them with additional observations that reveal the egg-shaped cocoons around the young stars. These additional observations come from the Gould Belt Survey with SCUBA-2 on the James Clerk Maxwell Telescope in Hawaii. By combining these two data sets, Sadavoy was able to produce a robust census of the binary and single-star populations in Perseus, turning up 55 young stars in 24 multiple-star systems, all but five of them binary, and 45 single-star systems.

Using these data, Sadavoy and Stahler discovered that all of the widely separated binary systems—those with stars separated by more than 500 AU—were very young systems, containing two Class 0 stars. These systems also tended to be aligned with the long axis of the egg-shaped dense core. The slightly older Class I binary stars were closer together, many separated by about 200 AU, and showed no tendency to align along the egg's axis.

A dark molecular cloud, Barnard 68, is filled with gas and dust that block the light from stars forming inside as well as stars and galaxies located behind it. These and other stellar nurseries, like the Perseus molecular cloud, can only be …more"This has not been seen before or tested, and is super interesting," Sadavoy said. "We don't yet know quite what it means, but it isn't random and must say something about the way wide binaries form."

Egg-shaped cores collapse into two centers
Stahler and Sadavoy mathematically modeled various scenarios to explain this distribution of stars, assuming typical formation, breakup and orbital shrinking times. They concluded that the only way to explain the observations is to assume that all stars of masses around that of the sun start off as wide Class 0 binaries in egg-shaped dense cores, after which some 60 percent split up over time. The rest shrink to form tight binaries.

"As the egg contracts, the densest part of the egg will be toward the middle, and that forms two concentrations of density along the middle axis," he said. "These centers of higher density at some point collapse in on themselves because of their self-gravity to form Class 0 stars."
"Within our picture, single low-mass, sunlike stars are not primordial," Stahler added. "They are the result of the breakup of binaries. "

Their theory implies that each dense core, which typically comprises a few solar masses, converts twice as much material into stars as was previously thought.

Stahler said that he has been asking radio astronomers to compare dense cores with their embedded young stars for more than 20 years, in order to test theories of binary star formation. The new data and model are a start, he says, but more work needs to be done to understand the physics behind the rule.

Such studies may come along soon, because the capabilities of a now-upgraded VLA and the ALMA telescope in Chile, plus the SCUBA-2 survey in Hawaii, "are finally giving us the data and statistics we need. This is going to change our understanding of dense cores and the embedded stars within them," Sadavoy said.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #59
Jupiter is the oldest planet in the Solar System

The king of the planets started taking shape almost as soon as the sun formed 4.6 billion years ago.



Mariella Moon, @mariella_moon


Lawrence Livermore National Laboratory

Jupiter's ancient name really is well-deserved: according to a new study, the king of the planets isn't just the largest in the Solar System, it's also the oldest. A team of researchers from Lawrence Livermore National Laboratory in California and the University of Munster in Germany have determined that Jupiter's core was already 20 times the size of Earth merely 1 million years after the sun took shape 4.6 billion years ago. Since newborn stars tend to release energy that blows away gas and dust for planet formation, the gas giant must have had to absorb materials very, very fast.

The team came to the conclusion after testing for the presence and abundances of molybdenum and tungsten isotopes in some iron meteorites that fell to Earth. They found that the meteorites contained components from two distinct reservoir of materials, thanks to the data from the molybdenum isotopes. One reservoir has material from a different star than ours that didn't make it to the other reservoir. The data from the tungsten isotopes, on the other hand, showed that the two pools of materials were separated for 2 to 3 million years. In addition, they've been separated as early as a million years into the formation of the solar system.

The team explained that "the most plausible mechanism to efficiently separate two disk reservoirs for an extended period is the accretion of a giant planet in between them." Yes, that gas giant is Jupiter, and while its formation slowed as the years went by, it kept growing and growing enough to create a permanent barrier between the two pools. The researchers now believe that it could also be the reason why there are no super-Earths near the sun, which are commonly found in other star systems. That means we could owe our existence to Jupiter, because who knows if and how life would flourish on Earth if it's too near other, more massive planets.
 

·
Banned
Joined
·
21,040 Posts
Discussion Starter #60
blogs.scientificamerican.com Jupiter Now Has 69 Moons

Caleb A. Scharf

Our local gas giant has two more natural satellites added to its roster


Credit: NASA, JPL-Caltech

The planet Jupiter is a beast: Three-hundred-and-seventeen times the mass of the Earth, mostly made of metallic hydrogen, and at the center of an astonishing collective of orbiting natural bodies.

In fact, Jupiter's satellites form a shrunken version of a full planetary system: from the tightly bound larger Galilean moons (orbiting in their Laplacian mean-motion resonances, akin to places like TRAPPIST-1) to the remarkable array of smaller moonlets that encircle this world out to more than 30 million kilometers.
These bodies circle Jupiter in anywhere from about 7 hours to an astonishing 1,000 days.

NASA's Juno spacecraft captured
of time lapse images of the large Galilean moons during the spacecraft's approach in early 2016:

(Credit:
)

Until recently the cataloged satellites totaled 67 in number. But only the innermost 15 of these orbit Jupiter in a prograde sense (in the direction of the planet's spin). The rest are retrograde, and are likely captured objects - other pieces of the solar system's solid inventory that strayed into Jupiter's gravitational grasp.

That population of outer moons is mostly small stuff, only a few are 20-60 kilometers in diameter, most are barely 1-2 kilometers in size, and increasingly difficult to spot.

Now astronomers Scott Sheppard, David Tholen, and Chadwick Trujillo have added two more; bringing Jupiter's moon count to 69.

These additions are also about 1-2 km in size, and were spotted in images that were part of a survey for much more distant objects out in the Kuiper Belt. Jupiter just happened to be conveniently close in the sky at the time. The moons are S/2016 J1 and S/2017 J1, and are about 21 million km and 24 million km from Jupiter.

By themselves these small satellites don't amount to much. But they are a vivid reminder of the sheer abundance of material out there in our solar system, and of Jupiter's royal gravitational status.
 
41 - 60 of 612 Posts
Top