As we get older, our memories start to fail us. The symptoms of this decline are clear, from losing track of house keys to getting easily muddled and confused. Many of these problems stem from a failure of working memory – the ability to hold pieces of information in mind, block out distractions and stay focused on our goals. Now, a team of American scientists has discovered one of the reasons behind this decline, and a way of potentially reversing it.

Our working memory depends on an area known as the prefrontal cortex or PFC, right at the front of the brain. The PFC contains a network of nerve cells called pyramidal neurons that are all connected to one another and constantly keep each other buzzing and excited – like a neural version of Twitter. This mutual stimulation is the key to our working memory. As we age, the buzz of the pyramidal neurons gets weaker, and information falls more readily from our mental grasp.

But this decline isn’t the fault of the neurons themselves. By studying monkeys, Min Wang from the Yale University School of Medicine has found ...

Click here to view the embedded video.

Yes, I will give it up and let go, just not yet. 

Source

The figure to the left is from a new paper in Science, When the World’s Population Took Off: The Springboard of the Neolithic Demographic Transition. It reports the findings from 133 cemeteries in the northern hemisphere in regards to the proportion of 5-19 year old individuals. When calibrated to period when agriculture was introduced into a specific region there seems to be a clear alignment in terms of a demographic transition toward a “youth bulge.” Why? A standard model of land surplus explains part of it surely. When farmers settle “virgin land” there is often a rapid “catch up” phase toward the Malthusian limit, the carrying capacity. Another possibility though is that sedentary populations did not need to space their offspring nearly as much as mobile hunter-gatherers. Whatever the details, the facts remain that the data do point to a shift in the age pyramid during this period. The author wonders as to the possible cultural implications of this. There is an a priori assumption that a young vs. old age profile in a society constrains its choices and channels its energies (e.g., think the “baby boom” generation in ...

Over the last year or so I’ve been devoting quite a bit of my time to exploring the origins and implications of a relatively new class of models known as Galileons. These may turn out to be nothing but mathematical curiosities, but while they’re still interesting I thought I’d try to explain what these theories are. This will be a little more technical than typical posts, but I’m hoping to get across the main reasons people are interested in these ideas even if the technicalities become a little much for some readers.

The resurgence of interest in extra dimensional models of particle physics and gravity during the last thirteen years has led to a number of novel approaches to cosmology, one of which is the fascinating idea of Dvali, Gabadadze and Porrati (DGP). In this picture, one begins by thinking of our four-dimensional world as residing on a brane floating in one extra dimension. The difference between this and other extra-dimensional models is that one imagines gravity as being described by a sum of the action for general relativity in 5d, and a 4d version just defined on the brane. This is rather technical, I know, but the main point is that gravity is described by an unusual but deceptively simple action. We, of course measure our world to be four-dimensional, and so the relevant question to ask of theories like this one is how the extra-dimensional physics manifests itself in the four-dimensional world.

As you might expect, this is a complicated issue. There is of course, the way in which the dynamics of four-dimensional gravity differ from that one would expect from pure General Relativity (GR). Furthermore, there are parts of the five dimensional gravity theory that manifest themselves as fields other than the graviton in four dimensions. One of these is a scalar field that can be interpreted as describing the bending of the brane in the extra dimension, and whose dynamics are bound up with those of the graviton in a complex way.

Now, surprisingly, one can learn quite a lot about this theory of modified gravity by doing away with the gravitational interactions all together! This so-called decoupling limit happens by taking the masses describing the strength of the gravitational interactions to infinity, while keeping a special combination of them – the one describing the strength of the self-interactions of the scalar field – constant. This limit is interesting because it isolates the dynamics of the scalar field, and nothing else. Given that what remains is a scalar field theory in four dimensions, one might guess that a host of possible terms would be allowed, and that their behavior would be well-understood; after all, scalar field theories have been studied for a long time and in great detail. However, it turns out that the symmetries of the DGP model, from which this theory originates, lead to an extremely restrictive form of the action – a scalar field theory with a single complicated derivative interaction, obeying the galilean symmetry under which the action is invariant when derivatives of the field are shifted by a constant vector.

I could go on to discuss only this theory, as a way to learn more about the DGP model. However, the realization that there existed a previously unconsidered symmetry of scalar field theories led Nicolis, Rattazzi and Trincherini to consider abstracting the symmetry, and asking what other terms may be allowed for scalar fields. And, remarkably, there turn out to only be five! In this abstracted scalar field theory we refer to these terms as the galileon terms, and to the scalar field itself as the Galileon. In a very nice paper, de Rham and Tolley later showed how these extra terms can also arise from their own actions for a brane living in a flat five-dimensional space. But for now, let’s just focus on the Galileons as interesting new four-dimensional scalar field theories.

I’m not going to write down the mathematical form of these terms here, but there are a number of properties they have that should illustrate why a number of people in the community have found them sufficiently interesting to warrant further study.

1. The Galileon terms involve higher derivatives, but there equations of motion are only second order in time, and hence they avoid some well-known proofs of instability that plague a lot of higher derivative systems.
2. There exists a range of energy scales over which the Galileon terms are important, and hence higher derivatives are important, yet quantum mechanical effects are irrelevant, and classical physics holds.
3. The Galileon terms are unrenormalized! Their coefficients pick up no modifications from quantum corrections arising from other Galileon terms!

This last feature hints at a number of possible applications in cosmology. For example, cosmic acceleration, either in the early or the late universe, typically requires scalar fields with dynamics that are finely tuned, and hence are easily perturbed by quantum corrections. There is therefore the possibility that Galileons may lead to a natural way to achieve such behavior.

A number of authors have begun exploring these possibilities, and my collaborators and I have our eyes on them also. Before that, however, we’ve been spending a significant amount of time trying to understand how the Galileon idea might fit into more general frameworks. We’ve explored multi-Galileon theories, that may arise from the types of gravity action I described earlier, but with more than a single extra dimension. And more recently we’ve expanded on the idea the such theories arise from branes floating in a flat five-dimensional spacetime to show how entirely new Galileon-like theories arise whenever we have the same types of actions for a brane floating in a more general bulk with a number of special symmetries.

Back in April, we held a mini-workshop at the Center for Particle Cosmology at Penn, attended by the majority (but not all, unfortunately) of people in the world working on these ideas. We left that meeting with a bunch of new ideas, working on which has occupied much of my summer. When they get worked out, I’ll tell you more about them.

It is much to early to know if the Galileon idea will help with any of the cosmological and particle physics problems it may be suited to. They’ve been turning up in a variety of surprising and fascinating ways even since our workshop, but that doesn’t necessarily mean anything. But whatever the answer is, we’re learning things, and the process is wonderful fun.

Around 02:00 UTC last night (July 30, 2011), a sunspot named Active Region 1261 erupted with a short solar flare, which was caught by NASA’s Solar Dynamics Observatory. Using Helioviewer I created a short video of the event:

[Make sure to set the resolution to at least 720p!]

Those bright regions are actually sunspots, which are dark at wavelengths our eyes can see, but are quite bright in the ultraviolet. Solar flares occur when the Sun’s magnetic field lines get twisted up. They store a lot of energy, and when tangled they can suddenly snap, releasing that energy. Astronomers classify flares by the energy released in X-rays, from Classes A,B, and C (weak) to M (moderate) to X (yikes!). This one was an M9, which is on the low end of the M class. Powerful, but probably not enough to affect us here 150 million kilometers away. If anything, there may be a stronger than normal aurora in a day or two.

The Sun’s activity waxes and wanes on a roughly 11 year cycle, and we’re on the upswing of Cycle 24. There was an unusually long quiet period after Cycle 23 and ...

Top picks

What a marine massacre looks like – great nuanced post by Rick Macpherson on shark-finning and what the reality is

“One of the animal kingdom’s greatest and most unappreciated symbioses.” Brandon Keim on fungus-farming beetles.

Does he have schizophrenia or is he simply Cockney? An amazing story from Vaughan Bell with a medical use for urbandictionary.com.

Personal genomics: no longer just for white folks. Great post form Daniel Macarthur

Kids are natural scientists. They too are bitter and frustrated by budget cuts.

What lurks at the deepest point of the Earth? We don’t know, but $10m goes to the person who finds out

US government proposes required consent for all human tissue research, citing Rebecca Skloot’s Immortal Life of Henrietta Lacks in the decision.

I’m now a freelancer. My new workplace.

“My god is this complexity ever going to end?” You can spend 37yrs studying spider dancing & barely scratch the surface.

Jennifer Frazer on the almighty prion (“the Rasputin of biology”) and why the humble lichen f**ks them up

“Our knowledge of the past is almost completely deodorized.” Fascinating piece on the smell of history, by Courteney Humphries

Do prey struggle when swallowed whole, or do ...

UPDATE:  Solved by Rob at 12:55 CDT

So, feeling witty today, are we?

I have a riddle I think you might enjoy.  It may seem a bit of a challenge on first glance, but I have the utmost confidence in your abilities.  No, really; I’m being serious.  What?  You don’t trust me to be sincere?  Moi?

For today we’re back in reality, so take a few deep breaths to get some oxygen to those caffeine-infused neurons you’re carrying around, and let’s see how you like this one:

Pretty picture, isn't it?

It’s not there.

This is a modern discovery.

It’s true nature was unknown for 20 years.

Image by Jesse Pavlick

It took an Einstein to figure this one out.

This has something in common with Barnard’s star.

We’ve watched what this does over 3 billion times.

A gorgeous floor clock.

There you have it.  I’ll be waiting in the comment section for your answer to the riddle.

Run away! Run away! It's SpiderBart!

Last month I contemplated the staggering diversity of microbes in my bellybutton–an experience made possible by my participation in a survey of microbiome diversity carried out by scientists at North Carolina State University. At the time, I thought I was quite the host. I was informed there were 53 species living in my navel, some of which had never been seen on skin before and some of which were altogether new to science. I was even informed that I was a “wonderland.”

Well, the project is moving forward at quite a clip, and the scientists are starting to push more of their data online. Here you can see the species from the first 60 volunteers they’ve studied. The lists are coded by number–I’m B944. I appear to have lost a species so I’m down to 52. And 52 is, I’m seeing, nothing to blog home about. So far, the diversity champion is the anonymous owner of bellybutton B1288. 107 species! Now that’s a wonderland….

I’ve mentioned in the past that the International Space Station is easily visible to the unaided eye when it passes through the sky. That means it’s not hard to get pictures of it. Unless you have pretty fancy equipment you’ll only see it as a bright dot of light, but that’s still pretty cool, and worth a try.

This shot of the ISS is from a webcam at the Tellus Museum of Science in Georgia, which is part of the All Sky Fireball Network. That’s a collection of four cameras in the US southeast looking for bright meteors; the idea being that if one is caught by more than one camera the path can be calculated in three dimensions, and a location of any potential meteorite found.

The webcam shot of the ISS was happenstance, but inevitable; when you have a camera that looks up all the time it’ll get a shot of the space station eventually! But you don’t have to guess; go Heavens Above, enter your latitude and longitude (which you can get from Google Earth) and it will tell you just when interesting things ...

The twisted ring around the galactic center. Larger versions linked below. Images: ESA/NASA/JPL-Caltech

If you are having trouble visualizing the ring click the image.  You can get larger versions of the images at the link below and I recommend you do so, they are really good.

From the ESA Herschel Space Observatory site (via Caltech).

New observations from the Herschel Space Observatory show a bizarre, twisted ring of dense gas at the center of our Milky Way galaxy. Only a few portions of the ring, which stretches across more than 600 light-years, were known before. Herschel’s view reveals the entire ring for the first time, and a strange kink that has astronomers scratching their heads.
“We have looked at this region at the center of the Milky Way many times before in the infrared,” said Alberto Noriega-Crespo of NASA’s Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. “But when we looked at the high-resolution images using Herschel’s sub-millimeter wavelengths, the presence of a ring is quite clear.” Noriega-Crespo is co-author of a new paper on the ring published in a recent issue of Astrophysical Journal Letters.
The Herschel Space Observatory is a European Space Agency-led mission with important NASA contributions. It sees infrared and sub-millimeter light, which can readily penetrate through the dust hovering between the bustling center of our galaxy and us. Herschel’s detectors are also suited to see the coldest stuff in our galaxy.
When astronomers turned the giant telescope to look at the center of our galaxy, it captured unprecedented views of its inner ring — a dense tube of cold gas mixed with dust, where new stars are forming.
Astronomers were shocked by what they saw — the ring, which is in the plane of our galaxy, looked more like an infinity symbol with two lobes pointing to the side. In fact, they later determined the ring was torqued in the middle, so it only appears to have two lobes. To picture the structure, imagine holding a stiff, elliptical band and twisting the ends in opposite directions, so that one side comes up a bit.
“This is what is so exciting about launching a new space telescope like Herschel,” said Sergio Molinari of the Institute of Space Physics in Rome, Italy, lead author of the new paper. “We have a new and exciting mystery on our hands, right at the center of our own galaxy.”
Observations with the ground-based Nobeyama Radio Observatory in Japan complemented the Herschel results by determining the velocity of the denser gas in the ring. The radio results demonstrate that the ring is moving together as a unit, at the same speed relative to the rest of the galaxy.
The ring lies at the center of our Milky Way’s bar — a bar-shaped region of stars at the center of its spidery spiral arms. This bar is actually inside an even larger ring. Other galaxies have similar bars and rings. A classic example of a ring inside a bar is in the galaxy NGC 1097, imaged here by NASA’s Spitzer Space Telescope. http://www.spitzer.caltech.edu/images/2687-ssc2009-14a-Coiled-Creature-of-the-Night The ring glows brightly in the center of the galaxy’s large bar structure. It is not known if that ring has a kink or not.
The details of how bars and rings form in spiral galaxies are not well understood, but computer simulations demonstrate how gravitational interactions can produce the structures. Some theories hold that bars arise out of gravitational interactions between galaxies. For example, the bar at the center of our Milky Way might have been influenced by our largest neighbor galaxy, Andromeda.
The twist in the ring is not the only mystery to come out of the new Herschel observations. Astronomers say that the center of the torqued portion of the ring is not where the center of the galaxy is thought to be, but slightly offset. The center of our galaxy is considered to be around “Sagittarius A*,” where a massive black hole lies. According to Noriega-Crespo, it’s not clear why the center of the ring doesn’t match up with the assumed center of our galaxy. “There’s still so much about our galaxy to discover,” he said.
An abstract and full PDF of the Astrophysical Journal Letters study is online at http://arxiv.org/abs/1105.5486.
Herschel is a European Space Agency cornerstone mission, with science instruments provided by consortia of European institutes and with important participation by NASA. NASA’s Herschel Project Office is based at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. JPL contributed mission-enabling technology for two of Herschel’s three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the United States astronomical community. Caltech manages JPL for NASA.

Well this is it, NASA’s human spaceflight becomes a memory after the landing of Atlantis this morning. Thousands of people gave all they had to the various programs over the years and now their efforts are essentially being tossed away but those efforts were not for naught and they will be remembered by some of us. some would say well there are the other missions in the works, the sad truth is the human program was probably the toughest nut to crack and the rest could be cancelled quite easily. Fortunately there are other countries out there with the foresight to continue to build their programs.

We are hanging our hats on private industry and they will not disappoint I am sure as long as the economy doesn’t preclude it.

So hopefully this UStream video link works and we can watch live, I will admit I will be watching on NASA TV as well.

Live streaming by Ustream

Pluto and the now FOUR moons. Click for larger. Credit: NASA, ESA, and M. Showalter (SETI Institute)

Cool, Pluto might be “just” a dwarf planet but it sports four moons and thanks to Hubble we know it. I am amazed even Hubble could spot the tiny moon P4.

The short version from Hubblesite (click for the Full Story and more images):

These two images, taken about a week apart by NASA’s Hubble Space Telescope, show four moons orbiting the distant, icy dwarf planet Pluto. The green circle in both snapshots marks the newly discovered moon, temporarily dubbed P4, found by Hubble in June. P4 is the smallest moon yet found around Pluto, with an estimated diameter of 8 to 21 miles (13 to 34 km). By comparison, Pluto’s largest moon Charon is 746 miles (1,200 km) across. Nix and Hydra are 20 to 70 miles (32 to 113 km) wide. The new moon lies between the orbits of Nix and Hydra, two satellites discovered by Hubble in 2005. P4 completes an orbit around Pluto roughly every 31 days.

The new moon was first seen in a photo taken with Hubble’s Wide Field Camera 3 on June 28, 2011. The sighting was confirmed in follow-up Hubble observations taken July 3 and July 18. P4, Nix, and Hydra are so small and so faint that scientists combined short and long exposures to create this image of Pluto and its entire moon system. The speckled background is camera “noise” produced during the long exposures. The linear features are imaging artifacts. The Hubble observations will help NASA’s New Horizons mission, scheduled to fly through the Pluto system in 2015. Space Telescope Science Institute director’s discretionary time was allocated to make the Hubble observations.

Dawn captured this image of Vesta yesterday, July 17:

NASA/Dawn at about 9,500 miles

PASADENA, Calif. — NASA’s Dawn spacecraft has returned the first close-up image after beginning its orbit around the giant asteroid Vesta. On Friday, July 15, Dawn became the first probe to enter orbit around an object in the main asteroid belt between Mars and Jupiter.

The image taken for navigation purposes shows Vesta in greater detail than ever before. When Vesta captured Dawn into its orbit, there were approximately 9,900 miles (16,000 kilometers) between the spacecraft and asteroid. Engineers estimate the orbit capture took place at 10 p.m. PDT Friday, July 15 (1 a.m. EDT Saturday, July 16).

Vesta is 330 miles (530 kilometers) in diameter and the second most massive object in the asteroid belt. Ground- and space-based telescopes have obtained images of Vesta for about two centuries, but they have not been able to see much detail on its surface. “We are beginning the study of arguably the oldest extant primordial surface in the solar system,” said Dawn principal investigator Christopher Russell from the University of California, Los Angeles. “This region of space has been ignored for far too long. So far, the images received to date reveal a complex surface that seems to have preserved some of the earliest events in Vesta’s history, as well as logging the onslaught that Vesta has suffered in the intervening eons.”

Vesta is thought to be the source of a large number of meteorites that fall to Earth. Vesta and its new NASA neighbor, Dawn, are currently approximately 117 million miles (188 million kilometers) away from Earth. The Dawn team will begin gathering science data in August. Observations will provide unprecedented data to help scientists understand the earliest chapter of our solar system. The data also will help pave the way for future human space missions.

NASA - Check out the enlargement

Click here to view the embedded video.

Atlantis has undocked from the ISS marking a milestone in extinguishing the US human space program.  It’d  kind of ironic really, considering tomorrow (July 20) is the anniversary of the first manned moon landing.  Don’t forget to watch for the pair in the skies over head, you will never get another look at them together.  You can find when to look by checking Heavens Above or Spaceweather.com

Oh by the way, the place I posted about last week (and they donated the riddle prize), Headlineshirts is running a sale on a moon themed tee shirt called the Moon Flamingo , it’s only $ 2.00 with the code SPACEBOOTS.

I have posted on the existence of blonde hair amongst some Melanesians before. There are natural chemical treatments as well as extreme malnutrition which can result in blonde hair in dark skinned people. The latter seems unlikely from the photos I’ve seen (the lightening of hair due to lack of food has been reported in African refugee camps). In regards to the former I’m confused as to why chemical treatments would be common among Oceanian people as disparate as Solomon Islanders and central desert Australian Aborigines, and yet not among many other east Eurasian populations.

In any case, in response to this comment below on Negrito appearance, I started using google images, and I stumbled upon something strange. In my Malaysian Negrito sample there’s a division between two ethnic groups, Kensiu and Jehai. The Kensiu have hardly any Austro-Asiatic or Austronesian admixture compared to the Jehai. When I looked for images of the Kensiu I came upon on this page, which seems to relate an experience of an aid worker in an isolated Malaysian village. The inhabitants were ethnically diverse, some Malays, but indigenous Negritos a well. Well, it turns out that some of ...

by Jon Winsor

The Washington Examiner’s Ron Arnold is a bit perturbed that anyone is calling out the misinformation campaign about the “incandescent light bulb ban.” So he’s trying to turn the tables:

Time claims: “Philips and other manufacturers are already making more efficient incandescent bulbs.” That’s short of an outright lie but it’s way beyond hogwash. What Philips is making is halogen lamps, which are incandescent alright, but complex electronic circuit devices about as close to an ordinary incandescent lamp as a third-degree burn, which you can efficiently obtain from a halogen lamp.

To all appearances it works just like an ordinary incandescent bulb, and looks almost the same (see upper right). If there are any weird, “complex electronic circuit devices” (CECDs), you can’t tell by looking at it.

Arnold continues:

Philips’ 36-page “product information” manual, shows on page 23 that their “Clickline” halogen lamp operates at temperatures as high as 480 degrees Fahrenheit (on the contacts), and 1,650 degrees F. (on the bulb). All aren’t that hot, but not by much. By the way, aluminum melts at 1,220.58 degrees Fahrenheit.

1,650 degrees F on the bulb? Melts Aluminum? Now you’ve got me scared. Only, not:

Amos Zeeberg, the person you should pester (hopefully ineffectually!) when I’m not being nice to you in the comments, has an interesting opinion piece up lambasting the Shuttle program. Here are the numbers which jumped out at me (I knew the broad outlines, but nice to have precise numbers):

The most important thing to realize about the space shuttle program is that it is objectively a failure. The shuttle was billed as a reusable craft that could frequently, safely, and cheaply bring people and payloads to low Earth orbit. NASA originally said the shuttles could handle 65 launches per year; the most launches it actually did in a year was nine; over the life of the program, it averaged five per year. NASA predicted each shuttle launch would cost $50 million; they actually averaged $450 million. NASA administrators said the risk of catastrophic failure was around one in 100,000; NASA engineers put the number closer to one in a hundred; a more recent report from NASA said the risk on early flights was one in nine. The failure rate was two out of 135 in the tests that matter most.

To take the intangible value of human life out of ...

Male organ and economic growth: does size matter?

“This paper explores the link between economic development and penile length between 1960 and 1985. It estimates an augmented Solow model utilizing the Mankiw-Romer-Weil 121 country dataset. The size of male organ is found to have an inverse U-shaped relationship with the level of GDP in 1985. It can alone explain over 15% of the variation in GDP. The GDP maximizing size is around 13.5 centimetres, and a collapse in economic development is identified as the size of male organ exceeds 16 centimetres. Economic growth between 1960 and 1985 is negatively associated with the size of male organ, and it alone explains 20% of the variation in GDP growth. With due reservations it is also found to be more important determinant of GDP growth than country’s political regime type. Controlling for male organ slows convergence and mitigates the negative effect of population growth on economic development slightly. Although all evidence is suggestive at this stage, the `male organ hypothesis’ put forward here is robust to exhaustive set of controls and rests on surprisingly strong correlation”

Bonus quotes from the main text:

“Only stylized explanations ...

Well, today is certainly shaping up to be "jaw-dropping pictures of Atlantis day"! How so? Well, I already posted the stunning image of the Orbiter’s descent as seen from space, and just the other day I mentioned how I was hoping Nathanial Burton-Bradford would make more 3D images… so guess what? Get out your red/cyan glasses: here’s the plasma-lit descent of Atlantis as seen from space in 3D!

Wow! The ISS astronauts took several pictures of the Orbiter as it descended. Nathanial took two of them from NASA’s spaceflight gallery and combined them to make this anaglyph. If you click between the two original shots (here and here) you can see they were taken a few seconds apart; the motion of the stars, the Earth, and the plasma plume change a little bit (click between them rapidly and you’ll actually get a feel of the motion. Weird).

The other pictures at the NASA page are amazing as well. Funny, when I first heard of the plasma picture I poked around NASA’s site and couldn’t find any other images, but clearly I either missed them or they weren’t up ...

1) Post from the past: Religion & IQ.

2) Weird search query of the week: “picture of john gillespie japanese sports.”

3) Comment of the week, in response to “Neanderthal-human mating, months later….”:

Humans mating with Neanderthals? Hmmm, could this be the first evidence of alcohol use?

4) And finally, your weekly fluff fix: