Thinking like a human, a computer program falls for similar illusions

If you designed a computer program to make decisions like a human, wouldn't you expect it to make human mistakes?

At the University College in London, researchers made a computer program that acquired knowledge the same way humans do, from experience, trial and error. The computer studied a series of gray-scale images. Its job was to judge the lightness of the shade at the center of each image. As the computer made its choices, it changed its decision technique depending on whether its previous decision was right or wrong.

Not surprisingly, when looking at certain gray-scale contrasts, the computer program fell for the same optical illusions that trick most of us. For example, when it studied a light object on a darker background, it predicted that the shade of object was lighter than it really was. Dark objects on lighter backgrounds similarly fooled the program. The computer also fell for 'White's Illusion', a pattern in which the same shade of gray is usually predicted by humans to be two different shades (see link for illustration).

The program points out the difference between hard-wired, computer-coded decision making and the more human process of making judgements based on experience. Human minds are not wired for accuracy, they're wired to find what's useful. link

Birds likely see magnetic fields

Imagine if your eyes could see the Earth's magnetic field around you. It's likely that migratory birds can do just that.

We've known that migratory birds use the Earth's magnetic field to navigate during their migrations. In order to sense magnetic fields, birds use their eyes and the part of the brain that processes vision.

Recently, scientists observed the jumping behavior of garden warblers under different colors of light. It was observed that only certain colors of light threw off the birds' navigation system. This hinted that vision played a role. In further studies, brain activity was monitored while the birds where in migratory mode. The neuron pathways for sensing vision and magnetism were found to be one in the same. link audio

It's a comet - it's an asteroid - it's both

It used to be an asteroid was an asteroid and a comet was a comet. Now, astronomers realize, the line's getting blurry.

In 1999, the Heliospheric Observatory (SOHO) spacecraft spotted an object (later dubbed 'P/2007 R5') passing close to the Sun. The object was assumed to be a comet, because it was passing the sun, and that's what comets are known to do. What puzzled some scientists was that P/2007 R5 did not have classic comet features such as a tail and a coma – the cloud of gas and dust that surrounds a comet's body, or nucleus. The tail and coma are created when the Sun's heat vaporizes frozen water and carbon dioxide on the comet, and blasts a brightly illuminated cloud of dust off the comet's surface. Without these features, P/2007 R5 would be better classified as an asteroid. Asteroids traditionally do not contain high enough quantities of solid carbon dioxide and water ice to make such a display.

When SOHO spotted P/2007 R5 swinging by the Sun again in 2003, scientists officially designated it as a short-period comet.

Pesky little P/2007 R5 appeared near the Sun again in September 2007. It still didn't have the classic comet features, but on this passage near the Sun, when it was just 15% of Mercury's distance from the star, it brightened by a factor of a million and faded again. These brilliant flashes are common for comets, but not for asteroids.

Based on its orbit, P/2007 R5 is likely a comet from the Kuiper belt, a reservoir of icy comets and asteroids that orbit the Sun way out beyond the orbit of Neptune. Most of P/2007 R5's surface ice was probably baked off during previous passes near the Sun, so that it now shows little to no tail or comma when it feels the Sun's heat.

So, is it a comet or is it an asteroid? Scott Sheppard of the Carnegie Institution of Washington in DC says, "There's probably not a sharp cutoff. Comets probably have a lot of rock in them and asteroids probably have a lot of ice in them as well." link

Bacteria cultured in space are more deadly

It turns out that a few bacteria can really ruin your space flight. That's why NASA quarantines astronauts several days before their launch.

The National Academy of Sciences reported that bacteria exposed to the microgravity of space are considerably more deadly than their earthbound relatives. During last year's space shuttle Atlantis mission, astronauts brought aboard (on purpose) infectious Salmonella bacteria to see how they are affected by microgravity. When the space-tourist bacteria returned to Earth, they were injected into mice. Mice exposed to space bacteria were three times more likely to die from the Salmonella infection than the control mice, which were injected with earthbound Salmonella.

The most likely explanation for this dwells along the outer cell walls of the bacteria. It is thought that microgravity reduces fluid shear - the movement of liquid around the bacterium cells. Low fluid shear conditions are what the cells experience when they are in the human body. It was also observed that the low fluid shear stimulated the expression of the gene Hfq, which scientists are now fingering as the key to Salmonella's increased strength.

Couple microgravity's affect on bacteria with the fact that microgravity is also known to weaken the human immune system, and it creates a perfect storm for bacteria to attack space travelers. link

Blurring the line between algorithm and judgment

A NYTimes science columnist has eloquently mused on the input-feedback dynamic between cyberspace and its users. "As you sit with your eHarmony spouse watching the movies Netflix prescribes, you might as well be an avatar in Second Life. You have been absorbed into the operating system." link
(If you don't want to register for NYT free content, go to http://www.bugmenot.com/)

Why our cells regenerate the hard way

We lose billions of cells from our body everyday. It's natural to lose them, and luckily, we can naturally replace them. But when our cells regenerate, but they don't do it the easy way. The easy way would be for similar cells in the location to divide and replicate themselves to fill in for their lost neighbors. That would be a very fast and energy-efficient way of regenerating. But that's not the way it works, as summarized in a new report in Nature.

When dead cells are replaced, they are replaced from scratch. Each kind of cell in the body has its own dedicatied set of stem cells. To keep up with the need for replacement cells, stem cells act as the seeds from which new cells for that part of the body are sprung. By dividing, the stem cells initiate a series of cell generations, each new generation more speciallized than the one before it, until the just the right replacement cell is produced. This process takes a lot more energy and time than a single cell division.

Building replacement cells from scratch is safer for the body; it guarentees that replacement cells will not have the mutations of the cells from which they divided. Why is this safer? If the dividing cell was deceased, or if it were a cancer cell, then deceased cells would divide and quickly multiply beyond the organism's control.

Futhermore, if our cells were to regenerate by a single cell division, single organisms would evolve as they aged. For example, consider a frog genetically built for a cool, wet environment that moves to a hot, dry environment. As the cells of this frog are naturally replaced over time, the cells that are better suited for dry heat will out-complete the others. And with each generation of new cells, the whole frog would evolve towards the hot, dry environment. Within its single lifespan, this organism would do what is not possible: evolve into a very different one. A species cannot evolve in one generation; it must evolve over a long series of generations.

So, for an organism to make a replacement cell, it must be built from scratch from stem cells; it cannot make cheap copies of ready-made cells.

Interestingly, there is an exception to this rule, found in cells of the immune system. The cells of an organism's immune system must evolve within the organism's lifespan. Take our frog for example: when the frog's immune system encounters a decease it has never handled before, immune cells capable of fighting the decease can directly divide themselves to increase their numbers. It does the frog no good if the frog's descendants' evolve to fight the decease. The frog's immune cells must evolve during the frog's lifetime, or the frog won't stand a chance against the new decease. Does this mean that cells of the immune system are more vulnerable to decease, given that deceased immune cells are can divide and spread themselves? Yes. This is why deceases that attack the immune system are so deadly. link

Martian surface water: none to be found

Finding liquid water on Mars has been a frustrating endeavor. We know that the poles are covered with ice, but several satellite missions have failed to find water flowing on the surface of the red planet. This month's journal Science describes the latest information from the first 100 days of the mission of the Mars Reconnaissance Orbiter (MRO). Hoping that the orbiter would identify waterfront landing sites for future rovers, scientists were disappointed to find that the virtually all of the Mars surface is dry. The formations once thought to be carved out by flowing water have been formed by lava flows. Dry areas thought to be riverbeds and former ocean floors are covered with volcanic rock. link

Things could always be worse

Think the environment in your area is bad? Yesterday, National Geographic reported the 10 most polluted places in the word, as named by the Blacksmith Institute. No sites in the US made the list, which includes several mining towns and Chernobyl. link

A rose is not a rose

The old saying goes, "a rose is a rose is a rose." Scientists, however know otherwise. Two humans can describe and react to the same smell quite differently. In a recent study at Rockefeller University in NY, some human subjects found the compound androstenone to be appealing and sweet, others found it to be foul and offensive, and others could not smell it at all. Going on a hunch, the scientists examined each subjects' genetic code, and found that how the subjects perceived androstenone depended on a single gene. This is one step in unravelling the links between our genetic code and our senses. link audio link

Waking a sleeping red giant

Better get your stuff done. Time's running out. Five-billion years from now, our sun will live out it's current stage of life. Having turned all the hydrogen in it's core into helium, it's outer layers of hydrogen will collapse into the center. The sun will become a red giant. In the process, it's core will heat and expand, it's radius will grow to 100 times it's size, and anything in the way, including Mercury and Venus, will be obliterated. But, according to a group of Italian astronomers, the Earth will be spared. The astronomers report that a nearby star called V 391 Pegasi has a planet orbiting it at about the same distance as we are to our sun. Remarkably, this planet has survived V 391 Pegasi's transformation to a red giant, so there's hope for Earth. Unfortunately, even though the Earth will survive, we will not. When the sun becomes a red giant, the intense heat and proximity of the sun will scorch the Earth and boil off the oceans. Perhaps within five-billion years, humans will have evolved into higher, purely spiritual beings, and we'll have no need for a planet anyway. link

Japanese head for the moon

Given all we know about distant planets and their moons, it is surprising that we still haven't got a definitive theory about where the moon came from. This morning, the Japan Aerospace Exploration Agency (JAXA) launched their Selenological and Engineering Explorer (SELENE) satellite. The satellite will orbit the earth a couple of times, and then head for the moon. After reaching the moon's orbit, it will launch two support satellites, and over the next year the satellite system will send back lunar topography and gravity data in unrivalled detail . This data is expected to firm up the 'giant impact' theory. According to this theory, a planetary body slammed into Earth 4.5-billion years ago, and the resulting debris eventually gathered to form the moon. link

The healing power of embryonic stem cells

Embryonic stem cells are formed so early in an organism's development that they have an almost magical ability to grow into any kind of cell and perform any function. For some time now, researchers have sought ways to recruit these adaptable cells to replace others that have been damaged by diseases like cancer and Alzheimer's. But recently, it was seen that embryonic stem don't just replace damaged cells, they also release chemical signals that prompt the defective cells to reboot and start developing properly. After examining tissue that was repaired by the injection of embryonic stem cells, it was determined that only one in five of the repaired cells were actually descendants of the injected embryonic stem cells. The rest repaired themselves after receiving signals from the injected stem cells. link

Neanderthals not the victim of climate change

What happened to the Neanderthals? They lived in Europe until about 30,000 years ago. After comparing the most likely dates of their extinction to climate data, scientists have concluded that their extinction was not caused by climate change. Their extinction was most likely due to their inability to complete with a more intelligent species: humans. link

Wow is an understatement

A year and a half ago, I stopped blogging. It seemed like I was shouting into an anthill, and I lost interest. I looked at my blog today. I haven't looked at it for a long time. I actually had comments, and I missed them while I was on hiatus. Thank you, much too late, for your comments. I'm back.