The climatic changes on Earth are mostly driven by the oceanic currents. These currents tend to confine themselves to either sides of the Equator. When waters from North and South meet at the Equator, they combine lazily and create an utter lack of wind known as the doldrums.
However, a new study (published in the journal Science) finds certain connections between the climates in the two hemispheres in the long run. According to researchers from Universitat Autonoma de Barcelona in Spain and the Cardiff University in the UK, ocean circulations in the Southern hemisphere have adapted to sudden changes in the North.

Great Ocean Conveyor Belt (Courtesy: NASA)Interestingly enough, the researchers found that several times in history, an increase in the temperature in the Northern hemisphere precipitated a cooling period in the South. Conversely, a cooler Northern hemisphere resulted in a warmer Southern hemisphere! Computer models have predicted this behavior, but this is the first time this has been discovered in the weather records.
The cause seems to be linked to how the oceanic streams transport heat from one part of the ocean to another. For example, the climate of the Northern Atlantics is greatly influenced by the warm waters carried by the Gulf stream (from the Gulf of Mexico). But the strength of this stream depends on the salinity of the southbound water; if salinity decreases, the current weakens.
From time to time, a melting of the Greenland ice-sheets would introduce fresh water into the Northern Atlantic, thus reducing the salinity of the Northern ocean. This in turn would weaken the gulf-stream, thus slowing the heat transport from the Southern hemisphere. Therefore, as the North cools, the South warms up.
Conversely, when a warmer and more saline North (due to more evaporation of sea-water) keeps the gulf stream strong, it results in more heat transfer from the South (and thereby cooling it). As the North heats up, the melting of Greenland ice slowly cools the North, and the cycle starts all over again.

Today's post is not about any new innovation/advancement, but a sad statement on the way science is being short-changed in the United States. The Hubble telescope has been the diamond in the crown of modern space explorations. Launched in 1990 by the space shuttle Discovery, Hubble has performed with near precision (notwithstanding some major and minor repairs) for nearly 15 years now. Hubble could still go on for several years (with some repairs), but soon this crowning achievement will be fitted with rockets, which will bring it crashing down into the Pacific Ocean.

Hubble Space Telescope (Courtesy: NASA)A major review last week of servicing the Hubble Space Telescope has led NASA officials to a deorbit only position. Backed (perhaps unsurprisingly) by the White House, the tele-robotic mission (that would have used a robot/robotic arm to fix the gyroscopes and do some other maintenance) has been scrapped. After the Columbia disaster, a manned mission was scrapped as well, supposedly on safety grounds, despite the astronauts' statements that are perfectly willing to take the risk.
So how healthy is Hubble now? As I mentioned in one of my previous posts, Hubble currently has three working gyroscopes, and scientists have managed to make it work even on two, which might allow Hubble function until 2008. The batteries might fail by 2010. So, we can expect another (at the most) 2-3 good years from Hubble. So start writing your obituaries now :(:(.
On a lighter note, this is my 60th post (Diamond Jubilee!). Somehow, writing about this diamond in the sky seemed strangely appropriate.

US researchers from Stanford University have developed a bionic eye, which has been successfully tested in rats. According to the research team, the eye implant - a 3-millimetre-wide chip that would fit behind the retina - could be a dramatic step above currently available technology.

Bionic Eye System (Courtesy: Stanford University)Published in the Journal of Neural Engineering, the system is a retinal prosthesis system that can stimulate the retina with resolution corresponding to a visual acuity of 20/80—sharp enough to orient yourself toward objects, recognize faces, read large fonts, watch TV and, perhaps most important, lead an independent life. The researchers tested the system in rats, but human trials are at least 3 years away.
Degenerative retinal diseases (such as age-related macular degeneration) is caused in 700,000 people each year in the USA alone. In such a disease, the rod-shaped photoreceptors at the retina's periphery (responsible for night vision), and cone-shaped cells (color vision) are damaged. However, the retina is still intact, and if it could be directly stimulated, some functionalities could be restored.
The complete setup includes a small chip implanted directly onto the eye, a wearable computer, a video camera, and a pair of infra-red goggles. First, light from (say) a flower enters the video camera. The video camera then sends the image of the flower to the wallet-sized computer for complex processing. The processor then wirelessly sends its image of the flower to an infrared LED-LCD screen mounted on the goggles. The transparent goggles reflect an infrared image into the eye and onto the retinal chip. The chip converts the image to the visual range, and projects it onto the retina.
This design employs a pixel density of up to 2,500 pixels per millimeter, corresponding to a visual acuity of 20/80, which could provide functional vision for reading books and using the computer. This is significantly better than the currently existing technologies, which provide only a few pixels per millimeter. The work is a synergy of diverse fields: biology, electronics, physics, and signal processing.

Gravitropism is the movement of a plant based on the strength and direction of gravity. For example, when a seed sprouts, the roots always grow down into the soil, whereas the stem grows upward. A germinating seed can be turned upside down several times and the root will still start to bend downwards. A team of biologists from the University of California, Riverside has used chemical genomics to identify novel compounds that affect this ability of plants to alter their direction of growth in response to gravity.

Tonoplast aggregrates (Courtesy: University of California, Riverside)The team published its findings in the Proceedings of the National Academy of Sciences. The researchers analysed some 10,000 small molecules to identify those that could positively or negatively affect gravity’s effect on plant growth, which is closely linked to the movement of proteins through plant cell membranes.
The work focusses on using these molecules to disrupt, or reorient the growth of the plant in any particular direction. This is easier to do than other approaches, which use genetic mutations to alter the plant behavior. The team narrowed their search down to 4 chemicals, which affected gravitropism and the movement of proteins through membranes within the plant cell. The chemicals affect the growth of tonoplasts (membrane surrounding the vacuole), and this indirectly regulates the direction in which a plant will grow.
This research was supported by NASA, and will have applications such as growing plants in space. If successful, this would allow astronauts to grow their own food, and also regenerate the oxygen during long space missions.

Anyone who has used a battery-powered device knows how annoying it is to sit and wait for it to recharge. Now Toshiba has come up with a novel Lithium-Ion battery that recharges 80% of a battery's energy capacity in only one minute. This is about 60 times faster than the typical Lithium-Ion battery in use today :).

The new battery employs latest advances in nano-material technology, which allows the negative electrode to use new nano-particles to prevent organic liquid electrolytes from reducing during battery recharging. The nano-particles quickly absorb and store vast amount of lithium ions, without causing any deterioration in the electrode.
The battery also has a long life-cycle (loses only 1% of capacity after 1,000 cycles of discharging and recharging), and can operate at very low temperatures (-40° C). Other advantages include: very small and light (3.8mm thick, 62mm high and 35mm deep), and eco-friendly (less energy wasted in recharging). The battery also has a very high energy density of 600mAh (Milli-Ampere Hour).
Toshiba will bring this battery into commercial production by 2006. The first users would be in the automotive and industrial sectors, where the slim, small-sized battery will deliver large amounts of energy while requiring only a minute to recharge. The size, weight and safety will make it ideal for hybrid vehicles.
There is no info about when it will be ready for laptops, so keep carrying all those heavy laptops for now :).

Scientists normally estimate the age of a rocky planet like Mars by counting the number, size and distribution pattern of craters on its surface. The idea: the older a surface, the more craters should have accumulated over time. Crater counts thus give an indication of the relative age of different Martian regions. Scientists would then compare the crater counts with similar regions on the moon, which have already been exactly dated by using the rocks from the moon, and thus arrive at an exact date for the martian regions.
However, it looks like this method of computing the age of different Martian regions is flawed.

A typical Martian crater (Courtesy: NASA)According to Nadine Barlow of Northern Arizona University in Flagstaff, USA, pictures from NASA's Mars Explorer spacecraft detected faint ray-like lines emanating from even the smallest of craters. This suggests that a lot of debris went up in the air when the meteorite hit the surface, and that falling debris must have caused a lot of secondary craters in the region. This would mean that the way crater-counting is done is flawed, since the current methods would have counted the secondary craters as craters from meteorite impacts. This would skew the result, and the region would seem to be much older than it actually is.
The findings will significantly change our estimations on when different regions of Mars were volcanically active. The vast majority of craters smaller than 2 kilometres in diameter may be secondary craters, making them virtually useless for dating surfaces. Therefore, all estimations that are based on craters, have to be revisited. This will have implications for our understanding of the evolution of Mars, when water last existed on Mars, and consequently, our understanding of why it disappeared and when life might have formed there or gone extinct.

Carbon nanotubes are cylindrical chains composed purely of carbon atoms. Due to their unique structure, they exhibit unusual strength and unique electrical properties, and are efficient conductors of heat. The tubes have huge potential in the fields of nanotechnology, electronics and superconductivity, among others.
Now scientists at Sandia National Laboratories have demonstrated that organic nanotubes, married to an inorganic catalyst, can harness sunlight to turn water into pure hydrogen and oxygen.

Water molecules confined in a nanotube (Courtesy: AIP)Such organic nanotubes are already in use in nature. For example, our blood uses porphyrin nanotubes, which provide the power by which hemoglobin forms new proteins. The Sandia researchers believe they can harness the same mechanism to power automobiles with water. In fact, their laboratory created tube mimics one naturally occuring tube called the chlorosome, which is found in some photosynthetic bacteria! One day, fuel cells composed of such nano-structures might be able to reduce our dependence on fossil fuels.
The researchers were able to synthetically create the nanotubes in an aqueous solution. The tube has two different regions for generating hydrogen and oxygen respectively, in the presence of sunlight. The two gases are emitted from the two sides of the tube, where they can be captured and stored separately.
The next step is to create an array of these tubes, so that it can act as a solar cell that will generate hydrogen and oxygen. The porphyrin nanotubes are similar in size to carbon nanotubes, measuring up to 1 micron long but only 50 to 70 nanometers in diameter, with walls just 20 nm thick. They self-assemble easily (in an aqueous solution, for example) and it is quite conceivable to easily and cheaply produce them en masse.
Further usages of such a device could be in the fields of electronics, photonics, and chemical sensors.