New evidence from climate records of the past provides some of the strongest indications yet of a direct link between tropical warmth and higher greenhouse gas levels, say scientists at the University of California, Santa Barbara. The present steady rise in tropical temperatures due to global warming will have a major impact on global climate and could intensify destructive hurricanes like Katrina and Rita.

The link between increased atmospheric greenhouse gas and global temperatures underlies the theory of global warming, explained Martin Medina Elizalde and David Lea. This link can be established by computer climate models or modern observations. Another way to study the link is through paleoclimate observations where past climate is reconstructed through natural archives. This latest study is based on such paleoclimate observations; the scientists analyzed the chemical composition of fossil plankton shells from a deep sea core in the equatorial Pacific.

"The relationship between tropical climate and greenhouse gases is particularly critical because tropical regions receive the highest proportion of solar output and act as a heat engine for the rest of the earth," said Lea.

Modern observations of tropical sea surface temperature indicate a rise of one to two degrees Fahrenheit over the last 50 years, a trend consistent with rising carbon dioxide in the atmosphere due to fossil fuel combustion, according to the authors. The paleoclimate evidence from this new study supports the attribution of the tropical temperature trend to the ever-increasing greenhouse gas burden in the atmosphere.

The research demonstrates that over the last 1.3 million years, sea surface temperatures in the heart of the western tropical Pacific were controlled by the waxing and waning of the atmospheric greenhouse effect. The largest climate mode shift over this time interval, occurring ~950,000 years before the present (the mid-Pleistocene transition), has previously been attributed to changes in the pattern and frequency of ice sheets.

The new research suggests instead that this shift is due to a change in the oscillation frequency of atmospheric carbon dioxide abundances, a hypothesis that can be directly tested by deep drilling on the Antarctic Ice Cap. If proved correct, this theory would suggest that relatively small, naturally occurring fluctuations in greenhouse gases are the master variable that has driven global climate change on time scales of ten thousand to one million years." >from *Link between tropical warming and greenhouse gases stronger than ever, say scientists*. October 13, 2005

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> climate change: message from the artic indigenous peoples. december 21, 2004
> earth 'will expire by 2050': living planet report. july 12, 2002

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> tropical heat engine

sonic flow
> foraminifera's chemical compositions [stream]
foraminifera's chemical compositions [download]

Researchers at the University of Pennsylvania School of Medicine have demonstrated that star-shaped glial cells in the brain called astrocytes are directly involved in regulating communication between neurons. A central finding of the study is that astrocytes modulate the level of a signaling molecule called adenosine, which is thought to be important in controlling wake-to-sleep transitions and epileptic seizures.

“This finding may cause neuroscientists to radically alter their view of the role of astrocytes as merely supportive to one of actively communicating with and instructing neurons,” states senior author Philip G. Haydon, PhD, Professor of Neuroscience. “Astrocytes are not just the ‘kitchen cells’ of the brain, providing nutritional support, but instead also help the neurons talk to each other.”

The central nervous system, which includes the brain and spinal cord, is composed of specialized cells called neurons that send out and receive chemical signals called neurotransmitters across a space called the synapse. This process results in transmission of a nerve impulse. Historically, the glial cell or astrocyte was considered to be a support cell and to play no active role in regulating nerve impulse transmission. However, recent research by Haydon and other investigators has indicated that glial cells do produce chemical transmitters called gliotransmitters and that these chemical signals are recognized by the neurons. The studies that have shown capability were conducted on isolated nerve cells or on slices of brain tissue.

In this most recent study, the researchers made genetic manipulations to glial cells in live mice, thus directly demonstrating how astrocytes function in the brain. The mice were engineered to produce a protein called SNARE in their astrocytes. When the SNARE protein was produced, the amount of adenosine decreased.

When adenosine accumulated, nerve impulses were suppressed and could not be transmitted across the synapse. This helps explain why high adenosine levels can suppress epileptic seizures.

In contrast, low levels of adenosine increased the transmission of nerve impulses. The modulation of neuronal activity through the regulation of the level of adenosine in the synapse may explain the nature of wake-to-sleep transitions during periods of drowsiness.

“The next step is to study the behavior of these mice during manipulation of adenosine levels in the brain,” says Haydon. >from *Penn Study Finds Direct Role for Glial Cells in Brain Cross-talk* . Findings may help elucidate mechanisms of wake-sleep transitions and epileptic seizures. October 11, 2005

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> signaling us wake-to-sleep transitions

sonic flow
> glial [stream]
glial [download]

Place Lab is software providing low-cost, easy-to-use user positioning for location-enhanced computing applications. Unlike existing positioning systems, Place Lab tries to provide positioning which works worldwide, both indoors and out, and is privacy observant. Place Lab clients can determine their location privately without constant interaction with a central service.

The Place Lab approach is to allow commodity hardware clients like notebooks, PDAs and cell phones to locate themselves by listening for radio beacons such as 802.11 access points, GSM cell phone towers, and fixed Bluetooth devices that already exist in the environment. These beacons all have unique or semi-unique IDs, for example, a MAC address. Clients compute their own location by hearing one or more IDs, looking up the associated beacons' positions in a locally cached map, and estimating their own position referenced to the beacons' positions.

This whitepaper introduces an open source toolkit that lets mobile devices determine their locations with the aid of freely accessible, nearby radio sources, such as fixed Bluetooth devices, 802.11 access points, and GSM cell towers. Basically, the device reads the IDs of these local "radio beacons" (each of which has a unique or semi-unique ID), looks up their positions in a locally-cached database, and performs a computation akin to triangulation. According to the whitepaper, over four million of the required radio beacons have already been mapped.

Location awareness is an important capability for mobile computing. Yet inexpensive, pervasive positioning—a requirement for wide-scale adoption of location-aware computing—has been elusive. We demonstrate a radio beacon-based approach to location, called Place Lab, that can overcome the lack of ubiquity and high-cost found in existing location sensing approaches. Using Place Lab, commodity laptops, PDAs and cell phones estimate their position by listening for the cell IDs of fixed radio beacons, such as wireless access points, and referencing the beacons’ positions in a cached database.

Our coverage experiment confirmed the intuition that GPS, often thought of as a pervasive location technology, in fact lacks availability in people’s daily lives since people are frequently indoors or under cover, whereas 802.11 and GSM beacons are frequently available both indoors and out. This experiment was conducted by logging beacon availability using small recorders carried by people as they went about their daily routines.

Binary and source releases of Place Lab are available for many platforms along with sample radio traces at http://www.placelab.org/. >from *Place Lab: Device Positioning Using Radio Beacons in the Wild*

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> blur building: inhabitable cloud. using tracking and location technologies. march 4, 2002
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imago
> the radio beacon emotional toolkit

sonic flow
> computing location [stream]
computing location [download]

Power plants of the future may be designed to provide electricity solely for an individual housing estate, village, factory or college. That's the prediction of University of Southampton engineer Dr Tom Markvart.

He claims large-scale systems of electricity generation used at present waste considerable amounts of energy by producing unwanted heat. It is also difficult to incorporate environmentally-friendly sources of energy such as wind farms and solar panels because of their intermittent and unpredictable outputs.

Dr Markvart, of the University's School of Engineering Sciences (SES), is advocating the development of microgrids to provide a stable and reliable power supply from various energy sources. Small-scale generating equipment sited close to the eventual energy users could act as a stand-alone source of power, especially in remote areas, or be linked to the national grid. Energy storage devices would provide extra power at times of high demand. The proximity to customers would help boost energy efficiency to around 80 per cent compared to 35-40 per cent for a conventional generation system.

'In the long term, microgrids offer the promise of substantial energy savings and reduction in emissions, without a major change in our lifestyle,' said Dr Markvart.

Initiatives to test small-scale energy generation are already underway. They include the former Mont-Cenis coal mine in Germany, where a microgrid powers an academy, hospital and nearby housing. Ecologically-friendly ways of energy production include the Southampton Geothermal Project, which uses hot water from deep beneath the city.

Dr Markvart's research appears in the latest edition of the Royal Academy of Engineering's Ingenia magazine. The research was carried out in collaboration with, amongst others, Dr Suleiman Abu-Sharkh (SES) and Dr Neil Ross (School of Electronics and Computer Science), both also at the University of Southampton. >from *Small is beautiful - Southampton scientist proposes new efficient and eco-friendly power plants* . September 23, 2005

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> microgrids power

sonic flow
> small power plants [stream]
small power plants [download]