The world of computing is in transition. As chips become smaller and faster, they dissipate more heat, which is energy that is entirely wasted.
By some estimates the difference between the amount of energy required to carry out a computation and the amount that today's computers actually use, is some eight orders of magnitude. Clearly, there is room for improvement.
So the search is on to find more efficient forms of computation, and there is no shortage of options.
One of the outside runners in the race to take the world of logic by storm is reversible computing. By that, computer scientists mean computation that takes place in steps that are time reversible.
So if a logic gate changes an input X into a output Y, then there is an inverse operation which reverses this step. Crucially, these must be one-to one mappings, meaning that a given input produces a single unique output.
These requirements for reversibility place tight constraints on the types of physical systems that can do this kind of work, not to mention on their design and manufacture. Ordinary computer chips do not qualify--their logic gates are not reversible and they also suffer from another problem.
When conventional logic gates produce several outputs, some of these are not used and the energy required to generate them is simply lost. These are known as garbage states. "Minimization of the garbage outputs is one of the major goals in reversible logic design and synthesis," say Himanshu Thapliyal and Nagarajan Ranganathan at the University of South Florida.
Today, they propose a new way of detecting errors in computations and say that their method is ideally applicable to reversible computing and, what's more, naturally reduces the number of garbage states that a computation produces.
Before we look at their approach, let's quickly go over a conventional method of error detection. This simply involves doing the calculation twice and comparing the results. If they are the same, then the computation is considered error free.
This method has an obvious limitation if the original computation and its duplication both make the same error.
Thapliyal and Ranganathan have a different approach which gets around this problem. If a reversible computation produces a series of outputs, then the inverse computation on these outputs should reproduce the original states.
So their idea is to perform the inverse computation on the output states and if this reproduces the original states, then the computation is error free. And because this relies on reversible logic steps, it naturally minimises the amount of garbage states that are produced in between.
There are one or two caveats, of course. The first is that nobody has succeeded in building a properly reversible logic gate so this work is entirely theoretical.
But there are a number of computing schemes that have the potential to work like this. Thapliyal and Ranganathan point in particular to the emerging technology of quantum cellular automata and show how their approach might be applied.
The beauty of this approach is that it has the potential to be dissipation-free. So not only would it use far less energy than conventional computing, it needn't lose any energy at all. At least in theory.
At first glance, that seems to contradict one of the foundations of computer science: Rolf Landauer's principle that the erasure of a bit of information always dissipates a small amount of energy as heat. This is the basic reason that conventional chips get so hot.
But this principle need not apply to reversible computing because if no bits are erased, no energy is dissipated. In fact, there is no known limit to the efficiency of reversible computing. If a perfectly reversible physical process can be found to carry and process the bits, then computing could become dissipation free.
For the moment, that's wild dream. But in the next few years, as quantum processes begin to play a larger part in computation of all kinds, we may well hear much more about reversible computing and its potential to slash the energy wasted in computing.
Australian designer Jaron Dickson has come up with a concept for a hydrogen-powered, flying yacht. If that wasn’t cool enough, the yacht is based on the legendary Soviet super-vehicle the Ekranoplan. As a result, this cool little boat, which has been shortlisted for an Australian Design Award, is called the EkranoYacht – read on for a look!
For those of you not familiar with the Ekranoplan, it was a massive vehicle conceived in Scandinavia but realized by the Soviets during the Cold War. Essentially half plane, half boat, the Ekranoplan would ‘skim’ across the water (or land) on short wings using the ‘ground effect’. This allowed the vehicle to ‘fly’ just above the ground on of a cushion of high-pressure air created by the aerodynamic interaction between the wings and the surface. The Soviets design a massive 550-ton Ekranoplan that could transport vehicles and troops at an a stunning 450mph – all while remaining up to 66 feet over the water. Unsurprisingly, it earned the nickname “The Caspian Sea Monster”. Unfortunately, their production fell with the collapse of the Soviet Union.
Ok, science and history lesson over! Back to the EkranoYacht!
According to Dickson, who is a student at Monash University in Australia, the EkranoYacht is a “hydrogen powered wing-in-ground effect vehicle for permanent residence – set for 2025. The conventional ways of living have changed dramatically, people are less bound by the country or topographical location which they reside. Using hydrogen power and flying 4m above the water’s surface, the project focuses on more efficient sea travel and protecting the environment. To truly show your wealth and success is freedom, and the ultimate freedom is bringing you home where ever you go.”
Dickson added that, “Humans are always thinking of new ways travel and improve their dynamic lives. My design is a ‘blue-sky concept’, but this type of forward and different thinking could possibly turn into a reality one day. My project has the livability of a yacht and the convenience of an aeroplane.”
CAS technology could mean organ transplants of the future won't be the frantic race against time they are now. It has been possible to successfully cryopreserve semen, blood, embryos, oocytes, stem cells and other thin samples of small clumps of cells for a few decades now. However, cryopreservation of human internal organs, such as livers and hearts for storage and transplant, currently requires toxic doses of cryoprotectants – substances that protect biological tissue from freezing damage due to ice formation – in order to survive the cooling process. A solution could be at hand in the form of a technology used to preserve sushi that can instantly freeze water, meaning there is no time for cell damaging ice crystals to form. In fact, it’s already being used to preserve teeth.
The common misconception is that the freezing of organs will cause the cells to burst due to the formation of ice crystals within the cell, but this only occurs if the freezing rate exceeds the osmotic loss of water to the extracellular space. This makes it possible to freeze small biological samples in a process known as slow programmable freezing (SPF) or controlled-rate and slow freezing. This is currently for oocyte, skin, blood products, embryo, sperm, stem cells and general tissue preservation in hospitals, veterinary practices and research labs around the world.
However, freezing larger organs or even whole human beings can cause serious damage as a result of ice forming between cells, causing mechanical and chemical damage. To prevent this, larger doses of toxic cryprotectants are used to remove and replace water inside cells with chemicals that prevent freezing. While this can reduce the damage from freezing, the toxicity can still cause serious injuries that aren’t reversible with present technology – meaning we’re not likely to see James Bedford – the first person whose body was frozen and remains cryopreserved – up and about any time soon.
A newer technique known as vitrification, which involves an extremely rapid drop in temperature, claims to provide the benefits of crypreservation without damage due to ice crystal formation. But again, damaging levels of cryoprotectants are needed. This time to increase the viscosity and lower the freezing temperature inside the cell.
Freezing without cryoprotectants
Now a research group at Hiroshima University, borrowing supercooling technology used to preserve sushi and high-end food delicacies, has proven it is possible to freeze cells without the use of toxic cryprotectants. As reported on Singularity Hub, the “Cells Alive System” (CAS) produced by Japanese company ABI prevents freezing at supercool temperatures by vibrating the water using magnetic fields. This allows the water to be supercooled so that when the magnetic field is turned off, the water freezes instantaneously – too fast for damaging ice crystals to form.
The patented CAS technology is already being used at the world’s first commercial tooth bank, The Teeth Bank, to preserve teeth and potentially as an alternative source for harvesting stem cells. The Teeth Bank allows removed teeth, previously disposed of as worthless medical waste, to be stored and re-implanted when needed. Preserved teeth can even be sculpted into different teeth before re-implantation.
The CAS technology has even been proven to reserve the tooth ligaments – an important factor for re-implantation. A 2010 study published in the journal Cryobiology detailed how the ligaments of a fresh tooth slow frozen without the CAS technology were severely damaged, while the ligaments of another tooth frozen using the CAS technology survived showing only minor damage and grew as well as those from a fresh tooth.
The technology could obviously have potential for the preservation of internal organs that currently have only a brief window of viability after being removed from a donor. Thanks to burgeoning technology, it could also provide a way for people to store replacement organs grown from their own stem cells instead of waiting on a compatible donor.
Socio-economic disparities in diet patterns and nutrient intake are well documented in research. People with lower incomes and less education typically have less healthful eating habits than people with higher incomes and more education. But little is known about the extent to which those disparities are driven by higher monetary costs of nutritious foods.
Now, a new study from University of Washington researchers concludes, for the first time, that socio-economic disparities in diet quality are directly affected by diet costs. The study, "Are socio-economic disparities in diet quality explained by diet costs?" is published in advance online in the Journal of Epidemiology & Community Health.
UW researchers have previously found that better quality diets are more costly than less nutritious diets, and that there is a rising disparity in the price of healthful foods. "The twist with this new study is that we've connected the dots that could explain why people in a lower socio- economic status have less nutritious diets," said Pablo Monsivais, UW acting assistant professor of epidemiology.
Monsivais, with Program Manager Anju Aggarwal and UW Professor Adam Drewnowski, studied data of more than 1,300 men and women from the Seattle Obesity Study, a population-based study of food access, diet quality and health among King County, Wash. residents.
The researchers first looked at how diet cost was associated with educational attainment and household income, two indicators of socio-economic position. They used statistical methods to control for total calorie intake and other factors. The average diet cost was higher for people with higher educational attainment and higher household income. People with lower educational attainment had diet costs that were an average of $1.09 per day lower than that of persons in the highest group ($8.19 to $9.28 per day).
People with the highest educational attainment or income also enjoyed the most nutritious diets. Those in the highest income group reported diets that were on average 9.3 points higher in nutrient density than diets reported by the lowest income group (96.6 versus 87.3 percent), after controlling for dietary and demographic factors. However, after taking the cost of food into account, the difference in dietary nutrient density between the highest and lowest groups shrank to 1.4 percentage points (93.0 versus 91.6 percent). "These results tell us that cost is a major factor in explaining the differences in eating habits between people of lower and higher socioeconomic level" said Monsivais.
Monsivais said the Seattle study should be replicated on a wider, more diverse (in terms of education, income) section of Americans--or in another country. "What is the average person's concept of nutritious food, too?" Monsivais said. "We don't know that, and it might explain some amount of the variation we found."
The Centers for Disease Control and Prevention's NHANES (National Health and Nutrition Examination Survey) could also be tapped to further explore the socio-economic question, he said.
Study results provide fodder for new and different nutrition policy and interventions, which for the last several decades have been mostly premised on the idea that poor diets were due to a lack of nutrition knowledge or insufficient motivation for healthy eating. "The most universal policy change or intervention would be to rethink how we encourage the production of foods," said the researcher. "In this country, we have a very expensive agricultural subsidy program that targets a limited range of foods that are not part of a nutritious diet. We do not support fresh produce or seafood, but instead support the production of inexpensive sugars, fat and refined grains. We need to align public health priorities with agricultural policies because it affects the largest number of people."
In addition, Monsivais said states could be more creative with public school food programs and other nutrition efforts that impact low-income people. California has experimented with an electronic benefits transfer program (food stamps) that rewards people who buy fresh produce, which makes having a healthier diet easier and more affordable.
Food retailers and grocers could also help consumers make healthier choices, said Monsivais. When you swipe a "member" card at a local store, it could be used in a helpful and healthful way, offering up coupons for items that are nutrient-rich. "If we could overlay a health lens on top of the member cards and make recommendations that are aligned with the way consumers eat and incentives, we could make it interesting for people."
Scientists said Monday they were moving closer to coming up with a non-physical definition of the kilo after discovering the metal artefact used as the international standard had shed a little weight.
Researchers caution there is still some way to go before their mission is complete, but if successful it would lead to the end of the useful life of the last manufactured object on which fundamental units of measure depend.
At the moment, the international standard for the kilo -- the equivalent of around 2.2 pounds -- is a chunk of metal, under triple lock-and-key in France since 1889.
But Scientists became concerned about the cylinder of platinum and iridium housed at the International Bureau of Weights and Measures (BIPM) in Sevres, near Paris, after discovering it had mysteriously lost a tiny amount of weight.
Experts at the institute revealed in 2007 that the metal chunk is 50 micrograms -- 0.0000017 ounces -- lighter than the average of several dozen copies, meaning it had lost the equivalent of a small grain of sand.
They are now searching for a non-physical way of defining the kilo, which would bring it in line with the six other base units that make up the International System of Units (SI).
The other units are the metre, the second, the ampere, the kelvin, the mole and the candela, and none of them are now based on a physical reference object.
Experiments are focused on establishing a link between mass and the Planck constant, the fundamental unit of measurement in quantum physics, to provide a new definition of the kilo.
Michael Stock, a BIPM scientist who will on Monday discuss the proposed change in London, said the metal chunk, known as the "international prototype", was coming to the end of its useful life.
"Measurements get more and more precise, and precise measurements require well-defined measurement units to express their results," he said.
He added that "our experiments are moving forward, however, it is too early to implement the new definition of the kilogram just yet."
Scientists recently discovered that DNA can be used as a molecular scaffold to make metal contacts to organic semiconductors. A key step in this process involves being able to tether the DNA to various surfaces and stretch the molecule to varying lengths.
Zhenan Bao and colleagues' new strategy involves synthesizing hybrid DNA-organic molecule-DNA (DOD) structures, then stretching and tethering the DOD assemblies between two microscopic metal electrodes. The researchers then make metal electrode-organic molecule-metal electrode (MOM) structures by further metallizing the DNA segments within the DOD structures.
The team then exploited so-called biotin-Streptavidin linkage chemistry to tether the DNA assemblies to device surfaces (quartz in this case). The basic steps are as follows: functionalizing the surface with amine (-NH2) terminated silanes; reacting the amines with N-hydroxysuccinimide (NHS) functionaliszed polyethylene glycol (PEG) chains terminated with biotin; and using Streptavidin to create a link to biotin-terminated DNA molecules.
A crucial step
"We have made progress in synthesizing these DOD hybrid structures and have now developed a reproducible surface chemistry technique to tether DNA molecules of different lengths to substrate surfaces," team member Guihua Yu told nanotechweb.org. "We have also developed a shear flow processing method to control DNA stretching and alignment. This represents a crucial step in making large-scale nanoelectronic devices based on DOD array structures."
Aside these practical applications, the technique could also be used to study single DNA molecules and how they rotate. DNA tethering and stretching may also help in manipulating nucleotides in single DNA molecules for genetic applications and to study how DNA reacts with proteins at the single-molecule level, said Yu. Other single-molecule technologies, such as DNA sequencing could also benefit.
Spurred on by these first results, the team is now working on a controllable, double-tethering process while developing in situDNA metallization for ultimately making larger-scale nanoelectronic devices based on single organic molecules. "We will then perform electrical transport measurements on these device arrays to probe how charge travels through single molecules with different chemical functionalities and length," added Yu.
Israeli researchers have created a recyclable membrane based on supramolecular linkages that can be used to filter nanoparticles. The membrane, which unusually comprises non-covalent bonds, performs just as well as conventional sieves, offering a green and versatile alternative for size-separation and purification of nanoparticles.
Standard filtration membranes are usually held together by strong covalent bonds, which give membranes suitable strength to withstand the pressures involved in filtration processes. The problem is that when membranes become clogged up they have to be discarded and replaced.
One idea is to make membranes based on supramolecular (non-covalent) interactions which can undergo reversible self-assembly. Since the bonds can be undone easily, they offer a recyclable and adaptable option. But making such membranes with a level of robustness to rival conventional options has remained a challenge.
Now, Boris Rybtchinski and colleagues at the Weizmann Institute of Science in Rehovot, Israel, have managed to make a robust and recyclable untrafiltration membrane with non-covalent hydrophobic linkages. 'This results in easy fabrication, recyclability, and versatility that cannot be achieved with regular covalent materials,' says Rybtchinski.
The team created a compound that self-assembles in water. It has a specially designed large and flat hydrophobic surface. 'In water, these surfaces experience very large attractive forces that hold them together, eventually forming porous nanostructured 3D networks possessing high robustness,' Rybtchinski explains. By filtering these structures onto a cheap commercial support with 400nm pores, they form a nanostructured membrane that works as a nanoparticle sieve.
The hydrophobic interactions are strong enough to hold together the membrane and withstand the flow of particles, says Rybtchinski. Experiments with solutions containing gold nanoparticles of various sizes revealed that only particles smaller than 5nm could pass through a 12µm thick membrane. By increasing the thickness to 45µm, the team discovered that the membrane could separate smaller particles (CdTe quantum dots of 2-4nm in size) because of a time delay between different sized particles passing through the membrane, resulting in size-selective chromatography.
The membrane is easily disassembled by adding solvents such as ethanol which weakens the hydrophobic interactions. 'This way the material can be retrieved, cleaned, and reused for fabrication of another membrane,' says Rybtchinski. Furthermore, particles that are stuck in the filter can be recycled too, which is not always possible with conventional membranes.
Jonathan Nitschke, who researches self-assembling polymers at the University of Cambridge, UK says that Rybtchinski's use of non-covalent interactions to knit together a filtration membrane is innovative. 'Supramolecular linkages can be undone under certain conditions, allowing the membranes to be dissolved and recreated so it's an excellent way of cleaning and recycling them.'
Space launches have evoked the same image for decades: bright orange flames exploding beneath a rocket as it lifts, hovers and takes off into the sky. But an alternative propulsion system proposed by some researchers could change that vision.
Instead of explosive chemical reactions on-board a rocket, the new concept, called beamed thermal propulsion, involves propelling a rocket by shining laser light or microwaves at it from the ground. The technology would make possible a reusable single-stage rocket that has two to five times more payload space than conventional rockets, which would cut the cost of sending payloads into low-Earth orbit.
NASA is now conducting a study to examine the possibility of using beamed energy propulsion for space launches. The study is expected to conclude by March 2011.
In a traditional chemical rocket propulsion system, fuel and oxidizer are pumped into the combustion chamber under high pressure and burnt, which creates exhaust gases that are ejected down from a nozzle at high velocity, thrusting the rocket upwards.
A beamed thermal propulsion system would involve focusing microwave or laser beams on a heat exchanger aboard the rocket. The heat exchanger would transfer the radiation's energy to the liquid propellant, most likely hydrogen, converting it into a hot gas that is pushed out of the nozzle.
“The basic idea is to build rockets that leave their energy source on the ground,” says Jordin Kare, president of Kare Technical Consulting, who developed the laser thermal launch system concept in 1991. “You transmit the energy from the ground to the vehicle.”
With the beam shining on the vehicle continually, it would take 8 to 10 minutes for a laser to put a craft into orbit, while microwaves would do the trick in 3 to 4 minutes. The vehicle would have to be designed without shiny surfaces that could reflect dangerous beams, and aircraft and satellites would have to be kept out of the beam’s path. Any launch system would be built in high-altitude desert areas, so danger to wildlife shouldn’t be a concern, Kare says.
Thermal propulsion vehicles would be safer than chemical rockets since they can’t explode and don’t drop off pieces as they fly. They are also smaller and lighter because most of the complexity is on the ground, which makes them easier and cheaper to launch.
“People can launch small satellites for education, science experiments, engineering tests, etc. whenever they want, instead of having to wait for a chance to share a ride with a large satellite,” Kare says.
Another cost advantage comes from larger payload space. While conventional propulsion systems are limited by the amount of chemical energy in the propellant that's released by combustion, in beamed systems you can add more energy externally. That means a spacecraft can gain a certain momentum using less than half the amount of propellant of a conventional system, allowing more room for the payload.
“Usually in a conventional rocket you have to have three stages with a payload fraction of three percent overall,” says Kevin Parkin, leader of the Microwave Thermal Rocket project at the NASA Ames Research Center. “This propulsion system will be single stage with a payload fraction of five to fifteen percent.”
Having a higher payload space along with a reusable rocket could make beamed thermal propulsion a low-cost way to get material into low Earth orbit, Parkin says.
Parkin developed the idea of microwave thermal propulsion in 2001 and described a laboratory prototype in his 2006 PhD thesis. A practical real-world system should be possible to build now because microwave sources called gyrotrons have transformed in the last five decades, he says. One megawatt devices are now on the market for about a million US dollars.
"They're going up in power and down in cost by orders of magnitude over the last few decades,” he says. “We've reached a point where you can combine about a hundred and make a launch system."
Meanwhile, the biggest obstacle to using lasers to beam energy has been the misconception that it would require a very large, expensive laser, Kare says. But you could buy commercially available lasers that fit on a shipping container and build an array of a few hundred. "Each would have its own telescope and pointing system," he says. "The array would cover an area about the size of a golf course."
The smallest real laser launch system would have 25 to 100 megawatts of power while a microwave system would have 100 to 200 megawatts. Building such an array would be expensive, says Kare, although similar to or even less expensive than developing and testing a chemical rocket. The system would make most economic sense if it was used for at least a few hundred launches a year.
In addition, says Parkin, “the main components of the beam facility should last for well over ten thousand hours of operation, typical of this class of hardware, so the savings can more than repay the initial cost.”
In the near term, beamed energy propulsion would be useful for putting microsatellites into low Earth orbit, for altitude changes or for slowing down spacecraft as they descend to Earth. But the technology could in the future be used to send missions to the Moon or to other planets and for space tourism.
Kare has looked into the possibility of using lasers to propel interstellar probes for NASA’s Institute of Advanced Concepts. A deep space launch would require higher power lasers with larger telescope systems as well as laser relay stations in space. Powering missions over interplanetary distance would require even bigger lasers and telescopes, as well as different propulsion techniques using propellants easier to store than liquid hydrogen.
Sending a spacecraft to a moon of Jupiter, for instance, would require a laser that gives billions of watts of power. "You'd have to have another couple generations of space-based telescopes to do something like that,” Kare says. “You can in fact launch an interstellar probe that way but now you’re talking about lasers that might be hundreds of billions of Watts of power." Laser technology could reach those levels in another 50 years, he says.
Zeitgeist: Moving Forward, by director Peter Joseph, is a feature length documentary work which will present a case for a needed transition out of the current socioeconomic monetary paradigm which governs the entire world society.
This subject matter will transcend the issues of cultural relativism and traditional ideology and move to relate the core, empirical "life ground" attributes of human and social survival, extrapolating those immutable natural laws into a new sustainable social paradigm called a "Resource-Based Economy".
One voice can make a difference........a million voices can change the world!
Questions such as how much fresh water we have left on Earth, where it is located, and how we can access it are all nearly impossible to answer. However, scientists working on understanding and revealing the planet's surface structure are helping to hone in on an answer. University of British Columbia researchers have created a world's-first with their new map that outlines how fluid flows through Earth's various porous surfaces. Information gleaned from the map can help us discover more about water supplies worldwide.
According to Science Daily, the maps, published earlier this week in Geophysical Research Letters, could help with both water resource management and climate modeling, since a better understanding of how fluid permeates rock and sediments can reveal how and where rainwater travels as it flows into the water table. While most maps so far have dealt with permeability down to one or two meters of soil, and across smaller areas, this new map tracks permeability to depths of about 100 meters across the globe.
"This is the first global-scale picture of near-surface permeability, and is based on rock type data at greater depths than previous mapping," says Tom Gleeson, a postdoctoral researcher with the Department of Earth and Ocean Sciences.
Mapping groundwater supplies in such detail is important for managing use of water, especially in where and how much is extracted. Such water source mapping has helped recently in uncovering to what extent groundwater supplies in southern Asia are contaminated with arsenic. Researchers were able to create a 3D map to show that the deeper a well went for water, the more likely it was to be contaminated.
We still don't know exactly how much fresh water we have left, but we know it is shrinking and we are hitting (or have already hit) peak water, since we're draining aquifers, over-exploiting rivers, and dropping the groundwater table ever deeper.
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