Definitions of quantum computers
Since the world is quantum, any computer is a quantum computer. Conventional computers are just weak quantum computers, since they don’t exploit intrinsically quantum effects, such as superposition and entanglement.
A quantum computer is a computer that uses intrinsically quantum effects that cannot naturally be modeled by classical physics. Classical computers may be able to mathematically simulate instances of such computers, but they are not implementing the same kinds of quantum operations.
Definition 2, where there are strong tests or proofs of the quantum effects at play (e.g. by doing Bell tests).
A quantum computer is a computer that uses intrinsically quantum effects to gain some advantage over the best known classical algorithms for some problem.
A quantum computer is a computer that uses intrinsically quantum effects to gain an asymptotic speed-up over the best known classical algorithms for some problem. (The difference with definition 3 is that the advantage is a fundamental algorithmic one that grows for larger instances of the problem; versus advantages more closely tied to hardware or restricted to instances of some bounded size.)
A quantum computer is a computer that is able to capture the full computational power of quantum mechanics, just as conventional computers are believed to capture the full computational power of classical physics. This means, e.g. that it could implement any quantum algorithm specified in any of the standard quantum computation models. It also means that the device is in principle scalable to large sizes so that larger instances of computational problems may be tackled.
by Michele Mosca
Jurij Gagarin - From up Here… the Earth is Beautiful
The Möbius strip or Möbius band is a surface with only one side and only one boundary component. The Möbius strip has the mathematical property of being non-orientable. It can be realized as a ruled surface. It was discovered independently by the German mathematicians August Ferdinand Möbius and Johann Benedict Listing in 1858.
The economic power of the Golden Rice opposition
One of the most interesting fact about the golden rice affair is that this particular genetically modified organism is developed by public research, and not by the industrial reserach:
Rice (Oryza sativa), a major staple food, is usually milled to remove the oil-rich aleurone layer that turns rancid upon storage, especially in tropical areas. The remaining edible part of rice grains, the endosperm, lacks several essential nutrients, such as provitamin A. Thus, predominant rice consumption promotes vitamin A deficiency, a serious public health problem in at least 26 countries, including highly populated areas of Asia, Africa, and Latin America. Recombinant DNA technology was used to improve its nutritional value in this respect. A combination of transgenes enabled biosynthesis of provitamin A in the endosperm.
Ye X. Engineering the Provitamin A (-Carotene) Biosynthetic Pathway into (Carotenoid-Free) Rice Endosperm, Science, 287 (5451) 303-305. DOI: 10.1126/science.287.5451.303
David Ropeik, on Scientific American, wrote an interesting article about the opposition to the introduction of golden rice strating from a paper published at the beginning of this year:
Vitamin A enriched rice (Golden Rice) is a cost-efficient solution that can substantially reduce health costs. Despite Golden Rice being available since early 2000, this rice has not been introduced in any country. Governments must perceive additional costs that overcompensate the benefits of the technology to explain the delay in approval. We develop a real option model including irreversibility and uncertainty about perceived costs and arrival of new information to explain a delay in approval. The model has been applied to the case of India. Results show the annual perceived costs have to be at least US$199 million per year approximately for the last decade to explain the delay in approval of the technology. This is an indicator of the economic power of the opposition towards Golden Rice resulting in about 1.4 million life years lost over the past decade in India.
Golden Rice could be a key role in particular in Philippine and since 2003 it seemed a good solution to malnutrition problem of that population (Nature - pdf).
So, although in some paragraphs Ropeik’s article sounds a bit terroristic, I think that the opposition to the public GMOs is probably excessive.
Image credit: Commons
This new Hubble image is centered on NGC 5793, a spiral galaxy over 150 million light-years away in the constellation of Libra. This galaxy has two particularly striking features: a beautiful dust lane and an intensely bright center — much brighter than that of our own galaxy, or indeed those of most spiral galaxies we observe.
NGC 5793 is a Seyfert galaxy. These galaxies have incredibly luminous centers that are thought to be caused by hungry supermassive black holes — black holes that can be billions of times the size of the sun — that pull in and devour gas and dust from their surroundings. This galaxy is of great interest to astronomers for many reasons. For one, it appears to house objects known as masers. Whereas lasers emit visible light, masers emit microwave radiation. The term “masers” comes from the acronym Microwave Amplification by Stimulated Emission of Radiation. Maser emission is caused by particles that absorb energy from their surroundings and then re-emit this in the microwave part of the spectrum.
Naturally occurring masers, like those observed in NGC 5793, can tell us a lot about their environment; we see these kinds of masers in areas where stars are forming. In NGC 5793 there are also intense mega-masers, which are thousands of times more luminous than the sun.
Credit: NASA, ESA, and E. Perlman (Florida Institute of Technology)
Deep shadows create dramatic contrasts between light and dark in this high-resolution close-up of the martian surface. Recorded on January 24 by the HiRISE camera onboard the Mars Reconnaissance Orbiter, the scene spans about 1.5 kilometers across a sand dune field in a southern highlands crater. Captured when the Sun was just 5 degrees above the local horizon, only the dune crests are caught in full sunlight. With the long, cold winter approaching the red planet’s southern hemisphere, bright ridges of seasonal frost line the martian dunes.
Image Credit: HiRISE, MRO, LPL (U. Arizona), NASA
A powerful storm passed over New Zealand’s South Island in March 2014 and brought gale-force winds, torrential rains, and flooding to the city of Christchurch. A total of 74 millimeters (3 inches) of rain fell on March 4-5, according to MetService, New Zealand’s national meteorological service. More than 100 homes flooded and more than 4,000 lost power around the country’s third most populous city. Skies had cleared enough by March 6, 2014, for the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite to acquire this image showing the aftermath.
Coastal communities are becoming increasingly vulnerable to the risk of damage and danger from flooding. NASA and NOAA are together launching a new opportunity for citizens to work with us on the very important topic of coastal flooding. This coastal flooding challenge is part of NASA’s third International Space Apps Challenge - a two-day global mass collaboration event on April 12-13, 2014. During these two days, citizens around the world are invited to engage directly with NASA to develop awe-inspiring software, hardware, and data visualizations. Last year’s event involved more than 9,000 global participants in 83 locations. This year will introduce more than 60 robust challenges clustered in five themes: asteroids, Earth watch, human spaceflight, robotics, and space technology. The Coastal Inundation In Your Community challenge is one of four climate-related challenges using data provided by NASA, NOAA and EPA.
Image Credit: NASA - Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC
At about 89,000 miles in diameter, Jupiter could swallow 1,000 Earths. It is the largest planet in the solar system and perhaps the most majestic. Vibrant bands of clouds carried by winds that can exceed 400 mph continuously circle the planet’s atmosphere. Such winds sustain spinning anticyclones like the Great Red Spot — a raging storm three and a half times the size of Earth located in Jupiter’s southern hemisphere. In January and February 1979, NASA’s Voyager 1 spacecraft zoomed toward Jupiter, capturing hundreds of images during its approach, including this close-up of swirling clouds around Jupiter’s Great Red Spot. This image was assembled from three black and white negatives. The observations revealed many unique features of the planet that are still being explored to this day.
Credit: NASA’s Goddard Space Flight Center. Video and images courtesy of NASA/JPL
In celebration of the 24th anniversary of the launch of NASA’s Hubble Space Telescope, astronomers have captured infrared-light images of a churning region of star birth 6,400 light-years away.
This colorful Hubble Space Telescope mosaic of a small portion of the Monkey Head Nebula unveils a collection of carved knots of gas and dust silhouetted against glowing gas. The cloud is sculpted by ultraviolet light eating into the cool hydrogen gas.
Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)