Plasmonic device converts light into electricity

By Lisa Zyga

Surface plasmons on the top electrode in the MIM device can increase the current from the top electrode so that it is greater than the current from the bottom electrode, generating a positive net current. Image credit: Wang and Melosh. ©2011 American Chemical Society

While the most common device for converting light into electricity may be photovoltaic (PV) solar cells, a variety of other devices can perform the same light-to-electricity conversion, such as solar-thermal collectors and rectennas. In a new study, engineers have designed a new device that can convert light of infrared (IR) and visible wavelengths into direct current by using surface plasmon excitations in a simple metal-insulator-metal (MIM) device.

The researchers, Fuming Wang and Nicholas A. Melosh of Stanford University, have published their study on the new device in a recent issue of Nano Letters. “The greatest significance thus far is to show an alternative method to rectennas and PV devices for IR and visible light conversion,” Melosh told PhysOrg.com. “The conversion efficiencies aren't amazingly high compared to a PV in visible, so it’s not going to replace PVs, but it could be used for energy scavenging later on.” The new device’s MIM architecture is similar to that of a rectenna. However, whereas rectennas operate with long-wavelength light such as microwaves and radio waves, the new device operates with a broad spectrum of infrared to visible wavelengths. When the MIM device is illuminated, incoming photons are absorbed by the top and bottom metal electrodes. Upon absorption, each photon excites an electron in the metal into a higher energy state so that it becomes a “hot electron.” About half of the hot electrons travel toward the metal-insulator interface, where they may be collected by the other electrode. However, photon absorption in the upper and lower electrodes generates currents with opposite signs, so a net DC current is achieved only if the absorption is larger at one electrode than the other.

Electron transmission in MIM devices (a) with and (b) without surface plasmon excitations. (c) The measured photocurrent in a device with surface plasmons (black line) is higher than in a device without them (red line). Image credit: Wang and Melosh. ©2011 American Chemical Society

This ability to maximize current from one electrode while minimizing it from the other is one of the biggest challenges for MIM devices. To do this, researchers can change the thicknesses of the electrodes. However, there is a tradeoff, since in a thicker electrode, more photons are absorbed but fewer electrons reach the interface due to increased scattering. Wang and Melosh’s solution is to use a prism to excite surface plamons (SPs) on the metal surface of the electrodes when under illumination. The SPs, which are small electron oscillations, can create a higher concentration of hot electrons in one electrode by efficiently coupling to light. The SP coupling efficiency depends on several factors, such as the thickness of the electrode, the type of metal used, and the wavelength of incoming light.

Continue Reading ...
Plasmonic device converts light into electricity
More information: Fuming Wang and Nicholas A. Melosh. “Plasmonic Energy Collection through Hot Carrier Extraction.” Nano Letters, DOI: 10.1021/nl203196z

Related articles

• Light might prompt graphene devices on demand
• Plasmonics Used to Dope Graphene
• Researchers Build Compact Optical Circuit
• Method to improve electric field intensity could boost Raman scattering
• New imaging technique homes in on electrocatalysis of nanoparticles
• Conscious computers are a delusion
• 5 crazy inventions from the mind of Nikola Tesla
• Unlock Your Inner Rain Man by Electrically Zapping Your Brain
• A Skeptic Looks at Alternative Energy

Conscious computers are a delusion

Deutsch: Phrenologie (Photo credit: Wikipedia)

By Raymond Tallis
We have no reason to think computers will be anything other than complex devices that channel unconscious electrical impulses.

The notion that computers can think, or that one day they will do so, is rooted in one of two complementary misunderstandings. The first relates to the nature of computers and the second to the nature of thought. That these misunderstandings have had such a powerful hold on the minds of many otherwise intelligent people is due to a tendency to take useful metaphors – describing what computers do and how they do it – as literal truth.


Consider, first, misunderstanding about the nature of computers. Most people would agree that the computers we have at present are not conscious: the latest Super-Cray with gigabytes of memory is no less zomboid than a pocket calculator. But there is the feeling that at some stage, as a result of increasing computational power and in something called "complexity", the artefact that possesses this power and this complexity will wake up to its own existence, or at the very least, experience the transactions which take place in, through, and around it.

Consciousness Awakening on Vimeo by Ralph Buckley (Photo credit: Ralph Buckley)

We should treat this claim with extreme scepticism because those who say that conscious computers are around the corner are not able to specify what features conscious computers will have in addition to those possessed by our current unconscious ones. There was a fashion in the 1980s and 1990s for invoking alternative architectures – in particular parallel rather than serial processing – as the basis for computers that would be aware of themselves. This fashion has now passed and the conceptual cupboard of the conscious-computers-round-the-corner brigade is now empty. We therefore have no reason for expecting that computers will be anything other than extremely complex devices in which unconscious electrical impulses pass into and out of unconscious electrical circuits and interact with any number of devices connected directly or indirectly to them.

As for thought, this has been even more profoundly misunderstood. Some have argued that thought does not require consciousness, so that computers can think, or will one day think, even though they will never be conscious. Thoughts, like other so-called conscious activities, are merely causal way-stations between inputs such as sense experience and outputs such as behaviour. They do not have to be conscious; indeed, consciousness contributes nothing to their causal efficacy. It requires no equipment or subtle argument to demonstrate that this is nonsense. All you need is to focus on the thoughts you are having now. To deny that thought is conscious is self-refuting: you cannot deny the consciousness of your thoughts without being conscious of doing so. And to claim that conscious thought, or indeed consciousness, has a central role in our lives belongs to an extreme behaviourism that is not able to explain even ordinary human behaviour.

Continue Reading ...
Conscious computers are a delusion | Raymond Tallis | Comment is free | guardian.co.uk

Related articles

• Don't Innovate, Imitate
• Jennifer Egan, "Black Box" : The New Yorker
• 'V' is for Defeat: The Total and Utter Annihilation of Representational Theories of Mind
• Could the Internet Become Conscious like the Human Brain?
• The Insanity Defense: An Intersection of Morality, Public Policy, and Science
• 5 crazy inventions from the mind of Nikola Tesla
• Don't Innovate, Imitate

Sex is best when you lose your head

Review by James Meek

• Promiscuity: An Evolutionary History of Sperm Competition and Sexual Conflict by Tim Birkhead
  
  Faber, 272 pp, £9.99, May 2000, ISBN 0 371 19360 5

In 1853 the Reverend Frederick Morris, an opponent of Charles Darwin’s and a man with a Victorian sense of propriety, urged his parishioners to emulate the fidelity of a small bird called the dunnock. Be thou like the dunnock, he told them – the female and the male impeccably faithful to each other.

Charles Robert Darwin. A copy made by John Collier (1850-1934) in 1883 of his 1881 portrait of Charles Darwin. According to Darwin's son Erasmus, "The picture is a replica of the one in the rooms in the Linnaean Society and was made by Collier after the original. I took some trouble about it and as a likeness it is an improvement on the original." Given to the National Portrait Gallery, London in 1896. See source website for additional information. (Photo credit: Wikipedia)

What would the Rev. Morris have made of the scandalous truth? Far from being monogamous, the dunnocks, from a Victorian point of view, have shockingly lax morals. The female dunnock often takes not one but two males as partners. The best a stern man of religion could say about dunnocks is that there’s no superfluous bump and grind when they mate – it’s strictly fertilisation business, over in 0.1 seconds. Fast enough to do it while your mother’s back is turned.

Tim Birkhead and his fellow evolutionary biologists, exploring the nature of sexuality across species from single-celled organisms to humankind, are the paparazzi of the science world. They travel to remote islands and put up with extreme discomfort in the hope of catching animals having sex with each other, and when they do, splash their names and their pictures over the pages of the science journals. It doesn’t always work out. Fiona Hunter and a colleague, later to expose what the mainstream media dubbed ‘penguin prostitution’ in the Antarctic, once watched a colony of fulmars on Fair Isle for 56 days on the trot, 18 hours a day, only to find the species relatively faithful: a mere 16 per cent of females had sex with a bird who wasn’t their partner, and there were no ‘illegitimate’ chicks. This isn’t a glamorous pursuit. Geoff Parker, one of the human heroes of Birkhead’s story, spent months with his face a few centimetres away from fresh cowpats, watching female dungflies being aggressively mounted by two males in turn. Sometimes the biologists witness scenes more disturbing than they had anticipated: Mats Olsson, observing the rape-like mating of the Lake Eyre dragon in Australia, saw a male lizard bite his female victim so hard while impregnating her that she died.

Often it is not enough to be a mere voyeur with a long lens. Like a manipulative aristocrat in a Jacobean drama, the intrepid investigator arranges things: Birkhead gets live zebra finches to mate with dead ones, Nicholas Davies and Ian Hartley make it possible for female dunnocks to take a third husband.

A Dunnock, Prunella modularis, photographed in Torquay, Devon, England in April 2008. (Photo credit: Wikipedia)

Decades of accumulated work of this kind have changed our understanding of the nature of sex, reproduction and the different roles of male and female. From Darwin’s time up to the late 1960s – not coincidentally, the time when the intellectual assault on male-centred academic thinking got under way in earnest – it was thought that male animals competed for female partners, with the strongest and most attractive impregnating the most females; that females sought only monogamy, and if they did have sex with multiple partners (and biologists couldn’t help noticing that they did) it was against their will, always a form of submission to rape.
In the past thirty years, the conventional wisdom has been destroyed. The truth is that females of most species actively seek multiple partners to have sex with. If the aim of males is to put their sperm into as many females as possible, females are trying, with equal determination, to get the very best sperm to fertilise their eggs – even if that means having sex with many males in turn.

Rivalry between males and discrimination by females extends beyond the sexual act itself. Inside the female, the sperm of different males fight for supremacy – this is sperm competition. At the same time, the female may be able to select the sperm that are best for her – this is sperm choice. This is the true battle of the sexes. The males and females of each species are permanently locked in a struggle to out-evolve each other as their reproductive equipment and behaviour change to achieve their conflicting aims – i.e. maximum fertilisation v. best fertilisation.

The Hidden Truths about Calories

By Rob Dunn

Odds are you sometimes think about calories. They are among the most often counted things in the universe. When the calorie was originally conceived it was in the context of human work. More calories meant more capacity for work, more chemical fire with which to get the job done, coal in the human stove. Fat, it has been estimated, has nine calories per gram, whereas carbohydrates and proteins have just four; fiber is sometimes counted separately and gets awarded a piddling two. Every box of every food you have ever bought is labeled based on these estimates; too bad then that they are so often wrong.

A Food is Not a Food—Estimates of the number of calories in different kinds of foods measure the average number of calories we could get from those foods based only on the proportions of fat, carbohydrates, protein and sometimes fiber they contain (In essence, calories ingested minus calories egested). A variety of standard systems exist, all of which derive from the original developed by Wilbur Atwater more than a hundred years ago. They are all systems of averages. No food is average.

Differences exist even within a given kind of food. Take, for example, cooked vegetables. Cell walls in some plants are tougher to break down than those in others; nature, of course, varies in everything. If the plant material we eat has more of its cell walls broken down we can more of the calories from the goodies inside. In some plants, cooking ruptures most cell walls; in others, such as cassava, cell walls hold strong and hoard their precious calories in such a way that many of them pass through our bodies intact.
It is not just cooked vegetables though. Nuts flagrantly do their own thing, which might be expected given that nuts are really seeds whose mothers are invested in having them escape digestion. Peanuts, pistachios and almonds all seem to be less completely digested than their levels of protein, fat, carbohydrates and fiber would suggest. How much? Just this month, a new study by Janet Novotny and colleagues at the USDA found that when the “average” person eats almonds she receives just 128 calories per serving rather than the 170 calories “on the label.”

[Image 1. Some of the calories our bodies do not digest go to the dung beetles
and flies whose empire rises around our inefficiencies.
Photo of the species Garreta nitens by Piotr Naskrecki]

It is not totally clear why nuts such as almonds or pistachios yield fewer calories than they “should.” Tough cell walls? Maybe. But there are other options too, if not for the nuts themselves then for other foods.

For one, our bodies seem to expend different quantities of energy to deal with different kinds of food (the energy expended produces heat and so is referred to by scientists as “diet-induced thermogensis”); some foods require us to do more work than others. Proteins can require ten to twenty times as much heat-energy to digest as fats, but the loss of calories as heat energy is not accounted for at all on packaging.

5 crazy inventions from the mind of Nikola Tesla

Earthquake machines! Death rays! Those far-fetched gadgets are part of a plan to build a museum dedicated to one of history's most famous mad scientists

Early 20th century inventor Nikola Tesla was ahead of his time with concepts that ranged from x-rays to robotics. Photo: Herbert Barraud/Getty Images

Nikola Tesla signature (Photo credit: Wikipedia)

Matthew Inman, proprietor of web comic The Oatmeal, is on a mission to build a crowd-funded museum dedicated to inventor Nikola Tesla, who Inman refers to as "the greatest geek who ever lived." Inman's goal was to raise $850,000 (which would be matched dollar-for-dollar by a New York state grant) in 45 days. But surprisingly, a little more than a week into it, the online campaign has gathered more than $1.1 million in donations. Many of the inventor's fans think Tesla was more brilliant than his more famous contemporaries, including Alexander Graham Bell and Thomas Edison. Even though Tesla isn't exactly a household name, his unsung accomplishments and wild imagination have turned him into something of a folk hero. Here, a rundown of five of Tesla's craziest inventions:

Wireless transmission of power and energy demonstration during his high frequency and potential lecture of 1891 (Photo credit: Wikipedia)

1. Wireless energy transfer
About 120 years ago at the 1893 World Fair in Chicago, Tesla demonstrated that you could wirelessly transmit electricity by firing up a series of phosphorous light bulbs in a process he called electrodynamic induction. He dreamed that such technology would allow us to one day shoot power over long distances in the atmosphere, supplying distant destinations with the energy needed to live comfortably. Now over a century later, companies such as Intel and Sony are interested in applying the non-radiative energy transfer to things such as cell phones to allow you to charge your battery without messy power cables.

2. X-raysTesla's research in the field of electromagnetism helped give radiologists everywhere the ability to peer into a person's anatomy without cutting them open — a concept that, in the late 1800s, sounded far-fetched. Although German physicist Willhelm Röntgen is widely credited with the discovery of X-rays in 1895, Tesla's own experiments with the technology eight years prior highlighted some of the inherent dangers of using radiation on human flesh.

3. Death ray
In the 1930s Tesla reportedly invented a particle beam weapon that some, ironically, called a "peace ray," says Lauren Davis at io9. "The device was, in theory, capable of generating an intense targeted beam of energy" that could be used to dispose of enemy warplanes, foreign armies, "or anything else you'd rather didn't exist." The so-called "death ray" was never constructed, however, even though Tesla shopped the device around to various military divisions. The plans for the laser were never found after Tesla's death.

4. Robotics
Tesla imagined that, in the future, a race of robots "would be able to perform labor safely and effectively," says io9's Davis. In 1898, he demonstrated a radio-controlled boat he'd invented, which many credit as "being the birth of robotics." He envisioned a world filled with "intelligent cars, robotic human companions, [various] sensors, and autonomous systems."

5. Earthquake machine
"In 1898, Tesla claimed he had built and deployed a small oscillating device that, when attached to his office and operating, nearly shook down the building and everything around it," says Shea Gunther at Revmodo. The device weighed just a few pounds, but Tesla was able to tune the timing of the oscillator at such a frequency that each little vibration added just a little more energy to the wave of flex in the building. "Given enough little pushes, even the largest structure could be shaken apart." Realizing the potential terrors such a device could create, "Tesla said he took a hammer to the oscillator to disable it, instructing his employees to claim ignorance to the cause of the tremors if asked."

Source, Maximum PC, RSNA.org, An Engineer's Aspect, io9, Activist Post, Revmodo

Related articles

• Nikola Tesla gets his own museum, thanks to cartoonist
• David Blaine Mines Nikola Tesla's Playbook for His Latest Stunt
• Long Island Laboratory Of Nikola Tesla To Be Restored And Turned Into Museum
• Preservation Success: Nikola Tesla Wardenclyffe Tower
• Don't Innovate, Imitate
• A Point of View: What would Keynes do?

Can quantum theory be improved?

by Lisa Zyga

A source emits two spin-half particles traveling to two distant sites where each particle’s spin is measured by a detector. If the particles are initially maximally entangled, then the probability of correctly predicting the result of the measurement on either one of the entangled particles is, according to quantum mechanics, 0.5. Image credit: Stuart, et al. ©2012 American Physical Society

Being correct 50% of the time when calling heads or tails on a coin toss won’t impress anyone. So when quantum theory predicts that an entangled particle will reach one of two detectors with just a 50% probability, many physicists have naturally sought better predictions. The predictive power of quantum theory is, in this case, equal to a random guess. Building on nearly a century of investigative work on this topic, a team of physicists has recently performed an experiment whose results show that, despite its imperfections, quantum theory still seems to be the optimal way to predict measurement outcomes.

The physicists, Terence E. Stuart, et al., from the University of Calgary in Alberta, Canada; ETH Zurich in Switzerland; and the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, have published their paper on the predictive power of quantum theory and alternative theories in a recent issue of Physical Review Letters.

“The fact that certain outcomes can only be predicted with probability 50% by quantum theory could in principle be explained in two very different ways,” coauthor Renato Renner of ETH Zurich told Phys.org. “One would be that quantum theory is an incomplete theory whose predictions are only random because we have not yet discovered the parameters that are relevant for determining the outcomes (and that another yet-to-be-discovered theory would therefore allow for better predictions). The other explanation would be that there is ‘inherent’ randomness in Nature. Our work excludes the first possibility. In other words, it is not only quantum theory that predicts randomness, but there is ‘real’ randomness in Nature.”

The physicists began by asking whether it may be possible to improve quantum theory’s predictive power by supplementing it with some additional information (i.e., a local hidden variable). With complete information about a scenario, classical theories can predict an outcome with 100% accuracy. But in the 1960s, physicist John Bell proved that no local hidden variable exists that could enable quantum theory to predict an outcome with complete certainty.

However, Bell’s work didn’t rule out the possibility that quantum theory’s predictive power could be improved a little bit, nor did it refute the existence of any alternative probabilistic theory that has more predictive power than quantum theory.

One recent proposal for improving quantum mechanical prediction was suggested by physicist Tony Leggett in 2003. In this model, a hidden spin vector could increase the predictive probability of quantum theory by 0.25, from 0.5 to 0.75 (with 1.0 being complete certainty). Although Leggett showed that this model is incompatible with quantum theory, there has been no reason to assume that other models don’t exist.
Read more...

Related articles

• NIST Demonstrates First Quantum 'Entanglement' of Ions Using Microwaves
• New combination of nanoparticles and graphene results in a more durable catalytic material for fuel cells
• High-performance capacitor could lead to better rechargeable batteries
• Interstellar Travel Not Possible Before 2200AD, Suggests Study
• What's That? Your Physics Questions Answered
• Quantum causal relations: A causes B causes A
• Where Did Quantum Theory Come From? [Video]
• The birth of quantum theory (deliciously, it involves cookies) [Video]
• Quantum Theory and Its Relevance in the Retail Marketplace
• Why Quantum Theory Is So Misunderstood - Speakeasy - WSJ #science

Why Procrastination is Good for You

By Megan Gambino

In a new book, University of San Diego professor Frank Partnoy argues that the key to success is waiting for the last possible moment to make a decision

 In his new book, Wait: The Art and Science of Delay, Frank Partnoy claims that when faced with a decision, we should assess how long we have to make it, and then wait until the last possible moment to do so.
Book jacket: Courtesy of Pete Garceau; Portrait: Courtesy of Fergus Greer

Sometimes life seems to happen at warp speed. But, decisions, says Frank Partnoy, should not. When the financial market crashed in 2008, the former investment banker and corporate lawyer, now a professor of finance and law and co-director of the Center for Corporate and Securities Law at the University of San Diego, turned his attention to literature on decision-making.
“Much recent research about decisions helps us understand what we should do or how we should do it, but it says little about when,” he says.
In his new book, Wait: The Art and Science of Delay, Partnoy claims that when faced with a decision, we should assess how long we have to make it, and then wait until the last possible moment to do so. Should we take his advice on how to “manage delay,” we will live happier lives.

The Codex of Alchemical Engineering [game]

Wanted to share "The Codex of Alchemical Engineering", which is a great Flash game!

Like Alchemy, but More Tangible!

The Codex of Alchemical Engineering is a puzzle game about programming “manipulators” to move, transmute, and bind alchemical “atoms” into complex compounds.
A few notes about the game:

• After completing a level, your progress is saved so long as your Flash “cookies” aren’t deleted. Your design, however, is not; if you want to keep your design, you must go to the Save screen and save the text shown there (I keep my solutions in a text file on my desktop). You can reload a saved design by pasting the design code into the Load window and pressing the load button.
• The music playing is Evan’s “Rever… Peut-etre…”, which you can find here on jamendo.com.

Requires: Flash