Titanium is the leading material for artificial knee and hip joints because it’s strong, wear-resistant, and nontoxic, but adding gold might make implants even better.
“It is about 3-4 times harder than most steels,” says Emilia Morosan, the lead scientist of a new study in Science Advances that describes the properties of a 3-to-1 mixture of titanium and gold with a specific atomic structure that imparts hardness. “It’s four times harder than pure titanium, which is what’s currently being used in most dental implants and replacement joints.”
The new study is “a first for me in a number of ways,” says Morosan, professor of physics and astronomy, of chemistry, and of materials science and nanoengineering at Rice University. “This compound is not difficult to make, and it’s not a new material.”
In fact, the atomic structure of the material—its atoms are tightly packed in a “cubic” crystalline structure that’s often associated with hardness—was previously known.
It’s not even clear that Morosan and former graduate student and coauthor Eteri Svanidze were the first to make a pure sample of the ultrahard “beta” form of the compound. But due to a couple of lucky breaks, they are the first to document the material’s remarkable properties.
“This began from my core research,” says Morosan, a physicist who specializes in the design and synthesis of compounds with exotic electronic and magnetic properties. “We published a study not long ago on titanium-gold, a 1-to-1 ratio compound that was a magnetic material made from nonmagnetic elements.
“One of the things that we do when we make a new compound is try to grind it into powder for X-ray purposes. This helps with identifying the composition, the purity, the crystal structure, and other structural properties. When we tried to grind up titanium-gold, we couldn’t. I even bought a diamond (coated) mortar and pestle, and we still couldn’t grind it up.”
4x harder than titanium
The researchers decided to do follow-up tests to determine exactly how hard the compound was, and while they were at it, they also decided to measure the hardness of the other compositions of titanium and gold that they had used as comparisons in the original study.
One of the extra compounds was a mixture of three parts titanium and one part gold that had been prepared at high temperature.
What they didn’t know at the time was that making titanium-3-gold at relatively high temperature produces an almost pure crystalline form of the beta version of the alloy—the crystal structure that’s four times harder than titanium.
At lower temperatures, the atoms tend to arrange in another cubic structure—the alpha form of titanium-3-gold. The alpha structure is about as hard as regular titanium. It appears that labs that had previously measured the hardness of titanium-3-gold had measured samples that largely consisted of the alpha arrangement of atoms.
Researchers measured the hardness of the beta form of the crystal and also performed other comparisons with titanium. For biomedical implants, for example, two key measures are biocompatibility and wear resistance. Because titanium and gold by themselves are among the most biocompatible metals and are often used in medical implants, the team believed titanium-3-gold would be comparable.
In fact, tests determined that the new alloy was even more biocompatible than pure titanium. The story proved much the same for wear resistance: Titanium-3-gold also outperformed pure titanium.
Other scientists from Rice and from Texas A&M University and Florida State University are coauthors of the study that was supported by the National Science Foundation, the Department of Energy, Texas A&M’s Turbomachinery Laboratory, and the Florida State University Research Foundation. Their research is publisehed in Science Advances.
Much of the current research on the development of a quantum computer involves work at very low temperatures. The challenge to make them more practical for everyday use is to make them work at room temperature.
The breakthrough here came from the use of some everyday materials, with details published today in Nature Communications.
A typical modern-day computer represents information using a binary number system of discrete bits, represented as either 0 and 1.
A quantum computer uses a sequence of quantum bits, or qubits. They can represent information as 0 or 1 or any of a series of states between 0 and 1, known as quantum superposition of those qubits.
It’s this leap that makes quantum computers capable of solving problems much more quickly and powerfully than today’s typical computers.
All in the spin
An electron has a charge and a spin – the spin determines if an atom will generate a magnetic field. The spin can also be used as a qubit as it can undergo transitions between the spin-up and spin-down quantum states, represented classically by 0 and 1.
But the electron spin states therefore need to be robust against “decoherence”. This is the disordering of the electron spins during quantum superposition which results in the loss of information.
The electron spin lifetimes are affected by lattice vibrations in a material and neighbouring magnetic interactions. Long electron spin lifetimes exceeding 100 nanoseconds are needed for quantum computing.
Cooling a material to low temperatures close to absolute zero, -273C, does increases the spin lifetime. So too does the use of magnetically pure conducting materials.
So quantum devices using atomically heavy materials such as silicon or metals need to be cooled to low temperatures near absolute zero.
Other materials have been used to perform quantum manipulations at room temperature. But these materials need to be isotopically engineered, which requires large facilities like nuclear reactors, and pose limitations around qubit density.
Molecules such as metal-organic cluster compounds have also been used, but they too require low temperatures and isotopic engineering.
There are clear and established trade-offs to be considered regarding the feasibility of applying a qubit material system for quantum computing.
A conducting material of light atomic weight with a long electron spin lifetime exceeding 100 nanoseconds at room temperature would permit practical quantum computing. Such a material would combine the best aspects of current solid-state material qubit schemes.
Why you need mothballs
We have demonstrated that a long conduction electron spin lifetime in metallic-like material made up of carbon nanospheres can be achieved at room temperature.
This material was produced simply by burning naphthalene, the active ingredient in mothballs.
The material is produced as a solid powder and handled in air. It can then be dispersed in ethanol and water solvents, or deposited directly onto a surface like glass. As the material was remarkably homogeneous, the measurements could be made on the bulk solid powder.
This allowed us to achieve a new record electron spin lifetime of 175 nanoseconds at room temperature. This might not sound like a long time, but it exceeds the prerequisite for applications in quantum computing and is about 100 times longer than that found in graphene.
This was possibly due to the materials’ self-doping of conduction electrons and their nanometre spatial confinement. This basically means the spheres could be made entirely from carbon while preserving their unique electronic property.
Our work now opens the possibility for spin qubits to be manipulated in a conducting material at room temperature. This method doesn’t need any isotopic engineering of a host material, dilution of the spin-carrying molecule, or cryogenic temperatures.
It allows a higher density packing of qubits to be, in principle, achieved over other promising qubits like those used in silicon.
This very easy preparation of a carbon material using common laboratory reagents reduces many of the technological barriers to realising practical quantum computing.
For example, the refrigeration systems required to cool materials close to absolute zero can cost upwards of millions of dollars and occupy physical spaces the size of large rooms.
To build a quantum computer one would need to demonstrate that qubits can undergo manipulations involving the superposition of quantum states and also to a build a functioning quantum logic gate (switch).
In our work we have demonstrated the former while making the latter a question of engineering rather than breakthrough science. The next step would be to build a quantum logic gate – an actual device.
What is exciting is that the material is prepared in a form suitable for device processing. We have already demonstrated that the individual conducting carbon nanospheres can be isolated on a silicon surface.
In principal, this may provide an initial avenue to high-density qubit arrays of nanospheres that are integrated onto existing silicon technologies or thin-film-based electronics.
Despite substantial conservation efforts, human impacts are harming coral reefs all over the world. That in turn affects the millions of people who depend on reefs for their livelihoods. It’s a gloomy picture, but there are some bright spots.
In a study that appears on the cover of this week’s Nature, I and 38 international colleagues identify 15 places around the world where the outlook is not so bleak. Many of them are in surprising places like Pacific island states, which may not have lots of money for conservation but do have a close social connection to the health of their oceans.
Unlike scientific studies that look at averages or trends, we took a slightly different approach and focused on the outliers – the places bucking the trend. This type of “bright spot” approach has been used in a range of fields, including business, health and human development, to search for hope against backgrounds of widespread failure.
This is a great example of local habits that, once identified and spread more widely, have had a hugely beneficial impact. My colleagues and I wanted to see if we could do the same for the world’s coral reefs.
Searching for bright spots
We carried out more than 6,500 reef surveys across 46 countries, states and territories around the world and looked for places where reef fisheries should have been degraded, but weren’t.
We defined these bright spots as reefs with more fish than expected, based on their exposure to pressures like human population, poverty and unfavourable environmental conditions. To be clear, bright spots are not necessarily “pristine” reefs, but rather reefs that are doing better than they should be given the circumstances. They are reefs that are “punching above their weight”.
We identified 15 bright spots and 35 dark spots (places that were doing much worse than expected) in our global survey. The bright spots were mainly in the Pacific Ocean, and two-thirds of them were in populated places like the Solomon Islands, parts of Indonesia, Papua New Guinea and Kiribati.
Dark spots were more globally distributed; we found them in every major ocean, sometimes in places that are generally considered to be pristine, such as in the northwestern Hawaiian islands. Again, this doesn’t mean the reefs were necessarily in terrible shape – just worse than we would expect, given that in cases such as Hawaii they are remote, well protected and in a wealthy country with a strong capacity to govern their reefs.
The Great Barrier Reef, which is often considered the best-managed reef in the world, performed largely as we would expect it to, given that it is in a wealthy country with low population density, and many of its individual reefs are offshore and mostly remote from people.
What makes bright spots special?
We wanted to learn what these bright spots were doing differently. Why were they able to withstand pressures that caused other reef systems to suffer? And could lessons from these places inform reef conservation in other areas?
Our preliminary investigation showed that bright spots (and their nearby human communities) generally had four crucial characteristics:
high levels of participation in management by local people
high levels of dependence on fishing (this seems counter-intuitive, but research shows that where people’s livelihoods depend on a resource, they are more committed to managing it responsibly)
deep-water refuges for fish and corals.
Importantly, the first two are malleable (for instance, governments can invite local people to become more involved with reef management), whereas the latter two are less so (it is hard to change people’s livelihoods, and impossible to change the undersea landscape in a way that wouldn’t devastate reefs in the process).
We also found some common characteristics of dark spots
use of particular types of fishing nets that can damage habitat
widespread access to freezers, allowing fish catches to be stockpiled
a recent history (within the past five years) of environmental disturbance such as coral bleaching or cyclone.
We believe that the bright spots offer some hope and some solutions that can be applied more broadly across the world’s coral reefs.
Specifically, investments that foster local involvement and provide people with ownership rights to their marine resources can help people develop creative solutions and defy expectations that reefs will just continue to get more degraded.
Conversely, dark spots can highlight the development or management pathways to avoid. In particular, it is important to avoid investing in technology that allows for more intensive fishing, particularly in places with weak governance or where there have already been environmental shocks like cyclones or bleaching.
The next step is to dig deeper into the social, institutional and ecological dynamics in the bright spots. By looking to the places that are getting it right – whether by accident or design – we can hopefully make the future a bit brighter for reefs the world over.
Indeed, it seems as though before we can even finish mourning the loss of one pop star, another falls. There’s no shortage of groundbreaking artists who die prematurely, whether it’s Michael Jackson, Elvis Presley or Hank Williams.
As a physician, I’ve begun to wonder: Is being a superstar incompatible with a long, healthy life? Are there certain conditions that are more likely to cause a star’s demise? And finally, what might be some of the underlying reasons for these early deaths?
To find out the answer to each of these questions, I analyzed the 252 individuals who made Rolling Stone’s list of the 100 greatest artists of the rock & roll era.
More than their share of accidents
To date, 82 of the 252 members of this elite group have died.
There were six homicides, which occurred for a range of reasons, from the psychiatric obsession that led to the shooting of John Lennon to the planned “hits” on rappers Tupac Shakur and Jam Master Jay. There’s still a good deal of controversy about the shooting of Sam Cooke by a female hotel manager (who was likely protecting a prostitute who had robbed Cooke). Al Jackson Jr., the renowned drummer with Booker T & the MGs, was shot in the back five times in 1975 by a burglar in a case that still baffles authorities.
An accident can happen to anyone, but these artists seem to have more than their share. There were numerous accidental overdoses – Sid Vicious of the Sex Pistols at age 21, David Ruffin of the Temptations at 50, The Drifters’ Rudy Lewis at 27, and country great Gram Parsons, who was found dead at 26.
And while your odds of dying in a plane crash are about one in five million, if you’re on Rolling Stone’s list, those odds jump to one in 84: Buddy Holly, Otis Redding and Ronnie Van Zant of the Lynyrd Skynyrd Band all died in airplane accidents while on tour.
It’s likely tied to the elevated alcohol and drug use among artists. Liver bile duct cancers – which are extremely rare – happened to two of the top 100, with Ray Manzarek of The Doors and Tommy Ramone of the Ramones both succumbing prematurely from a cancer that normally affects one in 100,000 people a year.
The vast majority of those on Rolling Stone’s list were born in the 1940s and reached maturity during the 1960s, when tobacco smoking peaked. So not surprisingly, a significant portion of artists died from lung cancer: George Harrison of the Beatles at age 58, Carl Wilson of the Beach Boys at 51, Richard Wright of Pink Floyd at 65, Eddie Kendricks of the Temptations at 52 and Obie Benson of the Four Tops at 69. Throat cancer – also linked with smoking – caused the deaths of country great Carl Perkins at 65 and Levon Helm of The Band at 71.
A good number from the list had heart attacks or heart failure, such as Ian Stewart of the Rolling Stones at 47 and blues greats Muddy Waters at 70, Howlin Wolf at 65, Roy Orbison at 52 and Jackie Wilson at 49.
Currently, the U.S. is in the midst of an opioid abuse epidemic, with heroin and prescription drug overdoses happening at historic rates.
But for rock stars, opioid abuse is nothing new. Elvis Presley, Jimi Hendrix, Janis Joplin, Sid Vicious, Gram Parsons, Whitney Houston (who didn’t make the list), Michael Jackson and now Prince all died from accidental opioid overdoses.
Factoring in their birth year and a life expectancy of 76 years, only 44 should have died by now. Instead, 82 have. (Incidentally, of the 44 we would have expected to be dead by now, 19 are still alive.)
The second shocking discovery was the sobering and disproportional
occurrence of alcohol- and drug-related deaths.
There was Kurt Cobain’s gunshot suicide while intoxicated and Duane Allman’s drunk driving motorcycle crash. Members of legendary bands like The Who (John Entwistle, 57, and Keith Moon, 32), The Doors (Jim Morrison, 27), The Byrds (Gene Clark, 46, and Michael Clarke, 47) and The Band (Rick Danko, 55, and Richard Manuel, 42) all succumbed to alcohol or drugs.
Others – The Grateful Dead’s Jerry Garcia and country star Hank Williams – steadily declined from substance abuse while their organs deteriorated. Their official causes of death were heart-related. In truth, the cause may have been more directly related to substance abuse.
In all, alcohol and drugs accounted for at least one in 10 of these great artists’ deaths.
Does a quest for fame lead to an early demise?
Many have explored the root causes behind these premature deaths.
One answer may come from dysfunctional childhoods: experiencing physical or sexual abuse, having a depressed parent or having a family broken up by tragedy or divorce. An article published in the British Medical Journal found that “adverse childhood experiences” may act as a motivator to become successful and famous as a way to move past childhood trauma.
The authors noted an increased incidence of these adverse childhood experiences among famous artists. Unfortunately, the same adverse experiences also predispose people to depression, drug use, risky behaviors and premature death.
A somewhat similar hypothesis is proposed by the Self Determination Theory, which addresses human motivation through the lens of “intrinsic” versus “extrinsic” life aspirations. People who have intrinsic goals seek inward happiness and contentment. On the other hand, people who possess extrinsic goals focus on material success, fame and wealth – the exact sort of thing attained by these exceptional artists. According to research, people who have extrinsic goals tend to have had less-involved parents and are more likely to experience bouts of depression.
By following the relationship between genius and mental illness, mental illness and substance abuse, and then substance abuse, health problems and accidental death, you can see why so many great artists seem almost destined for a premature or drug-induced demise.
As voters go to the polls this November, at least four states will consider ballot questions on marijuana legalization. Pending proposals in Nevada, Maine and California would authorize recreational marijuana use, while Floridians will vote on whether to allow medical marijuana use.
Legalization of marijuana in the United States has spread rapidly over the last few years. Half of the states have already legalized marijuana in some form. Alaska, Colorado, Oregon, Washington and the District of Columbia have legalized it for recreational use. And the Democratic Party platform committee recently voted 81 to 80 to amend the federal Controlled Substances Act to remove marijuana from the list of Schedule 1 drugs. The stated purpose of this proposed amendment is to “provid[e] a reasoned pathway for future legalization.”
States with some form of legalized marijuana have implemented stringent regulatory and licensing schemes with regard to the who, what, where and how of marijuana possession, cultivation, and distribution. But policymakers have failed to address an important area: the marijuana industry’s energy and climate impacts. Although marijuana is a plant, it is not a “green” product when grown indoors. As more states – and, potentially, Congress – consider legalizing the marijuana industry, they should also adopt rules to make it more environmentally sustainable.
Indoor marijuana farms are energy hogs
Indoor marijuana cultivation is one of the most energy-intensive industries in the United States, generating nearly US$6 billion in energy costs annually. According to the Northwest Power and Conservation Council, which carries out energy planning for the Columbia River Basin states (Montana, Idaho, Washington and Oregon), growing marijuana indoors consumes up to 5,000 kilowatt-hours of electricity per kilogram of output. For comparison, aluminum production requires about 16 kilowatt-hours per kilogram.
Colorado’s experience demonstrates marijuana’s large energy footprint. Since the state legalized recreational marijuana in 2014, the industry has expanded rapidly there. In 2015 legal marijuana businesses in Colorado made nearly $1 billion in sales, up 42 percent from the previous year. And as marijuana businesses become more competitive and specialized, growers are moving their farms indoors to get a more controlled product.
Indoor cultivation requires electricity to power high-intensity lights, frequent air exchanges and ventilation, and to maintain consistent temperatures and humidity levels day and night. As a result, the state now has numerous indoor warehouses that consume huge quantities of electricity.
Experts estimate that a 5,000-square-foot indoor marijuana facility in Colorado consumes six times more electricity per square foot than an average commercial business, and 49 times more than an average residence. Last year Denver officials sought guidance from the Department of Energy on ways to curb the industry’s power requirements. Electricity use in Denver is rising by 1.2 percent yearly, and marijuana farms account for nearly half of the increase.
Colorado has set a goal of generating 30 percent of its electricity from renewable sources by 2020. Currently, however, only 18 percent of its electricity comes from renewable sources. The rest is generated from coal and natural gas.
On-site generation systems, such as rooftop solar arrays, and community-scale energy projects cannot produce enough electricity to meet marijuana growers’ energy needs. As a result, the marijuana industry is indirectly increasing Colorado’s reliance on fossil fuel.
Legalization provides some energy benefits. For example, it allows indoor cultivators to connect to existing electricity grids instead of relying on carbon-intensive gasoline and diesel generators. However, these benefits are swamped by the industry’s fast-growing electricity requirements.
Experts estimate that nationwide, indoor marijuana cultivation accounts for nearly 15 million metric tons of carbon emissions annually – more than the annual energy-related emissions of South Dakota, Delaware, Rhode Island and Vermont, or the District of Columbia. Public utility commissioners across the nation are discussing strategies for managing power demand from indoor pot growers.
Legalize and regulate
When states legalize marijuana cultivation, they establish detailed regulatory and licensing schemes governing who may sell, possess and cultivate the plant, where they may do so, and how much they must pay for licenses. Policymakers should also seize this opportunity to enact rules governing the industry’s climate and energy impacts.
Since indoor growers consume such enormous amounts of electricity, policymakers should start by requiring indoor cultivators to consume only carbon-free energy sources or to pay a carbon fee until such measures can be implemented.
Boulder, Colorado is addressing this issue by implementing city and county licensing schemes that require indoor marijuana cultivators to use energy monitoring technology and routinely report their energy use. Growers must offset their energy use by utilizing 100 percent renewable energy, purchasing renewable energy credits, or paying a carbon fee. However, few other states or localities have followed Boulder’s lead.
Oregon has established a task force to study energy and water use for marijuana production. The group is scheduled to report its findings to the state legislature later this summer. Preliminary indications are that the task force will call on growers to follow energy best practices, but it is unclear whether it will recommend making this policy mandatory or merely a suggestion.
States that do not have enough renewable energy generation to meet the industry’s electricity demands, such as in Colorado, should take a two-pronged approach. First, they should require indoor growers to pay escalating carbon fees based on their electricity consumption. These funds should be used to support development of more efficient technology and climate-friendly electricity facilities.
Second, legislators should also require an exponential increase in the percentage of energy consumed by indoor growers from renewable energy sources via on site generation – such as rooftop solar – or community renewable energy facilities. This two-pronged approach would ensure growers do not become complacent just paying the fee.
The best time to address impacts of this magnitude is before they occur, not after a major industry is already established. Marijuana production is rapidly developing into an extremely lucrative industry that can afford to manage its impacts on the environment.
Why do people sext? Why do they send racy or naked photos or videos and sexually loaded texts?
For a short-term hookup, sexting might seem like a direct way to get what you want – or at least try to. But according to my research, sexting is actually most likely to occur within a committed relationship. Some research suggests that people often engage in sexting after being coerced by romantic partners or to avoid an argument with their romantic partner. So perhaps anxiety and concern about what your romantic partner thinks about you promote behaviors like sexting.
As a human development researcher who studies how technology influences relationships, I wanted to understand if people who are anxious about dating or about what their partner thinks of them are more likely to sext.
So where does this relationship anxiety come from?
One of the major theories regarding relationships is called attachment theory. It suggests that the way you related to your caregiver as an infant (and vice versa) shapes how you come to view relationships later in life.
If your caregiver was attuned to your needs and responsive, you will develop a secure attachment. That means you are comfortable with close relationships because your experience paid off – Mom or Dad was there when you were distressed or hungry or cold. From that experience, you learned that relationships are safe and reciprocal, and your attachment anxiety is low.
But if your caregiver was not so attuned to your needs, was intrusive or inattentive, you might develop what is called an insecure attachment. If something you wanted emotionally or physically (like comfort) went unfulfilled, you might end up anxious about relationships as an adult. You might realize that relationships may not be trustworthy, not invest in close relationships, and avoid intimacy all together.
Do people sext because of relational anxiety?
My colleagues, Michelle Drouin and Rakel Delevi, and I hypothesized that people who were afraid of being single or had dating anxiety and who were, at the same time, anxious or insecure in their attachment style would be more likely to sext. We also thought these singles would be more likely to sext their romantic partners, even when their relationship wasn’t very committed.
We gave 459 unmarried, heterosexual, undergraduate students an online questionnaire to learn more about how relational anxiety influences sexting behavior. It covered questions measuring their sexting behaviors, relationship commitment needed to engage in sexting, their fear of being single, their dating anxiety and their attachment style (secure or insecure). Half of the people who took the survey were single, and about 71 percent were female.
We found that people in romantic relationships – whether of long or short duration – were more likely to have sexted than those who did not have romantic partners. There were no gender differences for engaging in sexting, except that males were more likely than females to have sent a text propositioning sexual activity.
We also found that, generally, dating anxiety from fear of negative evaluation from the romantic partner (basically, worrying about what your partner thinks of you) and having a more secure attachment style (i.e., comfort with intimacy and close relationships) predicted if someone had sent a sexually suggestive photo or video, a picture in underwear or lingerie, a nude photo or a sexually suggestive text.
We expected to find that anxiety would prompt people to sext but were surprised that comfort with intimacy related to sexting behaviors. We also expected to find that sexting would occur in relationships without a lot of commitment, meaning that we thought that sexting would be part of the wooing.
But it turns out that people who are comfortable with close relationships (a secure attachment style) and also worry about what their partner might think of them are more likely to engage in sexting, but only if there some level of commitment in the relationship.
So our hypothesis was only partially confirmed.
What’s dating anxiety got to do with it?
What this tells us is that people may be concerned with pleasing their partner’s desire – or perceived desire – to engage in sexting and that it is the comfort with intimacy in relationships that may allow sexting to occur. And, when there is greater relationship commitment, this continues to be the case.
It appears that there is less stigma and greater comfort with sexting, provided that one perceives that his or her partner wants to sext and if there is a degree of relationship commitment.
So, a little sexting within a relationship might not be too bad.
In 2008, short of sending a suitcase full of cash, there was essentially just one way for an individual to send money between, say, the United States and Europe. You had to wire the money through a mainstream financial service, like Western Union or a bank. That meant paying high fees and waiting up to several days for the money to arrive.
A radically new option arose in 2009 with the introduction of bitcoin. Bitcoin makes it possible to transfer value between two individuals anywhere in the world quickly and at minimal cost. It is often called a “cryptocurrency,” as it is purely digital and uses cryptography to protect against counterfeiting. The software that executes this cryptography runs simultaneously on computers around the world. Even if one or more of these computers is misused in an attempt to corrupt the bitcoin network (such as to steal money), the collective action of the others ensures the integrity of the system as a whole. Its distributed nature also enables bitcoin to process transactions without the fees, antiquated networks and (for better or worse) the rules governing intermediaries like banks and wire services.
Bitcoin’s exciting history and social impact have fired imaginations. The aggregate market value of all issued bitcoins today is roughly US$10 billion. The computing devices that maintain its blockchain are geographically dispersed and owned by thousands of different individuals, so the bitcoin network has no single owner or point of control. Even its creator remains a mystery (despite manyefforts tounmask her, him or them). Bitcoin’s lack of government regulation made it attractive to black markets and malware writers. Although the core system is well-secured, people who own bitcoins have experienced a litany of heists and fraud.
Even more than the currency itself, though, what has drawn the world’s attention are the unprecedented reliability and security of bitcoin’s underlying transaction system, called a blockchain. Researchers, entrepreneurs, and developers believe that blockchains will solve a stunning array of problems, such as stabilization of financial systems, identification of stateless persons, establishing title to real estate and media, and efficiently managing supply chains.
Understanding the blockchain
Despite its richly varied applications, a blockchain such as bitcoin’s aims to realize a simple goal. Abstractly, it can be viewed as creating a kind of public bulletin board, often called a “distributed ledger.” This ledger is public. Anyone – plebeian or plutocrat, baker or banker – can read it. And anyone can write valid data to it. Specifically, in bitcoin, any owner of money can add a transaction to the ledger that transfers some of her money to someone else. The bitcoin network makes sure that the ledger includes only authorized transactions, meaning those digitally signed by the owners of the money being transferred.
The key feature of blockchains is that new data may be written at any time, but can never be changed or erased. At first glance, this etched-in-stone rule seems a needless design restriction. But it gives rise to a permanent, ever-growing transactional history that creates strong transparency and accountability. For example, the bitcoin blockchain contains a record of every transaction in the system since its birth. This feature makes it possible to prevent account holders from reneging on transactions, even if their identities remain anonymous. Once in the ledger, a transaction is undeniable. The indelible nature of the ledger is much more powerful and general, though, allowing blockchains to support applications well beyond bitcoin.
Consider, for example, the management of title to a piece of land or property. Property registries in many parts of the world today are fragmented, incomplete, poorly maintained, and difficult to access. The legal uncertainty surrounding ownership of property is a major impediment to growth in developing economies. Were property titles authoritatively and publicly recorded on a blockchain, anyone could learn instantly who has title to a piece of property. Even legitimate anonymous ownership – as through a private trust – could be recorded on a blockchain.
Such transparency would help resolve legal ambiguity and shed light on malfeasance. Advocates envision similar benefits in blockchain recording of media rights – such as rights to use images or music – identity documents and shipping manifests. In addition, the decentralized nature of the database provides resilience not just to technical failures, but also to political ones – failed states, corruption and graft.
Blockchains can be enhanced to support not just transactions, but also pieces of code known as smart contracts. A smart contract is a program that controls assets on the blockchain – anything from cryptocurrency to media rights – in ways that guarantee predictable behavior. A smart contract may be viewed as playing the role of a trusted third party: Whatever task it is programmed to do, it will carry out faithfully.
Suppose for example that a user wishes to auction off a piece of land for which her rights are represented on a blockchain. She could hire an auctioneer, or use an online auction site. But that would require her and her potential customers to trust, without proof, that the auctioneer conducts the auction honestly.
To achieve greater transparency, the user could instead create a smart contract that executes the auction automatically. She would program the smart contract with the ability to deliver the item to be sold and with rules about minimum bids and bidding deadlines. She would also specify what the smart contract is to do at the end of the auction: send the winning bid amount from the winner to the seller’s account and transfer the land title to the winner.
Because the blockchain is publicly visible, anyone with suitable expertise could check that the code in the smart contract implements a fair and valid auction. Auction participants would only need to trust the correctness of the code. They wouldn’t need to rely on an auctioneer to run the auction honestly – and as an added benefit, they also wouldn’t need to pay high auctioneer fees.
Behind this compelling vision lurk many technical challenges. The transparency and accountability of a fully public ledger have many benefits, but are at odds with confidentiality. Suppose the seller mentioned above wanted to conduct a sealed-bid auction or conceal the winning bid amount? How could she do this on a blockchain that everyone can read? Achieving both transparency and confidentiality on blockchains is in fact possible, but requires new techniquesunder development by researchers.
Another challenge is ensuring that smart contracts correctly reflect user intent. A lawyer, arbiter or court can remedy defects or address unforeseen circumstances in written contracts. Smart contracts, though, are expressly designed as unalterable code. This inflexibility avoids ambiguity and cheating and ensures trustworthy execution, but it can also cause brittleness. An excellent example was the recent theft of around $55 million in cryptocurrency from a smart contract. The thief exploited a software bug, and the smart contract creators couldn’t fix it once the contract was running.
Bitcoin is a proof of concept of the viability of blockchains. As researchers and developers overcome the technical challenges of smart contracts and other blockchain innovations, marveling at money flying across the Atlantic will someday seem quaint.
Ari Juels, Professor of Computer Science, Jacobs Technion-Cornell Institute, Cornell Tech, and Co-Director, Initiative for CryptoCurrencies and Contracts (IC3), Cornell University and Ittay Eyal, Research Associate, Computer Science and Associate Director, Initiative For Cryptocurrencies and Contracts (IC3), Cornell University
There is some evidence that more restrictions can reduce gun violence, but another recent shooting highlighted some limitations of regulation. British Member of Parliament Jo Cox was murdered with a “makeshift gun” despite the United Kingdom’s restrictive gun-control laws.
The threat of self-manufactured firearms is not new, but a critical barrier is collapsing. Until recently, most people didn’t have the skills to make a weapon as capable as commercially available ones. However, recent developments in the field of additive manufacturing, also known as 3D printing, have made home manufacturing simpler than ever before. The prospect of more stringent legislation is also fueling interest in at-home production.
Those of us in the research community have also been addressing the security implications of additive manufacturing. A 2014 conference of intelligence community and private sector professionals noted that current at-home and small-scale 3D printing technology can’t produce the same quality output as industrial equipment, and doesn’t work with as wide a range of plastics, metals and other materials. Nevertheless, participants recommended a number of policies, such as more rigorous intellectual property laws, to counter the evolving threat of unregulated 3D-printed weapons. These types of policies will become increasingly important as at-home manufacturing of firearms weakens traditional gun control regulations such as those focusing on the buying and selling of weapons.
Beyond regulating the hardware, governments and industry professionals can also work to more effectively secure the files needed to build components for weapons of mass destruction. Arms control analyst Amy Nelson points out that the risk this kind of data will spread increases as it becomes increasingly digital.
Terrorist groups and other nongovernment forces could also find ways to use 3D printing to make more destructive weapons. We argue that despite these groups’ interest in using weapons of mass destruction, they don’t use them regularly because their homemade devices are inherently unreliable. Additive manufacturing could help these groups produce more effective canisters or other delivery mechanisms, or improve the potency of their chemical and biological ingredients. Such developments would make these weapons more attractive and increase the likelihood of their use in a terror attack.
Where to go from here
The worst threats 3D printing poses to human life and safety are likely some distance in the future. However, the harder policymakers and others work to restrict access to handguns or unconventional weapons, the more attractive 3D printing becomes to those who want to do harm.
Additive manufacturing holds great promise for improvements across many different areas of people’s lives. Scholars and policymakers must work together to ensure we can take advantage of these benefits while guarding against the technology’s inherent dangers.
Imagine a future spacecraft following New Horizons’ trailblazing path to Pluto, but instead of flying past its target, the next visitor touches down in the midst of tall mountains on the icy plains of Pluto’s heart.
There’s no need to wait for that fantasy trip, thanks to new video produced by New Horizons scientists. Made from more than 100 New Horizons images taken over six weeks of approach and close flyby, the video offers a “trip” to Pluto. It starts with a distant spacecraft’s view of Pluto and its largest moon, Charon – closing the distance day by day – with a dramatic “landing” on the shoreline of Pluto’s frozen plains.
“Just over a year ago, Pluto was just a dot in the distance,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute, Boulder, Colorado. “This video shows what it would be like to ride aboard an approaching spacecraft and see Pluto grow to become a world, and then to swoop down over its spectacular terrains as if we were approaching some future landing.”
The most efficient-walking humanoid ever created wears size-13 sneakers, report its creators.
While most machines these days hunch at the waist and plod along on flat feet, DURUS strolls like a person. Its legs and chest are elongated and upright. It lands on the heel of its foot, rolls through the step, and pushes off its toe. And it wears shoes as it walks under its own power on a treadmill in the AMBER Lab at the Georgia Institute of Technology.
“Our robot is able to take much longer, faster steps than its flat-footed counterparts because it’s replicating human locomotion,” says Aaron Ames, director of the lab and a professor in the George W. Woodruff School of Mechanical Engineering and School of Electrical and Computer Engineering.
“Multi-contact foot behavior also allows it to be more dynamic, pushing us closer to our goal of allowing the robot to walk outside in the real world.”
As Ames tells it, the traditional approach to creating a robotic walker is similar to an upside-down pendulum. Researchers typically use comparatively simple algorithms to move the top of the machine forward while keeping its feet flat and grounded. As it shuffles along, the waist stays at a constant height, creating the distinctive hunched look. This not only prevents these robots from moving with the dynamic grace present in human walking, but also prevents them from efficiently propelling themselves forward.
The Georgia Tech humanoid walked with flat feet until about a week ago, although it was powered by fundamentally different algorithms than most robots.
To demonstrate the power of those methods, Ames and his team of student researchers built a pair of metal feet with arched soles. They applied their complex mathematical formulas, but watched DURUS misstep and fall for three days. The team continued to tweak the algorithms and, on the fourth day, the robot got it.
The machine walked dynamically on its new feet, displaying the heel-strike and toe push-off that is a key feature of human walking. The robot is further equipped with springs between its ankles and feet, similar to elastic tendons in people, allowing for a walking gait that stores mechanical energy from a heel strike to be later reclaimed as the foot lifts off the ground.
This natural gait makes DURUS very efficient. Robot locomotion efficiency is universally measured by a “cost of transport,” or the amount of power it uses divided by the machine’s weight and walking speed. Ames says the best humanoids are approximately 3.0. Georgia Tech’s cost of transport is 1.4, all while being self-powered—it’s not tethered by a power cord from an external source.
This new level of efficiency is achieved in no small part through human-like foot behavior. DURUS had earned its new pair of shoes.
“Flat-footed robots demonstrated that walking was possible,” says Ames, “but they’re a starting point, like a propeller-powered airplane. It gets the job done, but it’s not a jet engine. We want to build something better, something that can walk up and down stairs or run across a field.”
He adds these advances have the potential to usher in the next generation of robotic assistive devices like prostheses and exoskeletons that can enable the mobility-impaired to walk with ease.
Graduate student Jake Reher led the student team. Graduate student, Eric Ambrose created the shoes. The robotics division of SRI International collaborated on the DURUS design.