New techniques for building microelectromechanical microsystems show promise.
External row of seven emitters that are part of a 49-emitter array. The scalloping on the exterior of the emitters, due to the layer-by-layer manufacturing, is visible. Image: Anthony Taylor and Luis F Velásquez-García (edited by MIT News)
Scientia — Microelectromechanical systems — or MEMS — were a $12 billion business in 2014. But that market is dominated by just a handful of microsystems devices, such as the accelerometers that reorient the screens of most smartphones.
That’s because manufacturing MEMS has traditionally required sophisticated semiconductor fabrication facilities, which cost tens of millions of dollars to build. Potentially useful MEMS have languished in development because they don’t have markets large enough to justify the initial capital investment in production.
Two recent papers from researchers at MIT’s Microsystems Technologies Laboratories offer hope that that might change. In one, the researchers show that a MEMS-based gas sensor manufactured with a desktop device performs at least as well as commercial sensors built at conventional production facilities.
In the other paper, they show that the central component of the desktop fabrication device can itself be built with a 3-D printer. Together, the papers suggest that a widely used type of MEMS gas sensor could be produced at one-hundredth the cost with no loss of quality.
A completed chip with a wired graphene oxide gas sensor. The graphene oxide film is the greenish dot covering the electrode structure. Image: Anthony Taylor and Luis F Velásquez-García
The researchers’ fabrication device sidesteps many of the requirements that make conventional MEMS manufacture expensive. “The additive manufacturing we’re doing is based on low temperature and no vacuum,” says Luis Fernando Velásquez-García, a principal research scientist in MIT’s Microsystems Technology Laboratories and senior author on both papers. “The highest temperature we’ve used is probably 60 degrees Celsius. In a chip, you probably need to grow oxide, which grows at around 1,000 degrees Celsius. And in many cases the reactors require these high vacuums to prevent contamination. We also make the devices very quickly. The devices we reported are made in a matter of hours from beginning to end.”
Welcome resistance
For years, Velásquez-García has been researching manufacturing techniques that involve dense arrays of emitters that eject microscopic streams of fluid when subjected to strong electric fields. For the gas sensors, Velásquez-García and Anthony Taylor, a visiting researcher from the British company Edwards Vacuum, use so-called “internally fed emitters.” These are emitters with cylindrical bores that allow fluid to pass through them.
In this case, the fluid contained tiny flakes of graphene oxide. Discovered in 2004, graphene is an atom-thick form of carbon with remarkable electrical properties. Velásquez-García and Taylor used their emitters to spray the fluid in a prescribed pattern on a silicon substrate. The fluid quickly evaporated, leaving a coating of graphene oxide flakes only a few tens of nanometers thick.
The flakes are so thin that interaction with gas molecules changes their resistance in a measurable way, making them useful for sensing. “We ran the gas sensors head to head with a commercial product that cost hundreds of dollars,” Velásquez-García says. “What we showed is that they are as precise, and they are faster. We make at a very low cost — probably cents — something that works as well as or better than the commercial counterparts.”
To produce those sensors, Velásquez-García and Taylor used electrospray emitters that had been built using conventional processes. However, in the December issue of the Journal of Microelectromechanical Systems, Velásquez-García reports using an affordable, high-quality 3-D printer to produce plastic electrospray emitters whose size and performance match those of the emitters that yielded the gas sensors.
Made to order
In addition to making electrospray devices more cost-effective, Velásquez-García says, 3-D printing also makes it easier to customize them for particular applications. “When we started designing them, we didn’t know anything,” Velásquez-García says. “But at the end of the week, we had maybe 15 generations of devices, where each design worked better than the previous versions.”
Indeed, Velásquez-García says, the advantages of electrospray are not so much in enabling existing MEMS devices to be made more cheaply as in enabling wholly new devices. Besides making small-market MEMS products cost-effective, electrospray could enable products incompatible with existing manufacturing techniques.
Optical micrograph of a fabricated conductometric graphene oxide gas sensor. The inset (top left corner) shows a close-up view of the active area of the sensor. Image: Anthony Taylor and Luis F Velásquez-García
“In some cases, MEMS manufacturers have to compromise between what they intended to make, based on the models, and what you can make based on the microfabrication techniques,” Velásquez-García says. “Only a few devices that fit into the description of having large markets and not having subpar performance are the ones that have made it.”
Electrospray could also lead to novel biological sensors, Velásquez-García says. “It allows us to deposit materials that would not be compatible with high-temperature semiconductor manufacturing, like biological molecules,” he says.
“For sure, the paper opens new technical paths to making gas microsensors,” says Jan Dziuban, head of the Division of Microengineering at Wroclaw University of Technology in Poland. “From a technical point of view, the process may be easily adapted to mass fabrication.”
“But promising results must be proved statistically,” he cautions. “Personal experience tells me that plenty of very promising materials for new sensors, utilizing nanostructured materials, which have been published in high-level scientific papers, haven’t resulted in reliable products.”
China launch dark matter detecting satellite into orbit
China has successfully placed a satellite called the Dark Matter Particle Explorer (DAMPE) into a sun-synchronous orbit around the Earth. Its mission is to study high-energy particles and γ-rays as part of an overall objective to learn more about dark matter. The satellite was boosted into the sky by a Chinese Long March 2D rocket, launched from a northwest province in China.
The satellite, nicknamed “Wukong” (Monkey King) by the Chinese public is part of a collaborative effort between China’s Academy of Sciences, several academic institutions in Italy, and the University of Geneva—its launch marks a major advance for the country into the study of space science, from space.
The satellite has four sensors onboard: a BGO calorimeter, a silicon-Tungsten Tracker a neutron detector and a plastic scintillator detector. Each is part of the overall goal to capture high energy particles and then to trace them back to their origin, which the team believes would be dark matter particle collisions.
The sensors have been designed to detect photons and electrons with a higher resolution than can be found by testers residing in underground sensor facilities or the AMS aboard the International Space Station. Tracking dark matter back to its source, the team believes, should shed some light on dark matter itself, which continues to defy observation despite many efforts across the globe.
One focused mission by the team working with data from DAMPE will be to see if the new satellite can be used to reveal the source of signals seen by AMS, such as if they are caused by pulsars or dark matter collisions.
The DAMPE mission is the first of five space science missions the Chinese have developed—two more will take place next year–one of which is being billed as the first quantum-communications satellite (its purpose is to see if photons sent from ground stations to the satellite can continue to be entangled with their Earthbound counterparts, which, if so, could eventually lead to a quantum network.
The other mission will have the Chinese sending an X-ray telescope into orbit with unique energy band sensing capabilities—it will be used mostly to study radiation emitted from black holes. Director of the National Space Science Center, Wu Ji, told the press that the country is embarking on the new space science missions to seek further progress in the field.
Microsoft is focusing on developers, not the general public, for the latest in HoloLens events and announcements. The good news for the public is that, in doing so, the conversation is shedding light on what is behind HoloLens and what to expect once availability happens.
Do not expect to be mentally transported into another world; you remain in a familiar place where virtual characters may join your space. You’re looking at sessions of mixed reality, not virtual reality.
Engadget features editor Joseph Volpe asserted that “any and all comparisons to emerging virtual reality tech and related gaming or entertainment applications should be excised from the conversation for now. It’s not ‘immersive’ as one Microsoft rep stressed to me, clearly keen to avoid the confused commingling of AR and VR buzzwords. It’s ‘complementary."”
The development edition will ship in the first quarter of 2016, for $3000.
This is an augmented reality headset; some watchers call it an “untethered wearable.” HoloLens works all on its own: all the hardware necessary to run any program is inside the headset, said Popular Science. Microsoft’s definition of its HoloLens: The first holographic computer running Windows 10. You get to place holograms in your own physical environment.
From mixed reality to virtual reality, though, the immediate perception of a headset development on the horizon is gaming. Nonetheless, the HoloLens creators point out that it has been engineered for productivity as well as design.
“HoloLens is very much a powerful tool for business, science and education—both Volvo and NASA’s Jet Propulsion Laboratory are actively experimenting with it,” said Engadget’s Volpe.
Developers can check out HoloLens at the Microsoft store on 5th Avenue in New York City where showcasing has begun.
For Bryan Lukfkin in Gizmodo, a key role the user’s eyes will play was noteworthy. “With the HoloLens, the ‘cursor’ is your eyes. You look around a real room you’re in and select holographic images that appear in your goggles by hovering the cursor in the middle of your field of vision over the object.
To interact with the object, you ‘air tap.’ In front of the goggles by pointing your index finger in the air and making a fast swipe down motion. Voice commands are also at your disposal.”
Edward Baig of USA Today shared the experience: At the store, Baig found himself shooting at robotic aliens firing at him as he fired back at them, floating around him. They seemed to hide inside the walls of the room and he went after them. He could see them through a built-in X-ray feature.
Those were games; Lufkin described a demo which indicated how businesses and other organizations may use HoloLens for presentations.
Goodbye yawnfests of having to watch 23 charts on a white screen.
“The idea here is that you can replace boring PowerPoints with holograms. (How appropriate for Microsoft!) In the demo, I stepped into a fictional boardroom pitch for a luxury watch. I looked at real table in the room and saw a large hologram watch blown up to the size of a golden retriever.
I could move the cursor with my eyes to different points of interest on the watch. When I looked at the band, a pop up told me what the links were made of. In another spot I was given info about the battery.”
“What I can tell you is that the technology is ‘mindblowing,’ said Baig. He said that “when digital becomes part of the physical and vice versa, the most promising reality is that you’re in for a treat.”
Said Michael Nuñez in Popular Science: “It’s true that the HoloLens already has all of necessary computing power to be used as a legitimate productivity tool. Now all it needs is a killer app.”
He said the HoloLens is powered by a CPU, graphics process unit (GPU), and something that Microsoft is calling a “holographic processing unit” (HPU), which interprets and processes data from the device’s sensor array.
Black holes could grow as large as 50 billion suns before their food crumbles into stars according to research
This artist’s concept depicts a supermassive black hole at the center of a galaxy. The blue color here represents radiation pouring out from material very close to the black hole. The grayish structure surrounding the black hole, called a torus, is made up of gas and dust. Credit: NASA/JPL-Caltech
Scientia — Black holes at the heart of galaxies could swell to 50 billion times the mass of the sun before losing the discs of gas they rely on to sustain themselves, according to research at the University of Leicester.
In a study titled ‘How Big Can a Black Hole Grow?’, Professor Andrew King from the University of Leicester’s Department of Physics and Astronomy explores supermassive black holes at the centre of galaxies, around which are regions of space where gas settles into an orbiting disc.
This gas can lose energy and fall inwards, feeding the black hole. But these discs are known to be unstable and prone to crumbling into stars.
Professor King calculated how big a black hole would have to be for its outer edge to keep a disc from forming, coming up with the figure of 50 billion solar masses.
The study suggests that without a disc, the black hole would stop growing, meaning 50 billion suns would roughly be the upper limit. The only way it could get larger is if a star happened to fall straight in or another black hole merged with it.
Professor King said: “The significance of this discovery is that astronomers have found black holes of almost the maximum mass, by observing the huge amount of radiation given off by the gas disc as it falls in. The mass limit means that this procedure should not turn up any masses much bigger than those we know, because there would not be a luminous disc.
“Bigger black hole masses are in principle possible—for example, a hole near the maximum mass could merge with another black hole, and the result would be bigger still. But no light would be produced in this merger, and the bigger merged black hole could not have a disc of gas that would make light.
“One might nevertheless detect it in other ways, for example as it bent light rays passing very close to it (gravitational lensing) or perhaps in future from the gravitational waves that Einstein’s General Theory of Relativity predicts would be emitted as it merged.”
– Credit and Resource –
More information: How Big Can a Black Hole Grow? arXiv:1511.08502 [astro-ph.GA] arxiv.org/abs/1511.08502
Interest is growing in brain stimulation devices (tDCS) — and regulating them may prove tricky.
People building their own devices for transcranial direct current stimulation (tDCS) have often invested substantial time looking at academic research on the subject. “They do look to scientific papers and in a lot of ways they do follow scientific precedent,” PhD student Anna Wexler says. “In other ways, they do their own thing.”
Scientia — It may sound unusual, but it’s true: In recent years a growing number of people have been hooking their heads up to electrodes, in an attempt to stimulate their brains using a direct electrical current. Some of them do this via homemade devices; others may be using a new direct-to-consumer kit that just hit the market.
But why, exactly, are people doing such a thing at all? And to what extent should this practice — seen only in research labs until a few years ago — be regulated?
The first question is easier to answer than the second, according to Anna Wexler, a PhD student in MIT’s Program in Science, Technology, and Society, who had two new papers on the subject appear in academic journals this fall. Following lab research that started appearing 15 years ago, some people believe they can give themselves a kind of neurological tuneup through electrical stimulation, producing better-functioning brains.
“The common thread in all these people is that they’re interested in self-improvement,” Wexler says. “They’re in two camps. Some are interested in enhancing cognition, learning faster, performing better at memory tasks. And another group is interested in self-treating a variety of mood disorders.”
As Wexler discusses in one paper, appearing recently in the Journal of Medical Ethics, the people building their own devices for transcranial direct current stimulation (tDCS) have often invested substantial time looking at academic research on the subject, some of which suggests positive outcomes from brain stimulation. Their ranks are being joined by more casual consumers who can now purchase inexpensive devices to do the same thing.
Such products have produced a regulatory debate among academic researchers. The U.S. Food and Drug Administration (FDA) has not approved tDCS as a treatment for any malady. On the other hand, if such tools are marketed as helping generalized “wellness,” not as a cure for one problem, they may fall outside the FDA’s purview.
“There are a lot of blurry lines in food, drug, and cosmetic regulation,” observes Wexler, who presents the most comprehensive research overview yet written on the nuances of the regulation issue, appearing this fall in an article for the Journal of Law and Biosciences. “The definition of a medical device is not based on a definition of its action, but on how the device is intended to be used. And the FDA has historically judged intended use by manufacturers’ marketing claims.”
Wexler was also one of the experts asked to speak at an FDA panel held on the topic in November.
Gaining currency
Academic interest in tDCS gained currency after a 2000 paper by two German neurophysiologists showed that passing a weak electrical current through the motor cortex helped people perform motor tasks better. The volume of studies increased slowly for several years — about 100 in all through 2007 — but has shot up recently: There have been over 100 published studies in each of the last four years, with about 300 being published in 2014 alone. Several companies produce tDCS machines used in lab settings where such research takes place.
Researchers have not really reached a firm consensus on the effects of tDCS, however. As Wexler notes, “no serious adverse effects” have been found among 10,000 human subjects in academic research, but one study, published in the Journal of Neuroscience last year, found that tDCS appeared to impair cognitive function in at least some individuals. Still on the other hand, numerous studies do show some kind of functional cognitive enhancement due to tDCS.
Wexler’s original research on the do-it-yourselfers — what she terms the “DIY tDCS crowd” — in the Journal of Medical Ethics provides an initial demographic look at who they are. Wexler conducted interviews, and examined online videos, blog posts, and forums, and found that most of the people involved are male; come from one of three dozen countries; and include “at least a handful” of lab researchers.
“They do look to scientific papers and in a lot of ways they do follow scientific precedent,” Wexler says. “In other ways, they do their own thing.” For instance, because “there is no agreement on what level of tDCS is bad for you,” she adds, the DIY tDCS community reports a wide variety of usage patterns, from relatively light to heavy amounts of stimulation.
Other scholars say Wexler’s work is original and significant. Her research into the DIY tDCS community is the “best encapsulation of the near-history of this phenomenon, which has really arisen in the last four to five years,” says Peter Reiner, a professor of psychiatry and expert in neuroethics at the University of British Columbia, who has also studied the issue. Reiner adds that Wexler’s “scholarship is excellent,” and observes that it is unusual for a graduate student to be looked to as a voice for policymakers.
The path ahead
In lieu of a complete scientific consensus on the effects of tDCS, however, it is not yet clear who should regulate the devices, let alone in what ways.
As Wexler puts it in the Journal of Law and Biosciences paper, there is not a “regulatory gap” pertaining to brain stimulation, but rather, “there are multiple, distinct pathways by which consumer tDCS devices can be regulated in the United States.” For example, they could be regulated not by the FDA but as regular consumer devices, subject to consumer safety and advertising laws under federal agencies like the Consumer product Safety Commission and the Federal Trade Commission.
Whatever path lies ahead, Wexler suggests regulators should follow an “open engagement” model of reaching out to the community of tDCS users to get a sense of the extent of use and the degree to which new guidelines are needed.
“I think the open engagement approach is just more practical,” Wexler says. “You can’t crack down on people building the devices. If anybody wants to go out and buy a battery and wires, it’s their right to do so.”
On the other hand, engagement with users, and perhaps a third-party review of tDCS effects by a group such as the National Academy of Medicine, would encourage at-home tDCS users to follow regulatory prescriptions rather than going their own way.
“We’ll have to wait and see,” Wexler says of the regulatory debate’s outcome. “But the DIY community really looks to scientific papers for guidance. They do value what scientists say.”
Computer system passes visual Turing test and leads to character-drawing machines fool human judges.
Scientia — Researchers at MIT, New York University, and the University of Toronto have developed a computer system whose ability to produce a variation of a character in an unfamiliar writing system, on the first try, is indistinguishable from that of humans.
Humans and machines were given an image of a novel character (top) and asked to produce new versions. A machine generated the nine-character grid on the left. Image: Jose-Luis Olivares/MIT (figures courtesy of the researchers)
That means that the system in some sense discerns what’s essential to the character — its general structure — but also what’s inessential — the minor variations characteristic of any one instance of it.
As such, the researchers argue, their system captures something of the elasticity of human concepts, which often have fuzzy boundaries but still seem to delimit coherent categories. It also mimics the human ability to learn new concepts from few examples. It thus offers hope, they say, that the type of computational structure it’s built on, called a probabilistic program, could help model human acquisition of more sophisticated concepts as well.
“In the current AI landscape, there’s been a lot of focus on classifying patterns,” says Josh Tenenbaum, a professor in the Department of Brain and Cognitive sciences at MIT, a principal investigator in the MIT Center for Brains, Minds and Machines, and one of the new system’s co-developers. “But what’s been lost is that intelligence isn’t just about classifying or recognizing; it’s about thinking.”
“This is partly why, even though we’re studying hand-written characters, we’re not shy about using a word like ‘concept,’” he adds. “Because there are a bunch of things that we do with even much richer, more complex concepts that we can do with these characters. We can understand what they’re built out of. We can understand the parts. We can understand how to use them in different ways, how to make new ones.”
The new system was the thesis work of Brenden Lake, who earned his PhD in cognitive science from MIT last year as a member of Tenenbaum’s group, and who won the Glushko Prize for outstanding dissertations from the Cognitive Science Society. Lake, who is now a postdoc at New York University, is first author on a paper describing the work in the latest issue of the journal Science. He’s joined by Tenenbaum and Ruslan Salakhutdinov, an assistant professor of computer science at the University of Toronto who was a postdoc in Tenenbaum’s group from 2009 to 2011.
Which nine-character grid in each pair was generated by a machine? Answers by row: 1,2;2,1;1,1. Courtesy of the researchers
Rough ideas
“We analyzed these three core principles throughout the paper,” Lake says. “The first we called compositionality, which is the idea that representations are built up from simpler primitives. Another is causality, which is that the model represents the abstract causal structure of how characters are generated. And the last one was learning to learn, this idea that knowledge of previous concepts can help support the learning of new concepts. Those ideas are relatively general. They can apply to characters, but they could apply to many other types of concepts.”
The researchers subjected their system to a battery of tests. In one, they presented it with a single example of a character in a writing system it had never seen before and asked it to produce new instances of the same character — not identical copies, but nine different variations on the same character. In another test, they presented it with several characters in an unfamiliar writing system and asked it to produce new characters that were in some way similar. And in a final test, they asked it to make up entirely new characters in a hypothetical writing system.
Human subjects were then asked to perform the same three tasks. Finally, a separate group of human judges was asked to distinguish the human subjects’ work from the machine’s. Across all three tasks, the judges could identify the machine outputs with about 50 percent accuracy — no better than chance.
Conventional machine-learning systems — such as the ones that led to the speech-recognition algorithms on smartphones — often perform very well on constrained classification tasks, but they must first be trained on huge sets of training data. Humans, by contrast, frequently grasp concepts after just a few examples. That type of “one-shot learning” is something that the researchers designed their system to emulate.
Learning to learn
Like a human subject, however, the system comes to a new task with substantial background knowledge, which in this case is captured by a probabilistic program. Whereas a conventional computer program systematically decomposes a high-level task into its most basic computations, a probabilistic program requires only a very sketchy model of the data it will operate on. Inference algorithms then fill in the details of the model by analyzing a host of examples.
Here, the researchers’ model specified that characters in human writing systems consist of strokes, demarcated by the lifting of the pen, and that the strokes consist of substrokes, demarcated by points at which the pen’s velocity is zero.
Armed with that model, the system then analyzed hundreds of motion-capture recordings of humans drawing characters in several different writing systems, learning statistics on the relationships between consecutive strokes and substrokes as well as on the variation tolerated in the execution of a single stroke.
The system was never trained, however, on the specific writing systems that it analyzed in the researchers’ tests. There, it was simply applying what it had inferred about human writing in general. “It’s learning a bunch of probabilities in a generative program, and that is a generative program for programs,” Tenenbaum says. “Your representation of one of these visual concepts is itself a program that can generate probabilistically different outcomes.”
“I feel that this is a major contribution to science, of general interest to artificial intelligence, cognitive science, and machine learning,” says Zoubin Ghahramani, a professor of information engineering at the University of Cambridge. “Given the major successes of deep learning, the paper also provides a very sobering view of the limitations of such deep-learning methods — which are very data-hungry and perform poorly on the tasks in this paper — and an important alternative avenue for achieving human-level machine learning.”
Synthetic biology technique could make it safer to put engineered bacteria microbes to work outside of the lab.
Scientia — Many research teams are developing genetically modified bacteria that could one day travel around parts of the human body, diagnosing and even treating infection. The bugs could also be used to monitor toxins in rivers or to improve crop fertilization.
However, before such bacteria can be safely let loose, scientists will need to find a way to prevent them from escaping into the wider environment, where they might grow and cause harm.
To this end, researchers at MIT, the Broad Institute of MIT and Harvard, and the Wyss Institute at Harvard University have developed safeguards in the form of two so-called “kill switches,” which can cause the synthetic bacteria to die without the presence of certain chemicals.
In a paper published this week in the journal Nature Chemical Biology, the researchers describe their two kill switches, which they call “Deadman” and “Passcode.”
Stand-alone circuits
There have been a number of attempts to develop kill switches over the past year, according to James Collins, the Termeer Professor of Medical Engineering and Science in MIT’s Department of Biological Engineering and Institute for Medical Engineering and Science (IMES), who led the research.
These include efforts to reprogram the entire genome of the organism to ensure that it requires the presence of certain amino acids or other chemicals in order to survive, divide, and grow.
However, this approach can be both labor- and resource-intensive, and could introduce changes that might make the organism less useful as a monitoring or diagnostic tool, Collins says.
“In our case, we are introducing standalone circuits that can be popped in to any number of different organisms, without needing to rewire or change much of the genome in order for it to accommodate the switch,” he says.
The Deadman switch, for example, is part of a bacterial strain that needs an external chemical to prevent a continuously expressed toxin from killing the cell.
The switch was motivated by the so-called deadman brakes on old trains, which required a conductor to be in constant contact with the handle or pedal in order for the vehicle to move forwards, Collins says.
The system, which builds on previous work in Collin’s lab, consists of a genetic “toggle” switch made up of two transcription factor genes.
The switch can flip between two states, in which either one of the two transcription factor genes is turned on. The researchers altered the expression of these two transcription factors, leading to strong expression for one gene and weak expression for the other.
The presence of a small molecule keeps the switch in its weak state, but as soon as this is removed, the switch will flip to its strong state. The switch is programmed to express various toxins as soon as this strong state is turned on, Collins says.
“If the system does get flipped, by removing the small molecule, it would express toxins at a very high level that could then quite rapidly and readily kill off the bug,” he says.
A cellular logic gate
The Passcode switch, in contrast, acts like a logic gate in that it requires a specific combination of several chemical inputs in order to enable the genetically modified bacteria to survive and proliferate.
The switch consists of a set of modular transcription factors that contain separate domains for sensing small molecules — the inputs — and for regulating gene expression. By mixing and matching these functional domains, the researchers are able to construct hybrid transcription factors in which different small molecule inputs are linked to the control of a specific promoter for gene expression.
If the transcription factors detect that the right combination of small molecules are present in the environment, then the bacteria will survive. But if the correct combination of input signals is not present, the switch kills the bug, according to the paper’s lead author Clement Chan, a postdoc in Collin’s laboratory.
“If any of the required inputs are not correct, then the bug will die,” he says.
By using different transcription factors, the researchers can change the passcode combination of small molecules needed for the cell to survive. In this way the switches can be easily changed to meet the needs of different applications, Chan says.
“It makes our biocontainment system much more flexible, so you can apply the passcode system in a much wider range of applications.”
The switches could also be used to protect a company’s intellectual property, Chan says.
“Imagine that you own a certain bug, and you don’t want your competitors to use it. Then you could incorporate this device so that only people who know the passcode can use your bug,” he says.
Even if a competitor somehow managed to get hold of the passcode, the researcher could simply change it by using different transcription factors, he says.
Scaling up
The new safeguards have exciting possibilities for scaling kill switches in two important directions, according to Farren Isaacs, an assistant professor in the Systems Biology Institute at Yale University, who was not involved in the research.
First, they establish the feasibility of using kill switches across diverse species, Isaacs says.
“They also expand the passcode switches to a large combination of synthetic molecules and transcription factors for many unique sets of biocontained strains and customized cocktails of synthetic small molecules,” he adds.
Having successfully tested the two kill switches in Escherichia coli, the researchers are now hoping to incorporate them into living diagnostic or therapeutic tools, designed to target a variety of bacterial infections, Collins says.
Every now and then I love to do a post on an animal that I love. Now the hedgehog is one of my all time faviourites. Unfortunaley in the UK (where I live) the numbers are declining. There are many factors to why this is but a large contributor to this is down to the lack of safe places for the Hedgehog to live. This post is going to be dedicated to giving lots of information about the hedgehog and how YOU can help them by giving them food in your garden and even helping them to have a safe home to live in.
AAAHHHHH!!!!! look how cute it is :)
General Information on the Hedgehog
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Eulipotyphla Family: Erinaceidae Subfamily: Erinaceinae G. Fischer, 1814
Genera:
Atelerix
Erinaceus
Hemiechinus
Mesechinus
Paraechinus
A hedgehog is any of the spiny mammals of the subfamily Erinaceinae, in the order Eulipotyphla. There are seventeen species of hedgehog in five genera, found through parts of Europe, Asia, and Africa, and in New Zealand by introduction. There are no hedgehogs native to Australia, and no living species native to the Americas (the extinct genus Amphechinus was once present in North America). Hedgehogs share distant ancestry with shrews (family Soricidae), with gymnures possibly being the intermediate link, and have changed little over the last 15 million years. Like many of the first mammals, they have adapted to a nocturnal way of life. Hedgehogs’ spiny protection resembles that of the unrelated rodent porcupines and monotreme echidnas.
Hedgehogs are easily recognized by their spines, which are hollow hairs made stiff with keratin.[5] Their spines are not poisonous or barbed and unlike the quills of a porcupine, do not easily detach from their bodies. However, the immature animal’s spines normally fall out as they are replaced with adult spines. This is called “quilling”. Spines can also shed when the animal is diseased or under extreme stress.
Hedgehogs are primarily nocturnal, though some species can also be active during the day. Hedgehogs sleep for a large portion of the day under bush, grass, or rock, or most often in dens dug in the ground, with varying habits among the species. All wild hedgehogs can hibernate, though not all do, depending on temperature, species, and abundance of food.
Hedgehog Defense
A defense that all species of hedgehogs possess is the ability to roll into a tight ball, causing all of the spines to point outwards. Since the effectiveness of this strategy depends on the number of spines, some desert hedgehogs that evolved to carry less weight are more likely to flee or even attack, ramming an intruder with the spines; rolling into a spiny ball is for those species a last resort. The various species are prey to different predators: while forest hedgehogs are prey primarily to birds (especially owls) and ferrets, smaller species like the long-eared hedgehog are prey to foxes, wolves and mongooses.
The hedgehog’s back contains two large muscles that control the position of the quills. The average hedgehog has about 5,000 to 6,500 quills that are strong on the outer surface but filled with air pockets on the inside. When the creature is rolled into a ball, the quills on the back protect the tucked head, feet, and belly, which are not quilled. This is the hedgehog’s last but most successful form of defense.
Hedgehogs are fairly vocal and communicate through a combination of grunts, snuffles and/or squeals, depending on species. Actually just on this, where I live we have quite a few hedgehogs, and to say they are fairly vocal is an understatement. I am often outside in the early hours, stargazing. While the early morning quiet sets in, you can often hear them shuffling about and grunting quite loud. The first time I heard it, I nearly wet myself. Upon finding a torch, low and behold was a little hedgehog going about his own business, snuffling about near my feet. To be fair he didn’t even seem too concerned that I was shining a bright light in his face, he/she just kinda looked as if to say “and what?!” I swear, if he could raise his middle finger up at this point…I think he would have.
Hedgehog Diet
Hedgehogs are omnivorous. They feed on insects, snails, frogs and toads, snakes, bird eggs, carrion, mushrooms, grass roots, berries, melons and watermelons. Berries constitute a major part of an Afghan hedgehog’s diet in early spring after hibernation.
***IMPORTANT NOTE*** You should never leave ham and milk out for a hedgehog. People often do this as they think they will help fatten the hedgehog up for winter; however, ham does not agree with them and they are lactose intolerant. The best thing is a bowl of water in a shallow dish and some chopped up worms or slugs, but if you’re not an avid gardener, some meat based cat and dog food (not fish-based), crushed cat biscuits, or chopped boiled eggs can be great.
Hedgehog Hibernation
Hedgehogs are one of the few mammals that are true hibernators. During hibernation hedgehogs are not really asleep, instead they drop their body temperature to match their surroundings and enter a state of torpor. This allows them to save a lot of energy but slows down all other bodily functions making normal activity impossible.
Hedgehogs usually hibernate from October/November through to March/April. Research has shown that each individual is likely to move nesting sites at least once during this period and so can sometimes be seen out and about. During mild winters hedgehogs can remain active well into November and December.
While in hibernation the hedgehog’s fuel supply comes from the fat stores it has built up over the summer. Eating enough before hibernation is vital and this is when supplementary feeding (as mentioned above) can prove important to hedgehogs.
Hedgehog Hibernation Survey 2014
Hedgehog Breeding
Hedgehogs reach sexual maturity in their second year of life, and after this can breed every year until death. Reproduction occurs any time between April and September, but the period of greatest activity, ‘the rut’, occurs in May and June in Britain.
Males attempt to woo females in lengthy encounters that involve much circling and rhythmic snorting and puffing. The commotion can attract rival males to the scene and courtship can thus be interrupted as interlopers are confronted and rival males square up to one another; head-butting and chases are not uncommon.
Long eared desert hedgehog Hemiechinus auritus Gobi desert, Mongolia
The actual process of mating is a predictably delicate operation, with the female having to adopt a special body position with her spines flattened as the male mounts from behind. Radio-tracking studies have shown hedgehogs to be promiscuous with both males and females often having several different mates in a single season.
Hedgehog babies are called hoglets Most baby hedgehogs are born in June and July, with an average litter size of four or five young, of which two or three are usually weaned successfully. The mother is liable to desert or even eat the young if she is disturbed. Young hedgehogs will leave the nest when they are around three to four weeks old to go on foraging trips with their mother. After around ten days of foraging with their mother the young will wander off on their own.
Females are capable of having a second litter in late September or October but these young are unlikely to survive the winter. In Britain it is thought unlikely that female hedgehogs ever manage to successfully rear two litters in a season as the young from the second litter are unable to put on enough weight to survive hibernation. These late litters can lead to ‘autumn orphans’ still foraging around well into winter sometimes in the day time and often looking underweight.
Hedgehog Facts
The hedgehog got its name because of its peculiar foraging habits. They root through hedges and other undergrowth in search of their favourite food – small creatures such as insects, worms, centipedes, snails, mice, frogs, and snakes. As it moves through the hedges it emits pig-like grunts — thus, the name hedgehog.
The hedgehog is nocturnal, coming out at night and spending the day sleeping in a nest under bushes or thick shrubs
Their coats are thick and spiny, providing them with a formidable defence against predators such as the fox. When they feel alarmed or intimidated, they will curl up into a spiny ball to protect its vulnerable stomach.
They have about 5000 spines. Each spine lasts about a year then drops out and a replacement grows.
The spines are hollow and springy with a flexible neck and they are erected by muscles. At the base there is a smooth ball which bends on impact.
There may be up to 500 fleas on one hedgehog but the specific hedgehog flea (known as Archaepsylla erinacei) rarely bites humans.
They also have a habit when stimulated by a strong smell or taste to self-anoint – this means they cover their prickles in foamy saliva. No-one is certain why it does this.
While hunting for food, they rely primarily upon their senses of hearing and smell because their eyesight is weak though their eyes are adapted for night-time vision.
They have a particularly long, extending snout beyond the front of their mouth which they use to help them forage for food.
The diet of a hedgehog has claimed it the reputation as being the ‘gardener’s friend’ as it includes so many ‘pests’. Frequently food put out for dogs and cats in town and city gardens also provides a meal for them and it is certainly a good way to encourage one into your own garden.
Hedgehogs are usually solitary, usually pairing up only to mate. When they mate they often make loud snuffling noises. The male circles the female, sometimes for hours, to persuade her to mate. They will separate thereafter and the male takes no part in rearing the family.
The young are born in litters ranging from one to eleven. They remain with their mothers for only four to seven weeks before heading out on their own. Among the predators females must guard against during this period are other male hedgehogs, which will sometimes prey upon the young of their species. Hedgehog mothers have also been known to eat their young if the nest is disturbed, though they sometimes simply move them to a new nest.
Baby hedgehogs are born blind after 32 days and their spines are soft. However a late litter born in September seldom survive their first winter. The young are suckled by their mother until they are able to hunt for themselves. After about four weeks, the mother will take the young out on their first foraging trip and after ten days, the family will separate.
European hedgehogs in the UK hibernate throughout winter. They feed as much as possible during the autumn and in around October build its nests of leaves and grass in which to hibernate.
There are 17 species of hedgehog.
Hedgehogs in cold climes hibernate over the winter. In warmer climates such as deserts they sleep through heat and drought in a similar process called aestivation. In more temperate areas they remain active all year.
A group of hedgehogs is called an “array.”
Hedgehogs are illegal in Maine, Arizona, California, Georgia, Pennsylvania, Hawaii, and New York City.
Hedgehogs rely on hearing and smell because they have very poor eyesight.
Unlike porcupine quills, hedgehog spikes are not barbed, and they’re not poisonous.
Hedgehogs are largely immune to snake venom.
The sea urchin is actually named after the hedgehog. Before the more adorable name came into use, the spiky mammals were called “urchins” and thus inspired the name of the similarly spiky sea creatures.
When exposed to pungent smells or tastes, hedgehogs exhibit a behavior called “self-anointing” in which they rub frothy saliva on their quills. When the animal encounters a new scent, it will lick and bite the source, then form a scented froth in its mouth and paste it on its spines with its tongue. The purpose of this habit is unknown, but some experts believe anointing camouflages the hedgehog with the new scent of the area and provides a possible poison or source of infection to predators poked by their spines. Anointing is sometimes also called anting because of a similar behavior in birds.
How to help the Hedgehog
Encouraging hedgehogs into your garden
Place a small dish of dog or cat food (although no fish varieties) alongside some water to encourage hedgehogs into your garden.
If you have a garden wall or fence, remove a brick from the bottom or cut a hole (roughly 15cm/6in in diameter). This will allow the hedgehog to roam freely in and out of the garden.
One way to attract these friendly creatures is to place a wooden nesting box in your garden. Cover the box in vegetation and place in a secluded corner. You can buy nesting boxes here (third party link, however if you google “buy hedgehog home” you will find something) or why not try making one yourself. Here is an awesome link from the rspb with some great instructions to make a home for hedgehogs and other animals to. Another site to help you build a simple home for your little hog’s from Gardener’s World Alternatively, you can leave an area of your garden to grow wild, as hedgehogs like to nest in long grass, shrubs, flowers and nettles.
How to make a Hedgehog Home Videos
Video One: Hedgehog Homes from Laura Brady and her Father
Video Two: Making a Hedgehog House (Walk through)
Hedgehog Information Videos
Hedgehog Mating Rituals – Attenborough – Life of Mammals – BBC
