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Hidden black holes: New system explains why we have found fewer black holes than expected

Hidden black holes: New system explains why we have found fewer black holes than expected | Amazing Science | Scoop.it

If you want your pet black hole to be visible, you must feed it regularly. Only when a black hole gorges on a steady diet of gas or other matter does it shine. The disk of matter that orbits it heats up and emits large amounts of light, especially in X-rays. If you have one of the supermassive black holes at the centers of galaxies, feeding it matter can create one of the brightest objects in the Universe.

 

But the smaller ones should also be pretty visible. And while astronomers expect and have observed black holes comparable in mass to stars, their numbers are fewer than expected, even after decades of searching. Perhaps, as a new paper suggests, this is because many black holes are hidden by an opaque, donut-shaped disk of matter.

 

J. M. Corral-Santana and colleagues based this hypothesis on a detailed study of a relatively faint, fluctuating X-ray source in the Milky Way. Their observations in X-ray and visible light revealed the signs of a binary system: an ordinary star in orbit around a black hole, similar to other systems, but with some key differences. For one, the star and black hole were so close together that the orbital period of the system was only 2.8 hours. For another, the matter being drawn off the star was obscuring the black hole when viewed from Earth. The authors hypothesized that many other black holes may be similarly hidden, and future searches should take that possibility into account.

 

Stellar-mass black holes are the remnants of the cores of stars which exploded in supernovae and are at least 20 times the mass of the Sun. Black holes in this mass range have been discovered in binary systems, where their companion is an ordinary star. The transfer of mass from the companion onto the black hole creates an accretion disk: a hot, rapidly rotating platter that emits a great deal of X-ray light. The first black hole discovered, Cygnus X-1, was found through these emissions.

 

However, in nearly 50 years of X-ray observations, only about 50 black holes candidates have been known in the Milky Way, of which only 18 are confirmed. None of them exhibit eclipses, where the companion star or accretion disk block the X-ray emission. That's a somewhat surprising result, as it may imply we're only identifying systems we see from a privileged angle, one where our telescopes peer "down" onto the system. Since a bright black hole system that undergoes eclipses was identified in the M33 (Triangulum) galaxy, astronomers know it does happen.

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20,000+ FREE Online Science and Technology Lectures from Top Universities

20,000+ FREE Online Science and Technology Lectures from Top Universities | Amazing Science | Scoop.it

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Futuristic fusion reactors could make carbon-free power as early as 2019

Futuristic fusion reactors could make carbon-free power as early as 2019 | Amazing Science | Scoop.it

Dr. David Kirtley comes across as a smart, practical guy with a head for business. That creates some cognitive dissonance when he explains that his Redmond startup is developing fusion energy.


You’ve heard about fusion energy, the amazing power source of the future. Nuclear scientists promise fusion will have all the best qualities of conventional nuclear and natural-gas energy but none of the downsides. Fusion is carbon-free like today’s atomic power, but without the need to protect a thousand future generations from radioactive waste. Other than being mind-blowing, fusion would be relatively safe — no China Syndrome, no contamination, no weapons-grade materials to proliferate.


Thus far, fusion energy always has been an unfinished science that’s 50 years and $50 billion from commercialization. Seven nations are collaborating to build an experimental fusion reactor in France as an $11 billion proof of concept that still won’t produce electricity when it’s operational in 2027.


Dr. Kirtley’s company Helion Energy has taken the proven parts of fusion science and combined them into a design that can be commercially deployable within six years. That would be a decade ahead of Helion’s Bellevue neighbor, TerraPower LLC, a startup funded in part by Nathan Myhrvold and Bill Gates to build a traveling wave reactor that runs on uranium.


Helion Energy last week won the top prize in the Energy Generation category at the Cleantech Open Global Forum in Silicon Valley. The prize comes with a $5,000 check and a long menu of in-kind services. The audience also gave Helion a People’s Choice Award. The annual competition culminates a nine-month business accelerator for Cleantech startups.


The team at Helion comes out of the University of Washington and Mathematical Sciences Northwest. At its headquarters in Redmond, Helion has a working prototype that they say proves their design works. Deuterium gas goes in two ends of the device and produces a pair of plasmas per second. Plasma is responsible for the glow of lightning, neon lights and the Sun. As the two plasmas collide in the center, a magnetic pulse generates electricity.


At the Global Forum, Dr. Kirtley told me his design is compact, modular and competitive in today’s market. In the footprint of a semi trailer, each module will produce 50 megawatts of electricity (it would take ten of them to equal the output of a conventional power plant). The deuterium fuel is derived from seawater. The byproduct is a harmless stream of helium.


Helion Energy is raising $35 million to build a fusion reactor core that will demonstrate electricity production from fusion energy. Its technology previously received $4 million in funding from the U.S. Department of Energy.


“Helion isn’t looking for funding to do more science,” says Kirtley. “We already proved our technology. We’re now ready to start commercializing fusion energy.”

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Who's your daddy? Researchers program computer to find out

Who's your daddy? Researchers program computer to find out | Amazing Science | Scoop.it
A University of Central Florida research team has developed a facial recognition tool that promises to be useful in rapidly matching pictures of children with their biological parents and in potentially identifying photos of missing children as they age.


The work verifies that a computer is capable of matching pictures of parents and their children. The study will be presented at the nation's premier event for the science of computer vision - the IEEE Computer Vision and Pattern Recognition conference in Columbus, Ohio, which begins Monday, June 23. Graduate Student Afshin Dehfghan and a team from UCF's Center for Research in Computer Vision started the project with more than 10,000 online images of celebrities, politicians and their children.


"We wanted to see whether a machine could answer questions, such as 'Do children resemble their parents?' 'Do children resemble one parent more than another?' and 'What parts of the face are more genetically inspired?'" he said.


Anthropologists have typically studied these questions. However Dehghan and his team are advancing a new wave of computational science that uses the power of a mechanical "mind" to evaluate data completely objectively – without the clutter of subjective human emotions and biases. The tool could be useful to law enforcement and families in locating missing children.


"As this tool is developed I could see it being used to identify long-time missing children as they mature," said Ross Wolf, associate professor of criminal justice at UCF.


Wolf said that facial recognition technology is already heavily used by law enforcement, but that it has not been developed to the point where it can identify the same characteristics in photos over time, something this technology could have the capability to do. Dehghan said he is planning to expand on the work in that area by studying how factors such as age and ethnicity affect the resemblance of facial features.

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Transplanting the TBX18 gene into injured hearts creates biological pacemakers

Transplanting the TBX18 gene into injured hearts creates biological pacemakers | Amazing Science | Scoop.it
Cardiologists have developed a minimally invasive gene transplant procedure that changes unspecialized heart cells into "biological pacemaker" cells that keep the heart steadily beating.


The laboratory animal research, published online and in today's print edition of the peer-reviewed journalScience Translational Medicine, is the result of a dozen years of research with the goal of developing biological treatments for patients with heart rhythm disorders who currently are treated with surgically implanted pacemakers. In the United States, an estimated 300,000 patients receive pacemakers every year.


"We have been able, for the first time, to create a biological pacemaker using minimally invasive methods and to show that the biological pacemaker supports the demands of daily life," said Eduardo Marbán, MD, PhD, director of the Cedars-Sinai Heart Institute, who led the research team. "We also are the first to reprogram a heart cell in a living animal in order to effectively cure a disease."


These laboratory findings could lead to clinical trials for humans who have heart rhythm disorders but who suffer side effects, such as infection of the leads that connect the device to the heart, from implanted mechanical pacemakers.


Eugenio Cingolani, MD, the director of the Heart Institute's Cardiogenetics-Familial Arrhythmia Clinic who worked with Marbán on biological pacemaker research team, said that in the future, pacemaker cells also could help infants born with congenital heart block.


"Babies still in the womb cannot have a pacemaker, but we hope to work with fetal medicine specialists to create a life-saving catheter-based treatment for infants diagnosed with congenital heart block," Cingolani said. "It is possible that one day, we might be able to save lives by replacing hardware with an injection of genes."


"This work by Dr. Marbán and his team heralds a new era of gene therapy, in which genes are used not only to correct a deficiency disorder, but to actually turn one kind of cell into another type," said Shlomo Melmed, dean of the Cedars-Sinai faculty and the Helene A. and Philip E. Hixson Distinguished Chair in Investigative Medicine.


In the study, laboratory pigs with complete heart block were injected with the gene called TBX18 during a minimally invasive catheter procedure. On the second day after the gene was delivered to the animals' hearts, pigs who received the gene had significantly faster heartbeats than pigs who did not receive the gene. The stronger heartbeat persisted for the duration of the 14-day study.

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Researchers develop powerful single-cell epigenetic methylation mapping to study environmental effects on DNA

Researchers develop powerful single-cell epigenetic methylation mapping to study environmental effects on DNA | Amazing Science | Scoop.it

Researchers at the BBSRC-funded Babraham Institute, in collaboration with the Wellcome Trust Sanger Institute Single Cell Genomics Centre, have developed a powerful new single-cell technique to help investigate how the environment affects our development and the traits we inherit from our parents. The technique can be used to map all of the ‘epigenetic marks’ on the DNA within a single cell.  This single-cell approach will boost understanding of embryonic development, could enhance clinical applications like cancer therapy and fertility treatments, and has the potential to reduce the number of mice currently needed for this research.


‘Epigenetic marks’ are chemical tags or proteins that mark DNA and act as a kind of cellular memory. They do not change the DNA sequence but record a cell’s experiences onto the DNA, which allows cells to remember an experience long after it has faded. Placing these tags is part of normal development; they tell genes whether to be switched on or off and so can determine how the cell develops. Different sets of active genes make a skin cell different from a brain cell, for example. However, environmental cues such as diet can also alter where epigenetic tags are laid down on DNA and influence an organism’s long-term health.


Dr Gavin Kelsey, from the Babraham Institute, said: “The ability to capture the full map of these epigenetic marks from individual cells will be critical for a full understanding of early embryonic development, cancer progression and aid the development of stem cell therapies.


“Epigenetics research has mostly been reliant on using the mouse as a model organism to study early development. Our new single-cell method gives us an unprecedented ability to study epigenetic processes in human early embryonic development, which has been restricted by the very limited amount of tissue available for analysis.”


The new research, published in Nature Methods, offers a new single-cell technique capable of analysing DNA methylation – one of the key epigenetic marks – across the whole genome. The method treats the cellular DNA with a chemical called bisulphite. Treated DNA is then amplified and read on high-throughput sequencing machines to show up the location of methylation marks and the genes being affected.


These analyses will help to define how epigenetic changes in individual cells during early development drive cell fate. Current methods observe epigenetic marks in multiple, pooled cells. This can obscure modifications taking place in individual cells at a time in development when each cell has the potential to form in a unique way. The new method has already revealed that many of the methylation marks that differ between individual cells are precisely located in sites that control gene activity.

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Proton Spin Mystery Gains a New Clue

Proton Spin Mystery Gains a New Clue | Amazing Science | Scoop.it

Physicists long assumed a proton’s spin came from its three constituent quarks. New measurements suggest particles called gluons make a significant contribution.


Protons have a constant spin that is an intrinsic particle property like mass or charge. Yet where this spin comes from is such a mystery it’s dubbed the “proton spin crisis.” Initially physicists thought a proton’s spin was the sum of the spins of its three constituent quarks. But a 1987 experiment showed that quarks can account for only a small portion of a proton’s spin, raising the question of where the rest arises. The quarks inside a proton are held together by gluons, so scientists suggested perhaps they contribute spin. That idea now has support from a pair of studies analyzing the results of proton collisions inside the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, N.Y.
 
Physicists often explain spin as a particle’s rotation, but that description is more metaphorical than literal. In fact, spin is a quantum quantity that cannot be described in classical terms. Just as a proton is not really a tiny marble but rather a jumble of phantom particles appearing and disappearing continuously, its spin is a complex probabilistic property. Yet it is always equal to one half.
 
Quarks also have a spin of one half. Physicists originally assumed that two of the proton’s three quarks were always spinning in opposite directions, canceling one another out, leaving the remaining one half as the proton’s total spin. “That was the naïve idea 25 years ago,” says Daniel de Florian of the University of Buenos Aires, leader of one of the new papers, which was published July 2, 2014 in Physical Review Letters. “By the end of the ‘80s it was possible to measure the contribution of the spin of the quarks to the spin of the proton, and the first measurement showed it was 0 percent. That was a very big surprise.” Later measurements actually suggested quarks can contribute up to 25 percent of the proton’s total spin, but that still leaves the lion’s share unaccounted for.
 
Gluons are also present inside protons as the representatives of the strong nuclear force, a fundamental interaction that binds the quarks together. Gluons each have a spin of 1, and depending on which direction it is they could add up to make most of rest of the proton’s spin. Measuring their contribution is a tricky task. RHIC is the only experiment that can address the question, because it is the only particle accelerator built to collide “spin-polarized” protons, meaning that the particles are all spinning in a certain direction when they crash. (At the more powerful Large Hadron Collider in Switzerland, the particles’ spins are not aligned.)
 
When two protons slam together, their interaction is controlled by the strong force, so gluons are intimately involved. If gluon spin is an important ingredient of proton spin, then the orientation of the colliding protons’ spins should affect the outcome. Scientists would expect collisions between two protons whose spins were aligned would happen at a different frequency than collisions between those spinning in opposite directions. And according to recent data from RHIC, there is a difference. “If there is no preferred position, the difference will be exactly zero,” says University of Oxford physicist Juan Rojo, a member of the so-called NNPDF Collaboration that wrote the second paper, which was submitted to Nuclear Physics B.


“Since the asymmetry is not zero, this tells us the distribution of the spin is not trivial.” Rojo’s team calculated that gluons probably contribute about half the spin that quarks do to the proton. De Florian and his colleagues analyzed the same data from RHIC, but used a different mathematical analysis to calculate the gluon contribution. They also found that gluon spin must be significantly involved. “This data for the first time shows the gluon polarization is actually nonzero; we see the gluons are polarized,” de Florian says. “Basically they could be responsible for the rest of the proton spin, but the uncertainty is very large.”

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Fecal Transplants of Bacteria Let Packrats Eat Poisonous Creosote Diet

Fecal Transplants of Bacteria Let Packrats Eat Poisonous Creosote Diet | Amazing Science | Scoop.it

Woodrats lost their ability to eat toxic creosote bushes after antibiotics killed their gut microbes. Woodrats that never ate the plants were able to do so after receiving fecal transplants with microbes from creosote-eaters, University of Utah biologists found.


The new study confirms what biologists long have suspected: bacteria in the gut – and not just liver enzymes – are “crucial in allowing herbivores to feed on toxic plants,” says biologist Kevin Kohl, a postdoctoral researcher and first author of the paper published online today in the journal Ecology Letters.


Many plants produce toxic chemicals, which they use as a defense against herbivores, or plant-eating animals. A toxic resin coats the leaves of the creosote bush; juniper toxins are found inside juniper needles.

Most mammals are herbivores. Some face serious challenges: their bodies must handle up to hundreds of toxic chemicals from the plants they consume each day. “Plant toxins determine which plants a herbivore can eat,” says Kohl.


Liver enzymes help animals detoxify such poisons. Researchers previously isolated toxin-degrading microbes from herbivores, but Kohl and Dearing say that, until now, scientists have lacked strong evidence for what has been conventional wisdom: Gut microbes also help some herbivores eat toxic plants.


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Barnacle cement: Nature's strongest glue is a two-component adhesive

Barnacle cement: Nature's strongest glue is a two-component adhesive | Amazing Science | Scoop.it

Over a 150 years since it was first described by Darwin, scientists are finally uncovering the secrets behind the super strength of barnacle glue. 

Still far better than anything we have been able to develop synthetically, barnacle glue – or cement - sticks to any surface, under any conditions.

But exactly how this superglue of superglues works has remained a mystery – until now.


An international team of scientists led by Newcastle University, UK, and funded by the US Office of Naval Research, have shown for the first time that barnacle larvae release an oily droplet to clear the water from surfaces before sticking down using a phosphoprotein adhesive.


Publishing their findings this week in the prestigious academic journal Nature Communications, author Dr Nick Aldred says the findings could pave the way for the development of novel synthetic bioadhesives for use in medical implants and micro-electronics. The research will also be important in the production of new anti-fouling coatings for ships.


Thoracian barnacles rely heavily upon their ability to adhere to surfaces and are environmentally and economically important as biofouling pests. Their adhesives have unique attributes that define them as targets for bio-inspired adhesive development. With the aid of multi-photon and broadband coherent anti-Stokes Raman scattering microscopies, we report that the larval adhesive of barnacle cyprids is a bi-phasic system containing lipids and phosphoproteins, working synergistically to maximize adhesion to diverse surfaces under hostile conditions. Lipids, secreted first, possibly displace water from the surface interface creating a conducive environment for introduction of phosphoproteins while simultaneously modulating the spreading of the protein phase and protecting the nascent adhesive plaque from bacterial biodegradation. The two distinct phases are contained within two different granules in the cyprid cement glands, implying far greater complexity than previously recognized. Knowledge of the lipidic contribution will hopefully inspire development of novel synthetic bioadhesives and environmentally benign antifouling coatings.

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Speedy computation enables scientists to reconstruct an animal's development cell by cell

Speedy computation enables scientists to reconstruct an animal's development cell by cell | Amazing Science | Scoop.it
Researchers have developed a new computational method that can rapidly track the three-dimensional movements of cells in such data-rich images. Using the method, scientists can essentially automate much of the time-consuming process of reconstructing an animal's developmental building plan cell by cell.


Recent advances in imaging technology are transforming how scientists see the cellular universe, showing the form and movement of once grainy and blurred structures in stunning detail. But extracting the torrent of information contained in those images often surpasses the limits of existing computational and data analysis techniques, leaving scientists less than satisfied.


Now, researchers at the Howard Hughes Medical Institute's Janelia Research Campus have developed a way around that problem. They have developed a new computational method that can rapidly track the three-dimensional movements of cells in such data-rich images. Using the method, the Janelia scientists can essentially automate much of the time-consuming process of reconstructing an animal's developmental building plan cell by cell.


Philipp Keller, a group leader at Janelia, led the team that developed the computational framework. He and his colleagues, including Janelia postdoc Fernando Amat, Janelia group leader Kristin Branson and former Janelia lab head Eugene Myers, who is now at the Max Plank Institute of Molecular Cell Biology and Genetics, have used the methodto reconstruct cell lineage during development of the early nervous system in a fruit fly. Their method can be used to trace cell lineages in multiple organisms and efficiently processes data from multiple kinds of fluorescent microscopes.


The scientists describe their approach in a paper published online on July 20, 2014, in Nature Methods.


"With this fairly fast, simple approach, we can solve easy cases fairly efficiently," Keller says. Those cases make up about 95 percent of the data. "In harder cases, where we might have mistakes, we use heavier machinery."


He explains that in instances where cells are harder to track -- because image quality is poor or cells are crowded, for example -- the computer draws on additional information. "We look at what all the cells in that neighborhood do a little bit into the future and a little bit into the past," Keller explains. Informative patterns usually emerge from that contextual information. The strategy takes more computing power than the initial tactics. "We don't want to do it for all the cells," Keller says. "But we try to crack these hard cases by gathering more information and making better informed decisions."


All of these steps can be carried out as quickly as images are acquired by the microscope, and the result is lineage information for every cell. "You know the path, you know where it is at a certain time point. You know it divided at a certain point, you know the daughter cells, you know what mother cell it came from," Keller says.


New York TImes article


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Steam from the sun: New sponge-like material converts 85% of solar energy into steam

Steam from the sun: New sponge-like material converts 85% of solar energy into steam | Amazing Science | Scoop.it

A new material structure developed at MIT generates steam by soaking up the sun. The structure — a layer of graphite flakes and an underlying carbon foam — is a porous, insulating material structure that floats on water. When sunlight hits the structure’s surface, it creates a hotspot in the graphite, drawing water up through the material’s pores, where it evaporates as steam. The brighter the light, the more steam is generated.


The new material is able to convert 85 percent of incoming solar energy into steam — a significant improvement over recent approaches to solar-powered steam generation. What’s more, the setup loses very little heat in the process, and can produce steam at relatively low solar intensity. This would mean that, if scaled up, the setup would likely not require complex, costly systems to highly concentrate sunlight.


Hadi Ghasemi, a postdoc in MIT’s Department of Mechanical Engineering, says the spongelike structure can be made from relatively inexpensive materials — a particular advantage for a variety of compact, steam-powered applications.


“Steam is important for desalination, hygiene systems, and sterilization,” says Ghasemi, who led the development of the structure. “Especially in remote areas where the sun is the only source of energy, if you can generate steam with solar energy, it would be very useful.”


Ghasemi and mechanical engineering department head Gang Chen, along with five others at MIT, report on the details of the new steam-generating structure in the journal Nature Communications.


Today, solar-powered steam generation involves vast fields of mirrors or lenses that concentrate incoming sunlight, heating large volumes of liquid to high enough temperatures to produce steam. However, these complex systems can experience significant heat loss, leading to inefficient steam generation.


Recently, scientists have explored ways to improve the efficiency of solar-thermal harvesting by developing new solar receivers and by working with nanofluids. The latter approach involves mixing water with nanoparticles that heat up quickly when exposed to sunlight, vaporizing the surrounding water molecules as steam. But initiating this reaction requires very intense solar energy — about 1,000 times that of an average sunny day.


By contrast, the MIT approach generates steam at a solar intensity about 10 times that of a sunny day — the lowest optical concentration reported thus far. The implication, the researchers say, is that steam-generating applications can function with lower sunlight concentration and less-expensive tracking systems.  

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Google Strikes Smart Contact Lens deal to track Diabetes and Cure Farsightedness

Google Strikes Smart Contact Lens deal to track Diabetes and Cure Farsightedness | Amazing Science | Scoop.it

With Glass and Android Wear, Google has already invested a lot of time and resources into developing the next-generation of wearables, but it's another of its eye-focused projects that has today received its first major boost. The search giant's secret Google[x] team has confirmed that it's licensed its smart eyewear to healthcare specialist Novartis, which will develop the technology into a product that can improve eye care and help manage diseases and conditions.


As part of the agreement, Google[x] and Novartis' eye care division Alcon will create smart lenses that feature "non-invasive sensors, microchips and other miniaturized electronics" and focus on two main areas. The first will provide a way for diabetic patients to keep on top of their glucose levels by measuring the sugar levels in their tear fluid, feeding the data back to a smartphone or tablet. The second solution aims to help restore the eye's natural focus on near objects, restoring clear vision to those who are only farsighted (presbyopia).


Google's role will be to develop the tiny electronics needed to collect data and will also take care of the low-power chip designs and fabrication. Alcon, on the other hand, will apply its medical knowledge to develop commercial versions of the smart contact lens. "Our dream is to use the latest technology in the miniaturization of electronics to help improve the quality of life for millions of people," says Google co-founder Sergey Brin. "We are very excited to work with Novartis to make this dream come true."


Via TechinBiz, Farid Mheir, Sílvia Dias
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Pier Bécotte's curator insight, July 16, 9:31 AM

Google frappe intelligente lentilles de contact accord pour suivre le diabète et fixer l'hypermétropie

Farid Mheir's curator insight, July 17, 1:44 PM

Strangely I never wrote about this but it certainly is worth a mention because Google has now made very strong moves towards "atoms and not bits" as Sergei Brin put it a few days ago, stating that Google has invested in search (bits) for a long time and is now complementing its focus to physical devices (atoms) such as the self driving car or here the contact lens.


This story is of particular importance as it shows that Google is not in the business of making contact lenses (or cars) but providing the R&D to disrupt industries that are not making the radical shifts they can by using digital technology.


Also consider:.

[INFOGRAPHIC] The Existing Wearable Technology Landscape via @WearableWorld http://sco.lt/7pTHPN

IV Technology's curator insight, July 18, 11:18 AM

siguiente paso es hacer diagnosticos con scaner y que se prenda una luz roja para que vayamos al servicio.... Hospital

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It's here: First case of Chikungunya Virus contracted in the U.S.

It's here: First case of Chikungunya Virus contracted in the U.S. | Amazing Science | Scoop.it

The CDC reports a man in Florida caught the mosquito-borne virus that's been taking the Caribbean by storm. U.S. health officials today announced the first locally acquired case of chikungunya, a mosquito-borne virus that's become prevalent in the Caribbean in recent months.


The CDC reports a male patient in Florida was diagnosed with the virus, and had not recently traveled outside the country. Federal and Florida state health officials are investigating how the man could have contracted the virus domestically. They're also working to monitor the region in an effort to prevent additional infections and educate residents on ways to prevent mosquito bites. Local transmission occurs when the insect bites a person with the infection and then transmits the virus by biting others.


Chikungunya -- an African word that loosely translates as "contorted with pain" -- is most commonly found in Asia and Africa, and began appearing in the Caribbean last winter. Between 2006 and 2013, there were approximately 28 reported cases of the virus each year in travelers returning to the U.S. This year, travel-related chikungunya has been diagnosed in patients who have recently visited to the Caribbean.


Chikungunya virus is transmitted to people by mosquitoes. The most common symptoms of chikungunya virus infection are fever and joint pain. Other symptoms may include headache, muscle pain, joint swelling, or rash. Outbreaks have occurred in countries in Africa, Asia, Europe, and the Indian and Pacific Oceans. In late 2013, chikungunya virus was found for the first time in the Americas on islands in the Caribbean. Chikungunya virus is not currently found in the continental United States. There is a risk that the virus will be imported to new areas by infected travelers. There is no vaccine to prevent or medicine to treat chikungunya virus infection. Travelers can protect themselves by preventing mosquito bites. When traveling to countries with chikungunya virus, use insect repellent, wear long sleeves and pants, and stay in places with air conditioning or that use window and door screens.

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Is The Universe A Multiverse Bubble? Physicists Are Trying To Bring It Into The Realm Of Testable Science

Never mind the big bang; in the beginning was the vacuum. The vacuum simmered with energy (variously called dark energy, vacuum energy, the inflation field, or the Higgs field). Like water in a pot, this high energy began to evaporate – bubbles formed.


Each bubble contained another vacuum, whose energy was lower, but still not nothing. This energy drove the bubbles to expand. Inevitably, some bubbles bumped into each other. It’s possible some produced secondary bubbles. Maybe the bubbles were rare and far apart; maybe they were packed close as foam.


Proponents of the multiverse theory argue that it’s the next logical step in the inflation story. Detractors argue that it is not physics, but metaphysics – that it is not science because it cannot be tested. After all, physics lives or dies by data that can be gathered and predictions that can be checked.


That’s where Perimeter Associate Faculty member Matthew Johnson comes in. Working with a small team that also includes Perimeter Faculty member Luis Lehner, Johnson is working to bring the multiverse hypothesis firmly into the realm of testable science.

“That’s what this research program is all about,” he says. “We’re trying to find out what the testable predictions of this picture would be, and then going out and looking for them.”


Specifically, Johnson has been considering the rare cases in which our bubble universe might collide with another bubble universe. He lays out the steps: “We simulate the whole universe. We start with a multiverse that has two bubbles in it, we collide the bubbles on a computer to figure out what happens, and then we stick a virtual observer in various places and ask what that observer would see from there.”


“Simulating the universe is easy,” says Johnson. Simulations, he explains, are not accounting for every atom, every star, or every galaxy – in fact, they account for none of them. “We’re simulating things only on the largest scales,” he says. “All I need is gravity and the stuff that makes these bubbles up. We’re now at the point where if you have a favourite model of the multiverse, I can stick it on a computer and tell you what you should see.”


That’s a small step for a computer simulation program, but a giant leap for the field of multiverse cosmology. By producing testable predictions, the multiverse model has crossed the line between appealing story and real science.


In fact, Johnson says, the program has reached the point where it can rule out certain models of the multiverse: “We’re now able to say that some models predict something that we should be able to see, and since we don’t in fact see it, we can rule those models out.”


For instance, collisions of one bubble universe with another would leave what Johnson calls “a disk on the sky” – a circular bruise in the cosmic microwave background. That the search for such a disk has so far come up empty makes certain collision-filled models less likely.


Meanwhile, the team is at work figuring out what other kinds of evidence a bubble collision might leave behind. It’s the first time, the team writes in their paper, that anyone has produced a direct quantitative set of predictions for the observable signatures of bubble collisions. And though none of those signatures has so far been found, some of them are possible to look for.


The real significance of this work is as a proof of principle: it shows that the multiverse can be testable. In other words, if we are living in a bubble universe, we might actually be able to tell.

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Propellantless propulsion with Electric solar wind sail for cheaper and faster space missions

Propellantless propulsion with Electric solar wind sail for cheaper and faster space missions | Amazing Science | Scoop.it

A paper analyses the potential of the electric solar wind sail for solar system space missions. Applications studied include fly-by missions to terrestrial planets (Venus, Mars and Phobos, Mercury) and asteroids, missions based on non-Keplerian orbits (orbits that can be maintained only by applying continuous propulsive force), one-way boosting to outer solar system, off-Lagrange point space weather forecasting and low-cost impactor probes for added science value to other missions. We also discuss the generic idea of data clippers (returning large volumes of high resolution scientific data from distant targets packed in memory chips) and possible exploitation of asteroid resources. Possible orbits were estimated by orbit calculations assuming circular and coplanar orbits for planets. Some particular challenge areas requiring further research work and related to some more ambitious mission scenarios are also identified and discussed.

The electric solar wind sail (E-sail) is an advanced concept for spacecraft propulsion, based on momentum transfer from the solar wind plasma stream, intercepted by long and charged tethers. The electrostatic field created by the tethers deflects trajectories of solar wind protons so that their flow-aligned momentum component decreases. The flow-aligned momentum lost by the protons is transferred to the charged tether by a Coulomb force (the charged tether is pulled by the plasma charge separation electric field) and then transmitted to the spacecraft as thrust. The concept is attractive for applications because no propellant is needed for traveling over long distances. The E-sail’s operating principle is different from other propellantless propulsion technologies such as the solar photon sail and the solar wind magnetic sail. The former is based on momentum transfer from sunlight (solar photons), while the latter is based on a large loop-shaped superconductive wire whose magnetic field deflects solar wind protons from their originally straight trajectories.


The main purpose of this article is to analyze the potential of E-sail technology in some of the envisaged possible applications for solar system space activities. To a limited extent we also adopt a comparative approach,estimating the added value and other advantages stemming from E-sail technology in comparison with present chemical and electric propulsion systems and(in some cases) with other propellantless propulsion concepts. When making such comparisons a key quantity that we use for representing the mission cost is the total required velocity change, Av, also called delta-v.The Sail Propulsion Working Group, a joint working group between the Navigation Guidance and Control Section and the Electric Propulsion Section of the European Space Agency, has envisaged the study of three reference missions which could be successfully carried out using propellantless propulsion concepts.


Even more advanced solar electric space sail configurations were explored in several previous electric sail papers.

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NASA: Ocean on Saturn Moon Could be as Salty as the Dead Sea

NASA: Ocean on Saturn Moon Could be as Salty as the Dead Sea | Amazing Science | Scoop.it

Scientists analyzing data from NASA’s Cassini mission have firm evidence the ocean inside Saturn's largest moon, Titan, might be as salty as Earth's Dead Sea.


The new results come from a study of gravity and topography data collected during Cassini's repeated flybys of Titan during the past 10 years. Using the Cassini data, researchers presented a model structure for Titan, resulting in an improved understanding of the structure of the moon's outer ice shell. The findings are published in this week’s edition of the journal Icarus.


"Titan continues to prove itself as an endlessly fascinating world, and with our long-lived Cassini spacecraft, we’re unlocking new mysteries as fast as we solve old ones," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, who was not involved in the study.


Additional findings support previous indications the moon's icy shell is rigid and in the process of freezing solid. Researchers found that a relatively high density was required for Titan's ocean in order to explain the gravity data. This indicates the ocean is probably an extremely salty brine of water mixed with dissolved salts likely composed of sulfur, sodium and potassium. The density indicated for this brine would give the ocean a salt content roughly equal to the saltiest bodies of water on Earth.


"This is an extremely salty ocean by Earth standards," said the paper's lead author, Giuseppe Mitri of the University of Nantes in France. "Knowing this may change the way we view this ocean as a possible abode for present-day life, but conditions might have been very different there in the past."


Cassini data also indicate the thickness of Titan's ice crust varies slightly from place to place. The researchers said this can best be explained if the moon's outer shell is stiff, as would be the case if the ocean were slowly crystalizing and turning to ice. Otherwise, the moon's shape would tend to even itself out over time, like warm candle wax. This freezing process would have important implications for the habitability of Titan's ocean, as it would limit the ability of materials to exchange between the surface and the ocean.


A further consequence of a rigid ice shell, according to the study, is any outgassing of methane into Titan's atmosphere must happen at scattered "hot spots" -- like the hot spot on Earth that gave rise to the Hawaiian Island chain. Titan's methane does not appear to result from convection or plate tectonics recycling its ice shell.


How methane gets into the moon's atmosphere has long been of great interest to researchers, as molecules of this gas are broken apart by sunlight on short geological timescales. Titan's present atmosphere contains about five percent methane. This means some process, thought to be geological in nature, must be replenishing the gas. The study indicates that whatever process is responsible, the restoration of Titan's methane is localized and intermittent.


"Our work suggests looking for signs of methane outgassing will be difficult with Cassini, and may require a future mission that can find localized methane sources," said Jonathan Lunine, a scientist on the Cassini mission at Cornell University, Ithaca, New York, and one of the paper's co-authors. "As on Mars, this is a challenging task."

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Supercomputers reveal strange, stress-induced transformations in world's thinnest materials

Supercomputers reveal strange, stress-induced transformations in world's thinnest materials | Amazing Science | Scoop.it

Interested in an ultra-fast, unbreakable, and flexible smart phone that recharges in a matter of seconds? Monolayer materials may make it possible. These atom-thin sheets—including the famed super material graphene—feature exceptional and untapped mechanical and electronic properties. But to fully exploit these atomically tailored wonder materials, scientists must pry free the secrets of how and why they bend and break under stress.

Fortunately, researchers have now pinpointed the breaking mechanism of several monolayer materials hundreds of times stronger than steel with exotic properties that could revolutionize everything from armor to electronics. A Columbia University team used supercomputers at the U.S. Department of Energy's Brookhaven National Laboratory to simulate and probe quantum mechanical processes that would be extremely difficult to explore experimentally.


They discovered that straining the materials induced a novel phase transition—a restructuring in their near-perfect crystalline structures that leads to instability and failure. Surprisingly, the phenomenon persisted across several different materials with disparate electronic properties, suggesting that monolayers may have intrinsic instabilities to be either overcome or exploited. The results were published in the journal Physical Review B.


"Our calculations exposed these monolayer materials' fundamental shifts in structure and character when stressed," said study coauthor and Columbia University Ph.D. candidate Eric Isaacs. "To see the beautiful patterns exhibited by these materials at their breaking points for the first time was enormously exciting—and important for future applications."

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Crystal structure of one of the most complex ternary complexes in cell division, important to cancer

Crystal structure of one of the most complex ternary complexes in cell division, important to cancer | Amazing Science | Scoop.it

Research carried out at the ICR has revealed the structure of one of the most important and complicated proteins in cell division – a fundamental process the development of cancer, published in Nature.


Images of the gigantic protein in unprecedented detail will transform scientists’ understanding of exactly how cells copy their chromosomes and divide, and could reveal binding sites for future cancer drugs.


A team from The Institute of Cancer Research, London, and the Medical Research Council Laboratory of Molecular Biology in Cambridge produced the first detailed images of the anaphase-promoting complex (APC/C).


The APC/C performs a wide range of vital tasks associated with mitosis, the process during which a cell copies its chromosomes and pulls them apart into two separate cells. Mitosis is used in cell division by all animals and plants.


Discovering its structure could ultimately lead to new treatments for cancer, which hijacks the normal process of cell division to make thousands of copies of harmful cancer cells.


In the study, which was funded by Cancer Research UK, the researchers reconstituted human APC/C and used a combination of electron microscopy and imaging software to visualize it at a resolution of less than a nanometer.


The resolution was so fine that it allowed the researchers to see the secondary structure – the set of basic building blocks which combine to form every protein. Alpha-helix rods and folded beta-sheet constructions were clearly visible within the 20 subunits of the APC/C, defining the overall architecture of the complex.


Previous studies led by the same research team had shown a globular structure for APC/C in much lower resolution, but the secondary structure had not previously been mapped. The new study could identify binding sites for potential cancer drugs.


Each of the APC/C’s subunits bond and mesh with other units at different points in the cell cycle, allowing it to control a range of mitotic processes including the initiation of DNA replication, the segregation of chromosomes along protein ‘rails’ called spindles, and the ultimate splitting of one cell into two, called cytokinesis. Disrupting each of these processes could selectively kill cancer cells or prevent them from dividing.

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Cystic Fibrosis Might Actually Consist of Two Different Diseases

Cystic Fibrosis Might Actually Consist of Two Different Diseases | Amazing Science | Scoop.it

The sister disease affects the pancreas and other organs, while leaving the lungs alone.


Thick mucus that can drown the lungs of a child has long been the hallmark of cystic fibrosis. The hereditary disease affects 30,000 Americans, and patients die unless they receive treatment to clear their lungs. But new research suggests that this pulmonary view of cystic fibrosis is only half of the picture: a suite of symptoms associated with cystic fibrosis can also occur in patients who do not have lung disease at all, indicating that cystic fibrosis is really two diseases. This second version, it appears, causes pancreatitis.


"Cystic fibrosis has been evaluated and managed by pulmonary doctors focusing on the lung, but other important problems are never seen by the pulmonologist and nobody's put the pieces together," says David Whitcomb of the University of Pittsburgh, who studies disorders of the pancreas.


Cystic fibrosis results from mutations in a gene that produces a tube-shaped protein known as CFTR, essential to the balance of electrolytes in the body. Specifically, this protein allows chloride ions to pass in and out of cells. When it malfunctions in classic cystic fibrosis, cells in the airway cannot produce normal mucus but instead make a thicker, stickier substance that clogs the lungs.


But CFTR leads a double life. Whitcomb's team screened a group of nearly 1,000 patients with pancreatitis and found nine abnormal but supposedly harmless versions of the CFTR gene. Their study suggests that the seemingly benign mutations break the switch that turns CFTR from a chloride portal to a channel for bicarbonate, a chemical that the pancreas produces to neutralize stomach acid. Patients with these mutations do not have the problems associated with the chloride channel, but the faulty bicarbonate channel means that they can suffer from painful pancreatitis, as well as sinusitis and, in men, infertility. Computer simulations confirmed that the mutations are all in places that would inhibit bicarbonate but not chloride from passing through.

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First time transplantation of inhibitory neuron progenitor cells reverses memory loss in Alzheimer's disease model

First time transplantation of inhibitory neuron progenitor cells reverses memory loss in Alzheimer's disease model | Amazing Science | Scoop.it
A new study has revealed a way to alleviate the learning and memory deficits caused by apoE4, the most important genetic risk factor for Alzheimer's disease, improving cognition to normal levels in aged mice. The success of the treatment in older mice, which corresponded to late adulthood in humans, is particularly important, as this would be the age that would be targeted were this method ever to be used therapeutically in people.


In the study, which was conducted in collaboration with researchers at UC San Francisco and published today in the Journal of Neuroscience, scientists transplanted inhibitory neuron progenitors -- early-stage brain cells that have the capacity to develop into mature inhibitory neurons -- into two mouse models of Alzheimer's disease, apoE4 or apoE4 with accumulation of amyloid beta, another major contributor to Alzheimer's. The transplants helped to replenish the brain by replacing cells lost due to apoE4, regulating brain activity and improving learning and memory abilities.


"This is the first time transplantation of inhibitory neuron progenitors has been used in aged Alzheimer's disease models," said first author Leslie Tong, a graduate student at the Gladstone Institutes and UCSF. "Working with older animals can be challenging from a technical standpoint, and it was amazing to see that the cells not only survived but affected activity and behavior."


The success of the treatment in older mice, which corresponded to late adulthood in humans, is particularly important, as this would be the age that would be targeted were this method ever to be used therapeutically in people.


"This is a very important proof of concept study," said senior author Yadong Huang, MD, PhD, an associate investigator at Gladstone Institutes and associate professor of neurology and pathology at UCSF. "The fact that we see a functional integration of these cells into the hippocampal circuitry and a complete rescue of learning and memory deficits in an aged model of Alzheimer's disease is very exciting."

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A noble gas cage: New material traps gases from nuclear fuel better

A noble gas cage: New material traps gases from nuclear fuel better | Amazing Science | Scoop.it

When nuclear fuel gets recycled, the process releases radioactive krypton and xenon gases. Naturally occurring uranium in rock contaminates basements with the related gas radon. A new porous material called CC3 effectively traps these gases, and research appearing July 20 in Nature Materials shows how: by breathing enough to let the gases in but not out.

The CC3 material could be helpful in removing unwanted or hazardous radioactive elements from nuclear fuel or air in buildings and also in recycling useful elements from the nuclear fuel cycle. CC3 is much more selective in trapping these gases compared to other experimental materials. Also, CC3 will likely use less energy to recover elements than conventional treatments, according to the authors.


The team made up of scientists at the University of Liverpool in the U.K., the Department of Energy's Pacific Northwest National Laboratory, Newcastle University in the U.K., and Aix-Marseille Universite in France performed simulations and laboratory experiments to determine how—and how well—CC3 might separate these gases from exhaust or waste.

"Xenon, krypton and radon are noble gases, which are chemically inert. That makes it difficult to find materials that can trap them," said coauthor Praveen Thallapally of PNNL. "So we were happily surprised at how easily CC3 removed them from the gas stream."


Noble gases are rare in the atmosphere but some such as radon come in radioactive forms and can contribute to cancer. Others such as xenon are useful industrial gases in commercial lighting, medical imaging and anesthesia.


The conventional way to remove xenon from the air or recover it from nuclear fuel involves cooling the air far below where water freezes. Such cryogenic separations are energy intensive and expensive. Researchers have been exploring materials called metal-organic frameworks, also known as MOFs, that could potentially trap xenon and krypton without having to use cryogenics. Although a leading MOF could remove xenon at very low concentrations and at ambient temperatures admirably, researchers wanted to find a material that performed better.

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Intestinal bacterial ecosystem: Identification of 741 bacteria, 181 new species, and 848 bacterial viruses

Intestinal bacterial ecosystem: Identification of 741 bacteria, 181 new species, and 848 bacterial viruses | Amazing Science | Scoop.it

Researchers at DTU (Technical University of Denmark) in collaboration with an international team from countries including France and China devised a method based on the co-abundance principle to easily identify the genomes (or genetic material) of unknown intestinal microorganisms. The scientists demonstrated this method on 396 human stool samples and uncovered 741 microbial species of which 181 are proposed to be completely novel.  Unlike prior methods to identify bacterial species, the use of CAGs obviates the need for assembly as well the need for a database of reference genomes.


The new approach also identified 848 viruses that infect each bacterium (called bacteriophages). The balance of intestinal fauna affects human health as it is increasingly recognized disrupting such balance for example by use of antibiotics leads to disease states.  Therefore modulation of the bacterial composition by viral agents is an attractive means to restore the balance.  Moreover, the new insight makes possible the exploitation of viruses to attack specific bacteria, thereby adding another tool to our pharmacological arsenal which is under increasing pressure from antibiotic resistance.


The human intestine is home to many microorganisms, whose cell population is estimated to be 10 times greater than the number of human cells in an individual.  Only a few species that can be cultivated in the laboratory to be sequenced by traditional methods.  Identification of the different microbial species in the intestinal ecology and their interactions will lead to better understanding of relevant disease conditions such as type 2 diabetes, asthma and obesity.

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DIXDC1 gene discovered that inhibits spread of deadly lung cancer

DIXDC1 gene discovered that inhibits spread of deadly lung cancer | Amazing Science | Scoop.it
A gene responsible for stopping the movement of cancer from the lungs to other parts of the body has been discovered by researchers, indicating a new way to fight one of the world’s deadliest cancers. By identifying the cause of this metastasis, which often happens quickly in lung cancer and results in a bleak survival rate, scientists are able to explain why some tumors are more prone to spreading than others. The newly discovered pathway may also help researchers understand and treat the spread of melanoma and cervical cancers.


Lung cancer, which also affects nonsmokers, is the leading cause of cancer-related deaths in the country (estimated to be nearly 160,000 this year). The United States spends more than $12 billion on lung cancer treatments, according to the National Cancer Institute. Nevertheless, the survival rate for lung cancer is dismal: 80 percent of patients die within five years of diagnosis largely due to the disease's aggressive tendency to spread throughout the body.


To become mobile, cancer cells override cellular machinery that typically keeps cells rooted within their respective locations. Deviously, cancer can switch on and off molecular anchors protruding from the cell membrane (called focal adhesion complexes), preparing the cell for migration. This allows cancer cells to begin the processes to traverse the body through the bloodstream and take up residence in new organs.


In addition to different cancers being able to manipulate these anchors, it was also known that about a fifth of lung cancer cases are missing an anti-cancer gene called LKB1 (also known as STK11). Cancers missing LKB1 are often aggressive, rapidly spreading through the body. However, no one knew how LKB1 and focal adhesions were connected.


Now, the Salk team has found the connection and a new target for therapy: a little-known gene called DIXDC1. The researchers discovered that DIXDC1 receives instructions from LKB1 to go to focal adhesions and change their size and number.


When DIXDC1 is "turned on," half a dozen or so focal adhesions grow large and sticky, anchoring cells to their spot. When DIXDC1 is blocked or inactivated, focal adhesions become small and numerous, resulting in hundreds of small "hands" that pull the cell forward in response to extracellular cues. That increased tendency to be mobile aids in the escape from, for example, the lungs and allows tumor cells to survive travel through the bloodstream and dock at organs throughout the body.


"The communication between LKB1 and DIXDC1 is responsible for a 'stay-put' signal in cells," says first author and Ph.D. graduate student Jonathan Goodwin. "DIXDC1, which no one knew much about, turns out to be inhibited in cancer and metastasis."


Tumors, Shaw and collaborators found in the new research, have two ways to turn off this "stay-put" signal. One is by inhibiting DIXDC1 directly. The other way is by deleting LKB1, which then never sends the signal to DIXDC1 to move to the focal adhesions to anchor the cell. Given this, the scientists wondered if reactivating DIXDC1 could halt a cancer's metastasis. The team took metastatic cells, which had low levels of DIXDC1, and overexpressed the gene. The addition of DIXDC1 did indeed blunt the ability of these cells to be metastatic in vitro and in vivo.


"It was very, very surprising that this gene would be so powerful," says Goodwin. "At the start of this study, we had no idea DIXDC1 would be involved in metastasis. There are dozens of proteins that LKB1 affects; for a single one to control so much of this phenotype was not expected."

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Nocturnal Moth Eyes Inspire More Efficient Photoelectrochemical Cells

Nocturnal Moth Eyes Inspire More Efficient Photoelectrochemical Cells | Amazing Science | Scoop.it

Collecting light with artificial moth eyes


All over the world researchers are investigating solar cells which imitate plant photosynthesis, using sunlight and water to create synthetic fuels such as hydrogen. Empa researchers have developed such a photoelectrochemical cell, recreating a moth’s eye to drastically increase its light collecting efficiency. The cell is made of cheap raw materials – iron and tungsten oxide. Rust – iron oxide – could revolutionise solar cell technology. This usually unwanted substance can be used to make photoelectrodes which split water and generate hydrogen.  Sunlight is thereby directly converted into valuable fuel rather than first being used to generate electricity. Unfortunately, as a raw material iron oxide has its limitations. Although it is unbelievably cheap and absorbs light in exactly the wavelength region where the sun emits the most energy, it conducts electricity very poorly and must therefore be used in the form of an extremely thin film in order for the water splitting technique to work. The disadvantage of this is that these thin-films absorb too little of the sunlight shining on the cell.


Empa researchers Florent Boudoire and Artur Braun have now succeeded in solving this problem. A special microstructure on the photoelectrode surface literally gathers in sunlight and does not let it out again. The basis for this innovative structure are tiny particles of tungsten oxide which, because of their saturated yellow colour, can also be used for photoelectrodes. The yellow microspheres are applied to an electrode and then covered with an extremely thin nanoscale layer of iron oxide. When external light falls on the particle it is internally reflected back and forth, till finally all the light is absorbed. All the entire energy in the beam is now available to use for splitting the water molecules.


In principle the newly conceived microstructure functions like the eye of a moth, explains Florent Boudoire. The eyes of these night active creatures need to collect as much light as possible to see in the dark, and also must reflect as little as possible to avoid detection and being eaten by their enemies. The microstructure of their eyes especially adapted to the appropriate wavelength of light. Empa's photocells take advantage of the same effect.


In order to recreate artificial moth eyes from metal oxide microspheres, Florent Boudoire sprays a sheet of glass with a suspension of plastic particles, each of which contains at its centre a drop of tungsten salt solution. The particles lie on the glass like a layer of marbles packed close to each other. The sheet is placed in an oven and heated, the plastic material burns away and each drop of salt solution is transformed into the required tungsten oxide microsphere. The next step is to spray the new structure with an iron salt solution and once again heat it in an oven.


Reference:
Florent Boudoire, Rita Toth, Jakob Heier, Artur Braun, Edwin C. Constable, Photonic light trapping in self-organized all-oxide microspheroids impacts photoelectrochemical water splitting, Energy & Environmental Sciences, in press.

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Extending Moore's Law: Shrinking transistor size for smaller, more efficient computers

Extending Moore's Law: Shrinking transistor size for smaller, more efficient computers | Amazing Science | Scoop.it
Over the years, computer chips have gotten smaller thanks to advances in materials science and manufacturing technologies. This march of progress, the doubling of transistors on a microprocessor roughly every two years, is called Moore's Law. But there's one component of the chip-making process in need of an overhaul if Moore's law is to continue: the chemical mixture called photoresist. In a bid to continue decreasing transistor size while increasing computation and energy efficiency, chip-maker Intel has partnered with researchers to design an entirely new kind of resist.


Now, in a bid to continue decreasing transistor size while increasing computation and energy efficiency, chip-maker Intel has partnered with researchers from the U.S. Department of Energy's Lawrence Berkeley National Lab (Berkeley Lab) to design an entirely new kind of resist. And importantly, they have done so by characterizing the chemistry of photoresist, crucial to further improve performance in a systematic way. The researchers believe their results could be easily incorporated by companies that make resist, and find their way into manufacturing lines as early as 2017.


The new resist effectively combines the material properties of two pre-existing kinds of resist, achieving the characteristics needed to make smaller features for microprocessors, which include better light sensitivity and mechanical stability, says Paul Ashby, staff scientist at Berkeley Lab's Molecular Foundry, a DOE Office of Science user facility. "We discovered that mixing chemical groups, including cross linkers and a particular type of ester, could improve the resist's performance." The work is published this week in the journal Nanotechnology.


To understand why resist is so important, consider a simplified explanation of how your microprocessors are made. A silicon wafer, about a foot in diameter, is cleaned and coated with a layer of photoresist. Next ultraviolet light is used to project an image of the desired circuit pattern including components such as wires and transistors on the wafer, chemically altering the resist.


Depending on the type of resist, light either makes it more or less soluble, so when the wafer is immersed in a solvent, the exposed or unexposed areas wash away. The resist protects the material that makes up transistors and wires from being etched away and can allow the material to be selectively deposited. This process of exposure, rinse and etch or deposition is repeated many times until all the components of a chip have been created.


The problem with today's resist, however, is that it was originally developed for light sources that emit so-called deep ultraviolet light with wavelengths of 248 and 193 nanometers. But to gain finer features on chips, the industry intends to switch to a new light source with a shorter wavelength of just 13.5 nanometers. Called extreme ultraviolet (EUV), this light source has already found its way into manufacturing pilot lines. Unfortunately, today's photoresist isn't yet ready for high volume manufacturing.


"The semiconductor industry wants to go to smaller and smaller features," explains Ashby. While extreme ultraviolet light is a promising technology, he adds, "you also need the resist materials that can pattern to the resolution that extreme ultraviolet can promise." So teams led by Ashby and Olynick, which include Berkeley Lab postdoctoral researcher Prashant Kulshreshtha, investigated two types of resist. One is called crosslinking, composed of molecules that form bonds when exposed to ultraviolet light. This kind of resist has good mechanical stability and doesn't distort during development -- that is, tall, thin lines made with it don't collapse. But if this is achieved with excessive crosslinking, it requires long, expensive exposures. The second kind of resist is highly sensitive, yet doesn't have the mechanical stability.

When the researchers combined these two types of resist in various concentrations, they found they were able to retain the best properties of both. The materials were tested using the unique EUV patterning capabilities at the CXRO. Using the Nanofabrication and Imaging and Manipulation facilities at the Molecular Foundry to analyze the patterns, the researchers saw improvements in the smoothness of lines created by the photoresist, even as they shrunk the width. Through chemical analysis, they were also able to see how various concentrations of additives affected the cross-linking mechanism and resulting stability and sensitivity.

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Russ Roberts's curator insight, July 18, 11:50 PM

Thanks to Dr. Stefan Gruenwald for this fascinating story about extending Moore's law through advances in material science.  The key to shrinking microchips and, thereby, computers, is manipulating ultraviolet light and a chemical mixture called photoresist.  Recent research in reducing the size of computer chips is providing some success in developing resists capable of using different wavelengths of light.  New photoresist technology should hit the marketplace by 2017.  Aloha de Russ (KH6JRM).

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Untangling spider's webs: Largest-ever genomic study shows orb weaver spiders do not share common origins

Untangling spider's webs: Largest-ever genomic study shows orb weaver spiders do not share common origins | Amazing Science | Scoop.it
The largest-ever phylogenetic study of spiders shows that, contrary to long-held popular opinion, the two groups of spiders that weave orb-shaped webs do not share a single origin.


The largest-ever phylogenetic study of spiders, conducted by postdoctoral student Rosa Fernández, Gonzalo Giribet, Alexander Agassiz Professor of Zoology, and Gustavo Hormiga, a professor at George Washington University, shows that, contrary to long-held popular opinion, the two groups of spiders that weave orb-shaped webs do not share a single origin. The study is described in a July 17 paper published in Current Biology.


"This study examines two different groups of orb-weaver spiders, as well as several other species," Giribet said. "Using thousands of genes, we did a comparative phylogenetic analysis, and what we now know is there is not a single origin for the orb-weaver spiders.


"There are two possible explanations for this," he continued. "One is that the orb web evolved far back in the lineage of the two groups, but has been lost in some groups. The other option is that the orb web evolved independently in these two groups. We still haven't resolved that question yet -- we need to sample many more of these intermediate groups before we can say which option is correct."


The belief that orb-weaver spiders shared a common origin, Giribet said, came largely from earlier morphological studies. Even as new genetic tools became more commonplace in the last two decades, the single origin theory held sway, in part, because early phylogenetic studies relied on just a handful of genes to draw a picture of the spider evolutionary tree.


"Some early analyses pointed out that spiders with orb webs didn't form a group -- they appeared in different places along the tree," Giribet said. "But the genes that were being used weren't enough to elucidate the evolution of a very diverse group like spiders, so most people dismissed many of those results."


In recent years, however, sequencing technology has dropped dramatically in cost, meaning researchers who once were able to study only a handful of genes can now examine the entire genome of a particular organism.


"The technology has changed what we are able to do in terms of the questions we can ask and the questions we can answer," Giribet continued. "Even just five years ago, we were spending thousands of dollars to sequence 3,000 genes. Today, we're spending just a few hundreds of dollars to sequence millions, which is almost an entire genome. In the case of Giribet and Fernández, the technology allowed them to sequence genes from 14 different spiders, creating the largest genomic data set for the study of spiders.


"This paper is at the forefront of how these large data sets are being analyzed, and how we are now constructing phylogenies using molecular data," Giribet said. "We can now test all possible pitfalls of phylogenetic interference to make sure our results are as accurate as possible."

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Quantum bounce could make black holes explode

Quantum bounce could make black holes explode | Amazing Science | Scoop.it
If space-time is granular, it could reverse gravitational collapse and turn it into expansion.


Black holes might end their lives by transforming into their exact opposite — 'white holes' that explosively pour all the material they ever swallowed into space, say two physicists. The suggestion, based on a speculative quantum theory of gravity, could solve a long-standing conundrum about whether black holes destroy information.


The theory suggests that the transition from black hole to white hole would take place right after the initial formation of the black hole, but because gravity dilates time, outside observers would see the black hole lasting billions or trillions of years or more, depending on its size. If the authors are correct, tiny black holes that formed during the very early history of the Universe would now be ready to pop off like firecrackers and might be detected as high-energy cosmic rays or other radiation. In fact, they say, their work could imply that some of the dramatic flares commonly considered to be supernova explosions could in fact be the dying throes of tiny black holes that formed shortly after the Big Bang.


Albert Einstein’s general theory of relativity predicts that when a dying star collapses under its own weight, it can reach a stage at which the collapse is irreversible and no known force of nature can stop it. This is the formation of a black hole: a spherical surface, known as the event horizon, appears, shrouding the star inside from outside observers while it continues to collapse, because nothing — not even light or any other sort of information — can escape the event horizon.


Because dense matter curves space, ‘classical’ general relativity predicts that the star inside will continue to shrink into what is known as a singularity, a region where matter is infinitely dense and space is infinitely curved. In such situations, the known laws of physics cease to be useful.


Many physicists, however, believe that at some stage in this process, quantum-gravity effects should take over, arresting the collapse and avoiding the infinities.



Via Mariaschnee
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