Effective control of invasive weeds can help attempts at reforestation in Panama

Saccharum spontaneum is an invasive grass that has spread extensively in disturbed areas throughout the Panama Canal watershed, where it has created a fire hazard and inhibited reforestation efforts. The weed originally believed to be originally from India, is perfectly adapted to the conditions in Panama and produces excessive amounts of biomass during the wet season, which impedes reforestation efforts. A new study published in the open access journal Neo Biotaproposes an effective method for controlling the growth, based on analysis of its reproductive biology. Currently physical removal of above ground biomass is the primary means of controlling the weed, which is largely ineffective and does little to inhibit spread of the species. This is due to the insufficient knowledge about reproduction of the species and this is where science comes to the rescue.

A team of scientists from Australia and Panama provide a detailed examination of a series of studies looking at some of the basic reproductive mechanisms and strategies utilised by S. spontaneum to provide information to support development of better targeted management strategies.

It turns out that S. spontaneum has a very good survival toolkit being able to reproduce through buds on stems that had been dried for up to six weeks. Separate experiments showed that even leftover stem fragments could sprout when left on the surface or buried shallowly and that larger pieces sprouted more readily than smaller pieces.

Ar-Raniry Islamic University

Ar-Raniry Islamic University

 The study shows that the through better knowledge the panacea of a big problem can turn out to be very simple. A good timing of management actions to prevent flowering would significantly reduce the seed load into the environment and help to prevent spread to new sites. Similarly simple but effective would be cutting stems into smaller pieces allowing them to dry out and reduce the ability of buds to sprout.

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Critical protein discovered for healthy cell growth in mammals

A team of researchers from Penn State University and the University of California has discovered a protein that is required for the growth of tiny, but critical, hair-like structures called cilia on cell surfaces. The discovery has important implications for human health because lack of cilia can lead to serious diseases such as polycystic kidney disease, blindness and neurological disorders. "If we want to better understand and treat diseases related to cilium development, we need to identify important regulators of cilium growth and learn how those regulators function," said co-author Aimin Liu, associate professor of biology at Penn State. "This work gives us significant insight into one of the earliest steps in cilium formation."

Ar- Raniry Islamic University

The researchers describe their findings in a paper that will be published online in the Proceedings of the National Academy of Sciences during the week of 27 January 2014. In addition to Liu, authors include Penn State cellular biologists Xuan Ye, Huiqing Zeng and Gang Ning, as well as Jeremy F. Reiter, a biophysicist at the University of California -- San Francisco.

Cilia, which are present on the surface of almost all mammalian cells, are responsible for sending, receiving, and processing information within the body. "You could think of cilia as the cells' antennae," Liu said. "Without cilia, the cells can't sense what's going on around them, and they can't communicate." Cilia also perform important filtering and cleansing functions. For example, cilia inside the trachea, or windpipe, trap and prevent bacteria from entering the lungs.

In a previous study, Liu and his colleagues learned that a protein called C2cd3 is important for cilium formation because mice that lacked this protein exhibited severe developmental problems typically associated with the lack of cilia. "At the time we knew only that if we get rid of the protein, the cells in the animal would not grow cilia," Liu said. "We didn't understand why, but now we do."

A cilium grows from a centriole, a structure that clings to the inner surface of the cell and serves as an anchor for the cilium. Before a cell can grow a cilium, it needs to assemble a set of appendages at one end of the centriole. These appendages can then connect the centriole to the cell surface, allowing the outgrowth of a cilium. Just how these appendages are assembled, though, remained a mystery for more than four decades since their discovery in 1962. Liu and his colleagues found that appendages were not assembled at the end of the centriole when the C2cd3 protein is not present. As a result, the centriole is not associated with the cell membrane and cannot recruit other proteins for the further growth of the cilium. "So our protein is required for the very first step of putting a cilium together," Liu explained. "Without those appendages, the cilium growth cannot happen."

The researchers hope their discovery will lead to greater knowledge of the process of cilium development and, eventually, to treatments for a wide range of health problems that fall under the label of ciliopathy. "Ciliopathy is a scientific term that covers a lot of diseases," Liu said. As well as contributing to cystic disorders in the kidney and liver, lack of cilia can lead to blindness or deafness, since cilia in the retina serve as receptors that process light stimulation and cilia within the ear are required in neurons that translate sound waves into neural signals.

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Getting a charge from changes in humidity

A new type of electrical generator uses bacterial spores to harness the untapped power of evaporating water, according to research conducted at the Wyss Institute of Biologically Inspired Engineering at Harvard University. Its developers foresee electrical generators driven by changes in humidity from sun-warmed ponds and harbors. The prototype generators work by harnessing the movement of a sheet of rubber coated on one side with spores. The sheet bends when it dries out, much as a pine cone opens as it dries or a freshly fallen leaf curls, and then straightens when humidity rises. Such bending back and forth means that spore-coated sheets or tiny planks can act as actuators that drive movement, and that movement can be harvested to generate electricity.

 

"If this technology is developed fully, it has a very promising endgame," said Ozgur Sahin, Ph.D., who led the study, first at Harvard's Rowland Institute, later at the Wyss Institute, and most recently at Columbia University, where he's now an associate professor of biological sciences and physics. Sahin collaborated with Wyss Institute Core Faculty member L. Mahadevan, Ph.D., who is also the Lola England de Valpine professor of applied mathematics, organismic and evolutionary biology, and physics at the School of Engineering and Applied Sciences at Harvard University, and Adam Driks,Ph.D., a professor of microbiology and immunology at Loyola University Chicago Stritch School of Medicine. The researchers reported their work yesterday in Nature Nanotechnology.

Water evaporation is the largest power source in nature, Sahin said. "Sunlight hits the ocean, heats it up, and energy has to leave the ocean through evaporation," he explained. "If you think about all the ice on top of Mt. Everest -- who took this huge amount of material up there? There's energy in evaporation, but it's so subtle we don't see it."

But until now no one has tapped that energy to generate electricity.

As Sahin pursued the idea of a new humidity-driven generator, he realized that Mahadevan had been investigating similar problems from a physical perspective. Specifically, he had characterized how moisture deforms materials, including biological materials such as pinecones, leaves and flowers, as well as human-made materials such as a sheet of tissue paper lying in a dish of water.

Sahin collaborated with Mahadevan and Driks on one of those studies. A soil bacterium called Bacillus subtilis wrinkles as it dries out like a grape becoming a raisin, forming a tough, dormant spore. The results, which they reported in 2012 in the Journal of the Royal Society Interface, explained why.

Unlike raisins, which cannot re-form into grapes, spores can take on water and almost immediately restore themselves to their original shape. Sahin realized that since they shrink reversibly, they had to be storing energy. In fact, spores would be particularly good at storing energy because they are rigid, yet still expand and contract a great deal, the researchers predicted.

"Since changing moisture levels deform these spores, it followed that devices containing these materials should be able to move in response to changing humidity levels," Mahadevan said. "Now Ozgur has shown very nicely how this could be used practically."

When Sahin first set out to measure the energy of spores, he was taken by surprise.

He put a solution thick with spores on a tiny, flexible silicon plank, expecting to measure the humidity-driven force in a customized atomic force microscope. But before he could insert the plank, he saw it curving and straightening with his naked eye. His inhaling and exhaling had changed the humidity subtly, and the spores had responded.

"I realized then that this was extremely powerful," Sahin said.

In fact, simply increasing the humidity from that of a dry, sunny day to a humid, misty one enabled the flexible, spore-coated plank to generate 1000 times as much force as human muscle, and at least 10 times as much as other materials engineers currently use to build actuators, Sahin discovered. In fact, moistening a pound of dry spores would generate enough force to lift a car one meter off the ground.

To build such an actuator, Sahin tested how well spore-coated materials such as silicon, rubber, plastic, and adhesive tape stored energy, settling on rubber as the most promising material.

Then he built a simple humidity-driven generator out of Legos™, a miniature fan, a magnet and a spore-coated cantilever. As the cantilever flips back and forth in response to moisture, it drives a rotating magnet that produces electricity.

Sahin's prototype captures just a small percentage of the energy released by evaporation, but it could be improved by genetically engineering the spores to be stiffer and more elastic. Indeed, in early experiments, spores of a mutant strain provided by Driks stored twice as much energy as normal strains.

"Solar and wind energy fluctuate dramatically when the sun doesn't shine or the wind doesn't blow, and we have no good way of storing enough of it to supply the grid for long," said Wyss Institute Founding Director Don Ingber, M.D., Ph.D. "If changes in humidity could be harnessed to generate electricity night and day using a scaled up version of this new generator, it could provide the world with a desperately needed new source of renewable energy."

The work was funded by the U.S. Department of Energy, the Rowland Junior Fellows Program, and the Wyss Institute for Biologically Inspired Engineering at Harvard University. In addition to Sahin, Driks and Mahadevan, the authors included Xi Chen, a postdoctoral research associate at Columbia University.

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New genes spring and spread from non-coding DNA

"Where do new genes come from?" is a long-standing question in genetics and evolutionary biology. A new study from researchers at the University of California, Davis, published Jan. 23 in Science Express, shows that new genes are created from non-coding DNA more rapidly than expected. "This shows very clearly that genes are being born from ancestral sequences all the time," said David Begun, professor of evolution and ecology at UC Davis and senior author on the paper.

Geneticists have long puzzled about how completely new genes appear. In a well-known model proposed by Nobel laureate Susumu Ohno, new functions appear when existing genes are duplicated and then diverge in function. Begun's laboratory discovered a few years ago that new genes could also appear from previously non-coding stretches of DNA, and similar effects have since been discovered in other animals and plants.

"This is the first example of totally new genes still spreading through a species," said Li Zhao, a postdoctoral researcher at UC Davis and first author on the paper.

Zhao looked at RNA transcripts -- corresponding to expressed genes -- in the testes of several wild-derived strains of the fruit fly Drosophila melanogaster, and compared them to transcripts expressed in the standard reference sequence strain and in two closely related species. She found 248 new genes that exist only in D. melanogaster, just over a hundred of which were "fixed," or already spread throughout the population.

These genes emerged from ancestrally non-coding DNA since D. melanogaster split from its close relative, D. simulans.

The new genes showed evidence of being under selection, meaning that they were spreading through the population as flies carrying them gained an edge in reproduction. They fell into two broad classes: genes found at high frequency tended to be larger and more complex, and therefore likely had more significant functions, than those found at low frequency.

The researchers studied testis because earlier work showed a relatively high rate of adaptive evolution for male reproductive function, Begun said. They plan to expand their studies to other tissues.

Zhao said that it's possible that these new genes form when a random mutation in the regulatory machinery causes a piece of non-coding DNA to be transcribed to RNA.

"If it has a beneficial effect, then it gets selected," she said. It's difficult to say at this point how important this phenomenon is for generating new genetic material, Zhao said.

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Engineers teach old chemical new tricks to make cleaner fuels, fertilizers

University researchers from two continents have engineered an efficient and environmentally friendly catalyst for the production of molecular hydrogen (H2), a compound used extensively in modern industry to manufacture fertilizer and refine crude oil into gasoline. Although hydrogen is abundant element, it is generally not found as the pure gas H2 but is generally bound to oxygen in water (H2O) or to carbon in methane (CH4), the primary component in natural gas. At present, industrial hydrogen is produced from natural gas using a process that consumes a great deal of energy while also releasing carbon into the atmosphere, thus contributing to global carbon emissions.

In an article published Jan 26 in Nature Chemistry, nanotechnology experts from Stanford Engineering and from Denmark's Aarhus University explain how to liberate hydrogen from water on an industrial scale by using electrolysis.

In electrolysis, electrical current flows through a metallic electrode immersed in water. This electron flow induces a chemical reaction that breaks the bonds between hydrogen and oxygen atoms. The electrode serves as a catalyst, a material that can spur one reaction after another without ever being used up. Platinum is the best catalyst for electrolysis. If cost were no object, platinum might be used to produce hydrogen from water today.

But money matters. The world consumes about 55 billion kilograms of hydrogen per year. It now costs about $1 to $2 per kilogram to produce hydrogen from methane. So any competing process, even if it's greener, must hit that production cost, which rules out electrolysis based on platinum.

In their Nature Chemistry paper, the researchers describe how they re-engineered the atomic structure of a cheap and common industrial material to make it nearly as efficient at electrolysis as platinum -- a finding that has the potential to revolutionize industrial hydrogen production.

The project was conceived by Jakob Kibsgaard, a post-doctoral researcher with Thomas Jaramillo, an assistant professor of chemical engineering at Stanford. Kibsgaard started this project while working with Flemming Besenbacher, a professor at the Interdisciplinary Nanoscience Center (iNANO) at Aarhus.

Subhead: Meet Moly Sulfide

Since World War II petroleum engineers have used molybdenum sulfide -- moly sulfide for short -- to help refine oil.

Until now, however, this chemical was not considered a good catalyst for making moly sulfide to produce hydrogen from water through electrolysis. Eventually scientists and engineers came to understand why: the most commonly used moly sulfide materials had an unsuitable arrangement of atoms at their surface.

Typically, each sulfur atom on the surface of a moly sulfide crystal is bound to three molybdenum atoms underneath. For complex reasons involving the atomic bonding properties of hydrogen, that configuration isn't conducive to electrolysis.

In 2004, Stanford chemical engineering professor Jens Norskov, then at the Technical University of Denmark, made an important discovery. Around the edges of the crystal, some sulfur atoms are bound to just two molybdenum atoms. At these edge sites, which are characterized by double rather than triple bonds, moly sulfide was much more effective at forming H2.

Armed with that knowledge, Kibsgaard found a 30-year-old recipe for making a form of moly sulfide with lots of these double-bonded sulfurs at the edge.

Using simple chemistry, he synthesized nanoclusters of this special moly sulfide. He deposited these nanoclusters onto a sheet of graphite, a material that conducts electricity. Together the graphite and moly sulfide formed a cheap electrode. It was meant to be a substitute for platinum, the ideal but expensive catalyst for electrolysis.

The question then became: could this composite electrode efficiently spur the chemical reaction that rearranges hydrogen and oxygen atoms in water?

As Jaramillo put it: "Chemistry is all about where electrons want to go, and catalysis is about getting those electrons to move to make and break chemical bonds."

Subhead: The acid test

So the experimenters put their system to the acid test -- literally.

They immersed their composite electrode into water that was slightly acidified, meaning it contained positively charged hydrogen ions. These positive ions were attracted to the moly sulfide clusters. Their double-bonded shape gave them just the right atomic characteristic to pass electrons from the graphite conductor up to the positive ions. This electron transfer turned the positive ions into neutral molecular hydrogen, which bubbled up and away as a gas.

Most importantly, the experimenters found that their cheap, moly sulfide catalyst had the potential to liberate hydrogen from water on something approaching the efficiency of a system based on prohibitively expensive platinum.

Subhead: Yes, but does it scale?

But in chemical engineering, success in a beaker is only the beginning.

The larger questions were: could this technology scale to the 55 billion kilograms per year global demand for hydrogen, and at what finished cost per kilogram?

Last year, Jaramillo and a dozen co-authors studied four factory-scale production schemes in an article for The Royal Society of Chemistry's journal of Energy and Environmental Science.

They concluded that it could be feasible to produce hydrogen in factory-scale electrolysis facilities at costs ranging from $1.60 and $10.40 (Rp.20.000 - Rp.123.000) per kilogram -- competitive at the low end with current practices based on methane -- though some of their assumptions were based on new plant designs and materials.

"There are many pieces of the puzzle still needed to make this work, and much effort ahead to realize them," Jaramillo said. "However, we can get huge returns by moving from carbon-intensive resources to renewable, sustainable technologies to produce the chemicals we need for food and energy."

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World's first magma-enhanced geothermal system created in Iceland

In 2009, a borehole drilled at Krafla, northeast Iceland, as part of the Icelandic Deep Drilling Project (IDDP), unexpectedly penetrated into magma (molten rock) at only 2100 meters depth, with a temperature of 900-1000 C. The borehole, IDDP-1, was the first in a series of wells being drilled by the IDDP in Iceland in the search for high-temperature geothermal resources. The January 2014 issue of the international journal Geothermics is dedicated to scientific and engineering results arising from that unusual occurrence. This issue is edited by Wilfred Elders, a professor emeritus of geology at the University of California, Riverside, who also co-authored three of the research papers in the special issue with Icelandic colleagues.

"Drilling into magma is a very rare occurrence anywhere in the world and this is only the second known instance, the first one, in 2007, being in Hawaii," Elders said. "The IDDP, in cooperation with Iceland's National Power Company, the operator of the Krafla geothermal power plant, decided to investigate the hole further and bear part of the substantial costs involved."

Accordingly, a steel casing, perforated in the bottom section closest to the magma, was cemented into the well. The hole was then allowed to heat slowly and eventually allowed to flow superheated steam for the next two years, until July 2012, when it was closed down in order to replace some of the surface equipment.

"In the future, the success of this drilling and research project could lead to a revolution in the energy efficiency of high-temperature geothermal areas worldwide," Elders said.

He added that several important milestones were achieved in this project: despite some difficulties, the project was able to drill down into the molten magma and control it; it was possible to set steel casing in the bottom of the hole; allowing the hole to blow superheated, high-pressure steam for months at temperatures exceeding 450 C, created a world record for geothermal heat (this well was the hottest in the world and one of the most powerful); steam from the IDDP-1 well could be fed directly into the existing power plant at Krafla; and the IDDP-1 demonstrated that a high-enthalpy geothermal system could be successfully utilized.

"Essentially, the IDDP-1 created the world's first magma-enhanced geothermal system," Elders said. "This unique engineered geothermal system is the world's first to supply heat directly from a molten magma."

Elders explained that in various parts of the world so-called enhanced or engineered geothermal systems are being created by pumping cold water into hot dry rocks at 4-5 kilometers depths. The heated water is pumped up again as hot water or steam from production wells. In recent decades, considerable effort has been invested in Europe, Australia, the United States, and Japan, with uneven, and typically poor, results.

"Although the IDDP-1 hole had to be shut in, the aim now is to repair the well or to drill a new similar hole," Elders said. "The experiment at Krafla suffered various setbacks that tried personnel and equipment throughout. However, the process itself was very instructive, and, apart from scientific articles published in Geothermics, comprehensive reports on practical lessons learned are nearing completion."

The IDDP is a collaboration of three energy companies -- HS Energy Ltd., National Power Company and Reykjavik Energy -- and a government agency, the National Energy Authority of Iceland. It will drill the next borehole, IDDP-2, in southwest Iceland at Reykjanes in 2014-2015. From the onset, international collaboration has been important to the project, and in particular a consortium of U.S. scientists, coordinated by Elders, has been very active, authoring several research papers in the special issue of Geothermics.

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Humans can use smell to detect levels of dietary fat

New research from the Monell Center reveals humans can use the sense of smell to detect dietary fat in food. As food smell almost always is detected before taste, the findings identify one of the first sensory qualities that signals whether a food contains fat. Innovative methods using odor to make low-fat foods more palatable could someday aid public health efforts to reduce dietary fat intake. "The human sense of smell is far better at guiding us through our everyday lives than we give it credit for," said senior author Johan Lundström, PhD, a cognitive neuroscientist at Monell. "That we have the ability to detect and discriminate minute differences in the fat content of our food suggests that this ability must have had considerable evolutionary importance."

As the most calorically dense nutrient, fat has been a desired energy source across much of human evolution. As such, it would have been advantageous to be able to detect sources of fat in food, just as sweet taste is thought to signal a source of carbohydrate energy.

Although scientists know that humans use sensory cues to detect fat, it still remains unclear which sensory systems contribute to this ability. The Monell researchers reasoned that fat detection via smell would have the advantage of identifying food sources from a distance.

While previous research had determined that humans could use the sense of smell to detect high levels of pure fat in the form of fatty acids, it was not known whether it was possible to detect fat in a more realistic setting, such as food.

In the current study, reported in the open access journal PLOS ONE, the researchers asked whether people could detect and differentiate the amount of fat in a commonly consumed food product, milk.

To do this, they asked healthy subjects to smell milk containing an amount of fat that might be encountered in a typical milk product: either 0.125 percent, 1.4 percent or 2.7 percent fat.

The milk samples were presented to blindfolded subjects in three vials. Two of the vials contained milk with the same percent of fat, while the third contained milk with a different fat concentration. The subjects' task was to smell the three vials and identify which of the samples was different.

The same experiment was conducted three times using different sets of subjects. The first used healthy normal-weight people from the Philadelphia area. The second experiment repeated the first study in a different cultural setting, the Wageningen area of the Netherlands. The third study, also conducted in Philadelphia, examined olfactory fat detection both in normal-weight and overweight subjects.

In all three experiments, participants could use the sense of smell to discriminate different levels of fat in the milk. This ability did not differ in the two cultures tested, even though people in the Netherlands on average consume more milk on a daily basis than do Americans. There also was no relation between weight status and the ability to discriminate fat.

"We now need to identify the odor molecules that allow people to detect and differentiate differentiate levels of fat. Fat molecules typically are not airborne, meaning that they are unlikely to be sensed by sniffing food samples," said lead author Sanne Boesveldt, PhD, a sensory neuroscientist. "We will need sophisticated chemical analyses to sniff out the signal."

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Staying cool in the nanoelectric universe by getting hot

As smartphones, tablets and other gadgets become smaller and more sophisticated, the heat they generate while in use increases. This is a growing problem because it can cause the electronics inside the gadgets to fail. Conventional wisdom suggests the solution is to keep the guts of these gadgets cool. But a new University at Buffalo research paper hints at the opposite: that is, to make laptops and other portable electronic devices more robust, more heat might be the answer. "We've found that it's possible to protect nanoelectronic devices from the heat they generate in a way that preserves how these devices function," said Jonathan Bird, UB professor of electrical engineering. "This will hopefully allow us to continue developing more powerful smartphones, tablets and other devices without having a fundamental meltdown in their operation due to overheating."

 The paper, "Formation of a protected sub-band for conduction in quantum point contacts under extreme biasing," was published Jan. 19 in the journal Nature Nanotechnology. Bird is the co-lead author along with Jong Han, UB associate professor of physics. Contributing authors are Jebum Lee and Jungwoo Song, both recently earned PhDs at UB; Shiran Xiao, PhD candidate at UB; and John L. Reno, Center for Integrated Nanotechnologies at Sandia National Laboratories.

Heat in electronic devices is generated by the movement of electrons through transistors, resistors and other elements of an electrical network. Depending on the network, there are a variety of ways, such as cooling fans and heat sinks, to prevent the circuits from overheating.

But as more integrated circuits and transistors are added to devices to boost their computing power, it's becoming more difficult to keep those elements cool. Most research centers on developing advanced materials that are capable of withstanding the extreme environment inside smartphones, laptops and other devices.

While advanced materials show tremendous potential, the UB research suggests there may still be room within the existing paradigm of electronic devices to continue developing more powerful computers.

To achieve their findings, the researchers fabricated nanoscale semiconductor devices in a state-of-the-art gallium arsenide crystal provided to UB by Sandia's Reno. The researchers then subjected the chip to a large voltage, squeezing an electrical current through the nanoconductors. This, in turn, increased the amount of heat circulating through the chip's nano transistor.

But instead of degrading the device, the nanotransistor spontaneously transformed itself into a quantum state which was protected from the effect of heating and provided a robust channel of electric current. To help explain, Bird offered an analogy to Niagara Falls. "The water, or energy, comes from a source; in this case, the Great Lakes. It's channeled into a narrow point (the Niagara River) and ultimately flows over Niagara Falls. At the bottom of waterfall is dissipated energy. But unlike the waterfall, this dissipated energy recirculates throughout the chip and changes how heat affects, or in this case doesn't affect, the network's operation."

While this behavior may seem unusual, especially conceptualizing it in terms of water flowing over a waterfall, it is the direct result of the quantum mechanical nature of electronics when viewed on the nanoscale. The current is made up of electrons which spontaneously organize to form a narrow conducting filament through the nanoconductor. It is this filament that is so robust against the effects of heating.

"We're not actually eliminating the heat, but we've managed to stop it from affecting the electrical network. In a way, this is an optimization of the current paradigm," said Han, who developed the theoretical models which explain the findings.

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Milky Way May Have Formed 'Inside-Out:' Gaia Provides New Insight Into Galactic Evolution

 A breakthrough using data from the Gaia-ESO project has provided evidence backing up theoretically predicted divisions in the chemical composition of the stars that make up the Milky Way's disc -- the vast collection of giant gas clouds and billions of stars that give our Galaxy its 'flying saucer' shape.

By tracking the fast-produced elements, specifically magnesium in this study, astronomers can determine how rapidly different parts of the Milky Way were formed. The research suggests that stars in the inner regions of the Galactic disc were the first to form, supporting ideas that our Galaxy grew from the inside-out.

The team has shown that older, ‘metal-poor’ stars inside the Solar Circle – the orbit of our Sun around the centre of the Milky Way, which takes roughly 250 million years to complete – are far more likely to have high levels of magnesium. The higher level of the element inside the Solar Circle suggests this area contained more stars that “lived fast and die young” in the past. (Credit: University of Cambridge)

 Using data from the 8-m VLT in Chile, one of the world's largest telescopes, an international team of astronomers took detailed observations of stars with a wide range of ages and locations in the Galactic disc to accurately determine their 'metallicity': the amount of chemical elements in a star other than hydrogen and helium, the two elements most stars are made from.

Immediately after the Big Bang, the Universe consisted almost entirely of hydrogen and helium, with levels of "contaminant metals" growing over time. Consequently, older stars have fewer elements in their make-up -- so have lower metallicity.

"The different chemical elements of which stars -- and we -- are made are created at different rates -- some in massive stars which live fast and die young, and others in sun-like stars with more sedate multi-billion-year lifetimes," said Professor Gerry Gilmore, lead investigator on the Gaia-ESO Project.

Massive stars, which have short lives and die as 'core-collapse supernovae', produce huge amounts of magnesium during their explosive death throes. This catastrophic event can form a neutron star or a black hole, and even trigger the formation of new stars.

The team have shown that older, 'metal-poor' stars inside the Solar Circle -- the orbit of our Sun around the centre of the Milky Way, which takes roughly 250 million years to complete -- are far more likely to have high levels of magnesium. The higher level of the element inside the Solar Circle suggests this area contained more stars that "lived fast and die young" in the past.

The stars that lie in the outer regions of the Galactic disc -- outside the Solar Circle -- are predominantly younger, both 'metal-rich' and 'metal-poor', and have surprisingly low magnesium levels compared to their metallicity.

This discovery signifies important differences in stellar evolution across the Milky Way disc, with very efficient and short star formation timescales occurring inside the Solar Circle; whereas, outside the Sun's orbit, star formation took much longer.

"We have been able to shed new light on the timescale of chemical enrichment across the Milky Way disc, showing that outer regions of the disc take a much longer time to form," said Maria Bergemann from Cambridge's Institute of Astronomy, who led the study.

"This supports theoretical models for the formation of disc galaxies in the context of Cold Dark Matter cosmology, which predict that galaxy discs grow inside-out."

The findings offer new insights into the assembly history of our Galaxy, and are the part of the first wave of new observations from the Gaia-ESO survey, the ground-based extension to the Gaia space mission -- launched by the European Space Agency at the end of last year -- and the first large-scale survey conducted on one the world's largest telescopes: the 8-m VLT in Paranal, Chile.

The study is published online today through the astronomical database Astro-ph, and has been submitted to the journal Astronomy and Astrophysics.

The new research also sheds further light on another much debated "double structure" in the Milky Way's disc -- the so-called 'thin' and 'thick' discs.

"The thin disc hosts spiral arms, young stars, giant molecular clouds -- all objects which are young, at least in the context of the Galaxy," explains Aldo Serenelli from the Institute of Space Sciences (Barcelona), a co-author of the study. "But astronomers have long suspected there is another disc, which is thicker, shorter and older. This thick disc hosts many old stars that have low metallicity."

During the latest research, the team found that:

• Stars in the young, 'thin' disc aged between 0 -- 8 billion years all have a similar degree of metallicity, regardless of age in that range, with many of them considered 'metal-rich'.
• There is a "steep decline" in metallicity for stars aged over 9 billion years, typical of the 'thick' disc, with no detectable 'metal-rich' stars found at all over this age.
• But stars of different ages and metallicity can be found in both discs.

"From what we now know, the Galaxy is not an 'either-or' system. You can find stars of different ages and metal content everywhere!" said Bergemann. "There is no clear separation between the thin and thick disc. The proportion of stars with different properties is not the same in both discs -- that's how we know these two discs probably exist -- but they could have very different origins."

Added Gilmore: "This study provides exciting new evidence that the inner parts of the Milky Way's thick disc formed much more rapidly than did the thin disc stars, which dominate near our Solar neighbourhood."

With upcoming releases of Gaia-ESO, an even better handle on the age-metallicity relation and the structure of the Galactic disc is expected, say the team. In a couple of years, these data will be complemented by positions and kinematics provided by the Gaia satellite and together will revolutionise the field of Galactic astronomy.

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Cinta dan Waktu

Alkisah di suatu pulau, tinggallah berbagai macam benda-benda abstrak, ada cinta, kesedihan, kekayaan, kegembiraan dan sebagainya. Mereka hidup berdampingan dengan baik.

Akan tetapi, suatu ketika datanglah bencana badai yang menghempaskan pulau itu. Air laut tiba-tiba naik dan menenggelamkan pulau tersebut. Semua penghuni mencoba menyelamatkan dirinya. Cinta terlihat kebingungan karena ia tidak dapat berenang dan tidak mempunyai perahu. Ia berdiri di tepi pantai mencoba mencari pertolongan. Sementara itu air makin meninggi membasahi kaki Cinta.

Tak lama kemudian Cinta melihat kekayaan sedang mengayuh perahu. "Wahai kekayaan, Kekayaan, Tolonglah aku!" teriak Cinta.

"Aduh, maaf Cinta, perahuku telah penuh dengan harta bendaku. Aku tidak dapat membawamu ikut serta, nanti perahu ini bisa karam," jawab kekayaan.

Kemudian kekayaan mengayuh perahunya cepat-cepat pergi. Cinta sangat sedih sekali melihatnya. Lalu ia melihat Kegembiraan lewat dengan perahunya dan Cinta pun meminta tolong padanya. Akan tetapi, Kegembiraan terlalu gembira sehingga tidak dapat mendengarkan terikan Cinta.

Air pun makin tinggi membasahi Cinta sampai ke pinggang. Cinta semakin panik. Tak lama kemudian lewatlah Kecantikan. "Kecantikan, bawalah aku bersamamu!", teriak Cinta.

"Aduh, Cinta. Maaf, kamu basah dan kotor. Aku tidak bisa membawamu ikut. Nanti kamu mengotori perahuku yang sangat indah dan aku banggakan ini." sahut Kecantikan.

Cinta pun sangat sedih mendengarnya. Ia mulai menangis terisak-isak. Saat itulahsedang lewat Kesedihan. "Oh, syukur dirimu lewat, Kesedihan. Bawalah aku dalam perahumu," kata Cinta.

"Maaf, Cinta. Aku sedang bersedih dan sedang ingin sendirian saja." kata Kesedihan dengan pilu. Cinta putus asa. Ia merasakan air makin naik dan akan menenggelamkannya. Pada saat genting itulah tiba-tiba terdengar suara, "Wahai, Cinta! Ayo naik ke perahuku!"

Cinta menoleh mencari arah suara itu dan ia hanya melihat perahu dan orang tua di dalamnya. Cepat-cepat Cinta naik ke perahu tersebut, tepat sebelum air menenggelamkannya.

Akhirnya, sampailah di pulau terdekat dan orang tua itu menurunkan Cinta dan segera pergi lagi. Pada saat itulah Cinta tersadar bahwa ia sama sekali tidak mengetahui siapa gerangan orang tua baik hati tadi. Tidak lama, Cinta menanyakan hal tersebut kepada seorang penduduk di pulau itu. "Oh. orang tua itu adalah Sang Waktu." kata orang itu.

"Tetapi, mengapa ia menolongku, Bahkan aku tidak mengenalnya. Teman-teman terdekatku pun malah tidak menolongku." ungkap Cinta heran.

"sebab," kata orang itu, "hanya Waktulah yang tahu seberapa nilai sesungguhnya dari Cinta itu..."

Penulis Ust. Adi Abdillah

Surat Dari Tuhan

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Harga Putus Asa

Pada suatu saat, iblis membuat iklan bahwasanya ia akan mengobral alat-alat kerjanya. Kemudian tiba saatnya di hari H, seluruh alatnya dipajang untuk dilihat calon pembeli dan lengkap dengan harga jualnya. Bayangkan seperti halnya kita masuk ke supermarket, barang yang dijual sangat menarik dan tiap barang sangat berguna sesuai fungsinya. Harga pun tidak mahal.

Alat yang dijual antara lain dengki, iri, tidak jujur, tidak menghargai orang lain, tidak tahu terimakasih, malas, dendam, dan masih banyak lagi.

Di pojok display terdapat satu alat yang bentuknya sederhana, sudah agak usang, tetapi harganya sangat tinggi sekali, bahkan jauh melampaui harga-harga lainnya.

Hal ini memancing rasa penasaran salah satu calon pembeli, "Apa nama alat itu, kok mahal sekali padahal sudah sangat usang".

Iblis pun menjawab, "Iya, memang. Alat ini mudah dipakai dan berdaya guna tinggi. saya bisa masuk dengan mudah ke dalam hati manusia menggunakan alat ini jika dibandingkan dengan alat lainnya. Begitu saya berhasil masuk ke dalam hati manusia, maka saya mudah melakukan apa saja yang saya inginkan. Barang ini menjadi sangat usang karena saya sangat sering menggunakannya kepada hampir setiap manusia. Sebagian besar manusia tidak mengetahui, bahwa alat putus asa ini adalah kepunyaan saya."

Penulis Ust. Adi Abdillah

Surat Dari Tuhan

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Surat Dari Tuhan

 Saat kau bangun di pagi hari, Aku memandangmu, Berharap, kau akan berbicara kepada-Ku. Meski hanya sepatah kata untuk minta pendapat-Ku atau sekedar bersyukur kepada-Ku atas sesuatu hal yang indah yang terjadi dalam hidupmu hari ini dan kemarin.

Namun, Aku melihatmu begitu sibuk mempersiapkan diri untuk pergi bekerja. Aku kembali menanti dirimu saat engkau sedang bersiap. Aku tahu, akan ada sedikit waktu bagimu untuk berhenti dan menyapa-Ku. Akan tetapi, ternyata engkau terlalu sibuk.

Di suatu tempat, engkau duduk di sebuah kursi selama lima belas menit tanpa melakukan apa pun. Kemudian Aku melihat engkau menggerakkan kakimu. Aku berpikir engkau akan berbicara kepada-Ku, tetapi engkau berlari ke telepon dan menelepon seseorang untuk mendengarkan berita terbaru. Aku melihatmu ketika engkau pergi bekerja dan Aku menanti dengan sabar sepanjang hari. Dengan semua kegiatanmu, Aku berpikir engkau terlalu sibuk mengucapkan sesuatu kepada-Ku.

Sebelum makan siang, Aku melihatmu memandang ke sekeliling. Mungkin engkau merasa malu untuk berbicara kepada-Ku. Itulah sebabnya mengapa engkau tidak menundukkan kepalamu. Engkau memandang tiga atau empat meja sekitarmu dan melihat bebrapa temanmu berbicara dan menyebut nama-Ku dengan lembut sebelum mereka menyantap rezeki yang Aku berikan. Akan tetapi, enhkau tidak melakukannya. Bagi-Ku tidak apa-apa, masih ada waktu tersisa dan Aku berharap engkau akan berbicara kepada-Ku. Saat engkau pulang ke rumah, kelihatannya masih banyak hal yang harus engkau kerjakan. Lalu setelah tugasmu selesai, engkau pun menyalakan TV dan banyak menghabiskan waktu untuk menontonnya. Kembali, Aku menanti dengan sabar. Begitu juga saat engkau menikmati makananmu, engkau lupa tidak berbicara kepada-Ku.

Saat engkau tidur, Aku berpikir kau merasa terlalu lelah. Setelah mengucapkan selamat malam kepada keluargamu, engkau melompat ketempat tidur dan tertidur tanpa sepatah katapun nama-Ku engkau sebut. Tidak apa-apa, karena engkau tidak menyadari bahwa Aku selalu hadir untukmu. Aku telah bersabar lebih lama dari yang pernah engkau sadari. Aku bahkan ingin menyadari bagaimana bersabar terhadap orang lain. Aku sangat menyayangimu. Setiap hari Aku menantikan sepatah kata, do'a, pikiran atau ucapan syukur dari hatimu. Baiklah, engkau bangun kembali dan kembali Aku menanti dengan penuh kasih bahwa hari ini engkau akan memberiku sedikit waktu untuk menyapa-Ku.

Aku sendiri bertanya-tanya, apakah salah-Ku kepadamu ? Rezeki yang Aku limpahkan, kesehatan yang Aku berikan, harta yang Aku relakan, makanan yang Aku hidangkan, atau anak-anak yang Aku rahmatkan ? Apakah hal itu tidak membuatmu ingat kepada-Ku ?

Percayalah, Aku selalu mengasihimu dan aku tetap berharap suatu saat engkau akan menyapa-Ku, memohon perlindungan-Ku, dan bersujud menghadap-Ku.

Allah Sang Pencipta

Penulis Ust. Adi Abdillah

Buku Surat Dari Tuhan

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Cekungan Air Tanah Sumatera

PENDAHULUAN

Pemanfaatan air tanah di Pulau (P.) Sumatera menunjukkan kecenderungan yang terus meningkat seiring dengan pesatnya pembangunan di berbagai sektor, baik sebagai sumber pasokan air bersih penduduk maupun industri, serta pertanian dan peternakan. Kemajuan pembangunan yang cukup mencolok berlangsung terutama di ibukota provinsi.

Berkaitan dengan hal itu, pengelolaan air tanah secara bijaksana perlu dilakukan secara lebih dini agar pemanfaatannya dapat terus berlanjut untuk generasi sekarang dan mendatang. Dalam hal ini, Undang-Undang Nomor 7 Tahun 2004 tentang Sumber Daya Air, Pasal 12 ayat (2), telah menetapkan kebijakan pengelolaan air tanah yang dilandasi oleh satuan wilayah cekungan air tanah dengan pemahaman bahwa air tanah merupakan sumber daya alam yang ketersediaannya, mencakup kuantitas dan kualitas, sangat tergantung pada kondisi lingkungan cekungan air tanah dan terbentuk melalui proses pengimbuhan, pengaliran, dan pelepasannya.

Keberadaan cekungan air tanah tidak dibatasi oleh batas administratif suatu daerah, artinya suatu cekungan air tanah dapat berada pada satu wilayah kabupaten/kota, lintas batas kabupaten/kota, lintas batas provinsi, atau bahkan lintas batas negara.

Berkaitan dengan hal tersebut di atas, Direktorat Tata Lingkungan Geologi dan Kawasan Pertambangan (DTLGKP), salah satu unit kerja pada Direktorat Jenderal Geologi dan Sumber Daya Mineral, Departemen Energi dan Sumber Daya Mineral yang membidangi air tanah, telah melakukan identifikasi sebaran dan potensi ketersediaan air tanah yang terkandung dalam cekungan air tanah di wilayah P. Sumatera. Informasi sebaran dan potensi ketersediaan air tanah serta batas wilayah administrasi wilayah yang dituangkan dalam Peta Cekungan Air Tanah P. Sumatera Skala 1 :250.000, digunakan sebagai acuan dalam perencanaan pengelolaan air tanah pada setiap cekungan air tanah di wilayah itu.

METODOLOGI

Metode    identifikasi    cekungan air    tanah dalam pekerjaan ini mencakup pengumpulan data hasil penyelidikan yang pernah dilakukan di daerah ini (data sekunder) seperti data/informasi geologi, hidrogeologi, dan data terkait lainnya. Data primer sebagai hasil pengujian terpilih diperoleh melalui pengukuran dan pengamatan langsung di lapangan terhadap aspek geologi dan hidrogeologi yang dipandang penting untuk melengkapi data sekunder tersebut.

Evaluasi dan analisis data dilakukan dengan berbagai cara pendekatan, seperti estimasi kuantitatif dan deduktif. Analisis secara deduktif dilakukan di beberapa daerah yang memiliki data/informasi kurang memadai namun memiliki karakteristik geologi/ hidrogeologi yang relatif sama dengan daerah terdekat lainnya yang memiliki data/ informasi lebih lengkap.

Penentuan batas cekungan air tanah dilakukan dengan menggunakan tipe-tipe batas yang didasarkan sifat hidraulik air tanah sebagai berikut :

• Batas tanpa aliran (zero-flow or noflow boundaries) merupakan tipe batas, pada batas tersebut tidak terjadi aliran air tanah atau besarnya aliran air tanah tidak berarti jika dibandingkan dengan aliran pada akuifer utama. Contoh dari tipe batas ini adalah kontak secara lateral maupun vertikal antara akuifer dengan batuan yang secara nisbi bersifat kedap air. Termasuk tipe batas ini adalah batas pemisah air tanah (groundwater divide), yakni batas yang memisahkan dua aliran air tanah dengan arah berlawanan.
• Batas muka air permukaan (head-controlled boundaries), apabila pada batas tersebut diketahui tekanan hidrauliknya, dapat bersifat muka air tetap atau berubah terhadap waktu.
• Batas aliran air tanah (flow-controlled boundaries), apabila pada batas tersebut volume air tanah per satuan waktu yang masuk atau keluar cekungan air tanah berasal dari atau menuju ke lapisan batuan yang tidak diketahui tekanan hidrauliknya dan keterusannya.
• Batas muka air tanah bebas (free surface boundary), apabila pada batas tersebut tekanannya sama dengan tekanan udara luar.

KEADAAN UMUM

Wilayah P. Sumatera mencakup seluruh wilayah administrasi Provinsi (Prov.) Nanggroe Aceh Darrussalam, Prov. Sumatera Utara, Prov. Riau, Prov. Kepulauan Riau, Prov. Sumatera Barat, Prov. Jambi, Prov. Bengkulu, Prov. Sumatera Selatan, Prov. Lampung, dan Prov. Kepulauan Bangka Belitung. Secara geografis wilayah tersebut terletak di antara garis 95000’-107001’ Bujur Timur dan garis 5040’ Lintang Utara – 6o06’ Lintang Selatan, dengan luas mencapai sekitar 449.600 Km2. 

Curah hujan rata-rata tahunan tertinggi di P. Sumatera berkisar antara 2.500 dan 4.000 mm yang berlangsung di sepanjang daerah Bukit Barisan dan sekitarnya, sedangkan curah hujan terendahberlangsung di bagian timur P. Sumatera terutama pada daerah bergelombang sampai datar dengan kisaran curah hujan antara 2.000 dan 3.000 mm.

Secara keseluruhan, bulan kering di daerah ini berlangsung antara Juli hingga Oktober dengan curah hujan rata-rata bulanan berkisar antara 25-100 mm, sedangkan bulan basah terjadi pada Desember hingga Maret dengan kisaran curah hujan rata-rata bulanan antara 200 dan 500 mm.

Tektonik di daerah ini berlangsung sejak zaman Pratersier yang diikuti dengan pembentukan struktur geologi berupa lipatan (fold) dan sesar (fault), misalnya Sesar Semangko, yang memotong daerah sepanjang P. Sumatera, cekungan sedimentasi, daerah tinggian, dan kegiatan volkanik. Struktur geologi dan lapisan batuan tersebut memiliki peran penting dalam tataan hidrogeologi pulau ini. 

Secara umum, sebaran kelompok batuan penyusun P. Sumatera dapat dikemukakan sebagai berikut :

• Pulau Sumatera Bagian Tengah-Timur

Morfologi P. Sumatera bagian tengah hingga ke pantai timurnya merupakan daerah relatif datar sampai bergelombang yang umumnya dibentuk oleh endapan aluvium sungai, endapan rawa, dan sedimen berumur Kuarter. Setempat-setempat terdapat berbagai jenis batuan berumur Kuarter Tua, Tersier dan Pratersier yang membentuk medan perbukitan bergelombang.  

• Pulau Sumatera Bagian Tengah-Barat

Morfologi P. Sumatera bagian tengah hingga ke pantai baratnya merupakan daerah perbukitan sampai bergelombang yang membentuk deretan gunung api Bukit Barisan yang disusun oleh batuan volkanik berupa breksi, lava, batuan piroklastik bersifat agak padu sampai padu, berumur Tersier hingga Kuarter. Setempat dijumpai batuan terobosan dan batuan sedimen pratersier yang sebagian telah terubah menjadi batuan malihan.

 Distribusi dan keberadaan cekungan air tanah berdasarkan wilayah administrasinya adalah sebagai berikut ini :

Informasi yang disajikan pada tingkat diketahui, hanyalah merupakan gambaran umum potensi ketersediaan air tanah dalam cekungan, mengingat penghitungannya didasarkan atas data geologi, hidrogeologi, serta data terkait yang bersifat umum tanpa dilakukan penyelidikan dan pengujian lapangan secara langsung. 

Secara umum, daerah dengan potensi ketersediaan air tanah relatif tinggi dapat dijumpai pada bagian kaki kerucut gunung api (stato volcano). Potensi air tanah tinggi sampai sedang di daerah dataran, umumnya terdapat di daerah yang dibentuk oleh bahan rombakan batuan gunung api yang berbatasan langsung dengan kerucut gunung api, dan juga daerah yang dibentuk oleh F. Jularayeu, F. Seurela, F. Kerumutan dan F. Minas. 

Pemanfaatan air tanah secara intensif terutama di kota-kota besar (ibukota provinsi) seperti Banda Aceh, Medan, Padang, dan Pekanbaru cenderung meningkat, terutama untuk keperluan industri dan pasokan air bersih penduduk. Pemanfaatan air tanah tersebut, jika tanpa memperhitungkan potensi cekungan air tanah dikhawatirkan akan mengganggu kelestarian ketersediannya.

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