But to sustain that high growth rate into the next decade, the industry will have to start tapping offshore wind resources, creating a need for wind turbines that are larger, lower-maintenance, and deliver more power with less weight.
To support research in this area, the U.S. Department of Energy has awarded $7.5 million to six projects, each aiming to develop advanced drivetrains for wind turbines up to 10 megawatts in size. Five of the projects use direct-drive, or gearless, drivetrain technology to increase reliability, and at least two use superconductivity technologies for increased efficiencies and lower weight.
Current designs can't be scaled up economically. Most of the more than 25,000 wind turbines deployed across the United States have a power rating of three megawatts or less and contain complex gearbox systems. The gearboxes match the slow speed of the turbine rotor (between 15 to 20 rotations per minute) to the 2,000 rotations per minute required by their generators. Higher speeds allow for more compact and less expensive generators, but conventional gearboxes—a complex interaction of wheels and bearings—need regular maintenance and are prone to failure, especially at higher speeds.
On land, where turbines are more accessible, gearbox maintenance issues can be tolerated. In rugged offshore environments, the cost of renting a barge and sending crews out to fix or maintain a wind-ravaged machine can be prohibitive. "A gearbox that isn't there is the most reliable gearbox," says Fort Felker, direct of the National Renewable Energy Laboratory's wind technology center.
To increase reliability and reduce maintenance costs, a number of companies—among them Enercon and Siemens of Germany, France's Alstom and China's Goldwind Global—have developed direct-drive or "gearless" drivetrains. In such a setup, the rotor shaft is attached directly to the generator, and they both turn at the same speed. But this introduces a new challenge: increased weight.
To achieve the power output of a comparable gearbox-based system, a direct-drive system must have a larger internal diameter that increases the radius—and therefore the speed—at which its magnets rotate around coils to generate current. This also means greater reliance on increasingly costly rare-earth metals used to make permanent magnets.
Kiruba Haran, manager of the electric machines lab at GE Global Research, one recipient of the DOE funding, says direct-drive systems get disproportionately heavier as their power rating increases. A four-megawatt generator might weight 85 tons, but at eight megawatts, it would approach 200 tons.
GE believes it can develop an eight-megawatt generator that weights only 50 tons by adapting the superconducting electromagnets used in magnetic resonance imaging. Unlike a permanent magnet, an electromagnet creates a magnetic field when an electric current is applied to it. When made from coils of superconducting wire, it has no electrical resistance, making it more efficient, with the caveat that it must be cooled to minus 250 °C. The approach would eliminate the need for rare-earth materials, assuming GE can lower the cost enough to make it commercially viable.
Florida-based Advanced Magnet Lab, which also received DOE funding, believes it can build a 10-megawatt generator that weighs just 70 tons. As with GE's technology, the core of the company's innovation is a superconducting direct-drive generator. The company has developed a compact coil design based on double-helix windings that can carry high currents and handle the immense magnetic forces produced in the system.
Advanced Magnet Lab president Mark Senti says the high cost of superconducting materials and of cryogenically cooling makes no sense for today's three-megawatt wind turbines. But beyond six megawatts, he argues, the systems become competitive with conventional generator designs. At 10 megawatts, "it gives you the highest power-per-weight ratio."
There's also significant room for advancement. Senti says most superconducting wiring costs $400 per meter today, but new materials made out of inexpensive magnesium and boron powders promise to lower costs substantially. With improvements in manufacturing and less expensive cooling techniques, Senti figures superconducting technology could eventually become economical for wind turbines as small as two megawatts, making it ideal for both onshore and offshore markets.
Superconductivity isn't in everyone's plans. One of the other funding recipients, Boulder Wind Power, is focused on designing a better stator—stationary coil—for direct drive systems. Instead of copper wiring wound around a heavy iron core, the company's stator is made of printed circuit boards. These lightweight components can be manufactured in high volume and assembled in modules, making them easier to repair in remote offshore locations. "With this design, you just send a couple of guys out there to remove a stator segment and literally plug in a new one," says Derek Pletch, vice president of turbine development at Boulder Wind.
NREL, meanwhile, is taking a hybrid approach by designing a medium-speed drivetrain that uses a simpler single-stage gearbox and a medium-sized generator. Felker says the approach can be easily adapted to existing designs and be picked up in the marketplace faster. Clipper Windpower and Dehlsen Associates also received funding. After six months, the DOE is expected to shortlist the designs and contribute an additional $2 million to each project for performance testing.
A new experiment looks at the shapes of healthy and cancerous cells taken from the human cervix and has attempted to quantify the geometrical differences between them. The research, carried out at Clarkson University in Potsdam, N.Y. finds that the cancerous cells show more fractal behavior than healthy cells.
Fractal is the name used for heavily indented curves or shapes that look very similar over a variety of size scales. For example, the edge of a snowflake, when observed with a microscope, has a lacelike structure that looks the same whether at the level of a millimeter, or a tenth of a millimeter, or even a thousandth of a millimeter. The position of galaxy clusters in the sky seems to be fractal. So does the snaking geometry of streams in a river valley, or the foliage of leaves on a tree. The shape of coastlines and clouds reveals a fractal, "self-similar" geometry. Even the "drip" paintings of Jackson Pollack are fractal.
Fractal geometry apparently also appears in the human body. The pattern of heartbeats over long intervals looks fractal. How about the geometry of cells? And could the observation of fractal geometry be used to identify cancer cells?
Igor Sokolov and his Clarkson colleagues used an atomic force microscope to view cells down to the level of one nanometer, or a billionth of a meter (one-millionth of a millimeter). Just as the needle on a record player rides over the groove of a rotating vinyl record to read out the music stored on the record's surface, so the sharp needle forming the heart of an atomic force microscope rides above a sample reading out the contours of matter just below at nearly atomic resolution.
Previous studies of cells at the microscopic level produced two-dimensional maps of the cells' surface. The new study produces not only three-dimensional surface maps of geometry. But with their atomic force microscope device the Clarkson scientists can also map properties such as the rigidity of the cells at various points on its surface or a cell's adhesion, its ability to cling to a nearby object, such as the needle probe of the atomic force microscope itself.
The Clarkson measurements show that cancerous cells feature a consistent fractal geometry, while healthy cells show some fractal properties but in an ambiguous way. The fact that the adhesive map is fractal for cancerous cells but not for healthy cells was not known before.
Being able to differentiate clearly between healthy and cancerous cells would be important step toward a definitive diagnosis of cancer. Can a fractal measurement of cells serve as such a test for malignancy?
Sokolov believes it can.
"The existing cytological screening tests for cervical cancer, like Pap smear, and liquid-based cytology, are effective and non-invasive, but are insufficiently accurate," said Sokolov.
These tests determine the presence of suspicious abnormal cells with sensitivity levels ranging from 80 percent all the way down to 30 percent, for an average of 47 percent.
The fractal criterion used in the Clarkson work was 100 percent accurate in identifying the cancerous nature of 300 cells derived from 12 human subjects, Sokolov said. He intends now to undertake a much wider test.
"We expect that the methodology based on our finding will substantially increase the accuracy of early non-invasive detection of cervical cancer using cytological tests," Sokolov said.
Sokolov asserts that physics-based methods, such as his atomic force microscope maps of cells, will complement or even exceed in detection ability the more traditional biochemical analysis carried out at the single cell level.
"We also plan to study how fractal behavior changes during cancerous transformation, when a normal cell turns into a fully developed malignant cell, one with a high degree of invasiveness and the ability to reproduce itself uncontrollably," Sokolov added.
Robert Austin, an expert on biological physics at Princeton University in N.J., believes it is important to learn more about the properties that make cancer cells lethal, such as their ability to metastasize, to invade new parts of the body. About the Clarkson paper, which is appearing in the journal Physical Review Letters, Austin said "Perhaps this is a step in the direction of connecting physical aspects of cancer cells with the biological reality that their proliferation and invasiveness is what makes them deadly."
Secondo i dati resi pubblici dall’ Organizzazione Mondiale della Sanità (Oms), infatti, è il posto più inquinato del mondo. La colpa è delle industrie e dell’uso massiccio di combustibili fossili per alimentare i trasporti. Ma nella lista nera dell’Oms figurano molte altre città del mondo arabo che, assieme ad alcuni stati africani e asiatici, è una delle aree del pianeta a soffrire maggiormente di inquinamento ambientale. La classifica è stata stilata monitorando la qualità dell’aria di circa 1100 città sparse in 91 paesi, tenute sotto controllo dal 2003 al 2009. Le misurazioni hanno interessato il cosiddetto particolato, cioè l’insieme delle particelle solide e liquide disperse nell’atmosfera con un diametro inferiore ai 10 micrometri (PM10) e ai 2,5 micrometri (PM2,5).
Ma veniamo ai numeri. Ahwaz si piazza al primo posto con una densità media di PM10 pari a 372 microgrammi per metro cubo all’anno. Una cifra mostruosa se pensiamo che il limite fissato dall’Oms per questo tipo di particelle è di 20 microgrammi per metro cubo. Segue la capitale della Mongolia con i suoi 279 microgrammi per metro cubo all’anno e Sanandaj, un’altra città dell’Iran con 254 microgrammi per metro cubo all’anno. Nei primi posti figurano anche il Pakistan, il Botswana e il Senegal, presenti nella top ten dei paesi più intossicati al mondo. E l’ Italia? Torino è la città più inquinata (47 microgrammi per metro cubo all’anno), ma anche Milano e Napoli non se la passano bene (44 microgrammi per metro cubo all’anno).
I maggiori responsabili di questo stato di cose, secondo l’Oms, sono l’ industrializzazione sfrenata e l’uso quasi esclusivo di combustibili fossili sia nei trasporti sia nella produzione di elettricità. E non è un caso che nelle prime posizioni della classifica figurino molti paesi emergenti, pronti a sacrificare l’ambiente (e la salute) in nome del progresso e della crescita economica. “ Le industrie emettono dense nuvole di fumo nell’aria e il governo non fa alcuno sforzo per controllare e frenare le loro attività”, si lamenta Mohammad Hasan, un cittadino di Karachi, in Pakistan. Va da sé che senza regolamentare il settore industriale, tutti i piccoli sforzi fatti per cercare di migliorare la qualità dell’aria (a Karachi, per esempio, i bus più inquinanti sono stati sostituiti con veicoli a basse emissioni) rischiano di essere vani.
A rimetterci sono le persone, sempre più a rischio di ammalarsi di tumore o malattie a carico dell’apparato respiratorio e cardio-circolatorio. I dati dell’Organizzazione mondiale della sanità parlano di circa 1,34 milioni di morti premature causate ogni anno dall’inquinamento. Un problema che non è solo etico, ma economico: investendo nella tutela dell’ambiente, infatti, i governi riuscirebbero a ridurre le spese sostenute per la sanità pubblica, recuperando fondi da investire altrove.
È quello che hanno fatto nazioni come l’Australia e il Canada (13 microgrammi per metro cubo all’anno), l’Irlanda (15 microgrammi per metro cubo all’anno) o la Norvegia (22 microgrammi per metro cubo all’anno), agli ultimi posti di questa sfortunata classifica proprio perché hanno scelto di investire sull’ambiente. Anche se, per essere sinceri, dobbiamo ricordare che a differenza di altri paesi godono di situazioni geografiche e demografiche (densità di popolazione bassissime) certamente più favorevoli.
Sempre a onor del vero, bisognerebbe poi ricordare che la classifica dell’OMS soffre di alcune imperfezioni. Per esempio, analizza un campione eterogeneo, dove ci sono pochissimi dati per paesi coma la Russia e la Cina, due delle nazioni più inquinate al mondo. Inoltre, le misurazioni effettuate fanno riferimento ad anni diversi. Ma è comunque un’analisi utile per disegnare questa infelice mappa globale, dove tutti dovrebbero preoccuparsi della salute del pianeta. Perché nel cielo non ci sono linee di confine e l’inquinamento viaggia facilmente da un paese all’altro.
Riferimenti: WHO - Via: wired.it - Credits immagine: Il Cairo di Nina Hale/Creative Commons/Flickr
Pentru prima dată, cercetătorii au detectat semnalele din creier care anticipează momentul în care un sofer va frâna. În viitor, sistemele de frânare asistată ale automobilelor ar putea frâna înainte ca soferul să facă un gest, prin simpla detectie a gândurilor acestuia.
Semnalele electrice trimise de creier pentru a semnaliza intentia de frânare au fost detectate de oamenii de stiintă cu 130 de milisecunde înainte ca soferii să apese pedala de frânare, au descoperit cercetătorii de la Universitatea Tehnică din Berlin. Dacă frâna ar fi fost aplicată în momentul în care gândul a fost detectat, distanta de frânare ar fi fost redusă cu 4 metri.
Studiul publicat în Journal of Natural Engineering a fost efectuat pe o serie de voluntari care au fost asezati în fata a trei monitoare, într-un simulator de conducere numit "The Open Source Racing Car Simulator".
Fiecare individ a fost rugat să conducă un vehicul la 18 metri în spatele unui alt autoturism condus de computer, care circula cu o viteză de aproximativ 100 de kilometri pe oră.
Simularea includea trafic din sens opus si curbe dificile. Când luminile de frână ale masinii din fată s-au aprins, subiectii au frânat si ei. Utilizând datele înregistrate de electroencefalograf (test electrofiziologic de explorare a sistemului nervos central) si electromiograf (test folosit pentru înregistrarea activitătii electrice a muschilor), cercetătorii au putut identifica semnale care au intervenit constant în timpul frânării de urgentă.
Următorul pas pe care cercetătorii ar vrea să îl facă ar fi acela de a utiliza electroencefalograful si electromiograful în situatii reale. Desi acest tel este foarte greu de atins, cercetarea ar constitui un prim pas spre crearea unui sistem de conducere asistată care să ia în considerare datele transmise de la creier.
A set of glasses packed with technology normally seen in smartphones and games consoles is the main draw at one of the featured stands at this year’s Royal Society Summer Science Exhibition.
But the exhibit isn’t about the latest gadget must-have, it’s all about aiding those with poor vision and giving them greater independence.
‘We want to be able to enhance vision in those who’ve lost it or who have little left or almost none,’ explains Dr Stephen Hicks of the Department of Clinical Neurology at Oxford University. ‘The glasses should allow people to be more independent – finding their own directions and signposts, and spotting warning signals,’ he says.
Technology developed for mobile phones and computer gaming – such as video cameras, position detectors, face recognition and tracking software, and depth sensors – is now readily and cheaply available. So Oxford researchers have been looking at ways that this technology can be combined into a normal-looking pair of glasses to help those who might have just a small area of vision left, have cloudy or blurry vision, or can’t process detailed images.
The glasses should be appropriate for common types of visual impairment such as age-related macular degeneration and diabetic retinopathy. NHS Choices estimates around 30% of people who are over 75 have early signs of age-related macular degeneration, and about 7% have more advanced forms.
‘The types of poor vision we are talking about are where you might be able to see your own hand moving in front of you, but you can’t define the fingers,’ explains Stephen.
The glasses have video cameras mounted at the corners to capture what the wearer is looking at, while a display of tiny lights embedded in the see-through lenses of the glasses feed back extra information about objects, people or obstacles in view.
In between, a smartphone-type computer running in your pocket recognises objects in the video image or tracks where a person is, driving the lights in the display in real time.
The extra information the glasses display about their surroundings should allow people to navigate round a room, pick out the most relevant things and locate objects placed nearby.
‘The glasses must look discrete, allow eye contact between people and present a simplified image to people with poor vision, to help them maintain independence in life,’ says Stephen. These guiding principles are important for coming up with an aid that is acceptable for people to wear in public, with eye contact being so important in social relationships, he explains.
The see-through display means other people can see you, while different light colours might allow different types of information to be fed back to the wearer, Stephen says. You could have different colours for people, or important objects, and brightness could tell you how near things were.
Stephen even suggests it may be possible for the technology to read back newspaper headlines. He says something called optical character recognition is coming on, so it possible to foresee a computer distinguishing headlines from a video image then have these read back to the wearer through earphones coming with the glasses. A whole stream of such ideas and uses are possible, he suggests. There are barcode readers in some mobile phones that download the prices of products; such barcode and price tag readers could also be useful additions to the glasses.
Stephen believes these hi-tech glasses can be realised for similar costs as smartphones – around £500. For comparison, a guide dog costs around £25-30,000 to train, he estimates.
He adds that people will have to get used to the extra information relayed on the glasses’ display, but that it might be similar to physiotherapy – the glasses will need to be tailored for individuals, their vision and their needs, and it will take a bit of time and practise to start seeing the benefits.
The exhibit at the Royal Society will take visitors through how the technology will work. ‘The primary aim is to simulate the experience of a visual prosthetic to give people an idea of what can be seen and how it might look,’ Stephen says.
A giant screen with video images of the exhibition floor itself will show people-tracking and depth perception at work. Another screen will invite visitors to see how good they are at navigating with this information. A small display added to the lenses of ski goggles should give people sufficient information to find their way round a set of tasks. An early prototype of a transparent LED array for the eventual glasses will also be on display.
All of this is very much at an early stage. The group is still assembling prototypes of their glasses. But as well as being one of the featured stands at the Royal Society’s exhibition, they have funding from the National Institute of Health Research to do a year-long feasibility study and plan to try out early systems with a few people in their own homes later this year.
Source: PhysOrg - Resarch provided by Oxford University
With increases in asthma and other allergic diseases centered on industrialized nations, a recent hypothesis suggested that the disappearance of specific microorganisms that populate the human body due to modern hygiene practices might be to blame. Now researchers claim they have confirmed this hypothesis by proving that a certain gastric bacterium provides reliable protection against allergy-induced asthma.
The hygiene hypothesis states that modern hygiene practices and overuse of antibiotics have led to a lack of early childhood exposure to infectious agents, symbiotic microorganisms and parasites, which has suppressed the natural development of the body's immune system. Scientists from the University of Zurich and the University Medical Center of the Johannes Gutenberg University Mainz are now saying that the increase in asthma could be put down to the specific disappearance of the gastric bacterium Helicobacter pylori (H. pylori) from Western societies.
Electron micrograph of H. pylori
H. pylori is a bacterium that is resistant to gastric acid and it is estimated that it could currently infect around half of the world's population. While it can cause gastritis, gastric and duodenal ulcers, and stomach cancer under certain conditions, over 80 percent of individuals infected with the bacterium are asymptomatic. However, even if the patient doesn't show any symptoms, H. pylori is often killed off with antibiotics as a precaution.
For their study, the researchers infected mice with H. pylori bacteria at different stages of their development. They found that mice that were infected at just a few days old developed immunological tolerance to the bacterium and reacted insignificantly or not at all to strong, asthma-inducing allergens. Mice that were not infected until they had reached adulthood, however, had a much weaker defense.
"Early infection impairs the maturation of the dendritic cells and triggers the accumulation of regulatory T-cells that are crucial for the suppression of asthma," explains Anne Müller, a professor of molecular cancer research at the University of Zurich.
The researchers also found that if the regulatory T-cells were transferred from infected mice to uninfected mice, they too enjoyed effective protection against allergy-induced asthma. Additionally, mice that had been infected early lost their resistance to asthma-inducing allergens in H. pylori was killed off in them using antibiotics.
According to lung and allergy specialist Christian Taube, a senior physician at III. Medical Clinic of the Johannes Gutenberg University Mainz, the new results that are published in the Journal of Clinical Investigation confirm the hypothesis that the increase in allergic asthma in industrial nations is linked to the widespread use of antibiotics and the subsequent disappearance of micro-organisms that permanently populate the human body.
"The study of these fundamental mechanisms is extremely important for us to understand asthma and be able to develop preventative and therapeutic strategies later on," he said.
Rosse nelle zone più salate, verdi in quelle intermedie e viola nelle regioni più dolci. Sono questi i colori delle acque del nostro pianeta, almeno sulla prima mappa della salinità degli oceani. A realizzarla sono stati i ricercatori della Nasa e dell’Agenzia spaziale argentina (Comisión Nacional de Actividades Espaciales, CONAE) grazie alle prime osservazioni compiute dallo spazio dal satellite Acquarius, confrontate con le misure sperimentali.
Lanciato a giugno, Acquarius è diventato operativo solamente lo scorso agosto, quando gli strumenti a bordo hanno cominciato a registrare i dati relativi alla salinità della superficie degli oceani. Scopo della missione è infatti quello di analizzare come varia la concentrazione del sale nelle acque del pianeta, fondamentale sia per studiare le correnti oceaniche sia per comprendere meglio il ciclo dell’acqua, e per capire come questi fattori siano influenzati dai cambiamenti climatici.
Nell'atlante realizzato dai ricercatori le regioni più salate (sopra i 35 grammi di sale per kg di acqua, considerato il valore medio di mari e oceani) sono quelle dell'Atlantico, del Mediterraneo più interno, delle fasce subtropicali e le acque sul versante ovest dell'India. Mentre le più dolci sono invece le acque all'altezza dell'Equatore, il Pacifico settentrionale, il Mar Caspio, il golfo del Bengala e quelle prossime al circolo polare artico. In alcuni casi questi pattern di salinità sono facilmente collegabili ad alcune caratteristiche regionali, come la foce di alcuni fiumi (per esempio dove sfocia il Rio delle Amazzoni o il Gange) o le precipitazioni (come quelle abbondanti nelle zone equatoriali). Questi infatti, insieme all'evaporazione e allo scioglimento dei ghiacciai, sono i fattori che più possono influenzare la concentrazione di sale nelle acque.
Le regioni rappresentate in nero invece sono quelle per le quali non esistono ancora dei dati. Le informazioni estrapolate dal satellite infatti sono da considerarsi ancora preliminari e con alcune incertezze, che verranno colmate dalle future osservazioni di Acquarius nei tre anni previsti di vita operativa.
Elefantii asiatici au fost mult timp considerati antisociali, însă un nou studiu infirmă această ipoteză, oferind detalii suprinzătoare despre complexitatea retelelor sociale ale acestor pahiderme.
Până acum, despre femelele-elefant din Asia se credea că au doar un mic grup de "prieteni" si putini cunoscuti în afara grupului, spre deosebire de femelele de elefant din savana africană, care trăiesc în grupuri mari si unite.
Acum, un nou studiu demonstrează că femelele de elefant din Asia sunt foarte sociabile si au numeroase prietene. Acesti elefanti sunt capabili de a întretine prietenii puternice chiar si cu exemplarele cu care nu s-au mai văzut de mai bine de un an.
Studiul adaugă elefantii asiatici pe o mică listă de specii, printre care se numără si delfinii, capabile să mentină relatii sociale complexe în ciuda faptului că între doi indivizi nu are loc un contact zilnic, o abilitate considerată ca fiind dificilă din punct de vedere cognitiv.
Elefantii asiatici sunt, de asemenea, extrem de dificil de studiat în sălbăticie, sustine Shermin de Silva, autoarea studiului. Ei trăiesc în păduri dese, asa că cercetătorii sunt în măsură să observe animalele numai din copaci înalti sau privindu-i atunci când se adună la oaze de apă.
În urmă cu 30 de ani, o populatie de elefanti asiatici din Sri Lanka a devenit observabilă din cauza faptului că si-a pierdut pădurea în care trăiau. Oamenii au trunchiat copacii, au transformat tinutul în plantatii de tec si au creat un baraj pe râul din regiune. Astfel au creat rezervatia Uda Walawe. În anul 1972, 308 kilometri pătrati din jurul rezervatiei au fost transformati în Parcul Natioanal Udawalawe. Între 800 si 1.200 de elefanti care trăiau în vechea pădure trăiesc astăzi pe iarba din acest parc.
Noul cadru în care trăiau elefantii le-a permis cercetătorilor să identifice 286 de femele adulte de elefant asiatic. Cercetătorii au urmărit apoi relatiile sociale a 51 de elefanti pe o perioadă de doi ani. Imediat Silva a realizat că elefantii au retele sociale foarte dezvoltate, fapt ce nu era cunoscut până în prezent. Femelele adulte au fost văzute petrecându-si timpul împreună într-o zi, după care au fost văzute singure, iar în zilele următoare au fost văzute în prezenta altor femele.
Oamenii de stiintă au identificat "prietenii" elefantilor drept indivizii care stau la 500 de metri distantă unii de altii, care se miscă împreună, se odihnesc sau îsi împart resursele. Femelele care au multi prieteni au tendinta de a fi tovarăsi necredinciosi, adeseori întrerupând legăturile cu cu indivizii identificati de oamenii de stiintă drept "cei mai buni prieteni". Cele care au mai putini prieteni s-au demonstrat a fi mai loiali acestora.
Desi unii elefanti nu îsi văd companionii pentru o lungă perioadă de timp, acestia pot comunica si în alte feluri: atât chimic, cât si acustic (de multe ori elefantii îsi pun trompa în pământ pentru a detecta vibratiile emise de alti elefanti, care pot servi drept un semnal de alarmă).
Analiza statistică a cercetătorilor referitoare la relatiile elefantilor demonstrează că femelele de elefant asiatic trăiesc într-o societate extrem de fluidă si dinamică, cu indivizi care părăsesc grupurile, după care se reintegrează.
Acum, cercetătorii doresc să înteleagă cum reusesc elefantii să mentină aceste retele sociale complexe, dat fiind că acest lucru solicită o capacitate cognitivă de nivel înalt.
Although this scenario is still several decades away, researchers have been making significant progress in developing early types of biomolecular computers.
In a recent study published in Nano Letters, Computer Science Professor Ehud Shapiro and coauthors from the Weizmann Institute of Science in Rehovot, Israel, have developed a biomolecular computer that can autonomously sense many different types of molecules simultaneously. In the future, this sensing ability could be integrated with a vast biomedical knowledge of diseases to enable computers to decide which drugs to release.
“We envision nanometer-sized computing devices (made of biomolecules) to roam our bodies in search of diseases in their early stage,” coauthor Binyamin Gil from the Weizmann Institute of Science told PhysOrg.com. “These devices would have the ability to sense disease indicators, diagnose the disease, and treat it by administering or activating a therapeutic biomolecule. They could be delivered to the bloodstream or operate inside cells of a specific organ or tissue and be given as a preventive care.”
The development builds on the researchers’ previous demonstration of a biomolecular computer that consists of a two-state system made of biological components (DNA and a restriction enzyme). The computer, which operates in vitro, starts from the Yes state. In each computation step, the computer checks one disease indicator. If all of the indicators for the tested disease are present, the computation ends in the Yes state, namely it makes a positive diagnosis; if at least one disease indicator is not detected, it ends in the No state.
Previously, Shapiro's group showed that this biomolecular computer could detect disease indicators from mRNA expression levels and mutations. In the current study, the researchers have expanded the computer’s ability to also detect disease indicators from miRNAs, proteins, and small molecules such as ATP. At the same time, the computer’s detection method is simpler than before, requiring fewer components and fewer interactions with the disease indicators.
As the researchers explain, sensing a combination of several disease indicators is much more useful than sensing just one, since it allows for better accuracy and greater sensitivity to differences between diseases. For example, they note that in the case of thyroid cancer, the presence of the protein thyroglobulin and the hormone calcitonin can enable a much more reliable diagnosis than if only one of these disease indicators was detected.
Although the ability to detect several disease indicators marks an important step toward in vivo biomolecular computers and programmable drugs, there are still many obstacles that researchers must overcome in the process.
“The biggest challenge is operating such devices in living surrounding like the blood stream or cell's cytoplasm,” Gil said. “Currently we are developing devices that rely on simpler machinery (e.g. no restriction enzyme) or on the cell's own machinery.”
Mike Scharf, the O. Wayne Rollins/Orkin Chair in Molecular Physiology and Urban Entomology, said his laboratory has discovered a cocktail of enzymes from the guts of termites that may be better at getting around the barriers that inhibit fuel production from woody biomass. The Scharf Laboratory found that enzymes in termite guts are instrumental in the insects' ability to break down the wood they eat.
The findings, published in the early online version of the journal PLoS One, are the first to measure the sugar output from enzymes created by the termites themselves and the output from symbionts, small protozoa that live in termite guts and aid in digestion of woody material.
"For the most part, people have overlooked the host termite as a source of enzymes that could be used in the production of biofuels. For a long time it was thought that the symbionts were solely responsible for digestion," Scharf said. "Certainly the symbionts do a lot, but what we've shown is that the host produces enzymes that work in synergy with the enzymes produced by those symbionts. When you combine the functions of the host enzymes with the symbionts, it's like one plus one equals four."
Scharf and his research partners separated the termite guts, testing portions that did and did not contain symbionts on sawdust to measure the sugars created.
Once the enzymes were identified, Scharf and his team worked with Chesapeake Perl, a protein production company in Maryland, to create synthetic versions. The genes responsible for creating the enzymes were inserted into a virus and fed to caterpillars, which then produce large amounts of the enzymes. Tests showed that the synthetic versions of the host termite enzymes also were very effective at releasing sugar from the biomass.
They found that the three synthetic enzymes function on different parts of the biomass.
Two enzymes are responsible for the release of glucose and pentose, two different sugars. The other enzyme breaks down lignin, the rigid compound that makes up plant cell walls.
Lignin is one of the most significant barriers that blocks the access to sugars contained in biomass. Scharf said it's possible that the enzymes derived from termites and their symbionts, as well as synthetic versions, could be more effective at removing that lignin barrier.
Sugars from plant material are essential to creating biofuels. Those sugars are fermented to make products such as ethanol.
"We've found a cocktail of enzymes that create sugars from wood," Scharf said. "We were also able to see for the first time that the host and the symbionts can synergistically produce these sugars."
Next, Scharf said his laboratory and collaborators would work on identifying the symbiont enzymes that could be combined with termite enzymes to release the greatest amount of sugars from woody material. Combining those enzymes would increase the amount of biofuel that should be available from biomass.
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