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mercredi 2 juillet 2008
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If you ever have cruised on California's Highway 1, you know it offers spectacular views of the Pacific ocean. But several areas of this road are potentially dangerous because they can be affected by landslides. This is why the U.S. National Science Foundation (NSF) is helping the California Department of Transportation (Caltrans) to build a kilometer-long tunnel under Devil's Slide located South of San Francisco. The project engineers will be helped by a software dubbed gVT (for 'geotechnical Visualization Tool') developed at Virginia Tech. This tool, based on ultra-precise laser scans, will improve both safety and construction progress. But read more...
Before going further, you can see above a map of the Caltrans's Devil's Slide Project. "The project calls for construction of two tunnels beneath San Pedro Mountain, each 30-feet wide and 4,200-feet long. At the northern end, a 1,000-feet bridge will span the valley at Shamrock Ranch. A re-alignment of Route 1 at the southern end will provide safe transition into and out of the tunnel. [...] The bypassed section of Route 1, together with 70 acres of State right of way, will be available for public access and recreational use following the planned tunnel opening in 2011." (Credit: Caltrans) From the above link, you'll have access to many photos and videos.
Now, let's go back to the NSF news release about the gVT software. You can see on the left a "close-up image of the tunnel roof showing a gVT measurement location. The arrow is a vector perpendicular to a surface that marks a discontinuity between rock layers. The orientation of the arrow in space gives the azimuth and slope of the surface." Credit: Jeramy Decker, Kiewit Corp.) Here is a link to a slightly larger version.
Here are some additional details from NSF. "Developed as part of a National Science Foundation Information Technology Research Initiative (ITR) project, the software, called "geotechnical Visualization Tool" (gVT), converts imagery of millions of rock-surface points--collected at a safe distance by a laser scanner--into an easily manipulated web of information. The data become a permanent digital record of the newly exposed material. The scan data, at a resolution of 5 millimeters, provides information that the software program packages into enormous visualizations incorporating up to 10 meters of excavated tunnel. Engineers then use gVT to spot potential hazards to both the tunnel and the construction crews before weaknesses in the rock have a chance to trigger a collapse."
Even the engineers were surprised by the precision offered by the software. "The information is so detailed that researchers can observe where rock layers are separating and how fractures are oriented. Researchers can even recreate sections of rock after they have fallen, providing a critical asset for determining where and how to safely drill. Because the data is portable, engineers can conduct all of the analyses from their home base at any time, far from the danger of the tunnel. 'Geologic maps have traditionally been made using manual measurements taken by geologists directly on the rock,' said Joseph Dove, the lead developer of gVT at Virginia Tech."
Now, let's move to the NSF-funded AMADEUS project (Adaptive and Real-Time Geologic Mapping, Analysis and Design of Underground Space). Here is a short introduction. "Underground excavations are used for a wide variety of civilian and military purposes, including mining, road & railway tunnels, and caverns. Permanent storage of the current U.S. stockpile of nuclear wastes will utilize large underground excavations. With increasing world population, demand for underground construction is expected to accelerate in the future. From an Information Technology (IT) viewpoint, design and construction of underground facilities are just emerging from the dark ages. Rock failure in underground mines and tunnel construction continue to claim lives, and the tunneling industry is still beset by frequent failures." Please check the above link for more details.
Finally, if you're really interested by this technology, you can read "Building, Updating and Verifying Fracture Models in Real Time for Hard Rock Tunneling," the dissertation submitted by one of the researchers, Jeramy Bruyn Decker, to obtain his degree of Doctor of Philosophy in Civil Engineering (Blacksburg, Virginia, April 20, 2007, PDF format, 161 pages, 3.39 MB). Decker now works for Kiewit Pacific Co., a subsidiary of Kiewit Corporation which is the contractor 'building' the Devil's Slide tunnel.
Sources: National Science Foundation news release, June 30, 2008; and various websites
You'll find related stories by following the links below.
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mardi 1 juillet 2008
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Many fireworks will be launched in July, at least in the U.S. and in France. A recent American Chemical Society's Weekly PressPac briefly describes how chemists are developing environmentally friendlier compounds for fireworks (scroll to article #5 in the PressPac). Current 'fireworks, flares and other so-called pyrotechnics commonly include potassium perchlorate to speed up the fuel-burning process.' But perchlorate has been identified as a potential human health hazard causing thyroid damage. So 'researchers recently developed new pyrotechnic formulas that replace perchlorate with nitrogen-rich materials or nitrocellulose that burn cleaner and produce less smoke.' But read more...
You can see above some generic fireworks. (Credit: Courtesy of Wikimedia Commons, via this EurakAlert! page) As mentioned above, "scientists plan to replace potassium perchlorate, a harmful substance widely used in fireworks, with cleaner, less toxic materials."
Let's first look at why potassium perchlorate can be dangerous with the help of an article from Chemical & Engineering News (C&EN) (Volume 86, Number 26, Pages 14-18). "Over the years, perchlorate has become the oxidizer of choice for most pyrotechnic applications, supplanting less stable chlorate oxidants that were the cause of numerous deadly explosions. 'Potassium perchlorate is the ideal oxygen donor to use in pyrotechnics in terms of safety, cost, and reproducibility,' says John A. Conkling, a pyrotechnics expert and adjunct professor of chemistry at Washington College, in Chestertown, Md. Unfortunately, perchlorate has also been identified as a potential human health hazard. Studies suggest that it inhibits the thyroid's ability to take up iodine from the bloodstream and can reduce the production of thyroid hormone. And because the anion is highly water soluble, it readily slips into groundwater."
Robert G. Shortridge, a scientist in the Pyrotechnic Operations Branch at the Crane Division of the Naval Surface Warfare Center, and his colleagues "have been working to replace the perchlorate in colored signal flares. So far, they've had the most success with red signal flares that use strontium-based oxidants. Their perchlorate-free formulation is about to undergo safety testing, as well as tests in which the flares will be loaded into the signal hardware and subjected to the environmental rigors they would experience in service. "We intend to pass all of them while making the environment a little safer too," Shortridge says of the tests."
The C&EN article also warns us that coloring agents used during fireworks could be friendlier to the planet. "The other area in which pyrotechnics could improve from an environmental standpoint is their use of coloring agents. To achieve colored fireworks and flares, pyrotechnic makers employ metals or metal compounds that emit light in the visible spectrum. Red hues come from strontium, sodium glows yellow, barium burns green, and blues and greens come from copper. At one time, mercury and lead compounds were used as colorants, but they were phased out long ago. Ironically, the modern pyrotechnic components that could use some "greening" are the barium compounds that give fireworks and flares their green color."
If you're interested in pyrotechnics, you must read the very well documented -- but long -- C&EN article. However, if you have no time for this, "you should know that most experts think the level of pollution from shooting off fireworks outdoors a couple of times per year is actually pretty small." So enjoy the Fourth of July and Bastille day fireworks without feeling too guilty. Please keep in mind that eco-friendly fireworks are not as cost-effective as conventional fireworks today.
Sources: American Chemical Society's Weekly PressPac, June 25, 2008; Bethany Halford, Chemical & Engineering News, June 30, 2008 issue; and various websites
You'll find related stories by following the links below.
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lundi 30 juin 2008
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The theme of this post is slightly off focus of this blog. But it's not often that archeologists make an exciting discovery in my own town, Paris, France. In fact, these archeologists have found that human groups of hunter-gatherers were living in Paris around 7600 BC during the Mesolithic period. They've found thousands of flint arrowheads and fragments of animal bones near the Seine river in the 15th arrondissement just one mile from the Eiffel Tower -- and half a mile from where I live. I visited the dig site last Saturday, and it was quite impressive. But read more...
You can see above a general view of the excavation site where this discovery has been done. (Credit: Laurent Petit, INRAP) Here is a link to additional information (in French) and to a larger version of this picture.
And you can see above some of the Mesolithic flint arrows discovered by the French archeologists. (Credit: D. Gliksman, INRAP) In case you want to know, INRAP is an acronym for "Institut National de Recherches Archéologiques Préventives," the French government agency for preventive archaeology. It always intervenes on sites where new buildings are scheduled.
So what did the archeologists find? This was widely reported by the French press, but not so much in the rest of the world. Here are some details given by The Independent, UK. "An area about the size of a football field on the south-western edge of the city, close to the banks of the river Seine, has yielded thousands of flint arrowheads and fragments of animal bone. The site, between the Paris ring road and the city's helicopter port, is believed by archaeologists to have been used, nearly 10,000 years ago, as a kind of sorting and finishing station for flint pebbles washed up on the banks of the river. Once the dig is complete, the site will be occupied by a plant for sorting and recycling the refuse generated by the two million Parisians of the 21st century."
Of course, you all know that Paris is a very old city. But these excavations show that there were Parisians 3,000 years than previously thought. "'You could say that we've come full circle,' said Bénédicte Souffi, one of the two archaeologists in charge of the site. 'Our ancestors were sorting rubbish from usable objects here in 7600 BC. We are going to be doing much the same thing on a more elaborate scale. Maybe, there is a lesson there.' The oldest previous human settlement discovered within the Paris city boundaries dates back to about 4500 BC -- a fishing and hunting village beside the Seine at Bercy near the Gare de Lyon railway station."
According to the INRAP team, the site has been preserved by silt from the frequent flooding of the Seine -- and also because the river was using another branch 250 meters away from the current main river.
For more information about this archeological discovery, here are two links to French sites -- so you'll need to know a little bit of French to enjoy.
The archeologists have up to the end of July 2008 to end their dig. After that, the site will be occupied by a plant for sorting and recycling the 15,000 tons of refuse generated by Parisians. Here is a link to this future recycling center (also in French), which ironically will connect people living 10,000 years apart.
Sources: John Lichfield, The Independent, June 26, 2008; and various websites
You'll find related stories by following the links below.
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dimanche 29 juin 2008
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A Columbia University computer science professor has co-founded a New York-based company named Sense Networks to sell tracking software to other companies. It is also distributing a free version of this software named Citysense, which shows on your cell phone where the wild things are happening in your own town. Citysense 'uses advanced machine learning techniques to number crunch vast amounts of data emanating from thousands of cell-phones, GPS-equipped cabs and other data devices to paint live pictures of where people are gathering.' Citysense is available today in San Francisco before being soon deployed in Chicago and five other U.S. cities. But read more...
You can see on the left how "Citysense shows the overall activity level of the city, top activity hotspots, and places with unexpectedly high activity, all in real-time." (Credit: Sense Networks) Here is a link to additional information and a larger version of this picture. As you can see, the application is available on Blackberry devices. But an iPhone version is in the works.
This software has been developed by Tony Jebara, an Associate Professor in Computer Science at Columbia University and director of the Machine Learning lab. Jebara founded Sense Networks with several partners including MIT's Alex Pentland. Here is a link to the Citysense web site.
And here are some quotes from Jebara about this project. "'We are providing consumers with free applications on their mobile phones for visualizing several cities: 'where is everyone?,' 'where should I go eat?,' 'which jazz bar would I like?,' 'where would I like to go shopping?' and so on,' Jebara says. Gaining access to the hottest locales with Citysense involves a trade off for users: information on their own whereabouts is also fed into the system. While all information gathered is anonymous, the data could be a goldmine for marketers and consumer researchers looking to enhance sales pitches, learn where people actually shop, or don’t, and tweak emerging retail trends as they evolve."
But how exactly does Citysense work? "Citysense is an application that operates on the Sense Networks Macrosense platform, which analyzes massive amounts of aggregate, anonymous location data in real-time. Macrosense is already being used by business people for things like selecting store locations and understanding retail demand. But we asked ourselves: with all this real-time data, what else could we do for a city? Nightlife enhancement was the obvious answer. This release is just a test, and we're interested in your feedback on how to make the application better. You'll find a feedback button in Citysense."
And what's next? "When you use Citysense, the application learns about the kinds of places you like to go from GPS – without ever sharing that information. In its next release, Citysense will not only tell you where everyone is right now, but where everyone like YOU is right now. The application will compare your history and preferences with those of other users, and show you where you're most likely to find people with similar tastes at that moment. So each person's nightlife map will look a little different, and will display a unique top hotspot list. Cool, huh? That's why we save your location when you use Citysense: to remember what you like. Of course, you don't have to keep a personalized nightlife profile. You can delete your data from our system anytime you want. You created your data: you own it."
The Citysense application was widely covered by the press at the beginning of June 2008 -- check the Sense Networks Media Center for example. One of the most interesting features of Citysense was covered by Brady Forrest in a post on O'Reilly Radar (June 9, 2008). "In addition to these sexy visualizations they included an alarm lock that will wake you up earlier if the city is busier than normal before your commute (set it for 7:30 and sometimes it will get you up at 7:28, but on busier days you might be hitting the snooze at 7:21)." I'm not sure to like this feature...
Sources: David Poratta, Columbia University News, June 20, 2008; and various websites
You'll find related stories by following the links below.
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samedi 28 juin 2008
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University of Bristol researchers have developed a non-intrusive visual surveillance system for wildlife habitats. They've used their system to monitor the behavior of 20,000 African penguins on Robben Island in South Africa. By definition, conventional tagging techniques can only monitor animals which have been tagged. On the contrary, the 'Penguin Recognition Project' relies on visual recognition software. The scientists claim that they can correctly identify an individual penguin 'with around 98 per cent reliability' -- how can they measure this? They also claim that their approach could be used to monitor other endangered species, such as zebras or sharks. But read more...
You can see above this "computer vision system in action identifying African penguins on their way from the colony to the beach. Green boxes indicate the penguins detected as species members in near-frontal poses, a yellow bounding box shows that a penguin has been identified as an individual." (Credit: Spot the Penguin Project)
The researchers have taken advantage of a specific characteristic of these African penguins. "African penguins carry a pattern of black spots on their chests that does not change from season to season during their adult life. As far as scientists can tell, no two penguins have exactly the same pattern. The researchers have developed a real-time system that can locate African penguins whose chests are visible within video sequences or still images. An extraction of the chest spot pattern allows the generation of a unique biometrical identifier for each penguin. These biometric data can then be used to identify individual, African penguins from video or photographic images by comparison with a population database."
They also claim that their recognition system works very well and could be used to monitor other endangered species. "Provided that a good image of a penguin can be extracted, the system can correctly identify the individual with around 98 per cent reliability. The current limitation of the system, based on one camera, is that some passing penguins are hidden behind others, or the lighting is poor. The researchers are currently working to overcome these limitations both by combining images from intelligent pan-tilt-zoom cameras, and by using infra-red imaging to provide data both day and night. The basic image-recognition system has also been trialled with zebras, sharks and, in principle, can be extended to any species with complex surface patterns."
You'll find more information by visiting the Spot the Penguin Project website. This project description will give you access to a 19 seconds video from which I've picked the above picture. It also gives more details about the current prototype of the project.
- Vision Software: As one essential part of our research we focus on developing the 'intelligent' software that allows systems to make sense of complex camera images and interpret animals and their patterns as individual entities.
- Hardware Architecture: Our current prototype system has a distributed design: client systems gather data at different locations in the penguin colony while a central server holds the population data. All necessary software components are created to run on relatively inexpensive consumer hardware.
- Data Flow and Networking: The cameras capture images and send a time-stamped version of them in a live stream to locally connected laptop computers which identify members of species in real-time. The relevant areas of interest in each image (the penguin chest patterns) are then transferred to local hotspots using a wireless network.
Finally, you can participate in a competition named Can you spot the penguin? Here are the simple rules. "If you can do what our Penguin Recognition System can do, you have the chance of winning a trip to work as a volunteer on an Earthwatch expedition for two weeks with the penguins on Robben Island in South Africa."
Sources: University of Bristol news release, June 27, 2008; and various websites
You'll find related stories by following the links below.
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vendredi 27 juin 2008
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Oak Ridge National Laboratory (ORNL) researchers have developed a super-sensitive explosives detector which uses a laser and a device that converts reflected light into sound. Interestingly, the technique they've used is based on earlier works of Alexander Graham Bell in the late 1880s. In their experiments, the researchers used three explosives such as TNT and 'were able to detect trace residues with lasers 100 times less powerful than those of competing technologies.' Right now, they can detect explosives 20 meters away from their system, but 'they believe they can achieve detection at distances approaching 100 meters.' But read more...
You can see above one of the ORNL researchers, Charles Van Neste, using his prototype laser to check if explosives are inside a briefcase. (Credit: Jason K. Richards, Creative Media, Oak Ridge National Laboratory, via this Science Daily link)
This research work has been conducted at the Nanoscale Science & Devices Group, which is part of the Biosciences Division at Oak Ridge National Laboratory (ORNL). The team was composed of Thomas Thundat, leader of the group, Larry Senesac and Charles Van Neste.
Here are some details about the ORNL's technique. It "involves illuminating the target sample with an eye-safe pulsed light source and allowing the scattered light to be detected by a quartz crystal tuning fork. 'We match the pulse frequency of the illuminating light with the mechanical resonant frequency of the quartz crystal tuning fork, generating acoustic waves at the tuning fork's air-surface interface,' said Charles Van Neste. 'This produces pressures that drive the tuning fork into resonance.' The amplitude of this vibration is proportional to the intensity of the scattered light beam falling on the tuning fork, which because of the nature of quartz creates a piezoelectric voltage."
This research work has been published by several scientific journals in 2008.
The first article was included in Applied Physics Letters under the name "Standoff detection of explosive residues using photothermal microcantilevers" (Volume 92, Article 134102, April 1, 2008). Here is a link to the abstract. "Standoff detection of trace explosives is gaining attention due to its immediate relevance in countering terrorist threats based on explosive devices. However, most currently available standoff techniques rely on expensive, complex, and bulky equipment. We have demonstrated highly selective and sensitive standoff detection of explosive residues on surfaces by using photothermal spectroscopy carried out with bimaterial microcantilever sensors. The demonstrated sensitivity of the technique, 100 ng/cm2, is sufficient to detect the explosive contamination generally found on explosive devices. The sensitivity of the technique can be further improved by optimizing the bimaterial cantilever and by using higher intensity infrared sources."
The researchers also published a paper in the Journal of Applied Physics under the title "Trace explosive detection using photothermal deflection spectroscopy" (Volume 103, Issue 9, Article 094906, May 2, 2008). Here is a link to the abstract. "Satisfying the conditions of high sensitivity and high selectivity using portable sensors that are also reversible is a challenge. Miniature sensors such as microcantilevers offer high sensitivity but suffer from poor selectivity due to the lack of sufficiently selective receptors. Although many of the mass deployable spectroscopic techniques provide high selectivity, they do not have high sensitivity. Here, we show that this challenge can be overcome by combining photothermal spectroscopy on a bimaterial microcantilever with the mass induced change in the cantilever's resonance frequency. Detection using adsorption-induced resonant frequency shift together with photothermal deflection spectroscopy shows extremely high selectivity with a subnanogram limit of detection for vapor phase adsorbed explosives, such as pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), and trinitrotoluene (TNT)."
Finally, Applied Physics Letters accepted a third paper under the name "Standoff photoacoustic spectroscopy" (Volume 92, Article 234102, June 12, 2008). Here is a link to the abstract. Here, we demonstrate a variation of photoacoustic spectroscopy that can be used for obtaining spectroscopic information of surface adsorbed chemicals in a standoff fashion. Pulsed light scattered from a target excites an acoustic resonator and the variation of the resonance amplitude as a function of illumination wavelength yields a representation of the absorption spectrum of the target. We report sensitive and selective detection of surface adsorbed compounds such as tributyl phosphate and residues of explosives such as trinitrotoluene at standoff distances ranging from 0.5–20 m, with a detection limit on the order of 100 ng/cm2."
Sources: Oak Ridge National Laboratory news release, June 25, 2008; and various websites
You'll find related stories by following the links below.
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jeudi 26 juin 2008
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A team of U.S. engineers and researchers have developed a laser surgery probe which targets individual cancer cells. This 'microscalpel' can destroy a single cancerous cell while leaving nearby cells intact. According to the lead researcher, 'You can remove a cell with high precision in 3-D without damaging the cells above and below it. And you can see, with the same precision, what you are doing to guide your microsurgery.' This 'microscalpel' is certainly promising, but I have some doubts. As a cancer involves many cells, how would a human operator be able to remove all of them if he can only kill them one by one? And how could he target all these cancerous cells with this laser tool? It would certainly take lots of time. But read more...
You can see above the combined effects of "two-photon microscopy and femtosecond laser microsurgery on a single layer of breast carcinoma cells. (a) Two photon image of a single layer of live breast carcinoma cells after uptake of calcein AM taken prior to irradiation with high intensity pulses. (b) The same FOV [field of view] as (a), immediately after irradiation with a single pulse at 280 nJ pulse energy. Average laser power used for imaging in both images was 10 mW. Both images were averaged over 5 seconds at 10 fps and spatially filtered. Note that the targeted cell has lost fluorescence while the cell touching the targeted cell is left intact. Scale bars are 20 ìm." (Credit: Adela Ben-Yakar and colleagues)
This research project has been led by Adela Ben-Yakar, Assistant Professor in the Mechanical Engineering Department of the University of Texas at Austin. She was helped by several members of her research group about femtosecond lasers. She also collaborated with Olav Solgaard, Associate Professor of Electrical Engineering at Stanford University.
Before going further, here is a short description of femtosecond lasers and their medical usages. "Femtosecond lasers produce extremely brief, high-energy light pulses that sear a targeted cell so quickly and accurately the lasers' heat has no time to escape and damage nearby healthy cells. As a result, the medical community envisions the lasers' use for more accurate destruction of many types of unhealthy material. These include small tumors of the vocal cords, cancer cells left behind after the removal of solid tumors, individual cancer cells scattered throughout brain or other tissue and plaque in arteries."
Now, let's look at what did Ben-Yakar and her colleagues. "Ben-Yakar's laboratory has overcome technological challenges to create a microscope system that can deliver femtosecond laser pulses up to 250 microns deep inside tissue. The system includes a tiny, flexible probe that focuses light pulses to a spot size smaller than human cells. [...] Within a few years, Ben-Yakar expects to shrink the probe's 15-millimeter diameter three-fold, so it would match endoscopes used today for laparoscopic surgery. The probe tip she has developed also could be made disposable -- for use operating on people who have infectious diseases or destroying deadly viruses and other biomaterials."
For more information, please read the University of Texas at Austin news release mentioned in the introduction. And please note that this research work has been published by Optics Express under the name "Miniaturized probe for femtosecond laser microsurgery and two-photon imaging" (Vol. 16, Issue 13, Pages 9996-10005, June 23, 2008).
Here is a link to the abstract. "Combined two-photon fluorescence microscopy and femtosecond laser microsurgery has many potential biomedical applications as a powerful 'seek-and-treat' tool. Towards developing such a tool, we demonstrate a miniaturized probe which combines these techniques in a compact housing. The device is 10 x 15 x 40 mm3 in size and uses an aircore photonic crystal fiber to deliver femtosecond laser pulses at 80 MHz repetition rate for imaging and 1 kHz for microsurgery. A fast two-axis microelectromechanical system scanning mirror is driven at resonance to produce Lissajous beam scanning at 10 frames per second. Field of view is 310 µm in diameter and the lateral and axial resolutions are 1.64 ìm and 16.4 ìm, respectively. Combined imaging and microsurgery is demonstrated using live cancer cells."
From the above link, you can have access to the full article. I'm not including a link, because it is a variable one. Anyway, the above figure and its caption were picked from this article. And before getting to the conclusions of this paper, here are some acronyms used in it: MEMS (microelectromechanical systems), FLMS (femtosecond laser microsurgery), TPM (two-photon microscopy) and NA (numerical aperture).
So what's next? "Future design improvements such as a metallic-coated high reflectivity MEMS mirror and a high-NA miniature objective lens, which will provide increased power delivery and improved collection efficiency, respectively, can enable imaging of cellular autofluorescence with the probe. An increase in numerical aperture will also be beneficial for precise FLMS inside bulk tissue, where tighter focusing can help to reduce the pulse energy and avoid collateral damage arising from nonlinear affects. Meanwhile, novel two-photon contrast agents, such as bright luminescent gold nanorods, can be used to reduce the required excitation power by a couple of orders of magnitude in addition to providing molecularly specific imaging."
The researchers also think that their system might be used for other applications. "Fiber-coupled systems with near-video rate imaging and high precision surgery capabilities such as the one presented here can be used for live animal studies for developing clinical techniques. The optical design approach presented in this paper shows great promise and could find applications in such disparate fields as oncology, dermatology, and neurosurgery."
Sources: The University of Texas at Austin news release, June 23, 2008; and various websites
You'll find related stories by following the links below.
7:32:01 PM
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© Copyright
2008
Roland Piquepaille.
Last update:
02/07/2008; 19:41:26.
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