Back to the main page

Archives Of Science Blog

Subscribe To Science Blog RSS Feed  RSS content feed What is RSS feed?

June 10, 2007, 9:16 PM CT

Aquatic Systems Buried Under Antarctic Ice

Aquatic Systems Buried Under Antarctic Ice
An artist's representation of the aquatic system scientsist believe is buried beneath the Antarctic ice sheet.
Credit: Zina Deretsky / NSF
The National Science Foundation (NSF) should work within the environmental framework of the international Antarctic Treaty system to develop a global scientific consensus on minimally disruptive ways to investigate one of the "last unexplored places on Earth"--a unique system of lakes, and the aquatic systems that may connect them, buried thousands of meters under the Antarctic ice sheet--according to a newly released report.

To avoid contaminating these lakes and other features, which scientists have only recently discovered and which have been cut off from the outside world for millions of years, the report calls for NSF to work with international scientific organizations and Treaty signatories to develop a management plan for any potential exploration efforts and, as part of that plan, "ensure that the environmental management of subglacial environments is held to the highest standards".

The report, "Exploration of Antarctic Subglacial Aquatic Environments: Environmental and Scientific Stewardship," was released in early May by the National Research Council of the National Academies of Science.

But before any efforts are made to take any samples, the report stresses, much more detailed surveys need to be made to catalogue the subglacial aquatic network and allow it to be afforded Treaty protection. Such a survey, while enabling the protecting of the entire system, would also allow for designating certain features more useful for scientific research and presenting less of a risk of widespread contamination of a subglacial "watershed".........

Posted by: Nora      Read more         Source

June 10, 2007, 8:00 PM CT

New tool for spectroscopy

New tool for spectroscopy
Image courtesy of
Scientists at the National Institute of Standards and Technology (NIST) have developed two new calibration tools to help correct and validate the performance of analytic instruments that identify substances based on fluorescence.

Recent years have seen a significant increase in the development and use of fluorescence-based analytic techniques. Scientists can detect, measure and identify unknown substancespotentially including chemical and biological weaponsusing spectroscopic techniques. In fluorescence spectroscopy, researchers send a beam of light at a certain wavelength into a sample, exciting electrons in particular analytes or fluorescent labels, which then emit light at longer wavelengths with measurable energy levels. This resulting spectral signature, recorded by a fluorescence spectrometer, is distinct for different fluorescent compounds. A number of of these assays are being used in areasincluding clinical diagnostics, environmental monitoring and drug developmentwhere regulatory requirements are strict and may require standards for instrument qualification and method validation.

To meet these needs, NIST has developed two ready-to-use, fluorescent glass Standard Reference Materials (SRMs), about the size of a pack of a gum, whose certified values can be used to correct fluorescence emission spectra for relative intensity. SRM 2940 (Orange emission) has certified values for emission wavelengths from 500 to 800 nanometers when excited with light at 412 nm; SRM 2941 (Green emission) has certified values for emission wavelengths from 450 to 650 nm when excited with light at 427 nm.........

Posted by: John      Read more         Source

June 6, 2007, 9:38 PM CT

Helping carbon nanotubes get into shape

Helping carbon nanotubes get into shape
Caption: A carbon nanotube bundle before (left) and after (right) densification.
Credit: Rensselaer/Liu
Troy, N.Y. -- Scientists at Rensselaer Polytechnic Institute have developed a new method of compacting carbon nanotubes into dense bundles. These tightly packed bundles are efficient conductors and could one day replace copper as the primary interconnects used on computer chips and even hasten the transition to next-generation 3-D stacked chips.

Theoretical studies show that carbon nanotubes, if packed closely enough together, should be able to outperform copper as an electrical conductor. But because of the way carbon nanotubes are grown in sparse nanoscale forests where carbon molecules compete for growth-inducing catalysts researchers have been unable to successfully grow tightly packed bundles.

James Jiam-Qiang Lu, associate professor of physics and electrical engineering at Rensselaer, together with his research associate Zhengchun Liu, decided to investigate how to densify carbon nanotube bundles after they are already grown. He detailed the results of the post-growth densification project on June 6 at the Institute of Electrical and Electronics Engineers International Interconnect Technology Conference (IITC) in Burlingame, Calif.

Lus team discovered that by immersing vertically grown carbon nanotube bundles into a liquid organic solvent and allowing them to dry, the nanotubes pull close together into a dense bundle. Lu attributes the densification process to capillary coalescence, which is the same physical principle that allows moisture to move up a piece of tissue paper that is dipped into water.........

Posted by: John      Read more         Source

June 1, 2007, 9:41 PM CT

How to Rip and Tear a Fluid

How to Rip and Tear a Fluid
Credit: J. Gladden, A. Belmonte (Penn State)
In a simple experiment on a mixture of water, surfactant (soap), and an organic salt, two scientists working in the Pritchard Fluid Mechanics Laboratory at Penn State have shown that a rigid object like a knife passes through the mixture at slow speeds as if it were a liquid, but rips it up as if it were a rubbery solid when the knife moves rapidly. The mixture they study shares properties of a number of everyday materials -- like toothpaste, saliva, blood, and cell cytoplasm -- which do not fall into the standard textbook cases of solid, liquid, or gas. Instead, these "viscoelastic" materials can have the viscous behavior of a fluid or the elastic behavior of a solid, depending on the situation. The results of these experiments, which are reported in the current issue of the journal Physical Review Letters and are featured on its cover, provide new insights into how such materials switch over from being solid-like to being liquid-like.

"As a child will swish its finger through an unknown liquid to find out what it is, we built an experiment to pull a cylinder through this viscoelastic material, to learn how it responds," explains Andrew Belmonte, associate professor of mathematics at Penn State and a member of the research team. Their study revealed experimentally, for the first time, the response of a viscoelastic material to increasingly extreme conditions of flow. "We observed that flow happens at slow speeds, cutting happens at intermediate speeds, and tearing happens at the highest speeds," says Joseph R. Gladden, a co-author of the research paper, who collaborated on the study while he was a postdoctoral scholar at Penn State. The scientists also observed that the viscoelastic material heals in the wake of the tear, as a torn solid would not, and recovers completely after several hours. "Surprisingly, the strength of the material when it acts like a solid is essentially the same as its surface tension as a liquid. This fact reconnects our understanding of these materials between the extremes of flow and fracture," said Belmonte.........

Posted by: John      Read more         Source

May 25, 2007, 3:26 PM CT

Antenna Calibrations Extended to 60-110 GHz

Antenna Calibrations Extended to 60-110 GHz
NIST engineer Katherine MacReynolds prepares a new NIST "tabletop" range for characterizing high-performance antennas, such as horn antennas (small gold pyramids) operating at 94 Gigahertz. The surrounding blue foam cones absorb electromagnetic fields to reduce scattering from nearby objects, thereby improving measurement accuracy.
Credit: © 2006 Geoffrey Wheeler
The National Institute of Standards and Technology (NIST) has developed a new "tabletop" sized facility to improve characterization of antennas operating in the 60 to 110 gigahertz (GHz) frequency range. This extended frequency capability serves needs for advanced civilian and military communication and radar systems.

A number of electronic systems are moving to higher frequencies to attain higher channel capacity, better spatial resolution and other advantages. The new measurement facility will help accelerate development of technologies such as automobile collision-prevention radars, which operate at 94 GHz and require antennas small enough to be integrated into car bumpers. Improved NIST antenna calibration capability also helps to assure the accuracy of a number of systems. "NIST is the start of the measurement traceability chain," says Perry Wilson, leader of the Radio Frequency Fields Group. "For instance, we calibrate the probes used by aerospace companies to calibrate instruments launched on satellites and other critical systems. Weather satellites are an example; improvements in antenna accuracy mean better data for weather models, resulting in better weather predictions".

The new facility continues NIST's history of innovation in antenna measurements, building on the "extrapolated gain" technique developed several decades ago. The original extrapolation range and techniques made it practical for scientists to accurately compute an antenna's far-field characteristics based on near-field measurements. By making the range compact, costs are significantly reduced. In addition, the extrapolation technique uses over-sampling and averaging techniques to minimize the effects of scattering and range imperfections.........

Posted by: John      Read more         Source

Thu, 24 May 2007 01:21:54 GMT

Bromus tectorum

Bromus tectorum
I'm back from Botany BC and the subsequent trip to southeast Washington state. I wish I could report that all went well, but a post-Botany BC bout of illness (that left more than half of the attendees sick) hit me as well. I didn't spend nearly as much time photographing and exploring as I had planned, needless to say.

That said, I did manage to find a number of uncommon plants along the way. Today's plant, however, isn't one of them. In fact, it's likely one of the most ubiquitous plants in temperate areas of the world: cheatgrass or drooping brome. Native to southern Europe and southwestern Asia, the Global Invasive Species Database (GISD) lists Bromus tectorum has having invaded “most of Europe, southern Russia, western and central Asia, Japan, South Africa, Australia, New Zealand, Iceland, Greenland, Canada and the United States.”. The Germplasm Resources Information Network entry adds a few more areas to the above list, including southern South America, India and Pakistan. In the second photograph, Bromus tectorum covers the right and foreground hillsides, and occurs in patches on the left hillside. In the third photograph, it forms most of the groundcover between the sagebrushes. Why is it such a successful invader? The GISD notes: “It usually thrives in disturbed areas preventing natives from returning to the area. Disturbance such as overgrazing, cultivation, and frequent fires encourage invasion. Once established the natives cannot compete and the whole ecosystem is altered.”.

I chose to feature Bromus tectorum today for a couple reasons. Most important of these is that it is a species named and described by Carl Linnaeus in Species Plantarum. As of today, it's been 300 years since the birth of Linnaeus, “the father of modern taxonomy”. The New York Times has a write-up: “The 300th Birthday of the Man Who Organized All of Nature”. Happy Birthday, Carl!

My other reason for featuring this weedy invasive is a bit of an ironic one. Yesterday was The International Day for Biological Diversity (did you know? hear about it on the news at all?) and Bromus tectorum growing in swathes is symbolic of the loss of biodiversity in many dryland areas.

A final note to end this ramble: these photographs were taken in the Saddle Mountain area of the Hanford Reach National Monument. Wikipedia has a summary of the Hanford Site (I didn't photograph any radioactive tumbleweed, by the way).

Posted by: Daniel Mosquin      Read more     Source

Mon, 21 May 2007 02:57:10 GMT

Large Snow Melt in Antarctica Worries Scientists

Large Snow Melt in Antarctica Worries Scientists
The rising temperature has melted the snow blanket in a California-sized region of Antarctica, NASA said after receiving new satellite imagery.

Scientists from NASA’s Jet Propulsion Laboratory and the University of Colorado were quite worried after images showed that vast ice has melt in the region, where it was deemed quite unlikely.

They went on to describe it as the most significant melt observed using satellites in the last three decades.

Konrad Steffen, director of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, said melting on such a large scale had not been witnessed earlier.

He said

Antarctica has shown little to no warming in the recent past with the exception of the Antarctic Peninsula, but now large regions are showing the first signs of the impacts of warming

For their research, the scientists used satellite scatterometry, a sophisticated imaging system, which can distinguish between recently frozen ice and snow which remain frozen since a long time.

melted the snow blanket

Posted by: Irani      Read more     Source

May 17, 2007, 10:36 PM CT

An Alternative To Video Surveillance

An Alternative To Video Surveillance
Surveillance systems take on a new look with a technology developed by scientists at the Department of Energy's Oak Ridge National Laboratory.

The Laser-Based Item Monitoring System balances the need for high-resolution monitoring and personal safety with respect for confidentiality and personal privacy. This is particularly important today with heightened emphasis on security and privacy and is possible because the system does not use video.

"Our system is specifically designed to address surveillance requirements in places where video would be unacceptable because of the presence of proprietary information or other privacy concerns," said Pete Chiaro, a member of the Engineering Science & Technology Division.

Using low-cost reflective tags placed on objects, LBIMS maps the precise location of high-value items. The laser can scan a number of points per second and can detect small changes - less than a centimeter - in the reflected signal, meaning tampering can be immediately detected.

The precision of the system is made possible by a high-resolution two-axis laser scanner capable of looking at a 60-degree field of view in 0.0005-degree increments, dividing the field of view into more than 10 billion individual pointing locations. A camera with comparable resolution over the same field of view would require a 10,000-megapixel detector.........

Posted by: John      Read more         Source

May 14, 2007, 10:47 PM CT

Cluster makes a shocking discovery

Cluster makes a shocking discovery
The image shows a bow shock around the very young star, LL Ori.
ESA's Cluster was in the right place and time to make a shocking discovery. The four spacecraft encountered a shock wave that kept breaking and reforming - predicted only in theory.

On 24 January 2001, Cluster's spacecraft observed shock reformation in the Earth's magnetosphere, predicted only in theory, over 20 years ago. Cluster provided the first opportunity ever to observe such an event, the details of which have been published in a paper on 9 March this year.

The shock wave that sits above the Earth's surface is a natural phenomenon. It is located on the side facing the Sun, at approximately one quarter of the distance to the Moon, and is caused by the flow of electrically charged particles from the Sun.

This flow of electrically charged particles known as solar wind is emitted in a gusty manner by the Sun. When it collides with the Earth's magnetic field, it is abruptly slowed down and this causes a barrier of electrified gas, called the bow shock, to build up. It behaves in the same way as water being pushed out of the way by the front of a ship.

On 24 January 2001, the four Cluster spacecraft were flying at an approximate altitude of 105 000 kilometres, in tetrahedron formation. Each spacecraft was separated from the others by a distance of about 600 kilometres. With such a distance between them, as they approached the bow shock, researchers expected that every spacecraft would record a similar signature of the passage through this region.........

Posted by: Edwin      Read more         Source

May 9, 2007, 10:34 PM CT

Bridges that dance

Bridges that "dance" during earthquakes could be the safest and least expensive to build, retrofit and repair, as per earthquake engineers at the University at Buffalo and MCEER.

The scientists recently developed and successfully tested the first seismic design methodology for bridge towers that respond to ground motions by literally jumping a few inches off the ground.

The new methodology allows steel truss towers that support bridge decks to be built or retrofitted at far less expense than conventional approaches, where each leg of a bridge tower is strongly anchored to its footing.

The research is funded by the U.S. Federal Highway Administration.

The design recently underwent successful testing on a model truss tower that is 20 feet high and weighs nine tons.

Testing was conducted on a six-degrees-of-freedom shake table in UB's Structural Engineering and Earthquake Simulation Laboratory (SEESL). One of the world's most versatile earthquake engineering laboratories, it is a facility within the UB School of Engineering and Applied Sciences.

"Our approach is unconventional, counterintuitive," admits Michel Bruneau, Ph.D., director of MCEER and UB professor of civil, structural and environmental engineering, who developed the new approach with Michael Pollino, a doctoral candidate in the UB Department of Civil, Structural and Environmental Engineering.........

Posted by: Edwin      Read more         Source

Older Blog Entries   Older Blog Entries   1   2   3   4   5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52   53   54   55   56   57   58