Microbiologists Find A New Source Of Nitrogen Fixation
Posted: Friday, June 29, 2001
(BBC) The Microwave Anisotropy Probe (Map) will soon journey into deep space on a voyage to explore some of the mysteries of the Cosmos. With it astronomers hope to determine the content, shape, history, and the ultimate fate of the Universe.
The American space agency Nasa's $145m (£103m) spaceprobe will construct a full-sky picture of the oldest light in the Universe. It is designed to capture the afterglow of the Big Bang, which comes to us from all directions in space and from a time when the Universe was a very different place.
Map will look for faint patterns imprinted within this afterglow that carry the answers to many mysteries such as: What happened during the first instant after the Big Bang? How did the galaxies form? Will the Universe expand forever?
According to Professor Carlos Frenk of Durham University, UK: "This is the mission we have all been waiting for. It's better than anything we have had before. It will answer many questions and no doubt raise many more mysteries." More
Send page by E-Mail Cosmology: The Study of the Universe
Posted: Friday, June 29, 2001
Cosmology is the scientific study of the large scale properties of the Universe as a whole. It endeavors to use the scientific method to understand the origin, evolution and ultimate fate of the entire Universe. Like any field of science, cosmology involves the formation of theories or hypotheses about the universe which make specific predictions for phenomena that can be tested with observations. Depending on the outcome of the observations, the theories will need to be abandoned, revised or extended to accommodate the data. The prevailing theory about the origin and evolution of our Universe is the so-called Big Bang theory discussed at length in the pages linked below. This primer in cosmological concepts is organized as follows. The main concepts of the Big Bang theory are introduced in the first section with scant regard to actual observations. The second section discusses the classic tests of the Big Bang theory that make it so compelling as an apparently valid description of our universe. The third section discusses observations that highlight limitations of the Big Bang theory and point to a more detailed model of cosmology than the Big Bang theory alone provides. As discussed in the first section, the Big Bang theory predicts a range of possibilities for the structure and evolution of the universe. The final section discusses what constraints we can place on the nature of our universe based on current data, and indicates how MAP will further our understanding of cosmology. More
Send page by E-Mail Hint of Planet-Sized Drifters Bewilders Hubble Scientists
Posted: Thursday, June 28, 2001
Piercing the heart of a globular star cluster with its needle-sharp vision, NASA's Hubble Space Telescope has uncovered tantalizing clues to what could potentially be a strange and unexpected population of wandering, planet-sized objects.
In results published this week in NATURE, the international science journal, Kailash Sahu (Space Telescope Science Institute, Baltimore, MD) and colleagues report six unusual microlensing events inside the globular cluster M22.
Microlensing occurs when a background star brightens momentarily as a foreground object drifts by. The unusual objects thought to cause these events are far too dim to be seen directly, but instead were detected by the way their gravitational field amplifies light from a distant background star in the huge central bulge of our galaxy. Microlensing has been used before to search for low-mass objects in the disk and halo of our galaxy, but Hubble's sharp vision is essential to probe the interiors of globular clusters further.
From February 22 to June 15, 1999, Sahu and colleagues monitored 83,000 stars, detecting one clear microlensing event caused by a normal dwarf star in the cluster (about one tenth the mass of our Sun). As a result of gravitational lensing, the background star appeared to grow 10 times brighter and then returned to its normal brightness over a period of 18 days.
In addition to the microlensing event caused by the dwarf star, Sahu and his team recorded six even more interesting, unexpectedly brief events where a background star jumped in brightness by as much as a factor of two for less than 20 hours before dropping back to normal brightness. This means that the microlensing object must have been much smaller than a normal star.
These microlensing events were unusually brief, indicating that the mass of the intervening object could be as little as 80 times that of Earth. Objects this small have never before been detected by microlensing observations. If these results are confirmed by follow-up Hubble observations, the bodies would be the smallest celestial objects ever seen that are not orbiting any star.
So what are they? Theoretically they might be planets that were gravitationally torn away from parent stars in the cluster. However, they are estimated to make up as much as 10 percent of the cluster's mass -- too numerous to be wandering, "orphaned" planets.
The results are so surprising, the astronomers caution that these preliminary observations must be confirmed by follow-up Hubble observations. If verified, these dark denizens could yield new insights about how stars and planets formed in the early universe.
"Hubble's excellent sharpness allowed us to make this remarkable new type of observation, successfully demonstrating our ability to see very small objects," says Sahu. "This holds tremendous potential for further searches for dark, low-mass objects."
"Since we know that globular clusters like M22 are very old, this result opens new and exciting opportunities for the discovery and study of planet-like objects that formed in the early universe," adds co-investigator Nino Panagia (European Space Agency and Space Telescope Science Institute).
"This initial observation shows that our microlensing method works beautifully," states co-investigator Mario Livio (Space Telescope Science Institute).
As microlensing events are brief, unpredictable and rare, astronomers improve their chances of observing one by looking at many stars at once -- much like a person buying several lottery tickets at once. Most microlensing searches have been aimed at the central bulge of our galaxy or out towards the Magellanic Clouds -- the densest observable regions of stars in the sky. In general these surveys cover areas of sky larger than the full Moon and look for foreground objects lying somewhere between us and the background population of stars.
Sahu and his team took advantage of Hubble's superb resolution and narrow field of view to aim the telescope directly through the center of a globular star cluster lying between Earth and the galactic bulge. This gave the team a very dense stellar region to probe for drifting low-mass foreground objects and a very rich background field of stars to be lensed. Only Hubble's resolution is sharp enough to actually peer through the crowded center of the cluster and see the far more distant stars in the galactic bulge. As the lensing objects were part of the cluster, the astronomers also had an accurate distance (8,500 light-years) and velocity for these objects.
In a normal lensing event, a background star brightens and dims for a length of time depending on the mass of the lensing body. The short, "spurious" events seen by the team are shorter than the interval between the Hubble observations, leading to an upper estimate for the mass of an object of one quarter Jupiter's mass.
To confirm these extraordinary, but tentative results, Sahu and colleagues next plan to monitor the center of the globular cluster continuously over a seven-day interval. They expect to detect 10 to 25 short-duration microlensing events, which will be well-sampled enough to yield direct measurements of the true masses of the small bodies.
This release is issued jointly by NASA and ESA.
Editor's Note: The original news release can be found at
Send page by E-Mail Scientists find firefly 'switch'
Posted: Thursday, June 28, 2001
(BBC) Scientists have found the "switch" that allows a firefly to light up its body. The beetle flashes the "lantern" on its abdomen to attract a mate. Researchers have long understood how the light is generated but the control mechanism used by the insect has been a mystery.
Now, a US team has been able to show that the simple molecule nitric oxide (NO) acts as the on-off "button".
It is just one more example of the prominent role played by NO in biochemistry. In humans, the molecule is crucial to the dilation of blood vessels and the signalling that goes on between neurons in the brain.
Its part in assisting men achieve erection has been exploited by the modern impotence drugs like Viagra. More
Send page by E-Mail Study Stirs Old Debate about Galaxies
Posted: Tuesday, June 26, 2001
(Headlines@Hopkins) Using a technique that peeks over obscuring rings of dust and gas and into the hearts of distant galaxies, a researcher has found evidence suggesting that as many as half of the bright, active galaxies known as Seyfert 2 galaxies may have significantly less active central black holes.
Seyfert galaxies are among the most important sources of information astronomers have on the evolution of galaxies, and the supermassive black holes at their centers are increasingly thought to be the "engines" driving galaxy formation, so a change in the activity levels of the central black holes in some Seyfert 2 galaxies could have big implications.
However, Hien D. Tran, the author of the new study, acknowledges that such a change may still be a long way off. He feels his data "strongly suggest" that some central black holes in Seyfert 2 galaxies are less active than previously thought, but admits that many astronomers will debate his interpretation, and that his theory can only be proven through follow-up observations. "This is to be expected for something that questions what has been the standard paradigm for such a long time," says Tran, a research scientist in The Krieger School of Arts and Sciences at The Johns Hopkins University. Tran's study was published in the June 10 issue of Astrophysical Journal Letters.
"I think if you took a survey of astronomers today, most of them would say the signal of the very active supermassive central black hole is in there in those galaxies, you just haven't looked hard enough," says Tim Heckman, a professor of astronomy at Hopkins who has reviewed Tran's paper. "It's going to be hard to prove the negative."
Seyfert galaxies and astronomers have always been a little bit like the proverbial blind men and the elephant. Stuck with extremely limited points-of-view of an elephant, the blind men came away with very different impressions of what it was.
Astronomers aren't blind, but they are limited to observing galaxies from Earth or its vicinity, and for an object as big as a galaxy, that amounts to a single tightly restricted perspective. Studying more than one example of a particular type of galaxy can yield different points of view, but researchers have to be sure the different examples they use are the same type of galaxy.
That's where the distinctive features of a Seyfert galaxy can increase the challenge. The characteristic trait of a Seyfert galaxy is a blisteringly bright fountain of energetic emissions from the central black hole. Astronomers currently believe a torus- or doughnut-shaped cloud of gas and dust surrounds the central black hole in Seyfert galaxies, and that this cloud shapes the fountain by only allowing the intense radiation from the black hole to erupt from the cloud's dust-free central hole.
Seyfert 1 galaxies are oriented so that the opening of the torus points toward Earth, allowing a direct view of activity in the galactic nucleus. However, Seyfert 2 galaxies are oriented so that the opening of the torus is not visible from Earth, and this makes them look different to astronomers.
Astronomers first came to think of Seyfert galaxies as one type of galaxy seen from different views in 1983, when Tran's future mentor, Joseph Miller of the University of California-Santa Cruz and his student Robert Antonucci, now at the University of California-Santa Barbara, proposed what would become known as the unified model of Seyfert galaxies.
Miller and Antonucci based their unified model, which included the concept of a torus of gas and dust surrounding the central black hole, on Seyferts data gathered through a technique known as spectropolarimetry.
"Spectropolarimetry lets us detect how much of the light from a source comes directly from the source, and how much of it is reflected light from other sources that may be hidden," says Tran. "Any time light is reflected, it becomes polarized, and this technique lets us detect that."
Feeling that a definitive test of whether the unified model applied to all Seyfert galaxies was lacking, Tran set out to use spectropolarimetry to conduct a study of a large number of Seyfert 2 galaxies. With funding from NASA, the National Science Foundation, and the Department of Energy, Tran spent seven years either observing directly or analyzing previously acquired data from 50 Seyfert 2 galaxies.
Aaron Barth, a research fellow at the Harvard- Smithsonian Center for Astrophysics, reviewed Tran's study for publication and called it "the largest survey of its kind to date."
In about half of the Seyfert 2 galaxies Tran studied, he could clearly detect reflected light with spectroscopic features similar to those seen in the center of Seyfert 1 galaxies. Although the fountain of radiation from the area around the central black hole in these galaxies points in a direction that makes it hard to see from Earth, enough of the black hole's spectral signature was reflected by material around the galaxy for Tran to detect it.
"The other half of these galaxies, though, don't seem to fit the model," says Tran. "The signature of the central black hole's activity doesn't appear even when you observe the galaxy in polarized light." Tran has tentatively decided to call these "pure S2s," or pure Seyfert 2 galaxies.
To begin checking if anomalous factors in individual galaxies might be obscuring the central black hole's spectroscopic signature, Tran analyzed several other observable characteristics, and once again found that the pure S2s seemed unusual.
"For example, when you plot the luminosity of these galaxies in radio wavelengths versus their flux ratio in the infrared, you can see that the pure S2s appear on average to be cooler and less luminous in radio waves," Tran says. "This correlates well with the idea that pure S2s may have a less active central black hole. Less active central black holes should heat up the surrounding gas and dust less than active black holes." There are still a number of additional possible explanations to consider, though.
"Starbursts, which are regions of intense star formation, may be muddling the picture," says Heckman, who suggests using X-ray observatories to look beyond the gas and dust to get a better picture of the galaxies in question, perhaps providing more clues as to whether they are genuinely different.
Editor's Note: The original news release can be found at
Send page by E-Mail Jupiter Particles' Escape Route Found
Posted: Monday, June 25, 2001
(NASA) Jupiter's magnetosphere, an ionized-gas bubble encasing the planet, is lopsided and leaky, with an unexpected abundance of high-energy particles bleeding out of one side, according to recent measurements by NASA's Cassini spacecraft.
Those escaping electrons and ions might be riding magnetic field lines that are attached to Jupiter at one end and waving loose on the other, unlike more common lines that loop between Jupiter's north and south hemispheres closer to the planet.
Deciphering the process could advance understanding of the protective magnetic field around Earth, as well as the much greater one around Jupiter, said Dr. Dennis Matson, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. Jupiter's magnetosphere is so vast that if it shined at wavelengths visible to the eye, it would appear from Earth to be two to three times wider than the disc of the Sun, even though it is more than four times as far away.
"The dusk flank of Jupiter's magnetosphere is a surprising contrast to the dawn flank," said Dr. Stamatios (Tom) Krimigis, a Cassini scientist who heads the space department of the Johns Hopkins University's Applied Physics Laboratory, Laurel, Md. Cassini spent most of January and February skating along the magnetosphere's dusk flank, which is on the side of the planet turning away from the Sun. Other spacecraft, such as Voyager, previously sampled the opposite flank, corresponding to Jupiter's dawn side.
Cassini was flying past Jupiter last winter for a gravity boost to reach Saturn. Researchers grabbed the opportunity to study the giant planet from different vantage points by also using NASA's Galileo spacecraft, which is orbiting Jupiter, plus other spacecraft and ground-based telescopes, in coordination with Cassini's Jupiter observations. More than 20 scientists are presenting some preliminary results from that campaign during meetings of the American Geophysical Union in Boston this week.
The electrons Cassini caught escaping may answer a puzzle. Scientists had figured that some electrons were getting out of Jupiter's magnetosphere, sometimes even reaching Earth's neighborhood, but they didn't know the primary route. "It appears we've found where they're coming from," Krimigis said.
Dr. John Clarke of the University of Michigan, Ann Arbor, used a movie taken by NASA's Hubble Space Telescope of Jupiter's auroras while Cassini and Galileo were monitoring Jupiter's magnetosphere and the solar wind, a flow of particles speeding away from the Sun and deflected around the magnetic fields of planets. Clarke said that movements of the auroral glows indicate which features in them are linked to the magnetosphere, because they follow the rotation of the magnetic field, and which are linked to solar-wind effects, because their positions stay oriented with respect to the direction toward the Sun.
The timing and location of one patch of auroral brightening captured by Hubble corresponded to a pulse of electrons detected by Galileo in the magnetosphere. That pulse appears to have been a type that also occurs in Earth's magnetosphere, said Dr. Barry Mauk of Johns Hopkins University's Applied Physics Lab, Laurel, Md., team member on the energetic particle detector experiment on Galileo. "Energy builds up in the system, pulling the magnetic field lines outward like rubber bands, but eventually these rubber bands can snap back toward the planet," Mauk said. The snapping back brings an injection of high-energy electrons, he said.
Having Galileo inside Jupiter's magnetosphere at the same time Cassini was just outside of it in the solar wind gave scientists a chance to see whether such injections are triggered by fluctuations in the solar wind, as can happen at Earth. No obvious solar wind event corresponded to the injections seen by Galileo. "It appears injections can happen without being externally stimulated," Mauk said.
The solar wind does appear to have tipped features of Jupiter's magnetosphere northward part of the time during the Galileo and Cassini joint studies, said Dr. Margaret Kivelson of the University of California, Los Angeles, principal investigator for Galileo's magnetometer instrument. That gave Galileo a taste of conditions that are usually farther south, and it found that magnetic field lines there twist differently than they do near the equatorial plane.
"It's as if a hula dancer had a skirt made of ribbons that fly out as she twirls, but at one layer the ribbons twirl in one direction and at a different layer they twirl in the other direction," Kivelson said.
Jupiter's moon Io has its own auroras, which Cassini captured in images taken while Io was in Jupiter's shadow. "We could see that bright blue emissions near the equator move around in a way that tells us their source," said Dr. Paul Geissler of the University of Arizona, Tucson. The electron flow causing gases to glow there comes from an electrical current running between Io and Jupiter, he said. A new color movie clip of the images is available at http://www.jpl.nasa.gov/images/jupiter and at http://ciclops.lpl.arizona.edu/.
In addition, Io's volcanoes put out about a ton per second of gases such as oxygen and sulfur. These are spun out of Jupiter's magnetosphere and form a "Jovian nebula" that extends tens of millions of kilometers or miles away from Jupiter, Krimigis found with one of Cassini's sensors. "We have even detected sulfur dioxide a long way from Jupiter," he said.
More information about the joint Cassini and Galileo studies of Jupiter is available at http://www.jpl.nasa.gov/jupiterflyby . JPL, a division of the California Institute of Technology in Pasadena, manages Cassini and Galileo for NASA's Office of Space Science, Washington, D.C. Cassini is a joint project of NASA and the European Space Agency. The Space Telescope Science Institute in Baltimore, Md., manages Hubble.
Editor's Note: The original news release can be found at http://www.jpl.nasa.gov/releases/2001/agujup0531.html
Send page by E-Mail Natural "Lava Lamp" Draws Sea Floor Patterns
Posted: Friday, June 22, 2001
University Of California, Davis (http://www-news.ucdavis.edu/PubComm/)
Giant V-shaped ridges on the floor of the Atlantic Ocean are explained by a new theory developed by University of California, Davis, geologist Garrett Ito.
The V-shaped ridges, which are hundreds of miles long, lie across the Reykjanes ridge, a line running south from Iceland where the continental plates of America and Europe are slowly drifting apart. Geologists know that Iceland is a tectonic "hot spot" where molten rock rises toward the surface, but the origin of the V-shaped ridges had puzzled geologists since their discovery 30 years ago, Ito said.
Ito used a computer model to show that a pulsing plume of molten rock, like a slow motion lava lamp beneath Iceland, could account for the phenomenon. Deep in the earth, the rock contains water which makes it more fluid. As it rises to the surface, the rock begins to melt, forcing out the water and making it stiff, Ito said. This sets an upper boundary for the partially molten rock, forcing it to flow sideways.
"It's a bit like pouring batter onto a hot griddle. As it hits the griddle it sets, and has to run sideways," said UC Davis geologist Charles Lesher, who is not an author on the paper.
The blobs of partially molten rock then flow along the mid-Atlantic ridge, about 90 miles (145 kilometers) below the surface. The molten rock slowly percolates upwards and eventually reaches the surface, where it "freezes" into solid crust. As the ridge pulls apart, it draws out the ends of the "V."
"This provides an explanation for the V-shaped ridges that links the surface features to the Iceland hotspot," said Lesher.
The study was published in the June 7 issue of Nature.
Send page by E-Mail Current changes could cool UK
Posted: Friday, June 22, 2001
(BBC) Scientists say they have found further evidence that the currents in the North Atlantic are changing. They say the amount of cold water flowing south from the Arctic has fallen significantly in the last 50 years.
This could affect the Gulf Stream, which helps to give the UK and north west Europe their temperate climate. One estimate suggests that without the Gulf Stream winter temperatures in the UK could fall by an average of 11 degrees C, giving parts of the country the same temperatures as Svalbard, the Norwegian archipelago 750 miles from the North Pole.
The scientists believe it could be another effect of the changing climate.
The scientists, from the Faroe Islands, Norway and the UK, report their findings in the magazine Nature. They measured the flow of cold, dense Arctic water across the Faroe Bank channel, which lies between the Faroes and Shetland, the island group north of the Scottish mainland. More
Send page by E-Mail Massive Star Clusters Swaddled In Huge Cocoons During Infancy
Posted: Friday, June 22, 2001
University Of Colorado At Boulder (http://www.colorado.edu/)
New observations with the Gemini North Telescope in Hawaii indicate three of the youngest massive star clusters yet detected each are swaddled in dust cocoons at least 600 trillion miles across, providing new clues to the evolution of the early universe.
Globular star clusters are among the most ancient objects in the universe, forming about the same time as the first galaxies, said Kelsey Johnson, a doctoral student at the University of Colorado at Boulder. "While their formation remains somewhat of a mystery, they clearly require conditions that are uncommon in the universe today."
Astronomers estimate the baby globular star clusters observed in the starburst galaxy Henize 2-10 are less than 1 million years old – analogous to the first day of life for a human. "If we can study objects like globular clusters as they are forming, then we should be able to learn more about the conditions in the early universe," said Johnson, a doctoral student in the astrophysical and planetary sciences department and a researcher at JILA.
Johnson and her collaborators Bill Vacca of the Max Planck Institute in Garching, Germany, and CU-Boulder Professor Peter Conti presented a paper on the subject at 197th meeting of the American Astronomical Society June 3-7 in Pasadena.
The birthing massive star clusters were first observed two years ago by Johnson and University of Wisconsin, Madison astronomer Henry Kobulnicky with the Very Large Array Telescope in Socorro, N.M.
The new images taken by the three astronomers using Gemini North revealed three infrared objects deep within the heart of the Henize 2-10 galaxy. Because the infrared emissions from the three infant star clusters comprise the bulk of all wavelength emissions, Johnson and her colleagues believe the three clusters must be "the engine" that powers most of the energy radiated by the galaxy.
Johnson said the Gemini North telescope observations indicated the baby star clusters were emitting between 60 percent and 100 percent of the infrared emissions emanating from Henize 2-10. "Given the vigorous star formation throughout Henize 2-10 as seen in optical light, it is remarkable that only a handful of these objects could be responsible for all the infrared light we see," she said.
The youngest phases of massive star clusters require behemoth "birthing clouds" of dust, which are extremely efficient at absorbing optical and ultraviolet light and "re-radiating it as infrared light," said Vacca. The researchers estimated the temperature of the dust shells surrounding the infant clusters at a minus 200 degrees Fahrenheit.
"This may sound cold, but compared to the rest of the universe – which is just above absolute zero due to the cosmic microwave background – the temperatures of the dust shells surrounding infant stars really are quite balmy."
Henize 2-10 is located some 32 million light-years from Earth in the constellation Pyxsis and contains several star clusters harboring as many as a million stars each. Packed into a relatively small area of space, each cluster is believed to evolve over billions of years into globular clusters like those orbiting the Milky Way.
Such "super star clusters" in galaxies like Henize 2-10 seem to undergo a violent, short-lived phase, producing prolific numbers of stars in specific star-birth regions at extremely rapid rates. It is not known exactly what triggers these outbursts, but it appears that a catastrophic event such as the collision or merger of two galaxies is required, said Vacca.
Galaxies like Henize 2-10 are known to radiate as much as 10 times more energy in the infrared than in optical and UV wavelengths, said Vacca. This suggests there is not only a large amount of newly formed stars and star clusters present, but also a vast amount of dust in these massive objects.
Located on Mauna Kea, The Gemini North Telescope has an 8.1-meter mirror and sophisticated optics that make it the most powerful ground-based telescope in the world. An identical observatory, the Gemini South Telescope, is now being completed in Chile.
The two identical Gemini telescopes are an international project funded in the United States by the National Science Foundation as well as funds from the United Kingdom, Canada, Chile, Australia, Argentina and Brazil.
Send page by E-Mail Researchers to Find The "North Pole" Of The Molecular World
Posted: Friday, June 22, 2001
University Of Rochester (http://www.rochester.edu)
Researchers have devised a method to determine the alignment of a molecule's axis, the "poles" that govern how a molecule will interact with others. The advancement will help scientists and engineers predict the ways that atoms and molecules exchange energy, possibly enhancing solar energy devices or helping biochemists better understand proteins. The research, appearing in the June 4 issue of Physical Review Letters, shows how a tightly-focused laser employing a new kind of polarization can produce valuable images of individual molecules in three dimensions.
The new method takes a snapshot of a phenomenon called the "molecular dipole moment." This "moment" is an axis that runs through the molecule like a north and south pole, along which energy is emitted and absorbed. If two molecules are positioned so that their respective poles align, they are more likely to exchange energy. If they are completely misaligned, then an interaction is more difficult. Someday, researchers hope to control the alignment to direct chemical reactions at the atomic level.
"By imaging the dipole movement of certain molecules we can see exactly how certain chemical reactions happen," says Lukas Novotny, assistant professor of optics at the University of Rochester. "We're working now with biochemists to understand how various proteins in the body form."
Proteins fold when they form, but monitoring their folding is a tricky business that the Rochester team's method can help clarify. To watch the folding process, researchers place two marker molecules at each end of the protein-one marker emits green light when stimulated, and the other emits red. One marker (the green one) is charged with energy so that it emits its light. When the protein folds itself and brings these two markers together like a gymnast touching her toes, the green marker gives some of its energy to the other, which then glows, causing a change in the overall color of light emitted from the protein. Exactly when this energy exchange takes place, however, depends on how far apart the marker molecules are and how their "poles" are oriented. Biochemists will now be able to know exactly what the markers' orientations are, and so know exactly how far the protein has folded when the emitted light changes. This puts a powerful new tool in the hands of scientists investigating cellular processes.
Determining the north pole of an atom required a new class of light polarization, the development of which was pioneered by Thomas Brown, associate professor of optics at the University. Regular light has linear polarization, which means it essentially vibrates within a plane. The molecule-imaging method, however, uses radial polarization, where the vibration moves in several planes radiating outward from the light beam. By converting regular laser light to radial-polarized light and tightly focusing the laser beam, the team can create a tiny electric field that is of equal strength in all three dimensions, thanks to the radial polarization. The team then scans the beam along the molecule in all directions until one of the radial planes lines up with the north or south pole, and the atom absorbs the energy. A slight burst of fluorescence tells the team when they've hit their mark, and they can determine at exactly what angle the pole is oriented.
Novotny sees other applications for molecular dipole moments. "Cells in the body communicate through proteins located in their membranes. During an exchange of information, the shape of the proteins changes. By attaching molecular markers to the protein and monitoring their orientation and position, we should be able to better understand communication between cells." Tracking the dipole moments might also shed light on how cancer cells grow in colonies. Novotny predicts that someday molecular dipole moments may be not just ascertained but controlled, allowing for quick, custom-made molecule alignment, or even data storage, since the orientation of the dipole moment could stand for a one or zero.
Joining Novotny and Brown in the research are postdoctoral research associate Achim Hartschuh and graduate students Michael Beversluis and Kathleen Youngworth of the University. The work was funded by the National Science Foundation. Original Article
Send page by E-Mail Very Small Galactic Bulge
Posted: Thursday, June 21, 2001
Very Small Galactic Bulge Could Change Ideas Of Galaxy Formation
COLUMBUS, Ohio -- The nearby galaxy M33 has a much smaller central bulge than astronomers had previously thought -- or perhaps no bulge at all, according to astronomers at Ohio State University. The finding may expand current theories of how spiral galaxies form.
Galaxies such as M33 are called spiral galaxies because pinwheel-shaped arms of gas, dust, and stars extend directly out from a spherical nucleus of stars at the center, giving the galaxy a flattened disk shape. The spherical nucleus is called a bulge, because it normally bulges out from the disk.
Using some of the first images from the 8-meter Gemini North telescope on Mauna Kea in Hawaii, the Ohio State astronomers examined the innermost 80 parsecs (1520 trillion miles) of M33 -- where other astronomers previously claimed finding the bulge of this spiral galaxy. They presented their results June 4 at the meeting of the American Astronomical Society in Pasadena.
Instead of the old stars that normally populate a galactic bulge, the astronomers found evidence of both young and intermediate-age stars. The density of stars in the region more closely resembles a galactic disk than a bulge -- as if the disk extended to the very core of M33, said Andrew Stephens, doctoral candidate in Ohio State's Department of Astronomy. Stephens did the work with Jay Frogel, professor of astronomy.
"This finding makes us question the role of a bulge in spiral galaxy formation," Stephens said. "If M33 doesn't have a bulge at all, then how exactly did it form? If it has young stars in its bulge, what triggered their formation?"
While a typical galactic disk is made up of stars of all ages, the bulge normally contains old stars which date from the time the galaxy formed. This is one reason that studying bulges can tell astronomers about how galaxies form and evolve, Stephens explained.
According to current theory, spiral galaxies begin as a giant rotating mass of gas and dust, which starts out in a roughly spherical shape before the edges flatten out into a disk and create the spiral arms. The original spherical shape lives on in an outer region of a galaxy known as the "halo" and, to a lesser extent, in the bulge.
With the aid of "Hokupa`a", an adaptive optics instrument on loan to Gemini from the University of Hawaii Institute for Astronomy, the Ohio State astronomers recorded images of M33 in three infrared wavelengths and combined them to form a "color" image. The adaptive optics system corrects for turbulence in the Earth's atmosphere, and allows astronomers to achieve much better resolution than was previously available from the ground.
These high-resolution images revealed bright red stars indicative of an intermediate-age population, and even bright blue young stars, both of which should not be present in a bulge, Stephens said.
Previous attempts to study the bulge at the center of M33 had yielded contradictory results, Stephens said. Spectroscopic studies indicated the presence of a young population, but ground-based images didn't have enough resolution to distinguish between the many different types of stars crowded into the center of the galaxy.
Seven countries -- Argentina, Australia, Brazil, Canada, Chile, the United Kingdom, and the United States -- share financing for the $192-million Gemini project. The Association of Universities for Research in Astronomy, Inc. (AURA) manages the Gemini Observatory under a cooperative agreement with the National Science Foundation. Ohio State is a member of AURA.
Editor's Note: The original news release can be found at
Send page by E-Mail Evidence Of Ancient El Ninos And Cultural Development
Posted: Thursday, June 21, 2001
(Science Daily) In the July issue of the journal Geology, a team of researchers has suggested that the climate phenomenon known as El Nino has been a contributing factor in the rise and fall of ancient civilizations in Peru. Using archeological evidence from sites along the Peruvian coast, scientists from the University of Maine, Yale University, University of Pittsburgh and University of Miami suggest that the fate of organized Peruvian societies may be related to environmental changes caused by flood cycles starting about 5,000 years ago.
Daniel Sandweiss of the UMaine Department of Anthropology and Institute for Quaternary and Climate Studies (IQCS), is lead author of the article which describes changes in mollusk assemblages in midden heaps. Co-authors are Kirk Maasch of the UMaine Dept. of Geological Sciences and IQCS, Richard L. Burger of Yale University, James B. Richardson III and Harold B. Rollins of the University of Pittsburgh and Amy Clement of the University of Miami.
"We found that there was a change in the frequency of El Nino events about 3,000 years ago and that this correlates in time with cultural change," says Sandweiss.
Other researchers have reported similar evidence from Central and North America, Greenland and the Middle East that suggests a relationship between climate and culture. "We don't argue that climate is the driving force behind cultural development, but the evidence points to a strong contributory role," says Sandweiss. More
Send page by E-Mail Failure At Nonconscious Goals "Mystery Moods"
Posted: Thursday, June 21, 2001
Failure At Nonconscious Goals Explains Negative "Mystery Moods"
COLUMBUS, Ohio - Have you ever been in a bad mood that you couldn't explain and wondered what put you in a funk?
A researcher at Ohio State University found that such negative "mystery moods" can occur when people fail at a goal that they didn't even know they had.
Tanya Chartrand, assistant professor of psychology, said such nonconscious goals can have significant effects on how we feel and act, and even on how well we achieve other goals.
"If you succeed at a goal you didn't know you had, you're in a good mood and don't know why," Chartrand said. "But if you fail at a nonconscious goal, you're put into this negative, mystery mood."
Chartrand discussed her recent research June 15 in Toronto at the annual meeting of the American Psychological Society.
Nonconscious goals are goals that people have frequently and consistently chosen in particular situations in the past - so much so that they eventually become triggered automatically in those same environments without their conscious thought or even intent, Chartrand explained.
For example, young people who begin attending parties may start by very consciously thinking about how to best present themselves to others, and carefully monitor how they act and what they say. Over time, the features of the party environment become linked in memory with the goals of presenting themselves well. In time, the goals become nonconscious and are triggered automatically every time they go to a party.
Eventually, Chartrand said, they may not even realize they have a goal when they attend a party - but they do.
Chartrand has conducted a variety of studies examining what happens to people when they succeed or fail at these nonconscious goals.
In one study Chartrand conducted, 109 college students were given a scrambled sentence task in which they had to rearrange a series of words to make a sentence. In some cases, the students were "primed" to have a success goal by using words like "strive," "achieve," and "succeed." Other students were given neutral words that would not inspire an achievement goal.
Next, the same students were given a timed anagram task in which they had to rearrange the letters of words to create new words. The students were given either an easy anagram task in which success was assured, or a hard task that was impossible to successfully complete.
All the students then completed a questionnaire that measured their moods.
Results showed that, for participants primed with an achievement goal, those who were given the easy test reported being in a better mood than those who were given the hard test.
But, for participants who were not primed to have an achievement goal, there were no mood differences between those who had the easy test and those who had the hard test.
"We set up the experiment so some participants would have a goal of succeeding at the anagram task - even though they didn't consciously know they had such a goal," Chartrand said. "For these participants, their mood was affected by whether they succeeded or failed. For the other participants, success or failure didn't have an impact on their mood."
In a second study, Chartrand found that failing at nonconscious goals not only had negative affects on mood - it also hurt performance. In this study, participants who were primed to have an achievement goal and then failed at an anagram task did worse on a standardized verbal test than did participants who succeeded at the task. Other studies by Chartrand suggest, though, that participants who fail at nonconscious goals may sometimes be inspired to do better on subsequent performance tests.
"The key is that nonconscious goals can affect both mood and performance," she said.
Chartrand said other research she has conducted shows that people who fail at nonconscious goals try to bolster their self-esteem by stereotyping or disparaging others. "If you fail at a conscious goal, you know why you're in a bad mood. But if you fail at a nonconscious goal you don't know why you're in this mystery mood and you're more likely to stereotype others to help enhance your self-esteem."
Chartrand said nonconscious goals play an important role in everyday life. For example, many students may have nonconscious achievement goals that affect how they act in school. Employees may have similar goals at work.
"Nonconscious goal pursuit is incredibly pervasive because it saves us cognitive resources," she said. "If we constantly had to think about what we want to accomplish in every particular situation, we wouldn't be able to do anything else.
"We are succeeding and failing at these nonconscious goals all the time," she said. "Research is beginning to show how this affects our moods, the way we perform, and the judgments we make about others. It's incredibly important."
Editor's Note: The original news release can be found at
Send page by E-Mail Human Evolution
Posted: Thursday, June 21, 2001
If you want to learn more about evolution in general, and human evolution, in particular, explore evidence from comparative genetics, anatomy, and the fossil record in some of the following places. More
Send page by E-Mail How cells make protein molecules
Posted: Wednesday, June 20, 2001
One of the most important tasks of any living cell is making the protein molecules that form its internal structures, trigger important chemical reactions, and fill many other roles. How are protein molecules made?
Protein molecules are assembled from simple molecules called amino acids by molecular machines called ribosomes, themselves made largely out of protein. A ribosome starts making a protein by catching the end of a molecule called messenger RNA, which contains the coded instructions to make the protein.
The messenger RNA (which was created by reading DNA in the cell's nucleus) feeds through the ribosome like a ribbon, and as it feeds through its code is read. The ribosome recognizes the pattern of code, and adds the appropriate amino acids to the partially completed protein. When the protein molecule is finished, it is released and the ribosome can begin building another one. More
Send page by E-Mail The Endocrine System
Posted: Wednesday, June 20, 2001
The endocrine system is made up of specialized glands that have the ability to produce chemicals called hormones. Hormones go into and are transported by the blood to other parts of the body where they control various functions. The endocrine system is much like the nervous system in its ability to control functioning of different areas of the body (target organs). More
Send page by E-Mail Articles and links about Chemistry
Posted: Wednesday, June 20, 2001
The word Chemistry is a combination of two words CHEM, the ancient name for Egypt, which ment BLACK, referring to the study of MELANIN, and, ISTRY which means 'the study of '. The root of this science like all other sciences is African. More
Send page by E-Mail The Composition of physical Life
Posted: Wednesday, June 20, 2001
All living things carry a detailed set of instructions carrying the information necessary to develop and maintain physical life. This living blueprint is present in the form of a double stranded chemical called DNA. More
Send page by E-Mail Russian Jewish Genetics
Posted: Wednesday, June 20, 2001
This page challenges the notion that everything about Jewish genetics has already been determined from the preliminary, incomplete studies that have been conducted since the 1970s, and shows how there is considerable disagreement among geneticists, anthropologists, and scholars in interpreting what the results of various genetic studies mean. This page presents all points of view. At the present time, it appears that Eastern European Jews have a significant Eastern Mediterranean element which manifests itself in a close relationship with Lebanese, Syrian, and Anatolian Turkish peoples. At the same time, there are clear traces of European and Khazar ancestry among European Jews. More
Send page by E-Mail The Holocene: The last 11,000 years
Posted: Wednesday, June 20, 2001
To observe a Holocene environment, simply look around you! The Holocene is the name given to the last 11,000 years of the Earth's history -- the time since the end of the last major glacial epoch, or "ice age." Since then, there have been small-scale climate shifts -- notably the "Little Ice Age" between about 1200 and 1700 A.D. -- but in general, the Holocene has been a relatively warm period in between ice ages. More
Send page by E-Mail The Universe: Still Boggling the Minds of 'Finite Creatures'
Posted: Wednesday, June 20, 2001
"As much as we have progressed in science, we are still finite creatures with limited conceptual abilities and imperfect observational tools," said James Sweitzer, director of astrophysics education at the American Museum of Natural History's Rose Center for Earth and Space.
Humbling thought. But add one thing: We are highly curious creatures prone to speculation.
That in mind, we wanted to at least pose the questions that we suspect swirl through the minds of all who have ever been curious, who have ever looked up on a dark night and simply wondered.
How old is the universe? Does it have an edge? And, c'mon, truthfully -- How could it all have begun in some "Big Bang" that originated in a spot smaller than the dots under all these questions marks?
For answers, we pestered Sweitzer and Mario Livio, head of the science division at the Space Telescope Science Institute in Baltimore.
What a cosmic can of worms. Turns out even the word "universe" is elusive, having three meanings (two of which depend on whether or not you hit the shift key). So we start with the basics. More
Send page by E-Mail Galactic Center Bathed In High-Energy X-Rays
Posted: Wednesday, June 20, 2001
Star Factory Near Galactic Center Bathed In High-Energy X-Rays
Near the crowded core of the Milky Way galaxy, where stars are so plentiful and shine so brightly that planets there would never experience nighttime, astronomers have found a new phenomenon: a cauldron of 60-million degree gas enveloping a cluster of young stars.
Professor Farhad Zadeh of Northwestern University, Evanston, IL, and his collaborators used NASA's Chandra X-ray Observatory to trace the gas around the Arches cluster, a well-studied region of star formation that is home to some of our galaxy's largest and youngest stars.
"This is the first time we have seen a young cluster of stars surrounded by such a halo of high-energy X-rays," said Zadeh in a news conference at the American Astronomical Society in Pasadena, CA. "This supports theoretical predictions that stellar winds from massive stars can collide with each other and generate very hot gas."
Massive stars, newborn stars and stellar winds have long been known to emit X-rays. The Chandra results are significant because they identify this new mechanism of stellar winds colliding to generate X-rays as energetic as those seen in distant starburst galaxies, which are known for their furious pace of star production.
The Arches cluster is about 25,000 light-years from Earth and only about one-to-two million years old. It is also less than 100 light-years from what is thought to be a supermassive black hole in the center of our galaxy. The cluster contains 150 hot, young stars, known as "O" stars, concentrated within a diameter of one light-year, making it the most compact cluster known in the Milky Way galaxy.
The density of stars makes the region in and around the Arches cluster a microcosm of what is likely occurring in starburst galaxies.
"The Arches cluster is one of the best 'local' analogues of starburst galaxies -- the most prodigious stellar nurseries known," said Casey Law of the Harvard-Smithsonian Center for Astrophysics, Cambridge, MA. "Yet the Arches cluster is in our backyard, not millions of light-years away."
Starburst galaxies are known for creating huge hot bubbles of gas that escape from the galaxy. In a similar way, Chandra observations of the Arches clusters may provide clues to the origin of a much larger cloud of hot gas known to exist in the galaxy's center.
"Our data suggest that the gas within the Arches cluster may get so hot that it escapes from the cluster," said Cornelia Lang of the University of Massachusetts, Amherst. "The Arches and other clusters like it may contribute to the reservoir of mysterious hot gas long observed near the Milky Way."
Zadeh and his collaborators intend to search for X-ray emissions from other clusters of stars near the galactic center and compare this to newer, longer Chandra observations of the Arches cluster.
Chandra observed the Arches cluster region with its Advanced CCD Imaging Spectrometer (ACIS). The research team for this investigation included Casey Law and Antonella Fruscione from the Harvard-Smithsonian Center for Astrophysics; Cornelia Lang and Daniel Wang from University of Massachusetts; Mark Wardle of the University of Sydney, Australia; and Angela Cotera from University of Arizona, Tucson.
The ACIS X-ray camera was developed for NASA by The Pennsylvania State University, University Park, and the Massachusetts Institute of Technology, Cambridge. NASA's Marshall Space Flight Center in Huntsville, AL, manages the Chandra program for the Office of Space Science, Washington, DC. TRW, Inc., Redondo Beach, CA, is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center, Cambridge, MA, controls science and flight operations.
Images associated with this release are available at:
http://chandra.harvard.edu and http://chandra.nasa.gov
Send page by E-Mail Missing Solar Neutrinos Revealed
Posted: Monday, June 18, 2001
First Results from the (SNO) Sudbury Neutrino Observatory Explain the Missing Solar Neutrinos and Reveal New Neutrino Properties
Physicists from Canada, the UK and the US are today announcing that their first results provide a solution to a 30-year old mystery- the puzzle of the missing solar neutrinos. The Sudbury Neutrino Observatory (SNO) finds that the solution lies not with the Sun, but with the neutrinos, which change as they travel from the core of the Sun to the Earth.
Neutrinos are elementary particles of matter with no electric charge and very little mass. There are three types: the electron-neutrino, the muon-neutrino and the tau-neutrino. Electron-neutrinos, which are associated with the familiar electron, are emitted in vast numbers by the nuclear reactions that fuel the Sun. Since the early 1970s, several experiments have detected neutrinos arriving on Earth, but they have found only a fraction of the number expected from detailed theories of energy production in the Sun. This meant there was something wrong with either the theories of the Sun, or the understanding of neutrinos.
"We now have high confidence that the discrepancy is not caused by problems with the models of the Sun but by changes in the neutrinos themselves as they travel from the core of the Sun to the earth," says Dr. Art McDonald, SNO Project Director and Professor of Physics at Queen's University in Kingston, Ontario. "Earlier measurements had been unable to provide definitive results showing that this transformation from solar electron neutrinos to other types occurs. The new results from SNO, combined with previous work, now reveal this transformation clearly, and show that the total number of electron neutrinos produced in the Sun are just as predicted by detailed solar models."
The SNO scientists present their first results today in a paper submitted to Physical Review Letters and in presentations at the Canadian Association of Physicists Annual Conference at Victoria, B.C. and at SNO Institutions in the U.S. and the U.K. "It is incredibly exciting, after all the years spent by so many people building SNO, to see such intriguing results coming out of our first data analysis - with so much more to come." says UK Co-spokesman Prof. David Wark of the Rutherford/Appleton Laboratory and the University of Sussex.
The determination that the electron neutrinos from the Sun transform into neutrinos of another type is very important for a full understanding of the Universe at the most microscopic level. This transformation of neutrino types is not allowed in the Standard Model of elementary particles. Theoreticians will be seeking the best way to incorporate this new information about neutrinos into more comprehensive theories.
The direct evidence for solar neutrino transformation also indicates that neutrinos have mass. By combining this with information from previous measurements, it is possible to set an upper limit on the sum of the known neutrino masses. "Even though there is an enormous number of neutrinos in the Universe, the mass limits show that neutrinos make up only a small fraction of the total mass and energy content of the Universe." says Dr. Hamish Robertson, U.S. Co-Spokesman and Professor of Physics at the University of Washington in Seattle.
The SNO detector, which is located 2000 meters below ground in INCO's Creighton nickel mine near Sudbury, Ontario, uses 1000 tonnes of heavy water to intercept about 10 neutrinos per day. The results being reported today are the first in a series of sensitive measurements that SNO is performing. From this initial phase, the SNO scientists report on an accurate and specific measurement of the number of solar electron neutrinos reaching their detector, by studying a reaction unique to heavy water where a neutron is changed into a proton. They combined these first SNO results with measurements by the SuperKamiokande detector in Japan of the scattering of solar neutrinos from electrons in ordinary water (offering a small sensitivity to other neutrino types), to provide the direct evidence that neutrinos oscillate.
At the beginning of June the SNO scientists began the next phase of their measurements, by adding salt to the heavy water, to study another neutrino reaction with deuterium that provides a large sensitivity to all neutrino types. Their further measurements can address the transformation of neutrino type with even greater sensitivity, as well as studying other properties of neutrinos, of the Sun and supernovae.
Background Information on the Sudbury Neutrino Observatory
The Sudbury Neutrino Observatory is a unique neutrino telescope, the size of a ten-storey building, 2 kilometers underground in INCO's Creighton Mine near Sudbury Ontario planned, constructed and operated by a 100-member team of scientists from Canada, the United States and the United Kingdom. Through its use of heavy water, the SNO detector provides new ways to detect neutrinos from the sun and other astrophysical objects and measure their properties. For many years, the number of solar neutrinos measured by other underground detectors has been found to be smaller than expected from theories of energy generation in the sun. This has led scientists to infer that either the understanding of the Sun is incomplete, or that the neutrinos are changing from one type to another in transit from the core of the Sun.
The SNO detector has the capability to determine whether solar neutrinos are changing their type en-route to Earth, thus providing answers to questions about neutrino properties and solar energy generation.
The SNO detector consists of 1000 tonnes of ultra-pure heavy water enclosed in a 12-meter diameter acrylic plastic vessel, which in turn is surrounded by ultra-pure ordinary water in a giant 22-meter diameter by 34-meter high cavity. Outside the acrylic vessel is a 17-meter diameter geodesic sphere containing 9456 light sensors or photomultiplier tubes, which detect tiny flashes of light emitted as neutrinos are stopped or scattered in the heavy water. The flashes are recorded and analyzed to extract information about the neutrinos causing them. At a detection rate on the order of 10 per day, many days of operation are required to provide sufficient data for a complete analysis. The laboratory includes electronics and computer facilities, a control room, and water purification systems for both heavy and regular water.
The construction of the SNO Laboratory began in 1990 and was completed in 1998 at a cost of $73M CDN with support from the Natural Sciences and Engineering Research Council of Canada, the National Research Council of Canada, the Northern Ontario Heritage Foundation, Industry, Science and Technology Canada, INCO Limited, the United States Department of Energy, and the Particle Physics and Astronomy Research Council of the UK. The heavy water is on loan from Canada's federal agency AECL with the cooperation of Ontario Power Generation, and the unique underground location is provided through the cooperation and support of INCO Limited.
Measurements at the SNO Laboratory began in 1999, and the detector has been in almost continuous operation since November 1999 when, after a period of calibration and testing, its operating parameters were set in their final configuration.
Further information about the SNO detector can be found on the SNO Detector page.
Send page by E-Mail Many attitudes 'in our genes'
Posted: Monday, June 18, 2001
(BBC) Everything from liking rollercoasters to attitudes to the death penalty is influenced by our genes, say researchers.
A study carried out on twins has found differences in certain attitudes are partly due to genetic influences.
Although attitudes are learnt, scientists in Canada believe individual differences may arise, at least in part, because of our genetic makeup.
Scientists in Canada surveyed 360 pairs of twins and looked at their attitudes to a wide range of issues - from reading to the death penalty for murder.
Out of the 30 attitudes studied, 26 of them appeared to be under some genetic influence.
The death penalty, abortion, playing organised sport and rollercoaster rides were the ones that appeared to be most influenced by genes.
The four found not to be subject to a genetic effect were attitudes towards separate roles for men and women, playing bingo, easy access to birth control, and being assertive.
There appeared to be trends in the study's findings. For instance, genetically inherited attitudes were most likely to be associated with the preservation of life, equality and exercise, while those with the least influence were intellectual activities like playing chess and reading.
There is doubt, though, that genes are directly involved in how we perceive things.
The authors, based at the University of Western Ontario and the University of British Columbia, believe it is much more likely that a complex relationship between genes, personality and physical appearance is involved in shaping our attitudes.
"Presumably, these characteristics predisposed individuals to form particular kinds of attitudes, thereby contributing to the genetic determination of individual differences in those attitudes," said Dr James Olson and colleagues.
He said: "For example, a person with inherited physical abilities such as good coordination and strength might be more successful at sports than less athletically inclined individuals, resulting in the more athletic person developing favourable attitudes to sport." More
Send page by E-Mail Ghostly particle mystery 'solved'
Posted: Monday, June 18, 2001
(BBC) An international team of physicists claims to have solved a 30-year-old mystery: the puzzle of the missing solar neutrinos.
In the past scientists detected only about a third of the expected quantity of these tiny particles coming from the powerhouse at the Sun's core. It was a major flaw in our understanding of matter and energy.
New observations made by a giant underground neutrino detector in Canada show that the solution lies not with the Sun, but with the neutrinos, which change as they travel from the core of the Sun to the Earth.
The finding raises new questions about the so-called Standard Model of Particle Physics, which seeks to explain the basic building blocks of matter.
The research was carried out at the Sudbury Neutrino Observatory (SNO), Ontario, in collaboration with Oxford University, UK.
"We now have high confidence that the discrepancy is not caused by problems with the models of the Sun but by changes in the neutrinos themselves as they travel from the core of the Sun to the Earth," says Dr Art McDonald, SNO project director and professor of physics at Queen's University in Kingston, Ontario, Canada.
"It's taken longer than we thought, but it's all been well worthwhile," says Dr Steve Biller, of Oxford University. "We've pushed the limits of engineering, chemistry... and patience, in order to push the limits of physics."
Neutrinos are fundamental particles of matter. They are often called 'ghostly' because they interact so weakly with other forms of matter.
They come in three types: the electron-neutrino, the muon-neutrino and the tau-neutrino. Electron-neutrinos are emitted in vast numbers by the nuclear reactions that power the Sun. More
Send page by E-Mail Oceanic Bacterial Photopigments Converts Light
Posted: Thursday, June 14, 2001
(Science Daily) Research Institute (MBARI). Their discovery is reported in this week’s issue of the journal Nature. Last fall in the journal Science, the MBARI researchers described the first marine bacterium with this photopigment that can generate cellular energy using light.
"Advances in technology are letting us view the marine microbial world in new ways," said Ed DeLong, leader of the MBARI research group. Colleague Oded Béjà added, "We were lucky to find these different proteorhodopsins out there in the vast ocean.”
The scientists observed chemical activity stimulated by light flashes in native marine microbes, similar to the activity seen in earlier laboratory studies of proteorhodopsin and bacteriorhodopsin. These observations showed that the microbes and active photopigment were present in abundance at the ocean’s surface.
The researchers also showed that genetic variants of the photoactive microbes contain different proteorhodopsins in different ocean habitats. The protein pigments appear to be tuned to absorb light of different wavelengths that match the quality of light available in different environments. Specific adaptations in the photopigment structure have optimized different variants functioning best at different depths in the water column. More
Send page by E-Mail Neutron stars: The star with a soft centre
Posted: Wednesday, June 13, 2001
(New Scientist) TO TRY to understand neutron stars, researchers have abandoned telescopes for a new tool a billion billion times smaller--the nucleus of a lead atom.
Neutron stars, like the one at the heart of the Crab Nebula (above), have a radius of only a dozen kilometres or so but weigh more than the Sun. Despite often pumping out X-rays or radio signals, it is hard to determine the structure of a neutron star just from its radiation.
Researchers think that a neutron star is solid on the outside with a liquid centre. They want to know how thick the solid neutron crust is, as this affects many of the star's properties--from how fast it cools to how well it emits gravitational waves.
Charles Horowitz of Indiana University in Bloomington and Jorge Piekarewicz of Florida State University in Tallahassee believe that they can get an idea of the crust's thickness by measuring the skin of neutrons that covers the nucleus of a lead atom. "We're trying to use lead-208 as a miniature surrogate," Horowitz says.
A lead nucleus is a staggering 55 orders of magnitude less massive than a neutron star, but because both are nuclear matter they are governed by the same physics, which is enshrined in an "equation of state". Physicists do not know the exact form of the equation of state for either a neutron star or lead nucleus. But as Horowitz and Piekarewicz gradually modified the equations, they found a close correlation between the values they got for the star's crust and the nucleus's skin.
"There is definitely a relationship there," says astrophysicist Jim Lattimer of the State University of New York at Stony Brook. "If we can tighten that relationship, it should be a useful tool."
That tool may be put to use in a couple years at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia. Physicists are planning to measure the neutron skin of lead-208 nuclei by bouncing electrons off it. Once they know the skin thickness, neutron stars will be a cinch.
Physical Review Letters More
Send page by E-Mail Quasars Found: Most Distant Objects Ever Seen
Posted: Wednesday, June 6, 2001
(ABC Science) The announcement today at a meeting of the American Astronomical Society marks the fourth time the Sloan Digital Sky Survey has pushed closer to the birth of the universe some 13 billion years ago.
"Our vision has consistently pressed deeper and deeper in time, and now we’re within 800 million years," said Donald Schneider of Pennsylvania State University.
Earlier discoveries were about a billion years away from the birth of the universe.
Quasars are galaxies with very active and bright center objects, thought to be powered by black holes. They can shine with the brilliance of a trillion suns.
The Sloan project, a five-year, $80 million undertaking, seeks to digitally survey the sky, map the universe and define its structure in three dimensions. It uses telescopes atop Apache Point, N.M.
Astronomers also heralded the first release of data from the survey today. The data consists of precision measurements of 14 million objects scattered throughout the universe. Included are more than 13,000 quasars, including 26 of the 30 most distant known.
Astronomers expect to release the full set of data over the next five years. It will be the biggest flood of information in the history of astronomy. More
Send page by E-Mail Astronomers Report Galactic Baby Boom
Posted: Tuesday, June 5, 2001
Johns Hopkins University (http://www.jhu.edu/)
A pair of young astronomers has found a bumper crop of "infant" galaxies that may help scientists develop new insights into the beginnings of galaxy formation.
Reporting at this week's meeting of the American Astronomical Society in Pasadena, Calif., postdoctoral fellows Sangeeta Malhotra and James Rhoads will present what is by far the largest finding to date of very distant and highly energetic young galaxies. They found 150 in a full-moon-sized patch of sky.
"It's great to have found such a large number of these galaxies, because it's going to be harder to shove them under the rug," says Malhotra, a Hubble fellow in The Krieger School of Arts and Sciences at the Johns Hopkins University. "We're going to have to think harder about what's happening in galaxy formation and star formation at these times, early in the history of the universe."
Among the key questions, according to Malhotra, will be what makes the young galaxies so bright: intense bursts of star formation, the activity of a massive black hole at the center of the galaxy or something else?
"In about half of these galaxies, our models of how stars behave can't explain the strength of a characteristic spectral line we use to identify the galaxies," she says.
For their survey, Malhotra and Rhoads used a new instrument known as the Mosaic CCD camera on the 4-meter Mayall Telescope at Kitt Peak National Observatory, which is located near Tucson, Ariz. The camera, one of the first such instruments on a large telescope, enabled them to image distant, faint sources of radiation over a relatively wide patch of sky. They took their data from an area in the constellation Bootes, in the direction of the star Arcturus.
This field was chosen because there is already an extensive complementary survey there, led by Buell Jannuzi and Arjun Dey of the National Optical Astronomy Observatory. "This is a location with nothing much in the nearby universe, so we have a clean line of sight to the very distant universe," says Rhoads, who is an institute fellow at the Hubble Space Telescope Science Institute in Baltimore.
Malhotra and Rhoads used specially designed filters to help screen the 40,000 objects their survey detected for likely candidates for young galaxies.
"We were looking for a spectral signature known as a Lyman-alpha line that is created by ionized hydrogen," Malhotra says. "It suggests very energetic activity, and it's a signal we don't see in present-day galaxies."
When they applied a filter designed to pick up that characteristic component of the light, and compared the resulting images, objects that appeared brighter in the filtered image were moved up on the list of candidates for distant, young galaxies.
"With the aid of follow-up spectroscopic observations at the Keck telescope in Hawaii, our collaborators Arjun Dey, Daniel Stern, and Hy Spinrad confirmed that these galaxies are about 10 billion light years away, at a redshift of 4.5," says Malhotra. "Light we see now from those galaxies left them when the universe was barely one-tenth of its present age."
Rhoads and Malhotra are planning additional surveys in the near future. "We are designing filters to go to even younger times," says Rhoads.
"We hope we're at the beginning of building up a complete picture of what's going on in the universe at this early age," says Malhotra. "As we collect more and more of these galaxies, we'll get a better sense of what's usual and what's unusual. Follow-up observations in X-rays and infrared radiation will further help us understand the nature of these objects."
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