|Dangerous Cells! |
Meet The Chlamydiae! Top Nuts!
Buncefield Fire, Himalaya Quakes!
Mapping Dark Matter!
|Dangerous Cells! |
On the surface, she said, it appears that drivers are
trying to accomplish just two tasks driving and
conversing. But each task is complicated and multi-
faceted, greatly increasing the "cost" of switching.
(US Census Bureau)
Oregon State University News Release
December 9, 2005 - Most people can rather efficiently walk and chew gum at the same time, but when it comes to more complicated "multi-tasking" like driving and talking on a cell phone there is a price to pay.
And no one, it seems, is immune.
"There is a cost for switching from one task to another and that cost can be in response time or in accuracy," said
Mei-Ching Lien, an assistant professor of psychology at Oregon State University. "Even with a seemingly simple task, structural cognitive limitations can prevent you from efficiently switching to a new task."
Psychologists who study multi-tasking have argued for years about whether these "information bottlenecks" occur because people are inherently lazy, or because they have a fundamental inability to switch from one task to another. New studies by Lien and her colleagues at the NASA Ames Research Center in California suggest it is the latter.
Results of their study have been published in the Journal of Experimental Psychology.
In their study the researchers asked volunteers to respond to a variety of auditory and visual cues then measured the responses. When the volunteers prepared for one task, such as responding to the color red, their responses were swift and accurate. When the researchers added a second element the recognition of shapes as well as color the task switch considerably delayed the responses, even when the volunteers were prepared for it.
"People are surprised that there is such a delay," Lien said. "Practice can help a person reduce the 'cost' of switching tasks, but it apparently cannot eliminate that cost."
Lien said the study can be applied to the real world, especially to drivers who talk on cell phones. On the surface, she said, it appears that drivers are trying to accomplish just two tasks driving and conversing. But each task is complicated and multi-faceted, greatly increasing the "cost" of switching. The result: inattention and slow reaction times.
"A lot of people think talking on the cell phone while driving is natural, but each time someone asks a question or changes the subject, it's like taking on a new task," Lien said. "It requires a certain amount of thought and preparation. It's actually quite different than listening to the radio, where you don't need to respond.
"And it's also different from talking to a passenger in the vehicle," she added. "In most cases, a passenger can observe when there is a dangerous traffic situation and keep quiet. But someone calling you on a cell phone won't have a clue."
There are individual differences in the costs of multi-tasking, Lien said. In her lab studies, a typical response to a single stimulus might take 300 milliseconds. Adding a second task increases the response to about 800 milliseconds. A millisecond is 1/1000th of a second, so the delay may not seem like much until you extend the difference to a car driving 60 miles an hour and realize the response rate more than doubles, Lien said.
In her lab studies, she has yet to test any volunteers who are immune to delays in multi-tasking, though she says some students do much better than others.
"I have to say that the best ones are those who play a lot of video games," she pointed out. "Those are lab studies, however, and not driving tests."
She became interested in multi-tasking while working at the NASA Ames Research Center in Moffett, Calif., where she was part of a team analyzing cockpit design and pilot function. One of the projects focused on how much information can safely and efficiently be included on screens and monitors so the pilots' delay and loss of accuracy are minimized.
"We learned to modify some of the screens to mitigate their weaknesses," she said.
While Lien's studies suggest that simplifying tasks leads to greater efficiency, technology is complicating everything we do including driving. Drivers often use cell phones, CD players, global positioning systems, radar detectors, complicated dashboards and other devices. At the same time, they must navigate increasing traffic, read a plethora of signs, and handle other distractions.
"We may be undermining our ability to drive safely," Lien said.
Oregon State University - http://www.orst.edu
Cell Phones Increase Distress Level
Blackwell Publishing Ltd. News Release
Andrew Wielawski's sculpture
"Nude With Cell Phone" (1997)
December 12, 2005 - The ongoing use of this communications technology, as compared to computer-based use such as email, is linked to increased psychological distress and reduced family satisfaction.
For both men and women, cell phones allow job worries to spill over into home life. But only women also experience the opposite effect--the spillover of home concerns into their work life. For women, both work and family worries and responsibilities affected their levels of distress and family satisfaction.
The findings suggest that, although technology may make everyone more accessible, it does so with negative consequences.
The authors interviewed working couples over two time periods, 1998-1999 and 2000-2001. Use of cell phones and pagers in that two-year time period decreased family satisfaction and increased distress, and negative work-to-family (for men and women) and family-to-work (for women) spillover.
The author measured the participants' psychological distress; she asked them to state how often in the past month they felt feelings ranging from "in good spirits" to "everything was an effort."
Participants were also asked questions such as whether they could turn to their family for help and if they were satisfied with the support they receive.
"The question of 'blurred boundaries' may become an irrelevant one for the next generation of workers, spouses, and parents because they cannot imagine life any other way," the author states.
"Even so, worries about the implications for technology users are not likely to disappear."
This study is published in the December issue of the Journal of Marriage and Family.
Blackwell Publishing Ltd. - http://www.blackwellpublishing.com
|Meet The Chlamydiae! |
Chlamydiae are intracellular parasites that get vitamins,
amino acids, ATP, and other vital cellular molecules from
their host cell. Chlamydia trachomatis, a species within
this phylum, causes a venereal disease in humans that is
commonly referred to as "chlamydia" or "trachoma," and
Chlamydophila pneumoniae causes a type of pneumonia
that that creates chest infections. (Sidwell Friends School)
American Society for Cell Biology News Release
December 11, 2005 - Invasive bacterial pathogens, the Chlamydiae know us very, very well. The Chlamydiae learned to parasitize eukaryotic cells half a billion years ago by reprogramming cellular functions from within.
In humans today, chlamydial infections are responsible for a range of ailments from sexually transmitted infections to atypical pneumonias to chronic severe disorders such as pelvic inflammatory disease and atherosclerosis. The Centers for Disease Control says that Chlamydia trachomatis is the most common sexually-transmitted infection in the US, with three million new cases a year.
Chlamydia gets around because it knows its hosts so well. It's an "obligate intracellular parasite" which means that it relies on its eukaryotic host for everything from reproduction to synthesizing ATP, all while living inside a membrane-bounded vacuole that provides a protected, fertile environment for the bacteria to grow and multiply.
Because lipid acquisition from the host is necessary for chlamydial replication, these pathogens are essentially lipid parasites. So, to add insult to injury, Chlamydia apparently lives on our fat.
Lipid droplets are fat-rich structures found in all eukaryotic cells. In humans, lipid droplets are abundant in adipocytes, our professional fat storage cells, where they have traditionally been regarded as passive storage depots of excess fat. However, recent studies have reassessed their role. Lipid droplets are now known to be motile, dynamic and enriched for proteins known to regulate lipid synthesis, membrane traffic and cell signaling.
Now in new research presented Sunday at the 45th Annual Meeting of the American Society for Cell Biology in San Francisco, Yadunanda Kumar and Raphael Valdivia of Duke University Medical Center report that Chlamydia loves our lipid droplets.
Scanning electron micrograph of a chlamydia
inclusion body leaving a host cell in a dramatic
fashion. The inset shows a closeup of the
elementary bodies breaking free of the inclusion
body. (UBC Centre for Disease Control)
The discovery of an interaction between lipid droplets and Chlamydia was made as Kumar and Valdivia performed the genetic equivalent of an end-run. Chlamydia is not amenable to direct genetic manipulation so the researchers moved the pathogen's genes elsewhere, inserting them into the eukaryotic cells of baker's yeast. The resulting chlamydial proteins were screened for those that targeted to yeast intracellular organelles. They identified four proteins that were specifically recruited to lipid droplets.
The researchers found that Chlamydia not only directs lipid droplets to its protective vacuole but also causes the proliferation of new lipid droplets on the host. The co-option of lipid droplets appears to be essential for Chlamydia pathogenesis. When the researchers used drugs to inhibit lipid droplet formation in the host, they sharply impaired bacterial growth.
That finding immediately presents a new target for anti-Chlamydia drugs but it also suggests an entirely novel pathogenic mechanism. "We propose that Chlamydia use lipid droplets in a previously unknown pathway for lipid acquisition," says Kumar. "Alternatively, it is possible that the recruitment of lipid droplets constitutes an example of 'organelle mimicry' where Chlamydia escapes recognition by the host by cloaking itself in these fat-rich structures."
Understanding host lipid transport by Chlamydiae may have further implication for chronic infections, the researchers say. For example, lipid-rich macrophages ("foam cells") are a symptom in chlamydial pneumonia. Because foam cells are a key element in development of atherosclerosis, lipid droplet co-option also suggests a possible explanation for the association between chlamydial infections and heart disease.
American Society for Cell Biology - http://www.ascb.org
|Top Nuts for Good Health |
American Chemical Society News Release
December 7, 2005 - Researchers have known for some time that nuts and seeds are rich sources of phytosterols, a class of plant chemicals that have been shown to reduce cholesterol levels and improve heart health.
In what is believed to be the most comprehensive analysis to date of the phytosterol content of nuts and seeds, chemists at Virginia Polytechnic Institute and State University in Blacksburg, Va., analyzed some 27 nut and seed products and found that pistachios and sunflower kernels had the highest levels of phytosterols among the nuts and seeds that are most commonly consumed as snack foods in the United States.
Their study appears in the Nov. 30 issue of the American Chemical Society's Journal of Agricultural and Food Chemistry.
Sesame seed and wheat germ actually ranked highest but are not consumed as frequently as individual foods, the researchers say. Brazil nuts and walnuts ranked the lowest in phytosterols, they say. The chemists caution that phytosterols are not the only food component involved in lowering cholesterol and that other compounds may also play a role. A well-balanced diet and frequent exercise are important keys to good health, they stress.
The American Chemical Society is a nonprofit organization, chartered by the U.S. Congress, with a multidisciplinary membership of more than 158,000 chemists and chemical engineers. It publishes numerous scientific journals and databases, convenes major research conferences and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.
American Chemical Society - http://www.acs.org
|Buncefield Oil Depot Fire Blackens London |
London covered by oil fire (ESA)
European Space Agency News Release
December 12, 2005 - London is completely blanketed by the black plume of smoke from Europe's worst peacetime fire in this Envisat image, taken within five hours of the blaze beginning.
This image was acquired at 10:45 GMT on Sunday morning by the Medium Resolution Imaging Spectrometer (MERIS), one of ten instruments aboard Envisat, Europe's largest satellite for environmental monitoring. This Reduced Resolution mode image has a spatial resolution of 1200 metres, and shows the cloud spread across a span of around 140 km.
The pall of smoke comes from a fire at Buncefield oil depot on the outskirts of Hemel Hempstead. Buncefield is the fifth largest fuel storage depot in the UK, distributing millions of tonnes of petrol and other oil products per year, including aviation fuel to nearby Luton and Heathrow Airports.
Buncefield is located at the topmost part of the cloud, with light winds blowing the smoke south-west and south-east to cover a large part of Southern England. On Monday morning firefighters began laying down 250 000 litres of foam to control the blaze, which is reported to be the largest industrial fire in Europe since 1945.
The fire began with a series of explosions taking place on Sunday morning at around 06:00 GMT. Nobody was killed in the explosion but 43 people have been injured, and more than 2000 people have been evacuated from the vicinity of the depot.
All but seven out of 26 storage tanks at the depot are currently burning each tank contains more than 13 million litres of fuel. Health experts have warned susceptible people to avoid breathing in the acrid black smoke. The heat of the fire has driven smoke particles high into the sky, with aircraft reporting pollution reaching above 2750 metres, and the cloud stretching from East Anglia to Salisbury Plain.
European Space Agency - http://www.esa.int
|Himalaya Quakes! |
Himalaya Mountains from space (NASA)
University of Colorado at Boulder News Release
December 7, 2005 - While the rupture zones of recent major earthquakes are immune to similar-sized earthquakes for hundreds of years, they could be vulnerable to even bigger destructive temblors sooner than scientists suspect, according to analysis by University of Colorado seismologist Roger Bilham.
Bilham and his research colleagues explained that the magnitude 9.3 Indian Ocean earthquake of December 2004 showed scientists that a giant earthquake can rupture through a region with a recent history of quakes with magnitudes as large as 7.9 on the Richter Scale.
"Following what we learned in 2004, we believe that regions of the Himalaya that have recently experienced magnitude 7.8 earthquakes - like the Kangra district, a hundred years ago - may not be immune to a future larger earthquake," he said.
Bilham's research of Himalayan earthquakes in the last 1,000 years is part of findings presented in an invited talk, "Unprecedented massive earthquakes in the Himalaya driven by elastic strain stored within the Tibetan Plateau?" Dec. 7 at the American Geophysical Union's fall meeting in San Francisco.
Bilham recently returned from Kashmir, where he conducted a series of measurements along with Pakistani scientists to assess subsurface fault slip and damage in that region's October earthquake.
"The Kashmir event released almost 100 times less energy than the Sumatra-Andaman quake in 2004," he said. "The Kashmir rupture was about 16 times smaller in length and five times smaller in width, yet it flattened whole cities in its path."
The Kashmir earthquake was the deadliest earthquake ever in the Indian subcontinent, mostly because of the poor construction quality in the area, Bilham said. "Most of the buildings that collapsed had been constructed in the past two decades.
"It is distressing to see how little attention has been focused on this earthquake by news media in the United States," he said.
Bilham believes medieval earthquakes beneath the Himalaya may have been larger than any in the past 300 years. Bilham and his colleagues are trying to determine what governs the recurrence interval and the size of these historically much larger earthquakes.
Geographical repartition of the last big Himalayan
earthquakes : Western and Center Nepal had been
spared since at least two centuries. (National
Seismological Centre, Nepal)
"We postulate that a giant reservoir of elastic energy exists not just in the Himalaya but also beneath southern Tibet," he said. "This reservoir of energy is tapped by Himalayan earthquakes more efficiently if ruptures are geographically long."
Bilham and his colleagues developed a "theoretical law" linking earthquakes of different size to their geographic length and repeat time. They concluded that recent earthquakes require about 500 years to repeat, but the medieval ones require almost 2,000 years.
"We suggest that these rare events must have exploited much longer ruptures than any we have seen recently, like those that slipped in the Kangra and Kashmir earthquakes," he said. "We find also that these rare great events can re-rupture parts of the plate boundary that slip in modest earthquakes up to magnitude 7.6. As a result, recent rupture zones could be vulnerable to greater destruction sooner than one might suspect from India's rate of approach toward Asia."
The tremendous Indian Ocean earthquake in 2004 gave seismologists an unprecedented look at the mechanics of the world's largest earthquakes. Using data recorded by digital seismometers all over the world, scientists were able to determine that the rupture propagated 1,000 miles from south to north at 5,000 miles per hour during the first 10 minutes of the earthquake.
University of Colorado at Boulder - http://www.colorado.edu
|Plasma Escapes Newborn Star |
Using highly-resolved images from the Hubble Space
Telescope, a international team of astronomers at Rice
University and four other institutions created the first
moving pictures of a stellar jet. These massive streams
of plasma spew from the poles of newborn stars, playing
a critical, yet poorly understood role in star formation.
(Patrick Hartigan/ Rice University)
Rice University News Release
December 5, 2005 - Like traffic on a freeway, plasma spewing from the poles of newborn stars moves in clumps that travel at different speeds. When fast-moving particles run into slower material on these cosmic freeways, the resulting "traffic jams" create massive shock waves that travel trillions of miles.
Thanks to highly resolved images from the Hubble Space Telescope, a team of astronomers have created the first moving pictures of one of these cosmic freeways, which are known as stellar jets. The movies allow scientists to trace these stellar jet shock waves for the first time, gleaning important clues about a critical, yet poorly understood process of starbirth. The results appeared in the November issue of Astronomical Journal.
"When it comes to actually showing exactly what's going on, there's just nothing like a movie," said study co-author Patrick Hartigan, associate professor of physics and astronomy at Rice University. "You can look at a still image and make up all kinds of stories, but they all go out the window when you see a movie."
Hartigan and researchers from the Cerro Tololo Inter-American Observatory (CTIAO) in Chile, Arizona State University (ASU), the University of Hawaii and the University of Colorado at Boulder, made the movies using images taken in 1994 and 1999 of a newly formed star called HH 47 in the constellation Vela.
Because Hubble flies above the Earth's atmosphere, it can take much clearer images than Earth-based telescopes. As a result, Hartigan and his co-researchers were able to resolve objects in the Hubble images that were 20 times smaller than objects resolved in similar images taken on Earth. This extra resolution, and the five-year gap between Hubble surveys of HH 47, allowed them to make moving pictures of the stellar jet shock waves moving away from the new star.
(Patrick Hartigan/ Rice University)
"Imagine taking a photo at a football game that shows the quarterback throwing the ball at the start of a play," Hartigan said. "There is no way to know what happened in the play without a second photograph at the end of the play that shows a touchdown, incomplete pass, interception, or whatever occurs. If you take a series of photos, with enough resolution to make out the ball, you could determine whether someone ran with the ball or caught a pass, and you could determine the relative position of all of the players to one another at any time during the play.
"Like the time-lapse images of the game, our movies give us the ability to track the movement of individual features within the stellar jet, both relative to stationary objects and relative to other objects that are moving within the jet at a different speed," Hartigan said.
New stars form out of giant clouds of gas and dust. Within these clouds, strong gravitational forces pull material together into a tight ball surrounded by a large spinning disk. The new star forms out of the ball, and any planets that might form do so in the disk.
Through processes not well-understood, much of the disk material gradually spirals into the star, and the resulting energy from this process drives stellar jets of plasma that erupt from the star at perpendicular angles to the spinning accretion disk. The material thrown away from the star in the jets acts as a brake on disk, slowing its rotation and allowing more material to fall into the growing star. Scientists know stellar jets play an integral role in star formation, but they have yet to determine the specifics of their role, or how it is carried out.
The research was funded by NASA. Co-authors on the study include CTIO's Steve Heathcote, ASU's Jon A. Morse, University of Hawaii's Bo Reipurth and University of Colorado at Boulder's John Bally.
Rice University - http://www.rice.edu
|Mapping Dark Matter |
On the left hand side is an ACS image that shows the lensed
galaxy elongated vertically by gravity. However, when the
same galaxy is observed with the Very Large Telescope (VLT)
at Cerro Paranal, we only see a small blob indicating no hints
of lensing (right panel). The shape information has been
destroyed by the atmospheric turbulence even if it is much
weaker there than at the sea level. (JHU)
Johns Hopkins University News Release
December 9, 2005 - Clues revealed by the recently sharpened view of the Hubble Space Telescope have allowed astronomers to map the location of invisible "dark matter" in unprecedented detail in two very young galaxy clusters.
A Johns Hopkins University-Space Telescope Science Institute team reports its findings in the December issue of Astrophysical Journal.
Other, less-detailed observations appeared in the January 2005 issue of that publication.
The team's results lend credence to the theory that the galaxies we can see form at the densest regions of "cosmic webs" of invisible dark matter, just as froth gathers on top of ocean waves, said study co-author Myungkook James Jee, assistant research scientist in the Henry A. Rowland Department of Physics and Astronomy in Johns Hopkins' Krieger School of Arts and Sciences.
"Advances in computer technology now allow us to simulate the entire universe and to follow the coalescence of matter into stars, galaxies, clusters of galaxies and enormously long filaments of matter from the first hundred thousand years to the present," Jee said. "However, it is very challenging to verify the simulation results observationally, because dark matter does not emit light."
Jee said the team measured the subtle gravitational "lensing" apparent in Hubble images -- that is, the small distortions of galaxies' shapes caused by gravity from unseen dark matter -- to produce its detailed dark matter maps. They conducted their observations in two clusters of galaxies that were forming when the universe was about half its present age.
"The images we took show clearly that the cluster galaxies are located at the densest regions of the dark matter haloes, which are rendered in purple in our images," Jee said.
This is the snapshot of the computer simulation
of the dark matter Universe. These filamentary
structures are called "cosmic webs" of dark matter.
The work buttresses the theory that dark matter - which constitutes 90 percent of matter in the universe -- and visible matter should coalesce at the same places because gravity pulls them together, Jee said. Concentrations of dark matter should attract visible matter, and as a result, assist in the formation of luminous stars, galaxies and galaxy clusters.
Dark matter presents one of the most puzzling problems in modern cosmology. Invisible, yet undoubtedly there -- scientists can measure its effects -- its exact characteristics remain elusive. Previous attempts to map dark matter in detail with ground-based telescopes were handicapped by turbulence in the Earth's atmosphere, which blurred the resulting images.
"Observing through the atmosphere is like trying to see the details of a picture at the bottom of a swimming pool full of waves," said Holland Ford, one of the paper's co-authors and a professor of physics and astronomy at Johns Hopkins.
The Johns Hopkins-STScI team was able to overcome the atmospheric obstacle through the use of the space-based Hubble telescope. The installation of the Advanced Camera for Surveys in the Hubble three years ago was an additional boon, increasing the discovery efficiency of the previous HST by a factor of 10.
The team concentrated on two galaxy clusters (each containing more than 400 galaxies) in the southern sky.
"These images were actually intended mainly to study the galaxies in the clusters, and not the lensing of the background galaxies," said co-author Richard White, a STScI astronomer who also is head of the Hubble data archive for STScI. "But the sharpness and sensitivity of the images made them ideal for this project. That's the real beauty of Hubble images: They will be used for years for new scientific investigations."
The result of the team's analysis is a series of vividly detailed, computer-simulated images illustrating the dark matter's location. According to Jee, these images provide researchers with an unprecedented opportunity to infer dark matter's properties.
Computer simulation of the universe (NASA)
The clumped structure of dark matter around the cluster galaxies is consistent with the current belief that dark matter particles are "collision-less," Jee said. Unlike normal matter particles, physicists believe, they do not collide and scatter like billiard balls but rather simply pass through each other.
"Collision-less particles do not bombard one another, the way two hydrogen atoms do. If dark matter particles were collisional, we would observe a much smoother distribution of dark matter, without any small-scale clumpy structures," Jee said.
Ford said this study demonstrates that the ACS is uniquely advantageous for gravitational lensing studies and will, over time, substantially enhance understanding of the formation and evolution of the cosmic structure, as well as of dark matter.
"I am enormously gratified that the seven years of hard work by so many talented scientists and engineers to make the Advanced Camera for Surveys is providing all of humanity with deeper images and understandings of the origins of our marvelous universe," said Ford, who is principal investigator for ACS and a leader of the science team.
The ACS science and engineering team is concentrated at the Johns Hopkins University and the Space Telescope Science Institute on the university's Homewood campus in Baltimore. It also includes scientists from other major universities in the United States and Europe. ACS was developed by the team under NASA contract NAS5-32865 and this research was supported by NASA grant NAG5-7697.
For graphics that illustrate this research, click on the following link: http://www.jhu.edu/news/home05/dec05/darkpix.html