Studying How Germs Spread

Mark Nicas has given some of his best years to spittle. He builds models – the mathematical kind – of how someone else's slobber ends up on you. The size of the particles, whether they come out in a dry cough or a wet sneeze, their evaporation rate, air speed – these are all complications, reasons why people like Nicas can spend careers piling up academic papers, all the while building up a healthy respect for pathogens.

Nicas, whose day job is at the University of California-Berkeley is one of a team of scientists affiliated with the Center for Advancing Microbial Risk Assessment (CAMRA), funded jointly by the U.S. Department of Homeland Security Science and Technology Directorate (DHS S&T) and the U.S. Environmental Protection Agency (EPA).
"In terms of homeland security, knowing how germs are spread is an important factor in countermeasures for potential biological attacks or pandemics," says Dr. Matthew Clark, Director of DHS S&T's Office of University Programs, who helps fund Nicas' research.
As an interdisciplinary research hub, CAMRA's goal is to help DHS S&T understand the risks associated with certain biological agents, and build a national network beyond the scientific community for sharing those insights.
Statistical predictions about flying saliva may seem like academic caricature. But they have important real-world applications to terrorist biological attacks and deadly diseases like bird flu that can ripple quickly through American cities. Disaster comes from the mouth, warns an ancient Chinese proverb on the dangers of linguistic drivel. But understanding the infectious potential of biological drivel may be the secret to restoring national health in a pandemic.
"When you get on an airplane, it's always best to sit at least three rows from a coughing person," said Nicas. "You don't know what they have."
Nicas used a Department of Homeland Security grant to test his airborne dispersion model for large and small particles in a small laboratory.
He isn't kidding about the airplane advice. It's a version of the three-foot rule—common in infection control circles—which says that transmitting pathogens between people through inhalation typically occurs inside of three feet. Outside that range, large particles carrying most of the pathogens fall out of the air quickly. On airplanes, the risk of infection declines rapidly between rows because of cabin design that circulates air within, not between, rows.
You might wonder if all that time spent thinking about germs might make Nicas obsessive about his own hygiene.
"I have a good sense of the risks," concedes Nicas, "probably more than most people. I try not to shake hands with people who have a cold. I tell my son to wash his hands. But I don't Lysol my counter every 10 minutes."

Transparent Aluminum Is ‘New State Of Matter’

Oxford scientists have created a transparent form of aluminium by bombarding the metal with the world’s most powerful soft X-ray laser. ‘Transparent aluminium’ previously only existed in science fiction, featuring in the movie Star Trek IV, but the real material is an exotic new state of matter with implications for planetary science and nuclear fusion.
In the journal Nature Physics an international team, led by Oxford University scientists, report that a short pulse from the FLASH laser ‘knocked out’ a core electron from every aluminium atom in a sample without disrupting the metal’s crystalline structure. This turned the aluminium nearly invisible to extreme ultraviolet radiation.
''What we have created is a completely new state of matter nobody has seen before,’ said Professor Justin Wark of Oxford University’s Department of Physics, one of the authors of the paper. ‘Transparent aluminium is just the start. The physical properties of the matter we are creating are relevant to the conditions inside large planets, and we also hope that by studying it we can gain a greater understanding of what is going on during the creation of 'miniature stars' created by high-power laser implosions, which may one day allow the power of nuclear fusion to be harnessed here on Earth.’
The discovery was made possible with the development of a new source of radiation that is ten billion times brighter than any synchrotron in the world (such as the UK’s Diamond Light Source). The FLASH laser, based in Hamburg, Germany, produces extremely brief pulses of soft X-ray light, each of which is more powerful than the output of a power plant that provides electricity to a whole city.
The Oxford team, along with their international colleagues, focused all this power down into a spot with a diameter less than a twentieth of the width of a human hair. At such high intensities the aluminium turned transparent.
Whilst the invisible effect lasted for only an extremely brief period – an estimated 40 femtoseconds – it demonstrates that such an exotic state of matter can be created using very high power X-ray sources.
Professor Wark added: ‘What is particularly remarkable about our experiment is that we have turned ordinary aluminium into this exotic new material in a single step by using this very powerful laser. For a brief period the sample looks and behaves in every way like a new form of matter. In certain respects, the way it reacts is as though we had changed every aluminium atom into silicon: it’s almost as surprising as finding that you can turn lead into gold with light!’
The researchers believe that the new approach is an ideal way to create and study such exotic states of matter and will lead to further work relevant to areas as diverse as planetary science, astrophysics and nuclear fusion power.
A report of the research, ‘Turning solid aluminium transparent by intense soft X-ray photoionization’, is published in Nature Physics. The research was carried out by an international team led by Oxford University scientists Professor Justin Wark, Dr Bob Nagler, Dr Gianluca Gregori, William Murphy, Sam Vinko and Thomas Whitcher.

Scientists Capitalize On Extended Solar Eclipse

On Wednesday, 2009 July 22, a total eclipse of the Sun is visible from within a narrow corridor that traverses half of Earth. The path of the Moon's umbral shadow begins in India and crosses through Nepal, Bangladesh, Bhutan, Myanmar and China. After leaving mainland Asia, the path crosses Japan's Ryukyu Islands and curves southeast through the Pacific Ocean where the maximum duration of totality reaches 6 min 39 s. A partial eclipse is seen within the much broader path of the Moon's penumbral shadow, which includes most of eastern Asia, Indonesia, and the Pacific Ocean.

The moon's shadow traced a path across the world's two most populous countries before racing across the Pacific, providing a view of totality for five minutes and 36 seconds for scientists gathered here from around the world as part of the Williams College Eclipse Expedition.
"We saw it! The clouds kept getting thinner, and we even had a pretty good-sized hole in the clouds for the five minutes of totality," reported Expedition Leader Jay Pasachoff, Field Memorial Professor of Astronomy at Williams and chair of the International Astronomical Union's Working Group on Solar Eclipses.
"Everyone saw all the coronal phenomena. The diamond rings were spectacular. Just before totality, the clouds were just the right thickness that allowed us to see partial phases without filters.
"All our equipment seems to have worked, so now we still have an hour or so of partial eclipse to image, and then we will download photos and start looking at them. The oscillation experiment has a lot of data through two filters, and we will assess later whether comparison of the two channels allow us to account for the cloud cover," Pasachoff said by email from China.
He was observing his 49th solar eclipse.
Pasachoff and his colleagues are capturing data over many eclipses to understand better why the Sun's corona, the outer halo of million-degree gas, shines hotter than the Sun itself. Most of the corona is visible from Earth only for the fleeting time that the moon totally blocks the Sun's direct rays.
They use a special rapid-readout electronic camera and single-color filters chosen to show only coronal gas, looking for oscillations with periods in the range of one second, which would signify certain classes of magnetic waves. The detailed structure of the corona, revealed by imaging in the visible and x-ray regions of the spectrum, and the correspondence of bright coronal regions with sunspot groups, shows that magnetism is the cause of coronal heating and the coronal structure. Competing explanations involve relatively tiny solar flares going off all the time.
Pasachoff's work with Miloslav Druckmuller of the Brno Institute of Technology in the Czech Republic and with Vojtech Rusin and Metod Saniga of the solar observatory in Slovakia has led to several joint papers in the Astrophysical Journal on views of the changing corona.
The expedition includes Bryce Babcock, staff physicist, and several undergraduate students from Williams and has been supported mainly by a grant from the Committee for Research and Exploration of the National Geographic Society.
The next total eclipse of the Sun, on July 11, 2010, will occur in the South Pacific and hit land only in the Cook Islands, Easter Island, and a small section of southern Chile and Argentina.

Cosmic Meddling With The Clouds By Seven-day Magic

Billions of tonnes of water droplets vanish from the atmosphere, as if by magic, in events that reveal in detail how the Sun and the stars control our everyday clouds. Researchers have traced the consequences of eruptions on the Sun that screen the Earth from some of the cosmic rays - the energetic particles raining down on our planet from exploded stars.

"The Sun makes fantastic natural experiments that allow us to test our ideas about its effects on the climate," says Prof. Henrik Svensmark, lead author of a report newly published in Geophysical Research Letters. When solar explosions interfere with the cosmic rays there is a temporary shortage of small aerosols, chemical specks in the air that normally grow until water vapour can condense on them, so seeding the liquid water droplets of low-level clouds. Because of the shortage, clouds over the ocean can lose as much as 7 per cent of their liquid water within seven or eight days of the cosmic-ray minimum.
"A link between the Sun, cosmic rays, aerosols, and liquid-water clouds appears to exist on a global scale," the report concludes. This research, to which Torsten Bondo and Jacob Svensmark contributed, validates 13 years of discoveries that point to a key role for cosmic rays in climate change. In particular, it connects observable variations in the world's cloudiness to laboratory experiments in Copenhagen showing how cosmic rays help to make the all-important aerosols.
Other investigators have reported difficulty in finding significant effects of the solar eruptions on clouds, and Henrik Svensmark understands their problem. "It's like trying to see tigers hidden in the jungle, because clouds change a lot from day to day whatever the cosmic rays are doing," he says. The first task for a successful hunt was to work out when "tigers" were most likely to show themselves, by identifying the most promising instances of sudden drops in the count of cosmic rays, called Forbush decreases. Previous research in Copenhagen predicted that the effects should be most notice-able in the lowest 3000 metres of the atmosphere. The team identified 26 Forbush decreases since 1987 that caused the biggest reductions in cosmic rays at low altitudes, and set about looking for the consequences.

Evidence Of Liquid Water In Comets Reveals Possible Origin Of Life

Comet Hale-Bopp. The watery environment of early comets, together with the vast quantity of organics already discovered in comets, would have provided ideal conditions for primitive bacteria to grow and multiply, experts argue.

Comets have contained vast amounts of liquid water in their interiors during the first million years of their formation, a new study claims.

The watery environment of early comets, together with the vast quantity of organics already discovered in comets, would have provided ideal conditions for primitive bacteria to grow and multiply. So argue Professor Chandra Wickramasinghe and his colleagues at the Cardiff Centre for Astrobiology in a paper published in the International Journal of Astrobiology.
The Cardiff team has calculated the thermal history of comets after they formed from interstellar and interplanetary dust approximately 4.5 billion years ago. The formation of the solar system itself is thought to have been triggered by shock waves that emanated from the explosion of a nearby supernova. The supernova injected radioactive material such as Aluminium-26 into the primordial solar system and some became incorporated in the comets. Professor Chandra Wickramasinghe together with Drs Janaki Wickramasinghe and Max Wallis claim that the heat emitted from radioactivity warms initially frozen material of comets to produce subsurface oceans that persist in a liquid condition for a million years.
Professor Wickramasinghe said: "These calculations, which are more exhaustive than any done before, leaves little doubt that a large fraction of the 100 billion comets in our solar system did indeed have liquid interiors in the past.
Comets in recent times could also liquefy just below their surfaces as they approach the inner solar system in their orbits. Evidence of recent melting has been discovered in recent pictures of comet Tempel 1 taken by the "Deep Impact" probe in 2005."
The existence of liquid water in comets gives added support for a possible connection between life on Earth and comets. The theory, known as cometary panspermia, pioneered by Chandra Wickramasinghe and the late Sir Fred Hoyle argues the case that life was introduced to Earth by comets.

Crashing Comets Not Likely The Cause Of Earth's Mass Extinctions

A long-period comet called 2001 RX14 (Linear) turned up in images captured in 2002 by the Sloan Digital Sky Survey telescope in New Mexico.

Scientists have debated how many mass extinction events in Earth's history were triggered by a space body crashing into the planet's surface. Most agree that an asteroid collision 65 million years ago brought an end to the age of dinosaurs, but there is uncertainty about how many other extinctions might have resulted from asteroid or comet collisions with Earth.
In fact, astronomers know the inner solar system has been protected at least to some degree by Saturn and Jupiter, whose gravitational fields can eject comets into interstellar space or sometimes send them crashing into the giant planets. That point was reinforced July 20 when a huge scar appeared on Jupiter's surface, likely evidence of a comet impact.
New University of Washington research indicates it is highly unlikely that comets have caused any mass extinctions or have been responsible for more than one minor extinction event. The work also shows that many long-period comets that end up in Earth-crossing orbits likely originate from a region astronomers have long believed could not produce observable comets. A long-period comet takes from 200 years to tens of millions of years to make a single orbit of the sun.

Discovering A New Earth 430 Light Years Away

Astronomers Spy Earth-like Planet Forming Around Distant Star

Astrophysicists analyzing infrared images captured by the Spitzer Space Telescope found indications of a dust cloud surrounding a relatively young star. The star is 10 to 16 million years old, and analysis of the dust cloud suggests that it may coalesce and become a rocky planet like earth. It is located at a distance from the star that it may build an atmosphere, collect liquid water, and perhaps, in millions and millions of years, support life.

It took billions of years and the perfect conditions for our Earth to grow and form. Now, those same conditions can be seen in space, shaping a similar planet. Ivanhoe explains this exciting space discovery.
Far, far away, something amazing is brewing in space. Swirling around a giant star similar to our sun, astrophysicists have spotted the very early stages of a planet taking shape.
"What we think we're seeing is the actual formation of a planet -- terrestrial planet -- a rocky planet like the Earth, around the star," Carey Lisse, Ph.D., a senior research scientist at Johns Hopkins Applied Physics Laboratory in Laurel, Md., told Ivanhoe.
The Earth-like planet is about 430 light years away or 2.5x1015 miles from Earth. It's inside a huge dust belt -- bigger than our asteroid belt -- with enough dusty material to build a planet. "The material is forming at just the same distance, or close to the same distance where the Earth formed from the sun," Dr. Lisse says.
To find the planet, astronomers used images captured by the Spitzer Space Telescope. It looks for infrared light or heat radiating from the dusty materials. The images also confirm the rocky fragments forming the new planet are similar to materials found in the Earth's crust and core.
"So, the body that's going to form -- the planet that's going to form -- isn't going to be this gas giant with incredibly thick atmosphere," explains Dr. Lisse. It's going to be a rocky planet like Mars or Venus or the Earth."
There's also an outer ice belt circling the young planet, making it more likely that water could reach the new planet's surface … and maybe even life; but don't wait around for signs of life. The planet still needs another 100 million years before it's completely formed.
Astronomers say the star the new planet is spinning around is between ten and 16 million years old, which is the perfect age for forming Earth-like planets.

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ABOUT THE SPITZER TELESCOPE: The Spitzer Space Telescope was launched on 25 August 2003. Spitzer detects the infrared energy radiated by objects in space. Most of this infrared radiation is blocked by the Earth's atmosphere and cannot be observed from the ground. Spitzer allows us to peer into regions of space that are hidden from optical telescopes.
Many areas of space are filled with vast, dense clouds of gas and dust that block our view. Infrared light, however can penetrate these clouds, allowing us to peer into regions of star formation, the centers of galaxies, and into newly forming planetary systems. Infrared also brings us information about the cooler objects in space, such as smaller stars which are too dim to be detected by their visible light, extrasolar planets, and giant molecular clouds. Also, many molecules in space, including organic molecules, have their unique signatures in the infrared.
WHAT IS INFRARED LIGHT? Infrared radiation is an invisible form of light that we usually detect as heat, like the sun shining on our face, or the warmth of a campfire. It has all the same properties as visible light: for example, it can be focused and reflected. The only difference is that it has a longer wavelength, which means we can't see it with the naked eye. Light is made of tiny particles called photons, and the wavelength tells us how fast those particles are vibrating. The shorter the wavelength, the faster the particles are moving. Shorter light waves look blue, and longer ones look red.
The wavelength of infrared light is so long that we can't see it at all. Any warm object gives off infrared radiation. By checking in the infrared spectrum, engineers can find heat leaks in buildings, doctors can find hidden tumors in the body, and biologists can locate diseased plants in a forest. Astronomers use infrared imaging to detect warm dust around new stars that are not yet "hot" enough to emit visible light.
The American Astronomical Society and the American Geophysical Union contributed to the information contained in the video portion of this report.