First Fully-functional Radio From A Single Carbon Nanotube Created

Daily Science Journal (Oct. 31, 2007) — Make way for the real nanopod and make room in the Guinness World Records. A team of researchers with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley have created the first fully functional radio from a single carbon nanotube, which makes it by several orders of magnitude the smallest radio ever made.

This image, taken by a transmission electron microscope, shows a single carbon nanotube protruding from an electrode. This nanotube is less than a micron long and only 10 nanometers wide, or 10,000 times thinner than the width of a single human hair. When a radio wave of a specific frequency impinges on the nanotube, it begins to vibrate vigorously. An electric field applied to the nanotube forces electrons to be emitted from its tip. This electrical current may be used to detect the mechanical vibrations of the nanotube, and thus listen to the radio waves. (The waves shown in this image were added for visual effect, and are not part of the original microscope image.) (Credit: Courtesy Zettl Research Group, Lawrence Berkeley National Laboratory and University of California at Berkeley)

Wielding a single carbon nanotube 10,000 times smaller than a human hair, this is definitely the smallest radio yet. The nanotube vibrates at radio frequencies to receive the signal, then acts as both amplifier and demodulator. With only a battery and sensitive earphones, it can pick up AM or FM. With such a small receiver or transmitter, you could put a tracking collar on a bacterium.

“A single carbon nanotube molecule serves simultaneously as all essential components of a radio — antenna, tunable band-pass filter, amplifier, and demodulator,” said physicist Alex Zettl, who led the invention of the nanotube radio. “Using carrier waves in the commercially relevant 40-400 MHz range and both frequency and amplitude modulation (FM and AM), we were able to demonstrate successful music and voice reception.”

Given that the nanotube radio essentially assembles itself and can be easily tuned to a desired frequency band after fabrication, Zettl believes that nanoradios will be relatively easy to mass-produce. Potential applications, in addition to incredibly tiny radio receivers, include a new generation of wireless communication devices and monitors. Nanotube radio technology could prove especially valuable for biological and medical applications.

“The entire radio would easily fit inside a living cell, and this small size allows it to safely interact with biological systems,” Zettl said. “One can envision interfaces with brain or muscle functions, or radio-controlled devices moving through the bloodstream.”

It is also possible that the nanotube radio could be implanted in the inner ear as an entirely new and discrete way of transmitting information, or as a radically new method of correcting impaired hearing.

Zettl holds joint appointments with Berkeley Lab's Materials Sciences Division (MSD) and the UC Berkeley Physics Department where he is the director of the Center of Integrated Nanomechanical Systems. In recent years, he and his research group have created an astonishing array of devices out of carbon nanotubes - hollow tubular macromolecules only a few nanometers (billionths of a meter) in diameter and typically less than a micron in length – including sensors, diodes and even a motor. The nanotube radio, however, is the first that – literally – rocks!

“When I was a young kid, I got a transistor radio as a gift and it was the greatest thing I could imagine - music coming from a box I could hold in my hand!” Zettl said. “When we first played our nanoradio, I was just as excited as I was when I first turned on that transistor radio as a kid.”

The carbon nanotube radio consists of an individual carbon nanotube mounted to an electrode in close proximity to a counter-electrode, with a DC voltage source, such as from a battery or a solar cell array, connected to the electrodes for power. The applied DC bias creates a negative electrical charge on the tip of the nanotube, sensitizing it to oscillating electric fields. Both the electrodes and nanotube are contained in vacuum, in a geometrical configuration similar to that of a conventional vacuum tube.

Kenneth Jensen, a graduate student in Zettl’s research group, did the actual design and construction of the radio.

“We started out by making an exceptionally sensitive force sensor,” Jensen said.“Nanotubes are like tiny cat whiskers.Small forces, on the order of attonewtons, cause them to deflect a significant amount.By detecting this deflection, you can infer what force was acting on the nanotube. This incredible sensitivity becomes even greater at the nanotube’s flexural resonance frequency, which falls within the frequencies of radio broadcasts, cell phones and GPS broadcasting. Because of this high resonance frequency, Alex (Zettl) suggested that nanotubes could be used to make a radio.”

Although it has the same essential components, the nanotube radio does not work like a conventional radio. Rather than the entirely electrical operation of a conventional radio, the nanotube radio is in part a mechanical operation, with the nanotube itself serving as both antenna and tuner.

Incoming radio waves interact with the nanotube’s electrically charged tip, causing the nanotube to vibrate. These vibrations are only significant when the frequency of the incoming wave coincides with the nanotube’s flexural resonance frequency, which, like a conventional radio, can be tuned during operation to receive only a pre-selected segment, or channel, of the electromagnetic spectrum.

Amplification and demodulation properties arise from the needle-point geometry of carbon nanotubes, which gives them unique field emission properties. By concentrating the electric field of the DC bias voltage applied across the electrodes, the nanotube radio produces a field-emission current that is sensitive to the nanotube’s mechanical vibrations. Since the field-emission current is generated by the external power source, amplification of the radio signal is possible. Furthermore, since field emission is a non-linear process, it also acts to demodulate an AM or FM radio signal, just like the diode used in traditional radios.

“What we see then is that all four essential components of a radio receiver are compactly and efficiently implemented within the vibrating and field-emitting carbon nanotube,” said Zettl. “This is a totally different approach to making a radio - the exploitation of electro-mechanical movement for multiple functions. In other words, our nanotube radio is a true NEMS (nano-electro-mechanical system) device.”

Because carbon nanotubes are so much smaller than the wavelengths of visible light, they cannot be viewed with even the highest powered optical microscope. Therefore, to observe the critical mechanical motionof their nanotube radio, Zettl and his research team, which in addition to Jensen, also included post-doc Jeff Weldon and graduate student Henry Garcia, mounted their nanotube radio inside a high resolution transmission electron microscope (TEM). A sine-wave carrier radio signal was launched from a nearby transmitting antenna and when the frequencies of the transmitted carrier wave matched the nanotube resonance frequency, radio reception became possible.

“To correlate the mechanical motions of the nanotube to an actual radio receiver operation, we launched an FM radio transmission of the song Good Vibrations by the Beach Boys,” said Zettl. “After being received, filtered, amplified, and demodulated all by the nanotube radio, the emerging signal was further amplified by a current preamplifier, sent to an audio loudspeaker and recorded. The nanotube radio faithfully reproduced the audio signal, and the song was easily recognizable by ear.”

When the researchers deliberately detuned the nanotube radio from the carrier frequency, mechanical vibrations faded and radio reception was lost. A “lock” on a given radio transmission channel could be maintained for many minutes at a time, and it was not necessary to operate the nanotube radio inside a TEM. Using a slightly different configuration, the researchers successfully transmitted and received signals across a distance of several meters.

“The integration of all the electronic components of a radio happened naturally in the nanotube itself,” said Jensen. “Within a few hours of figuring out that our force sensor was in fact a radio, we were playing music!”

Added Zettl, “Our nanotube radio is sophisticated and elegant in the physics of its operation, but sheer simplicity in technical design. Everything about it works perfectly, without additional patches or tricks.”

Berkeley Lab’s Technology Transfer Department is now seeking industrial partners to further develop and commercialize this technology.

A paper on this work is now on-line at the Nano Letters Website. It will also be published in the November 2007 print edition of Nano Letters. The paper is entitled “Nanotube Radio” and the co-authors are Zettl, Jensen, Weldon and Garcia. In that same print edition, there appears a paper by Peter Burke and Chris Rutherglen of UC Irvine, reporting on the use of a carbon nanotube as a demodulator.

The nanotube radio research was supported by the U.S. Department of Energy and by the National Science Foundation within the Center of Integrated Nanomechanical Systems.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California.

Adapted from materials provided by DOE/Lawrence Berkeley National Laboratory.

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Women With Breast Cancer Have Less Dermatitis When Treated With IMRT

Daily Science Journal (Oct. 30, 2007) — All women treated with radiation therapy for breast cancer are at risk of developing dermatitis--a sometimes-painful skin condition caused by radiation as it makes its way through the skin to the tumor area and tissue within the breast. But researchers at Fox Chase Cancer Center say women being treated with IMRT (intensity-modulated radiation therapy) are less likely to have serious dermatitis.

A reddening of the skin, dermatitis is often likened to a bad sunburn. It can begin in the first weeks of treatment as mild redness, dryness or itching of the skin and progress to a more intense skin reaction by the last week of radiation. When dermatitis is acute and severe, causing peeling, it is can be extremely painful, interfering with normal life activities and sometimes interrupting treatment.

"Dermatitis is a major quality-of-life concern," said Gary Freedman, M.D., a radiation oncologist at Fox Chase Cancer Center who studies the side effects of breast cancer treatment. "It can be so painful that wearing a bra or snug-fitting clothing isn't possible. In the most severe cases, the skin will actually bleed or be at risk of infection."

Freedman says IMRT can reduce the risk of dermatitis. IMRT allows the radiation to be distributed in more beams across the skin, avoiding the full-on assault of conventional radiation.

In this study, Freedman and his colleagues looked at the records of 804 consecutive patients with early-stage breast cancer. The women were treated with breast-conserving surgery and radiation therapy between 2001 and 2006.

In the earlier part of the study period, women were treated with conventional radiation therapy (n=405). Later in the study period, women were primarily treated with IMRT (n=399).

Of those treated with IMRT, 48 percent had grade 0/1 dermatitis and 52 percent had grade 2/3. Of those treated with conventional radiation, 25 percent had grade 0/1 dermatitis and 75 percent had grade 2/3.

"In addition to statistically fewer patients with serious dermatitis, women treated with IMRT who developed dermatitis had it for a shorter time period than those treated with conventional radiation," added Freedman. "These benefits were shown in all patients regardless of breast size."

He concluded, "This study confirms our current practice of recommending IMRT for all patients. The study seeks to provide further evidence for patients, physicians and insurance companies that IMRT should be standard practice."

The research was presented October 28, 2007 at the American Society for Therapeutic Radiology and Oncology's 49th Annual Meeting in Los Angeles.

Fox Chase Cancer Center was founded in 1904 in Philadelphia as the nation's first cancer hospital. In 1974, Fox Chase became one of the first institutions designated as a National Cancer Institute Comprehensive Cancer Center. Fox Chase conducts basic, clinical, population and translational research; programs of cancer prevention, detection and treatment; and community outreach. For more information about Fox Chase activities, visit the Center's web site at http://www.fccc.edu or call 1-888-FOX CHASE.

Adapted from materials provided by Fox Chase Cancer Center, via EurekAlert!, a service of AAAS.

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Kinsey Study Finds Adverse Sexual, Emotional Side Effects Of Birth Control Pills

Daily Science Journal (Oct. 25, 2007) — BLOOMINGTON, Ind. -- The birth control pill can have significant adverse effects on sexuality and mood in some women, increasing the likelihood of early discontinuation, according to a study by the Kinsey Institute for Research in Sex, Gender and Reproduction at Indiana University. Results of the study will be reported in the July issue of the journal Contraception.

Stephanie Sanders, associate director of the Kinsey Institute and an IU faculty member in gender studies, directed the study of 80 women. The research team included John Bancroft and Jennifer Bass of the Kinsey Institute and Cynthia Graham of the IU Department of Psychology.

Of the women in the study who started on the pill (randomly assigned to either orthocyclen or orthotricyclen), 38 percent were still taking it after one year, 47 percent had stopped, and 14 percent had switched to another pill. The women who stopped or changed to another pill were four times as likely to report adverse sexual, emotional and physical side effects as the women who continued with their oral contraceptive. Some of these effects included decrease in sexual thoughts, less frequent intercourse and negative mood changes.

"It is clear in our results that the women who stopped or changed to another pill had more sexual, emotional and physical side effects than the women who continued with their oral contraceptive," Sanders said.

The authors noted that, despite 40 years of use, there is no way of predicting which women are likely to experience adverse mood or sexuality effects from oral contraceptives, or which oral contraceptive formulations are more likely to be responsible.

"Studies on the male contraceptive pill, still in the developmental phase, have already included evaluation of possible effects on sexuality, but women have not had the benefit of such information in making contraceptive decisions," Sanders said.

The authors called for further research to identify predictors of such adverse effects and to understand the hormonal mechanisms responsible for such effects. In the meantime, they said, women should be fully informed, and clinicians should discuss potential effects of oral contraceptives on sexuality and mood with their patients.

Adapted from materials provided by Indiana University.

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Online Multiplayer Video Games Create Greater Negative Consequences, Elicit Greater Enjoyment than Traditional Ones

Daily Science Journal (Oct. 22, 2007) — Online video games with thousands of simultaneous players, such as “World of Warcraft,” have become hugely popular in the last two decades and are now a multibillion dollar industry with tremendous financial success. Joshua Smyth, associate professor of psychology in The College of Arts and Sciences at Syracuse University, recently conducted a randomized trial study of college students contrasting the effects of playing online socially interconnected video games with more traditional single-player or arcade-style games.

Playing online multiplayer games had much greater positive and negative effects on people than playing traditional single-player video games, a new study has found. (Credit: iStockphoto/Charles Benavidez)

While both multiplayer and traditional single player video games present a double-edged sword, Smyth’s research found that online, socially integrated multiplayer games create greater negative consequences (decreased health, well-being, sleep, socialization and academic work) but also garner far greater positive results (greater enjoyment in playing, increased interest in continuing play and a rise in the acquisition of new friendships) than do single-player games.

“The most striking result of this study is that playing online multiplayer games had much greater positive and negative effects on people than playing traditional single-player video games,” says Smyth. “Students in the study who played online multiplayer games did so about three times as much as those playing single-player game types, averaging over 14 hours a week.”

In his study, Smyth randomly assigned 100 college student volunteers to play one of four types of video games: traditional, arcade-style games (such as those found in the local mall); console games like the Sony PlayStation; single player computer games; and fantasy-themed persistent online multiplayer games.

Computer networking—linking players from across the world together in a single game—has dramatically changed the nature of video game play from a solitary activity into a large, thriving social experience. Multiplayer online role-play gaming, one type of social gaming, can involve thousands of players in persistent virtual worlds.

All students taking part in the study reported decreased health and sleep and interference with real-life socializing and academic work. In contrast to these costs, participants experienced benefits, most notably by those taking part in online multiplayer game play. Online multiplayer gamers enjoyed their play far more than those assigned to more traditional game types, creating new friendships in their online environments.

“Video game play does interfere in some aspects of real-life — such as academic performance, health and social life — but game play can also foster strong feelings of virtual support and new friendships,” Smyth says.

The study is published in the October 2007 issue of the bimonthly peer-reviewed journal CyberPyschology & Behavior (Vol. 10, No. 5: 717–721).

Adapted from materials provided by Syracuse University, via Newswise.

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Herbal, Nutritional Supplements Linked To Ocular Side Effects

Daily Science Journal (Oct. 22, 2007) — An estimated 42 percent of Americans use herbal medicines or nutritional supplements. Many people taking these products and their physicians are unaware of the adverse reactions they can cause. An Oregon Health & Science University researcher reviewed reported cases of ocular side effects associated with these products. His findings are published in the American Journal of Ophthalmology this month.

The researcher, Frederick W. Fraunfelder, M.D., assistant professor of ophthalmology in the OHSU School of Medicine and the OHSU Casey Eye Institute, found side effects ranging from dry eye to retinal hemorrhages and transient visual loss. Most of the side effects were associated with higher doses and topical application. While none of the reported cases caused permanent damage, many could have if the patient had not discontinued use of the product.

"A large segment of the population uses herbal medicines and nutritional supplements, many times without the treating physician's knowledge," said Fraunfelder, who also is director of the National Registry of Drug-Induced Ocular Side Effects based at the Casey Eye Institute. "These products can cause ocular side effects and clinicians need to recognize these adverse events."

Herbal medicines and nutritional supplements are not regulated by the Food and Drug Administration (FDA) as prescription and over-the-counter medications are. The World Health Organization (WHO) published guidelines on the use of herbal medicines in 2004, including recommendations on cultivating, collecting, classification, quality control, storage, labeling and distribution. However, there are no official standards governing the production of herbal medicines in the United States and the potency and purity of these products vary widely.

Fraunfelder reviewed cases of adverse ocular side effects reported to the WHO, the FDA and the National Registry of Drug-Induced Ocular Side Effects, and reviewed world literature for reported instances of adverse ocular side effects caused by herbal medicines and nutritional supplements. Out of 323 reported cases he found eight products associated with clinically significant ocular side effects: ginkgo biloba, Echinacea purpurea, chamomile, licorice, canthaxanthine, Datura, niacin and vitamin A.

One of the best-selling herbal medicines in the United States and worldwide is ginkgo biloba, which is used to treat tinnitus, asthma and tonsillitis among other things. Fraunfelder found two cases of hemorrhaging in the anterior chamber of the eye as well as reports of retinal hemorrhages in patients taking this agent. Ginkgo biloba inhibits platelet aggregation, and should be used with caution in patients taking aspirin because the effects could be amplified. Echinacea purpurea is used to treat colds, coughs, fevers, urinary tract infections, burns and influenza. Reports of eye irritation and conjunctivitis have been associated with its topical use.

Chamomile is used to treat eye disease as well as insomnia, indigestion, migraine headaches, bronchitis, fevers, colds, inflammation and burns. Chamomile tea is used by some topically in and around the eyes to treat styes and runny, irritated eyes. Fraunfelder found reported cases of severe conjunctivitis related to chamomile's topical use.

Licorice is used to treat upper respiratory tract infections, ulcers, appendicitis and constipation. American Indians use licorice to treat inflammatory eye diseases. Fraunfelder found cases of transient vision loss after licorice ingestion, similar to what one might see with an ocular migraine without headache. The side effects appear to be associated with large doses.

Canthaxanthine, a carotenoid used in cosmetics, as a food coloring and to produce an artificial suntan when taken orally, causes deposits of the drug in the retina. The deposits appear to be absorbed over time, but take years to disappear. Visual changes from this nutritional supplement are related to retinal abnormalities detected with visual field testing and electroretinography (a test of retinal function).

Jimson Weed is the most common member of the genus Datura. The dried leaves of this flower are used to treat eye inflammation as well as asthma, bronchitis, influenza and coughs. Fraunfelder found several instances of mydriasis, a prolonged dilation of the pupil.

Niacin can cause some of the most severe ocular reactions of all the products reviewed. Its cholesterol-lowering effects have proved successful in treating cardiovascular and cerebrovascular disease. It also is used for treatment of schizophrenia, diabetes, arthritis, hypertension, sexual dysfunction and migraine headaches. A comprehensive review of ocular side effects from niacin indicates a possible association with decreased vision, cystoid macular edema (CME), dry eyes, discoloration of the eyelids, eyelid edema and loss of eyebrows and eyelashes, among others. The ocular side effects appear to be dose related, but some instances would require discontinuation of niacin therapy.

Vitamin A is used primarily as an oral dietary supplement for vitamin A deficiency and for treatment of acne. Fraunfelder found reports linking high doses of vitamin A to cases of intracranial hypertension. In the majority of cases this condition resolves when vitamin A is discontinued.

Many herbal medicines interact with prescription medicines, and if the treating physician doesn't know what a patient is taking, it can be detrimental. For example, a patient taking ginkgo biloba plus aspirin or a nonsteroidal anti-inflammatory medication such as ibuprofen, may thin the blood too much, leading to ocular hemorrhage or even intracranial hemorrhage.

"Herbal medicines and nutritional supplements are being used without strong evidence of efficacy or safety. Ocular side effects from these products are often undiagnosed and unreported," said Fraunfelder. "Physicians must remain vigilant in recognizing adverse ocular side effects and inquiring whether a patient is using alternative therapies."

This study was supported in part by a grant from Research to Prevent Blindness.

Adapted from materials provided by Oregon Health & Science University.

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Emergency Contraception Does Not Reduce Unintended Pregnancy Rate

Daily Science Journal (Oct. 20, 2007) — The "morning after pill" may be a good option for individual women in crisis, but advance access to emergency contraception is no antidote for the national problem of unintended pregnancy. Contrary to the fears of critics, the presence of Plan B does not provoke riskier sexual behavior.

According to a new review of studies, women who received an advance supply of birth control pills for emergency contraception had an equal chance of becoming pregnant as women who did not have early access to the pills.

The review draws conclusions from eight studies of more than 6,000 women in the United States, India and China.

Plan B is a well-known brand of emergency contraception pills, but many different types of birth control medication taken at higher doses can prevent pregnancy after sex. Treatment must begin within five days after unprotected sex -- and sooner is better when it comes to EC.

"We had expected that easier access to emergency contraception could help women use the pills more quickly when they needed them, and that in turn -- since EC is a time-relevant medication -- this could help women avoid unintended pregnancy," said lead reviewer Chelsea Polis.

"Our review is really about the effectiveness of advance provision as a strategy to reduce unintended pregnancy at a population level," Polis said. "The review is not about the effectiveness of EC; that is a separate matter."

The review appears in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates research in all aspects of health care. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing trials on a topic.

In 2001, about half of pregnancies in the United States were unintended, according to the Centers for Disease Control and Prevention. Now, the United States is working to lower the unintended pregnancy rate to 30 percent by 2010. Princeton University demographer James Trussell says easier access to emergency contraception will not slow the rate of unintended pregnancy in the United States.

"For individual women, it is definitely a last chance to prevent pregnancy after unprotected sex. But it is not going to have a major population impact because people will never use it enough," he said.

The review found that emergency contraception use was higher among women given an advance supply of the birth control pills, but that increase in use did not translate to a drop in the pregnancy rate.

"Even though advance provision increased use, we don't know if women were using EC at the times when they were at risk for pregnancy, when it was really needed," Polis explains.

"If women aren't going to use Plan B when they are given it for free in a clinical trial and are counseled beforehand about using it every single time they have unprotected sex, then having to go to CVS and having to pay $45 each time -- it isn't going to happen," Trussell said.

Nonetheless, Polis said her review is not an argument against easier access to emergency contraception.

"Women deserve the chance to protect themselves from unintended pregnancy and EC is a safe, effective way to do that. Emergencies like rape, contraceptive failure and unprotected sex occur, and easier access to EC eliminates a medically unwarranted barrier to taking emergency contraception within the recommended timeframe," she said. "So steps like making EC available over the counter are still incredibly important."

When advanced access to emergency contraception was first proposed, critics worried that a medicine cabinet stocked with pills to prevent pregnancy would lead some women to be more promiscuous, have riskier sex or not use condoms.

The Cochrane review counters those concerns. "We found there was absolutely no difference in sexually transmitted infection rates between the two groups. There's absolutely no difference in terms of unprotected sex, condom use or changes in use of other contraceptive methods," Polis said. "So it appears that advance provision of EC has no harmful effects in terms of risky sexual behaviors."

Reference: Polis CB, et al. Advance provision of emergency contraception for pregnancy prevention. (Review). Cochrane Database of Systematic Reviews 2007, Issue 2.

Adapted from materials provided by Center for the Advancement of Health.

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You Thought Your Nano Was Small: Nano-sized Detector Turns Radio Waves Into Music

Daily Science Journal (Oct. 19, 2007) — Researchers in California report development of the world's first working radio system that receives radio waves wirelessly and converts them to sound signals through a nano-sized detector made of carbon nanotubes.

The "carbon nanotube radio" device is thousands of times smaller than the diameter of a human hair. The development marks an important step in the evolution of nano-electronics and could lead to the production of the world's smallest radio, the scientists say.

Peter Burke and Chris Rutherglen developed a carbon nanotube "demodulator" that is capable of translating AM radio waves into sound. In a laboratory demonstration, the researchers incorporated the detector into a complete radio system and used it to successfully transmit classical music wirelessly from an iPod to a speaker several feet away from the music player.

Although other researchers have developed nano-sized radio wave detectors in the past, the current study marks the first time that a nano-sized detector has been demonstrated in an actual working radio system, the scientists say. The study demonstrates the feasibility of making other radio components at the nanoscale in the future and may eventually lead to a "truly integrated nanoscale wireless communications system," they say. Such a device could have numerous industrial, commercial, medical and other applications.

Their findings appeared online October 17 and are scheduled for publication in the Nov. 14 print edition of ACS' Nano Letters.

Adapted from materials provided by American Chemical Society, via EurekAlert!, a service of AAAS.

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Double Star TC-1 Completes Its Mission ; Details Of Solar Particles Penetrating The Earth's Environment Revealed

Daily Science Journal (Oct. 19, 2007) — TC-1, one of the two satellites of the CNSA/ESA Double Star mission, was decommissioned on 14 October as its designed orbit lifetime came to an end. The satellite re-entered Earth’s atmosphere and turned to dust during its descent.

Flying in formation around the Earth, they relay detailed information about how solar wind affects our planet in 3D. The satellites are called Rumba, Salsa, Samba and Tango. (Credit: ESA)

Along with its twin TC-2, TC-1 is the first satellite built and operated by the Chinese National Space Administration (CNSA) in cooperation with ESA. Along with its twin and the four Cluster satellites, TC-1 has helped accomplish much during its lifetime.

The four years during which Double Star was operational brought in new perspectives concerning the boundaries of the magnetosphere and the fundamental processes that are playing a role in the transport of mass, momentum and energy into the magnetosphere. Thanks to the measurements of TC-1, there was a chance to observe the evolution of structures and physical processes at small scales with Cluster, and then on large scales with Double Star.

Here we list some of the most interesting results where TC-1 played a crucial role.

Space is fizzy

Above our heads, at the bow shock, where the Earth’s magnetic field meets the constant stream of gas from the Sun, thousands of bubbles of superheated gas, or ion density holes, are constantly growing and popping. These bubbles were discovered by Cluster and Double Star together, and the discovery allowed scientists to better understand the interaction between the solar wind and the Earth’s magnetic field.

Celestial chorus further away

Chorus emissions are waves naturally generated in space close to the magnetic equator. They play an important role in creating killer electrons that can damage solar panels and electronic equipments of satellites and are a hazard for astronauts. It was found that these waves are created further away from Earth during high geomagnetic activity. This information is crucial to be able to forecast their impact.

Oscillations of Earth’s natural cloak of magnetism

The four Cluster satellites and TC-1 unexpectedly found themselves engulfed by waves of electrical and magnetic energy as they travelled through Earth’s night-time shadow. Something had set the tail of Earth’s natural cloak of magnetism oscillating, like waves created by a boat travelling across a lake. The data collected gave scientists an important clue to the effects of space weather on Earth’s magnetic field.

"Double Star has demonstrated mutual benefit and fostered scientific cooperation in space research between China and Europe. But there is still much more to come as the full, high-resolution data archive becomes available," says Philippe Escoubet, ESA’s Cluster and Double Star Project Scientist.

Adapted from materials provided by European Space Agency.

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Details Of Solar Particles Penetrating The Earth's Environment Revealed

Co-ordinated efforts by China/ESA’s Double Star and ESA’s Cluster spacecraft have allowed scientists to zero in on an area where energetic particles from the Sun are blasting their way through the Earth’s magnetic shield. Solar material penetrating the Earth's magnetic shield can represent a hazard to both astronauts and satellites.

This sketch shows the orbits of the Cluster and Double Star (TC-1) spacecraft on 8 May 2004, when the five satellites observed magnetic channels created by the merging of the Sun and the Earth's magnetic fields. Such events, called 'Flux Transfer Events,' allow solar particles to break through the Earth's magnetic shield and penetrate the Earth's environment. (Image courtesy of European Space Agency)

On 8 May 2004, one of the two Double Star satellites (TC-1) and all four Cluster spacecraft found themselves in the firing line. For about 6 hours, the Cluster spacecraft were buffeted every 8 minutes by intense flows of electrically charged particles released by the Sun. The Double Star TC-1 spacecraft had it even rougher, being blasted every four minutes for eight hours.

During such events, magnetic channels created by the merging of the Sun and the Earth’s magnetic fields allow solar particles to break through the Earth’s magnetic shield and penetrate the Earth’s environment. Physicists call the occurrence of these magnetic channels Flux Transfer Events. Each magnetic channel appears like a curve shaped tube that can be anything from 5000 to 25000 kilometres in diameter. One end of the magnetic flux tube is connected to Earth while the other end is connected to the solar wind.

The basic physical mechanism responsible for the occurrence of flux transfer events is called magnetic reconnection. In the 1950s, space physicists believed that magnetic reconnection let solar particles break through at a steady rate. That view changed in the late 1970s, when several studies showed that the magnetic reconnection could also be intermittent and take place in pulses, lasting a few minutes. Each pulse produces a magnetic flux tube (a Flux Transfer Event).

On 8 May 2004, these magnetic flux tubes swept over Cluster and Double Star again and again. As the Cluster and Double Star data clearly showed, the same location underwent magnetic reconnection several times, creating new successive magnetic flux tubes to channel more charged particles towards the Earth. The observations stopped probably because the spacecraft moved out of range and not because the reconnection region weakened in any way.

The data from the five spacecraft allowed scientists led by Aurélie Marchaudon of the Laboratoire de Physique et Chimie de l’Environnement, Centre Nationale de la Recherche Scientifique (CNRS) and Université d’Orléans, Orléans, France to triangulate the location of the magnetic reconnection region, and to deduce its size. They found that the reconnection site was located on the daylight west side of the Earth’s magnetic shield and was around 25000 kilometres across. A computer simulation of the event, conducted by Jean Berchem of the University of California Los Angeles (UCLA) and his team, confirmed the possibility of magnetic reconnection occurring at that location.

Although intermittent reconnection has been observed in the past, this was one of the longest series of continuous observations ever taken of a magnetic reconnection region in the Earth’s magnetosphere. Perhaps most surprising is that 8 May 2004 was just relatively a normal day for the Earth’s magnetic field. There were no large magnetic storms on Earth, or spectacular aurorae to fill the night sky. However, Cluster and Double Star revealed that energetic particles from the Sun were blasting their way through the Earth’s magnetic shield and penetrating the Earth’s environment.

Each day, Cluster and Double Star return more observations that allow scientist to understand the invisible magnetic turbulence high above our heads.

Adapted from materials provided by European Space Agency.

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Newly Identified Antibody May Neutralize Inhalation Anthrax Toxin

Daily Science Journal (Oct. 19, 2007) — A newly identified antibody capable of neutralizing the inhalation anthrax toxin in rabbits and monkeys may offer an alternative method of preventing and treating infection in humans say US researchers. Their findings appear in the October 2007 issue of the journal Infection and Immunity.

The intentional use of Bacillus anthracis, the causative agent of anthrax, continues to pose serious threat as a bioterrorism or biowarfare agent. Although vaccines currently available are highly effective, multiple doses are required therefore necessitating antibiotic therapy for those individuals exposed prior to scheduled completion.

Monoclonal antibodies (MAb) are derived from one clone of cells, recognize only one antigen (the protective antigen (PA) component of the anthrax toxin combines with the lethal factor for cell entry) and are described as highly specific and purified. In the study the fully human MAb (now recognized at MAb 1303) was selected after neutralizing the anthrax toxin in transgenic mice. MAb 1303 was then found to offer effective postsymptomatic treatment in rabbits exposed to aerosolized anthrax spores as well as serve as a protective agent in monkeys challenged with aerosolized anthrax spores following a single intramuscular injection.

"Selection of an anti-PA MAb by using a functional assay that is a surrogate for protection has resulted in the identification of a fully human MAb with potent activity in vivo and uncovered a previously unrecognized mechanism of antibody-mediated toxin neutralization that is important for currently used anthrax vaccines," say the researchers.

(L. Vitale, D. Blanset, I. Lowy, T. O'Neill, J. Goldstein, S.F. Little, G.P. Andrews, G. Dorough, R.K. Taylor, T. Keler. 2006. Prophylaxis and therapy of inhalational anthrax by a novel monoclonal antibody to protective antigen that mimics vaccine-induced immunity. Infection and Immunity, 74.10: 5840-5847.)

Adapted from materials provided by American Society For Microbiology.

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Postpartum Treatment Key For Depression; Prenatal Efforts Ineffective

Daily Science Journal (Oct. 18, 2007) — The key to preventing postpartum depression may be individual support provided after birth by a health professional and tailored to a mother's needs, says a University of Toronto researcher.

"Health professionals want to identify pregnant women who may be at risk for postpartum depression in hopes of initiating preventive strategies," says U of T nursing professor Cindy-Lee Dennis. "But in my review of studies from around the world, I found no preventive effect of any strategy initiated before birth, including prenatal classes specifically targeting postpartum depression. It's not because the interventions are theoretically weak, but it's because compliance is low -- women are busy and don't attend the classes."

After sifting through hundreds of studies, Dennis conducted a systematic review and meta-analysis of 15 randomized control trials focusing on prevention of postpartum depression. The trials involved 7,697 women. Her study is published in the July 2 issue of the British Medical Journal.

The evidence suggests postpartum depression may be preventable, says Dennis. In analyzing the prevention strategies used, Dennis found an overall 19 per cent reduction in postpartum depression. Individual assessment and intensive support provided by a health professional to at-risk women after they give birth was the most successful approach to preventing postpartum depression; group-based strategies weren't as effective. Risk factors for postpartum depression include past psychiatric history, a significant number of life stressors and lack of support.

"Individual, flexible postpartum care provided by a health professional and based on maternal need may have a preventive effect," Dennis says. "You must have a structured assessment within the first four weeks after birth with referrals to appropriate services that are accessible."

Dennis says her findings have implications for clinicians. "This systematic review tells us what type of strategy we can use to help prevent postpartum depression, when and how we should implement the strategy and with which clients," she says. "It's a nice summary of current research that health professionals can use as a tool when seeking to treat new mothers."

Adapted from materials provided by University Of Toronto, via EurekAlert!, a service of AAAS.

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