A New Reflection in the Mirror

scanning electron microscope image of some of the magnetic mirror's “fish scale”-shaped aluminum nanowires. Credit: Alexander Schwanecke

A research group has devised a new type of mirror that reverses the magnetic field of a light wave upon reflection, rather than its electric field, as regular mirrors do. Seems like a minor difference? It's not.

“Our mirror's ability to reverse the magnetic field of a light wave but not its electric field is extremely unusual,” physicist Alexander Schwanecke, the study's corresponding scientist, said to PhysOrg.com. Schwanecke is a researcher at the NanoPhotonics Portfolio Centre at the University of Southampton in the United Kingdom. “It is the first demonstration of an entirely new type of optical tool.”
A typical household mirror works like this: Photons (particles of light) bounce off an object or person, hit the mirror, and are absorbed by electrons on the surface of its metal backing. The electrons almost instantly emit “reflected” photons (not the same photons that came in, as those are absorbed and gone), which travel to our eyes, allowing us to see our image. Photons that strike the mirror head-on are reflected squarely back, and those hitting at an angle are reflected at the same angle in the other direction, forming a V-shaped path. This is the law of reflection.
To understand the work by Schwanecke and his colleagues, however, we must remember that light is both a particle and a wave, and that, as a wave, it consists of an electric-field component and a magnetic-field component. After a reflection, the direction of the emitted light wave's electric field is reversed (this is one type of a “phase change”) but the magnetic component is not.
This magnetic mirror produces the opposite scenario: a flipped magnetic field and an unchanged electric field. The mirror has three layers: a layer of aluminum, a layer of silicon dioxide, and finally a layer of carefully arranged aluminum nanowires, shaped into a wavy pattern that the researchers call “fish scales.” The fish-scale shape is important because it allows the light to interact with the nanowires in a particular way, due to the spacing between each “scale.” As a result, the scales resonate with the light much like molecules would.
The mirror is tiny and square, about 500 micrometers (millionths of a meter) on each side, and contains about one million fish-scale-shaped elements. It works best for visible light, but the group expects that, with some tweaks to the fish-scale pattern, near-infrared light would work, too.

The nanowire layer is the key to the mirror's function. The curved nanowire “fish scales,” like molecules, have dimensions that are smaller than the wavelength of visible light. This means that they can interact with the light to influence or directly produce the material's overall optical response, in this case, a reversal of the light's magnetic field.
The researchers discovered the mirror's ability by observing a reflection using an interferometer, a device that can detect the difference in behavior of two light waves by recording what happens when they “interfere,” or cross paths.
“One characteristic of our mirror is that it is very sensitive to energy losses at the surface,” said Schwanecke. “This property could make it very useful for improving devices that work by detecting light, such as photodetectors.”
The mirror could also be useful, he says, in the detection of tiny particles or molecules near the mirror’s surface. If a particle or molecule was nearby and emitted a photon, the mirror would reflect the photon’s electric component without reversing it. A “normal” mirror would reverse it, thus weakening the signal and making it harder to detect the photon and, by extension, the particle or molecule.
The mirror’s potential to work with near-infrared light (light close to the visible range but still in the infrared) could make it advantageous to the telecommunications industry, in which near-infrared light is commonly used.

(c) www.physorg.com

What’s Making Us Sick Is an Epidemic of Diagnoses

by H. Gilbert Welch, Lisa Schwartz and Steven Woloshin

For most Americans, the biggest health threat is not avian flu, West Nile or mad cow disease. It’s our health-care system.

You might think this is because doctors make mistakes (we do make mistakes). But you can’t be a victim of medical error if you are not in the system. The larger threat posed by American medicine is that more and more of us are being drawn into the system not because of an epidemic of disease, but because of an epidemic of diagnoses. 
                                                                                                              Harry Campbell

Americans live longer than ever, yet more of us are told we are sick.

How can this be? One reason is that we devote more resources to medical care than any other country. Some of this investment is productive, curing disease and alleviating suffering. But it also leads to more diagnoses, a trend that has become an epidemic.

This epidemic is a threat to your health. It has two distinct sources. One is the medicalization of everyday life. Most of us experience physical or emotional sensations we don’t like, and in the past, this was considered a part of life. Increasingly, however, such sensations are considered symptoms of disease. Everyday experiences like insomnia, sadness, twitchy legs and impaired sex drive now become diagnoses: sleep disorder, depression, restless leg syndrome and sexual dysfunction.

Perhaps most worrisome is the medicalization of childhood. If children cough after exercising, they have asthma; if they have trouble reading, they are dyslexic; if they are unhappy, they are depressed; and if they alternate between unhappiness and liveliness, they have bipolar disorder. While these diagnoses may benefit the few with severe symptoms, one has to wonder about the effect on the many whose symptoms are mild, intermittent or transient.

The other source is the drive to find disease early. While diagnoses used to be reserved for serious illness, we now diagnose illness in people who have no symptoms at all, those with so-called predisease or those “at risk.”

Two developments accelerate this process. First, advanced technology allows doctors to look really hard for things to be wrong. We can detect trace molecules in the blood. We can direct fiber-optic devices into every orifice. And CT scans, ultrasounds, M.R.I. and PET scans let doctors define subtle structural defects deep inside the body. These technologies make it possible to give a diagnosis to just about everybody: arthritis in people without joint pain, stomach damage in people without heartburn and prostate cancer in over a million people who, but for testing, would have lived as long without being a cancer patient.

Second, the rules are changing. Expert panels constantly expand what constitutes disease: thresholds for diagnosing diabetes, hypertension, osteoporosis and obesity have all fallen in the last few years. The criterion for normal cholesterol has dropped multiple times. With these changes, disease can now be diagnosed in more than half the population.

Most of us assume that all this additional diagnosis can only be beneficial. And some of it is. But at the extreme, the logic of early detection is absurd. If more than half of us are sick, what does it mean to be normal? Many more of us harbor “pre-disease” than will ever get disease, and all of us are “at risk.” The medicalization of everyday life is no less problematic. Exactly what are we doing to our children when 40 percent of summer campers are on one or more chronic prescription medications?

No one should take the process of making people into patients lightly. There are real drawbacks. Simply labeling people as diseased can make them feel anxious and vulnerable — a particular concern in children.

But the real problem with the epidemic of diagnoses is that it leads to an epidemic of treatments. Not all treatments have important benefits, but almost all can have harms. Sometimes the harms are known, but often the harms of new therapies take years to emerge — after many have been exposed. For the severely ill, these harms generally pale relative to the potential benefits. But for those experiencing mild symptoms, the harms become much more relevant. And for the many labeled as having predisease or as being “at risk” but destined to remain healthy, treatment can only cause harm.

The epidemic of diagnoses has many causes. More diagnoses mean more money for drug manufacturers, hospitals, physicians and disease advocacy groups. Researchers, and even the disease-based organization of the National Institutes of Health, secure their stature (and financing) by promoting the detection of “their” disease. Medico-legal concerns also drive the epidemic. While failing to make a diagnosis can result in lawsuits, there are no corresponding penalties for overdiagnosis. Thus, the path of least resistance for clinicians is to diagnose liberally — even when we wonder if doing so really helps our patients.

As more of us are being told we are sick, fewer of us are being told we are well. People need to think hard about the benefits and risks of increased diagnosis: the fundamental question they face is whether or not to become a patient. And doctors need to remember the value of reassuring people that they are not sick. Perhaps someone should start monitoring a new health metric: the proportion of the population not requiring medical care. And the National Institutes of Health could propose a new goal for medical researchers: reduce the need for medical services, not increase it.

Dr. Welch is the author of “Should I Be Tested for Cancer? Maybe Not and Here’s Why” (University of California Press). Dr. Schwartz and Dr. Woloshin are senior research associates at the VA Outcomes Group in White River Junction, Vt.

(c) www.nytimes.com

Super Slurper: From Laboratory Bench To Library Shelf

Science Daily — Super Slurper, a cornstarch-based superabsorbent polymer invented by Agricultural Research Service (ARS) scientists over 30 years ago, continues to fan the entrepreneurial spirit.

A flake of Super Slurper absorbs nearly 2,000 times its own weight in moisture. (Photo by George Robinson)

Take, for example, Nicholas Yeager, president of Artifex Equipment, Inc., a Penngrove, Calif., company specializing in book and document restoration. This fall, Yeager's company began mass-producing Zorbix, a sheetlike product based on Super Slurper that can dry out waterlogged library materials before destructive molds take hold.

Zorbix's commercialization is the latest chapter in a storied history of Super Slurper spinoffs that followed an ARS patent on the starch polymer in 1976. Among those spinoffs were disposable diapers, wound dressings, fuel filters and seed coatings.

The Zorbix story began in 2003, when Yeager was contacted by Kate Hayes, an information specialist with the Technology Transfer Information Center at the ARS National Agricultural Library in Beltsville, Md. Hayes, now retired, proposed using Super Slurper as a fast, new way of drying books exposed to flooding, leaky pipes and other watery disasters.

Intrigued, Yeager ran a simple test: He pressed Super Slurper onto the pages of a paperback novel that he had wetted. Yeager informed Hayes that her idea had worked, and that he wanted to explore the polymer's potential further.

In August 2003, NAL and Artifex entered into a material-transfer cooperative research and development agreement to both expedite and formalize Hayes and Yeager's bicoastal collaboration. In February 2004, the U.S. Department of Agriculture (USDA) also awarded a Small Business Innovation Research grant to Artifex.

In studies there, Yeager changed Super Slurper's flake form into another that allowed the creation of thin, flexible sheets, which he named Zorbix. In his tests and independent studies, the sheets worked as well as or better than other drying methods, including vacuum drying, poultices and blotters.

To better meet demand since debuting Zorbix in March, Artifex has obtained automated equipment capable of making thousands of the sheets per hour.

ARS is USDA's chief scientific research agency.

(c) www.sciencedaily.com

X-ray Evidence Supports Possible New Class Of Supernova

Science Daily — Recent observations have uncovered evidence that helps to confirm the identification of the remains of one of the earliest stellar explosions recorded by humans.

The combined image from the Chandra and XMM-Newton X-ray observatories of RCW 86 shows the expanding ring of debris that was created after a massive star in the Milky Way collapsed onto itself and exploded. (Chandra: NASA/CXC/Univ. of Utrecht/J.Vink et al. XMM-Newton: ESA/Univ. of Utrecht/J.Vink et al.)

The new study shows that the supernova remnant RCW 86 is much younger than previously thought. As such, the formation of the remnant appears to coincide with a supernova observed by Chinese astronomers in 185 A.D. The study used data from NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton Observatory,

"There have been previous suggestions that RCW 86 is the remains of the supernova from 185 A.D.," said Jacco Vink of University of Utrecht, the Netherlands, and lead author of the study. "These new X-ray data greatly strengthen the case."

When a massive star runs out of fuel, it collapses on itself, creating a supernova that can outshine an entire galaxy. The intense explosion hurls the outer layers of the star into space and produces powerful shock waves. The remains of the star and the material it encounters are heated to millions of degrees and can emit intense X-ray radiation for thousands of years.

In their stellar forensic work, Vink and colleagues studied the debris in RCW 86 to estimate when its progenitor star originally exploded. They calculated how quickly the shocked, or energized, shell is moving in RCW 86, by studying one part of the remnant. They combined this expansion velocity with the size of the remnant and a basic understanding of how supernovas expand to estimate the age of RCW 86.

"Our new calculations tell us the remnant is about 2,000 years old," said Aya Bamba, a coauthor from the Institute of Physical and Chemical Research (RIKEN), Japan. "Previously astronomers had estimated an age of 10,000 years."

The younger age for RCW 86 may explain an astronomical event observed almost 2000 years ago. In 185 AD, Chinese astronomers (and possibly the Romans) recorded the appearance of a new bright star. The Chinese noted that it sparkled like a star and did not appear to move in the sky, arguing against it being a comet. Also, the observers noticed that the star took about eight months to fade, consistent with modern observations of supernovas.

RCW 86 had previously been suggested as the remnant from the 185 AD event, based on the historical records of the object's position. However, uncertainties about the age provided significant doubt about the association.

"Before this work I had doubts myself about the link, but our study indicates that the age of RCW 86 matches that of the oldest known supernova explosion in recorded history," said Vink. "Astronomers are used to referencing results from 5 or 10 years ago, so it's remarkable that we can build upon work from nearly 2000 years ago."

The smaller age estimate for the remnant follows directly from a higher expansion velocity. By examining the energy distribution of the X-rays, a technique known as spectroscopy, the team found most of the X-ray emission was caused by high-energy electrons moving through a magnetic field. This is a well-known process that normally gives rise to low-energy radio emission. However, only very high shock velocities can accelerate the electrons to such high energies that X-ray radiation is emitted.

"The energies reached in this supernova remnant are extremely high," said Andrei Bykov, another team member from the Ioffe Institute, St. Peterburg, Russia. "In fact, the particle energies are greater than what can be achieved by the most modern particle accelerators."

The difference in age estimates for RCW 86 is due to differences in expansion velocities measured for the supernova remnant. The authors speculate that these variations arise because RCW 86 is expanding into an irregular bubble blown by a wind from the progenitor star before it exploded. In some directions, the shock wave has encountered a dense region outside the bubble and slowed down, whereas in other regions the shock remains inside the bubble and is still moving rapidly. These regions give the most accurate estimate of the age.

The study describing these results appeared in the September 1 issue of The Astrophysical Journal Letters. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory, Cambridge, Mass., controls science and flight operations from the Chandra X-ray Center, Cambridge, Mass. XMM-Newton is an European Space Agency science mission managed at the European Space Research and Technology Centre, Noordwijk, the Netherlands for the Directorate of the Scientific Programme.

(c) www.sciencedaily.com

Catching Cosmic Clues

by Joanne Baker

THE AUTHOR HENRY JAMES WROTE THAT "EXPERIENCE IS … A KIND OF HUGE spider-web of the finest silken threads suspended in the chamber of consciousness, and catching every airborne particle in its tissue." Particle astrophysicists are trying to weave their own webs by building vast detectors on Earth and in space that will ensnare cosmic particles and so teach us about the building blocks of the universe.

Thanks to enormous progress in cosmology in recent years, astrophysicists are both pleased and perplexed. On the one hand, they have succeeded in nailing down the universe's mass, geometry, and expansion rate. But on the other, they have discovered that 95% of the stuff of the universe is in two unknown forms that they have named "dark matter" and "dark energy." Only 5% is normal matter: electrons, protons, and neutrons. Pinning down the nature of this missing mass and energy is difficult, because dark matter does not absorb light or interact with normal atoms; the dark energy driving accelerated cosmic expansion is even more intangible. Particle physicists may, however, have the tools to test some ideas. In this special issue devoted to particle astrophysics, a rapidly developing interdisciplinary area, six Perspectives cover not only candidates for dark matter but also the physics of the Big Bang fireball, neutrinos, cosmic rays, and sources of extreme-energy gamma rays such as black holes.

Neutrino physics has leapt ahead in recent years, with measurements of neutrino mass and oscillations between different types, or flavors. The next frontier is neutrino astronomy, capturing neutrinos from sources more distant than the Sun, and vast arrays of detectors are being built under the ice in Antarctica and under the Mediterranean Sea to do this. Neutrinos hardly interact with normal matter at all, but occasionally they do and produce ghostly flashes of light that detectors can catch. If the universe's hidden mass takes the form of other particles, then axions and WIMPs (weakly interacting massive particles) are the prime suspects. Experiments, many hidden below ground to isolate the detectors from other stray particles, have been designed and are being implemented to spot these exotic particles via their recoil off other nuclei. Currently, these detectors are modest in size, but detectors now on the drawing board could weigh as much as a ton.

High-energy particles can also be used for astronomy. Cosmic-ray observatories are nearing the sensitivities required to detect individual sources in the sky, thus testing acceleration physics. Cosmic rays are created by extreme astrophysical sources such as supernova shock waves, gamma-ray bursts, and near black holes. Very-high-energy gamma-ray emission from these sources is already detectable with new telescope arrays and has constrained the physics of particle jets emanating from compact stars and black holes.

Particle astrophysics is an exciting area brimming with promise. As scientists come together to combine their know-how, maybe in the next decade we will find the missing matter, and crown the already remarkable achievements of cosmology.

(c) www.sciencemag.org

What Landed in New Jersey? It Came From Outer Space

by Kareem Fahim

It was not from the neighborhood.

The object that tore through the roof of a house in the New Jersey suburbs this week was an iron meteorite, perhaps billions of years old and maybe ripped from the belly of an asteroid, experts who examined it said yesterday.

Tentatively named “Freehold Township” for the place where it landed — and ruined a second-floor bathroom — the meteorite is only the second found in New Jersey, said Jeremy S. Delaney, a Rutgers University expert who examined it.

“It’s a pretty exciting find,” said Dr. Delaney, who has examined thousands of meteorites. He said that the first New Jersey meteorite was found in 1829, in the seaside town of Deal.

The meteorite now belongs to the family whose house it ended up in, said Lt. Robert Brightman of the Freehold Township Police Department, adding that they had asked not to be identified.

The family has not yet given permission for physical testing of the meteorite, but from looking at it, Dr. Delaney and other experts were able to tell that the object it had been part of — perhaps an asteroid — cooled relatively fast.

It is magnetic, and reasonably dense, they determined. The leading edge — the one that faced forward as it traveled through the earth’s atmosphere — was much smoother, while the so-called trailing edge seemed to have caught pieces of molten metal.

In fact, Mr. Delaney said, it seemed very similar to another meteorite fragment, the Ahnighito, now on display at the American Museum of Natural History.

“This little guy is a lot like it,” he said. “It’s a good candidate for the core of an asteroid.”

And the scientists are hoping that the owners of the “Freehold Township” will make it available for testing and public viewing, like the Ahnighito, a 34-ton chunk of the Cape York meteorite found in Greenland.

Or, they could sell it.

“The worth of a meteorite like this is almost completely determined by where it fell,” said Eric Twelker, a geologist and a dealer in meteorites, who buys and sells perhaps a hundred of them a month on meteoritemarket.com, his Web site. He was speaking of the premium placed on meteorites with a compelling back story, like the football-size rock that crashed into a parked Chevrolet in Peekskill, N.Y., in 1992.

(c) www.nytimes.com

Cancer-killing Invention Also Harvests Stem Cells

Science Daily — Associate Professor Michael King of the University of Rochester Biomedical Engineering Department has invented a device that filters the blood for cancer and stem cells.  When he captures cancer cells, he kills them.  When he captures stem cells, he harvests them for later use in tissue engineering, bone marrow transplants, and other applications that treat human disease and improve health.

Bone marrow cells that have been purified in a StemCapture device. (Image courtesy of School of Engineering and Applied Sciences, University of Rochester)

With Nichola Charles, Jared Kanofsky, and Jane L. Liesveld of the University of Rochester, King wrote about his discoveries in "Using Protein-Functionalized Microchannels for Stem Cell Separation," Paper No. ICNMM2006-96228, Proceedings of the ASME, June 2006.  King’s team includes scientists at StemCapture, Inc., a Rochester company that bought the University patent for King’s technique in November 2005 to build the cancer-killing and stem cell-harvesting devices.  The technique can be used in vivo, meaning a device is inserted in the body, or in vitro, in which case the device resides outside of the body – either way, the device kills cancer cells and captures stem cells, which grow into blood cells, bone, cartilage, and fat.

When King was working at the University of Pennsylvania from 1999 to 2001, one of his labmates discovered that bone marrow stem cells stick to adhesive proteins called selectins more strongly than other cells -- including blood cells -- stick to selectins.  When King came to the University of Rochester in early 2002, he started studying the adhesion of blood cells to the vascular wall, the inner lining of the blood vessels.  During inflammation, the vascular wall presents surface selectins that adhere specifically to white blood cells.  These selectins cause the white blood cells to roll slowly along the vascular wall, seeking signals that tell them to crawl out of the bloodstream.  This is how white blood cells migrate to bacterial infections and tissue injuries.  King set out to find a way to duplicate this natural process. 

First, he noted that the selectins form bonds with the white blood cells within fractions of a second, then immediately release the cells back into the bloodstream.  He also realized that selectin is the adhesive mechanism by which bone marrow stem cells leave the bloodstream and find their way back into bone marrow.  This is how bone marrow transplantation works.  Finally, he learned that when a cancer cell breaks free of a primary tumor and enters circulation, it flow through the bloodstream to a remote organ, then leaves the bloodstream and forms a secondary tumor.  This is how cancer spreads.  He put these facts together with one more, very important fact:  the selectins grab onto a specific carbohydrate on the surfaces of white blood cells, stem cells, and cancer cells.  Associate Professor King decided to capture stem and cancer cells before the selectins release them. 

Harvesting Stem Cells

Because bone marrow stem cells stick to selectin surfaces more strongly than other cells, King’s group coated a slender plastic tube with selectin.  They then did a series of lab experiments, both in vitro and in vivo using rats, with this selectin-coated tube to filter the bloodstream for stem cells.  It worked, and the King Lab discovered that they could attract a large number of cells to the wall of their selectin-coated device, and that 38% of these captured cells were stem cells.  King envisioned a system by which doctors could remove stem cells from the bloodstream by flowing the cells through a device, and make a more concentrated mixture containing, say, 20-40 percent stem cells.  These stem cells could then be used for tissue engineering or bone marrow transplantation. 

This is a non-controversial way of obtaining stem cells that can be differentiated into other, useful cells.

King’s team can capture significant amounts of cells of the lymphatic and circulatory systems, and potentially mesenchymal stem cells, which are unspecialized cells that form tissue, bone, and cartilage.  Current procedures enable the specific capture of hematopoietic stem cells, which grow (or differentiate) over time into all of the different blood cells, and the specific capture of stem cells that differentiate into bone marrow cells.  The device itself uses a combination of microfluidics, or fluid flow properties, and specialized selectin coatings. 

Killing Cancer Cells

Another exciting application of King’s invention is filtering the blood for cancer cells and triggering their death, an innovative, new method to prevent the spread of cancer.  When someone has a primary cancer tumor, a small number of cancer cells circulates through the bloodstream.  In a process called metastasis, these cells are transmitted from the primary tumor to other locations in the body, where they form secondary, cancerous growths. 

As a cancer cell flows along the implanted surface, King’s device captures it and delivers an apoptosis signal, a biochemical way of telling the cancer cell to kill itself.  Within two days, that cancer cell is dead.  Normal cells are left totally unharmed because the device selectively targets cancer cells. 

The apoptosis signal is delivered by a molecule called TRAIL that coats the cancer-killing device.  Cancer cells have five types of proteins that recognize and bind to TRAIL, but only two trigger cell death.  The other three are called decoy receptors.  Healthy cells contain a lot of decoy receptors, giving them a natural protection against TRAIL, whereas cancer cells mainly express the two receptors that signal cell death. 

During the death of the cancer cells, TRAIL is not depleted or used up in any way, and in fact, it stays active for many weeks or months.  The same TRAIL molecules can kill enormous numbers of cancer cells. 

A possible way to use the cancer-killing invention is to implant the device in the body before primary tumor surgery or chemotherapy.  When doctors remove a primary tumor, the procedure itself can release cancer cells into the bloodstream.  King’s device would grab those cancer cells and kill them, greatly reducing the possibility of metastasis.

Associate Professor King envisions that the device would use a shunt similar to the type used in hospitals today.  This shunt would reside on the exterior of the arm or be implanted beneath the skin.  Some of the blood flow would bypass the capillary bed and instead go into the shunt, which could remain implanted for many weeks, continually removing and killing cancer cells.  King’s first targets are colorectal cancer and blood malignancies such as leukemia.

Note: This story has been adapted from a news release issued by University of Rochester, School of Engineering and Applied Sciences.

(c) www.sciencedaily.com