..."Described in a forthcoming issue of Physical Review Letters,* this demonstration of radio-frequency (RF) cooling of a relatively large object may offer a new tool for exploring the elusive boundary where the familiar rules of the everyday, macroscale world give way to the bizarre quantum behavior seen in the smallest particles of matter and light. "...

..." Because of the high atmospheric and free-space path losses of terahertz radiation, communications systems will require high-directivity antennas. However, in practical applications, direct beam paths are often blocked by people or objects, creating the need for beam redirection via a mirror.To optimize its function, a terahertz mirror should be highly reflective within a system’s frequency range for a wide range of incident angles, according to researchers at Technische Universität Braunschweig in Germany and at Rice University in Houston, who have developed such a device. The mirror, when strategically placed on walls inside a room, reflects beams from a terahertz transmitter. This allows for the signal to reach previously blocked areas. The mirrors developed by the team consist of four 63-μm-thick layers of high-resistivity silicon sandwiched between five 150-μm-thick layers of polypropylene. While silicon reduces the physical flexibility of the mirror, the researchers believe that polymer layers with enhanced refractive indices will solve this problem. Using a fiber-coupled terahertz time-domain spectrometer, the researchers measured transmission and reflection spectra for both s- and p-polarized waves. For normal incidence and a frequency range from 0.247 to 0.388 THz, the mirror reflected at least 95 percent of the incident power. The resulting 5 percent loss of radiation is far lower than that of most common building materials and, therefore, beneficial for communications. As the angle of incidence increases, the frequency range of high reflectivity, called a reflection band, experiences a blueshift. If the width of the reflection band is sufficiently large compared with the magnitude of the blueshift, a band can be identified for both polarizations in which the mirror is highly reflective for all incident angles. The researchers have found this omnidirectional band to be between 0.319 and 0.375 THz, thus demonstrating the ability of the mirror to improve terahertz communications systems."

"The persistant, day-after-day formation of clouds and thunderstorms over the tropics has a surprisingly big effect on the Earth's ionosphere some 200 miles above the cloud layer, according to new results from two of NASA's satellites published recently by physicists at the University of California, Berkeley. Data from NASA's Imager for Magnetopause to Aurora Global Exploration (IMAGE) satellite show that two parallel bands of ionized particles that encircle the Earth in the tropics are altered by persistent storms over the Amazon Basin in South America, the Congo Basin in Africa, and Indonesia. The net effect of these repeated storms is to create a denser region of ionospheric plasma over these areas that glows more brightly in ultraviolet light than does the rest of the two plasma bands. "This discovery will help improve forecasts of turbulence in the ionosphere, which can disrupt radio transmissions and the reception of signals from the Global Positioning System," said Thomas Immel, an assistant research physicist at UC Berkeley's Space Sciences Laboratory and lead author of a paper on the research published Aug. 11 in Geophysical Research Letters."...""The single pair of bright zones over the Pacific Ocean that is not associated with strong thunderstorm activity shows the disruption is propagating around the Earth, making this the first global effect on space weather from surface weather that's been identified," said Immel. "We now know that accurate predictions of ionospheric disturbances have to incorporate this effect from tropical weather." "This discovery has immediate implications for space weather, identifying four sectors on the Earth where space storms may produce greater ionospheric disturbances. North America is in one of these sectors, which may help explain why the U.S. suffers uniquely extreme ionospheric conditions during space weather events," he added."..

..."..scientists at the University of St. Andrews in the UK have demonstrated a potential solution, using a dielectric resonator and a prism coupler to create Fabry-Perot-like cavity modes that increase the force exerted by evanescent waves."..."Specifically, he suggested that an optimized design could boost the enhancement a thousandfold or more. With that, the technique would be suitable for such applications as cell sorting, driving lab-on-a-chip devices without the need for microfluidic control.".."To generate evanescent waves, they used an ytterbium-doped fiber laser operating at 1064 nm. The angle of incidence of the beam to the internally reflective surface of the prism was approximately 60°, the critical angle calculated to induce resonance. They filled the solution with monodispersed 5-μm-diameter polystyrene spheres and found that the force exerted at the critical angle was 10 times that exerted without the resonator. Using two counterpropagating waves, the researchers trapped 500-nm-diameter particles and found that they formed a linear array. According to Reece, the exact arrangement was unexpected. "(Applied Physics Letters, May 29, 2006, 221116. ) "

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