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Number 431, June 2, 1999 by Phillip F. Schewe and Ben Stein
THIRD HARMONIC MICROSCOPE. Imaging biological samples often involves telling apart one wet thing from another. A relatively new way of gaining the needed contrast is to exploit the nonlinear optical features of the sample itself by using a process in which a high-power laser beam can, when it is brought to a tight focus in certain media, generate subsidiary light waves at twice the original frequency (second harmonic), three times the frequency (third harmonic), and so on. If the detector is sensitive to just the third harmonic radiation, say, then by scanning the laser focus across the face of the sample, an image can be built up with a spatial resolution as small as the focal size. Jeff Squier at UC San Diego (619-534-0290, jsquier@chem.ucsd.edu and his colleagues have used this scheme to produce the first 3-dimensional third-harmonic image of a living system. (Paper JTuA2, May 25, at the electro-optics and quantum electronics meeting in Baltimore; see figure at www.aip.org/png/html/thirdharm.html.)
METHANE DWARFS is the name for a new type of celestial object. Actually they are a subclass of brown dwarf. With a mass of less than 80 times that of Jupiter, Brown dwarfs cannot sustain the fusion reactions that burn in our sun. At this week's meeting in Chicago of the American Astronomical Society, Zlatan Tsvetanov and Wei Zheng of Johns Hopkins University reported seeing several very red objects very like one observed (Gliese 229B) in 1995. The new objects, glimpsed with the Sloan Digital Sky Survey telescope, are red not because their spectrum has been red shifted owing to great distance, but because they are nearby and very cool. In fact they are cool enough to permit the presence of methane, which normally dissociates amid the heat of stars and even in other, warmer, brown dwarfs. (Fermilab press release, 31 May; www.aas.org/meetings/aas194/program/index.html)
PH.D. PHYSICISTS IN THE U.S. REPORTED A MEDIAN SALARY OF $70,000 in 1998, an increase of 8 percent over the past two years, and salary gaps appear to be narrowing between physicists with master's ($57,000) and bachelor's degrees ($54,000). This information comes from approximately 9,250 respondents to an American Institute of Physics survey of members belonging to its ten member societies. Moreover, the unemployment rate of the respondents is 0.7%, the lowest this decade. However, physics master's recipients who teach at high schools reported only a 3 percent increase in their salary, not keeping up with the pace of inflation. The highest median salary belongs to those in the healthcare industry ($87,500). Although median salaries differed across employment sectors for respondents in their early- and mid-career, those working in many sectors reach a median salary of $90,000-100,000 after 25 years of experience, especially when one considers supplemental income, such as consulting and summer teaching often done by physicists with 9-10 month contracts at colleges and universities. ("1998 Salaries: Society Membership Survey," issued in April by the AIP Education and Employment Statistics Division; to order single copies, and for further information, please contact Amanda Benedict, abenedic@aip.org, 301-209-3388)
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