Search

Our recent study of the performance of integrating spheres shows prominent UV induced fluorescence features that are associated with contamination of the diffusing wall material by hydrocarbons. Because of multiple reflections of the radiation inside the integrating sphere, fluorescence is induced multiple times with each reflection of the incident radiation by the wall. Here, we report a simple theory on the fluorescence of integrating spheres developed from first principles. The results indicate a strong dependence of fluorescence on the reflectance of the diffusing material at both the excitation and fluorescence wavelengths as well as the geometry of the integrating sphere. Because of multiple reflection of the exciting radiation, a gain of more than an order of magnitude in fluorescence is possible compared with direct and single irradiation of a flat piece of the diffusing/fluorescing material. Applications of such fluorescence analysis for integrating spheres are discussed. OCIS codes: 120.3150, 120.5630, 300.6280.

We have studied the performance of polytetrafluoroethylene integrating spheres in the ultraviolet (UV) region with wavelengths as short as 200 nm. Two techniques were used for this study; first, the spectral throughput of an integrating sphere irradiated by a deuterium lamp was analyzed by a monochromator. Second, a UV laser beam was directed into an integrating sphere, and spectrally dispersed laser induced fluorescence was studied. Significant absorption and fluorescence features were observed in the UV region and attributed to the contamination in the integrating sphere. We demonstrate that integrating spheres are easily contaminated by environmental pollutants such as polycyclic aromatic hydrocarbons emitted from engine exhaust. Baking of the contaminated integrating sphere can reverse some but not all of the effects caused by contaminants. The implications for using integrating spheres for UV measurement are discussed. OCIS codes: 120.3150, 140.3610, 300.2530, 120.5630.

A new facility for measuring irradiance in the UV was commissioned recently at the National Institute of Standards and Technology (NIST). The facility uses the calculable radiation from the Synchrotron Ultraviolet Radiation Facility as the primary standard. To measure the irradiance from a source under test, an integrating sphere spectrometer--detector system measures both the source under test and the synchrotron radiation sequentially, and the irradiance from the source under test can be determined. In particular, we discuss the calibration of deuterium lamps using this facility from 200 to 400 nm. This facility improves the current NIST UV irradiance scale to a relative measurement uncertainty of 1.2% (k = 2). OCIS codes: 120.5630, 120.4800, 260.7190.

A comparative analysis of contents of advertisements in women's magazines of the United States and East Asia is presented. The analysis shows that women's beauty is considered as 'physical beauty of body' in the United States where as beauty is considered as 'beautiful face' in Asian advertisements.

We have measured the stability of a variety of photodiodes exposed to 157-nm light from a pulsed excimer laser by using a radiometry beamline at the Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology. The intense, pulsed laser light exposed the photodiodes, whereas the low-intensity, continuously tunable light from the synchrotron source measured changes in the characteristics of the photodiodes, such as in the responsivity and the reflectance from the surface of a photodiode. Photodiodes studied include both silicon pn-junction and Schottky-barrier types. Among these photodiodes, we found that the damage mechanism for photodiodes with Si[O.sub.2]-based passivating layers is mainly the buildup of Si[O.sub.O]-Si interface trap states. The interface trap state buildup is well known for other semiconductor devices and is generally recognized as a product induced by radiation with an energy more than the 9-eV Si[O.sub.2] bandgap energy rather than the 7.9-eV energy of the 157-nm radiation. Based on the generation of interface trap states, a model is proposed to describe the dependence of detector responsivity on exposure to 157-nm radiation. We also observed slow recovery in some of the damaged photodiodes, confirming that some of the interface trap states are only semipermanent. Radiation damage induced by low-power continuous 157-nm synchrotron light was also studied. As for the other photodiodes with no Si[O.sub.2] layers, measurement results support the assumption that the changes in responsivity are due mainly to the deposition of thin layers on the tops of the detectors during laser irradiation. OCIS codes: 040.6040, 040.7190, 120.5630, 140.2180.

Over the past 30 years, the literature on how women are depicted in advertising has been strongly influenced by studies conducted in the U.S. and Europe and may not fully describe the ways in which women are depicted in advertising across cultures. In this study we analyzed advertisements collected from women's fashion and beauty magazines in Singapore, Taiwan, and the United States to compare the ways in which Western and Asian models were portrayed in print advertisements. We found that although demure dress was used most often for both races, Western models were shown more frequently than Asian models in seductive dress. Western models were also posed more often than Asian models as the Seductive beauty type. Product categories also differed. Asian models were used more frequently in advertisements for hair and skin beauty products, whereas Western models dominated the clothing category. The findings suggest that Western models are used more than Asian models in advertisements which are 'body' oriented, and that Western models are used in advertisements in Asia when the underlying marketing strategy is that 'sex sells.' KEY WORDS: advertising; women; gender; beauty; Asia.

We have constructed and characterized a simple probe that is suitable for accurate measurements of irradiance in the UV to the vacuum UV spectral range. The irradiance meter consists of a PtSi detector located behind a 5-mm-diameter aperture. The probe was characterized at various wavelengths ranging from 130 to 320 nm by use of continuously tunable synchrotron radiation from the Synchrotron Ultraviolet Radiation Facility III. We determined the irradiance responsivity by scanning a small monochromatic beam over the active area of the irradiance meter and measuring its response on a grid with regular spacing. The angular response was also determined and shown to be suitable for applications such as photolithography. In addition, we studied the radiation damage using a 157-nm excimer laser and found that the irradiance meter can endure more than 100 J/[cm.sup.2] of 157-nm radiation before a noticeable change occurs in its responsivity. Many industrial applications such as UV curing, photolithography, or semiconductor chip fabrication that require accurate measurement of the irradiance would benefit from having such a stable, accurate UV irradiance meter. OCIS codes: 120.5630, 120.0280, 040.6070, 040.7190.

The behavior of the profit functions per unit time is considered when selling rate relies on current stock level.

Byline: Shenn-Yu Chao (1), Ping-Tung Shaw (2) Keywords: Fission; vortices; heton; Arctic Abstract: Close interactions among vertically stacked pairs of counter-rotating eddies under sea ice were investigated in numerical experiments. The numerical model contains a stratified ocean capped by an ice layer. Under the ice layer, a shallow brine source produces a top cyclone and a submerged anticyclone, while a shallow freshening source generates a top anticyclone and a submerged cyclone. Ice-exerted friction would dissipate the top eddy, leaving the submerged one in lone existence. In this work the winning vorticity is sought from group settings. Arrays of equally spaced salinity sources and sinks, alternate in sign but equal in strength, are employed to produce rows of vertically stacked eddy pairs. Fission occurs when adjacent vortex centers are separated by less than one Rossby radius. This process ejects parcels of density anomalies to the ambient ocean in upper depths. Low salinity anomalies are quickly dispersed into a thin surface layer and are unable to regenerate submerged eddies. High salinity parcels, being difficult to disperse, often maintain or regenerate submerged anticyclones below. Fission is particularly effective if a single row of salinity forcing is used. With multiple rows, fission is active only in the outer rows. The strong interaction among closely packed eddies operates in time scales of tens of days, helping explain the predominance of submerged anticyclones under Arctic sea ice. Author Affiliation: (1) Horn Point Laboratory, University of Maryland Center for Environmental Science, Cambridge, Maryland, 21613-0775, U.S.A (2) Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina, 27695-8208, U.S.A Article History: Registration Date: 01/10/2004

Circulation of water in the deep basin of the South China Sea is studied in a three-dimensional, climatology-driven circulation model, using a passive tracer. Two deep upwelling regions southwest of Taiwan and near Vietnam account for the deep water renewal. The region southwest of Taiwan is associated with the inflow of water at the sill depth of the Luzon Strait. Upwelling near Vietnam originates as a result of currents over the continental margin, beginning in August near 16 degree N, 114 degree E, and lasting until December with southwestern expansion.

A three-dimensional, primitive-equation model simulations of monthly surface circulation in South China Sea reveal the presence of a strong coastal jet at the western boundary and a southward current along the continental margin from China to southern Vietnam in winter. A northward current is observed in summer and a southward undercurrent formed during September reaches the surface in a month. The Kuroshio water is transferred westward by inflow through the Luzon Strait from October to February and the eastward flow in the Luzon Strait during summer transfers surface water west of Luzon. A pressure-driven subsurface current established by monsoon winds is present over the Sunda Shelf.

A cryogenic radiometer-based system was constructed at the National Institute of Standards and Technology for absolute radiometrie measurements to improve detector spectral power responsivity scales in the wavelength range from […]