Small Zeros of Additive Forms in Algebraic Number Fields

1991 Mathematics Subject Classification 11H50.     

Basicities of thiazole heterocyclic compounds and the reaction of 3-methyl-2-methylimino-Δ4-thiazolines with ethyl bromoacetate and 2-bromoacetophenone

The pK_a′s of several thiazole heterocyclic compounds have been determined and represent products with significantly high values. Because of their high basicities, sometimes these compounds were able to act as not only nucleophiles but also strong organic bases. 4-Substituted-3-methyl-2-methylimino-Δ⁴-thiazolines 5a-d reacted with ethyl bromoacetate in refluxing benzene, giving the corresponding N-alkylated salts 8a-d , while the products obtained from the reaction with 2-bromoacetophenone in the presence of base were pyrrolothiazines 10b-d.     

Printed compact dual band antenna for 2.4 and 5 GHz ISM band applications

A printed compact dipole antenna for dual ISM band (2.44 and 5 GHz) is presented. The proposed antenna fed by using a 50 /spl Omega/ coaxial line occupies a volume of 15/spl times/40/spl times/1 mm/sup 3/ (FR-4, permittivity 4.6). The impedance bandwidth for 10 dB return loss is about 400 MHz (from 2170 to 2570 MHz) at 2.4 GHz band and over 2300 MHz (from 4690 to beyond 7000 MHz) at 5 GHz band. The measured radiation gains range from 1.20 to 1.41 dBi at 2.4 GHz band and from 2.25 to 3.44 dBi at 5 GHz band, respectively.     

Synthesis and photoluminescence study of benz[f]indene derivatives

The synthesis and optical properties of a series of benz[f]indenes as new building blocks for electronic and optoelectronic materials are described.     

Acquisition of PN code with adaptive threshold for DS/SScommunications

An adaptive acquisition scheme of PN sequences is presented for DS/SS communications. The basic idea of the scheme is to apply the radar CFAR technique to the acquisition of PN sequences. The detection performance is analysed and an example of adaptive thresholding for multipath Rayleigh fading channels is given     

Integrated-Optic Polarization Controlling Devices Using Electro-Optic Polymers

Integrated-optic polarization controlling devices such as polarizers, polarization splitters, and polarization converters, are proposed and demonstrated in nonlinear optic polymers. Poling-induced birefringence in electro-optic polymers is exploited to fabricate the devices. The polymeric waveguide polarizers show low excess losses, and extinction ratios of 20.7 dB and 17.1 dB for TM-pass and TE-pass polarizers, respectively. The polymeric waveguide polarization splitters exhibit TE-TM mode splittings with crosstalk of 14.2 dB and 10.1 dB for TM and TE mode splittings, respectively. The polymeric waveguide polarization converters show successful TE/TM polarization mode conversion with conversion efficiencies of higher than 30 dB. The device employs poling-induced waveguides which have slowly rotating azimuth angle of optic axis along the light propagation direction. The novel polarization converter is insensitive to wavelength and easier to fabricate than the other polarization converters containing periodic structures.     

Scattering from a finite length rod with endpoint contribution

A uniform, high frequency analysis for calculating scattering from thin, finite length cylinders is presented. The cylinder diameter is assumed to be small (on the order of a wavelength or less) so that the modal solution is valid. The total field consists of the incident field, the scattered field from the specular point, and two endpoint contributions. A thin wire tip diffraction coefficient (TDC) is developed for calculating the end point contributions. The incident fields are those of a spherical source radiating throughout space. While the specularly scattered field and end point contributions are discontinuous, these discontinuities cancel each other, resulting in a uniformly continuous total field. Good agreement is obtained between measured and calculated results.     

Topical Application of Photofrin® for Oral Neoplasms in Animal

Early diagnosis improves oral cancer prognosis. Exact demarcation of tumor margins improves surgical outcomes. This study evaluates Photofrin^® fluorescence: a new diagnostic procedure for detection of oral neoplasms in animal models. Fourteen male Golden Syrian hamsters were used. 0.5% D.M.B.A (9,10 dimethyl1-1,2-benzanethracene) was brushed onto cheek pouches bilaterally daily for 2,weeks. Hamsters with oral neoplasms received 2.5,mg/ml Photofrin^® solution topically. After 3h the neoplasms underwent fluorescence illumination (λex=380–420,nm). A quantitative analysis of the fluorescence contrast between the neoplastic and surrounding tissue was performed using the RGB Mode and the Gray Scale. (GS) Statistical analysis was performed using the ANOVA test. Analysis of the 14 hamsters’ 28 biopsies revealed 4 (14.3%) displayed squamous hyperplasia (1 mild, 3 severe) and 24 (85.7%) displayed squamous cell carcinoma. The sensitivity of neoplasms evaluated using the RGB and GS modes combined resulted in 92.15% (in vivo macroscopic image) and 93.45% (histological). The specificity of neoplasms evaluated via RGB and GS modes combined resulted in 94.78% (in vivo macroscopic image) and 97.30% (histological). The difference between healthy tissue and the lesions as a group is statistically significant. Photofrin^® fluorescence provides a sensitive, non-invasive technique for early identification of malignant neoplasms in the oral cavities of animal models.     

Improvements of spreading codes utilisation efficiency forintegrated multimedia services in CDMA network

A wireless MAC protocol for the CDMA network is proposed which provides the various bit rates required to support the integrated multimedia services. The proposed method improves the spreading codes utilisation efficiency by sharing limited spreading codes among all mobile terminals