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Biomedical subjects

J G Huang

Publications and source records attributed to J G Huang.

7 recordsLinked to original sources
PubMed2006

Fresnel diffraction and fractal patterns from polygonal apertures.

Two compact analytical descriptions of Fresnel diffraction patterns from polygonal apertures under uniform illumination are detailed. In particular, a simple expression for the diffracted field from constituent edges is derived. These results have fundamental importance as well as specific applications, and they promise new physical insights into diffraction-related phenomena. The usefulness of the formulations is illuminated in the context of a virtual source theory that accounts for two transverse dimensions. This application permits calculation of fractal unstable-resonator modes of arbitrary order and unprecedented accuracy.

Journal Article↗
PubMed2005

Spontaneous optical fractal pattern formation.

We report, for the first time, spontaneous nonlinear optical spatial fractals. The proposed generic mechanism employs intrinsic nonlinear dynamics both to generate an initial pattern seed and to fill out structure across decades of spatial scale. We demonstrate this in one of the simplest of nonlinear optical systems, composed of a Kerr slice and a single-feedback mirror. In this case, the smallest pattern scales are limited by either the optical wavelength or the diffusion length of the medium photoexcitation. The dimension characteristics of these particular fractals are also derived.

Journal Article↗
PubMed1996

Sequence differences between human muscle and liver cDNAs for UDPglucose pyrophosphorylase and kinetic properties of the recombinant enzymes expressed in Escherichia coli.

UDP-Glc pyrophosphorylase (EC 2.7.7.9) catalyses the interconversion of MgUTP plus Glc1P and UDP-Glc plus MgPPi. Complementation of an Escherichia coli strain lacking this activity has allowed isolation of cDNA encoding this enzyme from a human muscle library. Two forms were identified and the nucleotide sequence of each was determined; they were found to differ only in the 5' region and we suggest that these arise from the use of a different first exon in the two transcripts. These nucleotide sequences are different from that of the cDNA which was isolated previously from a human liver library [Peng, H.-L. & Chang, H.-Y. (1993) FEBS Lett. 329, 153-158] and it is proposed that these liver and muscle forms are derived from different genes. The cDNA for muscle form I, muscle form II, the liver form, and the liver form fused to part of the lacZ gene were expressed in Escherichia coli and the kinetic properties of each enzyme were characterised. Muscle form I and the LacZ/liver fusion enzyme exhibit Michaelis-Menten kinetics towards all substrates while muscle form II has a sigmoidal dependence of rate upon the concentration of MgPPi. The liver form shows Michaelis-Menten kinetics towards MgUTP. For the remaining three substrates, complex kinetics were observed involving a combination of sigmoidicity at low substrate concentration and partial inhibition at high substrate concentration.

Amino Acid Sequence↗
PubMed1991

[Photodynamic therapy for genitourinary carcinomas--report of 26 tumors in 17 patients].

Twenty-six genito-urinary carcinomas in 17 patients were treated with photodynamic therapy (PDT). The complete response rate was 88.5%, significant response rate 7.7% and mild response rate 3.8%. Three tumors recurred (including 1 cancer in situ) during 9-23 months follow-up. Ultrastructurally, it was found that the necrosis of the malignant cells developed gradually and mitochondria was the major target of injury. No deleterious side effect was found.

Adult↗
PubMed1991

[Hyperbaric oxygen treatment for cystoid macular edema secondary to retinal vein occlusion].

A prospective study was made to estimate the effect of hyperbaric oxygen (HBO) on 14 eyes of cystoid macular edema (CME) secondary to retinal vein occlusion. The visual acuity was improved 2-6 lines (average 3.6 lines) after the treatment, while the control group of 12 cases showed little improvement. The therapeutic effect was stable, however, fluorescein angiography showed no leakage reduction from the perifoveal capillaries, or visual function was enhanced prior to eventual improvement in the fundus. Since HBO therapy has few contraindications nor side effects, it is an effective modality in the treatment of CME.

Aged↗