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Biomedical subjects

D Quon

Publications and source records attributed to D Quon.

24 records · Page 2Linked to original sources
PubMed1986

Quantitative concepts in avoiding intraocular lens damage from the Nd:YAG laser in posterior capsulotomy.

Damage to the intraocular lens (IOL) in Nd:YAG laser posterior capsulotomy is a complication to be avoided. The damage threshold for many of the commercially available IOLs was determined. The power density at the focal point was calculated for FDA approved Nd:YAG lasers. Based on the therapeutic gap concept it is recommended that only power levels below the damage threshold be used in photodiscission posterior capsulotomy to minimize the risk of Nd:YAG laser IOL damage.

Cataract Extraction↗
PubMed1985

Perception of orientation of motion as affected by change in divergence of texture, change in size, and in velocity.

When there is relative motion between an observer and a textured surface such as the ground, motion-related visual information is available about the orientation of the surface through vergence of the paths of the elements of the texture, change in their sizes and in their velocities. This experiment determined the perceptual effectiveness of each variable in foveal and peripheral viewing for producing perceptions of three-dimensional motion. The three variables were electronically separated and displayed singly, in all possible pairs, and all together. Subjects communicated their perceptions of degree of perceived surface tilt at the top, bottom, and middle of the display for the eight different combinations of variables because, during pilot work perceived surface bendings were frequently noted where top, bottom, and middle appeared tilted to different extents. All three variables can lead to relatively reliable perceptions of perceived orientation of the plane of motion, with change in velocity being the most powerful determiner. Change in size was the weakest. Certain combinations can lead to perceptions of extreme warping and should be avoided in motion displays. Subjects consistently underestimate the amount of simulated tilt. Foveal viewing was more accurate than peripheral viewing but peripheral performance was adequately consistent as an input channel for some orientation tasks.

Depth Perception↗
PubMed1985

The inadvertent CT demonstration of intussusception.

We report a patient with idiopathic ceco-colic intussusception diagnosed by computed tomography (CT). Due to an unusual set of circumstances, the accepted algorithm of diagnostic investigations was not followed. This led to the inadvertent CT demonstration of an intussusception in an adult as a thick-walled mass containing a multiplicity of barium and gas-filled loops.

Adult↗
PubMed1979

The linkage arrangement of four rabbit beta-like globin genes.

Four different regions of rabbit beta-like globin gene sequences designated beta 1, beta 2, beta 3 and beta 4 were identified in a set of clones isolated from a bacteriophage lambda library of chromosomal DNA fragments (Maniatis et al., 1978). Restriction mapping and blot hybridization (Southern, 1975) studies indicate that a subset of these clones containing beta 1 and beta 2 hybridizes to an adult beta-globin cDNA clone (Maniatis et al., 1976) more efficiently than to a human gamma-globin cDNA clone (Wilson et al., 1978), while another subset containing beta 3 and beta 4 displays the converse hybridization specificity. beta 1 was identified as the adult beta-globin gene, while beta 2, beta 3 and beta 4 have not been identified with any known rabbit globin polypeptides. Cross-hybridization and transcriptional orientation experiments indicate that the set of beta-like gene clones contains overlapping restriction fragments encompassing 44 kb of rabbit chromosomal DNA. In addition, all four genes have the same transcriptional orientation and are arranged in the order 5'-beta 4-beta 3-beta 2-beta 1-3'.

Animals↗
PubMed1978

The isolation of structural genes from libraries of eucaryotic DNA.

We present a procedure for eucaryotic structural gene isolation which involves the construction and screening of cloned libraries of genomic DNA. Large random DNA fragments are joined to phage lambda vectors by using synthetic DNA linkers. The recombinant molecules are packaged into viable phage particles in vitro and amplified to establish a permanent library. We isolated structural genes together with their associated sequences from three libraries constructed from Drosophila, silkmoth and rabbit genomic DNA. In particular, we obtained a large number of phage recombinants bearing the chorion gene sequence from the silkmoth library and several independent clones of beta-globin genes from the rabbit library. Restriction mapping and hybridization studies reveal the presence of closely linked beta-globin genes.

Base Sequence↗