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D Weller

Publications and source records attributed to D Weller.

63 records · Page 4Linked to original sources
PubMed1988

Negative ion fast atom bombardment mass spectrometry of oligodeoxynucleotide carbamate analogs.

Oligonucleotide analogs, in which carbamate rather than phosphodiester linkages form the backbone, have been analyzed by negative ion fast atom bombardment mass spectrometry. These oligodeoxynucleotides, dimers (982.4 daltons) to 11-mers (4356.5 daltons), show intense [M - H]- ions and some degree of cleavage of the sugar-carbamate backbone structure in repeating fashion on both sides of the carbonyl groups. Sequencing of the shorter chain oligonucleotide analogs, up to six bases long, is demonstrated by complete 3' and 5' terminal sequence fragment ions. Longer chain oligomers show partial sequencing information.

Carbamates↗
PubMed1975

Requirement of low oxidation-reduction potential for photosynthesis in a blue-green alga (Phormidium sp.).

Photosynthesis in a Phormidium species which forms dense conical-shaped structures in thermal springs is strongly inhibited by aeration but is stimulated by sulfide and other agents (cysteine, thioglycolate, sulfite) which lower the oxidation-reduction potential. The compact structures which this alga forms in nature may restrict oxygen penetration from the enviroment so that the anaerobic or microaerophilic conditions necessary ofr photosynthesis can develop. The alga may be defective in a regulatory mechanism that controls the reoxidation of reduced pyridine nucleotides formed during photosynthesis. It is suggested that other mat-forming and benthic blue-green algae may also prefer anaerobib conditions for growth and photosynthesis.

Anaerobiosis↗
PubMedDate not supplied

Assisting manual dolphin identification by computer extraction of dorsal ratio.

Marine biologists use a measurement called the "Dorsal Ratio" in the process of manual identification of bottlenose dolphins. The dorsal ratio denotes the relative distances of the two largest notches from the tip on the dorsal fin. The manual computation of this ratio is time consuming, labor intensive, and user dependent. This paper presents a computer-assisted system to extract the dorsal ratio for use in identification of individual animals. The first component of the system consists of active contour modeling where the trailing edge of the dorsal fin is detected. This is followed by a curvature module to find the characteristic fin points: tip and two most prominent notches. Curvature smoothing is performed at various smoothing scales, and wavelet coefficients are utilized to select an appropriate smoothing scale. The dorsal ratio is then computed from the curvature function at the appropriate smoothing scale. The system was tested using 296 digitized images of dolphins, representing 94 individual dolphins. The results obtained indicate that the computer extracted dorsal ratio can be used in place of the manually extracted dorsal ratio as part of the manual identification process.

Algorithms↗