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Biomedical subjects

John Girkin

Publications and source records attributed to John Girkin.

5 recordsLinked to original sources
PubMed2006

Polarization and image rotation induced by a rotating dielectric rod: an optical angular momentum interpretation.

When light is transmitted along the axis of a rotating glass rod, the polarization of the light is rotated through a small angle [Proc. R. Soc. London, Ser. A349, 423 (1976)]. Under the same conditions, we predict a rotation of the transmitted image by exactly the same angle. The treatment of the two effects in terms of light's spin and orbital angular momentum suggests that they share a common origin.

Journal Article↗
PubMed2005

Creating permanent 3D arrangements of isolated cells using holographic optical tweezers.

We report the creation of permanent 3D configurations of cells, at predefined positions, within a gelatin matrix. The technique used holographic optical tweezers to manipulate individual E. coli within a solution comprising monomer precursors. The matrix was then set and after the laser beam was removed, we were able to demonstrate that the structures remained intact for many days. We were also able to demonstrate that, in the presence of appropriate nutrients, the E. coli survived within the gelatin matrix for several days. The technique could have a number of potential future applications, including the arrangement of a variety of different cell types in complex architectures, as motifs for promoting tissue differentiation and growth within the field of cell engineering.

Cell Separation↗
PubMed2005

A preliminary investigation of a spectroscopic technique for the diagnosis of natural caries lesions.

OBJECTIVE: To report the use of spectroscopic analysis of dental fluorescence excited with a blue InGaN laser diode operating at 405 nm. METHOD: The spectra resulting from three classifications of smooth surface non-cavitated caries lesions (dull, shiny, brown) with 20 samples in each group were examined using the ratio of integrated fluorescence intensity in two spectral bands. RESULTS: All lesions demonstrated spectra which were significantly different from sound tooth structure. As expected, the 'brown' lesions demonstrated a significantly different spectral profile from the two white spot lesion classifications. Dull and shiny lesions had significantly different spectral measurements when examining the ratio of the integrated fluorescence in spectral bands between 480-500 and 620-640 nm. CONCLUSION: This method has application for detection of dental caries as well as demonstrating potential application to evaluate lesions which may represent different degrees of caries activity.

Analysis of Variance↗