Computer assisted age progression.

A computer assisted method for altering the perceived age of a human face is presented. Our technique is based on calculating a trajectory or axis within a multi-dimensional space that captures the changes in large scale facial structure, shading and complexion associated with aging. Fine facial details associated with increasing age, such as wrinkles, are added to the aged face using a variation on a standard image processing technique called high boost filtering. The method is successfully applied to two-dimensional photographic images exhibiting uncontrolled variations in pose and illumination. Unlike our previous work on automated age progression, here the objective is to allow a certain degree of manual control over the process by the adjustment of three key progression-control-parameters. In the future this work may form the basis for a software tool to be used by forensic artists.

Variational solution for modal wave-front projection functions of minimum-error norm.

Common wave-front sensors such as the Hartmann or curvature sensor provide measurements of the local gradient or Laplacian of the wave front. The expression of wave fronts in terms of a set of orthogonal basis functions thus generally leads to a linear wave-front-estimation problem in which modal cross coupling occurs. Auxiliary vector functions may be derived that effectively restore the orthogonality of the problem and enable the modes of a wave front to be independently and directly projected from slope measurements. By using variational methods, we derive the necessary and sufficient condition for these auxiliary vector functions to have minimum-error norm. For the specific case of a slope-based sensor and a basis set comprising the Zernike circular polynomials, these functions are precisely the Gavrielides functions.

Gram-Charlier matched filter for Shack-Hartmann sensing at low light levels.

A study has been made of a Gram-Charlier matched filter for Shack-Hartmann sensing of wave-front slopes. The method is based on modeling the point-spread function by an expansion in terms of Gauss-Hermite polynomials. We present results for several subapertureycoherence area sizes both with and without CCD read noise. A more accurate estimation of the local slopes can be achieved at low light levels in this way than with the standard first-moment estimator.

Measurements of the four-point coherence function by the use of the coherence enhancement phenomenon.

We present laboratory results for measurements of the four-point coherence function of a spherical wave in the region of coherence enhancement after backscattering through turbulence. Experimental results are compared with the theoretical predictions. We conclude that the shape of the four-point coherence function in our experiment depends on the value of the inner scale of turbulence.

Use of polarization in interferometry after double passage through turbulence.

We report what are to our knowledge the first experimental results of coherence enhancement that use polarization to separate coherent and incoherent paths.

Effects of low temperature on in vivo and in vitro protein synthesis in Escherichia coli and Pseudomonas fluorescens.

The effects of temperature on protein synthesis by Escherichia coli, a mesophile, and Pseudomonas fluorescens, a psychotroph, were investigated by using whole-cell and cell extract preparations. After shifts to 5 degrees C, protein was synthesized at a slowly decreasing rate for 1 h by both organisms, after which P. fluorescens synthesized protein at a new rate corresponding to its 5 degrees growth rate, in contrast to E. coli which did not synthesize protein at a measurable rate. In vitro protein-synthesizing systems using MS-2 RNA, endogenous mRNA, and purified polysomes were utilized to investigate initiation of translation at 5 degrees C. In these systems, P. fluorescens cell extracts synthesized protein at linear rates for up to 2 h at 5 degrees C, whereas E. coli cell extracts synthesized protein for only 25 min at 5 degrees C. The rates of polypeptide elongation, as tested by the incorporation of phenylalanine into polyphenylalanine by cell extract protein-synthesizing systems from both organisms, were identical over the range of 25 to 0 degrees C. The polysome profiles of E. coli whole cells shifted from 37 to 5 degrees C showed accumulation of 70S ribosomal particles and ribosomal subunits at the expense of polysomes. Similar experiements done with P. fluorescens resulted in polysome reformation at 5 degrees C. In vitro experiments demonstrated that the 70S ribosomal particles, which accumulated in E. coli at 5 degrees C, were capable of synthesizing protein in vitro in the absence of added mRNA. These in vivo and in vitro results suggest that incubation of E. coli at subminimal temperatures results in a block in initiation of translation causing polysomal runoff and the accumulation of 70S particles, some of which are 70S monosomes.