High-contrast imaging through scattering media using structured illumination and Fourier filtering

We show in this Letter a novel approach for high-contrast imaging through scattering media by combining structured illumination and Fourier filtering (SIF). To assess the image contrast enhancement at different image spatial frequencies, the modulation transfer function is calculated for four detection schemes: (1) no filtering, (2) Fourier filtering, (3) structured illumination, and (4) SIF filtering. A scattering solution consisting of D = 7.3 μm polystyrene spheres immersed in distilled water and illuminated at λ = 671 nm is used here. We demonstrate the possibility of obtaining, with SIF, an image contrast up to 60% at an optical depth of OD = 10, improving the contrast by a factor of 40 over conventional transmission imaging

Light-in-flight recording. 5: Theory of slowing down the faster-than-light motion of the light shutter

Light-in-flight recording by holography uses a picosecond pulse for the reference beam, which like a sheet of light intersects the hologram plate and produces a sensitivity area that with a speed faster than light moves over the plate like a light shutter. If, however, the front of the reference pulse by diffraction in a grating is tilted relative to its direction of motion, the velocity of the light shutter can be slowed down resulting in increased recording time. The practical result using a reflection grating was a true recording that corresponded to a time compression of two to one. To minimize distortions of the recorded pulse shape we studied intersections that are identical for apparent (ellipsoidal) and true (spheroidal) wavefronts

Transitions Within the n = 4 Complex of Kr VII Obtained from a Theta-Pinch Light Source

The spectrum of six times ionized krypton (Kr VII) has been observed in the 430-1000 A wavelength range and 23 lines have been identified as transitions between levels of the 4s2, AsAd. Ap2 and AsAp configurations. For 13 of the lines the classification is new. Revised values are proposed for three levels while for the rest the uncertainty in the existing level values has been considerably decreased. The results are supported by isoelectronic comparisons along the Zn 1 isoelectronic sequence. The configurations are interpreted by fitting the theoretical energy expressions to the observed energy levels using least- squares techniques. The parameter values are compared with results from Hartree-Fock calculations

Raytracing in the compensation of the peripheral optics of the eye

Abstract Background: Many people with a visual impairment have only peripheral vision. However, there is limited knowledge of the peripheral optics of the eye and only some measurements are available in this field. Methods: We simulated the paths of peripheral rays through the eye by means of raytracing. Five programs were compared. The OSLO raytracing software proved to be not only the best one in these circumstances but we also found it very well suited to our purpose. Remaining uncertainties are entirely due to a lack of input data about the peripheral part of the optical system of the eye. We designed compensatory optics on the basis of the test results. Results: Lenses have been manufactured in accordance with the calculations made by the program for angles of incidence of 20, 40, and 60 degrees. The lenses are high compensation astigmatic lenses. The results of perimeter examinations of changes in peripheral vision using attachment optics were inconclusive, while tests of the lenses as attachments in front of a fundus camera produced successful preliminary results. Conclusion: The next step is to test peripheral vision compensatory optics in traffic situations (driving simulator). At the same time attempts are being made to find methods and instruments for measuring the peripheral optics of the eye. Keywords: astigmatism, central scotoma, raytracing, macula degeneration, peripheral vision

High-speed structured planar laser illumination for contrast improvement of two-phase flow images

A high-speed method to remove blurring effects caused by multiple scattering in planar laser images of two-phase flows is demonstrated. The technique is based on structured illumination and is for the first time to our knowledge applied on a dynamic medium. As structured illumination requires three successive images to be recorded and to freeze the flow motion in time, a high-speed laser and imaging system is employed. We show that by using a time delay of 55 us between the images a single-shot representation of a dilute flow of water droplets can be achieved. By having an additional inner stream with known structure and composition, the efficiency of the method is quantitatively evaluated, showing an increase from 58% to 93% in image contrast. Such an improvement allows more accurate analysis and interpretation of scattering two-phase flow images. (C) 2008 Optical Society of Americ

Relation between smoking history and gene expression profiles in lung adenocarcinomas

Background: Lung cancer is the worldwide leading cause of death from cancer. Tobacco usage is the major pathogenic factor, but all lung cancers are not attributable to smoking. Specifically, lung cancer in never-smokers has been suggested to represent a distinct disease entity compared to lung cancer arising in smokers due to differences in etiology, natural history and response to specific treatment regimes. However, the genetic aberrations that differ between smokers and never-smokers' lung carcinomas remain to a large extent unclear. Methods: Unsupervised gene expression analysis of 39 primary lung adenocarcinomas was performed using Illumina HT-12 microarrays. Results from unsupervised analysis were validated in six external adenocarcinoma data sets (n=687), and six data sets comprising normal airway epithelial or normal lung tissue specimens (n=467). Supervised gene expression analysis between smokers and never-smokers were performed in seven adenocarcinoma data sets, and results validated in the six normal data sets. Results: Initial unsupervised analysis of 39 adenocarcinomas identified two subgroups of which one harbored all never-smokers. A generated gene expression signature could subsequently identify never-smokers with 79-100% sensitivity in external adenocarcinoma data sets and with 76-88% sensitivity in the normal materials. A notable fraction of current/former smokers were grouped with never-smokers. Intriguingly, supervised analysis of never-smokers versus smokers in seven adenocarcinoma data sets generated similar results. Overlap in classification between the two approaches was high, indicating that both approaches identify a common set of samples from current/former smokers as potential never-smokers. The gene signature from unsupervised analysis included several genes implicated in lung tumorigenesis, immune-response associated pathways, genes previously associated with smoking, as well as marker genes for alveolar type II pneumocytes, while the best classifier from supervised analysis comprised genes strongly associated with proliferation, but also genes previously associated with smoking. Conclusions: Based on gene expression profiling, we demonstrate that never-smokers can be identified with high sensitivity in both tumor material and normal airway epithelial specimens. Our results indicate that tumors arising in never-smokers, together with a subset of tumors from smokers, represent a distinct entity of lung adenocarcinomas. Taken together, these analyses provide further insight into the transcriptional patterns occurring in lung adenocarcinoma stratified by smoking history