No abstract

While numerous 3D imaging technologies exist, each addressing niche applications with varying degrees of success, none have achieved the breadth of applicability and impact that digital image sensors have achieved in the 2D imaging world [3][4][5][6][7][8][9][10] . A large-scale two-dimensional array of coherent detector pixels operating as a light detection and ranging (LiDAR) system could serve as a universal 3D imaging platform. Such a system would offer high depth accuracy and immunity to interference from sunlight, as well as the ability to directly measure the velocity of moving objects 11 . However, due to difficulties in providing electrical and 1 photonic connections to every pixel, previous systems have been restricted to fewer than 20 pixels [12][13][14][15] . Here, we demonstrate the first large-scale coherent detector array consisting of 512 (32 × 16) pixels, and its operation in a 3D imaging system. Leveraging recent advances

Cross-polarization magic-angle spinning solid-state NMR spectroscopy has been used to investigate the dependence of 13 C sugar chemical shifts on specific conformational parameters of a variety of ribonucleotides and ribonucleosides. Solid-state NMR is a valuable tool for nucleoside and nucleotide structural studies since it provides the means to acquire spectra that correspond to single conformations, as opposed to 13 C solutionNMRmethods. The distinct effects of sugar puckering on the C1′, C4′, and C5′ resonances of C2′ endo (S type) and C3′ endo (N type) furanoid conformations allow us to separate them into two groups. Further analysis of each group reveals an additional dependence of the C1′ and C5′ resonances on the glycosidic and C4′-C5′ exocyclic torsion angles, respectively. However, it is found that the glycosidic conformation cannot independently be determined from sugar 13 C chemical shift data. The statistical methods of exploratory data analysis and discriminant analysis are used to construct two canonical coordinates-linear combinations of chemical shifts which give the statistically optimal determination of the conformation from the NMR data.

Aims-To report the results of a series of patients who were treated with LASIK to correct post penetrating keratoplasty ametropia. Methods-26 eyes of 24 patients underwent LASIK to correct astigmatism and myopia after corneal transplantation; 14 eyes also received arcuate cuts in the stromal bed at the time of surgery. The mean preoperative spherical equivalent was −5.20D and the mean preoperative astigmatism was 8.67D. Results-The results of 25 eyes are reported. The mean 1 month values for spherical equivalent and astigmatism were −0.24D and 2.48D respectively. 18 eyes have been followed up for 6 months or more. The final follow up results for these eyes are −1.91D and 2.92D for spherical equivalent and astigmatism. The patients undergoing arcuate cuts were less myopic but had greater astigmatism than those not. The patients receiving arcuate cuts had a greater target induced astigmatism, surgically induced astigmatism, and astigmatism correction index than those eyes that did not. One eye suVered a surgical complication. No eyes lost more than one line of BSCVA and all eyes gained between 0 and 6 lines UCVA. Conclusions-LASIK after penetrating keratoplasty is a relatively safe and eVective procedure. It reduces both the spherical error and the cylindrical component of the ametropia. Correction of high astigmatism may be augmented by performing arcuate cuts in the stromal bed. (Br J Ophthalmol 1999;83:1013-1018

Laser in situ keratomileusis appears to be effective in correcting refractive error following cataract surgery. Longer-term studies are required to determine refractive stability.