ABSTRACT
An artificial subwavelength dielectric metalens (ML), the realization of being ultrathin and light-weight, provides a potential candidate with replacing a traditional bulky curved lens with a high image quality. A ML with 1.5 mm in diameter having numerical aperture (NA) $\sim{0.60}$â¼0.60 at the near-infrared wavelength of $\lambda = 0.94 \,\,{\unicode{x00B5}{\rm m}}$λ=0.94µm was designed by the finite-difference time-domain (FDTD) method with speeding up optimization of the MLs' scheme by the deep neural network (DNN) model. Additionally, an ultrathin high NA ML was achieved by cost effective semiconductor manufacturing technology. The fabricated ML can focus an incident light down to a spot as small as $ \sim{5.2}\,\,{\rm \unicode{x00B5}{\rm m}} $â¼5.2µm with high optical efficiency of $\sim{88.4}\% $â¼88.4% (focusing efficiency achieved, 23.7%). We also provided an efficient MLs' semiconductor manufacturing technology for the development of an optical device in near-infrared image technology.
ABSTRACT
BACKGROUND: This study evaluated the survival outcome and determined the prognostic factors for gastric cancer patients who underwent gastric resection in the past 6 years. METHODS: Between 1994 and 2000, a total of 1,322 patients with gastric cancer who underwent gastric resection in our hospital comprised the study subjects. Their mean age was 61.1 (range, 14-92) years. There were 865 male and 457 female patients. Total gastrectomy was performed in 389 (29.4%) and distal gastrectomy in 933 patients. Curative resection was performed in 961, and palliative resection in 361 patients. A D2 or greater lymphadenectomy was required for curative resection. Patients received postoperative chemotherapy if they underwent palliative resection. RESULTS: Early or pT1 gastric cancer accounted for 17.7% and lymph node metastasis for 62.1% of all resected cases. The overall operative mortality and morbidity rates were 3.3% and 18.0%, respectively. The operative mortality for palliative total gastrectomy was particularly high (8.5%). The overall cumulative 5-year survival rate of all resected patients was 45.6%, and it was 57.0% after curative resection. Multivariate analysis revealed that lymph node metastasis, serosal invasion, peritoneal seeding, positive resection margin, liver metastasis, old age, tumor size, and lymphatic invasion were independent prognostic factors. CONCLUSION: The most important prognostic factors for survival were lymph node metastasis, serosal invasion, peritoneal seeding, positive resection margin, liver metastasis, old age, tumor size, and lymphatic invasion. The operative mortality and survival outcome of our gastric cancer patients after gastric resection compared favorably with those of other series in other countries.
