Dual-frequency injection-locked continuous-wave near-infrared laser

We report a dual-frequency injection-locked continuous-wave near-infrared laser. The entire system consists of a Ti:sapphire ring laser as a power oscillator, two independent diode-lasers employed as seed lasers, and a master cavity providing a frequency reference. Stable dual-frequency injection-locked oscillation is achieved with a maximum output power of 2.8 W. As fundamental performance features of this laser system, we show its single longitudinal/transverse mode characteristics and practical power stability. Furthermore, as advanced features, we demonstrate arbitrary selectivity of the two frequencies and flexible control of their relative powers by simply manipulating the seed lasers.Comment: 8 pages, 4 figure

Generation of electromagnetic waves from 0.3 to 1.6 terahertz with a high-T-c superconducting Bi2Sr2CaCu2O8+delta intrinsic Josephson junction emitter

To obtain higher power P and frequency f emissions from the intrinsic Josephson junctions in a high-T-c superconducting Bi2Sr2CaCu2O8+delta single crystal, we embedded a rectangular stand-alone mesa of that material in a sandwich structure to allow for efficient heat exhaust. By varying the current-voltage (I-V) bias conditions and the bath temperature T-b, f is tunable from 0.3 to 1.6 THz. The maximum P of a few tens of mu W, an order of magnitude greater than from previous devices, was found at T-b similar to 55K on an inner I-V branch at the TM(1,0) cavity resonance mode frequency. The highest f of 1.6 THz was found at T-b = 10K on an inner I-V branch, but away from cavity resonance frequencies. A possible explanation is presented

BRAF Mutation Is Associated with Hyperplastic Polyp-Associated Gastric Cancer

Gastric hyperplastic polyps (GHP) are frequently found to be benign polyps and have been considered to have a low carcinogenic potential. The characteristics of the hyperplastic polyp-associated gastric cancer (HPAGC) remain unclear. Therefore, we analyzed samples from 102 GHP patients and identified 20 low-grade atypical GHPs (19.6%), 7 high-grade atypical GHPs (6.9%), and 5 intramucosal cancer samples (4.9%). GHP atypia was more common in the elderly and increased with increasing polyp size. In particular, polyps larger than 1 cm were associated with a higher grade and cancer. Furthermore, mucus production decreased with increasing atypia. Although no correlation was found between atypia and Helicobacter pylori infection or intestinal metaplasia, enhanced proliferative ability (Ki-67) did correlate with atypia, as did nuclear 8-hydroxy-2’-deoxyguanosine levels. Interestingly, 4-hydroxynonenal levels in granulation tissue and the area ratio of granulation tissue within polyps also correlated with GHP atypia. In five cases of HPAGC, three cases exhibited caudal type homeobox transcription factor (CDX2)-positive cells and a mixed mucin phenotype, which is considered to be related to H. pylori infection. By contrast, two cases were CDX2 negative, with a gastric mucin phenotype, and H. pylori infection was not observed in the tumor or the surrounding mucosa. In these cases, a v-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutation (V600E) was detected. All cancer samples showed high stemness and p53 protein accumulation, but no KRAS mutations. The molecular and phenotypic characteristics of the cases characterized by BRAF mutations may represent a novel subtype of HPAGC, reflecting a conserved pathway to oncogenesis that does not involve H. pylori infection. These findings are worthy of further investigation in a large-scale study with a substantial cohort of HPAGC patients to establish their clinical significance

Generation of electromagnetic waves from 0.3 to 1.6 terahertz with a high- T_c superconducting Bi₂Sr₂CaCu₂O_8+δ intrinsic Josephson junction emitter

To obtain higher power P and frequency f emissions from the intrinsic Josephson junctions in a high-Tc superconducting Bi2Sr2CaCu2O8+δ single crystal, we embedded a rectangular stand-alone mesa of that material in a sandwich structure to allow for efficient heat exhaust. By varying the current-voltage (I-V) bias conditions and the bath temperature Tb, f is tunable from 0.3 to 1.6THz. The maximum P of a few tens of µW, an order of magnitude greater than from previous devices, was found at Tb ~55K on an inner I-V branch at the TM(1,0) cavity resonance mode frequency. The highest f of 1.6THz was found at Tb=10K on an inner I-V branch, but away from cavity resonance frequencies. A possible explanation is presented