RESUMO
Herein, we report a significant improvement in solar-pumped laser collection efficiency based on end-side pumping a 6-mm-diameter 95-mm-length Ce:Nd:YAG/YAG grooved bonded crystal rod. A Fresnel lens, quartz cooling-water tube, and gold-plated conical cavity constituted the solar-energy collection and concentration system, which was designed to maximum pump light absorption and minimize thermal effects in the Ce:Nd:YAG laser medium. To the best of our knowledge, this is the first time that a Ce:Nd:YAG crystal has been pumped by a Fresnel-lens solar-energy collection and concentration system. The 0.69-m2 effective solar-collection area produced 26.93 W of continuous-wave laser power, corresponding to 6.33% slope efficiency. The collection efficiency (38.8 W/m2) was 1.21 times higher than the highest previously reported value for Fresnel-lens solar collection, and is a record for single-beam solar-pumped lasers.
RESUMO
Realizing a high solar light conversion magnitude in Cr,Nd: YAG transparent ceramic is crucial to its applications in solar pumped solid state lasers. In this study, high quality Cr,Nd:YAG transparent laser ceramics with homogeneous microstructure and theoretical transmittance were fabricated, and an efficient laser oscillation of watt-level was realized by pumping ceramic at 808 nm. There were no any characteristic absorptions corresponding to Cr2+ or Cr4+ ions detected, even when the Cr3+ ion doping concentration reached 0.6 at.%. Increasing Cr3+ and Nd3+ doping concentrations significantly enhanced the emission intensity of ceramics at 1.06 µm, and energy transfer efficiency of the 0.3 at.% Cr,Nd: YAG ceramics was increased from 14.9% to 36.9% when increasing Nd3+ ion concentration from 0.3 at.% to 1.0 at.%, with an increasing magnitude of 247.6%. The results indicated that Cr,Nd: YAG transparent ceramic is a promising gain medium for solar pumped solid state lasers.
RESUMO
A mini-camera is one of several emerging cat-eye devices featuring tiny lenses with diffracted retro-reflections. It is hard for traditional active laser detection systems to identify a mini-camera because of their weak reflection. This paper proposes an anti-camera system with a spectrum-based convolutional neural network algorithm to recognize the profile features of the retro-reflection images captured by the system. The network was trained with the spatial spectra of local datasets and uploaded onto the embedded device. The results of several indoor experiments demonstrate that the system reached high accuracy in real-time detection, even with various types of interference.
RESUMO
To evaluate the association between severe pulmonary embolism events and bevacizumab, we conducted the first meta-analysis evaluating the incidence and risk of pulmonary embolism associated with bevacizumab-based therapy. We searched PubMed, EMBASE, Cochrane Library, and ClinicalTrials.gov up to September 2016 for randomized controlled trials comparing bevacizumab with no bevacizumab on cancer patients. Incidence rates, relative risks, and 95% confidence intervals were calculated using fixed- or random-effects models. The primary end point was the association of bevacizumab with pulmonary embolism. Subgroup analyses were performed according to tumor type, dose, and publication status. In total, 23 randomized controlled trials were included. For patients receiving bevacizumab, the overall incidence of severe pulmonary embolism events was 1.76% (95% confidence interval = 1.25%-2.27%). Cancer patients treated with bevacizumab did not increase the risk of pulmonary embolism events (relative risk = 1.00, 95% confidence interval = 0.80-1.25). No significant differences in pulmonary embolism incidence or risk among subgroup analyses were observed. No evidence of publication bias was observed. This study suggested that bevacizumab may not increase the risk of pulmonary embolism in cancer patients.