Subsurface banding of blended controlled-release urea can optimize rice yields while minimizing yield-scaled greenhouse gas emissions

Controlled-release urea(CRU)is widely reported to supply crop nitrogen(N)demand with one basal application,thus effectively replacing split applications of urea without diminishing grain yield and N use efficiency(NUE).However,its use for replacement for high-yield split applications of urea(CK)for rice is untested.In addition,the degree to which greenhouse gas(GHG)emissions in rice systems are affected when CRU is substituted for CK remains unclear.During 2017 and 2018,we sampled plant growth and gas emissions in a rice paddy field treated with three CRU types(sulfur-coated urea[SCU],polymer-coated urea[PCU],and bulk blended CRU[BBU])applied via two methods(surface broadcasting on the soil and subsurface banding at 5 cm depth),with CK as a control.The three CRUs led to different soil NH_(4)^(+)-N dynamics,and the N supply pattern under BBU was more beneficial for rice seedling establishment than under SCU and PCU,resulting in grain yield and NUE comparable to those under CK.CRU type showed no significant effect on either CH_(4) emissions or N_(2)O emissions,and broadcast CRUs exhibited significantly higher total GHG emissions than CK.However,banded CRUs significantly reduced the total GHG emissions in comparison with broadcast CRUs,by 9.2%averaged across the two years.Reduced CH_(4) emissions,particularly during the period prior to the middle drainage,contributed largely to the GHG difference.With comparably high grain yield and low total GHG emissions,banded BBU showed a low yield-scaled GHG(GHG emissions divided by grain yield)comparable to that under CK in both years.Overall,our study suggested that N management synchronized with rice demand and contributing to a high NUE tended to minimize yield-scaled GHG.Broadcast CRU can hardly substitute for CK in terms of either grain yield or GHG emissions,but banded BBU is a promising N management strategy for sustaining rice production while minimizing environmental impacts.

医疗美容类激光设备适用范围的审评要点

医疗美容类激光设备的适用范围与该类设备作用于人体的机制密切相关。该研究从医疗器械审评角度总结医疗美容类激光设备的适用范围,为注册人和技术审评部门科学、合理地评价该类设备的安全性和有效性提供参考。

一种面向SoC的能量迹预处理方法

差分功耗攻击技术是恢复密码设备密钥最有效的攻击手段之一,但在攻击过程中,如果使用不合适的采样点,将引入额外噪声,会降低攻击成功率。为此,提出了一种基于能量模型的能量迹分类方法,旨在定位能量迹中与密钥具有较强相关性的特征点。分别利用汉明距离和汉明重量2种能量模型定位特征点,截取特征点附近少量采样点构成特征区间。攻击不同密钥下载有128位AES算法的SoC芯片,实测结果表明:利用汉明距离能量模型得到的最佳特征区间的长度较短。最终,基于汉明距离能量模型得到的特征点定位方法具有较低的样本计算量,且缩减了大量的样本量。

医用激光设备动物试验的决策与审评要求探讨

医用激光设备是向人体靶组织输出能量的电气设备,动物试验是激光设备开展非临床/临床评价的重要手段之一,也可作为该类设备在临床试验前提供安全性和有效性的证据。本文通过参考现有医疗器械动物试验相关的法规、标准、指南,分析医用激光设备的作用机理;结合常见激光治疗设备的审评经验,概述了激光治疗设备决策开展动物试验研究的考量因素及规范要求;并举例分析了开展动物试验的目的、方案设计要求和评价指标;为医用激光治疗设备的动物试验研究提供参考,也可供该类医疗器械相关的技术审评人员及注册人员参考。

Mechanism analysis of radiation generated by the beam-plasma interaction in a vacuum diode

When we were studying the vacuum switch,we found that the vacuum diode can radiate a broadband microwave.The vacuum diode is comprised of a cathode with a trigger device and planar anode,there is not a metallic bellows waveguide structure in this device,so the radiation mechanism of the vacuum diode is different from the plasma filled microwave device.It is hard to completely imitate the theory of the plasma filled microwave device.This paper analyzes the breakdown process of the vacuum diode,establishes the mathematical model of the radiating microwave from the vacuum diode.Based on the analysis of the dispersion relation in the form of a refractive index,the electromagnetic waves generated in the vacuum diode will resonate.The included angle between the direction of the electromagnetic radiation and the initial motion direction of electron beam is 45 degrees.The paper isolates the electrostatic effect from the beam-plasma interaction when the electromagnetic radiation occurs.According to above analyses,the dispersion relations of radiation are obtained by solving the wave equation.The dispersion curves are also obtained based on the theoretical dispersion relations.The theoretical dispersion curves are consistent with the actual measurement time-frequency maps of the radiation.Theoretical deduction and experiments indicate that the reason for microwave radiating from the vacuum diode can be well explained by the interaction of the electron beam and magnetized plasma.

All-solid-state ultraviolet laser based on frequency doubling in an external ring cavity

An all-solid-state ultraviolet laser based on frequency doubling in an external ring cavity with low input pump power is reported. Both second harmonic generation （SHG） and fourth harmonic generation （PRIG） occurred in an external threemirrors ring cavity. The need for impedance matching of this cavity to the input radiation was eliminated and the cavity adaptation was simplified, because the mirrors were not highly reflecting at 1064 nm and the cavity resonates only at 532 rim. Experiment results demonstrate that the conversion efficiency of this external cavity is higher than that of the singlepass condition.

Text Understanding with a Hybrid Neural Network Based Learning

Teaching machine to understand needs to design an algorithm for the machine to comprehend documents. As some traditional methods cannot learn the inherent characters effectively, this paper presents a new hybrid neural network model to extract sentence-level summarization from single document,and it allows us to develop an attention based deep neural network that can learn to understand documents with minimal prior knowledge. The proposed model composed of multiple processing layers can learn the representations of features.Word embedding is used to learn continuous word representations for constructing sentence as input to convolutional neural network. The recurrent neural network is also used to label the sentences from the original document, and the proposed BAM-GRU model is more efficient. Experimental results show the feasibility of the approach. Some problems and further works are also present in the end.

医疗美容类激光产品技术审评的关注点

激光医学是生物医学与激光技术的交叉领域,激光产品作用于人体的作用机理与其预期用途息息相关。技术审评可从医疗器械安全有效基本要求出发,综合衡量激光产品的所有风险以及非预期影响,要求其均应最小化并可接受,在正常使用中受益大于风险。该文从医疗器械注册技术审评的角度,分析医疗美容类激光产品在医疗器械技术审评过程中的主要关注点,为注册人/申请人和技术审评部门科学、合理地评价医疗美容类激光产品的安全性、有效性提供参考。

美容用低能量光学类医疗器械的注册监管要求探讨

激光、强脉冲光等光学类医疗器械自20世纪80年代应用于美容领域以来,产品的技术和应用发展迅速。其中低能量的光学设备由于监管属性尚存争议,其生产、经营和使用情况混乱,具有较大的安全隐患。本文通过分析国际国内发布的相关标准、美国食品药品监督管理局(food and drug administration,FDA)出台的指南及我国已发布的相关指导原则,以期总结国内外相关经验,为此类产品在我国的注册监管提供思路和建议,确保上市产品的安全有效。

光电设备用于皮肤光老化及皱纹治疗的概况及审评关注点

对皮肤光老化及皱纹治疗的光电类设备的作用机制、产品类型进行梳理,并结合已获医疗器械注册证设备的性能参数、适用范围等批准情况及最新发布的指导原则,提出并总结此类产品的审评关注点。以期对该类产品的监管提供参考。

Association between circulating oxidized low-density lipoprotein and atherosclerotic cardiovascular disease

Atherosclerosis is a chronic, progressive disease which eventually leads to coronary heart disease (CHD), ischemic stroke and other atherosclerotic cardiovascular disease (ASCVD). Numerous studies have demonstrated an atherogenic role of oxidized low-density lipoprotein (ox-LDL) in the progression of ASCVD. This article briefly reviews the atherogenic mechanism of ox-LDL, the methods of measuring ox-LDL in the circulation, effect of medical therapy and life-style modification on ox-LDL level, and the association between circulating ox-LDL and atherosclerosis, including clinical ASCVD events and subclinical atherosclerosis, in observational studies.