Cost saving by reloading the multiband ligator in endoscopic esophageal variceal ligation: A proposal for developing countries

AIM:To assess the cost savings of reloading the multiband ligator in endoscopic esophageal variceal ligation (EVL) used on the same patient for subsequent sessions. METHODS:This single centre retrospective descriptive study analysed patients undergoing variceal ligation at a tertiary care centre between 1st January, 2003 and 30th June, 2006. The multiband ligator was reloaded with six hemorrhoidal bands using hemorrhoidal ligator for the second and subsequent sessions. Analysis of cost saving was done for the number of follow-up sessions for the variceal eradication. RESULTS:A total of 261 patients underwent at least one session of endoscopic esophageal variceal ligation between January 2003 and June 2006. Out of 261, 108 patients (males 67) agreed to follow the eradication program and underwent repeated sessions. A total of 304 sessions was performed with 2.81 sessions per patient on average. Thirty-two patients could not complete the programm. In 76 patients (70%), variceal obliteration was achieved. The ratio of the costs for the session with reloaded ligator versus a session with a new ligator was 1:2.37. Among the patients who completed esophageal varices eradication, cost saving with reloaded ligator was 58%. CONCLUSION:EVL using reloaded multiband ligators for the follow-up sessions on patients undergoing variceal eradication is a cost saving procedure. Reloading the ligator thus is recommended especially for developing countries where most of the patients are not health insured.

GYRO BIAS ON-ORBIT CALIBRATION FOR MICRO SATELLITES

According to gyro application in micro-satellites, a new gyro bias real-time on-orbit calibration technology is presented and it is independent of any other sensors. The approach relies on gyro on-orbit measurements restricted by satellite attitude dynamics and estimates the gyro bias generated when the gyro is electrified. Observability of the calibration model is analyzed and applicable conditions of the technology are derived. Simulation results indicate that the calibration algorithm is accurate and robust at gyro sampling rate, and its convergence speed is fast. Within the given attitude dynamics model error, the convergence time is less than 100 s and the convergence accuracy is about 1.0 （°）/h. Calibration performance can meet requirements of spacecraft operations.

氯吡格雷“重装上阵”:AMYDA-4 RELOAD研究的启示

作为血小板二磷酸腺苷(ADP)受体的拮抗剂,氯吡格雷的问世在动脉粥样血栓事件的预防以及经皮冠状动脉介入治疗(percutaneous transluminal coronary intervention,PCI)围手术期抗栓治疗领域可谓为一场革命。

重载4周模拟失重大鼠可部分恢复海马神经元新生和突触结构

目的研究重载4周模拟失重大鼠海马区神经元新生和突触结构的变化。方法雄性SD大鼠随机分为笼内对照组(Ctrl组)、尾吊组(SUS组)和尾吊+重载组(SUS+Reloading组)。分别使用旷场实验检测大鼠的情绪状态,新物体识别实验检测大鼠认知功能。采用免疫荧光染色和Western blotting检测海马区神经元新生能力。使用Golgi-Cox染色观察海马区突触结构的改变。结果旷场实验表明,SUS和SUS+Reloading两组大鼠中央活动路程及时间均显著减少(P<0.05);新物体识别实验结果表明,SUS组大鼠新物体辨别指数下降(P<0.01),SUS+Reloading组大鼠则提高(P<0.05)。免疫荧光染色及Western blotting结果表明,SUS组大鼠海马区新生神经元荧光密度及蛋白表达量均显著减少(P<0.01);Golgi-Cox染色结果提示模拟失重导致海马区突触结构完整性及树突棘密度降低(P<0.01);以上实验结果在重载4周模拟失重大鼠中均可得到显著改善(P<0.05)。结论模拟失重损伤大鼠海马神经元新生和突触的发育,此损伤在重载4周后可得到部分逆转。

On-orbit sleep problems of astronauts and countermeasures

Sufficient sleep duration and good sleep quality are crucial to ensure normal physical and mental health, cognition and work performance for the common people, as well as astronauts. On-orbit sleep problem is very common among astronauts and has potential detrimental influences on the health of crewmembers and the safety of flight missions. Sleep in space is becoming a new medical research frontier. In this review we summarized on-orbit sleep problems of astronauts and six kinds of causes, and we presented the effects of lack of sleep on performance as well as mental and physical health, then we proposed seven kinds of countermeasures for sleep disturbance in spaceflight, including pharmacologic interventions, light treatment, crew selection and training, Traditional Chinese Medicine and so on. Furthermore, we discussed and oriented the prospect of researches on sleep in space.

基于Flush+Reload的DES算法Cache计时攻击

在数据加密标准(DES)算法上使用Flush+Reload方法的Cache计时攻击,存在难以确定S盒元素行偏移位的问题。为此,利用S盒在Cache中会发生不对齐分布的特征,提出一种偏移位确定方法。采用clflush指令刷新Cache地址行,以驱逐Cache中DES算法的S盒信息,确定S盒元素的位置信息。利用密码算法在查询S盒时泄露的Cache计时信息获取明文与密钥异或后的中间态值,并通过该值和已知明文的相关性恢复密钥。实验结果表明,该方法能够有效确定S盒元素的行偏移位,提高针对DES算法Cache计时攻击的效率。

On-orbit target tracking and inspection by satellite formation

A new type of estimator is developed for the satellite formation to track and inspect on-orbit targets. The follower satellite in the formation works without relative sensors, and its target pointing commands are derived based on relative orbital dynamics. The centralized estimator based on truth measurement is designed, however, this estimator is proved unstable because of the lack of necessary measurement information. After that, an alternative estimator based on pseudo measurement is designed, and its observability and controllability are analyzed to qualitatively evaluate the convergence performance. Finally, an on-orbit target inspection scenario is numerically simulated to verify the performance of the estimator based on pseudo measurement.

On-orbit Geometric Calibration of Linear Push-broom Optical Satellite Based on Sparse GCPs

The paper presents a geometric calibration method based on the sparse ground control points (GCPs), aiming to the linear push-broom optical satellite. This method can achieve the optimal estimate of internal and external parameters with two overlapped image pair along the charge-coupled device (CCD), and sparse GCPs in the image region, further get rid of the dependence on the expensive calibration site data. With the calibrated parameters, the line of sight (LOS) of all CCD detectors can be recovered. This paper firstly establishes the rigorous imaging model of linear push-broom optical satellite based on its imaging mechanism. And then the calibration model is constructed by improving the internal sensor model with a viewing-angle model after an analysis on systematic errors existing in the imaging model is performed. A step-wise solution is applied aiming to the optimal estimate of external and internal parameters. At last, we conduct a set of experiments on the ZY-3 NAD camera and verify the accuracy and effectiveness of the presented method by comparison.

GF-5 VIMI On-Orbit Calibration Instrument and Performance

The Visible and Infrared Multispectral Imager (VIMI) is one of the main payloads of the GF-5 satellite. It has 12 spectral bands covering the wavelength from visible light to thermal infrared. The imager designed life is 8 years. In order to monitor and correct the radiometric performance of the imager for a long time and meet the user’s demand for the quantitative remote sensing application, the expandable diffuser used for calibration in full FOV and full optical path method is designed. The solar diffuser is installed on the front side of the optical system and does not affect the normal imaging of VIMI. When VIMI need calibration, the diffuser is expand to the front of optical system via the driving mechanism. According to the characteristics of the GF-5 satellite orbit, the requirement of the calibration energy and the installation matrix of the imager relative to the satellite, the expansion angle of the diffuser is 39 degrees. The 430 mm × 430 mm large-size PTEE diffuser is manufactured to ensure full FOV and full optical path calibration. The diffuser’s directional hemispherical reflectance is higher than 95% from 420 nm to 2400 nm and variation of BRDF in the direction of imager observation is better than 2.5%. The diffuser stability monitoring radiometer is designed to monitor the on-orbit attenuation performance of the diffuser. Results of ground simulation experiments and preliminary on-board calibration experiments were introduced.

Calibration chain design based on integrating sphere transfer radiometer for SI-traceable on-orbit spectral radiometric calibration and its uncertainty analysis

In order to satisfy the requirement of SI-traceable on-orbit absolute radiation calibration transfer with high accuracy for satellite remote sensors,a transfer chain consisting of a fiber coupling monochromator（FBM） and an integrating sphere transfer radiometer（ISTR） was designed in this paper.Depending on the Sun,this chain based on detectors provides precise spectral radiometric calibration and measurement to spectrometers in the reflective solar band（RSB） covering 300–2500 nm with a spectral bandwidth of 0.5–6 nm.It shortens the traditional chain based on lamp source and reduces the calibration uncertainty from 5% to 0.5% by using the cryogenic radiometer in space as a radiometric benchmark and trap detectors as secondary standard.This paper also gives a detailed uncertainty budget with reasonable distribution of each impact factor,including the weak spectral signal measurement with uncertainty of 0.28%.According to the peculiar design and comprehensive uncertainty analysis,it illustrates that the spectral radiance measurement uncertainty of the ISTR system can reach to 0.48%.The result satisfies the requirements of SI-traceable on-orbit calibration and has wider significance for expanding the application of the remote sensing data with high-quality.

Multi-Feature Fusion Based Relative Pose Adaptive Estimation for On-Orbit Servicing of Non-Cooperative Spacecraft

On-orbit servicing, such as spacecraft maintenance, on-orbit assembly, refueling, and de-orbiting, can reduce the cost of space missions, improve the performance of spacecraft, and extend its life span. The relative state between the servicing and target spacecraft is vital for on-orbit servicing missions, especially the final approaching stage. The major challenge of this stage is that the observed features of the target are incomplete or are constantly changing due to the short distance and limited Field of View (FOV) of camera. Different from cooperative spacecraft, non-cooperative target does not have artificial feature markers. Therefore, contour features, including triangle supports of solar array, docking ring, and corner points of the spacecraft body, are used as the measuring features. To overcome the drawback of FOV limitation and imaging ambiguity of the camera, a "selfie stick" structure and a self-calibration strategy were implemented, ensuring that part of the contour features could be observed precisely when the two spacecraft approached each other. The observed features were constantly changing as the relative distance shortened. It was difficult to build a unified measurement model for different types of features, including points, line segments, and circle. Therefore, dual quaternion was implemented to model the relative dynamics and measuring features. With the consideration of state uncertainty of the target, a fuzzy adaptive strong tracking filter( FASTF) combining fuzzy logic adaptive controller (FLAC) with strong tracking filter(STF) was designed to robustly estimate the relative states between the servicing spacecraft and the target. Finally, the effectiveness of the strategy was verified by mathematical simulation. The achievement of this research provides a theoretical and technical foundation for future on-orbit servicing missions.

On-orbit Geometric Calibration and Preliminary Accuracy Evaluation of GF-14 Satellite

GF-14 satellite is a new generation of sub-meter stereo surveying and mapping satellite in China,carrying dual-line array stereo mapping cameras to achieve 1∶10000 scale topographic mapping without Ground Control Points(GCPs).In fact,space-based high-precision mapping without GCPs is a challenging task that depends on the close cooperation of several payloads and links,of which on-orbit geometric calibration is one of the most critical links.In this paper,the on-orbit geometric calibration of the dual-line array cameras of GF-14 satellite was performed using the control points collected in the high-precision digital calibration field,and the calibration parameters of the dual-line array cameras were solved as a whole by alternate iterations of forward and backward intersection.On this basis,the location accuracy of the stereo images using the calibration parameters was preliminarily evaluated by using several test fields around the world.The evaluation result shows that the direct forward intersection accuracy of GF-14 satellite images without GCPs after on-orbit geometric calibration reaches 2.34 meters(RMS)in plane and 1.97 meters(RMS)in elevation.

A parallel pipeline connected-component labeling method for on-orbit space target monitoring

The paper designs a peripheral maximum gray differ-ence(PMGD)image segmentation method,a connected-compo-nent labeling(CCL)algorithm based on dynamic run length(DRL),and a real-time implementation streaming processor for DRL-CCL.And it verifies the function and performance in space target monitoring scene by the carrying experiment of Tianzhou-3 cargo spacecraft(TZ-3).The PMGD image segmentation method can segment the image into highly discrete and simple point tar-gets quickly,which reduces the generation of equivalences greatly and improves the real-time performance for DRL-CCL.Through parallel pipeline design,the storage of the streaming processor is optimized by 55%with no need for external me-mory,the logic is optimized by 60%,and the energy efficiency ratio is 12 times than that of the graphics processing unit,62 times than that of the digital signal proccessing,and 147 times than that of personal computers.Analyzing the results of 8756 images completed on-orbit,the speed is up to 5.88 FPS and the target detection rate is 100%.Our algorithm and implementation method meet the requirements of lightweight,high real-time,strong robustness,full-time,and stable operation in space irradia-tion environment.

Overview of Key Technologies and On-orbit Verification of China Space Station

Tiangong space station is a space station independently designed and developed by China.In order to build and operate the space station,it was necessary to make breakthroughs in many fields and master several key technologies,which were characterized over a long technological span and underwent difficult verifications.Therefore,in addition to ground verification,on-orbit flight tests of key technologies for the assembly,construction and operation of the space station were planned to be conducted used by the core module,taking into account the differences in the gravity environment between space and the Earth,in order to lay a foundation for the subsequent comprehensive assembly,construction and long-term on-orbit operation of the space station.In this paper,the mission characteristics of the space station are briefly introduced,along with the key technologies for the assembly and construction of the space station,and then the on-orbit verification tests are comprehensively introduced.

Windows Server Reloaded重装Windows服务器须知

用Windows 2000 Server或者Windows Server 2003作服务器，不可避免会碰到服务器崩溃，或者系统运行速度极慢，需要重新安装Windows的时候，其中在安装前后管理员最头疼的是各种设置、数据的备份和恢复。

暴一代重装上阵Reloaded

2004-2005,恼人的赛季,恼人的夏天,恼人的总决赛,恼人老梆子。你记住或许只有邓肯、华莱士、比卢普斯或者霍里,最多一个吉诺比例挽回些颜面,但阿根廷人本该获得MVP的,可惜我们又发现,他也开始老了。托尼·帕克?抱歉,他得到的更多是语无伦次的攻击以及用心险恶的绯闻。从2005年4月开始,暴一代消失了,勒布朗·詹姆斯?基里连科?卡梅隆·安东尼?即使大热的德怀恩·韦德一样难免吞下失败苦水,曾经风光无限的暴一代何时苦尽甘来?从未像今天这样企盼新赛季的到来,希望那是一个全新的开始,一个新的起点,一如当年暴一代乍现江湖,来吧,让我们重装上阵,让久违的暴一代重新上路。

冲击加载-卸载-再加载条件下Cr-Ni-Mo钢的层裂损伤

基于一级轻气炮加载技术,利用不同类型的多层复合飞片,实现了冲击加载-卸载-再加载路径,结合回收表征以及一维流体力学模拟,对Cr-Ni-Mo钢在冲击加载-卸载-再加载路径下的层裂损伤行为进行了深入研究。结果表明,在冲击加载-卸载-再加载路径下,层裂面会重新闭合并形成微损伤带,而孔洞位置仍然位于原奥氏体边界和板条群边界处,裂纹仍保持穿晶+沿晶的混合断裂模式。此外,第1层飞片与样品之间存在的较大阻抗差异会导致自由面速度中的再加载信号缺失。这些发现为深入理解Cr-Ni-Mo钢在复杂加载路径下的层裂行为提供了重要参考。

砾粒土卸载-再加载力学特性大型平面应变试验研究

针对水利和交通工程中平面应变类工程重复加卸荷问题,利用压力室平面应变改造后的西安理工大学大型土工真三轴仪在不同围压条件下对两种砾粒土进行固结排水平面应变卸载-再加载试验,研究了砾粒土在平面应变状态下的应力-应变关系和卸载回弹应变和卸载-再加载回弹坡度等力学特性。结果表明:砾粒土的颗粒圆度、孔隙比、母岩强度和围压均会影响剪切峰值应力及剪胀特性,颗粒圆度好、孔隙比小的砾粒土峰值应力较低且更易表现出剪胀特性,母岩强度低会促进应变软化并降低峰值应力,围压增大可抑制剪胀并使峰值应力增大;体积应变和广义剪应变卸载回弹量与应力水平和围压有关;回弹坡度随应力水平增大先增后减,密实度较大时回弹坡度较大;卸载-再加载过程中出现主应力轴旋转现象,零应变方向的应力并非一直为中主应力;回弹坡度显著大于初始切线坡度,回弹坡度与初始切线坡度之比随围压增大快速减小。

爆炸加载TC4 ELI钛合金微损伤研究

用TNT炸药空中爆炸加载等轴组织TC4 ELI钛合金板材,研究爆炸药量及距靶板中心距离对钛合金显微组织演化的影响,测试了爆炸加载后材料的力学性能。结果表明:爆炸加载后TC4 ELI钛合金显微组织内产生了大量形变带,形变带宽度为10~120μm;随着爆炸药量从200 g提高到300 g,形变带的数量及总宽度增加,形变带边界更加清晰;随着距靶板中心距离的增加,形变带数量不变,宽度增加。对爆炸加载回收靶板采用分离式霍普金森压杆(SHPB)进行动态压缩再加载试验,随药量和距靶板中心距离的增加,钛合金静动态抗压强度与断裂应变增加。动态再加载后产生了绝热剪切转变带,形变带对转变带的萌生及扩展过程影响较小。