A linear programming approach to on-line constrained optimal terrain-tracking systems

The idea of an optimal decision strategy is applied to a class of tracking problems. The resulting pointwise optimization problem is posed as a linear programming problem, in contrast to previous work where it is posed as a quadratic programming problem. A useful result concerning the convergence of the tracking error in the presence of control constraints is derived and applied to an aircraft terrain-following system.     

The effects of d-amphetamine,chlordiazepoxide and alpha-flupenthixol on food-reinforced tracking of a visual stimulus by rats

Rats were trained to respond to one of two levers under a random ratio schedule of food reinforcement. Which of the levers was correct was redetermined before each response and signalled by a light. The effects of d-amphetamine (0.2–3.2 mg/kg), chlordiazepoxide (1–8 mg/kg), and the neuroleptic alpha-flupenthixol (0.03–0.33 mg/kg) on the efficiency of rats tracking this visual cue were examined. d-Amphetamine increased the proportion of responses made on the correct lever at low and intermediate doses, but reduced the proportion at 3.2 mg/kg. At the highest dose, chlordiazepoxide produced a small increase in this measure, together with a reduction in response rate, but alpha-flupenthixol had no effect, even at a dose reducing response rate. Low doses of amphetamine also increased switching between the levers, producing a proportionately greater increase in switching from the correct lever to the incorrect lever than vice versa. The results are interpreted as showing that d-amphetamine facilitates tracking performance as a result of its action of enhancing response switching, and supporting the hypothesis that facilitation of performance by amphetamine-like drugs depends on the effect of the drug on response output coinciding with task requirements.     

The effect of marihuana on tracking task perfomance

A 5-min paced contour tracking task was performed before and after receiving brownies containing either placebo or marihuana calibrated to a ⁹-tetrahydrocannabinol content of 20 mg. The error patterns of 19 young male subjects who received placebo and 18 who received marihuana were compared. After marihuana there was an increase in total errors as measured by the standard deviation (P<0.01) and the mean deviation (P<0.02) error scores. Although marihuana is reputed to create a fluctuating effect, under the conditions of this experiment the variability of error scores between successive 15-second time periods in the marihuana group was not significantly greater than in the placebo group. In addition the marihuana deficit did not show significant time trends during the task.This research was supported by NIMH Grant MH 03030 and Veterans Administration Project 5019-02.The authors thank Dr. Helena Kraemer for statistical consultation.     

Improved preparation and physical studies of polybutylcyanoacrylate nanocapsules

An improved method for the preparation of alkylcyanoacrylate nanocapsules is proposed that involves the intermediate synthesis of a well defined adduct of a single monomer unit to an ethanol molecule. It leads to thinner capsule walls and, generally, to a more reproducible capsule structure. The chemical composition of the intermediate organic phase has been studied by nuclear magnetic resonance spectroscopy. The morphology and size of resulting structures is analysed, applying analytical ultracentrifugation and light microscopic particle tracking. The sizes of capsules prepared in the described manner depend on the concentrations of the oil and the monomer components, as is shown by the results of a set of experiments following a simple factorial design.     

三维斑点追踪技术评估正常儿童左心室纵向收缩功能

目的 观察年龄对心室纵向运动指标的影响,分析相关参数和年龄的关系,建立不同年龄、不同节段心肌的参考值.方法 3～15岁健康儿童60例,采用Toshiba Artida彩色多普勒超声显像诊断仪,记录左心室壁16节段纵向收缩期峰值应变、位移值及其达峰时间,并观察其随年龄变化情况.结果 峰值应变由心尖段向基底段递减,峰值位移由心尖段向基底段递增.心尖段达峰时间早于中间段与基底段.峰值应变除外A组vsC组侧壁中段(ML)、A组vsB组前壁心尖段(AA),其余节段各年龄组之间无明显差异.峰值位移随年龄增长有逐渐增加的趋势.应变、位移达峰时间有随年龄增加而增加的趋势.结论 峰值应变由心尖段向基底段递减,数值不受年龄影响;峰值位移由心尖段向基底段递增,数值随年龄增加而增加.应变、位移达峰时间心尖段早于中间段与基底段.     

三级综合医院预审结果分析与体会

依据《三级综合医院评审标准实施细则（2011版）》,由卫生部医院管理研究所医院评审评价项目办公室组织专家,对天津市4所三级综合医院进行预评审。概述了预评审过程与内容,阐述了追踪方法学的应用,指出了问题及改进方向。     

Real-time augmented model guidance for mandibular proximal segment repositioning in orthognathic surgery,using electromagnetic tracking

It is essential to reposition the mandibular proximal segment (MPS) as close to its original position as possible during orthognathic surgery. Conventional methods cannot pinpoint the exact position of the condyle in the fossa in real time during repositioning. In this study, based on an improved registration method and a separable electromagnetic tracking tool, we developed a real-time, augmented, model-guided method for MPS surgery to reposition the condyle into its original position more accurately.After virtual surgery planning, using a complex maxillomandibular model, the final position of the virtual MPS model was simulated via 3D rotations. The displacements resulting from the MPS simulation were applied to the MPS landmarks to indicate their final postoperative positions. We designed a new registration body with 24 fiducial points for registration, and determined the optimal point group on the registration body through a phantom study. The registration between the patient's CT image and physical spaces was performed preoperatively using the optimal points.We also developed a separable frame for installing the electromagnetic tracking tool on the patient's MPS. During MPS surgery, the electromagnetic tracking tool was repeatedly attached to, and separated from, the MPS using the separable frame. The MPS movement resulting from the surgeon's manipulation was tracked by the electromagnetic tracking system. The augmented condyle model and its landmarks were visualized continuously in real time with respect to the simulated model and landmarks.Our method also provides augmented 3D coronal and sagittal views of the fossa and condyle, to allow the surgeon to examine the 3D condyle–fossa positional relationship more accurately. The root mean square differences between the simulated and intraoperative MPS models, and between the simulated and postoperative CT models, were 1.71 ± 0.63 mm and 1.89 ± 0.22 mm respectively at three condylar landmarks. Thus, the surgeons could perform MPS repositioning conveniently and accurately based on real-time augmented model guidance on the 3D condyle positional relationship with respect to the glenoid fossa, using augmented and simulated models and landmarks.     

The National Lung Screening Trial's Endpoint Verification Process: determining the cause of death

Background

Randomized controlled trials (RCTs) evaluating cancer screening modalities usually employ cause-specific mortality as their primary endpoint. Because death certificate cause of death can be inaccurate, RCTs frequently use review committees to assign an underlying cause of death. We describe the National Lung Screening Trial's (NLST's) death review approach, the Endpoint Verification Process (EVP), which strives to minimize errors in assignment of cause of death due to lung cancer.

Methods

Deaths selected for review include those with a notation of lung cancer on the death certificate and those occurring among participants ever diagnosed with lung cancer. Other criteria that trigger death review include, but are not limited to, death within 6 months of a screen suspicious for lung cancer and death within 60 days of certain diagnostic evaluation procedures associated with a screen suspicious for lung cancer or a lung cancer diagnosis. EVP requires concordance on whether death was due to lung cancer. Deaths are first reviewed by the EVP chair. If concordance is not achieved, the death is next reviewed by an Endpoint Verification Team (EVT) member. If concordance between the chair- and member-assigned cause of death is not achieved, the death is next reviewed by a group of at least three EVT members. Cause of death is assigned at the step in which concordance was achieved, or if necessary, at the team review.

Conclusions

NLST's EVP is designed to produce a highly accurate count of lung cancer deaths.     

血管回声跟踪技术对妊娠期高血压疾病早期颈动脉弹性改变的临床研究

目的探讨血管回声跟踪技术在妊娠期高血压疾病中的应用价值。方法对正常妊娠女性35例和妊娠期高血压疾病患者32例(妊娠期高血压患者22例,子痫前期患者10例)应用ET技术检测双侧颈总动脉的硬化度(β)、弹性系数(Eρ)、动脉顺应性(AC)、膨大系数(AI)及单点脉搏波传导速度(PWVβ),及二维结构(IMT)的测量。并对所得数据进行统计学分析。结果妊娠期高血压疾病组β、Eρ、AI、PWVβ与正常妊娠组比较明显升高,AC降低,差异有显著性(P<0.05)。结论血管回声跟踪技术在评价妊娠期高血压疾病血管弹性、内皮功能方面具有一定的价值,能及早提示妊娠期高血压疾病患者的血管病变程度,为治疗及预防提供依据。     

核转染对成体骨髓源性干细胞的影响

背景：成体骨髓源性干细胞是实施细胞治疗的重要细胞来源。对成体骨髓源性干细胞的示踪,是研究其移行、分化的规律与机制并进一步阐明再生潜能、疗效的关键。 目的：探讨经转染后的成体骨髓呈克隆样干细胞,在细胞表型、增殖能力、心肌分化潜能是否存在的影响。 方法：应用核转染技术利用U-23程序将编码maxGFP报告基因的载体对成体骨髓呈克隆样干细胞进行转染,应用MTT法对核转染前后的生长曲线进行测定,使用3 μmol/L 5-氮胞苷对核转染前后成体骨髓呈克隆样干细胞进行向心肌分化诱导,并利用RT-PCR对向心肌分化的特异性标记物GATA4与MLC-2v的表达进行测定。使用成年SD大鼠心肌梗死左前降支结扎模型,对使用经maxGFP转染的成体骨髓呈克隆样干细胞施心内注射并于注射后的第2天和第7天对经注射心脏行冰冻切片并观察maxGFP在体内的表达情况。 结果与结论：经核转染24 h后,第47代及第119代成体骨髓呈克隆样干细胞的转染率为49.4%和43.1%,转染后5 h,开始出现呈绿色荧光阳性的细胞,经核转染后仍能保持小圆球形、可贴壁、呈克隆样生长。MTT检测结果显示：核转染前后第47代及第119代均具有相似的生长曲线。核转染前第47代及119代细胞平均群体倍增时间分别为8.57,10.28 h;核转染后分别为9.42,10.42 h,各代前后比较差异无显著性意义(P=0.551,P=0.774)。RT-PCR检测结果显示：核转染前5-氮胞苷处理前后均表达GATA4,处理后MLC-2v条带更强;核转染后5-氮胞苷处理前后均表达GATA4,处理后MLC-2v条带更强,上述2个向心肌分化指标于转染前后变化并不明显。体内实验结果：心内注射经核转染后的成体骨髓呈克隆样干细胞,第2天及第7天可在经注射心肌中发现有少量绿色荧光阳性的细胞。提示,核转染可快速地将外源基因导入细胞,经核转染后的成体骨髓呈克隆样干细胞仍能保持其细胞形态、增殖能力及向心肌分化潜能,然而,经maxGFP基因核转染的成体骨髓呈克隆样干细胞,移植入心肌后只有少数细胞能表达经转染基因。