美国中东政策评析

美国在中东遇到大麻烦,主要战略目标未能实现。伊拉克安全形势持续严峻,巴以和谈停滞不前,伊朗核问题难以解决,压叙利亚屈服迄未奏效,恐怖活动越反越多,大中东改造计划受挫。美遇到的困难未超出其承受能力,美国在中东仍居主导地位,美中东政策在手法和策略上有所调整,实质上并无变化。     

Measurement of diet in a large national survey: comparison of computerized and manual coding of records in household measures

A diary method using household measures was employed to obtain dietary records in a large national prospective survey and a computer program, DIDO (Diet In Data Out), was designed for direct entry of the diaries. The accuracy of this computerized coding system was examined alongside that of the manual coding used for a similar diary in a previous wave, 7 years earlier, of the same survey. Accuracy was assessed by analysis of the errors in the coded and checked records by stringent re-checking of nominal 2% random subsamples of the diet diaries coded by each method. The mean time to code and check each of the 2086 7-day records in the whole survey using DIDO was 58 minutes (SD 30) compared with reported results of 1–4 hours for manual methods. The mean error rate of computerized coding and checking with DIDO was 2.3% (SD 2.1; range 0–8.9) per diary in the subsample. Correcting these mistakes made insignificant changes to the calculated mean energy and nutrient intakes for the subsample. The percentage of individuals changing to an adjacent third of nutrient distribution after correcting unambiguous errors ranged from none (for alcohol) to 11% (for carbohydrate and calcium intake). The mean error rate on a similar subsample of diaries from the earlier survey which had been coded manually was significantly higher at 5.9% (SD 4.1; range 0–17) per diary. Emphasis is laid on the importance, in coding, of dealing with ambiguities in the subjects' records, since this can affect the accuracy and the precision of the nutrient results obtained. We conclude that the DIDO coding method has the advantages of greater accuracy, speed, consistency and efficient data handling, and affords greater data accessibility for checking, compared with manual systems.     

实用型射野照相用标尺板的研制与应用

介绍一种实用型标尺板的研制方法,并将其应用在放疗射野照相工作中,从而得到了摆位误差的真实测量数据,有效地提高了放疗摆位中体位验证的精度,是加强放疗质量管理和质量控制的有效手段。     

Death certification and coding for ischaemic heart disease in Tasmania

Official records show that the rates of mortality from ischaemic heart disease (IHD) in Tasmania have been the highest of all the Australian states for most of the past decade. This study assesses the accuracy of the official Tasmanian mortality data for IHD in 1987 and 1988 for males aged 25 to 74 years using routinely available clinical and pathological data supplemented by information from the attending doctor. Our findings show that a death officially coded to ICD 9 rubrics 410–414 (IHD) in Tasmania has 94% sensitivity and a positive predictive value of 90% for fatal definite acute myocardial infarction or possible coronary death as defined by the WHO. Comparison of our results with those of two earlier studies undertaken in Australian mainland centres indicates that differences in the official statistics for coronary mortality between Tasmania and the mainland states reflect true differences in the risk of coronary death. While the results from three Australian studies suggest that the routine system of death certification is reasonably accurate, careful monitoring of death certification and coding practices need to be undertaken regularly in all states of Australia if secular changes in regional patterns of coronary mortality are to be regarded as credible. (Aust NZ J Med 1992; 22: 114–118.)     

Short utterance recognition using a network with minimum training

A feedforward network is used to recognize short, digitized, isolated utterances. A high, multispeaker recognition rate is achieved with a small vocabulary with a single training utterance. This approach makes use of the pattern recognition property of the network architecture to classify different temporal patterns in the multidimensional feature space. The network recognizes the utterances without the need of segmentation, phoneme identification, or time alignment. We train the network with four words spoken by one single speaker. The network is then able to recognize 20 tokens spoken by 5 other speakers. We repeat the above training and testing procedure using a different speaker's utterances for training each time. The overall accuracy is 97.5%. We compare this approach to the traditional dynamic programming (DP) approach, and find that DP with slope constraints of 0 and 1 achieve 98.5% and 85% accuracies respectively. Finally we validate out statistics by training and testing the network of a four-word subset of the Texas Instruments (Tl) isolated word database. The accuracy with this vocabulary exceeds 96%. By doubling the size of the training set, the accuracy is raised to 98%. Using a suitable threshold, we are able to raise the accuracy of one network from 87% to 98.5%. Thresholding applied to all networks would then raise the overall accuracy to well over 99%.

This technique is especially promising because of the low overhead and computational requirements, which make it suitable for a low cost, portable, command recognition type of application.     

改变产妇体位矫正胎儿方位的临床效果

目的:探讨产程中改变产妇体位以矫正胎位。方法:选择临产至宫口开全经B超及内诊检查为枕后位的初产妇200例,随机分为观察组与对照组各100例,在产程中指导观察组产妇取侧俯卧位,利用胎儿重力、羊水浮力、子宫间歇性收缩的合力作用,使胎头下降时逐渐从枕后位转至枕前位娩出,并与对照组比较。结果:观察组91例(91％)胎儿由枕后位转至枕前位经阴道分娩,剖宫产9例(9％);对照组经阴道分娩仅16例(16％),剖宫产84例(84％)。两组比较差异有显著性(P<0.01)。结论:在产程中指导产妇取侧俯卧位,用以矫正胎位不正是降低难产发生率的有效方法。     

16通道人工耳蜗植入装置的原理和研制

人工耳蜗植入是利用电听觉原理恢复聋人听觉的一种有效方法，作者依据耳蜗在电刺激条件下的听觉生理学原理和心理声学参量，提出汉语主意编码方案的设想，研制出１６通道耳蜗植入电极系统和语言处理装置，并进行初步动物实验研究。     

基于永磁磁场的电子胶囊定位系统

为了确定可吞服式电子胶囊在人体内的位置,基于矩形永磁体空间磁场解析式,设计了定位系统,提出了相应的定位算法,并进行了实验。系统中两个三轴磁传感器封装在胶囊内,由胶囊和永磁体的空间位姿关系模型,建立了与传感器输出和胶囊位姿变量相关的一组非线性方程。对方程进行了数值求解,并和期望值进行了比较,结果发现该方法是切实可行的。     

Proprioception does not quickly drift during visual occlusion

Several perceptual studies have shown that the ability to estimate the location of the arm degrades quickly during visual occlusion. To account for this effect, it has been suggested that proprioception drifts when not continuously calibrated by vision. In the present study, we re-evaluated this hypothesis by isolating the proprioceptive component of position sense (i.e., the subjects were forced to rely exclusively on proprioception to locate their hand, which was not the case in earlier studies). Three experiments were conducted. In experiment 1, subjects were required to estimate the location of their unseen right hand, at rest, using a visual spot controlled by the left hand through a joystick. Results showed that the mean accuracy was identical whether the localization task was performed immediately after the positioning of the hand or after a 10-s delay. In experiments 2 and 3, subjects were required to point, without vision of their limb, to visual targets. These two experiments relied on the demonstration that biases in the perception of the initial hand location induced systematic variations of the movement characteristics (initial direction, final accuracy, end-point variability). For these motor tasks, the subjects did not pay attention to the initial hand location, which removed the possible occurrence of confounding cognitive strategies. Results indicated that movement characteristics were, on average, not affected when a 15-s or 20-s delay was introduced between the positioning of the arm at the starting point and the presentation of the target. When considered together, our results suggest that proprioception does not quickly drift in the absence of visual information. The potential origin of the discrepancy between our results and earlier studies is discussed.     

Viewer-centred and object-centred coding of heads in the macaque temporal cortex

Summary An investigation was made into the sensitivity of cells in the macaque superior temporal sulcus (STS) to the sight of different perspective views of the head. This allowed assessment of (a) whether coding was viewer-centred (view specific) or object-centred (view invariant) and (b) whether viewer-centred cells were preferentially tuned to characteristic views of the head. The majority of cells (110) were found to be viewer-centred and exhibited unimodal tuning to one view. 5 cells displayed object-centred coding responding equally to all views of the head. A further 5 cells showed mixed properties, responding to all views of the head but also discriminating between views. 6 out of 56 viewer and object-centred cells exhibited selectivity for face identity or species. Tuning to view varied in sharpness. For most (54/73) cells the angle of perspective rotation reducing response to half maximal was 45–70° but for 19/73 it was >90°. More cells were optimally tuned to characteristic views of the head (the full face or profile) than to other views. Some cells were, however, found tuned to intermediate views throughout the full 360 degree range. This coding of many distinct head views may have a role in the analysis of social signals based on the interpretation of the direction of other individuals' attention.