How to improve microscopic images obtained with consumer-type digital cameras

AIM: Digital imaging is useful in conventional photography because it immediately provides images, and the image quality can be improved afterwards by the use of computer programs. The major disadvantages of consumer-type digital cameras mounted on microscopes are (i) unequal illumination through the image, and (ii) a coloured background. A computer program was specifically adapted and refined to improve images obtained with consumer-type digital cameras mounted on microscopes. METHODS AND RESULTS: An approach using a division operation between the specimen image and a background image leads to homogeneous illumination throughout the image, with automatically corrected brightness and white background. The correct colour spectrum is preserved by correction of the histogram. This approach was obtained from the freeware computer program 'Image Arithmetic'. In a test, three different consumer-type digital cameras (Sony, Nikon, Olympus) on different microscopes were used to obtain images of different types of histological specimens (cervical smear, bone marrow biopsy, and colonic biopsy). The computer program dramatically improved the quality of images obtained with all tested cameras. CONCLUSION: Using this approach, even low-cost digital cameras mounted on microscopes produce brilliant images with homogeneous illumination and a white background, the image quality being comparable with expensive cameras especially designed for microscopes.     

Perceptual Speed and IQ Are Associated Through Common Genetic Factors

Individual differences in inspection time explain about 20% of IQ test variance. To determine whether the association between inspection time and IQ is mediated by common genes or by a common environmental factor, inspection time and IQ were assessed in an extended twin design. Data from 688 participants from 271 families were collected as part of a large ongoing project on the genetics of adult brain function and cognition. The sample consisted of a young adult cohort (mean age 26.2 years) and an older adult cohort (mean age 50.4 years). IQ was assessed with the Dutch version of the WAIS-3R. Inspection time was measured in the so-called -paradigm, in which a subject is asked to decide which leg of the -figure is longest at varying display times of the -figure. The number of correct inspections per second (i.e., the reciprocal of inspection time) was used to index perceptual speed. For Verbal IQ and Performance IQ, heritabilities were 85% and 69%, respectively. For perceptual speed, 46% of the total variance was explained by genetic variance. No differences in heritability estimates across age cohorts or sexes were found. Across the whole sample, a significant phenotypic correlation was found between perceptual speed and Verbal IQ (0.19) and between perceptual speed and Performance IQ (0.27). These correlations were entirely due to a common genetic factor that accounted for 10% of the genetic variance in verbal IQ and for 22% of the genetic variance in performance IQ. This factor is hypothesized to reflect the influence of genetic factors that determine axonal myelination in the central nervous system.     

管道骨骼线三维重建在肝脏可视化的应用

目的 研究三维重建数字化虚拟肝脏的方法.方法 将肝脏管道灌注后的肝脏标本进行螺旋CT扫描,获取CT扫描连续图像数据集.然后使用面绘制移动立方体(MC)算法重建肝脏及其内部管道结构表面模型,并对模型进行平滑和简化.确定出管道树上的关键节点,并使用改进的种子生长法生成管道树.将生成管道的表面模型和管道树相结合实现交互式分析.结果 肝脏管道灌注和铸型良好,螺旋CT扫描获取连续肝脏断面图像数据集242张.基于骨骼线提取的肝脏管道结构三维重建肝脏模型形态逼真,交互性强,通过设定各结构的透明度和颜色能单独或组合显示肝脏、肝静脉和下腔静脉、门静脉、胆囊,并可通过旋转、放大、缩小模型观察各结构.结论 基于肝脏管道骨骼线的方法进行肝脏及其管道系统三维重建可视化肝脏,生成肝脏和内部管道系统,立体空间感强,交互性好.     

Firing of inferior colliculus neurons in response to low-frequency sound stimulation during sleep and waking

SUMMARY  In vivo extracellular recordings of 102 units in the central nucleus of the inferior colliculus (IC), were made in chronically implanted guinea-pigs during the sleep/wake cycle. During wakefulness, the units were classified according to their response characteristics. Most neurons (63%) recorded showed changes, increasing or decreasing in the number of evoked discharges during the animal's transitions between wakefulness and slow-wave sleep. In the paradoxical sleep phase, the result was similar; changes were observed in most neurons, while only 11% of units did not shift their discharge pattern during ipsilateral sound stimulation.
The post-stimulus time histogram of the overall evoked pattern of discharge showed sleep/wake dependency, i.e. changed in 35% of the units recorded during the 50 ms of sound stimulation.
Fifty-five percent of auditory neurons did not show any change in the spontaneous firing rate during slow-wave sleep as compared to the previous waking period, while 22% exhibited a discharge increase and 23% decreased their firing. During paradoxical sleep, 14 out of 17 cells increased their spontaneous firing rate. The IC auditory neurons send descending connections to regions such as the dorsal pontine nuclei, known to mediate sleep processes. Thus, for constant auditory input, the firing rate or number of discharge variations are due to functional shifts in the sleeping brain. Auditory processing is present during sleep and differs from that observed during wakefulness. Differences were observed in the evoked firing number and/or spontaneous rate, as well as in the pattern of discharge. The ultimate reason for auditory unit shifts during sleep remains yet unexplained.     

Control strategies in directing the hand to moving targets

Summary We have evaluated the use of visual information about the movement of a target in two tasks tracking and interceptions — involving multi-joint reaching movements with the arm. Target velocity was either varied in a pseudorandom order (random condition) or was kept constant (predictable condition) across trials. Response latency decreased as target velocity increased in each condition. A simple model that assumes that latency is the sum of two components — the time taken for target motion to be detected, and a fixed processing time — provides a good fit to the data. Results from a step-ramp experiment, in which the target stepped a small distance immediately preceding the onset of the ramp motion, were consistent with this model. The characteristics of the first 100 ms of the response depended on the amount of information about target motion available to the subject. In the tracking task with randomly varied target velocities, the initial changes in hand velocity were largely independent of target velocity. In contrast, when the velocity was predictable the initial hand velocity depended on target velocity. Analogously, the initial changes in the direction of hand motion in the interception task were independent of target velocity in the random condition, but depended on target velocity in the predictable condition. The time course for development of response dependence was estimated by controlling the amount of visual information about target velocity available to the subject before the onset of limb movement. The results suggest that when target velocity was random, hand movement started before visual motion processing was complete. The response was subsequently adjusted after target velocity was computed. Subjects displayed idiosyncratic strategies during the catch-up phase in the tracking task. The peak hand velocity depended on target velocity and was similar for all subjects. The time at which the peak occurred, in contrast, varied substantially among subjects. In the interception task the hand paths were straighter in the predictable than in the random condition. This appeared to be the result of making adjustments in movement direction in the former condition to correct for initially inappropriate responses.     

Processing of Norwalk virus nonstructural proteins by a 3C-like cysteine proteinase

Expression of Norwalk virus nonstructural polyprotein precursor in vitro resulted in rapid cotranslational cleavage at specific sites. The cleavage products were similar to those previously identified for Southampton virus, a highly related virus. We inactivated the virally encoded proteinase responsible for cleavage of the nonstructural polyprotein by mutation of the putative catalytic cysteine residue, which resulted in production of full-length polyprotein precursor. NV proteinase was expressed in Escherichia coli as a glutathione S-transferase fusion and purified by GST-affinity chromatography. Activity of the purified proteinase was demonstrated by incubation with the full-length precursor protein. trans cleavage of the nonstructural protein precursor resulted in cleavage products similar to those observed during cotranslational cleavage, however, at lesser efficiency. NV proteinase displayed sensitivities to cysteine and serine protease inhibitors similar to poliovirus 3C proteinase, suggesting that NV proteinase is a member of the viral cysteine proteinase family. We propose that the proteinase may play a regulatory role in viral replication.     

Cephalometric image analysis and measurement for orthognathic surgery

Automatic identification of landmarks in cephalometry is very important and useful for orthognathic surgery. A computerised automatic cephalometric analysis system (CACAS), based on image processing, is presented. For an original X-ray image, median filtering and histogram equalisation are used to improve image quality. The edge of an X-ray image is detected by a wavelet transform and Canny filter. Seventeen landmarks in cephalometry are successfully identified by knowledge-based edge tracing and changeable templates. Seventy-three measurements based on distances, angles and ratios between landmarks are computed automatically. The reliability of the landmarks and the validity of the measurements are compared for automatic and manual operation. The values of measurements obtained by CACAS are more precise and reliable: the mean error for linear measurements is less than 0.9 mm; the mean error for angular measurements is less than 1.2°. The rate of validity is over 80%, even if the image quality is poor. For an image with a high signal-to-noise ratio, the rate of validity of landmarking and measurements using the CACAS system is over 90%.     

Estimation of bladder wall location in ultrasound images

A method of automatically estimating the location of the bladder wall in ultrasound images is proposed. Obtaining this estimate is intended to be the first stage in the development of an automatic bladder volume calculation system. The first step in the bladder wall estimation scheme involves globally processing the images using standard image processing techniques to highlight the bladder wall. Separate processing sequences are required to highlight the anterior bladder wall and the posterior bladder wall. The sequence to highlight the anterior bladder wall involves Gaussian smoothing and second differencing followed by zero-crossing detection. Median filtering followed by thresholding and gradient detection is used to highlight as much of the rest of the bladder wall as was visible in the original images. Then a ‘bladder wall follower’—a line follower with rules based on the characteristics of ultrasound imaging and the anatomy involved—is applied to the processed images to estimate the bladder wall location by following the portions of the bladder wall which are highlighted and filling in the missing segments. The results achieved using this scheme are presented.     

Computerized Cardiovascular Monitoring: Method and Data

This paper describes the development of a digitized, real-time, microcomputer-based signal processing system which records the following variables: systolic and diastolic blood pressure, heart rate, pulse transit time, blood volume pulse, and R-, S-, and T-wave amplitudes of EKG signals. Forty-eight healthy subjects participated in a three-task stress response study in order to gather initial data for evaluating the reliability and validity of this monitoring system. The three tasks represented replications of earlier studies: 1) reading aloud of a monotonous neutral text (Reading Only, RO); 2) mental arithmetic without vocalization (Arithmetic Quiet, AQ); and 3) mental arithmetic with vocalization (Arithmetic Aloud, AA). The findings provided support for the reliability and validity of the new monitoring system given that few data were lost, and resting values as well as differential task responses were found to be comparable with earlier data sets derived via similar experimental protocols.