改进分形法结合局部熵的红外小目标检测方法

本文提出了一种组合分维数、截距、拟合误差3个分形特征的改进分形算法,改善了传统方法提取单一分形特征在红外小目标图像检测时不能有效区分目标和背景的不足。同时介绍了局部熵理论在目标检测方面的应用。算法首先通过计算局部熵,得到目标所在的小区域,然后利用改进分形法进行目标检测。实验证明,该方法可以有效抑制虚警,提高检测率,降低时间复杂度。     

基于隐式限制四叉树的大规模动态地形建模与仿真方法

大规模动态地形场景的建模与仿真是计算机图形学与虚拟显示领域的重要课题之一。本文提出了一种基于隐式限制四叉树的地形建模方法,用四叉树标记数组代替四叉树节点结构与指针操作,不但节省了大规模地形数据集所占的存储空间,而且提高了节点的索引效率。另外,提出了基于高程值的地形纹理图像合成方法,根据地形采样点的高程值实时合成匹配地形特征的纹理图像。本文还给出了弹坑与车辙的建模方法。仿真结果表明,本文描述的方法可以实时获得逼真的大规模动态地形仿真效果。     

一种新的基于彩色双边滤波的彩色图像增强方法

本文提出一种新的基于彩色双边滤波的彩色图像增强方法。该方法将彩色图像增强分为三部分：全局亮度调节、对比度增强和颜色恢复。全局亮度调节主要是对图像的整体亮度信息进行非线性调整,压缩图像的亮度动态范围 局部对比度增强主要是利用彩色双边滤波获得像素点所在邻域的背景亮度,由当前像素点的亮度与背景亮度之间的关系,通过非线性的方法增强图像局部对比度 最后通过颜色恢复算法恢复图像色彩。相关实验表明,本文所提方法可以获得很好的彩色图像增强效果。     

基于多特征提取的遥感图像机场目标自动检测

传统的遥感图像机场跑道自动目标检测由于仅提取灰度特征常产生过分割现象,本文采用灰度特征和纹理特征相结合的方法进一步提高跑道的检测精度。利用阈值对遥感图像进行初始分割,以定位感兴趣区域（ROI）,再利用EM算法估计ROI区域训练样本,引入马尔可夫随机场（MRF）模型,分割机场跑道。实验表明MRF可以很好地描述空间连续性,可以达到精确检测机场跑道的目的。     

基于广义霍夫变换的多目标跟踪算法

提出了一种融合局部特征匹配与概率外观模型的多目标跟踪方法。引入局部特征可以减轻外观模型跟踪算法对前景提取质量的过度依赖,并提高对目标姿态变化和遮挡情况的适应性。首先利用目标局部特征构建描述目标特征信息与空间信息的码书。然后建立基于目标全局特征的颜色与概率外观模型。最后经过广义霍夫变换迭代过程预测目标的可能位置。实验结果表明,本文算法能在目标姿态变化、严重遮挡等情况下,取得可靠而高效的跟踪效果。     

基于变换域特征的星空背景弱小目标检测算法

针对CCD光电序列探测图像中的弱小运动目标检测问题,提出了一种运动星空背景下的基于变换域特征的弱小目标检测算法。在变换域中以星点到参考恒星的变化距离为特征信息,根据恒星和目标的运动特性构建的相似性度量函数进行潜在目标点划分,通过轨迹关联最终完成弱小目标的检测。实验结果表明,该算法充分考虑了恒星、目标和噪声的灰度和运动特性,能有效的实现运动星空背景下的弱小目标检测。     

变背景下红外目标的跟踪

采用粒子滤波跟踪变背景下红外目标时,粒子的规模和模板的更新方法对粒子滤波是非常重要的,针对上述问题本文提出了一种基于动态粒子和自适应多模板更新策略的粒子滤波方法,首先通过动态去除权值较小的粒子,不仅防止了粒子的退化,而且提高了算法性能,其次,算法保留两个模板,动态保留下的粒子与两个模板同时比较,对匹配程度最大的模板进行更新,这样可以有效降低跟丢率。最后我们采用红外飞机目标视频检验本文算法,实验结果表明在变背景下,本文算法有效而可靠。     

基于Laws能量和变化频次的伪装色移动目标检测

动态背景下的移动目标检测是视频监控的研究热点之一,具有伪装色的移动目标检测是其中的一个难点.传统的高斯混合模型不适合检测这类移动目标.通过分析动态背景下具有伪装色移动目标的颜色变化规律,提出了利用Laws能量和一种称为变化频次的特殊统计量的检测方法.实验表明,该方法能够有效地检测某些动态背景下一些具有伪装色的移动目标,...     

车辆排队长度自动检测新方法

目的提出一种基于图像处理的车辆排队长度自动检测方法。方法首先,提出基于固定背景区域窗口最大相似度配准法来校正实时采集图像因抖动的干扰所引起车道区域的偏差;接着,将交通图像转换为简约纹理单元的纹理图像,突出有车辆车道与空车道的纹理差异,结合最大方差阈值分割算法,分离出车辆与空车道;最后,实现一个基于队尾空车道区域特征的排队长度自动检测算法。结果实现了车辆排队长度的自动检测。结论试验结果说明该方法具有较理想检测效果,能有效地克服抖动与光照干扰。     

基于纹理特征的SAR图像水上桥梁目标检测

针对SAR影像进行水上桥梁目标检测问题,提出了一种纹理特征与关联特征相结合的方法。该方法首先通过去噪及增强预处理改善图像质量,并采用阈值分割方法快速提取初始目标;然后使用灰度共生矩阵对目标及其周边背景纹理进行差异对比分析,从而去除虚警目标。实验结果表明,该方法能够准确地检测出水上桥梁目标。     

Predicting US- and state-level cancer counts for the current calendar year: Part II: evaluation of spatiotemporal projection methods for incidence

BACKGROUND.

The current study was undertaken to evaluate the spatiotemporal projection models applied by the American Cancer Society to predict the number of new cancer cases.

METHODS.

Adaptations of a model that has been used since 2007 were evaluated. Modeling is conducted in 3 steps. In step I, ecologic predictors of spatiotemporal variation are used to estimate age‐specific incidence counts for every county in the country, providing an estimate even in those areas that are missing data for specific years. Step II adjusts the step I estimates for reporting delays. In step III, the delay‐adjusted predictions are projected 4 years ahead to the current calendar year. Adaptations of the original model include updating covariates and evaluating alternative projection methods. Residual analysis and evaluation of 5 temporal projection methods were conducted.

RESULTS.

The differences between the spatiotemporal model‐estimated case counts and the observed case counts for 2007 were < 1%. After delays in reporting of cases were considered, the difference was 2.5% for women and 3.3% for men. Residual analysis indicated no significant pattern that suggested the need for additional covariates. The vector autoregressive model was identified as the best temporal projection method.

CONCLUSIONS.

The current spatiotemporal prediction model is adequate to provide reasonable estimates of case counts. To project the estimated case counts ahead 4 years, the vector autoregressive model is recommended to be the best temporal projection method for producing estimates closest to the observed case counts. Cancer 2012;. © 2012 American Cancer Society.     

How to analyse the spatiotemporal tumour samples needed to investigate cancer evolution: A case study using paired primary and recurrent glioblastoma

Many traits of cancer progression (e.g., development of metastases or resistance to therapy) are facilitated by tumour evolution: Darwinian selection of subclones with distinct genotypes or phenotypes that enable such progression. Characterising these subclones provide an opportunity to develop drugs to better target their specific properties but requires the accurate identification of somatic mutations shared across multiple spatiotemporal tumours from the same patient. Current best practices for calling somatic mutations are optimised for single samples, and risk being too conservative to identify shared mutations with low prevalence in some samples. We reasoned that datasets from multiple matched tumours can be used for mutual validation and thus propose an adapted two‐stage approach: (1) low‐stringency mutation calling to identify mutations shared across samples irrespective of the weight of evidence in a single sample; (2) high‐stringency mutation calling to further characterise mutations present in a single sample. We applied our approach to three‐independent cohorts of paired primary and recurrent glioblastoma tumours, two of which have previously been analysed using existing approaches, and found that it significantly increased the amount of biologically relevant shared somatic mutations identified. We also found that duplicate removal was detrimental when identifying shared somatic mutations. Our approach is also applicable when multiple datasets e.g. DNA and RNA are available for the same tumour.     

Multi-level influence of school norms on tobacco use in South Africa: an ecometric consideration of group differences

Objectives

Tobacco use has been found to be related to contextual–environmental characteristics. This study focuses on the influence of contextual norms on adolescent smoking behavior with consideration of racial differences.

Methods

Data for this study were derived from the South African Community Epidemiology Network on Drug Use survey. Students (n = 1,277) completed a self-administered questionnaire (available in Afrikaans, Xhosa, and English). School-level aggregate measures were developed from the items: whether they thought smoking was wrong, whether they thought they would be seen as “cool” if they smoked, how many of their closest friends smoked, and whether they had repeated a grade level in school.

Results

The results of this analysis revealed that after controlling for demographic characteristics, aggregate measures of importance for ever smoking were whether there were school norms of perceiving that smoking was not wrong, perceiving that smoking was cool, and high prevalence of having friends who smoke. Recent smoking was only predicted by attendance at schools with increased levels of academic failure. Black South Africans were less likely to ever smoke than Coloured or White.

Conclusions

This study highlights the saliency of both compositional (academic failure) and ecological (collective perceptions about smoking) characteristics in predicting ever and recent smoking. Collective perceptions of smoking in a predominantly Black school were largely negative. These findings can be used to target school norms regarding tobacco use in Cape Town.

     

Tumour-targeted delivery of TRAIL using Salmonella typhimurium enhances breast cancer survival in mice

Background:

An effective cancer therapeutic must selectively target tumours with minimal systemic toxicity. Expression of a cytotoxic protein using Salmonella typhimurium would enable spatial and temporal control of delivery because these bacteria preferentially target tumours over normal tissue.

Methods:

We engineered non-pathogenic S. typhimurium to secrete murine TNF-related apoptosis-inducing ligand (TRAIL) under the control of the prokaryotic radiation-inducible RecA promoter. The response of the RecA promoter to radiation was measured using fluorometry and immunoblotting. TRAIL toxicity was determined using flow cytometry and by measuring caspase-3 activation. A syngeneic murine tumour model was used to determine bacterial accumulation and the response to expressed TRAIL.

Results:

After irradiation, engineered S. typhimurium secreted TRAIL, which caused caspase-3-mediated apoptosis and death in 4T1 mammary carcinoma cells in culture. Systemic injection of Salmonella and induction of TRAIL expression using 2 Gy γ-irradiation caused a significant delay in mammary tumour growth and reduced the risk of death by 76% when compared with irradiated controls. Repeated dosing with TRAIL-bearing Salmonella in conjunction with radiation improved the 30-day survival from 0 to 100%.

Conclusion:

These results show the pre-clinical utility of S. typhimurium as a TRAIL expression vector that effectively reduces tumour growth and extends host survival.     

Measuring radiation fibrosis: the interobserver reliability of two methods of determining the degree of radiation fibrosis

Purpose: To compare the interobserver reliability of the palpation method with the method of measuring tissue compliance with a tissue compliance meter (TCM) on women who underwent breast-conserving surgery and radiotherapy for breast cancer.

Methods and Materials: Thirty-eight patients and 30 controls were measured with the palpation method by two radiation oncologists and with the TCM by two physiotherapists. Measurements were taken on four locations of the breasts of all 68 women. Reliability coefficients were computed for both methods. A weighted kappa score was computed for the palpation method and this was compared with the intraclass correlation coefficient (ICC) computed for the TCM method. The conditions for direct comparison of these scores were met in this study.

Results: A weighted kappa of 0.65 was computed for the palpation method and an ICC of 0.91 was computed for the TCM method. These scores differ significantly from each other (p < 0.01).

Conclusion: The interobserver reliability of the TCM method is superior to that of the palpation method. However, at locations where the TCM is not applicable, palpation is a good alternative.     

一种免疫细胞图像非监督分割方法

对免疫细胞图像进行全自动分析在医学疾病诊断上有很高的应用价值。要完成自动图像分析,关键是要实现图像的非监督分割。根据免疫细胞图像中细胞核是一种椭圆状目标的特点,提出了一种椭圆形目标定位方法。在文献中,首先用这种目标定位方法将待分割图像中的细胞核位置找到,然后在细胞核所在的区域内运行水域分割算法(watershed变换)就可实现图像的非监督分割。这种非监督分割策略解决了在大范围内运行中算法一次分割目标时存在的容易错分割的缺点,实现了对特定细胞图像的非监督分割。实验结果表明该方法具有目标定位准确率较高、分割的准确精度和可重复性好等特点。     

Limitation of immunohistochemical localization of estrogen receptor

Although the radioreceptor method is widely used for estrogen receptor assay in human tissue, it has several limitations and a number of alternative methods are being explored. An immunohistochemical method of estrogen receptor assay using a specific antibody to estradiol has been proposed as a suitable alternative. The present study was designed to evaluate the validity of this method in detecting true estrogen receptors in human tumor tissue. Using radioiodinated antibody to estrogen, we have demonstrated that the estrogen antibody can detect the estrogen when it is bound to 4S type receptor but is unable to bind to estrogen when the hormone is bound to 8S type receptor. Our observations suggest that the immunohistochemical method of detection of intracellular cytosolic receptor for estrogen is not a suitable alternative to the currently used radioreceptor method.     

Sentinel lymph node biopsy using tin colloid Rl and blue dye method

Axillary dissection has been considered essential for breast cancer staging because nodal metastasis is the most powerful predictive factor for recurrence. On the other hand, morbidity, such as lymphedema and shoulder dysfunction, may occur. Sentinel node biopsy is a good way to avoid unnecessary axillary dissection. We used tin colloid as a carrier of Tc99m tracer together with the blue dye method. The detection rate of the sentinel node was 27 cases out of 29 (90%) for the blue dye method, 10 cases out of 19 (53%) for the RI method, and 27 out of 33 (82%) for the combined method. The detection rate of the RI method was improved after adding the subcutaneous injection over the tumor from 45% before adding the subcutaneous injection to 82% after adding it. The false negative rate was 11% for the blue dye method, 0% for the RI method, and 10% for the combined method. This yields a sensitivity of 89% for the blue dye method, 100% for the RI method, and 90% for the combined method. Specificity was 100% for all three methods. Accuracy was 96% for the blue dye method, 100% for the RI method, and 96% for the combined method. There were two false negative cases. The average number of sentinel lymph nodes was 2.12 for the dye method, 1.66 for the RI method, and 1.95 for the combined method. There were three of 49 cases with identified parasternal lymph nodes by RI imaging. Lymphatic mapping using tin colloid may be useful for detecting sentinel nodes.     

基于小波域分块和码率分配的高分辨率图像低复杂度压缩方法

本文提出了一种适于高分辨率图像的低复杂度图像压缩方法,高分辨率图像小波变换后在小波域进行分块,然后采用EBCOT方法并行压缩,对各分块图像根据纹理复杂度分配码率,解决了采用传统图像域分块方法造成的图像不同区域由于复杂性差异较大而引起的简单部分恢复质量很好,而复杂度高的部分恢复质量差甚至不可用的问题,同时避免了图像域分块引起的“方块效应”。实验结果表明,本文算法重建效果十分接近全局压缩效果,尤其适合各区域复杂度差异很大的遥感图像 算法复杂度低,易于硬件实现,适于遥感图像的星载实时压缩。     

A new method to obtain transmission images for planar whole-body activity quantification

Dosimetry is important in the evaluation of new radiopharmaceuticals and in radionuclide therapy treatment planning. The base is an accurate in vivo measurement of the spatial and temporal distribution of the administered radioactivity. This can be made by planar whole-body activity quantification using the conjugate-view method where a geometrical-mean image is corrected for attenuation by a measured transmission image. We present a new method to measure whole-body transmission images using the X-ray unit on a single photon emission computed tomography/computed tomography (SPECT/CT) scintillation system. METHOD: Two general problems are associated with this method: (1) the divergence of the X-ray beam and (2) the scaling of the resulting image. We have applied linear transformations and scale by a system-generated factor to obtain images corresponding to a radiological depth at 70 keV. We validated the method by measurements of the radiological depth for different types of phantoms, and in terms of activity quantification accuracy when applying the method for attenuation correction. RESULTS: An accuracy of within +/-4% was found for both the radiological depth measurements and for the activity-quantification measurements. CONCLUSIONS: The advantage with the proposed method is that it is fast (2 minutes for a 2-minute scan), it has good spatial resolution and signal-to-noise ratio, and it is easy to carry out for the patient.