城乡二元户籍制度下的我国劳动力市场分析

分析户口迁移政策改革的成本与收益 ,对我国劳动力市场跨地区流动进行了实证分析 ,认为实现劳动力的自由迁移不仅符合政府部门的利益而且可以减少城乡收入差距 ,实现政府的目标     

A comprehensive non‐invasive framework for automated evaluation of acute renal transplant rejection using DCE‐MRI

The objective was to develop a novel and automated comprehensive framework for the non‐invasive identification and classification of kidney non‐rejection and acute rejection transplants using 2D dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI). The proposed approach consists of four steps. First, kidney objects are segmented from the surrounding structures with a geometric deformable model. Second, a non‐rigid registration approach is employed to account for any local kidney deformation. In the third step, the cortex of the kidney is extracted in order to determine dynamic agent delivery, since it is the cortex that is primarily affected by the perfusion deficits that underlie the pathophysiology of acute rejection. Finally, we use an analytical function‐based model to fit the dynamic contrast agent kinetic curves in order to determine possible rejection candidates. Five features that map the data from the original data space to the feature space are chosen with a k‐nearest‐neighbor (KNN) classifier to distinguish between acute rejection and non‐rejection transplants. Our study includes 50 transplant patients divided into two groups: 27 patients with stable kidney function and the remainder with impaired kidney function. All of the patients underwent DCE‐MRI, while the patients in the impaired group also underwent ultrasound‐guided fine needle biopsy. We extracted the kidney objects and the renal cortex from DCE‐MRI for accurate medical evaluation with an accuracy of 0.97 ± 0.02 and 0.90 ± 0.03, respectively, using the Dice similarity metric. In a cohort of 50 participants, our framework classified all cases correctly (100%) as rejection or non‐rejection transplant candidates, which is comparable to the gold standard of biopsy but without the associated deleterious side‐effects. Both the 95% confidence interval (CI) statistic and the receiver operating characteristic (ROC) analysis document the ability to separate rejection and non‐rejection groups. The average plateau (AP) signal magnitude and the gamma‐variate model functional parameter α have the best individual discriminating characteristics. Copyright © 2013 John Wiley & Sons, Ltd.     

Joint Segmentation and Groupwise Registration of Cardiac Perfusion Images Using Temporal Information

We propose a joint segmentation and groupwise registration method for dynamic cardiac perfusion images that uses temporal information. The nature of perfusion images makes groupwise registration especially attractive as the temporal information from the entire image sequence can be used. Registration aims to maximize the smoothness of the intensity signal while segmentation minimizes a pixel’s dissimilarity with other pixels having the same segmentation label. The cost function is optimized in an iterative fashion using B-splines. Tests on real patient datasets show that compared with two other methods, our method shows lower registration error and higher segmentation accuracy. This is attributed to the use of temporal information for groupwise registration and mutual complementary registration and segmentation information in one framework while other methods solve the two problems separately.     

In-vivo stretch of term human fetal membranes

IntroductionFetal membranes (FM) usually fail prior to delivery during term labor, but occasionally fail at preterm gestation, precipitating preterm birth. To understand the FM biomechanical properties underlying these events, study of the baseline in-vivo stretch experienced by the FM is required. This study's objective was to utilize high resolution MRI imaging to determine in-vivo FM stretch.MethodsEight pregnant women (38.4 ± 0.4wks) underwent abdominal-pelvic MRI prior to (2.88 ± 0.83d) caesarean delivery. Software was utilized to determine the total FM in-vivo surface area (SA) and that of its components: placental disc and reflected FM. At delivery, the SA of the disc and FM in the relaxed state were measured. In-vivo (stretched) to delivered SA ratios were calculated. FM fragments were then biaxially stretched to determine the force required to re-stretch the FM back to in-vivo SA.ResultsTotal FM SA, in-vivo vs delivered, was 2135.51 ± 108.47 cm² vs 842.59 ± 35.86 cm²; reflected FM was 1778.42 ± 107.39 cm² vs 545.41 ± 22.90 cm², and disc was 357.10 ± 28.08 cm² vs 297.18 ± 22.14 cm². The ratio (in-vivo to in-vitro SA) of reflected FM was 3.26 ± 0.11 and disc was 1.22 ± 0.10. Reflected FM re-stretched to in-vivo SA generated a tension of 72.26 N/m, corresponding to approximate pressure of 15.4 mmHg. FM rupture occurred at 295.08 ± 31.73 N/m corresponding to approximate pressure of 34 mmHg. Physiological SA was 70% of that at rupture.DiscussionFM are significantly distended in-vivo. FM collagen fibers were rapidly recruited once loaded and functioned near the failure state during in-vitro testing, suggesting that, in-vivo, minimal additional (beyond physiological) stretch may facilitate rapid, catastrophic failure.     

Evidence of favorable sleep-EEG patterns in adolescent male vigorous football players compared to controls

Sleep is crucial for psychological functioning and daily performance. Both lay and scientific opinion hold that physical activity encourages restorative sleep. However, research on this in adolescence is limited. The aim of the present study was to compare sleep-EEG patterns of vigorous exercisers and controls. Twelve adolescent male football players (14 h of vigorous exercise per week) and 12 controls (1.5 h of vigorous exercise per week) matched for gender, age (about 16 years), and educational level, took part in the study. Sleep-EEG registration was performed following a day without exercise. Sleep-EEG analyses revealed that, compared to controls, the football players showed greater sleep efficiency, shortened sleep onset latency, less awakenings after sleep onset, more stage 4, and less REM sleep. Importantly, this pattern of results emerged following a day without exercise. Moreover, vigorous football players reported better daily performance and displayed less weeknight (Sunday to Thursday) to weekend night (Friday and Saturday nights) variation. Findings suggest that for the football players, vigorous exercise seemed to lead to longer-lasting electrophysiological change in brain activity irrespective of acute bouts of exercise.     

Validation of a semi‐automatic co‐registration of MRI scans in patients with brain tumors during treatment follow‐up

There is an expanding research interest in high‐grade gliomas because of their significant population burden and poor survival despite the extensive standard multimodal treatment. One of the obstacles is the lack of individualized monitoring of tumor characteristics and treatment response before, during and after treatment. We have developed a two‐stage semi‐automatic method to co‐register MRI scans at different time points before and after surgical and adjuvant treatment of high‐grade gliomas. This two‐stage co‐registration includes a linear co‐registration of the semi‐automatically derived mask of the preoperative contrast‐enhancing area or postoperative resection cavity, brain contour and ventricles between different time points. The resulting transformation matrix was then applied in a non‐linear manner to co‐register conventional contrast‐enhanced T₁‐weighted images. Targeted registration errors were calculated and compared with linear and non‐linear co‐registered images. Targeted registration errors were smaller for the semi‐automatic non‐linear co‐registration compared with both the non‐linear and linear co‐registered images. This was further visualized using a three‐dimensional structural similarity method. The semi‐automatic non‐linear co‐registration allowed for optimal correction of the variable brain shift at different time points as evaluated by the minimal targeted registration error. This proposed method allows for the accurate evaluation of the treatment response, essential for the growing research area of brain tumor imaging and treatment response evaluation in large sets of patients. Copyright © 2016 John Wiley & Sons, Ltd.     

探析药品注册管理课堂教学内容与方法有机融合

目的：以人民卫生出版社出版的《药事管理学》6版教材为蓝本，以本科阶段教学效果提高为指标，探讨改进课堂教学的方法。方法：以"药品注册管理"一章教学内容为例，筛选、调整和优化教学方法。结果：教学过程中，按照教学内容特点选择适宜教学方法，确定"教学方法与内容相融合"的课堂教学模式，在完成教学大纲基础上，适当增加执业药师及药学时事相关内容。结论：根据现代学生获取知识途径，充分利用高新技术背景下"智慧教室"资源，采取传统与现代教学方法相结合的教学模式，使课堂理论教学相关内容在以教材内容为主的前提下与国家当前药事时事相关联，可以增加学生课堂学习兴趣、培养自主学习习惯，从而提高教师教学能力和教学质量，实现培养具备专业知识、技能和法律、道德素养的药学应用型综合人才的预期目标。     

Normalized gradient fields for nonlinear motion correction of DCE-MRI time series

Dynamic MR image recordings (DCE-MRI) of moving organs using bolus injections create two different types of dynamics in the images: (i) spatial motion artifacts due to patient movements, breathing and physiological pulsations that we want to counteract and (ii) signal intensity changes during contrast agent wash-in and wash-out that we want to preserve. Proper image registration is needed to counteract the motion artifacts and for a reliable assessment of physiological parameters. In this work we present a partial differential equation-based method for deformable multimodal image registration using normalized gradients and the Fourier transform to solve the Euler–Lagrange equations in a multilevel hierarchy. This approach is particularly well suited to handle the motion challenges in DCE-MRI time series, being validated on ten DCE-MRI datasets from the moving kidney. We found that both normalized gradients and mutual information work as high-performing cost functionals for motion correction of this type of data. Furthermore, we demonstrated that normalized gradients have improved performance compared to mutual information as assessed by several performance measures. We conclude that normalized gradients can be a viable alternative to mutual information regarding registration accuracy, and with promising clinical applications to DCE-MRI recordings from moving organs.     

Centralized Registration,Prophylactic Examination,and Treatment Results in Improved Prognosis in Familial Adenomatous Polyposis: Results from the Danish Polyposis Register

Background: Over the last few decades numerous regional and national registers have been established all over the world with the aim of improving survival in familial adenomatous polyposis (FAP). The Danish Polyposis Register was founded in 1971 and coordinates the screening and subsequent prophylactic colectomy of FAP patients. Methods: The crude cumulative survival in 321 patients (205 probands and 116 call-up cases) with verified FAP was calculated in accordance with the life-table method. Results: At the time of diagnosis of FAP only 2 of 116 (2%) had colorectal cancer versus 142 of 205 probands (69%). The 10-year cumulative survival was 94% (95% confidence limits, 89-99) in call-up cases compared with only 41% (34-49) in probands (p < 0.00001), and survival improved significantly (p < 0.00001) after the establishment of the Danish Polyposis Register. Conclusion: The establishment of a centralized polyposis register has resulted in a substantial improvement of the prognosis in FAP.