Feature extraction of 3D Chinese rose model based on color and shape features.

Flower classification is of great importance to the research fields of plants, food, and medicine. Due to more abundant information on three-dimensional (3D) flower models than two-dimensional 2D images, it makes the 3D models more suitable for flower classification tasks. In this study, a feature extraction and classification method were proposed based on the 3D models of Chinese roses. Firstly, the shape distribution method was used to extract the sharpness and contour features of 3D flower models, and the color features were obtained from the Red-Green-Blue (RGB) color space. Then, the RF-OOB method was employed to rank the extracted flower features. A shape descriptor based on the unique attributes of Chinese roses was constructed, χ2 distance was adopted to measure the similarity between different Chinese roses. Experimental results show that the proposed method was effective for the retrieval and classification tasks of Chinese roses, and the average classification accuracy was approximately 87%, which can meet the basic retrieval requirements of 3D flower models. The proposed method promotes the classification of Chinese roses from 2D space to 3D space, which broadens the research method of flower classification.

Epidemiological characteristics of sexually transmitted diseases from 2005 to 2017 in Mengla County， Yunnan Province / 上海预防医学

Objective:To determine the epidemiological characteristics and incidence trends of sexually transmitted diseases （STD） in Mengla County of Yunnan Province， and provide evidence for future prevention and control of STD. Methods:STD case information from 2005 to 2017 was extracted from the National Notifiable Infectious Disease Report Information System. Data were collected by year and disease type，and the incidence rate， epidemic characteristics and suspicious contact history of STD were statistically analyzed. Results:A total of 1 251 STD cases were reported in Mengla county from 2005 to 2017， including 490 gonorrhea， 483 syphilis， 216 condyloma acuminatum， 16 genital chlamydial infection and 46 genital herpes. The average annual incidence of STD was 35.57/100 000. The majority of STD cases were 20-29 years old （n=541，43.25%）， married （n=603，48.20%）， Han people （n=638，50.10%）， with education of middle school （n=536，42.85%）， and occupation of farmers （n=702， 56.12%）. The 42.61% of STD cases had non-marital sexual contact history， in which the proportion was significantly higher among male （55.05%） than female （28.98%）. In addition， the proportion of non-marital sex among STD cases increased gradually by year and significantly differed. Conclusion:The epidemic status of STD in Mengla county is relatively low. However， STD incidence increased gradually by year， which warrants more and specific measures on the STD control and prevention.

Evaluation of basic laparoscopic training under 5A teaching mode / 中华胃肠外科杂志

Objective: To evaluate the rationality and effectiveness of basic laparoscopic training under 5A teaching mode. Methods: A prospective randomized controlled study was conducted. The teaching records of 70 trainees who received basic laparoscopic traning at the Laparoscopic Surgical Training Base in Chinese PLA General Hospital from July to December 2019 were analyzed. All the trainees participating in the laparoscopy training had obtained the national practicing physician certificates, including 12 junior physicians of our center, 9 intermediate physicians of our center, 19 advanced physicians, 13 postgraduate students, 8 doctoral students, and 9 surgical standardized training physicians. A random number table method was used to divide all the trainees into two groups: the traditional teaching group or the 5A teaching group (35 people in each group). In the traditional teaching group, the training of 4 modules of " precise beans, quincuncial piles, ring positioning and knot-tying suture" modules according to a fixed sequence and schedule was carried out. Each module had a learning time of 8 hours. In the 5A teaching group, the training started from five dimensions of analysis, aim, accomplishment, appraise and advance. Before conducting each stage of training, the actual operation ability of the trainees was tested, each class hour was designed individually, accurate teaching was conducted to the trainees, the ability of the trainees was evaluated dynamically, and the previous steps were cycled periodically based on class hours. The operating time and pass rate of trainees of two groups in the basic operation module of laparoscopy were statistically analyzed, and a hierarchical analysis of related influencing factors was conducted. Results: The time of above modules before training in the 5A teaching group and the traditional teaching group was similar (all P>0.05). After definitive training, the time required for trainees in 5A teaching group and traditional teaching group to complete the 4 modules was shortened to varying degrees. Compared to traditional teaching group, 5A teaching group spent less time in completing each project [precise beans: (63.2±10.1) seconds vs. (83.6±18.7) seconds, quincuncial piles: (56.2±7.3) seconds vs. (101.4±31.7) seconds, ring positioning: (84.2±13.7) seconds vs. (127.3±28.5) seconds, knot-tying suture: (263.2±41.8) seconds vs.(428.8±95.2) seconds, all P<0.05], and had higher pass rates [precise beans: 97.1% (34/35) vs. 80.0% (28/35), quincuncial piles: 91.4% (32/35) vs.71.4% (25/35), ring positioning: 100.0% (35/35) vs. 82.9% (29/35), knot-tying suture: 77.1% (27/35) vs. 60.0% (21/35), all P<0.05]. Among the junior trainees (junior physicians of our center, postgraduate students, doctoral students, and standardized surgical training physicians) and intermediate trainees (intermediate physicians of our center and advanced physicians), the 5A teaching group completed 3 modules (quincuncial piles, ring positioning and knot-tying suture) faster than the traditional teaching group [junior trainees: quincuncial piles (76.4±12.4) seconds vs. (139.8±41.6) seconds, ring positioning (92.2±20.5) seconds vs. (131.3±28.4) seconds, knot-tying suture (293.8±66.7) seconds vs. (444.3±103.3) seconds; intermediate trainees: quincuncial piles (51.4±5.9) seconds vs. (94.7±8.6) seconds, ring positioning (63.9±13.5) seconds vs. (87.5±18.6) seconds, knot-tying suture (210.1±35.6) seconds vs. (367.5±54.9) seconds, all P<0.05]. Conclusion: 5A teaching mode can acheive better training results compared with the traditional teaching mode in basic laparoscopic training, and is worthy of further popularization and application.

HPM-based dynamic sparse grid approach for Perona-Malik equation.

The Perona-Malik equation is a famous image edge-preserved denoising model, which is represented as a nonlinear 2-dimension partial differential equation. Based on the homotopy perturbation method (HPM) and the multiscale interpolation theory, a dynamic sparse grid method for Perona-Malik was constructed in this paper. Compared with the traditional multiscale numerical techniques, the proposed method is independent of the basis function. In this method, a dynamic choice scheme of external grid points is proposed to eliminate the artifacts introduced by the partitioning technique. In order to decrease the calculation amount introduced by the change of the external grid points, the Newton interpolation technique is employed instead of the traditional Lagrange interpolation operator, and the condition number of the discretized matrix different equations is taken into account of the choice of the external grid points. Using the new numerical scheme, the time complexity of the sparse grid method for the image denoising is decreased to O(4 (J+2j)) from O(4(3J)), (j ≪ J). The experiment results show that the dynamic choice scheme of the external gird points can eliminate the boundary effect effectively and the efficiency can also be improved greatly comparing with the classical interval wavelets numerical methods.

VIM-based dynamic sparse grid approach to partial differential equations.

Combining the variational iteration method (VIM) with the sparse grid theory, a dynamic sparse grid approach for nonlinear PDEs is proposed in this paper. In this method, a multilevel interpolation operator is constructed based on the sparse grids theory firstly. The operator is based on the linear combination of the basic functions and independent of them. Second, by means of the precise integration method (PIM), the VIM is developed to solve the nonlinear system of ODEs which is obtained from the discretization of the PDEs. In addition, a dynamic choice scheme on both of the inner and external grid points is proposed. It is different from the traditional interval wavelet collocation method in which the choice of both of the inner and external grid points is dynamic. The numerical experiments show that our method is better than the traditional wavelet collocation method, especially in solving the PDEs with the Nuemann boundary conditions.