Objective:To compare the prediction efficiency of traditional linear regression model and four machine learning models on the learning behavior of clinical medical postgraduates, and to explore the pros and cons and applicability of different prediction models.Methods:A total of 6,922 clinical medical postgraduates were surveyed, their comprehensive learning behavior scores were obtained through the learning behavior scale. In the training set, Lasso linear regression and artificial neural network, decision tree, Bootstrap random forest, and lifting tree were used to build prediction models respectively. The above models were used to predict the validation set data and compare the prediction efficiency.Results:The comprehensive learning behavior score of clinical medical postgraduates was (3.31±0.54) points, and the overall compliance rate was 74.02%. In the linear regression model, the influence of age, school level, degree type, learning interest, pressure and satisfaction on learning behavior were statistically significant. In the prediction of validation set, the sensitivity, specificity, and accuracy of the linear regression model were 0.484, 0.914, and 0.801, respectively. The indexes of the four machine learning models were higher than those of the traditional linear regression model, and the Bootstrap random forest had the highest elevation.Conclusion:The linear regression model has a good prediction effect on learning behavior, and machine learning is superior to linear regression model in terms of accuracy of prediction. However, traditional linear regression models are superior to machine learning models in computational efficiency and interpretability.

Objective To detect the spatial distribution characteristics of water fluoride in Shandong Province.Methods The county-based study set Shandong Province as a research site.The county level fluoride database was matched with electronic maps to build geographic information system (GIS) spatial data platform.Global Moran's I and Local Moran's I index were calculated,respectively,and the cluster range of water fluoride distribution in Shandong Province was studied through SaTScan software.Results The water fluoride was normal (≤ 1.0 mg/L) in 54 counties in Shandong Province,mainly located in Weihai and Yantai in the eastern,Dongying in northern,and vast region in middle and southeastern of Shandong Province.Eighty-six counties were high water fluoride counties (＞ 1.0 mg/L),mainly distributed in the southwest,northwest and north-central of Shandong Province,showing a significant geographical feature.Global spatial autocorrelation analysis showed that the distribution of water fluoride content in Shandong Province showed significant positive spatial autocorrelation (Moran's I =0.44,Z =6.83,P ＜ 0.01).Local Moran's I analysis showed water fluoride in 13 counties had local spatial autocorrelation,being all high-high clusters.And these results were statistically significant (P ＜ 0.05).A cluster area was detected through SaTScan spatial analysis software,including 15 counties.The center was located in Dongming County of Heze City,with radius of 130.08 km.The results and the local spatial autocorrelation results were basically consistent.Conclusions There are apparent spatial autocorrelation and spatial cluster in water fluoridation in Shandong Province.Spatial autocorrelation and SaTScan software can be combined in exploring the spatial distribution of water fluoride.

Objective To investigate the current prevalent status of endemic fluorosis in the alluvial plain area of the Yellow River in Shandong Province,in order to provide a scientific basis for developing control measures against the disease.Methods Six counties were selected as survey counties by random sampling,ten improvedwater projects were selected in each survey county,for the projects,the operating effect was investigated and water fluoride content was tested;three epidemic villages were chosen as survey villages in each county,the operating condition and the fluoride level of water were investigated in the villages with water improvement projects.Dental fluorosis of children aged 8 to 12 was surveyed,the urinary fluoride and skeletal fluorosis X-ray diagnosis were checked of adults over the age of 25.Water fluoride and urinary fluoride contents were detected via the F-ion selective electrode method,and the prevalence of dental fluorosis of all children aged 8 to 12 was diagnosed based on Clinical Diagnostic Criteria of Dental Fluorosis (WS/T 208-2011),skeletal fluorosis X-ray diagnosis was done based on the National Standard for Diagnosis of Endemic Skeletal Fluorosis (WS 192-2008).Results ①In the six counties,58 improved-water defluoridation projects were investigated,all projects were operated normally,the qualified rate of water fluoride content was 44.83％ (26/58).②A total of 19 villages that had water-improving and defluoridation projects were investigated,and all projects were operated normally,the qualified rate of water fluoride content was 42.11％ (8/19).③The overall rate of dental fluorosis among children aged 8 to 12 years old was 49.28％ (480/974),with the index of dental fluorosis as 1.01 in 19 villages,the prevalence of dental fluorosis was mild.In the qualified villages of water fluoride concentration,the positive rate of dental fluomsis among children aged 8 to 12 was 33.41％ (148/443),dental fluorosis index was 0.65,and the prevalence of dental fluorosis was extremely low;in the exceeding-standard villages of water fluoride content,the positive rate of dental fluorosis among children aged 8 to 12 was 62.52％ (332/531),dental fluorosis index was 1.36,and the prevalence of dental fluorosis was mild;the detection rate of dental fluorosis among children aged 8 to 12 of the villages with qualified fluoride content was lower than the rate of the villages with excessive fluoride (x2 =81.91,P ＜ 0.01).④X-ray detection rate of skeletal fluorosis in adults over the age of 25 was 6.14％ (53/863) in 17 villages,there was no statistically significant difference between the qualified villages and the exceeding-standard villages of water fluoride concentration (x2 =1.55,P ＞ 0.05),X-ray detection rate of skeletal fluorosis in adults was 5.04％ (20/397) and 7.08％ (33/466),respectively.In the qualified villages and the exceeding-standard villages of water fluoride,urinary fluoride geometric average and the exceeding rate of urinary fluoride were 1.50 mg/L,44.16％ (170/385) and 2.09 mg/L,62.58％ (286/466),respectively.In the qualified villages of water fluoride,the exceeding rate of adult urinary fluoride was lower than that in the exceeding-standard villages (x2 =28.58,P ＜ 0.01).Conclusions The prevention and control measures on endemic fluorosis have had some effects in the alluvial plain area of the Yellow River in Shandong Province.But the water fluoride content of water improving defluoridation projects still exceeds the national standard seriously,and endemic fluorosis has not been effectively controlled.Prevention measures should be further strengthened.

Objective To investigate the endemic fluorosis of drinking water type in 3 counties in the northwest of Shandong Province,and to provide scientific basis for prevention and control of endemic fluorosis.Methods Seven villages in 3 counties of Ningjin,Xiajin and Wucheng were investigated to achieve the results including fluoride of drinking water,8-12 year-old children's dental fluorosis incidence rate,the fluoride of urine,prevalence of skeletal fluorosis by clinical and X-ray diagnosis in adults over 30-year old,and the bone mineral density.At the same time,set up a control point to detect the adult bone density in non-ward village of each investigated county,The water and urine fluoride were checked by selective electrode method,dental fluorosis was diagnosed by Dean method (WS/T 208-2011) and the diagnosis of adult fluorosis was performed in accordance with the diagnostic criteria of endemic fluorosis (WS 192-2008),and bone mineral density was measured by EXA-3000.Results The villages in Ningjin and Wucheng had finished defluoridation,where the water fluoride was at normal level.In the 7 villages,the total detection rate of 8-12 year-old children's dental fluorosis was 85.09％ (411/483),dental fluorosis index was 1.88;the dental fluorosis detection rate in Wucheng,Xiajin and Ningjin was 92.48％ (295/319),88.76％ (79/89) and 49.33％ (35/75),respectively,the difference was statistically significant (x2 =90.26,P ＜ 0.01).The average urine fluoride geometric mean of children (206) and adults (298) was 3.29 and 3.41 mg/L,respectively.The urine fluoride of Xiajin was the highest in the 3 counties,and the average urine fluoride geometric mean of the two groups was as high as 5.11 and 6.30 mg/L,respectively.The total detection rate of clinical and radiographic skeletal fluorosis in adults was 30.07％ (92/306) and 14.38％ (44/306),respectively.The osteoporosis detection rate of adults in endemic fluorosis area and non-endemic fluorosis area was 33.11％ (100/302) and 8.99％ (17/189),respectively.The difference was statistically significant (x2 =37.25,P ＜ 0.01);the average bone mineral density in endemic area and non-endemic area was 0.416 and 0.475 g/cm2,respectively,the difference was statistically significant (t =8.508,P ＜ 0.01).Conclusions The endemic fluorosis in the 3 counties in the northwest of Shandong Province is still existed.The defluoridation has not been completed in Xiajin County.Therefore,it is necessary to implement defluoridation measures of the drinking water as soon as possible and strengthen the water fluoride monitoring so as to prevent and control endemic fluorosis.

Objective To study the prevalence of drinking water type of endemic fluorosis in Shandong Province,and to provide a scientific basis in making strategies for prevention and control of the disease.Methods Ten counties (cities,districts) were selected by random number table method to carry out the epidemiological study,and to study the progress and effect of water-improving and defluoridation projects.Three villages in each county (city,district) were chosen to determine fluoride content of drinking water and to check the prevalence of dental fluorosis of children 8 to 12 years old.Water fluoride content was determined with fluoride ion-selective electrode,and dental fluorosis was diagnosed by the Deans method.Results In the 10 counties (cities,districts),a total of 515 water-improving and defluoridation projects were built covering 3 207 fluorosis villages,and the waterimproving rate was 81.71％ (3 207/3 925).A total of 85 water-improving and defluoridation projects were investigated in the 10 counties (cities,districts),and all of the projects were operating normally.The number of projects that water fluoride concentration ≤ 1.20 mg/L was 51; the qualified rate of water fluoride concentration was 60.00％ (51/85),and the maximum value of water fluoride was 4.38 mg/L.A total of 29 villages that had waterimproving and defluoridation projects were investigated in the 10 counties (cities,districts),and the number of villages that mean of water fluoride ≤ 1.20 mg/L was 21,accounting for 72.41％ (21/29); ＞ 1.20 mg/L was 8,accounting for 27.59％ (8/29),and the maximum value of water fluoride was 4.02 mg/L.In the 21 qualified villages of water fluoride concentration,a total of 1 023 children aged 8 to 12 were examined; the positive rate of dental fluorosis was 38.12％ (390/1 023); dental fluorosis index was 0.67,and the prevalence of dental fluorosis was extremely low.In the 8 exceeding-standard villages of water fluoride content,a total of 449 children aged 8 to 12 were examined; the positive rate of dental fluorosis was 54.79％ (246/449); dental fluorosis index was 1.18,and the prevalence of dental fluorosis was mild.Conclusion In Shandong Province,the water fluoride content of waterimproving and defluoridation projects exceeds the national standard seriously,and the condition of children's dental fluorosis is still serious,and the measures of water-defluoridation should be further strengthened.

Objective To investigate the fluoride content in drinking water as well as the current status of endemic fluorosis in 5 counties of Shandong Province,in order to provide a scientific basis for making prevention and control strategies.Methods According to the survey data of fluoride content in drinking water in Shandong Province between 2005 to 2007,an epidemiological investigation was carried out in Mudan,Jiaxiang,Wucheng,Pingdu and Boxing Counties from September to November 2013.The fluoride content in drinking water and urine and dental fluorosis of children aged 8 to 12 were investigated in 3-4 major survey villages selected in the five counties.The fluoride content in drinking water was detected by fluoride ion selective electrode method,and dental fluorosis was diagnosed by Deans method.Results Fifty-eight drinking water samples were investigated in 16 villages of the five counties.Water fluorine content in Wucheng,Mudan,Pingdu,Boxing and Jiaxiang counties was 4.14,3.84,1.83,1.33 and 0.43 mg/L,respectively.There were 4 counties' fluorine content exceeding the national standard (1.20 mg/L) except Jiaxiang County.The exceeding rate was 100％ in Wucheng and Mudan counties.Urine fluorine content of 320 children aged 8 to 12 in Wucheng,Mudan,Boxing,Pingdu and Jiaxiang counties was 4.51,4.62,1.82,1.30,1.01 mg/L respectively;the total detection rate of dental fluorosis of 574 children was 61.85％ (355/574),the rate of dental damage was 12.89％ (74/574),and dental fluorosis index was 1.27;the detection rate of dental fluorosis in Wucheng,Mudan,Boxing,Pingdu and Jiaxiang Counties was 90.18％ (101/112),97.73％ (86/88),62.22％ (84/135),54.90％ (28/51) and 29.79％ (56/188),respectively.Conclusions The exceeding rate of water fluorine content is very high in 5 counties of severe endenic fluorosis areas in Shandong Province.The urinary fluorine level of the population is still high and the prevalence of dental fluorosis of children is high.Endemic fluorosis in Shandong Province has not yet been effectively controlled,control situation is still grim.

Objective To understand the schedule and effectiveness of water-improving defluoridation projects comprehensively of control of fluorosis in drinking-water-borne endemic fluorosis areas in Shandong Province,and to provide a scientific basis for making strategies for prevention and control of the disease.Methods In accordance with the requirements of Shandong Provincial Survey Scheme for Implementation of Prevention and Control Measures of Endemic Fluorosis,the progress of water-improving defluoridation projects was investigated in Shandong Province.The types of water source,scale and operating conditions for water-improving defluoridation projects in 17 cities of the province were investigated.Water fluoride contents of the normal operating projects were detected by F-ion selective electrode.Results ① By the end of 2012,a total of 3 539 water-improving defluoridation projects were built that covered 9 856 fluorosis villages,113 counties,17 cities in the province,and the water-improving rate was 91.01％ (9 856/10 830).The type of water source of water-improving project was mainly groundwater,accounted for 93.78％ (3 319/3 539) of the total projects.As for the scale of the water-improving projects,small centralized water supply projects were the main projects,accounted for 92.96％(3 290/3 539) of the total projects.\)Of all the water-improving defluoridation projects,normal operating projects accounted for 89.12％(3 154/3 539),intermittent and scrapped projects accounted for 3.25％(115/3 539) and 7.63％ (270/3 539),respectively.③Among normal operating projects,the number of projects with water fluoride content ≤ 1.20 mg/L was 1 925,accounted for 72.40％(1 925/2 659).The number of projects with water fluoride content ＞ 1.20 mg/L was 734,accounted for 27.60％ (734/2 659); among them water fluoride contents between 2.01-4.00 mg/L and ＞ 4.00 mg/L were 233 and 65,respectively,and the highest water fluoride value was 9.71 mg/L.Conclusions The progress of water-improving projects in some cities (counties) of Shandong Province is still slow.Some of the water-improving projects can not be operated normally or have been scrapped,and water fluoride content has exceeded the standard seriously.So the prevention and control measures need to be further strengthened,funding should be increased,and the operating conditions and water quality of the water-improving defluoridation projects in Shandong need to be further improved.

Objective To evaluate the photo quality of X-ray films of endemic fluorosis in Shandong Province,and to provide a basis for correct implementation of X-ray examination.Methods Three villages were selected as survey sites in each of the 20 endemic fluorosis counties (cities,districts) of Shandong Province;anteroposterior X-ray films of the villagers forearm(including elbow) and leg(including knee) were taken; 20 films were taken in each village,each film comprising two recording sites.X-ray examination carried out in the 42 patients' villages of 14 counties(cities,districts) were undertaken by the Institute for Endemic Disease Control,Shandong Province,a total of 840 X-ray films shoot,which was edited group A,and the remaining six counties (cities,districts) were undertaken by the local Hospital,shooting X-ray films 360 copies,compiled for group B.The quality of X-ray film examination was determined in accordance with technical requirements and diagnostic indicators.The difference of photo quality between group A and group B was compared at three levels:sub-surface defects photos,structural defects and comprehensive quality.Results In evaluation of surface defects in the photo,the total detection rate of the defects indicators in group A of forearm was 7.98％(67/840),while the rate of leg was 9.77％(82/840).And the rates of group B were 35.27％(127/360) and 39.16％(141/360),respectively,and the differences were statistically significant between the two groups(x2forearm=138.6,P ＜ 0.01 ; x2leg =144.0,P ＜ 0.01).In assessment of structural defects,the total forearm defection rate of group A was 7.14％(60/840),and the leg was 8.33％ (70/840).And the rates of group B were 27.22％ (98/360) and 31.38％ (113/360),respectively.The differences were statistically significant(x2forearm =88.867,P ＜ 0.01; x2leg =103.6,P ＜ 0.01).In the photo quality comprehensive assessment,the excellent rate of forearm in group A was 72.73％(611/840),and the leg was 71.67％ (602/840),while the poor quality rates in the same parts were 9.89％ (83/840) and 11.43％ (96/840),respectively.And the excellent rates of Group B were 44.14％(159/360) and 42.22％(152/360),poor quality rates were 34.74％(125/360) and 38.06％(137/360).The differences were statistically significant(Z value were-20.161 and-16.229,respectively,P ＜ 0.01).Conclusions X-ray films taken in the counties (cities,districts) have more defects,and image is poor.The reason for that is that the skill levels of local hospital X-ray technician are low,and photos quality is not strictly followed requirements.Supervision team of professional technicians should be established to provide professional supports.It is more important to take mobile X-ray examination by the provincial institutes,and to provide a reliable technical support.

Objective To understand the status of endemic fluorosis in Shandong Province.Methods In accordance with the requirements of the National Surveillance Scheme of Drinking-Water-Type Endemic Fluorosis (Trial) and Shandong Provincial Surveillance Scheme of Drinking-Water-Type Endemic Fluorosis (Trial),ten counties (cities,districts) were chosen in the province,and ten water-improvement projects were selected in each county (city,district).The operating effect of water-improvement projects was investigated; one peripheral water sample of each project was collected,and water fluoride content was tested.Three epidemic villages were chosen as fixed monitoring villages in each county (city,district).In the villages that had changed water source,one peripheral water sample was collected; in unchanged water source villages,one water sample was collected following five different directions of the east,the west,the south,the north and the center of the water source location; and the water fluoride content was tested.All students aged 8 to 12 were checked for dental fluorosis in the monitoring villages.The fluoride content in drinking water was detected by fluoride ion selective electrode method,and dental fluorosis was diagnosed by Dean's method.Results ① In the 10 counties (cities,districts),a total of 85 water-improving projects were monitored,and all the projects were in normal operation; the water fluoride contents of 47 projects were qualified,and the qualified rate of water fluoride content was 55.29％(47/85),with the maximum of water fluoride content was 4.74 mg/L.② In the 30 fixed monitoring villages,27 monitored villages had water-improving projects; water fluoride contents of 19 villages were qualified,the qualified rate of water fluoride content was 70.37％ (19/27),with the maximum of water fluoride content was 4.77 mg/L.In the 3 monitored villages without water-improving projects,villages of mean water fluoride contents ≤ 1.20 mg/L and ＞ 1.20 mg/L were two and one,respectively,with the maximum of water fluoride content was 1.55 mg/L.③ In the 19 monitored villages with water-improving projects that in normal operating condition with qualified water fluoride content,the detected rates of dental fluorosis and the defect type of dental fluorosis among children aged 8 to 12 years old were 52.37％(508/970) and 6.39％(62/970),respectively,and the index of dental fluorosis was 1.02.In the 8 monitored villages with water-improving projects that in normal operating condition with water fluoride content that exceeded the national standard,the detected rates of dental fluorosis and the defect type of dental fluorosis were 62.39％ (297/476) and 8.82％ (42/476),respectively,and the index of dental fluorosis was 1.67.In the 3 monitored villages without water-improving projects,the detected rates of dental fluorosis and the defect type of dental fluorosis were 49.45％ (90/182) and 7.14％ (13/182),respectively,and the index of dental fluorosis was 1.25.Conclusions In Shandong Province,the water fluoride content of water-improving defluoridation projects exceeds the national standard seriously,and water quality of the projects still need to be further improved.The projects of water-improving defluoridation play a certain role in control of dental fluorosis condition,but the condition of children' s dental fluorosis is still very serious.So preventive and control measures for endemic fluorosis should be further strengthened.

Objective To understand the status quo of the illness situation and the implementation of prevention and control measures on Kashin-Beck disease( KBD ) in Shandong Province , and provide a scientific basis for assessment and acceptance of the work on eliminating KBD. Methods In accordance with the requirements of the national “Implementation Scheme for Endemic Disease Control in 2012” and the “Shandong Provincial Technical Scheme for KBD Control in 2012”. In four towns of Qingzhou, three epidemic villages were selected as the surveying villages in each town in order to understand the implementation of measures for prevention and control of KBD; information such as population of investigating villages, per capita income, farming, food and the implementation of control measures,etc were included. In each investigating village, 7 - 12 years old children were selected to receive clinical and X-ray examination. When fewer than 50 people in a investigating village , one additional endemic village was included near the investigating village , and all children aged 7 to 12 of the village were checked. The number of cases of clinical degree Ⅰ, Ⅱ, Ⅲand the detection rates, X-ray positive detection rate, the number of cases of metaphysis, epiphysis, distal end of phalanx, carpal bone, triad and the detection rates were calculated, respectively. Clinical and X-ray diagnosis were based on “The Diagnostic Criteria of Kaschin-Beck disease”(WS/T 207-2010). Results A total of 14 epidemic villages were selected to survey in four towns of Qingzhou. In the recent three years in the epidemic areas, measures of supplying Se had not been implemented;measures of resettlement and off-site education had not been implemented either. In the epidemic areas , the main crops were wheat and corn; the staple food was flour which accounted for more than 80%, and the foreign food bought accounted for only 11%. The areas of returning farmland to forest (grass) accounted for 0.32%(36/11 151) of the original arable land, and the areas of replanting economic crops accounted for 1.17%(131/11 151) of the original farmland. A total of 536 children aged 7 to 12 were examined by clinical and X-rays. Patient of KBD was not detected clinically. Six positive patients with metaphyseal changes of KBD were detected by X-rays, and the average X-ray detection rate was 1.12%(6/536). Patients with abnormal epiphysis, distal end of phalanx and carpal bone were not detected by X-rays. Conclusions KBD in Shandong Province has been effectively controlled. Since the cause of KBD is still unknown, it is necessary to build a sustainable long-term control mechanism of KBD;further improve the monitoring system and dynamic monitoring work still need to be strengthened.