Endodontic diseases are a kind of chronic infectious oral disease. Common endodontic treatment concepts are based on the removal of inflamed or necrotic pulp tissue and the replacement by gutta-percha. However, it is ...Endodontic diseases are a kind of chronic infectious oral disease. Common endodontic treatment concepts are based on the removal of inflamed or necrotic pulp tissue and the replacement by gutta-percha. However, it is very essential for endodontic treatment to debride the root canal system and prevent the root canal system from bacterial reinfection after root canal therapy(RCT). Recent research, encompassing bacterial etiology and advanced imaging techniques, contributes to our understanding of the root canal system’s anatomy intricacies and the technique sensitivity of RCT. Success in RCT hinges on factors like patients, infection severity, root canal anatomy, and treatment techniques. Therefore, improving disease management is a key issue to combat endodontic diseases and cure periapical lesions. The clinical difficulty assessment system of RCT is established based on patient conditions, tooth conditions, root canal configuration, and root canal needing retreatment, and emphasizes pre-treatment risk assessment for optimal outcomes. The findings suggest that the presence of risk factors may correlate with the challenge of achieving the high standard required for RCT. These insights contribute not only to improve education but also aid practitioners in treatment planning and referral decision-making within the field of endodontics.展开更多
Background:This study aims to predict the extraction difficulty of mandibular third molars based on panoramic images using transfer learning while employing super-resolution(SR)technology to enhance the feasibility an...Background:This study aims to predict the extraction difficulty of mandibular third molars based on panoramic images using transfer learning while employing super-resolution(SR)technology to enhance the feasibility and validity of the prediction.Methods:We reviewed a total of 608 preoperative mandibular third molar panoramic radiographs from two medical facilities:the First Affiliated Hospital of Zhengzhou University(n=509;456 in the training set and 53 in the test set)and the Henan Provincial Dental Hospital(n=99 in the validation set).We conducted a deep-transfer learning network on high-resolution(HR)panoramic radiographs to improve the longitudinal resolution of the images and obtained the SR images.Subsequently,we constructed models named Model-HR and Model-SR using high-dimensional quantitative features extracted through the Least Absolute Shrinkage and Selection Operator method.The models’performances were evaluated using the receiver operating characteristic curve(ROC).To assess the reliability of the model,we compared the results from the test set with those of three dentists.Results:Model-SR outperformed Model-HR(area under the curve(AUC):0.779,sensitivity:85.5%,specificity:60.9%,and accuracy:79.8%vs.AUC:0.753,sensitivity:73.7%,specificity:73.9%,and accuracy:73.7%)in predicting the difficulty of extracting mandibular third molars.Both Model-HR(AUC=0.821,95%CI 0.687–0.956)and Model-SR(AUC=0.963,95%CI 0.921–0.999)demonstrated superior performance compared to expert dentists(highest AUC=0.799,95%CI 0.671–0.927).Conclusions:Model-SR yielded superior predictive performance in determining the difficulty of extracting mandibular third molars when compared with Model-HR and expert dentists’visual assessments.展开更多
As a highly integrative and demanding receptive skill,listening comprehension presents a challenge to both learners and researchers.The study reported in this paper is listening comprehension objective-factor research...As a highly integrative and demanding receptive skill,listening comprehension presents a challenge to both learners and researchers.The study reported in this paper is listening comprehension objective-factor research.Manipulating topic factors,the study investigated the effect of topic familiarity and linguistic difficulty on EFL(English as a foreign language)listening comprehension of learners at different proficiency levels.展开更多
With the continuous increase in vertical depths and horizontal displacements of directional wells,the difficulties of drilling operations continue to increase,and more accurate methods of drilling difficulty evaluatio...With the continuous increase in vertical depths and horizontal displacements of directional wells,the difficulties of drilling operations continue to increase,and more accurate methods of drilling difficulty evaluation are needed.In this paper,a drilling difficulty evaluation method is built by combining drilling limit model and expert evaluation.Firstly,the concept of drilling difficulty index is introduced,and the method to calculate drilling difficulty index is established.Next,the meanings of five drilling difficulty levels are explained and the optimization design method with drilling difficulty as the target is built.At last,the theoretical model is applied to the extended-reach drilling of the Liuhua oilfield in the South China Sea,in which drilling difficulties are evaluated and the relationship between drilling difficulty and development control radius is revealed.The results indicate that extended-reach drilling in the Liuhua oilfield is on the“normal”difficulty level on average,rotary drilling in 8_(1/2)-in.section is the most difficult,and the main constraint conditions are excessive torque and high friction.Through technology upgradation,the drilling difficulties are decreased,the development control radius increases from 6.6 to 11.4 km,and the maximum horizontalto-vertical ratio increases from 5.3 to 8.7.Then,the development wells in marginal oilfields and adjustment wells in old oilfields can be drilled on“normal”difficulty level.Therefore,technology upgradation,especially drilling rig upgradation,is the most important development direction for extended-reach drilling in the South China Sea.展开更多
Objective:To determine the effect of rehabilitation education on pain,knee stiffness and performance difficulty in patients undergoing knee replacement surgery.Methods:This randomized clinical trial study was performe...Objective:To determine the effect of rehabilitation education on pain,knee stiffness and performance difficulty in patients undergoing knee replacement surgery.Methods:This randomized clinical trial study was performed on 96 patients undergoing knee replacement surgery,who were randomly divided into two groups:the control group and the intervention group,with 48 patients in each group.In the intervention group,the patients received educational intervention in four stages one day before surgery,24 h and 48 h later,upon discharge from the hospital.In the control group,only the routine of the hospital was performed.Questionnaires were completed before and 6 weeks after the intervention.Results:The mean scores of pain,knee stiffness and performance difficulty were significantly decreased in the intervention group(P=0.01).Compared to the control group,the intervention group had a better outcome of the illness,including pain,knee stiffness and performance difficulty(P=0.001).Conclusion:Rehabilitation education could be a suitable way to improve the surgical outcomes of patients undergoing total knee replacement.展开更多
Students'preferences and engagement with online educational resources and activities are crucial for academic success in the context of online medical education.This study investigated the preferences of Chinese m...Students'preferences and engagement with online educational resources and activities are crucial for academic success in the context of online medical education.This study investigated the preferences of Chinese medical students regarding the teaching strategies used by instructors and their relationship with course difficulty level,students'academic performance and perceived effectiveness.Survey data(n=375)was collected from the medical students from one of the largest medical schools in Southern China during the spring semester of 2020.展开更多
The three most common variations of Fitts’ index of difficulty are the Fitts formulation, the Welford formulation, and the Shannon formulation. A recent paper by Hoffmann [1] critiqued the three and concluded that th...The three most common variations of Fitts’ index of difficulty are the Fitts formulation, the Welford formulation, and the Shannon formulation. A recent paper by Hoffmann [1] critiqued the three and concluded that the Fitts and Welford formulations are valid and that the Shannon formulation is invalid. In this paper, we challenge Hoffmann’s position regarding the Shannon formulation. It is argued that the issue of validity vs. invalidity is ill-conceived, given that Fitts’ law is a “model by analogy” with no basis in human motor control. The relevant questions are of utility: Does a model work? How well? Is it useful? Where alternative formulations exist, they may be critiqued and compared for strengths and weaknesses, but validity is an irrelevant construct. In a reanalysis of data from Fitts’ law experiments, models built using the Shannon formulation are (re)affirmed to be as good as, and generally better than, those built using the Fitts or Welford formulation.展开更多
The range of optimal values in cost optimization models provides management with options for decision making. However, it can be quite challenging to achieve feasible range of optimality in Geometric programming (Gp) ...The range of optimal values in cost optimization models provides management with options for decision making. However, it can be quite challenging to achieve feasible range of optimality in Geometric programming (Gp) models having negative degrees of difficulty. In this paper, we conduct sensitivity analysis on the optimal solution of Geometric programming problem with negative degree of difficulty. Using imprest data, we determine the optimal objective function, dual decision variables, primal decision variables;the range of values, the cost coefficient and RHS constraint must lie for the solution to stay optimal. From the analysis, we established that incremental sensitivity analysis has the functional form .展开更多
With the promoting of world integration,the role of English listening and speaking is becoming more and more important.English listening is attached more importance to in higher education.Although many universities an...With the promoting of world integration,the role of English listening and speaking is becoming more and more important.English listening is attached more importance to in higher education.Although many universities and college students take different measures to improve the students’English listening abilities,it is found that it is difficult to improve the students’English listening abilities effectively.This article will analyze the reasons of students’difficulty in improving their listening in the aim at discussing the measures to improve the students’listening effectively with other educators.展开更多
Editor’s note Guangzhou Glaucoma Forum(GZGF)was successfully held in the Zhongshan Ophthalmology Center on April 21-22,2018.The forum gathered domestic and international experts from all over the world,including Prof...Editor’s note Guangzhou Glaucoma Forum(GZGF)was successfully held in the Zhongshan Ophthalmology Center on April 21-22,2018.The forum gathered domestic and international experts from all over the world,including Prof.Larry Benowitz from Harvard Medical School,Prof.Leopold Schmetterer from Singapore Eye Research Institute,Prof.Anuj Chauhan from University of Florida,Prof.Shlomo Melamed from Israel,and Prof.Keith Barton from Moorfields Eye Hospital.AME editorial team had the honor to interview Prof.Benowitz.展开更多
Ensuring program satisfaction for undergraduate students in the areas of science,technology,engineering and mathematics(STEM)matters in student retention and education quality improvement.This study explores how four ...Ensuring program satisfaction for undergraduate students in the areas of science,technology,engineering and mathematics(STEM)matters in student retention and education quality improvement.This study explores how four rarely examined variables support from faculty members,interdisciplinary features of STEM program courses,disciplinary connectedness of STEM program core courses,and examination difficulty impact Chinese STEM undergraduates’program satisfaction.With data from 619 Chinese STEM undergraduates,structural equation modeling shows that course satisfaction partially mediates the impact of support from faculty members on program satisfaction,while fully mediating that of interdisciplinary features of STEM program courses and disciplinary connectedness of STEM program core courses on program satisfaction.Examination difficulty exerts no significant impact on program satisfaction neither directly nor indirectly.Support from faculty members impact course satisfaction significantly stronger for junior and senior students than for freshmen and sophomores,while interdisciplinary features of STEM program courses impact course satisfaction stronger for freshmen and sophomores than for juniors and seniors.The study ends with practical implications for the higher education reform in relevant areas.展开更多
AIM:To investigate whether perceptions of task difficulty on neuropsychological tests predicted academic achievement after controlling for glucose levels and depression.METHODS :Participants were type 1 diabetic adole...AIM:To investigate whether perceptions of task difficulty on neuropsychological tests predicted academic achievement after controlling for glucose levels and depression.METHODS :Participants were type 1 diabetic adolescents,with a mean age = 12.5 years(23 females and 16 males),seen at a northwest suburban Chicago hospital.The sample population was free of comorbid clinical health conditions.Subjects completed a three-part neuropsychological battery including the Digit Symbol Task,Trail Making Test,and Controlled Oral Word Association test.Following each task,individuals rated task difficulty and then completed a depression inventory.Performance on these three tests is reflective of neuropsychological status in relation to glucose control.Blood glucose levels were measured immediately prior to and after completing the neuropsychological battery using a glucose meter.Hb A1 c levels were obtained from medical records.Academic performance was based on self-reported grades in Math,Science,and English.Data was analyzed using multiple regression models to evaluate the associations between academic performance,perception of task difficulty,and glucose control.RESULTS:Perceptions of difficulty on a neuropsychological battery significantly predicted academic performance after accounting for glucose control and depression.Perceptions of difficulty on the neuropsychological tests were inversely correlated with academic performance(r =-0.48),while acute(blood glucose) and long-term glucose levels increased along with perceptions of task difficulty(r = 0.47).Additionally,higher depression scores were associatedwith poorer academic performance(r =-0.43).With the first regression analysis,perception of difficulty on the neuropsychological tasks contributed to 8% of the variance in academic performance after controlling for peripheral blood glucose and depression.In the second regression analysis,perception of difficulty accounted for 11% of the variance after accounting for academic performance and depression.The final regression analysis indicated that perception of difficulty increased with peripheral blood glucose,contributing to 22% of the variance.Most importantly,after controlling for perceptions of task difficulty,academic performance no longer predicted glucose levels.Finally,subjects who found the cognitive battery difficult were likely to have poor academic grades.CONCLUSION:Perceptions of difficulty on neurological tests exhibited a significant association with academic achievement,indicating that deficits in this skill may lead to academic disadvantage in diabetic patients.展开更多
Pygmalion Effect refers to the expectation from teachers have stimulative effects on students' learning. English educa-tion of junior middle school has its unique nature, and the phenomenon of having trouble in le...Pygmalion Effect refers to the expectation from teachers have stimulative effects on students' learning. English educa-tion of junior middle school has its unique nature, and the phenomenon of having trouble in learning English in middle school stu-dents exists generally. So, the key point of this research is how the students use Pygmalion Effect to improve their English Learn-ing.展开更多
The difficulty of extracting hidden information, which is essentially a kind of secrecy, is analyzed by information-theoretic method. The relations between key rate, message rate, hiding capacity and difficulty of ext...The difficulty of extracting hidden information, which is essentially a kind of secrecy, is analyzed by information-theoretic method. The relations between key rate, message rate, hiding capacity and difficulty of extraction are studied in the terms of unicity distance of stego-key, and the theoretic conclusion is used to analyze the actual extracting attack on Least Significant Bit(LSB) steganographic algorithms.展开更多
Distinguishing the difficulty degree of top coal caving was a precondition of the popularization and application of the roadway sub-level caving in steep seam. Because of complexity and uncertainty of the coal seam, t...Distinguishing the difficulty degree of top coal caving was a precondition of the popularization and application of the roadway sub-level caving in steep seam. Because of complexity and uncertainty of the coal seam, the expression of influence factors was diffi-culty with exact data. According to the fuzzy and uncertainty of influence factors, triangular fuzzy membership functions were adopted to carry out the factors ambiguity, of which the factors not only have the consistency of semantic meaning, but also dissolve sufficiently expert knowledge. Based on the properties and structures of fasART fuzzy neural net-works of fuzzy logic system and practical needs, a simplified fasART model was put for-ward, stability and reliability of the network were improved, the deficiency of learning sam-ples and uncertainty of the factors were better treated. The method is of effective and practical value was identified by experiments.展开更多
Objective To identify the target behavior in the process of behavioral intervention for children with feeding difficulty and relevant factors that may contribute to more effective intervention.Methods Children aged fr...Objective To identify the target behavior in the process of behavioral intervention for children with feeding difficulty and relevant factors that may contribute to more effective intervention.Methods Children aged from 1 to 6 years with feeding difficulty randomly received interactive behavioral intervention(245 cases)or routine primary care(217 cases).By the end of the 1,3,6,and 9 months,the rating score of feeding difficulty and the body mass index(BMI)were assessed.The target behavior was determined based on the selecting criteria that simultaneously satisfied two conditions:①it was relevant to improving children's nutritional status;②it changed fast during intervention.Moreover,the relevant factors of target behavior were analyzed by multivariate analysis(Multi-Way ANOVA).Results Among nine behaviors of feeding difficulty,"eating slowly"was identified as a target behavior because it was closely relevant to the BMI z-score increment and had the biggest score reduction at early stage during intervention.Various factors were relevant to improving the target behavior,including parents acting as caregivers,caregiver's education level equal to and above junior college,and caregiver's concern about their children's feeding difficulty.Conclusion"Eating slowly"should be selected as the target behavior for early intervention for children with feeding difficulty and some social factors should be considered for optimizing the intervention.展开更多
Transcranial direct current stimulation(t DCS), an emerging technique for non-invasive brain stimulation, is increasingly used to induce changes in cortical excitability and modulate motor behavior, especially for upp...Transcranial direct current stimulation(t DCS), an emerging technique for non-invasive brain stimulation, is increasingly used to induce changes in cortical excitability and modulate motor behavior, especially for upper limbs. The purpose of this study was to investigate the effects of t DCS of the primary motor cortex on visuomotor coordination based on three levels of task difficulty in healthy subjects. Thirty-eight healthy participants underwent real t DCS or sham t DCS. Using a single-blind, sham-controlled crossover design, t DCS was applied to the primary motor cortex. For real t DCS conditions, t DCS intensity was 1 m A while stimulation was applied for 15 minutes. For the sham t DCS, electrodes were placed in the same position, but the stimulator was turned off after 5 seconds. Visuomotor tracking task, consisting of three levels(levels 1, 2, 3) of difficulty with higher level indicating greater difficulty, was performed before and after t DCS application. At level 2, real t DCS of the primary motor cortex improved the accurate index compared to the sham t DCS. However, at levels 1 and 3, the accurate index was not significantly increased after real t DCS compared to the sham t DCS. These findings suggest that tasks of moderate difficulty may improve visuomotor coordination in healthy subjects when t DCS is applied compared with easier or more difficult tasks.展开更多
Introduction: The use of foods containing high levels of sugar is increasing all the time. This is a risk factor for increased incidence of type 2 diabetes. There are few studies that have investigated the availabilit...Introduction: The use of foods containing high levels of sugar is increasing all the time. This is a risk factor for increased incidence of type 2 diabetes. There are few studies that have investigated the availability of low-sugar müsli products in grocery stores. Purpose: The study aims to identify which types of müsli contain high respectively low levels of sugar, and which brands are involved. Methods: The material consists of both qualitative interviews and observations from five grocery stores: City Gross, Hemköp, Ica Maxi, Stora Coop and Willy’s in Helsingborg, Sweden. The qualitative interviews had a semi-structured character and were recorded. The interviews took approx. 20 minutes and a textual analysis was conducted of the results. Data from observation was analyzed based on brand, nutritional composition and flavors, and also, where low sugar products were placed on store shelves. Results: The grocery stores provided together brands from AXA, Coop, Finax, Frebaco, Garant, ICA, Risenta, Saltå Kvarn och Urtekram, in total 24 müsli products. Of these products, 19 were high in sugar. The observation reveals that müsli products with high sugar content (17 - 29 g per 100 g müsli) are more prominently displayed than those with low sugar content. From the interviews with the store managers, it became clear that it would be valuable to highlight healthy müsli products on the shelves. However, central bureaucracy puts obstacles to such measures. Discussion: The study emphasizes the need for increased visibility of low-sugar products and proposes solutions such as negotiating with responsible person at the head office in Stockholm. Several reviews have shown that if the grocery store raises the prices of unhealthy food, the consumer is willing to purchase healthier müsli and other products. Conclusion: This study shows the need for grocery stores to upgrade healthy müsli products along with advertising to be able to influence customer’s shopping habits. Also, further research is needed how type 2 diabetes is affected by high intakes of food products with high sugar content.展开更多
文摘Endodontic diseases are a kind of chronic infectious oral disease. Common endodontic treatment concepts are based on the removal of inflamed or necrotic pulp tissue and the replacement by gutta-percha. However, it is very essential for endodontic treatment to debride the root canal system and prevent the root canal system from bacterial reinfection after root canal therapy(RCT). Recent research, encompassing bacterial etiology and advanced imaging techniques, contributes to our understanding of the root canal system’s anatomy intricacies and the technique sensitivity of RCT. Success in RCT hinges on factors like patients, infection severity, root canal anatomy, and treatment techniques. Therefore, improving disease management is a key issue to combat endodontic diseases and cure periapical lesions. The clinical difficulty assessment system of RCT is established based on patient conditions, tooth conditions, root canal configuration, and root canal needing retreatment, and emphasizes pre-treatment risk assessment for optimal outcomes. The findings suggest that the presence of risk factors may correlate with the challenge of achieving the high standard required for RCT. These insights contribute not only to improve education but also aid practitioners in treatment planning and referral decision-making within the field of endodontics.
基金supported by the National Natural Science Foundation of China(U1904145)the Joint Funds for the Innovation of Science and Technology of Fujian province(2019Y9128).
文摘Background:This study aims to predict the extraction difficulty of mandibular third molars based on panoramic images using transfer learning while employing super-resolution(SR)technology to enhance the feasibility and validity of the prediction.Methods:We reviewed a total of 608 preoperative mandibular third molar panoramic radiographs from two medical facilities:the First Affiliated Hospital of Zhengzhou University(n=509;456 in the training set and 53 in the test set)and the Henan Provincial Dental Hospital(n=99 in the validation set).We conducted a deep-transfer learning network on high-resolution(HR)panoramic radiographs to improve the longitudinal resolution of the images and obtained the SR images.Subsequently,we constructed models named Model-HR and Model-SR using high-dimensional quantitative features extracted through the Least Absolute Shrinkage and Selection Operator method.The models’performances were evaluated using the receiver operating characteristic curve(ROC).To assess the reliability of the model,we compared the results from the test set with those of three dentists.Results:Model-SR outperformed Model-HR(area under the curve(AUC):0.779,sensitivity:85.5%,specificity:60.9%,and accuracy:79.8%vs.AUC:0.753,sensitivity:73.7%,specificity:73.9%,and accuracy:73.7%)in predicting the difficulty of extracting mandibular third molars.Both Model-HR(AUC=0.821,95%CI 0.687–0.956)and Model-SR(AUC=0.963,95%CI 0.921–0.999)demonstrated superior performance compared to expert dentists(highest AUC=0.799,95%CI 0.671–0.927).Conclusions:Model-SR yielded superior predictive performance in determining the difficulty of extracting mandibular third molars when compared with Model-HR and expert dentists’visual assessments.
文摘As a highly integrative and demanding receptive skill,listening comprehension presents a challenge to both learners and researchers.The study reported in this paper is listening comprehension objective-factor research.Manipulating topic factors,the study investigated the effect of topic familiarity and linguistic difficulty on EFL(English as a foreign language)listening comprehension of learners at different proficiency levels.
基金the financial support from the Natural Science Foundation of China(Grant Nos.51904317 and 51821092)Science Foundation of China University of Petroleum,Beijing(Grant No.ZX20180414)other projects(ZLZX2020-0107-01)
文摘With the continuous increase in vertical depths and horizontal displacements of directional wells,the difficulties of drilling operations continue to increase,and more accurate methods of drilling difficulty evaluation are needed.In this paper,a drilling difficulty evaluation method is built by combining drilling limit model and expert evaluation.Firstly,the concept of drilling difficulty index is introduced,and the method to calculate drilling difficulty index is established.Next,the meanings of five drilling difficulty levels are explained and the optimization design method with drilling difficulty as the target is built.At last,the theoretical model is applied to the extended-reach drilling of the Liuhua oilfield in the South China Sea,in which drilling difficulties are evaluated and the relationship between drilling difficulty and development control radius is revealed.The results indicate that extended-reach drilling in the Liuhua oilfield is on the“normal”difficulty level on average,rotary drilling in 8_(1/2)-in.section is the most difficult,and the main constraint conditions are excessive torque and high friction.Through technology upgradation,the drilling difficulties are decreased,the development control radius increases from 6.6 to 11.4 km,and the maximum horizontalto-vertical ratio increases from 5.3 to 8.7.Then,the development wells in marginal oilfields and adjustment wells in old oilfields can be drilled on“normal”difficulty level.Therefore,technology upgradation,especially drilling rig upgradation,is the most important development direction for extended-reach drilling in the South China Sea.
文摘Objective:To determine the effect of rehabilitation education on pain,knee stiffness and performance difficulty in patients undergoing knee replacement surgery.Methods:This randomized clinical trial study was performed on 96 patients undergoing knee replacement surgery,who were randomly divided into two groups:the control group and the intervention group,with 48 patients in each group.In the intervention group,the patients received educational intervention in four stages one day before surgery,24 h and 48 h later,upon discharge from the hospital.In the control group,only the routine of the hospital was performed.Questionnaires were completed before and 6 weeks after the intervention.Results:The mean scores of pain,knee stiffness and performance difficulty were significantly decreased in the intervention group(P=0.01).Compared to the control group,the intervention group had a better outcome of the illness,including pain,knee stiffness and performance difficulty(P=0.001).Conclusion:Rehabilitation education could be a suitable way to improve the surgical outcomes of patients undergoing total knee replacement.
文摘Students'preferences and engagement with online educational resources and activities are crucial for academic success in the context of online medical education.This study investigated the preferences of Chinese medical students regarding the teaching strategies used by instructors and their relationship with course difficulty level,students'academic performance and perceived effectiveness.Survey data(n=375)was collected from the medical students from one of the largest medical schools in Southern China during the spring semester of 2020.
文摘The three most common variations of Fitts’ index of difficulty are the Fitts formulation, the Welford formulation, and the Shannon formulation. A recent paper by Hoffmann [1] critiqued the three and concluded that the Fitts and Welford formulations are valid and that the Shannon formulation is invalid. In this paper, we challenge Hoffmann’s position regarding the Shannon formulation. It is argued that the issue of validity vs. invalidity is ill-conceived, given that Fitts’ law is a “model by analogy” with no basis in human motor control. The relevant questions are of utility: Does a model work? How well? Is it useful? Where alternative formulations exist, they may be critiqued and compared for strengths and weaknesses, but validity is an irrelevant construct. In a reanalysis of data from Fitts’ law experiments, models built using the Shannon formulation are (re)affirmed to be as good as, and generally better than, those built using the Fitts or Welford formulation.
文摘The range of optimal values in cost optimization models provides management with options for decision making. However, it can be quite challenging to achieve feasible range of optimality in Geometric programming (Gp) models having negative degrees of difficulty. In this paper, we conduct sensitivity analysis on the optimal solution of Geometric programming problem with negative degree of difficulty. Using imprest data, we determine the optimal objective function, dual decision variables, primal decision variables;the range of values, the cost coefficient and RHS constraint must lie for the solution to stay optimal. From the analysis, we established that incremental sensitivity analysis has the functional form .
文摘With the promoting of world integration,the role of English listening and speaking is becoming more and more important.English listening is attached more importance to in higher education.Although many universities and college students take different measures to improve the students’English listening abilities,it is found that it is difficult to improve the students’English listening abilities effectively.This article will analyze the reasons of students’difficulty in improving their listening in the aim at discussing the measures to improve the students’listening effectively with other educators.
文摘Editor’s note Guangzhou Glaucoma Forum(GZGF)was successfully held in the Zhongshan Ophthalmology Center on April 21-22,2018.The forum gathered domestic and international experts from all over the world,including Prof.Larry Benowitz from Harvard Medical School,Prof.Leopold Schmetterer from Singapore Eye Research Institute,Prof.Anuj Chauhan from University of Florida,Prof.Shlomo Melamed from Israel,and Prof.Keith Barton from Moorfields Eye Hospital.AME editorial team had the honor to interview Prof.Benowitz.
文摘Ensuring program satisfaction for undergraduate students in the areas of science,technology,engineering and mathematics(STEM)matters in student retention and education quality improvement.This study explores how four rarely examined variables support from faculty members,interdisciplinary features of STEM program courses,disciplinary connectedness of STEM program core courses,and examination difficulty impact Chinese STEM undergraduates’program satisfaction.With data from 619 Chinese STEM undergraduates,structural equation modeling shows that course satisfaction partially mediates the impact of support from faculty members on program satisfaction,while fully mediating that of interdisciplinary features of STEM program courses and disciplinary connectedness of STEM program core courses on program satisfaction.Examination difficulty exerts no significant impact on program satisfaction neither directly nor indirectly.Support from faculty members impact course satisfaction significantly stronger for junior and senior students than for freshmen and sophomores,while interdisciplinary features of STEM program courses impact course satisfaction stronger for freshmen and sophomores than for juniors and seniors.The study ends with practical implications for the higher education reform in relevant areas.
文摘AIM:To investigate whether perceptions of task difficulty on neuropsychological tests predicted academic achievement after controlling for glucose levels and depression.METHODS :Participants were type 1 diabetic adolescents,with a mean age = 12.5 years(23 females and 16 males),seen at a northwest suburban Chicago hospital.The sample population was free of comorbid clinical health conditions.Subjects completed a three-part neuropsychological battery including the Digit Symbol Task,Trail Making Test,and Controlled Oral Word Association test.Following each task,individuals rated task difficulty and then completed a depression inventory.Performance on these three tests is reflective of neuropsychological status in relation to glucose control.Blood glucose levels were measured immediately prior to and after completing the neuropsychological battery using a glucose meter.Hb A1 c levels were obtained from medical records.Academic performance was based on self-reported grades in Math,Science,and English.Data was analyzed using multiple regression models to evaluate the associations between academic performance,perception of task difficulty,and glucose control.RESULTS:Perceptions of difficulty on a neuropsychological battery significantly predicted academic performance after accounting for glucose control and depression.Perceptions of difficulty on the neuropsychological tests were inversely correlated with academic performance(r =-0.48),while acute(blood glucose) and long-term glucose levels increased along with perceptions of task difficulty(r = 0.47).Additionally,higher depression scores were associatedwith poorer academic performance(r =-0.43).With the first regression analysis,perception of difficulty on the neuropsychological tasks contributed to 8% of the variance in academic performance after controlling for peripheral blood glucose and depression.In the second regression analysis,perception of difficulty accounted for 11% of the variance after accounting for academic performance and depression.The final regression analysis indicated that perception of difficulty increased with peripheral blood glucose,contributing to 22% of the variance.Most importantly,after controlling for perceptions of task difficulty,academic performance no longer predicted glucose levels.Finally,subjects who found the cognitive battery difficult were likely to have poor academic grades.CONCLUSION:Perceptions of difficulty on neurological tests exhibited a significant association with academic achievement,indicating that deficits in this skill may lead to academic disadvantage in diabetic patients.
文摘Pygmalion Effect refers to the expectation from teachers have stimulative effects on students' learning. English educa-tion of junior middle school has its unique nature, and the phenomenon of having trouble in learning English in middle school stu-dents exists generally. So, the key point of this research is how the students use Pygmalion Effect to improve their English Learn-ing.
文摘The difficulty of extracting hidden information, which is essentially a kind of secrecy, is analyzed by information-theoretic method. The relations between key rate, message rate, hiding capacity and difficulty of extraction are studied in the terms of unicity distance of stego-key, and the theoretic conclusion is used to analyze the actual extracting attack on Least Significant Bit(LSB) steganographic algorithms.
文摘Distinguishing the difficulty degree of top coal caving was a precondition of the popularization and application of the roadway sub-level caving in steep seam. Because of complexity and uncertainty of the coal seam, the expression of influence factors was diffi-culty with exact data. According to the fuzzy and uncertainty of influence factors, triangular fuzzy membership functions were adopted to carry out the factors ambiguity, of which the factors not only have the consistency of semantic meaning, but also dissolve sufficiently expert knowledge. Based on the properties and structures of fasART fuzzy neural net-works of fuzzy logic system and practical needs, a simplified fasART model was put for-ward, stability and reliability of the network were improved, the deficiency of learning sam-ples and uncertainty of the factors were better treated. The method is of effective and practical value was identified by experiments.
基金Science and Technology Commission of Shanghai Municipality(14411969200,10DZ2272200,09DZ2200900,10PJ1407500,10PJ1403500,10231203903,10JC1411200)Ministry of Education of China(NCET program)+4 种基金National Natural Science Foundation of China(81000592,11001084)Shanghai Municipal Education Commission(11ZZ103)Shanghai Municipal Health Bureau(2010004)Morning Star Rewarding Fund of Shanghai Jiao Tong University(Category B,2011)New Bairen Plan of Shanghai Jiao Tong University School of Medicine,and Shanghai Health Municipal Bureau Three-year Action(GWⅢ-27.3)
文摘Objective To identify the target behavior in the process of behavioral intervention for children with feeding difficulty and relevant factors that may contribute to more effective intervention.Methods Children aged from 1 to 6 years with feeding difficulty randomly received interactive behavioral intervention(245 cases)or routine primary care(217 cases).By the end of the 1,3,6,and 9 months,the rating score of feeding difficulty and the body mass index(BMI)were assessed.The target behavior was determined based on the selecting criteria that simultaneously satisfied two conditions:①it was relevant to improving children's nutritional status;②it changed fast during intervention.Moreover,the relevant factors of target behavior were analyzed by multivariate analysis(Multi-Way ANOVA).Results Among nine behaviors of feeding difficulty,"eating slowly"was identified as a target behavior because it was closely relevant to the BMI z-score increment and had the biggest score reduction at early stage during intervention.Various factors were relevant to improving the target behavior,including parents acting as caregivers,caregiver's education level equal to and above junior college,and caregiver's concern about their children's feeding difficulty.Conclusion"Eating slowly"should be selected as the target behavior for early intervention for children with feeding difficulty and some social factors should be considered for optimizing the intervention.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT&Future Planning,No.2012R1A1B4003477
文摘Transcranial direct current stimulation(t DCS), an emerging technique for non-invasive brain stimulation, is increasingly used to induce changes in cortical excitability and modulate motor behavior, especially for upper limbs. The purpose of this study was to investigate the effects of t DCS of the primary motor cortex on visuomotor coordination based on three levels of task difficulty in healthy subjects. Thirty-eight healthy participants underwent real t DCS or sham t DCS. Using a single-blind, sham-controlled crossover design, t DCS was applied to the primary motor cortex. For real t DCS conditions, t DCS intensity was 1 m A while stimulation was applied for 15 minutes. For the sham t DCS, electrodes were placed in the same position, but the stimulator was turned off after 5 seconds. Visuomotor tracking task, consisting of three levels(levels 1, 2, 3) of difficulty with higher level indicating greater difficulty, was performed before and after t DCS application. At level 2, real t DCS of the primary motor cortex improved the accurate index compared to the sham t DCS. However, at levels 1 and 3, the accurate index was not significantly increased after real t DCS compared to the sham t DCS. These findings suggest that tasks of moderate difficulty may improve visuomotor coordination in healthy subjects when t DCS is applied compared with easier or more difficult tasks.
文摘Introduction: The use of foods containing high levels of sugar is increasing all the time. This is a risk factor for increased incidence of type 2 diabetes. There are few studies that have investigated the availability of low-sugar müsli products in grocery stores. Purpose: The study aims to identify which types of müsli contain high respectively low levels of sugar, and which brands are involved. Methods: The material consists of both qualitative interviews and observations from five grocery stores: City Gross, Hemköp, Ica Maxi, Stora Coop and Willy’s in Helsingborg, Sweden. The qualitative interviews had a semi-structured character and were recorded. The interviews took approx. 20 minutes and a textual analysis was conducted of the results. Data from observation was analyzed based on brand, nutritional composition and flavors, and also, where low sugar products were placed on store shelves. Results: The grocery stores provided together brands from AXA, Coop, Finax, Frebaco, Garant, ICA, Risenta, Saltå Kvarn och Urtekram, in total 24 müsli products. Of these products, 19 were high in sugar. The observation reveals that müsli products with high sugar content (17 - 29 g per 100 g müsli) are more prominently displayed than those with low sugar content. From the interviews with the store managers, it became clear that it would be valuable to highlight healthy müsli products on the shelves. However, central bureaucracy puts obstacles to such measures. Discussion: The study emphasizes the need for increased visibility of low-sugar products and proposes solutions such as negotiating with responsible person at the head office in Stockholm. Several reviews have shown that if the grocery store raises the prices of unhealthy food, the consumer is willing to purchase healthier müsli and other products. Conclusion: This study shows the need for grocery stores to upgrade healthy müsli products along with advertising to be able to influence customer’s shopping habits. Also, further research is needed how type 2 diabetes is affected by high intakes of food products with high sugar content.
