Objective To identify risk factors contributing to prolonged postoperative length of stay(LOS)in very elderly patients following hip fracture surgery,with a focus on postoperative complications and the impact of diffe...Objective To identify risk factors contributing to prolonged postoperative length of stay(LOS)in very elderly patients following hip fracture surgery,with a focus on postoperative complications and the impact of different anesthesia approaches.Methods This retrospective single-center cohort study enrolled patients aged 90 years or older who underwent hip fracture surgery at Peking Union Medical College Hospital between January 31,2013 and December 31,2023.Relevant perioperative data were collected.The primary outcome was postoperative LOS,and the study cohort was divided into two groups:postoperative LOS≤7 days and LOS>7 days.Logistic regression was performed to identify factors related to prolonged postoperative LOS.Results A total of 155 patients were included.The average age was 92.7±2.6 years.There were 73(47%)patients with postoperative LOS>7 days.Postoperative pneumonia was the only factor associated with a prolonged postoperative LOS(OR=2.12,95%CI[1.09,4.16],P=0.028).Neither the type of anesthesia(regional vs.general anesthesia,OR=1.00,95%CI[0.53,1.90],P=0.993)nor the method of airway management(laryngeal mask ventilation vs.spontaneous breathing,OR=1.46,95%CI[0.58,3.76],P=0.424;endotracheal intubation vs.spontaneous breathing,OR=0.82,95%CI[0.39,1.69],P=0.592)showed a significant association with a prolonged postoperative LOS.Preoperative chronic obstructive pulmonary disease(OR=2.78,95%CI[1.05,7.65],P=0.040)and preoperative neutrophil count(OR=1.13,95%CI[1.01,1.26],P=0.029)were both significantly associated with the occurrence of postoperative pneumonia,while anesthesia type and airway management method were not.Conclusions Postoperative pneumonia was associated with prolonged postoperative LOS in very elderly patients undergoing hip fracture surgery,whereas anesthesia types and airway management methods show no association with prolonged postoperative LOS or postoperative pneumonia.Preoperative comorbidities,especially respiratory conditions and systemic inflammation,potentially play a substantial role in postoperative recovery.展开更多
BACKGROUND:This study aimed to develop and validate a nomogram to estimate the probability of prolonged intensive care unit(ICU)stays.METHODS:Pediatric patients who underwent cardiac surgery were included,with data co...BACKGROUND:This study aimed to develop and validate a nomogram to estimate the probability of prolonged intensive care unit(ICU)stays.METHODS:Pediatric patients who underwent cardiac surgery were included,with data collected from the pediatric intensive care database.The datasets were randomly divided into a training set(75%)and a testing set(25%).A nomogram model was developed to predict prolonged ICU stays in the training set and then validated in the testing set.RESULTS:A total of 795 patients and 266 patients were assigned to the training and testing sets,respectively,with consistent variables.The nomogram developed from the training set included eight characteristics:age,systolic blood pressure,respiratory rate,bicarbonate,direct bilirubin,high-sensitivity C-reactive protein,international normalized ratio,and operation time.The area under the curve values of the nomogram in the training and testing sets were 0.812 and 0.736,respectively.The nomogram demonstrated excellent discrimination and calibration.Decision curve analysis showed that the use of the nomogram resulted in more favorable outcomes compared with the strategies of treating all or none of the patients.CONCLUSION:This study presents a nomogram that may enable early identification of high-risk patients and facilitates tailored postoperative care and better outcomes after pediatric cardiac surgery.展开更多
BACKGROUND:The problem of prolonged emergency department length of stay(EDLOS) is becoming increasingly crucial.This study aims to develop a machine learning(ML) model to predict EDLOS,with EDLOS as the outcome variab...BACKGROUND:The problem of prolonged emergency department length of stay(EDLOS) is becoming increasingly crucial.This study aims to develop a machine learning(ML) model to predict EDLOS,with EDLOS as the outcome variable and demographic characteristics,triage level,and medical resource utilization as predictive factors.METHODS:A retrospective analysis was performed on the patients who visited the emergency department of the Second Affiliated Hospital of Guangzhou Medical University from March 2019to September 2021,and a total of 321,012 cases were identified.According to the inclusion and exclusion criteria,187,028 cases were finally included in the analysis.ML analysis was performed using R-squared(R^(2)),and the predictive factors and the EDLOS were used as independent variables and dependent variables,respectively,to establish models.The performance evaluation of the ML models was conducted through the utilization of the mean absolute error(MAE),root mean square error(RMSE),and R^(2),enabling an objective comparative analysis.RESULTS:In the comparative analysis of the six ML models,light gradient boosting machine(LightGBM) model demonstrated the lowest MAE(443.519) and RMSE(826.783),and the highest R^(2) value(0.48),indicating better model fit and predictive performance.Among the top 10 predictive factors associated with EDLOS according to the LightGBM model,the emergency waiting time,age,and emergency arrival time had the most significant impact on the EDLOS.CONCLUSION:The LightGBM model suggests that the emergency waiting time,age,and emergency arrival time may be used to predict the EDLOS.展开更多
Against the backdrop of the strategies for rural revitalization and the integration of agriculture,culture,and tourism,farm stay,as a vital carrier,requires a systematic analysis of its resource integration effectiven...Against the backdrop of the strategies for rural revitalization and the integration of agriculture,culture,and tourism,farm stay,as a vital carrier,requires a systematic analysis of its resource integration effectiveness and the actual needs of tourists.Taking Chongqing City as an example,this study leverages tourist reviews from the Dianping platform(China’s leading consumer review site)and employs a combination of TF-IDF keyword extraction,SnowNLP sentiment analysis,and LDA topic modeling to dissect tourists’perception characteristics and latent demands for agritourism resources from the demand side.The findings reveal that agricultural and tourism elements garner significant attention,while cultural resources are notably underperceived,indicating an imbalanced integration structure.Sentiment is predominantly positive,yet negative feedback highlights issues in service management,transportation,and homogenized experiences.Latent demands converge on three dimensions:deepening agricultural experiences,enhancing cultural participation and interaction,and improving environmental and service quality.Based on these findings,this study proposes integration enhancement strategies,including agricultural branding,cultural vitalization,service intelligence,and multi-faceted collaboration,to drive experience upgrades and sustainable development in farm stays,offering theoretical references and practical pathways for rural tourism integration in similar regions.展开更多
BACKGROUND Critically ill patients often present on admission or develop acute respiratory failure requiring intubation and application of positive pressure ventilation during their hospital stay.AIM To investigate an...BACKGROUND Critically ill patients often present on admission or develop acute respiratory failure requiring intubation and application of positive pressure ventilation during their hospital stay.AIM To investigate and identify the epidemiological data,parameters associated with respiratory settings or the mechanics,and values related to arterial blood gases(ABGs)that are associated with outcomes in critically ill patients.METHODS A retrospective analysis of 131 patients[mean age,67.3 years;mean acute physiology and chronic health evaluation(APACHE)score,21.4]with acute respiratory failure requiring invasive mechanical ventilation was performed.The parameters that were statistically analyzed included demographic data,the presence of comorbidities,the presence of coronavirus disease 19(COVID-19),the respiratory rate(RR),peak airway pressure(Ppeak),minute ventilation(MV),positive endexpiratory pressure,and the values related to ABGs.In order to facilitate the statistical analysis,patients were evaluated and compared in groups:Survivors(n=41)vs non-survivors(n=90)and patients without acute kidney injury(AKI)(n=60)vs patients with AKI(n=71).Four endpoints were studied:Mortality,length of stay,duration of mechanical ventilation,and AKI.Group comparisons were performed using the following statistical tests:Theχ^(2) test with Yates’correction,Fisher’s exact test,the Mann-Whitney U test,and Spearman’s rank correlation analysis.Binary logistic regression analysis conducted after the univariate statistical tests facilitated the investigation of the independent predictors of mortality and AKI.A two-sided P value of less than 0.05 was considered the threshold of statistical significance.RESULTS Non-survivors presented statistically significant differences in terms of being older in age,the presence of comorbidities,elevated APACHE score,medical(vs surgical)reasons for admission,presence of COVID-19,lower pH at ABGs,lower values of the oxygenation ratio(arterial oxygen partial pressure to the fraction of inspired oxygen)and arterial oxygen partial pressure,and elevated values of Ppeak,positive end-expiratory pressure,RR,arterial carbon dioxide partial pressure,and MV.The factors identified as independent predictors of mortality were the presence of comorbidities,APACHE score,COVID-19 status,arterial carbon dioxide partial pressure,Ppeak,RR,and MV.COVID-19 presence and elevated values of RR and Ppeak were positively correlated with the other three endpoints(length of stay,the duration of mechanical ventilation in survivors,and the occurrence of AKI in the entire study population)that were studied.The other parameters exhibited a variable(either positive/negative,or no)correlation to the four endpoints under investigation.CONCLUSION Among all investigated outcome measures,COVID-19,Ppeak,and RR were strongly associated with all the endpoints studied,suggesting that proper interventions involving the modifiable respiratory parameters Ppeak and RR could improve the overall outcome in these patients.A novel finding of this study was the relationship between RR and AKI,which is worthy of further investigation.Future studies may explore the clinical interpretation of these findings to improve outcomes in critically ill patients with acute respiratory failure.展开更多
Background The number of transcatheter aortic valve implantation(TAVI)procedures in patients with severe aortic stenosis(AS)is increasing worldwide.We aimed to assess the impact of a TAVI program on clinical profile,m...Background The number of transcatheter aortic valve implantation(TAVI)procedures in patients with severe aortic stenosis(AS)is increasing worldwide.We aimed to assess the impact of a TAVI program on clinical profile,management and outcomes of these patients and to describe predictors of length of hospital stay(LoS)in this context.Methods Retrospective single center study enrolling consecutive AS patients undergoing TAVI and surviving to discharge(January 2018-December 2022).A TAVI program was implemented in may 2021.Baseline clinical characteristics,management and in-hospital complications were registered.Predictors of long hospital stay(>7 day)were assessed by binary logistic regression.Results We included 614 patients,with mean age 80.5 years.Most patients(438/614,71.2%)presented conditions that precluded an early discharge.Mean hospital stay was 7.6 days.Patients admitted after the implementation of the program had a significantly lower burden of comorbidities.The rate of conduction disturbances after TAVI remained stable around 60%.However,permanent pacemaker requirement declined from 30.3%to 22.5%(P=0.028).LoS was reduced after the implementation of the program both in patients suitable for an early discharge(from 6.5 day to 4 day,P<0.001)and unsuitable patients(from 9.4 day to 7.7 day,P=0.014).The final predictive model for LoS included prior pacemaker and availability of TAVI program as protectors and other valvular diseases,day of the week,emergent procedures,and conduction disturbances and other complications as independent predictors of long stay after TAVI.Conclusions Most patients undergoing TAVI present conditions that preclude an early hospital discharge.The implementation of a TAVI program improved selection of patients,with a lower burden of comorbidities,a lower rate of complications and a marked reduction of hospital stay.展开更多
This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use...This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use of inclined cables;however,the international standards for bridge design stipulate different safety factors for stay cables of both types of bridges.To address this misconception,a comparative study was carried out on the safety factors of stay cables under fatigue and ultimate limit states by considering the effects of various untoward and damaging factors,such as overloading,cable loss,and corrosion.The primary goal of this study is to describe the structural disparities between both types of bridges and evaluate their structural redundancies by employing deterministic and nondeterministic methods.To achieve this goal,three-dimensional finite-element models of both bridges were developed based on the current design guidelines for stay cables in Japan.After the balanced states of the bridge models were achieved,static analyses were performed for different safety factors of stay cables in a parametric manner.Finally,the first-order reliability method and Monte Carlo method were applied to determine the reliability index of stay cables.The analysis results show that cable-stayed and extradosed bridges exhibit different structural redundancies for different safety factors under the same loading conditions.Moreover,a significant increase in structural redundancy occurs with an incremental increase in the safety factors of stay cables.展开更多
This paper presents a nonlinear dynamic model for simulation and analysis of a kind of parametrically excited vibration of stay cable caused by support motion in cable-stayed bridges. The sag, inclination angle of the...This paper presents a nonlinear dynamic model for simulation and analysis of a kind of parametrically excited vibration of stay cable caused by support motion in cable-stayed bridges. The sag, inclination angle of the stay cable are considered in the model, based on which, the oscillation mechanism and dynamic response characteristics of this kind of vibration are analyzed through numerical calculation. It is noted that parametrically excited oscillation of a stay cable with certain sag, inclination angle and initial static tension force may occur in cable-stayed bridges due to deck vibration under the condition that the natural frequency of a cable approaches to about half of the first model frequency of the bridge deck system. A new vibration control system installed on the cable anchorage is proposed as a possible damping system to suppress the cable parametric oscillation. The numerical calculation results showed that with the use of this damping system, the cable oscillation due to the vibration of the deck and/or towers will be considerably reduced.展开更多
[Objective] This study aimed to investigate the effect of water stress on stay green of Yunge F2 generation. [Method] Total 26 sugarcane innovative germplasm materials of Yunge F2 generation, along with their female p...[Objective] This study aimed to investigate the effect of water stress on stay green of Yunge F2 generation. [Method] Total 26 sugarcane innovative germplasm materials of Yunge F2 generation, along with their female parent, were selected as the experimental materials. Based on the observation on appearance of stray green and other five physiological and biochemical indexes, the drought resis- tance of the experimental materials was evaluated comprehensively by subordinate function method, grey relational analysis, and cluster analysis. [Result] The rank of drought resistance of the experimental materials was not exactly the same between subordinate function method and grey relational analysis. However, the drought .re- sistance evaluation results by isometric range-based cluster analysis were consistent with those by the two foregoing methods except Yunge F2 11-68 and Yunge F1 11- 254. At the Euclidean distance of 2.00, the tested materials were classified into four groups. The first group included 8 drought-strongly resistant materials, the third group included 6 drought-moderately resistant materials, the fourth group included 3 drought-poorly resistant materials, and the second group included drought-strongly resistant and drought-moderately resistant materials. The drought resistance coeffi- cients of green leaf numberLtotal leaf number and top four leaves chlorophyll content showed significantly positive correlation with drought resistance comprehensive eval- uation value, thus green leaf number/total leaf number and top four leaves chloro- phyll content could be used as the evaluation indexes of drought resistance in sug- arcane. [Conclusion] The excellent materials possess strong drought resistance and good green holding performance, such as Yunge F2 11-159, can be used as crucial parents and basic germplasm materials in drought resistance breeding of sugarcane. 7展开更多
Along with the expanding of span of cable-stayed bridge,wind load becomes a more and more important controlling factor for bridge the design.A very large proportion of the wind load acting on cables has exceeded that ...Along with the expanding of span of cable-stayed bridge,wind load becomes a more and more important controlling factor for bridge the design.A very large proportion of the wind load acting on cables has exceeded that acting on deck.There was not any detailed prescript in Chinese code for calculation of longitudinal wind load on cables due to lack of theoretical research and experiment,and conservative simplified calculation was adopted during design,which leads to conservative and uneconomical design of structures.To resolve this problem,cable force experiment was carried out during the design of Sutong Bridge.By comparing with international research results,the calculation formula of longitudinal wind drag coefficient for cables was advanced to fill the blank of bridge wind resistant code of China,and has already been adopted in the Highway Bridge Wind Resistant Design Code(JTG/T D60-01-2004)with great significance for bridge engineering.展开更多
According to the conditions to develop Long Stay in small tourism towns,the demonstration of Long Stay in the planning and construction of small towns was taken into consideration,and its benefits for tourism towns we...According to the conditions to develop Long Stay in small tourism towns,the demonstration of Long Stay in the planning and construction of small towns was taken into consideration,and its benefits for tourism towns were analyzed.The results showed that small tourism towns were endowed with sound conditions to develop Long Stay,which played its role in the overall planning of towns and would benefit the economic development of these towns.展开更多
'Farm stay' tourism is a kind of new tourism form in recent years,which can promote regional economic development.The study discusses the existing problems in the setting of tourism products,and puts forward s...'Farm stay' tourism is a kind of new tourism form in recent years,which can promote regional economic development.The study discusses the existing problems in the setting of tourism products,and puts forward some countermeasures for the development of 'farm stay' tourism in Yanan city.展开更多
Shoppers typically want to spend an amount of time at a destination that is proportional to the travel time required to arrive there;thus,the travel time can be considered the cost of their trip.This is likely to be t...Shoppers typically want to spend an amount of time at a destination that is proportional to the travel time required to arrive there;thus,the travel time can be considered the cost of their trip.This is likely to be the case across regions with different urban structures and cultures.The purpose of this study was therefore to analyze the shopping behaviors contained in travel survey data from three metropolitan areas in Japan to identify common patterns and indicators based on travel time and stay time,thereby obtaining an understanding to inform future trade area analyses.Both the travel time and stay time associated with shopping behavior were found to be log-normally distributed regardless of metropolitan area,and four shopping behavior patterns common among the metropolitan areas were identified.The“stay coeffi-cient”was then defined to express the elasticity of stay time according to travel time,and its values were similar according to shopping behavior pattern regardless of metropolitan area.The stay coefficient proposed in this study can therefore be applied to identify shopping behavior patterns in any urban area based on the relationship between travel time and stay time,realizing a novel approach to the analysis of and marketing for trade areas when planning the construction or renovation of commercial facilities.This approach can help inform the decisions of urban policy makers,marketing advisors,and commercial facility operators,and should be of interest to researchers and practitioners working with geospatial,shopping,and other human behavioral characteristics.展开更多
Nonlinear vibration can cause serious problems in long span cable-stayed bridges.When the internal resonance threshold is reached between the excitation frequency and natural frequency,large amplitudes occur in the ca...Nonlinear vibration can cause serious problems in long span cable-stayed bridges.When the internal resonance threshold is reached between the excitation frequency and natural frequency,large amplitudes occur in the cable.Based on the current situation of lacking corresponding constraint criteria,a model was presented for analyzing the dynamic reliability of coupling oscillation between the cable and tower in a cable-stayed bridge.First of all,in the case of cable sag,the d'Alembert principle is applied to studying the nonlinear dynamic behavior of the structure,and resonance failure interval of parametric oscillation is calculated accordingly.Then the dynamic reliability model is set up using the JC method.An application of this model has been developed for the preliminary design of one cable-stayed bridge located on Hai River in Tianjin,and time histories analysis as well as reliability indexes have been obtained.When frequency ratio between the cable and tower is approaching 1∶2,the reliability index is 0.98,indicating high failure probability.And this is consistent with theoretical derivation and experimental results in reference.This model,which is capable of computing the reliability index of resonance failure,provides theoretical basis for the establishment of corresponding rule.展开更多
Cable-stayed bridge is a kind of bridge under bending pressure and tension of supporting system. The main stressed component of this kind of bridge is stay cable, which plays a vital role in the whole bridge structure...Cable-stayed bridge is a kind of bridge under bending pressure and tension of supporting system. The main stressed component of this kind of bridge is stay cable, which plays a vital role in the whole bridge structure. Based on this, this paper takes the D1 cable-stayed bridge project of Malaysia Coastal Avenue as an example to deeply explore the construction technology of parallel steel cable stayed cables of long-span cable-stayed bridges, aiming at providing scientific construction technology support for the construction of cable-stayed bridges and ensuring the quality of bridge construction.展开更多
Landing gear lower drag stay is a key component which connects fuselage and landing gear and directly effects the safety and performance of aircraft takeoff and landing. To effectively design the lower drag stay and r...Landing gear lower drag stay is a key component which connects fuselage and landing gear and directly effects the safety and performance of aircraft takeoff and landing. To effectively design the lower drag stay and reduce the weight of landing gear, Global/local Linked Driven Optimization Strategy(GLDOS) was developed to conduct the overall process design of lower drag stay in respect of optimization thought. The whole-process optimization involves two stages of structural conceptual design and detailed design. In the structural conceptual design, the landing gear lower drag stay was globally topologically optimized by adopting multiple starting points algorithm. In the detailed design, the local size and shape of landing gear lower drag stay were globally optimized by the gradient optimization strategy. The GLDOS method adopts different optimization strategies for different optimization stages to acquire the optimum design effect. Through the experimental validation, the weight of the optimized lower dray stay with the developed GLDOS is reduced by 16.79% while keeping enough strength and stiffness, which satisfies the requirements of engineering design under the typical loading conditions. The proposed GLDOS is validated to be accurate and efficient in optimization scheme and design cycles. The efforts of this paper provide a whole-process optimization approach regarding different optimization technologies in different design phases, which is significant in reducing structural weight and enhance design tp wid 1 precision for complex structures in aircrafts.展开更多
文摘Objective To identify risk factors contributing to prolonged postoperative length of stay(LOS)in very elderly patients following hip fracture surgery,with a focus on postoperative complications and the impact of different anesthesia approaches.Methods This retrospective single-center cohort study enrolled patients aged 90 years or older who underwent hip fracture surgery at Peking Union Medical College Hospital between January 31,2013 and December 31,2023.Relevant perioperative data were collected.The primary outcome was postoperative LOS,and the study cohort was divided into two groups:postoperative LOS≤7 days and LOS>7 days.Logistic regression was performed to identify factors related to prolonged postoperative LOS.Results A total of 155 patients were included.The average age was 92.7±2.6 years.There were 73(47%)patients with postoperative LOS>7 days.Postoperative pneumonia was the only factor associated with a prolonged postoperative LOS(OR=2.12,95%CI[1.09,4.16],P=0.028).Neither the type of anesthesia(regional vs.general anesthesia,OR=1.00,95%CI[0.53,1.90],P=0.993)nor the method of airway management(laryngeal mask ventilation vs.spontaneous breathing,OR=1.46,95%CI[0.58,3.76],P=0.424;endotracheal intubation vs.spontaneous breathing,OR=0.82,95%CI[0.39,1.69],P=0.592)showed a significant association with a prolonged postoperative LOS.Preoperative chronic obstructive pulmonary disease(OR=2.78,95%CI[1.05,7.65],P=0.040)and preoperative neutrophil count(OR=1.13,95%CI[1.01,1.26],P=0.029)were both significantly associated with the occurrence of postoperative pneumonia,while anesthesia type and airway management method were not.Conclusions Postoperative pneumonia was associated with prolonged postoperative LOS in very elderly patients undergoing hip fracture surgery,whereas anesthesia types and airway management methods show no association with prolonged postoperative LOS or postoperative pneumonia.Preoperative comorbidities,especially respiratory conditions and systemic inflammation,potentially play a substantial role in postoperative recovery.
基金supported by the National Natural Science Foundation of China(82230074,81971809 and 82372159)the Liangshan Prefecture Science and Technology Plan Project(23ZDYF0180 and 24YYYJ0043).
文摘BACKGROUND:This study aimed to develop and validate a nomogram to estimate the probability of prolonged intensive care unit(ICU)stays.METHODS:Pediatric patients who underwent cardiac surgery were included,with data collected from the pediatric intensive care database.The datasets were randomly divided into a training set(75%)and a testing set(25%).A nomogram model was developed to predict prolonged ICU stays in the training set and then validated in the testing set.RESULTS:A total of 795 patients and 266 patients were assigned to the training and testing sets,respectively,with consistent variables.The nomogram developed from the training set included eight characteristics:age,systolic blood pressure,respiratory rate,bicarbonate,direct bilirubin,high-sensitivity C-reactive protein,international normalized ratio,and operation time.The area under the curve values of the nomogram in the training and testing sets were 0.812 and 0.736,respectively.The nomogram demonstrated excellent discrimination and calibration.Decision curve analysis showed that the use of the nomogram resulted in more favorable outcomes compared with the strategies of treating all or none of the patients.CONCLUSION:This study presents a nomogram that may enable early identification of high-risk patients and facilitates tailored postoperative care and better outcomes after pediatric cardiac surgery.
基金supported by Guangzhou Municipal Health Science and Technology General Program (20221A011083)the Key Medical Disciplines and Specialties Program of Guangzhou(2021-2023)Guangdong University Innovation Team Project(2024KCXTD029)。
文摘BACKGROUND:The problem of prolonged emergency department length of stay(EDLOS) is becoming increasingly crucial.This study aims to develop a machine learning(ML) model to predict EDLOS,with EDLOS as the outcome variable and demographic characteristics,triage level,and medical resource utilization as predictive factors.METHODS:A retrospective analysis was performed on the patients who visited the emergency department of the Second Affiliated Hospital of Guangzhou Medical University from March 2019to September 2021,and a total of 321,012 cases were identified.According to the inclusion and exclusion criteria,187,028 cases were finally included in the analysis.ML analysis was performed using R-squared(R^(2)),and the predictive factors and the EDLOS were used as independent variables and dependent variables,respectively,to establish models.The performance evaluation of the ML models was conducted through the utilization of the mean absolute error(MAE),root mean square error(RMSE),and R^(2),enabling an objective comparative analysis.RESULTS:In the comparative analysis of the six ML models,light gradient boosting machine(LightGBM) model demonstrated the lowest MAE(443.519) and RMSE(826.783),and the highest R^(2) value(0.48),indicating better model fit and predictive performance.Among the top 10 predictive factors associated with EDLOS according to the LightGBM model,the emergency waiting time,age,and emergency arrival time had the most significant impact on the EDLOS.CONCLUSION:The LightGBM model suggests that the emergency waiting time,age,and emergency arrival time may be used to predict the EDLOS.
基金Chongqing University of Science and Technology Graduate Innovation Program Project(YKJCX2420802)。
文摘Against the backdrop of the strategies for rural revitalization and the integration of agriculture,culture,and tourism,farm stay,as a vital carrier,requires a systematic analysis of its resource integration effectiveness and the actual needs of tourists.Taking Chongqing City as an example,this study leverages tourist reviews from the Dianping platform(China’s leading consumer review site)and employs a combination of TF-IDF keyword extraction,SnowNLP sentiment analysis,and LDA topic modeling to dissect tourists’perception characteristics and latent demands for agritourism resources from the demand side.The findings reveal that agricultural and tourism elements garner significant attention,while cultural resources are notably underperceived,indicating an imbalanced integration structure.Sentiment is predominantly positive,yet negative feedback highlights issues in service management,transportation,and homogenized experiences.Latent demands converge on three dimensions:deepening agricultural experiences,enhancing cultural participation and interaction,and improving environmental and service quality.Based on these findings,this study proposes integration enhancement strategies,including agricultural branding,cultural vitalization,service intelligence,and multi-faceted collaboration,to drive experience upgrades and sustainable development in farm stays,offering theoretical references and practical pathways for rural tourism integration in similar regions.
文摘BACKGROUND Critically ill patients often present on admission or develop acute respiratory failure requiring intubation and application of positive pressure ventilation during their hospital stay.AIM To investigate and identify the epidemiological data,parameters associated with respiratory settings or the mechanics,and values related to arterial blood gases(ABGs)that are associated with outcomes in critically ill patients.METHODS A retrospective analysis of 131 patients[mean age,67.3 years;mean acute physiology and chronic health evaluation(APACHE)score,21.4]with acute respiratory failure requiring invasive mechanical ventilation was performed.The parameters that were statistically analyzed included demographic data,the presence of comorbidities,the presence of coronavirus disease 19(COVID-19),the respiratory rate(RR),peak airway pressure(Ppeak),minute ventilation(MV),positive endexpiratory pressure,and the values related to ABGs.In order to facilitate the statistical analysis,patients were evaluated and compared in groups:Survivors(n=41)vs non-survivors(n=90)and patients without acute kidney injury(AKI)(n=60)vs patients with AKI(n=71).Four endpoints were studied:Mortality,length of stay,duration of mechanical ventilation,and AKI.Group comparisons were performed using the following statistical tests:Theχ^(2) test with Yates’correction,Fisher’s exact test,the Mann-Whitney U test,and Spearman’s rank correlation analysis.Binary logistic regression analysis conducted after the univariate statistical tests facilitated the investigation of the independent predictors of mortality and AKI.A two-sided P value of less than 0.05 was considered the threshold of statistical significance.RESULTS Non-survivors presented statistically significant differences in terms of being older in age,the presence of comorbidities,elevated APACHE score,medical(vs surgical)reasons for admission,presence of COVID-19,lower pH at ABGs,lower values of the oxygenation ratio(arterial oxygen partial pressure to the fraction of inspired oxygen)and arterial oxygen partial pressure,and elevated values of Ppeak,positive end-expiratory pressure,RR,arterial carbon dioxide partial pressure,and MV.The factors identified as independent predictors of mortality were the presence of comorbidities,APACHE score,COVID-19 status,arterial carbon dioxide partial pressure,Ppeak,RR,and MV.COVID-19 presence and elevated values of RR and Ppeak were positively correlated with the other three endpoints(length of stay,the duration of mechanical ventilation in survivors,and the occurrence of AKI in the entire study population)that were studied.The other parameters exhibited a variable(either positive/negative,or no)correlation to the four endpoints under investigation.CONCLUSION Among all investigated outcome measures,COVID-19,Ppeak,and RR were strongly associated with all the endpoints studied,suggesting that proper interventions involving the modifiable respiratory parameters Ppeak and RR could improve the overall outcome in these patients.A novel finding of this study was the relationship between RR and AKI,which is worthy of further investigation.Future studies may explore the clinical interpretation of these findings to improve outcomes in critically ill patients with acute respiratory failure.
文摘Background The number of transcatheter aortic valve implantation(TAVI)procedures in patients with severe aortic stenosis(AS)is increasing worldwide.We aimed to assess the impact of a TAVI program on clinical profile,management and outcomes of these patients and to describe predictors of length of hospital stay(LoS)in this context.Methods Retrospective single center study enrolling consecutive AS patients undergoing TAVI and surviving to discharge(January 2018-December 2022).A TAVI program was implemented in may 2021.Baseline clinical characteristics,management and in-hospital complications were registered.Predictors of long hospital stay(>7 day)were assessed by binary logistic regression.Results We included 614 patients,with mean age 80.5 years.Most patients(438/614,71.2%)presented conditions that precluded an early discharge.Mean hospital stay was 7.6 days.Patients admitted after the implementation of the program had a significantly lower burden of comorbidities.The rate of conduction disturbances after TAVI remained stable around 60%.However,permanent pacemaker requirement declined from 30.3%to 22.5%(P=0.028).LoS was reduced after the implementation of the program both in patients suitable for an early discharge(from 6.5 day to 4 day,P<0.001)and unsuitable patients(from 9.4 day to 7.7 day,P=0.014).The final predictive model for LoS included prior pacemaker and availability of TAVI program as protectors and other valvular diseases,day of the week,emergent procedures,and conduction disturbances and other complications as independent predictors of long stay after TAVI.Conclusions Most patients undergoing TAVI present conditions that preclude an early hospital discharge.The implementation of a TAVI program improved selection of patients,with a lower burden of comorbidities,a lower rate of complications and a marked reduction of hospital stay.
文摘This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use of inclined cables;however,the international standards for bridge design stipulate different safety factors for stay cables of both types of bridges.To address this misconception,a comparative study was carried out on the safety factors of stay cables under fatigue and ultimate limit states by considering the effects of various untoward and damaging factors,such as overloading,cable loss,and corrosion.The primary goal of this study is to describe the structural disparities between both types of bridges and evaluate their structural redundancies by employing deterministic and nondeterministic methods.To achieve this goal,three-dimensional finite-element models of both bridges were developed based on the current design guidelines for stay cables in Japan.After the balanced states of the bridge models were achieved,static analyses were performed for different safety factors of stay cables in a parametric manner.Finally,the first-order reliability method and Monte Carlo method were applied to determine the reliability index of stay cables.The analysis results show that cable-stayed and extradosed bridges exhibit different structural redundancies for different safety factors under the same loading conditions.Moreover,a significant increase in structural redundancy occurs with an incremental increase in the safety factors of stay cables.
文摘This paper presents a nonlinear dynamic model for simulation and analysis of a kind of parametrically excited vibration of stay cable caused by support motion in cable-stayed bridges. The sag, inclination angle of the stay cable are considered in the model, based on which, the oscillation mechanism and dynamic response characteristics of this kind of vibration are analyzed through numerical calculation. It is noted that parametrically excited oscillation of a stay cable with certain sag, inclination angle and initial static tension force may occur in cable-stayed bridges due to deck vibration under the condition that the natural frequency of a cable approaches to about half of the first model frequency of the bridge deck system. A new vibration control system installed on the cable anchorage is proposed as a possible damping system to suppress the cable parametric oscillation. The numerical calculation results showed that with the use of this damping system, the cable oscillation due to the vibration of the deck and/or towers will be considerably reduced.
基金Supported by National Natural Science Foundation of China(31360358)Key Project of Yunnan Province(2015FA034)Yunnan Provincial Science and Technology Plan Benefiting the People(2014RA059)~~
文摘[Objective] This study aimed to investigate the effect of water stress on stay green of Yunge F2 generation. [Method] Total 26 sugarcane innovative germplasm materials of Yunge F2 generation, along with their female parent, were selected as the experimental materials. Based on the observation on appearance of stray green and other five physiological and biochemical indexes, the drought resis- tance of the experimental materials was evaluated comprehensively by subordinate function method, grey relational analysis, and cluster analysis. [Result] The rank of drought resistance of the experimental materials was not exactly the same between subordinate function method and grey relational analysis. However, the drought .re- sistance evaluation results by isometric range-based cluster analysis were consistent with those by the two foregoing methods except Yunge F2 11-68 and Yunge F1 11- 254. At the Euclidean distance of 2.00, the tested materials were classified into four groups. The first group included 8 drought-strongly resistant materials, the third group included 6 drought-moderately resistant materials, the fourth group included 3 drought-poorly resistant materials, and the second group included drought-strongly resistant and drought-moderately resistant materials. The drought resistance coeffi- cients of green leaf numberLtotal leaf number and top four leaves chlorophyll content showed significantly positive correlation with drought resistance comprehensive eval- uation value, thus green leaf number/total leaf number and top four leaves chloro- phyll content could be used as the evaluation indexes of drought resistance in sug- arcane. [Conclusion] The excellent materials possess strong drought resistance and good green holding performance, such as Yunge F2 11-159, can be used as crucial parents and basic germplasm materials in drought resistance breeding of sugarcane. 7
基金National Science and Technology Support Program of China(No.2006BAG04B01)
文摘Along with the expanding of span of cable-stayed bridge,wind load becomes a more and more important controlling factor for bridge the design.A very large proportion of the wind load acting on cables has exceeded that acting on deck.There was not any detailed prescript in Chinese code for calculation of longitudinal wind load on cables due to lack of theoretical research and experiment,and conservative simplified calculation was adopted during design,which leads to conservative and uneconomical design of structures.To resolve this problem,cable force experiment was carried out during the design of Sutong Bridge.By comparing with international research results,the calculation formula of longitudinal wind drag coefficient for cables was advanced to fill the blank of bridge wind resistant code of China,and has already been adopted in the Highway Bridge Wind Resistant Design Code(JTG/T D60-01-2004)with great significance for bridge engineering.
文摘According to the conditions to develop Long Stay in small tourism towns,the demonstration of Long Stay in the planning and construction of small towns was taken into consideration,and its benefits for tourism towns were analyzed.The results showed that small tourism towns were endowed with sound conditions to develop Long Stay,which played its role in the overall planning of towns and would benefit the economic development of these towns.
文摘'Farm stay' tourism is a kind of new tourism form in recent years,which can promote regional economic development.The study discusses the existing problems in the setting of tourism products,and puts forward some countermeasures for the development of 'farm stay' tourism in Yanan city.
文摘Shoppers typically want to spend an amount of time at a destination that is proportional to the travel time required to arrive there;thus,the travel time can be considered the cost of their trip.This is likely to be the case across regions with different urban structures and cultures.The purpose of this study was therefore to analyze the shopping behaviors contained in travel survey data from three metropolitan areas in Japan to identify common patterns and indicators based on travel time and stay time,thereby obtaining an understanding to inform future trade area analyses.Both the travel time and stay time associated with shopping behavior were found to be log-normally distributed regardless of metropolitan area,and four shopping behavior patterns common among the metropolitan areas were identified.The“stay coeffi-cient”was then defined to express the elasticity of stay time according to travel time,and its values were similar according to shopping behavior pattern regardless of metropolitan area.The stay coefficient proposed in this study can therefore be applied to identify shopping behavior patterns in any urban area based on the relationship between travel time and stay time,realizing a novel approach to the analysis of and marketing for trade areas when planning the construction or renovation of commercial facilities.This approach can help inform the decisions of urban policy makers,marketing advisors,and commercial facility operators,and should be of interest to researchers and practitioners working with geospatial,shopping,and other human behavioral characteristics.
基金Supported by National Natural Science Foundation of China(No.50579047).
文摘Nonlinear vibration can cause serious problems in long span cable-stayed bridges.When the internal resonance threshold is reached between the excitation frequency and natural frequency,large amplitudes occur in the cable.Based on the current situation of lacking corresponding constraint criteria,a model was presented for analyzing the dynamic reliability of coupling oscillation between the cable and tower in a cable-stayed bridge.First of all,in the case of cable sag,the d'Alembert principle is applied to studying the nonlinear dynamic behavior of the structure,and resonance failure interval of parametric oscillation is calculated accordingly.Then the dynamic reliability model is set up using the JC method.An application of this model has been developed for the preliminary design of one cable-stayed bridge located on Hai River in Tianjin,and time histories analysis as well as reliability indexes have been obtained.When frequency ratio between the cable and tower is approaching 1∶2,the reliability index is 0.98,indicating high failure probability.And this is consistent with theoretical derivation and experimental results in reference.This model,which is capable of computing the reliability index of resonance failure,provides theoretical basis for the establishment of corresponding rule.
文摘Cable-stayed bridge is a kind of bridge under bending pressure and tension of supporting system. The main stressed component of this kind of bridge is stay cable, which plays a vital role in the whole bridge structure. Based on this, this paper takes the D1 cable-stayed bridge project of Malaysia Coastal Avenue as an example to deeply explore the construction technology of parallel steel cable stayed cables of long-span cable-stayed bridges, aiming at providing scientific construction technology support for the construction of cable-stayed bridges and ensuring the quality of bridge construction.
基金co-supported by National Natural Science Foundation of China (Nos. 51975124 and 51675179)Aerospace Science and Technology Fund of China (No.AERO201937)Research Start-up Funding of Fudan University (No. FDU38341)。
文摘Landing gear lower drag stay is a key component which connects fuselage and landing gear and directly effects the safety and performance of aircraft takeoff and landing. To effectively design the lower drag stay and reduce the weight of landing gear, Global/local Linked Driven Optimization Strategy(GLDOS) was developed to conduct the overall process design of lower drag stay in respect of optimization thought. The whole-process optimization involves two stages of structural conceptual design and detailed design. In the structural conceptual design, the landing gear lower drag stay was globally topologically optimized by adopting multiple starting points algorithm. In the detailed design, the local size and shape of landing gear lower drag stay were globally optimized by the gradient optimization strategy. The GLDOS method adopts different optimization strategies for different optimization stages to acquire the optimum design effect. Through the experimental validation, the weight of the optimized lower dray stay with the developed GLDOS is reduced by 16.79% while keeping enough strength and stiffness, which satisfies the requirements of engineering design under the typical loading conditions. The proposed GLDOS is validated to be accurate and efficient in optimization scheme and design cycles. The efforts of this paper provide a whole-process optimization approach regarding different optimization technologies in different design phases, which is significant in reducing structural weight and enhance design tp wid 1 precision for complex structures in aircrafts.
