Abstract: The great majority of the Palaeozoic orogenic belts of Central Asia are of the intercontinental type, whose evolution always follows a five-stage model, i.e. the basal continental crust-extensional transitio...Abstract: The great majority of the Palaeozoic orogenic belts of Central Asia are of the intercontinental type, whose evolution always follows a five-stage model, i.e. the basal continental crust-extensional transitional crust-oceanic crust-convergent transitional crust-new continental crust model. The stage for the extensional transitional crust is a pretty long, independent and inevitable phase. The dismembering mechanism of the basal continental crust becoming an extensional continental crust is delineated by the simple shear model put forward by Wernike (1981). The continental margins on the sides of a gently dipping detachment zone and moving along it are asymmetric: one side is of the nonmagmatic type and the other of the magmatic type with a typical bimodal volcanic formation. In the latter case, however, they were often confused with island arcs. This paper discusses the five-stage process of the crustal evolution of some typical orogenic belts in Xinjiang.展开更多
For the cyclic process of mass transfer in tray columns there are considered the hydrodynamic models of liquid flow during steam supply and during overflow of liquid from tray to tray. During steam supply, the hydrody...For the cyclic process of mass transfer in tray columns there are considered the hydrodynamic models of liquid flow during steam supply and during overflow of liquid from tray to tray. During steam supply, the hydrodynamic model is determined as perfect displacement model, and during liquid overflow, it is described as cell model. There were received the characteristics of liquid flow as follows： average residence time of liquid, degree of dispersion around the mean on the tray, number of perfect mixing cells depending on multiplication factor of exchange of liquid delay. In Y-X coordinates there is depicted a work line and theoretical stage of perfect displacement model. There were considered the conditions of mutual transfer of theoretical stage and theoretical stage with perfect displacement. The advantages of the mass transfer cyclic process to the stationary one arc stated.展开更多
Gelugpa is the most influential extant religious sect of Tibetan Buddhism,which is the spiritual prop for Tibetans,with thousands of monasteries and followers in Tibetan areas of China.Studies on the spatial diffusion...Gelugpa is the most influential extant religious sect of Tibetan Buddhism,which is the spiritual prop for Tibetans,with thousands of monasteries and followers in Tibetan areas of China.Studies on the spatial diffusion processes of Gelugpa can not only reveal its historical geographical development but also lay the foundation for anticipating its future development trend.However,existing studies on Gelugpa lack geographical perspective,making it difficult to explore the spatial characteristics.Furthermore,the prevailing macro-perspective overlooks spatiotemporal heterogeneity in diffusion processes.Therefore,taking monastery as the carrier,this study establishes a multi-level diffusion model to reconstruct the diffusion networks of Gelugpa monasteries,as well as a framework to explore the detailed features in the spatial diffusion processes of Gelugpa in Tibetan areas of China based on a geodatabase of Gelugpa monastery.The results show that the multi-level diffusion model has a considerable applicability in the reconstruction of the diffusion networks of Gelugpa monasteries.Gelugpa monasteries in the Three Tibetan Inhabited Areas present disparate spatial diffusion processes with diverse diffusion bases,speeds,stages,as well as diffusion regions and centers.A powerful single-center diffusion-centered Gandan Monastery was rapidly formed in U-Tsang.Kham experienced a slower and more varied spatial diffusion process with multiple diffusion systems far apart from each other.The spatial diffusion process of Amdo was the most complex,with the highest diffusion intensity.Amdo possessed the most influential diffusion centers,with different diffusion shapes and diffusion ranges crossing and overlapping with each other.Multiple natural and human factors may contribute to the formation of Gelugpa monasteries.This study contributes to the understanding of the geography of Gelugpa and provides reference to studies on religion diffusion.展开更多
HIV/AIDS is a public health problem especially in sub-Saharan Africa where majority of infections and deaths occur. Despite the large number of studies and efforts made in covering the data gap using mathematical mode...HIV/AIDS is a public health problem especially in sub-Saharan Africa where majority of infections and deaths occur. Despite the large number of studies and efforts made in covering the data gap using mathematical models, little is known on how model estimates are confounded by the transmission variabilities that exist in stages of HIV progression. This work investigates the impact of including stages of HIV transmission in HIV/AIDS models. A deterministic HIV/AIDS model is developed and extended to include stages of HIV progression of infected individuals. Theoretical investigation of the models and numerical analyses indicate that the two models produce different estimates, with the model without stages producing lower estimates than the staged model. These results call for a careful consideration in evaluating the efficiency of HIV/AIDS models that are used to estimate and project the burden of HIV/AIDS disease.展开更多
BACKGROUND: The indocyanine green (ICG) clearance test (clearance rate (K) and retention rate at 15 minutes (R(15))) is a sensitive indicator to evaluate liver function. The model for end-stage liver disease (MELD) sc...BACKGROUND: The indocyanine green (ICG) clearance test (clearance rate (K) and retention rate at 15 minutes (R(15))) is a sensitive indicator to evaluate liver function. The model for end-stage liver disease (MELD) score has emerged as a useful tool for estimating the mortality of patients awaiting liver transplantation and has recently been validated on patients with liver diseases of various etiologies and severity. In this study, we investigated the correlation between the ICG clearance test and MELD score of patients with liver cirrhosis. METHODS: From June 2007 to March 2008, 52 patients with liver cirrhosis admitted to our center were classified into Child-Pugh class A (8 patients), B (14) and C (30). The ICG clearance test (K value and R(15)) was performed by ICG pulse spectrophotometry (DDG-3300K), and the MELD scores of patients were calculated. RESULTS: As the Child-Pugh classification of liver function gradually deteriorated, the K value decreased, while R(15) and MELD score increased. There were significant statistical differences in K value, R(15) and MELD score in patients with different Child-Pugh classifications. Significant correlations were found between the parameters of the ICG clearance test (K value and R(15)) and MELD score. A negative correlation was observed between K value and MELD score (r=-0.892, P < 0.05), while a positive correlation was observed between R(15) and MELD score (r=0.804, P < 0.05). CONCLUSIONS: The ICG clearance test and MELD score are good parameters for evaluating liver function. Moreover, K value and R(15) have significant correlations with MELD score, especially the K value, which may be a convenient and appropriate indicator to evaluate liver function of patients with liver cirrhosis.展开更多
The final product quality is determined by cumulation, coupling and propagation of product quality variations from all stations in multi-stage manufacturing systems （MMSs）. Modeling and control of variation propagat...The final product quality is determined by cumulation, coupling and propagation of product quality variations from all stations in multi-stage manufacturing systems （MMSs）. Modeling and control of variation propagation is essential to improve product quality. However, the current stream of variations （SOV） theory can only solve the problem that a single SOV affects the product quality. Due to the existence of multiple variation streams, limited research has been done on the quality control in serial-parallel hybrid multi-stage manufacturing systems （SPH-MMSs）. A state space model and its modeling strategies are developed to describe the multiple variation streams stack-up in an SPH-MMS. The SOV theory is extended to SPH-MMS. The dimensions of system model are reduced to the production-reality level, and the effect and feasibility of the model is validated by a machining case.展开更多
A Holling type III predator-prey model with stage structure for prey is investi-gated. By analyzing the corresponding characteristic equations, the local stability of each of feasible equilibria of the system is discu...A Holling type III predator-prey model with stage structure for prey is investi-gated. By analyzing the corresponding characteristic equations, the local stability of each of feasible equilibria of the system is discussed. By using the uniformly persistence theory, the system is proven to be permanent if the coexistence equilibrium exists. By using Lyapunov functionals and LaSalle’s invariance principle, it is shown that the two boundary equilibria is globally asymptotically stable when the coexistence equilibrium is not feasible. By using compound matrix theory, the sucient conditions are obtained for the global stability of the coexistence equilibrium. At last, numerical simulations are carried out to illustrate the main results.展开更多
AIM: To compare the ability of model for end-stage liver disease(MELD)-Na and Maddrey discrimination function index(DFI) to predict mortality at 30 and 90 d in patients with alcoholic hepatitis(AH).METHODS: We prospec...AIM: To compare the ability of model for end-stage liver disease(MELD)-Na and Maddrey discrimination function index(DFI) to predict mortality at 30 and 90 d in patients with alcoholic hepatitis(AH).METHODS: We prospectively assessed 52 patients with AH. Demographic, clinical and laboratory parameters were obtained. MELD-Na and Maddrey DFI were calculated on admission. Short-term mortality was assessed at 30 and 90 d. Receiver operating characteristic curve analysis was performed. RESULTS: Thirty-day and 90-d mortality was 44% and 58%, respectively. In the univariate analysis, sodium levels was associated with mortality at 30 and 90 d(P = 0.001 and P = 0.03). Child stage, encephalopathy, ascites, or types of treatment were not associated with mortality. MELD-Na was the only predictive factor for mortality at 90 d. For 30-d mortality area under the curve(AUC) was 0.763(95%CI: 0.63-0.89) for Maddrey DFI and 0.784 for MELD-Na(95%CI: 0.65-0.91, P = 0.82). For 90-d mortality AUC was 0.685(95%CI: 0.54-0.83) for Maddrey DFI and 0.8710 for MELD-Na(95%CI: 0.76-0.97, P = 0.041). CONCLUSION: AH is associated with high shortterm mortality. Our results show that MELD-Na is a more valuable model than DFI to predict short-term mortality.展开更多
BACKGROUND: Controversy exists over whether living donor liver transplantation (LDLT) should be offered to patients with high Model for End-stage Liver Disease (MELD) scores. This study tried to determine whether a hi...BACKGROUND: Controversy exists over whether living donor liver transplantation (LDLT) should be offered to patients with high Model for End-stage Liver Disease (MELD) scores. This study tried to determine whether a high MELD score would result in inferior outcomes of right-lobe LDLT. METHODS: Among 411 consecutive patients who received right-lobe LDLT at our center, 143 were included in this study. The patients were divided into two groups according to their MELD scores: a high-score group (MELD score ≥25; n=75) and a low-score group (MELD score 【25; n=68). Their demographic data and perioperative conditions were compared. Univariable and multivariable analyses were performed to identify risk factors affecting patient survival. RESULTS: In the high-score group, more patients required preoperative intensive care unit admission (49.3% vs 2.9%; P【0.001), mechanical ventilation (21.3% vs 0%; P【0.001), or hemodialysis (13.3% vs 0%; P=0.005); the waiting time before LDLT was shorter (4 vs 66 days; P【0.001); more blood was transfused during operation (7 vs 2 units; P【0.001); patients stayed longer in the intensive care unit (6 vs 3 days; P【0.001) and hospital (21 vs 15 days; P=0.015) after transplantation;more patients developed early postoperative complications (69.3% vs 50.0%; P=0.018); and values of postoperative peak blood parameters were higher. However, the two groups had comparable hospital mortality. Graft survival and patient overall survival at one year (94.7% vs 95.6%; 95.9% vs 96.9%), three years (91.9% vs 92.6%; 93.2% vs 95.3%), and five years (90.2% vs 90.2%; 93.2% vs 95.3%) were also similar between the groups. CONCLUSIONS: Although the high-score group had signifi-cantly more early postoperative complications, the two groups had comparable hospital mortality and similar satisfactory rates of graft survival and patient overall survival. Therefore, a high MELD score should not be a contraindication to right-lobe LDLT if donor risk and recipient benefit are taken into full account.展开更多
God depeits occurring in metamorPhaed microclastic rocks are distributed exten-sively at home and abroad. Some deposits of this type are of superlarge tonnage. The formation of gold deposits in metamorphosed microclas...God depeits occurring in metamorPhaed microclastic rocks are distributed exten-sively at home and abroad. Some deposits of this type are of superlarge tonnage. The formation of gold deposits in metamorphosed microclastic rocks involves three stages: the sedimentary stage, the regionally metamorpphic stage, and the ore-forming stage. At the first stage, microclastic sedimentary source rocks were developed in a relatively semi-enclosed reducing sea basin and were enriched in carbon, sulfur and gold. At the second stage, the gold adsorbed on organic matter and clay minerals was released and poorly concentrated during the destruction of organic matter and the depletion of clay minerals by regional metamorphism with increase temperature and pressre. At the third stage, a tectono-hydrothermal event took place. As a result, gold was leached from metamorphosed microclastic rocks, transported to ore depositional locus and/or mixed with gold of other sources in the course of migration, and finally precipitated as ores. Gold deposits of this type were eventually formed at the third stage, and they also can be classified as the orognic belt type and the activation zone type. The gold deposits occurring in metamorphosed microclastic rocks are the products of reworking processes and the influence of magmatism should be taken into consideration in some cases.展开更多
BACKGROUND:Decreased cardiac contractility has been observed in cirrhosis,suggesting a latent cardiomyopathy in these patients.This study was designed to evaluate left ventricular structure and function in patients wi...BACKGROUND:Decreased cardiac contractility has been observed in cirrhosis,suggesting a latent cardiomyopathy in these patients.This study was designed to evaluate left ventricular structure and function in patients with end-stage liver disease by the model for end-stage liver disease(MELD) scoring system. METHODS:We recruited 82 patients(72 male,10 female; mean age 50.3±8.9 years)with end-stage liver disease who underwent orthotopic liver transplantation between January 2002 and May 2008.Seventy-eight patients had cirrhosis and 4 had primary liver cancer.Patients were categorized into three groups on the basis of MELD score:≤9(27 patients, 33%);10-19(40,49%);and≥20(15,18%).The relationship between MELD score and cardiac structure and function was determined.Preoperative assessments of blood biochemistry, blood coagulation,serum virology,echocardiography and electrocardiography were performed. RESULTS:MELD score was positively correlated with enlarged left atrial diameter,increased interventricular septum thickness(IVST),increased aortic flow,corrected QT interval (QTc)extension and cardiac output(P=0.033,0.002,0.000, 0.000 and 0.009,respectively).International normalized ratio also had a correlation with the above parameters and enlarged left ventricular end-diastolic diameter(P=0.043,0.010,0.000, 0.001,0.016 and 0.008,respectively).Serum creatinine was positively correlated with IVST(r=0.257,P=0.020),but negatively correlated with early maximal ventricular filling velocity/late diastolic or atrial velocity ratio(r=-0.300, P=0.006).A difference of QTc>440 ms among the three groups was statistically significant(χ2=9.791,P=0.007).CONCLUSIONS:Abnormalities in cardiac structure and function are common in patients with end-stage liver disease. MELD score is a practically useful approach for the assessment of cardiac function in such patients.展开更多
AIM To investigate whether the short-term prognosis of hepatitis B virus(HBV)-related acute-on-chronic liver failure(ACLF) could be improved by using a modified model for end-stage liver disease(MELD) including serum ...AIM To investigate whether the short-term prognosis of hepatitis B virus(HBV)-related acute-on-chronic liver failure(ACLF) could be improved by using a modified model for end-stage liver disease(MELD) including serum lactate.METHODS This clinical study was conducted at the First Affiliated Hospital, Fujian Medicine University, China. From 2009 to 2015, 236 patients diagnosed with HBV-related ACLF at our center were recruited for this 3-month followup study. Demographic data and serum lactate levels were collected from the patients. The MELD scores with or without serum lactate levels from survival and nonsurvival groups were recorded and compared.RESULTS Two hundred and thirty-six patients with HBV-ACLF were divided into two groups: survival group(S) andnon-survival group(NS). Compared with the NS group, the patients in survival the S group had a significantly lower level of serum lactate(3.11 ± 1.98 vs 4.67 ± 2.43, t = 5.43, P < 0.001) and MELD score(23.33 ± 5.42 vs 30.37 ± 6.58, t = 9.01, P = 0.023). Furthermore, serum lactate level was positively correlated with MELD score(r = 0.315, P < 0.001). Therefore, a modified MELD including serum lactate was developed by logistic regression analysis(0.314 × lactate + 0.172 × MELD-5.923). In predicting 3-month mortality using the MELD-LAC model, the patients from the S group had significantly lower baseline scores(-0.930 ± 1.34) when compared with those from the NS group(0.771 ± 1.32, t = 9.735, P < 0.001). The area under the receiver operating characteristic curve(AUROC) was 0.859 calculated by using the MELD-LAC model, which was significantly higher than that calculated by using the lactate level(0.790) or MELD alone(0.818). When the cutoff value was set at-0.4741, the sensitivity, specificity, positive predictive value and negative predictive value for predicting short-term mortality were 91.5%, 80.10%, 94.34% and 74.62%, respectively. When the MELD-LAC scores at baseline level were set at-0.5561 and 0.6879, the corresponding mortality rates within three months were 75% and 90%, respectively.CONCLUSION The short-term prognosis of HBV-related ACLF was improved by using a modified MELD including serum lactate from the present 6-year clinical study.展开更多
This paper introduces a practical solving scheme of gradetransition trajectory optimization(GTTO) problems under typical certificate-checking–updating framework. Due to complicated kinetics of polymerization,differen...This paper introduces a practical solving scheme of gradetransition trajectory optimization(GTTO) problems under typical certificate-checking–updating framework. Due to complicated kinetics of polymerization,differential/algebraic equations(DAEs) always cause great computational burden and system non-linearity usually makes GTTO non-convex bearing multiple optima. Therefore, coupled with the three-stage decomposition model, a three-section algorithm of dynamic programming(TSDP) is proposed based on the general iteration mechanism of iterative programming(IDP) and incorporated with adaptivegrid allocation scheme and heuristic modifications. The algorithm iteratively performs dynamic programming with heuristic modifications under constant calculation loads and adaptively allocates the valued computational resources to the regions that can further improve the optimality under the guidance of local error estimates. TSDP is finally compared with IDP and interior point method(IP) to verify its efficiency of computation.展开更多
In this paper, a stochastic predator-prey model with stage structure for predatorand ratio-dependent functional response is concerned. Sufficient conditions for the globalasymptotic stability of positive equilibrium a...In this paper, a stochastic predator-prey model with stage structure for predatorand ratio-dependent functional response is concerned. Sufficient conditions for the globalasymptotic stability of positive equilibrium are established. Some numerical simulations arecarried out to illustrate the theoretical results.展开更多
In this paper we proposed an AMH Supply Chain model to obtain optimal solutions for Two-, Three- and Four-Stage for deterministic models. Besides deriving its algebraic solutions, a simple searching method is successf...In this paper we proposed an AMH Supply Chain model to obtain optimal solutions for Two-, Three- and Four-Stage for deterministic models. Besides deriving its algebraic solutions, a simple searching method is successfully applied in obtaining optimal total costs and its integer multipliers. Our model has shown promising results in comparison to Equal Cycle Time and other existing ones. The tests focused on obtaining optimal total annual costs and other related details of Two-, Three- and Four-Stage for deterministic models. The results are run under Visual Basic Programming platform using Intel? CoreTM2 Duo T6500 Processor.展开更多
The temperature field in unsteady phase greatly affects the quality of friction plug welding(FPW).An analytical model is put forward to correlate the process parameters and the temperature field in unsteady phase of F...The temperature field in unsteady phase greatly affects the quality of friction plug welding(FPW).An analytical model is put forward to correlate the process parameters and the temperature field in unsteady phase of FPW.Applying the von Mises criterion for plastic deformation and linearizing the heat flux,the model is achieved by Laplace transformation.The predicated peak temperature and peak time agree with the experiment data,with errors of about 4%and 8%,of AA7075-T6 FPW.展开更多
This paper presents the compliance modeling of a compliant stage with symmetric configuration. Empirical compliance equations for the circular flexure hinge are first introduced. Using the matrix method, the output co...This paper presents the compliance modeling of a compliant stage with symmetric configuration. Empirical compliance equations for the circular flexure hinge are first introduced. Using the matrix method, the output compliance of a compliant stage with symmetric configuration is then obtained. Finally, the compliances derived from the proposed theoretical model and finite element analysis (FEA) are compared. It indicates that the results calculated by the theoretical model are in good agreement with those derived from FEA, which demonstrates the accuracy of the theoretical model.展开更多
文摘Abstract: The great majority of the Palaeozoic orogenic belts of Central Asia are of the intercontinental type, whose evolution always follows a five-stage model, i.e. the basal continental crust-extensional transitional crust-oceanic crust-convergent transitional crust-new continental crust model. The stage for the extensional transitional crust is a pretty long, independent and inevitable phase. The dismembering mechanism of the basal continental crust becoming an extensional continental crust is delineated by the simple shear model put forward by Wernike (1981). The continental margins on the sides of a gently dipping detachment zone and moving along it are asymmetric: one side is of the nonmagmatic type and the other of the magmatic type with a typical bimodal volcanic formation. In the latter case, however, they were often confused with island arcs. This paper discusses the five-stage process of the crustal evolution of some typical orogenic belts in Xinjiang.
文摘For the cyclic process of mass transfer in tray columns there are considered the hydrodynamic models of liquid flow during steam supply and during overflow of liquid from tray to tray. During steam supply, the hydrodynamic model is determined as perfect displacement model, and during liquid overflow, it is described as cell model. There were received the characteristics of liquid flow as follows： average residence time of liquid, degree of dispersion around the mean on the tray, number of perfect mixing cells depending on multiplication factor of exchange of liquid delay. In Y-X coordinates there is depicted a work line and theoretical stage of perfect displacement model. There were considered the conditions of mutual transfer of theoretical stage and theoretical stage with perfect displacement. The advantages of the mass transfer cyclic process to the stationary one arc stated.
基金supported by the Humanities and Social Sciences Foundation of the Ministry of Education of China(Grant No.18YJAZH140).
文摘Gelugpa is the most influential extant religious sect of Tibetan Buddhism,which is the spiritual prop for Tibetans,with thousands of monasteries and followers in Tibetan areas of China.Studies on the spatial diffusion processes of Gelugpa can not only reveal its historical geographical development but also lay the foundation for anticipating its future development trend.However,existing studies on Gelugpa lack geographical perspective,making it difficult to explore the spatial characteristics.Furthermore,the prevailing macro-perspective overlooks spatiotemporal heterogeneity in diffusion processes.Therefore,taking monastery as the carrier,this study establishes a multi-level diffusion model to reconstruct the diffusion networks of Gelugpa monasteries,as well as a framework to explore the detailed features in the spatial diffusion processes of Gelugpa in Tibetan areas of China based on a geodatabase of Gelugpa monastery.The results show that the multi-level diffusion model has a considerable applicability in the reconstruction of the diffusion networks of Gelugpa monasteries.Gelugpa monasteries in the Three Tibetan Inhabited Areas present disparate spatial diffusion processes with diverse diffusion bases,speeds,stages,as well as diffusion regions and centers.A powerful single-center diffusion-centered Gandan Monastery was rapidly formed in U-Tsang.Kham experienced a slower and more varied spatial diffusion process with multiple diffusion systems far apart from each other.The spatial diffusion process of Amdo was the most complex,with the highest diffusion intensity.Amdo possessed the most influential diffusion centers,with different diffusion shapes and diffusion ranges crossing and overlapping with each other.Multiple natural and human factors may contribute to the formation of Gelugpa monasteries.This study contributes to the understanding of the geography of Gelugpa and provides reference to studies on religion diffusion.
文摘HIV/AIDS is a public health problem especially in sub-Saharan Africa where majority of infections and deaths occur. Despite the large number of studies and efforts made in covering the data gap using mathematical models, little is known on how model estimates are confounded by the transmission variabilities that exist in stages of HIV progression. This work investigates the impact of including stages of HIV transmission in HIV/AIDS models. A deterministic HIV/AIDS model is developed and extended to include stages of HIV progression of infected individuals. Theoretical investigation of the models and numerical analyses indicate that the two models produce different estimates, with the model without stages producing lower estimates than the staged model. These results call for a careful consideration in evaluating the efficiency of HIV/AIDS models that are used to estimate and project the burden of HIV/AIDS disease.
文摘BACKGROUND: The indocyanine green (ICG) clearance test (clearance rate (K) and retention rate at 15 minutes (R(15))) is a sensitive indicator to evaluate liver function. The model for end-stage liver disease (MELD) score has emerged as a useful tool for estimating the mortality of patients awaiting liver transplantation and has recently been validated on patients with liver diseases of various etiologies and severity. In this study, we investigated the correlation between the ICG clearance test and MELD score of patients with liver cirrhosis. METHODS: From June 2007 to March 2008, 52 patients with liver cirrhosis admitted to our center were classified into Child-Pugh class A (8 patients), B (14) and C (30). The ICG clearance test (K value and R(15)) was performed by ICG pulse spectrophotometry (DDG-3300K), and the MELD scores of patients were calculated. RESULTS: As the Child-Pugh classification of liver function gradually deteriorated, the K value decreased, while R(15) and MELD score increased. There were significant statistical differences in K value, R(15) and MELD score in patients with different Child-Pugh classifications. Significant correlations were found between the parameters of the ICG clearance test (K value and R(15)) and MELD score. A negative correlation was observed between K value and MELD score (r=-0.892, P < 0.05), while a positive correlation was observed between R(15) and MELD score (r=0.804, P < 0.05). CONCLUSIONS: The ICG clearance test and MELD score are good parameters for evaluating liver function. Moreover, K value and R(15) have significant correlations with MELD score, especially the K value, which may be a convenient and appropriate indicator to evaluate liver function of patients with liver cirrhosis.
基金This project is supported by National Natural Science Foundation of China(No.50675137).
文摘The final product quality is determined by cumulation, coupling and propagation of product quality variations from all stations in multi-stage manufacturing systems （MMSs）. Modeling and control of variation propagation is essential to improve product quality. However, the current stream of variations （SOV） theory can only solve the problem that a single SOV affects the product quality. Due to the existence of multiple variation streams, limited research has been done on the quality control in serial-parallel hybrid multi-stage manufacturing systems （SPH-MMSs）. A state space model and its modeling strategies are developed to describe the multiple variation streams stack-up in an SPH-MMS. The SOV theory is extended to SPH-MMS. The dimensions of system model are reduced to the production-reality level, and the effect and feasibility of the model is validated by a machining case.
基金Supported by the NSFC(11371368)Supported by the Basic Courses Department of OEC Foundation(Jcky1302)
文摘A Holling type III predator-prey model with stage structure for prey is investi-gated. By analyzing the corresponding characteristic equations, the local stability of each of feasible equilibria of the system is discussed. By using the uniformly persistence theory, the system is proven to be permanent if the coexistence equilibrium exists. By using Lyapunov functionals and LaSalle’s invariance principle, it is shown that the two boundary equilibria is globally asymptotically stable when the coexistence equilibrium is not feasible. By using compound matrix theory, the sucient conditions are obtained for the global stability of the coexistence equilibrium. At last, numerical simulations are carried out to illustrate the main results.
文摘AIM: To compare the ability of model for end-stage liver disease(MELD)-Na and Maddrey discrimination function index(DFI) to predict mortality at 30 and 90 d in patients with alcoholic hepatitis(AH).METHODS: We prospectively assessed 52 patients with AH. Demographic, clinical and laboratory parameters were obtained. MELD-Na and Maddrey DFI were calculated on admission. Short-term mortality was assessed at 30 and 90 d. Receiver operating characteristic curve analysis was performed. RESULTS: Thirty-day and 90-d mortality was 44% and 58%, respectively. In the univariate analysis, sodium levels was associated with mortality at 30 and 90 d(P = 0.001 and P = 0.03). Child stage, encephalopathy, ascites, or types of treatment were not associated with mortality. MELD-Na was the only predictive factor for mortality at 90 d. For 30-d mortality area under the curve(AUC) was 0.763(95%CI: 0.63-0.89) for Maddrey DFI and 0.784 for MELD-Na(95%CI: 0.65-0.91, P = 0.82). For 90-d mortality AUC was 0.685(95%CI: 0.54-0.83) for Maddrey DFI and 0.8710 for MELD-Na(95%CI: 0.76-0.97, P = 0.041). CONCLUSION: AH is associated with high shortterm mortality. Our results show that MELD-Na is a more valuable model than DFI to predict short-term mortality.
文摘BACKGROUND: Controversy exists over whether living donor liver transplantation (LDLT) should be offered to patients with high Model for End-stage Liver Disease (MELD) scores. This study tried to determine whether a high MELD score would result in inferior outcomes of right-lobe LDLT. METHODS: Among 411 consecutive patients who received right-lobe LDLT at our center, 143 were included in this study. The patients were divided into two groups according to their MELD scores: a high-score group (MELD score ≥25; n=75) and a low-score group (MELD score 【25; n=68). Their demographic data and perioperative conditions were compared. Univariable and multivariable analyses were performed to identify risk factors affecting patient survival. RESULTS: In the high-score group, more patients required preoperative intensive care unit admission (49.3% vs 2.9%; P【0.001), mechanical ventilation (21.3% vs 0%; P【0.001), or hemodialysis (13.3% vs 0%; P=0.005); the waiting time before LDLT was shorter (4 vs 66 days; P【0.001); more blood was transfused during operation (7 vs 2 units; P【0.001); patients stayed longer in the intensive care unit (6 vs 3 days; P【0.001) and hospital (21 vs 15 days; P=0.015) after transplantation;more patients developed early postoperative complications (69.3% vs 50.0%; P=0.018); and values of postoperative peak blood parameters were higher. However, the two groups had comparable hospital mortality. Graft survival and patient overall survival at one year (94.7% vs 95.6%; 95.9% vs 96.9%), three years (91.9% vs 92.6%; 93.2% vs 95.3%), and five years (90.2% vs 90.2%; 93.2% vs 95.3%) were also similar between the groups. CONCLUSIONS: Although the high-score group had signifi-cantly more early postoperative complications, the two groups had comparable hospital mortality and similar satisfactory rates of graft survival and patient overall survival. Therefore, a high MELD score should not be a contraindication to right-lobe LDLT if donor risk and recipient benefit are taken into full account.
文摘God depeits occurring in metamorPhaed microclastic rocks are distributed exten-sively at home and abroad. Some deposits of this type are of superlarge tonnage. The formation of gold deposits in metamorphosed microclastic rocks involves three stages: the sedimentary stage, the regionally metamorpphic stage, and the ore-forming stage. At the first stage, microclastic sedimentary source rocks were developed in a relatively semi-enclosed reducing sea basin and were enriched in carbon, sulfur and gold. At the second stage, the gold adsorbed on organic matter and clay minerals was released and poorly concentrated during the destruction of organic matter and the depletion of clay minerals by regional metamorphism with increase temperature and pressre. At the third stage, a tectono-hydrothermal event took place. As a result, gold was leached from metamorphosed microclastic rocks, transported to ore depositional locus and/or mixed with gold of other sources in the course of migration, and finally precipitated as ores. Gold deposits of this type were eventually formed at the third stage, and they also can be classified as the orognic belt type and the activation zone type. The gold deposits occurring in metamorphosed microclastic rocks are the products of reworking processes and the influence of magmatism should be taken into consideration in some cases.
基金supported by a grant from the Science and Technology Bureau of Liaoning Province,China(2007225011-1)
文摘BACKGROUND:Decreased cardiac contractility has been observed in cirrhosis,suggesting a latent cardiomyopathy in these patients.This study was designed to evaluate left ventricular structure and function in patients with end-stage liver disease by the model for end-stage liver disease(MELD) scoring system. METHODS:We recruited 82 patients(72 male,10 female; mean age 50.3±8.9 years)with end-stage liver disease who underwent orthotopic liver transplantation between January 2002 and May 2008.Seventy-eight patients had cirrhosis and 4 had primary liver cancer.Patients were categorized into three groups on the basis of MELD score:≤9(27 patients, 33%);10-19(40,49%);and≥20(15,18%).The relationship between MELD score and cardiac structure and function was determined.Preoperative assessments of blood biochemistry, blood coagulation,serum virology,echocardiography and electrocardiography were performed. RESULTS:MELD score was positively correlated with enlarged left atrial diameter,increased interventricular septum thickness(IVST),increased aortic flow,corrected QT interval (QTc)extension and cardiac output(P=0.033,0.002,0.000, 0.000 and 0.009,respectively).International normalized ratio also had a correlation with the above parameters and enlarged left ventricular end-diastolic diameter(P=0.043,0.010,0.000, 0.001,0.016 and 0.008,respectively).Serum creatinine was positively correlated with IVST(r=0.257,P=0.020),but negatively correlated with early maximal ventricular filling velocity/late diastolic or atrial velocity ratio(r=-0.300, P=0.006).A difference of QTc>440 ms among the three groups was statistically significant(χ2=9.791,P=0.007).CONCLUSIONS:Abnormalities in cardiac structure and function are common in patients with end-stage liver disease. MELD score is a practically useful approach for the assessment of cardiac function in such patients.
文摘AIM To investigate whether the short-term prognosis of hepatitis B virus(HBV)-related acute-on-chronic liver failure(ACLF) could be improved by using a modified model for end-stage liver disease(MELD) including serum lactate.METHODS This clinical study was conducted at the First Affiliated Hospital, Fujian Medicine University, China. From 2009 to 2015, 236 patients diagnosed with HBV-related ACLF at our center were recruited for this 3-month followup study. Demographic data and serum lactate levels were collected from the patients. The MELD scores with or without serum lactate levels from survival and nonsurvival groups were recorded and compared.RESULTS Two hundred and thirty-six patients with HBV-ACLF were divided into two groups: survival group(S) andnon-survival group(NS). Compared with the NS group, the patients in survival the S group had a significantly lower level of serum lactate(3.11 ± 1.98 vs 4.67 ± 2.43, t = 5.43, P < 0.001) and MELD score(23.33 ± 5.42 vs 30.37 ± 6.58, t = 9.01, P = 0.023). Furthermore, serum lactate level was positively correlated with MELD score(r = 0.315, P < 0.001). Therefore, a modified MELD including serum lactate was developed by logistic regression analysis(0.314 × lactate + 0.172 × MELD-5.923). In predicting 3-month mortality using the MELD-LAC model, the patients from the S group had significantly lower baseline scores(-0.930 ± 1.34) when compared with those from the NS group(0.771 ± 1.32, t = 9.735, P < 0.001). The area under the receiver operating characteristic curve(AUROC) was 0.859 calculated by using the MELD-LAC model, which was significantly higher than that calculated by using the lactate level(0.790) or MELD alone(0.818). When the cutoff value was set at-0.4741, the sensitivity, specificity, positive predictive value and negative predictive value for predicting short-term mortality were 91.5%, 80.10%, 94.34% and 74.62%, respectively. When the MELD-LAC scores at baseline level were set at-0.5561 and 0.6879, the corresponding mortality rates within three months were 75% and 90%, respectively.CONCLUSION The short-term prognosis of HBV-related ACLF was improved by using a modified MELD including serum lactate from the present 6-year clinical study.
基金Supported by the National Basic Research Program of China(2012CB720500)the National High Technology Research and Development Program of China(2013AA040702)
文摘This paper introduces a practical solving scheme of gradetransition trajectory optimization(GTTO) problems under typical certificate-checking–updating framework. Due to complicated kinetics of polymerization,differential/algebraic equations(DAEs) always cause great computational burden and system non-linearity usually makes GTTO non-convex bearing multiple optima. Therefore, coupled with the three-stage decomposition model, a three-section algorithm of dynamic programming(TSDP) is proposed based on the general iteration mechanism of iterative programming(IDP) and incorporated with adaptivegrid allocation scheme and heuristic modifications. The algorithm iteratively performs dynamic programming with heuristic modifications under constant calculation loads and adaptively allocates the valued computational resources to the regions that can further improve the optimality under the guidance of local error estimates. TSDP is finally compared with IDP and interior point method(IP) to verify its efficiency of computation.
基金Supported by the National Natural Science Foundation of China(Nos.11371368)The Natural Science Foundation of HeBei(No.A2014506015)
文摘In this paper, a stochastic predator-prey model with stage structure for predatorand ratio-dependent functional response is concerned. Sufficient conditions for the globalasymptotic stability of positive equilibrium are established. Some numerical simulations arecarried out to illustrate the theoretical results.
文摘In this paper we proposed an AMH Supply Chain model to obtain optimal solutions for Two-, Three- and Four-Stage for deterministic models. Besides deriving its algebraic solutions, a simple searching method is successfully applied in obtaining optimal total costs and its integer multipliers. Our model has shown promising results in comparison to Equal Cycle Time and other existing ones. The tests focused on obtaining optimal total annual costs and other related details of Two-, Three- and Four-Stage for deterministic models. The results are run under Visual Basic Programming platform using Intel? CoreTM2 Duo T6500 Processor.
文摘The temperature field in unsteady phase greatly affects the quality of friction plug welding(FPW).An analytical model is put forward to correlate the process parameters and the temperature field in unsteady phase of FPW.Applying the von Mises criterion for plastic deformation and linearizing the heat flux,the model is achieved by Laplace transformation.The predicated peak temperature and peak time agree with the experiment data,with errors of about 4%and 8%,of AA7075-T6 FPW.
文摘This paper presents the compliance modeling of a compliant stage with symmetric configuration. Empirical compliance equations for the circular flexure hinge are first introduced. Using the matrix method, the output compliance of a compliant stage with symmetric configuration is then obtained. Finally, the compliances derived from the proposed theoretical model and finite element analysis (FEA) are compared. It indicates that the results calculated by the theoretical model are in good agreement with those derived from FEA, which demonstrates the accuracy of the theoretical model.
