The number of patients reinitiating dialysis after a failed transplant increases over time and has more than doubled between the year 1988 and 2010 （an increase from 2463 to 5588）. More importantly, patients returni...The number of patients reinitiating dialysis after a failed transplant increases over time and has more than doubled between the year 1988 and 2010 （an increase from 2463 to 5588）. More importantly, patients returning to dialysis have been shown to have a greater thanthree-fold increase in the annual adjusted mortality rates compared with those with a functioning graft. Continuation of immunosuppression to preserve residual graft function has been implicated to be a contributing factor, seemingly due to immunosuppression-ass-ociated cardiovascular and infectious complications and malignancy risk, among others. Nonetheless, maintenance low-dose immunosuppression has been suggested to confer survival beneft in patients returning to peritoneal dialysis. Whether early vs late reinitiation of dialysis or whether transplantectomy has an impact on patient survival remains poorly defined. Consensus guidelines for the management of a failed allograft are lacking. In this article, we present a literature overview on the ideal timing of dialysis reinitiation after graft loss, the management of immunosuppression after graft failure, and the risks and benefits of transplantectomy. The authors’ perspectives on the management of this special patient population are also discussed.展开更多
The unprecedented wheat yield increases during the Green Revolution were achieved through the introduc-tion of the Reduced height(Rht)-B1b and Rht-D1b semi-dwarfing alleles.These Rht-1 alleles encode growth-repressing...The unprecedented wheat yield increases during the Green Revolution were achieved through the introduc-tion of the Reduced height(Rht)-B1b and Rht-D1b semi-dwarfing alleles.These Rht-1 alleles encode growth-repressing DELLA genes containing a stop codon within their open reading frame that confers gibberellin(GA)-insensitive semi-dwarfism.In this study,we successfully took the hurdle of detecting wild-type RHT-1 proteins in different wheat organs and confirmed their degradation in response to GAs.We further demonstrated that Rht-B1b and Rht-D1b produce N-terminal truncated proteins through trans-lational reinitiation.Expression of these N-terminal truncated proteins in transgenic lines and in Rht-D1c,an allele containing multiple Rht-D1b copies,demonstrated their ability to cause strong dwarfism,resulting from their insensitivity to GA-mediated degradation.N-terminal truncated proteins were detected in spikes and nodes,but not in the aleurone layers.Since Rht-B 1b and Rht-D1b alleles cause dwarfism but have wild-type dormancy,this finding suggests that tissue-specific differences in translational reinitiation may explain why the Rht-1 alleles reduce plant height without affecting dormancy.Taken together,our findings not only reveal the molecular mechanism underlying the Green Revolution but also demonstrate that trans-lational reinitiation in the main open reading frame occurs in plants.展开更多
Hydraulic fracturing is a mainstream technology for unconventional oil and gas reservoirs development all over the world.How to use this technology to achieve high-level oil and gas resource extraction and how to form...Hydraulic fracturing is a mainstream technology for unconventional oil and gas reservoirs development all over the world.How to use this technology to achieve high-level oil and gas resource extraction and how to form complex fracture networks as hydrocarbon transportation channels in tight reservoirs,which depends to a large extent on the interaction between hydraulic and pre-existing cracks.For hydraulic fracturing of fractured reservoirs,the impact of natural fractures,perforation direction,stress disturbances,faults and other influencing factors will produce a mixed I&II mode hydraulic fracture.To forecast whether hydraulic fractures cross pre-existing fractures,according to elastic mechanics and fracture mechanics,a stress state of cracks under the combination of tensile(I)and shear(II)is presented.A simple mixed-mode I&II hydraulic fracture's crossing judgment criterion is established,and the propagation of hydraulic fractures after encountering natural fractures is analyzed.The results show that for a given approaching angle there exists a certain range of stress ratio when crossing occurs.Under high approaching angle and large stress ratio,it is likely that hydraulic cracks will go directly through pre-existing cracks.The reinitiated angle is always controlled within the range of approximately 30among the main direction of penetration.展开更多
A volume-amending method is developed both to keep the level set function as an algebraic distance function and to preserve the bubble mass in a level set approach for incompressible two-phase flows with the significa...A volume-amending method is developed both to keep the level set function as an algebraic distance function and to preserve the bubble mass in a level set approach for incompressible two-phase flows with the significantly deformed free interface. After the traditional reinitialization procedure, a vol-ume-amending method is added for correcting the position of the interface according to mass loss/gain error until the mass error falls in the allowable range designated in advance. The level set approach with this volume-amending method incorporated has been validated by three test cases: the motion of a single axisymmetrical bubble or drop in liquid, the motion of a two-dimensional water drop falling through the air into a water pool, and the interactional motion of two buoyancy-driven three- dimensional deformable bubbles. The computational results with this volume-amending method in-corporated are in good agreement with the reported experimental data and the mass is well preserved in all cases.展开更多
A new finite element level set method is developed to simulate the interface motion.The normal velocity of the moving interface can depend on both the local geometry,such as the curvature,and the external force such a...A new finite element level set method is developed to simulate the interface motion.The normal velocity of the moving interface can depend on both the local geometry,such as the curvature,and the external force such as that due to the flux from both sides of the interface of a material whose concentration is governed by a diffusion equation.The key idea of the method is to use an interface-fitted finite element mesh.Such an approximation of the interface allows an accurate calculation of the solution to the diffusion equation.The interface-fitted mesh is constructed from a base mesh,a uniform finite element mesh,at each time step to explicitly locate the interface and separate regions defined by the interface.Several new level set techniques are developed in the framework of finite element methods.These include a simple finite element method for approximating the curvature,a new method for the extension of normal velocity,and a finite element least-squares method for the reinitialization of level set functions.Application of the method to the classical solidification problem captures the dendrites.The method is also applied to the molecular solvation to determine optimal solute-solvent interfaces of solvation systems.展开更多
文摘The number of patients reinitiating dialysis after a failed transplant increases over time and has more than doubled between the year 1988 and 2010 （an increase from 2463 to 5588）. More importantly, patients returning to dialysis have been shown to have a greater thanthree-fold increase in the annual adjusted mortality rates compared with those with a functioning graft. Continuation of immunosuppression to preserve residual graft function has been implicated to be a contributing factor, seemingly due to immunosuppression-ass-ociated cardiovascular and infectious complications and malignancy risk, among others. Nonetheless, maintenance low-dose immunosuppression has been suggested to confer survival beneft in patients returning to peritoneal dialysis. Whether early vs late reinitiation of dialysis or whether transplantectomy has an impact on patient survival remains poorly defined. Consensus guidelines for the management of a failed allograft are lacking. In this article, we present a literature overview on the ideal timing of dialysis reinitiation after graft loss, the management of immunosuppression after graft failure, and the risks and benefits of transplantectomy. The authors’ perspectives on the management of this special patient population are also discussed.
基金D.V.D.S.acknowledges Ghent University for financial support.S.T.was supported by the Biotechnology and Biological Sciences Research Council Designing Future Wheat Cross Institute Strategic Programme(grant BB/P016855/1).
文摘The unprecedented wheat yield increases during the Green Revolution were achieved through the introduc-tion of the Reduced height(Rht)-B1b and Rht-D1b semi-dwarfing alleles.These Rht-1 alleles encode growth-repressing DELLA genes containing a stop codon within their open reading frame that confers gibberellin(GA)-insensitive semi-dwarfism.In this study,we successfully took the hurdle of detecting wild-type RHT-1 proteins in different wheat organs and confirmed their degradation in response to GAs.We further demonstrated that Rht-B1b and Rht-D1b produce N-terminal truncated proteins through trans-lational reinitiation.Expression of these N-terminal truncated proteins in transgenic lines and in Rht-D1c,an allele containing multiple Rht-D1b copies,demonstrated their ability to cause strong dwarfism,resulting from their insensitivity to GA-mediated degradation.N-terminal truncated proteins were detected in spikes and nodes,but not in the aleurone layers.Since Rht-B 1b and Rht-D1b alleles cause dwarfism but have wild-type dormancy,this finding suggests that tissue-specific differences in translational reinitiation may explain why the Rht-1 alleles reduce plant height without affecting dormancy.Taken together,our findings not only reveal the molecular mechanism underlying the Green Revolution but also demonstrate that trans-lational reinitiation in the main open reading frame occurs in plants.
基金supported by National Natural Science Foundation of China (52074248)Fundamental Research Funds for the Central Universities (2652019105,2652022207).
文摘Hydraulic fracturing is a mainstream technology for unconventional oil and gas reservoirs development all over the world.How to use this technology to achieve high-level oil and gas resource extraction and how to form complex fracture networks as hydrocarbon transportation channels in tight reservoirs,which depends to a large extent on the interaction between hydraulic and pre-existing cracks.For hydraulic fracturing of fractured reservoirs,the impact of natural fractures,perforation direction,stress disturbances,faults and other influencing factors will produce a mixed I&II mode hydraulic fracture.To forecast whether hydraulic fractures cross pre-existing fractures,according to elastic mechanics and fracture mechanics,a stress state of cracks under the combination of tensile(I)and shear(II)is presented.A simple mixed-mode I&II hydraulic fracture's crossing judgment criterion is established,and the propagation of hydraulic fractures after encountering natural fractures is analyzed.The results show that for a given approaching angle there exists a certain range of stress ratio when crossing occurs.Under high approaching angle and large stress ratio,it is likely that hydraulic cracks will go directly through pre-existing cracks.The reinitiated angle is always controlled within the range of approximately 30among the main direction of penetration.
基金the National Natural Science Foundation of China (Grant Nos. 20490206, 50404009, 20576133 & 20676134)PetroChina,and the National Basic Research Priorities Program (Grant Nos. 2004CB217604, 2007CB613507)
文摘A volume-amending method is developed both to keep the level set function as an algebraic distance function and to preserve the bubble mass in a level set approach for incompressible two-phase flows with the significantly deformed free interface. After the traditional reinitialization procedure, a vol-ume-amending method is added for correcting the position of the interface according to mass loss/gain error until the mass error falls in the allowable range designated in advance. The level set approach with this volume-amending method incorporated has been validated by three test cases: the motion of a single axisymmetrical bubble or drop in liquid, the motion of a two-dimensional water drop falling through the air into a water pool, and the interactional motion of two buoyancy-driven three- dimensional deformable bubbles. The computational results with this volume-amending method in-corporated are in good agreement with the reported experimental data and the mass is well preserved in all cases.
基金supported by the US National Science Foundation(NSF)through the grant DMS-0451466 and DMS-0811259by the US Department of Energy through the grant DE-FG02-05ER25707+2 种基金supported by the NSF Center for Theoretical Biological Physics(CTBP)under the NSF grant PHY-0822283the grant Award Number R01GM096188 from the National Institute of General Medical Sciences(NIGMS)the National Institutes of Health(NIH).
文摘A new finite element level set method is developed to simulate the interface motion.The normal velocity of the moving interface can depend on both the local geometry,such as the curvature,and the external force such as that due to the flux from both sides of the interface of a material whose concentration is governed by a diffusion equation.The key idea of the method is to use an interface-fitted finite element mesh.Such an approximation of the interface allows an accurate calculation of the solution to the diffusion equation.The interface-fitted mesh is constructed from a base mesh,a uniform finite element mesh,at each time step to explicitly locate the interface and separate regions defined by the interface.Several new level set techniques are developed in the framework of finite element methods.These include a simple finite element method for approximating the curvature,a new method for the extension of normal velocity,and a finite element least-squares method for the reinitialization of level set functions.Application of the method to the classical solidification problem captures the dendrites.The method is also applied to the molecular solvation to determine optimal solute-solvent interfaces of solvation systems.
