In this paper, a characterization of all pentavalent arc-transitive graphs is given. It is shown that each pentavalent arc-transitive covering graph F is a regular simple or elementary abelian covering graph. In parti...In this paper, a characterization of all pentavalent arc-transitive graphs is given. It is shown that each pentavalent arc-transitive covering graph F is a regular simple or elementary abelian covering graph. In particular, the elementary abelian covering groups are Z3,Z5or a subgroup of Z2^5.展开更多
Liquid flows in a particular sequence when it is poured out from an open-top receptacle. Since the sequence is hard to catch by experiment, a numerical simulation was performed in this pouring process with the moving ...Liquid flows in a particular sequence when it is poured out from an open-top receptacle. Since the sequence is hard to catch by experiment, a numerical simulation was performed in this pouring process with the moving particle semi-implicit (MPS) method. A modified solid-liquid boundary condition was verified and employed with a new definition of static liquid layers. The whole system was discretized by a set of particles and the liquid particles were marked and tracked in the pouring process. The flowing sequence of the liquid can be calculated by restoring the liquid particles back to their initial positions before it is poured. The mass transfer property is found to depend on the position of the rotation axis and the rotation speed, as well as the viscosity of the liquid. The mechanism of the flowing sequence results from a temporal vortex and its motion during the process. The character vortex is generated by the rotation of the container. The results reveal a principle for a versatile pouring process and may contribute to the applications in flowing control in many fields.展开更多
Background:Surgery in Crohn’s disease(CD)may be associated with poor prognosis and clinical and surgical recurrence.The aim of this study was to describe and compare the post-operative management and outcomes of pati...Background:Surgery in Crohn’s disease(CD)may be associated with poor prognosis and clinical and surgical recurrence.The aim of this study was to describe and compare the post-operative management and outcomes of patients with CD who underwent first vs recurrent surgeries.Methods:Observational study that included adult CD patients from 26 Spanish hospitals who underwent ileocolonic resection with ileocolonic anastomosis between January 2007 and December 2010.Data were retrospectively collected from the medical records.Results:Data from 314 patients were analysed,of whom 262(83%)underwent first surgery and 52(17%)referred to previous CD surgeries.Baseline characteristics were similar between the two groups except for a higher rate of stricturing behavior at diagnosis among re-operated patients(P=0.03).After surgery,a higher proportion of re-operated patients received prophylactic treatment with immunomodulators compared with patients with first surgery(P=0.04).In re-operated patients,time to clinical recurrence was not associated with the fact of receiving or not prophylaxis,whereas,in patients with first surgery,recurrence-free survival was greater when prophylaxis was received(P=0.03).Conclusions:After surgery,a higher proportion of patients with previous surgeries received prophylactic treatment with immunomodulators compared with patients with first surgery.Although prophylactic treatment was beneficial for preventing clinical recurrence in patients operated on for the first time,it did not significantly reduce the risk of further recurrence in patients with previous surgeries.This suggests that effective prophylactic therapies are still needed in this subset of patients.展开更多
文摘In this paper, a characterization of all pentavalent arc-transitive graphs is given. It is shown that each pentavalent arc-transitive covering graph F is a regular simple or elementary abelian covering graph. In particular, the elementary abelian covering groups are Z3,Z5or a subgroup of Z2^5.
基金supported by the National Natural Science Foundation of China (Grant No. 50725621)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20090201110059)
文摘Liquid flows in a particular sequence when it is poured out from an open-top receptacle. Since the sequence is hard to catch by experiment, a numerical simulation was performed in this pouring process with the moving particle semi-implicit (MPS) method. A modified solid-liquid boundary condition was verified and employed with a new definition of static liquid layers. The whole system was discretized by a set of particles and the liquid particles were marked and tracked in the pouring process. The flowing sequence of the liquid can be calculated by restoring the liquid particles back to their initial positions before it is poured. The mass transfer property is found to depend on the position of the rotation axis and the rotation speed, as well as the viscosity of the liquid. The mechanism of the flowing sequence results from a temporal vortex and its motion during the process. The character vortex is generated by the rotation of the container. The results reveal a principle for a versatile pouring process and may contribute to the applications in flowing control in many fields.
基金This study was funded by Merck Sharp&Dohme of Spain,a subsidiary of Merck&Co.,Inc.,Kenilworth,New Jersey,USA.
文摘Background:Surgery in Crohn’s disease(CD)may be associated with poor prognosis and clinical and surgical recurrence.The aim of this study was to describe and compare the post-operative management and outcomes of patients with CD who underwent first vs recurrent surgeries.Methods:Observational study that included adult CD patients from 26 Spanish hospitals who underwent ileocolonic resection with ileocolonic anastomosis between January 2007 and December 2010.Data were retrospectively collected from the medical records.Results:Data from 314 patients were analysed,of whom 262(83%)underwent first surgery and 52(17%)referred to previous CD surgeries.Baseline characteristics were similar between the two groups except for a higher rate of stricturing behavior at diagnosis among re-operated patients(P=0.03).After surgery,a higher proportion of re-operated patients received prophylactic treatment with immunomodulators compared with patients with first surgery(P=0.04).In re-operated patients,time to clinical recurrence was not associated with the fact of receiving or not prophylaxis,whereas,in patients with first surgery,recurrence-free survival was greater when prophylaxis was received(P=0.03).Conclusions:After surgery,a higher proportion of patients with previous surgeries received prophylactic treatment with immunomodulators compared with patients with first surgery.Although prophylactic treatment was beneficial for preventing clinical recurrence in patients operated on for the first time,it did not significantly reduce the risk of further recurrence in patients with previous surgeries.This suggests that effective prophylactic therapies are still needed in this subset of patients.
