We consider the numberπ(x,y;q,a)of primes p≤such that p≡a(mod q)and(p-a)/q is free of prime factors greater than y.Assuming a suitable form of Elliott-Halberstam conjecture,it is proved thatπ(x,y:q,a)is asymptotic...We consider the numberπ(x,y;q,a)of primes p≤such that p≡a(mod q)and(p-a)/q is free of prime factors greater than y.Assuming a suitable form of Elliott-Halberstam conjecture,it is proved thatπ(x,y:q,a)is asymptotic to p(log(x/q)/log y)π(x)/φ(q)on average,subject to certain ranges of y and q,where p is the Dickman function.Moreover,unconditional upper bounds are also obtained via sieve methods.As a typical application,we may control more effectively the number of shifted primes with large prime factors.展开更多
As usual, denote by P(n) the largest prime factor of the integer n 1 with the convention P(1) = 1.For 0 < θ < 1, define Tθ(x) := |{p x : P(p-1) ≥ p~θ}|.In this paper, we obtain a new lower bound for Tθ(x) a...As usual, denote by P(n) the largest prime factor of the integer n 1 with the convention P(1) = 1.For 0 < θ < 1, define Tθ(x) := |{p x : P(p-1) ≥ p~θ}|.In this paper, we obtain a new lower bound for Tθ(x) as x →∞, which improves some recent results of Luca et al.(2015) and Chen and Chen(2017). As a corollary, we partially prove a conjecture of Chen and Chen(2017)about the size of Tθ(x).展开更多
[Objectives]The purpose was to establish an induction system for friable callus of Hedera nepalensis var.sinensis with different parts.[Methods]By screening the most suitable explant and adjusting the hormone ratio of...[Objectives]The purpose was to establish an induction system for friable callus of Hedera nepalensis var.sinensis with different parts.[Methods]By screening the most suitable explant and adjusting the hormone ratio of medium,friable calli of H.nepalensis var.sinensis were induced.[Results]The calli could be induced from leaves,petioles and stem segments,but the ideal explant was stem segments,with induction rate reaching 98%.The optimal medium for callus proliferation was MS+0.5 mg/L KT+1.0 mg/L 2,4-D+30.0 g/L sucrose.After 3-4 generations of subculture on MS+0.5 mg/L BA+1.0 mg/L 2,4-D+30.0 g/L sucrose,favorable friable calli of H.nepalensis var.sinensis were obtained.[Conclusions]The friable calli induced in this experiment can lay a foundation for in-vitro regeneration and cellular secondary metabolite production of H.nepalensis var.sinensis.展开更多
BACKGROUND Screening colonoscopies are routinely performed and have low occurrences of adverse events such as perforation,bleeding,infection,and post-polypectomy syndrome.True device related adverse events are rarely ...BACKGROUND Screening colonoscopies are routinely performed and have low occurrences of adverse events such as perforation,bleeding,infection,and post-polypectomy syndrome.True device related adverse events are rarely reported in the literature.CASE SUMMARY We report a case of a 51-year-old patient without past medical history who presented for her first screening colonoscopy.The patient was thought to have friable mucosa in the cecum and oozed upon water irrigation during screening colonoscopy.It was later identified that the colonoscope used during the index procedure had malfunctioned and produced a pin-point water jet which damaged the colon mucosa of cecum.The maintenance service identified a piece of rubber fragment lodged in the instrument component at the tip of the scope,resulting in high pressure water jet.Repeat colonoscopy with a functioning colonoscope confirmed normal colon mucosa without friability.CONCLUSION This is the first report of mucosa injury from a colonoscope water jet malfunction.Endoscopists should recognize the potential for endoscopic malfunction.展开更多
Based on the geological condition of Zhangxiaolou deep mine in Xuzhou mining area, under 986 m in depth, 20.6-31.6 MPa in maximum horizontal principal stress, and friable and fractured surrounding rock, test researche...Based on the geological condition of Zhangxiaolou deep mine in Xuzhou mining area, under 986 m in depth, 20.6-31.6 MPa in maximum horizontal principal stress, and friable and fractured surrounding rock, test researches on partial relieving pressure were completed for the entry with U-steel arched yielding support. The relieving pressure parameters, technology process and results of springing blasting by boreholes and excavating pockets in the two sides of entry were introduced. It is demonstrated that springing will not be shaped under the condition of single borehole arrangement after exploded, the arrangement by a group, it will make borehole bottom form springing in 0.6-0.8 m in diameter, that convergence of two sides and roof to floor have some increments by using springing blasting for reliving pressure. This kind of method for reliving pressure is not suitable to use in the deep mine, and that the convergence of two sides obviously declined by excavating pocket in two sides, it can be still used in the entry with metal support, while maintenance of entry in deep mines is difficult, and can not be supported by bolt or bolt with wire mesh.展开更多
基金supported by the Programme de Recherche Conjoint CNRS-NSFC(Grant No.1457)supported by National Natural Science Foundation of China(Grant No.11531008)+3 种基金the Ministry of Education of China(Grant No.IRT16R43)the Taishan Scholar Project of Shandong Provincesupported by National Natural Science Foundation of China(Grant No.11601413)NSBRP of Shaanxi Province(Grant No.2017JQ1016)
文摘We consider the numberπ(x,y;q,a)of primes p≤such that p≡a(mod q)and(p-a)/q is free of prime factors greater than y.Assuming a suitable form of Elliott-Halberstam conjecture,it is proved thatπ(x,y:q,a)is asymptotic to p(log(x/q)/log y)π(x)/φ(q)on average,subject to certain ranges of y and q,where p is the Dickman function.Moreover,unconditional upper bounds are also obtained via sieve methods.As a typical application,we may control more effectively the number of shifted primes with large prime factors.
基金supported by Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant No.KJ1601213)
文摘As usual, denote by P(n) the largest prime factor of the integer n 1 with the convention P(1) = 1.For 0 < θ < 1, define Tθ(x) := |{p x : P(p-1) ≥ p~θ}|.In this paper, we obtain a new lower bound for Tθ(x) as x →∞, which improves some recent results of Luca et al.(2015) and Chen and Chen(2017). As a corollary, we partially prove a conjecture of Chen and Chen(2017)about the size of Tθ(x).
基金Tianjin Science and Technology Plan Project(18ZXBFNC00370)Industrial Innovation and Entrepreneurship Team Project of Hebei Province(199A2905H)Fund of Central Government for Guiding Science and Technology Development in Hebei Province(206Z6303G).
文摘[Objectives]The purpose was to establish an induction system for friable callus of Hedera nepalensis var.sinensis with different parts.[Methods]By screening the most suitable explant and adjusting the hormone ratio of medium,friable calli of H.nepalensis var.sinensis were induced.[Results]The calli could be induced from leaves,petioles and stem segments,but the ideal explant was stem segments,with induction rate reaching 98%.The optimal medium for callus proliferation was MS+0.5 mg/L KT+1.0 mg/L 2,4-D+30.0 g/L sucrose.After 3-4 generations of subculture on MS+0.5 mg/L BA+1.0 mg/L 2,4-D+30.0 g/L sucrose,favorable friable calli of H.nepalensis var.sinensis were obtained.[Conclusions]The friable calli induced in this experiment can lay a foundation for in-vitro regeneration and cellular secondary metabolite production of H.nepalensis var.sinensis.
文摘BACKGROUND Screening colonoscopies are routinely performed and have low occurrences of adverse events such as perforation,bleeding,infection,and post-polypectomy syndrome.True device related adverse events are rarely reported in the literature.CASE SUMMARY We report a case of a 51-year-old patient without past medical history who presented for her first screening colonoscopy.The patient was thought to have friable mucosa in the cecum and oozed upon water irrigation during screening colonoscopy.It was later identified that the colonoscope used during the index procedure had malfunctioned and produced a pin-point water jet which damaged the colon mucosa of cecum.The maintenance service identified a piece of rubber fragment lodged in the instrument component at the tip of the scope,resulting in high pressure water jet.Repeat colonoscopy with a functioning colonoscope confirmed normal colon mucosa without friability.CONCLUSION This is the first report of mucosa injury from a colonoscope water jet malfunction.Endoscopists should recognize the potential for endoscopic malfunction.
基金Supported by the Key Project of the National Natural Science Foundation （50490273）
文摘Based on the geological condition of Zhangxiaolou deep mine in Xuzhou mining area, under 986 m in depth, 20.6-31.6 MPa in maximum horizontal principal stress, and friable and fractured surrounding rock, test researches on partial relieving pressure were completed for the entry with U-steel arched yielding support. The relieving pressure parameters, technology process and results of springing blasting by boreholes and excavating pockets in the two sides of entry were introduced. It is demonstrated that springing will not be shaped under the condition of single borehole arrangement after exploded, the arrangement by a group, it will make borehole bottom form springing in 0.6-0.8 m in diameter, that convergence of two sides and roof to floor have some increments by using springing blasting for reliving pressure. This kind of method for reliving pressure is not suitable to use in the deep mine, and that the convergence of two sides obviously declined by excavating pocket in two sides, it can be still used in the entry with metal support, while maintenance of entry in deep mines is difficult, and can not be supported by bolt or bolt with wire mesh.
