In this paper,we shall study structures of even lattice vertex operator algebras by using the geometry of the varieties of their semi-conformal vectors.We first give the varieties of semi-conformal vectors of a family...In this paper,we shall study structures of even lattice vertex operator algebras by using the geometry of the varieties of their semi-conformal vectors.We first give the varieties of semi-conformal vectors of a family of vertex operator algebras V_(√kA_(1)) associated to rank-one positive definite even lattices √kA_(1) for arbitrary positive integers k to characterize these even lattice vertex operator algebras.In such a family of lattice vertex operator algebras V_(√kA_(1)),the vertex operator algebra V_(√2A_(1)) is different from others.Hence we describe the varieties of semi-conformal vectors of V_(√2A_(1)) and the fixed vertex operator subalgebra V^(+)√2A_(1).Moreover,as applications,we study the relations between vertex operator algebras V_(√kA_(1) )and L_(sl_(2))(k,0)for arbitrary positive integers k by the viewpoint of semi-conformal homomorphisms of vertex operator algebras.For case k=2,in the series of rational simple affine vertex operator algebras L_(sl_(2))(k,0)for positive integers k,we show that L_(sl_(2))(2,0)is a unique frame vertex operator algebra with rank 3.展开更多
Introduction: Breech birth has always been a subject of great interest because of its risks of perinatal morbidity and mortality. Aim: The aim of our study was to compare the maternal and perinatal prognosis of breech...Introduction: Breech birth has always been a subject of great interest because of its risks of perinatal morbidity and mortality. Aim: The aim of our study was to compare the maternal and perinatal prognosis of breech delivery with that of vertex delivery. Patients and Method: This was a retrospective case-control analytical study carried out in the obstetrics and gynaecology department of Ségou hospital over a 2-year period from 1 January 2020 to 31 December 2021, involving 242 breech deliveries compared with 484 top deliveries with a live single foetus without foetal malformation of gestational age ≥ 35 SA. The statistical tests used were: chi² (p Results: The frequency of breech delivery was 3.3%, with a predominance of caesarean section for breech presentation (64.88%) compared with 32.85% for vertex (P: 0.00;CI: (0.191 - 0.367). The perinatal prognosis of fetuses with breech presentations was marked by a higher rate of neonatal asphyxia (Apgar score Conclusion: Breech birth is relatively rare in our department. It carries a higher risk of maternal morbidity and neonatal morbidity than breech delivery. However, the vital prognosis for the mother was identical in both groups.展开更多
A kinetic 5-vertex model is used to investigate hexagon-islands formation on growing single-walled carbon nanotubes (SWCNT). In the model, carbon atoms adsorption and migration processes on the SWCNT edge are consider...A kinetic 5-vertex model is used to investigate hexagon-islands formation on growing single-walled carbon nanotubes (SWCNT). In the model, carbon atoms adsorption and migration processes on the SWCNT edge are considered. These two dynamic processes are assumed to be mutually independent as well as mutually dependent as far as the whole growth of the nanotube is concerned. Key physical parameters of the model are the growth time t, the diffusion length Γ defined as the ratio of the diffusion rate D to the carbon atomic flux F and the SWCNT chiral angle. The kinetic equation that describes the nanotube edge dynamics is solved using kinetic Monte Carlo simulations with the Bortz, Kalos and Lebowitz update algorithm. The behaviors of islands density and size distribution are investigated within the growth parameters’ space. Our study revealed key mechanisms that enable the formation of a new ring of hexagons at the SWCNT edge. The growth occurs either by pre-existing steps propagation or by hexagon-islands growth and coalescence on terraces located between dislocation steps, depending on values of model parameters. This should offer a road map for edge design in nanotubes production. We also found that in appropriate growth conditions, the islands density follows Gaussian and generalized Wigner distributions whereas their size distribution at a given growth time shows a decreasing exponential trend.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.12475002).
文摘In this paper,we shall study structures of even lattice vertex operator algebras by using the geometry of the varieties of their semi-conformal vectors.We first give the varieties of semi-conformal vectors of a family of vertex operator algebras V_(√kA_(1)) associated to rank-one positive definite even lattices √kA_(1) for arbitrary positive integers k to characterize these even lattice vertex operator algebras.In such a family of lattice vertex operator algebras V_(√kA_(1)),the vertex operator algebra V_(√2A_(1)) is different from others.Hence we describe the varieties of semi-conformal vectors of V_(√2A_(1)) and the fixed vertex operator subalgebra V^(+)√2A_(1).Moreover,as applications,we study the relations between vertex operator algebras V_(√kA_(1) )and L_(sl_(2))(k,0)for arbitrary positive integers k by the viewpoint of semi-conformal homomorphisms of vertex operator algebras.For case k=2,in the series of rational simple affine vertex operator algebras L_(sl_(2))(k,0)for positive integers k,we show that L_(sl_(2))(2,0)is a unique frame vertex operator algebra with rank 3.
文摘Introduction: Breech birth has always been a subject of great interest because of its risks of perinatal morbidity and mortality. Aim: The aim of our study was to compare the maternal and perinatal prognosis of breech delivery with that of vertex delivery. Patients and Method: This was a retrospective case-control analytical study carried out in the obstetrics and gynaecology department of Ségou hospital over a 2-year period from 1 January 2020 to 31 December 2021, involving 242 breech deliveries compared with 484 top deliveries with a live single foetus without foetal malformation of gestational age ≥ 35 SA. The statistical tests used were: chi² (p Results: The frequency of breech delivery was 3.3%, with a predominance of caesarean section for breech presentation (64.88%) compared with 32.85% for vertex (P: 0.00;CI: (0.191 - 0.367). The perinatal prognosis of fetuses with breech presentations was marked by a higher rate of neonatal asphyxia (Apgar score Conclusion: Breech birth is relatively rare in our department. It carries a higher risk of maternal morbidity and neonatal morbidity than breech delivery. However, the vital prognosis for the mother was identical in both groups.
文摘A kinetic 5-vertex model is used to investigate hexagon-islands formation on growing single-walled carbon nanotubes (SWCNT). In the model, carbon atoms adsorption and migration processes on the SWCNT edge are considered. These two dynamic processes are assumed to be mutually independent as well as mutually dependent as far as the whole growth of the nanotube is concerned. Key physical parameters of the model are the growth time t, the diffusion length Γ defined as the ratio of the diffusion rate D to the carbon atomic flux F and the SWCNT chiral angle. The kinetic equation that describes the nanotube edge dynamics is solved using kinetic Monte Carlo simulations with the Bortz, Kalos and Lebowitz update algorithm. The behaviors of islands density and size distribution are investigated within the growth parameters’ space. Our study revealed key mechanisms that enable the formation of a new ring of hexagons at the SWCNT edge. The growth occurs either by pre-existing steps propagation or by hexagon-islands growth and coalescence on terraces located between dislocation steps, depending on values of model parameters. This should offer a road map for edge design in nanotubes production. We also found that in appropriate growth conditions, the islands density follows Gaussian and generalized Wigner distributions whereas their size distribution at a given growth time shows a decreasing exponential trend.
