An automatic procedure for building a protein polyalanine backbone from guiding alpha-carbon positions is presented here,which is different from a previously developed'spare parts'approach(Jones and Thirup,198...An automatic procedure for building a protein polyalanine backbone from guiding alpha-carbon positions is presented here,which is different from a previously developed'spare parts'approach(Jones and Thirup,1986;Claessens et al.,1989). In our procedure,the geometric restraint of angle N-CA-C is used to generate a list of polypeptide chains,and several filters are used later to select the best conformer.The most important filter is based upon the Ramachandran scatter plot of mainchain dihedral angles PHI and PSI.Results for all test cases are satisfactory,with more than 95%of peptide planes correctly reconstructed and the overall root-mean-square deviation less than 0.5 angstrom compared with the refined X-ray coordinates.展开更多
AIM：To represent mathematically the intersection between the ectatic corneal geometry and the plane of intracorneal ring implants（ICRS）in order to determine the corneal response to ICRS surgery in keratoconus（KC）...AIM：To represent mathematically the intersection between the ectatic corneal geometry and the plane of intracorneal ring implants（ICRS）in order to determine the corneal response to ICRS surgery in keratoconus（KC）.Thereafter,to present the concept and early results of a newly derived topography-guided nomogram for ICRS surgery for the treatment of keratectasia. METHODS：The corneal rings plane intersection was modelled to a conic section. Ring effect was the result of：the ring size,position（steep vs flat）,location（distance from the geometric centre of the cornea）,and the discrepancy between the ring＇s curvature and the tunnel＇s curvature.Femtosecond laser was used to create the tunnels and the incision sites were chosen according to the nomogram in order to place the thickest ring in the steepest portion of the cornea regardless of the astigmatism axis of refraction.RESULTS：The conic section had a more prolate shape in the steep area of the cornea than in the flat area,depending on the corneal sagittal curvature. Equal ring size had more flattening effect in the steep area than in the flat area. Thick segment should be implanted under the steep portion of the cornea regardless of the cylinder axis of refraction. Single segment in the steep area was sufficient in early and moderate cases of KC. The new nomogram provided more topographic regularity with significant reduction of astigmatism and better improvement in uncorrected visual acuity（UCVA）and best-corrected visual acuity（BCVA）than the conventional nomogram. CONCLUSION：The newly derived nomogram can produce better results than the conventional nomogram. Moreover,based on this concept,a new nomogram can be integrated into the femtosecond laser software to create topography-guided,customized,elliptical tunnels with modified focal asphericity that allows for customized focal flattening of the irregularly steepened ectatic cornea.展开更多
文摘An automatic procedure for building a protein polyalanine backbone from guiding alpha-carbon positions is presented here,which is different from a previously developed'spare parts'approach(Jones and Thirup,1986;Claessens et al.,1989). In our procedure,the geometric restraint of angle N-CA-C is used to generate a list of polypeptide chains,and several filters are used later to select the best conformer.The most important filter is based upon the Ramachandran scatter plot of mainchain dihedral angles PHI and PSI.Results for all test cases are satisfactory,with more than 95%of peptide planes correctly reconstructed and the overall root-mean-square deviation less than 0.5 angstrom compared with the refined X-ray coordinates.
文摘AIM：To represent mathematically the intersection between the ectatic corneal geometry and the plane of intracorneal ring implants（ICRS）in order to determine the corneal response to ICRS surgery in keratoconus（KC）.Thereafter,to present the concept and early results of a newly derived topography-guided nomogram for ICRS surgery for the treatment of keratectasia. METHODS：The corneal rings plane intersection was modelled to a conic section. Ring effect was the result of：the ring size,position（steep vs flat）,location（distance from the geometric centre of the cornea）,and the discrepancy between the ring＇s curvature and the tunnel＇s curvature.Femtosecond laser was used to create the tunnels and the incision sites were chosen according to the nomogram in order to place the thickest ring in the steepest portion of the cornea regardless of the astigmatism axis of refraction.RESULTS：The conic section had a more prolate shape in the steep area of the cornea than in the flat area,depending on the corneal sagittal curvature. Equal ring size had more flattening effect in the steep area than in the flat area. Thick segment should be implanted under the steep portion of the cornea regardless of the cylinder axis of refraction. Single segment in the steep area was sufficient in early and moderate cases of KC. The new nomogram provided more topographic regularity with significant reduction of astigmatism and better improvement in uncorrected visual acuity（UCVA）and best-corrected visual acuity（BCVA）than the conventional nomogram. CONCLUSION：The newly derived nomogram can produce better results than the conventional nomogram. Moreover,based on this concept,a new nomogram can be integrated into the femtosecond laser software to create topography-guided,customized,elliptical tunnels with modified focal asphericity that allows for customized focal flattening of the irregularly steepened ectatic cornea.
