Background White matter hyperintensity(WMH)progression is well documented;WMH regression is more contentious,which might reflect differences in defining WMH change.We compared four existing WMH change definitions in o...Background White matter hyperintensity(WMH)progression is well documented;WMH regression is more contentious,which might reflect differences in defining WMH change.We compared four existing WMH change definitions in one population to determine the effect of definition on WMH regression.Methods We recruited patients with minor non-disabling ischaemic stroke who underwent MRI 1-3 months after stroke and 1 year later.We assessed WMH volume(in absolute mL and%intracranial volume)and applied four different definitions,including two thresholds(based on SD or mL),percentile and quintile approaches.Results In 198 participants,mean age 65.5(SD=11.13),baseline WMH volume was 15.46 mL(SD=19.2),the mean net WMH volume change was 0.98 mL(SD=2.84),range-7.98 to+12.84 mL.Proportion regressing/stable/progressing WMH were threshold 1(SD),29.8%/55.6%/14.6%;threshold 2(mL),29.8%/16.7%/53.5%;percentile approach,28.3%/21.2%/50.5%.The quintile approach includes five groups with quintile 3 reflecting no change(N=40),quintiles 1 and 2 any WMH decrease(N=80)and quintiles 4 and 5 any WMH increase(N=78).Conclusions Different WMH change definitions cause big differences in how participants are categorised;additionally,non-normal WMH distribution precludes use of some definitions.Consistent use of an appropriate definition would facilitate data comparisons,particularly in clinical trials of potential WMH treatments.展开更多
The unified solutions are presented for stresses and displacements around a circular tunnel subjected to a hydrostatic stress field.The rock mass is assumed to be elastic-brittle-plastic and governed by the Unified St...The unified solutions are presented for stresses and displacements around a circular tunnel subjected to a hydrostatic stress field.The rock mass is assumed to be elastic-brittle-plastic and governed by the Unified Strength Theory.The displacements are obtained accounting for three different definitions for elastic strains and different Young's modulus in the plastic zone.The unified solutions obtained in this paper are especially versatile in reflecting the intermediate principal stress effect to different extents for different materials.The conventional solutions,based on the Mohr-Coulomb failure criterion and the Generalized Twin Shear Stress yield criterion,are special cases of the present unified solutions.The new unified solutions can compare with those computed by the latest generalized Hoek-Brown failure criterion.The results obtained demonstrate the importance of the intermediate principal stress influence for the stresses and displacements analysis.The effects of different definitions for elastic strains and different Young's modulus in the plastic zone on the displacements are significant.展开更多
基金Supported by the UK Dementia Research Institute[award number UK DRI-4002]through UK DRI Ltd.Principally funded by the UK Medical Research Council(ACCJ,CA,DJG,JMW)The Row Fogo Centre for Research into Aging and the Brain(ACCJ,CA,DJG,MVH,JMW)+12 种基金the Fondation Leducq Network(16 CVD 05)Stroke Association‘Small Vessel Disease-Spotlight on Symptoms(SVD-SOS)’(SAPG 19n100068)British Heart Foundation(RE/18/5/34216)Alzheimer’s Society(ref 486(AS-CP 18b 001))University of Edinburgh College of Medicine and Veterinary Medicine(ACCJ)Wellcome trust(DJG).Biotechnology and Biological Sciences Research Council,and the Economic and Social Research Council(BB/W008793/1SMM)The Scottish Chief Scientist Office(CAF/18/08UC)Mexican National Council of Science and Technology(CONACYT,2021-000007-01EXTF 00234)the Rowling Clinic(CA).NHS Lothian Research and Development Office(MJT)The Stroke Association(SA PDF 18\100026,SA PDF 23\100007,TSA LECT 2015/04,16 VAD 07SW,MSS,FND).
文摘Background White matter hyperintensity(WMH)progression is well documented;WMH regression is more contentious,which might reflect differences in defining WMH change.We compared four existing WMH change definitions in one population to determine the effect of definition on WMH regression.Methods We recruited patients with minor non-disabling ischaemic stroke who underwent MRI 1-3 months after stroke and 1 year later.We assessed WMH volume(in absolute mL and%intracranial volume)and applied four different definitions,including two thresholds(based on SD or mL),percentile and quintile approaches.Results In 198 participants,mean age 65.5(SD=11.13),baseline WMH volume was 15.46 mL(SD=19.2),the mean net WMH volume change was 0.98 mL(SD=2.84),range-7.98 to+12.84 mL.Proportion regressing/stable/progressing WMH were threshold 1(SD),29.8%/55.6%/14.6%;threshold 2(mL),29.8%/16.7%/53.5%;percentile approach,28.3%/21.2%/50.5%.The quintile approach includes five groups with quintile 3 reflecting no change(N=40),quintiles 1 and 2 any WMH decrease(N=80)and quintiles 4 and 5 any WMH increase(N=78).Conclusions Different WMH change definitions cause big differences in how participants are categorised;additionally,non-normal WMH distribution precludes use of some definitions.Consistent use of an appropriate definition would facilitate data comparisons,particularly in clinical trials of potential WMH treatments.
文摘The unified solutions are presented for stresses and displacements around a circular tunnel subjected to a hydrostatic stress field.The rock mass is assumed to be elastic-brittle-plastic and governed by the Unified Strength Theory.The displacements are obtained accounting for three different definitions for elastic strains and different Young's modulus in the plastic zone.The unified solutions obtained in this paper are especially versatile in reflecting the intermediate principal stress effect to different extents for different materials.The conventional solutions,based on the Mohr-Coulomb failure criterion and the Generalized Twin Shear Stress yield criterion,are special cases of the present unified solutions.The new unified solutions can compare with those computed by the latest generalized Hoek-Brown failure criterion.The results obtained demonstrate the importance of the intermediate principal stress influence for the stresses and displacements analysis.The effects of different definitions for elastic strains and different Young's modulus in the plastic zone on the displacements are significant.
