Cerebrovascular pressure reactivity monitoring using wavelet analysis in traumatic brain injury patients: A retrospective study

Liu, Xiuyun,Donnelly, Joseph,Czosnyka, Marek,Aries, Marcel J. H.,Brady, Ken,Cardim, Danilo,Robba, Chiara,Cabeleira, Manuel,Kim, Dong-Joo,Haubrich, Christina,Hutchinson, Peter J.,Smielewski, Peter Public Library of Science 2017 PLoS medicine Vol.14 No.7

<▼1><P><B>Background</B></P><P>After traumatic brain injury (TBI), the ability of cerebral vessels to appropriately react to changes in arterial blood pressure (pressure reactivity) is impaired, leaving patients vulnerable to cerebral hypo- or hyperperfusion. Although, the traditional pressure reactivity index (PRx) has demonstrated that impaired pressure reactivity is associated with poor patient outcome, PRx is sometimes erratic and may not be reliable in various clinical circumstances. Here, we introduce a more robust transform-based wavelet pressure reactivity index (wPRx) and compare its performance with the widely used traditional PRx across 3 areas: its stability and reliability in time, its ability to give an optimal cerebral perfusion pressure (CPPopt) recommendation, and its relationship with patient outcome.</P><P><B>Methods and findings</B></P><P>Five hundred and fifteen patients with TBI admitted in Addenbrooke’s Hospital, United Kingdom (March 23rd, 2003 through December 9th, 2014), with continuous monitoring of arterial blood pressure (ABP) and intracranial pressure (ICP), were retrospectively analyzed to calculate the traditional PRx and a novel wavelet transform-based wPRx. wPRx was calculated by taking the cosine of the wavelet transform phase-shift between ABP and ICP. A time trend of CPPopt was calculated using an automated curve-fitting method that determined the cerebral perfusion pressure (CPP) at which the pressure reactivity (PRx or wPRx) was most efficient (CPPopt_PRx and CPPopt_wPRx, respectively).</P><P>There was a significantly positive relationship between PRx and wPRx (r = 0.73), and wavelet wPRx was more reliable in time (ratio of between-hour variance to total variance, wPRx 0.957 ± 0.0032 versus PRx and 0.949 ± 0.047 for PRx, <I>p</I> = 0.002). The 2-hour interval standard deviation of wPRx (0.19 ± 0.07) was smaller than that of PRx (0.30 ± 0.13, <I>p</I> < 0.001). wPRx performed better in distinguishing between mortality and survival (the area under the receiver operating characteristic [ROC] curve [AUROC] for wPRx was 0.73 versus 0.66 for PRx, <I>p</I> = 0.003). The mean difference between the patients’ CPP and their CPPopt was related to outcome for both calculation methods. There was a good relationship between the 2 CPPopts (r = 0.814, <I>p</I> < 0.001). CPPopt_wPRx was more stable than CPPopt_PRx (within patient standard deviation 7.05 ± 3.78 versus 8.45 ± 2.90; <I>p</I> < 0.001).</P><P>Key limitations include that this study is a retrospective analysis and only compared wPRx with PRx in the cohort of patients with TBI. Prior prospective validation is required to better assess clinical utility of this approach.</P><P><B>Conclusions</B></P><P>wPRx offers several advantages to the traditional PRx: it is more stable in time, it yields a more consistent CPPopt recommendation, and, importantly, it has a stronger relationship with patient outcome. The clinical utility of wPRx should be explored in prospective studies of critically injured neurological patients.</P></▼1><▼2><P>Using continuous monitoring data in traumatic brain inury patients, Xiuyun Liu and colleagues compare the performance of cerebrovascular pressure reactivity monitoring using wavelet analysis to the pressure reactivity index.</P></▼2><▼3><P><B>Author summary</B></P><P><B>Why was this study done?</B></P><P>The brain is vulnerable to damage from too little (ischemia) or too much (hyperemia) blood flow following traumatic brain injury (TBI).</P><P>A physiological mechanism called cerebral autoregulation (CA) exists to maintain stable blood flow even if cerebral perfusion pressure (CPP) is changing, and an assessment of CA as part of bedside neuro-monitoring of patients with TBI could facilitate individualized treatment.</P><P>A robust method for assessing CA in TBI is not yet available. The traditional measure used, the pressure reactivity index (PRx), provides inherently noisy estimates and

Design and Analysis of Isolation Effectiveness for Three-dimensional Base-seismic Isolation of Nuclear Island Building

Xiuyun Zhu,Gao Lin,Rong Pan,Jianbo Li 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1

In order to investigate the application of 3D base-seismic isolation system in nuclear power plants(NPPs), comprehensive analysis of constitution and design theory for 3-dimensional combined isolationbearing (3D-CIB) was presented and derived. Four different vertical stiffness of 3D-CIB was designed toisolate the nuclear island (NI) building. This paper aimed at investigating the isolation effectiveness of3D-CIB through modal analysis and dynamic time-history analysis. Numerical results in terms of dynamicresponse of 3D-CIB, relative displacement response, acceleration and floor response spectra (FRS)of the superstructure were compared to validate the reliability of 3D-CIB in mitigating seismic response. The results showed that 3D-CIB can significantly attenuate the horizontal acceleration response, and afair amount of the vertical acceleration response reduction of the upper structure was still observed. 3DCIBplays a significant role in reducing the horizontal and vertical FRS, the vertical FRS basically do notvary with the floor height. The smaller the vertical stiffness of 3D-CIB is, the better the vertical isolationeffectiveness is, whereas, it will increase the displacement and the rocking effect of superstructure. Although the advantage of 3D-CIB is that the vertical stiffness can be flexibly adjusted, it should bedesigned by properly accounting for the balance between the isolation effectiveness and displacementcontrol including rocking effect. The results of this study can provide the technical basis and guidance forthe application of 3D-CIB to engineering structure.

ANALYSIS OF SMOOTHING NEWTON-TYPE METHOD FOR NONLINEAR COMPLEMENTARITY PROBLEMS

Xiuyun Zheng,Hongwei Liu 한국전산응용수학회 2011 Journal of applied mathematics & informatics Vol.29 No.5

In this paper, we consider the smoothing Newton method for the nonlinear complementarity problems with P_0-function. The proposed algorithm is based on a new smoothing function and it needs only to solve one linear system of equations and perform one line search per iteration. Under the condition that the solution set is nonempty and bounded, the proposed algorithm is proved to be convergent globally. Furthermore, the local superlinearly(quadratic) convergence is established under suitable conditions. Preliminary numerical results show that the proposed algorithm is very promising.

Fast position predictive control with current and speed limits for permanent magnet motor systems without weight coefficients

Xiuyun Zhang,Zhiqiang Wang,Genghuang Yang 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.4

To solve the problems that the weight coefficient of the cost function in the traditional position predictive control is difficultto adjust, and the calculation efficiency of the voltage vector selection is low under the traditional ergodic method, this paper proposes a fast position predictive control strategy with current and speed limits without a weight coefficient. First, the reference voltage vector is predicted. Then the cost function is converted to the voltage dimension to leave out the weight coefficient. After that, the candidate vector selection and the cost function optimization are carried out according to the sector location where the reference voltage vector is located to reduce the number of calculations. Then according to actual system needs, the current and speed limits are integrated into the selection of the alternative voltage vector. At this point, the selected optimal voltage vector is improved through the relationship between the voltage limit circle and the rectangular area to realize the current and speed limit. Finally, experimental results verify that the proposed control strategy has better motion control accuracy and dynamic response speed, without adjusting weight coefficients.

The formation and stability of junctions in single-wall carbon nanotubes

Zhang, Xiuyun,Dong, Jichen,Gong, Xiaoshu,Ding, Feng IOP 2018 Nanotechnology Vol.29 No.48

<P>The structure and stability of molecular junctions, which connect two single-wall carbon nanotubes (SWCNTs) of different diameters and chiral angles, (<I>n</I> <SUB>1</SUB>, <I>m</I> <SUB>1</SUB>)-(<I>n</I> <SUB>2</SUB>, <I>m</I> <SUB>2</SUB>), are systematically investigated by density functional tight binding calculations. More than 100 junctions, which connect well-aligned SWCNTs, were constructed and calculated. For a highly stable junction between two chiral (<I>n</I> <SUB>1</SUB>, <I>m</I> <SUB>1</SUB>) and (<I>n</I> <SUB>2</SUB>, <I>m</I> <SUB>2</SUB>) SWCNTs with opposite handedness, the number of pentagon–heptagon (5/7) pairs required to build the junction can be denoted as ∣∣<I>n</I> <SUB>2</SUB>?−?<I>n</I> <SUB>1</SUB>∣?−?∣<I>m</I> <SUB>2</SUB>?−?<I>m</I> <SUB>1</SUB>∣∣+min{∣<I>n</I> <SUB>2</SUB>?−?<I>n</I> <SUB>1</SUB>∣, ∣<I>m</I> <SUB>2</SUB>?−?<I>m</I> <SUB>1</SUB>∣} with (<I>n</I> <SUB>2</SUB>, <I>m</I> <SUB>2</SUB>) rotating <I>π</I>/3 angle or not. While for a junction connected by two zigzag, armchair or two chiral SWCNTs with the same handedness, the number of 5/7 pairs is equal to ∣<I>n</I> <SUB>1</SUB>?−?<I>n</I> <SUB>2</SUB>∣?+?∣<I>m</I> <SUB>1</SUB>?−?<I>m</I> <SUB>2</SUB>∣. Similar to the formation energies of grain boundaries in graphene, the curve of the formation energies vs. chiral angle difference present an ‘M’ shape indicating the preference of ∼30 degree junctions. Moreover, the formation energies of the zigzag-type and armchair-type junctions with zero misorientation angles are largely sensitive to the diameter difference of two sub-SWCNTs.</P>

ANALYSIS OF SMOOTHING NEWTON-TYPE METHOD FOR NONLINEAR COMPLEMENTARITY PROBLEMS

Zheng, Xiuyun The Korean Society for Computational and Applied M 2011 Journal of applied mathematics & informatics Vol.29 No.5

In this paper, we consider the smoothing Newton method for the nonlinear complementarity problems with $P_0$-function. The proposed algorithm is based on a new smoothing function and it needs only to solve one linear system of equations and perform one line search per iteration. Under the condition that the solution set is nonempty and bounded, the proposed algorithm is proved to be convergent globally. Furthermore, the local superlinearly(quadratic) convergence is established under suitable conditions. Preliminary numerical results show that the proposed algorithm is very promising.

Monitoring of Optimal Cerebral Perfusion Pressure in Traumatic Brain Injured Patients Using a Multi-Window Weighting Algorithm

Liu, Xiuyun,Maurits, Natasha M.,Aries, Marcel J.H.,Czosnyka, Marek,Ercole, Ari,Donnelly, Joseph,Cardim, Danilo,Kim, Dong-Joo,Dias, Celeste,Cabeleira, Manuel,Smielewski, Peter Mary Ann Liebert, Inc. Publishers 2017 Journal of Neurotrauma Vol. No.

FINITE GROUPS WITH SOME SEMI-p-COVER-AVOIDING OR ss-QUASINORMAL SUBGROUPS

Qingjun Kong,Xiuyun Guo 대한수학회 2014 대한수학회보 Vol.51 No.4

Suppose that G is a finite group and H is a subgroup of G. H is said to be an ss-quasinormal subgroup of G if there is a subgroup B of G such that G = HB and H permutes with every Sylow subgroup of B; H is said to be semi-p-cover-avoiding in G if there is a chief series 1 = G0 < G1 < · · · < Gt = G of G such that, for every i = 1, 2, . . . , t, if Gi/Gi−1 is a p-chief factor, then H either covers or avoids Gi/Gi−1. We give the structure of a finite group G in which some subgroups of G with prime-power order are either semi-p-cover-avoiding or ss-quasinormal in G. Some known results are generalized.

Analysis of the Construction and Effectiveness of Precision- Targeted Classroom Based on Analysis of Students’ Real Learning Situation

Chao Xiong,Xiuyun Yu,Jiaxin Chen 한국수학교육학회 2022 수학교육연구 Vol.25 No.4

In response to the current educational situation of students’ heavy workload, the author constructs the precision-targeted classroom based on Precision Teaching (PT), Network Pharmacology, and Treatment Based on Syndrome Differentiation. The precision-targeted classroom can solve the current problems of PT and the phenomenon of the heavy academic burden on students, achieve the reduction of the burden and increase the efficiency of education. The precision-targeted classroom includes five key points: targeted goals, childlike thinking, precise intervention, intelligent homework, and stereoscopic evaluation, and the implementation process of the precision-targeted classroom is built from three aspects: before, during and after class. In addition, the author applied it to the actual mathematics classroom to test its teaching effect, and the experimental results showed that: the precision-targeted classroom significantly improved students’ academic performance and thinking level; considerably improved students’ classroom learning status, and facilitated teaching personalization and realized homework quantity control and quality improvement.

Finite $p$-groups in which the normalizer of every non-normal subgroup is contained in its normal closure

Pengfei Bai,Xiuyun Guo,Junxin Wang 대한수학회 2018 대한수학회보 Vol.55 No.6

In this paper, finite $p$-groups $G$ satisfying $N_G(H)\leq H^G$ for every non-normal subgroup $H$ of $G$ are completely classified. This solves a problem proposed by Y. Berkovich.