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Increased retinal venule diameter as a prognostic indicator for recurrent cerebrovascular events:a prospective observational study 被引量:1
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作者 Ying Zhao Dawei Dong +5 位作者 Ding Yan Bing Yang Weirong Gui Man Ke Anding Xu Zefeng Tan 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第5期1156-1160,共5页
Microvasculature of the retina is considered an alternative marker of cerebral vascular risk in healthy populations.However,the ability of retinal vasculature changes,specifically focusing on retinal vessel diameter,t... Microvasculature of the retina is considered an alternative marker of cerebral vascular risk in healthy populations.However,the ability of retinal vasculature changes,specifically focusing on retinal vessel diameter,to predict the recurrence of cerebrovascular events in patients with ischemic stroke has not been determined comprehensively.While previous studies have shown a link between retinal vessel diameter and recurrent cerebrovascular events,they have not incorporated this information into a predictive model.Therefore,this study aimed to investigate the relationship between retinal vessel diameter and subsequent cerebrovascular events in patients with acute ischemic stroke.Additionally,we sought to establish a predictive model by combining retinal veessel diameter with traditional risk factors.We performed a prospective observational study of 141 patients with acute ischemic stroke who were admitted to the First Affiliated Hospital of Jinan University.All of these patients underwent digital retinal imaging within 72 hours of admission and were followed up for 3 years.We found that,after adjusting for related risk factors,patients with acute ischemic stroke with mean arteriolar diameter within 0.5-1.0 disc diameters of the disc margin(MAD_(0.5-1.0DD))of≥74.14μm and mean venular diameter within 0.5-1.0 disc diameters of the disc margin(MVD_(0.5-1.0DD))of≥83.91μm tended to experience recurrent cerebrovascular events.We established three multivariate Cox proportional hazard regression models:model 1 included traditional risk factors,model 2 added MAD_(0.5-1.0DD)to model 1,and model 3 added MVD0.5-1.0DD to model 1.Model 3 had the greatest potential to predict subsequent cerebrovascular events,followed by model 2,and finally model 1.These findings indicate that combining retinal venular or arteriolar diameter with traditional risk factors could improve the prediction of recurrent cerebrovascular events in patients with acute ischemic stroke,and that retinal imaging could be a useful and non-invasive method for identifying high-risk patients who require closer monitoring and more aggressive management. 展开更多
关键词 acute ischemic stroke arteriolar cerebrovascular events diameter digital retinal imaging MICROVASCULATURE prediction RECURRENT RETINA venular
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One-year results for myopia control of orthokeratology with different back optic zone diameters: a randomized trial using a novel multispectral-based topographer 被引量:1
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作者 Wen-Ting Tang Xiang-Ning Luo +4 位作者 Wen-Jing Zhao Jia Liao Xin-Yue Xu Hui-Dan Zhang Li Zhang 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2024年第2期324-330,共7页
AIM:To present the 1-year results of a prospective cohort study investigating the efficacy,potential mechanism,and safety of orthokeratology(ortho-k)with different back optic zone diameters(BOZD)for myopia control in ... AIM:To present the 1-year results of a prospective cohort study investigating the efficacy,potential mechanism,and safety of orthokeratology(ortho-k)with different back optic zone diameters(BOZD)for myopia control in children.METHODS:This randomized clinical study was performed between Dec.2020 and Dec.2021.Participants were randomly assigned to three groups wearing ortho-k:5 mm BOZD(5-MM group),5.5 mm BOZD(5.5-MM group),and 6 mm BOZD(6-MM group).The 1-year data were recorded,including axial length,relative peripheral refraction(RPR,measured by multispectral refractive topography,MRT),and visual quality.The contrast sensitivity(CS)was evaluated by CSV-1000 instrument with spatial frequencies of 3,6,12,and 18 cycles/degree(c/d);the corneal higher-order aberrations(HOAs)were measured by iTrace aberration analyzer.The one-way ANOVA was performed to assess the differences between the three groups.The correlation between the change in AL and RPR was calculated by Pearson’s correlation coefficient.RESULTS:The 1-year results of 20,21,and 21 subjects in the 5-MM,5.5-MM,and 6-MM groups,respectively,were presented.There were no statistical differences in baseline age,sex,or ocular parameters between the three groups(all P>0.05).At the 1-year visit,the 5-MM group had lower axial elongation than the 6-MM group(0.07±0.09 vs 0.18±0.11 mm,P=0.001).The 5-MM group had more myopic total RPR(TRPR,P=0.014),with RPR in the 15°–30°(RPR 15–30,P=0.015),30°–45°(RPR 30–45,P=0.011),temporal(RPR-T,P=0.008),and nasal area(RPR-N,P<0.001)than the 6-MM group.RPR 15–30 in the 5.5-MM group was more myopic than that in the 6-MM group(P=0.002),and RPR-N in the 5-MM group was more myopic than that in the 5.5-MM group(P<0.001).There were positive correlations between the axial elongation and the change in TRPR(r=0.756,P<0.001),RPR 15–30(r=0.364,P=0.004),RPR 30–45(r=0.306,P=0.016),and RPR-N(r=0.253,P=0.047).The CS decreased at 3 c/d(P<0.001),and the corneal HOAs increased in the 5-MM group(P=0.030).CONCLUSION:Ortho-k with 5 mm BOZD can control myopia progression more effectively.The mechanism may be associated with greater myopic shifts in RPR. 展开更多
关键词 relative peripheral refraction ORTHOKERATOLOGY MYOPIA back optic zone diameter axial length multispectral refractive topography
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On Spanning Wide Diameter of Graphs
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作者 WANG Yameng YIMINGJIANG Shabier 《新疆大学学报(自然科学版中英文)》 CAS 2024年第5期571-578,590,共9页
A t-container Ct(u,v)is a set of t internally disjoint paths between two distinct vertices u and v in a graph G,i.e.,Ct(u,v)={P_(1),P_(2),···,Pt}.Moreover,if V(P_(1))∪V(P_(2))∪···∪V(Pt... A t-container Ct(u,v)is a set of t internally disjoint paths between two distinct vertices u and v in a graph G,i.e.,Ct(u,v)={P_(1),P_(2),···,Pt}.Moreover,if V(P_(1))∪V(P_(2))∪···∪V(Pt)=V(G)then Ct(u,v)is called a spanning t-container,denoted by C_(t)^(sc)(u,v).The length of C_(t)^(sc)(u,v)={P_(1),P_(2),···,Pt}is l(C_(t)^(sc)(u,v))=max{l(P_(i))|1≤i≤t}.A graph G is spanning t-connected if there exists a spanning t-container between any two distinct vertices u and v in G.Assume that u and v are two distinct vertices in a spanning t-connected graph G.Let D_(t)^(sc)(u,v)be the collection of all C_(t)^(sc)(u,v)’s.Define the spanning t-wide distance between u and v in G,d_(t)^(sc)(u,v)=min{l(C_(t)^(sc)(u,v))|C_(t)^(sc)(u,v)∈D_(t)^(sc)(u,v)},and the spanning t-wide diameter of G,D_(t)^(sc)(G)=max{d_(t)^(sc)(u,v)|u,v∈V(G)}.In particular,the spanning wide diameter of G is D_(κ)^(sc)(G),whereκis the connectivity of G.In the paper we provide the upper and lower bounds of the spanning wide diameter of a graph,and show that the bounds are best possible.We also determine the exact values of wide diameters of some well known graphs including Harary graphs and generalized Petersen graphs et al.. 展开更多
关键词 CONNECTIVITY spanning connectivity spanning laceability wide diameter spanning wide diameter
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Stable reverse J-shaped diameter distribution occurs in an old-growth karst forest
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作者 Yuanfa Li Jie Li Liting Wei 《Journal of Forestry Research》 SCIE EI CAS CSCD 2024年第6期135-147,共13页
The reverse J-shaped diameter distribution is considered an inherent attribute of natural forests,cru-cial for forest resource utilization and community stability.However,in karst regions,intense habitat heterogeneity... The reverse J-shaped diameter distribution is considered an inherent attribute of natural forests,cru-cial for forest resource utilization and community stability.However,in karst regions,intense habitat heterogeneity might alter species composition,spatial distribution,growth,biomass allocation,and mortality processes,yet its impact on diameter structure remains unclear.A fixed plot of 200 m×110 m was established in the Nanpan River Basin,Southwest China,within an old-growth oak forest(>300 years old),and the influence of site substrates(i.e.,rock and soil),topographic factors,sample area,and orientation on diameter distribution was analyzed.Trees on both rock and soil exhibited a reverse-J shape,quantifiable Project funding:This work was supported by the National Natural Science Foundation of China(32060340 and 31400542),the Scientific Research Capacity Building Project for Laibin Jinxiu Dayaoshan Forest Ecosystem Observation and Research Station of Guangxi(22-035-130-01).through the Weibull function.The substrates had a similar density,approximately 2100 plants/ha.However,the average and range of diameter of trees on rock were smaller than those on soil,suggesting that rock constrains tree growth.The diameter distribution of trees across microtopography also displayed a reverse-J shape.Yet,higher elevations and sunny slopes showed a greater curvature of diameter classes compared to lower elevations and shady slopes,indicating habitat preferences in karst trees.Sample area and orientation had minimal effects on diameter class curve that reached stability when the plot size was 6000 m2.These results suggest that the reverse J-shaped diameter distribution prevails at small scales in karst old-growth forests,encompassing multiple curvatures and spanning forest ecosystems. 展开更多
关键词 Old-growth forest diameter distribution KARST Habitat heterogeneity MICROTOPOGRAPHY
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Effect of a cervical collar on optic nerve sheath diameter in trauma patients
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作者 Mümin Murat Yazici Ozcan Yavasi 《World Journal of Emergency Medicine》 SCIE CAS CSCD 2024年第2期126-130,共5页
BACKGROUND:As advocated in advanced trauma life support and prehospital trauma life support protocols,cervical immobilization is applied until cervical spine injury is excluded.This study aimed to show the difference ... BACKGROUND:As advocated in advanced trauma life support and prehospital trauma life support protocols,cervical immobilization is applied until cervical spine injury is excluded.This study aimed to show the difference in optic nerve sheath diameter(ONSD)between patients with and without a cervical collar using computed tomography(CT).METHODS:This was a single-center,retrospective study examining trauma patients who presented to the emergency department between January 1,2021,and December 31,2021.The ONSD on brain CT of the trauma patients was measured and analyzed to determine whether there was a difference between the ONSD with and without the cervical collar.RESULTS:The study population consisted of 169 patients.On CT imaging of patients with(n=66)and without(n=103)cervical collars,the mean ONSD in the axial plane were 5.43±0.50 mm and 5.04±0.46 mm respectively for the right eye and 5.50±0.52 mm and 5.11±0.46 mm respectively for the left eye.The results revealed an association between the presence of a cervical collar and the mean ONSD,which was statistically significant(P<0.001)for both the right and left eyes.CONCLUSION:A cervical collar may be associated with increased ONSD.The effect of this increase in the ONSD on clinical outcomes needs to be investigated,and the actual need for cervical collar in the emergency department should be evaluated on a case-by-case basis. 展开更多
关键词 Optic nerve sheath diameter Computed tomography TRAUMA Emergency medicine
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Added value of ratio of cross diameters of the appendix in ultrasound diagnosis of acute appendicitis
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作者 Feng-Wa Gu Si-Ze Wu 《World Journal of Gastrointestinal Surgery》 SCIE 2024年第1期21-28,共8页
BACKGROUND The maximum outer diameter(MOD)of the appendix is an essential parameter for diagnosing acute appendicitis,but there is space for improvement in ultrasound(US)diagnostic performance.AIM To investigate wheth... BACKGROUND The maximum outer diameter(MOD)of the appendix is an essential parameter for diagnosing acute appendicitis,but there is space for improvement in ultrasound(US)diagnostic performance.AIM To investigate whether combining the ratio of the cross diameters(RATIO)of the appendix with MOD of the appendix can enhance the diagnostic performance of acute appendicitis.METHODS A retrospective study was conducted,and medical records of 233 patients with acute appendicitis and 112 patients with a normal appendix were reviewed.The MOD and RATIO of the appendix were calculated and tested for their diagnostic performance of acute appendicitis,both individually and in combination.RESULTS The RATIO for a normal appendix was 1.32±0.16,while for acute appendicitis it was 1.09±0.07.The cut-off value for RATIO was determined to be≤1.18.The area under the receiver operating characteristic curve(AUC)for diagnosing acute appendicitis using RATIO≤1.18 and MOD>6 mm was 0.870 and 0.652,respectively.There was a significant difference in AUC between RATIO≤1.18 and MOD>6 mm(P<0.0001).When comparing the combination of RATIO≤1.18 and MOD>6 mm with MOD>6 mm alone,the combination showed increased specificity,positive predictive value(PPV),and AUC.However,the sensitivity and negative predictive value decreased.CONCLUSION Combining RATIO of the appendix≤1.18 and MOD>6 mm can significantly improve the specificity,PPV,and AUC in the US diagnosis of acute appendicitis. 展开更多
关键词 Acute appendicitis diameter RATIO Diagnosis ULTRASOUND
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Fuzzy Control Optimization of Loading Paths for Hydroforming of Variable Diameter Tubes
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作者 Yong Xu Xuewei Zhang +4 位作者 Wenlong Xie Shihong Zhang Xinyue Huang Yaqiang Tian Liansheng Chen 《Computers, Materials & Continua》 SCIE EI 2024年第11期2753-2768,共16页
The design of the loading path is one of the important research contents of the tube hydroforming process.Optimization of loading paths using optimization algorithms has received attention due to the inefficiency of o... The design of the loading path is one of the important research contents of the tube hydroforming process.Optimization of loading paths using optimization algorithms has received attention due to the inefficiency of only finite element optimization.In this paper,the hydroforming process of 5A02 aluminum alloy variable diameter tube was as the research object.Fuzzy control was used to optimize the loading path,and the fuzzy rule base was established based on FEM.The minimum wall thickness and wall thickness reduction rate were determined as input membership functions,and the axial feeds variable value of the next step was used as output membership functions.The results show that the optimized loading path greatly improves the uniformity of wall thickness and the forming effect compared with the linear loading path.The round corner lamination rate of the tube is 91.2%under the fuzzy control optimized loading path,which was increased by 47.1%and 22.6%compared with linear loading Path 1 and Path 2,respectively.Based on the optimized loading path in the experiment,the minimum wall thickness of the variable diameter tube was 1.32 mm and the maximum thinning rate was 12.4%.The experimental results were consistent with the simulation results,which verified the accuracy of fuzzy control.The research results provide a reference for improving the forming quality of thin-walled tubes and plates. 展开更多
关键词 Variable diameter tubes finite element simulation HYDROFORMING fuzzy control
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Simulation of Haloxylon Ammodendron Stand Basic Diameter Structure Based on Fuzzy Distribution Function
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作者 Shaohua Wang Chuanqiang Liu Ting Yang 《Agricultural Sciences》 2024年第1期132-145,共14页
Based on the investigation data of 12 Haloxylon ammodendron plots in the south edge of Gurbantunggut Desert, Fuzzy distribution was introduced into the study of Haloxylon ammodendron base diameter structure fitting ac... Based on the investigation data of 12 Haloxylon ammodendron plots in the south edge of Gurbantunggut Desert, Fuzzy distribution was introduced into the study of Haloxylon ammodendron base diameter structure fitting according to the consistency between the characteristics of Fuzzy distribution function and the distribution series of cumulative percentage of stand base diameter, and the fitting precision and effect of Fuzzy distribution function were discussed. The root mean square error RMSE and determination coefficient R<sup>2</sup> values showed that Fuzzy-Γ<sub>1</sub>, Fuzzy-Γ<sub>2</sub>, Fuzzy-Γ<sub>3</sub>, Fuzzy-Γ<sub>4</sub> had good fitting performance, among which Fuzzy-Γ<sub>1</sub> had relatively high fitting precision, and its parameters were closely related to stand age and density, Fuzzy-Γ<sub>2</sub> distribution function was the second, and Fuzzy-Γ<sub>4</sub> distribution function had the worst fitting effect. By introducing a parameter c from the similarity of four distribution function formulas, a generalized Fuzzy distribution function Fuzzy-Γ<sub>5</sub> is obtained. This function shows the highest fitting accuracy. Most of the values of parameter c are near 1 or 2, which shows that the diameter distribution is mainly approximate to Fuzzy-Γ<sub>1</sub> and Fuzzy-Γ<sub>2</sub>. 展开更多
关键词 Fuzzy Distribution Function Haloxylon Ammodendron Base diameter Distribution Stand Factor
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An evaluation of ureteral diameter ratio and vesicoureteral reflux index in the treatment of primary vesicoureteral reflux
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作者 Yusuf Atakan Baltrak Nebil Akdogan +3 位作者 Mutlu Deger Volkan Izol Ibrahim Atilla Aridogan Nihat Satar 《Asian Journal of Urology》 CSCD 2024年第3期437-442,共6页
Objective:Vesicoureteral reflux(VUR)index is a simple,validated tool that reliably predicts significant improvement and spontaneous resolution of primary reflux in children.The aim of this study was to evaluate and co... Objective:Vesicoureteral reflux(VUR)index is a simple,validated tool that reliably predicts significant improvement and spontaneous resolution of primary reflux in children.The aim of this study was to evaluate and compare the ureter diameter ratio(UDR)and VUR index(VURx)of patients treated with endoscopic injection(EI)and ureteroneocystostomy(UNC)methods in the pediatric age group due to primary VUR.Methods:Patients under the age of 18 years old who underwent EI and UNC with the diagnosis of primary VUR between January 2011 and September 2021 were determined as the participants.The UDR was assessed using voiding cystourethrography,and the VURx score was determined prior to treatment based on hospital records included in the study.Results:A total of 255 patients,60(23.5%)boys and 195(76.5%)girls,with a mean age of 76.5(range 13.0e204.0)months,were included in the study.EI was applied to 130(51.0%)patients and UNC was applied to 125(49.0%)patients due to primary VUR.The optimum cut-off for the distal UDR was obtained as 0.17 with sensitivity and specificity of 73.0%and 63.0%,respectively.The positive and negative predictive values were 66.0%and 70.0%,respectively.Conclusion:When the UDR and VURx score are evaluated together for the surgical treatment of primary VUR in the pediatric age group,it is thought that it may be useful in predicting the clinical course of the disease and evaluating surgical treatment options. 展开更多
关键词 Distal ureter diameter ratio Vesicoureteral reflux Vesicoureteral reflux index management Vesicoureteral reflux index
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Platelet counts to spleen diameter ratio:A promising noninvasive tool for predicting esophageal varices in cirrhosis patients
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作者 Getnet Yigzaw Mossie Abdulsemed Mohammed Nur +2 位作者 Zekarias Seifu Ayalew Gebeyehu Tessema Azibte Kaleb Assefa Berhane 《World Journal of Hepatology》 2024年第10期1177-1187,共11页
BACKGROUND Liver cirrhosis is the end stage of progressive liver fibrosis as a consequence of chronic liver inflammation,wherein the standard hepatic architecture is replaced by regenerative hepatic nodules,which even... BACKGROUND Liver cirrhosis is the end stage of progressive liver fibrosis as a consequence of chronic liver inflammation,wherein the standard hepatic architecture is replaced by regenerative hepatic nodules,which eventually lead to liver failure.Cirrhosis without any symptoms is referred to as compensated cirrhosis.Complications such as ascites,variceal bleeding,and hepatic encephalopathy indicate the onset of decompensated cirrhosis.Gastroesophageal varices are the hallmark of clini-cally significant portal hypertension.AIM To determine the accuracy of the platelet count-to-spleen diameter(PC/SD)ratio to evaluate esophageal varices(EV)in patients with cirrhosis.METHODS This retrospective observational study was conducted at Tikur Anbessa Specia-lized Hospital and Adera Medical Center from January 1,2019,to December 30,2023.Data were collected via chart review and direct patient interviews using structured questionnaires.The data were exported to the SPSS software version 26 for analysis and clearance.A receiver operating characteristic curve was plotted for splenic diameter,platelet count,and PC/SD ratio to obtain sensitivity,speci-ficity,positive predictive value,negative predictive value,positive likelihood ratio,and negative likelihood ratio.RESULTS Of the 140 participants,67%were men.Hepatitis B(38%)was the most common cause of cirrhosis,followed by cryptogenic cirrhosis(28%)and hepatitis C(16%).Approximately 83.6%of the participants had endoscopic evidence of EV,whereas 51.1%had gastric varices.Decompensated cirrhosis and PC were associated with the presence of EV with adjusted odds ratios of 12.63(95%CI:3.16-67.58,P=0.001)and 0.14(95%CI:0.037-0.52,P=0.004),respectively.A PC/SD ratio<1119 had a sensitivity of 86.32%and specificity of 70%with area under the curve of 0.835(95%CI:0.736-0.934,P<0.001).CONCLUSION A PC/SD ratio<1119 predicts EV in patients with cirrhosis.It is a valuable,noninvasive tool for EV risk assess-ment in resource-limited settings. 展开更多
关键词 Cirrhosis Esophageal varices Portal hypertension Platelet count Splenic diameter
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Study of the Characteristics of Large-Diameter Iron Bars Obtained by Rolling at the ODHAV Foundry in the Republic of Guinea
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作者 Alpha Issa Diallo Jean Ahmadou Kourouma +3 位作者 Adama Moussa Sakho Younoussa Moussa Baldé Mamadou Madaniou Sow Alexandre Lucien Richard 《Journal of Materials Science and Chemical Engineering》 2024年第6期43-54,共12页
This work consists of evaluating the quality of the mechanical parameters of large-diameter steels, i.e. 20, 25, 28 and 32, through a process of recycling scrap metal that fills garages, rubbish dumps, gutters and oth... This work consists of evaluating the quality of the mechanical parameters of large-diameter steels, i.e. 20, 25, 28 and 32, through a process of recycling scrap metal that fills garages, rubbish dumps, gutters and other abandoned sites, as well as imported concrete reinforcing steel sold in the Republic of Guinea. To carry out this important work, a number of mechanical tensile and bending tests and a microscopic analysis combining two devices, an electron microscope and a photographic camera, were carried out. The samples were taken from sampling areas in the major communes of Conakry, namely: Casse Sonfonia, Matoto and Kagbélen. The tensile strength values of the large dimensions 20, 25, 28 and 32 are given in the tables. 展开更多
关键词 Recycled Scrap Large diameter ROLLING Tensile Testing BENDING
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Optic nerve sheath diameters in nontraumatic brain injury:A scoping review and role in the intensive care unit
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作者 Madhura Bhide Deven Juneja +1 位作者 Omender Singh Shakya Mohanty 《World Journal of Critical Care Medicine》 2024年第3期75-90,共16页
BACKGROUND Neuromonitoring in medical intensive care units is challenging as most patients are unfit for invasive intracranial pressure(ICP)modalities or unstable to transport for imaging.Ultrasonography-based optic n... BACKGROUND Neuromonitoring in medical intensive care units is challenging as most patients are unfit for invasive intracranial pressure(ICP)modalities or unstable to transport for imaging.Ultrasonography-based optic nerve sheath diameter(ONSD)is an attractive option as it is reliable,repeatable and easily performed at the bedside.It has been sufficiently validated in traumatic brain injury(TBI)to be incorporated into the guidelines.However,currently the data for non-TBI patients is inconsistent for a scientific recommendation to be made.AIM To compile the existing evidence for understanding the scope of ONSD in measuring ICP in adult non-traumatic neuro-critical patients.METHODS PubMed,Google Scholar and research citation analysis databases were searched for studies in adult patients with non-traumatic causes of raised ICP.Studies from 2010 to 2024 in English languages were included.RESULTS We found 37 articles relevant to our search.The cutoff for ONSD in predicting ICP varied from 4.1 to 6.3 mm.Most of the articles used cerebrospinal fluid opening pressure followed by raised ICP on computed tomography/magnetic resonance imaging as the comparator parameter.ONSD was also found to be a reliable outcome measure in cases of acute ischaemic stroke,intracerebral bleeding and intracranial infection.However,ONSD is of doubtful utility in septic metabolic encephalopathy,dysnatremias and aneurysmal subarachnoid haemorrhage.CONCLUSION ONSD is a useful tool for the diagnosis of raised ICP in non-traumatic neuro-critically ill patients and may also have a role in the prognostication of a subset of patients. 展开更多
关键词 Intracranial hypertension Intracranial pressure monitoring Medical intensive care unit Neuro-monitoring Nontraumatic brain injury Optic nerve sheath diameter Optic nerve ultrasound
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基于DIAMETER的AAA技术及其在MobileIP中的应用 被引量:5
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作者 朱海龙 张国清 《计算机工程与应用》 CSCD 北大核心 2003年第21期159-163,共5页
首先介绍了AAA的基本概念和体系结构,简要描述了当前主流的AAA协议RADIUS和TACACS+,然后分析了RADIUS的不足,并针对这些缺点详细介绍了下一代AAA协议DIAMETER的协议框架、基本协议和两个重要的扩展,描述了DIAMETER在MobileIP中的应用,... 首先介绍了AAA的基本概念和体系结构,简要描述了当前主流的AAA协议RADIUS和TACACS+,然后分析了RADIUS的不足,并针对这些缺点详细介绍了下一代AAA协议DIAMETER的协议框架、基本协议和两个重要的扩展,描述了DIAMETER在MobileIP中的应用,最后对AAA的发展趋势进行了展望。 展开更多
关键词 AAA技术 diameter 认证 授权 计费 RADIUS TACACS+ MobileIP
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Optimization models of stand structure and selective cutting cycle for large diameter trees of broadleaved forest in Changbai Mountain 被引量:6
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作者 郝清玉 周玉萍 +1 位作者 王立海 吴金卓 《Journal of Forestry Research》 SCIE CAS CSCD 2006年第2期135-140,共6页
The optimum models of harvesting yield and net profits of large diameter trees for broadleaved forest were developed, of which include matrix growth sub-model, harvesting cost and wood price sub-models, based on the d... The optimum models of harvesting yield and net profits of large diameter trees for broadleaved forest were developed, of which include matrix growth sub-model, harvesting cost and wood price sub-models, based on the data from Hongshi Forestry Bureau, in Changbai Mountain region, Jilin Province, China. The data were measured in 232 permanent sample plots. With the data of permanent sample plots, the parameters of transition probability and ingrowth models were estimated, and some models were compared and partly modified. During the simulation of stand structure, four factors such as largest diameter residual tree (LDT), the ratio of the number of trees in a given diameter class to those in the next larger diameter class (q), residual basal area (RBA) and selective cutting cycle (C) were considered. The simulation results showed that the optimum stand structure parameters for large diameter trees are as follows: q is 1.2, LDT is 46cm, RBA is larger than 26 m^2 and selective cutting cycle time (C) is between 10 and 20 years. 展开更多
关键词 Large diameter tree Stand structure OPTIMIZATION Broad-leaved forest MODEL
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基于改进的Diameter/EAP-MD5的SWIM认证方法 被引量:4
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作者 吴志军 赵婷 雷缙 《通信学报》 EI CSCD 北大核心 2014年第8期1-7,共7页
广域信息管理(SWIM,system wide information management)采用面向服务的体系结构(SOA,service oriented architecture)提供民航信息交互与数据共享功能。在分析SWIM体系结构和基于Diameter协议的EAP-MD5应用子协议基础上,给出标准Diame... 广域信息管理(SWIM,system wide information management)采用面向服务的体系结构(SOA,service oriented architecture)提供民航信息交互与数据共享功能。在分析SWIM体系结构和基于Diameter协议的EAP-MD5应用子协议基础上,给出标准Diameter/EAP-MD5认证过程中存在的安全隐患,改进了EAP-MD5认证协议,提出基于改进的Diameter/EAP-MD5协议的SWIM用户身份认证方法,研究基于Diameter的SWIM认证服务,并在模拟的SWIM环境中对改进方法进行仿真实验和安全性分析。实验结果表明,改进的Diameter/EAP-MD5认证方法可在计算性能相当的前提下提高SWIM认证系统的安全性,为SWIM安全服务框架的构建提供保障。 展开更多
关键词 广域信息管理系统 diameter协议 扩展认证协议 信息—摘要算法 身份认证
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Diameter协议研究 被引量:6
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作者 邱锡鹏 刘海鹏 《计算机科学》 CSCD 北大核心 2003年第2期75-78,共4页
Diameter is the next authentication,authorization and accounting protocol currently developed in the IETF AAA working group ,which will replace the widely and successfully deployed Radius protocol. In the paper ,the m... Diameter is the next authentication,authorization and accounting protocol currently developed in the IETF AAA working group ,which will replace the widely and successfully deployed Radius protocol. In the paper ,the motivations and backgrounds of Diameter protocols are firstly introduced. The following is a detailed description of the Diameter base protocol and its applications,such as mobile IP,NASREQ. Then the comparisons and analysis between Diameter and Radius are given. 展开更多
关键词 diameter协议 TCP/IP协议 AAA协议 计算机网络
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一种集成化的基于Diameter的AAA服务器设计方案 被引量:3
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作者 周贤伟 王淑伟 覃伯平 《计算机应用研究》 CSCD 北大核心 2007年第5期253-255,共3页
在扩展基于Diameter协议的基本AAA服务器系统结构的基础上,提出了一种集成化的基于Diameter协议的AAA服务器设计方案。使用该方案可增强AAA服务器的功能,优化AAA系统结构。通过性能分析,说明集成化设计方案的有效性。
关键词 认证授权和计费 diameter 互联网协议安全 传输层安全
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Diameter在视频监控系统中的应用 被引量:2
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作者 毛柯 石志强 刘琼 《计算机工程与设计》 CSCD 北大核心 2008年第11期2920-2922,2935,共4页
随着视频监控系统的广泛应用,日渐复杂的网络环境使得视频监控系统中的认证、授权和计费服务面临了新的挑战。通过对Diameter协议与RADIUS协议的比较,基于Diameter协议设计了电信级视频监控系统中的AAA服务子系统,实现了支持移动终端访... 随着视频监控系统的广泛应用,日渐复杂的网络环境使得视频监控系统中的认证、授权和计费服务面临了新的挑战。通过对Diameter协议与RADIUS协议的比较,基于Diameter协议设计了电信级视频监控系统中的AAA服务子系统,实现了支持移动终端访问、支持IPv4/IPv6双栈、安全可靠的认证、授权和计费服务,提供了CNGI上的示范应用。 展开更多
关键词 视频监控系统 diameter协议 认证 授权 计费
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基于Diameter的移动IP应用研究 被引量:1
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作者 刘海鹏 王雪平 +1 位作者 郑建立 张根度 《小型微型计算机系统》 CSCD 北大核心 2004年第1期41-44,共4页
首先简述移动 IP的工作原理 ,接着较详细介绍 Diameter基础协议和基于该协议的移动 IP应用 .在此基础上 ,分析和探讨了基于 Diameter的移动 IP应用中仍然存在的一些问题 ,如移动节点在不同外部代理之间的长切换时延 ,并给出相应的解决方... 首先简述移动 IP的工作原理 ,接着较详细介绍 Diameter基础协议和基于该协议的移动 IP应用 .在此基础上 ,分析和探讨了基于 Diameter的移动 IP应用中仍然存在的一些问题 ,如移动节点在不同外部代理之间的长切换时延 ,并给出相应的解决方案 . 展开更多
关键词 移动IP diameter基础协议 基于diameter的移动IP应用 切换时延
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AAA系统中Diameter协议故障恢复算法的改进和实现 被引量:2
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作者 任祥颖 翁睿 凌力 《计算机应用与软件》 CSCD 北大核心 2007年第5期139-142,共4页
在分析AAA系统中Diameter协议的基础上,提出了改进的故障恢复算法,包括故障检测、切换和恢复,进而设计出具体的算法实现方法,并在AAA系统模型中得到验证,增强了系统的稳定性。
关键词 AAA RADIUS diameter协议 故障检测 故障切换 故障恢复
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