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Density of excess modes below the first phonon mode in four-dimensional glasses
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作者 王利近 胥鼎 张世允 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第7期483-489,共7页
Glasses are known to possess low-frequency excess modes beyond the Debye prediction.For decades,it has been assumed that evolution of low-frequency density of excess modes D(ω) with frequency ω follows a power-law s... Glasses are known to possess low-frequency excess modes beyond the Debye prediction.For decades,it has been assumed that evolution of low-frequency density of excess modes D(ω) with frequency ω follows a power-law scaling:D(ω)~ω~γ.However,it remains debated on the value of γ at low frequencies below the first phonon-like mode in finitesize glasses.Early simulation studies reported γ=4 at low frequencies in two-(2D),three-(3D),and four-dimensional(4D)glasses,whereas recent observations in 2D and 3D glasses suggested γ=3.5 in a lower-frequency regime.It is uncertain whether the low-frequency scaling of D(ω)~ω^(3.5) could be generalized to 4D glasses.Here,we conduct numerical simulation studies of excess modes at frequencies below the first phonon-like mode in 4D model glasses.It is found that the system size dependence of D(ω) below the first phonon-like mode varies with spatial dimensions:D(ω) increases in2D glasses but decreases in 3D and 4D glasses as the system size increases.Furthermore,we demonstrate that the ω^(3.5)scaling,rather than the ω~4 scaling,works in the lowest-frequency regime accessed in 4D glasses,regardless of interaction potentials and system sizes examined.Therefore,our findings in 4D glasses,combined with previous results in 2D and 3D glasses,suggest a common low-frequency scaling of D(ω)~ ω^3.5) below the first phonon-like mode across different spatial dimensions,which would inspire further theoretical studies. 展开更多
关键词 vibrational density of states excess modes four-dimensional glasses SCALING computer simulation
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Evaluation of mitral chordae tendineae length using four-dimensional computed
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作者 Takuya Mori Satoshi Matsushita +3 位作者 Terumasa Morita Abulaiti Abudurezake Junji Mochizuki Atsushi Amano 《World Journal of Cardiology》 2024年第5期274-281,共8页
BACKGROUND Mitral valvuloplasty using artificial chordae tendineae represents an effective surgical approach for treating mitral regurgitation.Achieving precise measurements of artificial chordae tendineae length(CL)i... BACKGROUND Mitral valvuloplasty using artificial chordae tendineae represents an effective surgical approach for treating mitral regurgitation.Achieving precise measurements of artificial chordae tendineae length(CL)is an important factor in the procedure;however,no objective index currently exists to facilitate this measurement.Therefore,preoperative assessment of CL is critical for surgical planning and support.Four-dimensional x-ray micro-computed tomography(4D-CT)may be useful for accurate CL measurement considering that it allows for dynamic three-dimensional(3D)evaluation compared to that with transthoracic echocardiography,a conventional inspection method.AIM To investigate the behavior and length of mitral chordae tendineae during systole using 4D-CT.METHODS Eleven adults aged>70 years without mitral valve disease were evaluated.A 64-slice CT scanner was used to capture 20 phases in the cardiac cycle in electrocardiographic synchronization.The length of the primary chordae tendineae was measured from early systole to early diastole using the 3D image.The primary chordae tendineae originating from the anterior papillary muscle and attached to the A1-2 region and those from the posterior papillary muscle and attached to the A2-3 region were designated as cA and cP,respectively.The behavior and maximum lengths[cA(ma),cP(max)]were compared,and the correlation with body surface area(BSA)was evaluated.RESULTS In all cases,the mitral anterior leaflet chordae tendineae could be measured.In most cases,the cA and cP chordae tendineae could be measured visually.The mean cA(max)and cP(max)were 20.2 mm±1.95 mm and 23.5 mm±4.06 mm,respectively.cP(max)was significantly longer.The correlation coefficients(r)with BSA were 0.60 and 0.78 for cA(max)and cP(max),respectively.Both cA and cP exhibited constant variation in CL during systole,with a maximum 1.16-fold increase in cA and a 1.23-fold increase in cP from early to mid-systole.For cP,CL reached a plateau at 15%and remained elongated until end-systole,whereas for cA,after peaking at 15%,CL shortened slightly and then moved toward its peak again as end-systole approached.CONCLUSION The study suggests that 4D-CT is a valuable tool for accurate measurement of both the length and behavior of chordae tendineae within the anterior leaflet of the mitral valve. 展开更多
关键词 Mitral valve Chordae tendineae Computed tomography four-dimensional Cardiac cycle
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Four-dimensional flow magnetic resonance imaging for noninvasive diagnosis of clinically significant portal hypertension and high-risk gastroesophageal varices in patients with cirrhosis
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作者 Jiachen Ji Yi Xiang +12 位作者 Jinghui Dong Hanyu Jiang Tianyi Xia Yunduo Li Mengmeng Zhang Changchun Liu Xijun Gong Bo Jin Wen Shen Gangfeng Zhu Jianming Cai Rui Li Xiaolong Qi 《EngMedicine》 2024年第1期11-18,共8页
Introduction:Noninvasive diagnoses of clinically significant portal hypertension(CSPH)and high-risk gastroesophageal varices are clinically relevant but challenging.Four-dimensional(4D)flow magnetic resonance imaging(... Introduction:Noninvasive diagnoses of clinically significant portal hypertension(CSPH)and high-risk gastroesophageal varices are clinically relevant but challenging.Four-dimensional(4D)flow magnetic resonance imaging(MRI)provides comprehensive flow information and is a promising alternative.This study evaluated the efficacy of 4D flow MRI as a noninvasive method for diagnosing CSPH and high-risk varices in patients with liver cirrhosis.Methods:This prospective study enrolled consecutive patients diagnosed with liver cirrhosis at a tertiary referral center between October 2020 and March 2021.Each participant underwent abdominal 4D flow MRI.Hemodynamic parameters within the portal vein,including the average and peak flow velocities,normalized flow volume(Q_(normal)),and regurgitant fraction(R%),were extracted and compared between healthy individuals and patients with CSPH and between participants with high-and low-risk varices.Subsequently,these parameters were incorporated into a logistic regression(LR)model refined using L1 regularization and validated using five-fold cross-validation.The diagnostic efficacy was evaluated using receiver operating characteristic(ROC)curves.Results:Eighty-two participants were enrolled(71 patients diagnosed with liver cirrhosis and 11 healthy individuals serving as controls).Among hemodynamic parameters,patients with CSPH exhibited a notable increase in Q_(normal)of 0.66±0.19 ml*m^(2)/[cycle*kg](P=0.001)and an R%of 1.98(2.05)(P=0.002).Similarly,patients with high-risk varices showed a higher Q_(normal)of 0.61±0.15 ml*m^(2)/[cycle*kg](P<0.001)and R%of 1.88(2.81)(P=0.006).ROC analysis revealed an area under the curve(AUC)for Q_(normal)of 0.93 and 0.91 for R%for diagnosing CSPH,while the LR model showcased a superior AUC of 0.95.For high-risk varices,Q_(normal)and R%showed AUC values of 0.75 and 0.70,respectively,whereas the LR model showed a higher AUC of 0.84.Conclusion:As a noninvasive imaging modality,4D flow MRI exhibits considerable potential for the diagnosis of CSPH and high-risk gastroesophageal varices;thus,it may minimize the reliance on invasive procedures in patients with cirrhosis. 展开更多
关键词 four-dimensional flow magnetic resonance IMAGING Clinically significant portal hypertension Gastroesophageal varices Hemodynamic parameters Noninvasive diagnosis
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Late effects of the treatment of childhood cancer
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作者 Jelena Roganovic 《World Journal of Clinical Cases》 SCIE 2025年第7期6-12,共7页
Excellent progress has been made in the last few decades in the cure rates of pediatric malignancies,with more than 80%of children with cancer who have access to contemporary treatment being cured.However,the therapie... Excellent progress has been made in the last few decades in the cure rates of pediatric malignancies,with more than 80%of children with cancer who have access to contemporary treatment being cured.However,the therapies responsible for this survival can also produce adverse physical and psychological long-term outcomes,referred to as late effects,which appear months to years after the completion of cancer treatment.Research has shown that 60%to 90%of childhood cancer survivors(CCSs)develop one or more chronic health conditions,and 20%to 80%of survivors experience severe or life-threatening complications during adulthood.Therefore,understanding the late side effects of such treatments is important to improve the health and quality of life of the growing population of CCSs. 展开更多
关键词 SURVIVORSHIP CANCER CHILDREN treatment Late effects
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Pathogenesis, diagnosis, and treatment of epilepsy: electromagnetic stimulation-mediated neuromodulation therapy and new technologies
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作者 Dian Jiao Lai Xu +3 位作者 Zhen Gu Hua Yan Dingding Shen Xiaosong Gu 《Neural Regeneration Research》 SCIE CAS 2025年第4期917-935,共19页
Epilepsy is a severe,relapsing,and multifactorial neurological disorder.Studies regarding the accurate diagnosis,prognosis,and in-depth pathogenesis are crucial for the precise and effective treatment of epilepsy.The ... Epilepsy is a severe,relapsing,and multifactorial neurological disorder.Studies regarding the accurate diagnosis,prognosis,and in-depth pathogenesis are crucial for the precise and effective treatment of epilepsy.The pathogenesis of epilepsy is complex and involves alterations in variables such as gene expression,protein expression,ion channel activity,energy metabolites,and gut microbiota composition.Satisfactory results are lacking for conventional treatments for epilepsy.Surgical resection of lesions,drug therapy,and non-drug interventions are mainly used in clinical practice to treat pain associated with epilepsy.Non-pharmacological treatments,such as a ketogenic diet,gene therapy for nerve regeneration,and neural regulation,are currently areas of research focus.This review provides a comprehensive overview of the pathogenesis,diagnostic methods,and treatments of epilepsy.It also elaborates on the theoretical basis,treatment modes,and effects of invasive nerve stimulation in neurotherapy,including percutaneous vagus nerve stimulation,deep brain electrical stimulation,repetitive nerve electrical stimulation,in addition to non-invasive transcranial magnetic stimulation and transcranial direct current stimulation.Numerous studies have shown that electromagnetic stimulation-mediated neuromodulation therapy can markedly improve neurological function and reduce the frequency of epileptic seizures.Additionally,many new technologies for the diagnosis and treatment of epilepsy are being explored.However,current research is mainly focused on analyzing patients’clinical manifestations and exploring relevant diagnostic and treatment methods to study the pathogenesis at a molecular level,which has led to a lack of consensus regarding the mechanisms related to the disease. 展开更多
关键词 DIAGNOSIS drug treatment ELECTROENCEPHALOGRAPHY epilepsy monitoring EPILEPSY nerve regeneration NEUROSTIMULATION non-drug interventions PATHOGENESIS prediction
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Controversies around the treatment of peritoneal metastases of colorectal cancer
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作者 Francisco J Morera-Ocon Clara Navarro-Campoy +1 位作者 Ticiano Guastella Francisco Landete-Molina 《World Journal of Gastrointestinal Oncology》 SCIE 2025年第1期260-264,共5页
In this editorial we examine the article by Wu et al published in the World Journal of Gastrointestinal Oncology.Surgical resection for peritoneal metastases from colorectal cancer(CRC)has been gradually accepted in t... In this editorial we examine the article by Wu et al published in the World Journal of Gastrointestinal Oncology.Surgical resection for peritoneal metastases from colorectal cancer(CRC)has been gradually accepted in the medical oncology community.A randomized trial(PRODIGE 7)on cytoreductive surgery(CRS)with hyperthermic intraperitoneal chemotherapy(HIPEC)failed to prove any benefit of oxaliplatin in the overall survival of patients with peritoneal metastases from colorectal origin.Nevertheless,isolated systemic chemotherapy for CRC stage IV has demonstrated a reduced response in peritoneal metastases than that obtained in other metastatic sites such as the liver.Another tool is required in those patients to achieve more local control of the disease.Surgical groups in peritoneal surgery continue to use HIPEC in their procedures,using other agents than oxaliplatin for peritoneal cavity infusion,such as mitomycin C.These patients present with complex surgical issues to manage,and consequently a large burden of complications has to be anticipated.Therefore,identifying patients who will benefit from CRS with or without HIPEC would be of great interest. 展开更多
关键词 Colorectal cancer Peritoneal metastasis Hyperthermic intraoperative chemotherapy treatment strategies Peritoneal Surface Oncology GroupInternational
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Advancing treatment strategies:Insights from network meta-analysis of hepatic arterial infusion chemotherapy for advanced hepatocellular carcinoma
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作者 Chun-Han Cheng Wen-Rui Hao Tzu-Hurng Cheng 《World Journal of Gastrointestinal Oncology》 SCIE 2025年第1期252-255,共4页
This study examines the pivotal findings of the network meta-analysis of Zhou et al,which evaluated the efficacy of hepatic arterial infusion chemotherapy and combination therapies for advanced hepatocellular carcinom... This study examines the pivotal findings of the network meta-analysis of Zhou et al,which evaluated the efficacy of hepatic arterial infusion chemotherapy and combination therapies for advanced hepatocellular carcinoma(HCC).This meta-analysis suggests that therapeutic combinations have greater efficacy than do standard treatments.The article highlights the key insights that have the potential to shift current clinical practice and enhance outcomes for patients with advanced HCC.Additionally,this article discusses further research that can be conducted to optimize these treatments and achieve personalized care for patients with HCC. 展开更多
关键词 Hepatic arterial infusion chemotherapy Advanced hepatocellular carcinoma Combination therapy Network meta-analysis treatment efficacy
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Efficacy,safety and treatment satisfaction of transition to a regimen of insulin degludec/aspart:A pilot study
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作者 Na Yang Lu Lv +8 位作者 Shu-Meng Han Li-Yun He Zi-Yi Li Yu-Cheng Yang Fan Ping Ling-Ling Xu Wei Li Hua-Bing Zhang Yu-Xiu Li 《World Journal of Diabetes》 SCIE 2025年第1期65-73,共9页
BACKGROUND There is a lack of clinical evidence on the efficacy and safety of transitioning from a thrice-daily pre-mixed insulin or basal-prandial regimen to insulin degludec/aspart(IDegAsp)therapy,with insufficient ... BACKGROUND There is a lack of clinical evidence on the efficacy and safety of transitioning from a thrice-daily pre-mixed insulin or basal-prandial regimen to insulin degludec/aspart(IDegAsp)therapy,with insufficient data from the Chinese population.AIM To demonstrate the efficacy,safety,and treatment satisfaction associated with the transition to IDegAsp in type 2 diabetes mellitus(T2DM).METHODS In this 12-week open-label,non-randomized,single-center,pilot study,patients with T2DM receiving thrice-daily insulin or intensive insulin treatment were transitioned to twice-daily injections of insulin IDegAsp.Insulin doses,hemoglobin A1c(HbA1c)levels,fasting blood glucose(FBG),hypoglycemic events,a Diabetes Treatment Satisfaction Questionnaire,and other parameters were assessed at baseline and 12-weeks.RESULTS This study included 21 participants.A marked enhancement was observed in the FBG level(P=0.02),daily total insulin dose(P=0.03),and overall diabetes treatment satisfaction(P<0.01)in the participants who switched to IDegAsp.There was a decrease in HbA1c levels(7.6±1.1 vs 7.4±0.9,P=0.31)and the frequency of hypoglycemic events of those who switched to IDegAsp decreased,however,there was no statistically significant difference.CONCLUSION The present findings suggest that treatment with IDegAsp enhances clinical outcomes,particularly FBG levels,daily cumulative insulin dose,and overall satisfaction with diabetes treatment. 展开更多
关键词 Insulin degludec/aspart Type 2 diabetes management Basal-bolus insulin therapy Pre-mixed insulin Diabetes treatment satisfaction questionnaire
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The emerging role of mesenchymal stem cell-derived extracellular vesicles to ameliorate hippocampal NLRP3 inflammation induced by binge-like ethanol treatment in adolescence
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作者 Susana Mellado María JoséMorillo-Bargues +4 位作者 Carla Perpiñá-Clérigues Francisco García-García Victoria Moreno-Manzano Consuelo Guerri María Pascual 《Neural Regeneration Research》 SCIE CAS 2025年第4期1153-1163,共11页
Our previous studies have reported that activation of the NLRP3(NOD-,LRR-and pyrin domain-containing protein 3)-inflammasome complex in ethanol-treated astrocytes and chronic alcohol-fed mice could be associated with ... Our previous studies have reported that activation of the NLRP3(NOD-,LRR-and pyrin domain-containing protein 3)-inflammasome complex in ethanol-treated astrocytes and chronic alcohol-fed mice could be associated with neuroinflammation and brain damage.Mesenchymal stem cell-derived extracellular vesicles(MSC-EVs)have been shown to restore the neuroinflammatory response,along with myelin and synaptic structural alterations in the prefrontal cortex,and alleviate cognitive and memory dysfunctions induced by binge-like ethanol treatment in adolescent mice.Considering the therapeutic role of the molecules contained in mesenchymal stem cell-derived extracellular vesicles,the present study analyzed whether the administration of mesenchymal stem cell-derived extracellular vesicles isolated from adipose tissue,which inhibited the activation of the NLRP3 inflammasome,was capable of reducing hippocampal neuroinflammation in adolescent mice treated with binge drinking.We demonstrated that the administration of mesenchymal stem cell-derived extracellular vesicles ameliorated the activation of the hippocampal NLRP3 inflammasome complex and other NLRs inflammasomes(e.g.,pyrin domain-containing 1,caspase recruitment domain-containing 4,and absent in melanoma 2,as well as the alterations in inflammatory genes(interleukin-1β,interleukin-18,inducible nitric oxide synthase,nuclear factor-kappa B,monocyte chemoattractant protein-1,and C–X3–C motif chemokine ligand 1)and miRNAs(miR-21a-5p,miR-146a-5p,and miR-141-5p)induced by binge-like ethanol treatment in adolescent mice.Bioinformatic analysis further revealed the involvement of miR-21a-5p and miR-146a-5p with inflammatory target genes and NOD-like receptor signaling pathways.Taken together,these findings provide novel evidence of the therapeutic potential of MSC-derived EVs to ameliorate the hippocampal neuroinflammatory response associated with NLRP3 inflammasome activation induced by binge drinking in adolescence. 展开更多
关键词 ADOLESCENCE binge-like ethanol treatment extracellular vesicles hippocampus mesenchymal stem cells neuroinflammation NOD- LRR-and pyrin domain-containing protein 3(NLRP3)
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Scalable Ir‑Doped NiFe_(2)O_(4)/TiO_(2)Heterojunction Anode for Decentralized Saline Wastewater Treatment and H_(2)Production
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作者 Sukhwa Hong Jiseon Kim +3 位作者 Jaebeom Park Sunmi Im Michael R.Hoffmann Kangwoo Cho 《Nano-Micro Letters》 SCIE EI CAS 2025年第3期1-18,共18页
Wastewater electrolysis cells(WECs)for decentralized wastewater treatment/reuse coupled with H_(2)production can reduce the carbon footprint associated with transportation of water,waste,and energy carrier.This study ... Wastewater electrolysis cells(WECs)for decentralized wastewater treatment/reuse coupled with H_(2)production can reduce the carbon footprint associated with transportation of water,waste,and energy carrier.This study reports Ir-doped NiFe_(2)O_(4)(NFI,~5 at%Ir)spinel layer with TiO_(2)overlayer(NFI/TiO_(2)),as a scalable heterojunction anode for direct electrolysis of wastewater with circumneutral pH in a single-compartment cell.In dilute(0.1 M)NaCl solutions,the NFI/TiO_(2)marks superior activity and selectivity for chlorine evolution reaction,outperforming the benchmark IrO_(2).Robust operation in near-neutral pH was confirmed.Electroanalyses including operando X-ray absorption spectroscopy unveiled crucial roles of TiO_(2) which serves both as the primary site for Cl−chemisorption and a protective layer for NFI as an ohmic contact.Galvanostatic electrolysis of NH4+-laden synthetic wastewater demonstrated that NFI/TiO_(2)not only achieves quasi-stoichiometric NH_(4)^(+)-to-N_(2)conversion,but also enhances H_(2)generation efficiency with minimal competing reactions such as reduction of dissolved oxygen and reactive chlorine.The scaled-up WEC with NFI/TiO_(2)was demonstrated for electrolysis of toilet wastewater. 展开更多
关键词 Wastewater electrolysis cell Ir-doped NiFe_(2)O_(4) Reactive chlorine species Decentralized H_(2)production On-site wastewater treatment
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Variations in quantifying patient reported outcome measures to estimate treatment effect
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作者 Sathish Muthu Srujun Vadranapu 《World Journal of Methodology》 2025年第2期44-53,共10页
In the practice of healthcare,patient-reported outcomes(PROs)and PRO measures(PROMs)are used as an attempt to observe the changes in complex clinical situations.They guide us in making decisions based on the evidence ... In the practice of healthcare,patient-reported outcomes(PROs)and PRO measures(PROMs)are used as an attempt to observe the changes in complex clinical situations.They guide us in making decisions based on the evidence regarding patient care by recording the change in outcomes for a particular treatment to a given condition and finally to understand whether a patient will benefit from a particular treatment and to quantify the treatment effect.For any PROM to be usable in health care,we need it to be reliable,encapsulating the points of interest with the potential to detect any real change.Using structured outcome measures routinely in clinical practice helps the physician to understand the functional limitation of a patient that would otherwise not be clear in an office interview,and this allows the physician and patient to have a meaningful conver-sation as well as a customized plan for each patient.Having mentioned the rationale and the benefits of PROMs,understanding the quantification process is crucial before embarking on management decisions.A better interpretation of change needs to identify the treatment effect based on clinical relevance for a given condition.There are a multiple set of measurement indices to serve this effect and most of them are used interchangeably without clear demarcation on their differences.This article details the various quantification metrics used to evaluate the treatment effect using PROMs,their limitations and the scope of usage and implementation in clinical practice. 展开更多
关键词 Patient-reported outcome measures treatment effect Minimal clinical important difference Patient-accepted symptom state Minimum detectable change ORTHOPEDICS
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Coupling Ensemble Kalman Filter with Four-dimensional Variational Data Assimilation 被引量:26
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作者 Fuqing ZHANG Meng ZHANG James A. HANSEN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2009年第1期1-8,共8页
This study examines the performance of coupling the deterministic four-dimensional variational assimilation system (4DVAR) with an ensemble Kalman filter (EnKF) to produce a superior hybrid approach for data assim... This study examines the performance of coupling the deterministic four-dimensional variational assimilation system (4DVAR) with an ensemble Kalman filter (EnKF) to produce a superior hybrid approach for data assimilation. The coupled assimilation scheme (E4DVAR) benefits from using the state-dependent uncertainty provided by EnKF while taking advantage of 4DVAR in preventing filter divergence: the 4DVAR analysis produces posterior maximum likelihood solutions through minimization of a cost function about which the ensemble perturbations are transformed, and the resulting ensemble analysis can be propagated forward both for the next assimilation cycle and as a basis for ensemble forecasting. The feasibility and effectiveness of this coupled approach are demonstrated in an idealized model with simulated observations. It is found that the E4DVAR is capable of outperforming both 4DVAR and the EnKF under both perfect- and imperfect-model scenarios. The performance of the coupled scheme is also less sensitive to either the ensemble size or the assimilation window length than those for standard EnKF or 4DVAR implementations. 展开更多
关键词 data assimilation four-dimensional variational data assimilation ensemble Kalman filter Lorenz model hybrid method
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Testing a Four-Dimensional Variational Data Assimilation Method Using an Improved Intermediate Coupled Model for ENSO Analysis and Prediction 被引量:12
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作者 Chuan GAO Xinrong WU Rong-Hua ZHANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2016年第7期875-888,共14页
A four-dimensional variational (4D-Var) data assimilation method is implemented in an improved intermediate coupled model (ICM) of the tropical Pacific. A twin experiment is designed to evaluate the impact of the ... A four-dimensional variational (4D-Var) data assimilation method is implemented in an improved intermediate coupled model (ICM) of the tropical Pacific. A twin experiment is designed to evaluate the impact of the 4D-Var data assimilation algorithm on ENSO analysis and prediction based on the ICM. The model error is assumed to arise only from the parameter uncertainty. The "observation" of the SST anomaly, which is sampled from a "truth" model simulation that takes default parameter values and has Gaussian noise added, is directly assimilated into the assimilation model with its parameters set erroneously. Results show that 4D-Var effectively reduces the error of ENSO analysis and therefore improves the prediction skill of ENSO events compared with the non-assimilation case. These results provide a promising way for the ICM to achieve better real-time ENSO prediction. 展开更多
关键词 four-dimensional variational data assimilation intermediate coupled model twin experiment ENSO prediction
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Four-Dimensional Variational Data Assimilation Experiments for a Heavy Rain Case During the 2002 IOP in China 被引量:5
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作者 张林 倪允琪 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2005年第2期300-312,共13页
A heavy rainfall event along the mei-yu front during 22-23 June 2002 was chosen for this study. To assess the impact of the routine and additional IOP (intensive observation period) radiosonde observations on the meso... A heavy rainfall event along the mei-yu front during 22-23 June 2002 was chosen for this study. To assess the impact of the routine and additional IOP (intensive observation period) radiosonde observations on the mesoscale heavy rainfall forecast, a series of four-dimensional variational (4DVAR) data assimilation and model simulation experiments was conducted using nonhydrostatic mesoscale model MM5 and the MM5 4DVAR system. The effects of the intensive observations in the different areas on the heavy rainfall forecast were also investigated. The results showed that improvement of the forecast skill for mesoscale heavy rainfall intensity was possible from the assimilation of the IOP radiosonde observations. However, the impact of the IOP observations on the forecast of the rainfall pattern was not significant. Initial conditions obtained through the 4DVAR experiments with a 12-h assimilation window were capable of improving the 24-h forecast. The simulated results after the assimilation showed that it would be best to perform the intensive radiosonde observations in the upstream of the rainfall area and in the moisture passageway area at the same time. Initial conditions created by the 4DVAR led to the low-level moisture convergence over the rainfall area, enhanced frontogenesis and upward motion within the mei-yu front, and intensified middle- and high-level unstable stratification in front of the mei-yu front. Consequently, the heavy rainfall forecast was improved. 展开更多
关键词 intensive radiosonde observations four-dimensional variational assimilation
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Real-Time Four-Dimensional Trajectory Generation Based on Gain-Scheduling Control and a High-Fidelity Aircraft Model 被引量:3
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作者 Olusayo Obajemu Mahdi Mahfouf +3 位作者 Lohithaksha M.Maiyar Abrar Al-Hzndi Michal Weiszer Jun Chen 《Engineering》 SCIE EI 2021年第4期495-506,共12页
Aircraft ground movement plays a key role in improving airport efficiency,as it acts as a link to all other ground operations.Finding novel approaches to coordinate the movements of a fleet of aircraft at an airport i... Aircraft ground movement plays a key role in improving airport efficiency,as it acts as a link to all other ground operations.Finding novel approaches to coordinate the movements of a fleet of aircraft at an airport in order to improve system resilience to disruptions with increasing autonomy is at the center of many key studies for airport airside operations.Moreover,autonomous taxiing is envisioned as a key component in future digitalized airports.However,state-of-the-art routing and scheduling algorithms for airport ground movements do not consider high-fidelity aircraft models at both the proactive and reactive planning phases.The majority of such algorithms do not actively seek to optimize fuel efficiency and reduce harmful greenhouse gas emissions.This paper proposes a new approach for generating efficient four-dimensional trajectories(4DTs)on the basis of a high-fidelity aircraft model and gainscheduling control strategy.Working in conjunction with a routing and scheduling algorithm that determines the taxi route,waypoints,and time deadlines,the proposed approach generates fuel-efficient 4DTs in real time,while respecting operational constraints.The proposed approach can be used in two contexts:①as a reactive decision support tool to generate new trajectories that can resolve unprecedented events;and②as an autopilot system for both partial and fully autonomous taxiing.The proposed methodology is realistic and simple to implement.Moreover,simulation studies show that the proposed approach is capable of providing an up to 11%reduction in the fuel consumed during the taxiing of a large Boeing 747-100 jumbo jet. 展开更多
关键词 Aircraft model Intelligent taxiing OPTIMIZATION four-dimensional trajectory
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Four-dimensional flow magnetic resonance imaging incirrhosis 被引量:7
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作者 Zoran Stankovic 《World Journal of Gastroenterology》 SCIE CAS 2016年第1期89-102,共14页
Since its introduction in the 1970’s,magnetic resonance imaging(MRI)has become a standard imaging modality.With its broad and standardized application,it is firmly established in the clinical routine and an essential... Since its introduction in the 1970’s,magnetic resonance imaging(MRI)has become a standard imaging modality.With its broad and standardized application,it is firmly established in the clinical routine and an essential element in cardiovascular and abdominal imaging.In addition to sonography and computer tomography,MRI is a valuable tool for diagnosing cardiovascular and abdominal diseases,for determining disease severity,and for assessing therapeutic success.MRI techniques have improved over the last few decades,revealing not just morphologic information,but functional information about perfusion,diffusion and hemodynamics as well.Four-dimensional(4D)flow MRI,a time-resolved phase contrast-MRI with three-dimensional(3D)anatomic coverage and velocity encoding along all three flow directions has been used to comprehensively assess complex cardiovascular hemodynamics in multiple regions of the body.The technique enables visualization of 3D blood flow patterns and retrospective quantification of blood flow parameters in a region of interest.Over the last few years,4D flow MRI has been increasingly performed in the abdominal region.By applying different acceleration techniques,taking 4D flow MRI measurements has dropped to a reasonable scanning time of 8 to 12 min.These new developments have encouraged a growing number of patient studies in the literature validating the technique’s potential for enhanced evaluation of blood flow parameters within the liver’s complex vascular system.The purpose of this review article is to broaden our understanding of 4D flow MRI for the assessment of liver hemodynamics by providing insights into acquisition,data analysis,visualization and quantification.Furthermore,in this article we highlight its development,focussing on the clinical application of the technique. 展开更多
关键词 four-dimensional FLOW MAGNETIC resonanceimaging Phase contrast-magnetic resonance IMAGING Liver CIRRHOSIS IMAGING technique HEMODYNAMICS Bloodflow Visualization Quantification TIPS SPLANCHNIC system
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Generating one-,two-,three-and four-scroll attractors from a novel four-dimensional smooth autonomous chaotic system 被引量:3
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作者 Sara Dadras Hamid Reza Momeni 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第6期106-114,共9页
A new four-dimensional quadratic smooth autonomous chaotic system is presented in this paper, which can exhibit periodic orbit and chaos under the conditions on the system parameters. Importantly, the system can gener... A new four-dimensional quadratic smooth autonomous chaotic system is presented in this paper, which can exhibit periodic orbit and chaos under the conditions on the system parameters. Importantly, the system can generate one-, two-, three- and four-scroll chaotic attractors with appropriate choices of parameters. Interestingly, all the attractors are generated only by changing a single parameter. The dynamic analysis approach in the paper involves time series, phase portraits, Poincare maps, a bifurcation diagram, and Lyapunov exponents, to investigate some basic dynamical behaviours of the proposed four-dimensional system. 展开更多
关键词 new smooth autonomous four-dimensional chaotic system multi-scroll chaotic attractor Poincare mapping BIFURCATION Lyapunov exponent
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Bifurcations of Periodic Orbits for a Four-Dimensional System 被引量:1
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作者 刘宣亮 《Journal of Shanghai Jiaotong university(Science)》 EI 2004年第2期82-86,共5页
Consider a four-dimensional system having a two-dimensional invariant surface. By analyzing the solutions of bifurcation equations, this paper studied the bifurcation phenomena of a k multiple closed orbit in the inva... Consider a four-dimensional system having a two-dimensional invariant surface. By analyzing the solutions of bifurcation equations, this paper studied the bifurcation phenomena of a k multiple closed orbit in the invariant surface. Sufficient conditions for the existence of periodic orbits generated by the k multiple closed orbit were given. 展开更多
关键词 BIFURCATION periodic orbit four-dimensional system
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Novel four-dimensional autonomous chaotic system generating one-,two-,three- and four-wing attractors 被引量:1
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作者 余飞 王春华 +1 位作者 尹晋文 徐浩 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第11期151-158,共8页
In this paper, we propose a novel four-dimensional autonomous chaotic system. Of particular interest is that this novel system can generate one-, two, three- and four-wing chaotic attractors with the variation of a si... In this paper, we propose a novel four-dimensional autonomous chaotic system. Of particular interest is that this novel system can generate one-, two, three- and four-wing chaotic attractors with the variation of a single parameter, and the multi-wing type of the chaotic attractors can be displayed in all directions. The system is simple with a large positive Lyapunov exponent and can exhibit some interesting and complicated dynamical behaviours. Basic dynamical properties of the four-dimensional chaotic system, such as equilibrium points, the Poincare map, the bifurcation diagram and the Lyapunov exponents are investigated by using either theoretical analysis or numerical method. Finally, a circuit is designed for the implementation of the multi-wing chaotic attractors. The electronic workbench observations axe in good agreement with the numerical simulation results. 展开更多
关键词 multi-wing chaotic attractors four-dimensional chaotic system Poincare map bifurcation diagram
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Four-Dimensional Computerized Tomography (4D-CT) Reconstruction Based on the Similarity Measure of Spatial Adjacent Images 被引量:9
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作者 ZHANG Shu-xu ZHOU Ling-hong +3 位作者 CHEN Guang-jie LIN Sheng-qu YE Yu-sheng ZHANG Hai-nan 《Chinese Journal of Biomedical Engineering(English Edition)》 2008年第3期106-113,共8页
Objective:To investigate the feasibility of a 4D-CT reconstruction method based on the similarity principle of spatial adjacent images and mutual information measure. Methods:A motor driven sinusoidal motion platform ... Objective:To investigate the feasibility of a 4D-CT reconstruction method based on the similarity principle of spatial adjacent images and mutual information measure. Methods:A motor driven sinusoidal motion platform made in house was used to create one-dimensional periodical motion that was along the longitudinal axis of the CT couch. The amplitude of sinusoidal motion was set to an amplitude of ±1 cm. The period of the motion was adjustable and set to 3.5 s. Phantom objects of two eggs were placed in a Styrofoam block, which in turn were placed on the motion platform. These objects were used to simulate volumes of interest undergoing ideal periodic motion. CT data of static phantom were acquired using a multi-slice general electric (GE) LightSpeed 16-slice CT scanner in an axial mode. And the CT data of periodical motion phantom were acquired in an axial and cine-mode scan. A software program was developed by using VC++ and VTK software tools to resort the CT data and reconstruct the 4D-CT. Then all of the CT data with same phase were sorted by the program into the same series based on the similarity principle of spatial adjacent images and mutual information measure among them, and 3D reconstruction of different phase CT data were completed by using the software. Results:All of the CT data were sorted accurately into different series based on the similarity principle of spatial adjacent images and mutual information measures among them. Compared with the unsorted CT data, the motion artifacts in the 3D reconstruction of sorted CT data were reduced significantly, and all of the sorted CT series result in a 4D-CT that reflected the characteristic of the periodical motion phantom. Conclusion:Time-resolved 4D-CT reconstruction can be implemented with any general multi-slice CT scanners based on the similarity principle of spatial adjacent images and mutual information measure.The process of the 4D-CT data acquisition and reconstruction were not restricted to the hardware or software of the CT scanner and has the feasibility ,which extensive applicability. 展开更多
关键词 PHANTOM four-dimensional computed tomography (4D-CT) reconstruc-tion SIMILARITY motion artifacts mutual information
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