期刊文献+
共找到3,735篇文章
< 1 2 187 >
每页显示 20 50 100
Development and validation of a nomogram model for predicting the risk of pre-hospital delay in patients with acute myocardial infarction
1
作者 Jiao-Yu Cao Li-Xiang Zhang Xiao-Juan Zhou 《World Journal of Cardiology》 2024年第2期80-91,共12页
BACKGROUND Acute myocardial infarction(AMI)is a severe cardiovascular disease caused by the blockage of coronary arteries that leads to ischemic necrosis of the myocardium.Timely medical contact is critical for succes... BACKGROUND Acute myocardial infarction(AMI)is a severe cardiovascular disease caused by the blockage of coronary arteries that leads to ischemic necrosis of the myocardium.Timely medical contact is critical for successful AMI treatment,and delays increase the risk of death for patients.Pre-hospital delay time(PDT)is a significant challenge for reducing treatment times,as identifying high-risk patients with AMI remains difficult.This study aims to construct a risk prediction model to identify high-risk patients and develop targeted strategies for effective and prompt care,ultimately reducing PDT and improving treatment outcomes.AIM To construct a nomogram model for forecasting pre-hospital delay(PHD)likelihood in patients with AMI and to assess the precision of the nomogram model in predicting PHD risk.METHODS A retrospective cohort design was employed to investigate predictive factors for PHD in patients with AMI diagnosed between January 2022 and September 2022.The study included 252 patients,with 180 randomly assigned to the development group and the remaining 72 to the validation group in a 7:3 ratio.Independent risk factors influencing PHD were identified in the development group,leading to the establishment of a nomogram model for predicting PHD in patients with AMI.The model's predictive performance was evaluated using the receiver operating characteristic curve in both the development and validation groups.RESULTS Independent risk factors for PHD in patients with AMI included living alone,hyperlipidemia,age,diabetes mellitus,and digestive system diseases(P<0.05).A characteristic curve analysis indicated area under the receiver operating characteristic curve values of 0.787(95%confidence interval:0.716–0.858)and 0.770(95%confidence interval:0.660-0.879)in the development and validation groups,respectively,demonstrating the model's good discriminatory ability.The Hosmer–Lemeshow goodness-of-fit test revealed no statistically significant disparity between the anticipated and observed incidence of PHD in both development and validation cohorts(P>0.05),indicating satisfactory model calibration.CONCLUSION The nomogram model,developed with independent risk factors,accurately forecasts PHD likelihood in AMI individuals,enabling efficient identification of PHD risk in these patients. 展开更多
关键词 pre-hospital delay Acute myocardial infarction Risk prediction NOMOGRAM
下载PDF
Correlation Study of Neurotransmitter and Immune Levels in Pre-Hospital Emergency Nurses with Post-Traumatic Stress Disorder
2
作者 Yanling Zhou Min Guo +1 位作者 Xiangling Jiang Long Li 《Journal of Behavioral and Brain Science》 2024年第1期12-22,共11页
Objective: To investigate the occurrence of PTSD in pre-hospital emergency nurses and its related factors, and to compare the differences of neurotransmitter and immune-related factors between pre-hospital emergency n... Objective: To investigate the occurrence of PTSD in pre-hospital emergency nurses and its related factors, and to compare the differences of neurotransmitter and immune-related factors between pre-hospital emergency nurses who experienced traumatic events and those who did not develop PTSD and healthy people. How: Post-traumatic Stress Disorder Self-Rating Scale (PCL-C) tests were performed on pre-hospital emergency nurses in PTSD group, non-PTSD group and healthy control group, and the plasma monoamine neurotransmitters and serum cytokines were determined by double-antibody sandwich ABC-ELISA assay using enzyme-linked adsorption kit provided by Shanghai Xitang Biotechnology Co., Ltd. Results: 1) There were statistically significant differences in PCL-C scores between PTSD group, non-PTSD group and healthy group (p α between PTSD group, non-PTSD group and healthy group (p Conclusion: Pre-hospital emergency nurses should have early psychological intervention and guidance to reduce the occurrence of PTSD in emergency and emergency nurses. 展开更多
关键词 pre-hospital First Aid NURSE Post-Traumatic Stress Disorder NEUROIMMUNOLOGY
下载PDF
Parental Knowledge of Pre-Hospital Management of Avulsed Permanent Tooth in Children at Kath
3
作者 Ama Agyeibea Amuasi Samuel K. Addo Solomon Obiri-Yeboah 《Open Journal of Stomatology》 2024年第2期87-102,共16页
BACKGROUND: Permanent tooth avulsion is one of the severe forms of dental traumatic injuries. The immediate action taken at the site of the accident is crucial to the prognosis of the tooth. Replantation is considered... BACKGROUND: Permanent tooth avulsion is one of the severe forms of dental traumatic injuries. The immediate action taken at the site of the accident is crucial to the prognosis of the tooth. Replantation is considered as the treatment of choice. OBJECTIVE: The study was undertaken to assess the knowledge of parents who accompany their children to the pediatric dental clinic, KATH on the pre-hospital management of avulsed permanent tooth in children. METHODS: A researcher administered structured questionnaire was used to collect data on the knowledge of pre-hospital management of avulsed permanent tooth from 83 parents who accompanied their wards to the pediatric dental clinic at KATH. RESULTS: A total of 83 parents were involved in the study. 30 (36%) were males while 53 (64%) were females. The majority of the parents (57%) were either university trained or had attended college of education. Only 32 parents (39%) were aware of the possibility of replantation. Majority of the parents chose non-physiologic media as the transport media of choice and only 10% would attempt self-replantation before seeking professional help. 76 parents (92%) had no previous education on pre-hospital management of avulsed tooth. CONCLUSION: The results obtained from this study indicate that parental knowledge on pre-hospital management of avulsed permanent tooth is low hence the need for massive public educational campaigns. 展开更多
关键词 Parental Knowledge Tooth Avulsion pre-hospital Management Permanent Tooth
下载PDF
Analysis of the Effect of Humanistic Care in the Process of Pre-Hospital Emergency Care
4
作者 Rui Cao Zhe Chen 《Journal of Clinical and Nursing Research》 2024年第8期302-305,共4页
Objective:To explore the effectiveness of humanistic care in pre-hospital emergency care.Methods:From April 2020 to January 2021,80 pre-hospital emergency patients were studied.The patients were randomly divided into ... Objective:To explore the effectiveness of humanistic care in pre-hospital emergency care.Methods:From April 2020 to January 2021,80 pre-hospital emergency patients were studied.The patients were randomly divided into two groups:a control group(n=40),which received conventional care,and an experimental group(n=40),which received humanistic care.The effects of nursing care and psychological state were compared between the two groups.Results:The experimental group showed better nursing outcomes and a more positive psychological state compared to the control group(P<0.05).Conclusion:Humanistic care in pre-hospital emergency settings is more effective in reducing patients’anxiety and depression,enhancing the operational abilities and service attitudes of nursing staff,and increasing the emergency success rate. 展开更多
关键词 Humanistic care pre-hospital emergency care Negative emotion Effect analysis
下载PDF
Factors Influencing Pre-hospital Patient Delay in Patients with Acute Myocardial Infarction 被引量:2
5
作者 La Xie Su-Fang Huang You-Zhen Hu 《Chinese Nursing Research》 CAS 2015年第2期56-62,共7页
Acute myocardial infarction (AMI) is a dangerous disease with a high mortality rate. For AMI patients, the outcome of the patients depends on time to beginning of effective treatment in addition to other factors suc... Acute myocardial infarction (AMI) is a dangerous disease with a high mortality rate. For AMI patients, the outcome of the patients depends on time to beginning of effective treatment in addition to other factors such as severity of disease and involved vessels etc. The key is whether reperfusion therapy is started early enough after the onset of symptoms, and the benefit of reperfusion therapy depends on the time, too. The delay of AMI treatment is divided into pre-hospital delay and in-hospital delay. In-hospital delay, Door-to-Balloon Time, has been well controlled. Pre-hospital delay, accounting for 75% of the total delay time, is the most important factor affect- ing AMI treatment. Patient delay (PD) time for AMI patients is summarised in this study. 展开更多
关键词 Acute myocardial infarctionpre-hospital delay Factors
下载PDF
Factors influencing pre-hospital delay among patients with acute myocardial infarction in Iran 被引量:3
6
作者 Maryam Momeni Arsalan Salari +2 位作者 Shora Shafighnia Atefeh Ghanbari Fardin Mirbolouk 《Chinese Medical Journal》 SCIE CAS CSCD 2012年第19期3404-3409,共6页
Background Acute myocardial infarction (AMI) is the leading cause of morbidity and disability among Iranian population. Pre-hospital delay is an important cause of increasing early and also late mortality in AMI. Th... Background Acute myocardial infarction (AMI) is the leading cause of morbidity and disability among Iranian population. Pre-hospital delay is an important cause of increasing early and also late mortality in AMI. Thus the aim of the present study was to identify the factors influencing pre-hospital delay among patients with AMI in Iran. Methods Between August 2010 and May 2011, a cross-sectional and single-center survey was conducted on 162 consecutive patients with ST-elevation myocardial infarction (STEMI) admitted to Cardiac Care Unit (CCU) of Dr. Heshmat Hospital, Rasht. All patients were interviewed by the third author within 7 days after admission by using a four-part questionnaire including socio-demographic, clinical, situational and cognitive factors. Data were analyzed by descriptive and Logistic regression model at P 〈 0.05 using SPSS 16. Results Mean age was (60.11±12.29) years in all patients. Majority of patients (65.4%) were male. The median of pre-hospital delay was 2 hours, with a mean delay of 7.4 hours (±16.25 hours). Regression analysis showed that admission in weekend (P 〈0.04, 0R=1.033, 95% Cl=1.187-2.006) and misinterpretation of symptoms as cardiac origin (P 〈0.002, OR=1.986, 95% Cl=1.254-3.155) and perceiving symptoms to not be so serious (P 〈0.003, OR=3.264, 95% Cl=1.492-7.142) were factors influencing pre-hospital delay 〉 2 hours. Conclusions Our findings highlight the importance of cognitive factors on decision-making process and pre-hospital delays. Health care providers can educate the public on AMI to enable them recognize the signs and symptoms of AMI correctly and realize the benefits of early treatment. 展开更多
关键词 pre-hospital delay acute myocardial infarction cardiovascular disease
原文传递
Prescribed Performance Tracking Control of Time-Delay Nonlinear Systems With Output Constraints 被引量:1
7
作者 Jin-Xi Zhang Kai-Di Xu Qing-Guo Wang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第7期1557-1565,共9页
The problem of prescribed performance tracking control for unknown time-delay nonlinear systems subject to output constraints is dealt with in this paper. In contrast with related works, only the most fundamental requ... The problem of prescribed performance tracking control for unknown time-delay nonlinear systems subject to output constraints is dealt with in this paper. In contrast with related works, only the most fundamental requirements, i.e., boundedness and the local Lipschitz condition, are assumed for the allowable time delays. Moreover, we focus on the case where the reference is unknown beforehand, which renders the standard prescribed performance control designs under output constraints infeasible. To conquer these challenges, a novel robust prescribed performance control approach is put forward in this paper.Herein, a reverse tuning function is skillfully constructed and automatically generates a performance envelop for the tracking error. In addition, a unified performance analysis framework based on proof by contradiction and the barrier function is established to reveal the inherent robustness of the control system against the time delays. It turns out that the system output tracks the reference with a preassigned settling time and good accuracy,without constraint violations. A comparative simulation on a two-stage chemical reactor is carried out to illustrate the above theoretical findings. 展开更多
关键词 Nonlinear systems output constraints prescribed performance reference tracking time delays
下载PDF
Attosecond ionization time delays in strong-field physics
8
作者 马永哲 倪宏程 吴健 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期102-121,共20页
Electronic processes within atoms and molecules reside on the timescale of attoseconds. Recent advances in the laserbased pump-probe interrogation techniques have made possible the temporal resolution of ultrafast ele... Electronic processes within atoms and molecules reside on the timescale of attoseconds. Recent advances in the laserbased pump-probe interrogation techniques have made possible the temporal resolution of ultrafast electronic processes on the attosecond timescale, including photoionization and tunneling ionization. These interrogation techniques include the attosecond streak camera, the reconstruction of attosecond beating by interference of two-photon transitions, and the attoclock. While the former two are usually employed to study photoionization processes, the latter is typically used to investigate tunneling ionization. In this review, we briefly overview these timing techniques towards an attosecond temporal resolution of ionization processes in atoms and molecules under intense laser fields. In particular, we review the backpropagation method, which is a novel hybrid quantum-classical approach towards the full characterization of tunneling ionization dynamics. Continued advances in the interrogation techniques promise to pave the pathway towards the exploration of ever faster dynamical processes on an ever shorter timescale. 展开更多
关键词 strong-field ionization ATTOSECOND time delay photoionization time delay tunneling time delay attosecond streak camera reconstruction of attosecond beating by interference of two-photon transitions(RABBITT) attoclock backpropagation
下载PDF
Examining the association between delay discounting,delay aversion and physical activity in Chinese adults with type-2 diabetes mellitus
9
作者 Yong-Dong An Guo-Xia Ma +3 位作者 Xing-Kui Cai Ying Yang Fang Wang Zhan-Lin Zhang 《World Journal of Diabetes》 SCIE 2024年第4期675-685,共11页
BACKGROUND The role of physical activity in diabetes is critical,influencing this disease's development,man-agement,and overall outcomes.In China,22.3%of adults do not meet the minimum level of physical activity r... BACKGROUND The role of physical activity in diabetes is critical,influencing this disease's development,man-agement,and overall outcomes.In China,22.3%of adults do not meet the minimum level of physical activity recommended by the World Health Organization.Therefore,it is imperative to identify the factors that contributing to lack of physical activity must be identified.AIM To investigate the relationship among delay discounting,delay aversion,glycated hemoglobin(HbA1c),and various levels of physical activity in Chinese adults diagnosed with type 2 diabetes mellitus(T2DM).METHODS In 2023,400 adults with T2DM were recruited from the People's Hospital of Linxia Hui Autonomous Prefecture of Gansu Province.A face-to-face questionnaire was used to gather demographic data and details on physical activity,delay discounting,and delay aversion.In addition,HbA1c levels were measured in all 400 participants.The primary independent variables considered were delay discounting and delay aversion.The outcome variables included HbA1c levels and different intensity levels of physical activity,including walking,moderate physical activity,and vigorous physical activity.Multiple linear regression models were utilized to assess the relationship between delay discounting,delay aversion,and HbA1c levels,along with the intensity of different physical activity measured in met-hours per week.RESULTS After controlling for the sample characteristics,delay discounting was negatively associated with moderate physical activity(β=-2.386,95%CI:-4.370 to-0.401).Meanwhile,delay aversion was negatively associated with the level of moderate physical activity(β=-3.527,95%CI:-5.578 to-1.476)in the multiple linear regression model,with statistically significant differences.CONCLUSION Elevated delay discounting and increased delay aversion correlated with reduced levels of moderate physical activity.Result suggests that delay discounting and aversion may influence engagement in moderate physical activity.This study recommends that health administration and government consider delay discounting and delay aversion when formulating behavioral intervention strategies and treatment guidelines involving physical activity for patients with T2DM,which may increase participation in physical activity.This study contributes a novel perspective to the research on physical activity in adults with T2DM by examining the significance of future health considerations and the role of emotional responses to delays. 展开更多
关键词 Type 2 diabetes mellitus delay discounting delay aversion Physical activity
下载PDF
Spectrum of delayed post-hypoxic leukoencephalopathy syndrome:A systematic review
10
作者 Bahadar S Srichawla Maria A Garcia-Dominguez 《World Journal of Clinical Cases》 SCIE 2024年第29期6285-6301,共17页
BACKGROUND Delayed post hypoxic leukoencephalopathy syndrome(DPHLS),also known as Grinker’s myelinopathy,is a rare but significant neurological condition that manifests days to weeks after a hypoxic event.Characteriz... BACKGROUND Delayed post hypoxic leukoencephalopathy syndrome(DPHLS),also known as Grinker’s myelinopathy,is a rare but significant neurological condition that manifests days to weeks after a hypoxic event.Characterized by delayed onset of neurological and cognitive deficits,DPHLS presents substantial diagnostic and therapeutic challenges.AIM To consolidate current knowledge on pathophysiology,clinical features,diagnostic approaches,and management strategies for DPHLS,providing a comprehensive overview and highlighting gaps for future research.METHODS Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes guidelines,we systematically searched PubMed,ScienceDirect and Hinari databases using terms related to delayed post-hypoxic leukoencephalopathy.Inclusion criteria were original research articles,case reports,and case series involving human subjects with detailed clinical,neuroimaging,or pathological data on DPHLS.Data were extracted on study characteristics,participant demographics,clinical features,neuroimaging findings,pathological findings,treatment,and outcomes.The quality assessment was performed using the Joanna Briggs Institute critical appraisal checklist.RESULTS A total of 73 cases were reviewed.Common comorbidities included schizoaffective disorder,bipolar disorder,hypertension,and substance use disorder.The primary causes of hypoxia were benzodiazepine overdose,opioid overdose,polysubstance overdose,and carbon monoxide(CO)poisoning.Symptoms frequently include decreased level of consciousness,psychomotor agitation,cognitive decline,parkinsonism,and encephalopathy.Neuroimaging commonly revealed diffuse T2 hyperintensities in cerebral white matter,sometimes involving the basal ganglia and the globus pallidus.Magnetic resonance spectroscopy often showed decreased N-acetylaspartate,elevated choline,choline-to-creatinine ratio,and normal or elevated lactate.Treatment is often supportive,including amantadine,an antioxidant cocktail,and steroids.Hyperbaric oxygen therapy may be beneficial in those with CO poisoning.Parkinsonism was often treated with levodopa.Most of the patients had substantial recovery over the course of months and many cases had some residual neurocognitive deficits.CONCLUSION DPHLS remains a complex and multifaceted condition with various etiologies and clinical manifestations.Early recognition and appropriate management are crucial to improving patient outcomes.Future research should focus on standardizing diagnostic criteria,using advanced imaging techniques,and exploring therapeutic interventions to improve understanding and treatment of DPHLS.Conducting prospective cohort studies and developing biomarkers for early diagnosis and monitoring will be essential to advance patient care. 展开更多
关键词 delayed post hypoxic leukoencephalopathy syndrome Anoxic encephalopathy delayed post hypoxic leukoencephalopathy Hypoxic-ischemic brain injury Grinker's myelinopathy Toxic leukoencephalopathy Toxic leukoencephalopathy delayed postanoxic encephalopathy Carbon monoxide poisoning
下载PDF
Analysis and Design of Time-Delay Impulsive Systems Subject to Actuator Saturation
11
作者 Chenhong Zhu Xiuping Han Xiaodi Li 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第1期196-204,共9页
This paper investigates the exponential stability and performance analysis of nonlinear time-delay impulsive systems subject to actuator saturation. When continuous dynamics is unstable, under some conditions, it is s... This paper investigates the exponential stability and performance analysis of nonlinear time-delay impulsive systems subject to actuator saturation. When continuous dynamics is unstable, under some conditions, it is shown that the system can be stabilized by a class of saturated delayed-impulses regardless of the length of input delays. Conversely, when the system is originally stable, it is shown that under some conditions, the system is robust with respect to sufficient small delayed-impulses. Moreover, the design problem of the controller with the goal of obtaining a maximized estimate of the domain of attraction is formulated via a convex optimization problem. Three examples are provided to demonstrate the validity of the main results. 展开更多
关键词 delayed impulses impulsive control impulsive disturbance nonlinear systems SATURATION
下载PDF
A nonlocal dispersal and time delayed HIV infection model with general incidences
12
作者 WU Peng ZHANG Yu-huai WANG Ling 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2024年第3期448-457,共10页
Biologically,because of the impact of reproduction period and nonlocal dispersal of HIV-infected cells,time delay and spatial heterogeneity should be considered.In this paper,we establish an HIV infection model with n... Biologically,because of the impact of reproduction period and nonlocal dispersal of HIV-infected cells,time delay and spatial heterogeneity should be considered.In this paper,we establish an HIV infection model with nonlocal dispersal and infection age.Moreover,applying the theory of Fourier transformation and von Foerster rule,we transform the model to an integrodifferential equation with nonlocal time delay and dispersal.The well-posedness,positivity,and boundedness of the solution for the model are studied. 展开更多
关键词 HIV model nonlocal dispersal time delay general incidences
下载PDF
Surgical techniques to prevent delayed gastric emptying after pancreaticoduodenectomy
13
作者 Peng Duan Lu Sun +2 位作者 Kai Kou Xin-Rui Li Ping Zhang 《Hepatobiliary & Pancreatic Diseases International》 SCIE CAS CSCD 2024年第5期449-457,共9页
Background: Delayed gastric emptying(DGE) is one of the most common complications after pancreaticoduodenectomy(PD). DGE represents impaired gastric motility without significant mechanical obstruction and is associate... Background: Delayed gastric emptying(DGE) is one of the most common complications after pancreaticoduodenectomy(PD). DGE represents impaired gastric motility without significant mechanical obstruction and is associated with an increased length of hospital stay, increased healthcare costs, and a high readmission rate. We reviewed published studies on various technical modifications to reduce the incidence of DGE. Data sources: Studies were identified by searching Pub Med for relevant articles published up to December 2022. The following search terms were used: “pancreaticoduodenectomy”, “pancreaticojejunostomy”, “pancreaticogastrostomy”, “gastric emptying”, “gastroparesis” and “postoperative complications”. The search was limited to English publications. Additional articles were identified by a manual search of references from key articles. Results: In recent years, various surgical procedures and techniques have been explored to reduce the incidence of DGE. Pyloric resection, Billroth II reconstruction, Braun's enteroenterostomy, and antecolic reconstruction may be associated with a decreased incidence of DGE, but more high-powered studies are needed in the future. Neither laparoscopic nor robotic surgery has demonstrated superiority in preventing DGE, and the use of staplers is controversial regarding whether they can reduce the incidence of DGE. Conclusions: Despite many innovations in surgical techniques, there is no surgical procedure that is superior to others to reduce DGE. Further larger prospective randomized studies are needed. 展开更多
关键词 PANCREATICODUODENECTOMY delayed gastric emptying Postoperative complications Surgical techniques
下载PDF
Designing Proportional-Integral Consensus Protocols for Second-Order Multi-Agent Systems Using Delayed and Memorized State Information
14
作者 Honghai Wang Qing-Long Han 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第4期878-892,共15页
This paper is concerned with consensus of a secondorder linear time-invariant multi-agent system in the situation that there exists a communication delay among the agents in the network.A proportional-integral consens... This paper is concerned with consensus of a secondorder linear time-invariant multi-agent system in the situation that there exists a communication delay among the agents in the network.A proportional-integral consensus protocol is designed by using delayed and memorized state information.Under the proportional-integral consensus protocol,the consensus problem of the multi-agent system is transformed into the problem of asymptotic stability of the corresponding linear time-invariant time-delay system.Note that the location of the eigenvalues of the corresponding characteristic function of the linear time-invariant time-delay system not only determines the stability of the system,but also plays a critical role in the dynamic performance of the system.In this paper,based on recent results on the distribution of roots of quasi-polynomials,several necessary conditions for Hurwitz stability for a class of quasi-polynomials are first derived.Then allowable regions of consensus protocol parameters are estimated.Some necessary and sufficient conditions for determining effective protocol parameters are provided.The designed protocol can achieve consensus and improve the dynamic performance of the second-order multi-agent system.Moreover,the effects of delays on consensus of systems of harmonic oscillators/double integrators under proportional-integral consensus protocols are investigated.Furthermore,some results on proportional-integral consensus are derived for a class of high-order linear time-invariant multi-agent systems. 展开更多
关键词 Consensus protocol Hurwitz stability multi-agent systems quasi-polynomials time delay
下载PDF
Assessment of the three representative empirical models for zenith tropospheric delay(ZTD)using the CMONOC data
15
作者 Debao Yuan Jian Li +4 位作者 Yifan Yao Fei Yang Yingying Wang Ran Chen Tairan Xu 《Geodesy and Geodynamics》 EI CSCD 2024年第5期488-494,共7页
The precise correction of atmospheric zenith tropospheric delay(ZTD)is significant for the Global Navigation Satellite System(GNSS)performance regarding positioning accuracy and convergence time.In the past decades,ma... The precise correction of atmospheric zenith tropospheric delay(ZTD)is significant for the Global Navigation Satellite System(GNSS)performance regarding positioning accuracy and convergence time.In the past decades,many empirical ZTD models based on whether the gridded or scattered ZTD products have been proposed and widely used in the GNSS positioning applications.But there is no comprehensive evaluation of these models for the whole China region,which features complicated topography and climate.In this study,we completely assess the typical empirical models,the IGGtropSH model(gridded,non-meteorology),the SHAtropE model(scattered,non-meteorology),and the GPT3 model(gridded,meteorology)using the Crustal Movement Observation Network of China(CMONOC)network.In general,the results show that the three models share consistent performance with RMSE/bias of 37.45/1.63,37.13/2.20,and 38.27/1.34 mm for the GPT3,SHAtropE and IGGtropSH model,respectively.However,the models had a distinct performance regarding geographical distribution,elevation,seasonal variations,and daily variation.In the southeastern region of China,RMSE values are around 50 mm,which are much higher than that in the western region,approximately 20 mm.The SHAtropE model exhibits better performance for areas with large variations in elevation.The GPT3 model and the IGGtropSH model are more stable across different months,and the SHAtropE model based on the GNSS data exhibits superior performance across various UTC epochs. 展开更多
关键词 GNSS Zenith tropospheric delay Empirical ZTD model CMONOC data
下载PDF
Numerical Analysis of Bacterial Meningitis Stochastic Delayed Epidemic Model through Computational Methods
16
作者 Umar Shafique Mohamed Mahyoub Al-Shamiri +3 位作者 Ali Raza Emad Fadhal Muhammad Rafiq Nauman Ahmed 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第10期311-329,共19页
Based on theWorld Health Organization(WHO),Meningitis is a severe infection of the meninges,the membranes covering the brain and spinal cord.It is a devastating disease and remains a significant public health challeng... Based on theWorld Health Organization(WHO),Meningitis is a severe infection of the meninges,the membranes covering the brain and spinal cord.It is a devastating disease and remains a significant public health challenge.This study investigates a bacterial meningitis model through deterministic and stochastic versions.Four-compartment population dynamics explain the concept,particularly the susceptible population,carrier,infected,and recovered.The model predicts the nonnegative equilibrium points and reproduction number,i.e.,the Meningitis-Free Equilibrium(MFE),and Meningitis-Existing Equilibrium(MEE).For the stochastic version of the existing deterministicmodel,the twomethodologies studied are transition probabilities and non-parametric perturbations.Also,positivity,boundedness,extinction,and disease persistence are studiedrigorouslywiththe helpofwell-known theorems.Standard and nonstandard techniques such as EulerMaruyama,stochastic Euler,stochastic Runge Kutta,and stochastic nonstandard finite difference in the sense of delay have been presented for computational analysis of the stochastic model.Unfortunately,standard methods fail to restore the biological properties of the model,so the stochastic nonstandard finite difference approximation is offered as an efficient,low-cost,and independent of time step size.In addition,the convergence,local,and global stability around the equilibria of the nonstandard computational method is studied by assuming the perturbation effect is zero.The simulations and comparison of the methods are presented to support the theoretical results and for the best visualization of results. 展开更多
关键词 BacterialMeningitis disease stochastic delayed model stability analysis extinction and persistence computational methods
下载PDF
Diagnostic delay in inflammatory bowel diseases in a German population
17
作者 Elisabeth Blüthner Annalena Dehe +11 位作者 Carsten Büning Britta Siegmund Matthias Prager Jochen Maul Alexander Krannich Jan Preiß Bertram Wiedenmann Florian Rieder Raneem Khedraki Frank Tacke Andreas Sturm Anja Schirbel 《World Journal of Gastroenterology》 SCIE CAS 2024年第29期3465-3478,共14页
BACKGROUND Early diagnosis is key to prevent bowel damage in inflammatory bowel disease(IBD).Risk factor analyses linked with delayed diagnosis in European IBD patients are scarce and no data in German IBD patients ex... BACKGROUND Early diagnosis is key to prevent bowel damage in inflammatory bowel disease(IBD).Risk factor analyses linked with delayed diagnosis in European IBD patients are scarce and no data in German IBD patients exists.AIM To identify risk factors leading to prolonged diagnostic time in a German IBD cohort.METHODS Between 2012 and 2022,430 IBD patients from four Berlin hospitals were enrolled in a prospective study and asked to complete a 16-item questionnaire to determine features of the path leading to IBD diagnosis.Total diagnostic time was defined as the time from symptom onset to consulting a physician(patient waiting time)and from first consultation to IBD diagnosis(physician diagnostic time).Univariate and multivariate analyses were performed to identify risk factors for each time period.RESULTS The total diagnostic time was significantly longer in Crohn’s disease(CD)compared to ulcerative colitis(UC)patients(12.0 vs 4.0 mo;P<0.001),mainly due to increased physician diagnostic time(5.5 vs 1.0 mo;P<0.001).In a multivariate analysis,the predominant symptoms diarrhea(P=0.012)and skin lesions(P=0.028)as well as performed gastroscopy(P=0.042)were associated with longer physician diagnostic time in CD patients.In UC,fever was correlated(P=0.020)with shorter physician diagnostic time,while fatigue(P=0.011)and positive family history(P=0.046)were correlated with longer physician diagnostic time.CONCLUSION We demonstrated that CD patients compared to UC are at risk of long diagnostic delay.Future efforts should focus on shortening the diagnostic delay for a better outcome in these patients. 展开更多
关键词 Diagnostic time Diagnostic delay Crohn’s disease Ulcerative colitis GERMANY
下载PDF
Relaxed Stability Criteria for Time-Delay Systems:A Novel Quadratic Function Convex Approximation Approach
18
作者 Shenquan Wang Wenchengyu Ji +2 位作者 Yulian Jiang Yanzheng Zhu Jian Sun 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第4期996-1006,共11页
This paper develops a quadratic function convex approximation approach to deal with the negative definite problem of the quadratic function induced by stability analysis of linear systems with time-varying delays.By i... This paper develops a quadratic function convex approximation approach to deal with the negative definite problem of the quadratic function induced by stability analysis of linear systems with time-varying delays.By introducing two adjustable parameters and two free variables,a novel convex function greater than or equal to the quadratic function is constructed,regardless of the sign of the coefficient in the quadratic term.The developed lemma can also be degenerated into the existing quadratic function negative-determination(QFND)lemma and relaxed QFND lemma respectively,by setting two adjustable parameters and two free variables as some particular values.Moreover,for a linear system with time-varying delays,a relaxed stability criterion is established via our developed lemma,together with the quivalent reciprocal combination technique and the Bessel-Legendre inequality.As a result,the conservatism can be reduced via the proposed approach in the context of constructing Lyapunov-Krasovskii functionals for the stability analysis of linear time-varying delay systems.Finally,the superiority of our results is illustrated through three numerical examples. 展开更多
关键词 Equivalent reciprocal combination technique quadratic function convex approximation approach STABILITY timevarying delay
下载PDF
A NOTE ON THE GENERAL STABILIZATION OF DISCRETE FEEDBACK CONTROL FOR NON-AUTONOMOUS HYBRID NEUTRAL STOCHASTIC SYSTEMS WITH A DELAY
19
作者 冯立超 张春艳 +1 位作者 曹进德 武志辉 《Acta Mathematica Scientia》 SCIE CSCD 2024年第3期1145-1164,共20页
Discrete feedback control was designed to stabilize an unstable hybrid neutral stochastic differential delay system(HNSDDS) under a highly nonlinear constraint in the H_∞ and exponential forms.Nevertheless,the existi... Discrete feedback control was designed to stabilize an unstable hybrid neutral stochastic differential delay system(HNSDDS) under a highly nonlinear constraint in the H_∞ and exponential forms.Nevertheless,the existing work just adapted to autonomous cases,and the obtained results were mainly on exponential stabilization.In comparison with autonomous cases,non-autonomous systems are of great interest and represent an important challenge.Accordingly,discrete feedback control has here been adjusted with a time factor to stabilize an unstable non-autonomous HNSDDS,in which new Lyapunov-Krasovskii functionals and some novel technologies are adopted.It should be noted,in particular,that the stabilization can be achieved not only in the routine H_∞ and exponential forms,but also the polynomial form and even a general form. 展开更多
关键词 hybrid neutral stochastic differential delay system discrete feedback control general stabilization polynomial stabilization
下载PDF
THE ASYMPTOTIC BEHAVIOR AND OSCILLATION FOR A CLASS OF THIRD-ORDER NONLINEAR DELAY DYNAMIC EQUATIONS
20
作者 黄先勇 邓勋环 王其如 《Acta Mathematica Scientia》 SCIE CSCD 2024年第3期925-946,共22页
In this paper,we consider a class of third-order nonlinear delay dynamic equations.First,we establish a Kiguradze-type lemma and some useful estimates.Second,we give a sufficient and necessary condition for the existe... In this paper,we consider a class of third-order nonlinear delay dynamic equations.First,we establish a Kiguradze-type lemma and some useful estimates.Second,we give a sufficient and necessary condition for the existence of eventually positive solutions having upper bounds and tending to zero.Third,we obtain new oscillation criteria by employing the Potzsche chain rule.Then,using the generalized Riccati transformation technique and averaging method,we establish the Philos-type oscillation criteria.Surprisingly,the integral value of the Philos-type oscillation criteria,which guarantees that all unbounded solutions oscillate,is greater than θ_(4)(t_(1),T).The results of Theorem 3.5 and Remark 3.6 are novel.Finally,we offer four examples to illustrate our results. 展开更多
关键词 nonlinear delay dynamic equations NONOSCILLATION asymptotic behavior Philostype oscillation criteria generalized Riccati transformation
下载PDF
上一页 1 2 187 下一页 到第
使用帮助 返回顶部