137 research outputs found

    A new splitting-based displacement prediction approach for location-based services

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    In location-based services (LBSs), the service is provided based on the users' locations through location determination and mobility realization. Several location prediction models have been proposed to enhance and increase the relevance of the information retrieved by users of mobile information systems, but none of them studied the relationship between accuracy rate of prediction and the performance of the model in terms of consuming resources and constraints of mobile devices. Most of the current location prediction research is focused on generalized location models, where the geographic extent is divided into regular-shape cells. These models are not suitable for certain LBSs where the objectives are to compute and present on-road services. One such technique is the Prediction Location Model (PLM), which deals with inner cell structure. The PLM technique suffers from memory usage and poor accuracy. The main goal of this paper is to propose a new path prediction technique for Location-Based Services. The new approach is competitive and more efficient compared to PLM regarding measurements such as accuracy rate of location prediction and memory usage

    Global epidemiology of vasculitis.

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    The many forms of vasculitis are characterized by inflammation of blood vessels, leading to potentially long-term sequelae including vision loss, aneurysm formation and kidney failure. Accurate estimation of the incidence and prevalence has been hampered by the absence of reliable diagnostic criteria and the rarity of these conditions; however, much progress has been made over the past two decades, although data are still lacking from many parts of the world including the Indian subcontinent, China, Africa and South America. Giant cell arteritis occurs in those aged 50 years and over and seems to mainly affect persons of northern European ancestry, whereas Takayasu arteritis occurs mainly in those aged under 40 years. By contrast, Kawasaki disease mainly occurs in children aged under 5 years and is most common in children of Asian ancestry, and IgA vasculitis occurs in children and adolescents. Although much less common than giant cell arteritis, the different forms of antineutrophil cytoplasmic antibody-associated vasculitis are being increasingly recognized in most populations and occur more frequently with increasing age. Behçet syndrome occurs most commonly along the ancient silk road between Europe and China. Much work needs to be done to better understand the influence of ethnicity, geographical location, environment and social factors on the development of vasculitis

    Rate of comorbidities in giant cell arteritis : A population-based study

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    Objective. To compare the rate of occurrence of comorbidities, including severe infections, in a population-based cohort of patients with biopsy-proven giant cell arteritis (GCA) with a reference population in Southern Sweden. Methods. The study included a population-based cohort of biopsy-proven GCA cases diagnosed between 1998 and 2010 from the Skane region in Southern Sweden (population: 1.2 million). For each patient, 4 reference subjects were identified from the general population and matched for age, sex, area of residence, and date of diagnosis of GCA. Using the Skane Healthcare Register, comorbidities and severe infections (requiring hospitalization) diagnosed after GCA onset were identified. The rate of the first occurrence of each comorbidity was the result of dividing the number of subjects with a given comorbidity by the person-years of followup. The rate ratio (RR; GCA:reference population) was also calculated. Results. There were 768 patients (571 women) with GCA and 3066 reference persons included in the study. The RR were significantly elevated for osteoporosis (2.81, 95% CI 2.33-3.37), followed by venous thromboembolic diseases (2.36, 95% CI 1.61-3.40), severe infections (1.85, 95% CI 1.57-2.18), thyroid diseases (1.55, 95% CI 1.25-1.91), cerebrovascular accidents (1.40, 95% CI 1.12-1.74), and diabetes mellitus (1.29, 95% CI 1.05-1.56). The RR for ischemic heart disease was elevated, but did not reach statistical significance (1.20, 95% CI 1.00-1.44). Conclusion. Patients with GCA have higher rates of selected comorbidities, including severe infections, compared with a reference population. Several of these comorbidities may be related to treatment with glucocorticosteroids, emphasizing the unmet need to find alternative treatments for GCA

    Simulation Study of the Variations in Driving Pressure and Frequency on Microbubbles Contras Agents Behavior

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    The difference between the density of the gas core of microbubbles and the surrounding media causes the behavior of microbubbles contrast agents in an ultrasound field to be nonlinear and intricate. In addition, many factors affect the radial oscillations of these microbubbles. Some of these factors are related with the bubble structure and its shell material such as the initial radius of the bubble, shell thickness, viscosity of the shell material and its elasticity. Other factors are related with the incident acoustic wave such as the driving frequency and driving pressure amplitude. In this simulation study the effects of pressure and frequency as influential factors on the stability of the microbubble were studied in wide range (frequencies are extend from f<fr to f≈3 fr, pressure extends from 0.05 to 1.5 MPa.), and analyzed using the bifurcation theory to visualize and characterize the effect of these factors on the microbubbles behavior. The study expounded theoretically that the generation the higher order of subharmonic oscillations is possible to result at high driving frequencies with low and appropriate driving pressures

    Impact of baseline anemia in patients with acute coronary syndromes undergoing percutaneous coronary intervention:a prespecified analysis from the VALIDATE-SWEDEHEART trial

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    Background The impact of baseline anemia in a contemporary acute coronary syndrome (ACS) population undergoing percutaneous coronary intervention in the era of predominant radial artery access, potent P2Y12 inhibition, and rare use of glycoprotein IIb/IIIa inhibitors has not been adequately studied. Methods and Results ACS patients who underwent percutaneous coronary intervention between 2014 and 2016 in the VALIDATE-SWEDEHEART (Bivalirudin Versus Heparin in ST-Segment and Non-ST-Segment Elevation Myocardial Infarction in Patients on Modern Antiplatelet Therapy in the Swedish Web System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies Registry) trial without missing values for hemoglobin were included (n=5482). Mortality, myocardial reinfarction, and major bleeding at 180 days were assessed using Cox regression models and propensity score matching. All studied comorbidities were more common in ACS patients who had anemia (n=792). ACS patients with anemia had higher rates of 180-day mortality (6.9% versus 2.1%; hazard ratio, 1.9; 95% CI, 1.3-2.7; P<0.001), myocardial reinfarction (4.3% versus 1.9%; hazard ratio, 1.7; 95% CI, 1.1-2.7; P=0.013), and major bleeding (13.4% versus 8.2%; hazard ratio, 1.3; 95% CI, 1.0-1.6; P=0.041). The results were most evident in patients with a hemoglobin value <100 g/L, who had a nearly 10 times higher mortality rate. Conclusions Baseline anemia in ACS patients undergoing percutaneous coronary intervention, treated according to current practice including routine radial artery access, constitutes a high-risk feature for both ischemic events, bleeding events, and mortality. A multidisciplinary approach is warranted to maximize benefit and minimize patient risk. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT02311231

    Efficacy and safety of rituximab in the treatment of eosinophilic granulomatosis with polyangiitis.

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    INTRODUCTION: Eosinophilic granulomatosis with polyangiitis (EGPA) is a subset of antineutrophil cytoplasmic antibodies (ANCA) associated vasculitis with distinct pathophysiological mechanisms, clinical features and treatment responses. Rituximab is a licensed therapy for granulomatosis with polyangiitis and microscopic polyangiitis but there is limited experience of rituximab in EGPA. METHODS: EGPA patients from a tertiary centre who received rituximab for mostly refractory EGPA or in whom cyclophosphamide was contra indicated were studied. A standardised dataset was collected at time of initial treatment and every 3 months for 24 months. Response was defined as a Birmingham Vasculitis Activity Score (BVAS) of 0 and partial response as ≥50% reduction in BVAS from baseline. Remission was defined as a BVAS of 0 on prednisolone dose ≤5 mg. RESULTS: Sixty-nine patients (44 female) received rituximab between 2003 and 2017. Improvement (response and partial response) was observed in 76.8% of patients at 6 months, 82.8% at 12 months and in 93.2% by 24 months, while relapses occurred in 54% by 24 months, with asthma being the most frequent manifestation. The median BVAS decreased from 6 at baseline to 1 at 6 months, and 0 at 12 and 24 months. Prednisolone dose (mg/day, median) decreased from 12.5 to 7, 7.5 and 5 at 6, 12 and 24 months, respectively. ANCA positive patients had a longer asthma/ear, nose and throat (ENT) relapse-free survival time and a shorter time to remission. DISCUSSION: Rituximab demonstrated some efficacy in EGPA and led to a reduction in prednisolone requirement, but asthma and ENT relapse rates were high despite continued treatment. The ANCA positive subset appeared to have a more sustained response on isolated asthma/ENT exacerbations

    Long-term outcomes of patients with Takayasu arteritis and renal artery involvement: a cohort study.

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    OBJECTIVE: To describe the long-term outcomes of patients with Takayasu arteritis (TAK) and renal artery involvement (RAI). METHODS: A retrospective review of 122 patients with TAK at three tertiary centres in Canada, Sweden and the UK. Data on demographics, laboratory and clinical parameters, medications and angiography findings were collected. Non-renal and renal parameters were compared at baseline and follow-up. RESULTS: A total of 37 patients (30%) with RAI were identified: 18 (49%) with unilateral and 19 (51%) with bilateral RAI. Patients were predominantly female (89%). The median age at diagnosis was 27 years [interquartile range (IQR) 16-38]. The median follow-up time was 7 years (IQR 2-12). Hypertension was seen in 27 patients (73%) at presentation and 25 (68%) at follow-up. The median estimated glomerular filtration (eGFR) at presentation was 94 and 98 ml/min/1.73 m2 in those with unilateral and bilateral RAI, respectively. The corresponding median eGFR at follow-up was 101.5 and 104 ml/min/1.73 m2, respectively. Three patients at presentation and two at follow-up had an eGFR of <60 ml/min/1.73 m2. Five underwent endovascular intervention and three required surgical interventions. Among the 33 patients with radiologic follow-up, 23 (69%) had persistent RAI and 10 (30%) had resolution of RAI. One (6%) patient with unilateral RAI developed bilateral RAI and three (19%) with bilateral RAI regressed to unilateral RAI. Over time, 23 (62%) patients had stable renal function, 7 (19%) had improvement and 4 had a decline in renal function; no patient developed end-stage renal disease (ESRD). CONCLUSION: In this series of TAK patients with RAI, long-term non-renal and renal outcomes were favourable. No patient experienced ESRD or died

    Location prediction based on a sector snapshot for location-based services

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    In location-based services (LBSs), the service is provided based on the users' locations through location determination and mobility realization. Most of the current location prediction research is focused on generalized location models, where the geographic extent is divided into regular-shaped cells. These models are not suitable for certain LBSs where the objectives are to compute and present on-road services. Such techniques are the new Markov-based mobility prediction (NMMP) and prediction location model (PLM) that deal with inner cell structure and different levels of prediction, respectively. The NMMP and PLM techniques suffer from complex computation, accuracy rate regression, and insufficient accuracy. In this paper, a novel cell splitting algorithm is proposed. Also, a new prediction technique is introduced. The cell splitting is universal so it can be applied to all types of cells. Meanwhile, this algorithm is implemented to the Micro cell in parallel with the new prediction technique. The prediction technique, compared with two classic prediction techniques and the experimental results, show the effectiveness and robustness of the new splitting algorithm and prediction technique

    Data quality and patient characteristics in European ANCA-associated vasculitis registries: data retrieval by federated querying

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    Objectives This study aims to describe the data structure and harmonisation process, explore data quality and define characteristics, treatment, and outcomes of patients across six federated antineutrophil cytoplasmic antibody-associated vasculitis (AAV) registries.Methods Through creation of the vasculitis-specific Findable, Accessible, Interoperable, Reusable, VASCulitis ontology, we harmonised the registries and enabled semantic interoperability. We assessed data quality across the domains of uniqueness, consistency, completeness and correctness. Aggregated data were retrieved using the semantic query language SPARQL Protocol and Resource Description Framework Query Language (SPARQL) and outcome rates were assessed through random effects meta-analysis.Results A total of 5282 cases of AAV were identified. Uniqueness and data-type consistency were 100% across all assessed variables. Completeness and correctness varied from 49%–100% to 60%–100%, respectively. There were 2754 (52.1%) cases classified as granulomatosis with polyangiitis (GPA), 1580 (29.9%) as microscopic polyangiitis and 937 (17.7%) as eosinophilic GPA. The pattern of organ involvement included: lung in 3281 (65.1%), ear-nose-throat in 2860 (56.7%) and kidney in 2534 (50.2%). Intravenous cyclophosphamide was used as remission induction therapy in 982 (50.7%), rituximab in 505 (17.7%) and pulsed intravenous glucocorticoid use was highly variable (11%–91%). Overall mortality and incidence rates of end-stage kidney disease were 28.8 (95% CI 19.7 to 42.2) and 24.8 (95% CI 19.7 to 31.1) per 1000 patient-years, respectively.Conclusions In the largest reported AAV cohort-study, we federated patient registries using semantic web technologies and highlighted concerns about data quality. The comparison of patient characteristics, treatment and outcomes was hampered by heterogeneous recruitment settings

    EULAR recommendations for the management of ANCA-associated vasculitis : 2022 update

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    Funding Information: The authors wish to thank the librarian Oliver Weiner (Medical Department of the Kiel University Library, Kiel, Germany) for advice and assistance during the SLR. DJ was supported by the NIHR Cambridge Biomedical Research Centre. Publisher Copyright: © Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.Background: Since the publication of the EULAR recommendations for the management of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in 2016, several randomised clinical trials have been published that have the potential to change clinical care and support the need for an update. Methods: Using EULAR standardised operating procedures, the EULAR task force undertook a systematic literature review and sought opinion from 20 experts from 16 countries. We modified existing recommendations and created new recommendations. Results: Four overarching principles and 17 recommendations were formulated. We recommend biopsies and ANCA testing to assist in establishing a diagnosis of AAV. For remission induction in life-threatening or organ-threatening AAV, we recommend a combination of high-dose glucocorticoids (GCs) in combination with either rituximab or cyclophosphamide. We recommend tapering of the GC dose to a target of 5 mg prednisolone equivalent/day within 4-5 months. Avacopan may be considered as part of a strategy to reduce exposure to GC in granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA). Plasma exchange may be considered in patients with rapidly progressive glomerulonephritis. For remission maintenance of GPA/MPA, we recommend rituximab. In patients with relapsing or refractory eosinophilic GPA, we recommend the use of mepolizumab. Azathioprine and methotrexate are alternatives to biologics for remission maintenance in AAV. Conclusions: In the light of recent advancements, these recommendations provide updated guidance on AAV management. As substantial data gaps still exist, informed decision-making between physicians and patients remains of key relevance.Peer reviewe
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