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1.
Sensors (Basel) ; 23(4)2023 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-36850414

RESUMO

Navigation is often regarded as one of the most-exciting use cases for Augmented Reality (AR). Current AR Head-Mounted Displays (HMDs) are rather bulky and cumbersome to use and, therefore, do not offer a satisfactory user experience for the mass market yet. However, the latest-generation smartphones offer AR capabilities out of the box, with sometimes even pre-installed apps. Apple's framework ARKit is available on iOS devices, free to use for developers. Android similarly features a counterpart, ARCore. Both systems work well for small spatially confined applications, but lack global positional awareness. This is a direct result of one limitation in current mobile technology. Global Navigation Satellite Systems (GNSSs) are relatively inaccurate and often cannot work indoors due to the restriction of the signal to penetrate through solid objects, such as walls. In this paper, we present the Pedestrian Augmented Reality Navigator (PAReNt) iOS app as a solution to this problem. The app implements a data fusion technique to increase accuracy in global positioning and showcases AR navigation as one use case for the improved data. ARKit provides data about the smartphone's motion, which is fused with GNSS data and a Bluetooth indoor positioning system via a Kalman Filter (KF). Four different KFs with different underlying models have been implemented and independently evaluated to find the best filter. The evaluation measures the app's accuracy against a ground truth under controlled circumstances. Two main testing methods were introduced and applied to determine which KF works best. Depending on the evaluation method, this novel approach improved the accuracy by 57% (when GPS and AR were used) or 32% (when Bluetooth and AR were used) over the raw sensor data.

2.
Heart Surg Forum ; 17(3): E163-8, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25002394

RESUMO

BACKGROUND: Myoglobin has become established as a serum marker of myocardial injury. However, myoglobin levels can increase exponentially without any correlation to postoperative clinical ischemia symptoms. In this retrospective study, we analyzed the associated factors for a non-ischemic myoglobin release. METHODS: We performed a data analysis from 532 consecutive cardiac surgery patients (2010 to 2011, 73% males; age 65 ± 11 years). Non-ischemic myoglobin elevation was defined as CK-MB <50 U/l and/or the absence of any ischemic clinical events (eg, myocardial infarction, mesenteric vascular occlusion). RESULTS: Using a multifactorial model, predictive elements and associated factors for non-ischemic myoglobin increase were male sex, ejection fraction < 30%, BMI > 30 and transfusions. Serum myoglobin was not significantly different in patients with high muscle mass. CONCLUSIONS: A non-ischemic serum myoglobin release is rare, but could be associated in subgroups of patients. Further investigations should focus on clinical targets, for example, concomitant medications for which our study was not powered.


Assuntos
Ponte Cardiopulmonar/estatística & dados numéricos , Ponte de Artéria Coronária/estatística & dados numéricos , Isquemia Miocárdica/sangue , Miocárdio/metabolismo , Mioglobina/sangue , Idoso , Biomarcadores/sangue , Ponte Cardiopulmonar/efeitos adversos , Ponte de Artéria Coronária/efeitos adversos , Reações Falso-Positivas , Feminino , Alemanha/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/diagnóstico , Isquemia Miocárdica/etiologia , Prevalência , Reprodutibilidade dos Testes , Estudos Retrospectivos , Fatores de Risco , Sensibilidade e Especificidade
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