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  1. Article ; Online: Combining brain-computer interfaces with deep reinforcement learning for robot training: a feasibility study in a simulation environment.

    Vukelić, Mathias / Bui, Michael / Vorreuther, Anna / Lingelbach, Katharina

    Frontiers in neuroergonomics

    2023  Volume 4, Page(s) 1274730

    Abstract: Deep reinforcement learning (RL) is used as a strategy to teach robot agents how to autonomously learn complex tasks. While sparsity is a natural way to define a reward in realistic robot scenarios, it provides poor learning signals for the agent, thus ... ...

    Abstract Deep reinforcement learning (RL) is used as a strategy to teach robot agents how to autonomously learn complex tasks. While sparsity is a natural way to define a reward in realistic robot scenarios, it provides poor learning signals for the agent, thus making the design of good reward functions challenging. To overcome this challenge learning from human feedback through an implicit brain-computer interface (BCI) is used. We combined a BCI with deep RL for robot training in a 3-D physical realistic simulation environment. In a first study, we compared the feasibility of different electroencephalography (EEG) systems (wet- vs. dry-based electrodes) and its application for automatic classification of perceived errors during a robot task with different machine learning models. In a second study, we compared the performance of the BCI-based deep RL training to feedback explicitly given by participants. Our findings from the first study indicate the use of a high-quality dry-based EEG-system can provide a robust and fast method for automatically assessing robot behavior using a sophisticated convolutional neural network machine learning model. The results of our second study prove that the implicit BCI-based deep RL version in combination with the dry EEG-system can significantly accelerate the learning process in a realistic 3-D robot simulation environment. Performance of the BCI-based trained deep RL model was even comparable to that achieved by the approach with explicit human feedback. Our findings emphasize the usage of BCI-based deep RL methods as a valid alternative in those human-robot applications where no access to cognitive demanding explicit human feedback is available.
    Language English
    Publishing date 2023-11-23
    Publishing country Switzerland
    Document type Journal Article
    ISSN 2673-6195
    ISSN (online) 2673-6195
    DOI 10.3389/fnrgo.2023.1274730
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Palliative Non-Operative Management in Geriatric Hip Fracture Patients: When Would Surgeons Abstain from Surgery?

    Bui, Michael / Groothuis-Oudshoorn, Catharina G M / Witteveen, Annemieke / Hegeman, Johannes H

    Journal of clinical medicine

    2024  Volume 13, Issue 6

    Abstract: Background: ...

    Abstract Background:
    Language English
    Publishing date 2024-03-11
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2662592-1
    ISSN 2077-0383
    ISSN 2077-0383
    DOI 10.3390/jcm13061594
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Conference proceedings ; Online: Investigating Feature Set Decisions for Mental State Decoding in Virtual Reality based Learning Environments

    Lingelbach, Katharina / Diers, Daniel / Bui, Michael / Vukelic, Mathias

    2023  

    Abstract: 141 ... 151 ... In modern workplaces with rapidly changing skill requirements, suitable training and learning environments play a key role for companies to remain competitive, effective and ensure job satisfaction. To provide an immersive, interactive, and ... ...

    Abstract 141

    151

    In modern workplaces with rapidly changing skill requirements, suitable training and learning environments play a key role for companies to remain competitive, effective and ensure job satisfaction. To provide an immersive, interactive, and engaging learning experience, Virtual Reality (VR) has emerged as a revolutionary technology. Especially when erroneous behaviour is associated with severe consequences or great resources, VR offers the opportunity to explore actions and visualize consequences in safely and at affordable costs. In addition, it provides an easy way to personalize educational content, learning speed, and/or format to the individual to guarantee a good fit with skills and needs. This is decisive, since insufficient or excessive workload during training sessions results in demotivation and reduced performance. In the latter case, persistent professional exhaustion, pressure to succeed and stress can lead to long-term psychological consequences for employees. Besides skill and ability, current physical conditions (e.g., illness or fatigue) and psychological states (e.g., motivation) also affect the learning performance. To identify and monitor individual mental states, Brain-Computer Interfaces (BCI) measuring neurophysiological activation patterns, e.g., with an electroencephalography (EEG), or functional near-infrared spectroscopy (fNIRS) can be integrated in a VR-learning environment. Recently, fNIRS, a mobile optical brain imaging technique, has become popular for real-world applications due to its good usability, portability, and ease of use. For the reliable online decoding of mental states, informative neuronal patterns, suitable methods for pre-processing and artefact removal, as well as efficient machine learning algorithms for the classification need to be explored. We, therefore, investigated and decoded different working memory states in a free moving fNIRS experiment presented in VR. different working memory states in a free moving fNIRS VR experiment and the possibility ...
    Keywords Brain-computer interfaces ; BCI ; Functional near-infrared spectroscopy ; FNIRS ; Visuo-spatial working memory ; Learning ; Machine learning
    Subject code 150
    Language English
    Publishing country de
    Document type Conference proceedings ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Systematic review and meta-analysis of preoperative predictors for early mortality following hip fracture surgery.

    Bui, Michael / Nijmeijer, Wieke S / Hegeman, Johannes H / Witteveen, Annemieke / Groothuis-Oudshoorn, Catharina G M

    Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA

    2023  Volume 35, Issue 4, Page(s) 561–574

    Abstract: Hip fractures are a global health problem with a high postoperative mortality rate. Preoperative predictors for early mortality could be used to optimise and personalise healthcare strategies. This study aimed to identify predictors for early mortality ... ...

    Abstract Hip fractures are a global health problem with a high postoperative mortality rate. Preoperative predictors for early mortality could be used to optimise and personalise healthcare strategies. This study aimed to identify predictors for early mortality following hip fracture surgery. Cohort studies examining independent preoperative predictors for mortality following hip fracture surgery were identified through a systematic search on Scopus and PubMed. Predictors for 30-day mortality were the primary outcome, and predictors for mortality within 1 year were secondary outcomes. Primary outcomes were analysed with random-effects meta-analyses. Confidence in the cumulative evidence was assessed using the GRADE criteria. Secondary outcomes were synthesised narratively. Thirty-three cohort studies involving 462,699 patients were meta-analysed. Five high-quality evidence predictors for 30-day mortality were identified: age per year (OR: 1.06, 95% CI: 1.04-1.07), ASA score ≥ 3 (OR: 2.69, 95% CI: 2.12-3.42), male gender (OR: 2.00, 95% CI: 1.85-2.18), institutional residence (OR: 1.81, 95% CI: 1.31-2.49), and metastatic cancer (OR: 2.83, 95% CI: 2.58-3.10). Additionally, six moderate-quality evidence predictors were identified: chronic renal failure, dementia, diabetes, low haemoglobin, heart failures, and a history of any malignancy. Weak evidence was found for non-metastatic cancer. This review found relevant preoperative predictors which could be used to identify patients who are at high risk of 30-day mortality following hip fracture surgery. For some predictors, the prognostic value could be increased by further subcategorising the conditions by severity.
    MeSH term(s) Humans ; Male ; Hip Fractures/surgery ; Diabetes Mellitus ; Neoplasms ; Risk Factors
    Language English
    Publishing date 2023-11-24
    Publishing country England
    Document type Meta-Analysis ; Systematic Review ; Journal Article ; Review
    ZDB-ID 1064892-6
    ISSN 1433-2965 ; 0937-941X
    ISSN (online) 1433-2965
    ISSN 0937-941X
    DOI 10.1007/s00198-023-06942-0
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Skin cancer biopsy and detection rates with total body skin examination: A cross-sectional retrospective analysis.

    Sherban, Alexander / Waseh, Shayan / Hugo, Audra / Bui, Michael / Daskalakis, Constantine / Jones, Elizabeth

    Journal of the American Academy of Dermatology

    2021  Volume 86, Issue 4, Page(s) 929–931

    MeSH term(s) Biopsy ; Cross-Sectional Studies ; Humans ; Retrospective Studies ; Skin/pathology ; Skin Neoplasms/diagnosis ; Skin Neoplasms/pathology
    Language English
    Publishing date 2021-03-23
    Publishing country United States
    Document type Letter
    ZDB-ID 603641-7
    ISSN 1097-6787 ; 0190-9622
    ISSN (online) 1097-6787
    ISSN 0190-9622
    DOI 10.1016/j.jaad.2021.03.061
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Confusion, Ataxia, and Wide-Complex Tachycardia: What Caused This Arrhythmia?

    Price, Justin / Shah, Jinesh / Bui, Michael Q / Chiles, Christopher D

    Texas Heart Institute journal

    2018  Volume 45, Issue 1, Page(s) 48–49

    MeSH term(s) Adult ; Ataxia/complications ; Confusion/complications ; Electrocardiography ; Female ; Humans ; Tachycardia, Ventricular/etiology ; Tachycardia, Ventricular/physiopathology
    Language English
    Publishing date 2018
    Publishing country United States
    Document type Case Reports ; Journal Article
    ZDB-ID 604761-0
    ISSN 1526-6702 ; 0730-2347
    ISSN (online) 1526-6702
    ISSN 0730-2347
    DOI 10.14503/THIJ-17-6444
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Brain Oscillation Entrainment by Perceptible and Non-perceptible Rhythmic Light Stimulation.

    Lingelbach, Katharina / Dreyer, Alexander M / Schöllhorn, Isabel / Bui, Michael / Weng, Michael / Diederichs, Frederik / Rieger, Jochem W / Petermann-Stock, Ina / Vukelić, Mathias

    Frontiers in neuroergonomics

    2021  Volume 2, Page(s) 646225

    Abstract: Objective and Background: ...

    Abstract Objective and Background:
    Language English
    Publishing date 2021-04-14
    Publishing country Switzerland
    Document type Journal Article
    ISSN 2673-6195
    ISSN (online) 2673-6195
    DOI 10.3389/fnrgo.2021.646225
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Conference proceedings ; Online: Real-Time Feedback of Subjective Affect and Working Memory Load Based on Neurophysiological Activity

    Gado, Sabrina / Lingelbach, Katharina / Bui, Michael / Rieger, Jochem W. / Vukelic, Mathias

    2021  

    Abstract: S.80-87 ... We investigated the effects of feedback on users' performance during a cognitive task with concurrent emotional distraction. Our aim was to provide participants with insights into their current affective and cognitive state by measuring and ... ...

    Abstract S.80-87

    We investigated the effects of feedback on users' performance during a cognitive task with concurrent emotional distraction. Our aim was to provide participants with insights into their current affective and cognitive state by measuring and decoding brain activity. Therefore, a real-time preprocessing, analyzing, and visualization routine was developed based on electroencephalographic (EEG) data measured during a primary study. To explore users' behavioral and neurophysiological reactions, error-tolerance as well as possibilities to improve feedback accuracy by the means of feedback-based event-related potentials (ERPs), we provided either legit or inappropriate sham feedback in a second study. The kind of feedback (legit or inappropriate) had only marginal influence on participants' subsequent performance. On a neuronal level, we did not observe differences in the ERPs evoked by the legit and inappropriate feedback. In qualitative interviews, participants evaluated the feedback as interesting but also sometimes irritating due to odd feedback trials. Our study emphasizes the importance of performance accuracy and transparency towards users regarding the underlying feedback computations.
    Subject code 150
    Language English
    Publishing country de
    Document type Conference proceedings ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: To cath or not to cath?

    Bui, Michael / Tinning, Meghan

    The virtual mentor : VM

    2010  Volume 12, Issue 1, Page(s) 27–30

    Language English
    Publishing date 2010
    Publishing country United States
    Document type Journal Article
    ISSN 1937-7010
    ISSN (online) 1937-7010
    DOI 10.1001/virtualmentor.2010.12.1.cprl1-1001
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Brain Oscillation Entrainment by Perceptible and Non-perceptible Rhythmic Light Stimulation

    Lingelbach, Katharina / Dreyer, Alexander M. / Schöllhorn, Isabel / Bui, Michael / Weng, Michael / Diederichs, Frederik / Rieger, Jochem W. / Petermann-Stock, Ina / Vukelic, Mathias

    Fraunhofer IAO

    2021  

    Abstract: Objective and Background: Decades of research in the field of steady-state visual evoked potentials (SSVEPs) have revealed great potential of rhythmic light stimulation for brain-computer interfaces. Additionally, rhythmic light stimulation provides a ... ...

    Abstract Objective and Background: Decades of research in the field of steady-state visual evoked potentials (SSVEPs) have revealed great potential of rhythmic light stimulation for brain-computer interfaces. Additionally, rhythmic light stimulation provides a non-invasive method for entrainment of oscillatory activity in the brain. Especially effective protocols enabling non-perceptible rhythmic stimulation and, thereby, reducing eye fatigue and user discomfort are favorable. Here, we investigate effects of (1) perceptible and (2) non-perceptible rhythmic light stimulation as well as attention-based effects of the stimulation by asking participants to focus (a) on the stimulation source directly in an overt attention condition or (b) on a cross-hair below the stimulation source in a covert attention condition. Method: SSVEPs at 10 Hz were evoked with a light-emitting diode (LED) driven by frequency-modulated signals and amplitudes of the current intensity either below or above a previously estimated individual threshold. Furthermore, we explored the effect of attention by asking participants to fixate on the LED directly in the overt attention condition and indirectly attend it in the covert attention condition. By measuring electroencephalography, we analyzed differences between conditions regarding the detection of reliable SSVEPs via the signal-to-noise ratio (SNR) and functional connectivity in occipito-frontal(-central) regions. Results: We could observe SSVEPs at 10 Hz for the perceptible and non-perceptible rhythmic light stimulation not only in the overt but also in the covert attention condition. The SNR and SSVEP amplitudes did not differ between the conditions and SNR values were in all except one participant above significance thresholds suggested by previous literature indicating reliable SSVEP responses. No difference between the conditions could be observed in the functional connectivity in occipito-frontal(-central) regions. Conclusion: The finding of robust SSVEPs even for non-intrusive rhythmic stimulation protocols below an individual perceptibility threshold and without direct fixation on the stimulation source reveals strong potential as a safe stimulation method for oscillatory entrainment in naturalistic applications.
    Subject code 150
    Language English
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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