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1.
  • Alme, Tomas Nordheim, et al. (författare)
  • Chronic fatigue syndromes: real illnesses that people can recover from
  • 2023
  • Ingår i: Scandinavian Journal of Primary Health Care. - : TAYLOR & FRANCIS LTD. - 0281-3432 .- 1502-7724. ; 41:4, s. 372-376
  • Tidskriftsartikel (refereegranskat)abstract
    • The Oslo Chronic Fatigue Consortium consists of researchers and clinicians who question the current narrative that chronic fatigue syndromes, including post-covid conditions, are incurable diseases. Instead, we propose an alternative view, based on research, which offers more hope to patients. Whilst we regard the symptoms of these conditions as real, we propose that they are more likely to reflect the brains response to a range of biological, psychological, and social factors, rather than a specific disease process. Possible causes include persistent activation of the neurobiological stress response, accompanied by associated changes in immunological, hormonal, cognitive and behavioural domains. We further propose that the symptoms are more likely to persist if they are perceived as threatening, and all activities that are perceived to worsen them are avoided. We also question the idea that the best way to cope with the illness is by prolonged rest, social isolation, and sensory deprivation.Instead, we propose that recovery is often possible if patients are helped to adopt a less threatening understanding of their symptoms and are supported in a gradual return to normal activities. Finally, we call for a much more open and constructive dialogue about these conditions. This dialogue should include a wider range of views, including those of patients who have recovered from them.
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2.
  • Enblom-Larsson, Anneli, et al. (författare)
  • Thromboembolic events, major bleeding and mortality in essential thrombocythaemia and polycythaemia vera : a matched nationwide population-based study
  • 2024
  • Ingår i: British Journal of Haematology. - : John Wiley & Sons. - 0007-1048 .- 1365-2141. ; 204:5, s. 1740-1751
  • Tidskriftsartikel (refereegranskat)abstract
    • Thromboembolic events and bleeding are known complications in essential thrombocythaemia (ET) and polycythaemia vera (PV). Using multiple Swedish health care registers, we assessed the rate of arterial and venous events, major bleeding, all-cause stroke and all-cause mortality in ET and PV compared to matched controls. For each patient with ET (n = 3141) and PV (n = 2604), five matched controls were randomly selected. In total, 327 and 405 arterial or venous events were seen in the group of ET and PV patients respectively. Compared to corresponding controls, the rate of venous thromboembolism, major bleeding and all-cause mortality per 100 treatment years was significantly increased among both ET (0.63, 0.79 and 3.70) and PV patients (0.94, 1.20 and 4.80). The PV patients also displayed a significantly higher rate of arterial events and all-cause stroke compared to controls. When dividing the cohort into age groups, we found a significantly higher rate of arterial and venous events in all age groups of PV patients, and the rate of all-cause mortality was significantly higher in both ET and PV patients in all ages above the age of 50. This study confirms that PV and ET are diseases truly marked by thromboembolic complications and bleeding.
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4.
  • Schmitz, Alexander, et al. (författare)
  • Longitudinal minimal residual disease assessment in multiple myeloma patients in complete remission : results from the NMSG flow-MRD substudy within the EMN02/HO95 MM trial
  • 2022
  • Ingår i: BMC Cancer. - : BMC. - 1471-2407. ; 22:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Multiple myeloma remains an incurable disease with multiple relapses due to residual myeloma cells in the bone marrow of patients after therapy. Presence of small number of cancer cells in the body after cancer treatment, called minimal residual disease, has been shown to be prognostic for progression-free and overall survival. However, for multiple myeloma, it is unclear whether patients attaining minimal residual disease negativity may be candidates for treatment discontinuation. We investigated, if longitudinal flow cytometry-based monitoring of minimal residual disease (flow-MRD) may predict disease progression earlier and with higher sensitivity compared to biochemical assessments. Methods: Patients from the Nordic countries with newly diagnosed multiple myeloma enrolled in the European-Myeloma-Network-02/Hovon-95 (EMN02/HO95) trial and undergoing bone marrow aspiration confirmation of complete response, were eligible for this Nordic Myeloma Study Group (NMSG) substudy. Longitdudinal flow-MRD assessment of bone marrow samples was performed to identify and enumerate residual malignant plasma cells until observed clinical progression. Results: Minimal residual disease dynamics were compared to biochemically assessed changes in serum free light chain and M-component. Among 20 patients, reaching complete response or stringent complete response during the observation period, and with >= 3 sequential flow-MRD assessments analysed over time, increasing levels of minimal residual disease in the bone marrow were observed in six cases, preceding biochemically assessed disease and clinical progression by 5.5 months and 12.6 months (mean values), respectively. Mean malignant plasma cells doubling time for the six patients was 1.8 months (95% CI, 1.4-2.3 months). Minimal malignant plasma cells detection limit was 4 x 10-5. Conclusions: Flow-MRD is a sensitive method for longitudinal monitoring of minimal residual disease dynamics in multiple myeloma patients in complete response. Increasing minimal residual disease levels precedes biochemically assessed changes and is an early indicator of subsequent clinical progression.
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5.
  • Walter, Susanna, et al. (författare)
  • Measuring the impact of gastrointestinal inconvenience and symptoms on perceived health in the general population - validation of the Short Health Scale for gastrointestinal symptoms (SHS-GI)
  • 2021
  • Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 56:12, s. 1406-1463
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives Gastrointestinal (GI) symptoms are intimately related to our wellbeing. The Short Health Scale for GI symptoms (SHS-GI) is a simple questionnaire to measure the impact of GI inconvenience and symptoms on quality of life. The aim was to validate the SHS-GI in a general population sample and to compare it with SHS-data across different patient groups.Method A subsample of 170 participants from a population-based colonoscopy study completed the Rome II questionnaire, GI diaries, psychological questionnaire (hospital anxiety and depression scale) and SHS-GI at follow-up investigation. Psychometric properties of SHS-GI as an overall score were determined by performing a confirmatory factor analysis (CFA). Spearman correlation between SHS total score and symptoms was calculated in the general population sample. SHS-GI data was compared with SHS data from patients with inflammatory bowel disease (IBD) and fecal incontinence (FI).Results As expected, the general population rated their impact of GI inconvenience on quality of life as better than the patient populations in terms of all aspects of the SHS-GI. The CFA showed a good model fit meeting all fit criteria in the general population. Cronbach's alpha for the total scale was 0.80 in the general population sample and ranged from 0.72 in the FI sample to 0.88 and 0.89 in the IBD samples.Conclusions SHS-GI demonstrated appropriate psychometric properties in a sample of the normal population. We suggest that SHS-GI is a valid simple questionnaire suitable for measuring the impact of GI symptoms and inconvenience on quality of life in both general and patient populations.
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6.
  • Adolfsson, Daniel, 1992-, et al. (författare)
  • CFEAR Radarodometry - Conservative Filtering for Efficient and Accurate Radar Odometry
  • 2021
  • Ingår i: IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2021). - : IEEE. - 9781665417143 - 9781665417150 ; , s. 5462-5469
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents the accurate, highly efficient, and learning-free method CFEAR Radarodometry for large-scale radar odometry estimation. By using a filtering technique that keeps the k strongest returns per azimuth and by additionally filtering the radar data in Cartesian space, we are able to compute a sparse set of oriented surface points for efficient and accurate scan matching. Registration is carried out by minimizing a point-to-line metric and robustness to outliers is achieved using a Huber loss. We were able to additionally reduce drift by jointly registering the latest scan to a history of keyframes and found that our odometry method generalizes to different sensor models and datasets without changing a single parameter. We evaluate our method in three widely different environments and demonstrate an improvement over spatially cross-validated state-of-the-art with an overall translation error of 1.76% in a public urban radar odometry benchmark, running at 55Hz merely on a single laptop CPU thread.
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7.
  • Adolfsson, Daniel, 1992-, et al. (författare)
  • CorAl : Introspection for robust radar and lidar perception in diverse environments using differential entropy
  • 2022
  • Ingår i: Robotics and Autonomous Systems. - : Elsevier. - 0921-8890 .- 1872-793X. ; 155
  • Tidskriftsartikel (refereegranskat)abstract
    • Robust perception is an essential component to enable long-term operation of mobile robots. It depends on failure resilience through reliable sensor data and pre-processing, as well as failure awareness through introspection, for example the ability to self-assess localization performance. This paper presents CorAl: a principled, intuitive, and generalizable method to measure the quality of alignment between pairs of point clouds, which learns to detect alignment errors in a self-supervised manner. CorAl compares the differential entropy in the point clouds separately with the entropy in their union to account for entropy inherent to the scene. By making use of dual entropy measurements, we obtain a quality metric that is highly sensitive to small alignment errors and still generalizes well to unseen environments. In this work, we extend our previous work on lidar-only CorAl to radar data by proposing a two-step filtering technique that produces high-quality point clouds from noisy radar scans. Thus, we target robust perception in two ways: by introducing a method that introspectively assesses alignment quality, and by applying it to an inherently robust sensor modality. We show that our filtering technique combined with CorAl can be applied to the problem of alignment classification, and that it detects small alignment errors in urban settings with up to 98% accuracy, and with up to 96% if trained only in a different environment. Our lidar and radar experiments demonstrate that CorAl outperforms previous methods both on the ETH lidar benchmark, which includes several indoor and outdoor environments, and the large-scale Oxford and MulRan radar data sets for urban traffic scenarios. The results also demonstrate that CorAl generalizes very well across substantially different environments without the need of retraining.
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8.
  • Adolfsson, Daniel, 1992-, et al. (författare)
  • CorAl – Are the point clouds Correctly Aligned?
  • 2021
  • Ingår i: 10th European Conference on Mobile Robots (ECMR 2021). - : IEEE.
  • Konferensbidrag (refereegranskat)abstract
    • In robotics perception, numerous tasks rely on point cloud registration. However, currently there is no method that can automatically detect misaligned point clouds reliably and without environment-specific parameters. We propose "CorAl", an alignment quality measure and alignment classifier for point cloud pairs, which facilitates the ability to introspectively assess the performance of registration. CorAl compares the joint and the separate entropy of the two point clouds. The separate entropy provides a measure of the entropy that can be expected to be inherent to the environment. The joint entropy should therefore not be substantially higher if the point clouds are properly aligned. Computing the expected entropy makes the method sensitive also to small alignment errors, which are particularly hard to detect, and applicable in a range of different environments. We found that CorAl is able to detect small alignment errors in previously unseen environments with an accuracy of 95% and achieve a substantial improvement to previous methods.
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9.
  • Adolfsson, Daniel, 1992-, et al. (författare)
  • Lidar-Level Localization With Radar? The CFEAR Approach to Accurate, Fast, and Robust Large-Scale Radar Odometry in Diverse Environments
  • 2023
  • Ingår i: IEEE Transactions on robotics. - : IEEE. - 1552-3098 .- 1941-0468. ; 39:2, s. 1476-1495
  • Tidskriftsartikel (refereegranskat)abstract
    • This article presents an accurate, highly efficient, and learning-free method for large-scale odometry estimation using spinning radar, empirically found to generalize well across very diverse environments—outdoors, from urban to woodland, and indoors in warehouses and mines—without changing parameters. Our method integrates motion compensation within a sweep with one-to-many scan registration that minimizes distances between nearby oriented surface points and mitigates outliers with a robust loss function. Extending our previous approach conservative filtering for efficient and accurate radar odometry (CFEAR), we present an in-depth investigation on a wider range of datasets, quantifying the importance of filtering, resolution, registration cost and loss functions, keyframe history, and motion compensation. We present a new solving strategy and configuration that overcomes previous issues with sparsity and bias, and improves our state-of-the-art by 38%, thus, surprisingly, outperforming radar simultaneous localization and mapping (SLAM) and approaching lidar SLAM. The most accurate configuration achieves 1.09% error at 5 Hz on the Oxford benchmark, and the fastest achieves 1.79% error at 160 Hz.
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10.
  • Adolfsson, Daniel, 1992-, et al. (författare)
  • Oriented surface points for efficient and accurate radar odometry
  • 2021
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents an efficient and accurate radar odometry pipeline for large-scale localization. We propose a radar filter that keeps only the strongest reflections per-azimuth that exceeds the expected noise level. The filtered radar data is used to incrementally estimate odometry by registering the current scan with a nearby keyframe. By modeling local surfaces, we were able to register scans by minimizing a point-to-line metric and accurately estimate odometry from sparse point sets, hence improving efficiency. Specifically, we found that a point-to-line metric yields significant improvements compared to a point-to-point metric when matching sparse sets of surface points. Preliminary results from an urban odometry benchmark show that our odometry pipeline is accurate and efficient compared to existing methods with an overall translation error of 2.05%, down from 2.78% from the previously best published method, running at 12.5ms per frame without need of environmental specific training. 
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11.
  • Adolfsson, Daniel, 1992- (författare)
  • Robust large-scale mapping and localization : Combining robust sensing and introspection
  • 2023
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The presence of autonomous systems is rapidly increasing in society and industry. To achieve successful, efficient, and safe deployment of autonomous systems, they must be navigated by means of highly robust localization systems. Additionally, these systems need to localize accurately and efficiently in realtime under adverse environmental conditions, and within considerably diverse and new previously unseen environments.This thesis focuses on investigating methods to achieve robust large-scale localization and mapping, incorporating robustness at multiple stages. Specifically, the research explores methods with sensory robustness, utilizing radar, which exhibits tolerance to harsh weather, dust, and variations in lighting conditions. Furthermore, the thesis presents methods with algorithmic robustness, which prevent failures by incorporating introspective awareness of localization quality. This thesis aims to answer the following research questions:How can radar data be efficiently filtered and represented for robust radar odometry? How can accurate and robust odometry be achieved with radar? How can localization quality be assessed and leveraged for robust detection of localization failures? How can self-awareness of localization quality be utilized to enhance the robustness of a localization system?While addressing these research questions, this thesis makes the following contributions to large-scale localization and mapping: A method for robust and efficient radar processing and state-of-the-art odometry estimation, and a method for self-assessment of localization quality and failure detection in lidar and radar localization. Self-assessment of localization quality is integrated into robust systems for large-scale Simultaneous Localization And Mapping, and rapid global localization in prior maps. These systems leverage self-assessment of localization quality to improve performance and prevent failures in loop closure and global localization, and consequently achieve safe robot localization.The methods presented in this thesis were evaluated through comparative assessments of public benchmarks and real-world data collected from various industrial scenarios. These evaluations serve to validate the effectiveness and reliability of the proposed approaches. As a result, this research represents a significant advancement toward achieving highly robust localization capabilities with broad applicability.
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12.
  • Adolfsson, Daniel, 1992-, et al. (författare)
  • TBV Radar SLAM - Trust but Verify Loop Candidates
  • 2023
  • Ingår i: IEEE Robotics and Automation Letters. - : IEEE. - 2377-3766. ; 8:6, s. 3613-3620
  • Tidskriftsartikel (refereegranskat)abstract
    • Robust SLAM in large-scale environments requires fault resilience and awareness at multiple stages, from sensing and odometry estimation to loop closure. In this work, we present TBV (Trust But Verify) Radar SLAM, a method for radar SLAM that introspectively verifies loop closure candidates. TBV Radar SLAM achieves a high correct-loop-retrieval rate by combining multiple place-recognition techniques: tightly coupled place similarity and odometry uncertainty search, creating loop descriptors from origin-shifted scans, and delaying loop selection until after verification. Robustness to false constraints is achieved by carefully verifying and selecting the most likely ones from multiple loop constraints. Importantly, the verification and selection are carried out after registration when additional sources of loop evidence can easily be computed. We integrate our loop retrieval and verification method with a robust odometry pipeline within a pose graph framework. By evaluation on public benchmarks we found that TBV Radar SLAM achieves 65% lower error than the previous state of the art. We also show that it generalizes across environments without needing to change any parameters. We provide the open-source implementation at https://github.com/dan11003/tbv_slam_public
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13.
  • Alhashimi, Anas, 1978-, et al. (författare)
  • BFAR – Bounded False Alarm Rate detector for improved radar odometry estimation
  • 2021
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents a new detector for filtering noise from true detections in radar data, which improves the state of the art in radar odometry. Scanning Frequency-Modulated Continuous Wave (FMCW) radars can be useful for localisation and mapping in low visibility, but return a lot of noise compared to (more commonly used) lidar, which makes the detection task more challenging. Our Bounded False-Alarm Rate (BFAR) detector is different from the classical Constant False-Alarm Rate (CFAR) detector in that it applies an affine transformation on the estimated noise level after which the parameters that minimize the estimation error can be learned. BFAR is an optimized combination between CFAR and fixed-level thresholding. Only a single parameter needs to be learned from a training dataset. We apply BFAR tothe use case of radar odometry, and adapt a state-of-the-art odometry pipeline (CFEAR), replacing its original conservative filtering with BFAR. In this way we reduce the state-of-the-art translation/rotation odometry errors from 1.76%/0.5◦/100 m to 1.55%/0.46◦/100 m; an improvement of 12.5%.
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14.
  • Alifier, Marek, et al. (författare)
  • Cardiac Surgery is Associated with Biomarker Evidence of Neuronal Damage.
  • 2020
  • Ingår i: Journal of Alzheimer's disease : JAD. - 1875-8908. ; 74:4, s. 1211-1220
  • Tidskriftsartikel (refereegranskat)abstract
    • Anesthesia and surgery is commonly associated with central nervous system sequelae and cognitive symptoms, which may be caused by neuronal injury. Neuronal injury can be monitored by plasma concentrations of the neuronal biomarkers tau and neurofilament light protein (NFL). Currently, there are no studies examining whether neuronal injury varies between surgical procedures.Our aim was to investigate if neuronal damage is more frequent after cardiac than after otolaryngeal surgery, as estimated by tau and NFL concentrations in plasma.Blood samples were drawn before, during, and after surgery and concentrations of tau, NFL, Aβ40, and Aβ42 were measured in 25 patients undergoing cardiac surgery (9 off-pump and 16 on-pump) and 26 patients undergoing otolaryngeal surgery.Tau increased during surgery (1752%, p=0.0001) and NFL rose seven days post-surgery (1090%, p<0.0001) in patients undergoing cardiac surgery; even more in patients on-pump than off-pump. No changes were observed in patients undergoing otolaryngeal surgery and only minor fluctuations were observed for Aβ40 and Aβ42.Cardiac surgery is associated with neuronal injury, which is aggravated by extracorporeal circulation. Analyses of NFL and tau in blood may guide development of surgical procedures to minimize neuronal damage, and may also be used in longitudinal clinical studies to assess the relationship of surgery with future neurocognitive impairment or dementia.
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15.
  • Andreasson, Annika, et al. (författare)
  • A Census of Swedish Government Administrative Authority Employee Communications on Cybersecurity during the COVID-19 Pandemic
  • 2020
  • Ingår i: 2020 IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining (ASONAM). - : IEEE.
  • Konferensbidrag (refereegranskat)abstract
    • Cybersecurity is the backbone of a successful digitalization of society, and cyber situation awareness is an essential aspect of managing it. The COVID-19 pandemic has sped up an already ongoing digitalization of Swedish government agencies, but the cybersecurity maturity level varies across agencies. In this study, we conduct a census of Swedish government administrative authority communications on cybersecurity to employees at the beginning of the COVID-19 pandemic. The census shows that the employee communications in the beginning of the pandemic to a greater extent have focused on first-order risks, such as video meetings and telecommuting, rather than on second-order risks, such as invoice fraud or social engineering. We also find that almost two thirds of the administrative authorities have not yet implemented, but only initiated or documented, their cybersecurity policies.
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16.
  • Andreasson, Annika, et al. (författare)
  • A Census of Swedish Public Sector Employee Communication on Cybersecurity during the COVID-19 Pandemic
  • 2021
  • Ingår i: Proceedings of the International Conference on Cyber Situational Awareness, Data Analytics and Assessment, CyberSA 2021. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1-8
  • Konferensbidrag (refereegranskat)abstract
    • The COVID-19 pandemic has accelerated the digitalization of the Swedish public sector, and to ensure the success of this ongoing process cybersecurity plays an integral part. While Sweden has come far in digitalization, the maturity of cybersecurity work across entities covers a wide range. One way of improving cybersecurity is through communication, thereby enhancing employee cyber situation awareness. In this paper, we conduct a census of Swedish public sector employee communication on cybersecurity at the beginning of the COVID-19 pandemic using questionnaires. The study shows that public sector entities find the same sources of information useful for their cybersecurity work. We find that nearly two thirds of administrative authorities and almost three quarters of municipalities are not yet at the implemented cybersecurity level. We also find that 71 % of municipalities have less than one dedicated staff for cybersecurity.
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17.
  • Andreasson, Henrik, 1977-, et al. (författare)
  • A Local Planner for Accurate Positioning for a Multiple Steer-and-Drive Unit Vehicle Using Non-Linear Optimization
  • 2022
  • Ingår i: Sensors. - : MDPI. - 1424-8220. ; 22:7
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents a local planning approach that is targeted for pseudo-omnidirectional vehicles: that is, vehicles that can drive sideways and rotate on the spot. This local planner—MSDU–is based on optimal control and formulates a non-linear optimization problem formulation that exploits the omni-motion capabilities of the vehicle to drive the vehicle to the goal in a smooth and efficient manner while avoiding obstacles and singularities. MSDU is designed for a real platform for mobile manipulation where one key function is the capability to drive in narrow and confined areas. The real-world evaluations show that MSDU planned paths that were smoother and more accurate than a comparable local path planner Timed Elastic Band (TEB), with a mean (translational, angular) error for MSDU of (0.0028 m, 0.0010 rad) compared to (0.0033 m, 0.0038 rad) for TEB. MSDU also generated paths that were consistently shorter than TEB, with a mean (translational, angular) distance traveled of (0.6026 m, 1.6130 rad) for MSDU compared to (0.7346 m, 3.7598 rad) for TEB.
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18.
  • Andreasson, M., et al. (författare)
  • Parkinson's disease with restless legs syndrome-an in vivo corneal confocal microscopy study
  • 2021
  • Ingår i: npj Parkinson's Disease. - : Springer Science and Business Media LLC. - 2373-8057. ; 7:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Small fiber neuropathy (SFN) has been suggested as a trigger of restless legs syndrome (RLS). An increased prevalence of peripheral neuropathy has been demonstrated in Parkinson's disease (PD). We aimed to investigate, in a cross-sectional manner, whether SFN is overrepresented in PD patients with concurrent RLS relative to PD patients without RLS, using in vivo corneal confocal microscopy (IVCCM) and quantitative sensory testing (QST) as part of small fiber assessment. Study participants comprised of age- and sex-matched PD patients with (n = 21) and without RLS (n = 21), and controls (n = 13). Diagnosis of RLS was consolidated with the sensory suggested immobilization test. Assessments included nerve conduction studies (NCS), Utah Early Neuropathy Scale (UENS), QST, and IVCCM, with automated determination of corneal nerve fiber length (CNFL) and branch density (CNBD) from wide-area mosaics of the subbasal nerve plexus. Plasma neurofilament light (p-NfL) was determined as a measure of axonal degeneration. No significant differences were found between groups when comparing CNFL (p = 0.81), CNBD (p = 0.92), NCS (p = 0.82), and QST (minimum p = 0.54). UENS scores, however, differed significantly (p = 0.001), with post-hoc pairwise testing revealing higher scores in both PD groups relative to controls (p = 0.018 and p = 0.001). Analysis of all PD patients (n = 42) revealed a correlation between the duration of l-dopa therapy and CNBD (rho = -0.36, p = 0.022), and p-NfL correlated with UENS (rho = 0.35, p = 0.026) and NCS (rho = -0.51, p = 0.001). Small and large fiber neuropathy do not appear to be associated with RLS in PD. Whether peripheral small and/or large fiber pathology associates with central neurodegeneration in PD merits further longitudinal studies.
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19.
  • Andreasson, Ulf, 1968, et al. (författare)
  • Assessing the commutability of candidate reference materials for the harmonization of neurofilament light measurements in blood
  • 2023
  • Ingår i: Clinical Chemistry and Laboratory Medicine. - : Walter de Gruyter GmbH. - 1434-6621 .- 1437-4331. ; 61:7, s. 1245-1254
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives Neurofilament light chain (NfL) concentration in blood is a biomarker of neuro-axonal injury in the nervous system and there now exist several assays with high enough sensitivity to measure NfL in serum and plasma. There is a need for harmonization with the goal of creating a certified reference material (CRM) for NfL and an early step in such an effort is to determine the best matrix for the CRM. This is done in a commutability study and here the results of the first one for NfL in blood is presented.Methods Forty paired individual serum and plasma samples were analyzed for NfL on four different analytical platforms. Neat and differently spiked serum and plasma were evaluated for their suitability as a CRM using the difference in bias approach.Results The correlation between the different platforms with regards to measured NfL concentrations were very high (Spearman's rho >= 0.96). Samples spiked with cerebrospinal fluid (CSF) showed higher commutability compared to samples spiked with recombinant human NfL protein and serum seems to be a better choice than plasma as the matrix for a CRM.Conclusions The results from this first commutability study on NfL in serum/plasma showed that it is feasible to create a CRM for NfL in blood and that spiking should be done using CSF rather than with recombinant human NfL protein.
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20.
  • Andreasson, Ulf, 1968, et al. (författare)
  • Method and Clinical Validation of Biomarkers for Neurodegenerative Diseases
  • 2021
  • Ingår i: Cerebrospinal Fluid Biomarkers. Neuromethods, vol 168. Teunissen C.E., Zetterberg H. (eds). - New York, NY : Springer. - 0893-2336. - 9781071613184 ; , s. 163-173
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • In the Merriam-Webster dictionary, one definition of the word valid is “well-grounded or justifiable: being at once relevant and meaningful.” Validation is then the process of determining the degree of validity. From this broad definition, it follows that validations can be made in many different fields with quite different implications. When talking about validation, it is therefore important to specify the subject under scrutiny and in this chapter the focus will be on validation of biomarkers. © 2021, Springer Science+Business Media, LLC, part of Springer Nature.
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21.
  • Arunachalam, Ajay, 1985-, et al. (författare)
  • MSI-RPi : Affordable, Portable, and Modular Multispectral Imaging Prototype Suited to Operate in UV, Visible and Mid-Infrared Regions
  • 2022
  • Ingår i: Journal of Mobile Multimedia. - : River Publishers. - 1550-4646 .- 1550-4654. ; 18:3, s. 723-742
  • Tidskriftsartikel (refereegranskat)abstract
    • Digital plant inventory provides critical growth insights, given the associated data quality is good. Stable & high-quality image acquisition is critical for further examination. In this work, we showcase an affordable, portable, and modular spectral camera prototype, designed with open hardware’s and open-source software’s. The image sensors used were color, and infrared Pi micro-camera. The designed prototype presents the advantage as being low-cost and modular with respect to other general commercial market available spectral devices. The micro-size connected sensors make it a compact instrument that can be used for any general spectral acquisition purposes, along with the provision of custom selection of the bands, making the presented prototype design a Plug-nd-Play (PnP) setup that can be used in different wide application areas. The images acquired from our custom-built prototype were back-tested by performing image analysis and qualitative assessments. The image acquisition software, and processing algorithm has been programmed, which is bundled with our developed system. Further, an end-to-end automation script is integrated for the users to readily leverage the services on-demand. The design files, schematics, and all the related materials of the spectral block design is open-sourced with open-hardware license & is made available at https://github.com/ajayarunachalam/Multi-Spectral-Imaging-RaspberryPi-Design. The automated data acquisition scripts & the spectral image analysis done is made available at https://github.com/ajayarunachalam/SI-RPi.
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22.
  • Arunachalam, Ajay, 1985-, et al. (författare)
  • RaspberryPi‐Arduino (RPA) powered smart mirrored and reconfigurable IoT facility for plant science research
  • 2022
  • Ingår i: Internet Technology Letters. - : John Wiley & Sons. - 2476-1508. ; 5:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Continuous monitoring of crops is critical for the sustainability of agriculture. The effects of changes in temperature, light intensity, humidity, pH, soil moisture, gas intensities, etc. have an overall impact on the plant growth. Growth chambers are environmental controlled facilities which needs to be monitored round-the-clock. To improve both the reproducibility, and maintenance of such facilities, remote monitoring plays a very pivotal role. An automated re-configurable & persistent mirrored storage-based remote monitoring system is developed with low-cost open source hardwares and softwares. The system automates sensors deployment, storage (database, logs), and provides an elegant dashboard to visualize the real-time continuous data stream. We propose a new smart AGRO IoT system with robust data acquisition mechanism, and also propose two software component nodes, (i.e., Mirroring and Reconfiguration) running as an instance of the whole IoT facility. The former one is aimed to minimize/avoid the downtime, while the latter one is aimed to leverage the available cores, and better utilization of the computational resources. Our system can be easily deployed in growth chambers, greenhouses, CNC farming test-bed setup, cultivation plots, and further can be also extended to support large-farms with either using multiple individual standalone setup as heterogeneous instances of this facility, or by extending it as master-slave cluster configuration for communication as a single homogeneous instance. Our RaspberryPi-Arduino (RPA) powered solution is scalable, and provides stability for monitoring any environment continuously at ease.
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23.
  • Arunachalam, Ajay, 1985-, et al. (författare)
  • Real-time plant phenomics under robotic farming setup : A vision-based platform for complex plant phenotyping tasks
  • 2021
  • Ingår i: Computers & electrical engineering. - : Elsevier. - 0045-7906 .- 1879-0755. ; 92
  • Tidskriftsartikel (refereegranskat)abstract
    • Plant phenotyping in general refers to quantitative estimation of the plant's anatomical, ontogenetical, physiological and biochemical properties. Analyzing big data is challenging, and non-trivial given the different complexities involved. Efficient processing and analysis pipelines are the need of the hour with the increasing popularity of phenotyping technologies and sensors. Through this work, we largely address the overlapping object segmentation & localization problem. Further, we dwell upon multi-plant pipelines that pose challenges as detection and multi-object tracking becomes critical for single frame/set of frames aimed towards uniform tagging & visual features extraction. A plant phenotyping tool named RTPP (Real-Time Plant Phenotyping) is presented that can aid in the detection of single/multi plant traits, modeling, and visualization for agricultural settings. We compare our system with the plantCV platform. The relationship of the digital estimations, and the measured plant traits are discussed that plays a vital roadmap towards precision farming and/or plant breeding.
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24.
  • Arvidsson Rådestig, Maya, et al. (författare)
  • Cerebrospinal fluid biomarkers of axonal and synaptic degeneration in a population-based sample
  • 2023
  • Ingår i: Alzheimers Research & Therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 15:1
  • Tidskriftsartikel (refereegranskat)abstract
    • BackgroundNeurofilament light (NfL) and neurogranin (Ng) are promising candidate AD biomarkers, reflecting axonal and synaptic damage, respectively. Since there is a need to understand the synaptic and axonal damage in preclinical Alzheimer's disease (AD), we aimed to determine the cerebrospinal fluid (CSF) levels of NfL and Ng in cognitively unimpaired elderly from the Gothenburg H70 Birth Cohort Studies classified according to the amyloid/tau/neurodegeneration (A/T/N) system.MethodsThe sample consisted of 258 cognitively unimpaired older adults (age 70, 129 women and 129 men) from the Gothenburg Birth Cohort Studies. We compared CSF NfL and Ng concentrations in A/T/N groups using Student's T-test and ANCOVA.ResultsCSF NfL concentration was higher in the A-T-N+ group (p=0.001) and the A-T+N+ group (p=0.006) compared with A-T-N-. CSF Ng concentration was higher in the A-T-N+, A-T+N+, A+T-N+, and A+T+N+ groups (p<0.0001) compared with A-T-N-. We found no difference in NfL or Ng concentration in A+ compared with A- (disregarding T- and N- status), whereas those with N+ had higher concentrations of NfL and Ng compared with N- (p<0.0001) (disregarding A- and T- status).ConclusionsCSF NfL and Ng concentrations are increased in cognitively normal older adults with biomarker evidence of tau pathology and neurodegeneration.
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25.
  • Bazzana, Barbara, et al. (författare)
  • How-to Augmented Lagrangian on Factor Graphs
  • 2024
  • Ingår i: IEEE Robotics and Automation Letters. - : IEEE. - 2377-3766. ; 9:3, s. 2806-2813
  • Tidskriftsartikel (refereegranskat)abstract
    • Factor graphs are a very powerful graphical representation, used to model many problems in robotics. They are widely spread in the areas of Simultaneous Localization and Mapping (SLAM), computer vision, and localization. However, the physics of many real-world problems is better modeled through constraints, e.g., estimation in the presence of inconsistent measurements, or optimal control. Constraints handling is hard because the solution cannot be found by following the gradient descent direction as done by traditional factor graph solvers. The core idea of our method is to encapsulate the Augmented Lagrangian (AL) method in factors that can be integrated straightforwardly in existing factor graph solvers. Besides being a tool to unify different robotics areas, the modularity of factor graphs allows to easily combine multiple objectives and effectively exploiting the problem structure for efficiency. We show the generality of our approach by addressing three applications, arising from different areas: pose estimation, rotation synchronization and Model Predictive Control (MPC) of a pseudo-omnidirectional platform. We implemented our approach using C++ and ROS. Application results show that we can favorably compare against domain specific approaches.
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26.
  • Borngrund, Carl, 1992-, et al. (författare)
  • Automating the Short-Loading Cycle: Survey and Integration Framework
  • 2024
  • Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 14:11
  • Tidskriftsartikel (refereegranskat)abstract
    • The short-loading cycle is a construction task where a wheel loader scoops material from a nearby pile in order to move that material to the tipping body of a dump truck. The short-loading cycle is a vital task performed in high quantities and is often part of a more extensive never-ending process to move material for further refinement. This, together with the highly repetitive nature of the short-loading cycle, makes it a suitable candidate for automation. However, the short-loading cycle is a complex task where the mechanics of the wheel loader together with the interaction between the wheel loader and the environment needs to be considered. This must be achieved while maintaining some productivity goal and, concurrently, minimizing the used energy. The main objective of this work is to analyze the short-loading cycle, assess the current state of research in this field, and discuss the steps required to progress towards a minimal viable product consisting of individual automation solutions that can perform the short-loading cycle well enough to be used by early adopters. This is achieved through a comprehensive literature study and consequent analysis of the review results. From this analysis, the requirements of an MVP are defined and some gaps which are currently hindering the realization of the MVP are presented.
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27.
  • Borngrund, Carl, 1992- (författare)
  • Automation of Navigation During the Short-loading Cycle Using Machine Vision
  • 2022
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Earth-moving machines are machines used in a wide range of industries, such as the construction industry, to perform tasks related to earthworks.Currently, the vast majority of earth-moving machines are human-operated where expert operators perform these industry vital tasks.One such task is the short-loading cycle which is a repetitive work cycle performed in high quantities within the construction industry.This work cycle aims to use a wheel-loader to move material from a pile or from the ground to the tipping body of a dump truck.Not only is this task repetitive and performed in high quantities, but it is also representative of the knowledge required to perform a wide set of other work cycles, hence a good candidate for automation.Skilled operators use their sensory input to perform the tasks required, such as tactile, sound and sight.One of the most important senses leveraged during normal operations is sight, as it is used to locate dynamic objects and detect dangers.Thus to be able to replace the driver of an earth-moving machine with an autonomous system, the system requires similar vision capabilities.Machine Vision is a field where the goal is to use some type of vision sensor, such as cameras, to extract relevant high-level information from images or video streams.This thesis aims to examine how machine vision can be used within the short-loading cycle to facilitate performing said work cycle autonomously.The main findings in this thesis are threefold: Firstly, two knowledge gaps are identified in the domain of automation during the short-loading cycle.These relate to the loading of heterogeneous material and navigation during loading and unloading.Secondly, we show that it is possible to train a deep learning model to detect the cab, wheels and tipping body of a scale-model dump truck while mimicking the approach towards the load carrier during the short-loading cycle.This model can then be applied to real vehicles to detect the same objects, with no additional training.Lastly, we show that linear interpolation can be used to perform semi-automatic labelling of camera-based video data of the approach of a wheel-loader towards a dump truck during the short-loading cycle.This technique decreases the annotation workload by around 95% while retaining comparable performance.The future direction of this work includes using techniques such as reinforcement learning to teach a model to perform the navigation required during the short-loading cycle.Future work also includes using world models to learn representations of underlying structures in the environment, open-ended learning to transfer the learned knowledge to adjacent work cycles and using machine vision to find the point of attack for scooping heterogeneous material.
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28.
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29.
  • Borngrund, Carl, 1992- (författare)
  • Towards Deep-learning-based Autonomous Navigation in the Short-loading Cycle
  • 2023
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Earth-moving machines, such as wheel loaders, are a type of heavy-duty machinery used within the construction industry to perform vital tasks, such as digging, transporting, and mining applications. One of these tasks is the short-loading cycle, where an operator manoeuvres the wheel loader to move material from a pile to the tipping body of a dump truck, through navigation, scooping, and dumping. The short-loading cycle is a repetitive task performed in high quantities, often as part of a larger refinement process, making it interesting for automation.The main objective of this thesis work is to investigate challenges facing the automation of the short-loading cycle, focusing in particular on subtasks that can be efficiently addressed with deep learning methods. A secondary objective is to examine how alternative development paths, such as scale models, or simulations, can be used to enable data-driven automation of the short-loading cycle, as directly experimenting on real vehicles has a high associated cost when large numbers of timesteps are needed to gather enough data.To investigate the two objectives, the literature is systematically reviewed to identify research gaps, challenges, and the usage of deep learning techniques. Secondly, a set of deep learning techniques is investigated to address perception and actuation problems identified as challenging and important for the automation of the short-loading cycle.The investigation of deep learning techniques involves training and validating a realtime object detector neural network to identify key components (wheels, tipping body, and cab) on a scale model dump truck while testing on a real vehicle. This resulted in a localisation and classification degradation of only 14% between the scale model and the real dump truck, with no additional training. In addition, an examination to minimize the annotation workload of humans found that it is possible to decrease the workload by 95% while still retaining similar detection performance by leveraging linear interpolation.Lastly, this thesis presents an investigation regarding the usage of reinforcement learning for navigation during the short-loading cycle. The results indicate that training the agent in simulation is currently required as the agent obtains the maximum reward after timesteps in the order of millions before being capable of performing the task. The results suggest that the trained agent is capable of bridging the gap between simulation and reality to complete a simplified version of the navigation task during the short-loading cycle.The experiments presented in this thesis provide proof of concept that indicates deep learning techniques can aid in the realisation of an autonomous solution. Moreover, the results show that development paths allowing for experiments providing large numbers of timesteps can facilitate the practical use of such techniques.
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30.
  • Boulo, S., et al. (författare)
  • First amyloid β1-42 certified reference material for re-calibrating commercial immunoassays
  • 2020
  • Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 16:11, s. 1493-1503
  • Tidskriftsartikel (refereegranskat)abstract
    • Introduction: Reference materials based on human cerebrospinal fluid were certified for the mass concentration of amyloid beta (Aβ)1-42 (Aβ42). They are intended to be used to calibrate diagnostic assays for Aβ42. Methods: The three certified reference materials (CRMs), ERM-DA480/IFCC, ERM-DA481/IFCC and ERM-DA482/IFCC, were prepared at three concentration levels and characterized using isotope dilution mass spectrometry methods. Roche, EUROIMMUN, and Fujirebio used the three CRMs to re-calibrate their immunoassays. Results: The certified Aβ42 mass concentrations in ERM-DA480/IFCC, ERM-DA481/IFCC, and ERM-DA482/IFCC are 0.45, 0.72, and 1.22μg/L, respectively, with expanded uncertainties (k=2) of 0.07, 0.11, and 0.18μg/L, respectively. Before re-calibration, a good correlation (Pearson's r>0.97), yet large biases, were observed between results from different commercial assays. After re-calibration the between-assay bias was reduced to<5%. Discussion: The Aβ42 CRMs can ensure the equivalence of results between methods and across platforms for the measurement of Aβ42. © 2020 the Alzheimer's Association
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31.
  • Camu, W., et al. (författare)
  • Repeated 5-day cycles of low dose aldesleukin in amyotrophic lateral sclerosis (IMODALS): A phase 2a randomised, double-blind, placebo-controlled trial
  • 2020
  • Ingår i: EBioMedicine. - : Elsevier BV. - 2352-3964. ; 59
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Low-dose interleukin-2 (ld-IL-2) enhances regulatory T-cell (Treg) function in auto-inflammatory conditions. Neuroinflammation being a pathogenic feature of amyotrophic lateral sclerosis (ALS), we evaluated the pharmacodynamics and safety of ld-IL-2 in ALS subjects. Methods: We performed a single centre, parallel three-arm, randomised, double-blind, placebo-controlled study. Eligibility criteria included age < 75 years, disease duration < 5 years, riluzole treatment > 3 months, and a slow vital capacity ≥ 70% of normal. Patients were randomised (1:1:1) to aldesleukin 2 MIU, 1 MIU, or placebo once daily for 5 days every 4 weeks for 3 cycles. Primary outcome was change from baseline in Treg percentage of CD4+ T cells (%Tregs) following a first cycle. Secondary laboratory outcomes included: %Treg and Treg number following repeated cycles, and plasma CCL2 and neurofilament light chain protein (NFL) concentrations as surrogate markers of efficacy. Safety outcomes included motor-function (ALSFRS-R), slow vital capacity (SVC), and adverse event reports. This trial is registered with ClinicalTrials.gov, NCT02059759. Findings: All randomised patients (12 per group), recruited from October 2015 to December 2015, were alive at the end of follow-up and included in the intent-to-treat (ITT) analysis. No drug-related serious adverse event was observed. Non-serious adverse events occurred more frequently with the 1 and 2 MIU IL-2 doses compared to placebo, including injection site reactions and flu-like symptoms. Primary outcome analysis showed a significant increase (p < 0·0001) in %Tregs in the 2 MIU and 1 MIU arms (mean [SD]: 2 MIU: +6·2% [2·2]; 1 MIU: +3·9% [1·2]) as compared to placebo (mean [SD]: -0·49% [1·3]). Effect sizes (ES) were large in treated groups: 2 MIU ES=3·7 (IC95%: 2·3–4·9) and 1 MIU ES=3·5 (IC95%: 2·1–4·6). Secondary outcomes showed a significant increase in %Tregs following repeated cycles (p < 0·0001) as compared to placebo, and a dose-dependent decrease in plasma CCL2 (p = 0·0049). There were no significant differences amongst the three groups on plasma NFL levels. Interpretation: Ld-IL-2 is well tolerated and immunologically effective in subjects with ALS. These results warrant further investigation into their eventual therapeutic impact on slowing ALS disease progression. Funding: : The French Health Ministry (PHRC-I-14-056), EU H2020 (grant #633413), and the Association pour la Recherche sur la SLA (ARSLA). © 2020 The Authors
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32.
  • Chadalavada, Ravi Teja, 1989-, et al. (författare)
  • Bi-directional navigation intent communication using spatial augmented reality and eye-tracking glasses for improved safety in human-robot interaction
  • 2020
  • Ingår i: Robotics and Computer-Integrated Manufacturing. - : Elsevier. - 0736-5845 .- 1879-2537. ; 61
  • Tidskriftsartikel (refereegranskat)abstract
    • Safety, legibility and efficiency are essential for autonomous mobile robots that interact with humans. A key factor in this respect is bi-directional communication of navigation intent, which we focus on in this article with a particular view on industrial logistic applications. In the direction robot-to-human, we study how a robot can communicate its navigation intent using Spatial Augmented Reality (SAR) such that humans can intuitively understand the robot's intention and feel safe in the vicinity of robots. We conducted experiments with an autonomous forklift that projects various patterns on the shared floor space to convey its navigation intentions. We analyzed trajectories and eye gaze patterns of humans while interacting with an autonomous forklift and carried out stimulated recall interviews (SRI) in order to identify desirable features for projection of robot intentions. In the direction human-to-robot, we argue that robots in human co-habited environments need human-aware task and motion planning to support safety and efficiency, ideally responding to people's motion intentions as soon as they can be inferred from human cues. Eye gaze can convey information about intentions beyond what can be inferred from the trajectory and head pose of a person. Hence, we propose eye-tracking glasses as safety equipment in industrial environments shared by humans and robots. In this work, we investigate the possibility of human-to-robot implicit intention transference solely from eye gaze data and evaluate how the observed eye gaze patterns of the participants relate to their navigation decisions. We again analyzed trajectories and eye gaze patterns of humans while interacting with an autonomous forklift for clues that could reveal direction intent. Our analysis shows that people primarily gazed on that side of the robot they ultimately decided to pass by. We discuss implications of these results and relate to a control approach that uses human gaze for early obstacle avoidance.
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33.
  • Cullen, Nicholas C., et al. (författare)
  • Comparing progression biomarkers in clinical trials of early Alzheimer's disease
  • 2020
  • Ingår i: Annals of Clinical and Translational Neurology. - : Wiley. - 2328-9503. ; 7:9, s. 1661-1673
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: To investigate the statistical power of plasma, imaging, and cognition biomarkers as Alzheimer's disease (AD) clinical trial outcome measures. Methods: Plasma neurofilament light, structural magnetic resonance imaging, and cognition were measured longitudinally in the Alzheimer's Disease Neuroimaging Initiative (ADNI) in control (amyloid PET or CSF A beta 42 negative [A beta-] with Clinical Dementia Rating scale [CDR] = 0; n = 330), preclinical AD (A beta + with CDR = 0; n = 218) and mild AD (A beta + with CDR = 0.5-1; n = 697) individuals. A statistical power analysis was performed across biomarkers and groups based on longitudinal mixed effects modeling and using several different clinical trial designs. Results: For a 30-month trial of preclinical AD, both the temporal composite and hippocampal volumes were superior to plasma neurofilament light and cognition. For an 18-month trial of mild AD, hippocampal volume was superior to all other biomarkers. Plasma neurofilament light became more effective with increased trial duration or sampling frequency. Imaging biomarkers were characterized by high slope and low within-subject variability, while plasma neurofilament light and cognition were characterized by higher within-subject variability. Interpretation: MRI measures had properties that made them preferable to cognition and pNFL as outcome measures in clinical trials of early AD, regardless of cognitive status. However, pNfL and cognition can still be effective depending on inclusion criteria, sampling frequency, and response to therapy. Future trials will help to understand how sensitive pNfL and MRI are to detect downstream effects on neurodegeneration of drugs targeting amyloid and tau pathology in AD.
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34.
  • Dutkiewicz, Robert, et al. (författare)
  • Dementia and CSF-biomarkers for Alzheimer's disease predict mortality after acute hip fracture
  • 2020
  • Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 64:1, s. 93-103
  • Tidskriftsartikel (refereegranskat)abstract
    • Background Mortality is high after an acute hip fracture (AHF) surgery. Are cognitive impairment and/or altered levels of Alzheimer's Disease (AD)-biomarkers in cerebrospinal fluid (CSF) predictors of mortality in AHF-patients, as retrospective studies indicate? Methods Prospective single-center study including 373 AHF-patients, operated in spinal anesthesia. Cognitive status was evaluated by clinical dementia rating (CDR); CSF was analyzed for AD-biomarker concentrations (total tau (T-tau), phosphorylated tau (P-tau), amyloid beta ratio (A beta 42/A beta 40). CDR and biomarker levels were related to mortality up to one-year post-surgery, using univariate logistic regression analysis. Results Survival analyses showed that mortality was associated to the degree of dementia. In the entire patient cohort 30-, 90-, and 365-day mortality rates were 7.2%, 15.5%, and 25.5%, respectively, but only 2.7%, 5.5%, and 12.6%, for cognitively intact vs 16.3%, 31.7%, and 42.3% for demented patients (OR = 2.2-2.8 [CI = 1.6-4.9]; P = .0001). High CSF T-tau (OR = 1.19 [CI = 1.05-1.33]; P = .004) and low A beta 42/A beta 40-ratio (OR = 0.85 [CI = 0.74-0.97]; P = .017) were associated with increased 90-day mortality. Analysis of 4 subgroups (Cognitive impairment +/- and Biomarkers +/-) showed significant associations of dementia and CSF biomarker concentrations to mortality after an AHF. Even cognitively intact patients presenting with abnormal AD-biomarkers showed an increased 90-day mortality which, however, was statistically insignificant. Conclusions Cognitive impairment and altered CSF biomarker concentrations indicative of AD pathology can predict increased mortality in patients with an AHF, and so probably even before clinical dementia diagnosis by early biomarker analysis; a notion that may have substantial clinical implications by improving perioperative treatment and postoperative rehabilitation.
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35.
  • Enblom, Anneli, et al. (författare)
  • Erythrocytosis, thrombocytosis, and rate of recurrent thromboembolic event : a population based cohort study
  • 2023
  • Ingår i: European Journal of Haematology. - : John Wiley & Sons. - 0902-4441 .- 1600-0609. ; 110:6, s. 608-617
  • Tidskriftsartikel (refereegranskat)abstract
    • Introduction: The management to reduce risk of thromboembolic complications in polycythemia vera and essential thrombocythemia are well established, but for other conditions with elevated hemoglobin, hematocrit, or platelets there are no consensus regarding treatment and follow up.Aims: To assess frequency of elevated blood values in patients with thromboembolic event, how many of these should be investigated further regarding myeloproliferative neoplasm and if the risk of recurrent event is depending on underlying condition.Methods: Retrospective cohort study of 3931 adult patients in the county of Norrbotten, Sweden, with thromboembolism during 2017 and 2018.Results: Of the 3931 patients, 1195 had either elevated Hb, HCT, or platelets fulfilling the 2016 revised WHO criteria for PV and ET, and out of these 411 should be evaluated regarding underlying myeloproliferative neoplasms. Unexplained thrombocytosis and secondary erythrocytosis were associated with the highest rate of recurrent event as well as the most inferior restricted mean survival time.Conclusion: Elevated blood values are common in patients with thromboembolic event and the high risk of recurrent event and inferior restricted mean survival time in patients with unexplained thrombocytosis and secondary erythrocytosis implicates the importance of finding and managing the underlying condition.
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36.
  • Erickson, Pontus, et al. (författare)
  • Prevalence and Clinical Implications of a β-Amyloid-Negative, Tau-Positive Cerebrospinal Fluid Biomarker Profile in Alzheimer Disease.
  • 2023
  • Ingår i: JAMA neurology. - 2168-6157. ; 80:9, s. 969-979
  • Tidskriftsartikel (refereegranskat)abstract
    • Knowledge is lacking on the prevalence and prognosis of individuals with a β-amyloid-negative, tau-positive (A-T+) cerebrospinal fluid (CSF) biomarker profile.To estimate the prevalence of a CSF A-T+ biomarker profile and investigate its clinical implications.This was a retrospective cohort study of the cross-sectional multicenter University of Gothenburg (UGOT) cohort (November 2019-January 2021), the longitudinal multicenter Alzheimer Disease Neuroimaging Initiative (ADNI) cohort (individuals with mild cognitive impairment [MCI] and no cognitive impairment; September 2005-May 2022), and 2 Wisconsin cohorts, Wisconsin Alzheimer Disease Research Center and Wisconsin Registry for Alzheimer Prevention (WISC; individuals without cognitive impairment; February 2007-November 2020). This was a multicenter study, with data collected from referral centers in clinical routine (UGOT) and research settings (ADNI and WISC). Eligible individuals had 1 lumbar puncture (all cohorts), 2 or more cognitive assessments (ADNI and WISC), and imaging (ADNI only) performed on 2 separate occasions. Data were analyzed on August 2022 to April 2023.Baseline CSF Aβ42/40 and phosphorylated tau (p-tau)181; cognitive tests (ADNI: modified preclinical Alzheimer cognitive composite [mPACC]; WISC: modified 3-test PACC [PACC-3]). Exposures in the ADNI cohort included [18F]-florbetapir amyloid positron emission tomography (PET), magnetic resonance imaging (MRI), [18F]-fluorodeoxyglucose PET (FDG-PET), and cross-sectional tau-PET (ADNI: [18F]-flortaucipir, WISC: [18F]-MK6240).Primary outcomes were the prevalence of CSF AT biomarker profiles and continuous longitudinal global cognitive outcome and imaging biomarker trajectories in A-T+ vs A-T- groups. Secondary outcomes included cross-sectional tau-PET.A total of 7679 individuals (mean [SD] age, 71.0 [8.4] years; 4101 male [53%]) were included in the UGOT cohort, 970 individuals (mean [SD] age, 73 [7.0] years; 526 male [54%]) were included in the ADNI cohort, and 519 individuals (mean [SD] age, 60 [7.3] years; 346 female [67%]) were included in the WISC cohort. The prevalence of an A-T+ profile in the UGOT cohort was 4.1% (95% CI, 3.7%-4.6%), being less common than the other patterns. Longitudinally, no significant differences in rates of worsening were observed between A-T+ and A-T- profiles for cognition or imaging biomarkers. Cross-sectionally, A-T+ had similar tau-PET uptake to individuals with an A-T- biomarker profile.Results suggest that the CSF A-T+ biomarker profile was found inapproximately5% of lumbar punctures and was not associated with a higher rate of cognitive decline or biomarker signs of disease progression compared with biomarker-negative individuals.
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37.
  • Fernandes Gomes, Bárbara, et al. (författare)
  • α-Synuclein seed amplification assay as a diagnostic tool for parkinsonian disorders.
  • 2023
  • Ingår i: Parkinsonism & related disorders. - 1873-5126. ; 117
  • Tidskriftsartikel (refereegranskat)abstract
    • Synucleinopathies such as Parkinson's disease (PD) and multiple system atrophy (MSA) can be challenging to diagnose due to the symptom overlap with, for example, atypical parkinsonisms like progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). Seed amplification assays (SAA), developed for the detection of α-synuclein (αSyn) aggregates in CSF, have been successful when used as a biomarker evaluation for synucleinopathies. In this study, we investigated the potential of this assay to not only detect αSyn seeds in CSF, but also discriminate between movement disorders.The αSyn-SAA was tested in a Scandinavian cohort composed of 129 CSF samples from patients with PD (n=55), MSA (n=27), CBD (n=7), and PSP (n=16), as well as healthy controls (HC, n=24).The αSyn seed amplification assay (αSyn-SAA) was able to correctly identify all PD samples as positive (sensitivity of 100%) while also discriminating the PD group from HC (70.8% specificity, p<0.0001) and tauopathies [CBD (71% specificity) and PSP (75% specificity), p<0.0001)]. The αSyn-SAA was also able to identify almost all MSA samples as positive for αSyn aggregation (sensitivity of 92.6%). In general, this assay is able to discriminate between the synucleinopathies and tauopathies analyzed herein (p<0.0001) despite the overlapping symptoms in these diseases.These findings suggest the αSyn-SAA is a useful diagnostic tool for differentiating between different parkinsonian disorders, although further optimization may be needed.
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38.
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39.
  • Forte, Paolo, 1995-, et al. (författare)
  • Online Task Assignment and Coordination in Multi-Robot Fleets
  • 2021
  • Ingår i: IEEE Robotics and Automation Letters. - : IEEE Press. - 2377-3766. ; 6:3, s. 4584-4591
  • Tidskriftsartikel (refereegranskat)abstract
    • We propose a loosely-coupled framework for integrated task assignment, motion planning, coordination and contro of heterogeneous fleets of robots subject to non-cooperative tasks. The approach accounts for the important real-world requiremen that tasks can be posted asynchronously. We exploit systematic search for optimal task assignment, where interference is considered as a cost and estimated with knowledge of the kinodynamic models and current state of the robots. Safety is guaranteed by an online coordination algorithm, where the absence of collisions is treated as a hard constraint. The relation between the weight of interference cost in task assignment and computational overhead is analyzed empirically, and the approach is compared against alternative realizations using local search algorithms for task assignment.
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40.
  • Franke, Ulrik, 1981-, et al. (författare)
  • Cyber situational awareness issues and challenges
  • 2022
  • Ingår i: Cybersecurity and Cognitive Science. - : Elsevier. - 9780323905701 - 9780323906968 ; , s. 235-265
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • Today, most enterprises are increasingly reliant on information technology to carry out their operations. This also entails an increasing need for cyber situational awareness—roughly, to know what is going on in the cyber domain, and thus be able to adequately respond to events such as attacks or accidents. This chapter argues that cyber situational awareness is best understood by combining three complementary points of view: the technological, the socio-cognitive, and the organizational perspectives. In addition, the chapter investigates the prospects for reasoning about adversarial actions. This part also reports on a small empirical investigation where participants in the Locked Shields cyber defense exercise were interviewed about their information needs with respect to threat actors. The chapter is concluded with a discussion regarding important challenges to be addressed along with suggestions for further research.
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41.
  • Giangrande, C., et al. (författare)
  • Harmonization and standardization of biofluid-based biomarker measurements for AT(N) classification in Alzheimer's disease
  • 2023
  • Ingår i: Alzheimer's and Dementia: Diagnosis, Assessment and Disease Monitoring. - 2352-8729. ; 15:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Fluid biomarkers are currently measured in cerebrospinal fluid and blood for Alzheimer's disease diagnosis and are promising targets for drug development and for patients' follow-up in clinical trials. These biomarkers have been grouped in an unbiased research framework, the amyloid (A & beta;), tau, and neurodegeneration (AT[N]) biomarker system to aid patients' early diagnosis and stratification. Metrological approaches relying on mass spectrometry have been used for the development of reference materials and reference measurement procedures. Despite their excellent performances as clinical tools, fluid biomarkers often present an important between-laboratory variation. Standardization efforts were carried out on the biomarkers currently included in the AT(N) classification system, involving the collaboration of national metrology institutes, clinicians, researchers, and in vitro diagnostic providers. This article provides an overview of current activities towards standardization. These reference methods and reference materials may be used for recalibration of immunoassays and the establishment of standardized cutoff values allowing a better stratification of Alzheimer's disease patients. HighlightsThe AT(N) biomarker system allows stratifying AD patients on the basis of biomarker profiles.Fluid biomarker measurements often present an important between-laboratory variation preventing the establishment of standardized cutoff values.Overview on the standardization initiatives involving the fluid biomarkers currently included in the AT(N) framework.
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42.
  • Giovannelli, Ilaria, et al. (författare)
  • Amyotrophic lateral sclerosis transcriptomics reveals immunological effects of low-dose interleukin-2.
  • 2021
  • Ingår i: Brain communications. - : Oxford University Press (OUP). - 2632-1297. ; 3:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Amyotrophic lateral sclerosis is a fatal neurodegenerative disease causing upper and lower motor neuron loss and currently no effective disease-modifying treatment is available. A pathological feature of this disease is neuroinflammation, a mechanism which involves both CNS-resident and peripheral immune system cells. Regulatory T-cells are immune-suppressive agents known to be dramatically and progressively decreased in patients with amyotrophic lateral sclerosis. Low-dose interleukin-2 promotes regulatory T-cell expansion and was proposed as an immune-modulatory strategy for this disease. A randomized placebo-controlled pilot phase-II clinical trial called Immuno-Modulation in Amyotrophic Lateral Sclerosis was carried out to test safety and activity of low-dose interleukin-2 in 36 amyotrophic lateral sclerosis patients (NCT02059759). Participants were randomized to 1MIU, 2MIU-low-dose interleukin-2 or placebo and underwent one injection daily for 5 days every 28 days for three cycles. In this report, we describe the results of microarray gene expression profiling of trial participants' leukocyte population. We identified a dose-dependent increase in regulatory T-cell markers at the end of the treatment period. Longitudinal analysis revealed an alteration and inhibition of inflammatory pathways occurring promptly at the end of the first treatment cycle. These responses are less pronounced following the end of the third treatment cycle, although an activation of immune-regulatory pathways, involving regulatory T-cells and T helper 2 cells, was evident only after the last cycle. This indicates a cumulative effect of repeated low-dose interleukin-2 administration on regulatory T-cells. Our analysis suggested the existence of inter-individual variation amongst trial participants and we therefore classified patients into low, moderate and high-regulatory T-cell-responders. NanoString profiling revealed substantial baseline differences between participant immunological transcript expression profiles with the least responsive patients showing a more inflammatory-prone phenotype at the beginning of the trial. Finally, we identified two genes in which pre-treatment expression levels correlated with the magnitude of drug responsiveness. Therefore, we proposed a two-biomarker based regression model able to predict patient regulatory T-cell-response to low-dose interleukin-2. These findings and the application of this methodology could be particularly relevant for future precision medicine approaches to treat amyotrophic lateral sclerosis.
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43.
  • Gobom, Johan, et al. (författare)
  • Validation of the LUMIPULSE automated immunoassay for the measurement of core AD biomarkers in cerebrospinal fluid.
  • 2022
  • Ingår i: Clinical chemistry and laboratory medicine. - : Walter de Gruyter GmbH. - 1437-4331 .- 1434-6621. ; 60:2, s. 207-219
  • Tidskriftsartikel (refereegranskat)abstract
    • The core cerebrospinal fluid (CSF) biomarkers; total tau (tTau), phospho-tau (pTau), amyloid β1-42(Aβ 1-42), and the Aβ 1-42/Aβ 1-40 ratio have transformed Alzheimer's disease (AD) research and are today increasingly used in clinical routine laboratories as diagnostic tools. Fully automated immunoassay instruments with ready-to-use assay kits and calibrators has simplified their analysis and improved reproducibility of measurements. We evaluated the analytical performance of the fully automated immunoassay instrument LUMIPULSE G (Fujirebio) for measurement of the four core AD CSF biomarkers and determined cutpoints for AD diagnosis.Comparison of the LUMIPULSE G assays was performed with the established INNOTEST ELISAs (Fujirebio) for hTau Ag, pTau 181, β-amyloid 1-42, and with V-PLEX Plus Aβ Peptide Panel 1 (6E10) (Meso Scale Discovery) for Aβ 1-42/Aβ 1-40, as well as with a LC-MS reference method for Aβ 1-42. Intra- and inter-laboratory reproducibility was evaluated for all assays. Clinical cutpoints for Aβ 1-42, tTau, and pTau was determined by analysis of three cohorts of clinically diagnosed patients, comprising 651 CSF samples. For the Aβ 1-42/Aβ 1-40 ratio, the cutpoint was determined by mixture model analysis of 2,782 CSF samples.The LUMIPULSE G assays showed strong correlation to all other immunoassays (r>0.93 for all assays). The repeatability (intra-laboratory) CVs ranged between 2.0 and 5.6%, with the highest variation observed for β-amyloid 1-40. The reproducibility (inter-laboratory) CVs ranged between 2.1 and 6.5%, with the highest variation observed for β-amyloid 1-42. The clinical cutpoints for AD were determined to be 409ng/L for total tau, 50.2ng/L for pTau 181, 526ng/L for β-amyloid 1-42, and 0.072 for the Aβ 1-42/Aβ 1-40 ratio.Our results suggest that the LUMIPULSE G assays for the CSF AD biomarkers are fit for purpose in clinical laboratory practice. Further, they corroborate earlier presented reference limits for the biomarkers.
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44.
  • Gray, E., et al. (författare)
  • A multi-center study of neurofilament assay reliability and inter-laboratory variability
  • 2020
  • Ingår i: Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration. - : Informa UK Limited. - 2167-8421 .- 2167-9223. ; 21:5-6, s. 452-458
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: Significantly elevated levels of neurofilament light chain (NfL) and phosphorylated neurofilament heavy chain (pNfH) have been described in the blood and cerebrospinal fluid (CSF) of amyotrophic lateral sclerosis (ALS) patients. The aim of this study was to evaluate the analytical performance of different neurofilament assays in a round robin with 10 centers across Europe/U.S.Methods: Serum, plasma and CSF samples from a group of five ALS and five neurological control patients were distributed across 10 international specialist neurochemical laboratories for analysis by a range of commercial and in-house neurofilament assays. The performance of all assays was evaluated for their ability to differentiate between the groups. The inter-assay coefficient of variation was calculated where appropriate from sample measurements performed across multiple laboratories using the same assay.Results:All assays could differentiate ALS patients from controls in CSF. Inter-assay coefficient of variation of analytical platforms performed across multiple laboratories varied between 6.5% and 41.9%.Conclusions:This study is encouraging for the growing momentum toward integration of neurofilament measurement into the specialized ALS clinic. It demonstrates the importance of 'round robin' studies necessary to ensure the analytical quality required for translation to the routine clinical setting. A standardized neurofilament probe is needed which can be used as international benchmark for analytical performance in ALS.
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45.
  • Gupta, Himanshu, 1993-, et al. (författare)
  • NDT-6D for color registration in agri-robotic applications
  • 2023
  • Ingår i: Journal of Field Robotics. - : John Wiley & Sons. - 1556-4959 .- 1556-4967. ; 40:6, s. 1603-1619
  • Tidskriftsartikel (refereegranskat)abstract
    • Registration of point cloud data containing both depth and color information is critical for a variety of applications, including in-field robotic plant manipulation, crop growth modeling, and autonomous navigation. However, current state-of-the-art registration methods often fail in challenging agricultural field conditions due to factors such as occlusions, plant density, and variable illumination. To address these issues, we propose the NDT-6D registration method, which is a color-based variation of the Normal Distribution Transform (NDT) registration approach for point clouds. Our method computes correspondences between pointclouds using both geometric and color information and minimizes the distance between these correspondences using only the three-dimensional (3D) geometric dimensions. We evaluate the method using the GRAPES3D data set collected with a commercial-grade RGB-D sensor mounted on a mobile platform in a vineyard. Results show that registration methods that only rely on depth information fail to provide quality registration for the tested data set. The proposed color-based variation outperforms state-of-the-art methods with a root mean square error (RMSE) of 1.1-1.6 cm for NDT-6D compared with 1.1 - 2.3 cm for other color-information-based methods and 1.2 - 13.7 cm for noncolor-information-based methods. The proposed method is shown to be robust against noises using the TUM RGBD data set by artificially adding noise present in an outdoor scenario. The relative pose error (RPE) increased 14% for our method compared to an increase of 75% for the best-performing registration method. The obtained average accuracy suggests that the NDT-6D registration methods can be used for in-field precision agriculture applications, for example, crop detection, size-based maturity estimation, and growth modeling.
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46.
  • Gupta, Himanshu, 1993-, et al. (författare)
  • Revisiting Distribution-Based Registration Methods
  • 2023
  • Ingår i: 2023 European Conference on Mobile Robots (ECMR). - : IEEE. - 9798350307047 - 9798350307054 ; , s. 43-48
  • Konferensbidrag (refereegranskat)abstract
    • Normal Distribution Transformation (NDT) registration is a fast, learning-free point cloud registration algorithm that works well in diverse environments. It uses the compact NDT representation to represent point clouds or maps as a spatial probability function that models the occupancy likelihood in an environment. However, because of the grid discretization in NDT maps, the global minima of the registration cost function do not always correlate to ground truth, particularly for rotational alignment. In this study, we examined the NDT registration cost function in-depth. We evaluated three modifications (Student-t likelihood function, inflated covariance/heavily broadened likelihood curve, and overlapping grid cells) that aim to reduce the negative impact of discretization in classical NDT registration. The first NDT modification improves likelihood estimates for matching the distributions of small population sizes; the second modification reduces discretization artifacts by broadening the likelihood tails through covariance inflation; and the third modification achieves continuity by creating the NDT representations with overlapping grid cells (without increasing the total number of cells). We used the Pomerleau Dataset evaluation protocol for our experiments and found significant improvements compared to the classic NDT D2D registration approach (27.7% success rate) using the registration cost functions "heavily broadened likelihood NDT" (HBL-NDT) (34.7% success rate) and "overlapping grid cells NDT" (OGC-NDT) (33.5% success rate). However, we could not observe a consistent improvement using the Student-t likelihood-based registration cost function (22.2% success rate) over the NDT P2D registration cost function (23.7% success rate). A comparative analysis with other state-of-art registration algorithms is also presented in this work. We found that HBL-NDT worked best for easy initial pose difficulties scenarios making it suitable for consecutive point cloud registration in SLAM application.
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47.
  • Gupta, Himanshu, 1993-, et al. (författare)
  • Robust scan registration for navigation in forest environment using low-resolution LiDAR sensors
  • 2023
  • Ingår i: Sensors. - : MDPI. - 1424-8220. ; 23:10
  • Tidskriftsartikel (refereegranskat)abstract
    • Automated forest machines are becoming important due to human operators’ complex and dangerous working conditions, leading to a labor shortage. This study proposes a new method for robust SLAM and tree mapping using low-resolution LiDAR sensors in forestry conditions. Our method relies on tree detection to perform scan registration and pose correction using only low-resolution LiDAR sensors (16Ch, 32Ch) or narrow field of view Solid State LiDARs without additional sensory modalities like GPS or IMU. We evaluate our approach on three datasets, including two private and one public dataset, and demonstrate improved navigation accuracy, scan registration, tree localization, and tree diameter estimation compared to current approaches in forestry machine automation. Our results show that the proposed method yields robust scan registration using detected trees, outperforming generalized feature-based registration algorithms like Fast Point Feature Histogram, with an above 3 m reduction in RMSE for the 16Chanel LiDAR sensor. For Solid-State LiDAR the algorithm achieves a similar RMSE of 3.7 m. Additionally, our adaptive pre-processing and heuristic approach to tree detection increased the number of detected trees by 13% compared to the current approach of using fixed radius search parameters for pre-processing. Our automated tree trunk diameter estimation method yields a mean absolute error of 4.3 cm (RSME = 6.5 cm) for the local map and complete trajectory maps.
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48.
  • Hang, Trieu, et al. (författare)
  • Natural surface floaters in image-based river surface velocimetry: Insights from a case study
  • 2024
  • Ingår i: Flow Measurement and Instrumentation. - : Elsevier. - 0955-5986 .- 1873-6998. ; 96
  • Tidskriftsartikel (refereegranskat)abstract
    • This study focuses on utilizing image techniques for river velocity measurement, with a specific emphasis onnatural surface floating patterns. Employing a multi-camera system, we conducted 3D measurements on riversurfaces, including surface velocity and water surface reconstruction. A pattern-based tracking approach hasbeen adopted to improve the performance of image measurements on different types of natural floating tracers.The study employs the following approaches: 3D Lagrangian Pattern Tracking Velocimetry (3D-LPTV), 2DLagrangian Pattern Velocimetry (2D- LPTV), and Large-scale Particle Image Velocimetry (LSPIV), for surfacevelocity estimation. The outcomes revealed that all three approaches yielded consistent results in terms ofaveraged velocity. However, the LSPIV method produced about two times higher uncertainty in measured velocitiescompared to the other methods. A strategy to assess the quality of river surface patterns in velocityestimation is presented. Specifically, the sum of squared interrogation area intensity gradient (SSIAIG) was foundto be strongly correlated with measurement uncertainty. Additionally, a term related to the peak sidelobe ratio(PSR) of the cross-correlation map was found as an effective constraint, ensuring the image-tracking processachieves high reliability. The precision of measurements increases corresponding to the increase of image intensitygradient and PSR.
  •  
49.
  • Hang, Trieu, et al. (författare)
  • Photogrammetry for Free Surface Flow Velocity Measurement : From Laboratory to Field Measurements
  • 2021
  • Ingår i: Water. - : MDPI. - 2073-4441. ; 13:12
  • Tidskriftsartikel (refereegranskat)abstract
    • This study describes a multi-camera photogrammetric approach to measure the 3D velocityof free surface flow. The properties of the camera system and particle tracking velocimetry (PTV)algorithm were first investigated in a measurement of a laboratory open channel flow to prepare forfield measurements. The in situ camera calibration methods corresponding to the two measurementsituations were applied to mitigate the instability of the camera mechanism and camera geometry.There are two photogrammetry-based PTV algorithms presented in this study regarding differenttypes of surface particles employed on the water flow. While the first algorithm uses the particletracking method applied for individual particles, the second algorithm is based on correlation-basedparticle clustering tracking applied for clusters of small size particles. In the laboratory, referencedata are provided by particle image velocimetry (PIV) and laser Doppler velocimetry (LDV). Thedifferences in velocities measured by photogrammetry and PIV, photogrammetry and LDV are 0.1%and 3.6%, respectively. At a natural river, the change of discharges between two measurement timesis found to be 15%, and the corresponding value reported regarding mass flow through a nearbyhydropower plant is 20%. The outcomes reveal that the method can provide a reliable estimation of3D surface velocity with sufficient accuracy.
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50.
  • Hilger, Maximilian, 1998-, et al. (författare)
  • Towards introspective loop closure in 4D radar SLAM
  • 2024
  • Konferensbidrag (refereegranskat)abstract
    • Imaging radar is an emerging sensor modality in the context of Localization and Mapping (SLAM), especially suitable for vision-obstructed environments. This article investigates the use of 4D imaging radars for SLAM and analyzes the challenges in robust loop closure. Previous work indicates that 4D radars, together with inertial measurements, offer ample information for accurate odometry estimation. However, the low field of view, limited resolution, and sparse and noisy measurements render loop closure a significantly more challenging problem. Our work builds on the previous work - TBV SLAM - which was proposed for robust loop closure with 360∘ spinning radars. This article highlights and addresses challenges inherited from a directional 4D radar, such as sparsity, noise, and reduced field of view, and discusses why the common definition of a loop closure is unsuitable. By combining multiple quality measures for accurate loop closure detection adapted to 4D radar data, significant results in trajectory estimation are achieved; the absolute trajectory error is as low as 0.46 m over a distance of 1.8 km, with consistent operation over multiple environments. 
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