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Sökning: WFRF:(Pettersson Erik) > Linköpings universitet

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1.
  • Adolfsson, Jan, et al. (författare)
  • Clinical characteristics and primary treatment of prostate cancer in Sweden between 1996 and 2005
  • 2007
  • Ingår i: Scandinavian Journal of Urology and Nephrology. - : Informa UK Limited. - 0036-5599 .- 1651-2065. ; 41:6, s. 456-477
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: The incidence of prostate cancer is rising rapidly in Sweden and there is a need to better understand the pattern of diagnosis, tumor characteristics and treatment. MATERIAL AND METHODS: Between 1996 and 2005, all new cases of adenocarcinoma of the prostate gland were intended to be registered in the National Prostate Cancer Register (NPCR). This register contains information on diagnosing unit, date of diagnosis, cause of diagnosis, tumor grade, tumor stage according to the TNM classification in force, serum prostate-specific antigen (PSA) levels at diagnosis and primary treatment given within the first 6 months after diagnosis. RESULTS: In total, 72,028 patients were registered, comprising >97% of all pertinent incident cases of prostate cancer in the Swedish Cancer Register (SCR). During the study period there was a considerable decrease in median age at the time of diagnosis, a stage migration towards smaller tumors, a decrease in median serum PSA values at diagnosis, a decrease in the age-standardized incidence rate of men diagnosed with distant metastases or with a PSA level of > 100 ng/ml at diagnosis and an increase in the proportion of tumors with Gleason score <6. Relatively large geographical differences in the median age at diagnosis and the age-standardized incidence of cases with category T1c tumors were observed. Treatment with curative intent increased dramatically and treatment patterns varied according to geographical region. In men with localized tumors and a PSA level of <20 ng/ml at diagnosis, expectant treatment was more commonly used in those aged > or =75 years than in those aged <75 years. Also, the pattern of endocrine treatment varied in different parts of Sweden. CONCLUSIONS: All changes in the register seen over time are consistent with increased diagnostic activity, especially PSA testing, resulting in an increased number of cases with early disease, predominantly tumors in category T1c. The patterns of diagnosis and treatment of prostate cancer vary considerably in different parts of Sweden. The NPCR continues to be an important source for research, epidemiological surveillance of the incidence, diagnosis and treatment of prostate cancer.
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2.
  • Bergemalm, Daniel, 1977-, et al. (författare)
  • Systemic Inflammation in Preclinical Ulcerative Colitis
  • 2021
  • Ingår i: Gastroenterology. - : AGA Institute. - 0016-5085 .- 1528-0012. ; 161:5, s. 1526-1539.e9
  • Tidskriftsartikel (refereegranskat)abstract
    • Background & Aims: Preclinical ulcerative colitis is poorly defined. We aimed to characterize the preclinical systemic inflammation in ulcerative colitis, using a comprehensive set of proteins.Methods: We obtained plasma samples biobanked from individuals who developed ulcerative colitis later in life (n = 72) and matched healthy controls (n = 140) within a population-based screening cohort. We measured 92 proteins related to inflammation using a proximity extension assay. The biologic relevance of these findings was validated in an inception cohort of patients with ulcerative colitis (n = 101) and healthy controls (n = 50). To examine the influence of genetic and environmental factors on these markers, a cohort of healthy twin siblings of patients with ulcerative colitis (n = 41) and matched healthy controls (n = 37) were explored.Results: Six proteins (MMP10, CXCL9, CCL11, SLAMF1, CXCL11 and MCP-1) were up-regulated (P < .05) in preclinical ulcerative colitis compared with controls based on both univariate and multivariable models. Ingenuity Pathway Analyses identified several potential key regulators, including interleukin-1β, tumor necrosis factor, interferon-gamma, oncostatin M, nuclear factor-κB, interleukin-6, and interleukin-4. For validation, we built a multivariable model to predict disease in the inception cohort. The model discriminated treatment-naïve patients with ulcerative colitis from controls with leave-one-out cross-validation (area under the curve = 0.92). Consistently, MMP10, CXCL9, CXCL11, and MCP-1, but not CCL11 and SLAMF1, were significantly up-regulated among the healthy twin siblings, even though their relative abundances seemed higher in incident ulcerative colitis.Conclusions: A set of inflammatory proteins are up-regulated several years before a diagnosis of ulcerative colitis. These proteins were highly predictive of an ulcerative colitis diagnosis, and some seemed to be up-regulated already at exposure to genetic and environmental risk factors.
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3.
  • Höglund, Linda, 1974-, et al. (författare)
  • Energy level scheme of InAs/InxGa1-xAs/GaAs quantum-dots-in-a-well infrared photodetector structures
  • 2010
  • Ingår i: Physical Review B. Condensed Matter and Materials Physics. - Woodbury, NY : American Physical Society. - 1098-0121 .- 1550-235X. ; 82:3, s. 035314-
  • Tidskriftsartikel (refereegranskat)abstract
    • A thorough investigation of quantum-dots-in-a-well structures for infrared photodetector applications has been performed employing different experimental techniques. The electronic structure of self-assembled InAs quantum dots embedded in an In0.15Ga0.85As/GaAs quantum well (QW) was deduced from photoluminescence (PL) and PL excitation (PLE) spectroscopy. From polarization-dependent PL it was revealed that the quantum dots hold two electron energy levels and two heavy-hole levels. Tunnel capacitance spectroscopy confirmed an electron energy level separation of about 50 meV, and additionally, that the conduction-band ground state and excited state of the dots are twofold and fourfold degenerates, respectively. Intersubband photocurrent spectroscopy, combined with simultaneous interband pumping of the dots, revealed a dominant transition at 150 meV (8.5 mu m) between the ground state of the quantum dots and the excited state of the QW. Results from detailed full three-dimensional calculations of the electronic structure, including effects of composition intermixing and interdot interactions, confirm the experimentally unravelled energy level scheme of the dots and well.
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4.
  • Jakobsson, Erik, et al. (författare)
  • Automated Usage Characterization of Mining Vehicles For Life Time Prediction
  • 2020
  • Ingår i: IFAC PAPERSONLINE. - : ELSEVIER. - 2405-8963. ; , s. 11950-11955
  • Konferensbidrag (refereegranskat)abstract
    • The life of a vehicle is heavily influenced by how it is used, and usage information is critical to predict the future condition of the machine. In this work we present a method to categorize what task an earthmoving vehicle is performing, based on a data driven model and a single standalone accelerometer. By training a convolutional neural network using a couple of weeks of labeled data, we show that a three axis accelerometer is sufficient to correctly classify between 5 different classes with an accuracy over 96% for a balanced dataset with no manual feature generation. The results are also compared against some other machine learning techniques, showing that the convolutional neural network has the highest performance, although other techniques are not far behind. An important conclusion is that methods and ideas from the area of Human Activity Recognition (HAR) are applicable also for vehicles. Copyright (C) 2020 The Authors.
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5.
  • Jakobsson, Erik, 1987-, et al. (författare)
  • Data driven modeling and estimation of accumulated damage in mining vehicles using on-board sensors
  • 2017
  • Ingår i: PHM 2017. Proceedings of the Annual Conference of the Prognostics and Health Management Society 2017, St. Petersburg, Florida, USA, October 2–5, 2017. - : Prognostics and Health Management Society. - 9781936263264 ; , s. 98-107
  • Konferensbidrag (refereegranskat)abstract
    • The life and condition of a MT65 mine truck frame is to a large extent related to how the machine is used. Damage from different stress cycles in the frame are accumulated over time, and measurements throughout the life of the machine are needed to monitor the condition. This results in high demands on the durability of sensors used. To make a monitoring system cheap and robust enough for a mining application, a small number of robust sensors are preferred rather than a multitude of local sensors such as strain gauges. The main question to be answered is whether a low number of robust on-board sensors can give the required information to recreate stress signals at various locations of the frame. Also the choice of sensors among many different locations and kinds are considered. A final question is whether the data could also be used to estimate road condition. By using accelerometer, gyroscope and strain gauge data from field tests of an Atlas Copco MT65 mine truck, coherence and Lasso-regression were evaluated as means to select which signals to use. ARX-models for stress estimation were created using the same data. By simulating stress signals using the models, rain flow counting and damage accumulation calculations were performed. The results showed that a low number of on-board sensors like accelerometers and gyroscopes could give enough information to recreate some of the stress signals measured. Together with a linear model, the estimated stress was accurate enough to evaluate the accumulated fatigue damage in a mining truck. The accumulated damage was also used to estimate the condition of the road on which the truck was traveling. To make a useful road monitoring system some more work is required, in particular regarding how vehicle speed influences damage accumulation.
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6.
  • Jakobsson, Erik, 1987- (författare)
  • Data-driven Condition Monitoring in Mining Vehicles
  • 2019
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Situation awareness is a crucial capability of any autonomous system, including mining vehicles such as drill rigs and mine trucks. Typically situation awareness is interpreted as the capability of an autonomous system to interpret its surroundings and the intentions of other agents. The internal system awareness however, is often not receiving the same focus, even though the success of any given mission is completely dependent of the condition of the agents themselves. The internal system awareness in the form of vehicle health is the focus of this thesis.As the mining industry becomes increasingly automated, and vehicles become increasingly advanced, the need for condition monitoring and prognostics will continue to rise. This thesis explores data-driven methods that estimate the health of mining vehicles to accommodate those needs. We do so by utilizing available sensor signals, common on a large amount of mining vehicles, to make assessments of the current vehicle condition and tasks. The mining industry is characterized by small series of highly specialized vehicles, which affects the possibility to use more traditional prognostic solutions.The resulting health information can be used both to aid in tasks such as maintenance planning, but also as an important input to decision making for the planning system, i.e. how to run the vehicle for minimum wear and damage, while maintaining other mission objectives.The contributions include: a) A method to use operational data to estimate damage on the frame of a mine truck. This is done using system identification to find a model describing stresses in the structure with input from other sensors such as accelerometers, load sensors and pressure sensors. The estimated stress time signal is in turn used to calculate accumulated damage, and is shown to reveal interesting conclusions on driver behavior. b) A method to characterize the different driving tasks by using an accelerometer and a convolutional neural network. We show that the model is capable of classifying the vehicle task correctly in 96 % of the cases. And finally c), a system for underground road monitoring, where a quarter car model and a Kalman filter are used to generate an estimate of the road profile, while positioning the vehicle using inertial measurements and access point signal strength.
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7.
  • Jakobsson, Erik, 1987-, et al. (författare)
  • Fatigue Damage Monitoring for Mining Vehicles using Data Driven Models
  • 2020
  • Ingår i: International Journal of Prognostics and Health Management. - Rochester, NY, United States : Prognostics and Health Management Society. - 2153-2648. ; 11:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The life and condition of a mine truck frame are related to how the machine is used. Damage from stress cycles is accumulated over time, and measurements throughout the life of the machine are needed to monitor the condition. This results in high demands on the durability of sensors, especially in a harsh mining application. To make a monitoring system cheap and robust, sensors already available on the vehicles are preferred rather than additional strain gauges. The main question in this work is whether the existing on-board sensors can give the required information to estimate stress signals and calculate accumulated damage of the frame. Model complexity requirements and sensors selection are also considered. A final question is whether the accumulated damage can be used for prognostics and to increase reliability. The investigation is performed using a large data set from two vehicles operating in real mine applications. Coherence analysis, ARX-models, and rain flow counting are techniques used. The results show that a low number of available on-board sensors like load cells, damper cylinder positions, and angle transducers can give enough information to recreate some of the stress signals measured. The models are also used to show significant differences in usage by different operators, and its effect on the accumulated damage.
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8.
  • Jakobsson, Erik, et al. (författare)
  • Fault Identification in Hydraulic Rock Drills from Indirect Measurement During Operation
  • 2021
  • Ingår i: IFAC PAPERSONLINE. - : ELSEVIER. - 2405-8963. ; , s. 73-78
  • Konferensbidrag (refereegranskat)abstract
    • This work presents a method for on-line condition monitoring of a hydraulic rock drill, though some of the findings can likely be applied in other applications. A fundamental difficulty for the rock drill application is discussed, namely the similarity between frequencies of internal standing waves and rock drill operation. This results in unpredictable pressure oscillations and superposition, which makes synchronization between measurement and model difficult. To overcome this, a data driven approach is proposed. The number and types of sensors are restricted due to harsh environmental conditions, and only operational data is available. Some faults are shown to be detectable using hand-crafted engineering features, with a direct physical connection to the fault of interest. Such features are easily interpreted and are shown to be robust against disturbances. Other faults are detected by classifying measured signals against a known reference. Dynamic Time Warping is shown to be an efficient way to measure similarity for cyclic signals with stochastic elements from disturbances, wave propagation and different durations, and also for cases with very small differences in measured pressure signals. Together, the two methods enables a step towards condition monitoring of a rock drill, robustly detecting very small changes in behaviour using a minimum amount of sensors. Copyright (C) 2021 The Authors.
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9.
  • Jakobsson, Erik, 1987-, et al. (författare)
  • Time Series Fault Classification for Wave Propagation Systems with Sparse Fault Data
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • In this work Time Series Classification techniques are investigated, and especially their applicability in applications where there are significant differences between the individuals where data is collected, and the individuals where the classification is evaluated. Classification methods are applied to a fault classification case, where a key assumption is that data from a fault free reference case for each specific individual is available. For the investigated application, wave propagation cause almost chaotic changes of a measured pressure signal, and physical modeling is difficult. Direct application of One-Nearest-Neighbor Dynamic Time Warping, a common technique for this kind of problem, and other machine learning techniques are shown to fail for this case and new methods to improve the situation are presented. By using relative features describing the difference from the reference case rather than the absolute time series, improvements are made compared to state-of-the-art time series classification algorithms.
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10.
  • Ahlstrand, Erik, 1974-, et al. (författare)
  • Highly Reduced Survival in Essential Thrombocythemia and Polycythemia Vera Patients with Vascular Complications during Follow-up
  • 2020
  • Ingår i: European Journal of Haematology. - : Munksgaard Forlag. - 0902-4441 .- 1600-0609. ; 104:3, s. 271-278
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: To explore the relative importance of risk factors, treatments and blood counts for the occurrence of vascular complications and their impact on life expectancy in Essential Thrombocythemia (ET) and Polycythemia Vera (PV).METHODS: Nested case-control study within the Swedish MPN registry. From a cohort of 922 ET patients and 763 PV patients, 71 ET and 81 PV cases with vascular complications were compared to matched controls.RESULTS: Incidence of vascular complications were 2.0 and 3.4 events per 100 patient-years in ET and PV, respectively. At diagnosis, no significant risk factor differences were observed between cases and controls in neither of the diseases. At the time of vascular event, ET complication cases did not differ significantly from controls but in PV, cases had significantly higher WBCs and were to a lesser extent treated with antithrombotic and cytoreductive therapy. Life expectancy was significantly decreased in both ET and PV cases compared to controls.CONCLUSIONS: The risk of vascular complications is high in both ET and PV and these complications have a considerable impact on life expectancy. The protective effect of antithrombotic and cytoreductive therapy for vascular complications in PV underscores the importance of avoiding undertreatment.
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