| 1. |
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| 2. |
- Andersson, Håkan, 1970-
(författare)
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A Co-Simulation Tool Applied to Hydraulic Percussion Units
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this dissertation, a co-simulation tool is presented that is meant to comprise a more comprehensive environment for modelling and simulation of hydraulic percussion units, which are used in hydraulic hammers and rock drills. These units generates the large impact forces, which are needed to demolish concrete structures in the construction industry or to fragment rock when drilling blast holes in mine drifting. This type of machinery is driven by fluid power and is by that dependent of coupled fluid-structure mechanisms for their operation. This tool consists of a 1D fluid system model, a 3D structural mechanic model and an interface to establish the fluid-structure couplings, which has in this work been applied to a hydraulic hammer. This approach will enable virtual prototyping during product development with an ambition to reduce the need for testing of physical prototypes, but also to facilitate more detailed studies of internal mechanisms. The tool has been implemented for two well-known simulation tools, and a co-simulation interface to enable communication between them has been devel-oped. The fluid system is simulated using the Hopsan simulation tool and the structural parts are simulated using the FE-simulation software LS-DYNA. The implementation of the co-simulation interface is based on the Functional Mock-up Interface standard in Hopsan and on the User Defined Feature module in LS-DYNA. The basic functions of the tool were first verified for a simple but relevant model comprising co-simulation of one component, and secondly co-simulation of two components were verified. These models were based on rigid body and linear elastic representation of the structural components. Further, it was experimentally validated using an existing hydraulic hammer product, where the responses from the experiments were compared to the corresponding simulated responses. To investigate the effects from a parameter change, the hammer was operated and simulated at four different running conditions. Dynamic simulation of the sealing gap, which is a fundamental mechanism used for controlling the percussive motion, was implemented to further enhance the simulated responses of the percussion unit. This implementation is based on a parametrisation of the deformed FE-model, where the gap height and the eccentric position are estimated from the deformed geometry in the sealing gap region, and then the parameters are sent to the fluid simulation for a more accurate calculation of the leakage flow. Wear in percussion units is an undesirable type of damage, which may cause significant reduction in performance or complete break-down, and today there are no methodology available to evaluate such damages on virtual prototypes. A method to study wear was developed using the co-simulation tool to simulate the fundamental behaviour of the percussion unit, and the wear routines in LS-DYNA were utilised for the calculation of wear.
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| 3. |
- Andersson, Håkan, et al.
(författare)
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Simulation of leakage flow through dynamic sealing gaps in hydraulic percussion units using a co-simulation approach
- 2021
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Ingår i: Simulation (San Diego, Calif.). - : Elsevier B.V.. - 1569-190X .- 1878-1462. ; 111
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a previously developed co-simulation method has been expanded to also simulate the dynamic behaviour of sealing gap regions in hydraulic percussion units. This approach is based on a 1D system model representing the fluid components and a 3D finite element model representing the structural parts of a hydraulic hammer. The sealing gap is a fundamental feature of a percussion unit, where the reciprocating motion of the piston is generated by the valve mechanism of the sealing gap. When the gap is closed it will prevent fluid flow between regions of different pressure levels. However, a small leakage flow through the gap will always occur which size depends on the clearance and the position of the piston. The method proposed here will take the structural motion and deformation into consideration when calculating the leakage flow. The deformed state of the structure is approximated by a cylindrical surface, in a least square manner, and communicated through the co-simulation interface to the fluid simulation module, and then used when calculating the leakage flow. This method aims at a more accurate simulation of the leakage flow that will not only yield a more realistic description of the mechanism on the local level, but also a more accurate estimation of global parameters such as overall performance and efficiency. The results indicate that the simulated leakage flow will decrease when dynamic gaps are used in comparison to static gaps, which is a consequence of the deformed structure that will generate smaller clearances. The leakage flow for the dynamic gaps will even be lower than for the static perfectly concentric case, mainly due to the reduction of clearances. The results also indicate that the dynamic eccentricity does not have a major influence on the leakage flow. The outcome from this study highlights the potentials of the described co-simulation approach for analysing the dynamics of the sealing gaps in a hydraulic percussion unit (i.e. gap heights, eccentricity ratios, etc.) including the evaluation of leakage flows and its impact on the overall performance. © 2021
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| 4. |
- Andersson, Håkan, 1970-, et al.
(författare)
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Simulation of wear in hydraulic percussion units using a co-simulation approach
- 2023
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Ingår i: International Journal of Modelling and Simulation. - : Taylor & Francis. - 0228-6203 .- 1925-7082. ; 43:3, s. 265-281
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a developed co-simulation method, which couples 1D-fluid and 3D-structural models, has been utilised to simulate wear in a hydraulic percussion unit. The effect of wear is generally detrimental on performance and lifetime for such units, but can also cause catastrophic failure and breakdown, requiring a total overhaul and replacement of core components. One experiment of standard straight impact was performed to investigate the tolerance against seizure. The percussion unit was operated at successively increasing operating pressures, and the level of wear was registered at each step, until seizure occurred. The co-simulation model was used to replicate the running conditions from the experiment to simulate the structural response to be used as input for the wear routine to calculate the wear depth. The wear pattern from the simulations corresponds well to the wear pattern from the experiment. Further, the effect of a misaligned impact on wear development was also studied, as this is a loading situation that typically occurs for hydraulic percussion units. The study demonstrates that the simulation method used has a potential for simulating wear and predicting seizure in hydraulic percussion units.
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| 5. |
- Andreassen, Björn, 1975-, et al.
(författare)
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Development of an efficient scanning and purging magnet system for IMRT with narrow high energy photon beams
- 2009
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 612:1, s. 201-208
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Tidskriftsartikel (refereegranskat)abstract
- Due to the clinical advantages of Intensity Modulated Radiation Therapy (IMRT) high flexibility and accuracy in intensity modulated dose delivery is desirable to really maximize treatment outcome. Although it is possible to deliver IMRT by using broad beams in combination with dynamic multileaf collimation the process is rather time consuming and inefficient. By using narrow scanned high energy photon beams the treatment outcome can be improved, the treatment time reduced and accurate 3D in vivo dose delivery monitoring is possible by PET-CT based dose delivery imaging of photo nuclear reactions in human tissues. Narrow photon beams can be produced by directing a low emittance high energy electron beam on a thin target, and then cleaning the therapeutic photon beam from transmitted high energy electrons, and photon generated charged leptons, with a dedicated purging magnet placed directly downstream of the target. To have an effective scanning and purging magnet system the purging magnet should be placed immediately after the bremsstrahlung target to deflect the transmitted electrons to an efficient electron stopper. In the static electron stopper the electrons should be safely collected independent of the desired direction of the therapeutic scanned photon beam. The SID (Source to Isocentre Distance) should preferably be short while retaining the ability to scan over a large area on the patient and consequently there are severe requirements both on the strength and the geometry of the scanning and purging magnets. In the present study an efficient magnet configuration with a purging and scanning magnet assembly is developed for electron energies in the 50-75 MeV range and a SID of 75 cm. For a bremsstrahlung target of 3mm Be these electron energies produce a photon beam of 25-17 mm FWHM (Full Width Half Maximum) at a SID of 75 cm. The magnet system was examined both in terms of the efficiency in scanning the narrow bremsstrahlung beam and the deflection of transmitted and photon generated electrons. The simulations show that its is possible to have a scan area on the patient of up to 43 x 40 cm2 for an incident electron energy of 50 MeV and 28 x 40 cm2 at 75 MeV, while at the same time adequately deflecting the transmitted electron beam.
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| 6. |
- Arthur, Rhonda, et al.
(författare)
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Serum glucose, triglycerides, and cholesterol in relation to prostate cancer death in the Swedish AMORIS study
- 2019
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Ingår i: Cancer Causes and Control. - : Springer. - 0957-5243 .- 1573-7225. ; 30:2, s. 195-206
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Lifestyle-related conditions such as obesity are associated with prostate cancer progression, but the associations with hyperglycemia and dyslipidemia are unclear. This study, therefore, aims to examine the association of glucose, triglycerides, and total cholesterol with prostate cancer death. Methods: From the Swedish AMORIS cohort, we selected 14,150 men diagnosed with prostate cancer between 1996 and 2011 who had prediagnostic measurements of serum glucose, triglycerides, and total cholesterol. Multivariable Cox proportional hazards regressionmodels were used to determine the hazard ratios for death in relation to the aforementioned metabolic markers. Results: Using clinical cut-off points, a non-significant positive association was observed between glucose and prostate cancer death. When compared to those with glucose in the lowest quartile, those in the highest quartile had greater risk of prostate cancer death (HR 1.19; 95% CI 1.02-1.39). However, neither total cholesterol nor triglycerides were associated with prostate cancer death. Glucose and triglycerides were positively associated with overall, cardiovascular, and other deaths. Hypercholesterolemia was only associated with risk of CVD death. Conclusion: Our results suggest that glucose levels may influence prostate cancer survival, but further studies using repeated measurements are needed to further elucidate how glucose levels may influence prostate cancer progression.
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| 7. |
- Bagheri, Mehdi
(författare)
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Model uncertainty of design tools to analyze block stability
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Block failure is one of the most common failure modes in tunnels. Design tools have some simplifications and, therefore, they also have some model uncertainties. The purpose of this licentiate thesis is to assess the model uncertainty for different design tools in order to estimate block stability. Different approaches of kinematic limit equilibrium (KLE) including conventional KLE, limited joint length, limited joint length and stress field consideration and probabilistic KLE were compared to that of DFN-DEM. In this approach, the results of the calibrated DFN-DEM with field mapping were considered to be of true value. The results show that the conventional KLE is overdesign due to it’s over simplification. By considering fracture length and stress field, the volume of predicted unstable blocks is reduced. The probabilistic approach of KLE by considering finite joint length and stress field predicts the volume of unstable blocks to be lower than DFN-DEM approach. Therefore there is a great model uncertainty of our standard design tools for block stability analysis. The assumption made in this study is that the results from DEM were considered to have a true value; the results from analytical solution based on joint relaxation process were compared to those of DEM in a different condition of depth, K0, apical and friction angle, Kn and Ks value, and ratio of Kn/Ks. The comparison shows that for shallow depth with K0 less than 1, analytical solution leads to an overestimation of block stability. The analytical solution predicts that the block is stable, while the analyses from numerical solution show the block is unstable. The analyses show that by increasing K0, accuracy of analytical solution also increases. Moreover, for the cases with close value of friction angle to semi-apical angle, the use of analytical solution is not recommended. As the ratio of Kn/Ks increases, the accuracy of analytical solution decreases. Increasing the angle ratio (ratio between semi-apical angle to friction angle) is one source of increasing uncertainty in the model. The analytical solution is very uncertain in cases with a low value of K0, and a high value of stiffness ratio and angle ratio. On the other hand, the analytical solution is more certain in conditions with a high value of K0 and a low value of stiffness ratio and angle ratio. According to current information (K0, angle ratio, stiffness ratio), one can determine the value of model uncertainty by using the diagrams presented in Chapter 6 of the thesis. The analyses show that by having more information about the key parameters, the model uncertainty could be identified more precisely. However, having more information means spending more money, and this increase in cost must be compared to the cost of failure or delay in the project or overdesign.
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| 8. |
- Bosco, Cecilia, et al.
(författare)
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Glucose, lipids and gamma-glutamyl transferase measured before prostate cancer diagnosis and secondly diagnosed primary tumours : a prospective study in the Swedish AMORIS cohort
- 2018
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Ingår i: BMC Cancer. - : BIOMED CENTRAL LTD. - 1471-2407. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Background: Improvements in detection and treatment of prostate cancer (PCa) translate into more men living with PCa, who are therefore potentially at risk of a secondly diagnosed primary tumour (SDPTs). Little is known about potential biochemical mechanisms linking PCa with the occurrence of SDPTs. The current study aims to investigate serum biomarkers of glucose and lipid metabolism and gamma-glutamyl transferase (GGT) measured prior to PCa diagnosis and their association with the occurrence of SDPTS.Methods: From the Swedish AMORIS cohort, we selected all men diagnosed with PCa between 1996 and 2011, with at least one of the five biomarkers of interest (glucose, fructosamine, triglycerides, total cholesterol (TC), GGT) measured on average 16 years before PCa diagnosis (n = 10,791). Multivariate Cox proportional hazards models were used to determine hazard ratios (HR) for risk of SDPTs (overall and subtypes) by levels of the five biomarkers. Effect modification of treatment was assessed.Results: 811 SDPTS were diagnosed during a median follow-up time of 5 years. Elevated levels of triglycerides (HR: 1.37, 95% CI: 1.17-1.60), TC (HR: 1.22, 95% CI: 1.04-1.42) and GGT (HR: 1.32, 95% CI: 1.02-1.71) were associated with an increased risk of SDPTs. Risk of SDPTs subtypes varied by biomarkers.Conclusion: Elevated levels of biomarkers of lipid metabolism and GGT measured prior to PCa diagnosis were associated with an increased risk of SDPTs, suggesting a potential common biochemical background for development of PCa and SDPTs.
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| 9. |
- Boström, Gustaf, et al.
(författare)
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Effects of a high-intensity functional exercise program on depressive symptoms among people with dementia in residential care : a randomized controlled trial
- 2016
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Ingår i: International Journal of Geriatric Psychiatry. - : Wiley. - 0885-6230 .- 1099-1166. ; 31:8, s. 868-878
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The aim of this study is to evaluate the effect of a high-intensity functional exercise program on depressive symptoms among older care facility residents with dementia.METHODS: Residents (n = 186) with a diagnosis of dementia, age ≥ 65 years, Mini-Mental State Examination score ≥ 10, and dependence in activities of daily living were included. Participants were randomized to a high-intensity functional exercise program or a non-exercise control activity conducted 45 min every other weekday for 4 months. The 15-item Geriatric Depression Scale (GDS) and the Montgomery-Åsberg Depression Rating Scale (MADRS) were administered by blinded assessors at baseline, 4, and 7 months.RESULTS: No difference between the exercise and control activity was found in GDS or MADRS score at 4 or 7 months. Among participants with GDS scores ≥ 5, reductions in GDS score were observed in the exercise and control groups at 4 months (-1.58, P = 0.001 and -1.54, P = 0.004) and 7 months (-1.25, P = 0.01 and -1.45, P = 0.007). Among participants with MADRS scores ≥ 7, a reduction in MADRS score was observed at 4 months in the control group (-2.80, P = 0.009) and at 7 months in the exercise and control groups (-3.17, P = 0.003 and -3.34, P = 0.002).CONCLUSIONS: A 4-month high-intensity functional exercise program has no superior effect on depressive symptoms relative to a control activity among older people with dementia living in residential care facilities. Exercise and non-exercise group activities may reduce high levels of depressive symptoms.
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| 10. |
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| 11. |
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| 12. |
- Cheng, Arthur J., et al.
(författare)
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Doublet discharge stimulation increases sarcoplasmic reticulum Ca2+ release and improves performance during fatiguing contractions in mouse muscle fibres
- 2013
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Ingår i: Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 591:15, s. 3739-3748
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Tidskriftsartikel (refereegranskat)abstract
- Double discharges (doublets) of motor neurones at the onset of contractions increase both force and rate of force development during voluntary submaximal contractions. The purpose of this study was to examine the role of doublet discharges on force and myoplasmic free [Ca2+] ([Ca2+](i)) during repeated fatiguing contractions, using a stimulation protocol mimicking the in vivo activation pattern during running. Individual intact fibres from the flexor digitorum brevis muscle of mice were stimulated at 33 degrees C to undergo 150 constant-frequency (five pulses at 70 Hz) or doublet (an initial, extra pulse at 200 Hz) contractions at 300 ms intervals. In the unfatigued state, doublet stimulation resulted in a transient (approximate to 10 ms) approximate doubling of [Ca2+](i), which was accompanied by a greater force-time integral (approximate to 70%) and peak force (approximate to 40%) compared to constant frequency contractions. Moreover, doublets markedly increased force-time integral and peak force during the first 25 contractions of the fatiguing stimulation. In later stages of fatigue, addition of doublets increased force production but the increase in force production corresponded to only a minor portion of the fatigue-induced reduction in force. In conclusion, double discharges at the onset of contractions effectively increase force production, especially in early stages of fatigue. This beneficial effect occurs without additional force loss in later stages of fatigue, indicating that the additional energy cost induced by doublet discharges to skeletal muscle is limited.
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| 13. |
- Cheng, Arthur J., et al.
(författare)
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Post-exercise recovery of contractile function and endurance in humans and mice is accelerated by heating and slowed by cooling skeletal muscle
- 2017
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Ingår i: Journal of Physiology. - : John Wiley & Sons. - 0022-3751 .- 1469-7793. ; 595:24, s. 7413-7426
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Tidskriftsartikel (refereegranskat)abstract
- Key points: We investigated whether intramuscular temperature affects the acute recovery of exercise performance following fatigue-induced by endurance exercise. Mean power output was better preserved during an all-out arm-cycling exercise following a 2 h recovery period in which the upper arms were warmed to an intramuscular temperature of ˜ 38°C than when they were cooled to as low as 15°C, which suggested that recovery of exercise performance in humans is dependent on muscle temperature. Mechanisms underlying the temperature-dependent effect on recovery were studied in intact single mouse muscle fibres where we found that recovery of submaximal force and restoration of fatigue resistance was worsened by cooling (16-26°C) and improved by heating (36°C). Isolated whole mouse muscle experiments confirmed that cooling impaired muscle glycogen resynthesis. We conclude that skeletal muscle recovery from fatigue-induced by endurance exercise is impaired by cooling and improved by heating, due to changes in glycogen resynthesis rate.Manipulation of muscle temperature is believed to improve post-exercise recovery, with cooling being especially popular among athletes. However, it is unclear whether such temperature manipulations actually have positive effects. Accordingly, we studied the effect of muscle temperature on the acute recovery of force and fatigue resistance after endurance exercise. One hour of moderate-intensity arm cycling exercise in humans was followed by 2 h recovery in which the upper arms were either heated to 38°C, not treated (33°C), or cooled to ∼15°C. Fatigue resistance after the recovery period was assessed by performing 3 × 5 min sessions of all-out arm cycling at physiological temperature for all conditions (i.e. not heated or cooled). Power output during the all-out exercise was better maintained when muscles were heated during recovery, whereas cooling had the opposite effect. Mechanisms underlying the temperature-dependent effect on recovery were tested in mouse intact single muscle fibres, which were exposed to ∼12 min of glycogen-depleting fatiguing stimulation (350 ms tetani given at 10 s interval until force decreased to 30% of the starting force). Fibres were subsequently exposed to the same fatiguing stimulation protocol after 1-2 h of recovery at 16-36°C. Recovery of submaximal force (30 Hz), the tetanic myoplasmic free [Ca2+] (measured with the fluorescent indicator indo-1), and fatigue resistance were all impaired by cooling (16-26°C) and improved by heating (36°C). In addition, glycogen resynthesis was faster at 36°C than 26°C in whole flexor digitorum brevis muscles. We conclude that recovery from exhaustive endurance exercise is accelerated by raising and slowed by lowering muscle temperature.
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Duffy, Stephen W., et al.
(författare)
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Beneficial effect of consecutive screening mammography examinations on mortality from breast cancer : a prospective study
- 2021
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Ingår i: Radiology. - : Radiological Society of North America (RSNA). - 0033-8419 .- 1527-1315. ; 299:3, s. 541-547
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Tidskriftsartikel (refereegranskat)abstract
- Background: Previously, the risk of death from breast cancer was analyzed for women participating versus those not participating in the last screening examination before breast cancer diagnosis. Consecutive attendance patterns may further refine estimates.Purpose: To estimate the effect of participation in successive mammographic screening examinations on breast cancer mortality.Materials and Methods: Participation data for Swedish women eligible for screening mammography in nine counties from 1992 to 2016 were linked with data from registries and regional cancer centers for breast cancer diagnosis, cause, and date of death (Uppsala University ethics committee registration number: 2017/147). Incidence-based breast cancer mortality was calculated by whether the women had participated in the most recent screening examination prior to diagnosis only (intermittent participants), the penultimate screening examination only (lapsed participants), both examinations (serial participants), or neither examination (serial nonparticipants). Rates were analyzed with Poisson regression. We also analyzed incidence of breast cancers proving fatal within 10 years.Results: Data were available for a total average population of 549 091 women (average age, 58.9 years 6 6.7 [standard deviation]). The numbers of participants in the four groups were as follows: serial participants, 392 135; intermittent participants, 41 746; lapsed participants, 30 945; and serial nonparticipants, 84 265. Serial participants had a 49% lower risk of breast cancer mortality (relative risk [RR], 0.51; 95% CI: 0.48, 0.55; P ,.001) and a 50% lower risk of death from breast cancer within 10 years of diagnosis (RR, 0.50; 95% CI: 0.46, 0.55; P ,.001) than serial nonparticipants. Lapsed and intermittent participants had a smaller reduction. Serial participants had significantly lower risk of both outcomes than lapsed or intermittent participants. Analyses correcting for potential biases made little difference to the results.Conclusion: Women participating in the last two breast cancer screening examinations prior to breast cancer diagnosis had the largest reduction in breast cancer death. Missing either one of the last two examinations conferred a significantly higher risk.
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| 18. |
- Duffy, Stephen W., et al.
(författare)
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Mammography screening reduces rates of advanced and fatal breast cancers : Results in 549,091 women
- 2020
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Ingår i: Cancer. - : John Wiley & Sons. - 0008-543X .- 1097-0142. ; 126:13, s. 2971-2979
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Tidskriftsartikel (refereegranskat)abstract
- Background: It is of paramount importance to evaluate the impact of participation in organized mammography service screening independently from changes in breast cancer treatment. This can be done by measuring the incidence of fatal breast cancer, which is based on the date of diagnosis and not on the date of death.Methods: Among 549,091 women, covering approximately 30% of the Swedish screening‐eligible population, the authors calculated the incidence rates of 2473 breast cancers that were fatal within 10 years after diagnosis and the incidence rates of 9737 advanced breast cancers. Data regarding each breast cancer diagnosis and the cause and date of death of each breast cancer case were gathered from national Swedish registries. Tumor characteristics were collected from regional cancer centers. Aggregated data concerning invitation and participation were provided by Sectra Medical Systems AB. Incidence rates were analyzed using Poisson regression.Results: Women who participated in mammography screening had a statistically significant 41% reduction in their risk of dying of breast cancer within 10 years (relative risk, 0.59; 95% CI, 0.51‐0.68 [P < .001]) and a 25% reduction in the rate of advanced breast cancers (relative risk, 0.75; 95% CI, 0.66‐0.84 [P < .001]).Conclusions: Substantial reductions in the incidence rate of breast cancers that were fatal within 10 years after diagnosis and in the advanced breast cancer rate were found in this contemporaneous comparison of women participating versus those not participating in screening. These benefits appeared to be independent of recent changes in treatment regimens.
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| 19. |
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| 20. |
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| 21. |
- Essen, Anneli, et al.
(författare)
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Baseline serum folate, vitamin B12 and the risk of prostate and breast cancer using data from the Swedish AMORIS cohort
- 2019
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Ingår i: Cancer Causes and Control. - : SPRINGER. - 0957-5243 .- 1573-7225. ; 30:6, s. 603-615
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The roles of folate and vitamin B12 in prostate cancer (PCa) or breast cancer (BC) development are unclear. We investigated their roles using the prospective Swedish Apolipoprotein MOrtality RISk (AMORIS) study.Methods: 8,783 men and 19,775 women with vitamin B12 and folate serum measurements were included. Their associations with PCa and BC risk categories were evaluated using Cox proportional hazards regression.Results: During mean follow-up of 13years, 703 men developed PCa. There was an inverse association between folate>32nmol/L and high-risk PCa [hazard ratio (HR) 0.12, 95% confidence interval (CI) 0.02-0.90], and a positive association between folate<5nmol/L and metastatic PCa (HR 5.25, 95% CI 1.29-21.41), compared with folate 5-32nmol/L. No associations with vitamin B12 were found. 795 women developed BC during mean follow-up of 14years. When restricting to the fasting population, there was a positive association between folate>32nmol/L and BC (HR 1.47, 95% CI 1.06-2.04).Conclusion: High folate levels may protect against PCa and low folate levels may increase risk of metastatic PCa. High fasting folate levels may be associated with an increased BC risk. Vitamin B12 was not found to be linked with risk of PCa or BC. Longitudinal studies with serum and dietary information could help define new prevention targets and add information on the role of folate fortification.
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| 22. |
- Ghoshal, Arunangshu, et al.
(författare)
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Thyroid cancer risk in the Swedish AMORIS study : the role of inflammatory biomarkers in serum.
- 2018
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 9:1, s. 774-782
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Tidskriftsartikel (refereegranskat)abstract
- Chronic inflammation is one of the underlying risks associated with thyroid cancer. We ascertained the association between commonly measured serum biomarkers of inflammation and the risk of thyroid cancer in Swedish Apolipoprotein-related MORtality RISk (AMORIS) study. 226,212 subjects had baseline measurements of C-reactive protein, albumin and haptoglobin. Leukocytes were measured in a subgroup of 63,845 subjects. Associations between quartiles and dichotomized values of inflammatory markers and risk of thyroid cancer were analysed using multivariate Cox proportional hazard models. 202 individuals were diagnosed with thyroid cancer during a mean follow-up of 19.6 years. There was a positive association between lower albumin levels and risk of developing thyroid cancer [Hazard Ratio for albumin ≤ 40 g/L: 1.50 (95% Confidence Interval = 1.04-2.16)]. When stratified by a metabolic score, we observed similar association for albumin with higher HR among those with metabolic score ≥ 1, as compared to those with metabolic score of 0 [HR 1.98 (95% CI = 1.11-3.54) vs 1.17 (95% CI = 0.72-1.89)] (P = 0.19). Apart from albumin, none of the serum markers of inflammation studied showed a link with the risk of developing thyroid cancer-suggesting that the role of inflammation may be more complicated and requires assessment of more specialised measurements of inflammation.
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| 23. |
- Ghuan, Sundeep, et al.
(författare)
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Serum inflammatory markers and colorectal cancer risk and survival
- 2017
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Ingår i: British Journal of Cancer. - : NATURE PUBLISHING GROUP. - 0007-0920 .- 1532-1827. ; 116:10, s. 1358-1365
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Tidskriftsartikel (refereegranskat)abstract
- Background: Inflammation has been linked with development of some cancers. We investigated systemic inflammation in relation to colorectal cancer incidence and subsequent survival using common serum inflammatory markersDesign: A cohort of men and women aged 20 years and older in greater Stockholm area with serum C-reactive protein (CRP) and albumin measured between 1986 and 1999 were included (n-325 599). A subset of these had baseline measurements of haptoglobin and leukocytes. Multivariable Cox regression was performed to assess risk of colorectal cancer by levels of inflammatory markers, adjusting for potential confounders. Analyses were stratified by circulating glucose, total cholesterol and triglycerides. Overall and CRC-specific death following diagnosis were assessed as secondary outcomes.Results: A total of 4764 individuals were diagnosed with colorectal cancer. A positive association between haptoglobin and colorectal cancer incidence was found (hazard ratio (HR): 1.17; 95% CI: 1.06-1.28). A positive association was also observed with leukocytes (HR: 1.21; 95% CI: 1.03-1.42). No evidence of association was noted between CRP and colorectal cancer risk. Higher risks of all-cause death were seen with haptoglobin and leukocytes levels. Higher haptoglobin levels were linked with an increased risk of colorectal cancer death (HR: 1.19; 95% CI: 1.01-1.41).Conclusions: Prediagnostic systemic inflammation may impact colorectal cancer incidence and survival; therefore, prompting investigations linking inflammatory pathways preceding colorectal cancer with disease severity and progression.
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| 24. |
- Hakansson, Sara, et al.
(författare)
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Moderate frequency of BRCA1 and BRCA2 germ-line mutations in Scandinavian familial breast cancer
- 1997
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Ingår i: American Journal of Human Genetics. - 0002-9297. ; 60:5, s. 1068-1078
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies of high-risk breast cancer families have proposed that two major breast cancer-susceptibility genes, BRCA1 and BRCA2, may account for at least two-thirds of all hereditary breast cancer. We have screened index cases from 106 Scandinavian (mainly southern Swedish) breast cancer and breast-ovarian cancer families for germ-line mutations in all coding exons of the BRCA1 and BRCA2 genes, using the protein-truncation test, SSCP analysis, or direct sequencing. A total of 24 families exhibited 11 different BRCA1 mutations, whereas 11 different BRCA2 mutations were detected in 12 families, of which 3 contained cases of male breast cancer. One BRCA2 mutation, 4486delG, was found in two families of the present study and, in a separate study, also in breast tumors from three unrelated males with unknown family history, suggesting that at least one BRCA2 founder mutation exists in the Scandinavian population. We report 1 novel BRCA1 mutation, eight additional cases of 4 BRCA1 mutations described elsewhere, and 11 novel BRCA2 mutations (9 frameshift deletions and 2 nonsense mutations), of which all are predicted to cause premature truncation of the translated products. The relatively low frequency of BRCA1 and BRCA2 mutations in the present study could be explained by insufficient screening sensitivity to the location of mutations in uncharacterized regulatory regions, the analysis of phenocopies, or, most likely, within predisposed families, additional uncharacterized BRCA genes.
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| 27. |
- Holmberg, Björn, 1974-
(författare)
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Estimating Human Limb Motion Using Skin Texture and Particle Filtering
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Estimating human motion is the topic of this thesis. We are interested in accurately estimating the motion of a human body using only video images capturing the subject in motion. Video images from up to two cameras are considered.The first main topic of the thesis is to investigate a new type of input data. This data consists of some sort of texture. This texture can be added to the human body segment under study or it can be the actual texture of the skin.In paper I we investigate if added texture together with the use of a two camera system can provide enough information to make it possible to estimate the knee joint center location. Evaluation is made using a marker based system that is run in parallel to the two camera video system. The results from this investigation show promise for the use of texture. The marker and texture based estimates differ in absolute values but the variations are similar indicating that texture is in fact usable for this purpose.In paper II and III we investigate further the usability in images of skin texture as input for motion estimation. Paper II approaches the problem of estimating human limb motion in the image plane. An image histogram based mutual information criterion is used to decide if an extracted image patch from frame k is a good match to some location in frame k+1. Eval- uation is again performed using a marker based system synchronized to the video stream. The results are very promising for the application of skin texture based motion estimation in 2D. In paper III, basically the same approach is taken as in paper II with the substantial difference that here estimation of three dimensional motion is addressed. Two video cameras are used and the image patch matching is performed both between cameras (inter-camera) in frame k and also in each cameras images (intra-camera) for frame k to k+1. The inter-camera matches yield triangulated three dimensional estimates on the approximate surface of the skin. The intra-camera matches provide a way to connect the three dimensional points between frame k and k+1 The resulting one step three dimensional trajectories are then used to estimate rigid body motion using least squares methods. The results show that there is still some work to be done before this texture based method can be an alternative to the marker based methods.In paper IV the second main topic of the thesis is discussed. Here we present an investigation in using model based techniques for the purpose of estimating human motion. A kinematic model of the thigh and shank segments are built with an anatomic model of the knee. Using this model, the popular particle filter and typical simulated data from the triangulation in paper III, an estimate of the motion variables in the thigh and shank segment can be achieved. This also includes one static model parameter used to describe the knee model. The results from this investigation show good promise for the use of triangulated skin texture as input to such a model based approach.
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| 28. |
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| 29. |
- Holmberg, Björn, et al.
(författare)
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On the Plausibility of Using Skin Texture as Virtual Markers in the Human Motion Analysis Context, a 2D Study
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- For the first time it is shown that skin texture can be used as a means to match human limb surfaces between different image frames. The results are limited to motion in two dimensions. It is shown that images with a resolution that can be produced in today existing video camera hardware are usable. This is very encouraging for the future of clinical marker free human motion analysis applications. The next step will be to investigate if these results can be extended to three dimensions using a stereo camera setup. The method uses histogram information as a means to match small image patches to one another. The histogram matching is performed using a Mutual Information criterion as the cost function and Simulated Annealing as the optimization algorithm.
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| 30. |
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| 31. |
- Holmberg, Björn, et al.
(författare)
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Possibilities of texture based motion analysis
- 2006
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Ingår i: Computer Methods and Programs in Biomedicine. - : Elsevier BV. - 0169-2607 .- 1872-7565. ; 84:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of motion patterns in the human locomotion apparatus is important in many clinical areas like orthopaedics, physiotherapy, neurology, and sports medicine. Today marker based human motion analysis (HMA) is completely dominant in the clinical context. Technically, these systems are stable and dependable, and about a dozen variants are commercially available. One drawback of such systems is the time consuming and error prone marker placement. The purpose of the present contribution is to show that it is possible, with existing simple technology and methods, to build systems that do not depend on anatomically placed markers and yet produce an accuracy in knee joint center estimation comparable to marker based systems. It is shown that texture based methods can give estimates of knee joint center of rotation that can be compared to knee joint center estimates from marker based systems. Due to different definitions of the knee joint center position some bias is seen between the two estimates.
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| 32. |
- Holmberg, Björn
(författare)
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Towards markerless analysis of human motion
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The topic for this thesis is the analysis of human movement, or more specifically, markerless analysis of human movement from video material. By markerless analysis is meant that the full image material is used as input in contrast with traditional marker systems that only use the positions of marker centers. The basic idea is to use more of the information in the images to improve the analysis.Starting of with the aim of markerless analysis an application is designed that use, to the subject added texture to estimate the position of the knee joint center in real images. The approach show the plausibility of using subject texture for estimation purposes.Another issue that is addressed is how one can generate synthetic image data. Using basic tools of graphics programming a virtual environment used to synthesize data is created. This environment is also used to evaluate some different camera solutions.One method to make three dimensional reconstruction from multiple images of an object is tested using the synthetic data. The method is based on a "brute force" approach and does not show good performance in terms of computing speed. With appropriate representations of the three dimensional objects, mathematical methods might speed up the analysis.
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| 33. |
- Holmberg, Gustav, 1967, et al.
(författare)
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Mångdisciplinära forskargrupper – förutsättningar, ledning och genusmönster
- 2012
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Ingår i: Widén, K. & Lövkrona. I. (Red) AKKA AKkademiska Kollegors ansvar. Ledarutvecklingsprogram för kvinnor och män vid Lunds universitet 2010-2011 Erfarenheter från ett ledarskapsprogram. - Lund : Lunds universitet. - 9789163703522 ; , s. 147-161
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 34. |
- Holmberg, Håkan, et al.
(författare)
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Economic evaluation of screening for prostate cancer : a randomized populaionbased programme during a 10 year period in Sweden
- 1998
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Ingår i: Health Policy. - 0168-8510 .- 1872-6054. ; 45:2, s. 133-147
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Tidskriftsartikel (refereegranskat)abstract
- Prostate cancer is a growing health problem representing considerable costs. Screening and early curative treatment may reduce morbidity and possibly prevent future escalating costs. However, population screening programmes are generally not well accepted at present due to uncerainty about whether screening for prostate cancer can result in reduced mortality. Evidence from large, randomized, controlled trials is still lacking. The objective of this study was to calculate clinical and economic consequences of general prostate cancer screening based on a limited screening trial in a Swedish community and a decision-tree model. A random selection of 1492 men (50–69 years) were invited to repeated screening in 1987. They have been examined every third year (four rounds). The other 7679 men in the population act as controls. The results show that the total incremental health care costs for prostate cacer will increase by 179 million SEK per year with screening compared to no-screening. The number of detected cases of localized cancer will increase by about 1000, which represents an additional cost of about 158 000 SEK per case. In conclusion, general screening for prostate cancer can be performed with a reasonable cost per detected localized cancer. Information on the long-term effect on life quality and cancer mortality is unknown.
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| 35. |
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| 36. |
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| 37. |
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| 38. |
- Holmberg, Lina, et al.
(författare)
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Penetrating Trauma on the Rise – Nine-year Trends of Severe Trauma in Sweden
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- PurposeSweden has an established trauma system involving national trauma criteria and a registry, SweTrau, since over a decade. Meanwhile, the injury panorama has evolved, with an increase in gang-related violence in the Swedish community. In this study, we aimed to investigate long-term trends in mortality, management and trauma type in two major Swedish trauma centers over a nine-year period. MethodsAll trauma patients with a New Injury Score (NISS)>15 or a Trauma Alert call during 2013-2021 were identified in the participating centers’ SweTrau registries. Data were analysed regarding mortality, proportion of emergency interventions, intensive care unit (ICU) admissions, mechanism of injury and type of trauma (penetrating or blunt). To assess trends, Chi-Squared test for trend and JoinPoint regression method were used. ResultsA total of 10585 patients were included in the study. Mortality remained unchanged over time in patients with NISS>15 (10.0% - 10.9%, p=0.963) but increased in NISS<15 (1.3% - 2.7%, p=0.005), partly comprising penetrating trauma, suicides and traumatic cardiac arrests. For NISS>15, the proportion undergoing emergency interventions was stable (53.9%-48.8%, p=0.297) while ICU admissions declined (62.1%-45.7%, p<0.001). Penetrating trauma increased (12.4%-19.6%, p<0.001), including knife (10.0%-15.7%, p<0.001) and gunshot wounds (2.3%-3.8%, p<0.001), whereas accidents involving motorcycles (8.8%-7.0%, p=0.004) and pedestrians (5.3%-2.2%, p<0.001) decreased. ConclusionsIn this trend analysis at two major Swedish trauma centers during 2013-2021, penetrating trauma increased with over 50% while traffic injuries decreased. The rise in mortality in patients with NISS<15 is concerning and requires further evaluation, as do the reduction in ICU admissions.
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| 39. |
- Holmberg, Lina
(författare)
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Trauma Care - Implementation, Evaluation and Validation
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Trauma is a major cause of death and morbidity in all ages, which makes continuous improvement of trauma care a high priority. During the last decades, Sweden’s trauma system has evolved with initiation of a national trauma registry (SweTrau) in 2011 and the Swedish National Trauma Triage criteria (SNTTC) in 2017. However, the Swedish trauma panorama has evolved as well, something this thesis aimed to explore, alongside with evaluating the safety and accuracy of the SNTTC and performing the first validation of SweTrau. Paper I is a prospective stepped-wedge cohort study, showing unchanged 30-day mortality, over- and undertriage after the implementation of the SNTTC, as well as a reduction of the lowest level of trauma call by almost 50%, proving that the SNTTC are safe to use. In Paper II, a retrospective multicentre cohort study, the SNTTC are further investigated, displaying a sensitivity of almost 85% while also assessing specificity, positive predictive value (PPV) and positive likelihood ratio (LR+). With no additional enhancing criteria found, the SNTTC are concluded to efficiently identify severely injured patients. Paper III reports the first validation of SweTrau; an on-site re-registration compared with the original registration in SweTrau. It demonstrates that the data in SweTrau is reliable, with high accuracy (85.8%), correctness (89.7%), data completeness (88.5%) and correlation (87.5%), while being comparable to international trauma registries using the Utstein template of trauma. Case completeness and timeliness are identified as areas of improvement. In Paper IV, nine-year trauma trends in two major trauma centres are analysed in a retrospective cohort study. A sharp reduction in intensive care unit admissions is seen, as well as a worrying increase in penetrating trauma (>50%) and mortality for patients with a low injury severity score (1.3%-2.7%, p=0.005), all of which require further investigation. In conclusion; this thesis has confirmed that the SNTTC are safe and efficient, as well as pin-pointed important trauma areas to focus on in the future. Finally, it has established the validity of the data in SweTrau - a major source of Swedish trauma research.
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| 40. |
- Holmberg, Lina, et al.
(författare)
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Trauma triage criteria as predictors of severe injury-a Swedish multicenter cohort study
- 2022
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Ingår i: BMC Emergency Medicine. - : Springer Nature. - 1471-227X. ; 22:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Adequate performance of trauma team activation (TTA) criteria is important in order to accurately triage trauma patients. The Swedish National Trauma Triage Criteria (SNTTC) consists of 29 criteria that trigger either a Trauma Alert, the highest level of TTA, or a Trauma Response. This study aimed to evaluate the SNTTC and its accuracy in predicting a severely injured patient in a multicenter setting. Methods A cohort study in Sweden involving six trauma receiving hospitals. Data was collected from the Swedish Trauma Registry. Some 626 patients were analyzed with regard to the specific criteria used to initiate the TTA, injury severity with New Injury Severity Score (NISS) and emergency interventions. Sensitivity, specificity, positive predictive value (PPV) and positive likelihood ratio (LR+) of the criteria were calculated, as well as undertriage and overtriage. Results All 29 criteria of SNTTC had a sensitivity > 80% for identifying a severely injured patient. The 16 Trauma Alert Criteria had a lower sensitivity of 62.6% but higher LR+ (3.5 vs all criteria 1.4), specificity (82.3 vs 39.1%) and PPV (55.4 vs 37.6%) and the highest accuracy (AUC 0.724). When using only the six physiological criteria, sensitivity (44.8%) and accuracy (AUC 0.690) decreased while LR+ (6.7), specificity (93.3%) and PPV (70.2%) improved. Conclusion SNTTC is efficient in identifying severely injured patients. The current set of criteria exhibits the best sensitivity compared to other examined combinations and no additional criterion was found to improve the protocol enough to promote a change.
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| 41. |
- Holmberg, Lina, et al.
(författare)
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Validation of the Swedish Trauma Registry (SweTrau)
- 2023
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Ingår i: European Journal of Trauma and Emergency Surgery. - : Springer. - 1863-9933 .- 1863-9941. ; 49:4, s. 1627-1637
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Tidskriftsartikel (refereegranskat)abstract
- PurposeValidation of registries is important to ensure accuracy of data and registry-based research. This is often done by comparisons of the original registry data with other sources, e.g. another registry or a re-registration of data. Founded in 2011, the Swedish Trauma Registry (SweTrau) consists of variables based on international consensus (the Utstein Template of Trauma). This project aimed to perform the first validation of SweTrau.MethodsOn-site re-registration was performed on randomly selected trauma patients and compared to the registration in SweTrau. Accuracy (exact agreement), correctness (exact agreement plus data within acceptable range), comparability (similarity with other registries), data completeness (1-missing data) and case completeness (1-missing cases) were deemed as either good (≥85%), adequate (70–84%) or poor (< 70%). Correlation was determined as either excellent (≥0.8), strong (0.6–0.79), moderate (0.4–0.59) or weak (< 0.4).ResultsThe data in SweTrau had good accuracy (85.8%), correctness (89.7%) and data completeness (88.5%), as well as strong or excellent correlation (87.5%). Case completeness was 44.3%, however, for NISS > 15 case completeness was 100%. Median time to registration was 4.5 months, with 84.2% registered one year after the trauma. The comparability showed an accordance with the Utstein Template of Trauma of almost 90%.ConclusionsThe validity of SweTrau is good, with high accuracy, correctness, data completeness and correlation. The data are comparable to other trauma registries using the Utstein Template of Trauma; however, timeliness and case completeness are areas of improvement.
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| 42. |
- Holmberg, M., et al.
(författare)
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Evaluation of pre-grouting for the city line project using the RTGC method
- 2012
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Ingår i: ISRM International Symposium - EUROCK 2012. - : International Society for Rock Mechanics.
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Konferensbidrag (refereegranskat)abstract
- An access tunnel for the City Line project in Stockholm was excavated in the early parts of 2010. The works also included pre-grouting with cement. The performance of pre-grouting operation was evaluated for 14 continuous fans that included 326 grouted holes. A method called “Real Time Grouting Control (RTGC)”was used in the analysis. It is shown how the RTGC method can be used to investigate the effectiveness of existing stop criteria. It is first time an evaluation using RTGC carried out in this magnitude. The water inflow to the tunnel after grouting satisfied requirements. The grouting effect is quantified by assessments of the average conductivity of the rock mass and of the grout spread outside the tunnel. The evaluation indicates that the stop criteria in the design were chosen conservatively relative to the achieved grouting results. A model is discussed where the required grout spread is used as a design parameter to quantify the potential for reducing the pumping time.
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| 43. |
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| 44. |
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| 45. |
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| 46. |
- Holmberg, Per, 1964, et al.
(författare)
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Att rista tid och rum i sten
- 2011
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Ingår i: Funktionell textanalys. - Stockholm : Norstedts. - 9789113032764 ; , s. 204-221
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 47. |
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| 48. |
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| 49. |
- Jönsson, Håkan, et al.
(författare)
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Tidens tecken
- 2002
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Ingår i: Identitet: om varumärken, tecken och symboler. ; , s. 61-66
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 50. |
- Kainu, T, et al.
(författare)
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Somatic deletions in hereditary breast cancers implicate 13q21 as a putative novel breast cancer susceptibility locus
- 2000
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Ingår i: Proceedings of the National Academy of Sciences. - 1091-6490. ; 97:17, s. 9603-9608
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Tidskriftsartikel (refereegranskat)abstract
- A significant proportion of familial breast cancers cannot be explained by mutations in the BRCA1 or BRCA2 genes. We applied a strategy to identify predisposition loci for breast cancer by using mathematical models to identify early somatic genetic deletions in tumor tissues followed by targeted linkage analysis. Comparative genomic hybridization was used to study 61 breast tumors from 37 breast cancer families with no identified BRCA1 or BRCA2 mutations. Branching and phylogenetic tree models predicted that loss of 13q was one of the earliest genetic events in hereditary cancers. In a Swedish family with five breast cancer cases, all analyzed tumors showed distinct 13q deletions, with the minimal region of loss at 13q21-q22. Genotyping revealed segregation of a shared 13q21 germ-line haplotype in the family. Targeted linkage analysis was carried out in a set of 77 Finnish, Icelandic, and Swedish breast cancer families with no detected BRCA1 and BRCA2 mutations. A maximum parametric two-point logarithm of odds score of 2.76 was obtained for a marker at 13q21 (D13S1308, theta = 0.10). The multipoint logarithm of odds score under heterogeneity was 3.46. The results were further evaluated by simulation to assess the probability of obtaining significant evidence in favor of linkage by chance as well as to take into account the possible influence of the BRCA2 locus, located at a recombination fraction of 0.25 from the new locus. The simulation substantiated the evidence of linkage at D13S1308 (P < 0.0017). The results warrant studies of this putative breast cancer predisposition locus in other populations.
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