| 1. |
- Cunha, Sara I., et al.
(författare)
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Endothelial ALK1 Is a Therapeutic Target to Block Metastatic Dissemination of Breast Cancer.
- 2015
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Ingår i: Cancer Research. - 1538-7445 .- 0008-5472. ; 75:12, s. 2445-2456
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Tidskriftsartikel (refereegranskat)abstract
- Exploration of new strategies for the prevention of breast cancer metastasis is justifiably at the center of clinical attention. In this study, we combined a computational biology approach with mechanism-based preclinical trials to identify inhibitors of activin-like receptor kinase (ALK) 1 as effective agents for blocking angiogenesis and metastasis in breast cancer. Pharmacologic targeting of ALK1 provided long-term therapeutic benefit in mouse models of mammary carcinoma, accompanied by strikingly reduced metastatic colonization as a monotherapy or part of combinations with chemotherapy. Gene-expression analysis of breast cancer specimens from a population-based nested case-control study encompassing 768 subjects defined endothelial expression of ALK1 as an independent and highly specific prognostic factor for metastatic manifestation, a finding that was corroborated in an independent clinical cohort. Overall, our results suggest that pharmacologic inhibition of endothelial ALK1 constitutes a tractable strategy for interfering with metastatic dissemination of breast cancer. Cancer Res; 75(12); 2445-56. ©2015 AACR.
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| 2. |
- Prakash, Varsha, et al.
(författare)
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Ribosome biogenesis during cell cycle arrest fuels EMT in development and disease
- 2019
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Ribosome biogenesis is a canonical hallmark of cell growth and proliferation. Here we show that execution of Epithelial-to-Mesenchymal Transition (EMT), a migratory cellular program associated with development and tumor metastasis, is fueled by upregulation of ribosome biogenesis during G1/S arrest. This unexpected EMT feature is independent of species and initiating signal, and is accompanied by release of the repressive nucleolar chromatin remodeling complex (NoRC) from rDNA, together with recruitment of the EMT-driving transcription factor Snai1 (Snail1), RNA Polymerase I (Pol I) and the Upstream Binding Factor (UBF). EMT-associated ribosome biogenesis is also coincident with increased nucleolar recruitment of Rictor, an essential component of the EMT-promoting mammalian target of rapamycin complex 2 (mTORC2). Inhibition of rRNA synthesis in vivo differentiates primary tumors to a benign, Estrogen Receptor-alpha (ER alpha) positive, Rictor-negative phenotype and reduces metastasis. These findings implicate the EMT-associated ribosome biogenesis program with cellular plasticity, de-differentiation, cancer progression and metastatic disease.
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| 3. |
- Roswall, Pernilla, et al.
(författare)
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Microenvironmental control of breast cancer subtype elicited through paracrine platelet-derived growth factor-CC signaling
- 2018
-
Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1546-170X .- 1078-8956. ; 24, s. 463-473
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Tidskriftsartikel (refereegranskat)abstract
- Breast tumors of the basal-like, hormone receptor-negative subtype remain an unmet clinical challenge, as there is high rate of recurrence and poor survival in patients following treatment. Coevolution of the malignant mammary epithelium and its underlying stroma instigates cancer-associated fibroblasts (CAFs) to support most, if not all, hallmarks of cancer progression. Here we delineate a previously unappreciated role for CAFs as determinants of the molecular subtype of breast cancer. We identified paracrine crosstalk between cancer cells expressing platelet-derived growth factor (PDGF)-CC and CAFs expressing the cognate receptors in human basal-like mammary carcinomas. Genetic or pharmacological intervention of PDGF-CC activity in mouse models of cancer resulted in conversion of basal-like breast cancers into a hormone receptor-positive state that enhanced sensitivity to endocrine therapy in previously resistant tumors. We conclude that specification of breast cancer to the basal-like subtype is under microenvironmental control and is therapeutically actionable.
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| 4. |
- Andersson, Sara, et al.
(författare)
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Damage monitoring of ship FRP during exposure to explosion impacts
- 2011
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Konferensbidrag (refereegranskat)abstract
- Fiber Reinforced Plastics (FRP) has been used by Kockums' shipyard in the manufacturing of ships over 35 years, during which time is has been proven to be durable and practical. The light weight makes it a more and more attractive material as energy and material expenditure decreases are required. A special application is the Composite Superstructure Concept [1] where composite materials are added on top of a steel hull, which decreases the weight and running costs considerably, and makes it possible to even add extra levels while keeping the same center of gravity. If efficient condition monitoring systems can keep track of emerging damages of the structure, the weight may be even more reduced and the interval between maintenance inspections may be prolonged. As important steps in this process, a ship mock-up section was subjected to increased levels of explosive underwater impacts, and the damage progression in the hull was monitored by a nonlinear acoustic technique.
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| 5. |
- Elding Larsson, Helena, et al.
(författare)
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Pandemrix® vaccination is not associated with increased risk of islet autoimmunity or type 1 diabetes in the TEDDY study children
- 2018
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 61:1, s. 193-202
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis: During the A/H1N1 2009 (A/California/04/2009) pandemic, mass vaccination with a squalene-containing vaccine, Pandemrix®, was performed in Sweden and Finland. The vaccination was found to cause narcolepsy in children and young adults with the HLA-DQ 6.2 haplotype. The aim of this study was to investigate if exposure to Pandemrix® similarly increased the risk of islet autoimmunity or type 1 diabetes. Methods: In The Environmental Determinants of Diabetes in the Young (TEDDY) study, children are followed prospectively for the development of islet autoimmunity and type 1 diabetes. In October 2009, when the mass vaccination began, 3401 children at risk for islet autoimmunity and type 1 diabetes were followed in Sweden and Finland. Vaccinations were recorded and autoantibodies against insulin, GAD65 and insulinoma-associated protein 2 were ascertained quarterly before the age of 4 years and semi-annually thereafter. Results: By 5 August 2010, 2413 of the 3401 (71%) children observed as at risk for an islet autoantibody or type 1 diabetes on 1 October 2009 had been vaccinated with Pandemrix®. By 31 July 2016, 232 children had at least one islet autoantibody before 10 years of age, 148 had multiple islet autoantibodies and 96 had developed type 1 diabetes. The risk of islet autoimmunity was not increased among vaccinated children. The HR (95% CI) for the appearance of at least one islet autoantibody was 0.75 (0.55, 1.03), at least two autoantibodies was 0.85 (0.57, 1.26) and type 1 diabetes was 0.67 (0.42, 1.07). In Finland, but not in Sweden, vaccinated children had a lower risk of islet autoimmunity (0.47 [0.29, 0.75]), multiple autoantibodies (0.50 [0.28, 0.90]) and type 1 diabetes (0.38 [0.20, 0.72]) compared with those who did not receive Pandemrix®. The analyses were adjusted for confounding factors. Conclusions/interpretation: Children with an increased genetic risk for type 1 diabetes who received the Pandemrix® vaccine during the A/H1N1 2009 pandemic had no increased risk of islet autoimmunity, multiple islet autoantibodies or type 1 diabetes. In Finland, the vaccine was associated with a reduced risk of islet autoimmunity and type 1 diabetes.
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| 6. |
- Haghighi, Mona, et al.
(författare)
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A Comparison of Rule-based Analysis with Regression Methods in Understanding the Risk Factors for Study Withdrawal in a Pediatric Study
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Regression models are extensively used in many epidemiological studies to understand the linkage between specific outcomes of interest and their risk factors. However, regression models in general examine the average effects of the risk factors and ignore subgroups with different risk profiles. As a result, interventions are often geared towards the average member of the population, without consideration of the special health needs of different subgroups within the population. This paper demonstrates the value of using rule-based analysis methods that can identify subgroups with heterogeneous risk profiles in a population without imposing assumptions on the subgroups or method. The rules define the risk pattern of subsets of individuals by not only considering the interactions between the risk factors but also their ranges. We compared the rule-based analysis results with the results from a logistic regression model in The Environmental Determinants of Diabetes in the Young (TEDDY) study. Both methods detected a similar suite of risk factors, but the rule-based analysis was superior at detecting multiple interactions between the risk factors that characterize the subgroups. A further investigation of the particular characteristics of each subgroup may detect the special health needs of the subgroup and lead to tailored interventions.
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| 7. |
- Haller, Kristian
(författare)
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Acoustical Measurements of Material Nonlinearity and Nonequilibrium Recovery
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A damaged material or a material with non perfect atomic geometry, dislocations or cracks, exhibits two types of characteristic responses to acoustic excitations. First is the fast nonlinear dynamics response that is present as long as the material is excited. As soon as the excitation stops the response disappear. Second is the Slow Dynamics, which detects alterations of the material properties. The properties are affected by, for example, a mechanical pulse, changes in temperature, pressure or humidity. When the cause of alteration stops the material is recovering towards its equilibrium state. This recovering can exist over a long period of time, much longer than the vibration from a mechanical pulse. The techniques used here, both the fast and Slow Dynamics, have been used for NonDestructive Testing to detect damage in objects. All of them are suitable for this purpose, but for different material and geometry different techniques can be advantageous. They offer the possibility to use relatively low frequencies which is advantageous because attenuation and diffraction effects are smaller for low frequencies. Therefore large and multi-layered complete objects can be investigated. Sometimes the position of the damage is required, but it is in general difficult to limit the geometrical extent of low-frequency acoustic waves. A technique is presented that constrains the wave field to a localized trapped mode so that damage can be located. The existence of trapped modes is shown using an open resonator concept and the localization is shown to be successful. The problem with intermittent and changing amplitudes, even when very small, is that the material is really never at equilibrium, or even at steady state. The measurement signal influences the outcome. The material is affected by its strain history and its constantly changing state, the fast and Slow Dynamics are hard to separate. A measurement technique keeping the internal strain constant has been used to minimize the influence of Slow Dynamics allowing observations of only nonlinearity. The influence of temperature is also studied with this technique.
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| 8. |
- Haller, Kristian, et al.
(författare)
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Advantages of Nonlinear Wave Modulation Spectroscopy (NWMS) compared to some linear acoustic techniques
- 2003
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Konferensbidrag (refereegranskat)abstract
- This paper describes test results of a nonlinear wave modulation spectroscopy (NWMS) technique. These techniques are based on the strong connection between nonlinearity and presence of micro or macro-cracks. NWMS includes existence of higher harmonics, the presence of sidebands and ratio between excitation frequency and sideband components. Tests of different nonlinear techniques have been performed and compared to linear techniques. Tensile beams have been used as specimens. Piezoceramics were applied and a high frequency signal transmitted into the specimen simultaneously as a low frequency. Sideband around the high frequency and higher harmonics were then studied to detect nonlinearities. If there are cracks present, the NWMS show nonlinearities by combining the different frequencies shown as sidebands from the high frequency component, and the higher harmonics' amplitudes will increase. NWMS techniques are more sensitive than linear as they can detect smaller cracks. NWMS is faster to evaluate than a linear scanning method, as it can interrogate a complete object in just one measurement, and NWMS is not as limited by complicated geometry of the specimen.
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| 9. |
- Haller, Kristian, et al.
(författare)
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Constant Strain Frequency Sweep Measurements on Granite Rock
- 2008
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Ingår i: Physical Review Letters. - : The American Physical Society. - 0031-9007 .- 1079-7114. ; 100:6
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Tidskriftsartikel (refereegranskat)abstract
- Like many materials, granite exhibits both nonlinear acoustic distortion and slow nonequilibrium dynamics. Measurements to date have shown a response from both phenomena simultaneously, thus crosscontaminating the results. In this Letter, constant strain frequency sweep measurements eliminate the slow dynamics and, for the first time, permit evaluation of nonlinearity by itself characterized by lower resonance frequencies and a steeper slope. Measurements such as these are necessary for the fundamental understanding of material dynamics, and for the creation and validation of descriptive models.
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| 10. |
- Haller, Kristian, et al.
(författare)
-
Frequency sweep rate and amplitude influence on nonlinear acoustic measurements
- 2006
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Konferensbidrag (refereegranskat)abstract
- When subjecting a solid material to acoustic excitation with varying amplitude and sweep rate, the frequency shift response is not always behaving linear with amplitude. This phenomenon is connected to intricate nonlinear mechanics appearing in naturally imperfect materials and in damaged non-atomic solids. It is being investigated for different excitation amplitudes and for varying frequency sweep rates. This onset distribution can be mapped as an activation density.
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| 11. |
- Haller, Kristian, et al.
(författare)
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Method for Dynamic Automated Laser Measurement applied on Lightweight Test Panels
- 1999
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes an automated approach to modal testing utilizing a robot control to position a laser vibrometer beam. The method developed reduces the time-consuming data acquisition considerable. A double curved aluminium panel was chosen as test specimen. The selected specimen is suitable because it is hard to measure the dynamic properties of these kind of lightweight structures with accelerometers. Results from the experimental modal analysis were compared to the results given from the FEM calculations. An excellent agreement between the two models was found.
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| 12. |
- Haller, Kristian, et al.
(författare)
-
Method for Dynamic Automated Laser Measurement Applied on Lightweight Test Panels
- 1999
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Konferensbidrag (refereegranskat)abstract
- This paper describes an automated approach to modal testing utilizing a robot control to position a Laser Doppler Vibrometer (LVD) [1]. A programmed robotic system was used for the laser positioning. This kept the measurement set correctly identified with respect to the specimen geometry. The communication between the measurement program and the robot, the identification of the candidate robot system, and the mechanical design of the robot-vibrometer interface is described. For verification a sample measurement was performed and results are briefly presented.
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| 13. |
- Haller, Kristian
(författare)
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Nonlinear Acoustics Applied to NonDestructive Testing
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sensitive nonlinear acoustic methods are suitable for material characterization. This thesis describes three nonlinear acoustic methods that are proven useful for detection of defects like cracks and delaminations in solids. They offer the possibility to use relatively low frequencies which is advantageous because attenuation and diffraction effects are smaller for low frequencies. Therefore large and multi-layered complete objects can be investigated in about one second. Sometimes the position of the damage is required. But it is in general difficult to limit the geometrical extent of low-frequency acoustic waves. A technique is presented that constrains the wave field to a localized trapped mode so that damage can be located.
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| 14. |
- Haller, Kristian, et al.
(författare)
-
Nonlinear Ultrasonic Damage Response to Excitation Strength and Position
- 2006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A laminated carbon-fibre reinforced divinylcell plate is tested by a nonlinear ultrasonic technique for damage positioning. A high-frequency air-coupled transducer plate is placed above the plate surface, and a low-frequency contact source is fixed at one end. The high-frequency wave field fulfills the open resonator criteria making it localized inside the plate. The nonlinear damage response position is obtained by moving the high-frequency source on either side, having fixed sensors on both plate sides. Further, the nonlinear damage response is measured to change approximately linear with increase in high-frequency, or low-frequency, amplitude.
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| 15. |
- Haller, Kristian, et al.
(författare)
-
Slow variations of mechanical and electrical properties of dielectrics and nonlinear phenomena at ultrasonic irradiation
- 2010
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Ingår i: Acoustical Physics. - : Pleiades Publishing. - 1063-7710 .- 1562-6865. ; 56:5, s. 660-664
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Tidskriftsartikel (refereegranskat)abstract
- The interconnection between variations of elasticity and dielectric permittivity of mesoscopic solid systems under exposure to ultrasound is experimentally observed. A phenomenological theory generalizing Debye’s approach for polar fluids is developed to explain the measured data. The substitution of acoustic measurements by dielectric ones not only simplifies the procedure, but offers new possibilities to remotely evaluate the mechanical properties of materials and natural media.
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| 16. |
- Haller, Kristian, et al.
(författare)
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Sound Velocity Dependence on Strain for Damaged Steel
- 2008
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Konferensbidrag (refereegranskat)abstract
- When making acoustic measurements on materials with cracks, there exist two types of behavior that influence the sound velocity monitored through the resonance frequency of the object. One is the material's nonlinearity, and the other is a slow recovery process of the material parameters towards equilibrium called Slow Dynamics. The former is a wave distortion taking place in the presence of the wave while the latter is a slow recovery process that makes the time history of the material state count. For the understanding of the dynamics of these solids it is necessary to be able to separate the effects of nonlinearity and slow dynamics. In this work, this has been accomplished by making measurements on steel at steady-state through keeping the strain constant. Normal frequency sweeps at different strains are compared to constant strain sweeps. As every material state parameter can induce a slow dynamic response it is important to keep control of humidity and temperature. Measurements performed at different temperatures give different results. An example of this is the presented resonance frequency plots for the temperatures 20, 25 and 30 degrees Celcius. © 2008 American Institute of Physics.
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| 17. |
- Haller, Kristian, et al.
(författare)
-
Three Nonlinear NDE Techniques On Three Diverse Objects
- 2005
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Konferensbidrag (refereegranskat)abstract
- Non-Destructive Evaluation has been carried out on three different test objects, with three different methods based on exhibits of slow dynamics and nonlinear effects. The three diverse objects were cast iron, ceramic semi-conductors on circuit boards, and rubber. The three approaches were Higher Harmonics detection (HH), Nonlinear Wave Modulation Spectroscopy (NWMS), and Slow Dynamics (SD). For all of the objects the three approaches were tried. The results showed that for each of the objects, a different method worked the best. The cast iron worked best with nonlinear wave modulation, the ceramic semi-conductors worked well with the higher harmonics detection, while the rubber showed best results with slow dynamics.
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| 18. |
- Hedberg, Claes, et al.
(författare)
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A Self-Silenced Sound Beam
- 2010
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Ingår i: Acoustical Physics. - : Pleiades Publishing. - 1063-7710 .- 1562-6865. ; 56:5, s. 637-639
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Tidskriftsartikel (refereegranskat)abstract
- Parametric loudspeakers are transmitting two high power ultrasound frequencies. During propagation through the air, nonlinear interaction creates a narrow sound beam at the difference frequency, similar to a light beam from a torch. In this work is added the physical phenomenon of propagation cancellation, leaving a limited region within which the sound can be heard—a 1 meter long cylinder with diameter 8 cm. It is equivalent to a torch which would only illuminate objects within 1 meter. The concept is demonstrated both in simulation and in experiment.
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| 19. |
- Hedberg, Claes, et al.
(författare)
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Deflection dynamics of rock beam caused by ultrasound
- 2013
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Ingår i: Mechanics of time-dependant materials. - : Springer. - 1385-2000 .- 1573-2738. ; 17:4, s. 597-604
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Tidskriftsartikel (refereegranskat)abstract
- A new method for monitoring the time dependent dynamics of materials is proposed and implemented. By completely separating the conditioning (here ultrasound), the probing (here gravity), and the material state indicator (here deflection), the details of this dynamic process becomes apparent. The method allows both continuous monitoring of the material state without cross-interaction by the measuring process on the results, as well as complete freedom of conditioning and probing. It was successfully tested for sensitivity and repeatability when applied on a horizontally suspended beam of gabbro rock, which was observed to sag when subjected to ultrasound. These introductory tests have given new insights. The beam rises back, against the force of gravity, after the ultrasound is turned off. The deflection motions are fast both at the onset and at the termination of ultrasound, with the subsequent continuations being much slower. This new method is able to provide the higher accuracy needed for the advancement of the theoretical framework for material property time dependent dynamics.
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| 20. |
- Hedberg, Claes, et al.
(författare)
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Design Alterations of a High Power Air Transducer
- 2007
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 46:7, s. 4908-4911
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Tidskriftsartikel (refereegranskat)abstract
- For certain resonant high-power air transducers exists a radiating cone which is in some way connected to a forcing piezoelectric ceramic. This study focuses purely on the cone structure itself, and the form of excitation that gives desired results on the vibration modes of the cone. In the new design three different parameters are changed from existing devices. They are: 1) the change of the round piezoelectric disc center position to a piezoelectric ring shape, while making the cone center fixed, 2) the cutting of the cone into leaves, and 3) the radial thickness decreasing with radius. In simulations, the new design yields considerably higher vibration amplitudes.
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| 21. |
- Hedberg, Claes, et al.
(författare)
-
Double open resonator for localized non-contact acoustic testing
- 2004
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Konferensbidrag (refereegranskat)abstract
- There exist two concepts of open resonators that can be combined into a device for acoustic non-destructive testing. The device is non-contact and based on the fact that an airgap between a transducer surface and the test object can be set into resonance. This occurs for the conditions that makes this an open resonator (open because the air volume is not closed), and the wave field is amplified so that a larger amplitude is reached at the object surface. Let us assume that the object is a plate. When the acoustic wave enters the plate, one can let the frequency be the resonant frequency for one of the modes for the plate thickness. A limited part of the plate may be seen as a resonator, open to the sides. When the conditions for an open resonator is fulfilled for the plate thickness, the wave field will be greatly amplified within a region close to the insonified plate surface, and thus the linear or nonlinear response from this excitation is local. The device may then be used to scan the plate for material parameter changes.
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| 22. |
- Hedberg, Claes, et al.
(författare)
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Method for Monitoring Slow Dynamics Recovery
- 2012
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Ingår i: Acoustical Physics. - : SP MAIK Nauka/Interperiodica. - 1063-7710 .- 1562-6865. ; 58:3, s. 713-717
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Tidskriftsartikel (refereegranskat)abstract
- Slow Dynamics is a specific material property, which for example is connected to the degree of damage. It is therefore of importance to be able to attain proper measurements of it. Usually it has been monitored by acoustic resonance methods which have very high sensitivity as such. However, because the acoustic wave is acting both as conditioner and as probe, the measurement is affecting the result which leads to a mixing of the fast nonlinear response to the excitation and the slow dynamics material recovery. In this article a method is introduced which, for the first time, removes the fast dynamics from the process and allows the behavior of the slow dynamics to be monitored by itself. The new method has the ability to measure at the shortest possible recovery times, and at very small conditioning strains. For the lowest strains the sound speed increases with strain, while at higher strains a linear decreasing dependence is observed. This is the first method and test that has been able to monitor the true material state recovery process.
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| 23. |
- Hedberg, Claes, et al.
(författare)
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Non-contact nonlinear acoustic damage localization in plates. Part 1 : Resonance of air between plates
- 2007
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Ingår i: Acta Acoustica united with Acustica. - : S HIRZEL VERLAG. - 1610-1928 .- 1861-9959. ; 93:1, s. 13-21
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Tidskriftsartikel (refereegranskat)abstract
- This is the first of three articles that deals with the goal of using non-contact nonlinear acoustic methods for the damage localization in plates. In this first part, the resonant air gap wave field between one active and one passive reflecting plate was investigated experimentally. Of particular interest is the wave field amplitude strength, and its distribution on the passive surface. The wave amplitude may be increased by choosing one plate to be concave, overcoming the nonlinear damping taking place for two flat plates. Applications are connected with an increased wave field having advantages for processes taking place under open conditions and for a non-contact transducers' efficiency of transferring energy into an object. A double resonance gives highest air pressure, while a triple provides most energy in the passive object. By choosing the gap distance, frequency and transducer width, the appearing resonant wave will have a considerably larger amplitude at the object surface. The work through the interface from air to object is investigated and the wave field in a resonant air-plate system is shown.
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| 24. |
- Hedberg, Claes, et al.
(författare)
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Non-contact nonlinear acoustic damage localization in plates. Part 2 : Localized resonance through dynamically trapped modes
- 2008
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Ingår i: Acta Acustica united with Acustica. - : S. Hirzel Verlag GmbH. - 1610-1928. ; 94:1, s. 48-53
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Tidskriftsartikel (refereegranskat)abstract
- This work is the second part of three that presents new tools to be used for damage localization in plates by nonlinear acoustical methods. It introduces an important in-plane localization technique, which is based on the existence of resonant spatially localized wave fields. The wave from the transducer is acting as a dynamic influence on the plate surface, making the waves reflect in a non-ideal way. The non-ideal reflections make the modes underneath the transducer have different resonant frequencies than the modes beside the insonified area. They appear both for contact and non-contact sources. In the nonlinear damage localization application, the trapped mode wave field interacts with another signal at lower frequency. This results in sidebands around the high frequency whose amplitudes are related to the amount of damage underneath the transducer.
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| 25. |
- Hedberg, Claes, et al.
(författare)
-
Non-contact nonlinear ultrasound scan of a CFRP plate with manufactured damages
- 2013
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Konferensbidrag (refereegranskat)abstract
- A Carbon Fibre Reinforced Plastic plate was manufactured to have internal damages of different types. A nonlinear ultrasound technique was used to scan the plate. Non-contact transmitters of own design were used as transducer, and a contact sensor was used to measure the wave in the composite. Scanning was made perpendicularly with the sensor being on the same side as the transducer. The technique can be adapted in accuracy and speed.
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| 26. |
- Hedberg, Claes, et al.
(författare)
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Ultrasonic monitoring of a fiber reinforced plastic : steel composite beam during fatigue
- 2012
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Ingår i: Proceedings of the 6th European Workshop - Structural Health Monitoring 2012, EWSHM 2012. - Dresden : German Society for Nondestructive Testing. ; , s. 1254-1260
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Konferensbidrag (refereegranskat)abstract
- The use of composite superstructures on current or newly built steel hulls is a recently emerged technology. The economic estimations predict that the extra costs for putting composite superstructures, with the present safety margins, on steel ships will be paid back in only 2-3 years. This also makes the ships having smaller ecological footprints with less fuel consumption and CO2 emissions. In this stage of development it is needed to ensure the durability of the joints between the steel and glass fiber reinforced plastic. The first step is that the joints must first be proven to withstand fatigue. In this test a 4-meter beam, which represents the joint, were investigated for fatigue progression by a four-point-bending fatigue test. In order to show that ultrasonic material monitoring techniques can be used to monitor the damage progression, the beam was measured during the tests until failure. The test was successful both in showing that the joint could withstand high levels of mechanical exposure, and in that the ultrasonic techniques accompanied the damage progression which means that they may be used on vessels during operation
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| 27. |
- Karlsson, Stefan, 1984-, et al.
(författare)
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Hållfasthetsklassificering av planglas för bättre kvalitet
- 2021
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Ingår i: GLAS. - : Glasbranschföreningen. ; :4, s. 60-61
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- I dagsläget finns endast förstörande metoder för att bestämma hållfastheten för planglas. Det har medfört att på grund av den stora spridningen i hållfasthet av planglas behöver man ta till en stor säkerhetsfaktor. En ”säker” designhållfasthet som med andra ord behöver vara så låg så att risken är minimal att glaset går sönder. Resultatet blir att onödigt mycket glas används eftersom glas i princip alltid är starkare än designhållfastheten. Dessutom finns det idag heller ingen metod som kan mäta att glaset faktiskt upprätthåller designhållfastheten. Det finns med andra många skäl, både miljömässiga och kvalitetsskäl, till att utveckla en icke-förstörande metod till att bestämma hållfastheten av planglas.
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| 28. |
- Karlsson, Stefan, et al.
(författare)
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Kvalitetshöjning av planglas : Icke-förstörande provning av glasets hållfasthet
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Hållfastheten och därmed kvaliteten på planglas varierar kraftigt beroende på förekomsten sprickor i glasets yta. Sprickorna fungerar som brottanvisningar vilket medför att man måste räkna med stora säkerhetsfaktorer då glas belastas i olika byggnadskonstruktioner. Trä som konstruktionsmaterial har en liknande problematik där man utvecklat virkessortering för att kvalitetsklassning. I den här förstudien har vi undersökt om det går att kvalitetsklassa planglas med hjälp av en oförstörande provningsmetod baserad på icke-linjärt ultraljud. Tre olika kantbearbetningar (A) dragen, (B) obehandlad och (C) polerad kant undersöktes i 4-punktsböjprovning med tre olika belastningshastigheter (0.6, 2 och 5mm/min) och kontinuerlig mätning av skadevärde med icke-linjärt ultraljud. Hållfastheten för de olika kantbearbetningar följer trenden (C) polerad > (A) dragen > (B) obehandlad med avtagande hållfasthet. Som förväntat gav provningarna ett ökande skadevärde med en ökande last. Provningarna visade även att hållfastheten var lägre för lägre belastningshastigheter. Skadevärdet ökade mest för obehandlad kant vilket tyder på att det fanns en stor spricktillväxt medan lägst ökning gav polerad kant. Vi har även undersökt obehandlade brutna kanter med optiskt profilometri och i ljusmikroskop. Med ljusmikroskopi kunde vi linjärt korrelera kantskadans tjocklek till tjockleken på glaset. Luftsidan på planglas undersöktes med optisk profilometri och man fann tydliga skillnader i ytornas karakteristik. Skillnaderna är inte synliga för blotta ögat men de skulle kunna ge upphov till andra skillnader såsom t ex fuktkänslighet, mekanisk skärbarhet och hållfasthet. Sammanfattningsvis så finns det god potential för kvalitetsklassning av planglas men det kommer att behövas fler tester i ett större forskningsprojekt för att ta detta till marknaden. Marknadspotentialen är enorm med 80 miljoner ton planglas i marknadsbehov.
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| 29. |
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| 30. |
- Karlsson, Stefan, 1984-, et al.
(författare)
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Strength classification of flat glass for better quality – validation of method by well-defined surface defects and strength testing
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The current project was a collaborative project between the involved partners: RISE Glass, Lund University and Acoustic Agree. It is funded by ÅForsk (Grant No. 19-479). The project is a follow-up project from a Smart Housing Småland (Grant No. 2016-04218) pre-study where we used a nonlinear acoustic wave (NAW) to determine the damage value in float glass simultaneously with four-point bending tests. Glass is a brittle material whose strength is primarily determined by its surface characteristics i.e., the presence of flaws, defects or cracks on the surface. The strength of glass is greatly limited by stress-concentrations at the crack tips generating very high stresses when the glass is under load. The size and distribution of surface defects vary greatly, this gives a great variation of strength of glasses so that conventionally very large safety measures must be employed for glass products. If these defects and/or cracks could be detected in a non-destructive way, it would be beneficial for glass manufacturers as well as final building users. Nonlinear acoustic wave (NAW) techniques can be used to detect defects in materials. In these methods, acoustic waves are transmitted through an object and nonlinear effects, caused by the defects in the material, is analysed from the signal obtained at the receiver. The aim of the current project was to establish a calibration and a clear correlation between nonlinear acoustic wave measurements and the ultimate strength of annealed glass samples with controlled defects. Controlled defects were made as indentation imprints with a microindenter, equipped with a Vickers diamond head, in the middle of float glass samples with the dimensions 4×100×100 mm3. The applied loads were 0.5N, 1N, 2N, 5N and 10N. The indents were inspected with a microscope in order to see the cracks and the depth of the indents were also determined. The formed defects (cracks) were detected with NAW technique. Analysing the waves after propagating in the glass the nonlinear content in the wave was analysed. Due to the objects damage, the propagated wave distorts proportionally to the damage. After the NAW-inspection the strength of the glass samples were tested with ring-on-ring tests. Using the results from NAW-inspection, a clear correlation between the nonlinear response and the indenter load was found. There was also an obvious correlation between the failure load on the ring-on-ring-tests and the indenter load. The standard deviation for the ring-on-ring-tests for the 1N, 2N, 5N and 10 N was low but for the 0.5 N load was very high. A possible explanation is that the indenter imprint in most of the cases only gave rise to plastic deformation and in some samples, cracks were formed too. There were visible cracks for all the higher indenter loads and thus a lower scatter of the results. The main conclusion of the project is that it is possible to detect small cracks, which cannot be seen with the naked eye, with NAW technique and it can be directly correlated to the strength of the glass.
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| 31. |
- Locke, Adam E, et al.
(författare)
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Genetic studies of body mass index yield new insights for obesity biology.
- 2015
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 518:7538, s. 197-401
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Tidskriftsartikel (refereegranskat)abstract
- Obesity is heritable and predisposes to many diseases. To understand the genetic basis of obesity better, here we conduct a genome-wide association study and Metabochip meta-analysis of body mass index (BMI), a measure commonly used to define obesity and assess adiposity, in up to 339,224 individuals. This analysis identifies 97 BMI-associated loci (P < 5 × 10(-8)), 56 of which are novel. Five loci demonstrate clear evidence of several independent association signals, and many loci have significant effects on other metabolic phenotypes. The 97 loci account for ∼2.7% of BMI variation, and genome-wide estimates suggest that common variation accounts for >20% of BMI variation. Pathway analyses provide strong support for a role of the central nervous system in obesity susceptibility and implicate new genes and pathways, including those related to synaptic function, glutamate signalling, insulin secretion/action, energy metabolism, lipid biology and adipogenesis.
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| 32. |
- Lundgren, Markus, et al.
(författare)
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Analgesic antipyretic use among young children in the TEDDY study : No association with islet autoimmunity
- 2017
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Ingår i: BMC Pediatrics. - : Springer Science and Business Media LLC. - 1471-2431. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The use of analgesic antipyretics (ANAP) in children have long been a matter of controversy. Data on their practical use on an individual level has, however, been scarce. There are indications of possible effects on glucose homeostasis and immune function related to the use of ANAP. The aim of this study was to analyze patterns of analgesic antipyretic use across the clinical centers of The Environmental Determinants of Diabetes in the Young (TEDDY) prospective cohort study and test if ANAP use was a risk factor for islet autoimmunity. Methods: Data were collected for 8542 children in the first 2.5 years of life. Incidence was analyzed using logistic regression with country and first child status as independent variables. Holm's procedure was used to adjust for multiplicity of intercountry comparisons. Time to autoantibody seroconversion was analyzed using a Cox proportional hazards model with cumulative analgesic use as primary time dependent covariate of interest. For each categorization, a generalized estimating equation (GEE) approach was used. Results: Higher prevalence of ANAP use was found in the U.S. (95.7%) and Sweden (94.8%) compared to Finland (78.1%) and Germany (80.2%). First-born children were more commonly given acetaminophen (OR 1.26; 95% CI 1.07, 1.49; p = 0.007) but less commonly Non-Steroidal Anti-inflammatory Drugs (NSAID) (OR 0.86; 95% CI 0.78, 0.95; p = 0.002). Acetaminophen and NSAID use in the absence of fever and infection was more prevalent in the U.S. (40.4%; 26.3% of doses) compared to Sweden, Finland and Germany (p < 0.001). Acetaminophen or NSAID use before age 2.5 years did not predict development of islet autoimmunity by age 6 years (HR 1.02, 95% CI 0.99-1.09; p = 0.27). In a sub-analysis, acetaminophen use in children with fever weakly predicted development of islet autoimmunity by age 3 years (HR 1.05; 95% CI 1.01-1.09; p = 0.024). Conclusions: ANAP use in young children is not a risk factor for seroconversion by age 6 years. Use of ANAP is widespread in young children, and significantly higher in the U.S. compared to other study sites, where use is common also in absence of fever and infection.
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| 33. |
- Lynch, Kristian F., et al.
(författare)
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Gestational respiratory infections interacting with offspring HLA and CTLA-4 modifies incident β-cell autoantibodies
- 2018
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Ingår i: Journal of Autoimmunity. - : Elsevier BV. - 0896-8411. ; 86, s. 93-103
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Tidskriftsartikel (refereegranskat)abstract
- β-cell autoantibodies against insulin (IAA), GAD65 (GADA) and IA-2 (IA-2A) precede onset of childhood type 1 diabetes (T1D). Incidence of the first appearing β-cell autoantibodies peaks at a young age and is patterned by T1D-associated genes, suggesting an early environmental influence. Here, we tested if gestational infections and interactions with child's human leukocyte antigen (HLA) and non-HLA genes affected the appearance of the first β-cell autoantibody. Singletons of mothers without diabetes (n = 7472) with T1D-associated HLA-DR-DQ genotypes were prospectively followed quarterly through the first 4 years of life, then semiannually until age 6 years, using standardized autoantibody analyses. Maternal infections during pregnancy were assessed via questionnaire 3-4.5 months post-delivery. Polymorphisms in twelve non-HLA genes associated with the first appearing β-cell autoantibodies were included in a Cox regression analysis. IAA predominated as the first appearing β-cell autoantibody in younger children (n = 226, median age at seroconversion 1.8 years) and GADA (n = 212; 3.2 years) in children aged ≥2 years. Gestational infections were not associated with the first appearing β-cell autoantibodies overall. However, gestational respiratory infections (G-RI) showed a consistent protective influence on IAA (HR 0.64, 95% CI 0.45-0.91) among CTLA4-(AG, GG) children (G-RI*. CTLA4 interaction, p = 0.002). The predominant associations of HLA-DR-DQ 4-8/8-4 with IAA and HLA-DR-DQ 3-2/3-2 with GADA were not observed if a G-RI was reported (G-RI*HLA-DR-DQ interaction, p = 0.03). The role of G-RI may depend on offspring HLA and CTLA-4 alleles and supports a bidirectional trigger for IAA or GADA as a first appearing β-cell autoantibody in early life.
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| 34. |
- Olsson, Ulrika, et al.
(författare)
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Dynamic Automated Measurement on Light Weight Test Panels
- 1999
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Konferensbidrag (refereegranskat)abstract
- This paper describes an automated approach to modal testing utilizing a robot control to position a Laser Doppler Vibrometer (LDV) beam. The LDV measures the velocity response of test panels to a broad band force excitation. The implementation of the laser beam approach involves moving the beam once for each member of the velocity-force set. It is critical that the beam is positioned precisely, and the measurement set is correctly correlated to the specimen geometry. A programmed robotic system was used for the laser positioning and for keeping the measurement set correctly identified with respect to the specimen geometry. The result clearly shows the possibility to automate time consuming modal measurement of lightweight structures by utilizing a robot to control a LDV.
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| 35. |
- Perez Caro, Lluis, et al.
(författare)
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Damage and fracture during sheet-metal forming of alloy 718
- 2019
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Ingår i: International Journal of Material Forming. - : Springer Science and Business Media LLC. - 1960-6206 .- 1960-6214. ; 13:1, s. 15-28
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Tidskriftsartikel (refereegranskat)abstract
- Forming nickel-based superalloy aero-engine components is a challenging process, largely because of the risk of high degree of springback and issues with formability. In the forming tests conducted on alloy 718 at room temperature, open fractures are observed in the drawbead regions, which are not predicted while evaluating the formability using the traditional forming-limit diagram (FLD). This highlights the importance of an accurate prediction of failure during forming as, in some cases, may severely influence the springback and thereby the accuracy of the predicted shape distortions, leading the final shape of the formed component out of tolerance. In this study, the generalised incremental stress-state dependent damage model (GISSMO) is coupled with the isotropic von Mises and the anisotropic Barlat Yld2000-2D yield criteria to predict the material failure in the forming simulations conducted on alloy 718 using LS-DYNA. Their effect on the predicted effective plastic strains and shape deviations is discussed. The failure and instability strains needed to calibrate the GISSMO are directly obtained from digital image correlation (DIC) measurements in four different specimen geometries i.e. tensile, plane strain, shear, and biaxial. The damage distribution over the drawbeads is measured using a non-linear acoustic technique for validation purposes. The numerical simulations accurately predict failure at the same regions as those observed in the experimental forming tests. The expected distribution of the damage over the drawbeads is in accordance with the experimental measurements. The results highlight the potential of considering DIC to calibrate the GISSMO in combination with an anisotropic material model for forming simulations in alloy 718.
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| 36. |
- Persson, Kent, et al.
(författare)
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Non-destructive testing of the strength of glass by a non-linear ultrasonic method
- 2020
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Ingår i: Challenging Glass Conference Proceedings. - 9789463662963
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Konferensbidrag (refereegranskat)abstract
- The paper presents basis and experimental results of a non-destructive method aimed at determination of the presence of large surface cracks in glass samples by measurements with NAW® technology (Nonlinear Acoustic Wave). The method is based on a transmitted ultrasonic wave in the material from which the non-linear content of the signal can be analysed. A sample containing defects presents nonlinearities in the form of distortions, such as, higher order harmonics that are detected. Nonlinearities in the signal are primarily formed at crack-tips and the number of nonlinearities is proportional to the amount of damage, or defects, in the sample that is investigated. The result of the measurement and evaluation, that only takes a few seconds, is a damage value that is easy to understand and to use for immediate application. A number of preliminary test results and comparisons with destructive testing for various test setups, as well as a recent test strategy including fabricated defects with a nanoindenter will be discussed.
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| 37. |
- Shungin, Dmitry, et al.
(författare)
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New genetic loci link adipose and insulin biology to body fat distribution.
- 2015
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 518:7538, s. 187-378
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Tidskriftsartikel (refereegranskat)abstract
- Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms.
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