| 1. |
- Adachi, Jonathan D., et al.
(författare)
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Impact of Prevalent Fractures on Quality of Life: Baseline Results From the Global Longitudinal Study of Osteoporosis in Women
- 2010
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Ingår i: Mayo Clinic proceedings. - : Elsevier BV. - 0025-6196 .- 1942-5546. ; 85:9, s. 806-813
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To examine several dimensions of health-related quality of life (HRQL) in postmenopausal women who report previous fractures, and to provide perspective by comparing these findings with those in other chronic conditions (diabetes, arthritis, lung disease).PATIENTS AND METHODS: Fractures are a major cause of morbidity among older women. Few studies have examined HRQL In women who have had prior fractures and the effect of prior fracture location on HRQL. In this observational study of 57,141 postmenopausal women aged 55 years and older (enrollment from December 2007 to March 2009) from 17 study sites in 10 countries, HRQL was measured using the European Quality of Life 5 Dimensions Index (EQ-5D) and the health status, physical function, and vitality questions of the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36).RESULTS: Reductions in EQ-5D health-utility scores and SF-36 measured health status, physical function, and vitality were seen in association with 9 of 10 fracture locations. Spine, hip, and upper leg fractures resulted in the greatest reductions In quality of life (EQ-5D scores, 0.62, 0.64, and 0.61, respectively, vs 0.79 without prior fracture). Women with fractures at any of these 3 locations, as well as women with a history of multiple fractures (EQ-5D scores, 0.74 for 1 prior fracture, 0.68 for 2, and 0.58 for >= 3), had reductions in HRQL that were similar to or worse than those in women with other chronic diseases (0.67 for diabetes, 0.69 for arthritis, and 0.71 for lung disease).CONCLUSION: Previous fractures at a variety of bone locations, particularly spine, hip, and upper leg, or involving more than 1 location are associated with significant reductions in quality of life.
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| 2. |
- Agnelli, Filippo, et al.
(författare)
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Design and testing of 3D-printed micro-architectured polymer materials exhibiting a negative Poisson’s ratio
- 2020
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Ingår i: Continuum Mechanics and Thermodynamics. - : Springer-Verlag New York. - 0935-1175 .- 1432-0959. ; 32:2, s. 433-449
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Tidskriftsartikel (refereegranskat)abstract
- This work proposes the complete design cycle for several auxetic materials where the cycle consists of three steps (i) the design of the micro-architecture, (ii) the manufacturing of the material and (iii) the testing of the material. We use topology optimization via a level-set method and asymptotic homogenization to obtain periodic micro-architectured materials with a prescribed effective elasticity tensor and Poisson’s ratio. The space of admissible micro-architectural shapes that carries orthotropic material symmetry allows to attain shapes with an effective Poisson’s ratio below −1−1. Moreover, the specimens were manufactured using a commercial stereolithography Ember printer and are mechanically tested. The observed displacement and strain fields during tensile testing obtained by digital image correlation match the predictions from the finite element simulations and demonstrate the efficiency of the design cycle.
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| 3. |
- Agnelli, Filippo, et al.
(författare)
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Design of thin micro-architectured panels with extension–bending coupling effects using topology optimization
- 2022
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Ingår i: Computer Methods in Applied Mechanics and Engineering. - : Elsevier. - 0045-7825 .- 1879-2138. ; 391
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Tidskriftsartikel (refereegranskat)abstract
- We design the micro-architecture of thin elastic panels to control their macroscopic behavior, accounting simultaneously for in-plane stiffness, out-of-plane stiffness and the extension–bending coupling effects. Our topology optimization method combines inverse homogenization, the Hadamard shape derivative and a level set method in the diffuse interface context to systematically capture within the unit cell the optimal micro-architecture. The efficiency of the solution method is illustrated through four numerical examples where the designed shape yields an important extension–bending coupling. The deformation responses under tensile loading are assessed numerically both on the complete periodic panel and on its homogenized twin plate. The results demonstrate that the simultaneous control of the in-plane, out-of-plane and their coupled behavior enables to shift a flat panel into a dome or a saddle shaped structure. Moreover, the obtained unit cells are elementary blocks to create directly 3D printable objects with shape-morphing capabilities.
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| 4. |
- Díez-Pérez, Adolfo, et al.
(författare)
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Regional differences in treatment for osteoporosis. The Global Longitudinal Study of Osteoporosis in Women (GLOW)
- 2011
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Ingår i: Bone. - : Elsevier. - 8756-3282 .- 1873-2763. ; 49:3, s. 493-498
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Tidskriftsartikel (refereegranskat)abstract
- PurposeTo determine if important geographic differences exist in treatment rates for osteoporosis and whether this variation can be explained by regional variation in risk factors.MethodsThe Global Longitudinal Study of Osteoporosis in Women is an observational study of women ≥ 55 years sampled from primary care practices in 10 countries. Self-administered questionnaires were used to collect data on patient characteristics, risk factors for fracture, previous fractures, anti-osteoporosis medication, and health status.ResultsAmong 58,009 women, current anti-osteoporosis medication use was lowest in Northern Europe (16%) and highest in USA and Australia (32%). Between 48% (USA, Southern Europe) and 68% (Northern Europe) of women aged ≥ 65 years with a history of spine or hip fracture since age 45 were untreated. Among women with osteoporosis, the percentage of treated cases was lowest in Europe (45–52% versus 62–65% elsewhere). Women with osteopenia and no other risk factors were treated with anti-osteoporosis medication most frequently in USA (31%) and Canada (31%), and least frequently in Southern Europe (12%), Northern Europe (13%), and Australia (16%). After adjusting for risk factors, US women were threefold as likely to be treated with anti-osteoporosis medication as Northern European women (odds ratio 2.8; 95% confidence interval 2.5–3.1) and 1.5 times as likely to be treated as Southern European women (1.5, 1.4–1.6). Up to half of women reporting previous hip or spine fracture did not receive treatment.ConclusionsThe likelihood of being treated for osteoporosis differed between regions, and cannot be explained by variation in risk factors. Many women at risk of fracture do not receive prophylaxis.
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| 5. |
- Fuhrmann, Jürgen, et al.
(författare)
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Unipolar Drift-Diffusion Simulation of S-Shaped Current-Voltage Relations for Organic Semiconductor Devices
- 2020
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Ingår i: Finite Volumes for Complex Applications IX - Methods, Theoretical Aspects, Examples. FVCA 2020. - Cham : Springer. - 9783030436506 - 9783030436513 ; , s. 625-633
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Bokkapitel (refereegranskat)abstract
- We discretize a unipolar electrothermal drift-diffusion model for organic semiconductor devices with Gauss–Fermi statistics and charge carrier mobilities having positive temperature feedback. We apply temperature dependent Ohmic contact boundary conditions for the electrostatic potential and use a finite volume based generalized Scharfetter-Gummel scheme. Applying path-following techniques we demonstrate that the model exhibits S-shaped current-voltage curves with regions of negative differential resistance, only recently observed experimentally.
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| 6. |
- Glitzky, Annegret, et al.
(författare)
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A coarse‐grained electrothermal model for organic semiconductor devices
- 2022
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Ingår i: Mathematical methods in the applied sciences. - : John Wiley & Sons. - 0170-4214 .- 1099-1476.
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Tidskriftsartikel (refereegranskat)abstract
- We derive a coarse-grained model for the electrothermal interaction of organic semiconductors. The model combines stationary drift-diffusion- based electrothermal models with thermistor-type models on subregions of the device and suitable transmission conditions. Moreover, we prove existence of a solution using a regularization argument and Schauder's fixed point theorem. In doing so, we extend recent work by taking into account the statistical relation given by the Gauss–Fermi integral and mobility functions depending on the temperature, charge-carrier density, and field strength, which is required for a proper description of organic devices.
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| 7. |
- Glitzky, Annegret, et al.
(författare)
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A hybrid model for the electrothermal behavior of semiconductor devices
- 2021
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Ingår i: Proceedings in Applied Mathematics and Mechanics. - : Wiley-Blackwell. - 1617-7061. ; 20:1, s. 1-2
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a hybrid model for the electro-thermal behavior of semiconductor heterostructures. It combines a model based on drift-diffusion with thermistor type models in different subregions of the semiconductor device. The aim of this hybrid modeling approach is to be physically as accurate as necessary and at the same time as computationally efficient as possible. Our existence proof uses a regularization method, a priori estimates, and Schauder's fixed point theorem.
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| 8. |
- Glitzky, Annegret, et al.
(författare)
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An existence result for a class of electrothermal drift-diffusion models with Gauss–Fermi statistics for organic semiconductors
- 2020
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Ingår i: Analysis and Applications. - : World Scientific. - 0219-5305 .- 1793-6861. ; 19:02, s. 275-304
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Tidskriftsartikel (refereegranskat)abstract
- This work is concerned with the analysis of a drift-diffusion model for the electrothermal behavior of organic semiconductor devices. A “generalized Van Roosbroeck” system coupled to the heat equation is employed, where the former consists of continuity equations for electrons and holes and a Poisson equation for the electrostatic potential, and the latter features source terms containing Joule heat contributions and recombination heat. Special features of organic semiconductors like Gauss–Fermi statistics and mobility functions depending on the electric field strength are taken into account. We prove the existence of solutions for the stationary problem by an iteration scheme and Schauder’s fixed point theorem. The underlying solution concept is related to weak solutions of the Van Roosbroeck system and entropy solutions of the heat equation. Additionally, for data compatible with thermodynamic equilibrium, the uniqueness of the solution is verified. It was recently shown that self-heating significantly influences the electronic properties of organic semiconductor devices. Therefore, modeling the coupled electric and thermal responses of organic semiconductors is essential for predicting the effects of temperature on the overall behavior of the device. This work puts the electrothermal drift-diffusion model for organic semiconductors on a sound analytical basis.
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| 9. |
- Glitzky, Annegret, et al.
(författare)
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Analysis of a bulk-surface thermistor model for large-area organic LEDs
- 2021
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Ingår i: Portugaliae Mathematica. - : European Mathematical Society Publishing House. - 0032-5155 .- 1662-2758. ; 78:2, s. 187-210
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Tidskriftsartikel (refereegranskat)abstract
- The existence of a weak solution for an effective system of partial differential equations describing the electrothermal behavior of large-area organic light-emitting diodes (OLEDs) is proved. The effective system consists of the heat equation in the threedimensional bulk glass substrate and two semilinear equations for the current flow through the electrodes coupled to algebraic equations for the continuity of the electrical fluxes through the organic layers. The electrical problem is formulated on the (curvilinear) surface of the glass substrate where the OLED is mounted. The source terms in the heat equation are due to Joule heating and are hence concentrated on the part of the boundary where the current-flow equation is posed. The existence of weak solutions to the effective system is proved via Schauder’s fixed-point theorem. Moreover, since the heat sources are a priori only in $L^1$, the concept of entropy solutions is used.
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| 10. |
- Glitzky, Annegret, et al.
(författare)
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Analysis of a hybrid model for the electro-thermal behavior of semiconductor heterostructures
- 2022
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Ingår i: Journal of Mathematical Analysis and Applications. - : Elsevier. - 0022-247X .- 1096-0813. ; 507:2
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Tidskriftsartikel (refereegranskat)abstract
- We prove existence of a weak solution for a hybrid model for the electro-thermal behavior of semiconductor heterostructures. This hybrid model combines an electro-thermal model based on drift-diffusion with thermistor type models in different subregions of the semiconductor heterostructure. The proof uses a regularization method and Schauder's fixed point theorem. For boundary data compatible with thermodynamic equilibrium we verify, additionally, uniqueness. Moreover, we derive bounds and higher integrability properties for the electrostatic potential and the quasi Fermi potentials as well as the temperature.
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