| 11. |
- Chen, WenChuang, et al.
(författare)
-
Numerical modelling of a point-absorbing wave energy converter in irregular and extreme waves
- 2017
-
Ingår i: Applied Ocean Research. - : Elsevier BV. - 0141-1187 .- 1879-1549. ; 63, s. 90-105
-
Tidskriftsartikel (refereegranskat)abstract
- Based on the Navier-Stokes (RANS) equations, a three-dimensional (3-D) mathematical model for the hydrodynamics and structural dynamics of a floating point-absorbing wave energy converter (WEC) with a stroke control system in irregular and extreme waves is presented. The model is validated by a comparison of the numerical results with the wave tank experiment results of other researchers. The validated model is then utilized to examine the effect of wave height on structure displacements and connection rope tension. In the examined cases, the differences in WEC’s performance exhibited by an inviscid fluid and a viscous fluid can be neglected. Our results also reveal that the differences in behavior predicted by boundary element method (BEM) and the RANS-based method can be significant and vary considerably, depending on wave height.
|
|
| 12. |
- Hulsart Billström, Gry, 1982-
(författare)
-
Bone Regeneration with Cell-free Injectable Scaffolds
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bone is a remarkable multifunctional tissue with the ability to regenerate and remodel without generating any scar tissue. However, bone loss due to injury or diseases can be a great challenge and affect the patient significantly. Autologous bone grafting is commonly used throughout the world. Autograft both fills the void and is bone inductive, housing the particular cells that are needed for bone regeneration. However, a regenerative complement to autograft is of great interest as the use of biomaterials loaded with bioactive molecules can avoid donor site morbidity and the problem of a limited volume of material. Two such regenerative products that utilise bone morphogenetic protein (BMP)-7 and -2 have been used for more than a decade clinically. Unfortunately, several side effects have been reported, such as severe swelling due to inflammation and ectopic bone formation. Additionally, the products require open surgery and use of supra physiological doses of the BMPs due to poor localisation and retention of the growth factor. The purpose of this thesis was to harness the strong inductive capacity of the BMP-2 by optimising the carrier of this bioactive protein, thereby minimising the side effects that are associated with the clinical products and facilitating safe and localised bone regeneration. We focused on an injectable hyaluronan-based carrier developed through polymer chemistry at the University of Uppsala. The strategy was to use the body’s own regenerative pathway to stimulate and enhance bone healing in a manner similar to the natural bone-healing process. The hyaluronan-based carrier has a similar composition to the natural extracellular matrix and is degraded by resident enzymes. Earlier studies have shown improved properties when adding hydroxyapatite, a calcium phosphate that constitutes the inorganic part of the bone matrix. In Paper I, the aim was to improve the carrier by adding other forms of calcium phosphate. The results indicated that bone formation was enhanced when using nano-sized hydroxyapatite. In Paper II, we discovered the importance of crushing the material, thus enhancing permeability and enlarging the surface area. We wished to further develop the carrier system, but were lacking an animal model with relatively high throughput, facilitated access, paired data, and we were also committed to the 3Rs of refinement, reduction, and replacement. To meet these challenges, we developed and refined an animal model, and this is described in Paper III. In Paper IV, we sought to further optimise the biomaterial properties of the hydrogel through covalent bonding of bisphosphonates to the hyaluronan hydrogel. This resulted in exceptional retention of the growth factor BMP-2. In Paper V, SPECT/PET/µCT was combined as a tri-modal imaging method to allow visualisation of the biomaterial’s in situ action, in terms of drug retention, osteoblast activity and mineralisation. Finally, in Paper VI the correlation between existing in vitro results with in vivo outcomes was observed for an array of biomaterials. The study identified a surprisingly poor correlation between in vitro and in vivo assessment of biomaterials for osteogenesis.
|
|
| 13. |
- Sjökvist, Linnea, et al.
(författare)
-
Calculating Buoy Response for a Wave Energy Converter - a Comparsion Between Two Computational Methods and Experimental Results
- 2017
-
Ingår i: Theoretical and Applied Mechanics Letters. - : Elsevier BV. - 2095-0349. ; 7:3, s. 164-168
-
Tidskriftsartikel (refereegranskat)abstract
- When designing a wave power plant, reliable and fast simulation tools are required. Computational fluid dynamics (CFD) software provides high accuracy but with a very high computational cost, and in operational, moderate sea states, linear potential flow theories may be sufficient to model the hydrodynamics. In this paper, a model is built in COMSOL Multiphysics to solve for the hydrodynamic parameters of a point-absorbing wave energy device. The results are compared with a linear model where the hydrodynamical parameters are computed using WAMIT, and to experimental results from the Lysekil research site. The agreement with experimental data is good for both numerical models.
|
|
| 14. |
- Unneby, Anna, et al.
(författare)
-
Femoral nerve block in a representative sample of elderly people with hip fracture : a randomised controlled trial
- 2017
-
Ingår i: Injury. - : ELSEVIER SCI LTD. - 0020-1383 .- 1879-0267. ; 48:7, s. 1542-1549
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: The number of elderly people with hip fracture and dementia is increasing, and many of these patients suffer from pain. Opioids are difficult to adjust and side effects are common, especially with increased age and among patients with dementia. Preoperative femoral nerve block is an alternative pain treatment. Aim: To investigate whether preoperative femoral nerve block reduced acute pain and opioid use after hip fracture among elderly patients, including those with dementia. Patients and methods: In this randomised controlled trial involving patients aged >= 70 years with hip fracture (trochanteric and cervical), including those with dementia, we compared femoral nerve block with conventional pain management, with opioid use if required. The primary outcome was preoperative pain, measured at five timepoints using a visual analogue scale (VAS). Preoperative opioid consumption was also registered. Results: The study sample comprised 266 patients admitted consecutively to the Orthopaedic Ward. The mean age was 84.1 (+/- 6.9) years, 64% of participants were women, 44% lived in residential care facilities, and 120 (45.1%) had dementia diagnoses. Patients receiving femoral nerve block had significantly lower self-rated pain scores from baseline to 12 h after admission than did controls. Self-rated and proxy VAS pain scores decreased significantly in these patients from baseline to 12 h compared with controls (p < 0.001 and p = 0.003, respectively). Patients receiving femoral nerve block required less opioids than did controls, overall (2.3 +/- 4.0 vs. 5.7 +/- 5.2 mg, p < 0.001) and in the subgroup with dementia (2.1 +/- 3.3 vs. 5.8 +/- 5.0 mg, p < 0.001). Conclusion: Patients with hip fracture, including those with dementia, who received femoral nerve block had lower pain scores and required less opioids before surgery compared with those receiving conventional pain management. Femoral nerve block seems to be a feasible pain treatment for elderly people, including those with dementia.
|
|
| 15. |
- Li, Wei, et al.
(författare)
-
Bivariate joint distribution modeling of wave climate data using a copula method
- 2016
-
Ingår i: International Journal of Energy and Statistics. - World Scientific Publishing. - 2335-6812. ; 4:3
-
Tidskriftsartikel (refereegranskat)abstract
- The bivariate joint distribution of the significant wave height and the wave period is of great importance in characterizing the wave climate at a wave energy converter test site. In this paper, we investigate bivariate joint distribution modeling of the wave climate at the Lysekil wave energy converter test site off the Swedish west coast. This study is based on 9 years of wave observations at the test site from 2005 to 2013. Archimedean Copulas are used for the bivariate joint distribution modeling of the significant wave height and the wave period. Measured wave data is compared with simulated wave climate data for the Lysekil test site using three Archimedean Copula models, the Clayton, Frank and Gumbel copulas. The R-squared statistical test yields a better goodness of fit for the Gumbel copula compared to the other two copulas. In addition, the Archimedean Copula method is applied to the measured wave climate data from two other sites to illustrate the general applicability. It shows that the Archimedean Copulas exhibits stable performance with good accuracy in characterizing the wave climate and they can be employed for forecasting the wave energy resource and assessing the survivability of wave energy converters.
|
|
| 16. |
- Li, Wei, et al.
(författare)
-
Statistical Analysis of Wave Climate Data Using Mixed Distributions and Extreme Wave Prediction
- 2016
-
Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 9:6
-
Tidskriftsartikel (refereegranskat)abstract
- The investigation of various aspects of the wave climate at a wave energy test site is essential for the development of reliable and efficient wave energy conversion technology. This paper presents studies of the wave climate based on nine years of wave observations from the 2005-2013 period measured with a wave measurement buoy at the Lysekil wave energy test site located off the west coast of Sweden. A detailed analysis of the wave statistics is investigated to reveal the characteristics of the wave climate at this specific test site. The long-term extreme waves are estimated from applying the Peak over Threshold (POT) method on the measured wave data. The significant wave height and the maximum wave height at the test site for different return periods are also compared. In this study, a new approach using a mixed-distribution model is proposed to describe the long-term behavior of the significant wave height and it shows an impressive goodness of fit to wave data from the test site. The mixed-distribution model is also applied to measured wave data from four other sites and it provides an illustration of the general applicability of the proposed model. The methodologies used in this paper can be applied to general wave climate analysis of wave energy test sites to estimate extreme waves for the survivability assessment of wave energy converters and characterize the long wave climate to forecast the wave energy resource of the test sites and the energy production of the wave energy converters.
|
|
| 17. |
- Röding, Fredrik, et al.
(författare)
-
Trauma recidivism at an emergency department of a Swedish medical center
- 2016
-
Ingår i: Injury Epidemiology. - : Springer Science and Business Media LLC. - 2197-1714. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: To inform targeted prevention, we studied patterns of trauma recidivism and whether a first injury predicts the risk for a recurrent injury.METHODS: In a population-based study of 98,502 adult injury events 1999-2012, at the emergency department of Umeå University Hospital, Sweden, we compared non-recidivists with recidivists in terms of patients' sex, age, type of injury and severity of the injury.RESULTS: Thirty-six percent of all patients suffered recurrent injuries, which were associated with a higher proportion of inpatient care and more hospital days. Young men and elderly women were at the highest risk for trauma recidivism. At 20 to 24 years, men had a 2.4 (CI 95 % 2.3-2.5) higher risk than women, a 90 years old woman had almost a 10-fold higher risk for another moderate/severe injury than a 20 years old one. A fracture were associated with a hazard ratio of 1.28 (CI 95 % 1.15-1.42) among men younger than 65 years and 1.31 (CI 95 % 1.12-1.54) for men older than 65 years for a subsequent moderate/severe injury. For women younger than 65 years a fracture was associated with a hazard ratio of 1.44 (CI 95 % 1.28-1.62) for a subsequent moderate/severe injury. A sprain carries a higher risk for a new moderate/severe injury for both men and women and in both age groups; the hazard ratio was 1.13 (CI 95 % 1.00-1.26) for men younger than 65 years, 1.42 (CI 95 % 1.01-1.99) for men older than 65 years, 1.19 (CI 95 % 1.05-1.35) for women younger than 65 years and 1.26 (CI 95 % 1.02-1.56) for women older than 65 years. A higher degree of injury severity was associated with a higher risk for a new moderate/severe injury.CONCLUSION: Trauma recidivism is common and represents a large proportion of all injured. Age and sex are associated with the risk for new injury. Injury types and severity, also have implications for future injury.
|
|
| 18. |
- Hai, Ling, et al.
(författare)
-
Modelling a point absorbing wave energy converter by the equivalent electric circuit theory : A feasibility study
- 2015
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 117
-
Tidskriftsartikel (refereegranskat)abstract
- There is a need to have a reliable tool to quickly assess wave energy converters (WECs). This paper explores whether it is possible to apply the equivalent electric circuit theory as an evaluation tool for point absorbing WEC system modelling. The circuits were developed starting from the force analysis, in which the hydrodynamic, mechanical, and electrical parameters were expressed by electrical components. A methodology on how to determine the parameters for electrical components has been explained. It is found that by using a multimeter, forces in the connection line and the absorbed electric power can be simulated and read directly from the electric circuit model. Finally, the circuit model has been validated against the full scale offshore experiment. The results indicated that the captured power could be predicted rather accurately and the line force could be estimated accurately near the designed working condition of the WEC.
|
|
| 19. |
- Parwal, Arvind, et al.
(författare)
-
Wave Energy Research at Uppsala University and The Lysekil Research Site, Sweden : A Status Update
- 2015
-
Konferensbidrag (refereegranskat)abstract
- This paper provides a summarized status update ofthe Lysekil wave power project. The Lysekil project is coordinatedby the Div. of Electricity, Uppsala University since 2002, with theobjective to develop full-scale wave power converters (WEC). Theconcept is based on a linear synchronous generator (anchored tothe seabed) driven by a heaving point absorber. This WEC has nogearbox or other mechanical or hydraulic conversion systems,resulting in a simpler and robust power plant. Since 2006, 12 suchWECs have been build and tested at the research site located atthe west coast of Sweden. The last update includes a new andextended project permit, deployment of a new marine substation,tests of several concepts of heaving buoys, grid connection,improved measuring station, improved modelling of wave powerfarms, implementation of remote operated vehicles forunderwater cable connection, and comprehensive environmentalmonitoring studies.
|
|
| 20. |
- Zheng, Hou-Feng, et al.
(författare)
-
Whole-genome sequencing identifies EN1 as a determinant of bone density and fracture
- 2015
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 526:7571, s. 112-
-
Tidskriftsartikel (refereegranskat)abstract
- The extent to which low-frequency (minor allele frequency (MAF) between 1-5%) and rare (MAF <= 1%) variants contribute to complex traits and disease in the general population is mainly unknown. Bone mineral density (BMD) is highly heritable, a major predictor of osteoporotic fractures, and has been previously associated with common genetic variants(1-8), as well as rare, population specific, coding variants(9). Here we identify novel non-coding genetic variants with large effects on BMD (n(total) = 53,236) and fracture (n(total) = 508,253) in individuals of European ancestry from the general population. Associations for BMD were derived from whole-genome sequencing (n = 2,882 from UK10K (ref. 10); a population-based genome sequencing consortium), whole-exome sequencing (n = 3,549), deep imputation of genotyped samples using a combined UK10K/1000 Genomes reference panel (n = 26,534), and de novo replication genotyping (n = 20,271). We identified a low-frequency non-coding variant near a novel locus, EN1, with an effect size fourfold larger than the mean of previously reported common variants for lumbar spine BMD8 (rs11692564(T), MAF51.6%, replication effect size510.20 s.d., P-meta = 2 x 10(-14)), which was also associated with a decreased risk of fracture (odds ratio = 0.85; P = 2 x 10(-11); ncases = 98,742 and ncontrols = 409,511). Using an En1cre/flox mouse model, we observed that conditional loss of En1 results in low bone mass, probably as a consequence of high bone turnover. We also identified a novel low frequency non-coding variant with large effects on BMD near WNT16 (rs148771817(T), MAF = 1.2%, replication effect size +10.41 s.d., P-meta = 1 x 10(-11)). In general, there was an excess of association signals arising from deleterious coding and conserved non-coding variants. These findings provide evidence that low-frequency non-coding variants have large effects on BMD and fracture, thereby providing rationale for whole-genome sequencing and improved imputation reference panels to study the genetic architecture of complex traits and disease in the general population.
|
|
