| 1. |
- Andersson, Per, et al.
(författare)
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The Configuration Of Actors In Market Practice
- 2009
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Ingår i: Marketing Theory. - : SAGE Publications (UK and US). - 1741-301X .- 1470-5931. ; 8:1, s. 67-90
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses three conceptual challenges concerning actors and agency that arise when taking interest in market practice: i) how agency is awarded in practical situations, ii) how actors are preconfigured, and iii) how actors are represented. These issues are explored in three empirical scenes taken from a case study of the introduction of an e-procurement system at an international transport and logistics company. First, we suggest that practical interaction can be fruitfully regarded as a process of interdefinition involving prescriptions and subscriptions between acting entities, or actants . Second, we employ the term inscription to address efforts to affect in advance the configuration of such actants. Third, we suggest that actors are entities to which actions are ascribed, ex post . Through this secondary process a number of actants may be subsumed under a common actor label, thus offering a way of accounting for agency as part of a practice perspective. We conclude by discussing implications of the proposed vocabulary for multiplicity, reflexivity and market agency.
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| 2. |
- Aspenberg, P., et al.
(författare)
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Drug test chamber : a titanium implant for administration of biochemical agents to a standardized bone callus in situ
- 1988
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Ingår i: Journal of Biomedical Engineering. - : Elsevier BV. - 0141-5425. ; 10:1, s. 70-73
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Tidskriftsartikel (refereegranskat)abstract
- A titanium implant in which a conduit is gradually filled with ingrowing bone (the Bone Harvest Chamber) has been modified to allow continuous local treatment of the conduit tissue with biochemical agents. Implants were inserted bilaterally in rabbit tibiae. The tissue content of the bone ingrowth conduits was studied with histology, 99mTc-MDP scintimetry and measurements of total calcium content. Bone was formed in the conduit by endochondral formation starting at both ends and continuing until fusion in the middle. After 2 weeks the bone had not yet met in the middle where fibrous tissue was seen. In eight animals 3H-proline was applied via one of the chambers, with the contralateral chamber as a saline-treated control. The collagen of the harvested tissue from the 3H-proline treated side had a 3H-hydroxyproline content 1000 times greater than had the control side. The 'drug test chamber' makes possible the study of local effects of drugs on healing of mature bone in vivo.
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| 3. |
- Aspenberg, P., et al.
(författare)
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Failure of bone induction by bone matrix in adult monkeys
- 1988
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Ingår i: Journal of Bone and Joint Surgery: British Volume. - 0301-620X. ; 70:4, s. 625-627
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Tidskriftsartikel (refereegranskat)abstract
- Extraskeletal bone formation can be induced in rodents by implantation of demineralised bone matrix and such implantation has been used to treat bone defects in man, but it is uncertain if induction or merely conduction occurs. We studied bone induction in primates by excising segments of the fibulae of adult squirrel monkeys, defatting and demineralising them before reimplanting them into the quadriceps of the same animal. As a control experiment, rat matrix was prepared in exactly the same way and implanted in rats. After six weeks the implants were harvested and either ashed and analysed for calcium content or prepared for histology. In the rats, the calcium content indicated that about 20% of the original matrix had been replaced by new bone. In the monkeys the calcium content was about the same as that in normal body fluid and no bone was seen in histological sections. This result casts doubt on the use of demineralised human bone matrix as a bone inductor, although it may function by other mechanisms.
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| 4. |
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| 5. |
- Aspenberg, P., et al.
(författare)
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Monkey bone matrix induces bone formation in the athymic rat, but not in adult monkeys
- 1991
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Ingår i: Journal of Orthopaedic Research. - : Wiley. - 0736-0266 .- 1554-527X. ; 9:1, s. 20-25
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Tidskriftsartikel (refereegranskat)abstract
- Demineralized bone matrix from young and adult monkeys was implanted intramuscularly for 6 weeks in athymic rats and adult monkeys. Cartilage and bone induction was evaluated by histology and calcium content. In the athymic rat, most implants induced cartilage or bone. In the monkeys, cartilage was formed only on rare occasions and there was no sign of bone formation. We conclude that (a) adult monkey bone matrix contains bone inductive properties; (b) these properties are not sufficient to induce bone formation in adult monkey muscle sites.
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| 6. |
- Aspenberg, Per, et al.
(författare)
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Teriparatide for Acceleration of Fracture Repair in Humans: A Prospective, Randomized, Double-Blind Study of 102 Postmenopausal Women With Distal Radial Fractures
- 2010
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Ingår i: JOURNAL OF BONE AND MINERAL RESEARCH. - : Wiley. - 0884-0431 .- 1523-4681. ; 25:2, s. 404-414
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Tidskriftsartikel (refereegranskat)abstract
- Animal experiments show a dramatic improvement in skeletal repair by teriparatide. We tested the hypothesis that recombinant teriparatide, at the 20 mu g dose normally used for osteoporosis treatment or higher, would accelerate fracture repair in humans. Postmenopausal women (45 to 85 years of age) who had sustained a dorsally angulated distal radial fracture in need of closed reduction but no surgery were randomly assigned to 8 weeks of once-daily injections of placebo (n = 34) or teriparatide 20 mu g (n = 34) or teriparatide 40 mu g (n = 34) within 10 days of fracture. Hypotheses were tested sequentially, beginning with the teriparaticle 40 mu g versus placebo comparison, using a gatekeeping strategy. The estimated median time from fracture to first radiographic evidence of complete cortical bridging in three of four cortices was 9.1, 7.4, and 8.8 weeks for placebo and teriparaticle 20 1 and 40 mu g, respectively (overall p = .015). There was no significant difference between the teriparaticle 40 mu g versus placebo groups (p = .523). In post hoc analyses, there was no significant difference between teriparaticle 40 1 versus 20 mu g (p = .053); however, the time to healing was shorter in teriparaticle 20 mu g than placebo (p = .006). The primary hypothesis that teriparatide 40 jug would shorten the time to cortical bridging was not supported. The shortened time to healing for teriparaticle 20 mu g compared with placebo still may suggest that fracture repair can be accelerated by teriparaticle, but this result should be interpreted with caution and warrants further study.
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| 7. |
- Khayyeri, Hanifeh, et al.
(författare)
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A Fibre-Reinforced Poroviscoelastic Model Accurately Describes the Biomechanical Behaviour of the Rat Achilles Tendon
- 2015
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 10:6
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Tidskriftsartikel (refereegranskat)abstract
- Background Computational models of Achilles tendons can help understanding how healthy tendons are affected by repetitive loading and how the different tissue constituents contribute to the tendons biomechanical response. However, available models of Achilles tendon are limited in their description of the hierarchical multi-structural composition of the tissue. This study hypothesised that a poroviscoelastic fibre-reinforced model, previously successful in capturing cartilage biomechanical behaviour, can depict the biomechanical behaviour of the rat Achilles tendon found experimentally. Materials and Methods We developed a new material model of the Achilles tendon, which considers the tendons main constituents namely: water, proteoglycan matrix and collagen fibres. A hyperelastic formulation of the proteoglycan matrix enabled computations of large deformations of the tendon, and collagen fibres were modelled as viscoelastic. Specimen-specific finite element models were created of 9 rat Achilles tendons from an animal experiment and simulations were carried out following a repetitive tensile loading protocol. The material model parameters were calibrated against data from the rats by minimising the root mean squared error (RMS) between experimental force data and model output. Results and Conclusions All specimen models were successfully fitted to experimental data with high accuracy (RMS 0.42-1.02). Additional simulations predicted more compliant and soft tendon behaviour at reduced strain-rates compared to higher strain-rates that produce a stiff and brittle tendon response. Stress-relaxation simulations exhibited strain-dependent stress-relaxation behaviour where larger strains produced slower relaxation rates compared to smaller strain levels. Our simulations showed that the collagen fibres in the Achilles tendon are the main load-bearing component during tensile loading, where the orientation of the collagen fibres plays an important role for the tendons viscoelastic response. In conclusion, this model can capture the repetitive loading and unloading behaviour of intact and healthy Achilles tendons, which is a critical first step towards understanding tendon homeostasis and function as this biomechanical response changes in diseased tendons.
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| 8. |
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| 9. |
- Kopylov, Philippe, et al.
(författare)
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Norian SRS versus functional treatment in redisplaced distal radial fractures : A randomized study in 20 patients
- 2002
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Ingår i: Journal of Hand Surgery - British and European Volume. - : SAGE Publications. - 0266-7681 .- 1532-2211. ; 27 B:6, s. 538-541
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Tidskriftsartikel (refereegranskat)abstract
- We compared the use of Norian SRS, an injectable calcium phosphate bone cement, with functional treatment of redisplaced distal radial fractures in a prospective randomized study of 20 patients. The redisplaced fractures were either rereduced and stabilized by Norian SRS, or the displaced position was accepted and was not rereduced. All wrists were immobilized in a short-arm dorsal splint for 1 week, followed by a removable splint for another 3 weeks. The chosen primary effect variable was grip strength at 7 weeks, and this did not differ between the two treatment groups. The clinical results at 6 months in both groups were similar. We conclude that aggressive treatment of redisplaced fractures of the distal radius may be unnecessary in most women aged 50 years or more.
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| 10. |
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