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| 2. |
- Kald, A, et al.
(författare)
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Reoperation as surrogate endpoint in hernia surgery. A three year follow-up of 1565 herniorrhaphies.
- 1998
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Ingår i: European Journal of Surgery. - : Oxford University Press (OUP). - 1102-4151 .- 1741-9271. ; 164:1, s. 45-50
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Analysis of reoperation and recurrence rates three years after repair of groin hernias.DESIGN: Prospective audit by questionnaire and selective follow-up.SETTING: Eight Swedish hospitals.SUBJECTS: All groin hernia operations done during 1992 on patients between the ages of 15 and 80 years.MAIN OUTCOME MEASURES: Postoperative complications, reoperation for recurrence, and recurrence.RESULTS: During 1992, 1565 hernia operations were done. The postoperative complication rate was 8% (125/1565). At 36 months postoperatively 108 recurrences had already been reoperated on, six patients with recurrences were on the waiting list for reoperation and a further 36 recurrences had been detected at follow-up. The interhospital variation in recurrence rate ranged from 3% to 20%. Postoperative complications, recurrent hernia, direct hernia and hospital catchment area over 100000 inhabitants were all factors associated with an increased relative risk of recurrence.CONCLUSIONS: The recurrence rate exceeded the reoperation rate for recurrence by almost 40% which should be taken into account if the reoperation rate is used as the endpoint after repairs of groin hernia. An audit scheme, based on prospective recording, reoperation rate, and (periodic) calculation of the recurrence rate may be used to identify risk factors for recurrence and areas in need of improvement.
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- Arnbjörnsson, E., et al.
(författare)
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Laparoscopy for nonpalpable testis in childhood : Is inguinal exploration necessary when vas and vessels are not seen?
- 1996
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Ingår i: European Journal of Pediatric Surgery. - : Georg Thieme Verlag KG. - 0939-7248 .- 1439-359X. ; 6:1, s. 7-9
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Tidskriftsartikel (refereegranskat)abstract
- A case of bilateral nonpalpable testes is described. Ultrasonography showed no testis. Laparoscopy revealed no intraabdominal testis, vas or vessels. Human chorionic gonadotrophine test suggested the presence of testicular tissue Computed tomography showed a testis present in each inguinal canal. Inguinal exploration confirmed the finding. This case stresses the importance of careful interpretation of the laparoscopic findings together with other diagnostic methods in localizing testicular tissue in patients with nonpalpable testes.
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| 6. |
- Lindhagen, Johan.E., et al.
(författare)
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Temperature changes in polymer composites during tensile loading
- 1997
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 32:15, s. 4071-4076
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Tidskriftsartikel (refereegranskat)abstract
- Temperature changes in polymeric composite laminates subjected to uniaxial monotonic tensile loading were studied. The laminates were transverse and longitudinal unidirectional glass fibre-epoxy and carbon fibre-epoxy laminates, and hybrid crossply laminates with longitudinal glass fibre-epoxy and transverse carbon fibre-epoxy layers. The temperature decreased linearly with increased tensile stress in the elastic region, except for longitudinal carbon fibre specimens (where the fibres have a small but negative coefficient of thermal expansion), which exhibited a small temperature increase. The occurrence of non-linear stress-strain behaviour in transverse carbon fibre specimens altered the rate of temperature change. When cracks appeared in laminates, the temperature immediately started to rise. The temperature changes in crossply laminates were interpreted from measurements on unidirectional specimens and knowledge of the damage mechanisms.
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| 7. |
- Lindhagen, Johan, et al.
(författare)
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Low Temperature Strength and Notch Sensitivity of Glass Mat Polypropylene
- 1997
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Ingår i: Journal of cold regions engineering. - 0887-381X .- 1943-5495. ; 11:3, s. 180-197
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Tidskriftsartikel (refereegranskat)abstract
- Literature on the effects of lowered temperature on the toughness of random short fiber composites have neither offered a clear trend nor explained the mechanisms of failure. In this work, unnotched and notched strengths at room temperature and -30°C of two glass mat polypropylenes with different fiber architectures are investigated. Observations are explained based on models for Young's modulus and notch sensitivity. Increases in strength and stiffness with lowered temperature are caused by increased matrix modulus and yield stress. Fiber bridging operating in a damage zone of substantial length was the major toughening mechanism and forms the basis for the modeling approach for notch sensitivity. Increased notch toughness at low temperature is caused by increased work of fracture in the damage zone. The increased matrix modulus and yield stress lead to an increased toughening efficiency of short fibers.
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| 8. |
- Lindhagen, Johan, et al.
(författare)
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Microscopical damage mechanisms in glass fiber reinforced polypropylene
- 1998
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Ingår i: Journal of Applied Polymer Science. - 0021-8995 .- 1097-4628. ; 69:7, s. 1319-1327
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Tidskriftsartikel (refereegranskat)abstract
- The damage mechanisms in two structurally different glass mat reinforced polypropylene materials were studied. In situ microscopy was applied during the tensile testing of thin notched sheets. Micrographs of the damage processes in the two materials are presented. The major points of damage initiation were transversely oriented fibers and fiber bundles. In the swirled mat material, cracks grew along the fiber bundles; crack formation and growth was relatively unaffected by macroscopical stress concentration. In the short fiber material, crack growth occurred at the notch. In both materials the maximum load was determined by the fibers oriented in the longitudinal direction. The different damage mechanisms were interpreted in terms of damage zone size
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| 9. |
- Lindhagen, Johan, et al.
(författare)
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Notch sensitivity and damage mechanisms of glass mat reinforced polypropylene
- 1997
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Ingår i: Polymer Composites. - : Wiley. - 0272-8397 .- 1548-0569. ; 18:1, s. 40-47
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Tidskriftsartikel (refereegranskat)abstract
- Notch Sensitivities of two structurally different glass-mat reinforced polypropylene materials (GMT) were investigated. Center hole notches in tensile specimens were used in the tests. The results show that the short fiber material has higher unnotched strength, but also higher notch sensitivity compared to a swirled mat material. Reasons for this are discussed, focusing on microstructural differences. Predictions from four different failure criteria were compared with the experimental notched strength data. The point stress and damage zone criteria were found to give the best descriptions.
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