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- Austrell, Per Erik, et al.
(författare)
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Survey of Design Methods and Material Characteristics in Rubber Engineering
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The unique properties of elastomeric materials are taken advantage of in many engineering applications. Elastomeric units are used as couplings or mountings between stiff structures. Examples of these are shock absorbers, vibration insulators, flexible joints, seals and suspensions.The development of computers and of analysis programs in this area has given engineers a new tool for the design of elastomeric components. Computer simulation by finite element analysis has become increasingly important, allowing the mechanical behavior of products with for complex geometries, as well as loading cases of different kinds to be evaluated. Computer simulations enable both static and dynamic aspects to be analyzed. These matters have been recognized by the manufacturers of rubber products and by their customers. The benefits are shorter time for product development and also quality improvements.However, the possibilities available for finding less complicated technical solutions at lower cost with the use of elastomers, has not been fully utilized. Rubber components could be employed more frequently in design if engineers were more familiar with materials of this sort.Part of the problem lies in education and in the dissemination of information. Engineers working in the design area tend to not be very familiar with elastomeric materials and their properties. The offerings of courses on the mechanics of polymers at schools and universities are very limited. Skillful engineers in this field have usually acquired their knowledge through many years of experience and not formal education.Moreover, the complicated nature of the material behavior involved makes it difficult to devise general design rules and design tools. Only recently have computers and analysis programs become powerful enough for the analysis of nonlinear elastic problems involving large strains.It is essential, if one is to become competitive in high-tech applications, to possess a thorough knowledge of computer methods, material models and test methods available.There has likewise been a lack of relevant data for the computer analysis of elastomeric materials. The design tools employed rely on the material models available and on the test data required for the calibration of these models. In many cases, the only information available for analysis is a value for the hardness of the rubber in question. The wide variety of rubber compounds is also a problem. The characterization of different materials is costly and time-consuming. There is thus a need for simple and reliable methods to characterize the different vulcanizates.
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| 3. |
- Carlsson, Annelie, et al.
(författare)
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Prevalence of IgA-antiendomysium and IgA-antigliadin autoantibodies at diagnosis of insulin-dependent diabetes mellitus in Swedish children and adolescents
- 1999
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Ingår i: Pediatrics. - : American Academy of Pediatrics (AAP). - 1098-4275 .- 0031-4005. ; 103:6 I, s. 1248-1252
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Tidskriftsartikel (refereegranskat)abstract
- Objective. This study was conducted to investigate the prevalence of celiac disease (CD) in children and adolescents at diagnosis of insulin- dependent diabetes mellitus (IDDM) before insulin treatment was started. Material and Methods. At diagnosis of IDDM, and before treatment was started, 115 children and adolescents were screened for IgA-antiendomysium (EMA) and IgA-antigliadin antibodies (AGA). Those found to be EMA-positive and/or AGA- positive were investigated further with intestinal biopsy. Results. Of the 115 patients, 2 had known CD at diagnosis of IDDM; of the remainder of patients, 6% (7/113) were found to be EMA-positive and 9% (10/113) were found to have AGA levels above normal. Of the 6 patients who underwent biopsy, 5 manifested villous atrophy. In addition, 2 patients with high EMA and AGA antibody titers refused biopsy, and 4 patients with low EMA and/or AGA titers were found to have normal titers at control before biopsy decision. Conclusion. Because the prevalence of CD at diagnosis of IDDM would seem to be 6% to 8%, screening for CD seems to be justified among patients with newly diagnosed IDDM.
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| 4. |
- Carlsson, Annelie, et al.
(författare)
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Prevalence of IgA-antigliadin antibodies and IgA-antiendomysium antibodies related to celiac disease in children with Down syndrome
- 1998
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Ingår i: Pediatrics. - : American Academy of Pediatrics (AAP). - 1098-4275 .- 0031-4005. ; 101:2, s. 5-272
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: This study was undertaken to investigate the prevalence of celiac disease in children and adolescents with Down syndrome.MATERIAL AND METHODS: Forty-three children and adolescents with Down syndrome were screened for IgA-antigliadin antibodies (AGA) and IgA-antiendomysium antibodies (EMA). Patients found to be either AGA- or EMA-positive were investigated further with intestinal biopsy.RESULTS: None of the 43 patients had known celiac disease at entry into the study; 37% (16/43) were found to have AGA levels above normal, and 16% (7/43) to be EMA-positive. Of the 15 patients who underwent biopsy, 8 manifested villous atrophy. Villous atrophy was present in all 7 of the EMA-positive patients, whereas the villi were normal in 7 of the 13 AGA-positive patients who underwent biopsy.CONCLUSIONS: EMA is a good immunologic marker for use in screening for celiac disease, and screening is justified in patients with Down syndrome.
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| 7. |
- Carlsson, Bengt, et al.
(författare)
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Generous and greedy strategies
- 1999
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Ingår i: Complexity International. - 1320-0682. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- We introduce generous, even-matched, and greedy strategies ÊÊas concepts for analyzing games. A two person prisoner's dilemma Êgame is described by the four outcomes (C,D), (C,C), (D,C), and (D,D). In a generous strategy the proportion of (C,D) is larger than that of (D,C), i.e. the probability of facing a defecting agent is larger than the probability of defecting. An even-matched strategy has the (C,D) proportion approximately equal to that of (D,C). A greedy strategy is an inverted generous strategy. The basis of the partition is that it is a zero-sum game given that the sum of the proportions of strategies (C,D) must equal that of (D,C). In a population simulation, we compare the prisoner's dilemma (PD) game with the chicken game Ê(CG), given complete as well as partial knowledge of the rules for moves in the other strategies. In a traffic intersection example, we expected a co-operating generous strategy to be successful when the cost for collision was high in addition to the presence of uncertainty. The simulation indeed showed that a generous strategy was successful in the CG part, in which agents faced uncertainty about the outcome. If the resulting zero-sum game is changed from a PD game to a CG, or if the noise level is increased, it will favor generous strategies rather than an even-matched or greedy strategies.
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| 9. |
- Carlsson, Bengt Å., et al.
(författare)
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Alpine and subalpine vegetation
- 1999
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Ingår i: Swedish plant geography. - Uppsala : Svenska växtgeografiska sällskapet. - 9172100842 ; , s. 75-89
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Bokkapitel (refereegranskat)
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| 10. |
- Carlsson, Christina, 1968, et al.
(författare)
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Dancing DNA in Capillary Solution Electrophoresis
- 1995
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 117:13, s. 3871-3872
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Tidskriftsartikel (refereegranskat)
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