| 1. |
- Lindberg, Lars, et al.
(författare)
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Nitric oxide gives maximal response after coronary artery bypass surgery
- 1994
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Ingår i: Journal of Cardiothoracic and Vascular Anesthesia. - : Elsevier BV. - 1532-8422 .- 1053-0770. ; 8:2, s. 182-187
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Tidskriftsartikel (refereegranskat)abstract
- The dose-response to inhalation of nitric oxide (NO) after coronary artery bypass surgery was studied in seven patients with normal preoperative lung function and chest radiograms. During postoperative controlled ventilation with PEEP 5 and 10 cmH2O, the patients inhaled NO in concentrations of 2 to 25 ppm, in random order, for 6 to 10 minutes. Hemodynamic and oximetric data were analyzed before, 5 minutes after start of the NO inhalation, and 5 minutes after the cessation. The response was the same at all concentrations; mean pulmonary artery pressure decreased by 11 +/- 1% (P < 0.05) and pulmonary vascular resistance decreased by 22 +/- 2% (P < 0.05). Systemic hemodynamics did not change, but oximetric parameters tended to improve. Changes in PEEP did not affect the response. It is concluded that, in patients who have undergone coronary artery bypass grafting, inhalation of 2 to 25 ppm NO causes a dose-independent decrease in pulmonary artery pressure and pulmonary vascular resistance. In order to investigate the dose-response curve, concentrations lower than 2 ppm of NO must be used.
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| 4. |
- Andersson, Agneta, et al.
(författare)
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Domiciliary liquid oxygen versus concentrator treatment in chronic hypoxaemia: a cost-utility analysis
- 1998
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Ingår i: European Respiratory Journal. - 1399-3003. ; 12:6, s. 1284-1289
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Tidskriftsartikel (refereegranskat)abstract
- Whether long-term oxygen therapy (LTOT) improves quality of life in chronic hypoxaemia has been questioned. LTOT with an oxygen concentrator (C/C) and gas cylinders for ambulation is considered cumbersome compared to mobile liquid oxygen equipment (L). The hypothesis for this study was that LTOT with liquid oxygen treatment (L) improves patients' health-related quality of life, but that it is also more expensive compared to concentrator (C/C) treatment. A prospective, randomized multicentre trial comparing C/C with L for LTOT was conducted during a six-month period. Fifty-one patients (29 on L and 22 on C/C) with chronic hypoxaemia, regularly active outside the home, participated in the study initially. Costs for oxygen were obtained from the pharmacies. Patient diaries and telephone contacts with members of the healthcare sector were used to estimate costs. Health-related quality of life was measured by the Sickness Impact Profile (SIP) and the EuroQol, instruments at the start and after 6 months. The average total cost per patient for group C/C for the six-month period was US$1,310, and for group L it was US$4,950. Health-related quality of life measured by the SIP instrument showed significant differences in favour of group L in the categories/dimensions of physical function, body care, ambulation, social interaction and total SIP score. In conclusion, liquid-oxygen treatment was more expensive compared to concentrator treatment. However, treatment effects showed that liquid oxygen had a better impact on quality of life.
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| 5. |
- Bai, Guohua, et al.
(författare)
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A sociocybernetic approach to information systems development
- 1999
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Ingår i: Kybernetes. - : Emerald. - 0368-492X .- 1758-7883. ; 28:6-7, s. 792-809
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Tidskriftsartikel (refereegranskat)abstract
- A principal problem of information systems (IS) development today is how to integrate the work activity and social context of users into the IS which is being designed. This paper aims to delineate a sociocybernetic approach which enlightens the relationship between IS design activity, use activity, and the embedded social context. First and second order cybernetics are employed as a general skeleton or structure for conducting the sociocybernetic approach. Approaches from social autopoiesis theory and activity theory are introduced respectively, to provide the skeleton of cybernetics with flesh and blood elements of real problems. An emerging conceptual body resulting from an organic integration of the cybernetic structure and social-psychological elements which demonstrates the relationship between IS design activity, use activity, and embedded social context is presented.
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| 6. |
- Bai, Guohua, et al.
(författare)
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Dialectical approach to systems development
- 1998
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Ingår i: Systems research and behavioral science. - 1092-7026 .- 1099-1743. ; 15:1, s. 47-54
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Tidskriftsartikel (refereegranskat)abstract
- This paper will approach the nature of system development based on dialectical thinking. To conduct this approach, the paper is divided into three parts. In the first part, the concept 'contradiction' is introduced in the context of dialectical thinking. In the second part,'systems development' is discussed in terms of contradiction in the Activity Theory. And in the last part,'information systems development' is presented as an example to demonstrate how information systems are developed in the light of this dialectical approach.
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| 7. |
- Bai, Guohua, et al.
(författare)
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Sociocybernetics : activity and communication in modern society
- 1998
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Konferensbidrag (refereegranskat)abstract
- Integrates cybernetics & sociology as a coherent framework -- sociocybernetics -- introducing fundamental basics of the traditional, or so-called first-order, cybernetics. Problems & limitations in applying first-order cybernetics in sociological studies are approached from methodological & ontological perspectives. Presented is an organic integration of cybernetics (Wiener, N., 1948; Geyer, F., 1995), activity theory (Engestrom, Y., 1987; Leont'ev, A. N., 1981), autopoietic sociological theory (Luhmann, N., 1986 [see abstract 86c00792]), systems approach (Churchman, C. W., 1979), & communication theory (Wiener, N., 1955) into a coherent sociocybernetic framework
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| 8. |
- Beckman, William A, et al.
(författare)
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TRNSYS, the most complete solar energy system modeling and simulation software
- 1994
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Ingår i: Renewable energy. - 0960-1481 .- 1879-0682. ; 5:1-4, s. 486-488
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Tidskriftsartikel (refereegranskat)abstract
- The five computer programs TRNSYS, PRESIM, TRNSED, ONLINE, and PREBID have been put together into a program package which is the most complete solar energy system modeling and simulation software that is available today.
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| 10. |
- Broman, Lars, et al.
(författare)
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Enhancing the optical efficiency of a thermophotovoltaic generator using square cones in combination with interference filters
- 1998
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Ingår i: Second World Conference on Photovoltaic Solar Energy Conversion. - Wien, Österrike.
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Konferensbidrag (refereegranskat)abstract
- The optical efficiency is a week link in all TPV systems. Many different approaches have been studied earlier, but not much on the possibility to use interference filters. Such filters can be designed to get alsmost any desired optical performance, as long as it is allowed to use a large number of layers in the multilayer stack. In practical applications this is very often not acceptable. Nevertheless such filters can still be quite good, at least for a very narrow range of incident angles. Therefore a double-cone geometry is proposed to be used in combination with such filters. This geometry will limit the range of incident angles onto the filter, which will then act more efficiently. The influence of the geometry is evaluated by means of model experiments, and a computer program has been constructed to be able to simulate this type of geometry using ray-tracing technique.
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