| 1051. |
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| 1052. |
- Ross, Russell G.
(författare)
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Predicting the equation of state of condensed materials through use of low-pressure expansion and room-temperature compression data
- 1992
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Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 53:7, s. 857-864
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Tidskriftsartikel (refereegranskat)abstract
- Empirical prediction of the equation of state (EOS) over an area in pressure-temperature (p-T) space was attempted using primary data for low-pressure (p0) expansion and room-temperature (T0) compression together with various ansatz to effectively restrict the functional form which the EOS could have. Tests against experimental data for the EOS of a variety of substances at p-T co-ordinates which were not on the p0 isobar or T0 isotherm showed that some ansatz could successfully predict the EOS at a general p-T co-ordinate which was within the ranges of the primary data. However, success rate in prediction was only at about the 50% level and furthermore no systematics were detected which would enable prior selection of the appropriate ansatz to be applied to a specific substance. Theoretical models for the EOS which include a general assumption of one of the ansatz under consideration were therefore shown to be lacking in empirical justification. It was concluded that at present reliable knowledge of the EOS over an area in p-T space can only be obtained through direct experimental determination.
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| 1053. |
- Ross, Russell G.
(författare)
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Thermal conductivity and disorder in nonmetallic materials
- 1991
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Ingår i: Physics and chemistry of liquids (Print). - : Taylor & Francis. - 0031-9104 .- 1029-0451. ; 23:4, s. 189-210
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Tidskriftsartikel (refereegranskat)abstract
- Experimental results for thermal conductivity λ are presented and discussed for a range of nonmetallic materials. Disorder, involving both static and dynamic aspects, is covered over a range from well-ordered solids to glasses. Amongst intermediately-disordered (ID) solids which are considered the cases of plastic crystal phases, the glassy crystal state, inclusion compounds and chiral substances receive detailed attention. Emphasis is given to relatively-high temperature (T) where results for λ of glasses and ID solids are shown to be similar. It is demonstrated how data for λ(T) which have been measured under isobaric conditions can be transformed to isochoric conditions, and this transformation is shown to be important for purposes of analysis of results. Limitations at high temperature of the phonon picture of heat transport are explored using an empirical approach and an alternative picture involving hopping of localized vibrational excitations is also briefly discussed.
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| 1054. |
- Ross, Russell G.
(författare)
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Thermal conductivity of the urea-hexadecane inclusion compound
- 1990
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Ingår i: Journal of inclusion phenomena and molecular recognition in chemistry. - : Kluwer Academic Publishers. - 0923-0750 .- 2212-1765 .- 1573-1111. ; 8:1-2, s. 227-233
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity λ and the heat capacity per unit volume ϱcp have been measured for the urea-hexadecane inclusion compound using the transient hot-wire method. Measurements were made under isobaric conditions at a pressure of 0.1 GPa and in the temperature range of 100–300 K. There was evidence for a phase transition at a temperature of about 160 K, in reasonable agreement with previous work. For the high-temperature phase λ was independent of temperature within ±1%. The low-temperature phase showed a weak temperature dependence, with (d lnλ/d lnT)p = −0.13. It was inferred that interaction between acoustic phonons and low-frequency vibrational excitations of the guest molecules made a major contribution to the thermal resistivity. For the quantity ϱcp a weak maximum was observed in the region of the phase transition temperature.
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| 1055. |
- Rosser, J. Barkley, et al.
(författare)
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Discontinuous change in multilevel hierarchical systems
- 1994
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Ingår i: Systems Research and Behavioral Science (Systems Research). - : John Wiley & Sons Ltd. - 1092-7026. - 9781840649895 ; 11:3, s. 77-93
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Tidskriftsartikel (refereegranskat)abstract
- We examine sources and dynamics of discontinuous changes in discrete multi-level hierarchical ecological-economic systems. We hypothesize the anagenetic moment, the creation of a new level of hierarchy, as arising from variable entrainment at some level. Bottom-up as well as top-down dynamics are studied and competing theories of the sources of such discontinuities are reviewed. Implications for the analysis of complex ecological-economic systems are considered depending on whether they are characterized by single hierarchy, bi-hierarchy, or matrix hierarchy relationships.
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| 1056. |
- Rudberg, S, et al.
(författare)
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Indications that branched chain amino acids, in addition to glucagon, affect the glomerular filtration rate after a high protein diet in insulin-dependent diabetes
- 1991
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Ingår i: Diabetes research. - Edinburgh, Scotland : Teviot-Kimpton Publications. - 0265-5985. ; 16:3, s. 101-109
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Tidskriftsartikel (refereegranskat)abstract
- Hormonal changes and whole blood free amino acid levels and their relation to renal function were measured in 12 insulin-dependent diabetic patients after two 10-day periods with a diet consisting of 10% and 20% respectively of the energy as protein. The patients were 15-21 years old and mean duration of diabetes was 12 (5-20) years. Glomerular filtration rate, renal plasma flow, and albumin excretion rate were measured together with plasma concentrations of glucagon, growth hormone, insulin-like growth factor 1 (IGF-1), somatostatin, serum insulin and free amino acids in blood. Glomerular filtration rate was 123 +/- 3 ml/min/1.73 m2 on high protein diet and 113 +/- 3 ml/min/1.73 m2 on low protein diet (p = 0.02). Renal plasma flow was unchanged. Glucagon, IGF-1, branch chained amino acids (BCAA), tyrosine, phenylalanine, lysine, and methionine were increased after the high protein diet. Growth hormone, somatostatin, insulin, and other amino acids remained unchanged. The increase in glomerular filtration rate was significantly correlated to the increase in glucagon, isoleucine, and valine (glucagon r = 0.71, p = 0.01, isoleucine r = 0.59, p = 0.04, valine r = 0.62, p = 0.03). In a multiple regression model the increase in glomerular filtration correlated most strongly to the increase in isoleucine, followed by valine and glucagon. Together these variables explained 88% of the total variance of the change in glomerular filtration rate (r2 = 0.88, p = 0.001). Albumin excretion rate was correlated to IGF-1 (r = 0.86, p < 0.001) on the high protein diet. The regulation of GFR seems to depend on a combined effect of BCCA and glucagon, whereas microalbuminuria seems to be related to IGF-1.
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| 1057. |
- Rundgren, M, et al.
(författare)
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Intracerebroventricular infusion of glycine stimulates vasopressin release in conscious sheep.
- 1993
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Ingår i: NeuroReport. - 0959-4965 .- 1473-558X. ; 4:8, s. 1052-4
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Tidskriftsartikel (refereegranskat)abstract
- We have previously observed that elevation of the plasma glycine concentration stimulates vasopressin (AVP) release in man and sheep. In the present study we show that this effect of glycine can be elicited directly via a cerebral site of action in conscious sheep. Intracerebroventricular infusions of 0.05 and 0.15 M glycine solutions increased the plasma AVP concentration by 6 and 50 times, respectively, while no effect on water intake was observed. Hyperhydration did not block the stimulation of AVP release. No behavioural side effects, or changes in blood pressure, were observed in response to the infusions.
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| 1058. |
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| 1059. |
- Rönnerman, Karin, 1952-
(författare)
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Lärarinnor utvecklar sin praktik : en studie av åtta utvecklingsarbeten på lågstadiet
- 1993
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this study is to contribute to the understanding of development projects carried out by teachers within the Swedish 9-year compulsory school. The study concentrates on the everyday classroom work of the teachers, firstly when there were extra funds to use for the development projects, and secondly, when the funding had expired. Eight projects at the primary level were selected. Each project was visited three times during the first year. A follow up was made three years later. Data were collected by way of interviews, questionnaires and observations.The projects had different aims, contents and organization. Some projects changed or developed their aims and contents in the course of the project period, while others kept their original direction. Differences in the development of project activities were found to be related to such factors as the amount of personal support given by headmasters and colleagues, and on whose initiative a project was started, whether by the authorities or by the teachers themselves. Within the framework of the projects, the teachers often instigated relevant in-service training, developed new forms of cooperation, sought to integrate school subjects and tried new pedagogic practices. When financial support was terminated, the new ideas and the new practices were incorporated in the changed every day way of working.The project work tended to make the teachers feel more harmonious and whole, in that the activities tended to tie the teacher's personality and career more firmly together. Besides this personal development, the teachers felt that the project work enhanced more and closer cooperation in the schools. The teachers emphasized that it had become very important for them to collaborate, and that they felt they were no longer left alone with the responsibilities and problems in the classroom. The projects led to more committed pedagogical discussions in the staff- rooms resulting in a claim for more knowledge. The project teachers often invited lecturers and arranged other forms of in-service training.The results of the study are discussed in relation to theories of school development, teacher work and career as well as to gender theories.
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| 1060. |
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