| 1. |
- Cedergren, Magnus, et al.
(författare)
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Crystallization temperature of amorphous Fe80B20 under pressure
- 1978
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier. - 0022-3093 .- 1873-4812. ; 30:1, s. 69-76
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Tidskriftsartikel (refereegranskat)abstract
- The resistance of rapidly quenched Fe80B20 was recorded versus T at a rate of 7 K/min and various pressures up to 2.5 GPa. The onset of crystallization, Tx, was defined by extrapolation at the sharp change in resistance associated with crystal growth. The resulting slope of Tx is 15 K/GPa. Separate measurements at atmospheric pressure yielded Tx versus rate of temperature increase, R = dT/dt. Crystallization times from the literature were recalculated to yield Tx, and the results are compared with our data. Nominally amorphous materials of the same composition show markedly different properties. It is also shown that the variation of Tx with R is mostly due to the change in viscosity.
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| 2. |
- Kjellberg, Anders, et al.
(författare)
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Physiological response patterns during 'intake' and 'rejection' tasks
- 1979
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Ingår i: Biological Psychology. - Netherlands : Elsevier. - 0301-0511 .- 1873-6246. ; 9:1, s. 63-76
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Tidskriftsartikel (refereegranskat)abstract
- Two 2-min tasks, one requiring outer-directed attention (intake task), the other a mental arithmetic task (rejection task) were presented to 20 subjects. According to Lacey the distinguishing feature of the response to intake task are cardiac deceleration and blood pressure decreases. None of these responses was obtained. Some variables, however, were only affected by one of the task; the intake task led to a decreased hand (skin) blood flow and an increased hand vascular resistance, whereas a heart rate acceleration and increased forearm (muscle) blood flow and decreased forearm vascular resistance were observed during the rejection task. Blood pressure, respiration rate and skin conductance were similarly affected by the two tasks. Inconsistencies among previous studies of the response to the two types of tasks were discussed and found to be partially explained by methodological differences.
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| 3. |
- Magnusson, Eva, 1947-
(författare)
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The effects of controlled muscle tension on performance and learning of heart-rate control
- 1976
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Ingår i: Biological Psychology. - Netherlands : Elsevier. - 0301-0511 .- 1873-6246. ; 4:2, s. 81-92
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Tidskriftsartikel (refereegranskat)abstract
- Thirty female subjects were divided in three groups and instructed in group I to increase their HRs with the aid of continuous feedback of performance, while they tensed their right forearm muscles 20% of maximal voluntary contraction. In the last session only feedback was used. Group II were trained with feedback only. Group III for the first two sessions tensed their muscles only, and in the last session trained HR increases with feedback only.Group I was superior in HR performance in the first two sessions. In the third session they deteriorated significantly and could not be distinguished from the other two groups. The results were interpreted in terms of relations between somatic and autonomic events and transfer between different states of somatic involvement during learning.Electrodermal activity and respiration were included as control variables.
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| 4. |
- Malmhäll, Roger, et al.
(författare)
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Hall resistivity of a magnetic amorphous alloy : Effects of thermal cycling and annealing
- 1978
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier. - 0022-3093 .- 1873-4812. ; 28:2, s. 159-176
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the effects of thermal cycling and annealing on the Hall resistivity ρH and electrical resistivity ρ of an amorphous magnetic material, Metglas 2826A. Thermal cycling up to 600 K has no significant effect on ρ but changes ρH, especially at T > 300 K. Annealing at higher temperatures Ta affects ρH more strongly than it influences ρ. For Ta = 650 K the Curie temperature jumps by ∼ 300 K and this, combined with X-ray data, is regarded as being symptomatic of the onset of crystallization. It is demonstrated that, for a fixed T, the variation of the extraordinary Hall coefficient R1 is simple correlated with that of ρ for both the amorphous material and the annealed (crystallized) specimens. Furthermore, for a given Ta, the variations of R1 and ρ as functions of temperature exhibit the same formal relationship. The temperature dependence of ρ in the annealed specimens is rendered plausible in terms of recent theories of disordered materials. Room-temperature studies of electron spin resonance and the field dependence of the magnetization are also reported.
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| 5. |
- Nordhage, Frank, et al.
(författare)
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Injection charging of polymeric capacitors
- 1976
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Ingår i: Journal of Electrostatics. - : Elsevier. - 0304-3886 .- 1873-5738. ; 2:4, s. 317-326
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Tidskriftsartikel (refereegranskat)abstract
- The charging of non-polar polymer capacitors due to a step voltage is studied as a function of time. Apart from the classical charging, which is completed in nanoseconds, it is found that the current flowing into the capacitor can be described as a sum of two exponential functions of time, the time constants differing by a factor of ten. In the case of polyethylene, at least, it is clear that the shorter time constant is connected with carrier injection into the polymer from the metal surface. The longer time constant is presumable due to carrier migration within the volume of the dielectric. These findings may be correlated with our previous results on the field dependence of electrostatic charging and support the model of carrier injection to a finite depth.
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| 6. |
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| 7. |
- Nordhage, Frank, et al.
(författare)
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Sliding and rolling electrification of a NaCl-metal system
- 1977
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Ingår i: Journal of Electrostatics. - : Elsevier. - 0304-3886 .- 1873-5738. ; 3:4, s. 371-383
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Tidskriftsartikel (refereegranskat)abstract
- The electrification of (100)-oriented NaCl surfaces has been studied as a function of sliding velocity and normal force between an Au electrode and the insulator surface. In addition various crystallographic orientations of NaCl surfaces have been investigated with electrodes of different metals. A series of experiments comparing the sliding and rolling modes of separation has also been carried out on (100) surfaces. The results suggest that electrons are transferred from or into trapping levels in the forbidden energy range of the NaCl crystal.
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