1. |
- Clavel, J., et al.
(författare)
-
Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. I. An 8 month campaign of monitoring NGC 5548 with IUE
- 1991
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 366:1, s. 64-8181
-
Tidskriftsartikel (refereegranskat)abstract
- The authors present emission-line and ultraviolet continuum observations of a type I Seyfert galaxy in which the time resolution is adequate for describing the character of variability. Using the IUE satellite, the nucleus of NGC 5548 was observed every 4 days for a period of 8 months. Its mean properties-continuum shape, line ratios-are not unusual for type I Seyfert galaxies, but it was found to be strongly variable. The ultraviolet continuum flux and broad emission line fluxes varied significantly, going through three large maxima and three deep minima. The great majority of all variations were well resolved in time. The data lend qualitative support to the view that photoionization by the nuclear continuum is responsible for driving the emission lines
|
|
2. |
- Garwicz, Martin, et al.
(författare)
-
Spread of synaptic activity along parallel fibres in cat cerebellar anterior lobe
- 1992
-
Ingår i: Experimental Brain Research. - 0014-4819. ; 88:3, s. 615-622
-
Tidskriftsartikel (refereegranskat)abstract
- 1. Mossy fibre evoked activity in the cerebellar cortex elicited by peripheral electrical stimulation was studied in chloralose anesthetized cats. The distribution of intracortical field potentials in the C3 and D zones was mapped in order to determine if there is a spread of synaptic activity outside the mossy fibre termination area. This area was identified by the presence of short latency synaptic field potentials in the granular layer. 2. Molecular layer field potentials were recorded up to 1.5 mm outside the mossy fibre termination area. The latencies of these potentials increased with increasing distance from the mossy fibre termination area, corresponding to a conduction velocity of about 0.4 m/s. 3. Recordings from Purkinje cells, within and outside the mossy fibre termination area, revealed an increase of simple spike activity at latencies corresponding to those of the field potentials in the same location. 4. From the spatial and temporal characteristics of the evoked activity, it is concluded that a mossy fibre input results in spread of synaptic activity along the parallel fibres. 5. The findings are discussed in relation to the recently discovered microzonal organization of the C3 zone. It is proposed that the organization of this zone offers a possibility for the control of muscle synergies, each synergy being represented by a mossy fibre input and the specific set of microzones activated by this input via the parallel fibres.
|
|
3. |
- Jeppson, Kjell, 1947, et al.
(författare)
-
Single Event Upset Behavior of CMOS Static RAM Cells
- 1993
-
Ingår i: JPL Technical Report Server. ; 1993
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- An improved state-space analysis of the CMOS static RAM cell is presented. Introducing the concept of the dividing line, the critical charge for heavy-ion-induced upset of memory cells can be calculated considering symmetrical as well as asymmetrical capacitive loads. From the critical charge, the upset-rate per bit-day for static RAMs can be estimated.
|
|
4. |
- Jern, Sverker, 1954, et al.
(författare)
-
Short-term reproducibility of a mental arithmetic stress test.
- 1991
-
Ingår i: Clinical science (London, England : 1979). - 0143-5221. ; 81:5, s. 593-601
-
Tidskriftsartikel (refereegranskat)abstract
- 1. To evaluate the short-term reproducibility of heart rate, oscillometrically determined blood pressure, antecubital venous plasma catecholamine concentrations and subjective responses to strictly standardized mental arithmetic, we performed two identical tests 1 h apart in 14 young, healthy and normotensive male subjects (age 22-35 years). 2. Heart rate and blood pressure responses to the two stress tests were highly correlated, when expressed both as correlations between levels attained during stress (rs greater than 0.80 throughout) and as absolute reactivity measures (all rs greater than 0.75). Also, subjective stress responses were highly correlated, when considering both levels during stress and reactivity (r = 0.97 and r = 0.85, respectively). Stress levels of catecholamines were correlated, but the change scores (reactivity) were unrelated. 3. The measurement error SD for heart rate was 2.6 and 3.0 beats/min for reactivity and stress levels, respectively. The corresponding SD for blood pressure ranged between 2.7 and 4.4 mmHg. Subjective stress experience showed an SD of a similar magnitude. The responses of plasma catecholamine concentrations were subject to considerable variability. 4. It is concluded that haemodynamic and subjective stress responses and stress levels during the mental arithmetic stress test show acceptable reproducibility and high test-retest correlations. However, stress-induced changes in venous plasma catecholamine concentrations show low reproducibility.
|
|