| 1. |
- Edelson, R. A., et al.
(författare)
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Multiwavelength observations of short-timescale variability in NGC 4151. IV. Analysis of multiwavelength continuum variability
- 1996
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 470:1, s. 364-377377
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Tidskriftsartikel (refereegranskat)abstract
- For pt.III see ibid., vol.470, no.1, p.349-63 (1996). Combines data from the three preceding papers in order to analyze the multi wave-band variability and spectral energy distribution of the Seyfert 1 galaxy NGC 4151 during the 1993 December monitoring campaign. The source, which was near its peak historical brightness, showed strong, correlated variability at X-ray, ultraviolet, and optical wavelengths. The strongest variations were seen in medium-energy (~1.5 keV) X-rays, with a normalized variability amplitude (NVA) of 24%. Weaker (NVA=6%) variations (uncorrelated with those at lower energies) were seen at soft gamma-ray energies of ~100 keV. No significant variability was seen in softer (0.1-1 keV) X-ray bands. In the ultraviolet/optical regime, the NVA decreased from 9% to 1% as the wavelength increased from 1275 to 6900 Aring. These data do not probe extreme ultraviolet (1200 Aring to 0.1 keV) or hard X-ray (250 keV) variability. The phase differences between variations in different bands were consistent with zero lag, with upper limits of lsim0.15 day between 1275 Aring and the other ultraviolet bands, lsim0.3 day between 1275 Aring and 1.5 keV, and lsim1 day between 1275 and 5125 Aring. These tight limits represent more than an order of magnitude improvement over those determined in previous multi-wave-band AGN monitoring campaigns. The ultraviolet fluctuation power spectra showed no evidence for periodicity, but were instead well fitted with a very steep, red power law (ales-2.5)
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| 2. |
- Crenshaw, D. M., et al.
(författare)
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Multiwavelength observations of short-timescale variability in NGC 4151. I. Ultraviolet observations
- 1996
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 470:1, s. 322-335335
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Tidskriftsartikel (refereegranskat)abstract
- Presents the results of an intensive ultraviolet monitoring campaign on the Seyfert 1 galaxy NGC 4151, as part of an effort to study its short-timescale variability over a broad range in wavelength. The nucleus of NGC 4151 was observed continuously with the International Ultraviolet Explorer for 9.3 days, yielding a pair of LWP and SWP spectra every ~70 minutes, and during 4 hr periods for 4 days prior to and 5 days after the continuous-monitoring period. The sampling frequency of the observations is an order of magnitude higher than that of any previous UV monitoring campaign on a Seyfert galaxy. The continuum fluxes in bands from 1275 to 2688 Aring went through four significant and well-defined ldquoeventsrdquo of duration 2-3 days during the continuous-monitoring period. The authors find that the amplitudes of the continuum variations decrease with increasing wavelength, which extends a general trend for this and other Seyfert galaxies to smaller timescales (i.e., a few days). The continuum variations in all the UV bands are simultaneous to within an accuracy of ~0.15 days, providing a strict constraint on continuum models. The emission-line light curves show only one major event during the continuous monitoring (a slow rise followed by a shallow dip) and do not correlate well with continuum light curves over the short duration of the campaign, because the timescale for continuum variations is apparently smaller than the response times of the emission lines
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| 3. |
- Bengtsson, Peter, et al.
(författare)
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Computer-Aided Planning of Production, Working and Residential Environments
- 1996
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Ingår i: International Journal of Industrial Ergonomics. - : Elsevier BV. - 0169-8141 .- 1872-8219. ; 17:1, s. 59-68
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses a computer-aided planning methodology and its applicability for planning of industrial production and working environments as well as for planning of residential and working environments for the differently abled. The methodology has been developed and evaluated in six case studies in mechanical industries and in six case studies related to adaptations for the differently abled. The results from the case studies indicate that computer-supported modelling and visualisation may serve as a common and efficient language facilitating communication about multifaceted environmental planning issues. The methodology is a cost-effective way of demonstrating layout ideas and testing dynamic activities like manufacturing and transportation. Corporate groups comprising people involved in, or affected by, development work seem to be a fruitful approach for cooperation, one which enhances learning and creativity. Such groups may be a proper forum for the dissemination of information, exchange of opinions, utilisation of both expert and lay experiences, and for public testing of current reality or future plans in such a way that mutual understanding between different professional categories is increased, hence promoting internal commitment.
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| 4. |
- Akselsson, Roland, et al.
(författare)
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Multidisciplinary Research on Integration of Human Factors and Production Concepts such as TQM - A Participatory Discussion Session
- 1999
-
Ingår i: Proceedings of the Conference on TQM and Human Factors. - 9172195207 ; 2, s. 439-448
-
Konferensbidrag (refereegranskat)abstract
- A discussion session where the conference participants are invited to participate is planned. One topic for the session is to discuss experiences of multidisciplinary research on integration of human factors and different production concepts applied in change processes within Swedish companies. An important question that the discussion will focus on is: How to get high quality in multidisciplinary research? Another topic is to discuss how people from different disciplines in the companies interact with each other and with the researchers. Researchers from the centre Change@Work at Lund University in Sweden will present some of their experiences from several years of multidisciplinary research in companies. As a background the research questions within Change@Work are presented below. Discussions during the workshop will be performed according to methods used by the researchers in their research in the companies. All discussion will be documented and later sent to all workshop participants.
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| 5. |
- Bengtsson, Peter, et al.
(författare)
-
Cooperation in Planning of Production and Working Environments Supported by Computer Graphics
- 1996
-
Ingår i: The International Journal of Human Factors in Manufacturing. - 1045-2699. ; 6:2, s. 101-130
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Tidskriftsartikel (refereegranskat)abstract
- A methodology for studying change processes in working life combining computer-aided planning and cooperation in project groups is evaluated. The methodology is applied and studied in a planning workshop with representatives from manufacturing industries—managers, production engineers, supervisors as well as shop floor workers—and from health-and-safety agencies utilizing the methodology for planning of production, layout, and working environment. The results are presented and discussed with respect to cooperation in project groups, outline of proposals, topics of discussion, and pictures as planning tools.
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| 6. |
- Bengtsson, Peter, et al.
(författare)
-
Planning Working Environment and Production by Using Paper Drawings and Computer Animation
- 1997
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Ingår i: Ergonomics. - : Informa UK Limited. - 0014-0139 .- 1366-5847. ; 40:3, s. 334-347
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Tidskriftsartikel (refereegranskat)abstract
- It is assumed that pictorial visualization can be used to facilitate communication between industrial professionals when planning working environments and production. This article analyses how managers, supervisors, machine operators, and occupational health and safety officials, accustomed to using both paper drawings and computer animation of both shop floor and workplace view, evaluate these four types of visualization in relation to a set of planning issues. Twenty-four subjects participated in a controlled two-day planning workshop. They designed a new production layout by means of computer graphics, and responded to a questionnaire. From the analysis it may be concluded that the four types of visualization are unique enough to be evaluated differently with regard to some of the planning issues. Hence, great care should be devoted to analysing what features a visualization of a production layout or a working environment aims at illustrating. Furthermore, it can be concluded that each of the four types of visualization seems to be significant for planning activities in ways that can be anticipated. Shop floor view and workplace view is valuable for planning issues related to survey of a plant and specific machines, respectively. Computer animation is in general preferable to a paper drawing concerning dynamic planning issues. Computer animation of workplace view is valuable for planning issues related to working environment considerations. All of the four types of visualization are less significant for illustrating or describing physical factors of the working environment.
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| 7. |
- Hansson, Lars, et al.
(författare)
-
Annie, a Tool for Integrating Ergonomics in the Design of Car Interiors
- 1999
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An example of a result from a long-term cooperation with Lund University (together with professor Roland Axelsson at the Department for Work Environment) there some of the authors. (Engström) gained extensive grants (Wallenberg Stifelsen regarding equipment as well as other founding from e.g. the Swedish Work Environment Found).
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| 8. |
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| 9. |
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| 10. |
- KAWASHIMA, R, et al.
(författare)
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Positron-emission tomography studies of cross-modality inhibition in selective attentional tasks: closing the "mind's eye"
- 1995
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 92:13, s. 5969-5972
-
Tidskriftsartikel (refereegranskat)abstract
- It is a familiar experience that we tend to close our eyes or divert our gaze when concentrating attention on cognitively demanding tasks. We report on the brain activity correlates of directing attention away from potentially competing visual processing and toward processing in another sensory modality. Results are reported from a series of positron-emission tomography studies of the human brain engaged in somatosensory tasks, in both "eyes open" and "eyes closed" conditions. During these tasks, there was a significant decrease in the regional cerebral blood flow in the visual cortex, which occurred irrespective of whether subjects had to close their eyes or were instructed to keep their eyes open. These task-related deactivations of the association areas belonging to the nonrelevant sensory modality were interpreted as being due to decreased metabolic activity. Previous research has clearly demonstrated selective activation of cortical regions involved in attention-demanding modality-specific tasks; however, the other side of this story appears to be one of selective deactivation of unattended areas.
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