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- Johansson, Roger, et al.
(author)
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Eye movements play an active role when visuospatial information is recalled from memory
- 2012
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In: Journal of Vision. ; 12:9
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Conference paper (peer-reviewed)abstract
- Abstract in Undetermined Whilst it has been established that spontaneous eye movements occur with visual imagery and that they are comparable with those from an original scene inspection (e.g., Brandt & Stark, 1997; Johansson, Holsanova, & Holmqvist, 2006), the exact purpose of these eye movements has been a hot topic of debate (cf., Ferreira et al., 2008; Richardson et al., 2009). Do they have an active and functional role in memory retrieval or are they merely an epiphenomenon? In a recent study we reported that when eye movements were prohibited for participants who orally described pictures from memory, their recollections became altered and impaired (Johansson, Holsanova, Dewhurst, & Holmqvist, (in press). Journal of Experimental Psychology: Human Perception and Performance). The current study was designed as a follow-up, aiming to uncover exactly how imposing different eye movements on participants affects memory retrieval processes. Eye movements were recorded from participants who recalled properties and spatial arrangements of sets of objects under four different manipulations: (1) free viewing on a blank screen; (2) gazing at a fixation cross; (3) looking at an area which was matched with the original locations of the objects to be recalled; (4) looking at an area which did not match the original locations of the objects to be recalled. By restricting eye movements in different ways during recall, we demonstrate the sensitivity of retrieval performance to specific eye movement manipulations. Results provide evidence that eye movements do have an active and supportive role when visuospatial information is recalled by highlighting the circumstances under which a visual memory is hampered. Additionally, findings suggest that the influence of "eye movements to nothing" is primarily related to the processing and retrieval of spatial information.
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- Andersson, Kenneth, 1970-, et al.
(author)
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Backward-forward motion compensated prediction
- 2002
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In: Proceedings of ACIVS 2002 (Advanced Concepts for Intelligent Vision Systems), Ghent, Belgium, September 9-11, 2002. ; , s. 260-267
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Conference paper (peer-reviewed)abstract
- This paper presents new methods for use of dense motion fields for motion compensation of interlaced video. The motion is estimated using previously decoded field-images. An initial motion compensated prediction is produced using the assumption that the motion is predictable in time. The motion estimation algorithm is phase-based and uses two or three field-images to achieve motion estimates with sub-pixel accuracy. To handle non-constant motion and the specific characteristics of the field-image to be coded, the initially predicted image is refined using forward motion compensation, based on block-matching. Tests show that this approach achieves higher PSNR than forward block-based motion estimation, when coding the residual with the same coder. The subjective performance is also better.
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- Ebenhag, Sven-Christian, 1976, et al.
(author)
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Time transfer using an asynchronous computer network: Results from three weeks of measurements
- 2007
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In: European Frequency and Time Forum, 29/5 - 1/6, Geneva, CH.
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Conference paper (peer-reviewed)abstract
- We have performed a time transfer experimentbetween two atomic clocks, over a distance of approximately 75km using an 10 Gbit/s asynchronous fiber-optic computernetwork. The time transfer was accomplished through passivelistening on existing data traffic and a pilot sequence in the SDHbit stream. In order to assess the fiber-link clock comparison, wesimultaneously compared the clocks using a GPS carrier phaselink. The standard deviation of the difference between the twotime transfer links over the three-week time period was 243 ps.
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- Fredenberg, Erik, et al.
(author)
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X-ray attenuation of adipose breast tissue : In-vitro and in-vivo measurements using spectral imaging
- 2015
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In: MEDICAL IMAGING 2015: PHYSICS OF MEDICAL IMAGING. - : SPIE. - 9781628415025
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Conference paper (peer-reviewed)abstract
- The development of new x-ray imaging techniques often requires prior knowledge of tissue attenuation, but the sources of such information are sparse. We have measured the attenuation of adipose breast tissue using spectral imaging, in vitro and in vivo. For the in-vitro measurement, fixed samples of adipose breast tissue were imaged on a spectral mammography system, and the energy-dependent x-ray attenuation was measured in terms of equivalent thicknesses of aluminum and poly-methyl methacrylate (PMMA). For the in-vivo measurement, a similar procedure was applied on a number of spectral screening mammograms. The results of the two measurements agreed well and were consistent with published attenuation data and with measurements on tissue-equivalent material.
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