| 1. |
- Canovic, Sead, 1979, et al.
(författare)
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CVD TiC/alumina and TiN/alumina multilayer coatings grown on sapphire single crystals
- 2010
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Ingår i: International Journal of Refractory Metals & Hard Materials. - : Elsevier BV. - 0263-4368. ; 28:2, s. 163-173
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Tidskriftsartikel (refereegranskat)abstract
- Multilayers of TiC/alpha-Al2O3 and TiN/kappa-Al2O3, consisting of three (1 mm thick) alumina layers separated by thin TiC or TiN (similar to 20 nm thick) layers, have been deposited onto c- and r-surfaces of single crystals of alpha-Al2O3 by chemical vapour deposition (CVD). The aim of this paper is to describe and compare the detailed microstructure of the different multilayer coatings by using transmission electron microscopy (TEM). The general microstructure of the alumina layers is very different when deposited onto different surfaces of alpha-Al2O3 single crystal substrates. On the c-surface the alumina layers grew evenly resulting in growth of single crystal layers of TiC or TiN and alumina throughout the coating. However, when deposited on the r-surface the alumina layers generally grow unevenly. The kappa -> alpha transformation occurs in TiN/kappa-Al2O3 multilayer coatings when deposited on both c- and r-surface substrates. In each layer the transformation starts at the interfacial pores in the upper part and proceeds inwards. The inner layer starts to transform first before the transformation proceeds to the outer layers. The microstructure of the transformed alpha-Al2O3 layers is different compared to as-deposited alpha-Al2O3, e.g. several voids and dislocations are present within the transformed alpha-Al2O3 layers. No pores were observed within the as-deposited alumina layers while a small number of pores was observed at the interfaces below the TiC and TiN layers. However, linkage of pores was observed within the transformed alpha-Al2O3 layers. There are also pores present in the substrate below the innermost TiC and TiN layers. It is believed that they are formed due to chemical etching during the deposition of the TiC and TiN layers. Single crystal TiC/alumina and TiN/alumina layers grow epitaxially on the c-surface substrates with close-packed planes growing on close-packed planes. On the r-surface, epitaxy is present only at some rare locations in alpha(r-sub)-TiC/Al2O3. However, in alpha(r-sub)-TiN/Al2O3 no epitaxy was observed. (C) 2009 Elsevier Ltd. All rights reserved.
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| 2. |
- Gustafsson, Agnetha, et al.
(författare)
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Evaluation of attenuation corrections using Monte Carlo simulated lung SPECT
- 1998
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 1361-6560 .- 0031-9155. ; 43:8, s. 2325-2336
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Tidskriftsartikel (refereegranskat)abstract
- SPECT (single photon emission computed tomography) images are distorted by photon attenuation. The effect is complex in the thoracic region due to different tissue densities. This study compares the effect on the image homogeneity of two different methods of attenuation correction in lung SPECT; one pre-processing and one post-processing method. This study also investigates the impact of attenuation correction parameters such as lung contour, body contour, density of the lung tissue and effective attenuation coefficient. The Monte Carlo technique was used to simulate SPECT studies of a digital thorax phantom containing a homogeneous activity distribution in the lung. Homogeneity in reconstructed images was calculated as the coefficient of variation (CV). The isolated effect of the attenuation correction was assessed by normalizing pixel values from the attenuation corrected lung by pixel values from the lung with no attenuation effects. Results show that the CV decreased from 12.8% with no attenuation correction to 4.4% using the post-processing method and true densities in the thoracic region. The impact of variations in the definition of the body contour was found to be marginal while the corresponding effect of variations in the lung contour was substantial
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| 3. |
- Körning-Ljungberg, Jessica, et al.
(författare)
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‘What’s in a name?’ ‘No more than when it's mine own’. Evidence from auditory oddball distraction
- 2014
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Ingår i: Acta Psychologica. - : Elsevier BV. - 0001-6918 .- 1873-6297. ; 150, s. 161-6
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Tidskriftsartikel (refereegranskat)abstract
- Research of the distractor value of hearing the own name has shown that this self-referring stimulus captures attention in an involuntary fashion and create distraction. The behavioral studies are few and the outcomes are not always clear cut. In this study the distraction by own name compared to a control name was investigated by using a cross-modal oddball task in two experiments. In the first experiment, thirty-nine participants were conducting a computerized categorization task while exposed to, to-be ignored own and matched control names (controlling for familiarity, gender and number of syllables) as unexpected auditory deviant stimulus (12.5% trials for each name category) and a sine wave tone as a standard stimulus (75% of the trials). In the second experiment, another group of thirty-nine participants completed the same task but with the additional deviant stimulus of an irrelevant word added (10% trials for each deviant type and 70% trials with the standard stimulus). Results showed deviant distraction by exposure to both the irrelevant word, own and the control name compared to the standard tone but no differences were found showing that the own name captured attention and distracted the participants more than an irrelevant word or a control name. The results elucidate the role of the own name as a potent auditory distractor and possible limitations with its theoretical significance for general theories of attention are discussed.
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| 4. |
- Parmentier, Fabrice B.R., et al.
(författare)
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Behavioral distraction by auditory novelty is not only about novelty : the role of the distracter’s informational value
- 2010
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Ingår i: Cognition. - : Elsevier BV. - 0010-0277 .- 1873-7838. ; 115:3, s. 504-511
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Tidskriftsartikel (refereegranskat)abstract
- Unexpected events often distract us. In the laboratory, novel auditory stimuli have been shown to capture attention away from a focal visual task and yield specific electrophysiological responses as well as a behavioral cost to performance. Distraction is thought to follow ineluctably from the sound’s low probability of occurrence or, put more simply, its unexpected occurrence. Our study challenges this view with respect to behavioral distraction and argues that past research failed to identify the informational value of sound as a mediator of novelty distraction. We report an experiment showing that (1) behavioral novelty distraction is only observed when the sound announces the occurrence and timing of an upcoming visual target (as is the case in all past research); (2) that no such distraction is observed for deviant sounds conveying no such information; and that (3) deviant sounds can actually facilitate performance when these, but not the standards, convey information. We conclude that behavioral novelty distraction, as observed in oddball tasks, is observed in the presence of novel sounds but only when the cognitive system can take advantage of the auditory distracters to optimize performance.
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