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- Hansson, Frida, et al.
(författare)
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Exit of pediatric pre-B acute lymphoblastic leukaemia cells from the bone marrow to the peripheral blood is not associated with cell maturation or alterations in gene expression
- 2008
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Ingår i: Molecular Cancer. - : Springer Science and Business Media LLC. - 1476-4598. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Background: Childhood pre-B acute lymphoblastic leukemia (ALL) is a bone marrow (BM) derived disease, which often disseminates out of the BM cavity, where malignant cells to a variable degree can be found circulating in the peripheral blood (PB). Normal pre-B cells are absolutely dependent on BM stroma for survival and differentiation. It is not known whether transformed pre-B ALL cells retain any of this dependence, which possibly could impact on drug sensitivity or MRD measurements. Results: Pre-B ALL cells, highly purified by a novel method using surface expression of CD19 and immunoglobulin light chains, from BM and PB show a very high degree of similarity in gene expression patterns, with differential expression of vascular endothelial growth factor (VEGF) as a notable exception. In addition, the cell sorting procedure revealed that in 2 out of five investigated patients, a significant fraction of the malignant cells had matured beyond the pre-B cell stage. Conclusion: The transition of ALL cells from the BM into the circulation does not demand, or result in, major changes of gene expression pattern. This might indicate an independence of BM stroma on the part of transformed pre-B cells, which contrasts with that of their normal counterparts. © 2008 Hansson et al, licensee BioMed Central Ltd.
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- Nyström, Ida-Linn, et al.
(författare)
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Effect of peat addition to woody biomass pellets on slagging characteristics during combustion in residential pellet burners
- 2009
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Ingår i: From research to industry and markets. - Florence : ETA - Renewable Energies. ; , s. 1400-1405
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Konferensbidrag (refereegranskat)abstract
- Upgraded biofuels as pellets, briquettes and powder are today commonly used in small as well as large scale appliances. In order to cover a great fuel demand new materials as bark, whole tree assortments and peat are introduced. These materials have higher ash content why they are potentially more problematic compared with stem wood. Ash related problems in the combustion device, e.g. fouling, slagging and corrosion may occur from the incombustible leftover i.e. the fuel ash. The objective of the present work was to determine the effect on slagging characteristics when co-pelletizing peat into woody biomass. In this project woody biomass (pine and spruce 50/50) has been co-pelletized with three different mixtures (low, medium and high) of peat; peat A with high ash and high Si content and peat B with low ash and a relatively high Ca/Si content. There were totally 6 mixed assortments in which softwood sawdust and energy wood each represented the biomass in 3 samples respectively. The experiments were carried out in a commercial underfed pellet burner (20 kW) installed in a reference boiler. X-ray diffraction (XRD) was used to characterize the phase composition and scanning electron microscopy combined with energy dispersive X-ray analysis (SEM-EDS) were utilized in order to characterize the elemental distribution and morphology of the collected slag deposits and bottom ashe. The slagging tendency showed an obvious increment when adding peat into the woody biomasses. Especially the ash- and relatively Ca-poor sawdust fuel was generally more sensitive for the different peat assortments. Co-firing of peat A (high ash- and Si content) resulted in the most severe slagging tendency, where four out of six experiments led to a total shut down of the burner due to the slagging. The slagging tendency was significantly lower when adding peat B (ash poor and relatively high (Ca/Si ratio) into the woody biomass fuels. A significant increment of the Si, Al and Fe content and a significant decrement of the Ca content could be seen when increasing the mixing content of peat A in both woody biomasses. The slag from the peat B mixtures had a slightly higher Ca content compared with the Si content and a clearly higher Ca content compared with the peat A mixtures. When introducing the relatively silicon rich Peat A to the woody biomasses the slagging tendency increased because high temperature melting Ca-Mg oxides reacts to form more low temperature melting Ca-Al-K silicates. In the case of the more ash poor peat B, with relatively high Ca/Si ratio, there were still Ca-Mg oxides left in the bottom ash i.e. a less amount of sticky low temperature melting Ca-Al-K silicates were formed.
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| 9. |
- Nyström, Marcus, et al.
(författare)
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Multiple description image coding using regions of interest
- 2007
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Ingår i: Proceedings, 41st Asilomar Conference on Signals, Systems, and Computers, November 4-7, 2007. ; , s. 925-929
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Konferensbidrag (refereegranskat)abstract
- A multiple description (MD) coding scheme encodes an image such that each description alone yields an acceptable reconstruction quality, and the descriptions together render increasingly better approximations of the image. Traditionally, each description contributes equally to the reconstruction quality throughout the image. This is inefficient from a coding perspective since all descriptions largely represent similar source information. We suggest a novel region of interest (ROI) based MD coding scheme with two descriptions and two ROIs, such that each ROI is coded into a separate description. The impact this scheme has on visual reconstruction quality and coding efficiency is investigated. We argue that ROI based MD coding is beneficial at low bit rates since it (i) introduces little redundancy between the descriptions with practically no loss in quality at the central decoder, and (ii) still produces useful side descriptions. Extensions to video coding are discussed in the concluding section.
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| 10. |
- Nyström, Marcus
(författare)
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Off-line Foveated Compression and Scene Perception: An Eye-Tracking Approach
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With the continued growth of digital services offering storage and communication of pictorial information, the need to efficiently represent this information has become increasingly important, both from an information theoretic and a perceptual point of view. There has been a recent interest to design systems for efficient representation and compression of image and video data that take the features of the human visual system into account. One part of this thesis investigates whether knowledge about viewers' gaze positions as measured by an eye-tracker can be used to improve compression efficiency of digital video; regions not directly looked at by a number of previewers are lowpass filtered. This type of video manipulation is called off-line foveation. The amount of compression due to off-line foveation is assessed along with how it affects new viewers' gazing behavior as well as subjective quality. We found additional bitrate savings up to 50% (average 20%) due to off-line foveation prior to compression, without decreasing the subjective quality. In off-line foveation, it would be of great benefit to algorithmically predict where viewers look without having to perform eye-tracking measurements. In the first part of this thesis, new experimental paradigms combined with eye-tracking are used to understand the mechanisms behind gaze control during scene perception, thus investigating the prerequisites for such algorithms. Eye-movements are recorded from observers viewing contrast manipulated images depicting natural scenes under a neutral task. We report that image semantics, rather than the physical image content itself, largely dictates where people choose to look. Together with recent work on gaze prediction in video, the results in this thesis give only moderate support for successful applicability of algorithmic gaze prediction for off-line foveated video compression.
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