| 11. |
- Ljung, Patric, 1968-, et al.
(författare)
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Full Body Virtual Autopsies Using A State-of-the-art Volume Rendering Pipeline
- 2006
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Ingår i: IEEE Transactions on Visualization and Computer Graphics. - 1077-2626 .- 1941-0506. ; 12:5, s. 869-876
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a procedure for virtual autopsies based on interactive 3D visualizations of large scale, high resolutiondata from CT-scans of human cadavers. The procedure is described using examples from forensic medicine and the added valueand future potential of virtual autopsies is shown from a medical and forensic perspective. Based on the technical demands ofthe procedure state-of-the-art volume rendering techniques are applied and refined to enable real-time, full body virtual autopsiesinvolving gigabyte sized data on standard GPUs. The techniques applied include transfer function based data reduction using levelof-detail selection and multi-resolution rendering techniques. The paper also describes a data management component for large,out-of-core data sets and an extension to the GPU-based raycaster for efficient dual TF rendering. Detailed benchmarks of thepipeline are presented using data sets from forensic cases.
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| 12. |
- Lundin (Palmerius), Karljohan, 1977-, et al.
(författare)
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Enabling design and interactive selection of haptic modes
- 2007
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Ingår i: Virtual Reality. - : Springer Science and Business Media LLC. - 1359-4338 .- 1434-9957.
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Tidskriftsartikel (refereegranskat)abstract
- The ever increasing size and complexity of volumetric data in a wide range of disciplines makes it useful to augment volume visualization tools with alternative modalities. Studies have shown that introducing haptics can significantly increase both exploration speed and precision. It is also capable of conveying material properties of data and thus has great potential to improve user performance in volume data exploration. In this paper we describe how recent advances in volume haptics can be used to build haptic modes-building blocks for haptic schemes. These modes have been used as base components of a toolkit allowing for more efficient development of haptic prototypes and applications. This toolkit allows interactive construction, configuration and fine-tuning of both visual and haptic representations of the data. The technology is also used in a pilot study to determine the most important issues and aspects in haptic volume data interaction and exploration, and how the use of haptic modes can facilitate the implementation of effective haptic schemes.
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| 13. |
- Lundström, Claes, 1973-, et al.
(författare)
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The alpha-histogram: Using Spatial Coherence to Enhance Histograms and Transfer Function Design
- 2006
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Ingår i: Proceedings Eurographics/IEEE Symposium on Visualization 2006, Lisbon, Portugal. ; , s. 227-234
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The high complexity of Transfer Function (TF) design is a major obstacle to widespread routine use of Direct Volume Rendering, particularly in the case of medical imaging. Both manual and automatic TF design schemes would benefit greatly from a fast and simple method for detection of tissue value ranges. To this end, we introduce the a-histogram, an enhancement that amplifies ranges corresponding to spatially coherent materials. The properties of the a-histogram have been explored for synthetic data sets and then successfully used to detect vessels in 20 Magnetic Resonance angiographies, proving the potential of this approach as a fast and simple technique for histogram enhancement in general and for TF construction in particular.
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| 14. |
- Lundström, Claes, 1973-, et al.
(författare)
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Uncertainty Visualization in Medical Volume Rendering Using Probabilistic Animation
- 2007
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Ingår i: IEEE Transactions on Visualization and Computer Graphics. - 1077-2626 .- 1941-0506. ; 13:6, s. 1648-1655
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Tidskriftsartikel (refereegranskat)abstract
- Direct volume rendering has proved to be an effective visualization method for medical data sets and has reached wide-spread clinical use. The diagnostic exploration, in essence, corresponds to a tissue classification task, which is often complex and time-consuming. Moreover, a major problem is the lack of information on the uncertainty of the classification, which can have dramatic consequences for the diagnosis. In this paper this problem is addressed by proposing animation methods to convey uncertainty in the rendering. The foundation is a probabilistic Transfer Function model which allows for direct user interaction with the classification. The rendering is animated by sampling the probability domain over time, which results in varying appearance for uncertain regions. A particularly promising application of this technique is a "sensitivity lens" applied to focus regions in the data set. The methods have been evaluated by radiologists in a study simulating the clinical task of stenosis assessment, in which the animation technique is shown to outperform traditional rendering in terms of assessment accuracy.
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| 15. |
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| 16. |
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| 17. |
- Malmberg Persson, Kärstin, et al.
(författare)
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När iskanten tog paus i Vimmerby
- 2008
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Ingår i: Geologiskt forum. ; 15:60, s. 12-15
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 18. |
- Nilsson, Anders, et al.
(författare)
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Behavioral interference and facilitation in the foraging cycle shape the functional response
- 2007
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 18:2, s. 354-357
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Tidskriftsartikel (refereegranskat)abstract
- Individual forager behaviors should affect per capita intake rates and thereby population and consumer-resource properties. We consider and incorporate conspecific facilitation and interference during the separate foraging-cycle stages in a functional response model that links individual behavioral interactions with consumer-resource processes. Our analyses suggest that failing to properly consider and include all effects of behavioral interactions on foraging-cycle stage performances may either over- or underestimate effects of interactions on the shape of both functional responses and predator zero-growth isoclines. Incorporation of prey- and predator-dependent interactions among foragers in the model produces predator isoclines with potentials for highly complex consumer-resource dynamics. Facilitation and interference during the foraging cycle are therefore suggested as potent behavioral mechanisms to cause patterns of community dynamics. We emphasize that correct estimations of interaction-mediated foraging-cycle efficiencies should be considered in empirical and theoretical attempts to further our understanding of the mechanistic link between social behaviors and higher order processes.
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| 19. |
- Olofsson, Anders, et al.
(författare)
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Amide solvent protection analysis demonstrates that amyloid-beta(1-40) and amyloid-beta(1-42) form different fibrillar structures under identical conditions.
- 2007
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Ingår i: Biochem J. - 1470-8728. ; 404:1, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- AD (Alzheimer's disease) is a neurodegenerative disorder characterized by self-assembly and amyloid formation of the 39–43 residue long Ab (amyloid-b)-peptide. The most abundant species, Ab(1–40) and Ab(1–42), are both present within senile plaques, but Ab(1–42) peptides are considerably more prone to self-aggregation and are also essential for the development of AD. To understand the molecular and pathological mechanisms behind AD, a detailed knowledge of the amyloid structures of Ab-peptides is vital. In the present study we have used quenched hydrogen/deuterium-exchange NMR experiments to probe the structure of Ab(1–40) fibrils. The fibrils were prepared and analysed identically as in our previous study on Ab(1–42) fibrils, allowing a direct comparison of the two fibrillar structures. The solvent protection pattern of Ab(1–40) fibrils revealed two well-protected regions, consistent with a structural arrangement of two b-strands connected with a bend. This protection pattern partly resembles the pattern found in Ab(1–42) fibrils, but the Ab(1–40) fibrils display a significantly increased protection for the N-terminal residues Phe4–His14, suggesting that additional secondary structure is formed in this region. In contrast, the C-terminal residues Gly37–Val40 show a reduced protection that suggests a loss of secondary structure in this region and an altered filament assembly. The differences between the present study and other similar investigations suggest that subtle variations in fibril-preparation conditions may significantly affect the fibrillar architecture.
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| 20. |
- Olofsson, Anders, et al.
(författare)
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Quenched hydrogen/deuterium exchange NMR characterization of amyloid-β peptide aggregates formed in the presence of Cu2+ or Zn2
- 2009
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Ingår i: The FEBS Journal. - : Wiley InterScience. - 1742-464X .- 1742-4658. ; 276:15, s. 4051-4060
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease, a neurodegenerative disorder causing synaptic impairment and neuronal cell death, is strongly correlated with aggregation of the amyloid-β peptide (Aβ). Divalent metal ions such as Cu2+ and Zn2+ are known to significantly affect the rate of aggregation and morphology of Aβ assemblies in vitro and are also found at elevated levels within cerebral plaques in vivo. The present investigation characterized the architecture of the aggregated forms of Aβ(1–40) and Aβ(1–42) in the presence or absence of either Cu2+ or Zn2+ using quenched hydrogen/deuterium exchange combined with solution NMR spectroscopy. The NMR analyses provide a quantitative and residue-specific structural characterization of metal-induced Aβ aggregates, showing that both the peptide sequence and the type of metal ion exert an impact on the final architecture. Common features among the metal-complexed peptide aggregates are two solvent-protected regions with an intervening minimum centered at Asn27, and a solvent-accessible N-terminal region, Asp1–Lys16. Our results suggest that Aβ in complex with either Cu2+ or Zn2+ can attain an aggregation-prone β-strand–turn–β-strand motif, similar to the motif found in fibrils, but where the metal binding to the N-terminal region guides the peptide into an assembly distinctly different from the fibril form.
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