| 1. |
- Wernemyr, Claes, 1949, et al.
(författare)
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Users’ experience of a virtual reality architectural model compared with users’ experience of the completed building
- 2003
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Ingår i: Proceedings of the 1st international conference on advanced research in virtual and rapid prototyping. ; , s. 363-370, s. 363-370
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Konferensbidrag (refereegranskat)abstract
- This research investigated how the employees of a company experienced a VR-model of an office building that was to be their future work place and how that VR-experience com¬pared with the employees’ experience of the completed building. About two years after the VR-showings the building was completed and the staff had moved into the building. The results for the employees who saw the VR-presentation for the Semantic environment de¬scrip¬tion scale (SMB) comparing the experiences of the VR-model with the experiences of the completed real building suggested that the experience of the VR-model gave a fairly accurate representation of the experience of the real building However, the reactions to the VR-model were more appreciative after the VR-show as compared with when the VR-model was compared with the real building.
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| 2. |
- Schirmer, M. D., et al.
(författare)
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White matter hyperintensity quantification in large-scale clinical acute ischemic stroke cohorts - The MRI-GENIE study
- 2019
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Ingår i: Neuroimage-Clinical. - : Elsevier BV. - 2213-1582. ; 23
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Tidskriftsartikel (refereegranskat)abstract
- White matter hyperintensity (WMH) burden is a critically important cerebrovascular phenotype linked to prediction of diagnosis and prognosis of diseases, such as acute ischemic stroke (AIS). However, current approaches to its quantification on clinical MRI often rely on time intensive manual delineation of the disease on T2 fluid attenuated inverse recovery (FLAIR), which hinders high-throughput analyses such as genetic discovery. In this work, we present a fully automated pipeline for quantification of WMH in clinical large-scale studies of AIS. The pipeline incorporates automated brain extraction, intensity normalization and WMH segmentation using spatial priors. We first propose a brain extraction algorithm based on a fully convolutional deep learning architecture, specifically designed for clinical FLAIR images. We demonstrate that our method for brain extraction outperforms two commonly used and publicly available methods on clinical quality images in a set of 144 subject scans across 12 acquisition centers, based on dice coefficient (median 0.95; inter-quartile range 0.94-0.95; p < 0.01) and Pearson correlation of total brain volume (r = 0.90). Subsequently, we apply it to the large-scale clinical multi-site MRI-GENIE study (N = 2783) and identify a decrease in total brain volume of -2.4 cc/year. Additionally, we show that the resulting total brain volumes can successfully be used for quality control of image preprocessing. Finally, we obtain WMH volumes by building on an existing automatic WMH segmentation algorithm that delineates and distinguishes between different cerebrovascular pathologies. The learning method mimics expert knowledge of the spatial distribution of the WMH burden using a convolutional auto-encoder. This enables successful computation of WMH volumes of 2533 clinical AIS patients. We utilize these results to demonstrate the increase of WMH burden with age (0.950 cc/year) and show that single site estimates can be biased by the number of subjects recruited.
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| 3. |
- Bender, Michael A., et al.
(författare)
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The minimum backlog problem
- 2015
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Ingår i: Theoretical Computer Science. - : ELSEVIER SCIENCE BV. - 0304-3975 .- 1879-2294. ; 605, s. 51-61
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Tidskriftsartikel (refereegranskat)abstract
- We study the minimum backlog problem (MBP). This online problem arises, e.g., in the context of sensor networks. We focus on two main variants of MBP. The discrete MBP is a 2-person game played on a graph G = (V, E). The player is initially located at a vertex of the graph. In each time step, the adversary pours a total of one unit of water into cups that are located on the vertices of the graph, arbitrarily distributing the water among the cups. The player then moves from her current vertex to an adjacent vertex and empties the cup at that vertex. The players objective is to minimize the backlog, i.e., the maximum amount of water in any cup at any time. The geometric MBP is a continuous-time version of the MBP: the cups are points in the two-dimensional plane, the adversary pours water continuously at a constant rate, and the player moves in the plane with unit speed. Again, the players objective is to minimize the backlog. We show that the competitive ratio of any algorithm for the MBP has a lower bound of Omega (D), where D is the diameter of the graph (for the discrete MBP) or the diameter of the point set (for the geometric MBP). Therefore we focus on determining a strategy for the player that guarantees a uniform upper bound on the absolute value of the backlog. For the absolute value of the backlog there is a trivial lower bound of Omega (D), and the deamortization analysis of Dietz and Sleator gives an upper bound of O (D log N) for N cups. Our main result is a tight upper bound for the geometric MBP: we show that there is a strategy for the player that guarantees a backlog of O(D), independently of the number of cups. We also study a localized version of the discrete MBP: the adversary has a location within the graph and must act locally (filling cups) with respect to his position, just as the player acts locally (emptying cups) with respect to her position. We prove that deciding the value of this game is PSPACE-hard. (C) 2015 Elsevier B.V. All rights reserved.
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| 4. |
- Chen, H., et al.
(författare)
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Unprecedented non-hysteretic superelasticity of [001]-oriented NiCoFeGa single crystals
- 2020
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Ingår i: Nature Materials. - : Nature Research. - 1476-1122 .- 1476-4660.
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Tidskriftsartikel (refereegranskat)abstract
- Superelasticity associated with the martensitic transformation has found a broad range of engineering applications1,2. However, the intrinsic hysteresis3 and temperature sensitivity4 of the first-order phase transformation significantly hinder the usage of smart metallic components in many critical areas. Here, we report a large superelasticity up to 15.2% strain in [001]-oriented NiCoFeGa single crystals, exhibiting non-hysteretic mechanical responses, a small temperature dependence and high-energy-storage capability and cyclic stability over a wide temperature and composition range. In situ synchrotron X-ray diffraction measurements show that the superelasticity is correlated with a stress-induced continuous variation of lattice parameter accompanied by structural fluctuation. Neutron diffraction and electron microscopy observations reveal an unprecedented microstructure consisting of atomic-level entanglement of ordered and disordered crystal structures, which can be manipulated to tune the superelasticity. The discovery of the large elasticity related to the entangled structure paves the way for exploiting elastic strain engineering and development of related functional materials.
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| 5. |
- Efrat, Alon, et al.
(författare)
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Improved Approximation Algorithms for Relay Placement
- 2016
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Ingår i: ACM Transactions on Algorithms. - : ACM Press. - 1549-6325 .- 1549-6333. ; 12:2, s. 20-
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Tidskriftsartikel (refereegranskat)abstract
- In the relay placement problem, the input is a set of sensors and a number r >= 1, the communication range of a relay. In the one-tier version of the problem, the objective is to place a minimum number of relays so that between every pair of sensors there is a path through sensors and/or relays such that the consecutive vertices of the path are within distance r if both vertices are relays and within distance 1 otherwise. The two-tier version adds the restrictions that the path must go through relays, and not through sensors. We present a 3.11-approximation algorithm for the one-tier version and a polynomial-time approximation scheme (PTAS) for the two-tier version. We also show that the one-tier version admits no PTAS, assuming P not equal NP.
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| 6. |
- Hsu-Kim, Heileen, et al.
(författare)
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Challenges and opportunities for managing aquatic mercury pollution in altered landscapes
- 2018
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 47:2, s. 141-169
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Tidskriftsartikel (refereegranskat)abstract
- The environmental cycling of mercury (Hg) can be affected by natural and anthropogenic perturbations. Of particular concern is how these disruptions increase mobilization of Hg from sites and alter the formation of monomethylmercury (MeHg), a bioaccumulative form of Hg for humans and wildlife. The scientific community has made significant advances in recent years in understanding the processes contributing to the risk of MeHg in the environment. The objective of this paper is to synthesize the scientific understanding of how Hg cycling in the aquatic environment is influenced by landscape perturbations at the local scale, perturbations that include watershed loadings, deforestation, reservoir and wetland creation, rice production, urbanization, mining and industrial point source pollution, and remediation. We focus on the major challenges associated with each type of alteration, as well as management opportunities that could lessen both MeHg levels in biota and exposure to humans. For example, our understanding of approximate response times to changes in Hg inputs from various sources or landscape alterations could lead to policies that prioritize the avoidance of certain activities in the most vulnerable systems and sequestration of Hg in deep soil and sediment pools. The remediation of Hg pollution from historical mining and other industries is shifting towards in situ technologies that could be less disruptive and less costly than conventional approaches. Contemporary artisanal gold mining has well-documented impacts with respect to Hg; however, significant social and political challenges remain in implementing effective policies to minimize Hg use. Much remains to be learned as we strive towards the meaningful application of our understanding for stakeholders, including communities living near Hg-polluted sites, environmental policy makers, and scientists and engineers tasked with developing watershed management solutions. Site-specific assessments of MeHg exposure risk will require new methods to predict the impacts of anthropogenic perturbations and an understanding of the complexity of Hg cycling at the local scale.
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| 7. |
- Mitchell-Thomas, R. C., et al.
(författare)
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Broadband Metasurface for Surface Wave Lenses
- 2016
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Ingår i: 2016 URSI INTERNATIONAL SYMPOSIUM ON ELECTROMAGNETIC THEORY (EMTS). - : IEEE. - 9781509025022 ; , s. 605-606
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Konferensbidrag (refereegranskat)abstract
- This paper presents the design of a metasurface that exhibits glide symmetry. This allows the metasurface to support a mode that is confined to the surface for a broad band of frequencies. In addition it is shown that the mode index of such surfaces depends only weakly on the frequency over a given range. We then propose these structures as a practical solution to the fabrication of broadband surface-wave lenses designed using quasi-conformal transformation optics technique.
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| 8. |
- Adrianto, Lugas Raka, et al.
(författare)
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How can LCA include prospective elements to assess emerging technologies and system transitions? The 76th LCA Discussion Forum on Life Cycle Assessment, 19 November 2020
- 2021
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Ingår i: International Journal of Life Cycle Assessment. - : Springer Science and Business Media LLC. - 1614-7502 .- 0948-3349. ; 26:8, s. 1541-1544
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Tidskriftsartikel (refereegranskat)abstract
- This paper summarizes the 76th LCA Discussion Forum end its main findings. Main issues when addressing emerging technologies identified were: the lack of primary data, the need for (shared) future background scenarios and (guidlines for) a common methodology. The following recommendations have been derived by the organizers: 1) Specific foreground inventories are always tailor-made, but consistency can be improved through lists of mandatory considerations. 2) Continue sharing (future) technology data and proxy processes, that can be readily replicated to new studies and assist in developing inventories. 3) Streamline and unify the process of including scenarios for background systems. New approaches may provide first important solutions to efficiently include consistent future scenarios in prospective LCA.
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| 9. |
- Camacho, Miguel, et al.
(författare)
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Designer surface plasmon dispersion on a one-dimensional periodic slot metasurface with glide symmetry
- 2017
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Ingår i: Optics Letters. - : Optical Society of America. - 0146-9592 .- 1539-4794. ; 42:17, s. 3375-3378
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Tidskriftsartikel (refereegranskat)abstract
- In this Letter, we explore the dispersion of spoof surface plasmons supported by a single-layer glide-symmetric structure. This structure consists of an infinitely long double-notched slot perforated in a metal layer. The presence of a degeneracy of the two lowest-order modes at the Brillouin zone boundary, which have non-zero group velocity is explained and experimentally demonstrated. Further, the dependence of the band structure when glide-symmetric configuration is broken is also explored.
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| 10. |
- Jones, Mitchell P., et al.
(författare)
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Mycomining: perspective on fungi as scavengers of scattered metal, mineral, and rare earth element resources
- 2024
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Ingår i: RSC Sustainability. - : Royal Society of Chemistry. - 2753-8125. ; 2:5, s. 1350-1357
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Forskningsöversikt (refereegranskat)abstract
- Mining provides raw materials critical to our energy, agriculture, infrastructure, and technology but is associated with many environmental challenges. Resource recovery alternatives like urban mining rely on inconsistent supply streams and complicated disassembly and sorting, while extreme mining alternatives such as deep sea and space mining are potentially even less sustainable than traditional mining. This perspective investigates biological mining with emphasis on the potential of fungi for scavenging metals, minerals, and rare earth elements. “Mycomining” produces only biomass-based organic waste and can offer more versatile growth conditions than phytomining using hyperaccumulating plants including substrates ranging from soil, wood, water, and rock to living organisms and dark, space-restricted, or extreme i.e., pH levels, high salt, acidic, radioactive environments. This concept could represent a useful supplement to urban and phytomining to offset demand for traditional mining and is particularly viable when conventional mining may be inefficient or uneconomical i.e., with low-grade ores and sites unsuited to traditional mining for geographical, political, or social reasons.
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