| 1. |
- Aalders, Johannes Theodor, et al.
(author)
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The Making and Unmaking of a Megaproject: Contesting Temporalities along the LAPSSET Corridor in Kenya
- 2021
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In: Antipode. - : Wiley. - 0066-4812 .- 1467-8330. ; 53:5, s. 1273-1293
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Journal article (peer-reviewed)abstract
- In this paper, we show how communities in Northern Kenya proactively engage an unfolding megaproject and the temporalities it evokes—the Lamu Port South Sudan Ethiopia Transport Corridor (LAPSSET). We argue that the latitude communities have in contending with megaprojects is broader and more dynamic than passive reception of or outright resistance against the futures promised. By introducing the concepts of entangling and fraying, we emphasise the agency communities create for themselves by appreciating their strategies and expressions of stabilising or troubling the “megaproject”. While entangling refers to practices through which communities attach additional features to an otherwise rather stable vision of its “meganess”, fraying, in contrast, describes the strands that splice off towards different spatio‐temporal imaginaries. We discuss these practices in four instances of engaging LAPSSET: constructing temporary homes at project sites; engaging in land reform; disputing land acquisition at oil exploration sites; and contesting a planned resort city.
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| 2. |
- Gu, Xuan, et al.
(author)
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Bayesian Diffusion Tensor Estimation with Spatial Priors
- 2017
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In: CAIP 2017. - Cham : Springer International Publishing. - 9783319646893 - 9783319646886 ; , s. 372-383
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Conference paper (peer-reviewed)abstract
- Spatial regularization is a technique that exploits the dependence between nearby regions to locally pool data, with the effect of reducing noise and implicitly smoothing the data. Most of the currently proposed methods are focused on minimizing a cost function, during which the regularization parameter must be tuned in order to find the optimal solution. We propose a fast Markov chain Monte Carlo (MCMC) method for diffusion tensor estimation, for both 2D and 3D priors data. The regularization parameter is jointly with the tensor using MCMC. We compare FA (fractional anisotropy) maps for various b-values using three diffusion tensor estimation methods: least-squares and MCMC with and without spatial priors. Coefficient of variation (CV) is calculated to measure the uncertainty of the FA maps calculated from the MCMC samples, and our results show that the MCMC algorithm with spatial priors provides a denoising effect and reduces the uncertainty of the MCMC samples.
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| 3. |
- Hageback, Johanna, et al.
(author)
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Climate variability and land-use change in Danangou watershed, China : Examples of small-scale farmers' adaptation
- 2005
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In: Climatic Change. - : Springer Science and Business Media LLC. - 0165-0009 .- 1573-1480. ; 72:1-2, s. 189-212
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Journal article (peer-reviewed)abstract
- With global concern on climate change impacts, developing countries are given special attention due their susceptibility. In this paper, change and variability in climate, land use and farmers’ perception, adaptation and response to change are examined in Danangou watershed in the Chinese Loess Plateau. The first focus is to look at how climate data recorded at meteorological stations recently have evolved, and how farmers perceived these changes. Further, we want to see how the farmers respond and adapt to climate variability and what the resulting impact on land use is. Finally, other factors causing change in land use are considered. Local precipitation and temperature instrumental data and interview data from farmers were used. The instrumental data shows that the climate is getting warmer and drier, the latter despite large interannual variability. The trend is seen on the local and regional level. Farmers’ perception of climatic variability corresponds well with the data record. During the last 20 years, the farmers have become less dependent on agriculture by adopting a more diversified livelihood. This adaptation makes them less vulnerable to climate variability. It was found that government policies and reforms had a stronger influence on land use than climate variability. Small-scale farmers should therefore be considered as adaptive to changing situations, planned and non-consciously planned.
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| 4. |
- Hageback, Johanna, et al.
(author)
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Climate variability and land-use change in Danangou watershed, China
- 2005
-
In: Climatic Change. - : Springer Science and Business Media LLC. - 1573-1480 .- 0165-0009. ; 72:1-2, s. 189-212
-
Journal article (peer-reviewed)abstract
- With global concern on climate change impacts, developing countries are given special attention due their susceptibility. In this paper, change and variability in climate, land use and farmers’ perception, adaptation and response to change are examined in Danangou watershed in the Chinese Loess Plateau. The first focus is to look at how climate data recorded at meteorological stations recently have evolved, and how farmers perceived these changes. Further, we want to see how the farmers respond and adapt to climate variability and what the resulting impact on land use is. Finally, other factors causing change in land use are considered. Local precipitation and temperature instrumental data and interview data from farmers were used. The instrumental data shows that the climate is getting warmer and drier, the latter despite large interannual variability. The trend is seen on the local and regional level. Farmers’ perception of climatic variability corresponds well with the data record. During the last 20 years, the farmers have become less dependent on agriculture by adopting a more diversified livelihood. This adaptation makes them less vulnerable to climate variability. It was found that government policies and reforms had a stronger influence on land use than climate variability. Small-scale farmers should therefore be considered as adaptive to changing situations, planned and non-consciously planned.
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| 5. |
- Knutsson, Per, 1978, et al.
(author)
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Correction of static and non-common path aberrations in an adaptive optics system using inherent calibration data
- 2021
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In: Optics Express. - : Optica Publishing Group. - 1094-4087. ; 29:3, s. 3406-3414
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Journal article (peer-reviewed)abstract
- For low-order adaptive optics systems, a method that is able to correct for system aberrations in the final focal plane is presented. The paper presents a novel figure of merit, corresponding to the integrated non-normalized tip-tilt-free optical transfer function. The inherent singular value decomposition modal content of the interaction matrix is used to optimize this figure of merit. The method has proven to be stable and robust, providing a simple mean to facilitate diffraction limited imaging in an experimental setup for ophthalmic applications. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
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| 6. |
- Popovic, Zoran, 1966, et al.
(author)
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Dual Conjugate Adaptive Optics Prototype for Wide Field High Resolution Retinal Imaging
- 2012
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In: Adaptive Optics Progress. - Rijeka : Intech. - 9789535108948 ; , s. 3-21
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Book chapter (other academic/artistic)abstract
- Retinal imaging is limited due to optical aberrations caused by imperfections in the optical media of the eye. Consequently, diffraction limited retinal imaging can be achieved if optical aberrations in the eye are measured and corrected. Information about retinal pathology and structure on a cellular level is thus not available in a clinical setting but only from histological studies of excised retinal tissue. In addition to limitations such as tissue shrinkage and distortion, the main limitation of histological preparations is that longitudinal studies of disease progression and/or results of medical treatment are not possible. Adaptive optics (AO) is the science, technology and art of capturing diffraction-limited images in adverse circumstances that would normally lead to strongly degraded image quality and loss of resolution. In non-military applications, it was first proposed and implemented in astronomy. AO technology has since been applied in many disciplines, including vision science, where retinal features down to a few microns can be resolved by correcting the aberrations of ocular optics. As the focus of this chapter is on AO retinal imaging, we will focus our description to this particular field.
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| 7. |
- Popovic, Zoran, 1966, et al.
(author)
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Noninvasive imaging of human foveal capillary network using dual-conjugate adaptive optics.
- 2011
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In: Investigative ophthalmology & visual science. - : Association for Research in Vision and Ophthalmology (ARVO). - 1552-5783. ; 52:5, s. 2649-55
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Journal article (peer-reviewed)abstract
- PURPOSE: To demonstrate noninvasive imaging of human foveal capillary networks with a high-resolution, wide-field, dual-conjugate adaptive optics (DCAO) imaging instrument. METHODS: The foveal capillary networks of five healthy subjects with no previous history of ocular or neurologic disease or surgery were imaged with a novel high-resolution, wide-field DCAO instrument. The foveal avascular zone (FAZ) in each image was defined using a manual procedure. An automated algorithm based on publicly available and custom-written software was used to identify vessels and extract morphologic FAZ and vessel parameters. Capillary densities were calculated in two annular regions of interest (ROIs) outside the FAZ (500 μm and 750 μm outer radius from the foveal center) and in the superior, inferior, temporal, and nasal quadrants within the two ROIs. RESULTS: Mean FAZ area was 0.302 ± 0.100 mm(2), and mean capillary density (length/area) in the inner ROI was 38.0 ± 4.0 mm(-1) and 36.4 ± 4.0 mm(-1) in the outer ROI. The difference in ROI capillary density was not significant. There was no significant difference in quadrant capillary density within the two ROIs or between quadrants irrespective of ROI. CONCLUSIONS: The authors have demonstrated a technique for noninvasive imaging and semiautomated detection and analysis of foveal capillaries. In comparison with other studies, their method yielded lower capillary densities than histology but similar results to the current clinical gold standard, fluorescein angiography. The increased field of view of the DCAO instrument opens up new possibilities for high-resolution noninvasive clinical imaging of foveal capillaries.
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| 8. |
- Thaung, Jörgen, 1965, et al.
(author)
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Dual-conjugate adaptive optics for wide-field high-resolution retinal imaging.
- 2009
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In: Optics express. - 1094-4087. ; 17:6, s. 4454-67
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Journal article (peer-reviewed)abstract
- We present analysis and preliminary laboratory testing of a real-time dual-conjugate adaptive optics (DCAO) instrument for ophthalmology that will enable wide-field high resolution imaging of the retina in vivo. The setup comprises five retinal guide stars (GS) and two deformable mirrors (DM), one conjugate to the pupil and one conjugate to a plane close to the retina. The DCAO instrument has a closed-loop wavefront sensing wavelength of 834 nm and an imaging wavelength of 575 nm. It incorporates an array of collimator lenses to spatially filter the light from all guide stars using one adjustable iris, and images the Hartmann patterns of multiple reference sources on a single detector. Zemax simulations were performed at 834 nm and 575 nm with the Navarro 99 and the Liou- Brennan eye models. Two correction alternatives were evaluated; conventional single conjugate AO (SCAO, using one GS and a pupil DM) and DCAO (using multiple GS and two DM). Zemax simulations at 575 nm based on the Navarro 99 eye model show that the diameter of the corrected field of view for diffraction-limited imaging (Strehl >or= 0.8) increases from 1.5 deg with SCAO to 6.5 deg using DCAO. The increase for the less stringent condition of a wavefront error of 1 rad or less (Strehl >or= 0.37) is from 3 deg with SCAO to approximately 7.4 deg using DCAO. Corresponding results for the Liou-Brennan eye model are 3.1 deg (SCAO) and 8.2 deg (DCAO) for Strehl >or= 0.8, and 4.8 deg (SCAO) and 9.6 deg (DCAO) for Strehl >or= 0.37. Potential gain in corrected field of view with DCAO is confirmed both by laboratory experiments on a model eye and by preliminary in vivo imaging of a human eye.
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