| 1. |
- Stevens, R., et al.
(författare)
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Microstructured photonic crystal for single-mode long wavelength VCSELs
- 2008
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Ingår i: Semiconductor Lasers and Laser Dynamics III. - : SPIE.
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Konferensbidrag (refereegranskat)abstract
- In this article, we report on long wavelength (1.27 ÎŒm) single-mode micro-structured photonic crystal strained InGaAs quantum wells VCSELs for optical interconnection applications. Single fundamental mode room-temperature continuous-wave lasing operation was demonstrated for devices designed and processed with different two-dimensional etched patterns. The conventional epitaxial structure was grown by Metal-Organic Vapor Phase Epitaxy (MOVPE) and contains fully doped GaAs/AlGaAs DBRs, one oxidation layer and three strained InGaAs quantum wells. The holes were etched half-way through the top-mirror following various designs (triangular and square lattices) and with varying hole's diameters and pitches. We obtained up to 1.7 mW optical output power and more than 30 dB Side-Mode Suppression Ratio (SMSR) at room temperature and in continuous wave operation. Systematic static electrical, optical and spectral characterization was performed on wafer using an automated probe station. Numerical modeling using the MIT Photonic-Bands (MPB [1]) package of the transverse modal behaviors in the photonic crystal was performed using the plane wave method in order to understand the index-guiding effects of the chosen patterns, and to further optimize the design structures for mode selection at the given wavelength.
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| 2. |
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| 3. |
- Hegger, Dries, et al.
(författare)
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Toward more flood resilience : Is a diversification of flood risk management strategies the way forward?
- 2016
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Ingår i: Ecology and Society. - 1708-3087. ; 21:4
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Tidskriftsartikel (refereegranskat)abstract
- European countries face increasing flood risks because of urbanization, increase of exposure and damage potential, and the effects of climate change. In literature and in practice, it is argued that a diversification of strategies for flood risk management (FRM), including flood risk prevention (through proactive spatial planning), flood defense, flood risk mitigation, flood preparation, and flood recovery, makes countries more flood resilient. Although this thesis is plausible, it should still be empirically scrutinized. We aim to do this. Drawing on existing literature we operationalize the notion of “flood resilience” into three capacities: capacity to resist; capacity to absorb and recover; and capacity to transform and adapt. Based on findings from the EU FP7 project STAR-FLOOD, we explore the degree of diversification of FRM strategies and related flood risk governance arrangements at the national level in Belgium, England, France, the Netherlands, Poland, and Sweden, as well as these countries’ achievement in terms of the three capacities. We found that the Netherlands and to a lesser extent Belgium have a strong capacity to resist, France a strong capacity to absorb and recover, and especially England a high capacity to transform and adapt. Having a diverse portfolio of FRM strategies in place may be conducive to high achievements related to the capacities to absorb/recover and to transform and adapt. Hence, we conclude that diversification of FRM strategies contributes to resilience. However, the diversification thesis should be nuanced in the sense that there are different ways to be resilient. First, the three capacities imply different rationales and normative starting points for flood risk governance, the choice between which is inherently political. Second, we found trade-offs between the three capacities, e.g., being resistant seems to lower the possibility to be absorbent. Third, to explain countries’ achievements in terms of resilience, the strategies’ feasibility in specific physical circumstances and their fit in existing institutional contexts (appropriateness), as well as the establishment of links between strategies, through bridging mechanisms, have also been shown to be crucial factors. We provide much needed reflection on the implications of this diagnosis for governments, private parties, and citizens who want to increase flood resilience
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| 4. |
- Pacureanu, Alexandra, et al.
(författare)
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Adaptive filtering for enhancement of the osteocyte cell network in 3D microtomography images
- 2013
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Ingår i: IRBM. - : Elsevier BV. - 1959-0318. ; 34:1-SI, s. 48-52
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Tidskriftsartikel (refereegranskat)abstract
- The osteocyte cell network in bone tissue is thought to orchestrate tissue adaptation and remodeling, thus holding responsibility for tissue quality. Previously, this structure has been studied mainly in 2D and its architecture and functions are not fully elucidated. The assessment of the osteocyte system is prerequisite for deeper understanding of bone remodeling and for advances in management of bone diseases. Our goal is to enable 3D isotropic imaging of bone at cellular level and to develop algorithms for quantitative image analysis of the cell network. We recently demonstrated accurate 3D imaging of this cell structure with synchrotron radiation tomography at submicrometric scale. Due to the limited spatial resolution of the imaging system and the constraints in terms of radiation dose, the images suffer from low signal to noise ratio and the detection of the cell dendrites is challenging. Here we detail a method for enhancement of the osteocyte network in human bone from 3D microtomography images. The approach combines Hessian-based 3D line enhancement and bilateral filtering. Our method enables extraction of the interconnected cells from noisy images, preserving the integrity of the cells and of their slender dendrites. Qualitative and quantitative results are presented.
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| 5. |
- Wahlgren, Nils, et al.
(författare)
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Multivariable Analysis of Outcome Predictors and Adjustment of Main Outcome Results to Baseline Data Profile in Randomized Controlled Trials Safe Implementation of Thrombolysis in Stroke-MOnitoring STudy (SITS-MOST)
- 2008
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Ingår i: Stroke. - 0039-2499 .- 1524-4628. ; 39:12, s. 3316-3322
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Tidskriftsartikel (refereegranskat)abstract
- Background and Purpose-The Safe Implementation of Thrombolysis in Stroke-MOnitoring STudy (SITS-MOST) unadjusted results demonstrated that intravenous alteplase is well tolerated and that the effects were comparable with those seen in randomized, controlled trials (RCTs) when used in routine clinical practice within 3 hours of ischemic stroke onset. We aimed to identify outcome predictors and adjust the outcomes of the SITS-MOST to the baseline characteristics of RCTs.Methods-The study population was SITS-MOST (n=6483) and pooled RCTs (n=464) patients treated with intravenous alteplase within 3 hours of stroke onset. Multivariable, backward stepwise regression analyses (until P <= 0.10) were performed to identify the outcome predictors for SITS-MOST. Variables appearing either in the final multivariable model or differing (P < 0.10) between SITS-MOST and RCTs were included in the prediction model for the adjustment of outcomes.Main outcome measures were symptomatic intracerebral hemorrhage, defined as National Institutes of Health Stroke Scale deterioration >= 1 within 7 days with any hemorrhage (RCT definition), mortality, and independency as defined by modified Rankin Score of 0 to 2 at 3 months.Results-The adjusted proportion of symptomatic intracerebral hemorrhage for SITS-MOST was 8.5% (95% CI, 7.9 to 9.0) versus 8.6% (6.3 to 11.6) for pooled RCTs; mortality was 15.5% (14.7 to 16.2) versus 17.3% (14.1 to 21.1); and independency was 50.4% (49.6 to 51.2) versus 50.1% (44.5 to 54.7), respectively. In the multivariable analysis, older age, high blood glucose, high National Institutes of Health Stroke Scale score, and current infarction on imaging scans were related to poor outcome in all parameters. Systolic blood pressure, atrial fibrillation, and weight were additional predictors of symptomatic intracerebral hemorrhage. Current smokers had a lower rate of symptomatic intracerebral hemorrhage. Disability before current stroke (modified Rankin Score 2 to 5), diastolic blood pressure, antiplatelet other than aspirin, congestive heart failure, patients treated in new centers, and male sex were related to high mortality at 3 months.Conclusions-The adjusted outcomes from SITS-MOST were almost identical to those in relevant RCTs and reinforce the conclusion drawn previously in the unadjusted analysis. We identified several important outcome predictors to better identify patients suitable for thrombolysis.
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