| 1. |
- Kehoe, Laura, et al.
(author)
-
Make EU trade with Brazil sustainable
- 2019
-
In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Journal article (other academic/artistic)
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| 2. |
- Andersson, Erik, et al.
(author)
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Stewardship in Urban Landscapes
- 2017
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In: The Science and Practice of Landscape Stewardship. - : Cambridge University Press. - 9781316499016 ; , s. 219-221
-
Book chapter (peer-reviewed)
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| 3. |
- Berg, Ulrika, et al.
(author)
-
Lack of sex differences in the IGF-IGFBP response to ultra endurance exercise.
- 2008
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In: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 18:6, s. 706-714
-
Journal article (peer-reviewed)abstract
- The insulin-like growth factor (IGF)-IGF binding proteins (BP) and the pituitary-gonadal axes were investigated during ultra endurance exercise in 16 endurance-trained athletes (seven women). Median duration of the race was 6.3 days. Although food and drink were ad libitum, energy balance was negative. Blood samples were drawn before (PRE), at the end of (END) and 24 h after (POST24h) the race. Serum concentrations of total IGF-I (t-IGF-I) and free IGF-I (f-IGF-I) decreased by 33 (SD 38)% and 54 (19)%, respectively. The decrease in t-IGF-I appeared to be associated to the total energy deficit during the race. At END, the IGFBP-3 fragmentation and IGFBP-1 were increased but these changes did not predict changes in f-IGF-I. An increase in POST24h IGFBP-2 levels in women was the only sex difference. Testosterone was decreased by 67 (12)% in the men and estradiol became undetectable in the women without any detectable increase in LH and/or FSH. In conclusion ultra endurance exercise results in similar IGF-IGFBP responses in men and women reflecting a catabolic state. IGFBP-2 was the only exception, with increased levels in women after exercise. A concomitant decrease in gonadal hormones was not related to endocrine changes in the IGF-IGFBP axis but may be related to local changes in IGF-I expression.
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| 4. |
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| 5. |
- Enqvist, Johan, 1982-, et al.
(author)
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Against the current : rewiring rigidity trap dynamics in urban water governance through civic engagement
- 2016
-
In: Sustainability Science. - : Springer Science and Business Media LLC. - 1862-4065 .- 1862-4057. ; 11:6, s. 919-933
-
Journal article (peer-reviewed)abstract
- This paper investigates how the agency of local residents can affect persistent and unsustainable practices in urban water supply governance. Using a case study from Bangalore, India, we analyze a social-ecological trap which developed after a shift to external water provision paired with rapid urbanization. The reluctance of forsaking initial investments in infrastructure and competence, and the subsequent loss of the local network of lakes built for harvesting rainwater, reinforced dependence on external sources while undermining groundwater levels in the city. These feedbacks made water scarcity a structurally persistent feature of Bangalore. This situation started to change when local residents recently started organizing to preserve and restore Bangalore's lakes. By entering collaborative management agreements with municipal authorities, these lake groups have restored and established effective protection of five lakes. Through a case study of this civic engagement we show that the lake restorations have the potential to counteract trap mechanisms by restoring ecological functions, and by reducing water scarcity as groundwater levels rise and authorities are relieved from maintenance and monitoring tasks. Importantly, these lake groups have also created opportunities for over a dozen similar groups to form across the city. This demonstrates that social movements can be an important source of change in social-ecological traps.
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| 6. |
- Enqvist, Johan, et al.
(author)
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Citizen networks in the Garden City : Protecting urban ecosystems in rapid urbanization
- 2014
-
In: Landscape and Urban Planning. - : Elsevier BV. - 0169-2046 .- 1872-6062. ; 130, s. 24-35
-
Journal article (peer-reviewed)abstract
- Citizen groups can be important actors in urban environmental stewardship, and network structure often influences function and performance. However, most previous studies focus on cities in developed countries, thereby overlooking conditions relevant for the parts of the planet where most people live and most urban growth is expected. This paper describes a citizen network engaged in environmental issues in Bangalore, India, where rapid urbanization puts pressure on conventional management structures as well as the ecosystems providing benefits for the city's inhabitants. The study uses a mixed methods approach of qualitative interviews and social network analysis. Results show that the citizen network functions as a platform that enables interaction between diverse interest groups, and as a watchdog that monitors parks, lakes and trees to prevent further loss of fragmented urban ecosystems. The network's activities are influenced by internal tensions between inclusiveness and efficiency, and between internal and external legitimacy. Although core actors have central network positions, strong leadership or political alliances are not considered important; members instead prefer to emphasize transparency and democratic participation. This limits the capacity to act collectively on controversial issues, but creates an inclusive forum that bridges between groups in the heterogeneous and dynamic population. This is important for monitoring Bangalore's fragmented ecosystems and for raising public awareness and support. Findings indicate an urgent need to develop a comprehensive framework for urban environmental stewardship, to better describe potential roles of citizens in governance across diverse social, political and ecological conditions, and during different periods of urban change.
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| 7. |
- Enqvist, Johan, 1982-, et al.
(author)
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Enhancing social–ecological fit from the bottom up : Urban lake networks and grassroots innovators
-
Other publication (other academic/artistic)abstract
- Urban environmental governance is often hampered by social institutions being poorly aligned with fragmented ecosystems. Bottom-up approaches have been argued to address this problem of social-ecological fit, but there is a lack of empirical understanding of how local initiatives might emerge and spread in a way that enhances fit. We study a system of hydrologically interconnected lakes in Bengaluru, which public authorities have largely failed to protect resulting in many degraded lakes and undermined societal and ecological benefits that the system of lakes provides. Local residents have, largely in response to these failures, formed lake groups and convinced municipal actors to recognize them as partners that share management responsibilities for certain lakes. These initiatives have inspired others to follow suit and work with lakes elsewhere in the city, hence triggering the question whether local lake groups in this way contribute to a better social–ecological fit at a broader landscape scale. This study mixes quantitative social–ecological network analysis with interviews to analyze fit and describe the processes by which lake management can be shaped to match ecosystem structure. Results show that certain key lake groups – enabled by supportive municipal officers – have successfully innovated how lakes are managed, acknowledging their place in and dependence on the broader network of interconnected lakes. In the wake of this, a new generation of collaborative lake groups is emerging, where lakes are often managed more holistically by recognizing them to be part of the larger network of lakes. The analysis identifies key lake groups that are instrumental to shaping the spread of the bottom-up driven initiatives in ways that aligns with the interconnected nature of the lake system. This is a process that relies on acknowledgement and support from public authorities, but is primarily driven by local actors. By describing this process of innovation and diffusion, the study contributes important lessons on how to enhance fit between governance arrangements and the ecosystem on which cities depend.
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| 8. |
- Enqvist, Johan, et al.
(author)
-
Informality and water justice : community perspectives on water issues in Cape Town's low-income neighbourhoods
- 2022
-
In: International Journal of Water Resources Development. - : Informa UK Limited. - 0790-0627 .- 1360-0648. ; 38:1, s. 108-129
-
Journal article (peer-reviewed)abstract
- Cape Town's water injustices are entrenched by the mismatch between government interventions and the lived realities in many informal settlements and other low-income areas. This transdisciplinary study draws on over 300 stories from such communities, showing overwhelming frustration with the municipality's inability to address leaking pipes, faulty bills and poor sanitation. Cape Town's interventions typically rely on technical solutions that tend to ignore or even exacerbate the complex social problems on the ground. Water justice requires attention be paid to the range of everyday realities that exist in the spectrum from formal to informal settlements.
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| 9. |
- Enqvist, Johan P., et al.
(author)
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Are bottom-up approaches good for promoting social-ecological fit in urban landscapes?
- 2020
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In: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 49:1, s. 49-61
-
Journal article (peer-reviewed)abstract
- Bottom-up approaches are often presented as a remedy to environmental governance problems caused by poorly aligned social institutions and fragmented ecosystems. However, there is a lack of empirical evidence demonstrating how such social-ecological fit might emerge and help achieve desirable outcomes. This paper combines quantitative social-ecological network analysis with interviews to investigate whether bottom-up approaches in lake governance improve the fit. We study groups of residents seeking to improve management of a network of lakes in Bengaluru, India. Results show that 23 'lake groups' collaborate in a way that aligns with how lakes are hydrologically connected, thus strengthening the social-ecological fit. Three groups founded around 2010 have mobilized support from municipal officers and introduced an ecosystem-based approach to lake management that recognizes their ecological functions and dependence on, the broader hydrological network. These groups have also changed how other lake groups operate: groups founded after 2010 are more collaborative and more prone to contribute to social-ecological fit compared to the older lake groups. This paper demonstrates the utility of a theoretically informed method for examining the impact of bottom-up approaches, which, we argue, is important for a more informed perspective on their relevance and potential contribution to urban environmental governance.
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| 10. |
- Enqvist, Johan Pecanha, et al.
(author)
-
Stewardship as a boundary object for sustainability research : Linking care, knowledge and agency
- 2018
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In: Landscape and Urban Planning. - : Elsevier BV. - 0169-2046 .- 1872-6062. ; 179, s. 17-37
-
Research review (peer-reviewed)abstract
- Current sustainability challenges - including biodiversity loss, pollution and land-use change require new ways of understanding, acting in and caring for the landscapes we live in. The concept of stewardship is increasingly used in research, policy and practice to articulate and describe responses to these challenges. However, there are multiple meanings and framings of stewardship across this wide user base that reflect different disciplinary purposes, assumptions and expertise, as well as a long history of use in both academic and lay contexts. Stewardship may therefore be considered a 'boundary object'; that is, a conceptual tool that enables collaboration and dialogue between different actors whilst allowing for differences in use and perception. This paper seeks to map out the multiple meanings of stewardship in the literature and help researchers and practitioners to navigate the challenges and opportunities that come with using the term. We provide the first qualitative systematic review of stewardship, and identify four distinct meanings of the concept in the literature: Ethic, Motivation, Action and Outcome. We then develop a novel framework for thinking through and connecting these multiple meanings, centered around three dimensions: care, knowledge and agency. This framework is used to identify the care dimension and relational approaches as important areas for future stewardship research. In these efforts - and for scholars engaging with the stewardship concept more broadly - this paper can act as a helpful 'centering device', connecting practitioners, policy-makers and researchers from multiple disciplines in pursuit of sustainability.
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| 11. |
- Enqvist, Johan, 1982-, et al.
(author)
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Pathways to urban environmental stewardship : Sense of place and civic engagement for urban waterfronts
-
Other publication (other academic/artistic)abstract
- Participation of local residents is considered beneficial for urban environmental stewardship, but the understanding of how urban stewards relate to the places they work with is poorly developed. This study of civic groups working to steward urban waterfronts challenges the notion that stronger attachment drives deeper commitment to stewardship. The study looks at three types of groups doing stewardship work on waterfronts and water bodies in New York City: community groups, environmental groups and recreational groups. Using interviews and Likert scale surveys (n=31), we assessed stewardship activities, place attachment and place meanings that members associate with site that each group works with. Our findings show that community group members are more attached to the sites they work with than members of environmental or recreational groups, but environmental groups report the greatest effort put into stewardship work. Further, we show that place meanings reveal different categories of groups based on how they currently view the site (as a place of work, a place of home, or a place of use), and what they want to achieve for it in their stewardship work: some groups work to restore what the place was previously, others work to protect what it currently is, while a few work to create a new identity for their place. These findings demonstrate how pathways to stewardship differ and are not dependent on strong place attachment; however, they can generate fundamentally different outcomes depending on what place meanings stewardship seeks to protect.
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| 12. |
- Enqvist, Johan, 1982-
(author)
-
Stewardship in an urban world : Civic engagement and human–nature relations in the Anthropocene
- 2017
-
Doctoral thesis (other academic/artistic)abstract
- Never before have humans wielded a greater ability to alter and disrupt planetary processes. Our impact is becoming so noticeable that a new geological epoch has been proposed – the Anthropocene – in which Earth systems might no longer maintain the stable and predictable conditions of the past 12 millennia. This is particularly evident in the rapid expansion of urban areas, where a majority of humans now live and where environmental changes such as rising temperatures and habitat loss are happening faster than elsewhere. In light of this, questions have been raised about what a more responsible relationship between humans and the rest of the planet might look like. Scholars in sustainability science employ the concept of ‘stewardship’ in searching for an answer; however, with multiple different applications and definitions, there is a need to better understand what stewardship is or what novelty it might add to sustainability research. This thesis investigates stewardship empirically through two case studies of civic engagement for protecting nature in cities – Bengaluru, India and New York City, USA. Further, the thesis also proposes a conceptual framework for how to understand stewardship as a relation between humans and the rest of nature, based on three dimensions: care, knowledge and agency. This investigation into stewardship in the urban context uses a social–ecological systems approach to guide the use of mixed theory and methods from social and natural sciences. The thesis is organized in five papers. Paper I reviews defining challenges in managing urban social–ecological systems and proposes that these can more effectively be addressed by collaborative networks where public, civic, other actors contribute unique skills and abilities. Paper II and Paper III study water resource governance in Bengaluru, a city that has become dependent on external sources while its own water bodies become degraded and depleted.Paper II analyzes how locally based ‘lake groups’ are able to affect change through co-management arrangements, reversing decades of centralization and neglect of lakes’ role in Bengaluru’s water supply.Paper III uses social–ecological network analysis to analyze how patterns in lake groups’ engagements and collaborations show better fit with ecological connectivity of lakes.Paper IV employs sense of place methods to explore how personal bonds to a site shapes motivation and goals in waterfront stewardship in New York City. Finally,Paper V reviews literature on stewardship and proposes a conceptual framework to understand and relate different uses and underlying epistemological approaches in the field. In summary, this thesis presents an empirically grounded contribution to how stewardship can be understood as a human–nature relation emergent from a deep sense ofcare and responsibility, knowledge and learning about how to understand social–ecological dynamics, and theagency and skills needed to influence these dynamics in a way that benefits a greater community of humans as others. Here, the care dimension is particularly important as an underappreciated aspect of social–ecological relations, and asset for addressing spatial and temporal misalignment between management institutions and ecosystem. This thesis shows that care for nature does not erode just because green spaces are degraded by human activities – which may be crucial for promoting stewardship in the Anthropocene.
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| 13. |
- Enqvist, Johan, 1982-, et al.
(author)
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Sustainable water tariffs and inequality in post-drought Cape Town : exploring perceptions of fairness
- 2023
-
In: Sustainability Science. - : Springer Science and Business Media LLC. - 1862-4065 .- 1862-4057. ; 18:2, s. 891-905
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Journal article (peer-reviewed)abstract
- Fair allocation of diminishing natural resources is increasingly central to sustainability. This includes the allocation of costs related to providing access, such as dams, pipes and pumps delivering clean water. Water tariffs are often designed to both recover these costs, meet social needs of water services to the poor, and incentivise conservation in dry times. However, strained public finances, prolonged droughts and economic inequality can undermine these goals and force prioritisations that many see as unfair. This happened in Cape Town, South Africa, during its 2015–2018 water crisis. This study investigates what residents in three different socioeconomic contexts view as fair water tariffs 1 year after the crisis. Using Q method, we describe five distinct perspectives on fairness: ‘the Insurer’, ‘the Individualist’, ’the Bureaucrat’, ‘the Humanitarian’, and ‘the Prepper’. These, we argue, can help distinguish between different ideas of what fairness implies, and what is required to promote it. We exemplify this by examining how viewpoints might have been shaped by specific communities’ experiences during and after the apartheid state’s discriminatory segregation policies. Using distributive, procedural and interactional interpretations of fairness, we discuss how the complex layers of poverty, inequality, mistrust, privilege and discrimination might produce different experiences and ideas of who should pay for and benefit from water services. Using these insights, we also reflect on the merits of tariffs that emphasise cost recovery and resource conservation over social needs, and the risks this poses for growing informal settlements in climate-stressed cities of the global South.
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| 14. |
- Enqvist, Johan, 1982-
(author)
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Urban environmental stewardship : Roles and reasons for civic engagements in governance of social-ecological systems
- 2015
-
Licentiate thesis (other academic/artistic)abstract
- Stewardship as a concept is increasingly brought forward as a goal to reach sustainability goals of ensuring human wellbeing within the limits of Earth’s life support systems. Scholarship on the required capacities for planetary stewardship is growing rapidly, as are the insights. This thesis focuses on contributing with knowledge about what stewardship implies in terms of civic engagement in environmental issues, particularly in contexts where these can be particularly challenging: rapidly changing cities. Paper I describes the internal functioning of a citizen network engaged in various environmental issues in Bangalore, India. Analyzing social network structure and desired outcomes, it shows that while the loose structure inhibits efficiency, it encourages inclusiveness and builds legitimacy among members. Despite a reduced capacity to actively mobilize members, the network facilitates ecosystem monitoring and serves as an information platform to connect diverse groups across the city. Paper II describes how local engagement to restore Bangalorean lakes can influence city-level governance of water supply. Following key events in the 1960s, Bangalore has become increasingly dependent on a single source of water and seems unable to explore other supply approaches for its rapidly growing population. The study shows that the system’s trap-like dynamics can be rewired by citizen-based lake groups by incentivizing authorities to break long-standing centralization trends. By re- acknowledging the water bodies’ multifunctional role as man-made water harvesting units, groups have gathered local support and improved monitoring to protect lakes after restoration. Together, the two papers show that civic involvement in urban environmental stewardship can improve governance by complementing and acting as a watchdog over public authorities.
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| 15. |
- Enqvist, Martin, 1976-, et al.
(author)
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Detection of Unmodeled Nonlinearities Using Correlation Methods
- 2007
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In: Proceedings of the 2007 IEEE Instrumentation and Measurement Technology Conference. - 1424405882 ; , s. 1-6
-
Conference paper (peer-reviewed)abstract
- This paper concerns the validation of linear models with respect to unmodeled nonlinearities. Two versions of a method for nonlinearity detection based on estimators of higher order cross-correlations are described and evaluated. Unlike many existing approaches, the proposed method seems to be applicable to a wide range of systems and input signals. It can also distinguish between even and odd nonlinearities.
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| 16. |
- Enqvist, Monika, et al.
(author)
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Systemic and Intra-Nodal Activation of NK Cells After Rituximab Monotherapy for Follicular Lymphoma.
- 2019
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In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 10
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Journal article (peer-reviewed)abstract
- Monotherapy with the anti-CD20 monoclonal antibody rituximab can induce complete responses (CR) in patients with follicular lymphoma (FL). Resting FcRγIII+ (CD16+) natural killer (NK) cells respond strongly to rituximab-coated target cells in vitro. Yet, the contribution of NK cells in the therapeutic effect in vivo remains unknown. Here, we followed the NK cell repertoire dynamics in the lymph node and systemically during rituximab monotherapy in patients with FL. At baseline, NK cells in the tumor lymph node had a naïve phenotype albeit they were more differentiated than NK cells derived from control tonsils as determined by the frequency of CD56dim NK cells and the expression of killer cell immunoglobulin-like receptors (KIR), CD57 and CD16. Rituximab therapy induced a rapid drop in NK cell numbers coinciding with a relative increase in the frequency of Ki67+ NK cells both in the lymph node and peripheral blood. The Ki67+ NK cells had slightly increased expression of CD16, CD57 and higher levels of granzyme A and perforin. The in vivo activation of NK cells was paralleled by a temporary loss of in vitro functionality, primarily manifested as decreased IFNγ production in response to rituximab-coated targets. However, patients with pre-existing NKG2C+ adaptive NK cell subsets showed less Ki67 upregulation and were refractory to the loss of functionality. These data reveal variable imprints of rituximab monotherapy on the NK cell repertoire, which may depend on pre-existing repertoire diversity.
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| 17. |
- Enqvist, Per, et al.
(author)
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Minimal Itakura-Saito distance and Covariance interpolation
- 2008
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In: 47TH IEEE CONFERENCE ON DECISION AND CONTROL, 2008 (CDC 2008). - 9781424431243 ; , s. 137-142
-
Conference paper (peer-reviewed)abstract
- Identification of power spectral densities rely on measured second order statistics such as, e.g. covariance estimates. In the family of power spectra consistent with such an estimate a representative spectra is singled out; examples of such choices are the Maximum entropy spectrum and the Correlogram. Here, we choose a prior spectral density to represent a priori information, and the spectrum closest to the prior in the Itakura-Saito distance is selected. It is known that this can be seen as the limit case when the cross-entropy principle is applied to a gaussian process. This work provides a quantitative measure of how close a finite covariance sequence is to a spectral density in the Itakura-Saito distance. It is given by a convex optimization problem and by considering its dual the structure of the optimal spectrum is obtained. Furthermore, it is shown that strong duality holds and that a covariance matching coercive spectral density always exists. The methods presented here provides tools for discrimination between power spectrum, identification of power spectrum, and for incorporating given data in this process.
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| 18. |
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| 19. |
- Fejne, Frida, 1986, et al.
(author)
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Multiatlas Segmentation Using Robust Feature-Based Registration
- 2017
-
In: , Cloud-Based Benchmarking of Medical Image Analysis. - Cham : Springer International Publishing. - 9783319496429 ; , s. 203-218
-
Book chapter (other academic/artistic)abstract
- This paper presents a pipeline which uses a multiatlas approach for multiorgan segmentation in whole-body CT images. In order to obtain accurate registrations between the target and the atlas images, we develop an adapted feature-based method which uses organ-specific features. These features are learnt during an offline preprocessing step, and thus, the algorithm still benefits from the speed of feature-based registration methods. These feature sets are then used to obtain pairwise non-rigid transformations using RANSAC followed by a thin-plate spline refinement or NiftyReg. The fusion of the transferred atlas labels is performed using a random forest classifier, and finally, the segmentation is obtained using graph cuts with a Potts model as interaction term. Our pipeline was evaluated on 20 organs in 10 whole-body CT images at the VISCERAL Anatomy Challenge, in conjunction with the International Symposium on Biomedical Imaging, Brooklyn, New York, in April 2015. It performed best on majority of the organs, with respect to the Dice index.
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| 20. |
- Forslund, Elin, et al.
(author)
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Microchip-Based Single-Cell Imaging Reveals That CD56(dim) CD57(-)KIR(-)NKG2A(+) NK Cells Have More Dynamic Migration Associated with Increased Target Cell Conjugation and Probability of Killing Compared to CD56(dim)CD57(-)KIR(-)NKG2A(-) NK Cells
- 2015
-
In: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 195:7, s. 3374-3381
-
Journal article (peer-reviewed)abstract
- NK cells are functionally educated by self-MHC specific receptors, including the inhibitory killer cell Ig-like receptors (KIRs) and the lectin-like CD94/NKG2A heterodimer. Little is known about how NK cell education influences qualitative aspects of cytotoxicity such as migration behavior and efficacy of activation and killing at the single-cell level. In this study, we have compared the behavior of FACS-sorted CD56(dim)CD57(-)KIR(-)NKG2A(+) (NKG2A(+)) and CD56(dim)CD57(-)KIR(-)NKG2A(+) (lacking inhibitory receptors; IR-) human NK cells by quantifying migration, cytotoxicity, and contact dynamics using microchip-based live cell imaging. NKG2A(+) NK cells displayed a more dynamic migration behavior and made more contacts with target cells than IR-NK cells. NKG2A(+) NK cells also more frequently killed the target cells once a conjugate had been formed. NK cells with serial killing capacity were primarily found among NKG2A(+) NK cells. Conjugates involving IR- NK cells were generally more short-lived and IR- NK cells did not become activated to the same extent as NKG2A(+) NK cells when in contact with target cells, as evident by their reduced spreading response. In contrast, NKG2A(+) and IR- NK cells showed similar dynamics in terms of duration of conjugation periods and NK cell spreading response in conjugates that led to killing. Taken together, these observations suggest that the high killing capacity of NKG2A(+) NK cells is linked to processes regulating events in the recognition phase of NK-target cell contact rather than events after cytotoxicity has been triggered.
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| 21. |
- Fredriksson, Johan, et al.
(author)
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Efficient algorithms for robust estimation of relative translation
- 2016
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In: Image and Vision Computing. - : Elsevier BV. - 0262-8856. ; 52, s. 114-124
-
Journal article (peer-reviewed)abstract
- One of the key challenges for structure from motion systems in order to make them robust to failure is the ability to handle outliers among the correspondences. In this paper we present two new algorithms that find the optimal solution in the presence of outliers when the camera undergoes a pure translation. The first algorithm has polynomial-time computational complexity, independently of the amount of outliers. The second algorithm does not offer such a theoretical complexity guarantee, but we demonstrate that it is magnitudes faster in practice. No random sampling approaches such as RANSAC are guaranteed to find an optimal solution, while our two methods do. We evaluate and compare the algorithms both on synthetic and real experiments. We also embed the algorithms in a larger system, where we optimize for the rotation angle as well (the rotation axis is measured by other means). The experiments show that for problems with a large amount of outliers, the RANSAC estimates may deteriorate compared to our optimal methods.
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| 22. |
- Fredriksson, Johan, et al.
(author)
-
Fast and Reliable Two-View Translation Estimation
- 2014
-
In: Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition. - 1063-6919. - 9781479951178 ; , s. 1606-1612
-
Conference paper (peer-reviewed)abstract
- It has long been recognized that one of the fundamental difficulties in the estimation of two-view epipolar geometry is the capability of handling outliers. In this paper, we develop a fast and tractable algorithm that maximizes the number of inliers under the assumption of a purely translating camera. Compared to classical random sampling methods, our approach is guaranteed to compute the optimal solution of a cost function based on reprojection errors and it has better time complexity. The performance is in fact independent of the inlier/outlier ratio of the data. This opens up for a more reliable approach to robust ego-motion estimation. Our basic translation estimator can be embedded into a system that computes the full camera rotation. We demonstrate the applicability in several difficult settings with large amounts of outliers. It turns out to be particularly well-suited for small rotations and rotations around a known axis (which is the case for cellular phones where the gravitation axis can be measured). Experimental results show that compared to standard RANSAC methods based on minimal solvers, our algorithm produces more accurate estimates in the presence of large outlier ratios.
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| 23. |
- Humphreys, Kristina, et al.
(author)
-
Voicing resilience through subjective well-being : community perspectives on responding to water stressors and COVID-19
- 2022
-
In: Ecology and Society. - : Resilience Alliance, Inc.. - 1708-3087. ; 27:2
-
Journal article (peer-reviewed)abstract
- Interactions among social inequalities, environmental stressors, and shocks are illustrated through communities??? subjective experiences of water-related challenges and responses to crises. This situation is perhaps most visible in the COVID-19 pandemic???s impact on marginalized communities where climate change and systemic inequities are already threatening access to water and sanitation. It is critical to integrate dimensions related to well-being into research about vulnerable communities??? capacities and strategies for coping and adapting to such crises. Here, we investigate water-related risks to health and well-being using a subjectivity lens, a particularly useful tool for understanding community-level resilience to lesser-known stressors and crisis impacts. To inform this study, we used households??? self-reported water issues in Cape Town, South Africa???s low-income areas from before the pandemic, in addition to community responses during the pandemic. The findings show how inadequate access to water and sanitation affects people???s health and well-being, both directly by exposure to wastewater and impaired hygiene, and indirectly by creating stress and social conflict, and undermining subsistence gardening and medical self-care. However, our study also illustrates how grassroots-led responses to the COVID-19 crisis address these vulnerabilities and identify priorities for managing water to support well-being. The results demonstrate two ways that subjective perceptions of well-being can help to promote resilience: first, by identifying stressors that undermine community well-being and adaptive capacity; and second, by voicing community experiences that can help to guide crisis responses and initiatives critical for adapting to social-ecological shocks. The results have important implications for enabling transformative change that aligns efforts to address issues linked to poverty and inequality with those seeking to respond to environmental emergencies.
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| 24. |
- Kahl, Fredrik, 1972, et al.
(author)
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Good Features for Reliable Registration in Multi-Atlas Segmentation
- 2015
-
In: CEUR Workshop Proceedings. - 1613-0073. ; 1390:January, s. 12-17
-
Conference paper (peer-reviewed)abstract
- This work presents a method for multi-organ segmentation in whole-body CT images based on a multi-atlas approach. A robust and efficient feature-based registration technique is developed which uses sparse organ specific features that are learnt based on their ability to register different organ types accurately. The best fitted feature points are used in RANSAC to estimate an affine transformation, followed by a thin plate spline refinement. This yields an accurate and reliable nonrigid transformation for each organ, which is independent of initialization and hence does not suffer from the local minima problem. Further, this is accomplished at a fraction of the time required by intensity-based methods. The technique is embedded into a standard multi-atlas framework using label transfer and fusion, followed by a random forest classifier which produces the data term for the final graph cut segmentation. For a majority of the classes our approach outperforms the competitors at the VISCERAL Anatomy Grand Challenge on segmentation at ISBI 2015.
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| 25. |
- Karlsson, Johan, et al.
(author)
-
Confidence assessment for spectral estimation based on estimated covariances
- 2016
-
In: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781479999880 ; , s. 4343-4347
-
Conference paper (peer-reviewed)abstract
- In probability theory, time series analysis, and signal processing, many identification and estimation methods rely on covariance estimates as an intermediate statistics. Errors in estimated covariances propagate and degrade the quality of the estimation result. In particular, in large network systems where each system node of the network gather and pass on results, it is important to know the reliability of the information so that informed decisions can be made. In this work, we design confidence regions based on covariance estimates and study how these can be used for spectral estimation. In particular, we consider three different confidence regions based on sets of unitarily invariant matrices and bound the eigenvalue distribution based on three principles: uniform bounds; arithmetic and harmonic means; and the Marcenko-Pastur Law eigenvalue distribution for random matrices. Using these methodologies we robustly bound the energy in a selected frequency band, and compare the resulting spectral bound from the respective confidence regions.
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