| 1. |
- Beal, Jacob, et al.
(author)
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Robust estimation of bacterial cell count from optical density
- 2020
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In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Journal article (peer-reviewed)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Chee, Pei Nen Esther, et al.
(author)
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Determinants of intention-to-use first-/last-mile automated bus service
- 2020
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In: Transportation Research Part A. - : Elsevier. - 0965-8564 .- 1879-2375. ; 139, s. 350-375
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Journal article (peer-reviewed)abstract
- The successful adoption of a product or service by its target market or users relies on delivering a product or service in line with their needs and expectations. Failure to do so will likely result in a low rate of uptake or use of the product or service. This study sought to identify the criteria by which potential users of a first-/last-mile automated bus (AB) service would evaluate the service, and accordingly decide whether to use or disregard the service. This research investigated var-ious explanatory factors affecting users' perceptions of the service's quality and utility, and which enhanced or diminished their intentions to use it. The data analysed in this study was collected from a survey conducted in February and March of 2018 in Stockholm, Sweden, during a trial operation of a first-/last-mile AB service. Three-factor theory analysis, commonly used to analyse services, was applied to this data in order to identify users' core perceptions about the service, which in turn influence their intention-to-use the service. Structural equation modelling was used to identify the significant factors that influence the identified perceptions influencing the in-tention-to-use the service. This study found that different subgroups of users prioritised different attributes. Prospective users (with no prior experience with the service) were most concerned with the frequency of service. Their intention-to-use the service greatly increased when the service frequency is comparable to the service frequency of a regular public bus service. Experienced users' intentions to continue using the service greatly increased when the buses were made more comfortable. This study additionally found that users' perceptions of the service's quality were also influenced by numerous factors including the passenger's age, income level, preferred mode of travel for daily trips, preferred mode of travel for first-/last-mile trips, being tech-savvy or not, and their level of familiarity with automated driving technology.
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| 3. |
- Chee, Pei Nen Esther, et al.
(author)
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Longitudinal interactions between experienced users' service valuations and willingness-to-use a first-/last-mile automated bus service
- 2021
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In: Travel Behaviour & Society. - : Elsevier BV. - 2214-367X .- 2214-3688. ; 22, s. 252-261
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Journal article (peer-reviewed)abstract
- Successful implementation of a first-/last-mile automated bus (AB) service depends on consumers' actual adoption of the service. Consumers, when decided to take an AB ride for the first time, shall rely on their expectation of the service and capabilities of the technology. After the first ride of the vehicle, their value assessments of the service are further refined based on their actual ride experiences. Whether the operators can retain the users highly depend on such assessment. Thus, it is immensely important, when investigating users' adoption behaviour of a first-/last-mile AB service, we take into account the longitudinal changes of the users' valuation of the service. This is the research gap that this study is contributing. During a first-/last-mile AB service trial in Stockholm, Sweden, a panel data involving 185 respondents was available for analysis. The first survey was shortly after the launch of the trialled AB service and the second one was four months later. Structural Equation Modelling was used to investigate the changes of users' judging criteria across different socio-demographic groups, due to initial usage and the subsequent usage. The results show that the concerns affecting the users to continue with the service change with an increase in the ride experience. Willingness-to-use of the experienced users was initially affected by their level of appreciation with the safety and travel time with the service. However, ride comfort became a dominant factor with increasing ride experiences.
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| 4. |
- Chee, Pei Nen Esther, 1989-
(author)
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Understanding Changes in Decision-making Processes to Adopt First-/Last-Mile Automated Bus Service
- 2021
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Doctoral thesis (other academic/artistic)abstract
- This research investigates the changes in the interactions of objective factors (factors which are independent of perception e.g. socio-demographic characteristics), subjective factors (psychological factors which are inherent in individual), and user’s behavioural responses towards a new technology/service in response to actual experience with the technology/service. In specific, this research investigates the changes in decision-making parameters to adopt first-/last-mile automated bus service over three important adoption stages, as specified in diffusion of innovations theory: 1. decision (before any actual ride experiences), 2. implementation (first trial) and 3. continuation (after the first trial). Findings show that objective factors have both direct and indirect influences on users’ behavioural responses towards a new technology. There are dominant perceptions towards the technology among the same group of people with the same socio-demographic characteristics/travel characteristics/familiarity with the technology. However, the relationships between the objective factors with the associated perceptions are not stable when the users have gathered incomplete information about the technology. Decision made without complete information about the technology is subjected to logical fallacy. Consequently, the decision made is irrational and subject to changes after an individual gains complete information about the new technology/service through actual experience with the new technology/service. Actual ride experiences provide users complete information about the technology. As compared to the behavioural responses of first-time users, the behavioural responses of the adopters (users who continued with the service after the first trial) are stable and consistent. Also, reinforcement learning process was found to exist in the adopters of the first-/last mile automated bus service. The findings give strong evidence that users’ level of information about a new technology/service has a significant impact on the stability of the representation of both the objective and subjective factors. In conclusion, users’ level of information about a new technology/service has a crucial impact on the reliability of the representation of the objective factors and subjective factors identified from the travel behaviour studies of new technology/service like automated vehicle/bus. The decision made when users have incomplete information about a new technology is irrational and subject to changes. Hence, the representation of the objective factors and subjective factors identified from hypothetical studies in which the respondents lack real experience with automated vehicle/bus technology is unreliable. On the other hand, actual experience provides users with complete information about the new technology/service and allows users to learn about the technology/service. As a result, users can make a more rational decision hence the representation of the identified objective factors and subjective factors is reliable. As another contribution of this research, a systematic approach to obtain objective measurements from real-world pedestrian-automated bus interactions using LiDAR data is also demonstrated in this thesis. The approach developed can be used as the fundamental framework to measure the safety risk between a crossing pedestrian with an automated vehicle/bus. Also, the developed method is helpful to the designing of control algorithm of an automated bus due to the attainments of the actual pedestrians’ risk thresholds when they interact with an automated bus in the real-world setting.
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| 5. |
- Chee, Pei Nen Esther, et al.
(author)
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Which factors affect willingness-to-pay for automated vehicle services? : Evidence from public road deployment in Stockholm, Sweden
- 2020
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In: European Transport Research Review. - : SPRINGER. - 1867-0717 .- 1866-8887. ; 12:1
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Journal article (peer-reviewed)abstract
- Introduction Travel demand and travel satisfaction of a transport service are affected by user perceptions of the service quality attributes, and such perceptions should be included in studying user willingness-to-pay (WTP) for automated vehicle (AV) services. This study applied structural equation modelling with service quality attribute perceptions as latent variables affecting WTP. Objectives We investigated how WTP AV services are affected by socio-demographic characteristics, knowledge and experiences with AV, existing travel modes and particularly, perceptions of the associated service quality attributes. The AV services are: 1) on-demand personalised AV (PAV) service, 2) demand responsive shared AV (SAV) service, and 3) first-/last-mile automated bus (AB) service. Methods The data were collected from 584 potential users of a first-/last-mile AB service trial operated in Kista, Stockholm. Results Results show people hold different expectations towards each type of AV service. These expectations act as the minimum requirements for people to pay for the AV services. Respondents are found to be willing to pay more for PAV service if it is safe, provides good ride comfort, and is competitively priced relative to the price travelling by metro and train over a same distance. Other than service quality attribute perceptions, income level, existing travel modes for daily trips, familiarity with automated driving technology and AB ride experience are important factors affecting WTP for the AV services. Conclusion The developed model can be applied to understand expectations of potential users towards a new AV service, and to identify user groups who are willing to pay the service. New AV services can thus be designed sensibly according to users' actual needs.
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| 6. |
- Koh, Niak Sian, 1991-
(author)
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Safeguarding nature and people : Integrating economics, politics, and human rights to transform biodiversity policies and governance
- 2022
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Doctoral thesis (other academic/artistic)abstract
- None of the world’s biodiversity goals from the last decade were fully met, as biodiversity losses are occurring at an unprecedented rate. Policies are not always effective; their use may have adverse effects on people and nature. Biodiversity offsets are an example of a policy that can be used to protect and restore biodiversity loss from economic development. Yet, offsets have been criticized for poor ecological outcomes, commodifying nature, and creating social inequality. To address this challenge, we need to learn from the shortcomings of biodiversity policies and governance as new goals are being drafted under the Post-2020 Global Biodiversity Framework.This thesis examines how biodiversity policies can be designed and implemented for effective and equitable outcomes for people and biodiversity. I focus on the design (Paper I) and implementation (Paper II) by examining economic instruments in conservation. I then broaden to the governance landscape by analysing the implementation of policies in national (Paper III) and international regulatory contexts (Paper IV).The 4 papers cover a diversity of cases across the globe at different governance levels. Paper I conducted a policy analysis of offsets from six countries (Australia, England, Germany, Madagascar, South Africa, and the US), through an economic framing of biodiversity trading and institutional arrangements. Paper II reviewed market instruments for conservation, ecotourism and sport hunting in eastern and southern Africa, to analyse whether these instruments can be compatible with new ideas for conservation such as conviviality. Paper III investigated the politics around Mekong hydropower development, through multi-stakeholder interviews and a discourse analysis of the social and environmental impacts of a dam in Laos. Paper IV examined the implementation of the Convention on Biological Diversity (CBD) and how review mechanisms of human rights law can improve compliance.This thesis highlights that a human rights-based approach provides important conceptual and political support for biodiversity governance. It contributes to the science-policy interface with these insights. First, the institutional design and implementation are as important for the outcomes as the type of policy. In economic policies such as offsets, a high involvement of the market does not influence the level of commensurability, but increases the degree of commodification. Second, the contextual factors (politics and power relations) of policies should be acknowledged to address inequality. An institutional design and implementation that ensures meaningful participation and a balance of power is crucial for effective and equitable outcomes. Review mechanisms used in human rights help to navigate power inequities, by ensuring that all rights-holders have a substantial voice.Third, offsets can be designed with different institutional arrangements (state, market, voluntary). If a market approach is chosen with biodiversity trading, effective monitoring and regulation is needed to safeguard biodiversity. Lastly, to foster compliance with policies, management and enforcement approaches can be used in a complementary manner through positive incentives, sunshine methods, and negative incentives. Overall, this thesis provides insights of how to meet our global goals for protecting and restoring biodiversity, while safeguarding people and nature.
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