| 1. |
- Back, Jon, 1977-
(author)
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Designing Activity and Creating Experience : On People’s Play in Public places
- 2013
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Licentiate thesis (other academic/artistic)abstract
- This thesis deals with the design of play in public places; this can mean both pervasive games and other freer play activities. In these activities (as well as in many other game activities) the same game can spur many different ways to play it, and the same activity can be experienced differently by different players, and even differently on different occasions for the same player. An activity such as playing must be observed as a whole. The surrounding cul- ture, player preconceptions and the emergent mood within the group will affect the experience.By analysing previous frameworks, and using own design examples, a three level design framework is developed, functioning as a lens towards understanding the design of playful activities. The framework focuses on the player perspective, offering game design as an invitation and encouragement to engage in certain activities. The framework distinguishes between design at three levels:Designed construct (e.g. artefacts and rules)ActivityExperiencesBut it remains to be understood why people engage in the activities that lead to playful experiences. What encourages playful engagement? And why do people want to play one game, and not another?This question can be split into two parts:Engagement: starting to be interested in the activityCommitment: actually caring for the experienceThis issue is identified in the thesis, and examples show how convoluted this problem is, in particular in pervasive game settings. Challenges are pre- sented for future work.
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| 2. |
- Holmquist, Lars Erik, et al.
(author)
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Mobile Life: A Research Foundation for Mobile Services
- 2007. - 1
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In: Proceedings of the 6th Global Mobility Roundtable.
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Conference paper (peer-reviewed)abstract
- The telecom and IT industry is now facing the challenge of a second IT-revolution, where the spread of mobile and ubiquitous services will have an even more profound effect on commercial and social life than the recent Internet revolution. Users will expect services that are unique and fully adapted for the mobile setting, which means that the roles of the operators will change, new business models will be required, and new methods for developing and marketing services have to be found. Most of all, we need technology and services that put people at core. The industry must prepare to design services for a sustainable web of work, leisure and ubiquitous technology we can call the mobile life. In this paper, we describe the main components of a research agenda for mobile services, which is carried out at the Mobile Life Center at Stockholm University. This research program takes a sustainable approach to research and development of mobile and ubiquitous services, by combining a strong theoretical foundation (embodied interaction), a welldefined methodology (user-centered design) and an important domain with large societal importance and commercial potential (mobile life). Eventually the center will create an experimental mobile services ecosystem, which will serve as an open arena where partners from academia and industry can develop our vision an abundant future marketplace for future mobile servíces.
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| 3. |
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| 4. |
- Juhlin, Annika, et al.
(author)
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Staphylococcal biofilm gene expression on biomaterials - A methodological study
- 2017
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In: Journal of Biomedical Materials Research Part A. - : Wiley. - 1549-3296. ; 105:12, s. 3400-3412
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Journal article (peer-reviewed)abstract
- The combination of increased healthcare access, universal aging, and infallible therapy demands, synergistically drive the need for the development of biomaterial technologies that mitigate the challenge of biomaterial-associated infections (BAI). Staphylococcus epidermidis and Staphylococcus aureus account for the majority of BAI due to their ability to accumulate in adherent multilayered biofilm. This investigation details the development of gene expression assays to evaluate the genetic processes of attachment, accumulation, maturation, and dispersal phases of biofilms on biomaterials in vitro, while abiding by the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines. The biofilm formation of S. epidermidis on polyurethane (PU) central venous catheters and S. aureus on machined titanium (Ti) was examined in terms of gene expression at early and late time points. The results provided insight into how each stage of biofilm formation is orchestrated over time on these biomaterials in vitro. Furthermore, the results suggested that mechanical RNA extraction, organic solvents, elimination of genomic DNA, and preamplification are advisable strategies to implement for biofilm gene expression analysis. It is concluded that this method can be employed for the assessment of biofilm-biomaterial interactions at the molecular level. (c) 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3400-3412, 2017.
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| 5. |
- Juhlin, Magnus, 1975-, et al.
(author)
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Aerodynamic loads on buses due to crosswind gusts – On-road measurements
- 2008
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In: Vehicle System Dynamics. - : Taylor & Francis. - 0042-3114 .- 1744-5159. ; 46, s. 827-835
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Journal article (peer-reviewed)abstract
- Bus and coach traffic is considered to be one of the safest means of travelling. Still, there is a problem with accidents due to crosswind gusts. Therefore it is a need of improving the crosswind performance of buses. As a part of the work with improving the crosswind performance a method for estimating the aerodynamic loads on a bus when exposed to natural crosswind is proposed. The method is based on measurements of the vehicle response and the tire forces from which the aerodynamic loads are estimated using inverse simulations. The results are also shown to agree well with the results of other studies based on wind tunnel measurements. The estimated aerodynamic loads are intended to be used in a future study on crosswind sensitivity using a moving base simulator.
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| 6. |
- Juhlin, Magnus, 1975-
(author)
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Assessment of crosswind performance of buses
- 2009
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Doctoral thesis (other academic/artistic)abstract
- When driving a vehicle on the road, the driver has to compensate continuously for small directional deviations from the desired course due to disturbances such as crosswinds, road irregularities and unintended driver inputs. These types of deviations have a tiring effect on the driver and should therefore be minimised. When the magnitude of these disturbances increases, especially with crosswind, the directional deviation might become so large that the driver will have difficulties in compensating for it, and will thereby affect the traffic safety. The objective of this research work is to increase the understanding of the crosswind sensitivity of buses and to find solutions to the problem of improving the safety of buses with respect to crosswind performance. The work presented in this thesis contributes to increased knowledge about the directional stability of buses under the influence of crosswind gusts through parameter studies using detailed vehicle simulation models, through full-scale experiments and through studies of the effect of steering feel on the subjective and objective evaluation of crosswind performance. A natural crosswind gust model has been derived from wind tunnel measurements and implemented in a multi-body dynamics simulation tool. The aerodynamic loads of the crosswind gust model have been applied on a detailed vehicle model and the behaviour of the vehicle model has been studied for various vehicle configurations in both open- and closed-loop manoeuvres. The vehicle model, with parameters corresponding to real vehicle data, has been validated and the agreement with measurements is good. A method for estimating the aerodynamic loads on a bus due to crosswind on a road section is also presented. Aerodynamic loads under real conditions were estimated using this method and these data were thereafter used in a study where the effect of steering feel on the subjective and objective evaluation of crosswind performance was investigated using a moving-base driving simulator, with the aim of finding a relationship between steering feel and crosswind sensitivity. The thesis covers the influence of changing chassis-related parameters and aerodynamics-related parameters on the crosswind sensitivity, as well as the influence of the setting of the steering system on the crosswind performance of the driver-vehicle system. The results identify areas of high potential for improving the crosswind sensitivity of buses, such as the centre of gravity location and the yaw moment overshoot at gust entry. Furthermore, the study shows the importance of having a vehicle that facilitates prompt driver corrections for reducing the lateral deviation under crosswind excitation; i.e. it is shown that a steering system with the possibility of changing the yaw rate gradient referencing the steering-wheel input when the vehicle is subjected to a sudden crosswind has a good potential for improving the crosswind performance of the driver-vehicle system.
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| 7. |
- Juhlin, Magnus, 1975-, et al.
(author)
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The effect of steering feel on the crosswind performance of buses - Part I : Subjective assessment
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Journal article (other academic/artistic)abstract
- The steering feel is considered to be an important part of the on-centre handling characteristics of vehicles. Therefore, the steering feel is of interest when improving the crosswind performance of buses. In the present paper a methodology is proposed that utilizes a moving-base driving simulator to study the influence of steering feel on the subjective judgement of bus drivers regarding crosswind performance. Results achieved when using this method show that there exists a correlation between the steering feel and the subjective evaluation of crosswind performance. When the drivers are driving a bus with low crosswind sensitivity, it is shown that low yaw rate gradients are preferred for both the steering wheel torque and the steering wheel angle. For more crosswind-sensitive vehicles, the demand for higher yaw rate gradients increases. That is probably due to the increased need for corrections and the fact that more prompt driver corrections are facilitated by higher yaw rate gradients. It can therefore be concluded that, in order to help the driver in a crosswind situation, it would be valuable to be able to change the steering feel characteristics of the vehicle.
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| 8. |
- Juhlin, Magnus, 1975-, et al.
(author)
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The effect of steering feel on the crosswind performance of buses - Part II : Objective assessment and correlation with subjective judgements
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Journal article (other academic/artistic)abstract
- The steering feel is considered to be an important part of the on-centre handling characteristics of vehicles and therefore of interest when improving the crosswind performance of buses. In this paper a methodology is proposed which uses a moving-base driving simulator for studying the influence of steering feel on the objective judgement of crosswind performance. The results obtained with this method show that there exists a correlation between the steering feel and the objective evaluation of crosswind performance. The objective results show that the lateral deviation due to a crosswind gust is reduced for all levels of crosswind sensitivity when the yaw rate gradients referencing both the steering-wheel angle and the steering-wheel torque are increased, thereby minimising the maximum required steering power. This is in contrast to the subjective results, which showed that low yaw rate gradients were preferred when the centre of gravity was in the most forward position. The results presented in this study imply a great potential in using an adaptive steering system, since the steering feel that objectively is most suitable under crosswind excitation is not subjectively preferred for all the centre of gravity positions.
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| 9. |
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| 10. |
- Trobos, Margarita, 1980, et al.
(author)
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In vitro evaluation of barrier function against oral bacteria of dense and expanded polytetrafluoroethylene (PTFE) membranes for guided bone regeneration
- 2018
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In: Clinical Implant Dentistry and Related Research. - : Wiley. - 1523-0899. ; 20:5, s. 738-748
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Journal article (peer-reviewed)abstract
- Aim: This study evaluates biofilm formation and barrier function against Streptococcus oralis of nonresorbable polytetrafluoroethylene (PTFE) guided bone regeneration membranes having expanded (e-PTFE) and dense (d-PTFE) microstructure. Materials and Methods: Three e-PTFE membranes of varying openness, one d-PTFE membrane, and commercially pure titanium discs were evaluated. All e-PTFE membranes consisted of PTFE nodes interconnected by fibrils. The d-PTFE membrane was fibril-free, with large evenly spaced indentations. The surfaces were challenged with S. oralis and incubated statically for 2-48 h. Bacterial colonization, viability, and penetration were evaluated. Results: S. oralis numbers increased over time on all surfaces, as observed using scanning electron microscopy, while cell viability decreased, as measured by colony forming unit (CFU) counting. At 24 h and 48 h, biofilms on d-PTFE were more mature and thicker (tower formations) than on e-PTFE, where fewer layers of cells were distributed mainly horizontally. Biofilms accumulated preferentially within d-PTFE membrane indentations. At 48 h, greater biofilm biomass and number of viable S. oralis were found on d-PTFE compared to e-PTFE membranes. All membranes were impermeable to S. oralis cells. Conclusions: All PTFE membranes were effective barriers against bacterial passage in vitro. However, d-PTFE favored S. oralis biofilm formation.
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