| 1. |
- Aad, G., et al.
(författare)
-
- 2011
-
Tidskriftsartikel (refereegranskat)
|
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| 2. |
- Özkirimli, Umut
(författare)
-
Dying for your Homeland
- 2018
-
Ingår i: Ahval.
-
Tidskriftsartikel (populärvet., debatt m.m.)
|
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| 3. |
- Öztürk, Cüneyd, et al.
(författare)
-
On the Impact of Hardware Impairments on RIS-aided Localization
- 2022
-
Ingår i: IEEE International Conference on Communications. - 1550-3607. ; 2022-May, s. 2846-2851
-
Konferensbidrag (refereegranskat)abstract
- We investigate a reconfigurable intelligent surface (RIS)-aided near-field localization system with single-antenna user equipment (UE) and base station (BS) under hardware impairments by considering a practical phase-dependent RIS amplitude variations model. To analyze the localization performance under the mismatch between the practical model and the ideal model with unit-amplitude RIS elements, we employ the misspecified Cramér-Rao bound (MCRB). Based on the MCRB derivation, the lower bound (LB) on the mean-squared error for estimation of UE position is evaluated and shown to converge to the MCRB at low signal-to-noise ratios (SNRs). Simulation results indicate more severe performance degradation due to the model misspecification with increasing SNR. In addition, the mismatched maximum likelihood (MML) estimator is derived and found to be tight to the LB in the high SNR regime. Finally, we observe that the model mismatch can lead to an order-of-magnitude localization performance loss at high SNRs.
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| 4. |
- Aad, G., et al.
(författare)
-
- 2013
-
Ingår i: The European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6052. ; 73:3
-
Tidskriftsartikel (refereegranskat)
|
|
| 5. |
- Aad, G., et al.
(författare)
-
- 2011
-
swepub:Mat__t
|
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| 6. |
- Aad, G., et al.
(författare)
-
- 2013
-
Tidskriftsartikel (refereegranskat)
|
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| 7. |
- Anderson, Helén, et al.
(författare)
-
- 1997
-
Ingår i: Paper presented at the World Manufacturing Congress (Track IMM’97) in Auckland, New Zealand, November 18-21, 1997.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
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| 8. |
- Özkirimli, Umut
(författare)
-
You Are All Kurds Now
- 2018
-
Ingår i: Ahval.
-
Tidskriftsartikel (populärvet., debatt m.m.)
|
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| 9. |
- Aad, G., et al.
(författare)
-
- 2011
-
swepub:Mat__t (refereegranskat)
|
|
| 10. |
- Aad, G., et al.
(författare)
-
- 2011
-
swepub:Mat__t (refereegranskat)
|
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| 11. |
- Aad, G., et al.
(författare)
-
- 2012
-
swepub:Mat__t (refereegranskat)
|
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| 12. |
- Aad, G., et al.
(författare)
-
- 2012
-
swepub:Mat__t (refereegranskat)
|
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| 13. |
- Özgü, Alay, et al.
(författare)
-
End to End 5G Measurements with MONROE: Challenges and Opportunities
- 2018
-
Ingår i: 4th International Forum on Research and Technologies for Society and Industry (IEEE RTSI 2018). - : IEEE. - 9781538662823
-
Konferensbidrag (refereegranskat)abstract
- To be able to support diverse requirements of massive number of connected devices while also ensuring good user experience, 5G networks will leverage multi-access technolo- gies, deploy supporting operational mechanisms such as SDN and NFV, and require enhanced protocols and algorithms. For 4G networks, MONROE has been key to provide a common measurement platform and a set of methodologies available to the wider community. Such common grounds will become even more important and more challenging with 5G. In this paper, we elaborate on some key requirements for the design and implementation of 5G technologies and highlight the key challenges and needs for new solutions as seen in the context of 5G end-to-end measurements. We then discuss the opportunities that MONROE provides and more specifically, how a 5G-capable MONROE platform could facilitate these efforts.
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| 14. |
- Özkahraman, Özer, 1992-, et al.
(författare)
-
Combining Control Barrier Functions and Behavior Trees for Multi-Agent Underwater Coverage Missions
- 2020
-
Ingår i: Proceedings of 59th Conference on Decision and Control, 2020.
-
Konferensbidrag (refereegranskat)abstract
- Robot missions typically involve a number of desired objectives, such as avoiding collisions, staying connected to other robots, gathering information using sensors and returning to the charging station before the battery runs out.Some of these objectives need to be taken into account at the same time, such as avoiding collisions and staying connected, while others are focused upon during different parts of the executions, such as returning to the charging station and connectivity maintenance.In this paper, we show how Control Barrier Functions(CBFs) and Behavior Trees(BTs) can be combined in a principled manner to achieve both types of task compositions, with performance guarantees in terms of mission completion. We illustrate our method with a simulated underwater coverage mission.
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| 15. |
- Özkahraman, Özer, 1992-, et al.
(författare)
-
Data-Driven Damage Detection and Control Adaptation for an Autonomous Underwater Vehicle
- 2022
-
Ingår i: 61st IEEE Conference on Decision and Control (CDC), 2022.
-
Konferensbidrag (refereegranskat)abstract
- Underwater robotic exploration missions typically involve traveling long distances without any human contact.The robots that go on such missions risk getting damaged by the unknown environment, accruing great costs and missed opportunities.Thus it is important for the robot to be able to accommodate unknown changes to its dynamics as much as possible and attempt to finish the given mission, or at the very least move itself to a retrievable position.In this paper, we show how we can detect physical changes to the robot reliably (79\% on real robot data) and then incorporate these changes through adapting the model to the data followed by automated control redesign. We adopt a piecewise-affine (PWA) modelling of the dynamics that is well suited for low data regime learning of the dynamics and provides a structure for computationally efficient control synthesis.We demonstrate the effectiveness of the proposed method on a combination of real robot data and simulated scenarios.
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| 16. |
- Özkaya Sahin, Gülsen, et al.
(författare)
-
Potent Intratype Neutralizing Activity Distinguishes Human Immunodeficiency Virus Type 2 (HIV-2) from HIV-1
- 2012
-
Ingår i: Journal of Virology. - 1098-5514. ; 86:2, s. 961-971
-
Tidskriftsartikel (refereegranskat)abstract
- HIV-2 has a lower pathogenicity and transmission rate than HIV-1. Neutralizing antibodies could be contributing to these observations. Here we explored side by side potency and breadth of intratype and intertype neutralizing activity (NAc) in plasma of 20 HIV-1, 20 HIV-2 and 11 dually HIV-1/2 (HIV-D) seropositive individuals from Guinea-Bissau, West Africa. Panels of primary isolates, five HIV-1 and five HIV-2, were tested in a plaque reduction assay using U87.CD4-CCR5 cells as targets. Intratype NAc in HIV-2 plasma was found to be considerably more potent, and also broader, than intratype NAc in HIV-1 plasma. This indicates that HIV-2 infected individuals display potent type-specific neutralizing antibodies, whereas such a strong type-specific antibodies are absent in HIV-1 infection. Furthermore, potency of intratype NAc was positively associated with viral load of HIV-1, but not HIV-2, suggesting that NAc in HIV-1 infection is more antigen stimulation-dependent than in HIV-2 infection where plasma viral loads typically are at least tenfold lower than in HIV-1 infection. Intertype NAc of both HIV-1 and HIV-2 infected was instead of low potency. HIV-D subjects had NAc to HIV-2 with similar high potency as singly HIV-2 infected individuals, whereas neutralization of HIV-1 remained poor, indicating that the difference in NAc between HIV-1 and HIV-2 infections depends on the virus itself. We suggest that immunogenicity and/or antigenicity, meaning the neutralization phenotype, of HIV-2 is distinct from HIV-1, and that HIV-2 may display structures that favour triggering of potent neutralizing antibody responses.
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| 17. |
- Öztayşi, Başar, et al.
(författare)
-
Fuzzy Analytic Hierarchy Process with Interval Type-2 Fuzzy Sets
- 2014
-
Ingår i: Knowledge-Based Systems. - : Elsevier BV. - 0950-7051. ; 59, s. 48-57
-
Tidskriftsartikel (refereegranskat)abstract
- The membership functions of type-1 fuzzy sets have no uncertainty associated with it. While excessive arithmetic operations are needed with type-2 fuzzy sets with respect to type-1’s, type-2 fuzzy sets generalize type-1 fuzzy sets and systems so that more uncertainty for defining membership functions can be handled. A type-2 fuzzy set lets us incorporate the uncertainty of membership functions into the fuzzy set theory. Some fuzzy multicriteria methods have recently been extended by using type-2 fuzzy sets. Analytic Hierarchy Process (AHP) is a widely used multicriteria method that can take into account various and conflicting criteria at the same time. Our objective is to develop an interval type-2 fuzzy AHP method together with a new ranking method for type-2 fuzzy sets. We apply the proposed method to a supplier selection problem.
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| 18. |
- Gustavsson Tingvall, Patrik, et al.
(författare)
-
- 2011
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Research and Development (R&D) is a key component behind technological development and economic growth; therefore, understanding the drivers of R&D is crucial. An interesting question is the role of technology spillovers, transferred by trade, and their impact on firm R&D. Here we analyze not only how international and domestic inter- and intra-industry technology spillovers affect firm R&D but also the relatively unexplored issue of how relationship-specific interactions between buyer and seller affect such spillovers. We find international technology spillovers to be larger and more significant than domestic inter- and intra-industry spillovers. Moreover, relationship-specific interactions between seller and buyer enhance technology spillovers in general and international spillovers in particular.
|
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| 19. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
|
| 20. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
|
| 21. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
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| 22. |
- Özkılıç, Yasin Onuralp, et al.
(författare)
-
Influence of ceramic waste powder on shear performance of environmentally friendly reinforced concrete beams
- 2024
-
Ingår i: Scientific Reports. - : Springer. - 2045-2322. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- This investigation considered the usability of ceramic waste powder (CWP) in altered quantities in reinforced concrete beams (RCBs). In this way, it was aimed to reduce the environmental impacts of concrete by using CWP as a raw material in RCBs. 12 small-scale shear RCBs with the dimensions of 100 × 150 × 1000 mm were tested in this study. The variations of stirrups spacing and CWP ratio were examined in these specimens. The percentages of CWP by weight utilized in RCBs were 10%, 20%, and 30%, and stirrups spacings were adopted as 270 mm, 200 mm, and 160 mm. At the end of the study, it was determined that more than 10% CWP additive negatively affected the RCBs’ compressive strength. The load-carrying capacity reduced between 30.3% and 59.4% when CWP increased from 0% to 30% as compared to RCB with stirrups spacing of 270 mm without CWP. However, compared to RCB with stirrups spacings of 200 mm and 160 mm without CWP, there were decreases in the load-carrying capacity as 21.4%–54.3% and 18.6%–54.6%, respectively. While the CWP ratio increased, the specimens with 160 mm, 200 mm, and 270 mm stirrups spacings obtained a lower maximum load value. However, with the increase of the CWP ratio in the specimens with 160 mm stirrups spacing, RCBs reached the maximum load-carrying capacity at an earlier displacement value. When stirrups spacing was selected as 270 mm, it was observed that the maximum load-carrying capacity of RCBs reached at a similar displacement value as the CWP ratio increased. Besides, it was resulted that the bending stiffness of RCBs reduced as the quantity of CWP enhanced. The bending stiffness decreased by 29.1% to 66.4% in the specimens with 270 mm stirrups spacing, 36.3% to 20.2% with 200 mm stirrups spacing, and 10.3% to 36.9% with 160 mm stirrups spacing. As an implication of the experiments, the use of CWP up to 10% in RCBs was realized as an economical and environmental approach and is suggested. There is some evidence to report that making use of CWP may be considered to be ecologically benign. This is due to the fact that reusing CWP may significantly reduce CO2 emissions, save energy, and reduce total power consumption. Furthermore, the experimental results were compared to the analytical calculations.
|
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| 23. |
|
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| 24. |
- Öztürk, Ebru, et al.
(författare)
-
The veil as an object of right-wing populist politics : A comparative perspective of Turkey, Sweden, and France
- 2022
-
Ingår i: Identities. - 1070-289X .- 1547-3384. ; 29:4, s. 538-555
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, we comparatively analyse radical right-wing parties' intervention into the veil debate in Turkey, Sweden, and France which are characterised by different understandings of legal and normative secularism. We explore the intersection of gender and religion in the dynamic formation of populist categories and how they can be mobilised differently along the vertical and the horizontal axes by the example of the veil. In all three countries we have analysed capitalise on gender, religiosity and secularity, and the veil is exploited in drawing boundaries between the People and non-People but also between the People and the Elites. In this way, the meanings attributed to the veil are used as a mechanism of exclusion and of drawing the boundaries through gendered narratives of who belongs to the People.
|
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| 25. |
- Aad, G., et al.
(författare)
-
- 2012
-
swepub:Mat__t (refereegranskat)
|
|
| 26. |
- Olsson Holmström, Helena, et al.
(författare)
-
- 2014
-
Ingår i: Proceedings of the Euromicro Conference. - : IEEE. ; , s. 9-16
-
Konferensbidrag (refereegranskat)abstract
- In most software development companies the road mapping and requirements prioritization process is a complex process in which product management experiences difficulties in getting timely and accurate customer feedback. The feedback loop from customers is slow and often there is a lack of mechanisms that allow for efficient customer data collection and analysis. As a result, there is the risk that requirements prioritization becomes opinion-based rather than data-driven, and that R&D investments are made without an accurate way of continuously validating whether they correspond to customer needs. We call this phenomenon the 'open loop' problem, referring to the challenges for product management to get accurate and timely feedback from customers. To address this problem, we develop the HYPEX model (Hypothesis Experiment Data-Driven Development) that supports companies in running feature experiments to shorten customer feedback loops. We evaluate the model in three software development companies and observe how feature experiments increase the opportunity for data-driven software development.
|
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| 27. |
- Aad, G., et al.
(författare)
-
- 2015
-
Tidskriftsartikel (refereegranskat)
|
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| 28. |
- Özeren, Hüsamettin Deniz, et al.
(författare)
-
Ranking Plasticizers for Polymers with Atomistic Simulations; PVT, Mechanical Properties and the Role of Hydrogen Bonding in Thermoplastic Starch
- 2020
-
Ingår i: ACS Applied Polymer Materials. - : American Chemical Society (ACS). - 2637-6105. ; 2:5, s. 2016-2026
-
Tidskriftsartikel (refereegranskat)abstract
- Virgin biopolymers are often brittle and, therefore, need the addition of plasticizers to obtain the required mechanical properties for practical applications, e.g. in bags and disposable kitchen items. In this article, based on a combined experimental and modelling approach, it is shown that it is possible to rank molecules with respect to their plasticization efficiency (depression in glass transition temperature with PVT data and reduced stiffness and strength) using molecular dynamics simulations. Starch was used as the polymeric matrix material due to its promising potential as a sustainable, eco-friendly, biobased replacement for fossil-based plastics. Three polyols (glycerol, sorbitol and xylitol), two ethanolamines and glucose were investigated. The results indicate that molecular simulations can be used to find the optimal plasticizer among a set of candidates, or to design/identify better plasticizers in a complex polymer system. Glycerol was the most efficient of the six plasticizers, explained by it forming the least amount of hydrogen bonds, having the shortest hydrogen bond lifetimes and low molecular rigidity. Hence, not only was it possible to rank plasticizers, the ranking results could also be explained by the simulations.
|
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| 29. |
- Özkahraman, Özer, 1992-, et al.
(författare)
-
Collaborative Navigation-Aware Coverage in Feature-Poor Environments
- 2022
-
Ingår i: International Conference on Intelligent Robots and Systems (IROS), 2022.
-
Konferensbidrag (refereegranskat)abstract
- Multi agent coverage and robot navigation are two very important research fields within robotics. However, their intersection has received limited attention. In multi agent coverage, perfect navigation is often assumed, and in robot navigation, the focus is often to minimize the localization error with the aid of stationary features from the environment.The need for integration of the two becomes clear in environments with very sparse features or landmarks, for example when a group of Autonomous Underwater Vehicles (AUVs) are to search a uniform seafloor for mines or other dangerous objects.In such environments, localization systems are often deprived of detectable features to use that could increase their accuracy.In this paper we propose an algorithm for doing navigation aware multi agent coverage in areas with no landmarks.Instead of using identical lawn mower patterns, we propose to mirror every other pattern to enable the agents to meet up and makeinter-agent measurements and share information regularly. This improves performance in two ways,global drift in relation to the area to be covered is reduced, and local coverage gaps between adjacent patterns are reduced.Further, we show that this can be accomplished within the constraints of very limited sensing, computing and communication resources that most AUVs have available.The effectiveness of our method is shown through statistically significant simulated experiments.
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| 30. |
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| 31. |
- Özlü, Neslihan, 1980-
(författare)
-
The Heterogeneity of Behavior in Operations Processes : Empirical Evidence
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Behavioral science research has established that observed human behavior may deviate considerably from model suggestions. In addition to the realization that there is no such thing as standardized human behavior, there are also substantial differences in how people deviate from the model: Different individuals make dissimilar decisions in the same situation when using the same information. Recently, behavioral operations management has seen an increased focus on understanding the role of humans in the decisions and processes these models aim to capture. However, still little is known about the factors that determine the observed behavioral heterogeneity.Advancements in technology have made it possible to collect and analyze data at granular levels. The availability of such detailed data has increased the ability of the behavioral sciences to examine behavior with techniques from data science and empirical analysis. Therein lies the possibility of capturing the human role in processes and improving them according to the results.The overarching purpose of this dissertation is to enhance the understanding of what drives heterogeneity of behavior in operations processes. To fulfill this purpose, this dissertation presents four studies; each targeting drivers of the heterogeneity in different operations processes. The four studies focus on decision making, determining choices, and forecasting in different empirical settings.The first study analyzes the ordering behavior of purchasing agents when placing orders involving uncertain lead times with suppliers. Purchasers seem to rely on their prior encounters with suppliers and add safety times depending on the type and recency of their experiences with them. This behavior may lead to early ordering to avoid late deliveries. Our results inform behavioral operations by examining the mechanism behind experiential learning in an industrial setting. The second study explores e-commerce customers’ choices of fulfillment methods. It disentangles the importance of a customer’s perceived delivery convenience from factors such as order fulfillment speed and price of delivery.The third study investigates industrial purchasing again, this time analyzing how purchasers time their orders depending on previous experiences with specific suppliers and the experiences of peers. Our findings contribute to the literature on supply chain disruptions and the effect of rare events on an individual’s ordering decisions, and highlight how individuals learn from their own as well as from peers' experiences. The fourth study focuses on the effect of lifetime experiences on professionals who are tasked with forecasting inflation over an extended period. We provide evidence that systematic differences in forecasts of inflation across generations of economic forecasters are due to varied lifetime experiences. This outcome adds to the literature on experiential effects by emphasizing the importance of individual judgment versus available information in forecasting tasks.All studies use field data collected from several companies to explore drivers of behavioral heterogeneity in operations processes. Their findings permit a better understanding of what drives variations of behavior in different operations settings, which through further elaboration and research can help businesses set more targeted policies and management priorities.
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| 32. |
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| 33. |
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| 34. |
- Özger, Mustafa, et al.
(författare)
-
Energy-Efficient Transmission Range and Duration for Cognitive Radio Sensor Networks
- 2021
-
Ingår i: IEEE Transactions on Cognitive Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 2332-7731. ; , s. 1-1
-
Tidskriftsartikel (refereegranskat)abstract
- Cognitive Radio (CR) promises an efficient utilization of radio spectrum resources by enabling dynamic spectrum access to overcome the spectrum scarcity problem. Cognitive Radio Sensor Networks (CRSNs) are one type of Wireless Sensor Networks (WSNs) equipped with CR capabilities. CRSN nodes need to operate energy-efficiently to extend network lifetime due to their limited battery capacity. In this paper, for the first time in literature, we formulate the problem of finding a common energy-efficient transmission range and transmission duration for all CRSN nodes and network deployment that would minimize the energy consumed per goodput per meter toward the sink in a greedy forwarding scenario. Results reveal non-trivial relations for energy-efficient CRSN transmission range and duration as a function of nine critical network parameters such as primary user activity levels. These relations provide valuable insights for detailed CRSN designs prior to deployment.
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| 35. |
|
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| 36. |
- Miranda Carranza, Pablo, 1972-, et al.
(författare)
-
- 2009
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper gives an overview of the approach of working methods at the Aedas R&DComputational Design and Research [CDR] Group. It first contextualizes research inarchitectural practice and tries to propose an explanation for the difficulties inimplementing it; then explains the evolution of the groups’ computing approach frombespoke to heuristic sets of lightweight applications. It concludes with examples of thedeveloped computational design approach.
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| 37. |
- Johansson, Börje, et al.
(författare)
-
- 2006
-
Ingår i: The Internationalization of Corporate R&D. - Östersund : Institutet för tillväxtpolitiska studier (ITPS). ; , s. 89-104
-
Bokkapitel (populärvet., debatt m.m.)
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| 38. |
- Ulfsdotter, Boel, 1959
(författare)
-
- 2015
-
Ingår i: Journal of Scandinavian Cinema. - : Intellect. - 2042-7891 .- 2042-7905. ; 5:3, s. 259-270
-
Tidskriftsartikel (refereegranskat)abstract
- This article discusses the various narrative, performative and cinematic strategies of Swedish comedy team Hans Alfredson and Tage Danielsson (aka Hasse&Tage) as they moved from stage to screen through an analysis of their second film, Att angöra en brygga/Docking the Boat (Danielsson, 1965). The theoretical point of departure is the question of the relationship between classical narrative structure and plots based on a series of gags. Through a combination of formal analysis of film style and mise-en-scène in select film sequences and a general discussion of popu- lar cultural references, gags, acting style and visual framing, the article reveals that gags in the film usually serve a narrative purpose. The sophisticated appropriation of central themes representative of New Wave aesthetics demonstrates that Docking the Boat is only partially derivative of Hasse&Tage’s ventures as stage comedians. The article concludes with a suggestion that previous experiences from a variety of media platforms had a strong impact on their ability to develop a unique and highly cinematic visual and intellectually sophisticated film style.
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| 39. |
- Birgersson, Tobias, 1973
(författare)
-
- 2018
-
Ingår i: November 10 -18th 2018, Täby Kulturcentrum, Karby Gård, Sweden..
-
Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)
|
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| 40. |
- Aad, G., et al.
(författare)
-
- 2012
-
swepub:Mat__t (refereegranskat)
|
|
| 41. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
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| 42. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
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| 43. |
- Aad, G., et al.
(författare)
-
- 2015
-
Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368 .- 1550-7998. ; 91:5
-
Tidskriftsartikel (refereegranskat)
|
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| 44. |
- Özgünoglu, Mehmet, 1989, et al.
(författare)
-
Numerical Assessment of Cavitation Erosion for a Nozzle Flow Configuration
- 2021
-
Ingår i: 11th International Symposium on Cavitation (CAV2021).
-
Konferensbidrag (refereegranskat)abstract
- The main purpose of this study is to numerically investigate and predict the cavitation erosion mechanisms in a nozzle flow configuration. To do this, an injector type geometry is numerically investigated with the open-source CFD package OpenFOAM. A compressible Euler approached is applied for two operating conditions, where results are compared with other studies from the literature. Spectral statistics and maximum surface pressure results are compared with experiments. Results show that the proposed modelling approach is capable to explain main cavitation structures that promotes erosion.
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| 45. |
- Özkahraman, Özer, 1992-, et al.
(författare)
-
Efficient Navigation Aware Seabed Coverage using AUVs
- 2021
-
Ingår i: Proceedings of 2021 IEEE International Conference on Safety, Security, and Rescue Robotics (SSRR), October 25-27 2021, New York, USA..
-
Konferensbidrag (refereegranskat)abstract
- Area coverage and robot navigation are two important research fields within robotics. However, their intersection has received limited attention. In coverage problems, perfect navigation is often assumed, and in robot navigation, the focus is often to minimize the localization error while traveling a given trajectory.The need for integration of the two becomes clear in environments with very sparse features or landmarks, for example when an Autonomous Underwater Vehicle (AUV) is to search the seafloor for dangerous objects, such as mines.The potential consequences of missing a mine due to navigation errors can be catastrophic.If the localization error is large, a trajectory that was designed to guarantee complete coverage might have missed significant parts of the area. Thus, the coverage trajectory must be planned with the navigation performance in mind, applying a combination of using large enough planned overlaps of sensor footprints to account for the position uncertainty, and reducing this uncertainty by re-visiting the known sparse landmarks.In this paper we compute trajectories that guarantee coverage for a given area under assumptions on worst case localization error growth.We further more compute upper bounds for how large areas can be covered using common coverage patterns and a single landmark, which leads to bounds on how sparse the landmarks can be in the regions to be covered.
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| 46. |
- Özkaya Sahin, Gülsen, et al.
(författare)
-
Generation of neutralizing antibodies and divergence of SIVmac239 in cynomolgus macaques following short-term early antiretroviral therapy.
- 2010
-
Ingår i: PLoS Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 6:9
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Tidskriftsartikel (refereegranskat)abstract
- Neutralizing antibodies (NAb) able to react to heterologous viruses are generated during natural HIV-1 infection in some individuals. Further knowledge is required in order to understand the factors contributing to induction of cross-reactive NAb responses. Here a well-established model of experimental pathogenic infection in cynomolgus macaques, which reproduces long-lasting HIV-1 infection, was used to study the NAb response as well as the viral evolution of the highly neutralization-resistant SIVmac239. Twelve animals were infected intravenously with SIVmac239. Antiretroviral therapy (ART) was initiated ten days post-inoculation and administered daily for four months. Viral load, CD4(+) T-cell counts, total IgG levels, and breadth as well as strength of NAb in plasma were compared simultaneously over 14 months. In addition, envs from plasma samples were sequenced at three time points in all animals in order to assess viral evolution. We report here that seven of the 12 animals controlled viremia to below 10(4) copies/ml of plasma after discontinuation of ART and that this control was associated with a low level of evolutionary divergence. Macaques that controlled viral load developed broader NAb responses early on. Furthermore, escape mutations, such as V67M and R751G, were identified in virus sequenced from all animals with uncontrolled viremia. Bayesian estimation of ancestral population genetic diversity (PGD) showed an increase in this value in non-controlling or transient-controlling animals during the first 5.5 months of infection, in contrast to virus-controlling animals. Similarly, non- or transient controllers displayed more positively-selected amino-acid substitutions. An early increase in PGD, resulting in the generation of positively-selected amino-acid substitutions, greater divergence and relative high viral load after ART withdrawal, may have contributed to the generation of potent NAb in several animals after SIVmac239 infection. However, early broad NAb responses correlated with relatively preserved CD4(+) T-cell numbers, low viral load and limited viral divergence.
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| 47. |
- Özkaya Sahin, Gülsen
(författare)
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Studies on Potency and breadth of HIV-1, HIV-2 and SIV neutralizing antibody responses
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Even though the relative contribution of neutralizing antibodies (Nab) to prevent progression to AIDS during HIV-1 infection is still unclear, the induction of broadly NAb directed against HIV-1 through vaccination is considered to represent an important goal for the development of HIV-1 vaccines. Factors contributing to the induction of NAb may include the strength and duration of antigenic stimulation, the preservation of CD4+ T and B cells, the conformation of the HIV-1 envelope glycoprotein complex (Env), and the evolution of Env during infection. To understand these relationships, the experimental model of pathogenic SIV infection in cynomolgus macaques and comparison of HIV-1 and HIV-2 infections in humans were used in this thesis. In the macaque model we studied in parallel the appearance of NAb and evolution of Env. For the preservation of SIV-specific cellular immune responses, early anti-retroviral treatment was provided. The main finding from this study was that the macaques that controlled viral load after treatment discontinuation displayed limited virus population genetic diversity and divergence, and had an early broad NAb response. On the other hand, the macaques with no or transient control of viremia showed greater virus diversity and divergence, and potent NAb response during the early period of infection. We propose that the early phase of viral evolution and the antigenic stimulation contributes to the development of NAb and control of viremia. In humans, HIV-2 is known to be less transmissible and less pathogenic than HIV-1. Therefore, valuable insight can be gained into HIV immunopathogenesis from studies of HIV-2 cohorts with their high proportion of long-term non-progressors. In order to analyze differences in NAb in these infections, we compared, side by side, the breadth and potency of neutralizing activity (NAc) in plasma of HIV-1, HIV-2, and dually HIV-1/2 (HIV-D) infected individuals from Guinea-Bissau against HIV-1 and HIV-2 virus panels. The striking finding was that NAc in HIV-2 plasma against HIV-2 isolates was broader and more potent than NAc in HIV-1 plasma against HIV-1 isolates. Moreover, HIV-D positive individuals had broader and more potent NAc against HIV-2 isolates than HIV-1 isolates, indicating distinct immunogenicity and/or antigenicity of HIV-2 compared to HIV-1. We next analyzed the relative role of IgG and IgA for NAc in HIV-1, HIV-2 and HIV-D plasma. Similarly to the plasma NAc, IgG neutralizing antibodies were found to be more potent in HIV-2 plasma against HIV-2 compared to IgG from HIV-1 plasma against HIV-1. Interestingly, while HIV-2 neutralizing IgA was frequently detected in plasma of HIV-2 infected individuals, HIV-1 neutralizing IgA could rarely be demonstrated in HIV-1 plasma. To study humoral immunity in HIV-1 and HIV-2 infections further, we investigated the role of complement (C’) in antibody-dependent complement-mediated inactivation. Here results showed that the C’ effect on antiviral activity against HIV-2 was more pronounced in HIV-2 plasma than the C’ effect on HIV-1 plasma against HIV-1. Analysis of HIV-D plasma corroborated that the antibody-dependent complement-mediated inactivation was more efficient against HIV-2. This finding suggests that antibody binding to HIV-2 Env facilitates efficient use of C’. In summary, this thesis may provide insights into the nature of broad and potent neutralizing humoral immune responses.
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| 48. |
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| 49. |
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| 50. |
- Özlü, Neslihan, 1980-, et al.
(författare)
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Better safe than sorry: An empirical investigation of the role of purchaser experience
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The lead times of suppliers vary considerably, causing manufacturers to suffer from low service levels and also to accumulate material and product inventories. Although various inventory control and production planning models have been studied in the operations management literature, there is scant research on the behavioral aspects of purchasing decisions beyond the ordering quantity. Drawing on transaction-level purchasing data from a large European manufacturer, we investigate the purchasers' ordering behavior under variable lead times. We examine the learning of the purchasers from their experiences with the suppliers, in terms of both how many encounters they had with the suppliers and how the experiences went. We apply two-part regression models with fixed effects to estimate the effects of purchaser experience and past supplier performance. Our analysis reveals insights into the purchasers' learning process, indicating that they rely on their prior encounters with suppliers and change their ordering behavior as they gain experience. We show that the decision to add positive safety time is driven mainly by supplier performance. With experience, purchasers become more eager to use safety time as a buffering strategy, while simultaneously learning not to overreact to past supplier performance. Furthermore, purchasers give higher weights to the normalized lateness/tardiness of their most recent encounters than to earlier ones. Our results highlight the importance of understanding the behavioral aspects that impact purchasing operations, due to which employees might have objectives that are misaligned with the company goals. This finding also points to a need for further automation of ordering tasks as well as the incorporation of behavioral factors to decision support systems.
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