| 1. |
- Persson, Fredrik, et al.
(författare)
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USING SIMULATION TO DETERMINE THE SAFETY STOCK LEVEL FOR INTERMITTENT DEMAND
- 2017
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Ingår i: 2017 WINTER SIMULATION CONFERENCE (WSC). - : IEEE. - 9781538634288 ; , s. 3768-3779
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Konferensbidrag (refereegranskat)abstract
- Safety stock calculations are difficult for products with intermittent demand, long production lead times, and high monetary values. Theoretically, forecasts can be used to reduce the need for safety stocks. A high precision forecast minimizes the need for safety stock and forecast evaluation measurements can be used to calculate the safety stock level. However, a more realistic determination of safety stock levels can he obtained by simulation. In this paper, simulation is used to model and experiment on a case with three end products in order to determine the relationship between safety stock levels and service levels. Also, a comparison is made with theoretically calculated safety stocks to see how well basic theoretical models for safety stock calculations fulfill the requirements of service level. The result is that simulation can provide a much more accurate determination of safety stock levels for intermittent demands than theoretical calculations.
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| 2. |
- Espinoza, Fredrik, et al.
(författare)
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Analysis of Open Answers to Survey Questions throughInteractive Clustering and Theme Extraction
- 2018
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Ingår i: Proceedings of Conference on Human Information Interaction & Retrieval. - New York, New York, USA : ACM Digital Library. ; , s. 317-320
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Konferensbidrag (refereegranskat)abstract
- This paper describes design principles for and the implementation of Gavagai Explorer—a new application which builds on interactive text clustering to extract themes from topically coherent text sets such as open text answers to surveys or questionnaires.An automated system is quick, consistent, and has full coverage over the study material. A system allows an analyst to analyze more answers in a given time period; provides the same initial results regardless of who does the analysis, reducing the risks of inter-rater discrepancy; and does not risk miss responses due to fatigue or boredom. These factors reduce the cost and increase the reliability of the service. The most important feature, however, is relieving the human analyst from the frustrating aspects of the coding task, freeing the effort to the central challenge of understanding themes. Gavagai Explorer is available on-line at http://explorer.gavagai.se
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| 3. |
- Fritzsche, Joachim, 1977, et al.
(författare)
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A lipid-based passivation scheme for nanofluidics
- 2012
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Ingår i: 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2012; Okinawa; Japan; 28 October 2012 through 1 November 2012. - 9780979806452 ; , s. 1876-1878
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Konferensbidrag (refereegranskat)abstract
- Stretching DNA in nanochannels allows for direct, visual studies of genomic DNA at the single molecule level. In order to facilitate the study of the interaction of linear DNA with proteins in nanochannels, we have implemented a highly effective passivation scheme based on lipid bilayers. We show long-term passivation of nanochannel surfaces to several relevant reagents and demonstrate that the performance of the lipid bilayer is significantly better compared to standard bovine serum albumin-based passivation. Moreover, we demonstrate how the passivated devices allow us to monitor single DNA cleavage events during enzymatic degradation.
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| 4. |
- Gebert Persson, Sabine, et al.
(författare)
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Public and private networks in tourism – : barriers to network identity construction and commitmen
- 2019
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Konferensbidrag (refereegranskat)abstract
- IntroductionDestinations all over the world encompass a broad range of stakeholders who all aspire to increase the tourism industry to accomplish regional development. At these destinations, there are many different stakeholders, who have mutual interest in a specific region, and there are different attempts to promote cooperation for joint efforts to attract visitors. Moreover, there is an increasing drive for municipalities to influence the tourism business as part of their regional development (Tillväxtverket, 2017).However, the aforementioned development of destinations has proven to involve competing interests between local, national and international stakeholders. Although private enterprises, the municipalities and on-governmental organizations, and residents have a common, or at least partly overlapping, interest in the development of a specific destination, competing interests will occasionally occur (c.f. Elbe et al., 2018). For instance, private businesses, like small local entrepreneurs, could be in direct competition with national or international corporations, despite the fact that they may have much to gain from joint marketing efforts (c.f. investment in a common brand). Similarly, public1organizations have a shared interest in the development of the tourism industry to increase tax revenues and job creation. However, municipalities have a greater responsibility for communities and its residents.As in many other sectors, public and private interactions are common within the tourism industry due to an overall reduction in public sector funding (Valente et al., 2015). Relationships between public and private actors are also set up to conjointly pool resources, share risks in the process of building, maintaining and developing public services (Keränen, 2017). Interactions between public-private actors have been acknowledged as important since these relationships enable firms to influence decisions within areas such as the public sector, rules and actions that can affect how the firm is perceived as legitimate or not (Hadjikhani, Lee, & Ghauri, 2008; Jansson, Saqib, & Sharma, 1995) but also as ways to develop new and existing resources. However, research has shown that uncertainty tends to be rather high in these relationships and the roles that the actors play are consequently dynamic and unclear. This in turn also affects how the actors perceive the cooperation between public and private actors (Keränen, 2017) and their commitment to these types of networks (Elbe et al., 2018). The sought after commitment would be enhanced if a mutual identity could be constituted; still the identity is established from how the stakeholders perceive their roles and relations to each other. So how could the identity of public actors merge with the identity of private actors to establish a mutual and common identity?Despite the apparent advantage to create a network to coordinate mutual, or at least overlapping, interests, it has proven to entail a number of difficult issues of which some will be addressed below. The combination of private and public stakeholders in one organization may have implications for its role and commitments (c.f. Elbe et al. 2009; 2018) i.e. it could influence the perceived identity construction of its constituents. The combination of public and private interests in the same organization could create tension; one perspective could have precedence over the other. For instance, if a publicly funded organization considers it to be its mission to only enhance businesses, there are stakeholder who could be overlooked, such as permanent residents, community services, and other lines of industry. Although the established networks are intended to work towards common goals, there may still be implicit and ambiguous goals, roles and identity formations.2The organizing of public and private interests in order to transform a place and its characteristics into a destination has proven to be a complex process. More research is needed in order to bring further clarity into factors affecting these types of relationships in terms of activities and resources (de Araujo and Bramwell, 2002) as well as how this affects the actors. Although there is a growing scholarly interest in public-private relationships, additional knowledge is needed on how the processes of these types of cooperation evolve (de Araujo and Bramwell, 2002). This is especially so in the context of created networks where the network is constructed rather than emerging and where the aim is to foster and manage activities, resource interactions and actor bonds.This paper sets out to further the understanding of interaction processes where public and private actors attempt to find ways to cooperate on a common issue. This is done by analyzing how the identity of a created network, consisting of public and private actors, develops over time. This paper focuses on explaining how a created network develops over time and why it evolves in the way it does. The purpose is to identify possible barriers to identity construction in a created network consisting of public and private actors. This is done through a case taking its point of departure in the decision of a major infrastructural investment in a destination in Sweden: the building of a new cruise quay on Gotland.Created public-private cooperation – previous research.Interactions between public-private actors have been acknowledged as important since these relationships enable firms to influence decisions within different areas such as the public sector, rules and actions (Keränen, 2017; Elbe et al., 2018) but also as ways to develop new and existing resources. These co-operations are encouraged by governments in many countries as interactions can facilitate the discussions and decisions related to how different activities evolve and are coordinated as well as how public resources are distributed. Moral responsibility and a way to recover citizens’ trust for politicians’ abilities to deliver on electoral pledge when resources are scarce has been emphasized as a reason for cooperation between public and private actors (Velotti, Botti & Vesci, 2012). In a tourism context, private-public cooperation can also increase the competitive advantage of destinations (Kotler et al., 1993).Over the last decades, a growing number of designated organizations for the coordination of tourist actors have been established using the concept of: Destination Management Organizations, DMO (c.f. Elbe et al. 2009). According to UNWTO (2018), the DMO’s3role should, “be to lead and coordinate activities under a coherent strategy in pursuit of this common goal.” The argument in research, and in practice, has been that these destination organizations can manage marketing and coordinate different actors from varying sectors in the society. Through this, it is assumed that the destination through facilitation of interactions among local actors and creation of networks can stimulate economic growth (Elbe et al., 2018). Hence, specific organizations are politically created to facilitate regional development. In addition, DMOs are proposed as a coalition of many organizations and interest although in practice, these organizations have proven to be composed in different ways, with varying performance (Tillväxtverket 2017). In order to understand the accomplishment the sought-after coordination of diverse stakeholder interests, a network approach has been suggested that encompasses inter-organizational relations (Elbe et al. 2018). The proposed network approach could take into account relations between organizations, not only limited to intra-organizational management models that do not encompass all stakeholders.Despite the numerous potential advantages of public-private interactions, they can be time- consuming and difficult as the participants come from different sectors and with deviating interests. Therefore, actors can perceive a risk that their power and influence may decrease. This can also lead to a lack of trust between the actors (de Araujo & Bramwell, 2002).Tensions and paradoxesInteraction between business actors are built around an economic rational. An assumption is that without economic incentives, interactions between business actors in networks will not come about (Håkansson, 1982; Finke et al., 2017). Different types of resources such as financial resources (capital), physical resources (time, technologies, people) and informational resources (knowledge) are exchanged and combined in new and unique ways through the interactions. Resources are through inherently dynamic and can always be used in new combinations within one relationship or in other relationships (Baraldi et al., 2012). An important condition and a factor influencing the interaction processes are the norms and perceptions of what constitutes the rules of the game. Through the interactions new norms for exchange can form and influence the continuation of the exchange. Whether to engage in the cooperation or not will be affected by previous experiences and expectations as expressed by Mousas and Ford (2009, p. 497): “Recurrent episodes are affected by the perceptions of the participants of their previous interactions and by their expectations of the future.” These exchange relationships, constitute the context in which interaction4processes between actors takes place (Easton & Håkansson, 1996; Håkansson & Ford, 2002; Håkansson & Waluszewski, 2002, 2007; Ritter, 2000).In tourist destinations, many of the resources used to attract tourists are public and common goods. The question of who owns these common goods is not always clear. Beaches, lakes, museums, culture heritage buildings are all resources that can attract tourists but that are public. Exchange relationships and agreement on how these public resources are exploited becomes essential for the survival of those organizations involved in developing act
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| 5. |
- Karlsson, Fredrik, et al.
(författare)
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Sensor Fused Indoor Positioning Using Dual Band WiFi Signal Measurements
- 2015
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Ingår i: 2015 European Control Conference (ECC). - 9783952426937 ; , s. 1669-1672
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Konferensbidrag (refereegranskat)abstract
- In this paper, signal strengths from known WiFi access points are used together with a particle filter to perform indoor navigation. It is shown that more information is obtained by using signals of both 2.4 and 5.0 GHz, compared to using only one frequency. Thus, using both frequencies provides a more accurate positioning. The second contribution is an algorithm where WiFi measurements are combined with pedestrian dead reckoning (PDR), which is based on step counting using an accelerometer and hypotheses of the heading using a gyroscope. This was found to provide further accuracy compared to more conventional methods.
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| 6. |
- Persson, Fredrik, 1979, et al.
(författare)
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Local conformation of confined DNA studied using emission polarization anisotropy
- 2010
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Ingår i: Biophysical Society 54th Annual Meeting.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- When confined in nanochannels with dimensions smaller than the DNA radius of gyration, DNA will extend along the channel. We investigate long DNA confined in nanochannels, using fluorescence microscopy and intercalated dyes. Studies of the dynamics and statics of DNA in such nanoscale confinements as a function of e.g. degree of confinement and ionic strength have yielded new insights into the physical properties of DNA with relevance for applications in genomics as well as fundamental understanding of DNA packaging in vivo. Our work extends the field by not only studying the location of the emitting dyes along a confined DNA molecule but also monitoring the polarization of the emitted light. By measuring the emission polarized parallel and perpendicular to the extension axis of the stretched DNA, information on the local spatial distribution of the DNA backbone can be obtained. Comparing polarizations in two directions for DNA confined in channels of effective diameters of 85 nm and 170 nm reveals a striking difference. Whereas the DNA in the larger channels shows an isotropic polarization of the emitted light, the light is to a large extent polarized perpendicular to the elongation of the DNA in the smaller channels. We expect this technique to have a large impact on the studies of changes in DNA conformation induced by protein binding or during DNA compactation as well as in fundamental polymer physics studies of DNA in confined environments, for example in bacterial spores and viruses.
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| 7. |
- Persson, Fredrik, 1979, et al.
(författare)
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Local conformation of confined DNA studied using emission polarization anisotropy
- 2010
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Ingår i: NanoBioTech-Montreux 2009.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In nanochannels with dimensions smaller than the DNA radius of gyration, DNA will extend along the channel. We investigate long DNA confined in nanochannels using fluorescence microscopy and intercalated dyes. Studies of the dynamics and statics of the DNA extension or position in such nanoscale confinements as a function of e.g. DNA contour length, degree and shape of confinement as well as ionic strength have yielded new insights in the physical properties of DNA with relevance for applications in genomics as well as fundamental understanding of DNA packaging in vivo. Our work extends the field by not only studying the location of the emitting dyes along a confined DNA molecule but also monitoring the polarization of the emitted light. We use intercalating dyes (YOYO-1) whose emission is polarized perpendicular to the DNA extension axis, and by measuring the emission polarized parallel and perpendicular to the extension axis of the stretched DNA, information on the local spatial distribution of the DNA backbone can be obtained. The results obtained are analogous to linear dichroism (LD) but on a single-molecule level, and obtained in a highly parallel fashion. We will discuss results in shallow (60 nm) and deep (180 nm) channels and describe an example of how the technique can be used to investigate non-uniform stretching of DNA on the single molecule level. Comparing polarizations in two directions for DNA confined in channels of effective diameters of 85 nm and 170 nm reveals a striking difference. Whereas the DNA in the larger channels shows an isotropic polarization of the emitted light, the light is to a large extent polarized perpendicular to the elongation of the DNA in the smaller channels. The ratio of the polarization parallel and perpendicular to the elongation direction, I|| / I⊥, is a measure of the relative local orientation of the DNA backbone. We believe that this technique will have a large impact on the studies of changes in DNA conformation induced by protein binding or during DNA compactation as well as in fundamental polymer physics studies of DNA in confined environments, for example in bacterial spores and viruses.
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| 8. |
- Persson, Fredrik, et al.
(författare)
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Polarization anisotropy of DNA in nanochannels
- 2008
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Ingår i: ; , s. 668-670
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Konferensbidrag (refereegranskat)abstract
- The local alignment of DNA stretched in nanofluidic channels is measured using polarization sensitive detection. With increased degree of stretching the polarization anisotropy increases both in the deGennes and the Odijk regime. The technique is expected to find use in studies of, for example, local conformational changes in polymer physics in confined spaces, studies of protein-DNA interactions and compactation of DNA.
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| 9. |
- Persson, Fredrik, et al.
(författare)
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Supply chain dynamics in the SCOR model : A simulation modeling approach
- 2012
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Ingår i: Proceedings of the 2012 Winter Simulation Conference (WSC). - Piscataway, NJ, USA : IEEE. ; , s. 1-12
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Konferensbidrag (refereegranskat)abstract
- Supply Chain Simulation (SCS) is today a well-defined branch of discrete-event simulation applications. The differences between different applications are usually small, but in the case of SCS, models tend to be larger, take longer time to build and are harder to validate. To remedy some of these issues in SCS, we propose to use the SCOR model (Supply Chain Operations Reference Model) as a tool to speed up the simulation modeling of supply chains. The SCOR model can be useful in the conceptual phase, the modeling phase, and in the experimental phase of a simulation project. In SCOR Template, a modeling template in Arena, all level 3 processes of Source, Make, and Deliver are modeled to provide the SCS model builder a tool that is fast, follows the SCOR standards in processes and metrics, and simple to use. Here we report on the third version of the SCOR Template.
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| 10. |
- Sahlgren, Magnus, et al.
(författare)
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The Gavagai Living Lexicon
- 2016
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Ingår i: 10th edition of the Language Resources and Evaluation Conference, 23-28 May 2016, Portorož (Slovenia). - : ELRA.
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Konferensbidrag (refereegranskat)abstract
- This paper presents the Gavagai Living Lexicon, which is an online distributional semantic model currently available in 14 different languages. We describe the underlying distributional semantic model, and how we have solved some of the challenges in applying such a model to large amounts of streaming data. We also describe the architecture of our implementation, and discuss how we deal with continuous quality assurance of the lexicon.
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