| 21. |
- Johansson Fernstad, Sara, 1980-
(författare)
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Algorithmically Guided Information Visualization : Explorative Approaches for High Dimensional, Mixed and Categorical Data
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Facilitated by the technological advances of the last decades, increasing amounts of complex data are being collected within fields such as biology, chemistry and social sciences. The major challenge today is not to gather data, but to extract useful information and gain insights from it. Information visualization provides methods for visual analysis of complex data but, as the amounts of gathered data increase, the challenges of visual analysis become more complex.This thesis presents work utilizing algorithmically extracted patterns as guidance during interactive data exploration processes, employing information visualization techniques. It provides efficient analysis by taking advantage of fast pattern identification techniques as well as making use of the domain expertise of the analyst. In particular, the presented research is concerned with the issues of analysing categorical data, where the values are names without any inherent order or distance; mixed data, including a combination of categorical and numerical data; and high dimensional data, including hundreds or even thousands of variables.The contributions of the thesis include a quantification method, assigning numerical values to categorical data, which utilizes an automated method to define category similarities based on underlying data structures, and integrates relationships within numerical variables into the quantification when dealing with mixed data sets. The quantification is incorporated in an interactive analysis pipeline where it provides suggestions for numerical representations, which may interactively be adjusted by the analyst. The interactive quantification enables exploration using commonly available visualization methods for numerical data. Within the context of categorical data analysis, this thesis also contributes the first user study evaluating the performance of what are currently the two main visualization approaches for categorical data analysis.Furthermore, this thesis contributes two dimensionality reduction approaches, which aim at preserving structure while reducing dimensionality, and provide flexible and user-controlled dimensionality reduction. Through algorithmic quality metric analysis, where each metric represents a structure of interest, potentially interesting variables are extracted from the high dimensional data. The automatically identified structures are visually displayed, using various visualization methods, and act as guidance in the selection of interesting variable subsets for further analysis. The visual representations furthermore provide overview of structures within the high dimensional data set and may, through this, aid in focusing subsequent analysis, as well as enabling interactive exploration of the full high dimensional data set and selected variable subsets. The thesis also contributes the application of algorithmically guided approaches for high dimensional data exploration in the rapidly growing field of microbiology, through the design and development of a quality-guided interactive system in collaboration with microbiologists.
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| 22. |
- Johansson, Kenth S., et al.
(författare)
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Surface modification of wheat gluten films for improved water resistance
- 2010
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Ingår i: Abstracts of Papers of the American Chemical Society. - : American Chemical Society (ACS). - 0065-7727. ; 240
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Renewable packaging materials are of interest for a more sustainable environment, and wheat gluten (WG) is one of the most interesting candidates to replace petroleum-based oxygen-barrier polymers for packaging applications. This is due to its attractive combination of flexibility and strength, high gas (especially O2) barrier properties under low humidity conditions and renewability. The main drawback of WG, as with most biopolymers, is its water and moisture sensitivity. The aim of this study was therefore to improve the hydrophobicity of WG films by means of surface modification while maintaining the excellent O2 barrier properties. The surface modification work included a combination of electrospinning of WG fibers and different plasma surface modifications. The latter involved He plasma treatment for crosslinking the WG film prior to the deposition of electrospun WG fibers, O2/Ar plasma etching of the WG films with and without electrospun WG fibers for increasing the surface roughness, and plasma polymerization of hexamethyldisiloxane (HMDSO) and other hydrophobic precursors for hydrophobicity. The plasma polymerization trials were performed both at reduced and atmospheric pressure conditions. The aim of the combined work was to maximize the hydrophobicity by combining a suitable nano-microstructure of the WG fibers with the hydrophobicity of the plasma-deposited coatings. The surface modification work was mainly evaluated by means of water contact angle measurements (hydrophobicity), Scanning Electron Microscopy (surface structures), Water Vapor Transmission Rate (WVTR) (moisture barrier) and Oxygen Transmission Rate (OTR) measurements (oxygen barrier). The surface modification work resulted in significantly improved hydrophobic properties of the WG films. The initial water contact angle increased from 65 to 110-130 degrees, depending on the combinations of electrospinning and plasma modification conditions. The plasma coatings prepared at ambient conditions resulted in slightly lower contact angles compared the plasma coating prepared at reduced pressure. The WVTR and OTR measurements are still in progress and will be reported at the meeting.
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| 23. |
- Johansson, Linda, et al.
(författare)
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Temperature and trapping characterization of an acoustic trap with miniaturized integrated transducers - towards in-trap temperature regulation
- 2013
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Ingår i: Ultrasonics. - : Elsevier BV. - 0041-624X .- 1874-9968. ; 53:5, s. 1020-1032
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Tidskriftsartikel (refereegranskat)abstract
- An acoustic trap with miniaturized integrated transducers (MITs) for applications in non-contact trapping of cells or particles in a microfluidic channel was characterized by measuring the temperature increase and trapping strength. The fluid temperature was measured by the fluorescent response of Rhodamine B in the microchannel. The trapping strength was measured by the area of a trapped particle cluster counter-balanced by the hydrodynamic force. One of the main objectives was to obtain quantitative values of the temperature in the fluidic channel to ensure safe handling of cells and proteins. Another objective was to evaluate the trapping-to-temperature efficiency for the trap as a function of drive frequency. Thirdly, trapping-to-temperature efficiency data enables identifying frequencies and voltage values to use for in-trap temperature regulation. It is envisioned that operation with only in-trap temperature regulation enables the realization of small, simple and fast temperature-controlled trap systems. The significance of potential gradients at the trap edges due to the finite size of the miniaturized transducers for the operation was emphasized and expressed analytically. The influence of the acoustic near field was evaluated in FEM-simulation and compared with a more ideal 1D standing wave. The working principle of the trap was examined by comparing measurements of impedance, temperature increase and trapping strength with impedance transfer calculations of fluid-reflector resonances and frequencies of high reflectance at the fluid-reflector boundary. The temperature increase was found to be moderate, 7 degrees C for a high trapping strength, at a fluid flow of 0.5 mm s(-1) for the optimal driving frequency. A fast temperature response with a fall time of 8 s and a rise time of 11 s was observed. The results emphasize the importance of selecting the proper drive frequency for long term handling of cells, as opposed to the more pragmatic way of selecting the frequency of the highest acoustic output. Trapping was demonstrated in a large interval between 9 and 11.5 MHz, while the main trapping peak displayed FWHM of 0.5 MHz. A large bandwidth enables a more robust manufacturing and operation while allowing the trapping platform to be used in applications where the fluid wavelength varies due to external variations in fluid temperature, density and pressure.
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| 24. |
- Johansson, Mikael, 1975, et al.
(författare)
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From BIM to VR - Integrating immersive visualizations in the current design process
- 2014
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Ingår i: Proceedings of the International Conference on Education and Research in Computer Aided Architectural Design in Europe. - 2684-1843. ; 2, s. 261-269
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Konferensbidrag (refereegranskat)abstract
- This paper presents a system that allows immersive visualizations to become a natural and integrated part of the current building design process. It is realized through three main components: (1) the Oculus Rift - a new type of Head Mounted Display (HMD) directed at the consumer market, (2) a real-time rendering engine supporting large Building Information Models (BIM) that is, (3) implemented as a plug-in in a BIM authoring software. In addition to provide details regarding the implementation and integration of the different components in our system, we present an evaluation of it from three different perspectives; rendering performance, navigation interface and the ability to support fast design iterations.
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| 25. |
- Johansson, Roger, et al.
(författare)
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Eye movements play an active role when visuospatial information is recalled from memory
- 2012
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Ingår i: Journal of Vision. ; 12:9
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Konferensbidrag (refereegranskat)abstract
- Abstract in Undetermined Whilst it has been established that spontaneous eye movements occur with visual imagery and that they are comparable with those from an original scene inspection (e.g., Brandt & Stark, 1997; Johansson, Holsanova, & Holmqvist, 2006), the exact purpose of these eye movements has been a hot topic of debate (cf., Ferreira et al., 2008; Richardson et al., 2009). Do they have an active and functional role in memory retrieval or are they merely an epiphenomenon? In a recent study we reported that when eye movements were prohibited for participants who orally described pictures from memory, their recollections became altered and impaired (Johansson, Holsanova, Dewhurst, & Holmqvist, (in press). Journal of Experimental Psychology: Human Perception and Performance). The current study was designed as a follow-up, aiming to uncover exactly how imposing different eye movements on participants affects memory retrieval processes. Eye movements were recorded from participants who recalled properties and spatial arrangements of sets of objects under four different manipulations: (1) free viewing on a blank screen; (2) gazing at a fixation cross; (3) looking at an area which was matched with the original locations of the objects to be recalled; (4) looking at an area which did not match the original locations of the objects to be recalled. By restricting eye movements in different ways during recall, we demonstrate the sensitivity of retrieval performance to specific eye movement manipulations. Results provide evidence that eye movements do have an active and supportive role when visuospatial information is recalled by highlighting the circumstances under which a visual memory is hampered. Additionally, findings suggest that the influence of "eye movements to nothing" is primarily related to the processing and retrieval of spatial information.
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| 26. |
- Johansson, Roger, et al.
(författare)
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Look Here, Eye Movements Play a Functional Role in Memory Retrieval.
- 2014
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Ingår i: Psychological Science. - : SAGE Publications. - 0956-7976 .- 1467-9280. ; 25:1, s. 236-242
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Tidskriftsartikel (refereegranskat)abstract
- Research on episodic memory has established that spontaneous eye movements occur to spaces associated with retrieved information even if those spaces are blank at the time of retrieval. Although it has been claimed that such looks to "nothing" can function as facilitatory retrieval cues, there is currently no conclusive evidence for such an effect. In the present study, we addressed this fundamental issue using four direct eye manipulations in the retrieval phase of an episodic memory task: (a) free viewing on a blank screen, (b) maintaining central fixation, (c) looking inside a square congruent with the location of the to-be-recalled objects, and (d) looking inside a square incongruent with the location of the to-be-recalled objects. Our results provide novel evidence of an active and facilitatory role of gaze position during memory retrieval and demonstrate that memory for the spatial relationship between objects is more readily affected than memory for intrinsic object features.
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| 27. |
- Johansson, Viktoria, et al.
(författare)
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Microscopic Particles in Two Fractions of Fresh Cerebrospinal Fluid in Twins with Schizophrenia or Bipolar Disorder and in Healthy Controls
- 2012
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 7:9
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Tidskriftsartikel (refereegranskat)abstract
- Background: Using scanning electron microscopy, microscopic structures have been identified in fresh cerebrospinal fluid (CSF) in patients with schizophrenia and bipolar disorder, but only rarely in control subjects. However, it has not been determined whether these microscopic particles represent state or trait markers, i.e. if their presence is related to clinical manifestations of the disease or if they also can be found in as yet asymptomatic individuals with a genetic liability. This question can be addressed by studying twins discordant or concordant for schizophrenia or bipolar disorder. Methodology/Principal Findings: We investigated microscopic structures in CSF in 102 individuals: 21 monozygotic and 16 dizygotic twins affected or not affected with schizophrenia, schizoaffective disorder or bipolar disorder and in 65 healthy singleton controls. A first and a second fraction of CSF was freshly applied on filters and examined by scanning electron microscopy technique. Spherical particles with lipid appearance averaging between 0.1 to 8.0 mu m in diameter were detected in the center of the filter as well as located in the margins of larger aggregates binding in a viscous state. Structures were found in 12 of 17 probands, 5 of 12 healthy co-twins and 3 of 73 healthy controls. Thus, a positive microscopic finding significantly increased the likelihood of belonging to the proband group (OR = 48, 95% CL: 8.2-550, p<0.0001) and the co-twin-group (OR = 16, 95% CL: 2.0-218, p = 0.006). Age, sex, history of alcohol abuse or anxiety syndrome, somatic disorder and markers of acute inflammatory activity did not account for group differences; nor did exposure to psychotropic medication. Conclusion: Presence of microscopic particles in CSF may possibly reflect trait dependent genetic or environmental vulnerability in patients with schizophrenia, schizoaffective disorder or bipolar disorder.
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| 28. |
- Johansson, Victoria, et al.
(författare)
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Språk och hjärna
- 2013
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Ingår i: Språket, människan och världen : människans språk 1-2. - 9789144083391 ; , s. 225-241
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Bokkapitel (populärvet., debatt m.m.)
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| 29. |
- Johansson, Victoria, et al.
(författare)
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Språk och hjärna
- 2013
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Ingår i: Språket, människan och världen. - Lund : Studentlitteratur AB.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 30. |
- Khosravi, Sara
(författare)
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Protein-Based Adhesives for Particleboards
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of this study was to elucidate the possibilities to use wheat gluten (WG) as a binder for particleboards, as well as soy protein isolate (SPI). The focus was on the effect of the adhesive formulation and the processing conditions, while the press parameters were kept constant. Some aspects of the dispersion and the preparation of the dispersions that were investigated are: the time (1, 3 or 5h) to prepare the dispersion, the temperature (room temperature, 50 or 80°C) during the preparation of the dispersions and the effect of storing (1, 2.5 or 4 days) the dispersions. Furthermore, the utilization of green particles versus dried particles was examined. The concentration (12, 16, 20 or 24%) of WG dispersion and the process for applying it to the particles was studied. Two application methods were evaluated, in application method 1 (appl. 1) all the dispersion was added to the particles in one step before the particles were dried. When application method 2 (appl. 2) was employed the dispersion was added in two steps, some of the dispersion was added before the drying and some after the drying. The considered board properties were internal bond (IB), thickness swelling (TS) and water absorption (ABS). The results show that in the case of SPI dispersion the temperature seems to not be of significant importance and it appears as if longer time to prepare the dispersion is beneficial. On the other hand for WG dispersion it looks as if a lower temperature is preferable for the preparation of the dispersion and that the time to prepare the dispersion is of no importance. Furthermore, storing the dispersions for more than one day before it was used as an adhesive for particleboards (PB) resulted in poorer boards. According to this study it is beneficial to use dried particles instead of green particles. Additionally, the results show that the interaction between the concentration of WG dispersion and how it is applied is a significant factor, considering the IB value. However, in general the two step process (appl. 2) is preferable.
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