Nanoporous metal films have many applications in a great variety of scientific fields, and especially nanoporous gold films have many applica- tions in green nanotechnology. Hence, structural and optical properties of such materials were investigated. Local density functions and local per- colation functions were calculated by using scaning electron micrographs and the optical properties of the films were calculated using the Hilfer equation. The results are presented in the report as graphs and show how the materials optical properties depend on the structure of the gold films.

In this thesis, wave propagation through acoustic materials with subwavelength slits structures is studied. Guided by the findings, acoustic wave focusing is achieved with a specific material design. By using a parameter retrieving method, an effective medium theory for a slab with periodic subwavelength cut-through slits is successfully derived. The theory is based on eigenfunction solutions to the acoustic wave equation. Numerical simulations are implemented by the finite-difference time-domain (FDTD) method for the two-dimensional acoustic wave equation. The theory provides the effective impedance and refractive index functions for the equivalent medium, which can reproduce the transmission and reflection spectral responses of the original structure. I analytically and numerically investigate both the validity and limitations of the theory, and the influences of material and geometry on the effective spectral responses are studied. Results show that large contrasts in impedance and density are conditions that validate the effective medium theory, and this approximation displays a better accuracy for a thick slab with narrow slits in it. Based on the effective medium theory developed, a design of a at slab with a snake shaped" subwavelength structure is proposed as a means of achieving acoustic focusing. The property of focusing is demonstrated by FDTD simulations. Good agreement is observed between the proposed structure and the equivalent lens pre- dicted by the theory, which leads to robust broadband focusing by a thin at slab.

Based on an ethnographic investigation, the dissertation examines the emergence and significance of discourses around “the environment” in the Lake District of the Araucanía region of Chile (Araucanía Lacustre). These are understood as part of the discursive aspect of globalization – the process by which the territory and its population are integrated ever more tightly into the networks of global market society – and considered in conjunction with discourses around Mapuche indigenous identity. Drawing on mediacultural studies, actor network theory, and medium theory, the analysis seeks to advance an ecological concept of communication that does not privilege human consciousness and agency. Communication is argued to be the principle by which space (physical and metaphysical) is configured and connected. Through a discussion of the physical and human geography of the territory it is argued that discourse is mutually immanent with material realities, including human practice and pre-discursive, nonhuman elements (chapter 3). The connection between environmental discourse and Mapuche culture is examined through the stereotype of the ecologically virtuous indigenous subject – a stereotype whose significance is changing as parallel neoliberal multicultural and sustainable development discourses boost the prestige of both Mapuche culture and ecological responsibility, even as the steady expansion of market society undermines both (Chapter 2). A program run by an NGO, funded by the Chilean state, and intended to market the agro-ecological produce of Mapuche small farmers to tourists, provides a concrete case of the intersection of neoliberal multiculturalism with environmental discourse (Chapter 4). The concept of “postmaterialism” is adapted, with a critical edge, in an exploration of the environmental activism and a certain dissatisfaction with modernity among college educated immigrants to the District from Santiago, North America and Europe (chapter 5). The process of globalization, through which Mapuche campesinos come to use environmentalist discourses, involves interactions among old and new information technologies, transportation technologies, and the nonanthropogenic realities of physical space-time and geography (chapter 6). The dissertation concludes with a normative argument about the ethical and epistemological inadequacy of globalizing market society.

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VO2-based films are thermochromic and exhibit high or low infrared transmittance when the temperature is below or above a critical temperature. The thermochromic switching is passive and reversible, and therefore VO2 based films are promising for energy-efficient window appli­cations. However the practicaluse of VO2 for energy-efficient windows has long been hampered by low luminous transmittance and low solar energy transmittance modulation. The main goal of this dissertation work is to address these issues. The first half of the work proposes the concept of nanothermochromics for simultaneous improvement of luminous transmittance and modulation of solar energy throughput. nanoth­ermochromics considers VO2 nanoparticle composite layers, whose optical properties were modeled by effective medium theories. Calculations on VO2 spheroids have shown that VO2 nanoparticles, especially nanospheres, can offer dramatically improved luminous transmittance and solar transmittance modulation that are not possible for films. Calculations done on coreshell nanoparticles showed comparable improvements and offer an opportunity to reduce the material costs. It was also found that the composite of In2O3:Sn (ITO) and VO2 can yield moderately high luminous transmittance, solar transmittance modulation and low-emittance properties. In the second half of the dissertation work, Mg-doped VO2 films were sputter deposited. Their band gaps and Mg-content were investigated by means of optical absorption measurement and Rutherford backscattering spectrometry, respectively. The band gaps of VO2 were found to increase by ∼3.9±0.5 eV per unit of atom ratio Mg/(Mg+V) for 0<Mg/(Mg+V)<0.21. Computations based on effective medium theory were done to estimate the performance of Mg­-doped VO2 films and nanoparticle composite layers. The results suggest that moderately doped VO2 films with 0<Mg/(Mg+V)<0.06 perform better than un-doped films and that the perfor­mance can be further enhanced with one layer of antireflection coating. The best results were achieved by un-doped VO2 nanospheres, closely followed by the VO2 nanospheres with low Mg-content. Furthermore, the an experimental study on sputter deposited VO2 nanorods has identified the geometry of the oxygen gas inlet, the type of substrate, the substrate temperature and the layer thickness as important factors that influence the growth morphology. Taken as a whole, nanothermochromics offered by VO2 nanoparticles was shown to be the best solution for VO2 based thermochromic energy-efficient window coatings.

AbstractTitle: Onlinegaming – A qualitative study of young people's attitudes about online gaming(Onlinespel – En Kvalitativ undersökning av Ungdomars attityder om onlinespel)Number of pages: 34 (35 including enclosures)Author: Armin MoradiTutor: Else NygrenCourse: Media and Communication Studies CPeriod: Autumn 2009University: Division of Media and Communication, Department of Information Science,Uppsala UniversityPurpose/Aim: The purpose of my thesis is that from a social perspective to examine and discussyoung people aged 16-18 vision of online gaming. Why online games are so popular and to see ifthe stereotype is a reality among young people in their late teens ..I also have a secondary purpose where I want to explore the social function of online games have,and what or what needs it fills in young people's everyday lives.Material/Method: The main method used in this essay has been qualitative group interviewswith 17 high school students. The result from these interviews has then been analysed usingseveral theories, Uses and gratification theory, Socialinteraction theory, Interactivity theory andmedium theory.Main results: The compilation of collected my results have shown that young people makeextensive use of online gaming pastime and to socialize with each other both virtually andphysically. Online gambling has on young people an entirely different meaning than it does forolder generations.For young people online is as natural as watching TV is for the oldergenerations.There are gender differences in perception of online games but it is not at all in the same highdegree as can be expected, the differences were minimal. The participants in my interviews havealso made an association exercise in which I presented as the words of 15-20 seconds to describeother words. Most replied to the word "Homework" that it was "boring" and the word "computergames" was the most frequently used word "fun".Keywords: Uses and gratification theory, Socialinteraction theory, Interactivity theory , Mediumtheory, Online gaming,

This dissertation includes the study of effective medium theories (EMTs) and their applications in describing wave propagation in anisotropic metamaterials, which can guide the design of metamaterials. An EMT based on field averaging is proposed to describe a peculiar anisotropic dispersion relation that is linear along the symmetry line but quadratic in the perpendicular direction. This dispersion relation is associated with the topological transition of the iso-frequency contours (IFCs), suggesting interesting wave propagation behaviors from beam shaping to beam splitting. In the framework of coherent potential approximation, an analytical EMT is further developed, with the ability to build a direct connection between the microscopic structure and the macroscopic material properties, which overcomes the requirement of prior knowledge of the field distributions. The derived EMT is valid beyond the long-wavelength limit. Using the EMT, an anisotropic zero-index metamaterial is designed. Moreover, the derived EMT imposes a condition that no scattered wave is generated in the ambient medium, which suggests the input signal cannot detect any object that might exist, making it invisible. Such correspondence between the EMT and the invisibilityinspires us to explore the wave cloaking in the same framework of coherent potential approximation. To further broaden the application realm of EMT, an EMT using the parameter retrieval method is studied in the regimes where the previously-developed EMTs are no longer accurate. Based on this study, in conjunction with the EMT mentioned above, a general scheme to realize coherent perfect absorption (CPA) in anisotropic metamaterials is proposed. As an exciting area in metamaterials, the field of metasurfaces has drawn great attention recently. As an easily attainable device, a grating may be the simplest version of metasurfaces. Here, an analytical EMT for gratings made of cylinders is developed by using the multiple scattering theory (MST) method and the lattice sum. Validation of the theory is verified by the agreement between the EMT predictions and the numerical calculations. It is found the EMT is capable of accurately predicting the wave transport behaviors, even for frequencies where the Mie resonances happen.

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Carbon nanotube forests are vertically grown tubular formations of graphene. Samples were grown with an injection chemical vapor deposition method on substrates of silicon with various deposited layers and bare fused silica. The morphology of the forest is characterized by the height, density, and presence of defects. Total diffuse reflectance and transmittance measurements were taken in the 2-16 �m spectral range and correlated to the forest’s specific morphology. From these correlations, the conditions necessary to maximize the absorption of the forest were found and exploited to cater sample growth for specific substrates to make ideal absorbers. From the transmittance data, the absorption coefficient is found via Beer-Lambert’s Law and also correlated to sample morphology, giving us an indication of the height of the forest needed for ideal absorption. Two models were used to attempt to reproduce the experimental absorption coefficient: an effective medium theory using a Maxwell Garnett approximation and by treating the carbon nanotube forest as an effective cylindrical waveguide with walls of graphite. Each model leads to a set of fitting parameters providing a better physical understanding of the forests. It was found that the effective medium theory gave results loosely corroborated with electron microscopy, but had trouble fitting the experimental data, and the index of refraction it provides does not behave like a unified medium. The waveguide model fits the data well, but it requires more experimental evidence to be more conclusive. The theoretical models need more work, but fabrication of ideal absorbers has been achieved on various substrates providing framework for their usage in radiometry and spectroscopy.

The purpose of this thesis is to present the different needs that can arise before VR use,and gratifications obtained by consumption. This includes finding out what media content users consume in VR, their motivations for why they consume the selectedcontent, how the choice of VR before other medium affects situations or interaction, and they feel after a session in virtual reality. The theories proven to provide a solid basis for answering the research questions are uses and gratifications theory, and medium theory. The collected empirical data is presented and analyzed within the frameworks ofthese theories, which together with previous research on virtual reality and VRheadsets, support the theoretical framework for this thesis. To gain in depth data of consumers motivations and own experiences, five semistructured qualitative interviewswhere conducted. The interviewees where asked various questions about their social and individual differences, gratifications sought and obtained, and their perception of how VR technology affects different situations and interaction. The collected empirical data is then presented and analyzed within the frameworks of uses and gratifications approach and medium theory. Results of the empirical data showed that the mostcommon needs to be satisfied by VR use are those of exersice, entertainment, practice, social interaction, and relaxation. Those needs are gratified by applications for exersice, entertainment applications, games, simulators, and social applications. The interviewees choose VR before other medium or real life activities because VR is more engaging than working out at home and less timeconsuming than leaving the house to exersice at the gym, more engaging and immersive than pc or console gaming for simulation games, and open in the sense of being able to walk up to strangers and socialize with in the virtual world. The study also showed that not only the technology hardware charachteristics, but also the software design found within the virtual environment, affects situations and interactions in a way that is perceived different and better than software found in other medium like social applications on the phone.