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Cell cultures provide researchers the opportunity to observe cell behavior in response to specific, well-defined environmental cues, leading to insights that enable better engineering design for tissue culture and other biomedical applications. Chemical and electrical stimuli have been successfully applied to cultured cells to approximate aspects of the dynamic conditions experienced in vivo. However, in vitro topographical cues have mostly been limited to static substrates that do not subject cells to the dynamic conditions they experience in vivo when tissue remodels during development and wound healing. Delivering dynamic topographical cues to cultured cells can answer long-standing questions about mechanisms of cell morphology changes. Such capabilities could also facilitate engineering of wound-healing matrices and nerve guidance conduits by promoting migration of cells and providing directional guidance to cellular processes. This dissertation describes the development of approaches for introducing in situ topographical cues to cell cultures and inducing responses such as neurite guidance and cell alignment. Both strategies undertaken in this work make use of multiphoton-promoted photochemistry to print and manipulate three-dimensional microscopic protein hydrogel structures. In one approach, a technique referred to as micro-3D printing, topographical guidance cues are printed in the proximity of cultured cells to guide the growth of cellular processes. By translating a tightly-focused pulsed laser beam through a printing reagent solution flooding cultured cells, features are printed that provide physical guidance to extending neurites from NG108-15 cells, a neuronal model cell type. In another approach, an innovative technique known as micro-3D imprinting is developed for producing micrometer-scale depressions on the surfaces of photoresponsive protein hydrogels. The impact of various experimental parameters on topographical feature dimensions is characterized. Micro-3D imprinting is used to introduce dynamic topographical changes on a cell culture substrate, demonstrating that NIH-3T3 cells, a fibroblast cell model, alter their morphology and alignment in response to the introduction of a grooved surface topography. This set of approaches introduces new tools to the repertoire of cell biologists for exploring the behavior of cells growing in a spatio-temporally dynamic environment, opening possibilities for studies of cellular behavior in conditions that may better reflect environments cells experience in vivo. / text

Above-surface interaction is a new and exciting topic in the field of human-computer interaction (HCI). It focuses on the design and evaluation of systems that humans can operate by moving their hands in the space above or in front of interactive displays. While many technologies emerge that make such systems possible, much research is still needed to make this interaction as natural and effortless as possible. First this thesis presents a set of guidelines for designing above-surface interactions, a collection of widgets that were designed based on these guidelines, and a system that can approximate the height of hands above a diffused surface illumination (DSI) device without any additional sensors. Then the thesis focuses on interaction techniques for activating graphical widgets located in this above-surface space. Finally, it presents a pair of studies that were conducted to investigate item selection in the space above a multitouch surface. The first study was conducted to elicit a set of gestures for above-table widget activation from a group of users. Several gestures were proposed by the designers to be compared with the user-generated gestures. The follow-up study was conducted to evaluate and compare these gestures based on their performance. The findings of these studies showed that there was no clear agreement on what gestures should be used to select objects in mid-air, and that performance was better when using gestures that were chosen less frequently, but predicted to be better by the designers, as opposed to those most frequently suggested by participants.

In dieser Arbeit wird die Erzeugung permanenter Nanostrukturen durch den Beschuss mit langsamen (v < 5x105m/s) hochgeladenen (q < 40) Ionen auf den Oberflächen der Ionenkristalle CaF2 sowie KBr untersucht. Die systematische Analyse der Probenoberfläche mittels Raster-Kraft-Mikroskopie liefert detaillierte Informationen über den Einfluss von potentieller und kinetischer Projektilenergie auf den Prozess der Strukturerzeugung. Der individuelle Einfall hochgeladener Ionen auf der KBr(001)-Oberfläche kann die Erzeugung monoatomar tiefer, lochartiger Strukturen -Nanopits- mit einer lateralen Ausdehnung von wenigen 10nm initiieren. Das Volumen dieser Löcher und damit die Anzahl gesputterter Sekundärteilchen zeigt eine lineare Abhängigkeit von der potentiellen Energie der Projektile. Für das Einsetzen der Locherzeugung konnte ein von der Projektilgeschwindigkeit abhängiger Grenzwert der potentiellen Energie E_grenz^pot (Ekin) gefunden werden. Auf der Basis der defekt-induzierten Desorption durch Elektronen wurde unter Einbeziehung von Effekten der Defektagglomeration ein konsistentes mikroskopisches Modell für den Prozess der Locherzeugung konzipiert. Für die CaF2(111)-Oberfläche kann die aus jüngsten Studien bekannte, individuelle Erzeugung hügelartiger Nanostrukturen -Nanohillocks- durch hochgeladene Ionen in dieser Arbeit auch für kleinste kinetische Energien (E_kin < 150eVxq) verifiziert werden. Die potentielle Energie der einfallenden Ionen wird damit erstmalig zweifelsfrei als alleinige Ursache der Nanostrukturerzeugung identifiziert. Zudem zeigt sich bei geringer Projektilgeschwindigkeit eine Verschiebung der potentiellen Grenzenergie zur Hillock-Erzeugung. Im Rahmen einer Kooperation an der Technischen Universität Wien durchgeführte Simulationsrechnungen auf der Grundlage des inelastischen thermal spike-Modells zeigen, dass die individuelle Hillock-Erzeugung durch hochgeladene Ionen mit einer lokalen Schmelze des Ionenkristalls verknüpft werden kann. Dem essentiellen Einfluss der Elektronenemission während der Wechselwirkung des hochgeladenen Ions mit der Oberfläche auf den Prozess der Nanostrukturerzeugung wird in komplementären Untersuchungen zur Sekundärelektronenstatistik Rechnung getragen. Erstmalig werden dabei Gesamtelektronenausbeuten für Isolatoroberflächen bei kleinsten Projektilgeschwindigkeiten (v < 1x10^5 m/s) bestimmt. Für Geschwindigkeiten v < 5x10^4 m/s findet sich für die Isolatoroberfläche in starkem Kontrast zu Metallen ein signifikanter Abfall der Elektronenausbeute mit sinkender kinetischer Energie. Mögliche Ursachen dieses Effektes werden auf der Grundlage unterschiedlicher Modelle diskutiert.

Algae are photosynthetic microorganisms that convert carbon dioxide and sunlight into biomass that can be used for biofuel production. Although they are usually cultivated in suspension, these microorganisms are capable of forming productive biofilms over substrata given the right conditions. This dissertation focuses on algal biofilms and their application in biofuel feedstock production. In particular it reports the construction and performance of an algae biofilm photobioreactor, the physico-chemical surface properties of different algal species and adhesion substrata, and cell-surface interactions based on experimental results and theoretical models. A novel algae biofilm photobioreactor was constructed and operated (i) to demonstrate the proof of concept, (ii) to analyze the performance of the system, and (iii) to determine the key advantages and short comings for further research. The results indicated that significant reductions in water and energy requirements were possible with the biofilm photobioreactor. Although the system achieved net energy ratio of about 6, the overall productivity was low as Botryococcus branunii is notoriously slow growing algae. Thus, further studies were focused on identification of algal species capable of biofilm growth with larger biomass and lipid productivities. Adhesion of cells to substrata precedes the formation of all biofilms. A comprehensive study has been conducted to determine the interactions of a planktonic and a benthic algal species with hydrophilic and hydrophobic substrata. The physico-chemical surface properties of the algal cells and substrata were determined and using these data, cell-substrata interactions were modeled with the thermodynamic, Derjaguin, Landau Verwey, Overbeek (DLVO) and Extended Derjaguin, Landau, Verwey, Overbeek (XDLVO) approaches and critical parameters for algal adhesion were identified. Finally, the adhesion rate and strength of algal species were quantified with parallel plate flow chamber experiments. The results indicated that both cell and substrata surface hydrophobicity played a critical role for the adhesion rate and strength of the cells and XDLVO approach was the most accurate model. Finally, based on these findings the physico-chemical surface properties of ten algal species and six substrata were quantified and a screening was done to determine algae species substratum couples favoring adhesion and biofilm formation. / text

The scattering of H2 from Si(100) has been studied using pulsed molecular beam techniques and quantum state-specific detection methods. These studies can be used to test theoretical calculations and give insight into new theories of molecule-surface interactions, a fundamental study in a diverse field of science and technology. In this work, time-of-flight (TOF) spectra of the elastic scattering of H2(v=1. J=1) and H2(v=0, J=1) from clean Si were recorded over a wide range of surface temperatures. Two data processing strategies were developed to extract rich kinematic information from the scattering experiments, e.g., mean translational energy exchange, absolutely survival probability, and angular and speed distribution of the scattered molecules. No such set of quantitative results has been reported before for this system. Compared with close packed metal surfaces, these scattering experiments from a covalently bonded semiconductor surface showed a completely distinct dynamics, e.g. the finding of energy gain instead of loss from the substrate, much broader angular distribution and some counterintuitive surface temperature effects. From the studies of molecules/surface scattering experiments, the thermal excitation on Si(100) surface which depends on surface temperature can substantially alter the adsorption barrier and its distribution, and therefore changes the kinematics of scattered molecules. As a result, even the most basic understanding of the dynamics has to include phonon excitation and deexcitation of the silicon substrate. / text

Den här doktorsavhandlingen presenterar ytinteraktion som ett gränssnitts-paradigm för grafiska användargränssnitt inom kreativa tillämpningar. Ytinteraktion utgår ifrån användarnas innehåll och allt innehåll presenteras på en oändligt stor tvådimensionell yta. Ytan är gränssnittet mot en databas som navigeras och zoom, pan och textfilter. Textfilter används för att visa vilka innehållselement som motsvarar en textsträng, ju fler tecken i strängen, desto färre motsvarande element. Ytinteraktion gör att användare kan dela och redigera innehåll tillsammans via synkront samarbete.Ytinteraktion har studerats genom att utveckla en interaktiv prototyp för kollaborativ live multimedia. Prototypen designades tillsammans med musik- och videoartister inom electronica- och klubbmusikgenren. Den kan användas med pekskärm eller med skäm, mus och tangentbord. Design-processens resultat utvärderades genom en fallstudie som omfattade artisternas förberedelse inför och genomförandet av ett framträdande vid en festival. Analysen av data resulterade i fem bruksvärden; instrumentvärde, kommunikationsvärde, förberedelsevärde, livevärde och underhållningsvärde. Det huvudsakliga bruksvärdet var att den interaktiva prototypen uppfattades som ett instrument. Prototypens design underlättade kommunikationen mellan artisterna i flykten på scen. Instrumentvärdet gjorde det lättare att spela live vilket i sin tur medförde att publiken blev underhållen. Kunskap om den interaktiva prototypen och ytinteraktion har formats med forskning genom design där aktionsforskning var det övergripande ramverket i forskningsprocessen. Aktionsforskning är ett kvalitativ förhållningssätt som sätter fokus på praktikers deltagande i forskningsprocessen och att forskningen intervenerar i praktiken med syfte att förbättra den och att inducera kunskap. Som ett resultat av designprocessen presenteras designprinciper för ytinteraktion. Dessa gör resultaten användbara för praktiker inom interaktionsdesign, människa–datorinteraktion och programvaruteknik. / This dissertation presents surface interaction as an interface paradigm for graphical user interfaces of creative applications. The users' content is the basis for surface interaction, and all content is presented on an infinitely large two-dimensional surface. The surface is an interface to a database, and is navigated by zoom, pan, and text filter. Text filter is to display which content elements match a text string, the more characters of the string the less matching element. Surface interaction allows users to share and edit content collaboratively via synchronous collaboration. Surface interaction was examined by developing an interactive prototype for collaborative live multimedia. The prototype was designed in collaboration with music and video artists within the genres of electronica and club music. It can be used either with a touch screen or with a monitor, mouse, and keyboard. The result of the design process was evaluated in a case study which included the artists' preparations for and carrying through of  a live performance at a festival. The analysis of data yielded five utility values; instrument value, communication value, preparation value, live value, and entertainment value. The main utility value of the interactive prototype was that the artists saw it as instrument.  The design of the prototype made communication easier in the live situation on stage. The instrument value made it easier to play live which consequently entertained the audience.Cognition in the interactive prototype and surface interaction has been created with research through design where action research was the overarching framework. Action research is a qualitative method  which focuses on the participating practitioners and on the intervention of the practice with the purpose improving the practitioner’s situation and of increasing the knowledge of the participants. Design principals and guidelines will be presented as a result of the design process. The guidelines make the results of this dissertation applicable to practitioners of interaction design, human computer interaction and software engineering.

Above-surface interaction is a new and exciting topic in the field of human-computer interaction (HCI). It focuses on the design and evaluation of systems that humans can operate by moving their hands in the space above or in front of interactive displays. While many technologies emerge that make such systems possible, much research is still needed to make this interaction as natural and effortless as possible. First this thesis presents a set of guidelines for designing above-surface interactions, a collection of widgets that were designed based on these guidelines, and a system that can approximate the height of hands above a diffused surface illumination (DSI) device without any additional sensors. Then the thesis focuses on interaction techniques for activating graphical widgets located in this above-surface space. Finally, it presents a pair of studies that were conducted to investigate item selection in the space above a multitouch surface. The first study was conducted to elicit a set of gestures for above-table widget activation from a group of users. Several gestures were proposed by the designers to be compared with the user-generated gestures. The follow-up study was conducted to evaluate and compare these gestures based on their performance. The findings of these studies showed that there was no clear agreement on what gestures should be used to select objects in mid-air, and that performance was better when using gestures that were chosen less frequently, but predicted to be better by the designers, as opposed to those most frequently suggested by participants.