Дисертації з теми "Interaction and exchange"

For a physical space to have an emotional impact on those who experience it, we must consider the connection and relationship between objects and experience, and how people make individual connections to insentient places. It is this symbiotic relationship that allows a building or space to attain a “soul”. Through the adaptive re-use of a Richmond, Virginia building, this thesis project explores strategies of staging physical interaction and organic experiences through art and culture in the context of a mixed-use niche hotel.

The Golgi apparatus is the main crossroad of the intracellular trafficking network in all eukaryotic cells and plays a crucial role in the distribution of cellular material. To ensure the proper sorting and delivery of cargo proteins to their destination while maintaining Golgi homeostasis the coordination of all transport events to and from this organelle is required. Although a cascade of activation events has already been reported for Golgi Ypt/Rab proteins that function in the exocytic pathway, their connection to incoming vesicles from endosomal compartments or to the different Arf mediated vesicle formation machineries has still to be established. In addition, the role of lipids and the interplay between lipid and protein regulators at the Golgi are largely missing. In the present study, we used several approaches to unravel the crosstalk between known regulators of Golgi trafficking and to identify new proteins involved in this process. As starting point, we considered the results from four different screens before focusing on the role of Arf exchange factors. We report two new physical interactors of the late Golgi Arf-GEF Sec7p: the lipid kinase Pik1p and the cyclic nucleotide phosphodiesterase Cpd1p. In addition, our studies on the function of Sec7p revealed additional feature of this protein and it’s relationship to the other yeast Golgi Arf-GEFs. Arf proteins and their regulators play an important role in the formation of vesicles at the exit from the Golgi apparatus. There are three Golgi-localized Arf-GEFs in S.cerevisiae, Sec7p and the redundant Gea1p/Gea2p. While it has been established that Sec7p function does not overlap with the Gea’s, the specific role of these proteins remains unclear. We show that Sec7p colocalizes poorly with the Gea’s, indicating that these proteins activate Arf on different Golgi sub-compartments. In addition, our data suggest that Sec7p mainly promotes the formation of post-Golgi transport vesicles supporting forward transport from the late Golgi while the Gea’s primarily regulate COPI-mediated retrograde traffic. This observation is consistent with published data from mammalian cells and suggests that the spatial and temporal regulation of Arf is conserved from yeast to mammals. Both Arf regulation and phosphatidylinositol 4-phosphate (PI4P) metabolism are important factors for Golgi function. Here, we show that the yeast PI4-kinase, Pik1p binds specifically to Sec7p but not Gea1p or Gea2p. Taken together, the physical interaction, the colocalization and similar transport phenotypes of the respective mutants suggests a functional link between Pik1p and Sec7p but not the Gea’s. In addition, Pik1p binds to the catalytic domain of Sec7p and could directly influence the activity of the GEF. We propose that this interaction coordinates Arf activation with PI4P production to generate a highly specific dual recognition system for the recruitment of specific effectors to the late Golgi. Besides its catalytic domain, Sec7p shares several conserved regions with other members of the BIG/GBF Arf-GEF subfamilies, including the N-terminal DCB (Dimerization/Cyclophilin Binding) domain. We show that a single point mutation in the DCB domain of Sec7p efficiently inhibits Arf activation without affecting membrane recruitment of the GEF and could interfere with a possible dimerization of the protein. We identified Cpd1p as an allele specific dosage suppressor of the Sec7p DCB domain mutation. Cpd1p and Sec7p physically interact and both proteins localize independently to the late Golgi. Increased Golgi level of Cpd1p compensates for the loss of interaction due to the mutation in the DCB domain of Sec7p. The catalytic activity of Cpd1p is important for the rescue, indicating an intriguing connection between the Arf activation cycle and ADP-ribose derivates. We also find that Cpd1p interacts with several other proteins involved in Golgi- and post-Golgi transport events. Hence, Cpd1p is a new regulator of vesicular traffic at the Golgi that could act as a scaffolding factor for Sec7p and other transport proteins.

This doctoral thesis aims to contribute to the interaction between exchange rates and stock prices at firm level, using a large unbalanced panel consisting UK non-financial companies over the period 1990—2011. There are six chapters. After the Introduction, Chapter 2 critically and comprehensively reviews previous theoretical and empirical studies of the relationship between exchange rates and stock prices, and then suggests several new research ideas. Chapter 3 derived a theoretical framework for the transmission channels through which changes in exchange rates pass-though into stock prices. The model is then calibrated to provide implications. Two main transmission channels are identified: the revenue-side channel and the cost side channel. The findings show that the effect through the revenue-side channel can explain more than 80% of currency exposures, while less than 20% can be explained by impact through the cost-side. Chapter 4 develops an empirical model to provide evidence for the theoretical framework in Chapter 3. Meanwhile, this chapter also examines how firms’ characteristics have an impact on identified transmission mechanism. Chapter 5 distinguishes the unanticipated parts of exchange rate variations from the anticipated ones, using more advanced return decomposition techniques and VAR specifications. To be specific, foreign exchange beta is decomposed into foreign exchange beta due to unanticipated changes in cash flows and discounted rates. The key findings, contributions and limitations are given in Chapter 6, as well as new research ideas for the future.

The aim of this thesis is to analyse theTelationship between the exchange rate and stockmarket, in the UK, USA, Germany, Japan, Canada and the Netherlands over the period 1974 to 1994. It is motivated by recent changes in the international financial environment, particularly the gradual removal of exchange restrictions and the consequent rise in capital flows between the main economies. A further motivation has been the increasing use of stock market variables in macroeconomic models. The theoretical literature indicates that for a variety of different exchange rate models, it is possible for the exchange rate and stock market to interact in a number of different ways, following an exogenous shock. It is therefore pnmanly an empirical question as to the specific signs on the variables in the models analysed. This thesis predominantly uses cointegration and error correction models, so that both the long run relationship and short run dynamics can be examined separately. The thesis shows that stock prices and exchange rates do not have common trends, but do have common cycles. In general exchange rates and stock prices are found to be inversely related. In addition the foreign exchange market risk premium is shown to be directly linked to the differential between the domestic and foreign equity risk premiums. It is also found that the expected change in the exchange rate is more closely linked to risk rather than return differentials.

Semiconductor quantum dot systems offer a promising platform for quantum computation. And these quantum computation candidates are normally based on spin or charge properties of electrons. In these systems, we focus on quantum computation based on electron spins since these systems has good scalability, long coherence times, and rapid gate operations. And this thesis focuses on building a theoretical description of quantum dot systems and the link between theory and experiments. In many quantum dot systems, exchange interactions are the primary mechanism used to control spins and generate entanglement. And exchange energies are normally positive, which limits control flexibility. However, recent experiments show that negative exchange interactions can arise in a linear three-dot system when a two-electron double quantum dot is exchange coupled to a larger quantum dot containing on the order of one hundred electrons. The origin of this negative exchange can be traced to the larger quantum dot exhibiting a spin triplet-like rather than singlet-like ground state. Here we show using a microscopic model based on the configuration interaction (CI) method that both triplet-like and singlet-like ground states are realized depending on the number of electrons. In the case of only four electrons, a full CI calculation reveals that triplet-like ground states occur for sufficiently large dots. These results hold for symmetric and asymmetric quantum dots in both Si and GaAs, showing that negative exchange interactions are robust in few-electron double quantum dots and do not require large numbers of electrons. Recent experiments also show the potential to utilize large quantum dots to mediate superexchange interaction and generate entanglement between distant spins. This opens up a possible mechanism for selectively coupling pairs of remote spins in a larger network of quantum dots. Taking advantage of this opportunity requires a deeper understanding of how to control superexchange interactions in these systems. Here, we consider a triple-dot system arranged in linear and triangular geometries. We use CI calculations to investigate the interplay of superexchange and nearest-neighbor exchange interactions as the location, detuning, and electron number of the mediating dot are varied. We show that superexchange processes strongly enhance and increase the range of the net spin-spin exchange as the dots approach a linear configuration. Furthermore, we show that the strength of the exchange interaction depends sensitively on the number of electrons in the mediator. Our results can be used as a guide to assist further experimental efforts towards scaling up to larger, two-dimensional quantum dot arrays.
Doctor of Philosophy
Semiconductor quantum dot systems offer a promising platform for quantum computation. And these quantum computation candidates are normally based on spin or charge properties of electrons. In these systems, we focus on quantum computation based on electron spins since these systems has good scalability, long coherence times, and rapid gate operations. And this thesis focuses on building a theoretical description of quantum dot systems and the link between theory and experiments. A key requirement for quantum computation is the ability to control individual qubits and couple them together to create entanglement. In quantum dot spin qubit systems, the exchange interaction is the primary mechanism used to accomplish these tasks. This thesis is about attaining a better understanding of exchange interactions in quantum dot spin qubit systems and how they can be manipulated by changing the configuration of the system and the number of electrons. In this thesis, we show negative exchange energy can arise in large size quantum dots. This result holds for symmetric and asymmetric shape of the large dots. And we also provide a quantitative analysis of how large quantum dots can be used to create long-distance spin-spin interactions. This capability would greatly increase the flexibility in designing quantum processors built by quantum dot spins. The interplay of these systems with different geometry can serve as a guide to assist further experiments and may hopefully be the basis to build two-dimensional quantum dot arrays.

This thesis examines the relationship between exchange rate changes and stock returns, focusing on six Middle East and North African emerging markets: Egypt, Kuwait, Morocco, Oman, Saudi Arabia and Turkey. The aforementioned relationship is explored at different levels of aggregation for the stock market (from country to finn level). Three papers are presented in this thesis. The first paper considers the linkage between stock prices and exchange rates in four Middle East emerging markets. In contrast to the existing evidence that uses a global market index to uncover such a relationship I find that for my sample countries oil prices emerge as the dominant factor in the above relationship. I consider the presence of regime shifts and I find evidence of cointegration only'for the period following the 1999 oil price shock. Readjustment towards equilibrium in each stock market occurs via oil price changes. Finally, I perfonn a number of robustness checks and produce persistence profiles. In the second paper, I examine the presence of volatility spillovers between nominal exchange rates and stock returns in three MENA countries: Egypt, 'Morocco and Turkey. The multivariate GARCH model which I use does not produce evidence of cross-market effects for the general stock indices returns. Nevertheless, bidirectional shock and volatility spillovers between exchange rates and sector stock returns exist at the industry sector level. Those findings are more pronounced in Egypt and Turkey. The different results are due to the different exchange rate regimes/policies adopted by the three countries. While exchange rates in Egypt and Turkey were allowed to float, Morocco followed a more tightly managed exchange rate regime. The third paper tests for the impact of announcing floating and devaluating the exchange rate on stock returns in three MENA countries namely, Egypt, Morocco and Turkey_ I, first, use the event study methodology put forward by Hilliard and Savickas (2002), testing for eventinduced, abnonnal volatility in the stock returns. I, then, use three different methodologies to testfor abnonnal returns. These are, first, the approach given by Brown and Warner (1980), and the remaining two, which control for event induced volatility, are based upon the study of Boehmer. Musumeci and Poulsen (1991), and upon the method fonnulated by Savickas (2003). I find clear evidences of abnonnal volatility and abnonnal return due to this event in Egypt and Turkey. but I could not find such evidence in Morocco

This thesis presents the optical characterization of interfacial exchange coupling interaction in ferromagnetic bilayer heterostructures. Both static and dynamic magnetic response are investigated in the exchange-coupled Co2FeAl/(Ga,Mn)As bilayer system using static magneto-optical Kerr effect (MOKE) and time-resolved magneto optical Kerr effect (TRMOKE) techniques. The goal of this thesis is to understand the underlying physics of the interfacial exchange coupling effect on the ultrafast spin dynamics in a ferromagnetic metal/ferromagnetic semiconductor bilayer heterostructure. Our finding provides a viable pathway for designing advanced semiconductor spintronic devices for ultrafast low-power spin manipulation. First, a significant enhancement of the excitation efficiency of coherent magnetization precession is observed in the ferromagnetically exchangecoupled Co2FeAl/(Ga,Mn)As bilayer heterostructures at temperatures below the Curie temperature of (Ga,Mn)As, TC = 50 K, under photoexcitation of lowfluence, near-infrared pump pulses. The coherent magnetization precession persists to room temperature, indicating that proximity-induced ferromagnetism plays an important role in the optical excitation mechanism. A subsequent simulation of the temperature-dependent precession amplitude and frequency behavior is performed based on the Landau-Lifshitz-Gilbert (LLG) equation, suggesting that the high-efficiency excitation mechanism can be attributed to the modulation of the exchange coupling field at the interfacial area, which is induced by the emergence of the dynamic exchange coupling effect between the precessing magnetizations in the two ferromagnets. Second, the Gilbert damping property of the magnetization precession in the Co2FeAl/(Ga,Mn)As bilayer system is studied. At temperatures below the Curie temperature of (Ga,Mn)As, TC = 50 K, ultrafast pump excitation creates a counter-precessing, exchange-coupled mode in the ferromagnetic bilayer. The precessing magnetization in the Co2FeAl layer transfers a pure spin current directly into the (Ga,Mn)As layer at a certain intensity of external magnetic field where the Fe(Co) spins and the Mn spins precess at the same frequency. A photo-induced enhancement of the Gilbert damping constant α is observed, indicating that spin-angular momentum is transferred at the resonance magnetic fields. This can be attributed to the effect of the interfacial dynamic exchange coupling interaction between the precessing magnetizations in two ferromagnetic layers. A corresponding phase shift of the magnetization precession is also observed at the resonance field where the Gilbert damping peak appears.

One of the most promising systems for creating a working quantum computer is the triple quantum dots in a linear semiconductor. One of the biggest advantages is that we are able to perform Heisenberg exchange gates on the physical qubits. These exchanges are both fast and relatively low energy. Which means that they would be excellent for producing fast and accurate operations. In order to prevent leakage errors we use a 3 qubit DFS to encode a logical qubit. Here we determine the theoretical time dependent affects of applying the Heisenberg exchange gates in the DFS basis as well as the effect of applying multiple exchange gates at the same time. we also find that applying two heisenberg exchange gates at the same time is an effective way of implementing a leakage elimination operator.

Recent theoretical studies have suggested that the observed suppression of superconductivity in superconductor/ferromagnet (S/F) heterostructures could be modulated by controlling the ferromagnetic exchange interaction in the superconductor. The exchange interaction in the superconductor is the sum of the exchange interaction from the ferromagnetic regions, which has a phase and magnitude that depends upon the direction that the ferromagnet is magnetised and the distance. As the exchange interaction has a phase it is possible that the contribution from two regions will cancel out. The exchange interaction, which can be viewed as an imbalance in the spin populations, suppresses superconductivity so any reduction in the exchange interaction will increase the superconducting transition temperature (Tc) of the heterostructure. Thus by changing the magnetisation of the ferromagnetic regions it is possible to control the exchange interaction in the superconductor and so the superconducting properties of the heterostructure. I have measured the superconducting properties of niobium/cobalt bilayers as a function of the applied magnetic field. I have observed that one component of the superconducting properties is controlled by the net magnetisation rather than the magnitude of the applied field. I have been able to show that this component of the observed change in the superconducting properties is not simply due to stray magnetic field but that the superconductivity is being actively controlled by means of the exchange interaction. This is the first experimental evidence that the superconducting properties of a S/F heterostructure can be controlled in this way, which opens up the possibilities for the construction of future devices.

The Crystal River site (8CI1) is a Woodland-period mound (ca. 1000 BC to AD 1050) complex located on the west-central Gulf coast of Florida. Links to the Hopewell Interaction Sphere suggest that the people of Crystal River had connections with a broad range of communities, yet little is known concerning the role the site played in local, regional, or long-distance exchange networks. Pottery traditions vary amongst different communities of practice, therefore the level of interaction at Crystal River can be measured by looking at variation in the ceramic assemblage. I combine type/attribute, vessel form and function, gross paste, and chemical analyses to determine the amount of variability present in the pottery assemblage. These analyses show that Crystal River has a high level of ceramic variation with some spatial and temporal patterning. To determine Crystal River’s membership in and potential role within a sphere of interaction, I compare these patterns to three community types with diverse social interfaces. This research suggests that Crystal River may have started out as a homogenous, residential community but through time began to interact with a number of diverse, regionally associated communities drawn to the site for special occasions.

The main focus of this study is the influence of waves on the heat transfer over sea. In particular, the bulk transfer coefficient CH (the Stanton number), has been investigated for possible wave influence. Measurements from the site Östergarnsholm in the Baltic Sea have been used. The site has a large sector with undisturbed over water fetch. Data during the period 1995-1999 have been used. It is shown that CH behaves differently as it approach z/L=0 from the unstable side depending on the wave state. During growing sea, CH makes a rapid drop as it passes over neutrality, strikingly different from swell conditions where CH makes a much ’smoother’ transition. This difference is also shown to exist for the kinematic heat flux. Based on the definition of CH, it is suggested that one of the reasons of CH’s different behaviour for different stratification and wave state, is ought to be sought in the kinematic heat flux itself. A comparison of the w,θ cospectra during growing sea and swell conditions, showed differences. For growing sea, the larger size eddies dominates the heat flux during unstable conditions. There is no significant difference in peak frequency for different grade of instability. The swell cases showed a more inconsistent behaviour as it approached neutrality, with the peak frequency shifting for different stability ranges. The correlation coefficient between u, the longitudinal wind component, and w, the vertical wind component, Ru,w is also investigated in this study. It is shown that Ru,w is exposed to some wave influence. A comparison of Ru,w as a function of wave age, for neutral and non-neutral stratification is made. For swell cases and non-neutral stratification Ru,w makes a rapid drop and assumes values close to zero. This is not seen for the neutral cases although there is a slight decrease. It is concluded that a certain amount of positive heat flux and inactive turbulence is needed to see this drop in the correlation coefficient.
Sammanfattning av ”Våginflytandet på värmeutbytet över hav” Syftet med studien är att undersöka om det existerar ett våginflytande för värmeutbytet över hav och speciellt eventuellt våginflytande på utbyteskoefficienten CH (Stantons tal). Mätdata från Östergarnsholm utanför Gotland har använts. Denna mätstation har en stor sektor i vilken vindens anloppssträcka ostört är påverkad av hav. Data från perioden 1995–1999 har använts. Stantons tal CH beter sig annorlunda vid övergången från instabil till stabil skiktning beroende på havsytans tillstånd. Vid uppbyggande sjö gör CH ett ’hopp’ då det passerar neutral skiktning. För dyning finns inte detta hopp utan övergången är mycket mjukare. Denna skillnad observeras också hos det turbulenta värmeflödet. Baserat på definitionen av CH föreslås det att dess olika beteende för olika skiktning och vågtillstånd finns att söka i beteendet hos det turbulenta värmeflödet. En jämförelse av cospektrat för vertikal vind, w, och potentiell temperatur, θ, visar att där finns olikheter mellan uppbyggande sjö och dyning. Under instabila förhållanden och uppbyggande sjö domineras värmeflödet av storskaliga virvlar. Det existerar ingen signifikant skillnad i maximal värdets frekvens för olika grad av instabilitet. Dyningsfallen visar ett mer varierat beteende med en maximalvärdes frekvens som skiftar för olika stabilitetsområden. I studien undersöks också korrelationskoefficienten mellan longitudinal vind u, och vertikal vind w, Ru,w. Det visas att Ru,w är utsatt för ett visst våginflytande. Ru,w som en funktion av vågålder jämförs för neutral och icke-neutral skiktning. För dyning och icke-neutral skiktning så faller Ru,w snabbt till små värden nära noll. Detta resultat skiljer sig för neutral skiktning där Ru,w bara gör en svag minskning. Slutsatsen är att det krävs en viss mängd positivt värmeflöde och inaktiv turbulens för att se det kraftiga avtagandet hos korrelationskoefficienten.

The human society of today has a significantly negative impact on the environment and needs to change its way of living towards a more sustainable path if to continue to live on a healthy planet. One path is believed to be an increased usage of naturally degradable and renewable raw materials and, therefore, attention has been focused on the highly abundant biopolymer cellulose. However, a large drawback with cellulose-based materials is the significant change of their mechanical properties when in contact with water. Despite more than a century of research, the extensively investigated interaction between water and cellulose still possesses many unsettled questions, and if the answer to those were known, cellulose-based materials could be more efficiently utilized. It is well understood that one interaction between cellulose and water is through hydrogen bonds, established between water and the hydroxyl groups of the cellulose. Due to the very similar properties of the hydroxyl groups in water and the hydroxyl groups of the cellulose, the specific interaction-induced effect on the hydroxyl groups at a cellulose surface is difficult to investigate.  Therefore, a method based on 2H MAS NMR spectroscopy has been developed and validated in this work. Due to the verified ability of the methodology to provide site-selective information regarding the molecular dynamics of the cellulose deuteroxyl groups (i.e. deuterium-exchanged hydroxyl groups), it was shown by investigating 1H-2H exchanged cellulose samples that only two of the three accessible hydroxyl groups (on the surface of cellulose fibrils) exchange with water. This finding was also verified by FT-IR spectroscopy, and together with MD simulations we could establish that it is O(2)H and O(6)H hydroxyl groups (of the constituting glucose units) that exchange with water. From the MD simulations additional conclusion could be drawn regarding the molecular interactions required for hydrogen exchange; an exchanging hydroxyl group needs to donate its hydrogen in a hydrogen bond to water. Exchange kinetics of thin cellulose films were investigated by monitoring two different exchange processes with FT-IR spectroscopy. Specific information about the two exchanging hydroxyl/deuteroxyl groups was then extracted by deconvoluting the changing intensities of the recorded IR spectra. It was recognized that the exchange of the hydroxyl groups were well described by a two-region model, which was assessed to correspond to two fibrillary surfaces differentiated by their respective positions in the fibril aggregate. From the detailed deconvolution it was also possible to estimate the fraction of these two surfaces, which indicated that the average aggregate of cotton cellulose is built up by three to four fibrils.                       2H MAS NMR spectroscopy was used to examine different states of water in cellulose samples, hydrated at different relative humidities of heavy water. The results showed that there exist two states of water adsorbed onto the cellulose, differentiated by distinct different mobilities. These two states of water are well separated and had negligible exchange on the time scale of the experiments. It was suggested that they are located at the internal and external surfaces of the fibril aggregates. By letting cellulose nanofibrils undergo an epoxidation reaction with a mono epoxide some indicative results regarding how to protect the cellulose material from the negative impact of water were presented. The protecting effect of the epoxidation were examined by mechanically testing and NMR spectroscopy. It was proposed that by changing the dominant interaction between the fibril aggregates from hydrophilic hydrogen bonds to hydrophobic π-interactions the sensitivity to moisture was much reduced. The results also indicated that the relative reduction in moisture sensitivity was largest for the samples with highest moisture content.

QC 20161229

Dissertation (Ph.D. in Meteorology)--Naval Postgraduate School, June 2010.
Dissertation supervisor: Montgomery, Michael. "June 2010." Description based on title screen as viewed on July 14, 2010. Author(s) subject terms: Air-sea interaction, tropical cyclones, surface fluxes, drag coefficient, CBLAST. Includes bibliographical references (p. 125-131). Also available in print.

The information exchange between parents and personnel at preschools is held informally and mainly when the child is departed from the preschool. Interviews with parents and personnel at preschools were made to find out what this exchange consists of, what factors affect it, and if there are parts that may be improved by making them digital. Through these interviews, the information need was extracted and analyzed, and factors affecting the information exchange were identified. Parts of these findings where compiled into asoftware idea as an extension to the software for preschools provided by Tempus Information Systems ab, where this master’s thesis was conducted.Requirements for the software were gathered and prioritized. Prototypes were made,tested, and evaluated leading to the development of a web application. The application supports input of chosen parts of the information need in order to make it accessible forparents. It is intended to be used by the personnel and to run on a tablet mounted on thewall, helping their everyday tasks, as well as being a service to parents of smaller children. This information could then be retrieved by the parents when the child is departed from theTempus Touch software at the preschool, thus freeing the information exchange to qualitative matters about the child’s well-being. It could also be accessible through the Tempus web or mobile application while at home.

The immune response of chickens immunized with β-N-acetylglucosaminidase was monitored in the egg yolks of the birds using an enzyme-linked immunosorbent assay. Significantly higher levels of specific antibodies were detected in the yolks of the birds immunized with the enzyme when compared with the yolks of a control bird collected over the same period significant differences also were found in the response within the immunized group of birds, indicating individual variability to the injections. Immunoglobulins were isolated from egg yolk after a preliminary purification using alginate to precipitate lipoproteins. A ten millilitre DEAE-Sephacel ion exchange chromatography column resulted in a final product containing 16 mg of IgG with a purity of 60% when 50 mL of an egg yolk supernatant was applied. Specific antibody activity toward the antigens β-lactoglobulin and E. coli lipopolysaccharide was higher in both cases in the isolated immunoglobulin fractions which contained lower purity (40%). Lower antibody activity was observed in the 60% purified fractions. Separation of specific antibodies from non-specific antibodies appeared to occur, possibly due to the given characteristics of the specific antibodies, or due to the differences exhibited by chicken IgG subpopulations. Using metal chelate interaction chromatography, a 10 mL copper-loaded column was able to yield 104 mg of IgG with a purity of 75% when 200 mL egg yolk supernatant was applied. Again, the heterogeneous nature of chicken IgG was illustrated. A comparison of the two chromatographic techniques indicated the advantages of metal chelate interaction chromatography over ion exchange chromatography under the conditions examined. Applications of the chicken IgG isolated by metal chelate interaction chromatography to an enzyme-linked immunosorbent assay for the detection of β-N-acetylglucosaminidase was attempted. Linear relationships were obtained when standard solutions of the enzyme were used in the assay. The results indicate that MCIC-isolated chicken immunoglobulins have excellent potential for use in analytical tests.
Land and Food Systems, Faculty of
Graduate

The notion that trade and capital flows drive exchange rates is widespread in the financial press but receives scant attention in economic research. The flow market model of the exchange rate has fallen out of fashion in the 1970s, at a time when stock-oriented approaches, such as monetary and portfolio balance models, gained prominence. However, given the limited empirical success of mainstream exchange rate models over the past decades, it may be time for a reassessment of the flow market approach. The aim of this work is to demonstrate how balance of payments imbalances influence the demands for different currencies in the foreign exchange markets over time. A dynamical system approach is used to assess how international payments evolve for different sets of assumptions regarding the joint dynamic behaviour of various balance of payments components. An important finding is that while the different components of the balance of payments affect international payment flows directly in a given country, they also determine the accumulation of foreign assets and liabilities in that country, or its international investment position. However, the international investment position itself gives rise to international payments, for instance when foreign debt becomes due and is repaid or when interest payments on the existing debt stock are made. The dynamical system approach is further applied to topics such as currency crises and the exchange rate performance of commodity exporters. Two empirical essays on the important case of Japan confirm the above hypotheses. The first essay builds a vector error correction model for the nominal exchange rate and the current account in Japan. The model allows for a Markov-switching stochastic trend in the current account. The model is capable of producing the strong cycles of the current account and the gradual adjustment of the exchange rate, which can both be observed in the Japanese data. Bayesian estimation proceeds using an innovative Gibbs sampling procedure. The second essay estimates the maturity structure of Japan's foreign lending. It constructs an explicit measure of cross-border payment flows across Japanese borders, based on the estimated maturity structure of Japan's foreign lending. The simulated cross-border payment flows are shown to closely follow the movements of the Japanese exchange rate. An additional empirical essay considers the reverse question of how the current account is influenced by exchange rate fluctuations. Based on German and Japanese data, it is shown that strong exchange rate movements have tended to influence the trend of the current account, rather than its level as is typically assumed in the literature.

For users away from the office or home, there is an increasing demand for mobile solutions that offer effective collaborative facilities on the move. The mobile cellular device, or “smart phone”, can offer a ubiquitous platform to deliver such services, provided that its many physical and technological constraints can be overcome. In an effort to better support mobile collaboration, this thesis presents a contributing Mobile Exchange Architecture (MEA) designed to improve upon the capabilities provided by mobile devices to enable synchronous exchange of digital media during a phone conversation using wireless networks and cellular devices. This research includes the design and development of one such MEA in the form of a fully functional Photo-conferencing service, supporting shared remote interaction techniques, simultaneous voice communication and seamless digital media exchange between remote and collocated mobile users. Furthermore, through systematic design, experimental evaluations and field studies we evaluate the effects of different shared remote interaction techniques – 'pointing', 'scaling', 'mixed' and 'hybrid' – assessing the task effort required by users when interacting around shared images across resource constrained mobile devices. This thesis presents a direction for the future development of technologies and methods to enable a new era of scalable always-to-hand mobile collaborative environments.

L’objectif principal de cette recherche était d’examiner l’interaction entre élèves d’ALS et de FLS de sixième année du primaire du Québec et de l’Ontario communicant par clavardage et utilisant l’approche en Tandem. Plus spécifiquement, elle visait à vérifier si ces apprenants offraient de la rétroaction corrective et, le cas échéant, si cette dernière suscitait de la réparation. L’opinion des participants par rapport à leur expérience de communication en Tandem a été examinée. Les sessions de clavardage ont eu lieu sur une période de quatre mois produisant 16 séances de clavardage (8 en anglais et 8 en français). Les résultats montrent que des apprenants de langue seconde ont offert de la rétroaction corrective à 370 occasions. L’examen des données révèle que les sujets ont utilisé les trois types de rétroaction: la rétroaction explicite, la reformulation et la négociation de la forme. Contrairement à ce qui a pu être observé dans d’autres études antérieures impliquant de jeunes apprenants, une des découvertes majeures de cette recherche fut l’utilisation, par les participants, de la rétroaction explicite plutôt que la reformulation. Par contraste avec la recherche de Morris (2005) qui impliquait également de jeunes apprenants de niveau primaire utilisant le clavardage, le taux de réparation a été plutôt bas. La grande majorité des élèves d’ALS ont aimé utiliser l’ordinateur comme moyen d’apprentissage de leur L2 et de leur L1 contrairement aux élèves de FLS. Les implications pédagogiques des résultats de cette recherche ainsi que des suggestions pour de futures recherches sont également discutées.
The main objective of this research was to examine the interaction between ESL and FSL sixth graders in Quebec and Ontario communicating in a Tandem chat project. More specifically, it aimed to find out if participants provided each other with different types of corrective feedback and whether this feedback led to repair. It also examined how the students viewed this project. The chat sessions took place over four months and involved the completion of 16 tasks (8 in English and 8 in French). The results showed that L2 Grade 6 students provided feedback to their chat partners in 370 instances. The students in both the ESL and FSL exchanges provided three types of feedback: explicit, recasts, and negotiation of form. A major finding is that unlike previous studies involving young learners, the preference was for explicit feedback rather than recasts. In contrast to the Morris’ (2005) study which also involved young learners engaged in chat, the rate of repair was very low. Unlike the FSL students, the great majority of ESL students liked the chat exchange and found it useful not only for learning their L2 but also their L1. The pedagogical implications of this study as well as suggestions for future research are discussed.

There is a well-known expression that reads: “Communication is key”. That applies to our everyday life, work, relationships and more. Communication helps to make sure everyone is informed, and by doing so, avoiding misunderstandings. Effective and valuable internal communication is also a success factor and an essential part of an organizations’ structure. This study aimed to help staff at the Intensive Care Unit (ICU) at Örnsköldsvik hospital. This paper presents results from a study performed, with the objective to investigate how a digital dashboard should be designed to make management and responsible specialist feel confident that they reach out to all team members and also receives communicated information in a hospital environment. This was done by conducting a user-centered design process to analyze, design and implement a digital dashboard that later on was used in a final study including a test period and evaluation. For a period of 2 weeks, the implemented digital dashboard was tested at the ICU in a hospital. After that period, the dashboard was evaluated by the staff members using a questionnaire, and an interview with the responsible administrator of content. The result suggest that the management and responsible specialist felt that the digital dashboard makes them reach out to all other team members better, compared to their current communication channels. In addition, the vast majority of team members felt that they receive communicated information better. By using a digital dashboard as an internal communication platform, information exchange within the staff at the ICU was improved.

Purpose: The aim of the research is to investigate what successful booksellers provide in store that increase interaction and thereby enhance perceived value for the customers. Approach: The study is based on a combination of using both quantitative and qualitative data, collected through questionnaire and through face-to-face interviews. A deductive approach has constituted the paper as the theoretical framework was constructed upon already existing theories. Findings: The investigated booksellers are working with all of the three interaction facilitators; servicescape, shopping event as well as employee competence to create interaction in store that thereafter through relating, communicating and knowing increase the customer perceived value. The success behind the booksellers is based on their niche and personal approach that is thoroughly implemented in their offerings, which will create a community feeling. The personal relationship with the customers gives a structural support for the communication that in the end increase the knowledge. However, the knowledge renewal was more vital for the employees in order to provide personal service. Practical implications: Brick-and-mortar stores should fully acknowledge the importance of interacting with customers, by implementing servicescape, shopping event and employee competence with a personal touch. It is important to be as physical as possible and use the store as a social meeting place. The store should create a unique atmosphere, where like-minded customers socialize. The employee competence is vital for the brick-and-mortar stores in order to provide personal service. Theoretical implications: Grönroos and Voima’s (2012) Value creation sphere-model was extended by integrating Ballantyne and Varey’s (2006) triangulated value-enable-model into the joint sphere of Grönroos and Voima’s (2012) model. Since both of the models were tested empirically the paper supplies empirical evidence for both of the theoretical models.

Aquesta tesi explora l'aparició de la identitat en la interacció multimodal dins d'un context situat en un intercanvi virtual, és a dir "un programa d'educació persona-a-persona, sostingut i habilitat per la tecnologia". Considera que la identitat és construïda a través del discurs i reconstruïda cada cop que abordem una interacció, i que els contextos situats en una interacció poden limitar igual a augmentar les oportunitats dels individus per abordar l'ús del llenguatge i la construcció de la identitat. Entendre com els alumnes construeixen i representen identitats en determinats contextos pot ajudar-nos en el disseny educatiu i la implementació de processos de l'aprenentatge de la llengua. La tesi comença presentant un marc per a l'anàlisi de la identitat en contextos "en línia", basat en propostes etnogràfiques i centrades en el discurs sobre la identitat en la interacció, la investigació en la Comunicació Mediada per l’Ordenador (CMO) i la multimodalitat. Aquest marc em permet explorar la identitat en l'intercanvi virtual en diversos nivells. Primer de tot miro els fonaments ideològics, polítics i teòrics d’un programa virtual que va ser dissenyat per gestionar la relació entre les "societats occidentals" i les "societats predominantment musulmanes". Posteriorment exploro el paper del mediador i la potencialitat de l'ús de tecnologies asíncrones i síncrones multimodals adoptades per a la interacció i la construcció de la identitat en el programa virtual. Finalment analitzo els patrons d'interacció i el posicionament de la identitat d'un grup particular de gent jove connectat des de Palestina, Tunísia, Egipte, Jordània, Qatar i els Estats Units per participar en el "diàleg facilitat" a l’intercanvi al llarg d'un període de 7 setmanes. Els meus resultats indiquen que les identitats en aquest context són fluides i emergents, igual a les dinàmiques del poder dins de les interaccions. Les relacions de poder entre els facilitadors i els participants són asimètriques i això es reflecteix en certs intercanvis, però els facilitadors també gestionen les dinàmiques de poder creant un espai segur i, a través de ‘fer transcripcions’ de les interaccions en el xat de text, ajuden la comprensió entre els participants. En conseqüència, les dinàmiques de poder canvien, des de principi en les primeres sessions, quan els participants van iniciar les interaccions, i més endavant, quan van qüestionar, van desafiar i van construir el coneixement basades en les perspectives d'uns i d’altres. A intentar comprendre el 'altre', els participants fan rellevant el seu propi identitat i el de les identitats locals viscudes, per exemple ser un jove a Tunísia o Egipte en un moment històric quan la gent havia pres els carrers per demanar un canvi; o el fet de ser un jove americà que està en desacord amb, o sap poc sobre la política exterior del seu govern. El participants utilitzen aquestes identitats, dins del context d'un grup de diàleg, amb el mateix objectiu de compartir i adquirir una major comprensió de l'altre. El context de diàleg ajuda a molts dels participants trobar la seva pròpia veu, tot i que hi ha asimetries en termes de competències de la llengua, en les dinàmiques de poder i hi ha diferència de coneixements de la geopolítica. La investigació en aquesta àrea és rellevant, particularment avui en dia que està marcat per la crisi dels refugiats, l'augment de les nacionalismes i les populismes, les alertes terroristes i la por de ‘l'altre'. Els polítics demanen als educadors que ajuden els estudiants a tenir una actitud positiva vers a la diferència, i que desenvolupin coneixements pràctics digitals i la consciència crítica. Evidentment hi ha una necessitat urgent per a una millor comprensió de com es pot fer això. Busco ressaltar com es poden aplicar algunes dels resultats d'aquest estudi en el disseny de contextos en línia i multimodals que ofereixin als alumnes la possibilitat de posicionar-se lliurement les seves diferents identitats.
Esta tesis explora la aparición de la identidad en la interacción multimodal dentro de un contexto situado en un intercambio virtual, es decir “un programa de educación persona-a-persona, sostenido y habilitado por la tecnología”. Considera que la identidad es construida a través del discurso y reconstruida cada vez que abordamos una interacción, y que los contextos situados en una interacción pueden tanto limitar como aumentar las oportunidades de los individuos para abordar el uso del lenguaje y la construcción de la identidad. Entender como los alumnos construyen y representan identidades en determinados contextos puede ayudarnos en educación al diseñar y implementar los procesos del aprendizaje de la lengua. La tesis empieza presentando un marco para el análisis de la identidad en contextos “online”, basado en propuestas etnográficas y centradas en el discurso sobre la identidad en la interacción, la investigación en la Comunicación Mediada por el Ordenador (CMO) y la multimodalidad. Este marco me permite explorar la identidad en el intercambio virtual en varios niveles. Primero de todo miro los fundamentos ideológicos, políticos y teóricos del intercambio virtual, un programa virtual que fue diseñado para gestionar la relación entre las “sociedades occidentales” y las “sociedades predominantemente musulmanas”. Posteriormente exploro el papel de mediador y la potencialidad del uso de tecnologías asíncronas y síncronas multimodales adoptadas para la interacción y la construcción de la identidad en el intercambio virtual. Finalmente analizo los patrones de interacción y el posicionamiento de la identidad de un grupo particular de gente joven conectado desde Palestina, Túnez, Egipto, Jordania, Qatar y los Estados Unidos para participar en el “diálogo facilitado” en el intercambio a lo largo de un periodo de 7 semanas. Mis hallazgos indican que las identidades en este contexto son fluidas y emergentes, como lo son las dinámicas de poder dentro de las interacciones. Las relaciones de poder entre los facilitadores y los participantes son asimétricas y esto se refleja en ciertos intercambios , pero los facilitadores también gestionan las dinámicas de poder creando un espacio seguro y asumiendo el control de las interacciones apoyando la comprensión a través de transcripciones. En consecuencia las dinámicas de poder cambiaron desde las primeras sesiones, cuando los participantes no iniciaron muchas interacciones en comparación con sesiones posteriores, cuando empezaron cuestionar, desafiar y construir conocimientos basados en las perspectivas de unos y otros. Al intentar comprender el ‘otro’, los participantes hacen relevante suyo propio identidad y el de las identidades locales vividas, por ejemplo ser un joven en Túnez o Egipto en un momento histórico cuando la gente había tomado las calles para demandar un cambio; o el hecho de ser un joven americano que está en desacuerdo con o sabe poco sobre la politicaasimetríasexterior de su gobierno. Utiliza estas identidades, dentro del contexto de un grupo de diálogo, y tienen el mismo objetivo de compartir y adquirir una mayor comprensión del otro. El contexto les permitió a muchos de los participantes encontrar su propia voz, a pesar de las asimetrías en términos de competencias del lenguaje, en las dinámicas de poder y las diferencias de conocimientos de la geopolítica.
This thesis explores the emergence of identity in multimodal interaction within the situated context of a virtual exchange, that is a "technology-enabled, sustained, people-to-people education program". It takes the view that identity is discursively constructed and reconstituted every time we engage in interaction, and that the situated contexts of interaction can both limit and enhance opportunities for individuals to engage in language use and identity construction. Understanding how learners construct and enact identities in certain contexts can thus help us in the design and implementation of online language learning in education. This thesis begins by presenting a framework for the analysis of identity in online contexts, based on ethnographic and discourse-centred approaches to identity in interaction, research on CMC and multimodality. This framework allows me to explore identity in virtual exchange on various levels. I first of all of look at the ideological, political and theoretical underpinnings of a virtual exchange which was designed to address the relationship between ‘Western societies’ and ‘predominantly Muslim societies’. I then explore the mediating role and the affordances of the multimodal, asynchnronous and synchronous technologies adopted for interaction and identity construction in the exchange. Finally, I analyse the patterns of interaction and identity positionings of one particular group of young people connecting from Palestine, Tunisia, Egypt, Jordan, Qatar and the United States to engage in “facilitated dialogue” in the virtual exchange over a period of 7 weeks. Findings indicate that identities in this context are fluid and emergent, as are the power dynamics within interactions. The power relations between facilitators and participants are asymmetric and this is reflected in certain exchanges, but the facilitators also address power dynamics by supporting understanding through transcription, and supporting the participants in creating a safe space and to take control of the interactions. Power dynamics thus shifted as participants initiated interactions, questioned, challenged and built upon one another’s perspectives. In seeking to gain understanding of the “other”, interactants made relevant their own and each others’ local and lived identities, for example being a young person in Tunisia or Egypt at a historic time when people have been taking to the streets to demand change or being a young American who disagrees with or knows little about his government’s foreign policy. Orienting to these identities in the context of a facilitated dialogue group with the shared goal of acquiring greater understanding of the “other” allowed many of the participants to find a voice, despite the asymmetries in terms of language competence, quality of connection and knowledge of geopolitics. Research in this area is relevant, particularly in the current time which is marked by refugee crises, increased nationalisms and populisms, terror alerts and fear of the “other”. Policy makers are calling on educators to have students engage positively with difference, develop digital literacies and critical awareness and there is an urgent need for greater understanding as to how this can be done. I seek to highlight how we can apply some of the findings of this study to the design of learning in multimodal online contexts which offer learners a range of identity positionings.

Using both quantitative and qualitative methods of inquiry, this dissertation study undertakes an exploration of the dynamics of the social interaction in discourse co-constructed by pairs of college students in telecollaborative tandem exchanges. Two groups of participants, Mexican learners of English as a foreign language and American learners of Spanish as a foreign language, participated in video-based telecollaborative tandem exchanges where they worked in pairs to discuss topics assigned by their instructors, communicating half the time in Spanish and half in English. According to the principle of reciprocity in tandem learning, the participants switch between the roles of native speaker (NS) expert and non-native speaker (NNS) learner as they invest equal time, effort, and interest in each language part of the chats. Grounded in sociocultural theory (SCT) for second language acquisition (SLA), this study addresses research questions pertaining to (1) the distribution of talk between the members of each pair and between the language parts of the exchange, (2) the distribution of interactional resources deployed by the members of each pair to establish and maintain intersubjectivity and build a relationship, and (3) the individual experiences of participants regarding their positioning in and perspectives of the exchange. Addressing the three research questions allowed the researcher to look at the telecollaborative tandem exchanges from the perspectives of language production, social aspects of interaction, and individual experiences and perspectives to gather a deeper understanding of the tandem context. The analysis of three data sources—survey responses, chat transcripts from one chat of the semester-long telecollaborative tandem project, and post-project participant interviews—shows that the principle of reciprocity posited by tandem theorists as equal time, effort, and interest in each language part underestimates the complexity of the construct as it was created by the participants in the telecollaborative tandem interactions examined in this dissertation study. A mixed methods approach allowed the researcher to deconstruct and reconsider the construct of reciprocity in telecollaborative tandem learning. The telecollaborative tandem exchanges examined in this study were not reciprocal between language parts of the exchange in terms of language production, use of interactional resources, or tandem participant positioning. Instead, they presented complex pair relationships that used language differently in each language part to establish and maintain intersubjectivity, as well as the strong desire of the participants to position themselves and their partners as peers rather than take on the roles assumed to characterize the tandem context; that is, NS as expert and NNS as learner. In accordance with these findings, telecollaborative tandem learning should be approached with an open understanding of the concept of reciprocity in which the participants co-construct their relationship through meaningful social dialogue as peers, rather than through the roles of NS expert and NNS learner. Based on the findings of this study, the expert–learner model of reciprocity may be too rigid and too static for the dynamic context of telecollaborative tandem learning.

Mobile social software tools have great potential in transforming the way users communicate on the move, by augmenting their everyday environment with pertinent information from their online social networks. A fundamental aspect to the success of these tools is in developing an understanding of their emergent real-world use and also the aspirations of users; this thesis focuses on investigating one facet of this: the exchange of social media. To facilitate this investigation, three mobile social tools have been developed for use on locationaware smartphone handsets. The first is an exploratory social game, 'Gophers' that utilises task oriented gameplay, social agents and GSM cell positioning to create an engaging ecosystem in which users create and exchange geotagged social media. Supplementing this is a pair of social awareness and tagging services that integrate with a user's existing online social network; the 'ItchyFeet' service uses GPS positioning to allow the user and their social network peers to collaboratively build a landscape of socially important geotagged locations, which are used as indicators of a user's context on their Facebook profile; likewise 'MobiClouds' revisits this concept by exploring the novel concept of Bluetooth 'people tagging' to facilitate the creation of tags that are more indicative of users' social surroundings. The thesis reports on findings from formal trials of these technologies, using groups of volunteer social network users based around the city of Lincoln, UK, where the incorporation of daily diaries, interviews and automated logging precisely monitored application use. Through analysis of trial data, a guide for designers of future mobile social tools has been devised and the factors that typically influence users when creating tags are identified. The thesis makes a number of further contributions to the area. Firstly, it identifies the natural desire of users to update their status whilst mobile; a practice recently popularised by commercial 'check in' services. It also explores the overarching narratives that developed over time, which formed an integral part of the tagging process and augmented social media with a higher level meaning. Finally, it reveals how social media is affected by the tag positioning method selected and also by personal circumstances, such as the proximity of social peers.

The intense increase in energy consumption around the world has prompted a great deal of research on alternative and sustainable energy storage systems such as organic batteries. The fundamental understanding of the physics of organic salts and the ion insertion mechanism plays a key role in the development of electrode materials used in such sustainable batteries. The system studied in this project is of Lithium (2,5-dilithium-oxy)-terephthalate where a previous project studied this system from a different angle.  The electronic structure generation of the system is based on Density Functional Theory (DFT) along with an evolutionary algorithm to find the structures with minimum energy. The effects of varying the description of the exchange-correlation interaction were studied while introducing lithium ions to the system. This was done while also monitoring the repercussions of crystal structure optimization on the voltages, charge redistribution, and bonds of the system. The geometrical optimization of the hybrid functional resulted in the potential of the 2-electron step between Li2-p-DHT/ Li4-p-DHT of 2.6 V being closer to the experimental value recorded at 2.7 V.

Regions of surface water and groundwater exchange are major sites for the transfer and transformation of solutes and nutrients between stream and subsurface environments. Conventional stream and groundwater exchange investigations are limited by methodologies that require intensive field investigations and/or the set-up of expensive infrastructure. These difficulties are exacerbated where hydraulic gradients are very low and stream discharge highly variable. This thesis uses a suite of environmental tracers (Cl-, Rn-222, H-2 & O-18, Sr-87/Sr-86) to characterise the extent of stream and groundwater exchange between a sand bed stream and adjacent alluvial aquifer in a subtropical catchment (the Wollombi Brook) of eastern Australia. The aims were to identify sources and relative contributions of different sources of groundwater to stream discharge and specifically to improve the methodology of using Rn-222 to obtain quantitative estimate of groundwater fluxes. The sensitivity of the Rn-222 technique for identifying groundwater discharge based on the Rn-222 concentration in stream water was improved via an iterative numerical approach to account for Rn-222 loss from stream water via turbulent gas exchange and radioactive decay. Optimal distances between stream sampling points for defining the magnitude of groundwater discharge to stream flow based on Rn-222 concentrations in stream water is a function of average stream velocity and water depth. The maximum allowable distance between sampling points for determining the magnitude of groundwater discharge to the Wollombi Brook was 2 km. This work showed that groundwater discharged to all reaches of the Wollombi Brook during baseflow and flood recession conditions. Alluvial groundwater contributed less than 30% of water to stream flow in the mid Wollombi Brook catchment. Dilution of steady-state Rn-222 concentrations measured in transects from the stream to the alluvial sediments showed that significant surface water and groundwater exchange occurs even when gradients between surface water and groundwater are low. Lateral stream water influx to the adjacent alluvial aquifer was more extensive in the lowland areas of the Wollombi Catchment during low flow than flood recession conditions. Extensive stream water influx to the adjacent alluvial aquifer occurs contrary to the net direction of surface water and groundwater flux (as indicated by hydraulic gradients toward the stream channel). The rate of stream and groundwater exchange within the adjacent alluvial aquifer appears to be greatest during baseflow conditions. Fresh alluvial groundwater appeared to provide a buffer against higher salinity regional groundwater discharge to the alluvial aquifer in some reaches of the Wollombi Brook catchment. Pumping of the alluvial aquifer and diversions of surface water may jeopardise the water quality and volume of the alluvial aquifer and induce water flow from the regional aquifer toward the stream, potentially salinising the fresh alluvial aquifer and subsequently the stream. The change in the Cl- concentration and the variation in slope of the deuterium � oxygen-18 line between consecutive stream sampling points could be used to differentiate between regional and alluvial groundwater discharge to stream flow. Incorporating this information with three-component end-member mixing using [Sr2+] and Sr-87/Sr-86 showed that stream and alluvial groundwater exchange within the stream channel was highest in the lowland floodplains during low flow conditions. The least stream and alluvial groundwater exchange occurred in the low streambed gradient mid reaches of the Wollombi Brook regardless of stream stage. The greatest difference in the degree of stream and alluvial groundwater exchange between high and low stream stages occurred in the lowland floodplains of the Wollombi Brook.

This thesis analyses the relationship between the increasingly important sovereign CDS spreads and exchange rates, from a macroeconomic perspective. It attempts to address an existing gap in the empirical literature, which to date has paid limited attention to the role of exchange rates in influencing sovereign CDS spreads, and vice versa. In exploring the relationship between sovereign CDS markets and foreign exchange markets, I find relatively strong evidence of a causal relationship between these two variables. In a longer-term cointegrating relationship, I find that sovereign CDS spreads have different impacts (positive or negative) on exchange rates depending on the structural characteristics of the domestic export sectors of the countries studied. Turning to the second moment of exchange rates and sovereign CDS spreads, I examine the relationship between the volatility of sovereign CDS spreads and the volatility of exchange rates for developed economies (proxied by an index containing 10 Eurozone countries) and emerging economies (proxied by Brazil and Russia). My findings point to different mechanisms of transmission between sovereign CDS markets and foreign exchange markets with regard to developed and emerging economies: for developed economies, exchange rates affect sovereign CDS spreads through the volatility, whilst in emerging economies the exchange rates affect sovereign CDS spreads at the price level. To further analyse the determinants of sovereign CDS spreads, I incorporate additional macroeconomic fundamentals in addition to exchange rates into a model to explain sovereign CDS spreads. The results show that sovereign CDS spreads are indeed driven by most macroeconomic fundamentals. However, these results do not hold during periods of economic turmoil, in which the rising risk aversion of investors becomes a principal influence behind the sovereign CDS spreads. As changes in exchange rates are able to capture changes to risk aversion through trading in foreign exchange markets, the exchange rate retains its explanatory power to sovereign CDS spreads in ‘normal’ as well as ‘crisis’ conditions. Overall, the study provides strong support for the claim that exchange rates are an important determinant of sovereign CDS spreads, in addition to the interest rate which is highlighted in the literature review. The exchange rate – as an important fundamental indicator – can reflect the general domestic economic status, the relative international competitiveness of countries, as well as capture changes in risk aversion among investors. Therefore, using exchange rates to explain sovereign CDS spreads can help to account for both domestic and international dimensions of the ‘health’ of an economy as well as changes in investors’ attitudes.

My research focuses on issues relating to the dynamics of cross cultural contact and exchange in the Western Mediterranean (in particular, Southern France and North Eastern Spain) between the late seventh and the late sixth century BC, a period of great innovation and changes in both regions. My work focuses on the ways in which some of the objects acquired through encounter with traders from different cultural backgrounds were integrated in the material culture of these regions, how they were perceived in the geographical and social contexts in which they were acquired and how they could be used to establish or maintain identities and statuses.

This dissertation focuses on the preparation of polymeric monolithic capillaries for ion exchange chromatography of peptides and proteins, since polymeric monoliths have shown promise for providing improved protein separations. Characteristics of monolithic columns include low back pressure, simplicity of fabrication and biocompatibility. Preparation of strong and weak cation-exchange monolithic stationary phases in 75 μm I.D. capillaries by direct in situ copolymerization was achieved using various functional monomers including sulfopropyl methacrylate, phosphoric acid 2-hydroxyethyl methacrylate, bis[2-(methacryloyloxy)ethyl] phosphate and 2-carboxyethyl acrylate with polyethylene glycol diacrylate and other PEG materials. The resulting monoliths provided excellent ion exchange capillary LC of peptides and proteins with good run-to-run [relative standard deviation (RSD) < 1.99%] and column-to-column (RSD < 5.64%) reproducibilities. Narrow peaks were obtained and peak capacities of over 20 were achieved. Dynamic binding capacities of over 30 mg/mL of column volume for lysozyme were measured. A single monomer was used to synthesize a phosphoric acid containing monolith to improve its stability and reproducibility. The monolith was synthesized from only BMEP in 75 μm I.D. UV transparent fused-silica capillaries by photo-initiated polymerization. A dynamic binding capacity (lysozyme) of approximately 70 mg/mL of column volume was measured. Efficiencies of 52,900 plates/m for peptides and 71,000 plates/m for proteins were obtained under isocratic conditions. Good reproducibilities were achieved. Zwitterionic monolithic columns based on photo-initiated copolymerization of N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl)ammonium betain and poly(ethylene glycol) diacrylate were prepared in 75 μm I.D. fused silica capillaries for hydrophilic interaction chromatography. Inverse size exclusion chromatography was used to characterize the pore structure of the resulting monolith. A typical hydrophilic interaction chromatography mechanism was observed when the organic content in the mobile phase was higher than 60%. Good separations of amides, phenols, and benzoic acids were achieved. The effects of mobile phase pH, salt concentration, and organic modifier content on retention were investigated.

The dynamic nature of eukaryotic chromatin enables the packaging of large amounts of genetic material in a small space. At the same time, it provides controlled access to genomic DNA for a variety of nuclear processes for example, transcription and DNA repair. The transition between open and closed chromatin states is largely governed by ATP-dependent chromatin remodeling complexes, which operate on nucleosomes in concert, to modulate chromatin structure and composition. Exchange of the canonical and variant forms of histones in nucleosomes, and altering the spacing between consecutive nucleosomes, are two major ways which regulate chromatin-based processes and chromatin higher-order organization. The evolutionarily conserved INO80 and ISW1a complexes mediate these two aspects of nucleosome remodeling, respectively. Despite sharing conserved domain architecture of the core remodeling machinery, chromatin remodelers differ significantly in their modes of interaction with nucleosomes, and how they alter histone-DNA contacts. In this study, we have used a site-specific photocrosslinking approach coupled with peptide mapping to determine the interactions of subunits and domains of the S. cerevisiae INO80 and ISW1a complexes with nucleosomes. We find that specific interactions of remodelers with different regions of the nucleosome largely dictate their specialized functions and mechanisms. The ATP-dependent helicase-like (ATPase) domains of remodelers belonging to the ISWI and SWI/SNF families translocate along DNA close to the center of nucleosomes in order to mobilize, space or disassemble nucleosomes. In contrast, we observed that INO80 has a strikingly distinct mechanism, which is different even from its paralog SWR1. INO80 mobilizes nucleosomes as well as catalyzes the exchange of histone variant H2A.Z for the canonical histone H2A, while SWR1 mediates the reverse exchange of H2A for H2A.Z, without being able to mobilize nucleosomes. We have found that INO80, in order to promote H2A-H2B dimer exchange, translocates along DNA at the H2A-H2B interface close to the edge of nucleosomes and persistently displace DNA from H2A-H2B. Blocking either DNA translocation or the accumulation of DNA torsions close to the edge of the nucleosome interferes with this dimer exchange by INO80. SWR1 and other SWI/SNF and ISWI remodeling complexes translocate along DNA at the H3-H4 interface and do not persistently displace DNA from the histone octamer as does INO80. This study shows for the first time an ATP-dependent chromatin remodeler that invades nucleosomes at the DNA entry site instead of the center − a more logical approach for the displacement of H2A-H2B. We also investigated nucleosomal DNA interactions of other INO80 subunits and domains to understand the architecture of INO80 bound to nucleosomes. We found that the HSA (helicase-SANT-associated) domain of Ino80 along with actin-related protein (Arp) subunits Arp8 and Arp4 bind to the extranucleosomal DNA and is potentially involved in a coupling mechanism with the ATPase domain to regulate its activity. We also mapped the DNA binding regions of Arp8 and Arp4, which might be involved in recruiting INO80 to genomic sites. The ISWI remodeler ISW1a regulates the distance (spacing) between nucleosomes in an array by simultaneously interacting with two nucleosomes and directionally remodels one of them. We mapped DNA interactions of ISW1a subunits in mono- and di-nucleosomes. Our results show that the catalytic Isw1 subunit specifically interacts with the region of DNA translocation and DNA entry site of the asymmetrically positioned nucleosome in a di-nucleosome, which is preferentially mobilized. In contrast, the Ioc3 subunit interacts extensively with the linker DNA as well as the extranucleosomal DNA of the un-remodeled nucleosome. This bias in nucleosomal DNA interactions of ISW1a enables directional remodeling, which reveals the molecular basis of nucleosome spacing. We have identified a novel domain within the non-catalytic Ioc3 subunit of ISW1a that regulates nucleosome spacing. We found that when this domain is deleted, the catalytic Isw1 subunit loses its specificity and interacts with both the nucleosomes of a di-nucleosome substrate. This is consistent with the domain-deleted ISW1a mobilizing both nucleosomes efficiently, leading to the loss of its nucleosome spacing activity. In summary, this dissertation explores how different remodeling complexes have customized and regulated modes of nucleosome interaction in order to accomplish specialized remodeling outcomes. INO80 places its ATPase domain for translocation at the H2A-H2B dimer interface and persistently displaces DNA from its surface to promote H2A.Z exchange. Nucleosome spacing by ISW1a requires the catalytic Isw1 subunit to engage with and reposition one out of two consecutive nucleosomes in an array, while the Ioc3 subunit likely monitors the distance between them.

The Golgi apparatus is the main crossroad of the intracellular trafficking network in all eukaryotic cells and plays a crucial role in the distribution of cellular material. To ensure the proper sorting and delivery of cargo proteins to their destination while maintaining Golgi homeostasis the coordination of all transport events to and from this organelle is required. Although a cascade of activation events has already been reported for Golgi Ypt/Rab proteins that function in the exocytic pathway, their connection to incoming vesicles from endosomal compartments or to the different Arf mediated vesicle formation machineries has still to be established. In addition, the role of lipids and the interplay between lipid and protein regulators at the Golgi are largely missing. In the present study, we used several approaches to unravel the crosstalk between known regulators of Golgi trafficking and to identify new proteins involved in this process. As starting point, we considered the results from four different screens before focusing on the role of Arf exchange factors. We report two new physical interactors of the late Golgi Arf-GEF Sec7p: the lipid kinase Pik1p and the cyclic nucleotide phosphodiesterase Cpd1p. In addition, our studies on the function of Sec7p revealed additional feature of this protein and it’s relationship to the other yeast Golgi Arf-GEFs. Arf proteins and their regulators play an important role in the formation of vesicles at the exit from the Golgi apparatus. There are three Golgi-localized Arf-GEFs in S.cerevisiae, Sec7p and the redundant Gea1p/Gea2p. While it has been established that Sec7p function does not overlap with the Gea’s, the specific role of these proteins remains unclear. We show that Sec7p colocalizes poorly with the Gea’s, indicating that these proteins activate Arf on different Golgi sub-compartments. In addition, our data suggest that Sec7p mainly promotes the formation of post-Golgi transport vesicles supporting forward transport from the late Golgi while the Gea’s primarily regulate COPI-mediated retrograde traffic. This observation is consistent with published data from mammalian cells and suggests that the spatial and temporal regulation of Arf is conserved from yeast to mammals. Both Arf regulation and phosphatidylinositol 4-phosphate (PI4P) metabolism are important factors for Golgi function. Here, we show that the yeast PI4-kinase, Pik1p binds specifically to Sec7p but not Gea1p or Gea2p. Taken together, the physical interaction, the colocalization and similar transport phenotypes of the respective mutants suggests a functional link between Pik1p and Sec7p but not the Gea’s. In addition, Pik1p binds to the catalytic domain of Sec7p and could directly influence the activity of the GEF. We propose that this interaction coordinates Arf activation with PI4P production to generate a highly specific dual recognition system for the recruitment of specific effectors to the late Golgi. Besides its catalytic domain, Sec7p shares several conserved regions with other members of the BIG/GBF Arf-GEF subfamilies, including the N-terminal DCB (Dimerization/Cyclophilin Binding) domain. We show that a single point mutation in the DCB domain of Sec7p efficiently inhibits Arf activation without affecting membrane recruitment of the GEF and could interfere with a possible dimerization of the protein. We identified Cpd1p as an allele specific dosage suppressor of the Sec7p DCB domain mutation. Cpd1p and Sec7p physically interact and both proteins localize independently to the late Golgi. Increased Golgi level of Cpd1p compensates for the loss of interaction due to the mutation in the DCB domain of Sec7p. The catalytic activity of Cpd1p is important for the rescue, indicating an intriguing connection between the Arf activation cycle and ADP-ribose derivates. We also find that Cpd1p interacts with several other proteins involved in Golgi- and post-Golgi transport events. Hence, Cpd1p is a new regulator of vesicular traffic at the Golgi that could act as a scaffolding factor for Sec7p and other transport proteins.

This dissertation is an auto/ethnographic account, which examines food, close personal friendships, and community. The research combines autoethnography with ethnographic observations and personal/group interviews conducted within the Seminole Heights neighborhood of Tampa, Florida. The observations are of a weekly dinner event referred to by most attendees as Family Dinner. I am one of the founders of this event; the participants of this study are neighbors (or were at some point in time) as well as past and present attendees of the weekly dinner. The purpose of this research is to illustrate how food can be a tool to build community. In the Seminole Heights neighborhood, food acts as a communicator/builder of community and produces (a) nourishment for close personal bonds, and (b) sustainment of social capital. The nourishment and sustainment are made possible through (c) interaction. While there are many works of literature that discuss the topics of food, bonds, social capital, and interaction, little has been written on how these aspects function synergistically to create community. Using literature that speaks to food, close personal bonds, social capital, and interactions, I examine how these key aspects integrate with the ideas of community and their relationship to community building. I specifically address how people form community around the sharing of food and social interactions. In order to do so, I explore the role food plays in nourishing this community and look at how people experience and participate in community through the sharing of food. There are three areas comprising my research. 1. First, the observations describe the interactions of the community. 2. Secondly, the interviews give a sense of the weekly dinners from participants who still attend, who no longer live close enough to continue attending, and who have stopped attending for reasons other than their proximity to the neighborhood. 3. Lastly, the weaving of ethnography with autoethnography allows for a reflexive view of what these dinners mean, not only to myself, but also to those who participated in this research project. This study focuses on what constitutes community according to participants--their conceptions of community. In Addition, it illustrates the role food plays in nourishing community, and the participant's role in sustaining community.