Dissertations / Theses on the topic 'Parameter Interactions'

In this thesis, a leading-order QCD analysis of structure functions in neutrinonucleon interactions is performed. From the CCFR nucleon structure function data, the QCD parameter Lambda has been extracted. This measurement also corresponds to a measurement of the strong coupling constant. Two fits to the data have been performed, the nonsinglet-only fit and the singlet-nonsinglet combined fit. The result for Lambda was found to be 289 +62 ¡
59 §
76 MeV, where the errors are statistical and systematical, respectively. This result is compared to the world-wide measurements of this quantity. In order to verify the agreement, also the logarithmic slopes of the QCD model and the structure function data are calculated and compared.

In traditional optimization approaches the interaction of parameters associated with a problem is not a significant issue, but in the domain of Evolutionary Multi-Objective Optimization (EMOO) traditional genetic algorithm approaches have difficulties in optimizing problems with parameter interactions. Parameter interactions can be introduced when the search space is rotated. Genetic algorithms are referred to as being not rotationally invariant because their behavior changes depending on the orientation of the search space. Many empirical studies in single and multi-objective evolutionary optimization are done with respect to test problems which do not have parameter interactions. Such studies provide a favorably biased indication of genetic algorithm performance. This motivates the first aspect of our work; the improvement of the testing of EMOO algorithms with respect to the aforementioned difficulties that genetic algorithms experience in the presence of para meter interactions. To this end, we examine how EMOO algorithms can be assessed when problems are subject to an arbitrarily uniform degree of parameter interactions. We establish a theoretical basis for parameter interactions and how they can be measured. Furthermore, we ask the question of what difficulties a multi-objective genetic algorithm experiences on optimization problems exhibiting parameter interactions. We also ask how these difficulties can be overcome in order to efficiently find the Pareto-optimal front on such problems. Existing multi-objective test problems in the literature typically introduce parameter interactions by altering the fitness landscape, which is undesirable. We propose a new suite of test problems that exhibit parameter interactions through a rotation of the decision space, without altering the fitness landscape. In addition, we compare the performance of a number of recombination operators on these test problems. The second aspect of this work is concerned with developing an efficient multi-objective optimization algorithm which works well on problems with parameter interactions. We investigate how an evolutionary algorithm can be made more efficient on multi-objective problems with parameter interactions by developing four novel rotationally invariant differential evolution approaches. We also ask whether the proposed approaches are competitive in comparison with a state-of-the-art EMOO algorithm. We propose several differential evolution approaches incorporating directional information from the multi-objective search space in order to accelerate and direct the search. Experimental results indicate that dramatic improvements in efficiency can be achieved by directing the search towards points which are more dominant and more diverse. We also address the important issue of diversity loss in rotationally invariant vector-wise differential evolution. Being able to generate diverse solutions is critically important in order to avoid stagnation. In order to address this issue, one of the directed approaches that we examine incorporates a novel sampling scheme around better individuals in the search space. This variant is able to perform exceptionally well on the test problems with much less computational cost and scales to very high decision space dimensions even in the presence of parameter interactions.

This paper presents a numerical model for the evaluation of the actual torque in Gerotor units. The model consists of two major modules: the pre-processor module and the HYGESim module. The preprocessor module consists of the geometric and the mechanical module. The geometric pre-processor module considers the CAD geometry of Gerotor with tolerances as input and it provides as output the geometric features needed to evaluate the rotor loading and the flow features. The mechanical preprocessor module evaluates the forces of interaction at the contact points between the rotors. The flow displaced by the unit is evaluated using a lumped parameter model whereas the lubricating gaps are evaluated by solving the Reynolds Equation. The main novel aspects consist of the evaluation of the frictional losses at various interfaces. An Elasto-Hydrodynamic Lubrication (EHL) approach is used to evaluate the frictional losses at the contact points between the rotors. Tests on a prototype Gerotor unit are performed for the model validation, particularly as pertains to the features of the shaft torque. Additionally, the paper comments on the distribution of the different torque loss contributions associated with the operation of the unit taken as reference.

Hintergrund und Zielstellung: Im Zuge der Intensivierung der Schweinemast kommen Atemwegsinfektionen und deren klinische Auswirkungen auf die Tiere, in Verbindung mit möglichen Wechselwirkungen zu den Umgebungsfaktoren, eine entscheidende Bedeutung für die Tiergesundheit und Wirtschaftlichkeit der Betriebe zu. Daher war es Ziel dieser Arbeit, unter Feldbedingungen festzustellen, inwieweit Korrelationen zwischen Parametern des Stallklimas, dem Nachweis potentiell pathogener Infektionserreger des Respirationstraktes, klinischem Befund der Tiere, dem Lungenbefund am Schlachtband und den Leistungsfaktoren bestehen. Material und Methoden: Über den Zeitraum von einem Jahr wurden fünf Schweinemastbetriebe in Thüringen, mit Betriebsgrößen im Bereich von 2480 bis 22 000 Mastplätzen hinsichtlich Tiergesundheit, insbesondere der Atemwegsgesundheit und Stallklima untersucht. Betriebskenndaten über Stallbau, Belegungsdichte, Lüftungs- und Heiztechnik sowie Fütterungs, -Tränke- und Impfregime wurden aufgenommen. Für die Untersuchungen wurden pro Betrieb zwei Abteile ausgewählt. Dabei lagen die betriebsabhängigen Abteilgrößen zwischen 159 bis 751 Tieren. In diesen Abteilen wurden bei einer Stichprobengröße von zehn Tieren in zwei Mastperioden, Sommer und Winter, zu jeweils drei Zeitpunkten (Vormast, Mittelmast und Endmast) 840 Blutproben entnommen und bezüglich der lungenpathogenen Erreger PRRSV, PCV 2, SIV sowie APP untersucht. PRRSV und PCV 2 betreffend, wurde sowohl auf Virus mittels in house-PCR-Untersuchungen gepoolter Proben, als auch serologisch auf Antikörper mittels ELISA untersucht. Für den Erreger SIV erfolgte eine serologische Untersuchung auf Antikörper mittels HAH sowie für APP mittels ELISA. Des Weiteren kam es in den entsprechenden Abteilen zur Durchführung stallklimatischer Messungen, wobei die Stallklimaparameter Lufttemperatur, Relative Luftfeuchte, Luftgeschwindigkeit sowie die Beleuchtungsstärke mithilfe von Geräten der Firma Testo sowie die Konzentrationen von CO2, O2, NH3und H2S mithilfe eines Multiwarn-Mehrgasmessgeräts der Firma Dräger ermittelt wurden. Gleichzeitig erfolgte eine klinische Befunderhebung in den Gruppen, mit der Bildung eines Klinikscores mit Schwerpunkt Lungengesundheit, sowie die Aufnahme der Leistungsparameter: durchschnittliche tägliche Zunahme, Mortalität der Gruppe und dem Tierbehandlungsindex, aus denen ein Leistungsscore ermittelt wurde. Im Zuge der Schlachtung wurden 9921 Schlachtkörper, insbesondere das Geschlinge und die Lungen, makroskopisch beurteilt und daraus ein modifizierter Organboniturscore, auf Grundlage des Organbefundindex nach Blaha gebildet. Alle Score-Bewertungen erfolgten nach Punkten und gaben somit eine Aussage zum Tiergesundheitsstatus der Betriebe. Höhere Punktzahlen entsprachen einem schlechterem Gesundheits- bzw. Leistungsstatus. Somit konnten Wechselwirkungen zwischen den Ergebnissen der Blutuntersuchungen, den Stallklimaparametern, dem Klinik- und Leistungsscore sowie dem Organboniturscore mittels statistischer Auswertung hergestellt werden, wobei die einzelnen Bestände sowohl betriebsübergreifend als auch auf Bestandsebene untersucht wurden. Aufgrund durchgeführter Umbaumaßnahmen in drei Beständen wurde ein Vergleich alter und neuer Betriebsteile in die Betrachtungen mit einbezogen. Ergebnisse: Keiner der Betriebe wies eine vollständige Erregerfreiheit auf, was für die endemische Verbreitung der Infektionserreger, insbesondere PRRSV, PCV 2 sowie APP spricht. SIV wurde lediglich in einem Bestand nachgewiesen. Serokonversionen hinsichtlich PRRSV gingen signifikant mit vermehrtem Husten der Tiere (p = 0,027) und einer höheren klinischen Gesamtpunktzahl (p = 0,016) einher. Bei Virusnachweis zeigte sich mit p = 0,047 eine signifikant schlechtere Lungengesundheit. Hinsichtlich des Stallklimas bestand für die Parameter Temperatur, Relative Luftfeuchte, CO2 Gehalt sowie den Schadgasgehalten der Stallluft ein starker Bezug zu den unterschiedlichen Mastperioden Sommer und Winter, mit vorrangig schlechteren Werten in der Winterperiode. Diese Klimaparameter lagen oftmals über den Grenz- bzw. Regelwertbereichen, mit Auswirkungen auf die Atemwegsgesundheit. Mit Ausnahme des Parameters NH3 ergaben sich bestandsübergreifend mit p ≤ 0,01 signifikante Zusammenhänge zu den klinischen Befunden (höhere Teilpunkzahlen Lungengesundheit korrelieren mit ρ = 0,250 zum CO2-sowie mit ρ = 0,222 zum H2S-Gehalt der Stallluft, negativ mit ρ = −0,396 zur Temperatur) sowie NH3 inbegriffen (mit einer Korrelation von ρ = 0,401) zu den Pneumoniebefunden. Ebenfalls bestandsübergreifend zeigte sich ein signifikanter Zusammenhang zwischen der Infektion von APP (p = 0,038) sowie PRRSV (p = 0,001) und einer erhöhten Anzahl an Pleuritiden. Des Weiteren zeigten sich mit einer Signifikanz von p ≤ 0,01 in Verbindung mit verstärkten klinischen Symptomen auch signifikant mehr makroskopisch sichtbare Pneumonien bei der Schlachtung (Korrelation der Gesamtpunktzahl Klinik mit ρ = 0,297). Bestandsabhängig wurden beim Vorhandensein multipler Erregerspektren im Betrieb erhöhte Lungenbefunde ermittelt. Beziehungen der Klima- und Klinikparameter sowie der Lungenbefunde zu den Leistungsparametern, konnten nur in geringem Maße festgestellt werden. So wurden beispielsweise keine Korrelationen zwischen den Schadgasparametern und der durchschnittlichen Masttagszunahme festgestellt. Hier scheint der genetische Aspekt einen starken Einfluss zu besitzen. Schlussfolgerungen: Anhand der Untersuchungen konnten sowohl einzelbetrieblich als auch betriebsübergreifend Signifikanzen zwischen den einzelnen Parametern festgestellt werden. Die gegenseitige Beeinflussung und Abhängigkeit aller Faktoren ist jedoch immer herdenabhängig und variiert, je nach Bestandsdynamik.

We present the new framework based on BFKL and DGLAP evolution equations in which the leading in(Q(_2)) and in(l/x) terms are treated on equal footing. We introduce a pair of coupled integro-difFerential equations for the quark singlet and the unintegrated gluon distribution. The observable structure functions are calculated using high energy factorisation approach. We also include the sub-leading in (l/x) effects via consistency constraint. We argue that the use of this constraint leads to more stable solution to the Pomeron intercept than that based on the NLO calculation of the BFKL equation alone and generates resummation to all orders of the major part of the subleading in (l/x) effects. The global fit to all available deep inelastic data is performed using a simple parametrisation of the non-perturbative region. We also present the results for the longitudinal structure function and the charm component of the F(_2) structure function. Next; we extend this approach to the low Q(^2) domain. At small distances we use the perturbative approach based on the unified BFKL/DGLAP equations and for large distances we use Vector Meson Dominance Model and, for the higher mass qq states, the additive quark approach. We show the results for the total cross section and for the ratio of the longitudinal and transverse structure functions. Finally, we calculate the dijet production and consider the decorrelation effects in the azimuthal distributions caused by the diffusion in the transverse momentum k(_r) of the exchanged gluon. Using the gluon distribution which is fixed by the fit to the DIS data we are able to make absolute predictions. We show the results for the dF(_r)/dɸ, the total cross section and also the distributions in Q(^2) as well as in the longitudinal momentum fraction of the gluon. Our theoretical predictions are confronted with the measurements made using ZEUS detector at HERA.

Synthese du polydimethylsiloxane etudie et etude de l'hydrosilation se produisant au cours de la reticulation en solution semidiluee, relation entre la longueur de correlation et la concentration. Interactions a trois corps dans le styrene, solvant theta du pdmsi

Etude par rmn, de l'ordre et de la dynamique moleculaire des phases lyotropes de systemes binaires agent de surface a double chaine/eau: parametres d'ordre eleves, probabilites conformationelles, temps de correlation des mouvements moleculaires tres anisotropes en fonction de la tete polaire (phosphate ou ammonium); faible influence de la longueur de la chaine. Etude de l'ordre et de la dynamique de petites molecules en solution dans le systeme dibutylphosphate de sodium/eau en phase lamellaire: influence importante du caractere hydrophile ou hydrophobe du solute. Localisation des solutes non complexants dans le cristal liquide d'apres la relaxation induite par un ion paramagnetique

Ultrasound acoustic energy transfer (UAET) is an emerging contactless technology that offers the capability to safely and efficiently power sensors and devices while eliminating the need to replace batteries, which is of interest in many applications. It has been proposed to recharge and communicate with implanted medical devices, thereby eliminating the need for invasive and expensive surgery and also to charge sensors inside enclosed metal containers typically found in automobiles, nuclear power plants, space stations, and aircraft engines. In UAET, energy is transferred through the reception of acoustic waves by a piezoelectric receiver that converts the energy of acoustic waves to electrical voltage. It has been shown that UAET outperforms the conventional CET technologies that use electromagnetic waves to transfer energy, including inductive coupling and capacitative coupling. To date, the majority of research on UAET systems has been limited to modeling and proof-of-concept experiments, mostly in the linear regime, i.e., under small levels of acoustic pressure that result in small amplitude longitudinal vibrations and linearized piezoelectricity. Moreover, existing models are based on the "piston-like" deformation assumption of the transmitter and receiver, which is only accurate for thin disks and does not accurately account for radiation effects. The linear models neglect nonlinear effects associated with the nonlinear acoustic wave propagation as well as the receiver's electroelastic nonlinearities on the energy transfer characteristics, which become significant at high source strengths. In this dissertation, we present experimentally-validated analytical and numerical multiphysics modeling approaches aimed at filling a knowledge gap in terms of considering resonant acoustic-piezoelectric structure interactions and nonlinear effects associated with high excitation levels in UAET systems. In particular, we develop a reduced-order model that can accurately account for the radiation effects and validate it by performing experiments on four piezoelectric disks with different aspect ratios. Next, we study the role of individual sources of nonlinearity on the output power characteristics. First, we consider the effects of electroelastic nonlinearities. We show that these nonlinearities can shift the optimum load resistance when the acoustic medium is fluid. Next, we consider the nonlinear wave propagation and note that the shock formation is associated with the dissipation of energy, and as such, shock formation distance is an essential design parameter for high-intensity UAET systems. We then present an analytical approach capable of predicting the shock formation distance and validate it by comparing its prediction with finite element simulations and experimental results published in the literature. Finally, we experimentally investigate the effects of both the nonlinearity sources on the output power characteristics of the UAET system by considering a high intensity focused ultrasound source and a piezoelectric disk receiver. We determine that the system's efficiency decreases, and the maximum voltage output position drifts towards the source as the source strength is increased.
Doctor of Philosophy
Advancements in electronics that underpinned the development of low power sensors and devices have transformed many fields. For instance, it has led to the innovation of implanted medical devices (IMDs) such as pacemakers and neurostimulators that perform life-saving functions. They also find applications in condition monitoring and wireless sensing in nuclear power plants, space stations, automobiles and aircraft engines, where the sensors are enclosed within sealed metal containers, vacuum/pressure vessels or located in a position isolated from the operator by metal walls. In all these applications, it is desired to communicate with and recharge the sensors wirelessly. Such a mechanism can eliminate the need for invasive and expensive surgeries to replace batteries of IMDs and preserve the structural integrity of metal containers by eliminating the need for feed through wires. It has been shown that ultrasound acoustic energy transfer (UAET) outperforms conventional wireless power transfer techniques. However, existing models are based on several assumptions that limit their potential and do not account for effects that become dominant when a higher output power is desired. In this dissertation, we present experimentally validated numerical and theoretical investigations to fill those knowledge gaps. We also provide crucial design recommendations based on our findings for the efficient implementation of UAET technology.

New railway lines are continuously being constructed and existing lines are upgraded. Hence, there is a need for research directed towards efficient design of the supporting structures. Increasingly advanced calculation methods can be motivated, especially in projects where huge savings can be obtained from verifying that existing structures can safely support increased axle loads and higher speeds. This thesis treats the dynamic response of bridges under freight and passenger train loads. The main focus is the idealisation of the train load and its implications for the evaluation of the vertical bridge deck acceleration. To ensure the running safety of train traffic at high speeds the European design codes set a limit on the vertical bridge deck acceleration. By considering the train–bridge interaction, that is, to model the train as rigid bodies on suspension units instead of constant moving forces, a reduction in bridge response can be obtained. The amount of reduction in bridge deck acceleration is typically between 5 and 20% for bridges with a span up to 30 m. The reduction can be higher for certain train–bridge systems and can be important also for bridge spans over 30 m. This thesis aims at clarifying for which system parameter combinations the effect of train–bridge interaction is important. To this end, a thorough literature survey has been performed on studies in train–track–bridge dynamics. The governing parameters in 2D train–bridge systems have been further studied through a parameter screening procedure. The two-level factorial methodology was applied to study the effect of parameter variations as well as the joint effect from simultaneous changes in several parameters. The effect of the choice of load model was thus set in relation to the effect of other parameter variations. The results show that resonance can arise from freight train traffic within realistic speed ranges (< 150 km/h). At these resonance peaks, the reduction in bridge response from a train–bridge interaction model can be considerable. From the screening of key parameters it can furthermore be concluded that the amount of reduction obtained with a train–bridge interaction model depends on several system parameters, both for freight and passenger train loads. In line with the European design code’s guidelines for dynamic assessment of bridges under passenger trains an additional amount of damping can be introduced as a simplified way of taking into account the reduction from train–bridge interaction. The amount of additional damping is today given as function of solely the bridge span length, which is a rough simplification. The work presented in this thesis supports the need for a refined definition of the additional damping.
Nya järnvägslinjer byggs kontinuerligt och befintliga linjer uppgraderas. Det finns därför ett behov av forskning inriktad på effektiv design av de bärande konstruktionerna. Alltmer avancerade beräkningsmetoder kan vara motiverade, särskilt i projekt där stora besparingar kan erhållas från att verifiera att befintliga konstruktioner kan bära ökade axellaster och högre hastigheter. Föreliggande avhandling behandlar broars dynamiska respons under belastning av gods- och passagerartåg. Huvudfokus är att studera modelleringsalternativ för tåglasten och vilka konsekvenser de har för utvärderingen av brobanans vertikala acceleration. För att garantera trafiksäkerhet vid höga tåghastigheter definierar de europeiska normerna en maximalt tillåten vertikal acceleration i brobanan. Genom att beakta tåg-bro-interaktion, där tågkomponenterna modelleras som avfjädrade stela kroppar istället för konstanta punktlaster, kan en minskning av brons respons erhållas. Reduktionen av brobanans acceleration är typiskt mellan 5 och 20% för broar med en spännvidd på upp till 30 m. Minskningen kan vara högre för vissa tåg-brosystem och kan vara viktigt också för spännvidder över 30 m. Denna avhandling syftar till att klargöra för vilka kombinationer av tåg-broparametrar effekten av tåg-bro-interaktion är viktig. I detta syfte har en omfattande litteraturstudie genomförts inom området tåg-spår-brodynamik. De styrande parametrarna i 2D tåg-brosystem har studerats vidare i en parameterstudie. Två-nivå faktorförsök har tillämpats för att studera effekten av parametervariationer samt den ytterligare effekten av samtidiga förändringar i flera parametrar. Effekten av valet av lastmodell sattes därmed i relation till effekten av andra parametervariationer. Resultaten visar att resonans kan uppstå från godstrafik inom ett realistiskt hastighetsintervall (< 150 km/h). Vid dessa resonanstoppar kan en betydande minskning av broresponsen erhållas med en tåg-bro-interaktionsmodell. Från studien av nyckelparametrar kan man vidare dra slutsatsen att reduktionen som erhålls med en tåg-bro-interaktionsmodell beror på flera systemparametrar, både för gods- och passargerartåg. Enligt de europeiska normernas rekommendationer för dynamisk kontroll av broar för passagerartrafik kan en ökad brodämpning introduceras som ett förenklat sätt att ta hänsyn till minskningen från tåg-bro-interaktion. Mängden tilläggsdämpning anges idag som en funktion av enbart brons spännvidd, vilket är en grov förenkling. Det arbete som presenteras i denna avhandling visar på behovet av en förbättrad definition av tilläggsdämpningen.

QC 20140429

The collection of biological data has been limited by instrumentation, the complexity of the systems themselves, and even the ability of graduate students to stay awake and record the data. However, increasing measurement capabilities and decreasing costs may soon enable the collection of reasonably sampled time course data characterizing biological systems, though in general only a subset of the systemâ s species would be measured. This increase in data volume requires a corresponding increase in the use and interpretation of such data, specifically in the development of system identification techniques to identify parameter sets in proposed models. In this paper, we present the results of identifiability analysis on a small test system, including the identifiability of parameters with respect to different measurements (proteins and mRNA), and propose a working definition for â biologically meaningful estimationâ . We also analyze the correlations between parameters, and use this analysis to consider effective approaches to determining parameters with biological meaning. In addition, we look at other methods for determining relationships between parameters and their possible significance. Finally, we present potential biologically meaningful parameter groupings from the test system and present the results of our attempt to estimate the value of select groupings.
Master of Science

Parameter estimation is one of the central issues in neural spatial interaction modelling. Current practice is dominated by gradient based local minimization techniques. They find local minima efficiently and work best in unimodal minimization problems, but can get trapped in multimodal problems. Global search procedures provide an alternative optimization scheme that allows to escape from local minima. Differential evolution has been recently introduced as an efficient direct search method for optimizing real-valued multi-modal objective functions (Storn and Price 1997). The method is conceptually simple and attractive, but little is known about its behaviour in real world applications. This paper explores this method as an alternative to current practice for solving the parameter estimation task, and attempts to assess ist robustness, measured in terms of in-sample and out-of-sample performance. A benchmark comparison against backpropagation of conjugate gradients is based on Austrian interregional telecommunication traffic data. (authors' abstract)
Series: Discussion Papers of the Institute for Economic Geography and GIScience

The development of models of dynamical systems behaviour is a fundamental activity in science and engineering disciplines. This thesis examines the problem of modelling a class of dynamical systems using neural networks. Existing research reveals that neural network models have been developed for lumped parameter dynamical systems; that is, systems where the variables of interest vary only over the timedomain. However, there are no adequate neural network models for distributed parameter dynamical systems; that is, systems where the variables of interest vary over some other domain, e.g. the spatial domain, in addition to the time domaln. The main goal of this research is to develop a neural network architecture for modelling distributed dynamical systems where one has limited and incomplete knowledge about the underlying behaviour of the system. The result of this research is a generic neural network architecture - the Interacting Neural Network (INN) architecture - that is capable of modelling a wide range of distributed dynamical systems. The fundamental problem associated with distributed systems which the INN architecture addresses is that of scaling. The scaling problem manifests itself when the complexity of a model increases in a manner which is unmanageable as the problem size increases. The INN architecture solves the scaling problem by using the philosophy of interacting subsystems which is a general methodology for managing complexity. The underlying principle of this methodology is to view the system as a combination of many small subsystems and to focus the modelling effort at the subsystem level rather than at the system level. The resulting models are relatively simpler, but when allowed to interact, the complex behaviour of the original system can be retrieved. The capabilities of the INN architecture are investigated by comparing its performance with other architectures on two distributed systems. First, investigations are carried out in modelling non-linear heat flow which serves as a case study to expound the capabilities of the INN architecture. Secondly, the architecture is applied to an aquifer problem to illustrate its capabilities on modelling practical problems. It is shown that the INN architecture captures the underlying behaviour of both systems, and more significantly, that the trained network can generalise spatially, wherein the same trained network can be applied to different instances of a given system. The spatial generalisation capabilities of the INN architecture is a unique and powerful result, which when used appropriately can significantly extend the usefulness of neural network models. Finally, two major factors that affect the generalisation ability of the INN architecture are investigated: (i) the effect of changing the geometry of a given system and (ii) the effect of the amount of training data available. New relationships are deduced for both factors.

Recent scientific support for the involvement of genetic locus interaction in quantitative trait variation and the widespread use of quantitative trait locus (QTL) mapping has resulted in the need to examine those aspects concurrently. Computer software was written to simulate interacting quantitative trait loci (QTLs) in plant populations. Using this software, interacting QTLs were simulated to examine effects of epistasis on the detection of QTLs and the quality of QTL parameter estimates. Simulations involved doubled haploid populations exhibiting two non-epistatic traits and seven epistatic traits, each trait at four levels of heritability. Detection efficiency of QTL main and interaction effects decreased with decreasing heritability. At a given level of broad-sense heritability, traits differed with respect to the relative quality of main-effect detection and interaction-effect detection. Main-effect detection was notably poor for one epistatic locus that has a relatively small additive effect. Position estimates were accurate but their precision deteriorated with decreasing heritability. The quality of QTL effect estimates declined consistently with decreasing heritability, and loss in the accuracy was associated with losses in power of detection.

This thesis is concerned with two different interesting phenomena which can occur when a second parameter is introduced to a one parameter system of equations which exhibits a period-doubling cascade. The first situation we consider is when the second parameter is introduced to control the coupling strength in a system of coupled maps with dihedral symmetry which undergoes a period-doubling bifurcation. We first analyse the codimension one bifurcations which can occur in this setting - namely the period-doubling bifurcation and the symmetry-breaking bifurcation(s) which are guaranteed to exist by the Equivariant Branching Lemma - and then continue to investigate the mode interaction which occurs when the period-doubling and symmetry-breaking bifurcations coalesce. We then investigate the local solution structure in a neighbourhood of the mode interaction point for each of the possible combinations of period-doubling and symmetry-breaking bifurcations. We take a generic map and provide low order expansions for the solution branches, find parameter values at which primary and secondary bifurcations occur, investigate the existence of paths of limit points in a neighbourhood of the mode interaction, and provide bifurcation diagrams to illustrate the analysis for specific examples. The second setting we study is the transition of a (parameter-dependent) supercritical period-doubling cascade to a subcritical period-doubling cascade as a second parameter is varied. We investigate and classify the different possible supercritical period-doubling cascades and subcritical period-doubling cascades which can occur in a class of two dimensional maps. We then describe how an analysis of certain codimension 2 bifurcation points can be used to describe the mechanisms by which we might observe a supercritical period-doubling cascade being converted to a subcritical period-doubling cascade. We show that a new dynamical structure, which we call an alternating period-doubling cascade, can be observed in two dimensional maps with two parameters, and indeed that such structures can be generated as an intermediate step in the transition of a supercritical period-doubling cascade to a subcritical period-doubling cascade. The different possible alternating period-doubling cascades which can be observed in our class of maps are classified, and their dynamical behaviour is studied. Finally, we show that alternating period-doubling cascades can exhibit universal behaviour. We find two solutions to an appropriate two dimensional renormalisation operator, and obtain universal spatial and parameter scalings corresponding to each solution.

This study attempts to develop a set of parameters controlling the bead profile of deposits in powder melting, based on the spatial energy distribution of laser. Four parameters, identified as the laser material interaction parameters were used to study the bead profile formation in powder melting. The focus is put on control of the dimensional accuracy of powder deposits independently of the optical set-up and laser system. In the initial stage to understand the effect of welding parameters on the development of the fusion zone, a solid metal with homogenous and known thermal properties was used. The results indicate that for large beam diameters, typically used in cladding, power density and interaction time control the depth of penetration and beam diameter and interaction time controls the weld width. However, for small beam diameters, typically used in powder bed additive manufacturing, it was found that it is more difficult to achieve steady state conduction welds due to high conduction losses to the bulk material and rapid transition to keyhole regime. Therefore, with small beam diameters it is challenging to achieve pure conduction welds, which should guarantee good quality of deposits and low spatter. In the second part, the melting behaviour of solid material and powder for the same material type was compared. The build height in powder melting depends on layer thickness of the deposited powder and energy density, which needs to be provided to fuse the powder to the workpiece, which is equivalent to penetration in laser welding of solids. Similar to solid melting, the build width in powder melting is controlled by beam diameter and the interaction time. It was also found that with small beam diameters and large particle sizes it is more difficult to generate keyhole in the base plate, as compared to solid material. Therefore, despite the presence of spatter in the process, a full keyhole is often not generated. A set of parameters to describe the conduction welding process based on spatial distribution of laser energy has been developed. This enables achievement of a particular weld profile with various optical set-ups and potentially transfers of results between machines. However, more complex melting characteristics of powder requires some additional factors to be included to develop a similar model for powders.

Thesis (Ph. D.)--University of Oregon, 2003.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 178-181). Also available for download via the World Wide Web; free to University of Oregon users.

[Truncated abstract.] An apparatus has been built, tested and characterised with greatly increased precision and accuracy to enable spin-polarised electron impact explorations of angular momentum effects in atoms. A combination of experimental, computational and interpretative studies has revealed new phenomena. In zinc the polarisation of the radiated photons from excited and ionised-with-excited atoms was measured in terms of integrated Stokes parameters (P1, P2 and P3) and related to electron exchange and spin-orbit interaction using normalised state multipoles.

Interaction between the superstructure and foundation depends on the behavior of soil supporting the foundation. To study the behavior of interfaces, it is necessary to characterize the behavior at the interface, model constitutive relationships mathematically, and incorporate the model together with the governing equations of mechanics into numerical procedures such as the finite element method. Such an approach then can be used for solving complex problems that involve dynamic loading, nonlinear material behavior, and the presence of water, leading to saturated interfaces. In this dissertation, a general model, called the Disturbed State Concept constitutive model has been developed to model saturated Ottawa sand-Concrete interface and saturated Nevada sand. In the DSC, the material is assumed to transform continuously from the relative intact state to the fully adjusted state under loading. Hence the observed response of the material is expressed in terms of response of relatively intact and fully adjusted states. The DSC model is a unified approach and allows for elastic and plastic strains, damage, and softening and stiffening. The model parameters for saturated Ottawa sand-Concrete interface and saturated Nevada sand are evaluated using data from laboratory tests and are used for the verification of DSC model. The model predictions showed satisfactory correlation with the test results. In this dissertation, a new program based on concept of neural computing is developed to facilitate determination of interface parameters when no test data is available. The back propagation training algorithm with bias nodes is used to train the network. The program is developed in FORTRAN language using Microsoft Developer Studio. The reason for selecting FORTRAN as a programming language to develop Biased Artificial Neural Network (BANN) simulator is due to its proficiency in number crunching operations which is the core requirement of the ANN. A nonlinear dynamic finite element program (DSC-DYN2D) based on the DSC model is used to solve two problems, a centrifuge test and an axially loaded pile involving interface behavior. Overall, it can be stated that the DSC model allows realistic simulation of complex dynamic soil-structure interaction problems, and is capable of characterizing behavior of saturated interfaces involving liquefaction under dynamic and earthquake loading.

La proteine-kinase ck2 est une serine/threonine proteine-kinase ubiquiste dans le monde eucaryote. Elle se compose de deux sous-unites catalytiques differentes alpha et alpha' et d'une sous-unite regulatrice beta qui s'assemblent sous la forme d'heterotetrameres. La ck2 utilise l'atp comme le gtp, phosphoryle des proteines et peptides substrats acides et necessite une concentration extraphysiologique d'ions magnesiums pour pouvoir exhiber son activite catalytique maximale. Bien que plusieurs evidences suggerent qu'in vivo, la ck2 joue un role indispensable, aucun mode de regulation cellulaire n'a pu etre propose pour cette kinase a l'heure actuelle. Parmi les candidats susceptibles de porter une telle fonction regulatrice, les polyamines sont des composes vis-a-vis desquels de nombreuses etudes ont ete realisees. Presentes en concentrations submillimolaires, ces molecules sont capables de stimuler l'activite catalytique de la ck2 d'un facteur 10 a 20 dans des conditions de concentrations physiologiques d'ions magnesiums. Lors de ces travaux, les parametres cinetiques regissant l'activation de la ck2 en presence de polyamines, ont ete definis. L'effet de la spermine sur la ck2 a ete analyse par dichroisme circulaire. L'interaction spermine-ck2 a ete caracterisee en presence de molecules analogues de la spermine ainsi qu'en ce qui concerne le type et le nombre de liaisons mises en jeu. L'utilisation d'un analogue photoactivable de la spermine a permis d'identifier un site majeur de liaison des polyamines sur la sous-unite beta au niveau du peptide t72-m78. Deux autres sites ont ete detectes au niveau des residus h108 de cette sous-unite et l220 de la sous-unite alpha. La construction, l'expression et la purification de proteines de fusion impliquant le domaine d51-p110 de la sous-unite beta ou la sous-unite beta entiere ont permis de confirmer les resultats du marquage de photoaffinite d'une part et de definir ce domaine comme autonome et fonctionnel d'autre part. Son utilisation a conduit entre autre a la mise en evidence des domaines impliques dans l'interaction des proteines fgf-2 et ck2. Aujourd'hui, la poursuite de ce travail par une approche cellulaire pourrait permettre d'apporter des elements de reponse quant a l'existence d'un role de regulateurs physiologiques joue par les polyamines vis-a-vis de la ck2

Gasoline spills are sources of groundwater contamination. In the event of a spill, timely remediation efforts can advert most of the potential groundwater contamination due to the immiscibility of gasoline in water. Ethanol functions as a cosolvent that can increase the solubility of gasoline in water. Therefore, the risk of groundwater contamination in the event of a fuel spill increases as the ethanol content in automobile fuels increases. This study examines the effect fuel spill size and ethanol content has on the quantities of toluene, ethylbenzene, m-xylene and o-xylene (TEMO) that dissolve into the aqueous phase at equilibrium. Laboratory experiments were preformed to determine the mass fractions of TEMO in waters that were in contact with various volumes of gasoline and ethanol. UNIFAC is a model capable of predicting the concentrations of TEMO in the aqueous phase of a gasoline-ethanol-water system at equilibrium. In this study, the generalized UNIFAC-LLE method, designed for chemical engineering applications, was used to model the laboratory experiments. New UNIFAC-LLE parameters were developed to improve the model's accuracy in predicting the solubilities of aromatic species in ethanol-water mixtures. The new UNIFAC-LLE parameters were also used to model the laboratory experiments. The modeled results were compared to the analogous laboratory experiments. The UNIFAC-LLE parameters developed in this study improved the model's accuracy in predicting the solubilities of TEMO when the aqueous ethanol mass fraction was between 0.114 and 0.431.

Kyoto University (京都大学)
0048
新制・課程博士
博士(理学)
甲第12092号
理博第2986号
新制||理||1445(附属図書館)
23928
UT51-2006-J87
京都大学大学院理学研究科物理学・宇宙物理学専攻
(主査)助教授 中家 剛, 教授 今井 憲一, 教授 西川 公一郎
学位規則第4条第1項該当

Dispersing co-crystals in a polymeric carrier may improve their physicochemical properties such as dissolution rate and solubility. Additionally co-crystal stability may be enhanced. However, such dispersions have been little investigated to date. This study focuses on the feasibility of dispersing co-crystals in a polymeric carrier and theoretical calculations to predict their stability. Acetone/chloroform, ethanol/water, and acetonitrile were used to load and grow co-crystals in a HPMCAS film. Caffeine-malonic acid and ibuprofennicotinamide co-crystals were prepared using solvent evaporation method. The interactions between each of the co-crystals components and their mixtures with the polymer were studied. A solvent evaporation approach was used to incorporate each compound, a mixture, and co-crystals into HPMCAS films. Differential scanning calorimetry data revealed a higher affinity of the polymer to acidic compounds than their basic counterparts as noticed by the depression of the glass transition temperature (Tg). Moreover, the same drug loading produced films with different Tgs when different solvents were used. Solubility parameter values (SP) of the solvents were employed to predict that effect on the depression of polymer Tg with relative success. SP values were more successful in predicting the preferential affinity of two acidic compounds to interact with the polymer. This was confirmed using binary mixtures of naproxen, flurbiprofen, malonic acid, and ibuprofen. On the other hand, dispersing basic compounds such as caffeine or nicotinamide with malonic acid in HPMCAS film revealed the growth of co-crystals. A dissolution study showed that the average release of caffeine from films containing caffeine-malonic acid was not significantly different to that of films containing similar caffeine concentration. The stability of the caffeine-malonic acid co-crystals in HPMC-AS was prolonged to 8 weeks at 95% relative humidity and 45°C. The theory developed in this project, that an acidic drug with a SP value closer to the polymer will dominate the interaction process and prevent the majority of the other material from interacting with the polymer, may have utility in designing co-crystal systems in polymeric vehicles

La magnéto-hydro-dynamique (MHD) est la discipline qui étudie les interactions entre les fluides conducteurs de l’électricité et les champs magnétiques. Elle intègre les phénomènes de la dynamique des fluides et du magnétisme ou électromagnétisme, mais aussi de nouveaux propres à l’interaction des 2 domaines. Les mécanismes de l’induction permettant d’agir sans contact représentent une des particularités remarquables de cette interaction. La conductivité électrique du fluide est l'une des propriétés importantes qui influe sur l’intensité des forces électromagnétiques. Les paramètres sans dimensions qui contrôlent les phénomènes sont en général au nombre de 3, ce sont les nombre de Reynolds (Re) classique en mécanique des fluides, le paramètre d’interaction (N) rapport des forces électromagnétique aux forces d’inertie et le nombre de Reynolds magnétique (Rm) rapport du temps de diffusion du champ magnétique dans le milieu au temps de convection. L’étude proposée est tournée vers l’analyse de 2 situations qui a priori présentent peu de similarité mais qui en réalité trouvent leurs justifications dans le sens qu’elle concernent toutes deux des écoulements autour d’obstacles qui se caractérisent par un sillage dont la configuration dépends notamment du nombre de Reynolds magnétique. L’analyse a été réalisée d’une manière numérique à l’aide du logiciel «Comsol »La première situation concerne l’écoulement autour d’un cylindre lorsque le champ de vitesse le champ magnétique sont parallèles à l’infini. L’analyse a porté sur le rôle de différents paramètres comme l’influence du confinement, des perméabilités magnétiques relatives du fluide et du cylindre, et du nombre de Reynolds magnétique. Dans tous les cas la configuration des sillages, et notamment de la rue de tourbillon de von Karmann, a été analysée soit en terme de nombre de Strouhal et en termes de trainées exercée par le fluide sur le cylindre. Il a notamment été démontré l’existence d’une valeur critique du paramètre d’interaction pour laquelle les tourbillons de von Karmann disparaissent et sont remplacée par 2 tourbillons qui restent attaché au cylindre. Cette valeur critique dépend des paramètres et notamment du nombre de Reynolds magnétique. Lorsque ce nombre devient élevé la valeur critique de N est augmentée les tourbillons de von karmann persistant pour des champs magnétiques élevés.Dans la deuxième partie de la thèse, la méthode d'analyse développée dans les sections précédentes a été appliquée à l'étude du système de propulsion spatiale appelé Mini-Magnétosphère Plasma Propulsion (M2P2). Le système proposé exploite l’action du vent solaire qui est un plasma d’hydrogène complètement dissocié constitué d'électrons et de protons se déplaçant à grande vitesse entre 300 et 800 km par seconde, ce vent est donc sensible à l’action de champ magnétique. La méthode se fonde sur la création d’un champ magnétique à grande échelle transporté par un plasma magnétisé par une bobine, pour former ainsi une minimagnétoshere qui dévie le vent solaire tel que le ferait une voile. Cette interaction engendre une force permettant de propulser le véhicule spatial. Bien que faible, la force exercée appliquée sur une longue periode de temps permet d’atteindre des vitesses de plusieurs dizaines de km/s. La physique du phénomène peut être comparée, toute échelle gardée, au champ magnétique terrestre qui protège la terre des vents solaires. Dans cette étude, deux aspects spécifiques ont été considérés. Le premier concerne les conditions opératoires qui permettent au plasma éjecté d'être capté par le champ magnétique, gonflant ainsi la voile. Le second concerne le calcul de la poussée exercée par le vent sur la voile
The Magneto-hydro-dynamics (MHD) is the discipline that studies the interactions between conductive fluids and applied magnetic fields. It integrates the phenomena of fluid dynamics and magnetism or electromagnetism, but also new ones specific to the interaction of the 2 domains.One of the remarkable features of this interaction is the mechanisms of induction to act without contact. One of the important properties that influence the intensity of electromagnetic forces is the electrical conductivity of the fluid. The dimensionless parameters which control the phenomena are generally 3; these are the classic Reynolds number (Re) in fluid mechanics, the interaction parameter (N) ratio of electromagnetic forces to inertia forces and the magnetic Reynolds number (Rm), ratio of the diffusion time of the magnetic field in the medium and the convection time. The proposed study is directed towards the analysis of 2 situations which a priori have little similarity but which in reality find their justifications in the sense that they both relate to flows around obstacles which are characterized by a wake whose configuration depends in particular on the magnetic Reynolds number. The analysis was performed digitally using the Finite Elements Method (FEM) with the software Comsol®. The first situation concerns the flow around a cylinder when the velocity field and the magnetic field are parallel to infinity. The analysis focused on the role of different parameters such as the influence of confinement, magnetic permeabilities relating to the fluid and the cylinder, and the magnetic Reynolds number. In all cases, the configuration of the wake, and in particular of von Karmann street, was analyzed either in terms of Strouhal number and in terms of drag exerted by the fluid on the cylinder. It has been observed in particular the existence of critical value for the interaction parameter for which the von Karmann street disappears and is replaced by 2 vortices which remain attached to the cylinder. This critical value depends in particular on the magnetic Reynolds number. When this number becomes high the critical value of N has increased the vortices of von Karmann persist for high magnetic fields.In the second part of the thesis, the analysis method developed in Part I has been applied to the study of the Space propulsion system called Mini-Magnetosphere Plasma Propulsion (M2P2). The proposed system exploits the action of the solar wind, which is a completely dissociated hydrogen plasma made up of electrons and protons moving at high speed between 300 ÷ 800 km/s, this wind is therefore sensitive to the action of field magnetic. The method is based on the creation of a large-scale magnetic field transported by a plasma magnetized by a coil, to thus form a mini-magnetosphere which deflects the solar wind as a sail would do it.This interaction generates a force to propel the spacecraft. Although low, the force applied over a long period of time makes it possible to reach speeds of several tens of km/s. The physics of the phenomenon can be compared, any scale kept, to the terrestrial magnetic field which protects the earth from solar winds. In this study, two specific aspects were considered. The first one concerns the operative conditions that allow the ejected plasma to be captured by the magnetic field, in this way inflating the sail. The second one concerns the calculation of the thrust that the wind exerts on the sail. The analysis has been performed resorting to the non-dimensional analysis on one side to reduce the computational burden of the FEM analysis, on the other side because it made it possible to perform at the same time the analysis of the real application and a possible experimental setup on ground

The set of parameters used in the Goldstone-boson-exchange (GBE) model of quark-quark interactions by a group from the University of Graz to calculate baryon energy spectra is not optimal. A systematic approach to optimize these free parameters for a greater collection of baryons than previously treated is presented here. The baryons considered possess a physical symmetry where their constituent quarks are either made of all identical quarks or just two identical quarks. In order to calculate the various energy states of these baryons, the Faddeev method is used under the premise that three-quark interactions are modeled by an infinitely rising confinement potential. The new parameters and resulting energy calculations obtained yield better agreement with experimental data than previously achieved. In addition to providing a stronger case for the GBE model, these newfound parameters have the potential to give further insight into how quarks interact and pave the way for more advanced work in the field of three-quark problems.

Includes bibliographical references.
Flotation is widely used in the mineral processing industry to extract valuable minerals from the ore. The fundamental steps in this separation process are the attachment of hydrophobic valuable minerals to bubbles, and the subsequent accumulation of the bubble-particle aggregates in the froth phase. Processing of UG2 ore for concentration of platinum group minerals (PGMs) is a challenging task. UG2 ore contains significant amounts of chromite which is hydrophilic in nature and reports to the concentrate by means of mechanical entrainment. This is a serious problem for the downstream smelting process, which generally has a constraint of 3 chromite. In order to optimise PGM and chromite grade and recovery in UG2 processing, a number of controls are available in a plant. Among the most important are froth height, air flow rate, depressant dosage and frother concentration. On an individual level, it is expected that an increase in froth height will result in the reduction of the mechanical entrainment of chromite due to an increase in the residence time of air in the froth zone, allowing more drainage of chromite from froth to pulp. High depressant dosage is expected to enhance the grade of PGM and will reduce the recovery of naturally floatable gangue in the concentrate. However, the increase of superficial air velocity will increase the water recovery and solid recovery, thus decreasing the PGM grade with a possible increase in recovery. Increase in frother concentration increases the thickness of bubble lamella and causes more water to flow through the Plateau borders and hence increases the water recovery. Apart from the individual effect of each process parameter the interaction of same play a significant role in the solid and water recovery that affect the chromite content and the PGM grade in the concentrate.

Tire-pavement interaction noise is one of the dominant sources of vehicle noise, and one of the most significant sources of urban noise pollution. One critical generation mechanism of tire-pavement interaction noise is tire tread excitation. The tire tread contributes to the tire-pavement interaction noise mainly through two mechanisms: (1) tread block impact, and (2) the compression and expansion of the air in the tread groove at the contact patch. The tread pattern is the critical part of the tire design since it can be easily modified. Hence, the main focus of this study is to quantify the tread pattern contribution in total tire-pavement interaction noise. To achieve this goal, the noise produced by the tread pattern is separated from the total tire-pavement interaction noise. Since the tread pattern excitation is periodic with tire rotation, the noise produced by the tread is assumed to be related to the tire rotation. Hence, the order domain synchronous averaging method is used in this study to separate and quantify the tread pattern contribution to the total tire-pavement interaction noise. The experiment has been carried out using an On-Board-Sound-Intensity (OBSI) system. Five tires were tested including the Standard Reference Test Tire (SRTT). Compared to the conventional OBSI system, an optical sensor was added to the system to monitor the tire rotation. The once per revolution signal provided by the optical sensor is used to identify the noise signals associate to each revolution. In addition to the averaging method using optical signals, other data processing techniques have been investigated for separating the tread-pattern noise without utilizing the once per revolution signal. These techniques are autocorrelation analysis, a frequency domain filter, principal component analysis, and independent component analysis. In the tread-pattern noise generation, the tread profile is the most important input parameter. To characterize the tread profile, the tread pattern spectral content and air volume velocity spectral content for all the five tires are computed. Then, the tread pattern spectrum and the air volume velocity spectrum are both correlated with the separated tread-pattern noise by visual inspection of the spectra shape.
Master of Science

The rational design of novel chemotherapeutics is based upon knowledge of the intermolecular interactions between ligands and their targets, and the physical, topological and dynamic properties of those ligands within the biological environment. The pyrrolo(2,1-c)(1,4)benzodiazepine-5-ones (PBDs) are a family of sequence-selective, DNA minor groove-binding antitumour agents that inhibit transcriptional events and DNA replication. The effect of pH and salt concentrations on the conjugation rates of two PBDs with short DNA sequences were quantified by HPLC analysis. To further understand how the binding interactions of PBDs with DNA are affected by varying electrolyte conditions, computational techniques including conformational searching and molecular dynamics simulations were applied. The effect of the environment on the conformation of ligands and their target interactions was further evaluated and utilised in the design of Keap1-Nrf2 protein-protein interaction (PPI) inhibitors. Inhibition of this PPI increases the free concentration of Nrf2, a redox transcription factor which plays important roles in controlling xenobiotic and oxidative stress. Inhibitors could therefore act as cytoprotective agents in a range of diseases. A series of peptides with minor sequence modifications that interact with Keap1 were evaluated using computational approaches including: conformational searching (MacroModel), simulated annealing and molecular dynamics (Desmond). Binding poses of peptides in complex with Keap1 based on the structural information from the crystal structure of the Keap1-Nrf2 complex (PDB entry 1X2R) were predicted using several molecular docking programs (Hex, GLUE, Glide, GOLD). Finally, a series of reference crystal structures of a small molecule and peptides in complex with Keap1 were used as templates for the rational design of potential inhibitors of the Keap1-Nrf2 PPI. ‘Scaffold hopping’ (Spark) and free energy perturbation (FEP) (MCPRO) calculations were applied during the inhibitor design to provide possible replacements for key structural elements. This resulted in a virtual library of potential non-peptide inhibitors of the Keap1-Nrf2 PPI for future synthesis and evaluation.

In mammalian hearts, initiation of the heartbeat occurs in a region of specialised pacemaker cells known as the sinoatrial node (SAN). The SAN is a highly complex spatially distributed structure which displays considerable cellular heterogeneity and is subject to complex electrotonic interactions with the surrounding atrial tissue. In this study, biophysically detailed ionic models of central and peripheral SAN pacemaker cells are described. These models are able to accurately reproduce experimental recordings of the membrane potential from central and peripheral SAN tissue. These models are used to investigate frequency synchronisation of electrically coupled cardiac pacemaker cells. Based on simulation results presented, it is proposed that cellular heterogeneity in the SAN plays an important role in achieving rhythm coordination and possibly contributes to the efficient activation of the surrounding atrial myocardium. This represents an important, previously unexplored, mechanism underlying pacemaker synchronisation and cardiac activation in vivo. A spatial-gradient model of action potential heterogeneity within the SAN is then formulated using a large-scale least squares optimisation technique. This model accurately reproduces the smooth spatial variation in action potential characteristics observed in the SAN. One and two dimensional models of the intact SAN are then formulated and three proposed models of SAN heterogeneity are investigated: 1) the discrete-region model, in which the SAN consists of a compact central region surrounded by a region of transitional pacemaker cells, 2) the gradient model, in which cells of the SAN exhibit a smooth variation in properties from the centre to the periphery of the SAN, and 3) the mosaic model, in which SAN and atrial cells are scattered throughout the SAN region with the proportion of atrial cells increasing towards the periphery. Simulation results suggest that the gradient model achieves frequency entrainment more easily than the other models of SAN heterogeneity. The gradient model also reproduces action potential waveshapes and a site of earliest activation consistent with experimental observations in the intact SAN. It is therefore proposed that the gradient model of SAN heterogeneity represents the most plausible model of SAN organisation.

[EN] Computers are now present everywhere, but their potential is not fully exploited due to some lack of acceptance. In this thesis, the pen computer paradigm is adopted, whose main idea is to replace all input devices by a pen and/or the fingers, given that the origin of the rejection comes from using unfriendly interaction devices that must be replaced by something easier for the user. This paradigm, that was was proposed several years ago, has been only recently fully implemented in products, such as the smartphones. But computers are actual illiterates that do not understand gestures or handwriting, thus a recognition step is required to "translate" the meaning of these interactions to computer-understandable language. And for this input modality to be actually usable, its recognition accuracy must be high enough. In order to realistically think about the broader deployment of pen computing, it is necessary to improve the accuracy of handwriting and gesture recognizers. This thesis is devoted to study different approaches to improve the recognition accuracy of those systems. First, we will investigate how to take advantage of interaction-derived information to improve the accuracy of the recognizer. In particular, we will focus on interactive transcription of text images. Here the system initially proposes an automatic transcript. If necessary, the user can make some corrections, implicitly validating a correct part of the transcript. Then the system must take into account this validated prefix to suggest a suitable new hypothesis. Given that in such application the user is constantly interacting with the system, it makes sense to adapt this interactive application to be used on a pen computer. User corrections will be provided by means of pen-strokes and therefore it is necessary to introduce a recognizer in charge of decoding this king of nondeterministic user feedback. However, this recognizer performance can be boosted by taking advantage of interaction-derived information, such as the user-validated prefix. Then, this thesis focuses on the study of human movements, in particular, hand movements, from a generation point of view by tapping into the kinematic theory of rapid human movements and the Sigma-Lognormal model. Understanding how the human body generates movements and, particularly understand the origin of the human movement variability, is important in the development of a recognition system. The contribution of this thesis to this topic is important, since a new technique (which improves the previous results) to extract the Sigma-lognormal model parameters is presented. Closely related to the previous work, this thesis study the benefits of using synthetic data as training. The easiest way to train a recognizer is to provide "infinite" data, representing all possible variations. In general, the more the training data, the smaller the error. But usually it is not possible to infinitely increase the size of a training set. Recruiting participants, data collection, labeling, etc., necessary for achieving this goal can be time-consuming and expensive. One way to overcome this problem is to create and use synthetically generated data that looks like the human. We study how to create these synthetic data and explore different approaches on how to use them, both for handwriting and gesture recognition. The different contributions of this thesis have obtained good results, producing several publications in international conferences and journals. Finally, three applications related to the work of this thesis are presented. First, we created Escritorie, a digital desk prototype based on the pen computer paradigm for transcribing handwritten text images. Second, we developed "Gestures à Go Go", a web application for bootstrapping gestures. Finally, we studied another interactive application under the pen computer paradigm. In this case, we study how translation reviewing can be done more ergonomically using a pen.
[ES] Hoy en día, los ordenadores están presentes en todas partes pero su potencial no se aprovecha debido al "miedo" que se les tiene. En esta tesis se adopta el paradigma del pen computer, cuya idea fundamental es sustituir todos los dispositivos de entrada por un lápiz electrónico o, directamente, por los dedos. El origen del rechazo a los ordenadores proviene del uso de interfaces poco amigables para el humano. El origen de este paradigma data de hace más de 40 años, pero solo recientemente se ha comenzado a implementar en dispositivos móviles. La lenta y tardía implantación probablemente se deba a que es necesario incluir un reconocedor que "traduzca" los trazos del usuario (texto manuscrito o gestos) a algo entendible por el ordenador. Para pensar de forma realista en la implantación del pen computer, es necesario mejorar la precisión del reconocimiento de texto y gestos. El objetivo de esta tesis es el estudio de diferentes estrategias para mejorar esta precisión. En primer lugar, esta tesis investiga como aprovechar información derivada de la interacción para mejorar el reconocimiento, en concreto, en la transcripción interactiva de imágenes con texto manuscrito. En la transcripción interactiva, el sistema y el usuario trabajan "codo con codo" para generar la transcripción. El usuario valida la salida del sistema proporcionando ciertas correcciones, mediante texto manuscrito, que el sistema debe tener en cuenta para proporcionar una mejor transcripción. Este texto manuscrito debe ser reconocido para ser utilizado. En esta tesis se propone aprovechar información contextual, como por ejemplo, el prefijo validado por el usuario, para mejorar la calidad del reconocimiento de la interacción. Tras esto, la tesis se centra en el estudio del movimiento humano, en particular del movimiento de las manos, utilizando la Teoría Cinemática y su modelo Sigma-Lognormal. Entender como se mueven las manos al escribir, y en particular, entender el origen de la variabilidad de la escritura, es importante para el desarrollo de un sistema de reconocimiento, La contribución de esta tesis a este tópico es importante, dado que se presenta una nueva técnica (que mejora los resultados previos) para extraer el modelo Sigma-Lognormal de trazos manuscritos. De forma muy relacionada con el trabajo anterior, se estudia el beneficio de utilizar datos sintéticos como entrenamiento. La forma más fácil de entrenar un reconocedor es proporcionar un conjunto de datos "infinito" que representen todas las posibles variaciones. En general, cuanto más datos de entrenamiento, menor será el error del reconocedor. No obstante, muchas veces no es posible proporcionar más datos, o hacerlo es muy caro. Por ello, se ha estudiado como crear y usar datos sintéticos que se parezcan a los reales. Las diferentes contribuciones de esta tesis han obtenido buenos resultados, produciendo varias publicaciones en conferencias internacionales y revistas. Finalmente, también se han explorado tres aplicaciones relaciones con el trabajo de esta tesis. En primer lugar, se ha creado Escritorie, un prototipo de mesa digital basada en el paradigma del pen computer para realizar transcripción interactiva de documentos manuscritos. En segundo lugar, se ha desarrollado "Gestures à Go Go", una aplicación web para generar datos sintéticos y empaquetarlos con un reconocedor de forma rápida y sencilla. Por último, se presenta un sistema interactivo real bajo el paradigma del pen computer. En este caso, se estudia como la revisión de traducciones automáticas se puede realizar de forma más ergonómica.
[CAT] Avui en dia, els ordinadors són presents a tot arreu i es comunament acceptat que la seva utilització proporciona beneficis. No obstant això, moltes vegades el seu potencial no s'aprofita totalment. En aquesta tesi s'adopta el paradigma del pen computer, on la idea fonamental és substituir tots els dispositius d'entrada per un llapis electrònic, o, directament, pels dits. Aquest paradigma postula que l'origen del rebuig als ordinadors prové de l'ús d'interfícies poc amigables per a l'humà, que han de ser substituïdes per alguna cosa més coneguda. Per tant, la interacció amb l'ordinador sota aquest paradigma es realitza per mitjà de text manuscrit i/o gestos. L'origen d'aquest paradigma data de fa més de 40 anys, però només recentment s'ha començat a implementar en dispositius mòbils. La lenta i tardana implantació probablement es degui al fet que és necessari incloure un reconeixedor que "tradueixi" els traços de l'usuari (text manuscrit o gestos) a alguna cosa comprensible per l'ordinador, i el resultat d'aquest reconeixement, actualment, és lluny de ser òptim. Per pensar de forma realista en la implantació del pen computer, cal millorar la precisió del reconeixement de text i gestos. L'objectiu d'aquesta tesi és l'estudi de diferents estratègies per millorar aquesta precisió. En primer lloc, aquesta tesi investiga com aprofitar informació derivada de la interacció per millorar el reconeixement, en concret, en la transcripció interactiva d'imatges amb text manuscrit. En la transcripció interactiva, el sistema i l'usuari treballen "braç a braç" per generar la transcripció. L'usuari valida la sortida del sistema donant certes correccions, que el sistema ha d'usar per millorar la transcripció. En aquesta tesi es proposa utilitzar correccions manuscrites, que el sistema ha de reconèixer primer. La qualitat del reconeixement d'aquesta interacció és millorada, tenint en compte informació contextual, com per exemple, el prefix validat per l'usuari. Després d'això, la tesi se centra en l'estudi del moviment humà en particular del moviment de les mans, des del punt de vista generatiu, utilitzant la Teoria Cinemàtica i el model Sigma-Lognormal. Entendre com es mouen les mans en escriure és important per al desenvolupament d'un sistema de reconeixement, en particular, per entendre l'origen de la variabilitat de l'escriptura. La contribució d'aquesta tesi a aquest tòpic és important, atès que es presenta una nova tècnica (que millora els resultats previs) per extreure el model Sigma- Lognormal de traços manuscrits. De forma molt relacionada amb el treball anterior, s'estudia el benefici d'utilitzar dades sintètiques per a l'entrenament. La forma més fàcil d'entrenar un reconeixedor és proporcionar un conjunt de dades "infinit" que representin totes les possibles variacions. En general, com més dades d'entrenament, menor serà l'error del reconeixedor. No obstant això, moltes vegades no és possible proporcionar més dades, o fer-ho és molt car. Per això, s'ha estudiat com crear i utilitzar dades sintètiques que s'assemblin a les reals. Les diferents contribucions d'aquesta tesi han obtingut bons resultats, produint diverses publicacions en conferències internacionals i revistes. Finalment, també s'han explorat tres aplicacions relacionades amb el treball d'aquesta tesi. En primer lloc, s'ha creat Escritorie, un prototip de taula digital basada en el paradigma del pen computer per realitzar transcripció interactiva de documents manuscrits. En segon lloc, s'ha desenvolupat "Gestures à Go Go", una aplicació web per a generar dades sintètiques i empaquetar-les amb un reconeixedor de forma ràpida i senzilla. Finalment, es presenta un altre sistema inter- actiu sota el paradigma del pen computer. En aquest cas, s'estudia com la revisió de traduccions automàtiques es pot realitzar de forma més ergonòmica.
Martín-Albo Simón, D. (2016). Contributions to Pen & Touch Human-Computer Interaction [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/68482
TESIS

The land (or ‘terrestrial’) biosphere strongly influences the exchange of carbon, energy and water between the land surface and the atmosphere. The size of the land carbon store and the magnitude of the interannual variability of the carbon exchange make models of the land surface a vital component in climate models. This thesis addresses two aspects of land surface modelling: soil respiration and phenology modelling, using different techniques with the goal of improving model representation of land-atmosphere interaction. The release of heat associated with soil respiration is neglected in the vast majority of large-scale models but may be critically important under certain circumstances. In this thesis, the effect of this heat release is considered in two ways. Firstly, a deliberately simple model for soil temperature and soil carbon, including biological heating, is constructed to investigate the effect of thermal energy generated by microbial respiration on soil temperature and soil carbon stocks, specifically in organic soils. Secondly, the mechanism for biological self-heating is implemented in the Joint UK Land Environment Simulator (JULES), in order to investigate the impacts of the extra feedback in a complex model. With the intention of improving estimates of the parameters governing modelled land surface processes, a data assimilation system based on the JULES land surface model is presented. The ADJULES data assimilation system uses information from the derivative of JULES (or adjoint) to search for a locally optimum parameter set by calibrating against observations. In this thesis, ADJULES is used with satellite-derived vegetation indices to improve the modelling of phenology in JULES.

Tire-Pavement Interaction Noise (TPIN) becomes the main noise source contributor for passenger vehicles traveling at speeds above 40 kph. Therefore, it represents one of the main contributors to noise environmental pollution in residential areas nearby highways. TPIN has been subject of exhaustive studies since the 1970s. Still, almost 50 years later, there is still not an accurate way to model it. This is a consequence of a large number of noise generation mechanisms involved in this phenomenon, and their high complexity nature. It is acknowledged that the main noise mechanisms involve tire vibration, and air pumping within the tire tread and pavement surface. Moreover, TPIN represents the only vehicle noise source strongly affected by an external factor such as pavement roughness. For the last decade, new machine learning algorithms to model TPIN have been implemented. However, their development relay on experimental data, and do not provide strong physical insight into the problem. This research studied the correct configuration of such tools. More specifically, Artificial Neural Network (ANN) configurations were studied. Their implementation was based on the problem requirements (acoustic sound pressure prediction). Moreover, a customized neuron configuration showed improvements on the ANN TPIN prediction capabilities. During the second stage of this thesis, tire noise test was undertaken for different tires at different pavements surfaces on the Virginia Tech SMART road. The experimental data was used to develop an approach to account for the pavement profile when predicting TPIN. Finally, the new ANN configuration, along with the approach to account for pavement roughness were complemented using previous work to obtain what is the first reasonable accurate and complete tool to predict tire noise. This tool uses as inputs: 1) tire parameters, 2) pavement parameters, and 3) vehicle speed. Tire noise narrowband spectra for a frequency range of 400-1600 Hz is obtained as a result.
Master of Science
Tire-Pavement Interaction Noise (TPIN) becomes the main noise source contributor for passenger vehicles traveling at speeds above 40 kph. Therefore, it represents one of the main contributors to noise environmental pollution in residential areas nearby highways. TPIN has been subject of exhaustive studies since the 1970s. Still, almost 50 years later, there is still not an accurate way to model it. This is a consequence of a large number of noise generation mechanisms involved in this phenomenon, and their high complexity nature. It is acknowledged that the main noise mechanisms involve tire vibration, and air pumping within the tire tread and pavement surface. Moreover, TPIN represents the only vehicle noise source strongly affected by an external factor such as pavement roughness. For the last decade, machine learning algorithms, based on the human brain structure, have been implemented to model TPIN. However, their development relay on experimental data, and do not provide strong physical insight into the problem. This research focused on the study of the correct configuration of such machine learning algorithms applied to the very specific task of TPIN prediction. Moreover, a customized configuration showed improvements on the TPIN prediction capabilities of these algorithms. During the second stage of this thesis, tire noise test was undertaken for different tires at different pavements surfaces on the Virginia Tech SMART road. The experimental data was used to develop an approach to account for the pavement roughness when predicting TPIN. Finally, the new machine learning algorithm configuration, along with the approach to account for pavement roughness were complemented using previous work to obtain what is the first reasonable accurate and complete computational tool to predict tire noise. This tool uses as inputs: 1) tire parameters, 2) pavement parameters, and 3) vehicle speed.

Asymmetrically sandwiched ferromagnetic thin films display a large number of spin-orbit effects, including the Dzyaloschinsii-Moriya interaction (DMI), spin-orbit torques (SOT) and magnetoresistance (MR) effects. Their concurrence promises the implementation of interesting magnetic structures like skyrmions in future memory and logic devices. The complex interplay of various effects originating from the spin-orbit coupling and their dependencies on the microstructural details of the material system mandates a holistic characterization of its properties. In this PhD thesis, a comprehensive study of the spin-orbit effects in a chromium oxide/cobalt/platinum trilayer sample series is presented. The determination of the complete micromagnetic parameter set is based on a developed measurement routine that utilizes quasistatic methods. The unambiguous quantification of all relevant constants is crucial for the modeling of the details of magnetic structures in the system. In this context the necessity of a strict distinction of magnetic objects, that are stabilized by magnetostatics or the DMI, was revealed. Furthermore, a sample layout was developed to allow for the simultaneous quantification of the magnitudes of SOTs and MR effects from nonlinear magnetotransport measurements. In conjunction with a structural characterization, the dominating dependence of the effect magnitudes on microstructural details of the systems is concluded. Precisely characterized systems establish a solid groundwork for further investigations that are needed for viable skyrmion-based devices.

Responding to the need within the human-computer interaction field to address ubiquitous and multitasking systems more scientifically, this research extends the usefulness of a new research framework for a particular class of systems. Notification systems are interfaces used in a divided-attention, multitasking situation, attempting to deliver current, valued information through a variety of platforms and modes in an efficient and effective manner. Through review of literature and experiences with empirical dual-task perceptual studies, we recognize a lack of unifying framework for understanding, classifying, analyzing, developing, evaluating, and discussing notification systems--fundamentally inhibiting scientific growth and knowledge reuse that should help designers advance the state-of-the-art. To this end, we developed a framework (referred to as the IRC framework) for notification systems research based on a core taxonomy of critical parameters describing user goals. Next, we extend the framework, focusing on three key aspects: 1) a system description process, allowing articulation of abstract design objectives that focus on critical user requirements; 2) interface usability evaluation tools, enabling comparison of the design and user's models, while supporting generalizability of research and early identification of usability concerns; and 3) design comparison and reuse mechanisms, saving time and effort in requirements analysis and early design stages by enabling design reuse and appreciation of design progress. Results from this research include the development of tools to express IRC design models (IRCspec) and user's models (IRCresults), and the extension of the critical parameters concept. Validation studies with novice designers show sufficient assessment accuracy and consistency. Leveraging these tools that help designers express abstract, yet critical, design intentions and effects as classification and retrieval indices, we develop a repository for reusable design knowledge (a claims library). Responding to challenges of design knowledge access that we observed through initial user testing, we introduce a vision for an integrated design environment (LINK-UP) to operationalize the IRC framework and notification systems claims library in a computer-aided design support system. Proof-of-concept testing results encourage the thought that when valuable design tools embody critical parameters and are coupled with readily accessible reusable design knowledge, interface development will improve as a scientific endeavor.
Ph. D.

Pendant les dernières décennies les chercheurs ont étudié l'interaction entre des inclusions membranaires avec leur environnement et plus particulièrement avec la bicouche lipidique. On trouve dans la litérature beaucoup d'études théoriques et de simulations numériques sur ce sujet mais très peu d'expériences ont été menés là-dessus.Nous avons effectué des études systématiques afin de quantifier le potentiel d'interaction entre deux types d'inclusions au sein de la même couche et entre des couches adjacentes de plusieurs types de membranes ceci en variant surtout la concentration de particules dopantes, mais aussi d'autres paramètres pertinents : le type de tensioactif, l'épaisseur de la membrane, le contenu en cholestérol, la température, le degré d'hydratation. Pour cette fin nous avons utilisé la diffraction des rayons X aux petits angles et nous avons constaté que le potentiel d'interaction peut être décrit par une exponentielle décroissante en fonction de la concentration et de la température d'inclusion et qu'il dépend largement de la teneur en cholestérol et du degré d'hydratation.D'autre part, nous avons étudié l'effet de la gramicidine, un peptitde membranaire, sur l'ordre local des chaînes acyles de lipides et de tensioactifs. Cette étude a été menée en utilisant deux techniques différentes: en premier lieu la résonnance magnétique nucléaire, (DROSS-NMR) qui permet de détecter le changement d'ordre dans l'orientation des chaînes acyles, et en second lieu par diffraction des rayons X aux grands angles afin de déterminer le changement d'ordre dans la position des chaînes acyles. Nous avons trouvé que le dopage de la gramicidine dans les membranes rigidifie les chaînes acyles et dans un cas aussi les têtes polaires et en plus induit une modification de l'ordre local de ces chaînes
For years scientists have been studying the interaction of membrane inclusions with their environment and more particularly with the lipid bilayer.This field has been based on theoretical approaches and numerical simulation and lack experiments.We performed systematic studies in order to quantify the interaction potential between two types of inclusions within the same layer and between adjacent layers in several kinds of membranes and tried to elucidate the influence of the relevant parameters: the type of lipids or surfactants, the cholesterol content, the hydration degree, the type of inclusions and the membrane thickness using small-angle X-ray scattering. We found that the interaction potential can be described by a decreasing exponential as a function of inclusion concentrations and temperature and depends largely on the cholesterol content and hydration degree.On the other hand, we also studied the effect of the peptide inclusions on the local order of lipid and surfactant acyl chains using two different techniques: DROSS-NMR technique to detect the changes in the orientational order and WAXS technique to detect the changes in the positional order of the acyl chains. We found that inserting these peptides inclusions within the membrane rigidifies the acyl chains and sometimes even the headgroups and modifies their local order

This thesis is a part of the French national project called MACAO (Modélisation Avancée de Composants Aéronautiques et Outils associés). In collaboration with Messier-Dowty company (a landing gears manufacturer), the thesis has contributed to better understand the actual literature studies in the field of aircraft tyre-road interaction modelling and therefore, to help making an optimal choice of model for a specifie application. The objectives have been to propose models for representing the tyre behaviour on the ground with respect to the aircraft run types. Physical oriented models are preferred. To complete this study, a literature survey of the previous researches in tyre modelling for steady­state responses is first carried out. Then, based on the main factors playing an important role in tyre modelling, it is proposed a classification for the physical and the semi-empirical models, which are also investigated. Based on this classification, the study requirements and the measurement data constraints, an a priori choice of suitable models are studied. A further investigation of the tyre deformation at pure lateral slip is carried out. It has allowed to physically describe the mechanism of generation of the longitudinal component of the tyre force at pure lateral slip. This force is refened as induced longitudinal force. By taking this force into consideration, it has been possible to explain why the self-aligning moment can drop to zero before the tyre gets to full sliding at pure lateral slip. Besides, the sensitivity analysis is proposed as a means for determining the parameters that have most influence on the model output and thus, are responsible for the output uncertainty.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2017.
The purpose of the present study was to apply data collected monthly over a 6-year period along the almost 200 km long St. Helena Bay Monitoring Line in the Southern Benguela upwelling system to investigate co-variation between an upwelling index calculated from nearby wind records and physical and chemical properties along the transect. The extent to which the well-documented seasonal upwelling cycles is manifested at the surface along an inshore-offshore variation was investigated in the context of implications for the validity of remote sensing as a monitoring tool in this ocean area and to improve understanding of the physical drivers of biological processes in St. Helena Bay. This study shows that surface temperature and nutrient concentrations exhibit very poor seasonality and weak correlation with the upwelling index. This is, despite clear evidence for spatial inshore-offshore gradients in temperature, nutrients, and chlorophyll-a, consistent with an upwelling regime. The upper ocean temperature gradient shows a much better correspondence to the upwelling index but at the same time demonstrates that surface heating, and not vertical mixing related to upwelling, controls the upper ocean temperature gradient. In this study linear lagged correlations were also examined and discussed to gain insight into the effect upwelling has on the surface waters in St. Helena Bay with the view of determining the following: (1) Does upwelling lead to an increase or decrease of the water properties? (2) What is the characteristic lag between an upwelling event and its effect on these water properties? (3) Is the effect and/or lag different for the different seasons? and (4) Is the effect and/or lag different for stations inside the bay and those outside the bay?. A combination of surface turbulent cooling through upwelling occurred after a lag of 8 to 10 days in winter and early summer, but less than half in late summer, similar to results obtained with salinity. However, the rest of the salinity results fit in poorly with the temperature results. The only significant correlation obtained with the inshore stations during late summer is the inexplicable positive correlation at a lag of 7 days. For all three seasons virtually none of the oxygen results fit the expected pattern. All three nutrients showed a more positive correlation coefficient and significance than the negative ones. Significant negative correlations occurred mainly during late summer at lags of 7 to 9 days caused by planktonic depletion of nutrients. Also, in this season, significant positive correlations between south-north wind and nutrients only occurred at short lags. This observation supports the earlier temperature-based conclusion that the influence of upwelling develops most rapidly at this time of the year. A rapid increase in chlorophyll-a levels followed by nutrient enrichment of the surface layers are evident. iii The results suggest that remote sensing techniques would be inadequate tools to monitor upwelling events in the Southern Benguela. Secondly, the incidence of phytoplankton blooms is more likely triggered by stratified conditions associated with surface heating than relaxation of upwelling winds. Finally, these results also emphasise the importance of validating lagged outputs against real-time measurements in supporting a simpler hydrological model in narrowing down these significant uncertainties.

Les composes nitroaromatiques possedent, comme l'oxygene mais a des degres divers, des proprietes radiosensibilisatrices in vitro. Ces composes sont aussi des antibiotiques envers des cellules hypoxiques ou anoxiques. Ces deux proprietes pharmacologiques sont reliees a la reduction des arno#2 par des reactions a un ou deux electrons, induites soit par des radiations, soit par des reactions biochimiques catalysees ou non par une nitro-reductase, ainsi qu'au potentiel d'oxydoreduction de arno#2. Dans le present travail, on a etudie par la methode de radiolyse pulsee, les deux premieres etapes de la reduction de arno#2, conduisant au derive nitroso toxique arno. On a etudie les cinetiques des reactions de formation et de dismutation du radical nitro et ses ionisations acide-base. On a pu etablir, sur onze composes nitro-heterocycliques, des correlations fortes entre des constantes cinetiques de la dismutation du radical nitro intermediaire et plusieurs proprietes pharmacologiques. L'etude, par radiolyse pulsee, de l'interaction du radical nitro avec divers extraits cellulaires ou enzymes pures, ayant une activite de nitro-reductase, d'oxygene-reductase, de superoxyde dismutase ou de nitrite-reductase, conduit a conclure a l'absence d'une activite de nitro-radical dismutase. Les interactions de arno#2 et du radical nitro avec deux oxygene-reductases a cuivre, la laccase et la ceruloplasmine ont ete plus particulierement etudiees. On detecte un transfert d'electron entre le radical nitro et le site a cuivre de type i, mais ces enzymes n'ont pas d'activite de nitro-reductase ni de nitro-radical dismutase

The first order ternary interaction parameters of bismuth in molten copper containing either iron, arsenic or antimony have been evaluated using a pseudo equilibrium process at temperatures between 1398 K and 1473 K. The isopiestic distribution technique developed in this investigation yielded the following results: εFeBi=[(1.11x10⁶)/T]- 754 εAsBi=[(4.4x10⁴)/T]-24 εSbBi=-11 These results, coupled with other activity data, have been used to calculate the isoactivity curves for each constituent in the copper rich corner of each ternary system. The basis for the ternary interactions associated with εFeBi, εAsBi and εSbBi are also discussed.