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A suspended ionic solution of 1-butyl-3-methylimidazolium iron tetrachloride [BMIM][FeCl4] provides a novel medium for achieving Faraday rotation under small magnetic fields at pump wavelengths of 980nm. As verified with spectrophotometry, transmission at telecommunication wavelengths makes the solution applicable across multiple applications. A cryostation was used to measure the sample up to a 340K and under field at 600mT, the ionic sample shows the necessary temperature stability and enables compact formats suitable for potential industrial applications. With a rotation of linearly polarized light of 0.04° over a 450um path length, a full 45° rotation requires only a 50.6cm path length and with only a 0.000175°/K temperature dependence. The observation of polarization effects in real time using lock-in amplifiers, and a photo-elastic modulator demonstrates the scalability, responsiveness, and stability of the ionic liquids for photonic integration. The test set up provides a convenient way to expand the research on ionic liquid Faraday rotation materials and other Faraday liquids ideally leading to a compact in-line isolator solution.

Fluorocarbons are known to be stiffer than their hydrocarbon analogues, a property that underlines the extensive industrial application of fluorocarbon materials. Although there has been previous studies on the rotational barrier of molecules having fluorocarbon centers, a detailed systematic study is necessary to quantify flurocarbon stiffness. The molecules, Pyrene-(CF2)n-Pyrene, Pyrene-(CF2)n-F, Pyrene-(CH2)n-Pyrene and Pyrene-(CH2)n-H were therefore synthesized to enable the determination of the barrier to rotation of the carbon backbone in fluorocarbons. Conformational studies will be completed with steady-state and time-dependent emission spectroscopy.

Most studies of the pulsar magnetosphere have assumed a pure magnetic dipole in flat spacetime. However, recent work suggests that the effects of general relativity are in fact of vital importance and that realistic pulsar magnetic fields will have a significant nondipolar component. We introduce a general analytical method for studying the axisymmetric force-free magnetosphere of a slowly rotating star of arbitrary magnetic field, mass, radius, and moment of inertia, including all the effects of general relativity. We confirm that spacelike current is generically present in the polar caps (suggesting a pair production region), irrespective of the stellar magnetic field. We show that general relativity introduces a similar to 60% correction to the formula for the dipolar component of the surface magnetic field inferred from spindown. Finally, we show that the location and shape of the polar caps can be modified dramatically by even modestly strong higher moments. This can affect emission processes occurring near the star and may help explain the modified beam characteristics of millisecond pulsars.

Ce manuscrit décrit les projets de recherche qui ont porté sur l’étude de deux familles de matériaux magnétiques frustrés. La première partie traite de la réalisation d’expériences de chaleur spécifique sur le pyrochlore Sm2Ti2O7. Ces expériences ont eu lieu dans un réfrigérateur à dilution 3He-4He, à l’Université de Sherbrooke, dont le fonctionnement est décrit en amont. Ces expériences ont notamment permis l’étude de ce matériau aux températures inédites de 160 mK, où une transition magnétique du second ordre a été mise en évidence. La deuxième partie de ce mémoire porte sur l’étude des perovskites 6H, Ba3MRu2O9, à l’aide de la technique de rotation de spins de muons (mSR). Un chapitre de ce manuscrit est consacré à la description de cette technique, et les expériences ont eu lieu au centre de recherche TRIUMF, à Vancouver. Cette technique consiste à sonder le magnétisme local des matériaux placés dans un cryostat, afin de pouvoir remonter à la configuration magnétique de leur état fondamental. Contrairement à laRMN, la techinque de mSR présente le grand avantage de pouvoir sonder des matériaux avec des moments nucléaires nuls, et des expériences pouvant être réalisées sans l’application de champ externe, garantissant la conservation de l’état fondamental des matériaux étudiés. Nos expériences ont été réalisées sur quatre échantillons, avec M = La, Lu, In et Y, et bien que de précédentes études par diffraction de neutrons n’ont révélé aucune ordre magnétique à longue portée dans deux de ces composés, nos expériences ont pu mettre en évidence l’existence d’un état fondamental avec un faible moment magnétique. Enfin, l’importance des résultats de ces deux projets réside dans le fait d’avoir observé un état fondamental ordonné même si ces états n’ont pas pu être sondé à l’aide d’autres techniques, du fait des faibles moments magnétiques des matériaux étudiés.

In this thesis, we present novel methodology for emulating and calibrating computer models with high-dimensional output. Computer models for complex physical systems, such as climate, are typically expensive and time-consuming to run. Due to this inability to run computer models efficiently, statistical models ('emulators') are used as fast approximations of the computer model, fitted based on a small number of runs of the expensive model, allowing more of the input parameter space to be explored. Common choices for emulators are regressions and Gaussian processes. The input parameters of the computer model that lead to output most consistent with the observations of the real-world system are generally unknown, hence computer models require careful tuning. Bayesian calibration and history matching are two methods that can be combined with emulators to search for the best input parameter setting of the computer model (calibration), or remove regions of parameter space unlikely to give output consistent with the observations, if the computer model were to be run at these settings (history matching). When calibrating computer models, it has been argued that fitting regression emulators is sufficient, due to the large, sparsely-sampled input space. We examine this for a range of examples with different features and input dimensions, and find that fitting a correlated residual term in the emulator is beneficial, in terms of more accurately removing regions of the input space, and identifying parameter settings that give output consistent with the observations. We demonstrate and advocate for multi-wave history matching followed by calibration for tuning. In order to emulate computer models with large spatial output, projection onto a low-dimensional basis is commonly used. The standard accepted method for selecting a basis is to use n runs of the computer model to compute principal components via the singular value decomposition (the SVD basis), with the coefficients given by this projection emulated. We show that when the n runs used to define the basis do not contain important patterns found in the real-world observations of the spatial field, linear combinations of the SVD basis vectors will not generally be able to represent these observations. Therefore, the results of a calibration exercise are meaningless, as we converge to incorrect parameter settings, likely assigning zero posterior probability to the correct region of input space. We show that the inadequacy of the SVD basis is very common and present in every climate model field we looked at. We develop a method for combining important patterns from the observations with signal from the model runs, developing a calibration-optimal rotation of the SVD basis that allows a search of the output space for fields consistent with the observations. We illustrate this method by performing two iterations of history matching on a climate model, CanAM4. We develop a method for beginning to assess model discrepancy for climate models, where modellers would first like to see whether the model can achieve certain accuracy, before allowing specific model structural errors to be accounted for. We show that calibrating using the basis coefficients often leads to poor results, with fields consistent with the observations ruled out in history matching. We develop a method for adjusting for basis projection when history matching, so that an efficient and more accurate implausibility bound can be derived that is consistent with history matching using the computationally prohibitive spatial field.

Gaze direction and head rotation are powerful cues that inform humans about another person's attention, intentions and even emotion. Previous research has focused on understanding how people make judgements about individual faces in direct view. However in everyday life, people are often presented with groups of faces and need to judge where the attention of that group is directed, such as in group conversations or when giving presentations. This thesis presents research whose aim is to better understand how gaze direction and head rotation are perceived in the visual periphery and in groups. First, observers' perception of gaze deviation in the visual periphery was tested, using psychophysical methods and modelling. The results showed that observers' ability to judge gaze perception is severely limited, and that observers' judgements are severely biased by head rotation in the visual periphery. Second, observers' ability to perceive the average gaze or head direction of a group of spatially distributed faces was investigated. This was done using equivalent noise analysis, a technique which gives estimates for observers' internal noise (how certain they are in their judgements of any individual face) and their effective sample size (how many faces they are able to combine into their average). The findings revealed that head rotation was averaged with less uncertainty and greater effective sample size than gaze deviation, suggesting that observers can more precisely and efficiently pool information about head rotation than gaze. Finally, averaging of heads and gaze stimuli presented in temporal sequences was analysed using the same equivalent noise technique and compared to spatial averaging. In sequences, the differences in processing between head and gaze direction disappear, suggesting that poor peripheral perception of gaze is the limit on our averaging of gaze cues.

by Su, Shi Chun = 宇宙微波背景各向異性的非高斯特性與旋轉宇宙的規範 / by 蘇士俊. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 78-83). / Abstracts in English and Chinese. / by Su, Shi Chun = Yu zhou wei bo bei jing ge xiang yi xing de fei Gaosi te xing yu xuan zhuan yu zhou de gui fan / by Su Shijun. / Chapter 1 --- Review of Cosmic Microwave Background Anisotropies --- p.1 / Chapter 1.1 --- Robertson-Walker metric --- p.1 / Chapter 1.2 --- Cosmological Perturbation --- p.4 / Chapter 1.2.1 --- Scalar-Vector-Tensor Decomposition --- p.6 / Chapter 1.2.2 --- Gauge Transformations --- p.8 / Chapter 1.2.3 --- Scalar Perturbation --- p.8 / Chapter 1.3 --- Sachs-Wolfe Effect --- p.9 / Chapter 1.4 --- Spectrum of CMB Anisotropies --- p.11 / Chapter 1.4.1 --- Rotation Transformation of Spherical Harmonics --- p.14 / Chapter 1.5 --- Contaminations of the CMBA --- p.16 / Chapter 1.5.1 --- The Internal Linear Combination Method --- p.17 / Chapter 2 --- Review of Models of Rotating Universe --- p.22 / Chapter 2.1 --- Godel's Model of a Rotating Universe --- p.23 / Chapter 2.2 --- Bianchi Models of a Rotating Universe --- p.24 / Chapter 2.3 --- Constraints on the Rotation of our Universe --- p.26 / Chapter 3 --- Study of Non-Gaussian Properties of the CMB Anisotropies --- p.31 / Chapter 3.1 --- Methodology --- p.32 / Chapter 3.2 --- Suspicious Anomalies against the IGH --- p.33 / Chapter 3.3 --- Verifications of the Suspicious Anomalies --- p.37 / Chapter 3.3.1 --- Different Cleaning Methods --- p.37 / Chapter 3.3.2 --- Effects of the Foreground Contaminations --- p.39 / Chapter 3.4 --- Further Study and Discussion --- p.52 / Chapter 3.5 --- Conclusions --- p.56 / Chapter 4 --- CMB Constraint on the Rotation of the Universe --- p.57 / Chapter 4.1 --- The Einstein Field Equations with Rotational Perturbations --- p.58 / Chapter 4.2 --- Analytic Solutions of the EFEs for the Rotating Universe --- p.63 / Chapter 4.3 --- The Sachs-Wolfe Effects up to Second-Order due to the Rotation --- p.65 / Chapter 4.4 --- Constraints on Our Model --- p.69 / Chapter 4.5 --- Discussion --- p.72 / Chapter 4.6 --- Conclusions --- p.75 / Chapter 5 --- Summary of the Thesis --- p.76 / Bibliography --- p.78

Typewritten copy Includes bibliographical references The measurement of soil moisture in situ is called Part A; The study of soil moisture changes under a simple crop rotation is called Part B. Evaluates the Bouyoucos electrical resistance method of measuring soil moisture in situ; and studies the soil moisture under a simple crop rotation. Has been the subject of 2 papers entiled: Techniques associated with the use of gypsum block soil moisture meters / Aitchinson, Butler and Gurr; and, Gypsum block moisture meters as instruments for the measurement of tension in soil water / Aitchinson and Butler. The papers are attached. Part A includes a brief summary and discussion of these papers