Cloud & field is an exploration into the role the past has in the formation of a personal language and the subsequent role that language has on a personal belief system. It investigates the subjective interchangeability of the external and internal landscape. Having abandoned my childhood faith four or five years ago, the writing of this manuscript was an attempt to develop a new moral/belief system I could carry with me into the future. It is, therefore, also the beginning of an investigation into if and why a belief system is necessary.

The single hydrophone localization problem is considered. Single hydrophone localization is a special case of matched field localization where measurements from only one hydrophone are available. The time series of the pressure at the hydrophone is compared with predicted times series calculated using an ocean acoustic propagation model for many different source locations. The source location that gives the best match between the predicted time series and the measurement is assumed to be the correct source location. Single hydrophone localization algorithms from the literature are reviewed and a new algorithm is introduced. The new algorithm does not require knowledge of the source signal and does not assume the use of a particular ocean acoustic model, unlike some algorithms in the literature. Source location estimates calculated from the new algorithm are compared with ground truth using simulated ocean acoustic measurements and experimental measurements. Source location estimates calculated using other algorithms from the literature are shown for comparison. The simulated measurements use three source signals with bandwidths of 10 Hz, 100 Hz, and 200 Hz and the ocean is modeled as a Pekeris waveguide. The new algorithm estimates the source location accurately for all three source signals when several of the localization algorithms from the literature give inaccurate estimates. Gaussian white noise signals are added to the measured signals to test the impact of signal-to-noise ratio (SNR) on the algorithm. Four signal-to-noise ratios of 60 dB, 40 dB, 20 dB, and 0 dB are used. The new algorithm gives accurate source location estimates down to an SNR of 20 dB for two of the source signal bandwidths. Source location estimates using other algorithms from the literature break down at either 20 dB or 0 dB. Source location estimates are calculated using two hydrophone measurements taken at different depths in an experiment conducted near the Bahamas. The new algorithm accurately estimates the source location in both cases. In one case, only two other localization algorithms from the literature locate the source accurately. In the other case, only one other localization algorithm succeeds.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2015. / The AdS/CFT correspondence asserts a duality between non-Abelian gauge theories and quantum theories of gravity, established by the value of the gauge coupling . Gerard t'Hooft found that the large N0 limit in non-Abelian Yang-Mills gauge theories results in a planar diagram simpli cation of the topological expansion. In this dissertation, SU(2) gauge theories are written in terms of vector models (making use of collective eld theory to obtain an expression for the Jacobian), a saddle point analysis is performed, and the large N limit taken. Initially this procedure is done for gauge theories dimensionally reduced on T4 and R T3, and then attempted for the full eld theory (without dimensional reduction). In each case this results in an expression for the non-perturbative propagator. A nite volume must be imposed to obtain a gap equation for the full eld theory; directives for possible solutions to this di culty are discussed.

A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements of the degree of Master of Science. Johannesburg 2014 / Field trips to museums have been shown to achieve important learning outcomes and promote scientific literacy. However, the success of museum visits relies, in part, in the ability of teachers to effectively mediate the museum experience. A critical analysis of the literature on teacher-led field trips has shown that they are not always conducted in optimal ways and the use of worksheets is a good illustration of this dilemma. Characteristics of effective museum worksheets are described in best-practice literature; however there is a mismatch between researcher recommendations and teacher practices. Clearly there exists a need to improve teacher practice in informal educational settings. This study sought to provide insight on the ability of a teacher to follow recommendations outlined by the literature and create a best-practice worksheet. It involved two visits to the Johannesburg Zoo, with two different groups of Grade eight learners, where they were observed and audio-recorded whilst completing one of two museum worksheets. The first worksheet was designed before the teacher was aware of best-practice recommendations. The second worksheet attempted to improve on the first using researcher recommendations. The worksheets were analysed, using a worksheet analysing instrument, which showed that both contained more factors that would hinder learning and few factors that would facilitate learning. These findings suggest that, even with knowledge of best-practice recommendations, the teacher was not able to construct a worksheet that completely facilitated free-choice learning – barriers to the process included: the context of the zoo i.e. the plethora of information boards that rendered most observation-dependent questions as text-dependent; the tendency of the teacher to take advantage of the zoo setting and therefore the use of questions with a high site specificity; an increased use of orientation cues needed to reduce the ‘novelty factor’; and the use of the worksheet as an assessment tool that, therefore, provided little choice in where and how learners applied tasks asked of them. The study also investigated insight on whether or not the worksheets promoted curriculum related conversations among a group of learners. Learner conversations were coded, focusing on both nature of discourse as well as type of discourse, and analysis showed that learners cognitively and affectively engaged with worksheet tasks. However, the nature of cognitive engagement tended to be on a superficial level, suggesting learners do not have the necessary ii skills - e.g. language, argumentation and critical analysis - to initiate and conduct exploratory discussions. In view of these findings, it was concluded that it is difficult to translate best-practice recommendations into actual field trip experiences. The agenda of the teacher as well as the ability of his or her learners strongly influence how a worksheet is conducted and the worksheet is used.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 30.09.2014. / ABSTRACT In this dissertation we study the action of the one loop dilatation operator on operators with a classical dimension of order N. We consider the su(3) and su(2) sectors. The operators in the su(3) sector are constructed using three complex fields X, Y and Z, while operators in the su(2) sector are constructed from only the two complex fields Y and Z. For the operators in these sectors non-planar diagrams contribute already at the leading order in N and the planar and large N limits are distinct. Although the spectrum of anomalous dimensions in su(3) has been computed for this class of operators, previous studies have neglected certain terms which were argued to be small. After dropping these terms diagonalizing the dilatation operator reduces to diagonalizing a set of decoupled oscillators. In this dissertation we explicitly compute the terms which were neglected previously and show that diagonalizing the dilatation operator still reduces to diagonalizing a set of decoupled oscillators. In the su(2) sector the action of the one loop and the two loop dilatation operator reduces to a set of decoupled oscillators and factorizes into an action on the Z fields and an action on the Y fields. Direct computation has shown that the action on the Y fields is the same at one and two loops. In this dissertation, using the su(2) symmetry algebra as well as structural features of field theory, we give compelling evidence that the factor in the dilatation operator that acts on the Y s is given by the one loop expression, at any loop order. I hereby declare that the content of this dissertation is based on my following original works: • R. de Mello Koch, S. Graham and W. Mabanga, “Subleading corrections to the Double Coset Ansatz preserve integrability” (2013) [arXiv:1312.6230v1 [hep-th]] • R. de Mello Koch, S. Graham and I. Messamah, “Higher Loop Nonplanar Anomalous Dimensions from Symmetry” (2013) [arXiv:1312.6227v1 [hep-th]].

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 5 June 2017. / The holographic computation of extremal correlators is often frustrated by divergences. The interpretation of these divergences is incomplete. The primary goal of this study is to develop a better understanding of these divergences. Towards this end, working within the AdS/CFT correspondence we review the computation of correlators. In the field theory we review well known matrix model techniques useful to study the planar limit, as well as methods exploiting group representation theory that are useful for the computation of correlators in large N but non-planar limits. On the gravity side of the correspondence, we describe in detail the computation of two- and three point functions of a scalar field coupled to gravity on the Euclidian AdSd+1 space, three-point functions of two giant gravitons and one pointlike graviton as well as correlators of Kaluza-Klein gravitons. A key observation of this study is that extremal correlators are mapped to scattering amplitudes of particles with parallel momenta. These are naturally accompanied by involve collinear divergences. Therefore, we suggest that the divergences in the computation of extremal correlators are linked to collinear divergences. A lot more work is needed to establish this connection. / LG2017

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<p>Mobile Phone, without this we can’t think to pass a day in presence. We have found a rapid increase of mobile phone users from a few years ago till now. Day by day the modern technologies allow the mobile phone to become smaller, cheaper, and more reliable. This also creates new possibilities for applications and integrations of the classical broadcast systems and modern mobile phone technologies. One example is the FM transmitter in mobile phone. The FM transmitter in a mobile phone is a “cool” feature which allows listening to the music content in phone on a car or home radio.</p><p> </p><p>This thesis work deals with the near field characterization of FM transmitters in mobile phone applications. The RF scientists and engineers neglect the near field zone because typical RF links operate at distances of many wavelengths away where near field effects are totally insignificant. But in this work we are interested in the near field properties of the FM transmitter. We measured the field intensity at near field and estimated the field strength at the far field region at 3 meters. To measure the field intensity and the effective radiated power we used HR1 near field scanner. As this is a new measurement approach, we made the validation of this system by measuring a reference dipole antenna at 880MHz and then compare the measured results to the CST simulation results. A basic phone model of FM transmitter has been created by CST simulation and a prototype has been made which was also used as our DUT. After validation of the near field measurement system we measured our DUTs (3 models-one cable fed prototype and two active devices) with the near field system and estimate the effective radiated power and field intensity at 3 meter. Furthermore, we measured our DUTs at 3 meter with a far field measurement system with optical fiber connection. A feasible relation between field strength and measured power was defined in order to correlate the near field scanner results with the far field measurement system.</p><p> </p><p>This paper also provides a short design guide line for built in FM antennas by relating the antenna size and placement to input power and the field strength in mobile phone FM transmitter application</p>

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