Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Electromagnetic shielding plays a significant role in the protection of electronic equipment. Its application is essential for mitigating radio-frequency interference for the Karoo Array Telescope (MeerKAT) project in the Karoo region of the Northern Cape. In this context, time-domain (TD) methodology for small enclosure shielding effectiveness (SE) is developed using a reverberated environment technique. Interest revolves around measurement time speed-up and an extended SE response which covers the under-moded condition of small enclosures. Recommended IEC standard 61000-4-21 [1] e ciency of 0.75, for log-periodic dipole array (LPDA) antenna, is also validated from a reverberation chamber (RC) characterisation of a printed circuit-board (PCB) LPDA e ciency. A built-in pulse generator and the Square Kilometre Array (SKA) receiver RATTY form the main elements of the TD metrology. For validation purpose, a reference coaxial airline is built. The cable is characterised with computational codes (CST and FEKO) and is also modelled with Vance and Kley's analytical expressions. The results are compared with TD transfer impedance (Zt) measurement within the RC. The study shows that the cable fixture within an RC shapes the cable under-test (CUT) Zt. The airline itself is also introducing an oscillating component within Zt. The resonance is proportional to the CUT length and it is visible within the measurement data and the simulations. It is not, however, taken into account by the theoretical models. The consequence of an incorrect antenna efficiency on RC applications is also addressed using a PCB LPDA antenna efficiency investigation. The unknown LPDA is simulated with CST for the study. The result is compared to an RC measurement validating the IEC 61000-4-21 standard efficiency recommendation of 0.75 [1]. This methodology characterised the unknown antenna parameter from a reference dipole antenna efficiency we investigated with FEKO. Simulated Wheeler-cap techniques permitted the reference antenna validation. We found that an inaccurate LPDA efficiency has little effect at higher frequency if the IEC efficiency is adopted. However, a difference of more than 7 dB can arise at low frequency if the real efficiency differs by more than 0.3 with respect to the IEC value. The study highlights the importance of a correct antenna efficiency for accurate RC applications. The nested-enclosure technique is regarded as the conventional method of investigating small enclosures SE [2]. The technique is in general time-consuming and works for a frequency range higher than three times the enclosure under test (EUT) lowest cut-o value. Our TD metrology covers a frequency band up to 1.4 GHz which coincides with our enclosure under-moded region. The SE characterisation is not well-documented within this particular region. The dissertation contributes to this field using a non-stirred nested-enclosure configuration. In contrast to the conventional use of the nested-enclosure methodology [2], the source is placed here within the EUT and the enclosure is treated as a normal radiator. The SE definition according to the IEEE standard in [2] is followed and the enclosure total transferred-power is computed from the port's reflection coeficient. The approach does not require a stirrer for the EUT. Our measurement shows an SE agreement between the modfied and the appropriate nested-enclosure technique from 390 MHz up to 4 GHz. The investigation is faster, but in addition the TD spectrum gives a more detailed SE response than the FD approach. / AFRIKAANSE OPSOMMING: Elektromagnetiese skerming speel n belangrike rol in die beskerming van elektroniese komponente. Die toepassing daarvan is noodsaaklik vir die versagting van radiofrekwensie steurings in die Karoo Array Telescope (MeerKAT) projek wat tans ontwikkel word in die Karoo omgewing van die Noord-Kaap. In hierdie konteks is daar op n tydsgebied metode vir klein-omhulsel beskermingse ektiwiteit (BE) gefokus, deur gebruik te maak van n weerkatingsomgewing tegniek. Die belangstelling handel om metingstye te verkort en n uitgebreide BE reaksie wat die lae-modus toestand van klein omhulsels dek. Aanbeveelde International Electrotechnical Commission (IEC) standaard 61000-4-21 [2] e ektiwiteit van 0.75, vir log-periodiese dipool-skikking (LPDA) antennas, is ook bekragtig deur n weerkaatsingskamer karakterisering van n gedrukte-stroombaanbord (PCB) LPDS antenna e ektiwiteit. n Ingeboude impulsgenerator en die Square kilometre Array (SKA) ontvanger, RATTY, vorm deel van die hoof elemente van die tydsgebiedmetings. Vir bekragtigings doeleindes is n koaksiale lugtransmissielyn gebou. Hierdie kabel is gekarakteriseer deur numeriese sagteware (CST en FEKO) en is ook gemoduleer met behulp van Vance en Kley se analitiese uitdrukkings. Die resultate is vergelyk met tydsgebied-oordragsimpedansie (Zt) metings, wat in die weerkaatsingskamer gedoen is. Die studie wys dat kabel posisie binne in die weerkaatsingskamer die Zt van die kabel-onder-toets vervorm. Die lugstreep voeg ook n ossillerende component by tot die gemete Zt. Die resonansie is eweredig aan die lengte van die kabel en is duidelik sigbaar binne die meting- en simulasiedata. Dit is egter nie in-berekening gebring in die analitiese modelle nie. Die gevolge van n verkeerde antenna e ektiwiteit in die weerkaatsingskamer toepassing is ook aangespreek deur ondersoek na die e ektiwiteit van n PCB LPDA. Die onbekende LPDA is gesimuleer met CST vir hierdie studie. Die resultate is vergelyk met n weerkaatsingskamer meting, wat die IEC 61000-4-21 standaard e ektiwiteit van 0.75 [1] bekragtig. Die metode karakteriseer die onbekende antenna veranderlike deur n verwysings dipool antenna e ektiwiteit wat ge-ondersoek is in FEKO. Gesimuleerde Wheeler-cap tegnieke het die veri kasie van die verwysings antenna resultate toegelaat. Daar is gevind dat n onakkurate LPDA e ektiwiteit n klein e ek op die ho er frekwensies het, as die IEC e ektiwiteit aangeneem is. Daar kan egter n verskil van 7dB voorkom by laer frekwensies, as die werklike e ektiwiteit met meer as 0.3 van die IEC waarde verskil. Hierdie studie lig die belangrikheid van n korrekte antenna e ektiwiteit uit vir akkurate weerkaatsingskamer toepassings. Die geneste-omhulsel tegniek word beskou as die konvensionele metode vir die bestudering van beskermingse ektiwiteit vir klein omhulsels. Die tegniek is gewoontlik tyd-rowend en werk net vir frekwensies wat drie maal ho er is as die af-sny waarde van die omhulselonder- toets. Ons tydgebiedmeting dek net n frekwensieband tot 1.4GHz, wat ooreenstem met ons omhulsel lae-modus gebied. Die beskermingse ektiwiteit karakterisering, in hierdie spesi eke veld, is nie goed gedokumenteer nie. Hierdie verhandeling dra by tot hierdie veld deur gebruik te maak van n onversteurde geneste-omhulsel kon gurasie. In teenstelling met die konvensionele gebruik van die geneste-omhulsel metode, is die bron geplaas binne die omhulsel-onder-toets en word dit gebruik as n gewone uitstraler. Die de nisie van beskermingse ektiwiteit volgens die IEEE standaard in [2], is gevolg en die totale oordragskrag van die omhulsel is bereken deur gebruik te maak van n poort se re eksie ko e si ent. Die benadering benodig nie n steurder vir die omhulsel-onder-toets nie. Ons metings se beskermingse ektiwiteit het ooreengestem met die veranderde - en die geskikte geneste-omhulsel tegniek, van 390MHz tot 4GHz in die spektrum. Hierdie ondersoek is vinniger en lewer n meer gedetailleerde beskermingse ektiwiteit reaksie as die frekwensiegebied benadering.

The behaviour of zoo animals can come to anticipate temporally predictable feeding times. However, there is a lack of consensus over the effects of such routines on behaviour and welfare. Few studies have been published in this area, perhaps in part due to methodological challenges. The current programme of work therefore aimed to extend knowledge on the effect of predictable feeding routines, and to develop a suitable methodology to overcome challenges. Prior to predictable feeding, tigers showed patterns of increased ‘active’ behaviours such as locomotion and pacing, and decreased inactivity. Geckos also showed increased ‘active’ behaviours such as locomotion and ‘stationary but moving head’ prior to predictable, compared to unpredictable feeding times, with significant differences between conditions (RSS = 0.059 and 0.047, p < .05). However, anticipatory patterns were not demonstrated for meerkats, which highlighted that other environmental factors may affect an animal’s response to temporal predictability (such as obtaining other food during the day, or signalled predictability). Studying patterns of behavioural change over time requires long periods of observation which is often not possible for researchers. The current programme of work argues that a measure which can be reliably used by many, relatively untrained observers is necessary to study predictability. The measure of ‘busyness’, a subjective rating of animal behaviour, was tested for reliability and validity. Busyness ratings showed good inter-observer reliability (ICC > .72) and correlated with traditional measures of behaviour. Busyness ratings demonstrated clear patterns related to feeding time and gave a useful compound measure of behavioural change. The use of multiple observers was extended to a citizen science approach, where useful data on anticipation in fish were obtained from aquarium visitors using a touch screen. The current programme of work successfully investigated the effects of predictable feeding routines on patterns of animal behaviour, alongside the development of suitable methods. The qualitative techniques developed here offer potential to increase the data obtained in future research into predictability and many other topics.

>Magister Scientiae - MSc / Future radio surveys as the Square Kilometer Array (SKA) and its precursor, the "Meer" Karoo Array Telescope (MeerKAT), will map the Neutral Hydrogen (HI) in large areas of the sky using the intensity mapping (IM). HI IM is currently one of the most promising ways of accessing the Large-Scale Structure of the Universe. The distribution of matter in the Universe not only encodes its composition but also how it evolves and its initial conditions. An effect on the matter distribution that will be detected by the SKA on the post re-ionization Universe are the Baryonic Acoustic Oscillations (BAO). While it has been shown that in single dish mode the SKA can measure the BAO peak in the radial 21cm power spectrum at low redshifts, this possibility has not yet been studied in detail for the MeerKAT. In this thesis we construct a set of full sky simulations to test how well MeerKAT will be able to extract the BAO wiggles along the line of sight. These simulations are done for the frequencies corresponding to MeerKAT L-band. The maps combine the cosmological HI signal, systematic noise, cosmological foregrounds and the instrumental telescope beam. A model-independent estimator is used to extract the BAO wiggles by subtracting a smooth polynomial component from the 21cm radial power spectrum. We test with simulations if this estimator is biased and the signal to noise of the extraction. We conclude that we are able to remove contaminants and recover the cosmological HI signal while not risking the recovery of the BAO signal. We investigate the effects of varying the sky area and the observational hours on the signal to noise ratio for the BAO wiggles. We found that for a HI IM experiment using MeerKAT, the optimal sky area to detect the BAO along the line of sight is 50% of the sky. With a signal-to-noise ratio of 3.37. This can be achieved with 2000 hours of exposure time

Meerkats are known to strongly rely on chemical communication in social contexts. However, little is known about their use of the sense of smell in food detection and selection. The aim of the present study was therefore to assess whether meerkats are able to (1) detect hidden food using olfactory cues, (2) distinguish the odour of real food from a single food odour component, and (3) build an association between the odour of real food and a novel odour. I employed the buried food test, widely used with rodents to assess basic olfactory abilities, designed to take advantage of the propensity of meerkats to dig. I found that the meerkats were clearly able to find all four food types tested (mouse, chicken, mealworm, banana) using olfactory cues alone and that they successfully discriminated between the odour of real food and a food odour component. In both tasks, the animals dug in the food-bearing corner of the test arena as the first one significantly more often than in the other three corners, suggesting development of an efficient foraging strategy. No significant association-building between a food odour and a novel odour was found within the 60 trials performed per animal. I conclude that meerkats are able to use olfactory cues when foraging and that their sense of smell is well-adapted for recognizing specific odours of behavioural relevance. To the best of my knowledge, this is the first study to successfully employ the buried food test with a carnivore species.

>Magister Scientiae - MSc / The growth rate of large-scale structure is a key probe of gravity in the accelerating Universe. Standard models of Dark Energy within General Relativity predict essentially the same growth rate, whereas Modified Gravity theories without Dark Energy predict a different growth rate. Redshift-space distortions lead to anisotropy in the power spectrum, and extracting the monopole and quadrupole allows us to determine the growth rate and thus test theories of gravity. We investigate redshift-space distortions in the intensity maps of the 21cm emission line of neutral hydrogen (HI) in galaxies after the Epoch of Reionization: HI intensity mapping delivers very accurate redshifts. We first use the standard approach based on the Fourier power spectrum. Then we explored an alternative approach, based on the spherical-harmonic angular power spectrum. Fisher forecasting was used to make predictions of the accuracy with which MeerKAT will measure the growth rate parameter, via the proposed MeerKAT Large Area Synoptic Survey (MeerKLASS). Then we extend the forecasts to consider the planned HI intensity mapping survey in Phase 1 of the Square Kilometre Array. These forecasts enable us to predict at what level of accuracy General relativity and various alternative theories could be ruled out.

Acoustic analysis of animal vocalizations has been widely used to identify the presence of individual species, classify vocalizations, identify individuals, and determine gender. In this work automatic identification of speaker and gender of mice from ultrasonic vocalizations and speaker identification of meerkats from their Close calls is investigated. Feature extraction was implemented using Greenwood Function Cepstral Coefficients (GFCC), designed exclusively for extracting features from animal vocalizations. Mice ultrasonic vocalizations were analyzed using Gaussian Mixture Models (GMM) which yielded an accuracy of 78.3% for speaker identification and 93.2% for gender identification. Meerkat speaker identification with Close calls was implemented using Gaussian Mixture Models (GMM) and Hidden Markov Models (HMM), with an accuracy of 90.8% and 94.4% respectively. The results obtained shows these methods indicate the presence of gender and identity information in vocalizations and support the possibility of robust gender identification and individual identification using bioacoustic data sets.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Technical advances in electromagnetics, signal processing and processing power have led to a significant increase in sensitivity and accuracy in radio telescopes. With this increase in sensitivity, radio frequency interference (RFI) has become a much larger problem. The notable growth in wireless communication as well as self generated RFI has further escalated this problem. In order to utilise the full capabilities of modern radio telescopes, RFI mitigation is required on the captured signals. With the enormous data rates of modern radio telescopes, managing RFI has become increasingly difficult, and in order to utilise the full captured radio spectrum, more accurate RFI mitigation strategies will be necessary. The use of different RFI mitigation strategies is studied in the form of online and offline techniques. This includes Spectral Kurtosis, Spectral Flatness and the Var/SumThreshold method. The special case for RFI mitigation in timing pulsars will also be studied. These techniques are well known in the radio astronomy community; here, spectral kurtosis and spectral flatness will be implemented on the raw data as well as the post correlated data. System speed and accuracy will be the deciding factors when testing these methods as possible solutions to this problem. / AFRIKAANSE OPSOMMING: ‘n Toename in die sensitiwiteit van hedendagse radioteleskope kan toegedra word aan die tegniese bevordering in elktromagnetika en seinverwerking. Die toename in sensitiwiteit het egter tot die gevolg dat radiofrekwensiesteuring ‘n groter rol speel in hedendaagse radioteleskope. Die groei in die gebruik van radioverbindings asook die gevolge van self gei¨nduseerde radiofrekwensiesteuring dra ook verder by tot hierdie probleem. Radiofrekwensiesteuring matiging word toegepas op die opgevangde seine, om sodoende gebruik te maak van die volle kapasiteit van moderne radioteleskope. Die bestuur van radiofrekwensiesteuring word bemoeilik deur die groot hoeveelheid intydse data van die radioteleskope. Meer akurate radiofrekwensiesteuring matigingstegnieke word vereis om die bandwydte ten volle te hanteer. Daar word op ‘n aantal verskillende matingstegnieke gefokus. Hierdie tegenieke kan in twee kategorieë verdeel word, naamlik aanlyn- en aflyntegenieke. Onderafdelings van hierdie kategorieë sluit in: spektrale kurtose, spektrale matheid en “Var/SumThreshold”. Daar word ook na ‘n spesiale geval van radiofrekwensiesteuring matiging gekyk, in die opmeeting van tydsberekening-pulsars. Alhoewel hierdie tegnieke bekend is in die radioastronomie gemeenskap, word spektrale kurtose en spektrale matheid egter toegepas op die rou data sowel as postgekorreleerde data. Daar sal op stelsel spoed en akuratheid gefokus word, om vas te stel of hierdie metodes wel moontlike oplossings bied tot die probleem bespreek.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: This work in this study covers a powerful technique to derive propagation and scattering information in an expedient fashion. Expedient because time-domain (TD) data gathers a broad spectrum in a single transmitted pulse. TD has been criticised because of a lack of dynamic range, which has now been overcome by the direct sampling system, RATTY and RTA. This study focuses on the investigation of a TD metrology system, to assist with the characterisation of MeerKAT systems. The elementary components of the system include a fast-rising impulse generator that was coupled with an impulse radiating antenna (IRA). The system was calibrated and tested before practical measurements and preliminary testing in the Karoo were done. For TDmetrology a larger bandwidth accelerates measurements without the loss of accuracy. The pulse generator’s (PG’s) fundamental components are an avalanche transistor and a step recovery diode (SRD), to sharpen the leading edge of the pulse. Improving the rise-time of a pulse increases its bandwidth in the spectrum. The external circuitry around these components is pivotal and it determines the shape, amplitude and rise-time of the pulse. In the course of the investigation, the general circuitry around the PG was improved to obtain the best possible pulse for measurements inside a reverberation chamber (RC) and for measurements in the Karoo. In light of this, a second and third PG source were obtained. For measurements in the Karoo, a larger amplitude pulse was required to increase the spectral content and this is essential for propagation measurements over distance and the shielding effectiveness (SE) of structures. Stacking avalanche transistors allow larger amplitude pulses and it improves the dynamic range of the spectrum. A PG incorporating stacked avalanche transistors, was designed, built and measured to assist with RC and small-scale field measurements in the Karoo. The third PG was bought for the practical measurements in the Karoo. The PG produces kilovolt pulses with pico-second rise-times that extend the spectral range of the current PGs at our disposal. With these PGs, an antenna is required for the radiation of impulse-like transients. The IRA is a high-gain large-bandwidth antenna. The IRA consists of a parabolic reflector, conical-plate transmission lines that are terminated through resistors onto the dish, and a feeding balun. The IRA design was thoroughly discussed and a first model for metrology was designed, measured and optimised. The IRA was also simulated with computation software code, FEKO. Before deployment of theTDsystem, calibration and characterisation measurements are required. The measuring devices used within this study were sampling oscilloscopes and direct sampling systems. The limitations of each device were explored and are discussed. The final measurements that were conducted contribute to work related to the SKA. This incorporated antenna pattern calibration, propagation over distance and the SE of a berm built from Karoo soil. The system investigated the propagation attenuation over the Karoo soil and vegetation, with great promise. A broad spectrum was measured over a few kilometres and compared to free-space loss. The SE of the berm covered the same spectral bandwidth. In this measurement, scattering effects and knife-edge diffraction were observed. / AFRIKAANSE OPSOMMING: Die werk in hierdie studie dek ’n kragtige tegniek wat gebruik kan word om die voortplanting en die verstrooiingsinligting van elektromagnetiese golwe op ’n voordelige manier af te lei. Dit is voordelig, want tydgebieddata versamel ’n wye spektrum in ’n enkele oordraagbare puls. Tydgebied is in die verlede baie gekritiseer omdat dit ’n dinamiese reikwydte kortkom en dit is nou oorwin deur die direkte steekproefnemingstelsel, RATTY en RTA. Hierdie studie fokus op die ondersoek van ’n tydgebiedmetingssisteem en dit help met die karakterisering van MeerKAT sisteme. Die elementêre komponente van die sisteem bestaan uit ’n vinnig-stygende impulsgenerator wat gekoppel is aan ’n impulsuitstralende-antenna (IRA). Die sisteem is gekalibreer en getoets voordat praktiese metings en toetse in die Karoo uitgevoer kon word. Vir tydgebiedmetings versnel ’n groter bandwydte die metings sonder om die akkuraatheid daarvan te beïnvloed. Die pulsgenerator se fundamentele komponente is ’n stortvloedtransistor en ’n stap-herstel diode (SRD) wat die voorpunt van die puls verskerp. Die eskterne stroombaan rondom hierdie komponente is noodsaaklik en dit bepaal die vorm, amplitude en die stygtyd van die puls. Deur die loop van hierdie ondersoek is die algemene stroombaan rondom die puls verbeter, om die beste moontlike puls vir metings binne in die weerkaatsingskamer en vir metings in die Karoo, te verkry. Na aanleiding van dit is ’n tweede en derde pulsgenerator bron verkry. Vir die metings in die Karoo is ’n puls met ’n groter amplitude vereis om die spektrale inhoud te vermeerder. Dit is noodsaaklik vir elektromagnetiese golf voortplantingsmetings oor afstand asook die beskermings effektiwiteit (SE) van die strukture. Stapel-stortvloed transistors skep pulse met groter amplitudes en dit verbeter die dinamiese reikwydte van die spektrum. ’n Pulsgenerator wat gestapelde stortvloedtransistors insluit is ontwerp, gebou en gemeet om te help met metings in die weerkaatsingskamer en kleinskaal veldmetings in die Karoo. Die derde pulsgenerator is gekoop vir praktiese metings in die Karoo. Die pulsgenerator vervaardig kilovolt pulse met pikosekond stygtye, wat die reikwydte van die spektrum van ons huidige puls uitbrei. Hierdie pulsgenerators vereis ’n antenna vir die uistraling van impulsagtige seine. Die IRA is ’n hoë-wins, groot-bandwydte antenna. Die IRA bestaan uit ’n paraboliese weerkaatser, konieseplaat transmissielyne wat deur weerstande op die skottel getermineer word, asook ’n voedings "balun". Die IRA ontwerp is deeglik bespreek en ’n model is ontwerp, gemeet en verbeter. Die IRA is ook gesimuleer met behulp van ’n rekenaarsagtewareprogram, FEKO. Voordat die tydgebiedsisteem benut kan word, moet dit gekalibreer word en karakteriseringsmetings moet ook daarmee uitgevoer word. Die meetinstrumente wat in hierdie studie gebruik is, is steekproefneming-ossilloskope en direkte steekproefneming-sisteme. Die tekortkominge van elke instrument is ondersoek en bespreek. Die finale meting wat uitgevoer is, dra by tot die werk wat geassosieer word met die SKA. Dit behels antennapatroonkalibrasie, voortplanting van elektromagnetiese golwe oor afstand en die SE van ’n "berm"wat gebou is uit Karoo-grond. Hierdie sisteem is gebruik om die voortplantings-verswakking oor die Karoo-grond en plantegroei te ondersoek en dit lyk baie belowend. ’nWye spektrumis oor ’n paar kilometer gemeet en dit is met wrywinglose ruimte vergelyk. Die SE van die "berm"het dieselfde spektrale bandwydte gedek. In hierdie meting is verstrooiingseffekte en mespunt-diffraksie waargeneem.

This thesis presents a thorough and significant work on the properties of radio sources as derived from deep 610-MHz GMRT data and ancillary multi-wavelength data. The faint radio sources at 610-MHz are found out to distances such that the objects are seen as they were when the universe was less than half its current age. These data provide a first look at the faint radio sky at sensitivities that will soon be achieved by key programs on the South African MeerKAT radio telescope, and thus take a first step in the exploration of the radio universe that will be made by the Square Kilometre Array. I report deep 610-MHz GMRT observations of the EN1 field, a region of 1.86 deg2 . We achieve a nominal sensitivity of 7.1µ Jy beam−1 . From our 610 MHz mosaic image, we recover 4290 sources after accounting for multiple component sources down to a 5σ flux density limit of 35.5 µ Jy. From this data, I derive the 610 MHz source counts applying corrections for completeness, resolution bias and Eddington bias. The 610- MHz source counts show a flattening at flux densities below 1 mJy. The source counts are higher than previous observations at this frequency below this break. However, they are generally consistent with recent models of the low-frequency source population. Using ancillary multi-wavelength data in the field, I investigate the key issue of source population classification using the deepest data at an intermediate-low frequency (higher than LOFAR and lower than JVLA), where previous work has not been sensitive enough to reach the µJy population. By cross-matching against the multi-wavelength data, I identify 72% of the radio sample having reliable redshifts, of which 19% of the redshifts are based on spectroscopy. From the classification, I obtain 1685 sources as Star-Forming Galaxies (SFGs), 281 sources Radio-Quiet (RQ) and 339 sources Radio-Loud (RL) Active Galactic Nuclei (AGN) for the sub-sample with redshifts and at least one multi-wavelength AGN diagnostic. SFGs are mostly low-power radio sources, i.e L610 MHz < 1025 W Hz−1 while RQ AGN and RL AGN have radio powers L610 MHz > 1025 W Hz−1 . From cross-matching my sample with other radio surveys (GMRT at 325-MHz, FIRST at 1.4-GHz and JVLA at 5-GHz), I obtain the median spectral index from 325-MHz to 610-MHz to be −0.80 ± 0.29, 610-MHz to 1.4-GHz to be −0.83 ± 0.31 and 1.4-GHz to 5-GHz to be −1.12 ± 0.15. The main result is that the median spectral index appears to steepen at the highest frequency. With the above catalogue in hand, I use the non-parametric V/Vmax test and the radio luminosity function to investigate the cosmic evolution of different source populations. I study SFGs and derive their IR-radio correlation and luminosity function as a function of redshift. By integrating the evolving SFG luminosity functions I also derive the cosmic star formation rate density out to z = 1.5. I address the long standing question about the origin of radio emission in RQ AGN. I compare the star formation rate (SFR) derived from their far-infrared luminosity, as traced by Herschel, with the SFR computed from their radio emission. I find evidence that the main contribution to the radio emission of RQ AGN is the star formation activity in their host galaxies. At high luminosities, however, both SFGs and 1 RQ AGN display a radio excess when comparing radio and infrared star formation rates. The vast majority of our sample lie along the SFR − M? ”main sequence” at all redshifts when using infrared star formation rates. This result opens the possibility of using the radio band to estimate the SFR even in the hosts of bright AGN where the optical-to-mid-infrared emission can be dominated by the AGN. I investigate the evolution of radio AGN out to z ∼ 1.5 with continuous models of pure density and pure luminosity evolution with Φ? ∝ ( 1 + z)(2.25±0.38)−(0.63±0.35)z and L610 MHz ∝ ( 1 + z)(3.45±0.53)−(0.55±0.29)z respectively. I also constrain the evolution of RQ AGN and RL AGN separately with a continuous model of pure luminosity evolution. For the RQ and RL AGN, we find a fairly mild evolution with redshift best fitted by pure luminosity evolution with L610 MHz ∝ ( 1 + z)(2.81±0.43)−(0.57±0.30)z for RQ AGN and L610 MHz ∝ ( 1 + z)(3.58±0.54)−(0.56±0.29)z for RL AGN. The results reveal that the 610 MHz radio AGN population thus comprises two differently evolving populations whose radio emission is mostly SF-driven or AGN-driven respectively. Finally, I probe the infrared-radio correlation and radio spectral indices of the faint radio population using stacking. I stack infrared sources in the EN1 field using the MIPS 24 micron mid-infrared survey and radio surveys created at 325 MHz, 610 MHz and 1.4 GHz. The stacking experiment shows a variation in the absolute strength of the infrared-radio correlation between these three different frequencies and the MIPS 24 micron band. I find tentative evidence of a small deviation from the correlation at the faintest infrared flux densities. The stacked radio spectral index analyses reveal that the majority of the median stacked sources exhibit steep spectra, with a spectral index that steepens with frequency between α 325 610 and α 610 1400. This work is particularly useful to pave the way for upcoming radio surveys with SKA pathfinders and precursors.

Text in English and abstract in English, Afrikaans and isiZulu / This archaeozoological study was undertaken to distinguish between the two hare species of South Africa, Lepus capensis (Cape hare) and Lepus saxatilis (scrub hare), from fragmentary archaeological faunal remains. It was previously not possible to taxonomically differentiate between these species. The research focused on Lagomorpha remains previously identified in Later Stone Age assemblages from two rock shelters, Blydefontein and Meerkat, in the Karoo. Analyses of modern skeletal material housed in museum collections demonstrated that there are indeed morphological and morphometric differences between Lepus capensis and Lepus saxatilis. The Lagomorpha material from the two archaeological assemblages were then re-examined utilising the newly established protocols. The reanalyses proved that it is now possible to distinguish between the two hare species even when in fragmentary form. It is also possible to identify Pronolagus. The dietary and likely cultural roles of the Lagomorpha and other small mammals in archaeological contexts are also explored. / Hierdie argeosoölogiese studie is onderneem om te onderskei tussen die twee haasspesies in Suid-Afrika, Lepus capensis (vlakhaas) en Lepus saxatilis (kolhaas), aan die hand van gefragmenteerde argeologiese fauna-oorblyfsels. Dit was nie voorheen moontlik om hierdie spesies taksonomies van mekaar te onderskei nie. Die navorsing fokus op Lagomorpha-oorblyfsels wat voorheen geïdentifiseer is in rotsskuiling-versamelings wat uit die Laat Steentydperk dateer. Die genoemde rotsskuilings is gevind by Blydefontein en Meerkat in die Karoo. Ontledings van moderne skeletmateriaal in museumversamelings het getoon dat daar wel morfologiese en morfometriese verskille tussen Lepus capensis en Lepus saxatilis is. Lagomorpha-materiaal afkomstig van die twee argeologiese versamelings is toe herondersoek aan die hand van nuut gevestigde protokolle. Die herontledings het bewys dat dit nou moontlik is om te onderskei tussen die twee haasspesies, selfs indien hulle gefragmenteerd is. Dit is ook moontlik om Pronolagus te identifiseer. Die rolle wat die Lagomorpha en ander klein soogdiere in argeologiese kontekste in dieet en kultuur vervul het, is ook ondersoek. / Ucwaningo maqondana nezitho zomzimba ezisalayo uma isilwane sesifile lwenziwelwa ukuba kukwazeke ukuhlukanisa phakathi kwalezi zinhlobo ezimbili zonogwaja eNingizimu Afrika, okuyiLepus capensis kanye neLepus saxatilis ngokubheka izingcucu zezinsalela zazo. Kwakungelula kudala ukuhlukanisa lezi zinhlobo zesilwane ngokwamaqoqo okwakheka noma okwenza kwazo. Ucwaningo lugxile kwizinsalela zohlobo lweLagomorpha olwaluvame ukubonakala ngenkathi yakudala okwakusetshenziswa kuyo amatshe ukwakha izinto (iStone Age) emiphemeni emibili eyayakhiwe ngamadwala eyayihlangene eyayaziwa ngokuthi yiBlydefontein neMeerkat esigodini esisagwadule esiseNingizimu Afrika, iKaroo. Ukuhlaziywa kwezingebhezi zemizimba yezinto ezigcinwe kwizigcinamagugu lwaveza ukuthi impela ukhona umehluko ekwakhekeni kanye nasezilinganisweni zogebhezi lwekhanda ngokomumo kumbe ugebhezi lwesiqu somzimba phakathi konogwaja abawuhlobo lweLepus capensis neLepus sexatilis. Uhlobo lweLagomorpha lwasesakhiweni semipheme ehlangene lwabe seluhlolwa kabusha kusetshenziswa izinhlobo ezintsha eziseqophelweni. Ukuhlaziywa kabusha kwaveza ubufakazi bokuthi sekuyinto engenzeka kalula ukuhlukanisa phakathi kwalezi zinhlobo ezimbili zonogwaja ngisho ngabe sezitholakala sezingcezungcezu. Kuyinto engenzeka kalula futhi ukubona uhlobo lwePronolagus. Indlela yokudla kanye nemisebenzi ehambisana nosikompilo kohlobo lweLagomorpha kanye nezinye izilwane ezincelisayo nakho kuyabhekwa. / Anthropology and Archaeology / M.A. (Archaeology)