An analysis of export support measures with special reference to South Africa, and the impact of the general export incentive scheme.

Thesis (M.Com.)-University of Natal, 1996.South Africa, in common with many other developing countries, embarked on an import substitution policy to promote development and industrialisation. Although initially successful, it was recognised in the late 1960s that the scope for further import substitution was limited and that alternative development strategies should be embarked upon. Unfortunately, the years of import substitution resulted in high levels of protection and consequently an anti-export bias. In 1972, under the leadership of Dr Reynders, a commission found that South Africa should embark upon a policy of export promotion. In 1980 a new form of export incentive was introduced, viz. Category A and B. Category A incentives were aimed at neutralising the effects of import substitution and compensated exporters fifty per cent of the duty payable on inputs, regardless of whether the inputs were imported or not. Category B incentives compensated exporters for the consequences of cost increasing on non-intermediate inputs because of the import substitution policy and was calculated on the value added. Exporters also enjoyed various grants and tax breaks to enable them to undertake export marketing. The schemes were unsuccessful and were replace by a General Export Incentive Scheme (GElS) in 1990. The main aim of the GElS was to encourage the export of manufactured products. With the means of an econometric model, the success of GElS is evaluated on a sectoral basis. GElS brought with it rent seeking, corruption, lobbying, and threats of countervailing duties. In addition to the enormous costs, exceeding R6 billion, there were other bureaucratic costs. In general, the GElS was not successful. The sectors that did benefit from receiving GElS benefits were the tobacco industry, footwear, furniture, metal products, and electrical machinery. In most cases, exporters would have exported with or without GElS. GElS was simply a windfall. Policy-makers failed to recognise the dynamics of exporting. GElS contributed neither to additional exports, export capacity nor to a sustained competitive advantage. import substitution policy to promote development and industrialisation. Although initially successful, it was recognised in the late 1960s that the scope for further import substitution was limited and that alternative development strategies should be embarked upon. Unfortunately, the years of import substitution resulted in high levels of protection and consequently an anti-export bias. In 1972, under the leadership of Dr Reynders, a commission found that South Africa should embark upon a policy of export promotion. In 1980 a new form of export incentive was introduced, viz. Category A and B. Category A incentives were aim.ed at neutralising the effects of import substitution and compensated exporters fifty per cent of the duty payable on inputs, regardless of whether the inputs were imported or not. Category B incentives compensated exporters for the consequences of cost increasing on non-intermediate inputs because of the import substitution policy and was calculated on the value added. Exporters also enjoyed various grants and tax breaks to enable them to undertake export marketing. The schemes were unsuccessful and were replace by a General Export Incentive Scheme (GElS) in 1990. The main aim of the GElS was to encourage the export of manufactured products. With the means of an econometric model, the success of GElS is evaluated on a sectoral basis. GElS brought with it rent seeking, corruption, lobbying, and threats of countervailing duties. In addition to the enormous costs, exceeding R6 billion, there were other bureaucratic costs. In general, the GElS was not successful. The sectors that did benefit from receiving GElS benefits were the tobacco industry, footwear, furniture, metal products, and electrical machinery. In most cases, exporters would have exported with or without GElS. GElS was simply a windfall. Policy-makers failed to recognise the dynamics of exporting. GElS contributed neither to additional exports, export capacity nor to a sustained competitive advantage

Measurement of crosstalk in stereoscopic display systems used for vision research

Studying binocular vision requires precise control over the stimuli presented to the left and right eyes. A popular technique is to segregate signals either temporally (frame interleaving), spectrally (using coloured filters) or through light polarization. None of these segregation methods achieves perfect isolation, and so a degree of ‘crosstalk’ is usually apparent in which signals intended for one eye are faintly visible to the other eye. Previous studies have reported crosstalk values mostly for consumer-grade systems. Here we measure crosstalk for eight systems, many of which are intended for use in vision research. We provide benchmark crosstalk values, report a negative crosstalk effect in some LCD-based systems, and give guidelines for dealing with crosstalk in different experimental paradigms

The determinants of South African exports : critical policy implications

This study takes an eclectic approach drawing on historic, theoretical and empirical sources to identify the main factors influencing the pattern and direction of South Africa’s trade. Rather than focusing on and proving or disproving individual theories, it looks at the broadly at various determinants of trade rather. Each of the theories that have been accepted as part of the canon of international trade theory explains part of the picture. This study therefore focuses on informing policy and therefore identifies and critically evaluates the determinants of South African exports and the role these determinants should have in policy development. Trade volume is usually seen as determined by the level of income level and relative prices. These are in turn determined by the dynamics of each GDP component (investment, consumption, public expenditure, exports); the price competitiveness of domestic production (influenced by exchange and relative inflation rates); non-price competitiveness of domestic production (product quality, technological innovativeness, design, promotion); the country’s attitude toward foreign goods; historical links with certain origin countries; and economic integration. This study attempts to isolate the determinants of export prices and volumes for the different manufacturing sectors. It will give policy-makers a clearer understanding of exporters and the factors that contribute to export growth, and will in turn inform policies, programmes and other export schemes. This information will allow the evaluation of the impact of their decisions and policies on each of the sectors’ export performance. Different sectors and industries face a myriad of different, and often unique conditions: elasticity, technology, market supply positions etc., and will therefore react differently to different policies. While government makes policy decisions that impact on the whole economy, it simultaneously has programmes that assist firms (particularly the Small Enterprise Development Agency (SEDA) and Trade and Investment South Africa (TISA)). This micro-level support and macro-policy must therefore operate together and complement each other. After setting the global and domestic scene, highlighting relevant events and trends that effect trade, this study critically evaluates international and South Africa applications of classical and new trade theories. From these processes, determinants are identified. Econometric models are then applied to test these determinants empirically. These techniques are applied to South Africa’s various sectors and industries thus giving macro- and meso-determinants. Qualitative techniques are then used to determine specific drivers at a firm level. From this a model is proposed for specific interventions to assist new exporters enter global markets, and to retain and grow existing exporters. Based on sound economic theory and the empirical findings from these research approaches, policy recommendations are made. In an increasingly competitive and uncompromising world, the role of sound policy is fundamental to economic success. This thesis argues that policy must be comprehensive and made with an understanding of the critical interactions in place.Thesis (DCom (Economics))--University of Pretoria, 2006.Economicsunrestricte

Initial stage selective laser flash sintering of aluminum nitride

Flash sintering is a form of sintering where electric fields are combined with heating to reduce the time and temperature required to densify ceramic powder compacts. A previous study with yttria-stabilized zirconia has shown that selective laser flash sintering (SLFS) is possible in which a scanning laser is used to selectively flash sinter a local region of the sample. SLFS presents the opportunity to avoid many of the drawbacks of current indirect additive manufacturing methods that utilize a binder. In this work, we demonstrate that aluminum nitride can also undergo SLFS using a combination of measurements of electric current flowing through the sample and observations of necks formed between powder particles. The scan conditions required to initiate SLFS are characterized over a range of laser powers and laser scan speeds. It is shown that the initiation of SLFS in AlN is governed by both the local heat input and heat dissipation. A numerical model that accounts for heat input using the product of the power intensity and laser interaction time and heat dissipation from conduction, convection, and radiation is developed. This model suggests that, consistent with furnace-based flash sintering, a minimum temperature along the conductive path determines the onset of sintering. Under an applied field of 3000 V/cm, temperatures of 450 – 475 K are predicted to initiate SLFS in AlN in 1.25 – 0.25 s. A second model is developed to determine the characteristics of sintering at the micro-scale for various combinations of heating and electrical fields, and particle geometries. This model suggests that the time to the onset of flash sintering is strongly dependent on the applied laser heating for the range of electric fields typically applied in SLFS. It also suggests that the time to the onset of SLFS is less dependent on electric field, but that after flash initiates the field strongly effect the temperature in the scanned region of the sample.Mechanical Engineerin

Morphometric analyses of the visual pathways in macular degeneration

Introduction. Macular degeneration (MD) causes central visual field loss. When field defects occur in both eyes and overlap, parts of the visual pathways are no longer stimulated. Previous reports have shown that this affects the grey matter of the primary visual cortex, but possible effects on the preceding visual pathway structures have not been fully established. Method. In this multicentre study, we used high-resolution anatomical magnetic resonance imaging and voxel-based morphometry to investigate the visual pathway structures up to the primary visual cortex of patients with age-related macular degeneration (AMD) and juvenile macular degeneration (JMD). Results. Compared to age-matched healthy controls, in patients with JMD we found volumetric reductions in the optic nerves, the chiasm, the lateral geniculate bodies, the optic radiations and the visual cortex. In patients with AMD we found volumetric reductions in the lateral geniculate bodies, the optic radiations and the visual cortex. An unexpected finding was that AMD, but not JMD, was associated with a reduction in frontal white matter volume. Conclusion. MD is associated with degeneration of structures along the visual pathways. A reduction in frontal white matter volume only present in the AMD patients may constitute a neural correlate of previously reported association between AMD and mild cognitive impairment. Keywords: macular degeneration - visual pathway - visual field - voxel-based morphometryComment: appears in Cortex (2013

Power contours : optimising sample size and precision in experimental psychology and human neuroscience

When designing experimental studies with human participants, experimenters must decide how many trials each participant will complete, as well as how many participants to test. Most discussion of statistical power (the ability of a study design to detect an effect) has focussed on sample size, and assumed sufficient trials. Here we explore the influence of both factors on statistical power, represented as a two-dimensional plot on which iso-power contours can be visualised. We demonstrate the conditions under which the number of tri- als is particularly important, i.e. when the within-participant variance is large relative to the between-participants variance. We then derive power contour plots using existing data sets for eight experimental paradigms and methodologies (including reaction times, sensory thresholds, fMRI, MEG, and EEG), and provide example code to calculate estimates of the within- and between-participant variance for each method. In all cases, the within-participant variance was larger than the between-participants variance, meaning that the number of trials has a meaningful influence on statistical power in commonly used paradigms. An online tool is pro- vided (https://shiny.york.ac.uk/powercontours/) for generating power contours, from which the optimal combination of trials and participants can be calculated when designing future studies

Magnified neural envelope coding predicts deficits in speech perception in noise

Verbal communication in noisy backgrounds is challenging. Understanding speech in background noise that fluctuates in intensity over time is particularly difficult for hearing-impaired listeners with a sensorineural hearing loss (SNHL). The reduction in fast-acting cochlear compression associated with SNHL exaggerates the perceived fluctuations in intensity in amplitude-modulated sounds. SNHL-induced changes in the coding of amplitude-modulated sounds may have a detrimental effect on the ability of SNHL listeners to understand speech in the presence of modulated background noise. To date, direct evidence for a link between magnified envelope coding and deficits in speech identification in modulated noise has been absent. Here, magnetoencephalography was used to quantify the effects of SNHL on phase locking to the temporal envelope of modulated noise (envelope coding) in human auditory cortex. Our results show that SNHL enhances the amplitude of envelope coding in posteromedial auditory cortex, whereas it enhances the fidelity of envelope coding in posteromedial and posterolateral auditory cortex. This dissociation was more evident in the right hemisphere, demonstrating functional lateralization in enhanced envelope coding in SNHL listeners. However, enhanced envelope coding was not perceptually beneficial. Our results also show that both hearing thresholds and, to a lesser extent, magnified cortical envelope coding in left posteromedial auditory cortex predict speech identification in modulated background noise. We propose a framework in which magnified envelope coding in posteromedial auditory cortex disrupts the segregation of speech from background noise, leading to deficits in speech perception in modulated background noise

Increasing spatial frequency of S-cone defined gratings reduces their visibility and brain response more than for gratings defined by L-M cone contrast

Chromatic sensitivity reduces as spatial frequency increases. Here, we explore the behavioural and neuronal responses to chromatic stimuli at two spatial frequencies for which the difference in sensitivity will be greater for S-cone than L-M stimuli. Luminance artefacts were removed using the Random Luminance Modulation (RLM) technique. As expected, doubling the spatial frequency increased the detection threshold more for S-cone than for isoluminant L-M gratings. We then used fMRI to measure the cortical BOLD responses to the same two chromatic stimuli (S and L-M) at the same two spatial frequencies. Responses were measured in six visual areas (V1, V2, V3, V3a, hV4, TO1/2). We found a significant interaction between spatial frequency in V1, V2 and V4 suggesting that the behaviourally observed increase in contrast threshold for high spatial frequency S-cone stimuli is reflected in these retinotopic areas. Our measurements show that neural responses consistent with psychophysical behaviour in a colour detection task can be observed as early as primary visual cortex

Triple visual hemifield maps in a case of optic chiasm hypoplasia

In humans, each hemisphere comprises an overlay of two visuotopic maps of the contralateral visual field, one from each eye. Is the capacity of the visual cortex limited to these two maps or are plastic mechanisms available to host more maps? We determined the cortical organization of the visual field maps in a rare individual with chiasma hypoplasia, where visual cortex plasticity is challenged to accommodate three hemifield maps. Using high-resolution fMRI at 7T and diffusion-weighted MRI at 3T, we found three hemiretinal inputs, instead of the normal two, to converge onto the left hemisphere. fMRI-based population receptive field mapping of the left V1-V3 at 3T revealed three superimposed hemifield representations in the left visual cortex, i.e. two representations of opposing visual hemifields from the left eye and one right hemifield representation from the right eye. We conclude that developmental plasticity including the re-wiring of local intra- and cortico-cortical connections is pivotal to support the coexistence and functioning of three hemifield maps within one hemisphere