Die sin en sintaksis in die Bantoetale

Waar ek my ten doel stel om in hierdie rede die soek- lig op die sin en sintaksis te laat val, wil ek dit voorop stel dat die studie uit die aard van die saak alleen daarop gerig kan wees om die riglyne vir ’n sintaktiese beskrywing vir die Bantoetale te trek, en nie om ’n volledige beskrywing van die tale se sinsbou te gee nie. Die Departement Bantoetale het ’n tweeledige taak, nl. ’n praktiese en ’n akademiese; om die rede is die onderhawige probleem ’n dringende

The Effect of Different Magnetospheric Structures on Predictions of Gamma-ray Pulsar Light Curves

The second pulsar catalogue of the Fermi Large Area Telescope (LAT) will contain in excess of 100 gamma-ray pulsars. The light curves (LCs) of these pulsars exhibit a variety of shapes, and also different relative phase lags with respect to their radio pulses, hinting at distinct underlying emission properties (e.g., inclination and observer angles) for the individual pulsars. Detailed geometric modelling of the radio and gamma-ray LCs may provide constraints on the B-field structure and emission geometry. We used different B-field solutions, including the static vacuum dipole and the retarded vacuum dipole, in conjunction with an existing geometric modelling code, and constructed radiation sky maps and LCs for several different pulsar parameters. Standard emission geometries were assumed, namely the two-pole caustic (TPC) and outer gap (OG) models. The sky maps and LCs of the various B-field and radiation model combinations were compared to study their effect on the resulting LCs. As an application, we compared our model LCs with Fermi LAT data for the Vela pulsar, and inferred the most probable configuration in this case, thereby constraining Vela's high-altitude magnetic structure and system geometry.Comment: 6 pages, 4 figures, conference article, appears in Proceedings of SAIP2012, the 57th Annual Conference of the South African Institute of Physics, edited by Johan Janse van Rensburg, ISBN: 978-1-77592-070-

Perception and Inference

This project explores the connections between normativity, perception, and conceptual content, and develops a view on which perception has inferentially-articulated conceptual content that is grounded in the way perceptual experiences alter the normative statuses of perceivers. In chapter two I address a criticism developed by Tyler Burge, who argues that views that require perceivers to have sophisticated capacities, such as conceptual or inferential capacities, in order to have representationally contentful perceptual states conflict with our best understanding of vision science. I argue that even if, as Burge claims, non-rational creatures have representational perceptual states that do not depend in any way on such capacities, nonetheless the perceptual states of rational creatures must be integrated with their conceptually contentful mental states and must be capable of serving as reasons for belief, given the role these states must play in the explanation of the representational perspectives of rational creatures. In chapter three I develop and defend a specific version of conceptualism on which the conceptual content of perception is grounded in its normative significance. Specifically, I claim, by analogy with inferentialist metasemantic accounts of meaning, that perception has conceptual content by virtue of the way that it warrants perceivers in applying concepts and entitles them to claims. I also argue, against Robert Brandom, that giving perception this kind of role is required in order to give an adequate semantics for natural languages. I then apply this view to provide an explanation of the object-directedness of perception. In chapter four I pair this inferentialist account of perceptual content with a relationalist approach to the metaphysics and phenomenology of perception. Most relationalists argue that their view is incompatible with the claim that perception has content, but I argue that the way the inferentialist account grounds the content of perception in normative features of experience makes it more compatible with relationalist approaches than many other similar views. I then respond to a specific problem raised for the content view by Charles Travis, and provide an explanation of the relationship between the phenomenology and content of perception on the basis of my response to this problem

Development of lubricating oils suitable for use with liquid oxidizers Final summary report, 4 Mar. 1968 - 4 Mar. 1969

Lubricating properties and impact stability of polyfluoroalcohol derivatives at low temperatur

Spatial patterning of prey at reproduction to reduce predation risk: what drives dispersion from groups?

Group living is a widespread behavior thought to be an evolutionary adaptation for reducing predation risk. Many group-living species, however, spend a portion of their life cycle as dispersed individuals, suggesting that the costs and benefits of these opposing behaviors vary temporally. Here, we evaluated mechanistic hypotheses for explaining individual dispersion as a tactic for reducing predation risk at reproduction (i.e., birthing) in an otherwise group-living animal. Using simulation analyses parameterized by empirical data, we assessed whether dispersion increases reproductive success by (i) increasing predator search time, (ii) reducing predator encounter rates because individuals are inconspicuous relative to groups, or (iii) eliminating the risk of multiple kills per encounter. Simulations indicate that dispersion becomes favorable only when detectability increases with group size and there is risk of multiple kills per encounter. This latter effect, however, is likely the primary mechanism driving females to disperse at reproduction because group detectability effects are presumably constant year-round. We suggest that the risk of multiple kills imposed by highly vulnerable offspring may be an important factor influencing dispersive behavior in many species, and conservation strategies for such species will require protecting sufficient space to allow dispersion to effectively reduce predation risk

On the occurrence and motion of decametre-scale irregularities in the sub-auroral, auroral, and polar cap ionosphere

International audienceThe statistical occurrence of decametre-scale ionospheric irregularities, average line-of-sight (LOS) Doppler velocity, and Doppler spectral width in the sub-auroral, auroral, and polar cap ionosphere ( - 57°L to - 88°L) has been investigated using echoes recorded with the Tasman International Geospace Environment Radar (TIGER), a SuperDARN radar located on Bruny Island, Tasmania (147.2° E, 43.4° S geographic; - 54.6 °L). Results are shown for routine soundings made on the magnetic meridian beam 4 and the near zonal beam 15 during the sunspot maximum interval December 1999 to November 2000. Most echoes were observed in the nightside ionosphere, typically via 1.5-hop propagation near dusk and then via 0.5-hop propagation during pre-midnight to dawn. Peak occurrence rates on beam 4 were often > 60% near magnetic midnight and ~ - 70 °L. They increased and shifted equatorward and toward pre-midnight with increasing Kp (i.e. Bz southward). The occurrence rates remained very high for Kp > 4, de-spite enhanced D-region absorption due to particle precipitation. Average occurrence rates on beam 4 exhibited a relatively weak seasonal variation, consistent with known longitudinal variations in auroral zone magnetic activity (Basu, 1975). The average echo power was greatest between 23 and 07 MLT. Two populations of echoes were identified on both beams, those with low spectral width and a mode value of ~ 9 ms-1 (bin size of 2 ms-1) concentrated in the auroral and sub-auroral ionosphere (population A), and those with high spectral width and a mode value of ~ 70 ms-1 concentrated in the polar cap ionosphere (population B). The occurrence of population A echoes maximised post-midnight because of TIGER's lower latitude, but the subset of the population A echoes observed near dusk had characteristics reminiscent of "dusk scatter" (Ruohoniemi et al., 1988). There was a dusk "bite out" of large spectral widths between ~ 15 and 21 MLT and poleward of - 67 °L, and a pre-dawn enhancement of large spectral widths between ~ 03 and 07 MLT, centred on ~ - 61 °L. The average LOS Doppler velocities revealed that frequent westward jets of plasma flow occurred equatorward of, but overlapping, the diffuse auroral oval in the pre-midnight sector

Alamethicin channels – modelling via restrained molecular dynamics simulations

AbstractAlamethicin channels have been modelled as approximately parallel bundles of transbilayer helices containing between N=4 and 8 helices per bundle. Initial models were generated by in vacuo restrained molecular dynamics (MD) simulations, and were refined by 60 ps MD simulations with water molecules present within and at the mouths of the central pore. The helix bundles were stabilized by networks of H-bonds between intra-pore water molecules and Gln-7 side-chains. Channel conductances were predicted on the basis of pore radius profiles, and suggested that the N=4 bundle formed an occluded pore, whereas pores with N≥5 helices per bundle were open. Continuum electrostatics calculations suggested that the N=6 pore is cation-selective, whereas pores with N≥7 helices per bundle were predicted to be somewhat less ion-selective