Thesis

Thesis (MA (Philosophy))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: This thesis consists of two essays, each focussing on a current topic in aesthetics in the tradition of analytic philosophy. First paper (On depiction) Given broad consensus that resemblance theories do not do well at explaining depiction, two alternative approaches have dominated the literature in recent decades: (1) Perceptual accounts try to ground depiction in the phenomenology of our pictorial experiences; (2) Structural accounts understand pictures as symbols in pictorial symbol systems. I follow Dominic Lopes in granting that the two approaches, often interpreted as each other’s rivals, both have merit and are successful in answering divergent questions about depiction. After taking stock of the most influential theories from both approaches, I turn to John Kulvicki’s recent work. He has made surprising progress as a proponent of the structural approach. His attempt to define depiction in structural terms is groundbreaking and, for the most part, successful. The paper measures some of his suggestions on picture structure and perception against the well-established “twofoldness”-thesis of the perceptual theorist on depiction, Richard Wollheim. Wollheim’s theory is defended and suggestions made to adapt Kulvicki’s theory accordingly. Second paper (On expression) Since Frank Sibley’s early papers in the mid-twentieth century, analytic aesthetics has broadened its field of inquiry to extend past the traditional focus on judgements of beauty or aesthetic merit, to peripheral terms, concepts, properties and judgements (e.g. of grace, elegance, garishness, daintiness, dumpiness, etc.). Nick Zangwill gives a traditionalist report of what binds the new, broad and heterogeneous category of the aesthetic together. He argues that purely evaluative aesthetic judgements of beauty or ugliness (i.e. “verdicts”) are fundamental. All other aesthetic judgements derive their evaluative aesthetic nature from them. In this essay it is argued that Zangwill’s defence of beauty’s supremacy in the category of the aesthetic, does not do justice to ostensible instances of non-evaluative judgements that ascribe expressive properties to artworks. Nelson Goodman’s cognitivist theory of expression in art is used as a foil for Zangwill’s claims.AFRIKAANSE OPSOMMING: Hierdie tesis bestaan uit twee essays, elk oor ’n aktuele onderwerp in estetika in die tradisie van die analitiese filosofie. Eerste essay (Oor uitbeelding, oftewel “piktoriale representasie”) Gegewe ’n algemene konsensus dat ooreenkoms-teorieë nie slaag daarin om uitbeelding (“depiction”) te verklaar nie, is daar twee alternatiewe benaderings wat die onlangse literatuur oor die onderwerp oorheers: (1) die perseptuele benadering probeer uitbeelding begrond in die fenomenologie van ons piktoriale ervaringe; (2) die strukturele benadering verstaan beelde as simbole in piktoriale simboolsisteme. In navolging van Dominic Lopes neem ek aan dat dié twee benaderings, wat normaalweg as mekaar se opponente beskou word, altwee meriete dra en onderskeidelik sukses behaal in die beantwoording van heel uiteenlopende vrae oor die aard van uitbeelding. Na ’n bestekopname van die mees invloedryke teorieë onder beide benaderings, word John Kulvicki se onlangse werk oorweeg. Hy maak verrassende vooruitgang as ondersteuner van die strukturele benadering. Sy poging om uitbeelding in strukturele terme te definiëer is revolusionêr en bied stof vir nadenke. In hierdie essay word sommige van sy voorstelle oor beeld-struktuur en -waarneming gemeet aan die gevestigde “twofoldness”-tesis van Richard Wollheim. Wollheim se perseptuele teorie word verdedig en ’n voorstelle word gemaak om Kulvicki se teorie daarvolgens aan te pas. Tweede essay (Oor uitdrukking) Sedert Frank Sibley se vroeë essays in die middel van die twintigste eeu het die analitiese estetika sy visier verbreed om verby die tradisionele fokus op oordele van skoonheid en estetiese waarde te kyk, na perifere terme, begrippe, eienskappe en oordele (van bv. grasie, delikaatheid, balans, strakheid, elegansie, ens., ens.). Nick Zangwill gee ’n tradisionalistiese verslag van wat die nuwe, breë en heterogene kategorie van die estetiese saambind. Hy argumenteer dat suiwer evaluerende oordele van skoonheid fundamenteel bly. Alle ander estetiese oordele se estetiese aard word daarvan afgelei. In hierdie essay argumenteer ek dat Zangwill se verdediging van skoonheid (of estetiese waarde) as fundamenteel tot die kategorie van die estetiese, nie laat reg geskied aan aantoonbare gevalle van nie-evaluerende oordele, naamlik dié wat ekspressiewe eienskappe aan kunswerke toeskryf, nie. Nelson Goodman se kognitiewe teorie van van uitdrukking in kuns word gebruik as teenhanger en wegspringplek vir kritiek op Zangwill se aansprake

A novel Malonamide Periodic Mesoporous Organosilica (PMO) for controlled Ibuprofen release

Controlled drug release gained a sharply increasing interest over recent years. Multiple materials have been screened as possible drug carriers, ranging from biodegradable polymers to hydroxyapatite[1]. Periodic Mesoporous Organosilicas are valuable alternatives as they possess a high chemical and thermal stability combined with a biocompatible nature[2]. Furthermore, their large internal surface area permits a high drug loading. Careful selection of the organic ‘bridged’ functionality allows a controlled release with respect to external stimuli, such as pH or temperature, of the drugs which are adsorbed via weak and reversible interactions, e.g. H-bonding, ionic and hydrophobic-phobic interaction[3]. In this contribution a novel malonamide (MA-PMO) and a methyl-malonamide PMO (mMA-PMO) bearing a high amount of functionalities, capable of multiple intramolecular interactions, are developed and thoroughly characterized[4]. Subsequently, these hybrid materials are evaluated in the controlled drug release of Ibuprofen

Potts models in the continuum. Uniqueness and exponential decay in the restricted ensembles

In this paper we study a continuum version of the Potts model. Particles are points in R^d, with a spin which may take S possible values, S being at least 3. Particles with different spins repel each other via a Kac pair potential. In mean field, for any inverse temperature there is a value of the chemical potential at which S+1 distinct phases coexist. For each mean field pure phase, we introduce a restricted ensemble which is defined so that the empirical particles densities are close to the mean field values. Then, in the spirit of the Dobrushin Shlosman theory, we get uniqueness and exponential decay of correlations when the range of the interaction is large enough. In a second paper, we will use such a result to implement the Pirogov-Sinai scheme proving coexistence of S+1 extremal DLR measures.Comment: 72 pages, 1 figur

Convex treemaps with bounded aspect ratio

Treemaps are a popular technique to visualize hierarchical data. The input is a weighted tree T where the weight of each node is the sum of the weights of its children. A treemap for T is a hierarchical partition of a rectangle into simply connected regions, usually rectangles. Each region represents a node of T and the area of each region is proportional to the weight of the corresponding node. An important quality criterium for treemaps is the aspect ratio of its regions. Unfortunately, one cannot bound the aspect ratio if the regions are restricted to be rectangles. Hence Onak and Sidiropoulos introduced polygonal partitions, which use convex polygons. We are the first to obtain convex partitions with optimal aspect ratio O(depth(T )). We also consider the important special case that depth(T ) = 1, that is, single-level treemaps. We show how to construct convex single-level treemaps that use only four simple shapes for the regions and have aspect ratio at most 34/7

Validation of a spectral light scattering method to differentiate large from small particles in intraocular lenses.

A psychophysical approach has been designed to measure straylight from intraocular lenses (IOLs) in vitro. This approach uses a clinical straylight meter (C-Quant) and an observer's eye as optical detector. Based on this, we introduced a method for study of straylight-wavelength dependency for IOLs. This dependency can be used to distinguish between 2 types of scattering particles (small and large) as defined by Mie theory. Validation was performed using a turbidity standard and scattering filters. Several IOLs were analyzed to identify potential scattering sources. Large particles were found to predominate in scattering from the studied lenses. This was confirmed by straylight-angular dependency found in these IOLs

Reconstruction of sea surface temperatures from the oxygen isotope composition of fossil planktic foraminifera.

Knowledge of the historic surface temperature of sea water is of importance for the calibration of climate models. The oxygen isotope composition of the shells of several species of planktic foraminifera can be used as a measure for this sea surface temperature. In this paper we investigate how mathematical models can contribute to the process of extracting information about the temperature at which the foraminifera lived from measurement of the oxygen isotope composition of their shells. A simple model is proposed which captures both the average and the variability of the temperature. Preliminary findings suggest that this model forms a solid basis for future research

Cognitive control deficits in pediatric frontal lobe epilepsy

Executive dysfunction and behavioral problems are common in children with epilepsy. Inhibition and shifting, both aspects of cognitive control, seem related to behavior problems and are thought to be driven mainly by the frontal lobes. We investigated if inhibition and shifting deficits are present in children with frontal lobe epilepsy (FLE). Secondly, we studied the relationship between these deficits and behavior problems. Thirty-one children were administered the Stroop Color Word Test and a digital version of the Wisconsin Card Sorting Test (WCST). Parents completed the Behavioral Rating Inventory for Executive Function (BRIEF) and the Achenbach scale (Child Behavior Checklist (CBCL)). About 20% of the children displayed significant low results on the Stroop Effect. About 60% showed shifting problems on the WCST. Parents reported cognitive control and behavioral deficits in about a third of the children. Also, behavioral problems and deficits in inhibition and shifting in daily life (BRIEF) seem to be related. There were no correlations between questionnaires and the Stroop and the WCST. Only in the group of children with many perseverative errors there were especially high correlations between Inhibit of the BRIEF

A Novel Malonamide Periodic Mesoporous Organosilica (PMO) for tuneable ibuprofen release

Incorporation of organic functionalities within porous materials is a very elegant manner to control the administration of therapeutic drugs. Delayed drug-release profile originates from weak and reversible interactions (e.g., electrostatic, hydrophobic–hydrophobic and H-bonding interaction) between the modified carrier and the drug molecule. Two new silsesquioxane PMO precursors were synthesized in a quick and facile Schotten-Baumann reaction of (3-aminopropyltriethoxy)silane and (N-methyl-3-aminopropyltrimethoxy)-silane with malonylchloride, respectively. Based on these bis(3-(triethoxysilyl)propyl)malonamide (MA) and N,N-dimethyl-N,N-bis(3-(triethoxysilyl)propyl)malonamide (mMA) precursors, an extensive range of 2D hexagonal PMOs with high functional loading was obtained by the co-condensation with tetraethyl orthosilicate (TEOS) in a typical PMO synthesis (acidic medium, P123, KCl). The materials showed good ordering up to 20 mol% of functional loading, a large surface area (up to 550 m2/g) and wide pores (∼7 nm). The malonamide-type PMOs are capable to adsorb large amounts of ibuprofen (130 mg/g) as a hydrophobic model drug. Release experiments are performed in a phosphate buffer solution at pH 7.4 and show a controlled desorption of Ibuprofen over 24 hours; a largely expanded times pan compared to mesoporous silicas. Moreover, we are able to tune the release profile by varying the content of organic bridges in the PMO pores