Evaluating forest restoration effects on timing of avian dawn chorus in Ranomafana National Park, Madagascar

Monitoring of forest restoration efforts is essential to ensure healthy, self-sustaining tropical rainforests. Passive acoustic monitoring is used to monitor vocal activity of birds, which play a key role in forest ecosystems as seed dispersers. Communication between birds seems most profitable during a peak of bird singing in the morning, known as the dawn chorus. Anthropogenic disturbances leading to increased light levels affect the timing of this chorus in individual species. This research sheds a light on the effect of forest restoration on the dawn chorus using automatic detection methods to identify bird sounds from acoustic data. Machine learning methods like clustering and pattern matching were used alongside a manual analysis to describe the dawn chorus in protected forests as well as restoration sites around Ranomafana National Park, Madagascar. Restoration sites were found to have lower species richness and increased interference from insect sounds. No difference was found between timing of the dawn chorus in both forest habitats. This can possibly be assigned to changes in community composition and decreased detectability of species in insect-dominated landscapes. Future research could further disentangle these effects, by filtering of acoustic data, development of workflow pathways and the use of stronger machine learning methods that allow for more reliable species-specific detection. In the current state of automatic acoustic methods, close cooperation with local experts is recommended to achieve effective monitoring in tropical rainforests

Optically responsive switches:understanding and improving photochromic properties

Fotochromische moleculaire schakelaars zijn moleculen die heen en weer kunnen worden geschakeld tussen twee of meer isomeren door middel van light waarbij deze isomeren verschillend van kleur zijn. In de laatste decennia is er veel aandacht geweest voor het fenomeen fotochromisme vanwege de potentiële toepassingen. Dit omdat, behalve de kleurverandering, fotochromisch schakelen gepaard gaat met een verandering van veel andere eigenschappen van het molecuul, zoals de vorm, de geleidbaarheid, het redoxpotentiaal, en de polariteit. Er ontstaan hierdoor vele manieren waarop de schakelaar een effect kan hebben op zijn omgeving. Schakelaars kunnen hierdoor worden gebruikt voor het ontwikkelen van grotere moleculaire systemen die kunnen worden beïnvloed door licht. De belangrijkste onderwerpen in dit proefschrift zijn als volgt: - het fotochromische gedrag van een asymmetrische dithienyletheen moleculaire schakelaar in oplossing; - de oppervlakte-immobilisatie van symmetrische en asymmetrische dithienyletheen schakelaars, welke van grote invloed blijkt te zijn op het fotochemische gedrag van de asymmetrische schakelaars; - de synthese en oppervlakte-immobilisatie van een dithienyletheen schakelaar met een driepotige verbindingsgroep die is ontworpen om interacties tussen de schakelaar en het oppervlak te minimaliseren; - het gebruik van een chirale dithienyletheen als doteerstof in een vloeibaar kristal, welke leidt tot de vorming van een chirale (helische) fase met een spoed die door licht kan worden beïnvloed; - het onderzoek naar een computationele methode voor het bestuderen van de thermisch gedreven isomerisatie van sterisch sterk gehinderde alkenen en tweedegeneratie moleculaire motoren

The phonological awareness, written spelling and oral reading of learners in an inclusive English-medium education setting

There is a need for information regarding the relationship of phonological awareness to reading and spelling in the multilingual learner in South Africa. The speech-language therapist has a role to play as part of the collaborative team assessing and treating the learner with reading and spelling difficulties. The aim of the study was to examine the relationships that exist between phonological awareness, written spelling and oral reading abilities in four groups of school-aged learners. A quantitative research design was employed in the form of a descriptive survey. Twenty test subjects were selected randomly from Grade 2 classes at an English-medium inclusive school in Pretoria, South Africa. Their class teachers on their final school report of the year had rated the learners as having good or poor literacy ability. They were organized into four research groups which differed with respect to their home language (English or English as Additional Language) and with respect to their literacy ability as judged by their teachers (Good or Poor literacy ability). A questionnaire was designed to ascertain parental perspectives pertaining to the learners’ case history and literacy development. A test battery composed of the Goldman-Fristoe Test of Articulation (Goldman&Fristoe, 1986), the Phonological Assessment Battery (Frederickson, Reason&Frith, 1997), the ESSI Reading and the ESSI Spelling Test (Esterhuyse&Beukes, 1997), and the TOLD-P: 2 (Newcomer&Hammill, 1991), as well as a Class Spelling List and a Reading Comprehension Task developed by the researcher, was administered to all test subjects. Findings of subjects’ performance in this study supported international findings regarding the strong relationship between phonological awareness ability and performance on reading and spelling measures. In addition, multilingual learners in this study were found to have delays in language development that negatively impacted on their literacy rating. The language development of the English-speakers with poor literacy ability in this study also negatively affected their reading and spelling performance. The test battery used in this study, with the exception of the Reading Comprehension Task, proved useful in differentiating subjects with good and poor literacy abilities and appears to be applicable for use in the South African situation. The results provide useful insights for the assessment and treatment of these learners. Furthermore, relevant research topics in the field of literacy development in an inclusive education setting were presented.Dissertation (M (Communication Pathology))--University of Pretoria, 2005.Speech-Language Pathology and Audiologyunrestricte