Browsing by Author "Marais Patrick"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Open Access
    No universal support for solar glare as an evolutionary driver of malar stripes in falcons
    (2023) Vrettos, Michelle; Amar, Arjun; Marais Patrick
    The paired dark malar or moustachial stripes of falcons (Falco spp.) are putatively adaptive plumage features whose function and evolutionary significance are poorly understood, and have rarely been investigated in published literature. A popular hypothesis for the function of falcon malar stripes is that they serve as antiglare devices, with the dark pigment absorbing visionimpeding solar glare and thereby improving the falcon's ability to visually detect and target prey in bright conditions. Correlative evidence from Peregrine Falcons (Falco peregrinus) provides support for this hypothesis, with a previous study finding that the size and prominence of malar stripes in this species correlate positively with solar radiation across the species' geographic range. In the present study, I extend the methodology used in this previous research to all extant species in the genus Falco, to determine both whether other falcon species display similar intraspecific trends, and whether differences in solar radiation conditions, in conjunction with species ecology, explain interspecific variation in falcon malar stripe characteristics. My results indicated that malar stripe characteristics were not positively related to solar radiation in the majority of species, with only the Peregrine Falcon showing reliable trends towards larger and darker malar stripes in individuals inhabiting regions of higher solar radiation. Likewise, solar radiation was not positively related to interspecific variation in falcon malar stripe characteristics, even after accounting for differences in body size, agility, prey base, and habitat between species. These results suggest that falcon malar stripes do not universally function as antiglare devices, at least in species other than the Peregrine Falcon. Malar stripes thus likely evolved in falcons for a different purpose (such as crypsis or social signaling), but may have become exapted for solar glare reduction in Peregrine Falcons owing to the species' cosmopolitan distribution and high degree of specialization on agile bird prey.
  • No Thumbnail Available
    Item
    Open Access
    Particle selection and parameterisation in virtual reality
    (2024) Keren, Gil Boaz; Gain, James; Marais Patrick
    This dissertation investigates the application of Virtual Reality (VR) technology in enhancing the selection and parameterisation of astronomical data compared to traditional desktop environments. Through the development and evaluation of the Immersive Data Visualisation Interactive Explorer for Particle Rendering (iDaVIE-p), a novel software application designed for both VR and desktop interfaces, this study explores VR's potential to improve accuracy, efficiency, and user experience in scientific research, particularly in astronomy, where datasets are large and complex. The primary focus of this research is to establish whether VR technology surpasses desktop environments in terms of task performance metrics such as accuracy, efficiency, usability, workload, and flow and how parameter tuning influences these metrics. Our experimental design involves a hybrid of within and between-subject comparison, engaging participants in tasks that require selecting and adjusting parameters of celestial objects represented as particles. Participants utilised the iDaVIE-p software in both VR and desktop, providing feedback through established questionnaires like the System Usability Scale, NASA Task Load Index, and Flow State Scale. The results indicate that while accuracy remained comparable between VR and desktop interfaces, VR significantly enhanced efficiency, with tasks completed 28% faster on average. Additionally, VR outperformed desktop in usability, workload, and flow metrics, evidencing a more engaging and less taxing experience. Surprisingly, these benefits were realized even among participants with limited VR experience, underscoring VR's intuitive interaction with three-dimensional (3D) environments. However, the study found mixed outcomes regarding parameter tuning, showing minor improvements in accuracy but a similar minor decrease in efficiency, suggesting a possible tradeoff between the two and that further research is needed to optimise parameter adjustments for task performance. This dissertation underscores VR's transformative potential in scientific research, offering insights into its advantages over traditional desktop interfaces for interacting with complex, 3D datasets. The findings advocate for the broader adoption of VR technology in scientific settings where tasks and datasets are 3D, as was in our case, highlighting its capacity to enhance user satisfaction, efficiency, and engagement in data selection tasks.