Researchers analyze images in areas such as geology, bat cardiovascular systems and art studies to verify their observations. Some images are hard to study as their details are not vivid; hence there is a need to enhance these images to facilitate their study while preserving their contents. This study is aimed at assisting the researchers in the Cardiovascular Systems Dynamic Laboratory at Texas A&M University by evaluating the importance of Image Enhancement (IE) for improving visibility of features. For this study the images were collected and manipulated using various IE techniques and were shown to the novice researchers who were asked to perform three different tasks. These tasks were representative of the research work conducted in the lab. The techniques that were selected aimed at reducing the problems that are usually associated with data obtained from microscopic feeds. A customized application was developed to expedite and automate the study. The results indicated that the researchers did not immmensely benefit from the improved visualization for easy tasks. However, their performance improved for tasks that required more practice and skill. Our approach contributes towards designing an effective training program for novice researchers in the lab. Moreover, it is promising for similar research in different fields of study.

Males produce conspicuous advertisement signals to attract mates. These signals, however, often attract eavesdropping predators as well, so the benefit of obtaining a mate is balanced by the cost of an increased risk of predation. The evolution of sexual advertisement signals can be understood only through a thorough investigation of both predator and prey. The Neotropical bat, Trachops cirrhosus, feeds on frogs and uses frog mating calls to locate its prey. On the basis of frog calls alone, bats can assess which frogs are palatable and which are poisonous. The túngara frog, Physalaemus pustulosus, produces two types of calls, simple and complex. Both female frogs and frog-eating bats prefer complex calls to simple ones, and as a result, male frogs face opposing forces of sexual and natural selection. While there has been extensive study of mate choice behavior in the túngara frog, there has been comparatively little investigation of foraging behavior in the frog-eating bat. In my doctoral research, I investigate the sensory constraints and cognitive flexibility that shape foraging success in T. cirrhosus. Specifically, I address the following questions: (1) Are predator preferences for signal complexity influenced by localization performance? Do bats show better localization performance for complex calls than simple ones in silence, in noise, or in obstacles? (2) How fixed are predator associations for prey cues? Given novel foraging contexts, can predators rapidly track prey changes and alter pre-existing associations between prey cues and prey quality? (3) What mechanisms do predators use to learn about prey cues? Do social interactions play a role in prey acquisition behavior? My results show that while T. cirrhosus is limited by biophysical constraints in its ability to localize prey, within these constraints it shows surprising flexibility. It can rapidly alter associations between prey cues and prey quality, and can quickly acquire novel foraging behavior via social learning. Together these studies offer new insights on the role of eavesdropping predators in the evolution of their sexually advertising prey, and shed new light on the role of learning in foraging success. / text

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Thesis (M.E.M.)-Duke University, 2006. / Typescript (photocopy). Includes bibliographical references (leaves 48-53).

Thesis (M.S.)--University of Nevada, Reno, 2007. / "December, 2007." Includes bibliographical references. Online version available on the World Wide Web.

Global efforts to address climate change have recently introduced a new source of fatality risk to bats, from wind turbines. Bat fatalities have now been confirmed in varying magnitudes at wind energy facilities around the world. Research at large turbines and wind farms has started to produce a knowledge base regarding impacts upon bats, though many questions remain. Little, however, is known about risk levels at small and medium scale wind turbines. Equally, research regarding the impacts of turbines in the UK is limited. This thesis examines the impacts of small and medium scale wind turbines upon bats. Planning records of wind turbines in Wales and south west (SW) England were reviewed. Approved planning applications for single and double turbine sites were found to greatly outnumber those for larger scale wind farms. The large majority of single and double turbine approvals were also for small turbines. The potential impacts of turbine presence and density on current bat roost populations and population changes were analysed, finding no impact. An estimate of bat fatality rates at small and medium turbines was calculated, using a trained search dog to locate carcasses. An average fatality rate between 0.81 and 15.15 turbine-1 year-1 was estimated. The higher rate accounted for uncertainty in the monitoring protocol. Only 3 bat carcasses were however observed across all monitored turbines, suggesting more stringent monitoring would likely confirm a lower maximum annual fatality rate. Bat activity levels were also compared between the turbine location and differing habitat types. A disturbance effect was consequently identified in proximity to turbines during high wind speeds. Finally moderating influences of environmental weather and habitat conditions upon bat activity were confirmed. Social Network Analysis (SNA) methods were used to analyse bat movement networks within a small grid of bat detectors centred on each turbine. Associations were identified between bats’ movement routes and habitat structures present at sites, highlighting vulnerabilities to disruption. Furthermore bats actively used the turbine area, potentially for foraging purposes. Finally by assessing bats’ activity levels in response to a turbine noise playback experiment, small turbine noise was found to have no impact upon bat activity. Planning guidance regarding bats and small and medium turbines is highlighted as a priority for policy development.

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