Effects of irradiance and spectral quality on leaf structure and function in seedlings of two Southeast Asian Hopea species

We studied the development of leaf characters in two Southeast Asian dipterocarp forest trees under different photosynthetic photon flux densities (PFD) and spectral qualities (red to far-red, R:FR). The two species, Hopea helferi and H. odorata, are taxonomically closely related but differ in their ecological requirements; H. helferi is more drought tolerant and H. odorata more shade tolerant. Seedlings were grown in replicated shadehouse treatments of differing PFD and R:FR. We measured or calculated (1) leaf and tissue thicknesses; (2) mesophyll parenchyma, air space, and lignified tissue volumes; (3) mesophyll air volumes (Vmes/Asurf) and surfaces (Ames/Asurf); (4) palisade cell length and width; (5) chlorophyll/cm2 and a/ b; (6) leaf absorption; and (7) attenuance/absorbance at 652 and 550 nm. These characters varied in response to light conditions in both taxa. Characters were predominantly affected by PFD, and R:FR slightly influenced many characters. Leaf characters of H. odorata were more plastic in response to treatment conditions. Characters were correlated with each other in a complex fashion. Variation in leaf anatomy is most likely a consequence of increasing leaf thickness in both taxa, which may increase mechanical strength and defense against herbivory in more exposed environments. Variation in leaf optical properties was most likely affected by pigment photo-bleaching in treatments of more intense PFD and was not correlated with Amax. The greater plasticity of leaf responses in H. odorata helps explain the acclimation over the range of light conditions encountered by this shade-tolerant taxon. The dense layer of scales on the leaf undersurface and other anatomical characters in H. helferi reduced gas exchange and growth in this drought-tolerant tree.

The effects of a General Instructional Strategies course on the utilization of effective instructional strategies by teachers

The focus of this study was to explain the extent to which theoretically effective teaching strategies taught in a course on generic instructional strategies are being implemented by teachers in their actual teaching practice. ^ A multivariate causal-comparative (ex-post-facto) design was used to answer the research question. A teacher observation protocol, the General Instructional Strategies Analysis (GISA) was constructed and used to assess the utilization of instructional strategies in the classroom. The data of this study also included open-ended field notes taken during observations. ^ Multivariate Analyses of Variance (MANOVA) was used to compare the teaching strategies (set, effective explanation, hands-on activity, cooperative learning activity, higher order questioning, closure) of the group who had taken a general instructional strategies course (N=36) and the group who had not (N=36). Results showed a statistically significant difference between the two groups. The group who had taken the course implemented these strategies more effectively in almost all categories of effective teaching. Follow-up univariate tests of the dependent variables showed significant differences between the two groups in five of the six areas (hands-on activity being an exception). A second MANOVA compared the two groups on the effective use of attending behaviors (teacher movement/eye contact/body language/physical space, brief verbal acknowledgements/voice inflection/modulation/pitch, use of visuals, prompting/probing, praise/feedback/rewards, wait-time I and II). Results also showed a multivariate difference between the two groups. Follow-up univariate tests on the related dependent variables showed that five of the six were significantly different between the two groups. The group who had taken the course implemented the strategies more effectively. An analysis of the field notes provided further evidence regarding the pervasiveness of these differences between the teaching practices of the two groups. ^ It was concluded that taking a course in general instructional strategies increases the utilization of effective strategies in the classroom by teachers. ^

The interactive effects of predators, resources, and disturbance on freshwater snail populations from the Everglades

The origins of population dynamics depend on interplay between abiotic and biotic factors; the relative importance of each changing across space and time. Predation is a central feature of ecological communities that removes individuals (consumption) and alters prey traits (non-consumptive). Resource quality mitigates non-consumptive predator effects by stimulating growth and reproduction. Disturbance resets predator-prey interactions by removing both. I integrate experiments, time-series analysis, and performance trials to examine the relative importance of these on the population dynamics of a snail species by studying a variety of their traits. A review of ninety-three published articles revealed that snail abundance was much less in the Everglades and similar ecosystems compared to all other freshwater ecosystems considered. Separating consumptive from non-consumptive (cues) predator effects at different phosphorous levels with an experiment determined that phosphorous stimulated, but predator cues inhibited snail growth (34% vs. 23%), activity (38% vs. 53%), and reproductive effort (99% vs. 90%) compared to controls. Cues induced taller shells and smaller openings and moved to refugia where they reduced periphyton by 8%. Consumptive predator effects were minor in comparison. In a reciprocal transplant cage experiment along a predator cue and phosphorous gradient created by a canal, snails grew 10% faster and produced 37% more eggs far from the canal (fewer cues) when fed phosphorous-enriched periphyton from near the canal. Time-series analysis at four sites and predator performance trials reveal that phosphorous-enriched regions support larger snail populations, seasonal drying removes snails at all sites, crayfish negatively affect populations in enriched regions, and molluscivorous fish consume snails in the wet season. Combining these studies reveals interplay between resources, predators, and seasonality that limit snail populations in the Everglades and lead to their low abundance compared to other freshwater ecosystems. Resource quality is emerging as the critical factor because improving resources profoundly improved growth and reproduction; seasonal drying and predation become important at times and places. This work contributes to the general understanding in ecology of the relative importance of different factors that structure populations and provides evidence that bolsters monitoring efforts to assess the Comprehensive Everglades Restoration Plan that show phosphorous enrichment is a major driver of ecosystem change.

EFFECTS OF A VISUAL HORIZON ON DROSOPHILA MELANOGASTER OBJECT-TRACKING RESPONSES

To navigate effectively in three-dimensional space, flying insects must approximate distances to nearby objects. Humans are able to use an array of cues to guide depth perception in the visual world. However, some of these cues are not available to insects that are constrained by their rigid eyes and relatively small body size. Flying fruit flies can use motion parallax to gauge the distance of nearby objects, but using this cue becomes a less effective strategy as objects become more remote. Humans are able to infer depth across far distances by comparing the angular distance of an object to the horizon. This study tested if flying fruit flies, like humans, use the relative position of the horizon as a depth cue. Fruit flies in tethered flight were stimulated with a virtual environment that displayed vertical bars of varying elevation relative to a horizon, and their tracking responses were recorded. This study showed that tracking responses of the flies were strongly increased by reducing the apparent elevation of the bar against the horizon, indicating that fruit flies may be able to assess the distance of far off objects in the natural world by comparing them against a visual horizon.

New trends in health architecture for children and the effects of the built environment on young patients

The objective of this thesis was to investigate the effects of the built environment on the outcome of young patients. This investigation included recent innovations in children's hospitals that integrated both medical and architectural case studies as part of their design issues. In addition, the intervention responded to man-made conditions and natural elements of the site. The thesis project, a Children's Rehabilitation Hospital, is located at 1500 N.W. River Drive in Miami, Florida. The thesis intervention emerged from a site analysis that focused on the shifting of the urban grid, the variation in scale of the immediate context and the visual-physical connection to the river's edge. Furthermore, it addressed the issues of overnight accommodation for patient's families, as well as sound control through the use of specific materials in space enclosures and open courtyards. The key to the success of this intervention lies in the special attention given to the integration between nature and the built environment. Issues such as the incorporation of nature within a building through the use of vistas and the exploitation of natural light through windows and skylights, were pivotal in the creation of a pleasant environment for visitors, employees and young patients.

User Effects on Wearable Conformal SCMR System

The performance of a compact, wearable Conformal Strongly Coupled Magnetic Resonance (CSCMR) system is studied when the antenna is in the air and is worn on a user’s arm. The wireless powering system consists of the receiver and load elements designed on a printed circuit board that is attached to a polyester fabric band. The wearable antenna achieves high efficiency, has a small volume, and can be easily printed on substrates. Although the user effect on mobile terminal antennas has been studied in detail, absorption losses in wearable antennas have not been widely investigated. Our results show that efficiency of the antenna in free space is 70% and on a user’s arm is 50%. Human tissue in the close proximity of our wearable Conformal SCMR caused a decrease in radiated efficiency and total efficiency. This undesired degradation in antenna efficiency might be attributed to body loss and absorption losses. Our findings can be used as a reference for future studies on wearable devices and their applications, such as health and sports monitoring.