Leaf Optical Responses to Light and Soil Nutrient Availability in Temperature Deciduous Trees

Leaf optical parameters influence light availability at the cellular, leaf, and canopy scale of integration. While recent studies have focused on leaf optical responses to acute plant stress, the effects of changes in plant resources on leaf optics remain poorly characterized. We examined leaf optical and anatomical responses of five temperate deciduous tree species to moderate changes in nutrient and light availability. Spectral reflectance in the visible waveband generally increased at high light, but decreased with increased nutrient availability. Patterns of both spectral reflectance and absorptance were primarily determined by chlorophyll concentration although carotenoid concentration was also influential. While most anatomical features did not explain residual variation in reflectance, cuticle thickness was significantly related to reflectance at complementary angles compared to the angle of incidence. Absorptance did not change with light environment; however, absorption efficiency per unit biomass increased by approximately 40% under low light, due to reduced leaf mass per area. We conclude that changes in resource availability differentially influence leaf optical properties and that such changes are driven primarily by changes in pigment concentrations. The magnitude of leaf optical responses to moderate changes in resource availability was comparable to those of acute stress responses and varied among species

Spectroscopic Studies of Brooker\u27s Merocyanine in Zeolite L

Zeolites are porous, crystalline substances that have very unique atomic organizations which allow for the formation of complex channels within the crystals. Each type of zeolite has a distinct shape and structure. To better understand the properties of zeolite channels, a dye molecule known as Brooker’s merocyanine was inserted into Zeolite L. Maximum dye loading into the zeolite channels was achieved by altering different experimental variables, such as heat, solution concentration, stirring, cation exchange, and light exposure. X-ray diffraction was used to verify the synthesis of zeolites, the cation exchange process, and dye loading. UV-Vis spectroscopy was used to measure the amount of dye adsorbed by the zeolite. By using the UV-Vis absorbance values and Beer’s Law, the concentration of dye in the zeolites was determined. The results showed that an increase of heat and stirring correlated to an increase of adsorption of dye by the zeolite. Due to the light sensitivity of Brooker’s merocyanine, it was found that limiting the amount of light exposure of the dye solutions also resulted in higher dye adsorption by the zeolites. An increase of the concentration of the dye solution increased the rate of adsorption in the channels. However, exchanging the potassium ions found within the synthesized Zeolite L channels with smaller hydrogen ions did not have an affect on the adsorption of dye in the channels. Characterizing how to achieve a maximum of dye adsorption in the zeolites allows for a better understanding of how dye molecules interact within the zeolite channels

Examining the Correlation Between Childhood Trauma and Suicidal Ideation among Air Force Airmen

For decades, the United States military has been concerned about high suicide rates. Due to the increasing suicide rate within the armed forces, the need to better understand suicide-associated factors such as childhood trauma exposure is imperative. It is important to identify the research gaps that exist for promoting understanding of suicide and suicidal behavior and to enhance identification of those at risk for suicide. While there have been many published studies on the topic, conspicuously absent are studies that have included U.S. Air Force personnel. This research will examine the correlation between childhood trauma and suicidal ideation among Air Force airmen. The questions addressed in this review are (a) Is there a relationship between types of adverse childhood experiences and suicidal ideation among Air Force airmen? and (2) Is there a relationship between military assignments and suicidal ideation among Air Force airmen? The literature reviewed highlights the association between childhood trauma exposures and the risk of suicidal behaviors and the procedures proposed for the study provide directions for identifying those associations among Air Force airmen

Edaphic Specialization in Tropical Trees: Physiological Correlates and Responses to Reciprocal Transplantation

Recent research has documented the importance of edaphic factors in determining the habitat associations of tree species in many tropical rain forests, but the underlying mechanisms for edaphic associations are unclear. At Sepilok Forest Reserve, Sabah, Malaysian Borneo, two main soil types derived from sandstone (ridges) and alluvium (valleys) differ in nutrient and water availability and are characterized by forests differing markedly in species composition, structure, and understory light availability. We use both survey and reciprocal transplants to examine physiological adaptations to differences in light, nutrient, and water availability between these soil types, and test for the importance of resource-use efficiency in determining edaphic specialization. Photosynthetic surveys for congeneric and confamilial pairs (one species per soil type) of edaphic specialists and for generalists common to both soil types show that species specializing on sandstone derived soil had lower stomatal conductance at a given assimilation rate than those occurring on alluvial soil and also had greater instantaneous and integrated water-use efficiencies. Foliar dark respiration rates per unit photosynthesis were higher for sandstone ridge than alluvial lowland specialists. We suggest that these higher respiration rates are likely due to increases in photosynthetic enzyme concentrations to compensate for lower internal CO2 concentrations resulting from increased stomatal closure. This is supported by lower photosynthetic nitrogen-use efficiencies in the sandstone ridge specialists. Generalist species had lower water-use efficiencies than sandstone ridge specialists when growing on the drier, sandy ridgetops, but their nitrogen-use efficiencies did not differ from the species specialized to the more resource-rich alluvial valleys. We varied light environment and soil nutrient availability in a reciprocal transplant experiment involving two specialist species from each soil type. Edaphic specialist species, when grown on the soil type for which they were not specialized, were not capable of acclimatory shifts to achieve similar resource-use efficiencies as species specialized to that soil type. We conclude that divergent water-use strategies are an important mechanism underlying differences in edaphic associations and thus contributing to maintenance of high local tree species diversity in Bornean rain forests

Teacher effects on social/behavioral skills in early elementary school

Though many recognize that social and behavioral skills play an important role in educational stratification, no studies have attempted to estimate teachers’ effects on these outcomes. Using data from the Early Childhood Longitudinal Study–Kindergarten Cohort (ECLS–K), we estimate teacher effects on social and behavioral skills as well as on academic achievement. Teacher effects on social and behavioral skill development are sizeable, and are somewhat larger than teacher effects on academic development. Because—as we show—social and behavioral skills have a positive effect on the growth of academic skills in the early elementary grades, the teachers who are good at enhancing social and behavioral skills provide an additional indirect boost to academic skills in addition to their direct teaching of academic skills. Like previous studies we find that observable characteristics of teachers and the instructional approaches utilized in their classrooms are weak predictors of teacher effects. However, our results suggest that the teachers who produce better than average academic results are not always the same teachers who excel in enhancing social and behavioral skills

Social/behavioral skills and the gender gap in early educational achievement

Though many studies have suggested that social and behavioral skills play a central role in gender stratification processes, we know little about the extent to which these skills affect gender gaps in academic achievement. Analyzing data from the Early Child Longitudinal Study-Kindergarten Cohort, we demonstrate that social and behavioral skills have substantively important effects on academic outcomes from kindergarten through fifth grade. Gender differences in the acquisition of these skills, moreover, explain a considerable fraction of the gender gap in academic outcomes during early elementary school. Boys get roughly the same academic return to social and behavioral skills as their female peers, but girls retain an advantage both because they begin school with more advanced social and behavioral skills, and because their skill advantage grows over time. While part of the effect may reflect an evaluation process that rewards students who better conform to school norms, our results imply that the acquisition of social and behavioral skills enhances learning as well. Our results call for a reconsideration of the family and school-level processes that produce gender gaps in social/behavioral skills and the advantages they confer for academic and later success

Leveraging the Science of Learning to Enhance Student Success: An Application of Syfr Learning’s Principles of Practice

The purpose of the current article is to describe a set of empirically validated principles of practice with the potential to enhance student learning and academic performance. Specifically, we provide an overview of Syfr Learning’s principles of practice – a collection of scalable instructional techniques derived from decades of research in the domain of learning science. Further, we provide an illustrative example of the benefits of Syfr Learning’s principles of practice when incorporated into existing curricula in a K-12 setting