Correlates of leaf optical properties in tropical forest sun and extreme-shade plants

Thirteens hade-adaptedr ain forest species were comparedw ith twelve sun-adaptedt ropical forest species for correlates to leaf optical properties (described previously in Amer. J. Bot. 73: 1100-1108). The two samples were similar in absorptance of quanta for photosynthesis, but the shade-adaptedt axa: 1) had significantlyl ower specificl eaf weights,i ndicatinga more metabolically efficient production of surface for quantum capture; 2) synthesized less chlorophyll per unit area; and 3) used less chlorophyll for capturing the same quanta for photosynthesis. The anatomical features that best correlate with this increased efficiency are palisade cell shape and chloroplast distribution. Palisade cells with more equal dimensions have more chloroplasts on their abaxial surfaces. This dense layer of chloroplasts maximizes the light capture efficiency limited by sieve effects. The more columnar palisade cells of sun-adapted taxa allow light to pass through the central vacuoles and spaces between cells, making chloroplasts less efficient in energy capture, but allowing light to reach chloroplasts in the spongy mesophyll. Pioneer species may be an exception to these two groups of species. Three pioneer taxa included in this study have columnar palisade cells that are extremely narrow and packed closely together. This layer allows little penetration of light, but exposure of the leaf undersurface may provide illumination of spongy mesophyll chloroplasts in these plants.

Leaf Optical Properties of Rainforest Sun and Extreme Shade Plants

The opticalp ropertieso f the leaves of twelve tropicals un speciesa nd thirteent ropicale xtreme shade species were examinedw ith an integratings pherea ttachedt o a spectroradiometerM. easurements of diffuse reflectance and transmittance allowed calculations of absorptance, 350- 1,100 nm. Althoughs ome shade species absorbedh igherp ercentageso f quantumf lux densities for photosynthesis (400-700 nm, PPFD) than the mean for the sun species, the sun and shade species as groups were not significantly different from each other: 90.2, S.D. 3.6% for shade species and 88.6, S.D. 2.4% for the sun species. The groups of species did not differ in total absorptance of energy 350-1,100 nm. Furthermore, the sun and shade species were identical in theirs hifto f absorptancea t wavelengthsb etween6 50 and 750 nm. The anthocyanicc oloration of the leaf undersurfaceso f two species polymorphicf or this characteristic( Trionela hirsuta and Ischnosciphonp ruinosus)i s correlatedw ith increaseda bsorptancea t the uppere nd of the action spectrum of photosynthesis. Although sun and shade species have similar optical properties, the energy investment (as documented by dry wt per unit area of leaf surface) is much less for the shade species.

Eden in the age of the fifth sun: The narrative work of Homero Aridjis

Homero Aridjis (b. 1940) is a major Mexican poet, novelist, essayist and ecological activist whose prolific body of work, ranging over forty years and including more than eleven volumes of poetry and thirteen novels, has yet to be studied as a coherent literary corpus in the context of recent Latin American fiction. The purpose of this dissertation was to analyze the narrative works of this author as both illustrative of the changes that have occurred in Latin American fiction since the 1960s when it first burst onto the world scene, as well as to study the uniqueness of this particular author's view of literature as it relates to historical discourse, apocalypticism. and social commitment. ^ Research showed that in the case of the narrative style of Aridjis, major trends in the contemporary Latin American novel were present in such a profuse and model manner as to confirm this author's importance as a prime example of what is commonly known as “Post-Boom” fiction. However, beyond the mere presence of literary elements, this study showed that the author's unique approach to narrative style has altered and expanded the aesthetic and thematic possibilities of the contemporary novel. The area where this is most clearly seen is in his experimentation with the historical genre. By manipulating the referential techniques of what has lately come to be known as the “new historical novel,” Aridjis has written both a cycle of purely historical novels and a cycle of futuristic ones that attempt to transcend the temporal limits traditionally imposed by these narrative forms, fusing them into one constant questioning of the nature of love, hate and identity. In this manner, he has developed a “simultaneist” narrative approach where distinct historical and imagined periods, places, people, things, and texts coexist and interact, widening almost to delirium the interpretative possibilities of the work. ^ This unique view of time and narrative, together with the author's political activism and millenarian view of history, make the novels of Homero Aridjis an important element in understanding the continuing development and evolution of Latin American fiction at the turn of the century. ^

Voting with their feet: Migration, partisanship, and party-safe elections in Florida

Political scientists have long noted that Congressional elections are often uncompetitive, often extremely so. Many scholars argue that the cause lies in the partisan redistricting of Congressional districts, or “gerrymandering”. Other scholars emphasize polarization created by a fragmented news media, or the candidate choices made by a more ideological primary electorate. All these explanations identify the cause of party-safe elections in institutions of various kinds. This dissertation, by contrast, presents a structural explanation of uncompetitive elections. My theory is that population composition and patterns of migration are significant causes and predictors of election results in Florida. I test this theory empirically by comparing the predictions from four hypotheses against aggregate data, using the county as the unit of analysis. The first hypothesis is that Florida can be divided into clearly distinguishable, persistent partisan sections. This hypothesis is confirmed. The second hypothesis is that Florida voters have become increasingly partisan over time. This hypothesis is confirmed. The third hypothesis is that the degree of migration into a county predicts how that county will vote. This hypothesis is partially confirmed, for the migration effect appears to have waned over time. The last hypothesis is that the degree of religiosity of a county population is a predictor of how that county will vote. This hypothesis is also supported by the results of statistical analysis. By identifying the structural causes of party-safe elections, this dissertation not only broadens our understanding of elections in Florida, but also sheds light on the current polarization in American politics.

Organizational Behavior: Forgotten Variable in Safe Food

The war on foodborne illness in hotels and restaurants is based on microbiology and critical control points. The author argues that cooks, managers, instructors, researchers, and regulators need to start looking beyond this narrow base to include more organizational behavior processes in their arsenal.

Personnel selection, safety performance, and job performance: Are safe workers better workers?

The present dissertation consists of two studies that combine personnel selection, safety performance, and job performance literatures to answer an important question: are safe workers better workers? Study 1 tested a predictive model of safety performance to examine personality characteristics (conscientiousness and agreeableness), and two novel behavioral constructs (safety orientation and safety judgment) as predictors of safety performance in a sample of forklift loaders/operators (N = 307). Analyses centered on investigating safety orientation as a proximal predictor and determinant of safety performance. Study 2 replicated Study 1 and explored the relationship between safety performance and job performance by testing an integrative model in a sample of machine operators and construction crewmembers (N = 323). Both Study 1 and Study 2 found conscientiousness, agreeableness, and safety orientation to be good predictors of safety performance. While both personality and safety orientation were positively related to safety performance, safety orientation proved to be a more proximal determinant of safety performance. Across studies, results surrounding safety judgment as a predictor of safety performance were inconclusive, suggesting possible issues with measurement of the construct. Study 2 found a strong relationship between safety performance and job performance. In addition, safety performance served as a mediator between predictors (conscientiousness, agreeableness and safety orientation) and job performance. Together these findings suggest that safe workers are indeed better workers, challenging previous viewpoints to the contrary. Further, results implicate the viability of personnel selection as means of promoting safety in organizations.^

GIS-integrated mathematical modeling of social phenomena at macro- and micro- levels—a multivariate geographically-weighted regression model for identifying locations vulnerable to hosting terrorist safe-houses: France as case study

Adaptability and invisibility are hallmarks of modern terrorism, and keeping pace with its dynamic nature presents a serious challenge for societies throughout the world. Innovations in computer science have incorporated applied mathematics to develop a wide array of predictive models to support the variety of approaches to counterterrorism. Predictive models are usually designed to forecast the location of attacks. Although this may protect individual structures or locations, it does not reduce the threat—it merely changes the target. While predictive models dedicated to events or social relationships receive much attention where the mathematical and social science communities intersect, models dedicated to terrorist locations such as safe-houses (rather than their targets or training sites) are rare and possibly nonexistent. At the time of this research, there were no publically available models designed to predict locations where violent extremists are likely to reside. This research uses France as a case study to present a complex systems model that incorporates multiple quantitative, qualitative and geospatial variables that differ in terms of scale, weight, and type. Though many of these variables are recognized by specialists in security studies, there remains controversy with respect to their relative importance, degree of interaction, and interdependence. Additionally, some of the variables proposed in this research are not generally recognized as drivers, yet they warrant examination based on their potential role within a complex system. This research tested multiple regression models and determined that geographically-weighted regression analysis produced the most accurate result to accommodate non-stationary coefficient behavior, demonstrating that geographic variables are critical to understanding and predicting the phenomenon of terrorism. This dissertation presents a flexible prototypical model that can be refined and applied to other regions to inform stakeholders such as policy-makers and law enforcement in their efforts to improve national security and enhance quality-of-life.