Leaf Micromorphology Aids Taxonomic Delineation within the Hypervariable Genus Metrosideros (Myrtaceae) on O\u27ahu

Variation in leaf micromorphology can aid delimitation of taxonomically difficult groups. The woody genus Metrosideros (Myrtaceae) dominates Hawai\u27i\u27s native forests and comprises striking, predominantly infraspecific, macromorphological variation, including many forms unrecognized in current taxonomic treatments. On taxonomically rich O\u27ahu, 10 taxa (varieties or unnamed morphotypes of M. polymorpha and other species) occur in a predictable sequence with overlapping ranges from low to high elevation along the numerous leeward ridges of the Ko\u27olau Range. We used scanning electron and light microscopy to examine mature, nonsenescing sun leaves from each of these 10 taxa. Parametric and nonparametric tests were used to compare stomatal complex (SC) traits and those of a newly described secretory structure (SS) across taxa. Correlations among traits and discriminant analyses were also done. Density and length of SCs were inversely related overall, and both measures varied significantly across taxa. Although abaxial SSs were consistently present only in the two highest-elevation glabrous taxa, adaxial SSs were present in all 10 taxa. Length and density of adaxial SSs and density of abaxial SSs varied across taxa, and densities of both SCs and SSs were greatest at high elevation. Combined, the SC and SS traits differentiated 100% of four glabrous varieties and two of three pubescent varieties of M. polymorpha. Variation in leaf micromorphology, including presence and density of a newly described SS, aids delimitation of closely related Hawaiian Metrosideros taxa and may refilect differential local adaptation across a heterogeneous landscape

Space station payload operations scheduling with ESP2

The Mission Analysis Division of the Systems Analysis and Integration Laboratory at the Marshall Space Flight Center is developing a system of programs to handle all aspects of scheduling payload operations for Space Station. The Expert Scheduling Program (ESP2) is the heart of this system. The task of payload operations scheduling can be simply stated as positioning the payload activities in a mission so that they collect their desired data without interfering with other activities or violating mission constraints. ESP2 is an advanced version of the Experiment Scheduling Program (ESP) which was developed by the Mission Integration Branch beginning in 1979 to schedule Spacelab payload activities. The automatic scheduler in ESP2 is an expert system that embodies the rules that expert planners would use to schedule payload operations by hand. This scheduler uses depth-first searching, backtracking, and forward chaining techniques to place an activity so that constraints (such as crew, resources, and orbit opportunities) are not violated. It has an explanation facility to show why an activity was or was not scheduled at a certain time. The ESP2 user can also place the activities in the schedule manually. The program offers graphical assistance to the user and will advise when constraints are being violated. ESP2 also has an option to identify conflict introduced into an existing schedule by changes to payload requirements, mission constraints, and orbit opportunities

Methodological Issues in Building, Training, and Testing Artificial Neural Networks

We review the use of artificial neural networks, particularly the feedforward multilayer perceptron with back-propagation for training (MLP), in ecological modelling. Overtraining on data or giving vague references to how it was avoided is the major problem. Various methods can be used to determine when to stop training in artificial neural networks: 1) early stopping based on cross-validation, 2) stopping after a analyst defined error is reached or after the error levels off, 3) use of a test data set. We do not recommend the third method as the test data set is then not independent of model development. Many studies used the testing data to optimize the model and training. Although this method may give the best model for that set of data it does not give generalizability or improve understanding of the study system. The importance of an independent data set cannot be overemphasized as we found dramatic differences in model accuracy assessed with prediction accuracy on the training data set, as estimated with bootstrapping, and from use of an independent data set. The comparison of the artificial neural network with a general linear model (GLM) as a standard procedure is recommended because a GLM may perform as well or better than the MLP. MLP models should not be treated as black box models but instead techniques such as sensitivity analyses, input variable relevances, neural interpretation diagrams, randomization tests, and partial derivatives should be used to make the model more transparent, and further our ecological understanding which is an important goal of the modelling process. Based on our experience we discuss how to build a MLP model and how to optimize the parameters and architecture.Comment: 22 pages, 2 figures. Presented in ISEI3 (2002). Ecological Modelling in pres

A review of the supply of liquid propellants and other fluids in support of the Space Shuttle Program

In this study, over twenty significant liquid propellants and other fluids were reviewed as to their supply in support of the Space Shuttle Program (SSP), primarily at KSC. The uniqueness of most of the products, either by their application or production characteristics, present a variety of supply issues to contend with. Each, however, is critical to the success of the SSP. It becomes necessary to formulate, and maintain, a logistic approach to assure a continued availability of each product. For convenience, two categories were established. One, labeled limited-availability, represents those products wherein they are single sourced, have production restrictions and/or there has been a history of supply problems. The other, labeled universally-available, is characteristic of those having several sources and/or having little, if any, historical supply problems. This last category was not examined in depth. Through concepts of establishing stockpile inventories, multiple supply contracts, or other arrangements, the supply of liquid propellants and other fluids can be assured

Protective Factors Among Postsecondary Students Enrolled in a First-Generation Program

For generations, researchers have examined attributes that contribute to the adaptability of low socioeconomic youth. Attributes that help one become resilient are known as protective factors. The purpose of this descriptive study was to explore the protective factor(s) that contributed to the enrollment of first-generation, low-socioeconomic status (SES) students at a southern land-grant university. The population consisted of postsecondary students in a First Scholars program during the 2015-2016 academic year. The authors examine the existing literature on the effects of low SES on postsecondary education in order to explore what assists these students in maintaining a steadfast behavior. Recommendations are made for the recruitment of students who display a higher resiliency to be successful at the postsecondary level and for the First Scholars program on how to further enhance the program

Stress and depression among veterinary medical students

While existing literature suggests that professional students (e.g., medical, dental, law, nursing, etc.) experience high levels of stress and depression, the experiences of veterinary medical students have been less well examined. The purpose of this study was to explore the levels of stress and depression among veterinary medical students and to examine the relationship between these variables. Study participants were 1,245 veterinary medical students from North America. The findings provide support for the assertion that veterinary medical students experience high levels of stress and depression. Results also indicated that there is a correlation between stress and depression for veterinary medical students and that female students experience higher levels of stress and depression than their male counterparts.Accepted manuscrip

A Deliberative Defense of Diversity: Moving Beyond the Affirmative Action Debate to Embrace a 21st Century View of Equality

"Diversity" is a recent construct in our equal protection jurisprudence, but during its relatively short existence it has garnered many critics. Even critical race scholars, the most vocal proponents of aggressive civil rights and equal protection enforcement, are skeptical about "diversity," to say nothing of its many opponents. Critiques of "diversity" argue that it is vague, an alter ego of affirmative action, and an inferior method of achieving the remedial purposes of equal protection abound. More troubling than this scholarly critique of diversity, however, is the "mixed motive" analysis of the diversity interest in the Court's equal protection jurisprudence that conflates the aspirational aims of diversity with the remedial aims of affirmative action. Diversity can and should be defended and materially distinguished from affirmative action both in the instrumentalist theories justifying it, as well as in the legal standards by which its constitutionality is evaluated. This Article offers that defense. The primary aim of this Article is to elucidate the "diversity interest," as recognized in our equal protection jurisprudence, through the lens of modern diversity practice. This corporate perspective on constitutional law may seem inapt. But viewing the constitutional diversity interest through the lens of modern diversity practice exposes the deficiency of our equal protection jurisprudence grounded solely in a remedial principle of equality to appropriately define or adequately accommodate the distinct aspirational aims of the diversity interest. Modern diversity practice offers insight and analogy for how our equal protection jurisprudence should respond to this deficiency, first by defining the various instrumentalist justifications for the diversity interest, and second by reframing the equal protection analysis to suit the constitutional contours of the diversity interest. Modern diversity practice offers both a theoretical and empirical defense of diversity that can help illuminate the legal analysis of diversity and move our equal protection jurisprudence from a backward-looking doctrine of redress to a forward-looking doctrine of egalitarianism