Development and Verification of a Flight Stack for a High-Altitude Glider in Ada/SPARK 2014

SPARK 2014 is a modern programming language and a new state-of-the-art tool set for development and verification of high-integrity software. In this paper, we explore the capabilities and limitations of its latest version in the context of building a flight stack for a high-altitude unmanned glider. Towards that, we deliberately applied static analysis early and continuously during implementation, to give verification the possibility to steer the software design. In this process we have identified several limitations and pitfalls of software design and verification in SPARK, for which we give workarounds and protective actions to avoid them. Finally, we give design recommendations that have proven effective for verification, and summarize our experiences with this new language

Predictive Effects of Parenting Styles, Self-Regulation, and Resistance to Peer Influence on Drinking Behaviors in College Freshmen: A Social Learning Perspective

The first year of college may be a salient time period for the development of drinking practices in college populations. While parenting styles have been associated with global self-regulation, resistance to peer influence and college student drinking behaviors, a comprehensive evaluation of these relationships has yet to be established. Researchers have demonstrated that self-regulation acts as both a predictor and moderator of resistance to peer influence, which has been shown to be a more proximal predictor of drinking behaviors. While relationships between global self-regulation, parenting and drinking have been empirically established, less attention has been given to specific methods of self-regulation, such as regulatory focus. Thus, the current study examined the relationships between parenting styles, two modes of regulatory focus (i.e., promotion and prevention focus), resistance to peer influence and drinking behaviors in first year college students. It was hypothesized that regulatory focus and resistance to peer influence would be partial mediators between parenting styles and drinking behaviors, such that parenting styles would predict regulatory focus, which would in turn predict resistance to peer influence; subsequently, peer influence would predict drinking behaviors. It was also hypothesized that each mode of regulatory focus would moderate the manner in which resistance to peer influence predicts drinking behaviors. Finally, given that researchers have also found race to be a common influential factor on all variables within the current study, racial differences across the aforementioned relationships were also examined. The current study sampled 323 college freshmen from a large southeastern college student population. A structural equation modeling approach was used to examine all variables of interest. Results indicated that that promotion-focused self-regulation and resistance to peer influence sequentially mediated relationships between authoritative and permissive parenting styles and drinking behaviors. Prevention focused self-regulation was not associated with resistance to peer influence; thus, these constructs did not sequentially mediate relationships between parenting and drinking behaviors. Results also indicated that when resistance to peer influence mediated the relationship between a given parenting style and drinking behavior, it was also moderated by a mode of regulatory focus. Finally, while race was not shown to moderate either sequential mediation model, the influence of race on individual constructs was shown to be moderated by regulatory focus. Results of this study further inform literature on the effects of social learning constructs on drinking behaviors within the first year of matriculating to college. These results also provided further knowledge on what social (i.e., parenting, peer influence) and internal (regulatory focus) components may be important targets in alcohol interventions for college freshmen

Always on the wing - Fluid dynamics, flight performance and flight behavior of common swifts

The aerodynamics and kinematics behind the flight of animals are relatively unknown. Although animal flight has been studied for several hundreds of years, it is only in recent time that we have the technical abilities to study the mechanistic basis of animal flight. This thesis represents an attempt to widen the knowledge about animal flight by studying one of the most advanced flyers of the natural world, the common swift (Apus apus). Common swifts, or swifts for short, are aerial insectivores that spend almost their entire lifetime on the wing. In paper I, the aerodynamics and kinematics of a swift in flapping cruising flight were studied in a wind tunnel. The results showed that the rotational strength, or circulation, of the vortices that were shed into the wake behind the bird varied in a very smooth manner, which was different from wakes previously described for other birds. In paper II, the wake of a swift in flapping flight was studied over a range of flight speeds. The results showed that the wake of the swift in addition to the features found in Paper I, consisted of a pair of trailing vortices behind the tail and the wing base. The fact that vortices are shed at the wing base suggests that the two wings operate, to some extent, aerodynamically detached from each other. In paper III, the gliding flight of a swift was examined. The results showed that the bird generated a simple wake, consisting of a pair of trailing wingtip and tail vortices. The gliding efficiency of the swift was found to be relatively high compared to other birds. In paper IV, swifts were studied in free flight using tracking radar during spring migration, autumn migration and when the birds sleep on the wing. The objective was to compare the birds’ flight speeds to predictions from flight mechanical theory. The results showed that the birds changed their flight speed between behaviors less than predicted from theory. In paper V, the swifts were studied in display flights, often called ‘screaming parties’. During these events, the birds appear to reach high speeds. The results showed that the birds flew on average at flight speeds twice the speed on migration, suggesting that the birds are capable of high power output during short bursts of anaerobic muscle work. In paper VI, the swifts’ ability to compensate for wind drift during migration was studied using tracking radar. The results showed that the birds compensated to a large extent for the winds, both by changing their heading direction and by increasing their airspeed. Increasing airspeed had been theoretically described previously as a possible wind response, but this study was the first to show this empirically

Subheap-Augmented Garbage Collection

Automated memory management avoids the tedium and danger of manual techniques. However, as no programmer input is required, no widely available interface exists to permit principled control over sometimes unacceptable performance costs. This dissertation explores the idea that performance-oriented languages should give programmers greater control over where and when the garbage collector (GC) expends effort. We describe an interface and implementation to expose heap partitioning and collection decisions without compromising type safety. We show that our interface allows the programmer to encode a form of reference counting using Hayes\u27 notion of key objects. Preliminary experimental data suggests that our proposed mechanism can avoid high overheads suffered by tracing collectors in some scenarios, especially with tight heaps. However, for other applications, the costs of applying subheaps---in human effort and runtime overheads---remain daunting

Compiling Irregular Software to Specialized Hardware

High-level synthesis (HLS) has simplified the design process for energy-efficient hardware accelerators: a designer specifies an accelerator’s behavior in a “high-level” language, and a toolchain synthesizes register-transfer level (RTL) code from this specification. Many HLS systems produce efficient hardware designs for regular algorithms (i.e., those with limited conditionals or regular memory access patterns), but most struggle with irregular algorithms that rely on dynamic, data-dependent memory access patterns (e.g., traversing pointer-based structures like lists, trees, or graphs). HLS tools typically provide imperative, side-effectful languages to the designer, which makes it difficult to correctly specify and optimize complex, memory-bound applications. In this dissertation, I present an alternative HLS methodology that leverages properties of functional languages to synthesize hardware for irregular algorithms. The main contribution is an optimizing compiler that translates pure functional programs into modular, parallel dataflow networks in hardware. I give an overview of this compiler, explain how its source and target together enable parallelism in the face of irregularity, and present two specific optimizations that further exploit this parallelism. Taken together, this dissertation verifies my thesis that pure functional programs exhibiting irregular memory access patterns can be compiled into specialized hardware and optimized for parallelism. This work extends the scope of modern HLS toolchains. By relying on properties of pure functional languages, our compiler can synthesize hardware from programs containing constructs that commercial HLS tools prohibit, e.g., recursive functions and dynamic memory allocation. Hardware designers may thus use our compiler in conjunction with existing HLS systems to accelerate a wider class of algorithms than before

The Ecology of a Tallgrass Treasure: Audubon’s Spring Creek Prairie

This book describes the major plant and animal components of Spring Creek Prairie Audubon Center, an 850-acre National Audubon Society tallgrass prairie in Lancaster County, southeastern Nebraska. In addition to providing a species list of the area’s plants (368 species), there are comprehensive annotated lists of its birds (240), mammals (43), reptiles (23), and amphibians (10). There are also variably complete annotated lists of the area’s butterflies (76), sphinx moths (30), silk moths (7), dragonflies (24), damselflies (11), grasshoppers (9), katydids (11), mantids (2), and walkingsticks (2). Brief profiles of life histories and ecologies of 55 animal and 7 plant species are included, as well as information on nearly 100 public-access native grasslands in eastern Nebraska. The text comprises more than 68,000 words, 400 references, and a glossary of 125 biological/scientific terms as well as more than 40 line drawings by the author. doi 10.13014/K25B00NKhttps://digitalcommons.unl.edu/zeabook/1066/thumbnail.jp

Characterisation of Nitric Oxide Synthase Activity in the Sea Anemone Aiptasia pallida and an Evaluation of Responses to Environmental Stress

Studies were undertaken to investigate the presence of nitric oxide synthase (NOS; E.C. 1.14.13.39) activity in number of cnidarian species from shallow marine subtropical environments. Enzyme activity was assayed by measuring the conversion of 3H L-arginine to 3H L-citrulline (the citrulline assay). This assay was shown to be sufficiently sensitive for studies of this nature but was not optimised for use with cnidarian preparations. As a result, confidence in the accuracy of the generated assay results is limited. NOS activity was nevertheless demonstrated in the sea anemone A. pallida, in the zooxanthellae associated with A. pallida, Symbiodinium spp. and in five scleractinian coral species. Preliminary studies were conducted to characterise NOS from A. pallida. NOS activity of this species was shown to be predominantly cytosolic and basal rates of enzyme activity were determined to be 0.47 ±0 - 9.96 ±0.06 pmoles citrulline µg proteinˉ¹ minˉ¹. The biochemical signature of the enzyme is defined by an apparent Km of 132.9 µM L-arginine and an apparent V max of 17.7 pmoles citrulline µg proteinˉ¹ minˉ¹. The NOS enzyme from A. pallida was inhibited by the arginine analogue L-NMA with an apparent K1 of 1014 µM. Histochemical localisation of NOS activity by NADPH-diaphorase staining showed the enzyme to be present in the epidermal cells and at the extremities of the mesoglea. The hypothesis that NOS has potential as an innovative biochemical effect biomarker in cnidarian species was investigated with a number of experiments. NOS activity levels were determined in A. pallida previously dosed with sublethal concentrations of copper, fluoranthene or tributyltin-oxide. No clear evidence to support this hypothesis was provided by these studies. Morphological responses of A. pallida were monitored during exposure to contaminants, arginine analogues, a nitric oxide donor and a thermal regime that induced bleaching. Contraction of tentacles and body columns was a noted response to each of these exposures; individuals exposed to the most extreme concentrations of chemicals or the highest temperature tested typically elicited the most extreme contraction responses. Exposure of A. pallida to temperatures gradually increasing from 25 to 35°C over 10 days induced bleaching characterised by reduced zooxanthellae densities. NOS activity levels and antioxidant capacity, both expressed in terms of per unit protein, were increased in anemones exposed to temperatures of > 31 °C. NOS and FRAP activities expressed on a per anemone basis showed no clear change over the experimental period despite the substantial declines in host protein noted in anemones over the experimental period. These results indicate that FRAP and NOS activity levels were maintained over the course of the applied experimental thermal regime despite the occurrence of dramatic physiological changes. Taken together, these results suggest that NOS plays an important role in the biology of cnidarians, and that as such, the activity of this enzyme has the potential to be developed into a valuable biomarker for the evaluation of initial responses of key organisms in tropical and subtropical marine ecosystems to adverse conditions. However, these results also reveal that a more comprehensive knowledge of both the roles played by NO and the responsiveness of NOS to a range of potentially adverse stimuli is required to fulfil this potential.Bermuda Biological Station for Researc

The Ecology of a Tallgrass Treasure: Audubon’s Spring Creek Prairie

This book describes the major plant and animal components of Spring Creek Prairie Audubon Center, an 850-acre National Audubon Society tallgrass prairie in Lancaster County, southeastern Nebraska. In addition to providing a species list of the area’s plants (368 species), there are comprehensive annotated lists of its birds (240), mammals (43), reptiles (23), and amphibians (10). There are also variably complete annotated lists of the area’s butterflies (76), sphinx moths (30), silk moths (7), dragonflies (24), damselflies (11), grasshoppers (9), katydids (11), mantids (2), and walkingsticks (2). Brief profiles of life histories and ecologies of 55 animal and 7 plant species are included, as well as information on nearly 100 public-access native grasslands in eastern Nebraska. The text comprises more than 68,000 words, 400 references, and a glossary of 125 biological/scientific terms as well as more than 40 line drawings by the author. doi 10.13014/K25B00NKhttps://digitalcommons.unl.edu/zeabook/1066/thumbnail.jp

A Language-centered Approach to support environmental modeling with Cellular Automata

Die Anwendung von Methodiken und Technologien aus dem Bereich der Softwaretechnik auf den Bereich der Umweltmodellierung ist eine gemeinhin akzeptierte Vorgehensweise. Im Rahmen der "modellgetriebenen Entwicklung"(MDE, model-driven engineering) werden Technologien entwickelt, die darauf abzielen, Softwaresysteme vorwiegend auf Basis von im Vergleich zu Programmquelltexten relativ abstrakten Modellen zu entwickeln. Ein wesentlicher Bestandteil von MDE sind Techniken zur effizienten Entwicklung von "domänenspezifischen Sprachen"( DSL, domain-specific language), die auf Sprachmetamodellen beruhen. Die vorliegende Arbeit zeigt, wie modellgetriebene Entwicklung, und insbesondere die metamodellbasierte Beschreibung von DSLs, darüber hinaus Aspekte der Pragmatik unterstützen kann, deren Relevanz im erkenntnistheoretischen und kognitiven Hintergrund wissenschaftlichen Forschens begründet wird. Hierzu wird vor dem Hintergrund der Erkenntnisse des "modellbasierten Forschens"(model-based science und model-based reasoning) gezeigt, wie insbesondere durch Metamodelle beschriebene DSLs Möglichkeiten bieten, entsprechende pragmatische Aspekte besonders zu berücksichtigen, indem sie als Werkzeug zur Erkenntnisgewinnung aufgefasst werden. Dies ist v.a. im Kontext großer Unsicherheiten, wie sie für weite Teile der Umweltmodellierung charakterisierend sind, von grundsätzlicher Bedeutung. Die Formulierung eines sprachzentrierten Ansatzes (LCA, language-centered approach) für die Werkzeugunterstützung konkretisiert die genannten Aspekte und bildet die Basis für eine beispielhafte Implementierung eines Werkzeuges mit einer DSL für die Beschreibung von Zellulären Automaten (ZA) für die Umweltmodellierung. Anwendungsfälle belegen die Verwendbarkeit von ECAL und der entsprechenden metamodellbasierten Werkzeugimplementierung.The application of methods and technologies of software engineering to environmental modeling and simulation (EMS) is common, since both areas share basic issues of software development and digital simulation. Recent developments within the context of "Model-driven Engineering" (MDE) aim at supporting the development of software systems at the base of relatively abstract models as opposed to programming language code. A basic ingredient of MDE is the development of methods that allow the efficient development of "domain-specific languages" (DSL), in particular at the base of language metamodels. This thesis shows how MDE and language metamodeling in particular, may support pragmatic aspects that reflect epistemic and cognitive aspects of scientific investigations. For this, DSLs and language metamodeling in particular are set into the context of "model-based science" and "model-based reasoning". It is shown that the specific properties of metamodel-based DSLs may be used to support those properties, in particular transparency, which are of particular relevance against the background of uncertainty, that is a characterizing property of EMS. The findings are the base for the formulation of an corresponding specific metamodel- based approach for the provision of modeling tools for EMS (Language-centered Approach, LCA), which has been implemented (modeling tool ECA-EMS), including a new DSL for CA modeling for EMS (ECAL). At the base of this implementation, the applicability of this approach is shown