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Procedural shaders are a vital part of modern rendering systems. Despite their prevalence, however, procedural shaders remain sensitive to aliasing any time they are sampled at a rate below the Nyquist limit. Antialiasing is typically achieved through numerical techniques like supersampling or precomputing integrals stored in mipmaps. This paper explores the problem of analytically computing a band-limited version of a procedural shader as a continuous function of the sampling rate. There is currently no known way of analytically computing these integrals in general. We explore the conditions under which exact solutions are possible and develop several approximation strategies for when they are not. Compared to supersampling methods, our approach produces shaders that are less expensive to evaluate and closer to ground truth in many cases. Compared to mipmapping or precomputation, our approach produces shaders that support an arbitrary bandwidth parameter and require less storage. We evaluate our method on a range of spatially-varying shader functions, automatically producing antialiased versions that have comparable error to 4x4 multisampling but can be over an order of magnitude faster. While not complete, our approach is a promising first step toward this challenging goal and indicates a number of interesting directions for future work.

Modern compilers typically optimize for executable size and speed, rarely exploring non-functional properties such as power efficiency. These properties are often hardwarespecific, time-intensive to optimize, and may not be amenable to standard dataflow optimizations. We present a general post-compilation approach called Genetic Optimization Algorithm (GOA), which targets measurable non-functional aspects of software execution in programs that compile to x86 assembly. GOA combines insights from profile-guided optimization, superoptimization, evolutionary computation and mutational robustness. GOA searches for program variants that retain required functional behavior while improving non-functional behavior, using characteristic workloads and predictive modeling to guide the search. The resulting optimizations are validated using physical performance measurements and a larger held-out test suite. Our experimental results on PARSEC benchmark programs show average energy reductions of 20%, both for a large AMD system and a small Intel system, while maintaining program functionality on target workloads.

One limitation of employing lux bioreporters to monitor in situ microbial gene expression in dynamic, laboratory-scale systems is the confounding variability in the luminescent responses. For example, despite careful control of oxygen tension, growth stage, and cell number, luminescence from Pseudomonas putida RB1353, a naphthalene-degrading lux bioreporter, varied by more than sevenfold during saturated flow column experiments in our laboratory. Therefore, this study was conducted to determine what additional factors influence the luminescent response. Specifically, this study investigated the impact of temperature, pH, and initial cell number (variations within an order of magnitude) on the peak luminescence of P. putida RB1353 and the maximum degradation rate (V max ) during salicylate and naphthalene catabolism. Statistical analyses based on general linear models indicated that under constant oxygen tension, temperature and pH accounted for 98.1% of the variability in luminescence during salicylate catabolism and 94.2 and 49.5% of the variability in V max during salicylate and naphthalene catabolism, respectively. Temperature, pH, and initial substrate concentration accounted for 99.9% of the variability in luminescence during naphthalene catabolism. Initial cell number, within an order of magnitude, did not have a significant influence on either peak luminescence or V max during salicylate and naphthalene catabolism. Over the ranges of temperature and pH evaluated, peak luminescence varied by more than 4 orders of magnitude. The minimum parameter deviation required to alter lux gene expression during salicylate and naphthalene catabolism was a change in temperature of 1°C, a change in pH of 0.2, or a change in initial cell number of 1 order of magnitude. Results from this study indicate that there is a need for careful characterization of the impact of environmental conditions on both the expression of the reporter and catabolic genes and the activities of the gene products. For example, even though lux gene expression was occurring at ϳ35°C, the luciferase enzyme was inactive. Furthermore, this study demonstrates that with careful characterization and standardization of measurement conditions, the attainment of a reproducible luminescent response and an understanding of the response are feasible.One of the major constraints on implementing in situ bioremediation is the lack of understanding of how physical, biological, and chemical factors affect microbial activity (7). In an attempt to understand how these factors impact bioremediation, reporter organisms have been developed that allow monitoring of microbial interaction with organic compounds in dynamic systems (6,20). Reporter organisms are genetically engineered organisms in which a reporter gene(s), such as lux, luc, or gfp, that encodes a detectable gene product is under regulatory control of an inducible catabolic operon (12). In general, due to a relatively short half-life, luciferase (lux or luc) is preferable in applications where dynamic measure...

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