Parallelizing non-vectorizable loops for MIMD machines

Parallelizing a loop for MIMD machines can be described as a process of partitioning it into a number of relatively independent subloops. Previous approaches to partitioning non-vectorizable loops were mainly based on iteration pipelining which partitioned a loop based on iteration number and exploited parallelism by overlapping the execution of iterations. However, the amount of parallelism exploited this way is limited because the parallelism inside iterations has been ignored. In this paper, we present a new loop partitioning technique which can exploit both forms of parallelism - inside and across iterations. While inspired by the VLIW approach, our method is designed for more general, asynchronous, MIMD machines. In particular, our schedule takes the cost of communication into account, and attempts to balance it with respect to parallelism. We show our method is correct, efficient, and produces better schedules than previous iteration level approaches

N-Dimensional Perfect Pipelining

In this paper, we introduce a technique to parallelize nested loops at the fine grain level. It is a generalization of Perfect Pipelining which was developed to parallelize a single-nested loop at the fine grain level. Previous techniques that can parallelize nested loops, e.g. DOACROSS or Wavefront method, mostly belong to the coarse grain approach. We explain our method, contrast it with the coarse grain techniques, and show the benefits of parallelizing nested loops at the fine grain level

Fine grain software pipelining of non-vectorizable nested loops

This paper presents a new technique to parallelize nested loops at the statement level. It transforms sequential nested loops, either vectorizable or not, into parallel ones. Previously, the wavefront method was used to parallelize non-vectorizable nested loops. However, in order to reduce the complexity of parallelization, the wavefront method regards an iteration as an unbreakable scheduling unit and draws parallelism through iteration overlapping. Our technique takes a statement rather than an iteration as the scheduling unit and exploits parallelism by overlapping the statements in all dimensions. In this paper, we show how this finer grain parallelization can be achieved with reasonable computational complexity, and the effectiveness of the resulting method in exploiting parallelism

Ellipsometric measurement of liquid film thickness

The immediate objective of this research is to measure liquid film thickness from the two equilibrium phases of a monotectic system in order to estimate the film pressure of each phase. Thus liquid film thicknesses on the inside walls of the prism cell above the liquid level have been measured elliposmetrically for the monotectic system of succinonitrile and water. The thickness varies with temperature and composition of each plane. The preliminary results from both layers at 60 deg angle of incidence show nearly uniform thickness from about 21 to 23 C. The thickness increases with temperature but near 30 C the film appears foggy and scatters the laser beam. As the temperature of the cell is raised beyond room temperature it becomes increasingly difficult to equalize the temperature inside and outside the cell. The fogging may also be an indication that solution, not pure water, is adsorbed onto the substrate. Nevertheless, preliminary results suggest that ellipsometric measurement is feasible and necessary to measure more accurately and rapidly the film thickness and to improve thermal control of the prism walls

Fine-grain loop scheduling for MIMD machines

Previous algorithms for parallelizing loops on MIMD machines have been based on assigning one or more loop iterations to each processor, introducing synchronization as required. These methods exploit only iteration level parallelism, and ignore the parallelism that may exist at a lower level.In order to exploit parallelism both within and across iterations, our algorithm analyzes and schedules the loop at the statement level. The loop schedule reflects the expected communication and synchronization costs of the target machine. We provide test results that show that this algorithm can produce good speedup of loops on an MIMD machine

Clockwork graviton contributions to muon g−2g-2

The clockwork mechanism for gravity introduces a tower of massive graviton modes, "clockwork gravitons," with a very compressed mass spectrum, whose interaction strengths are much stronger than that of massless gravitons. In this work, we compute the lowest order contributions of the clockwork gravitons to the anomalous magnetic moment, $g-2$, of muon in the context of extra dimensional model with a five dimensional Planck mass, $M_5$. We find that the total contributions are rather insensitive to the detailed model parameters, and determined mostly by the value of $M_5$. In order to account for the current muon $g-2$ anomaly, $M_5$ should be around $0.2~{\rm TeV}$, and the size of the extra dimension has to be quite large, $l_5 \gtrsim 10^{-7}\,$m. For $M_5\gtrsim1~{\rm TeV}$, the clockwork graviton contributions are too small to explain the current muon $g-2$ anomaly. We also compare the clockwork graviton contributions with other extra dimension models such as Randall-Sundrum models or large extra dimension models. We find that the leading contributions in the small curvature limit are universal, but the cutoff-independent subleading contributions vary for different background geometries and the clockwork geometry gives the smallest subleading contributions.Comment: 14 pages, 4 figures: v3 minor corrections, to appear in PR

Mechanisms of color change and the prevention of off-color and off-flavor in irradiated meat

To determine the effect of irradiation on the oxidative quality changes during the storage, pork loin and turkey breast muscles were irradiated using an electron beam. Irradiation accelerated lipid oxidation, increased redness, and produced several sulfur (S)-volatiles that were responsible for the characteristic irradiation off-odor. This quality deterioration by irradiation was dependent on packaging conditions. Lipid oxidation was more problematic when meat was aerobically stored, whereas the production of S-volatiles was greater in vacuum-packaged irradiated raw meats. But when meat was freezer-stored, aerobic packaging was more susceptible to the production of both oxidation-dependent and S-volatiles. Irradiation made the color of meats redder and the redness was more distinct and stable under vacuum conditions. In irradiated meat, the production of carbon monoxide (CO), which can bind to myoglobin as a sixth ligand, was proportional to the irradiation dose. Oxidation-reduction potential was also decreased by irradiation indicating that more reducing conditions were supplied to heme pigments. Thus, it can be concluded that the increased a*-values in irradiated meat was caused by heme pigment-CO ligand formation. The absorption spectra of meat drip also showed that the peak wavelengths of irradiated meat were similar to those of the CO-myoglobin. Therefore, we suggest that CO-myoglobin be a major heme pigment responsible for the red or pink color in irradiated meats. These color changes and the mechanisms in irradiated raw meat were similar in irradiated precooked meat. A few strategies to reduce the oxidative quality deterioration of irradiated meats were studied. Addition of an antioxidant (sesamol, gallate, Trolox, or alpha-tocopherol) or their combination was effective in reducing the S-volatiles in vacuum-packaged irradiated meats or in controlling lipid oxidation in aerobically packaged irradiated ones. A modified packaging concept (double-packaging; combined use of vacuum and aerobic packaging) was also effective in eliminating S-volatiles and minimizing lipid oxidation during the storage. Especially, gallate + alpha-tocopherol along with double-packaging reduced effectively the red color of irradiated raw and cooked meats. These beneficial effects of double-packaging and antioxidant were more critical in irradiated cooked meat, and it was a very effective method to control the oxidative quality changes of irradiated meats