Control design for suppressing transversal patterns in reaction–(convection)–diffusion systems

The stabilization of planar stationary fronts solutions in a two-dimensional rectangular or cylinder domain, in which a diffusion–convection–reaction process occurs, is studied by reducing the original two-variable PDEs model to an approximate one-dimensional model that describes the behavior of the front line. We consider the control strategy based on sensors placed at the designed front line position and actuators that are spatially-uniform or space dependent. We present a systematic control design that determines the number of required sensors and actuators, their position and their form. The control used linear analysis of a lumped truncated model and concepts of finite and infinite zeros of linear multidimensional systems.     

New methodology for combined Simulation of delta-I noise interaction with interconnect noise for wide, on-chip data-buses using lossy transmission-line power-blocks

A new technique is described for reducing computational complexity and improving accuracy of combined power distribution and interconnect noise prediction for wide, on-chip data-buses. The methodology uses lossy transmission-line power-blocks with frequency-dependent properties needed for the multigigahertz clock frequencies. The interaction between delta-I noise, common-mode noise, and crosstalk and their effect on timing is illustrated with simulations using representative driver and receiver circuits and on-chip interconnections.     

A five year study. Fluoride release of four reinforced composite resins

PURPOSE: The purpose of this study was to record the fluoride released measured in parts per million of four fluoride composite resins for five years. MATERIALS AND METHODS: Four fluoridated composites were separated into four groups. Two composite resins with high viscosity were core materials, Ti-Core with titanium (group 1) and Ti-Core Natural (group 2) and the other two resins studied were low viscosity post cements Flexi-Flow cement with titanium (group 3) and Flexi-Flow Natural (group 4). The fluoride release was studied under four experimental conditions. Three replications were studied in each condition. Fluoride release was measured for 260 weeks (5 years). STATISTICAL METHODS: A one-way analysis of variance (ANOVA) was used to compare the average weekly release followed by a Student-Newman-Keuls (SNK) pairwise multiple comparison test. All results were considered statistically significant if p < 0.05. RESULTS: The ANOVA analysis released a significant statistical interaction between group and week (p < 0.0001). Further analysis showed that the average weekly release for Ti-Core with titanium did not differ from Ti-Core Natural, and that Ti-Core with titanium and Ti-Core Natural differed from both Flexi-Flow Natural and Flexi-Flow with titanium, which were not different from one another. CONCLUSIONS: Ti-Core with titanium (Group 1) and Ti-Core Natural (Group 2) released a greater amount of fluoride than Flexi-Flow with titanium (Group 3) and Flexi-Flow Natural (Group 4). The fluoride released from these fluoridated resin composites are similar to reported ranges of other fluoride releasing dental restoration materials.     

Correlates of employee lateness: Some theoretical considerations.

Using hypothesis-driven meta-analytic procedures on 30 samples containing 118 correlations, researchers examined competing models of the relationship between lateness and assorted work-related variables. Consistent with a progression withdrawal model, the mean corrected lateness-absence correlation, .40, was found to be higher than the lateness-turnover correlation, .27. Hypotheses regarding the relationships between lateness and attitudes, performance, and demographics were generally supported. Methodological issues, including the need for longitudinal designs in the field and the inclusion of other moderators such as organizational and personality variables, were discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unaltered cosmic spherules in a 1.4-Gyr-old sandstone from Finland

Micrometeorites-submillimetre-sized particles derived from asteroids and comets-occur in significant quantities in deep sea sediments, and the ice sheets of Greenland and Antarctica. The most abundant micrometeorites are cosmic spherules, which contain nickel-rich spinels that were crystallized and oxidized during atmospheric entry, therefore recording the oxygen content in the uppermost atmosphere. But the use of micrometeorites for detecting past changes in the flux of incoming extraterrestrial matter, and as probes of the evolution of the atmosphere, has been hampered by the fact that most objects with depositional ages higher than 0.5 Myr show severe chemical alteration. Here we report the discovery of unaltered cosmic spherules in a 1.4-Gyr-old sandstone (red bed) from Finland. From this we infer that red beds, a common lithology in the Earth's history, may contain substantial unbiased populations of fossil micrometeorites. The study of such populations would allow systematic research on variations in the micrometeorite flux from the early Proterozoic era to recent times (a time span of about 2.5 Gyr), and could help to better constrain the time when the atmospheric oxygen content was raised to its present level.     

A note on lossless database decompositions

It is known that under a wide variety of assumptions a database decomposition is lossless if and only if the database scheme has a lossless join. Biskup, Dayal and Bernstein (1979) have shown that when the given dependencies are functional, the database scheme has a lossless join if and only if one of the relation schemes is a key for the universal scheme. In this note we supply an alternative proof of that characterization. The proof uses tools from the theory of embedded join dependencies and the theory of tuple and equality generating dependencies, but is, nevertheless, much simpler than the previously published proof.