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Similar Scale (similar + scale)
Selected AbstractsScaling and correlation analysis of galactic imagesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2001P. Frick Different scaling and autocorrelation characteristics and their application to astronomical images are discussed: the structure function, the autocorrelation function, Fourier spectra and wavelet spectra. The choice of the mathematical tool is of great importance for the scaling analysis of images. The structure function, for example, cannot resolve scales that are close to the dominating large-scale structures, and can lead to the wrong interpretation that a continuous range of scales with a power law exists. The traditional Fourier technique, applied to real data, gives very spiky spectra, in which the separation of real maxima and high harmonics can be difficult. We recommend as the optimal tool the wavelet spectrum with a suitable choice of the analysing wavelet. We introduce the wavelet cross-correlation function, which enables us to study the correlation between images as a function of scale. The cross-correlation coefficient strongly depends on the scale. The classical cross-correlation coefficient can be misleading if a bright, extended central region or an extended disc exists in the galactic images. An analysis of the scaling and cross-correlation characteristics of nine optical and radio maps of the nearby spiral galaxy NGC 6946 is presented. The wavelet spectra allow us to separate structures on different scales like spiral arms and diffuse extended emission. Only the images of thermal radio emission and H, emission give indications of three-dimensional Kolmogorov-type turbulence on the smallest resolved scales . The cross-correlations between the images of NGC 6946 show strong similarities between the images of total radio emission, red light and mid-infrared dust emission on all scales. The best correlation is found between total radio emission and dust emission. Thermal radio continuum and H, emission are best correlated on a scale of about , the typical width of a spiral arm. On a similar scale, the images of polarized radio and H, emission are anticorrelated, a fact that remains undetected with classical cross-correlation analysis. [source] Evolution and implications of genome rearrangements in ciliatesTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 2 2005LAURA A. KATZ We are exploring genome evolution in diverse ciliates to assess whether patterns of protein evolution correspond to the presence of genome duality, and to levels of genome rearrangements among ciliates. Ciliate genomes contain an estimated 25,000,35,000 genes, a number higher than that of other characterized microbial eukaryotes and on a similar scale to that of humans and Arabidopsis thaliana. We have previously hypothesized that the divergence among ciliate proteins, and the accumulation of paralogs within ciliate taxa, is due to differential selection on the functional macronucleus and the transcriptionally inactive micronucleus. To assess this hypothesis, we are expanding our analyses of protein-coding gene sequences to compare the fate of proteins in ciliates to that of other eukaryotes, and to test whether the most divergent ciliate proteins are found in ciliates with extensively processed genomes. These analyses, combined with a phylogenetic perspective that reveals multiple origins of extensive fragmentation in ciliates, provide a possible explanation for the large genome size and diversity of proteins in ciliates. [source] PHA bioplastic: A value-added coproduct for biomass biorefineriesBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 4 2009Kristi D. Snell Abstract The petroleum industry has optimized profits by producing value-added coproducts, such as plastics and chemicals, in addition to primary liquid fuels. A similar coproduct strategy applied to biorefineries processing cellulosic biomass to liquid fuels and/or energy would transform a technology that is marginally economic, depending on oil prices, to a sustainable business with enhanced revenue streams from multiple coproducts. The challenge is finding a biobased coproduct that is compatible with a biorefinery scenario and where markets warrant its production on a similar scale as liquid fuels and/or energy. Polyhydroxyalkanoate (PHA) bioplastics represent a coproduct that would be entirely compatible with either production of liquid fuels by hydrolyzing the residual biomass after PHA extraction or by alternative thermochemical processes. PHA bioplastics possess properties making them suitable replacements for many of the applications currently served by petroleum-based plastics, thus providing tremendous market potential. Proof-of-concept technology for production of these plastics in several crops of agronomic interest has been demonstrated. In this review, we show that the potential for developing biomass-based biorefineries producing liquid fuels and a value-added coproduct is both real and realizable. Examples using switchgrass producing PHA bioplastics as a coproduct are described. © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd. [source] 122 Local to Coastal-Scale Macrophyte Community Structure: Surprizing Patterns and Possible MechanismsJOURNAL OF PHYCOLOGY, Issue 2003B. A. Menge Understanding large-scale patterns in ecological communities is a central goal of ecology, and yet, rigorous quantitative geographic data on distribution, abundance and diversity are almost totally lacking. Even in rocky intertidal habitats, our data on community structure are spatially and temporally limited, with most surveys limited to a few sites over short time periods. When linked to studies of community dynamics on similar scales, such studies should provide insights into the determinants of pattern at more relevant scales. In 1999 PISCO, the Partnership for Interdisciplinary Studies of Coastal Oceans, initiated survey programs aimed at determining patterns of community structure along the US west coast from Washington to Baja California. Sites are regularly spaced along the coast in a nested design, and were physically similar. Surveys used randomly placed quadrats in transects run parallel to shore in high, mid and low zones. Results show that, contrary to expectation, macroalgal diversity along the northern coast was higher, not lower than that along the southern coast. Possible factors associated with this unexpected pattern include along-coast variation in tidal amplitude, time of tide, thermal stress, upwelling intensity and resulting nutrient gradients, disturbance from storms or sand burial, and grazing. We review evidence relevant to these factors, and focus on the possible role of grazing, using field experiments done under differing oceanographic conditions along the Oregon coast as a model. Although short-term grazing rates can vary with oceanographic condition, we hypothesize that despite these results and those of many similar studies showing strong grazing effects on local spatial and short time scales, that bottom-up factors are stronger determinants of macroalgal community structure on larger spatial scales and longer time scales. [source] | ||||||||||