Broadband acoustic invisibility and illusions

Rendering objects invisible to impinging acoustic waves (cloaking) and creating acoustic illusions (holography) has been attempted using active and passive approaches. While most passive methods are inflexible and applicable only to narrow frequency bands, active approaches attempt to respond dynamically, interfering with broadband incident or scattered wavefields by emitting secondary waves. Without prior knowledge of the primary wavefield, the signals for the secondary sources need to be estimated and adapted in real time. This has thus far impeded active cloaking and holography for broadband wavefields. We present experimental results of active acoustic cloaking and holography without prior knowledge of the wavefield so that objects remain invisible and illusions intact even for broadband moving sources. This opens previously inaccessible research directions and facilitates practical applications including architectural acoustics, education, and stealth

Out of the rivers: are some aquatic hyphomycetes plant endophytes?

Ingoldian fungi, or aquatic hyphomycetes, are asexual microfungi, mostly ascomycetes, commonly occurring in running freshwater. They grow on dead plant material, such as leaves and twigs, and play a major role in nutrient flows in stream ecosystems (Bärlocher, 1992). They were discovered and first extensively studied by Ingold (1942) and were thus named "Ingoldian" fungi. Ingold described their abundant multicellular asexual spores of sigmoid or, more typically, tetraradiate shape (Fig. 1). He recognized that they probably arose from multiple convergent evolutions, by secondary adaptation to aquatic life, as recently confirmed by molecular markers (Belliveau & Bärlocher, 2005; Baschien et al., 2006). Because of their apparent lack of sexuality, Ingoldian species were placed in asexual genera, such as Tricladium or Tetracladium, based on conidial morphology and/or mode of conidiogenesis. Unexpectedly, several lines of evidence now suggest that some Ingoldian fungi are also plant endophytes, that is, they grow in plants without producing symptoms.[...

Whole genome sequencing of Saccharomyces cerevisiae: from genotype to phenotype for improved metabolic engineering applications

<p>Abstract</p> <p>Background</p> <p>The need for rapid and efficient microbial cell factory design and construction are possible through the enabling technology, metabolic engineering, which is now being facilitated by systems biology approaches. Metabolic engineering is often complimented by directed evolution, where selective pressure is applied to a partially genetically engineered strain to confer a desirable phenotype. The exact genetic modification or resulting genotype that leads to the improved phenotype is often not identified or understood to enable further metabolic engineering.</p> <p>Results</p> <p>In this work we performed whole genome high-throughput sequencing and annotation can be used to identify single nucleotide polymorphisms (SNPs) between <it>Saccharomyces cerevisiae </it>strains S288c and CEN.PK113-7D. The yeast strain S288c was the first eukaryote sequenced, serving as the reference genome for the <it>Saccharomyces </it>Genome Database, while CEN.PK113-7D is a preferred laboratory strain for industrial biotechnology research. A total of 13,787 high-quality SNPs were detected between both strains (reference strain: S288c). Considering only metabolic genes (782 of 5,596 annotated genes), a total of 219 metabolism specific SNPs are distributed across 158 metabolic genes, with 85 of the SNPs being nonsynonymous (e.g., encoding amino acid modifications). Amongst metabolic SNPs detected, there was pathway enrichment in the galactose uptake pathway (<it>GAL1</it>, <it>GAL10</it>) and ergosterol biosynthetic pathway (<it>ERG8</it>, <it>ERG9</it>). Physiological characterization confirmed a strong deficiency in galactose uptake and metabolism in S288c compared to CEN.PK113-7D, and similarly, ergosterol content in CEN.PK113-7D was significantly higher in both glucose and galactose supplemented cultivations compared to S288c. Furthermore, DNA microarray profiling of S288c and CEN.PK113-7D in both glucose and galactose batch cultures did not provide a clear hypothesis for major phenotypes observed, suggesting that genotype to phenotype correlations are manifested post-transcriptionally or post-translationally either through protein concentration and/or function.</p> <p>Conclusions</p> <p>With an intensifying need for microbial cell factories that produce a wide array of target compounds, whole genome high-throughput sequencing and annotation for SNP detection can aid in better reducing and defining the metabolic landscape. This work demonstrates direct correlations between genotype and phenotype that provides clear and high-probability of success metabolic engineering targets. The genome sequence, annotation, and a SNP viewer of CEN.PK113-7D are deposited at <url>http://www.sysbio.se/cenpk</url>.</p

Structural studies of some synthetic zeolites

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Seasonal and yearly changes in consumption of hypogeous fungi by northern flying squirrels and red squirrels in old-growth forest, New Brunswick

Seasonal consumption of mycorrhizal fungus by northern flying squirrels ('Glaucomys sabrinus') and red squirrels ('Tamiasciurus hudsonicus') was examined in old-growth mixedwood forest at Fundy National Park in southern New Brunswick between May 1999 and March 2001. Using faecal pellet analysis, we found that the amount of fungus in the diet of both species was dependent on season and year of study and ranged from 35% to 95%. Twenty fungal taxa, most of them hypogeous Ascomycetes and Basidiomycetes, were detected in diets. More taxa were detected in summer diets compared with all other seasons, but all seasonal samples contained several hypogeous taxa. Up to six taxa were identified in any one sample. Both squirrel species occurred at high densities throughout the study, and dietary overlap between them was great throughout this time in terms of both the amount of fungus and the proportions of different taxa that were consumed. Overall, our data suggest that both 'G. sabrinus' and 'T. hudsonicus' are abundant and important consumers of fungus in the region and that fungus may represent a key food resource, particularly during times when other foods are limited

Processing of 'Eucalyptus viminalis' leaves in Australian streams - importance of aquatic hyphomycetes and zoosporic fungi

The decomposition of 'Eucalyptus viminalis' leaves was examined over 8 weeks in 3 streams, each with two sites, in New South Wales, Australia. Invertebrate colonization of litter bags was negligible. Recovered leaves were aerated to induce sporulation by aquatic hyphomycetes. Conidial numbers generally started to increase after 28 days of stream exposure. Aerated leaves also released round structures tentatively identified as zoosporic propagules. Maxima were reached after 7 days of stream exposure. High levels of ergosterol were found in leaves after 7 days of stream exposure. Exponential decay rates varied between 0.0030 and 0.0065 (day⁻¹) and 0.00018 and 0.00054 (degree day⁻¹). Mass loss rates correlated significantly with maximum conidium release, but not with maximum ergosterol levels or maximum zoospore release, measured physicochemical stream parameters, or the presence of riparian vegetation. As reported from Europe and North-America, aquatic hyphomycetes appeared to play a major role in decomposition, but zoosporic fungi, generally ignored, may be involved in early stages of decay