937 research outputs found
PCR primers based on different portions of insertion elements can assist phylogeny studies, strain fingerprinting and species identification in rhizobia.
No full textUsing the sequence of an insertion element originally found in Rhizobium sullae, the nitrogen-fixing bacterial symbiont of the legume Hedysarum coronarium, we devised three primer pairs (inbound, outbound and internal primers) for the following applications: (a) tracing genetic relatedness within rhizobia using a method independent of ribosomal inheritance, based on the presence and conservation of IS elements; (b) achieve sensitive and reproducible bacterial fingerprinting; (c) enable a fast and unambiguous detection of rhizobia at the species level. In terms of taxonomy, while in line with part of the 16S rRNA gene- and glutamine synthetase I-based clustering, the tools appeared nonetheless more coherent with the actual geographical ranges of origin of rhizobial species, strengthening the European-Mediterranean connections and discerning them from the asian and american taxa. The fingerprinting performance of the outward-pointing primers, designed upon the inverted repeats, was shown to be at least as sensitive as BOX PCR, and to be functional on a universal basis with all 13 bacterial species tested. The primers designed on the internal part of the transposase gene instead proved highly species-specific for R. sullae, enabling selective distinction from its most related species, and testing positive on every R. sullae strain examined, fulfilling the need of PCR-mediated species identification. A general use of other IS elements for a combined approach to rhizobial taxonomy and ecology is proposed
Fertimetro, a Principle and Device to Measure Soil Nutrient Availability for Plants by Microbial Degradation Rates on Differently-Spiked Buried Threads
No full textA novel patented method (PCT/IB2012/001157: Squartini, Concheri, Tiozzo, University of Padova) and the corresponding application devices, suitable to measure soil fertility, are presented. The availability or deficiency of specific nutrients for crops is assessed by monitoring the kinetics of progressive weakening of cotton or silk threads due to in situ microbial activity. The method is based on a nutrient-primed incremented substrate degradation principle. Threads are buried as is or pre-impregnated with N or P solutions, and the acceleration of the degradation rate for the N-supplemented or P-supplemented thread, in comparison to the untreated thread, is proportional to the lack of the corresponding nutrient in that soil. Tests were validated on corn crops in plots receiving increasing fertilizer rates in a historical rotation that has been established since 1962. The measurement carried out in May significantly correlated with the subsequent crop yields recorded in October. The analysis allows an early, inexpensive, fast, and reproducible self-assessment at field level to improve fertilization rates. The device is envisaged as a user-friendly tool for agronomy, horticulture, and any environmental applications where organic matter cycling, soil quality, and specific nutrients excess or deficiency are critical considerations
Intermittent aeration of landfill simulation bioreactors: Effects on emissions and microbial community
No full textLandfill simulation experiments were run at lab-scale to compare the effects of intermittent and continuous aeration on the evolution of leachate composition and biogas production. The experiments were carried out using six reactors; two of them under continuous aeration, two under intermitted aeration and two anaerobic as a control. Different aeration regimes produced different effects on reactors. As expected, carbon discharge via biogas was higher in reactors under continuous aeration than under intermittent aeration. The evolution of leachate quality was affected by the aeration regimes; however, at test end very similar concentration were ascertained for relevant leachate parameters in all aerated reactors. A comprehensive description of the aerobic and anaerobic landfill microbiome is provided, using a metagenomic approach focused on the microbial genome reconstruction. A time course investigation evidenced the modification of the microbiome and revealed taxa and specific microbes more strictly connected to the environmental parameters of the reactors. Methanoculleus, Syntrophomonas and Parabacteroides were identified as the genera more strictly connected to biogas production, while numerous species belonging to Thiomonas, Nitrosomonas, Xanthomonadaceae, Myxococcales and Alcaligenaceae were found to be connected with NH4+ oxidation
Atherosclerosis detection by ultrasounds. A comparative histologic study on aortic specimens
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Molecular properties of a fermented manure preparation used as field spray in biodynamic agriculture
No full textManure products fermented underground in cow horns and commonly used as field spray (preparation 500) in the biodynamic farming system, were characterized for molecular composition by solid-state nuclear magnetic resonance [13 C cross-polarization magic-angle-spinning NMR (13 C-CPMAS-NMR)] spectroscopy and offline tetramethylammonium hydroxide thermochemolysis gas chromatography-mass spectrometry. Both thermochemolysis and NMR spectroscopy revealed a complex molecular structure, with lignin aromatic derivatives, polysaccharides, and alkyl compounds as the predominant components. CPMAS-NMR spectra of biodynamic preparations showed a carbon distribution with an overall low hydrophobic character and significant contribution of lignocellulosic derivatives. The results of thermochemolysis confirmed the characteristic highlighted by NMR spectroscopy, revealing a molecular composition based on alkyl components of plant and microbial origin and the stable incorporation of lignin derivatives. The presence of biolabile components and of undecomposed lignin compounds in the preparation 500 should be accounted to its particularly slow maturation process, as compared to common composting procedures. Our results provide, for the first time, a scientific characterization of an essential product in biodynamic agriculture, and show that biodynamic products appear to be enriched of biolabile components and, therefore, potentially conducive to plant growth stimulation
Environmental Robust Speech and Speaker Recognition through Multi-channel Histogram Equalization
No full textFeature statistics normalization in the cepstral domain is one of the most performing approaches for robust automaticspeech and speaker recognition in noisy acoustic scenarios: feature coefficients are normalized by using suitable linear or nonlinear transformations in order to match the noisy speech statistics to the clean speech one. Histogram equalization (HEQ) belongs to such a category of algorithms and has proved to be effective on purpose and therefore taken here as reference.
In this paper the presence of multi-channel acoustic channels is used to enhance the statistics modeling capabilities of the HEQ algorithm, by exploiting the availability of multiple noisy speech occurrences, with the aim of maximizing the effectiveness of the cepstra normalization process. Computer simulations based on the Aurora 2 database in speech and speaker recognition scenarios have shown that a significant recognition improvement with respect to the single-channel counterpart and other multi-channel techniques can be achieved confirming the effectiveness of the idea. The proposed algorithmic configuration has also been combined with the kernel estimation technique in order to further improve the speech recognition performances
Enhanced network reconstruction from irreducible local information
No full textNetwork topology plays a key role in many phenomena, from the spreading of diseases to that of financial crises. Whenever the whole structure of a network is unknown, one must resort to reconstruction methods that identify the least biased ensemble of networks consistent with the partial information available. A challenging case is when there is only local (node-specic) information available. For binary networks, the relevant ensemble is one where the degree (number of links) of each node is constrained to its observed value. However, for weighted networks the problem is much more complicated. While the naive approach prescribes to constrain the strengths (total link weights) of all nodes, recent counter-intuitive results suggest that in weighted networks the degrees are often more informative than the strengths, and as 'fundamental' as the latter. This implies that the reconstruction of weighted networks would be signicantly enhanced by the specication of both quantities, a computationally hard and bias-prone procedure. Here we solve this problem by introducing an analytical and unbiased maximum-entropy method that works in the shortest possible time and does not require the explicit generation of reconstructed samples. We consider several real-world applications and show that, while the strengths alone give poor results, the additional knowledge of the degrees yields accurately reconstructed networks. Information-theoretic criteria rigorously conrm that the binary information is irreducible to the weighted one. Our results have strong implications for the analysis of motifs and communities and whenever the reconstructed ensemble is required as a null model to detect higher-order patterns
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