3,661 research outputs found

    Generation and validation of spatial distribution of hourly wind speed time-series using machine learning

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    Wind resource assessment is a key aspect of wind farm planning since it allows to estimate the long term electricity production. Moreover, wind speed time -series at high resolution are helpful to estimate the temporal changes of the electricity generation and indispensable to design stand-alone systems, which are affected by the mismatch of supply and demand. In this work, we present a new generalized statistical methodology to generate the spatial distribution of wind speed time-series, using Switzerland as a case study. This research is based upon a machine learning model and demonstrates that statistical wind resource assessment can successfully be used for estimating wind speed time-series. In fact, this method is able to obtain reliable wind speed estimates and propagate all the sources of uncertainty (from the measurements to the mapping process) in an efficient way, i.e. minimizing computational time and load. This allows not only an accurate estimation, but the creation of precise confidence intervals to map the stochasticity of the wind resource for a particular site. The validation shows that machine learning can minimize the bias of the wind speed hourly estimates. Moreover, for each mapped location this method delivers not only the mean wind speed, but also its confidence interval, which are crucial data for planners

    Selection for Self-Fertility and Self-Fertility in Alfalfa as a Tool for Breeding Strategy Assessment

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    Cultivar development in alfalfa relies on heterosis, that has been mainly exploited by intercrossing selected clones from diverse gemplasm sources; an alternative way was proposed, based on developing double cross cultivars obtained by crossing clones selected for self-sterility, propagated by somatic seed. A different breeding strategy was recently emphasized based on population improvement through inbreeding and recurrent selection; in this case, self-sterility would be selected against. If self-sterility is determined by genetic load, the second strategy should be preferred, and selecting for self-fertility may bring about positive correlated responses for forage yield. Divergent selection for self-fertility was applied in a central Italian alfalfa landrace to test this hypothesis. Ten self-fertile and ten self-sterile plants were selected and hand-crossed without emasculation in a n(n-1) diallel; seeds of reciprocal crosses were pooled, obtaining 45 full-sib families per fertility group. Ten plants per family were evaluated for self-fertility. Selection was effective for self-fertility (h2 R=0.52), but not for self-sterility, a result expected if self-sterility is determined by genetic load. The forage yield of self-fertile progenies was 135% of the unselected control and 123% of the self-sterile progenies in a dense stand trial (first cut, seedling year), indicating that selection for self-fertility could be a tool for population improvement

    Ab initio analysis of the x-ray absorption spectrum of the myoglobin-carbon monoxide complex: Structure and vibrations

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    We present a comparison between Fe K-edge x-ray absorption spectra of carbonmonoxy-myoglobin and its simulation based on density-functional theory determination of the structure and vibrations and spectral simulation with multiple-scattering theory. An excellent comparison is obtained for the main part of the molecular structure without any structural fitting parameters. The geometry of the CO ligand is reliably determined using a synergic approach to data analysis. The methodology underlying this approach is expected to be especially useful in similar situations in which high-resolution data for structure and vibrations are available.Comment: 13 pages, 3 figure

    Phylogenetic clustering of wingbeat frequency and flight-associated morphometrics across insect orders

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    Wingbeat frequency in insects is an important variable in aerodynamic and energetic analyses of insect flight and often is studied on a family‐ or species‐level basis. Meta‐analyses of these studies report order‐level patterns suggesting that flight strategy is moderately well conserved phylogenetically. Studies incorporated into these meta‐analyses, however, use variable methodologies across different temperatures, which may confound results and phylogenetic patterns. In the present study, a high‐speed camera is used to measure wingbeat frequency in a wide variety of species (n = 102) under controlled conditions aiming (i) to determine the validity of previous meta‐analyses showing phylogenetic clustering of flight strategy and (ii) to identify new evolutionary patterns between wingbeat frequency, body mass, wing area, wing length and wing loading at the order level. All flight‐associated morphometrics significantly affect wingbeat frequency. Linear models show that wing area explains the most amount of variation in wingbeat frequency (r2 = 0.59, P ≀ 0.001), whereas body mass explains the least (r2 = 0.09, P ≀ 0.01). A multiple regression model incorporating both body mass and wing area is the best overall predictor of wingbeat frequency (r2 = 0.84, P ≀ 0.001). Order‐level phylogenetic patterns across relationships are consistent with previous studies. Thus, the present study provides experimental validation of previous meta‐analyses and provides new insights into phylogenetically conserved flight strategies across insect orders

    A Molecular Study of Alfalfa Megasporogenesis

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    Our ability to control plant reproduction impacts on both seed production and plant breeding. A female sterility mutation was previously described (Rosellini et al., 1998; 2003) revealing a female-specific arrest of sporogenesis associated with ectopic, massive callose deposition within the nucellus. The goal of this study is to isolate and characterize genes involved in megasporogenesis and female sterility in alfalfa

    Circulating microRNAs: next-generation biomarkers for early lung cancer detection

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    Early diagnosis of lung cancer by low-dose computed tomography is an effective strategy to reduce cancer mortality in high-risk individuals. However, recruitment of at-risk individuals with asymptomatic lung cancer still remains challenging. We developed a minimal invasive serum test, based on the detection of circulating microRNAs, which can identify at-risk individuals with asymptomatic early stage non-small cell lung carcinomas with 80% accuracy

    The n-acetyl phenylalanine glucosamine derivative attenuates the inflammatory/catabolic environment in a chondrocyte-synoviocyte co-culture system

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    Osteoarthritis (OA), the most prevalent degenerative joint disease, still lacks a true disease-modifying therapy. The involvement of the NF-ÎșB pathway and its upstream activating kinases in OA pathogenesis has been recognized for many years. The ability of the N-acetyl phenylalanine glucosamine derivative (NAPA) to increase anabolism and reduce catabolism via inhibition of IKKα kinase has been previously observed in vitro and in vivo. The present study aims to confirm the chondroprotective effects of NAPA in an in vitro model of joint OA established with primary cells, respecting both the crosstalk between chondrocytes and synoviocytes and their phenotypes. This model satisfactorily reproduces some features of the previously investigated DMM model, such as the prominent induction of ADAMTS-5 upon inflammatory stimulation. Both gene and protein expression analysis indicated the ability of NAPA to counteract key cartilage catabolic enzymes (ADAMTS-5) and effectors (MCP-1). Molecular analysis showed the ability of NAPA to reduce IKKα nuclear translocation and H3Ser10 phosphorylation, thus inhibiting IKKα transactivation of NF-ÎșB signalling, a pivotal step in the NF-ÎșB-dependent gene expression of some of its targets. In conclusion, our data confirm that NAPA could truly act as a disease-modifying drug in OA

    Genetic Variability of Lucerne Landraces from Central Italy Detected by RAPD Markers

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    With the aim to characterize six lucerne landraces (Medicago sativa L.), representing a sample of a collection from central Italy, sixty individuals per landrace were evaluated by screening for RAPD markers with three lucerne-specific primers. Twenty-one amplification products were scored as present or absent across all plants. The dendrogram from mean genetic similarity estimates displayed Casalina alone and the other landraces clustered into one distinct group, showing a single branch point with more than 73% of genetic similarity. The discriminant analysis grouped the landraces in a similar manner. The first function maximally separated the group Grosseto, Gubbio and C. Pieve from Latina and L’Aquila while the second function maximally separated Casalina from the rest of landraces. Overall 56% of individual plants were correctly reclassified into their own groups. Owing to their rather narrow geographic provenance, more primers are needed to increase precision in the estimate of the genetic variability

    Variation of DNA methylation and phenotypic traits following unilateral sexual polyploidization in Medicago

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    Sexual hybridization is an important generator of biodiversity and a powerful breeding tool. Hybridization can also overcome ploidy barriers when it involves 2n gametes, as in the case of unilateral sexual polyploidization (USP) that has been utilized in several crops, among which alfalfa. This research was aimed at gaining insights into the effects of USP on genome methylation and on phenotypic traits in alfalfa, an important forage species. The Methylation-Sensi- tive Amplified Polymorphism technique was used to estimate the cytosine methylation changes occurring in a tetraploid (2n = 4x = 32) USP progeny from crosses between a diploid Medicago sativa subsp. falcata genotype that produces 2n eggs and a cultivated tetraploid Medicago sativa subsp. sativa variety. De novo methylation or demethylation in the USP progeny were observed for 13% of the detected genomic sites, indicating that methylation changes can be relevant. USP plants showed larger surface area of the leaf epidermis cells than both parents, but this did not result in larger leaf size or higher plant biomass. They displayed significant higher ovule sterility than the tetraploid parent, but normal fertility was observed in crosses with unrelated male testers. We conclude that hybridization and sexual polyploidization resulted in novel variation in terms of remodeling of the methylation landscape as well as changes in phenotypic traits in alfalfa

    A novel microwave and induction heating applicator for metal making: Design and testing

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    The use of microwave heating in primary metallurgy is gaining an increasing interest due to the possibility to selectively process ores and to volumetrically heat large amounts of low-thermal conductivity minerals. In this paper the study, development and testing of a new applicator combining the use of microwave and induction heating for rapid reduction of metal containing oxides is described. Numerical simulation was used in order to achieve the proper control over heat generation, considering the use of microwave solid state generators. A prototype, with a capacity up to 5 liters of standard input feed but with the predisposition for continuous processing has been designed, built and tested on reference loads like iron oxide powders and pellets. Results on the microwave heating part of the applicator indicate that it allows to efficiently and rapidly process these kinds of loads, which change from dielectric to conductors as reduction proceeds. The use of variable frequency solid state microwave generators allows to maximize energy efficiency and to controllably change the heating pattern inside the load
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