130,898 research outputs found
Coltivazione in floating system di Lactuca sativa L. (var. Salanova) con soluzione nutritiva a due concentrazioni
No full textLa qualità e la resa delle colture dipendono da fattori ambientali e dalla disponibilità degli elementi nutritive. Nelle coltivazioni idroponiche la concentrazione degli elementi nutritivi nelle soluzioni nutritive dipende dal fabbisogno delle colture e dalla qualità dell’acqua. Laddove la salinità dell’acqua è elevata si deve ridurre la quantità di nutrienti nella soluzione nutritiva. L’obiettivo del lavoro è stato quello di ridurre la concentrazione di macroelementi e valutare la risposta della lattuga in termini di resa e di conservazione postraccolta.
È stato utilizzato un sistema idroponico floating system, composto da 20 vasche con un volume di 40 L ciascuna. Sono state coltivate due varietà di Lactuca sativa L. (var. Salanova), una verde “Expertise” (EXP) e una rossa “Codex” (COD), particolarmente apprezzate dalla IV gamma per forma e conservabilità in post-raccolta. Per la nutrizione minerale, è stata preparata una soluzione Hoagland con dosaggio al 100% per 10 vasche (5 per varietà), e al 50% per le restanti (5 per varietà). Sono stati condotti due cicli, sostituendo per il secondo la soluzione nutritiva inizialmente impiegata. In entrambi i casi, a un mese dalla semina si è proceduto al trapianto in alveoli alloggiati in appositi pannelli in polistirene espanso. Come substrato è stato utilizzato lana di rocca per il primo ciclo e perlite espansa per il secondo, con la funzione di ancoraggio delle radici, oltre che da volano idrico-nutrizionale. La soluzione nutritiva è stata ossigenata regolarmente per mezzo di un compressore ad aria collegato a un impianto di distribuzione. Settimanalmente sono state effettuate analisi morfologiche (altezza e diametro della pianta) per monitorare lo sviluppo della coltura, e multiparametriche (pH, EC, % Ossigeno, Temperatura) della soluzione nutritiva. Sono stati mantenuti pH 5,5-6,5, ossigeno 50-75%, temperatura 22-26°C ed EC, 1,2-1,6 mS/cm per le vasche al 50%, e 2-2,8 mS/cm per quelle al 100%. Una volta che le piante hanno raggiunto mediamente i 20 cm di altezza, si è proceduto alla raccolta, determinando le rese di biomassa fresca per varietà e condizione. Il campionamento e le relative analisi distruttive sono stati effettuati alla raccolta e dopo sei, dieci e dodici giorni di conservazione. Le foglie di lattuga sono state poste in quantità omogenee, 50 g per il primo ciclo e 80 g per il secondo, in confezioni di plastica e conservate in una cella frigorifera a 5 °C. È stata valutato il contenuto di clorofille, carotenoidi, fenoli, antociani, zuccheri totali e nitrati. Non sono state registrate differenze statisticamente significative per i parametri nutraceutici relativi alla qualità, così come per il contenuto di zuccheri (maggiore al 50%), e di nitrati (maggiore al 100%), risultante nettamente inferiore alle soglie di legge sia alla raccolta che durante il processo di conservazione in entrambi i cicli. A sei, dieci e dodici giorni post raccolta sono state pesate le confezioni per determinare eventuali differenze nell’attività respiratoria fogliare e nel mantenimento dei livelli di zucchero nelle foglie. Non si sono evidenziate differenze significative nella resa in biomassa fresca, osservando nel primo ciclo rese maggiori con soluzione nutritiva al 50% (COD = 551,1 g/m2; EXP = 305,82 g/m2), mentre nel secondo al 100% (COD = 1,73 Kg/m2; EXP = 1,82 Kg/m2) per entrambe le varietà. In conclusione, si è potuto osservare come la qualità nutraceutica del prodotto e la resa finale in biomassa fresca non siano variate significativamente per entrambe le varietà nonostante l’impiego di soluzioni nutritive a differente concentrazione minerale
NemaFootPrinter: a web based software for the identification of conserved non-coding genome sequence regions between <it>C. elegans </it>and <it>C. briggsae</it>
No full textAbstract Background NemaFootPrinter (Nematode Transcription Factor Scan Through Philogenetic Footprinting) is a web-based software for interactive identification of conserved, non-exonic DNA segments in the genomes of C. elegans and C. briggsae. It has been implemented according to the following project specifications: a) Automated identification of orthologous gene pairs. b) Interactive selection of the boundaries of the genes to be compared. c) Pairwise sequence comparison with a range of different methods. d) Identification of putative transcription factor binding sites on conserved, non-exonic DNA segments. Results Starting from a C. elegans or C. briggsae gene name or identifier, the software identifies the putative ortholog (if any), based on information derived from public nematode genome annotation databases. The investigator can then retrieve the genome DNA sequences of the two orthologous genes; visualize graphically the genes' intron/exon structure and the surrounding DNA regions; select, through an interactive graphical user interface, subsequences of the two gene regions. Using a bioinformatics toolbox (Blast2seq, Dotmatcher, Ssearch and connection to the rVista database) the investigator is able at the end of the procedure to identify and analyze significant sequences similarities, detecting the presence of transcription factor binding sites corresponding to the conserved segments. The software automatically masks exons. Discussion This software is intended as a practical and intuitive tool for the researchers interested in the identification of non-exonic conserved sequence segments between C. elegans and C. briggsae. These sequences may contain regulatory transcriptional elements since they are conserved between two related, but rapidly evolving genomes. This software also highlights the power of genome annotation databases when they are conceived as an open resource and the possibilities offered by seamless integration of different web services via the http protocol. Availability: the program is freely available at http://bio.ifom-firc.it/NTFootPrinter</p
Towards sustainable hydrogen production: Integrating electrified and convective steam reformer with carbon capture and storage
No full textThis work reports the design of a process for hydrogen production based on electrified steam methane reforming (e-SMR) coupled with a convective reforming (convective SMR) and carbon capture and storage (CCS) as an alternative to conventional fuel-fired reforming to reduce natural gas (NG) consumption as well as carbon dioxide emissions. The energy required by the reforming reaction is supplied by direct electric heating instead of burning fossil fuel in the radiant section of a furnace, saving 35 % NG and reducing CO2 emission by 29 %. Implementing convective SMR reduces the electric load of the main e-SMR reactor and ensures a slightly higher thermal efficiency (80.2 %) compared to conventional fuel-fired reforming (78.9 %). Further CO2 emissions (85 %) and NG consumption reduction (50 %) are possible by adopting amine-based CO2 capture. If coupled with an energy integration scheme, it is possible to capture 75 % of the CO2 produced, preserving high energy efficiency (79.4 %). This requires only a 14 % increase in capital costs, which is strongly beneficial compared to applying CO2 capture to flue gases of the fuel-fired reforming (69.8 % efficiency and 80 % more capital costs). The process based on e-SMR coupled with convective SMR and CO2 capture ensures a levelized cost of hydrogen (LCOH) of 0.281 € Nm−3 H2, which is much lower than the conventional fuel-fired reforming with CO2 capture applied to flue gases (0.309 € Nm−3 H2). Moreover, it has comparable CO2 emissions (1.59 vs 0.99 kg CO2 emitted kg−1 H2) but produces lower CO2 (6.39 vs 9.88 CO2 produced kg−1 H2) compared to fuel-fired reforming due to using renewable electricity as energy source for the SMR. Compared to conventional fuel-fired reforming, the same process provides similar LCOH (0.283 vs 0.282 € Nm−3 H2) but with drastically lower CO2 emissions (1.59 vs 8.99 kg CO2 emitted kg−1 H2)
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Genome-wide microRNA target gene identification and annotation using multiple prediction algorithms
No full textA complex array of miRNAs is deregulated in disease-related hypertrophy of the postnatal heart; reactivation of the fetal microRNA program seems to substantially contribute to alterations of gene expression and translation. The prediction of target genes may represent an approach to study the function of the related miRNAs. Because the structural variability of duplex the approaches currently used identify a subset very small compared to the number of real targets. The purpose of the project consist of build-up a protocol which can generate a pattern of target genes associated with a specific miRNA. We have developed a strategy for scanning a 3'-UTR data set against miRNA, through the use of multiple methods of target prediction. The list of target genes needs to be characterized by association with gene ontology terms and by pathway analysis, in order to allow the assignment of miRNA to well defined functional patterns
A DOCTRINAL VIEW OF LOGIC
No full textThe general framework of this thesis is Categorical Logic, more precisely the one of Doctrines, introduced by Lawvere in 1969. Doctrines are a categorical tool that allows the analysis of both syntax and semantics of logical theories — in particular first-order theories — using the same mathematical structure.
The thesis begins with a thorough analysis of Henkin’s Theorem for first-order logic (“every consistent theory has a model”), with the aim of interpreting it in the language of existential implicational doctrines. The thesis also considers how to describe free constructions in algebra in the context of elementary doctrines.
At first, we study the meaning of “adding a constant to a language” for any doctrine, and “adding an axiom to a theory” for a primary doctrine.
These constructions are used to find a possible interpretation of Henkin’s Theorem. Starting from a consistent doctrine, we construct a new doctrine which is rich, where a theory is rich when for every valid formula of the kind ∃xφ(x) there exists a witness constant c such that φ(c) holds. We then show that a rich doctrine admits an appropriate morphism towards the doctrine of subsets. Henkin’s Theorem for doctrines follows from these two results, and our proof in the context of existential implicational doctrines is modeled on the main lines of the original theorem.
Finally, the thesis proposes a further analysis of the procedure for adding structure and axioms to a theory, this time in the context of elementary doctrines. It is well-known in universal algebra that adding structure and equational axioms generates forgetful functors between varieties, and such functors all have left adjoints. Given a morphism of elementary doctrines, we prove the existence of a left adjoint of the functor induced by precomposition in the doctrine of subobjects of a Grothendieck topos. It is then shown how the existence of free functors in universal algebra follows from a more general result that lives in the theory of doctrines
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Splicy: a web-based tool for the prediction of possible alternative splicing events from Affymetrix probeset data
No full textBACKGROUND: The Affymetrix technology is nowadays a well-established method for the analysis of gene expression profiles in cancer research studies. However, changes in gene expression levels are not the only way to link genes and disease. The existence of gene isoforms specifically linked with cancer or apoptosis is increasingly found in literature. Hence it is of great interest to associate the results of a gene expression study with updated evidences on the transcript structure and its possible variants. RESULTS: We present here a web-based software tool, Splicy, whose primary task is to retrieve data on the mapping of Affymetrix probes to single exons of gene transcripts and displaying graphically this information projected on the gene physical structure.Starting from a list of Affymetrix probesets the program produces a series of graphical displays, each relative to a transcript associated with the gene targeted by a given probe. The information on the transcript-by-transcript and exon-by-exon mapping of probe pairs can be retrieved both graphically and in the form of tab-separated files. The mapping of single probes to NCBI RefSeq or EMBL cDNAs is handled by the ISREC mapping tables used in the CleanEx Expression Reference Database Project. We currently maintain these mappings for most popular human and mouse Affymetrix chips, and Splicy can be queried for matches with human and mouse NCBI RefSeq or EMBL cDNAs. CONCLUSION: Splicy generates probeset annotations and images describing the relation between the single probes and intron/exon structure of the target transcript in all its known variants. We think that Splicy will be useful for giving to the researcher a clearer picture of the possible transcript variants linked with a given gene and an additional view on the interpretation of microarray experiment data. Splicy is publicly available and has been realized in the framework of a bioinformatics grant from the Italian Cancer Research Association.GR-BUCHE
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Unbiased determination of polarized parton distributions and their uncertainties
No full textWe present a determination of a set of polarized parton distributions (PDFs) of the nucleon, at next-to-leading order, from a global set of longitudinally polarized deep-inelastic scattering data: NNPDFpol1.0. The determination is based on the NNPDF methodology: a Monte Carlo approach, with neural networks used as unbiased interpolants, previously applied to the determination of unpolarized parton distributions, and designed to provide a faithful and statistically sound representation of PDF uncertainties. We present our dataset, its statistical features, and its Monte Carlo representation. We summarize the technique used to solve the polarized evolution equations and its benchmarking, and the method used to compute physical observables. We review the NNPDF methodology for parametrization and fitting of neural networks, the algorithm used to determine the optimal fit, and its adaptation to the polarized case. We finally present our set of polarized parton distributions. We discuss its statistical properties, test for its stability upon various modifications of the fitting procedure, and compare it to other recent polarized parton sets, and in particular obtain predictions for polarized first moments of PDFs based on it. We find that the uncertainties on the gluon, and to a lesser extent the strange PDF, were substantially underestimated in previous determinations. © 2013 Elsevier B.V
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