1,721,243 research outputs found
Applicazione e valutazione di sistemi per la sanificazione in ambienti indoor a ridotto impatto ambientale
No full textThe present thesis aimed to evaluate the efficacy of devices, with reduced environmental impact, for biological sanitization of air and surfaces in indoor environments, gave rise to new evidence about the use of UV-C technology. The sanitizing efficacy of two UV-C LED devices was investigated. The first tested system, CSA System S14000, was installed in a university sports pressostatic structure. The sanitization efficacy of the device (which sanitizes up to 19000 m3/h of air) in its entire configuration, and of each single component was assessed following the procedures reported by the ISO 15714:2019. Second, the sanitization efficiency of the device was evaluated through on-site environmental tests in presence of athletes. The results showed high efficacy in eliminating airborne microorganisms, both during efficacy tests (inactivation rate around 99.92 ± 0.07%, log reduction of 3.22 ± 0.39) and in on-site environmental tests (inactivation rate around 70.7 ± 3.6% and 72.4 ± 3.3% for airborne bacteria and molds, respectively). The CSA System S14000 is a promising solution to guarantee efficient and healthy sanitation for athletes during sporting activity. Furthermore, the efficacy of a UV-C LED hand lamp, designed for surface disinfection in domestic or small-scale food-processing environments, was evaluated through in vitro decontamination tests using standard ATCC microorganisms, with different UV-C susceptibility (E. coli ATCC 25922, B. subtilis ATCC 6633, Cladosporium spp.). A bacterial titer 3 logs was achieved with all other microorganisms. Lastly, the ability of UV-C irradiation to induce a VBNC state in E. coli was investigated. The positivity of UV-treated culture-negative samples to enzymatic and resuscitation tests would indicate the possible presence of VBNC cells
Conformational changes in the adenine riboswitch
Full text linkRiboswitches are cis-acting genetic control elements that have been found in the un- traslated region of some mRNAs in bacteria and plants. Riboswitches are known to regulate the genetic expression by means of conformational changes triggered by highly specific interactions of the aptamer with the sensed metabolite. The non-coding sequence in the mRNA of add gene from V. vulnificus contains an adenine responsive riboswitch. Classical molecular dynamics simulations of its aptamer have been performed, both in presence and absence of its physiological ligand starting from the experimental crystal structure. We first use steered MD to induce the opening of the P1 stem and investigate its stability. Our results show that the ligand directly stabilizes the P1 stem by means of stacking interactions quantitatively consistent with thermodynamic data. Then, using both umbrella sampling and a combination of metadynamics and hamiltonian replica exchange, we show that the formation of L2-L3 kissing complex cooperates with ligand binding and we quantify the ligand-induced stabilization. In this context also the influ- ence given by either the monovalent cations or divalent cations was evaluated. Confor- mational changes at pairings detailed level are characterized using a recently introduced technique that is able to distinguish and classify each interaction (i.e. Watson-Crick base pair, non-canonical bp, stacking). Results are compatible with known experimental measurements and shed a new light on the ligand-dependent folding mechanism of the adenine riboswitch
Yeast expression of the Tuber borchii fruiting body specific protein, TBF-1: identification of a noncanonical signal peptide
No full textThe TBF-1 is an 11.9-kDa fruiting body specific protein of the Ascomycetes hypogeous fungus Tuber borchii Vittad. found in aqueous extract and the hyphal cell wall. The tbf-1 gene codes a 12-amino acid N-terminal stretch not present in mature protein. This sequence does not match with any homologous signal sequences stored in data banks. To investigate the role of the N-terminus in TBF-1 localization, cDNA was expressed in Saccharomyces cerevisiae under the control of the 3-phosphoglycerate kinase promoter. Like Tuber, yeast also produces and secretes TBF-1 and the foreign protein binds with the cell wall. A signalless mutant protein was constructed; this ∆TBF-1 was expressed but not exported by yeast. The secretion of TBF-1 was also suppressed using the sec18ts yeast mutant strain grown at nonpermissive temperature as host. Thus we demonstrated that the N-terminal 12-amino acid stretch is a noncanonical signal peptide that leads the TBF-1 toward the classical secretory pathway in yeast
A NONCANONICAL N-TERMINAL PEPTIDE LEADS THE TBF-1 TO THE EXPORT TOWARDS THE CLASSICAL SECRETORY PATHWAY
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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