1,721,026 research outputs found
Muon-Electron Scattering at Next-To-Next-To-Leading Order: The Hadronic Corrections
No full textThe standard model prediction for muon-electron scattering beyond leading order requires the inclusion of QCD contributions which cannot be computed perturbatively. At next-to- and next-to-next-to-leading order, they arise from one- and two-loop diagrams with hadronic vacuum polarization insertions in the photon propagator. We present their evaluation using the dispersive approach with hadronic e(+) e(-) annihilation data and estimate their uncertainty. We find that these corrections are crucial for the analysis of future high-precision muon-electron scattering data, like those of the recently proposed MUonE experiment at CERN
Materiale laminato ad elevato effetto barriera all'ossigeno
No full textUno dei maggiori problemi delle plastiche usate nel settore dell’imballaggio è la loro relativamente scarsa barriera ai gas ed in particolare all’ossigeno. Lo scopo di questo brevetto è la messa a punto di un coating ibrido organico-inorganico a base di PVA e alcossidi di silicio. Questi due composti in soluzione acquosa in ambiente leggermente acido formano una lacca che può essere depositata a spruzzo o mediante stampa su substrati plastici. In alcuni casi (PE, PP) la superficie deve essere attivata mediante effetto corona. La soluzione depositata mediante un leggero riscaldamento dà origine ad un film solido, ma molto elastico che migliora di molto le proprietà barriera. Lo spessore del film dopo trattamento termico è inferiore ad 1 micron. D esempio, la barriera all’ossigeno del PET non ricoperto passa da 30-90 cc/(m2*day) a 0,05-0,5 cc/(m2*day) quando ricoperto con il coating, migliore o uguale ai multistrato contenenti EVOH comunemente utilizzati. Rispetto a questi ultimi materiali i film su cui è stato depositato il coating in oggetto hanno un peso inferiore, quindi parità di superficie trattata si ha un peso inferiore, con risparmio di materiale plastico e conseguentemente con un beneficio ambientale. Inoltre il coating depositato può essere sottoposto a processi di stampa oppure di incollaggio senza alcun problema. La velocità di deposizione su bobine è superiore a 200 m/min
Antifungal susceptibility profiles of Candida isolates from a prospective survey of invasive fungal infections in Italian intensive care units
No full textThe antifungal susceptibility pattern of 302 Candida isolates collected during an Italian survey on invasive fungal infections in an intensive care setting was investigated. The results were correlated with some epidemiological data and compared with the antifungal profiles obtained in a previous survey. No resistance to echinocandins was detected. The overall resistance levels to fluconazole, posaconazole and voriconazole were 12.6, 6.0 and 7.1 %, respectively. Candida tropicalis and Candida parapsilosis accounted for more than half of all the fluconazole resistant isolates. Reduced susceptibility to fluconazole is not uncommon among isolates (12.3 %) and appears to be increasing, particularly among C. parapsilosis isolates, which showed an increase in resistant isolates from 2 % in the 1990s to 25.8 % in the present study. Routine antifungal susceptibility testing of this species is therefore recommended
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
tau dipole moments via radiative leptonic tau decays
No full textWe propose a new method to probe the magnetic and electric dipole moments of the tau lepton using precise measurements of the differential rates of radiative leptonic tau decays at high-luminosity B factories. Possible deviations of these moments from the Standard Model values are analyzed in an effective Lagrangian approach, thus providing model-independent results. Analytic expressions for the relevant non-standard contributions to the differential decay rates are presented. Earlier proposals to probe the tau dipole moments are examined. A detailed feasibility study of our method is performed in the conditions of the Belle and Belle II experiments at the KEKB and Super-KEKB colliders, respectively. This study shows that our approach, applied to the planned full set of Belle II data for radiative leptonic tau decays, has the potential to improve the present experimental bound on the tau anomalous magnetic moment. On the contrary, its foreseen sensitivity is not expected to lower the current experimental limit on the tau electric dipole moment
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
Radiative μ and τ leptonic decays at NLO
No full textWe present the differential rates and branching ratios of the radiative decays tau -> l nu nu gamma, with l = e or mu, and mu -> e nu nu gamma in the Standard Model at next-to-leading order. Radiative corrections are computed taking into account the full depencence on the mass m l of the final charged leptons, which is necessary for the correct determination of the branching ratios. Only partial agreement is found with previous calculations performed in the m(l) -> 0 limit. Our results agree with the measurements of the branching ratios B (mu -> e (nu) over bar nu gamma) and B (tau -> mu(nu) over bar nu gamma) for a minimum photon energy of 10MeV in the mu and tau rest frames, respectively. BABAR's recent precise measurement of the branching ratio B (tau -> e (nu) over bar nu gamma), for the same photon energy threshold, differs from our prediction by 3.5 standard deviations
New physics at the MUonE experiment at CERN
Full text linkA confirmation of the long-standing muon g-2 discrepancy requires both experimental and theoretical progress. On the theory side, the hadronic corrections are under close scrutiny, as they induce the leading uncertainty of the Standard Model prediction. Recently, the MUonE experiment has been proposed at CERN to provide a new determination of the leading hadronic contribution to the muon g-2 via the measurement of the differential cross section of muon-electron scattering. The precision expected at this experiment raises the question whether possible new physics (NP) could affect its measurements. We address this issue studying possible NP signals in muon-electron collisions due to heavy or light mediators, depending on whether their mass is higher or lower than O(1 GeV). We analyze the former in a model-independent way via an effective field theory approach, whereas for the latter we focus on scenarios with light scalar and vector bosons. Using existing experimental bounds, we show that possible NP effects in muon-electron collisions are expected to lie below MUonE’s sensitivity. This result confirms and reinforces the physics case of the MUonE proposal.A confirmation of the long-standing muon -2 discrepancy requires both experimental and theoretical progress. On the theory side, the hadronic corrections are under close scrutiny, as they induce the leading uncertainty of the Standard Model prediction. Recently, the MUonE experiment has been proposed at CERN to provide a new determination of the leading hadronic contribution to the muon -2 via the measurement of the differential cross section of muon-electron scattering. The precision expected at this experiment raises the question whether possible new-physics (NP) could affect its measurements. We address this issue studying possible NP signals in muon-electron collisions due to heavy or light mediators, depending on whether their mass is higher or lower than . We analyze the former in a model-independent way via an effective field theory approach, whereas for the latter we focus on scenarios with light scalar and vector bosons. Using existing experimental bounds, we show that possible NP effects in muon-electron collisions are expected to lie below MUonE's sensitivity. This result confirms and reinforces the physics case of the MUonE proposal
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