1,721,050 research outputs found
Vapor d'acqua e reazioni esotermiche per il contenimento di patogeni tellurici: esperienze su Sclerotinia minor Jagger e Rhizoctonia solani Khun
No full textThe absence of cross tolerance between ozone and paraquat: The case of Conyza bonariensis
No full textThe behavior of two biotypes of the composite weed Conyza bonariensis, resistant and sensitive to paraquat (PQ), exposed to PQ (10 ppm) or to ozone (O3, 50-250 ppb, 5 h) was investigated by examining the fluctuation in gas exchange parameters and chlorophyll content, as well as membrane integrity and antioxidant enzyme activities. The two biotypes proved not to be different for the variables tested under undisturbed conditions, with the exception of intercellular CO2 concentration, the resistant biotype showing the highest constitutive values. Even thought necrotic lesions developed similarly in both biotypes upon treatment with PQ or O3, changes in malondialdehyde formation, superoxide dismutase and peroxidase system activities were significantly different
Normal state of a polarized Fermi gas at unitarity
Full text linkWe study the Fermi gas at unitarity and at T=0 by assuming that, at high polarizations, it is a normal Fermi liquid composed of weakly interacting quasiparticles associated with the minority spin atoms. With a quantum Monte Carlo approach we calculate their effective mass and binding energy, as well as the full equation of state of the normal phase as a function of the concentration x=n?/n? of minority atoms. We predict a first order phase transition from normal to superfluid at xc=0.44 corresponding, in the presence of harmonic trapping, to a critical polarization Pc=(N?-N?)/(N?+N?)=77%. We calculate the radii and the density profiles in the trap and predict that the frequency of the spin dipole mode will be increased by a factor of 1.23 due to interaction
UPPER-BOUNDS ON PLASMON DISPERSION IN THE DEGENERATE BOSON PLASMA
No full textSum-rule arguments are used to derive two rigorous upper bounds for the plasmon dispersion curve in a fluid of charged bosons at zero temperature. They are readily evaluated (i) at long wavelengths, to show that the leading dispersion coefficient is negative at all couplings, and (ii) at weak coupling, to obtain a simple analytic upper bound for the whole dispersion curve
Role of interactions in spin-polarized atomic Fermi gases at unitarity
No full textWe study the zero temperature properties of a trapped polarized Fermi gas at unitarity by assuming phase separation between an unpolarized superfluid and a polarized normal phase. The effects of the interaction are accounted for using the formalism of quasiparticles to build up the equation of state of the normal phase with the Monte Carlo results for the relevant parameters. Our predictions for the Chandrasekhar-Clogston limit of critical polarization and for the density profiles, including the density jump at the interface, are confirmed with excellent accuracy by the recent experimental results at MIT. The role of interaction on the radial width of the minority component, on the gap of spectral functions, and on the spin oscillations in the normal phase is also discussed. Our analysis points out the Fermi liquid nature of these strongly interacting spin-polarized configurations
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
Dipole polarizability of a trapped superfluid Fermi gas
Full text linkThe polarization produced by the relative displacement of the potentials trapping two spin species of a dilute Fermi gas with N?=N? is calculated at unitarity by assuming phase separation between the superfluid and a polarized phase at zero temperature. Because of the energy cost associated with pair breaking, the dipole polarizability is strongly quenched and exhibits important deviations from the ideal gas behavior even for nonlinear displacements of the order of the size of the atomic cloud. The behavior in the presence of different trapping frequencies (monopole polarization) for the two spin species is also discussed. Our results suggest new experimental perspectives to explore the quantum phases of interacting Fermi gase
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
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