1,721,070 research outputs found
Pólya-type estimates for the first Robin eigenvalue of elliptic operators
No full textThe aim of this paper is to obtain optimal estimates for the first Robin eigenvalue of the anisotropic p-Laplace operator, namely: (Formula presented.) where p∈]1,+∞[,Ω is a bounded, convex domain in RN,νΩ is its Euclidean outward normal, β is a real number, and F is a sufficiently smooth norm on RN. We show an upper bound for λF(β,Ω) in terms of the first eigenvalue of a one-dimensional nonlinear problem, which depends on β and on the volume and the anisotropic perimeter of Ω, in the spirit of the classical estimates of Pólya (J Indian Math Soc (NS) 24:413–419, 1961) for the Euclidean Dirichlet Laplacian. We will also provide a lower bound for the torsional rigidity (Formula presented.) when β>0. The obtained results are new also in the case of the classical Euclidean Laplacian
Epoxyfocardin and its Putative biogenetic Precursor, Focardin, Bioactive, New-Skeleton, Diterpenoids of the Marine Ciliate Euplotes focardii from Antarctica
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Rogioldiol A, a New Obtusane Diterpene, and Rogiolal, a Degraded Derivative, of the Red Seaweed Laurencia Microcladia from Il Rogiolo along the Coast of Tuscany: a Synergism in Structural Elucidation
No full textThe structure of rogioldiol A ((-)-1), isolated from the red seaweed Laurencia microcladia, was determined. Employing the exciton-coupling technique for rogioldiol A p-bromobenzoate (2), the absolute configuration at C(9) of (-)-1 was assigned, and, together with extensive NMR experiments, the absolute configuration at C(10) and preferred conformations of (-)-1 were determined. The absolute configuration of the hetero-substituted cyclohexane ring was deduced in analogy from the X-ray structure of 4. a derivative of the aldehyde 3, which was isolated from the same seaweed and is believed to be a degradation product of (-)-1
Rarisetenolide, Epoxyrarisetenolide, and Epirarisetenolide, new-skeleton sesquiterpene lactones as taxonomic markers and defensive agents of the marine ciliated morphospecies Euplotes rariseta
No full textHydrolytic breakdown of the euplotins, highly strained, adaptive, hemiacetal esters of the marine ciliate Euplotes crassus. A mimic of degradative pathway in nature and a trick for the assignment of the absolute configuration
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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
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