1,720,991 research outputs found
Cetineite, a new antimony oxide-sulfide mineral from Cetine mine, Tuscany, Italy
No full textCetineite, a new Sb oxide-sulfide mineral, occurs as tufts of acicular orange-red crystals in slag cavities in the dumps of the Cetine mine, Tuscany, Italy. Probe anal. gives a formula very similar to (K,Na)3+x(Sb2O3)3(SbS3)(OH)x (2.8-x)-H2O, with x ≈ 0.5. The mineral is hexagonal, P63, a = 14.230(2), c = 5.579(1)Å, Z = 2. The strongest lines of the x-ray powder pattern are given. The calcd. d. is 4.21 g/cm3 and the mineral is optically uniaxial (+) with birefringence 0.059; cleavage {100}; and microhardness (VHN20) 127-156 kg/mm2. The IR spectrum is reported
Coquandite, Sb6O8(SO4).H2O, a new mineral from Pereta, Tuscany, Italy, and two other localities
No full textCoquandite, a new antimony oxy-sulfate hydrate, occurs as spheroidal knobs of silky fibers or, rarely, as tiny transparent colorless lamellar crystals on stibnite at the Pereta mine, Tuscany, Italy; it is assocd. with klebelsbergite, peretaite, valentinite, sulfur, gypsum, stibiconite, and senarmontite. Coquandite is triclinic P ̅1, with a 11.434(7), b 29.77(4), c 11.314(4) Å, α 91.07(7)°, β 119.24(3)°, γ 92.82(1)°. It has a cell vol. of 3352(5) Å3 with Z = 12 and a calcd. d. of 5.78 g cm-3. The crystals, elongated along [001] and flattened on {010}, display polysynthetic twinning with (010) as the twin plane. Optically, they are biaxial (+) with z ≈ c, 2V » 60°, n = 2.08(5). The strongest lines of the x-ray powder pattern are [d in Å, (I), (hkl)] 14.84(50)(020), 9.27(41)(111, 110) 6.81(67)(130), 3.304(93)(090), 3.092(100)(330). Coquandite has also been found at the Cetine mine, Tuscany, Italy, and at the Lucky Knock mine, Tonasket, Okanogan County, Washington, USA. Microprobe chem. analyses (elemental microanal. for H) gave Sb2O3 88.91, SO3 8.35, CaO 0.04, Na2O 0.03, H2O 1.43, total 98.76 wt.%, corresponding to the empirical formula (Sb + S = 7) Sb5.98Ca0.01Na0.01O7.96(SO4)1.02.0.78H2O, and to the idealized formula Sb6O8(SO4).H2O. The IR spectrum, which confirms the presence of water in the formula, is given. A partial structural arrangement is also given: the Sb polyhedra lie in nine layers perpendicular to [010] and form 'hexagonally' shaped groups surrounded by SO4 tetrahedra
The 2(-+) assignment for the X(3872)
No full textVery recently the BABAR collaboration has put forward a claim that the X(3872) is not a 1(++) resonance, as most of the phenomenological work on the subject was relying on, but rather a 2(-+) one. We examine the consequences of this quantum number assignment for the solution of the X(3872) puzzle. The molecular interpretation appears less likely, and the conventional charmonium interpretation should be reconsidered. There are several well-known difficulties with this interpretation, to which we add a new one: the production cross section at CDF is predicted to be much smaller than that observed. We also confirm, using a relativistic string model, the conclusion from potential models that the mass of the state is not consistent with expectations. In the tetraquark interpretation the 2(-+) assignment implies a rich spectrum of partner states, although the X(3872) may be among the few which are narrow enough to be observable
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
Is the X(3872) Production Cross Section at Tevatron Compatible with a Hadron Molecule Interpretation?
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