189,594 research outputs found
Wulff Steiner polynomial for ovaloid
No full textThe equilibrium shape of a crystal is the celebrated Wulff shape W, which can be obtained via the Wulff flow. When the initial crystal K is convex, the image under the Wulff flow is K + tW after time t. The n + 1-dimensional volume Vn+1(K + tB) is the well known Steiner polynomial , where B is the closed unit ball.Wulff flow and Wulff shape has been highly studied in crystal growth. Ge-ometric information encoded in the the associated Wulff-Steiner polynomial was far from being thoroughly understood.In this thesis, Wulff-Steiner polynomial of degree 2 was surveyed. We ob-tained a characterization of them. The relative positions among the roots , the W-inradius, W-outradius and other geometric quantities are studied. Wulff-Steiner polynomial have no positive real root by its definition. For degree 2, the fact that it must have negative real roots is equivalent to the classi-cal isoperimetric inequality. For degree 3, we showed that complex roots can occur and that the real parts of any complex root must be negative. As an application of the Wulff-Steiner polynomial, we found an invariant under the Wulff flow in any dimension n ≥ 2.</p
Self-dual polytope and self-dual smooth Wulff shape
No full textFor any Wulff shape , its dual Wulff shape and spherical Wulff
shape can be defined naturally. A self-dual Wulff
shape is a Wulff shape equaling its dual Wulff shape exactly. In this paper, we
show that if a spherical convex polytope is of constant width ,
then . As an application of this fact, we prove that a polytope
Wulff shape is self-dual if and only if its spherical Wulff shape is a
spherical convex body of constant width. We also prove that a smooth Wulff
shape is self-dual if and only if for any interior point of
and for any point of the intersection of the
boundary of and the graph of its spherical support
function (with respect to ), the image of under the spherical blow-up
(with respect to ) is always a boundary point of .Comment: 8page
El uso del software HistCite para identificar artículos significativos en búsquedas por materias en la Web of Science
No full textHistCiteTM is a large-scale computer tool for mapping science. Its power of visualization combines
the production of historiographs on the basis of the analysis of co-citations of documents, with the
use of bibliometrics specific indicators. The objective of this article is, to present the advantages of
the new bibliometrics configuration of HistCiteTM (2004) when identifying articles to analyze the
histograms that produces HistCiteTM, in terms of cumulative advantage and aging of the citations
to do a comparative study of the results of HistCiteTM, in its indicators of amplitude and recognition.
Also is examined its treatment of the sampling problems, by formalizing the question of
Kendall
Kinetic and Thermodynamic Modified Wulff Constructions for Twinned Nanoparticles
No full textWulff
constructions are a powerful tool to predict the shape of
nanoparticles, which strongly influences their performance in catalysis,
sensing, and surface-enhanced spectroscopies. Previous Wulff models
focused on energy minimization and included contributions from the
surface energy, interface energy, twin boundaries, and segregation-induced
bulk energy changes. However, a large number of shapes cannot be understood
by such thermodynamic approaches, in particular many of the twinned
late transition metal (Ag, Au, Pt, Pd, etc.) particles of interest
in catalysis and plasmonics. A review of the modified Wulff (i.e.,
twinned) construction is presented here, followed by the development
of a modified kinetic Wulff model, which, by including kinetic parameters,
explains the emergence of commonly observed shapes such as bitetrahedra,
truncated bitetrahedra, thin triangular platelets, perfect decahedra,
and decahedral rods
Diversifying from within
No full textHelena Wulff´s chapter begins with an essay drawing on her ongoing literary anthropological study of diaspora fiction writers and their work in Sweden who, she argues, are diversifying the country from within. The essay engages with the work of Pooneh Rohi born in Iran, who is a new voice while Jonas Hassen Khemiri, of Tunisian background, is an established writer. In addition to writing fiction, they sometimes do journalism. By uncovering often cruel experiences of racism in a country which boasts an inclusive policy, yet has an expanding anti-immigration party (the Sweden Democrats) diaspora writers have an impact on political and cultural debate in Sweden, also because they take on the role as public intellectuals. In her Commentary, Wulff explains how Text came about, how it goes back to her intellectual history that was founded during her upbringing when she first became a habitual reader, and later with her education in comparative literature and anthropology that eventually would make her an anthropological writer. Inspired by her research on the ballet world where desire and technique are key for creativity to spring up, Wulff suggests that this is the case in anthropological writing, as well. As to the recent genealogy of the essay, it is an account of preparations for a major multi-disciplinary research program on world literatures which was funded in 2016. </p
Wulff Construction for Alloy Nanoparticles
No full textThe Wulff construction is an invaluable tool to understand and predict the shape of nanoparticles. We demonstrate here that this venerable model, which gives a size-independent thermodynamic shape, becomes size dependent in the nanoscale regime for an alloy and that the infinite reservoir approximation breaks down. The improvements in structure and energetic modeling have wide-ranging implications both in areas where energetics govern (e.g., nucleation and growth) and where the surface composition is important (e.g., heterogeneous catalysis)
WulffPack – a package for Wulff constructions
No full text<p><strong>WulffPack</strong> is a tool for making Wulff constructions, typically for minimizing the energy of nanoparticles. A detailed description of the functionality provided as well as an extensive tutorial can be found in the <a href="https://wulffpack.materialsmodeling.org" target="_blank" rel="noopener">user guide</a>.</p>
<p><strong>WulffPack</strong> constructs both continuum models and atomistic structures for further modeling with, e.g., molecular dynamics or density functional theory.</p>
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Multi-publication data set on experienced-based and description-based risky choice
No full textThe data of 28 publications studying the description-experience gap, involving experience- and description-based risky choices, that served as the basis for the meta analysis reported in Wulff, D. U., Mergenthaler-Canseco, M., & Hertwig, R. (2018). A meta-analytic review of two modes of learning and the description-experience gap. Psychological Bulletin, 144(2), 140-176.</p
Rhoicosphenia johannessoniae Al-Handal, Levkov & Wulff 2023, sp. nov.
No full text<i>Rhoicosphenia johannessoniae</i> Al-Handal, Levkov & Wulff <i>sp. nov</i>. (Figs 1–11, 12–25) Description <p> <b>LM observation (Figs 1–11):</b> Valves heteropolar, narrowly clavate, 29–48 μm long and 6.8–8.5 μm wide. Head pole narrowly rounded, base pole protracted to elongated subcapitate with rounded apex. Raphe filiform on the R-valve with distinct proximal endings (Figs 1–5), but not resolvable on the D-valve (Figs 6–10). Axial area linear and very narrow on R-valve with indistinct central area. D-valve axial area narrowly linear lanceolate. Striae on both valves parallel to slightly radiate, 20–22 in 10 μm. Areolae not discernible in LM. Frustules in girdle view bent and wedge shaped (Fig. 11).</p> <p> <b>SEM observations (Figs 12–25):</b> R-valves: Valves concave and narrowly clavate with broadly rounded poles (Figs 12, 13). Externally, head poles broadly rounded (Figs 16, 18), base pole narrowly rounded and protracted, with pore field of irregularly arranged poroids, formed of 11–12 rows.Axial area linear and asymmetric, becoming narrower near poles (Fig. 12). Central area slightly wider than axial area, and in some specimens, ornamented with small porelike depressions that do not penetrate internally (Figs 12, 17). Central area not located in valve centre but positioned below the wider middle part of the valve towards the base pole (Fig. 12). Raphe filiform, proximal endings small, droplike and distantly spaced (Fig. 17). Distal raphe endings curved and terminate on valve mantle (Fig. 16). Striae parallel to slightly radiate and formed of slit-like, weakly curved areolae (Figs 13, 16). Internally, pseudosepta on both poles large and strongly silicified (Fig. 14). Axial area lanceolate, gradually widens into a large central area. Raphe proximal endings strongly hooked (Fig.15). Striae weakly radiate in valve centre and separated by well-developed virgae (Fig. 15). D-Valves: Valves concave, narrowly clavate with rounded poles (Figs 19–21). Base pole protracted with 10–12 irregularly arranged rows of poroids which form pore field (Figs 20, 21, 23). Axial area linear, very narrow, slightly widened towards mid- valve (Fig. 20). Raphe system reduced, the upper raphe fissure very short, slightly bent, extends for 4–5 striae and positioned near the head pole (Fig. 24). Raphe fissure at base pole straight, longer than upper fissure with weakly curved distal endings that reach valve margin (Fig. 23). Striae parallel, formed of slit-like areolae, occasionally biseriate stria formed near valve margin (Figs 21, 22). Internally, head pole rounded (Fig. 19), while base pole rostrate (Fig. 25). Axial area linear-lanceolate. Proximal raphe endings crook-shaped (Fig. 25). Striae parallel, narrow in mid- valve and wider toward poles (Fig. 19). Pseudosepta of base pole interrupted by lacuna which terminate before valve apex with rounded and slightly bent structure (Fig. 25).</p> <p> <b>Type:</b> Grisslehamn port, Baltic coast of Sweden, 60° 05’ 53’’ N, 18° 48’ 47’’ E, Collectors: Adil Al-Handal and Mikael Hedblom, collection date: May 2019. Permanent slide containing cells of <i>R. johannessoniae</i> is deposited at the Macedonian National Diatom collection under accession No. MKNDC 014457. Figures 2 and 7 represent the holotype.</p> <p> <b>Isotype</b>: Permanent slide containing cells of <i>R. johannessoniae</i> is deposited at the University of Gothenburg Herbarium under No. GB-0210437.</p> <p> <b>Etymology</b>: The epithet is in honour of Professor Kerstin Johannesson of the Tjärnö Marine Laboratory, University of Gothenburg for her contribution and outstanding work on the ecology and phylogeny of some marine benthic invertebrate in Sweden.</p> <p> <b>Ecology</b>: <i>Rhoicosphenia johannessoniae</i> was rather rare and constituted 0.8% of the diatom association in the sample examined. It is a brackish water species found epiphytic on the brown macrophyte <i>Ectocarpus siliculosus</i> and did not appear on other macrophytes collected from the same region or in the benthic samples. Water temperature was 12.3 °C and salinity 4.9 psu. Several other species were associated with <i>R. johannessoniae</i> including <i>Licmophora gracilis</i> (Ehrenberg) Grunow (1867:34, 24.6%), <i>Licmophora ehrenbergii</i> (Kützing) Grunow (1867: 36, 10.2%), <i>Entomoneis paludosa</i> (W.Smith) Reimer 1975: 4, 5.3%), <i>Diatoma tenuis</i> C. Agardh (1812: 15, 3.4%), <i>Tabularia fasciculata</i> (C.Agardh) Williams & Round (1986:326, 2.7%), together with small-sized <i>Navicula</i> spp. and <i>Nitzschia</i> spp.</p>Published as part of <i>Al-Handal, Adil Y., Levkov, Zlatko & Wulff, Angela, 2023, Rhoicosphenia johannessoniae (Bacillariophyceae), a new diatom from the Swedish coast of the Baltic Sea, pp. 69-78 in Phytotaxa 618 (1)</i> on pages 71-73, DOI: 10.11646/phytotaxa.618.1.6, <a href="http://zenodo.org/record/8389927">http://zenodo.org/record/8389927</a>
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