139 research outputs found

    Wood Properties of Twenty Highly Ranked Radiata Pine Seed Production Parents Selected for Growth and Form

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    Twenty highly ranked radiata pine (Pinus radiata D. Don) seed production parent trees, grown under a commercial sawlog regime, were destructively assessed at rotation age (27 years) for wood quality traits significant to solid-wood and veneer products, including: juvenile-wood density, density variation, juvenile-wood spiral grain, compression wood, and appearance characteristics such as within-ring internal checking and resin pockets. Traits varied considerably among parents, which is reasonable since breeding efforts in New Zealand have, until recently, focused primarily on stem productivity and form. Parental information is useful for many wood properties owing to their high heritabilities in radiata pine (usually 50-80%); thus production forests established using advanced-generation genetic materials can also be expected to be variable in wood properties. Like other fastgrown pines, much of the radiata pine crop is juvenile wood, and an important challenge for tree improvement is to ensure that juvenile wood properties meet processor and end-user requirements

    Interplay between Kondo suppression and Lifshitz transitions in YbRh2_2Si2_2 at high magnetic fields

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    We investigate the magnetic field dependent thermopower, thermal conductivity, resistivity and Hall effect in the heavy fermion metal YbRh2Si2. In contrast to reports on thermodynamic measurements, we find in total three transitions at high fields, rather than a single one at 10 T. Using the Mott formula together with renormalized band calculations, we identify Lifshitz transitions as their origin. The predictions of the calculations show that all experimental results rely on an interplay of a smooth suppression of the Kondo effect and the spin splitting of the flat hybridized bands.Comment: 5 pages, 4 figure

    Quantum Tricritical Points in NbFe2_2

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    Quantum critical points (QCPs) emerge when a 2nd order phase transition is suppressed to zero temperature. In metals the quantum fluctuations at such a QCP can give rise to new phases including unconventional superconductivity. Whereas antiferromagnetic QCPs have been studied in considerable detail ferromagnetic (FM) QCPs are much harder to access. In almost all metals FM QCPs are avoided through either a change to 1st order transitions or through an intervening spin-density-wave (SDW) phase. Here, we study the prototype of the second case, NbFe2_2. We demonstrate that the phase diagram can be modelled using a two-order-parameter theory in which the putative FM QCP is buried within a SDW phase. We establish the presence of quantum tricritical points (QTCPs) at which both the uniform and finite qq susceptibility diverge. The universal nature of our model suggests that such QTCPs arise naturally from the interplay between SDW and FM order and exist generally near a buried FM QCP of this type. Our results promote NbFe2_2 as the first example of a QTCP, which has been proposed as a key concept in a range of narrow-band metals, including the prominent heavy-fermion compound YbRh2_2Si2_2.Comment: 21 pages including S

    Interplay between unconventional superconductivity and heavy-fermion quantum criticality: CeCu2_2Si2_2 versus YbRh2_2Si2_2

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    In this paper the low-temperature properties of two isostructural canonical heavy-fermion compounds are contrasted with regards to the interplay between antiferromagnetic (AF) quantum criticality and superconductivity. For CeCu2_2Si2_2, fully-gapped d-wave superconductivity forms in the vicinity of an itinerant three-dimensional heavy-fermion spin-density-wave (SDW) quantum critical point (QCP). Inelastic neutron scattering results highlight that both quantum critical SDW fluctuations as well as Mott-type fluctuations of local magnetic moments contribute to the formation of Cooper pairs in CeCu2_2Si2_2. In YbRh2_2Si2_2, superconductivity appears to be suppressed at T≳ 10T\gtrsim~10 mK by AF order (TNT_N = 70 mK). Ultra-low temperature measurements reveal a hybrid order between nuclear and 4f-electronic spins, which is dominated by the Yb-derived nuclear spins, to develop at TAT_A slightly above 2 mK. The hybrid order turns out to strongly compete with the primary 4f-electronic order and to push the material towards its QCP. Apparently, this paves the way for heavy-fermion superconductivity to form at TcT_c = 2 mK. Like the pressure - induced QCP in CeRhIn5_5, the magnetic field - induced one in YbRh2_2Si2_2 is of the local Kondo-destroying variety which corresponds to a Mott-type transition at zero temperature. Therefore, these materials form the link between the large family of about fifty low-TT unconventional heavy - fermion superconductors and other families of unconventional superconductors with higher TcT_cs, notably the doped Mott insulators of the cuprates, organic charge-transfer salts and some of the Fe-based superconductors. Our study suggests that heavy-fermion superconductivity near an AF QCP is a robust phenomenon.Comment: 30 pages, 7 Figures, Accepted for publication in Philosophical Magazin

    Channelling figurativity through narrative : the paranarrative in fiction and non-fiction

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    Contrary to wide-spread assumptions, metaphor in narrative is not a pre-established, extra-textual form appearing in different instances of discourse, but rather an event resulting from a strategic distribution of information in the narrative process. Hence, the appeal to conceptual cultural knowledge is to be considered as a consequence, and not as a prerequisite of metaphor interpretation. By means of the concept of the paranarrative, we highlight the rhetorical interconnectedness of metaphor with other figures of speech (such as metonymy) and we explore the narrative integration of diacritic forms of indirectness. In order to illustrate the terminology that can address these focal concerns, the paper discusses the relation between tropes and narrative, via selected examples from narrative texts (both fictional and non-fictional) written by Juli Zeh, Herta Müller, Jürgen Nieraad, and Siddhartha Mukherjee. As their common denominator, these examples channel through narrative figurative domains considered to be known intuitively to wit: personifications; iconic pars pro toto references to concentration camps; and metaphors for cancer in disease biographies

    Quantum tricritical points in NbFe2

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    Quantum critical points (QCPs) emerge when a 2nd order phase transition is suppressed to zero temperature. In metals the quantum fluctuations at such a QCP can give rise to new phases including unconventional superconductivity. Whereas antiferromagnetic QCPs have been studied in considerable detail ferromagnetic (FM) QCPs are much harder to access. In almost all metals FM QCPs are avoided through either a change to 1st order transitions or through an intervening spin-density-wave (SDW) phase. Here, we study the prototype of the second case, NbFe2_2. We demonstrate that the phase diagram can be modelled using a two-order-parameter theory in which the putative FM QCP is buried within a SDW phase. We establish the presence of quantum tricritical points (QTCPs) at which both the uniform and finite qq susceptibility diverge. The universal nature of our model suggests that such QTCPs arise naturally from the interplay between SDW and FM order and exist generally near a buried FM QCP of this type. Our results promote NbFe2_2 as the first example of a QTCP, which has been proposed as a key concept in a range of narrow-band metals, including the prominent heavy-fermion compound YbRh2_2Si2_2

    Tropological space : the imaginary space of figuration

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    The paper is devoted to the concept of tropological space, introduced by Michel Foucault in 1966 and alluded to in Hayden White’s tropics of discourse (1973, 1978, 2000), but never described in any detail in literary semantics or linguistic stylistics. The author presents her theory of a triple functional subdivision of stylistic figures and, consequently, of tropes (micro-, macro- and mega (meta)-level of description) and relates it to a gradually expanding tropological space of particular figures, their chains and groupings within a text. The author postulates that tropological space, the imaginary space created through figuration, is a sub-space of the Wittgensteinian logical space as well as a sub-space of textual / discursive space. Although the discussion refers mostly to literary texts, tropology – a branch of stylistics / poetics / rhetoric makes generalizations valid for the study of all kinds of texts / discourses. Figuration is assumed here to be an inherent feature of conceptual and linguistic expression. Finally, the author raises a methodological query as to the ontological status of tropological space, opting for the approach which treats it as a peculiar kind of semantic space rather than a mere metaphoric term. The discussion is based mostly on the Anglo-American studies on figuration (K. Burke, H. White, P. de Man, J. Hillis Miller, G. Hartman) that are rooted in the neo-classical rhetoric and writings of G. Vico. This line of thinking draws its philosophical inspiration from the European hermeneutics of P. Ricoeur, the Foucaultian theory of discourses and the Derridean deconstructionist ideas on the operation of language. The author brings additionally into consideration the conception of artistic space propagated by the Russian semiotic tradition and V. N. Toporov (1983/2003) in particular

    The Swiss Preschoolers’ health study (SPLASHY): objectives and design of a prospective multi-site cohort study assessing psychological and physiological health in young children

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