44 resultados para Symbols


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The first IUPAC Manual of Symbols and Terminology for Physicochemical Quantities and Units (the Green Book) of which this is the direct successor, was published in 1969, with the object of 'securing clarity and precision, and wider agreement in the use of symbols, by chemists in different countries, among physicists, chemists and engineers, and by editors of scientific journals'. Subsequent revisions have taken account of many developments in the field, culminating in the major extension and revision represented by the 1988 edition under the simplified title Quantities, Units and Symbols in Physical Chemistry. This 2007, third edition, is a further revision of the material which reflects the experience of the contributors with the previous editions. The book has been systematically brought up to date and new sections have been added. It strives to improve the exchange of scientific information among the readers in different disciplines and across different nations. In a rapidly expanding volume of scientific literature where each discipline has a tendency to retreat into its own jargon this book attempts to provide a readable compilation of widely used terms and symbols from many sources together with brief understandable definitions. This is the definitive guide for scientists and organizations working across a multitude of disciplines requiring internationally approved nomenclature.

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The importance of maintaining a clear distinction between the names and symbols for quantities and the names and symbols for units.

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We study the boundedness and compactness of Toeplitz operators Ta on Bergman spaces , 1 < p < ∞. The novelty is that we allow distributional symbols. It turns out that the belonging of the symbol to a weighted Sobolev space of negative order is sufficient for the boundedness of Ta. We show the natural relation of the hyperbolic geometry of the disc and the order of the distribution. A corresponding sufficient condition for the compactness is also derived.

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We characterize the essential spectra of Toeplitz operators Ta on weighted Bergman spaces with matrix-valued symbols; in particular we deal with two classes of symbols, the Douglas algebra C+H∞ and the Zhu class Q := L∞ ∩VMO∂ . In addition, for symbols in C+H∞ , we derive a formula for the index of Ta in terms of its symbol a in the scalar-valued case, while in the matrix-valued case we indicate that the standard reduction to the scalar-valued case fails to work analogously to the Hardy space case. Mathematics subject classification (2010): 47B35,

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We study the boundedness of Toeplitz operators $T_a$ with locally integrable symbols on Bergman spaces $A^p(\mathbb{D})$, $1 < p < \infty$. Our main result gives a sufficient condition for the boundedness of $T_a$ in terms of some ``averages'' (related to hyperbolic rectangles) of its symbol. If the averages satisfy an ${o}$-type condition on the boundary of $\mathbb{D}$, we show that the corresponding Toeplitz operator is compact on $A^p$. Both conditions coincide with the known necessary conditions in the case of nonnegative symbols and $p=2$. We also show that Toeplitz operators with symbols of vanishing mean oscillation are Fredholm on $A^p$ provided that the averages are bounded away from zero, and derive an index formula for these operators.

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Those who study Roman art and religion in Britain will know that there are a relatively small number of pieces in stone and bronze which are regularly used to illustrate arguments on Romanization, provincialism and identity. However, while these objects become familiar through such use, they are, in fact, often little studied as pieces in their own right and the only description of their appearance and context are some fifty or more years old. Re-excavation of the context from which the Silchester eagle was recovered has raised questions about the date of its deposition, as well as its origin and use, and indeed the nature of its deposition at Silchester. This paper examines the figurine in detail, the role of the eagle at Silchester and explores the significance of the eagle more widely in Roman Britain.

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Those who study Roman art and religion in Britain will know that there are a relatively small number of pieces in stone and bronze which are regularly used to illustrate arguments on Romanization, provincialism and identity. However, while these objects become familiar through such use, they are, in fact, often little studied as pieces in their own right and the only description of their appearance and context are some fifty or more years old. Re-excavation of the context from which the Silchester eagle was recovered has raised questions about the date of its deposition, as well as its origin and use, and indeed the nature of its deposition at Silchester. This paper examines the figurine in detail, the role of the eagle at Silchester and explores the significance of the eagle more widely in Roman Britain.

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The study investigated early years teachers’ understanding and use of graphic symbols, defined as the visual representation(s) used to communicate one or more “linguistic” concepts, which can be used to facilitate science learning. The study was conducted in Cyprus where six early years teachers were observed and interviewed. The results indicate that the teachers had a good understanding of the role of symbols, but demonstrated a lack of understanding in regards to graphic symbols specifically. None of the teachers employed them in their observed science lesson, although some of them claimed that they did so. Findings suggest a gap in participants’ acquaintance with the terminology regarding different types of symbols and a lack of awareness about the use and availability of graphic symbols for the support of learning. There is a need to inform and train early years teachers about graphic symbols and their potential applications in supporting children’s learning.

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Despite the fact that the Harry Potter books have won a place in the cultural consciousness and have had enjoyed immense commercial success, they were not accepted within many faith groups at the outset. Using the term ‘religion’ to refers to any system of belief that may be recognised by symbols , I look extracts from three of the novels, alongside their subsequent cinematic adaptations, in order to consider the construction of representations of religion in the films and the contribution made by the films to this debate.

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The field of Molecular Spectroscopy was surveyed in order to determine a set of conventions and symbols which are in common use in the spectroscopic literature. This document, which is Part I in a series, establishes the notations and conventions used for general spectroscopic notations and deals with quantum mechanics, quantum numbers (vibrational states, angular momentum and energy levels), spectroscopic transitions, and miscellaneous notations (e.g. spectroscopic terms). Further parts will follow, dealing inter alia with symmetry notation, permutation and permutation-inversion symmetry notation, vibration-rotation spectroscopy and electronic spectroscopy.