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141.
142.
The vertical position of the larynx seems to be relevant to voicefunction. As a high vertical larynx position is often seen in hyperfunctional and strained voices, a lowering of a habitually elevated larynx is sometimes a specific goal in clinical voice therapy and different larynx-lowering exercises are used to achieve this goal. Earlier investigations have shown that pitch and to some extent also vocal loudness are relevant to vertical larynx position. In the present investigation, we examine if lung volume affects vertical larynx position. Using a multi-channel electroglottograph, the larynx position was measured in 29 healthy, vocally untrained subjects, who phonated at different lung volumes, pitches, and degrees of vocal loudness. The main results were that high lung volume was clearly associated with a lower larynx position as compared to low lung volume. In addition, vertical larynx position was strongly correlated with pitch. Both of these dependencies were shown to be stronger in males than in females. Our results suggest that lung volume is a factor that is highly relevant to larynx height in untrained subjects. 相似文献
143.
Richard G. Compton R.Geoffrey Wellington Peter J. Dobson Peter A. Leigh 《Journal of Electroanalytical Chemistry》1994,370(1-2)
Gold microband channel electrodes (30 μ m in length) are used to study the reduction of ortho- bromonitrobenzene in dimethylformamide solution. An ECE mechanism is shown to operate and a rate constant of 250 s−1 for the chemical step is deduced. The ability to distinguish between ECE and DISP1 processes with the experimental protocol adopted is noted. 相似文献
144.
G.J. Leigh 《Journal of organometallic chemistry》1983,252(1):c15-C17
Piperylene reacts with (Lig)Ni0 compounds in the presence of CO2 to give isomeric nickela complexes IV. The mixture of the isomers reacts with maleic anhydride to produce sorbic acid directly. 相似文献
145.
The need for acidic activation in the stoichiometric hydrogenation of benzyl-[1-phenyl-ethylidene]-amine (6a) or [1-(4-methoxy-phenyl)-ethylidene]-methyl-amine (6b) by Noyori's catalyst [p-Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3) (2) is inconsistent with the proposed concerted mechanism and supports an ionic mechanism. 相似文献
146.
Wood ME Penny MJ Steere JS Horton PN Light ME Hursthouse MB 《Chemical communications (Cambridge, England)》2006,(28):2983-2985
A radical-based approach facilitates the highly stereocontrolled functionalisation of beta-amino alcohols, opening up a new, generally applicable methodology for the preparation of quaternary alpha-amino acids. 相似文献
147.
Lockard JV Valverde G Neuhauser D Zink JI Luo Y Weaver MN Nelsen SF 《The journal of physical chemistry. A》2006,110(1):57-66
Excited state mixed valence (ESMV) occurs in molecules in which the ground state has a symmetrical charge distribution but the excited state possesses two or more interchangeably equivalent sites that have different formal oxidation states. Although mixed valence excited states are relatively common in both organic and inorganic molecules, their properties have only recently been explored, primarily because their spectroscopic features are usually overlapped or obscured by other transitions in the molecule. The mixed valence excited state absorption bands of 2,3-di-p-anisyl-2,3-diazabicyclo[2.2.2]octane radical cation are well-separated from others in the absorption spectrum and are particularly well-suited for detailed analysis using the ESMV model. Excited state coupling splits the absorption band into two components. The lower energy component is broader and more intense than the higher energy component. The absorption bandwidths are caused by progressions in totally symmetric modes, and the difference in bandwidths is caused by the coordinate dependence of the excited state coupling. The Raman intensities obtained in resonance with the high and low energy components differ significantly from those expected based on the oscillator strengths of the bands. This unexpected observation is a result of the excited state coupling and is explained by both the averaging of the transition dipole moment orientation over all angles for the two types of spectroscopies and the coordinate-dependent coupling. The absorption spectrum is fit using a coupled two-state model in which both symmetric and asymmetric coordinates are included. The physical meaning of the observed resonance Raman intensity trends is discussed along with the origin of the coordinate-dependent coupling. The well-separated mixed valence excited state spectroscopic components enable detailed electronic and resonance Raman data to be obtained from which the model can be more fully developed and tested. 相似文献
148.
The goal of this paper is to study ergodic and rigidity properties of smooth actions of the discrete Heisenberg group \(\mathcal{H}\). We establish the decomposition of the tangent space of any C∞ compact Riemannian manifold M for Lyapunov exponents, and show that all Lyapunov exponents for the central elements are zero. We obtain that if an \(\mathcal{H}\) action contains an Anosov element, then under certain conditions on the eigenvalues of this element, the action of each central element is of finite order. In particular, there is no faithful codimension one Anosov Heisenberg group action on any compact manifold, and there is no faithful codimension two Anosov Heisenberg group action on tori. In addition, we show smooth local rigidity for higher rank ergodic \(\mathcal{H}\) actions by toral automorphisms, using a generalization of the KAM (Kolmogorov–Arnold–Moser) iterative scheme. 相似文献
149.
The first attempt at a systematic approach to axiomatic theories of truth was undertaken by Friedman and Sheard (Ann Pure Appl Log 33:1–21, 1987). There twelve principles consisting of axioms, axiom schemata and rules of inference, each embodying a reasonable property of truth were isolated for study. Working with a base theory of truth conservative over PA, Friedman and Sheard raised the following questions. Which subsets of the Optional Axioms are consistent over the base theory? What are the proof-theoretic strengths of the consistent theories? The first question was answered completely by Friedman and Sheard; all subsets of the Optional Axioms were classified as either consistent or inconsistent giving rise to nine maximal consistent theories of truth.They also determined the proof-theoretic strength of two subsets of the Optional Axioms. The aim of this paper is to continue the work begun by Friedman and Sheard. We will establish the proof-theoretic strength of all the remaining seven theories and relate their arithmetic part to well-known theories ranging from PA to the theory of ${\Sigma^1_1}The first attempt at a systematic approach to axiomatic theories of truth was undertaken by Friedman and Sheard (Ann Pure
Appl Log 33:1–21, 1987). There twelve principles consisting of axioms, axiom schemata and rules of inference, each embodying
a reasonable property of truth were isolated for study. Working with a base theory of truth conservative over PA, Friedman
and Sheard raised the following questions. Which subsets of the Optional Axioms are consistent over the base theory? What
are the proof-theoretic strengths of the consistent theories? The first question was answered completely by Friedman and Sheard;
all subsets of the Optional Axioms were classified as either consistent or inconsistent giving rise to nine maximal consistent
theories of truth.They also determined the proof-theoretic strength of two subsets of the Optional Axioms. The aim of this
paper is to continue the work begun by Friedman and Sheard. We will establish the proof-theoretic strength of all the remaining
seven theories and relate their arithmetic part to well-known theories ranging from PA to the theory of S11{\Sigma^1_1} dependent choice. 相似文献
150.
Atomistic simulation techniques are used to investigate the defect properties of anatase TiO(2) and Li(x)TiO(2) both in the bulk and at the surfaces. Interatomic potential parameters are derived that reproduce the lattice constants of anatase, and the energies of bulk defects and surface structures are calculated. Reduction of anatase involving interstitial Ti is found to be the most favorable defect reaction in the bulk, with a lower energy than either Frenkel or Schottky reactions. The binding energies of selected defect clusters are also presented: for the Ti(3+)-Li(+) defect cluster, the binding energy is found to be approximately 0.5 eV, suggesting that intercalated Li ions stabilize conduction band electrons. The Li ion migration path is found to run between octahedral sites, with an activation energy of 0.45-0.65 eV for mole fractions of lithium in Li(x)TiO(2) of x < or = 0.1. The calculated surface energies are used to predict the crystal morphology, which is found to be a truncated bipyramid in which only the (101) and (001) surfaces are expressed, in accord with the available microscopy data. Calculations of defect energies at the (101) surface suggest that single Ti(3+) defects and neutral Ti(3+)-Li(+) pairs tend to segregate to the surface. 相似文献