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21.
Most singers prefer to warm up their voices before performing. Although the subjective effect is often considerable, the underlying physiological effects are largely unknown. Because warm-up tends to increase blood flow in muscles, it seems likely that vocal warm-up might induce decreased viscosity in the vocal folds. According to the theory of vocal-fold vibration, such a decrease should lead to a lower phonation threshold pressure. In this investigation the effect of vocal warm-up on the phonation threshold pressure was examined in a group of male and female singers. The effect varied considerably between subjects, presumably because the vocal-fold viscosity was not a dominating factor for the phonation-threshold pressure. 相似文献
22.
Friis Helmer André Pedersen Janne Jettestuen Espen Helland Johan Olav Prodanović Maša 《Transport in Porous Media》2019,128(1):123-151
Transport in Porous Media - Multiphase flow simulations on imaged porous rock structures require numerical methods that are accurate and robust when applied on complex geometries. A key element in... 相似文献
23.
Hans Vanrompay Armand Bch Johan Verbeeck Sara Bals 《Particle & Particle Systems Characterization》2019,36(7)
One of the emerging challenges in the field of 3D characterization of nanoparticles by electron tomography is to avoid degradation and deformation of the samples during the acquisition of a tilt series. In order to reduce the required electron dose, various undersampling approaches have been proposed. These methods include lowering the number of 2D projection images, reducing the probe current during the acquisition, and scanning a smaller number of pixels in the 2D images. A comparison is made between these approaches based on tilt series acquired for a gold nanoparticle. 相似文献
24.
Journal of Solid State Electrochemistry - 相似文献
25.
Kalina Mambourg Laurie Bodart Nikolay Tumanov Steve Lanners Johan Wouters 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(3):205-211
The condensation reaction of 2‐mercapto‐3‐methoxybenzaldehyde with 3‐aminopyridine afforded an unexpected N‐alkylated [1,5]dithiocine instead of the N‐salicylideneaniline. The proposed mechanism for this condensation involves a strong intramolecular hydrogen bond between the thiol and the amine groups, leading to a second condensation. The corresponding product, i.e. 4,10‐dimethoxy‐13‐(pyridin‐3‐yl)‐6H,12H‐6,12‐epiminodibenzo[b,f][1,5]dithiocine methanol 0.463‐solvate, C21H18N2O2S2·0.463CH3OH, was characterized by single‐crystal X‐ray diffraction analysis. The supramolecular structure shows π–π stacking and S…S interactions in the crystal packing. Within the asymmetric unit, two geometries of the N atom are observed. Although a planar geometry should be expected, a pyramidal one is observed due to the crystal packing. The presence of the two geometries was further supported by density functional theory (DFT) calculations that show an electronic energy difference of less than 2 kJ mol?1 between the two conformers. 相似文献
26.
Johan Sundberg 《Journal of voice》1990,4(2)
Research on singers' breathing, phonation and articulation patterns during singing is reviewed and comparisons are made with typical speech patterns. It is found that singers' and nonsingers' use of the voice differ in several respects. The reasons for these differences are discussed and explanations are proposed referring to the special demands raised on singers with respect to economization of vocal effort and flexibility of phonation. 相似文献
27.
Johan Tykesson 《Statistics & probability letters》2011,81(8):1256-1259
In Calka et al. (2009), the decay of the probability of reaching distance at least r in some direction from a given point without hitting any ball, in the Poisson Boolean model of continuum percolation, was studied. The methods used in Calka et al. (2009) include coverage techniques, and the most precise results were obtained in dimension 2. In this note, we strengthen some of the results obtained in Calka et al. (2009) to dimension 3 and higher and at the same time extend them to more general random sets. 相似文献
28.
Phonation threshold pressure has been defined as the minimum subglottalpressure to generate phonation. Previous research has indicated that children may habitually employ higher subglottal pressures than adults. In the present investigation sound pressure level (SPL) and subglottal pressures at different pitch levels were measured at and above phonation threshold in nine children. Phonation threshold values were scattered in reasonable agreement with Titzes' prediction, although a discrepancy was noted regarding the frequency dependence in some voices. At normal conversational loudness and loudest level of phonation the children's PS values were between two to four and four to eight times the predicted threshold values, respectively. At normal conversational loudness and habitual pitch subglottal pressures were lower than those previously observed for children, but similar to those found for female adults. The SPL in softest and loudest phonation were somewhat lower as compared to previous phonetogram data for children and for female adults. At normal loudness and habitual pitch the SPL values were similar to those of female adults. For a doubling of Ps mean SPL increased by 10.5 dB on the average. 相似文献
29.
The objective of this paper is to introduce a general scheme for the construction of interpolatory approximation formulas and compactly supported wavelets by using spline functions with arbitrary (nonuniform) knots. Both construction procedures are based on certain ``optimally local' interpolatory fundamental spline functions which are not required to possess any approximation property.
30.