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1.
2.
Bjorn Fritzell 《Journal of voice》1992,6(2)
Inverse filtering is a noninvasive method of producing a glottogram thought to reflect the vibratory motions of the vocal fold. The flow glottogram provides information related to the type of phonation, the sound pressure level, the regularity of vocal fold vibrations, and to the presence or absence of vocal fold closure. Limited data, speech samples, filter tuning, and lack of unanimity on waveform display and interpretation have contributed to slow application of the techniques to the clinical population. The author argues the technique has utility in both diagnosis and treatment 相似文献
3.
We use agarose gel electrophoresis to characterize how the monovalent catioinic surfactant cetyltrimethylammonium bromide (CTAB) compacts double-stranded DNA, which is detected as a reduction in electrophoretic DNA velocity. The velocity reaches a plateau at a ratio R = 1.8 of CTAB to DNA-phosphate charges, i.e., above the neutralization point, and the complexes retain a net negative charge at least up to R = 200. Condensation experiments on a mixture of two DNA sizes show that the complexes formed contain only one condensed DNA molecule each. These CTAB-DNA globules were further characterized by time-resolved measurements of their velocity inside the gel, which showed that CTAB does not dissociate during the migration but possibly upon entry into the gel. Using the Ogston-model for electrophoresis of spherical particles, the measured in-gel velocity of the globule is quantitatively consistent with CTAB having two opposite effects, reduction of both the electrophoretic charge and DNA coil size. In the case of CTAB the two effects nearly cancel, which can explain why opposite velocity shifts (globule faster than uncomplexed DNA) have been observed with some catioinic condensation agents. Dissociation of the complexes by addition of anionic surfactants was also studied. The DNA release from the globule was complete at a mixing ratio between anionic and cationic surfactants equal to 1, in agreement with equilibrium studies. Circular DNA retained its supercoiling, and this demonstrates a lack of DNA nicking in the compaction-release cycle which is important in DNA transfection and purification applications. 相似文献
4.
I. Pacios B. Lindman A. Horta K. Thuresson C. Renamayor 《Colloid and polymer science》2002,280(6):517-525
The effect of a water-soluble uncharged polymer on the stability of the lamellar phase of the Aerosol OT (AOT)/water system is studied. The lamellar phase still exists when water is replaced by an aqueous solution of poly(N,N- dimethylacrylamide) (RgƼ᎒2 Å). Since the coil dimensions are (much) larger than the thickness of the water layers (dwᅣ Å), the polymer molecules do not enter the lamellar phase. Instead segregation in small domains occurs, and in equilibrium with the AOT-rich phase another separate phase containing the polymer is formed. The polymer-rich phase exerts an osmotic pressure that reduces the water content in the AOT-rich phase, and by compression the repeat distance is reduced. 相似文献
5.
Costa T Miguel Mda G Lindman B Schillén K Seixas de Melo JS 《The journal of physical chemistry. B》2005,109(23):11478-11492
Steady-state and time-resolved fluorescence studies were performed on aqueous solutions of poly(acrylic acid) hydrophobically modified with two very different levels of naphthalene (Np). It is demonstrated that unique information on association phenomena involving hydrophobe-modifed polymers can be obtained from an extended fluorescence study by using data for a less-modified polymer as a reference. For the more highly modified polymer, the presence of excited-state (as well as ground-state) dimers in addition to monomer emission due to locally excited naphthalene gives evidence for hydrophobic association between naphthalene groups. This association becomes, as expected, much less important at higher pH due to the electrostatic repulsion between different chain segments. However, it is noted that even at high pH there is a significant self-association. The coexistence of static and dynamic quenching phenomena of the Np monomer label was also revealed in the time-resolved fluorescence data. The data are compatible with the existence of two types of monomers and one excimer and suggest that the essential contribution to the monomer emission comes from isolated chromophores, whereas excimer formation arises from both a dynamic route (excited Np chromophores able to produce a dynamic excimer) and a static route (excitation of ground-state Np dimers). At room temperature, the dissociative reaction, excimer-to-monomer, can be neglected, and thus the rate constant for excimer formation and decay could be obtained with and without considering the influence of preformed dimers. Temperature has shown to induce different behavior in the polymer photophysics. In the case of the less-labeled polymer, the decays were found to be single-exponential with the fluorescence lifetime decreasing with increasing temperature. From the temperature dependence of the steady-state fluorescence data, the activation energy for excimer formation and the binding energy of the excimer were evaluated at different pH values, through the Stevens-Ban-type plots of the excimer-to-monomer intensity ratio. With the time-resolved data, measured in the temperature range of 5-60 degrees C, it was possible to extract the intrinsic activation energies for excimer formation. The thermodynamic driving force for the intrapolymeric association was found to be dependent on a balance between hydrophobic and electrostatic interactions, which are dependent on the pH, temperature, and hydrophobic content of the polymer. 相似文献
6.
The CD spectra of L-2-methylpyrrolidine, L-prolinol, and their N-methylated derivatives have been determined. As in the 2-substituted piperidines, N-methylation results in an inversion of the sign of the Cotton effects (CE). However, the sign of the long-wavelength CE does not follow the simple helicity rule found for 2-substituted piperidines, since the pyrrolidine ring is itself chiral and makes its own contributions to the observed CE's. The rotational contribution due to pyrrolidine ring chirality appears to be opposite in sign to and larger in magnitude than that due to the 2-substituent in both the secondary and the tertiary amines. 相似文献
7.
E. G. Coffman Jr. Bjorn Poonen Peter Winkler 《Probability Theory and Related Fields》1995,102(1):105-121
Summary Letn random intervalsI
1, ...,I
n be chosen by selecting endpoints independently from the uniform distribution on [0.1]. Apacking is a pairwise disjoint subset of the intervals; itswasted space is the Lebesgue measure of the points of [0,1] not covered by the packing. In any set of intervals the packing with least wasted space is computationally easy to find; but its expected wasted space in the random case is not obvious. We show that with high probability for largen, this best packing has wasted space
. It turns out that if the endpoints 0 and 1 are identified, so that the problem is now one of packing random arcs in a unit-circumference circle, then optimal wasted space is reduced toO(1/n). Interestingly, there is a striking difference between thesizes of the best packings: about logn intervals in the unit interval case, but usually only one or two arcs in the circle case. 相似文献
8.
Bjorn Poonen 《Journal of the American Mathematical Society》1996,9(3):783-812
Let be an algebraically closed field containing which is complete with respect to an absolute value . We prove that under suitable constraints on the coefficients, the series converges to a surjective, open, continuous -linear homomorphism whose kernel is locally compact. We characterize the locally compact sub--vector spaces of which occur as kernels of such series, and describe the extent to which determines the series. We develop a theory of Newton polygons for these series which lets us compute the Haar measure of the set of zeros of of a given valuation, given the valuations of the coefficients. The ``adjoint' series converges everywhere if and only if does, and in this case there is a natural bilinear pairing
which exhibits as the Pontryagin dual of . Many of these results extend to non-linear fractional power series. We apply these results to construct a Drinfeld module analogue of the Weil pairing, and to describe the topological module structure of the kernel of the adjoint exponential of a Drinfeld module.
9.
N. Kamenka M. Chorro H. Fabre B. Lindman J. Rouviere C. Cabos 《Colloid and polymer science》1979,257(7):757-767
Resumé Les propriétés physico-chimiques de solutions aqueuses de différents alkyl-p-benzènesulfonates de pureté contrôlée ont été déterminées par diverses méthodes: solubilité, viscosité, autodiffusions. Les micelles formées par len-octyl-p-benzènesulfonate de sodium (C8
SO3 Na) et len-dodécyl-p-benzènesul-fornate de sodium (C12
Na) sont globulaires dans tout le domaine de concetration exploité; les micelles (C8
SO3 Na + C12
SO3 Na) sont de taille proche de celles de C8
SO3 Na.La détermination du nombre de contre-ions liés aux micelles de C8
SO3 Na confirme cette structure.
Avec 6 figures et 7 tableaux
The Lund Institute of Technology, Lund (Suède).
Groupe de Dynamique des phases condensées, USTL. 相似文献
Summary Various methods, i. e. solubility, viscosity and self-diffusion have been employed to determine the physico chemical parameters of aqueous solutions of puren-alkyl-p-benzene-sulfonates. Micelles of sodiumn-octyl-p-benzene sulfonate (C8 SO3 Na) are of globular shape; mixed micelles formed by these compounds (C8 SO3 Na + C12 SO3 Na) show a very slight swelling compared with C8 S03 Na micelles.The degree of counter-ion association of C8 SO3 Na micelles is in good accordance with a globular shape of the micelles.
Zusammenfassung Löslichkeit, Viskosität und Selbst-Diffusion wurden benutzt, um physikalisch-chemische Parameter von wäßrigen Lösungen reinern-Alkyl-p-benzenesulfonate zu bestimmen. Mizellen von Natriumn-Oktylpbenzenesulfonar (C8 SO3 Na) haben eine globulare Form; Mischmizelle von C8 SO3 Na und C12 SO3 Na zeigen eine sehr geringe Quellung im Vergleich mit Mizellen von C8 SO3 Na.Der Grad von Gegenionenassoziation zu C8 SO3-Mizellen ist in guter Übereinstimmung mit einer globularen Form der Mizellen.
Avec 6 figures et 7 tableaux
The Lund Institute of Technology, Lund (Suède).
Groupe de Dynamique des phases condensées, USTL. 相似文献
10.