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81.
Jean Dolbeault Maria J. Esteban Eric Séré 《Calculus of Variations and Partial Differential Equations》2000,10(4):321-347
In this paper we give two different variational characterizations for the eigenvalues of H+V where H denotes the free Dirac operator and V is a scalar potential. The first one is a min-max involving a Rayleigh quotient. The second one consists in minimizing an
appropriate nonlinear functional. Both methods can be applied to potentials which have singularities as strong as the Coulomb
potential.
Received June 5, 1998 / Accepted June 11, 1999 相似文献
82.
83.
Díaz Mario G. Andrada Matías F. Vega-Hissi Esteban G. Martinez Juan C. Garro 《Structural chemistry》2019,30(1):237-245
Structural Chemistry - An in silico analysis of the oxidation mechanism of allyl methyl disulfide (AMDS) by hydroxyl radical was achieved at DFT level using B3LYP, CAM-B3LYP, M06-2X, and BMK... 相似文献
84.
Esteban R. Bornancini Ruben A. Alonso Roberto A. Rossi 《Journal of organometallic chemistry》1984,270(2):177-183
The reactions of elemental phosphorus, arsenic and antimony with sodium metal in liquid ammonia form “M?1“ species that react with haloarenes under irradiation to form symmetrical triaryl derivatives of these metals by the SRN1 mechanism in fair to good yields. Further reaction with sodium metal gives a derivative nucleophile (diarylphosphide and diarylarsenide ions) that reacts with another haloarene under irradiation to form unsymmetrical phosphines and arsines. 相似文献
85.
The anodic processes which occur at the mercury electrode in 2-mercaptoethanol solutions are studied by various polarographic techniques (d.c., a.c. and differential pulse), controlled-potential coulometry, cyclic voltammetry and differential capacity curves. Two steps are distinguished in the process: a one-electron charge transfer and a dismutation step leading to the formation of a mercury(II) mercaptide. The final product is isolated and analyzed. Differential-pulse polarography can be used to determine ?10?4 M 2-mercaptoethanol with a limit of M. 相似文献
86.
87.
Simple turbulent diffusive models are proposed as conceptual tools for exploring scenarios involving mixing of stratified flows. Applications include the dynamics of the ocean's top mixed layer, shear instability, breaking internal waves, and turbulent stirring of sharp interfaces. A novel measure of mixing is developed, based on arguments from statistical physics. It is shown that, under turbulent diffusion, this measure grows, and that there are strong indications that, under stirring, flows tend to settle down at a maximum of this measure, subject to global dynamical constraints. © 2004 Wiley Periodicals, Inc. 相似文献
88.
The constraints imposed by the requirement that the scalar potential of supersymmetric theories does not have unbounded directions and charge or color breaking minima deeper than the usual electroweak breaking minimum (EWM) are significantly relaxed if one just allows for a metastable EWM but with a sufficiently long lifetime. For this to be acceptable one needs however to explain how the vacuum state reaches this metastable configuration in the first place. We discuss the implications for this issue of the inflation induced scalar masses, of the supersymmetry breaking effects generated during the preheating stage as well as of the thermal corrections to the scalar potential which appear after reheating. We show that their combined effects may efficiently drive the scalar fields to the origin, allowing them to then evolve naturally towards the EWM. 相似文献
89.
Javier Gamboa Félix Javier Jiménez-Jiménez Alberto Nieto Jose Montojo Miguel Ortí-Pareja José Antonio Molina Esteban García-Albea Ignacio Cobeta 《Journal of voice》1997,11(3):314-320
To quantify several acoustic features of the voice in patients withParkinson's disease (PD), 41 patients and 28 age and sex-matched controls were studied. PD severity was assessed with the Unified PD Rating Scale (UPDRS) and the Hoehn and Yahr staging. The Computerized Speech Lab 4300 program (Kay Elemetrics) was used. Two seconds of a sustained /a/ and a sentence were captured with a microphone and laryngograph equipment. Measures included fundamental frequency (FO), frequency perturbation (fitter), intensity perturbation (shimmer), and harmonic/noise ratio (H/N) of the vowel /a/, and frequency and intensity variability of a sentence, phonational range, dynamic range at the natural frequency, maximum phonational time and s/z ratio. All subjects underwent indirect laryngoscopy and/or laryngeal fibroscopy. When compared with controls, PD patients showed higher jitter, lower H/N ratio, lower frequency and intensity variability of the sentence, and lower phonational range and reported a higher frequency of the presence of low voice-intensity, monopitch, voice arrests, and struggle. These features seem to be unaffected by the duration and severity of the disease. 相似文献
90.
Esteban Gómez Gonzáles 《Mathematische Annalen》1997,307(2):341-342