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  • Consejo Superior de Investigaciones Científicas (CSIC)  (11)
  • American Institute of Physics (AIP)  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Generalization of the Darboux transform (2001)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 42 (2001), S. 966-975 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: This article presents a generalization of the standard Darboux transform applied to Sturm–Liouville differential equations. This is achieved with the aid of an ansatz as a particular solution for the Riccati relationship involved, which in turn led us to obtain its generalized Darboux solution that contains, as a particular case, the standard Darboux transform. The proposed generalized Darboux transform (GDT), applied to the quantum mechanical field, gives the opportunity to prove the existence of standard and generalized Darboux potentials that match with the so-called isospectral potentials. This is exemplified by obtaining, through the GDT, a set of standard and generalized Darboux potentials that form the partner of the one-dimensional harmonic oscillator model for any quantum principal number. The worked example indicates how the GDT can be used to obtain the isospectral potentials associated to any known specific potential. We consider also the application of our method as proposed to the theory of solitons in order to show why the GDT will be important in other fields of application where the standard Darboux transform is usually concerned. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1334904
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  • 2
    Electronic Resource
    Electronic Resource
    Electron nuclear dynamics of proton collisions with methane at 30 eV (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 6146-6155 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The reactive collisions of protons with methane molecules at 30 eV in the laboratory frame are studied with the electron nuclear dynamics (END). The results from this theoretical approach, which does not invoke the Born–Oppenheimer approximation and does not impose any constraints on the nuclear dynamics, are compared to the results from time-of-flight measurements. Total differential cross sections and integral cross sections as well as fragmentation ratios and energy loss spectra are discussed.© 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474343
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  • 3
    Electronic Resource
    Electronic Resource
    Hypervirial theorem and parameter differentiation: Closed formulation for harmonic oscillator integrals (1987)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 28 (1987), S. 1032-1035 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: A simple method has been developed to generate a closed formula for the calculation of matrix elements of arbitrary functions f(x) in the representation of the harmonic oscillator. The proposed algebraic procedure is based on the combined use of the hypervirial theorem with and without the second quantization formalism along with the parameter differentiation technique. The closed formula thus obtained is given in terms of a sum involving the jth derivative of f(x) evaluated at zero.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.527543
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  • 4
    Electronic Resource
    Electronic Resource
    Recurrence relations for two-center harmonic oscillator integrals (1986)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 27 (1986), S. 2966-2972 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: General recurrence relations for the calculation of two-center harmonic oscillator (HO) integrals are obtained by means of a hypervirial-like-theorem commutator algebra procedure, combined with a second quantization formalism. The method is based on a linear transformation between the creation and annihilation operators of two displaced HO with different frequencies. Ansbacher's recurrence relations for the calculation of Franck–Condon factors are obtained straightforwardly from the proposed general recurrence relations. The application to polynomial, exponential, and Gaussian operator integrals is shown and new recurrence relations are given. In all cases, the proposed recurrence relations reduce, as particular cases, to the corresponding formulas for the calculation of one-center integrals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.527277
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  • 5
    Electronic Resource
    Electronic Resource
    The generalization of the binomial theorem (1989)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 30 (1989), S. 393-397 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: As is well known, the binomial theorem is a classical mathematical relation that can be straightforwardly proved by induction or through a Taylor expansion, albeit it remains valid as long as [A,B]=0. In order to generalize such an important equation to cases where [A,B]≠0, an algebraic approach based on Cauchy's integral theorem in conjunction with the Baker–Campbell–Hausdorff series is presented that allows a partial extension of the binomial theorem when the commutator [A,B]=c, where c is a constant. Some useful applications of the new proposed generalized binomial formula, such as energy eigenvalues and matrix elements of power, exponential, Gaussian, and arbitrary f(xˆ) functions in the one-dimensional harmonic oscillator representation are given. The results here obtained prove to be consistent in comparison to other analytical methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.528457
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  • 6
    Electronic Resource
    Electronic Resource
    Two new potentials for the free particle model (1999)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 40 (1999), S. 5555-5564 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: In this work, is proposed a very simple method for obtaining the generalized potential associated with a known standard potential. The procedure is straightforward because it only uses two Ricatti-type relationships as enough condition to find a generalized potential; one particular equation is needed to identify the specific potential under study and one general Ricatti relationship is used to find the corresponding generalized potential. Moreover, the method is completely general due to the fact that an arbitrary potential has been considered in its development for which the procedure can also be used to find new potentials which could be needed in the modeling of important quantum interactions. The usefulness of the proposed approach, is shown with the treatment of the three- and one-dimensional potential for the free particle model. This work example leads to two new potentials whose Hamiltonians are isospectral when they are compared with the former Hamiltonian. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.533045
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  • 7
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    Agricultural activity shapes the communication and migration patterns in Senegal (2016)
    American Institute of Physics (AIP)
    In: Chaos
    Details
    Publication Date: 2016-06-08
    Description: The communication and migration patterns of a country are shaped by its socioeconomic processes. The economy of Senegal is predominantly rural, as agriculture employs over 70% of the labor force. In this paper, we use mobile phone records to explore the impact of agricultural activity on the communication and mobility patterns of the inhabitants of Senegal. We find two peaks of phone calls activity emerging during the growing season. Moreover, during the harvest period, we detect an increase in the migration flows throughout the country. However, religious holidays also shape the mobility patterns of the Senegalese people. Hence, in the light of our results, agricultural activity and religious holidays are the primary drivers of mobility inside the country.
    Print ISSN: 1054-1500
    Electronic ISSN: 1089-7682
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 8
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    Three-dimensional gyrokinetic simulation of the relaxation of a magnetized temperature filament (2015)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2015-10-08
    Description: An electromagnetic, 3D gyrokinetic particle code is used to study the relaxation of a magnetized electron temperature filament embedded in a large, uniform plasma of lower temperature. The study provides insight into the role played by unstable drift-Alfvén waves observed in a basic electron heat transport experiment [D. C. Pace et al ., Phys. Plasmas 15 , 122304 (2008)] in which anomalous cross-field transport has been documented. The simulation exhibits the early growth of temperature-gradient-driven, drift-Alfvén fluctuations that closely match the eigenmodes predicted by linear theory. At the onset of saturation, the unstable fluctuations display a spiral spatial pattern, similar to that observed in the laboratory, which causes the rearrangement of the temperature profile. After saturation of the linear instability, the system exhibits a markedly different behavior depending on the inclusion in the computation of modes without variation along the magnetic field, i.e., k z  = 0. In their absence, the initial filament evolves into a broadened temperature profile, self-consistent with undamped, finite amplitude drift-Alfvén waves. But the inclusion of k z  = 0 modes causes the destruction of the filament and damping of the drift-Alfvén modes leading to a final state consisting of undamped convective cells and multiple, smaller-scale filaments.
    Print ISSN: 1070-664X
    Electronic ISSN: 1089-7674
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 9
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    Una nueva especie de Agriarctos (Ailuropodinae, Ursidae, Carnivora) en la localidad de Nombrevilla 2 (Zaragoza, España) (2012)
    Consejo Superior de Investigaciones Científicas (CSIC)
    Details
    Publication Date: 2012-03-01
    Description: Una nueva especie de úrsido primitivo, Agriarctos beatrix procedente de la localidad de Nombrevilla 2 (Zaragoza, cuenca de Calatayud-Daroca) es descrita en este trabajo. Los nuevos fósiles de Nombrevilla 2 se relacionan estrechamente con Agriarctos depereti de la localidad de Soblay (Vallesiense superior, Francia), pero en la forma española los caracteres derivados compartidos son más primitivos. Agriarctos beatrix es la primera aparición conocida hasta el presente de un miembro de la subfamilia Ailuropodinae en el registro fossil.
    Print ISSN: 0367-0449
    Electronic ISSN: 1988-3250
    Topics: Geosciences
    Published by Consejo Superior de Investigaciones Científicas (CSIC)
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  • 10
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    El cambio de ideas acerca de la evolución y morfología functional de los félidos Machairodontinos (2012)
    Consejo Superior de Investigaciones Científicas (CSIC)
    Details
    Publication Date: 2012-03-01
    Description: Los félidos de dientes de sable, los macairodontinos, han ejercido una especial atracción entre los paleontólogos durante muchas décadas, no sólo por su espectacular morfología, sino también debido a que son un llamativo ejemplo de evolución convergente, probablemente ligada a una fuerte presión selectiva. En este trabajo suministramos una recopilación de los cambios de interpretación acerca de su anatomía functional y evolución, desde las primeras hipótesis en las que se proponía un ataque por apuñalamiento y un control pleitrópico del complejo morfológico macairodontino, hasta los actuales puntos de vista que favorecen un modelo de mordedura muy especializado y una evolución en mosaico de los carácteres anatómicos.
    Print ISSN: 0367-0449
    Electronic ISSN: 1988-3250
    Topics: Geosciences
    Published by Consejo Superior de Investigaciones Científicas (CSIC)
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