The entropy of a correlated system of nucleons

Realistic nucleon-nucleon interaction induce correlations to the nuclear many-body system which lead to a fragmentation of the single-particle strength over a wide range of energies and momenta. We address the question of how this fragmentation affects the thermodynamical properties of nuclear matter. In particular, we show that the entropy can be computed with the help of a spectral function which can be evaluated in terms of the self-energy obtained in the Self-Consistent Green's Function approach. Results for the density and temperature dependences of the entropy per particle for symmetric nuclear matter are presented and compared to the results of lowest order finite temperature Brueckner--Hartree--Fock calculations. The effects of correlations on the calculated entropy are small, if the appropriate quasi-particle approximation is used. The results demonstrate the thermodynamical consistency of the self-consistent T-matrix approximation for the evaluation of the Green's functions.Comment: REVTEX4 - 43 pages, 10 figures - Published versio

The entropy of a correlated system of nucleons

Realistic nucleon-nucleon interaction induce correlations to the nuclear many-body system which lead to a fragmentation of the single-particle strength over a wide range of energies and momenta. We address the question of how this fragmentation affects the thermodynamical properties of nuclear matter. In particular, we show that the entropy can be computed with the help of a spectral function which can be evaluated in terms of the self-energy obtained in the Self-Consistent Green's Function approach. Results for the density and temperature dependences of the entropy per particle for symmetric nuclear matter are presented and compared to the results of lowest order finite temperature Brueckner--Hartree--Fock calculations. The effects of correlations on the calculated entropy are small, if the appropriate quasi-particle approximation is used. The results demonstrate the thermodynamical consistency of the self-consistent T-matrix approximation for the evaluation of the Green's functions.Comment: REVTEX4 - 43 pages, 10 figures - Published versio

Centrolene savagei

Number of Pages: 11Geological SciencesIntegrative Biolog

Diversidad cultural y educación científica : una crítica epistemológica y ética

Este avance de investigación sobre las concepciones de profesores de ciencias acerca de la diversidad cultural (DC) en la enseñanza de las ciencias, se pregunta por las perspectivas epistemológicas que no la reconocen. El marco teórico se fundamenta en la idea de etnocentrismo epistemológico. La metodología es de tipo cualitativo y analiza 17 entrevistas, los resultados se ilustran con el caso de una profesora, dada su pertinencia e impacto. Se concluye, que aunque tiene una actitud crítica frente a la exclusión de la DC, sus perspectivas sobre la naturaleza cultural e histórica de la ciencia deben ser fortalecidas

Read it with Meaning: Aloud

Between 1910 and 1925 the emphasis in reading instruction in elementary and secondary schools switched dramatically from oral reading to silent reading. Emphasis on oral reading was almost totally neglected. Educators of the 1920s believed that silent reading was more efficient than oral reading in the areas of rate, comprehension, and convenience. As McCluskey (1942) explained, a theory was put forth that the faster one read, the more one understood. Speed, therefore, became thoroughly entrenched and oral reading with its slower ways was politely placed in solitary confinement (p. 15)

Correlations in Hot Asymmetric Nuclear Matter

The single-particle spectral functions in asymmetric nuclear matter are computed using the ladder approximation within the theory of finite temperature Green's functions. The internal energy and the momentum distributions of protons and neutrons are studied as a function of the density and the asymmetry of the system. The proton states are more strongly depleted when the asymmetry increases while the occupation of the neutron states is enhanced as compared to the symmetric case. The self-consistent Green's function approach leads to slightly smaller energies as compared to the Brueckner Hartree Fock approach. This effect increases with density and thereby modifies the saturation density and leads to smaller symmetry energies.Comment: 7 pages, 7 figure

Levy-Nearest-Neighbors Bak-Sneppen Model

We study a random neighbor version of the Bak-Sneppen model, where "nearest neighbors" are chosen according to a probability distribution decaying as a power-law of the distance from the active site, P(x) \sim |x-x_{ac }|^{-\omega}. All the exponents characterizing the self-organized critical state of this model depend on the exponent \omega. As \omega tends to 1 we recover the usual random nearest neighbor version of the model. The pattern of results obtained for a range of values of \omega is also compatible with the results of simulations of the original BS model in high dimensions. Moreover, our results suggest a critical dimension d_c=6 for the Bak-Sneppen model, in contrast with previous claims.Comment: To appear on Phys. Rev. E, Rapid Communication