871 research outputs found

    Para una noción de genealogía: bases teóricas y nuevos lineamientos para la praxis genealógica investigativa

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    Este artículo establece las bases teóricas desde las cuales es posible proyectar investigaciones futuras en torno a la historia del poder político en la que se relaciona el campo disciplinar del derecho con el campo disciplinar educacional chilenos. En este sentido, se parte proponiendo, desde una perspectiva post-estructuralista, tres conceptos fundamentales para el tratamiento del asunto: genealogía como modalidad específica del saber historiográfico; ley como determinación formal de los modos de dominación de una formación social; poder político como ejercicio histórico de los modos de dominación en las luchas estratégicas sociales. El texto concluye presentando los nuevos lineamientos metodológicos desde los que se repiensa la praxis genealógica como quehacer investigativo

    Materialismo y genealogía: una reflexión en torno al poder y al sistema escolar chileno

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    Esta reflexión tiene por objetivo determinar las directrices del estudio en torno al poder tanto desde el materialismo histórico, como desde la investigación genealógica foucaultiana,y su posible aplicación para el desarrollo de un estudio social sobre el SE (sistema escolar) como aparato de reproducción de la formación social chilena. Para lograr este propósito, se despliega un análisis de los conceptos fundamentales utilizados en la problematización en torno al poder que han desarrollado las dos perspectivas teóricas arriba enunciadas, seguido de una reflexión respecto de la aplicaciónde estos conceptos sobre el SE chileno. El resultado de este estudio es presentar una reflexión crítica en torno al poder, que sirva de base para una posterior investigación empírica del SE chileno en cuanto aparato de reproducción social

    Footprints in the sand: What can globular clusters tell us about NGC 4753 past?

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    NGC 4753 is a bright (M_V approx -22.3) lenticular galaxy. It is a very interesting target to test different theories of formation of lenticular galaxies, due to its low-density environment and complex structure. We perform the first comprehensive study of NGC 4753 globular cluster system (GCS), using Gemini/GMOS and CTIO/MosaicII images. Our results indicate a rather poor GCS of approx 1000 members. Its azimuthal distribution follows the shape of the galaxy bulge. The GC colour distribution is peculiar, presenting an intermediate subpopulation in addition to blue and red ones. This intermediate subgroup can be explained by a single stellar population with an age of 1.5-3 Gyr and 0.5-1 Z_o. The GC specific frequency S_N = 1.3+/-0.15 is surprisingly low for a galaxy of its class. The GC luminosity function (GCLF) is also peculiar, with an excess of bright GCs compared to the expected gaussian distribution. The underlying galaxy body has significant substructure, with remnants of spiral arms, dust filaments, and isophote twisting. This, and the fact that NGC 4753 hosted two type Ia SNe, support the possibility that the intermediate GC subpopulation may have originated during a recent merger, 1-3 Gyr ago.Comment: 10 pages, 10 figures, accepted on MNRA

    Transfer to the continuum calculations of quasifree (p,pn) and (p,2p) reactions

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    Nucleon removal (p, pn) and (p, 2p) reactions at intermediate energies have gained renewed attention in recent years as a tool to extract information from exotic nuclei. The information obtained from these experiments is expected to be sensitive to deeper portions of the wave function of the removed nucleon than knockout reactions with heavier targets. In this contribution, we present calculations for (p, 2p) and (p, pn) reactions performed within the so-called transfer to the continuum method (TR*). Results for stable and unstable nuclei are presented, and compared with experimental data, when availabl

    Influence of target deformation and deuteron breakup in ( d , p ) transfer reactions

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    Background: The effect of core excitations in transfer reactions of the form A ( d , p ) B has been reexamined by some recent works by using the Faddeev–Alt–Grassberger–Sandhas reaction formalism. The effect was found to affect significantly the calculated cross sections and to depend strongly and nonlinearly on the incident deuteron energy. Purpose: Our goal is to investigate these effects within a coupled-channel formulation of the scattering problem which, in addition to being computationally less demanding than the Faddeev counterpart, may help shed some light onto the physical interpretation of the cited effects. Method: We use an extended version of the continuum-discretized coupled-channel (CDCC) method with explicit inclusion of target excitations within a coupled-channel Born approximation (CDCC-BA) formulation of the transfer transition amplitude. We compare the calculated transfer cross sections with those obtained with an analogous calculation omitting the effect of target excitation. We consider also an adiabatic coupled-channel (ACC) method. Our working example is the 10 Be ( d , p ) 11 Be reaction. Results: We find that the two considered methods (CDCC-BA and ACC) reproduce fairly well the reported energy dependence of the core excitation effect. The main deviation from the pure three-body model calculation (i.e., omitting core excitations) is found to mostly originate from the destructive interference of the direct one-step transfer and the two-step transfer following target excitation. Conclusions: The proposed method; namely, the combination of the CDCC method and the CCBA formalism, provides a useful and accurate tool to analyze transfer reactions including explicitly, when needed, the effect of target excitations and projectile breakup. The method could be useful for other transfer reactions induced by weakly bound projectiles, including halo nuclei.Ministerio de Economía y Competitividad de España y Fondos FEDER. FIS2014-53448-C2-1-PPrograma Horizonte 2020 de la Unión Europea. 65400

    Interplay of projectile breakup and target excitation in reactions induced by weakly bound nuclei

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    Reactions involving weakly bound nuclei require formalisms able to deal with continuum states. The majority of these formalisms struggle to treat collective excitations of the systems involved. For continuumdiscretized coupled channels (CDCC), extensions to include target excitation have been developed but have only been applied to a small number of cases.Junta de Andalucía FQM160 P07-FQM-02894Ministerio de Economía y Competitividad FIS2014-53448-C2-1-

    Influence of target deformation and deuteron breakup in ( d , p ) transfer reactions

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    Background: The effect of core excitations in transfer reactions of the form A ( d , p ) B has been reexamined by some recent works by using the Faddeev–Alt–Grassberger–Sandhas reaction formalism. The effect was found to affect significantly the calculated cross sections and to depend strongly and nonlinearly on the incident deuteron energy. Purpose: Our goal is to investigate these effects within a coupled-channel formulation of the scattering problem which, in addition to being computationally less demanding than the Faddeev counterpart, may help shed some light onto the physical interpretation of the cited effects. Method: We use an extended version of the continuum-discretized coupled-channel (CDCC) method with explicit inclusion of target excitations within a coupled-channel Born approximation (CDCC-BA) formulation of the transfer transition amplitude. We compare the calculated transfer cross sections with those obtained with an analogous calculation omitting the effect of target excitation. We consider also an adiabatic coupled-channel (ACC) method. Our working example is the 10 Be ( d , p ) 11 Be reaction. Results: We find that the two considered methods (CDCC-BA and ACC) reproduce fairly well the reported energy dependence of the core excitation effect. The main deviation from the pure three-body model calculation (i.e., omitting core excitations) is found to mostly originate from the destructive interference of the direct one-step transfer and the two-step transfer following target excitation. Conclusions: The proposed method; namely, the combination of the CDCC method and the CCBA formalism, provides a useful and accurate tool to analyze transfer reactions including explicitly, when needed, the effect of target excitations and projectile breakup. The method could be useful for other transfer reactions induced by weakly bound projectiles, including halo nuclei.Ministerio de Economía y Competitividad de España y Fondos FEDER. FIS2014-53448-C2-1-PPrograma Horizonte 2020 de la Unión Europea. 65400

    Core excitation effects in halo nuclei using a transformed oscillator basis

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    A recent generalization of the Transformed Harmonic Oscillator basis, intended to consider core excitations in the structure of one nucleon halo nuclei, is applied to the break up of 11Be. The reaction studied is 11Be+208Pb at 69 MeV/nucleon. The experimental set up is designed to ensure pure dipole Coulomb excitations. Making use of the Equivalent Photon Method and the electromagnetic transition probabilities obtained with the transformed oscillator basis, a relevant contribution of the quadrupole excitations of the core is found. The inclusion of core excitations is, therefore, necessary for the correct extraction of the dipole electromagnetic transition probability of halo nuclei.Ministerio de Ciencia e Innovación FIS2011-28738-c02-01, FPA2009- 07653, FPA2009-08848, CSD2007-00042Junta de Andalucía FQM160, P07-FQM-0289

    Stabilization method in two-body systems with core excitations

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    The validity of the stabilization method in core+valence systems including the possibility of exciting the core is studied. A pseudostate method, based on the transformed harmonic oscillator basis, is extended to include the core degrees of freedom. The method is applied to the case of 11Be structure considering the 0+ ground state and the 2+ first excited state of the 10Be core. The stabilization method is defined in terms of one parameter that can be chosen either discrete or continuous. In the application to 11Be, both cases are analyzed.Ministerio de Ciencia e Innovación FIS2011-28738-c02-01, FPA2009-07653, FPA2009-08848, CSD2007-00042Junta de Andalucía FQM160, P07-FQM-0289
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