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Debates actuales en torno a las políticas del reconocimiento: constitución de los sujetos y cambio social
Ramaglia,Dante;
Estudios de filosof？-a pr？？ctica e historia de las ideas , 2010,
Abstract: the perspectives provided by the recognition theory to understand the transformations that have been happening in contemporary societies, have swiftly turned into a focus of discussion in social and political philosophy. especially there are examined some theoretical proposals which depart from the consideration of the anthropological sense of recognition, and its reinterpretation from the definition that it has in modern culture, in philosophers like rousseau and hegel, in order to give different keys of interpreting those social change processes which have been taking place till the present. one of the analyzed options is associated with the frankfurtian philosopher axel honneth, who has developed a set of thesis about the importance of mutual recognition in relation to the dynamics that mobilize social conflicts. besides the need to contrast this with other contemporary approaches, they are also reviewed some assumptions and scopes of the theory of recognition from a critical perspective that is contextualized within the framework of the transformations produced by globalization and the ongoing crisis of capitalist societies. from this point of view, it is interesting to inquire into the significance of alternative manifestations of social movements in their new forms of protest and claim of justice. in this respect, some guidelines concerning the policies of recognition are tested, as this discussion involves an evaluation of equality and difference as normative and guiding principles of the material and cultural changes occurring in today's world.
El pensamiento filosófico latinoamericano, del Caribe y "latino" (1300-2000): Historia, corrientes, temas y filósofos
Dante Ramaglia
Cuyo Anuario de Filosofía Argentina y Americana , 2010,
Abstract:
The spin-double refraction in two-dimensional electron gas
D. Bercioux,V. Marigliano Ramaglia
Physics , 2005, DOI: 10.1016/j.spmi.2004.12.009
Abstract: We briefly review the phenomenon of the spin-double refraction that originates at an interface separating a two-dimensional electron gas with Rashba spin-orbit coupling from a one without. We demonstrate how this phenomenon in semiconductor heterostructures can produce and control a spin-polarized current without ferromagnetic leads.
Different titanium surfaces modulate the bone phenotype of SaOS-2 osteoblast-like cells
L Postiglione,G Di Domenico,L Ramaglia,AE di Lauro
European Journal of Histochemistry , 2004, DOI: 10.4081/890
Abstract: Commercially pure titanium implants presenting a relatively smooth, machined surface or a roughened endosseous surface show a large percentage of clinical success. Surface properties of dental implants seem to affect bone cells response. Implant topography appears to modulate cell growth and differentiation of osteoblasts affecting the bone healing around the titanium implant. The aim of the present study was to examine the effects of 1cm diameter and 1mm thick titanium disks on cellular morphology, adhesion and bone phenotypic expression of human osteoblast-like cells, SaOS-2. SaOS-2 cells were cultured on commercially 1 cm pure titanium disks with three different surface roughness: smooth (S), sandblasted (SB) and titanium plasma sprayed (TPS). Differences in the cellular morphology were found when they were grown on the three different surfaces. An uniform monolayer of cells recovered the S surface, while clusters of multilayered irregularly shaped cells were distributed on the rough SB and TPS surfaces. The adhesion of SaOS-2 cells, as measured after 3h of culture, was not affected by surface roughness. ECM components such as Collagen I (CoI), Fibronectin (FN), Vitronectin (VN) and Tenascin (TN) were secreted and organized only on the SB and TPS surfaces while they remained into the cytoplasm on the S surfaces. Osteopontin and BSP-II were largely detected on the SB and TPS surfaces, while only minimal production was observed on the S ones. These data show that titanium surface roughness affects bone differentiation of osteoblast like-cells, SaOS-2, indicating that surface properties may be able to modulate the osteoblast phenotype. These observations also suggest that the bone healing response around dental implants can be affected by surface topography.
Rashba quantum wire: exact solution and ballistic transport
C. A. Perroni,D. Bercioux,V. M. Ramaglia,V. Cataudella
Physics , 2007, DOI: 10.1088/0953-8984/19/18/186227
Abstract: The effect of Rashba spin-orbit interaction in quantum wires with hard-wall boundaries is discussed. The exact wave function and eigenvalue equation are worked out pointing out the mixing between the spin and spatial parts. The spectral properties are also studied within the perturbation theory with respect to the strength of the spin-orbit interaction and diagonalization procedure. A comparison is done with the results of a simple model, the two-band model, that takes account only of the first two sub-bands of the wire. Finally, the transport properties within the ballistic regime are analytically calculated for the two-band model and through a tight-binding Green function for the entire system. Single and double interfaces separating regions with different strengths of spin-orbit interaction are analyzed injecting carriers into the first and the second sub-band. It is shown that in the case of a single interface the spin polarization in the Rashba region is different from zero, and in the case of two interfaces the spin polarization shows oscillations due to spin selective bound states.
Effects of electron coupling to intra- and inter-molecular vibrational modes on the transport properties of single crystal organic semiconductors
C. A. Perroni,V. Marigliano Ramaglia,V. Cataudella
Physics , 2011, DOI: 10.1103/PhysRevB.84.014303
Abstract: Electron coupling to intra- and inter-molecular vibrational modes is investigated in models appropriate to single crystal organic semiconductors, such as oligoacenes. Focus is on spectral and transport properties of these systems beyond perturbative approaches. The interplay between different couplings strongly affects the temperature band renormalization that is the result of a subtle equilibrium between opposite tendencies: band narrowing due to interaction with local modes, band widening due to electron coupling to non local modes. The model provides an accurate description of the mobility as function of temperature: indeed, it has the correct order of magnitude, at low temperatures, it scales as a power-law $T^{-\delta}$ with the exponent $\delta$ larger than unity, and, at high temperatures, shows an hopping behavior with a small activation energy.
Electronic transport within a quasi two-dimensional model for rubrene single-crystal field effect transistors
F. Gargiulo,C. A. Perroni,V. Marigliano Ramaglia,V. Cataudella
Physics , 2011, DOI: 10.1103/PhysRevB.84.245204
Abstract: Spectral and transport properties of the quasi two-dimensional adiabatic Su-Schrieffer-Heeger model are studied adjusting the parameters in order to model rubrene single-crystal field effect transistors with small but finite density of injected charge carriers. We show that, with increasing temperature $T$, the chemical potential moves into the tail of the density of states corresponding to localized states, but this is not enough to drive the system into an insulating state. The mobility along different crystallographic directions is calculated including vertex corrections which give rise to a transport lifetime one order of magnitude smaller than spectral lifetime of the states involved in the transport mechanism. With increasing temperature, the transport properties reach the Ioffe-Regel limit which is ascribed to less and less appreciable contribution of itinerant states to the conduction process. The model provides features of the mobility in close agreement with experiments: right order of magnitude, scaling as a power law $T^{-\gamma}$, with $\gamma$ close or larger than two, and correct anisotropy ratio between different in-plane directions. Due to a realistic high dimensional model, the results are not biased by uncontrolled approximations.
Probing nonlinear mechanical effects through electronic currents: the case of a nanomechanical resonator acting as electronic transistor
A. Nocera,C. A. Perroni,V. Marigliano Ramaglia,V. Cataudella
Physics , 2012, DOI: 10.1103/PhysRevB.86.035420
Abstract: We study a general model describing a self-detecting single electron transistor realized by a suspended carbon nanotube actuated by a nearby antenna. The main features of the device, recently observed in a number of experiments, are accurately reproduced. When the device is in a low current-carrying state, a peak in the current signals a mechanical resonance. On the contrary, a dip in the current is found in high current-carrying states. In the nonlinear vibration regime of the resonator, we are able to reproduce quantitatively the characteristic asymmetric shape of the current-frequency curves. We show that the nonlinear effects coming out at high values of the antenna amplitude are related to the effective nonlinear force induced by the electronic flow. The interplay between electronic and mechanical degrees of freedom is understood in terms of an unifying model including in an intrinsic way the nonlinear effects driven by the external probe.
Behavior of quantum entropies in polaronic systems
C. A. Perroni,V. Marigliano Ramaglia,V. Cataudella
Physics , 2010, DOI: 10.1103/PhysRevB.82.104303
Abstract: Quantum entropies and state distances are analyzed in polaronic systems with short range (Holstein model) and long range (Fr$\ddot{o}$hlich model) electron-phonon coupling. These quantities are extracted by a variational wave function which describes very accurately polaron systems with arbitrary size in all the relevant parameter regimes. With the use of quantum information tools, the crossover region from weak to strong coupling regime can be characterized with high precision. Then, the linear entropy is found to be very sensitive to the range of the electron-phonon coupling and the adiabatic ratio. Finally, the entanglement entropy is studied as a function of the system size pointing out that it not bounded, but scales as the logarithm of the size either for weak electron-phonon coupling or for short range interaction. This behavior is ascribed to the peculiar coupling induced by the single electron itinerant dynamics on the phonon subsystem.
Spectral, optical and transport properties of the adiabatic anisotropic Holstein model: Application to slightly doped organic semiconductors
C. A. Perroni,A. Nocera,V. Marigliano Ramaglia,V. Cataudella
Physics , 2011, DOI: 10.1103/PhysRevB.83.245107
Abstract: Spectral, optical and transport properties of an anisotropic three-dimensional Holstein model are studied within the adiabatic approximation. The parameter regime is appropriate for organic semiconductors used in single crystal based field effect transistors. Different approaches have been used to solve the model: self-consistent Born approximation valid for weak electron-phonon coupling, coherent potential approximation exact for infinite dimensions, and numerical diagonalization for finite lattices. With increasing temperature, the width of the spectral functions gets larger and larger making the approximation of quasi-particle less accurate. On the contrary, their peak positions are never strongly renormalized in comparison with the bare ones. As expected, the density of states is characterized by an exponential tail corresponding to localized states at low temperature. For weak electron-lattice coupling, the optical conductivity follows a Drude behavior, while, for intermediate electron-lattice coupling, a temperature dependent peak is present at low frequency. For high temperatures and low particle densities, the mobility always exhibits a power-law behavior as function of temperature. With decreasing the particle density, at low temperature, the mobility shows a transition from metallic to insulating behavior. Results are discussed in connection with available experimental data.
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