Quantum Interference of Coulomb Interaction and Disorder: Phase Shift of Friedel Oscillations and an Instability of the Fermi Sea

We investigate the influence of interference between Coulomb interaction and impurity scattering on the static electronic response $\chi (0,q)$ in disordered metals to leading order in the effective Coulomb interaction. When the transport relaxation time $\tau _{tr}$ is much shorter than the quasiparticle life time, we find a \mbox{sgn}(2p_F-q)/\sqrt{|2p_F-q|} divergence of the polarization function at the Fermi surface ($q=2p_F$). It causes a phase shift of the Friedel oscillations as well as an enhancement of their amplitude. Our results are consistent with experiments and may be relevant for understanding the stability of the amorphous state of certain alloys against crystallization.Comment: 11 pages, 4 PostScript figures appended as a self-extracting tar archive; includes output instruction

El prudencialismo táctico de Baltasar Gracián

Nos quejamos del poco valor humano y ético de muchos políticos de nuestro tiempo, pero no es difícil encontrar antecedentes del daño que puede hacer al bien común no comprender la misión de servicio a los demás que tienen tanto la vida política como cualquier puesto de dirección en las organizaciones humanas

La educación política en la antigüedad clásica griega

En la Antigüedad clásica la participación política era considerada de la máxima importancia y definitoria del hombre libre; ser hombre era ser ciudadano. Esto implicaba a su vez la necesidad e importancia determinante de una formación orientada en dos dimensiones: participación ciudadana responsable y preparación para gobernar competentemente. Los principales filósofos políticos de entonces han tratado profunda y muy acertadamente este asunto; tanto es así, que muchos especialistas contemporáneos afirman con pesimismo: «hoy día la única novedad son los clásicos», también porque abordaron temas de gran actualidad para hoy avant la lettre. Incluso un apretado resumen, como se ofrece en este artículo, acerca del modo que abordaron esta educación política los principales autores griegos de ese período, puede ayudar a exhumar interesantes ideas que son como un rico filón de inspiración para programas hodiernos de formación política inspirados en los clásicos.Political participation in the ancient Greek society was considered of the outmost importance, defining the free man: to be man was to be a citizen. This fact emphasized the need and importance of a formation oriented in two dimensions: responsible citizenship participation and preparation for government. The main Greek political philosophers dealt with these topics in depth and very rightly up to the extent that many contemporary specialists state with pessimism: «nowadays, the only novelty are the classics» also because they analyzed topics of outmost current importance. Even a short abstract – as the one in the present paper – about political education by the most important Greek authors in the classic period, may help to extract interesting ideas to inspire the modern programs of political formation based on the classical authors

El buen gobernante en la antigüedad clásica. Indagación de un enfoque sapiencial en Plutarco [Crónica]

Texto leído en la defensa de la tesis doctoral realizada en la Facultad Eclesiástica de Filosofía de la Universidad de Navarra, el día 11 de febrero de 2011. Dirigió la tesis el Prof. Rafael Alvira. El tribunal estuvo compuesto por los profesores: José Ángel García Cuadrado (presidente), Ángel Luis González, Rafael Alvira, Kurt Spang, Javier Vergara (secretario)

Barriers and Facilitators of Safe Communication in Obstetrics: Results from Qualitative Interviews with Physicians, Midwives and Nurses.

Patient safety is an important objective in health care. Preventable adverse events (pAEs) as the counterpart to patient safety are harmful incidents that fell behind health care standards and have led to temporary or permanent harm or death. As safe communication and mutual understanding are of crucial importance for providing a high quality of care under everyday conditions, we aimed to identify barriers and facilitators that impact safe communication in obstetrics from the subjective perspective of health care workers. A qualitative study with 20 semi-structured interviews at two university hospitals in Germany was conducted to explore everyday perceptions from a subjective perspective (subjective theories). Physicians, midwives, and nurses in a wide span of professional experience and positions were enrolled. We identified a structural area of conflict at the professional interface between midwives and physicians. Mandatory interprofessional meetings, acceptance of subjective mistakes, mutual understanding, and debriefings of conflict situations are reported to improve collaboration. Additionally, emergency trainings, trainings in precise communication, and handovers are proposed to reduce risks for pAEs. Furthermore, the participants reported time-constraints and understaffing as a huge burden that hinders safe communication. Concluding, safety culture and organizational management are closely entwined and strategies should address various levels of which communication trainings are promising

Adaptive Optics Imaging of a Massive Galaxy Associated with a Metal-rich Absorber

The damped and sub-damped Lyman-alpha absorption line systems in quasar spectra are believed to be produced by intervening galaxies. However, the connection of quasar absorbers to galaxies is not well-understood, since attempts to image the absorbing galaxies have often failed. While most DLAs appear to be metal-poor, a population of metal-rich absorbers, mostly sub-DLAs, has been discovered in recent studies. Here we report high-resolution K-band imaging with the Keck Laser Guide Star Adaptive Optics (LGSAO) system of the field of quasar SDSSJ1323-0021 in search of the galaxy producing the z = 0.72 sub-DLA absorber. With a metallicity of 2-4 times the solar level, this absorber is of the most metal-rich systems found to date. Our data show a large bright galaxy with an angular separation of only 1.25" from the quasar, well-resolved from the quasar at the high resolution of our data. The galaxy has a magnitude of K = 17.6-17.9, which corresponds to a luminosity of ~ 3-6 L*. Morphologically, the galaxy is fit with a model with an effective radius, enclosing half the total light, of R_e = 4 kpc and a bulge-to-total ratio of 0.4-1.0, indicating a substantial bulge stellar population. Based on the mass-metallicity relation of nearby galaxies, the absorber galaxy appears to have a stellar mass > 10^{11} M_sun. Given the small impact parameter, this massive galaxy appears to be responsible for the metal-rich sub-DLA. The absorber galaxy is consistent with the metallicity-luminosity relation observed for nearby galaxies, but is near the upper end of metallicity. Our study marks the first application of LGSAO for study of structure of galaxies producing distant quasar absorbers. Finally, this study offers the first example of a massive galaxy with a substantial bulge producing a metal-rich absorber.Comment: 17 pages, 4 figures, 1 table; Accepted for publication in The Astronomical Journa

Nonequilibrium coupled Brownian phase oscillators

A model of globally coupled phase oscillators under equilibrium (driven by Gaussian white noise) and nonequilibrium (driven by symmetric dichotomic fluctuations) is studied. For the equilibrium system, the mean-field state equation takes a simple form and the stability of its solution is examined in the full space of order parameters. For the nonequilbrium system, various asymptotic regimes are obtained in a closed analytical form. In a general case, the corresponding master equations are solved numerically. Moreover, the Monte-Carlo simulations of the coupled set of Langevin equations of motion is performed. The phase diagram of the nonequilibrium system is presented. For the long time limit, we have found four regimes. Three of them can be obtained from the mean-field theory. One of them, the oscillating regime, cannot be predicted by the mean-field method and has been detected in the Monte-Carlo numerical experiments.Comment: 9 pages 8 figure

Mesoscopic Aharonov-Bohm oscillations in metallic rings

We study the amplitude of mesoscopic Aharonov-Bohm oscillations in quasi-one-dimensional (Q1D) diffusive rings. We consider first the low-temperature limit of a fully coherent sample. The variance of oscillation harmonics is calculated as a function of the length of the leads attaching the ring to reservoirs. We further analyze the regime of relatively high temperatures, when the dephasing due to electron-electron interaction suppresses substantially the oscillations. We show that the dephasing length L_phi^AB governing the damping factor exp(-2pi R /L_phi^AB) of the oscillations is parametrically different from the common dephasing length for the Q1D geometry. This is due to the fact that the dephasing is governed by energy transfers determined by the ring circumference 2pi R, making L_phi^AB R-dependent.Comment: 16 pages, 4 figures, to appear in proceedings of NATO/Euresco Conference "Fundamental Problems of Mesoscopic Physics: Interactions and Decoherence", Granada (Spain), September 200