Breakdown by a magnetic field of the superconducting fluctuations in the normal state: A simple phenomenological explanation

We first summarize our recent observations, through magnetization measurements in different low-Tc superconductors, of a rather sharp disappearance of the superconducting fluctuations in the normal state when the magnetic field approaches Hc2(0), the upper critical field extrapolated to T=0K. We propose that a crude phenomenological description of the observed effects may be obtained if the quantum limits associated with the uncertainty principle are introduced in the Gaussian-Ginzburg-Landau description of the fluctuation-induced magnetization.Comment: LaTeX, 8 pages, including 2 eps figures. Proceedings of SNS'04, Sitges, Spai

Comment on "High Field Studies of Superconducting Fluctuations in High-Tc Cuprates. Evidence for a Small Gap distinct from the Large Pseudogap"

By using high magnetic field data to estimate the background conductivity, Rullier-Albenque and coworkers have recently published [Phys.Rev.B 84, 014522 (2011)] experimental evidence that the in-plane paraconductivity in cuprates is almost independent of doping. In this Comment we also show that, in contrast with their claims, these useful data may be explained at a quantitative level in terms of the Gaussian-Ginzburg-Landau approach for layered superconductors, extended by Carballeira and coworkers to high reduced-temperatures by introducing a total-energy cutoff [Phys.Rev.B 63, 144515 (2001)]. When combined, these two conclusions further suggest that the paraconductivity in cuprates is conventional, i.e., associated with fluctuating superconducting pairs above the mean-field critical temperature.Comment: 9 pages, 1 figur

Anomalous precursor diamagnetism at low reduced magnetic fields and the role of Tc inhomogeneities in the superconductors Pb55In45 and underdoped La1.9Sr0.1CuO4

The magnetic field dependence of the magnetization was measured above the superconducting transition in a high-Tc underdoped cuprate La1.9Sr0.1CuO4 and in a low-Tc alloy (Pb55In45). Near the superconducting transition [typically for (T-Tc)/Tc<0.05] and under low applied magnetic field amplitudes [typically for H/Hc2(0)<0.01, where Hc2(0) is the corresponding upper critical field extrapolated to T=0 K] the magnetization of both samples presents a diamagnetic contribution much larger than the one predicted by the Gaussian Ginzburg-Landau (GGL) approach for superconducting fluctuations. These anomalies have been already observed in cuprate compounds by various groups and attributed to intrinsic effects associated with the own nature of these high-Tc superconductors. However, we will see here that our results in both high and low-Tc superconductors may be explained quantitatively, and consistently with the GGL behavior observed at higher fields, by just taking into account the presence in the samples of an uniform distribution of Tc inhomogeneities. These Tc inhomogeneities, which may be in turn associated with stoichiometric inhomogeneities, were estimated from independent measurements of the temperature dependence of the field-cooled magnetic susceptibility under low applied magnetic fields.Comment: 25 pages, including 6 figures and 1 table. Typos corrected. Compacte

Taxonomy and hierarchy of psychological abuse strategies in intimate partner relationships

This study focuses on the analysis from of a psychosocial perspective of the components of psychological abuse in intimate partner relationships. Following a review of studies on the subject, the main objective that emerged was the need for a new taxonomy of strategies of psychological abuse accompanied by the corresponding operational definitions. After the proposal of this new classification, a second objective emerged that consisted of submitting it for evaluation by a group of experts through a Delphi study, in which thirty-two experts from the academic and professional worlds participated. These experts were asked to assess the suitability of the system categories, and to grade quantitatively the severity of the impact made by each of the strategies on the global phenomenon of psychological abuse in couples. The results show that the experts ratified the new classification of strategies and their operational definitions, thus endorsing their content and construct validity. In addition, they classified the strategies based on their degree of severity; those of an emotional nature were considered the severest, followed by those related to the immediate context, with those of a cognitive type in third place, and lastly, the behavioural ones. Finally, we discuss the results, and their implications. Este estudio se centra en analizar los componentes del abuso psicológico en la violencia de pareja adulta y contra la mujer desde un enfoque psicosocial. Tras realizar una revisión de los estudios sobre el tema, se plantea como primer objetivo el proponer una nueva taxonomía de estrategias de abuso psicológico, acompañadas de sus respectivas definiciones operativas. A partir de esta nueva clasificación, se traza un segundo objetivo que se centra en someter esta clasificación al juicio de un grupo de expertos a través de un estudio Delphi, en el que han participado 32 expertos de los ámbitos académico - universitario y profesional. Estos expertos debían juzgar la adecuación del sistema de categorías, además de evaluar cuantitativamente la severidad que aporta cada una de las estrategias al fenómeno global del abuso psicológico en la pareja. Los resultados muestran que los expertos ratifican la nueva clasificación de estrategias y sus definiciones operativas, avalando así su validez de contenido y constructo. Además, jerarquizaron las estrategias de abuso, atribuyendo mayor severidad a las de tipo emocional, seguidas de las relacionadas con el contexto cercano, de las de tipo cognitivo y las de carácter conductual. Se discuten los resultados, sus limitaciones y las implicaciones que pueden derivarse de ellos