Bose-Einstein Condensation in a Constant Magnetic Field

We discuss the occurrence of Bose-Einstein condensation in systems of noninteracting charged particles in three in one dimensions and in presence of an external magnetic field. In the one dimensional, as well as in the magnetic field cases, although not a critical temperature, a characteristic temperature can be found, corresponding to the case in which the ground state density becomes a macroscopic fraction of the total density. The case of relativistic charged scalar and vector particles is studied. The results obtainedgive support to the existence of superconductivity in extremely strong magnetic fields, and leads to the prediction of superconductive-ferromagnetic behavior in the vector field case, which might be of interest in condensed matter as well as in cosmology. Some features of the magnetization in the early universe are conjectured.Comment: 20 pages, 2 GIF figure

Performance metrics for characterization of a seizure detection algorithm for offline and online use

Purpose: To select appropriate previously reported performance metrics to evaluate a new seizure detection algorithm for offline and online analysis, and thus quantify any performance variation between these metrics. Methods: Traditional offline algorithms mark out any EEG section (epoch) of a seizure (event), so that neurologists only analyze the detected and adjacent sections. Thus, offline algorithms could be evaluated using number of correctly detected events, or event-based sensitivity (SEVENT), and epoch-based specificity (percentage of incorrectly detected background epochs). In contrast, online seizure detection (especially, data selection) algorithms select for transmission only the detected EEG sections and hence need to detect the entire duration of a seizure. Thus, online algorithms could be evaluated using percentage of correctly detected seizure duration, or epoch-based sensitivity (SEPOCH), and epoch-based specificity. Here, a new seizure detection algorithm is evaluated using the selected performance metrics for epoch duration ranging from 1s to 60s. Results: For 1s epochs, the area under the event-based sensitivity-specificity curve was 0.95 whilst SEPOCH achieves 0.81. This difference is not surprising, as intuitively, detecting any epoch within a seizure is easier than detecting every epoch - especially as seizures evolve over time. For longer epochs of 30s or 60s, SEVENT falls to 0.84 and 0.82 respectively and SEPOCH reduces to 0.76. Here, decreased SEVENT shows that fewer seizures are detected, possibly due to easy-to-detect short seizure sections being masked by surrounding EEG. However, detecting one long epoch constitutes a larger percentage of a seizure than a shorter one and thus SEPOCH does not decrease proportionately. Conclusions: Traditional offline and online seizure detection algorithms require different metrics to effectively evaluate their performance for their respective applications. Using such metrics, it has been shown that a decrease in performance may be expected when an offline seizure detection algorithm (especially with short epoch duration) is used for online analysis.Accepted versio

The credibility of the Venezuela crawling-band system

This paper studies the credibility of the Venezuela crawling-band exchange rate regime during the period July, 1996-February, 2002. We show that, introducing some modifications, the credibility analysis widely applied to target zone regimes can also be used in studying the credibility of crawling- band regimes. In analyzing the credibility of the Venezuela crawling band, first we use the so-called simple credibility tests developed by Svensson (1991). Additionally, we estimate the expected rate of realignment using the drift- adjustment method. Both the credibility tests and the drift-adjustment method give similar results, showing that the crawling-band system was highly credible during the period.crawling band exchange rate system, credibility, realignments

Catherine of Siena’s crusade letters: Spirituality and political context

Catherine of Siena has been credited with original views regarding the crusade as political policy and with influencing Gregory XI to carry this out. In this article, I argued that while Catherine of Siena did not succeed in furthering the crusade – nor did she initiate this policy – her crusade correspondence leaves us a legacy that reveals significant aspects of her spirituality. Over 40 letters to ecclesiastical authorities, Kings, Queens, leaders of city states, knights and her own followers reveal a religious intent, although addressing a policy with both religious and political consequences. The latter were important to Catherine because she considered political-cultural context vital for salvation and transformation; she advocated for the crusade because she considered that the crusade pilgrimage and holy war to recover the Holy Land would be critical for the salvation of many. Her epistles further witness to the prophetic, missionary nature of Catherine’s spirituality, and we see how she crafted her own version of crusade spirituality out of the wisdom on transformation learned through her union with God, fused with early Christian martyr spirituality and early crusade spirituality preached in medieval Europe. This thematisation of Catherine’s crusade letters is based on textual analysis of all crusade related letters in the 2002 critical text, on the most complete dating of Catherine’s letters (finished in 2008); and in dialogue with literary and other historical advances, making it an innovative study. Contribution: Catherine of Siena’s crusade letters reveal significant aspects of her spirituality rather than contributions to crusade politics. The letters evidence her prophetic-missionary spirituality and her conviction that socio-political context is significant for a journey of transformation; as well, this analysis details the importance of early Christian martyr spirituality for Catherine’s crusade spirituality

Vortex-glass transition in superconducting Nb/Cu superlattices

Nb/Cu superconducting superlattices have been fabricated by dc magnetron sputtering. This system shows a vortex glass transition with critical exponents similar to high temperatures superconductors exponents. The transition dymensionality is governed by the superconducting coupling regime. The vortex glass transition shows a pure two dimensional behavior in decoupled superlattices and a quasi-two dimensional behavior in the superlattice coupling regime.Comment: 9 pages, 3 figure

Catherine of Siena’s wisdom on discernment and her reception of scripture

Catherine of Siena’s wisdom on discernment represents a significant development in the history of this essential Christian theme. Her teaching is the fruit of personal wisdom rather than formal study as she was an uneducated lay woman in fourteenth century Italy. In this article I show how Scripture was central to Catherine’s wisdom. First I show that she was exposed to Scripture primarily orally and that she assimilated what she heard through her life of prayer and relationship with God. I describe the central biblical themes at the heart of her teaching on discernment, namely growth in charity and capacity for truth, and I show how these are related to her wisdom on discernment. I then examine how Catherine applied her teaching through an analysis of a letter to Pope Gregory XI. In this article I will show that central New Testament themes are at the heart of Catherine of Siena’s teaching on discernment and I will describe how the knowledge of Scripture that suffused her teaching was not internalized as a result of formal study, but rather as a result of her experience of God in prayer and of her personal reflection. Her oral reception of Scripture became transformed through her mystical experience into wisdom that has become a major Christian classic; indeed Catherine is one of only three women named Doctor of the Church in the Catholic tradition.peer-reviewe