Disorder driven destruction of a phase transition in a superconductor

We investigate the effects of disorder on a layered superconductor. The clean system is known to have a first order phase transition which is clearly identified by a sharp peak in the specific heat. The peak is lost abruptly as the strength of the disorder is increased. Hence, for strong disorder there is no phase transition as a function of temperature but merely a crossover which is still detectable in the IV characteristic.Comment: 3 pages REVTeX , 5 figure

Systemic Exercise-Induced Hypoalgesia Following Isometric Exercise Reduces Conditioned Pain Modulation

Objective Physically active individuals show greater conditioned pain modulation (CPM) compared with less active individuals. Understanding the effects of acute exercise on CPM may allow for a more targeted use of exercise in the management of pain. This study investigated the effects of acute isometric exercise on CPM. In addition, the between-session and within-session reliability of CPM was investigated. Design Experimental, randomized crossover study. Setting Laboratory at Marquette University. Subjects Thirty healthy adults (19.3±1.5 years, 15 males). Methods Subjects underwent CPM testing before and after isometric exercise (knee extension, 30% maximum voluntary contraction for three minutes) and quiet rest in two separate experimental sessions. Pressure pain thresholds (PPTs) at the quadriceps and upper trapezius muscles were assessed before, during, and after ice water immersions. Results PPTs increased during ice water immersion (i.e., CPM), and quadriceps PPT increased after exercise (P \u3c 0.05). CPM decreased similarly following exercise and quiet rest (P \u3e 0.05). CPM within-session reliability was fair to good (intraclass correlation coefficient [ICC] = 0.43–0.70), and the between-session reliability was poor (ICC = 0.20–0.35). Due to the variability in the systemic exercise-induced hypoalgesia (EIH) response, participants were divided into systemic EIH responders (N = 9) and nonresponders (N = 21). EIH responders experienced attenuated CPM following exercise (P = 0.03), whereas the nonresponders showed no significant change (P \u3e 0.05). Conclusions Isometric exercise decreased CPM in individuals who reported systemic EIH, suggesting activation of shared mechanisms between CPM and systemic EIH responses. These results may improve the understanding of increased pain after exercise in patients with chronic pain and potentially attenuated CPM

What Does CEOs’ Personal Leverage Tell Us About Corporate Leverage?

We find that firms behave remarkably similarly to how their CEOs behave personally when it comes to leverage choices. We start our analysis by compiling a comprehensive sample of home purchases and financings among S&P 1,500 CEOs. Debt financing in a CEO’s most recent home purchase is used as a revealed preference of the CEO’s personal attitude towards debt. We find a robust positive relation between personal and corporate leverage. We also find that firms tend to hire CEOs with a similar personal attitude towards debt as the previous CEO. When the new and previous CEOs have different personal preferences, corporate leverage changes in the direction of the new CEO’s personal leverage. These results support a model with endogenous matching of CEOs to firms. We also find that the positive relation between CEOs’ personal leverage and corporate leverage is stronger in firms with poor governance, suggesting that CEOs imprint their personal preferences on the firms they manage when they are able to do so. These results suggest that heterogeneity in CEOs’ personal attitudes towards debt partly explains differences in corporate capital structures, and suggest more generally that an analysis of CEOs’ personalities and personal traits may provide important information about the financial policies of the firms they manage.Corporate leverage; personal leverage; CEO characteristics

A footnote to the Poincaré complete reducibility theorem

Poincaré's work on the reduction of abelian integrals contains implicitly an algorithm for the expression of a theta function as a sum of products of theta functions of fewer variables in the presence of reduction . The aim of this paper is to give explicit formulations and reasonably complete proofs of Poincaré's results

Pea-barley intercrop N dynamics in farmers fields

Knowledge about crop performances in farmers’ fields provides a link between on-farm practice and re-search. Thereby scientists may improve their ability to understand and suggest solutions for the problems facing those who have the responsibility of making sound agricultural decisions. Nitrogen (N) availability is known to be highly heterogeneous in terrestrial plant communities (Stevenson and van Kessel, 1997), a heterogeneity that in natural systems is often associated with variation in the distri-bution of plant species. In intercropping systems the relative proportion of component crops is influenced by the distribution of growth factors such as N in both time and space (Jensen, 1996). In pea-barley intercrops, an increase in the N supply promotes the growth of barley thereby decreasing the N accumulation of pea and giving rise to changes in the relative proportions of the intercropped components (Jensen, 1996). The pres-sure of weeds may, however, significantly change the dynamics in intercrops (Hauggaard-Nielsen et al., 2001). Data from farmers’ fields may provide direct, spatially explicit information for evaluating the poten-tials of improving the utilisation of field variability by intercrops