Magnetic properties of the double perovskites LaPbMSbO6 (M = Mn, Co and Ni)

New double perovskites LaPbMSbO6, where M2+ = Mn2+, Co2+, and Ni2+, were synthesized as polycrystals by an aqueous synthetic route at temperatures below 1000 oC. All samples are monoclinic, space group P21/n, as obtained from Rietveld analysis of X-ray powder diffraction patterns. The distribution of M2+ and Sb5+ among the two octahedral sites have 3% of disorder for M2+ = Ni2+, whereas for M2+ = Mn2+ and Co2+ less disorder is found. The three samples have an antiferromagnetic transition, due to the antiferromagnetic coupling between M2+ through super-superexchange paths M2+ - O2- - Sb5+ - O2- - M2+. Transition temperatures are low: 8, 10 and 17 K for Mn2+, Co2+, and Ni2+ respectively, as a consequence of the relatively long distances between the magnetic ions M2+. Besides, for LaPbMnSbO6 a small transition at 45 K was found, with ferrimagnetic characteristics, possibly as a consequence of a small disorder between Mn2+ and Sb5+. This disorder would give additional and shorter interaction paths: superexchange Mn2+ - O2- - Mn2+.Comment: 4 pages, 4 figures included. Manuscript submitted to IEEE Transactions on Magnetics, proceedings of the LAW3M 2013 conferenc

Position and Mode Dependent Optical Detection Back-Action in Cantilever Beam Resonators

Optical detection back-action in cantilever resonant or static detection presents a challenge when striving for state-of-the-art performance. The origin and possible routes for minimizing optical back-action have received little attention in literature. Here, we investigate the position and mode dependent optical back-action on cantilever beam resonators. A high power heating laser (100 {\mu}W) is scanned across a silicon nitride cantilever while its effect on the first three resonance modes is detected via a low-power readout laser (1 {\mu}W) positioned at the cantilever tip. We find that the measured effect of back-action is not only dependent on position but also the shape of the resonance mode. Relevant silicon nitride material parameters are extracted by fitting the temperature-dependent frequency response of the first three modes to finite element (FE) simulations. In a second round of simulations, using the extracted parameters, we successfully fit the FEM results with the measured mode and position dependent back-action. Finally, different routes for minimizing the effect of this optical detection back-action are described, allowing further improvements of cantilever-based sensing in general

Automatic Configuration For Remote Diagnosis And Monitoring Of Railway Equipments

Today, there is no standard system for performing maintenance on heterogeneous railway equipments. Maintenance staff needs a standard application capable of diagnosing and monitoring heterogeneous on-board equipments. We propose to build a web-based diagnosis and monitoring system. The main advantage of our approach is that it offers a well known and user friendly interface: a web browser (such as Netscape Navigator or Microsoft Internet Explorer). In addition, it gives the possibility for remote diagnosis and monitoring railway equipments. Thus experts, not necessarily on site in the depot, can make diagnosis and detect faulty components. They can inspect, more than one vehicle at a time, directly from their office. The on-board communication system and related network management services provide a unified entry point to the train data for diagnosis. We have built an automatic configuration approach for such a maintenance system. As a result, this maintenance system can be installed on any vehicle without previous device-specific knowledge about that vehicle. This paper is intended for people concerned with industrial applications to the Internet and especially for those developing remote monitoring tools for embedded devices

Four-fold basal plane anisotropy of the nonlocal magnetization of YNi2B2C

Studies of single crystal YNi2B2C have revealed a four-fold anisotropy of the equilibrium magnetization in the square crystallographic basal plane. This pi/2 periodicity occurs deep in the superconductive mixed state. In this crystal symmetry, an ordinary superconductive mass anisotropy (as in usual London theory) allows only a constant, isotropic response. In contrast, the experimental results are well described by generalized London theory incorporating non-local electrodynamics, as needed for this clean, intermediate-k superconductor.Comment: 4 pages, 4 figure

Number and gender of two terms: architecture and music in Anna Bofill Levi

Releyendo el escrito autobiográfico de la arquitecta y compositora Anna Bofill Levi, Generation of Forms : Space to Inhabit, Time to Think (2009), se analizan dos arriesgadas vertientes de su trayectoria creativa arquitectónica y musical: la exploración de métodos matemáticos y su pionera perspectiva de género.ENG: On rereading Generation of Forms : Space to Inhabit, Time to Think (2009), the autobiography of architect and composer Ana Bofill Levi, we distinguish two risky tangents in both her architectural and musical creative trajectories: the exploration of mathematical methods and her pioneer perspective on gender.Peer Reviewe

A Tragic Solution to the Collective Action Problem: Implications for Corruption, Conflict and Inequality

We study the role of an enforcer in the e§ectiveness of selective incentives in solving the collective action problem when groups take part in a contest. Cost functions exhibit constant elasticity of marginal e§ort costs. If prize valuations are homogeneous, our source of heterogeneity induces full costsharing and the Örst-best individual contributions; further, the group probability of winning goes up. With heterogeneity in prize valuations, an increase in the e§ectiveness of the enforcer in conáict increases the group probability of winning only if the prize valuation of the enforcer is lower than de Lehmer mean of those of the other players; however, the induced partial cost sharing is not group e¢ cient. If e§ectiveness "tends to inÖnity", the collective action problem is solved with partial cost-sharing if that prize valuation is not too low. Tragically, if productivity is low (if the prize is private in our set up) this occurs with corrupt coalitions which have been shown to form together with conáict and inequality endogenously; otherwise, this occurs with non corrupt coalitions. Further, even if such valuation is too low the group winning probability goes up. In this latter case, over cost-sharing yields group e¢ ciency