Extracting the intrinsic switching field distribution in perpendicular media: a comparative analysis

We introduce a new method based on the first-order-reversal-curve (FORC) diagram to extract the intrinsic (microscopic) switching-field distribution (SFD) of perpendicular recording media (PRM). To demonstrate the viability of the method, we micromagnetically simulated FORCs for PRM with known SFD and compare the extracted SFD with the SFD obtained by means of two different methods that are based on recoil loops, too, which however rely on mean-field approximations and assumptions on the shape of the SFD. The FORC method turns out to be the most accurate algorithm over a broad range of dipolar interaction strengths, where the other methods overestimate the width of the SFD.Comment: 3 pages with 2 figures, 3 supplemental figures; submitted to J. Appl. Phys. (MMM Annual Conference Proceedings

Cellular Prion Protein Mediates Toxic Signaling of Amyloid Beta

Prion diseases in humans and animals comprise a group of invariably fatal neurodegenerative diseases characterized by the formation of a pathogenic protein conformer designated PrPSc and infectious particles denoted prions. The cellular prion protein (PrPC) has a central role in the pathogenesis of prion disease. First, it is the precursor of PrPSc and infectious prions and second, its expression on neuronal cells is required to mediate toxic effects of prions. To specifically study the role of PrPC as a mediator of toxic signaling, we have developed novel cell culture models, including primary neurons prepared from PrP-deficient mice. Using these approaches we have been able to show that PrPC can interact with and mediate toxic signaling of various beta-sheet-rich conformers of different origins, including amyloid beta, suggesting a pathophysiological role of the prion protein beyond prion diseases. Copyright (C) 2011 S. Karger AG, Base

Biophysics of magnetic orientation: strengthening the interface between theory and experimental design

The first demonstrations of magnetic effects on the behaviour of migratory birds and homing pigeons in laboratory and field experiments, respectively, provided evidence for the longstanding hypothesis that animals such as birds that migrate and home over long distances would benefit from possession of a magnetic sense. Subsequent identification of at least two plausible biophysical mechanisms for magnetoreception in animals, one based on biogenic magnetite and another on radical-pair biochemical reactions, led to major efforts over recent decades to test predictions of the two models, as well as efforts to understand the ultrastructure and function of the possible magnetoreceptor cells. Unfortunately, progress in understanding the magnetic sense has been challenged by: (i) the availability of a relatively small number of techniques for analysing behavioural responses to magnetic fields by animals; (ii) difficulty in achieving reproducible results using the techniques; and (iii) difficulty in development and implementation of new techniques that might bring greater experimental power. As a consequence, laboratory and field techniques used to study the magnetic sense today remain substantially unchanged, despite the huge developments in technology and instrumentation since the techniques were developed in the 1950s. New methods developed for behavioural study of the magnetic sense over the last 30 years include the use of laboratory conditioning techniques and tracking devices based on transmission of radio signals to and from satellites. Here we consider methodological developments in the study of the magnetic sense and present suggestions for increasing the reproducibility and ease of interpretation of experimental studies. We recommend that future experiments invest more effort in automating control of experiments and data capture, control of stimulation and full blinding of experiments in the rare cases where automation is impossible. We also propose new experiments to confirm whether or not animals can detect magnetic fields using the radical-pair effect together with an alternate hypothesis that may explain the dependence on light of responses by animals to magnetic field stimuli

A Case for Soft Systems Methodology: Information Analysis and Information Systems Evaluation During Organizational Change

The complex relationship between organizations, information technology (IT) and information systems (IS) indicates that changes to the organization are likely to have an effect on the usefulness of existing IS and the success of IS projects. Information needs of new and existing users have to be assessed and organizational IS evaluated for their capability to satisfy these needs. This paper describes a real world case study during which Soft Systems Methodology (SSM) was used for information analysis and IS evaluation during organizational change. The research indicates that the methodology provides a suitable framework for inquiry in a complex situation, where roles are ill-defined and political tensions are rife. The use of SSM helped the researcher make sense of the situation under consideration and provided positive, concrete outcomes for the case study organization

Frustration Driven Stripe Domain Formation in Co/Pt Multilayer Films

We report microscopic mechanisms for an unusual magnetization reversal behavior in Co/Pt multilayers where some of the first-order reversal curves protrude outside of the major loop. Transmission x-ray microscopy reveals a fragmented stripe domain topography when the magnetic field is reversed prior to saturation, in contrast to an interconnected pattern when reversing from a saturated state. The different domain nucleation and propagation behaviors are due to unannihilated domains from the prior field sweep. These residual domains contribute to random dipole fields that impede the subsequent domain growth and prevent domains from growing as closely together as for the interconnected pattern.Comment: 13 pages, 3 figures, to appear in AP

Co-creating corporate brand identity with online brand communities: a managerial perspective

Contemporary branding literature views brand identity as socially constructed through complex interactions between multiple stakeholders. Despite extant work on how brand communities and individuals contribute towards brand identity formation, our understanding of management-led processes constituting part of the wider process of a socially constructed brand identity is still under-developed. Drawing on in-depth interviews with senior executives of a luxury automotive company and a netnography of its online brand community, we develop a process model of corporate brand identity co-creation, comprising three management-led processes: ‘nurturing brand passion’, ‘bridging’ corporate brand identity meanings and ‘partnering’, and associated activities through which management contribute to the wider process of corporate brand identity formation with community members and other stakeholders. By highlighting the interlinked and recursive nature of these processes and activities in the resulting model, the study offers a deeper understanding of the ways in which management are involved in co-creating corporate brand identity