34 research outputs found
Nonequilibrium orbital magnetization of strongly localized electrons
The magnetic response of strongly localized electrons to a time-dependent
vector potential is considered. The orbital magnetic moment of the system, away
from steady-state conditions, is obtained. The expression involves the
tunneling and phonon-assisted hopping currents between localized states. The
frequency and temperature dependence of the orbital magnetization is analyzed
as function of the admittances connecting localized levels. It is shown that
quantum interference of the localized wave functions contributes to the moment
a term which follows adiabatically the time-dependent perturbation.Comment: RevTeX 3.
Embracing ambiguity in management control and decision-making processes:On how to design data visualizations to prompt wise judgement
Making decisions when managing organizations always involves the constant management of ambiguity and a great deal of complexity due to uncertainties and the intrinsic political nature of every decision-making processes. This paper argues that in order for management accounting to deal effectively with this ambiguity and uncertainty, both must be embraced, not suppressed, by the design of data visualizations produced by management controls as aids to the decision-making processes. Drawing on studies in rhetoric, alongside others on the rhetorical and communicative power of images and visualizations, this paper identifies a series of principles that can contribute to the development of a visual rhetorical framework to inform the design of data visualization (e.g. dashboards, business reports). The need to conceive of data visualisations beyond their representational function, and the principles that are identified, are then illustrated through the visual rhetorical analysis of a complex dashboard utilised in the programme management of the construction of a large airport terminal. The paper ends with an outline of a research agenda for the future design of data visualization in accounting, and beyond
Discrepancy between short-term and long-term effects of bone marrow-derived cell therapy in acute myocardial infarction: a systematic review and meta-analysis
Abstract Background Bone marrow-derived cell therapy has been used to treat acute myocardial infarction. However, the therapeutic efficacy of this approach remains controversial. Here, we performed a systematic review and meta-analysis to evaluate short-term and long-term effectiveness of bone marrow-derived therapy. Methods We searched eight databases (Ovid-Medline, Ovid-EMBASE, Cochrane Library, KoreaMed, KMBASE, KISS, RISS, and KisTi) up to December 2014. Demographic characteristics, clinical outcomes, and adverse events were analyzed. We identified 5534 potentially relevant studies; 405 were subjected to a full-text review. Forty-three studies with 2635 patients were included in this review. Results No safety issues related to cell injection were reported during follow-up. At 6 months, cell-injected patients showed modest improvements in left ventricular ejection fraction (LVEF) compared with the control group. However, there were no differences between groups at other time points. In the cardiac MRI analysis, there were no significant differences in infarct size reduction between groups. Interestingly, mortality tended to be reduced at the 3-year follow-up, and at the 5-year follow-up, cell injection significantly decreased all-cause mortality. Conclusions This meta-analysis demonstrated discrepancies between short-term LV functional improvement and long-term all-cause mortality. Future clinical trials should include long-term follow-up outcomes to validate the therapeutic efficacy of cell therapy
Non-Linear Flutter in Fan Stator Vanes With Time Dependent Fixity
A new mechanism for fan stator vane failure in turbofan engines at high speed and high loading has been identified and reported in this paper. Highly destructive vane failures have been encountered at Honeywell in one of the development fans with composite stator vanes. Measured data indicated nonlinear high amplitude vibratory response in fan stator vanes on stall side of the fan map at high speeds. Analysis showed that under certain vane steady loading vane fixity at hub could change, significantly reducing the vane natural frequency. At lower natural frequency the vane was found to be aeroelastically unstable and calculated response exhibited behavior observed during failure. An engine test was conducted to validate the role of hub fixity in vane failures. Test results showed failure to be a self-excited phenomenon and not driven by an external source of excitation. It was also shown that failures occur in vanes that are not rigidly fixed, validating the role of hub fixity in vane failures. Test results along with the analysis confirm the role of time dependent hub fixity leading to the highly destructive flutter responsible for vane failures.</jats:p
Trajectory Propagation Using Information on Periodicity
Families of methods to integrate first and second order ordinary differential equations whose solution known to be periodic will be discussed. The methods can be tuned to a possibly a-priori knowledge of the user on the location of the frequencies, that are dominant in the exact solution. On the basis of such extra information the truncation error can considerably be reduced in magnitude. The paper compares these methods to well known in integrators and discusses a simple mechanism to estimate the frequency during the integration process
