The vector BPS baby Skyrme model

We investigate the relation between the BPS baby Skyrme model and its vector meson formulation, where the baby Skyrme term is replaced by a coupling between the topological current $B_\mu$ and the vector meson field $\omega_\mu$. The vector model still possesses infinitely many symmetries leading to infinitely many conserved currents which stand behind its solvability. It turns out that the similarities and differences of the two models depend strongly on the specific form of the potential. We find, for instance, that compactons (which exist in the BPS baby Skyrme model) disappear from the spectrum of solutions of the vector counterpart. Specifically, for the vector model with the old baby Skyrme potential we find that it has compacton solutions only provided that a delta function source term effectively screening the topological charge is inserted at the compacton boundary. For the old baby Skyrme potential squared we find that the vector model supports exponentially localized solitons, like the BPS baby Skyrme model. These solitons, however, saturate a BPS bound which is a nonlinear function of the topological charge and, as a consequence, higher solitons are unstable w.r.t. decay into smaller ones, which is at variance with the more conventional situation (a linear BPS bound and stable solitons) in the BPS baby Skyrme model.Comment: 20 pages, 4 figure

The Relationship Between Paramedic Competency, Teamwork and Career Development with Quality of Service at Mengwi I Community Health Centre

Background and objective: Recent survey indicated that patient opinion of services at Mengwi I Community Health Centre was low and there was noticeable decline in patient visits. This study aimed to investigate the issues related to the quality of health services given by the paramedics. Methods: A crosssectional study was conducted with 38 paramedics on duty at the outpatient unit. They were interviewed to obtain the data on their opinions about the quality of their service, competence, teamwork and career development opportunities. Chi square test was used for bivariate analysis and logistic regression for multivariate analysis. Results: The results of bivariate analysis indicated there was significant association between the paramedics'quality of service with the competence, teamwork and career development (p<0,001). Multivariate analysis indicated that the paramedics'competence (OR=43,1; 95%CI: 1,3-1422,5) and development of career (OR=31,7; 95%CI: 1,1-829,7) were related to the paramedics' quality of service. Conclusion: The quality of service of paramedics at Mengwi I Community Health Centre were significantly associated with the paramedics'competence and development of career

Thermodynamics of the BPS Skyrme model

One problem in the application of the Skyrme model to nuclear physics is that it predicts too large a value for the compression modulus of nuclear matter. Here we investigate the thermodynamics of the BPS Skyrme model at zero temperature and calculate its equation of state. Among other results, we find that classically (i.e. without taking into account quantum corrections) the compressibility of BPS skyrmions is, in fact, infinite, corresponding to a zero compression modulus. This suggests that the inclusion of the BPS submodel into the Skyrme model lagrangian may significantly reduce this too large value, providing further evidence for the claim that the BPS Skyrme model may play an important role in the description of nuclei and nuclear matter.Comment: Latex, 26 pages, 1 figure; v2: some typos corrected, version accepted for publication in Phys. Rev.

Baryon chemical potential and in-medium properties of BPS skyrmions

We continue the investigation of thermodynamical properties of the BPS Skyrme model. In particular, we analytically compute the baryon chemical potential both in the full field theory and in a mean-field approximation. In the full field theory case, we find that the baryon chemical potential is always exactly proportional to the baryon density, for arbitrary solutions. We further find that, in the mean-field approximation, the BPS Skyrme model approaches the Walecka model in the limit of high density - their thermodynamical functions as well as the equation of state agree in this limit. This fact allows to read off some properties of the $\omega$-meson from the BPS Skyrme action, even though the latter model is entirely based on the (pionic) $SU(2)$ Skyrme field. On the other hand, at low densities, at the order of the usual nuclear matter density, the equations of state of the two models are no longer universal, such that a comparison depends on some model details. Still, also the BPS Skyrme model gives rise to nuclear saturation in this regime, leading, in fact, to an exact balance between repulsive and attractive forces. The perfect fluid aspects of the BPS Skyrme model, which, together with its BPS properties, form the base of our results, are shown to be in close formal analogy with the Eulerian formulation of relativistic fluid dynamics. Within this analogy, the BPS Skyrme model, in general, corresponds to a non-barotropic perfect fluid.Comment: Latex, 28 pages, 3 figure

Editorial of Special Issue Combining Sensors and Multibody Models for Applications in Vehicles, Machines, Robots and Humans

[Abstract] The combination of physical sensors and computational models to provide additional information about system states, inputs and/or parameters, in what is known as virtual sensing, is becoming more and more popular in many sectors, such as the automotive, aeronautics, aerospatial, railway, machinery, robotics and human biomechanics sector

An Automated Methodology to Select Functional Co-Simulation Configurations

[Abstract] The development of machinery often requires system-level analysis, in which non-mechanical subsystems, such as hydraulics, need to be considered. Co-simulation allows analysts to divide a problem into subsystems and use tailored software solutions to deal individually with their respective dynamics. On the other hand, these subsystems must be coupled at particular instants in time, called communication points, through the exchange of coupling variables. Between communication points, each subsystem solver carries out the integration of its states without interacting with its environment. This may cause the integration to become unstable, especially when non-iterative co-simulation is used. The co-simulation configuration, i.e., the parameters and simulation options selected by the analyst, such as the way to handle the coupling variables or the choice of subsystem solvers, is often a critical factor regarding co-simulation stability. In practice it is difficult to anticipate which selection is the most appropriate for a particular problem, especially if some inputs come from external sources, such as human operators, and cannot be determined beforehand. We put forward a methodology to automatically determine a stable and computationally efficient configuration for Jacobi-scheme co-simulation. The method uses energy residuals to gain insight into co-simulation stability. The relation between energy residual and communication step-size is exploited to monitor co-simulation accuracy during a series of tests in which the external inputs are replaced with predetermined input functions. The method was tested with hydraulically actuated mechanical examples. Results indicate that the proposed method can be used to find stable and accurate configurations for co-simulation applications.Ministerio de Economía; RYC-2016-2022