Stability transitions for axisymmetric relative equilibria of Euclidean symmetric Hamiltonian systems

In the presence of noncompact symmetry, the stability of relative equilibria under momentum-preserving perturbations does not generally imply robust stability under momentum-changing perturbations. For axisymmetric relative equilibria of Hamiltonian systems with Euclidean symmetry, we investigate different mechanisms of stability: stability by energy-momentum confinement, KAM, and Nekhoroshev stability, and we explain the transitions between these. We apply our results to the Kirchhoff model for the motion of an axisymmetric underwater vehicle, and we numerically study dissipation induced instability of KAM stable relative equilibria for this system.Comment: Minor revisions. Typographical errors correcte

Oral health improvement for nursing home residents through delegated remotivation and reinstruction (MundZaRR Study): study protocol of a cluster-randomised controlled trial

Introduction: Oral health and oral health-related quality of life (OHrQL) of residents in German long-term residential care (LRC) are poor. We will develop an evidence-based catalogue of interventions ('Oral Health Toolbox') and provide care-accompanying reinstruction and remotivation of nursing staff by dental assistants (DA). We hypothesise that such intervention will significantly improve OHrQL, daily oral hygiene/care behaviour and is cost-effective. Methods and analysis: A scoping review will be used to identify possible intervention components. Mixed methods will be used to identify barriers and enablers of oral hygiene and care in German LRC. The result will be the 'Oral Health Toolbox', a two-phased instrument supporting both initial intervention allocation to improve oral health/hygiene and reinstruction/remotivation. A two-arm clustered, randomised controlled trial (ratio of 1:1 via block randomisation) will be performed in LRC in Rhineland-Palatinate, Germany. Each nursing home represents a cluster. Based on a feasibility study, considering clustering and possible attrition, we aim at recruiting 618 residents in 18 clusters. In the intervention group, dentists will assign one or more intervention component from the box (phase 1). During follow-up, nursing staff will be reinstructed and remotivated by DA, who use the box to decide how to maintain the intervention (phase 2). In the control group residents will receive care as usual. The primary outcome, OHrQL, will be measured using the General Oral Health Assessment Index. Secondary outcomes include pain condition, general health-related quality of life, caries increment, oral/prosthetic hygiene and gingival status, incidence of dental emergencies and hospitalisations, and cost-utility/effectiveness. The endpoints will be measured at baseline and after 12 months. For our primary outcome, a mixed-linear model will be used within an intention-to-treat analysis. A process evaluation using mixed methods will be conducted alongside the trial. Ethics and dissemination: Ethical approval by the University of Kiel was granted (D480/18). Trial registration number: NCT04140929

Dependence of geosynchrotron radio emission on the energy and depth of maximum of cosmic ray showers

Based on CORSIKA and REAS2 simulations, we investigate the dependence of geosynchrotron radio emission from extensive air showers on the energy of the primary cosmic ray and the depth of the shower maximum. It is found that at a characteristic lateral distance, the amplitude of the bandpass-filtered radio signal is directly proportional to the energy deposited in the atmosphere by the electromagnetic cascade, with an RMS uncertainty due to shower-to-shower fluctuations of less than 3%. In addition, the ratio of this radio amplitude and that at a larger lateral distance is directly related to the atmospheric depth of the shower maximum, with an RMS uncertainty of ~15-20 g cm-2. By measuring these quantities, geosynchrotron radio emission from cosmic ray air showers can be used to infer the energy of the primary particle and the depth of the air shower maximum on a shower-to-shower basis.Comment: version accepted by Astroparticle Physics; slightly changed title and wording; one additional figur

Infinitely many periodic orbits for the rhomboidal five-body problem

We prove the existence of infinitely many symmetric periodic orbits for a regularized rhomboidal five-body problem with four small masses placed at the vertices of a rhombus centered in the fifth mass. The main tool for proving the existence of such periodic orbits is the analytic continuation method of Poincaré together with the symmetries of the problem. © 2006 American Institute of Physics

Linear stability in billiards with potential

A general formula for the linearized Poincar\'e map of a billiard with a potential is derived. The stability of periodic orbits is given by the trace of a product of matrices describing the piecewise free motion between reflections and the contributions from the reflections alone. For the case without potential this gives well known formulas. Four billiards with potentials for which the free motion is integrable are treated as examples: The linear gravitational potential, the constant magnetic field, the harmonic potential, and a billiard in a rotating frame of reference, imitating the restricted three body problem. The linear stability of periodic orbits with period one and two is analyzed with the help of stability diagrams, showing the essential parameter dependence of the residue of the periodic orbits for these examples.Comment: 22 pages, LaTex, 4 Figure

Perceptions of managerial staff on the patient safety culture at a tertiary hospital in South Africa

Background: Hospital managers are best suited and located to enhance patient safety culture within their institutions. Aim: This study sought to provide insight on the perceptions of 10 managerial staff regarding the patient safety culture at a tertiary academic hospital in South Africa. Method: In-depth interviews were conducted with strategic and operational managers within high-risk units in order to determine their perceptions regarding patient safety culture. Findings: Participants described diverse aspects of the hospital's patient safety culture including an overview of patient safety, implementation of patient safety initiatives, challenges to patient safety, current management of patient safety issues, as well as ways to improve the patient safety culture of the hospital. Conclusion: The findings highlighted a number of areas to improve on to advance patient safety within the South African context. These include improving basic services, strengthening the infrastructure, improving staff attitudes and implementation of patient safety initiatives. Further research and development of quality improvement plans are essential to enhance patient safety

Are We Ready to Ride Autonomous Vehicles? A Pilot Study on Austrian Consumers’ Perspective

Automotive manufacturers are competing to be the first to introduce customer-ready autonomous vehicles. Some manufacturers are claiming to launch their first self-driving cars as early as 2020. Which all sounds very good and futuristic; however, the question arises, are customers even ready to adopt this new technological advancement? Therefore, this pilot study is aimed at finding out the answer to this question in the Austrian market. This study discovers the standpoint of Austrian consumers concerning the acceptance of self-driving cars for daily usage and gives an overview of the current point of view regarding autonomous vehicles (AVs). The data for this study was collected using an online, user-friendly, Likert scale survey. The collected data were processed and analyzed for empirical significance in SPSS using Spearman’s rank correlation and the Mann–Whitney U test supported by descriptive analysis. The results of the study indicate that Austrian consumers are well aware of autonomous vehicles and their technology. However, they have specific concerns about reliability, cybersecurity, and futuristic car-sharing models. Therefore, these concerns about AVs should be addressed by auto manufactures in order to gain consumers’ trust and sell them a new form of mobility

The confined-deconfined Interface Tension and the Spectrum of the Transfer Matrix

The reduced tension $\sigma_{cd}$ of the interface between the confined and the deconfined phase of $SU(3)$ pure gauge theory is related to the finite size effects of the first transfer matrix eigenvalues. A lattice simulation of the transfer matrix spectrum at the critical temperature $T_c = 1/L_t$ yields $\sigma_{cd} = 0.139(4) T_c^2$ for $L_t = 2$. We found numerical evidence that the deconfined-deconfined domain walls are completely wet by the confined phase, and that the confined-deconfined interfaces are rough.Comment: 22 pages, LaTeX file with 4 ps figures included, HLRZ 92-47, BUTP-92/3

Methods for detecting flaring structures in Sagittarius A* with high frequency VLBI

The super massive black hole candidate, Sagittarius A*, exhibits variability from radio to X-ray wavelengths on time scales that correspond to < 10 Schwarzschild radii. We survey the potential of millimeter-wavelength VLBI to detect and constrain time variable structures that could give rise to such variations, focusing on a model in which an orbiting hot spot is embedded in an accretion disk. Non-imaging algorithms are developed that use interferometric closure quantities to test for periodicity, and applied to an ensemble of hot-spot models that sample a range of parameter space. We find that structural periodicity in a wide range of cases can be detected on most potential VLBI arrays using modern VLBI instrumentation. Future enhancements of mm/sub-mm VLBI arrays including phased array processors to aggregate VLBI station collecting area, increased bandwidth recording, and addition of new VLBI sites all significantly aid periodicity detection. The methods described herein can be applied to other models of Sagittarius A*, including jet outflows and Magneto-Hydrodynamic accretion simulations.Comment: Submitted to Ap