Situation Awareness in LPNs: a Pilot Study

Purpose: The purpose of this pilot study was to describe situation awareness (SA) among licensed practical nurses (LPNs) working in direct patient care. Specific Aims: The specific aims for this study are 1) to examine SA scores, as measured by the Situation Awareness Global Assessment Technique (SAGAT), in LPNs working in direct patient care and compare to published data on SA in registered nurses (RNs), 2) to examine the relationship between SA scores and years of LPN experience, 3) to examine differences in SA scores by type of workplace setting and 4) to describe the relationship between levels of satisfaction with simulation, as measured by the Satisfaction with Simulation Experience Scale (SSES) and SA scores among LPNs. Framework: Situation Awareness Theory, as described by Endsley, was used as the framework for this study. Design: A cross-sectional, descriptive design using the Situation Awareness Global Assessment Technique was used to gather data from a convenience sample of LPNs. Results: LPNs (N=24) participated in the study and achieved an average SAGAT score of 72.6%. There were no differences in scores between those LPNs enrolled in an RN program and those who were not enrolled. Individual scores on the SAGAT were comparable or better than scores in a similar study of RNs. Conclusion: LPNs in this study demonstrated adequate situation awareness. Key Words: Situation awareness, licensed practical nurse, patient deterioration, clinical simulatio

Two-time autocorrelation function in phase-ordering kinetics from local scale-invariance

The time-dependent scaling of the two-time autocorrelation function of spin systems without disorder undergoing phase-ordering kinetics is considered. Its form is shown to be determined by an extension of dynamical scaling to a local scale-invariance which turns out to be a new version of conformal invariance. The predicted autocorrelator is in agreement with Monte-Carlo data on the autocorrelation function of the 2D kinetic Ising model with Glauber dynamics quenched to a temperature below criticality.Comment: Latex2e, 7 pages with 2 figures, with epl macro, final from, to appear in EP

Scaling of the magnetic linear response in phase-ordering kinetics

The scaling of the thermoremanent magnetization and of the dissipative part of the non-equilibrium magnetic susceptibility is analysed as a function of the waiting-time $s$ for a simple ferromagnet undergoing phase-ordering kinetics after a quench into the ferromagnetically ordered phase. Their scaling forms describe the cross-over between two power-law regimes governed by the non-equilibrium exponents $a$ and $\lambda_R/z$, respectively. A relation between $a$, the dynamical exponent $z$ and the equilibrium exponent $\eta$ is derived from scaling arguments. Explicit tests in the Glauber-Ising model and the kinetic spherical model are presented.Comment: 7 pages, 2 figures included, needs epl.cls, version to appear in Europhys. Let

Ageing and dynamical scaling in the critical Ising spin glass

The non-equilibrium ageing behaviour of the 3D and 4D critical Ising spin glass is studied for both binary and gaussian disorder. The same phenomenology of the time-dependent scaling as in non-disordered magnets is found but the non-equilibrium exponents and the universal limit fluctuation-dissipation ratio depend on the distribution of the coupling constants.Comment: Latex2e, 7 pages with epl macro, 4 figures included, final for

Critical aging of a ferromagnetic system from a completely ordered state

We adapt the non-linear $\sigma$ model to study the nonequilibrium critical dynamics of O(n) symmetric ferromagnetic system. Using the renormalization group analysis in $d=2+\epsilon$ dimensions we investigate the pure relaxation of the system starting from a completely ordered state. We find that the average magnetization obeys the long-time scaling behavior almost immediately after the system starts to evolve while the correlation and response functions demonstrate scaling behavior which is typical for aging phenomena. The corresponding fluctuation-dissipation ratio is computed to first order in $\epsilon$ and the relation between transverse and longitudinal fluctuations is discussed.Comment: 5 pages, revtex

The role of initial conditions in the ageing of the long-range spherical model

The kinetics of the long-range spherical model evolving from various initial states is studied. In particular, the large-time auto-correlation and -response functions are obtained, for classes of long-range correlated initial states, and for magnetized initial states. The ageing exponents can depend on certain qualitative features of initial states. We explicitly find the conditions for the system to cross over from ageing classes that depend on initial conditions to those that do not.Comment: 15 pages; corrected some typo

Impeller optimization in crossflow hydraulic turbines

Crossflow turbines represent a valuable choice for energy recovery in aqueducts, due to their constructive simplicity and good efficiency under variable head jump conditions. Several experimental and numerical studies concerning the optimal design of crossflow hydraulic turbines have already been proposed, but all of them assume that structural safety is fully compatible with the sought after geometry. We show first, with reference to a specific study case, that the geometry of the most efficient impeller would lead shortly, using blades with a traditional circular profile made with standard material, to their mechanical failure. A methodology for fully coupled fluid dynamic and mechanical optimization of the blade cross-section is then proposed. The methodology assumes a linear variation of the curvature of the blade external surface, along with an iterative use of two-dimensional (2D) computational fluid dynamic (CFD) and 3D structural finite element method (FEM) simulations. The proposed methodology was applied to the design of a power recovery system (PRS) turbine already installed in an operating water transport network and was finally validated with a fully 3D CFD simulation coupled with a 3D FEM structural analysis of the entire impeller

A New Cross-Flow Type Turbine for Ultra-Low Head in Streams and Channels

In the last few decades, hydropower production has been moving toward a new paradigm of low and diffused power density production of energy with small and mini-hydro plants, which usually do not require significant water storage. In the case of nominal power lower than 20 kW and ultra-low head H (H < 5 m), Archimedes screw or Kaplan type turbines are usually chosen due to their efficiency, which is higher than 0.85. A new cross-flow type turbine called Ultra-low Power Recovery System (UL-PRS) is proposed and its geometry and design criteria are validated in a wide range of operating conditions through 2D numerical analysis computed using the ANSYS Fluent solver. The new proposed solution is much simpler than the previously mentioned competitors; its outlet flow has a horizontal direction and attains similar efficiency. The costs of the UL-PRS turbine are compared with the costs of one Kaplan and one cross-flow turbine (CFT) in the case study of the main water treatment plant of the city of Palermo in Italy. In this case, the UL-PRS efficiency is estimated using a URANS 3D numerical analysis computed with the CFX solver

Ageing in the critical contact process: a Monte Carlo study

The long-time dynamics of the critical contact process which is brought suddenly out of an uncorrelated initial state undergoes ageing in close analogy with quenched magnetic systems. In particular, we show through Monte Carlo simulations in one and two dimensions and through mean-field theory that time-translation invariance is broken and that dynamical scaling holds. We find that the autocorrelation and autoresponse exponents lambda_{Gamma} and lambda_R are equal but, in contrast to systems relaxing to equilibrium, the ageing exponents a and b are distinct. A recent proposal to define a non-equilibrium temperature through the short-time limit of the fluctuation-dissipation ratio is therefore not applicable.Comment: 18 pages, 7 figures, Latex2e with IOP macros; final for