Experimental verification of democratic particle motions by direct imaging of glassy colloidal systems

We analyze data from confocal microscopy experiments of a colloidal suspension to validate predictions of rapid sporadic events responsible for structural relaxation in a glassy sample. The trajectories of several thousand colloidal particles are analyzed, confirming the existence of rapid sporadic events responsible for the structural relaxation of significant regions of the sample, and complementing prior observations of dynamical heterogeneity. The emergence of relatively compact clusters of mobility allows the dynamics to transition between the large periods of local confinement within its potential energy surface, in good agreement with the picture envisioned long ago by Adam and Gibbs and Goldstein.Comment: 4 pages, 5 figure

Democratic particle motion for meta-basin transitions in simple glass-formers

We use molecular dynamics computer simulations to investigate the local motion of the particles in a supercooled simple liquid. Using the concept of the distance matrix we find that the alpha-relaxation corresponds to a small number of crossings from one meta-basin to a neighboring one. Each crossing is very rapid and involves the collective motion of O(40) particles that form a relatively compact cluster, whereas string-like motions seem not to be relevant for these transitions. These compact clusters are thus candidates for the cooperatively rearranging regions proposed long times ago by Adam and Gibbs.Comment: 4 pages, 4 Postscript figure

Efficiency Analysis of Inorganic Rice Production in Rakit Kulim Subdistrict Indragiri Hulu Regency

Rice is an important commodity because  it is a staple food source for almost all Indonesian people. One way to increase rice production is by using available resources more efficiently. The use of production factors such as land, seeds, fertilizers, pesticides and labor will affect the total production of rice produced. This study aims to determine the technicality of inorganic rice cultivation, calculate production costs and analyze the efficiency of inorganic rice farming production in the District of Rakit Kulim. The analytical method used is descriptive analysis, farming cost analysis and DEA (Data Envelopment Analysis) analysis. The number of samples is 40 inorganic rice farmers. The results showed that the inorganic rice cultivation technique in the District of Rakit Kulim was not in accordance with the recommendations. Incompatibility is caused by the unavailability of technical books for inorganic rice cultivation from the localita specific crop study center. The total cost of producing inorganic rice farming in the District of Rakit Kulim is Rp. 23,622,481, - / Ha. While the average income is Rp. 24,230,168, - / Ha with a net income of 607,687, - / Ha with an RCR value of 1.07. The results of the analysis of production efficiency using DEA show that the proportion of technically efficient farmers is 50% with an average value of 0.946. The proportion of efficient farmers is allocatively relatively small at 32.5% with an average value of 0.975. Economic efficiency is relatively small at 32.5% with an average value of 0.927

Time evolution of dynamic propensity in a model glass former. The interplay between structure and dynamics

By means of the isoconfigurational method we calculate the change in the propensity for motion that the structure of a glass-forming system experiences during its relaxation dynamics. The relaxation of such a system has been demonstrated to evolve by means of rapid crossings between metabasins of its potential energy surface (a metabasin being a group of mutually similar, closely related structures which differ markedly from other metabasins), as collectively relaxing units (d-clusters) take place. We now show that the spatial distribution of propensity in the system does not change significantly until one of these d-clusters takes place. However, the occurrence of a d-cluster clearly de-correlates the propensity of the particles, thus ending up with the dynamical influence of the structural features proper of the local metabasin. We also show an important match between particles that participate in d-clusters and that which show high changes in their propensity.Comment: 7 pages, 8 figures, articl

Spatiotemporal intermittency and localized dynamic fluctuations upon approaching the glass transition

We introduce a new and robust approach for characterizing spatially and temporally heterogeneous behavior within a system based on the evolution of dynamic fuctuations once averaged over different space lengths and time scales. We apply it to investigate the dynamics in two canonical systems as the glass transition is approached: simulated Lennard-Jones liquids and experimental dense colloidal suspensions. We find that in both cases the onset of glassines is marked by spatially localized dynamic fluctuations originating in regions of correlated mobile particles. By removing the trivial system size dependence of the fluctuations we show that such regions contain tens to hundreds of particles for time scales corresponding to maximally non-Gaussian dynamics.Comment: New analysis technique introduced, and applied to previously published dat

Development and testing of the Stakeholder Quality Improvement Perspectives Survey (SQuIPS)

BACKGROUND: To create a theory-informed survey that quality improvement (QI) teams can use to understand stakeholder perceptions of an intervention. METHOD: We created the survey then performed a cross-sectional survey of QI stakeholders of three QI projects. The projects sought to: (1) reduce unplanned extubations in a neonatal intensive care unit; (2) maintain normothermia during colorectal surgery and (3) reduce specimen processing errors for ambulatory gastroenterology procedures. We report frequencies of responses to survey items, results of exploratory factor analysis, and how QI team leaders used the results. RESULTS: Overall we received surveys from 319 out of 386 eligible stakeholders (83% response rate, range for the three QI projects 57%-86%). The QI teams found that the survey results confirmed existing concerns (eg, the intervention would not make work easier) and revealed unforeseen concerns such as lack of consensus about the overall purpose of the intervention and its importance. The results of our factor analysis indicate that one 7-item scale (Cronbach\u27s alpha 0.9) can efficiently measure important aspects of stakeholder perceptions, and that two additional Likert-type items could add valuable information for leaders. Two QI team leaders made changes to their project based on survey responses that indicated the intervention made stakeholders\u27 jobs harder, and that there was no consensus about the purpose of the intervention. CONCLUSIONS: The Stakeholder Quality Improvement Perspectives Survey was feasible for QI teams to use, and identified stakeholder perspectives about QI interventions that leaders used to alter their QI interventions to potentially increase the likelihood of stakeholder acceptance of the intervention

Superintegrability on N-dimensional spaces of constant curvature from so(N+1) and its contractions

The Lie-Poisson algebra so(N+1) and some of its contractions are used to construct a family of superintegrable Hamiltonians on the ND spherical, Euclidean, hyperbolic, Minkowskian and (anti-)de Sitter spaces. We firstly present a Hamiltonian which is a superposition of an arbitrary central potential with N arbitrary centrifugal terms. Such a system is quasi-maximally superintegrable since this is endowed with 2N-3 functionally independent constants of the motion (plus the Hamiltonian). Secondly, we identify two maximally superintegrable Hamiltonians by choosing a specific central potential and finding at the same time the remaining integral. The former is the generalization of the Smorodinsky-Winternitz system to the above six spaces, while the latter is a generalization of the Kepler-Coulomb potential, for which the Laplace-Runge-Lenz N-vector is also given. All the systems and constants of the motion are explicitly expressed in a unified form in terms of ambient and polar coordinates as they are parametrized by two contraction parameters (curvature and signature of the metric).Comment: 14 pages. Based on the contribution presented at the "XII International Conference on Symmetry Methods in Physics", Yerevan (Armenia), July 2006. To appear in Physics of Atomic Nucle