Fluctuation theorem and extended thermodynamics of turbulence.

Turbulent flows are out-of-equilibrium because the energy supply at large scales and its dissipation by viscosity at small scales create a net transfer of energy among all scales. This energy cascade is modelled by approximating the spectral energy balance with a nonlinear Fokker-Planck equation consistent with accepted phenomenological theories of turbulence. The steady-state contributions of the drift and diffusion in the corresponding Langevin equation, combined with the killing term associated with the dissipation, induce a stochastic energy transfer across wavenumbers. The fluctuation theorem is shown to describe the scale-wise statistics of forward and backward energy transfer and their connection to irreversibility and entropy production. The ensuing turbulence entropy is used to formulate an extended turbulence thermodynamics.

Evaluation of opioid requirements in the management of renal colic after guideline implementation in the emergency department.

PURPOSE: Evaluate opioid prescribing before and after emergency department (ED) renal colic guideline implementation focused on multi-modal pain management. METHODS: Retrospective study of ED patients who received analgesia for urolithiasis before and after guideline implementation. The guideline recommends oral acetaminophen, intravenous (IV) ketorolac, and a fluid bolus as first line, IV lidocaine as second line, and opioids as refractory therapy to control pain. Opioid exposure, adverse effects, length of stay (LOS), and ED representation were evaluated. Comparisons were made with univariate analyses. Backwards stepwise binomial multivariate logistic regression to identify factors related to opioid use was performed. RESULTS: Overall, 962 patients were included (451 pre- and 511 post-implementation). ED and discharge opioid use decreased; 65% vs. 58% and 71% vs. 63% in pre- and post-implementation groups, respectively. More post-implementation patients received non-opioid analgesia (65% vs. 56%) and non-opioid analgesia prior to opioids (50% vs. 38%). A longer ED LOS and higher initial pain score were associated with ED opioid administration. Guideline implementation, receiving non-opioid therapy first, and first renal colic episode were associated with decreased ED opioid administration. Seventeen adverse events (1.8%) were reported. There was no difference in change in ED pain score between groups, but patients in the post-implementation group were admitted more and had a higher 7-day ED representation (11% vs. 7%). CONCLUSIONS: A multimodal analgesia protocol for renal colic was associated with decreased opioid prescribing, higher rates of admission to the hospital, and a higher 7-day ED representation rate.

Pediatric Genitourinary Infections and Other Considerations.

Pediatric patients pose a unique host of challenges to the emergency provider across all complaints and ages, but this is particularly notable in the genitourinary (GU) system. The pediatric GU system is different from that of the adult in its etiology of symptoms, complications, and treatments. Based on age, there are variations in the anatomy. These differences result in symptoms and diagnoses that must be managed differently. Although in many respects management is similar to GU emergency conditions in adults, there are, occasionally subtle, differences between the care of children and adults, which can greatly impact outcomes.

Mechanisms for the clustering of inertial particles in the inertial range of isotropic turbulence.

In this paper, we consider the physical mechanism for the clustering of inertial particles in the inertial range of isotropic turbulence. We analyze the exact, but unclosed, equation governing the radial distribution function (RDF) and compare the mechanisms it describes for clustering in the dissipation and inertial ranges. We demonstrate that in the limit Str≪1, where Str is the Stokes number based on the eddy turnover time scale at separation r, the clustering in the inertial range can be understood to be due to the preferential sampling of the coarse-grained fluid velocity gradient tensor at that scale. When Str≳O(1) this mechanism gives way to a nonlocal clustering mechanism. These findings reveal that the clustering mechanisms in the inertial range are analogous to the mechanisms that we identified for the dissipation regime [see New J. Phys. 16, 055013 (2014)]. Further, we discuss the similarities and differences between the clustering mechanisms we identify in the inertial range and the "sweep-stick" mechanism developed by Coleman and Vassilicos [Phys. Fluids 21, 113301 (2009)]. We show that the idea that initial particles are swept along with acceleration stagnation points is only approximately true because there always exists a finite difference between the velocity of the acceleration stagnation points and the local fluid velocity. This relative velocity is sufficient to allow particles to traverse the average distance between the stagnation points within the correlation time scale of the acceleration field. We also show that the stick part of the mechanism is only valid for Str≪1 in the inertial range. We emphasize that our clustering mechanism provides the more fundamental explanation since it, unlike the sweep-stick mechanism, is able to explain clustering in arbitrary spatially correlated velocity fields. We then consider the closed, model equation for the RDF given in Zaichik and Alipchenkov [Phys. Fluids 19, 113308 (2007)] and use this, together with the results from our analysis, to predict the analytic form of the RDF in the inertial range for Str1, which, unlike that in the dissipation range, is not scale invariant. The results are in good agreement with direct numerical simulations, provided the separations are well within the inertial range.