An efficient surrogate model for emulation and physics extraction of large eddy simulations

In the quest for advanced propulsion and power-generation systems, high-fidelity simulations are too computationally expensive to survey the desired design space, and a new design methodology is needed that combines engineering physics, computer simulations and statistical modeling. In this paper, we propose a new surrogate model that provides efficient prediction and uncertainty quantification of turbulent flows in swirl injectors with varying geometries, devices commonly used in many engineering applications. The novelty of the proposed method lies in the incorporation of known physical properties of the fluid flow as {simplifying assumptions} for the statistical model. In view of the massive simulation data at hand, which is on the order of hundreds of gigabytes, these assumptions allow for accurate flow predictions in around an hour of computation time. To contrast, existing flow emulators which forgo such simplications may require more computation time for training and prediction than is needed for conducting the simulation itself. Moreover, by accounting for coupling mechanisms between flow variables, the proposed model can jointly reduce prediction uncertainty and extract useful flow physics, which can then be used to guide further investigations.Comment: Submitted to JASA A&C

The Impact of Prenatal Exposure to Cocaine on Newborn Costs and Length of Stay

This paper determines newborn costs and lengths of stay attributable to prenatal exposure to cocaine and other illicit drugs, using as a data source all parturients who delivered at a large municipal hospital in New York City between November 18, 1991 and April 11, 1992. We performed a cross-sectional analysis in which multivariate, loglinear regressions were used to analyze differences in costs and length of stay between infants exposed and unexposed prenatally to cocaine and other illicit drugs adjusting for maternal race, age, prenatal care, tobacco, parity, type of delivery, birth weight, prematurity, and newborn infection. Urine specimens, with linked obstetric sheets and discharge abstracts provided information on exposure, prenatal behaviors, costs, length of stay and discharge disposition. Our principal findings show that infants exposed to cocaine and some other illicit drug stay approximately 7 days longer at a cost of $7,731 more than infants unexposed. Approximately 60 percent of these costs are indirect, the result of adverse birth outcomes and newborn infection. Hospital screening as recorded on discharge abstracts substantially underestimates prevalence at delivery, but overestimates its impact on costs.

Acceptance dependence of fluctuation measures near the QCD critical point

We argue that a crucial determinant of the acceptance dependence of fluctuation measures in heavy-ion collisions is the range of correlations in the momentum space, e.g., in rapidity, $\Delta y_{\rm corr}$. The value of $\Delta y_{\rm corr}\sim1$ for critical thermal fluctuations is determined by the thermal rapidity spread of the particles at freezeout, and has little to do with position space correlations, even near the critical point where the spatial correlation length $\xi$ becomes as large as $2-3$ fm (this is in contrast to the magnitudes of the cumulants, which are sensitive to $\xi$). When the acceptance window is large, $\Delta y\gg\Delta y_{\rm corr}$, the cumulants of a given particle multiplicity, $\kappa_k$, scale linearly with $\Delta y$, or mean multiplicity in acceptance, $\langle N\rangle$, and cumulant ratios are acceptance independent. While in the opposite regime, $\Delta y\ll\Delta y_{\rm corr}$, the factorial cumulants, $\hat\kappa_k$, scale as $(\Delta y)^k$, or $\langle N\rangle^k$. We demonstrate this general behavior quantitatively in a model for critical point fluctuations, which also shows that the dependence on transverse momentum acceptance is very significant. We conclude that extension of rapidity coverage proposed by STAR should significantly increase the magnitude of the critical point fluctuation signatures.Comment: 9 pages, 4 figures, references adde

News on spectra from the NA61/SHINE experiment

NA61/SHINE is a fixed target experiment at the CERN Super-Proton-Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. In order to reach these goals, a study of hadron production properties is performed in nucleus-nucleus, proton-proton and proton-nucleus interactions as a function of collision energy and size of the colliding nuclei. In this talk, recent results on particle production in p+p interactions, as well as Be+Be and Ar+Sc collisions in the SPS energy range are reviewed. Transverse momentum, transverse mass and rapidity spectra obtained with various analysis methods are presented. Surprises in studies of signatures of onset of deconfinement are discussed. The results are compared with available world data

Confining forces

We discuss the forces on the internal constituents of the hadrons based on the bag model. The ground state of the hadrons forms a color singlet so that the effects of the colored internal states are neutralized. From the breaking of the dilatation and conformal symmetries under the strong interactions the corresponding currents are not conserved. These currents give rise to the forces changing the motion of the internal particles which causes confinement.Comment: 8 pages, 2 figure

News from strong interactions program of the NA61/SHINE experiment

The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. This is performed by a two dimensional phase diagram ($T-\mu_B$) scan of measurements of particle spectra and fluctuations in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy and system size. In this contribution new NA61/SHINE results on negative pion production, as well as transverse momentum and multiplicity fluctuations in Ar+Sc collisions are presented. Moreover, the latest results on higher order moments of net-charge multiplicity distribution in p+p collisions are also discussed. The Ar+Sc results are compared to NA61 p+p and Be+Be data, as well as to NA49 $A+A$ results.Comment: Presented at the Critical Point and Onset of Deconfinement 2016, Wroclaw, Poland, May 30th - June 4th, 2016 (v2: Fig. 2 - labels corrected, references updated