A comparison of operator splitting and approximate matrix factorization for the shallow water equations in spherical geometry

spherical geometry;The shallow water equations (SWEs) in spherical geometry provide abasic prototypefor developing and testing numerical algorithms for solving the horizontaldynamics in global atmospheric circulation models. When solving the SWEs on a global fine uniform lat-lon grid, an explicit timeintegration method suffers from a severe stability restriction on theadmissible step size. In a previous paper, we investigated an A-stable,linearly-implicit, third-order time integration method (Ros3), which wecombinedwith approximate matrix factorization (AMF) to make it cost-effective. Inthis paper, we further explore this method and we compare itto a Strang-type operator splitting method. Our main focus is on the localerror of the methods, their numerical dispersion relation and their accuracyand efficiency when applied to the well-known SWEs test set. Thecomparison shows that Ros3with AMF accurately presents both low and mid frequency waves. Moreover,Ros3 with AMF makes a good candidate for theefficient solution of the SWEs on a global fine lat-longrid. In contrast, Strang splitting is not advocated, in view of itsinaccuracy in the polar area and the resulting inefficiency

Edge Guided Reconstruction for Compressive Imaging

We propose EdgeCS—an edge guided compressive sensing reconstruction approach—to recover images of higher quality from fewer measurements than the current methods. Edges are important image features that are used in various ways in image recovery, analysis, and understanding. In compressive sensing, the sparsity of image edges has been successfully utilized to recover images. However, edge detectors have not been used on compressive sensing measurements to improve the edge recovery and subsequently the image recovery. This motivates us to propose EdgeCS, which alternatively performs edge detection and image reconstruction in a mutually beneficial way. The edge detector of EdgeCS is designed to faithfully return partial edges from intermediate image reconstructions even though these reconstructions may still have noise and artifacts. For complex-valued images, it incorporates joint sparsity between the real and imaginary components. EdgeCS has been implemented with both isotropic and anisotropic discretizations of total variation and tested on incomplete k-space (spectral Fourier) samples. It applies to other types of measurements as well. Experimental results on large-scale real/complex-valued phantom and magnetic resonance (MR) images show that EdgeCS is fast and returns high-quality images. For example, it exactly recovers the 256×256 Shepp–Logan phantom from merely 7 radial lines (3.03% k-space), which is impossible for most existing algorithms. It is able to accurately reconstruct a 512 × 512 MR image with 0.05 white noise from 20.87% radial samples. On complex-valued MR images, it obtains recoveries with faithful phases, which are important in many medical applications. Each of these tests took around 30 seconds on a standard PC. Finally, the algorithm is GPU friendly

Comparison of full-scale, small-scale, and CFD results for F/A-18 forebody slot blowing

It has been shown experimentally that forebody flow control devices provide a significant increase in yaw control for fighter aircraft at high angle-of-attack. This study presents comparisons of the various experimental and computational results for tangential slot blowing on the F/A-18 configuration. Experimental results are from the full-scale and 6 percent-scale model test and computational solutions are from both isolated forebody and and full aircraft configurations. The emphasis is on identifying trends in the variation of yawing moment with blowing-slot exit conditions. None of the traditional parameters (mass flow ratio, blowing momentum coefficient, velocity ratio) succeeded in collapsing all of the results into a common curve. Several factors may effect the agreement between the 6 percent- and full-scale results including Reynolds number effects, sensitivity of boundary layer transition from laminar to turbulent flow, and poor geometric fidelity, particularly of the blowing slot. The disagreement between the full-scale and computed yawing moments may be due to a mismatch in the slot exit conditions for the same mass flow ratio or aircraft configuration modeling. The general behavior of slot blowing on the 6 percent-scale and computational models is correct, but neither matches the full-scale results

Identification of a Unique TGF-β Dependent Molecular and Functional Signature in Microglia

Microglia are myeloid cells of the central nervous system (CNS) that participate both in normal CNS function and disease. We investigated the molecular signature of microglia and identified 239 genes and 8 microRNAs that were uniquely or highly expressed in microglia vs. myeloid and other immune cells. Out of 239 genes, 106 were enriched in microglia as compared to astrocytes, oligodendrocytes and neurons. This microglia signature was not observed in microglial lines or in monocytes recruited to the CNS and was also observed in human microglia. Based on this signature, we found a crucial role for TGF-β in microglial biology that included: 1) the requirement of TGF-β for the in vitro development of microglia that express the microglial molecular signature characteristic of adult microglia; and 2) the absence of microglia in CNS TGF-β1 deficient mice. Our results identify a unique microglial signature that is dependent on TGF-β signaling which provides insights into microglial biology and the possibility of targeting microglia for the treatment of CNS disease

High Alpha Technology Program (HATP) ground test to flight comparisons

This status paper reviews the experimental ground test program of the High Alpha Technology Program (HATP). The reasons for conducting this ground test program had their origins during the 1970's when several difficulties were experienced during the development programs of both the F-18 and F-16. A careful assessment of ground test to flight correlations appeared to be important for reestablishing a high degree of confidence in our ground test methodology. The current paper will then focus on one aspect of the HATP program that is intended to improve the correlation between ground test and flight, high-alpha gritting. The importance of this work arises from the sensitivity of configurations with smooth-sided forebodies to Reynolds number. After giving examples of the effects of Reynolds number, the paper will highlight efforts at forebody gritting. Finally, the paper will conclude by summarizing the charter of the HATP Experimental Aerodynamics Working Group and future experimental testing plans

Design and statistics of pharmacokinetic drug-drug, herb-drug, and food-drug interaction studies in oncology patients

Polypharmacy is becoming increasingly prevalent in society. Patients with polypharmacy are at greater risk for drug-drug interactions, which can influence the efficacy of treatment. Especially, in oncology this is a concern since neoplasms are increasing prevalent with age, as well as polypharmacy is. Besides drug-drug interactions, also herb-drug and food-drug interactions could be present. Knowledge of these interactions is of great importance for safe and effective anti-cancer treatment, because the therapeutic window of most of these oncologic drugs are small. To study pharmacokinetic interaction effects, a cross-over pharmacokinetic study is a widely used, efficient and scientifically robust design. Yet, several aspects need to be considered when carrying out an interaction study. This includes the knowledge of the advantages and disadvantages of a cross-over design. Furthermore, determination of the end point and research question of interest, calculation of the required sample size, analysis of the generated data with a robust statistical plan and consideration of the logtransformation for some pharmacokinetic parameters are important aspects to consider. Even though some guidelines exist regarding these key issues, no clear overview exists. In this article an overview of these aspects is provided and their effect is discussed