Discrete Lie Advection of Differential Forms

In this paper, we present a numerical technique for performing Lie advection of arbitrary differential forms. Leveraging advances in high-resolution finite volume methods for scalar hyperbolic conservation laws, we first discretize the interior product (also called contraction) through integrals over Eulerian approximations of extrusions. This, along with Cartan's homotopy formula and a discrete exterior derivative, can then be used to derive a discrete Lie derivative. The usefulness of this operator is demonstrated through the numerical advection of scalar fields and 1-forms on regular grids.Comment: Accepted version; to be published in J. FoC

Biocidal activity in soils by biochar from pyrolysis biorefinery process

Useful soil applications of biochar, the biocarbon solid coproduct of biomass pyrolysis, will likely improve the economics of pyrolysis biorefineries. Adding biochar to soils to achieve any number of goals should also consider unintended effects upon soil biology. Herein, we explored two biocidal activities of fluidized-bed fast pyrolysis biochars (FPBC) created over a temperature range of 450-700 oC on the survival of pathogenic E. coli O157:H7 and beneficial arbuscular mycorrhizas (AM) symbioses in soils. For pathogen decontamination, FPBC created at \u3c 500°C proved microbiologically inert, while that created at 600°C proved biocidal over 7 weeks of sampling (P \u3c 0.05) with populations significantly reduced at 3% and 3.5% concentration (5.34 and 5.84 log CFU/g, respectively) compared with concentrations of 0.0-2.0%. Ageing of FPBC created under similar conditions for 2 years resulted in loss of efficacy. FPBC greatly reduced colonization of roots by the AM fungus when we examined the interaction of biochar addition and arbuscular mycorrhizal (AM) fungus inoculation upon growth and phosphorus (P) uptake by Allium porrum L. These responses could be related to physicochemical properties of the biochars as higher surface areas were accompanied by higher AM fungus colonization. The findings are pertinent to selecting pyrolysis biorefinery biochars for application to agricultural soils for purposes such as inactivation of pathogenic bacteria while being mindful of potential impacts upon the AM symbiosis if applied. Biochar II: Production, Characterization and Applications. Cetraro (Calabrial) Italy, September 15-20, 2019

First Principles Analysis of Electron-Phonon Interaction in Graphene

The electron-phonon interaction in monolayer graphene is investigated by using density functional perturbation theory. The results indicate that the electron-phonon interaction strength is of comparable magnitude for all four in-plane phonon branches and must be considered simultaneously. Moreover, the calculated scattering rates suggest an acoustic phonon contribution that is much weaker than previously thought, revealing the role of optical phonons even at low energies. Accordingly it is predicted, in good agreement with a recent measurement, that the intrinsic mobility of graphene may be more than an order of magnitude larger than the high values reported in suspended samples.Comment: 12 pages, 4 figure

Bidirectional Brush Seals: Post-Test Analysis

A post-test analysis of a set of inside-diameter/outside-diameter (ID/OD) bidirectional brush seals used in three-port wave rotor tests was undertaken to determine brush bristle and configuration wear, pullout, and rotor coating wear. The results suggest that sharp changes in the pressure profiles were not well reflected in bristle tip configuration patterns or wear. Also, positive-to-negative changes in axial pressure gradients appeared to have little effect on the backing plates. Although the brushes had similar porosities, they had very different unpacked arrays. This difference could explain the departure of experimental data from computational fluid dynamics flow predictions for well-packed arrays at higher pressure drops. The rotor wear led to "car-track" scars (upper and lower wear bands) with a whipped surface between the bands. Those bands may have resulted from bristle stiffening at the fence and gap plates during alternate portions of the rotor cycle. Within the bristle response range the wear surface reflected the pressure distribution effect on bristle motion. No sacrificial metallurgical data were taken. The bristles did wear, with correspondingly more wear on the ID brush configurations than on the OD configurations; the complexity in constructing the ID brush was a factor

Abuse Assessment Screen–Disability (AAS-D): Measuring Frequency, Type, and Perpetrator of Abuse toward Women with Physical Disabilities

An interview questionnaire was presented to a multiethnic sample of 511 women, age 18–64 years, at public and private specialty clinics to determine the frequency, type, and perpetrator of abuse toward women with physical disabilities. The four-question Abuse Assessment Screen–Disability (AAS-D) instrument detected a 9.8% prevalence (50 of 511) of abuse during the previous 12 months. Using two standard physical and sexual assault questions, 7.8% of the women (40 of 511) reported abuse. The two disability-related questions detected an additional 2.0% of the women (10 of 511) as abused. Women defining themselves as other than black, white, or Hispanic (i.e., Asian, mixed ethnic background) were more likely to report physical or sexual abuse or both, whereas disability-related abuse was reported almost exclusively by white women. The perpetrator of physical or sexual abuse was most likely to be an intimate partner. Disability-related abuse was attributed equally to an intimate partner, a care provider, or a health professional. This study concludes that both traditional abuse-focused questions and disability-specific questions are required to detect abuse toward women with physical disabilities

Large-eddy simulation of the lid-driven cubic cavity flow by the spectral element method

This paper presents the large-eddy simulation of the lid-driven cubic cavity flow by the spectral element method (SEM) using the dynamic model. Two spectral filtering techniques suitable for these simulations have been implemented. Numerical results for Reynolds number $\text{Re}=12'000$ are showing very good agreement with other experimental and DNS results found in the literature

Quadrupolar effect and rattling motion in heavy fermion superconductor PrOs_4Sb_{12}

The elastic properties of a filled skutterudite PrOs_4Sb_{12} with a heavy Fermion superconductivity at T_C=1.85 K have been investigated. The elastic softening of (C_{11}-C_{12})/2 and C_{44} with lowering temperature down to T_C indicates that the quadrupolar fluctuation due to the CEF state plays a role for the Cooper paring in superconducting phase of PrOs_4Sb_{12}. A Debye-type dispersion in the elastic constants around 30 K revealed a thermally activated Gamma_{23} rattling due to the off-center Pr-atom motion obeying tau=tau_{0}exp(E/k_{B}T) with an attempt time tau_0=8.8*10^{-11} sec and an activation energy E=168 K. It is remarkable that the charge fluctuation of the off-center motion with Gamma_{23} symmetry may mix with the quadrupolar fluctuation and enhance the elastic softening of (C_{11}-C_{12})/2 just above T_C.Comment: 5 pages, 4 figures, to be published to Phys. Rev.