The semidiscrete Galerkin finite element modeling of compressible viscous flow past an airfoil

The primary project was the numerical simulation, by a finite element/finite difference method, of the viscous flow about an airfoil. The secondary project involved the numerical simulation of the three-dimensional separated and vortex-dominated flow about a hemispherically capped cylinder in the transonic regime. Preliminary calculations were started for the hemisphere-cylinder at 0 and 5 degree angle of attack. The solution of the flow field about airfoils and wings is required to determine the important parameters of lift, moment, and drag. Viscous effects must be accounted for if the drag is to be accurately calculated. At present there are basically two approaches to the numerical simulation of the flow field, the use of fully viscous models and the inviscid/viscous models. The fully viscous models require the solution of an approximation of the Navier-Stokes equations and therefore should simulate most of the physical mechanisms. A fast, accurate, and computationally efficient inviscid flow solver was recently developed by Hartwich. It is thought that Hartwich's program coupled to a fast, accurate, and computationally efficient boundary layer code, will make an excellent tool for airfoil design. The purpose of the primary project was to develop a compressible boundary layer code using the semidiscrete Galerkin finite element method. The numerical scheme employed used the combination of a Dorodnitsyn formulation of the boundary layer equations, with a finite difference/finite element procedure (semidiscrete Galerkin method), in the solution of the compressible two-dimensional boundary layer equations. A laminar compressible boundary layer code was developed and tested for a NACA 0012 airfoil at a Mach number of 0.5, a Reynolds number of 5000, and zero angle of attack. At present the boundary layer program solves up to, but not beyond, separation

Block Motion Changes in Japan Triggered by the 2011 Great Tohoku Earthquake

Plate motions are governed by equilibrium between basal and edge forces. Great earthquakes may induce differential static stress changes across tectonic plates, enabling a new equilibrium state. Here we consider the torque balance for idealized circular plates and find a simple scalar relationship for changes in relative plate speed as a function of its size, upper mantle viscosity, and coseismic stress changes. Applied to Japan, the 2011 $\mathrm{M}_{\mathrm{W}}=9.0$ Tohoku earthquake generated coseismic stresses of $10^2-10^5$~Pa that could have induced changes in motion of small (radius $\sim100$~km) crustal blocks within Honshu. Analysis of time-dependent GPS velocities, with corrections for earthquake cycle effects, reveals that plate speeds may have changed by up to $\sim3$ mm/yr between $\sim3.75$-year epochs bracketing this earthquake, consistent with an upper mantle viscosity of $\sim 5\times10^{18}$Pa$\cdot$s, suggesting that great earthquakes may modulate motions of proximal crustal blocks at frequencies as high as $10^-8$~Hz

WISDOM: history and early demise - was it inevitable?

In 1989, the UK Medical Research Council (MRC) agreed that, if feasible, a randomized controlled trial to assess the long-term risks and benefits of hormone replacement therapy (HRT) was a priority. Feasibility work began in 1990 and demonstrated that a large-scale multicenter trial was possible. An application for funding for a main trial was submitted to MRC in 1993 and, after extensive review, funding was released in late 1996. Set-up work for the trial - the Women's International Study of long Duration Oestrogen after Menopause (WISDOM) - began in 1997 with recruitment in 1999. In October 2002, following the early discontinuation of one arm of the US Women's Health Initiative HRT trial, the MRC decided to stop the WISDOM trial. This article, by the principal UK investigators of WISDOM, sets out the background and history of the trial

The use of artificial neural networks in experimental data acquisition and aerodynamic design

It is proposed that an artificial neural network be used to construct an intelligent data acquisition system. The artificial neural networks (ANN) model has a potential for replacing traditional procedures as well as for use in computational fluid dynamics validation. Potential advantages of the ANN model are listed. As a proof of concept, the author modeled a NACA 0012 airfoil at specific conditions, using the neural network simulator NETS, developed by James Baffes of the NASA Johnson Space Center. The neural network predictions were compared to the actual data. It is concluded that artificial neural networks can provide an elegant and valuable class of mathematical tools for data analysis

Long-range electron transfer in structurally engineered pentaammineruthenium (histidine-62) cytochrome c

In many biological processes, long-range electron transfer (ET) plays a key role. When the three-dimensional structures of proteins are accurately known, use of modified proteins and protein-protein complexes provides an experimental approach to study ET rates between two metal centers. For Ru(His)- modified proteins, the introduction of histidine residues at any desired surface location by site-directed mutagenesis opens the way for systematic investigations of ET pathways

Edge-Driven Mechanical Microplate Models of Strike-Slip Faulting in the Tibetan Plateau

The India-Asia collision zone accommodates the relative motion between India and Eurasia through both shortening and pervasive strike-slip faulting. To gain a mechanical understanding of how fault slip rates are driven across the Tibetan plateau, we develop a two-dimensional, linear elastic, two-stage, deformable microplate model for the upper crust based on the behavior of an idealized earthquake cycle. We use this approach to develop a suite of simple India-Asia collision zone models, differing only in boundary conditions, to determine which combination of edge forces and displacements are consistent with both the slip rate measurements along major Tibetan faults as well as the geodetically observed extrusion of crustal material toward Southeast Asia. Model predictions for the Altyn Tagh (1–14 mm/yr), Kunlun (3–10 mm/yr), Karakorum (5–12 mm/yr), and Haiyuan (3–5 mm/yr) faults are in agreement with geologically and geodetically inferred slip rates. Further, models that accurately reproduce observed slip rate gradients along the Altyn Tagh and Kunlun faults feature two critical boundary conditions: (1) oblique compressive displacement along the Himalayan range front west of the Shillong plateau, and (2) forcing in Southeast Asia. Additionally, the ratio of internal-block potency rate to the total potency rate for each microplate ranges from 28% to 79%, suggesting a hybrid view of deformation in Tibet as simultaneously localized on major faults and distributed at length scales <500 km.Earth and Planetary Science

Spatial Correlation of Interseismic Coupling and Coseismic Rupture Extent of the 2011 MW_W = 9.0 Tohoku-oki Earthquake

Imaging the extent to which the rupture areas of great earthquakes coincide with regions of pre-seismic interplate coupling is central to understanding patterns of strain accumulation and release through the earthquake cycle. Both geodetic and seismic estimates of the coseismic rupture extent for the March 11, 2011 $M_W = 8.9–9.0$ earthquake Tohoku-oki earthquake may be spatially correlated (0.26 ± 0.05 to 0.82 ± 0.05) with a region estimated to be partially to fully coupled in the interseismic period preceding the earthquake, though there is substantial variation in the estimated distribution and magnitude of coseismic slip. The ∼400 km-long region estimated to have slipped ≥4 m corresponds to an area of the subduction zone interface that was coupled at ≥30% of long-term plate convergence rate, with peak slip near a region coupled ≥80%. The northern termination of rupture is collocated with a region of relatively low (<20%) interseismic coupling near the epicenter of the 1994 $M_W = 7.6$ Sanriku-oki earthquake, and near a region of potential long-term low coupling or ongoing slow slip. Slip on the subduction interface beneath the coastline (40–50 km depth) is best constrained by the land-based GPS data and least constrained on the shallowest portion of the plate interface due to the ∼230 km distance between geodetic observations and the Japan trench.Earth and Planetary Science

Geodetic Imaging of Coseismic Slip and Postseismic Afterslip: Sparsity Promoting Methods Applied to the Great Tohoku Earthquake

Geodetic observations of surface displacements during and following earthquakes such as the March 11, 2011 great Tohoku earthquake can be used to constrain the spatial extent of coseismic slip and postseismic afterslip, and characterize the spectrum of earthquake cycle behaviors. Slip models are often regularized by assuming that slip on the fault varies smoothly in space, which may result in the artificial smearing of fault slip beyond physical boundaries. Alternatively, it may be desirable to estimate a slip distribution that is spatially compact and varies sharply. Here we show that sparsity promoting state vector regularization methods can be used to recover slip distributions with sharp boundaries, representing an alternative end-member result to very smooth slip distributions. Using onshore GPS observations at 298 stations during and in the ∼2 weeks following the Tohoku earthquake, we estimate a band of coseismic slip between 30 and 50 km depth extending 500 km along strike with a maximum slip of 64 m, corresponding to a minimum magnitude estimate of $M_W = 8.8$. Our estimate of afterslip is located almost exclusively down-dip of the coseismic rupture, with a transition between 40 and 50 km depth and an equivalent moment magnitude $M_W = 8.2$. This depth may be interpreted as coincident with the transition from velocity strengthening to velocity weakening frictional behavior, consistent with the upper limit of cold subduction estimates of the thermal structure of the Japan trench.Earth and Planetary Science

Efficient CRISPR-rAAV engineering of endogenous genes to study protein function by allele-specific RNAi.

Gene knockout strategies, RNAi and rescue experiments are all employed to study mammalian gene function. However, the disadvantages of these approaches include: loss of function adaptation, reduced viability and gene overexpression that rarely matches endogenous levels. Here, we developed an endogenous gene knockdown/rescue strategy that combines RNAi selectivity with a highly efficient CRISPR directed recombinant Adeno-Associated Virus (rAAV) mediated gene targeting approach to introduce allele-specific mutations plus an allele-selective siRNA Sensitive (siSN) site that allows for studying gene mutations while maintaining endogenous expression and regulation of the gene of interest. CRISPR/Cas9 plus rAAV targeted gene-replacement and introduction of allele-specific RNAi sensitivity mutations in the CDK2 and CDK1 genes resulted in a &gt;85% site-specific recombination of Neo-resistant clones versus ∼8% for rAAV alone. RNAi knockdown of wild type (WT) Cdk2 with siWT in heterozygotic knockin cells resulted in the mutant Cdk2 phenotype cell cycle arrest, whereas allele specific knockdown of mutant CDK2 with siSN resulted in a wild type phenotype. Together, these observations demonstrate the ability of CRISPR plus rAAV to efficiently recombine a genomic locus and tag it with a selective siRNA sequence that allows for allele-selective phenotypic assays of the gene of interest while it remains expressed and regulated under endogenous control mechanisms