A computer program for the calculation of laminar and turbulent boundary layer flows

The results are presented of a study to produce a computer program to calculate laminar and turbulent boundary layer flows. The program is capable of calculating the following types of flow: (1) incompressible or compressible, (2) two dimensional or axisymmetric, and (3) flows with significant transverse curvature. Also, the program can handle a large variety of boundary conditions, such as blowing or suction, arbitrary temperature distributions and arbitrary wall heat fluxes. The program has been specialized to the calculation of equilibrium air flows and all of the thermodynamic and transport properties used are for air. For the turbulent transport properties, the eddy viscosity approach has been used. Although the eddy viscosity models are semi-empirical, the model employed in the program has corrections for pressure gradients, suction and blowing and compressibility. The basic method of approach is to put the equations of motion into a finite difference form and then solve them by use of a digital computer. The program is written in FORTRAN 4 and requires small amounts of computer time on most scientific machines. For example, most laminar flows can be calculated in less than one minute of machine time, while turbulent flows usually require three or four minutes

Particle-in-cell simulation study of the scaling of asymmetric magnetic reconnection with in-plane flow shear

We investigate magnetic reconnection in systems simultaneously containing asymmetric (anti-parallel) magnetic fields, asymmetric plasma densities and temperatures, and arbitrary in-plane bulk flow of plasma in the upstream regions. Such configurations are common in the high-latitudes of Earth's magnetopause and in tokamaks. We investigate the convection speed of the X-line, the scaling of the reconnection rate, and the condition for which the flow suppresses reconnection as a function of upstream flow speeds. We use two-dimensional particle-in-cell simulations to capture the mixing of plasma in the outflow regions better than is possible in fluid modeling. We perform simulations with asymmetric magnetic fields, simulations with asymmetric densities, and simulations with magnetopause-like parameters where both are asymmetric. For flow speeds below the predicted cutoff velocity, we find good scaling agreement with the theory presented in Doss et al., J.~Geophys.~Res., 120, 7748 (2015). Applications to planetary magnetospheres, tokamaks, and the solar wind are discussed.Comment: 17 pages, 4 figures, submitted to Physics of Plasma

Modified NASA-Lewis chemical equilibrium code for MHD applications

A substantially modified version of the NASA-Lewis Chemical Equilibrium Code was recently developed. The modifications were designed to extend the power and convenience of the Code as a tool for performing combustor analysis for MHD systems studies. The effect of the programming details is described from a user point of view

Asymmetric magnetic reconnection with a flow shear and applications to the magnetopause

We perform a theoretical and numerical study of anti-parallel 2D magnetic reconnection with asymmetries in the density and reconnecting magnetic field strength in addition to a bulk flow shear across the reconnection site in the plane of the reconnecting fields, which commonly occurs at planetary magnetospheres. We predict the speed at which an isolated X-line is convected by the flow, the reconnection rate, and the critical flow speed at which reconnection no longer takes place for arbitrary reconnecting magnetic field strengths, densities, and upstream flow speeds, and confirm the results with two-fluid numerical simulations. The predictions and simulation results counter the prevailing model of reconnection at Earth's dayside magnetopause which says reconnection occurs with a stationary X-line for sub-Alfvenic magnetosheath flow, reconnection occurs but the X-line convects for magnetosheath flows between the Alfven speed and double the Alfven speed, and reconnection does not occur for magnetosheath flows greater than double the Alfven speed. We find that X-line motion is governed by momentum conservation from the upstream flows, which are weighted differently in asymmetric systems, so the X-line convects for generic conditions including sub-Alfvenic upstream speeds. For the reconnection rate, while the cutoff condition for symmetric reconnection is that the difference in flows on the two sides of the reconnection site is twice the Alfven speed, we find asymmetries cause the cutoff speed for asymmetric reconnection to be higher than twice the asymmetric form of the Alfven speed. The results compare favorably with an observation of reconnection at Earth's polar cusps during a period of northward interplanetary magnetic field, where reconnection occurs despite the magnetosheath flow speed being more than twice the magnetosheath Alfven speed, the previously proposed suppression condition.Comment: 46 pages, 7 figures, abstract abridged here, accepted to Journal of Geophysical Research - Space Physic

Durability of mitral valve reconstruction using the cosgrove edwards annuloplasty band at 5 years : From 23rd World Congress of the World Society of Cardio-Thoracic Surgeons. Split, Croatia. 12-15 September 2013

Oral presentation: 23rd World Congress of the World Society of Cardio-Thoracic Surgeons. Split, Croatia. 12-15 September 2013. Background: In the past, questions have been raised, whether an open flexible annuloplasty band can reliably prevent recurrent mitral valve regurgitation. The purpose of this study was to evaluate the durability of mitral valve repair at midterm, using the Cosgrove-Edwards annuloplasty band in a homogenic patient cohort. Methods: From January 2004 to December 2007, 157 consecutive patients with degenerative mitral valve disease were included in the study. All had quadrangular resection of a P2 prolapse and annuloplasty with a Cosgrove-Edwards annuloplasty band. Clinical and echocardiography follow-up was complete. Results: There was no intraoperative or 30 day mortality. After a mean follow-up of 5.0 ± 1.9 years, survival was 94.3%. At midterm, freedom from reoperations was 98.9%, freedom from thromboembolism was 97.5% and freedom from endocarditis was 99.4%. Echocardiography follow-up showed recurrent mitral valve regurgitation higher than grade 2 in two patients. Mean ejection fraction was 60.3 ± 10.2%, left atrial diameter was 42 ± 7 mm, mean gradient was 3.2 ± 1.4 mmHg, effective orifice area was 3.3 ± 1.3cm², mitral leaflet coaptation length was 7.5 ± 1.9 mm and mitral leaflet tethering height was 6.2 ± 2.3 mm. Conclusion: Mitral valve repair using the Cosgrove annuloplasty band for degenerative mitral valve disease provides an effective and durable form of reconstruction

Oblique radiative shocks, including their interactions with nonradiative polytropic shocks

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98755/1/PhysPlasmas_18_056901.pd

Laser-Ionized Underdense Passive Plasma Lens for Focusing Electron Beams

Next generation accelerators and colliders using relativistic electron beams are continuously pushing the demand for higher luminosity beams with smaller and smaller spot sizes. To address this need, passive plasma lenses operating in the nonlinear blowout regime of beam-driven plasma wakefield acceleration (PWFA) are capable of providing focusing forces to electron beams orders of magnitude stronger than conventional quadrupole magnets. To realize these lenses in practice, high intensity lasers can be used to ionize a small volume of gas and producing a plasma lens with precisely determined density profile. The quality of an electron beam focused by a plasma lens is determined by the phase space evolution of the beam while it is within the plasma wakefield. The strong electric fields can also increase an electron beam's emittance through chromatic phase spreading, which deteriorates the transverse quality of the beam. This dissertation covers the formalism used to describe the focusing of an electron beam from a passive, underdense plasma lens and demonstrates use cases for these lenses in experiments using relativistic electron beams. To perform plasma lens experiments, we propose a setup to ionize a 100&nbsp;&micro;m&nbsp;scale plasma lens via laser ionization of a gas jet outflow at the FACET-II accelerator facility of SLAC National Accelerator Laboratory. We investigate possible focusing aberrations induced by nonuniform transverse density profiles. Finally, we report on experimental progress towards the demonstration of an underdense thin plasma lens, including the analysis of preliminary data from commissioning shifts carried out at FACET-II.</p

The Implementation of a Validated CSEC Screening Tool for Youth Age 11 - 17 in a Pediatric Emergency Room

Abuse of children is a public health issue covering a range of inflicted harm from neglect to physical to sexual abuse. A severe form of child sexual abuse is the Commercial Sexual Exploitation of Children (CSEC). This phenomenon involves sexual crimes against children, including exploitation for gain. High-risk indicators are noted throughout the literature to aid in identification, but some children are vulnerable because of their young age. Perpetrators can be family, friends, or acquaintances and choose their potential victims by recognizing a child’s vulnerabilities. Inevitable physical and mental health consequences are associated with CSEC involvement; hence these youth seek out healthcare. They do not self-identify because they do not see themselves as victims and are not identified by Healthcare Providers (HCP) due to knowledge deficit and decreased awareness. Healthcare providers are in pivotal roles in identifying these victims as they seek out healthcare, however, training and a validated screening tool are needed to enable the identification of high-risk youth. Research questions: 1) Will a CSEC educational intervention and the implementation of a validated CSEC screening tool, increase the confidence levels of licensed healthcare providers in a Pediatric Emergency Room in identifying high-risk youth age 11 – 17 over baseline confidence levels? 2) Will the implementation of a validated CSEC screening tool in a Pediatric Emergency Room increase the rate of referrals of high-risk youth age 11 – 17 over pre-implementation rate as determined by retrospective chart review? Sample/population: Licensed HCPs in a Pediatric Emergency Room Research Design: Cross-sectional with pre and post-test (confidence levels) and retrospective chart review (referral rate). Statistical analysis using descriptive statistics, paired-samples t-tests, and Pearson’s r and Spearman’s rho correlations were performed. Results showed that there was an increase in perceived confidence levels, no increase in the referral rate; however, documentation by the HCP did improve