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AbstractJ Thorac Cardiovasc Surg 2002;124:14-

Computation of steady and unsteady quasi-one-dimensional viscous/inviscid interacting internal flows at subsonic, transonic, and supersonic Mach numbers

Computations of viscous-inviscid interacting internal flowfields are presented for steady and unsteady quasi-one-dimensional (Q1D) test cases. The unsteady Q1D Euler equations are coupled with integral boundary-layer equations for unsteady, two-dimensional (planar or axisymmetric), turbulent flow over impermeable, adiabatic walls. The coupling methodology differs from that used in most techniques reported previously in that the above mentioned equation sets are written as a complete system and solved simultaneously; that is, the coupling is carried out directly through the equations as opposed to coupling the solutions of the different equation sets. Solutions to the coupled system of equations are obtained using both explicit and implicit numerical schemes for steady subsonic, steady transonic, and both steady and unsteady supersonic internal flowfields. Computed solutions are compared with measurements as well as Navier-Stokes and inverse boundary-layer methods. An analysis of the eigenvalues of the coefficient matrix associated with the quasi-linear form of the coupled system of equations indicates the presence of complex eigenvalues for certain flow conditions. It is concluded that although reasonable solutions can be obtained numerically, these complex eigenvalues contribute to the overall difficulty in obtaining numerical solutions to the coupled system of equations

Heart Transplantation in Biventricular Congenital Heart Disease: Indications, Techniques, and Outcomes

Heart transplantation is an accepted therapeutic modality for end-stage congenital heart disease for both biventricular and univentricular anomalies. Many transplant centers have pushed the limits of transplantation to include patients with high pulmonary vascular resistance, high panel reactive antibodies, positive cross-matches, and ABO-incompatibility. Excellent results have been possible, particularly with the development of improved diagnostic and therapeutic algorithms to prevent and treat rejection, infection, and post-transplant lymphoproliferative disease. Late graft failure and chronic rejection remain vexing problems. The vast majority of patients with biventricular congenital heart disease have undergone prior cardiac surgical procedures. Indications for transplantation in this subgroup are primarily progressive refractory heart failure following prior cardiac surgical reconstructive procedures. Contraindications to transplantation mimic those for other forms of end-stage heart disease. A determination of pulmonary vascular resistance is important in listing patients with biventricular congenital heart disease for heart transplantation. Modifications in the implant technique are necessary and vary depending on underlying recipient anatomy. Risk factors for perioperative outcomes in patients with biventricular congenital heart disease include the need for reoperation, the degree of anatomic reconstruction necessary during the implant procedure, and the degree of antibody sensitization, in addition to a number of other recipient and donor factors. Postoperative outcomes and survival are very good but remain inferior to those with cardiomyopathy in most series. In conclusion, patients with end-stage biventricular congenital heart disease represent a complex group of patients for heart transplantation, and require careful evaluation and management to ensure optimal outcomes

In Orbit Attitude Determination, Control and Stabilization Performance of the STRL 1a and 1b MicroSatellites from the UK Defence Research Agency

This paper describes the in orbit performance of the Attitude, Determination, Control and Stabilization systems employed for the Satellite Technology Research Vehicles of the United Kingdom Defence Research Agency. These two satellites will be launched in June 1994 from an Ariane 4 launcher in to Geostationary Transfer Orbit. There is a requirement to ensure that the spin axis of the satellites is maintained in a position approximately 90 degrees to the Sun vector. The satellites are spin stabilized from launch by the 3rd stage launcher rotation and additionally STRV 1a uses cold gas zenon thrusters. Each satellite has a nutation damper and is fitted with a magnetotorquer coil for control actuation since aerodynamic torque correction is required. Full attitude determination is anticipated to be accurate to +/- 1 degree from lightweight, low-cost V-split Sun and Earth sensors. Telemetered control of the actuation system will be via time tagged commands due to the restricted visibility of the satellites to the ground stations

Randomized Trial on the Effectiveness of Dexamethasone in TMJ Arthrocentesis

The aim of this study was to compare the effectiveness of dexamethasone administration following arthrocentesis of the temporomandibular joint (TMJ) with a placebo (saline). Twenty-eight participants with TMJ arthralgia were randomly assigned to two groups of a parallel double-blind RCT. In both groups, an arthrocentesis procedure was carried out. In one group, the procedure was followed by the administration of a single-dose intra-articular dexamethasone. In the other group, saline was administered as a control. Follow-up visits were scheduled after 1, 3, and 24 weeks. During each visit, TMJ pain (on a 100-mm VAS) and jaw stiffness (mouth opening in mm) were scored. In the statistical analysis, generalized estimating equation (GEE) models showed no differences between the two study groups, although pain and jaw stiffness were both reduced over 24 weeks. In conclusion, intra-articular dexamethasone following arthrocentesis did not improve the procedure's effect in patients presenting with TMJ arthralgia (ClinicalTrials.gov number CT01275014)

Case study: copyright issues in distance education

Over the years, much attention has been given to copyright law in literature and as it pertains to textbooks and other original academic works. However, as the focus is narrowed to the copyright law as it relates to distance education within higher education, very little information or precedents can be looked to for guidance. For an institution of higher education involved in distance education, the problem demands that a model be developed specifically for universities to follow as they embrace distance education programs and course development. As the likelihood of lawsuits and grievances clearly exists, the motivation of faculty to create original works is potentially compromised when there is conflict between themselves and the universities who employ them. In addition, a set of guidelines in the form of a model lends a structural basis to university educators and administrators alike on which to formulate the process of developing distance education programs with a greatly reduced chance of legal incident. A case study design was chosen because it adds strength to what is known and deepens understanding of complex issues. According to Lincoln and Guba in their 1985 book, qualitative research involves the studied use and collection of a variety of empirical materials: case study, personal experience, introspective, life story, interview, observational, historical, interactive, and visual texts that describe routine and problematic moments and meanings in individual

Erythema Nodosum Associated With Streptococcal Infection in Pregnancy

Background: Erythema nodosum (EN) is a condition characterized by the presence of painful erythematous nodules on the pretibial aspects of the lower extremities. EN is thought to be a local inflammatory, immune-mediated reaction to a number of systemic antigenic stimuli. This condition is noted most often in women between menarche and menopause and is associated with certain drugs, infections, and pregnancy. However, no reports in the literature describe EN as a result of streptococcal infection during pregnancy