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Beginning in the fall of 1998 and continuing to the present, an assessment study has been in progress to determine the effectiveness of visualization modules used in a basic engineering class at the United States Air Force Academy (USAFA). This paper discusses the progression of this assessment study. Until recently, there has been a lack of content(More)
—This paper demonstrates a practical approach to developing a geometrically scalable thermal resistance model to optimize layout for improved electrical performance of high-power RF transistors. The model is developed using finite element-based simulations, which show very good agreement with measured results. The proposed modeling methodology pre-computes(More)
Wavelet packet analysis is a mathematical transformation that can be used to post-process images, for example, to remove image noise ("denoising"). At a very low signal-to-noise ratio (SNR <5), standard magnitude magnetic resonance images have skewed Rician noise statistics that degrade denoising performance. Since the quadrature images have approximately(More)
BACKGROUND Measurement of myocardial iron is key to the clinical management of patients at risk of siderotic cardiomyopathy. The cardiovascular magnetic resonance relaxation parameter R2* (assessed clinically via its reciprocal, T2*) measured in the ventricular septum is used to assess cardiac iron, but iron calibration and distribution data in humans are(More)
RATIONALE Sickle cell disease is an inherited blood disorder characterized by vasoocclusive crises. Although hypoxia and pulmonary disease are known risk factors for these crises, the mechanisms that initiate vasoocclusive events are not well known. OBJECTIVES To study the relationship between transient hypoxia, respiration, and microvascular blood flow(More)
BACKGROUND Transfusional therapy for thalassemia major and sickle cell disease can lead to iron deposition and damage to the heart, liver, and endocrine organs. Iron causes the MRI parameters T1, T2, and T2* to shorten in these organs, which creates a potential mechanism for iron quantification. However, because of the danger and variability of cardiac(More)
Disturbances of executive functioning after traumatic brain injury represent significant obstacles to social and vocational recovery and may require specific remedial intervention. We report the treatment of a client with impaired planning ability and poor self-control after closed head injury. Intervention consisted of a self-instructional procedure that(More)
Iron-induced cardiac dysfunction is a leading cause of death in transfusion-dependent anemia. MRI relaxation rates R2(1/T2) and R2*(1/T2*) accurately predict liver iron concentration, but their ability to predict cardiac iron has been challenged by some investigators. Studies in animal models support similar R2 and R2* behavior with heart and liver iron,(More)
This paper compares and contrasts recent nonlinear behavioral modeling techniques designed for microwave and RFIC applications which arise in radio and communication systems, and in the design of broad-band nonlinear components used for microwave instrumentation. These techniques include dynamic neural networks and nonlinear time series models in the(More)