Secondary electric power generation with minimum engine bleed

Secondary electric power generation with minimum engine bleed is discussed. Present and future jet engine systems are compared. The role of auxiliary power units is evaluated. Details of secondary electric power generation systems with and without auxiliary power units are given. Advanced bleed systems are compared with minimum bleed systems. A cost model of ownership is given. The difference in the cost of ownership between a minimum bleed system and an advanced bleed system is given

Systems study for an Integrated Digital-Electric Aircraft (IDEA)

The results of the Integrated Digital/Electric Aircraft (IDEA) Study are presented. Airplanes with advanced systems were, defined and evaluated, as a means of identifying potential high payoff research tasks. A baseline airplane was defined for comparison, typical of a 1990's airplane with advanced active controls, propulsion, aerodynamics, and structures technology. Trade studies led to definition of an IDEA airplane, with extensive digital systems and electric secondary power distribution. This airplane showed an improvement of 3% in fuel use and 1.8% in DOC relative to the baseline configuration. An alternate configuration, an advanced technology turboprop, was also evaluated, with greater improvement supported by digital electric systems. Recommended research programs were defined for high risk, high payoff areas appropriate for implementation under NASA leadership

Quantitative scintigraphy with deconvolutional analysis for the dynamic measurement of hepatic function

A mathematical technique known as deconvolutional analysis was used to provide a critical and previously missing element in the computations required to quantitate hepatic function scintigraphically. This computer-assisted technique allowed for the determination of the time required, in minutes, of a labeled bilirubin analog (99mTc-disofenin) to enter the liver via blood and exit via bile. This interval was referred to as the mean transit time (MTT). The critical process provided for by deconvolution is the mathematical simulation of a bolus injection of tracer directly into the afferent blood supply of the liver. The raw data required for this simulation are obtained from the intravenous injection of labeled disofenin, a member of the HIDA family of radiopharmaceuticals. In this study, we perform experiments which document that the simulation process itself is accurate. We then calculate the MTT under a variety of experimental conditions involving progressive hepatic ischemia/reperfusion injury and correlate these results with the results of simultaneously performed BSP determinations and hepatic histology. The experimental group with the most pronounced histologic findings (necrosis, vacuolization, disorganization of hepatic cords) also have the most prolonged MTT and BSP half-life. However, both quantitative imaging and BSP testing are able to identify milder degrees of hepatic ischemic injury not reflected in the histologic evaluation. Quantitative imaging with deconvolutional analysis is a technique easily adaptable to the standard nuclear medicine minicomputer. It provides rapid results and appears to be a sensitive monitor of hepatic functional disturbances resulting from ischemia and reperfusion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26699/1/0000247.pd

Gradient nonlinearity effects on upper cervical spinal cord area measurement from 3D T-1-weighted brain MRI acquisitions

Purpose: To explore (i) the variability of upper cervical cord area (UCCA) measurements from volumetric brain 3D T1 -weighted scans related to gradient nonlinearity (GNL) and subject positioning; (ii) the effect of vendor-implemented GNL corrections; and (iii) easily applicable methods that can be used to retrospectively correct data. Methods: A multiple sclerosis patient was scanned at seven sites using 3T MRI scanners with the same 3D T1 -weighted protocol without GNL-distortion correction. Two healthy subjects and a phantom were additionally scanned at a single site with varying table positions. The 2D and 3D vendor-implemented GNL-correction algorithms and retrospective methods based on (i) phantom data fit, (ii) normalization with C2 vertebral body diameters, and (iii) the Jacobian determinant of nonlinear registrations to a template were tested. Results: Depending on the positioning of the subject, GNL introduced up to 15% variability in UCCA measurements from volumetric brain T1 -weighted scans when no distortion corrections were used. The 3D vendor-implemented correction methods and the three proposed methods reduced this variability to less than 3%. Conclusions: Our results raise awareness of the significant impact that GNL can have on quantitative UCCA studies, and point the way to prospectively and retrospectively managing GNL distortions in a variety of settings, including clinical environments. Magn Reson Med 79:1595-1601, 2018. © 2017 International Society for Magnetic Resonance in Medicine

Critical presentation of pleuropulmonary blastoma.

We report two cases of critical presentation of a quite rare lung neoplasm of childhood. Presentation findings were at the extremes of the clinical pattern of this polymorphous neoplasm, ranging from an enormous solid mass causing airway compression and dislocation to an apparently benign cystic lesion discovered because of a tension pneumothorax. Both children were discharged from the pediatric intensive care unit and underwent appropriate surgical removal and oncological management. Congenital lung cysts, even asymptomatic, should not be underestimated and need elective surgical excision and histologic examination

Effects of gingival curettage when performed 1 month after root instrumentation

. The purpose of the present study was to evaluate biometrically the periodontal response to gingival curettage. 15 subjects having suprabony pockets were selected. Gingival Index (GI) was initially determined for the selected teeth. Measurements of probing depth, and the distance from the free gingival margin to the cemento-enamel junction were also taken at that time, as well as immediately after scaling and root planing of the selected teeth. 4 weeks after scaling and root planing, the clinical parameters were recorded- A split mouth design was used to select 2 quadrants of the mouth in which gingival curettage was to be performed. Immediately after, experimental measurements were again recorded. 5 weeks after gingival curettage, gingival inflammation, probing depth and the location of the tree gingival margin were recorded for the last time. All data were analyzed statistically. It was shown that gingival inflammation, the distance from the free gingival margin to the cemento-enamel junction, and the probing depth were reduced after 4 and 9 weeks. The level of clinical attachment improved after 9 weeks. All these changes were statistically significant. These results were observed after scaling and root planing, as well as after scaling, root planing and gingival curettage. No differences were found between both treatment modalities in any of the parameters analyzed. Gingival curettage did not improve the condition of the periodontal tissues more significantly than scaling and root planing.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75160/1/j.1600-051X.1983.tb01276.x.pd