A scanning electron microscopy study of the macro-crystalline structure of 2-(2,4-dinitrobenzyl) pyridine

The compound, 2-(2,4-dinitrobenzyl) pyridine, was synthesized in the laboratory; an introductory level electron microscopy study of the macro-crystalline structure was conducted using the scanning electron microscope (SEM). The structure of these crystals was compared with the macrostructure of the crystal of 2-(2,4-dinitrobenzyl) pyridinium bromide, the hydrobromic salt of the compound which was also synthesized in the laboratory. A scanning electron microscopy crystal study was combined with a study of the principle of the electron microscope

Subsonic aerodynamic characteristics of a proposed advanced manned launch system orbiter configuration

The Advanced Manned Launch System is a proposed near-term technology, two-stage, fully reusable launch system that consists of an unmanned glide-back booster and a manned orbiter. An orbiter model that featured a large fuselage and an aft delta wing with tip fins was tested in the Langley 7- by 10-Foot High-Speed Tunnel. A crew cabin, large payload fairing, and crew access tunnel were mounted on the upper body. The results of the investigation indicated that the configuration was longitudinally stable to an angle of attack of about 6 deg about a center-of-gravity position of 0.7 body length. The model had an untrimmed lift-drag ratio of 6.6, but could not be trimmed at positive lift. The orbiter model was also directionally unstable. The payload fairing was responsible for about half the instability. The tip-fin controllers, which are designed as active controls to produce artificial directional stability, were effective in producing yawing moment, but sizable adverse rolling moment occurred at angles of attack above 6 deg. Differential deflection of the elevon surfaces was effective in producing rolling moment with only small values of adverse yawing moment

INVESTIGATION OF THE LOW-SUBSONIC STABILITY AND CONTROL CHARACTERISTICS OF A 0.34 -SCALE FREE-FLYING MODEL OF A MODIFIED HALF-CONE REENTRY VEHICLE

Low subsonic stability and control of a 0.34-scale free flying model of a half cone reentry vehicl

Identifying populations at risk: functional impairment and emotional distress

Presentation at the 2002 Medical Director Colloquy, Tucson, Ariz., May 16–18. Title of Managed Care supplement: Multidisciplinary Management of Dyslipidemia

In re Cheeseman: A Judicial Revision of Virginia\u27s Homestead Exemption Laws

The Bankruptcy Reform Act of 1978 was the first major revision of federal bankruptcy law in over forty years. An important goal of the Act is to provide the debtor with a meaningful fresh start. To that end, the Bankruptcy Act provides liberalized allowances in amounts and types of property that a debtor may hold exempt from creditors in an insolvency proceeding. Under section 522 subsection (b) of the Act, however, a state is permitted to opt out of the federal exemption scheme and prescribe under its own law the exemptions a debtor may claim. Virginia is among those states which have chosen to opt out of the federal scheme

Pilot cryo tunnel: Attachments, seals, and insulation

Several different tests are described which simulated the actual configuration of a cryogenic wind tunnel operating at pressures up to 5 atmospheres (507 kPa) and temperatures from -320 F (78K) to 120 F (322K) in order to determine compatible bolting, adequate sealing, and effective insulating materials. The evaluation of flange attachments (continuous threaded studs) considered bolting based on compatible flanges, attachment materials, and prescribed bolt elongations. Various types of seals and seal configurations were studied to determine suitability and reusability under the imposed pressure and temperature loadings. The temperature profile was established for several materials used for structural supports

Using bootstrap to compare the validity of PRO measures in discriminating among CKD patients

BACKGROUND: Patient-reported outcome (PRO) research requires valid and sensitive measures. Relative Validity (RV) offers an objective way to compare the validity of different PRO measures in discriminating groups of patients or occasions. There is no significance test associated with RV. We applied bootstrap to estimate the confidence interval (CI) of RV to better interpret the differences in RV. METHODS: The CKD-specific legacy (KDQOL Burden, Symptom, and Effect), generic health scales (SF-12), and Kidney Disease Impact Scale (KDIS) were administrated to 453 CKD patients. ANOVA-based RV coefficients were computed to compare how well each scale discriminated between three clinically-defined severity groups (Dialysis \u3e Stage 3-5 \u3e Transplant). Bootstrap was used to construct CI to determine whether the differences in RV were significant in comparisons between each scale and the best legacy standard- KDQOL Burden. Factors of sample size, number of bootstrap replications, bootstrap method were varied to investigate their impacts. RESULTS: In comparison with KDQOL Burden (RV=1), using 95% CI, differences were non-significant for KDIS (RV=1.13), KDQOL Effect (RV=.99), SF-12 RP (RV=.77) and PF (RV=.70). SF-12 PCS (RV=.60) was at borderline. The other measures were significantly poorer in discriminating the patients. Sample size played a substantial role. 300 patients for 3 groups greatly reduced the standard errors compared to 100 patients. A larger sample size greatly increased the power of detecting the differences. The number of replications did not have consequential influence. The types of BCa and percentile intervals were preferred as all bootstrap distributions were skewed. The magnitude of chosen standard measure’s F-statistics appeared to have a noticeable impact on CI too. CONCLUSIONS: Bootstrapping appears to be valuable in comparing the validity of PRO measures from a statistical perspective. The significance test of RV was affected by the sample size, magnitude of RV, and F-statistic of standard measure

Surface roughness effects on the supersonic aerodynamics of the Rockwell International 089B-139 orbiter

An experimental test program was conducted to determine the effects of vehicle surface roughness on the supersonic aerodynamic characteristics of a 0.01875 scale model of a space shuttle configuration. Surface roughness was simulated by applying a sparse coating of carborundum grit to complete model. Various grit sizes were investigated. The tests were conducted in a wind tunnel at Mach numbers from 1.60 to 4.63. The angle of attack was varied from about -2 deg to as much as 42 deg at 0 deg and + or - 3 deg of sideslip. The angle of sideslip was varied from -8 deg to 8 deg at angles of attack from 0 deg to 40 deg