Prioritization Methodology for Chemical Replacement

This project serves to define an appropriate methodology for effective prioritization of efforts required to develop replacement technologies mandated by imposed and forecast legislation. The methodology used is a semiquantitative approach derived from quality function deployment techniques (QFD Matrix). This methodology aims to weigh the full environmental, cost, safety, reliability, and programmatic implications of replacement technology development to allow appropriate identification of viable candidates and programmatic alternatives. The results are being implemented as a guideline for consideration for current NASA propulsion systems

System engineering toolbox for design-oriented engineers

This system engineering toolbox is designed to provide tools and methodologies to the design-oriented systems engineer. A tool is defined as a set of procedures to accomplish a specific function. A methodology is defined as a collection of tools, rules, and postulates to accomplish a purpose. For each concept addressed in the toolbox, the following information is provided: (1) description, (2) application, (3) procedures, (4) examples, if practical, (5) advantages, (6) limitations, and (7) bibliography and/or references. The scope of the document includes concept development tools, system safety and reliability tools, design-related analytical tools, graphical data interpretation tools, a brief description of common statistical tools and methodologies, so-called total quality management tools, and trend analysis tools. Both relationship to project phase and primary functional usage of the tools are also delineated. The toolbox also includes a case study for illustrative purposes. Fifty-five tools are delineated in the text

Pressure Gradient Effects on Hypersonic Cavity Flow Heating

The effect of a pressure gradient on the local heating disturbance of rectangular cavities tested at hypersonic freestream conditions has been globally assessed using the two-color phosphor thermography method. These experiments were conducted in the Langley 31-Inch Mach 10 Tunnel and were initiated in support of the Space Shuttle Return-To-Flight Program. Two blunted-nose test surface geometries were developed, including an expansion plate test surface with nearly constant negative pressure gradient and a flat plate surface with nearly zero pressure gradient. The test surface designs and flow characterizations were performed using two-dimensional laminar computational methods, while the experimental boundary layer state conditions were inferred using the measured heating distributions. Three-dimensional computational predictions of the entire model geometry were used as a check on the design process. Both open-flow and closed-flow cavities were tested on each test surface. The cavity design parameters and the test condition matrix were established using the computational predictions. Preliminary conclusions based on an analysis of only the cavity centerline data indicate that the presence of the pressure gradient did not alter the open cavity heating for laminar-entry/laminar-exit flows, but did raise the average floor heating for closed cavities. The results of these risk-reduction studies will be used to formulate a heating assessment of potential damage scenarios occurring during future Space Shuttle flights

Ancient Pastoral Settlement in The Dhofar Mountains: Archaeological Excavations at Shakil and Halqoot

For much of Dhofar’s history and prehistory, most of its population has been mobile in search of wild game and with herded domesticated animals, which need new grass and browse. While few archaeological sites in the southern region of Oman suggest permanent or even semi-permanent occupations, there is now clear evidence of a distinct and perhaps unique episode of well-constructed, semi-permanent settlements in the Jebel Qāra, Dhofar. In 2012 and 2017, archaeological teams established a chronology, occupation history, and pastoralisthunter lifestyle of these settlements’ occupants, raising new questions about episodes of pastoralist settlement in long-term context. This paper documents the archaeological sites, their architectural details and layout, associated finds, and preliminary assessments of their faunal and vegetative components

Aero-Heating of Shallow Cavities in Hypersonic Freestream Flow

The purpose of these experiments and analysis was to augment the heating database and tools used for assessment of impact-induced shallow-cavity damage to the thermal protection system of the Space Shuttle Orbiter. The effect of length and depth on the local heating disturbance of rectangular cavities tested at hypersonic freestream conditions has been globally assessed using the two-color phosphor thermography method. These rapid-response experiments were conducted in the Langley 31-Inch Mach 10 Tunnel and were initiated immediately prior to the launch of STS-114, the initial flight in the Space Shuttle Return-To-Flight Program, and continued during the first week of the mission. Previously-designed and numerically-characterized blunted-nose baseline flat plates were used as the test surfaces. Three-dimensional computational predictions of the entire model geometry were used as a check on the design process and the two-dimensional flow assumptions used for the data analysis. The experimental boundary layer state conditions were inferred using the measured heating distributions on a no-cavity test article. Two test plates were developed, each containing 4 equally-spaced spanwise-distributed cavities. The first test plate contained cavities with a constant length-to-depth ratio of 8 with design point depth-to-boundary-layer-thickness ratios of 0.1, 0.2, 0.35, and 0.5. The second test plate contained cavities with a constant design point depth-to-boundary-layer-thickness ratio of 0.35 with length-to-depth ratios of 8, 12, 16, and 20. Cavity design parameters and the test condition matrix were established using the computational predictions. Preliminary results indicate that the floor-averaged Bump Factor (local heating rate nondimensionalized by upstream reference) at the tested conditions is approximately 0.3 with a standard deviation of 0.04 for laminar-in/laminar-out conditions when the cavity length-to-boundary-layer thickness is between 2.5 and 10 and for cavities in the depth-to-boundary-layer-thickness range of 0.3 to 0.8. Over this same range of conditions and parameters, preliminary results also indicate that the maximum Bump Factor on the cavity centerline falls between 2.0 and 2.75, as long as the cavity-exit conditions remain laminar. Cavities with length-to-boundary-layer-thickness ratio less than 2.5 can not be easily classified with this approach and require further analysis

Modulation of LISA free-fall orbits due to the Earth-Moon system

We calculate the effect of the Earth-Moon (EM) system on the free-fall motion of LISA test masses. We show that the periodic gravitational pulling of the EM system induces a resonance with fundamental frequency 1 yr^-1 and a series of periodic perturbations with frequencies equal to integer harmonics of the synodic month (9.92 10^-7 Hz). We then evaluate the effects of these perturbations (up to the 6th harmonics) on the relative motions between each test masses couple, finding that they range between 3mm and 10pm for the 2nd and 6th harmonic, respectively. If we take the LISA sensitivity curve, as extrapolated down to 10^-6 Hz, we obtain that a few harmonics of the EM system can be detected in the Doppler data collected by the LISA space mission. This suggests that the EM system gravitational near field could provide an absolute calibration for the LISA sensitivity at very low frequencies.Comment: 15 pages, 5 figure

A Gigantic Shark from the Lower Cretaceous Duck Creek Formation of Texas

Author Contributions Conceived and designed the experiments: JAF SNS JAD-F. Analyzed the data: JAF SNS. Wrote the paper: JAF SNS. Site data for OMNH V1727 are available by request from the department of vert. paleontology at the (SN)OMNH.Three large lamniform shark vertebrae are described from the Lower Cretaceous of Texas. We interpret these fossils as belonging to a single individual with a calculated total body length of 6.3 m. This large individual compares favorably to another shark specimen from the roughly contemporaneous Kiowa Shale of Kansas. Neither specimen was recovered with associated teeth, making confident identification of the species impossible. However, both formations share a similar shark fauna, with Leptostyrax macrorhiza being the largest of the common lamniform sharks. Regardless of its actual identification, this new specimen provides further evidence that large-bodied lamniform sharks had evolved prior to the Late Cretaceous.Ye

Tiny cystine stones in the gallbladder of a patient with cholecystolithiasis complicating acute cholecystitis: a case report

Cystine stones, the main component of which is cystine, are very common urinary calculi, but are rare in the gall bladder. In animals, there has been only one report of cystine gallstones in tree shrews, and to our knowledge, this is the first report of cystine gallstones in humans

Evolution of hepatic steatosis in patients with advanced hepatitis C: Results from the hepatitis C antiviral long-term treatment against cirrhosis (HALT-C) trial

Hepatic steatosis is a common histologic feature in patients with chronic hepatitis C (CHC) but there are no large longitudinal studies describing the progression of steatosis in CHC. We examined changes in steatosis on serial biopsies among CHC patients participating in the Hepatitis C Antiviral Long-term Treatment against Cirrhosis (HALT-C) Trial. All 1050 patients in the trial had advanced fibrosis at baseline biopsy and were documented not to have had a sustained virological response to peginterferon and ribavirin. Most (94%) patients had genotype 1 infection. At least one protocol follow-up biopsy was read on 892 patients, and 699 had the last biopsy performed 3.5 years after randomization. At enrollment, 39% had cirrhosis and 61% had bridging fibrosis; 18%, 41%, 31%, and 10% had steatosis scores of 0, 1, 2, and 3 or 4, respectively. The mean steatosis score decreased in the follow-up biopsies in both the interferon-treated patients and controls with no effect of treatment assignment ( P = 0.66). A decrease in steatosis score by ≥1 point was observed in 30% of patients and was associated with both progression to cirrhosis and continued presence of cirrhosis ( P = 0.02). Compared to patients without a decrease in steatosis, those with a decrease in steatosis had worse metabolic parameters at enrollment, and were more likely to have a decrease in alcohol intake, improvement in metabolic parameters, and worsening liver disease (cirrhosis, esophageal varices, and deterioration in liver function). Conclusion: Serial biopsies demonstrated that in patients with CHC, steatosis recedes during progression from advanced fibrosis to cirrhosis. Decreased alcohol intake and improved metabolic parameters are associated with a decline in steatosis and may modulate hepatitis C progression. (H EPATOLOGY 2009.)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63058/1/22865_ftp.pd