13 research outputs found
Space Shuttle Body Flap Actuator Bearing Testing for NASA Return to Flight
The Space Shuttle body flap is located beneath the main engine nozzles and is required for proper aerodynamic control during orbital descent. Routine inspection of one of four body flap actuators found one of the actuator bearings had degraded and blackened balls. A test program was initiated to demonstrate that it is acceptable to operate bearings which are degraded from operation over several flights. This test exposed the bearing to predicted flight axial loads, speeds and temperatures. Testing at 140 F has been completed, and results indicate the previously flown bearings are acceptable for up to 12 additional missions. Additional testing is underway to determine the lubricant life at various temperatures and stresses and to further understand the mechanism that caused the blacken balls. Initial results of this testing indicates that bearing life is shorten at room temperature possibly due fact that higher temperature (140 F) accelerates the flow of grease and oil into the wear surfac
Probabilistic Analysis of Space Shuttle Body Flap Actuator Ball Bearings
A probabilistic analysis, using the 2-parameter Weibull-Johnson method, was performed on experimental life test data from space shuttle actuator bearings. Experiments were performed on a test rig under simulated conditions to determine the life and failure mechanism of the grease lubricated bearings that support the input shaft of the space shuttle body flap actuators. The failure mechanism was wear that can cause loss of bearing preload. These tests established life and reliability data for both shuttle flight and ground operation. Test data were used to estimate the failure rate and reliability as a function of the number of shuttle missions flown. The Weibull analysis of the test data for the four actuators on one shuttle, each with a 2-bearing shaft assembly, established a reliability level of 96.9 percent for a life of 12 missions. A probabilistic system analysis for four shuttles, each of which has four actuators, predicts a single bearing failure in one actuator of one shuttle after 22 missions (a total of 88 missions for a 4-shuttle fleet). This prediction is comparable with actual shuttle flight history in which a single actuator bearing was found to have failed by wear at 20 missions
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
Realignment and the process of change at the Naval Postgraduate School
MBA Professional ReportFew studies have focused on the effects of change within a military graduate institution where military and academic subcultures coexist. This research focused on the 2001 organizational change at the Naval Postgraduate School. The purpose was to identify how change was approached and implemented. Our analysis revealed that this change process implemented across the organization affected the intensity of sub-cultural conflict within the organization. In the case of NPS, we found that an authoritarian military style of change negatively impacted the existing academic subculture. The pressure of a change effort that was not representative of both subcultures served to increase the intensity of conflict between the military and academic subcultures, thus jeopardizing the ability for the two to work together. This study contributes to and amplifies existing theory through the examination of organizational change in a unique military/academic environment. It is important for change agents to understand how these factors are interrelated so that the intensity of cultural conflict can be better managed.http://archive.org/details/realignmentndpro109459825Lieutenant, United States NavyLieutenant Commander, United States NavyApproved for public release; distribution is unlimited
Worksets expand the scholarly utility of digital libraries
Scholars using digital libraries and archives routinely create worksets-aggregations of digital objects-as a way to segregate resources of interest for in-depth scrutiny. To illustrate how worksets can enhance the scholarly utility of digital library content, we distill from prior user studies three key objectives for worksets (extra-digital library manipulation, intra-item properties, and robust representations), and discuss how they motivated the workset model being developed at the HathiTrust Research Center (HTRC). We describe how HTRC's implementation of its RDF-compliant workset model helps to satisfy these objectives
Selective filling of nanowells in nanowell arrays fabricated using polystyrene nanosphere lithography with cytochrome P450 enzymes
Bibliographic Ontologies Comparative Features Dataset
This spreadsheet provides a column-wise comparison of four leading RDF-based bibliographic vocabularies: MODS/MADS RDF, BIBFRAME, Schema.org and FRBRoo. The data demonstrates areas of alignment among the ontologies with regards to equivalent entities, properties, or groupings thereof.Mellon Reference Number 21300666Ope
Measurement of Electron Transfer through Cytochrome P450 Protein on Nanopillars and the Effect of Bound Substrates
Electron
transfer in cytochrome P450 enzymes is a fundamental process
for activity. It is difficult to measure electron transfer in these
enzymes because under the conditions typically used they exist in
a variety of states. Using nanotechnology-based techniques, gold conducting
nanopillars were constructed in an indexed array. The P450 enzyme
CYP2C9 was attached to each of these nanopillars, and conductivity
measurements made using conducting probe atomic force microscopy under
constant force conditions. The conductivity measurements were made
on CYP2C9 alone and with bound substrates, a bound substrate–effector
pair, and a bound inhibitor. Fitting of the data with the Poole–Frenkel
model indicates a correlation between the barrier height for electron
transfer and the ease of CYP2C9-mediated metabolism of the bound substrates,
though the spin state of iron is not well correlated. The approach
described here should have broad application to the measurement of
electron transfer in P450 enzymes and other metalloenzymes
A Phase II NCCTG Study of Irinotecan and Docetaxel in Previously Treated Patients with Non-Small Cell Lung Cancer.
PURPOSE: This Phase II study was undertaken to define the efficacy and toxicity of the combination of docetaxel and irinotecan for the second-line treatment of non-small cell lung cancer (NSCLC).
PATIENTS AND METHODS: Forty-six patients with measurable NSCLC who had relapsed after an initial response to chemotherapy or who had failed to respond to initial chemotherapy, received 130 mg/m2 of irinotecan IV over 90 minutes and 50 mg/m2 docetaxel IV over 60 minutes on Day 1 q3 weeks for 6 cycles. Dexamethasone and diphenhydramine pretreatment were given. Response to treatment was evaluated by response evaluation criteria in solid tumors RECIST criteria, and toxicity was graded according to the National Cancer Institute Common Toxicity Criteria (NCI CTC) version 2.0.
RESULTS: The most common severe (NCI CTC Grade 3+) adverse events were neutropenia (67 percent), diarrhea (28 percent), fatigue (20 percent), nausea (17 percent), infection (15 percent), vomiting (13 percent), leucopenia (13 percent), abdominal pain (11 percent), and dyspnea (11 percent). Grade 5 toxic events were seen in 2 patients. One of these 2 cases was a possibly-treatment related event (intestinal fistula). The median number of treatment cycles received was 3. Twelve patients (26 percent) received all 6 cycles of treatment. Five patients (11 percent) had a confirmed response (complete response (CR), partial response (PR), or regression). Median follow-up for the five surviving patients is 26.5 months (range: 25.1-28.4). Forty-two patients have reported progressive disease and 41 patients have died. Median time-to-progression (TTP) and survival are 2.6 months and 7.5 months, respectively.
CONCLUSION: This second-line treatment regimen of irinotecan and docetaxel in NSCLC patients has shown activity, but can not be recommended over single-agent regimens because of significant toxicity