3,010 research outputs found
Technology transfer needs and experiences: The NASA Research Center perspective
Viewgraphs on technology transfer needs and experiences - the NASA Research Center perspective are provided. Topics covered include: functions of NASA, incentives and benefits, technology transfer mechanisms, economics of technology commercialization, examples, and conclusions
Yesterday, today and tomorrow: A perspective of CFD at NASA's Ames Research Center
The opportunity to reflect on the computational fluid dynamics (CFD) progam at the NASA Ames Research Center (its beginning, its present state, and its direction for the future) is afforded. Essential elements of the research program during each period are reviewed, including people, facilities, and research problems. The burgeoning role that CFD is playing in the aerospace business is discussed, as is the necessity for validated CFD tools. The current aeronautical position of this country is assessed, as are revolutionary goals to help maintain its aeronautical supremacy in the world
Progress and future directions in computational fluid dynamics
Computational fluid dynamics (CFD) has made great strides in the detailed simulation of complex fluid flows, including the fluid physics of flows heretofore not understood. It is now being routinely applied to some rather complicated problems, and starting to impact the design cycle of aerospace vehicles and their components. In addition, it is being used to complement and is being complemented by experimental studies. In this paper some major elements of contemporary CFD research, such as code validation, turbulence physics, and hypersonic flows are discussed, along with a review of the principal pacing items that currently govern CFD. Several examples are presented to illustrate the current state of the art. Finally, prospects for the future of the development and application of CFD are suggested
Analysis of Space Shuttle Ground Support System Fault Detection, Isolation, and Recovery Processes and Resources
As part of the FDIR (Fault Detection, Isolation, and Recovery) Project for the Constellation Program, a task was designed within the context of the Constellation Program FDIR project called the Legacy Benchmarking Task to document as accurately as possible the FDIR processes and resources that were used by the Space Shuttle ground support equipment (GSE) during the Shuttle flight program. These results served as a comparison with results obtained from the new FDIR capability. The task team assessed Shuttle and EELV (Evolved Expendable Launch Vehicle) historical data for GSE-related launch delays to identify expected benefits and impact. This analysis included a study of complex fault isolation situations that required a lengthy troubleshooting process. Specifically, four elements of that system were considered: LH2 (liquid hydrogen), LO2 (liquid oxygen), hydraulic test, and ground special power
Thoroughness of Mediastinal Staging in Stage IIIA Non-small Cell Lung Cancer
IntroductionGuidelines recommend that patients with clinical stage IIIA non-small cell lung cancer (NSCLC) undergo histologic confirmation of pathologic lymph nodes. Studies have suggested that invasive mediastinal staging is underutilized, although practice patterns have not been rigorously evaluated.MethodsWe used the Surveillance, Epidemiology, and End Results-Medicare database to identify patients with stage IIIA NSCLC diagnosed from 1998 through 2005. Invasive staging and use of positron emission tomography (PET) scanning were assessed using Medicare claims. Multivariable logistic regression was used to identify patient characteristics associated with use of invasive staging.ResultsOf 7583 stage IIIA NSCLC patients, 1678 (22%) underwent invasive staging. Patients who received curative intent cancer treatment were more likely to undergo invasive staging than patients who did not receive cancer-specific therapy (30% versus 9.8%, adjusted odds ratio, 3.31; 95% confidence interval, 2.78–3.95). The oldest patients (age, 85–94 years) were less likely to receive invasive staging than the youngest (age, 67–69 years; 27.6% versus 11.9%; odds ratio, 0.46; 95% confidence interval, 0.34–0.61). Sex, marital status, income, and race were not associated with the use of the invasive staging. The use of invasive staging was stable throughout the study period, despite an increase in the use of PET scanning from less than 10% of patients before 2000 to almost 70% in 2005.ConclusionNearly 80% of Medicare beneficiaries with stage IIIA NSCLC do not receive guideline adherent mediastinal staging; this failure cannot be entirely explained by patient factors or a reliance on PET imaging. Incentives to encourage use of invasive staging may improve care
Josephson effect between trapped Bose-Einstein condensates
We study the Josephson effect between atomic Bose-Einstein condensates. By
drawing on an electrostatic analogy, we derive a semiclassical functional
expression for the three-dimensional Josephson coupling energy in terms of the
condensate density. Estimates of the capacitive energy and of the Josephson
plasma frequency are also given. The effect of dissipation due to the
incoherent exchange of normal atoms is analysed. We conclude that coherent
Josephson dynamics may already be observable in current experimental systems.Comment: 4 pages, RevTe
Macroscopic Quantum Tunneling of a Bose-Einstein Condensate with Attractive Interaction
A Bose-Einstein condensate with attractive interaction can be metastable if
it is spatially confined and if the number of condensate bosons is below
a certain critical value . By applying a variational method and the
instanton techinique to the Gross-Pitaevskii energy functional, we find
analytically the frequency of the collective excitation and the rate of
macroscopic quantum tunneling (MQT). We show that near the critical point the
tunneling exponent vanishes according to and that MQT
can be a dominant decay mechanism of the condensate for very close to
.Comment: RevTex 4 pages with 1 postscript figure. Accepted for publication in
Physical Review Letter
Charge Symmetry Breaking in the Valence Quark Distributions of the Nucleon
Using a quark model, we study the effect of charge symmetry breaking on the
valence quark distributions of the nucleon. The effect due to quark mass
differences and the Coulomb interaction of the electrically charged quarks is
calculated and, in contrast to recent claims, found to be small. In addition,
we investigate the effect of charge symmetry breaking in the confining
interaction, and in the perturbative evolution equations used to relate the
quark model distributions to experiment. We find that both these effects are
small, and that the strong charge symmetry breaking effect included in the
scalar confining interactions may be distinguishable from that generated by
quark mass differences.Comment: 10 pages, LaTEX, 5 Postscript figure
Leading and higher twists in the proton polarized structure function at large Bjorken x
A phenomenological parameterization of the proton polarized structure
function has been developed for x > 0.02 using deep inelastic data up to ~ 50
(GeV/c)**2 as well as available experimental results on both photo- and
electro-production of proton resonances. According to the new parameterization
the generalized Drell-Hearn-Gerasimov sum rule is predicted to have a
zero-crossing point at Q**2 = 0.16 +/- 0.04 (GeV/c)**2. Then, low-order
polarized Nachtmann moments have been estimated and their Q**2-behavior has
been investigated in terms of leading and higher twists for Q**2 > 1
(GeV/c)**2. The leading twist has been treated at NLO in the strong coupling
constant and the effects of higher orders of the perturbative series have been
estimated using soft-gluon resummation techniques. In case of the first moment
higher-twist effects are found to be quite small for Q**2 > 1 (GeV/c)**2, and
the singlet axial charge has been determined to be a0[10 (GeV/c)**2] = 0.16 +/-
0.09. In case of higher order moments, which are sensitive to the large-x
region, higher-twist effects are significantly reduced by the introduction of
soft gluon contributions, but they are still relevant at Q**2 ~ few (GeV/c)**2
at variance with the case of the unpolarized transverse structure function of
the proton. Our finding suggests that spin-dependent correlations among partons
may have more impact than spin-independent ones. As a byproduct, it is also
shown that the Bloom-Gilman local duality is strongly violated in the region of
polarized electroproduction of the Delta(1232) resonance.Comment: revised version to appear in Phys. Rev. D; extended discussion on the
generalized DHG sum rul
Assessing estrogen-induced proliferative response in an endometrial cancer cell line using a universally applicable methodological guide
Objective: Translational endometrial cancer (EC) research benefits from an in vitro experimental approach using EC cell lines. We demonstrated the steps that are required to examine estrogen induced proliferative response, a simple yet important research question pertinent to EC and devised a pragmatic methodological workflow for utilising EC cell lines in experimental models. Methods/materials: Comprehensive review of all commercially available EC cell lines was carried out, and Ishikawa cell line was selected to study the oestrogen responsiveness with HEC1A, RL95-2 and MFE280 cell lines as comparators where appropriate, examining relevant differential molecular (steroid receptors) and functional (phenotype, anchorage-independent growth, hormone responsiveness, migration, invasion and chemosensitivity) characteristics in 2D and 3D cultures in vitro using immunocytochemistry, immunofluorescence, qPCR and western blotting. In vivo tumour, formation and chemosensitivity were also assessed in a chick chorioallantoic membrane (CAM) model. Results: Short Tandem Repeat (STR) analysis authenticated the purchased cell lines while gifted cells deviated significantly from the published profile. We demonstrate the importance of prior assessment of the suitability of each cell line for the chosen in vitro experimental technique. Prior establishment of baseline, non-enriched conditions was required to induce a proliferative response to estrogen. The CAM model was a suitable in vivo multi-cellular animal model for EC, for producing rapid and reproducible data. Conclusions: We have developed a methodological guide for EC researchers when using endometrial cell lines to answer important translational research questions (exemplified by estrogen responsive cell proliferation), to facilitate robust data, while saving time and resources
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