Investigation of cavitation damage of a mechanical pump impeller in high temperature potassium quarterly progress report no. 1, 7 dec. 1964 - 28 feb. 1965

Cavitation damage prediction from mixed flow centrifugal pump impeller in endurance testing in high temperature potassiu

NASA contract listings of publications under the behavioral biology program

Behavioral biology - bibliograph

The results of the in-flight attitude sensor calibration for the Arthur Holly Compton Gamma Ray Observatory

The Arthur Holly Compton Gamma Ray Observatory (GRO) was launched by the shuttle Atlantis in April 1991. This paper presents the results of the attitude sensor calibration that was performed during the early mission. The GSFC Flight Dynamics Facility (FDF) performed an alignment calibration of the two fixed-head star trackers (FHST's) and two fine Sun sensors (FSS's) on board Compton GRO. The results show a 27-arcsecond shift between the bore sights of the FHST's with respect to prelaunch measurements. The alignments of the two FSS's shifted by 0.20 and 0.05 degree. During the same time period, the Compton GRO science teams performed an alignment calibration of the science instruments with respect to the attitude reported by the on board computer (OBC). In order to preserve these science alignments, FDF adjusted the overall alignments of the FHST's and FSS's, obtained by the FDF calibration, such that when up linked to the OBC, the shift in the OBC-determined attitude is minimized. FDF also calibrated the inertial reference unit (IRU), which consists of three dual-axis gyroscopes. The observed gyro bias matched the bias that was solved for by the OBC. This bias drifted during the first 6 days after release. The results of the FDF calibration of scale factor and alignment shifts showed changes that were of the same order as their uncertainties

Control of Integrable Hamiltonian Systems and Degenerate Bifurcations

We discuss control of low-dimensional systems which, when uncontrolled, are integrable in the Hamiltonian sense. The controller targets an exact solution of the system in a region where the uncontrolled dynamics has invariant tori. Both dissipative and conservative controllers are considered. We show that the shear flow structure of the undriven system causes a Takens-Bogdanov birfurcation to occur when control is applied. This implies extreme noise sensitivity. We then consider an example of these results using the driven nonlinear Schrodinger equation.Comment: 25 pages, 11 figures, resubmitted to Physical Review E March 2004 (originally submitted June 2003), added content and reference

Search for Intrinsic Excitations in 152Sm

The 685 keV excitation energy of the first excited 0+ state in 152Sm makes it an attractive candidate to explore expected two-phonon excitations at low energy. Multiple-step Coulomb excitation and inelastic neutron scattering studies of 152Sm are used to probe the E2 collectivity of excited 0+ states in this "soft" nucleus and the results are compared with model predictions. No candidates for two-phonon K=0+ quadrupole vibrational states are found. A 2+, K=2 state with strong E2 decay to the first excited K=0+ band and a probable 3+ band member are established.Comment: 4 pages, 6 figures, accepted for publication as a Rapid Communication in Physical Review

In vivo testing of novel vaccine prototypes against Actinobacillus pleuropneumoniae

Actinobacillus pleuropneumoniae (A. pleuropneumoniae) is a Gram-negative bacterium that represents the main cause of porcine pleuropneumonia in pigs, causing significant economic losses to the livestock industry worldwide. A. pleuropneumoniae, as the majority of Gram-negative bacteria, excrete vesicles from its outer membrane (OM), accordingly defined as outer membrane vesicles (OMVs). Thanks to their antigenic similarity to the OM, OMVs have emerged as a promising tool in vaccinology. In this study we describe the in vivo testing of several vaccine prototypes for the prevention of infection by all known A. pleuropneumoniae serotypes. Previously identified vaccine candidates, the recombinant proteins ApfA and VacJ, administered individually or in various combinations with the OMVs, were employed as vaccination strategies. Our data show that the addition of the OMVs in the vaccine formulations significantly increased the specific IgG titer against both ApfA and VacJ in the immunized animals, confirming the previously postulated potential of the OMVs as adjuvant. Unfortunately, the antibody response raised did not translate into an effective protection against A. pleuropneumoniae infection, as none of the immunized groups following challenge showed a significantly lower degree of lesions than the controls. Interestingly, quite the opposite was true, as the animals with the highest IgG titers were also the ones bearing the most extensive lesions in their lungs. These results shed new light on A. pleuropneumoniae pathogenicity, suggesting that antibody-mediated cytotoxicity from the host immune response may play a central role in the development of the lesions typically associated with A. pleuropneumoniae infections

Carbon choices determine US cities committed to futures below sea level

Anthropogenic carbon emissions lock in long-term sea-level rise that greatly exceeds projections for this century, posing profound challenges for coastal development and cultural legacies. Analysis based on previously published relationships linking emissions to warming and warming to rise indicates that unabated carbon emissions up to the year 2100 would commit an eventual global sea-level rise of 4.3–9.9 m. Based on detailed topographic and population data, local high tide lines, and regional long-term sea-level commitment for different carbon emissions and ice sheet stability scenarios, we compute the current population living on endangered land at municipal, state, and national levels within the United States. For unabated climate change, we find that land that is home to more than 20 million people is implicated and is widely distributed among different states and coasts. The total area includes 1,185–1,825 municipalities where land that is home to more than half of the current population would be affected, among them at least 21 cities exceeding 100,000 residents. Under aggressive carbon cuts, more than half of these municipalities would avoid this commitment if the West Antarctic Ice Sheet remains stable. Similarly, more than half of the US population-weighted area under threat could be spared. We provide lists of implicated cities and state populations for different emissions scenarios and with and without a certain collapse of the West Antarctic Ice Sheet. Although past anthropogenic emissions already have caused sea-level commitment that will force coastal cities to adapt, future emissions will determine which areas we can continue to occupy or may have to abandon

Mapping Choices: Carbon, Climate, and Rising Seas: Our Global Legacy

Carbon emissions causing 4 degrees Celsius of warming (7.2 degrees Fahrenheit) — a business-asusual scenario — could lock in enough eventual sea level rise to submerge land currently home to 470 to 760 million people globally. Carbon cuts resulting in the proposed international target of 2 °C warming (3.6 °F) would reduce the rise locked in so that it would threaten areas now occupied by as few as 130 million people. This contrast is one expression of what is at stake in the December 2015 global climate talks in Paris. This report builds closely on a paper first published online in October 2015 in the Proceedings of the National Academy of Sciences of the United States of America by the same authors. That research used relationships between cumulative carbon emissions, warming, and the future global sea level rise they lock in to assess implications for the United States and its cities. What distinguishes the current report is its application of sea level projections to global elevation, tidal, population, and administrative boundary data, instead of U.S. data only. Among all nations, this report finds that China has the most to lose from business as usual, with 145 million citizens today on implicated land. China also has the most to gain from limiting warming to 2 °C, which would cut the total to 64 million. Twelve other nations have more than 10 million people living on implicated land under 4 °C warming — India, Bangladesh, Viet Nam, Indonesia, Japan, the United States, Philippines, Egypt, Brazil, Thailand, Myanmar, and the Netherlands, in descending order of total threats. A carbon path that limits warming to 2 °C would reduce exposure by more than 10 million in each listed nation except the last two, and by half or more in all listed nations but Viet Nam (still achieving 44% reduction), Brazil (45%) and the Netherlands (13%). Global megacities with the top ten populations in the balance include Shanghai, Hong Kong, Calcutta, Mumbai, Dhaka, Jakarta, and Hanoi. 4 °C warming could lead to submergence of land inhabited by more than half the population of Shanghai, Mumbai and Hanoi, among these. These results are based on median sea level rise projections. They are also based on global elevation data with a tendency to understate exposure. Carbon emissions this century can lock in these projected threats, but the associated sea level rise is expected to play out over a longer period, likely centuries. This report assesses and lists global nations and urban agglomerations at risk by projected total population exposure, percent exposure, and differences in exposure under warming scenarios of 1.5, 2, 3 and 4 °C (2.7, 3.6, 5.4 and 7.2 °F). Results do not account for present or future shoreline defenses, such as levees, that might be built, nor for future population growth, decline or relocation. In conjunction with this report, Climate Central has extended its interactive and embeddable Mapping Choices platform globally (choices.climatecentral.org). Users can now type in any coastal city name or postal code worldwide, and visually compare the potential consequences of different warming or emissions scenarios on a local map. Climate Central is also serving Google Earth layers for visualizing sea levels associated with 2 °C or 4 °C warming in areas with 3-D building data, available here; and offering spreadsheets for download with analytic results for comprehensive lists of global nations and coastal urban agglomerations, available here