Supersonic aeroelastic instability results for a NASP-like wing model

An experimental study and an analytical study have been conducted to examine static divergence for hypersonic-vehicle wing models at supersonic conditions. A supersonic test in the Langley Unitary Plan Wind Tunnel facility was conducted for two wind-tunnel models. These models were nearly identical with the exception of airfoil shape. One model had a four-percent maximum thickness airfoil and the other model had an eight-percent maximum thickness airfoil. The wing models had low-aspect ratios and highly swept leading edges. The all-movable wing models were supported by a single-pivot mechanism along the wing root. For both of the wind-tunnel models, configuration changes could be made in the wing-pivot location along the wing root and in the wing-pivot pitch stiffness. Three divergence conditions were measured for the four-percent thick airfoil model in the Mach number range of 2.6 to 3.6 and one divergence condition was measured for the eight-percent thick airfoil model at a Mach number of 2.9. Analytical divergence calculations were made for comparison with experimental results and to evaluate the parametric effects of wing-pivot stiffness, wing-pivot location, and airfoil thickness variations. These analyses showed that decreasing airfoil thickness, moving the wing-pivot location upstream, or increasing the pitch-pivot stiffness have the beneficial effect of increasing the divergence dynamic pressures. The calculations predicted the trend of experimental divergence dynamic pressure with Mach number accurately; however, the calculations were approximately 25 percent conservative with respect to dynamic pressure

Influence of polymer size on uptake and cytotoxicity of doxorubicin-loaded DNA–PEG conjugates

Intercalation of drugs into assembled DNA systems offers versatile new mechanisms for controlled drug delivery. However, current systems are becoming increasingly complex, reducing the practicality of large scale production. Here, we demonstrate a more pragmatic approach where a short DNA sequence was modified with poly(ethylene glycol) (PEG) of various lengths at both 5′-termini to provide serum stability and compatibility. The anticancer drug doxorubicin was physically loaded into two designed binding sites on the dsODN. The polymer conjugation improved the stability of the dsODN toward serum nucleases while its doxorubicin binding affinity was unaffected by the presence of the polymers. We examined the effects of polymer size on the dsODN carrier characteristics and studied the resulting DOX@DNA–PEG systems with respect to cytotoxicity, cellular uptake, and localization in A549 and MCF7 cell lines. For the A549 cell line the DOX@DNA-PEG1900 exhibited the best dose response of the conjugates while DOX@DNA-PEG550 was the least potent. In MCF-7, a more doxorubicin sensitive cell line, all conjugates exhibited similar dose response to that of the free drug. Confocal microscopy analysis of doxorubicin localization shows that conjugates successfully deliver doxorubicin to the cell nucleus and also the lysosome. These data provide a valuable insight into the complexities of designing an oligonucleotide based drug delivery system and highlight some practical issues that need to be considered when doing so

Atmospheric bromoform at Mace Head, Ireland: Evidence for a peatland source

International audienceIn situ atmospheric observations of bromoform (CHBr3) made over a 2.5 year period at Mace Head, Ireland from May 2001?December 2003, including during the NAMBLEX (North Atlantic Marine Boundary Layer Experiment) campaign, show broad maxima from spring until autumn and winter minima, with mixing ratios of 5.3+1.0 pptv (mid March?mid October) and 1.8+0.8 pptv (December?February). This indicates that, unlike CHCl3, which has a summer minimum and winter maximum at Mace Head, local biological sources of CHBr3 have a greater influence on the atmospheric data than photochemical decay during long-range transport. The emission sources are predominantly macroalgal, but we find evidence for a small terrestrial flux from peatland ecosystems, which so far has not been accounted for in the CHBr3 budget. Sharp increases in CHCl3 and CHBr3 concentrations and decreases in O3 concentrations occurred at night when the wind direction switched from an ocean- to a land-based sector (land breeze) and the wind speed dropped to below 5 ms?1. These observations infer a shallow atmospheric boundary layer with increased O3 deposition and concentration of local emissions of both CHCl3 and CHBr3. The ratio of ?CHCl3/?CHBr3 varied strongly according to the prevailing wind direction; from 0.6+0.1 in south-easterly (100?170°) air to 1.9+0.8 in north-easterly (40?70°) air. Of these land-sectors, the south-easterly air masses are likely to be strongly influenced by macroalgal beds along the coast and the emission ratios probably reflect those from seaweeds in addition to land sources. The north-easterly airmasses however have a fetch predominantly over land, which locally is comprised of coastal peatland ecosystems (peat bogs and coastal conifer plantations), previously identified as being strong sources of atmospheric CHCl3 under these conditions. Although we cannot entirely rule out other local land or coastal sources, our observations also suggest peatland ecosystem emissions of CHBr3. We use correlations between CHCl3 and CHBr3 during the land breeze events in conjunction with previous estimates of local wetland CHCl3 release to tentatively deduce a global wetland CHBr3 source of 26.9 (0.5?1247) Gg yr?1, which is approximately 10% of the total global source

Atmospheric bromoform at Mace Head, Ireland: seasonality and evidence for a peatland source

In situ atmospheric observations of bromoform (CHBr₃) made over a 2.5 year period at Mace Head, Ireland from May 2001- Dec 2003, including during the NAMBLEX (North Atlantic Marine Boundary Layer Experiment) campaign, show broad maxima from spring until autumn and winter minima, with mixing ratios of 5.3+1.0 pptv (mid March - mid October) and 1.8+0.8 pptv (December-February). This indicates that, unlike CHCl₃, which has a summer minimum and winter maximum at Mace Head, local biological sources of CHBr₃ have a greater influence on the atmospheric data than photochemical decay during long-range transport. The emission sources are predominantly macroalgal, but we find evidence for a small terrestrial flux from peatland ecosystems, which so far has not been accounted for in the CHBr₃ budget. Sharp increases in CHCl₃ and CHBr₃ concentrations and decreases in O₃ concentrations occurred at night when the wind direction switched from an ocean- to a land-based sector (land breeze) and the wind speed dropped to below 5 ms^-1. These observations infer a shallow atmospheric boundary layer with increased O₃ deposition and concentration of local emissions of both CHCl₃ and CHBr₃. The ratio of ΔCHCl₃/ΔCHBr₃ varied strongly according to the prevailing wind direction; from 0.60+0.15 in south-easterly (100-170° and northerly (340-20°) air to 2.5+0.4 in north-easterly (40-70°) air. Of these land-sectors, the south-easterly air masses are likely to be strongly influenced by macroalgal beds along the coast and the emission ratios probably reflect those from seaweeds in addition to land sources. The north-easterly airmasses however had an immediate fetch inland, which locally is comprised of coastal peatland ecosystems (peat bogs and coastal conifer plantations), previously identified as being strong sources of atmospheric CHCl₃ under these conditions. Although we cannot entirely rule out other local land or coastal sources, our observations also suggest peatland ecosystem emissions of CHBr₃. We use correlations between CHCl₃ and CHBr₃ during the north-easterly land breeze events in conjunction with previous estimates of local wetland CHCl₃ release to tentatively deduce a global wetland CHBr₃ source of 20.4(0.4-948) Gg yr^-1, which is approximately 7% of the total global source

THE EFFECTS OF AUTOMATION EXPERTISE AND SYSTEM CONFIDENCE ON TRUST BEHAVIORS

Trust in automation is more likely to be appropriate when information about the automation's capability is available. The goal of this study was to determine how automation expertise and system confidence affected automation trust behaviors. Forty-one participants completed a target detection task while receiving advice from an imperfect diagnostic aid that varied in expertise (expert vs. novice) and confidence (75% vs. 50% vs. 25%, no aid). Results showed that participants were more willing to comply with the highly confident expert aid than the highly confident novice aid. Furthermore, participants were more apt to generate false alarms as system confidence increased. These results suggest that, similar to interpersonal relationships, humans appraise automation features such as confidence and expertise when deciding to comply with automation. Implications and direction for future research are discussed

Iterative method to compute the Fermat points and Fermat distances of multiquarks

The multiquark confining potential is proportional to the total distance of the fundamental strings linking the quarks and antiquarks. We address the computation of the total string distance an of the Fermat points where the different strings meet. For a meson (quark-antiquark system) the distance is trivially the quark-antiquark distance. For a baryon (three quark system) the problem was solved geometrically from the onset, by Fermat and by Torricelli. The geometrical solution can be determined just with a rule and a compass, but translation of the geometrical solution to an analytical expression is not as trivial. For tetraquarks, pentaquarks, hexaquarks, etc, the geometrical solution is much more complicated. Here we provide an iterative method, converging fast to the correct Fermat points and the total distances, relevant for the multiquark potentials. We also review briefly the geometrical methods leading to the Fermat points and to the total distances.Comment: 13 pages, 6 figures, 1 tabl