4,500 research outputs found
Left seat command or leadership flight, leadership training and research at North Central Airlines
The need for flight leadership training for flight deck crewmembers is addressed. A management grid is also described which provides a quantitative management language against which any number of management behaviors can be measured
Strange form factors of the proton: a new analysis of the neutrino (antineutrino) data of the BNL-734 experiment
We consider ratios of elastic neutrino(antineutrino)-proton cross sections
measured by the Brookhaven BNL-734 experiment and use them to obtain the
neutral current (NC) over charged current (CC) neutrino-antineutrino asymmetry.
We discuss the sensitivity of these ratios and of the asymmetry to the
electric, magnetic and axial strange form factors of the nucleon and to the
axial cutoff mass M_A. We show that the effects of the nuclear structure and
interactions on the asymmetry and, in general, on ratios of cross sections are
negligible. We find some restrictions on the possible values of the parameters
characterizing the strange form factors. We show that a precise measurement of
the neutrino-antineutrino asymmetry would allow the extraction of the axial and
vector magnetic strange form factors in a model independent way. The
neutrino-antineutrino asymmetry turns out to be almost independent on the
electric strange form factor and on the axial cutoff mass.Comment: 12 page
Research in interactive scene analysis
An interactive scene interpretation system (ISIS) was developed as a tool for constructing and experimenting with man-machine and automatic scene analysis methods tailored for particular image domains. A recently developed region analysis subsystem based on the paradigm of Brice and Fennema is described. Using this subsystem a series of experiments was conducted to determine good criteria for initially partitioning a scene into atomic regions and for merging these regions into a final partition of the scene along object boundaries. Semantic (problem-dependent) knowledge is essential for complete, correct partitions of complex real-world scenes. An interactive approach to semantic scene segmentation was developed and demonstrated on both landscape and indoor scenes. This approach provides a reasonable methodology for segmenting scenes that cannot be processed completely automatically, and is a promising basis for a future automatic system. A program is described that can automatically generate strategies for finding specific objects in a scene based on manually designated pictorial examples
Effects of sugars on lipid bilayers during dehydration - SAXS/WAXS measurements and quantitative model
We present an X-ray scattering study of the effects of dehydration on the bilayer and chain-chain repeat spacings of dipalmitoylphosphatidylcholine bilayers in the presence of sugars. The presence of sugars has no effect on the average spacing between the phospholipid chains in either the fluid or gel phase. Using this finding, we establish that for low sugar concentrations only a small amount of sugar exclusion occurs. Under these conditions, the effects of sugars on the membrane transition temperatures can be explained quantitatively by the reduction in hydration repulsion between bilayers due to the presence of the sugars. Specific bonding of sugars to lipid headgroups is not required to explain this effect
Kinetics of the lamellar gel-fluid transition in phosphatidylcholine membranes in the presence of sugars
Phase diagrams are presented for dipalmitoylphosphatidylcholine (DPPC) in the presence of sugars (sucrose) over a wide range of relative humidities (RHs). The phase information presented here, determined by small angle X-ray scattering (SAXS), is shown to be consistent with previous results achieved by differential scanning calorimetry (DSC). Both techniques show a significant effect of sucrose concentration on the phase behaviour of this phospholipid bilayer. An experimental investigation into the effect of sugars on the kinetic behaviour of the gel to fluid transition is also presented showing that increasing the sugar content appears to slightly increase the rate at which the transition occurs
The inverse hexagonal - inverse ribbon - lamellar gel phase transition sequence in low hydration DOPC:DOPE phospholipid mixtures
The inverse hexagonal to inverse ribbon phase transition in a mixed phosphatidylcholine-phosphatidylethanolamine system at low hydration is studied using small and wide angle X-ray scattering. It is found that the structural parameters of the inverse hexagonal phase are independent of temperature. By contrast the length of each ribbon of the inverse ribbon phase increases continuously with decreasing temperature over a range of 50° C. At low temperatures the inverse ribbon phase is observed to have a transition to a gel lamellar phase, with no intermediate fluid lamellar phase. This phase transition is confirmed by differential scanning calorimetry
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