3,787 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
Baryon Number Flow in High-Energy Collisions
It is not obvious which partons in the proton carry its baryon number (BN).
We present arguments that BN is associated with a specific topology of gluonic
fields, rather than with the valence quarks. The BN distribution is easily
confused with the difference between the quark and antiquark distributions. We
argue, however, that they have quite different x-dependences. The distribution
of BN asymmetry distribution is nearly constant at small x while q(x)-\bar q(x)
\propto \sqrt{x}. This constancy of BN produces energy independence of the \bar
pp annihilation cross section at high energies. Recent measurement of the
baryon asymmetry at small x at HERA confirms this expectation. The BN asymmetry
at mid-rapidities in heavy ion collisions is substantially enhanced by multiple
interactions, as has been observed in recent experiments at the SPS. The same
gluonic mechanism of BN stopping increases the production rate for cascade
hyperons in a good accord with data. We expect nearly the same as at SPS amount
of BN stopped in higher energy collisions at RHIC and LHC, which is, however,
spread ove larger rapidity intervals.Comment: The estimated baryon stopping at RHIC is corrected in the Summar
A polarised QCD condensate: nu p elastic scattering as a probe of U_A(1) dynamics
U_A(1) dynamics have the potential to induce a polarised condensate inside a
nucleon. The formation of this condensate is related to the realisation of
U_A(1) symmetry breaking by tunneling processes such as instantons. If it is
present, the polarised condensate induces a term in g_1 which has support only
at x=0. Tunneling processes then induce a net transfer of ``spin'' from finite
x to x=0. The polarised condensate may be measured by comparing the
flavour-singlet axial charges which are extracted from polarised deep inelastic
and nu p elastic scattering experiments.Comment: 13 pages LaTeX, Section 3 improved to include discussion of the 3
flavour quark instanton interaction; to appear in Mod. Phys. Lett.
Raman Scattering from Atmospheric Nitrogen in the Stratosphere
The Mark II laser radar system at Kingston, Jamaica, has been used to make observations on the Raman shifted line from atmospheric nitrogen at 828.5 nm. The size of the system makes it possible to detect signals from heights of up to 40 kilometres. The effects of aerosol scattering observed using a single wavelength are almost eliminated, and a profile of nitrogen density may be obtained. Assuming a constant mixing ratio, this may be interpreted as a profile of atmospheric density whose accuracy is comparable to that obtained from routine meteorological soundings. In order to obtain an accurate profile several interfering effects have had to be examined and, where necessary, eliminated. These include: 1) Fluorescence in optical components 2) Leakage of signal at 694.3 nm. 3) Overload effects and non-linearities in the receiving and counting electronics. Most of these effects have been carefully examined and comparisons are being made between the observed atmospheric density profiles and local meteorological radio-sonde measurements. Good agreement has been obtained over the region of overlap (15 - 30 KID), discrepancies being of the same order as the experimental accuracy (1-10%), depending on height and length of period of observation
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
- …