51,705 research outputs found
Global mapping of iron and titanium oxides in the lunar megaregolith and subsurface
[Abstract]:
This paper reports mapping results obtained by remote sensing analysis of Iron and Titanium oxides in the megaregolith under the lunar Highlands regolith and in the subsurface under the Mare and South Pole Aitken basin regolith. FeO and TiO2 images were mosaicked from data extracted from the 1994 Clementine lunar orbiter mission from 600 N to 600 S, using the Lucey et al. technique (2000). These images then used to study the ejecta blanket for each of 2059 craters analysed using ISIS software (US Geological Survey). Average weight percentage values for each crater ejecta blanket were interpolated to derive underlying global Province Maps for FeO and TiO2. The Moon was divided into five (5) provinces as a balance of the needs of analysis requirements and simplicity. Division of global TiO2 weight percentages in the megaregolith /subsurface five provinces was matching the observed distribution of that at the surface. In contrast, division of lunar FeO into 5 Provinces reveals unexpectedly elevated iron concentrations (3.8 to 6.4%) in some areas of the Highland megaregolith. This Province of elevated iron oxide is termed “Highland II”
Probing expert anticipation with the temporal occlusion paradigm: Experimental investigations of some methodological issues
Copyright @ 2005 Human KineticsTwo experiments were conducted to examine whether the conclusions drawn regarding the timing of anticipatory information pick-up from temporal occlusion studies are influenced by whether (a) the viewing period is of variable or fixed duration and (b) the task is a laboratory-based one with simple responses or a natural one requiring a coupled, interceptive movement response. Skilled and novice tennis players either made pencil-and-paper predictions of service direction (Experiment 1) or attempted to hit return strokes (Experiment 2) to tennis serves while their vision was temporally occluded in either a traditional progressive mode (where more information was revealed in each subsequent occlusion condition) or a moving window mode (where the visual display was only available for a fixed duration with this window shifted to different phases of the service action). Conclusions regarding the timing of information pick-up were generally consistent across display mode and across task setting lending support to the veracity and generalisability of findings regarding perceptual expertise in existing laboratory-based progressive temporal occlusion studies.This study is funded by the Australian Institute of Sport Tennis program
Elastic interaction between colloidal particles in confined nematic liquid crystals
The theory of elastic interaction of micron size axially symmetric colloidal
particles immersed into confined nematic liquid crystal has been proposed.
General formulas are obtained for the self energy of one colloidal particle and
interaction energy between two particles in arbitrary confined NLC with strong
anchoring condition on the bounding surface. Particular cases of dipole-dipole
interaction in the homeotropic and planar nematic cell with thickness are
considered and found to be exponentially screened on far distances with decay
length . It is predicted that bounding surfaces in
the planar cell crucially change the attraction and repulsion zones of usual
dipole-dipole interaction. As well it is predicted that \textit{the decay
length} in quadrupolar interaction is \textit{two times smaller} than for the
dipolar case.Comment: 4 pages,2 figure
The stability of solitons in biomembranes and nerves
We examine the stability of a class of solitons, obtained from a
generalization of the Boussinesq equation, which have been proposed to be
relevant for pulse propagation in biomembranes and nerves. These solitons are
found to be stable with respect to small amplitude fluctuations. They emerge
naturally from non-solitonic initial excitations and are robust in the presence
of dissipation.Comment: 7 pages, 5 figure
On Pauli Pairs
The state of a system in classical mechanics can be uniquely reconstructed if
we know the positions and the momenta of all its parts. In 1958 Pauli has
conjectured that the same holds for quantum mechanical systems. The conjecture
turned out to be wrong. In this paper we provide a new set of examples of Pauli
pairs, being the pairs of quantum states indistinguishable by measuring the
spatial location and momentum. In particular, we construct a new set of
spatially localized Pauli pairs.Comment: submitted to JM
Vehicle Design for Mars Landing and Return to Mars Orbit
This paper briefly describes three modes for accomplishing the Mars landing mission and compares them on a gross basis to indicate their probable order of merit and to identify design requirements placed on the Mars-excursion module (MEM) by the choice of mode. The paper shows that a flyby-rendezvous mode requiring low weight in earth orbit requires the MEM to enter the Mars atmosphere at velocities ranging from 20,000 to 30,000 ft/sec. The MEM for the flyby-rendezvous mode is not covered in this paper but merits further study. The MEM for the other modes of mission accomplishment begins its active operational sequence in Mars orbit and need not be greatly influenced by the method of delivery to Mars orbit. Parametric studies of the entry problem for two vehicles typifying a ballistic-type and a lifting-body-type were conducted to identify the problems associated with design of a MEM to accommodate the extremes of Mars atmospheric density presently predicted. This brief study indicates that: (a) the presently predicted density extremes of the Mars atmosphere present no serious design problems for a MEM which can operate across the entire band of predicted densities; (b) details of operational requirements and mission objectives will control the choice of configuration rather than entry requirements; and (c) the ballistic-type MEM is lighter and simpler but has less operational flexibility than a high L/D MEM
Controlled manipulation of light by cooperative response of atoms in an optical lattice
We show that a cooperative atom response in an optical lattice to resonant
incident light can be employed for precise control and manipulation of light on
a subwavelength scale. Specific collective excitation modes of the system that
result from strong light-mediated dipole-dipole interactions can be addressed
by tailoring the spatial phase-profile of the incident light. We demonstrate
how the collective response can be used to produce optical excitations at
well-isolated sites on the lattice.Comment: 8 pages, 1 figur
The changes in chemical composition during development of the bovine nuchal ligament
Whole bovine nuchal ligaments, or portions thereof (in the case of commercially valuable animals), were obtained from 45 animals (28 fetal and 17 postnatal) ranging in age from 110 days of gestation to 10 yr. Insoluble elastin was quantitatively prepared from the fresh ligaments by extraction with hot alkali and by a combination of multiple extractions with alkaline buffer and then repeated autoclaving. When adult samples were examined, the yields of insoluble residue by these two methods were very similar, but with young fetal samples the second method gave significantly higher values, because of incomplete purification of the elastin residue. The changes in the concentration of collagen, alkali-insoluble elastin, and DNA have been examined. DNA concentration, and, thus, cell population density, fell progressively during the fetal period of development, to reach a steady value soon after birth. Collagen appeared in appreciable quantities before elastin, but its concentration was rapidly halved at about the time of birth. Insoluble elastin concentration was low until the end of the 7th fetal month, at which time it began to rise rapidly. The rate of increase in elastin concentration remained high throughout the next 10–12 wk, by which time the adult value had been reached. Quantitative studies, on the basis of the whole ligament, showed that the total cell content rises to a maximum at birth, but falls soon after to a level about half that at birth. Total collagen production and elastin deposition continue at a steady, maximal rate over the interval from 235 days of gestation to the end of the 1st postnatal month. It is concluded that the immediate postnatal period would be the most favorable phase in which to attempt the isolation of the soluble precursor elastin
- …