1,178 research outputs found
Universal stowage module for future space exploration, design drawings
For abstract, see N74-20534. For complete abstract, see
Backflushing system rapidly cleans fluid filters
Self contained unit can backflush filter elements in fraction of the time expended by presently used equipment. This innovation may be of interest to manufacturers of hydraulic and pneumatic systems as well as to chemical, food, processing, and filter manufacturing industries
Tundra Relief Features near Point Barrow, Alaska
Topography of this area results from erosion and mass wasting of a permafrost terrain, low temperature processes such as thermal expansion and contraction of frozen ground, surface uplift caused by accumulation of, and subsistence resulting from thaw of ground ice. High- and low-centered polygons, ice-wedge troughs, ice-core mounds and thaw basins are features in this region; genetic relations between these are discussed.Traits de relief de la toundra près de Point Barrow, Alaska. La distribution des traits mineurs du relief de la toundra démontre que la topographie joue un rôle majeur dans leur développement. Dans de grandes zones de relief très faible, l'expression locale dépasse souvent la portée régionale. Abstraction faite du relief initial, les plus grandes déviations de la surface plane dans la région de Barrow sont liées à la croissance ou à la fonte de la glace dans le sol. Ce qui donne des traits comme les polygones à centre soulevé ou en creux, les fentes de coins de glace, les monticules à noyau de glace et des cuvettes de fonte de toutes dimensions. On a pu déterminer la genèse de la plupart de ces traits. Cependant, on a mis en doute la formation des cuvettes par la fonte. La cueillette et l'analyse de spécimens de sol gelé ont permis de déterminer leur teneur relative en glace. Ces valeurs extrapolées ont démontré que même les plus grandes cuvettes peuvent être d'origine thermokarstique
Evolution of the Level lnterfluvial Divides on the Kansan Till Plain in Iowa and Missouri
The purpose of this paper is to discuss and evaluate various alternative hypotheses concerning the evolution of the level interfluvial divides on the Kansan Till plain in southern Iowa and northern Missouri. About four-fifths of the plain is dissected (3), but the undissected remnants have an almost flat surface. In contrast to this the undissected portion of the much younger surfaces of the Mankato and Cary till plains have an undulating topography with numerous closed depressions and isolated low knolls
Modification of an astronaut's mock up tool kit Final report
Design and tests of astronauts tool kit and tools for in-flight space maintenanc
The costs and benefits of a vaccination programme for Haemophilus influenzae type 8 disease
Haemophilus influenzae type b (Hib) infection is a major cause of severe bacterial infection in young children in South Africa and world-wide. These diseases can be prevented by immunisation with conjugate Hib vaccines. In South Africa, unlike some developed countries, Hib vaccines are not part of the routine immunisation schedule. The objective of this study was to measure the expected net benefits from a hypothetical programme of vaccination of the 1992 Cape Town birth cohort (N =46 537). Costs were calculated by summing the estimated direct medical care costs together with the indirect costs of Hib disease. The latter were calculated by valuing human life using alternative, and conservative human capital and willingness-to-pay measures. The difference between Hib disease costs (Le. the benefits which would be gained from a successful vaccination programme) and the costs of the vaccination programme itself (HibTITER, Praxis Biologicals) defined the expected net benefits. In the absence of an immunisation programme, the estimated economic costs of Hib disease in the 1992 Cape Town cohort ranged from R10,7 million to R11 ,8 million. The costs of introducing the vaccine would have amounted to R8,3 million. Had the vaccine been administered to the 1992 birth cohort, benefits would have exceeded costs by between R2,4 million and R3,5 million
Universal stowage module for future space exploration
The design effort to develop, design, and fabricate a prototype Universal Stowage Module with universal restraints that are readily adaptable for most sizes and shapes of items that would be launched into space and returned aboard shuttle payloads is presented
On the transport and thermodynamic properties of quasi-two-dimensional purple bronzes AMoO (A=Na, K)
We report a comparative study of the specific heat, electrical resistivity
and thermal conductivity of the quasi-two-dimensional purple bronzes
NaMoO and KMoO, with special emphasis on
the behavior near their respective charge-density-wave transition temperatures
. The contrasting behavior of both the transport and the thermodynamic
properties near is argued to arise predominantly from the different
levels of intrinsic disorder in the two systems. A significant proportion of
the enhancement of the thermal conductivity above in
NaMoO, and to a lesser extent in KMoO, is
attributed to the emergence of phason excitations.Comment: 8 pages, 6 figures, To appear in Physical Review
Nonsaturating magnetoresistance and nontrivial band topology of type-II Weyl semimetal NbIrTe4
Weyl semimetals, characterized by nodal points in the bulk and Fermi arc
states on the surface, have recently attracted extensive attention due to the
potential application on low energy consumption electronic materials. In this
report, the thermodynamic and transport properties of a theoretically predicted
Weyl semimetal NbIrTe4 is measured in high magnetic fields up to 35 T and low
temperatures down to 0.4 K. Remarkably, NbIrTe4 exhibits a nonsaturating
transverse magnetoresistance which follows a power-law dependence in B.
Low-field Hall measurements reveal that hole-like carriers dominate the
transport for T 80 K, while the significant enhancement of electron
mobilities with lowering T results in a non-negligible contribution from
electron-like carriers which is responsible for the observed non-linear Hall
resistivity at low T. The Shubnikov-de Haas oscillations of the Hall
resistivity under high B give the light effective masses of charge carriers and
the nontrivial Berry phase associated with Weyl fermions. Further
first-principles calculations confirm the existence of 16 Weyl points located
at kz = 0, 0.02 and 0.2 planes in the Brillouin zone.Comment: 5 figures, 1 tabl
Neutron interferometric measurement of the scattering length difference between the triplet and singlet states of n-He
We report a determination of the n-He scattering length difference
(
(statistical) (systematic)) fm between the triplet and singlet
states using a neutron interferometer. This revises our previous result (-5.610 (statistical) (systematic)
fm obtained using the same technique in 2008. This revision is due to a
re-analysis of the 2008 experiment that includes a more robust treatment of the
phase shift caused by magnetic field gradients near the He cell.
Furthermore, we more than doubled our original data set from 2008 by acquiring
six months of additional data in 2013. Both the new data set and a re-analysis
of the older data are in good agreement. Scattering lengths of low Z isotopes
are valued for use in few-body nuclear effective field theories, provide
important tests of modern nuclear potential models and in the case of He
aid in the interpretation of neutron scattering from quantum liquids. The
difference was determined by measuring the relative phase
shift between two incident neutron polarizations caused by the spin-dependent
interaction with a polarized He target. The target He gas was sealed
inside a small, flat windowed glass cell that was placed in one beam path of
the interferometer. The relaxation of He polarization was monitored
continuously with neutron transmission measurements. The neutron polarization
and spin flipper efficiency were determined separately using He analyzers
and two different polarimetry analysis methods. A summary of the measured
scattering lengths for n-He with a comparison to nucleon interaction models
is given
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