20,161 research outputs found
Advanced thin film thermocouples
The fabrication, materials characterization, and performance of thin film platinum rhodium thermocouples on gas turbine alloys was investigated. The materials chosen for the study were the turbine blade alloy systems MAR M200+Hf with NiCoCrAlY and FeCrAlY coatings, and vane alloy systems MAR M509 with FeCrAlY. Research was focussed on making improvements in the problem areas of coating substrate stability, adhesion, and insulation reliability and durability. Diffusion profiles between the substrate and coating with and without barrier coatings of Al2O3 are reported. The relationships between fabrication parameters of thermal oxidation and sputtering of the insulator and its characterization and performance are described. The best thin film thermocouples were fabricated with the NiCoCrAlY coatings which were thermally oxidized and sputter coated with Al2O3
Uncertainty in Measurements of Distance
Ng and van Dam have argued that quantum theory and general relativity give a
lower bound of L^{1/3} L_P^{2/3} on the uncertainty of any distance, where L is
the distance to be measured and L_P is the Planck length. Their idea is roughly
that to minimize the position uncertainty of a freely falling measuring device
one must increase its mass, but if its mass becomes too large it will collapse
to form a black hole. Here we show that one can go below the Ng-van Dam bound
by attaching the measuring device to a massive elastic rod. Relativistic
limitations on the rod's rigidity, together with the constraint that its length
exceeds its Schwarzschild radius, imply that zero-point fluctuations of the rod
give an uncertainty greater than or equal to L_P.Comment: 5 pages LaTe
Tourist Shopping Activities and Development of Travel Sophistication
An ethnographic research approach was used to investigate shopping and consumption behavior of international tourists. This research informed a model that positions a tourist\u27s market-place activity as an evolving process that parallels and supports their advance in travel sophistication. The model illustrates that shopping and consumption may originate as a leisure-recreational pursuit for tourists but is transformed into a learning activity that facilitates their assimilation of a host culture. This, in turn, plays an important role in the tourist\u27s development of travel self-efficacy, as well as their motivation for return trips
Inducer dynamics full-flow, full-admission hydraulic turbine drive Interim report for tasks 1, 2, and 3
Hydrodynamical and mechanical design layout for two-speed hydraulic turbine inducer, computer simulation of pumping system and test facility performance, and study of demonstration uni
The bloodstream differentiation - division of Trypanosoma brucei studied using mitochondrial markers
In the bloodstream of its mammalian host, the African trypanosome Trypanosoma brucei undergoes a life cycle stage differentiation from a long, slender form to a short, stumpy form. This involves three known major events: exit from a proliferative cell cycle, morphological change and mitochondrial biogenesis. Previously, models have been proposed accounting for these events (Matthews & Gull 1994a). Refinement of, and discrimination between, these models has been hindered by a lack of stage-regulated antigens useful as markers at the single-cell level. We have now evaluated a variety of cytological markers and applied them to investigate the coordination of phenotypic differentiation and cell cycle arrest. Our studies have focused on the differential expression of the mitochondrial enzyme dihydrolipoamide dehydrogenase relative to the differentiation-division of bloodstream trypanosomes. The results implicate a temporal order of events: commitment, division, phenotypic differentiation
Cold atom confinement in an all-optical dark ring trap
We demonstrate confinement of Rb atoms in a dark, toroidal optical
trap. We use a spatial light modulator to convert a single blue-detuned
Gaussian laser beam to a superposition of Laguerre-Gaussian modes that forms a
ring-shaped intensity null bounded harmonically in all directions. We measure a
1/e spin-relaxation lifetime of ~1.5 seconds for a trap detuning of 4.0 nm. For
smaller detunings, a time-dependent relaxation rate is observed. We use these
relaxation rate measurements and imaging diagnostics to optimize trap alignment
in a programmable manner with the modulator. The results are compared with
numerical simulations.Comment: 5 pages, 4 figure
Presynchronizing PGF2α and GnRH injections before timed artificial insemination CO-Synch + CIDR program
Fixed-time artificial insemination is an effective management tool that reduces the
labor associated with more conventional artificial insemination programs requiring
detection of estrus. The 7-day CO-Synch + controlled internal drug release (CIDR)
insert protocol has been shown to effectively initiate estrus and ovulation in cycling
and non-cycling suckled beef cows, producing pregnancy rates at or greater than 50%
in beef cows. The gonadotropin-releasing hormone (GnRH) injection that begins the
CO-Synch + CIDR program initiates ovulation in a large proportion of cows, particularly
anestrous cows. The CIDR, which releases progesterone intravaginally, prevents
short estrous cycles that usually follow the first postpartum ovulation in beef cows. Our
hypothesis was that inducing estrus with a prostaglandin injection followed 3 days later
with a GnRH injection, 7 days before applying the 7-day CO-Synch + CIDR protocol,
might increase the percentage of cycling cows that would exhibit synchronous follicular
waves after the onset of the CO-Synch + CIDR protocol. We also hypothesized that
the additional GnRH injection would increase the percentage of anestrous cows that
would ovulate, thereby increasing pregnancy outcomes
Comparison of Measured and Calculated Specific Resistances of Pd/Pt Interfaces
We compare specific resistances (AR equals area A times resistance R) of
sputtered Pd/Pt interfaces measured in two different ways with
no-free-parameter calculations. One way gives 2AR(Pd/Pt) of 0.29 (0.03)
fohm-m(2) and the other 0.17 (0.13) fohm-m(2). From these we derive a best
estimate of 2AR(Pd/Pt) of 0.28 (0.06) fohm-m(2), which overlaps with
no-free-parameter calculations: 2AR(predicted) of 0.30 (0.04) fohm-m(2) for
flat, perfect interfaces, or 0.33 (0.04) fohm-m(2) for interfaces composed of 2
monolayers of a 50percent-50percent PdPt alloy. These results support three
prior examples of agreement between calculations and measurements for pairs of
metals having the same crystal structure and the same lattice parameter to
within 1 percent. We also estimate the spin-flipping probability at Pd/Pt
interfaces as 0.13 (0.08).Comment: 3 pages, 3 figures, submitted for publication New version has
corrected value of delta(Pd/Pt
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