47,205 research outputs found
Summary of the Very Large Hadron Collider Physics and Detector Subgroup
We summarize the activity of the Very Large Hadron Collider Physics and
Detector subgroup during Snowmass 96.Comment: To appear in the Proceedings of the 1996 DPF/DPB Summer Study on New
Directions for High-Energy Physics, Snowmass 9
Aluminum foil interconnects for solar cell panels
Commercially available sonic welding system and a specially-designed tip bonds aluminum foil interconnects to titanium-silver solar cell contacts
Spirillum swimming: theory and observations of propulsion by the flagellar bundle
The hydrodynamics and energetics of helical swimming by the bacterium Spirillum sp. is analysed using observations from medium speed cine photomicrography and theory. The photographic records show that the swimming organism's flagellar bundles beat in a helical fashion just as other bacterial flagella do. The data are analysed according to the rotational resistive theory of Chwang & Wu (1971) in a simple-to-use parametric form with the viscous coefficients C_s and C_n calculated according to the method of Lighthill (1975). Results of the analysis show that Spirillum dissipated biochemical energy in performing work against fluid resistance to motion at an average rate of about 6 X 10^(−8) dyne cm s^(-1) with some 62–72% of the power dissipation due to the non-contractile body. These relationships yield a relatively low hydromechanical efficiency which is reflected in swimming speeds much smaller than a representative eukaryote. In addition the C_n/C_s ratio for the body is shown to lie in the range 0–86-1-51 and that for the flagellar bundle in the range 1–46-1-63. The implications of the power calculations for the Berg & Anderson (1973) rotating shaft model are discussed and it is shown that a rotational resistive theory analysis predicts a 5-cross bridge M ring for each flagellum of Spirillum
SkyMapper and the Southern Sky Survey - a resource for the southern sky
SkyMapper is amongst the first of a new generation of dedicated, wide-field
survey telescopes. The 1.3m SkyMapper telescope features a 5.7 square degree
field-of-view Cassegrain imager and will see first light in late 2007. The
primary goal of the facility is to conduct the Southern Sky Survey a six
colour, six epoch survey of the southern sky. The survey will provide
photometry for objects between 8th and 23rd magnitude with global photometric
accuracy of 0.03 magnitudes and astrometry to 50 mas. This will represent a
valuable scientific resource for the southern sky and in addition provide a
basis for photometric and astrometric calibration of imaging data.Comment: 6 pages, 4 figures, proceedings of ESO Calibration Workshop 200
The Steady-State Transport of Oxygen through Hemoglobin Solutions
The steady-state transport of oxygen through hemoglobin solutions was studied to identify the mechanism of the diffusion augmentation observed at low oxygen tensions. A novel technique employing a platinum-silver oxygen electrode was developed to measure the effective diffusion coefficient of oxygen in steady-state transport. The measurements were made over a wider range of hemoglobin and oxygen concentrations than previously reported. Values of the Brownian motion diffusion coefficient of oxygen in hemoglobin solution were obtained as well as measurements of facilitated transport at low oxygen tensions. Transport rates up to ten times greater than ordinary diffusion rates were found. Predictions of oxygen flux were made assuming that the oxyhemoglobin transport coefficient was equal to the Brownian motion diffusivity which was measured in a separate set of experiments. The close correlation between prediction and experiment indicates that the diffusion of oxyhemoglobin is the mechanism by which steady-state oxygen transport is facilitated
Forward-Invariance and Wong-Zakai Approximation for Stochastic Moving Boundary Problems
We discuss a class of stochastic second-order PDEs in one space-dimension
with an inner boundary moving according to a possibly non-linear, Stefan-type
condition. We show that proper separation of phases is attained, i.e., the
solution remains negative on one side and positive on the other side of the
moving interface, when started with the appropriate initial conditions. To
extend results from deterministic settings to the stochastic case, we establish
a Wong-Zakai type approximation. After a coordinate transformation the problems
are reformulated and analysed in terms of stochastic evolution equations on
domains of fractional powers of linear operators.Comment: 46 page
Lunar concrete for construction
Feasibility of using concrete for lunar-base construction has been discussed recently without relevant data for the effects of vacuum on concrete. Experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the moon are provided in this paper along with specific conclusions from the existing data base
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