21,095 research outputs found
Ore deposits in volcanic rocks on earth with lunar extrapolation
Ore deposits in volcanic rocks on earth with lunar extrapolatio
High resolution solar X-ray studies
Two high resolution solar X-ray payloads and their launches on Aerobee rockets with pointing system are described. The payloads included 5 to 25A X-ray spectrometers, multiaperture X-ray cameras, and command box attitude control inflight by means of a television image radioed to ground. Spatial resolution ranged from five arc minutes to ten arc seconds and spectral resolution ranged from 500 to 3000. Several laboratory tasks were completed in order to achieve the desired resolution. These included (1) development of techniques to align grid collimators, (2) studies of the spectrometric properties of crystals, (3) measurements of the absorption coefficients of various materials used in X-ray spectrometers, (4) evaluation of the performance of multiaperture cameras, and (5) development of facilities
Water in massive star-forming regions: HIFI observations of W3 IRS5
We present Herschel observations of the water molecule in the massive star-forming region W3 IRS5. The o-H_(2)^(17)O 1_(10)-1_(01), p-H_(2_^(18)O 1_(11)-0_(00), p-H_(2)O 2_(02)-1_(11), p-H_(2)O 1_(11)-0_(00), o-H_(2)O 2_(21)-2_(12), and o-H_(2)O 2_(12)-1_(01) lines, covering a frequency range from 552 up to 1669 GHz, have been detected at high spectral resolution with HIFI. The water lines in W3 IRS5 show well-defined high-velocity wings that indicate a clear contribution by outflows. Moreover, the systematically blue-shifted absorption in the H_(2)_O lines suggests expansion, presumably driven by the outflow. No infall signatures are detected. The p-H_(2)O 1_(11)-0_(00) and o-H_(2)O 2_(12)-1_(01) lines show absorption from the cold material (T ~ 10 K) in which the high-mass protostellar envelope is embedded. One-dimensional radiative transfer models are used to estimate water abundances and to further study the kinematics of the region. We show that the emission in the rare isotopologues comes directly from the inner parts of the envelope (T ≳ 100 K) where water ices in the dust mantles evaporate and the gas-phase abundance increases. The resulting jump in the water abundance (with a constant inner abundance of 10^(-4)) is needed to reproduce the o-H_(2)^(17)O 1_(10)-1_(01) and p-H_(2)^(18)O 1_(11)-0_(00) spectra in our models. We estimate water abundances of 10^(-8) to 10^(-9) in the outer parts of the envelope (T ≲ 100 K). The possibility of two protostellar objects contributing to the emission is discussed
PRICE VERSUS QUOTA REDUCTIONS: U.S. FLUE-CURED TOBACCO POLICY
Declining domestic cigarette consumption, increased global competition, and loss of import restrictions indicate decreased demand for U.S. flue-cured tobacco. The effects of 10% declines in domestic and export demand are evaluated under a policy of reducing quota to maintain price versus a policy of allowing price to fall to maintain quota. Changes in prices, quantities, revenues, and economic rents are simulated. Losses to nonfarming quota owners are minimized under a policy of price maintenance, while losses in revenues to tobacco-producing areas are minimized by a policy of quota maintenance. Aggregate losses to tobacco growers are greater under a policy of quota maintenance.Flue-cured, Policy, Price reduction, Quota, Tobacco, Agricultural and Food Policy,
Determining the HI content of galaxies via intensity mapping cross-correlations
We propose an innovative method for measuring the neutral hydrogen (HI)
content of an optically-selected spectroscopic sample of galaxies through
cross-correlation with HI intensity mapping measurements. We show that the
HI-galaxy cross-power spectrum contains an additive shot noise term which
scales with the average HI brightness temperature of the optically-selected
galaxies, allowing constraints to be placed on the average HI mass per galaxy.
This approach can estimate the HI content of populations too faint to directly
observe through their 21cm emission over a wide range of redshifts. This
cross-correlation, as a function of optical luminosity or colour, can be used
to derive HI-scaling relations. We demonstrate that this signal will be
detectable by cross-correlating upcoming Australian SKA Pathfinder (ASKAP)
observations with existing optically-selected samples. We also use
semi-analytic simulations to verify that the HI mass can be successfully
recovered by our technique in the range M_HI > 10^8 M_solar, in a manner
independent of the underlying power spectrum shape. We conclude that this
method is a powerful tool to study galaxy evolution, which only requires a
single intensity mapping dataset to infer complementary HI gas information from
existing optical and infra-red observations.Comment: 8 pages, 4 figures, submitted to MNRA
Thin radiating shock layer about a blunt body
Boundary layer flow in thin shock layer about axisymmetric blunt bodies studied by Blasius type series expansion techniqu
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Clinically applicable GABA receptor positive allosteric modulators promote Ăź-cell replication.
A key goal of diabetes research is to develop treatments to safely promote human Ăź-cell replication. It has recently become appreciated that activation of Îł-aminobutyric acid receptors (GABA-Rs) on Ăź-cells can promote their survival and replication. A number of positive allosteric modulators (PAMs) that enhance GABA's actions on neuronal GABAA-Rs are in clinical use. Repurposing these GABAA-R PAMs to help treat diabetes is theoretically appealing because of their safety and potential to enhance the ability of GABA, secreted from Ăź-cells, or exogenously administered, to promote Ăź-cell replication and survival. Here, we show that clinically applicable GABAA-R PAMs can increase significantly INS-1 Ăź-cell replication, which is enhanced by exogenous GABA application. Furthermore, a GABAA-R PAM promoted human islet cell replication in vitro. This effect was abrogated by a GABAA-R antagonist. The combination of a PAM and low levels of exogenous GABA further increased human islet cell replication. These findings suggest that PAMs may potentiate the actions of GABA secreted by islet Ăź-cells on GABAA-Rs and provide a new class of drugs for diabetes treatment. Finally, our findings may explain a past clinical observation of a GABAA-R PAM reducing HbA1c levels in diabetic patients
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