Radio Continuum Study of Supernova Remnants in the Large Magellanic Cloud - SNR J0519-6926

We present the results of new high resolution ATCA observations of SNR J0519-6926. We found that this SNR exhibits a typical "horseshoe" appearance with alpha = -0.55 +- 0.08 and D=28+-1 pc. No polarization (or magnetic fields) are detected to a level of 1%. This is probably due to a relatively poor sampling of the uv plane caused be observing in "snap-shot" mode.Comment: 6 pages 4 figures, to be published in Serbian Astronomical Journa

A lower bound to the spectral threshold in curved tubes

We consider the Laplacian in curved tubes of arbitrary cross-section rotating together with the Frenet frame along curves in Euclidean spaces of arbitrary dimension, subject to Dirichlet boundary conditions on the cylindrical surface and Neumann conditions at the ends of the tube. We prove that the spectral threshold of the Laplacian is estimated from below by the lowest eigenvalue of the Dirichlet Laplacian in a torus determined by the geometry of the tube.Comment: LaTeX, 13 pages; to appear in R. Soc. Lond. Proc. Ser. A Math. Phys. Eng. Sc

The Strongest 100 Point Radio Sources in the LMC at 1.4 GHz

We present the 100 strongest 1.4 GHz point sources from a new mosaic image in the direction of the Large Magellanic Cloud (LMC). The observations making up the mosaic were made over a ten year period and were combined with Parkes single dish data at 1.4 GHz to complete the image for short spacing. An initial list of co-identifications within 10" at 0.843, 4.8 and 8.6 GHz consisted of 2682 sources. Elimination of extended objects and artifact noise allowed the creation of a refined list containing 1988 point sources. Most of these are presumed to be background objects seen through the LMC; a small portion may represent compact H II regions, young SNRs and radio planetary nebulae. For the 1988 point sources we find a preliminary average spectral index of -0.53 and present a 1.4 GHz image showing source location in the direction of the LMC.Comment: 8 pages, 2 figure

The prevalence of medical reasons for non-participation in the Scottish breast and bowel cancer screening programmes

Objective: Increasing uptake of cancer screening is a priority for health systems internationally, however, some patients may not attend because they are undergoing active treatment for the cancer of interest or have other medical reasons that mean participation would be inappropriate. This study aims to quantify the proportion of non-participants who have a medical reason for not attending cancer screening.<p></p> Methods: Medical reasons for not participating in breast and bowel screening were defined a priori on the basis of a literature review and expert opinion. The notes of 700 patients at two GP practices in Scotland were reviewed, to ascertain the prevalence of medical reasons amongst non-participants. Simple proportions and confidence intervals were calculated.<p></p> Results: 17.4% of breast and 2.3% of bowel screening non-participants had a medical reason to not participate. The two most common reasons were previous breast cancer follow up (8.86%) and recent mammogram (6.57%).<p></p> Conclusion: These patients may not benefit from screening while also being distressed by receiving an invitation. This issue also makes accurate monitoring and target-setting for improving uptake difficult. Further work is needed to estimate robustly the extent to which medical reasons account for screening non-participation in a larger population.<p></p&gt

New Consequences of Induced Transparency in a Double-Lambda scheme: Destructive Interference In Four-wave Mixing

We investigate a four-state system interacting with long and short laser pulses in a weak probe beam approximation. We show that when all lasers are tuned to the exact unperturbed resonances, part of the four-wave mixing (FWM) field is strongly absorbed. The part which is not absorbed has the exact intensity required to destructively interfere with the excitation pathway involved in producing the FWM state. We show that with this three-photon destructive interference, the conversion efficiency can still be as high as 25%. Contrary to common belief,our calculation shows that this process, where an ideal one-photon electromagnetically induced transparency is established, is not most suitable for high efficiency conversion. With appropriate phase-matching and propagation distance, and when the three-photon destructive interference does not occur, we show that the photon flux conversion efficiency is independent of probe intensity and can be close to 100%. In addition, we show clearly that the conversion efficiency is not determined by the maximum atomic coherence between two lower excited states, as commonly believed. It is the combination of phase-matching and constructive interference involving the two terms arising in producing the mixing wave that is the key element for the optimized FWM generation. Indeed, in this scheme no appreciable excited state is produced, so that the atomic coherence between states |0> and |2> is always very small.Comment: Submitted to Phys. Rev. A, 7 pages, 4 figure

Rate constant for the reaction of hydroxyl radical with formaldehyde over the temperature range 228-362 K

Absolute rate constants for the reaction OH ? H2CO measured over the temperature range 228-362 K using the flash photolysis-resonance fluorescence technique are given. The results are independent of variations in H2CO concentration, total pressure Ar concentration, and flash intensity (i.e., initial OH concentration). The rate constant is found to be invariant with temperature in this range, the best representation being k sub 1 = (1.05 ? or - 0.11) x 10 to the 11th power cu cm molecule(-1) s(-1) where the error is two standard deviations. This result is compared with previous absolute and relative determinations of k sub 1. The reaction is also discussed from a theoretical point of view

Study of state-of-the-art static inverter design Final report, 6 Jan. - 6 Jun. 1966

Multiple purpose inverter design based on phase demodulated inverter circuit selected from state-of-the-art assessment of ten inverter circuit

Two-Phase Flow of Two HFC Refrigerant Mixtures Through Short Tube Orifices, Draft Final Report

The need for new refrigerants was established when scientists first realized the ozone depleting effects of CFC and HCFC refrigerants. The chlorine atom in these refrigerants is capable of reaching the upper atmosphere where one chlorine atom can destroy more than 100,000 ozone atoms(Lang1ey 1994). Laws have been enacted to halt the destruction of the ozone layer and force industry to find replacements for the ozone depleting refrigerants. Section 608 of the Clean Air Act (1990) prohibited the venting of ozone depleting refrigerants as of July 1, 1992. In addition the Clean Air Act (1990) also requires the EPA to develop regulations limiting the emissions of ozone depleting refrigerants. Efforts are currently underway to find CFC replacements before the complete phaseout of CFC manufacturing in January of 1996. Much of the effort to replace CFC and HCFC refrigerants has centered on development of refrigerant mixtures that could replace R-22. Before systems can be designed with a new refrigerant (or mixture), thermodynamic and thermophysical properties must first be characterized. An important component in air conditioners is the expansion device. Because of their low cost, several manufacturers have chosen to use short tube orifices for the expansion device in their systems. Designing a system with an orifice requires knowledge of the flow characteristics of short tube orifices. Recent work on orifices has focused on R-12 and R-22 (Kim and O'Neal, 1993a; Aaron and Domanski, 1990; Krakow, 1988; and Mei, 1982). In addition, there are unpublished data on R-134a @m and ONeal, 1993b) and the effect of lubricants on flow characteristics (Kim, 1993; Kim and O'Neal, 1994b).The present study presents data for flow of two refrigerant mixtures through short tube orifices. The two mixtures were R3211251134a (23%/25%/52% on a mass percentage basis) and R321125 (50%/50%). The following presents results for the flow of these two refrigerants through short tube orifices of various diameters and lengths of 0.5 in (12.7 mm), 0.75 in (19.05 mm), and 1.00 in (25.4 mm) in a pure form and mixed with various mass percentages of oil