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The PULSE@Parkes project has been designed to monitor the rotation of radio pulsars over time spans of days to years. The observations are obtained using the Parkes 64-m and 12-m radio telescopes by Australian and international high school students. These students learn the basis of radio astronomy and undertake small projects with their observations. The data are fully calibrated and obtained with the state-of-the-art pulsar hardware available at Parkes. The final data sets are archived and are currently being used to carry out studies of 1) pulsar glitches, 2) timing noise, 3) pulse profile stability over long time scales and 4) the extreme nulling phenomenon. The data are also included in other projects such as gamma-ray observatory support and for the Parkes Pulsar Timing Array project. In this paper we describe the current status of the project and present the first scientific results from the Parkes 12-m radio telescope. We emphasise that this project offers a straightforward means to enthuse high school students and the general public about radio astronomy while obtaining scientifically valuable data sets.
The artistlike pictures of vortex flows presented here have been produced by the flow itself. The method of this “natural” flow visualization can be described briefly as follows: The working fluid is water mixed with some paste in order to increase the viscosity. Vortex flows are produced by pulling a stick or similar devices through the fluid or by injecting fluid through a nozzle into the working tank.
The flow visualization is performed in the following way: the surface of the fluid at rest is sparkled with oil paint of different colors diluted with some evaporating chemical. After the vortex structures have formed due to wakes or jets, a sheet of white paper is placed on the surface of the working fluid, where the oil color is attached to the paper immediately. The final results are artistlike paintings of vortex flows which exhibit a rich variety of flow structures.
Mixing in regular and chaotic flows
These photographs show the time evolution of two passive tracers in a low Reynolds number two-dimensional timeperiodic flow. The initial condition corresponds to two blobs of dye, green and orange, located below the free surface of a cavity filled with glycerine. The flow is induced by moving the top and bottom walls of the cavity while the other two walls are fixed. In this experiment the top wall moves from left to right and the bottom wall moves from right to left; both velocities are of the form Usin2(2πt/T), with the same U and the same period T, but with a phase shift of 90°.
Direct-write electron beam lithography is a patterning technique that has rapidly evolved over the last 40 years. For many years it has been possible to use electrons to pattern lines with widths as narrow as 10 rum. Recent advances in resist materials, electron sources, and system integration have further enhanced the capabilities. High-sensitivity resists provide substantial increases in the throughput without sacrificing resolution. Thermal field-emission sources improve the stability and reduce the minimum attainable spot size. Modem lithography systems integrate the electron beam column with advanced control electronics, making a system capable of nanometer-scale placement accuracy. In addition to these improvements, the technology is more accessible now than ever before, thanks to the proliferation of lithography systems consisting of modified scanning electron microscopes.
To determine the susceptibilities of vancomycin-resistant and -sensitive enterococci (VRE and VSE) to various concentrations of commonly used, commercial, hospital-grade disinfectants.
A microbial suspension test using inocula of 108 cells per mL in a disinfectant test dilution was used to determine inactivation kinetics of the test strains. In each test, 1-mL aliquots were removed from the cell-disinfectant mixtures at 15 and 30 seconds and then at 1-minute intervals for 5 minutes and neutralized. Appropriate serial dilutions were plated on agar medium for enumeration of survivors.
VRE and VSE challenge inocula (in the absence of any additional protein or serum challenge) were below the limit of detection (5 colony-forming units/mL) after 15 seconds' exposure to the manufacturers' suggested use-dilutions of quaternary ammonium, phenolic, or iodophor germicidal detergents. In subsequent tests, when the disinfectants were diluted far beyond the recommended use-dilutions (extended dilution), no differences were demonstrated between the susceptibilities of VRE and VSE.
VRE and VSE are sensitive to a spectrum of commonly used environmental disinfectants and have parallel inactivation rates when challenged with extended dilutions of these products. Our findings did not demonstrate a relationship between antibiotic and germicide resistance. Routine disinfection and housekeeping protocols presently used in hospitals need not be altered due to concerns about the potential for environmentally mediated transmission of antibiotic-resistant microorganisms.
In this study, we report the synthesis and characterization of a new, systematically designed class of second-order NLO polymers in which the appended chromophoric substituent is modified (hydroxylated) to allow direct chromophore involvement in hydrogen-bonding and crosslinking. Thus, the glassy polymer poly(p-hydroxystyrene) has been functionalized to varying levels with the N-(3-hydroxy-4-nitrophenyl)-(S)-prolinoxy (HNPP) high-β chromophore. The time-dependent second harmonic generation characteristics of thin films of this material have been studied at λ = 1.064 μm as a function of chromophore functionalization level, hydrogen-bonding capacity, and thermal crosslinking. These materials are found to possess high d33 values (up to 34 × 10−9 esu) and long characteristic SHG decay times (longer than a year). Analysis of the decay of the second harmonic signal shows that increasing hydrogen-bonding density substantially increases relaxation times; it is further shown that introduction of crosslinks is yet more effective in imparting SHG temporal stability to these polymeric nonlinear optical materials.
Laboratory investigations were initiated with a povidone-iodine antiseptic solution that was intrinsically contaminated with Pseudomonas cepacia. These investigations were helpful in understanding the microbicidal and chemical properties of iodophor solutions and the mechanism by which P cepacia can survive in iodine-containing antiseptics.
Included in these studies were: prolonged survival of P cepacia; available and free iodine determinations; microbial challenge studies; and scanning electron microscopic examination of contaminated antiseptic.
P cepacia survived in this iodophor antiseptic up to 68 weeks from the date of manufacture. A uniform concentration of 1% available iodine was found in all lots of povidone-iodine tested as specified on the product label, but free iodine (I,) values varied greatly. Low free iodine levels of 0.23 to 0.46 ppm were associated with the contaminated lot of povidone-iodine. Solutions of povidone-iodine with varying levels of free iodine were rapidly microbicidal when challenged with cells of P cepacia derived from culture broth and washed or adapted to growth in water. P cepacia cells taken directly from contaminated povidone-iodine survived for significantly longer periods of time. Large numbers of P cepacia were found embedded in extracellular material and among strands of glycocalyx between cells as shown by scanning electron microscopy.
The physical thickness of cellular and extracellular material that forms on surfaces could protect embedded organisms from the microbicidal action of disinfectants and antiseptics and subsequently allow for extended microbial survival times. Manufacturers should be aware that distribution piping surfaces colonized with bacteria may be a source of product contamination and resistant organisms.
Urinary output of homovanillic acid and 4-hydroxy-3-methoxymandelic acid was decreased both in patients with panic attacks and in normal controls during lactate infusion, whereas that of tribulin (an endogenous monoamine oxidase inhibitor and benzodiazepine receptor binding inhibitor) was increased. There was no change in urinary excretion of any of these compounds during saline infusion. These findings provide further evidence of a link between tribulin output and stress and anxiety in man and point to its possible in vivo action as a monoamine oxidase inhibitor.
Recent investigations into the mineralogical constitution of fireclays have revealed the presence of a micaceous mineral in all samples examined. Naturally-occurring clays may contain up to 30 % of this type of mineral, and exceptional concentrations have been found in the Yorkshire area. Tests on the purified mineral from this source have proved it to be a hydrous mica of an unusually large grain,size.
In the first paper read before this Society “ On some New Bases of the Leucoline Series,” and published in the Society's “ Transactions,” it was stated that amongst other methods proposed for separating the members of the series and identifying the higher bases, was the process of converting the mixed bases into methyl-iodide compounds by digesting them with the iodide at a high temperature, and separating by fractional crystallisation the bodies so produced. It was found, however, that repeated crystallisation of these bodies could not be effected without great risk of their decomposition. This process was, therefore, abandoned in favour of fractional distillation.
In a former paper read before the Society, and published in the Society's “ Transactions,” on ” Some New Bases of the CnH2n—11N series,” obtained from the “ vitriol-tar,” from the distillation of shale, evidence was given of the isolation of three bases of this series, in addition to the Leucoline, Iridoline, and Cryptidine of G. Williams.