Improved high-performance shock tube

Mylar diaphragms in shock tubes are a major improvement over steel diaphragms. Other improvements include: better electrode design; improved flow by opening the throat and removing all constrictions; and improved driver geometry by optimizing volume and shape

A program for computing shock-tube gas dynamic properties

Computer program calculates thermodynamic properties from basic spectroscopic data. Program capacity is a mixture of 100 different species composed of ten different elements. The output is a complete thermodynamic and chemical description of the gas

Shock-tube thermochemistry tables for high- temperature gases, 90% carbon dioxide and 10% nitrogen, volume 2

Shock tube tabulated computer equilibrium thermodynamic properties for carbon dioxide and nitrogen mixtur

The Foggy Disks Surrounding Herbig Ae Stars: a Theoretical Study of the H2O Line Spectra

Water is a key species in many astrophysical environments, but it is particularly important in proto-planetary disks. So far,observations of water in these objects have been scarce, but the situation should soon change thanks to the Herschel satellite. We report here a theoretical study of the water line spectrum of a proto-planetary disk surrounding Ae stars. We show that several lines will be observable with the HIFI instrument onboard the Herschel Space Observatory. We predict that some maser lines could also be observable with ground telescopes and we discuss how the predictions depend not only on the adopted physical and chemical model but also on the set of collisional coefficients used and on the H2 ortho to para ratio through its effect on collisional excitation. This makes the water lines observations a powerful, but dangerous -if misused- diagnostic tool.Comment: Accepted for publication in ApJ Letter

Religious Preference and Spanking Beliefs: Implications for School Corporal Punishment Policies

AMERICAN spanking beliefs were investigated by religious preference. Proportions agreeing with spanking were largest for Protestant (81%), followed by Catholic (69%). The association between Protestant and agreement with spanking (b=.718) was surprisingly strong considering associations with Catholic, Jewish, None, and Other were all inverse. The smaller Jewish proportion agreeing with spanking (51%) and the very strong inverse relationship between Jewish and agreement with spanking (b= -1.072) were unexpected. A separate analysis found large Christian (81%) and small Moslem (51%) proportions agreeing with spanking. Corporal punishment policies reflect American collective conscience on spanking. Deeper understandings of relationships between religious preference and spanking beliefs help stakeholders become aware of cultural undercurrents affecting school environments

Gaussian beam resonator formalism using the yy method

A simple and powerful new paraxial ray formalism is shown to provide an alternate method for designing Gaussian Beam Resonators. The theory utilizes the Delano yybar diagram approach and is an extension of the recent work by Shack and Kessler for laser systems. The method is shown to be complementary to the conventional ABCD method and is founded upon J.A. Arnaud\u27s pioneering ideas for complex rays. The thesis develops an analytic formulation of a ray based complex wavefront curvature and yields a clearly generalized description of spherical wave propagation, for which Gaussian beams are considered a special case. The resultant theory unifies the complex q parameter and the ABCD law, with the yybar complex ray components and also suggests that the ABCD law for the complex q parameter has its origin in the yybar complex ray. New fundamental equations for designing stable multi-element resonators using the yybar coordinates are derived, and it is shown that the yybar diagram provides a novel method for defining automatically stable resonators. Various applications for the yybar design technique are also discussed, including the setting of convenient design constraints, the description of M2 beams, generating phase diagrams, and resonator synthesis and analysis

Microlensing of Circumstellar Disks

We investigate the microlensing effects on a source star surrounded by a circumstellar disk, as a function of wavelength. The microlensing light curve of the system encodes the geometry and surface brightness profile of the disk. In the mid- and far-infrared, the emission of the system is dominated by the thermal emission from the cold dusty disk. For a system located at the Galactic center, we find typical magnifications to be of order 10-20% or higher, depending on the disk surface brightness profile, and the event lasts over one year. At around 20 microns, where the emission for the star and the disk are comparable, the difference in the emission areas results in a chromatic microlensing event. Finally, in the near-infrared and visible, where the emission of the star dominates, the fraction of star light directly reflected by the disk slightly modifies the light curve of the system which is no longer that of a point source. In each case, the corresponding light curve can be used to probe some of the disk properties. A fraction of 0.1% to 1% optical microlensing events are expected to be associated with circumstellar disk systems. We show that the lensing signal of the disk can be detected with sparse follow-up observations of the next generation space telescopes. While direct imaging studies of circumstellar disks are limited to the solar neighborhood, this microlensing technique can probe very distant disk systems living in various environments and has the potential to reveal a larger diversity of circumstellar disks.Comment: 9 pages, 7 figures. Accepted for publication in Ap

Where is the warm H2 ? A search for H2 emission from disks around Herbig Ae/Be stars

Mid-IR emission lines of H2 are useful probes to determine the mass of warm gas present in the surface layers of disks. Numerous observations of Herbig Ae/Be stars (HAeBes) have been performed, but only 2 detections of mid-IR H2 toward HD97048 and AB Aur have been reported. We aim at tracing the warm gas in the disks of 5 HAeBes with gas-rich environments and physical characteristics close to those of AB Aur and HD97048, to discuss whether the detections toward these 2 objects are suggestive of peculiar conditions for the gas. We search for the H2 S(1) emission line at 17.035 \mu\m with VISIR, and complemented by CH molecule observations with UVES. We gather the H2 measurements from the literature to put the new results in context and search for a correlation with some disk properties. None of the 5 VISIR targets shows evidence for H2 emission. From the 3sigma upper limits on the integrated line fluxes we constrain the amount of optically thin warm gas to be less than 1.4 M_Jup in the disk surface layers. There are now 20 HAeBes observed with VISIR and TEXES instruments to search for warm H2, but only two detections (HD97048 and AB Aur) were made so far. We find that the two stars with detected warm H2 show at the same time high 30/13 \mu\m flux ratios and large PAH line fluxes at 8.6 and 11.3 \mu\m compared to the bulk of observed HAeBes and have emission CO lines detected at 4.7 \mu\m. We detect the CH 4300.3A absorption line toward both HD97048 and AB Aur with UVES. The CH to H2 abundance ratios that this would imply if it were to arise from the same component as well as the radial velocity of the CH lines both suggest that CH arises from a surrounding envelope, while the detected H2 would reside in the disk. The two detections of the S(1) line in the disks of HD97048 and AB Aur suggest either peculiar physical conditions or a particular stage of evolution.Comment: accepted for publication in A&A : 10 pages, 6 figure