Fluid mixing technique increases the gain and output power of carbon dioxide laser systems

High speed flowing gas system provides uniform mixing in short times compared to flow transit times and carbon dioxide vibrational relaxation times. This system minimizes the effects of surrounding surfaces and provides a uniformly high gain that is independent of dimensions transverse to the flow direction

Recombination rates and non-equilibrium electrical conductivity in a seeded plasma

Experimentally determined values of electrical conductivity and electron temperature have been measured in a non-equilibrium seeded plasma. These results are in good agreement over a wide range of parameters with values calculated from a two-temperature model of the plasma. There is no doubt that the two-temperature model is valid over a wide range of gas temperatures, seed concentrations, and current densities for the argon-potassium and helium-potassium plasmas. However, the model does not give an accurate description of the plasma when the current density is below about 0.4 amp/cm^2; in this range the omission of the influence of atom-atom excitation and the influence of non-equilibrium excited state populations may explain the discrepancy between experiment and theory. In addition, the electron-elecron-ion collisional recombination rate for potassium has been measured in the argon-potassium system. The range of electron temperatures investigated was between 1900° K to 3000° K with electron densities between 3X10^(13) and 4x10^(14)/cm^3. The measured values show a scatter of 60 per cent about theoretical values calculated from present recombination-rate theory employing the Gryzinski classical collision cross sections

Experiments Concerning Nonequilibrium Conductivity in a Seeded Plasma

Measurements of conductivity have been made in a plasma composed of argon seeded with potassium vapor. The gas temperature was 2000°K; the pressure, 1 atm; and the potassium concentration was between 0.22 and 0.80 mole-percent. Conductivity values, calculated from a two-temperature model in which the energy dependence of the cross sections and radiation losses from the plasma are taken into account, agree well with experimental values. Measured values of the plasma temperature appear to be about 10% less than predicted values. Relaxation times for the conductivity in response to a step function change in the electric field were proportional to (n_e0l/σ_0E^2) and were a few tens of microseconds for a field strength in the range 3 to 10 v/cm. The ionization rate appeared to be limited primarily by the heating rate for the plasma, and the short relaxation times suggest that ionization occurs by a multistep process. Analysis of conductivity and light intensity data obtained during the transient period indicates that the electron temperature approaches its final value during the first few microseconds

Molecular energy transfer by fluid mixing Progress report, 1 Jan. 1968 - 1 Jan. 1971

CW chemical laser development, N2-C02 electrically excited fluid mixing laser techniques, and gas dynamic mixing behind shock wave

Screening methods for age-related hearing loss in older patients with cancer: A review of the literature

© 2018 by the authors. As people grow older, they may experience loss in hearing sensitivity. Age-related hearing loss may negatively affect the patient's quality of life as it may lead to social isolation. In older patients with cancer, hearing loss can seriously interfere with the patient's ability to deal properly with all aspects of their disease, and may have a cumulative effect on their already decreased quality of life. Therefore, the proper screening of those conditions is essential in order to optimise the patient's comfort during and after treatment. This review article aims at providing a concise image of the nature of age-related hearing loss, and provides an overview of the screening methods that could be used in older patients with cancer

Redshift Distribution of Extragalactic 24 micron Sources

We present the redshift distribution of a complete, unbiased sample of 24 micron sources down to fnu(24 micron) = 300 uJy (5-sigma). The sample consists of 591 sources detected in the Bootes field of the NOAO Deep Wide-Field Survey. We have obtained optical spectroscopic redshifts for 421 sources (71%). These have a redshift distribution peaking at z~0.3, with a possible additional peak at z~0.9, and objects detected out to z=4.5. The spectra of the remaining 170 (29%) exhibit no strong emission lines from which to determine a redshift. We develop an algorithm to estimate the redshift distribution of these sources, based on the assumption that they have emission lines but that these lines are not observable due to the limited wavelength coverage of our spectroscopic observations. The redshift distribution derived from all 591 sources exhibits an additional peak of extremely luminous (L(8-1000 micron) > 3 x 10^{12} Lsun) objects at z~2, consisting primarily of sources without observable emission lines. We use optical line diagnostics and IRAC colors to estimate that 55% of the sources within this peak are AGN-dominated. We compare our results to published models of the evolution of infrared luminous galaxies. The models which best reproduce our observations predict a large population of star-formation dominated ULIRGs at z > 1.5 rather than the AGN-dominated sources we observe.Comment: 21 pages, 11 figures; accepted for publication in Ap

A MMT/Hectospec Redshift Survey of 24 Micron Sources in the Spitzer First Look Survey

We present a spectroscopic survey using the MMT/Hectospec fiber spectrograph of 24 micron sources selected with the Spitzer Space Telescope in the Spitzer First Look Survey. We report 1296 new redshifts for 24 micron sources, including 599 with f(24micron) > 1 mJy. Combined with 291 additional redshifts for sources from the Sloan Digital Sky Survey (SDSS), our observing program was highly efficient and is ~90% complete for i' 1 mJy, and is 35% complete for i' < 20.5 mag and 0.3 mJy < f(24micron) < 1 mJy. Our Hectospec survey includes 1078 and 168 objects spectroscopically classified as galaxies and QSOs, respectively. Combining the Hectospec and SDSS samples, we find 24 micron-selected galaxies to z < 0.98 and QSOs to z < 3.6, with mean redshifts of = 0.27 and =1.1. As part of this publication, we include the redshift catalogs and the reduced spectra; these are also available online (http://mips.as.arizona.edu/~papovich/fls) and through the NASA/IPAC Infrared Science Archive (http://irsa.ipac.caltech.edu).Comment: Accepted for publication in the Astronomical Journal, AASTEX format, 23 pages, 7 figures (some in color). This replacement is the accepted version, and includes minor changes from previous version. Data tables and spectra available at http://mips.as.arizona.edu/~papovich/fls or at http://irsa.ipac.caltech.ed

The Mid-IR and X-ray Selected QSO Luminosity Function

We present the J-band luminosity function of 1838 mid-infrared and X-ray selected AGNs in the redshift range 0<z<5.85. These luminosity functions are constructed by combining the deep multi-wavelength broad-band observations from the UV to the mid-IR of the NDWFS Bootes field with the X-ray observations of the XBootes survey and the spectroscopic observations of the same field by AGES. Our sample is primarily composed of IRAC-selected AGNs, targeted using modifications of the Stern et al.(2005) criteria, complemented by MIPS 24 microns and X-ray selected AGNs to alleviate the biases of IRAC mid-IR selection against z~4.5 quasars and AGNs faint with respect to their hosts. This sample provides an accurate link between low and high redshift AGN luminosity functions and does not suffer from the usual incompleteness of optical samples at z~3. We find that the space density of the brightest quasars strongly decreases from z=3 to z=0, while the space density of faint quasars is at least flat, and possibly increasing, over the same redshift range. At z>3 we observe a decrease in the space density of quasars of all brightnesses. We model the luminosity function by a double power-law and find that its evolution cannot be described by either pure luminosity or pure density evolution, but must be a combination of both. Our best-fit model has bright and faint power-law indices consistent with the low redshift measurements based on the 2QZ and 2SLAQ surveys and it generally agrees with the number of bright quasars predicted by other LFs at all redshifts. If we construct the QSO luminosity function using only the IRAC-selected AGNs, we find that the biases inherent to this selection method significantly modify the behavior of phi*(z) only for z<1 and have no significant impact upon the characteristic magnitude M*_J(z).Comment: Corrected minor typo in equations (4) and (6). Accepted for publication in The Astrophysical Journal. 56 pages + 6 tables + 16 figure

Another Faint UV Object Associated with a Globular Cluster X-Ray Source: The Case of M92

The core of the metal poor Galactic Globular Cluster M92 (NGC 6341) has been observed with WFPC2 on the Hubble Space Telescope through visual, blue and mid-UV filters in a program devoted to study the evolved stellar population in a selected sample of Galactic Globular Clusters. In the UV $(m_{255}, m_{255}-U)$ color magnitude diagram we have discovered a faint `UV-dominant' object. This star lies within the error box of a Low Luminosity Globular Cluster X-ray source (LLGCX) recently found in the core of M92. The properties of the UV star discovered in M92 are very similar to those of other UV stars found in the core of some clusters (M13, 47 Tuc, M80, etc)---all of them are brighter in the UV than in the visible and are located in the vicinity of a LLGCX. We suggest that these stars are a new sub-class of cataclysmic variables.Comment: 21 pages, 4 figures. Astrophysical journal in pres