1,722,906 research outputs found
1946 Neal J. Johnson 165 lbs.
No full textAlt Text: Headshot of 1946 165 pound wrestler Neal J. Johnson. He wears a white singlet. Black and white image.https://scholarworks.uni.edu/panther_athletics/2146/thumbnail.jp
Applied econometric essays on sales taxes and computer price indices
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Economics, 1994.Includes bibliographical references.by Neal J. Rappaport.Ph.D
The Gould Belt "Misfits" Survey: The Real Solar Neighborhood Protostars
Full text linkWe present an HCO+ J = 3. 2 survey of Class 0+I and Flat SED young stellar objects (YSOs) found in the Gould Belt clouds by surveys with Spitzer. Our goal is to provide a uniform Stage 0+I source indicator for these embedded protostar candidates. We made single point HCO+J = 3 -> 2 measurements toward the source positions at the CSO and APEX of 546 YSOs (89% of the Class 0+I +Flat SED sample). Using the criteria from van Kempen et al., we classify sources as Stage 0+I or bona fide protostars and find that 84% of detected sources meet the criteria. We recommend a timescale for the evolution of Stage 0+I (embedded protostars) of 0.54 Myr. We find significant correlations of HCO+integrated intensity with a and Tbol but not with Lbol. The detection fraction increases smoothly as a function of a and Lbol, while decreasing smoothly with Tbol. Using the Stage 0+I sources tightens the relation between protostars and high extinction regions of the cloud; 89% of Stage I sources lie in regions with A(V) > 8 mag. Class 0+I and Flat SED YSOs that are not detected in HCO+ have, on average, a factor of similar to 2 higher Tbol and a factor of similar to 5 lower L-bol than YSOs with HCO+ detections. We find less YSO contamination, defined as the number of undetected YSOs divided by the total number surveyed, for sources with T-bol less than or similar to 600 K and L-bol greater than or similar to 1 L-circle dot. The contamination percentage is > 90% at A(V) < 4 mag and decreases as A(V) increases.NSF AAPF AST-1302978NSF AST-1109116Astronom
Testing 24 mu m And Infrared Luminosity As Star Formation Tracers For Galactic Star-Forming Regions
Full text linkWe have tested some relations for star formation rates used in extragalactic studies for regions within the Galaxy. In nearby molecular clouds, where the initial mass function is not fully sampled, the dust emission at 24 mu m greatly underestimates star formation rates (by a factor of 100 on average) when compared to star formation rates determined from counting young stellar objects. The total infrared emission does no better. In contrast, the total far-infrared method agrees within a factor of two on average with star formation rates based on radio continuum emission for massive, dense clumps that are forming enough massive stars to have L-TIR exceed 10(4.5) L-circle dot. The total infrared and 24 mu m also agree well with each other for both nearby, low-mass star-forming regions and the massive, dense clump regions.NSF AST-1109116Astronom
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
HEALTH PROGRAMS FOR DAIRY HEIFERS
No full textArnes, Trevor R.; Sivula, Neal J.; Marsh, Will E.. (1995). HEALTH PROGRAMS FOR DAIRY HEIFERS. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/118780
Properties Of The Youngest Protostars In Perseus, Serpens, And Ophiuchus
Full text linkWe present an unbiased census of deeply embedded protostars in Perseus, Serpens, and Ophiuchus, assembled by combining large-scale 1.1 mm Bolocam continuum and Spitzer Legacy surveys. We identify protostellar candidates based on their mid-infrared (mid-IR) properties, correlate their positions with 1.1 mm core positions from Enoch et al. in 2006 and 2007, and Young et al. in 2006, and construct well-sampled spectral energy distributions using our extensive wavelength coverage (lambda = 1.25-1100 mu m). Source classification based on the bolometric temperature yields a total of 39 Class 0 and 89 Class I sources in the three-cloud sample. We compare to protostellar evolutionary models using the bolometric temperature-luminosity diagram, finding a population of low-luminosity Class I sources that are inconsistent with constant or monotonically decreasing mass accretion rates. This result argues strongly for episodic accretion during the Class I phase, with more than 50% of sources in a "sub-Shu" (dM/dt < 10(-6)M(circle dot) yr(-1)) accretion state. Average spectra are compared to protostellar radiative transfer models, which match the observed spectra fairly well in Stage 0, but predict too much near-IR and too little mid-IR flux in Stage I. Finally, the relative number of Class 0 and Class I sources is used to estimate the lifetime of the Class 0 phase; the three-cloud average yields a Class 0 lifetime of 1.7 +/- 0.3 x 10(5) yr, ruling out an extremely rapid early accretion phase. Correcting photometry for extinction results in a somewhat shorter lifetime (1.1 x 10(5) yr). In Ophiuchus, however, we find very few Class 0 sources (N(Class0)/N(Class I) similar to 0.1-0.2), similar to previous studies of that cloud. The observations suggest a consistent picture of nearly constant average accretion rate through the entire embedded phase, with accretion becoming episodic by at least the Class I stage, and possibly earlier.NASA Origins NNG04GG24G, NNX07A72GNSF AST-9980846, AST-0206158Astronom
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