3,542 research outputs found

    Large Magnetic Fields and Motions of OH Masers in W75 N

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    We report on a second epoch of VLBA observations of the 1665 and 1667 MHz OH masers in the massive star-forming region W75 N. We find evidence to confirm the existence of very strong (~40 mG) magnetic fields near source VLA 2. The masers near VLA 2 are dynamically distinct and include a very bright spot apparently moving at 50 km/s relative to those around VLA 1. This fast-moving spot may be an example of a rare class of OH masers seen in outflows in star-forming regions. Due to the variability of these masers and the rapidity of their motions, tracking these motions will require multiple observations over a significantly shorter time baseline than obtained here. Proper motions of the masers near VLA 1 are more suggestive of streaming along magnetized shocks rather than Keplerian rotation in a disk. The motions of the easternmost cluster of masers in W75 N (B) may be tracing slow expansion around an unseen exciting source.Comment: 7 pages including 4 figures (2 color) & 3 tables, to appear in Ap

    Root pruning, wrenching and overwinter cold storage : effects on the morphological and physiological condition of transplant Picea glauca [Moench] Voss nursery stock

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    The objectives of this thesis were to; 1) evaluate the effect of a single early spring root pruning followed by a series of five root wrenching treatments at three week intervals on the morphological condition of rising 2+2 white spruce nursery stock, 2) to determine the effect of wrenching and several overwinter cold storage environments on bud dormancy progression, root regenerating potential and planting stock performance, 3) to assess wrenching as a method of conditioning bare root nursery stock for fall lifting and overwinter cold storage. Root pruning and wrenching was applied to rising 2+2 white spruce in nursery trials one in 1982 and another in 1983 at the Ontario Ministry of Natural Resources Forest Station, Thunder Bay Ontario. The root pruning and wrenching treatment reduced current height increment, reduced the number of primordia in the winter buds, and in 1983 significantly increased root area index. Root pruning and wrenching increased the overall root regenerating potential of stock during overwinter cold storage. Wrenching and root pruning did not significantly alter bud dormancy progression or patterns of root regeneration during the winter. Both the control and the root pruned and wrenched stock was overwinter cold stored in 3 storage environments. The progression of bud dormancy and root regeneration potential of this stock was monitored monthly for a seven month period during the winter. Stock that was fall lifted and overwinter stored had the same winter bud dormancy pattern as stock overwintered in the nursery bed but a different pattern of root regenerating potential. Cold storage delayed bud flushing in the spring and prevented frost damage from occuring after spring outplanting. A six week spring warm up conditioning treatment at +2 C in cold storage increased root regenerating potential. The exposure of fall lifted stock to natural photoperiods while overwintering in an unheated polyhouse did not appear to improve planting stock quality over that of the same stock overwintered at -2 C in complete darkness

    The Ursinus Weekly, March 18, 1940

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    Board elects Nicholas T. Barry new Ursinus Weekly editor • Weiland to edit 1941 Ruby ; Dubuque is business manager • Law and morals Goodrich\u27s subject • Candidates listed for April elections • C.A. Kulp talks on old-age security • Jr. ticket committee explains special price • Snyder sets April 2 for spring Lantern issue • Members of faculty quizzed in poll express sentiments on third term • 21-year voting age favored by students • Party is planned for conference week-end • I.R.C. quizzed on current events; will admit members • Committee heads are selected for women\u27s May Day pageant • Hal Moyer chosen honorary basketball captain for season • Ursinus players on all-star quintets • Infield and outfield candidates report • Dorm battlers vie Wednesday in gym • Frosh won five of twelve games • John DeBold wins conference trophy • Undefeated Temple beaten by co-eds • Conference committee secures two speakers • Vespers speaker points way to achieve true personality • Temple professor to address pre-medical society Tuesdayhttps://digitalcommons.ursinus.edu/weekly/1838/thumbnail.jp

    Usefulness of electrophysiologic study to determine the clinical tolerance of arrhythmia recurrences during amiodarone therapy

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    The relation of clinical and electrophysiologic variables to outcome was evaluated in 121 patients treated with amiodarone for sustained ventricular tachyarrhythmias. Electrophysiologic study was performed in all patients a mean of 14 days after beginning amiodarone therapy. Forty-six patients who were given oral amiodarone therapy experienced arrhythmia recurrence. Multivariate analysis was performed using 16 clinical and electrophysiologic variables to determine which factors were associated with 1) arrhythmia recurrence and 2) a poorly tolerated arrhythmia recurrence (that is, cardiac arrest or sudden cardiac death) during oral amiodarone therapy. No variable predicted arrhythmia recurrence. Five variables correlated significantly with a poorly tolerated arrhythmia recurrence. Hemodynamic stability of the arrhythmia induced on electrophysiologic testing during amiodarone therapy had the best predictive value (p < 0.001). Younger age, lower ejection fraction, a poorly tolerated rhythm at clinical presentation and absence of left ventricular aneurysm were also associated with a poorly tolerated arrhythmia recurrence.Only 3 of 57 patients who had a well tolerated arrhythmia induced on electrophysiologic testing during amiodarone therapy had recurrence of a poorly tolerated arrhythmia versus 19 of 47 who had hemodynamically unstable arrhythmias induced during amiodarone therapy (p < 0.001). Thus, electrophysiologic testing during amiodarone therapy appears useful in identifying patients who are prone to have catastrophic arrhythmia recurrences and could allow for the institution of additional or alternative modes of therapy

    The Spitzer c2d Survey of Nearby Dense Cores: VI. The Protostars of Lynds Dark Nebula 1221

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    Observations of Lynds Dark Nebula 1221 from the Spitzer Space Telescope are presented. These data show three candidate protostars towards L1221, only two of which were previously known. The infrared observations also show signatures of outflowing material, an interpretation which is also supported by radio observations with the Very Large Array. In addition, molecular line maps from the Five College Radio Astronomy Observatory are shown. One-dimensional dust continuum modelling of two of these protostars, IRS1 and IRS3, is described. These models show two distinctly different protostars forming in very similar environments. IRS1 shows a higher luminosity and larger inner radius of the envelope than IRS3. The disparity could be caused by a difference in age or mass, orientation of outflow cavities, or the impact of a binary in the IRS1 core.Comment: accepted for publication in Ap

    Density Variations in the NW Star Stream of M31

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    The Pan Andromeda Archeological Survey (PAndAS) CFHT Megaprime survey of the M31-M33 system has found a star stream which extends about 120 kpc NW from the center of M31. The great length of the stream, and the likelihood that it does not significantly intersect the disk of M31, means that it is unusually well suited for a measurement of stream gaps and clumps along its length as a test for the predicted thousands of dark matter sub-halos. The main result of this paper is that the density of the stream varies between zero and about three times the mean along its length on scales of 2 to 20 kpc. The probability that the variations are random fluctuations in the star density is less than 10^-5. As a control sample we search for density variations at precisely the same location in stars with metallicity higher than the stream, [Fe/H]=[0, -0.5] and find no variations above the expected shot noise. The lumpiness of the stream is not compatible with a low mass star stream in a smooth galactic potential, nor is it readily compatible with the disturbance caused by the visible M31 satellite galaxies. The stream's density variations appear to be consistent with the effects of a large population of steep mass function dark matter sub-halos, such as found in LCDM simulations, acting on an approximately 10Gyr old star stream. The effects of a single set of halo substructure realizations are shown for illustration, reserving a statistical comparison for another study.Comment: ApJ revised version submitte

    The Ursinus Weekly, December 11, 1939

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    Communion and party in gym will feature Christmas week • Snyder plans new Lantern make-up • Messiah pleases capacity audience • Wood to head interfraternity-sorority dance on January 13 • McClures to entertain women tonight and tomorrow evening • 13 members added to Weekly staff • Sr. play portrays conflicts of Irish Catholicism • Senior ball draws 140 couples to dance to Gordon\u27s orchestra • Russo-Finnish conflict to be discussed by Herber at IRC • Pres. McClure will speak to Brotherhood at meeting Tuesday • Students reveal opinion on editorial comments • First I.R.C. Quarterly under Yoh released • Student poll describes ideal Ursinus professor • Veteran five ready to open season against Rutgers at New Brunswick Saturday; Chern, Keehn will swap posts • Co-ed basketeers down Rosemont in exhibition • The fall seasons in review: football and soccer • Frosh court candidates begin practice tonight • Collection of Madonnas is exhibited in libraryhttps://digitalcommons.ursinus.edu/weekly/1830/thumbnail.jp

    MUSTANG 3.3 Millimeter Continuum Observations of Class 0 Protostars

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    We present observations of six Class 0 protostars at 3.3 mm (90 GHz) using the 64-pixel MUSTANG bolometer camera on the 100-m Green Bank Telescope. The 3.3 mm photometry is analyzed along with shorter wavelength observations to derive spectral indices (S_nu ~ nu^alpha) of the measured emission. We utilize previously published dust continuum radiative transfer models to estimate the characteristic dust temperature within the central beam of our observations. We present constraints on the millimeter dust opacity index, beta, between 0.862 mm, 1.25 mm, and 3.3 mm. Beta_mm typically ranges from 1.0 to 2.4 for Class 0 sources. The relative contributions from disk emission and envelope emission are estimated at 3.3 mm. L483 is found to have negligible disk emission at 3.3 mm while L1527 is dominated by disk emission within the central beam. The beta_mm^disk <= 0.8 - 1.4 for L1527 indicates that grain growth is likely occurring in the disk. The photometry presented in this paper may be combined with future interferometric observations of Class 0 envelopes and disks.Comment: 19 pages, 3 figures, AJ accepted, in pres
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