3,542 research outputs found
Large Magnetic Fields and Motions of OH Masers in W75 N
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
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
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
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Endocytotic formation of vesicles and other membranous structures induced by Ca2+ and axolemmal injury
Vesicles and/or other membranous structures that form after
axolemmal damage have recently been shown to repair (seal)
the axolemma of various nerve axons. To determine the origin
of such membranous structures, (1) we internally dialyzed isolated
intact squid giant axons (GAs) and showed that elevation
of intracellular Ca21 .100 uM produced membranous structures
similar to those in axons transected in Ca21-containing
physiological saline; (2) we exposed GA axoplasm to Ca21-
containing salines and observed that membranous structures
did not form after removing the axolemma and glial sheath but
did form in severed GAs after .99% of their axoplasm was
removed by internal perfusion; (3) we examined transected GAs
and crayfish medial giant axons (MGAs) with time-lapse confocal
fluorescence microscopy and showed that many injuryinduced
vesicles formed by endocytosis of the axolemma; (4)
we examined the cut ends of GAs and MGAs with electron
microscopy and showed that most membranous structures
were single-walled at short (5–15 min) post-transection times,
whereas more were double- and multi-walled and of probable
glial origin after longer (30–150 min) post-transection times; and
(5) we examined differential interference contrast and confocal
images and showed that large and small lesions evoked similar
injury responses in which barriers to dye diffusion formed amid
an accumulation of vesicles and other membranous structures.
These and other data suggest that Ca21 inflow at large or small
axolemmal lesions induces various membranous structures (including
endocytotic vesicles) of glial or axonal origin to form,
accumulate, and interact with each other, preformed vesicles,
and/or the axolemma to repair the axolemmal damage.This work was supported by grants from National Institutes of Health (NIH;
NS31256) and the State of Texas (Advanced Technology 3658-446).Neuroscienc
Usefulness of electrophysiologic study to determine the clinical tolerance of arrhythmia recurrences during amiodarone therapy
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
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
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
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
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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Repowering with clean coal technologies
Repowering with clean coal technology can offer significant advantages, including lower heat rates and production costs, environmental compliance, incremental capacity increases, and life extension of existing facilities. Significant savings of capital costs can result by refurbishing and reusing existing sites and infrastructure relative to a greenfield siting approach. This paper summarizes some key results of a study performed by Parsons Power Group, Inc., under a contract with DOE/METC, which investigates many of the promising advanced power generation technologies in a repowering application. The purpose of this study was to evaluate the technical and economic results of applying each of a menu of Clean Coal Technologies in a repowering of a hypothetical representative fossil fueled power station. Pittsburgh No. 8 coal is used as the fuel for most of the cases evaluated herein, as well as serving as the fuel for the original unrepowered station. The steam turbine-generator, condenser, and circulating water system are refurbished and reused in this study, as is most of the existing site infrastructure such as transmission lines, railroad, coal yard and coal handling equipment, etc. The technologies evaluated in this study consisted of an atmospheric fluidized bed combustor, several varieties of pressurized fluid bed combustors, several types of gasifiers, a refueling with a process derived fuel, and, for reference, a natural gas fired combustion turbine-combined cycle
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