247 research outputs found
Morphologies of Ultracompact HII Regions in W49A and Sgr B2: Prevalence of Shells and a Modified Classification Scheme
We have used Very Large Array (VLA) observations of the massive star forming
regions W49A and Sgr B2, obtained with resolutions from 2\farcs0 to 0\farcs04,
to classify the morphologies of nearly 100 ultracompact HII regions. These high
resolution, multi-frequency, multi-configuration VLA observations motivate
several modifications of the existing morphological classification scheme for
UC HII regions. In this work, we describe the modified morphology scheme and
the criteria used in source classification. In particular, we drop the
``core-halo'' classification, add a ``bipolar'' classification, and change the
shell classification to ``shell-like''. We tally the percentage of each
morphology found in the Sgr B2 and W49A regions and find broad agreement with
the Galactic plane surveys in the distribution of morphologies for most types.
However, we find that nearly a third of the sources in these regions are
shell-like, which is a higher percentage by nearly a factor of ten than found
in the surveys of Galactic plane star forming regions by Wood & Churchwell
(1989a) and Kurtz et al. (1994). This difference may be due to physical
differences in the environments of these two extreme star forming regions.
Alternatively, differences in observational technique may be responsible.Comment: 10 pages, 1 figure, 1 table, to appear in The Astrophysical Journal
Letter
Identification of protein interactions of grapevine fanleaf virus RNA-dependent RNA polymerase during infection of by affinity purification and tandem mass spectrometry.
The RNA-dependent RNA polymerase (1E) is involved in replication of grapevine fanleaf virus (GFLV, , ) and causes vein clearing symptoms in . Information on protein 1E interaction with other viral and host proteins is scarce. To study protein 1E biology, three GFLV infectious clones, i.e. GHu (a symptomatic wild-type strain), GHu-1E (an asymptomatic GHu mutant) and F13 (an asymptomatic wild-type strain), were engineered with protein 1E fused to a V5 epitope tag at the C-terminus. Following -mediated delivery of GFLV clones in and protein extraction at seven dpi, when optimal 1E:V5 accumulation was detected, two viral and six plant putative interaction partners of V5-tagged protein 1E were identified for the three GFLV clones by affinity purification and tandem mass spectrometry. This study provides insights into the protein interactome of 1E during GFLV systemic infection in and lays the foundation for validation work
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Nonperturbative-transverse-momentum broadening in dihadron angular correlations in sNN =200 GeV proton-nucleus collisions
The PHENIX collaboration has measured high-pT dihadron correlations in p+p, p+Al, and p+Au collisions at sNN=200 GeV. The correlations arise from inter- and intrajet correlations and thus have sensitivity to nonperturbative effects in both the initial and final states. The distributions of pout, the transverse-momentum component of the associated hadron perpendicular to the trigger hadron, are sensitive to initial- and final-state transverse momenta. These distributions are measured multidifferentially as a function of xE, the longitudinal momentum fraction of the associated hadron with respect to the trigger hadron. The near-side pout widths, sensitive to fragmentation transverse momentum, show no significant broadening between p+Au, p+Al, and p+p. The away-side nonperturbative pout widths are found to be broadened in p+Au when compared to p+p; however, there is no significant broadening in p+Al compared to p+p collisions. The data also suggest that the away-side pout broadening is a function of Ncoll, the number of binary nucleon-nucleon collisions, in the interaction. The potential implications of these results with regard to initial- and final-state transverse-momentum broadening and energy loss of partons in a nucleus, among other nuclear effects, are discussed
Nuclear dependence of the transverse single-spin asymmetry in the production of charged hadrons at forward rapidity in polarized , Al, and Au collisions at GeV
We report on the nuclear dependence of transverse single-spin asymmetries
(TSSAs) in the production of positively-charged hadrons in polarized
, Al and Au collisions at
GeV. The measurements have been performed at forward
rapidity () over the range of GeV and
. We observed a positive asymmetry for
positively-charged hadrons in \polpp collisions, and a significantly reduced
asymmetry in + collisions. These results reveal a nuclear
dependence of charged hadron in a regime where perturbative techniques
are relevant. These results provide new opportunities to use \polpA collisions
as a tool to investigate the rich phenomena behind TSSAs in hadronic collisions
and to use TSSA as a new handle in studying small-system collisions.Comment: 303 authors from 66 institutions, 9 pages, 2 figures, 1 table. v1 is
version accepted for publication in Physical Review Letters. Plain text data
tables for the points plotted in figures for this and previous PHENIX
publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
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