2,496 research outputs found
The effect of FK 506 on peripheral blood T-lymphocyte subsets in orthotopic liver transplant patients
Study of Interaction between Plasma and EM Wave in Prospect of Application of Millimeter & Sub-millimeter Waves
Study of Interaction between Plasma and EM Wave in Prospect of Application of Millimeter & Sub-millimeter Waves
Star Formation in Bright Rimmed Clouds. I. Millimeter and Submillimeter Molecular Line Surveys
We present the results of the first detailed millimeter and submillimeter
molecular line survey of bright rimmed clouds, observed at FCRAO in the CO
(J=1-0), C18O (J=1-0), HCO+ (J=1-0), H13CO+ (J=1-0), and N2H+ (J=1-0)
transitions, and at the HHT in the CO (J=2-1), HCO+ (J=3-2), HCO+ (J=4-3),
H13CO+ (J=3-2), and H13CO+ (J=4-3) molecular line transitions. The source list
is composed of a selection of bright rimmed clouds from the catalog of such
objects compiled by Sugitani et al. (1991). We also present observations of
three Bok globules done for comparison with the bright rimmed clouds. We find
that the appearance of the millimeter CO and HCO+ emission is dominated by the
morphology of the shock front in the bright rimmed clouds. The HCO+ (J=1-0)
emission tends to trace the swept up gas ridge and overdense regions which may
be triggered to collapse as a result of sequential star formation. Five of the
seven bright rimmed clouds we observe seem to have an outflow, however only one
shows the spectral line blue-asymmetric signature that is indicative of infall,
in the optically thick HCO+ emission. We also present evidence that in bright
rimmed clouds the nearby shock front may heat the core from outside-in thereby
washing out the normally observed line infall signatures seen in isolated star
forming regions. We find that the derived core masses of these bright rimmed
clouds are similar to other low and intermediate mass star forming regions.Comment: 67 pages, including 35 figures and 6 tables. Accepted for publication
in ApJ. Version with embedded full-resolution figures available at
http://www.astro.umass.edu/~devries/brc1
Embedded Stellar Clusters in the W3/W4/W5 Molecular Cloud Complex
We analyze the embedded stellar content in the vicinity of the W3/W4/W5 HII
regions using the FCRAO Outer Galaxy 12CO(J=1-0) Survey, the IRAS Point Source
Catalog, published radio continuum surveys, and new near-infrared and molecular
line observations. Thirty-four IRAS Point Sources are identified that have
far-infrared colors characteristic of embedded star forming regions, and we
have obtained K' mosaics and 13CO(J=1-0) maps for 32 of them. Ten of the IRAS
sources are associated with an OB star and 19 with a stellar cluster, although
three OB stars are not identified with a cluster. Half of the embedded stellar
population identified in the K' images is found in just the 5 richest clusters,
and 61% is contained in IRAS sources associated with an embedded OB star. Thus
rich clusters around OB stars contribute substantially to the stellar
population currently forming in the W3/W4/W5 region. Approximately 39% of the
cluster population is embedded in small clouds with an average mass of ~130 Mo
that are located as far as 100 pc from the W3/W4/W5 cloud complex. We speculate
that these small clouds are fragments of a cloud complex dispersed by previous
episodes of massive star formation. Finally, we find that 4 of the 5 known
embedded massive star forming sites in the W3 molecular cloud are found along
the interface with the W4 HII region despite the fact that most of the
molecular mass is contained in the interior regions of the cloud. These
observations are consistent with the classical notion that the W4 HII region
has triggered massive star formation along the eastern edge of the W3 molecular
cloud.Comment: to appear in ApJS, see http://astro.caltech.edu/~jmc/papers/w
Study of Interaction between Plasma and EM Wave in Prospect of Application of Millimeter & Sub-millimeter Waves ? Linear Analysis of Global Structure of Drift Wave ?
Quasi-Solitons in Dissipative Systems and Exactly Solvable Lattice Models
A system of first-order differential-difference equations with time lag
describes the formation of density waves, called as quasi-solitons for
dissipative systems in this paper. For co-moving density waves, the system
reduces to some exactly solvable lattice models. We construct a shock-wave
solution as well as one-quasi-soliton solution, and argue that there are
pseudo-conserved quantities which characterize the formation of the co-moving
waves. The simplest non-trivial one is given to discuss the presence of a
cascade phenomena in relaxation process toward the pattern formation.Comment: REVTeX, 4 pages, 1 figur
Three-Dimensional X-ray Observation of Atmospheric Biological Samples by Linear-Array Scanning-Electron Generation X-ray Microscope System
Recently, we developed a soft X-ray microscope called the scanning-electron generation X-ray microscope (SGXM), which consists of a simple X-ray detection system that detects X-rays emitted from the interaction between a scanning electron beam (EB) and the thin film of the sample mount. We present herein a three-dimensional (3D) X-ray detection system that is based on the SGXM technology and designed for studying atmospheric biological samples. This 3D X-ray detection system contains a linear X-ray photodiode (PD) array. The specimens are placed under a CuZn-coated Si3N4 thin film, which is attached to an atmospheric sample holder. Multiple tilt X-ray images of the samples are detected simultaneously by the linear array of X-ray PDs, and the 3D structure is calculated by a new 3D reconstruction method that uses a simulated-annealing algorithm. The resulting 3D models clearly reveal the inner structure of the bacterium. In addition, the proposed method can easily be used for diverse samples in a broad range of scientific fields
New Herbig-Haro Objects and Giant Outflows in Orion
We present the results of a photographic and CCD imaging survey for
Herbig-Haro (HH) objects in the L1630 and L1641 giant molecular clouds in
Orion. The new HH flows were initially identified from a deep H-alpha film from
the recently commissioned AAO/UKST H-alpha Survey of the southern sky. Our
scanned H-alpha and broad band R images highlight both the improved resolution
of the H-alpha survey and the excellent contrast of the H-alpha flux with
respect to the broad band R. Comparative IVN survey images allow us to
distinguish between emission and reflection nebulosity. Our CCD H-alpha, [SII],
continuum and I band images confirm the presence of a parsec-scale HH flow
associated with the Ori I-2 cometary globule and several parsec-scale strings
of HH emission centred on the L1641-N infrared cluster. Several smaller
outflows display one-sided jets. Our results indicate that for declinations
south of -6 degrees in L1641, parsec-scale flows appear to be the major force
in the large-scale movement of optical dust and molecular gas.Comment: 14 pages, Latex using MN style, 21 figures in JPEG format. Higher
resolution figures available from S.L. Mader. Accepted by MNRAS. Email
contact for higher resolution images: [email protected]
- …