47 research outputs found
A Sample of [CII] Clouds Tracing Dense Clouds in Weak FUV Fields observed by Herschel
The [CII] fine--structure line at 158um is an excellent tracer of the warm
diffuse gas in the ISM and the interfaces between molecular clouds and their
surrounding atomic and ionized envelopes. Here we present the initial results
from Galactic Observations of Terahertz C+ (GOTC+), a Herschel Key Project
devoted to study the [CII] fine structure emission in the galactic plane using
the HIFI instrument. We use the [CII] emission together with observations of CO
as a probe to understand the effects of newly--formed stars on their
interstellar environment and characterize the physical and chemical state of
the star-forming gas. We collected data along 16 lines--of--sight passing near
star forming regions in the inner Galaxy near longitudes 330 degrees and 20
degrees. We identify fifty-eight [CII] components that are associated with
high--column density molecular clouds as traced by 13CO emission. We combine
[CII], 12CO, and 13CO observations to derive the physical conditions of the
[CII]--emitting regions in our sample of high--column density clouds based on
comparison with results from a grid of Photon Dominated Region (PDR) models.
From this unbiased sample, our results suggest that most of [CII] emission
originates from clouds with H2 volume densities between 10e3.5 and 10e5.5 cm^-3
and weak FUV strength (CHI_0=1-10). We find two regions where our analysis
suggests high densities >10e5 cm^-3 and strong FUV fields (CHI=10e4-10e6),
likely associated with massive star formation. We suggest that [CII] emission
in conjunction with CO isotopes is a good tool to differentiate between regions
of massive star formation (high densities/strong FUV fields) and regions that
are distant from massive stars (lower densities/weaker FUV fields) along the
line--of--sightComment: To be published in A&A HIFI Special Editio
ROLE OF NUTRITIONAL INTERVENTION ON REVERSAL OF FETAL DUCTAL CONSTRICTION CAUSED BY MATERNAL INGESTION OF POLYPHENOL-RICH FOODS
Southern Galactic Plane Survey Measurements of the Spatial Power Spectrum of Interstellar H I in the Inner Galaxy
Using data from the Southern Galactic Plane Survey we have measured the
spatial power spectrum of the interstellar neutral atomic hydrogen in the
fourth Galactic quadrant. This function shows the same power law behavior that
has been found for H I in the second quadrant of the Milky Way and in the
Magellanic Clouds, with the same slope. When we average over velocity intervals
broader than the typical small-scale velocity dispersion, we find that the
slope steepens, from approx. -3 to -4 for the warm gas, as predicted by
theories of interstellar turbulence if the column density fluctuations are
dominated by variations in the gas density on small spatial scales. The cool
gas shows a different increase of slope, that suggests that it is in the regime
of turbulence dominated by fluctuations in the velocity field. Overall, these
results confirm that the small scale structure and motions in the neutral
atomic medium are well described by a turbulent cascade of kinetic energy.Comment: 20 pages with 8 figures, LaTeX. Accepted by Ap. J. (scheduled for ApJ
Vol. 561 num. 2, November 10, 2001
How to Search for Doubly Charmed Baryons and Tetraquarks
Possible experimental searches of doubly charmed baryons and tetraquarks at
fixed target experiments with high energy hadron beams and a high intensity
spectrometer are considered here. The baryons considered are:
(ccd), (ccu), and (ccs); and the tetraquark
is T (). Estimates are given of masses, lifetimes, internal
structure, production cross sections, decay modes, branching ratios, and
yields. Experimental requirements are given for optimizing the signal and
minimizing the backgrounds. The discussion is in the spirit of an experimental
and theoretical review, as part of the planning for a CHarm Experiment with
Omni-Purpose Setup (CHEOPS) at CERN. The CHEOPS objective is to achieve a
state-of-the-art very charming experiment, in the spirit of the aims of the
recent CHARM2000 workshop.Comment: 18 pages text (latex), 16 March 1995, presented at "Physics with
Hadron Beams with a High Intensity Spectrometer", revised 10 May for more
complete bibliography and appropriate references to S. Paul et al., Letter of
Intent, CHEOPS
Genetic Diversity and Structure of the Fisher (Martes Pennanti) in a Peninsular and Peripheral Metapopulation
Evolutionary processes can be strongly affected by landscape features. In vagile carnivores that disperse widely, however, genetic structure has been found to be minimal. Using microsatellite DNA primers developed for other mustelids, we found that populations of a vagile forest carnivore, the fisher (Martes pennanti), exhibit high genetic structure (FST = 0.45, SE = 0.07) and limited gene flow (Nm \u3c 1) within a .1,600-km narrow strip of forested habitat; that genetic diversity decreases from core to periphery; and that populations do not show an equilibrium pattern of isolation-by-distance. Genetic structure was greater at the periphery than at the core of the distribution and our data fit a 1-dimensional model of stepping-stone range expansion. Multiple lines of paleontological and genetic evidence suggest that the fisher recently (\u3c5,000 years ago) expanded into the mountain forests of the Pacific coast. The reduced dimensionality of the distribution of the fisher in western coastal forests appears to have contributed to the high levels of structure and decreasing diversity from north to south. These effects were likely exacerbated by human-caused changes to the environment. The low genetic diversity and high genetic structure of populations in the southern Sierra Nevada suggest that populations in this part of the geographic range are vulnerable to extinction