593 research outputs found
Champagne Flutes and Brandy Snifters: Modelling Protostellar Outflow-Cloud Chemical Interfaces
A rich variety of molecular species has now been observed towards hot cores
in star forming regions and in the interstellar medium. An increasing body of
evidence from millimetre interferometers suggests that many of these form at
the interfaces between protostellar outflows and their natal molecular clouds.
However, current models have remained unable to explain the origin of the
observational bias towards wide-angled "brandy snifter" shaped outflows over
narrower "champagne flute" shapes in carbon monoxide imaging. Furthermore,
these wide-angled systems exhibit unusually high abundances of the molecular
ion HCO. We present results from a chemo-dynamic model of such regions
where a rich chemistry arises naturally as a result of turbulent mixing between
cold, dense molecular gas and the hot, ionized outflow material. The injecta
drives a rich and rapid ion-neutral chemistry in qualitative and quantitative
agreement with the observations. The observational bias towards wide-angled
outflows is explained naturally by the geometry-dependent ion injection rate
causing rapid dissociation of CO in the younger systems.Comment: Accepted to MNRAS. 12 pages, 8 Figure
Bubbles in Planetary Nebulae and Clusters of Galaxies: Instabilities at Bubble Fronts
I study the stability of off-center low-density more or less spherical (fat)
bubbles in clusters of galaxies and in planetary nebulae (PNs) to
Rayleigh-Taylor (RT) instability. As the bubble expands and decelerates, the
interface between the low-density bubble's interior and the dense shell formed
from the accreted ambient medium is RT-stable. If, however, in a specific
direction the density decreases such that this segment is accelerated by the
pressure inside the bubble, then this accelerated region is RT-unstable. The
outermost region, relative to the center of the system, is the most likely to
become unstable because there the density gradient is the steepest. Using
simple analytical analysis, I find that off-center fat bubbles in PNs are much
less stable than in clusters. In PNs bubbles become unstable when they are very
small relative to their distance from the center; they can be stabilized
somewhat if the mass loss rate from the stellar progenitor decreases for a
time, such that the negative density gradient is much shallower. In clusters
fat bubbles become unstable when their size is comparable to their distance
from the center. I discuss some implications of this instability in clusters
and in PNs.Comment: New Astronomy, in press; a third in a series of 3 paper
Receptor-independent metabolism of platelet-activating factor by myelogenous cells
AbstractHuman neutrophils incorporate and metabolize platelet-activating factor (PAF). We dissociated these events from PAF binding to its receptors. Cells were pretreated with either pronase, a PAF antagonist (L652731), or excess PAF. This reduced PAF receptor numbers by 70 to almost 100% but had no comparable effect upon the neutrophil's ability to metabolize PAF. Furthermore, HL-60 cells efficiently metabolized, but did not specifically bind, PAF. Thus, PAF receptor availability did not correlate with PAF metabolic capacity and we conclude that myelogenous tissues can process this bioactive ligand by a receptor-independent pathway
Observatory/data centre partnerships and the VO-centric archive: The JCMT Science Archive experience
We present, as a case study, a description of the partnership between an
observatory (JCMT) and a data centre (CADC) that led to the development of the
JCMT Science Archive (JSA). The JSA is a successful example of a service
designed to use Virtual Observatory (VO) technologies from the start. We
describe the motivation, process and lessons learned from this approach.Comment: Accepted for publication in the second Astronomy & Computing Special
Issue on the Virtual Observatory; 10 pages, 5 figure
Measuring and modeling of GPR ground wave depth penetration under transient soil moisture conditions in
Abstract-This study represents the first attempt to investigate the C;PR direct ground wave sampling depth by comparing GPR estimated soil moisture contents with data from horizontally and vertically installed TDR probes at different depths. The GPR direct ground wave method (200 MHz centre frequency) was used to estimate the temporal soil moisture dependence during uniform irrigation and drainage. Uniform irrigation and drainage experiments were conducted in an experimental pit (2.5 x 1.01 x 0.8 m) filled with repacked sandy loam soil. The GPR moisture contents measurements were more consistent with the moisture contents from vertically installed TDR than horizontally installed TDR. An analytical solution for onedimensional drainage of water was used to estimate the change in GPR ground wave sampling depth during drainage. The analytical solution was first fit to vertical TDR data to obtain an estimate of the soil hydraulic parameters and the GPR sampling depth was then estimated by fitting the drainage solution to the measured GPR data. The GPR direct ground wave sampling depth using the analytical solution during drainage varied from -20 cin at high moisture content to -50 cm at the lowest moisture conten
A Practical Guide of the Southwest Oncology Group to Measure Malignant Pleural Mesothelioma Tumors by RECIST and Modified RECIST Criteria
Abstract:Malignant pleural mesothelioma (MPM) is difficult to measure radiographically due to the nonradial and variable pattern of growth and response to therapy. Inaccurate and inconsistent tumor measurements often compromise results from clinical trials that are dependent on identifying response rate and progression-free survival. In this article, we sought to provide a practical guide through the Southwest Oncology Group on how to measure MPM by the updated RECIST version 1.1 and by modified RECIST. We hope that these steps will provide a simple means by which computed tomography measurements can be consistently performed, minimizing intra- and interobserver variability. With this consistency, we may be able to better estimate the prognosis and response to therapy. With greater utilization, we will be able to better understand the biology of MPM
Sexual health and wellbeing training with women in Pacific Island Countries and Territories: a scoping review
Background:
Women who are spouses of students at a faith-based university in Papua New Guinea (PNG) are afforded proximal power. These women are perceived as leaders and regularly approached by members in their communities to provide advice on sexual and reproductive health matters. Women leaders therefore need access to sexual health information and training to provide appropriate advice.
Objective:
The aim of this paper is to review the characteristics of community-based sexual health training in Pacific Island Countries and Territories (PICTs), as reported in published literature. This is evidence to inform the development of sexual health training programs for women in PNG.
Methods:
A systematic search of databases, repositories and websites identified peer-reviewed studies. Grey literature was also sourced from government and non-government organisations and PNG health professionals. Six published papers, one report, one health worker practice manual and one health worker training package were identified for inclusion. Selected papers were assessed against the Canadian Hierarchy of Evidence to determine quality of evidence for practice. Themes were identified using a thematic analysis approach.
Results:
Three themes became apparent from the literature synthesis: i) program development; ii) mode of delivery, and iii) evaluation. Social and cultural context influenced all elements of sexual health training in PICTs. Few studies reported evidence of comprehensive evaluation.
Conclusions:
Successful sexual health training programs in PICT communities are designed and delivered accounting for local contexts. Programs that engage participants with diverse abilities inspire change to achieve desired outcomes. Key findings from this study can be used to assist women leaders to contextualise and operationalise sexual health training to promote the wellbeing of members in their communities
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