242 research outputs found
Carbon in different phases ([CII], [CI], and CO) in infrared dark clouds: Cloud formation signatures and carbon gas fractions
Context: How do molecular clouds form out of the atomic phase? And what are
the relative fractions of carbon in the ionized, atomic and molecular phase?
These are questions at the heart of cloud and star formation. Methods: Using
multiple observatories from Herschel and SOFIA to APEX and the IRAM 30m
telescope, we mapped the ionized, atomic and molecular carbon ([CII]@1900GHz,
[CI]@492GHz and C18O(2-1)@220GHz) at high spatial resolution (12"-25") in four
young massive infrared dark clouds (IRDCs). Results: The three carbon phases
were successfully mapped in all four regions, only in one source the [CII] line
remained a non-detection. Both the molecular and atomic phases trace the dense
structures well, with [CI] also tracing material at lower column densities.
[CII] exhibits diverse morphologies in our sample, from compact to diffuse
structures probing the cloud environment. In at least two out of the four
regions, we find kinematic signatures strongly indicating that the dense gas
filaments have formed out of a dynamically active and turbulent
atomic/molecular cloud, potentially from converging gas flows. The
atomic-to-molecular carbon gas mass ratios are low between 7% and 12% with the
lowest values found toward the most quiescent region. In the three regions
where [CII] is detected, its mass is always higher by a factor of a few than
that of the atomic carbon. The ionized carbon emission depends as well on the
radiation field, however, we also find strong [CII] emission in a region
without significant external sources, indicating that other processes, e.g.,
energetic gas flows can contribute to the [CII] excitation as well.Comment: 15 pages, 18 figures, accepted by Astronomy & Astrophysics, a higher
resolution version can be found at
http://www.mpia.de/homes/beuther/papers.htm
Effectiveness of Occupational Therapy’s Role in Promotion of Role Fulfillment with Aviation Students in Higher Education who are Experiencing Mental Health Conditions
This critically appraised topic paper focuses on occupational therapy’s role and the interventions for improving the mental health of aviation students in higher education. Aviation students are higher education student pilots learning to become pilots within various roles. Stress and fatigue among students in higher education are prominent problems (Beiter, 2015; Kalmakis et al., 2021). The focus on aviation students for this critically appraised topic paper reveals the unique stressors relating to flight training that is added on top of the normal academic stress load that university students face (Robertson & Ruiz, 2010). Due to these stress factors, the mental health of aviation students is negatively impacted and can affect their role fulfillment as aviation students. Higher level education has been defined in this critically appraised topic paper as institutions providing study beyond the level of secondary education, such as colleges and universities, community colleges, and vocational and technical schools (National Center on Safe Supportive Learning Environments, 2023)
Primer for Experimental Methods in Organization Theory
Experiments have long played a crucial role in various scientific disciplines and have been gaining ground in organization theory, where they add unique value by establishing causality and uncovering theoretical mechanisms. This essay provides an overview of the merits and procedures of the experimental methodology, with an emphasis on its application to organization theory. Drawing on the historical roots of experiments and their impact across science, we argue the method holds immense potential for furthering organization theory. We highlight key advantages of experimental methods, including high internal and construct validity, vividness in communicating findings, the capacity to examine complex and understudied phenomena, and the identification of microfoundations and theoretical mechanisms. We alleviate some concerns about external validity and offer guidance for designing and conducting sound, reproducible experimental research. Ultimately, we contend that the current experimental turn holds the potential to reorient organization theory. History: This paper has been accepted for the Organization Science Special Issue on Experiments in Organizational Theory. Funding: This work was supported by the Otto Moensted Foundation, which granted the Otto Moensted Visiting Professorship to S. S. Levine, and a National Science Foundation CAREER Award from the Directorate for Social, Behavioral and Economic Sciences [Grant 1943688] to O. Schilke. Supplemental Material: The online appendix is available at https://doi.org/10.1287/orsc.2023.18093
A spectral line survey of Orion KL in the bands 486-492 and 541-577 GHz with the Odin satellite I. The observational data
Spectral line surveys are useful since they allow identification of new
molecules and new lines in uniformly calibrated data sets. Nonetheless, large
portions of the sub-millimetre spectral regime remain unexplored due to severe
absorptions by H2O and O2 in the terrestrial atmosphere. The purpose of the
measurements presented here is to cover wavelength regions at and around 0.55
mm -- regions largely unobservable from the ground. Using the Odin
astronomy/aeronomy satellite, we performed the first spectral survey of the
Orion KL molecular cloud core in the bands 486--492 and 541--576 GHz with
rather uniform sensitivity (22--25 mK baseline noise). Odin's 1.1 m size
telescope, equipped with four cryo-cooled tuneable mixers connected to broad
band spectrometers, was used in a satellite position-switching mode. Two mixers
simultaneously observed different 1.1 GHz bands using frequency steps of 0.5
GHz (25 hours each). An on-source integration time of 20 hours was achieved for
most bands. The entire campaign consumed ~1100 orbits, each containing one hour
of serviceable astro-observation. We identified 280 spectral lines from 38
known interstellar molecules (including isotopologues) having intensities in
the range 80 to 0.05 K. An additional 64 weak lines remain unidentified. Apart
from the ground state rotational 1(1,0)--1(0,1) transitions of ortho-H2O, H218O
and H217O, the high energy 6(2,4)--7(1,7) line of para-H2O and the
HDO(2,0,2--1,1,1) line have been observed, as well as the 1,0--0,1 lines from
NH3 and its rare isotopologue 15NH3. We suggest assignments for some
unidentified features, notably the new interstellar molecules ND and SH-.
Severe blends have been detected in the line wings of the H218O, H217O and 13CO
lines changing the true linewidths of the outflow emission.Comment: 21 pages, 10 figures, 7 tables, accepeted for publication in
Astronomy and Astrophysics 30 August 200
A Submillimeter HCN Laser in IRC+10216
We report the detection of a strong submillimeter wavelength HCN laser line
at a frequency near 805 GHz toward the carbon star IRC+10216. This line, the
J=9-8 rotational transition within the (04(0)0) vibrationally excited state, is
one of a series of HCN laser lines that were first detected in the laboratory
in the early days of laser spectroscopy. Since its lower energy level is 4200 K
above the ground state, the laser emission must arise from the inner part of
IRC+10216's circumstellar envelope. To better characterize this environment, we
observed other, thermally emitting, vibrationally excited HCN lines and find
that they, like the laser line, arise in a region of temperature approximately
1000 K that is located within the dust formation radius; this conclusion is
supported by the linewidth of the laser. The (04(0)0), J=9-8 laser might be
chemically pumped and may be the only known laser (or maser) that is excited
both in the laboratory and in space by a similar mechanism.Comment: 11 pages, 3 figure
Discovery of interstellar mercapto radicals (SH) with the GREAT instrument on SOFIA
We report the first detection of interstellar mercapto radicals, obtained
along the sight-line to the submillimeter continuum source W49N. We have used
the GREAT instrument on SOFIA to observe the 1383 GHz Doublet Pi 3/2 J = 5/2 -
3/2 lambda doublet in the upper sideband of the L1 receiver. The resultant
spectrum reveals SH absorption in material local to W49N, as well as in
foreground gas, unassociated with W49N, that is located along the sight-line.
For the foreground material at velocities in the range 37 - 44 km/s with
respect to the local standard of rest, we infer a total SH column density ~ 2.6
E+12 cm-2, corresponding to an abundance of ~ 7 E-9 relative to H2, and
yielding an SH/H2S abundance ratio ~ 0.13. The observed SH/H2S abundance ratio
is much smaller than that predicted by standard models for the production of SH
and H2S in turbulent dissipation regions and shocks, and suggests that the
endothermic neutral-neutral reaction SH + H2 -> H2S + H must be enhanced along
with the ion-neutral reactions believed to produce CH+ and SH+ in diffuse
molecular clouds.Comment: Accepted for publication in Astronomy and Astrophysics (SOFIA/GREAT
special issue
How and When Socially Entrepreneurial Nonprofit Organizations Benefit From Adopting Social Alliance Management Routines to Manage Social Alliances?
Social alliance is defined as the collaboration between for-profit and nonprofit organizations. Building on the insights derived from the resource-based theory, we develop a conceptual framework to explain how socially entrepreneurial nonprofit organizations (SENPOs) can improve their social alliance performance by adopting strategic alliance management routines. We test our framework using the data collected from 203 UK-based SENPOs in the context of cause-related marketing campaign-derived social alliances. Our results confirm a positive relationship between social alliance management routines and social alliance performance. We also find that relational mechanisms, such as mutual trust, relational embeddedness, and relational commitment, mediate the relationship between social alliance management routines and social alliance performance. Moreover, our findings suggest that different types of social alliance motivation can influence the impact of social alliance management routines on different types of the relational mechanisms. In general, we demonstrate that SENPOs can benefit from adopting social alliance management routines and, in addition, highlight how and when the social alliance management routines–social alliance performance relationship might be shaped. Our study offers important academic and managerial implications, and points out future research directions
Radiation damping optical enhancement in cold atoms
This work is licensed under the Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/Open Access journalThe typically tiny effect of radiation damping on a moving body can be amplified to a favorable extent by exploiting the sharp reflectivity slope at one edge of an optically induced stop-band in atoms loaded into an optical lattice. In this paper, this phenomenon is demonstrated for the periodically trapped and coherently driven cold 87Rb atoms, where radiation damping might be much larger than that anticipated in previous proposals and become comparable with radiation pressure. Such an enhancement could be observed even at speeds of only a few meters per second with less than 1.0% absorption, making radiation damping experimentally accessible
Discovery of Large-Scale Gravitational Infall in a Massive Protostellar Cluster
We report Mopra (ATNF), Anglo-Australian Telescope, and Atacama Submillimeter
Telescope Experiment observations of a molecular clump in Carina, BYF73 =
G286.21+0.17, which give evidence of large-scale gravitational infall in the
dense gas. From the millimetre and far-infrared data, the clump has mass ~ 2 x
10^4 Msun, luminosity ~ 2-3 x 10^4 Lsun, and diameter ~ 0.9 pc. From radiative
transfer modelling, we derive a mass infall rate ~ 3.4 x 10^-2 Msun yr-1. If
confirmed, this rate for gravitational infall in a molecular core or clump may
be the highest yet seen. The near-infrared K-band imaging shows an adjacent
compact HII region and IR cluster surrounded by a shell-like photodissociation
region showing H2 emission. At the molecular infall peak, the K imaging also
reveals a deeply embedded group of stars with associated H2 emission. The
combination of these features is very unusual and we suggest they indicate the
ongoing formation of a massive star cluster. We discuss the implications of
these data for competing theories of massive star formation.Comment: v1: 23 pages single-column, 6 figures (some multipart) at end v2: 14
pages 2-column, 6 figures interspersed v3: edited to referee's comments with
new sections and new figures; accepted to MNRAS, 20 pages 2-column, 8 figures
(some multipart) intersperse
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