833 research outputs found
A Quantitative Study Examining How Training Enhances Policy Compliance
For decades, the Department of Defense has been plagued by persistent cost, schedule, and performance problems in defense acquisition programs. Recent changes in Department of Defense acquisition policy were intended to improve efficiency and are demonstrating some improvement in terms of overall cost improvements, yet little is understood about whether training efforts related to the new policies are producing policy-compliant behavior on the job. Using Edgar Schein\u27s \u27Onion Model\u27 of organizational change as the theoretical construct, the purpose of this study was to examine through an ex post facto, cross-sectional longitudinal study whether there is a significant relationship between learning achieved from Defense Acquisition University (DAU) training in acquisition policy and application of learned policy-compliant behavior, as represented by the variables learning achieved and applied training. Data were obtained from DAU that spanned 19 months and over 334,000 training events separated into 40 course-type subgroups. These data were analyzed through hierarchical regression analysis to test whether concepts learned in policy training predicted policy compliance. The findings confirmed that the independent variable of \u27learning achieved\u27 is predictive of policy compliance
The host of the Type I SLSN 2017egm: A young, sub-solar metallicity environment in a massive spiral galaxy
Here we present an integral-field study of the massive, high-metallicity
spiral NGC 3191, the host of SN 2017egm, the closest SLSN Type I to date. We
use data from PMAS/CAHA and the public MaNGA survey to shed light on the
properties of the SLSN site and the origin of star-formation in this
non-starburst spiral galaxy. We map the physical properties different
\ion{H}{II} regions throughout the galaxy and characterize their stellar
populations using the STARLIGHT fitting code. Kinematical information allows to
study a possible interaction with its neighbouring galaxy as the origin of
recent star formation activity which could have caused the SLSN. NGC 3191 shows
intense star-formation in the western part with three large SF regions of low
metallicity. The central regions of the host have a higher metallicity, lower
specific star-formation rate and lower ionization. Modeling the stellar
populations gives a different picture: The SLSN region has two dominant stellar
populations with different ages, the youngest one with an age of 2-10 Myr and
lower metallicity, likely the population from which the SN progenitor
originated. Emission line kinematics of NGC 3191 show indications of
interaction with its neighbour MCG+08-19-017 at 45 kpc, which might be
responsible for the recent starburst. In fact, this galaxy pair has in total
hosted 4 SNe, 1988B (Type Ia), SN 2003ds (Type Ic in MCG+08-19-017), PTF10bgl
(SLSN-Type II) and 2017egm, underlying the enhanced SF in both galaxies due to
interaction. Our study shows that one has to be careful interpreting global
host and even gas properties without looking at the stellar population history
of the region. SLSNe seem to still be consistent with massive stars ( 20
M) requiring low () metallicity and those environments
can also occur in massive, late-type galaxies but not necessarily starbursts.Comment: Accepted for publication in A&A, 13 pages, 11 figures, 7 tables.
Abstract has been reduced to match arXiv form requirement
The interstellar C18O/C17O ratio in the solar neighbourhood: The rho Oph cloud
Observations of up to ten carbon monoxide (CO and isotopomers) transitions
are presented to study the interstellar C18O/C17O ratio towards 21 positions in
the nearby (d~140pc) low-mass star forming cloud rho Oph. A map of the C18O
J=1-0 distribution of parts of the cloud is also shown. An average
12C18O/12C17O isotopomeric ratio of 4.11 +/- 0.14, reflecting the 18O/17O
isotope ratio, is derived from Large Velocity Gradient (LVG) calculations. From
LTE column densities we derive a ratio of 4.17 +/-0.26. These calculations also
show that the kinetic temperature decreases from about 30 K in the cloud
envelope to about 10 K in the cloud cores. This decrease is accompanied by an
increase of the average molecular hydrogen density from 10^4 cm-3 to >10^5
cm-3. Towards some lines of sight C18O optical depths reach values of order
unity.Comment: 13 pages, 9 figures; accepted for publication in A&
The Photon Dominated Region in the IC 348 molecular cloud
In this paper we discuss the physical conditions of clumpy nature in the IC
348 molecular cloud.
We combine new observations of fully sampled maps in [C I] at 492 GHz and
12CO 4--3, taken with the KOSMA 3 m telescope at about 1' resolution, with
FCRAO data of 12CO 1--0, 13CO 1--0 and far-infrared continuum data observed by
HIRES/IRAS. To derive the physical parameters of the region we analyze the
three different line ratios. A first rough estimate of abundance is obtained
from an LTE analysis. To understand the [C I] and CO emission from the PDRs in
IC 348, we use a clumpy PDR model. With an ensemble of identical clumps, we
constrain the total mass from the observed absolute intensities. Then we apply
a more realistic clump distribution model with a power law index of 1.8 for
clump-mass spectrum and a power law index of 2.3 for mass-size relation.
We provide detailed fits to observations at seven representative positions in
the cloud, revealing clump densities between 4 10 cm and 4
10 cm and C/CO column density ratios between 0.02 and 0.26. The
derived FUV flux from the model fit is consistent with the field calculated
from FIR continuum data, varying between 2 and 100 Draine units across the
cloud. We find that both an ensemble of identical clumps and an ensemble with a
power law clump mass distribution produce line intensities which are in good
agreement (within a factor ~ 2) with the observed intensities. The models
confirm the anti-correlation between the C/CO abundance ratio and the hydrogen
column density found in many regions.Comment: 11 pages, 8 figures, accepted by A&
A method for reconstructing the variance of a 3D physical field from 2D observations: Application to turbulence in the ISM
We introduce and test an expression for calculating the variance of a
physical field in three dimensions using only information contained in the
two-dimensional projection of the field. The method is general but assumes
statistical isotropy. To test the method we apply it to numerical simulations
of hydrodynamic and magnetohydrodynamic turbulence in molecular clouds, and
demonstrate that it can recover the 3D normalised density variance with ~10%
accuracy if the assumption of isotropy is valid. We show that the assumption of
isotropy breaks down at low sonic Mach number if the turbulence is
sub-Alfvenic. Theoretical predictions suggest that the 3D density variance
should increase proportionally to the square of the Mach number of the
turbulence. Application of our method will allow this prediction to be tested
observationally and therefore constrain a large body of analytic models of star
formation that rely on it.Comment: 8 pages, 9 figures, accepted for publication in MNRA
CuCoS Deposited on TiO: Controlling the pH Value Boosts Photocatalytic Hydrogen Evolution
Metallic spinel-type CuCoS nanoparticles were deposited on nanocrystalline TiO (P25®), forming heterostructure nanocomposites. The nanocomposites were characterized in detail by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), nitrogen sorption (BET) and UV/Vis spectroscopy. Variation of the CuCoS:TiO ratio to an optimum value generated a catalyst which shows a very high photocatalytic H production rate at neutral pH of 32.3 µmol/h (0.72 mLh), which is much larger than for pure TiO (traces of H). The catalyst exhibits an extraordinary long-term stability and after 70 h irradiation time about 2 mmol H were generated. An increased light absorption and an efficient charge separation for the sample with the optimal CuCoS:TiO ratio is most probably responsible for the high catalytic activity
A map of OMC-1 in CO 9-8
The distribution of 12C16O J=9-8 (1.037 THz) emission has been mapped in
OMC-1 at 35 points with 84" resolution. This is the first map of this source in
this transition and only the second velocity-resolved ground-based observation
of a line in the terahertz frequency band. There is emission present at all
points in the map, a region roughly 4' by 6' in size, with peak antenna
temperature dropping only near the edges. Away from the Orion KL outflow, the
velocity structure suggests that most of the emission comes from the OMC-1
photon-dominated region, with a typical linewidthof 3-6 km/s. Large velocity
gradient modeling of the emission in J=9-8 and six lower transitions suggests
that the lines originate in regions with temperatures around 120 K and
densities of at least 10^(3.5) cm^(-3) near theta^(1) C Ori and at the Orion
Bar, and from 70 K gas at around 10^(4) cm^(-3) southeast and west of the bar.
These observations are among the first made with the 0.8 m Smithsonian
Astrophysical Observatory Receiver Lab Telescope, a new instrument designed to
observe at frequencies above 1 THz from an extremely high and dry site in
northern Chile.Comment: Minor changes to references, text to match ApJ versio
Nuclear spin diffusion in the semiconductor TlTaS3
We report on a 203Tl and 205Tl nuclear magnetic resonance study of the chain
ternary semiconductor TlTaS3. We show that spin-lattice relaxation in this
compound is driven by two contributions, namely by interactions of nuclear
spins with thermally activated carriers and with localized electron spins. The
latter mechanism dominates at lower temperature; at that, our measurements
provide striking manifestation of the spin-diffusion-limited relaxation regime.
The experimental data obtained allow us to estimate the spin diffusion
coefficient.Comment: 15 pages, 5 figure
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