2,862 research outputs found
Do it Right or Not at All: A Longitudinal Evaluation of a Conflict Managment System Implementation
We analyzed an eight-year multi-source longitudinal data set that followed a healthcare system in the Eastern United States as it implemented a major conflict management initiative to encourage line managers to consistently perform Personal Management Interviews (or PMIs) with their employees. PMIs are interviews held between two individuals, designed to prevent or quickly resolve interpersonal problems before they escalate to formal grievances. This initiative provided us a unique opportunity to empirically test key predictions of Integrated Conflict Management System (or ICMS) theory. Analyzing survey and personnel file data from 5,449 individuals from 2003 to 2010, we found that employees whose managers provided high-quality interviews perceived significantly higher participative work climates and had lower turnover rates. However, retention was worse when managers provided poor-quality interviews than when they conducted no interviews at all. Together these findings highlight the critical role that line mangers play in the success of conflict management systems
Gas Giant Protoplanets Formed by Disk Instability in Binary Star Systems
We present a suite of three dimensional radiative gravitational hydrodynamics
models suggesting that binary stars may be quite capable of forming planetary
systems similar to our own. The new models with binary companions do not employ
any explicit artificial viscosity, and also include the third (vertical)
dimension in the hydrodynamic calculations, allowing for transient phases of
convective cooling. The calculations of the evolution of initially marginally
gravitationally stable disks show that the presence of a binary star companion
may actually help to trigger the formation of dense clumps that could become
giant planets. We also show that in models without binary companions, which
begin their evolution as gravitationally stable disks, the disks evolve to form
dense rings, which then break-up into self-gravitating clumps. These latter
models suggest that the evolution of any self-gravitating disk with sufficient
mass to form gas giant planets is likely to lead to a period of disk
instability, even in the absence of a trigger such as a binary star companion.Comment: 52 pages, 28 figure
Phase noise measurements of the 400-kW, 2.115-GHz (S-band) transmitter
The measurement theory is described and a test method to perform phase noise verification using off-the-shelf components and instruments is presented. The measurement technique described consists of a double-balanced mixer used as phase detector, followed by a low noise amplifier. An FFT spectrum analyzer is then used to view the modulation components. A simple calibration procedure is outlined that ensures accurate measurements. A block diagram of the configuration is presented as well as actual phase noise data from the 400 kW, 2.115 GHz (S-band) klystron transmitter
On The Effect of Giant Planets on the Scattering of Parent Bodies of Iron Meteorite from the Terrestrial Planet Region into the Asteroid Belt: A Concept Study
In their model for the origin of the parent bodies of iron meteorites, Bottke
et al proposed differentiated planetesimals that were formed in the region of
1-2 AU during the first 1.5 Myr, as the parent bodies, and suggested that these
objects and their fragments were scattered into the asteroid belt as a result
of interactions with planetary embryos. Although viable, this model does not
include the effect of a giant planet that might have existed or been growing in
the outer regions. We present the results of a concept study where we have
examined the effect of a planetary body in the orbit of Jupiter on the early
scattering of planetesimals from terrestrial region into the asteroid belt. We
integrated the orbits of a large battery of planetesimals in a disk of
planetary embryos, and studied their evolutions for different values of the
mass of the planet. Results indicate that when the mass of the planet is
smaller than 10 Earth-masses, its effects on the interactions among
planetesimals and planetary embryos is negligible. However, when the planet
mass is between 10 and 50 Earth-masses, simulations point to a transitional
regime with ~50 Earth-mass being the value for which the perturbing effect of
the planet can no longer be ignored. Simulations also show that further
increase of the mass of the planet strongly reduces the efficiency of the
scattering of planetesimals from the terrestrial planet region into the
asteroid belt. We present the results of our simulations and discuss their
possible implications for the time of giant planet formation.Comment: 20 pages, 7 figures, accepted for publication in Ap
Migration of giant planets in planetesimal discs
Planets orbiting a planetesimal circumstellar disc can migrate inward from
their initial positions because of dynamical friction between planets and
planetesimals. The migration rate depends on the disc mass and on its time
evolution. Planets that are embedded in long-lived planetesimal discs, having
total mass of , can migrate inward a large distance and
can survive only if the inner disc is truncated or because of tidal interaction
with the star. In this case the semi-major axis, a, of the planetary orbit is
less than 0.1 AU. Orbits with larger are obtained for smaller value of the
disc mass or for a rapid evolution (depletion) of the disc. This model may
explain several of the orbital features of the giant planets that were
discovered in last years orbiting nearby stars as well as the metallicity
enhancement found in several stars associated with short-period planets.Comment: 21 pages; 6 encapsulated figures. Accepted by MNRA
Secretly Eccentric: The Giant Planet and Activity Cycle of GJ 328
We announce the discovery of a ~2 Jupiter-mass planet in an eccentric 11-year
orbit around the K7/M0 dwarf GJ 328. Our result is based on 10 years' worth of
radial velocity (RV) data from the Hobby-Eberly and Harlan J. Smith telescopes
at McDonald Observatory, and from the Keck Telescope at Mauna Kea. Our analysis
of GJ 328's magnetic activity via the Na I D features reveals a long-period
stellar activity cycle, which creates an additional signal in the star's RV
curve with amplitude 6-10 m/s. After correcting for this stellar RV
contribution, we see that the orbit of the planet is more eccentric than
suggested by the raw RV data. GJ 328b is currently the most massive,
longest-period planet discovered around a low-mass dwarf.Comment: Accepted for publication in Ap
The Supernova Triggered Formation and Enrichment of Our Solar System
We investigate the enrichment of the pre-solar cloud core with short lived
radionuclides (SLRs), especially 26Al. The homogeneity and the surprisingly
small spread in the ratio 26Al/27Al observed in the overwhelming majority of
calcium-aluminium-rich inclusions (CAIs) in a vast variety of primitive
chondritic meteorites places strong constraints on the formation of the the
solar system. Freshly synthesized radioactive 26Al has to be included and well
mixed within 20kyr. After discussing various scenarios including X-winds, AGB
stars and Wolf-Rayet stars, we come to the conclusion that triggering the
collapse of a cold cloud core by a nearby supernova is the most promising
scenario. We then narrow down the vast parameter space by considering the
pre-explosion survivability of such a clump as well as the cross-section
necessary for sufficient enrichment. We employ numerical simulations to address
the mixing of the radioactively enriched SN gas with the pre-existing gas and
the forced collapse within 20kyr. We show that a cold clump of 10Msun at a
distance of 5pc can be sufficiently enriched in 26Al and triggered into
collapse fast enough - within 18kyr after encountering the supernova shock -
for a range of different metallicities and progenitor masses, even if the
enriched material is assumed to be distributed homogeneously in the entire
supernova bubble. In summary, we envision an environment for the birth place of
the Solar System 4.567Gyr ago similar to the situation of the pillars in M16
nowadays, where molecular cloud cores adjacent to an HII region will be hit by
a supernova explosion in the future. We show that the triggered collapse and
formation of the Solar System as well as the required enrichment with
radioactive 26Al are possible in this scenario.Comment: 12 pages, 8 figures, accepted for publication in ApJ. Resolution of
most figures degraded to fit within arXiv size limits. A full resolution
version is available at
http://www.usm.uni-muenchen.de/~gritschm/Gritschneder_2011_sun.pd
Dynamical Stability and Habitability of Gamma Cephei Binary-Planetary System
It has been suggested that the long-lived residual radial velocity variations
observed in the precision radial velocity measurements of the primary of Gamma
Cephei (HR8974, HD222404, HIP116727) are likely due to a Jupiter-like planet
around this star (Hatzes et al, 2003). In this paper, the orbital dynamics of
this plant is studied and also the possibility of the existence of a
hypothetical Earth-like planet in the habitable zone of its central star is
discussed. Simulations, which have been carried out for different values of the
eccentricity and semimajor axis of the binary, as well as the orbital
inclination of its Jupiter-like planet, expand on previous studies of this
system and indicate that, for the values of the binary eccentricity smaller
than 0.5, and for all values of the orbital inclination of the Jupiter-like
planet ranging from 0 to 40 degrees, the orbit of this planet is stable. For
larger values of the binary eccentricity, the system becomes gradually
unstable. Integrations also indicate that, within this range of orbital
parameters, a hypothetical Earth-like planet can have a long-term stable orbit
only at distances of 0.3 to 0.8 AU from the primary star. The habitable zone of
the primary, at a range of approximately 3.1 to 3.8 AU, is, however, unstable.Comment: 25 pages, 7 figures, 3 tables, submitted for publicatio
Spurious harmonic response of multipulse quantum sensing sequences
Multipulse sequences based on Carr-Purcell decoupling are frequently used for
narrow-band signal detection in single spin magnetometry. We have analyzed the
behavior of multipulse sensing sequences under real-world conditions, including
finite pulse durations and the presence of detunings. We find that these
non-idealities introduce harmonics to the filter function, allowing additional
frequencies to pass the filter. In particular, we find that the XY family of
sequences can generate signals at the 2fac, 4fac and 8fac harmonics and their
odd subharmonics, where fac is the ac signal frequency. Consideration of the
harmonic response is especially important for diamond-based nuclear spin
sensing where the NMR frequency is used to identify the nuclear spin species,
as it leads to ambiguities when several isotopes are present.Comment: 6 pages, 7 figure
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