89 research outputs found
Moving on from the software engineers' gambit: an approach to support the defense of software effort estimates
Pressure for higher productivity and faster delivery is increasingly
pervading software organizations. This can lead software engineers to act like
chess players playing a gambit -- making sacrifices of their technically sound
estimates, thus submitting their teams to time pressure. In turn, time pressure
can have varied detrimental effects, such as poor product quality and emotional
distress, decreasing productivity, which leads to more time pressure and
delays: a hard-to-stop vicious cycle. This reveals a need for moving on from
the more passive strategy of yielding to pressure to a more active one of
defending software estimates. Therefore, we propose an approach to support
software estimators in acquiring knowledge on how to carry out such defense, by
introducing negotiation principles encapsulated in a set of defense lenses,
presented through a digital simulation. We evaluated the proposed approach
through a controlled experiment with software practitioners from different
companies. We collected data on participants' attitudes, subjective norms,
perceived behavioral control, and intentions to perform the defense of their
estimates in light of the Theory of Planned Behavior. We employed a frequentist
and a bayesian approach to data analysis. Results show improved scores among
experimental group participants after engaging with the digital simulation and
learning about the lenses. They were also more inclined to choose a defense
action when facing pressure scenarios than a control group exposed to questions
to reflect on the reasons and outcomes of pressure over estimates. Qualitative
evidence reveals that practitioners perceived the set of lenses as useful in
their current work environments. Collectively, these results show the
effectiveness of the proposed approach and its perceived relevance for the
industry, despite the low amount of time required to engage with it.Comment: 12 pages, 3 figure
The defect variance of random spherical harmonics
The defect of a function is defined as the
difference between the measure of the positive and negative regions. In this
paper, we begin the analysis of the distribution of defect of random Gaussian
spherical harmonics. By an easy argument, the defect is non-trivial only for
even degree and the expected value always vanishes. Our principal result is
obtaining the asymptotic shape of the defect variance, in the high frequency
limit. As other geometric functionals of random eigenfunctions, the defect may
be used as a tool to probe the statistical properties of spherical random
fields, a topic of great interest for modern Cosmological data analysis.Comment: 19 page
Organic matter composition and greenhouse gas production of thawing subsea permafrost in the Laptev Sea
Subsea permafrost represents a large carbon pool that might be or become a significant greenhouse gas source. Scarcity of observational data causes large uncertainties. We here use five 21-56 m long subsea permafrost cores from the Laptev Sea to constrain organic carbon (OC) storage and sources, degradation state and potential greenhouse gas production upon thaw. Grain sizes, optically-stimulated luminescence and biomarkers suggest deposition of aeolian silt and fluvial sand over 160 000 years, with dominant fluvial/alluvial deposition of forest- and tundra-derived organic matter. We estimate an annual thaw rate of 1.3 ± 0.6 kg OC m−2 in subsea permafrost in the area, nine-fold exceeding organic carbon thaw rates for terrestrial permafrost. During 20-month incubations, CH4 and CO2 production averaged 1.7 nmol and 2.4 µmol g−1 OC d−1, providing a baseline to assess the contribution of subsea permafrost to the high CH4 fluxes and strong ocean acidification observed in the region
A Planetary Microlensing Event with an Unusually Red Source Star: MOA-2011-BLG-291
We present the analysis of planetary microlensing event MOA-2011-BLG-291,
which has a mass ratio of and a source star that
is redder (or brighter) than the bulge main sequence. This event is located at
a low Galactic latitude in the survey area that is currently planned for NASA's
WFIRST exoplanet microlensing survey. This unusual color for a microlensed
source star implies that we cannot assume that the source star is in the
Galactic bulge. The favored interpretation is that the source star is a lower
main sequence star at a distance of kpc in the Galactic disk.
However, the source could also be a turn-off star on the far side of the bulge
or a sub-giant in the far side of the Galactic disk if it experiences
significantly more reddening than the bulge red clump stars. However, these
possibilities have only a small effect on our mass estimates for the host star
and planet. We find host star and planet masses of and from a Bayesian
analysis with a standard Galactic model under the assumption that the planet
hosting probability does not depend on the host mass or distance. However, if
we attempt to measure the host and planet masses with host star brightness
measurements from high angular resolution follow-up imaging, the implied masses
will be sensitive to the host star distance. The WFIRST exoplanet microlensing
survey is expected to use this method to determine the masses for many of the
planetary systems that it discovers, so this issue has important design
implications for the WFIRST exoplanet microlensing survey
Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb
We report the discovery of the microlensing planet OGLE-2018-BLG-0740Lb. The
planet is detected with a very strong signal of , but
the interpretation of the signal suffers from two types of degeneracies. One
type is caused by the previously known close/wide degeneracy, and the other is
caused by an ambiguity between two solutions, in which one solution requires to
incorporate finite-source effects, while the other solution is consistent with
a point-source interpretation. Although difficult to be firmly resolved based
on only the photometric data, the degeneracy is resolved in strong favor of the
point-source solution with the additional external information obtained from
astrometric and spectroscopic observations. The small astrometric offset
between the source and baseline object supports that the blend is the lens and
this interpretation is further secured by the consistency of the spectroscopic
distance estimate of the blend with the lensing parameters of the point-source
solution. The estimated mass of the host is and the mass
of the planet is (close solution) or (wide solution) and the lens is located at a distance of ~kpc.
The bright nature of the lens, with (), combined with
its dominance of the observed flux suggest that radial-velocity (RV) follow-up
observations of the lens can be done using high-resolution spectrometers
mounted on large telescopes, e.g., VLT/ESPRESSO, and this can potentially not
only measure the period and eccentricity of the planet but also probe for
close-in planets. We estimate that the expected RV amplitude would be .Comment: 12 pages, 11 figures, 4 table
Candidate Brown-dwarf Microlensing Events with Very Short Timescales and Small Angular Einstein Radii
Short-timescale microlensing events are likely to be produced by substellar brown dwarfs (BDs), but it is difficult to securely identify BD lenses based on only event timescales t_E because short-timescale events can also be produced by stellar lenses with high relative lens-source proper motions. In this paper, we report three strong candidate BD-lens events found from the search for lensing events not only with short timescales (t_E ≲ 6 days) but also with very small angular Einstein radii (θ_E ≲ 0.05 mas) among the events that have been found in the 2016–2019 observing seasons. These events include MOA-2017-BLG-147, MOA-2017-BLG-241, and MOA-2019-BLG-256, in which the first two events are produced by single lenses and the last event is produced by a binary lens. From the Monte Carlo simulations of Galactic events conducted with the combined t_E and θ_E constraint, it is estimated that the lens masses of the individual events are
0.051^(+0.100)_(−0.027) M⊙, 0.044^(+0.090)_(−0.023) M⊙, and 0.046^(+0.067)_(−0.023) M⊙/0.038^(+0.056)_(−0.019) M⊙ and the probability of the lens mass smaller than the lower limit of stars is ~80% for all events. We point out that routine lens mass measurements of short-timescale lensing events require survey-mode space-based observations
OGLE-2018-BLG-0022: First Prediction of an Astrometric Microlensing Signal from a Photometric Microlensing Event
In this work, we present the analysis of the binary microlensing event
OGLE-2018-BLG-0022 that is detected toward the Galactic bulge field. The dense
and continuous coverage with the high-quality photometry data from ground-based
observations combined with the space-based {\it Spitzer} observations of this
long time-scale event enables us to uniquely determine the masses and of the individual lens components.
Because the lens-source relative parallax and the vector lens-source relative
proper motion are unambiguously determined, we can likewise unambiguously
predict the astrometric offset between the light centroid of the magnified
images (as observed by the {\it Gaia} satellite) and the true position of the
source. This prediction can be tested when the individual-epoch {\it Gaia}
astrometric measurements are released.Comment: 10 pages, 10 figures, 4 table
Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M-dwarf
We report the discovery of a microlensing planet
OGLE-2018-BLG-0596Lb, with preferred planet-host mass ratio . The planetary signal, which is characterized by a short "bump" on the rising side of the lensing light curve, was densely
covered by ground-based surveys. We find that the signal can be explained by a
bright source that fully envelops the planetary caustic, i.e., a "Hollywood"
geometry. Combined with the source proper motion measured from , the
satellite parallax measurement makes it possible to precisely
constrain the lens physical parameters. The preferred solution, in which the
planet perturbs the minor image due to lensing by the host, yields a
Uranus-mass planet with a mass of orbiting
a mid M-dwarf with a mass of . There is also
a second possible solution that is substantially disfavored but cannot be ruled
out, for which the planet perturbs the major image. The latter solution yields
and . By
combining the microlensing and data together with a Galactic model, we
find in either case that the lens lies on the near side of the Galactic bulge
at a distance . Future adaptive optics
observations may decisively resolve the major image/minor image degeneracy.Comment: 34 pages, 8 figures, Submitted to AAS journa
A Gas Giant Planet in the OGLE-2006-BLG-284L Stellar Binary System
We present the analysis of microlensing event OGLE-2006-BLG-284, which has a
lens system that consists of two stars and a gas giant planet with a mass ratio
of to the primary. The mass ratio of the
two stars is , and their projected separation is AU, while the projected separation of the planet from the primary
is AU. For this lens system to have stable orbits, the
three-dimensional separation of either the primary and secondary stars or the
planet and primary star must be much larger than that these projected
separations. Since we do not know which is the case, the system could include
either a circumbinary or a circumstellar planet. Because there is no
measurement of the microlensing parallax effect or lens system brightness, we
can only make a rough Bayesian estimate of the lens system masses and
brightness. We find host star and planet masses of , , and
, and the -band magnitude of the combined
brightness of the host stars is . The separation
between the lens and source system will be mas in mid-2020, so it
should be possible to detect the host system with follow-up adaptive optics or
Hubble Space Telescope observations
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