5,043 research outputs found
Hearers of the Word : Luke\u27s Gospel as Sacramental Formation for a Liturgical Community
(Excerpt)
It is privilege to return to the Institute of Liturgical Studies after a long absence, especially on a subject that has consumed me in one way or another over the last fifteen years. I am very grateful to the advisory council for assigning me a topic that develops the biblical foundations of the catechumenate. My doctoral work on Emmaus, my vocation as professor of exegesis and pastoral theology, my participation in the ELCA and LCMS working groups on the catechumenate, as well as my participation in the Missouri Synod\u27s efforts to develop its own catechumenal process, have all contributed to my remarks this afternoon. But it is through conversations with colleagues about the New Testament as a catechetical document, and particularly my work on Luke\u27s gospel, that has been seminal to my own thinking about the biblical foundations for the catechumenate
Roche volume filling and the dissolution of open star clusters
From direct N-body simulations we find that the dynamical evolution of star
clusters is strongly influenced by the Roche volume filling factor. We present
a parameter study of the dissolution of open star clusters with different Roche
volume filling factors and different particle numbers. We study both Roche
volume underfilling and overfilling models and compare with the Roche volume
filling case. We find that in the Roche volume overfilling limit of our
simulations two-body relaxation is no longer the dominant dissolution mechanism
but the changing cluster potential. We call this mechnism "mass-loss driven
dissolution" in contrast to "two-body relaxation driven dissolution" which
occurs in the Roche volume underfilling regime. We have measured scaling
exponents of the dissolution time with the two-body relaxation time. In this
experimental study we find a decreasing scaling exponent with increasing Roche
volume filling factor. The evolution of the escaper number in the Roche volume
overfilling limit can be described by a log-logistic differential equation. We
report the finding of a resonance condition which may play a role for the
evolution of star clusters and may be calibrated by the main periodic orbit in
the large island of retrograde quasiperiodic orbits in the Poincar\'e surfaces
of section. We also report on the existence of a stability curve which may be
of relevance with respect to the structure of star clusters.Comment: 14 pages, 10+1 figures, accepted by Astronomische Nachrichte
Why farmers sometimes love risks: evidence from India
Using a unique data set collected among farmers in India’s semiarid tropics, we document the surprising prevalence of risk-taking behavior in the face of realistically framed high-stakes gambles. We hypothesize that this apparently anomalous behavior is due to a combination of credit constraints and nonconvexities in production. In particular, the high-stakes nature of the gambles creates the potential for a farmer to undertake a productive investment that would normally be unaffordable and thereby move to a permanently higher level of income. We show that the degree to which farmers are willing to accept risk in return for this opportunity appears to relate in an intuitive way to their current agricultural production technology as well as the demographic composition of their household
Pests and Agricultural Production under Climate Change
Although the effect of climate change on agricultural pests has been studied by biologists, thus far, large-scale assessments of climate change and agriculture have not included the impact of pests. We develop a simple theoretical model of farmer-pest interaction under climate change and explore the potential impacts on land values.Environmental Economics and Policy,
The star cluster survivability after gas expulsion is independent of the impact of the Galactic tidal field
We study the impact of the tidal field on the survivability of star clusters
following instantaneous gas expulsion. Our model clusters are formed with a
centrally-peaked star-formation efficiency profile as a result of
star-formation taking place with a constant efficiency per free-fall time. We
define the impact of the tidal field as the ratio of the cluster half-mass
radius to its Jacobi radius immediately after gas expulsion, . We vary by varying either the Galactocentric distance,
or the size (hence volume density) of star clusters.
We propose a new method to measure the violent relaxation duration, in which
we compare the total mass-loss rate of star clusters with their stellar
evolutionary mass-loss rate. That way, we can robustly estimate the bound mass
fraction of our model clusters at the end of violent relaxation. The duration
of violent relaxation correlates linearly with the Jacobi radius, when
considering identical clusters at different Galactocentric distances. In
contrast, it is nearly constant for the solar neighbourhood clusters, slightly
decreasing with . The violent relaxation does not last longer than 50
Myr in our simulations.
Identical model clusters placed at different Galactocentric distances have
the same final bound fraction, despite experiencing different impacts of the
tidal field. The solar neighbourhood clusters with different densities
experience only limited variations of their final bound fraction.
In general, we conclude that the cluster survivability after instantaneous
gas expulsion, as measured by their bound mass fraction at the end of violent
relaxation, , is independent of the impact of the tidal field,
.Comment: accepted for publication in MNRAS, 8 pages, 5 figures,3 table
Coexisting patterns of population oscillations: the degenerate Neimark Sacker bifurcation as a generic mechanism
We investigate a population dynamics model that exhibits a Neimark Sacker
bifurcation with a period that is naturally close to 4. Beyond the bifurcation,
the period becomes soon locked at 4 due to a strong resonance, and a second
attractor of period 2 emerges, which coexists with the first attractor over a
considerable parameter range. A linear stability analysis and a numerical
investigation of the second attractor reveal that the bifurcations producing
the second attractor occur naturally in this type of system.Comment: 8 pages, 3 figure
Effects of galaxy--satellite interactions on bar formation
Aims. We aim to show how encounters with low-mass satellite galaxies may
alter the bar formation in a Milky Way-like disc galaxy. Methods. We use
high-resolution N-body simulations of a disc galaxy prone to mild bar
instability. For realistic initial conditions of satellites, we take advantage
of cosmological simulations of Milky Way-like dark matter haloes. Results. The
satellites may have a significant impact on the time of bar formation. Some
runs with satellites demonstrate a delay, while others show an advancement in
bar formation compared to the isolated run, with such time differences reaching
1 Gyr. Meanwhile, the final bar configuration, including its very
appearance and the bar characteristics such as the pattern speed and the
exponential growth rate of its amplitude are independent of the number of
encounters and their orbits. The contribution of satellites with masses below
is insignificant, unless their pericentre distances are small.
We suggest that the encounters act indirectly via inducing perturbations across
the disc that evolve to delayed waves in the central part and interfere with an
emerging seed bar. The predicted effect for the present-day host galaxy is
expected to be even more significant at redshifts .Comment: 16 pages, 14 figures and 4 table
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