570 research outputs found
Density functional theory study of Fe(II) adsorption and oxidation on goethite surfaces
We study the interactions between Fe(II) aqua complexes and surfaces of
goethite (alpha-FeOOH) by means of density functional theory calculations
including the so-called Hubbard U correction to the exchange-correlation
functional. Using a thermodynamic approach, we find that (110) and (021)
surfaces in contact with aqueous solutions are almost equally stable, despite
the evident needlelike shape of goethite crystals indicating substantially
different reactivity of the two faces. We thus suggest that crystal anisotropy
may result from different growth rates due to virtually barrierless adsorption
of hydrated ions on the (021) but not on the (110) surface. No clear evidence
is found for spontaneous electron transfer from an adsorbed Fe(II) hex-aqua
complex to a defect-free goethite substrate. Crystal defects are thus inferred
to play an important role in assisting such electron transfer processes
observed in a recent experimental study. Finally, goethite surfaces are
observed to enhance the partial oxidation of adsorbed aqueous Fe(II) upon
reaction with molecular oxygen. We propose that this catalytic oxidation effect
arises from donation of electronic charge from the bulk oxide to the oxidizing
agent through shared hydroxyl ligands anchoring the Fe(II) complexes on the
surface
The Ministry of Passion and Meditation: Robert Southwell\u27s Marie Magdalens Funeral Teares and the Adaptation of Continental Influences
In his most popular prose work, Mary Magdalens Funeral Teares (1591), English Jesuit Robert Southwell adapts the Mary Magdalene tradition by incorporating the meditative practices of St. Ignatius Loyola coupled with the Petrarchan language of poetry. Thus, he creates a prose work that ministered to Catholic souls, appealed to Protestant audiences, and initiated the literature of tears in England. Southwell readapts the traditional image of Mary Magdalene for a Catholic Early Modern audience by utilizing the techniques of Jesuit meditation, which later flourished in the weeper texts of Richard Crashaw and George Herbert. His vividly imagined scenes also employ the Petrarchan and Ovidian language of longing and absence and coincide with both traditional and mystic early church writers such as Bernard and Augustine. Through this combination, Southwell’s Marie Magdalens Funeral Teares resonated with Catholics deprived of both ministry and the presence of Christ in the Eucharist. These contributions solidify Southwell’s place as a pivotal figure in the religious and literary contexts of Early Modern England
Patterns of GPS measured time outdoors after school and objective physical activity in English children: the PEACH project
<p>Abstract</p> <p>Background</p> <p>Observational studies have shown a positive association between time outdoors and physical activity in children. Time outdoors may be a feasible intervention target to increase the physical activity of youth, but methods are required to accurately measure time spent outdoors in a range of locations and over a sustained period. The Global Positioning System (GPS) provides precise location data and can be used to identify when an individual is outdoors. The aim of this study was to investigate whether GPS data recorded outdoors were associated with objectively measured physical activity.</p> <p>Methods</p> <p>Participants were 1010 children (11.0 ± 0.4 years) recruited from 23 urban primary schools in South West England, measured between September 2006 and July 2008. Physical activity was measured by accelerometry (Actigraph GT1M) and children wore a GPS receiver (Garmin Foretrex 201) after school on four weekdays to record time outdoors. Accelerometer and GPS data were recorded at 10 second epochs and were combined to describe patterns of physical activity when both a GPS and accelerometer record were present (outdoors) and when there was accelerometer data only (indoors). ANOVA was used to investigate gender and seasonal differences in the patterns of outdoor and indoor physical activity, and linear regression was used to examine the cross-sectional associations between GPS-measured time outdoors and physical activity.</p> <p>Results</p> <p>GPS-measured time outdoors was a significant independent predictor of children's physical activity after adjustment for potential confounding factors. Physical activity was more than 2.5 fold higher outdoors than indoors (1345.8 ± 907.3 vs 508.9 ± 282.9 counts per minute; F = 783.2, p < .001). Overall, children recorded 41.7 ± 46.1 minutes outdoors between 3.30 pm and 8.30 pm, with more time spent outdoors in the summer months (p < .001). There was no gender difference in time spent outdoors. Physical activity outdoors was higher in the summer than the winter (p < .001), whilst there was no seasonal variation in physical activity indoors.</p> <p>Conclusions</p> <p>Duration of GPS recording is positively associated with objectively measured physical activity and is sensitive to seasonal differences. Minute by minute patterning of GPS and physical activity data is feasible and may be a useful tool to investigate environmental influences on children's physical activity and to identify opportunities for intervention.</p
The 3-dimensional architecture of the Upsilon Andromedae planetary system
The Upsilon Andromedae system is the first exoplanetary system to have the
relative inclination of two planets' orbital planes directly measured, and
therefore offers our first window into the 3-dimensional configurations of
planetary systems. We present, for the first time, full 3-dimensional,
dynamically stable configurations for the 3 planets of the system consistent
with all observational constraints. While the outer 2 planets, c and d, are
inclined by about 30 degrees, the inner planet's orbital plane has not been
detected. We use N-body simulations to search for stable 3-planet
configurations that are consistent with the combined radial velocity and
astrometric solution. We find that only 10 trials out of 1000 are robustly
stable on 100 Myr timescales, or about 8 billion orbits of planet b. Planet b's
orbit must lie near the invariable plane of planets c and d, but can be either
prograde or retrograde. These solutions predict b's mass is in the range 2 - 9
and has an inclination angle from the sky plane of less than 25
degrees. Combined with brightness variations in the combined star/planet light
curve ("phase curve"), our results imply that planet b's radius is about 1.8
, relatively large for a planet of its age. However, the eccentricity
of b in several of our stable solutions reaches values greater than 0.1,
generating upwards of watts in the interior of the planet via tidal
dissipation, possibly inflating the radius to an amount consistent with phase
curve observations.Comment: 17 pages, 10 figures, accepted for publication in ApJ; revised
statement in Section 1.1, references added, results unchange
Archival ethics: The truth of the matter
This essay explores the question of whether records professionals are as aware of the ethical dimensions of their work as they should be. It consider first the historical and professional context of archival ethics, then examines a recent case about business archives involving the author that suggests the need for renewed attention to professional ethics, and concludes with a discussion about how archivists might reconsider the ethical dimensions of their work
Mammals of Nebraska: Checklist, Key, and Bibliography
The Recent mammalian fauna of Nebraska is composed of 89 native species, 8 domestic species that can have feral populations, and 4 wild species introduced by humans, but not by intentional action. Thus, the included checklist and dichotomous key contain 101 species of mammals. Of the native species, 36 are rodents, 20 carnivores, 13 bats, 7 shrews and mole, 7 even-toed ungulates, 4 rabbits and hares, 1 armadillo, and 1 opossum. Another 8 species are identified as potentially occurring in peripheral areas of Nebraska. The bibliography includes 1693 entries that each contain data concerning one or more species of mammals from Nebraska
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The Distance To The Hyades Cluster Based On Hubble Space Telescope Fine Guidance Sensor Parallaxes
Trigonometric parallax observations made with the Hubble Space Telescope (HST) Fine Guidance Sensor (FGS) 3 of seven Hyades members in six fields of view have been analyzed along with their proper motions to determine the distance to the cluster. Knowledge of the convergent point and mean proper motion of the Hyades is critical to the derivation of the distance to the center of the cluster. Depending on the choice of the proper-motion system, the derived cluster center distance varies by 9%. Adopting a reference distance of 46.1 pc or m - M = 3.32, which is derived from the ground-based parallaxes in the General Catalogue of Trigonometric Stellar Parallaxes (1995 edition), the FK5/PPM proper-motion system yields a distance 4% larger, while the Hanson system yields a distance 2% smaller. The HST FGS parallaxes reported here yield either a 14% or 5% larger distance, depending on the choice of the proper-motion system. Orbital parallaxes (Torres et al.) yield an average distance 4% larger than the reference distance. The variation in the distance derived from the HST data illustrates the importance of the proper-motion system and the individual proper motions to the derivation of the distance to the Hyades center; therefore, a full utilization of the HST FGS parallaxes awaits the establishment of an accurate and consistent proper-motion system.NASA HST GTO, HF-1042.01-93A, HF-1046.01-93A, NAS526555Astronom
On religion and cultural policy: notes on the Roman Catholic Church
This paper argues that religious institutions have largely been neglected within the study of cultural policy. This is attributed to the inherently secular tendency of most modern social sciences. Despite the predominance of the ‘secularisation paradigm’, the paper notes that religion continues to promote powerful attachments and denunciations. Arguments between the ‘new atheists’, in particular, Richard Dawkins, and their opponents are discussed, as is Habermas’s conciliatory encounter with Joseph Ratzinger (later Pope Benedict XVI). The paper then moves to a consideration of the Roman Catholic Church as an agent of cultural policy, whose overriding aim is the promotion of ‘Christian consciousness’. Discussion focuses on the contested meanings of this, with reference to (1) the deliberations of Vatican II and (2) the exercise of theological and cultural authority by the Pope and the Congregation for the Doctrine of the Faith (CDF). It is argued that these doctrinal disputes intersect with secular notions of social and cultural policy and warrant attention outside the specialist realm of theological discourse
Affleck-Dine dynamics and the dark sector of pangenesis
Pangenesis is the mechanism for jointly producing the visible and dark matter
asymmetries via Affleck-Dine dynamics in a baryon-symmetric universe. The
baryon-symmetric feature means that the dark asymmetry cancels the visible
baryon asymmetry and thus enforces a tight relationship between the visible and
dark matter number densities. The purpose of this paper is to analyse the
general dynamics of this scenario in more detail and to construct specific
models. After reviewing the simple symmetry structure that underpins all
baryon-symmetric models, we turn to a detailed analysis of the required
Affleck-Dine dynamics. Both gravity-mediated and gauge-mediated supersymmetry
breaking are considered, with the messenger scale left arbitrary in the latter,
and the viable regions of parameter space are determined. In the gauge-mediated
case where gravitinos are light and stable, the regime where they constitute a
small fraction of the dark matter density is identified. We discuss the
formation of Q-balls, and delineate various regimes in the parameter space of
the Affleck-Dine potential with respect to their stability or lifetime and
their decay modes. We outline the regions in which Q-ball formation and decay
is consistent with successful pangenesis. Examples of viable dark sectors are
presented, and constraints are derived from big bang nucleosynthesis, large
scale structure formation and the Bullet cluster. Collider signatures and
implications for direct dark matter detection experiments are briefly
discussed. The following would constitute evidence for pangenesis:
supersymmetry, GeV-scale dark matter mass(es) and a Z' boson with a significant
invisible width into the dark sector.Comment: 51 pages, 7 figures; v2: minor modifications, comments and references
added; v3: minor changes, matches published versio
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