8,292 research outputs found
The journey of decision making in the Word-directed Christian churches
https://place.asburyseminary.edu/ecommonsatsdissertations/1379/thumbnail.jp
Geology, petrology and origin of the Precambrian igneous rocks located in the area north of Boston
Geology of the coastal lowlands, Boston to Kennebunk, Maine: The 76th annual meeting New England Intercollegiate Geological Conference, Danvers, Massachusetts, October 12-14, 1984: Trip C-
Modeling the light curve of the transient SCP06F6
We consider simple models based on core collapse or pair-formation supernovae
to account for the light curve of the transient SCP06F6. A radioactive decay
diffusion model provides estimates of the mass of the required radioactive
nickel and the ejecta as functions of the unknown redshift. An opacity change
such as by dust formation or a recombination front may account for the rapid
decline from maximum. We particularly investigate two specific redshifts:
, for which Gaensicke et al. (2008) have proposed that the
unidentified broad absorption features in the spectrum of SCP06F6 are C
Swan bands, and based on a crude agreement with the Ca H&K and UV
iron-peak absorption features that are characteristic of supernovae of various
types. The ejected masses and kinetic energies are smaller for a more tightly
constrained model invoking envelope recombination. We also discuss the
possibilities of circumstellar matter (CSM) shell diffusion and shock
interaction models. In general, optically-thick CSM diffusion models can fit
the data with the underlying energy coming from an energetic buried supernova.
Models in which the CSM is of lower density so that the shock energy is both
rapidly thermalized and radiated tend not to be self-consistent. We suggest
that a model of SCP06F6 worth futher exploration is one in which the redshift
is 0.57, the spectral features are Ca and iron peak elements, and the
light curve is powered by the diffusive release of a substantial amount of
energy from nickel decay or from an energetic supernova buried in the ejecta of
an LBV-like event.Comment: 27 pages, 6 figure
Generalized Semi-Analytical Models of Supernova Light Curves
We present generalized supernova (SN) light curve (LC) models for a variety
of power inputs. We provide an expression for the power input that is produced
by self-similar forward and reverse shocks in SN ejecta - circumstellar matter
(CSM) interaction. We find that this ejecta-CSM interaction luminosity is in
agreement with results from multi-dimensional radiation hydrodynamics
simulations in the optically-thin case. We develop a model for the case of an
optically-thick CSM by invoking an approximation for the effects of radiative
diffusion. In the context of this model, we provide predictions for the time of
forward shock break-out from the optically-thick part of the CSM envelope. We
also introduce a hybrid LC model that incorporates ejecta-CSM interaction plus
Ni-56 and Co-56 radioactive decay input. We fit this hybrid model to the LC of
the Super-Luminous Supernova (SLSN) 2006gy. We find that this model provides a
better fit to the LC of this event than previously presented models. We also
address the relation between Type IIL and Type IIn SN with ejecta-CSM
interaction models. Forward and reverse shock power input due to CSM
interaction can produce the LCs of Type IIn SNe in terms of duration, shape and
decline rate. This model can also produce LCs that are symmetric in shape
around peak luminosity. We conclude that the observed LC variety of SNe Type
IIn and of the SLSNe is likely to be a byproduct of the large range of
conditions relevant to significant ejecta-CSM interaction as a power source.Comment: 48 pages, 13 figure
Effective risk governance for environmental policy making: a knowledge management perspective
Effective risk management within environmental policy making requires knowledge on natural, economic and social systems to be integrated; knowledge characterised by complexity, uncertainty and ambiguity. We describe a case study in a (UK) central government department exploring how risk governance supports and hinders this challenging integration of knowledge. Forty-five semi-structured interviews were completed over a two year period. We found that lateral knowledge transfer between teams working on different policy areas was widely viewed as a key source of knowledge. However, the process of lateral knowledge transfer was predominantly informal and unsupported by risk governance structures. We argue this made decision quality vulnerable to a loss of knowledge through staff turnover, and time and resource pressures. Our conclusion is that the predominant form of risk governance framework, with its focus on centralised decision-making and vertical knowledge transfer is insufficient to support risk-based, environmental policy making. We discuss how risk governance can better support environmental policy makers through systematic knowledge management practices
Church tradition and psychological type preferences among Anglicans in England
A sample of 290 individuals attending Evangelical Anglican churches and Anglo-Catholic churches in central England completed the Keirsey Temperament Sorter, a measure of psychological type preferences. Overall, there were clear preferences for sensing over intuition, for feeling over thinking, and for judging over perceiving, which is consistent with the findings of two earlier studies profiling the psychological type of Anglican churchgoers. However, there was also a significantly higher proportion of intuitives among Anglo-Catholics than among Evangelical Anglicans, which is consistent with the greater emphasis in Anglo-Catholic churches on mystery, awe, and the centrality of sacraments in worship which may resonate with the intuitive predisposition. The implications of these findings are discussed for the benefits of breadth and diversity within Anglicanism
Linear Taylor–Couette stability of a transversely isotropic fluid
Fibre-laden fluids are found in a variety of situations, while Couette devices are used for flow spectroscopy of long biological molecules, such as DNA and proteins in suspension. The presence of these fibres can significantly alter the rheology of the fluid, and hence must be incorporated in any modelling undertaken. A transversely isotropic fluid treats these suspensions as a continuum with an evolving preferred direction, through a modified stress tensor incorporating four viscosity-like parameters. We consider the axisymmetric linear stability of a transversely isotropic viscous fluid, contained between two rotating co-axial cylinders, and determine the critical wave and Taylor numbers for varying gap width and inner cylinder velocity (assuming the outer cylinder is fixed). Through the inclusion of transversely isotropic effects, the onset of instability is delayed, increasing the range of stable operating regimes. This effect is felt most strongly through incorporation of the anisotropic shear viscosity, although the anisotropic extensional viscosity also contributes. The changes to the rheology induced by the presence of the fibres therefore significantly alter the dynamics of the system, and hence should not be neglected
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