153 research outputs found
Die inhoud en die doel van die Nederduitsch Hervormde Kerk se bediening, met verwysing na die ampte
The substance and purpose of the ministry of the Nederduitsch Hervormde Kerk, with reference to ecclesiastical offices.
For close on a decade, the Nederduitsch Hervormde Kerk van Afrika has been debating the issue of appropriate structures and patterns for its ministry. In this article it is argued that the debate not only reflects dissatisfaction with structures and patterns, but also brings to light dissatisfaction with the substance and purpose of the ministry of the Word as such. The ministry of the church should be understood in the light of the essence of being a church, which resides in the fact that the church belongs to the Lord. It is possible to belong to the Lord only on the basis of faith in the Word of God. The church, therefore, has one ministry only: the ministry of the Word. Appropriate ecclesiastical offices, structures and patterns are those that minister the Word
High-speed photometry of the eclipsing polar UZ Fornacis
We present 33 new mid-eclipse times spanning approximately eight years of the
eclipsing polar UZ Fornacis. We have used our new observations to test the
two-planet model previously proposed to explain the variations in its eclipse
times measured over the past 35 years. We find that the proposed model
does indeed follow the general trend of the new eclipse times, however, there
are significant departures. In order to accommodate the new eclipse times, the
two-planet model requires that one or both of the planets require highly
eccentric orbits, that is, 0.4. Such multiple planet orbits are
considered to be unstable. Whilst our new observations are consistent with two
cyclic variations as previously predicted, significant residuals remain. We
conclude that either additional cyclic terms, possibly associated with more
planets, or other mechanisms, such as the Applegate mechanism are contributing
to the eclipse time variations. Further long-term monitoring is required.Comment: 11 pages, 5 figures, Accepted for publication in A&
IGR J19552+0044: A new asynchronous short period polar: "Filling the gap between intermediate and ordinary polars"
Based on XMM--Newton X-ray observations IGR J19552+0044 appears to be either
a pre-polar or an asynchronous polar. We conducted follow-up optical
observations to identify the sources and periods of variability precisely and
to classify this X-ray source correctly. Extensive multicolor photometric and
medium- to high-resolution spectroscopy observations were performed and period
search codes were applied to sort out the complex variability of the object. We
found firm evidence of discording spectroscopic (81.29+/-0.01m) and photometric
(83.599+/-0.002m) periods that we ascribe to the white dwarf (WD)\ spin period
and binary orbital period, respectively. This confirms that IGR J19552+0044 is
an asynchronous polar. Wavelength-dependent variability and its continuously
changing shape point at a cyclotron emission from a magnetic WD with a
relatively low magnetic field below 20 MG.
The difference between the WD spin period and the binary orbital period
proves that IGR J19552+0044 is a polar with the largest known degree of
asynchronism (0.97 or 3%).Comment: 9 pages, 10 figures, A&A accepte
Diversity and biogeographical patterns of legumes (Leguminosae) indigenous to southern Africa
The principal aim of this study was to establish biogeographical patterns in the legume flora of southern
Africa so as to facilitate the selection of species with agricultural potential. Plant collection data from the
National Herbarium, South Africa, were analysed to establish the diversity and areas covered by legumes
(Leguminosae/Fabaceae) indigenous to South Africa, Lesotho and Swaziland. A total of 27,322 records
from 1,619 quarter degree grid cells, representing 1,580 species, 122 genera and 24 tribes were included
in the analyses. Agglomerative hierarchical clustering was applied to the presence or absence of legume
species in quarter degree grid cells, the resultant natural biogeographical regions (choria) being referred
to as leguminochoria. The description of the 16 uniquely formed leguminochoria focuses on defining
the associated bioregions and biomes, as well as on the key climate and soil properties. Legume species
with a high occurrence in a leguminochorion are listed as key species. The dominant growth form of key
species, species richness and range within each leguminochorion is discussed. Floristic links between the
leguminochoria are established, by examining and comparing key species common to clusters, using a
vegetation classification program. Soil pH and mean annual minimum temperature were found to be the main drivers for distinguishing among legume assemblages. This is the first time that distribution data for
legumes has been used to identify biogeographical areas covered by leguminochoria on the subcontinent.
One potential application of the results of this study is to assist in the selection of legumes for pasture
breeding and soil conservation programs, especially in arid and semi-arid environments.This paper is dedicated to the memory of Robert Howard (Bobby) Westfall
(17 December 1944–21 January 2016), vegetation ecologist and friend
whose sudden death during the preparation of this manuscript deprived
us of an invaluable collaborator.Financial assistance from the University of Pretoria is acknowledged
with thanks.http://phytokeys.pensoft.nethttp://opendatacommons.org/licenses/odbl/1.0/am2016Plant Scienc
The structure of Chariklo's rings from stellar occultations
Two narrow and dense rings (called C1R and C2R) were discovered around the
Centaur object (10199) Chariklo during a stellar occultation observed on 2013
June 3. Following this discovery, we planned observations of several
occultations by Chariklo's system in order to better characterize the physical
properties of the ring and main body. Here, we use 12 successful occulations by
Chariklo observed between 2014 and 2016. They provide ring profiles (physical
width, opacity, edge structure) and constraints on the radii and pole position.
Our new observations are currently consistent with the circular ring solution
and pole position, to within the km formal uncertainty for the ring
radii derived by Braga-Ribas et al. The six resolved C1R profiles reveal
significant width variations from to 7.5 km. The width of the fainter
ring C2R is less constrained, and may vary between 0.1 and 1 km. The inner and
outer edges of C1R are consistent with infinitely sharp boundaries, with
typical upper limits of one kilometer for the transition zone between the ring
and empty space. No constraint on the sharpness of C2R's edges is available. A
1 upper limit of m is derived for the equivalent width of
narrow (physical width <4 km) rings up to distances of 12,000 km, counted in
the ring plane
Diversity and biogeographical patterns of legumes (Leguminosae) indigenous to southern Africa
This paper is dedicated to the memory of Robert Howard (Bobby) Westfall
(17 December 1944–21 January 2016), vegetation ecologist and friend
whose sudden death during the preparation of this manuscript deprived
us of an invaluable collaborator.The principal aim of this study was to establish biogeographical patterns in the legume flora of southern
Africa so as to facilitate the selection of species with agricultural potential. Plant collection data from the
National Herbarium, South Africa, were analysed to establish the diversity and areas covered by legumes
(Leguminosae/Fabaceae) indigenous to South Africa, Lesotho and Swaziland. A total of 27,322 records
from 1,619 quarter degree grid cells, representing 1,580 species, 122 genera and 24 tribes were included
in the analyses. Agglomerative hierarchical clustering was applied to the presence or absence of legume
species in quarter degree grid cells, the resultant natural biogeographical regions (choria) being referred
to as leguminochoria. The description of the 16 uniquely formed leguminochoria focuses on defining
the associated bioregions and biomes, as well as on the key climate and soil properties. Legume species
with a high occurrence in a leguminochorion are listed as key species. The dominant growth form of key
species, species richness and range within each leguminochorion is discussed. Floristic links between the
leguminochoria are established, by examining and comparing key species common to clusters, using a
vegetation classification program. Soil pH and mean annual minimum temperature were found to be the main drivers for distinguishing among legume assemblages. This is the first time that distribution data for
legumes has been used to identify biogeographical areas covered by leguminochoria on the subcontinent.
One potential application of the results of this study is to assist in the selection of legumes for pasture
breeding and soil conservation programs, especially in arid and semi-arid environments.Financial assistance from the University of Pretoria is acknowledged
with thanks.http://phytokeys.pensoft.nethttp://opendatacommons.org/licenses/odbl/1.0/am2016Plant Scienc
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