2,540 research outputs found
RECENT DEVELOPMENTS IN THE PROVISION OF PRO BONO LEGAL SERVICES BY ATTORNEYS IN SOUTH AFRICA
SUMMARYThis paper focuses on legal service delivery for the indigent by attorneys in private practice acting pro bono in civil rather than criminal matters. In this regard there have been and continue to be considerable gaps between the proper access to civil justice imperatives of constitutional South Africa and the status quo which has existed from the advent of a democratic South Africa until the present. Law as a vehicle for necessary positive change in the daily lives of South African residents is pertinently considered within the country’s woefully unequal socio-economic climate. This paper considers the role which pro bono work by private attorneys is playing and should play in promoting a more just and equitable society through proper access to justice. It explores the current position in South Africa as well as the position in selected foreign jurisdictions regarding pro bono services by attorneys in private practice in civil matters. Part of the discussion focuses on the question of whether pro bono work should be voluntary or mandatory. The merits of introducing a pro bono obligation are critically analysed by looking at the effect on both legal practitioners as well as those receiving the pro bono services. Having defined pro bono work, the practical need for pro bono work by lawyers in private practice is highlighted due to the dearth of legal aid in civil matters for indigent South Africans. Possible constitutional imperatives for the provision of free legal services in civil matters are highlighted. An important part of the paper is a reflection on some of the pro bono work being conducted by private firms of attorneys. The paper concludes with suggestions on means for establishing a more effective pro bono system in South Africa
Plagioclase Growth Rates Control Three-grain Junction Geometry in Dolerites and Gabbros
Measurements of dihedral angles at three-grain junctions in gabbros, involving two grains of plagioclase and one grain of another mineral, demonstrate that the median dihedral angle is generally the same for all minerals in any sample. The few exceptions to this can be attributed to reaction or to the cessation of growth of plagioclase during the last stages of solidification of highly evolved liquids that do not crystallize volumetrically important amounts of plagioclase. The dihedral angle is therefore primarily controlled by the growth behavior of plagioclase in the last remaining liquid. The final value of the dihedral angle is controlled by the extent to which plagioclase growth is accommodated on the (010) faces: low angles form when growth on the (010) faces is minor compared with that on the other growth faces, and high angles form when the (010) faces accommodate significant growth. The response of dihedral angles to changes in crystallization time is therefore explained by the changing response of plagioclase growth to cooling rate, with limited growth on (010) faces during rapid cooling (leading to a low dihedral angle) and more significant growth at slow cooling (leading to high dihedral angle). The correspondence between dihedral angle and plagioclase grain shape (as quantified by the average apparent aspect ratio observed in thin section) is clearly evident for non-fractionated bodies such as dolerite sills. Although the stratigraphic variation of the overall plagioclase grain shape in the floor cumulates of the Skaergaard Intrusion is broadly similar to that observed in sills, there is no correspondence to observed augite�plagioclase�plagioclase dihedral angles, which show a step-wise stratigraphic variation, corresponding to changes in the liquidus assemblage. This decoupling occurs because plagioclase growth in layered intrusions occurs in two stages, the first at, or close to, the magma�mush interface and the second within the mush. Chemical maps of samples on either side of the augite-in dihedral angle step demonstrate a step-wise change in the aspect ratio of the plagioclase grown during the second stage, with the aspect ratio of this stage corresponding to that predicted from the dihedral angles. Plagioclase shape in layered intrusions thus records two separate thermal regimes, with the overall shape controlled by the global cooling rate of the intrusion, and the second (minor) stage within the mushy layer reflecting local thermal buffering controlled by the liquidus assemblage of the bulk magma. Dihedral angles in layered intrusions record the second thermal regime
The effect of crystallization time on plagioclase grain shape in dolerites
The average aspect ratio of plagioclase, measured in thin section, varies systematically through dolerite sills, with a symmetrical “M” shaped profile observed in sills thinner than ~200m. Thicker sills show the same marginal reversal at the base but average aspect ratios appear to continue increasing towards the top, creating an “S” shaped profile. A distorted “M” shaped profile is visible in the stratigraphic variation of plagioclase average aspect ratios in the prehistoric Makaopuhi lava lake, with the lowest aspect ratio observed in the olivine-enriched horizon close to the base of the lake. Higher overall values of average aspect ratio are observed in thin sills compared to thicker sills, demonstrating that the plagioclase in more slowly crystallised bodies is more equant than that in more rapidly crystallised bodies. There is a strong correlation between the plagioclase average aspect ratio in the central parts of the sills and the crystallization time calculated using a simple one-dimensional thermal model assuming conductive cooling. The cause of the marginal reversals in average aspect ratio is not well understood but may result from early grain impingement in the developing crystal mushy layer.This is the final version. It was first published by Springer at http://link.springer.com/article/10.1007%2Fs00410-014-1076-
The campsite dykes: A window into the early post-solidification history of the Skaergaard Intrusion, East Greenland
publication-status: Publishedtypes: ArticleThis is an open access article.The Skaergaard Intrusion of East Greenland is cut by several generations of dykes, the earliest of which is thought to have intruded shortly after solidification of the Skaergaard. Two ~ 6 m wide doleritic dykes from the earliest generation are exposed in the campsite area near Homestead Bay of the Skaergaard Peninsula. One of the dykes (the Campsite Dyke) locally contains abundant xenoliths of troctolitic cumulate. The other (the Plagioclase-phyric Dyke) contains abundant large plagioclase phenocrysts. Cross-cutting relationships between the two dykes are not exposed. The median clinopyroxene–plagioclase–plagioclase dihedral angle, Θcpp, in the Campsite Dyke is 88–89.5°, whereas that of the Plagioclase-phyric Dyke is 79°. Using an empirical relationship between Θcpp and the duration of crystallisation derived from dolerite sills, the observed Θcpp suggests that the Campsite Dyke is the older of the two, intruding the Skaergaard when it had cooled to 920–970 °C. The Plagioclase-phyric Dyke intruded later, once the Skaergaard had cooled below 670 °C. The troctolitic xenoliths divide into two separate groups. Type A xenoliths have microstructures similar to those of the Skaergaard Layered Series although mineral compositions are generally more primitive than those of the exposed cumulates — this type of xenolith is likely to have been derived from either deeper levels in the Skaergaard Intrusion or from a closely-related underlying magma chamber. One Type A xenolith has mineral compositions and Θcpp consistent with an origin in LZb of the Layered Series — this xenolith contains partially inverted pigeonite, suggesting that inversion of low-Ca pyroxene in the lower part of the Layered Series took place after the intrusion had completely solidified. Type B xenoliths are characterized by plagioclase containing large and abundant melt inclusions. Comparison with the microstructures of glassy crystalline nodules from Iceland points to a multi-stage cooling history for Type B xenoliths, consistent with step-wise entrainment of partially crystallised material from a deep chamber. Type B xenoliths are very unlikely to have been derived from deeper levels in the Skaergaard chamber.We thank Madeleine Humphreys for her assistance in collecting samples from the Campsite area. We are grateful to Monica Price of the Oxford University Natural History Museum for access to samples from the Wager East Greenland collection, and to Christian Tegner and Kent Brooks for loan of the sample from the Campsite Dyke chill zone. John Maclennan loaned us material from Iceland and we both thank him and David Neave for interesting discussions about their microstructures. Insightful and helpful comments from Tony Morse and an anonymous reviewer greatly improved an earlier version of this contribution. QEMSCAN® is a registered trademark of FEI Company. FEI Company sponsored the QEMSCAN® analyses, which were completed by Dr Gavyn Rollinson, at Camborne School of Mines, University of Exeter, UK. This work was supported by the Natural Environment Research Council [grant numbers NE/F020325/1 and NE/J021520/1]
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Orientation of tabular mafic intrusions controls convective vigour and crystallization style
The microstructure in basaltic dykes is significantly different to that in sills and lava lakes of the same bulk composition. For a given width of intrusion (or depth of lava lake), vertical tabular bodies are coarser-grained than horizontal bodies, with an invariant plagioclase shape across the intrusion. When comparing samples from sills and dykes for which the average grain size is the same, the dyke samples contain fewer small grains and fewer large grains than the sill samples. In contrast, the variation of median clinopyroxene-plagioclase-plagioclase dihedral angles in dykes correlates precisely with that observed in sills and is a function of the rate of diffusive heat loss. These patterns can be accounted for if the early stages of crystallization in dykes primarily involve the growth of isolated grains suspended in a well-mixed convecting magma, with the final stage (during which dihedral angles form) occurring in a crystal-rich static magma during which heat loss is primarily diffusive. In contrast, crystallization in sills occurs predominantly in marginal solidification fronts, suggesting that any convective motions are insufficient to entrain crystals from the marginal mushy layers and to keep them suspended while they grow.
An exception to this general pattern is provided by members of the Mull Solitary Dykes, which propagated 100-1000 km SE from the Mull Palaeogene Igneous Centre, Scotland, through the shallow crust. These dykes, where sampled > 100 km from Mull, have a microstructure indistinguishable from that of a sill of comparable thickness. We suggest that sufficient nucleation and crystallization occurred in these dykes to increase the viscosity sufficiently to damp convection once unidirectional flow had ceased
Crystal settling and convection in the Shiant Isles Main Sill
The 168 m-thick Shiant Isles Main Sill is a composite body, dominated by an early, 24 m-thick, picrite sill formed by the intrusion of a highly olivine-phyric magma, and a later 135 m-thick intrusion of olivine-phyric magma that split the earlier picrite into a 22 m-thick lower part and a 2 m-thick upper part, forming the picrodolerite/crinanite unit (PCU). The high crystal load in the early picrite prevented effective settling of the olivine crystals, which retain their initial stratigraphic distribution. In contrast, the position of the most evolved rocks of the PCU at a level ~80% of its total height point to significant accumulation of crystals on the floor, as evident by the high olivine mode at the base of the PCU. Crystal accumulation on the PCU floor occurred in two stages. During the first, most of the crystal load settled to the floor to form a modally and size-sorted accumulation dominated by olivine, leaving only the very smallest olivine grains still in suspension. The second stage is recorded by the coarsening-upwards of individual olivine grains in the picrodolerite, and their amalgamation into clusters which become both larger and better sintered with increasing stratigraphic height. Large clusters of olivine are present at the roof, forming a foreshortened mirror image of the coarsening-upwards component of the floor accumulation. The coarsening-upwards sequence records the growth of olivine crystals while in suspension in a convecting magma, and their aggregation into clusters, followed by settling over a prolonged period (with limited trapping at the roof). As olivine was progressively lost from the convecting magma, crystal accumulation on the (contemporaneous) floor of the PCU was increasingly dominated by plagioclase, most likely forming clusters and aggregates with augite and olivine, both of which form large poikilitic grains in the crinanite. While the PCU is unusual in being underlain by an earlier, still hot, intrusion that would have enhanced any driving force for convection, we conclude from comparison with microstructures in other sills that convection is likely in tabular bodies >100 m thickness
A hydrogeomorphological approach to quantification of groundwater discharge to streams in South Africa
In South Africa, the flow requirements for maintaining the normal functioning of aquatic ecosystems is termed the “ecological
reserve”, and these should be determined when a licence application for water allocation is processed. Determination of the
ecological reserve entails investigation of the relationship between the major interactive components of the hydrologic cycle,
namely groundwater and surface water bodies including rivers, lakes and estuaries. Information on groundwater discharge towards
surface water bodies is critical for the water resource manager to make a decision regarding the amount of groundwater allocation
that can be licensed without causing a negative impact on aquatic ecosystems. Existing techniques of hydrograph-separation are
too subjective either due to the fact that assumptions of the techniques cannot be met in reality or that the parameters used in models
do not have physical meanings. This paper presents a geomorphologic framework under which the quantification of groundwater
from a hydrograph is discussed. A focus is placed on hydrogeomorphological typing that can be used to guide a process of separating
groundwater discharge time series from hydrographs where a monthly groundwater discharge time series is required for comparison
with instream flow requirements. For generating monthly groundwater discharge time series, a generic procedure is proposed,
which is applied in a case study.Web of Scienc
Microstructural evidence for crystallization regimes in mafic intrusions: a case study from the Little Minch Sill Complex, Scotland
The magma forming the 20 m thick crinanitic/picrodoleritic Dun Raisburgh sill, part of the Little Minch Sill Complex of NW Scotland, comprised a mafic carrier liquid with a crystal cargo of plagioclase and olivine (1 vol%). The olivine component of the cargo settled on the floor of the intrusion while the more buoyant plagioclase component remained suspended during solidification, resulting in a relatively high plagioclase content in the centre of the sill. The settled olivine grains form a lower fining-upwards sequence overlain by a poorly sorted accumulation formed of grains that grew within the convecting magma. The accumulation of olivine on the sill floor occurred over 5–10 weeks, synchronous with the upwards-propagation of a solidification front comprising a porous (~ 70 vol% interstitial liquid) plagioclase-rich crystal mush
Scavenger receptor structure and function in health and disease.
Scavenger receptors (SRs) are a 'superfamily' of membrane-bound receptors that were initially thought to bind and internalize modified low-density lipoprotein (LDL), though it is currently known to bind to a variety of ligands including endogenous proteins and pathogens. New family of SRs and their properties have been identified in recent years, and have now been classified into 10 eukaryote families, defined as Classes A-J. These receptors are classified according to their sequences, although in each class they are further classified based in the variations of the sequence. Their ability to bind a range of ligands is reflected on the biological functions such as clearance of modified lipoproteins and pathogens. SR members regulate pathophysiological states including atherosclerosis, pathogen infections, immune surveillance, and cancer. Here, we review our current understanding of SR structure and function implicated in health and disease
A mineralogical and microstructural study of 7 eucrites (A-881394, Y-791195, Y-981617, Y-790266, Y-791186, Y-792510, Y-793591).
第3回極域科学シンポジウム/第35回南極隕石シンポジウム 11月29日(木) 国立国語研究所 2階講
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