1,769 research outputs found
The Common Frame of Reference in Europe
No full textDiscusses the origins of the Draft Common Frame of Reference and assesses the need for further work in particular areas, taking as an example the subject of restitutionary damages for non-performance of a contract. Also assesses the possible relevance of the DCFR in work on African legal unity
Symposium: Role of organisms and organic matter in ore deposition/Le rôle des organismes et de la matière organique dans la formation des gisements métallifères
No full text The following seven papers were presented on May 16, 1984, at the Geological Association of Canada and Mineralogical Association of Canada joint annual meeting. The special session, organized by R. W. Macqueen and J. A. Coope, contained 10 papers and was sponsored by the Mineral Deposits Division of the Geological Association of Canada.Our objective in organizing the special session was to examine organically based processes and relationships that may be of major importance to the origin of ore deposits. As noted by Fyfe (1984), the concept of the geochemical cycle focuses attention on pathways of chemical elements and isotopes of the Earth's system during geologic history. It is clear from the chemistry of carbon-rich materials that a wide range of elements is concentrated directly or indirectly by biological processes operating as part of the geochemical cycle. Two of the papers of the special session examine some of these concentration processes, although definitive links to actual ore deposits cannot be made yet. Beveridge and Fyfe document the remarkable ability of the anionic cell walls of certain bacteria to concentrate metals and to provide sites for nucleation and growth of minerals. In a related paper, Mann and Fyfe show that several species of simple freshwater green algae readily concentrate large amounts of uranium under both experimental and natural conditions (Elliot Lake and Thames River, Ontario).Two papers deal with aspects of sulphate reduction. Birnbaum and Wireman describe controlled experiments that suggest that sulphate-reducing bacteria may be involved in the selective replacement of sulphate-evaporite minerals by silica and in the precipitation of silica in association with sulphide mineral phases in banded iron formations. Their work focuses directly on the effect that bacterial sulphate reduction has on silica solubility. Trudinger et al. examine the question of mechanisms of sulphate reduction at temperatures less than 200 °C and the bearing this has on origin of sulphide for low-temperature sulphide ore deposits. Although there is empirical evidence favouring abiological sulphate reduction at temperatures in the vicinity of 100 °C, Trudinger et al. have not been able to demonstrate abiological reduction of sulphate under controlled laboratory conditions and at temperatures under about 200 °C. Perhaps catalysts, as yet undiscovered, are involved in this process in nature.Impressive progress has been made in understanding the diagenetic evolution of organic matter in response to heat and pressure in geological environments: excellent reviews are found in Barnes et al. (1984) and Bustin et al. (1985). Simoneit's paper examines and reviews the genesis of petroleum in a most unusual setting, that of the active ocean ridge spreading centre of Guaymas Basin, Gulf of California. There, in the vicinity of black smokers and associated metallic sulphide deposits, petroleum originates instantaneously geologically as a result of hydrothermal activity. The question of genetic involvement of organic matter in the origin of the metallic sulphides (e.g., reduction of sulphate to H2S) cannot be answered yet for this setting with the available data.The final two special session papers included here are concerned with organic matter associated with mineralization in Canadian Shield Precambrian settings. Willingham et al. demonstrate that Elliot Lake – Blind River Early Proterozoic uranium deposits with minor amounts of associated gold also contain kerogen-like organic matter. Some of this organic matter has anomalously rich amounts of gold and uranium and appears to have originated as mats of cyanobacteria, possibly with the ability to concentrate these metals. For a number of settings in the Archean-aged Abitibi greenstone belt of Ontario and Quebec, Springer demonstrates that carbon, at least partly of organic origin, is closely associated with some gold deposits. Her interpretation is that carbon activated by shear-zone-associated hydrothermal fluids has provided sites for fixing some of the gold.Three of the papers given at the special session are not included here. H. T. Shacklette reviewed metal uptake by young conifer trees, demonstrating that nursery-grown seedlings of several species readily concentrated a variety of metals, including lead, zinc, tin, and gold, over a 7 year period. This work is of interest to those involved in geochemical prospecting and is now published elsewhere (King et al. 1984). R. W. Macqueen presented quantitative data on the genesis of sulphide by abiological bitumen–sulphate reactions at the Pine Point lead–zinc property, Northwest Territories, Canada (Macqueen and Powell 1983; Powell and Macqueen 1984). Although Trudinger et al. have not been able to demonstrate abiological reduction of sulphate at temperatures approximating those of Pine Point [Formula: see text], the data presented by Macqueen (Powell and Macqueen 1984) are consistent with the amounts, alteration, and composition of bitumens at Pine Point, as well as with the presence of native sulphur and the sulphur isotope compositions of the various Pine Point sulphur species. This work is continuing, and a more extensive account is in preparation. J. R. Watterson examined relationships between freezing climates and the local chemical behaviour of gold in the weathering cycle, concluding that ice-induced accumulation of organic acids, bacteria, and other organic matter at mineral surfaces may increase rates of chemical attack, leading to dissolution of normally insoluble metals such as gold (Watterson 1986).Interest in organic aspects of the geochemical cycle, including ore deposition, is growing dramatically (e.g., Fyfe 1984). Although the following papers address a limited range of topics within the field, they do indicate some of the diversity and variety of active processes and associations between metallic elements and organic components. Perhaps, in the not too distant future, we will be able to identify or even discover whole classes of ore deposits that owe their origin directly to organic influences operating within the geochemical cycle. </jats:p
The lordship of Galloway c. 1000 to c. 1250
No full textThe recorded history of the lordship under the House of Fergus
lasted from only e. 1130 to 1231, but its origins lie in the fusion of
the various peoples settled there by c. 1000. A blend of Celtic and
Germanic groups created a hybrid culture that had more in common with
Man and the Isles than mainland Scotland. Galwegian attitudes to and
relationship with Scotland before c. 1130 are unclear, but ties with
York and Man had greater value than Scottish claims to overlordship.
The emergence of a powerful line of rulers kept the ambitions of the
Crown in check, but any divisions in their ranks were exploited by the
Scots. Close family links with the Plantagenet kings provided a
counterbalance to Scottish interference, but brought English
overlordship instead. This had the side-effect of securing the
separation of the see of Whithorn from the Scottish Church.
Marriage and kinship ties brought the lords political power in
Scotland, England and Man, and control of estates outwith the
lordship. This in turn led to the closer integration of Galloway into
Scotland as its rulers gained high office in the kingdom. Thus the
lords developed a dual character as Anglo-Scottish baron and Celtic
chieftain. Introduction of Normanised colonists and the development
of 'feudal' military tenures fostered this transition and eroded
regional particularism. Integration was accelerated by elimination of
the male line and partition between heiresses married into
Anglo-Norman families. Division broke the power of Galloway, weakened
the influence of its new rulers over the Galwegians and gave the Crown
the control for which it had long striven
Mary Macqueen & Insula
No full textThis thesis was scanned from the print manuscript for digital preservation and is copyright the author.
Researchers can access this thesis by asking their local university, institution or public library to
make a request on their behalf. Monash staff and postgraduate students can use the link in the References field
On the Bayesian analysis of species sampling mixture models for density estimation
No full textThe mixture of normals model has been extensively applied to density estimation problems.
This paper proposes an alternative parameterisation that naturally leads to new forms
of prior distribution. The parameters can be interpreted as the location, scale and smoothness
of the density. Priors on these parameters are often easier to specify. Alternatively, improper
and default choices lead to automatic Bayesian density estimation. The ideas are extended to
multivariate density estimation
An update on MyoD evolution in teleosts and a proposed consensus nomenclature to accommodate the tetraploidization of different vertebrate genomes
No full textDJM was supported by a Natural Environment Research Council studentship (NERC/S/A/2004/12435).Background: MyoD is a muscle specific transcription factor that is essential for vertebrate myogenesis. In several teleost species, including representatives of the Salmonidae and Acanthopterygii, but not zebrafish, two or more MyoD paralogues are conserved that are thought to have arisen from distinct, possibly lineage-specific duplication events. Additionally, two MyoD paralogues have been characterised in the allotetraploid frog, Xenopus laevis. This has lead to a confusing nomenclature since MyoD paralogues have been named outside of an appropriate phylogenetic framework. Methods and Principal Findings: Here we initially show that directly depicting the evolutionary relationships of teleost MyoD orthologues and paralogues is hindered by the asymmetric evolutionary rate of Acanthopterygian MyoD2 relative to other MyoD proteins. Thus our aim was to confidently position the event from which teleost paralogues arose in different lineages by a comparative investigation of genes neighbouring myod across the vertebrates. To this end, we show that genes on the single myod-containing chromosome of mammals and birds are retained in both zebrafish and Acanthopterygian teleosts in a striking pattern of double conserved synteny. Further, phylogenetic reconstruction of these neighbouring genes using Bayesian and maximum likelihood methods supported a common origin for teleost paralogues following the split of the Actinopterygii and Sarcopterygii. Conclusion: Our results strongly suggest that myod was duplicated during the basal teleost whole genome duplication event, but was subsequently lost in the Ostariophysi ( zebrafish) and Protacanthopterygii lineages. We propose a sensible consensus nomenclature for vertebrate myod genes that accommodates polyploidization events in teleost and tetrapod lineages and is justified from a phylogenetic perspective.Peer reviewe
Evolution of ancient functions in the vertebrate insulin-like growth factor system uncovered by study of duplicated salmonid fish genomes
No full textThis work was supported by the Marine Alliance for Science and Technology for Scotland pooling initiative, funded by the Scottish Funding Council (grant number HR09011) and contributing institutions.Whole genome duplication (WGD) was experienced twice by the vertebrate ancestor (2 rounds; 2R), again by the teleost fish ancestor (3R) and most recently in certain teleost lineages (4R). Consequently, vertebrate gene families are often expanded in 3R and 4R genomes. Arguably, many types of ‘functional divergence’ present across 2R gene families will exceed that between 3R/4R paralogues of genes comprising 2R families. Accordingly, 4R offers a form of replication of 2R. Examining if this concept has implications for molecular evolutionary research, we studied insulin-like growth factor (IGF) binding proteins (IGFBPs), whose six 2R family members carry IGF hormones and regulate interactions between IGFs and IGF1-receptors (IGF1Rs). Using phylogenomic approaches, we resolved the complete IGFBP repertoire of 4R-derived salmonid fishes (nineteen genes; thirteen more than human) and established evolutionary relationships/nomenclature with respect to WGDs. Traits central to IGFBP action were determined for all genes, including atomic interactions in IGFBP-IGF1/IGF2 complexes regulating IGF-IGF1R binding. Using statistical methods, we demonstrate that attributes of these protein interfaces are overwhelming a product of 2R IGFBP family membership, explain 49-68% of variation in IGFBP mRNA concentration in several different tissues and strongly predict the strength and direction of IGFBP transcriptional regulation under differing nutritional-states. The results support a model where vertebrate IGFBP family members evolved divergent structural attributes to provide distinct competition for IGFs with IGF1Rs, pre-disposing different functions in the regulation of IGF-signaling. Evolution of gene expression acted to ensure the appropriate physiological production of IGFBPs according to their structural specializations, leading to optimal IGF-signaling according to nutritional-status and the endocrine/local mode of action. This study demonstrates that relatively recent gene family expansion can facilitate inference of functional evolution within ancient genetic systems.Peer reviewe
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