416 research outputs found
Jurassic formation and Eocene subduction of the Zermatt-Saas-Fee ophiolites: implications for the geodynamic evolution of the Central and Western Alps
MEDIUM-TERM ANALYSIS OF FISCAL POLICY IN IRELAND: A MACROECONOMETRIC STUDY OF THE PERIOD 1967-1980. ESRI General Research Series Paper No. 122, July 1985
The decade of the 1970s was characterised by fluctuations in the world
economy of a kind whicb had not been experienced in peacetime since the
1930s. Even with the wisest and most prudent fiscal and monetary policies
it would have been impossible to protect the Irish economy fully from the
world-wide recession. Our objective in this paper is to investigate what effect
fiscal policies had on tile evolution of the Irish economy over the period
1967 to 1980 and, with the benefit of hindsight, to attempt to formulate a
judgement as to the manner in which fiscal policy was planned and executed.
The "hindsight" from which we benefit has two major components: first
our access to data which are at once more detailed and accurate than those
available to successive Ministers of Finance at the time when they planned
their budget strategies and second our use of a formal model of how the
various sectors and agents in the economy interact with each other and evolve
over time. While the first component (more accurate data) is an unqualified
benefit, the second component (the model) is much more controversial since
there is no absolute consensus in the economics profession on broad areas
of macroeconomic theory and modelling practice. We are fully conscious of
this problem and hope that the reader will not interpret our formal and
detailed quantitative analysis as implying either ignorance or arrogance on our
part in respect of the current very active international research into the
foundations of macroeconomic theory and practice. It remains, of course,
for the reader to decide whether our judgement, in relation to the gross
simplifications needed in order to construct an operation’,d model of the
economy, has been good or bad
Dating the Triassic continental rift in the southern Andes : The Potrerillos Formation, Cuyo Basin, Argentina
The Triassic successions of western Argentina commonly show thin pyroclastic levels intercalated within thick fluvial and lacustrine terrigenous deposits. The Potrerillos Formation is the thickest Triassic unit in the Cuyo Basin. It is composed of alternating cycles of gravelly- sandy- and muddy-dominated intervals, in which several laterally-continuous tuff horizons occur. U-Pb SHRIMP ages were determined on zircon grains from three tuff levels located between the lowermost and the middle sections of the Potrerillos Formation. The ages for the time of deposition of the tuffs are 239.2 ± 4.5 Ma, 239.7 ± 2.2 Ma and 230.3 ± 2.3 Ma (Middle Triassic). Chemical data indicate that these acid to intermediate volcaniclastic rocks are derived from coeval basic magmas displaying tholeiitic to slightly alkaline signatures. They are associated with the rift stage that followed the extensive post-orogenic volcanism of the Choiyoi Group, that in turn has been ascribed to slab break-off in neighbouring areas. Two of the studied samples also record a subpopulation of inherited zircon grains with crystallisation ages of 260-270 Ma. The latter are considered to be an indirect measurement for the age of the Choiyoi Group in the Cuyo basin. The rift-related Triassic event represents the culmination of the Gondwanian magmatic cycle, and is interpreted as the result of subduction cessation and anomalous heating of the upper mantle previous to the western Gondwana break-up.Centro de Investigaciones Geológica
Dating the Triassic continental rift in the southern Andes : The Potrerillos Formation, Cuyo Basin, Argentina
The Triassic successions of western Argentina commonly show thin pyroclastic levels intercalated within thick fluvial and lacustrine terrigenous deposits. The Potrerillos Formation is the thickest Triassic unit in the Cuyo Basin. It is composed of alternating cycles of gravelly- sandy- and muddy-dominated intervals, in which several laterally-continuous tuff horizons occur. U-Pb SHRIMP ages were determined on zircon grains from three tuff levels located between the lowermost and the middle sections of the Potrerillos Formation. The ages for the time of deposition of the tuffs are 239.2 ± 4.5 Ma, 239.7 ± 2.2 Ma and 230.3 ± 2.3 Ma (Middle Triassic). Chemical data indicate that these acid to intermediate volcaniclastic rocks are derived from coeval basic magmas displaying tholeiitic to slightly alkaline signatures. They are associated with the rift stage that followed the extensive post-orogenic volcanism of the Choiyoi Group, that in turn has been ascribed to slab break-off in neighbouring areas. Two of the studied samples also record a subpopulation of inherited zircon grains with crystallisation ages of 260-270 Ma. The latter are considered to be an indirect measurement for the age of the Choiyoi Group in the Cuyo basin. The rift-related Triassic event represents the culmination of the Gondwanian magmatic cycle, and is interpreted as the result of subduction cessation and anomalous heating of the upper mantle previous to the western Gondwana break-up.Centro de Investigaciones Geológica
Neutral genomic microevolution of a recently emerged pathogen, salmonella enterica serovar agona
Salmonella enterica serovar Agona has caused multiple food-borne outbreaks of gastroenteritis since it was first isolated in
1952. We analyzed the genomes of 73 isolates from global sources, comparing five distinct outbreaks with sporadic
infections as well as food contamination and the environment. Agona consists of three lineages with minimal mutational
diversity: only 846 single nucleotide polymorphisms (SNPs) have accumulated in the non-repetitive, core genome since
Agona evolved in 1932 and subsequently underwent a major population expansion in the 1960s. Homologous
recombination with other serovars of S. enterica imported 42 recombinational tracts (360 kb) in 5/143 nodes within the
genealogy, which resulted in 3,164 additional SNPs. In contrast to this paucity of genetic diversity, Agona is highly diverse
according to pulsed-field gel electrophoresis (PFGE), which is used to assign isolates to outbreaks. PFGE diversity reflects a
highly dynamic accessory genome associated with the gain or loss (indels) of 51 bacteriophages, 10 plasmids, and 6
integrative conjugational elements (ICE/IMEs), but did not correlate uniquely with outbreaks. Unlike the core genome, indels
occurred repeatedly in independent nodes (homoplasies), resulting in inaccurate PFGE genealogies. The accessory genome
contained only few cargo genes relevant to infection, other than antibiotic resistance. Thus, most of the genetic diversity
within this recently emerged pathogen reflects changes in the accessory genome, or is due to recombination, but these
changes seemed to reflect neutral processes rather than Darwinian selection. Each outbreak was caused by an independent
clade, without universal, outbreak-associated genomic features, and none of the variable genes in the pan-genome seemed
to be associated with an ability to cause outbreaks
New strawberry breeding lines – enhanced phytochemical composition and bioaccessibility
Screening of phytochemicals has been of interest in strawberry genotypes as there is emerging evidence from epidemiological and clinical studies that consumption of phytochemical-rich strawberry cultivars may provide health benefits. The aim of the present study was (1) to quantify selected phytochemicals in new strawberry breeding lines (BL) and (2) to assess the in vitro bioaccessibility of phytochemicals as an initial measure to predict their bioavailability
U-Pb SHRIMP zircon dating of andesite from the Dolomite area (NE Italy): geochronological evidence for the early onset of Permian Volcanism in the eastern part of the southern Alps
The Athesian Volcanic District (AVD), a thick sequence of andesitic to rhyolitic lava and ignimbrite, overlies both the Variscan basement of the Dolomites and, where present, the continental basal conglomerate of Upper Carboniferous(?) to Early Permian age. This volcanic activity is known to mark the margin of the intra-Pangea megashear system between Gondwana and Laurasia, the onset age of which is determined in this study. SHRIMP U-Pb dating on zircon from Ponte Gardena/Waidbruck (Isarco/Eisack valley) basaltic andesite yields an age of 290.7 ± 3 Ma, providing the oldest record of andesite volcanic activity yet documented in the AVD. Two younger dates (279.9 ± 3.3 and 278.6 ± 3.1 Ma) obtained for the andesitic necks of M. dei Ginepri (Eores/Aferer valley) and Col Quaterna (western Comelico), respectively, probably represent a second pulse of andesite magmatic activity. Near Chiusa/Klausen, the volcanoclastic deposits at the bottom of the Funes/Villnoss valley volcano-sedimentary complex only contain detrital zircons, dated at 469 ± 6 Ma; these probably derive from erosion of Paleozoic porphyroids. Other zircons from the same sediments and inherited cores of magmatic andesite crystals give Paleoproterozoic (1953.6 ± 22.1, 1834.6 ± 69.3, 1773.6 ± 25.1 Ma), Early Neoproterozoic (1015 ± 14 Ma) and Late Neoproterozoic (728.4 ± 9.6, 687.6 ± 7.6 Ma) ages. These ancient detrital and inherited zircon ages fit the model that envisages the Dolomite region as being tectonically coherent with Africa, at least until the Lower Permian
Proterozoic crustal evolution of central East Antarctica: Age and isotopic evidence from glacial igneous clasts, and links with Australia and Laurentia
Rock clasts entrained in glacial deposits sourced from the continental interior of Antarctica provide an innovative means to determine the age and composition of ice-covered crust. Zircon U-Pb ages from a suite of granitoid clasts collected in glacial catchments draining central East Antarctica through the Transantarctic Mountains show that crust in this region was formed by a series of magmatic events at ∼2.01, 1.88–1.85, ∼1.79, ∼1.57, 1.50–1.41, and 1.20–1.06 Ga. The dominant granitoid populations are ca. 1.85, 1.45 and 1.20–1.06 Ga. None of these igneous ages are known from limited outcrop in the region. In addition to defining a previously unrecognized geologic history, zircon O and Hf isotopic compositions from this suite have: (1) mantle-like δ18O signatures (4.0–4.5‰) and near-chondritic Hf-isotope compositions (εHf ∼ +1.5) for granitoids of ∼2.0 Ga age; (2) mostly crustal δ18O (6.0–8.5‰) and variable Hf-isotope compositions (εHf = −6 to +5) in rocks with ages of ∼1.88–1.85, ∼1.79 and ∼1.57 Ga, in which the ∼1.88–1.79 Ga granitoids require involvement of older crust; (3) mostly juvenile isotopic signatures with low, mantle-like δ18O (∼4–5‰) and radiogenic Hf-isotope signatures (εHf = +6 to +10) in rocks of 1.50–1.41 Ga age, with some showing crustal sources or evidence of alteration; and (4) mixed crustal and mantle δ18O signatures (6.0–7.5‰) and radiogenic Hf isotopes (εHf = +3 to +4) in rocks of ∼1.2 Ga age. Together, these age and isotopic data indicate the presence in cratonic East Antarctica of a large, composite igneous province that formed through a punctuated sequence of relatively juvenile Proterozoic magmatic events. Further, they provide direct support for geological correlation of crust in East Antarctica with both the Gawler Craton of present-day Australia and Proterozoic provinces in western Laurentia. Prominent clast ages of ∼2.0, 1.85, 1.57 and 1.45 Ga, together with sediment source linkages, provide evidence for the temporal and spatial association of these cratonic elements in the Columbia supercontinent. Abundant ∼1.2–1.1 Ga igneous and metamorphic clasts may sample crust underlying the Gamburtsev Subglacial Mountains, indicating the presence of a Mesoproterozoic orogenic belt in the interior of East Antarctica that formed during final assembly of Rodinia.Field and analytical portions of this project were supported by the
National Science Foundation (award 0944645)
Variscan sourcing of Westphalian (Pennsylvanian) sandstones in the Canobie Coalfield, UK
The zircon age spectrum in a sample from the Canonbie Bridge Sandstone Formation
(Asturian) of southern Scotland contains two main peaks. One is Early Carboniferous in age (348–
318 Ma), and corresponds to the age of igneous activity during the Variscan Orogeny. The other is of
late Neoproterozoic to early Cambrian age (693–523 Ma), corresponding to the Cadomian. Together,
these two groups comprise 70 % of the zircon population. The presence of these two peaks shows
unequivocally that a significant proportion of the sediment was derived from the Variscides of western
or central Europe. The zircon population also contains a range of older Proterozoic zircons and a small
Devonian component. These could have been derived from the Variscides, but it is possible that some
were locally derived through recycling of northerly derived sandstones of Devonian–Carboniferous
age. The zircon age data confirm previous suggestions of Variscide sourcing to the Canonbie area,
made on the basis of petrographical, heavy mineral and palaeocurrent evidence, and extend the known
northward distribution of Variscan-derived Westphalian sediment in the UK
- …